国外数据库各学科高被引论文TOP5

2015-01-30

中国学术期刊文摘 2015年4期

关键词：出版物邮箱来源

高影响力文章

国外数据库各学科高被引论文TOP5

数据来源：Web of Science文献出版时间：2013.1—2014.11检索时间：2014.12.1

MATERIALS SCIENCE COATINGS FILMS 材料科学，涂料和薄膜

被引频次: 51

来源出版物: Journal of the Electrochemical Society, 2013, 160(2): A259–A267联系邮箱: Trahan, MJ; kmabraham@comcast.net

被引频次: 36

The Identification of Stable Solvents for Nonaqueous Rechargeable Li-Air Batteries

Bryantsev, VS; Uddin, J; Giordani, V; et al.

Abstract: Solvent plays a major role in determining the nature of discharge products and the extent of rechargeability of the nonaqueous lithium-air (oxygen) battery. Here we investigate chemical stability for a number of aprotic solvents against superoxide, including N,N-dialkyl amides, aliphatic and aromatic nitriles, oxygenated phosphorus (V) compounds, substituted 2-oxazolidinones, and fluorinated ethers. The free energy barriers for nucleophilic attack by superoxide and the C-H acidity constants in dimethyl sulfoxide are reported, which provide a theoretical framework for computational screening of stable solvents for Li-air batteries. Theoretical results are complemented by cyclic voltammetry to study the electrochemical reversibility of the O2/O2-couple containing tetrabutylammonium salt and GCMS measurements to monitor solvent stability in the presence of KO2and a Li salt. Excellent agreement among all quantum chemical, electrochemical, and chemical methods has been obtained in evaluating solvent stability against superoxide. The combined theoretical and experimental methodology provides a comprehensive testing ground to identify electrolyte solvents stable in the air cathode. Based upon this knowledge we report on the use of an amide-based electrolyte for rechargeable oxygen electrodes in Li-O2secondary cells.

Keywords: lithium-oxygen battery; base-catalyzed autoxidation; Li-O2batteries; electrochemical reduction; superoxide ion; carbonate electrolytes; liquid electrolytes; volume polarization; organic-solvents; aprotic-solvents

来源出版物: Journal of the Electrochemical Society, 2013, 160(1): A160–A171联系邮箱: Bryantsev, VS; slava@liox.com

被引频次: 30

Understanding Long-Term Cycling Performance of Li1.2Ni0.15Mn0.55Co0.1O2-Graphite Lithium-Ion Cells

Li, Y; Bettge, M; Polzin, B; et al.

Abstract: Lithium-ion cells containing lithium and manganese rich layered-oxides (LMR-NMC) have gained significant attention in recent years because of their ability to deliver high energy densities. In this article we report on a comprehensive performance and degradation study of cells, containing Li1.2Ni1.5Mn0.55Co0.1O2based positive electrodes and graphite based negative electrodes, on extended cycling. In addition to electrochemical measurements on full cells, characterization data on harvested electrodes by techniques that include scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Raman spectroscopy, and secondary ion mass spectrometry (SIMS) are discussed. Our data show that cell capacity fade mainly results from lithium trapping in the solid electrolyte interphase (SEI) of the negative electrode. In addition, cell impedance rise and voltage fade mainly arise at the positive electrode and result from degradation processes in its oxide and carbon constituents. Processes that include the accumulation of transition metal elements at the negative electrode, and increasing misalignment of electrode capacity windows on extended cycling, also have a deleterious effect on cellperformance. Identifying sources of performance degradation has enabled strategies to extend cell life, which include improved cell fabrication protocols, positive electrode coatings, and bifunctional electrolyte additives.

Keywords: x-ray-absorption; cathode materials; high-power; electrode materials; electrochemical intercalation; raman-spectroscopy; localstructure; energy-storage; high-capacity; oxygen loss

来源出版物: Journal of the Electrochemical Society, 2013, 160(5): A3006–A3019联系邮箱: Li, Y; abraham@anl.gov

被引频次: 29

Plasma etching: Yesterday, today, and tomorrow

Donnelly, VM; Kornblit, A

Abstract: The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir-Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

Keywords: high-density plasmas; ray photoelectron-spectroscopy; optical-emission-spectroscopy; electron-cyclotron-resonance; chemical-vapor-deposition; coupled chlorine plasmas; molecular-dynamics simulations; induced thermal-desorption; doped polycrystalline silicon; laser-induced fluorescence

来源出版物: Journal of Vacuum Science & Technology A, 2013, 31(5): 050825联系邮箱: Donnelly, VM; vmdonnelly@uh.edu

被引频次: 28

A Critical Review of the Li Insertion Mechanisms in LiFePO4 Electrodes

Malik, R; Abdellahi, A; Ceder, G

Abstract: With the ever-growing public and now commercial sentiment supporting the widespread adoption of low and zero-emission vehicles, it is unsurprising that Li-ion batteries which currently assume the bulk of the cost of electrified vehicles (a significant proportion coming from cost of battery materials) have become prolific not only in the primary research literature but have also entered the general public consciousuess. Since the initial work in 1997, over 2000 research publications have been authored on lithium iron phosphate (Li-FePO4), one of only a handful of commercially viable Li-ion battery cathode materials currently used in electrified vehicles. Despite the sheer quantity of research devoted to the subject and the well-demonstrated excellent battery performance of LiFePO4, what is surprising are the number of apparent discrepancies and ensuing contention in the literature regarding its (de)lithiation kinetics. This Review forgoes re-summarizing the well-accepted materials properties of LiFePO4and instead seeks to address headlong the specific areas of dispute in the field, specifically by considering how the thermodynamics and kinetics of Li intercalation are modified from the bulk to single-particle to multi-particle scales, shedding light on what makes LiFePO4such a unique material and ideally shaping future discourse of LiFePO4research.

Keywords: lithium-ion batteries; x-ray-diffraction; domino-cascade model; open-circuit voltage; phase-transition; cathode material; particle-size; room-temperature; electrochemical shock; nanoscale olivines

来源出版物: Journal of the Electrochemical Society, 2013, 160(5): A3179–A3197联系邮箱: Malik, R; gceder@mit.edu

MATERIALS SCIENCE COMPOSITES 复合材料学

被引频次: 43

A critical review of recent research on functionally graded plates

Jha, DK; Kant, T; Singh, RK

Abstract: In view of the significant increase in research activity and publications in functionally graded materials (FGMs) and structures in the last few years, the present article is an attempt to identify and highlight the topics that are most relevant to FGMs and structures and review representative journal publications that are related to those topics. A critical review of the reported studies in the area of thermo-elastic and vibration analyses of functionally graded (FG) plates with an emphasis on the recent works published since 1998. Because of the extensive growth in the body of knowledge in FGMs in the last two decades, it is prudent to reduce the review to a manageable level by concentrating on the FG plate problems only. The review carried out here, is concerned with deformation, stress, vibration and stability problems of FG plates. This review is intended to give the readers a feel for the variety of studies and applications related to graded composites. An effort has been made here, to include all the important contributions in the current area of interest. The critical areas regardingfuture research needs for the successful implementation of FGM in design are outlined in the conclusions.

Keywords: shear deformation-theory; higher-order shear; finite-element-method; transient thermal-stresses; electro-elastic plates; annular FGM plates; temperature-dependent properties; nonlinear bending response; large deflection analysis; thick rectangular-plates

来源出版物: Composite Structures, 2013, 96: 833–849联系邮箱: Jha, DK; z7404702@iitb.ac.in

被引频次: 38

Static, free vibration and buckling analysis of isotropic and sandwich functionally graded plates using a quasi-3D higher-order shear deformation theory and a meshless technique

Neves, AMA; Ferreira, AJM; Carrera, E; et al.

Abstract: In this paper the authors derive a higher-order shear deformation theory for modeling functionally graded plates accounting for extensibility in the thickness direction.

The explicit governing equations and boundary conditions are obtained using the principle of virtual displacements under Carrera's Unified Formulation. The static and eigenproblems are solved by collocation with radial basis functions.

The efficiency of the present approach is assessed with numerical results including deflection, stresses, free vibration, and buckling of functionally graded isotropic plates and functionally graded sandwich plates.

Keywords: radial basis functions; laminated composite plates; petrov-galerkin method; 3-dimensional elasticity solution; partial-differentialequations; computational fluid-dynamics; data approximation scheme; thick rectangular-plates; finite-element-analysis; closed-form solutions

来源出版物: Composites Part B–Engineering, 2013, 44(1): 657–674联系邮箱: Ferreira, AJM; ferreira@fe.up.pt

被引频次: 36

General higher-order shear deformation theories for the free vibration analysis of completely doubly-curved laminated shells and panels

Viola, E; Tornabene, F; Fantuzzi, N

Abstract: The main aim of this paper is to provide a general framework for the formulation and the dynamic analysis computations of moderately thick laminated doubly-curved shells and panels. A 2D higher-order shear deformation theory is also proposed and the differential geometry is used to define the arbitrary shape of the middle surface of shells and panels with different curvatures.

A generalized nine-parameter displacement field suitable to represent in a unified form most of the kinematical hypothesis presented in literature has been introduced.

Formal comparison among various theories have been performed in order to show the differences between the well-known First-order Shear Deformation Theory (FSDT) and several Higher-order Shear Deformation Theories (HSDTs).

The 2D free vibration shell problems have been solved numerically using the Generalized Differential Quadrature (GDQ) technique. The GDQ rule has been also used to perform the numerical evaluation of the derivatives of the quantities involved by the differential geometry to completely describe the reference surfaces of doubly-curved shell structures.

Numerical investigations concerning four types of shell structures have been carried out. GDQ results are compared with those presented in literature and the ones obtained using commercial programs such as Abaqus. Very good agreement is observed.

Keywords: differential quadrature method; composite plates; cylindrical-shells; static analysis; thickness locking; stress continuity; revolution; GDQ; model; beam

来源出版物: Composite Structures, 2013, 95: 639–666联系邮箱: Viola, E; erasmo.viola@unibo.it

被引频次: 34

Green composites: A review of adequate materials for automotive applications

Koronis, G; Silva, A; Fontul, M

Abstract: This study provides a bibliographic review in the broad field of green composites seeking-out for materials with a potential to be applied in the near future on automotive body panels. Hereupon, materials deriving from renewable resources will be preferred as opposed to the exhaustible fossil products. With the technical information of bio-polymers and natural reinforcements a database was created with the mechanical performance of several possible components for the prospect green composite. Following the review, an assessment is performed where aspects of suitability for the candidate elements in terms of mechanical properties are analyzed. In that section, renewable materials for matrix and reinforcement are screened accordingly in order to identify which hold both adequate strength and stiffness performance along with affordable cost so as to be a promising proposal for a green composite.

Keywords: natural fibers; mechanical-properties; renewable resources; plastic composites; PLA composites; flax fiber; hemp fiber; jute; polypropylene; biopolymers

来源出版物: Composites Part B–Engineering, 2013, 44(1): 120–127联系邮箱: Koronis, G; gkoronis@gmail.com

被引频次: 32

Axial Compressive Behavior of Square and Rectangular High-Strength Concrete-Filled FRP Tubes

Ozbakkaloglu, T

Abstract: This paper presents results of an experimental study on the behavior of square and rectangular high-strength concrete (HSC)-filled fiber-reinforced polymer (FRP) tubes (HSCFFT) under concentric compression. The effects of the tube thickness, sectional aspect ratio, and corner radius on the axial compressive behavior of concrete-filled FRP tubes (CFFT) were investigated experimentally through the tests of 24 CFFTs that were manufactured using unidirectional carbon fiber sheets and high-strength concrete with 78 MPa average compressive strength. As the first experimental investigation on the axial compressive behavior of square and rectangular HSCFFTs, the results of the study reported in this paper allow a number of significant conclusions to be drawn. First and foremost, test results indicate that sufficiently confined square and rectangular HSCFFTs can exhibit highly ductile behavior. The results also indicate that confinement effectiveness of FRP tubes increases with an increase in corner radius and decreases with an increase in sectional aspect ratio. It is also observed and discussed that HSCFFTs having tubes of low confinement effectiveness may experience a significant strength loss at the point of transition on their stress-strain curves. Furthermore, it is found that the behavior of HSCFFTs at this region differ from that of normal-strength CFFTs and that it is more sensitive to the effectiveness of a confining tube. Examination of the test results have also lead to a number of important observations on the influence of the key confinement parameters on the development and distribution of the hoop strains on the tubes of CFFTs, which are presented and discussed in the paper.

Keywords: reinforced polymer tubes; confined concrete; seismic performance; composite jackets; columns; cylinders; model; manufacture来源出版物: Journal of Composites For Construction, 2013, 17(1): 151–161

联系邮箱: Ozbakkaloglu, T; tozbakka@civeng.adelaide.edu.au

MATERIALS SCIENCE MULTIDISCIPLINARY 材料科学，综合

被引频次: 296

Solar cell efficiency tables (version 41)

Green, MA; Emery, K; Hishikawa, Y; et al.

Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since June 2012 are reviewed.

Keywords: multicrystalline; concentrator; stability

来源出版物: Progress in Photovoltaics, 2013, 21(1): 1–11联系邮箱: Green, MA; m.green@unsw.edu.au

被引频次: 228

Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Butler, SZ; Hollen, SM; Cao, LY; et al.

Abstract: Graphene's success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in field-effect transistors, spin- and valley-tronics, thermoelectrics, and topological insulators, among many other applications.

Keywords: chemical-vapor-deposition; der-waals epitaxy; hexagonal boron-nitride; single-layer MoS2; field-effect transistors; transition-metal dichalcogenides; scanning-tunneling-microscopy; topological insulator nanoribbons; lithium intercalation properties; langmuir-blodgett deposition

来源出版物: ACS Nano, 2013, 7(4): 2898–2926联系邮箱: Goldberger, JE; goldberger@chemistry.ohio-state.edu

被引频次: 225

Raman spectroscopy as a versatile tool for studying the properties of graphene

Ferrari, AC; Basko, DM

Abstract: Raman spectroscopy is an integral part of graphene research. It is used to determine the number and orientation of layers, the quality and types of edge, and the effects of perturbations, such as electric and magnetic fields, strain, doping, disorder and functional groups. This, in turn, provides insight into all sp(2)-bonded carbon allotropes, because graphene is their fundamental building block. Herewe review the state of the art, future directions and open questions in Raman spectroscopy of graphene. We describe essential physical processes whose importance has only recently been recognized, such as the various types of resonance at play, and the role of quantum interference. We update all basic concepts and notations, and propose a terminology that is able to describe any result in literature. We finally highlight the potential of Raman spectroscopy for layered materials other than graphene.

Keywords: carbon nanotubes; light-scattering; layer graphene; graphite; crystals; mode; electron; spectrum; films; band

来源出版物: Nature Nanotechnology, 2013, 8(4): 235–246联系邮箱: Ferrari, AC; acf26@eng.cam.ac.uk

被引频次: 200

Chemical Management for Colorful, Efficient, and Stable Inorganic-Organic Hybrid Nanostructured Solar Cells

Noh, JH; Im, SH; Heo, JH; et al.

Abstract: Chemically tuned inorganic-organic hybrid materials, based on CH3NH3(=MA)Pb(I1-xBrx)(3) perovskites, have been studied using UV-vis absorption and X-ray diffraction patterns and applied to nanostructured solar cells. The band gap engineering brought about by the chemical management of MAPb(I1-xBrx)(3) perovskites can be controllably tuned to cover almost the entire visible spectrum, enabling the realization of colorful solar cells. We demonstrate highly efficient solar cells exhibiting 12.3% in a power conversion efficiency of under standard AM 1.5, for the most efficient device, as a result of tunable composition for the light harvester in conjunction with a mesoporous TiO2film and a hole conducting polymer. We believe that the works highlighted in this paper represent one step toward the realization of low-cost, high-efficiency, and long-term stability with colorful solar cells.

Keywords: organometal halide perovskites; nanowires; crystals

来源出版物: Nano Letters, 2013, 13(4): 1764–1769联系邮箱: Seok, SI; seoksi@krict.re.kr

被引频次: 196

Thin film solar cell with 8.4% power conversion efficiency using an earth-abundant Cu2ZnSnS4absorber

Shin, B; Gunawan, O; Zhu, Y; et al.

Abstract: Using vacuum process, we fabricated Cu2ZnSnS4solar cells with 8.4% efficiency, a number independently certified by an external, accredited laboratory. This is the highest efficiency reported for pure sulfide Cu2ZnSnS4prepared by any method. Consistent with literature, the optimal composition is Cu-poor and Zn-rich despite the precipitation of secondary phases (e.g., ZnS). Despite a very thin absorber thickness (similar to 600 nm), a reasonably good short-circuit current was obtained. Time-resolved photoluminescence measurements suggest a minority carrier-diffusion length on the order of several hundreds of nanometers and relatively good collection of photo-carriers across the entire absorber thickness.

来源出版物: Progress in Photovoltaics, 2013, 21(1): 72–76联系邮箱: Guha, S; guha@us.ibm.com

MATERIALS SCIENCE PAPER WOOD 材料科学，造纸材

被引频次: 40

Idealized powder diffraction patterns for cellulose polymorphs

French, AD

Abstract: Cellulose samples are routinely analyzed by X-ray diffraction to determine their crystal type (polymorph) and crystallinity. However, the connection is seldom made between those efforts and the crystal structures of cellulose that have been proposed with synchrotron X-radiation and neutron diffraction over the past decade or so. In part, this desirable connection is thwarted by the use of different conventions for description of the unit cells of the crystal structures. In the present work, powder diffraction patterns from cellulose I alpha, I beta, II, IIII, and IIIII were calculated based on the published atomic coordinates and unit cell dimensions contained in modified "crystal information files" (.cif) that are supplied in the Supplementary Information. The calculations used peak widths at half maximum height of both 0.1 and 1.5A degrees 2 theta, providing both highly resolved indications of the contributions of each contributing reflection to the observable diffraction peaks as well as intensity profiles that more closely resemble those from practical cellulose samples. Miller indices are shown for each contributing peak that conform to the convention with c as the fiber axis, a right-handed relationship among the axes and the length of a < b. Adoption of this convention, already used for crystal structure determinations, is also urged for routine studies of polymorph and crystallinity. The calculated patterns are shown with and without preferred orientation along the fiber axis. Diffraction intensities, output by the Mercury program from the Cambridge Crystallographic Data Centre, have several uses including comparisons with experimental data. Calculated intensities from different polymorphs can be added in varying proportions using a spreadsheet program to simulate patterns such as those from partially mercerized cellulose or various composites.

Keywords: neutron fiber diffraction; synchrotron x-ray; hydrogen-bonding system; crystal-structure; packing analysis; polysaccharides; model

来源出版物: Cellulose, 2014, 21(2): 885–896联系邮箱: French, AD; cellulose.editor@gmail.com

被引频次: 40

Cellulose polymorphy, crystallite size, and the Segal Crystallinity Index

French, AD; Cintron, MS

Abstract: The X-ray diffraction-based Segal Crystallinity Index (CI) was calculated for simulated different sizes of crystallites for cellulose I beta and II. The Mercury software was used, and different crystallite sizes were based on different input peak widths at half of the maximum peak intensity (pwhm). The two cellulose polymorphs, I beta and II, gave different CIs despite having the same pwhm values and perfect periodicity. The higher CIs for cellulose II were attributed to a greater distance between the major peaks that are closest to the recommended 2-theta value for assessing the amorphous content. That results in less peak overlap at the recommended 2-theta value. Patterns calculated with simulated preferred orientation had somewhat higher CIs for cellulose I beta, whereas there was very little effect on the CIs for cellulose II.

Keywords: FT-raman-spectroscopy; i crystallinity; x-ray

来源出版物: Cellulose, 2013, 20(1): 583–588联系邮箱: French, AD; al.french@ars.usda.gov

被引频次: 23

A critical discussion of the physics of wood-water interactions

Engelund, ET; Thygesen, LG; Svensson, S; et al.

Abstract: This paper reviews recent findings on wood-water interaction and puts them into context of established knowledge in the field. Several new findings challenge prevalent theories and are critically discussed in an attempt to advance current knowledge and highlight gaps. The focus of this review is put on water in the broadest concept of wood products, that is, the living tree is not considered. Moreover, the review covers the basic wood-water relation, states and transitions. Secondary effects such as the ability of water to alter physical properties of wood are only discussed in cases where there is an influence on state and/or transition.

Keywords: fiber saturation point; differential scanning calorimetry; moisture sorption hysteresis; furfurylated norway spruce; proton magnetic-resonance; independent-domain theory; cell-wall; cellulose microfibril; dimensional changes; tropical hardwoods

来源出版物: Wood Science and Technology, 2013, 47(1): 141–161联系邮箱: Engelund, ET; ete@teknologisk.dk

被引频次: 15

Zero-order drug release cellulose acetate nanofibers prepared using coaxial electrospinning

Yu, DG; Li, XY; Wang, X; et al.

Abstract: Novel drug-loaded cellulose acetate (CA) nanofibres were prepared by a modified coaxial electrospinning process, after which their zero-order drug release profiles were determined. Using 2 % (w/v) unspinnable CA solution as a sheath fluid, coaxial electrospinning can be conducted smoothly to generate ketoprofen (KET)-loaded CA nanofibres coated with a thin layer of blank CA. Scanning electron microscopy images demonstrated that nanofibres obtained from the modified coaxial process have a smaller average diameter, a narrower size distribution, more uniform structures, and smoother surface morphologies than those generated from single-fluid electrospinning. Transmission electron microscopy observations demonstrated that the nanofibres have a thin coating layer of blank CA on their surface with a thickness of ca. 15 nm. X-ray diffraction and differential scanning calorimetry verified that KET molecules in all of the nanofibres presented an amorphous state. Fourier transform infrared spectra demonstrated that CA has good compatibility with KET, which is brought about by hydrogen bonding. In vitro dissolution tests showed that the nanofibres coated with blank CA have no initial burst release effects and can provide a zero-order drug release profile over 96 h via a diffusion mechanism. The modified coaxial electrospinning method can provide new approaches in developing cellulose-based nano products with definite structural characteristics and improved functional performance.

Keywords: solvent system; fibers; adsorption; membrane

来源出版物: Cellulose, 2013, 20(1): 379–389联系邮箱: Yu, DG; ydg017@gmail.com

被引频次: 13

Novel concepts of dissolving pulp production

Sixta, H; Iakovlev, M; Testova, L; et al.

Abstract: Herein, we report about existing and novel dissolving pulp processes providing the basis for an advanced biorefinery. The SO2-ethanol-water (SEW) process has the potential to replace the acid sulphite process for the production of rayon-grade pulps owing to a higher flexibility in the selection of the raw material source, substantially lower cooking times, and the near absence of sugar degradation products. Special attention is paid to developments that target toward the selective and quantitative fractionation of paper-grade pulps into hemicelluloses and cellulose of highest purity. This target has been accomplished by the IONCELL process where the entire hemicellulosefraction is selectively dissolved in an ionic liquid in which the H-bond basicity and acidity are adequately adjusted by the addition of a co-solvent. At the same time, pure hemicellulose can be recovered by further addition of the co-solvent, which then acts as a non-solvent. The residual pure cellulose fraction may then enter a Lyocell process for the production of regenerated cellulose products.

Keywords: hot-water extraction; paper-grade pulps; birch wood; nitren extraction; mass balances; delignification; cellulose; sulfur; autohydrolysis; parameters

来源出版物: Cellulose, 2013, 20(4): 1547–1561联系邮箱: Sixta, H; Herbert.Sixta@tkk.fi

MATERIALS SCIENCE TEXTILES 材料科学，纺织

被引频次: 45

Perylene diimides based materials for organic solar cells

Kozma, E; Catellani, M

Abstract: Perylene-3,4,9,10-tetracarboxylic acid diimides (PDIs) and their derivatives represent one of the most promising class of electron accepting materials, due to their outstanding chemical and physical properties, including high electron mobility and high molar absorption coefficients. Their rigid, fused aromatic core favours pi-pi intermolecular interactions imparting n-type semiconducting properties useful for optoelectronic applications. The PDIs have attracted interest as photovoltaic functional materials for their strong electron-accepting character and significant charge transport properties. This feature article describes the application of PDI based molecules and polymers in organic photovoltaic solar cells.

Keywords: field-effect transistors; heterojunction photovoltaic devices; open-circuit voltage; photocurrent generation; optical-properties; functional-groups; electron-transfer; block-copolymers; broad absorption; bisimide units

来源出版物: Dyes and Pigments, 2013, 98(1): 160–179联系邮箱: Kozma, E; erika.kozma@ismac.cnr.it

被引频次: 40

Idealized powder diffraction patterns for cellulose polymorphs

French, AD

Keywords: neutron fiber diffraction; synchrotron x-ray; hydrogen-bonding system; crystal-structure; packing analysis; polysaccharides; model

来源出版物: Cellulose, 2014, 21(2): 885–896联系邮箱: French, AD; cellulose.editor@gmail.com

被引频次: 40

Cellulose polymorphy, crystallite size, and the Segal Crystallinity Index

French, AD; Cintron, MS

Keywords: FT-raman-spectroscopy; i crystallinity; x-ray

来源出版物: Cellulose, 2013, 20(1): 583–588联系邮箱: French, AD; al.french@ars.usda.gov

被引频次: 29

Fluorescent dye containing phenol-pyridyl for selective detection of aluminum ions

Lee, J; Kim, H; Kim, S; et al.

Abstract: A phenol-pyridylimine probe was utilized as an optical sensor to quantify the presence of aluminum ions using a turn-on fluorescence enhancement approach. The high sensitivity was the result of FRET amplification of the receptor subunit fluorescence emission. The complex stability constant (K-s) for the stoichiometric 1:1 complex of the sensor with aluminum ions was obtained by fluorimetric titration. Remarkably, fluorescence output was not significantly affected by other trivalent cations, particularly Ga3+and In3+.

Keywords: Al3+ion; chemosensor; disease; toxicity; sensor; probe; model

来源出版物: Dyes and Pigments, 2013, 96(2): 590–594联系邮箱: Kim, C; chealkim@snut.ac.kr

被引频次: 24

A highly selective "turn-on" fluorescent chemosensor based on hydroxy pyrene-hydrazone derivative for Zn2+

Choi, JY; Kim, D; Yoon, J

Abstract: A new hydroxypyrene-based sensor 1 was designed and synthesized as a Zn2+selective colorimetric and fluorescent chemosensor. This chemosensor showed a new UV-vis absorption peak (lambda(max)=498 nm) with Zn2+, which can be attributed to an internal charge transfer (ICT) mechanism. In addition, Zn2+induced a highly selective "turn-on" fluorescence enhancement at long wavelength (lambda(max)=588 nm) in a buffered system. A significant fluorescence enhancement was observed upon the addition of Zn2+. The combination of two phenol groups on the pyrene and phenyl moieties as well as a conjugated hydrazone group can generate a binding pocket for Zn2+. These results also demonstrate that 1-hydroxypyrene-2-carboaldehyde can be a unique platform to introduce various ligands for the colorimetric and fluorescent recognition of metal ions.

Keywords: zinc ions; metal-ions; aqueous-solution; charge-transfer; recent progress; sensor; design; fluorophore; biosensors; switches

来源出版物: Dyes and Pigments, 2013, 96(1): 176–179联系邮箱: Yoon, J; jyoon@ewha.ac.kr

MATHEMATICAL COMPUTATIONAL BIOLOGY 数学计算生物学

被引频次: 313

GROMACS 4.5: a high-throughput and highly parallel open source molecular simulation toolkit

Pronk, S; Pall, S; Schulz, R; et al.

Abstract: Motivation: Molecular simulation has historically been a low-throughput technique, but faster computers and increasing amounts of genomic and structural data are changing this by enabling large-scale automated simulation of, for instance, many conformers or mutants of biomolecules with or without a range of ligands. At the same time, advances in performance and scaling now make it possible to model complex biomolecular interaction and function in a manner directly testable by experiment. These applications share a need for fast and efficient software that can be deployed on massive scale in clusters, web servers, distributed computing or cloud resources.

Results: Here, we present a range of new simulation algorithms and features developed during the past 4 years, leading up to the GROMACS 4.5 software package. The software now automatically handles wide classes of biomolecules, such as proteins, nucleic acids and lipids, and comes with all commonly used force fields for these molecules built-in. GROMACS supports several implicit solvent models, as well as new free-energy algorithms, and the software now uses multithreading for efficient parallelization even on low-end systems, including windows-based workstations. Together with hand-tuned assembly kernels and state-of-the-art parallelization, this provides extremely high performance and cost efficiency for high-throughput as well as massively parallel simulations.

Keywords: force-field; free-energy; biomolecular simulation; dynamics; model; refinement; transition; efficient; constant; proteins

来源出版物: Bioinformatics, 2013, 29(7): 845–854联系邮箱: Lindahl, E; erik.lindahl@scilifelab.se

被引频次: 234

Integrative Genomics Viewer (IGV): high-performance genomics data visualization and exploration

Thorvaldsdottir, H; Robinson, JT; Mesirov, JP

Abstract: Data visualization is an essential component of genomic data analysis. However, the size and diversity of the data sets produced by today's sequencing and array-based profiling methods present major challenges to visualization tools. The Integrative Genomics Viewer (IGV) is a high-performance viewer that efficiently handles large heterogeneous data sets, while providing a smooth and intuitive user experience at all levels of genome resolution. A key characteristic of IGV is its focus on the integrative nature of genomic studies, with sup-port for both array-based and next-generation sequencing data, and the integration of clinical and phenotypic data. Although IGV is often used to view genomic data from public sources, its primary emphasis is to support researchers who wish to visualize and explore their own data sets or those from colleagues. To that end, IGV supports flexible loading of local and remote data sets, and is optimized to provide high-performance data visualization and exploration on standard desktop systems. IGV is freely available for download from http://www.broadinstitute.org/igv, under a GNU LGPL open-source license.

来源出版物: Briefings in Bioinformatics, 2013, 14(2): 178–192联系邮箱: Robinson, JT; jrobinso@broadinstitute.org

被引频次: 96

STAR: ultrafast universal RNA-seq aligner

Dobin, A; Davis, CA; Schlesinger, F; et al.

Abstract: Motivation: Accurate alignment of high-throughput RNA-seq data is a challenging and yet unsolved problem because of the non-contiguous transcript structure, relatively short read lengths and constantly increasing throughput of the sequencing technologies. Currently available RNA-seq aligners suffer from high mapping error rates, low mapping speed, read length limitation and mapping biases.

Results: To align our large (> 80 billon reads) ENCODE Transcriptome RNA-seq dataset, we developed the Spliced Transcripts Alignment to a Reference (STAR) software based on a previously undescribed RNA-seq alignment algorithm that uses sequential maximum mappable seed search in uncompressed suffix arrays followed by seed clustering and stitching procedure. STAR outperforms other aligners by a factor of > 50 in mapping speed, aligning to the human genome 550 million 2 x 76 bp paired-end reads per hour on a modest 12-core server, while at the same time improving alignment sensitivity and precision. In addition to unbiased de novo detection of canonical junctions, STAR can discover non-canonical splices and chimeric (fusion) transcripts, and is also capable of mapping full-length RNA sequences. Using Roche 454 sequencing of reverse transcription polymerase chain reaction amplicons, we experimentally validated 1960 novel intergenic splice junctions with an 80-90% success rate, corroborating the high precision of the STAR mapping strategy.

Keywords: splice junctions; alignment; reads; algorithms; sequence; genomes; encode

来源出版物: Bioinformatics, 2013, 29(1): 15–21联系邮箱: Dobin, A; dobin@cshl.edu

被引频次: 79

MicroRNAs in Human Cancer

Farazi, TA; Hoell, JI; Morozov, P; et al.

Abstract: Mature microRNAs (miRNAs) are single-stranded RNA molecules of 20-23-nucleotide (nt) length that control gene expression in many cellular processes. These molecules typically reduce the translation and stability of mRNAs, including those of genes that mediate processes in tumorigenesis, such as inflammation, cell cycle regulation, stress response, differentiation, apoptosis, and invasion. miRNA targeting is initiated through specific base-pairing interactions between the 5' end ("seed" region) of the miRNA and sites within coding and untranslated regions (UTRs) of mRNAs; target sites in the 3' UTR lead to more effective mRNA destabilization. Since miRNAs frequently target hundreds of mRNAs, miRNA regulatory pathways are complex. To provide a critical overview of miRNA dysregulation in cancer, we first discuss the methods currently available for studying the role of miRNAs in cancer and then review miRNA genomic organization, biogenesis, and mechanism of target recognition, examining how these processes are altered in tumorigenesis. Given the critical role miRNAs play in tumorigenesis processes and their disease specific expression, they hold potential as therapeutic targets and novel biomarkers.

Keywords: rna-binding protein; target messenger-rnas; chronic lymphocytic-leukemia; to-mesenchymal transition; progressive hearing-loss; 3' untranslated region; renal-cell carcinoma; human breast-cancer; down-regulation; caenorhabditis-elegans

来源出版物: Microrna Cancer Regulation: Advanced Concepts, Bioinformatics and Systems Biology Tools, 2013, 774: 1–20

联系邮箱: Tuschl, T; ttuschl@mail.rockefeller.edu

被引频次: 66

An overview of the Amber biomolecular simulation package

Salomon-Ferrer, R; Case, DA; Walker, RC

Abstract: Molecular dynamics (MD) allows the study of biological and chemical systems at the atomistic level on timescales from femtoseconds to milliseconds. It complements experiment while also offering a way to follow processes difficult to discern with experimental techniques. Numerous software packages exist for conducting MD simulations of which one of the widest used is termed Amber. Here, we outline the most recent developments, since version 9 was released in April 2006, of the Amber and AmberTools MD software packages, referred to here as simply the Amber package. The latest release represents six years of continued development, since version 9, by multiple research groups and the culmination of over 33 years of work beginning with the first version in 1979. The latest release of the Amber package, version 12 released in April 2012, includes a substantial number of important developments in both the scientific and computer science arenas. We present here a condensed vision of what Amber currently supports and where things are likely to head over the comingyears. Figure 1 shows the performance in ns/day of the Amber package version 12 on a single-core AMD FX-8120 8-Core 3.6GHz CPU, the Cray XT5 system, and a single GPU GTX680.

Keywords: thermal rate constants; quantum instanton approximation; poisson-boltzmann solvers; path-integral evaluation; transition-state theory; isotropic periodic sum; particle mesh ewald; molecular-dynamics; force-field; statistical-mechanics

来源出版物: Wiley Interdisciplinary Reviews–computational Molecular Science, 2013, 3(2): 198–210

联系邮箱: Walker, RC; ross@rosswalker.co.uk

MATHEMATICS APPLIED应用数学

被引频次: 38

The operational matrix of fractional integration for shifted Chebyshev polynomials

Bhrawy, AH; Alofi, AS

Abstract: A new shifted Chebyshev operational matrix (SCOM) of fractional integration of arbitrary order is introduced and applied together with spectral tau method for solving linear fractional differential equations (FDEs). The fractional integration is described in the Riemann-Liouville sense. The numerical approach is based on the shifted Chebyshev tau method. The main characteristic behind the approach using this technique is that only a small number of shifted Chebyshev polynomials is needed to obtain a satisfactory result. Illustrative examples reveal that the present method is very effective and convenient for linear multi-term FDEs.

Keywords: differential-equations; series approach; identification; order; system

来源出版物: Applied Mathematics Letters, 2013, 26(1): 25–31联系邮箱: Bhrawy, AH; alibhrawy@yahoo.co.uk

被引频次: 37

Global exponential stability for BAM neural networks with time-varying delays in the leakage terms

Liu, BW

Abstract: In this paper, we first investigate the existence of a unique equilibrium to general bidirectional associative memory neural networks with time-varying delays in the leakage terms by the fixed point theorem. Then, by constructing a Lyapunov functional, we establish some sufficient conditions on the global exponential stability of the equilibrium for such neural networks, which substantially extend and improve the main results of Gopalsamy [K. Gopalsamy, Leakage delays in BAM, J. Math. Anal. Appl. 325 (2007) 1117-1132].

来源出版物: Nonlinear Analysis–real World Applications, 2013, 14(1): 559–566联系邮箱: Liu, BW; liubw007@yahoo.com.cn

被引频次: 36

Chaos-enhanced accelerated particle swarm optimization

Gandomi, AH; Yun, GJ; Yang, XS; et al.

Abstract: There are more than two dozen variants of particle swarm optimization (PSO) algorithms in the literature. Recently, a new variant, called accelerated PSO (APSO), shows some extra advantages in convergence for global search. In the present study, we will introduce chaos into the APSO in order to further enhance its global search ability. Firstly, detailed studies are carried out on benchmark problems with twelve different chaotic maps to find out the most efficient one. Then the chaotic APSO (CAPSO) will be compared with some other chaotic PSO algorithms presented in the literature. The performance of the CAPSO algorithm is also validated using three engineering problems. The results show that the CAPSO with an appropriate chaotic map can clearly outperform standard APSO, with very good performance in comparison with other algorithms and in application to a complex problem.

Keywords: structural optimization; global optimization; design optimization; genetic algorithms; integer; map

来源出版物: Communications in Nonlinear Science and Numerical Simulation, 2013, 18(2): 327–340

联系邮箱: Yun, GJ; a.h.gandomi@gmail.com

被引频次: 35

Consensus of multi-agent systems with nonlinear dynamics and sampled-data information: a delayed-input approach

Wen, GH; Duan, ZS; Yu, WW; et al.

Abstract: This paper is concerned with the problem of consensus in directed networks of multiple agents with intrinsic nonlinear dynamics and sampled-data information. A new protocol is induced from a class of continuous-time linear consensus protocols by implementing data-sampling technique and a zero-order hold circuit. On the basis of a delayed-input approach, the sampled-data multi-agent system is converted to an equivalent nonlinear system with a time-varying delay. Theoretical analysis on this time-delayed system shows that consensus with asymptotic time-varying velocities in a strongly connected network can be achieved over some suitable sampled-data intervals. A multi-step procedure is further presented to estimate the upper bound of the maximal allowable sampling intervals. The results are then ex-tended to a network topology with a directed spanning tree. For the case of the topology without a directed spanning tree, it is shown that the new protocol can still guarantee the system to achieve consensus by appropriately informing a fraction of agents. Finally, some numerical simulations are presented to demonstrate the effectiveness of the theoretical results and the dependence of the upper bound of maximal allowable sampling interval on the coupling strength.

Keywords: double-integrator dynamics; switching topology; cooperative control; time-delay; networks; agents; synchronization; coordination; algorithms; stability

来源出版物: International Journal of Robust and Nonlinear Control, 2013, 23(6): 602–619联系邮箱: Duan, ZS; duanzs@pku.edu.cn

被引频次: 32

The Time-Fractional Coupled-Korteweg-de-Vries Equations

Atangana, A; Secer, A

Abstract: We put into practice a relatively new analytical technique, the homotopy decomposition method, for solving the nonlinear fractional coupled-Korteweg-de-Vries equations. Numerical solutions are given, and some properties exhibit reasonable dependence on the fractional-order derivatives' values. The fractional derivatives are described in the Caputo sense. The reliability of HDM and the reduction in computations give HDM a wider applicability. In addition, the calculations involved in HDM are very simple and straightforward. It is demonstrated that HDM is a powerful and efficient tool for FPDEs. It was also demonstrated that HDM is more efficient than the adomian decomposition method (ADM), variational iteration method (VIM), homotopy analysis method (HAM), and homotopy perturbation method (HPM).

来源出版物: Abstract and Applied Analysis, 2013: 947986联系邮箱: Secer, A; asecer@yildiz.edu.tr

MATHEMATICS INTERDISCIPLINARY APPLICATIONS 数学，综合应用

被引频次: 73

Hierarchical multi-innovation stochastic gradient algorithm for Hammerstein nonlinear system modeling

Ding, F

Abstract: This paper decomposes a Hammerstein nonlinear system into two subsystems, one containing the parameters of the linear dynamical block and the other containing the parameters of the nonlinear static block, and presents a hierarchical multi-innovation stochastic gradient identification algorithm for Hammerstein systems based on the hierarchical identification principle. The proposed algorithm is simple in principle and easy to implement on-line. A simulation example is provided to test the effectiveness of the proposed algorithm.

Keywords: squares identification methods; errors-in-variables; dual-rate systems; parameter-estimation; armax systems; accuracy

来源出版物: Applied Mathematical Modelling, 2013, 37(4): 1694–1704联系邮箱: Ding, F; fding@jiangnan.edu.cn

被引频次: 62

TD-DFT benchmarks: A review

Laurent, AD; Jacquemin, D

Abstract: Time-Dependent Density Functional Theory (TD-DFT) has become the most widely-used theoretical approach to simulate the optical properties of both organic and inorganic molecules. In this contribution, we review TD-DFT benchmarks that have been performed during the last decade. The aim is often to pinpoint the most accurate or adequate exchange-correlation functional(s). We present both the different strategies used to assess the functionals and the main results obtained in terms of accuracy. In particular, we discuss both vertical and adiabatic benchmarks and comparisons with both experimental and theoretical reference transition energies. More specific benchmarks (oscillator strengths, excited-state geometries, dipole moments, vibronic shapes, etc.) are summarized as well.

Keywords: density-functional theory; generalized-gradient-approximation; excited-state properties; charge-transfer excitations; exchange-correlation functionals; circular-dichroism spectra; sensitized solar-cells; hartree-fock exchange; electronic-transition energies; polarizable continuum model

来源出版物: International Journal of Quantum Chemistry, 2013, 113(17): 2019–2039

联系邮箱: Laurent, AD; Denis.Jacquemin@univ–nantes.fr

被引频次: 55

Two-stage least squares based iterative estimation algorithm for CARARMA system modeling

Ding, F

Abstract: For stochastic systems described by the controlled autoregressive autoregressive moving average (CARARMA) models, a new-type two-stage least squares based iterative algorithm is proposed for identifying the system model parameters and the noise model parameters. The basic idea is based on the interactive estimation theory and to estimate the parameter vectors of the system model and thenoise model, respectively. The simulation results indicate that the proposed algorithm is effective.

Keywords: parameter-estimation algorithm; rate stochastic-systems; moving average systems; state-space models; dual-rate systems; identification methods; performance analysis; forgetting factor; auxiliary model; miso systems

来源出版物: Applied Mathematical Modelling, 2013, 37(7): 4798–4808联系邮箱: Ding, F; fding@jiangnan.edu.cn

被引频次: 43

The effects of MHD and temperature dependent viscosity on the flow of non-Newtonian nanofluid in a pipe: Analytical solutions

Ellahi, R

Abstract: This article examines the magnetohydrodynamic (MHD) flow of non-Newtonian nanofluid in a pipe. The temperature of the pipe is assumed to be higher than the temperature of the fluid. In particular two temperature dependent viscosity models, have been considered. The nonlinear partial differential equations along with the boundary conditions are first cast into a dimensionless form and then the equations are solved by homotopy analysis method (HAM). Explicit analytical expressions for the velocity field, the temperature distribution and nano concentration have been derived analytically. The effects of various physical parameters on velocity, temperature and nano concentration are discussed by using graphical approach.

Keywords: homotopy analysis method; 3rd grade fluid; differential-equations

来源出版物: Applied Mathematical Modelling, 2013, 37(3): 1451–1467联系邮箱: Ellahi, R; rellahi@engr.ucr.edu

被引频次: 40

Combined state and least squares parameter estimation algorithms for dynamic systems

Ding, F

Abstract: The control theory and automation technology cast the glory of our era. Highly integrated computer chip and automation products are changing our lives. Mathematical models and parameter estimation are basic for automatic control. This paper discusses the parameter estimation algorithm of establishing the mathematical models for dynamic systems and presents an estimated states based recursive least squares algorithm, and the states of the system are computed through the Kalman filter using the estimated parameters. A numerical example is provided to confirm the effectiveness of the proposed algorithm.

Keywords: moving average systems; box-jenkins systems; identification methods; performance analysis; iterative estimation; model

来源出版物: Applied Mathematical Modelling, 2014, 38(1): 403–412联系邮箱: Ding, F; fding@jiangnan.edu.cn

MATHEMATICS 数学

被引频次: 32

The Time-Fractional Coupled-Korteweg-de-Vries Equations

Atangana, A; Secer, A

来源出版物: Abstract and Applied Analysis, 2013: 947986联系邮箱: Secer, A; asecer@yildiz.edu.tr

被引频次: 29

Variational Methods for Non-Local Operators of Elliptic Type

Servadei, R; Valdinoci, E

Abstract: In this paper we study the existence of non-trivial solutions for equations driven by a non-local integrodifferential operator L-K with homogeneous Dirichlet boundary conditions. More precisely, we consider the problem

{L(K)u + lambda u + f(x, u)=0 in Omega u=0 in R-n backslash Omega,

where lambda is a real parameter and the nonlinear term f satisfies superlinear and subcritical growth conditions at zero and at infinity. This equation has a variational nature, and so its solutions can be found as critical points of the energy functional J(lambda) associated to the problem. Here we get such critical points using both the Mountain Pass Theorem and the Linking Theorem, respectively when lambda < lambda(1) and lambda≥lambda(1), where lambda(1) denotes the first eigenvalue of the operator -L-K.

As a particular case, we derive an existence theorem for the following equation driven by the fractional Laplacian

{(-Delta)(s) u - lambda u=f (x, u) in Omega u=0 in R-n backslash Omega.

Thus, the results presented here may be seen as the extension of some classical nonlinear analysis theorems to the case of fractional operators.

来源出版物: Discrete and Continuous Dynamical Systems, 2013, 33(5): 2105–2137联系邮箱: Servadei, R; servadei@mat.unical.it

被引频次: 25

Mathematical Theory and Numerical Methods for Bose-Einstein Condensation

Bao, WZ; Cai, YY

Abstract: In this paper, we mainly review recent results on mathematical theory and numerical methods for Bose-Einstein condensation (BEC), based on the Gross-Pitaevskii equation (GPE). Starting from the simplest case with one-component BEC of the weakly interacting bosons, we study the reduction of GPE to lower dimensions, the ground states of BEC including the existence and uniqueness as well as nonexistence results, and the dynamics of GPE including dynamical laws, well-posedness of the Cauchy problem as well as the finite time blow-up. To compute the ground state, the gradient flow with discrete normalization (or imaginary time) method is reviewed and various full discretization methods are presented and compared. To simulate the dynamics, both finite difference methods and time splitting spectral methods are reviewed, and their error estimates are briefly outlined. When the GPE has symmetric properties, we show how to simplify the numerical methods. Then we compare two widely used scalings, i.e. physical scaling (commonly used) and semiclassical scaling, for BEC in strong repulsive interaction regime (Thomas-Fermi regime), and discuss semiclassical limits of the GPE. Extensions of these results for one-component BEC are then carried out for rotating BEC by GPE with an angular momentum rotation, dipolar BEC by GPE with long range dipole-dipole interaction, and two-component BEC by coupled GPEs. Finally, as a perspective, we show briefly the mathematical models for spin-1 BEC, Bogoliubov excitation and BEC at finite temperature.

Keywords: nonlinear schrodinger-equation; gross-pitaevskii equation; central vortex states; splitting spectral approximations; hermite pseudospectral method; finite-difference methods; optimal partition problem; normalized gradient flow; computing ground-states; dipolar quantum gases

来源出版物: Kinetic and Related Models, 2013, 6(1): 1–135联系邮箱: Bao, WZ; bao@math.nus.edu.sg

被引频次: 22

Remarks on some coupled fixed point theorems in G-metric spaces

Agarwal, RP; Karapinar, E

Abstract: In this paper, we show that, unexpectedly, most of the coupled fixed point theorems in the context of (ordered) G-metric spaces are in fact immediate consequences of usual fixed point theorems that are either well known in the literature or can be obtained easily.

Keywords: mixed monotone mappings; partially ordered sets; nonlinear contractions; coincidence; equations

来源出版物: Fixed Point Theory and Applications, 2013联系邮箱: Karapinar, E; erdalkarapinar@yahoo.com

被引频次: 22

Convergence analysis of an iterative algorithm for monotone operators

Cho, SY; Li, WL; Kang, SM

Abstract: In this paper, an iterative algorithm is proposed to study some nonlinear operators which are inverse-strongly monotone, maximal monotone, and strictly pseudocontractive. Strong convergence of the proposed iterative algorithm is obtained in the framework of Hilbert spaces.

Keywords: fixed-point problems; phi-nonexpansive mappings; hybrid projection methods; equilibrium problems; weak-convergence; common solutions; hilbert-spaces; banach-spaces; theorems; pseudocontractions

来源出版物: Journal of Inequalities and Applications, 2013: 199联系邮箱: Kang, SM; smkang@gnu.ac.kr

MECHANICS 力学

被引频次: 73

Hierarchical multi-innovation stochastic gradient algorithm for Hammerstein nonlinear system modeling

Ding, F

Keywords: squares identification methods; errors-in-variables; dual-rate systems; parameter-estimation; armax systems; accuracy

来源出版物: Applied Mathematical Modelling, 2013, 37(4): 1694–1704联系邮箱: Ding, F; fding@jiangnan.edu.cn

被引频次: 65

A review of the applications of nanofluids in solar energy

Mahian, O; Kianifar, A; Kalogirou, SA; et al.

Abstract: Utilizing nanofluids as an advanced kind of liquid mixture with a small concentration of nanometer-sized solid particles in suspension is a relatively new field, which is less than two decades old. The aim of this review paper is the investigation of the nanofluids' applications in solar thermal engineering systems. The shortage of fossil fuels and environmental considerations motivated the researchers to use alternative energy sources such as solar energy. Therefore, it is essential to enhance the efficiency and performance of the solar thermal systems. Nearly all of the former works conducted on the applications of nanofluids in solar energy is regarding their applications in collectors and solar water heaters. Therefore, a major part of this review paper allocated to the effects of nanofluids on the performance of solar collectors and solar water heaters from the efficiency, economic and environmental considerations viewpoints. In addition, some reported works on the applications of nanofluids in thermal energy storage, solar cells, and solar stills are reviewed. Subsequently, some suggestions are made to use the nanofluids in different solar thermal systems such as photovoltaic/thermal systems, solar ponds, solar thermoelectric cells, and so on. Finally, the challenges of using nanofluids in solar energy devices are discussed.

Keywords: nanohorn-based nanofluids; radiation-enhanced evaporation; heat-transfer characteristics; thermal-conductivity; cooling system; metal nanoparticles; optical-properties; forced-convection; economic-analysis; particle-size

来源出版物: International Journal of Heat and Mass Transfer, 2013, 57(2): 582–594联系邮箱: Pop, I; popm.ioan@yahoo.co.uk

被引频次: 55

Two-stage least squares based iterative estimation algorithm for CARARMA system modeling

Ding, F

Abstract: For stochastic systems described by the controlled autoregressive autoregressive moving average (CARARMA) models, a new-type two-stage least squares based iterative algorithm is proposed for identifying the system model parameters and the noise model parameters. The basic idea is based on the interactive estimation theory and to estimate the parameter vectors of the system model and the noise model, respectively. The simulation results indicate that the proposed algorithm is effective.

来源出版物: Applied Mathematical Modelling, 2013, 37(7): 4798–4808联系邮箱: Ding, F; fding@jiangnan.edu.cn

被引频次: 50

Grain boundaries as the controlling factor for the ferromagnetic behaviour of Co-doped ZnO

Straumal, BB; Mazilkin, AA; Protasova, SG; et al.

Abstract: The influence of the grain boundary (GB) specific area s(GB) on the appearance of ferromagnetism in Co-doped ZnO has been analysed based on a review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Co-doped ZnO. An empirical correlation has been found that the value of the specific grain boundary area s(GB) is the main factor controlling such behaviour. The Co-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if s(GB) is higher than a certain threshold value s(th)=1.5×106m2/m3. It corresponds to the effective grain size of about 1 mu m assuming a full dense material and equiaxial grains. The magnetic properties of Co-doped (0 to 42 at. %) ZnO dense nanograined thin films have been investigated. The films were deposited using the wet chemistry liquid ceramics method. The samples demonstrate ferromagnetic behaviour with J(s) up to 0.12 emu/g and coercivity H-c approximate to 0.01T. Saturation magnetization non-monotonically depends on the Co concentration. The dependence on Co content can be explained by the changes in the structure of a ferromagnetic grain boundary foam responsible for the magnetic properties of pure and doped ZnO.

Keywords: room-temperature ferromagnetism; zn1-xcoxo thin-films; diluted magnetic semiconductors; chemical-vapor-deposition; optical-properties; zinc-oxide; electrochemical deposition; substituted zno; nanorods; nanocrystals

来源出版物: Philosophical Magazine, 2013, 93(10-12): 1371–1383联系邮箱: Straumal, BB; straumal@mf.mpg.de

被引频次: 49

Entropy generation in steady MHD flow due to a rotating porous disk in a nanofluid

Rashidi, MM; Abelman, S; Mehr, NF

Abstract: We consider the analysis of the second law of thermodynamics applied to an electrically conducting incompressible nanofluid fluid flowing over a porous rotating disk in the presence of an externally applied uniform vertical magnetic field. This study has applications in rotating magneto-hydrodynamic (MHD) energy generators for new space systems and also thermal conversion mechanisms fornuclear propulsion space vehicles. Von Karman transformations are employed to transform the governing equations into a system of nonlinear ordinary differential equations. The entropy generation equation is derived as a function of velocity and temperature gradient. This equation is non-dimensionalized using geometrical and physical flow field-dependent parameters. The velocity profiles in radial, tangential and axial directions, temperature distribution, averaged entropy generation number and Bejan number are obtained. A very good agreement is observed between the obtained results of the current study and those of previously published studies. The effects of physical flow parameters such as magnetic interaction parameter, suction parameter, nanoparticle volume fraction and the type of nanofluid on all fluid velocity components, temperature distribution, averaged entropy generation number and Bejan number, skin friction coefficient and Nusselt number are examined and analyzed and the path for optimizing the entropy is also proposed. In addition, this simulation represents the feasibility of using magnetic rotating disk drives in novel nuclear space propulsion engines and this model has important applications in heat transfer enhancement in renewable energy systems and industrial thermal management.

Keywords: heat-transfer characteristics; stretching sheet; mass-transfer; convection; particles

来源出版物: International Journal of Heat and Mass Transfer, 2013, 62: 515–525联系邮箱: Rashidi, MM; mm.rashidi@usherbrooke.ca

MEDICAL INFORMATICS 医学信息

被引频次: 45

Evidence Synthesis for Decision Making 2: A Generalized Linear Modeling Framework for Pairwise and Network Meta-analysis of Randomized Controlled Trials

Dias, S; Sutton, AJ; Ades, AE; et al.

Abstract: We set out a generalized linear model framework for the synthesis of data from randomized controlled trials. A common model is described, taking the form of a linear regression for both fixed and random effects synthesis, which can be implemented with normal, binomial, Poisson, and multinomial data. The familiar logistic model for meta-analysis with binomial data is a generalized linear model with a logit link function, which is appropriate for probability outcomes. The same linear regression framework can be applied to continuous outcomes, rate models, competing risks, or ordered category outcomes by using other link functions, such as identity, log, complementary log-log, and probit link functions. The common core model for the linear predictor can be applied to pairwise meta-analysis, indirect comparisons, synthesis of multiarm trials, and mixed treatment comparisons, also known as network meta-analysis, without distinction. We take a Bayesian approach to estimation and provide WinBUGS program code for a Bayesian analysis using Markov chain Monte Carlo simulation. An advantage of this approach is that it is straightforward to extend to shared parameter models where different randomized controlled trials report outcomes in different formats but from a common underlying model. Use of the generalized linear model framework allows us to present a unified account of how models can be compared using the deviance information criterion and how goodness of fit can be assessed using the residual deviance. The approach is illustrated through a range of worked examples for commonly encountered evidence formats.

Keywords: mixed treatment comparisons; clinical-trials; binary outcomes; consistency; tables

来源出版物: Medical Decision Making, 2013, 33(5): 607–617联系邮箱: Dias, S; s.dias@bristol.ac.uk

被引频次: 40

Social contagion theory: examining dynamic social networks and human behavior

Christakis, NA; Fowler, JH

Abstract: Here, we review the research we have conducted on social contagion. We describe the methods we have employed (and the assumptions they have entailed) to examine several datasets with complementary strengths and weaknesses, including the Framingham Heart Study, the National Longitudinal Study of Adolescent Health, and other observational and experimental datasets that we and others have collected. We describe the regularities that led us to propose that human social networks may exhibit a three degrees of influence property, and we review statistical approaches we have used to characterize interpersonal influence with respect to phenomena as diverse as obesity, smoking, cooperation, and happiness. We do not claim that this work is the final word, but we do believe that it provides some novel, informative, and stimulating evidence regarding social contagion in longitudinally followed networks. Along with other scholars, we are working to develop new methods for identifying causal effects using social network data, and we believe that this area is ripe for statistical development as current methods have known and often unavoidable limitations.

Keywords: cosponsorship networks; sensitivity-analysis; friendship networks; adolescent smoking; randomized-trial; peer influence; supreme-court; spread; selection; time

来源出版物: Statistics in Medicine, 2013, 32(4): 556–577联系邮箱: Christakis, NA; christakis@hcp.med.harvard.edu

被引频次: 29

Web-scale pharmacovigilance: listening to signals from the crowd

White, RW; Tatonetti, NP; Shah, NH; et al.

Abstract: Adverse drug events cause substantial morbidity and mortality and are often discovered after a drug comes to market. We hy-pothesized that Internet users may provide early clues about adverse drug events via their online information-seeking. We conducted a large-scale study of Web search log data gathered during 2010. We pay particular attention to the specific drug pairing of paroxetine and pravastatin, whose interaction was reported to cause hyperglycemia after the time period of the online logs used in the analysis. We also examine sets of drug pairs known to be associated with hyperglycemia and those not associated with hyperglycemia. We find that anonymized signals on drug interactions can be mined from search logs. Compared to analyses of other sources such as electronic health records (EHR), logs are inexpensive to collect and mine. The results demonstrate that logs of the search activities of populations of computer users can contribute to drug safety surveillance.

Keywords: adverse events; drug

来源出版物: Journal of The American Medical Informatics Association, 2013, 20(3): 404–408

联系邮箱: White, RW; ryenw@microsoft.com

被引频次: 29

Next-generation phenotyping of electronic health records

Hripcsak, G; Albers, DJ

Abstract: The national adoption of electronic health records (EHR) promises to make an unprecedented amount of data available for clinical research, but the data are complex, inaccurate, and frequently missing, and the record reflects complex processes aside from the patient's physiological state. We believe that the path forward requires studying the EHR as an object of interest in itself, and that new models, learning from data, and collaboration will lead to efficient use of the valuable information currently locked in health records.

Keywords: community-acquired pneumonia; medical-records; time-series; risk; classification; identification; information; databases; network; systems

来源出版物: Journal of The American Medical Informatics Association, 2013, 20(1): 117–121

联系邮箱: Hripcsak, G; hripcsak@columbia.edu

被引频次: 27

A New Dimension of Health Care: Systematic Review of the Uses, Benefits, and Limitations of Social Media for Health Communication

Moorhead, SA; Hazlett, DE; Harrison, L; et al.

Abstract: Background: There is currently a lack of information about the uses, benefits, and limitations of social media for health communication among the general public, patients, and health professionals from primary research.

Objective: To review the current published literature to identify the uses, benefits, and limitations of social media for health communication among the general public, patients, and health professionals, and identify current gaps in the literature to provide recommendations for future health communication research.

Methods: This paper is a review using a systematic approach. A systematic search of the literature was conducted using nine electronic databases and manual searches to locate peer-reviewed studies published between January 2002 and February 2012.

Results: The search identified 98 original research studies that included the uses, benefits, and/or limitations of social media for health communication among the general public, patients, and health professionals. The methodological quality of the studies assessed using the Downs and Black instrument was low; this was mainly due to the fact that the vast majority of the studies in this review included limited methodologies and was mainly exploratory and descriptive in nature. Seven main uses of social media for health communication were identified, including focusing on increasing interactions with others, and facilitating, sharing, and obtaining health messages. The six key overarching benefits were identified as (1) increased interactions with others, (2) more available, shared, and tailored information, (3) increased accessibility and widening access to health information, (4) peer/social/emotional support, (5) public health surveillance, and (6) potential to influence health policy. Twelve limitations were identified, primarily consisting of quality concerns and lack of reliability, confidentiality, and privacy.

Conclusions: Social media brings a new dimension to health care as it offers a medium to be used by the public, patients, and health professionals to communicate about health issues with the possibility of potentially improving health outcomes. Social media is a powerful tool, which offers collaboration between users and is a social interaction mechanism for a range of individuals. Although there are several benefits to the use of social media for health communication, the information exchanged needs to be monitored for quality and reliability, and the users' confidentiality and privacy need to be maintained. Eight gaps in the literature and key recommendations for future health communication research were provided. Examples of these recommendations include the need to determine the relative effectiveness of different types of social media for health communication using randomized control trials and to explore potential mechanisms for monitoring and enhancing the quality and reliability of health communication using social media. Further robust and comprehensive evaluation and review, using a range of methodologies, are required to establish whether social media improves health communication practice both in the short and long terms.

Keywords: networking web site; young-adults; information-sources; facebook profiles; drug information; national-survey; internet blogs; peer support; online; patient

来源出版物: Journal of Medical Internet Research, 2013, 15(4):联系邮箱: Moorhead, SA; a.moorhead@ulster.ac.uk

MEDICAL LABORATORY TECHNOLOGY 医学实验室技术

被引频次: 67

Circulating Tumor Cells: Liquid Biopsy of Cancer

Alix-Panabieres, C; Pantel, K

Abstract: BACKGROUND: The detection and molecular characterization of circulating tumor cells (CTCs) are one of the most active areas of translational cancer research, with >400 clinical studies having included CTCs as a biomarker. The aims of research on CTCs include (a) estimation of the risk for metastatic relapse or metastatic progression (prognostic information), (b) stratification and real-time monitoring of therapies, (c) identification of therapeutic targets and resistance mechanisms, and (d) understanding metastasis development in cancer patients.

CONTENT: This review focuses on the technologies used for the enrichment and detection of CTCs. We outline and discuss the current technologies that are based on exploiting the physical and biological properties of CTCs. A number of innovative technologies to improve methods for CTC detection have recently been developed, including CTC microchips, filtration devices, quantitative reverse-transcription PCR assays, and automated microscopy systems. Molecular-characterization studies have indicated, however, that CTCs are very heterogeneous, a finding that underscores the need for multiplex approaches to capture all of the relevant CTC subsets. We therefore emphasize the current challenges of increasing the yield and detection of CTCs that have undergone an epithelial mesenchymal transition. Increasing assay analytical sensitivity may lead, however, to a decrease in analytical specificity (e.g., through the detection of circulating normal epithelial cells).

SUMMARY: A considerable number of promising CTC-detection techniques have been developed in recent years. The analytical specificity and clinical utility of these methods must be demonstrated in large prospective multicenter studies to reach the high level of evidence required for their introduction into clinical practice.

Keywords: metastatic breast-cancer; peripheral-blood; molecular characterization; prostate-cancer; progression; expression; challenges; technology; disease; assay

来源出版物: Clinical Chemistry, 2013, 59(1): 110–118联系邮箱: Pantel, K; pantel@uke.de

被引频次: 52

Molecular Testing Guideline for Selection of Lung Cancer Patients for EGFR and ALK Tyrosine Kinase Inhibitors

Lindeman, NI; Cagle, PT; Beasley, MB; et al.

Abstract: Objective.-To establish evidence-based recommendations for the molecular analysis of lung cancers that are required to guide EGFR- and ALK-directed therapies, addressing which patients and samples should be tested, and when and how testing should be performed.

Participants.-Three cochairs without conflicts of interest were selected, one from each of the 3 sponsoring professional societies: College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Writing and advisory panels were constituted from additional experts from these societies.

Evidence.-Three unbiased literature searches of electronic databases were performed to capture articles published from January 2004 through February 2012, yielding 1533 articles whose abstracts were screened to identify 521 pertinent articles that were then reviewed in detail for their relevance to the recommendations. Evidence was formally graded for each recommendation.

Consensus Process.-Initial recommendations were formulated by the cochairs and panel members at a public meeting. Each guideline section was assigned to at least 2 panelists. Drafts were circulated to the writing panel (version 1), advisory panel (version 2), and the public (version 3) before submission (version 4).

Conclusions.-The 37 guideline items address 14 subjects, including 15 recommendations (evidence grade A/B). The major recommendations are to use testing for EGFR mutations and ALK fusions to guide patient selection for therapy with an epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) inhibitor, respectively, in all patients with advanced-stage adenocarcinoma, regardless of sex, race, smoking history, or other clinical risk factors, and to prioritize EGFR and ALK testing over other molecular predictive tests. As scientific discoveries and clinical practice outpace the completion of randomized clinical trials, evidence-based guidelines developed by expert practitioners are vital for communicating emerging clinical standards. Already, new treatments targeting genetic alterations in other, less common driver oncogenes are being evaluated in lung cancer, and testing for these may be addressed in future versions of these guidelines.

Keywords: epidermal-growth-factor; factor-receptor gene; in-situ-hybridization; polymerase-chain-reaction; mutation-specific antibodies;resolution melting analysis; performance liquid-chromatography; chemotherapy-naive patients; eml4-alk fusion gene; smart-amplification process

来源出版物: Archives of Pathology & Laboratory Medicine, 2013, 137(6): 828–860联系邮箱: Lindeman, NI; nlindeman@partners.org

被引频次: 46

Cancer Genome Scanning in Plasma: Detection of Tumor-Associated Copy Number Aberrations, Single-Nucleotide Variants, and Tumoral Heterogeneity by Massively Parallel Sequencing

Chan, KCA; Jiang, PY; Zheng, YWL; et al.

Abstract: BACKGROUND: Tumor-derived DNA can be found in the plasma of cancer patients. In this study, we explored the use of shotgun massively parallel sequencing (MPS) of plasma DNA from cancer patients to scan a cancer genome noninvasively.

METHODS: Four hepatocellular carcinoma patients and a patient with synchronous breast and ovarian cancers were recruited. DNA was extracted from the tumor tissues, and the preoperative and postoperative plasma samples of these patients were analyzed with shotgun MPS.

RESULTS: We achieved the genomewide profiling of copy number aberrations and point mutations in the plasma of the cancer patients. By detecting and quantifying the genomewide aggregated allelic loss and point mutations, we determined the fractional concentrations of tumor-derived DNA in plasma and correlated these values with tumor size and surgical treatment. We also demonstrated the potential utility of this approach for the analysis of complex oncologic scenarios by studying the patient with 2 synchronous cancers. Through the use of multiregional sequencing of tumoral tissues and shotgun sequencing of plasma DNA, we have shown that plasma DNA sequencing is a valuable approach for studying tumoral heterogeneity.

CONCLUSIONS: Shotgun DNA sequencing of plasma is a potentially powerful tool for cancer detection, monitoring, and research.

Keywords: noninvasive prenatal-diagnosis; fetal chromosomal aneuploidy; maternal plasma; microsatellite alterations; nucleic-acids; digital pcr; serum dna; mutations; evolution

来源出版物: Clinical Chemistry, 2013, 59(1): 211–224联系邮箱: Lo, YMD; loym@cuhk.edu.hk

被引频次: 42

Preanalytical quality improvement: in quality we trust

Lippi, G; Becan-McBride, K; Behulova, D; et al.

Abstract: Total quality in laboratory medicine should be defined as the guarantee that each activity throughout the total testing process is correctly performed, providing valuable medical decision-making and effective patient care. In the past decades, a 10-fold reduction in the analytical error rate has been achieved thanks to improvements in both reliability and standardization of analytical techniques, reagents, and instrumentation. Notable advances in information technology, quality control and quality assurance methods have also assured a valuable contribution for reducing diagnostic errors. Nevertheless, several lines of evidence still suggest that most errors in laboratory diagnostics fall outside the analytical phase, and the pre- and postanalytical steps have been found to be much more vulnerable. This collective paper, which is the logical continuum of the former already published in this journal 2 years ago, provides additional contribution to risk management in the preanalytical phase and is a synopsis of the lectures of the 2nd European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)-Becton Dickinson (BD) European Conference on Preanalytical Phase meeting entitled "Preanalytical quality improvement: in quality we trust" (Zagreb, Croatia, 1-2 March 2013). The leading topics that will be discussed include quality indicators for preanalytical phase, phlebotomy practices for collection of blood gas analysis and pediatric samples, lipemia and blood collection tube interferences, preanalytical requirements of urinalysis, molecular biology hemostasis and platelet testing, as well as indications on best practices for safe blood collection. Auditing of the preanalytical phase by ISO assessors and external quality assessment for preanalytical phase are also discussed.

Keywords: primary-health-care; blood collection tubes; laboratory medicine; hemolysis index; clinical laboratories; patient safety; iso 15189; errors; sample; diagnostics

来源出版物: Clinical Chemistry and Laboratory Medicine, 2013, 51(1): 229–241联系邮箱: Lippi, G; glippi@ao.pr.it

被引频次: 37

Heterogeneity of Epidermal Growth Factor Receptor Status and Mutations of KRAS/PIK3CA in Circulating Tumor Cells of Patients with Colorectal Cancer

Gasch, C; Bauernhofer, T; Pichler, M; et al.

Abstract: BACKGROUND: Molecular characterization of circulating tumor cells (CTCs) is pivotal to increasing the diagnostic specificityof CTC assays and investigating therapeutic targets and their downstream pathways on CTCs. We focused on epidermal growth factor receptor (EGFR) and genes relevant for its inhibition in patients with colorectal cancer (CRC).

METHODS: We used the Cell Search (R) system for CTC detection in peripheral blood samples from 49 patients with metastatic CRC (mCRC) and 32 patients with nonmetastatic CRC (nmCRC). We assessed EGFR expression in 741 CTCs from 27 patients with mCRC and 6 patients with nmCRC using a fluorescein-conjugated antibody with the Cell Search Epithelial Cell Kit. DNA of a single CTC isolated by micromanipulation was propagated by whole-genome amplification and analyzed by quantitative PCR for EGFR gene amplification and sequencing for KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog), BRAF (v-raf murine sarcoma viral oncogene homolog B1), and PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit a) mutations.

RESULTS: At least 2 CTCs were detected in 24 of 49 patients with mCRC and 7 of 32 patients with nmCRC. In 7 of 33 patients, CTCs with increased EGFR expression were identified. Heterogeneity in EGFR expression was observed between CTCs from the same patient. EGFR gene amplification was found in 7 of 26 CTCs from 3 patients. The investigated BRAF gene locus was not mutated in 44 analyzed CTCs, whereas KRAS mutations were detected in 5 of 15 CTCs from 1 patient and PIK3CA mutations in 14 of 36 CTCs from 4 patients. CONCLUSIONS: Molecular characterization of single CTCs demonstrated considerable intra- and interpatient heterogeneity of EGFR expression and genetic alterations in EGFR, KRAS, and PIK3CA, possibly explaining the variable response rates to EGFR inhibition in patients with CRC.

Keywords: breast-cancer; single cells; mesenchymal transition; gene-expression; colon-cancer; egfr; metastases; prognosis; carcinoma; cetuximab

来源出版物: Clinical Chemistry, 2013, 59(1): 252–260联系邮箱: Riethdorf, S; s.riethdorf@uke.uni-hamburg.de

MEDICINE GENERAL INTERNAL 内科学

被引频次: 467

Human Infection with a Novel Avian-Origin Influenza A (H7N9) Virus

Gao, RB; Cao, B; Hu, YW; et al.

Abstract: BACKGROUND Infection of poultry with influenza A subtype H7 viruses occurs worldwide, but the introduction of this subtype to humans in Asia has not been observed previously. In March 2013, three urban residents of Shanghai or Anhui, China, presented with rapidly progressing lower respiratory tract infections and were found to be infected with a novel reassortant avian-origin influenza A (H7N9) virus.

METHODS We obtained and analyzed clinical, epidemiologic, and virologic data from these patients. Respiratory specimens were tested for influenza and other respiratory viruses by means of real-time reverse-transcriptase-polymerase-chain-reaction assays, viral culturing, and sequence analyses.

RESULTS A novel reassortant avian-origin influenza A (H7N9) virus was isolated from respiratory specimens obtained from all three patients and was identified as H7N9. Sequencing analyses revealed that all the genes from these three viruses were of avian origin, with six internal genes from avian influenza A (H9N2) viruses. Substitution Q226L (H3 numbering) at the 210-loop in the hemagglutinin (HA) gene was found in the A/Anhui/1/2013 and A/Shanghai/2/2013 virus but not in the A/Shanghai/1/2013 virus. A T160A mutation was identified at the 150-loop in the HA gene of all three viruses. A deletion of five amino acids in the neuraminidase (NA) stalk region was found in all three viruses. All three patients presented with fever, cough, and dyspnea. Two of the patients had a history of recent exposure to poultry. Chest radiography revealed diffuse opacities and consolidation. Complications included acute respiratory distress syndrome and multiorgan failure. All three patients died.

CONCLUSIONS Novel reassortant H7N9 viruses were associated with severe and fatal respiratory disease in three patients. (Funded by the National Basic Research Program of China and others.)

Keywords: british-columbia; H5N1; transmission; hemagglutinin; chickens; outbreak; ferrets

来源出版物: New England Journal of Medicine, 2013, 368(20): 1888–1897联系邮箱: Shu, YL; zhyuan@shmu.edu.cn

被引频次: 423

Primary Prevention of Cardiovascular Disease with a Mediterranean Diet

Estruch, R; Ros, E; Salas-Salvado, J; et al.

Abstract: BACKGROUND Observational cohort studies and a secondary prevention trial have shown an inverse association between adherence to the Mediterranean diet and cardiovascular risk. We conducted a randomized trial of this diet pattern for the primary prevention of cardiovascular events.

METHODS In a multicenter trial in Spain, we randomly assigned participants who were at high cardiovascular risk, but with no cardiovas-cular disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat). Participants received quarterly individual and group educational sessions and, depending on group assignment, free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary end point was the rate of major cardiovascular events (myocardial infarction, stroke, or death from cardiovascular causes). On the basis of the results of an interim analysis, the trial was stopped after a median follow-up of 4.8 years.

RESULTS A total of 7447 persons were enrolled (age range, 55 to 80 years); 57% were women. The two Mediterranean-diet groups had good adherence to the intervention, according to self-reported intake and biomarker analyses. A primary end-point event occurred in 288 participants. The multivariable-adjusted hazard ratios were 0.70 (95% confidence interval [CI], 0.54 to 0.92) and 0.72 (95% CI, 0.54 to 0.96) for the group assigned to a Mediterranean diet with extra-virgin olive oil (96 events) and the group assigned to a Mediterranean diet with nuts (83 events), respectively, versus the control group (109 events). No diet-related adverse effects were reported.

CONCLUSIONS Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.

Keywords: coronary-heart-disease; olive oil intake; randomized-trial; metabolic syndrome; risk-factors; prospective cohort; style diet; adherence; intervention; nutrition

来源出版物: New England Journal of Medicine, 2013, 368(14): 1279–1290联系邮箱: Estruch, R; restruch@clinic.ub.es

被引频次: 323

Nivolumab plus Ipilimumab in Advanced Melanoma

Wolchok, JD; Kluger, H; Callahan, MK; et al.

Abstract: BACKGROUND In patients with melanoma, ipilimumab (an antibody against cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4]) prolongs overall survival, and nivolumab (an antibody against the programmed death 1 [PD-1] receptor) produced durable tumor regression in a phase 1 trial. On the basis of their distinct immunologic mechanisms of action and supportive preclinical data, we conducted a phase 1 trial of nivolumab combined with ipilimumab in patients with advanced melanoma.

METHODS We administered intravenous doses of nivolumab and ipilimumab in patients every 3 weeks for 4 doses, followed by nivolumab alone every 3 weeks for 4 doses (concurrent regimen). The combined treatment was subsequently administered every 12 weeks for up to 8 doses. In a sequenced regimen, patients previously treated with ipilimumab received nivolumab every 2 weeks for up to 48 doses.

RESULTS A total of 53 patients received concurrent therapy with nivolumab and ipilimumab, and 33 received sequenced treatment. The objective-response rate (according to modified World Health Organization criteria) for all patients in the concurrent-regimen group was 40%. Evidence of clinical activity (conventional, unconfirmed, or immune-related response or stable disease for≥24 weeks) was observed in 65% of patients. At the maximum doses that were associated with an acceptable level of adverse events (nivolumab at a dose of 1 mg per kilogram of body weight and ipilimumab at a dose of 3 mg per kilogram), 53% of patients had an objective response, all with tumor reduction of 80% or more. Grade 3 or 4 adverse events related to therapy occurred in 53% of patients in the concurrent-regimen group but were qualitatively similar to previous experience with monotherapy and were generally reversible. Among patients in the sequenced-regimen group, 18% had grade 3 or 4 adverse events related to therapy and the objective-response rate was 20%.

CONCLUSIONS Concurrent therapy with nivolumab and ipilimumab had a manageable safety profile and provided clinical activity that appears to be distinct from that in published data on monotherapy, with rapid and deep tumor regression in a substantial proportion of patients.

Keywords: anti-pd-1 antibody; response criteria; cancer; safety; tumors; survival; therapy; ctla-4; pd-1

来源出版物: New England Journal of Medicine, 2013, 369(2): 122–133联系邮箱: Wolchok, JD; wolchokj@mskcc.org

被引频次: 308

Association of All-Cause Mortality With Overweight and Obesity Using Standard Body Mass Index Categories A Systematic Review and Meta-analysis

Flegal, KM; Kit, BK; Orpana, H; et al.

Abstract: Importance Estimates of the relative mortality risks associated with normal weight, overweight, and obesity may help to inform decision making in the clinical setting.

Objective To perform a systematic review of reported hazard ratios (HRs) of all-cause mortality for overweight and obesity relative to normal weight in the general population.

Data Sources PubMed and EMBASE electronic databases were searched through September 30, 2012, without language restrictions.

Study Selection Articles that reported HRs for all-cause mortality using standard body mass index (BMI) categories from prospective stu-dies of general populations of adults were selected by consensus among multiple reviewers. Studies were excluded that used nonstandard categories or that were limited to adolescents or to those with specific medical conditions or to those undergoing specific procedures. PubMed searches yielded 7034 articles, of which 141 (2.0%) were eligible. An EMBASE search yielded 2 additional articles. After eliminating overlap, 97 studies were retained for analysis, providing a combined sample size of more than 2.88 million individuals and more than 270000 deaths.

Data Extraction Data were extracted by 1 reviewer and then reviewed by 3 independent reviewers. We selected the most complex model available for the full sample and used a variety of sensitivity analyses to address issues of possible overadjustment (adjusted for factors in causal pathway) or underadjustment (not adjusted for at least age, sex, and smoking).

Results Random-effects summary all-cause mortality HRs for overweight (BMI of 25-<30), obesity (BMI o≥30), grade 1 obesity (BMI of 30-<35), and grades 2 and 3 obesity (BMI of≥35) were calculated relative to normal weight (BMI of 18.5-<25). The summary HRs were 0.94 (95% CI, 0.91-0.96) for overweight, 1.18 (95% CI, 1.12-1.25) for obesity (all grades combined), 0.95 (95% CI, 0.88-1.01) for grade 1 obesity, and 1.29 (95% CI, 1.18-1.41) for grades 2 and 3 obesity. These findings persisted when limited to studies with measured weight and height that were considered to be adequately adjusted. The HRs tended to be higher when weight and height were self-reported rather than measured.

Conclusions and Relevance Relative to normal weight, both obesity (all grades) and grades 2 and 3 obesity were associated with significantly higher all-cause mortality. Grade 1 obesity overall was not associated with higher mortality, and overweight was associated with significantly lower all-cause mortality. The use of predefined standard BMI groupings can facilitate between-study comparisons.

Keywords: long-term mortality; cardiovascular-disease mortality; coronary-artery-disease; dwelling older-adults; self-reported weight; middle-aged men; follow-up; risk-factors; life-style; prospective cohort

来源出版物: JAMA-Journal of the American Medical Association, 2013, 309(1): 71–82联系邮箱: Flegal, KM; kmf2@cdc.gov

被引频次: 289

Abiraterone in Metastatic Prostate Cancer without Previous Chemotherapy

Ryan, CJ; Smith, MR; de Bono, JS; et al.

Abstract: BACKGROUND Abiraterone acetate, an androgen biosynthesis inhibitor, improves overall survival in patients with metastatic castration-resistant prostate cancer after chemotherapy. We evaluated this agent in patients who had not received previous chemotherapy.

METHODS In this double-blind study, we randomly assigned 1088 patients to receive abiraterone acetate (1000 mg) plus prednisone (5 mg twice daily) or placebo plus prednisone. The coprimary end points were radiographic progression-free survival and overall survival.

RESULTS The study was unblinded after a planned interim analysis that was performed after 43% of the expected deaths had occurred. The median radiographic progression-free survival was 16.5 months with abiraterone-prednisone and 8.3 months with prednisone alone (hazard ratio for abiraterone-prednisone vs. prednisone alone, 0.53; 95% confidence interval [CI], 0.45 to 0.62; P<0.001). Over a median follow-up period of 22.2 months, overall survival was improved with abiraterone-prednisone (median not reached, vs. 27.2 months for prednisone alone; hazard ratio, 0.75; 95% CI, 0.61 to 0.93; P=0.01) but did not cross the efficacy boundary. Abiraterone-prednisone showed superiority over prednisone alone with respect to time to initiation of cytotoxic chemotherapy, opiate use for cancer-related pain, prostate-specific antigen progression, and decline in performance status. Grade 3 or 4 mineralocorticoid- related adverse events and abnormalities on liver-function testing were more common with abiraterone-prednisone.

CONCLUSIONS Abiraterone improved radiographic progression-free survival, showed a trend toward improved overall survival, and significantly delayed clinical decline and initiation of chemotherapy in patients with metastatic castration-resistant prostate cancer.

Keywords: human cytochrome p450(17-alpha); steroidal inhibitors; hormonal-therapy; controlled trial; clinical-trials; end-points; acetate; carcinoma; mitoxantrone; prednisone

来源出版物: New England Journal of Medicine, 2013, 368(2): 138–148联系邮箱: Ryan, CJ; ryanc@medicine.ucsf.edu

MEDICINE LEGAL 法医学

被引频次: 30

The HIrisPlex system for simultaneous prediction of hair and eye colour from DNA

Walsh, S; Liu, F; Wollstein, A; et al.

Abstract: Recently, the field of predicting phenotypes of externally visible characteristics (EVCs) from DNA genotypes with the final aim of concentrating police investigations to find persons completely unknown to investigating authorities, also referred to as Forensic DNA Phenotyping (FDP), has started to become established in forensic biology. We previously developed and forensically validated the IrisPlex system for accurate prediction of blue and brown eye colour from DNA, and recently showed that all major hair colour categories are pre-dictable from carefully selected DNA markers. Here, we introduce the newly developed HIrisPlex system, which is capable of simultaneously predicting both hair and eye colour from DNA. HIrisPlex consists of a single multiplex assay targeting 24 eye and hair colour predictive DNA variants including all 6 IrisPlex SNPs, as well as two prediction models, a newly developed model for hair colour categories and shade, and the previously developed IrisPlex model for eye colour. The HIrisPlex assay was designed to cope with low amounts of template DNA, as well as degraded DNA, and preliminary sensitivity testing revealed full DNA profiles down to 63 pg input DNA. The power of the HIrisPlex system to predict hair colour was assessed in 1551 individuals from three different parts of Europe showing different hair colour frequencies. Using a 20% subset of individuals, while 80% were used for model building, the individual-based prediction accuracies employing a prediction-guided approach were 69.5% for blond, 78.5% for brown, 80% for red and 87.5% for black hair colour on average. Results from HIrisPlex analysis on worldwide DNA samples imply that HIrisPlex hair colour prediction is reliable independent of bio-geographic ancestry (similar to previous IrisPlex findings for eye colour). We furthermore demonstrate that it is possible to infer with a prediction accuracy of > 86% if a brown-eyed, black-haired individual is of non-European (excluding regions nearby Europe) versus European (including nearby regions) bio-geographic origin solely from the strength of HIrisPlex eye and hair colour probabilities, which can provide extra intelligence for future forensic applications. The HIrisPlex system introduced here, including a single multiplex test assay, an interactive tool and prediction guide, and recommendations for reporting final outcomes, represents the first tool for simultaneously establishing categorical eye and hair colour of a person from DNA. The practical forensic application of the HIrisPlex system is expected to benefit cases where other avenues of investigation, including STR profiling, provide no leads on who the unknown crime scene sample donor or the unknown missing person might be.

Keywords: single nucleotide polymorphisms; human pigmentation; genetic-determinants; skin pigmentation; human-populations; receptor gene; human height; mc1r gene; red hair; association

来源出版物: Forensic Science International-genetics, 2013, 7(1): 98–115联系邮箱: Kayser, M; m.kayser@erasmusmc.nl

被引频次: 29

URB-754: A new class of designer drug and 12 synthetic cannabinoids detected in illegal products

Uchiyama, N; Kawamura, M; Kikura-Hanajiri, R; et al.

Abstract: URB-754 (6-methyl-2-[(4-methylphenyl)amino]-1-benzoxazin-4-one) was identified as a new type of designer drug in illegal products. Though many of the synthetic cannabinoids detected in illegal products are known to have affinities for cannabinoid CB1/CB2 receptors, URB-754 was reported to inhibit an endocannabinoid deactivating enzyme. Furthermore, an unknown compound (N,5-dimethyl-N-(1-oxo1-(p-tolyl)butan-2-yl)-2-(N'-(p-tolyl)ureido)benzamide), which is deduced to be the product of a reaction between URB-754 and a cathinone derivative 4-methylbuphedrone (4-Me-MABP), was identified along with URB-754 and 4-Me-MABP in the same product. It is of interest that the product of a reaction between two different types of designer drugs, namely, a cannabinoid-related designer drug and a cathinone-type designer drug, was found in one illegal product. In addition, 12 cannabimimetic compounds, 5-fluoropentyl-3-pyridinoylindole, JWH-307, JWH-030, UR-144, 5FUR-144 (synonym: XLR11), (4-methylnaphtyl)-JWH-022 [synonym: N-(5-fluoropentyl)-JWH-122],AM-2232,(4-methylnaphtyl)-AM-2201(MAM-2201),N-(4-pentenyl)-JWH-122,JWH-213, (4-ethylnaphtyl)-AM-2201 (EAM-2201) and AB-001, were also detected herein as newly distributed designer drugs in Japan. Furthermore, a tryptamine derivative, 4-hydroxy-diethyltryptamine (4-OH-DET), was detected together with a synthetic cannabinoid, APINACA, in the same product.

Keywords: cannabimimetic indoles; receptor agonists; herbal product; CB2 receptors; identification; hydrolysis; 2-ag

来源出版物: Forensic Science International, 2013, 227(1-3): 21–32联系邮箱: Goda, Y; goda@nihs.go.jp

被引频次: 24

Carbonic anhydrase inhibitors: an editorial

Supuran, CT

Abstract: This issue of Expert Opinion on Therapeutic Patents is dedicated to carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs), a highly dynamic research topic in the last years. Several review articles and patent analyses on diuretics and antiglaucoma, antiepileptic, anti-obesity and anticancer agents belonging to the pharmacological class of the CAIs are presented, together with a review on bacterial, fungal and protozoan CAs and their inhibition as a novel means of designing anti-infectives.

Keywords: sulfonamides; cloning; potent; honey

来源出版物: Expert Opinion on Therapeutic Patents, 2013, 23(6): 677–679联系邮箱: Supuran, CT; claudiu.supuran@unifi.it

被引频次: 23

Anti-infective carbonic anhydrase inhibitors: a patent and literature review

Capasso, C; Supuran, CT

Abstract: Introduction: All microorganisms that cause diseases or illnesses to their host are defined as pathogens. In this paper we will review the current state of the art for inhibiting parasite carbonic anhydrases (CAs, EC 4.2.1.1) with a goal of developing antibacterial, antifungal or antiprotozoan agents possessing a different mechanism of action compared with the clinically used drugs to which a considerable degree of drug resistance has been reported.

Areas covered: Cloning of the genomes of many pathogenic microorganisms offered the possibility of exploring alternative pathways for inhibiting virulence factors or proteins essential for their life cycle, and such an approach was applied systematically for CAs from prokaryotic and eukaryotic microorganisms. Investigations of CAs in bacteria, fungi and protozoa domains will undoubtedly reveal novel aspects of microbial virulence, these efforts being part of a more general approach of using metalloenzyme inhibitors for designing novel classes of anti-infectives.

Expert opinion: Covers an overview of the patent literature in the field of the anti-infective CA inhibitors. Most of the patents deal with sulfonamide CA inhibitors. Bacterial/fungal/protozoan CAs represent at this moment very promising targets for obtaining anti-infectives devoid of the resistance problems of the clinically used such agents but further studies are needed to validate these and other less investigated enzymes as novel drug targets.

Keywords: beta-class enzyme; sulfurihydrogenibium-yellowstonense yo3aop1; yeast saccharomyces-cerevisiae; pathogens candida-albicans; mycobacterium-tuberculosis; cryptococcus-neoformans; plasmodium-falciparum; helicobacter-pylori; molecular-cloning; virulence factors

来源出版物: Expert Opinion on Therapeutic Patents, 2013, 23(6): 693–704联系邮箱: Capasso, C; c.capasso@ibp.cnr.it

被引频次: 21

Designer cathinones-An emerging class of novel recreational drugs

Zawilska, JB; Wojcieszak, J

Abstract: A new group of recreational drugs, popularly known as "bath salts", "plant feeders" or "plant food", has recently emerged in numerous countries. Although various products are labeled with warnings "not for human consumption" or "not tested for hazards or toxicity", they are intended to produce a high similar to that obtained with illegal stimulants, such as MDMA, methamphetamine or cocaine. The active compounds in "bath salts'' are cathinone derivatives continuously developed and modified by drug designers to avoid detection or legal scrutiny. Around 2010 the most prevalent were mephedrone (4-methylmethcathinone) and MDPV (3,4- methylenedioxypyrovalerone). This review surveys the current state of knowledge regarding the pharmacotoxicological properties of synthetic cathinones, the prevalence and pattern of their use. Special emphasis is given to the negative consequences of using these products including, among others, cardiovascular, psychiatric and neurologic symptoms, dehydration, rhambdomyolysis, renal and liver failure. Case reports on synthetic cathinones-related fatalities are also presented.

Keywords: human liver-microsomes; delirium following use; bath salts; legal highs; mephedrone 4-methylmethcathinone; synthetic cathinones; case series; monoamine transporters; psychoactive-drugs; toxicity

来源出版物: Forensic Science International, 2013, 231(1-3): 42–53联系邮箱: Zawilska, JB; jolanta.zawilska@umed.lodz.pl

MEDICINE RESEARCH EXPERIMENTAL 医学实验研究

被引频次: 147

Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis

Koeth, RA; Wang, ZE; Levison, BS; et al.

Abstract: Intestinal microbiota metabolism of choline and phosphatidylcholine produces trimethylamine (MA), which is further metabolized to a proatherogenic species, trimethylamine-N-oxide (TMAO). We demonstrate here that metabolism by intestinal microbiota of dietary L-carnitine, a trimethylamine abundant in red meat, also produces TMAO and accelerates atherosclerosis in mice. Omnivorous human subjects produced more TMAO than did vegans or vegetarians following ingestion of L-carnitine through a microbiota-dependent mechanism. The presence of specific bacterial taxa in human feces was associated with both plasma TMAO concentration and dietary status. Plasma L-carnitine levels in subjects undergoing cardiac evaluation (n=2595) predicted increased risks for both prevalent cardiovascular disease (CVD) and incident major adverse cardiac events (myocardial infarction, stroke or death), but only among subjects with concurrently high TMAO levels. Chronic dietary L-carnitine supplementation in mice altered cecal microbial composition, markedly enhanced synthesis of TMA and TMAO, and increased atherosclerosis, but this did not occur if intestinal microbiota was concurrently suppressed. In mice with an intact intestinal microbiota, dietary supplementation with TMAO or either carnitine or choline reduced in vivo reverse cholesterol trans-port. Intestinal microbiota may thus contribute to the well-established link between high levels of red meat consumption and CVD risk.

Keywords: reverse cholesterol transport; coronary-heart-disease; bile-acid; cardiovascular-disease; gut microbiome; mice; expression; diet; receptors; protein

来源出版物: Nature Medicine, 2013, 19(5): 576–585联系邮箱: Hazen, SL; hazens@ccf.org

被引频次: 140

ABT-199, a potent and selective BCL-2 inhibitor, achieves antitumor activity while sparing platelets

Souers, AJ; Leverson, JD; Boghaert, ER; et al.

Abstract: Proteins in the B cell CLL/lymphoma 2 (BCL-2) family are key regulators of the apoptotic process. This family comprises proapoptotic and prosurvival proteins, and shifting the balance toward the latter is an established mechanism whereby cancer cells evade apoptosis. The therapeutic potential of directly inhibiting prosurvival proteins was unveiled with the development of navitoclax, a selective inhibitor of both BCL-2 and BCL-2-like 1 (BCL-X-L), which has shown clinical efficacy in some BCL-2-dependent hematological cancers. However, concomitant on-target thrombocytopenia caused by BCL-X-L inhibition limits the efficacy achievable with this agent. Here we report the re-engineering of navitoclax to create a highly potent, orally bioavailable and BCL-2-selective inhibitor, ABT-199. This compound inhibits the growth of BCL-2-dependent tumors in vivo and spares human platelets. A single dose of ABT-199 in three patients with refractory chronic lymphocytic leukemia resulted in tumor lysis within 24 h. These data indicate that selective pharmacological inhibition of BCL-2 shows promise for the treatment of BCL-2-dependent hematological cancers.

Keywords: b-cell lymphoma; chronic lymphocytic-leukemia; acute lymphoblastic-leukemia; non-hodgkins-lymphoma; family inhibitor; induce apoptosis; high-affinity; in-vivo; expression; cancer

来源出版物: Nature Medicine, 2013, 19(2): 202–208联系邮箱: Souers, AJ; andrew.souers@abbvie.com

被引频次: 118

The meaning, the sense and the significance: translating the science of mesenchymal stem cells into medicine

Bianco, P; Cao, X; Frenette, PS; et al.

Abstract: Mesenchymal stem cells (MSCs) are the focus of intensive efforts worldwide directed not only at elucidating their nature and unique properties but also developing cell-based therapies for a diverse range of diseases. More than three decades have passed since the original formulation of the concept, revolutionary at the time, that multiple connective tissues could emanate from a common progenitor or stem cell retained in the postnatal bone marrow. Despite the many important advances made since that time, substantial ambiguities still plague the field regarding the nature, identity, function, mode of isolation and experimental handling of MSCs. These uncertainties have a major impact on their envisioned therapeutic use.

Keywords: bone-marrow; hematopoietic stem; osteogenesis imperfecta; progenitor cells; stromal cells; osteoblast differentiation; stem/progenitor cells; fibrous dysplasia; niche; adult

来源出版物: Nature Medicine, 2013, 19(1): 35–42联系邮箱: Bianco, P; paolo.bianco@uniroma1.it

被引频次: 105

WNT signaling in bone homeostasis and disease: from human mutations to treatments

Baron, R; Kneissel, M

Abstract: Low bone mass and strength lead to fragility fractures, for example, in elderly individuals affected by osteoporosis or children with osteogenesis imperfecta. A decade ago, rare human mutations affecting bone negatively (osteoporosis-pseudoglioma syndrome) or positively (high bone mass phenotype, sclerosteosis and Van Buchem disease) have been identified and found to all reside in components of the canonical WNT signaling machinery. Mouse genetics confirmed the importance of canonical Wnt signaling in the regulation of bone homeostasis, with activation of the pathway leading to increased, and inhibition leading to decreased, bone mass and strength. The importance of WNT signaling for bone has also been highlighted since then in the general population in numerous genome-wide association studies. The pathway is now the target for therapeutic intervention to restore bone strength in millions of patients at risk for fracture. This paper reviews our current understanding of the mechanisms by which WNT signalng regulates bone homeostasis.

Keywords: frizzled-related protein-1; osteoporosis-pseudoglioma syndrome; receptor-related protein-5; hematopoietic stem-cells; synovial joint formation; van-buchem-disease; parathyroid-hormone; osteoblast differentiation; beta-catenin; in-vivo

来源出版物: Nature Medicine, 2013, 19(2): 179–192联系邮箱: Baron, R; roland_baron@hsdm.harvard.edu

被引频次: 86

A specific antidote for reversal of anticoagulation by direct and indirect inhibitors of coagulation factor Xa

Lu, GM; DeGuzman, FR; Hollenbach, SJ; et al.

Abstract: Inhibitors of coagulation factor Xa (fXa) have emerged as a new class of antithrombotics but lack effective antidotes for patients experiencing serious bleeding. We designed and expressed a modified form of fXa as an antidote for fXa inhibitors. This recombinant protein (r-Antidote, PRT064445) is catalytically inactive and lacks the membrane-binding gamma-carboxyglutamic acid domain of native fXa but retains the ability of native fXa to bind direct fXa inhibitors as well as low molecular weight heparin-activated antithrombin III (ATIII). r-Antidote dose-dependently reversed the inhibition of fXa by direct fXa inhibitors and corrected the prolongation of ex vivo clotting times by such inhibitors. In rabbits treated with the direct fXa inhibitor rivaroxaban, r-Antidote restored hemostasis in a liver laceration model. The effect of r-Antidote was mediated by reducing plasma anti-fXa activity and the non-protein bound fraction of the fXa inhibitor in plasma. In rats, r-Antidote administration dose-dependently and completely corrected increases in blood loss resulting from ATIII-dependent anticoagulation by enoxaparin or fondaparinux. r-Antidote has the potential to be used as a universal antidote for a broad range of fXa inhibitors.

Keywords: molecular-weight heparin; prothrombin complex concentrate; incomplete reversal; atrial-fibrillation; factor viia; in-vivo; antithrombin; rivaroxaban; protamine; activation

来源出版物: Nature Medicine, 2013, 19(4): 446联系邮箱: Sinha, U; usinha@portola.com

METALLURGY METALLURGICAL ENGINEERING 冶金与冶金工程

被引频次: 95

Extreme grain refinement by severe plastic deformation: A wealth of challenging science

Estrin, Y; Vinogradov, A

Abstract: This article presents our take on the area of bulk ultrafine-grained materials produced by severe plastic deformation (SPD). Over the last decades, research activities in this area have grown enormously and have produced interesting results, which we summarise in this concise review. This paper is intended as an introduction to the field for the "uninitiated", while at the same time highlighting some polemic issues that may be of interest to those specialising in bulk nanomaterials produced by SPD. A brief overview of the available SPD technologies is given, along with a summary of unusual mechanical, physical and other properties achievable by SPD processing. The challenges this research is facing-some of them generic and some specific to the nanoSPD area-are identified and discussed.

Keywords: high-pressure torsion; channel angular extrusion; low-carbon steel; biodegradable magnesium implants; bulk nanostructured materials; commercially pure titanium; stress-corrosion cracking; solid-state infiltration; large-strain deformation; range internal-stresses

来源出版物: Acta Materialia, 2013, 61(3): 782–817联系邮箱: Estrin, Y; yuri.estrin@monash.edu

被引频次: 50

Grain boundaries as the controlling factor for the ferromagnetic behaviour of Co-doped ZnO

Straumal, BB; Mazilkin, AA; Protasova, SG; et al.

来源出版物: Philosophical Magazine, 2013, 93(10-12): 1371–1383联系邮箱: Straumal, BB; straumal@mf.mpg.de

被引频次: 48

Materials challenges in nuclear energy

Zinkle, SJ; Was, GS

Abstract: Nuclear power currently provides about 13% of electrical power worldwide, and has emerged as a reliable baseload source ofelectricity. A number of materials challenges must be successfully resolved for nuclear energy to continue to make further improvements in reliability, safety and economics. The operating environment for materials in current and proposed future nuclear energy systems is summarized, along with a description of materials used for the main operating components. Materials challenges associated with power uprates and extensions of the operating lifetimes of reactors are described. The three major materials challenges for the current and next generation of water-cooled fission reactors are centered on two structural materials aging degradation issues (corrosion and stress corrosion cracking of structural materials and neutron-induced embrittlement of reactor pressure vessels), along with improved fuel system reliability and accident tolerance issues. The major corrosion and stress corrosion cracking degradation mechanisms for light-water reactors are reviewed. The materials degradation issues for the Zr alloy-clad UO2fuel system currently utilized in the majority of commercial nuclear power plants are discussed for normal and off-normal operating conditions. Looking to proposed future (Generation IV) fission and fusion energy systems, there are five key bulk radiation degradation effects (low temperature radiation hardening and embrittlement; radiation-induced and -modified solute segregation and phase stability; irradiation creep; void swelling; and high-temperature helium embrittlement) and a multitude of corrosion and stress corrosion cracking effects (including irradiation-assisted phenomena) that can have a major impact on the performance of structural materials.

Keywords: austenitic stainless-steels; stress-corrosion cracking; ferritic-martensitic steels; low-temperature irradiation; reactor structural-materials; water-reactor; light-water; supercritical water; zirconium alloys; microstructural evolution

来源出版物: Acta Materialia, 2013, 61(3): 735–758联系邮箱: Zinkle, SJ; zinklesj@ornl.gov

被引频次: 43

Superior light metals by texture engineering: Optimized aluminum and magnesium alloys for automotive applications

Hirsch, J; Al-Samman, T

Abstract: Aluminum and magnesium are two highly important lightweight metals used in automotive applications to reduce vehicle weight. Crystallographic texture engineering through a combination of intelligent processing and alloying is a powerful and effective tool to obtain superior aluminum and magnesium alloys with optimized strength and ductility for automotive applications. In the present article the basic mechanisms of texture formation of aluminum and magnesium alloys during wrought processing are described and the major aspects and differences in deformation and recrystallization mechanisms are discussed. In addition to the crystal structure, the resulting properties can vary significantly, depending on the alloy composition and processing conditions, which can cause drastic texture and microstructure changes. The elementary mechanisms of plastic deformation and recrystallization comprising nucleation and growth and their orientation dependence, either within the homogeneously formed microstructure or due to inhomogeneous deformation, are described along with their impact on texture formation, and the resulting forming behavior. The typical face-centered cubic and hexagonal close-packed rolling and recrystallization textures, and related mechanical anisotropy and forming conditions are analyzed and compared for standard aluminum and magnesium alloys. New aspects for their modification and advanced strategies of alloy design and microstructure to improve material properties are derived.

Keywords: high-temperature deformation; dynamic recrystallization; single crystals; rolling textures; hot deformation; sheet metals; AZ31 alloy; mg; behavior; microstructure

来源出版物: Acta Materialia, 2013, 61(3): 818–843联系邮箱: Hirsch, J; Juergen.Hirsch@hydro.com

被引频次: 38

Perspectives on Titanium Science and Technology

Banerjee, D; Williams, JC

Abstract: The basic framework and - conceptual understanding of the metallurgy of Ti alloys is strong and this has enabled the use of titanium and its alloys in safety-critical structures such as those in aircraft and aircraft engines. Nevertheless, a focus on cost-effectiveness and the compression of product development time by effectively integrating design with manufacturing in these applications, as well as those emerging in bioengineering, has driven research in recent decades towards a greater predictive capability through the use of computational materials engineering tools. Therefore this paper focuses on the complexity and variety of fundamental phenomena in this material system with a focus on phase transformations and mechanical behaviour in order to delineate the challenges that lie ahead in achieving these goals.

Keywords: near-alpha-titanium; low youngs modulus; transmission electron-microscopy; dwell-sensitive fatigue; alloy single-crystals; primary hot-working; 2 ductile phases; beta-phase; ti-alloys; texture evolution

来源出版物: Acta Materialia, 2013, 61(3): 844–879联系邮箱: Banerjee, D; dbanerjee@materials.iisc.ernet.in

METEOROLOGY ATMOSPHERIC SCIENCES 气象学与大气科学

被引频次: 247

Bounding the role of black carbon in the climate system: A scientific assessment

Bond, TC; Doherty, SJ; Fahey, DW; et al.

Abstract: Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr-1in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m-2with 90% uncertainty bounds of (+0.08, +1.27) W m-2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m-2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m-2with 90% uncertainty bounds of +0.17 to +2.1 W m-2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m-2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (-0.50 to +1.08) W m-2during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (-0.06 W m-2with 90% uncertainty bounds of -1.45 to +1.29 W m-2).

The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.

Keywords: aerosol light-absorption; general-circulation model; biomass burning emissions; cirrus cloud formation; greenhouse-gas emissions; airborne particulate matter; global warming potentials; indian-ocean experiment; fossil-fuel combustion; chemical mass-balance

来源出版物: Journal of Geophysical Research-Atmospheres, 2013, 118(11): 5380–5552联系邮箱: Bond, TC; yark@uiuc.edu

被引频次: 89

Updated high-resolution grids of monthly climatic observations - the CRU TS3.10 Dataset

Harris, I; Jones, PD; Osborn, TJ; et al.

Abstract: This paper describes the construction of an updated gridded climate dataset (referred to as CRU TS3.10) from monthly observations at meteorological stations across the world's land areas. Station anomalies (from 1961 to 1990 means) were interpolated into 0.5 degrees latitude/longitude grid cells covering the global land surface (excluding Antarctica), and combined with an existing climatology to obtain absolute monthly values. The dataset includes six mostly independent climate variables (mean temperature, diurnal temperature range, precipitation, wet-day frequency, vapour pressure and cloud cover). Maximum and minimum temperatures have been arithmetically derived from these. Secondary variables (frost day frequency and potential evapotranspiration) have been estimated from the six primary variables using well-known formulae. Time series for hemispheric averages and 20 large sub-continental scale regions were calculated (for mean, maximum and minimum temperature and precipitation totals) and compared to a number of similar gridded products. The new dataset compares very favourably, with the major deviations mostly in regions and/or time periods with sparser observational data. CRU TS3.10 includes diagnostics associated with each interpolated value that indicates the number of stations used in the interpolation, allowing determination of the reliability of values in an objective way. This gridded product will be publicly available, including the input station series(and).

Keywords: space-time climate; air-temperature; data set; variability; precipitation; database; density; series

来源出版物: International Journal of Climatology, 2014, 34(3): 623–642联系邮箱: Jones, PD; P.jones@uea.ac.uk

被引频次: 85

Increasing drought under global warming in observations and models

Dai, AG

Abstract: Historical records of precipitation, streamflow and drought indices all show increased aridity since 1950 over many land areas(1,2). Analyses of model-simulated soil moisture(3,4), drought indices(1,5,6) and precipitation-minus-evaporation(7) suggest increased risk of drought in the twenty-first century. There are, however, large differences in the observed and model-simulated drying patterns(1,2,6). Reconciling these differences is necessary before the model predictions can be trusted. Previous studies(8-12) show that changes in sea surface temperatures have large influences on land precipitation and the inability of the coupled models to reproduce many observed regional precipitation changes is linked to the lack of the observed, largely natural change patterns in sea surface temperatures in coupled model simulations(13). Here I show that the models reproduce not only the influence of El Nino-Southern Oscillation on drought over land, but also the observed global mean aridity trend from 1923 to 2010. Regional differences in observed and model-simulated aridity changes result mainly from natural variations in tropical sea surface temperatures that are often not captured by the coupled models. The unforced natural variations vary among model runs owing to different initial conditions and thus are irreproducible. I conclude that the observed global aridity changes up to 2010 are consistent with model predictions, which suggest severe and widespread droughts in the next 30-90 years over many land areas resulting from either decreased precipitation and/or increased evaporation.

Keywords: interdecadal climate variability; future drought; north-america; sahel drought; temperature; patterns; rainfall; precipitation; 20th-century; simulations

来源出版物: Nature Climate Change, 2013, 3(1): 52–58联系邮箱: Dai, AG; adai@ucar.edu

被引频次: 79

Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

Dufresne, JL; Foujols, MA; Denvil, S; et al.

Abstract: We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes.

Keywords: general-circulation model; convective boundary-layer; sea-ice model; north-atlantic; ocean model; tropical precipitation; cumulus convection; hydrological cycle; sulfate aerosol; air-temperature

来源出版物: Climate Dynamics, 2013, 40(9-10): 2123–2165联系邮箱: Dufresne, JL; Jean-Louis.Dufresne@lmd.jussieu.fr

被引频次: 77

Robustness and uncertainties in the new CMIP5 climate model projections

Knutti, R; Sedlacek, J

Abstract: Estimates of impacts from anthropogenic climate change rely on projections from climate models. Uncertainties in those have often been a limiting factor, in particular on local scales. A new generation of more complex models running scenarios for the upcomingIntergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) is widely, and perhaps naively, expected to provide more detailed and more certain projections. Here we show that projected global temperature change from the new models is remarkably similar to that from those used in IPCC AR4 after accounting for the different underlying scenarios. The spatial patterns of temperature and precipitation change are also very consistent. Interestingly, the local model spread has not changed much despite substantial model development and a massive increase in computational capacity. Part of this model spread is irreducible owing to internal variability in the climate system, yet there is also uncertainty from model differences that can potentially be eliminated. We argue that defining progress in climate modelling in terms of narrowing uncertainties is too limited. Models improve, representing more processes in greater detail. This implies greater confidence in their projections, but convergence may remain slow. The uncertainties should not stop decisions being made.

Keywords: carbon-cycle models; atmosphere-ocean; simpler model; temperature; sensitivity

来源出版物: Nature Climate Change, 2013, 3(4): 369–373联系邮箱: Knutti, R; reto.knutti@env.ethz.ch

MICROBIOLOGY 微生物学

被引频次: 115

The gut microbiota - masters of host development and physiology

Sommer, F; Backhed, F

Abstract: Establishing and maintaining beneficial interactions between the host and its associated microbiota are key requirements for host health. Although the gut microbiota has previously been studied in the context of inflammatory diseases, it has recently become clear that this microbial community has a beneficial role during normal homeostasis, modulating the host's immune system as well as influencing host development and physiology, including organ development and morphogenesis, and host metabolism. The underlying molecular mechanisms of host microorganism interactions remain largely unknown, but recent studies have begun to identify the key signalling pathways of the cross-species homeostatic regulation between the gut microbiota and its host.

Keywords: T-cell responses; germ-free mice; ror-gamma-t; intestinal microbiota; commensal bacteria; lymphoid-tissues; colorectal-cancer; muc2 mucin; adaptive immunity; obesity

来源出版物: Nature Reviews Microbiology, 2013, 11(4): 227–238联系邮箱: Backhed, F; Fredrik.Backhed@wlab.gu.se

被引频次: 105

Post-Treatment HIV-1 Controllers with a Long-Term Virological Remission after the Interruption of Early Initiated Antiretroviral Therapy ANRS VISCONTI Study

Saez-Cirion, A; Bacchus, C; Hocqueloux, L; et al.

Abstract: Combination antiretroviral therapy (cART) reduces HIV-associated morbidities and mortalities but cannot cure the infection. Given the difficulty of eradicating HIV-1, a functional cure for HIV-infected patients appears to be a more reachable short-term goal. We identified 14 HIV patients (post-treatment controllers [PTCs]) whose viremia remained controlled for several years after the interruption of prolonged cART initiated during the primary infection. Most PTCs lacked the protective HLA B alleles that are overrepresented in spontaneous HIV controllers (HICs); instead, they carried risk-associated HLA alleles that were largely absent among the HICs. Accordingly, the PTCs had poorer CD8+ T cell responses and more severe primary infections than the HICs did. Moreover, the incidence of viral control after the interruption of early antiretroviral therapy was higher among the PTCs than has been reported for spontaneous control. Off therapy, the PTCs were able to maintain and, in some cases, further reduce an extremely low viral reservoir. We found that long-lived HIV-infected CD4+ T cells contributed poorly to the total resting HIV reservoir in the PTCs because of a low rate of infection of naive T cells and a skewed distribution of resting memory CD4+ T cell subsets. Our results show that early and prolonged cART may allow some individuals with a rather unfavorable background to achieve long-term infection control and may have important implications in the search for a functional HIV cure.

Keywords: T-cell responses; primary infection; immune function; plasma viremia; viral load; ex-vivo; in-vivo; virus; nonprogressors; replication

来源出版物: Plos Pathogens, 2013, 9(3): e1003211联系邮箱: Saez-Cirion, A; asier.saez-cirion@pasteur.fr

被引频次: 94

10 x '20 Progress-Development of New Drugs Active Against Gram-Negative Bacilli: An Update From the Infectious Diseases Society of America

Boucher, HW; Talbot, GH; Benjamin, DK; et al.

Abstract: Infections caused by antibiotic-resistant bacteria, especially the "ESKAPE" pathogens, continue to increase in frequency and cause significant morbidity and mortality. New antimicrobial agents are greatly needed to treat infections caused by gram-negative bacilli (GNB) resistant to currently available agents. The Infectious Diseases Society of America (IDSA) continues to propose legislative, regulatory, and funding solutions to this continuing crisis. The current report updates the status of development and approval of systemic antibio-tics in the United States as of early 2013. Only 2 new antibiotics have been approved since IDSA's 2009 pipeline status report, and the number of new antibiotics annually approved for marketing in the United States continues to decline. We identified 7 drugs in clinical development for treatment of infections caused by resistant GNB. None of these agents was included in our 2009 list of antibacterial compounds in phase 2 or later development, but unfortunately none addresses the entire spectrum of clinically relevant GNB resistance. Our survey demonstrates some progress in development of new antibacterial drugs that target infections caused by resistant GNB, but progress remains alarmingly elusive. IDSA stresses our conviction that the antibiotic pipeline problem can be solved by the collaboration of global leaders to develop creative incentives that will stimulate new antibacterial research and development. Our aim is the creation of a sustainable global antibacterial drug research and development enterprise with the power in the short term to develop 10 new, safe, and efficacious systemically administered antibiotics by 2020 as called for in IDSA's "10 x '20 Initiative."

Keywords: in-vitro activity; siderophore monosulfactam bal30072; acquired bacterial pneumonia; health-care epidemiology; pseudomonas-aeruginosa; clinical-trials; antimicrobial stewardship; acinetobacter-baumannii; antibacterial agents; beta-lactamases

来源出版物: Clinical Infectious Diseases, 2013, 56(12): 1685–1694联系邮箱: Guidos, RJ; rguidos@idsociety.org

被引频次: 92

Cyclic di-GMP: the First 25 Years of a Universal Bacterial Second Messenger

Romling, U; Galperin, MY; Gomelsky, M

Abstract: Twenty-five years have passed since the discovery of cyclic dimeric (3'-> 5') GMP (cyclic di-GMP or c-di-GMP). From the relative obscurity of an allosteric activator of a bacterial cellulose synthase, c-di-GMP has emerged as one of the most common and important bacterial second messengers. Cyclic di-GMP has been shown to regulate biofilm formation, motility, virulence, the cell cycle, differentiation, and other processes. Most c-di-GMP-dependent signaling pathways control the ability of bacteria to interact with abiotic surfaces or with other bacterial and eukaryotic cells. Cyclic di-GMP plays key roles in lifestyle changes of many bacteria, including transition from the motile to the sessile state, which aids in the establishment of multicellular biofilm communities, and from the virulent state in acute infections to the less virulent but more resilient state characteristic of chronic infectious diseases. From a practical standpoint, modulating c-di-GMP signaling pathways in bacteria could represent a new way of controlling formation and dispersal of biofilms in medical and industrial settings. Cyclic di-GMP participates in interkingdom signaling. It is recognized by mammalian immune systems as a uniquely bacterial molecule and therefore is considered a promising vaccine adjuvant. The purpose of this review is not to overview the whole body of data in the burgeoning field of c-di-GMP-dependent signaling. Instead, we provide a historic perspective on the development of the field, emphasize common trends, and illustrate them with the best available examples. We also identify unresolved questions and highlight new directions in c-di-GMP research that will give us a deeper understanding of this truly universal bacterial second messenger.

Keywords: enterica serovar typhimurium; 3',5'-cyclic diguanylic acid; pilz domain proteins; hd-gyp domain; regulates biofilm formation; dimeric guanosine-monophosphate; pseudomonas-fluorescens pf0-1; signal-transduction systems; general stress-response; prime transcription initiation

来源出版物: Microbiology and Molecular Biology Reviews, 2013, 77(1): 1–52联系邮箱: Romling, U; ute.romling@ki.se

被引频次: 74

New World Bats Harbor Diverse Influenza A Viruses

Tong, SX; Zhu, XY; Li, Y; et al.

Abstract: Aquatic birds harbor diverse influenza A viruses and are a major viral reservoir in nature. The recent discovery of influenza viruses of a new H17N10 subtype in Central American fruit bats suggests that other New World species may similarly carry divergent influenza viruses. Using consensus degenerate RT-PCR, we identified a novel influenza A virus, designated as H18N11, in a flat-faced fruit bat (Artibeus planirostris) from Peru. Serologic studies with the recombinant H18 protein indicated that several Peruvian bat species were infected by this virus. Phylogenetic analyses demonstrate that, in some gene segments, New World bats harbor more influenza virus genetic diversity than all other mammalian and avian species combined, indicative of a long-standing host-virus association. Structural and functional analyses of the hemagglutinin and neuraminidase indicate that sialic acid is not a ligand for virus attachment nor a substrate for release, suggesting a unique mode of influenza A virus attachment and activation of membrane fusion for entry into host cells. Taken together, these findings indicate that bats constitute a potentially important and likely ancient reservoir for a diverse pool of influenza viruses.

Keywords: hemagglutinin membrane glycoprotein; maximum-likelihood; viral polymerase; pb2 protein; sars-like; segment 3; neuraminidase; binding; host; coronaviruses

来源出版物: Plos Pathogens, 2013, 9(10): e1003657联系邮箱: Tong, SX; sot1@cdc.gov

MICROSCOPY 显微镜

被引频次: 28

Mass spectrometry imaging with high resolution in mass and space

Rompp, A; Spengler, B

Abstract: Mass spectrometry (MS) imaging links molecular information and the spatial distribution of analytes within a sample. In contrast to most histochemical techniques, mass spectrometry imaging can differentiate molecular modifications and does not require labeling of targeted compounds. We have recently introduced the first mass spectrometry imaging method that provides highly specific molecular information (high resolution and accuracy in mass) at cellular dimensions (high resolution in space). This method is based on a matrix-assisted laser desorption/ionization (MALDI) imaging source working at atmospheric pressure which is coupled to an orbital trapping mass spectrometer. Here, we present a number of application examples and demonstrate the benefit of 'mass spectrometry imaging with high resolution in mass and space.' Phospholipids, peptides and drug compounds were imaged in a number of tissue samples at a spatial resolution of 5-10 µm. Proteins were analyzed after on-tissue tryptic digestion at 50-mu m resolution. Additional applications include the analysis of single cells and of human lung carcinoma tissue as well as the first MALDI imaging measurement of tissue at 3 mu m pixel size. MS image analysis for all these experiments showed excellent correlation with histological staining evaluation. The high mass resolution (R=30000) and mass accuracy (typically 1 ppm) proved to be essential for specific image generation and reliable identification of analytes in tissue samples. The ability to combine the required high-quality mass analysis with spatial resolution in the range of single cells is a unique feature of our method. With that, it has the potential to supplement classical histochemical protocols and to provide new insights about molecular processes on the cellular level.

Keywords: high-spatial-resolution; paraffin-embedded tissue; maldi-ms; protein identification; lipid-metabolism; molecular-mass; breast-cancer; mouse-brain; biological samples; tryptic peptides

来源出版物: Histochemistry and Cell Biology, 2013, 139(6): 759–783

联系邮箱: Rompp, A; andreas.roempp@anorg.chemie.uni-giessen.de

被引频次: 20

High-resolution noise substitution to measure overfitting and validate resolution in 3D structure determination by single particle electron cryomicroscopy

Chen, SX; McMullan, G; Faruqi, AR; et al.

Abstract: Three-dimensional (3D) structure determination by single particle electron cryomicroscopy (cryoEM) involves the calculation of an initial 3D model, followed by extensive iterative improvement of the orientation determination of the individual particle images and the resulting 3D map. Because there is much more noise than signal at high resolution in the images, this creates the possibility of noise reinforcement in the 3D map, which can give a false impression of the resolution attained. The balance between signal and noise in the final map at its limiting resolution depends on the image processing procedure and is not easily predicted. There is a growing awareness in the cryoEM community of how to avoid such over-fitting and over-estimation of resolution. Equally, there has been a reluctance to use the two principal methods of avoidance because they give lower resolution estimates, which some people believe are too pessimistic. Here we describe a simple test that is compatible with any image processing protocol. The test allows measurement of the amount of signal and the amount of noise from overfitting that is present in the final 3D map. We have applied the method to two different sets of cryoEM images of the enzyme beta-galactosidase using several image processing packages. Our procedure involves substituting the Fourier components of the initial particle image stack beyond a chosen resolution by either the Fourier components from an adjacent area of background, or by simple randomisation of the phases of the particle structure factors. This substituted noise thus has the same spectral power distribution as the original data. Comparison of the Fourier Shell Correlation (FSC) plots from the 3D map obtained using the experimental data with that from the same data with high-resolution noise (HR-noise) substituted allows an unambiguous measurement of the amount of overfitting and an accompanying resolution assessment. A simple formula can be used to calculate an unbiased FSC from the two curves, even when a substantial amount of overfitting is present. The approach is software independent. The user is therefore completely free to use any established method or novel combination of methods, provided the HR-noise test is carried out in parallel. Applying this procedure to cryoEM images of beta-galactosidase shows how overfitting varies greatly depending on the procedure, but in the best case shows no overfitting and a resolution of similar to 6 angstrom.

Keywords: cryo-em structure; 3-dimensional reconstruction; atomic model; angstrom resolution; crystal-structures; escherichia-coli; microscopy; refinement; images; visualization

来源出版物: Ultramicroscopy, 2013, 135: 24–35联系邮箱: Henderson, R; rh15@mrc-lmb.cam.ac.uk

被引频次: 18

Monochromated STEM with a 30 meV-wide, atom-sized electron probe

Krivanek, OL; Lovejoy, TC; Dellby, N; et al.

Abstract: The origins and the recent accomplishments of aberration correction in scanning transmission electron microscopy (STEM) are reviewed. It is remembered that the successful correction of imaging aberrations of round lenses owes much to the successful correction of spectrum aberrations achieved in electron energy loss spectrometers 2-3 decades earlier. Two noteworthy examples of the types of STEM investigation that aberration correction has made possible are shown: imaging of single-atom impurities in graphene and analyzing atomic bonding of single atoms by electron energy loss spectroscopy (EELS). Looking towards the future, a new all-magnetic monochromator is described. The monochromator uses several of the principles pioneered in round lens aberration correction, and it employs stabilization schemes that make it immune to variations in the high voltage of the microscope and in the monochromator main prism current. Tests of the monochromator carried out at 60 keV have demonstrated energy resolution as good as 12 meV and monochromated probe size of similar to 1.2 angstrom. These results were obtained in separate experiments, but they indicate that the instrument can perform imaging and EELS with an atom-sized probe <30 meV wide in energy, and that an improvement in energy resolution to 10 meV and beyond should be possible in the future.

Keywords: energy-loss spectroscopy; 2nd-order aberrations; dedicated stem; microscopy; resolution; spectrometer; lattice; design; optics

来源出版物: Microscopy, 2013, 62(1): 3–21联系邮箱: Krivanek, OL; krivanek@nion.com

被引频次: 17

Compressed sensing electron tomography

Leary, R; Saghi, Z; Midgley, PA; et al.

Abstract: The recent mathematical concept of compressed sensing (CS) asserts that a small number of well-chosen measurements can suffice to reconstruct signals that are amenable to sparse or compressible representation. In addition to powerful theoretical results, the principles of CS are being exploited increasingly across a range of experiments to yield substantial performance gains relative to conventional approaches. In this work we describe the application of CS to electron tomography (ET) reconstruction and demonstrate the efficacy of CS-ET with several example studies. Artefacts present in conventional ET reconstructions such as streaking, blurring of object boundaries and elongation are markedly reduced, and robust reconstruction is shown to be possible from far fewer projections than are normally used. The CS-ET approach enables more reliable quantitative analysis of the reconstructions as well as novel 3D studies from extremely limited data.

Keywords: total-variation minimization; image-reconstruction; materials science; inverse problems; basis pursuit; microscopy; nanoparticles; decomposition; resolution; reduction

来源出版物: Ultramicroscopy, 2013, 131: 70–91联系邮箱: Leary, R; rkl26@cam.ac.uk

被引频次: 17

Control of radiation damage in the TEM

Egerton, RF

Abstract: The problem of electron-beam damage in the transmission electron microscope is reviewed, with an emphasis on radiolysis processes in soft materials and organic specimens. Factors that determine the dose-limited resolution are identified for three different operational modes: bright-field scattering-contrast, phase-contrast and dark-field microscopy. Methods of reducing radiation damage are discussed, including low-dose techniques, cooling or encapsulating the specimen, and the choice of imaging mode, incident-beam diameter and incident-electron energy. Further experiments are suggested as a means of obtaining a better understanding and control of electron-beam damage.

Keywords: transmission electron-microscopy; energy-loss spectroscopy; beam-induced damage; phase-plate; copper-phthalocyanine; sensitive specimens; irradiation damage; room-temperature; crystals; polymers

来源出版物: Ultramicroscopy, 2013, 127: 100–108联系邮箱: Egerton, RF; regerton@ualberta.ca

MINERALOGY 矿物学

被引频次: 27

Major types and time-space distribution of Mesozoic ore deposits in South China and their geodynamic settings

Mao, JW; Cheng, YB; Chen, MH; et al.

Abstract: The ore deposits of the Mesozoic age in South China can be divided into three groups, each with different metal associations and spatial distributions and each related to major magmatic events. The first event occurred in the Late Triassic (230-210 Ma), the second in the Mid-Late Jurassic (170-150 Ma), and the third in the Early-Mid Cretaceous (120-80 Ma). The Late Triassic magmatic event and asso-ciated mineralization is characterized by peraluminous granite-related W-Sn-Nb-Ta mineral deposits. The Triassic ore deposits are considerably disturbed or overprinted by the later Jurassic and Cretaceous tectono-thermal episodes. The Mid-Late Jurassic magmatic and mineralization events consist of 170-160 Ma porphyry-skarn Cu and Pb-Zn-Ag vein deposits associated with I-type granites and 160-150 Ma metaluminous granite-related polymetallic W-Sn deposits. The Late Jurassic metaluminous granite-related W-Sn deposits occur in a NE-trending cluster in the interior of South China, such as in the Nanling area. In the Early-Mid Cretaceous, from about 120 to 80 Ma, but peaking at 100-90 Ma, subvolcanic-related Fe deposits developed and I-type calc-alkaline granitic intrusions formed porphyry Cu-Mo and porphyry-epithermal Cu-Au-Ag mineral systems, whereas S-type peraluminous and/or metaluminous granitic intrusions formed polymetallic Sn deposits. These Cretaceous mineral deposits cluster in distinct areas and are controlled by pull-apart basins along the South China continental margin. Based on mineral assemblage, age, and space-time distribution of these mineral systems, integrated with regional geological data and field observations, we suggest that the three magmatic-mineralization episodes are the result of distinct geodynamic regimes. The Triassic peraluminous granites and associated W-Sn-Nb-Ta mineralization formed during post-collisional processes involving the South China Block, the North China Craton, and the Indo-China Block, mostly along the Dabie-Sulu and Songma sutures. Jurassic events were initially related to the shallow oblique subduction of the Izanagi plate beneath the Eurasian continent at about 175 Ma, but I-type granitoids with porphyry Cu and vein-type Pb-Zn-Ag deposits only began to form as a result of the breakup of the subducted plate at 170-160 Ma, along the NNE-trending Qinzhou-Hangzhou belt (also referred to as Qin-Hang or Shi-Hang belt), which is the Neoproterozoic suture that amalgamates the Yangtze Craton and Cathaysia Block. A large subduction slab window is assumed to have formed in the Nanling and adjacent areas in the interior of South China, triggering the uprise of asthenospheric mantle into the upper crust and leading to the emplacement of metaluminous granitic magma and associated polymetallic W-Sn mineralization. A relatively tectonically quiet period followed between 150 and 135 Ma in South China. From 135 Ma onward, the angle of convergence of the Izanagi plate changed from oblique to parallel to the coastline, resulting in continental extensional tectonics and reactivation of regional-scale NE-trending faults, such as the Tan-Lu fault. This widespread extension also promoted the development of NE-trending pull-apart basins and metamorphic core complexes, accompanied by volcanism and the formation of epithermal Cu-Au deposits, granite-related polymetallic Sn-(W) deposits and hydrothermal U deposits between 120 and 80 Ma (with a peak activity at 100-90 Ma).

Keywords: u-pb zircon; molybdenite re-os; cu-au-mo; xiangshan uranium deposit; hf isotopic constraints; yangtze-river valley; dabie orogenic belt; sr-nd isotope; lu fault zone; jiangxi province

来源出版物: Mineralium Deposita, 2013, 48(3): 267–294联系邮箱: Mao, JW; jingwenmao@263.net

被引频次: 20

Element recycling from subducting slabs to arc crust: A review

Spandler, C; Pirard, C

Abstract: Subduction zones not only return oceanic lithosphere into the mantle, but are also sites where chemical components are transferred from the downgoing plate back to the surface in arc crust and, to a lesser extent, fore-arc and back-arc basins. Understanding of subduction-zone processes has evolved significantly over a relatively brief 40-year research history, thanks to combined insights from experimental petrology, geophysics, numerical and thermodynamic modelling, arc magma geochemistry and studies of high- and ultrahigh-pressure metamorphic rocks. Early models considered aqueous fluids produced by metamorphic devolatilisation of the slab to be responsible for directly transferring chemical components of the slab into the overlying mantle wedge, as well as fluxing melting of the mantle wedge to produce arc basalt. Subducting crustal rocks were considered too cold to melt under most circumstances. However, the latest generation of thermal modelling combined with improved understanding of the chemistry and phase petrology of subduction-zone fluids and melts indicates that conditions for deep slab melting are likely met in subduction zones, provided that free fluid is available at sub-arc depths.

We outline a model to explain element transfer out of subducting slabs that involves serpentinite subduction and slab partial melting. Serpentinite is likely to comprise part of the subducting slab, either as downgoing oceanic lithosphere that was hydrated at, or near, the seafloor, or as down-dragged fore-arc mantle wedge that was initially hydrated at shallow levels by aqueous fluids emanating from underthrust crustal rocks. Slab coupling with convecting asthenospheric mantle at sub-arc depths leads to slab heating and devolatilisation of deep slab serpentinite and/or hydrated melange atop of the slab. Interaction between these fluids and coesite-phengite eclogite at the top of the slab produces hydrous slab melts, which then migrate out of the slab to ultimately contribute to arc magma generation. In this scenario hydrous slab melts dominate element transfer from the slab to arc magmas, although serpentinites (and/or related hybrid melange rocks) are the initial source of H2O and some trace elements (e.g., B, Cl, As, and Sb). This model conforms to petrological and geophysical constraints on deep subduction conditions, and in general is consistent with the geology of blueschist-and eclogite-facies terranes and key geochemical and isotopic features of arc lavas.

Keywords: middle america trench; trace-element; island-arc; high-pressure; fluid-flow; mantle wedge; fore-arc; continental-crust; chemical-composition; melting relations

来源出版物: Lithos, 2013, 170: 208–223联系邮箱: Spandler, C; Carl.Spandler@jcu.edu.au

被引频次: 20

Timescales of crustal melting in the Higher Himalayan Crystallines (Sikkim, Eastern Himalaya) inferred from trace element-constrained monazite and zircon chronology

Rubatto, D; Chakraborty, S; Dasgupta, S

Abstract: The petrology and timing of crustal melting has been investigated in the migmatites of the Higher Himalayan Crystalline (HHC) exposed in Sikkim, India. The metapelites underwent pervasive partial melting through hydrous as well as dehydration melting reactions involving muscovite and biotite to produce a main assemblage of quartz, K-feldspar, plagioclase, biotite, garnet +/- A sillimanite. Peak metamorphic conditions were 8-9 kbar and 800 A degrees C. Monazite and zircon crystals in several migmatites collected along a N-S transect show multiple growth domains. The domains were analyzed by microbeam techniques for age (SHRIMP) and trace element composition (LA-ICP-MS) to relate ages to conditions of formation. Monazite preserves the best record of metamorphism with domains that have different zoning pattern, composition and age. Zircon was generally less reactive than monazite, with metamorphic growth zones preserved in only a few samples. The growth of accessory minerals in the presence of melt was episodic in the interval between 31 and 17 Ma, but widespread and diachronous across samples. Systematic variations in the chemical composition of the dated mineral zones (HREE content and negative Eu anomaly) are related to the variation in garnet and K-feldspar abundances, respectively, and thus to metamorphic reactions and P-T stages. In turn, this allows prograde versus decompressional and retrograde melt production to be timed. A hierarchy of timescales characterizes melting which occurred over a period of 15 Ma (31-17 Ma): a given block within this region traversed the field of melting in 5-7 Ma, whereas individual melting reactions lasted for time durations below, or approaching, the resolution of microbeam dating techniques (0.6 Ma). An older 36 Ma high-grade event is recorded in an allocthonous relict related to mafic lenses. We identify two sections of the HHC in Sikkim that traversed similar P-T conditions at different times, separated by a tectonic discontinuity. The higher structural levels reached melting and peak conditions later (26-23 Ma) than the lower structural levels (31-27 Ma). Diachronicity across the HHC cannot be reconciled with channel flow models in their simplest form, as it requires two similar high-grade sections to move independently during collision.

Keywords: u-pb geochronology; ablation-icp-ms; central australia; metamorphic core; phase-relations; everest region; prograde metamorphism; numerical-models; tibetan orogen; channel flows

来源出版物: Contributions To Mineralogy and Petrology, 2013, 165(2): 349–372联系邮箱: Rubatto, D; Daniela.rubatto@anu.edu.au

被引频次: 19

Spatio-temporal distribution and tectonic settings of the major iron deposits in China: An overview

Zhang, ZC; Hou, T; Santosh, M; et al.

Abstract: China has a rich reserve of iron ores and hosts most of the major types of iron deposits recognized worldwide. However, among these, the banded iron formation (BIF), skarn, apatite-magnetite, volcanic-hosted, sedimentary hematite and magmatic Ti-Fe-(V) deposits constitute the most economically important types. High-grade iron ores (>50% Fe) are relatively rare, and are mostly represented by the skarn-type. Most of the BIF deposits formed in the Neoarchean, with a peak at similar to 2.5 Ga, and are mainly distributed in the North China Craton. The majority of these is associated with volcanic rocks, and therefore belongs to the Algoma-type. The superior-type BIF deposits formed during the Paleoproterozoic occur subordinately (ca. 25%), and are related mainly to rifts (or passive continental margins). In addition, minor Superior-type BIF deposits have also been recognized. The skarn iron deposits are widely distributed in China, especially in the uplifted areas of eastern China, and form several large iron ore clusters. These ore deposits are genetically associated with intermediate, intermediate-felsic and felsic intrusions with a peak age of formation at ca. 130 Ma. They display common characteristics including alteration and nature of mineralization. The apatite-magnetite deposits occurring in the Ningwu and Luzong Cretaceous terrigenous volcanic basins along the Middle-Lower Yangtze River Valley, are spatially and temporally associated with dioritic subvolcanic intrusions. The ores in this type are characterized by magnetite and apatite. The volcanic-hosted iron deposits are associated with submarine volcanic-sedimentary sequences, and are widely distributed in the orogenic belts of western China, including Western Tianshan, Eastern Tianshan, Beishan, Altay, Kaladawan area in the eastern part of the Altyn Tagh Mountain and southwestern margin of South China Block. These deposits show a considerable age range, from Proterozoic to Mesozoic, but with more than 70% were formed in the Paleozoic, especially during the Late Paleozoic. The metallogenesis in these deposits can be correlated to the space-time evolution of the submarine volcanism, and their relationship to volcanic lithofacies variation, such as central, proximal and distal environments of ore formation. The sedimentary hematite deposits are widespread in China, among which the "Xuanlong-type" in the North China Craton and the "Ningxiang-type" in the South China Block are the most economically important. All these deposits formed during transgressions in a shallow-marine environment. Magmatic Ti-Fe-(V) deposits are dominantly distributed in the Panxi area in Sichuan province and Chengde area in Hebei province. They are dominated low-grade disseminated ores, and unlike the other types of iron deposits, associated sulfide deposits are absent, with magnetite, titanomagnetite and ilmenite as the dominant ore minerals. In the Panxi area in the central Emeishan large igneous province along the western margin of South China Block, the ores are hosted in the ca. 260 Ma mafic layered intrusions, whereas the ores in the Chengde areaare associated with the Mesoproterozoic anorthosite complex. The distinct spatio-temporal characteristics of the various iron deposits in China correlate with the multiple tectonomagmatic events associated with the prolonged geological history of the region involving accretion, assembly and rifting.

Keywords: large igneous province; yangtze-river valley; xinjie layered intrusion; hf isotopic constraints; eastern hebei province; asian orogenic belt; south china; sw china; ore-deposits; formation age

来源出版物: Ore Geology Reviews, 2014, 57: 247–263联系邮箱: Zhang, ZC; zczhang@cugb.edu.cn

被引频次: 19

Metallogeny during continental outgrowth in the Columbia supercontinent: Isotopic characterization of the Zhaiwa Mo-Cu system in the North China Craton

Deng, XH; Chen, YJ; Santosh, M; et al.

Abstract: The Eastern Qinling Molybdenum Belt (EQMB) in central China represents the largest Mo province in the world. Located at the southern margin of the North China Craton, this Mo province is largely associated with Mesozoic granitoids. Here we report Re-Os isochron age of 1761±33 Ma (2 sigma, MSWD=2.9) from molybdenite in the recently discovered Zhaiwa porphyry Mo-Cu system within the EQMB. This age coincides with the peak eruption period (1.78-1.75 Ga) of the Xiong'er Group volcanic rocks which unconformably overlie the Taihua Supergroup and are interpreted to have developed on a continental arc The Re concentrations (1 to 43 ppm) of the Zhaiwa molybdenites are similar to those of typical porphyry Cu-Mo-Au systems developed on continental arcs. The delta S-34 values of the Zhaiwa ores (2.7-7.3 parts per thousand, average 52 parts per thousand) suggest that the sulfur was mainly sourced from a magmatic system. The sulfides from the ores yield Sri average of 0.70533, similar to that of the Xiong'er Group (0.70547), albeit higher than that of the Kuanping Group (0.70334) and lower than the Taihua Supergroup (0.70763), suggesting a mixed source. The average epsilon(Nd)(1.76 Ga) of the sulfides from the ores (0.9) falls between the averages of the Taihua Supergroup (ca. -6.8) and the Kuanping Group (ca. 7.4). The Pb isotope ratios of the ores are similar to, but slightly higher than those of the Taihua Supergroup, reflecting preferential leaching of radiogenic Pb from the Taihua Supergroup by magmatic fluids. Integrated data and interpretations constrain the Zhaiwa Mo-Cu deposit to be a porphyry mineral system developed within a ca. 1.76 Ga continental arc related to oceanic plate subduction beneath the southern margin of the North China Craton. A correlation between tectonic settings and metallogenic types clearly indicate that the Xiong'er Group was formed in a volcanic arc, confirming Paleo-Mesoproterozoic continental outgrowth along the margins of the Columbia supercontinent. The isotopic characterization of the Zhaiwa deposit provides new insights into the enigma of the widespread distribution of large and super-large Mo deposits of EQMB along the southern margin of the North China Craton.

Keywords: Re-Os ages; sm-nd; U-Pb; gold deposits; mesoproterozoic supercontinent; molybdenum deposits; southern margin; orogenic belt; sr isotope; Rb-Sr

来源出版物: Ore Geology Reviews, 2013, 51: 43–56联系邮箱: Chen, YJ; gigyjchen@126.com

MINING MINERAL PROCESSING 矿业与矿物加工

被引频次: 37

Recent progress in research on tungsten materials for nuclear fusion applications in Europe

Rieth, M; Dudarev, SL; de Vicente, SMG; et al.

Abstract: The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme's main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments.

Keywords: space gaussian pseudopotentials; plasma-sprayed tungsten; to-ductile transition; w-based alloys; fracture-behavior; power-plant; polycrystalline tungsten; facing material; evolution; deuterium

来源出版物: Journal of Nuclear Materials, 2013, 432(1-3): 482–500联系邮箱: Rieth, M; Michael.rieth@kit.edu

被引频次: 23

Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

Matthews, GF

Abstract: Installation of the ITER-like Wall (ILW) in JET, has allowed a direct comparison of operation with all carbon plasma facing components (PFCs) to an all metal beryllium/tungsten first-wall under otherwise nearly identical conditions. The JET results are comparedwith experience from ASDEX-Upgrade where there was a gradual change to a full tungsten first-wall over an extended period. The scope of this review ranges from experience with machine conditioning, impurities and breakdown to material migration, fuel retention, disruptions, impact on operational space, energy confinement and compatibility with impurity seeding. Significant changes are reported, not only in the physics directly related to plasma-surface interactions but also to the main plasma which is strongly affected in unexpected ways, impacting many aspects of tokamak operation.

Keywords: asdex upgrade; divertor; migration; tungsten

来源出版物: Journal of Nuclear Materials, 2013, 438: S2–S10联系邮箱: Matthews, GF; gfm@jet.uk

被引频次: 21

A full tungsten divertor for ITER: Physics issues and design status

Pitts, RA; Carpentier, S; Escourbiac, F; et al.

Abstract: Budget restrictions have forced the ITER Organization to reconsider the baseline divertor strategy, in which operations would begin with carbon (C) in the high heat flux regions, changing out to a full-tungsten (W) variant before the first nuclear campaigns. Substantial cost reductions can be achieved if one of these two divertors is eliminated. The new strategy implies not only that ITER would start-up on a full-W divertor, but that this component should survive until well into the nuclear phase. This paper considers the risks engendered by such an approach with regard to known W plasma-material interaction issues and briefly presents the current status of a possible full-W divertor design.

Keywords: disruption simulation experiments; transient events; plasma; erosion; beryllium; tokamaks; targets; devices; armor

来源出版物: Journal of Nuclear Materials, 2013, 438: S48–S56联系邮箱: Pitts, RA; richard.pitts@iter.org

被引频次: 19

Spatio-temporal distribution and tectonic settings of the major iron deposits in China: An overview

Zhang, ZC; Hou, T; Santosh, M; et al.

Abstract: China has a rich reserve of iron ores and hosts most of the major types of iron deposits recognized worldwide. However, among these, the banded iron formation (BIF), skarn, apatite-magnetite, volcanic-hosted, sedimentary hematite and magmatic Ti-Fe-(V) deposits constitute the most economically important types. High-grade iron ores (>50% Fe) are relatively rare, and are mostly represented by the skarn-type. Most of the BIF deposits formed in the Neoarchean, with a peak at similar to 2.5 Ga, and are mainly distributed in the North China Craton. The majority of these is associated with volcanic rocks, and therefore belongs to the Algoma-type. The superior-type BIF deposits formed during the Paleoproterozoic occur subordinately (ca. 25%), and are related mainly to rifts (or passive continental margins). In addition, minor Superior-type BIF deposits have also been recognized. The skarn iron deposits are widely distributed in China, especially in the uplifted areas of eastern China, and form several large iron ore clusters. These ore deposits are genetically associated with intermediate, intermediate-felsic and felsic intrusions with a peak age of formation at ca. 130 Ma. They display common characteristics including alteration and nature of mineralization. The apatite-magnetite deposits occurring in the Ningwu and Luzong Cretaceous terrigenous volcanic basins along the Middle-Lower Yangtze River Valley, are spatially and temporally associated with dioritic subvolcanic intrusions. The ores in this type are characterized by magnetite and apatite. The volcanic-hosted iron deposits are associated with submarine volcanic-sedimentary sequences, and are widely distributed in the orogenic belts of western China, including Western Tianshan, Eastern Tianshan, Beishan, Altay, Kaladawan area in the eastern part of the Altyn Tagh Mountain and southwestern margin of South China Block. These deposits show a considerable age range, from Proterozoic to Mesozoic, but with more than 70% were formed in the Paleozoic, especially during the Late Paleozoic. The metallogenesis in these deposits can be correlated to the space-time evolution of the submarine volcanism, and their relationship to volcanic lithofacies variation, such as central, proximal and distal environments of ore formation. The sedimentary hematite deposits are widespread in China, among which the "Xuanlong-type" in the North China Craton and the "Ningxiang-type" in the South China Block are the most economically important. All these deposits formed during transgressions in a shallow-marine environment. Magmatic Ti-Fe-(V) deposits are dominantly distributed in the Panxi area in Sichuan province and Chengde area in Hebei province. They are dominated low-grade disseminated ores, and unlike the other types of iron deposits, associated sulfide deposits are absent, with magnetite, titanomagnetite and ilmenite as the dominant ore minerals. In the Panxi area in the central Emeishan large igneous province along the western margin of South China Block, the ores are hosted in the ca. 260 Ma mafic layered intrusions, whereas the ores in the Chengde area are associated with the Mesoproterozoic anorthosite complex. The distinct spatio-temporal characteristics of the various iron deposits in China correlate with the multiple tectonomagmatic events associated with the prolonged geological history of the region involving accretion, assembly and rifting.

来源出版物: Ore Geology Reviews, 2014, 57: 247–263联系邮箱: Zhang, ZC; zczhang@cugb.edu.cn

被引频次: 19

Metallogeny during continental outgrowth in the Columbia supercontinent: Isotopic characterization of the Zhaiwa Mo-Cu system in the North China Craton

Deng, XH; Chen, YJ; Santosh, M; et al.

Keywords: Re-Os ages; sm-nd; U-Pb; gold deposits; mesoproterozoic supercontinent; molybdenum deposits; southern margin; orogenic belt; Sr isotope; Rb-Sr

来源出版物: Ore Geology Reviews, 2013, 51: 43–56联系邮箱: Chen, YJ; gigyjchen@126.com

MULTIDISCIPLINARY SCIENCES 综合科学

被引频次: 642

Multiplex Genome Engineering Using CRISPR/Cas Systems

Cong, L; Ran, FA; Cox, D; et al.

Abstract: Functional elucidation of causal genetic variants and elements requires precise genome editing technologies. The type II prokaryotic CRISPR (clustered regularly interspaced short palindromic repeats)/Cas adaptive immune system has been shown to facilitate RNA-guided site-specific DNA cleavage. We engineered two different type II CRISPR/Cas systems and demonstrate that Cas9 nucleases can be directed by short RNAs to induce precise cleavage at endogenous genomic loci in human and mouse cells. Cas9 can also be converted into a nicking enzyme to facilitate homology-directed repair with minimal mutagenic activity. Lastly, multiple guide sequences can be encoded into a single CRISPR array to enable simultaneous editing of several sites within the mammalian genome, demonstrating easy programmability and wide applicability of the RNA-guided nuclease technology.

Keywords: streptococcus-thermophilus; immune-system; tal effectors; cas systems; small rnas; dna; bacteria; endonuclease; nucleases; defense

来源出版物: Science, 2013, 339(6121): 819–823联系邮箱: Zhang, F; zhang@broadinstitute.org

被引频次: 622

RNA-Guided Human Genome Engineering via Cas9

Mali, P; Yang, LH; Esvelt, KM; et al.

Abstract: Bacteria and archaea have evolved adaptive immune defenses, termed clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems, that use short RNA to direct degradation of foreign nucleic acids. Here, we engineer the type II bacterial CRISPR system to function with custom guide RNA (gRNA) in human cells. For the endogenous AAVS1 locus, we obtained targeting rates of 10 to 25% in 293T cells, 13 to 8% in K562 cells, and 2 to 4% in induced pluripotent stem cells. We show that this process relies on CRISPR components; is sequence-specific; and, upon simultaneous introduction of multiple gRNAs, can effect multiplex editing of target loci. We also compute a genome-wide resource of similar to 190 K unique gRNAs targeting similar to 40.5% of human exons. Our results establish an RNA-guided editing tool for facile, robust, and multiplexable human genome engineering.

Keywords: zinc-finger nucleases; synthetic biology; mammalian-cells; gene correction; in-vivo; systems; cleavage; bacteria; immunity; specificities

来源出版物: Science, 2013, 339(6121): 823–826联系邮箱: Church, GM; gchurch@genetics.med.harvard.edu

被引频次: 619

A polymer tandem solar cell with 10.6% power conversion efficiency

You, JB; Dou, LT; Yoshimura, K; et al.

Abstract: An effective way to improve polymer solar cell efficiency is to use a tandem structure, as a broader part of the spectrum of solar radiation is used and the thermalization loss of photon energy is minimized. In the past, the lack of high-performance low-bandgap polymers was the major limiting factor for achieving high-performance tandem solar cell. Here we report the development of a high

performance low bandgap polymer (bandgap <1.4 eV), poly[2,7-(5,5-bis-(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2',3'-d]pyran)-alt-4,7-(5,6-difluoro-2,1,3-benzothia diazole)] with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions (25 degrees C, 1000 Wm-2, IEC 60904-3 global), which is the first certified polymer solar cell efficiency over 10%.

Keywords: field-effect transistors; open-circuit voltage; low-bandgap polymer; photovoltaic cells; high-performance; organic photovoltaics; oxide nanoparticles; conjugated polymers; transport; acceptor

来源出版物: Nature Communications, 2013, 4: 1446联系邮箱: Li, G; gangl@ucla.edu

被引频次: 590

Sequential deposition as a route to high-performance perovskite-sensitized solar cells

Burschka, J; Pellet, N; Moon, SJ; et al.

Abstract: Following pioneering work(1), solution-processable organic-inorganic hybrid perovskites-such as CH3NH3PbX3(X=Cl, Br, I)-have attracted attention as light-harvesting materials for mesoscopic solar cells(2-15). So far, the perovskite pigment has been deposited in a single step onto mesoporous metal oxide films using a mixture of PbX2and CH3NH3X in a common solvent. However, the uncontrolled precipitation of the perovskite produces large morphological variations, resulting in a wide spread of photovoltaic performance in the resulting devices, which hampers the prospects for practical applications. Here we describe a sequential deposition method for the formation of the perovskite pigment within the porous metal oxide film. PbI2is first introduced from solution into a nanoporous titanium dioxide film and subsequently transformed into the perovskite by exposing it to a solution of CH3NH3I. We find that the conversion occurs within the nanoporous host as soon as the two components come into contact, permitting much better control over the perovskite morphology than is possible with the previously employed route. Using this technique for the fabrication of solid-state mesoscopic solar cells greatly increases the reproducibility of their performance and allows us to achieve a power conversion efficiency of approximately 15 per cent (measured under standard AM1.5G test conditions on solar zenith angle, solar light intensity and cell temperature). This two-step method should provide new opportunities for the fabrication of solution-processed photovoltaic cells with unprecedented power conversion efficiencies and high stability equal to or even greater than those of today's best thin-film photovoltaic devices.

Keywords: organometal halide perovskites; efficient; intercalation; nanocrystals; exchange; raman

来源出版物: Nature, 2013, 499(7458): 316联系邮箱: Gratzel, M; michael.graetzel@epfl.ch

被引频次: 411

Cancer Genome Landscapes

Vogelstein, B; Papadopoulos, N; Velculescu, VE; et al.

Abstract: Over the past decade, comprehensive sequencing efforts have revealed the genomic landscapes of common forms of human cancer. For most cancer types, this landscape consists of a small number of "mountains" (genes altered in a high percentage of tumors) and a much larger number of "hills" (genes altered infrequently). To date, these studies have revealed similar to 140 genes that, when altered by intragenic mutations, can promote or "drive" tumorigenesis. A typical tumor contains two to eight of these "driver gene" mutations; the remaining mutations are passengers that confer no selective growth advantage. Driver genes can be classified into 12 signaling pathways that regulate three core cellular processes: cell fate, cell survival, and genome maintenance. A better understanding of these pathways is one of the most pressing needs in basic cancer research. Even now, however, our knowledge of cancer genomes is sufficient to guide the development of more effective approaches for reducing cancer morbidity and mortality.

Keywords: cell lung-cancer; protein-protein interactions; tert promoter mutations; histone-modifying genes; acute myeloid-leukemia; 21 breast cancers; colorectal-cancer; somatic mutations; pancreatic-cancer; tumor-suppressor

来源出版物: Science, 2013, 339(6127): 1546–1558联系邮箱: Kinzler, KW; kinzlke@jhmi.edu

MYCOLOGY 真菌学

被引频次: 50

Families of Dothideomycetes

Hyde, KD; Jones, EBG; Liu, JK; et al.

Abstract: Dothideomycetes comprise a highly diverse range of fungi characterized mainly by asci with two wall layers (bitunicate asci) and often with fissitunicate dehiscence. Many species are saprobes, with many asexual states comprising important plant pathogens. They are also endophytes, epiphytes, fungicolous, lichenized, or lichenicolous fungi. They occur in terrestrial, freshwater and marine habitats in almost every part of the world. We accept 105 families in Dothideomycetes with the new families Anteagloniaceae, Bambusicolaceae, Biatriosporaceae, Lichenoconiaceae, Muyocopronaceae, Paranectriellaceae, Roussoellaceae, Salsugineaceae, Seynesiopeltidaceae and Thyridariaceae introduced in this paper. Each family is provided with a description and notes, including asexual and asexual states, and if more than one genus is included, the type genus is also characterized. Each family is provided with at least one figure-plate, usually illustrating the type genus, a list of accepted genera, including asexual genera, and a key to these genera. A phylogenetic tree based on four gene combined analysis add support for 64 of the families and 22 orders, including the novel orders, Dyfrolomycetales, Lichenoconiales, Lichenotheliales, Monoblastiales, Natipusillales, Phaeotrichales and Strigulales. The paper is expected to provide a working document on Dothideomycetes which can be modified as new data comes to light. It is hoped that by illustrating types we provide stimulation and interest so that more work is carried out in this remarkable group of fungi.

Keywords: ribosomal dna-sequences; morphologically similar genera; foliicolous lichenized fungi; intertidal mangrove wood; leaf-inhabiting fungi; fresh-water habitats; new-zealand fungi; russian far-east; papua-new-guinea; sp-nov

来源出版物: Fungal Diversity, 2013, 63(1): 1–313联系邮箱: Hyde, KD; kdhyde3@gmail.com

被引频次: 30

An evidence-based consensus for the classification of arbuscular mycorrhizal fungi (Glomeromycota)

Redecker, D; Schussler, A; Stockinger, H; et al.

Abstract: The publication of a large number of taxon names at all levels within the arbuscular mycorrhizal fungi (Glomeromycota) has resulted in conflicting systematic schemes and generated considerable confusion among biologists working with these important plant symbionts. A group of biologists with more than a century of collective experience in the systematics of Glomeromycota examined all available molecular-phylogenetic evidence within the framework of phylogenetic hypotheses, incorporating morphological characters when they were congruent. This study is the outcome, wherein the classification of Glomeromycota is revised by rejecting some new names on the grounds that they are founded in error and by synonymizing others that, while validly published, are not evidence-based. The proposed "consensus" will provide a framework for additional original research aimed at clarifying the evolutionary history of this important group of symbiotic fungi.

Keywords: genera; scutellospora; revision; nov.; archaeosporaceae; endogonaceae; communities; phylogeny; families; glomales

来源出版物: Mycorrhiza, 2013, 23(7): 515–531联系邮箱: Redecker, D; dirk.redecker@dijon.inra.fr

被引频次: 28

New species and phylogeny of Perenniporia based on morphological and molecular characters

Zhao, CL; Cui, BK; Dai, YC

Abstract: Three new resupinate, poroid, wood-inhabiting fungi, Perenniporia aridula, P. bannaensis and P. substraminea, are introduced on the basis of morphological and molecular characters. Molecular study based on sequence data from the ribosomal ITS and LSU regions supported the three new species' positions in Perenniporia s.s., and all of them formed monophyletic lineages with strong support (100 % BP, 1.00 BPP). Phylogenetic analysis revealed seven clades for the 31 species of Perenniporia s.l. used in this study. Among them, Perenniporiella clustered with Perenniporia ochroleuca group, and then subsequently grouped with Abundisporus. In addition, the P. ochroleuca group, the P. vicina group, the P. martia group and P. subacida formed well supported monophyletic entities, which could be recognized as distinct genera, and they are not related to P. medulla-panis which belongs to Perenniporia s.s. clade. An identification key to 38 species of Perenniporia occurring in China is provided.

Keywords: sp-nov; neotropical polypores; china; basidiomycota; fungi; taxa; aphyllophorales; forest

来源出版物: Fungal Diversity, 2013, 58(1): 47–60联系邮箱: Cui, BK; baokaicui@yahoo.com.cn

被引频次: 25

Phylogenetic evaluation of Geomyces and allies reveals no close relatives of Pseudogymnoascus destructans, comb. nov., in bat hibernacula of eastern North America

Minnis, AM; Lindner, DL

Abstract: White-nose syndrome (WNS) of bats, caused by the fungus previously known as Geomyces destructans, has decimated populations of insectivorous bats in eastern North America. Recent work on fungi associated with bat hibernacula uncovered a large number of species of Geomyces and allies, far exceeding the number of described species. Communication about these species has been hindered by the lack of a modem taxonomic evaluation, and a phylogenetic framework of the group is needed to understand the origin of G. destructans and to target closely related species and their genomes for the purposes of understanding mechanisms of pathogenicity. We addressed these issues by generating DNA sequence data for the internal transcribed spacer (ITS) region, nuclear large subunit (LSU) rDNA, MCM7, RPB2, and TEF1 from a diverse array of Geomyces and allies that included isolates recovered from bat hibernacula as well as those that represent important type species. Phylogenetic analyses indicate Geomyces and allies should be classified in the family Pseudeurotiaceae, and the genera Geomyces, Gymnostellatospora, and Pseudogymnoascus should be recognized as distinct. True Geomyces are restricted to a basal lineage based on phylogenetic placement of the type species, Geomyces auratus. Thus, G. destructans is placed in genus Pseudogymnoascus. The closest relatives of Pseudogymnoascus destructans are members of the Pseudogymnoascus roseus species complex, however, the isolated and long branch of P. destructans indicates that none of the species included in this study are closely related, thus providing further support to the hypothesis that this pathogen is non-native and invasive in eastern North America. Several conidia-producing isolates from bat hibernacula previously identified as members of Pseudeurotium are determined to belong to the genus Leuconeurospora, which is widespread, especially in colder regions. Teberdinia hygrophila is transferred to Pseudeurotium as Pseudeurotium hygrophilum, comb. nov., in accordance with the one name per fungus system of classification, and two additional combinations are made in Pseudogymnoascus including Pseudogymnoascus carnis and Pseudogymnoascus pannorum. Additional sampling from other regions of the world is needed to better understand the evolution and biogeography of this important and diverse group of fungi. Published by Elsevier Ltd on behalf of The British Mycological Society.

Keywords: fungal pathogen; united-states; ribosomal dna; mixed models; sequences; evolution; nuclear; genus; gymnostellatospora; pseudeurotiaceae

来源出版物: Fungal Biology, 2013, 117(9): 638–649联系邮箱: Lindner, DL; dlindner@fs.fed.us

被引频次: 22

Diaporthe: a genus of endophytic, saprobic and plant pathogenic fungi

Gomes, RR; Glienke, C; Videira, SIR; et al.

Abstract: Diaporthe (Phomopsis) species have often been reported as plant pathogens, non-pathogenic endophytes or saprobes, commonly isolated from a wide range of hosts. The primary aim of the present study was to resolve the taxonomy and phylogeny of a large collection of Diaporthe species occurring on diverse hosts, either as pathogens, saprobes, or as harmless endophytes. In the present study we investigated 243 isolates using multi-locus DNA sequence data. Analyses of the rDNA internal transcribed spacer (ITS1, 5.8S, ITS2) region, and partial translation elongation factor 1-alpha (TEF1), beta-tubulin (TUB), histone H3 (HIS) and calmodulin (CAL) genes resolved 95 clades. Fifteen new species are described, namely Diaporthe arengae, D. brasiliensis, D. endophytica, D. hongkongensis, D. inconspicua, D. infecunda, D. mayteni, D. neoarctii, D. oxe, D. paranensis, D. pseudomangiferae, D. pseudophoenicicola, D. raonikayaporum, D. schini and D. terebinthifolii. A further 14 new combinations are introduced in Diaporthe, and D. anacardii is epitypified. Although species of Diaporthe have in the past chiefly been distinguished based on host association, results of this study confirm several taxa to have wide host ranges, suggesting that they move freely among hosts, frequently co-colonising diseased or dead tissue. In contrast, some plant pathogenic and endophytic taxa appear to be strictly host specific. Given this diverse ecological behaviour among members of Diaporthe, future species descriptions lacking molecular data (at least ITS and HIS or TUB) should be strongly discouraged.

Keywords: internal transcribed spacer; south-africa; species concepts; sp-nov; coelomycete phomopsis; foeniculum-vulgare; multigene analysis; north-america; ribosomal dna; twig dieback

来源出版物: Persoonia, 2013, 31: 1–41联系邮箱: Crous, PW; p.crous@cbs.knaw.nl

NANOSCIENCE NANOTECHNOLOGY 纳米科学与纳米技术

被引频次: 228

Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Butler, SZ; Hollen, SM; Cao, LY; et al.

Abstract: Graphene's success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to preparesingle-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in field-effect transistors, spin- and valley-tronics, thermoelectrics, and topological insulators, among many other applications.

Keywords: chemical-vapor-deposition; der-waals epitaxy; hexagonal boron-nitride; single-layer mos2; field-effect transistors; transition-metal dichalcogenides; scanning-tunneling-microscopy; topological insulator nanoribbons; lithium intercalation properties; langmuir-blodgett deposition

来源出版物: Acs Nano, 2013, 7(4): 2898–2926联系邮箱: Goldberger, JE; goldberger@chemistry.ohio-state.edu

被引频次: 225

Raman spectroscopy as a versatile tool for studying the properties of graphene

Ferrari, AC; Basko, DM

Abstract: Raman spectroscopy is an integral part of graphene research. It is used to determine the number and orientation of layers, the quality and types of edge, and the effects of perturbations, such as electric and magnetic fields, strain, doping, disorder and functional groups. This, in turn, provides insight into all sp(2)-bonded carbon allotropes, because graphene is their fundamental building block. Here we review the state of the art, future directions and open questions in Raman spectroscopy of graphene. We describe essential physical processes whose importance has only recently been recognized, such as the various types of resonance at play, and the role of quantum interference. We update all basic concepts and notations, and propose a terminology that is able to describe any result in literature. We finally highlight the potential of Raman spectroscopy for layered materials other than graphene.

Keywords: carbon nanotubes; light-scattering; layer graphene; graphite; crystals; mode; electron; spectrum; films; band

来源出版物: Nature Nanotechnology, 2013, 8(4): 235–246联系邮箱: Ferrari, AC; acf26@eng.cam.ac.uk

被引频次: 200

Chemical Management for Colorful, Efficient, and Stable Inorganic-Organic Hybrid Nanostructured Solar Cells

Noh, JH; Im, SH; Heo, JH; et al.

Keywords: organometal halide perovskites; nanowires; crystals

来源出版物: Nano Letters, 2013, 13(4): 1764–1769联系邮箱: Seok, SI; seoksi@krict.re.kr

被引频次: 184

Sodium-Ion Batteries

Slater, MD; Kim, D; Lee, E; et al.

Abstract: The status of ambient temperature sodium ion batteries is reviewed in light of recent developments in anode, electrolyte and cathode materials. These devices, although early in their stage of development, are promising for large-scale grid storage applications due to the abundance and very low cost of sodium-containing precursors used to make the components. The engineering knowledge developed recently for highly successful Li ion batteries can be leveraged to ensure rapid progress in this area, although different electrode materials and electrolytes will be required for dual intercalation systems based on sodium. In particular, new anode materials need to be identified, since the graphite anode, commonly used in lithium systems, does not intercalate sodium to any appreciable extent. A wider array of choices is available for cathodes, including high performance layered transition metal oxides and polyanionic compounds. Recent developments in electrodes are encouraging, but a great deal of research is necessary, particularly in new electrolytes, and the understanding of the SEI films. The engineering modeling calculations of Na-ion battery energy density indicate that 210 Wh kg1 in gravimetric energy is possible for Na-ion batteries compared to existing Li-ion technology if a cathode capacity of 200 mAh g1 and a 500 mAh g1 anode can be discovered with an average cell potential of 3.3 V.

Keywords: rechargeable lithium batteries; electrochemical insertion; cathode material; nanocrystalline fe3o4; negative electrodes; petro-leum cokes; phase-diagram; na; intercalation; carbon

来源出版物: Advanced Functional Materials, 2013, 23(8): 947–958联系邮箱: Slater, MD; cjohnson@anl.gov

被引频次: 183

Memristive devices for computing

Yang, JJS; Strukov, DB; Stewart, DR

Abstract: Memristive devices are electrical resistance switches that can retain a state of internal resistance based on the history of applied voltage and current. These devices can store and process information, and offer several key performance characteristics that exceed conventional integrated circuit technology. An important class of memristive devices are two-terminal resistance switches based on ionic motion, which are built from a simple conductor/insulator/conductor thin-film stack. These devices were originally conceived in the late 1960s and recent progress has led to fast, low-energy, high-endurance devices that can be scaled down to less than 10 nm and stacked in three dimensions. However, the underlying device mechanisms remain unclear, which is a significant barrier to their widespread application. Here, we review recent progress in the development and understanding of memristive devices. We also examine the performance requirements for computing with memristive devices and detail how the outstanding challenges could be met.

Keywords: electrolyte nanometer switch; phase-change materials; memory devices; nonvolatile memory; resistive switches; oxide-films; neuromorphic architectures; conducting filament; atomic switch; doped srtio3

来源出版物: Nature Nanotechnology, 2013, 8(1): 13–24联系邮箱: Yang, JJS; jianhuay@hp.com

NEUROIMAGING 神经影像学

被引频次: 101

White matter integrity, fiber count, and other fallacies: The do's and don'ts of diffusion MRI

Jones, DK; Knosche, TR; Turner, R

Abstract: Diffusion-weighted MRI (DW-MRI) has been increasingly used in imaging neuroscience over the last decade. An early form of this technique, diffusion tensor imaging (DTI) was rapidly implemented by major MRI scanner companies as a scanner selling point. Due to the ease of use of such implementations, and the plausibility of some of their results. DTI was leapt on by imaging neuroscientists who saw it as a powerful and unique new tool for exploring the structural connectivity of human brain. However, DTI is a rather approximate technique, and its results have frequently been given implausible interpretations that have escaped proper critique and have appeared misleadingly in journals of high reputation. In order to encourage the use of improved DW-MRI methods, which have a better chance of characterizing the actual fiber structure of white matter, and to warn against the misuse and misinterpretation of DTI, we review the physics of DW-MRI, indicate currently preferred methodology, and explain the limits of interpretation of its results. We conclude with a list of 'Do's and Don'ts' which define good practice in this expanding area of imaging neuroscience.

Keywords: non-gaussian diffusion; human brain; tensor mri; water diffusion; in-vivo; weighted mri; spherical deconvolution; alzheimers-disease; gray-matter; orientation distributions

来源出版物: Neuroimage, 2013, 73: 239–254联系邮箱: Jones, DK; jonesd27@cardiff.ac.uk

被引频次: 86

An improved framework for confound regression and filtering for control of motion artifact in the preprocessing of resting-state functional connectivity data

Satterthwaite, TD; Elliott, MA; Gerraty, RT; et al.

Abstract: Several recent reports in large, independent samples have demonstrated the influence of motion artifact on resting-state functional connectivity MRI (rsfc-MRI). Standard rsfc-MRI preprocessing typically includes regression of confounding signals and band-pass filtering. However, substantial heterogeneity exists in how these techniques are implemented across studies, and no prior study has examined the effect of differing approaches for the control of motion-induced artifacts. To better understand how in-scanner head motion affects rsfc-MRI data, we describe the spatial, temporal, and spectral characteristics of motion artifacts in a sample of 348 adolescents. Analyses utilize a novel approach for describing head motion on a voxelwise basis. Next, we systematically evaluate the efficacy of a range of confound regression and filtering techniques for the control of motion-induced artifacts. Results reveal that the effectiveness of preprocessing procedures on the control of motion is heterogeneous, and that improved preprocessing provides a substantial benefit beyond typical procedures. These results demonstrate that the effect of motion on rsfc-MRI can be substantially attenuated through improved preprocessing procedures, but not completely removed.

Keywords: physiological noise correction; fmri time-series; human brain; cerebral-cortex; global signal; networks; fluctuations; optimization; model; anticorrelations

来源出版物: Neuroimage, 2013, 64: 240–256联系邮箱: Satterthwaite, TD; sattertt@upenn.edu

被引频次: 73

A comprehensive assessment of regional variation in the impact of head micromovements on functional connectomics

Yan, CG; Cheung, B; Kelly, C; et al.

Abstract: Functional connectomics is one of the most rapidly expanding areas of neuroimaging research. Yet, concerns remain regarding the use of resting-state fMRI (R-fMRI) to characterize inter-individual variation in the functional connectome. In particular, recent findings that "micro" head movements can introduce artifactual inter-individual and group-related differences in R-fMRI metrics have raised concerns. Here, we first build on prior demonstrations of regional variation in the magnitude of framewise displacements associated with a given head movement, by providing a comprehensive voxel-based examination of the impact of motion on the BOLD signal (i.e., motion-BOLD relationships). Positive motion-BOLD relationships were detected in primary and supplementary motor areas, particularly in low motion datasets. Negative motion-BOLD relationships were most prominent in prefrontal regions, and expanded throughout the brain in high motion datasets (e.g., children). Scrubbing of volumes with FD > 0.2 effectively removed negative but not positive correlations; these findings suggest that positive relationships may reflect neural origins of motion while negative relationships are likely to originate from motion artifact. We also examined the ability of motion correction strategies to eliminate artifactual differences related to motion among individuals and between groups for a broad array of voxel-wise R-fMRI metrics. Residual relationships between motion and the examined R-fMRI metrics remained for all correction approaches, underscoring the need to covary motion effects at the group-level. Notably, global signal regression reduced relationships between motion and inter-individual differences in correlation-based R-fMRI metrics; Z-standardization (mean-centering and variance normalization) of subject-level maps for R-fMRI metrics prior to group-level analyses demonstrated similar advantages. Finally, our test-retest (TRT) analyses revealed significant motion effects on TRT reliability for R-fMRI metrics. Generally, motion compromised reliability of R-fMRI metrics, with the exception of those based on frequency characteristics particularly, amplitude of low frequency fluctuations (ALFF). The implications of our findings for decision-making regarding the assessment and correction of motion are discussed, as are insights into potential differences among volume-based metrics of motion.

Keywords: prospective motion correction; fmri time-series; independent component analysis; resting-state fmri; human brain; connectivity mri; global signal; noise correction; networks; regression

来源出版物: Neuroimage, 2013, 76(1): 183–201联系邮箱: Milham, MP; Michael.Milham@childmind.org

被引频次: 44

The WU-Minn Human Connectome Project: An overview

Van Essen, DC; Smith, SM; Barch, DM; et al.

Abstract: The Human Connectome Project consortium led by Washington University, University of Minnesota, and Oxford University is undertaking a systematic effort to map macroscopic human brain circuits and their relationship to behavior in a large population of healthy adults. This overview article focuses on progress made during the first half of the 5-year project in refining the methods for data acquisition and analysis. Preliminary analyses based on a finalized set of acquisition and preprocessing protocols demonstrate the exceptionally high quality of the data from each modality. The first quarterly release of imaging and behavioral data via the ConnectomeDB database demonstrates the commitment to making HCP datasets freely accessible. Altogether, the progress to date provides grounds for optimism that the HCP datasets and associated methods and software will become increasingly valuable resources for characterizing human brain connectivity and function, their relationship to behavior, and their heritability and genetic underpinnings.

Keywords: intrinsic functional connectivity; independent component analysis; human brain; 7 tesla; fmri; signal; organization; tractography; networks; surface

来源出版物: Neuroimage, 2013, 80: 62–79联系邮箱: Van Essen, DC; vanessen@wustl.edu

被引频次: 42

Dynamic functional connectivity: Promise, issues, and interpretations

Hutchison, RM; Womelsdorf, T; Allen, EA; et al.

Abstract: The brain must dynamically integrate, coordinate, and respond to internal and external stimuli across multiple time scales. Non-invasive measurements of brain activity with fMRI have greatly advanced our understanding of the large-scale functional organization supporting these fundamental features of brain function. Conclusions from previous resting-state fMRI investigations were based upon static descriptions of functional connectivity (FC), and only recently studies have begun to capitalize on the wealth of information contained within the temporal features of spontaneous BOLD FC. Emerging evidence suggests that dynamic FC metrics may index changes in macroscopic neural activity patterns underlying critical aspects of cognition and behavior, though limitations with regard to analysis and interpretation remain. Here, we review recent findings, methodological considerations, neural and behavioral correlates, and future directions in the emerging field of dynamic FC investigations.

Keywords: resting-state networks; default-mode network; spontaneous brain activity; heart-rate-variability; independent component analy-sis; frequency bold fluctuations; fmri signal fluctuations; visual working-memory; propofol-induced loss; magnetic-resonance

来源出版物: Neuroimage, 2013, 80: 360–378联系邮箱: Hutchison, RM; rhutchis@uwo.ca

NEUROSCIENCES 神经科学

被引频次: 189

Power failure: why small sample size undermines the reliability of neuroscience

Button, KS; Ioannidis, JPA; Mokrysz, C; et al.

Abstract: A study with low statistical power has a reduced chance of detecting a true effect, but it is less well appreciated that low power also reduces the likelihood that a statistically significant result reflects a true effect. Here, we show that the average statistical power of studies in the neurosciences is very low. The consequences of this include overestimates of effect size and low reproducibility of results. There are also ethical dimensions to this problem, as unreliable research is inefficient and wasteful. Improving reproducibility in neuroscience is a key priority and requires attention to well-established but often ignored methodological principles.

Keywords: aneurysmal subarachnoid hemorrhage; randomized controlled-trials; alzheimers-disease; multiple-sclerosis; parkinsons-disease; gene polymorphisms; published research; cerebral-ischemia; clinical-trials; impact factor

来源出版物: Nature Reviews Neuroscience, 2013, 14(5): 365–376联系邮箱: Munafo, MR; marcus.munafo@bristol.ac.uk

被引频次: 123

The spectrum of disease in chronic traumatic encephalopathy

McKee, AC; Stein, TD; Nowinski, CJ; et al.

Abstract: Chronic traumatic encephalopathy is a progressive tauopathy that occurs as a consequence of repetitive mild traumatic brain injury. We analysed post-mortem brains obtained from a cohort of 85 subjects with histories of repetitive mild traumatic brain injury and found evidence of chronic traumatic encephalopathy in 68 subjects: all males, ranging in age from 17 to 98 years (mean 59.5 years), including 64 athletes, 21 military veterans (86% of whom were also athletes) and one individual who engaged in self-injurious head banging behaviour. Eighteen age- and gender-matched individuals without a history of repetitive mild traumatic brain injury served as control subjects. In chronic traumatic encephalopathy, the spectrum of hyperphosphorylated tau pathology ranged in severity from focal perivascular epicentres of neurofibrillary tangles in the frontal neocortex to severe tauopathy affecting widespread brain regions, including the medial temporal lobe, thereby allowing a progressive staging of pathology from stages I-IV. Multifocal axonal varicosities and axonal loss were found in deep cortex and subcortical white matter at all stages of chronic traumatic encephalopathy. TAR DNA-binding protein 43 immunoreactive inclusions and neurites were also found in 85% of cases, ranging from focal pathology in stages I-III to widespread inclusions and neurites in stage IV. Symptoms in stage I chronic traumatic encephalopathy included headache and loss of attention and concentration. Additional symptoms in stage II included depression, explosivity and short-term memory loss. In stage III, executive dysfunction and cognitive impairment were found, and in stage IV, dementia, word-finding difficulty and aggression were characteristic. Data on athletic exposure were available for 34 American football players; the stage of chronic traumatic encephalopathy correlated with increased duration of football play, survival after football and age at death. Chronic traumatic encephalopathy was the sole diagnosis in 43 cases (63%); eight were also diagnosed with motor neuron disease (12%), seven with Alzheimer's disease (11%), 11 with Lewy body disease (16%) and four with frontotemporal lobar degeneration (6%). There is an ordered and predictable progression of hyperphosphorylated tau abnormalities through the nervous system in chronic traumatic encephalopathy that occurs in conjunction with widespread axonal disruption and loss. The frequent association of chronic traumatic encephalopathy with other neurodegenerative disorders suggests that repetitive brain trauma and hyperphosphorylated tau protein deposition promote the accumulation of other abnormally aggregated proteins including TAR DNA-binding protein 43, amyloid beta protein and alpha-synuclein.

Keywords: frontotemporal lobar degeneration; amyotrophic-lateral-sclerosis; alzheimer-related changes; repetitive head-injury; football-league player; neuropathologic assessment; dementia-pugilistica; national institute; parkinson-disease; brain trauma

来源出版物: Brain, 2013, 136: 43–64联系邮箱: McKee, AC; ann.mckee@va.gov

被引频次: 118

On the free radical scavenging activities of melatonin's metabolites, AFMK and AMK

Galano, A; Tan, DX; Reiter, RJ

Abstract: The reactions of N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK) with center dot OH, center dot OOH, and center dot OOCCl3radicals have been studied using the density functional theory. Three mechanisms of reaction have been considered: radical adduct formation (RAF), hydrogen transfer (HT), and single electron transfer (SET). Their relative importance for the free radical scavenging activity of AFMK and AMK has been assessed. It was found that AFMK and AMK react with center dot OH at diffusion-limited rates, regardless of the polarity of the environment, which supports their excellent center dot OH radical scavenging activity. Both compounds were found to be also very efficient for scavenging center dot OOCCl3, but rather ineffective forscavenging center dot OOH. Regarding their relative activity, it was found that AFMK systematically is a poorer scavenger than AMK and melatonin. In aqueous solution, AMK was found to react faster than melatonin with all the studied free radicals, while in nonpolar environments, the relative efficiency of AMK and melatonin as free radical scavengers depends on the radical with which they are reacting. Under such conditions, melatonin is predicted to be a better center dot OOH and center dot OOCCl3scavenger than AMK, while AMK is predicted to be slightly better than melatonin for scavenging center dot OH. Accordingly it seems that melatonin and its metabolite AMK constitute an efficient team of scavengers able of deactivating a wide variety of reactive oxygen species, under different conditions. Thus, the presented results support the continuous protection exerted by melatonin, through the free radical scavenging cascade.

Keywords: reactive oxygen; in-vitro; antioxidative protection; density functionals; electron-transfer; brain metabolite; biogenic-amines; n-1-acetyl-5-methoxykynuramine; oxidation; dna

来源出版物: Journal of Pineal Research, 2013, 54(3): 245–257联系邮箱: Galano, A; agal@xanum.uam.mx

被引频次: 114

Allele-specific FKBP5 DNA demethylation mediates gene-childhood trauma interactions

Klengel, T; Mehta, D; Anacker, C; et al.

Abstract: Although the fact that genetic predisposition and environmental exposures interact to shape development and function of the human brain and, ultimately, the risk of psychiatric disorders has drawn wide interest, the corresponding molecular mechanisms have not yet been elucidated. We found that a functional polymorphism altering chromatin interaction between the transcription start site and long-range enhancers in the FK506 binding protein 5 (FKBP5) gene, an important regulator of the stress hormone system, increased the risk of developing stress-related psychiatric disorders in adulthood by allele-specific, childhood trauma-dependent DNA demethylation in functional glucocorticoid response elements of FKBP5. This demethylation was linked to increased stress-dependent gene transcription followed by a long-term dysregulation of the stress hormone system and a global effect on the function of immune cells and brain areas associated with stress regulation. This identification of molecular mechanisms of genotype-directed long-term environmental reactivity will be useful for designing more effective treatment strategies for stress-related disorders.

Keywords: posttraumatic-stress-disorder; early-life stress; glucocorticoid-receptor; adult depression; human genome; polymorphisms; abuse; methylation; moderation; risk

来源出版物: Nature Neuroscience, 2013, 16(1): 33–41联系邮箱: Klengel, T; klengel@mpipsykl.mpg.de

被引频次: 112

Unconventional Translation of C9ORF72 GGGGCC Expansion Generates Insoluble Polypeptides Specific to c9FTD/ALS

Ash, PEA; Bieniek, KF; Gendron, TF; et al.

Abstract: Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are devastating neurodegenerative disorders with clinical, genetic, and neuropathological overlap. Hexanucleotide (GGGGCC) repeat expansions in a noncoding region of C9ORF72 are the major genetic cause of FTD and ALS (c9FTD/ALS). The RNA structure of GGGGCC repeats renders these transcripts susceptible to an unconventional mechanism of translation repeat-associated non-ATG (RAN) translation. Antibodies generated against putative GGGGCC repeat RAN-translated peptides (anti-C9RANT) detected high molecular weight, insoluble material in brain homogenates, and neuronal inclusions throughout the CNS of c9FTD/ALS cases. C9RANT immunoreactivity was not found in other neurodegenerative diseases, including GAG repeat disorders, or in peripheral tissues of c9FTD/ALS. The specificity of C9RANT for c9FTD/ALS is a potential biomarker for this most common cause of FTD and ALS. These findings have significant implications for treatment strategies directed at RAN-translated peptides and their aggregation and the RNA structures necessary for their production.

Keywords: frontotemporal lobar degeneration; amyotrophic-lateral-sclerosis; hexanucleotide repeat expansion; rna; inclusions; disorders; spectrum; ftd; als

来源出版物: Neuron, 2013, 77(4): 639–646联系邮箱: Petrucelli, L; petrucelli.leonard@mayo.edu

NUCLEAR SCIENCE TECHNOLOGY 核科学与技术

被引频次: 55

The Large Underground Xenon (LUX) experiment

Akerib, DS; Bai, X; Bedikian, S; et al.

Abstract: The Large Underground Xenon (LUX) collaboration has designed and constructed a dual-phase xenon detector, in order to conduct a search for Weakly Interacting Massive Particles (WIMPs), a leading dark matter candidate. The goal of the LUX detector is to clearly detect (or exclude) WIMPS with a spin independent cross-section per nucleon of 2×10-46) cm2, equivalent to similar to 1 event 100 kg month in the inner 100 kg fiducial volume (FV) of the 370 kg detector. The overall background goals are set to have <1 background events characterized as possible WIMPs in the FV in 300 days of running.

This paper describes the design and construction of the LUX detector.

Keywords: dark-matter detector; zeplin-iii; gas

来源出版物: Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2013, 704: 111–126联系邮箱: Wolfs, FLH; wolfs@pas.rochester.edu

被引频次: 37

Recent progress in research on tungsten materials for nuclear fusion applications in Europe

Rieth, M; Dudarev, SL; de Vicente, SMG; et al.

来源出版物: Journal of Nuclear Materials, 2013, 432(1-3): 482–500联系邮箱: Rieth, M; Michael.rieth@kit.edu

被引频次: 28

Particle and Heavy Ion Transport code System, PHITS, version 2.52

Sato, T; Niita, K; Matsuda, N; et al.

Abstract: An upgraded version of the Particle and Heavy Ion Transport code System, PHITS2.52, was developed and released to the public. The new version has been greatly improved from the previously released version, PHITS2.24, in terms of not only the code itself but also the contents of its package, such as the attached data libraries. In the new version, a higher accuracy of simulation was achieved by implementing several latest nuclear reaction models. The reliability of the simulation was improved by modifying both the algorithms for the electron-, positron-, and photon-transport simulations and the procedure for calculating the statistical uncertainties of the tally results. Estimation of the time evolution of radioactivity became feasible by incorporating the activation calculation program DCHAIN-SP into the new package. The efficiency of the simulation was also improved as a result of the implementation of shared-memory parallelization and the optimization of several time-consuming algorithms. Furthermore, a number of new user-support tools and functions that help users to intuitively and effectively perform PHITS simulations were developed and incorporated. Due to these improvements, PHITS is now a more powerful tool for particle transport simulation applicable to various research and development fields, such as nuclear technology, accelerator design, medical physics, and cosmic-ray research.

Keywords: monte-carlo-simulation; accurate universal parameterization; reference computational phantoms; dose conversion coefficients; absorption cross-sections; proton-induced reactions; nuclear-science; model; improvement; neutrons

来源出版物: Journal of Nuclear Science and Technology, 2013, 50(9): 913–923联系邮箱: Sato, T; sato.tatsuhiko@jaea.go.jp

被引频次: 26

On the use of SRIM for computing radiation damage exposure

Stoller, RE; Toloczko, MB; Was, GS; et al.

Abstract: The SRIM (formerly TRIM) Monte Carlo simulation code is widely used to compute a number of parameters relevant to ion beam implantation and ion beam processing of materials. It also has the capability to compute a common radiation damage exposure unit known as atomic displacements per atom (dpa). Since dpa is a standard measure of primary radiation damage production, most researchers who employ ion beams as a tool for inducing radiation damage in materials use SRIM to determine the dpa associated with their irradiations. The use of SRIM for this purpose has been evaluated and comparisons have been made with an internationally-recognized standard definition of dpa, as well as more detailed atomistic simulations of atomic displacement cascades. Differences between the standard and SRIM-based dpa are discussed and recommendations for future usage of SRIM in radiation damage studies are made. In particular, it is recommended that when direct comparisons between ion and neutron data are intended, the Kinchin-Pease option of SRIM should be selected.

Keywords: displacement damage; defect production; irradiation; solids; metals; rates; atoms

来源出版物: Nuclear Instruments & Methods in Physics Research Section B–beam Interactions With Materials and Atoms, 2013, 310: 75–80联系邮箱: Stoller, RE; rkn@ornl.gov

被引频次: 23

Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

Matthews, GF

Abstract: Installation of the ITER-like Wall (ILW) in JET, has allowed a direct comparison of operation with all carbon plasma facing components (PFCs) to an all metal beryllium/tungsten first-wall under otherwise nearly identical conditions. The JET results are compared with experience from ASDEX-Upgrade where there was a gradual change to a full tungsten first-wall over an extended period. The scope of this review ranges from experience with machine conditioning, impurities and breakdown to material migration, fuel retention, disruptions, impact on operational space, energy confinement and compatibility with impurity seeding. Significant changes are reported, not only in the physics directly related to plasma-surface interactions but also to the main plasma which is strongly affected in unexpected ways, impacting many aspects of tokamak operation.

Keywords: asdex upgrade; divertor; migration; tungsten

来源出版物: Journal of Nuclear Materials, 2013, 438: S2–S10联系邮箱: Matthews, GF; gfm@jet.uk

NURSING 护理学

被引频次: 21

Patient risk factors for pressure ulcer development: Systematic review

Coleman, S; Gorecki, C; Nelson, EA; et al.

Abstract: Objective: To identify risk factors independently predictive of pressure ulcer development in adult patient populations?

Design: A systematic review of primary research was undertaken, based upon methods recommended for effectiveness questions but adapted to identify observational risk factor studies.

Data sources: Fourteen electronic databases were searched, each from inception until March 2010, with hand searching of specialist journals and conference proceedings; contact with experts and a citation search. There was no language restriction.

Review methods: Abstracts were screened, reviewed against the eligibility criteria, data extracted and quality appraised by at least one reviewer and checked by a second. Where necessary, statistical review was undertalcen. We developed an assessment framework and quality classification based upon guidelines for assessing quality and methodological considerations in the analysis, meta-analysis and publication of observational studies. Studies were classified as high, moderate, low and very low quality. Risk factors were categorised into risk factor domains and sub-domains. Evidence tables were generated and a summary narrative synthesis by sub-domain and domain was undertaken. Results: Of 5462 abstracts retrieved, 365 were identified as potentially eligible and 54 fulfilled the eligibility criteria. The 54 studies included 34,449 patients and acute and community patient populations. Seventeen studies were classified as high or moderate quality, whilst 37 studies (68.5%) had inadequate numbers of pressure ulcers and other methodological limitations. Risk factors emerging most frequently as independent predictors of pressure ulcer development included three primary domains of mobility/activity, perfusion (including diabetes) and skin/pressure ulcer status. Skin moisture, age, haematological measures, nutrition and general health status are also important, but did not emerge as frequently as the three main domains. Body temperature and immunity may be important but require further confirmatory research. There is limited evidence that either race or gender is important.

Conclusions: Overall there is no single factor which can explain pressure ulcer risk, rather a complex interplay of factors which increase the probability of pressure ulcer development. The review highlights the limitations of over-interpretation of results from individual studies and the benefits of reviewing results from a number of studies to develop a more reliable overall assessment of factors which are important in affecting patient susceptibility.

Keywords: nursing-home residents; intensive-care-unit; critically-ill patients; hospitalized-patients; prognostic-factors; support surfaces; braden scale; sores; surgery; regression

来源出版物: International Journal of Nursing Studies, 2013, 50(7): 974–1003联系邮箱: Coleman, S; medscole@leeds.ac.uk

被引频次: 19

Living Quality: A Humanbecoming Phenomenon

Parse, RR

Abstract: The purpose of this article is to set forth the humanbecoming paradigm and the phenomenon living quality, which better expresses the notion of quality of life from this paradigmatic perspective. The three inherent core knowings of living quality are described and explained in light of the community change concepts. Living quality with sciencing and living the art of humanbecoming are also discussed.

Keywords: human becoming perspective; of-life; retirement; community; cancer; health; women; art

来源出版物: Nursing Science Quarterly, 2013, 26(2): 111–115

被引频次: 18

Outcomes of Care in Birth Centers: Demonstration of a Durable Model

Stapleton, SR; Osborne, C; Illuzzi, J

Abstract: Introduction: The safety and effectiveness of birth center care have been demonstrated in previous studies, including the National Birth Center Study and the San Diego Birth Center Study. This study examines outcomes of birth center care in the present maternity care environment. Methods: This was a prospective cohort study of women receiving care in 79 midwifery-led birth centers in 33 US states from 2007 to 2010. Data were entered into the American Association of Birth Centers Uniform Data Set after obtaining informed consent. Analysis was by intention to treat, with descriptive statistics calculated for maternal and neonatal outcomes for all women presenting to birth centers in labor including those requiring transfer to hospital care. Results: Of 15,574 women who planned and were eligible for birth center birth at the onset of labor, 84% gave birth at the birth center. Four percent were transferred to a hospital prior to birth center admission, and 12% were transferred in labor after admission. Regardless of where they gave birth, 93% of women had a spontaneous vaginal birth, 1% an assisted vaginal birth, and 6% a cesarean birth. Of women giving birth in the birth center, 2.4% required transfer postpartum, whereas 2.6% of newborns were transferred after birth. Most transfers were nonemergent, with 1.9% of mothers or newborns requiring emergent transfer during labor or after birth. There were no maternal deaths. The intrapartum fetal mortality rate for women admitted to the birth center in labor was 0.47/1000. The neonatal mortality rate was 0.40/1000 excluding anomalies. Discussion: This study demonstrates the safety of the midwifery-led birth center model of collaborative care as well as continued low obstetric intervention rates, similar to previous studies of birth center care. These findings are particularly remarkable in an era characterized by increases in obstetric intervention and cesarean birth nationwide.

Keywords: cesarean-section rate; risk; complications; cohort

来源出版物: Journal of Midwifery & Womens Health, 2013, 58(1): 3–14联系邮箱: Stapleton, SR; susanstapleton71@gmail.com

被引频次: 16

Content analysis and thematic analysis: Implications for conducting a qualitative descriptive study

Vaismoradi, M; Turunen, H; Bondas, T

Abstract: Qualitative content analysis and thematic analysis are two commonly used approaches in data analysis of nursing research, but boundaries between the two have not been clearly specified. In other words, they are being used interchangeably and it seems difficult for the researcher to choose between them. In this respect, this paper describes and discusses the boundaries between qualitative content analysis and thematic analysis and presents implications to improve the consistency between the purpose of related studies and the method of data analyses. This is a discussion paper, comprising an analytical overview and discussion of the definitions, aims, philosophical background, data gathering, and analysis of content analysis and thematic analysis, and addressing their methodological subtleties. It is concluded that in spite of many similarities between the approaches, including cutting across data and searching for patterns and themes, their main difference lies in the opportunity for quantification of data. It means that measuring the frequency of different categories and themes is possible in content analysis with caution as a proxy for significance.

Keywords: research proposals; nursing-research; trustworthiness

来源出版物: Nursing & Health Sciences, 2013, 15(3): 398–405联系邮箱: Turunen, H; hannele.turunen@uef.fi

被引频次: 13

Mobile Phone Interventions to Increase Physical Activity and Reduce Weight A Systematic Review

Stephens, J; Allen, J

Abstract: Objective: This systematic review was conducted to determine user satisfaction and effectiveness of smartphone applications and text messaging interventions to promote weight reduction and physical activity. Methods: Studies of smartphone applications and text messaging interventions related to the cardiovascular risk factors of physical inactivity and overweight/obesity published between January 2005 and August 2010 were eligible. Studies related to disease management were excluded. Study characteristics and results were gathered and synthesized. Results: A total of 36 citations from CINAHL, EMBASE, MEDLINE, PsycINFO, and PubMed were identified; 7 articles were eligible for inclusion. The most frequent outcome measured in the studies was change in the weight of participants (57%). More than half of the studies (71%) reported statistically significant results in at least 1 outcome of weight loss, physical activity, dietary intake, decreased body mass index, decreased waist circumference, sugar-sweetened beverage intake, screen time, and satisfaction or acceptability outcomes. Conclusions: All of the technology interventions that were supported by education or an additional intervention demonstrated a beneficial impact of text messaging or smartphone application for reduction of physical inactivity and/or overweight/obesity. More rigorous trials that determine what parts of the technology or intervention are effective as well as establishment of cost-effectiveness are necessary for further evaluation of smartphone and text messaging interventions.

Keywords:

来源出版物: Journal of Cardiovascular Nursing, 2013, 28(4): 320–329联系邮箱: Stephens, J; jsteph22@son.jhmi.edu

NUTRITION DIETETICS 营养学

被引频次: 54

Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes

Ajala, O; English, P; Pinkney, J

Abstract: Background: There is evidence that reducing blood glucose concentrations, inducing weight loss, and improving the lipid profile reduces cardiovascular risk in people with type 2 diabetes.

Objective: We assessed the effect of various diets on glycemic control, lipids, and weight loss.

Design: We conducted searches of PubMed, Embase, and Google Scholar to August 2011. We included randomized controlled trials (RCTs) with interventions that lasted≥6 mo that compared low-carbohydrate, vegetarian, vegan, low glycemic index (GI), high-fiber, Mediterranean, and high-protein diets with control diets including low-fat, high-GI, American Diabetes Association, European Association for the Study of Diabetes, and low-protein diets.

Results: A total of 20 RCTs were included (n=3073 included in final analyses across 3460 randomly assigned individuals). The low-carbohydrate, low-GI, Mediterranean, and high-protein diets all led to a greater improvement in glycemic control [glycated hemoglobin reductions of -0.12% (P=0.04), -0.14% (P=0.008), -0.47% (P<0.00001), and -0.28% (P<0.00001), respectively] compared with their respective control diets, with the largest effect size seen in the Mediterranean diet. Low-carbohydrate and Mediterranean diets led to greater weight loss [0.69 kg (P=0.21) and 1.84 kg (P<0.00001), respectively], with an increase in HDL seen in all diets except the high-protein diet.

Conclusion: Low-carbohydrate, low-GI, Mediterranean, and high-protein diets are effective in improving various markers of cardiovascular risk in people with diabetes and should be considered in the overall strategy of diabetes management.

Keywords: low-glycemic-index; low-fat diet; low-carbohydrate diet; cardiovascular risk-factors; randomized clinical-trial; high-monounsaturated fat; mediterranean-style diet; high-protein-diet; weight-loss diet; follow-up

来源出版物: American Journal of Clinical Nutrition, 2013, 97(3): 505–516联系邮箱: Ajala, O; olubukola.ajala@nhs.net

被引频次: 39

Update of the Healthy Eating Index: HEI-2010

Guenther, PM; Casavale, KO; Reedy, J et al.

Abstract: The Healthy Eating Index (HEI) is a measure of diet quality in terms of conformance with federal dietary guidance. Publication of the 2010 Dietary Guidelines for Americans prompted an interagency working group to update the HEI. The HEI-2010 retains several features of the 2005 version: (a) it has 12 components, many unchanged, including nine adequacy and three moderation components; (b) it uses a density approach to set standards, eg, per 1,000 calories or as a percentage of calories; and (c) it employs least-restrictive standards; ie, those that are easiest to achieve among recommendations that vary by energy level, sex, and/or age. Changes to the index include: (a) the Greens and Beans component replaces Dark Green and Orange Vegetables and Legumes; (b) Seafood and Plant Proteins has been added to capture specific choices from the protein group; (c) Fatty Acids, a ratio of polyunsaturated and monounsaturated to saturated fatty acid's, replaces Oils and Saturated Fat to acknowledge the recommendation to replace, saturated fat with monounsaturated and polyunsaturated fatty acids; and (d) a moderation component, Refined Grains, replaces the adequacy component, Total Grains, to assess overconsumption. The HEI-2010 captures the key recommendations of the 2010 Dietary Guidelines and, like earlier versions, will be used to assess the diet quality of the US population and subpopulations, evaluate interventions, research dietary patterns, and evaluate various aspects of the food environment.

Keywords: nutrient-rich foods; one 24-hour recall; diet-quality; colorectal-cancer; blood-pressure; older-adults; united-states; weight status; dash-sodium; risk

来源出版物: Journal of The Academy of Nutrition and Dietetics, 2013, 113(4): 569–580

联系邮箱: Guenther, PM; Patricia.Guenther@cnpp.usda.gov

被引频次: 38

Vitamin D-Effects on Skeletal and Extraskeletal Health and the Need for Supplementation

Wacker, M; Holick, MF

Abstract: Vitamin D, the sunshine vitamin, has received a lot of attention recently as a result of a meteoric rise in the number of publications showing that vitamin D plays a crucial role in a plethora of physiological functions and associating vitamin D deficiency with many acute and chronic illnesses including disorders of calcium metabolism, autoimmune diseases, some cancers, type 2 diabetes mellitus, car-diovascular disease and infectious diseases. Vitamin D deficiency is now recognized as a global pandemic. The major cause for vitamin D deficiency is the lack of appreciation that sun exposure has been and continues to be the major source of vitamin D for children and adults of all ages. Vitamin D plays a crucial role in the development and maintenance of a healthy skeleton throughout life. There remains some controversy regarding what blood level of 25-hydroxyvitamin D should be attained for both bone health and reducing risk for vitamin D deficiency associated acute and chronic diseases and how much vitamin D should be supplemented.

Keywords: serum 25-hydroxyvitamin d; randomized controlled-trial; intestinal calcium-absorption; respiratory-tract infection; d-receptor polymorphisms; placebo-controlled trial; chronic kidney-disease; cod-liver oil; d deficiency; rheumatoid-arthritis

来源出版物: Nutrients, 2013, 5(1): 111–148联系邮箱: Holick, MF; mwacker@bu.edu

被引频次: 35

Etiology of the Protein-Energy Wasting Syndrome in Chronic Kidney Disease: A Consensus Statement From the International Society of Renal Nutrition andMetabolism (ISRNM)

Carrero, JJ; Stenvinkel, P; Cuppari, L; et al.

Abstract: Protein-energy wasting (PEW), a term proposed by the International Society of Renal Nutrition and Metabolism (ISRNM), refers to the multiple nutritional and catabolic alterations that occur in chronic kidney disease (CKD) and associate with morbidity and mortality. To increase awareness, identify research needs, and provide the basis for future work to understand therapies and consequences of PEW, ISRNM provides this consensus statement of current knowledge on the etiology of PEW syndrome in CKD. Although insufficient food intake (true undernutrition) due to poor appetite and dietary restrictions contribute, other highly prevalent factors are required for the full syndrome to develop. These include uremia-induced alterations such as increased energy expenditure, persistent inflammation, acidosis, and multiple endocrine disorders that render a state of hypermetabolism leading to excess catabolism of muscle and fat. In addition, comorbid conditions associated with CKD, poor physical activity, frailty, and the dialysis procedure per se further contribute to PEW. Published by Elsevier Inc. on behalf of the National Kidney Foundation, Inc.

Keywords: chronic-hemodialysis patients; peritoneal-dialysis patients; skeletal-muscle atrophy; low serum testosterone; amino-acid oxidation; insulin-resistance; metabolic-acidosis; dietary-protein; body-mass; endothelial dysfunction

来源出版物: Journal of Renal Nutrition, 2013, 23(2): 77–90联系邮箱: Franch, HA; hfranch@emory.edu

被引频次: 34

Clinical Practice Guidelines for the Perioperative Nutritional, Metabolic, and Nonsurgical Support of the Bariatric Surgery Patient-2013 Update: Cosponsored by American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery

Mechanick, JI; Youdim, A; Jones, DB; et al.

Abstract: The development of these updated guidelines was commissioned by the AACE, TOS, and ASMBS Board of Directors and adheres to the AACE 2010 protocol for standardized production of clinical practice guidelines (CPG). Each recommendation was re-evaluated and updated based on the evidence and subjective factors per protocol. Examples of expanded topics in this update include: the roles of sleeve gastrectomy, bariatric surgery in patients with type-2 diabetes, bariatric surgery for patients with mild obesity, copper deficiency, informed consent, and behavioral issues. There are 74 recommendations (of which 56 are revised and 2 are new) in this 2013 update, compared with 164 original recommendations in 2008. There are 403 citations, of which 33 (8.2%) are EL 1131 (32.5%) are EL 2170 (42.2%) are EL 3, and 69 (17.1%) are EL 4. There is a relatively high proportion (40.4%) of strong (EL 1 and 2) studies, compared with only 16.5% in the 2008 AACE-TOS-ASMBS CPG. These updated guidelines reflect recent additions to the evidence base. Bariatric surgery remains a safe and effective intervention for select patients with obesity. A team approach to perioperative care is mandatory with special attention to nutritional and metabolic issues.

Keywords: y-gastric-bypass; laparoscopic-sleeve-gastrectomy; type-2 diabetes-mellitus; weight-loss surgery; body-mass index; prospective-randomized-trial; of-the-literature; outcomes longitudinal database; helicobacter-pylori infection; cardiovascular risk-factors

来源出版物: Obesity, 2013, 21: S1–S27联系邮箱: Mechanick, JI; jeffreymechanick@gmail.com

OBSTETRICS GYNECOLOGY 妇产科学

被引频次: 53

Restoration of ovarian activity and pregnancy after transplantation of cryopreserved ovarian tissue: a review of 60 cases of reimplantation

Donnez, J; Dolmans, MM; Pellicer, A; et al.

Abstract: Aggressive chemotherapy/radiotherapy and bone marrow transplantation can cure >90% of girls and young women affected by disorders requiring such treatment. However, the ovaries are very sensitive to cytotoxic drugs, especially to alkylating agents. Several op-tions are currently available to preserve fertility in cancer patients. The present review reports the results of 60 orthotopic reimplantations of cryopreserved ovarian tissue performed by three teams, as well as 24 live births reported in the literature to date. Restoration of ovarian activity occurred in almost all cases in the three series. Among the 60 patients, eleven conceived and six of those had already delivered twelve healthy babies. In the future, we are looking to: 1) improve freezing techniques; and 2) enhance the "vascular bed'' before reimplantation to increase pregnancy rates. On the other hand, cryopreservation of ovarian tissue may be combined with removal, via puncture, of small antral follicles, making it possible to freeze both ovarian tissue and isolated immature oocytes.

Keywords: monozygotic twins discordant; bone-marrow-transplantation; pre-antral follicles; fertility preservation; live birth; follicular-growth; oocyte retrieval; cortical tissue; young-patients; failure

来源出版物: Fertility and Sterility, 2013, 99(6): 1503–1513联系邮箱: Donnez, J; jacques.donnez@gmail.com

被引频次: 53

2012 Updated Consensus Guidelines for the Management of Abnormal Cervical Cancer Screening Tests and Cancer Precursors

Massad, LS; Einstein, MH; Huh, WK; et al.

Abstract: A group of 47 experts representing 23 professional societies, national and international health organizations, and federal agencies met in Bethesda, MD, September 14-15, 2012, to revise the 2006 American Society for Colposcopy and Cervical Pathology Consensus Guidelines. The group's goal was to provide revised evidence-based consensus guidelines for managing women with abnormal cervical cancer screening tests, cervical intraepithelial neoplasia (CIN) and adenocarcinoma in situ (AIS) following adoption of cervical cancer screening guidelines incorporating longer screening intervals and co-testing. In addition to literature review, data from almost 1.4 million women in the Kaiser Permanente Northern California Medical Care Plan provided evidence on risk after abnormal tests. Where data were available, guidelines prescribed similar management for women with similar risks for CIN 3, AIS, and cancer. Most prior guidelines were reaffirmed. Examples of updates include: Human papillomavirus-negative atypical squamous cells of undetermined significance results are followed with co-testing at 3 years before return to routine screening and are not sufficient for exiting women from screening at age 65 years; women aged 21-24 years need less invasive management, especially for minor abnormalities; postcolposcopy management strategies incorporate co-testing; endocervical sampling reported as CIN 1 should be managed as CIN 1; unsatisfactory cytology should be repeated in most circumstances, even when HPV results from co-testing are known, while most cases of negative cytology with absent or insufficient endocervical cells or transformation zone component can be managed without intensive follow-up.

Keywords: adenocarcinoma in-situ; squamous intraepithelial lesions; human-papillomavirus infection; atypical glandular cells; of-american-pathologists; undetermined significance; endocervical curettage; randomized-trial; uterine cervix; young-women

来源出版物: Obstetrics and Gynecology, 2013, 121(4): 829–846联系邮箱: Massad, LS; massadl@wudosis.wustl.edu

被引频次: 44

2012 Updated Consensus Guidelines for the Management of Abnormal Cervical Cancer Screening Tests and Cancer Precursors

Massad, LS; Einstein, MH; Huh, WK; et al.

Abstract: A group of 47 experts representing 23 professional societies, national and international health organizations, and federal agencies met in Bethesda, MD, September 14-15, 2012, to revise the 2006 American Society for Colposcopy and Cervical Pathology Consensus Guidelines. The group's goal was to provide revised evidence-based consensus guidelines for managing women with abnormal cervical cancer screening tests, cervical intraepithelial neoplasia (CIN) and adenocarcinoma in situ (AIS) following adoption of cervical cancer screening guidelines incorporating longer screening intervals and co-testing. In addition to literature review, data from almost 1.4 million women in the Kaiser Permanente Northern California Medical Care Plan provided evidence on risk after abnormal tests. Where data were available, guidelines prescribed similar management for women with similar risks for CIN 3, AIS, and cancer. Most prior guidelines were reaffirmed. Examples of updates include: Human papillonnavirus negative atypical squamous cells of undetermined significance results are followed with co-testing at 3 years before return to routine screening and are not sufficient for exiting women from screening at age 65 years; women aged 21-24 years need less invasive management, especially for minor abnormalities; postcolposcopy management strategies incorporate co-testing; endocervical sampling reported as CIN 1 should be managed as CIN 1; unsatisfactory cytology should be repeated in most circumstances, even when HPV results from co-testing are known, while most cases of negative cytology with absent or insufficient endocervical cells or transformation zone component can be managed without intensive follow-up.

来源出版物: Journal of Lower Genital Tract Disease, 2013, 17: S1–S27联系邮箱: Massad, LS; massadl@wudosis.wustl.edu

被引频次: 44

Why do singletons conceived after assisted reproduction technology have adverse perinatal outcome? Systematic review and meta-analysis

Pinborg, A; Wennerholm, UB; Romundstad, LB; et al.

Abstract: BACKGROUND: Assisted reproduction technology (ART) is used worldwide, at increasing rates, and data show that some adverse outcomes occur more frequently than following spontaneous conception (SC). Possible explanatory factors for the well-known adverse perinatal outcome in ART singletons were evaluated.

METHODS: PubMed and Cochrane databases from 1982 to 2012 were searched. Studies using donor or frozen oocytes were excluded, as well as those with no control group or including <100 children. The main outcome measure was preterm birth (PTB defined as delivery <37 weeks of gestation), and a random effects model was used for meta-analyses of PTB. Other outcomes were very PTB, low-birthweight (LBW), very LBW, small for gestational age and perinatal mortality.

RESULTS: The search returned 1255 articles and 65 of these met the inclusion criteria. The following were identified as predictors for PTB in singletons: SC in couples with time to pregnancy (TTP) > I year versus SC singletons in couples with TTP≤1 year [adjusted odds ratio (AOR) 1.35, 95% confidence interval (CI) 1.22, 1.50]; IVF/ICSI versus SC singletons from subfertile couples (TTP > 1 year; AOR 1.55, 95% CI 1.30, 1.85); conception after ovulation induction and/or intrauterine insemination versus SC singletons where TTP < 1 year (AOR 1.45, 95% CI 1.21, 1.74); IVF/ICSI singletons versus their non-ART singleton siblings (AOR 1.27, 95% CI 1.08, 1.49). The risk of PTB in singletons with a 'vanishing co-twin' versus from a single gestation was AOR of 1.73 (95% CI 1.54, 1.94) in the narrative data. ICSI versus IVF (AOR 0.80, 95% CI 0.69-0.93), and frozen embryo transfer versus fresh embryo transfer (AOR 0.85, 95% CI 0.76, 0.94) were associated with a lower risk of PTB.

CONCLUSIONS: Subfertility is a major risk factor for adverse perinatal outcome in ART singletons, however, even in the same mother an ART singleton has a poorer outcome than the non-ART sibling; hence, factors related to the hormone stimulation and/or IVF methods per se also may play a part. Further research is required into mechanisms of epigenetic modification in human embryos and the effects of cryo-preservation on this, whether milder ovarian stimulation regimens can improve embryo quality and endometrial conditions, and whether longer culture times for embryos has a negative influence on the perinatal outcome.

Keywords: in-vitro fertilization; low-birth-weight; double-embryo-transfer; intracytoplasmic sperm injection; long-term health; ovarian stimulation; oocyte donation; increased risk; children born; cryopreserved embryos

来源出版物: Human Reproduction Update, 2013, 19(2): 87–104联系邮箱: Pinborg, A; pinborg@nru.dk

被引频次: 42

Competing Risks Model in Early Screening for Preeclampsia by Biophysical and Biochemical Markers

Akolekar, R; Syngelaki, A; Poon, L; et al.

Abstract: Objective: To develop models for prediction of preeclampsia (PE) based on maternal characteristics, biophysical and biochemical markers at 11-13 weeks' gestation in which the gestation at the time of delivery for PE is treated as a continuous variable. Methods:This was a screening study of singleton pregnancies at 11-13 weeks including 1426 (2.4%) that subsequently developed PE and 57458 that were unaffected by PE. We developed a survival time model for the time of delivery for PE in which Bayes' theorem was used to combine the prior information from maternal characteristics with uterine artery pulsatility index (PI), mean arterial pressure (MAP), serum pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PLGF) multiple of the median (MoM) values. Results: In pregnancies with PE, there was a linear correlation between MoM values of uterine artery PI, MAP, PAPP-A and PLGF with gestational age at delivery and therefore the deviation from normal was greater for early than late PE for all four biomarkers. Screening by maternal characteristics, biophysical and biochemical markers detected 96% of cases of PE requiring delivery before 34 weeks and 54% of all cases of PE at a fixed false-positive rate of 10%. Conclusions: A new model has been developed for effective first-trimester screening for PE.

Keywords: intrauterine growth restriction; 11-13 weeks gestation; plasma protein-a; hypertensive disorders; pregnancy; prediction; prevention; trisomy-21; aspirin

来源出版物: Fetal Diagnosis and Therapy, 2013, 33(1): 8–15联系邮箱: Nicolaides, KH; kypros.nicolaides@kcl.ac.uk

(责任编辑姚玉琴)

Studies of Li-Air Cells Utilizing Dimethyl Sulfoxide-Based Electrolyte

Trahan, MJ; Mukerjee, S; Plichta, EJ; et al.

Dimethyl Sulfoxide (DMSO) was evaluated as a practical solvent for the rechargeable lithium air battery. Redox characteristics of the dissolved oxygen and its reduction products in the presence of lithium hexafluorophosphate (LiPF6) supporting electrolyte were studied via cyclic, rotating disk (RDE) and ring-disk (RRDE) electrode voltammetry. The DMSO medium facilitates reversible reduction and oxidation processes in contrast to other solvent-based electrolytes studied. Galvanostatic discharge-charge cycling of the Li-O2cells has shown characteristics of rechargeability expected from voltammetric studies. Multiple high-efficiency discharge-charge cycles are possible if the depth of discharge of the carbon cathode is limited to avoid excessive passivation by the discharge products. The discharge voltage of this Li-O2cell is higher than cells assembled with other non-aqueous organic electrolytes, an attribute ascribed to the stability of superoxide (O2-), the one-electron reduction product of oxygen.

lithium-oxygen battery; ionic liquid; carbonate electrolytes; polymer electrolyte; Li-O2batteries; reduction; stability; products; ether