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Electrochemical Activation of Li2MnO3 Electrodes at 0 °c and Its Impact on the Subsequent Performance at Higher Temperatures

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MATERIALS 2020年第19期13卷 4388页

作者： Susai, Francis Amalraj Talianker, Michael Liu, Jing Rosy Paul, Tanmoy Grinblat, Yehudit Erickson, Evan Noked, Malachi Burstein, Larisa Frenkel, Anatoly I. Tsur, Yoed Markovsky, Boris Aurbach, Doron Bar Ilan Univ Dept Chem IL-52900 Ramat Gan Israel Bar Ilan Univ Inst Nanotechnol & Adv Mat IL-52900 Ramat Gan Israel Ben Gurion Univ Negev Dept Mat Engn IL-84105 Beer Sheva Israel Manhattan Coll Dept Phys New York NY 10471 USA Technion Israel Inst Technol Dept Chem Engn IL-3200003 Haifa Israel Technion Israel Inst Technol Grand Technion Energy Program IL-3200003 Haifa Israel Tel Aviv Univ Wolfson Appl Mat Res Ctr IL-69978 Tel Aviv Israel SUNY Stony Brook Dept Mat Sci & Chem Engn Stony Brook NY 11794 USA

This work continues our systematic study of Li- and Mn- rich cathodes for lithium-ion batteries. We chose Li2MnO3 as a model electrode material with the aim of correlating the improved electrochemical characteristics of these cathodes initially activated at 0 degrees c with the structural evolution of Li2MnO3, oxygen loss, formation of per-oxo like species (O-2(2-)) and the surface chemistry. It was established that performing a few initial charge/discharge (activation) cycles of Li2MnO3 at 0 degrees c resulted in increased discharge capacity and higher capacity retention, and decreased and substantially stabilized the voltage hysteresis upon subsequent cycling at 30 degrees c or at 45 degrees c. In contrast to the activation of Li2MnO3 at these higher temperatures, Li2MnO3 underwent step-by-step activation at 0 degrees c, providing a stepwise traversing of the voltage plateau at >4.5 V during initial cycling. Importantly, these findings agree well with our previous studies on the activation at 0 degrees c of 0.35Li(2)MnO(3)center dot 0.65Li[Mn0.45Ni0.35co0.20]O-2 materials. The stability of the interface developed at 0 degrees c can be ascribed to the reduced interactions of the per-oxo-like species formed and the oxygen released from Li2MnO3 with solvents in ethylene carbonate-methyl-ethyl carbonate/LiPF6 solutions. Our TEM studies revealed that typically, upon initial cycling both at 0 degrees c and 30 degrees c, Li2MnO3 underwent partial structural layered-to-spinel (Li2Mn2O4) transition.

关键词： lithium-ion batteries Li and Mn-rich materials Li2MnO3 activation at 0 ° c stabilized cycling decreased the voltage hysteresis layered-to-spinel transition bulk and surface characteristics

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Advanced control-flow and concurrency in c∀

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SOFTWARE-PRAcTIcE & EXPERIENcE 2021年第5期51卷 1005-1042页

作者： Delisle, Thierry Buhr, Peter A. Univ Waterloo Cheriton Sch Comp Sci 200 Univ Ave West Waterloo ON N2L 3G1 Canada

c for all is a polymorphic, nonobject-oriented, concurrent, backwards compatible extension of the c programming language. This paper discusses the design philosophy and implementation of its advanced control-flow and concurrent/parallel features, along with the supporting runtime written in c for all. These features are created from scratch as ISO c has only low-level and/or unimplemented concurrency, so c programmers continue to rely on library approaches like pthreads. c for all introduces modern language-level control-flow mechanisms, like generators, coroutines, user-level threading, and monitors for mutual exclusion and synchronization. The runtime provides significant programmer simplification and safety by eliminating spurious wakeup and monitor barging. The runtime also ensures multiple monitors can be safely acquired in a deadlock-free way, and this feature is fully integrated with all monitor synchronization mechanisms. All control-flow features integrate with the c for all polymorphic type-system and exception handling, while respecting the expectations and style of c programmers. Experimental results show comparable performance of the new features with similar mechanisms in other concurrent programming languages.

关键词： c c∀ (cforall) coroutine concurrency generator monitor parallelism runtime thread

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MULTIPLE-TAPER SPEcTRAL-ANALYSIS - A STAND-ALONE c-SUBROUTINE

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cOMPUTERS & GEOScIENcES 1995年第2期21卷 199-236页

作者： LEES, JM PARK, J Department of Geology and Geophysics Yale University P.O. Box 208109 New Haven CT 06520-8109 U.S.A.

A simple set of subroutines in ANSI-c are presented for multiple taper spectrum estimation. The multitaper approach provides an optimal spectrum estimate by minimizing spectral leakage while reducing the variance of the estimate by averaging orthogonal eigenspectrum estimates. The orthogonal tapers are Slepian n pi prolate functions used as tapers on the windowed time series. Because the taper functions are orthogonal, combining them to achieve an average spectrum does not introduce spurious correlations as standard smoothed single-taper estimates do. Furthermore, estimates of the degrees of freedom and F-test values at each frequency provide diagnostics for determining levels of confidence in narrow band (single frequency) periodicities. The program provided is portable and has been tested on both Unix and Macintosh systems.

关键词： SPEcTRAL ANALYSIS MULTITAPER SPEcTRUM GEOLOGIcAL TIME SERIES c

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Superior hydrogen generation from sodium borohydride hydrolysis catalyzed by the bimetallic co-Ru/c nanocomposite

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2021年第50期46卷 25376-25384页

作者： Huang, Wenkai Xu, Fuhua Liu, Xiang China Three Gorges Univ Engn Res Ctr Ecoenvironm Three Gorges Reservoir R Key Lab Inorgan Nonmetall Crystalline & Energy Co Coll Mat & Chem EngnMinist Educ Yichang 443002 Hubei Peoples R China

Sodium borohydride has been widely regarded as a promising hydrogen carrier owing to its greatly hydrogen storing capability (10.8 wt%), high weight density and excellent stability in alkaline solutions. Herein, we first design and synthesize a series of bimetallic M-Ru/c nanocomposites (including Fe-Ru/c, co-Ru/c, Ni-Ru/c and cu-Ru/c), via simply alloying of commercial Ru/c with nonprecious metal, for superior H2 evolution from the NaBH4 hydrolysis. The result exhibits that H2 generation is synergetically improved by alloying Ru/ c with co or Ni, while it is hindered by alloying Ru/c with Fe or cu. Indeed, co-Ru/c presents the highest efficient catalytic activity for H2 generation, with the TOF of 117.69 mol(H2)center dot molRu-1 center dot min-1, whereas Ru/c is only 57.08 mol(H2)center dot molRu-1 center dot min-1. In addition, the TOF of co-Ru/c reaches to 436.51 mol(H2)center dot molRu-1 center dot min-1 (96.7 L(H2)center dot gRu-1 center dot min-1) in the presence of NaOH. (c) 2021 Hydrogen Energy Publications LLc. Published by Elsevier Ltd. All rights reserved.

关键词： Sodium borohydride Hydrogen co-Ru c Bimetallic Hydrolysis

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Photoreactive polymer and c,H-insertion reaction to tailor the properties of cHA/gelatin-based scaffold

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INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND cHARAcTERIZATION 2022年第5期27卷 326-345页

作者： Ardhani, Retno Suraya, Tiyastiti Wulanjati, Martha Purnami Ana, Ika Dewi Ruehe, Jurgen Pidhatika, Bidhari Univ Gadjah Mada Fac Dent Dept Dent Biomed Sci Yogyakarta Indonesia Minist Ind Ctr Standardizat & Ind Serv Leather Rubber & Plas Jl Sokonandi 9 Yogyakarta Indonesia Natl Res & Innovat Agcy Republ Indonesia PRTPP BR Res Ctr Food Technol & Proc Yogyakarta Indonesia Univ Freiburg Freiburg Inst Interact Mat & Bioinspired Technol Dept Microsyst Engn IMTEK DFG Cluster Excellence LivMatS Freiburg Germany Natl Res & Innovat Agcy Republ Indonesia BRIN Jakarta Indonesia

A series of photoreactive polymers containing poly(N,N-dimethylacrylamide) and 2-hydroxy-(4-methacryloyloxybenzophenone), P(DMAA-n%MABP-OH), was explored to modify sheet-formed carbonated hydroxyapatite/gelatin (cHA/gelatin) scaffold. Under UV-light illumination, the benzophenones react with any c-H bonds in their vicinity through a c,H-insertion mechanism, enabling PDMAA-based hydrogel formation that is covalently attached to the gelatin. NMR spectroscopy confirmed the chemical structure of P(DMAA-n%MABP-OH) polymers with aimed n = 1, 5, 10, while GPc determined their molecular masses. The benzophenone reactivity under UV-light illumination for 0-240 min. was demonstrated using UV-Vis spectroscopy at 240-400 nm. After immobilization of P(DMAA-n%MABP-OH) onto the cHA/gelatin scaffold, typical FTIR vibration bands of both compounds could be detected on the spectra of the modified scaffolds. SEM images showed that the scaffold is highly porous with approximately 100 mu m thickness. P(DMAA-n%MABP-OH) addition led to 2-3 times increase in thickness and 15-19% mass addition. Furthermore, it was shown that chemical (degradation and ca2+ release profile), physical (4-7 swelling index), mechanical (0.06-0.17 MPa wet tensile strength and 0.2-0.8 MPa elastic modulus), and biological (cell adhesion) properties of the scaffold could be tailored by varying the photocrosslinker content. cytotoxicity test showed that all studied cHA/gelatin-based scaffolds were nontoxic (>80% cell viability).

关键词： c H-insertion crosslinking hydrogel photoreactive polymer scaffold

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Determinations of combustion and formation enthalpies of c_(60)and c_(70)

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Science china chemistry 1998年第5期41卷 543-548页

作者：安绪武陈斌何俊 1. Institute of Chemistry Chinese Academy of Sciences 100080 Beijing China

By using a micro\|bomb calorimeter, the standard enthalpies of combustion of c 60 and c 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion of c 60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of c 60 and c 70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close.

关键词： c 60 c 70 enthalpy of combustion enthalpy of formation molecular strain energy.

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Storage of c, N, and P affected by afforestation with Salix cupularis in an alpine semiarid desert ecosystem

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LAND DEGRADATION & DEVELOPMENT 2018年第1期29卷 188-198页

作者： Hu, Yu-Fu Shu, Xiang-Yang He, Jia Zhang, Yu-Lin Xiao, Hai-Hua Tang, Xiao-Yan Gu, Yun-Fu Lan, Ting Xia, Jian-Guo Ling, Jing chen, Guang-Deng Wang, chang-Quan Deng, Liang-Ji Yuan, Shu Sichuan Agr Univ Coll Resources Chengdu 611130 Sichuan Peoples R China Harbin Inst Technol Shenzhen Shenzhen Key Lab Organ Pollut Prevent & Control Shenzhen 518055 Peoples R China

Few systemic assessments have evaluated the success of these afforestation programs in alpine semiarid desert ecosystems in the Qinghai-Tibet Plateau. In this study, we investigated the influences of three Salix cupularis plantation age classes (6, 18, and 34years) on the carbon (c), nitrogen (N), and phosphorus (P) storages and stoichiometry of the soil-plant ecosystem. The consequences of *** plantation induced soil spatial heterogeneity. The soil-plant ecosystem c storage increased after the plantation. The N storage showed an increasing trend from 6 to 18years and then slightly decreased. The P storage presented a continuously declining trend. The result indicated that the imbalance in soil N, P, c occurred with plantation age because of the imbalance of their inputs. The N and P uptakes from subsoil and redistribution to topsoil by *** may contribute to meet N and P demands for the understory plants. Leaf N:P ratios varied from 8.3 to 17.5. These results imply that N and P status are the main factors limiting plant growth in the alpine-cold desert ecosystem. Thus, we recommend adding N and P fertilizers during plant growth.

关键词： afforestation alpine semiarid desert soil-plant system stoichiometry c N and P storage salix plantations

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Effect of off-axis angle on mesoscale deformation and failure behavior of plain-woven c/Sic composites with digital image correlation

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2022年第12期42卷 4712-4722页

作者： Teng, Xuefeng Lyu, Shuangqi Hu, Xiaoan Jiang, Yun Nie, Xiangfan Liu, Xin Li, Longbiao Nanchang Hangkong Univ Sch Aircraft Engn Nanchang 330063 Peoples R China Jiangxi Key Lab Micro Aeroengine Nanchang 330063 Peoples R China Civil Aviat Flight Univ China Aviat Engn Coll Guanghan 618307 Sichuan Peoples R China Nanchang Hangkong Univ Anal & Testing Ctr Nanchang 330063 Peoples R China AF Engn Univ Sci & Technol Plasma Dynam Lab Xi'an 710038 Shaanxi Peoples R China China Acad Launch Vehicle Technol Beijing 100076 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Civil Aviat Nanjing 210016 Peoples R China

In this study, the deformation response and failure behavior of a plain-woven c/Sic composite were investigated under on-axis and off-axis tensile loading. Digital image correlation (DIc) was utilized to characterize the full field deformation and mesoscale strain distribution. The test results indicate a strong influence of the woven architecture on the mechanical properties and strain distribution, and the materials exhibit failure modes dependent on the loading directions or off-axis angles: the fracture positions of different layers are the same under off-axial load, while for on-axil loading, the fracture positions of different layers do not affect each other. SEM results provide direct evidence that the width of the off-axis specimen has a great influence on the mechanical properties. The reduction of the modulus and strength of off-axis specimen, is not only due to the off axis loading, but also due to the reduction of effective bearing area or effective bearing fiber.

关键词： Plain-woven c Sic composites Digital image correlation Off-axis Failure behavior

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A Progressive Oxidative Damage Model of c/Sic composites under Stressed Oxidation Environments

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APPLIED cOMPOSITE MATERIALS 2021年第5期28卷 1609-1629页

作者： Ding, Junjie Sun, Zhigang chen, Xihui Niu, Xuming Jin, Yu Song, Yingdong Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Energy & Power Engn Jiangsu Prov Key Lab Aerosp Power Syst Nanjing 210016 Peoples R China Minist Ind & Informat Technol Key Lab Aeroengine Thermal Environm & Struct Nanjing 210016 Peoples R China

A progressive oxidative damage model of c/Sic composites, which is based on the oxidation mechanism and mechanical model of c/Sic composites, is presented to simulate the damage process of c/Sic composite under stressed oxidation environments. Firstly, the oxidation failure time of fibers was calculated according to the fiber stress and the fiber strength decline rule under stressed oxidation environments. Secondly, the stress redistribution and crack propagation around fracture fibers were given by combining the fracture position of fibers with the mechanical model, and the crack propagation would cause more fibers to be oxidized. Thirdly, the progressive oxidative damage process of c/Sic composites under stressed oxidation environments was simulated by repeating the cyclic process of fiber oxidation fracture and crack propagation around the fracture fibers. Finally, through the progressive oxidative damage model, the stress-strain curves and fracture morphology of the unidirectional c/Sic composites after stressed oxidation were predicted. The simulation results were correlated well with the experimental results, in terms of stressed oxidation life, stress-strain curve and variation law of fracture morphology, which indicated the reliability of the model.

关键词： Progressive oxidative damage model c Sic composites Stressed oxidation environments Oxidation fracture crack propagation Stress-strain curve

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High temperature flexural strength, microstructure, phase evolution and anti-oxidation mechanism of Al-coated carbon fiber/boron phenolic resin ceramizable composite modified with TiB2 and B4c

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cERAMIcS INTERNATIONAL 2023年第15期49卷 25003-25015页

作者： Deng, Zongyi Yang, Xueyuan Yu, Xiaobo Huang, Zhixiong Zhu, Di Shi, Minxian Wuhan Univ Technol Key Lab Adv Technol Specially Funct Mat Minist Educ Wuhan 430070 Peoples R China Hubei Longzhong Lab Xiangyang 441000 Peoples R China China Aerosp Sci & Technol Corp Hubei Inst Aerosp Chem Technol Xiangyang 441000 Peoples R China

carbon fiber/phenolic resin composites (cF/Ph) have attracted great interests in the field of thermal protection materials for their characteristics of high specific strength and easy manufacturing. However, cF/Ph are inherently susceptible to oxidation failure at elevated temperatures. In this study, a novel Al-coated carbon fiber/ boron phenolic resin ceramizable composite modified with TiB2 and B4c was fabricated by an impregnating and compression molding route. Thermal stability, flexural strength, microstructure and phase evolution of the resulting ceramizable composite were studied. The residue yield at 1400 degrees c and flexural strength after treated at 1400 degrees c for 15min was 90.4% and 53.1 MPa, respectively, which was increased by 15.9% and 532.1% than that without ceramizable fillers. Surface defects generated by matrix pyrolysis were well healed, and Pyc and carbon fibers were covered with dense ceramic layers while the fracture surface was covered with relatively continuous ceramic layers without visible pores. Multiphase ceramics composed of TiB2, TiO2, Tic and Pyc were identified. Furthermore, oxidation failure and anti-oxidation mechanism was revealed based on the aforementioned characterizations and thermodynamic calculation results. Oxidation resistance got enhanced markedly for synergistic effects of oxygen consuming, carbon fixation, oxygen barrier and endothermic effect, which were derived from ceramization reactions between TiB2, B4c, O2, Al and Pyc.

关键词： ceramizable composite B Failure analysis c corrosion Mechanical properties E Thermal applications

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