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The degradation of cathodic Fe/N/C catalyst in PEMFCs:The evolution of remanent active sites after demetallation

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Journal of Materials Science & Technology 2024年第6期173卷 100-106页

作者： Xiaohua yang Wentao Sun Jiatang Chen yang Gao Rongxian zhang Qun Luo Tao lyu Lei Du Institut National de la Recherche Scientifique-Énergie Matériaux et Télécommunications J3X 1P7 VarennesQCCanada School of Chemistry and Chemical Engineering Jiangsu UniversityZhenjiang 212013China State Key Laboratory of Advanced Special Steels&Shanghai Key Laboratory of Advanced Ferrometallurgy School of Materials Science and EngineeringShanghai UniversityShanghai 200444China Huangpu Hydrogen Energy Innovation Center School of Chemistry and Chemical EngineeringGuangzhou UniversityGuangzhou 510006China

The state-of-the-art Fe/N/C catalyst has presented comparable initial cathode performance to the benchmark Pt/C catalyst in proton exchange membrane fuel cells(PEMFCs).However,the major bottleneck is its significant activity decay in real-world PEMFC *** superposed“fast decay”and“slow decay”have been well documented to describe the degradation process of Fe/N/C catalysts during PEMFC *** fast decay has been well understood in close relation to the demetallation at the initial 15-h stability ***,it is still unclear how the remanent active sites evolve after *** this end,the catalyst performance and evolution of a typical Fe/N/C active site were herein investigated through postmortem characterizations of the membrane electrode assemblies(MEAs)after different *** is presented that 1 bar pressure and 80℃ temperature are the optimized conditions for Fe/N/C ***,the“fast decay”in the initial 15 h is immune to the various operating parameters,while the“slow decay”highly depends on the applied temperature and *** to the X-ray absorption spectra(XAS)analysis and stability test of MEA,the gradual evolution of Fe-N coordination to Fe-O is found correlated with the“slow decay”and accounts for the catalyst decay after the demetallation process.

关键词： Fe/N/C Stability Decay mechanism Metal oxidation PEMFCs

The structure-directing role of heterologous seeds in the synthesis of zeolite

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Green Energy & Environment 2024年第5期9卷 792-801页

作者： Haoyang zhang Binyu Wang Wenfu yan State Key Laboratory of Inorganic Synthesis&Preparative Chemistry College of ChemistryJilin UniversityChangchun130012China

Zeolites have been widely used as catalysts,ion-exchangers,and adsorbents in chemical industries,detergent industry,steel industry,glass industry,ceramic industry,medical and healthﬁeld,and environmentalﬁeld,and recently applied in energy ***-assisted synthesis is a very effective approach in promoting the crystallization of *** some cases,the target zeolite cannot be formed in the absence of seed *** homologous seed-assisted synthesis,the structure of the seed zeolite is the same to that of the target zeolite,while the structure of the seed zeolite is different to that of the target zeolite in the heterologous seed-assisted *** this review,we brieﬂy summarized the heterologous seed-assisted syntheses of zeolites and analyzed the structure-directing effect of heterologous seeds and surveyed the“common composite building units(CBUs)hypothesis”and the“common secondary building units(SBUs)hypothesis”.However,both hypotheses cannot explain all observations on the heterologous seed-assisted ***,we proposed that the formation of the target zeolite does need nuclei with the structure of target zeolite and the formation of the nuclei of the target zeolite can be promoted by either the undissolved seed crystals with the same CBUs or SBUs to the target zeolite or by the facilitated appropriate distribution of the speciﬁc building units due to the presence of the heterologous seed that does not have any common CBUs and SBUs with the target zeolite.

关键词： Zeolite Heterologous seed Synthesis Structure-directing effect

Glacial-interglacial cycles recorded in clay minerals from the eastern Tibetan Plateau over the last 800 ka and their indications

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Science China Earth Sciences 2024年第7期67卷 2162-2177页

作者： Xiaoyan zhang Chunxia zhang yan ZHAO Bin HU Zhengtang GUO Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Clay mineral proxies have been widely used to reconstruct changes in provenance and the ***,high-altitude clay mineral indications and long-term and orbital variations have not been fully ***,we present an800-ka clay-mineral record from a lacustrine sediment core(ZB13-C2)from the Zoige Basin on the eastern Tibetan Plateau(TP).X-ray diffraction and scanning electron microscopy were used to identify the clay mineral assemblages and their micromorphological characteristics of core *** results revealed that the clay minerals in core ZB13-C2 are mainly illite,with small amounts of chlorite,kaolinite,and smectite(including irregular mixed-layers of illite-smectite(I/S)and chloritesmectite(C/S)).The clay mineral assemblages and proxies exhibit three stages of change,which are mainly controlled by the Zoige watershed range under different climate *** watershed was limited to the southeastern region with altitudes ranging from~3500 to~4200 meters above sea level(m a.s.l.),and glacial-interglacial hydraulic erosion controlled the input of bedrock debris during 800-621 ka *** expanded to higher altitudes(~4200 to~4700 m a.s.l.)due to stronger seasonal freezethaw weathering without significant glacial-interglacial variations under a cooling and drying climate during 621-100 ka ***,it expanded to its highest altitudes of~4700 to~5200 m *** of the watershed after 100 ka BP,and hydraulic erosion increased obviously under a warm climate of the interstadial MIS 3 on the *** watershed underwent two major expansions under different climatic conditions at~621 ka and 100 ka BP,with the wet/dry alternation became strong at~621 ka *** results reveal that long-term temperature changes and the wet/dry alternation at high altitudes controlled the watershed range and degree of the physical erosion,and that the indications of clay minerals should be carefully clarified before they are used as climate indicators,especi

关键词： Quaternary Zoige Basin Lacustrine sediments Paleoenvironment Weathering

Multi-blade rubbing characteristics of the shaft-disk-blade-casing system with large rotation

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 111-136页

作者： Zhiyuan WU Linchuan ZHAO Han yan Ge yan Ao CHEN Wenming zhang State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Institute of Aerospace Systems Engineering Shanghai 201108China

Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.

关键词： shaft-disk-blade-casing(SDBC) large rotation spin and whirl multi-blade rubbing rotational effect

On the Shallowing of Antarctic Low-Level Temperature Inversions Projected by CESM-LE under RCP8.5

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Journal of Meteorological Research 2024年第3期38卷 586-599页

作者： Minghu DING Lin zhang Tingfeng DOU Yi HUANG Yingyan LUO Junmei lyu Cunde XIAO State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing100081China Key Laboratory of Meteorology and Ecological Environment of Hebei Province Hebei Provincial Institute of Meteorological SciencesShijiazhuang050021China College of Resources and Environment University of Chinese Academy of SciencesBeijing100049China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing100875China

Temperature inversions are frequently observed in the boundary layer and lower troposphere of polar *** variations of the low-level temperature inversions in these regions,especially the Antarctic,are still poorly *** to the scarcity of observations in the Antarctic,reanalysis data and numerical simulations are often used in the study of Antarctic climate *** on ERA-Interim,ERA5,JRA-55,and NCEP-NCAR reanalysis products,this study examines temporal and spatial variations of Antarctic inversion depth in austral autumn and winter during *** inversions are found to occur over the high plateau areas of the Antarctic *** on the Mann-Kendall test,ERA-Interim and ERA5 data reveal that the Antarctic inversion depth in austral autumn and winter increased during 1992-2007,roughly maintained afterwards,and then significantly decreased since around *** decrease trend is more obvious in the last two months of ***,JRA-55 better represents the spatial distribution of inversion depth,and ERA-Interim has better interannual *** Community Earth System Model Large Ensemble(CESM-LE)30-member simulations in 1979-2005 were first verified against JRA-55,showing reasonable consistency,and were then used to project the future changes of Antarctic low-level inversion depth over 2031-2050 under *** CESM-LE projection results reveal that the temperature inversion will shallow in the Antarctic at the end of the 21st century,and the decrease in depth in autumn will be more pronounced than that in *** particular,the temperature inversion will weaken over the ice-free ocean,while it will remain stable over the ice sheet,showing certain spatial heterogeneity and seasonal dependence on the underlying cryospheric surface *** addition,the decrease of inversion depth is found closely linked with the reduction in sea ice,suggesting the strong effect of global warming on the thermal structure change o

关键词： boundary layer temperature inversion Antarctic climate change Community Earth System Model Large Ensemble(CESM-LE)

The Chinese guideline for management of snakebites

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World Journal of Emergency Medicine 2024年第5期15卷 333-355页

作者： Rongde Lai Shijiao yan Shijun Wang Shuqing yang zhangren yan Pin Lan Yonggao Wang Qi Li Jinlong Wang Wei Wang Yuefeng Ma Zijing Liang Jianfeng zhang Ning Zhou Xiaotong Han Xinchao zhang Mao zhang Xiaodong Zhao Guoqiang zhang Huadong Zhu Xuezhong Yu Chuanzhu lyu Emergency Department the First Affi liated Hospital of Guangzhou Medical UniversityGuangzhou 510120China School of Public Health Hainan Medical UniversityHaikou 571199China Surgery Department of Traditional Chinese Medicine the Affi liated People’s Hospital of Fujian University of Traditional Chinese MedicineFuzhou 350004China Emergency Department Chongqing University Central Hospital/Chongqing Emergency Medical CenterChongqing 400014China Department of Surgery of Traditional Chinese Medicine Affi liated Hospital of Jiangxi University of Chinese MedicineNanchang 330006China Department of Emergency Medicine the Fifth Affi liated Hospital of Wenzhou Medical University/Lishui Central HospitalLishui Hospital of Zhejiang UniversityLishui 323000China General Surgery Department the First Affi liated Hospital of Zhejiang Chinese Medical UniversityHangzhou 310006China Emergency Department Shengli Clinical Medical College of Fujian Medical UniversityFuzhou 350001China Emergency Department Chongqing University Fuling HospitalChongqing UniversityChongqing 408000China Emergency Department the First Affi liated Hospital of Guangxi Medical UniversityNanning 530021China Emergency Department the Second Affi liated Hospital of Zhejiang University School of MedicineHangzhou 310009China Emergency Department Wuming Hospital of Guangxi Medical UniversityNanning 530021China Emergency Department Central People's Hospital of ZhanjiangZhanjiang 524037China Emergency Department Hunan Provincial People's HospitalChangsha 410005China Emergency Department National Geriatrics Center of Beijing HospitalBeijing 100020China Emergency Department the Fourth Medical Center of the PLA General HospitalBeijing 100048China Emergency Department China-Japan Friendship HospitalBeijing 100029China Emergency Department Peking Union Medical College HospitalBeiJing 100730China Emergency Department Sichuan Academy of Medical Sciences/Sichuan Provincial People's HospitalChengdu 610072China Research Unit of Island Emergency

In 2009,the World Health Organization included snakebite on the list of neglected tropical diseases,acknowledging it as a common occupational hazard for farmers,plantation workers,and others,causing tens of thousands of deaths and chronic physical disabilities every *** guideline aims to provide practical information to help clinical professionals evaluate and treat snakebite *** recommendations are based on clinical experience and clinical research *** guideline focuses on the following topics:snake venom,clinical manifestations,auxiliary examination,diagnosis,treatments,and prevention.

关键词： Snakebite Envenomation Management Prevention

Energy absorption behaviors of a novel buffer lander-leg with Yoshimura core

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Chinese Journal of Aeronautics 2024年第4期37卷 333-342页

作者： yan XU He HUANG Chao zhang Rongji FU School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical UniversityXi’an 710072China

In the current soft-landing system,the lander-leg and the buffer are two independent parts which may cause weight *** traditional mechanical buffers also have their own shortcomings such as small buffer stroke and being non-reusable.A Novel Buffer Lander-leg with Yoshimura core (NBLY) is proposed in this paper,inspired by the Buckling Restrained Brace(BRB).The design details of NBLY and parameter definitions of the core are *** finite element analysis modes have been employed to analyze the nonlinear mechanical behaviors of NBLY subjected to the cyclic *** with four different core styles of hexagon,octagon,dodecagon and hexadecagon are analyzed and *** restraining ratio and cumulative dissipation energy ratio have been obtained to evaluate the energy absorption *** results show that the origami pattern has significant influences on the deformation ductility,plastic energy absorbing and axial load transferring to the *** NBLY with octagon core has outstanding properties,especially the hysteretic energy dissipation and enhancement of compression *** interaction mechanism between the core and encasing member constrains the deformation extensions and contributes to the frictional energy dissipation of the *** paper provides a new conceptual design of buffer lander-leg for soft-landing *** can realize the reuse function as a buffer lander-leg with better loading-bearing and energy absorption behaviors.

关键词： Lander-leg structure Origami Energy absorption Cyclic loading Finite element analysis

E-MobileNeXt: face expression recognition model based on improved MobileNeXt

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Optoelectronics Letters 2024年第2期20卷 122-128页

作者： zhang Xiang yan Chunman School of Physics and Electronic Engineering Northwest Normal UniversityLanzhou 730070China1

In response to the high complexity and low accuracy of current facial expression recognition networks, this paper proposes an E-Mobile Ne Xt network for facial expression recognition. E-Mobile Ne Xt is built based on our proposed E-Sand Glass block. In addition, we also improve the overall performance of the network through Rep Conv and SGE attention mechanisms. The experimental results show that the network model improves the expression recognition accuracy by 6.5% and 7.15% in RAF-DB and CK+ datasets, respectively, while the parameter and floating-point operations decreased by 0.79 M and 4.2 M compared with Mobile Ne Xt.

关键词： facial mechanisms. network

Kinetic model of vibration screening for granular materials based on biological neural network

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Particuology 2024年第5期88卷 98-106页

作者： Zhan Zhao yan zhang Fang Qin Mingzhi Jin School of Agricultural Engineering Jiangsu UniversityZhenjiang212013China Shandong Academy of Agricultural Machinery Sciences Ji'nan250100China

The kinetic model is the theoretical basis for optimizing the structure and operation performance of vibration screening *** this paper,a biological neurodynamic equation and neural connections were established according to the motion and interaction properties of the material under vibration *** material feeding to the screen and the material passing through apertures were considered as excitatory and inhibitory inputs,respectively,and the generated stable neural activity landscape was used to describe the material distribution on the 2D screen *** dynamic process of material vibration screening was simulated using discrete element method(DEM).By comparing the similarity between the material distribution established using biological neural network(BNN)and that obtained using DEM simulation,the optimum coefficients of BNN model under a certain screening parameter were determined,that is,one relationship between the BNN model coefficients and the screening operation parameters was *** screening parameters were randomly selected,and the corresponding relationships were established as a ***,with straw/grain ratio,aperture diameter,inclination angle,vibration strength in normal and tangential directions as inputs,five independent adaptive neuro-fuzzy inference systems(ANFIS)were established to predict the optimum BNN model coefficients,*** training results indicated that ANFIS models had good stability and *** flexibility and adaptability of the proposed BNN method was demonstrated by modeling material distribution under complex feeding conditions such as multiple regions and non-uniform rate.

关键词： Kinetic model Material distribution Vibration screening Biological neural network DEM simulation Adaptive neuro-fuzzy inference systems