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Enhanced hydrogen evolution performance by 3D ordered macroporous Ru-CoP@NC electrocatalysts

Rare Metals 2024年第3期43卷 1095-1107页

作者： Chen-Chen Zhang Sheng Wei Li-Xian Sun Yi-Fang Ouyang fen xu Hai-Liang Chu Hong-GePan Li-Xin Chen xue-Zhang Xiao School of Material Science and Engineering Guilin University of Electronic TechnologyGuilin541004China School of Chemistry and Chemical Engineering Guangxi UniversityNanning530004China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen518055GuangdongChina Institute of Science and Technology for New Energy Xi'an Technological UniversityXi'an710021China School of Materials Science and Engineering Zhejiang UniversityHangzhou310058China

Electrocatalytic water splitting coupled with sustainable energies is identified as an environmentally friendly and renewable strategy to generate high-quality hydrogen for the fuel cells.However,the main challenge is to develop high performance,low cost and chemically stable electrocatalysts to decline the energy barriers and enhance the sluggish kinetics of hydrogen evolution reaction(HER).Herein,a three-dimensional hierarchically ordered macroporous Ru-CoP@NC electrocatalyst(3DOM Ru-CoP@NC)derived from ordered macro-microporous metal-organic frameworks has been prepared using the precursor@template and double-solvent methods.The prepared 3DOM Ru-CoP@NC catalyst exhibits an overpotential of 15 mV(j=10 mA·cm^(-2))and a reaction Tafel slope of 38 mV·dec^(-1)in alkaline electrolyte,which are superior to commercial Pt@C catalyst.Additionally,the overpotential and reaction Tafel slope of this catalyst in acidic media are 45 mV and 50 mV·dec^(-1),respectively.The outstanding HER activities of 3DOM Ru-CoP@NC catalysts are ascribed to the 3D highly interconnectedreticular nanospaces that can increase effective reaction active sites.The N dope d carbon framework improves the electronic properties and conductivity.Moreover,the strong interaction of Ru and CoP nanoparticles also boosts the HER process.These results indicate that 3DOM Ru-CoP@NC catalysts with high catalytic activities have a broad application prospect in the future.

关键词： Hydrogen evolution reaction Template method 3D ordered macroporous Ru-CoP@NC

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Modulated noble metal/2D MOF heterostructures for improved hydrogen storage of MgH2

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Rare Metals 2024年第4期43卷 1672-1685页

作者： Zeng-Yi Li Li-Xian Sun fen xu Yu-Mei Luo Yong-Peng Xia Sheng Wei Chen-Chen Zhang Ri-Guang Cheng Chao-feng Ye Meng-Yuan Liu Ju-Lan Zeng Zhong Cao Hong-Ge Pan School of Material Science and Engineering Guilin University of Electronic Technology School of Chemistry and Chemical Engineering Changsha University of Science and Technology Institute of Science and Technology for New Energy Xi'an Technological University

The conjugation of external species with twodimensional（2D） materials has broad application prospects.In this study,we have explored the potential of noble metal/2D MOF heterostructures in hydrogen storage.Specifically,the MgH2-Ni-MOF@Pd system has shown remarkable hydrogen desorption/sorption performances,starting to liberate hydrogen at 181 0C,which is 230 0C lower than that of pristine MgH2.Under the catalytic effect of Ni-MOF@Pd,the dehydrogenation apparent activation energy of MgH2 is noticeably decreased from（133.5 ± 17.5） to（34.58 ± 1.87） kJ·mol-1,and the hydrogenation apparent activation energy is reduced from（70.41 ± 7.43） to（25.78 ± 4.64） kJ·mol-1,which is lowered by 63.4%.The fully-dehydrogenated MgH2-NiMOF@Pd composite rapidly uptakes hydrogen,with 2.62wt% at 100℃ and 6.06 wt% at 150℃ within 300 s,respectively.The mechanism analysis of MgH2 catalyzed by Ni-MOF@Pd has revealed that the transformation of Mg2Ni and Mg2NiH4could act as a "hydrogen pump",providing numerous channels for fast diffusion and transport of hydrogen atoms.Moreover,in the dehydrogenation process,the element Pd reacts with MgH2to form the MgPd alloy phase,which makes MgH2take precedence to decompose through the Mg-Pd alloy rather than self-decomposition,further reducing thermal stability and improving de/hydrogenation kinetics.The synergistic effect of Mg-Pd,Mg2Ni,and the special ultra-thin 2D sheet structure of the additive is the main reason for the good hydrogen storage property of MgH2-Ni-MOF@Pd.Our findings provide inspiration for designing efficient multifunctional additives with unique morphologies to optimize the hydrogen desorption/sorption behaviors of hydrogen storage materials.

关键词： Hydrogen storage Magnesium hydride 2D metal-organic framework nanosheets Ni/Pd Synergistic catalysis

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Understanding the dehydrogenation properties of Mg(0001)/MgH_(2)(110)interface from first principles

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Materials Reports(Energy) 2024年第1期4卷 89-94页

作者： Jianchuan Wang Bo Han Zhiquan Zeng Shiyi Wen fen xu Yong Du State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083PR China Powder Metallurgy Research Institute Central South UniversityChangsha410083PR China Guangxi Key Laboratory of Information Materials Guilin University of Electronic TechnologyGuilin541004PR China

Magnesium hydride is one of the most promising solid-state hydrogen storage materials for on-board application.Hydrogen desorption from MgH_(2) is accompanied by the formation of the Mg/MgH_(2) interfaces,which may play a key role in the further dehydrogenation process.In this work,first-principles calculations have been used to understand the dehydrogenation properties of the Mg(0001)/MgH_(2)(110) interface.It is found that the Mg(0001)/MgH_(2)(110) interface can weaken the Mg-H bond.The removal energies for hydrogen atoms in the interface zone are significantly lower compared to those of bulk MgH_(2).In terms of H mobility,hydrogen diffusion within the interface as well as into the Mg matrix is considered.The calculated energy barriers reveal that the migration of hydrogen atoms in the interface zone is easier than that in the bulk MgH_(2).Based on the hydrogen removal energies and diffusion barriers,we conclude that the formation of the Mg(0001)/MgH_(2)(110) interface facilitates the dehydrogenation process of magnesium hydride.

关键词： Magnesium hydrides First-principles calculation Hydrogen storage materials Interface Hydrogen desorption

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Fault Estimation for a Class of Markov Jump Piecewise-Affine Systems: Current Feedback Based Iterative Learning Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 418-429页

作者： Yanzheng Zhu Nuo xu fen Wu Xinkai Chen Donghua Zhou IEEE College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China College of Mechanical Engineering and Automation Huaqiao UniversityXiamen 361021China Department of Mechanical and Aerospace Engineering North Carolina State UniversityRaleigh NC 27695 USA Department of Electronic and Information Systems Shibaura Institute of TechnologySaitama 337-8570Japan

In this paper, the issues of stochastic stability analysis and fault estimation are investigated for a class of continuoustime Markov jump piecewise-affine(PWA) systems against actuator and sensor faults. Firstly, a novel mode-dependent PWA iterative learning observer with current feedback is designed to estimate the system states and faults, simultaneously, which contains both the previous iteration information and the current feedback mechanism. The auxiliary feedback channel optimizes the response speed of the observer, therefore the estimation error would converge to zero rapidly. Then, sufficient conditions for stochastic stability with guaranteed performance are demonstrated for the estimation error system, and the equivalence relations between the system information and the estimated information can be established via iterative accumulating representation.Finally, two illustrative examples containing a class of tunnel diode circuit systems are presented to fully demonstrate the effectiveness and superiority of the proposed iterative learning observer with current feedback.

关键词： Current feedback fault estimation iterative learning observer Markov jump piecewise-affine system

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Alkyl dimethyl betaine activates the low-temperature collection capacity of sodium oleate for scheelite

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 71-80页

作者： xu Wang Zhengquan Zhang Yanfang Cui Wei Li Congren Yang Hao Song Wenqing Qin fen Jiao School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources Central South UniversityChangsha 410083China College of Engineering Drexel UniversityPhiladelphiaPA 19102USA Luoyang Zhenbei Industry and Trade Co. Ltd.Luoyang 47100China

The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB and NaOl was explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test, and flotation reagent size measurement.The flotation tests revealed that the collector mixed with octadecyl dimethyl betaine (ODB) and NaOl in a mass ratio of 4:96 exhibited the highest collection capacity. The combined collector could increase the scheelite recovery by 3.48% at low temperatures of 8–12℃. This is particularly relevant in the Luanchuan area, which has the largest scheelite concentrate output in China. The results confirmed that ODB enhanced the collection capability of NaOl by improving the dispersion and foaming performance. Betaine can be introduced as an additive to NaOl to improve the recovery of scheelite at low temperatures.

关键词： scheelite betaine low temperature synergistic effect dispersion foamability

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Manipulating the Phase Transition Behavior of Dual Temperature-Responsive Block Copolymers by Adjusting Composition and Sequence

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Chinese Journal of Polymer Science 2024年第2期42卷 176-187,I0006页

作者： Zhi Zou Xiang xu Hai-Tao Zhao Jian-Nan Cheng Wei-Wei He Li-fen Zhang Zhen-Ping Cheng Suzhou key Laboratory of Macromolecular Design and Precision Synthesis Jiangsu Key Laboratory of Advanced Functional Polymer Design and ApplicationState and Local Joint Engineering Laboratory for Novel Functional Polymeric MaterialsCollege of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou215123China State Key Laboratory of Radiation Medicine and Protection School for Radiological and Interdisciplinary Sciences(RAD-X)and Collaborative Innovation Center of Radiation Medicine of JiangsuSoochow UniversitySuzhou215123China

Temperature-responsive polymers have garnered significant attention due to their ability to respond to external stimuli.In this work,dual temperature-responsive block copolymers are synthesized via reversible addition-fragmentation chain transfer polymerization(RAFT)polymerization utilizing zwitterionic monomer methacryloyl ethyl sulfobetaine(SBMA) and N-isopropyl acrylamide(NIPAAm) as monomers.The thermal responsive behaviors can be easily modulated by incorporating additional hydrophobic monomer benzyl acrylate(BN) or hydrophilic monomer acrylic acid(AA),adjusting concentration or pH,or varying the degree of polymerization of the block chain segments.The cloud points of the copolymers are determined by UV-Vis spectrophotometry,and these copolymers exhibit both controlled upper and lower critical solu bility temperatures(LCST and UCST) in aqueous solution.This study analyzes and summarizes the influencing factors of dual temperature responsive block copolymers by exploring the effects of various conditions on the phase transition temperature of temperature-sensitive polymers to explore the relationship between their properties and environment and structure to make them more selective in terms of temperature application range and regulation laws.It is very interesting that the introduction of poly-acrylic acid(PAA) segments in the middle of di-block copolymer PSBMA_(55)-b-PNIPAAm_(80) to form PSBMA_(55)-b-PAA_(x)-b-PNIPAAm_(80) results in a reversal of temperature-responsive behaviors from 'U'(LCST UCST) type,while the copolymer PSBMA_(55)-b-P(NIPAAm_(80)-co-AA_(x)) not.This work provides a clue for tuning the phase transition behavior of polymers for manufacture of extreme smart materials.

关键词： Temperature responsive polymers High critical solubility temperature(UCST) Low critical solubility temperature(LCST) Block copolymers

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Drastic change in dynamics as Typhoon Lekima experiences an eyewall replacement cycle

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Frontiers of Earth Science 2022年第1期16卷 121-131页

作者： fen xu X.San LIANG School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China. School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China

Why does the 1909 typhoon,Lekima,become so destructive after making landfall in China?Using a newly developed mathematical apparatus,the multiscale window transform(MWT),and the MWT-based localized mutliscale energetics analysis and theory of canonical transfer,this study is intended to give a partial answer from a dynamical point of view.The ECMWF reanalysis fields are first reconstructed onto the background window,the TC-scale window,and the convection-scale window.A localized energetics analysis is then performed,which reveals to us distinctly different scenarios before and after August 8–9,2019,when an eyewall replacement cycle takes place.Before that,the energy supply in the upper layer is mainly via a strong upper layer-limited baroclinic instability;the available potential energy thus-gained is then converted into the TC-scale kinetic energy,with a portion to fuel Lekima’s upper part,another portion carried downward via pressure work flux to maintain the cyclone’s lower part.After the eyewall replacement cycle,a drastic change in dynamics occurs.First,the pressure work is greatly increased in magnitude.A positive baroclinic transfer almost spreads throughout the troposphere,and so does barotropic transfer;in other words,the whole air column is now both barotropically and baroclinically unstable.These newly occurred instabilities help compensate the increasing consumption of the TC-scale kinetic energy,and hence help counteract the dissipation of Lekima after making landfalls.

关键词： Typhoon Lekima multiscale window transform canonical transfer multiscale energetics barotropic/baroclinic instability

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Synergistic effects of dodecane-castor oil acid mixture on the flotation responses of low-rank coal:A combined simulation and experimental study

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International Journal of Mining Science and Technology 2023年第5期33卷 649-658页

作者： fen xu Shiwei Wang Rongjie Kong Chengyong Wang College of Environmental and Chemical Engineering Dalian UniversityDalian 116622China School of Mines and Mechanical Engineering Liupanshui Normal UniversityLiupanshui 553004China

The utilization of an appropriate collector or surfactant is crucial for the beneficiation of low-rank coal.However,in previous studies,the selection of surfactants was primarily based on flotation procedures,which hinders the understanding of the interaction mechanism between surfactant groups and oxygen-containing functional groups at the surface of low-rank coal.In this study,we investigate the flotation of low-rank coal in the presence of a composite collector by using a combined theoretical and experimental approach.The maximum flotation mass recovery achieved was 82.89%using a 3:1 mixture of dodecane and castor oil acid.Fourier-transform infrared and X-ray photoelectron spectroscopic analyses showed that castor oil acid was effectively adsorbed onto the surface of low-rank coal,enhancing the hydrophobicity of the coal.In addition,the diffusion coefficient of water molecules in the water-composite collector-coal system was greater than that in the dodecane system.Moreover,due to the presence of castor oil acid in the flotation process,the adsorption distance of dodecane and low-rank coal became shorter.Molecular dynamics simulations revealed that the diffusion and interaction of surfactant molecules at the interface of low-rank coal particles and water was enhanced because the adsorption of the dodecane-castor oil acid mixture is primarily controlled by hydrogen bonds and electrostatic attraction.Based on these results,a better surfactant for flotation of low-rank coal is also proposed.

关键词： Low-rank coal Flotation Castor oil acid Surface hydrophobicity Molecular dynamics simulation

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Therapeutic Effectiveness of Leukocyte-and Platelet-rich Fibrin for Diabetic Foot Ulcers:A Retrospective Study

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Current Medical Science 2024年第3期44卷 568-577页

作者： fen WANG Xiao-ling ZHANG Jing ZHANG Song GONG Jing TAO Hui XIANG Xiao-qing FU xu-na BIAN xue-feng YU An-hui xu Cheng-la YI Shi-ying SHAO Department of Endocrinology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China Branch of National Clinical Research Center for Metabolic Diseases Wuhan430030China Department of Radiology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China Department of Trauma Surgery Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030China

Objective Diabetic foot ulcer(DFU)is one of the most serious complications of diabetes.Leukocyte-and platelet-rich fibrin(L-PRF)is a second-generation autologous platelet-rich plasma.This study aims to investigate the clinical effects of L-PRF in patients with diabetes in real clinical practice.Methods Patients with DFU who received L-PRF treatment and standard of care(SOC)from 2018 to 2019 in Tongji Hospital were enrolled.The clinical information including patient characteristics,wound evaluation(area,severity,infection,blood supply),SOC of DFU,and images of ulcers was retrospectively extracted and analyzed.L-PRF treatment was performed every 7±2 days until the ulcer exhibited complete epithelialization or an overall percent volume reduction(PVR)greater than 80%.Therapeutic effectiveness,including overall PVR and the overall and weekly healing rates,was evaluated.Results Totally,26 patients with DFU were enrolled,and they had an ulcer duration of 47.0(35.0,72.3)days.The severity and infection of ulcers varied,as indicated by the Site,Ischemia,Neuropathy,Bacterial Infection,and Depth(SINBAD)scores of 2–6,Wagner grades of 1–4,and the Perfusion,Extent,Depth,Infection and Sensation(PEDIS)scores of 2–4.The initial ulcer volume before L-PRF treatment was 4.94(1.50,13.83)cm3,and the final ulcer volume was 0.35(0.03,1.76)cm3.The median number of L-PRF doses was 3(2,5).A total of 11 patients achieved complete epithelialization after the fifth week of treatment,and 19 patients achieved at least an 80%volume reduction after the seventh week.The overall wound-healing rate was 1.47(0.63,3.29)cm3/week,and the healing rate was faster in the first 2 weeks than in the remaining weeks.Concurrent treatment did not change the percentage of complete epithelialization or healing rate.Conclusion Adding L-PRF to SOC significantly improved wound healing in patients with DFU independent of the ankle brachial index,SINBAD score,or Wagner grade,indicating that this method is appropriate for DFU treatment under different clinical conditions

关键词： diabetic foot ulcer autologous platelet-rich plasma leukocyte-and platelet-rich fibrin standard of care percentage volume reduction

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Geometric regulation of collective cell tangential ordering migration

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Journal of Innovative Optical Health Sciences 2024年第2期17卷 94-103页

作者： Hao Dong Yuming Zhou xuehe Ma Junfang Liu Fulin Xing Jianyu Yang Qiushuo Sun Qingsong Hu fen Hu Leiting Pan Jingjun xu The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry School of Physics and TEDA Institute of Applied Physics Nankai University Tianjin 300071 P.R.China State Key Laboratory of Medicinal Chemical Biology Frontiers Science Center for Cell Responses College of Life Sciences Nankai University Tianjin 300071 P.R.China Shenzhen Research Institute of Nankai Uniwersity Shenzhen Guangdong 518083P.R.China Collaborative Innovation Center of Extreme Optics Shanxi University.Taiyuan Shanxi 030006P.R.China

Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rotation of epithelial cells confined in circular substrates.Here,we aim to explore how geometric shapes of confinement regulate this collective cell movement.We develop quantitative methods for cell velocity orientation analysis,and find that boundary cells exhibit stronger tangential ordering migration than inner cells in circular pattern.Furthermore,decreased tangential ordering movement capability of collective cells in triangular and square patterns are observed,due to the disturbance of cell motion at unsmooth corners of these patterns.On the other hand,the collective cell rotation is slightly affected by a convex defect of the circular pattern,while almost hindered with a concave defect,also resulting from different smoothness features of their boundaries.Numerical simulations employing cell Potts model well reproduce and extend experimental observations.Together,our results highlight the importance of boundary smoothness in the regulation of collective cell tangential ordering migration.

关键词： Collective cell migration spatial restrictions tangential ordering geometric regula-tion cell Potts model

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