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Stable carbon isotope composition and intrinsic water use efficiency in plants along an altitudinal gradient on the eastern slope of Yulong Snow Mountain, China

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Ecological Processes 2024年第2期13卷 218-230页

作者： feng Jiang Tao Pu Zi-Jing Xue Yan-Wei ma Xiao-Yi Shi Fu-Xi Shi College of Geography and Environmental Sciences Zhejiang Normal University Yulong Snow Mountain Glacier and Environment Observation and Research Station/State Key Laboratory of Cryospheric Sciences Northwest Institute of Eco-Environment and ResourcesChinese Academy of Sciences Key Laboratory of National Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of Forestry Jiangxi Agricultural University

Background Stable carbon isotope composition(δ13Cp) can be used to estimate the changes in intrinsic water use efficiency（iWUE） in plants,which helps us to better understand plants' response strategies to climate *** study focused on the variations in δ13Cpand iWUE for the different life-form plants（i.e.,herbs,shrubs,and trees）along an altitudinal gradient（3300,3600,3900,4100,4300,and 4500 m） on the eastern slope of Yulong Snow Mountain,southeastern margin of the Qinghai-Tibet *** response mechanisms of δ13Cpand iWUE for different life-form plants to altitude were thoroughly analyzed in this mountain *** The δ13Cpvalues of plants on the eastern slopes of Yulong Snow Mountain ranged from-30.4‰to-26.55‰,with a mean of-28.02‰,indicating a dominance of *** δ13Cpand iWUE values varied among different life-form plants in the order of herbs> shrubs> trees,particularly in 3600,3900,and 4300 ***δ13Cpand iWUE values for herbs and shrubs increased with altitude and were mainly controlled by air *** two parameters for trees exhibited a trend of initial decrease followed by an increase with *** 3900 m,the δ13Cpand iWUE values decreased with altitude,influenced by soil ***,above 3900 m,the two parameters increased with altitude,mainly regulated by air *** addition,iWUE was positively correlated with leaf P content but negatively correlated with leaf N:P ratio,especially for herbs and trees,suggesting that P plays a key role in modulating iWUE in this *** The diffe rentiated responses of water availability for different life-form plants to a higher altitudinal gradient are regulated by air temperature,soil moisture,and leaf P content in the Yulong Snow *** results provide valuable insights into understanding the wate r-carbon relationships in high-altitude ecosystems.

关键词： Stable carbon isotope Water use efficiency Altitude Life form Yulong Snow Mountain

Gradient sparsification for efficient wireless federated learning with differential privacy

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Science China(Information Sciences) 2024年第4期67卷 272-288页

作者： Kang WEI Jun LI Chuan ma Ming DING feng SHU Haitao ZHAO Wen CHEN Hongbo ZHU School of Electronic and Optical Engineering Nanjing University of Science and Technology Zhejiang Lab Key Laboratory of Computer Network and Information Integration(Southeast University) Ministry of Education Data61 Commonwealth Scientific and Industrial Research Organisation School of Information and Communication Engineering Hainan University School of Communications and Information Engineering Nanjing University of Posts and Telecommunications School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University

Federated learning(FL) enables distributed clients to collaboratively train a machine learning model without sharing raw data with each other. However, it suffers from the leakage of private information from uploading models. In addition, as the model size grows, the training latency increases due to the limited transmission bandwidth and model performance degradation while using differential privacy(DP)protection. In this paper, we propose a gradient sparsification empowered FL framework with DP over wireless channels, to improve training efficiency without sacrificing convergence performance. Specifically, we first design a random sparsification algorithm to retain a fraction of the gradient elements in each client’s local model, thereby mitigating the performance degradation induced by DP and reducing the number of transmission parameters over wireless channels. Then, we analyze the convergence bound of the proposed algorithm, by modeling a non-convex FL problem. Next, we formulate a time-sequential stochastic optimization problem for minimizing the developed convergence bound, under the constraints of transmit power, the average transmitting delay, as well as the client’s DP requirement. Utilizing the Lyapunov drift-plus-penalty framework, we develop an analytical solution to the optimization problem. Extensive experiments have been implemented on three real-life datasets to demonstrate the effectiveness of our proposed algorithm. We show that our proposed algorithms can fully exploit the interworking between communication and computation to outperform the baselines, i.e., random scheduling, round robin, and delay-minimization algorithms.

关键词： federated learning differential privacy gradient sparsification Lyapunov drift convergence analysis

Insight into the capacity degradation and structural evolution of single-crystal Ni-rich cathodes

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Journal of Energy Chemistry 2024年第8期95卷 68-76,I0003页

作者： Xiaodong Zhang Jiao Lin Ersha Fan Qingrong Huang Su ma Renjie Chen feng Wu Li Li Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Advanced Technology Research Institute Beijing Institute of TechnologyJinan 250300ShandongChina Collaborative Innovation Center of Electric Vehicles in Beijing Beijing 100081China

Single-crystal Ni-rich cathodes are a promising candidate for high-energy lithium-ion batteries due to their higher structural and cycling stability than polycrystalline ***,the phase evolution and capacity degradation of these single-crystal cathodes during continuous lithation/delithation cycling remains *** the mapping relationship between the macroscopic electrochemical properties and the material physicochemical properties is ***,we investigate the correlation between the physical-chemical characteristics,phase transition,and capacity decay using capacity differential curve feature identification and in-situ X-ray spectroscopic *** systematically clarify the dominant mechanism of phase evolution in aging *** high cut-off voltages can mitigate the slow kinetic and electrochemical properties of single-crystal *** also find that second-order differential capacity discharge characteristic curves can be used to identify the crystal structure disorder of Ni-rich *** findings constitute a step forward in elucidating the correlation between the electrochemical extrinsic properties and the physicochemical intrinsic properties and provide new perspectives for failure analysis of layered electrode materials.

关键词： Single-crystal cathodes Capacity decay Phase transition Differential capacity analysis

MOF‐derived 1D/3D N‐doped porous carbon for spatially confined electrochemical CO2 reduction to adjustable syngas

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Carbon Energy 2024年第8期6卷 1-13页

作者： Wei Zhang Hui Li Daming feng Chenglin Wu Chenghua Sun Baohua Jia Xue Liu Tianyi ma Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced materials Institute of Clean Energy ChemistryCollege of ChemistryLiaoning UniversityShenyangLiaoningChina School of Science RMIT UniversityMelbourneVictoriaAustralia School of Pharmaceutical and Chemical Engineering Taizhou UniversityTaizhouZhejiangChina Department of Chemistry and Biotechnology Swinburne University of TechnologyHawthornVictoriaAustralia

Electrochemical reduction of CO_(2)to syngas(CO and H_(2))offers an efficient way to mitigate carbon emissions and store intermittent renewable energy in ***,the hierarchical one‐dimensional/three‐dimensional nitrogen‐doped porous carbon(1D/3D NPC)is prepared by carbonizing the composite of Zn‐MOF‐74 crystals in situ grown on a commercial melamine sponge(MS),for electrochemical CO_(2)reduction reaction(CO_(2)RR).The 1D/3D NPC exhibits a high CO/H_(2)ratio(5.06)and CO yield(31 mmol g^(−1)h^(−1))at−0.55 V,which are 13.7 times and 21.4 times those of 1D porous carbon(derived from Zn‐MOF‐74)and N‐doped carbon(carbonized by MS),*** is attributed to the unique spatial environment of 1D/3D NPC,which increases the adsorption capacity of CO_(2)and promotes electron transfer from the 3D N‐doped carbon framework to 1D carbon,improving the reaction kinetics of CO_(2)*** results and charge density difference plots indicate that the active site of CO_(2)RR is the positively charged carbon atom adjacent to graphitic N on 1D carbon and the active site of HER is the pyridinic N on 1D *** presence of pyridinic N and pyrrolic N reduces the number of electron transfer,decreasing the reaction kinetics and the activity of CO_(2)*** CO/H_(2)ratio is related to the distribution of N species and the specific surface area,which are determined by the degree of spatial confinement *** CO/H_(2)ratios can be regulated by adjusting the carbonization temperature to adjust the degree of spatial confinement *** the low cost of feedstock and easy strategy,1D/3D NPC catalysts have great potential for industrial application.

关键词： electrochemical CO_(2)reduction reaction melamine sponge metal‐organic frameworks porous carbon syngas

Micelle-directed self-assembly of single-crystal-like mesoporous stoichiometric oxides for high-performance lithium storage

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National Science Review 2024年第4期11卷 195-205页

作者： Yanhua Wan Changyao Wang Xingmiao Zhang Yang Yin Mengmeng Liu Bing ma Linlin Duan Yuzhu ma Wei Zhang Changlin Zheng Dongliang chao Fei Wang Yongyao Xia Wei Li Department of Chemistry Laboratory of Advanced Materials Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials State Key Laboratory of Molecular Engineering of Polymers College of Chemistry and Materials ScienceFudan University State Key Laboratory of Surface Physics and Department of Physics Fudan University

Due to their uncontrollable assembly and crystallization process,the synthesis of mesoporous metal oxide single crystals remains a formidable ***,we report the synthesis of single-crystal-like mesoporous Li2TiSiO5by using soft micelles as *** key lies in the atomic-scale self-assembly and step-crystallization processes,which ensure the formation of single-crystal-like mesoporous Li2TiSiO5microparticles via an oriented attachment growth mechanism under the confinement of an in-situ formed carbon *** mesoporous Li2TiSiO5anode achieves a superior rate capability(148 mah g-1at5.0 A g-1) and outstanding long-term cycling stability(138 mah g-1after 3000 cycles at 2.0 A g-1) for lithium storage as a result of the ultrafast Li+diffusion caused by penetrating mesochannels and nanosized crystal frameworks（5-10 nm）.In comparison,bulk Li2TiSiO5exhibits poor rate capability and cycle performance due to micron-scale diffusion *** method is very simple and reproducible,heralding a new way of designing and synthesizing mesoporous single crystals with controllable frameworks and chemical functionalities.

关键词： mesoporous materials micelles single-crystal-like Li2TiSiO5 lithium-ion batteries

Microwave-accelerated direct regeneration of LiCoO_(2)cathodes for Li-ion batteries

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Science China Chemistry 2024年第7期67卷 2181-2189页

作者： Xueshan Hu Yun-chao Yin chao Li Lihui Zhou Lin Yang Yitian feng Daxian Zuo Chenhui Ning Das Soham Sheng Dai Longbin Qiu Lin Zeng Haw Jiunn Woo Jiayu Wan Future Battery Research Center Global Institute of Future TechnologyShanghai Jiao Tong UniversityShanghai 200240China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Centre for Ionics University of malaya Department of PhysicsFaculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Key Laboratory for Advanced materials and Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China Department of Natural and Applied Sciences Duke Kunshan UniversityKunshan 215316China

Recycling spent lithium-ion batteries is integral to today's low-carbon environmental protection *** concept of direct regeneration,acknowledged for its environmental sustainability,economic viability,and consistent performance of recycled materials,is gaining *** study presents an efficient and nondestructive approach by utilizing an ultrafast microwave technology to directly regenerate spent lithium cobaltate(LCO)cathode *** contrast to conventional furnacebased processes,this method significantly reduces the regeneration *** subjecting the spent LCO mixed with lithium sources to three microwave heating cycles(at approximately 1,350 K),LCO regeneration is achieved,yielding a specific capacity of 140.8 mah g^(-1)(0.2 C)with a robust cycle *** further environmental and economic benefits,the ultrafast microwave technology holds scientific promise for directly regenerating cathode materials,while establishing competitiveness for industrial applications.

关键词： battery recycling spent lithium cobaltate microwave directly regeneration cathode materials

Microstructures and mechanical properties of a commercial Mg-Al-Zn-Mn alloy with various hot-extrusion processes

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Rare Metals 2024年第3期43卷 1329-1336页

作者： He ma Fan-Zhi Meng Qiang Yang Ze-feng Xie Yuan-Ding Huang Xin Qiu State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China School of materials Science and Engineering Changchun University of Science and TechnologyChangchun130022China magIC-magnesium Innovation Center Helmholtz-Zentrum Geesthacht21502GeesthachtGermany Engineering Research Center of Optoelectronic Functional materials Ministry of EducationChangchun University of Science and TechnologyChangchun130022China

Mg-Al-Zn-Mn(AZ)system alloys have become widely used due to their good castability,excellent formability and outstanding corrosion resistance[1-6].However,their strength is still much lower than that of traditional Mg... 详细信息

关键词： alloys alloy corrosion

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工程岩体完整性评价的实用方法研究

岩土力学 2010年第11期31卷 3579-3584页

作者：马超锋李晓成国文蒲丛林中国科学院地质与地球物理研究所工程地质力学重点实验室北京100029 中国科学院研究生院北京100049 河北省环境地质勘查院石家庄050021

采用结构面统计与结构面结合特征识别相结合的方法,从结构面几何发育特征和结合特征两方面评价工程岩体完整性。用体积节理数评价结构面几何发育特征,并引入岩体几何完整性系数Ig来表征。根据结构面张开度和充填胶结特征将其结合程度分... 详细信息

采用结构面统计与结构面结合特征识别相结合的方法,从结构面几何发育特征和结合特征两方面评价工程岩体完整性。用体积节理数评价结构面几何发育特征,并引入岩体几何完整性系数Ig来表征。根据结构面张开度和充填胶结特征将其结合程度分为5级,给出各级的定性特征描述,并引入结构面结合程度系数Ip对其量化。进而定义了岩体完整性指数将岩体完整性划分为完整、较完整、破碎、较破碎和极破碎5级,并给出对应的定性特征描述和Irm值区间。结合公路隧道工程实例,分别采用文中方法、声波测试法和体积节理数测量法对隧道围岩完整性进行了评价并对评价结果进行了比较。结果表明,文中方法得到的岩体完整性指数Irm与声波测试法得到的Kv基本一致,而体积节理数量测法的评价结果整体上大于声波测试方法。

关键词：工程地质岩体完整性评价结构面统计结构面结合特征体积节理数

Effect of Room Temperature Ultrasonic Vibration Compression on the Microstructure Evolution and Mechanical Properties of AZ91 Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第7期37卷 1135-1146页

作者： Ziyue Xu Huan Liu Luyao Li chao Sun Xi Tan Baishan Chen Qiangsheng Dong Yuna Wu Jinghua Jiang Jiang ma College of materials Science and Engineering Hohai UniversityNanjing210000China Suzhou Research Institute of Hohai University Suzhou215000China Shenzhen Key Laboratory of High Performance Nontraditional manufacturing College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen518060China Institute of Medical Devices(Suzhou) Southeast UniversitySuzhou215163China Institute for Advanced Study Central South UniversityChangsha410083China Jiangsu Key Laboratory of Advanced Structural materials and Application Technology Nanjing Institute of TechnologyNanjing211167China

To investigate the potential of direct ultrasonic vibration on improving the performance of magnesium alloys,this study first employed the ultrasonic vibration compression(UVC)on the solid solution treated AZ91 alloy,and explored its microstructure evolution and mechanical properties under *** only two seconds,the UVC alloys showed large deformation strains of 34.8–54.4%,and sudden increase of sample temperature to 243℃.Microstructure characterizations proved that UVC promoted the formation of abundant shear bands,fine grains,and the bimodal distribution of Mg17Al12 precipitates consisting of submicron particles located within the shear bands and nano-sized ones within the *** to the unique microstructure,the micro-hardness(and nano-hardness)value of UVC alloy was increased by 37.7%(35%)when compared with the solution-treated ***,the nano-modulus of the developed AZ91 alloy was also significantly increased to 62 GPa by statistical nanoindentation tests,which could be ascribed to increased Mg_(17)Al_(12) precipitates and decreased c/a value to some *** general,this work provides a new insight into the design and preparation of high-performance magnesium alloys by UVC at room temperature.

关键词： AZ91 alloys Ultrasonic vibration compression Precipitation Shear bands Mechanical properties