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Asymmetric Drying and Wetting Trends in Eastern and Western China

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Advances in Atmospheric Sciences 2024年第2期41卷 221-232页

作者： wen wu Fei ji Shujuan HU Yongli HE College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China Collaborative Innovation Center for Western Ecological Safety Lanzhou UniversityLanzhou 730000China

As an important factor that directly affects agricultural production, the social economy, and policy implementation,observed changes in dry/wet conditions have become a matter of widespread concern. However, previous research has mainly focused on the long-term linear changes of dry/wet conditions, while the detection and evolution of the non-linear trends related to dry/wet changes have received less attention. The non-linear trends of the annual aridity index, obtained by the Ensemble Empirical Mode Decomposition(EEMD) method, reveal that changes in dry/wet conditions in China are asymmetric and can be characterized by contrasting features in both time and space in China. Spatially, most areas in western China have experienced transitions from drying to wetting, while opposite changes have occurred in most areas of eastern China. Temporally, the transitions occurred earlier in western China compared to eastern China. Research into the asymmetric spatial characteristics of dry/wet conditions compensates for the inadequacies of previous studies, which focused solely on temporal evolution;at the same time, it remedies the inadequacies of traditional research on linear trends over centennial timescales. Analyzing the non-linear trend also provides for a more comprehensive understanding of the drying/wetting changes in China.

关键词： aridity index EEMD dry/wet conditions asymmetric evolution

Asymmetric Cyclopropanation Catalyzed by a Copper-(Schiff-base) Complex with Double Chiral Centers

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Chemical Research in Chinese Universities 2003年第2期19卷 238-239页

作者： jiANG Chang sheng LI You gui jiANG Chen wen ji wu YOU Tian pa Department of Chemistry Universtity of Science&Technology of ChinaHefei 230026 P.R.China

The catalytic asymmetric cyclopropanation of olefins with diazoacetate esters has been one of the most important methodologies for the formation of chiral cyclopropane compounds[1,2].……

关键词： Asymmetric cyclopropanation Catalysis Copper-(Schiff-base)

Hydrothermal Preparation and Photophysical Properties of a Ni(Ⅱ) Complex Containing Quinoline Derivative and Phen Ligands

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Chinese Journal of Structural Chemistry 2021年第4期40卷 501-506,408页

作者： CHEN Hai-Hui YI Xiu-Guang PAN Chang-Wang wen ji-wu ZHANG Cong School of Chemistry and Chemical Engineering Jinggangshan UniversityJi’anJiangxi 343009China

A novel nickel complex[Ni_(2)L_(2)Phen_(3)]·3H_(2)O (HL=3-hydroxy-2-methylquioline-4-carboxylic acid)has been synthesized by a hydrothermal approach and is structurally determined by single-crystal X-ray *** title complex crystallizes in triclinic space group *** data for the title complex:C58H44N8Ni2O9,Mr=1108.35,a=11.8648(4),b=12.7369(4),c=17.0728(5)A,α=97.694(3),β=96.702(2),γ=99.566(3)°,V=2495.66(14)A^(3),Z=2,T=293(2) K,Dc=1.475 g/cm^(3),μ(Mo Kα)=0.824 mm^(–1),F(000)=1140,R=0.0757,w R=0.2129 and GOF=*** nickel ions are surrounded by five oxygen and six nitrogen atoms to yield two slightly distorted octahedral ***-state photoluminescence spectrum reveals that it shows blue purple ***-state UV/Vis diffuse reflectance spectroscopy exhibits that it has an optical band gap of 1.702 e V.

关键词： hydrothermal preparation crystal structure photophysical properties

Enhanced thermoelectric and mechanical properties of Bi_(0.5)Sb_(1.5)Te_(3) alloy with dispersed yttrium oxide ceramic nanoparticles

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Rare Metals 2024年第4期43卷 1758-1768页

作者： Cun-Cheng Li Ming-Wei Zhang ji-wu Xin Lei Wei wen-Yu Zhao School of Materials Science and Engineering Shandong University of TechnologyZibo255000China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore639798Singapore State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China

Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based *** ceramic nanoparticles are good candidates for achieving this *** this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma *** to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were *** measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical ***,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal ***,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the *** addition,the Vickers hardness of the composite material was 35%higher than that of the *** study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.

关键词： Bi_(0.5)Sb_(1.5)Te_3 alloy Y_(2)O_(3) ceramic nanoparticles Microstructures Thermoelectric performance Mechanical properties

Ultra-high-temperature application of MXene: Stabilization of 2D Ti_(3)C_(2)T_(x) for cross-scale strengthening and toughening of 3D TiC

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Journal of Advanced Ceramics 2024年第1期13卷 1-10页

作者： Lu Liu Guobing Ying Quanguo jiang Dong wen Peng Wang Meng wu Ziying ji Yongting Zheng Xiang Wang Department of Materials Science and Engineering College of Mechanics and MaterialsHohai UniversityNanjing 211100China Key Laboratory of Superlight Materials&Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin 150001China Shenzhen Key Laboratory for Advanced Materials School of Materials Science and EngineeringHarbin Institute of Technology(Shenzhen)Shenzhen 518055China Center for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150001China

Transition metal carbide/nitride cores within MXenes make them considerably useful for ultra-high-temperature ***,extensive research on Ti_(3)C_(2)T_(x) MXene has revealed its tendency to undergo a phase transition to TiCy at temperatures above 800℃due to high activity of a superficial Ti atomic ***,spark plasma sintering of Ti_(3)C_(2)T_(x) and TiC is performed to prevent the Ti_(3)C_(2)T_(x) phase transition at temperatures up to 1900℃through the fabrication of composites at a pressure of 50 *** a focused ion beam scanning electron microscope to separate layered substances in the composites and examining selected area diffraction spots in a transmission electron microscope enabled identification of non-phase-transitioned ***-principles calculations based on density functional theory indicated the formation of strong chemical bonding interfaces between Ti_(3)C_(2)T_(x) and TiC,which imposed a stability constraint on the Ti atomic layer at the Ti_(3)C_(2)T_(x) *** performance tests,such as three-point bending and fracture toughness analysis,demonstrated that the addition of Ti_(3)C_(2)T_(x) can effectively improve the cross-scale strengthening and toughening of the TiC matrix,providing a new path for designing and developing two-dimensional(2D)carbides cross-scale-enhanced three-dimensional(3D)carbides with the same elements relying on a wide variety of MXenes.

关键词： MXene ultra-high-temperature phase stability interface bonding cross-scale strengthening and toughening structural ceramic composites

Effect of Nb-content on the corrosion resistance of Co-free high entropy alloys in chloride environment

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Tungsten 2024年第4期6卷 778-793页

作者： Peng-Fei Dai Yang Zhang Sergey Rogozhkin ji-Hong Han Shu-wen Li Zhong-wu Zhang Key Laboratory of Superlight Materials and Surface Technology Ministry of Education College of Materials Science and Chemical Engineering Harbin Engineering University National Research Nuclear University “MEPh I” National Research Center “Kurchatov Institute”

This study investigated the effect of Nb-content on the corrosion behavior of the Al7Cr20Fe35-xNi35Mo3Nbx（x=0,1 and 2）high-entropy alloys in a *** results indicated that only the face centered cubic phase existed in the NbO and Nbl alloys,while the emergence of Laves phase was observed when Nb-content reached 2 at.%.The NbO and Nb1alloys exhibited pitting corrosion,while the NiAl-rich phase experienced localized preferential corrosion in the Nb2 *** electrochemical results revealed that the corrosion current density of the Nbx（x=0,1 and 2） alloys fell within the range of 10-8-10-7A·cm-2,with a pitting corrosion potential exceeding 700 ***,the Nb1 alloy exhibited the most impressive corrosion resistance,as its corrosion current density(7 × 10-8A·cm-2) was merely half that of 316LN stainless *** is attributed to its rapid passivation process,resulting in the development of a protective film characterized by an increased Cr2O3/Al2O3+Cr（OH）*** study highlighted that the addition of Nb contributed to gram refinement,decreased corrosion current density,and elevated pitting potential,favoring passivation and improving corrosion ***,excessive Nb-content resulted in the emergence of the Laves phase,inducing galvanic corrosion and diminishing resistance to corrosion.

关键词： Corrosion High entropy alloys Microstructure Niobium Passive film

Methanol steam reforming for hydrogen production driven by an atomically precise Cu catalyst

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Green Energy & Environment 2024年第7期9卷 1079-1084页

作者： Weigang Hu Haoqi Liu Yuankun Zhang jiawei ji Guangjun Li Xiao Cai Xu Liu wen wu Xu Weiping Ding Yan Zhu School of Chemistry and Chemical Engineering Nanjing University School of Physical Science and Technology Ningbo University

Plasmon-induced hot-electron transfer from metal nanostructures is being intensely pursed in current photocatalytic research,however it remains elusive whether molecular-like metal clusters with excitonic behavior can be used as light-harvesting materials in solar energy utilization such as photocatalytic methanol steam *** this work,we report an atomically precise Cu13cluster protected by dual ligands of thiolate and phosphine that can be viewed as the assembly of one top Cu atom and three *** Cu13H10（SR）3（PR’3）7(SR=2,4-dichlorobenzenethiol,PR’3=P（4-FC6H4）3) cluster can give rise to highly efficient light-driven activity for methanol steam reforming toward H2production.

关键词： Nanocluster Photocatalysis Methanol steam reforming Atomically precise Copper catalyst

Index-free triangle-based graph local clustering

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Frontiers of Computer Science 2024年第3期18卷 143-153页

作者： Zhe YUAN Zhewei WEI Fangrui LV ji-Rong wen The Country and Area Studies Academy Beijing Foreign Studies UniversityBeijing 100089China Gaoling School of Artificial Intelligence Renmin University of ChinaBeijing 100872China

Motif-based graph local clustering(MGLC)is a popular method for graph mining tasks due to its various ***,the traditional two-phase approach of precomputing motif weights before performing local clustering loses locality and is impractical for large *** some attempts have been made to address the efficiency bottleneck,there is still no applicable algorithm for large scale graphs with billions of *** this paper,we propose a purely local and index-free method called Index-free Triangle-based Graph Local Clustering(TGLC^(*))to solve the MGLC problem w.r.t.a ***^(*)directly estimates the Personalized PageRank(PPR)vector using random walks with the desired triangleweighted distribution and proposes the clustering result using a standard sweep *** demonstrate TGLC^(*)’s scalability through theoretical analysis and its practical benefits through a novel visualization ***^(*)is the first algorithm to solve the MGLC problem without precomputing the motif *** experiments on seven real-world large-scale datasets show that TGLC^(*)is applicable and scalable for large graphs.

关键词： graph local clustering triangle motif index-free sampling method visualization

Adaptive joint configuration optimization for collaborative inference in edge-cloud systems

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Science China(Information Sciences) 2024年第4期67卷 335-336页

作者： Zheming YANG wen ji Zhi WANG Institute of Computing Technology Chinese Academy of Sciences University of Chinese Academy of Sciences Peng Cheng Laboratory Tsinghua Shenzhen International Graduate School Tsinghua University

With the rapid development of technologies such as deep learning and the Internet of Things(IoT), the deployment and application of various IoT devices are becoming increasingly widespread, resulting in the inference tasks generated increasing dramatically [1]. Many deep neural network(DNN) models are deployed on servers for performing inference tasks.

关键词： Inference engines