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High-current pulsed electron beam modification on microstructure and performance of Cu/CuW diffusion bonding joints

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Rare Metals 2024年第6期43卷 2819-2831页

作者： Na-Na Tian Cong-Lin Zhang Peng Lyu Jin-Tong Guan Jie Cai Qing-Feng Guan Shun Guo school of Materials Science and engineering Jiangsu University school of Material Science and engineering Yancheng Institute of Technology engineering Institute of Advanced Manufacturing and Modern Equipment Technology Jiangsu University

This study investigates the influence of high-current pulsed electron beam（HCPEB） modification on the microstructure and shear strength of Cu/CuW joints.Reliable solid-state diffusion bonding of modified-Cu（MCu） and modified-CuW（M-CuW） was achieved by HCPEB modification pretreatment at a temperature of 800-900 ℃ and a pressure of 5 MPa for 10-50 min.Experiments demonstrate that HCPEB modification facilitates the dissolution of W and Cu,resulting in the formation of a Cu0.4W0.6solid solution and thus enhancing the uniform distribution of microstructures.Additionally,HCPEB-induced defects play a beneficial role in promoting the diffusion process by providing fast diffusion paths for elements.The optimal joints with the maximum shear strength of 213.7 MPa were obtained through bonding M-Cu and M-CuW at 900℃ and 5 MPa for 30 min,which attributes to the combined effects of fine-grained strengthening and solid solution strengthening.Overall,the application of HCPEB modification showcases its effectiveness in promoting element diffusion and enhancing the mechanical performance of the joints.

关键词： HCPEB Element diffusion Shear strength Crystal defects Surface modification

Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1540-1553页

作者： Jingcheng Wang Zhentong Liu Wei Chen Hongliang Chen Lifeng Zhang school of Mechanical engineering Yanshan UniversityQinhuangdao 066004China school of Materials Science and engineering Tianjin UniversityTianjin 300350China school of Mechanical and Materials engineering North China University of TechnologyBeijing 100144China

A 3D mathematical model was proposed to investigate the molten steel–slag–air multiphase flow in a two-strand slab continuous casting(CC)tundish during ladle change.The study focused on the exposure of the molten steel and the subsequent reoxidation occurrence.The exposure of the molten steel was calculated using the coupled realizable k–εmodel and volume of fluid(VOF)model.The diffusion of dissolved oxygen was determined by solving the user-defined scalar(UDS)equation.Moreover,the user-defined function(UDF)was used to describe the source term in the UDS equation and determine the oxidation rate and oxidation position.The effect of the refilling speed on the molten steel exposure and dissolved oxygen content was also discussed.Increasing the refilling speed during ladle change reduced the refilling time and the exposure duration of the molten steel.However,the elevated refilling speed enlarged the slag eyes and increased the average dissolved oxygen content within the tundish,thereby exacerbating the reoxidation phenomenon.In addition,the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling speed.When the inlet speed was 3.0 m·s^(-1)during ladle change,the molten steel with a high dissolved oxygen content exited the outlet in a short period,reaching a maximum dissolved oxygen content of 0.000525wt%.Conversely,when the inlet speed was 1.8 m·s^(-1),the maximum dissolved oxygen content was 0.000382wt%.The refilling speed during the ladle change process must be appropriately decreased to minimize reoxidation effects and enhance the steel product quality.

关键词： tundish ladle change reoxidation multiphase flow numerical simulation

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Catalytic asymmetric(3 + 3) cycloaddition between different 2-indolylmethanols

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Science China Chemistry 2024年第8期67卷 2629-2636页

作者： Tianzhen Li Sijia Liu Shufang Wu Qi Cheng Qun Chen Yinchun Jiao Yuchen Zhang Feng Shi school of Petrochemical engineering School of Materials Science & Engineering Changzhou University Research Center of Chiral Functional Heterocycles School of Chemistry and Materials Science Jiangsu Normal University school of Chemistry and Chemical engineering Hunan University of Science and Technology school of Chemistry and Chemical engineering Henan Normal University

The catalytic asymmetric(3 + 3) cycloaddition between different 2-indolylmethanols has been established, in which a series of chiral indole-fused six-membered heterocycles were constructed in high yields with excellent enantioselectivities. This work not only has established the first catalytic asymmetric cycloaddition between different 2-indolylmethanols but also provided a powerful strategy for constructing enantioenriched indole-fused six-membered rings. Additionally, biological evaluation discovered some products with promising antitumor activities. Notably, theoretical calculations performed on the reaction pathway and activation mode provide an in-depth understanding of this catalytic asymmetric(3 + 3) cycloaddition among different 2-indolylmethanols, which will advance the understanding of the chemistry of indolylmethanols.

关键词： 2-indolylmethanol asymmetric organocatalysis chiral phosphoric acid cycloaddition enantioselectivity

On-surface synthesis and characterization of polyynic carbon chains

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National Science Review 2024年第3期11卷 192-199页

作者： Wenze Gao Wei Zheng Luye Sun Faming Kang Zheng Zhou Wei Xu Interdisciplinary Materials Research Center School of Materials Science and Engineering Tongji University

Carbyne, an elusive sp-hybridized linear carbon allotrope, has fascinated chemists and physicists for decades. Due to its high chemical reactivity and extreme instability, carbyne was much less explored in contrast to the sp2-hybridized carbon allotropes such as graphene. Herein, we report the on-surface synthesis of polyynic carbon chains by demetallization of organometallic polyynes on the Au（111） surface;the longest one observed consists of ～60 alkyne units（120 carbon atoms）. The polyynic structure of carbon chains with alternating triple and single bonds was unambiguously revealed by bond-resolved atomic force microscopy. Moreover, an atomically precise polyyne, C14, was successfully produced via tip-induced dehalogenation and ring-opening of the decachloroanthracene molecule(C14Cl10) on a bilayer NaCl/Au（111） surface at 4.7 K, and a band gap of 5.8 eV was measured by scanning tunnelling spectroscopy,in a good agreement with the theoretical HOMO–LUMO gap（5.48 eV）.

关键词： polyyne scanning probe microscopy carbon allotrope on-surface synthesis organometallic polyyne

Compositional evolution for mixed aerosols containing gluconic acid and typical nitrate and the effect of multiply factors on hygroscopicity

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Journal of Environmental Sciences 2024年第5期139卷 206-216页

作者： Yue Zhu Shufeng Pang Yunhong Zhang school of Chemistry and Chemical engineering Beijing Institute of TechnologyBeijing 100081China

The aging process of atmospheric aerosols usually leads to a mixture of inorganic salts and organic compounds of anthropogenic origin.In organic compounds,polyhydroxy organic acids are important components,however,the study on composition and hygroscopic properties of the mixture containing inorganics and polyhydroxy organic acids is scanty.In this study,gluconic acid,the proxy of polyhydroxy organic acids,is mixed with the representative nitrate(Mg(NO_(3))_(2),Ca(NO_(3))_(2))to form aerosols.ATR-FTIR and optical microscopy are employed to study the component changes and hygroscopicity as a function of relative humidity.As relative humidity fluctuates,the FTIR-ATR spectra display that the internal mixed gluconic acid(CH_(2)(CH)_(4)(OH)_(5)COOH)and nitrate can react to release acidic gases,forming relevant gluconate and further affecting the hygroscopicity.The specific presentation is particles cannot be recovered to their original size after the dehydration-hydration process and there will be some disparities in GF for mixed particles.For the gluconic acid-Ca(NO_(3))_(2)/Mg(NO_(3))_(2)mixtures with molar ratios of 1:1,higher degree of reaction resulting in the production of large amounts of gluconate should be responsible to the lower hygroscopicity compared to ZSR model.For 1:2 gluconic acid-nitrate mixed systems(with higher nitrate content),the hygroscopicity of mixtures are higher than the ZSR prediction.A possible reason could be‘salt-promoting effect’on the organic fractions of the surplus inorganic salt in the mixture.These data can improve the chemical composition list evaluation,in turn hygroscopic properties and phase state of atmospheric aerosol,and then the climate effect.

关键词： Hygroscopicity Gluconic acid Reaction ZSR simulation Size growth factors

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Hierarchical V3S4/C nanofibers with fast kinetics for superior alkali metal batteries

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Rare Metals 2024年第4期43卷 1836-1844页

作者： Li Chen Zhi-Xin Rao Zhi Chen Zhao-Hui Wu Shuai Yang Zhi-Jun Feng Hui-Yong Yang Fan-Yan Zeng Xi-Bao Li Jin-Yang Hu Jun-Tong Huang school of Materials Science and engineering Nanchang Hangkong University school of Aeronautical Manufacturing engineering Nanchang Hangkong University

Owing to the numerous benefits,including low cost and great theoretical capacity,V3S4 has been a research hotspot for Li+/Na+/K+storage.Nonetheless,the V3S4electrode with long cycling stability and high specific capacities continues to pose significant challenges.In this work,vacuum vulcanization is combined with electrospinning to synthesize V3S4/C composite nanofibers （V3S4@CNF）.

关键词： Sulfur compounds

Nickel Sulfide Modified NiCu Nanoalloy with Excellent Oxygen Evolution Reaction Properties Prepared through Electrospinning and Heat Treatment

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 320-326页

作者：李涛凌帅 ZHONG Shujie LOU Qiongyue Department of Materials engineering School of Mechanical EngineeringChengdu UniversityChengdu 610106China

Ni^(2+)/Cu^(2+)/SO_(4)^(2-)/polyvinyl alcohol precursor fibers with uniform diameters were prepared through electrospinning.Nickel-based composite nanoalloys containing Ni,Cu,and S were prepared through heat treatment in an Ar atmosphere.The experimental results show that the main components of the prepared nanoalloys are NiCu,Ni_(3)S_(2),Ni,and C.The nanoalloys exhibit fine grain sizes about 200-500 nm,which can increase with increasing heat treatment temperature.Electrochemical test results show that the nickel sulfidemodified NiCu nanoalloy composites exhibit excellent oxygen evolution reaction properties,and the oxygen evolution reaction properties gradually improve with the increasing heat treatment temperature.The sample prepared at 1 000℃ for 40 min show a low overpotential of 423 mV and a small Tafel slope of 134 mV·dec^(-1) at a current density of 10 mA·cm^(-2).

关键词： NiCu nanoalloy Ni_(3)S_(2) structure transformation oxygen evolution reaction

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A laser-engraved wearable gait recognition sensor system for exoskeleton robots

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Microsystems & Nanoengineering 2024年第2期10卷 269-277页

作者： Maowen Sun Songya Cui Zezheng Wang Huayu Luo Huayong Yang Xiaoping Ouyang Kaichen Xu State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou310027China school of Information and Electrical engineering Hangzhou City UniversityHangzhou310015China

As a reinforcement technology that improves load-bearing ability and prevents injuries,assisted exoskeleton robots have extensive applications in freight transport and health care.The perception of gait information by such robots is vital for their control.This information is the basis for motion planning in assistive and collaborative functions.Here,a wearable gait recognition sensor system for exoskeleton robots is presented.Pressure sensor arrays based on laser-induced graphene are developed with flexibility and reliability.Multiple sensor units are integrated into an insole to detect real-time pressure at key plantar positions.In addition,the circuit hardware and the algorithm are designed to reinforce the sensor system with the capability of gait recognition.The experimental results show that the accuracy of gait recognition by the proposed system is 99.85%,and the effectiveness of the system is further verified through testing on an exoskeleton robot.

关键词： hardware robot skeleton

Re-delocalization of localized d-electrons in VO2（R）-VS4 hetero-structure enables high performance of rechargeable Mg-ion batteries

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Journal of Magnesium and Alloys 2024年第5期12卷 1830-1840页

作者： Lijiao Zhou Chao Shen Xueyang Hou Zhao Fang Ting Jin Keyu Xie school of Materials Science and engineering Northwestern Polytechnical University school of Metallurgical engineering Xi'an University of Architecture and Technology

Rechargeable Mg-ion batteries（MIBs） have attracted much more attentions by virtue of the high capacity from the two electrons chemistry.However, the reversible Mg2+diffusion in cathode materials is restricted by the strong interactions between the high-polarized bivalent Mg2+ions and anionic lattice. Herein, we design and propose a hetero-structural VO2（R）-VS4cathode, in which the re-delocalized d-electrons can effectively shield the polarity of Mg2+ions. Theoretically, the electrons should spontaneously transfer from VS4to VO2（R） through the interfaces of hetero-structure due to the lower work function value of VS4. Furthermore, the internal electrons transfer lead to the electronic injection into VO2（R） from VS4and the partially broken V-V dimers, indicating the presence of lone pair electrons and charge re-delocalization. Benefiting from the shield effect of re-delocalized electrons, and the weakened attraction between cations and O/S anions enables more S2--S22-redox groups to participate the electrochemical reactions and compensate the double charge of Mg2+ions. Accordingly,VO2（R）-VS4hetero-structure exhibits a high specific capacity of 554 mA h g-1at 50 mA g-1. It is believed that the charge re-delocalization of cathode extremely boost the Mg2+ions migration for the high-capacity of MIBs.

关键词： Mg-ion batteries Cathode Charge delocalization Electronic structure Heterostructure