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Current-carrying tribological behavior of C/Cu contact pairs in extreme temperature and humidity environments for railway catenary systems

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Science China Technological Sciences 2024年

作者： SHEN MingXue JI Dehui hu qiang XIAO Li LI QiuPing State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University School of Materials Science and Engineering East China Jiaotong University Institute of Applied Physics Jiangxi Academy of Sciences

Many current-carrying contact pairs, such as those found in pantograph-catenary systems, operate in open environments and are susceptible to significant external interference from temperature and humidity variations. This study investigated the evolution of the friction coefficient and contact resistance of C/Cu contact pairs under alternating temperature, humidity, and current conditions. Through experimentation, the wear rate and microtopography of the worn surface were analyzed under various constant parameters. Subsequently, the differences in tribological behavior and current-carrying characteristics of the contact pairs under these three parameters were explored. The results revealed that the decrease in temperature resulted in a significant increase in the friction coefficient of the contact pairs, carbon wear, and copper surface roughness. Additionally, the surface oxidation rate was lower at lower temperatures. Moreover, contact resistance did not consistently increase with decreasing temperature, owing to the combined action of the contact area and the oxide film. Compared with temperature, humidity fluctuations at room temperature exerted less influence on the friction coefficient and contact resistance of the contact pairs. Dry environments rendered carbon materials vulnerable to oxidation and cracking, while excessive humidity fostered abrasive wear and arcing. High-current conditions generally degraded the tribological properties of C/Cu contacts. In the absence of current, the friction coefficient was extremely high, and the copper transfer was high. Under excessive current, copper was susceptible to plowing by carbon micro-bumps and abrasive particles, resulting in a decrease in the friction coefficient. The release of lipids from the carbon surface due to temperature elevation weakened the electrical contact performance and increased the occurrence of arc erosion, thereby exacerbating carbon wear.

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Optimizing magnetoelastic properties by machine learning and high-throughput micromagnetic simulation

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Rare Metals 2024年第5期43卷 2251-2262页

作者： Jian-hu Gong Zheng-Ming Zhang Cheng-Liang Zhang Peng-qiang hu Chao Zhou Dun-hui Wang Sen Yang Division of Microelectronic Materials and Devices Hangzhou Dianzi University School of Physics MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University National Laboratory of Solid State Microstructures Nanjing University

Magnetoelastic couplings in giant magnetostrictive materials （GMMs） attract significant interests due to their extensive applications in the fields of spintronics and energy harvesting devices.Understanding the role of the selection of materials and the response to external fields is essential for attaining desired functionality of a GMM.Herein,machine learning （ML） models are conducted to predict saturation magnetostrictions （λs） in RFe2-type （R=rare earth） GMMs with different compositions.According to ML-predicted composition–λsrelations,it is discovered that the values ofλshigher than1100×10–6are almost situated in the composition space surrounded by 0.26≤x≤0.60 and 1.90≤y≤2.00 for the ternary compounds of TbxDy1-xFey.Assisted by ML predictions,the compositions are further narrowed down to the space surrounded by 0.26≤x≤0.32 and 1.92≤y≤1.97 for the excellent piezomagnetic （PM） performance in the TbxDy1-xFey-based PM device through our developed high-throughput （HTP） micromagnetic simulation（MMS） algorithm.Accordingly,high sensitivities up to10.22–13.61 m T·MPa–1are observed in the optimized range within which the available experimental data fall well.This work not only provides valuable insights toward understanding the mechanism of magnetoelastic couplings,but also paves the way for designing and optimizing highperformance magnetostrictive materials and PM sensing devices.

关键词： Magnetostriction Piezomagnetic effect Machine learning Micromagnetic simulation

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Copper-catalyzed C(sp)-H aryl amination enables modular synthesis of quinolines and 2-quinolinones

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Science China Chemistry 2024年第2期67卷 595-603页

作者： Yang Gao Haixia Li Simin Yang Yanping huo Qian Chen Xianwei Li Zhe Wang Xiao-qiang hu School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou510006China Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory Jieyang515200China Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education&hubei Key Laboratory of Catalysis and Materials Science School of Chemistry and Materials ScienceSouth-Central University for NationalitiesWuhan430074China

Herein,we disclose a novel copper-catalyzed C(sp)-H aryl amination of terminal alkynes with anthranils,enabling the rapid generation of highly reactive secondary N-aryl ynamines for the modular synthesis of structurally diverse C2-substituted quinolines and 2-quinolinones.The in-situ formed carbonyl-ynamines are prone to tautomerize to carbonyl-ketenimines,which can efficiently react with a series of nucleophiles,including amines,alcohols,phenols,thiols,thiophenols,active-methylene compounds,and even water to produce various quinoline derivatives with the generation of H_(2)O as a sole and green byproduct.This method also unlocks a practical route to create various quinoline-fused heterocycles and can be successfully applied to the late-stage modification of complex molecules and the concise synthesis of bioactive targets.Mechanistic studies reveal a coppercatalyzed inner-sphere nitrene transfer process by using anthranils as novel aryl nitrene precursors.

关键词： copper catalysis anthranils C(sp)-H aryl amination carbonyl-ketenimines quinolines

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Brain abscess from oral microbiota approached by metagenomic next-generation sequencing: A case report and review of literature

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World Journal of Clinical Cases 2024年第3期12卷 616-622页

作者： Xue-Min Zhu Chun-Xia Dong Lei Xie Hao-Xin Liu huai-qiang hu School of Clinical Medicine Weifang Medical UniversityWeifang 261053Shandong ProvinceChina Department of Neurology the 960th Hospital of People′s Liberation ArmyJinan 250031Shandong ProvinceChina

BACKGROUND Brain abscess is a serious and potentially fatal disease caused primarily by microbial infection.Although progress has been made in the diagnosis and treatment of brain abscesses,the diagnostic timeliness of pathogens needs to be improved.CASE SUMMARY We report the case of a 54-year-old male with a brain abscess caused by oral bacteria.The patient recovered well after receiving a combination of metagenomic next-generation sequencing(mNGS)-assisted guided medication and surgery.CONCLUSION Therefore,mNGS may be widely applied to identify the pathogenic microor-ganisms of brain abscesses and guide precision medicine.

关键词： Brain abscess Metagenomic next-generation sequencing Periodontitis Oral bacteria Precision medicine Case report

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Role of targeting ferroptosis as a component of combination therapy in combating drug resistance in colorectal cancer

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World Journal of Clinical Oncology 2024年第3期15卷 375-377页

作者： Xiao-Ting Xie qiang-hu Pang Lian-Xiang Luo The First Clinical College Guangdong Medical UniversityZhanjiang 524023Guangdong ProvinceChina The Marine Biomedical Research Institute Guangdong Medical UniversityZhanjiang 524023Guangdong ProvinceChina

Colorectal cancer(CRC)is a form of cancer that is often resistant to chemotherapy,targeted therapy,radiotherapy,and immunotherapy due to its genomic instability and inflammatory tumor microenvironment.Ferroptosis,a type of non-apoptotic cell death,is characterized by the accumulation of iron and the oxidation of lipids.Studies have revealed that the levels of reactive oxygen species and glutathione in CRC cells are significantly lower than those in healthy colon cells.Erastin has emerged as a promising candidate for CRC treatment by diminishing stemness and chemoresistance.Moreover,the gut,responsible for regulating iron absorption and release,could influence CRC susceptibility through iron metabolism modulation.Investigation into ferroptosis offers new insights into CRC pathogenesis and clinical management,potentially revolutionizing treatment approaches for therapy-resistant cancers.

关键词： Colorectal cancer Ferroptosis Immunotherapy Drug resistance Chemotherapy Nanodrug delivery systems

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Helcionelloids from the Cambrian Fortunian of the Northern Yangtze Platform,China

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Acta Geologica Sinica(English Edition) 2023年第6期97卷 1587-1603页

作者： ZHANG Mengshao PANG Yanchun YANG Ben HE Yangjian LIANG Siyu hu qiang LIN Li Institute of Sedimentary Geology Chengdu University of TechnologyChengdu 610059China Shanxi Geological Exploration Bureau 214 Geological Team Co. Ltd.YunchengShanxi 044000China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China College of Earth Sciences Chengdu University of TechnologyChengdu 610059China

A study of the morphological and microstructural characteristics of helcionelloids from the Nanjiang area(north Sichuan,China)at the northern Yangtze Platform was undertaken,in order to understand their phylogenetic position.Helcionelloids fossils from the Kuanchuanpu Formation of the Changtanhe–Maolinzi section include 7 genera and 11 species.There are distinct differences in the degree of shell bending,the apical morphology and apex position,the outline of the aperture and the height of the shell,all of which constitute important identification features.Although helcionelloid apices exhibit varying degrees of rotation towards the aperture,they do not show any signs of evident distortion.A pair of basally-symmetrical muscle scars are discovered on the shells of helcionelloids(such as Bemella simplex),showing a distinct difference when compared with those of the stem-group gastropod(e.g.,Pelagiella).The prismatic shell layer of helcionelloids has been observed,which are common components in Cambrian molluscs,but differ significantly from the dense layer microstructure found in contemporary molluscs.The microstructures,muscle scars and morphological characteristics demonstrate that helcionelloids represent a stem-group of molluscs.

关键词： helcionelloids mollusc muscle scar Cambrian Fortunian Yangtze Platform

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The Grad-Shafranov reconstruction in twenty years: 1996–2016

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Science China Earth Sciences 2017年第8期60卷 1466-1494页

作者： hu qiang Department of Space Science and CSPAR University of Alabama in Huntsville

We review and summarize the applications of the Grad-Shafranov(GS) reconstruction technique to space plasma structures in the Earth's magnetosphere and in the interplanetary space. We organize our presentations following the branches of the "academic family tree" rooted on Prof. Bengt U. ? Sonnerup, the inventor of the GS method. Special attentions are paid to validations of the GS reconstruction results via(1) the direct validation by co-spatial in-situ measurements among multiple spacecraft, and(2) indirect validation by implications and interpretations of the physical connection between the structures reconstructed and other related processes. For the latter, the inter-comparison and interconnection between the large-scale magnetic flux ropes(i.e., Magnetic Clouds) in the solar wind and their solar source properties are presented. In addition, we also summarize various GS-type(or-like) reconstruction and an extension of the GS technique to toroidal geometry. In particular,we point to a possible advancement with added complexity of "helical symmetry" and mixed helicity, in the hope of stimulating interest in future development. We close by offering some thoughts on appreciating the scientific merit of GS reconstruction in general.

关键词： GS方法重构重建技术行星际空间现场测量有限空间物理连接结构重建

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“5W”传播模式下中国非物质文化遗产对外传播的研究现状与路径探索

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西安外国语大学学报 2024年第2期32卷 93-98页

作者：胡强欧阳晓芬湘潭大学外国语学院

本研究基于中国知网数据库,对2013—2022年“中国非物质文化遗产对外传播”相关期刊论文进行检索分析,以“5W”传播模式为理论框架,从传播主体与传播效果、传播内容与传播效果、传播渠道与传播效果三个方面,梳理了近十年中国非遗对外传... 详细信息

本研究基于中国知网数据库,对2013—2022年“中国非物质文化遗产对外传播”相关期刊论文进行检索分析,以“5W”传播模式为理论框架,从传播主体与传播效果、传播内容与传播效果、传播渠道与传播效果三个方面,梳理了近十年中国非遗对外传播的研究成果,呈现出以下三个特点:一是我国沿海省份的传播主体更加重视非遗对外传播的研究;二是研究对于传播内容细化的关注度不够,同一类别研究下的特定非遗项目呈现单一化;三是研究探讨的传播渠道呈现多元化、市场化发展的态势。为进一步推进我国非遗的对外传播,今后研究应该重视特定非遗类别和特定非遗项目的研究,运用人工智能+大数据等前沿领域的成果展开跨学科研究,同时强化民俗认同视角下“复调传播”多元格局构建的研究。

关键词： “5W”传播模式非物质文化遗产对外传播复调传播

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Unraveling enhanced membrane lipid biosynthesis in Chlamydomonas reinhardtii starchless mutant sta6 by using an electrospray ionization mass spectrometry-based lipidomics method

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Journal of Oceanology and Limnology 2020年第3期38卷 783-794页

作者： ZANG Zhengrong LI Yanhua hu qiang HAN Danxiang Center for Microalgal Biotechnology and Biofuels Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China Key Laboratory for Algal Biology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China Laboratory for Marine Biology and Biotechnology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China Beijing Key Laboratory of Algae Biomass Microalgae Biotechnology CenterSDIC Biotech Investment Co.Ltd.State Development&Investment Corp.Beijing 100142China

The unicellular green alga Chlamydomonas reinhardtii,a well-established model organism,has been widely used in dissecting glycerolipid metabolism in oxygenating photosynthetic organisms.In previous studies,it has been found that shunting carbon precursors from the starch synthesis pathway can lead to a 10-fold increase in TAG content as compared to the wild type,but it is unknown whether inactivation of AGPase may affect membrane lipids biosynthesis.The study aims to investigate global changes in lipid metabolism and homeostasis in the starchless mutant C.reinhardtii sta6.By utilizing an electrospray ionization/mass spectrometry(ESI/MS)-based lipidomics approach,a total of 105 membrane lipid molecules of C.reinhardtii were resolved,including 16 monogalactosyldiacylglycerol(MGDG),16 digalactosyldiacylglycerol(DGDG),11 phosphatidylglycerol(PG),6 sulfoquinovosyldiacylglycerol(SQDG),49 diacylglyceryl-N,N,N-trimethylhomoserine(DGTS),2 phosphatidylethanolamine(PE),and 5 phosphatidylinositol(PI)molecules.The quantitative results indicated that the membrane lipid profiles were similar between the two C.reinhardtii strains grown under both low-and high-light conditions,but the cellular contents of a great number of lipids were altered in sta6 due to the defect in starch biosynthesis.Under low-light conditions,sta6 accumulated more PI,MGDG,DGDG but less amounts of DGTS as compared to WT.Under high light,sta6 cells contained higher content membrane lipids than cc-124,except for PG,which is more or less similar in both strains.Our results demonstrate that the cellular membrane lipid homeostasis underwent profound changes in the starchless mutant,and thereby its physiological impact remains to be explored.

关键词： Chlamydomonas reinhardtii chloroplast lipidomes extraplastidic lipidomes electrospray ionization mass spectrometry

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电商平台与竞争性商家数据赋能策略研究

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中国管理科学 2024年第6期32卷 46-56页

作者：胡强谢家平张广思上海财经大学商学院上海200433 上海财经大学浙江学院浙江金华321013 新疆财经大学工商管理学院新疆乌鲁木齐830012

随着数字经济的发展,平台型企业凭借大数据技术优势向入驻商家实施数据赋能策略,帮助平台与商家实现价值共创。本文考虑具有竞争关系的两个商家入驻同一电商平台,平台向商家有偿提供数据赋能服务,运用Hotelling模型刻画市场需求,构建电... 详细信息

随着数字经济的发展,平台型企业凭借大数据技术优势向入驻商家实施数据赋能策略,帮助平台与商家实现价值共创。本文考虑具有竞争关系的两个商家入驻同一电商平台,平台向商家有偿提供数据赋能服务,运用Hotelling模型刻画市场需求,构建电商平台与竞争性商家间的博弈模型,讨论电商平台数据赋能策略的实施方案,分析两个商家对数据赋能服务选择的博弈均衡,最后通过数值算例对结论进行验证。研究表明:电商平台数据赋能服务的收费标准影响竞争性商家是否接受数据赋能的博弈均衡,电商平台应根据不同条件决策是否实施数据赋能策略,在不同实施条件下制定相应的最佳收费标准及最优投资力度。本文为平台型企业大数据实施策略和入驻商家的运营决策提供理论参考。

关键词：电商平台数据赋能竞争性商家 Hotelling模型

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