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Ground response and failure mechanism of gob-side entry by roof cutting with hard main roof

Journal of Central South University 2024年第7期31卷 2488-2512页

作者： ZHU Heng-zhong XU lei WEN zhi-jie State Key Laboratory of Water Resource Protection and Utilization in Coal Mining Beijing 102209China State Key Laboratory of Strata Intelligent Control and Green Mining Co-founded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266590China School of Energy and Mining Engineering Shandong University of Science and TechnologyQingdao 266590China School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454003China School of Mining Guizhou UniversityGuiyang 550025China

This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensive field measurement program was conducted to determine entry deformation,roof fracture zone,and anchor bolt(cable)*** results indicate that GSERC deformation presents asymmetric *** maximum convergence near roof cutting side is 458 mm during the primary use process and 1120 mm during the secondary reuse *** entry deformation is closely associated with the primary development stage,primary use stage,and secondary reuse *** key block movement of roof cutting structure,a complex stress environment,and a mismatch in the supporting design scheme are the failure mechanism of GSERC.A controlling ideology for mining states,including regional and stage divisions,was *** dynamic and permanent support schemes have been implemented in the *** practice results indicate that the new support scheme can efficiently ensure long-term entry safety and could be a reliable approach for other engineering practices.

关键词： gob-side entry by roof cutting ground response failure mechanism following mining states control hard main roof

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Preparation and Structure-Property Regulation Mechanism of Reversible Thermochromic Polydiacetylene

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Chinese Journal of Polymer Science 2024年第8期42卷 1111-1121页

作者： zhi-Qing Ge Shuo Yan Zu-Xiong Pan Shan lei Xuan-zhi Mao Chu Zhao Mo-Zhen Wang Xue-Wu Ge Key Laboratory of Precision and Intelligent Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China Marshall Laboratory of Biomedical Engineering International Cancer CenterLaboratory of Evolutionary Theranostics(LET)School of Biomedical EngineeringShenzhen University Medical SchoolShenzhen UniversityShenzhen 518055China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

The thermochromic mechanism and the structure-property regulation principle of reversible thermochromic polydiacetylene(PDA)materials have always been a challenging *** this work,a series of diacetylene monomers(m-PCDA)containing phenyl and amide or carboxyl groups were synthesized from 10,12-pentacosadiynoic acid(PCDA)through the esterification or amidation *** effects of the number and the distribution of the functional groups in m-PCDA molecules on their solid-state polymerization capability,and the thermochromic mechanism of their corresponding polymers(m-PDA)were investigated and discussed in *** results show that the m-PCDA monomers containing both benzene ring and groups that can form hydrogen bonding interactions have strong intermolecular interaction,and are easy to carry out the solid phase polymerization under 254-nm UV irradiation to obtain the corresponding new thermochromic m-PDA *** thermochromic behavior of m-PDA depends on its melting *** initial color-change temperature(blue to red)is determined by the onset melting tem perature,and the temperature range in which reversible color recovery can be achieved by repeat heating-cooling treatment is determined by its melting *** to the proposed thermochromic mechanism of PDA,various new PDA materials with precise thermochromic temperatu res and reversible thermochromic temperature ra nges can be designed and synthesized through the appropriate introduction of benzene ring and groups that can form hydrogen bonding interactions into the molecular structure of linear diacetylene *** work provides a perspective to the precise molecular structure design and the property regulation of the reversible thermochromic PDA materials.

关键词： Polydiacetylene Thermochromism Hydrogen bonding Chemical modification

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Experimental and simulation research on hollow AZ31 magnesium alloy three-channel joint by hot extrusion forming with sand mandrel

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Journal of Magnesium and Alloys 2024年第1期12卷 98-109页

作者： Shi Shengnan Wang Hongyu Teng Fei Jiang lei Sun Juncai Sun jie Zhang Shunhu Transportation Engineering College Dalian Maritime UniversityDalianLiaoning 106026China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyangLiaoning 110819China Shagang School of Iron and Steel Soochow UniversitySuzhouJiangsu 215021China

Magnesium alloy is one of the lightest metal structural *** weight is further reduced through the hollow ***,the hollow structure is easily damaged during *** order to maintain the hollow structure and to transfer the stresses during the high temperature deformation,the sand mandrel is *** this paper,the hollow AZ31 magnesium alloy three-channel joint is studied by hot extrusion *** as one of solid granule medium is used to fill the hollow magnesium *** extrusion temperatures are 230℃ and 300℃,*** process parameters(die angle,temperature,bottom thickness,sidewall thickness,edge-to-middle ratio in bottom,bottom shape)of the hollow magnesium alloy are analyzed based on the results of experiments and the finite element *** results are shown that the formability of the hollow magnesium alloy will be much better when the ratio of sidewall thickness to the bottom thickness is 1:*** when edge-to-middle ratio in bottom is about 1:1.5,a better forming product can be *** best bottom shape in these experiments will be convex based on the forming *** grain will be refined obviously after the *** the microstructures will be shown as *** these lines will be well agreement with the mold in the corner.

关键词： AZ31 magnesium alloy Three-channel joint Sand Experiments and the finite element Die angle

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Identification of Early Warning Signals of Infectious Diseases in Hospitals by Integrating Clinical Treatment and Disease Prevention

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Current Medical Science 2024年第2期44卷 273-280页

作者： lei ZHANG Min-ye LI Chen zhi Min ZHU Hui MA Sixth Medical Center Chinese PLA General HospitalBeijing100048China The Nursing Department Chinese PLA General HospitalBeijing 100853China

The global incidence of infectious diseases has increased in recent years,posing a significant threat to human *** typically serve as frontline institutions for detecting infectious ***,accurately identifying warning signals of infectious diseases in a timely manner,especially emerging infectious diseases,can be ***,there is a pressing need to integrate treatment and disease prevention data to conduct comprehensive analyses aimed at preventing and controlling infectious diseases within *** paper examines the role of medical data in the early identification of infectious diseases,explores early warning technologies for infectious disease recognition,and assesses monitoring and early warning mechanisms for infectious *** propose that hospitals adopt novel multidimensional early warning technologies to mine and analyze medical data from various systems,in compliance with national strategies to integrate clinical treatment and disease ***,hospitals should establish institution-specific,clinical-based early warning models for infectious diseases to actively monitor early signals and enhance preparedness for infectious disease prevention and control.

关键词： infectious disease disease prevention and control medical data warning signals

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Ecosystem service multifunctionality of mixed conifer-broad-leaved forests under climate change and forest management based on matrix growth modelling

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Forest Ecosystems 2024年第5期11卷 743-757页

作者： Xue Du Xiangdong lei Xiao He jie Lan Hong Guo Qigang Xu State Key Laboratory of Efficient Production of Forest Resources Key Laboratory of Forest Management and Growth ModellingNational Forestry and Grassland AdministrationInstitute of Forest Resource Information TechniquesChinese Academy of ForestryBeijing 100091China College of Forestry and Horticulture Hubei Minzu UniversityEnshi 445000China East China Academy of Inventory and Planning National Forestry and Grassland AdministrationHangzhou 310000China

Climate change and forest management are recognized as pivotal factors influencing forest ecosystem services and thus ***,the magnitude and the relative importance of climate change and forest management effects on the multifunctionality remain unclear,especially for natural mixed *** this study,our objective is to address this gap by utilizing simulations of climate-sensitive transition matrix growth models based on national forest inventory plot *** evaluated the effects of seven management scenarios(combinations of various cutting methods and intensities)on the future provision of ecosystem services and multifunctionality in mixed conifer-broad-leaved forests in northeastern China,under four climate scenarios(SSP1-2.6,SSP2-4.5,SSP5-8.5,and constant climate).Provisioning,regulating,cultural,and supporting services were described by timber production,carbon storage,carbon sequestration,tree species diversity,deadwood volume,and the number of large living *** findings indicated that timber production was significantly influenced by management scenarios,while tree species diversity,deadwood volume,and large living trees were impacted by both climate and management *** storage and sequestration were notably influenced by both management and the interaction of climate and *** findings emphasized the profound impact of forest management on ecosystem services,outweighing that of climate scenarios *** found no single management scenario maximized all six ecosystem service *** upper story thinning by 5%intensity with 5-year interval(UST5)management strategy emerged with the highest multifunctionality,surpassing the lowest values by more than 20%across all climate *** conclusion,our results underlined the potential of climate-sensitive transition matrix growth models as a decision support tool and provided recommendations for long-term strategies for multifunctional forest management

关键词： Multifunctional forest management Thinning Transition matrix growth model Carbon sink Timber production

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Resolving the geometric structure of trastuzumab by mobility capillary electrophoresis and native mass spectrometry

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Chinese Chemical Letters 2024年第3期35卷 221-225页

作者： Wenjing Zhang jie Hong lei Yang Zuqiang Xu Yu Xiang Wei Xu School of Life Science Beijing Institute of TechnologyBeijing 100081China

Available online Immunoglobulins G(IgGs)are Y-shaped globular proteins,however,their high flexibility and heterogeneity pose great challenges to their structure and conformation *** structure of IgG closely correlates to its biofunctions,such as the antibody escape of human immunodeficiency virus(HIV)could attribute to the distance mismatch between the ends of two Fab arms(antigen-binding sites)and envelope glycoprotein spikes on virion ***,we report the first use of mobility capillary electrophoresis(MCE)and native mass spectrometry(nMS)to resolve the internal geometric structure and conformation of an IgG(trastuzumab)in solution *** proteolysis,the ellipsoid dimensions of IgG and its subunits were measured by MCE-nMS *** was then reconstructed,in which the sizes and relative positions of these three subunits in three-dimensional space were *** was found that the two Fab arms have an angle of~102.1°and a distance of~11.0 nm between the two antigen-binding sites under native condition,and the Fc arm was tilted~16.0°towards one of the Fab *** was not on the plane of Fab-Fab,but has an angle of no larger than 103.1°.Under acidic environment(pH 3.0),each subunit of the IgG would unfold into larger dimensions,and the angles between these subunits also *** great potential for tumor imaging and therapy,the structure of F(ab')_(2)fragments was also measured and validated by molecular dynamic *** was found that the electrostatic force among these three subunits and steric hindrance stemming from Fc help maintaining the angle between two Fab arms.

关键词： Native mass spectrometry Mobility capillary electrophoresis Trastuzumab Protein structure Geometric structure

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General radical difluoromethylation using difluoroacetic anhydride via photoredox catalysis

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Science China Chemistry 2024年第8期67卷 2637-2646页

作者： Meng He Yankai Yang Heng Zhang zhipeng Guan zhi-Bing Dong Hong Yi Aiwen lei School of Chemistry and Environmental Engineering Wuhan Institute of TechnologyWuhan 430205China College of Chemistry and Molecular Sciences and Institute for Advanced Studies(IAS) Wuhan UniversityWuhan 430072China

CF_(2)H-containing molecules play pivotal roles in diverse fields from medicinal chemistry to materials science. However, the application of existing CF_(2)H reagents as a source of CF_(2)H radical is limited by their reactivity and preparation. Herein, we develop a simple and general visible-light-catalyzed radical difluoromethylation reaction of alkenes, dienes, and heteroaromatics using commercially available, easy-to-handle, and low-cost difluoroacetic anhydride as the CF_(2)H reagent. This scalable protocol enables the convenient synthesis of a range of CF_(2)H-containing compounds under mild conditions, exhibiting a broad substrate scope and functional group tolerance. Potential applications are further demonstrated by gram-scale synthesis, sunlight experiments, derivatization experiments as well as the synthesis of bioactive molecules.

关键词： radical difluoromethylation alkenes/dienes/heteroaromatics difluoroacetic anhydride photoredox

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Direct observation of shock-induced phase transformation in polycrystalline iron via in situ x-ray diffraction

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Chinese Physics B 2024年第10期33卷 337-342页

作者： Fan Zhang Jia-Qin Dong zhi-Yong Xie zhi-Yu He Hua Shu Rui-Rong Wang Jun Xiong Guo Jia zhi-Heng Fang Wei Wang Da-Wu Xiao An-Le lei jie Chen Xiu-Guang Huang Collaborative Innovation Center of IFSA(CICIFSA) School of Physics and AstronomyCenter for Ultrafast Science and TechnologyKey Laboratory for Laser Plasmas(Ministry of Education)Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Institute of Laser Plasma China Academy of Engineering PhysicsShanghai 201800China Institute of Materials China Academy of Engineering PhysicsMianyang 621700China

Phase transition of polycrystalline iron compressed along the Hugoniot is studied by combining laser-driven shock with in situ x-ray diffraction *** is suggested that polycrystalline iron changes from an initial body-centered cubic structure to a hexagonal close-packed structure with increasing pressure(i.e.,a phase transition fromαtoε).The relationship between density and pressure for polycrystalline iron obtained from the present experiments is found to be in good agreement with the gas-gun Hugoniot *** results show that experiments with samples at lower temperatures under static loading,such as in a diamond anvil cell,lead to higher densities measured than those found under dynamic *** means that extrapolating results of static experiments may not predict the dynamic responses of materials *** addition,neither the face-centered cubic structure seen in previous molecular-dynamics simulations or twophase coexistence are found within our experimental pressure range.

关键词： in situ x-ray diffraction phase transition polycrystalline iron

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Synergistic effect between Er-doped MoS_(2)nanosheets and interfacial Mo-N coupling phases for enhanced electrocatalytic hydrogen evolution

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Rare Metals 2024年第3期43卷 1301-1308页

作者： Nian-Peng Li lei Zhang Hua Zhang Fan-Fei Min lei Wang Sam Toan Xi-Jun Liu Guang-zhi Hu State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines School of Materials Science and EngineeringAnhui University of Science and TechnologyHuainan232001China Donghai Laboratory Zhoushan316021China Department of Chemical Engineering University of Minnesota-DuluthDuluthMN55812USA School of Ecology and Environmental Science Institute for Ecological Research and Pollution Control of Plateau LakesYunnan UniversityKunming650504China MOE Key Laboratory of New Processing Technology for Non-Ferrous Metals and Materials Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured MaterialsGuangxi UniversityNanning530004China

Hydrogen production via electrochemical water splitting is a promising and green *** one of the most representative transition metal sulfides layered materials,Molybdenum disulfide(MoS_(2))has immense potential for the hydrogen evolution reaction(HER).We successfully prepared a nitrogen-doped carbon(NC)in situ-grown erbium-doped MoS_(2)polyhedral structure(Er-MoS_(2)/NC)that incorporates an interfacial Mo-N coupling phase.

关键词： hydrogen interfacial coupling

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Influence of Heat-setting Temperature on the Microporous Structure and Properties of PP/HDPE Bilayer Microporous Membranes

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Chinese Journal of Polymer Science 2024年第8期42卷 1243-1252页

作者： jie Xie Yong-Shi Wu Jia-Yi Xie Rui-jie Xu Cai-Hong lei Sai-Nan Song Guang-Quan Li An-Ping Huang School of Materials and Energy Guangdong University of TechnologyGuangzhou 510006China Lanzhou Petrochemical Research Center Petrochemical Research InsititutePetroChinaLanzhou 730060China School of Chemistry and Civil Engineering Shaoguan CollegeShaoguan 512005China

Due to the mechanical stability of PP layer,the PP/HDPE double-layer microporous mem brane could be prepared at a higher heat-setting temperatu re than that of PE monolayer *** this work,the effects of heat-setting temperature on the pore structure and properties of PP/HDPE dou ble-layer membrane were *** the increase of heat-setting temperature from 120℃to 130℃,the length of connecting bridge crystal and crystallinity in the PE layer increase due to the melting of thin lamellae and the stability of connecting bridge structure during *** corresponding air permeability,po rosity,wetta bility of liquid electrolyte and mechanical property of the heat-set microporous membrane increase,exhibiting better electrochemical ***,when the heat-setting temperature is further increased to 140℃,higher than the melting point of PE resin,some pores are closed since the lamellae and connecting bridges melt and shrink during heat-setting,resulting in a decrease of air permeability and *** contrast,there is negligible change in the PP layer within the above heat-setting temperature *** study successfully builds the relationship between the stable pore structure and property of microporous membrane during heat-setting,which is helpful to guide the production of high-pe rformance PP/PE/PP lithium batteries separator.

关键词： PP/HDPE bilayer microporous membranes Heat-setting temperature SAXS

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