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Solid solution strategy modulated defects engineering of (Cr1-xVx)2AlC MAX phase toward superior electromagnetic wave absorption

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Rare Metals 2024年第7期43卷 3205-3219页

作者： Ji-Lin Gou yu-kai chang Shu Liu Peng-Hui Li Ping-Hao Cui Qian-Ku Hu Li-Bo Wang Xin Zhang Jun-kai Wang Qi-Xun Xia Ai-Guo Zhou School of Materials Science and Engineering Henan Polytechnic University Key Laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan University State Key Laboratory of Metastable Materials Science and Technology Yanshan University

Defects engineering is an effective strategy for manipulating electromagnetic parameters and enhancing electromagnetic wave（EMW） absorption ***,the relationship between them is not clear,especially in solid solution *** this work,a series of(Cr1-xVx)2AlC MAX phase solid solutions with layered structure were prepared via tuning the ratio of Cr and V to explore their EMW absorption *** experimental results indicated that the doping of V atoms at the M-site could effectively regulate its impedance matching and EMW absorption properties by introducing appropriate numbers of defects in the crystal,such as twin boundaries,dislocations and lattice *** them,if Cr:V=3:1,Cr1.5V0.5AlC,as radar absorption materials,could reach a strong reflection loss of-51.8 dB at the frequency of 12.8 GHz under an ultra-thin thickness of 1.3 *** reflection loss value could attain-10 dB in a wide frequency range of 2.7-18 GHz and thickness range of 1-5 *** addition,after high temperature and acid-alkali immersion treatment,this sample still had good EMW absorption capability,and the effective absorption bandwidth was enhanced from 2.3 to 2.6 GHz after concentrated acid immersion or 3.1 GHz after concentrated alkali *** work has great reference significance for the research and development of high-performance MAX-based EMW absorption materials in harsh environments.

关键词： MAX phases Solid solution Defects engineering Electromagnetic wave absorption Harsh environments

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Spin-orbit interaction induced Casimir-Lifshitz torque between two-dimensional electron gases

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 134-142页

作者： Jia-Nan Rong Liang Chen kai chang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China School of Physics Zhejiang UniversityHangzhou 310027China College of Materials Science and Opto-electronic Technology University of Chinese Academy of SciencesBeijing 100049China

We investigate theoretically the Casimir interaction between two parallel two-dimensional electron gases(2DEGs)with Rashba and Dresselhaus spin-orbit interactions(SOIs),based on the quantum field *** derive an analytical expression for the polarization tensor and obtain the solution to the motion equation of the electromagnetic(EM)*** calculate the CasimirLifshitz torque(CLT)between two parallel 2DEGs with Rashba and Dresselhaus SOIs,which can be tuned by changing the relative strength between two *** anisotropic Casimir energy between 2DEGs caused by the interplay between the SOIs of 2DEGs offers a new origin of CLT and a new type of optoelectronic device.

关键词： Casimir torque two-dimensional electron gas spin-orbit interaction

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A study on the application of diffuse axonal multi-axis general evaluation for braininjury assessment in small overlap barrier crash test

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Chinese Journal of Traumatology 2024年第4期27卷 200-210页

作者： Zhi Fu Yi chang Tao Xiong Wen-kai Gao Kui Li yu Liu China Automotive Engineering Research Institute Co. Ltd.Chongqing401122China Chongqing University of Technology Chongqing400054China Chongqing Key Laboratory of Vehicle Crash/Bio-Impact and Traffic Safety Chongqing400042China College of Medical Informatics Chongqing Medical UniversityChongqing400016China

Purpose:Head injury criterion(HIC)companied by a rotation-based metric was widely believed to behelpful for head injury prediction in road traffic ***,the Euro-New Car AssessmentProgram utilized a newly developed metric called diffuse axonal multi-axis general evaluation(DAMAGE)to explain test device for human occupant restraint(THOR)head injury,which demonstratedexcellent ability in capturing concussions and diffuse axonal ***,there is still a lack ofcomprehensive understanding regarding the effectiveness of using DAMAGE for Hybrid III 50thpercentile male dummy(H50th)head injury *** objective of this study is to determinewhether the DAMAGE could capture the risk of H50th brain injury during small overlap barrier ***:To achieve this objective,a total of 24 vehicle crash loading curves were collected as input datafor the multi-body *** commercially available mathematical dynamic models,namelyH50th and THOR,were utilized to investigate the differences in head injury ***,adecision method known as simple additive weighting was employed to establish a comprehensive braininjury metric by incorporating the weighted HIC and either DAMAGE or brain injury ***,35 sets of vehicle crash test data were used to analyze these brain injury ***:The rotational displacement of the THOR head is significantly greater than that of the *** maximum linear and rotational head accelerations experienced by H50th and THOR modelswere(544.6±341.7)m/s^(2),(2468.2±1309.4)rad/s^(2) and(715.2±332.8)m/s^(2),(3778.7±1660.6)rad/s^(2),*** the same loading condition during small overlap barrier(SOB)tests,THOR exhibits ahigher risk of head injury compared to the H50th *** was observed that the overall head injuryresponse during the small overlap left test condition is greater than that during the small overlap ***,an equation was formulated to establis

关键词： Diffuse axonal multi-axis general evaluation Head injury criterion Head injury assessment Small overlap barrier Biomechanical response

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Amplification effect of intra-seasonal variability of soil moisture on heat extremes over Eurasia

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Advances in Climate change Research 2024年第1期15卷 1-8页

作者： Yi-Nuo WANG Zhi-Yan ZUO Liang QIAO kai-Wen ZHANG Mei-yu chang Dong XIAO Zou-Xing LIN Huan WANG Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China CMA-FDU Joint Laboratory of Marine Meteorology Shanghai 200438China Key Laboratory of Cites Mitigation and Adaptation to Climate change in Shanghai China Meteorological AdministrationShanghai 200030China Collaborative Innovation Centeron Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 211800China Shanghai Frontiers Science Center of Atmosphere-Ocean Interaction Shanghai 200123China College of Geography and Resources Science Sichuan Normal UniversityChengdu 610101China National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary Shanghai 202183China Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081China

Drying soil has been conducive to a high frequency of extreme high-temperature events over many regions worldwide in recent ***,changes in the intraseasonal variability of soil moisture can also influence the likelihood of extremely high *** previous investigators have examined the association between extremely high temperatures and large-scale atmospheric circulation variability,the role of land-atmosphere coupling dominated by soil moisture variability in extremely high temperatures,particularly over the Eurasian continent,is not well *** this study,on the basis of the Land Surface,Snow,and Soil Moisture Model Intercomparison Project,we found that land-atmosphere feedback amplified the variability of soil moisture in most regions of Eurasia during summer from 1980 to *** amplification of soil moisture variability is closely correlated with more intensive intraseasonal variability of surface air temperature and more frequent occurrences of extreme high-temperature events,particularly in Europe,Siberia,Northeast Asia,and the Indochina *** correlation implies that increasing the intraseasonal variability of soil moisture results in a high likelihood of heat extremes during summer in most parts of Eurasia except Asian desert *** the intraseasonal timescale,the land-atmosphere coupling increases the variability of surface sensible heat flux and net long-wave radiation heating the atmosphere by intensifying the soil moisture variability,thus amplifying the variability of surface air temperature and enhancing the extreme high-temperature *** finding demonstrates the importance of changes in intraseasonal soil moisture variability for the increasing likelihood of heat extremes in summer.

关键词： Soil moisture Intraseasonal variability Land-atmosphere coupling Heat extremes

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Ion and electron motions in the outer electron diffusion region of collisionless magnetic reconnection

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Earth and Planetary Physics 2024年第3期8卷 472-478页

作者： Cong chang QuanMing Lu San Lu kai Huang RongSheng Wang Deep Space Exploration Laboratory School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Chinese Academy of Sciences(CAS)Center for Excellence in Comparative Planetology CAS Key Laboratory of Geospace EnvironmentHefei 230026China Collaborative Innovation Center of Astronautical Science and Technology Harbin 150001China

Two-dimensional particle-in-cell simulations are performed to study the coupling between ion and electron motions in collisionless magnetic *** electron diffusion region(EDR),where the electron motions are demagnetized,is found to have a two-layer structure:an inner EDR near the reconnection site and an outer EDR that is elongated to nearly 10 ion inertial lengths in the outflow *** the inner EDR,the speed of the electron outflow increases when the electrons move away from the X *** the outer EDR,the speed of the electron outflow first increases and then decreases until the electrons reach the boundary of the outer *** the boundary of the outer EDR,the magnetic field piles up and forms a depolarization *** the perspective of the fluid,a force analysis on the formation of electron and ion outflows has also been *** the X line,the electrons are accelerated by the reconnection electric field in the out-of-plane *** the electrons move away from the X line,we find that the Lorentz force converts the direction of the accelerated electrons to the x direction,forming an electron *** electric field forces and electron gradient forces tend to drag the electron *** acceleration along the x direction is caused by the Lorentz force,whereas the pressure gradient force tends to decelerate the ion *** these two terms are important,their effects on ions are almost *** Hall electric field force does positive work on ions and is not *** ions are continuously accelerated,and the ion and electron outflow velocities are almost the same near the depolarization front.

关键词： collisionless magnetic reconnection electron diffusion region force analysis particle-in-cell simulation

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Simultaneously enhancing erosion and compression resistance:designing AlCoCrFeNi high-entropy alloy strengthened Ag-based contacts

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Rare Metals 2024年第9期43卷 4476-4492页

作者： Xiao-Yang Xue Zhe Wang Hui-Ling Nie Zhao yuan Jun Wang chang-Hu Xu kai Wen Cong-Hao yu School of Materials Science and Engineering Xi’an Polytechnic University School of Physics Xi’an Jiaotong University Key Laboratory of Pulsed Power Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology

Designing microstructures and unveiling dynamic erosion mechanisms remain important challenges for Ag-based contacts. To simultaneously enhance erosion and compression resistance, an Al Co Cr Fe Ni high-entropy alloy(HEA) is introduced into Ag-based materials to fabricate novel Ag-HEA contacts with island-and skeletonrestricted microstructures. The arc erosion experimental results reveal that the skeleton-restricted HEA microstructure is the key factor in reducing the hill and crater morphologies of the contact surface, effectively delaying material transfer between the movable and stationary contacts. The molten bridge evolution and compressive deformation behavior of Ag-HEA contacts with various microstructures are investigated using molecular dynamics(MD) simulations. MD results indicate that the constraint of Ag atom diffusion in the molten pool and the involvement of HEA atoms in the molten bridge are the primary mechanisms for improving erosion resistance. The skeleton-restricted HEA microstructure reduces the total energy and structural stability of the molten bridge system and promotes its fracture and disintegration. Moreover, the synergistic effect of the twin and Lomerz–Cottrell lock structures can hinder dislocation glide, generating dispersed and small-area stacking faults in the Ag matrix and mitigating the concentration of shear strains. Thus, the skeleton-restricted HEA microstructure contributes positively to compression resistance. This study presents a novel approach to designing Ag-based contacts.

关键词： Arc erosion Electrical contact materials High entropy alloys Microstructures Molecular dynamics

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Exercise,cognitive function, and the brain:Advancing our understanding of complex relationships

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Journal of Sport and Health Science 2019年第4期8卷 299-300页

作者： Jennifer L.Etnier yu-kai chang Department of Kinesiology University of North Carolina at GreensboroGreensboroNC27413USA Department of Physical Education National Taiwan Normal UniversityTaipei 10610TaiwanChina

In recent years,scientists have shown a growing interest in the relationship between exercise,cognitive function,and the *** growing body of evidence supporting positive relationships is evidenced by the first mention of the beneficial effects of exercise on cognitive function appearing in the 9th edition of the American College of Sports Medicine's guidelines published in 2014.1 The strength of this evidence is further confirmed by recommendations relative to the benefits of exercise for cognitive performance and mental health being included in the 2nd edition of the Physical Activity Guidelines for Americans,a landmark policy statement released by the *** of Health and Human Services.

关键词： complex relationships first mention beneficial effects

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Differences and Correlations of Morphological and Hemodynamic Parameters between Anterior Circulation Bifurcation and Side-wall Aneurysms

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Current Medical Science 2024年第2期44卷 391-398页

作者： kai-kai GUO chang-ya LIU Gao-hui LI Jian-ping XIANG Xiao-chang LENG Yi-ke CAI Xue-bin HU Department of Neurosurgery Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430022China Department of Emergency Longhua HospitalShanghai University of Traditional Chinese MedicineShanghai 200032China Artery Flow Technology Co. Ltd.Hangzhou 310051China

Objective:The objective of this research was to explore the difference and correlation of the morphological and hemodynamic features between sidewall and bifurcation aneurysms in anterior circulation arteries,utilizing computational fluid dynamics as a tool for ***:In line with the designated inclusion criteria,this study covered 160 aneurysms identified in 131 patients who received treatment at Union Hospital of Tongji Medical College,Huazhong University of Science and Technology,China,from January 2021 to September *** follow-up digital subtraction angiography(DSA)data,these cases were classified into two distinct groups:the sidewall aneurysm group and the bifurcation aneurysm *** and hemodynamic parameters in the immediate preoperative period were meticulously calculated and examined in both groups using a three-dimensional DSA reconstruction ***:No significant differences were found in the morphological or hemodynamic parameters of bifurcation aneurysms at varied locations within the anterior ***,pronounced differences were identified between sidewall and bifurcation aneurysms in terms of morphological parameters such as the diameter of the parent vessel(Dvessel),inflow angle(θF),and size ratio(SR),as well as the hemodynamic parameter of inflow concentration index(ICI)(P0.5,P<0.001).Conclusions:The significant differences in certain morphological and hemodynamic parameters between sidewall and bifurcation aneurysms emphasize the importance to contemplate variances in threshold values for these parameters when evaluating the risk of rupture in anterior circulation *** it is a bifurcation or sidewall aneurysm,these disparities should be *** morphological parameter SR has the potential to be a val

关键词： sidewall bifurcation unruptured aneurysms computational fluid dynamics

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Major Clinical Features and Epidemic Characteristics of Erosive Vulvar Lichen Planus:A Retrospective Analysis

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International Journal of Dermatology and Venereology 2024年第2期7卷 94-98页

作者： Ya-Kun Shao kai-Lyu Sun Min Yang Wan Liu yu Fu Jian-Min chang Department of Dermatology Beijing HospitalNational Center of GerontologyInstitute of Geriatric MedicineChinese Academy of Medical SciencesBeijing 100730China

Objective:Vulvar lichen planus(VLP),especially erosive VLP(EVLP),seriously affects women’s physiological function and quality of life.A retrospective analysis of erosive vulvar lichen planus(EVLP)was performed to raise awareness on this chronic,deforming,and painful vulvar ***:This observational retrospective study involved 40 patients with EVLP among 1,368 patients with vulvar disease from 2017 to *** patients’vulvar clinical features and extravulvar mucosal involvement were *** patients’pain and quality of life were evaluated with the numeric rating scale and the Dermatology Life Quality Index(DLQI),*** characteristics were reported using frequencies and proportions for categorical *** variables are expressed as mean±standard *** association between NRS score for pain and DLQI score was analyzed by Pearson’s correlation ***:EVLP accounted for 2.9%(40/1,368)of all cases of vulvar disease,and the median age at onset was 42 *** mostly occurred on the labia minora and ***(20/40)of the patients had extravulvar mucosal ***(42.5%)patients had oral lichen planus,and seven(17.5%)patients were diagnosed with vulvovaginal-gingival *** numeric rating scale score showed that 47.5%(19/40)of patients experienced mild pain,whereas 12.5%(5/40)described the pain as ***-one patients(77.5%,31/40)had dyspareunia,and nine patients had aggravated pain after sexual *** mean DLQI score was 9.1±6.0,with 37.5%(15/40)of patients indicating that EVLP had severely affected their *** numeric rating scale score for pain was significantly correlated with the DLQI score(P=0.007).Conclusion:EVLP can affect the quality of women’s lives and cause severe deformations and painful architectural *** description of the characteristics of EVLP in this report will benefit the diagnosis and early treatment of this disease.

关键词： erosive vulvar lichen planus multiple mucosal involvement pain assessment quality of life Dermatology Life Quality Index numeric rating scale

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Enhancement of low-temperature toughness of Fe-Mn-C-Al alloy by rare earth Ce-modified inclusions

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Journal of Iron and Steel Research(International) 2024年第1期31卷 157-173页

作者： Guang-kai Yang chang-ling Zhuang Yi-zhuang Li Chen Hu Shao-bo Li College of Materials and Metallurgy Guizhou UniversityGuiyang550025GuizhouChina Department of Mechanical Engineering University of Hong KongHong Kong999077China The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819LiaoningChina State Key Laboratory of Public Big Data Guizhou UniversityGuiyang550025GuizhouChina

Fe-Mn-C-Al alloys have been recognized as promising materials for certain low-temperature applications due to their exceptional mechanical properties and ***,their limited low-temperature toughness restricts their large-scale applications in specific *** influence of trace amounts of rare earth cerium(Ce)on the low-temperature toughness of Fe-18Mn-0.6C-1.8Al alloys was *** addition of Ce effectively alters the inclu-sions in the alloy,transforming large-sized irregular inclusions into fine ellipsoidal rare earth *** leads to a significant reduction in both the proportion and average size of the inclusions,resulting in their effective dispersion throughout the matrix and improved cryogenic *** presence of Ce-containing inclusions within the matrix reduces stress concentration,thereby inhibiting microcrack formation and improving impact absorption ***-cally,the addition of rare earth Ce alters the fracture behavior of the material at room temperature and low temperature,changing from brittle cleavage fracture to a more ductile failure *** impact toughness of the Fe-Mn-C-Al alloy is significantly improved by the addition of 0.0048 wt.%Ce,particularly at-196℃where the impact toughness reaches 103.6 J/cm^(2),representing an impressive improvement of 87.3%.

关键词： Fe-Mn-C-Al alloy Rare earth Low-temperature toughness Inclusion Fracture

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