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具有BCC或FCC晶体结构的固溶体高熵合金设计

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材料工程 2024年第1期52卷 16-26页

作者： hORBAN v.F. 乌克兰国家科学院弗兰采维奇材料问题研究所乌克兰基辅03680

高熵合金最初报道于21世纪初期,该类合金具有较高的混合熵值,使其具有优异的热稳定性;较大的晶格畸变,产生了强烈固溶强化效果;较大的负焓值导致在晶粒内部形成团簇结构,有效阻碍了位错运动,进一步提高了合金强度。高熵合金独有的这些特... 详细信息

高熵合金最初报道于21世纪初期,该类合金具有较高的混合熵值,使其具有优异的热稳定性;较大的晶格畸变,产生了强烈固溶强化效果;较大的负焓值导致在晶粒内部形成团簇结构,有效阻碍了位错运动,进一步提高了合金强度。高熵合金独有的这些特性,使其在低温和高温条件下均有望表现出优异的物理性能和力学性能,引起了广泛的关注,研究报道呈爆发性增长。本文根据已有的BCC和FCC结构高熵合金物理-力学性能数据,分析了电子浓度、晶格常数、原子错配度、混合焓、硬度、弹性模量和归一化硬度等参数之间的关系,提出了BCC和FCC晶体结构的高熵合金弹性模量和硬度的经验计算公式,在此基础之上,综合考虑合金密度、塑性和服役工况等条件,提出了BCC和FCC结构的高熵合金成分设计方法。最后指出高熵合金的持久性能、大尺寸铸锭的成分和性能均匀性以及大尺寸合金锭的制备是高熵合金工程应用需解决的关键问题。

关键词：高熵合金电子浓度晶格常数晶格畸变混合焓硬度弹性模量归一化硬度

The immune response to SARS-Cov-2 in people with hIv

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Cellular & Molecular Immunology 2024年第2期21卷 184-196页

作者： Maxine A.höft Wendy A.Burgers Catherine Riou Institute of Infectious Disease and Molecular Medicine University of Cape TownCape TownSouth Africa Division of Medical virology Department of PathologyUniversity of Cape TownCape TownSouth Africa Wellcome Centre for Infectious Diseases Research in Africa University of Cape TownCape TownSouth Africa

This review examines the intersection of the hIv and SARS-Cov-2 pandemics.People with hIv(PWh)are a heterogeneous group that differ in their degree of immune suppression,immune reconstitution,and viral control.While COvID-19 in those with wellcontrolled hIv infection poses no greater risk than that for hIv-uninfected individuals,people with advanced hIv disease are more vulnerable to poor COvID-19 outcomes.COvID-19 vaccines are effective and well tolerated in the majority of PWh,though reduced vaccine efficacy,breakthrough infections and faster waning of vaccine effectiveness have been demonstrated in PWh.This is likely a result of suboptimal humoral and cellular immune responses after vaccination.People with advanced hIv may also experience prolonged infection that may give rise to new epidemiologically significant variants,but initiation or resumption of antiretroviral therapy(ART)can effectively clear persistent infection.COvID-19 vaccine guidelines reflect these increased risks and recommend prioritization for vaccination and additional booster doses for PWh who are moderately to severely immunocompromised.We recommend continued research and monitoring of PWh with SARS-Cov-2 infection,especially in areas with a high hIv burden.

关键词： SARS-Cov-2 hIv Immune dysfunction vaccine efficacy Prolonged infection Immunogenicity

ion acceleration;quantum electrodynamic effects

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high Power Laser Science and Engineering 2024年第1期12卷 60-73页

作者： Shikha Bhadoria Mattias Marklund Christoph h.Keitel Max-Planck-Institut für Kernphysik HeidelbergGermany Department of Physics University of GothenburgGöteborgSweden

The impact of radiation reaction and Breit±Wheeler pair production on the acceleration of fully ionized carbon ions driven by an intense linearly polarized laser pulse has been investigated in the ultra-relativistic transparency regime.Against initial expectations, the radiation reaction and pair production at ultra-high laser intensities are found to enhance the energy gained by the ions. The electrons lose most of their transverse momentum, and the additionally produced pair plasma of Breit±Wheeler electrons and positrons co-streams in the forward direction as opposed to the existing electrons streaming at an angle above zero degree. We discuss how these observations could be explained by the changes in the phase velocity of the Buneman instability, which is known to aid ion acceleration in the breakout afterburner regime, by tapping the free energy in the relative electron and ion streams. We present evidence that these non-classical effects can further improve the highest carbon ion energies in this transparency regime.

关键词： ion acceleration quantum electrodynamic effects

Ranking environmental and edaphic attributes driving soil microbial community structure and activity with special attention to spatial and temporal scales

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mLife 2024年第1期3卷 21-41页

作者： vadakattu v.S.R.Gupta James M.Tiedje CSIRO Agriculture&Food UrrbraeSouth AustraliaAustralia Centre for Microbial Ecology Michigan State UniversityEast LansingMichiganUSA

The incredibly complex soil microbial communities at small scales make their analysis and identification of reasons for the observed structures challenging.Microbial community structure is mainly a result of the inoculum(dispersal),the selective advantages of those organisms under the habitat-based environmental attributes,and the ability of those colonizers to sustain themselves over time.Since soil is protective,and its microbial inhabitants have long adapted to varied soil conditions,significant portions of the soil microbial community structure are likely stable.hence,a substantial portion of the community will not correlate to often measured soil attributes.We suggest that the drivers be ranked on the basis of their importance to the fundamental needs of the microbes:(i)those that supply energy,i.e.,organic carbon and electron acceptors;(i)environmental effectors or stressors,i.e.,ph,salt,drought,and toxic chemicals;(ii)macro-organism associations,i.e.,plants and their seasonality,animals and their fecal matter,and soil fauna;and(iv)nutrients,in order,N,P,and probably of lesser importance,other micronutrients,and metals.The relevance of drivers also varies with spatial and time scales,for example,aggregate to field to regional,and persistent to dynamic populations to transcripts,and with the extent of phylogenetic difference,hence phenotypic differences in organismal groups.We present a summary matrix to provide guidance on which drivers are important for particular studies,with special emphasis on a wide range of spatial and temporal scales,and illustrate this with genomic and population(rRNA gene)data from selected studies.

关键词： abundance community structure diversity functional microbiome microorganisms

Why lowland riparian trees are difficult to use for streamflow reconstruction

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Journal of Forestry Research 2024年第3期35卷 219-230页

作者： Xiaomei Peng Shengchun Xiao Bao Yang Quanyan Tian vladimir v.Shishov Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000People's Republic of China School of Geography and Ocean Science Nanjing UniversityNanjing 210023People's Republic of China Institute of Fundamental Biology and Biotechnology Siberian Federal UniversityKrasnoyarskRussia 660041

Existing streamflow reconstructions based on tree-ring analysis mostly rely on species from upland,mainly montane areas,while lowland species(generally plain)areas are rarely used.This limits the understanding of streamflow change history in the lowlands,which is an important basis for water resource management.This study focused on Populus euphratica stands located along the main stream,eastern and western tributaries in the lower reaches of the heihe River basin(hRb),in arid northwestern China.We investigated how streamflow regulation interferes with ripar-ian trees in lowlands when they used for streamflow recon-struction.Tree-ring width chronologies were developed and analyzed in conjunction with meteorological and hydrologic observation data.The results show streamflow regulation leads in sharp fluctuations in the streamflow allocation between the eastern tributaries and western tributaries.This resulted in instability of the correlation between streamflow at the two tributaries and at the Zhengyixia hydrologic station,with corresponding fluctuations in radial growth of poplar trees on the banks of the two tributaries and at the station.Streamflow regulation altered the natural patterns of seasonal streamflow below the station,changing the time window of poplar response.This study provides useful insight into tree-ring width based streamflow reconstruction in the lowlands.

关键词： Tree-ring width-Dendrochronology Populus euphratica The Ejina Oasis Streamflow

vitamin D and hypertension:Is there any significant relation?

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Chronic Diseases and Translational Medicine 2024年第2期10卷 156-158页

作者： Naga P.vakkalagadda Sri h.Narayana Gummadi S.Sree Lakshmi D.Bethineedi L.v.Simhachalam Kutikuppala Gnana D.Medarametla Department of General Medicine Guntur Medical CollegeGunturAndra PradeshIndia Department of General Medicine Narayana Medical College and HospitalNelloreAndhra PradeshIndia Department of General Medicine Andhra Medical CollegeVisakhapatnamAndhra PradeshIndia Department of General Surgery Dr NTR University of Health SciencesVijayawadaAndhra PradeshIndia Department of General Medicine Amma Multi-Speciality HospitalThorrurTelanganaIndia

Dear Editor,Around a billion individuals worldwide have hypertension.Of these,95%have essential hypertension,a type of undiagnosed hypertension.1 The regulation of blood pressure(BP)involves numerous signaling pathways.Among them,the Renin Angiotensin System is well known.All these pathways are regulated by modulation of renal salt handling and tone of vascular smooth muscle(vSM)tissue.Any of these mechanisms can become faulty and alter the resistance arteries’vSM tone,which can elevate BP.however,since the exact origin of Ph and its pathophysiology are unknown,less effective,and generic treatments are used.2 The fact that more than 50%of hypertension patients in the USA do not have their BP under good control serves as an illustration of this.Antihypertensive treatment resistance affects an additional 5 million people and is defined as the inability to regulate BP despite the use of at least three antihypertensive drugs in combination.

关键词： hypertension drugs treatment

Microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with different prestrain levels

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Journal of Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.h.Zhang h.Li Z.W.Yang X.Liu Q.F.Gu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of high-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SMA)is a promising material in the aerospace field due to its wide transformation hysteresis.The application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to recovery.Low-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of SMA components.however,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)SMA subjected to vari-ous prestrain levels are still unclear.To this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(M_(s)+30℃)were investigated.The results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.Whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,respectively.In stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb inclusions.In stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SIMvs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced martensite.More{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density of{114}austenite twins form in the specimen with a larger prestrain of 16%.With increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then decreases.Theε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%prestrain.The increase ofε_(re)^(T)can be attributed to the formation of new SIMvs,the further growth of existing SIMvs,and the recoverable(001)compound twins.While the decrease ofε_(re)^(T)is mainly associated with the irrecoverable strain by{20−1}martensite twins.The effect ofβ-Nb inclusions on the evolution of SIMvs i

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy Wide transformation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes

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Chinese Physics C 2024年第4期48卷 95-106页

作者： S.v.Sidorov A.S.Kornilova T.Yu.Tretyakova Faculty of Physics Lomonosov Moscow State UniversityMoscow 119991Russia Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State UniversityMoscow 119991Russia

The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this work.Tensor forces are considered within the framework of the hartree-Fock approach with the Skyrme interaction.The addition of a tensor component of interaction is shown to improve the description of the splittings between different single-particle states and decrease nucleon-nucleon pairing correlations in silicon and nickel nuclei.Special attention was directed toward the role of isovector tensor forces relevant to the interaction of like nucleons.

关键词： nuclear shell model tensor interaction silicon isotopes nickel isotopes

Observability Analysis of Integrated Electricity and heating Systems with Thermal Quasi-dynamics in Pipelines

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1145-1158页

作者： Zhigang Li Wenjian Zheng Junbo Zhao J.h.Zheng Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China Fuzhou Changle District Power Supply Company of State Grid Fujian Electric Power Co. Ltd.Fuzhou 350000China Department of Electrical and Computer Engineering University of ConnecticutStorrsCT 06269USA CSEE IEEE

Observability analysis(OA)is vital to obtaining the available input measurements of state estimation(SE)in an integrated electricity and heating system(IEhS).Considering the thermal quasi-dynamics in pipelines,the measurement equations in heating systems are dependent on the estimated results,leading to an interdependency between OA and SE.Conventional OA methods require measurement equations be known exactly before SE is performed,and they are not applicable to IEhSs.To bridge this gap,a scenario-based OA scheme for IEhSs is devised that yields reliable analysis results for a predefined set of time-delay scenarios to cope with this interdependency.As its core procedure,the observable state identification and observability restoration are formulated in terms of integer linear programming.Numerical tests are conducted to demonstrate the validity and superiority of the proposed formulation.

关键词： Integrated electricity and heating system measurement observability analysis state estimation thermal quasi-dynamics