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A wide hybrid zone mediated by Precipitation contributed to confused geographical structure of Scutiger boulengeri

Zoological Research 2023年第1期44卷 3-19页

作者： Xiu-Qin Lin Yin-Meng Hou Wei-Zhao Yang Sheng-Chao Shi Pu-Yang Zheng Chung-Kun Shih Jian-Ping Jiang Feng Xie CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province Chengdu Institute of BiologyChinese Academy of SciencesChengduSichuan 610041China University of Chinese Academy of Sciences Beijing 100049China College of Life Sciences Capital Normal UniversityBeijing 100048China Department of Paleobiology National Museum of Natural HistorySmithsonian InstitutionWashington DC 20013–7012USA Mangkang Biodiversity and Ecological Station Xizang Ecological Safety Monitor NetworkChangduXizang 854500China

Confused geographical structure of a population and mitonuclear discordance are shaped by a combination of rapid changes in population demographics and shifts in ecology.In this study,we generated a time-calibrated phylogeny of Scutiger boulengeri,an endemic Xizang alpine toad occurring in mountain streams on the Qinghai-Xizang(Tibet)Plateau(QTP).Based on three mitochondrial DNA(mt DNA)genes,eight clades were assigned to three deeply divergent lineages.Analysis of nuclear DNA(nu DNA)genes revealed three distinct clusters without geographic structure,indicating significantly high rates of gene flow.Coalescent theory framework analysis(approximate Bayesian computation model DIYABC and Migrate-N)suggested that divergence of the main intraspecific clusters was the result of hybridization after secondary contact in the Holocene around 0.59 million years ago(Ma).The ratio of mt DNA FST(fixation index)to nu DNA FST was 2.3,thus failing to show male-biased dispersal.Geographic cline analysis showed that a wide hybrid zone was initially established in southwestern China,without significant reproductive isolation but with strong introgression in S.boulengeri,suggesting high hybrid fitness.Furthermore,mt DNA genes exhibited isolation by distance(IBD)while nu DNA genes exhibited significant isolation by environment(IBE).Results suggested that mitonuclear discordance may have initially been caused by geographic isolation,followed by Precipitation-mediated hybridization,producing a wide hybrid zone and geographic structure confusion of nu DNA genes in S.boulengeri.This study indicated that complicated historical processes may have led to specific genetic patterns,with a specific climate factor facilitating gene flow in the system.

关键词： Hybrid zone Mitonuclear discordance Precipitation Genetic structure Secondary contact

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Improvement of cloud microphysical parameterization and its advantages in simulating Precipitation along the Sichuan-Xizang Railway

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Science China Earth Sciences 2024年第3期67卷 856-873页

作者： Xiaoqi XU Zhiwei HENG Yueqing LI Shunjiu WANG Jian LI Yuan WANG Jinghua CHEN Peiwen ZHANG Chunsong LU China Meteorological Administration Transportation Meteorology Key Laboratory Nanjing Joint Institute for Atmospheric SciencesNanjing 210041China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province Institute of Plateau MeteorologyCMAChengdu 610072China State Key Laboratory of Disaster Weather Chinese Academy of Meteorological SciencesBeijing 100081China Collaborative Innovation Center for Western Ecological Safety Lanzhou UniversityLanzhou 730000China China Meteorological Administration Aerosol-Cloud and Precipitation Key Laboratory and Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science and TechnologyNanjing 210044China

The Sichuan-Xizang Railway is an important part of the railway network in China, and geological disasters, such as mountain floods and landslides, frequently occur in this region. Precipitation is an important cause of these disasters;therefore,accurate simulation of the Precipitation in this region is highly important. In this study, the descriptions for uncertain processes in the cloud microphysics scheme are improved;these processes include cloud droplet activation, cloud-rain autoconversion, rain accretion by cloud droplets, and the entrainment-mixing process. In the default scheme, the cloud water content of different sizes corresponds to the same cloud droplet concentration, which is inconsistent with the actual content;this results in excessive cloud droplet size, unreasonable related conversion rates of microphysical process(such as cloud-rain autoconversion), and an overestimation of Precipitation. Our new scheme overcomes the problem of excessive cloud droplet size. The processes of cloudrain autoconversion and rain accretion by cloud droplets are similar to the stochastic collection equation, and the mixing mechanism of cloud droplets is more consistent with that occurred during the actual physical process in the cloud. Based on the new and old schemes, multiple Precipitation processes in the flood season of 2021 along the Sichuan-Xizang Railway are simulated, and the results are evaluated using ground observations and satellite data. Compared to the default scheme, the new scheme is more suitable for the simulation of cloud physics, reducing the simulation deviation of the liquid water path and droplet radius from 2 times to less than 1 time and significantly alleviating the overestimation of Precipitation intensity and range of Precipitation center. The average root-mean-square error is reduced by 22%. Our results can provide a scientific reference for improving Precipitation forecasting and disaster prevention in this region.

关键词： The Sichuan-Xizang Railway Cloud microphysics Precipitation Model improvement

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Simultaneously enhancing the strength and ductility of as-extruded AlN/AZ91 composites via nano-Precipitation and pyramidal slip

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Journal of Materials Science & Technology 2024年第5期172卷 240-254页

作者： Bin Zhang Yunxia Sun Tuo Liang Yunzhen Li Tian Li Jingchao Wang Ruiru Cai Changlin Yang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

Age hardening is often used to optimize the mechanical properties of as-deformed Mg-based materials in industry,whereas the improvement of strength is usually accompanied by the significant loss of ductility,which hinders the application of Mg-based materials in structural components.In the present work,high strength-ductility synergy(the yield strength of 263±9 MPa,ultimate tensile strength of 398±7 MPa and elongation to fracture of 34%±1%)was realized in as-extruded AlN/AZ91 composites after optimiz-ing aging processes.Microstructural characterization shows that AlN particles induced a large number of geometrically necessary dislocations around the AlN/Mg interface during extrusion,which decreased the nucleation barrier and provided more heterogeneous nucleation sites forγ-Mg 17 Al 12 continuous precipi-tation.Meanwhile,95%of residual dislocations in as-extruded AlN/AZ91 composites were annihilated dur-ing peak-aging,suppressing the growth and coarsening of continuous precipitates.Therefore,high density of nano-sizedγ-Mg 17 Al 12 continuous precipitates was produced in as-extruded AlN/AZ91 composites af-ter peak-aging.During tension,gliding dislocations bypassed sphericalγ-Mg 17 Al 12 nano-precipitates by Orowan looping rather than cutting mechanism,which induced a strong block on dislocation motion.So high yield strength was mainly attributed to the high density of non-shearableγ-Mg 17 Al 12 nano-precipitates with spherical morphology,which was different from other Mg-Al-based systems.The results of texture evolution and slip trace analysis demonstrated that the suppression of extension twinning and less basal slip was due to the enhanced activity of pyramidalc+aslip in as-extruded AlN/AZ91 com-posites after peak-aging during the room temperature tension,meanwhile,the dislocation density of as-extruded AlN/AZ91 composites was significantly decreased during peak-aging,then higher elongation to fracture was achieved.

关键词： Magnesium matrix composites Mechanical properties Precipitation Deformation mechanisms Non-basal slip

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Variable Precipitation behaviors of Laves phases in an ultralight Mg-Li-Zn alloy

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镁合金学报(英文) 2023年第6期11卷 2018-2026页

作者： Weixin Lou Hongbo Xie Xiaobo Zhao Junyuan Bai Hehang Zhang Yi Wang Xinze Li Hucheng Pan Yuping Ren Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Research Center for Metal Wires Northeastern UniversityShenyang 110819China

Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane Precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a specific habit plane owing to the constraint of free-energy minimization of the system.Herein,in an aged ultralight Mg-Li-Zn alloy,we confirmed that the precipitates dominated by C15 Laves structure could form in a variety of habit planes,to generate three forms of strengthening-phases,i.e.,precipitate-rod,precipitate-lath,and precipitate-plate.Among which,the precipitate-plates are on basal plane as usually but precipitate-rods/laths are on non-basal plane,and such non-basal precipitates would transform into the basal(Mg,Li)Zn_(2)Laves structure with prolonged aging.These findings are interesting to understand the Precipitation behaviors of multi-domain Laves structures in hexagonal close-packed crystals,and expected to provide a guidance for designing ultralight high-strength Mg-Li based alloys via Precipitation hardening on the non-basal planes.

关键词： Laves phase Precipitation Habit plane Orientation Magnesium alloys

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Tailoring coercive field in rare earth giant magnetostrictive materials byα-Fe Precipitation

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Rare Metals 2023年第2期42卷 606-613页

作者： Fang-Xian Zhang Peng-Qiang Hu Zheng-Ming Zhang Jian-Hu Gong Dun-Hui Wang Division of Microelectronic Materials and Devices Hangzhou Dianzi UniversityHangzhou310018China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing210093China

Rare earth giant magnetostrictive materials(GMMs)Tb_(1-x)Dy_(x)Fe_(2±δ)(Tb-Dy-Fe)have been successfully employed in many microelectromechanical devices due to their excellent magnetostrictive properties at room temperature.However,Tb-Dy-Fe still shows a relatively large coercivity with high hysteresis,which inevitably limits its application range.Herein,micromagnetic simulations are performed to investigate the size effect of precipitated phase(α-Fe)on coercivity in Tb-Dy-Fe.Simulation results demonstrate that the coercivity is reduced from 31.46 to 12.48 mT with increasing the size ofα-Fe from 4 to 50 nm in Tb-Dy-Fe since the precipitated phase ofα-Fe can act as a magnetization reversal nucleus.This decreasing trend of coercivity can be well fitted with an inverse square relationship,which agrees well with the nucleation theory.Our study highlights that the coercivity of Tb-Dy-Fe can be tailored by tuning the size ofα-Fe Precipitation.

关键词： Giant magnetostrictive material(GMM) Precipitation Coercivity Micromagnetic simulation

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Suppression of discontinuous Precipitation and strength improvement by Sc doping in Cu-6 wt%Ag alloys

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Journal of Materials Science & Technology 2023年第4期135卷 80-96页

作者： Bailing An Rongmei Niu Yan Xin William LStarch Zhaolong Xiang Yifeng Su Robert E.Goddard Jun Lu Theo M.Siegrist Engang Wang Ke Han Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China National High Magnetic Field Laboratory Florida State UniversityTallahasseeFL 32310USA Oak Ridge National Laboratory Oak RidgeTN 37830USA FAMU-FSU College of Engineering TallahasseeFL 32310USA

In low-Ag Cu matrix alloys,the presence of coarse discontinuous precipitates may limit strength.We demonstrated that discontinuous Precipitation was suppressed,and continuous Precipitation was en-hanced by the doping of Cu-6 wt%Ag with Sc.A high-volume fraction of continuous precipitates,which nucleated on{111}planes,led to a 55 MPa increase in strength,with only a slight decrease in electri-cal conductivity.The addition of Sc inhibited the nucleation of discontinuous precipitates by causing the Sc and the Ag to co-segregate onto grain boundaries,thus forming a thin intermetallic compound layer between grains.After deformation,both discontinuous and continuous precipitates were drawn into Ag fibers.The combination of deformation strain and doping caused an increase in density and a decrease in the diameter of Ag fibers,resulting in about 205 MPa increase in doped samples when the deformation strain reached 4.9.The thinner,denser Ag fibers in the doped samples also caused higher electron scatter-ing at interfaces,leading to electrical conductivity that was 11%IACS lower than in non-doped samples.For reference,100%IACS(International Annealed Copper Standard)is equivalent to 1.7241μΩcm.

关键词： Sc doping Grain boundary segregation Precipitation Strength Electrical conductivity Plastic deformation

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Effect of quenching residual stress on Precipitation behaviour of 7085 aluminium alloy

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Journal of Materials Science & Technology 2023年第1期132卷 154-165页

作者： Jin Liu Zhiyong Du Jinlong Su Jie Tang Fulin Jiang Dingfa Fu Jie Teng Hui Zhang College of Materials Science and Engineering Hunan UniversityChangsha 410082China

The quenching-induced residual stress in ultrahigh strength Al-Zn-Mg-Cu alloys has a great influence on their Precipitation behaviour in subsequent heat treatment and the properties of the final products.In the present work,the cladding quenching method was employed for 7085 Al alloy slabs to tailor different quenching residual stresses.Then the effects of quenching residual stress on the Precipitation behaviour of the 7085 Al alloy were investigated through finite element analysis,residual stress and hardness distri-bution measurements and microstructural examinations.The results indicate that the reduction in resid-ual stress increases with increasing cladding layer thickness.For a cladding layer thickness in the range of 1-1.4 mm,the residual stress is almost eliminated.The hardness at the surface of the aged sample with a large compressive residual stress is decreased,while the hardness at the centre of the sample with a large tensile residual stress is increased.The hardness is approximately identical between the aged sam-ples with little or no residual stress.The elastic lattice distortion caused by residual stress is found to promote the nucleation of precipitates during the artificial ageing process.The in-depth mechanisms for the effect of quenching residual stress on the Precipitation of 7085 Al alloy are also discussed.

关键词： Aluminium alloy Quenching Residual stress Precipitation Finite element method

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气溶胶对降水影响的现象和机制

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Science Bulletin 2024年第10期69卷 1569-1580页

作者：赵传峰孙悦杨杰李杰峰周月杨以坤范昊赵辛 Department of Atmospheric and Oceanic Sciences School of Physicsand China Meteorological Administration Tornado Key LaboratoryPeking UniversityBeijing 100871China Institute of Carbon Neutrality Peking UniversityBeijing 100871China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China School of Environment Beijing Normal UniversityBeijing 100875China

Aerosols greatly influence Precipitation characteristics,thereby impacting the regional climate and human life.As an indispensable factor for cloud formation and a critical radiation budget regulator,aerosols can affect Precipitation intensity,frequency,geographical distribution,area,and time.However,discrepancies exist among current studies due to aerosol properties,Precipitation types,the vertical location of aerosols and meteorological conditions.The development of technology has driven advances in current research,but understanding the aerosol effects on Precipitation remain complex and challenging.This paper revolves around the following topics from the two perspectives of Aerosol-Radiation Interaction(ARI)and Aerosol-Cloud Interaction(ACI):(1)the influence of different vertical locations of absorbing/scattering aerosols on the atmospheric thermal structure;(2)the fundamental theories of ARI reducing surface wind speed,redistributing water vapour and energy,and then modulating Precipitation intensity;(3)different aerosol types(absorbing versus scattering)and aerosol concentrations causing different Precipitation diurnal and weekly variations;(4)microphysical processes(cloud water competition,invigoration effect,and evaporation cooling)and observational evidence of different effects of aerosols on Precipitation intensity,including enhancing,inhibiting,and transitional effects from enhancement to suppression;and(5)how meteorology,water vapor and dynamics influencing the effect of ACI and ARI on Precipitation.In addition,this review lists the existing issues and future research directions for attaining a more comprehensive understanding of aerosol effects on Precipitation.Overall,this review advances our understanding of aerosol effects on Precipitation and could guide the improvement of weather and climate models to predict complex aerosol-Precipitation interactions more accurately.

关键词： Aerosol Precipitation Aerosol-Radiation Interaction(ARI) Aerosol-Cloud Interaction(ACI) Mechanism

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Assessment of Wet Season Precipitation in the Central United States by the Regional Climate Simulation of the WRFG Member in NARCCAP and Its Relationship with Large-Scale Circulation Biases

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Advances in Atmospheric Sciences 2024年第4期41卷 619-638页

作者： Yating ZHAO Ming XUE Jing JIANG Xiao-Ming HU Anning HUANG School of Atmospheric Sciences Nanjing UniversityNanjing 210023China Center for Analysis and Prediction of Storms and School of Meteorology The University of OklahomaNorman 73072U.S.A

Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season Precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the Precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of Precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal Precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project Precipitation changes in future climate scenarios.

关键词： NARCCAP Central United States Precipitation low-level jet large-scale environment diurnal variation

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Effect of strain-induced Precipitation on microstructure and properties of titanium micro-alloyed steels

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Journal of Iron and Steel Research(International) 2022年第6期29卷 983-993页

作者： Xiang-dong Huo Zhi-wei Lv Chen Ao Lie-jun Li Ji-nian Xia Song-jun Chen School of Material Science and Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510640GuangdongChina Iron and Steel Research Institute Shandong Iron and Steel Group Rizhao Co.Ltd.Rizhao 276826ShandongChina

The strain-induced Precipitation behavior of titanium micro-alloyed steel was examined through the stress relaxation method.In addition,the relationship between strain-induced Precipitation and isothermal Precipitation was explored.The findings revealed that the strain-induced Precipitation and recrystallization processes of titanium micro-alloyed steel coexist and compete at the same time.The results also showed that the recrystallization process was inhibited with straininduced Precipitation.Moreover,a large amount of nano-sized TiC particles precipitated in Ti micro-alloyed steel.Notably,the strain-induced precipitated TiC had a size of 10 nm and isothermally precipitated TiC had a size of 3–6 nm.Additionally,there was a clear competitive relationship between strain-induced Precipitation and isothermal Precipitation.The findings also showed that strain-induced Precipitation had an obvious effect on the refinement of austenite although the effect was not obvious on the increase in the yield strength.Furthermore,isothermal treatment was shown to be more advantageous than strain-induced Precipitation.Finally,the major increase in the yield strength was mainly attributed to the Precipitation strengthening of nano-sized TiC during isothermal Precipitation.

关键词： Ti micro-alloyed steel Stress relaxation Nanometer-carbide Strain-induced Precipitation Isothermal Precipitation

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