Graphene-reinforced copper composites recently have attracted more attention, since they exhibited excellent mechanical properties and could be used widely in many fields. Few-layer graphene （FLG） and copper powder ...Graphene-reinforced copper composites recently have attracted more attention, since they exhibited excellent mechanical properties and could be used widely in many fields. Few-layer graphene （FLG） and copper powder were mixed by ball milling to produce homogeneous composite powders. Then, FLG-reinforced copper composites （FLG/Cu） were fabricated by spark plasma sintering （SPS） using the composite powders with a FLG volume fraction of 2.4 vol%. The effects of the rotating speed and the time of ball milling were analyzed based on the microstructure evolution and properties of the FLG/Cu composites. Obvious strengthening effect of FLG was found for the composites, and the conductance of the composite reaches 70.4% of IACS. The yield strength of the composite produced by ball milling at a speed of 100 r/rain for 4 h is 376 MPa, which is 2.5 times higher than that of copper and higher than that of copper composite enhanced by 5 vol% CNTs （360 MPa）. The defects produced in FLG with the increase of rotating speed and time could reduce the mechanical and conductive properties of the composites.展开更多
Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperat...Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperature deformation.Here,we report a novel strategy to boost the dislocation multiplication and accumulation during deformation at elevated temperatures through dynamic strain aging(DSA).With the introduction of the rare-earth element Ho in Mg-Y-Zn alloy,Ho atoms diffuse toward dislocations during deformation at elevated temperatures,provoking the DSA effect,which increases the dislocation density significantly via the interactions of mobile dislocations and Ho atoms.The resulting alloy achieves a great enhancement of dislocation hardening and obtains the dual benefits of high strength and good ductility simultaneously at high homologous temperatures.The present work provides an effective strategy to enhancing the strength and ductility for elevated-temperature materials.展开更多
目的通过Meta分析明确中国老年人孤独感的总体流行率及其在人群中的差异。方法检索PubMed、Embase、Web of Science等9个中英文数据库,检索时限自建库至2024年3月。2名研究者独立完成文献筛选、质量评价和信息提取,使用STATA 14.2软件...目的通过Meta分析明确中国老年人孤独感的总体流行率及其在人群中的差异。方法检索PubMed、Embase、Web of Science等9个中英文数据库,检索时限自建库至2024年3月。2名研究者独立完成文献筛选、质量评价和信息提取,使用STATA 14.2软件进行统计分析。结果共纳入58项研究,涉及271094名中国老年人。中国老年人孤独感的流行率为47.2%[95%CI(0.41,0.54)],且在性别、年龄、文化程度、婚姻状况、居住状况、与家庭成员的关系、慢性病、视听力障碍、经济状况、吸烟与否、兴趣爱好、运动锻炼、地域和测量工具等方面差异均有统计学意义(均P<0.05)。结论中国老年人孤独感流行率较高,不同人群间差异显著,未来需进一步探讨其风险和保护因素。展开更多
Achieving high strength in Mg alloys is usually accompanied by ductility loss.Here,a novel Mg97Y1Zn1Ho1 at.%alloy with a yield strength of 403 MPa and an elongation of 10%is developed.The strength-ductility synergy is...Achieving high strength in Mg alloys is usually accompanied by ductility loss.Here,a novel Mg97Y1Zn1Ho1 at.%alloy with a yield strength of 403 MPa and an elongation of 10%is developed.The strength-ductility synergy is obtained by a comprehensive strategy,including a lamella bimodal microstructure design and the introduction of nano-spaced solute-segregated 14H long-period stacking-ordered phase(14H LPSO phase)through rare-earth Ho alloying.The lamella bimodal microstructure consists of elongated un-recrystallized(un-DRXed)coarse grains and fine dynamically-recrystallized grains(DRXed regions).The nano-spaced solute-segregated 14H LPSO phase is distributed in DRXed regions.The outstanding yield strength is mainly contributed by grain-boundary strengthening,18R LPSO strengthening,and fiberlike reinforcement strengthening from the nano-spaced 14H LPSO phase.The high elongation is due primarily to the combined effects of the bimodal and lamellar microstructures through enhancing the work-hardening capability.展开更多
Reduced graphene oxide （RGO） and copper composites （RGO/Cu） were successfully fabricated based on a molecular-level mixing method （MLM）. The composite powders were reduced in H2 at 350, 450, and 550℃ and then c...Reduced graphene oxide （RGO） and copper composites （RGO/Cu） were successfully fabricated based on a molecular-level mixing method （MLM）. The composite powders were reduced in H2 at 350, 450, and 550℃ and then consolidated by spark plasma sintering （SPS） in order to evaluate the effect of H2 reduction temperature on the properties of the composites. The results indicate that the strengths of the composite decrease with the increase of H2 reduction temperature, while the electrical conductivity reaches its maximum at 450 ℃ and minimum at 550 ℃. Hot rolling could benefit the electrical conductivity. The yield strength of the RGO/Cu composite reduced to 337 MPa at 350℃. The electrical conductivity of the RGO/Cu composite reduced at 450℃ after hot rolling reaches 60.26% IACS. The properties of the RGO/Cu composites can be designed by adjusting the reduction degree of RGO and by hot rolling.展开更多
Deformation-induced twinning or martensitic transformation can improve the work-hardening capabil-ity of alloys with face-centered cubic(FCC)structures and suppress strain localization.The stacking fault energy(SFE)of...Deformation-induced twinning or martensitic transformation can improve the work-hardening capabil-ity of alloys with face-centered cubic(FCC)structures and suppress strain localization.The stacking fault energy(SFE)of alloys plays a key role in determining deformation mechanisms and mechanical prop-erties.This study developed V-bearing high-Mn steel with a tensile strength of 1288 MPa and uniform elongation of 36%by tactfully designing the composition.Precipitation of V-carbides was selected to strengthen the steel and tune the global SFE of the matrix by settling carbon.Stronger work-hardening capability due to lower SFE and finer twin/matrix lamellae provided the steel with good ductility,while precipitation strengthened it.展开更多
We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where t...We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where the hohlraum is composed of a single metal liner,a low-Z plastic foam,and a high-Z metallic foam.The implosion dynamics of a hohlraum and a multi-shell target are investigated separately by the one-dimensional code MULTI-IFE.When the peak drive current is 50 MA,simulations suggest that an x-ray pulse with nearly constant radiation temperature(-310 eV)and a duration about 9 ns can be obtained.A small multi-shell target with a radius of 1.35 mm driven by this radiation pulse is able to achieve volumetric ignition with an energy gain(G)about 6.19,where G is the ratio of the yield to the absorbed radiation.Through this research,we better understand the effects of non-uniformities and hydrodynamics instabilities in Z-pinch dynamic hohlraum.展开更多
Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a grou...Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a group A bZIP gene from“Kyoho”grapevine,VlbZIP30,which was shown to be induced by abscisic acid(ABA)and dehydration stress.Overexpression of VlbZIP30 in transgenic Arabidopsis thaliana enhanced dehydration tolerance.Transcriptome analysis revealed that a major proportion of ABA-responsive and/or drought-responsive genes are transcriptionally regulated by VlbZIP30 during ABA or mannitol treatment at the cotyledon greening stage.We identified an A.thaliana G-box motif(CACGTG)and a potential grapevine G-box motif(MCACGTGK)in the promoters of the 39 selected A.thaliana genes upregulated in the transgenic plants and in the 35 grapevine homologs,respectively.Subsequently,using two grapevine-related databases,we found that 74%(23/31)and 84%(21/25)of the detected grapevine genes were significantly upregulated by ABA and drought stress,respectively,suggesting that these genes are involved in ABA or dehydration stress and may be regulated by VlbZIP30 in grapevine.We propose that VlbZIP30 functions as a positive regulator of dehydration-responsive signaling in the ABA core signaling pathway.展开更多
基金financially supported by the National Basic Research Program of China (No.2011CB612200)Program of Qinghai Science and Technology Department (2012-Z701)+1 种基金China Scholarship Council (No.201206125006)Harbin Key Technologies R&D Program (2012DB2CP029)
文摘Graphene-reinforced copper composites recently have attracted more attention, since they exhibited excellent mechanical properties and could be used widely in many fields. Few-layer graphene （FLG） and copper powder were mixed by ball milling to produce homogeneous composite powders. Then, FLG-reinforced copper composites （FLG/Cu） were fabricated by spark plasma sintering （SPS） using the composite powders with a FLG volume fraction of 2.4 vol%. The effects of the rotating speed and the time of ball milling were analyzed based on the microstructure evolution and properties of the FLG/Cu composites. Obvious strengthening effect of FLG was found for the composites, and the conductance of the composite reaches 70.4% of IACS. The yield strength of the composite produced by ball milling at a speed of 100 r/rain for 4 h is 376 MPa, which is 2.5 times higher than that of copper and higher than that of copper composite enhanced by 5 vol% CNTs （360 MPa）. The defects produced in FLG with the increase of rotating speed and time could reduce the mechanical and conductive properties of the composites.
基金supported by the National Key Research and Development Project(2023YFA1609100)the NSFC Funding(U2141207,52171111,52001083)+6 种基金Natural Science Foundation of Heilongjiang(YQ2023E026)China Postdoctoral Science foundation(2024M754149)Postdoctoral Fellowship Program of CPSF(GZC20242192)support from the National Science Foundation(DMR-1611180 and 1809640)with the program directors,DrsHKU Seed Fund for Collaborative Research(#2207101618)support by Croucher Senior Research Fellowship and City U Project(Project No.9229019)Shenzhen Science and Technology Program(Project No.JCYJ20220818101203007)。
文摘Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperature deformation.Here,we report a novel strategy to boost the dislocation multiplication and accumulation during deformation at elevated temperatures through dynamic strain aging(DSA).With the introduction of the rare-earth element Ho in Mg-Y-Zn alloy,Ho atoms diffuse toward dislocations during deformation at elevated temperatures,provoking the DSA effect,which increases the dislocation density significantly via the interactions of mobile dislocations and Ho atoms.The resulting alloy achieves a great enhancement of dislocation hardening and obtains the dual benefits of high strength and good ductility simultaneously at high homologous temperatures.The present work provides an effective strategy to enhancing the strength and ductility for elevated-temperature materials.
文摘目的通过Meta分析明确中国老年人孤独感的总体流行率及其在人群中的差异。方法检索PubMed、Embase、Web of Science等9个中英文数据库,检索时限自建库至2024年3月。2名研究者独立完成文献筛选、质量评价和信息提取,使用STATA 14.2软件进行统计分析。结果共纳入58项研究,涉及271094名中国老年人。中国老年人孤独感的流行率为47.2%[95%CI(0.41,0.54)],且在性别、年龄、文化程度、婚姻状况、居住状况、与家庭成员的关系、慢性病、视听力障碍、经济状况、吸烟与否、兴趣爱好、运动锻炼、地域和测量工具等方面差异均有统计学意义(均P<0.05)。结论中国老年人孤独感流行率较高,不同人群间差异显著,未来需进一步探讨其风险和保护因素。
基金supported by the National Key Research and Development Project (2018YFE0115800, 2020YFE0202600)Youth Talent Project of China National Nuclear Corporation (CNNC2019YTEP-HEU01, CNNC2021YTEP-HEU01)+4 种基金the NSFC Funding (51701051, 52001083, 52171111, U2141207)China Postdoctoral Science Foundation Funded Project (2019T120255)Natural Science Foundation of Heilongjiang (LH2019E030)Heilongjiang Touyan Innovation Team Programthe supports from the U.S. National Science Foundation [DMR-1611180 and 1809640] with the program directors, Drs. Judith Yang, Gary Shiflet, and Diana Farkas.
文摘Achieving high strength in Mg alloys is usually accompanied by ductility loss.Here,a novel Mg97Y1Zn1Ho1 at.%alloy with a yield strength of 403 MPa and an elongation of 10%is developed.The strength-ductility synergy is obtained by a comprehensive strategy,including a lamella bimodal microstructure design and the introduction of nano-spaced solute-segregated 14H long-period stacking-ordered phase(14H LPSO phase)through rare-earth Ho alloying.The lamella bimodal microstructure consists of elongated un-recrystallized(un-DRXed)coarse grains and fine dynamically-recrystallized grains(DRXed regions).The nano-spaced solute-segregated 14H LPSO phase is distributed in DRXed regions.The outstanding yield strength is mainly contributed by grain-boundary strengthening,18R LPSO strengthening,and fiberlike reinforcement strengthening from the nano-spaced 14H LPSO phase.The high elongation is due primarily to the combined effects of the bimodal and lamellar microstructures through enhancing the work-hardening capability.
基金financially supported by the National Basic Research Program of China (No.2011CB612200)Program of Qinghai Science and Technology Department (No.2012-Z-701)Harbin Key Technologies R&D Program (No.2012DB2CP029)
文摘Reduced graphene oxide （RGO） and copper composites （RGO/Cu） were successfully fabricated based on a molecular-level mixing method （MLM）. The composite powders were reduced in H2 at 350, 450, and 550℃ and then consolidated by spark plasma sintering （SPS） in order to evaluate the effect of H2 reduction temperature on the properties of the composites. The results indicate that the strengths of the composite decrease with the increase of H2 reduction temperature, while the electrical conductivity reaches its maximum at 450 ℃ and minimum at 550 ℃. Hot rolling could benefit the electrical conductivity. The yield strength of the RGO/Cu composite reduced to 337 MPa at 350℃. The electrical conductivity of the RGO/Cu composite reduced at 450℃ after hot rolling reaches 60.26% IACS. The properties of the RGO/Cu composites can be designed by adjusting the reduction degree of RGO and by hot rolling.
基金The present work was supported by the Natural Science Foundation of China(Nos.52171111,U2141207,52001083)the Youth Talent Project of China National Nuclear Corporation(No.CNNC2021Y-TEP-HEU01)+2 种基金the China Postdoctoral Science Founda-tion(No.2020M681077)the Natural Science Foundation of Hei-longjiang(No.LH2019E030)the Heilongjiang Postdoctoral Science Foundation(No.LBH-Z19125)and Heilongjiang Touyan Innovation Team Program.
文摘Deformation-induced twinning or martensitic transformation can improve the work-hardening capabil-ity of alloys with face-centered cubic(FCC)structures and suppress strain localization.The stacking fault energy(SFE)of alloys plays a key role in determining deformation mechanisms and mechanical prop-erties.This study developed V-bearing high-Mn steel with a tensile strength of 1288 MPa and uniform elongation of 36%by tactfully designing the composition.Precipitation of V-carbides was selected to strengthen the steel and tune the global SFE of the matrix by settling carbon.Stronger work-hardening capability due to lower SFE and finer twin/matrix lamellae provided the steel with good ductility,while precipitation strengthened it.
基金Project supported by the Science Challenge Project (Grant No. TZ2018001)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos. XDA25051200 and XDA25050200)+4 种基金the National Natural Science Foundation of China (Grant Nos. 11705282 and 11775305)Hunan Graduate Scientific Research Innovation Project (Grant No. CX20190001)supported by the spanish “Ministerio de Ciencia Innovación y Universidades”project RTI2018-098801-B-100the Spanish “Ministerio de Economía y Competitividad” Project ENE2014-54960-Rthe EURO fusion Consortium project AWP15-ENR-01/CEA-02
文摘We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse.The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration,where the hohlraum is composed of a single metal liner,a low-Z plastic foam,and a high-Z metallic foam.The implosion dynamics of a hohlraum and a multi-shell target are investigated separately by the one-dimensional code MULTI-IFE.When the peak drive current is 50 MA,simulations suggest that an x-ray pulse with nearly constant radiation temperature(-310 eV)and a duration about 9 ns can be obtained.A small multi-shell target with a radius of 1.35 mm driven by this radiation pulse is able to achieve volumetric ignition with an energy gain(G)about 6.19,where G is the ratio of the yield to the absorbed radiation.Through this research,we better understand the effects of non-uniformities and hydrodynamics instabilities in Z-pinch dynamic hohlraum.
基金This work was supported by the National Natural Science Foundation of China(31572110)as well as the Program for Innovative Research Team of Grape Germplasm Resources and Breeding(2013KCT-25).
文摘Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a group A bZIP gene from“Kyoho”grapevine,VlbZIP30,which was shown to be induced by abscisic acid(ABA)and dehydration stress.Overexpression of VlbZIP30 in transgenic Arabidopsis thaliana enhanced dehydration tolerance.Transcriptome analysis revealed that a major proportion of ABA-responsive and/or drought-responsive genes are transcriptionally regulated by VlbZIP30 during ABA or mannitol treatment at the cotyledon greening stage.We identified an A.thaliana G-box motif(CACGTG)and a potential grapevine G-box motif(MCACGTGK)in the promoters of the 39 selected A.thaliana genes upregulated in the transgenic plants and in the 35 grapevine homologs,respectively.Subsequently,using two grapevine-related databases,we found that 74%(23/31)and 84%(21/25)of the detected grapevine genes were significantly upregulated by ABA and drought stress,respectively,suggesting that these genes are involved in ABA or dehydration stress and may be regulated by VlbZIP30 in grapevine.We propose that VlbZIP30 functions as a positive regulator of dehydration-responsive signaling in the ABA core signaling pathway.
