High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current puri...High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.展开更多
We report the successful growth and characterization of Li_9Cr_3(P_2O_7)_3(PO_4)_2single crystal,and investigate its magnetic properties under external magnetic fields via magnetization and heat capacity measurements....We report the successful growth and characterization of Li_9Cr_3(P_2O_7)_3(PO_4)_2single crystal,and investigate its magnetic properties under external magnetic fields via magnetization and heat capacity measurements.Our study reveals that Li_9Cr_3(P_2O_7)_3(PO_4)_2 is an easy-plane kagome ferromagnet with S=3/2,as evidenced by the Curie–Weiss temperature of 6 K which implies a ferromagnetic exchange coupling in the material.Under zero magnetic field,Li_9Cr_3(P_2O_7)_3(PO_4)_2 undergoes a magnetic transition at TC=2.7 K from a paramagnetic state to a ferromagnetically ordered state with the magnetic moment lying in the kagome plane.By applying a c-axis directional magnetic field to rotate the spin alignment from the kagome plane to the c-axis,we observe a reduction in the magnetic transition temperature as the field is increased.We construct a magnetic phase diagram as a function of temperature and magnetic field applied parallel to the c-axis of Li_9Cr_3(P_2O_7)_3(PO_4)_2 and find that the phase boundary is linear over a certain temperature range.Regarding that theoretically,the field-induced phase transition of the spin reorientation in the easy-plane ferromagnet can be viewed as the ferromagnetic magnon Bose–Einstein condensation(BEC),the phase boundary scaling of field-induced(B c)magnetic transition in Li_9Cr_3(P_2O_7)_3(PO_4)_2 can be described as the quasi-2D magnon BEC,which has been observed in other ferromagnetic materials such as K_2CuF_4.展开更多
目的了解2011-2014年深圳市孕妇乙型肝炎病毒(hepatitis B virus,HBV)感染状况,为预防和控制乙型肝炎(简称乙肝)母婴传播提供科学依据。方法对到助产机构初次进行产前检查的孕妇免费检测乙肝两对半,并由助产机构责任医生将孕妇的基本信...目的了解2011-2014年深圳市孕妇乙型肝炎病毒(hepatitis B virus,HBV)感染状况,为预防和控制乙型肝炎(简称乙肝)母婴传播提供科学依据。方法对到助产机构初次进行产前检查的孕妇免费检测乙肝两对半,并由助产机构责任医生将孕妇的基本信息及检测结果录入自主研发的信息管理系统,通过SPSS 19.0进行统计分析。结果深圳市孕妇乙肝表面抗原(hepatitis B surface antigen,HBsA g)阳性率、乙肝表面抗体(antibody to hepatitis B surface antigen,抗-HBs)阳性率、乙肝病毒e抗原(hepatitis B e antigen,HBeA g)阳性率、乙肝病毒e抗体(antibody to hepatitis B e antigen,抗-HBe)阳性率及乙肝病毒c抗体(antibody to hepatitis B core antigen,抗-HBc)阳性率分别为8.40%、47.84%、3.11%、12.28%、21.24%。不同年份、户籍类型、年龄、文化程度和职业的孕妇HBsA g、抗-HBs、HBeA g、抗-HBe和抗-HBc这五项指标阳性率之间的差异均有统计学意义(均有P<0.001)。结论深圳市孕妇HBsA g阳性率仍高于全国水平,半数以上孕妇没有检测到抗-HBs,流动人口孕妇HBV感染状况较常住人口严重。加强深圳市孕妇的免疫接种和查漏补种,有助于控制乙肝母婴传播。展开更多
基金Project supported by the Basic and Applied Basic Research Foundation of Guangdong Province,China(Grant Nos.2019A1515110302 and 2022A1515140003)the Key Research and Development Program of Guangdong Province,China(Grant Nos.2020B010189001,2021B0301030002,2019B010931001,and 2018B030327001)+5 种基金the National Natural Science Foundation of China(Grant Nos.52172035,52025023,52322205,51991342,52021006,51991344,52100115,11888101,92163206,12104018,and 12274456)the National Key Research and Development Program of China(Grant Nos.2021YFB3200303,2022YFA1405600,2018YFA0703700,2021YFA1400201,and 2021YFA1400502)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Pearl River Talent Recruitment Program of Guangdong Province,China(Grant No.2019ZT08C321)China Postdoctoral Science Foundation(Grant Nos.2020T130022 and 2020M680178)the Science and Technology Plan Project of Liaoning Province,China(Grant No.2021JH2/10100012).
文摘High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.
基金supported by the Key R&D Program of Guangdong Province(2020B010189001 and 2019B010931001)the National Natural Science Foundation of China(52025023,92163206,51991342,52021006,52172035,and 52202161)+4 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB33000000)the National Key R&D Program of China(2021YFA1400502,2021YFB3200303,and 2021YFA1400201)Guangdong Major Project of Basic and Applied Basic Research(2021B0301030002)the Fundamental Research Funds for the Central Universities(06500235)support from the National Program for Support of Top-notch Young Professionals。
基金Shenzhen Fundamental Research Program(Grant No.JCYJ20220818100405013)。
文摘We report the successful growth and characterization of Li_9Cr_3(P_2O_7)_3(PO_4)_2single crystal,and investigate its magnetic properties under external magnetic fields via magnetization and heat capacity measurements.Our study reveals that Li_9Cr_3(P_2O_7)_3(PO_4)_2 is an easy-plane kagome ferromagnet with S=3/2,as evidenced by the Curie–Weiss temperature of 6 K which implies a ferromagnetic exchange coupling in the material.Under zero magnetic field,Li_9Cr_3(P_2O_7)_3(PO_4)_2 undergoes a magnetic transition at TC=2.7 K from a paramagnetic state to a ferromagnetically ordered state with the magnetic moment lying in the kagome plane.By applying a c-axis directional magnetic field to rotate the spin alignment from the kagome plane to the c-axis,we observe a reduction in the magnetic transition temperature as the field is increased.We construct a magnetic phase diagram as a function of temperature and magnetic field applied parallel to the c-axis of Li_9Cr_3(P_2O_7)_3(PO_4)_2 and find that the phase boundary is linear over a certain temperature range.Regarding that theoretically,the field-induced phase transition of the spin reorientation in the easy-plane ferromagnet can be viewed as the ferromagnetic magnon Bose–Einstein condensation(BEC),the phase boundary scaling of field-induced(B c)magnetic transition in Li_9Cr_3(P_2O_7)_3(PO_4)_2 can be described as the quasi-2D magnon BEC,which has been observed in other ferromagnetic materials such as K_2CuF_4.
文摘目的了解2011-2014年深圳市孕妇乙型肝炎病毒(hepatitis B virus,HBV)感染状况,为预防和控制乙型肝炎(简称乙肝)母婴传播提供科学依据。方法对到助产机构初次进行产前检查的孕妇免费检测乙肝两对半,并由助产机构责任医生将孕妇的基本信息及检测结果录入自主研发的信息管理系统,通过SPSS 19.0进行统计分析。结果深圳市孕妇乙肝表面抗原(hepatitis B surface antigen,HBsA g)阳性率、乙肝表面抗体(antibody to hepatitis B surface antigen,抗-HBs)阳性率、乙肝病毒e抗原(hepatitis B e antigen,HBeA g)阳性率、乙肝病毒e抗体(antibody to hepatitis B e antigen,抗-HBe)阳性率及乙肝病毒c抗体(antibody to hepatitis B core antigen,抗-HBc)阳性率分别为8.40%、47.84%、3.11%、12.28%、21.24%。不同年份、户籍类型、年龄、文化程度和职业的孕妇HBsA g、抗-HBs、HBeA g、抗-HBe和抗-HBc这五项指标阳性率之间的差异均有统计学意义(均有P<0.001)。结论深圳市孕妇HBsA g阳性率仍高于全国水平,半数以上孕妇没有检测到抗-HBs,流动人口孕妇HBV感染状况较常住人口严重。加强深圳市孕妇的免疫接种和查漏补种,有助于控制乙肝母婴传播。
