Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metalli...Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metallization and superconductivity of fluorine were achieved in MgF_(5)at 120 GPa by exploiting the high-pressure s-d transition of doped Mg.The unexpected Mg-F covalent bonding induced by Mg-d and F-p orbital interactions led to fluorine metallization and the formation of an F skeleton similar to a H-cage.The high density of states(DOS)from the F skeleton and phonon softening from strong Fermi surface nesting contribute to a high superconducting transition temperature(Tc).The Tc of Pmmm-MgF_(5)at 120 GPa is 14.02 K,with strong electron-phonon coupling(λ=0.84),which is close to that of Li_(6)P at 270 GPa(λ=1.01).This is the first observation of superconductivity in main-group metal fluorides.Additionally,two near-monatomic F atoms exist in the interstitial region of MgF_(5),significantly enhancing electron-phonon coupling.This work challenges the traditional view of main-group metal fluorides and provides deeper insights into the superconductivity and physicochemical properties of fluorine.展开更多
Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO_(2)(CO_(2)RR),while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of^...Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO_(2)(CO_(2)RR),while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of^(*)CO intermediates.Although the introduction of heteroatoms or transition metal sites can modulate the binding strength of^(*)CO on Fe sites,these regulators often induce competitive hydrogen evolution reaction(HER)with reduced Faraday efficiency(FE).In this work,we employ HER-inert Sn as a regulator to tune the electronic structure of Fe,weakening^(*)CO adsorption and enhancing CO_(2)RR performance.Diatomic Fe-Sn pairs supported on N-doped carbon(Fe-Sn/NC)were synthesized,achieving FE for CO exceeding 90%over a broad potential range from−0.4 to−0.9 V versus the reversible hydrogen electrode.Fe-Sn/NC shows a high turnover frequency of 1.5×10^(4)h^(-1),much higher than that of Fe/NC.Characterization results and theoretical calculations demonstrate that bonding Sn site to Fe generates electron-rich Fe centers,effectively reducing the adsorption strength of^(*)CO without triggering HER.Additionally,Fe-Sn/NC exhibits exceptional activity in hydrazine oxidation performance(HzOR).The HzOR-assisted CO_(2)RR system using Fe-Sn/NC as electrodes reduces energy consumption by 38%compared with the conventional CO_(2)RR coupled oxygen evolution reaction system.展开更多
Synthesis of stable main-group element-based radicals represents one of the most interesting topics in contemporary organometallic chem- istry, because of their vital roles in organic, inorganic and biological chemist...Synthesis of stable main-group element-based radicals represents one of the most interesting topics in contemporary organometallic chem- istry, because of their vital roles in organic, inorganic and biological chemistry as well as materials science. However, the access of stable main-group element-based radicals is highly challenging owing to the lack of energetically accessible orbitals in the main-group elements. During the last decades, several synthetic strategies have been developed in obtaining these reactive species. Among them, utilizing the stericaliy demanding substituents and x-conjugated ligands has proven to be an effective approach. Weakly coordinating ions （WCAs） have also been found to be exceptionally practical in synthesizing radical cations of main-group elements. By introducing these stabilization methods, we have successfully prepared a variety of radical ions of p-block elements in the crystalline forms, and investigated their properties by different experimental and quantum chemical calculation methods. According to the investigations, magnetic stability was observed, resulting from the intramolecular electron-exchange interaction. Furthermore, we also found that the singlet-triptet energy gaps of the bis（triarylamine） diradical dications can be tunable by varying the temperature. These investigations open new avenues of the main-group element-based radicals for a large variety of applications.展开更多
目的基于H医院本土化的以资源为基础的相对价值量表(resource-based relative value scale,RBRVS)实施以主手术为核心的手术绩效管理模式改革,构建更加科学公平的手术绩效分配体系。方法构建以主手术为核心的手术绩效管理模式,收集整理...目的基于H医院本土化的以资源为基础的相对价值量表(resource-based relative value scale,RBRVS)实施以主手术为核心的手术绩效管理模式改革,构建更加科学公平的手术绩效分配体系。方法构建以主手术为核心的手术绩效管理模式,收集整理H医院2023年全年65915台住院择期手术的RBRVS、疾病诊断相关分组(diagnosis related groups,DRG)、病例组合指数(case mixed index,CMI)、手术时间等相关数据,采用SPSS软件进行大样本历史数据分析,通过关键指标验证优化后手术绩效管理模式的合理性。结果纳入研究的22个科室多条医嘱手术总系数与主手术系数均高度拟合(γ>0.85),各专科匹配系数均差异显著(P<0.001),以主手术为核心的手术绩效管理模式对关键指标(医生时间资源投入和手术风险难度)的体现得到明显提升。结论通过实施以主手术为核心的手术绩效管理模式,强化体现诊疗风险及难易程度、医生劳务价值的绩效导向,引导临床回归医疗本质,支撑学科建设发展,进一步激发临床工作活力和动力。展开更多
基金supported by the National Natural Science Foundation of China(Nos.12374004 and 12174141)the National Key R&D Program of China(No.2023YFA1406200)。
文摘Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metallization and superconductivity of fluorine were achieved in MgF_(5)at 120 GPa by exploiting the high-pressure s-d transition of doped Mg.The unexpected Mg-F covalent bonding induced by Mg-d and F-p orbital interactions led to fluorine metallization and the formation of an F skeleton similar to a H-cage.The high density of states(DOS)from the F skeleton and phonon softening from strong Fermi surface nesting contribute to a high superconducting transition temperature(Tc).The Tc of Pmmm-MgF_(5)at 120 GPa is 14.02 K,with strong electron-phonon coupling(λ=0.84),which is close to that of Li_(6)P at 270 GPa(λ=1.01).This is the first observation of superconductivity in main-group metal fluorides.Additionally,two near-monatomic F atoms exist in the interstitial region of MgF_(5),significantly enhancing electron-phonon coupling.This work challenges the traditional view of main-group metal fluorides and provides deeper insights into the superconductivity and physicochemical properties of fluorine.
文摘Single-atom Fe catalysts show significant promise in the electrocatalytic reduction of CO_(2)(CO_(2)RR),while their performance remains inferior to that of precious metal catalysts due to the overly strong binding of^(*)CO intermediates.Although the introduction of heteroatoms or transition metal sites can modulate the binding strength of^(*)CO on Fe sites,these regulators often induce competitive hydrogen evolution reaction(HER)with reduced Faraday efficiency(FE).In this work,we employ HER-inert Sn as a regulator to tune the electronic structure of Fe,weakening^(*)CO adsorption and enhancing CO_(2)RR performance.Diatomic Fe-Sn pairs supported on N-doped carbon(Fe-Sn/NC)were synthesized,achieving FE for CO exceeding 90%over a broad potential range from−0.4 to−0.9 V versus the reversible hydrogen electrode.Fe-Sn/NC shows a high turnover frequency of 1.5×10^(4)h^(-1),much higher than that of Fe/NC.Characterization results and theoretical calculations demonstrate that bonding Sn site to Fe generates electron-rich Fe centers,effectively reducing the adsorption strength of^(*)CO without triggering HER.Additionally,Fe-Sn/NC exhibits exceptional activity in hydrazine oxidation performance(HzOR).The HzOR-assisted CO_(2)RR system using Fe-Sn/NC as electrodes reduces energy consumption by 38%compared with the conventional CO_(2)RR coupled oxygen evolution reaction system.
基金We thank the National Key R＆D Program of China （Grant 2016YFA0300404, X.W.） and the National Natural Science Foundation of China （Grants 21525102, 21690062, X.W. and 21601082, G.T.） for financial support. Dr. Li Zhang is acknowledged for proofreading the manuscript.
文摘Synthesis of stable main-group element-based radicals represents one of the most interesting topics in contemporary organometallic chem- istry, because of their vital roles in organic, inorganic and biological chemistry as well as materials science. However, the access of stable main-group element-based radicals is highly challenging owing to the lack of energetically accessible orbitals in the main-group elements. During the last decades, several synthetic strategies have been developed in obtaining these reactive species. Among them, utilizing the stericaliy demanding substituents and x-conjugated ligands has proven to be an effective approach. Weakly coordinating ions （WCAs） have also been found to be exceptionally practical in synthesizing radical cations of main-group elements. By introducing these stabilization methods, we have successfully prepared a variety of radical ions of p-block elements in the crystalline forms, and investigated their properties by different experimental and quantum chemical calculation methods. According to the investigations, magnetic stability was observed, resulting from the intramolecular electron-exchange interaction. Furthermore, we also found that the singlet-triptet energy gaps of the bis（triarylamine） diradical dications can be tunable by varying the temperature. These investigations open new avenues of the main-group element-based radicals for a large variety of applications.
文摘目的基于H医院本土化的以资源为基础的相对价值量表(resource-based relative value scale,RBRVS)实施以主手术为核心的手术绩效管理模式改革,构建更加科学公平的手术绩效分配体系。方法构建以主手术为核心的手术绩效管理模式,收集整理H医院2023年全年65915台住院择期手术的RBRVS、疾病诊断相关分组(diagnosis related groups,DRG)、病例组合指数(case mixed index,CMI)、手术时间等相关数据,采用SPSS软件进行大样本历史数据分析,通过关键指标验证优化后手术绩效管理模式的合理性。结果纳入研究的22个科室多条医嘱手术总系数与主手术系数均高度拟合(γ>0.85),各专科匹配系数均差异显著(P<0.001),以主手术为核心的手术绩效管理模式对关键指标(医生时间资源投入和手术风险难度)的体现得到明显提升。结论通过实施以主手术为核心的手术绩效管理模式,强化体现诊疗风险及难易程度、医生劳务价值的绩效导向,引导临床回归医疗本质,支撑学科建设发展,进一步激发临床工作活力和动力。
