While alloying transition metal chalcogenides(TMCs)with other chalcogen elements can effectively improve their conductivity and electrochemical properties,the optimal alloying content is still uncertain.In this study,...While alloying transition metal chalcogenides(TMCs)with other chalcogen elements can effectively improve their conductivity and electrochemical properties,the optimal alloying content is still uncertain.In this study,we study the influence of dopant concentration on the chemical bonds in TMC and reveal the associated stepwise conversion reaction mechanism for potassium ion storage.According to density function theory calculations,appropriate S-doping in Co0.85Se(Co_(0.85)Se_(1-x)S_(x))can reduce the average length of Co-Co bonds because of the electronegativity variation,which is thermodynamically favourable to the phase transition reactions.The optimal Se/S ratio(x=0.12)for the conductivity has been obtained from experimental results.When assembled as an anode in potassium-ion batteries(PIBs),the sample with optimized Se/S ratio exhibits extraordinary electrochemical performance.The rate performance(229.2 mA h g^(-1)at 10 A g^(-1))is superior to the state-of-the-art results.When assembled with Prussian blue(PB)as a cathode,the pouch cell exhibits excellent performance,demonstrating its great potential for applications.Moreover,the stepwise K+storage mechanism caused by the coexistence of S and Se is revealed by in-situ X-ray diffraction and ex-situ transmission electron microscopy techniques.Hence,this work not only provides an effective strategy to enhance the electrochemical performance of transition metal chalcogenides but also reveals the underlying mechanism for the construction of advanced electrode materials.展开更多
第四纪气候波动以及地理和环境隔离深刻地影响了现代植物的遗传多样性、遗传结构和地理分布格局。该研究采用分子谱系地理学的研究方法对药用植物半夏19个居群共212个个体的3个叶绿体片段psb K-psb I、atp F-atp H和trn L-F进行分析,探...第四纪气候波动以及地理和环境隔离深刻地影响了现代植物的遗传多样性、遗传结构和地理分布格局。该研究采用分子谱系地理学的研究方法对药用植物半夏19个居群共212个个体的3个叶绿体片段psb K-psb I、atp F-atp H和trn L-F进行分析,探究半夏的遗传多样性、遗传结构、地理分布格局模式及成因,并探讨其居群历史动态。结果表明:(1)半夏总单倍型多样性H d为0.882,总核苷酸多样性π为1.23×10-3,在物种水平上表现出较高的遗传多样性。(2)分子方差分析(AMOVA)结果显示,半夏遗传变异主要发生在居群间,显著的遗传分化(F ST=0.909,P<0.001)和较低的种群内遗传多样性(H S=0.134);种群间遗传分化系数N ST=0.913>G ST=0.855(0.01<P<0.05),表明叶绿体单倍型具有明显的谱系地理结构。(3)中性检验结果显示,Tajima s D值、Fu and Li s D值以及Fu and Li s F值均为不显著正值,Fu s Fs值为不显著负值且失配分析曲线呈双峰,表明半夏居群整体没有经历过扩张事件。(4)单倍型地理分布显示,西南地区和中-东部地区具有单倍型多样性较高,并存在特有单倍型,故推测第四纪冰期时在这两个区域存在冰期避难所。总之,通过3个叶绿体基因对不同区域半夏的分析,阐明了其遗传多样性、遗传结构和地理分布格局,为半夏优良种源的分子筛选和保护提出了科学的建议和保护策略。展开更多
目的探讨前次剖宫产手术时机对再孕阴道分娩母婴并发症的影响。方法回顾性分析本院收治的1034例足月剖宫产术后阴道分娩(VBAC)孕产妇资料。按前次剖宫产手术时机分为择期组(择期行剖宫产术)426例、第一产程组(第一产程行剖宫产术)278例...目的探讨前次剖宫产手术时机对再孕阴道分娩母婴并发症的影响。方法回顾性分析本院收治的1034例足月剖宫产术后阴道分娩(VBAC)孕产妇资料。按前次剖宫产手术时机分为择期组(择期行剖宫产术)426例、第一产程组(第一产程行剖宫产术)278例、第二产程组(第二产程行剖宫产术)330例。分析前次剖宫产手术时机对VBAC孕产妇的产程、产后并发症及新生儿出生情况的影响。结果第二产程组子宫收缩乏力比例、产后24 h出血量、产后出血发生率及产后住院天数均大于择期组和第一产程组(P<0.05),而择期组与第一产程组比较,以上指标差异无统计学意义(P>0.05)。3组间第二、第三产程时限、助产率、会阴裂伤率、产后尿潴留率、发热比例及新生儿1 min Apgar评分、新生儿窒息发生率及转入新生儿科比例比较,差异无统计学意义(P>0.05)。结论前次第二产程剖宫产手术孕产妇再孕阴道分娩时发生子宫收缩乏力及产后出血风险增加。展开更多
基金financially supported by the Natural Science Foundation of Jiangsu Province of China(BK20211172)the Jiangsu Provincial Department of Science and Technology Innovation Support Program(BK20222004,BZ2022036)+1 种基金the National Natural Science Foundation of China(52002366,22075263)the Fundamental Research Funds for the Central Universities(WK2060000039)。
文摘While alloying transition metal chalcogenides(TMCs)with other chalcogen elements can effectively improve their conductivity and electrochemical properties,the optimal alloying content is still uncertain.In this study,we study the influence of dopant concentration on the chemical bonds in TMC and reveal the associated stepwise conversion reaction mechanism for potassium ion storage.According to density function theory calculations,appropriate S-doping in Co0.85Se(Co_(0.85)Se_(1-x)S_(x))can reduce the average length of Co-Co bonds because of the electronegativity variation,which is thermodynamically favourable to the phase transition reactions.The optimal Se/S ratio(x=0.12)for the conductivity has been obtained from experimental results.When assembled as an anode in potassium-ion batteries(PIBs),the sample with optimized Se/S ratio exhibits extraordinary electrochemical performance.The rate performance(229.2 mA h g^(-1)at 10 A g^(-1))is superior to the state-of-the-art results.When assembled with Prussian blue(PB)as a cathode,the pouch cell exhibits excellent performance,demonstrating its great potential for applications.Moreover,the stepwise K+storage mechanism caused by the coexistence of S and Se is revealed by in-situ X-ray diffraction and ex-situ transmission electron microscopy techniques.Hence,this work not only provides an effective strategy to enhance the electrochemical performance of transition metal chalcogenides but also reveals the underlying mechanism for the construction of advanced electrode materials.
文摘第四纪气候波动以及地理和环境隔离深刻地影响了现代植物的遗传多样性、遗传结构和地理分布格局。该研究采用分子谱系地理学的研究方法对药用植物半夏19个居群共212个个体的3个叶绿体片段psb K-psb I、atp F-atp H和trn L-F进行分析,探究半夏的遗传多样性、遗传结构、地理分布格局模式及成因,并探讨其居群历史动态。结果表明:(1)半夏总单倍型多样性H d为0.882,总核苷酸多样性π为1.23×10-3,在物种水平上表现出较高的遗传多样性。(2)分子方差分析(AMOVA)结果显示,半夏遗传变异主要发生在居群间,显著的遗传分化(F ST=0.909,P<0.001)和较低的种群内遗传多样性(H S=0.134);种群间遗传分化系数N ST=0.913>G ST=0.855(0.01<P<0.05),表明叶绿体单倍型具有明显的谱系地理结构。(3)中性检验结果显示,Tajima s D值、Fu and Li s D值以及Fu and Li s F值均为不显著正值,Fu s Fs值为不显著负值且失配分析曲线呈双峰,表明半夏居群整体没有经历过扩张事件。(4)单倍型地理分布显示,西南地区和中-东部地区具有单倍型多样性较高,并存在特有单倍型,故推测第四纪冰期时在这两个区域存在冰期避难所。总之,通过3个叶绿体基因对不同区域半夏的分析,阐明了其遗传多样性、遗传结构和地理分布格局,为半夏优良种源的分子筛选和保护提出了科学的建议和保护策略。
文摘目的探讨前次剖宫产手术时机对再孕阴道分娩母婴并发症的影响。方法回顾性分析本院收治的1034例足月剖宫产术后阴道分娩(VBAC)孕产妇资料。按前次剖宫产手术时机分为择期组(择期行剖宫产术)426例、第一产程组(第一产程行剖宫产术)278例、第二产程组(第二产程行剖宫产术)330例。分析前次剖宫产手术时机对VBAC孕产妇的产程、产后并发症及新生儿出生情况的影响。结果第二产程组子宫收缩乏力比例、产后24 h出血量、产后出血发生率及产后住院天数均大于择期组和第一产程组(P<0.05),而择期组与第一产程组比较,以上指标差异无统计学意义(P>0.05)。3组间第二、第三产程时限、助产率、会阴裂伤率、产后尿潴留率、发热比例及新生儿1 min Apgar评分、新生儿窒息发生率及转入新生儿科比例比较,差异无统计学意义(P>0.05)。结论前次第二产程剖宫产手术孕产妇再孕阴道分娩时发生子宫收缩乏力及产后出血风险增加。
