Metal–organic frameworks(MOFs) have a regular porous structure and high porosity,which make them ideal electrode materials for supercapacitors.However,their capacitance performance is greatly limited by their poor co...Metal–organic frameworks(MOFs) have a regular porous structure and high porosity,which make them ideal electrode materials for supercapacitors.However,their capacitance performance is greatly limited by their poor conductivity.In this study,a multi-component hierarchical structure was obtained by growing NiCoFeLDH on the surface of ZIF-67,which increased the electron transfer between the MOF particles and greatly improved the capacitance of ZIF-67.The formation mechanism of the multicomponent layered hollow structure indicated that the hydrolysis acidity of metal ions and the coordination ability with ligands were the key factors for forming nanosheets and hollow structures.By controlling the type and valence state of the doped metals and the reaction time,the morphology transformation of MOF composites can be effectively controlled.Electrochemical studies showed that the specific capacitance of hollow NiCoFeLDH@ZIF-67 composite is 1202.08 F/g(0.5 A/g).In addition,aqueous devices were assembled and carefully tested.This scheme is crucial for the design of MOF-based materials used in supercapacitor devices and serves as a guide for the design of MOF-based composites.展开更多
基金supported by the National Natural Science Foundation of China (No.U1904215)Natural Science Foundation of Jiangsu Province (No.BK20200044)Changjiang scholars program of the Ministry of Education (No.Q2018270)。
文摘Metal–organic frameworks(MOFs) have a regular porous structure and high porosity,which make them ideal electrode materials for supercapacitors.However,their capacitance performance is greatly limited by their poor conductivity.In this study,a multi-component hierarchical structure was obtained by growing NiCoFeLDH on the surface of ZIF-67,which increased the electron transfer between the MOF particles and greatly improved the capacitance of ZIF-67.The formation mechanism of the multicomponent layered hollow structure indicated that the hydrolysis acidity of metal ions and the coordination ability with ligands were the key factors for forming nanosheets and hollow structures.By controlling the type and valence state of the doped metals and the reaction time,the morphology transformation of MOF composites can be effectively controlled.Electrochemical studies showed that the specific capacitance of hollow NiCoFeLDH@ZIF-67 composite is 1202.08 F/g(0.5 A/g).In addition,aqueous devices were assembled and carefully tested.This scheme is crucial for the design of MOF-based materials used in supercapacitor devices and serves as a guide for the design of MOF-based composites.
文摘目的探讨表观扩散系数(apparent diffusion coefficient,ADC)鉴别诊断肺癌脑转移瘤组织学分型的价值及其与Ki-67增殖指数之间的关系。材料与方法回顾性分析经手术病理证实的20例小细胞肺癌脑转移瘤和41例非小细胞肺癌脑转移瘤患者的资料,并测定其Ki-67增殖指数。在ADC图上测量肿瘤实性部分的最小ADC值(the minimum ADC,ADCmin)、平均ADC值(the mean ADC,ADCmean)及对侧正常脑白质ADC值,并计算相对ADCmin(relative ADCmin,rADCmin)及相对ADCmean(relative ADCmean,rADCmean)。对比分析二者ADC值的差异,绘制受试者工作特征(receiver operating characteristic,ROC)曲线评价ADC值的鉴别诊断价值,并计算ADC值与Ki-67增殖指数之间的相关性。结果小细胞肺癌脑转移瘤组的ADCmin、ADCmean、rADCmin及rADCmean值均小于非小细胞肺癌脑转移瘤组,组间差异均具有统计学意义(P<0.05)。各ADC值均能对小细胞肺癌脑转移瘤及非小细胞肺癌脑转移瘤进行有效鉴别,其中rADCmean值的鉴别诊断效能最好,曲线下面积(area under the curve,AUC)为0.950[95%置信区间(confidence interval,CI):0.907~0.994],最佳截断值为0.955,相应的敏感度和特异度分别为96.23%、83.87%,准确度为91.67%。小细胞肺癌脑转移瘤组的Ki-67增殖指数大于非小细胞肺癌脑转移瘤组,组间差异具有统计学意义(P<0.05)。61例肺癌脑转移瘤患者的ADCmin、ADCmean、rADCmin及rADCmean值均与Ki-67增殖指数呈不同程度的负相关(r=-0.506、r=-0.480、r=-0.569、r=-0.541)。结论ADC值可以对肺癌脑转移瘤的组织学分型进行鉴别诊断,并可以预测Ki-67增殖指数的表达水平。
