Divalent IIA metals such as Be, Mg, Ca, Sr, Ba and transition IIB metals such as Zn, Cd were investigated as possible n-type dopants into the Cu2 O theoretically by using the first-principles calculations based on den...Divalent IIA metals such as Be, Mg, Ca, Sr, Ba and transition IIB metals such as Zn, Cd were investigated as possible n-type dopants into the Cu2 O theoretically by using the first-principles calculations based on density functional theory. By systematical analyses of the lattice parameters, the bond length, the electronic structure, the local density of states and the defect formation energy for various doping systems, it is revealed that Ca, Sr, Ba and Be are more suited for n-type doping into Cu2O as shallow donors, compared to Mg which introduces a relatively deep donor level in Cu2O. Meanwhile, Zn and Cd can hardly be doped into Cu2O due to the positive formation energy of relevant defects.展开更多
The solvent extraction process combined with tools of experimental design assists in developing procedures for separation and purification of elements or mineral compounds with high purity. In this work the technique ...The solvent extraction process combined with tools of experimental design assists in developing procedures for separation and purification of elements or mineral compounds with high purity. In this work the technique was used to replace the traditional methods for the collection of basic information required for the development of a circuit of solvent extraction. According to the literature, several factors may influence the extraction of divalent metals by D2EHPA in sulfate media, among which the concentration of metals in solution. The objective was to study the variables affecting the separation process Mn/Ni/Co/Cu, such as the aqueous/organic (A/O), contact time, concentrations of the divalent metals in sulfuric medium, pH and solvent concentration. An investigation into the variables that control the process was done using a “cube + star” experimental design, with central point. The results demonstrate it is possible to obtain of a satisfactory mathematical model that describes the process.展开更多
目的研究巴罗沙星与 DNA 的分子作用机制和 Mg^(2+)对巴罗沙星与 DNA 相互作用的影响。方法利片J荧光光谱研究巴罗沙星与 DNA 的作用强度并计算热力学数据ΔH;利用紫外光谱、黏度测定、竞争实验、与变性 DNA作用的比较等方法确定巴罗沙...目的研究巴罗沙星与 DNA 的分子作用机制和 Mg^(2+)对巴罗沙星与 DNA 相互作用的影响。方法利片J荧光光谱研究巴罗沙星与 DNA 的作用强度并计算热力学数据ΔH;利用紫外光谱、黏度测定、竞争实验、与变性 DNA作用的比较等方法确定巴罗沙星与小牛胸腺 DNA 的相互作用方式;利用荧光光谱考察 Mg^(2+)对巴罗沙星与小牛胸腺DNA 相互作用的影响。结果 DNA 对巴罗沙星的荧光猝灭常数为(5.43±0.07)×10~3L·mol^(-1),ΔH=-8.03 kJ·mol^(-1);Mg^(2+)使巴罗沙星与 DNA 的作用增强。结论巴罗沙星以沟槽键合方式与 DNA 相瓦作用;Mg^(2+)对巴罗沙星与 DNA 的结合有中介作用。展开更多
The glucose isomerase(GI) was a metal activating enzyme It was most activated by Co 2+ and Mg 2+ ,and Mg 2+ was the best activator,whether the glucose or the xylose was the substrate When the glucose was substrate,the...The glucose isomerase(GI) was a metal activating enzyme It was most activated by Co 2+ and Mg 2+ ,and Mg 2+ was the best activator,whether the glucose or the xylose was the substrate When the glucose was substrate,the dissociation constant of Mg 2+ GI,Co 2+ GI and Mn 2+ -GI was 115 μmol/L,40 μmol/L, and 15 μmol/L respectively. The maximum activity of Mg 2+ GI,Co 2- GI and Mn 2+ GI was 100%,85%,and 20% respectively. When the xylose was substrate,the order of dissociation constant and maximum activity of the metal enzymes was the same Ca 2+ was a competitive inhibitor versus Mg 2+ ( K i 7 4 μmol/L)or Co 2+ ( K i 99 μmol/L). Compared with Mg 2+ GI,the K m of Co 2+ GI was more,and the V M of Co 2+ GI less The process of activity recovery from apo GI to metal GI showed that it was slow and of two展开更多
基金Funded by the National Natural Science Foundation of China(Nos.50972041,61274010)Program for New Century Excellent Talents in University,Ministry of Education of China(No.NCET-09-0135)+2 种基金Research Fund for the Doctoral Program of Higher Education of China(Nos.20124208110005,20124208120006)the Natural Science Foundation of Hubei Province(No.2011CDA81)Science Foundation of Hubei Provincial Department of Education(No.D20131001)
文摘Divalent IIA metals such as Be, Mg, Ca, Sr, Ba and transition IIB metals such as Zn, Cd were investigated as possible n-type dopants into the Cu2 O theoretically by using the first-principles calculations based on density functional theory. By systematical analyses of the lattice parameters, the bond length, the electronic structure, the local density of states and the defect formation energy for various doping systems, it is revealed that Ca, Sr, Ba and Be are more suited for n-type doping into Cu2O as shallow donors, compared to Mg which introduces a relatively deep donor level in Cu2O. Meanwhile, Zn and Cd can hardly be doped into Cu2O due to the positive formation energy of relevant defects.
文摘The solvent extraction process combined with tools of experimental design assists in developing procedures for separation and purification of elements or mineral compounds with high purity. In this work the technique was used to replace the traditional methods for the collection of basic information required for the development of a circuit of solvent extraction. According to the literature, several factors may influence the extraction of divalent metals by D2EHPA in sulfate media, among which the concentration of metals in solution. The objective was to study the variables affecting the separation process Mn/Ni/Co/Cu, such as the aqueous/organic (A/O), contact time, concentrations of the divalent metals in sulfuric medium, pH and solvent concentration. An investigation into the variables that control the process was done using a “cube + star” experimental design, with central point. The results demonstrate it is possible to obtain of a satisfactory mathematical model that describes the process.
文摘目的研究巴罗沙星与 DNA 的分子作用机制和 Mg^(2+)对巴罗沙星与 DNA 相互作用的影响。方法利片J荧光光谱研究巴罗沙星与 DNA 的作用强度并计算热力学数据ΔH;利用紫外光谱、黏度测定、竞争实验、与变性 DNA作用的比较等方法确定巴罗沙星与小牛胸腺 DNA 的相互作用方式;利用荧光光谱考察 Mg^(2+)对巴罗沙星与小牛胸腺DNA 相互作用的影响。结果 DNA 对巴罗沙星的荧光猝灭常数为(5.43±0.07)×10~3L·mol^(-1),ΔH=-8.03 kJ·mol^(-1);Mg^(2+)使巴罗沙星与 DNA 的作用增强。结论巴罗沙星以沟槽键合方式与 DNA 相瓦作用;Mg^(2+)对巴罗沙星与 DNA 的结合有中介作用。
文摘The glucose isomerase(GI) was a metal activating enzyme It was most activated by Co 2+ and Mg 2+ ,and Mg 2+ was the best activator,whether the glucose or the xylose was the substrate When the glucose was substrate,the dissociation constant of Mg 2+ GI,Co 2+ GI and Mn 2+ -GI was 115 μmol/L,40 μmol/L, and 15 μmol/L respectively. The maximum activity of Mg 2+ GI,Co 2- GI and Mn 2+ GI was 100%,85%,and 20% respectively. When the xylose was substrate,the order of dissociation constant and maximum activity of the metal enzymes was the same Ca 2+ was a competitive inhibitor versus Mg 2+ ( K i 7 4 μmol/L)or Co 2+ ( K i 99 μmol/L). Compared with Mg 2+ GI,the K m of Co 2+ GI was more,and the V M of Co 2+ GI less The process of activity recovery from apo GI to metal GI showed that it was slow and of two
