Extensive DFT calculations are performed to optimize the geometric structures of O-rich tungsten oxide clusters, to simulate the PES spectra, and to analyze the chemical bonding. The ground-state structure of W4O14^- ...Extensive DFT calculations are performed to optimize the geometric structures of O-rich tungsten oxide clusters, to simulate the PES spectra, and to analyze the chemical bonding. The ground-state structure of W4O14^- is best considered as W4O12（O2^-）, containing a side-on bound superoxide ligand. The current study indicates that the extra electron in W4O12^- is capable of activating dioxygen by non-dissociative electron transfer （W 5d → O2 π^＊）, and the anionic clusters can be viewed as models for reduced defect sites on tungsten oxide surfaces for the chemisorption of O2.展开更多
Objective To explore the protective effects of N Acetylcysteine (NAC) on exogenous hydrogen peroxide and endogenous superoxide anion induced DNA strand breakage in human spermatozoa by using the single cell gel el...Objective To explore the protective effects of N Acetylcysteine (NAC) on exogenous hydrogen peroxide and endogenous superoxide anion induced DNA strand breakage in human spermatozoa by using the single cell gel electropherosis (SCGE) Methods Sperm cells were exposed to 0.5 mmol/L of H 2O 2 or 5.0 mmol/L of β NADPH with or without 0.1, 0.5, 1.0 mmol/L of NAC. The percentage of sperm comet cells and the comet tail lengths were measured in the treated sperm cells by using SCGE. Results Both percentage of comet sperm nuclei and mean tail length in sperm cells exposed to 0.5 mmol/L hydrogen peroxide with different concentrations of NAC decrease significantly in a dose dependent manner as compared with sperm cells exposed to H 2O 2 without NAC or catalase. Although mean tail length in sperm cells exposed to 5.0 mmol/L of β NADPH with different concentrations of NAC decreases significantly compared with sperm cells exposed to β NADPH without NAC or SOD, there were no significant differences on the percentage of sperm comet cells between sperm cells exposed to 5.0 mmol/L of β NADPH with different concentrations of NAC and sperm cells exposed to 5.0 mmol/L of β NADPH without NAC. Conclusion NAC has a protective effect on exogenous hydrogen peroxide induced DNA damage, while protective effect of NAC against O - 2 induced DNA strand breakage is significant but very weak.展开更多
基金the National Natural Science Foundation of China (20641004, 20771026 and 20773024)the Natural Science Foundation of Fujian Province (No. 2008J0151)
文摘Extensive DFT calculations are performed to optimize the geometric structures of O-rich tungsten oxide clusters, to simulate the PES spectra, and to analyze the chemical bonding. The ground-state structure of W4O14^- is best considered as W4O12（O2^-）, containing a side-on bound superoxide ligand. The current study indicates that the extra electron in W4O12^- is capable of activating dioxygen by non-dissociative electron transfer （W 5d → O2 π^＊）, and the anionic clusters can be viewed as models for reduced defect sites on tungsten oxide surfaces for the chemisorption of O2.
基金China Medical Board ( 980 0 1 ) and Natural Science Foundation ofAnhui Province( 99j1 0 0 95)
文摘Objective To explore the protective effects of N Acetylcysteine (NAC) on exogenous hydrogen peroxide and endogenous superoxide anion induced DNA strand breakage in human spermatozoa by using the single cell gel electropherosis (SCGE) Methods Sperm cells were exposed to 0.5 mmol/L of H 2O 2 or 5.0 mmol/L of β NADPH with or without 0.1, 0.5, 1.0 mmol/L of NAC. The percentage of sperm comet cells and the comet tail lengths were measured in the treated sperm cells by using SCGE. Results Both percentage of comet sperm nuclei and mean tail length in sperm cells exposed to 0.5 mmol/L hydrogen peroxide with different concentrations of NAC decrease significantly in a dose dependent manner as compared with sperm cells exposed to H 2O 2 without NAC or catalase. Although mean tail length in sperm cells exposed to 5.0 mmol/L of β NADPH with different concentrations of NAC decreases significantly compared with sperm cells exposed to β NADPH without NAC or SOD, there were no significant differences on the percentage of sperm comet cells between sperm cells exposed to 5.0 mmol/L of β NADPH with different concentrations of NAC and sperm cells exposed to 5.0 mmol/L of β NADPH without NAC. Conclusion NAC has a protective effect on exogenous hydrogen peroxide induced DNA damage, while protective effect of NAC against O - 2 induced DNA strand breakage is significant but very weak.
