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Molecular dynamics approach accompanied by reactive force field is used to study the characteristics of the oxide growth process on Ni(100) and Ni(111) surfaces at the temperatures of 300, 600, and 900 K and 5 eV as the energy of the O2 impacts. The exposure of Ni surfaces to the high-energy O2 impacts indicates that the primary oxide nuclei can be formed on any impact site. The results of kinetic studies clarify that the oxide growth kinetics cannot be accurately explained with the island growth model and increasing the surface temperature raises failure of the model. Under the present conditions, the growth kinetics is found to obey a Langmuir growth model. Increasing the surface temperature from 300 to 900 K results in !18.75% and ~23% more oxygen consumption by (100) and (111) surfaces of Ni, respectively. The structure of nickel oxide (NiO) film formed after 200 successive O2 impacts per surface super-cell is investigated utilizing radial distribution functions and oxygen density profiles. These calculations demonstrate that the structure of the formed NiO film is amorphous. Moreover, the charge profiles in Ni/NiO system are illustrated and discussed. [ABSTRACT FROM AUTHOR]

In current study, a two-stage aerobic sequencing batch reactor (SBR) at laboratory scale was used to investigate the removal of chemical oxygen demand (COD) of a soft drink factory wastewater. The experiment was settled in series and has been combined with ozonation unit as a middle step. We evaluated the effect of three significant independent variables on the process including: mixed liquor suspended solids in both SBRs (MLSS1 and MLSS2) and feed-gas/off-gas ozone concentrations. MLSS was limited to the 3,000, 4,500, and 6,000 mg/L, for both SBRs. Central composite design matrix (CCD) was used for the experimental design and response surface methodology (RSM) was employed to optimize the experiments. The results showed that using ozonation as a middle stage between two-stage SBR significantly affects COD removal of the soft drink factory effluent. In addition, multistage biological process revealed that MLSS in the first-stage SBR (i.e. MLSS1) influences the COD removal efficiency. We also found that due to a reduction in organic matter of effluent in first SBR, MLSS in the second stage SBR (MLSS2) is less important than MLSS1. Maximum COD removal efficiency (up to 95%) was obtained for the following conditions: MLSS1 6,000 mg/L, MLSS2 4,500 mg/L, and employing ozone. Based on a very good matching between predicted values of the RSM model and the experimental values (R² = 0.989 and Adj-R² = 0.981), we suggest that our model can be considered for future optimization of the COD removal. [ABSTRACT FROM AUTHOR]

Background: The purpose of the present study was to investigate physical activity by socioeconomic status (SES) and sex in an Iranian adult population., Methods: In a cross-sectional study, 6622 adults, who participated in the Isfahan Healthy Heart program (IHHP) surveys in 2004 and 2005 and were living in urban areas, were studied. Daily leisure time, household, occupational, and transportation physical activity, and total physical activity were calculated and compared in 3 socioeconomic status groups classified by the two-step cluster analysis procedure., Results: Statistically significant variations were found in all physical activity levels, except transportation, by sex. Men were more active than women in all fields, except household physical activity. Leisure time physical activity of men and women were significantly higher in higher SES levels. There was an opposite correlation between SES and total physical activity in men., Conclusion: Considering the importance of physical activity as a component of a healthy lifestyle, differences among varying socioeconomic status and sex must be considered while planning for healthy lifestyle programs. Women with low SES, in particular, may need more attention.