Iranian Journal of

---

Background and Objectives: Aydughmush dam was built on Aydughmush River at 19km in southwest of Mianeh City. The dam is multipurpose and its main aims are the spring floods control, supplying potable water for villages and providing irrigation water. Different pollutants which probably discharge to the river finally enter to the dam reservoir so this study focuses on evaluating the quality of the dam reservoir.
Materials and Methods: In this cross sectional study standard field parameters including dissolved oxygen, temperature, Biochemical and chemical oxygen Demand, Most Probable Number of Coliforms, Fecal Coliform, Turbidity, Total Dissolved Solids, Total Solids, pH, conductivity and others were measured at eight different stations during the spring and summer in 2010. Sampling points were selected on the basis of their importance. Water quality index was calculated using water quality index calculator given by National Sanitation Foundation (NSF) information system.
Results: The highest value of WQI of the samples was 84.89 in A3 station in July while the lowest value was 67.96 in A2 station in May. The lower value of WQI has been found mainly due to the slightly lower value of DO in the dam reservoir water. Most of the water samples were found within Good category of National Sanitation Foundation Water Quality Index (NSF-WQI). Comparison of the measured parameters based on the sampling stations and  various months by variance and t-student analysis showed a significant relationship for some parameters(P<0.05). Nutrient budget determination indicates that the concentration of phosphate, nitrite, nitrate and ammonia at inlet are higher than outlet of the dam reservoir.
Conclusion: The calculated (WQI) showed good water quality. Based on the results of NSFQWI calculations, the dam reservoir water quality is suitable for various purposes.

---

MicrosoftInternetExplorer4 Background and Objectives: Along with the rapid development of human life, controlling   harmful effects of microorganisms would be unavoidable. The objective of this study was to evaluate antibacterial efficacy of zinc oxide nanoparticles on different microbial strains.
Material and Methods: This experimental study was done using gram negative and gram positive bacteria in nutrient media. Nanoparticle characterization was determined using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM). Bacterial sensitivity to nanoparticles was tested using a disk diffusion test and minimum inhibitory concentration (MIC). Time-kill studies and other tests were carried out using 108 CFU/mL of bacteria at baseline. A point of zero charge, pHzpc, of nanoparticle was investigated using the batch equilibration method. Obtained data were managed by SPSS Ver.16 and were analyzed through the Pearson, analysis of variance (ANOVA) and Student's independent t-tests. 0.05 was selected as significant level for all tests.
Results: Characterization results from XRD, SEM, and TEM showed that particles are in nano range and they do not contain any discernible crystalline impurity. The average ZnO nanoparticles diameter was 20 nm. The pHZPC for ZnO was found to be 7.51. The P. aeruginosa strain exhibited larger diameter inhibition zone (DIZ) to ZnO nanoparticle compared with other strains. Population of P.aeroginosa for 2 x MIC concentration was reduced to zero in the presence of nano ZnO within 150 min. The bacterial CFU had significant difference with contact time, nanoparticles loading, and bacterial strain (P<0.001).
Conclusion: This study demonstrated that antibacterial activity of ZnO can be a candidates for the elimination of gram negative and gram positive bacteria, particularly in nasocomial infection agent control.