Islamic Azad University

About: Islamic Azad University is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Population & Adsorption. The organization has 83635 authors who have published 113437 publications receiving 1275049 citations. The organization is also known as: Azad University.

Groundwater qanat potential mapping using frequency ratio and Shannon’s entropy models in the Moghan watershed, Iran

Abstract: The purpose of current study is to produce groundwater qanat potential map using frequency ratio (FR) and Shannon's entropy (SE) models in the Moghan watershed, Khorasan Razavi Province, Iran. The qanat is basically a horizontal, interconnected series of underground tunnels that accumulate and deliver groundwater from a mountainous source district, along a water- bearing formation (aquifer), and to a settlement. A qanat locations map was prepared for study area in 2013 based on a topographical map at a 1:50,000-scale and extensive field surveys. 53 qanat locations were detected in the field surveys. 70 % (38 locations) of the qanat locations were used for groundwater potential mapping and 30 % (15 locations) were used for validation. Fourteen effective factors were considered in this investigation such as slope degree, slope aspect, altitude, topographic wetness index (TWI), stream power index (SPI), slope length (LS), plan curvature, profile curvature, distance to rivers, distance to faults, lithology, land use, drainage density, and fault density. Using the above conditioning factors, groundwater qanat potential map was generated implementing FR and SE models, and the results were plotted in ArcGIS. The predictive capability of frequency ratio and Shannon's entropy models were determined by the area under the relative operating characteristic curve. The area under the curve (AUC) for frequency ratio model was calculated as 0.8848. Also AUC for Shannon's entropy model was 0.9121, which depicts the excellence of this model in qanat occurrence potential estimation in the study area. So the Shannon's entropy model has higher AUC than the frequency ratio model. The produced groundwater qanat potential maps can assist planners and engineers in groundwater development plans and land use planning.

Theoretical study of aluminum nitride nanotubes for chemical sensing of formaldehyde

Abstract: Semiconductive carbon nanotubes (CNTs) have demonstrated great sensitivity toward molecules such as NH3, NO, and NO2. Nevertheless, pristine CNTs cannot be used for detection of some highly toxic molecules such as formaldehyde (HCOH). In the present study, we examined the possibility of using aluminum nitride nanotubes (AlNNTs) as a potential gas sensor for HCOH detection by performing density functional theory (DFT) calculation. It was found that HCOH molecule can be chemisorbed on the surface of AlNNTs with Gibbs free energies of −0.59 to −0.64 eV, at standard temperature and pressure (STP, 1 atm and 298 K). In view of the high change of HOMO/LUMO energy gap of the tube during the chemisorption, it is expected that the process induce a significant change in its electrical conductivity. Hence, the AlNNT can be used as a potential efficient gas sensor for HCOH detection. Furthermore, it was shown that H2O molecules cannot significantly change the electronic properties of AlNNTs.