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 & Catalysis. The organization has 83635 authors who have published 113437 publications receiving 1275049 citations. The organization is also known as: Azad University.

Numerical simulation of natural convection heat transfer inside a ┴ shaped cavity filled by a MWCNT-Fe3O4/water hybrid nanofluids using LBM

Abstract: Natural convection of multi-wall carbon nanotubes-Iron Oxide nanoparticles/water hybrid nanofluid (MWCNT-Fe 3 O 4 /water hybrid nanofluid) inside a ┴ shaped enclosure has been numerically investigated using Lattice Boltzmann Method. Numerical in-house code has been developed to study the effects of different parameters including the nanoparticles volume fraction, the Rayleigh number, the cavity obstruction ratio, the heat source position, and the heat source aspect ratio on the hydrodynamic and thermal characteristics. In order to validate the developed numerical code, the results have been compared with previous works and have shown a good concordance. The results indicate that Nusselt number degrades respect to the cavity obstruction ratio because of development of the thermal boundary layer thickness. In addition, an increment of the heat source aspect ratio results in better cooling condition due to decreasing in the boundary layer thickness.

Effect of cationization on adsorption of silver nanoparticles on cotton surfaces and its antibacterial activity

Abstract: Cotton was cationized by exhaustion method using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) as a cation-generating agent. Adsorption of silver nanoparticles on normal and cationized cotton was studied by exhaustion method at temperatures of 80°C and 100°C. Two exhaustion baths were used, containing nanosilver colloidal solutions stabilized by two different stabilizers and various concentrations of silver nanoparticles. Fourier-transform infrared (FT-IR) spectra of normal and cationized samples confirmed the existence of quaternary ammonium groups on cationized cellulose fibers. X-ray diffraction (XRD) patterns showed that crystallinity of the modified cellulose fibers was decreased. Scanning electron microscope (SEM) images revealed that the surface of the modified cotton was rougher than that of normal cotton. In addition, SEM images showed the presence of silver nanoparticles on the surface of treated fabric samples. The amount of silver particles adsorbed on the fabric samples was determined using inductively coupled plasma-optical emission spectrometer. Antibacterial tests were performed against Escherichia coli bacteria as an indication of antibacterial effect of samples. Cationized cotton samples adsorbed more silver nanoparticles and then had greater ability to inhibit bacteria.