Sharif Digital Repository

In this study, Lipase from Aspergillus Niger after extraction of medium culture was precipitated with different percentages of acetone and purified by ion exchange chromatography using SP-Sepharose HP and Q-Sepharose HP. The process of purification of the enzyme was studied by electrophoresis and the molecular weight was detected and determined by Zymography using overlying containing phenol red and Rhodamine B. The results showed that the vast majority of lipase from this strain has been precipitated by 70% saturation acetone, and leads to the 1.67 fold the purified enzyme, with special activities 32.8 U. mg-1 and efficiency of 38.5%. Using two-phase chromatography, enzyme specific activity... 

Copper-palladium alloys of different compositions are electrodeposited on nickel from aqueous solutions. These alloys are characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The catalytic activity of these alloys toward oxygen reduction reaction (ORR) in alkaline solution is investigated using rotating disk electrode (RDE). The number of electrons transferred per O2 molecule (n) obtained at different potentials is close to 2 at low overpotential indicating HO2- formation and gradually increases to 4 at higher overpotentials indicating full reduction to OH-. It is shown that Cu-Pd alloys are better electrocatalysts than Pd with Pd-Cu-1 having 24.5%... 

In this paper, the effect of ozone on membrane fouling of membrane bioreactor (MBR) systems was investigated. Sludge specification such as soluble microbial product (SMP), extracellular polymeric substance (EPS), viscosity, particle size distribution (PSD), microscopic observations and sludge volume index (SVI) in presence of ozone were determined. Further, EPS, Fourier-transform infrared (FTIR) analysis, excitation-emission matrix (EEM) fluorescence spectroscopy, and gel permission chromatography (GPC) are considered to determine cake layer characteristics. The results indicated COD removal did not show significant difference with ozonation. Ozone also increases the particle size and...