Immobilization of β-galactosidase onto polymeric supports

Poly(vinyl alcohol) cross-linked with para-formaldehyde (PVA–F) and natural polysaccharide–chitosan in bead form and salicylic acid–resorcinol–formaldehyde polymeric resin (SRF) in powder form were used for immobilization of β-galactosidase through covalent linkages. Various activation processes and conditions were optimized. Immobilized enzyme showed very good storage stability at room temperature. Durability of the enzyme was also improved on immobilization. On repeated use of enzyme immobilized on chitosan beads, no loss was observed in enzyme activity even after 10 batches. Michaelis constant K_m and maximum reaction velocity V_m were calculated for free and immobilized enzyme systems. Effect of pH and temperature on enzyme activity was estimated and energy of activation (E_a) and inactivation constant (K_i) for free and immobilized enzyme were calculated. © 1995 John Wiley & Sons, Inc.     

The role of cognitive complexity and risk aversion in online herd behavior

Electronic Commerce Research - This paper investigated the role of information related, social and customer characteristics in public information adoption tendencies of online customers to result...     

Optical studies on Eu/ZnSe nanocrystal in silica hosts

The wide band gap semiconductor zinc selenide nanocrystallites together with europium ions were incorporated into the silica matrix using sol–gel method. The size distribution and optical band gap of the nanoparticles were calculated from the absorption spectrum. The TEM measurements yield the nanocrystal size to be around 6 nm and a crystal inter planar spacing to be 3.278 Å. The excitation spectra recorded for the sample gives a broad excitonic band around 370 nm which could be assigned to the ZnSe nanocrystallites. The fluorescence spectra reveal that the intensity of characteristic emission of europium increases considerably in the presence of ZnSe particles.