Polymer blend electrolytes composed of poly(vinylidene fluoride-co-hexafluoro-propylene), poly(methyl methacrylate) and 1•0 M NaI as salt have been synthesized using solution caste technique by varying the PVdF(HFP)-PMMA blend concentration ratio systematically. A.c. impedance studies were performed to evaluate the ionic conductivity of the polymer electrolyte films. The highest ionic conductivity at room temperature for [PVdF(HFP)-PMMA(4:1)](20 wt%)-[NaI(1•0 M)](80 wt%) system is found to be 1•67 × 10 −2 S cm −1. XRD studies reveal complete complexation of the salt in the polymeric blend systems. The temperature dependence conductivity has been performed in the range of 303-373 K and it is observed that it obeys the Arrhenius behaviour. It has been observed that the dielectric constant, ε r and dielectric loss, ε i , increases with temperature in the lower frequency region and is almost negligible in the higher frequency region. This behaviour can be explained on the basis of electrode polarization effects. Plot of real part, M r and imaginary part, M i vs frequency indicates that the systems are predominantly ionic conductors. The phenomenon suggests a plurality of relaxation mechanism.

The inverting O-GlcNAc glycosyltransferase (OGT) is an important post-translation enzyme, which catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine (UDP-GlcNAc) to the hydroxyl group of the Ser/Thr of cytoplasmic, nuclear, and mitochondrial proteins. In the past, three different catalytic bases were proposed for the reaction: His498, α-phosphate, and Asp554. In this study, we used hybrid quantum mechanics/molecular mechanics (QM/MM) Car-Parrinello molecular dynamics to investigate reaction paths using α-phosphate and Asp554 as the catalytic bases. The string method was used to calculate the free-energy reaction profiles of the tested mechanisms. During the investigations, an additional mechanism was observed. In this mechanism, a proton is transferred to α-phosphate via a water molecule. Our calculations show that the mechanism with α-phosphate acting as the base is favorable. This reaction has a rate-limiting free-energy barrier of 23.5 kcal/mol, whereas reactions utilizing Asp554 and water-assisted α-phosphate have barriers of 41.7 and 40.9 kcal/mol, respectively. Our simulations provide a new insight into the catalysis of OGT and may thus guide rational drug design of transition-state analogue inhibitors with potential therapeutic use.

The physico-chemical aspects of the order–disorder phase transitions occurring in the Na2SO4–Ag2SO4 system were investigated by thermal analyses, X-ray diffraction, and electrical conductivity techniques. Electrical conductivity data on pure and doped compositions reveal high conductivity values in the high temperature phase.The lower conductivity of Ag2SO4 with Na+ presence relative to pure Ag2SO4 is attributed to lattice contraction effecting lower mobility of ions.