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Mishra A.K.,Indian Institute of Chemical Technology | Narayan R.,Indian Institute of Chemical Technology | Pradhan S.K.,Institute of Minerals and Materials Technology formerly Regional Research Laboratory | Raju K.V.S.N.,Indian Institute of Chemical Technology
Journal of Applied Polymer Science | Year: 2012

Hyperbranched polyurethane-urea-imide/o-clay-silica (HBPUI/o-clay-silica) hybrid coatings were prepared using organically modified clay (o-clay) in the presence of cetyltrimethylammonium bromide (CTAB) and tributylhexadecylphosphonium bromide (TBHPB) cationic surfactants and were further surface-grafted by 3-aminopropyltrimethoxy silane (APTMS). Hybrid polyesters were prepared by incorporating into the first generation hyperbranched polyester polyol (HBP-G1) at various concentrations. The NCO-terminated hybrid prepolymers and chain extensions were achieved by imide chain extender. The modified clays were characterized by powder X-ray diffraction and Fourier transform spectroscopy. Viscoelastic, thermomechanical, and surface topology studies were performed by dynamic mechanical thermal analysis (DMTA), thermogravimetric analyser (TGA), universal testing machine (UTM), atomic force microscopic (AFM), and contact angle measurements. TGA and DMTA indicated higher thermal stability and glass transition temperature (T g) of TBHPB-modified hybrid coatings compared with the CTAB counterparts, which increased with increasing silane-modified o-clay content. Water contact angle suggested increasing hydrophobicity of higher silane-modified o-clay containing coatings, while AFM confirmed the dispersibility of silane-modified o-clay into polymer matrix; the extent of dispersion increased with increasing silane-modified o-clay content in the hybrid formulation. © 2011 Wiley Periodicals, Inc. Source

Baral M.,Institute of Minerals and Materials Technology formerly Regional Research Laboratory | Misra N.,Institute of Minerals and Materials Technology formerly Regional Research Laboratory | Panda P.K.,Institute of Minerals and Materials Technology formerly Regional Research Laboratory | Thirunavoukkarasu M.,Institute of Minerals and Materials Technology formerly Regional Research Laboratory
Biotechnology and Biotechnological Equipment | Year: 2012

Glycerol-3-phosphate acyltransferase (GPAT) is an enzyme in the triacylglycerol (TAG) biosynthetic pathway that catalyses the conversion of glycerol-3-phosphate to lysophosphatidic acid. Targeting key enzymes involved in TAG pathway is considered to be a powerful strategy for augmented lipid accumulation in microorganisms. In the present study three-dimensional structure of the marine microalgae, Ostreococcus lucimarinus GPAT protein was developed based on the crystal structure of Cucurbita moschata GPAT protein. Besides, several structure validation tools were employed to confirm the reliability of the developed model. The predicted and validated model reveals the tertiary structure of GPAT monomer comprising of two domains, the smaller domain I, which folds into a four helix bundle, and the larger domain II, which is constructed from alternating α/β secondary structural elements that give rise to 9-stranded β sheet flanked by 11α helices. Critical structural analysis of the developed model reveals the presence of H(X) 4D motif; the latter being, a consensus sequence conserved amongst many glycerolipid acyltransferase. The detected cluster of positively charged residues H 189, K 243, H 244, R 285 and R 287 in the model could be conjectured to be important in glycerol-3-phosphate recognition. The structural insight obtained from this in silico study may provide useful clues to further advanced biotechnological studies of strategic site-specific genetic and metabolic engineering of microalgae for enhanced biofuel production. Source

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