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An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Four samples of hyaluronan in the sodium form, ranging in weight-average molecular weight, Mw, from 6.67 × 105 to 4.23 × 106 were investigated by asymmetrical-flow field-flow fractionation coupled to multiangle light scattering (FlFFF−MALS) in 0.2 M aqueous NaCl at 25 °C. Mw and z-average radii of gyration, RGz, obtained via FlFFF−MALS showed a good agreement with the results obtained by conventional static light scattering. Furthermore, the molecular weight dependence of the radius of gyration for sodium hyaluronan obtained via FlFFF−MALS was analyzed on the basis of the Kratky−Porod model for unperturbed wormlike chains combined with the Yamakawa theory for radius expansion factor, and a sufficiently good agreement was observed between the theoretical prediction and experimental data. These results show the potential usage of FlFFF−MALS regarding size separation and molecular characterization even for weakly stiff chains.
The shear and extensional viscosity characteristics have been compared for hyaluronan and two samples of a cross-linked derivative, hylan, of different molecular weights. While shear thinning behavior was observed for all systems in shear flow, strain thickening was observed in extensional flow for the relatively dilute systems. However, there was a progressive transition to shear thinning behavior as the polymer concentration was increased. It is evident from the results that the shear flow techniques alone provide an incomplete picture of the rheological properties of these materials and that extensional flow characteristics are potentially dominant. For example, at relatively high deformation rates of 500 s-1 and above, our results show that the extensional viscosities of aqueous solutions of the various polymers are at least two orders of magnitude greater than their corresponding shear flow viscosities. The incremental differences in viscosity with concentration increased with increasing molecular mass of the polymers and were greater in exensional flow than shear flow. These results demonstrate that the dynamic network structure formed by the higher molecular mass hylans offer potentially better physical and mechanical properties for viscosupplementation of diseased osteoarthritis joints compared with the parent hyaluronan.
Studies on chemical pulping physico-chemical model of necephilic sulphiting in the processes of wood delignification photophysical and photochemical properties of lignin chromophores new bleach sequences of Kraft pulse using hemicellulases physico-chemical properties of pine dead wood tree foliage as a source of chemical and feeding components new functionalized cellulosic materials - synthesis, properties, applications wood protection lignolytic peroxidases of white-rot fungi utilization of the products of polyose thermal degradation as surfactants structure and reactivity of beech sulphite pulps production of defined cellulose crystallites from cotton fibres by a cellulase complex from trichoderma reesei modification of lignin and its structure application of cellulose and cellulose derivatives for drug modification production of oxalic acid from plant fibres by catalytic oxidation.
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