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Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D2O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 A. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10-5 cm²/sec. [ABSTRACT FROM AUTHOR]

Microspheres of silica having an average diameter of 20μ have been compacted and sintered at 640° C for 3 hrs, 6 hrs and 24 hrs according to an established schedule. The characterization of these porous materials using Scanning Electron Microscopy (SEM), Ultra Small Angle Neutron Scattering (USANS), and density measurements by water displacement is reported here. The SEM micrographs show a variation of pore sizes of widths 2 μ-20 μ and lengths 2 μ-60 μ. Ultra SANS data indicate a fractal-like agglomerate structure within these compacts from the power law behavior of scattered intensity over a wide wave vector transfer range. [ABSTRACT FROM AUTHOR]

Nickel oxide nanopowder was synthesized by sol gel method using nickel nitrate as the starting material. Nickel oxide nanoparticles with a grain size of 15-90 nm have been studied by; small angle neutron scattering; scanning electron microscopy; and vibrating sample magnetometry. A combination of Ferro and paramagnetic behaviour of the particles after calcination at 800 °C is observed while for powder calcined at 400 °C, soft magnetic character with saturation is seen. The system of nanoparticles ofNiO embedded in a silica matrix is also studied for the structural change. Weak magnetic ordering is observed in this case with the likely-hood of particles being evenly distributed in the silica. [ABSTRACT FROM AUTHOR]