Mineralogy of agricultural soil of selected regions of South Western Karnataka, Peninsular India.

Agricultural soils of selected regions of Southwestern Karnataka, Peninsular India, were subjected to systematic mineralogical characterization along with the study of soil physical properties. Physical properties such as soil texture and micro porosity were studied using particle size analyses and positron annihilation lifetime analysis (PALS) technique, respectively. The latter was used to analyze micro porosity of agricultural soil.

Influence of polar groups in binary polymer blends on positronium formation.

The present work studied the role of the polar group unconjugated oxygen on the inhibition of positronium (Ps) formation in two binary blends made from a set of chosen constituent polymers with polar and weakly polar groups (nonpolar). The polymer blend samples of PVC-EVA and PVC-SAN were investigated by coincidence Doppler broadening and positron lifetime techniques. The strong polar acetate group in the EVA contributed to positron annihilation with electrons of unconjugated oxygen (-C(+)=O(-)) as revealed by the momentum distribution curves peaking around 17 P(L) (10(-3) m(0)c).

Chemical and photochemical degradation of human hair: a free-volume microprobe study.

The microstructural changes in human hair due to chemical and photochemical oxidative processes have been monitored in terms of free volume employing Positron Annihilation Lifetime Spectroscopy (PALS). The results show that upon UV exposure the photosensitive amino acid residues present in the amorphous domains of virgin/bleached hair cross-link under ambient conditions. Further, the bleached hair readily undergoes photodamage in comparison with the virgin hair implying the diminished photoprotective action of the melanin granules within it.

Diffusion of permanent liquid dye molecules in human hair investigated by positron lifetime spectroscopy.

The diffusion behavior of a commercial permanent liquid hair dye in human hair has been investigated using positron annihilation lifetime spectroscopy (PALS) and gravimetric sorption method. The positron technique makes it possible to non-invasively characterize the angstrom sized free volume holes in hair, which are supposed to be express pathways for diffusion of small molecules. The o-Ps lifetime parameters tau3 and I3 decrease rapidly during the first 60 min of sorption time.

Influence of spoliation in poly(2-hydroxy ethyl methacrylate) soft contact lens on its free volume and optical transparency.

The calcification in poly(2-hydroxy ethyl methacrylate) contact lens was investigated using positron annihilation spectroscopy (PLS). The two poly(2-hydroxy ethyl methacrylate) (PHEMA) lenses of different companies were calcified employing a simple mechanism of calcification in abiotic aqueous solutions. The calcium deposit was analyzed using energy dispersive X-ray spectroscopy (EDS).