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Biomedical subjects

I M Talwar

Publications and source records attributed to I M Talwar.

4 recordsLinked to original sources
PubMed1991

Thermally stimulated polarization studies of kidney stones. II. Effect of annealing and thickness.

To investigate the cause of the d.c. charged conductivity state of kidney stones, the effect of annealing and sample thickness on thermally stimulated polarization was studied. It was observed that the peak current decreased and the peak temperature rose with increasing annealing temperature and the sample thickness. The sharpness of the single peak decreased and the activation energy increased with both parameters. The results have been explained on the basis of the loss of water attached to calcium oxalate and calcium phosphate, denaturation of collagen and the ionic nature of the main constituents of the kidney stone.

Calcium↗
PubMed1989

Electrical conductivity of kidney stones.

Electret behaviour of surgically removed kidney stones through thermally stimulated polarization and thermally stimulated depolarization has already been reported by the authors. To develop an understanding of the conduction mechanism of such samples, d.c. conductivity was studied as a function of temperature and electric field. Temperatures from 308 to 448 K and fields from 0.5 X 10(6) to 2.5 X 10(6) V/m were used on the compressed powder pellet of a kidney stone. Conductivity was found to be 6 X 10(-11) s/m to 1.0 X 10(-11) s/m in the studied temperature range. Possibility of semiconduction is shown and it is suggested that kidney stone is a partially compensated semiconductor of n-type. The field independence of conductivity is observed at higher temperatures. The slopes of current density versus field curves suggest a warm electron effect.

Electric Conductivity↗
PubMed1987

The electret effect of kidney stones.

Surgically removed kidney stones were powdered and samples made from them were subjected to a d.c. field of 20-50 kV/cm whilst being heated at 1 degree C/min. The thermally stimulated polarization (TSP) spectrum obtained showed the dipolar nature of the material. Dipolar polarization in the stones was confirmed by other experiments.

Electrochemistry↗