Thermal Expansion and Superconductivity in Alkali Metal- and Silver-doped Bi?Sr?Ca?Cu?O System

Samples with the nominal composition Bi₂Sr₂CaCu₂O_y with na doped at the Ca site and K doped at the Sr site are prepared by solid state reaction method. From the X-ray diffraction data it is found that all the the samples have exhibited a single phase 2212. The D.C. electrical resistivity data show that for Na-doped samples the T_c (zero) varies from 80 K to 85 K and for K-doped samples it is from 79 K to 82 K. The loss of oxygen from these samples around 400°C was confirmed by high temperature dilatometry. The variation of the thermal expansion coefficient (“α”) with temperature for different alkali dopings are discussed. Also the samples with the nominal composition Bi₄Sr₃Ca₃Cu_4−xAg_xO_y (with x = 0, 0.1, 0.2, 0.3) were studied.     

Application of p-N,N-dimethylphenylenediamine dihydrochloride for the determination of some diuretics

A spectrophotometric method is described for the determination of acetazolamide, frusemide, polythiazide, benzthiazide, hydrochlorothiazide, hydroflumethiazide, trichlormethiazide and amiloride hydrochloride (AML) either in pure form or in pharmaceutical formulations. The method is based on the reaction with p-N,N-dimethylphenylenediamine dihydrochloride and chloramine-T, to give a coloured product having maximum absorbance at 660 nm (for AML) or at 540 nm for the others, and reproducible within +/- 1.0%.     

Some remarks on good sets

It is shown that (1) if a good set has finitely many related components, then they are full, (2) loops correspond one-to-one to extreme points of a convex set. Some other properties of good sets are discussed.