Quadrature formulas obtained by variable transformation

Quadrature formulas suitable for evaluation of improper integrals such as are obtained by means of variable transformations =tanhu and =erfu, and subsequent use of trapezoidal quadrature rule. Error analysis is carried out by the method of contour integral, and the results are confirmed on several concrete examples. Similar formulas are also obtained to accelerate the convergence of infinite integrals by means of variable transformations =sinhu and =tanu.     

Spectrophotometric determination of biologically active thiols with eosin, silver(I) and adenine.

A simple and highly sensitive spectrophotometric method for the determination of biologically active thiols based on the fading of eosin-silver(I)-adenine ternary complex was established. In the determination of 6-mercaptopurine (MP), Beer's law was obeyed in the range 0.02-0.30 microg ml(-1), with an effective molar absorptivity at 562 nm and the relative standard deviation being 3.5 x 10(5) dm3 mol(-1) cm(-1) and 0.72% (n = 5). Analytical data for various biologically active thiols were determined with the proposed method. This method is about 5-10 times more sensitive than the conventional spectrophotometric methods. A compound having a disulfide bond (-S-S-), such as cystine, could also be determined by the conversion of disulfides to free thiols with the sulfite ion. The procedure was successfully applied to assays of various biologically active thiols in actual medicines.     

Experimental studies of electrical conduction mechanism of H2-reduced BaTiO3

ESR, resistivity and Seeback coefficient measurements have been performed on both ceramics and single crystals of reduced semiconducting BaTiO₃.From the results that the observed temperature dependence of the Seeback coefficient can be explained by the temperature dependence of carrier concentration estimated from the electric resistivity making use of the data of electron mobility, it is concluded that the electric conduction in reduced BaTiO₃ is due to the band conduction rather than to the hopping process. From the measurement of the temperature dependence of the ESR intensity of the F-center, the number of electrons trapped at the F-centers decreases exponentially with temperature, while the number of conduction electrons increases. This temperature dependence can not be simply explained as that of the unionized donors in semiconductor. Therefore, the ESR signal considered as that of the F-center may not be due to simple donors, even though some of the conduction electrons may be originated in them.     

High pressure effect on the electrical properties of NiS2

A semiconductor-metal transition in the electrical resistance of NiS₂, which has been suggested to be a Mott transition, is observed with decreasing temperature under pressure up to 44 kbar. The transition temperature increases with pressure with a slope of $\text{dT}\text{dP}\text{= 6 ± 1 K/kbar}$. The activation energy in a semiconducting region is found to decrease with increasing pressure and to vanish at about 46 kbar. The critical pressure and temperature are predicted to be 46 ± 2 kbar and 350 ± 20 K.     

On the orbital moment of Co in YCo5

The experimental result of the orbital and spin moments for Co in YCo₅ is analyzed by the use of the approximate d bands for YCo₅. The calculation of the anistropy constants K_u1 and K_u2 is worked out. Finally, the contributions to the anistropy constants due to 3d bands of Co_I, those of Co_II, those of Co_I and Co_II, and 3d and 4d bands of Co_I, Co_II and Y are discussed.