Effect of microwave irradiation on the photoluminescence of bound excitons in CdTe:Cl single crystals

The effect of microwave radiation on the transformation of impurity-based structural complexes in Cd_Te:Cl single crystals is studied using low-temperature photoluminescence measurements. It is shown that microwave radiation activates Cl_Te centers, resulting in an increase in the intensity of photoluminescence line of excitons bound at the corresponding Cl_Te donor centers. A nonmonotonic dependence of the integrated photoluminescence intensity on the duration of microwave irradiation is observed. At the initial stage of microwave irradiation (t = 30 s), an increase in the integrated excitonic photoluminescence intensity is observed; as the duration of microwave irradiation is increased, the photoluminescence intensity decreases. The experimentally observed variations in the photoluminescence intensity are athermal in nature. The hypothetical mechanism of transformation of impurity-based structural complexes is described.     

Fractionation of resins and asphaltenes and investigation of their composition and structure using heavy oil from the Usa field as an example

Asphaltenes and resins of crude oil from the Usa oil field have been subjected to fractionation. The asphaltenes have been separated into fractions by fractional precipitation with chloroform/hexane solvent blends in the ratios of 30/70, 30/75, and 30/120. The resins have been fractionated by liquid adsorption chromatography on silica gel with hexane/benzene and hexane/ethanol mixed solvents taken in the ratios of 3/1, 1/1, and 10/1, 3/1, respectively. The obtained fractions have been analyzed by ¹H and ¹³C nuclear magnetic resonance spectroscopy and infrared spectroscopy, their molecular masses have been measured, and the elemental composition has been investigated. On the basis of structuralgroup analysis data, the structures of the resin and asphaltene molecules have been hypothesized.     

Contamination of the transformer oil of power transformers and shunting reactors by metal-containing colloidal particles

The results of a measurement of the contamination of the oil in 66 transformers by metal-containing colloidal particles, formed as a result of the interaction of the oil with the structural materials (the copper of the windings, the iron of the tank and core etc.), and also the results of measurements of the optical turbidity of the oil in 136 transformers when they were examined at the Power Engineering Research and Development Center Company are presented. Methods of determining the concentration of copper and iron in transformer oil are considered. The limiting values of the optical turbidity factors, the copper and iron content are determined. These can serve as a basis for taking decisions on whether to replace the silica gel of the filters for continuously purifying the oil of power transformers and the shunting reactors in addition to the standardized oil contamination factors, namely, the dielectric loss tangent and the acidity number of the oil.     

Determining steady-state temperature excess and time constants using data of thermal tests of transformers

A method for calculating the steady-state temperature excess and thermal time constants of elements of power transformers using the so-called three-point formula proposed in [4] is generalized with allowance for the thermal nonuniformity of transformers and developed with allowances made for statistical data. The method uses data of thermal testing in the form of a time dependence of the temperature excess at a controlled point (heating curve). The possibility of applying a method for shortening thermal testing is shown.     

Mathematical model of heating a prism with boundary conditions of the 3rd kind

This paper describes the procedure of computational determination of the temperature field of a prismatic workpiece heated in a continuous furnace with account for the temperature dependence of the thermal diffusivity. For a numerical solution of the two-dimensional heat conduction equation with boundary conditions of the 3rd kind, an implicit scheme has been used. The calculated time dependences of the temperature for three characteristic points of the cross-section of the prismatic steel workpiece have been compared to the experimental data. The heat transfer coefficients at which the experimental data and the calculated values have a minimum discrepancy have been determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 6, pp. 3–8, November–December, 2007.     

Study of compatibility of polymethylsiloxane liquid PMS-10 with structural materials

The influence of structural materials on the principal electrophysical characteristics (relative permittivity, loss tangent, volume electric resistivity, and electric strength) of polymethylsiloxane liquid PMS-10 is considered in the paper.     

Effects of genetic polymorphism of phosphoglucomutase identifiable in human milk (PGM4 locus) on the somatotype of the newborn and reproductive function of women

The polyacrylamide gel isoelectrofocusing technique was used to examine structural variations of the human milk-expressed enzyme PGM4-locus phosphoglucomutase. Six phenotypes controlled by four alleles: PGM4*1, PGM4*2, PGM4*3, PGM4*4 with frequencies of 0.261, 0.664, 0.047, 0.028, respectively, were identified in 180 milk samples taken from Moscow Russian women in labour. The empirical distribution of the PGM4 phenotypes is in a moderate agreement with the expected one with chi 2 = 9.622; 6 d.f. (p > 0.05). Its phenotypic belonging to PGM4 1-2 and PGM4 2-2 was examined for its influence on female reproductive function and neonatal somatic type. The PGM4 1-2 phenotype was positively associated with miscarriages whereas PGM4 2-2 negatively correlated with this abnormality. If the mother had PGM4 2-2, there might be increased body dimensions (body length and mass, head and chest circumferences) in male neonates. On the contrary, PGM4 1-2 was negatively correlated with body length and mass in the newborns of both sexes. For female neonates, there was a highly significant association only with the presence of PGM4 2-2 in their mothers, namely: its presence was positively correlated with all body dimensions.