Functional reserves of humans in North condition and its providing of fat-soluble vitamins

It was been examined 810 healthy peoples inhabited in Russian European North. It was been shown that more than 35% of examined person from different group have lowered serum level of retinol and alpha-tocopherol. Described that alpha-tocopherol deficits occur more often and proposed that it cased as a result of free radical oxidation typical for North inhabitances.     

Effect of Chemical Polishing on the Photoconductivity of Bi12SiO20

After chemical polishing, the spectral response of bismuth silicate crystals shows a minimum at 0.41–0.43 m, where photosensitivity is comparable to that in the red spectral region (0.6–0.63 m).     

Effect of thermal treatment on states of molybdenum in Mo/H–ZSM-5 catalyst for methane dehydroaromatization: ESR and UV–VIS study

Valence and coordination states of molybdenum ions formed upon thermal treatment of Mo/H–ZSM-5 catalyst for methane dehydroaromatization in Ar and Ar/CH₄ media at 573–973 K have been studied by ESR and UV–VIS spectroscopy. For comparison, the characteristic ESR spectra of thermolyzed bulk ammonium heptamolybdate have been studied and analyzed in detail. The nature of earlier observed Mo⁵⁺ ions has been verified, and new paramagnetic states of molybdenum in Mo/H–ZSM-5 catalysts have been detected: Mo³⁺ ions, and Mo⁵⁺ ions in tetrahedral coordination with delocalization of unpaired electron to Al and H or Al and N atoms.     

Pyrolitic Methods of the Thermal Processing of Solid Municipal Waste

High Temperature - The results of studies on the application of pyrolytic methods for the processing of solid municipal waste into liquid and gaseous fuels are presented. The features and types of...     

Two-stage pyrolytic conversion of different types of biomass into synthesis gas

Possibilities of using the method of two-stage pyrolytic processing of the main types of biomass for the production of synthesis gas are considered. A comparison of the biomass characteristics (volatile content, ash content, elemental composition, and heating value) and the characteristics of gas mixtures obtained from it (volume, composition, and heating value) is performed. From the results obtained, it follows that the considered method of pyrolytic processing allows obtainment of 1.25 to 1.39 m³ of synthesis gas (per kg of combustible mass of the raw material) with heating value at 10–12 MJ/m³, and a high degree of energy conversion as compared with other methods for biomass gasification.     

Evaluation of Impurity Concentration in Semiconductors from the Relaxation of Thermally Stimulated Currents

The rate equations of thermally stimulated currents due to isothermal detrapping are analyzed. The results demonstrate that, at small trap population, isothermal detrapping follows an exponential law, independent of the trapping rate: fast, slow, or intermediate (the trapping time is comparable to the recombination time). Expressions are derived for determining the density of charged traps in the course of detrapping and assessing the trap density from known trap parameters and thermally stimulated current spectra.     

Light-induced processes in a-Si:H films at elevated temperatures

At temperatures T>120 °C the kinetics of the dark conductivity (σ _d) of undoped and borondoped a-Si:H films during and after the cessation of illumination is observed to be nonmonotonic, with fast and slow processes of variation of σ _d of opposite sign. A fast or slow σ _d relaxation process described by a stretched exponential function can be isolated by varying the duration and intensity of illumination or the film temperature. The nonmonotonic relaxation of σ _d is described by a sum of two stretched exponentials, whose parameters τ and β depend on the film characteristics and on the temperature, exposure time, and intensity of illumination. The nature of the nonmonotonic relaxation is discussed. Fiz. Tekh. Poluprovodn. 31, 1455–1459 (December 1997)     

Thermally Stimulated Currents in Semiconductors: Analysis of Rate Equations for a Single-Level Model and Thermally Stimulated Currents in Si<P,Au>

Thermally stimulated currents (TSCs) in semiconductors are analyzed theoretically. The rate equations describing TSCs are solved numerically for various heating profiles, which makes it possible to evaluate the ionization energy, concentration, and capture cross section of traps. The slow and fast retrapping approximations are examined for an arbitrary heating profile. A new approach to TSC data processing is proposed: cleaning of a peak from the lower temperature peak by storing the preilluminated material in the dark at the relaxation temperature of the lower temperature peak. It is shown that heating (constant-rate or exponential) followed by isothermal holding makes it possible to determine the ionization energy of traps without knowing the retrapping mechanism. This approach is adapted for the case when the retrapping time is comparable to the carrier lifetime. Partially compensated silicon with impurity photoconductivity is prepared by doping with gold and phosphorus. It is shown that, using resonance photoexcitation, one can identify the nature (electron or hole) of traps and evaluate their ionization energy. The depths and capture cross sections of three trapping centers in Si were evaluated.