Enzymatic Responses to Low-Intensity Radiation of Tritium

The present study considers a possible role of enzymatic reactions in the adaptive response of cells to the beta-emitting radionuclide tritium under conditions of low-dose exposures. Effects of tritiated water (HTO) on the reactions of bacterial luciferase and NAD(P)H:FMN-oxidoreductase, as well as a coupled system of these two reactions, were studied at radioactivity concentrations ≤ 200 MBq/L. Additionally, one of the simplest enzymatic reactions, photobiochemical proton transfer in Coelenteramide-containing Fluorescent Protein (CLM-FP), was also investigated. We found that HTO increased the activity of NAD(P)H:FMN-oxidoreductase at the initial stage of its reaction (by up to 230%); however, a rise of luciferase activity was moderate (<20%). The CLM-FP samples did not show any increase in the rate of the photobiochemical proton transfer under the exposure to HTO. The responses of the enzyme systems were compared to the ‘hormetic’ response of luminous marine bacterial cells studied earlier. We conclude that (1) the oxidoreductase reaction contributes significantly to the activation of the coupled enzyme system and bacterial cells by tritium, and (2) an increase in the organization level of biological systems promotes the hormesis phenomenon.     

Physicomechanical Properties and Phase Composition of Unfired Periclase-Carbon Refractories Based on Modified Phenol-Formaldehyde Resin

Refractories and Industrial Ceramics - Possibilities for improving the physicomechanical properties of periclase-carbon materials by modifying phenol-formaldehyde resin (PFR) with organo-inorganic...     

Calculation of the characteristics of countercurrent axisymmetric jets

On the basis of analysis and generalization of experimental data, a method is proposed for calculating the parameters of the interaction of two coaxial jets flowing in opposite directions from circular nozzles of different diameters.Notation d, D diameter of the nozzles for the small- and large-diameter jets - density - x, y coordinates - u, U averaged longitudinal component of velocity of the small- and large-diameter jets - L_ax distance between nozzles - q relative impulse - G mass rate of the medium - 2r width of the jet - _i, L_i lengths of the flow zones of the small- and large-diameter jets, where i=1, 2 - range of the jet - 2B distance between corresponding points of lines of maximum velocity of the large-diameter jet Indices 0 initial state - m maximum value - ax value on the axis - d large-diameter jet - y_0.5 distance from the axis to the point at which the velocity is equal to half the velocity on the axis Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 5, pp. 725–729, May, 1989.     

Management of composition cathodic products in the electrolysis of molybdenum‐, tungsten‐ and carbon‐ bearing halogenide‐oxide and oxide melts

It is shown that the cathode products of electrolysis of melts based on a eutectic mixture of sodium chloride and lithium fluoride as well as melts based on sodium tungstate in which dissolved oxides of molybdenum (VI) or tungsten (VI), molybdate, tungstate and lithium or sodium carbonates are molybdenum, tungsten, their bronzes and carbides, carbon. It is established that the phase composition of electrolysis products is determined by the concentration of carbonate in the melt. Particular conditions of plating coating of molybdenum and tungsten carbides on carbon, nickel and copper materials are determined. Molybdenum carbide coatings of electrolyte Na₂WO₄–Li₂MoO₄–Li₂CO₃ are deposited at equality (within 2.5 mol%) of concentrations molybdate and lithium carbonate. However, their concentrations should not exceed 10 mol%. At lower concentrations of molybdate in the precipitate are detected carbon, molybdenum, molybdenum carbide, and at high concentrations – molybdenum oxides. At lower concentrations of carbonate in the sediment dominates molybdenum and at large concentrations mainly free carbon is released. More affordable industrial reagent‐source of molybdenum is its oxide.     

Diffusion saturation of nickel alloys with aluminum and chromium from the gas phase by the circulation method

Protective coatings on parts made of high-temperature nickel alloys increase substantially their service life and resistance to oxidation and corrosion in a high-temperature gas medium. A promising direction in this respect is the use of a gas circulation method for depositing protective coatings that envisages separated positioning of the saturated alloy and the saturating powder containing chromium, aluminum, cobalt, and other elements. Transfer of these elements to the surface of the saturated alloy occurs by means of forced circulation of the gas phase in the closed volume of the installation at a specified temperature. The present work is devoted to the problem of diffusion saturation of the surface of nickel alloys of the ZhS type with Cr and Al by the gas circulation method. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 21–25, October, 1998.