Electrodeposition of composite Fe–TiO<Subscript>2</Subscript> coatings from methanesulfonate electrolyte

The process of electrodeposition of an iron–titania composite electrochemical coating from methanesulfonate electrolyte is studied. TiO₂ Degussa P 25 nanopowder (a mixture of crystalline modifications of rutile and anatase, with the latter prevailing) is used for preparation of suspension electrolyte. The dispersed phase content in the composition coating increases at a decrease in current density and increase in TiO₂ in the suspension. It is shown that kinetics of codeposition is adequately described by the improved Guglielmi model. It is shown that inclusion of TiO₂ particles into an iron matrix results in an increase in microhardness of the coating due to dispersion strengthening. Fe–TiO₂ (anatase+rutile) coatings manifest photocatalytic activity with respect to the reaction of destruction of the methyl orange dye in aqueous solutions under exposure to UV radiation, and this activity is higher than in the case of similar coatings containing TiO₂–rutile particles.     

Measuring pressure of pulsed plasma flows by quadrature interferometry techniques

We have developed a new method for measuring the gaskinetic pressure of corpuscular flows in pulsed plasma that employs a probe in the form of an acoustic rod incorporated in the optical scheme of a laser interferometer. This method has been used to study the temporal dynamics of the pressure of corpuscular flows emerging from a micropinch discharge of the low-inductance vacuum spark type. Due to a large dynamic range (～10⁵), the proposed method can be implemented in a large variety of plasma setups with a broad range of parameters.     

Aspects of strategy of HTGR introduction into hydrogen energy

Solution of the current problem of essential substitution of atomic energy for oil and gas consumption requires development and introduction of the designs for atomic energy utilization not only in the electrical energy industry but also in other fields of oil and gas consumption, such as heat generation for industrial and district purposes, metallurgy, chemistry, and transport. Introduction of atomic energy to these fields Si the most important problem to be solved [1]. Investigations on the high-temperature helium-cooled reactors showed that these reactors can possibly be used for this purpose. When the temperature potential of 900–1000°C is reached for these reactors [2] the atomic energy will be efficiently used in the main power-intensive technological processes currently consuming a large fraction of the oil and natural gas [3].     

Electrodeposition of chromium coatings from sulfate–carbamide electrolytes based on Cr(III) compounds

We propose an electrolyte based on chromium sulfate (1 mole/liter Cr(III)) and containing both formic acid and carbamide (urea). This electrolyte enables one to get Cr coatings with a thickness of several micrometers. It is shown that the current yield and deposition rate increase as the current density and pH value increase and temperature decreases. We select the optimal conditions of electrolysis under which bright high-quality chromium deposits are obtained. In this case, the deposition rate of the metal varies from 0.5 to 1.5 μm/min. It is shown that the optimal concentration of both formic acid and carbamide is equal to 0.5 mole/liter. The necessity of using certain surface-active substances to prevent the formation of pitting on the surface of the deposit is demonstrated. Moreover, it is discovered that the microhardness of Cr deposits attains its highest values (950–980kg/mm²) for currents with densities of 30–35 A⋅dm⁻² and decreases as the pH value and temperature increase. Electrolysis is realized by using titanium–manganese-dioxide anodes and, hence, it is not necessary to separate the cathodic and anodic spaces.     

Surface and grain boundary wetting of Fe based solids by molten Pb and Pb-Bi eutectic

Surface and grain boundary wetting and penetration of pure Fe and a martensitic steel by Pb and Pb-Bi eutectic alloys were studied by the sessile drop and dispensed drop techniques at different temperatures (400–900^°C) and times (up to 30 h). By using two different atmospheres—high vacuum and a He-H₂ gas—and different heat treatments, wetting was studied for both oxidized and deoxidized solid substrates.     

Cavity solitons in a driven VCSEL above threshold

We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.     

Mathematical modelling of the contribution of mechanical inhomogeneity in the myocardium to contractile function

Earlier we developed a mathematical model of the cardiac muscle that allowed for inactivation through the effects of cooperativity of contractile proteins. In the present work we used the model to analyze the mechanical function of an inhomogeneous myocardium. To simulate the latter we chose, as the simplest sytstem, a duplex in which muscles with different mechanical properties were connected in series and in parallel. Numerical experiments showed that the basic effect due to the inhomogeneity consists in the non-additivity of the mechanical characteristics of the muscle, e.g., of the relationship between end-systolic length and end-systolic force (Les - Pes). As a rule, non-additivity consists in a negative inotropic effect. The analysis showed that the cause of non-additivity is redistribution of loads between muscles (in a parallel duplex), redistribution of lengths (in a serial duplex), changes in the rate of contraction of each muscle compared to contraction that when working separately, shifts in time to Les. Also, the model predicts that additional inactivation of contractile proteins in a muscle within a duplex against isolation is the substantial mechanism of enhanced non-additivity. Among the factors of inhomogeneity studied the basic determinants are difference in amplitudes between isometric tensions developed by each muscle in isolation and the asynchronism in the development of these tensions.     

Stabilization of the properties of high-molecular-weight cellulose acetate

Treatment of high-molecular-weight cellulose acetate (HCA) with acetone-water mixture (55:45 wt. %) increased the mol. wt. of the polymer and gave solutions a more homogeneous structure. It was shown that films made of HCA had a more ordered structure after this treatment. It is recommended that batches of HCA with a high enough mol. wt. be treated with acetone-water mixture to obtain cellulose hydrate fibre with stable properties.Scientific-Research Institute of Chemistry, Saratov State University. All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated from Khimicheskie Volokna, No. 1, pp. 34–35, January–February, 1994.