Electrodeposition of lead–tin alloy from methanesulphonate bath containing organic surfactants

The article discusses the process of electrodeposition of lead-tin alloy (tin content in the deposit up to 10–12 wt %) from methanesulfonate electrolytes. A composition was proposed of organic additives to the electrolyte providing attainment of high quality microcrystalline coatings with the alloy of predetermined composition at relatively low content of Sn²⁺ in the solution. It has been shown that the tin content in the deposit increases at an increase in current density and decrease in the electrolyte temperature. For production of anti-frictional Pb-Sn alloys with the tin content of about 10% the electrolysis should be performed at a current density of about 4 A/dm² and the temperature not exceeding 25°C. The effect of a decrease in the discharge rate of the Sn²⁺ ions into the alloy at deposition from electrolyte without organic additives was discovered, that is stipulated by deceleration of crystallization stage of tin on foreign substrate. When the alloy is deposited from electrolyte containing a composition of organic additives, the effect of super-polarization of discharge of Sn²⁺ ions is reduced.     

Contractile Behavior of Right Atrial Myocardium of Healthy Rats and Rats with the Experimental Model of Pulmonary Hypertension

There is a lack of data about the contractile behavior of the right atrial myocardium in chronic pulmonary heart disease. We thoroughly characterized the contractility and Ca transient of isolated right atrial strips of healthy rats (CONT) and rats with the experimental model of monocrotaline-induced pulmonary hypertension (MCT) in steady state at different preloads (isometric force-length), during slow force response to stretch (SFR), and during post-rest potentiation after a period of absence of electrical stimulation (PRP). The preload-dependent changes in the isometric twitch and Ca transient did not differ between CONT and MCT rats while the kinetics of the twitch and Ca transient were noticeably slowed down in the MCT rats. The magnitude of SFR was significantly elevated in the MCT right atrial strips and this was accompanied by the significantly higher elevation of the Ca transient relative amplitude at the end of SFR. The slow changes in the contractility and Ca transient in the PRP protocol did not differ between CONT and MCT. In conclusion, the alterations in the contractility and Ca transient of the right atrial myocardium of monocrotaline-treated rats with pulmonary hypertension mostly concern the elevation in SFR. We hypothesize that this positive inotropic effect in the atrial myocardium may (partly) compensate the systolic deficiency of the right ventricular failing myocardium.     

Kinetics and mechanism of chromium electrodeposition from methanesulfonate solutions of Cr(III) salts

Kinetics and mechanism of the chromium electrodeposition process in methanesulfonate and sulfate solutions of Cr(III) ions have been investigated. The electroreduction of Cr(III) complex ions is shown to proceed stepwise with the formation of relatively stable intermediates—Cr(II) compounds. Chromium is established to be deposited via the discharge of Cr(II) hydroxocomplexes in these electrochemical systems. Some differences in electrodeposition behavior of methanesulfonate and sulfate trivalent chromium electrolytes are associated with the differences in their buffering capacity.     

Heat treatment of high-molecular-weight cellulose acetate fibres

The conditions for heat treatment of high-molecular-weight cellulose acetate fibres which ensure formation of an ordered fibre structure with elevated strength properties were established. An ordered structure can be obtained in heat treatment if the acetate fibre is wet spun with positive spinneret drawing.Scientific-Research Institute of Chemistry, Saratov State University. All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated from Khimicheskie Volokna, No. 6, pp. 29–31, November–December, 1992.     

Applying a theory of generalized variables to electrochemical kinetics: Interpreting the results of studying chromium deposition from Cr(III) baths

By using the theory of generalized variables (the similarity theory and dimensional analysis), universal system of dimensionless complexes (the similarity criteria) is derived, which allows describing the kinetics of multistage reaction (metal electrodeposition at rotating disc electrode). The proposed mathematical apparatus can be flexibly adapted to describing the kinetics of virtually any complicated electrochemical system. The dimensionless complexes derived are used in interpreting the results of our studies on the chromium electrodeposition from Cr(III) oxalate and formate salt solutions at a rotating disc electrode. Possible mechanism of the electrodeposition from the oxalate and formate electrolytes is offered. Original Russian Text ? V.S. Protsenko, T.E. Butyrina, F.I. Danilov, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 4, pp. 429–438.