Natural radioactivity in springs of Sverdlovsk region,Middle Urals,Russia

Journal of Radioanalytical and Nuclear Chemistry - Activity concentrations of natural radionuclides were determined in water from 31 springs of Sverdlovsk region, Middle Urals, Russia. Activity...     

Convective instability of a zinc sulfate solution in a cell with horizontal plane-parallel electrodes

The Rayleigh-Bénard convective instability in a cell with horizontal zinc electrodes is considered. The space between the electrodes is filled with a ZnSO₄ solution. The linear plot of the difference between the zinc deposition currents (I) in the cases where the anode is the upper or lower electrode vs. the square root of the zinc deposition current in the absence of convection is found experimentally. It is shown that the critical Rayleigh number can be determined by an extrapolation of this plot.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 247–249.Original Russian Text Copyright © 2005 by Tomashova, Teplitskaya, Grigin, Davydov.     

Limiting Current of Copper Electrodeposition from a Copper Sulfate Solution under Conditions of Natural Convection: The Space Charge Effect

Copper electrodeposition from a copper sulfate solution under conditions of natural convection is analyzed theoretically and examined experimentally. The space charge, which forms in the near-cathode layer, is shown to affect the limiting current density and to change its concentration dependence.     

Determination of Critical Rayleigh Number for Binary Solutions in a Nonlinear Theory of Convective Stability

The Rayleigh–Benard convective instability in a cell with horizontal copper electrodes is considered. The space between the electrodes is filled with a CuSO₄ solution. The dependence of the variation in the limiting current of copper deposition, I, which is caused by the formation of convective dissipative structures in the system, on the solution concentration is determined experimentally. The results agree satisfactorily with a nonlinear theory of convective stability that accounts for the electrical forces generated by the formation of a space charge near the electrode, along with the buoyancy forces. This enables one to determine the critical Rayleigh number for the system by extrapolating the linear dependence of I on . The critical Rayleigh number thus obtained agrees satisfactorily with the theoretical value calculated within the linear theory of stability.