Combined standardless electrochemical method for determination of lead(II), copper(II), and cadmium(II) in aqueous solutions

A combined standardless method (no calibration of the device against standard solutions or use of the method of additives is required) for determination of lead, copper, and cadmium in aqueous solutions is suggested. The method operates on principles of inversion voltammetry and potentiostatic coulometry. It is convenient for automated analysis of technological solutions and wastewater from electroplating and hydrometallurgical shops.     

Sorption of Uranium from Sulfuric Acid Leaching Solutions by Strongly Basic Anion Exchangers

The equilibrium and kinetic characteristics of uranium sorption from simulated sulfuric acid leaching solutions by AMP, Lewatit K 6367, Purolite A 500, Purolite A 600, and AM-p gel-like and porous strongly basic anion exchangers were studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 736–740.Original Russian Text Copyright © 2005 by Kolomiets, Troshkina, Sheremet’ev, Konopleva.     

Natural convection in a closed parallelepiped with a local energy source

An experimental and numerical analysis was performed to investigate the laminar regimes of conjugate thermogravitational convection in a closed parallelepiped with heat-conducting walls of finite thickness in the presence of a local energy source with convective heat exchange with the environment. The numerical studies were performed using the Fluent software. The experimental data and numerical results agree well each other.     

Enhancement of electromagnetically induced transparency in room temperature alkali metal vapor

Electromagnetically induced transparency (EIT) has led to several quantum optics effects such as lasing without inversion or squeezed light generation. More recently quantum memories based on EIT have been experimentally implemented in different systems such as alkali metal atoms. In this system the excited state of the optical transition splits into several sublevels due to the hyperfine interaction. However, most of the theoretical models used to describe the experimental results are based on a Λ-system with only one excited state. In this article, we present a theoretical model for the Λ-type interaction of two light, fields and an atomic system with multiple excited state. In particular we show that if the control and probe fields are orthogonally circularly polarized the EIT effect in an alkali-metal vapor can almost disappears. We also identify the reasons of this reduction and propose a method to recover the transparency via velocity selective optical pumping.     

β,β-Dinitrostyrenes in reactions with cyclohexane-1,3-diones

The Michael-type addition of dimedone and dihydroresorcinol to β,β-dinitrostyrenes occurs easily without a catalyst. The adducts cyclize into 3-aryl-2-nitro-2,3,4,5,6-hexahydrobenzofuran-4-ones under the action of triethylamine.     

Diophantine laws for nets of the highest symmetries

The theoretical-numerical properties of the square and the hexagonal nets are presented as well as their characteristic triads of integers—the Denis numbers—applicable to the practical X-ray diffraction analysis of single crystals.