Catalytic oxidation of sulfide ions over nickel hydroxides

The catalytic sulfide ion oxidation by oxygen to elemental sulfur over β-Ni(OH)₂ and LiNiO₂ has been studied. As a result of experimental investigation performed, a reaction mechanism is suggested which involves heterogeneous and homogeneous processes. Dioxygen activation in the heterogeneous process proceeds via a redox Ni²⁺ ↔ Ni³⁺ transition and participation of OH⁻ groups. The active HO⁻₂ species thus formed carries on the reaction in homogeneous phase. Nickel hydroxides are promising catalysts for practical application.     

Determination of plutonium in soil and bottom sediments in the region of the scientific-research institute of atomic reactors

Scientific-Industrial Firm The Radium Institute. Scientific-Research Institute of Atomic Reactors, Dimitrovgrad. Translated from Atomnaya Énergiya, Vol. 75, No. 4, pp. 319-324, October, 1993.     

Manipulation of microparticles using Bessel beams from semiconductor lasers

Optical manipulation of microscopic objects (including living cells) using Bessel beams from semiconductor lasers has been demonstrated for the first time. In addition, it has been found in the experiments that a Bessel beam of sufficient power from a semiconductor laser makes it possible to manipulate simultaneously several microscopic objects captured into its central lobe and the first ring.     

Specific features of studying anisotropic media by methods of time-domain terahertz spectroscopy

Wide-band time-domain terahertz (THz) spectroscopy is a popular method of studying optical properties of various materials. This method is considered as applied to polarization-sensitive measurements of properties of anisotropic materials and media possessing significant dichroism and birefringence. It is important to understand that the development of the elemental base for the terahertz range, in particular, for THz polarizers, falls behind the achievements of polarization optics for the visible range. In studying anisotropic materials, this may lead to simultaneous detection of orthogonal components of the THz field and to formation of artifacts in the spectral range in calculations of properties of examined samples. A unique specific feature of time-domain terahertz spectroscopy, namely, a possibility of capturing the time-dependent shape of the THz pulse, allows separation of the orthogonal components of the field in the time domain. Thus, it is possible to detect the signal from radiation with the orthogonal polarization and eliminate it by means of appropriate adjustment of polarization elements of the spectroscopy system. This method is demonstrated by an example of studying the terahertz properties along the optical axis z of an anisotropic ferroelectric crystal of lead germanate in which significant birefringence and dichroism arise as the crystal is heated to the phase transition temperature.     

Electrochemical studies of the kinetics and mechanism of brass dezincification

By a combination of electrochemcial and radiotracer measurement a study was made of the dezincification of β-brass in an acid chloride solution under conditions of continuous introduction of Cu⁺ ions by means of anodic dissolution of an auxilary copper electrode. Through a comparison of the partial rate of zinc dissolution from brass with the results of the measurement of the corrosion potential of brass and the potential of the indicator copper electrode, the relationship was established between the electrochemical characteristics of the alloy and the process of its dezincification caused by the copper redeposition from the solution. The conclusion about the copper redeposition was confirmed by electron-microscopic studies and an electron-microprobe analysis of the brass surface. It was shown that in principle an electrochemical technique can be used to evaluate the susceptibility of brass to dezincification.