Thin-layer chromatographic demonstration of the herbicide zenkor

Established were the thin-layer chromatography conditions for the demonstration of the herbicide Zenkor as a pure substance and a preparation. Comparative experiments were carried out applying Thomson and Stanley's thin-layer chromatography conditions and the authors' personal ones. Most adequate proved to be the following conditions: sorbent-Kieselgel 60F 254 (Merck); solvent -- chloroform: 1,4-dioxan (9:1); developer -- ultraviolet light (authors' technique). Essential with this method is the preliminary (prior to apply the pure substances on the thin-layer chromatographic plaque) moving of the plaque in the indicated mobile phase (authors' technique). Under these thin-layer chromatography conditions work is made feasible and the method is fast and simple, achieving high sensitivity -- 0.5 mug Zenkor.     

General scheme of adsorption,electroreduction and catalytic hydrogenation of nitro-compounds on platinum—II. Mechanism of electroreduction and catalytic hydrogenation

The effect of basic kinetic parameters (potential, the nature and concentration of nitro-compounds solution pH, coverage of the surface with organic particles and hydrogen) on electroreduction and catalytic hydrogenation of nitro-compounds on platinum has been investigated. Direct comparison of kinetic and adsorption data obtained under the same conditions enabled the mechanism of these processes to be clarified.Kinetics of electroreduction of preliminarily chemisorbed semireduced nitro-compounds particles and kinetics of their hydrogenation by molecular and atomic hydrogen diffused through a palladium membrane have been investigated. Kinetics of interaction of hydrogen preliminaryly adsorbed on platinum with nitro-compounds has also been investigated.One and the same stage of interaction between a semireduced chemisorbed particle, formed in the preceding rapid stages of nitro-compound chemisorption, and adsorbed atomic hydrogen, formed in the preceding rapid electrochemical stage

or in the preceding rapid stage of molecular hydrogen adsorption

has been shown to represent the slow stage of electroreduction and catalytic liquid-phase hydrogenation of nitro-compounds on platinum.     

Magnetic nanostructures and nanodevices with a semiconductor or dielectric spacer

Magnetic properties of nanoscale magnetic-layer systems using FeNi, Co, FeMn, Al₂O₃, and SiC layers are studied experimentally. The dependence of magnetic behavior on the system geometry and parameters is addressed. Ferromagnet-semiconductor exchange coupling subject to the amplitude of an applied magnetic field is revealed. It is found that the magnetic behavior of the nanostructures varies in a nonlinear manner with applied magnetic field. Spin-tunneling magnetoresistance is observed in magnetic-layer junctions containing an Al₂O₃ spacer. In-plane-conduction magnetic-field sensors using an Al₂O₃ or a SiC spacer are fabricated and tested.Translated from Mikroelektronika, Vol. 34, No. 1, 2005, pp. 56–64.Original Russian Text Copyright © 2005 by Kasatkin, Muravjev, Plotnikova, Pudonin, Azhaeva, Sergeeva, Khodzhaev.