A study of the stability of the solutions of certain nonlinear systems

We use the method of Lyapunov functions to study the stability of the solutions of certain nonlinear systems close to Bazhevskii systems, and also stability in the cone x≥0, x∈Rⁿ, of a system of differential equations with a polynomial right-hand side. We consider an application to the method of Lyapunov vector functions in the case when the system of equations is essentially nonlinear. Translated fromDinamicheskie Sistemy, No. 13, 1994, pp. 6–12.     

Clean reconstructed InAs(1 1 1) A and B surfaces using chemical treatments and annealing

Well-ordered clean InAs(1 1 1) A and B surfaces have been prepared using HCl-isopropanol solutions and characterized using low-energy electron diffraction and photoemission spectroscopy. The as-treated surfaces are covered by a layer containing arsenic and small amounts of InCl_x. Annealing induces desorption of the overlayer and reveals (2 × 2) and (1 × 1) structures on the A and B surfaces, respectively. For both surfaces, the surface components of the In 4d and As 3d reveal a charge transfer from the electropositive surface indium to the electronegative surface arsenic. The major advantage of this preparation method over conventional thermal cleaning is a significant reduction in the annealing temperature (≈250 °C) thereby avoiding anion evaporation.     

Electrochemical synthesis of perfluoropolyethers by the Kolbe method

Electrochemical dimerization of hexafluoropropylene oxide dimer and trimer acids on SU-2000 glassy carbon, bulk platinum, and SU-2000 electrodes modified with platinum-group metals in acetonitrile in the presence of water was studied at various concentrations of the starting substance and different degrees of neutralization of the starting acid. Also, the possibility was examined of obtaining some perfluoropolyethers in a single process by cross-condensation of several starting perfluorocarboxylic acids, followed by separation of the products by physicochemical methods.     

Properties of methylammonium lead iodide perovskite single crystals

The technique for growing CH₃NH₃PbI₃ single crystals from saturated solutions in concentrated hydroiodic acid is improved by introducing a reducing agent (hypophosphorous acid). The structure of perovskite is confirmed by single crystal XRD. By energy dispersive spectroscopy and X-ray photoelectron spectroscopy it is established that the stoichiometry of the grown crystals corresponds to the CH₃NH₃PbI₃ compound. Changes in the photoluminescence intensity during in-air measurements show that the crystals synthesized using the reducing agent are more stable in the external environment with laser exposure than without it.     

Quick ellipsometric technique for determining the thicknesses and optical constant profiles of Fe/SiO2/Si(100) nanostructures during growth

An algorithm is developed to perform rapid control of the thickness and optical constants of a film structure during growth. This algorithm is tested on Fe/SiO₂/Si(100) structures grown in an Angara molecular-beam epitaxy setup. The film thicknesses determined during their growth are compared with X-ray spectral fluorescence analysis and transmission electron microscopy data.     

Chemically prepared well-ordered InP(0 0 1) surfaces

In the present work HCl-isopropanol treated and vacuum annealed InP(0 0 1) surfaces were studied by means of low-energy electron diffraction (LEED), soft X-ray photoemission (SXPS), and reflectance anisotropy (RAS) spectroscopies. The treatment removes the natural oxide and leaves on the surface a physisorbed overlayer containing InCl_x and phosphorus. Annealing at 230 °C induces desorption of InCl_x overlayer and reveals a P-rich (2 × 1) surface. Subsequent annealing at higher temperature induces In-rich (2 × 4) surface. The structural properties of chemically prepared InP(0 0 1) surfaces were found to be similar to those obtained by decapping of As/P-capped epitaxial layers.     

Temperature characteristics of exciton-phonon luminescence of zinc oxide

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 5, pp. 750–753, May, 1989.     

Influence of the Composition of Chloride-containing Solutions on the Corrosion of 12Cr18Ni10Ti Steel

The corrosion activity of chloride-containing solutions formed in production of ternary nitrogen-phosphorus-potassium fertilizers was studied. The inhibiting effect of hydroxide ions on the corrosion of 12Cr18Ni10Ti steel during the evaporation of solutions of nitrogen-phosphorus-potassium fertilizers was evaluated.