Magnetic fields at 181Ta nuclei in Laves phases of RFe2 (R=Nd, Pr, Sm, Gd, Dy, Yb, Lu)

By studying the perturbed angular correlations of γ-rays emitted during the decay of ¹⁸¹Hf impurities in the Laves phases of PrFe₂, DyFe₂, and YbFe₂, we have investigated the magnetic hyperfine interaction between these compounds and its daughter nucleus ¹⁸¹Ta, and have determined the temperature dependence of the magnetic hyperfine fields. At room temperature we obtained the following values of these magnetic hyperfine fields B _hf:B _hf(PrFe₂)=7.6(1) T, B _hf(DyFe₂)=15.5(5) T, and B _hf(YbFe₂)=18.8(3) T. When taken together with data obtained previously, the results of our experiments show that for Ta nuclei in the RFe₂ Laves phases the values of B _hf depend strongly on whether R is a light or a heavy rare-earth element, which allows us to conclude that in these phases the value of the magnetic moment induced at the impurity Ta nuclei depends on the interatomic distance. Zh. éksp. Teor. Fiz. 111, 1085–1091 (March 1997)     

Hydrothermal synthesis and crystal structure of lithium scandium orthophosphate Li2Sc[H(PO4)2]. The Li2MIII[H(PO4)2] family (MIII = Fe, Sc, In)

Conditions of the hydrothermal synthesis of scandium hydrogen orthophosphate Li₂Sc[H(PO₄)₂] (I) have been studied and the range of its monomineral crystallization have been determined. The existence of bound hydrogen in the structure has been confirmed by IR spectroscopy. The crystals of I are monoclinic: a = 4.857(1) ?, b = 8.198(2) ?, c = 7.664(2) ?, β = 104.097(5)°, space group P2₁/n, Z = 2. The structure was solved by direct methods and refined by full-matrix least-squares calculation in the anisotropic approximation for all non-hydrogen atoms, R _obs = 0.0215, R _wall = 0.0335 (705 reflections with I > 3σ(I)). The basis of the structure is a mixed anionic para-framework {Sc[H(PO₄)₂]}_3∞²⁻, composed of vertex-sharing ScO₆ octahedra and PO₄ tetrahedra. The structural unit of the para-framework is the microblock [ScP₆O₂₄] with symmetry $ \bar 1 $ \bar 1 . The microblocks are condensed in columns running in the [100] direction to form through channels filled with Li⁺ cations (CN = 5). A model with splitting of the hydrogen atom position implying the formation of a strong asymmetric nonlinear H-bond has been suggested and considered. The compound is stable to 400°C. The results of studying compound I are presented together with the data on the Fe- and In-containing Li₂M^III[H(PO₄)₂] analogues.     

Hybrid macromolecular antioxidants based on hydrophilic polymers and sterically hindered phenols

A novel class of biologically active substances was created. These are hybrid macromolecular antioxidants (HMAO) based on hydrophilic polymers with chemically grafted sterically hindered phenols with different structural parameters. The antiradical activities of HMAO were assessed in reactions with 2,2-diphenyl-1-picrylhydrazyl and the corresponding sodium sulfonate in various solvents. The mechanism that explains the substantially enhanced activities of HMAO in water was proposed. The state of HMAO in solutions was studied by viscosimetry and photon correlation spectroscopy. HMAO were assayed in biological models. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 751–760, April, 2007.     

Space anisotropy of bottom reverberation in the coastal zone

A method for calculating the bottom reverberation in a coastal zone with allowance for the three-dimensional bottom topography, which affects the spatial anisotropy of the incoming reverberation signal, is proposed. The method is based on the ray approach in combination with the use of the ray invariant. Examples of calculating the monostatic bottom reverberation level for one of the coastal regions with a complex bottom topography including the coastal line and an underwater elevation are presented.     

Correlation between the chromatographic retention and physicochemical properties of azoles

The chromatographic behavior of previously unknown nitrogen-containing heterocyclic compounds was studied by reversed-phase high-performance liquid chromatography. The main relationships in the retention of the compounds with variation of the acetonitrile content in the mobile phase were examined. One-and multiparameter correlations between the logarithm of the retention factor and quantities characterizing physicochemical properties of the compounds were constructed.     

An approach to studying nonsteady-state vibrations of a finite length cylinder

A method is given for analyzing the nonsteady-state vibrations of a finite length cylinder based on using Laplace transforms and approaches developed previously for determining the vibration natural frequencies and forms. A numerical method is demonstrated for determining residues with reference to expressions for displacements and stresses. Quantitative estimates are given for stresses in a cylinder for a specific principle of the change in load with time and features of the time-dependent behavior of displacements in relation to the magnitude of the area of loading at the end are studied.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 18, pp. 129–133, 1987.     

The solid-phase catalytic oxydation of 2-hydroxy-3,5-di-tert-butylbenzyl alcohol

The solid-phase catalytic oxidation in the 2-hydroxy-3,5-di-tert-butylbenzyl alcohol-MnO₂-NaOH system to yield 2-hydroxy-3,5-di-tert-butylbenzaldehyde was carried out. Gaseous oxygen participates in the regeneration of the active form of the oxidant.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1833–1834, October, 1994.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 94-03-08653).