Thermal dissolution of oil shale in benzene with an ethanol additive under supercritical conditions

The results of the thermal dissolution of oil shale from some deposits in Russia in a benzene solvent under supercritical conditions in a semiflow system are reported. It was found that the addition of ethanol significantly increased the yield of liquid products due to the hydrogenating and alkylating properties of the alcohol.     

Antioxidant activity of phytogenous industrial waste and derived extracts for the production of feed and food additives

Organic wastes as well as their ethanolic, water and heptane extracts and fermented products derived from herbs, fruit and vegetables obtained worldwide from food and pharmaceutical industries were investigated regarding their antioxidant activities using different methods [1.1‐diphenyl‐2‐picrylhydrazyl, Fe^III‐reduction method and photochemiluminescence (PCL)]. The highest antioxidative activities were exhibited by different products of grape seed wastes (350–830 mg rosmarinic acid equivalent g^?1 dried material = rae g^?1 dm) followed by ethanolic extracts of blueberry (475 mg rae g^?1 dm), larch (219 mg rae g^?1 dm), willow (193 mg rae g^?1 dm) and sunflower presscake (154 mg rae g^?1 dm). Ethanolic extracts of the residues showed comparatively higher activity than water extracts. The least antioxidative capacities were found in heptane extracts of serenoa products (0.4; 0.6 mg rae g^?1 dm) and fermented waste of carrots (1.6 mg rae g^?1 dm). Correlating different assay methods, the strongest correlation was found between Fe^III‐reduction and DPPH‐method (correlation coefficient r² = 0.99**) and the weakest between Fe^III‐reduction and PCL method (r² = 0.57**) for raw materials.     

Unstrained epitaxial InxGa1−x As films obtained on porous GaAs

Epitaxial layers of InGaAs solid solutions were grown on porous GaAs(100) substrates by liquid-phase epitaxy. A comparison between the compositions and thicknesses of these epitaxial layers with those of layers obtained under the same conditions on normal monolithic GaAs substrates suggests that the crystallization of epitaxial layers on porous substrates may be considered as the growth of free unstrained films. Pis’ma Zh. Tekh. Fiz. 25, 15–20 (November 12, 1999)     

Ferroelectric properties of LC systems including chiral dopants with different molecular structure

Abstract— New ferroelectric liquid crystals (FLCs) on the basis of the eutectic mixture of phenylbenzoate derivatives including chiral components (CCs) with a different number and position of carbonyl groups in their molecular core have been investigated. The ferroelectric characteristics such as the spontaneous polarization, smectic tilt angle, rotational viscosity, and repolarization time as well as their concentration dependences are analyzed. On the basis of the previous and obtained results, the influence of peculiarities of the molecular structure of CCs on mentioned properties of FLCs are generalized.     

Dielectric and magnetic properties,NEXAFS spectroscopy of Co-doped of multicomponent bismuth niobate pyrochlore

Two series of Bi₂Mg_1-xCo_xNb₂O₉ and Bi₂MgNb_2-2xCo_2xO_9-δ preparations with pyrochlore structure were synthesized using solid phase method. It was found that solid solutions are formed in Bi₂MgNb_2-2xCo_2xO_9-δ series, foreign phases of MgNb₂O₆ and Bi₅Nb₃O₁₅ are fixed in Bi₂Mg_1-xCo_xNb₂O₉ samples, no impurity cobalt-containing phases were detected. The method of magnetic susceptibility and NEXAFS-spectroscopy investigated the electronic state and character of exchange interactions of cobalt atoms in solid solutions with the pyrochlore structure. According to X-ray spectroscopy and magnetic susceptibility of cobalt atoms in solid solutions in a dominant amount are in the charge state of Co(II) in the form of monomers and exchange-bound clusters mainly with antiferromagnetic type of exchange. Ceramics Co-doping of multicomponent bismuth niobate pyrochlore has at room temperature a high dielectric permeability of 84 and small dielectric losses of 0.001. The energy of activation of conductivity is equal to 0.75–1.03 eV. This type of ceramics with excellent dielectric properties can potentially be used as multilayer ceramic capacitors.     

Modelling of the mechanical response of Zr–Nb and Ti–Nb alloys in a wide temperature range

International Journal of Mechanics and Materials in Design - This article presents the results of modeling the mechanical behavior of Zr–Nb and Ti–Nb alloys in a range of strain rates...     

Stoichiometry and doping effects on cation ordering in LiNbO3 crystals

The cation disorder in stoichiometric and congruent lithium niobate crystals and also in congruent crystals doped with Y³⁺ or Gd³⁺ has been studied by X-ray diffraction and Raman scattering spectroscopy using vacancy models. The results indicate that the structural disordering induced by doping with Y³⁺, revealed by both X-ray diffraction and Raman spectroscopy, can be understood in terms of the mechanism of yttrium incorporation into the cation sublattice of the crystal. Yttrium substitution for Nb⁵⁺ on its normal lattice site causes Nb⁵⁺ to occupy vacant octahedra, thereby increasing the cation and vacancy disorder along the polar axis and distorting the octahedra because the ionic radius of Y³⁺ exceeds that of Nb⁵⁺.