Carotenoids of the ascidianHalocynthia aurantium

It has been established that the main components of the carotenoid fraction of an extract ofHalocynthia aurantium are astaxanthin and diatoxanthin, the latter possessing a weak antioxidant activity. No prenylated hydroquinones, which are characteristic for colonial species of ascidians were detected in the four species of solitary ascidians from the Sea of Japan investigated.     

Determination of phenolic components in ethanolic extracts from wood of Maackia amurensis

The phenolic components in an ethanolic extract from the wood of Amur maackia were determined quantitatively by the HPLC method in the isocratic regime using a column with a C₁₉ reversed-phase sorbent and β-naphthol acetate as internal standard. Before injection into the chromatographic column, the extract was purified on a column of Florisil that had been treated with 30% acetic acid. The relative error in the determination of each component at a confidence level of 0.95 does not exceed 7%.     

Studies of V?Mo?O systems with small vanadium content in acrolein oxidation

A solid solution of vanadium in MoO₃ with a solubility limit of about 3 mol.% V₂O₅ is shown to be formed. Its catalytic properties are discussed.

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MoO₃ 3 . % V₂O₅ .

     

Phlomoside D — an iridoid glycoside fromPhlomis regelii

A new iridoid – phlomoside D- has been isolated from the epigeal organs ofPhlomis regelii (M. Pop). Its structure has been established on the basis of chemical transformations and spectral characteristics.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 551–553, July–August, 1996. Original article submitted February 5, 1996.     

A study of complexation of chloral hydrate with heteropoly anions having various structures

¹H NMR was applied to study the interaction of chloral hydrate in deuterionitrobenzene solution with tetrabutylammonium salts of the heteropoly acids (HPA) belonging to five structural types: Keggin (H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀, H₄SiW₁₂O₄₀), Dawson (-H₆P₂W₁₈O₆₂, -H₆P₂Mo₁₈O₆₂, -H₄S₂Mo₁₈O₆₂), H₆P₂W₂₁O₇₁(H₂O)₃, H₆As₂W₂₁O₆₉(H₂O), and H₂₁B₃W₃₉O₁₃₂. The surface of the HPA anions is nonuniform in acid-base properties. A general rule for all HPA was found, namely, that the HPA acidity increases with a decrease in the specific anion charge (per W or Mo atom).     

Dimethyl- and Diethyltin(IV) Compounds with Perfluorobiphenyl-4-Thiolate and Perfluoronaphthalene-2-Thiolate Anions: The Crystal Structure of (CH3)2Sn(C12F9S)2

Compounds (CH₃)₂Sn(C₁₂F₉S)₂ (I), (CH₃)₂Sn(C₁₀F₇S)₂ (II), and (C₂H₅)₂Sn(C₁₀F₇S)₂ (III) were synthesized. Single crystals of Iwere grown and structurally characterized using X-ray diffraction analysis (1590 reflections, R = 0.0209). The crystals are orthorhombic, a = 40.848(8) Å, b = 6.058(1) Å, c = 11.183(2) Å, V = 2767(1) ų, (calcd.) = 2.024 g/cm³, space group Pbcn, Z = 4. The structure is built from monomeric molecules. The coordination polyhedron of the Sn atom (the SnC₂S₂ core) is a distorted tetrahedron. Compounds I–III are volatile when heated in vacuo. Thermolysis of these compounds results in SnO₂ (in air) or SnS₂ (in argon).     

Plasma-assisted oxidative degradation of organic dyes in solution by the joint action of underwater discharge and ozone

Data on the degradation kinetics of two organic dyes in a mixture by the action of electrical underwater discharges and ozone are presented. It has been found that the rate of degradation by the to combined treatment of the both dyes with face discharge and ozone is five times the sum of degradation rates expected on the assumption of the additive effect of each of these factors.     

Natural convection in a closed parallelepiped with a local energy source

An experimental and numerical analysis was performed to investigate the laminar regimes of conjugate thermogravitational convection in a closed parallelepiped with heat-conducting walls of finite thickness in the presence of a local energy source with convective heat exchange with the environment. The numerical studies were performed using the Fluent software. The experimental data and numerical results agree well each other.