Symmetries and Interaction coefficients of Kelvin waves

We considered symmetry restriction on the interaction coefficients of Kelvin waves and demonstrated that linear in small wave vector asymptotic is not forbidden, as one can expect by naive reasoning.Comment: 4 pages, submitted to J. of Low Temp. Phy

The composition and structure of iron(III) complex compounds with salicylic acid in ethanol solution and in the solid thin film state

Owing to their properties iron(III) salicylate complexes are interest of for application in biomedicine and environmental monitoring. Recently this complex compounds also are investigated as a potential candidate for preparing Fe2O3 films by sol-gel method from ethanol film-forming solution. Relevance of the work was caused by necessity to determine the structure and composition of iron(III) salicylate complexes in ethanol solution and in the solid film state, which influence on film properties. Nowadays this information is absence in the literature. UV spectroscopy, NMR measurement, methods of isomolar series and thermal analysis were used to analyze the composition of complex in ethanol solution and in the solid state. It was found, that salicylic acid interacts with iron(III) chloride in ethanol solution promotes the formation of [FeC6H4OCOO]+ complex, where salicylate ligand behaves as bidentate ligand. After removal of the solvent from solution iron(III) chloride salicylate crystal hydrate complex of 1:1 stoichiometry was formed in solid state. Thermal decomposition of this compound led to formation α–Fe2O3

Microwave-assisted hydrothermal process for the preparation of SnO from an ammoniacal Sn6O4(OH)4 suspension

SnO powder with a specific surface area of 2 m2/g has been prepared by microwave-assisted hydrothermal processing of an ammoniacal Sn6O4(OH)4 suspension. We have examined the effect of pressure rise rate in a reaction mixture on the surface morphology and photocatalytic activity of SnO. Raising the pressure has been shown to reduce the SnO synthesis time, without influencing the surface morphology of SnO or its photocatalytic activity for methyl orange photodegradation

Photocatalytic activity of titania nanopowders prepared by a sol–gel process at various pHs

A strategy has been proposed to prepare photocatalytically active titania nanopowders through a sol-gel route using high-degree molecular separation upon the dilution of reagents, high water/alkoxide ratios, high reagent mixing rates, and pH effects. This strategy has been successfully used to isolate, from sols, anatase powders with high surface areas (100–310 m2/g) dependent on the pH value during the synthesis. The photocatalytic activity of titania nanopowders prepared by the sol-gel process at various pHs has been tested in photodestruction of organic dyes (Rodamine B, Methylene Blue, and Anthraquinone AcidBlue) in acid solutions. UV-radiation-induced dye destruction rates are found to depend on the surface properties (including surface area and ζ potential) and hydration specifics of the titania

TiO2-NiO and TiO2-Co3O4 spheres: synthesis and characterization

TiO2-based composites doped with d-metal oxides are prospective catalysts. In this paper we obtained spherical particles of TiO2–NiO and TiO2–Co3O4 composites by a template method accompanied with sol-gel one. Ion exchange resin of TOKEM-100 and TOKEM-250 was used as an organic polymer matrix. Complex studies were carried out to identify the formation process, compositions and morphology of obtained particles by thermal analysis, X-ray diffractometey, scanning electron microscopy and micro-X-ray spectral analyses The formation of TiO2–Co3O4 and TiO2–NiO composite particles ends at 600 and 500°C, respectively at using TOKEM-100 and TOKEM-250 resins. The size of final spherical particles found to be in a range from 300 to 700 μm, and their morphology depends on its compositio

Synthesis and investigation of physico-chemical, antibacterial, biomymetic properties of silver and zinc containing hydroxyapatite

In the work we carried out microwave synthesis of modified hydroxyapatites (HA) with different content of ions. A solid solution based on HA remains a single-phase sample when the calcium ions are substituted by silver and zinc ions up to 5 % by weight (0.5 mole fraction). The microstructure parameters, morphology and the particle powders size were studied by X-ray diffraction analysis, IR spectroscopy, and scanning electron microscopy (SEM). It is shown that the modification of НA by silver (AgHA) and zinc (ZnHA) ions increases the size of its particles, the degree of crystallinity, and the pore sizes of the samples while reducing their specific surface and uniformity of their forms. Elemental analysis and distribution of elements over the surface of HA, AgHA, and ZnHA powders were performed by X-ray spectral microanalysis (RSMA). The ratio of Ca/P is within the range of 1.66-1.77 and corresponds to the ratio of Ca/P in stoichiometric HA and the HA entering bone tissue. The ability of AgHA- and ZnHA-substrates to form on their surface a calcium-phosphate layer from the simulated body fluid (SBF) at 37 °C is determined. This ability decreases in the order: in ZnHА it is less than in AgHА, but greater than in HА. The antibacterial activity of the samples was analyzed. The AgHA sample has both bactericidal and persistent bacteriostatic properties in the case of direct contact with Escherichia coli cells

Preparation of composite materials based on hydroxyapatite and lactide and glycolide copolymer

Composite materials for the restoration of bone tissues based on hydroxyapatite and a copolymer of lactide and glycolide were obtained. The composition of materials at different stages of production is estimated by X-Ray diffraction method. It has been established that during the production of materials a new phase of chlorine-substituted hydroxyapatite (Ca9.7(P6O23.81)Cl2.35(OH)2.01) was formed, which promoted an increase of hydroxyapatite solubility in the composition of materials. The quantitative estimation of micro- and macroporosity of materials is given. It was found that the use of sodium chloride as the pore-forming agent delivers porosity of the composites required for use as bone substitutes

Synthesis and properties of spherical catalysts TiO2-SiO2/МхOy (M = Co and Cr)

Layered spherical materials were obtained, the inner layer of which is represented by oxides of cobalt or chromium, and external oxides of titanium and silicon. D-metals were fixed on the surface of the polymer substrate through sorption from aqueous solutions of the corresponding salts. The outer layer of the oxide titanium-silicon matrix was obtained by the sol-gel method. Aggregative stability of sols was controlled by viscosimetry. The influence of the components on the stability of sol solutions has been established. The time interval for the stability of sols is in the range of 400-1000 h. The laminated structure, material characteristics are studied using 3D-microtomography. The catalytic activity of the obtained TiO2-SiO2/Cr2O3 and TiO2-SiO2/Co3O4 samples was compared to the n-heptane oxidation reaction. The maximum heptane conversion for the TiO2-SiO2/Co3O4 sample is 80 % at a temperature of 600 °C, for the TiO2-SiO2/Cr2O3 sample, the conversion of n-heptane reaches 100 % at 400 °C