Low-Temperature Crystal Growth in Aqueous Systems

The conditions for the crystal growth of various substances (salts, amino acids, and others) in aqueous systems between the eutectic (0°C) and room temperatures were studied. The ingots prepared by freezing solutions of required compositions were used as source material for crystal growth (recrystallization). The growth and properties of the crystals were shown to be controlled by the supersaturation which is maintained at the desired level by means of fractional ingot melting.     

Synthetic nanostructured wollastonite: Composition,structure and “in vitro” biocompatibility investigation

This article describes an original sol-gel (template) method for the synthesis of a dispersed form of nanostructured wollastonite (CaSiO₃), its gold nanoparticles (40–60 nm) functionalized form CaSiO₃/Au-NPs, and its composite in the composition with 20 mass% of hydroxyapatite CaSiO₃/HAp and synthetic hydroxyapatite, that are widely used in medicine for the reconstruction and regeneration of bone defects. The method provides the formation of porous silica carcass in samples with an average pore size of 100–160 nm due to the application of polymer siloxane-acrylate as a pore-forming template. The authors studied the processes of template destruction and phase formation in the composition of samples using TGA/DTA/DSC (thermogravimetric analysis/differential thermal analysis/differential scanning calorimetry), and XRD (X-ray diffraction analysis). The methods of SEM (scanning electron microscopy), low-temperature nitrogen adsorption, and mercury porosimetry were used to identify the morphology and study the structural characteristics (S_spec and V_por, pore size distribution) for dispersed nanostructured samples based on wollastonite and hydroxyapatite. An “in vitro” model was used to study the functional activity (metabolism and cytokine production) of innate immune cells (neutrophils and macrophages) in contact with the obtained samples and to evaluate the viability of cells, the activity of ATPase activity, the number of cationic proteins, and apoptosis of cells. The study is novel for these systems and contributes to the existing knowledge on the biocompatibility for “in vivo” model, which provides a complex evaluation of the quality of wollastonite biomaterials used as grafts.     

Method for measuring the weight concentration of O-pinacolyl methyl phosphonate in soil,snow, and loose materials using advanced sampling devices

New technical solutions are proposed for sampling soil, snow, and loose materials with improved operating characteristics that may be used in measuring the weight concentration of O-pinacolyl methyl phosphonate in ecological, geological, geochemical, and microbiological research. Translated from Izmeritel’naya Tekhnika, No. 4, pp. 68–71, April, 2009.     

A method of measuring the mass concentration of arsenic in water with the development of a promising sampler

A method of measuring the mass concentration of arsenic in water is considered. New samplers with improved operating characteristics for ecological monitoring of aqueous media are proposed.     

Role of vapor flow in the mechanism of levitation of a droplet-cluster dissipative structure

The rate of water evaporation has been experimentally determined under conditions that ensure the formation of a dissipative structure of the droplet cluster type [1, 2]. It is shown that, in the region of localization of a droplet cluster, the velocity of the vapor-air flow is sufficient to maintain the levitation of droplets over the liquid surface according to the Stokes mechanism.     

Method for measuring the weight concentration of O-isobutyl methyl phosphonate with development of advanced sampling devices

A method is considered for measuring the weight concentration of O-isobutyl methyl phosphonate in air, and new engineering solutions are proposed for a sampling device with improved operating characteristics for ecological monitoring of the atmosphere. Translated from Izmeritel’naya Tekhnika, No. 5, pp. 68–72, May, 2009.     

Nanostructured Magnetic Sorbents for Selective Recovery of Uranium(VI) from Aqueous Solutions

Direct sol-gel, novel template, and additional high-temperature reduction procedures for preparing iron oxides and their composites, showing promise for selective sorption of dissolved U(VI) from aqueous media of various acidities, are described. The sorption activity of the materials was studied, the kinetic curves of the sorption were obtained, and the efficiency of the selective recovery of U(VI) from aqueous solutions with different pH values using the new sorbents was compared. The probable mechanism of the U(VI) sorption onto the sorbents studied was suggested on the basis of SEM, XPS, emf, and BET data. The quantitative sorption of U(VI) is determined to a greater extent by the composition of the sorbent solid phase, rather then by the specific surface area of the sorbents, which ranges from 0.1 to 47.3 m² g^?1 depending on the synthesis procedure. The crystalline Fe⁰ phase in the sorbents prepared using additional high-temperature reduction plays the key role in the U(VI) sorption by the reducing deposition mechanism. The saturation magnetization for this type of sorbents can reach 133–140 emu g^?1, which is an additional advantage allowing magnetic separation of the spent sorbents from the treated solutions.

     

Structure relaxation and crystallization of the CoW-CoNiW-NiW electrodeposited alloys

The structure of electrolytically deposited nanocrystalline alloys of the CoW-CoNiW-NiW systems under low-temperature heating was investigated by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), and analytical methods such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Structural relaxation and crystallization were investigated at temperatures of 200°C to 300°C. The structural and compositional inhomogeneities were found in the CoW-CoNiW-NiW alloys, while the local changes in composition were found to reach 18 at.%. Nanocrystals in the alloys grew most intensely in the presence of a free surface, and we found their nuclei density to range from 2 × 10²³ /m³ to 3 × 10²³ /m³. It was determined that the local diffusion coefficient ranged from 0.9 to 1.7 10⁻¹⁸ m²/s, which could be explained by the prevalence of surface diffusion. The data gathered in these investigations can be used to predict the thermal stability of CoW-CoNiW-NiW alloys.