Study of the kinetics of bacterial synthesis of iron minerals by Mössbauer spectroscopy

The kinetics of formation of iron-containing minerals by thermophilic dissimilatory iron-reducing bacteria (strain Z-0001) under controlled laboratory conditions has been investigated by Mössbauer spectroscopy. The content of Fe(III) hydroxide that is used by bacteria as an electron acceptor was 90 mmol l^?1 and the percentages of CO₂ and N₂ in the gas phase were, respectively, 20 and 80%. The Mössbauer measurements were performed at room and low (77 and 4.2 K) temperatures and in a magnetic field of 6 T. It is established that the Fe(III) hydroxide reduction by bacteria occurs in several stages with the formation of a mixture of nonstoichiometric magnetite and maghemite.     

Absorption of atmospheric oxygen by agitated weakly alkaline solutions of surfactants

Volumetric analysis of the decomposition kinetics of sodium hydroxymethylsulfinate was performed to study the absorption of atmospheric oxygen by surfactant solutions agitated in various modes at 353 K. The application of the Danchwerts model of surface renewal made it possible to evaluate the contribution made by changes in driving forces in the stages of O₂ absorption and solvation to the overall effect of accelerated gas absorption. The intensifying influence of surfactants on the process of oxygen absorption, manifested in an immobile fluid and at slow solution agitation rates, is eliminated by the oppositely directed changes in the mass transfer and solubility of oxygen at the phase boundary in the transition and turbulent flow modes.     

M?ssbauer study of compounds of Cu3 ? xFexSnS4 and Cu2Fe1 ?xZnxSnS4 systems

A M?ssbauer study of the structural and charge states of ⁵⁷Fe and ¹¹⁹Sn atoms in the compounds of Cu_{3 −x} Fe _x SnS₄ and Cu₂Fe_{1 − x} Zn _x SnS₄ systems was performed. It was shown that the iron atoms in the compounds of both systems were in the divalent and trivalent states occupying the tetrahedral positions of the structure. The character of the changes of the degree of covalency of the Fe²⁺-S, Fe³⁺-S and Sn⁴⁺-S bonds during the isomorphic substitution in the systems was established.     

Investigation of iron mineral formation by dissimilatory alcalophilic bacterium Geoalkalibacter ferrihydriticus using M?ssbauer spectroscopy

Formation of iron-bearing minerals by the dissimilatory alcalophilic bacterium Geoalkalibacter ferrihydriticus (strain Z-0531) under controlled laboratory conditions was studied using M?ssbauer spectroscopy. Strain Z-0531 was isolated from bottom sediments of Lake Khadyn (Tyva, Russia), a soda lake. The effect of the concentration of amorphous iron hydroxide (AFH) and anthraquinone-2,6-disulfonate (quinone) added to the medium was studied along with the effect of the incubation time on iron reduction.     

Features of the plasma saturation of nanocrystalline and coarse-crystalline titanium samples with hydrogen and deuterium

We investigate the laws governing the saturation of nano- and coarse-crystalline Ti-6Al-4V alloy samples with hydrogen from high-frequency and glow discharge plasmas with a view to finding materials suitable for making hydrogen accumulators. We conclude that nanocrystalline Ti-6Al-4V alloy holds promise for creating hydrogen accumulators, and hydrogen plasma of high-frequency discharge origin is a cleaner hydrogen saturation medium than that of non-self-sustained discharge origin.     

Change in the Space Potential in Glow Discharge Plasma during the Motion of the Shock Wave

Technical Physics - It has been established in experiments on the interaction of a shock wave with a glow discharge that the motion of the shock wave is accompanied by an increase in the potential...     

Investigations of sulfide minerals with layered structure by Mössbauer spectroscopy methods

Samples obtained as a result of the tochilinite synthesis process were investigated by ⁵⁷Fe Mössbauer spectroscopy. Tochilinite, magnetite and troilite were obtained in investigated samples. The dependences of phase relative content on different content of Mg atoms in the initial mixture were received. It was found that Mg atoms stabilized tochilinite structure. It was shown that magnesium atom entering into tochilinite structure led to Fe atom redistribution in brucite-like layer. It was confirmed that in tochilinite structure equal number of sulfide and brucite-like layers conjugated.