Dependence of the solubility of atmospheric oxygen in weakly alkaline aqueous solutions on surfactant concentration

The solubility of atmospheric oxygen in solutions of surfactants of different natures at 293 K and pH 8 is determined by gas chromatography. It is found that additives of nonionic surfactants decrease the oxygen content in the solution in the premicellar region and increase its solubility in the micellar region. It is shown that, for anionic surfactants, a decrease in the solubility of O₂ is observed over the entire concentration range.     

Efficiency of the use of two-photon absorption in impurity liquid crystals as a mechanism of optical limitation

An analysis is made of the advantages of impurity liquid-crystal systems that are associated with the existence of the excitonic mechanism of electronic excitation energy transfer in them. Using the two-photon absorption in such systems, one can substantially expand the dynamic range of optical limitation.     

An experimental and theoretical study of shock-wave propagation through reactive gases under conditions causing a transformation of the flow structure

Experimental observations of the transformation of the structure of shock waves entering the discharge gap of either a transverse or decaying glow discharge are presented. It is found that the total impulse of the shock wave pressure remains constant. A variation in the speed of sound, that is, the shock wave velocity, at which total dispersion of the wave occurs is found to be nonmonotonous across the discharge gap. The times over which the wave structure keeps changing after switching off the discharge have been more accurately determined. On the basis of the obtained experimental data and earlier results, a conclusion on the mechanism of this effect has been drawn. This mechanism is related to the dispersion of disturbances making up the wave structure in a relaxing medium (such as the glow discharge plasma). On the basis of a theory of this kind of dispersion, using the experimental data, and comparing energetic and temporal characteristics of the internal states of the plasma under study and the mode of sound disturbances (which according to the experiment, are responsible for the effect), we have succeeded in determining the O₂(a ¹Δ_g) state whose relaxation brings about this effect.     

Mössbauer and magnetic studies of nanocomposites containing iron oxides and humic acids

A sample of volcanic ashes emanated from the Osorno volcano, southern Chile, was characterized with X-ray fluorescence, X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy, in an attempt to identify the iron-bearing minerals of that geologically recent magmatic deposit. X-ray patterns indicated that the sample is mainly constituted of anorthite, Fe-diopside-type and Ca-magnetite. The crystallographic structures of these dominant iron minerals are proposed on basis of their chemical composition and corresponding Mössbauer data to support models refined by fitting powder X-ray diffraction data with the Rietveld algorithm.     

Ellipsometry of tetragonal lead oxide single crystals

The refractive index of PbO tetragonal single crystals ($\text{n}\text{?}{}_0\text{= 2.73±0.05}$) and parameters of thin dielectric film on their real surfaces (n_f = 1.56±0.01, $\text{d = 10?85}\text{A}\text{?}$) have been measured by the method of ellipsometry at $\text{λ = 6328}\text{A}\text{?}$. For the first time the photo-induced changes of optical properties of PbO^(t) surface film have been observed.     

Numerical Simulation of the Stress Concentration in an Elastic Half-Space with a Two-Layer Inclusion

The stress concentration around a two-layered spherical inclusion located near the surface of an elastic half-space under uniform compression is considered. A numerical solution algorithm is elaborated, application software is created, and numerical experiments demonstrating the capabilities of the approach proposed are conducted.     

Features of pectin biodegradation in the presence of sodium ethylenediaminetetraacetate

We have studied the effect of sodium ethylenediaminetetraacetate on enzyme-induced degradation of apple pectin. Capillary viscometry and IR spectroscopy data have shown that the ligand binds Ca²⁺ ions (present in pectin) thus accelerating its biodegradation 1.2–1.6 times at relatively low concentration of the complexone. At the same time, sodium ethylenediaminetetraacetate reduces enzymatic activity of lytic enzymes thus slowing down pectin hydrolysis as higher concentration of the complexone.     

Mössbauer Study of Magnetite Formation by Iron- and Sulfate-Reducing Bacteria

Hyperfine Interactions - Mössbauer investigations of the influence of physicochemical factors and the inert organic substances on the magnetite formation by thermophilic dissimilatory...     

Scattering of optical radiation by fog water droplets

The behavior of local optical characteristics of an aerosol medium in the radiation field of a microsecond-pulse CO₂ laser is experimentally investigated. Using measurements of the scattering intensity of a sounding beam, the dynamics behind the formation of a propagation channel over the interaction time is studied for different energy densities, and the characteristic times over which the channel is clouding and clearing, the dimensions of the explosion products, and the degree of their evaporation are established. Scattering of radiation in the visual range by shock waves is observed that is caused by the gas-dynamic explosion of fog droplets.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 79–84, February, 1987.     

Transformation of hydrometeors in mists during their explosion by an intense laser pulse

A model of intense laser radiation propagation in hydrometeors is investigated. It is shown on the basis of the interaction between a laser radiation pulse and an individual aerosol particle that hydrometeors subjected to intense radiation are transformed into mean density mists which degrade the propagation conditions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 34–39, March, 1980.