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Quasistationary approximation is formulated for the problem of stimulated Brillouin scattering (SBS) in air, which is considered as a multimode acoustic medium. In the approach suggested, the equation for the envelope of the complex amplitude of the light field is solved numerically. On the basis of numerical experiments, it is ascertained that when powerful laser radiation λ = 1.315 μm is propagating in air, the SBS effect can lead, at a sufficient power, to a significant increase in the angular divergence of laser beams.

Results of simulation of the impulse response of an atmospheric optical communication channel on scattered radiation at wavelengths of 0.3, 0.5, and 0.9 mm are considered. Our analysis shows that the maximal power of the received information-bearing signal is attained at λ = 0.3 mm for base distances between the source and the receiving system of 2-3 km and shorter. For larger base distances and low atmospheric turbidity, the maximum is attained at λ = 0.5 μm. When the atmospheric turbidity is high and the base distances are 3-10 km, the maximal power is observed at λ = 0.5 μm. However, when the base distances exceed 10 km, the maximal power of information-bearing signal is attained at λ = 0.9 μm. For a particular example of laser source and receiver system, the limiting base distance between the source and the receiver and the limiting pulse repetition frequency which is not filtered out by the communication channel are estimated using the results of calculations of the impulse response of the atmospheric communication channel at λ = 0.5 μm.

Possibilities of retrieving the asymmetry factor of the atmospheric aerosol phase function from spectral measurements of light extinction and scattering are analyzed. An empirical formula for parameterization of the relation between the asymmetry factor and Ångström exponent and complex refractive index has been suggested. Several approaches to the determination of the asymmetry factor from data of integrating nephelometers are considered. An empirical relation connecting the asymmetry factor with the ratio of the scattered radiation into forward and backward hemispheres has been derived. Using the data of field measurements in Saint Petersburg suburbs in 2015, the asymmetry factor has been calculated at three wavelengths.

Specific features of scattering and absorption of laser radiation by an ensemble of two identical microcapsules are theoretically investigated. Each capsule is modelled by a two-layered spherical micron-sized particle consisting of water core and light absorbing polymer shell. By virtue of the numerical electrodynamics technique it is shown that the internal particles structure, as well as their mutual arrangement affect the character of the spatial distribution and amplitude characteristics of the power absorbed. The highest values of the absorbed power density in the microcapsule dimer could be achieved if the particles are displaced relative to each other by a distance of about diameter (strongly absorbing particles) or if the particles are in the geometric shadow of each other (weak absorption).

The first estimates of a contribution of midges into extinction of optical radiation for background conditions of summer in Western Siberia are received. Values of the midges extinction coefficient received on the basis of experimental data on a wavelength of 1.06 mm change from 0 to 0.14 km^-1. The estimate of the mean value of midges extinction coefficient in visible and infrared regions makes 0.07 km^-1. It is shown that the relative contribution of midges into extinction coefficient of optical radiation in the 0.5-16 mm is essential and changes on average from 26 to 63%.

Positive and negative effects of non–additivity of oxygen absorption rates at oxidation of Na₂S in the presence (Ni^II + Co^II)–containing catalysts were detected. It was determined that these effects were associated with peculiarities of the formation of nickel and cobalt sulphides particles. Positive effects of non–additivity were observed in the beginning of the reaction at the stage of forming metals sulphides embryos and referred to synergistic phenomena. Negative effects were detected at the growth stage of the sulphide phase particles. They are of nonsynergistic nature and associated with deposition of nickel sulphides on the surface of cobalt sulphide particles.

The effect of the catalytic addition of mesoporous aluminosilicate on the composition of the cracking products of natural bitumen on the Ashalchi deposit with a content of IBP-200 °C fractions of 4.6 mass % in the autoclave reactor was studied. It was demonstrated that the addition of 5 % catalyst increased destruction of resins and the yield of low-boiling fractions. It was determined that the catalyst modification with nanoscale nickel powder slowed down coke formation. At cracking of bitumen employing mesoporous aluminosilicate modified with nickel, the yield of IBP-360 °C fractions per 35.2 mass % was increased, and destruction of resins and asphaltenes was 48 % in comparison with the initial bitumen.

Homogeneous nitrogen doped (N-CNTs) bamboo-like carbon nanotubes with the carbon content up to 7.3 at % were obtained by catalytic decomposition of ordinary ethylene/ammonia mixture. Physicochemical properties of N-CNTs were studied by X-ray analysis, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy methods. The effect of the synthesis temperature, catalyst nature and reaction mixture composition per the amount of nitrogen, ratio of its forms, defectiveness and morphology of N-CNTs was determined.

The effect of reduction temperature of a Pt/WO₃/ZrO₂ catalyst (200–500 °С) on indicators of n-heptane isomerisation was studied. It was found that the maximum yield of the desired reaction products that are high-octane di- and trimethyl-substituted (DTMS) n-heptane isomers was reached (27–31 mass %) in the region of the 250–300 °С. A rise in reduction temperature of the catalyst to 400–500 °С leads to an increase in the number of Lewis acid sites in 1.6–1.7 due to partial reduction of tungsten on the WO₃/ZrO₂ surface, which contributes to an increase in the catalyst activity; herewith, selectivity by the target products decreases due to enhancing side reactions of n-heptane cracking.

The study results of acidity in a series of borate-containing aluminium oxide with the B₂O₃ content from 2.0 to 31.4 mass % (butenes oligomerisation catalyst) and a nickel-containing ethane oligomerisation catalyst obtained on its base were presented using the ESR spin probe method. The correlations between catalytic properties and the amount of nickel adsorbed with the concentration of Brønsted acid sites (BAS) determined using the probe molecules perylene were found: an increase in the concentration of BAS determinable with perylene in systems leads to a rise in the butenes conversion degree, the yield of oligomerisation products, and also to an increase in the amount of nickel adsorbed.