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A review of experimental results obtained with the participation of the authors of this article, as well as in other studies on the generation and development of localized perturbations in two- and three-dimensional boundary layers, is presented. The accompanying wave phenomena and the contribution due to the spatial-temporal deformations of the velocity field of the initial laminar flow to its transition into turbulent state in boundary layers on the surface of aircraft, including small unmanned aerial vehicles (UAVs), are discussed.

The paper presents the results of numerical simulation of starting conditions for a supersonic air intake using the bypass of part of the captured air flow through longitudinal slots. The air-intake duct consists of a tapered inlet section and a constant-cross-section throat built using flat surfaces, and it contains longitudinal bypass slots stretching along the flat bottom surface. Various types of the sectional bypass of the air flow are investigated, and the change of the air-intake-duct flow structure depending on the flow bypass mode is demonstrated. Numerical modeling of the three-dimensional flow was performed for free-stream Mach number M_∞ = 4 on the basis of Reynolds-averaged Navier-Stokes equations and the κ-ω SST model of turbulence.

The paper presents a systematic view for a swirl flow produced within a cylindrical container with fixed walls and a rotating top lid using two theoretical approaches: the lattice Boltzmann equations and Navier-Stokes equations. The flow modes for this confined liquid flow were tested as functions of two parameters: Reynolds number and the cylinder height to radius ratio. The lattice convergence of both solutions was analyzed. The simulation data exhibit compliance between these two variants and with the available experimental data, including the case of the development of recirculation flow at the cylinder axis (which corresponds to the event of vortex breakdown).

Comparative analysis of the macro and trace element composition of fruit, leaves and stems of the plants was carried out with respect to the content of mineral nutrition elements in the soils in the natural population of the Altai subspecies of blue honeysuckle (Lonicera caerulea subsp. altaica) in the local zone where disjunctive geological structures are concentrated in the valley of the Kyzyl-Yaryk river (the Altai Mountains, the North Chuya Ridge). Substantial variations of the total content of macro and trace elements Ca, Al, K, Na, Sr, P, Mn, Ba, B, Zn, Cu, Cr and Ni, the mobile forms of Ca, Sr, Fe, Mn, Cu, Cr, Ni, Co, Na in the soils and soil acidity (pH 4.5-6.7) were revealed at the regions differing from each other in the volume activity of radon emission field (262-1162 Bq/m³). Micropopulations of L. caerulea subsp. altaica at these regions differed from each other in the level of accumulation of Сu, K, P, Na, Mo, Cr, P, Sr, Si in plant organs, and in the physiologically essential ratios Cu/Zn, Fe/Mn and K/Ca. An increase in the Cu/Zn ratio in plant organs had a significant effect on a decrease in fruit size, number of seeds in fruit, their germination capacity, and an increase in the seed germination power. The seed germination power is also in significant positive correlation with the level of Ca, Mg, Cr, Cu, Sr, Pb accumulation in leaves and stems, and with the Fe/Cu ratio. The content of K in fruit is in significant negative correlation with seed germination power.

A new cyclopropane-containing optically transparent copolymer has been obtained by radical copolymerization of 4-(2-carboxycyclopropyl)styrene (CCPS) with acrylonitrile (AN), and its characterization was carried out. The structural peculiarities of the obtained polymer and the basic regularities of the studied process are investigated, the useful properties of the obtained compound are revealed, and the possible areas of its practical use are considered. It is established by means of turbidimetric analysis that the obtained polymer products are true copolymers, and not a mixture of two homopolymers. It is shown that copolymerization reactions proceed with opening of the double bond of the vinyl group in CCPS and AN. Copolymerization constants are measured ( r ₁ = 0.7 and r₂ = 0.15), Q-e Alfrey-Price parameters ( Q ₁ = 0.267, е₁ = -0.30) and microstructures of the copolymer are determined. During radical copolymerization, CCPS shows higher activity in comparison with AN. It is revealed from the microstructural parameters of the copolymer of CCPS with AN that the minimal blocking occurs in the range of M₁ / M₂ ~ (50 : 50)-(25 : 75), where M₁, M₂ are the fractions of CCPS and AN, respectively, mol. %. It is revealed that the radical copolymerization of CCPS with AN in the bulk allows obtaining the polymer with high purity in comparison with copolymerization of the monomers in the benzene solution. For obtaining the copolymer with the highest light transmission, comonomer ratio CCPS/AN should be 75 : 25 mol. %. The physical-mechanical, thermophysical, optical properties of the obtained copolymer are determined. In comparison with polystyrene and the copolymer of styrene with AN, the synthesized new copolymer possesses higher heat resistance, tensile strength and water absorption. It is established that the synthesized copolymer samples are characterized by good light transmission (87 %) and optical transparency ( n_D²⁰ = 1.5898). The copolymer of CCPS with AN possesses higher light transmission and refraction index than the copolymer of styrene with AN. The change rate of the light transmission index of copolymer of CCPS with AN depending on the composition of the synthesized polymer is investigated.

Coke formation process is studied by the example of SARA fractions - saturated (S) and aromatic (A) hydrocarbons, resins (R) and asphaltenes (A) - naphthenic and methane crude oils by means of thermogravimetry. The studied oil samples are characterized as heavy, high-sulphur, high-resin and contain large amounts of asphaltenes. They differ from each other in the content of resins, asphaltenes, sulphur, and in the yields of fractions with the initial boiling point (IBP) 360 ^оC. Thermogravimetric analysis was carried out heating the samples from 25 to 650 C at a rate of 10 C/min in argon. It is demonstrated that the yield of coke-like condensation products (coke) depends on the composition and structure of SARA fractions. During thermal analysis, the yield of coke is lower from the fractions of saturated and aromatic hydrocarbons and resins of naphthenic oil than from similar fractions of methane oil. The amount of solid products formed during thermal analysis of asphaltenes from naphthenic oil is larger than for asphaltenes of methane oil. Experimental and calculation data on coke yield from thermal analysis of model mixtures are presented. It is determined that coke formation during thermal analysis of model mixtures is not a direct function of the additive contribution from each of the components of the mixture.

Application of activated carbon (AC) obtained from cotton wastes (bolls, stems, and roots) for phenol adsorption from water, or wastewater dephenolization, is presented. The kinetics of phenol adsorption by carbon adsorbents were studied using UV/Vis spectrophotometer. The porosity of the formed ACs ranged from 1.952 to 2.339 cm³/g, the volume of macropores was from 1.79 to 2.09 cm³/g, while the commercial sample BAU-A showed 1.920 and 1.320 cm³/g, respectively. The highest phenol adsorption rate, 32.49-52.80 mg/(g•min), was observed for contact time up to 5 min on carbon adsorbents obtained from cotton waste. The adsorption equilibrium was achieved within 5 min after the contact, which is shorter than the analogous commercial adsorbents (7-12 min). Sufficiently high phenol adsorption activity of AC from cotton stems, roots and bolls is revealed. Therefore, the use of AC from cotton wastes as adsorbents for the treatment of industrial wastewater to remove organic and other impurities can be recommended for environmental remediation applications.

An urgent direction of the fuel and energy industry is the development of methods for vegetable oil and hydrocarbon co-processing in order to produce low-freezing and environmentally friendly components for diesel fuel. Zeolites of different structures and modifications are becoming increasingly popular as catalysts for these processes. Processing of the straight-run diesel fuel and a mixture of diesel fuel with 10 vol. % sunflower oil has been carried out over a zeolite catalyst of ZSM-5 type at a pressure of 0.35 MPa, feed rate 0.5 h^-1 and two different temperature points: 375 and 475 °C. Regularities of temperature effect and the influence of sunflower oil involvement into processing over zeolite catalyst on the composition and properties of the products are determined. These regularities are shown to depend on process temperature. It is established that the products of diesel fuel co-processing with sunflower oil over the zeolite catalyst at 375 °C correspond in their low-temperature characteristics to the Arctic grade of commercial diesel fuel, and at 475 °C - to the winder grade of commercial diesel fuel. It is demonstrated that the products of processing over the zeolite catalyst are promising components of low-freezing fuel. The results provide evidence that co-processing of diesel fraction and sunflower oil over the zeolite catalyst is promising for obtaining low-freezing components of engine fuel. The involvement of sunflower oil will expand the feedstock pool for fuel production.

Microcystin-producing culture of benthic cyanobacterium Tychonema sp. BBK16 isolated from biofilm fouling of the coastal zone of Lake Baikal is described for the first time. The pink colour of the trichomes and the developed keritomy of the cells indicate belonging to the genus Tychonema . Investigation of the morphology and the fragment of the 16S RNA gene showed the uniqueness of this type of cyanobacteria, the closest relative of the new species being the rheophilic cyanobacterium Tychonema sp. K27 from the karstwater stream. At the phylogenetic tree, together they form a separate clade of benthic attached forms. It is determined that the Baikal strain of Tychonema sp. BBK16 produces microcystin LR and does not synthesize anatoxin, which distinguishes it from the previously described species. This ability was revealed in vitro on media with Baikal bottled water and with wastewater from sewage treatment plant of Vydrino settlement. The addition of purified wastewater to the medium enhances the metabolism of cyanobacteria and results in an increase in the concentration of microcystin LR to 320 μg/g of dry weight. Assimilation of the additional amount of biogenic and organic substances by cyanobacteria has a stimulating effect on their metabolism. Analyzing the emergence of cyanobacteria of Tychonema genus in Lake Baikal, we assume that these bacteria undergo mass development in places of excess intake of nutrients, in particular those of organic origin.

Nanostructured composite material is obtained on the basis of multiwall carbon nanotubes filled with the products of thermal decomposition of cobalt complexes with disodium salt of ethylenediaminetetraacetic acid (Trilon B) - CoH₂Y. The performed characterization of the composite shows that the content of cobalt in it is consistent with that assigned during the synthesis, and sodium chloride obtained as a by-product is almost completely removed by washing. The consistent results of cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance measurements reveal a noticeable increase in the electrical capacity of the carbon matrix in the region of low scanning rates with the introduction of a filler (up to 1.8 times at a rate of 10 mV/s), which is associated with the occurrence of relatively inertial electrode Red-Ox processes like CoO ↔ CoO _х (OH) _у ↔ Со₂О₃ ↔ Со₃О₄ under these conditions. At high potential scanning rates, the introduction of small amounts of filler (less than 5%) has practically no effect on charge accumulation. With an increase in filler content, a symbate decrease in the capacity is observed, which is likely associated with an increasing blocking of the nanotube surface and a decrease in the capacity due to the formation of an electric double layer, while the Red-Ox reactions with the participation of the filler do not occur under these conditions due to relatively low rates. The results of impedance and galvanostatic measurements are consistent with this model.