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In the process of developing deposits of magnetite quartzites, hematite quartzites are simultaneously involved in mining. But the processing of hematite quartzites is associated with significant difficulties, so they accumulate in warehouses, landfills and spread uncontrollably in the environment. A detailed study of the features of the composition, structure and technological properties of hematite ores made it possible to develop a new method for complex processing in a vortex air-mineral flow. Under laboratory conditions, a number of commercial products were produced from them: iron ore concentrate, sinter ore, clinker ore, mineral paint and quartz sand, without waste accumulation. The formation of magnetic floccules is reduced in the air stream. Therefore, this technology also improves the processing of magnetite ores.

Glass-like epoxy-titanium oxide composites were obtained using amine curing and sol-gel method for the formation of nanofiller from titanium tetra-n-butoxide directly in the polymer binder. As a polymer matrix of the composites, the product of polycondensation of low-viscosity epoxy resin ST-3000 and polyetheramine Jeffamine T-403 was used. The titanium dioxide content in the composites was 0.5–10 wt %. The structure of the obtained composites was studied by Raman spectroscopy and electron microscopy, and a detailed thermomechanical analysis of the samples was performed. The titanium oxide nanofiller forms a three-dimensional network in the organic polymer matrix, and such an inorganic framework reinforces the polymer. With an increase in TiO 2 concentration, the temperature of the beginning and the temperature of completion of the transition of the composites to a highly elastic state significantly increase. The mass-fractal structural organization of titanium dioxide in the composites determines the lower deformability of the samples. Interphase transition layers with different segmental mobility were detected in the structure of the composites. In these layers, during the formation of epoxy-titanium oxide composites, filler/matrix interaction occurs with the formation of chemical covalent bonds. The features of the composites’ structure affect the operational properties, in particular, the protective properties of coatings based on them. It was established that thin composite coatings can provide corrosion resistance of 315 kΩ cm 2 on the surface of the D16 aluminum alloy. The efficiency of corrosion protection of the substrate was 70–90%, depending on the filler concentration in the coatings.

The work was aimed to study the synergy of the antimicrobial activity of the prodigiosin pigment with antibiotics against bacteria of the genera Bacillus, Staphylococcus and Streptococcus. The serial dilution method was used to evaluate antimicrobial compositions, which included inhibitors of cell wall synthesis: ampicillin, benzylpenicillin, vancomycin, cefazolin, and metronidazole (nitroimidazole derivatives) in combination with the pigment prodigiosin isolated from Serratia marcescens. Each combination was tested against the studied strains. The fractional inhibitory concentration index (FICI) for each combination was calculated to determine synergy, and the results were interpreted as follows: FICI <0.5 - synergism; FICI> 4.0 - antagonism; and FICI> 0.5-4 - neutralism. It was shown that the ethanol extract of prodigiosin in combination with benzylpenicillin, vancomycin, cefazolin, and metronidazole interacted differently synergistically depending on the type of microorganism. The combinations of prodigiosin and metronidazole showed a synergistic effect against Bacillus subtilis, vancomycin and cefazolin against Staphylococcus aureus and benzylpenicillin against Streptococcus pyogenes. Other combinations of prodigiosin and antibiotics showed a neutral effect, and in the case of cefazolin against Str.pyogenes, even an antagonistic effect. Thus, the study showed the synergism of prodigiosin with antibiotics depending on the type of microorganism, contributed to a several-fold decrease in the minimum inhibitory and bactericidal concentrations of each component separately, and the results indicated that prodigiosin acted separately more efficiently against gram-positive non-spore-forming bacteria. This synergistic combination of antimicrobial agents had great potency to prevent bacterial resistance

Purpose The purpose of this paper is to minimize and prevent current overloads (including the elimination of abnormal and fire hazardous situations) in photovoltaic solar arrays by using low-cost functional electronic elements, in particular, the new PolySwitch PPTC fuses. Design/methodology/approach The modeling method has been used to investigate the circuit solution of the use of PolySwitch type fuses to prevent and minimize current overloads in photovoltaic solar arrays. Findings It is shown that the limitation of the short-circuit current with parallel connection of photovoltaic components (photovoltaic cells or their modules) can be implemented when the following conditions are met: the resistance of the fuse in the conducting state is much lesser than the parallel connection of the series resistances of the photovoltaic components; and the tripping current of the fuse must be greater than the maximum current of the separate photovoltaic components and lesser than the current of a parallel connection of several photovoltaic components. Originality/value The influence of the magnitude of the resistance in the conducting state and the response current of the fuses to the current–voltage and volt–watt characteristics of parallel connections of the photovoltaic components (photovoltaic cells or their modules) is analyzed. The modeling results are confirmed by experimental data on the transformation research of light current–voltage and volt–watt characteristics of parallel connections of industrial photovoltaic modules using resettable fuses of the PolySwitch type.

Modern alluvium is a complex multicomponent system that includes both natural and man-made material. In the process of research on the pollution of river sediments with industrial waste, the authors established the presence of commercial products of mining and processing enterprises in the sediments. It includes crushed granite, metallurgical slags, ores and concentrates, coal and other products. Significant volumes of inputs of these materials into the ecosystem motivate the development of special technologies aimed at additional production of mineral products through the complex processing of modern river alluvium. In addition to economic benefits, the implementation of these projects will improve the state of the environment in regions with significant technogenic load.

Purpose. To choose the optimal dose of the natural mineral glauconite in combination with cationic flocculant to extract phenols and rhodanides from industrial effluents. To substantiate the advantages of using natural glauconite as an adsorbent with a developed cationic ability to absorb toxic substances. To develop a mathematical model of the adsorption treatment of phenolic wastewater at a flotation plant. Methodology. Chemical studies were carried out according to the methods of V. M. Kagasov, E. K. Derbisheva. When conducting experiments to determine the concentration of phenols in industrial effluents, a photometric method was used, based on the formation of red-colored phenol compounds with 4-aminoantipyrine in the presence of potassium hexacyanoferrate. To establish the concentration of thiocyanates in phenolic wastewater, a photometric method was used, based on the interaction of the rhodanides ion in an acidic medium with iron (III) chloride ions. The determination of the optical density of the solutions was carried out on a concentration KFK-2 photocolorimeter with subsequent use of calibration graphs. Findings. It was experimentally shown that when applying the interval of doses of glauconite 2-6 g/dm3, an effective purification of liquid waste from phenols is achieved as well as a decrease in the concentration of the initial phenolic water from 510 to 330390 mg/dm3 in the time interval of 110-140 min at the mechanical stage. A decrease in the maximum permissible concentration (MPC) of phenols in the initial wastewater of a coke chemical plant has been achieved, regulated - not more than 415 mg/dm3. The process of purification of industrial effluents from rhodanides with the selection of the optimal dose of adsorbent using mathematical processing of experimental data, which amounted to 2-3.5 g/dm3 with flotation duration of 120 min, was studied. The initial concentration reduction of rhodanides from 475.2 to 328-348 mg/dm3 was obtained. The MPC of rhodanides, with a norm of not more than 400 mg/dm3 before biological treatment was reached. Originality. The process of sorption removal of phenols and rhodanides from liquid wastes with different doses of glauconite to describe a mathematical model of the adsorption process was studied. For the first time, kinetic regularities of the process of phenol extraction from wastewater by glauconite in an amount of 2-8 g/dm3 in combination with a cationic flocculant with a volume of 5 ml/dm3 in a time interval of 20-120 min were established. The opportunity to predict the optimal dose of adsorbent, to influence the time of the sorption process and reduce the content of polluting agents to environmentally friendly indicators was obtained. Practical value. A mathematical description of the process of purification of phenolic wastewater using glauconite is given. Based on the description of the mathematical model, for industrial implementation, it is proposed to use the natural adsorbent glauconite in the optimal dose range of 2-6 g/dm3 in combination with a cationic flocculant in an amount of 5 ml/dm3 with optimal adsorption process duration of 110-140 min.

This article presents the results of the stress-strain state modelling of a blood pump diaphragm manufacturing from polyurethane 'Vitur' T-1413-85 for pulsatile type Ventricle Assist Device systems. Based on the analysis of the most distributed models of hyperelasticity, a model which most accurately describes the behaviour of the specified material has been determined (R2 = 0.9999 between numerical simulation and experimental uniaxial tensile tests data). Experimental studies have been carried out to determine the displacement of the diaphragm with a thickness of 0.3 mm and 0.5mm under the influence of control pressure. A comparison of the modelling results of the blood pump diaphragm stress-strain state and the conducted experimental studies on the determination of displacements confirmed the adequacy of the chosen model (R2 = 0.96 between numerical simulation and experiment) for both of the studied diaphragm thickness.

We present here the results of mathematical modeling of the process of thrombus formation in the chamber of a blood pump from a pulsatile-type circulation assist system with an output of 30 cm3 using two types of Russian- made mechanical heart valves. The effects of the type of mechanical heart valve on thrombus formation in the blood pump chamber during operation of the pulsatile-type circulation assist system were assessed.

In the work, we present results of the mathematical modeling of hemodynamic processes of a system of auxiliary blood circulation (ABC) of pulsatile type with an ejection volume of 30 cm3 and two types of domestic mechanical heart valves. We show the influence of the type of inlet valve and the angle of its orientation on hemodynamic processes that occur during the operation of the blood pump. On the basis of results obtained, we give recommendations for the selection of the type of valve and its spatial arrangement in order to ensure optimal blood flow and minimization of stagnant zones inside the chamber of the blood pump.

The paper presents the results of calculation of the normalized index of hemolysis using three different approaches based on mathematical modeling of a pulsatile circulatory support system with a stroke volume of 30 cm3. The suggested approaches are shown to be useful for estimating the hemolysis level in pulsatile circulatory support systems at various stages of the design process.