The presented review addresses the prospects for application of organochalcogen compounds in various fields of technology, medicine, agriculture and organic synthesis. The unsaturated chalcogenisation products appear to be of much greater interest compared to their saturated analogues, especially in organic synthesis. This study observes halogen derivatives of ethene, propene, propyne and butene subjected to chalcogenisation as unsaturated substrates. The indicated reagents are related either to large-tonnage products of industrial organochlorine synthesis or waste products of organochlorine production with their disposal presenting an important environmental task. According to analysed publications, chalcogenisation processes are based on the application of elemental chalcogens (sulphur, selenium, and tellurium) or their available metal derivatives (Na2S, etc.). In the reactions of chalcogens with unsaturated halogen derivatives, the elements both in an accessible form and in a free state are subjected to reductive activation resulting in the formation of anionic nucleophilic reagents. Complex metal hydrides, chalcogenide anions and rongalite are exampled for application in terms of reducing agents. The review emphasises the prospects of basic reduction systems based on hydrazine hydrate in activation processes. Special aspects in the introduction of caustic alkalis and an monoethanolamine organic amine as bases in these systems are described. For the considered chalcogenisation processes, conditions are specified providing the most optimal yield of certain products. In some particular cases, the stereochemistry of the obtained compounds is presented considering the formation conditions for the stereoisomers of a certain configuration. For a number of the obtained compounds, the prospects of practical application are provided. In general, the current review is intended for specialists working in the field of organic synthesis and application of organochalcogen compounds.

The authors declare no conflict of interests regarding the publication of this article.

Polycarboxylic acids are involved in many life processes, along with germatranes exhibiting high biological activity. At the same time, the studies on the reactions of 1-substituted germatranes with polycarboxylic acids appear to be insufficient. On the one hand, compounds of germatranes with substances containing a car boxyl group were reported to be stable in the presence of water. On the other hand, the germatranic cycle of 1-germatranol hydrate in an aqueous medium is acknowledged to be decomposed by D-tartaric acid to bis(µ-tartrato)di(hydroxy)germanate(IV) triethanolammonium form. In this work, the interaction of 1-germatranol hydrate (H₂O·НОGe(OCH₂CH₂)₃N) with oxalic acid (HOC(O)COOH) in water, dimethyl sulphoxide and acetonitrile alcohol was studied. The reaction in an aqueous medium at 20–25 °С quickly leads to the cleavage of the germatrane skeleton followed by the formation of [(C₂O₄)2Ge(OH)₂] ^2- ·H⁺ ·[(HOCH₂CH₂)₃NH]⁺ bis(oxalate-O,O') dihydroxygermanate triethanolammonium. As a result of the topochemical reaction, exposing the reaction residue following evaporation of water at 50 °С in a vacuum of 2 mm Hg for 2 h subsequently leads to the formation of (ROC(O)COOGe(OCH₂CH₂)₃N(R=H) and N(CH₂CH₂O)₃Ge mono- and bis(germatran-1-yl)oxalate), as well as to the reduction of 1-germatranol. Under additional exposure of the reaction mixture in a 2 mm Hg vacuum at 100 °C for 40 min, O[Ge(OCH₂CH2)₃N]₂ bis(germatran-1-yl)oxide and (germatran-1-yl)formate is formed. Following the water dissolution of the reaction mixtures, the resulting compounds undergo another conversion to bis(oxalate-O,O')dihydroxygermanate triethanolammonium and 1-germatranol. Heating a mixture of 1-germatranol hydrate with oxalic acid in a dimethyl sulphoxide and acetonitrile medium along with 1-germatranyl oxalates leads to the formation of a hydrolytic cleavage product of the germatrane skeleton, bis(oxalate-O,O')dihydroxygermanate triethanolammonium, while the boiling of isoamyl alcohol mainly provides for the esterification reaction with a 1-isoamyloxygermatrane yield exceeding 90 %.

The development of methods and techniques for protecting the surfaces of steel structure exposed to aggressive environments, e.g. sea water, presents itself as an urgent task in material science. One of the directions in solving these problems involves the application of paints and enamels based on organic binders. The promising aspects of this direction are due to the possibilities of creating compositions by varying the physicochemical properties and colloidal chemical qualities of the components – film formers, binders, pigments and fillers. In this study, properties of protective coatings based on acrylic latex are examined together with their dependency on anti-corrosion additives and pigments using the corrosion test methods described in a number of state standards. In the corrosion test programme, an EDX-800HS X-ray spectrometer (Shimadzu, Japan), ShS 80-01 SPU oven and an HR-150AZ analytical balance with weighing accuracy up to ±0.0001 g were applied in conjunction with a number of other modern instruments. The application of acrylic latex based on butyl acrylate ester monomers and styrene as a protective coating was proved to be ineffective in the case of metal surfaces subjected to aggressive action. The work provides the compositions optimal in terms of chemical formula, dispersion and quantitative ratios and possible to significantly increase the protective ability of anticorrosion coatings. The addition of a pigment based on zinc phosphate and sodium nitrite as an anti-corrosion additive to the composition of the Rzhavostop acrylic enamel significantly increases the protective properties of the composition. The enamel-coated samples of St3 steel exhibit no signs of corrosion for up to 2–3 days of maintaining in model solutions of sea water. The enrichment of Rzhavostop acrylic enamel with black pigment with at least 95 % of 3-di(2-hydroxyethylamino) propionic acid 2-ethylhexyl ester greatly enhances the effect of the film former adhering to the metal surface. The addition of zinc tetraoxychromate complements the effect and prevents corrosion from spreading over the surface. In 7–8 days, no signs of corrosion were detected in St3 steel samples of under the considered conditions.

The authors declare no conflict of interests regarding the publication of this article.

In aqueous and non-aqueous solutions of strong and weak electrolytes, complex interparticle and intermolecular interactions occur mainly between charged particles, solvent molecules, as well as between ions and solvent dipoles. Depending on the properties of the solvent, the same dissolved electrolyte may exhibit opposite properties. So, for example, acetic acid, weak in water, when interacting with a more protogenic solvent (liquid hydrogen fluoride) exhibits the properties of a base by accepting a proton. This behaviour is understood to be determined by the difference in proton affinity. However, insufficient information has been published on the quantitative characteristics of interactions in solutions of strong and weak electrolytes. The present article considers these processes taking place in dimethylformamide (DMF). The most requested electrolyte solution parameters are evaluated: the solvation number of some ions, as well as the masses and sizes of solvated ions. The calculated values are proved to be consistent with those in the literature data. The thermodynamic constants of diphenic acid dissociation in DMF were determined and calculated using the multilevel modelling method for the energy of hydrogen bonds in solvents, thus accounting for dipolar proton solvents (including DMF). Parameters calculated according to the multilevel modelling equations are shown to be consistent with the known literature. The method of multilevel modelling was used to calculate the energy and dimensional characteristics of ions and chemical compounds, as well as the characteristics of ionisation, heat capacity, critical properties and the isothermal differences of thermodynamic functions from the ideal state of solvents. Calculation methods were developed for predicting and refining the parameters of chemical, biological, medical and other systems, supplemented by constructed models concerning state of the ions in solution.

The authors declare no conflict of interests regarding the publication of this article.

The reaction of catalytic hydrogenation involving hydrogen transfer through unsaturated C = C and C = O bonds in organic compounds in the presence of optically active soluble complexes of transition metals with nitrogen-containing multidentate ligands has recently gained increased popularity. This review is aimed at generalising available information on the most effective and promising metal complex catalysts for asymmetric hydrogenation involving hydrogen transfer, which have been proposed in the past 10–15 years. Since the activity and selectivity of catalysts based on transition metal complexes are largely dependent on their composition and structure, the design of ligands, the presence or absence of stereogenic centres, the stability and configuration of the chelating ligand system, the nature of the dentate atoms present therein are extremely important. Researchers worldwide have been largely focused on the synthesis and use such ligands, as optically active diamines and aminoalcohols with sp3 -hybridized dentate atoms. These compositions are not oxidized in the coordination sphere of transition metals compared to phosphine ligands, at the same time as maintaining a high level of stereogenicity. Optically active ligands with sp2 nitrogen atoms containing the C = N azomethine bond and oxazoline fragments have been considered as a separate group. In complexes with transition metals, these ligands exhibit a high stability in the catalytic hydrogenation reaction with hydrogen transfer. The stereoselectivity of catalysts in some cases increases with an increase in the denticity of nitrogen-containing ligands. Among them are N-heterocyclic N, H, C–ligands in the Rh (III) complexes; Ru (II) complexes with tridentate N, N, N–ligands with chiral oxazoline fragments; C, N, N–ruthenium complexes. In this review, we grouped catalysts by ligand denticity (from 2 to 6). Comparative data on the activity of various catalysts and the stereoselectivity of respective reactions is provided. The effect of the structure of chiral ligands on the catalytic characteristics of metal complexes is discussed.

The authors declare no conflict of interests regarding the publication of this article.

According to numerous studies, lactic acid bacteria are characterised by the capability of reducing their initial activity given an insufficient quantity of growth factors supplied by a nutrient medium. Conversely, the introduction of additional sources of nutrient into the medium provides favourable conditions for the development of lactic acid-producing microorganisms. The present study was aimed at examining the effect of phosphorus-containing salts on the biosynthetic activity of a specially selected strain of lactic acid bacteria for the biotransformation of acid whey lactose into lactate-containing ingredients. For this purpose, lactic acid bacteria of the Lactobacillus acidophilus thermophilic bacilli subgroup applied in cheese and fermented dairy production were used as a producer of lactic acid. In the obtained fermented solutions, the mass fractions of lactose and calcium lactate were determined by the Bertrand method and complexometric techniques, respectively. The variables in the biosynthetic activity study of lactic acid bacteria included the type of phosphoruscontaining salt (disodium phosphate dodecahydrate and disubstituted ammonium phosphate) and its mass fraction, which ranged from 1.0 to 3.0 % in increments of 0.5 %. The amount of inoculum introduced for maximum production of lactic acid comprised 2.5 % vol. of the nutrient medium. The titratable acidity of the inoculum ranged from 1.80 to 1.85 g/cm3 . In order to produce calcium lactate, the lactic acid accumulating during biosynthesis was neutralised with chalk. The effect caused by the type of phosphorus-containing salt and its mass fraction on the coefficient of whey bioconversion to lactic acid by L. аcidophilus AT-I lactic acid bacteria was evaluated along with the rate of formation and yield of calcium lactate. The 2.0 % additive of sodium phosphate disubstituted dodecahydrate was established to provide the highest values for the formation rate and yield of the target product, comprising 0.78 g/(dm3 ·h) and 79.96 %, respectively.

The authors declare no conflict of interests regarding the publication of this article.

The article presents a study into the effect of long-term, low-temperature (-80 and -150 °С) storage on the properties of Streptomyces lucensis RNCIM As-1743 and Streptomyces violaceus RNCIM As-1734 actinomycete collection strains acting as producers of glycosidase inhibitors. The titre (CFU in 1 cm3 of the initial inoculum) and the inhibitory activity of strains were determined with respect to pancr eatic α-amylase in the solutions obtained by Streptomyces culture on a corn starch hydrolysate. For Streptomyces, a high survival rate (91–100 %) was established after storage at temperatures of -80 and -150 °C using a 15 % glycerol solution in terms of a cryoprotector. Streptomyces violaceus strain was identified to be the most resistant to long-term storage at low temperatures. Its inhibitory activity turns to be completely retained after storage at temperatures of -80 and -150 °С. In Streptomyces violaceus strain, the maximum activity level of 2250±200 IU/cm3 for an inhibitor of pancreatic α-amylase is observed on the 1st day of subculture, while Streptomyces lucensis RNCIM As-1743 demonstrates the highest activity value on the 3rd day to reach a value of 3660±200 IU/cm3 following storage at a temperature of -80 °С. The studied Streptomyces strains are chromogenic. The most intense chromogenesis is noted during the culture of Streptomyces violaceus strain stored at a temperature of -150 °С. The cryopreservation of Streptomyces violaceus and Streptomyces lucensis actinomycete strains was established to provide high (107 –108 ) cell survival and preservation of their inhibitory activity at a high level when exposed to temperatures of -80 and -150 °С with a 15 % glycerol solution as a cryoprotector. Experimental data indicate the low-temperature storage method to be promising for Streptomyces lucensis and Streptomyces violaceus collection cultures.

The authors declare no conflict of interests regarding the publication of this article.

Cellulose-containing raw materials are currently considered to be among the most promising types of raw materials for the production of value-added bio-products. However, for the implementation of the developed process, the application of universal pre-processing methods is a prerequisite. In the present paper, a study into the bioconversion of oat hull and miscanthus cellulose samples by enzymatic hydrolysis into glucose solutions is presented. The substrates were obtained by two-stage processing of raw materials with dilute solutions of nitric acid and sodium hydroxide. Enzymatic hydrolysis was carried out using the Cellolux-A and Ultraflo Core enzyme preparations at an initial substrate concentration of 40 g/L. At the first stage, the reactivity of the substrates to enzymatic hydrolysis in an acetate buffer solution was studied over a period of 72 hours. Cellulose samples from both types of raw materials were established to possess equally high reactivity in terms of the reducing substances. Glucose obtained from the substrate yielded 94–95 % and 88–91 %, respectively. This indicates the universality of the pre-treatment method used for raw materials having a cellulose content of 35–45 %. At the second stage, hydrolysis of the substrates was carried out using a pilot fermenter in an aqueous medium with an excess of enzyme preparations. Over a period of 32 hours, aqueous hydrolysates were obtained with a concentration of reducing substances and glucose equal to 42 g/L (94 % yield from the substrate) and 33–35 g/L (74–78 % yield from the substrate), respectively. The glucose (79–83 %) and pentose (1–2 %) content of the reducing substances indicates glucose to predominate in the composition of the resulting solutions. The high bioconversion efficiency rate is additionally demonstrated by a comparative analysis of scanning electron spectroscopy results for substrates and residues following hydrolysis in a pilot fermenter. Glucose solutions obtained in an aqueous medium are emerging as promising materials for the preparation of culture media and the synthesis of valuable metabolites.

The authors declare no conflict of interests regarding the publication of this article.

The discovery of antibacterial preparations (ABP) in the form of antibiotics has an almost 100-year history. During this time, both the flourishing of their effectiveness against many pathogenic bacteria and the currently emergence of multidrug resistance (MDR) to them have been noted. This review analyses the results of studies conducted by many international laboratories involved in the development of both new antibiotics and other forms of antibacterial drugs. Contemporary approaches are presented in the field of nanotechnology, genomic and postgenomic technologies with their application contributing to the creation of new ABPs. By virtue of these technologies, the first results have been obtained on the application of molecular peptides and nanoparticles in terms of ABPs, acting lytically on the bacterial membrane. In recent years, bacteriophage viruses and their combinations have again been actively used as ABPs to fight superbacteria, while data on their ability to lyse pathogens have been obtained. In addition, an analysis was provided of the results for bacteria metabolic studies provided for the creation of the iChip chip design for high-performance culturing of bacteria in their natural habitat, while opening the access to "uncultured" microorganisms. In a number of studies also based on metabolic methods, the results are presented for the identification of "uncultured" microorganisms directly from the metagenomes. This approach allows them to be further cloned and expressed into the genomes of the prototyped bacteria. According to the authors, this allows for rapid selection of new molecules for use as antibiotics. The main conclusion of this review consists in the necessity of studying the "superbacteria" formation mechanisms for both MDR factors and their interaction with the cells of the human body. In general, given the extensive scientific research on the creation of new ABPs, the future does not look so threatening to humanity in the fight against "superbacteria".

The authors declare no conflict of interests regarding the publication of this article.

The conversion of household and industrial wastes containing lignocellulose into a variety of target products (bioenergy sources, organic acids, sweeteners, etc.) involves one of the priority directions for the state environmental policy of the Russian Federation. However, the profitability of processing the substrates obtained by hydrolysis of such secondary sources of raw materials is determined by the possibility of microbiological utilisation for not only hexoses (D-glucose, D-mannose, D-galactose), but also pentose (D-xylose, L-arabinose). The aim of this review consists in a discussion of the prospects for using microorganisms in the disposal of lignocellulose pentoses, along with problems arising in the course of the technological implementation of this process. The review provides contemporary data on the spectrum of pro- and eukaryotic microorganisms ensuring the destruction of lignocellulose and the utilisation of its structural components in natural ecosystems. A brief description of action mechanism inherited to the enzymes of ligninase, cellulase and hemicellulase complexes is presented. The main problems hindering the enzymatic hydrolysis application to multicomponent household and industrial lignocellulose wastes are identified. The factors determining the selectivity of pentosis catabolism in mycelial fungi, bacteria and yeast are examined. The spectrum of target products in bioconversion of lignocellulose pentoses, is determined with regard of their economic importance. The methods of complex microbiological utilisation of various household and agricultural wastes, as well as the possibility of involving by-products from industrial destruction of wood (acid hydrolysates and sulphite liquors) in this process, are discussed.

The authors declare no conflict of interests regarding the publication of this article.

The development of methods for pest management continued to be one of the main directions in development of biotechnology throughout the twentieth century. In Russia, the development of this research area is inextricably linked with the name of Evgeny V. Talalayev, professor of Irkutsk State University and the founder of the biological forest protection approach. Though his enterprise, theoretical foundations for the use of the microbiomethod were developed, along with the first domestic bacterial preparation against the Siberian silkworm, dendrobacillin. Large-scale tests of the preparation were carried out to demonstrate its safety in terms of human health. With his direct participation, industrial production of biological products was organised in the USSR. These products were in great demand in both domestic and foreign markets. The article gives a brief history of the study of the entomopathogenic properties of Bacillus Thuringiensis and the development of biotechnological methods for pest management on its basis. A brief comparative analysis is provided for the current state of microbiomethods for the protection of plant species in Russia and abroad. The results of the first decades of large-scale application in agricultural production based on B. thuringiensis genetic engineering Bt-technologies, positioned as a more effective and economical alternative to the microbiome, are considered. The main reasons for the low efficiency of this area of plant genetic engineering as described in the scientific literature are presented. Additionally, the problem of discounting the development patterns of natural parasitic systems underlying the microbiomethod during the creation of transgenic BT plants is considered. An assessment for the value of the scientific heritage of E.V. Talalayev for the development of plant protection methods based on B. Thuringiensis is made along with the presentation of a number of new directions for the development of plant biotechnologies on their basis. Further prospects for the use of the microbiomethod plant protection approach in the Russian Federation are discussed.

The authors declare no conflict of interests regarding the publication of this article.

Issues associated with waste disposal all over the world, including in Russia, determine the urgency in applying biopolymers as environmentally-friendly packaging materials. Nowadays, the development of technologies and formulations of biodegradable films based on domestic ingredients for application in the packaging of food and/or pharmaceutical products is of a great relevance. Biodegradable polymers based on natural polysaccharides possess certain advantages over plastics, especially in terms of their complete and rapid degradability under natural and/or specially-created conditions. When developing the technology for producing packaging materials, including food production, special attention is paid to the characteristics of the resulting packaging, which is responsible for preserving the initial qualities of both the packaging and the product for a certain time, at least until delivered to the consumer. Therefore, low oxygen and water vapour permeability manifests itself as a special property of biodegradable films, having particular importance for food packaging applications. Formulations of biodegradable film samples obtained from compositions of natural polysaccharides (hydroxypropyl methylcellulose, carrageenan and agar-agar) are proposed and studies on their main properties (degree of biodegradation, gas permeability, water absorption, chemical resistance, degradation and toxicological properties) carried out. Based on the results of the study, compositions appropriate for application as the basis for environmentally friendly packaging materials for food and pharmaceutical products were selected. The maximum stability of the studied films (i.e., the period of their complete dissolution) in concentrated hydrochloric, sulphuric and acetic acids was determined. The considered samples of biodegradable films were proved to cause no toxic effects on natural ecosystems.

The authors declare no conflict of interests regarding the publication of this article.

The study is aimed at improving the microsprout regeneration method for the 'Suvenir Oseni' and 'Yuzhnaya Krasavitsa' Diospyros kaki (persimmon) cultivars of the Nikitsky Botanical Gardens. The breeding of and optimising the conditions for non-stop 12-month in vitro deposition of kaki persimmon was carried out for the purpose of creating a gene bank of valuable subtropical crops. The explanting of in vitro culture and the regeneration of persimmon microsprouts was carried out in the laboratory of plant biotechnology and virology of the "Nikitsky Botanical Gardens" National Scientific Centre RAS. For regeneration of microsprouts, Murashige and Skoog medium (MSO) containing 6-benzylapinopurin (BAP) and 3-(1,2,3-Thiadiazolin-5)- 1-phenylurea (TDZ) growth regulators was used. In order to ensure in vitro preservation, microsprout segments were placed in a nutrient medium composed by ¼ of normal MS, sucrose and chlorocholinchloride (CCC). The culture vessels were placed in refrigerators to maintain a low positive temperature (4–14 °С). In the course of the experiments, the inducing role of BAP (2–4 mg/L) in the MS nutrient medium at the induction stage of spout formation was established to ensure stable direct regeneration of microsprouts from the vegetative burgeons of kaki persimmon. The maximum number of normal microsprouts having no visible changes was obtained in MS medium having a BAP concentration of 4 mg/L and equal to 2.0±0.4 and 2.7±0.4 pcs. for the 'Suvenir Oseni' and 'Yuzhnaya Krasavitsa' cultivars, respectively. The average length of microsprouts reached 1.90±0.04 cm for the 'Suvenir Oseni' cultivar, while, for 'Yuzhnaya Krasavitsa', this value was equal to 3.1±0.07 cm. The presence of TDZ in the MS medium facilitated the formation of microsprouts through indirect organogenesis in the leaf cutting culture of the studied cultivars. The frequency of spout formation from leaf cuttings reached 65–79 % following 6 weeks of cultivation on media with 1.1 and 1.7 mg/L concentration of TDZ. Differences in the morphogenetic potential of explants were traced throughout all stages of development. Data from histological callus studies confirm the presence of proliferatively active cells giving rise to microsprout meristems. The concentration of 60.0 g/L and 0.2–0.4 g/L for sucrose and CCC, respectively, contained in ¼ MS medium was shown to stabilise the viability of persimmon explants at a storage temperature of 8–10 °С for 12 months.

The present work is aimed at studying the biochemical composition of apple fruits growing in the Southern Baikal region, as well as the determining the qualitative characteristics of apple wine obtained by fermentation on wood chips under ultrahigh yeast concentration. The main physicochemical parameters and the total content of phenolic compounds in juices of six apple breeds are determined. For the fruits of 'Krasnoyarskiy Snegirek' variety, the content of macro- and microelements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, Pb and Ba) was analysed by X-ray fluorescence spectrometry. Among the macronutrients, K was established to be presented in the largest amount (0.762 %), while the quantity of Fe (0.006 %) appears to be significantly lower. An increase is detected in the qualitative characteristics of apple wine material during fermentation on wood chips under ultrahigh yeast concentration. The redox potential was shown to have decreased by 80 mV. The tasting score increased by 0.7 points. Additionally, the colour intensity decreased by 0.392 nm and the hue changed by 0.3 nm. The HPLC-UV-MS method was applied to study the change in the composition of phenolic compounds during juice fermentation. Phenolic compounds related to phenolcarboxylic acids (derivatives of aromatic hydrocarbons), derivatives of dihydrochalcones, flavan-3-ols and flavonols were identified in juices and wine materials. As compared to the control, a threefold decrease in the total amount of phenolic compounds during fermentation on wood chips was obtained. The must fermentation rate was confirmed to increase by 72 hours. The possibility of obtaining juices with increased nutritional value and low-oxidised white wines from winter-hardy apple breeds of the Southern Baikal region was demonstrated.

The authors declare no conflict of interests regarding the publication of this article.

 

In the implementation of aerobic biosynthesis processes, the productivity of a bioreactor depends on the intensity of oxygen mass transfer. Disk mixers with a perforated surface, providing an increase in the contact surface of the gas and liquid phases, were studied. The power characteristics of disk mixers with bent segments and sectors was experimentally established to depend on the slope of the working surfaces. For multi-tier mixers, the exponent regarding the number of tiers in the expression of total power was determined to be proportional to the value of the distance between tiers in the range of specified distance equal to 0–1.4 of the diameter of the mixer. At a distance between tiers exceeding the diameter of the mixer by 1.5 or more times, the total power is equal to the sum of the powers of single mixers. The energy efficiency of the process of oxygen mass transfer decreases sharply with decreasing distance between tiers. The eff iciency indicator of the oxygen mass transfer depends on the ratio of aeration and power of the mixer, demonstrated in the form of a saturation curve. An analysis of the obtained experimental dependences supports a conclusion concerning the intensive and energy-efficient process of oxygen mass transfer obtained by ensuring a small ratio of the diameter of the unit to its height, use of multi-tier mixers with a distance between tiers greater than the diameter of the mixer and specific aeration of at least 3 min ^-1 . Perforated disk mixers can be recommended for use in bioreactor designs with the optimal implementation in the processes of aerobic microorganism production, including the cultivation of high-density seed crops. At oxygen mass transfer rates exceeding 10 kgO₂/m³ ·h, modes ensuring the achievement of a high population density of aerobic microorganisms are characterised by relatively low energy efficiency (1–1.2 kg O₂/kWh).

The authors declare no conflict of interests regarding the publication of this article.

The work is devoted to the study of the destruction of the top sphagnum peat layer due to microwave radiation. For the analysis of physical and chemical processes, a laboratory setup was created on the basis of a coaxial resonator-reactor having a geometry that ensures a uniform distribution of the microwave field in the reactor volume. An industrial magnetron having a frequency of 2.45 GHz and a power of up to 1 kW was used as a source of microwave radiation. In laboratory studies with a relatively small amount of peat (~ 100 g), the advantage of the created setup consists in the ability to quickly achieve the necessary temperature for the pyrolysis reaction at a relatively low level of microwave power (~ 100 W) in these experiments. The analysis of the products obtained during the reaction was carried out using a gas chromatography mass spectrometer. The research was aimed at creating highly-efficient environmentallyfriendly technologies for processing biofuels characterised by a high yield of combustible gases suitable for further use in industrial power plants, as well as for obtaining a resinous fraction for the production of light hydrocarbons and a carbon residue for modern highly efficient sorbents. On the basis of the experimental setup, studies were carried out on soft microwave pyrolysis of peat at a temperature of 250 °C under constant removal of gaseous reaction products. Samples of solid, liquid and gas phases presenting valuable carbon residues, oily fractions and a pyrolysis gas, respectively, were obtained and analysed. The article examines the possibility for industrial application of reaction products. The chemical composition of the r eaction products during both microwave and “traditional” pyrolysis with thermal heating is compared. The composition of the gases released during microwave pyrolysis is characterised by the absence of heavy toxic gases often accompanying the process of “traditional” thermal pyrolysis. Reducing the amount of toxic gases improves the environmental component of production. This circumstance indicates the prospects of microwave pyrolysis for industrial processing of organic materials.

The authors declare no conflict of interests regarding the publication of this article.

The current study is aimed at the development of a methodology for calculating hydraulic resistance and the efficiency of cleaning dusty gases with a jet filter dust collector based on experimental data. This dust collector is applied in cleaning dusty gas streams of high concentration by means of a two-stage procedure. At the first stage, in order to minimise dust load, dust particles are deposited under the action of inertial forces arising from the sharp deceleration of a stream. At the second stage, a highly effective purification of the flow is ensured at the level of 98–99 % or more due to the filtering process through the bulk granular layer. Experimental studies of hydraulic resistance and cleaning efficiency of the jet and filter parts of the dust collector affected by jet velocity, nozzle design and its distance to the hopper, dust particle size and density, dust content of the gas flow, as well as dust properties, were carried out. The most significant influence on the increase in hydraulic resistance and the cleaning efficiency of the jet part was established to be exerted by the high-pressure head of the jet, the convergence angle of the nozzle and the shape of the air channel. The optimal limits of the jet velocity, the dimensions of the structural elements of the dust collector are determined, ensuring the efficiency of cleaning the dust and gas stream in the jet part by at least 80 %. Methods were developed for calculating the hydraulic resistance of the jet part of the dust collector based on the coefficients of local resistance, reducer, exhaust and air channel, depending on the density of the gas being cleaned and the average flow rate in the air channel. The hydraulic resistance of the granular filtering partition when clean, as well as during the accumulation of dust sediment, was determined. Based on the law of particle accumulation by a uniform filter as applied to granular layers, a method was developed for calculating the surface and thickness of the filter layer and the duration of the inter-regeneration cycle of the filter.

The authors declare no conflict of interests regarding the publication of this article.

A light scattering study was performed on new silver-containing polymer nanocomposites based on water-soluble copolymers of 1-vinyl-1,2,4-triazole having sodium salt of vinylsulphonic acid of various compositions. The formation of nanocomposites was carried out using chemical reduction of silver ions by sodium borohydride in a copolymer- containing aqueous medium. According to the dynamic light scattering data, a decrease in the average sizes of metal-polymer coils in water-salt solutions of nanocomposites is explained in terms of an increase in the content of sulphonate groups in the stabilising polymer matrix. The electrophoretic light scattering with phase analysis of synthesised nanocomposites reveals the zeta potential (ζ) to vary from -35.0 to -75.3 mV with an increased sulphonate unit proportion in the stabilising polymer matrix, indicating an increase in the stability of the colloidal system. The functional composition of the stabilising polymer matrix is established to provide a significant effect on the hydrodynamic dimensions of polymer nanocomposites in an aqueous medium.

The authors declare no conflict of interests regarding the publication of this article.

At present, the development of environmentally friendly methods for producing biodiesel and the development of new renewable energy sources appears to be an urgent task. The present article reports on a study aimed at assessing the effect of the duration and temperature of sunflower oil processing in sub- and supercritical dimethyl carbonate media on the yield and composition of methyl esters of carboxylic acids. The experiment was carried out using a batch type autoclave in the temperature range of 150–325 °С and an oil : dimethyl carbonate molar ratio equal to 1 : 9. The chemical composition of transesterification products was studied using the GC-MS method. Under subcritical conditions in the range of 150–225 °С, no transesterification of oils practically is detected. An increase in the yield of methyl esters is observed at temperatures above 225 °С with a maximum value of 90.6 % mass identified in the supercritical region at 280 °С. When processed under subcritical conditions for 9 min, the yield of methyl esters does not exceed 80 % of the mass. Along with methyl esters, transesterification products were represented by mono- and diglycerides of fatty acids, methanol, glycerine and the products of glycerine transformations. The content of these products decreased under an increase in temperature. The transesterification product of oil under supercritical conditions is represented by the composition of methyl esters of carboxylic acids. The content of impurities is not more than 1 %. The effect of the treatment duration on the yield of methyl esters is shown to be most pronounced in the subcritical conditions of the process. Under supercritical conditions, more than 80 % of the oil triglycerides are converted to carboxylic acid methyl esters within 3–5 minutes of treatment. Based on the conducted studies, the choice of temperature conditions for the transesterification of oil in dimethyl carbonate medium was substantiated and additional information on the composition of the products was obtained.

The authors declare no conflict of interests regarding the publication of this article.

Authors Index.