Ore flotation is the main and defining technological process in ore benefication and non-ferrous metals production. The flotation process requires the use of a variety of chemical reagents, including collectors, frothers, surface modifiers, and pH regulators. The development and selection of suitable reagents for the processed material play a vital role in efficient flotation. The flotation activity of collectors depends fundamentally on the composition and structure of the hydrophobic and hydrophilic fragments forming the flotation agent molecule, as well as on the nature of the ore that undergoes flotation processing. In this regard, the identification and study of the “substance structure–flotation activity” relation, as well as the search for new effective flotation reagents gain importance within applied organic and organoelement chemistry and related branches of science and technology. In this article, we review syntheses of effective collector reagents, namely xanthates and dithiocarbamates, based on the literature data for the past five years. Where necessary, earlier sources are provided. The reaction conditions and yields of the target compounds are presented using schemes. In addition, we present the results of flotation tests on the surfaces of various ores and the data on the mechanism of concentrate extraction. According to the reviewed publications, the fixation of collector reagents on the surface of minerals can be regarded as a complexation process of the collector functional groups and metal ions located on the surface of the mineral.

The current ecological situation attracts particular attention to alternative energy sources with no detrimental impact on the ecosystem. In comparison with conventional energy sources, fuel cells exhibit the following advantages: small and compact size, light weight, lack of noise when working, and cost-effectiveness in terms of fuel consumption. Most importantly, fuel cells are environmentally friendly, since no harmful substances are released into the atmosphere during their operation. Their goal is to convert chemical energy from various sources into environmentally friendly electric power. At present, chemical sources of energy are used everywhere, including batteries for mobile phones, laptops, as well as cars and uninterruptible power supplies, to name a few. The main components of solid polymer fuel cells are proton-exchange membranes, the main function of which is to ensure the transfer of protons from the anode to the cathode. The proton conductivity of such materials is determined by the presence of hydrophilic channels that transport mobile protons. The proton-exchange membrane must meet the following requirements: electrochemical and chemical stability in aggressive chemical environments, mechanical and thermal strength, low permeability to reagent gases (fuel and oxidizer), high ion exchange capacity and electrical conductivity, as well as a relatively low cost. This paper considers perfluorinated sulfonic acid membranes, organic–inorganic and acid–base composite membranes, as well as hybrid membranes obtained by sol-gel process, which can contribute to the development of technologies related to fuel cells in the future.

Microalgae represent a large group of prokaryotic and eukaryotic, mainly photoautotrophic, single-cell or colony-forming microorganisms. These microorganisms are recognized as renewable, sustainable and economically profitable sources of biofuels and biologically active compounds for the production of drugs and food additives. Microalgae compounds, such as carbohydrates, peptides, lipids and carotenoids, attract particular attention in pharmaceutical biotechnology and medicine due to their antitumor, anti-inflammatory, antibacterial, antiviral and antioxidant properties. In addition, microalgae are suitable organisms for the production of recombinant proteins/ peptides, such as monoclonal antibodies and vaccines. In this work, we aim to review publications by domestic and foreign researchers on the pharmacological effects of biologically active microalgal compounds. The literature search was performed using the ResearchGate, PubMed, Web of Science, ScienceDirect, Scopus, Google Scholar and eLibrary databases covering the period from 2000 to 2022. The article provides information on a wide range of pharmacological effects of biologically active compounds of microalgae, which are shown to exhibit antibacterial, antiviral, antitumor, antioxidant, regenerating, hypotensive, immune-stimulating and anti-inflammatory activity. The mechanisms of the main pharmacological effects are described. The main pharmacological effect was established to be the antimicrobial action. The data presented in this review can be useful when determining promising directions for the development of drugs based on algae extracts.

This paper proposes an algorithm for searching and analyzing the structures of CRISPR-Cas systems of bacteria and screening bacteriophages through spacers in CRISPR cassettes using bioinformatic research methods in the genomes of Klebsiella pneumoniae strains. The aim was to determine and study the structure of CRISPR-Cas systems of bacteria on the example of Klebsiella pneumoniae strains using bioinformatic research methods in order to develop approaches for the selection of target bacteriophages. The research object included 150 genome-wide sequences downloaded from the GenBank database. Of these sequences, CRISPR-Cas systems were detected in 52 strains, which amounted to 34.7%. Using several search algorithms in the CRISPR-Cas systems of the studied strains, the presence of one and two CRISPR cassette was determined in 46.2 and 53.8% of cases, respectively. In all the cases, a complete set of Cas genes characteristic of Type-I Subtype-I-E systems was identified next to the cassettes. The total number of the identified spacers was 1659, of which 281 spacers were repeated in two or more CRISPR loci, while 505 spacers had no repeats. The number of spacers in the cassettes ranged from 4 to 64. The analysis of the spacer composition in CRISPR cassettes of antibiotic-resistant and hospital strains provided information on their evolutionary history and on the bacteriophages which are targeted by their CRISPR systems. The developed bioinformatic analysis algorithm enables creating a platform for the development of personalized bacteriophage therapy technologies.

Studies into photochemical oxidation can enhance the current understanding of degradation processes within aqueous solutions of active pharmaceutical ingredients (APIs). APIs are complex decomposable compounds that, once in reservoirs, cause irreversible consequences in living organisms. The results obtained on the photodestruction of various drugs in water in the presence of hydrogen peroxide and peroxydisulfate contribute to gaining new practical and theoretical knowledge in the field of water treatment, post-treatment, and purification. The paper presents laboratory results on the oxidation of model aqueous solutions of nitrofural, tetracycline, and paracetamol under the combined effect of UV radiation with micro-additives of oxidants (hydrogen peroxide and peroxydisulfate). The reaction order of APIs destruction is determined by the least square method. The results show that the combined effect of UV radiation and microadditives of hydrogen peroxide and peroxydisulfate contributes to both a high degree of purification (up to 98%) and a high rate of oxidative degradation of APIs (nitrofural, tetracycline, and paracetamol) compared to the use of UV radiation separately. The studied drugs can be arranged in the following order in terms of their oxidative degradation transformation ability: nitrofural>tetracycline>paraceta mol. The paper theoretically proves that photochemical destruction in the presence of peroxydisulfate leads to the formation of more highly reactive oxygen-containing radicals, which are involved in the decomposition of nitrofural, tetracycline, and paracetamol.

The use of sprouted seeds of cereals and legumes in human nutrition requires establishing an appropriate process of their production in the food industry. It takes one-two weeks for seeds to germinate in natural conditions, which is not viable for their industrial production and processing. In this regard, various technological techniques are being undertaken to accelerate the process of seed germination, based on the intensification of biochemical processes occurring in the seed embryos. The aim of this paper is to identify the temperature regime of germination for pea seeds at each stage of a two-stage technological process to optimize their germination over time. The research is based on the data on the temperature regime and germination time of pea seeds of Temp, Sofia, Spartak, Amior and naked barley varieties, the chemical composition of which is crucial during germination. The quantitative estimates of the maximum germination temperature of seeds are determined based on the known computational dependencies. Within the framework of a two-stage approach to the process of seed germination, the following temperature regime of their germination in technological processes is proposed: at the first stage – 37 °C; at the second stage – 30 °C. That will intensify the germination process and increase the yield of seedlings when scaling.

This paper presents the results of studying the inorganic components of sunflower stems. The test objects are the extracts obtained at different pH values of the medium and ash samples before and after treatment of stems with water, acid, and alkali. The results show that the nature of the extractant has a negligible effect on the yield of extractive substances from the crushed stems. According to atomic absorption analysis, the main ions in extracts obtained in different media are potassium, calcium, magnesium, and sodium ions. The mass fraction of ash after treatment of stems with solutions at different pH values varies from 0.5 to 5.2%. The lowest ash yield is characterized by a sample of stems after acid extraction. According to energy dispersive X-ray fluorescence spectroscopy, all ash samples contain mainly K, Ca, Mg, and P compounds. The ash components of the core and outer part of the stem were also studied in comparison with the original sample. The ash content of the stem core (9.3%) is higher than that of the outer shell (7.4%). The IR spectroscopy shows that the nature of band splitting in the IR spectra of the ash samples practically does not depend on the stem part and the pretreatment of raw materials at different pH values. Absorption bands characteristic of carbonates and silicates are observed in the IR spectra of the stem ash. According to X-ray diffraction analysis, the studied ash samples are in a crystalline state.

Thyme (Thymus vulgaris L.) has been used for centuries in traditional medicine due to its various health benefits, and it is widely used today in aromatherapy, cosmetics, and even as a culinary herb. This study aimed to investigate how the chemical compositions and antimicrobial activity of essential oils extracted from the aerial parts of T. vulgaris were affected by storage at different temperatures. The essential oils were obtained by hydrodistillation of air-dried samples and analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The study observed changes in the essential oil’s composition when stored in a refrigerator (4 °C) and at room temperature (25 °C) for three months. The results revealed that the proportions of compounds with lower boiling temperatures such as β-myrcene (2.29–0.20%) and α-pinene (2.74–0.24%) along with γ-terpinene (7.84–4.81%) and p-cymene (10.93–5.61%) as thymol and carvacrol precursors, were significantly decreased when stored at room temperature. However, the amounts of thymol and carvacrol increased by 51.64 and 21.81%, respectively, after three months storage period, indicating a rise in the oil quality index. Storing the essential oil in a refrigerator resulted in minimal changes to the essential oil composition and maintained its primary quality. In addition, the antimicrobial activity of the essential oils was tested using the broth microdilution method and demonstrated that the essential oils from both storage methods retained their antimicrobial activity compared to freshly extracted ones. In summary, these findings are beneficial for essential oil producers and consumers in the pharmaceutical and cosmetic industries.

Apple tree is the most common among other fruit crops. Apple fruit is the primary raw material used in cider making. Although the majority of Russian regions are rich in raw materials for the production of high-quality cider, the development of this industry is hampered by a number of issues. As a result, the domestic market sometimes offers low-quality and adulterated products. In this work, we study the organoleptic and biochemical indicators (volatile components, metal cations, phenolcarboxylic acids and organic acids) of fermented diffused apple juice and ciders prepared from both freshly squeezed and reconstituted apple juice. The biochemical composition and organoleptic characteristics of samples were determined by conventional methods, such as high-performance liquid chromatography (organic acids), capillary electrophoresis (phenolcarboxylic acids) and gas chromatography (volatile components). The concentrations of most of the studied parameters and organoleptic indicators werehigher in ciders from fresh apple juice. However, in the fermented diffused juice, the concentrations of chlorogenic (9.5 g/dm³), orotic (1.9 g/dm³) and gallic (4.7 mg/dm³) acids, as well as furfural (11.84 mg/dm³), exceeded those in other studied samples. Future research should investigate the possibility of secondary use of apple pomace, e.g., for the production of fruit spirits. Involvement of such raw materials ensures the rational use of secondary raw materials.

This work investigates the growth and productivity characteristics of such lactic-acid producing strains, as Lactobacillus delbrueckii subsp. bulgaricus 19-11 (VKPM B-2368), Lactobacillus acidophilus 5 Ds (VKPM B-2846) and Lactococcus lactis subsp. lactis (VKM B-1662) on standard MRS medium using glucose syrup as a carbon substrate. According to the results of batch cultivation of the selected strains in 5L fermenters for 72 h, the productivity was established to decrease in the Lactobacillus delbrueckii subsp. bulgaricus 19-11 > Lactobacillus acidophilus 5 Ds > Lactococcus lactis subsp. lactis series. L. delbrueckii subsp. bulgaricus 19-11 showed the maximum lactic-acid productivity of 1.94 g/(l×h) with a glucose conversion degree of 87%. After cultivation, a slight decrease in the content of nitrogen, potassium and sodium in the culture liquid of the studied strains was observed. In all strains, the content of other macronutrients (phosphorus, calcium, sulphur, magnesium, barium and iron) increased in proportion to the addition of glucose syrup during cultivation, which is directly related to their significant content in its composition. The Lactobacillus delbrueckii subsp. bulgaricus 19-11 and Lactobacillus acidophilus 5 Ds strains produced racemic (DL) lactic acid, whereas Lactococcus lactis subsp. lactis produced lactic acid with a 73% L-isomer content. The use of glucose syrup in biotechnological processes can contribute to the implementation of waste-free production in the respective enterprises.

The study of variability in the chemical composition of fruits under the influence of external factors is important both in terms of adaptation processes of fruit plants and for practical purposes. In this research, we aimed to carry out a comparative analysis of the biochemical composition of apples of such zoned varieties, as Ekrannoe (autumn ripening), Blagaya Vest’ and Krasa Sverdlovska (winter ripening). The trees were growing in different agrocenoses: in a horticultural research station (conventional extensive cultivation) and in a farm (intensive cultivation). For all the studied apple varieties, the content of insoluble nutrients (1.4–1.6 g/100 g), as well as the level of flavonoids (0.4%) and titratable acidity (1.5–1.7%) for winter fruits, were characterized by the lowest variability among other indicators. These indicators, therefore, can be considered species-specific. The level of polyphenols and antioxidant activity of winter apples can be considered variety-specific indicators for Blagaya Vest’ (0.52–0.53 mmol/l gallic acid equivalent; 71.2–75.9%) and Krasa Sverdlovska (0.65 mmol/l gallic acid equivalent; 89.7–90.1%), respectively. In all apple varieties, the contents of organic acids, vitamin C, dry matter, sugars and mineral elements showed the greatest dependence on growing conditions. In winter varieties, this list also included the sugar/acid ratio. In terms of biochemical composition, autumn-ripening apples proved to be more responsive to changes in external environmental factors.

This work sets out to investigate a green-synthesized biopreparation produced by introducing iron or copper nanoparticles into a microbial liquid-phase biological product (LBP). The obtained nanoparticles were analyzed by diffuse reflectance IR spectroscopy and introduced into the LPB at the stage of its ripening in the LPB:particle solution volume ratio of 50:1. As a result, two new biopreparations – LPB-Fe and LPB-Cu – were obtained. All LPB samples, as well as iron and copper nanoparticles, underwent laboratory testing on flax seeds of Tverskaya variety. Iron or copper nanoparticles in the composition of biological preparations were found to affect positively the process of seed germination. In the LPB-Fe variant, seed germination ranged between 86–91%, which exceeded that in the control by 3–12%. In the LPB-Cu variant, seed germination ranged between 86–93%, which exceeded that in the control by 3–11%. However, in the latter variant, the maximum average length per seedling was 14.5–14.8 cm. The average length per seedling was significantly affected by watering the seeds with a solution containing only iron nanoparticles, with the maximum value of this parameter reaching 16.1±1.2 cm. According to the results obtained, this research direction has good prospects and requires additional experiments by varying the nanoparticle concentration in LBPs.

Assessment of the distribution of nutrients and pollutants in the soil-plant system is a relevant theoretical and applied task in biogeochemistry, agrochemistry and environmental biotechnology. Pointwise, average and extreme values of the concentration of the studied substance in the plant (C_p) and in the soil (C_s), as well as biological absorption coefficients (K_ab=C_p /C_s), do not characterize the distribution of the studied substance in the system. This work investigates the effect of substance concentration in a soil on its distribution between the plant and the soil. The use of the C_p=f(C_s) and K_ab=f(C_s) functions for describing the substance content in the plant depending on its concentration in the soil, allowed us to propose approaches to quantitative assessment of the distribution process. The first approach consists in the approximation of dependences by Freundlich and Langmuir linear or adsorption power functions C_p=f(C_s), on which basis the concentration parameters of а, ¹К_р, К_р, С_∞ are determined. These parameters are used to study the mechanism and intensity of substance accumulation by a plant. The second approach includes obtaining a power function Kab=f(C_s) or its linear representation lgK_ab=f(lgC_s) and calculating standardized coefficients K_ab. These coefficients are sensitive at low (1, 10) and limiting at high (100, 1000) concentrations of the studied substance in the soil. The example of benz(a)pyrene, fluorine and zinc, i.e., substances different in terms of their physical, chemical and biological properties, was applied to demonstrate the process of determining the absolute and relative accumulation of the substances by different crop species. A comparison of different plants was conducted; possible mechanisms of the distribution of the studied substances and their intensity are considered.

Sodium percarbonate (SPC) is used as an environmentally friendly bleaching agent in synthetic detergents. This strong oxidizing agent is incompatible with some other detergent components, such as enzymes. This problem can be solved by encapsulating SPC, whose delayed release will allow the enzymes to function with maximum efficiency before deactivation in the presence of SPC. Therefore, the selection of a coating material and the coating layer thickness seems to be a relevant research direction. In this work, SPC granules were encapsulated by spraying a sodium silicate solution through a pneumatic nozzle over a fluidized layer of granules. Encapsulated SPC samples with the coating content of 5, 8, 10 and 13% of the mass of the initial product were obtained. The dissolution kinetics of the obtained capsules under static and dynamic conditions was studied. At the relative coating mass of 5, 8, 10 and 13%, the dissolution time under dynamic conditions comprised 10, 14, 19 and 30 min, respectively. In order to predict the release of the active component from encapsulated SPC under the conditions different from those used in the conducted experiments, a mathematical model of this process was obtained. For parametric identification of the mathematical model by solving an inverse problem, the value of the effective diffusion coefficient of SPC through the capsule was found to be 1·10-10 m²/s. The calculated and experimental values of SPC release from the encapsulated granules showed good agreement.

A calcined sorbent from ash and slag waste of thermal power plants was used for water purification from ammonium ions. Experiments were carried out under static conditions at a temperature of 25±2 °С. The concentration of ammonium ions in the solution was measured by the spectrophotometric method according to the established graduation characteristic tested for convergence and correctness. The sorption process was studied at a sorbent dose of 1.0 g per 50 cm³ of the model solution taking the specific pore volume of the sorbent into account. For a solution with an ammonium ion content of 20 mg/dm3, the following modifications were carried out: the frequency of magnetic stirrer rotation was varied from 50 to 500 rpm; the pH of the solution – from 4 to 9; and the time to equilibrium – from 10 to 210 min. The time to equilibrium was 180 min. The effect of initial concentration of ammonium ions (2.0; 5.0; 20; 50 and 100 mg/dm³) in the solution on the adsorption process was studied under optimal sorption parameters. The adsorption equilibrium in the “ammonium ions–calcined sorbent” system was studied for the initial concentration of ammonium ions from 5 to 300 mg/dm³. Experimental data were processed using Langmuir and Freundlich adsorption isotherms. The maximum value of adsorption comprised 1.1251 mg/g. The experimental data were found to agree with the Langmuir theory. To describe the adsorption kinetics, the parameters of pseudo-first and pseudo-second order equations were determined. The highest convergence between the experimental and calculated data was achieved by the pseudo-first order model.

The development of novel membrane materials for hydrogen fuel cells, a promising environmentally friendly technology, represents a relevant research task. In this work, we propose an approach to creating proton-conducting membranes from an industrial polyethylene terephthalate (PET) dielectric track-etched film. An N, P-containing ionic liquid was used as a modifying agent, whose polymerization was carried out directly in the PET membrane pores. The ionic liquid was obtained using a novel approach to the directed synthesis of organophosphorus compounds from elemental phosphorus via the Trofimov-Gusarova reaction developed at the A.E. Favorsky Institute of Chemistry of the Siberian Branch of the Russian Academy of Sciences. The ionic liquid properties were characterized by NMR and IR spectroscopy. The application of the obtained N, P-containing ionic liquid onto a PET membrane was shown to yield a material exhibiting the required mechanical parameters for operation as proton-conducting membranes. The novel proton-conducting materials demonstrate a high proton conductivity of 77.76 mS·cm-1 at 353 K. The obtained proton-conducting membranes seem promising for application in hydrogen fuel cells, thus contributing to the development of effective alternative energy sources.

The use of cellulose-containing plant materials for obtaining bioproducts comprises a relevant research direction in the field of sustainable economic development. Herbaceous cellulose-containing raw materials are among the most widespread and easily renewable resources. In this study, we set out to identify herbaceous cellulose-containing raw materials suitable for biotechnological processing among the following plants: cane, miscanthus (Soranovsky variety), water hyacinth, iceberg lettuce, Sudan grass, oat husk, flax straw (Linum usitatissimum L.). Preliminary chemical treatment of raw materials was carried out by the conventional method of alkaline delignification at atmospheric pressure. The obtained substrates were converted into a solution of reducing sugars by enzymatic hydrolysis. The method of alkaline delignification of initial raw materials was found to be suitable for obtaining products with the cellulose mass content of 82.9–93.1% by the Kurschner method. This conversion rate can be considered a good indicator for further enzymatic hydrolysis. According to the results of enzymatic

hydrolysis of alkaline delignification products, the highest reactivity to enzymatic hydrolysis was demonstrated by the alkaline delignification products of miscanthus (Soranovsky variety), iceberg lettuce and oat husk. For these plants, the concentration of reducing substances reached 25.0, 28.4 and 26.9 g/l, under the yield of reducing substances from the substrate mass of 75.0, 85.2 and 80.7%, respectively. Therefore, the high reactivity of these plant materials makes them prospective candidates for further biotechnological processing. Other investigated plant materials require optimization of the alkaline delignification stage to increase their reactivity to enzymatic hydrolysis.