CHEMICAL SCIENCES
The synthesis and spectral characterisation of 2-pyridylisothiuronium chloride were performed by regulating the rate of feeding 2-chloropyridine into a thiourea solution in ethyl alcohol for ensuring its low concentration in the reaction zone. According to the data of NMR spectroscopy (1H,13С,15N), the obtained compound represents an approximately equimolar mixture of two tautomers: the expected isothiuronium salt and pyridinium chloride with an isothiocarbamide substituting group in the 2nd position. The ability of isothiuronium salt to transit tautomerically to pyridinium salt is determined by the presence of two main centres, including nitrogen atoms of the isothiourea unit and a nitrogen atom of the pyridine ring. A quantum chemical analysis performed using the DFT method showed that the free energy values of the tautomers were similar, with the tautomer protonated on the nitrogen imido-atom being 2.9 (in the gas phase) and 4.7 kcal/mole (taking into account the dimethyl sulphoxide solvent DMSO at the PCM level) more advantageous as compared to the pyridinium salt. A small difference in the tautomer energies determines their formation in an approximately equimolar quantity. A rapid addition (5–10 mL/min) of 2-chloropyridine to the thiourea solution in the reaction zone creates the surplus of the reagent, acting as a base and causing splitting of the isotiuronium salt. This leads to an additional formation of bis(2-pyridyl)sulphide in the reaction medium, representing a valuable ligand for obtaining coordination compounds. The synthesised mixture of tautomers was examined as an additive to the standard nickel-plating electrolyte. In the concentration of 0.3–0.5 g/L, this additive ensured the production of bright low-porous nickel coatings at a sufficiently high current density of 5–10 A/dm2 and a current yield of 98–99 %.
At present, industrial and agricultural waste is often used as sorption materials for water remediation. Adsorbents obtained from sunflower husks were used for wastewater treatment from chromium (VI) ions. Studies were carried out using unmodified and modified sunflower husk and a model wastewater solution containing 10 mg/dm3 of chromium (VI) ions. Solutions of acids (H2SO4, HNO3, HCl, H3PO4) and alkalis (KOH, NaOH) were used to modify sunflower husks. The maximum sorption capacity was revealed in sunflower husks treated with sulfuric acid; thus, this modifying agent only was used in further experiments. The modification was carried out using 1–4 M solutions of H2SO4 at 30–75 °C for 30–120 min. The research results showed that the acid treatment of sunflower husks is more effective than that using alkalis. The sorption capacity of the modified sunflower husk increased up to the concentration of sulfuric acid of 3 M, followed by a further decrease. A full factorial design having 3 factors of the experiment was set, which allowed the maximum sorption capacity to be identified. The optimal modification procedure was as follows: sunflower husks are treated using 2.5 M sulfuric acid solution at 60 °C for 30 min, washed with distilled water and dried at 105 °C to a constant weight. Studies showed that adsorbents obtained from sunflower husks can be used to remove chromium (VI) ions from wastewater.
This work addressed the directed synthesis of a new phase Rb5Li1/3Zr5/3(MoO4)6, along with the determination of its crystallographic, thermal and electrophysical properties. The directed synthesis of the Rb5Li1/3Zr5/3(MoO4)6 phase was carried out using the solid-state reaction in the temperature range of 350–470 °C. According to differential scanning calorimetry, the synthesised compound Rb5Li1/3Zr5/3(MoO4)6, crystallised in trigonal form (space group R3c, Z = 6), undergoes a diffused first-order phase transition. The structure of triple molybdate Rb5Li1/3Zr5/3(MoO4)6 comprises MoO4 tetrahedra and octahedrally coordinated MO6-polyhedra. This structure is characterised by a statistical distribution of lithium and zirconium atoms in the M position (M1 = 0.790 Zr + 0.210 Li, M2 = 0.877 Zr + 0.123 Li). Rb atoms are located in the large voids of the tetrahedronoctahedral framework. The electrophysical properties of triple molybdate Rb5Li1/3Zr5/3(MoO4)6 having a scaffold structure favourable for ion transport, were studied. The correlation between dielectric and thermal characteristics in the high-temperature region near the phase transition was revealed. The temperature and frequency dependences of electrical conductivity were measured at 473–873 K in heating and cooling modes in the frequency range of 1–10 kHz. The compound exhibited a high thermally activated conductivity, reaching 1.48·10-2 Cm K/cm with activation energy in the range of 0.6–0.8 eV at a temperature of 480 °C. Well-shaped semicircles in the low-frequency region and unresolved arcs in the high-frequency region changing with increasing temperature were observed in the impedance spectra of ceramic Rb5Li1/3Zr5/3(MoO4)6 sample at various temperatures. The evolution of the imaginary part (Z'') as a function of the real part (Z') of the complex impedance resembled that of the complex impedance for compounds having ionic conductivity.
PHYSICOCHEMICAL BIOLOGY
Industrial development has led to immense emission and accumulation of hydrophobic organic compounds (HOC) in the environment. Primarily, they include petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The extensive use of hydrophobic pesticides in agriculture led to the contamination of soil, air and water. Many of the hydrophobic substances are dangerous for the biota due to their high toxicity and carcinogenic and mutagenic activity. In addition to their widespread use, the possible adverse effects are also determined by their resistance to decomposition, including the biological one, which defines their long-term persistence in soil, water and other media. The impact of HOC on ecosystems poses a potential threat not only to the environment but also to human health. Numerous studies were devoted to the remediation of soils polluted with HOC. The approaches to remediation can be conditionally divided into mechanical, chemical and bio-methods, with the former two being widely used in the past. Bioremediation methods proved more efficient and, as a rule, more cost-effective and environmentally friendly. In recent years, the good efficiency of solubilizing agents in bioremediation processes has been demonstrated. Various surfactants have become widely popular due to their ability to increase desorption, water solubility and microbial bioavailability of HOC. In this brief review, state-of-the-art literature data on the biodegradation of hydrophobic organic compounds using surfactants were considered.
The aim of this research is to determine the effect of Althaea rosea flower gum loaded with Thymbra spicata essential oils coating on packaged beef patties during cold storage. For this purpose, samples were evaluated in terms of pH, color, thiobarbituric acid reactive substances (TBARS), and microbiological properties. In addition, texture profile analysis (TPA) was performed to evaluate the textural properties of the beef patties. The essential oil treatment to the beef patties had a significant effect (p<0.05) on the pH values at the end of storage. The coating significantly affected the L* (lightness), a* (redness) and b* (yellowness) values (p<0.05). A similar situation was also found for lipid oxidation (1.00 µmol MDA (g). The coated samples with essential oil-treated had the lowest values of total aerobic bacteria (3.29 log CFU/g), yeast and mold (2.99 log CFU/g), lactic acid bacteria (2.23 log CFU/g), and total psychrophilic bacteria (2.58 log CFU/g). While the effect of the coating on the adhesiveness, gumminess, and chewiness values of the beef patties at the end of storage was significant (p<0.05), it did not affect other textural properties. Current research has shown that Althaea rosea flower gum can be used in edible coatings and, when fortified with Thymbra spicata essential oil, can be used in muscle foods for preservation and shelf-life extension.
Silk sericin comprises a globular water-soluble protein that surrounds silk fibres, sticking them together and providing cocoon adhesion. Sericin was isolated from the extract solution in two ways: the first sample was obtained by concentrating the filtered extract at low pressure (SLP); the second sample was obtained by ultrafiltration (SUF) using a membrane. In this work, the size exclusion-high-performance liquid chromatography involving viscometry and refractive index detectors was used to determine the molecular weight and conformation of sericin polypeptides obtained from cocoons of the Bombyx mori silkworm. The aggregation processes of silk sericin protein under various isolation conditions from the solution were considered. It was shown that sericin macromolecules are present as a monodisperse polypeptide at low concentrations, which aggregates at concentrations greater than 1–2 mg/ml. The obtained data indicate that, along with the parameters of the extraction process, the conditions for its isolation from the solution, including temperature, pressure and degree of concentration, affect the molecular weight and aggregative behaviour of the protein. The results confirm and complement previously obtained data on the influence of various factors on the association of protein macromolecules in solution. The resulting sericin fractions can find many applications, including materials for tissue engineering, coatings for surface modification, cell culture media, cosmetics, as well as food additives and medical biomaterials.
Although the entomopathogenic bacteria Bacillus thuringiensis Berliner are well-known bio-agents for regulating the population of leaf-eating pests of agricultural and ornamental crops, other agricultural properties of this microorganism are promising. In this work, the growth-stimulating effect of entomopathogenic strains of B. thuringiensis on Deviz pea plants was studied. The entomopathogenic strains B. thuringiensis 685, 926 and 109-C obtained from the Crimean Collection of Microorganisms of the Crimean Agricultural Research Institute, registered online (http://www.ckp-rf.ru) with number 507484, were used as research material. The morphometric parameters of pea sprouts were evaluated following standard methods. Biochemical parameters of pea sprouts were determined for 10-day-old sprouts. The amylase activity of pea sprouts was determined by photocalorimetry; total acidity was measured by titration using 0.1 n NaOH solution; total water-soluble phenolic compounds were determined by Leventhal titrimetric method. It was found that liquid spore culture of strains B. thuringiensis 685, 926 and 109-C had a stimulating effect on the length of root and stem and the weight of 10-day-old sprouts of Deviz pea variety. Treatment with a spore suspension of all tested strains B. thuringiensis led to an increase in the content of organic acids in the sprouts by an average of 12.4% compared with that of the control. Maximum stimulating effect on amylolytic activity and synthesis of phenolic compounds in Deviz pea sprouts was achieved by treating with a spore suspension of the strain B. thuringiensis 926. The amylase activity increased on average by 41.5% when compared to that of the control, while the total content of phenolic compounds in this experiment was 2.3 times higher than that of the control. Therefore, in light of the entomopathogenic properties and the obtained data on the growth-stimulating activity of the strains of B. thuringiensis, it can be concluded that these bacteria have additional potential for their use in agriculture as a bio-agent for plant protection having a complex action.
Since late 2014, following the embargo, a significant reduction in cheese import, including mould cheese, has been observed. Developing new cheese technologies comprise therefore an urgent task for the milk industry. The cheeses ripened using noble mould represent a wholesome product, rich in protein, which contains many essential amino acids, beneficial for strengthening the walls of blood vessels and reducing angiasthenia. The microorganisms in the cheese starter culture create favourable conditions for healthy microflora in the gastrointestinal tract, preventing fermentation and meteorism. The high content of vitamin B12 in these cheeses has a positive effect on the central nervous system. Any production must be economically viable, lowering the production costs. In order to increase income, and consequently the profitability of production, the method of cheese ripening using a noble mould, obtained from a mixture of whole milk and secondary protein-carbohydrate raw materials, was proposed. The influence of the type of protein-carbohydrate raw material, yeast and mould on the physicochemical and organoleptic properties of the product was investigated. The optimal ratio of raw materials (milk:buttermilk) for cheese production was determined. The relative composition of nitrogen fractions and the presence and amount of volatile fatty acids in the proposed product were also examined. It was shown that proteolysis and lipolysis processes were more intensive in the experimental cheeses produced using a noble mould, resulting in the improvement of organoleptic characteristics of the finished product. The resulting soft cheese having unique characteristics and a tangy mushroom flavour can be recommended for production in cheese factories.
At present, hemp seeds are becoming increasingly popular as a source of nutrients. This work addressed the dynamics of macronutrients in the process of short-term germination of hempseeds by chemical and spectroscopic methods. Lyudmila 2021 cultivated hemp seeds along with hemp sprouts were used as objects of research. The germination of hemp seeds was carried out under laboratory conditions using special trays at 18–20 °C with the water added at a ratio of 2:1 for 5 days with periodic moistening. The obtained experimental data on the protein complex suggested that, in the studied interval of the germination of hemp seeds, the key hydrolytic decomposition of proteins occurs along with changes in structural components, including through the synthesis of new proteins accompanying the sprouting. The variations in such parameters as fat content, acid number and peak intensity of functional groups in the lipid fingerprint region (1745, 1157 and 1140 cm-1) indicated the accumulation of fatty acids as a result of the hydrolysis of triglycerides. The analysis of the IR spectra of hemp sprouts and the intensity of the bands of the corresponding functional groups in the carbohydrate region (1200–680 cm-1) suggested the intensive hydrolytic decomposition of polysaccharides. The variation in the content of extractive matter in the aqueous solutions of hemp sprouts indicated the accumulation and utilisation of water-soluble substances at the early stages of germination. The data on the predominance of water- and salt-soluble protein fractions indicated an increase in the biological value of hemp seeds during short-term germination.
This article examines the distribution of nitrogen-transforming bacteria in an artificial reservoir (pond) populated with aquatic higher plants of common reed (Phragmites australis) and cattail (Typha) for treating swine wastewater. In the pond occupied by Phragmites australis, 7 strains of ammonium oxidising and 14 denitrifying bacteria were identified, while, in the pond occupied by Typha, 6 strains of ammonium oxidising and 19 denitrifying bacteria were distinguished. A comparative analysis of bacterial count at various sampling points revealed their decrease along the artificial pond. Most of the bacteria strains oxidising ammonium were identified in the samples collected from the surface layer of the pond, while denitrifying bacteria dominated the bottom layer. The isolated microorganisms identified by 16S rRNA sequencing belonged to the genus Pantoea, Enterobacter and Bacillus. An artificial pond having aquatic higher plants is characterised by a diverse microbiota, whose composition strongly depends on the wastewater source rather than on the cultivated plant species. The ammonia transformation and denitrification capacity of isolated bacterial strains was determined. The highest conversion efficiency of ammonia (up to 56%) was observed for Enterobacter cloacae bacteria isolated from the surface layer of the pond. Denitrifying bacteria sampled from the bottom layer allowed for the reduction in nitrate content from 20 to 10 mg/L in 72 h. The obtained results confirm the role of bacteria in the treatment of wastewater against nitrogen-containing pollutants, with the average efficiency of removal of inorganic nitrogen compounds being 50%.
In this paper, a hypothetical method for locating SNPs (single nucleotide polymorphisms) on the example of the ribonuclease gene WIN was proposed. Ribonuclease comprises an enzyme that participates in defence reactions against fungal infections in soybeans, as well as other protective responses to biotic stress. Its belonging to the RNA-ases group determines the specific properties, namely the ability to degrade foreign nucleic acids. This ability provides for a general nonspecific immune response of the plant to the invasion of antigenic structures. Modern biotechnology calls for the development of molecular methods and approaches that will increase the resistance of a culture or accelerate the processes of its adaptation in the field. This problem can be solved by using technologies of SNP artificial induction in those parts of the genome that encode proteins capable of acting in protective reactions against biotic stress. In the study, 5 single-nucleotide polymorphisms were proposed using bioinformatic analysis. Since the localisation and detection of SNPs comprise a challenging task due to the presence of a single nucleotide change, in the biotechnological practice, predictive analysis is carried out in order to localise the potential sequence of occurring single-nucleotide polymorphism. Following the identification of the hypothetical SNP location, they can be further detected using complex molecular methods, such as real-time PCR or local sequencing. This technology can become a powerful tool for breeding soybean varieties having predetermined properties. Such theoretical and predictive models will allow for a quicker response to the dynamic environment under manmade load on plants.
In recent years, the popularity of dietary supplements based on pine pollen has significantly increased due to over a thousand years of its use in Chinese traditional medicine and diverse biological activity. Microstrobili are harvested prior to flowering in order to obtain pine pollen, and, following its separation, waste comprising empty microstrobili in the amount of 90–95% of the mass of raw material is formed. In this work, the elemental composition of Pinus sylvestris, P. sibirica and P. pumila microstrobili obtained following the separation of pollen (empty microstrobili (EM) was determined and compared with pharmacopoeial raw material, i.e., P. sylvestris sprouts. The elemental composition was analysed using atomic absorption spectroscopy with preliminary acid mineralisation in a microwave system. A comparative analysis of the elemental composition showed that EM contains a significant amount of K (8710–10187 mg/kg), Mg (627–1079 mg/kg), Mn (129–179 mg/kg), as well as Zn (37–67 mg/kg) and Cu (7.4–10.3 mg/kg). The series of accumulation of chemical elements was identical for microstrobili and sprouts of the studied pine species (K>Mg>Ca>Mn>Fe~Zn>Na>Cu>Ni~Cr>Co>Pb>Cd>Hg). EM can be used to enrich the diet with macroand microelements such as K, Mg, Mn, Fe, Zn and Cu. The content of toxic Cd, Pb and Hg was below the maximum permissible standards for medicinal plant raw materials and dietary supplements thereof. Obtained for the first time, data on the elemental composition of EM of P. sylvestris, P. sibirica, P. pumila and sprouts of P. sibirica and P. pumila can be used for further sanitary measurements of a new type of raw material.
CHEMICAL TECHNOLOGY
The work investigates the influence of the physicochemical properties of depressor additives on their performance in diesel fuels of various chemical and fractional compositions. Heavy, summer and marine diesel fuels were used. The following physicochemical properties of fuels were determined: cloud point, freezing point, density, viscosity, fraction composition and hydrocarbon content that formed a complex with carbamide. The content and molar mass distribution of individual n-alkanes in diesel fuels were determined. The following foreign depressant-dispersing additives were used: Dodiflow with codes 4971, 5416, 5817 and 7118, Keroflux with codes 3501, 5696a and Ofi-8863. Their active agents were isolated from the commercial additives by dialysis using semi-permeable rubber membranes. The dropping point of the active agents, their intrinsic viscosity in kerosene and the refractive index at 100 °C were identified. The content of vinyl acetate components and the degree of branching of aliphatic radicals of depressor additives were determined using infrared spectroscopy of the active agents. The relationship between the physicochemical properties of depressor-dispersing additives and their performance in diesel fuels was established. Additives characterised by a relatively high melting point, an average intrinsic viscosity and low branching of aliphatic compounds in the polymer structure exhibit the best performance in fuels. The consumption of additives to achieve the maximum depression of freezing point decreases with the transition from summer to marine fuel and further to heavy diesel fuel. A complex tкп / СВА value, comprising the ratio of the dropping points tкп and the content of vinyl acetate components in the additives, was proposed as a means of predicting the efficiency of depressant additives СВА. In the range of tкп / СВА values of 3.02–4.00 the additives have universal depressant properties. A correlation was established between the refractive index nD100 of additives and the complex value tкп / СВА (R2 = 0.975).
BRIEF COMMUNICATION
It is known that the highest content of auxins is found primarily in the areas of active mitosis, including young leaves, apical meristems, cambium, embryos and endosperm, as well as developing fruits, which determines, among other things, plant habitus and fruit size. In agriculture and biotechnology, auxins (indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) are used to stimulate lateral development, including in apple tree rootstocks. Despite the crucial role of endogenous IBA in rooting, its presence in apple tree tissues remains unconfirmed, although its content in planta was shown for many other plants. Therefore, in this work, the composition and content of auxins in 2 tissue types of Siberian apple tree of lowand high-growing forms, along with the presence of IBA in them, was compared. Tissues of ovary and bark of Siberian apple tree (Malus baccata L. Borkh.) of 2 forms (low and tall) growing on an experimental plot of Siberian Institute of Plant Physiology and Biochemistry SB RAS were used in the study. Bark samples were collected from the 1st year shoots at the stage of intensive sap flow. The ovary samples were collected in July at the stage of active growth. Auxins purified by solid-phase extraction were analysed by GC-MS. In addition to IAA-3, the following auxins were found in fast-growing tissues of the Siberian apple tree both in the cambium layer of annual gain during intensive sap flow and set fruit during the active growth stage: IBA, indole-1-acetic acid, indole-3-carboxylic acid and indole-3-propionic acid. Similar to other plants, the content of these auxins was significantly lower than that of endogenous IAA.
Since 2020, surface disinfection has become particularly relevant thus requiring improved approaches to its implementation. Conventional disinfectants comprising concentrated solutions or soluble tablets fail to fully comply with the need for antimicrobial protection of surfaces, calling for their repetitive application. This leads to considerable expenses, with the price of disinfectants rising by 30–50% over the past two years. In this article, agents characterised by prolonged action due to film-forming antimicrobial components having good adhesion to various surfaces are developed in order to reduce the cost of the disinfection procedure and increase its efficiency. In addition, such systems can be used as additives to water paint coatings for minor maintenance of medical and preventive institutions. These materials can significantly reduce the growth rate of the harmful bacteria population, as well as provide long-term protection against it. In order to implement this approach, the polymer-polymer composition based on polyvinyl alcohol and polyhexamethylene guanidine hydrochloride was developed. It should be noted that guanidine-containing polymers are characterised by high antimicrobial activity and low human toxicity, being also widely used as active agents in disinfectants. An excellent film-forming polymer exhibiting good adhesive properties, polyvinyl alcohol is non-toxic and chemically inert. Thus, the use of such additives can significantly reduce the extension of harmful bacteria, especially in crowded public areas.
This paper addresses the possibility of modifying the Holofiber® nonwoven fabrics with a 0.05% solution of chlorhexidine bigluconate in order to impart antimicrobial properties, since these materials are planned for medical use, in particular wound dressings. One stage in the development of a wound dressing based on nonwoven Holofiber® involved its impregnation with chlorhexidine by spraying a solution using a spray gun; the solution accumulated on the surface of the nonwoven fabrics in the form of drops. The agent was applied on both sides of samples having dimensions of 210×297 mm. Samples following impregnation were dried to a constant weight. The drying time of Holofiber® VOLUMETRIC P 84 amounted to 10 min. The antibacterial properties of modified nonwoven fabrics were evaluated by the following methods: modified disc diffusion (DDM) method, measurement of antibacterial activity on the surface of plastics and other non-porous materials, ISO-22196. The inhibition zone of Staphylococcus aureus bacteria for Holofiber® nonwoven fabrics treated with 0.05% chlorhexidine bigluconate solution amounted to 17 mm, which indicates the bactericidal properties of the studied material. In addition, it was confirmed by a decrease in the number of bacteria following the 24-hour incubation of a test microorganism in the presence of a polymer. The percentage of Staphylococcus aureus cell death equalled 99%. These results indicate that the nonwoven Holofiber® fabrics can be treated with a solution of chlorhexidine bigluconate 0.05% to impart antibacterial properties, since the substance used for treating a sample remains in the material following drying and exhibits an antibacterial effect.
ISSN 2500-1558 (Online)