The effects of phytoncides contained in the juices and essential oils of various plants (garlic, ginger, onion, lemon, and pine needles) on the growth and development of pathogenic microorganisms present in classroom air during the autumn–winter period were studied. For this purpose, the growth inhibition zones and the numbers of microbial colonies grown on meat–peptone agar, a nutrient medium, were recorded over 1–7 days. After one day, the microbial growth inhibition zones in the presence of lemon juice (essential oil) and the juices (essential oils) of the other plants were 1.05 (1.25) and 1.75 (2.25) times larger, respectively, than those observed in the absence of the substances studied. Throughout the experiment, the phytoncidal activity of the plant essential oils, assessed from the microbial growth inhibition zones, was slightly higher than that of the juices of the same plants. This was apparently because essential oils evaporate much more slowly than juices owing to a combination of their chemical properties, localization in plants, and higher molecular weights. Pine needles exhibited the highest phytoncidal activity throughout the experiment and sharply slowed the increase in the number of microbial colonies. By the end of the experiment, the number of pathogen colonies formed in the presence of pine needles was 2.5 times lower than that in the blank experiment without phytoncides. The results may find practical applications in medicine in the development of air purification methods for preventing infections, particularly in operating rooms and hospital wards; in the food industry; in water disinfection; and in pharmaceutical manufacturing to ensure product safety and prevent spoilage.
This article analyzes emissions of atmospheric pollutants from stationary sources in the Siberian Federal District. The results showed that SO2, CO, C and volatile organic compounds, particulate matter, and NO are the priority air pollutants in most cities of the Siberian Federal District. The data indicate sharp increases in emissions of carbon monoxide, hydrocarbons, including volatile organic compounds, and nitrogen monoxide. From 2004 to 2024, these emissions increased by 24, 90, and 32
This article is devoted to the development and study of new-generation domestic nonwoven materials with multifunctional protective properties. The relevance of this work is determined by the need for effective import substitution and the creation of environmentally safe technical fabrics with fire-, heat-, and bioprotective characteristics. Innovative halogen-free flame retardants of the Tezagran and Termotex series based on nitrogen-containing phosphonic acid derivatives are presented. Their action is based on the phosphorus–nitrogen synergistic effect, which ensures the formation of a strong carbonized layer and a significant reduction in the release of toxic products (CO and HCN) during pyrolysis compared with foreign analogues. The results of a comparative analysis of the fire-safety and biological-resistance parameters of materials based on natural (flax and hemp) and synthetic (preox and aramid) fibers are presented. It was experimentally demonstrated that the developed formulations provide high oxygen index values (above 35
The reaction of 2,2,4,11,11,13-hexamethyl-1,5,10,14-tetraazacyclooctadeca-4,13-diene with carboxylic acid chlorides afforded N- and C-acyl substituted 2,3,6,7,8,9-hexahydro-1H-1,5-diazonines, which in solutions of deuterated solvents (CDCl3, CD3OD, DMSO-d6) exhibit an increased tendency to prototropic rearrangements. It was shown that N- and C-acyldiazonines exist in different tautomeric forms: N-acyldiazonines as the keto-imine form, while C-acyl isomers exist as the enol-enamine form. The structure of the obtained N- and C-acyldiazonines and their tautomeric transformations were studied by 1H and 13C NMR spectroscopy using two-dimensional 1H–13C HMQC, HMBC, and 1H–1H COSY experiments.
vative sorbent for removing copper(II) ions from water was developed as a composite material based on cellulose and carbon nanotubes. First, a granular sorbent was prepared by dissolving preliminarily ground cotton cellulose fibers in an aqueous alkaline urea solution at –12.5°C, followed by crosslinking with epichlorohydrin and dropwise addition of the resulting transparent cellulose solution to a 12
The effect of laser treatment on the structure and functional properties of multiwalled carbon nanotubes (MWCNTs) synthesized by a microwave method using ferrocene and graphite as precursors, as well as on the electrical and thermophysical characteristics of elastomer nanocomposites based on them, was studied. The MWCNTs were modified by laser ablation using a pulsed Nd:YAG laser with a treatment duration of up to 5 min and a source power of up to 1 kW. The nanocomposites were prepared using the two-component Silagerm 8030 silicone elastomer with a modified MWCNT content of 4 wt
The possibility of obtaining hybrid hydrogels based on sodium alginate and chitosan that acquire form stability through interpolyelectrolyte complex formation was studied. The advantages of such hydrogels include the absence of chemical crosslinking agents, the combination of beneficial physiological properties, and the possibility of controlling the release rate of incorporated drugs by varying the ratio of the polymer components. Hybrid hydrogels were prepared by mixing 2
An improved laboratory method for synthesizing the active pharmaceutical ingredient (API) 3,5-diamino-1,2,4-thiadiazole (Amtizol) was scaled up, the necessary process equipment was selected, and a process flow chart was developed. The proposed technology for producing 3,5-diamino-1,2,4-thiadiazole will reduce its adverse environmental impact by decreasing gaseous emissions during production and will provide a higher yield of the target product. Russian Government Resolution No. 395 of March 27, 2025, provides for the development of veterinary drug production in 2025–2030, making the development of a new veterinary drug particularly relevant. Hypoxia is common in animals and accompanies virtually all diseases. Therefore, an antihypoxic drug was developed. A dispersible tablet was selected as the dosage form because it is convenient for animals and their owners. A competitive analysis revealed that no similar dosage form is available among antihypoxic agents. Excipients were selected to ensure tablet disintegration in the animal’s mouth, mechanical strength, and compressibility, and a dispersible tablet formulation was developed. Tablet samples were prepared in the laboratory, and the identity, dispersibility, and strength of the drug were evaluated. The cost of the finished product was calculated to confirm the economic feasibility of the project, demonstrating that the drug under development will be competitive. Therefore, the proposed formulation can be scaled up by Russian pharmaceutical manufacturers.
This work focuses on the possibility of stabilizing negatively and positively charged micelles of a magnesium hydroxide sol with the water-soluble synthetic physiologically active polymer poly-N-vinylpyrrolidone and on the rheological behavior of the resulting polymer–colloid dispersions. The time during which a polymer–colloid dispersion remains stable should be comparable to the time required to form a material based on it. Therefore, the most important task is to maintain the stability of lyophobic sols during the preparation of materials based on them, for example, through polymer stabilization. This determines the relevance of the present work. Turbidimetric studies showed that mixing poly-N-vinylpyrrolidone solutions with a magnesium hydroxide sol containing either negatively or positively charged colloidal particles results in the formation of polymer–colloid complexes at virtually any ratio of the initial components. The maximum complexation effect is observed at a polymer solution-to-sol volume ratio of 1 : 1. Importantly, polyvinylpyrrolidone stabilizes the micelles of the lyophobic magnesium hydroxide sol, since the presence of polymer macromolecules in the sol unequivocally increases its aggregative stability. Stabilization occurs mainly through specific adsorption and possibly hydrophobic interactions, as well as weak electrostatic or donor–acceptor interactions between the polymer and the micelles. When positively charged colloidal particles of the magnesium hydroxide sol are used, self-organization of the polymer–inorganic system with the formation of topological entanglement network junctions occurs to a greater extent than when negatively charged colloidal particles are used. This opens up possibilities for controlling the physicomechanical properties of polymeric materials produced from the polymer–colloid dispersions studied.
The reactions of unsaturated Meldrum’s acid derivatives with azide ions were studied. The selectivity and reaction pathways were determined for two types of substrates, namely enyne and spirocyclopropane derivatives. The enyne derivative undergoes regioselective Huisgen 1,3-dipolar cycloaddition to form a 1,2,3-triazole, while the trimethylsilyl group remains intact, providing opportunities for subsequent modification of the molecule. In contrast, the spirocyclopropane derivative does not undergo cycloaddition but reacts through nucleophilic opening of the strained three-membered ring to form an organic azide. The structures of all the compounds obtained were confirmed using a combination of spectroscopic methods, including NMR spectroscopy, and elemental analysis. The thermal stability of the synthesized azide was assessed using simultaneous thermogravimetric and differential thermal analysis. The low enthalpy of decomposition indicates that this azide is not an explosive compound. The cytotoxicity of the compounds obtained toward human stromal, lung carcinoma, and melanoma cell lines was evaluated using the MTT assay. The cells remained completely viable at a concentration of 50 μM, indicating the absence of toxic effects under these conditions. A fundamental difference was found between the reactivities of activated unsaturated moieties in Meldrum’s acid derivatives. The developed approaches can be used to obtain new triazole and azide structures of interest as synthons for medicinal chemistry and materials science. The results contribute to the development of methods for selective transformations of highly reactive carbocyclic systems and expand the range of tools available for designing biologically active molecules and functional materials.
The predominant conformation or tautomeric form of a compound can affect the selectivity and yield of the target product in a catalytic process. Nitro-hydroxy-methylazobenzenes are used as reactants in the catalytic synthesis of benzotriazoles and contain two reactive groups that readily interact with hydrogen under hydrogenation conditions. Depending on the position of the nitro group and the orientation of the rings relative to the –N=N– bond, several conformers may be formed, as previously demonstrated for 2-nitro-2′-hydroxy-5′-methylazobenzene. In this study, the structure of 4-nitro-2′-hydroxy-5′-methylazobenzene in the gas phase, in hexane, water, toluene, dimethylformamide, and 2-propanol was investigated using density functional theory (CAM-B3LYP/6-311++G(d, p)) and a continuum solvation model. Experimental and calculated UV and IR spectra were obtained. Only two structures were found both in the gas phase and in the solvents. The lowest-energy conformer is characterized by greater coplanarity and a medium-strength intramolecular hydrogen bond (IMHB) between the β-nitrogen atom of the azo group and the hydrogen atom of the hydroxy group. Intramolecular proton transfer does not occur, and the prototropic equilibrium is shifted toward the azo form. A comparison of the calculation results for 2-nitro- and 4-nitro-2′-hydroxy-5′-methylazobenzene showed that, regardless of the position of the nitro group and the nature of the solvent, ortho-hydroxy-nitroazobenzenes most likely exist exclusively as cis isomers featuring a medium-strength IMHB between the β-nitrogen atom of the –N=N– group and the hydrogen atom of the OH group. At the same time, the calculated IMHB characteristics indicate that the position of the NO2 group affects all hydrogen-bond parameters: its energy, length, and O–H···N angle. An increase in the dielectric constant of the solvent lowers the energies of the conformers and weakens the IMHB.
The dynamics of the polymer composite materials market demonstrate a remarkable rate of adoption of organic fiber-reinforced plastics in major industrial sectors, medicine, sports and household equipment, and household goods. Natural fibers, particularly flax fibers, are of practical interest because of their low cost, environmental friendliness, biodegradability, acceptable mechanical properties, and availability. The expanding use of flax in composite materials imposes new requirements on the quality of flax fiber products. This progress highlights the need for broader studies and deeper knowledge of the possibilities for modifying the physical and mechanical properties of reinforced polymers through fiber pretreatment and selection of treatment conditions with consideration of the required characteristics and operating conditions of composite products. The objective is to analyze recent literature, published mainly over the past three years, addressing the principal issues that hinder the widespread use of flax fiber in the composite industry. Preservation and rational utilization of the natural potential of technical flax fiber in long-fiber forms of reinforcing fillers eliminates the adverse effect of anisotropy in the geometric and mechanical properties of elementary flax fibers. We analyze experience in the use of chemical treatments to overcome the natural porosity and hydrophilicity of flax materials, identify unresolved problems, and search for effective biomimetic approaches to overcoming these difficulties. Information on the structure and functions of the object of biomimicry, the xylem of the flax stem, provides the key to developing moisture-resistant composite materials based on advanced two-stage molding methods using different types of binders.
Volatile organic compounds (VOCs) serve as primary precursors of atmospheric secondary pollution and present substantial risks to the ecological environment and human health. TiO2-based photocatalysis represents a promising approach for VOCs degradation, attributed to its robust oxidation capacity, excellent stability, low cost, and environmentally benign final products (CO2 and H2O). Nevertheless, the wide bandgap, rapid charge recombination, and poor visible-light response of pure TiO2 restrict its practical implementation. This review compiles the recent advancements in modified TiO2 photocatalysts for VOCs abatement, with a focus on three typical strategies: defect engineering, heterostructure construction, and composite system integration. The mechanisms, performance advantages, and existing issues of each strategy are systematically analyzed and compared. Considering the current bottlenecks, such as low quantum yield, intermediate accumulation, and poor adaptability to real-world environments, we put forward future research directions: balancing activity and stability, comprehensively revealing reaction mechanisms, and facilitating industrial translation. This review offers a theoretical foundation for the design of efficient TiO2-based photocatalysts for practical air purification.
A wide range of textile auxiliaries are used as flame retardants. They are required to minimize the risk of ignition in the event of contact with a small heat source, such as a cigarette, candle, or faulty electrical equipment. If the material ignites, the flame retardant slows combustion and prevents the fire from spreading to other objects. Flame-retardant finishing is one of the most important types of textile finishing and can significantly improve the safety of fabrics used for domestic, commercial, public, and industrial purposes. A wide range of chemical formulations are used for flame-retardant finishing. Traditional flame retardants are based on halogens, phosphorus, and nitrogen; however, they have several significant disadvantages: formaldehyde release, generation of hazardous wastewater, reduction in textile strength, changes in fabric shade, and release of toxic gases. Innovative technologies for imparting flame resistance to textile materials are based on plasma, nano-, and layer-by-layer technologies. Flame-retardant coatings based on natural resources are currently of particular interest. This article considers advanced methods for producing flame-retardant coatings: microencapsulation, sol–gel technology, UV curing, and spraying. The combustion mechanism and general classification of flame retardants, as well as the use of boron- and inorganic phosphorus-based flame-retardant formulations, are considered. Particular attention is paid to the use of nanoparticles and natural environmentally friendly resources of animal origin in the flame-retardant finishing of fabrics. The current trend toward the development of environmentally friendly production methods has led to the investigation of harmless, biodegradable substances that are wastes from other industries as flame retardants and have considerable potential for imparting flame-retardant properties to textile materials.
The effects of substituents on the enthalpies of vaporization ΔHvap, determined experimentally or calculated using quantum chemical methods, were analyzed for 21 series of organic and organoelement compounds. Correlation analysis was applied to narrow reaction (indicator) series XBRC, in which the reaction center RC and bridge B remain constant, whereas the electron-donating and electron-accepting properties of substituents X vary. For the first time, the polarizability effect of substituents was found to operate in all the narrow series considered. The polarizability effect is an ion–dipole interaction between the charge q at the reaction center RC and the dipole moment induced by this charge in substituents X. A necessary condition for this effect is therefore the formation of a partial charge q at the reaction center RC. Isolated compounds have no excess charge, and its appearance results solely from the participation of molecules of the series under study in the formation of weak intermolecular complexes. In some cases, the polarizability effect makes a large, sometimes dominant, contribution to the enthalpy of vaporization, outweighing the contributions of the inductive and resonance effects. The steric effect also influences the enthalpy of vaporization in some series. Therefore, a correct interpretation of the substituent effect on the enthalpy of vaporization ΔHvap, that is, on the conversion of a liquid into a gas, requires consideration of the formation of weak complexes by compounds of the series under study. This complex formation gives rise to the polarizability effect on ΔHvap along with the classical inductive, resonance, and steric effects of substituents.
Lithium carbonate is of enormous interest to researchers because of its widespread use as a reagent and its formation as a component of the solid electrolyte during the operation of lithium batteries. This article presents an X-ray diffraction study of the crystal structure of chemically pure monoclinic lithium carbonate. The X-ray diffraction pattern of lithium carbonate was recorded using synchrotron radiation with a wavelength of 0.688199 Å in Debye–Scherrer geometry over a 2θ angular range from 2° to 70° and analyzed by full-profile Rietveld refinement, including refinement of the unit-cell parameters and ion positions. After refinement of the crystal structure, the ion positions in the unit cell were relaxed within the density functional theory framework using the Broyden–Fletcher–Goldfarb–Shanno algorithm implemented in Quantum ESPRESSO, where the atoms were modeled using pseudopotentials. The refined and optimized crystal structures were formally compared by determining the maximum difference between equivalent positions of identical ions, the arithmetic mean of the differences between the coordinates of equivalent positions, and the similarity measure. The thermochemical properties were studied experimentally over the temperature range from 25 to 900°C in a flowing air–argon mixture using a simultaneous thermal analyzer in thermogravimetric analysis–differential scanning calorimetry mode. The resulting data were used to determine the melting point of lithium carbonate and to discuss its mass loss, decomposition mechanism, and possible interaction with the crucible material over the specified temperature range.
Reduced graphene oxide (rGO) was synthesized via an eco-friendly green route using Azadirachta indica (neem) leaf extract as a natural reducing and stabilizing agent. Graphene oxide (GO) was first prepared using a modified Hummers’ method and subsequently reduced through the action of phytochemicals present in the neem extract, thereby eliminating the need for hazardous chemical reductants. Structural and morphological characterization using XRD, FTIR, Raman spectroscopy, and SEM confirmed the effective reduction of GO, partial restoration of the sp2-carbon network, and the formation of wrinkled, porous rGO structures suitable for adsorption applications. The adsorption performance of the green-synthesized rGO was evaluated using real industrial wastewater collected from the Kanpur industrial region, containing hexavalent chromium (Cr6+), lead (Pb2+), cadmium (Cd2+), and textile dyes.
The synthesis of a series of fluorescent 1H-pyrazole derivatives was described. The photophysical properties of the synthesized derivatives were investigated using ultraviolet-visible (UV-Vis) spectroscopy and fluorescence spectroscopy. The results showed that the synthesized compounds exhibited only minor variations in fluorescence emission in solution; upon aggregation into the solid state, the emission wavelength exhibited a significant red shift and the emission intensity was markedly enhanced, among which eight compounds displayed typical aggregation-induced emission (AIE) characteristics. To investigate the anti-inflammatory potential of our multifunctional synthesized compounds, we evaluated the inhibitory effect of synthetic compounds on LPS-induced inflammation in MH-S cells. The anti-inflammatory activity screening revealed that three target compounds possessed significant anti-inflammatory activities.
A novel antibacterial fluoroquinolone molecule (PFQA) that demonstrated poor solubility in the biologically relevant media was synthesized. Influence of 2-hydroxypropyl-β-cyclodextrin (HPβCD) on the physicochemical and potential biological properties of PFQA was studied. HPβCD increases the PFQA’s solubility (up to 2 times), decreases the drug’s particle size (up to 100 nm) and significantly enhances particle’s homogeneity. The mechanism of complex formation was investigated by FTIR and 1H NMR. PFQA has two binding sites for HPβCD with Kd1 = (5.8 ± 0.8) × 10–4 M and Kd2 = (2.9 ± 0.3) × 10–3 M. The negative cooperativity is possibly due to the steric effects proved in Scatchard and Hill coordinates. The results highlight the great advantage of PFQA−HPβCD comparing to free PFQA for further studies in vitro and in vivo.
In this study, a series of N-(2-acetoxybenzoyl)amino acid esters were synthesized. The title compounds were assessed for both their antifungal activities against six phytopathogenic fungi and their anti-proliferative activity against HCCLM3 and MCF-7 cell lines. The results demonstrated that these compounds possessed modest yet definite antifungal activity against the selected phytopathogens. Notably, methyl N-(2-acetoxybenzoyl)tryptophanate exhibited significant dual functionality, achieving 88.9
