Cyanine dyes are one of the most commonly used classes of fluorescent probes. All Cy5 fluoresce at ~ 660 nm, while Cy7 emit in the near-infrared range (700–900 nm), making them particularly suitable for biomedical applications due to reduced tissue autofluorescence in this spectral region. The fluorescence intensity of cyanine dyes typically increases upon conjugation with biomolecules such as nucleic acids. Furthermore, their fluorescence can be significantly modulated through duplex formation between dye-modified single-stranded DNA and its complementary sequence. In this study, we investigated physicochemical properties of a series of Cy5 and Cy7 derivatives with substituents of varying lengths at distinct molecular positions in both single-and double-stranded DNA conjugates.

Conditions have been investigated and methodical techniques have been developed for functionalization of micro-, nanopowders of aerosil, titanium dioxide and diatomaceous earth based on vapor phase condensation of agents with low surface energy (tetraethoxysilane and stearic acid) in order to give them phobno/philic properties, as one of the requirements for creating materials or coatings with bulk superhydrophobicity Using IR spectroscopy, derivatography, scanning electron microscopy and x-metry, the mechanism of interaction of hydrophobic agents with the surface of the above powders and changes in their properties were investigated as a result of hydrophobization. Suspensions of functionalized powders in fluorinated lacquer were used for hydrophobization of various substrates: glass, aluminum, steel, fabrics and papers). The highest value of the marginal angle of wetting with water (170°) was achieved for coatings on aluminum obtained using a composition containing functionalized aerosil. Superhydrophobic coatings on the surface of steel, aluminum and glass with a marginal wetting angle in the range of 150–170° and a rolling angle of less than 10°, paper and fabric with volumetric hydrophobicity (150–170°) were obtained, retaining this property under normal operating conditions for at least 6 months and at elevated relative humidity (more than 80 %) for at least 1 month.

By reacting of rosin resin acids with citraconic anhydride at 140–180 °C for 2–4 hours, rosin-citraconic anhydride adducts with varying contents of citraconopimaric acid (from 30 to 55 %) were synthesized. When treating rosin-citraconic anhydride adducts with primary aliphatic amines (octyl-, octadecylamine) and aniline, the corresponding nitrogen-containing derivatives were obtained. The thermal stability of rosin-citraconic anhydride adducts and their modifying effect on the properties of unfilled elastomer compositions and filled industrial rubber mixtures and their vulcanizates were studied. It has been established that the most effective modifier is a rosin-citraconic anhydride adduct containing 55 % citraconopimaric acid octylimide (ORCA) with increased thermal stability (265 °C). This additive reduces Mooney viscosity by up to 30 % and increases the vulcanization rate of production tire rubber compounds by 40 %, which reduces the energy intensity of technological processes. The ORCA modifier improves the properties of rubber: it increases the resistance of rubber to high temperatures (90 °C) in a steam-air environment with an increase in the strength of the bond between rubber and textile cord by 43.8 %; reduces the mechanical loss tangent to 0.235, which makes it possible to reduce heat generation under dynamic influences on the product; increases abrasion resistance by 14 % and resistance to thermal aging by 10 %.

By the condensation of 1-oxo-1,2,3,6,7,7a-hexahydrohydro3a,6-epoxyisoindole-7-carboxylic acids with 4-aminoantipyrine or N-methyl-1-[5-(p-tolyl)isodiesol-3-yl]methylamine in the presence of dicyclohexylbisodiimidine in a dichloromethane medium, corresponding amides with a yield of 67–78 % were synthesized. By the interaction of 1-oxo-1,2,3,6,7,7a-hexahydro-3a,6-epoxyisoisoindole-7-carboxylic acids with 4-aminoantipyrine or N-methyl-1-[5-(p-tolyl)isodioxol-3-yl]methylamine in methanol, corresponding ammonic salts with a yield of 93–97 % were obtained. Quantumchemical modelling of energy parameters and electronic structure of synthesized compounds by ab initio method, with the level of theory B3LYP1/MIDI, was carried out in order to preliminary assess their potential antibacterial and antiviral properties. The antimicrobial activity of the synthesized compounds against the strains Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 11229 was studied.

Bioanalytical systems specific to Salmonella enterica bacteria have been developed and studied. The systems are based on the immunochemical binding of lipopolysaccharide (LPS) antigens of these pathogenic microorganisms to mono- and polyclonal antibodies conjugated with a europium chelate. The quantitative determination of the cells was carried out in immunoassay systems by measuring the Eu³⁺ time-resolved fluorescence (dissociation-enhanced lanthanide fluorescence immunoassay, DELFIA) systems. In the DELFIA microplate system, comprising labeled polyclonal antibodies in solution and a LPS-protein conjugate on the solid-phase, the following analytical parameters were achieved: cell concentration measurement range – from 10⁴ to 10⁷ CFU/ml, sensitivity (IC₅₀) – 3 · 10⁵ CFU/ml, the limit of detection (IC₁₀) – 1.5 · 10⁴ CFU/ml, and the coefficient of variation – from 4,5 to 8.0 %. The broad specificity of this system enabled to detect Salmonella enterica of various serotypes. The possibility of testing samples of culture medium and milk without prior dilution was demonstrated. The recovery rate of samples containing Salmonella enterica was found to be 88–110 %. The presented development can serve as the basis for a practical kit of reagents to monitor Salmonella enterica bacteria in food products.

The paper describes experimental studies of changes in the chemical composition of aviation oils during their thermal conversion. Aviation oils widely used in the aviation industry of the Republic of Belarus were taken as research objects: MS-8P, TURBONIKOIL 98 (TN 98) and TURBONIKOIL 600 (TN 600). A description of the operating conditions of oils, including thermal conditions, is provided. It is noted that, although the oils in question are thermally stable over a wide temperature range, at various stages of operation they might be overheated, leading to a quantitative change in the hydrocarbon composition. This can lead to a significant decrease in lubricating properties, the formation and accumulation of mechanical impurities in the friction unit, the formation of defects, and destruction of friction unit elements. A description of the methodology for determining the quantitative and qualitative analysis is presented. During the study, the chemical composition of the starting oils was determined, after which the oils were heated for a certain period of time. Warm-up temperatures were selected from the maximum operating temperatures at which these oils are used to the minimum flash points. For convenience, the oil components were divided into eight groups of components. An analysis of changes in the percentage of groups of components of the studied oils during their heating is presented. The effect of heating time on the component composition of these samples is shown, esters, additives and other organic compounds are determined. The results obtained can be useful in modeling the operation of friction units of aircraft engines and predicting changes in oil quality indicators under operating conditions.

The transfer of livestock farming to an industrial basis and the construction of large pig and poultry complexes lead to a significant concentration of manure at such enterprises. A technology has been developed for deep processing of pig manure and chicken manure for their subsequent use as an organic component of complex organomineral fertilizers. One of the key stages of the proposed technology is the treatment of manure with chemical reagents, allowing to achieve the effect of its deodorization and disinfection. The developed technology makes it possible to obtain granulated organomineral fertilizers based on treated manure masses.

Antioxidant system of malignant cells interferes with cancer chemotherapy. The influence of pyrocatechol on the oxidation of propanol-2 by atmospheric oxygen during the radiolysis of its 1 M aqueous solutions was studied. Adding 0.01 M pyrocatechol to the solution reduced the intensity of oxidation and the formation of acetone. The yield of acetone increased with the joint presence of pyrocatechol and iron ions in solution. It has been shown that Fe²⁺ ions can suppress the antioxidant effect of the diphenolic antioxidant pyrocatechol.