Hydrated aluminum oxide is widely used in various fields – from catalyst production to medicine. Several modifications of hydrated aluminum oxide are known, including gibbsite, bayerite, nordstrandite, pseudoboehmite, and boehmite. Of particular interest is the synthesis of Al₂O₃ · nH₂O with a pseudoboehmite structure, which represents a highly dispersed aluminum hydroxide with a developed specific surface area. This study investigates the influence of aluminum salt concentration and type, aging temperature, and duration on the phase composition, properties of the resulting hydrated aluminum oxide precipitates, and their structural and adsorption characteristics. It is shown that the precipitates obtained from sulfate, nitrate, and chloride solutions by ammonia neutralization exhibit poor filterability, with filtration coefficients in the range of 6.7 · 10⁻⁵ to 7.8 · 10⁻⁷ m/s. It was found that slightly crystallized pseudoboehmite forms from chloride- and nitrate-containing solutions with anion concentrations of 1.8 mol/L, whereas X-ray amorphous products form from sulfate-containing solutions of the same concentration. Dilution of the sulfate system to 0.9 mol/L SO₄²⁻ leads to the formation of crystalline pseudoboehmite, and further dilution to 0.3 mol/L SO₄²⁻ results in gibbsite formation. Lowering the aging temperature of the precipitates to 40 °C leads to the formation of poorly crystallized pseudoboehmite. This product is a powder composed of non-isometric particles sized 20.0–50.0 µm. The specific surface area of pseudoboehmite synthesized from aluminum sulfate was found to be higher than that of samples obtained from aluminum nitrate and chloride solutions, reaching 407.41 m²/g. This is attributed to the presence of pores with diameters of 3.826–4.544 nm – approximately 1.5 times smaller than those in the nitrate- and chloride-derived samples.

The surface properties of amines with different molecular structures, including an aliphatic amine (alkylammonium chloride), an alicyclic amine (alkylmorpholine), and an aromatic amine (benzethonium chloride), were investigated in aqueous and sodium chloride solutions. The critical micelle concentration, surface activity, adsorption at the solution/air interface, and the minimum area occupied by an amine molecule at the interface were determined. It was shown that the critical micelle concentration decreases, while surface activity and adsorption at the surfactant solution/air interface increase when transitioning from aliphatic to alicyclic and aromatic amines, and also in the presence of a low-molecular-weight electrolyte.

A model of the phase-boundary potential of ion-selective electrodes is presented, combining the simplicity of steady-state approaches with the ability to describe the dynamic response characteristic of dynamic diffusion models. Within the framework of the proposed model, equations were obtained that explicitly describe the dependence of the phase-boundary potential of potentiometric sensors on time, observed when working with highly selective electrodes in solutions of foreign ions, as well as in mixed solutions containing foreign and primary ions, in particular, when determining the selectivity coefficients using the methods recommended by IUPAC. An advantage of the proposed model is the minimization of computational time to fractions of a second (in contrast to the numerical solution of systems of differential equations within known analogs, which requires tens of minutes). By obtaining equations in analytical form, the proposed approach eliminates the need for resource-intensive computer algebra systems (such as Wolfram Mathematica) and enables the rapid calculation of the response of ion-selective electrodes. The high predictive ability of the developed model is confirmed by comparing the calculation results with experimental data on the dynamics of changes in the response of tetrabutylammonium- and picrateselective electrodes in solutions containing foreign ions, and with the results obtained within the framework of the interface-equilibria-triggered dynamic diffusion model.

The antiviral activity of 17 adamantane containing nitrogenous heterocyclic compounds against the vaccinia virus in Vero cell culture was studied and the data obtained were compared with the results of ab initio quantum chemical calculations using the DFT method (density functional theory). By analyzing the calculated descriptors of the studied molecules, namely, the energy differences of the frontier molecular orbitals and dipole moments, as well as their antiviral activity data, a convenient method for pre-screening the least active compounds has been developed, which allows for the optimization of the search process for new biologically active substanses.

Complex compounds based on manganese (II) chloride crystal hydrate MnCl2 ∙ 4H2O with amino acids of different classes, such as aliphatic – glycine and heterocyclic – histidine and tryptophan have been synthesized and identified with IR spectroscopy, differenti-al thermal analysis, electron microscopy and elemental analysis. Using elemental analysis and electron microscopy we determined chemical composition of the complex as [NH2CH2COO]2Mn ∙ 2H2O. The catalytic oxidative activity of [NH2CH2COO]2Mn ∙ 2H2O comples has been tested in the model reaction of aerobic oxidation of isopropyl-benzene (cumene). [NH2CH2COO]2Mn ∙ 2H2O complex demostrated high catalytic activity and accelerated the reaction by 10 times compared to the control sample. The tests for biological activity demonstrate antibacterial, antiviral and psychotropic properties of synthesized complexes.

The article presents the results of research on the effect of two-stage acid-base treatment on the component composition, structure and whiteness index of short flax fiber provided by the Republican Unitary Industrial and Trading Enterprise “Orsha Flax Processing Plant”. Pretreatment with 1.0 % nitric acid for 1 h followed by alkaline cooking with sodium hydroxide solutions with a concentration of 1.0‒5.0 % for 1‒5 h made it possible to establish that an increase in alkali concentration and cooking time contributes to a decrease in lignin content from 5.9 to 0.25 % and ash content from 1.2 to 0.3 %, while the content of alpha-cellulose increases from 84.0 to 95.4 %. Data analysis shows that the two-stage processing of short flax fiber significantly increases the whiteness of cellulose, providing a maximum increase in the whiteness index when using 5.0 % alkali solution for 5 h of treatment. This is due to the intensive removal of coloring components, mainly lignin, pigments and extractives. The data obtained indicate that nitric acid treatment provides the key technological advantages of the two-stage process: short process time, cooking at atmospheric pressure and low temperature. These findings make it possible to increase the efficiency of the process for obtaining high-quality cellulose from short flax fiber.

A technology for determining the fiber composition of paper using IR-ATR spectroscopy is proposed and described, allowing for increased rapidity and representativeness of the measurements. The technology includes microscopic identification of a certain type of fiber in the paper composition; and determination of the percentage content of fibers other than hardwood and softwood kraft pulp, using the obtained calibration dependencies. The experiment involved standard laboratory handmade sheets of two types with different fiber compositions: from softwood and hardwood bleached commercial kraft pulp (in a 50 : 50 ratio) with the addition of bleached chemical-thermomechanical pulp instead of hardwood and softwood in an amount of 5 to 40%; and from unbleached kraft softwood (kappa number 21) and hardwood (kappa number 16) pulp, into the composition of which unbleached bamboo pulp (kappa number 17) was introduced in an amount of 10 to 50 %. Using IR-ATR spectroscopy, it was found that an increase in the proportion of bleached chemical-thermomechanical pulp or bamboo pulp leads to systematic changes in the spectral characteristics of the paper, due to differences in the content and composition of lignin, hemicelluloses and extractive substances of the paper components. To quantitatively assess the changes in the spectra, the intensity ratios of the analytical bands were selected that are independent of the spectrum recording conditions: 1 500, 1 400, 1 110 cm–1 for bleached chemical-thermomechanical pulp and 1 070, 667, 1 736, 1 580 cm–1 for bamboo pulp. Based on the established calibration relationships, regression equations were derived for determining the bleached chemical-thermomechanical pulp or bamboo pulp content in paper samples based on the intensity ratio of analytical bands in IR spectra. The proposed method significantly outperforms traditional chemical and microscopic approaches in terms of speed, reproducibility, and labor costs and can be useful in pulp and paper mills for the rapid monitoring of compositions.

Brassinosteroids (BRs) constitute a unique class of polyhydroxylated steroidal phytohormones that regulate plant growth, development, and stress responses. A defining and conserved structural feature of all biologically active BRs is in the presence of vicinal 1,2-diol motifs, most prominently at the 2α,3α-positions of the A ring and at the 22,23-positions of the side chain. These cis-diol functionalities impart chemical properties that distinguish brassinosteroids from all other major phytohormone classes and enable reversible coordination with boron species. This review summarizes analytical, chemical, and physiological evidence supporting the concept of 1,2-diol brassinosteroids as boron-responsive phytohormones, highlights parallels between boronate derivatization chemistry and in vivo boron complexation, and proposes boron coordination as a previously underappreciated regulatory layer in brassinosteroid biology. Integrating inorganic chemistry with plant hormone signaling allows improving our understanding of brassinosteroid evolution, transport, and function, and positions 1,2-diol BRs as a model system for mineral–hormone co-regulation in plants.