Вестник Башкирского университета

Improvement of oil quality using cavitation sonar devices

2024-12-28T07:41:02+00:00

The article presents research on improving the quality of oil containing organochlorine compounds (OOC). A decrease in the concentration of COC in oil is achieved by their hydrolysis. XOC hydrolysis is carried out by mixing oil with an alkali solution in a molar ratio with XOC in the range of 3-10:1, after which the mixture is treated with a cavitation sonar device until the oil temperature rises by 5-50 ° C. Due to this, the degree of purification of oil from organochlorine compounds increases. The content of COC in oil is reduced to 1.96 micrograms/kg.

DOI: 10.33184/bulletin-bsu-2026.1.4

Study of amino acid composition of crushed flaxseed

2025-09-26T14:20:01+00:00

The study of large-scale industrial waste from the processing of food products of plant origin is important because it creates the prerequisites for obtaining new sources of biologically active compounds. From this point of view, linseed meal is of great interest, accumulating in significant quantities after obtaining linseed oil from oilseed varieties (Linum usitatissimum). The purpose of our study is to study the amino acid composition of flax meal and to establish the main characteristics of amino acid balance. The amino acid composition was determined on an automatic INGOS AAA 500 analyzer with Clariti – chromatography Software. The obtained experimental data allowed us to conclude that the amino acid composition of flax meal is characterized by the presence of: crude protein - 33.74%, the sum of amino acids in the hydrolysate - 28.97%, essential amino acids - 8.55%, and replaceable amino acids - 20.42%, among them, glutamic acid dominates - .8,12%, the lack of which affects the nervous and immune systems. Mathematical processing of the obtained results allowed us to evaluate the protein as a whole. The amino acid scores of essential amino acids were calculated. The limiting biological value of the protein fraction of flax meal is determined by the amino acid cystine, which has detoxifying, antioxidant, reparative, wound healing, and mucolytic effects. A comparison of the SCOR of cystine and other essential amino acids allowed us to establish the following characteristics: the amino acid composition imbalance ratio of the SCOR = 10%, the biological value of the protein BV = 90%, and the essential amino acid index EAI = 0.598. These results indicate a highly balanced amino acid composition of the protein complex in the dry extract and a close approximation to an ideal protein.

DOI: 10.33184/bulletin-bsu-2026.1.5

Synthesis of polyheteroarylenediphthalides based on 2,4-dibenzoylisophthalic acid pseudochloride

2025-11-11T06:09:01+00:00

The self-condensation of 2,4-dibenzoylisophthalic acid pseudochloride and its copolycondensation with other pseudochlorides were carried out by the reaction of reducing dehalogenation. The structure of synthesized polyheteroarylene diphthalides has been studied using ¹³C NMR spectroscopy. The thermal properties of polymers have been studied by thermogravimetric analysis and it has been shown that they are heat-resistant.

DOI: 10.33184/bulletin-bsu-2026.1.6

Ionization and adsorption of polyarylenephthalides on a solid substrate and at the sulfuric acid/tetrachloroethane interface

2025-12-10T22:05:09+00:00

The sulfuric acid concentrations at which protonation (ionization) and dissociation of the lactone ring of the phthalide group begin in homopolymers of polydiphenylene oxide phthalide (PDPO) and polyterphenylene phthalide (PTP), as well as the block copolymer PTP₁₂₅PDPO₁₈, were determined both in thin films cast on a glass substrate and in films formed at the sulfuric acid/tetrachloroethane interface. Spectrophotometric titration of sulfuric acid solutions of these polymers was carried out, and the regions of existence of swollen polymer coils of ionized macromolecules and dense globules, in which the protonated lactone ring forms an unshared ion pair with the hydrosulfate ion, were determined for each of them. Three ranges of H₂SO₄ concentrations were determined, in which the homopolymers and the corresponding copolymer blocks have different degrees of ionization and different supramolecular structures.

DOI: 10.33184/bulletin-bsu-2026.1.7

Electrochemical reduction of carbon dioxide in the presence of various background electrolytes

2025-12-24T12:59:05+00:00

The electrochemical reduction of carbon dioxide (CO₂) into fuels or commercial chemicals is an important process for completing the carbon cycle caused by human activities. In this context, electrolytes play a key role, as the interactions between the electrocatalytic surface and the electrolyte significantly affect the reaction mechanism and the final products of CO2 reduction. Understanding the influence of electrolytes is necessary for the design of efficient electrochemical devices capable of converting CO₂ into valuable products.

DOI: 10.33184/bulletin-bsu-2026.1.8

Influence of black currant (Ribes nigrum l.) Juice of bashkir-bred cultivars on the ethanol oxidation process

2025-10-01T11:10:09+00:00

The study investigated the influence of juice from berries of black currant (Ribes nigrum L.) cultivars bred in Bashkortostan (Belskaya, Bobrovaya, Valovaya, Karaidel, Estafeta, Chishma, Kushnarenkovskaya, Iremel, Truzhenitsa) on the radical-chain oxidation process of ethanol. The ability of R. nigrum juice to reduce the oxidation rate was quantitatively assessed by the relative reduction in the ethanol oxidation rate. The antioxidant activity of R. nigrum juice was shown to depend on both the cultivar and the volumetric fraction of juice in the reaction medium. The highest effect was observed for the cultivar Estafeta (up to 62.8%). The applied method demonstrated high sensitivity and suitability for assessing antioxidant activity.

DOI: 10.33184/bulletin-bsu-2026.1.9

Influence of rayleigh number on the passive cooling of a heat-generating solid body

2025-10-10T08:25:46+00:00

A numerical study has been conducted to assess the convective heat transfer inside an enclosure containing a heat-producing element. The vertical sides of an enclosure are kept at a constant temperature, while the horizontal boundaries are thermally insulated. Heat generating element is assumed to be placed in the central part of the considered cavity. The governing system for the considered problem is tackled by adopting the control volume approach. Rayleigh number (10⁴ < Ra < 10⁶) and the walls emissivity (0 < eps < 1) are the governing parameters. The influence of the specified parameters on the stream function and temperature isolines, as well as the convective and radiative Nusselt numbers, are presented. Results concluded that the surface emissivity of boundaries and Rayleigh number have a considerable impact on the cooling efficiency of the heat- producing body.

doi 10.33184/bulletin-bsu-2026.1.1

Numerical analysis of the acoustic wave scattering mechanism on two sound-permeable spheres

2025-11-10T12:19:36+00:00

An analysis of acoustic wave scattering by two sound-permeable spheres exposed to a monopole radiation source is conducted. The analysis was performed using a numerical technique based on the orthogonal central compositional design method. This technique was implemented for a three-factor computational experiment, where one physical and two geometric parameters of the system were selected as factors. The objectives of the study are to identify factors whose changes significantly affect the entire system; find the values of the variable parameters for which the objective function takes optimal (minimum and maximum) values; and study the system at optimal parameter values. It is shown that the system with droplets is insensitive only for small wave radii, while the system with bubbles is insensitive only for large wave radii. Pressure distribution diagrams constructed for optimal system parameters made it possible to identify zones of pressure increase and decrease, which are highly dependent on the physical properties of the media.

Numerical method for calculating eigenfrequencies of bending vibrations of a rod with an absolutely rigid intermediate insert

2026-02-20T10:00:33+00:00

The article presents a numerical technique for calculating natural frequencies of bending vibrations of a rod with an absolutely rigid intermediate insert, based on the method of fifth-degree algebraic polynomials. The rod is modelled as a composite system consisting of three sequentially connected segments. The two outer segments (root and top) represent curvilinear portions of the rod with flexural rigidity EI and mass per unit length ρA, governed by a fourth-order differential equation of vibrations. The middle segment, corresponding to the insert zone, is modelled as an absolutely rigid, undeformable element described by a straight line. To verify the numerical method, a benchmark problem with an exact analytical solution was solved. It is demonstrated that with sufficient mesh density along the rod length, the method provides agreement between calculated values and the reference solution up to the sixth decimal place.

doi 10.33184/bulletin-bsu-2026.1.3