Вестник Башкирского университета

Influence of micro‑tube tilt angle on the temperature profile in convective PCR: Numerical simulation and statistical analysis

2025-12-25T17:50:36+00:00

The study investigates how the tilt angle of a standard 50 µL polypropylene micro-tube affects the temperature regime of convective polymerase chain reaction (PCR). The fluid flow is modeled using the Boussinesq approximation as implemented in the OpenFOAM suite. Water serves as the working medium. DNA molecule motion is simulated with a Monte Carlo approach: randomly placed particles are advected through the computed velocity field, and their temperature is recorded at each tracking step. For the range of tilt angles from −90° to +90°, computational-experiment data were obtained, histograms of particle residence times within specified temperature intervals were constructed, and a heat map was generated. The results show that tilting the tube to the right (positive angles) lowers the dominant temperatures, whereas tilting it to the left (negative angles) shifts the temperature range upward. These findings enable optimization of convective PCR parameters simply by adjusting the micro-tube’s tilt angle and boundary temperatures, potentially enhancing the sensitivity and reliability of portable PCR systems.

DOI: 10.33184/bulletin-bsu-2025.4.1

Calculation of swirling polydisperse flows in vortex-type devices

2025-09-10T11:50:09+00:00

Based on the model of interpenetrating continuums, a scheme for calculating the interaction of swirling flows in the working zone of a vortex dust collector has been developed. Carrier and dispersed phase streamlines for primary and secondary flows have been obtained. A scheme for calculating the efficiency of dust collection is proposed, which makes it possible to find the efficiency of gas and dust flow purification for any fractional composition of dispersed dust in a wide range of changes in determining parameters.

DOI: 10.33184/bulletin-bsu-2025.4.2

Optimal heating speed for an unbounded plate, taking into account thermal stress constraints

2025-12-25T18:23:53+00:00

This paper examines the problem of optimal axisymmetric heating of an infinite plate, taking into account the resulting thermal
stresses. The dependence of the ultimate strength and thermal conductivity on temperature is considered. A sequential linearization method is used to solve the resulting nonlinear problem. Based on the developed approach, an algorithm is proposed for selecting the optimal temperature regime in terms of response time, satisfying the imposed constraints. Example calculations are provided demonstrating the algorithm's effectiveness. The obtained results can be used in the development of high-temperature heating technologies.

DOI: 10.33184/bulletin-bsu-2025.4.3

Mechanism of stability of Water Bridge

2025-09-15T17:21:27+00:00

The paper proposes a new mechanism for the dynamic stability of a water bridge that occurs between two dielectric containers with distilled water under the action of a constant high-voltage voltage between cylindrical electrodes. Based on the experimental results and calculations, it is established that the cause of the dynamic equilibrium of the bridge is the electric wind.

DOI: 10.33184/bulletin-bsu-2025.4.4

Continuous monitoring of fine-dispersed aerosols in technogenic environments

2025-09-05T10:24:38+00:00

Indoor air quality plays a crucial role in maintaining human health and preventing respiratory infections. In conditions of high population density, the concentration of bioaerosols — microscopic particles released during breathing, speaking, and coughing — increases significantly, and these particles can act as carriers of pathogens. The fraction, which includes particles with a diameter of less than , is of particular importance due to its ability to deeply penetrate the respiratory tract and remain suspended in the air for extended periods. This paper presents the results of measurements of indoor air parameters ( , , , temperature, humidity) conducted using a custom-developed device in residential, office, and public spaces. It is shown that under conditions of high occupancy, a significant increase in and concentrations occurs, correlating with human activity and ventilation patterns. The levels in crowded rooms were found to reach up to , while concentrations exceeded 1800 ppm, indicating insufficient ventilation. The obtained data confirm that monitoring in combination with and enables the assessment of bioaerosol accumulation and the identification of potentially hazardous conditions. The developed device demonstrates high sensitivity and suitability for integration into early warning systems for airborne transmission of infectious diseases.

DOI: 10.33184/bulletin-bsu-2025.4.5

Binding energy and ionic conductivity in copper and silver chalcogenides Ag2-δCuδX (X = S, Se, Te)

2025-09-08T08:37:42+00:00

In this paper, calculations of the binding energy in copper and silver chalcogenides Ag_2-δCu_δX (X = S, Se, Te) were performed using the BIOVIA Materials Studio DMol3 software package. It was found that one of the factors affecting the ionic conductivity is the binding energy. With anionic substitution of Te-Se-S in Ag_2-δCu_δX compounds, the binding energy decreases, which promotes the transition of cations to a mobile state and, accordingly, leads to an increase in ionic conductivity.

DOI: 10.33184/bulletin-bsu-2025.4.6

On measuring the radial electric field strength in a low-temperature gas discharge plasma

2025-11-17T07:15:15+00:00

Abstract. This paper presents the results of measurements of the radial plasma potential distribution based on the floating potential difference of a movable probe. These measurements reveal anomalously high electric field strengths across the discharge tube cross-section, located in an axial magnetic field. The effect of varying the thickness of the near-probe layer due to the uneven radial distribution of the electron density across the discharge cross-section is demonstrated.

DOI: 10.33184/bulletin-bsu-2025.4.7

Synthesis and structural investigation of the ytterbium complex with glycine

2025-04-07T12:15:52+00:00

A method for obtaining a new complex of ytterbium with glycine of the composition [Yb(Gly)3(H2O)2](ClO4)3•H2O is described. The compound was obtained in the form of single crystals, which crystallized in a monoclinic system with space group C 2/c (unit cell parameters: a = 20.4878(3) Å, b = 9.24580(10) Å, c = 24.0258(4) Å, α = γ = 90°, β = 100.368(2)°, V = 4 476.80(11) Å3 ). The crystal structure is an infinite chain in which the coordination polyhedron of the ytterbium atom has the shape of a double-capped trigonal prism.

DOI: 10.33184/bulletin-bsu-2025.4.8

Synthesis of mannich bases of methyl ester of 2,3-indolo-betulinic acid

2025-04-16T10:24:36+00:00

The reaction of methyl ester of 2,3-indolobetulinic acid with propargyl bromide in the presence of NaH yielded a derivative containing a terminal triple bond in the indole ring. Subsequent aminomethylation using paraformaldehyde and a secondary amine in the presence of a monovalent copper (CuI) catalyst led to new Mannich bases of interest as potential pharmacologically significant compounds.

DOI: 10.33184/bulletin-bsu-2025.4.9

Application of IR spectroscopy and PLS regression for quantitative analysis of model asphaltene solutions in toluene

2025-07-21T17:08:23+00:00

A method for the quantitative analysis of model asphaltene solutions in toluene using infrared spectroscopy and chemometric techniques is presented. Solutions with concentrations of 2–10 wt.% were studied using the i-Red 7800 u-L spectrometer. Absorption bands characteristic of functional groups in asphaltenes were analysed. To improve the accuracy of quantitative determination, multivariate data analysis methods were applied – principal component analysis and partial least squares. The resulting regression model showed a high degree of agreement between measured and predicted concentration values. The obtained results demonstrate the potential of the proposed approach for rapid analysis and quantitative assessment of asphaltenes in organic solutions.

DOI: 10.33184/bulletin-bsu-2025.4.10

About recycling of polyethylene terephthalate waste

2025-11-19T07:31:50+00:00

The possibility of involving the waste obtained during the processing of recycled polyethylene terephthalate in reuse is considered. It is shown that the real way to recycle recycled polyethylene terephthalate is to recycle it together with the primary polymer. It is argued that the addition of a secondary polymer to the primary polymer generally leads to a significant increase in the modulus of elasticity, but is accompanied by a decrease in the values of breaking stress and tensile elongation.

DOI: 10.33184/bulletin-bsu-2025.4.11

Поправка

2025-12-25T20:21:34+00:00

В предыдущем номере журнала – «Вестник Башкирского университета». 2025. Т. 30. №3 – при сборке
номера была допущена техническая ошибка, в результате которой статья «Численное моделирование тепловой
конвекции в дисперсных системах с учетом процесса седиментации дисперсной фазы» (авторы: Э. Э. Сахибгареев, А. А. Мусин, Л. А. Ковалева) вместо раздела «Математика и механика» была размещена в разделе «Химия».
Редакция приносит свои извинения за допущенную ошибку

Index

2025-12-25T20:27:15+00:00

Index