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Investigation of chemical power sources on an automated electronic load with controlled parameters

https://doi.org/10.58224/2619-0575-2024-7-4-25-36
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 25-36 p.
Abstract
Hybrid installations for converting fuel energy into electricity are a promising way to provide humanity with affordable energy resources. However, the issue of obtaining reagents (hydrogen and oxygen) with high purity remains one of the most urgent. In this work, the energy characteristics of a hydrogen-oxygen fuel cell in combination with a water electrolyzer were investigated. Membrane-electrode assemblies were formed consisting of a modified membrane based on polytetrafluoroethylene with a platinum-containing component (Pt(30%)/C), as well as an anode and cathode made of carbon fabric and porous nickel doped with technical carbon and graphene. The structural characteristics of the material were studied using the scanning electron microscopy method. For the first time the investigation of hydrogen-oxygen membrane-electrode assemblies energy characteristics was carried out on an automated electronic load AKIP-1375/1E with embedded software. In the developed hydrogen-oxygen fuel cell, a more affordable commercial polytetrafluoroethylene-based membrane was used as a solid polymer elec-trolyte instead of the Nafion membrane, which significantly reduced the cost of developed MEA. As a result of the tests carried out, it was found that the maximum specific power is demonstrated by elements constructed on the basis of an anode and a cathode made of porous nickel modified with graphene.
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Conductive polymers as transparent electrodes: structure, functional characteristics, preparation methods, applications

https://doi.org/10.58224/2619-0575-2024-7-4-37-47
 37-47 p.
Abstract
This paper provides a comprehensive review and analysis of the current state and advancements in major transparent conducting polymers, which are considered promising alternatives to traditional transparent electrodes based on metal oxides, such as indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO). These polymers possess unique properties, including flexibility, light weight, and ease of integration into flexible and stretchable optoelectronic devices, making them highly attractive for use in organic light-emitting diodes (OLEDs), thin-film transistors, solar cells, sensors, flexible displays, and a range of other applications. The paper presents publication statistics for this research area over the past 10 years based on data from the Scopus database of peer-reviewed scientific literature. It briefly discusses the conduction mechanisms in these polymers, which influence key properties such as electrical conductivity, transparency, and stability under external factors. Various methods for producing these polymers are examined, including chemical deposition, electrochemical techniques, and the incorporation of conductive nanoparticles to enhance functional characteristics. The analysis culminates in a summary table containing data on the transparency, conductivity, and other functional properties of different polymer materials, facilitating their selection for specific applications. Additionally, the paper addresses the prospects and challenges associated with the use of these polymers in flexible electronics, next-generation displays, and other emerging technologies where traditional materials may be less effective or practical.
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Rheological properties and structure formation of a mineral suspension with a complex organic and mineral additive

https://doi.org/10.58224/2619-0575-2024-7-4-48-63
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 48-63 p.
Abstract
This work is aimed at studying the rheological properties and processes of structure formation in highly concentrated mineral suspensions modified with a complex organic and mineral additive based on a fluoroglu-cinifurfural oligomer and nanodiamond silicon dioxide particles.
Methods. The distribution of silicon dioxide particles and their modal size in additives were determined by laser light diffraction on the Mastersizer 3000 device and by dynamic light scattering on the Microtrac S3500 device. The rheological properties of the suspensions were determined using a coaxial cylindrical rotary viscometer of the gearless type “Rheotest-2.1”. The setting time and structure formation of the cement dough were evaluated on a Vika device. The plastic strength of the cement dough was determined using a conical Rebinder plastometer. The compressive strength of cement stone was determined using an automatic hydraulic press “PGM-100MG4”.
Conclusions. It has been established that a complex organic and mineral additive reduces the limiting dynamic shear stresses of mineral mixtures, reduces the plastic strength of mixtures in the initial period and shortens the setting time, providing a balance between deceleration and strength development due to the directional formation of consolidated supramolecular calcium silicate structures that structure the cement matrix. It was found that sili-con dioxide nanoparticles, which are part of a complex organic and mineral additive, do not affect the rheological properties of the system in the initial period, unlike Aerosil particles, which increase the limiting dynamic shear stress of the mixture, due to the high particle dispersion.
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Effective methods of concentration and purification of omega-3 polyunsaturated fatty acids: a systematic review and prospects

https://doi.org/10.58224/2619-0575-2024-7-4-64-86
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 64 – 86 p.
Abstract
The article is devoted to methods of concentrating and purifying omega-3 polyunsaturated fatty acids (PUFAs). The text discusses methods such as transesterification, urea complexation, chromatographic methods, low-temperature crystallization, supercritical fluid extraction, molecular distillation, and iodolactonization.
The aim of the research is to systematize literature data to identify the most effective methods for obtaining pu-rified, concentrated omega-3 PUFAs. The methods include transesterification for converting triglycerides into ethyl esters, urea complexation for separating fatty acids, chromatographic methods for high product purity, low-temperature crystallization for simplicity and cost-effectiveness, supercritical fluid extraction for environmental cleanliness and efficiency, molecular distillation for high selectivity, and iodolactonization for prospective separa-tion of omega-3 acids.
The article discusses the advantages and disadvantages of methods for concentrating omega-3 PUFAs. It also considers the prospects for developing effective and economical methods of enriching omega-3 fatty acids to re-duce costs and meet future demand for highly purified products.
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Study of temperature and salinity effect on encapsulated surfactants ability to alter wettability and decrease interfacial tension

https://doi.org/10.58224/2619-0575-2024-7-4-87-103
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 87-103 p.
Abstract
In recent decades, the task of increasing the oil recovery factor from productive formations has not lost its relevance. Today, there is a rapidly growing interest in the use of chemical methods to increase oil recovery to enhance production, in particular, using surfactants. To overcome the problem of high adsorption, which prevents the widespread introduction of surfactant flooding in carbonate formations, it is proposed to use the technology of encapsulating surfactants in a solid shell. Thus, the active substance can cover a large part of the reservoir, and therefore more oil can be extracted by injecting surfactants. In this work, the influence of typical reservoir conditions (high temperature and salinity) on the main properties of the dispersions of encapsulated surfactants, namely, a decrease in interfacial tension and a change in wettability, was studied. It is shown that the application of the encapsulation method preserves the necessary properties of surfactants, at which low interfacial tension is observed, and the surface of the carbonate rock becomes more hydrophilic.
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The effect of antioxidants on the survival of yeast cells under the action of X-ray irradiation

https://doi.org/10.58224/2619-0575-2024-7-4-104-117
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 104-117 p.
Abstract
Objectives: Saccharomyces yeast is one of the most studied species for the study of eukaryotic cells. The effect of ionizing radiation on living organisms is studied in radiobiology, the main task of which is to identify the laws of the biological reaction of the body to radiation. This will help to develop methods for monitoring radiation reactions and means of protection against radiation. There are unresolved problems in radiobiology, one of which is radiosensitivity. To study radiation sensitivity, the yeast strain Saccharomyces cerevisiae T-985 was used, as well as rutin, a biologically active substance, a flavonoid with antioxidant and other beneficial properties.
Methods. The spectrophotometric method is based on the use of the free stable radical 2,2-diphenyl-1-picrylhydrosyl (DPPH). After the end of cultivation, aliquots of the yeast suspension were taken from the flasks and transferred into glass flasks with a volume of 1 mL for subsequent irradiation at the Model- KALAN 4 X-ray unit in the IMSEN-IFC of the D.I. Mendeleev Russian Chemical University at an absorbed dose rate of 3 Gy/s according to the Fricke dosimeter [10, 11]. To detect the effects of ionizing radiation and compare the results with the control sample, optical density measurement and microscopy were used.
Results. Rutin may have a protective effect on yeast cells after X-ray irradiation. It has been shown in studies that rutin can reduce oxidative stress and DNA damage caused by irradiation. This may be due to its ability to neu-tralize free radicals and repair damaged molecules. Comparing the results of 0.05mM rutin and rutin and hydrogen peroxide systems, it can be noted that the active form of oxygen negatively affects the survival rate of yeast cells. ionol has a favorable effect on survival and repair processes in yeast cells. The addition of hydrogen peroxide significantly decreases the survival rate of cells immediately after irradiation, but promotes the reparative pro-cesses. As a result of experiments, addition of Rutin with the concentration of 5·10-4 mol/L potentially increases the number of viable cells capable of colony formation than addition of Rutin with the concentration of 5·10-5 mol/L. CFU of S. cerevisiae species with the addition of rutin at different concentrations decreases many times in relation to the control after 3 days at a dose of 400 Gy and 800 Gy of X-ray irradiation.
Conclusions. - With increasing irradiation dose the concentration of rutin decreases, which suggests that it is consumed. The radiation chemical yield of rutin consumption was determined: G (0-400)=0.04 molecules/100 eV; G(400-2000)=0.10 molecules/100 eV.
- The inhibition effect in the reaction with DPPH of rutin solutions without irradiation and one day after irradi-ation was determined. The numerical values are in the range from 67% to 86%, which is more than 50%, which means that rutin has high antiradical properties after irradiation.
- Percentage of dead cells in suspension when rutin was added is less compared to the percentage of dead cells in suspension without rutin at the same absorbed doses.
- In tubes with the addition of rutin of different concentrations, which received a dose of 800 Gy, a day after ir-radiation, there is a significant decrease in the percentage of dead cells compared to the same data obtained with-out the addition of rutin. This can be interpreted as active repair processes.
- At addition of rutin with concentration 5·10-4 mol/l the percentage of dead cells is less than at addition of rutin with concentration 5·10-5 mol/l.
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Removal of harmful gases from the air stream using carbon sorbents based on plant waste of the Republic of the Union of Myanmar

https://doi.org/10.58224/2619-0575-2024-7-4-118-130
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 118-130 p.
Abstract
Objectives: in this work, we evaluated the ability of the adsorbent of gas-vapor activated carbon obtained from the shells of macadamia nuts of one of the enterprises in Myanmar as an agent of the recovery technology using the example of the extraction of n-butanol vapors from their mixtures with air (AVM).
Methods. The object of the study was pre-dried macadamia nuts, which were crushed, heat treated at 650-700°C for 60 minutes in pyrolysis, followed by water vapor at a temperature rise of 15 °C/min without thermal ex-posure, the specific consumption of water vapor was 5 g per 1 g of the resulting activated carbon. The obtained sorbents were analyzed for the sorption properties of C6H6, CCL4 and H2O vapour. Their total volume was deter-mined, their porous structure was estimated by the volume of pores of various sizes, the absorption of iodine and methylene blue from aqueous solutions. Their ability to remove harmful gases during adsorption of n-butanol at different relative pressures was characterized and their adsorption kinetics and isotherms were studied.
Results. It is shown that the values of the coefficients obtained from the kinetic equation a = A(1-e-B·τ) of the obtained active carbons are preliminarily performed in their pores with butanol. According to the values of A and B, these sorbents are actively absorbed by harmful gases from the vapor-air mixture. For comparison, the article presents the quality indicators of active carbons of the CS (coconut shell) and PS (plum seed) brand made frоm a number of agricultural wastes of Myanmar.
Conclusions. The studies allow us to state quite satisfactory absorption properties of the obtained new activated carbon from the shell of macadamia nuts, in the studied process of extracting n-butanol vapors from their mixtures with air, which indicates the probable competitiveness of this adsorbent in solving the problems of purification from vapors of organic substances of emissions of high concentrations, provided that its production is organized in the conditions of Myanmar.
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A set of possible approximative methods for effectively accounting for the contribution of Coulomb integrals to dramatically accelerate the calculations of DFT giant biomolecules: reduction to fast-computable short-range two-center splines plus FMM long-range Coulomb

https://doi.org/10.58224/2619-0575-2024-7-3-49-63
 49-63 p.
Abstract
A set of approximative methods is proposed to radically accelerate the calculation of the contribution of Coulomb integrals in the calculations of DFT giant biomolecules - the limiting stage of such relevant but extremely resource-intensive calculations, including calculations of thousands of docking complexes of thousands of atoms. The proposed complex includes, through a quick and accurate approximation of the contribution of a huge number of 4-center Coulomb integrals through a linear combination of 3-center integrals, and then through a combination of 2-center integrals. The non-multi-complete short-range components of these 2-center integrals are very quickly considered pre-prepared splines from the center-to-center distances. The remaining long-range multipole contributions are quickly calculated for giant molecules in the FMM style (splitting a huge space into regions and subdomains, was originally developed for the dynamics of galaxies). Calculations are saved as much as possible everywhere due to pre-selected combinations of integrals. All two-center components (including the approximation of two-center overlaps of basic functions through linear combinations of single-center auxiliary density functions) are quickly calculated due to splines from internuclear distances from a specially prepared database. For new bases, the database is easily and quickly replenished by decomposing the new basis into a set of universal ex-ponents and a database with them.
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Electrochemical production of manganese dioxide from sulfuric acid electrolyte

https://doi.org/10.58224/2619-0575-2024-7-3-64-77
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 64-77 p.
Abstract
This paper investigates the process of electrochemical production of manganese dioxide from a 10% sulfuric acid electrolyte leaching the active mass of spent manganese-zinc chemical power sources. The relevance of the topic is due to the wide application of MnO2 in modern industry and the need to develop efficient methods for obtaining it from secondary raw materials. The aim of the study was to examine the influence of electrolyte temperature and ultrasonic treatment on the properties and sizes of the obtained manganese dioxide particles. The experimental methodology included electrolysis in a three-electrode cell with temperature variation from 30°C to 90°C and current density of 3-5 A/dm2. Ultrasonic treatment of the electrolyte was carried out at a frequency of 20 kHz. The obtained MnO2 samples were studied using scanning electron microscopy and X-ray energy-dispersive analysis. The results showed that increasing the electrolyte temperature leads to an increase in the size of manganese dioxide particles from 0.2 to 5-10 microns. The introduction of ultrasound allows obtaining highly dispersed MnO2 with crystallite sizes of less than 50 nm. The maximum current yield (92%) is achieved at 60°C and a current density of 5 A/dm2. The practical significance of the work is associated with the possibility of obtaining nanostructured manganese dioxide with improved electrochemical characteristics from spent raw materials. Further research will be aimed at optimizing the parameters of electrolysis and ultrasonic treatment to control the morphology and properties of MnO2.
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Kinetics and mechanism of adsorption of methylene blue dye by crushed sunflower biomass

https://doi.org/10.58224/2619-0575-2024-7-3-78-92
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 78 – 92 p.
Abstract
Objectives: to study the kinetics and mechanism of dye adsorption by cellulose raw materials. Methods. As a sorbent, waste from crop production was used – ground sunflower stalks, initial and modified with 10% NaOH alkali, with a particle size from 1 to 2 mm. Methylene blue dye was selected as an adsorbate by preliminary tests. Adsorption isotherms were constructed to determine the maximum sorption capacity. Kinetic models of sorption of the pseudo-first and pseudo-second order are constructed. In order to determine the mechanism of the process, thermodynamic constants were determined: sorption energy (E), Gibbs energy (ΔG) and Bio coefficient (Bi).
Results. The maximum sorption capacity of the crushed biomass of sunflower stalks in relation to the dye is 0.52 mmol/g for the alkali-modified material, which is 48% higher than the initial content (0.35 mmol/g). Thus, the SP(NaOH) material showed improved sorption properties, and it was selected for further kinetic studies. The sorp-tion energy is 5.82 kJ/mol, which may indicate physical adsorption. The Gibbs energy is -6.3742 kJ/mol, less than zero, which indicates the spontaneity of this process. The adsorption equilibrium for the MG dye occurs after 120 minutes, the kinetic curve has a smooth character. The Bio coefficient is 1.812, therefore, the adsorption process is limited by mixed diffusion.
Conclusions. The analysis of the data obtained made it possible to determine the Bio coefficient reflecting the course of MG adsorption by a mixed–diffusion mechanism over the entire time range of adsorption. This indicates the complex character of the MG adsorption process and confirms the importance of taking into account various factors influencing this process when developing methods for cleaning aquatic environments from organic pollu-tants.
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