ННІ “Український державний хіміко-технологічний університет” (ННІ УДХТУ)

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ENG: Ukrainian State University of Chemical Technology (USUCT)

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Application of Physical and Quantum-Chemical Characteristics of Epoxy-Containing Diluents for Wear-Resistant Epoxy Compositions
(MDPI, Basel, Switzerland, 2025) Kulikov, Andrii; Sukhyy, Kostyantyn M.; Yeromin, Oleksandr O.; Fedak, Marcel; Prokopenko, Olena M.; Sukha, Iryna V.; Poloz, Oleksii; Mikats, Oleh; Hrebik, Tomas; Kulikova, Olha; Lopusniak, Martin
ENG: Low-viscosity epoxy-containing diluents are used to reduce the initial viscosity of highly filled, wear-resistant epoxy systems and to improve filler wetting and dispersion. This study determined physical parameters by an atomic-increment approach and electronic descriptors using the Parametric Method 3 (PM3) semi-empirical method. Clear relationships were established between the effective molar cohesion energy and the solubility parameter with van der Waals volume. Linear dependencies were also obtained between the diluent surface tension and spreading coefficients on model high-hardness fillers, including silicon carbide, boron carbide, and normal corundum. The activity of epoxy diluents depends on the lowest unoccupied molecular orbital energy. These diluents influence processing and the final physical and mechanical properties of composites, making their selection critical for strength, hardness, and wear resistance. Computational analysis enables prediction of diluent behavior, reducing experimental time and cost. Integrating physical and quantum-chemical data into epoxy diluent design accelerates the search for optimal components and improves production of durable, high-performance epoxy composites.
An Assessment Method for the Control Systems Quality
(Одеський національний технологічний університет, 2025) Manko, Hennadii I.
ENG: Possibilities and methods of applying the concept of uncertainty in order to assess the quality of control are investigated. An analysis of the approaches currently used for uncertainty assessment is carried out. The use of the informational approach for this purpose is substantiated. It is proposed to use informational uncertainty as a criterion for the quality of control tools. For this, the amount of negative information (misinformation) caused by the imperfection of management methods and devices is calculated. The method of estimating the amount of misinformation is based on Bongard's concept of uncertainty. Misinformation is considered as Bongard's negative useful information. The amount of misinformation is the difference between the Shannon entropy and the Bongard’s uncertainty and is used as a criterion for absolute information uncertainty. The criterion of relative information uncertainty is also proposed as the ratio of the amount of misinformation introduced by the control tool to the maximum possible value of misinformation. The maximum value is the amount of misinformation at zero Shannon entropy. Mathematical expressions for calculating the absolute and relative uncertainty of control systems are given.Formulas for calculating deterministic analogs of Shannon's entropy and Bongard's uncertainty are proposed to assess the quality of control tools that are investigated by non-statistical methods. Appropriate expressions for calculating criteria of absolute and relative uncertainty based on transient processes of control systems are derived. The practical use of the proposed method is shown. To demonstrate the use of the criterion of information uncertainty, simulation of the PID controller was carried out using Scilab/Xcos tools. The vectors of input and output values obtained as a result of modeling were processed using the formulas introduced in this article. The criterion of relative information uncertainty was applied to compare the quality of PID controllers that were discretized by different methods.
Assessment of the Efficiency of Hot Helium Tank Pressurization Systems for Oxygen-Propelled Rocket Engines
(Publishing House “Akademperiodyka”, Kyiv, 2025) Sukhyi, Kostiantyn M.; Voit, S. M.; Mitikov, Yurii O.; Spirkin, S. V.; Sukha, Iryna V.
ENG: For the first time, a study of the design has been conducted, and a detailed weight summary of the hot helium pressurization system for an oxidizer tank of the first stage of a launch vehicle (LV) has been presented; the propulsion system of this LV uses boiling oxygen — RG-1 as propellants. The oxidizing generator gas was considered as the heat exchanger heat carrier. The weight of this system was also evaluated for an alternative common heat carrier — reduced generator gas. A good correlation was shown between the obtained results and known data from other pressurization systems. The efficiency of hot helium pressurization systems is demonstrated in the case of multiple reuses of the first stage of an LV. It is also reasonable to use it for the dual activation of the liquid rocket engine (LRE) of the second stage of an LV. In these cases, arising issues are solved using well-established, proven solutions. However, an analysis of technical literature shows that alternative solutions have not been thoroughly studied. In other cases, considering the high cost, structural complexity, actual low reliability, and lack of weight advantages, the use of hot helium pressurization systems (PS) is hardly justified. This primarily concerns LREs with afterburning of generator gas, where oxidizing gas is used as the coolant in the heat exchanger. It is also noted that it is necessary to provide helium reserves on board of the LV and to introduce a gas pressure regulation system in the tank. This is due to the large variations in pressurization path resistance and helium temperatures after the heat exchanger at the design stage. The result is an increase in the calculated gas pressure in the tank, leading to an additional weight increase of 5–8%. It is shown that helium reserves can be easily adjusted based on the results of the first flight tests, whereas reducing the thickness of the tank walls and the diameter of the hot pressurization pipelines with thermal compensators is extremely problematic.
Atomic Emission Determination of Cesium in Table Salt and Brines
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Yurchenko, O.I.; Chernozhuk, T.V.; Baklanov, A.N.; Nikolenko, M.V.; Cherginets, V.L.; Rebrov, A.L.
ENG: Atomic emission spectrometry has been shown to be one of the most effective methods for determining cesium content in table salt and brines after preconcentration by coprecipitation. The most efficient collectors for cesium coprecipitation are ferrocyanides with the general formula MeII 2Fe(CN)6 (Me=Cu, Co, Ni). It was found that using copper ferrocyanide enables the extraction of up to 92% of cesium from solution. However, in water, brines, and salt solutions, cesium often exists in forms that cannot be coprecipitated (in more than 50% of cases). Therefore, organic cesium compounds (humic and fulvic acids) must be destroyed. The effect of ultrasound on highly mineralized waters, brines, and salt solutions to convert cesium compounds into coprecipitable forms was studied. It was established that the main factors contributing to the intensifying effect of ultrasound are the occurrence of sonochemical reactions, as well as the mixing and dispersing actions of ultrasound. An express method for determining cesium in table salt and brines was developed, involving the destruction of organic impurities and the coprecipitation of cesium with Cu2Fe(CN)6 under ultrasonic intensification. The detection limit for cesium is 2⋅10–8 wt.%.
Bioactive Coatings on Ti–Zr–Nb Alloy: Synthesis, Characterization and Implantology Potential
(MDPI AG, Basel, Switzerland, 2026) Kovalenko, Kseniia; Sukhyi, Kostiantyn M.; Fedak, Marcel; Rimar, Miroslav; Kalinichenko, Oleh O.; Yeromin, Oleksandr O.; Shmychkova, Olesia B.; Kulikov, Andrii; Kovalyov, Stanislav V.; Sukhyi, Mykhailo
ENG: This research reports on the properties of oxide-ceramic coatings produced by plasma electrolytic oxidation in novel electrolyte solutions for implantology applications. A series of bioactive calcium-phosphate coatings was synthesized on medical-grade Ti-13Zr-13Nb alloy using the plasma electrolytic oxidation (PEO) method. Novel electrolytes enriched with calcium and phosphorus were developed, enabling the formation of coatings with tailored physicochemical and structural characteristics. A correlation was established between the electrolyte composition and the phase composition, thickness, morphology, porosity, and microhardness of the resulting coatings. The optimum coatings exhibited a Ca/P ratio close to that of natural human bone tissue, homogeneity, a well-developed porous surface topography, and controlled resorption behavior. For the first time, a mechanism of calcium-phosphate coating resorption in a biologically active environment has been proposed. It involves partial dissolution, the formation of apatite-like surface structures, and the subsequent controlled release of Ca and P ions. In vitro testing in simulated body fluid indicated the potential bioactivity of the synthesized coatings. The proposed calcium-phosphate coatings may be considered promising candidates for future implant surface modification. The results obtained are significant for the development of advanced orthopedic and dental implants, including those fabricated using additive manufacturing technologies.
A Competency-Based Approach to Developing Students' Listening and Reading Skills While Foreign Language Learning
(Bulletin of Science and Education, 2025) Anataichuk, Inna M.; Zabrudska, Lіudmyla М.; Sazonova, Viktoriia S.
ENG: The competence-based approach to foreign language learning involves not only the development of linguistic knowledge (vocabulary, grammar, phonetics) but also the ability to use this knowledge effectively in real-life situations. This means that the primary focus is on the practical aspect of language proficiency, which ensures not only the acquisition of theoretical material but also the development of language skills, intercultural communication abilities, critical thinking, teamwork, and problem-solving competencies. A particular emphasis is placed on listening and reading skills, as they serve as the foundation for receiving, processing, and analyzing information and for the further development of other types of language activities such as speaking and writing.The aim of this article is to define the main principles of the competence-based approach to developing students’ listening and reading skills and to identify the key challenges associated with its implementation in the educational process. The study analyzes both didactic and psychological aspects of language teaching and explores effective strategies and methodologies that enhance active student participation. This approach transforms learning from passive knowledge absorption into an active process where students become full participants in communication and knowledge acquisition.The competence-based approach is also closely linked to increased student motivation. Learners see the practical benefits of studying the language, as the acquired knowledge and skills enable them to navigate in a foreign-language environment, comprehend authentic texts, and participate in intercultural dialogue. The use of interactive teaching methods, authentic materials, and situational modeling creates favorable conditions for the effective development of listening and reading skills, as well as for the formation of key competencies required in modern society.
Control of Drum Shear Electric Drive Using Self-Learning Artificial Neural Networks
(MDPI, Basel, Switzerland, 2025) Batyrbek, Alibek; Kuznetsov, Valeriy; Kuznetsov, Vitalii V.; Rojek, Artur; Kovalenko, Viktor; Tkalenko, Oleksandr; Tytiuk, Valerii; Krasovskyi, Pavlo
ENG: The objective of this work was to study the possibility of upgrading the control system of the drum shear mechanism by using neural network PI controllers to improve the efficiency of the sheet-metal cutting process. The developed detailed model of the mechanism, including a dual DC electric drive with three subordinate control loops for the voltage of the thyristor converter, current and speed of the motors, a 6-mass kinematic system with viscoelastic connections as well as a model of the metal cutting process, made it possible to uncover that the interaction of electric drives with the mechanical part leads to significant speed fluctuations during the cutting process, which worsens the quality of the sheet-metal edge. A modified system of current and speed controllers with built-in three-layer fitting neural networks as nonlinear components of proportional-integral channels is proposed. An algorithm for the fast learning of neural controllers using the gradient descent method in each cycle of calculating the controller signal is also proposed. The developed neuro-regulators make it possible to reduce the amplitude of speed fluctuations during the cutting process by four times, ensuring the effective damping of oscillations and reducing the duration of transient processes to 0.1 s.
Crystal Structure of the Mixed-Ligand Complex of Co(II) with Succinic Acid and Pyridine
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Trunova, O. K.; Zheleznova, L. I.; Dyakonenko, V. V.; Sliusarchuk, L. I.; Shtokvysh, O. I.; Berzenina, Oksana V.
ENG: A new mixed-ligand complex {[CoCHO)⋅2Ðó]⋅2H2O}n was synthesized via the interaction of equimolar amounts of cobalt nitrate and sodium succinate in the presence of pyridine at pH 5.5–6.0. The complex was investigated by X-ray structure analysis, elemental analysis, UV/VIS and IR spectroscopies, and differential thermal analysis. The complex is a one-dimensional coordination polymer and crystallizes in the orthorhombic space group Pbca with unit cell parameters a=11.8945 Å , b=8.9064 Å , c=15.1116 Å , α=β=γ=90 Celsius degrees. The atom of cobalt has a slightly distorted octahedral N2O4 environment and forms Co–N bonds with two molecules of pyridine and Co–O bonds with the carboxyl groups of two symmetric succinic acid molecules. The coordination number Co(II) is supplemented up to 6 by two water molecules, which are located in the axial plane of the coordination polyhedron. Due to the monodentate coordination of two symmetrically independent carboxylate oxygen atoms of one succinic acid molecule, one-dimensional coordination polymer chains are formed. Polymer chains in the crystal are united by intermolecular hydrogen bonds, which leads to the formation of layers packed in the crystal parallel to the (001) plane. Hirschfeld surface analysis and two- dimensional fingerprint plots were used to analyze the intermolecular interactions present in the crystal.
Des-Assisted Electrodeposition and Characterization of an Electrocatalyst for Enhanced Urea Oxidation in Green Hydrogen Production
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Protsenko, Vyacheslav S.; Shaiderov, D. A.; Sukhatskyi, O. D.; Butyrina, Tetiana E.; Korniy, S. A.; Danilov, F. I.
ENG: An important task of modern materials science is the development of highly efficient electrocatalysts for green hydrogen production. Specifically, this involves the urea oxidation reaction (UOR), which is an energetically advantageous and attractive alternative to the anodic oxygen evolution reaction, coupled with hydrogen evolution at the cathode. In this work, we present for the first time the use of systems based on a new generation of environmentally friendly room-temperature ionic liquids – deep eutectic solvents (DESs) – for the electrodeposition of electrocatalysts for UOR. The electrochemical performance of electrodeposited nanocomposite Ni–CeO2 electrocatalysts was evaluated in alkaline solution, showing an appreciable reduction in the anodic potential of UOR compared to oxygen evolution, reaching up to approximately 0.2 V at a current density of 0.1 mA cm–2. The obtained results are significant for the development of electrochemical synthesis methods for electrocatalysts used in green renewable energy.
Design, Fabrication and Functional Properties of Titanium Suboxide-Based Composites With Low Noble Metal Content for Electrocatalytic Applications
(Journal of Electrochemical Science and Engineering, 2025) Knysh, Valentina О.; Zhemela, Heorhii; Shmychkova, Olesia B.; Luk'yanenko, Tatiana V.; Velichenko, Oleksandr В.
ENG: Fabrication, design and investigation of functional properties of composite materials based on titanium suboxides with low noble metal content for use in electrocatalysis has been investigated. The study particularly focuses on electrode coatings derived from titanium dioxide modified with platinum and palladium. The structural, electrocatalytic, and corrosion-resistant properties of these materials were systematically investigated. It was demonstrated that thermal treatment significantly enhances the catalytic efficiency of the coatings by reducing the oxygen evolution overpotential and improving the efficiency of hypochlorite synthesis. Optimal thermal treatment conditions (500 °C, 3 hours) were identi-fied, resulting in increased stability of the anodes containing Pt and Pd layers, as evidenced by a service life of 176 hours. The study highlights the potential of these composites for applications in oxygen evolution reactions and hypochlorite synthesis, owing to their high stability, selectivity, and cost-effectiveness.
Determination of the Efficiency and Selectivity of Anodic Dissolution of a Heat-Resistant Rhenium-Containing Superalloy in Chloride-Containing Media With Sulfuric or Methanesulfonic Acids
(Eastern-European Journal of Enterprise Technologies, 2025) Kotok, Valerii Е.; Sknar, Yuri Е.; Butyrina, Tetyana Е.; Sknar, Irina V.; Sukha, Irina V.; Demchyshyna, Oksana
ENG: Тhe object of this study is the elec-trochemical anodic dissolution of a heat-resistant nickel-based superalloy containing rhenium and other alloying elements in acidic electrolytes containing sodium chloride. The investi-gated alloy was obtained from scrap of high-temperature equipment. The anodic dissolution of the superalloy was studied in two acidic media: sulfuric and methanesulfonic acids. A comparative analysis of cyclic voltammetry and galvanostatic experiments was carried out. In sulfuric acid electrolyte, anodic processes proceed more vigorously, as indicated by higher cur-rent densities. However, this method records not only the dissolution currents of metals but also side processes such as anodic oxygen evolution and reoxidation of dissolved ions. Under galvanostatic conditions, which allow direct determination of alloy mass loss, it was shown that methanesulfonic acid with sodium chloride pro-vides a higher dissolution rate despite the medium's lower conductivity. This effect is explained by the higher solubility and stability of the methane-sulfonates of the alloying components (Cr, Al, Nb, Ta, Re), which reduce the tendency of the surface to repassivate. In the H2SO4 + NaCl medium, dissolution proceeds more uniformly but at lower mass efficiency, attributed to the formation of poorly soluble sulfates. In the methanesulfonate electrolyte, within the current density range of 1.5–2.5 A•dm-2, the ratios of Ni, Cr, Co, W, and Re were closest to those in the original alloy, while rhenium was detected in solution, unlike in the sulfuric medium. The obtained results can be applied to optimize the initial stage of superalloy recycling and to develop electrochemical technologies for the recovery of strategically important metals from industrial waste.
Determination of the Electrochemical Dissolution Feasibility of a Superalloy Used in Turbine Components in Alkaline Solutions With Additives
(Eastern-European Journal of Enterprise Technologies, 2025) Kotok, Valerii Е.; Sknar, Yuri Е.; Butyrina, Tetyana Е.; Sknar, Irina V.; Demchyshyna, Oksana; Chasova, Ella
ENG: The object of this study was an electro-chemical anodic dissolution of a heat-re-sistant nickel-based superalloy (≈62 wt.%),recovered from destroyed components of spe-cial-purpose equipment, which contains valu-able metals such as Re (≈4 wt.%), Co, W, Mo, Ta, Nb, and others. The research addressed the problem of the lack of an effective elec-trochemical method for selectively extract-ing these components, particularly rhenium and other valuable elements, from such an alloy in alkaline media. The anodic behav-ior of the alloy was experimentally studied in 0.5 M NaOH in the presence of various com-plexing and activating additives (NaCl, cit-ric acid, EDTA salt, and Na2H2P2O7). It was shown that none of the additives provided a significant acceleration of anodic dissolu-tion. This was demonstrated by the fact that the increase in the average specific charge calculated for five cyclic voltammetry scans that contributed to alloy dissolution did not exceed 8%. In other cases, the values were sig-nificantly lower than in the base solution con-taining only alkali. It was established that the anodic dissolution process has a surface-selec-tive nature: Ni, Co, Cr, Re, and Al are leached into the electrolyte, while a residual surface layer enriched in W, Ta, Nb, and Mo forms, hindering further dissolution. X-ray fluores-cence analysis data confirmed changes in the chemical composition(Ni content decreased to ≈48 wt.%, W increased from ≈9to≈20wt.% on the surface). Theoretical justification of the results is provided, based on the physico-chemical properties of compounds that may form during anodic dissolution in the pres-ence of additives. The absence of an activating effect from the additives suggests the need for further studies on pure NaOH. The obtained data are of practical importance for the selec-tive separation of superalloy elements before further processing.
Development of Polymer Composite Materials for Friction Elements of Conveyor Equipment
(Technology Audit and Production Reserves, 2025) Sytar, Volodymyr І.; Kozyrko, Dmytro; Kabat, Oleh S.; Nazarenko, Andriy
ENG: The object of the study is materials with enhanced tribological properties intended for the friction components of conveyor equip-ment. One of the most critical issues is ensuring the wear resistance of friction units in conveyor systems, particularly under dry friction conditions. A promising solution involves the use of tribotechnical polymer composite materials (PCMs) based on aromatic polyamide.The research involved the use of modified graphite-containing systems based on aromatic polyamides filled with graphites of various dispersities and at different mass concentrations.Polymer composites were obtained based on aromatic polyamide modified with organosilicon fluid and filled with graphites differ-ing in nature and morphology. A correlation was established between the antifriction properties of the polymer compositions and both the filler content and graphite grade.Under dry friction conditions, the enhancement of antifriction properties is achieved by incorporating graphite into the aromatic polyamide in an effective concentration of 15–20%, at which a stable antifriction film forms on the counterbody surface, acting as a solid lubricant. In this case, the coefficient of friction and the linear wear rate of the material remain low, 0.1 to 0.15 and 0.5 to 1 × 10–⁹ m/m, respectively. A notable observation is that during friction, the graphite material wears away while the metal remains virtually unaffected. It was found that an excessive filler content (> 20%) leads to brittleness of the composite, which is a critical design limitation.As a result, the developed material can be effectively used for friction components operating under dry, lubrication-free conditions. This justifies its high utility and environmental benefits, as it eliminates the need for lubricants and their disposal. Compared to tradi-tional materials such as bronze, the proposed composites offer distinct advantages.
Development of Rare Earth Metal-Modified Heat-Resistant Coatings for Gas Turbine Blades
(Ukrainian State University of Chemical Technology, Dnipro, 2024) Yefanov, V. S.; Gnatenko, M. O.; Laptieva, H. M.; Basov, Y. F.; Sukhyy, Kostyantyn M.; Kovalyov, Stanislav V.; Popov, S. M.
ENG: This paper presents an investigation into the influence of Y-La and Y-Hf-La modifiers on the structure and properties of Ni-Cr-Al consumable cathodes used for heat-resistant coatings on turbine blades via the arc-ion plating method. The study shows that the introduction of these modifiers positively affects the structure formation process of the consumable cathodes. The modifiers contribute to a higher degree of microstructural homogeneity in the cathodes, achieved through the formation of nanosized stabilizing phases between the alloying elements and the rare earth metal groups. This study experimentally confirms that Ni-Cr-Al coatings produced with the Y-La and Y-Hf-La modified cathodes outperform traditional Y-only modified coatings in oxidation tests. Structural analysis of the coatings reveals that samples with Y-Hf-La exhibit greater homogeneity and fewer defects, which is particularly important when depositing coatings with large thicknesses (over 40 µm). It was found that the introduction of the Y-Hf-La complex enables the application of coatings up to 90 µm thick by forming a less defective structure. Additionally, it has been established that Y-Hf-La modification enhances the adhesion of the coating to the substrate and allows for maximum uniformity in the distribution of alloying elements throughout the entire thickness of the applied coating.
Dialkyl-N-Alkoxy-N-(4-Toluenesulfonyl) Phosphoramidates: Synthesis and Structure
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Shtamburg Vasiliy G.; Klots E. A.; Shtamburg V. V.; Anishchenko A. A.; Shishkina S. V.; Kravchenko S. V.; Mazepa A. V.
ENG: This study investigates the reaction between N-alkoxy-N-chloro-4-toluenesulfonamides and N-chloro-N-(methoxy)methanesulfonamide with trialkyl phosphites, resulting in the formation of dialkyl N-alkoxy-N-(4-toluenesulfonyl)phosphoroamidates and dialkyl N-methoxy-N-methanesulfonylphosphoroamidates, respectively. The resulting dialkyl Nalkoxy-N-(4-toluenesulfonyl)phosphoramidates and N-alkoxy-Nmethanesulfonylphosphoramidates are identified as products of nucleophilic substitution at the amide nitrogen atom. The structures of these compounds have been confirmed by H, P and C NMR spectroscopy, mass spectrometry, and an XRD study. The XRD study of dimethyl N-methoxy-N-(4-toluenesulfonyl)phosphoroamidate and dimethyl N-ethoxy-N-(4-toluenesulfonyl)-phosphoroamidate reveals a pyramidal configuration at the amide nitrogen atom, along with the shortening of the N–O(Alk) bond and the elongation of the N–P and N–S bonds. In the asymmetric part of the unit cell, dimethyl N-ethoxy-N-(4-toluenesulfonyl)phosphoramidate exists in the form of two independent molecules that differ in the degree of pyramidality of the nitrogen atom and the lengths of its bonds.
Digital Marketing Ecosystem as an Element of Enterprise Strategy
(ННІ “Український державний хіміко-технологічний університет“, 2025) Avdiienko, Vladyslav А.; Chernysheva, Olena М.
ENG: The article is devoted to the formation of the digital marketing ecosystem and determining the influence of its components in the hierarchy of the enterprise strategy. The significant role of digital marketing in the formation of the strategy of a modern enterprise is shown. It is established that digital marketing is deeply integrated into the overall strategy of the enterprise, penetrating the key areas of the promotion complex – advertising, direct marketing, PR, personal sales, sales promotion, event organization. Elements of the promotion strategy have been improved, which differ from traditional ones in that they are based on the digital marketing ecosystem, which makes it possible to adapt the enterprise strategy to the needs of consumers in the conditions of digital market transformation. The digital marketing ecosystem has been formed as a component of the promotion strategy in the hierarchy of enterprise strategies. The digital marketing ecosystem consists of closely interconnected elements: promotion channels (websites, social networks, mobile applications, chatbots), ways of interaction (advertising, PR, direct marketing, personal sales, sales promotion, events), content types (photos, videos, text messages that are combined into posts), devices for consuming content (smartphones, PCs, tablets, smart TVs, interactive panels and wearable gadgets). Close relationships have been established between these elements: devices affect the type of content, the type of content determines which promotion channels will be effective for its placement. Promotion channels, in turn, determine the format and frequency of use of certain interaction ways. They adapt the content to themselves, creating an appropriate narrative, call to action, visual style. The effective operation of this system ensures the implementation of the promotion strategy in the activities of modern enterprises. Visualization of the ecosystem makes it possible to present digital marketing as a holistic, coherent system. It has been proven that changing even one element can cause a radical transformation of the marketing mix and affect the higher strategies of the enterprise.
Effect of Clearance on Residual Stress and Quality in Rolled Tube-Tubesheet Connections
(Вісник Приазовського Державного Технічного Університету, 2025) Stovpnyk, Oleksandr V.; Kabat, Oleh S.; Ved’, Viktor V.
ENG: The quality of the tube-to-tubesheet joint is a critical factor determining the reliability and durability of heat exchangers and various types of industrial equipment operating under demanding conditions. This article examines the influence of the clearance between the tube and the tubesheet hole on the magnitude of residual stresses in the joint following the tube rolling process. The experimental component of the study involved precise measurements of actual clearances using specialized tools, the calculation of residual stresses through the mechanical stress relief method, and a comprehensive statistical analysis of the collected data to ensure accuracy and consistency. The findings revealed that the actual clear-ance typically exceeds the nominal value specified in design standards, and an increase in this clearance directly corre-lates with a rise in residual stresses within the joint. Notably, the highest stress levels were observed at clearances of 0.40 mm and greater, which may lead to localized plastic deformation, compromising the structural integrity and reducing the fatigue strength of the joint over time. Based on the analysis, the optimal clearance range was determined to be between 0.10 mm and 0.30 mm, as it strikes a balance between ensuring joint reliability and maintaining acceptable stress levels, thus minimizing the risk of premature failure. To validate the reliability of the experimental results, advanced statistical methods were employed, including the calculation of standard deviation to assess data variability and the application of Student's t-test to evaluate the significance of the observed trends. These calculations confirmed a statistically significant relationship between clearance size and residual stress levels, with particularly pronounced effects observed in joints involving small-diameter tubes, where tolerances are more critical. The outcomes of this research have practical impli-cations for the design and manufacturing of shell-and-tube heat exchangers, offering a pathway to optimize joint param-eters, enhance operational performance, and extend service life. Additionally, the study provides detailed practical rec-ommendations for quality control, including precise methods for measuring clearances with highaccuracy and evaluating residual stresses during production and maintenance processes.
Effect of Manganese Concentration and Calcination Temperature on Photochemical Properties of TiOF2/MnO(OH)
(MDPI AG, Basel, Switzerland, 2025) Sofronov, Dmytro; Frolova, Liliya A.; Rucki, Miroslaw; Mateychenko, Pavel; Baranov, Vyacheslav
ENG: The heterostructures TiOF2/(0.5–5 wt.%)MnO(OH) attract attention as potential catalysts for pollutant removal from water. In this paper, a novel synthesis route was proposed through the precipitation of MnO(OH) particles out of an alkaline solution on the TiOF2 particles. The formation of manganese oxyhydroxide was confirmed by X-ray diffraction analysis. The presence of manganese in proportions up to 1 wt.% recalculated to MnO(OH) did not affect the morphology of TiOF2/MnO(OH) particles. Higher concentrations of Mn caused the appearance of mostly spherical particles of dimensions ca. 100 nm. The effect of calcination temperatures 300–600 °C on the structure and photocatalytic activity of the particles was analyzed. It was found that calcination of the powder formed TiO2 phase with mainly anatase structure as well as Mn3O4. After calcination at 600 °C, the appearance of fluorine was detected, indicating the formation of fluorinated titanium dioxide. For higher manganese concentrations, the fluorine proportion in F-TiO2 samples decreased. Increased Mn content in TiOF2/MnO(OH) significantly improved its photocatalytic activity, shortening the degradation time and increasing the degradation degree of methylene blue (MB). However, an increase in the calcination temperature decreased the degradation degree of MB. It was found that the optimal concentration of MnO(OH) was 5 wt.%.
Effect of Na+ vs. K+ Cations and Carbonate Presence on Urea Oxidation Reaction Coupled with Green Hydrogen Production in Alkaline Media: A Voltammetric and Electrochemical Impedance Spectroscopy Study
(Hydrogen, 2025) Protsenko, Vyacheslav S.; Shaiderov, Denys A.; Sukhatskyi, Oleksandr D.
ENG: This work reports the electrochemical behavior of a nickel hydroxide electrode, electrodeposited in a deep eutectic solvent (DES), in alkaline solutions of varying composition, aiming to elucidate the influence of the cation (Na+ vs. K+), urea, and carbonate ions on the mechanism and kinetics of anodic processes. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to analyze the electrochemical responses of electrode processes in alkaline water electrolysis systems. For the urea oxidation reaction (UOR), the frequency-dependent characteristics were thoroughly characterized, and the impedance response was simulated according to the Armstrong–Henderson equivalent circuit. It was found that the addition of urea significantly transforms the impedance structure, sharply reducing the polarization resistance and increasing the pseudo-capacitive component of the constant phase element at low frequencies, indicating activation of the slow steps of urea oxidation via a direct mechanism and the formation of an extended adsorptive surface. It was demonstrated that, unlike conventional alkaline electrolysis where KOH-based systems are generally more effective, urea-assisted systems exhibit superior performance in NaOH-based electrolytes, which provides more favorable kinetics for the electrocatalytic urea oxidation process. Furthermore, the accumulation of carbonate ions was shown to negatively affect UOR kinetics by increasing polarization resistance and partially blocking surface sites, highlighting the necessity of controlling electrolyte composition in practical systems. These findings open new opportunities for the rational design of efficient urea-assisted electrolyzers for green hydrogen generation.
An Efficient Synthetic Route to Substituted Xanthene Analogues
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Varenichenko, S. A.; Kovtun, A.V.; Farat, V. K.; Farat, O. K.
ENG: The reactions of N-[(9-chloro-1,2-dihydrocyclopenta[b]chromen-3-yl)methylene]-Nmethylmethanaminium and N-[(11-chloro-7,8,9,10-tetrahydrocyclohepta[b]chromen-6- yl)methylene]-N-methylmethanaminium perchlorates with (1- phenylethylidene)malononitrile were studied in boiling acetonitrile in the presence of piperidine. These reactions led to the formation of new organic dyes, [(2E)-1-phenyl-3- (9-piperidin-1-yl-1,2-dihydrocyclopenta[b]chromen-3-yl)prop-2-en-1- ylidene]malononitrile and [(2E)-1-phenyl-3-(11-piperidin-1-yl-7,8,9,10- tetrahydrocyclohepta[b]chromen-6-yl)prop-2-en-1-ylidene]malononitrile, obtained in high yields. The structures of the products were confirmed by 1H NMR spectroscopy, mass spectrometry, and elemental analysis. The observed spin-spin coupling constants indicated that the products adopted the E-configurations of the double bonds. The reaction mechanism was determined to proceed via a Knoevenagel condensation followed by nucleophilic substitution of chlorine with a piperidine fragment. Spectroscopic investigations of the dyes were performed in organic solvents, in particular acetonitrile and chloroform. For [(2E)-1-phenyl-3-(9-piperidin-1-yl-1,2-dihydrocyclopenta[b]chromen3-yl)prop-2-en-1-ylidene]malononitrile, the absorption maximum was ~605 nm, and the emission maximum was ~685 nm, with a quantum yield of 34.62% in acetonitrile and 16.84% in chloroform. In contrast, [(2E)-1-phenyl-3-(11-piperidin-1-yl-7,8,9,10- tetrahydrocyclohepta[b]chromen-6-yl)prop-2-en-1-ylidene]malononitrile exhibited an absorption maximum at 607 nm with negligible fluorescence. The synthesized dyes may be of interest to researchers in the field of dye chemistry and related areas.
Elastomeric Compositions With Rice Husk-Based Bio-Ingredients
(Ukrainian State University of Science and Technologies, 2026) Sokolova, Lina О.; Ovcharov, Valery І.; Hrydnieva, Тatyana V.; Тertishniy, O.A.; Тyshchenko, V.O.
ENG: Іn the context of the global growth of green chemistry and the circular economy, the use of crushed rice husk (CRH) as a bio-ingredient in elastomeric compositions offers an environmentally sustainable alternative. It has been found that modification of the husk with surfactants, in particular the cationic quaternary ammonium salt (QAS-4) synthesized from sugar-industry biowaste, significantly improves the interaction between the husk and the rubber matrix, increases the degree of crosslinking, and enhances the physical and mechanical properties of the rubbers, such as tear and heat resistance. Experimental results showed that compositions with CRH modified with QAS-4 demonstrate advantages in processability, including preservation of the rubber compound’s plasticity and acceleration of sulfur vulcanization, as well as improved performance characteristics of industrial rubbers compared with traditional fillers. The use of CRH, especially in a modified form, is a promising direction for creating environmentally friendly and costeffective elastomeric compositions.
Electrochemical Corrosion Properties and Protective Performance of Coatings Electrodeposited from Deep Eutectic Solvent-Based Electrolytes: A Review
(Materials, 2025) Protsenko, Vyacheslav S.
ENG: The application of deep eutectic solvents (DESs) as an innovative class of environmentally friendly liquid media represents a significant advancement in materials science, especially for the development and enhancement of structural materials. Among the promising applications, DESs are particularly attractive for the electrodeposition of corrosion-resistant coatings. It is established that corrosion-resistant and protective coatings, including those based on metals, alloys, and composite materials, can be synthesized using both traditional aqueous electrolytes and non-aqueous systems, such as organic solvents and ionic liquids. The integration of DESs in electroplating introduces a unique capacity for precise control over microstructure, chemical composition, and morphology, thereby improving the electrochemical corrosion resistance and protective performance of coatings. This review focuses on the electrodeposition of corrosion-resistant and protective coatings from DES-based electrolytes, emphasizing their environmental, technological, and economic benefits relative to traditional aqueous and organic solvent systems. Detailed descriptions are provided for the electrodeposition processes of coatings based on zinc, nickel, and chromium from DES-based baths. The corrosion–electrochemical behavior and protective characteristics of the resulting coatings are thoroughly analyzed, highlighting the potential and future directions for developing anti-corrosion and protective coatings using DES-assisted electroplating techniques.
Electrochemical Discharge of Nickel With Low Internal Stresses
(Oles Honchar Dnipro National University, Dnipro, 2025) Sknar, Yuri; Sknar, Irina V.; Butyrina, Tetiana E.
ENG: The work is devoted to the current topic of electrochemical separation of nickel with low voltages from sulfate electrolytes of electroextraction. Scrap processing of strategic nickel-containing superalloys with electroextraction of nickel is an urgent task today. Electrochemically deposited nickel is characterized by high internal tensile stresses, which leads to its delamination from the cathode surface. To reduce the internal stresses of nickel deposits obtained in such systems, it is proposed to use sulfur-containing organic compounds of sodium allylsulfonate, sodium orthoarylsulfonate, and sodium propynylsulfonate. It was established that allylsulfonate and orthoarylsulfonate practically do not affect the kinetics of nickel release. Propynyl sulfonate with a concentration of more than 5 mmol/l significantly inhibits the process of electrodeposition of nickel, which is related to the adsorption capacity of this compound with the triple bond present in the molecule. It is shown that due to the presence of a sulfo group in the composition of the molecules, the used organic additives contribute to the reduction of the internal stresses of nickel deposits. It was established that allyl sulfonate and orthoaryl sulfonate are the most promising reagents that contribute to reducing the internal stresses of electrodeposited nickel. Lowstress nickel deposits can be obtained in the range of current densities from 2 to 7 A/dm2 at a concentration of these additives from 15 to 30 mmol/l.
Electrodeposition of Ni-Based Composite Coatings Containing Cerium Compounds From a Deep Eutectic Solvent and their Electrocatalytic Performance
(Oles Honchar Dnipro National University, Dnipro, 2025) Protsenko, Vyacheslav S.; Shaiderov, Denys A.; Sukhatskyi, Oleksandr D.; Korniy, Sergiy A.
ENG: This work examines the electrodeposition of Ni-based composite coatings containing cerium compounds from a eutectic mixture of choline chloride and urea (reline), a typical deep eutectic solvent. The data reveal that depending on the concentrations of NiCl26H2O and CeCl37H2O dissolved in reline, coatings containing up to 49 wt.% cerium, present as embedded CeO2, can be formed within an electrochemically deposited nanocrystalline nickel matrix. Variation of the Ni(II) and Ce(III) salt concentrations strongly influences the resulting surface morphology. Reaction schemes for the formation of these composite coatings are proposed, and cyclic voltammetry with successive scan cycles was used to identify the potential windows in which the relevant electrochemical reactions occur in reline-based solutions. The deposited coatings were tested as electrocatalysts for water electrolysis in 1 M NaOH. Special attention was paid to the electrocatalytic activity of the Ni-based composite coatings toward the anodic oxidation of urea, a potential alternative to the oxygen evolution reaction in green hydrogen production. Incorporation of CeO2 into the nickel matrix led to a pronounced enhancement of electrocatalytic activity for hydrogen evolution, oxygen evolution and urea oxidation in alkaline aqueous solution. The proposed composite coatings may find application as multifunctional catalysts for green hydrogen generation. Moreover, adjusting the Ni(II) and Ce(III) concentrations in the deep eutectic solvent-based plating bath enables flexible and controlled tuning of the electrocatalytic behavior of deposited coatings.
Electrosynthesis of Ni-Fe Films With Enhanced Electrocatalytic Activity for Hydrogen Evolution From Alkaline Electrolyte
(Oles Honchar Dnipro National University, Dnipro, 2025) Sukhii, Mykhailo K.; Sknar, Iryna V.; Butyrina, Tetyana E.; Sknar, Yuri E.; Nefedov, Volodymyr G.; Polishchuk, Yuliya V.
ENG: The work is devoted to the topical issue of creating electrocatalysts for hydrogen evolution from alkaline electrolyte. The rapid development of hydrogen energy using the electrolytic method of hydrogen requires the use of cheap, resource-intensive and highly catalytic cathode materials. The most variable and flexible in control is the electrochemical method of synthesizing electrocatalysts of this type. A very promising material for cathodic hydrogen release is the Ni-Fe alloy. The limiting factor for its use is the high internal stresses that arise during its electrosynthesis. To reduce the internal stresses of Ni-Fe electrocatalyst films, sulfur-containing modifiers sodium allyl sulfonate and sodium saccharinate were used in this work, which were introduced into the methanesulfonate electrolyte of electrodeposition. It was established that increasing the concentration of sodium allyl sulfonate from 30 to 100 mmol/l leads to a decrease in internal stresses from 300 MPa to 100 MPa. The use of sodium saccharinate in a concentration of 0.5 mmol/l to 6 mmol/l contributes to a decrease in internal stresses from 300 MPa to 0 MPa. This effect of modifiers on internal stresses is associated with a change in the alloy structure due to the incorporation of sulfur and hydrocarbon residues of modifiers. It was found that the Ni-Fe alloy obtained in the presence of allyl sulfonate demonstrates high electroactivity, approaching the electroactivity of platinum. This effect is explained by an increase in defects in the crystal lattice and the presence of nickel and iron sulfide particles in the structure of the cathode material. It is recommended to carry out the electrosynthesis of Ni-Fe, as electrocatalysts for hydrogen evolution, from a methanesulfonate electrolyte containing 80–100 mmol/l of sodium allyl sulfonate in the range of current densities from 3 to 7 A/dm2.
The English Language Idioms Functioning in the Mass-Media Discource
(Bulletin of Science and Education, 2025) Kovalenko, Inna М.; Mykhailova, Alla S.; Oleshkevich, Іrina P.
ENG: The article deals with the contemporary media discourse, idioms that are widely used to create memorable and expressive images and associations. The relevance of the study of idioms in modern English-language media discourse lies in the fact that idioms are an integral part of language and culture, reflecting the peculiarities of thinking and perception of the world by people of different cultures and nationalities. Different types of idioms present in advertising and media space (newspapers, magazines) were considered, such as phrasal verbs, comparisons, metaphors, allegories, idiomatic expressions, and others. Each type of idiom has its characteristics and is used depending on the goals of the advertising campaign. Examples of idiom usage in advertisements from various industries such as the automotive industry, food industry, tourism, and others were considered. In each example, idioms were used to create an emotional appeal, establish empathy with the audience, and strengthen memorability.For idiom usage in advertising to be effective, it is necessary to consider the context, audience, goals, and features of the product or service. Advertising campaigns that use idioms can be successful and effective if they are correctly applied and align with the campaign's objectives. Idioms allow for the creation of unforgettable and emotionally appealing advertising, which can be used in various industries and on different platforms, including television, radio, print, and online advertising. Thus, the use of idioms in modern English-language media discourse is an effective tool for establishing an emotional connection with the audience and conveying key messages. However, for a successful advertising campaign, it is important to consider the cultural and social characteristics of the target audience and choose idioms that align with the audience's values and perceptions. Further research in this field may lead to the creation of new methods for using idioms in advertising and improving the effectiveness of advertising campaigns.
Features of Elastomeric Compositions in the Presence of Regenerated Sunflower Oil Production Waste as Filler
(Oles Honchar Dnipro National University, Dnipro, 2015) Sokolova, Lina O.; Ovcharov, Valery I.; Toropin, Mykola V.; Burmistrov, Kostiantyn S.; Tyshchenko, Valeria O.
ENG: The paper investigates the peculiarities of the properties of elastomeric compositions based on butadiene-α-methylstyrene rubber of the Buna KER 1723 brand in the presence of regenerated sunflower oil production waste in comparison with the equal weight content (20.0 phr) of known mineral fillers. It has been shown that the hydrophobized products under study significantly affect the processibility of rubber compounds, the course of sulfur vulcanization at different temperatures, the level of rheokinetic characteristics, and the density of cross-links of elastomeric compositions. It has been established, that in terms of the rubber reinforcement factor, the spent adsorbent with 37 wt.% of the organic component (diatomite P), regenerated by two-stage washing with dichloroethane and petroleum ether, is superior to a product with 57 wt. % organic component (diatomite D), as well as chalk, but inferior to kaolin. Diatomite P can be recommended for use in industrial rubber formulations.
Gold Nanoparticles Stabilized With Aminopolycarboxylic Acids
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Тrunova, O. K.; Berezhnytska, O. S.; Rohovtsov, O. O.; Berzenina, Oksana V.; Khrokalo, L. A.; Semenets, Yu.V.
ENG: This study presents the synthesis, morphological characterization, and preliminary antimicrobial evaluation of novel colloidal gold nanoparticle (AuNP) systems stabilized with aminopolycarboxylic acids: ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS). These complexing agents act not only as chelators but also as simultaneous reducing and stabilizing agents in the formation of AuNPs, offering a green and environmentally friendly approach to nanomaterial fabrication. The synthesis was carried out under mild aqueous conditions without external protective additives, enabling the production of stable colloidal systems with minimal side products. The resulting nanoparticles were characterized by UV-Vis spectroscopy, FTIR spectroscopy, and scanning electron microscopy (SEM). Characteristic surface plasmon resonance (SPR) bands were observed in the 530–550 nm range, with their intensity and spectral position sensitive to pH, ligand nature, and stabilization time. The most stable and monodisperse systems were obtained at pH≈9, with spherical nanoparticles ranging in size from 8 to 20 nm. Particular emphasis was placed on evaluating the biological activity of the synthesized dispersions. Antimicrobial screening was performed against Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial strains. The results demonstrated moderate to high bactericidal activity, especially in EDTA-stabilized samples, likely due to enhanced surface stabilization and potential ligand involvement in membrane interactions.
Granular Polymers With Immobilized N-Chlorosulfonamide Groups as Alternative Water Disinfectants
(Journal of Water and Health, 2025) Murashevych, Bohdan; Koshova, Iryna; Girenko, Dmytrо V.; Stepanskyi, Dmytro
ENG: In light of the deterioration of microbiological composition of natural and technical water, the development of new approaches to its disinfection is an important technological task. The use of chlorine-active compounds remains the most effective for this purpose, but traditional preparations such as sodium hypochlorite pose a number of environmental risks. This paper describes the processes of treating model microbiologically contaminated solutions with granular styrene-divinylbenzene polymers with immobilized N-chlorosulfonamide groups. In this case, chlorine is released from the polymer surface into the solution due to chlorination of the amine components of the microbial cell. The amount of chlorine released is proportional to the degree of microbial contamination. The main factors influencing the disinfection rate and the characteristics of the chlorine emission process are the intensity of stirring, the type and concentration of the microorganism, and the surface area of the polymer. The treatment is effective against individual Gram-positive and Gram-negative bacteria, including multiresistant ones, fungi, and multi-culture natural media. The use of this method for water disinfection potentially allows avoiding chlorine overdose, minimizing the formation of toxic chlorine-containing by-products, and ensuring long-term protection of water from recontamination during storage.
Green Approach to the Synthesis of Gold Nanoparticles With Antimicrobial Activity Using Plant Extracts Based on a Deep Eutectic Solvent
(Ukrainian State University of Science and Technologies, 2025) Skіba, Marharyta I.; Skyba, Y. M.; Kovalenko, Ihor L.; Gnatko, Olena M.; Radkevych, T. O.; Vorobyova, V. I.
ENG: Gold nanoparticles were synthesized by reducing hydrogen tetrachloroaurate(III) trihydrate (HAuCl4⋅3H2O) using plant waste (banana peel) extracts obtained using a deep eutectic solvent (DES) based on choline chloride. It was demonstrated that the plant waste (banana peel) extract obtained by DES allows the synthesis of spherical gold nanoparticles (Au NPs), characterized by a maximum plasmon resonance absorption peak at approximately λ=540–560 nm, with an average nanoparticle size range of 31–68 nm with a zeta potential value of –33 to –36 mV, depending on the initial concentration of the precursor stabilizer used in the synthesis process. Choline chloride-based DES was used as a new alternative to conventional solvents for ultrasonic extraction of active substances from plant waste, in particular banana peel. Low-temperature eutectic solvents based on choline chloride were compared with glycerol and lactic acid in a ratio of 1:3 and water 10–30%. It was found that choline chloride and glycerol in a ratio of 1:3 with a water content of 30% are highly effective for the extraction of flavonoid compounds from plant waste (banana peel). The influence of extraction parameters, namely sample-to-solvent ratio and extraction time, on the content of extracted flavonoids and antioxidant activity of the extract was studied using the methods of determining antioxidant activity by ferric ion reduction (FRAP) and the ABTS test (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). It was established that the extracted flavonoid content using DES is 222–521 mg/100 g. It was established that the sample-to-solvent ratio (1:45–1:80) and the extraction time of 10–30 min allow obtaining the antioxidant activity value of banana peel extracts, determined by the FRAP and ABTS methods: 20–60 mmol/l and 15–35 mmol/l. The gold nanoparticles obtained using DES extracts of banana peel showed higher antibacterial activity against E. coli compared to the DES extract of banana peel and non-sterilized gold nanoparticles
Influence of Cathode Material on the Electrochemical Synthesis of Sodium Hypochlorite in Coaxial Flow Cells
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Girenko, D.; Murashevych, В.; Demchenko, Р.; Velichenko, О.
ENG: The features of synthesis of sodium hypochlorite solutions in membraneless flow electrolyzers are mainly determined by the electrolyzer design, electrolysis parameters, and electrode material. In most models, titanium is traditionally used for the cathode, while other materials have not been sufficiently studied in this role. This article discusses alternative cathode materials, such as titanium Grade 2 pre-treated in different ways, various types of platinized titanium, palladium-plated titanium, and stainless steel. A comparative analysis of their effect on the efficiency of the electrolysis process and the quality of the resulting solutions is performed. It is shown that smooth titanium Grade 2 is the optimal cathode material for preparing low-concentration (up to 1500 mg/L) sodium hypochlorite solutions in many respects. An increase in the specific surface area of this material reduces the current efficiency of hypochlorite. However, when using titanium, the electrolysis process is the most energy-intensive. To reduce electricity consumption by 20–25%, it is advisable to use cathodes made of platinized titanium. Heat treatment of platinized titanium under air atmosphere additionally leads to an increase in the integral current efficiency of sodium hypochlorite from 65 to 70% and a slight increase in the energy efficiency of synthesis. The cathode material has practically no effect on the sodium chlorate impurity content, and all obtained solutions have sufficiently high purity for medical applications.
Influence of Solid-State Polycondensation Conditions on the Intrinsic Viscosity of Recycled Poly(Ethylene Terephthalatе)
(Ukrainian State University of Science and Technologies, 2026) Chervakov, Denys O.; Ved, Viktor V.; Fedan, V. V.; Sukhyy, Kostyantyn M.; Chervakov, Oleh V.
ENG: The study investigates the influence of solid-state polycondensation (SSP) conditions on the change in intrinsic viscosity (IV) of recycled poly(ethylene terephthalate) (PET) processed via a bottle-to-bottle technology. Experimental work was carried out within the temperature range of 110–1600C while varying the duration of SSP. It was found that during SSP at 110–1300C, the intrinsic viscosity of PET-BTB increased by 23–34%, whereas the melt flow index (MFI) decreased by up to 54%, indicating a nonlinear relationship between IV and MFI. A mathematical model was proposed to predict IV as a function of temperature, SSP duration, and MFI value. Validation of the model revealed a deviation not exceeding 6%, which confirms its high practical reliability. The proposed approach enables a reduction in the scope of experimental work required for optimizing SSP conditions of recycled PET and assessing its recyclability toward products with the desired level of physical and mechanical properties.
The Influence of Solid-State Polycondensation of Polyethylene Terephthalate on Its Rheological Properties
(Ukrainian State University of Chemical Technology, Dnipro, 2024) Chervakov, Denys O.; Ved, V. V.; Fedan, V. V.; Sukhyy, Kostyantyn M.; Chervakov, Oleh V.
ENG: The influence of solid-state polycondensation conditions on the rheological properties of polyethylene terephthalate was determined. Mathematical models describing the dependence of the melt flow rate of both virgin and recycled polyethylene terephthalate on the time and temperature of the solid-state polycondensation process were developed. A correlation between the melt flow rate and the average molecular weight of polyethylene terephthalate was demonstrated. Experimental studies showed that conducting solid-state polycondensation of recycled polyethylene terephthalate at temperatures ranging from 130 оC to 160 оC for 3 hours produces polymeric materials with higher molecular weight and, consequently, improved performance properties.
Influence of Synthesis pH on Structural, Dielectric and Magnetic Properties of MnFe2O4
(Oles Honchar Dnipro National University, Dnipro, 2025) Frolova, Liliya A.; Saltykov, Dmytro Yu.; Holub, Iryna V.; Bila, Оlena V.
ENG: Dispersed manganese ferrite particles were obtained by a combined co-precipitation method at different pH of the initial solution (7–12). The structural, morphological, optical and magnetic properties of the synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, and vibrational magnetometry. The XRD results showed that MnFe2O4 has a cubic spinel crystal structure with an average crystallite size of 14–65 nm. The presence of additional phases is observed at low pH and pH greater than 12. Ferritization significantly depends on pH, which affects the phase composition of the products and the size of the crystallites. In addition, with an increase in pH from 7 to 12, the percentage of microstresses and the density of dislocations decreases. The obtained MnFe2O4 samples exhibit ferrimagnetic properties, the highest saturation magnetization value of 56.8 Emu/g is achieved at pH 10. In addition, the coercive force changes from 5 to 50 Oe with increasing pH due to the increase in crystallite size.
The Influence of the Degree of Moisture and Temperature of Starch Heat Treatment on the Viscosity of Paste Solutions
(Ukrainian State University of Science and Technologies, 2025) Nikolenko, Mykola V.; Sakhno, Yu.; Myrhorodska-Terentieva, V. D.; Myrhorodska, K. D.; Terentiev, Vyacheslav V.
ENG: The possibilities of heat treatment of starch have not yet been fully utilized. The fact is that thermal treatment of starches can produce not only «split» starches, but also «cross-linked» starches, in which polycarbohydrate molecules are additionally bound by ether bonds. The latter can be formed by condensation of polycarbohydrate hydroxyl groups during starch heating without the use of additional chemical reagents. It has been suggested that the content of hydrate water in dry starch is an important factor because it can correlate with the number of intermolecular essential links of polycarbohydrate chains. Therefore, the purpose of the research is to determine the dependence of the viscosity of the paste solutions on the degree of initial humidity and the temperature of the heat treatment of starch. Studies have shown that there is a linear correlation between the kinematic viscosity of starch solutions and the hydrated water content in starch. The dependence of the viscosity of native starch paste solutions on the heat treatment temperature has the form of a convex curve, whereas for vacuum starch this dependence has the form of a rapidly declining exponential curve. It has been shown for the first time that preliminary vacuum dehydration of starch allows for a significant reduction in the temperature and time of starch dextrinization. FTIR studies of dehydrated starch spectra show a decrease in the number of intermolecular hydrogen bonds, which may be the main reason for the acceleration of their thermal degradation compared to starches with a higher degree of moisture.
Influence of Various Factors on the Emission of Hypochlorous Acid from Sodium Hypochlorite Solutions Into the Air
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Murashevych, B.; Girenko, D.; Lebed, O.; Maslak, H.; Netronina, O.
ENG: Active chlorine compounds are powerful microbicidal agents traditionally used for surface disinfection. Following the COVID-19 pandemic, the potential use of these compounds for air treatment to mitigate the spread of infectious diseases has been actively studied. A promising approach involves developing disinfection systems capable of maintaining a sufficient concentration of the most effective gaseous antimicrobial component of active chlorine –hypochlorous acid (HOCl) – in indoor air. This study investigates the influence of various factors on the emission of HOCl into the air during its bubbling through sodium hypochlorite (NaOCl) solutions. A colorimetric method for determining the total chlorine content in the air has been refined. The effects of key parameters of NaOCl working solutions on the HOCl concentration in the air have been examined. It has been demonstrated that, at a constant pH of the working solution, the total chlorine content in the air is strictly proportional to the HOCl concentration in the solution, which, in turn, can be determined using established molar distribution diagrams of active chlorine species. When electrochemically generated NaOCl working solutions (containing approximately 1100 mg/L of active chlorine) are used without additional composition adjustments, the HOCl concentration in the air can be maintained within the range of 6.0–11.6 mg/m3 . The findings of this study can be applied in the development of fumigation-based air disinfection systems and in the assessment of air contamination risks associated with chlorine-containing compounds.
An Integral Metric for Evaluating Electrocatalytic Activity
(Chemija, 2025) Protsenko, Vyacheslav S.; Makhota, Dmytro O.
ENG: This study introduces an integral metric of electrocatalytic activity, which is based on the comparison of the area under the polarisation curve in current density vs overpotential coordinates over a specific chosen overpotential range. This metric is applied to evaluate and compare several electrocatalysts, allowing for a more comprehensive understanding of electrocatalytic performance. Unlike traditional metrics, which characterise electrocatalyst behaviour under specific conditions (e.g. a particular overpotential or current density), the proposed integral metric provides a broader evaluation over a wide operational range. This approach is particularly useful for electrocatalysts with different Tafel slopes and polarisation characteristics. The metric is shown to be invariant to the shape of the polarisation curve and can be applied even when the exact form of the analytical dependence is unknown. The application of this metric holds promise for both fundamental studies in electrocatalysis and for practical applications in selecting the most efficient electrocatalysts for various technological processes.
Interaction of Labile N-Alkoxy-N-Chloro-N’-Arylureas and N-Acetoxy-Nalkoxyureas With Trimethyl Phosphite
(Oles Honchar Dnipro National University, Dnipro, 2025) Shtamburg, Vasiliy G.; Klots, Evgeniy A.; Anishchenko, Andrey A.; Shtamburg, Victor V.; Shishkina, Svitlana V.; Mazepa, Alexander V.; Kravchenko, Svetlana V.
ENG: The freshly synthesized N-alkoxy-N-chloro-N’-4-bromophenylureas undergo reaction with trimethyl phosphite in diethyl ether at room temperature yielding respectively dimethyl N-alkoxy-N-(N’-4- bromophenylcarbamoyl)phosphoroamidates with high yields. The unstable N-alkoxy-N-chloro-N’-phenylureas, freshly synthesized at -30°C, interact with trimethyl phosphite in diethyl ether at this low temperature to produce previously unknown dimethyl N-alkoxy-N-(N’-phenylcarbamoyl)phosphoroamidates. This reaction is the first example of the nucleofilic substitution at the nitrogen atom for unstable N-alkoxy-N-chloro-N’-phenylureas. Careful conditions selection and precise control made it possible to pevent premature destruction of the starting N-alkoxyN-chloro-N’-4-bromophenylureas and N-alkoxy-N-chloro-N’-phenylureas. In contrast, N-acetoxy-N-alkoxyureas do not react with trimethyl phosphite under the same conditions. The structures of the resulting dimethyl N-alkoxy-N- (N’-4-bromophenylcarbamoyl)phosphoroamidates and dimethyl N-alkoxy-N-(N’- phenylcarbamoyl)phosphoroamidates were confirmed by ¹H, ³¹P, and ¹³C NMR spectroscopy, as well as mass spectrometry. A comparative analysis of ¹H, ³¹P and ¹³C NMR spectra of these dimethyl N-alkoxy-N-(N’- arylcarbamoyl)phosphoroamidates with those of dialkyl N-alkoxy-N-(N’-4- nitrophenylcarbamoyl)phosphoroamidates revealed numerous shared features and general structural characteristics of N-alkoxy-N-(N’-arylcarbamoyl)phosphoroamidates
Interaction of N-Alkoxy-N-Chloro-N’-Arylureas With Trialkyl Phosphites AS a Route to Dialkyl N-Alkoxy-N-(N’’- Arylcarbamoyl) Phosphoramidates. Synthesis
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Shtamburg, Vasiliy G.; Klots, Evgeniy A.; Anishchenko, Andrey A.; Shishkina, Svitlana V.; Mazepa, Alexander V.; Kravchenko S. V.
ENG: This article is dedicated to the study of the interaction of some kinds of N-alkoxy-Nchloroureas, such as N-alkoxy-N-chloro-N’-(4-nitrophenyl)ureas, N-ethoxy-N-chloroN’-(2-nitrophenyl)urea, N-methoxy-N-chloro-N’-(4-chlorophenyl)urea, and N-alkoxyN-chloro-N’-alkylureas, with trialkyl phosphites. The stable N-alkoxy-N-chloro-N’-(4- nitrophenyl)ureas interact with trialkyl phosphites in diethyl ether at room temperature with preferential formation of dialkyl N-alkoxy-N-(N’-4- nitrophenylcarbamoyl)phosphoramidates. N-Ethoxy-N-chloro-N’-(2-nitrophenyl)urea reacts with trimethyl phosphite in diethyl ether at room temperature giving dimethyl Nethoxy-N-(N’-2-nitrophenylcarbamoyl)phosphoramidate. The interaction of unstable Nmethoxy-N-chloro-N’-(4-chlorophenyl)urea with trialkyl phosphites in diethyl ether gives dialkyl N-methoxy-N-(N’-4-chlorophenylcarbamoyl)phosphoramidates with good yields. N-Alkoxy-N-chloro-N’-alkylureas react with trimethyl phosphite under the same conditions with selective formation of dimethyl N-alkoxy-N-(N’-alkylcarbamoyl)phosphoramidates with excellent yields. In all these cases, the nucleophilic substitution at the nitrogen atom is accompanied by a further Michaelis-Arbuzov rearrangement. The original method of creating molecules containing a P–N bond is proposed. The structures of dialkyl Nalkoxy-N-(N’-arylcarbamoyl)phosphoramidates and dimethyl N-alkoxy-N-(N’- alkylcarbamoyl)phosphoramidates have been confirmed by 1H, 31P, and 13C NMR spectroscopy, and mass spectrometry. The synthesized dialkyl N-alkoxy-N-(N’- arylcarbamoyl)phosphoramidates and dimethyl N-alkoxy-N-(N’- arylcarbamoyl)phosphoramidates simultaneously possess structural features of both phosphoramidates and ureas, and may be regarded as potential biologically active substances.
Investigation of Structural, Magnetic, Optical, and Photocatalytic Properties of Fe/CoFe2O4 Composite
(MDPI AG, Basel, Switzerland, 2025) Frolova, Liliya A.; Protsenko, Vyacheslav S.; Butyrina, Tetiana E.
ENG: A Fe/CoFe2O4 nanocomposite was synthesized in one step by a hydrothermal method by processing the created iron and cobalt hydroxocomplexes. For precise characterization of the structure and morphology, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy (UV-vis-DRS) were used. It was found that the obtained samples have a pronounced spinel crystalline structure, with the presence of metallic iron. The crystal size was determined by various methods and was 93–104 nm. The saturation magnetization, determined from the hysteresis loop, was 189.24 Emu/g, and the force coefficient was 602 Oe. UV-vis-DRS studies showed a band gap of 2.1 eV. The photocatalytic degradation of ibuprofen, streptocide, furacilin, methylene blue, and tetracycline was investigated under the influence of UV radiation in the presence of a photocatalyst. It was confirmed that the rate of degradation of pollutants obeys pseudo-first-order kinetics. Analysis of the constant rate of reactions showed that in order of decreasing stability, pharmaceutical drugs can be dissolved as follows: ibuprofen → streptocide → furatsilin → methylene blue → tetracycline. It was found that the ratio of photocatalyst and hydrogen peroxide concentrations is important for the destruction of more stable pollutants. The effect of hydrogen peroxide and catalyst concentrations is extremely strong. For unstable compounds, the most influential factor is the duration of treatment.