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Comparison of the effectiveness of rice husk ash for solid phase synthesis of wollastonite and diopside

https://doi.org/10.58224/2619-0575-2026-9-1-1
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Abstract
Objectives: This study aims to evaluate the prospects of using rice husk ash for the production of calcium-magnesium silicates and to identify differences in the solid-phase synthesis processes of wollastonite and diopside based on rice husk ash.
Methods. X-ray quantitative phase analysis was used to analyse the obtained samples of synthetic wollastonite and diopside. The porosity of calcium-magnesium silicates was evaluated by a static volumetric method using low-temperature nitrogen adsorption. The elemental composition of the samples was determined using an Oxford INCA X-max 80 energy dispersive detector, and electron microscopic analysis was performed using a Jeol JSM7001F scanning microscope.
Results. Experimental data comparing the properties of synthesized diopside and wollastonite showed that wollastonite is characterized by high porosity and average particle size compared to diopside due to the lower temperature of solid-phase synthesis. The structure of synthetic wollastonite is distinguished by the presence of large irregularly shaped inclusions with a small amount of needle-like particles, while synthesized diopside does not contain needle-like particles, and the inclusions are characterized by smaller size and uniform distribution throughout the volume.
Conclusions. When obtaining calcium-magnesium silicates by solid-phase synthesis based on rice husk ash, the yield of the final product synthetic diopside is significantly higher than that of synthetic wollastonite. The process of synthesizing diopside is less labor-intensive and time-consuming, but more energy-intensive due to the higher synthesis temperature of diopside.
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Influence of technological parameters of potassium chloride production on corrosion-abrasive wear of double-layer steel 1.4462

https://doi.org/10.58224/2619-0575-2026-9-1-2
Abstract
The paper presents the results of laboratory studies of corrosion-abrasive wear of a screw dissolver made of duplex steel 1.4462 in an environment simulating potassium chloride production conditions (4RU of JSC "Belaruskali"). The influence of mechanical impurities (abrasive), temperature (105 °C), pH (4-8), artificial air supply, and incomplete immersion mode was experimentally studied. It has been established that the presence of abrasive increases the mass loss rate by 10 times (up to 0,015 g/day) compared to purely chemical corrosion [2]. The most intense pitting damage is observed in areas with oxygen access. An alkaline environment (pH= 8) promotes the formation of protective deposits, while an acidic one (pH= 4–7) intensifies corrosion [7]. Equipment operation with incomplete immersion of the agitator increases the corrosion rate by 40 % [2, 9]. Duplex steel 1.4462 shows high resistance to chemical corrosion, but its service life is sharply reduced under the combined influence of abrasive and non-standard operating conditions [2, 20]. Practical recommendations for extending equipment service life are given.
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Mathematical modeling of a solid oxide fuel cell

https://doi.org/10.58224/2619-0575-2026-9-1-3
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Abstract
Objectives: development of a mathematical model to describe the phenomena occurring in a medium-temperature solid oxide fuel cell. Solving the model equations requires finding a number of kinetic parameters, including the rate constants of electrochemical reactions.
Methods. To determine the viscosity of polymer solutions, their molecular weight and to study the adsorption of k-carrageenan on CX, the method of capillary viscometry was used. The assessment of the stability of the zones over time was carried out photometrically.
Results. The mathematical model is based on a system of partial differential equations and includes material and heat balance equations, as well as charge balance relationships. An algorithm for numerically solving the mathematical model equations and a corresponding software module for calculating the equations implemented in the Python programming language have been developed.
Conclusions. The developed mathematical model adequately describes the processes occurring at the electrodes of a medium-temperature fuel cell. The optimal fuel-to-oxidizer ratio was determined to be 1:10.
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Phase formation in triple salt systems Rb2MoO4–AMoO4–R(MoO4)2 (A = Mg, Ca, Mn, Co, Ni, Zn, Sr, Cd, Ba, Pb; R = Zr, Hf) and some properties of triple molybdates Rb5A0.5R1.5(MoO4)6

https://doi.org/10.58224/2619-0575-2026-9-1-4
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Abstract
As a result of studying the possibility of phase formation in triple salt systems Rb2MoO4–AMoO4–R(MoO4)2 (A – divalent elements; R = Zr, Hf) phases of the composition Rb5A0.5R1.5(MoO4)6, were obtained, which are assigned to a large family of ternary molybdates with the general formula M5A0.5R1.5(MoO4)6 (M – single valent element, A – divalent element, R = Zr, Hf) and represent a series of isostructural substances crystallizing in trigonal syngony (sp.gr. R3c или R3) [1, 2]. Crystallographic and thermal characteristics of the synthesized compounds were determined.
Methods. The subsolidus structure of the ternary salt systems Rb2MoО4–АMoO4–R(MoO4)2 was established using the “intersecting cuts” method. polycrystalline samples The powder samples compounds Rb5А0.5R1.5(MoO4)6 (A = Mg, Ca, Mn, Co, Ni, Zn, Sr, Cd, Ba, Pb; R = Zr, Hf) were obtained by solid-phase synthesis at 500–530°C.
Results. The subsolidus structure of the ternary salt systems Rb2MoO4–AMoO4–Zr(MoO4)2 (A = Mn, Pb,), Rb2MoO4–AMoO4–R(MoO4)2 (A = Zn, Cd, R = Zr, Hf) was established. The Rb5A0.5R1.5(MoO4)6 (А = Mg, Ca, Mn, Co, Ni, Zn, Sr, Cd, Ba, Pb; R = Zr, Hf) were obtained in powder form, their crystallographic and thermal characteristics were determined. IR and Raman spectra were recorded and analyzed for the compounds Rb5A0.5Zr1.5(MoO4)6 (A = Ni, Со, Mg, Zn), Rb5Ba0.5Zr1.5(MoO4)6.
Conclusions. Phase formation in ternary salt systems Rb2MoO4–AMoO4–R(MoO4)2 (A = Mg, Mn, Zn, Ni, Co, Cd, Ca, Pb, Sr, Ba; R = Zr, Hf) was studied and a subsolidus structure was established for six of them. Compounds Rb5A0.5R1.5(MoO4)6 were obtained by solid-phase synthesis at 500–530°C and belong to a large family of ternary molybdates with the general formula M5A0.5R1.5(MoO4)6 (M – single valent element, A – divalent element, R = Zr, Hf) and crystallize in two structural types: molybdates with large divalent metals (A = Ca, Sr, Ba, Pb) – in the structural type Tl5Pb0.5Hf1.5(MoO4)6 (пр.гр. R3, [2]), molybdates with divalent metals whose radius is less than 1Ǻ (A = Mg, Mn, Zn, Ni, Co, Cd) – in the structural type K5Mg0.5Zr1.5(MoO4)6 (пр.гр. R3c, [1]).
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Development and research of formulations for the production of functional ceramic materials

https://doi.org/10.58224/2619-0575-2025-8-4-1
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Abstract
The authors investigated a mixture for producing Ceram Bond ceramic adhesive (Bredent, Germany). The microstructure of the initial powder and the resulting coating after sintering at 980°C were analyzed. The resulting compositions are easily manipulated under industrial conditions and possess optimal processing properties.
Objectives: Research and development of new, effective functional ceramic coating compositions for dental prosthetics that meet high quality and durability requirements.
Methods. Analytical and experimental chemistry methods were used, as well as modern instruments and equipment. The chemical and phase composition was studied using an X-ray fluorescence spectrometer. The elemental composition of the experimental samples was determined using an energy dispersive attachment to a scanning electron microscope. The granulometric composition of the masses was determined using laser diffractometry. The microstructure of the powder and ceramic adhesive was examined using a scanning electron microscope. The structure of the coatings was recorded using an optical microscope. The preparation of the ceramic adhesive was carried out by wet grinding. The determination of water absorption, open porosity and apparent density was carried out using a vacuum chamber connected to a vacuum pump. The calculation of these parameters was carried out according to classical formulas.
Results. The analysis of the main physico-mechanical characteristics of a sample of a mixture in a paste-like state of the Ceram Bond brand, the Bredent trademark (Germany) is carried out. The compositions of experimental samples have been developed, their physico-mechanical properties have been determined, and the advantages and disadvantages of introducing flat glass and fused quartz into the combat have been identified. It has been established that coatings based on Ceram Bond adhesive are characterized by the presence of a large number of microcracks, and experimental formulations differ in a small number or completely absence of microcracks, which indicates its higher quality.
Conclusions. As a result of the work carried out, a mixture for the production of ceramic adhesive of the Ceram Bond brand of the Bredent trademark (Germany) was investigated. Experimental formulations have been developed for the production of ceramic adhesives based on fused quartz and tempered flat glass. The microstructure of the initial powder and the coating based on it after sintering at a temperature of 980℃ has been studied. It has been established that coatings based on Ceram Bond adhesive are characterized by the presence of a large number of microcracks, and the developed formulations differ in a small number or complete absence of microcracks, which indicates their higher quality.
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Comparison of modifying effect of wollastonite in polyvinylchloride and epoxy composite materials

https://doi.org/10.58224/2619-0575-2025-8-4-2
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Abstract
To investigate the grain-size and phase compositions and properties of natural and synthetic wollastonite fillers and to establish the nature of their modifying effect in polymer composite materials using the example of polyvinyl chloride thermoplastic and epoxy resin thermoset.
Methods. X-ray quantitative phase analysis was used to study the filler samples, and porosity was determined using mercury porosimetry and gas absorption. The particle size of wollastonite was determined by laser diffraction. The thermal stability of the filled composites was evaluated on a derivative thermogravimetric analyser, and the thermal stability of polyvinyl chloride materials was evaluated using the Congo red method. Dynamic mechanical analysis was performed on a DMA 242 Netzsch device.
Results. The particle size distribution and phase composition of natural and synthetic calcium silicate samples, their porosity and pH of aqueous extract were studied. The influence of wollastonite properties on the viscosity of the obtained polymer-filler mixtures, the thermal stability and wear resistance of the filled composites, as well as on the tensile strength and relative elongation of polyvinyl chloride compositions was established.
Conclusions. Studied calcium silicates have proven effective for both epoxy and polyvinyl chloride materials. Despite the similarity in phase composition and acid-base characteristics of the surface, natural and synthetic wollastonite differ in particle size distribution and porosity. Natural filler is more promising for creating heat-resistant polyvinyl chloride compositions and wear-resistant epoxy compositions, while synthetic wollastonite based on rice husks provides an increase in the dynamic modulus and glass transition temperature of both types of polymers. Studies have shown that the modifying effect of the studied fillers is more prominent in epoxy polymers due to their influence on the formation of the polymer matrix cross-linked structure.
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Study of the cerebroprotective effect of a new derivative of hydroxybenzoic acid – the dikali salt N–(3-hydroxybenzoyl)taurine in various disorders of cerebral circulation

https://doi.org/10.58224/2619-0575-2025-8-4-3
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Abstract
The 21st century is not only a time of progress in innovative technologies and artificial intelligence, but also a time of global downgrade and early development of serious health disorders, especially oncological and cardiovascular diseases. Currently, various cerebrovascular disorders have become widespread, which are the main limitation factors in rational therapy. This is due to the complications of primary diagnosis of the disease and its confirmation, as well as the problems in the application of early neuroprotection and rehabilitation. The aim of the study. The research of new compound’s neuroprotective properties: the dipotassium salt of N-(3-hydroxybenzoyl)taurine, which is a derivate of hydroxybenzoic acid, by the different types of vascular (blood circulation) disorders in the brain. Materials and methods. The examination of the dipotassium salt of N-(3-hydroxybenzoyl)taurine, as a derivate of hydroxybenzoic acid. Establishing the neurological status using the Combs & D`Alecy scale and the Gracia scale. Results. The research results let to suggest the cerebroprotective properties of a new hydroxybenzoic acid derivate, which demonstrates potential comparable to Citicoline, Nicergoline, and Acetylsalicylic acid in decrease the damage of the neuropsychiatric consequences of ischemic injury. The examine compound, like these other drugs, exhibits properties aimed at stabilizing cerebral circulation and reducing the manifestations of endothelial dysfunction. Conclusions. According to study findings the dipotassium salt of N-(3-hydroxybenzoyl)taurine exhibits cerebroprotective effects in various cerebrovascular disorders.
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Quantum chemical modeling оf aqueous mustard gas solutions

https://doi.org/10.58224/2619-0575-2025-8-4-4
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Abstract
Objective: to conduct quantum chemical modeling of a sulfur mustard molecule in an aqueous medium in the built–in parameter mode and in the mode of added molecules. After optimization by thermodynamic parameters, to study possible molecular and structural changes of mustard gas in the composition of the medium.
Methods. The Gaussian software package with the GaussView visualizer was used to construct and visualize the structure of the sulfur mustard molecule and its interaction with the aquatic environment. To carry out the calculation (calculation tipe FREQ), the standard Gaussian ab initio – Hartley-Fock (RHF) and post-Hartley-Fock (MP2) methods were chosen, which alternated with calculations based on the theory of the density function (DFT): B3LYP and B3LYP-FC. The semiempirical RPM6 method is used as a boundary factor.
Results. It is shown that only a comprehensive analysis of the state of the molecule makes it possible to identify the specific contribution of each type of interaction to the structure and properties of the molecule. In an aqueous environment, the mustard gas molecule has a high stability potential, but exposure to a real molecular environment leads to a change in polarizability, atomic charge, and dipole moment vector, and in the excited state of the molecule, one of the C1-Cl1 bonds is maximally activated, practically doubling its length.
Conclusions. Despite the very poor solubility of mustard gas in water, its intermolecular interaction with the medium leads to a redistribution of energy characteristics and the formation of a nonequilibrium polarizable state of the mustard molecule in the structure of the aquacomplex, possible further destruction with the formation of toxic products, including onium cations. Further development of the obtained results will make it possible to justify the choice of conditions for targeted activation of the mustard gas molecule for detoxification in aqueous media and body fluids.
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Effect of amphiphilic polymers on the photodynamic activity of methylene blue and rose bengal in vitro experiments

https://doi.org/10.58224/2619-0575-2025-8-4-5
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Abstract
Objectives: To study the effect of amphiphilic polymers on the dark and photoinduced toxicity of dyes with photosensitizing properties – methylene blue (MB) and rose bengal (RB) – in in vitro experiments.
Methods. In vitro experiments were carried out on human lung carcinoma A549 cells and on cultures of gram-negative (Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus) bacterial cells using a phototherapeutic LED with a wavelength of λ = 530 nm (for the RB) or λ = 660 nm (for the MB).
Results. Amphiphilic polymers (Pluronic F-108 and poly-N-vinylpyrrolidone) were shown to enhance the dark and photoinduced toxicity of dyes. MB was also shown to exhibit greater activity (compared to RB) in photodynamic inactivation of Gram-negative bacteria, while RB (compared to MB) was shown to exhibit greater activity in the inactivation of Gram-positive bacteria.
Conclusions. MB in combination with amphiphilic polymers is a potential drug of choice for both photodynamic therapy (PDT) of cancer and antibacterial PDT of Gram-negative bacteria. At the same time, RB-based systems hold promise for the development of antibacterial PDT of Gram-positive bacteria.
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Influence of the complex phytogenic additive “Resovet” on detoxification systems, antioxidant protection, productivity and intestinal microbiocenosis in broilers under mycotoxicosis conditions

https://doi.org/10.58224/2619-0575-2025-8-4-6
Abstract
Mycotoxin contamination of feed poses a serious threat to the poultry industry, causing significant economic losses. Traditional adsorbents are ineffective against a wide range of toxins and can reduce the nutritional value of feed. Therefore, developing strategies to activate the animal's endogenous detoxification systems is a pressing issue. This study examined the efficacy of the complex phytogenic supplement (CPS) "Rezovet," containing N-acetylcysteine (NAC), alkylresorcinols, and indole compounds, under experimental mycotoxicosis induced by zearalenone (ZEN) and ochratoxin A (OA). An in vitro experiment on the human hepatoma cell line HepG2 demonstrated that "Rezovet" and its components reliably activate nuclear factor 2 (NRF2), the main regulator of the antioxidant and detoxification response. NRF2 activation was accompanied by an increase in glutathione-S-transferase (GST) gene mRNA expression and its total activity. Furthermore, NAC and indole-3-propionic acid induced a cytoprotective autophagic response in ZEN-exposed cells. Inhibition of autophagy by chloroquine eliminated the protective effect. In an in vivo experiment on Cobb-500 broilers (n=120), the addition of Rezovet (0.5 kg/t feed) to a diet contaminated with ZEN (0.5 mg/kg) and OA (0.25 mg/kg) significantly (p<0.05) reduced liver damage and oxidative stress (a 35% decrease in malondialdehyde levels, a 50% increase in glutathione), while simultaneously increasing GST activity by 40%. Significant improvements in productivity were recorded: livestock survival increased by 4.2%, live weight at 28 days increased by 8.5%, and feed conversion improved by 5.7% compared to the group receiving mycotoxins alone. Metagenomic analysis revealed a 152% increase in the proportion of the commensal bacterium Akkermansia muciniphila in the caecal microbiome and a suppression of urease-producing bacteria (Proteus spp., Klebsiella spp.) in the litter. The synergistic mechanism of action of Rezovet, combining the activation of cellular defense systems and the modulation of microbial communities through mechanisms described in the theory of microbial autoregulation, is discussed. Rezovet is shown to be an effective non-adsorptive agent for the biological detoxification of mycotoxins and microbiome management.
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