Water and soil resources are one of the most important natural resources of a country, from which all the food needs of humans and animals are provided, but unfortunately, they are constantly exposed to encroachment and changes by human and non-human factors. Biochar is one of the solutions recently considered in international scientific forums for soil and water protection. In this study, carbon adsorbents' performance has been investigated to remove heavy metal pollutants. Carbon adsorbents, unlike resins that only deal with ion exchange, work in different environments, including in the presence of carboxyl, imidazole, sulfhydryl, amine, sulfate, phosphate, thioether, phenol, carbonyl, amide, and hydroxyl bases. In this study, the absorption rate of heavy trace elements with carbon adsorption and their efficiency has been investigated, and the results of pH and optimal concentration for carbon adsorption have been presented. A study has been done on the carbon absorbents used to separate heavy metals. Bio-carbon adsorbents are a cheaper and more effective alternative to separate metals and metal elements, especially in the separation of heavy metals in soil treatment. In this study, the amount of absorption in bio-absorbents, according to the cell structure and their types, has been investigated. The results show that the subsequent adsorption of bio-carbon adsorbent can be a suitable method for purifying soil from heavy metal ions.

Single-phase ground faults (SPGFs) in isolated neutral medium-voltage networks are difficult to detect, especially under high transient resistance. This paper proposes a centralized ground fault protection unit (CGFPU) that combines zero-sequence current (ZSC) magnitude and phase-angle analysis to enhance selectivity. Simulation results show that as transient resistance increases from 1 Ohm to 10 kOhm, fault currents decrease significantly, yet the CGFPU reliably identifies the faulty feeder by exploiting the characteristic 180° phase shift of ZSC phasors. The method remains selective with angular deviations up to ±20° and distinguishes between feeder and busbar faults. Compared with conventional amplitude- or model-based techniques, the proposed approach achieves faster detection, lower computational complexity, and robustness against unbalanced and charging currents. Furthermore, the CGFPU operates adaptively in alarm or trip mode depending on fault severity, thus preserving continuity for high-resistance faults and ensuring rapid isolation of bolted faults. These contributions establish a practical, scalable, and future-ready solution for SPGF protection in medium-voltage isolated neutral networks. © 2025 by the authors.

The current study provides a new leaching method for extracting valuable metals, such as uranium, vanadium, molybdenum, and rare earth metals (REMs), from black shale ores. Initial characterization indicated that these metals are encapsulated in hard “carbon-silica shells,” presenting severe extraction challenges. A novel low-temperature sintering process is considered in this work with ammonium hydrosulfate at 350 °C for 60 minutes, much lower than the conventional process of over 800 °C. The devised treatment effectively ruptures the protective shell, converting metal constituents into soluble forms. Subsequent leaching yielded good recovery rates: uranium (93.3%), vanadium (81.7%), molybdenum (82.2%), and REMs (78.3%). Thermogravimetric analysis revealed the stepwise decomposition mechanism and emission profiles upon sintering. The leaching parameters (solid-liquid ratio, temperature, time, and solution concentration) were optimized for maximum metal recovery, along with selective sorption conditions (pH, redox potential, and duration) and desorption variables. Additionally, the cost-effective production routes for vanadium concentrate were specified as ammonium metavanadate, molybdenum concentrate as calcium molybdate and REM concentrate as carbonates, instead of depending on high-pressure or high-temperature processes. Solid residue carbon flotation enrichment was accompanied by a recovery yield of 89.0% by weight of carbon, enabling enhanced utilization of the entire resource. Altogether, the adopted approaches offer a closed-loop, energy-saving pathway to the efficient recovery of the rare and essential metals from the black shale ore

A new iodine–dextrin–lithium complex (IDLC) was synthesized and structurally characterized as a hybrid supramolecular system combining antiseptic, stabilizing, and biocompatible components. The compound integrates iodine as the primary antimicrobial agent, lithium as a coordination and stabilization element, and dextrin as a biodegradable polysaccharide matrix enabling sustained release. Physicochemical analyses confirmed the formation of a uniform, thermally stable complex. Biological evaluation revealed strong bactericidal activity, with minimum bactericidal concentrations (MBCs) ranging from 1.95 to 15.63 µg mL−1 against both Gram-positive and Gram-negative pathogens, including multidrug-resistant Staphylococcus aureus and Acinetobacter baumannii. Cytotoxicity studies revealed moderate, concentration-dependent effects on human peripheral blood mononuclear cells (CC50 = 0.23–0.48 mg/mL; 11.7–24.4 μg I/mL) and low toxicity toward MDCK cells (CC50 = 10–20 mg/mL; 507–1014 μg I/mL), confirming a favorable safety profile. IDLC exhibited cytotoxic effects on tumor cell lines (HepG2, HeLa, AGS, K562, and H9) as well as on the normal MeT-5A cell line; however, the CC50 values are similar, and selectivity indices are close to 1, indicating no selective cytotoxicity toward tumor cells. Thus, IDLC demonstrates non-specific cytotoxicity at high concentrations, consistent with its iodine content. The research confirms that iodine can be effectively stabilized within a dextrin-lithium framework to yield a biologically active, thermally resistant complex, suitable for pharmaceutical use.

This paper addresses the problem of synthesizing four-link initial kinematic chains with rotational pairs for designing flat lever mechanisms with specified motion laws of the input and output links. The proposed method formulates the synthesis problem as an optimization process involving three moving planes Q, Q1 and Q2. Each plane performs distinct motions: Q is fixed, Q1 rotates around a point A, and Q2 undergoes plane-parallel motion. The goal is to determine the optimal position of point A ∈Q, B ∈Q1 and C ∈Q2 such that the distance between points B and C remains nearly constant across multiple configurations. The synthesis problem is reduced to a sequence of linear systems of equations corresponding to three iterative minimization stages: Determining the fixed-point A and the radius R for given points B and C; Determining the point B and radius R for a given point C; Determining the point C and radius R for a given point B. The algorithm uses a hierarchical optimization process to iteratively refine the positions of A, B, and C until convergence is achieved. The convergence criteria are defined by the small changes in the positions of these points and the radius R between iterations. The proposed method avoids solving a highly nonlinear system directly by decomposing the problem into simpler linear systems, ensuring computational efficiency and robustness. The solution provides the desired positions of the points, forming an open kinematic chain ABCD with three degrees of freedom. The approach is applicable to the synthesis of complex planar mechanisms with unrestricted parameters, making it a valuable tool for mechanism design. © The Author(s) 2026. This article is licensed under a Creative Commons Attribution NonCommercial-NoDerivatives 4.0 International, which permits the use, sharing, adaptation, distribution and reproduction in any medium or format, as long as appropriate credit to the original author(s) and the source is given by providing a link to the Creative Commons license. https://creativecommons.org/licenses/by-nc-nd/4.0/.

The sustainable operation of hydroponic systems depends on maintaining the chemical stability of circulating nutrient solutions and preventing the accumulation of toxic compounds. The accumulation of phytotoxic ammonium, heavy metals, and organic metabolites in recirculating nutrient solutions remains one of the key challenges limiting the efficiency, sustainability, and scalability of hydroponic cultivation. This review provides a comprehensive comparative analysis of zeolites, activated carbons (ACs), and their functionalized and composite forms as key sorbents for nutrient management, contaminant removal, and environmental safety in hydroponic cultivation. Natural zeolites, with their well-defined crystalline structure and high ion-exchange selectivity toward ammonium and heavy metal cations, enable effective NH4+/K+ balance regulation and phytotoxicity mitigation. ACs, characterized by high specific surface area and tunable surface chemistry, complement zeolites by offering extensive adsorption capacity for organic compounds, root exudates, and pesticide residues, thereby extending the operational lifespan of nutrient solutions and improving overall system performance. Further advancements include the integration of zeolites and ACs with two-dimensional (graphene, g-C3N4) and three-dimensional (MOF, COF) frameworks, yielding multifunctional materials that combine adsorption, ion exchange, photocatalysis, and nutrient regulation. Transition-metal modification, particularly with Fe, Mn, Cu, Ni, and Co, introduces redox-active centers that enhance sorption, catalysis, and phosphate stabilization. The comparative synthesis reveals that the combined application of zeolite- and carbon-based composites offers a synergistic strategy for developing adaptive and low-waste hydroponic systems. From a techno-economic and environmental standpoint, the judicious application of these materials paves the way for more resilient, efficient, and circular hydroponic systems, reducing fertilizer and water consumption, lowering contaminant discharge, and enhancing food security. This systematic review was conducted according to the PRISMA 2020 guidelines. Relevant studies were identified through Scopus, Web of Science, and Google Scholar databases using specific inclusion and exclusion criteria.

Presented universal recommendations for the reduction of crud formation, reviewing various aspects affecting the loss of diluent and extractant due to the formation of a third phase (crud), encountered in many hydrometallurgical plants using copper solvent extraction. In this paper introduce the reasons of the crud formation, description of the stable emulsions containing solid particles and choice of technological scheme. An analysis of operations to be considered in the operation of copper solvent extraction plants is presented, due to the deterioration of copper grade below 0.5% in ore and the increase in aluminum content up to 20–25%. Results of use of extraction properties of modified extractants of ACCORGA series and unmodified extractant Lix984N on pregnant leached solution of the most important deposits (Almaly and Aktogay) are given. It is established that for solutions of Almaly deposit, ACCORGA5640 and unmodified Lix984 extractants have high selectivity to copper. Distribution of iron, silica, and copper ions during extraction was studied, and it was found that high selectivity to copper/iron and copper/silica is possessed by extractant Lix 984N, ACCORGA5640. It was found that for solutions of the Aktogay deposit, the ratio of interphase suspension in both extractants is the same, and phase separation in experiments with the use of extractant Lix 984N was 10 s shorter with the use of extractant ACCORGA5640. It was found that the addition of ACCORGACR60 reagent in the amount of 5-10 ppm also leads to a decrease in the volume of crud by 13%, for a stronger suppression of crud.

This paper investigates the interaction between rolling stock and railway track during the emergency braking of a passenger train. A detailed simulation model of a train consisting of a locomotive and twenty passenger cars was developed in the Universal Mechanism software environment. The model accounts for longitudinal, lateral, and vertical vibrations, as well as nonlinear elastic couplings and random track irregularities. Simulation results show that the estimated braking distance is 583 m, which complies with current regulatory standards. The analysis of coupler forces revealed that braking is generally shockless due to buffer devices, except at the locomotive-first car connection. Derailment is possible only under severe track irregularity conditions, while displacement of the rail-sleeper lattice caused by increased transverse forces does not result in derailment. The findings contribute to improving railway safety assessment and support the development of intelligent monitoring and warning systems for modern "smart train" applications. © The Author(s) 2026. This article is licensed under a Creative Commons Attribution NonCommercial-NoDerivatives 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/.

The asbestos wastes were exploited for extraction of magnesium by agitation leaching process in atmospheric conditions, using hydrochloric acid as the leaching agent. The study was focused on investigating the kinetics of magnesium leaching. The effects of some variables, including stirring speed (150−300 r/min), leaching temperature (25−90 °C), leaching duration (10–60 min), the concentration of hydrochloric acid (150–300 g/L) and the solid - liquid ratio (1:2–1:5), on the leaching rate were carefully evaluated. It was found that increasing the stirring speed, leaching temperature, and concentration of hydrochloric acid can significantly increase the rate at which magnesium is leached. A comprehensive kinetic scrutinization was performed by fitting the experimental data with exponential kinetic equation, Yander diffusion equation, Drozdov-Rotinyan equation, and Prout-Tompkins equation. Amongst all these tested kinetic equations, the diffusion-controlled process showed a higher goodness-of-fit with experimental data. Thermodynamic aspects were also appraised carefully. The apparent activation energy for the process was calculated to be 19.8 kJ/mol, indicating a relatively low-level energy needed to initiate the process efficiently. Overall, the current study provided insight into how changing certain parameters can affect the overall performance when attempting to extract magnesium from the asbestos wastes by leaching process.

This review presents a modern comprehensive analysis of the physicochemical characteristics of carbon materials for the sorption of gases. The main classes of carbon sorbents are considered as follows: nanotubes, activated carbon, graphene, fullerene, composite materials, and organic vapors. Modern methods of modification of carbon materials are systematized. Particular attention is paid to the effect of particle size, morphology, and porous structure on the kinetics and equilibrium characteristics of adsorption. The results of experimental and theoretical studies of the adsorption of the gases (CO2, SO2, NOx, H2S, NH3, and CO) are analyzed. A comparative economic analysis of carbon materials is carried out, taking into account the cost of production and estimated costs of modification. Modern areas of application of carbon sorbents are analyzed as follows: industrial gas purification, automotive filters, air conditioning systems, personal protective equipment, and gas sensors. Particular attention is paid to the study of the prospects and future of materials. Prospective development directions are considered, including the creation of hierarchically porous structures, the development of self-healing materials, and integration with artificial intelligence to optimize adsorption processes. The cost of graphene and nanotube production is predicted to decrease by 50–70% by 2030, which will lead to an expansion of their commercial application.