The article analyzes the advantages of using glass-ceramic materials for immobilizing low- and medium-level radioactive waste, which have high operational characteristics, availability of raw materials, and environmental friendliness of the technology. Requirements for the properties of solid matrices and the characteristics of glassy-ceramic materials compositions for immobilizing radioactive waste were determined. A composition of glass-ceramic material based on the SiO2–Al2O3–B2O3–CaO–P2O5–TiO2–ZrO2–CeO2–ZnO–BaO–MoO2 system in the region of hydroxyapatite crystallization has been developed. It has been established that the mechanism of phase formation in glass consists of the formation of a dissipative crystalline structure of glass-ceramic materials during low-temperature heat treatment. The composition of the material was modified by introducing cesium and strontium salts, and the efficiency of their incorporation into the glassy-ceramic materials structure under thermal treatment was determined. Simulation experiments were carried out to study the retention of these elements in the material structure. The developed high-strength glass-ceramic material is characterized by a fine-dispersed structure and a hydroxyapatite content of 50 vol.%. This material can retain approximately 80-95% of cesium and strontium elements in its structure, which determines the prospects for using the proposed material as a solid matrix for immobilizing radioactive waste.
The development of new functional composites for directed transport and controlled release of bioactive compounds (BACs) is one of the priority tasks of modern surface chemistry and pharmaceutical technology. The work analyzes hybrid organic/inorganic systems based on poly(2-hydroxyethyl methacrylate) (PHEMA) filled with nanosilica as stimulus-sensitive matrices for biomedical applications. It was established that the kinetics of BACs release from these composites is determined by a combination of their composition and structural parameters. The regulation of the desorption process of components is achieved by creating additional cross-links in the polymer matrix, introducing nanosilica as a filler and using water as a pore former. At the same time, the efficiency of BACs retention by the matrix and the rate of their diffusion significantly depend on the physicochemical parameters of the environment, in particular on the pH value, which is a key factor in modulating interactions in areas with different intensities of the inflammatory process. The presented analytical study summarizes the mechanisms of interaction of BACs with composites based on PHEMA and nanosilica. The limits of dominance of various types of influences, including electrostatic attraction, steric hindrance and the formation of hydrogen bonds during the binding and desorption of BACs, were determined. A comprehensive understanding of these fundamental processes allows us to transform approaches to creating innovative systems with controlled release of BACs in accordance with modern requirements of the pharmaceutical industry.
This study presents a comprehensive investigation of the mechanosynthesis of molybdenum disilicide (MoSi2) nanopowder and its subsequent application in the fabrication of ceramic heating elements for stacks of solid oxide fuel cells (SOFCs). SOFCs are a promising technology for stationary energy generation due to their high efficiency in converting chemical energy into electricity (up to 65%) and heat (up to 30%), fuel flexibility (hydrogen, hydrocarbons, CO, etc.), and absence of platinum-group catalysts. MoSi2 was selected as a material for heating elements due to its high electrical and thermal conductivity, exceptional thermal stability, resistance to oxidation, and ability to withstand high operating temperatures, making it suitable for rapid and uniform heating in SOFC stacks. The influence of the powder-to-ball mass ratio (1:10 and 1:20) and milling parameters on the mechanosynthesis process was systematically studied. It was found that higher energy input significantly accelerates the formation of the MoSi2 phase, reducing the reaction time by approximately 1.5 times. X-ray diffraction analysis confirmed the formation of the MoSi2 phase with minor residual molybdenum, while silicon was found to be X-ray amorphous, indicating its high reactivity and structural disorder after mechanical activation. Energy transfer during milling and particle size distribution were analyzed to optimize synthesis parameters, ensuring uniform nanopowder morphology suitable for further processing. The synthesized nanopowder was used to prepare ceramic pastes for 3D printing via the robocasting method. The rheological properties of the pastes were optimized to allow stable extrusion and high-resolution printing of complex geometries. Key printing parameters, including extrusion rate, nozzle diameter, and printing speed, were adjusted to minimize defects and ensure the structural integrity of printed elements. After thermal treatment and sintering, the printed heating elements exhibited rapid and uniform temperature rise, demonstrating their suitability for integration into SOFC stacks and other high-temperature energy-generating systems.This work provides a detailed methodology for combining mechanosynthesis and additive manufacturing to produce high-performance ceramic components. The results contribute to the development of energy-efficient and reliable heating elements for advanced SOFCs and demonstrate the potential of MoSi2-based materials in high-temperature energy applications. Furthermore, the findings offer insights into controlling phase composition, particle morphology, and process parameters, which are critical for the scalable production of functional nanostructured ceramics.
Quercetin (3,3′,4′,5,7-pentahydroxyflavone) is a flavonoid well known for its redox activity, which type (antioxidant or prooxidant) strongly depends on its concentration, pH, and the redox properties of the surrounding biological environment. At alkaline pH (pH > 8), quercetin undergoes autoxidation to semiquinone and quinone species, accompanied by reactive oxygen species (ROS) generation, thus exhibiting pronounced prooxidant behavior. However, the application of quercetin in ROS-mediated anticancer therapy is limited by the slightly acidic extracellular pH of tumor tissues (~6.5–6.9), under which its autoxidation is inefficient. In this study, we demonstrate a significant enhancement of quercetin oxidation in the presence of CeO2-x and GdYVO4:Eu3+ nanoparticles under near-physiological pH conditions (6.7–7.8). Kinetic analysis shows that the experimental data for CeO2-x nanoparticles can be well described by the Michaelis–Menten model. In contrast, this model does not adequately describe the behavior of GdYVO4:Eu3+ nanoparticles. The higher activity of CeO2-x nanoparticles surpassing sufficiently the activity of GdYVO4:Eu3+ ones, can be attributed to the more favorable redox potential of the Ce3+/Ce4+ couple compared to the V4+/V5+ couple.
The in-plane conductivity of pure and aluminum-doped YBa2Cu3O7−δ single crystals was studied before and after long-term exposure in an air atmosphere. It was shown that prolonged exposure leads to an increase in the number of effective scattering centers for normal carriers. Aluminum doping partially slows down the degradation of conductive properties during the aging of experimental samples. The excess conductivity of the studied samples shows an exponential temperature dependence in a wide temperature range, and near Tc it is satisfactorily described by the Aslamazov–Larkin theoretical model. At the same time, long-term exposure significantly broadens the temperature range of the pseudogap state and substantially narrows the temperature interval of the linear dependence ρab(T). To investigate the peculiarities of the “tweed” structures, the fractal analysis method based on the box fractal dimension estimation was performed.
