Himičeskaâ fizika

The present scientific article encompasses an analysis of the physicochemical and optical characteristics, as well as adhesion properties of two luminescent materials based on yttrium aluminum garnet, doped with cerium. The aim of the study was to determine the potential usage of these luminescent materials in laser lighting devices. To achieve this, the luminescence spectrum and color diagrams were analyzed when the luminescent materials were subjected to laser radiation with various power and current values. The results revealed that both examined luminescent materials possess high luminous efficiency when current is applied. However, after six months of operation, the luminescent systems exhibited differences in their adhesion properties. Additionally, the study produced a block diagram of a device designed to analyze the physicochemical parameters of laser luminescent systems under the influence of laser radiation with λ = 405–450 nm. With the aid of this device, data on the characteristics of the luminescent materials under different current values were obtained, providing a more precise control over their degradation processes. The investigation demonstrated that both examined luminescent materials can be utilized in laser lighting devices, but one of the luminescent material samples proved to be a more stable and durable material due to its better adhesion with the substrate. The proposed results can be beneficial in the development of new laser lighting tools.

The kinetics was studied and the constants of the main stages of hydrogen separation and incorporation into steel in a solution of phosphoric acid containing a mixture of 1,2,4 triazole derivative IFKhAN-92 and KNCS were determined. The addition of IFKhAN-92 + KNCS mixture inhibits the reaction of cathodic reduction of hydrogen and its penetration into steel in H₃PO₄ solution. The inhibitory effect of this mixture is due to a decrease in the ratio of the hydrogen concentration in the metal phase to the degree of hydrogen filling of the surface. The decrease in the hydrogen concentration in the metal volume by the IFKhAN-92 + KNCS mixture determines the preservation of the plastic properties of steel during corrosion in H₃PO₄ solutions. The high efficiency of the IFKhAN-92 + KNCS composition, as inhibitors of cathodic reduction of hydrogen and its absorption, is the result of chemisorption of the organic component of the mixture on the surface of steel and the formation of a polymolecular protective layer.

The ignition of tableted samples (ρ = 1 g/cm³) of microparticles (d ≤ 63 microns) of anthracite by laser pulses (532 nm, 10 ns, (0.15–0.5) 10⁹ W/cm²) was studied. When the critical energy density H_cr⁽¹⁾ ≈ 0.15 J/cm² is exceeded, an optical breakdown of the sample surface occurs during the laser pulse and the formation of a plasma flare with a lifetime of ≥ 5 microseconds. The amplitude of the plasma glow, depending on the energy density of the laser pulses, is described in the framework of the optical breakdown model. The presence of the following atoms and molecules in plasma was identified by the luminescence spectra: C, C+, Ca+, Fe+, Fe, CN, C2, CO. At a density of H > H_cr⁽²⁾, in anthracite samples, as in hard coals, thermochemical reactions are initiated in the volume of microparticles, the release and ignition of volatile substances and №n-volatile residue in a submillisecond time interval.

The classical Heisenberg spin chain with competing exchange interactions of ferro-(F) and antiferromagnetic (AF) types has been considered. This model describes qualitatively properties of the edge-sharing cuprates. The model id characterized by the frustration parameter which is a ratio of the AF- and F-interactions. The ground state of the model is either ferromagnetic or singlet with helical spin correlations in dependence of the frustration parameter. The main attention is given to the study of excited states in the helical phase. These states are domain walls separating the regions with opposite chiralities. It is shown that these excitations are gapped and their energy scales the temperature region in which the phase transition from the helical to the ferromagnetic phase takes place. The calculated energies of domain-walls excitations are used for the determination of the Lifshitz boundary on the phase diagram.

The kinetic patterns of the reaction of phosphoenolpyruvic acid (PEP) with the NO donor – nitrosyl iron complex with penicillamine ligands (PEN) were studied using mass spectrometric analysis. It has been established that the PEP molecule in an aqueous solution interacts with PEN. The kinetic curves demonstrate the complex multi-stage nature of the reaction. A kinetic model of the process is proposed that quantitatively describes the experimental data.

The features of the influence of divalent cadmium and manganese ions on the ability of lecithin to form aggregates in water medium, its ζ-potential, and the state of the lipid peroxidation processes have been studied. The methods used were TLC, dynamic light scattering, and processing of UV spectra using the Gauss method. It was revealed that cadmium ions accelerate the processes of lipid oxidation in liposomes, and manganese ions inhibit them. At the same time, cadmium ions, as opposed to manganese ions, require more period to interact with the membrane structure of liposomes. The data obtained and the analysis of the literature allow us to conclude that the cadmium and manganese ions present in the solution influence the spontaneous aggregation of lecithin and participate at different stages of the oxidation process in accordance with their biological activity when entering the body.

Hybrid nanosystems based on magnetic iron oxide nanoparticles (IONPs) and human serum albumin (HSA), containing methylene blue (MB) as a model photosensitizer, have been synthesized. The resulting HSA@IONP nanosystems were characterized for size and composition using UV/visible spectrophotometry (particularly, using the Bradford method), dynamic light scattering, and electron magnetic resonance. A study of the dark and photoinduced cytotoxicity of MB, IONP, HSA@IONP, MB–IONP, MB–(HSA@IONP) on of human colon adenocarcinoma HCT116 cells was carried out. Under the experimental conditions, the difference between the dark and light-induced cytotoxicity of nanosystems on cells was significantly enhanced when the photosensitizer was immobilized on the surface of the carrier particles compared to free photosensitizer in equivalent concentrations.