Himičeskaâ fizika

Fluorescent photoswitchable systems (FPSS) are organic molecular and organic-inorganic hybrid nanoscale systems that combine the properties of photochromes and fluorophores, i.e. the ability to change their fluorescent properties, intensity and/or emission spectrum under the action of light. The structure and mechanisms of action of FPSS of different types are considered, examples of application of FPSS in super-resolution microscopy, for visualisation of biological and inorganic nano-objects, recording of optical information, for anti-counterfeiting, as photonic molecular logic gates are given.

The effect of bilirubin on the spectral fluorescence properties of the cationic thiacarbocyanine dye Cyan 2 in the presence of DNA was studied. The Cyan 2 dye forms a non-covalent complex with DNA, which leads to an increase in the fluorescence of the dye. Interaction with bilirubin leads to effective quenching of dye fluorescence in complex with DNA (static mechanism), which can be used to construct a spectral-fluorescent sensor for bilirubin. The results of in vitro experiments are illustrated by in silico molecular docking experiments. The effect of Cu²⁺ ion additives can further enhance the quenching of dye fluorescence by bilirubin. Effective quenching constants and detection limits of bilirubin using the Cyan 2–DNA system (LOD and LOQ) are determined.

A kinetic model of hemolysis of erythrocyte suspension under the action of the azo generator of peroxide radicals AAPH has been developed. The model is based on the assumption of cell hemolysis as a macroscopic consequence of the process of lipid peroxidation developing in the lipid region of the membrane, that lead to the accumulation of a certain molecular product, the critical concentration of which causes hemolysis. The kinetic component of the model is implemented as a solution to the direct problem of chemical kinetics with an obtainment of kinetic curves of formation of the supposed hemolysis factors. Due to the heterogeneity of the erythrocyte population, their morphological and other characteristics, including the response to the effect of the hemolytic factor, are statistically distributed. In this regard, the Gaussian normal distribution function was used as a mathematical basis for an accurate solution to the problem of the relationship between the degree of hemolysis and the concentration of the acting factor. This made it possible to describe the results of the hemolytic experiment with a good approximation.

The results of the microstructure development study of ferritic/martensitic steel of the 12Cr type are presented. The steel samples were irradiated at 350 °С by 300 keV ⁸⁴Kr¹⁵⁺ ions up to a fluence of 1 ∙10²¹ m^-2 in a vacuum of about 7 ⋅ 10^-4 Pa. The experiment was carried out in relation to the storage of spent nuclear fuel for conditions of gaseous fission products introduction into the fuel cladding. It has been established that krypton implantation develops approximately the same microstructure regardless of the initial state of the sample (conventional heat treatment, namely – normalization followed by high tempering, or annealing at 350 °C for 70 h). Gas porosity is formed in the steel, the features of its development are studied by the depth of the path of the introduced ions using cutting out of TEM objects perpendicular to the irradiated surface. The steel surface is strongly oxidized during irradiation, apparently due to the ballistic effect (“driving” of oxygen atoms into the sample by bombarded ions due to insufficiently vacuum in the target area), since the non-irradiated side of the sample did not oxidize when held for 70 h at 350 °С during irradiation of first side. Based on the experimental results obtained, it was concluded that during storage of spent nuclear fuel under standard conditions stresses should not arise in the cladding of spent fuel rods due to gas swelling.

The distribution of electron density along the radius of nanoparticles in one- and two-component semiconductor systems at different temperatures and radii of nanoparticles has been obtained taking into account physicochemical processes on their surface. The influence of surface modification of In₂O₃ nanoparticles by CeO₂ nanoclusters in changing the distribution of conduction electrons and the magnitude of the electrostatic field in the nanoparticle volume is demonstrated. The role of these distributions in various physical and chemical phenomena involving semiconductor nanoparticles is discussed.

The equations of multimoment hydrodynamics are used to interpret flows behind the sphere that do not have axial symmetry. The equations of multimoment hydrodynamics follow from the equations for pair distribution functions. The derivation of the equations is free from approximations similar to the Boltzmann hypothesis. In accordance with the general approach, the pair function is represented as an infinite series of products of trajectory invariants with unknown coefficients. A finite number of terms are preserved in this series, which make it possible to construct asymmetric distributions of hydrodynamic values. Analytical expressions for the principal hydrodynamic values are presented. Solutions of nonlinear differential equations for unknown coefficients will make it possible to trace the evolution of the observed asymmetric flows, culminating in pronounced turbulence.

Numerical data are presented on the chain length of the so-called zero oxygen cycle, i.e. such a cycle in which ozone destruction does not occur as in purely catalytic cycles. The data correspond to the conditions of June 2000 at latitude 50 N in the altitude range of 15–55 km. Calculations were performed using the interactive two-dimensional SOCRATES model. Forecasts of atmospheric greenhouse gas content of the Intergovernmental Panel on Climate Change RCP 4.5 for the year 2000 were used as initial data for calculations. Calculations of the chain length of zero cycles were carried out using the algorithm proposed earlier by the author for determining the speed of the limiting stage of the catalytic cycle.