Igor A. Lebedev

This study analyzes the influence of environmental parameters on the efficiency of photocatalytic processes for air purification. Modern photocatalytic air purification systems utilize light-activated semiconductor materials to generate reactive oxygen species capable of oxidizing pollutants to less toxic products. Experimental data indicate significant progress in the development of photocatalysts based on oxide and heterostructured materials. However, the high activity of photocatalytic materials demonstrated in laboratory conditions is not always reproducible under real-world environmental conditions. The study focused on the influence relative humidity, solar radiation intensity, ambient temperature, and mass transfer conditions on the kinetics of photocatalytic reactions and the availability of active surface sites. It was found that the effect of humidity is nonlinear and is determined by the balance between the formation of hydroxyl radicals and the competing adsorption of water molecules and target pollutants. The efficiency of photocatalytic processes under real-world conditions is determined not only by external environmental parameters but also by the structural design of the systems themselves. Integrated photocatalytic structures, such as fibrous membranes and composite materials, offer the most promise. These structures provide simultaneous filtration, adsorption, and catalytic oxidation of pollutants, as well as improved mass transfer to active sites. This architecture significantly improves the stability and reproducibility of photocatalytic activity under varying environmental conditions. A further evaluation of practical efficiency was conducted, taking into account the formation of reaction intermediates and their potential impact on human health. It was shown that the use of photocatalytic oxidation without preor concomitant filtration can lead to the formation of undesirable byproducts, whereas combined systems provide more thorough air purification and reduce the negative impact on cardiorespiratory parameters. Overall, the obtained results indicate the need to move from a material-based approach to a systems-based design of photocatalytic technologies, taking into account their real-world operating conditions.

A bstract: The BM@N experiment (Baryonic Matter at the Nuclotron) is the first fixed-target experiment at the JINR NICA accelerator complex. In this work, data on the interactions of a carbon-ion beam with kinetic energies of 4.0A GeV and 4.5A GeV with C, Al, Cu, and Pb targets are used to measure transverse momentum spectra and rapidity distributions of Λ hyperon yields. The results are compared with the predictions of DCM-SMM, UrQMD, and PHSD transport models and with the Λ yield measurements in other experiments at similar collision energies.

The recently proposed two-component Tsallis-Hagedorn Model with Transverse Flow (THMTF) function, which is the sum of thermodynamically consistent Tsallis function with embedded transverse flow and inverse power-law function (which is asymptotic of Hagedorn function at high p_T values), has described quite well simultaneously the experimental midrapidity p_T spectra of the charged pions and kaons, protons and antiprotons in the whole measured p_T range up to 20 GeV/c at all ten multiplicity classes in proton-proton collisions at sqrt(s)=7 and 13 TeV at the LHC. Dependencies of non-extensivity parameter, q, kinetic freeze-out temperature parameter, T₀, momentum scale parameter, P₀, and power-index n of the two-component THMTF function on <dN_ch/dη> in proton-proton collisions at sqrt(s)=7 and 13 TeV have been analyzed and interpreted. Analyzing <dN_ch/dη> dependencies of parameters T₀ and <β_T>, the border <dN_ch/dη> values of transition towards plateau region of kinetic freeze-out temperature (T₀) (and simultaneous emergence of transverse flow) and probable onset of deconfinement phase transition (towards QGP-like state) have been estimated to be <dN_ch/dη>≈ 7.6±0.9 and <dN_ch/dη>≈ 9.0±1.0 in proton-proton collisions at sqrt(s)= 7 and 13 TeV, respectively. These estimates made using THMTF function in present work have been above but close to the corresponding <dN_ch/dη> ≈6.1±0.3 and <dN_ch/dη> ≈7.1±0.2 estimates of possible onset of deconfinement phase transition in proton-proton collisions at sqrt(s)= 7 and 13 TeV, respectively, made in our earlier works using Hagedorn function with embedded transverse flow. Our estimates are consistent with and complement the corresponding early result ((dN_ch/dη) ≈ 6±1) of Campanini and Ferri for probable onset of deconfinement phase transition, obtained from analyses of the experimental <p_T> versus <dN_ch/dη> curves and extracted experimental EOSs, and squared speed of sound in proton-proton and proton-antiproton collisions in wide energy, sqrt(s)= 31-7000 GeV, interval. The mean number of partons participating in a scattering, n_α=5, has been estimated from extracted average value of power-index n in the analyzed proton-proton collisions. This suggests that g+q→meson+q and g+g→meson+g gluon fragmentation reactions are the main mechanisms for high p_T meson production in proton-proton collisions at the LHC. The obtained significant differences in <dN_ch/dη> dependencies of parameters q and n for pions and kaons, on the one hand, and for (anti)protons, on the other hand, can imply that pions and kaons demonstrate features of local thermalization in proton-proton collisions at the LHC with high enough multiplicity, whereas (anti)protons show significant deviations due to non-thermal production mechanisms. The Pearson coefficients of linear correlation have been calculated between various parameters of the two-component THMTF function in proton-proton collisions at sqrt(s)= 7 and 13 TeV and compared with those obtained recently in Xe+Xe and Pb+Pb collisions at the LHC.

We analyze the centrality (⟨N_part⟩) dependencies of midrapidity transverse momentum (p_T) spectra for identified light-flavor hadrons (charged pions and kaons, protons and antiprotons) in asymmetric p+Pb collisions at √s_nn = 5.02 TeV at the LHC. Using the new two-component Tsallis-Hagedorn Model with Transverse Flow (THMTF), we describe the ALICE experimental data up to p_T = 20 GeV/c across seven multiplicity classes. To reveal potential system-size dependencies, these results are systematically compared with symmetric Pb+Pb collisions at √s_nn = 2.76 and 5.02 TeV. It is estimated that collective radial flow emerges at ⟨N_part⟩ ≈ 4.0 ± 0.5 along with simultaneous transitioning of kinetic freeze-out temperature (T₀) to a nearly plateau region in p+Pb collisions. The kinetic freeze-out temperature (T₀) appears to demonstrate distinct centrality dependencies in small and large collision systems before reaching a stable plateau. In p+Pb collisions, T₀ initially rises up to its threshold value before stabilizing, suggesting that high energy densities in central p+Pb events might cause the compact system to decouple rapidly before undergoing significant expansion. Conversely, in Pb+Pb collisions, T₀ steadily decreases up to a larger threshold ⟨N_part⟩ value before reaching a plateau. This initial downward trend of T₀ in Pb+Pb collisions is consistent with the larger volume of heavy-ion fireballs, which may undergo more prolonged hydrodynamic expansion and extensive cooling before reaching the low-density decoupling limit. In both p+Pb and Pb+Pb collision environments, central collisions point toward enhanced thermalization, as deduced from decreasing-with-centrality trend of non-extensivity parameter q. Parameter q hierarchy (q (mesons) > q (baryons)) suggests that baryons may form predominantly in the highly thermalized core. In both p+Pb and Pb+Pb systems, the momentum scale parameter (P₀) rises steadily with centrality and correlates strongly positively with the average flow velocity (< β_T >), suggesting that larger pressure gradients may simultaneously drive collective flow and high-p_T particle production. However, at high p_T, the power-index n points to potentially different dynamics between the two systems. While large-scale Pb+Pb collisions exhibit spectral flattening likely related to strong hydrodynamic pressure, the p+Pb system shows a stable n for mesons (consistent with vacuum-like jet fragmentation), but a rising-with-centrality trend of n for protons and antiprotons. This rise of power-index n may indicate intermediate-p_T baryon enhancement via parton recombination/coalescence. These different physical trends are supported by Pearson correlation analyses of extracted model parameters in p+Pb and Pb+Pb collision systems. The results of present work establish critical benchmarks for theoretical models describing the transition from microscopic interactions to collective behavior in high-energy collisions.

In this work, we study the anisotropy of elemental groups of cosmic rays using data from the KASCADE experiment. The problems of determining primary energy and mass associated with fluctuations in the development of extensive air showers are discussed in detail. To address these issues, a method is used that suppresses the influence of these fluctuations on the estimation of primary energy and mass. The proposed approach is based on the use of lessening fluctuation curves, whose behavior is largely insensitive to shower-to-shower fluctuations during the development of extensive air showers. This allows, firstly, to significantly reduce errors in primary energy estimation and, secondly, to analyze individual showers. The approach also enables simultaneous analysis of showers arriving at substantially different zenith angles θ . To study cosmic-ray anisotropy, we analyzed right ascension versus declination distributions for five elemental groups (p, He, C, Si, and Fe). Analysis of experimental data from the KASCADE collaboration revealed significant differences in the distributions of these groups in equatorial coordinates, which may indicate a directed structure in cosmic-ray fluxes of different elemental composition. The observed features may point to the influence of nearby spiral arms and the Galactic magnetic field structure on the propagation of cosmic rays.

Results of the BM@N experiment at the Nuclotron/NICA complex on the production of protons, deuterons and tritons in interactions of an argon beam of 3.2 A GeV with fixed targets of C, Al, Cu, Sn and Pb are presented. Transverse mass spectra, rapidity distributions and multiplicities of protons, deuterons and tritons are measured. The results are treated within a coalescence approach and compared with predictions of theoretical models and with other measurements.

In this paper, we investigated fractal cluster structures of colloidal particles in tin dioxide films obtained from lyophilic film-forming systems SnCl₄/EtOH/NH₄OH with different pH levels. It was revealed that at the ratio Sn > Cl₂ > O₂, N₂ = 0, and pH = 1.42, the growth of cross-shaped and flower-shaped structures of various sizes from several μm to tens of μm is observed. At the ratio Cl₂ > Sn > O₂ > N₂ and pH = 1.44, triangular and hexagonal structures are observed, the sizes of which are on the order of several tens of micrometers. The growth of hexagonal structures is probably affected by the presence of nitrogen in the film, according to the elemental analysis data. At the ratio Sn > Cl₂ > O₂ > N₂ and solution pH of 1.49, the growth of hexagonal and cross-shaped structures is observed, whereas flower-shaped structures are not observed. Hierarchical flower-like and cross-shaped structures are fractal. The shape of microstructures is directly related to the shape of the elementary cells of SnO₂ and NH₄Cl. A direct dependence of the formation of hierarchical structures on the volume of ammonium hydroxide additive was found. This allows for controlling the shape and size of the synthesized structures when changing the ratio of the initial precursors and influencing the final physicochemical characteristics of the obtained samples.

In this paper, thin films based on tin dioxide containing hierarchical structures were synthesized. The process of “growing” these structures was carried out by introducing ammonium hydroxide into the composition of the initial film-forming solutions. The shape and volume of the hierarchical structures were regulated by the amount of introduced ammonium hydroxide. The optical properties of the obtained samples were also studied for further use as transparent conductive coatings. The films were applied using spray pyrolysis. During mapping, it was found that the greatest accumulation of tin was observed along the contour of the structures. Whereas oxygen and chlorine were distributed relatively uniformly over the surface of the samples. Elemental analysis of the samples showed that in all samples the ratio of elements was as follows: Sn>O2>Cl2. The highest tin content was in the sample synthesized from the initial solution containing 0.8 ml of ammonium hydroxide. To determine the effect of the content of hierarchical structures on the optical properties, transmission spectra of the synthesized samples were recorded. The analysis of the results showed that with an increase in the addition of ammonium hydroxide in the composition of the initial solution, the transmittance of the samples decreases, but not critically. They still remain optically transparent.

Among a large number of physical and chemical methods for obtaining materials with various functional characteristics, one of the very interesting and simple methods is sol-gel technology. Materials synthesized using sol-gel technology have high chemical homogeneity, which is definitely a big plus. And by changing the initial environmental conditions and solution parameters, it is possible to control the size and shape of the particles obtained, as well as the pore structure of the synthesized products. At present, much attention is paid to the study of hierarchical structures based on tin dioxide. Since they are distinguished by a large surface area, stable physicochemical properties, low cost of production, environmental friendliness of the method, as well as high surface permeability and low density. This article describes the results of the synthesis of hierarchical structures in thin films based on tin dioxide. The initial solution is a lyophilic film-forming system SnCl₄/EtOH/ NH₄OH. A direct dependence of the formation of hierarchical structures on the volume of ammonium hydroxide additive was found. This helps to control the shape and size of the synthesized structures when changing the ratio of the initial precursors. And as a consequence, it allows influencing the final physical and chemical characteristics of the obtained samples for their further use as transparent conductive coatings, sensors for various gases (including toxic ones), in solar panels, etc.