Recently, chaos theory and its applications have garnered the attention of many scholars. In this paper, a novel 4D dynamical system that can generate a four-wing hyperchaotic attractor and a double-wing chaotic attractor is presented. The dynamical behavior of this system is investigated using several numerical tools, including bifurcation diagrams, the spectrum of Lyapunov exponents, and phase plots. It is shown that the proposed system has multiple positive Lyapunov exponents for a wide range of parameters, which establishes its hyperchaotic behavior. Additionally, the multistability of this system is analyzed carefully through the coexistence of periodic, chaotic, and hyperchaotic attractors. The hyperchaotic patterns of this system render it suitable for encrypting multimedia data. An efficient, fast, and secure audio cryptographic algorithm is developed based on the hyperchaotic sequences generated from this system. Experimental tests are carried out to verify the performance and security of the proposed encryption method.

We have investigated the influence of finite number of particles used in molecular dynamics simulations on the fluctuations of thermodynamic properties. As a case study, the two-dimensional Lennard–Jones system was used. The 2D Lennard–Jones is an archetypal system and a subject of long debate about whether it has continuous (infinite-order) or discontinuous (the first-order) melting transition. We have found, that anomalies on the equation of state (the van-der-Waals or Myer–Wood loops), previously considered a hallmark of the first order phase transition, are at best at the level of noise, since their magnitude is the same as the amplitude of pressure fluctuations. So, they could be regarded as a statistically unsignificant effect. Also, we estimated inherent statistical noise present in computer simulations, and came to the conclusion, that it is larger than predicted by statistical physics, and the difference between them (called algorithmic fluctuations) may be due to the computer-related issues.

Tetracene nanocrystals prepared by the reprecipitation method are investigated using magnetophotoluminescence, steady-state optical absorption and emission spectroscopies. The steady-state absorption spectra indicate that the tetracene nanoparticles possess a crystalline structure. The magnetic field dependence of photoluminescence for tetracene nanoparticles has a range almost 40 times smaller than that for tetracene macrocrystals. This result is interpreted within the framework of a theoretical model based on the solution of the diffusion equation for a restricted spherical volume. The calculations show that this decrease in magnetic field dependences of photoluminescence can be sensitive to the size of tetracene crystals. According to the theoretical model, the triplet-triplet annihilation rate increases in nanostructured tetracene.

A model describing the graphitization of CVD diamond under the action of femtosecond laser radiation is proposed. The model combines thermal and kinetic aspects, taking into account the phase transition of diamond into graphite upon reaching critical conditions (temperature or charge carrier density). A mathematical model of the temperature field for a laser source is presented taking into account the dependencies for enthalpy and polarization. A mathematical model of the diamond-graphite phase transition under laser radiation is developed within the framework of the charge carrier density equation. The governing equations were presented in finite-difference form and discretized using a five-point stencil on a uniform grid. The finite-difference equations were solved using the explicit Euler scheme. Numerical simulation of diamond graphitization allowed us to estimate the key features of the initial stage of the process.

A multispectral single-pixel imaging system operating at three wavelengths – 800 nm, 1050 nm, and 1550 nm – was developed for the imaging of natural materials, such as nuts. Spectral multiplexing of structured illumination patterns was realized using optical elements, and radiation modulation was performed using a digital micromirror device. Data on the integral intensity of the radiation scattered from the object was collected using a collecting lens and one InGaAs photodetector. In accordance with the proposed scheme, images of 25 objects at wavelengths of 800 nm, 1050 nm and 1550 nm were reconstructed. The resolution of the obtained images was 64 by 64 pixels, the time of obtaining one image was about 40 seconds. Experimental results demonstrated the successful reconstruction of images of natural samples exhibiting distinct spectral features, confirming the potential of the system for material characterization and classification.

This work investigates ion transport in glass nanopipettes with tip diameters in the range of 80–100 nm, filled with phosphate-buffered saline. A combination of experimental measurements and theoretical modeling is employed. A coupled Poisson-Nernst-Planck-Navier-Stokes model is used to describe the ion transport, incorporating electroosmotic flow, electrophoresis and interionic effects. The theoretical results are in good agreement with experimental current to voltage characteristics. Comparison between modeled and measured data enables estimation of nanopipette geometry with good accuracy. The simulations also reveal characteristic spatial distributions of ionic flow in the aperture area of the nanopipette tip, governed by electroosmosis and the tip shape. These findings provide insights into nanoscale ion transport phenomena relevant for analytical and biological applications.

The half metallic transformation of MoSeS dichalcogenide structure upon doping with a transition metal is explored in this work. Additionally, the effect of doping on its adsorption capacity for CO, CO2, NO, and NO2, H2, H2O, H2S, and NH3 gases is investigated. Those gases are considered due to their impact on the greenhouse effect as well as climate change. Density functional theory (DFT) and first principles computation are utilized to evaluate the effect of Fe doping of MoSeS structure on the adsorption energy (Ea) and length (d), charge relocated between gas molecules and the structure (∆q), along with the density of states (DOS). The results reveal that Fe doping of MoSeS structure generates significant adjustments of the band gap so that the structure could be transformed from semiconductor into metallic or semimetallic. NO, NO2, and O2 gases exhibit favorable adsorption on doped structure with a maximum adsorption capacity for NO. Additionally, the doped structure exhibits selective adsorption for the gases with different adsorption energies. The doping of MoSeS dichalcogenide with Fe transition metal is a decent pathway to adjust its band gap along with its selectivity for gas adsorption.

The effect of silicon and Ti₅Si₃ films on the adhesion properties of the α-Al₂O₃/γ-TiAl interface and oxygen diffusion in TiAl was studied using the projector augmented-wave method within density functional theory. It was shown that the formation of intermediate silicide layers at the oxide–alloy interface can lead to a significant decrease in the oxygen diffusion coefficient. At the same time, adhesion at the oxide–silicide interface remains high, while for the silicide–alloy interface, the values of ∼2.26–2.80 J/m² typical for interfaces with metallic and metal-covalent bonds were obtained.

By means of ab initio density functional theory (DFT) calculations, we examined the surface electronic structure of the TbIr₂Si₂ antiferromagnet, which is distinguished by the out-of-plane alignment of Tb 4f moments and a high Neel temperature. We analyzed the interplay between the spin-orbit and exchange in- ´ teractions and their effect on the dispersion of surface states resided in the projected band gap around the M¯ point of the surface Brillouin zone, and compared our theoretical findings with low-temperature angle-resolved photoemission spectroscopy (ARPES) measurements.

This work is devoted to the study of phase equilibria in the BiPO₄–YPO₄–(nH₂O) system under mild conditions. It was shown that using the precipitation method leads to crystallization of the samples into the rhabdophane phase YPO₄ · nH₂O and the ximengite phase BiPO₄. Hydrothermal treatment of the samples at 160^◦C results in the gradual transformation of hexagonal yttrium phosphate with a rhabdophane-type structure into tetragonal xenotime YPO₄, and hexagonal bismuth phosphate with a ximengite-type structure into monoclinic bismuth phosphate (space group P 2₁/n). The transformation into the stable phases of xenotime and monoclinic bismuth phosphate is almost complete after 28 days of isothermal holding under hydrothermal conditions at 160^◦C. Moreover, the lower the content of the second component in samples containing both Bi and Y, the faster the structural transformation into the stable phase proceeds. A solid solution based on monoclinic bismuth phosphate with the composition Bi0.94Y0.06PO4 is formed in the system. Before disappearing, the rhabdophane-type phase represents a solid solution with the composition Y_0.8Bi_0.2PO₄ · nH₂O. The crystallite sizes of all phases increase with an increase in the bismuth content in the system.

Copper oxide (CuO) nanoparticles were obtained under solution combustion conditions using glycine as an organic fuel and a chelating agent at different redox ratios (f = 0.2, 1.0, and 1.6). The obtained powders were thermally treated at 300 ◦C for 30 min and characterized by Thermogravimetry differential thermal analysis (DTA/TG), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), and atomic absorption spectrometry (AAS). The electrochemical characteristics were determined by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The average crystallite sizes and specific surface areas of the obtained samples varied in the range from 4.8 to 18.6 nm and 14.4 to 78.4 m²/g. The largest specific surface area corresponds to the sample synthesized at f = 0.2, which also has the smallest particle size (4.8 nm). The electrochemical behavior of copper oxide nanopowders depends significantly on structural and morphological features. The excellent specific capacity of the microstructure of the CuO sample synthesized at a significant fuel deficiency (f = 0.2) is explained by its large surface area and large pore radius.

This paper is devoted to studies of the conversion mechanism of carbon-containing fuels on multicomponent catalyst with the composition of 1.9 wt. % Pt–Ce_0.75Zr_0.25O₂ (Pt/CZ) using in-situ Raman spectroscopy (RS) and catalytic activity measurements. It was found that during heating and transition from inert atmosphere to reducing conditions, oxygen escapes from the crystal lattice of the samples. This leads to formation of oxygen vacancies in the near-surface layer of the catalyst and increasing Ce³⁺ concentration by more than 20 % already at a temperature of 400^◦C. Meanwhile, when returning to the initial external conditions (temperature, gas mixture), a reversible process occurs. The use of Pt/CZ catalysts allows to obtain up to 35 vol % H₂ and about 25 vol % CO in syngas during dimethyl ether and dimethoxymethane partial oxidation. Thus, Pt/CZ catalysts are of particular interest as efficient catalysts for the conversion of hydrocarbons to synthesis gas, suitable for feeding SOFC stacks.

The La_0.9Sr_0.1Sc_0.9Co_0.1O₃-δ (LS) and La_0.9Sr_0.1CoO₃-δ (LC) phases and composite materials based on them were synthesized. There are data in the literature on the activity of pure or modified forms of LC in ammonia decomposition, but there are no data on the activity of the LS phase and LS–LC composites. Therefore, the stability and activity of LS–LC composites and initial LS and LC in ammonia decomposition were investigated. The best result in the decomposition of ammonia at 700◦C and WHSV of 60000 ml NH₃·g^-1_cat ·h^-1 shows LC – 99%, the worst LS – 80%. Under the same conditions, the activity of samples LC, 40LS–60LC and 50LS–50LC remains unchanged for 40 hours. It was found that during ammonia decomposition, the LC phase decomposes to form cobalt and La(OH)₃ nanoparticles, but the LS phase does not undergo significant changes, which is confirmed by X-ray diffraction, IR spectroscopy, Raman spectroscopy and TEM.

Water contamination from industrial effluents is a significant environmental challenge due to the presence of organic dyes. This study presents the development of self-cleaning nanocomposite membranes based on sulfonated tetrafluoroethylene and 2D graphitic carbon nitride (g-C₃N₄) nanosheets for efficient water purification. The membranes were synthesized using solution casting with 1 and 5 wt. % g-C₃N₄ as a photocatalytic filler. A comprehensive physicochemical characterization was conducted using XRD, FTIR, SEM, DRS, and adsorption tests. The photocatalytic performance was assessed through the degradation of methylene blue under visible light. Results show that membranes with 5 wt. % g-C₃N₄ exhibit enhanced adsorption efficiency (k = 0.0800 min^-1) and notable photocatalytic activity (k = 0.0083 min^-1), leading to effective dye removal and self-cleaning functionality. These findings highlight the potential of hybrid polymer-nanomaterial membranes for sustainable wastewater treatment. The proposed membranes offer a promising solution for removing hazardous organic pollutants while maintaining long-term operational stability.

Hydrophobic CsPbBr₃ perovskite quantum dots (PQDs) were synthesized via a ligand-assisted re-precipitation method with various antisolvents. A study was conducted to assess antisolvents influence on the properties of the synthesized PQDs. To enhance the stability of PQDs in polar media and possess surface functional groups for further conjugation with biomolecules, the surface of the nanoparticles was modified with 2 bromoisovaleric acid (Br-iVA), cetyl alcohol (CtA), and 3-aminopropyltriethoxysilane (APTES). PQDs modified with Br-iVA exhibited the highest stability in polar solvents and water, maintaining for up to 90 days.

Various applications and synthesis methods of quantum dots require reliable analytical methods to determine composition, colloidal stability, monodispersity, as well as to identify quantum dots. Therefore, their analysis is of great interest. As a rule, water-dispersible nanoparticles have a surface charge, which makes electrophoretic methods of analysis promising for characterising quantum dots (QDs). Hydrophilic CdTe, CdTe/ZnS, and multilayer CdTeSe/CdS/CdZnS/ZnS QDs were studied using capillary zone electrophoresis (CZE). A method for analyzing and characterizing colloidal QDs by CZE was developed, the influence of factors of the electrophoretic process on the parameters of QDs migration was studied and the conditions for QDs analysis were selected. Optimal conditions have been established for determining quantum dots with a minimum analysis duration and using a borate buffer containing surfactant as a background electrolyte. Since the synthesis of multilayer quantum dots is multi-stage, the developed analysis method can be used for express analysis and characterization of hydrophilic QDs obtained at each synthesis step. In this study, it was shown that by the type of electropherogram and the width of the peak corresponding to QDs, conclusions can be made about the heterogeneity of the synthesized samples in size, the efficiency of each stage of QDs synthesis and purification, and the processes of their degradation during storage.

The results of research on the influence of clinoptilolite zeolite, phosphorus-zeolite, and zeoliteorganic fertilizers on seed germination and growth of perennial legume grasses by laboratory phytotesting in grey forest soil are presented. It was found that as a result of filling the interpolymer complex with clinoptilolite zeolite, hydrogen bonds are formed between carbonyl groups of polyacrylamide and silanol groups of the mineral. The important role of the size factor in the influence of fertilizer on plant growth has been established. It is shown that mechanically activated clinoptilolite-rich rock (mechanical energy dose 2.4 kJ·g^-1) and the polyvinyl alcohol/polyacrylamide interpolymer complex resulting from mixing equivolume aqueous solutions with concentrations of 4 g·dL^-1, filled with 0.4 wt % mechanically activated clinoptilolite-rich rock (mechanical energy dose 3.8 kJ·g^-1), have a positive effect on germination and stem length of perennial legume grasses of meadow clover, eastern galega, and sand sainfoin in dark grey forest soil.

 Correction of affiliation of Maksim S. Plekhanov