bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin wave selection in an ensemble of laterally and vertically coupled iron-yttrium garnet microwaveguides
Authors: Khutieva A. B. , Akimova V. R. , Beginin E. N. , Sadovnikov A. V.
Published: April 2024

Numerical micromagnetic modeling used to study the modes of propagation of spin waves and processes of power transfer in the considered arrays of microwaves in the configuration corresponding to excitation in two central channels of one of the layers of surface and inverse bulk magnetostatic spin waves is conducted. It is shown that the proposed structure performs the functions of spatial-frequency signal selection, the efficiency of which depends on the mutual orientation of the submagnetization field and the direction of wave propagation.
Fabrication of GRIN microstructures by two-photon lithography
Authors: Soboleva I. V. , Bessonov V. O. , Fedyanin A. A. , Aparin M. D. , Baluyan T. G. , Sharipova M. I. , Sirotin M. A. , Lyubin E. V.
Published: April 2024

The method of two-photon lithography is used to fabricate GRIN microstructures. Test rectangular structures with sizes 25 × 25 × 3 micrometers were used with varying laser intensity by linear or gaussian distribution in one dimension. The resulting refractive index has been tuned in the range of 0.03. The suggested method can be applied to produce arbitrarily shaped 3D GRIN micro-optical elements.
Magnetic-controlled composite elastomer based on polydimethylsiloxane with a porous structure
Authors: Amirov A. A. , Kaminsky A. S. , Arkhipova E. A. , Cherkasova N. A. , Tovpinets A. O. , Leucine V. N. , Pyatakov A. P. , Zhivulin V. E. , Rodionova V. V.
Published: April 2024

Magnetic elastomers based on polydimethylsiloxane polymer with a filler of barium hexaferrite microparticles with a homogeneous and porous microstructure have been obtained. The microstructure, magnetic and mechanical properties of the obtained samples were studied. The filler leaching method used in the work makes it possible to obtain magnetic elastomers with a porosity of about 58%. It is shown that the porous microstructure leads to a significant decrease in the Young’s modulus of the samples from 0.63 MPa (homogeneous) to 27 kPa (porous) and doesn’t produce any significant changes in the magnetic properties of the sample.
Search for sources of solar cosmic rays in weak events
Authors: Bazilevskaya G. A. , Daibog E. I. , Logachev Yu. I.
Published: April 2024

Some of the weak solar proton events recorded by the Earth observer, in which protons with energy E 10 MeV were observed, are really particles accelerated by a shock wave in interplanetary space. They can be associated with a flare and a coronal mass ejection ten of hours before the observed proton event, which ensure the injection of particles into the process of their subsequent acceleration in interplanetary space.
Monitoring of heliosphere, magnetosphere and atmosphere via cosmic ray effects in August 2018
Authors: Kovalev I. I. , Olemskoy S. V. , Sdobnov V. E. , Dmitrieva A. N. , Shutenko V. V.
Published: April 2024

Using data of ground-level cosmic ray measurements on the neutron monitor network, along with data of Yakutsk muon telescope complex and muon hodoscope URAGAN (Moscow) uncorrected for temperature, we used modified spectrographic global survey method for an August 2018 event to split cosmic ray variations into components of primary, magnetospheric and atmospheric origin. Time evolutions of isotropic primary flux for different rigidities, pitch-angle anisotropy of cosmic rays, interplanetary magnetic field orientation were obtained, variations in geomagnetic cut-off rigidity in Irkutsk and average-mass temperature over charged components’ measurement sites were also shown.
Charge-sign dependence of cosmic-ray modulation by the PAMELA experiment
Authors: Mukhin P. , Mikhailov V. V. , Mikhailova A. V.
Published: April 2024

To study the solar modulation of cosmic-ray fluxes below 1 GeV, machine learning methods allowed obtaining the flux ratios of positrons and electrons with energies from 100 to 500 MeV, and the fluxes of electrons and protons with 1–1.7 GV rigidities from the PAMELA experiment for 2006–2016. The observed features of the data obtained and its comparison with the AMS-02 experimental data enable researching the charge-sign dependence of the modulation around the solar minimum in 2009 and the maximum in 2015.
First experiment at the Super Heavy Element Factory: new data from the 243Am + 48Ca reaction
Authors: Kovrizhnykh N. D. , Oganessian Yu. Ts. , Utyonkov V. K. , Abdullin F. Sh. , Dmitriev S. N. , Dzhioev A. A. , Ibadullayev D. , Itkis M. G. , Karpov A. V. , Kuznetsov D. A. , Petrushkin O. V. , Podshibiakin A. V. , Polyakov A. N. , Popeko A. G. , Rogov I. S. , Sagaidak R. N. , Schlattauer L. , Shubin V. D. , Shumeiko M. V. , Solovyev D. I. , Tsyganov Yu. S. , Voinov A. A. , Subbotin V. G. , Bodrov A. Yu. , Sabel’nikov A. V. , Khalkin A. V.
Published: April 2024

We presented the results of the series of experiments on the synthesis of Mc isotopes in the 243Am + 48Ca reaction performed at the new separator DGFRS-2 and cyclotron DC280 of the SHE Factory at FLNR JINR. There were registered 110 new 288Mc decay chains, 10 289Mc chains, and 4 287Mc chains. Alpha decay of 268Db with an energy of 7.6–8.0 MeV, half-life \(16_{{ - 4}}^{{ + 6}}\) h and α-branch \(51_{{ - 12}}^{{ + 14}}\% \) was registered for the first time together with a new spontaneously fissioning isotope 264Lr with a half-life of \(4.8_{{ - 1.3}}^{{ + 2.2}}\,\,{\text{h}}.\) The measured cross section of the 243Am(48Ca, 3n)288Mc reaction was \(17.1_{{ - 4.7}}^{{ + 6.3}}\) pb, which is the largest for known superheavy nuclei. A new isotope 286Mc was synthesized with a half-life of \(20_{{ - 9}}^{{ + 98}}\) ms and an α-particle energy of 10.71 ± 0.02 MeV. Spontaneous fission of 279Rg was first observed in one of the four new decay chains of 287Mc. The reaction excitation function was measured at six 48Ca energies in the range of 239–259 MeV, which led to the first observation of the 5n channel with a cross section of \(0.5_{{ - 0.4}}^{{ + 1.3}}\) pb. The decay properties of 20 previously known isotopes have been determined with higher accuracy.
Study of the 242Pu + 48Ca reaction at Super Heavy Element Factory
Authors: Ibadullayev D. , Utyonkov V. K. , Oganessian Yu. Ts. , Abdullin F. Sh. , Dmitriev S. N. , Itkis M. G. , Karpov A. V. , Kovrizhnykh N. D. , Kuznetsov D. A. , Petrushkin O. V. , Podshibiakin A. V. , Polyakov A. N. , Popeko A. G. , Sagaidak R. N. , Schlattauer L. , Shubin V. D. , Shumeiko M. V. , Solovyev D. I. , Tsyganov Yu. S. , Voinov A. A. , Subbotin V. G. , Bodrov A. Yu. , Sabel’nikov A. V. , Giniyatova Sh. G. , Kuterbekov K. A.
Published: April 2024

Experiments on the synthesis of isotopes of element 114 in the 242Pu + 48Ca reaction were carried out at a new gas-filled separator DGFRS-2 online to the DC-280 cyclotron of the Superheavy Element Factory at FLNR JINR. The decay properties of 286Fl and 287Fl, as well as their α-decay products, were refined. The possibility of the existence of isomeric states in successive α-decays of 287Fl is discussed. The maximum cross section of \(10.4_{{ - 2.1}}^{{ + 3.5}}\) pb was measured for the 242Pu(48Ca, 3n)287Fl reaction.
Charge exchange processes during carbon ion fragmentation at an energy of 300 MeV/nucleon: comparison with models of ion-ion interactions
Authors: Kulikovskaya A. A. , Abramov B. M. , Borodin Yu. A. , Bulychjov S. A. , Dukhovskoy I. A. , Krutenkova A. P. , Kulikov V. V. , Martemianov M. A. , Matsyuk M. A. , Turdakina E. N.
Published: April 2024

Experimental data are presented on the differential cross sections to produce 11Be, 12Be, and 12B isotopes at the carbon beam fragmentation with an energy of 300 MeV/nucleon in the FRAGM experiment conducted based on the ITEP-TWAС multipurpose accelerator complex. The obtained experimental data are compared with the predictions of the models of ion-ion interactions: binary cascade and quantum molecular dynamics model.
Simulation of tracking detector based on triple GEM chambers for the first physics run of the BM@N experiment
Authors: Baranov D. A.
Published: April 2024

The features and stages of simulation of triple GEM detector for the first physics run in the BM@N experiment in 2022 are presented. We described the procedure for electrostatic field map calculation based on the current configuration of the GEM detector. We also consider tool set required for detailed simulation of physics processes inside the GEM chamber and give some results obtained.
Similarity and distinctions of 58, 60Ni photodisintegration processes
Authors: Varlamov V. V. , Davydov A. I. , Orlin V. N.
Published: April 2024

Reliability of (γ, 1n) and (γ, 2n) reactions cross sections for 58, 60Ni obtained in experiments carried out on the beams of bremsstrahlung and quasimonoenergetic annihilation photons was investigated using objective physical criteria. It was found that data of the first type experiment do not satisfy those criteria and definitely are not reliable. At the same time there are serious doubts in reliability of the data obtained in the second type experiment. New partial photoneutron reaction cross sections on 58, 60Ni satisfying physical criteria of data reliability were used for analysis of characteristics of both isotope photodisintegration processes. It was obtained that for neighboring (differ in two neutrons) isotopes because of various type systematic uncertainties there are significant disagreements between evaluated and experimental cross sections of various reactions which for isotopes 58Ni and 60Ni are of significant different character. It was shown that the reasons are not only the differences in energy thresholds and absolute values of cross sections of the (γ, 1n), (γ, 1n1p) and (γ, 2n) reactions on 58Ni and 60Ni but significant differences in specific features of neighboring isotopes shell structure also.
Shift of the “coil–globule” transition in porous polymer films
Authors: Maksimov A. V. , Maksimova O. G.
Published: April 2024

Using the model of Gaussian subchains “beads on a thread”, the reduced parameters of the state equation for porous polypropylene films in various solvents are found. It is shown that to satisfy to experimental data, the coil-globule transition is shifted towards higher values of the Flory–Huggins interaction parameter.
Electric polarization due to Yafet–Kittel ordering in spinels
Authors: Motseyko A. V. , Ter-Oganessian N. V.
Published: April 2024

We show that the triangular Yafet–Kittel magnetic ordering in AB2X4 spinels, in which the sublattice A spins are split into two noncollinear sublattices, leads to the appearance of electric polarization, and thus the crystal becomes multiferroic. Calculation of the magnetic and magnetoelectric properties of MnCr2S4 considering single-ion anisotropy illustrates the proposed mechanism.
Switching processes in ferroactive solid solution 0.725NaNbO3–0.20KNbO3–0.075CdNb2O6
Authors: Moysa M. O. , Talanov M. V. , Andryushin K. P. , Shvetsova N. A. , Shvetsov I. A. , Rybyanets A. N.
Published: April 2024

The results of dielectric hysteresis loops and dielectric permittivity studying of 0.725NaNbO3–0.20KNbO3–0.075CdNb2O6 ceramics in strong (5–40 kV · cm–1) and weak (0–0.3 kV · cm–1) alternating electric field are presented. The parameters of the reversible and irreversible contributions to the dielectric permittivity are determined. Based on the Preisach model, a diagram of the density of domain switching is constructed. It is shown that the distribution function of domains over local coercive fields is characterized by a sharp peak, which indicates a high degree of homogeneity of the domain structure.
Dependence of the relaxation properties of polypropylene solutions on the concentration of organic solvents: molecular dynamics simulation
Authors: Egorov V. I. , Maksimova O. G.
Published: April 2024

The microscopic relaxation of polymer chains in organic solvents has been studied by the molecular dynamics method. The simulation was carried out for the mixtures of polypropylene with three different organic solvents (acetone, cyclopentane, acetonitrile). The dependence of the relaxation time and the glass transition temperature of the polymer on the mass fraction of the solvent is obtained.
Electron microscopy and electron energy loss spectroscopy of titanium nitride thin films in TiNx/La: HfO2 (Hf0.5Zr0.5O)/TiNx/SiO2
Authors: Suvorova E. I. , Uvarov O. V. , Klimenko A. A. , Chizh K. V.
Published: April 2024

The structure and properties of TiNx electrodes obtained by plasma-enhanced atomic layer deposition in the 20 nm TiNx/10 nm La: HfO2(Hf0.5Zr0.5O)/20 nm TiNx/1 μm SiO2 system have been studied by electron microscopy and electron energy loss spectroscopy. It is shown that the electrode material has a TiNxOy composition, the band gap width varies within 1.7–2.5 eV, the resistivity is 208 μOm cm and the value of the temperature coefficient of resistance (20–100°C) is equal to –31.4 ⋅ 10–6 1/K.
Evolution of the structure of shells of hollow submicron SiO2 particles during heat treatment
Authors: Zhokhov A. A. , Emel’chenko G. A. , Sukhinina N. S. , Masalov V. M. , Khodos I. I.
Published: April 2024

Hollow SiO2 particles of submicron size were synthesized and changes in the structures and morphology of their shells during heat treatment were investigated. The dependences of the shrinkage of silica shells on the annealing temperature of the particles were studied. It has been found that after annealing at 600°C, shells of hollow particles become non-porous and impermeable to liquid media.
Thermodynamic crisis during spontaneous boiling-up of superheated n-pentane in a vertical glass tube
Authors: Parshakova M. A. , Lipnyagov E. B.
Published: April 2024

The kinetics of boiling-up of superheated n-pentane in a glass tube was studied by high-speed video and fast acting pressure sensor. The top of the tube is sealed. It is shown that, as the threshold temperature is approached, the boiling-up of a superheated liquid is accompanied by significant pressure jumps and oscillations, and the formation of a vapor film can begin with self-organization in the near-wall layer of the liquid.
Dielectric and optical properties of gas hydrates and ice: ab initio simulation results
Authors: Yunusov M. B. , Khusnutdinoff R. M.
Published: April 2024

The dielectric tensors εik(ω), optical absorption spectra R(ω), reflection spectra a(ω) and the density of electronic states N(E) have been calculated for the lattices of gas hydrates with the structure sI and sH, as well as for ice Ih and III. The dependence of the dielectric permittivity on the type of guest molecules in the sI hydrate is considered.
Reflective properties of active layered media at second optical harmonic generation
Authors: Zakharova I. G. , Lysak Т. М. , Kalinovich A. A. , Chaykovskii D. A.
Published: April 2024

We studied the reflective properties of an active periodic medium with quadratic nonlinearity using numerical modeling based on the description of the generation of the second optical harmonic in the quasi-optical approximation. The model under consideration appears to be a system of four coupled equations for slowly varying amplitudes of forward and backward waves. Based on numerical simulation, the influence of the asymmetric Bragg coupling of counterpropagating waves at the fundamental frequency on the absorbing/generating and reflecting properties of the active medium is analyzed.
Few-cycle two-frequency spatiotemporal solitons in the absence of group velocity dispersion at one of the components
Authors: Koshkin K. V. , Sazonov S. V. , Komissarova M. V. , Kalinovich A. A.
Published: April 2024

The second harmonic generation by few-cycle pulses is studied when the group velocity dispersion coefficient is equal to zero at the fundamental or doubled frequency. Using numerical simulation, it is shown that in both cases, in the presence of a negative third-order dispersion, the formation of stable two-frequency spatiotemporal solitons is possible.
NaYbF4:Er luminescence anisotropy in a large ensemble and single nanoparticles
Authors: Shmelev A. G. , Mityushkin E. O. , Nurtdinova L. A. , Leontyev A. V. , Petrov D. N. , Zharkov D. K. , Nikiforov V. G.
Published: April 2024

The upconversion NaYbF4:Er nanorods were synthesized by the hydrothermal method at the temperature of 190°C for 24 h. The luminescence spectrum exhibits intense luminescence lines in the visible and near-IR ranges under 977 nm laser diode excitation. The polarization of the upconversion luminescence of a large ensemble of nanoparticles is isotropic. Considering the pronounced rod structure of nanoparticles, the presence of several subensembles with different polarization characteristics of the luminescence was assumed.
Influence of carbon nanotubes on the formation of shock electromagnetic waves
Authors: Belibikhin S. V. , Konobeeva N. N. , Belonenko M. B.
Published: April 2024

Based on the shortened Maxwell equations, for a nonlinear medium containing carbon nanotube of the semiconductor type, the formation of shock waves is studied. A classical nonlinear medium with cubic nonlinearity and dispersion is considered. It has been established that the introduction of carbon nanotubes stabilizes an ultrashort optical pulse and prevents the formation of shock waves. However, the pulse remains localized.
Effect of CO2 Additives on the Non-Catalytic Conversion of Natural Gas into Syngas and Hydrogen
Authors: Akhunyanov A. R. , Arutyunov A. V. , Vlasov P. A. , Smirnov V. N. , Arutyunov V. S.
Published: April 2024

Abstract—A kinetic analysis of the non-catalytic carbon dioxide reforming of CH4 has been carried out in the temperature range of 1500–1800 K under conditions of variable temperature behind the reflected shock wave. The stages of conversion of methane into synthesis gas, the characteristic time intervals corresponding to these stages, and the most important elementary reactions have been established. At the first stage, as a result of thermal pyrolysis, methane molecules are sequentially converted into ethane, ethylene, and then acetylene, the most stable hydrocarbon in this temperature range. At the second stage, acetylene is normally converted into CO and H2, being accompanied by the formation soot particles in the case of rich mixtures. The conversion of CO2 proceeds at the second and third stages, when CH4 conversion is almost complete. It occurs as a result of the interaction of CO2 molecules with H● atoms arising in the reacting system and leads to the formation of CO molecules and OH● radicals. Acetylene is predominantly consumed in the reaction with OH radicals. A high concentration of acetylene during methane reforming promotes the intensive formation of soot nuclei, for which acetylene makes the highest contribution to the rate of their surface growth. At the same time, acetylene itself is not a precursor of soot particle nuclei, which are mainly formed from \({{{\text{C}}}_{{\text{3}}}}{\text{H}}_{3}^{\centerdot }\) radicals.
Studying the Properties of Molecular Sites Produced from Gels Containing Layered 2D Silicoalumophosphates with Different SiO2/Al2O3 Ratio
Authors: Agliullin M. R. , Serebrennikov D. V. , Khalilov L. M. , Fayzullina Z. R. , Pavlova I. N. , Kutepov B. I.
Published: April 2024

Abstract—Crystallization of molecular SAPO-41 sieves from gels containing layered 2D silicoaluminophosphates with various SiO2/Al2O3 molar ratios (from 0.1 to 0.3). The effect of the presence of layered phases in gels on the chemical and phase composition, acid properties, and the characteristics of the porous structure of their crystallization products has been established. A method for the synthesis of SAPO-41 of high phase purity and degree of crystallinity is proposed. The catalytic properties in the hydromeasurement of n-hexadecane prepared on the basis of the obtained molecular sieves of Pt-containing catalytic systems have been studied.
Stereoselectivity of Acetylene Hydrochlorination over Supported PdCl2/С Catalysts
Authors: Krasnyakova T. V. , Nikitenko D. V. , Kobets K. D. , Krasniakova I. O. , Gogilchin A. S. , Bugaev A. L. , Mitchenko S. A.
Published: April 2024

The products of catalytic hydrochlorination of acetylene-D2 over palladium chloride complexes supported on activated carbon are a mixture of vinyl chloride stereoisomers resulting from syn- and anti-addition of the hydrogen chloride molecule to the triple bond. The reaction is accompanied by isomerization of primary trans-vinyl chloride into its cis-stereoisomer, but the characteristic isomerization times exceed significantly the duration of acetylene hydrochlorination. This fact allowed us to estimate the portion of products formed exclusively during the catalytic reaction, the difference in the effective activation energies of the syn- and anti-addition routes (~21 kJ/mol), and to demonstrate a monotonic increase in the part of the syn-addition product with increasing mass loading ω of the active metal, reaching saturation at ω 2 wt %.
Novel Two-Stage Method of Preparing Graphitic Carbon Nitride Doped by Chlorine for Photocatalytic Hydrogen Evolution and Photocurrent Generation
Authors: Zhurenok A. V. , Markovskaya D. V. , Potapenko K. O. , Sidorenko N. D. , Cherepanova S. V. , Saraev A. A. , Gerasimov E. Y. , Kozlova E. A.
Published: April 2024

In this work graphitic carbon nitride doped by chlorine was prepared by a two-stage technique at first. At the first stage melamine was hydrothermally treated with glucose, at the second stage the mixture of as-prepared melamine with ammonium chloride was calcined. The obtained samples were investigated by the set of methods: X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy, photoelectrochemical methods. All prepared photocatalysts was tested in the reaction of photocatalytic hydrogen production from basic solutions of triethanolamine. It was shown that the highest values of the catalytic activity and short-circuit current density were obtained over the photocatalyst preparing by calcination of the mixture containing 30% ammonium chloride and 70% melamine. The highest value of the catalytic activity was 1332 μmol h–1 g–1 and was more than the catalytic activity of carbon nitride preparing by the melamine calcination without another treatment in 22 times.
Ceria–Zirconia Supported Platinum Catalysts for Water Gas Shift Reaction: Influence of Support Composition
Authors: Gorlova A. M. , Pakharukova V. P. , Stonkus O. A. , Rogozhnikov V. N. , Gladky A. Y. , Snytnikov P. V. , Potemkin D. I.
Published: April 2024

The study is presented on the influence of the composition of a ceria-zirconia support on the structure and the activity in water gas shift reaction of platinum catalysts (Pt/Ce0.75Zr0.25O2 и Pt/Ce0.4Zr0.5Y0.05La0.05O2). The structure diagnostics of the samples were performed using high-resolution transmission electron microscopy, powder X-ray diffraction, CO chemisorption and X-ray atomic pair distribution function method. It was shown that the catalysts contain highly dispersed platinum particles not exceeding 2 nm in size. Platinum particles supported on Ce0.75Zr0.25O2 are smaller due to the higher specific surface area of the support. The catalysts Pt/Ce0.75Zr0.25O2 and Pt/Ce0.4Zr0.5Y0.05La0.05O2 proved to have similar efficiency while having the same platinum content. It was assumed that the catalysts supported on Ce0.4Zr0.5Y0.05La0.05O2 demonstrate a slightly higher turnover frequency per platinum surface atom, but it is likely compensated by the difference in the supported metal particle size.
Crown Ether Complexes with Alkaline Earth Metal Chlorides ‒ Catalysts for the Decomposition of Isopropylbenzene Hydroperoxide
Authors: Nurullina N. М. , Usmanova Yu. Kh. , Karalin E. A. , Elimanova G. G. , Kharlampidi Kh. E.
Published: April 2024

Kinetic and thermodynamic parameters of the decomposition of isopropylbenzene hydroperoxide in chlorobenzene in the presence of dibenzo-18-crown-6 ether (DBK) complexes with CaCl2, SrCl2, BaCl2 have been experimentally obtained. The catalytic activity of alkaline earth metal compounds decreases in the series SrCl2·DBK CaCl2·DBK BaCl2·DBK. The formation of intermediate intermediates in the metal‒complex-hydroperoxide system has been kinetically established. SrCl2·DBK forms the strongest and most ordered structures with isopropylbenzene hydroperoxide, which decay at the highest rates. The formation of intermediate intermediates has been confirmed using quantum chemical modeling.
Isobutane Dehydrogenation on CrOx/Al2O3 Nanoparticles, Prepared by Laser Synthesis in Various Gases
Authors: Baronskiy M. G. , Zaitseva N. A. , Kostyukov A. I. , Zhuzhgov A. V. , Snytnikov V. N.
Published: April 2024

The catalytic properties of nCrOx/Al2O3 nanoparticles (n = 4.8 ± 0.05 wt %) tested in the isobutane dehydrogenation reaction which were obtained by laser synthesis in various gases are studied in detail for the first time. Laser synthesis of 4.8% CrOx/Al2O3 nanopowders was carried out by the vaporization of 5.0% Cr : α-Al2O3 ceramic targets using cw CO2 laser irradiation in an inert, oxidizing and reducing gaseous environment in a vaporization chamber: in an Ar medium; Ar with addition of O2, H2 and CH4 at concentrations of 20, 30, and 13 vol. %, respectively. The role of the gas medium during the synthesis of 4.8% CrOx/Al2O3 nanopowders in their catalytic properties (activity, selectivity, conversion, and stability in the reaction) was determined. A comprehensive study of the physicochemical properties of the obtained nanocatalysts was carried out using XRD, TEM, UV-Vis DRS, and Raman techniques. According to XRD data the phase composition is predominantly consists of γ-Al2O3 with the beginning of the transition to δ-Al2O3. According to the TEM results, the shape of nanoparticles is spherically symmetric with an average particle size dm = 15 nm. Using the UV-Vis DRS method, charge states of Crq+ (q = 3, 6) in different coordination (Cr6+(Td) and Cr3+(Oh)) and its different ratios depending on the gas atmosphere used in the process of laser vaporization were revealed in the obtained 4.8% CrOx/Al2O3 nanopowders. Nanosized 4.8% CrOx/Al2O3 catalyst prepared in an atmosphere (Ar + H2) demonstrated the highest values of isobutane conversion (39%) and isobutylene selectivity (90.7%); the lowest corresponding values of conversion (18.8%) and selectivity (85.6%) were typical for the sample obtained in the atmosphere (Ar + CH4). Thus, the most active and selective in the isobutane dehydrogenation reaction was the 4.8% CrOx/Al2O3 nanocatalyst synthesized in the (Ar + H2) medium, and the presence of methane during vaporization led to the initial surface carbonization, which prevents the access of reacting molecules to it.
Decomposition and O3-Catalytic Oxidation of n-С4Н10
Authors: Bokarev D. A. , Paramoshin I. V. , Kanaev S. A. , Stakheev A. Y.
Published: April 2024

The activity of transition metal oxides (V, Cr, Mn, Fe, Co, Ni, Cu, Zn) deposited on γ-Al2O3 in the ozone decomposition reaction has been studied. The catalytic characteristics of samples with high (NiO/Al2O3), low (Cr2O3/Al2O3) and intermediate (MnOx/Al2O3) activity in ozone decomposition were studied in the process of ozone-catalytic oxidation (OZCO) of butane. The obtained results allow us to conclude that the optimal activity of transition metal oxide in the decomposition of O3 is of key importance in the OZCO process. At a low rate of ozone decomposition, the oxidation of hydrocarbons is limited by the rate of formation of atomic oxygen, in the case of too high - the conversion of hydrocarbons is reduced due to the “inappropriate” process of recombination of atomic oxygen. The best catalytic characteristics in the oxidation of h C4H10 have been established for a catalyst based on Mn oxide, which has optimal activity in the decomposition of O3.
Bimetallic Heterogeneous Catalysts for the Oxidation of Sulfur-Containing Compounds with Hydrogen Peroxide
Authors: Gul O. O. , Polikarpova P. D. , Akopyan A. V. , Anisimov A. V.
Published: April 2024

Bimetallic heterogeneous catalysts based on SBA-15 containing molybdenum and iron oxides were studied in the oxidation reactions of model mixtures of organosulfur compounds. Iron additive (in the form of iron(III) oxide) in the amount of 0.05 wt % to the catalyst 5%Mo/SBA-15 turns out to be the most effective. The catalysts were confirmed by a complex of physicochemical methods: low-temperature adsorption-desorption of nitrogen, X-ray phase analysis, transmission electron microscopy, X-ray photoelectron spectroscopy. The influence of the main oxidation parameters (reaction time, temperature, composition and amount of catalyst, amount of oxidizer) on the conversion of dibenzothiophene as a component of the model mixture weas investigated. Optimal oxidation conditions that allow to achieve total transformation of the substrate were selected: H2O2 : S = 2 : 1, 0.5 wt % of the catalyst FeMo/SBA-15, 60 min, 60°C; catalysts can be used for at least 5 cycles without loss of activity during their intermediate washing from oxidation products.
Mathematical Modeling of CO2 Reforming of Methane with Reverse Water Gas Shift Reaction
Authors: Rahimi Ahmad Reza , AleEbrahim Habib , Sohrabi Morteza , Nouri Seyed Mohammad Mahdi
Published: April 2024

Synthesis gas is the cornerstone of many chemical processes for manufacturing a broad range of petrochemical products. In this work, a mathematical model was developed for investigation of the CO2 reforming of methane in a catalytic packed bed reactor. To simulate the reformer, a pseudo homogenous two-dimensional mathematical model was developed and the resulting nonlinear second order partial differential equations were solved using the finite difference method. It was assumed that equilibrium reverse water gas shift reaction always takes place in the reactor to adjust H2/CO ratio (≤1). The effect of operating conditions, including bulk density, porosity, inlet gas and wall temperature, reactor diameter, total molar flow of gas and inlet CH4/CO2 ratio on the reactor performance were investigated. Finally, the study investigated the effect of H2/CO ratio on the outlet synthesis gas product at the range of 0.7–1. The validity of the model was investigated and the deviation between the model results and the experimental data was acceptable.
Support Effect on the Characteristics of Mn Supported Catalysts in the O3 Catalytic Oxidation of VOCs
Authors: Bokarev D. A. , Paramoshin I. V. , Rassolov A. V. , Kanaev S. A. , Bragina G. O. , Stakheev A. Yu.
Published: April 2024

Catalytic characteristics of Mn-catalysts supported on different (SiO2 and BEA zeolite) were compared in the ozone decomposition and ozone-catalytic oxidation (OZCO) of VOCs using n-butane as the model compound. The parent SiO2 did not show any activity; therefore the characteristics of Mn/SiO2 are determined by the catalytic properties of the supported MnOx oxide. In contrast to SiO2, BEA zeolite demonstrates significant catalytic activity, though at a temperature by 50°C higher than Mn/BEA. The data obtained allow us to conclude that the catalytic characteristics of Mn/BEA at 30–100°C are determined by the Mn component of the catalyst. At higher temperature the catalytic properties of BEA can significantly affect the course of the OZCO process. The zeolite carrier improves hydrocarbon conversion at 100–200°C and decreases the amount of ozone required for the OZCO process over Mn/BEA.
Distinguishing between Linear and Non-Linear (Cooperative) Substrate Activation Mechanisms in the Sonogashira Reaction under “Ligand-Free” and “Copper-Free” Conditions
Authors: Larina E. V. , Kurokhtina A. A. , Lagoda N. A. , Schmidt A. F.
Published: April 2024

The results are presented on the comparative studies of the differential selectivity patterns in the Sonogashira reaction with a pair of competing aryl acetylenes in the “ligand-free” and “copper-free” conditions when varying the nature and concentration of aryl halides and base. The revealed sensitivity of the differential selectivity of competing aryl acetylenes to aryl halide nature unambiguously indicated that the substrates were activated through linear mechanism from kinetic view. An absence of any influence of the nature and concentration of the base on the differential selectivity of competing aryl acetylenes indicated the irreversible character of the step of their activation.
The Radical-Chain Oxidation of Tetrahydrofuran Inhibited by Tocopherol and Ascorbic Acid
Authors: Yakupova L. R. , Migranov A. R. , Nasibullina R. A. , Safiullin R. L.
Published: April 2024

The effect of ascorbic acid and α-tocopherol on the radical chain oxidation of tetrahydrofuran was studied at a temperature of 309 K. The reaction was initiated by 2,2'-azo-bis-isobutyronitrile. The process rate was monitored by the oxygen absorption. The rate constant of the tetrahydrofuran peroxyl radical reaction with α-tocopherol were measured k7 = (2.9 ± 0.6) × 105 l mol–1 s–1. The effect of an aqueous solution ascorbic acid on the oxidation rate of tetrahydrofuran was studied. The rate constant of the tetrahydrofuran peroxyl radical reaction with ascorbic acid were measured k7 = (10.2 ± 1.0) × 104 l mol–1 s–1. The effect of ascorbic acid on the tetrahydrofuran oxidation inhibited by α-tocopherol is considered. It has been shown that when both inhibitors are used together, the induction period is equal to the sum of the induction periods of individual compounds. The effective inhibition rate constant in this case is equal to k7 = (2.5 ± 0.5) × 105 l mol–1 s–1.
On Possibility of the Development of Instability of the Surface of the Dome of a Rising Bubble
Authors: Meshkov E. E. , Mokretsov R. V. , Novikova I. A. , Sedov S. Yu. , Smagin I, R.
Published: April 2024

The results of experiments on the study of stability of the dome of a water bubble rising through a salt solution are presented. The experimental results are obtained using the PLIF method by recording the flow in the plane that coincides with the axis of symmetry of the bubble, The experiments demonstrate the possibility of the development of instability in the vicinity of the pole of the dome of such a bubble in accordance with the previously published results of computational simulation.
Motion of a Piston Separating Magnetic and Non-Magnetic Fluids in a Magnetic Field
Authors: Volkova U. V. , Merkulov D. I. , Kalmykov S. A. , Pelevina D. A. , Naletova V. A.
Published: April 2024

The pumping of non-magnetic fluid by a dosing pump that is based on a magnetic fluid with an immersed body made of a magnetizable material is studied theoretically and experimentally. The process of fluid pumping in an applied vertical uniform magnetic field is investigated. The time dependences of the rise of the piston between the magnetic and non-magnetic fluids are calculated and measured in constant and stepwise magnetic fields. A good agreement between theory and experiment is obtained. The dependence of the rise time of the piston on the magnitude of the constant magnetic field is calculated. The motion of piston is theoretically investigated after the magnetic field is switched off.
Using the Wave Propulsors in a Small-Waterplane-Area-Twin-Hull Boat
Authors: Prokofiev V. V. , Arkhangelsky E. A. , Boyko A. V. , Filatov E. V.
Published: April 2024

The efficiency of two types of wave propulsors (WPs) (a swinging spring-loaded wing WPand a direct-flow WP) is experimentally studied on a model of a small-waterplane-area-twin-hull(SWATH) boat. The NACA0015 airfoil was used as an operating element of both the swinging and thedirect-flow WPs. In the case of a direct-flow WP, the flat airfoil was rigidly fixed relative to the boathull with a chord inclination of 30. The operating efficiency of the wave propulsors is studied forwaves of various lengths depending on the draft of the SWATH boat hulls, and in the case of a swingingspring-loaded wing WP, also on the submergence depth of the propulsor. Using the results of towingtests, the thrust force of a direct-flow WP is estimated under various operating conditions. It is foundthat with increase in the submergence depth of the boat hulls, the efficiency of the direct-flow WPincreases, while the efficiency of the swinging WP decreases, however, it largely retains its operability,provided that the WP operating element remains at the optimal depth close to the water surface.
Fluid Flow to a Well through a Radial Hydraulic Fracture in a Porous Medium at Constant Flow Rate
Authors: Anosova E. P. , Nagaeva Z. M. , Shagapov V. Sh.
Published: April 2024

The problem of fluid withdrawal from a reservoir into a well or injection of fluid from a well into a reservoir in the presence of a hydraulic fracture perpendicular to the wellbore is considered in the constant flow rate regime. Analytical solutions that describe the evolution of pressure in the fracture at a constant reservoir-to-well fluid flow rate are obtained. Approximate solutions are constructed using the method of successive change of stationary states (SCSS). A comparison of the numerical results of the exact and approximate solutions shows that these solutions are almost identical. The influence of the reservoir features of the stratum and fracture on the evolution of pressure in the fracture and well is analyzed.
Lift Airfoils Close to the Airfoils in a Flow with the Maximum “Critical” Mach Numbers
Authors: Kraiko A. N. , Shapovalov V. A.
Published: April 2024

The lift airfoils close to the airfoils optimal with respect to the critical Mach numbers М* of two-dimensional bodies optimal with respect to М* are constructed using the direct method. Their almost zero wave drag coefficients сх remain the same not only at the free-stream Mach numbers М0 which are lower than М* but also at М0 perceptibly higher than М*. These new lift airfoils differ from the supercritical lift airfoils whose сх grow extremely rapidly when М0 becomes higher than the designed values. At identical thicknesses and М0 = М* the supercritical lift airfoils implement the greater lift coefficients су. However, due to the difference in the behavior of сх at М0 which are higher than the designed ones, the lift-drag ratio of the supercritical airfoils can become lower for the ratio of су not to сх, but even to the coefficient of total drag.
Gas Dynamic Models of the Interaction between the Solar Wind
Authors: BARANOV V. B.
Published: April 2024

Gas dynamic models of the interaction between the solar wind and cometary atmospheresare considered. Interest in the development of such models arose sharply after the beginning of the investigations of comets with the use of spacecraft launched at distances close to their surfaces. The instruments on this spacecraft gave the possibility to investigate experimentally the parameters of gas flow out from the cometary surfaces when the comets approach the Sun and its interaction with the solar wind plasma flow, which could not be made using only the spectral photometry. The beginning of such studies was started by almost instantaneous approaching of several space probes to Halley’s Comet on March 1986. Only after 28 years, the Rosetta spacecraft launched by the European Space Agency (ESA) along a complex trajectory have approached comet Churyumov–Gerasimenko and, maneuvering in the neighborhood of this comet during more than two years, it, in particular, have investigated the interaction of the cometary atmosphere and the solar wind
Calculation of the Stress-Strain State of a Polymer Composite in a Direct Electric Current Field
Authors: Lyukshin P. A. , Lyukshin B. A. , Panin S. V. , Bochkareva S. A.
Published: April 2024

In electrically conductive composites placed in an electric field, heat is released and nonuniform temperature fields are formed. This circumstance, in turn, induces strains and stresses in such composites. The article solves a sequence of unrelated boundary value problems: electrical conductivity in a field of direct electric current, thermal conductivity, thermoelasticity. It is shown that when an electric current flows in copper-graphite and copper-filled polymer composites, displacements, deformations, and stresses occur even in the case when the components of the composite do not have a piezoelectric effect.
Optimization of the Processes of Attenuation of Transverse Movements of a Trailer Following a Tractor
Authors: Smirnov A. S. , Muravyov A. S.
Published: April 2024

The article considers the issues of optimizing the processes of attenuation of the transverse movements of the trailer, which is attached to a tractor moving at a constant speed with the help of a hinge and taking into account the compliant clutch. As an optimization criterion characterizing the efficiency of this attenuation, the maximization of the degree of system stability is taken. In this case, the distance from the center of mass of the trailer to the point of its adhesion to the tractor acts as an optimized parameter. A detailed analytical solution of the problem is carried out, during which the optimal curve on the plane of dimensionless parameters is determined, which consists of several sections and is located in the region of motion stability. Visual graphic illustrations are given, explaining the meaning of the found solution and its main features. In addition, the obtained results are compared with the variant of the location of the center of mass of the trailer exactly in the middle between the point of its coupling with the tractor and the axle of the wheelset, and an assessment is made of the effectiveness of the obtained optimal solution. The conclusions made in the work are not only of theoretical interest, but can also find some practical application.
Determination of Dissipative Characteristics for Solving Problems of Dynamic Loading of Elastic Structures Using a Modal Approach
Authors: Bondarenko A. Yu. , Likhoded A. I. , Sidorov V. V.
Published: April 2024

A method is proposed for solving non-stationary dynamic problems with complex elastic moduli or stiffness matrices, which makes it possible to take into account the local dissipative properties of structural elements. It is shown that in synthesized structures, even with significantly different dissipative properties, the dynamic behavior and loading parameters at resonant frequencies are determined by single integral logarithmic decrements obtained by mass-energy averaging of the dissipative properties of structures. Two concepts for estimating the integral quality factors and logarithmic vibration decrements of structures with different dissipative properties are proposed, one of which is based on the physical features of resonant phenomena in mechanical systems, and the second is based on the analysis of the behavior of damped fundamental solutions of the corresponding homogeneous equations. The coincidence of the integral logarithmic decrements obtained on the basis of different concepts makes it possible to solve non-stationary problems for structures with different dissipative properties by expanding the kinematic parameters in terms of natural vibration modes (modal method). The results of calculations of the dynamic behavior of structures with different dissipative properties are demonstrated on model problems.
Spatial Oscillations of a Pipeline with Vibrating Supports
Authors: Utyashev I. M. , Shakiryanov M. M.
Published: April 2024

Spatial oscillations of a section of a pipeline with a liquid contained in it during the translational vibrational movements of the supports are investigated. Oscillations of both supports occur with equal amplitudes, frequencies and phases. Pipe deformations associated with the exit of its axis from the bending plane are assumed to be small. The interactions of internal constant pressure and changes in the curvature of the axial line, longitudinal and circumferential deformations of the pipe are taken into account. Its flexural-rotational vibrations are described by a system of two non-linear differential equations. By applying the Bubnov-Galerkin method, this system is reduced to the Cauchy problem, which is then solved numerically by the Runge-Kutta method. In the case of small bending and angular motions of the pipe, a comparison of the analytical and numerical solutions is given. An analysis is given of periodic and non-periodic oscillations of steel, titanium and composite pipes, for which, in particular, frequency spectra and Poincare mappings are constructed.
On the Stability of Stationary Solutions of the Equations of Motion of the Goryachev–Sretensky Gyrostat
Authors: Kosov A. A.
Published: April 2024

The equations of motion of the Goryachev–Sretensky gyrostat are studied. It has been established that one component of the angular velocity vector oscillates with zero average value on all solutions outside the set of zero level of the area integral. All stationary solutions are found, including two states of rest and two parametric families of permanent rotations. Using Chetaev’s method of integral connectives, sufficient conditions for the stability of stationary solutions are obtained. Based on the analysis of the roots of the characteristic equation, instability conditions were obtained. The possibility of gyroscopic stabilization due to the moment of circular-gyroscopic forces under certain conditions has been established.
On the Estimation of the Sensitivity of the Coefficients of Models for Inhomogeneous Solids
Authors: Vatulyan A. O. , Yurov V. O.
Published: April 2024

The problem of determining the characteristics of the sensitivity of inhomogeneous isotropic elastic solids with respect to three functions characterizing the inhomogeneity - Lame coefficients and density - is considered. The corresponding boundary value problems are formulated, equations for determining the sensitivity are obtained. An example is presented for a cylindrical rod in the analysis of longitudinal and bending oscillations, the sensitivity to changes in Young's modulus and density is analyzed. Using the iterative algorithm and the A.N. Tikhonov's regularization method, a number of inverse problems were solved to determine these characteristics for monotone and non-monotone laws of their change, and the results of computational experiments are presented. The norm of the difference between the exact and reconstructed solutions is analyzed. Recommendations are given for choosing the most efficient frequency range for sounding from the point of view of reconstruction.
Coupled Thermoelasticity of Hemitropic Media. Pseudotensor Formulation
Authors: Murashkin E. V. , Radaev Yu. N.
Published: April 2024

The present paper deals with the problem of deriving the constitutive equations for the micropolar thermoelastic continuum GN-I in terms of the standard pseudotensor formalism. In most cases, the pseudotensor approach is justified in modeling hemitropic micropolar solids, the thermomechanical properties of which are sensitive to mirror reflections of three-dimensional space. The requisite equations and notions from the theory of pseudotensors are revisited. General thermodynamic approaches are used, entropy and energy balance equations are discussed. The weights of the main thermomechanical pseudotensors are established. In a linear approximation, the constitutive equations of the hemitropic micropolar thermoelastic continuum (GN-I) of the first type are derived. A coupled system of differential equations of heat conduction and dynamic equations of the micropolar thermoelastic continuum GN-I is obtained.