bluuebunny/crossref_metadata_2025 huggingface dataset:
Room temperature ferromagnetism of a crystalline semiconductor compound Hg1 – xFexSe at extremely low concentration of impurity iron atoms (x ≤ 0.06 at %)
Authors: Govorkova T. E. , Okulov V. I. , Pamyatnykh E. A. , Gaviko V. S. , Surikov V. T.
Published: April 2024

On the single crystals of Hg1 – xFexSe (х ≤ 0.06 at %) with an extremely low concentration of the impurity iron atoms at room temperature (T = 300 K), high-temperature ferromagnetism of a new type in a impurity donor electron system was experimentally discovered.
Time-dependent photoconductivity in iron doped ZnSe crystals
Authors: Storozhevykh M. S. , Kalinushkin V. P. , Uvarov O. V. , Chegnov V. P. , Chegnova O. I. , Yuryev V. A.
Published: April 2024

We investigated photoconductivity in ZnSe crystals doped with iron by thermal diffusion in wavelength range 470–5000 nm at the temperature of 77 and 300 K. The samples show high photoconductivity in the visible region. The effects of long-term growth and relaxation of the photocurrent were discovered as well as the dependence of time of the photocurrent growth and relaxation on the wavelength of exciting radiation, its power and the voltage applied to a sample. The effect of quenching of residual photoconductivity under the irradiation in the range 850–940 nm was observed.
Particle-in-Cell simulation of cosmic ray acceleration in fast blue optical transients
Authors: Romansky V. I. , Bykov A. M. , Osipov S. M.
Published: April 2024

Results of Particle-in-Cell modelling of cosmic ray acceleration in sub-relativistic shocks (with speed about 0.3 speed of light) are presented. Synchrotron and Inverse Compton radiation from FBOT CSS161010 are calculated using particle distributions, obtained from PIC simulation. Source parameters are evaluated via fitting modeled radiation with observations.
On the study of the space metrics signature from correlations of particles in hadron interactions
Authors: Mukhamedshin R. A.
Published: April 2024

Long-range near-side “ridge” effect discovered by the CMS Collaboration at the LHC, and the coplanarity of subcores in gamma-ray-hadron families, can be reproduced in the framework of the coplanar generation of the most energetic hadrons in hadron interactions, explained, in particular, by the hypothesis of change of the signature of the metric of the space-time continuum, namely, the transformation of the basic three-dimensional state into two-dimensional one (3D ↔ 2D). A method is proposed for experimental verification of this hypothesis by studying the azimuthal correlations of particles in hadron interactions.
Solar relativistic electrons and protons on October 28, 2021 (GLE73)
Authors: Struminsky A. B. , Grigorieva I. Yu. , Logachev Yu. I. , Sadovskii A. M.
Published: April 2024

The proton event of October 28, 2021, which was accompanied by the first in the current 25th cycle and the 73rd in the history of observations, a ground-based enhancement in the intensity of cosmic rays (GLE73), is considered. The development of the parent flare lasted more than 10 min against the background of the highest energy release simultaneously creating the conditions both for acceleration of the coronal mass ejection (CME) and acceleration of charged particles to relativistic energies. The similarity of time intensity profiles of relativistic electrons and protons in the Earth’s orbit indicates a stochastic mechanism of their acceleration. The X1.0 eruptive flare on October 28, 2021, is similar in hard X-ray emission to the M5.1 flare on May 17, 2012 (GLE71). The relatively late start of the increase in the fluxes of relativistic electrons and protons in the Earth’s orbit compared to the GLE71 event is explained by the location of the flare on October 28, 2021 (S26W05) and the southward launch of the CME.
Effect of pressure and ventilation in the experimental hall on the background events count rate of the LVD detector
Authors: Agafonova N. Yu. , Ashikhmin V. V. , Dobrynina E. A. , Enikeev R. I. , Filimonova N. A. , Shakiryanova I. R. , Yakushev V. F.
Published: April 2024

In the LVD experiment (Gran Sasso, Italy), variations in the counting rate of detector background pulses associated with the injection of radon from the rock into the experimental hall are studied. We present dependences of changes in atmospheric pressure on the surface and in the experimental hall of the setup, as well as variations in the counting rate of LVD events associated with changes in radon concentration.
Photoproton reactions on molybdenum
Authors: Remizov P. D. , Zheltonozhskaya M. V. , Chernyaev A. P. , Zolotov S. A. , Yatsenko V. N.
Published: April 2024

The yields of (γ, p)-reactions for bremsstrahlung γ-quanta with boundary energies of 20, 40, and 55 MeV on a natural mixture of molybdenum isotopes targets were measured as well as the activity of the resulting 91m, 95mg, 96, 97Nb isotopes. The weighted average yields of these isotopes formed in (γ, p)-reactions on molybdenum were measured for the first time. The experimental values were compared with the theoretical yields calculated using the TALYS1.96 program code and the method of the consideration of the giant dipole resonance isospin splitting.
Heavy-ion physics with Compact Muon Solenoid detector
Authors: Petrushanko S. V.
Published: April 2024

Recent results on heavy-ion physics at the LHC (CERN) by the Compact Muon Solenoid (CMS) collaboration are analyzed. The tests of quark-gluon plasma carried out with the CMS detector provide valuable information about the behavior of matter in the extreme regime of very high energy nucleus-nucleus collisions.
Proton formation at absorption of π–-meson in a “live” silicon target
Authors: Gurov Yu. B. , Evseev S. A. , Leonova T. I. , Rozov S. V. , Sandukovsky V. G. , Chernyshev B. A.
Published: April 2024

The spectra of protons were measured at the absorption of stopped π–-mesons in “live” target—analog of the 28Si target. Based on the data obtained, it was possible to isolate the process without secondary interactions and obtain the spectrum of primary protons from the act of pion absorption on an intranuclear pp pair.
Study of tagged neutrino beam characteristics at the U-70 accelerator
Authors: Novoskoltsev F. N. , Sinyukov R. Yu. , Sokolov A. A.
Published: April 2024

The method of tagged neutrino beams is considered, based on the reconstruction of the kinematics of π+ → µ+νμ decay of the parent particle one can accurately recovers the momentum and type of the produced neutrino. We described the technique of the π+ parent particle beam formation on the U-70 accelerator (Protvino) channel. Also, the calculated characteristics of the corresponding beam are given.
Magnetic properties of the excited states of 156Gd
Authors: Usmanov P. N. , Vdovin A. I. , Yusupov E. K. , Nematjonov Sh. R.
Published: April 2024

Theoretical calculations within the framework of a phenomenological model with Coriolis mixing of states of low-lying positive-parity rotational bands were performed for 156Gd. The Coriolis interaction allows to explain the observed non-adiabaticity effects in the properties of the excited states. Reduced probabilities of the M1 transitions B(M1) and multipole mixing coefficients \(\delta ({{E{\text{2}}} \mathord{\left/
{\vphantom {{E{\text{2}}} {M{\text{1}}}}} \right.} {M{\text{1}}}})\) for transitions from vibrational states were calculated. The behavior of the probabilities of M1 transitions from the mixing states as a function of the total angular momentum was studied. The agreement of the theoretical results with experimental data is, in the whole, satisfactory.
Proton and deuteron polarimetry at Nuclotron–NICA
Authors: Terekhin A. A. , Ladygin V. P. , Isupov A. Y. , Volkov I. S. , Reznikov S. G. , Gurchin Y. V. , Tishevsky A. V. , Legostaeva K. S.
Published: April 2024

Extensive experience has been accumulated in deuteron and proton beam polarization measurements as well as in the simulation of the pp-, pd- and dp-elastic scattering up to 1 GeV/nucleon for polarimeter upgrade at the Nuclotron Internal Target Station. Further development of the pp-, pd- and dd-colliding beams polarimetry at NICA is discussed. The first results of the simulation of dd-elastic scattering at the total energy 4.22 GeV are presented.
Partial photoneutron reaction cross sections in experiments with bremsstrahlung
Authors: Varlamov V. V. , Davydov A. I. , Orlin V. N.
Published: April 2024

The analysis of reliability of experimental partial photoneutron reaction cross sections of the reactions (γ, 1n) and (γ, 2n) obtained in experiments on the beams of bremsstrahlung was carried our using the objective physical criteria. In this type of experiments partial reaction cross sections were obtained using the procedure of neutron yield cross section σ(γ, xn) corrections calculated on the base of statistical theory. It was found out that in the cases of 59Co, 58,60Ni, 112, 114, 119Sn reaction cross sections obtained using that procedure do not satisfy the physical criteria of data reliability and therefore are not reliable. At the same time in the cases of 127I, 165Ho и 181Ta one has not any doubts in the data obtained reliability.
The effect of micro-deformations created by illumination on the temperature dependence of the mobility of nonequilibrium non-thermalized charge carriers in media without a center of symmetry
Authors: Magomadov R. M. , Delmikhanov R. R.
Published: April 2024

It is shown that the energy of nonequilibrium nonthermalized holes in ZnS crystals with a cubic unit cell does not depend on temperature. The nature of the temperature dependence of the nonequilibrium nonthermalized holes mobility in ZnS crystals depends on the average relaxation time upon scattering by ions and neutral impurity atoms, dislocations, and microstrains.
Relaxation processes of high-molecular hydrocarbons after high-power ultrasonic exposure
Authors: Makarev D. I. , Reznichenko A. N. , Shvetsova N. A. , Rybyanets A. N.
Published: April 2024

We studied the effect of high-intensity ultrasonic treatment on the rheological characteristics of high-molecular hydrocarbons. The dependences of the change in their kinematic viscosity on frequency in the range from 15 to 87 kHz are presented at a constant intensity and duration of ultrasonic exposure, as well as on the intensity of ultrasonic exposure at a constant frequency and duration. The processes of relaxation of the kinematic viscosity of these substances after ultrasonic treatment have been studied.
Piezoelectric relaxation in piezoceramics in weak electric fields
Authors: Shvetsov I. A. , Shvetsova N. A. , Petrova E. I. , Makarev D. I. , Rybyanets A. N.
Published: April 2024

We study the processes of piezoelectric relaxation that occur in piezoelectric ceramics under the influence of weak constant electric fields. Precise measurements of the piezoresonance spectra of the ferroelectric ceramics of the PZT system at various directions of the applied constant electric field and polarization were performed using the method and program for the analysis of piezoelectric resonance for the radial and thickness resonant vibration modes of piezoceramic disks. A qualitative analysis of the time dependences of the real and imaginary parts of the piezoelectric constants of the studied piezoceramic disks obtained because of mathematical processing of sequentially measured piezoresonance spectra was carried out, and a physical interpretation of the results was proposed.
Morphology of surface aerosol particles in Moscow via scanning electron microscopy
Authors: Gubanova D. P. , Sadovskaya N. V. , Iordanskii M. A. , Avilov A. S. , Minashkin V. M.
Published: April 2024

The morphology and composition of aerosol particles in the surface Moscow atmosphere have been studied by scanning electron microscopy and X-ray spectral microanalysis. The results are interpreted considering seasonal, synoptic, and meteorological conditions. The main morphological types of particles of natural and anthropogenic origin are revealed.
Photonics of plant chloroplasts
Authors: Bukhanov E. R. , Volochaev M. N. , Pyatina S. A.
Published: April 2024

It is shown that the features of light propagation in plant leaves depend on the long-range ordering in chloroplasts and spectral characteristics of pigments. It has been established that, with regard of the dispersion of the chlorophyll absorption spectrum, the photonic density of states increases and the spectral peak shifts to the effective photosynthesis wavelength range, which enhances the probability of the photosynthesis processes.
The problem of description of relaxation modes in the dielectric spectroscopy
Authors: Volkov A. A. , Chuchupal S. V.
Published: April 2024

The problem of a model choice for description of broad absorption–dispersion relaxation bands in the dielectric spectroscopy is discussed. An example of the spectra processing difficulty negotiation by replacing the Debye relaxation with the overdamped Lorentzian is given.
Study of the local magnetic properties of Fe(Ni,Cu)(SiB) ribbon amorphous alloys produced by ultrafast cooling
Authors: Kaminskaya T. P. , Shipko M. N. , Stepovich M. A. , Tikhonov A. I. , Viryus A. A. , Popov V. V.
Published: April 2024

Magnetic force microscopy was used to investigate the effect of magnetic pulse treatment on the local magnetic properties of the surface of ribbon amorphous Fe(Ni,Cu)(SiB) alloys obtained by ultrafast cooling by melt spraying on a rotating copper drum.
Shear strength of Al–Cu alloy with different types of hardening precipitates: molecular dynamics and continuum modeling
Authors: Bezborodova P. A. , Krasnikov V. S. , Gazizov M. R. , Mayer A. E. , Pogorelko V. V.
Published: April 2024

A molecular dynamics study of the motion of dislocations in aluminum containing hardening copper precipitates is carried out. The paper considers the interaction of dislocation with four types of precipitates, the structure of which was determined in experimental work. The energy of dislocation segments attached to hardening phases is determined and used as a parameter of the continuum model of the dislocation-precipitate interaction. An increase in energy is observed for hybrid precipitates compared to non-hybrid ones.
The non-Wiener dynamics of an ensemble of identical anharmonic oscillators
Authors: Aleksashin M. K. , Basharov A. M. , Trubilko A. I.
Published: April 2024

The model of an ensemble of anharmonic oscillators in the field of a common broadband photon-free thermostat is reduced to a model of an ensemble of identical N-level particles in terms of the algebraic perturbation theory. In one region the model describes the Dicke superadiance, and in the other one—oscillating dependence of the collective radiation intensity on the number of the ensemble oscillator. The collective radiation proves to be suppressed with a certain number of oscillators.
Waveguide structures and photon splitters fabricated by direct (3 + 1)D laser writing
Authors: Kolymagin D. A. , Chubich D. A. , Shcherbakov D. A. , Pattia R. M. , Gritsienko A. V. , Pisarenko A. V. , Dushkin I. V. , Vitukhnovskiy A. G.
Published: April 2024

The problem of high-performance systems for the big data transmission and processing fabrication determines the importance of creating hybrid photonic integrated circuits with complex architecture. We studied of three-dimensional photonic waveguide structures created by direct (3 + 1)D laser writing, with the aim of adding such structures to photonic integrated circuits.
Optical solitons in two coupled waveguides in a planar quadratically nonlinear crystal
Authors: Kalinovich А. А. , Zakharova I. G.
Published: April 2024

The possibility of the formation of spatial-temporal solitons (optical bullets) in coupled quadratically nonlinear gradient waveguides in the range of normal dispersion of the group velocity is investigated. The generation of optical bullets by as well an initial Gaussian beam is demonstrated at both frequencies and only at the fundamental frequency.
Dependence of the temperature sensitivity on the shape of upconversion phosphors NaYF4:Yb,Er
Authors: Zharkov D. K. , Mityushkin E. O. , Leontiev A. V. , Nurtdinova L. A. , Shmelev A. G. , Lyadov N. M. , Pashkevich A. V. , Saiko A. P. , Khasanov O. K. , Nikiforov V. G.
Published: April 2024

Varying the synthesis parameters, NaYF4:Yb,Er phosphors were obtained, which have pronounced upconversion properties upon excitation according to the expression of 980 nm waves. Based on the data of luminescent spectroscopy, it was found that there are 240–350 particles.
The Impact of Stoichiometry and Method of Synthesis of Powder Cu–Fe–Al Precursor on Stability and Activity of Ceramometals CuFeAlO/CuFeAl in High Temperature WGSR
Authors: Tikhov S. F. , Valeev K. R. , Cherepanova S. V. , Salanov A. N. , Saraev A. A. , Kaichev V. V. , Minyukova T. P.
Published: April 2024

Ceramometal catalysts CuFeAlO/CuFeAl, obtained from various powdered Cu–Fe–Al precursors differing in stoichiometry and preparation method, were characterized by physicochemical methods and studied in the water gas shift reaction (CO + H2O ⇌ CO2 + H2). The catalysts are a monolith porous composites, in which metal particles are covered with an oxide shell. The sample Cu : Fe : Al = 45 : 22 : 33, synthesized from powder precursor in two stages was shown to be the most stable. At the first stage the mechanochemical melting of Cu and Fe powders was done. The mechanochemical treatment of obtained product and Al powder was performed at the second stage. This procedure provides the most homogeneous distribution of the components in the precursor. Initial and tested at 400°C ceramometal catalysts were characterized with XRD, SEM and XPS methods. It was revealed that the most active at 350°C catalysts after reductive treatment have Cu1+ and Fe3+ sites. The least active catalysts are completely reduced to Cu0 and partially – to Fe0. It was found that the activity at 330–400°C is determined not only by iron, but also by copper active centers on the surface of the catalysts, or their combined action. Two-stage mechanical activation, apparently, leads to a deeper chemical interaction of the components – Fe and Cu, which provides a higher activity of chromium-free CuFeAl ceramic-metal catalysts.
Phosphate of Zirconium as a Reusable Efficient Catalyst for the Synthesis of 2-Arylquinazolin-4(3H)-ones
Authors: Touayba Ahl el haj  , El Mejdoubi Khalid , Sadraoui Khadija , Idrissi Brahim Chafik EL , Sallek Brahim
Published: April 2024

Our work is around the heterogeneous catalysts based on phosphate. This is all the more important as Morocco has a significant wealth of world reserves of this mineral. This application of natural phosphate alone or modified, has been successfully generalized to many reactions (Claisen Schmidt condensation, selective hydration of nitriles…). And more precisely, the zirconium phosphate catalyst, its physicochemical parameters and catalytic application in the synthesis of 2-arylquinazolin-4(3H)-ones have been studied in order to opt for the one that offers the most economic, ecological and technical advantages.
Machine Learning and Big Data Analysis in the Catalysis Field
Authors: Filippov V. G. , Mikhailov Y. A. , Elyshev A. V.
Published: April 2024

Recently, there has been a rapid development of experimental methods in the field of catalytic research, an increase in the amount of data that is difficult to process and objectively interpret. These methods will allow you to obtain the necessary information from experimental data using statistical approaches such as PCA, MCR, ALS. The use of new statistical and computational data processing methods will accelerate the development and implementation of catalytic technologies. At the same time, machine learning algorithms are beginning to be actively used to interpret and build descriptive models. This article will discuss the main methods of machine learning and their successful application for the analysis of infrared and X-ray absorption spectroscopy data.
Study of Rh/Ce0.75Zr0.25O2 – δ/θ-Al2O3/FeCrAl Catalyst Regeneration after Diesel Fuel Autothermal Reforming
Authors: Shilov V. A. , Rogozhnikov V. N. , Potemkin D. I. , Snytnikov P. V.
Published: April 2024

A study of soot (coke) formation on the surface of a structured Rh/Ce0.75Zr0.25O2/Al2O3/FeCrAl catalyst during autothermal reforming of diesel fuel into synthesis gas was performed. The SEM studies revealed the formation of fibrous carbon particles of 5–50 µm in size on the catalyst surface. It was found that the process of coke formation occurs on the catalytic coating surface, causes no exfoliation and/or damage of the catalytic layer, and the carbon deposits are readily oxidized during catalyst regeneration by oxygen or water vapor. Intensive oxidation of soot with oxygen begins at a temperature of 450°C; a major part of carbon deposits is oxidized even before the reactor furnace reaches the operating temperature of diesel fuel autothermal reforming (750°C). Water vapor oxidizes carbon deposits as well, but less efficiently than oxygen. The catalyst regeneration with water vapor proceeds actively at a temperature of 750°C that proves the possibility of catalyst self-regeneration in the process of diesel fuel autothermal reforming, which is performed with water excess.
Effect of the Hydride and Carbide Phases of Palladium Nanoparticles on the Vibration Frequencies of Adsorbed Surface Molecules
Authors: Usoltsev О. А. , Protsenko B. О. , Pnevskaya А. Yu. , Bulgakov А. N. , Bugaev А. L.
Published: April 2024

Palladium-based materials, including nanoparticles, are widely used in the petrochemical, pharmaceutical, automotive, and other industries. The hydride, carbide, and oxide phases of palladium formed during the hydrogenation or oxidation reactions of hydrocarbons significantly affect the catalytic properties of the catalyst. Based on theoretical calculations performed by the density functional theory (DFT) method, the effect of Pd–Pd interatomic distances and the presence of carbon atoms occupying octahedral voids in the fcc lattice of palladium on the vibrational frequencies of adsorbed hydrocarbons represented by ethylidene is shown. Theoretical research is supported by experimental data of infrared (IR) diffuse reflectance spectroscopy (DRIFTS) collected in situ during the formation of carbide and hydride phases of palladium in commercial Pd/Al2O3 nanocatalysts under the influence of ethylene and hydrogen. The proposed approach can be used to develop new methods for IR spectra analysis leading to the quantitative diagnostics of structural changes in palladium during various catalytic reactions in the in situ mode.
Photocatalytic Degradation of Rhodamine B on MOS2 Microspheres Prepared by Sodium Dialkyldithiophosphate-Assisted Hydrothermal Synthesis
Authors: Ri Yu-Il , Kim Jong-Min , Kim Kyong-Il
Published: April 2024

Abstract—MoS2 microspheres were synthesized via a facile hydrothermal method using (NH4)2MoO4, H2C2O4·2H2O, and sodium dialkyldithiophosphate (NaDDP) as reactants. Herein, NaDDP plays a role of surfactant for the formation of the MoS2 microspheres, unlike other different sulfur sources. The morphology and crystal structure of the MoS2 microspheres were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD). The prepared MoS2 microspheres were used as a catalyst for photocatalytic degradation of rhodamine B. The effect of the size of the MoS2 microspheres on photocatalytic activity was investigated. For comparison, NaDDP was replaced by thiourea, thioacetamide and L-cysteine. The results indicate that the MoS2 microspheres are spherical, and the diameter of the MoS2 microsphere decreases with increasing concentration of oxalic acid in the reactants. The MoS2 microspheres have hexagonal 2H-MoS2 structure and preferentially grow along the (002) plane. In addition, it is found that when the concentration of oxalic acid is 0.075 mol/L, the best photocatalytic efficiency is 91.3% within irradiation time of 120 min and the reaction rate constant is 0.163 min–1. The photocatalytic activity of MoS2 synthesized from four sulfur sources can be arranged in the following order: NaDDP thioacetamide L-cysteine thiourea.
In Situ XRD Investigation of Ni0.9M0.1O (M = Co, Ce, Mn, Zr) Nickel-Based Catalists Activation Process
Authors: Mikhnenko M. D. , Afonasenko T. N. , Rogov V. A. , Bulavchenko O. A.
Published: April 2024

In this work the activation process and the effect of modifying additives on the phase composition and structure of a series of catalysts with the general composition Ni0.9M0.1O (M = Co, Ce, Mn, Zr) synthesized by co-precipitation were studied. The influence of the additives on the initial state of the samples was investigated by XRD, and their influence on the NiO reduction process was studied by in situ XRD and TPR-H2. It was shown that the introduced modifiers influence on the structure and microstructure of the initial samples, increasing the value of the specific surface and decreasing the average size of NiO CSR. Introduction of Mn, Co leads to formation with NiO oxide of solid solutions of replacement. For Ce and Zr the release of CeO2 oxide and X-Ray-amorphous ZrOx is observed. The use of these additives leads to an increase in the temperature of NiO reduction to the metallic state compared to the massive oxide. In addition, the effect of modifying additives on the particle size of the final metal is observed. The introduction of Ce and Mn decreases the average size of the NiO CSR in 2–5 times compared to the massive NiO.
Carbon Catalyst Support Modification by Nitrogen Via Nitric Oxide Treatment
Authors: Semikolenov S. V. , Dmitrachkov A. М. , Kvon R. I. , Bukhtiyarov V. I. , Nartova А. V. , Ananina A. A.
Published: April 2024

In the present work the method of carbon material Sibunit modification by the NO treatment under static reactor condition is proposed. It is shown that the composition and amount of nitrogen- and oxygen-contained functional groups is determined by the treatment conditions (temperature, duration), which allows controlling the result of the modification. The process of Sibunit modification by NO is studied by XPS and N2 adsorption. The mechanism of Sibunit modification as the carbon layers etching by NO through the conversion of oxygen-contained functional groups into NOx-groups (–NO and –NO2) and further into pyridic and pyrrolic nitrogen-contained groups is assumed. Developed procedure of nitrogen introduction into carbon material is simple for realization, that is important for practical applications.
Kinetics and Mechanism of the CO Oxidation to CO2 in the PdBr2–CuBr2–THF–H2O Catalytic System
Authors: Putin А. Yu. , Katsman E. A. , Bruk L. G.
Published: April 2024

The kinetics of the CO oxidation to CO2 in the PdBr2–CuBr2–THF–H2O system was studied outside the coupled process of cyclohexene hydrocarboxylation. The kinetic model was obtained and the reaction mechanism was proposed. The influence of the hydrocarboxylation reaction of alkenes on the CO oxidation to CO2 was established in the coupled process which has been previously studied.
Effect of Nickel Promoted Niobium Catalyst on Toluene Nitration Reaction
Authors: Sahebi M. , Nasiri M. , Shokrollahi A.
Published: April 2024

A series of Ni–Nb2O5/SiO2 catalysts with varying Ni loadings (5–25 wt. %) were prepared. The catalytic activity of the materials was evaluated by nitration of toluene. Ni–Nb2O5/SiO2 catalyst showed good catalytic activity, selectivity, and reusability for the nitration of toluene. Under the optimal conditions, conversion of toluene by 88% to mononitrotoluene was achieved with 100% selectivity. Experiments were designed by the Minitab software, and the effect of reaction conditions was investigated. The optimal reaction condition was also achieved for the high amount of total products and the lowest amount of meta-isomer using this software. The reusability of catalyst also was studied in this work at the same operating conditions, and the catalyst was stable for four runs without losing catalytic activity.
Mechanism of the Hydrazine Monohydrate Decomposition by Means of IR Spectroscopy In Situ
Authors: Matyshak V. A. , Silchenkova O. N. , Ilichev A. N. , Bykhovsky M. Ya. , Mnatsakanyan R. А.
Published: April 2024

Pd-containing catalysts (1%Pd/Al2O3 and 5%Pd/Al2O3) deposited on aluminum oxide were studied in the decomposition reaction of hydrazine monohydrate. According to in situ IR spectroscopy, it was found that hydrazine monohydrate is adsorbed on the coordination unsaturated centers of the catalyst surface in a linear form. When the temperature rises, the adsorbed hydrazine monohydrate loses a water molecule, which is accompanied by a change in the geometry of the molecular complex. Adsorption of hydrazine on a support and its diffusion onto palladium clusters is a more advantageous process than direct adsorption on active centers. This circumstance shows that the hydrazine adsorbed on the support can be an intermediate of its decomposition process. The studied catalysts have a maximum activity in the temperature range of 100–120°C, while the ratio of hydrogen and nitrogen concentrations in the reaction products was equal to 2, which corresponds to 100% selectivity for hydrogen. As the reaction temperature increases, the selectivity decreases significantly. The explanation of the high selectivity for hydrogen at low temperatures is due to the fact that the adsorption of N2H4 is carried out through the formation of hydrogen–metal bonds. The hydrogen–metal bond strength in such a complex is higher than the nitrogen–metal bond strength, hence the barrier for breaking the N–H bond is lower than the barrier for breaking N–N bond, which leads to breaking N–H bond and preserving the N–N bond. At elevated temperatures, some of the hydrogen atoms formed recombine, the other reacts with the surface complexes of hydrazine to form the intermediate NH3–NH3, the breaking of the bond in which leads to the formation of ammonia molecules in the gas phase.
Prospects of Using Ruthenium within the Composition of Three-Way Palladium–Rhodium Catalysts
Authors: Shubin Y. V. , Plyusnin P. E. , Kenzhin R. M. , Vedyagin A. A.
Published: April 2024

The possibility of using ruthenium within the composition of palladium-rhodium catalysts used to neutralize the exhaust gases of vehicles with gasoline engines was investigated. Thermolysis of the supported precursor in oxidizing and reducing media leads to the formation of samples with different initial catalytic activity. Stability of trimetallic systems is compared under conditions of prompt thermal aging with reference samples of similar chemical composition, but obtained by mechanical mixing of monometallic catalysts. The obtained results allow one to conclude that the alloy nanoparticles are more stable, and the thermolysis of the precursor in the reducing medium contributes to a higher initial activity of the catalyst in the oxidation of CO. According to the X-ray photoelectron spectroscopy method, the high thermal stability of trimetallic catalysts is due to the constant ratio of metals on the surface of the support during the catalytic reaction.
Kinetics of the Reaction of Oxyethylation of Alcohols in Considering the Influence of Association. Kinetic Aspects of Association
Authors: Stul’ B. Ya.
Published: April 2024

It is assumed that in the reaction of alcohol oxyethylation, the kinetically independent unit is not a monomeric alcohol molecule, but a linear chain alcohol associate, consisting, on average, of n alcohol molecules. Тhe reaction rate is of the first order not by the gross concentration of alcohol, but by the concentration of these associates. It has been suggested that first-order reactions with respect to the associated component, which are widespread in liquid-phase chemical kinetics, take place as a result of the release of the reaction product from the associate.
Numerical Simulation of Turbulent Flow Control
Authors: Lushchik V. G. , Makarova M. S. , Reshmin A. I.
Published: April 2024

Various methods of flow relaminarization in a pipe are considered by means of controlling the average and turbulent flow parameters. For numerical simulation of flows with turbulence growth and suppression it is proposed to use a three-parameter RANS turbulence model, which has shown good results in modeling existing experiments on relaminarization. Calculations for three variants of inlet devices with different velocity profiles and the same small-scale turbulence at the inlet show the possibility of achieving flow relaminarization in pipes at Reynolds numbers Re 10000. Among three variants of inlet devices considered, the most effective one is the variant with organization of a twozone flow with slow flow in the central region of the pipe and accelerated flow in the near-wall region. In this version, relaminarization occurs up to the Reynolds number Re* = 16000. It is shown that decrease in the turbulence intensity and scale leads to an even larger value of the relaminarization Reynolds number Re*.
NON-EQUILIBRIUM SUPERSONIC FLOW AROUND A BLUNT
Authors: Surzhikov S. T.
Published: April 2024

The computational model designed for studying the processes of non-equilibrium physicochemical gas dynamics in supersonic rarefied-air flow past a blunt plate of finite dimensions under the laboratory experiment conditions is formulated. The computational model is based on the two-dimensional Navier–Stokes equations, the energy conservation laws for the translational degrees of freedom of atoms and molecules and the vibrational degrees of freedom of diatomic molecules, and the chemical kinetics and diffusion equations for individual components of partially ionized gas flow. The basic gas dynamic and kinetic processes in flow past a blunt plate are analyzed at the Mach numbers M = 10 and 20. It is shown that regions of thermal nonequilibrium are formed.
Mathematical Modeling of the Effect of Cell Mobility and Active Intercellular Interactions on the Sorting of the Cells of Two Types in the Cultures of Biological Tissues
Authors: Logvenkov S. A.
Published: April 2024

The cell motion is at the bottom of many biological phenomena. An important role in controlling cell motions is played by active stresses developing in biological tissues as a result of mechanical intercellular interactions. An investigation of the evolution of the mixtures of cells of different types forming cell aggregates shows that active intercellular force interactions lead to the spatial separation of the cells of different types, or the cell sorting. Within the framework of the continuum model of biological media [24] (the cells of different types are regarded as separate phases), in this study we investigate the effect of the parameters characterizing various mechanisms of the development ofactive intercellular stresses, as well as adhesion and cell mobility, on the process of the sorting of cells of two types that form an aggregate of spherical shape at the initial moment of time. It is shown that the sufficient condition for the sorting of cells of different types and the formation of a sharp boundary between the regions occupied by these cells is the absence of contracting interactions between the cells of different phases under the condition of asymmetry of the initial distributions of their concentrations or asymmetry of the parameters characterizing the development of active stresses in different phases. It is shown that the cells of the phase, where active contracting intercellular interactions are stronger (at the same values of the other parameters and the same initial distributions of phase concentrations for different cell phases), strive to occupy the central region of a spheroid. At the same time, the cells of the other phase, where the contracting interactions are weaker, are displaced to the periphery. An increase in the parameter characterizing cell repulsion leads to the displacement of this cell phase toward the periphery. Beside the active interaction forces, the cell motions can be controlled by both passive mechanical properties of the medium and the cell mobility. The asymmetry of the interphase distributions of these parameters can lead to the situation, when the cells that possess the greater contracting interactions will be displaced toward the cell spheroid periphery and surround the cells, the interaction between which is weaker
Experimental Study of Energy Separation in Compressible Air Cross Flow Over a Pair of Side-by-Side Circular Cylinders
Authors: Vinogradov Yu. A. , Zditovets A. G. , Kiselev N. A. , Popovich S. S.
Published: April 2024

The influence of the distance between two circular side-by-side cylinders in a cross flow on the surface distribution of temperature and static pressure is experimentally studied. The studies were carried out at free-stream Mach numbers M equal to 0.295 and 0.365 and Reynolds numbers ReD equal to 6.4 × 104 and 7.9 × 104, respectively. The surface distributions of the pressure coefficient and the temperature recovery factor for one of the cylinders are obtained. It is shown that, depending on the distance between the cylinders, the pressure coefficient and temperature recovery factor can be both higher and lower than the values obtained in the flow over a single cylinder with the same free-stream parameters.
Motion of a Load on an Ice Cover in the Presence of a Current with Velocity Shear
Authors: Tkacheva L. A.
Published: April 2024

The behavior of an ice cover on the surface of an ideal incompressible fluid of finite depth under the action of a pressure domain that moves rectilinearly at a constant velocity in the presence of a current with velocity shift is studied. Fluid flow is not potential. The ice cover is modeled by a thin elastic plate with account for uniform compression. The motion of the load can occur at an arbitrary angle to the direction of current. It is assumed that the ice deflection is steady in the coordinate system moving with the load. The Fourier transform method is used within the framework of the linear wave theory. The critical velocities and the deflection of ice cover are studied depending on the current velocity gradient, the direction of motion, and the compression ratio.
Determination of Yield Strength of Single-Crystals with a Hexagonal Lattice at a Given Strain Tensor and Hydrostatic Pressure
Authors: Kesare A. G. , Vlasova A. M.
Published: April 2024

Within the framework of the Mises yield criterion generalized to hexagonal crystals proposed by the authors, the problem of determining the stress tensor depending on the strain rate tensor and the applied external pressure is solved. The cases of plane and uniaxial deformation are considered in detail for an arbitrary orientation of the crystal lattice. For the cases of plane and uniaxial deformation, diagrams of stress level lines for the onset of plastic flow are plotted. Diagrams are given for the components of the stress tensor deviator
To the Static Stability of the Cross-Sectional Shape of a Pipeline, Cylindrical Shell, Carbon Nanotube
Authors: Khakimov A. G.
Published: April 2024

Based on the assumption about the initial deformed shape of the cross section of the pipeline, cylindrical shell, carbon nanotube (CNT) without initial stresses, the critical pressures inside and outside these structural elements are determined. The static interaction of instabilities under the action of the above factors is studied.
Results of Experimental and Theoretical Studies of the Possibilities of the Resonance Method of Ice Cover Destruction
Authors: Kozin V. M.
Published: April 2024

Based on experiments carried out: in ice basins; with large-scale models of hovercraft in the field; with full-scale hovercraft, as well as using theoretical dependencies for calculating the stressstrain state of the ice cover from the action of moving loads, the possibilities (patterns) of the resonant method of ice destruction, i.e., by excitation of resonant flexural-gravity waves (FGW), were studied. Its physical essence, the expediency of its implementation by a hovercraft are explained, the possible areas of effective use of this method are indicated. The results of the information review on the topic of the work are given, on the basis of which the purpose of the research is set. When describing the viscoelastic nature of the relationship between stresses and strains in ice, the Kelvin-Voigt law of deformation of an elastically retarded medium was used. The theoretical bending potential energy density of an infinite plate was taken as a criterion for the ice breaking capacity of FGW. In this case, the condition is used that when it reaches a certain value, complete (with the opening of cracks) destruction of ice occurs. The initial data for these calculations are taken from the performed experiments. Dependences are given that make it possible to determine the parameters of a load moving at a resonant speed (hovercraft parameters) sufficient to destroy an ice cover of a given thickness under given ice conditions.
Control of the Dynamic Parameters of a Flat Beam Structure by Selection of Fixing
Authors: Kudryavtsev I. V. , Ivanov V. A. , Sukhodoeva N. V. , Rabetskaya O. I. , Mityaev A. E.
Published: April 2024

This article proposes a method for the justified choice of the fixing method, the type of supports and their stiffness for flat beam structures of an axisymmetric cross section in order to ensure the specified values of the first frequency of natural bending vibrations and the first critical load, by taking into account the action of longitudinal forces and temperature changes. The technique is based on the well-known provisions of the theory of beam oscillations, the Euler’s theory of stability, and uses the coefficients of supports as a criterion for choosing a fixing method, which are pre-normalized to achieve comparable values. The selected fixing provides the specified value of the first natural oscillation frequency, the value of the first critical temperature, or simultaneously both conditions of working efficiency. According to the developed method, comparative calculations of a flat bar structure using the finite element method have been performed. They has shown good convergence of the results for all controlled parameters. The proposed approach can be used in the design of support fixing of flat beam structures for various purposes to ensure their dynamic behavior.
Experimental Investigation of the Properties of Auxetic and Non-Auxetic Metamaterials Made of Metal During Penetration of Rigid Strikers
Authors: Ivanova S. Yu. , Osipenko K. Yu. , Kuznetsov V. A. , Solovyov N. G. , Banichuk N. V. , Lisovenko D. S.
Published: April 2024

The properties of metal honeycomb metamaterials with different internal structures were experimentally studied when they were punched along the normal by a rigid spherical striker. Experiments with metal samples of metamaterials with a negative Poisson’s ratio (auxetics) showed a greater resistance to penetration by impactors than experiments with metal samples having a honeycomb structure with a positive Poisson’s ratio.
Calculation of Life Characteristics for Structural Alloys under the Mutual Influence of Fatigue and Long-Term Strength
Authors: Volkov I. A. , Igumnov L. A. , Volkov A. I. , Yudintseva A. I.
Published: April 2024

The processes of degradation of the initial strength properties of polycrystalline structural alloys are considered under mechanisms that combine low-cycle fatigue and long-term strength of the material. From the point of view of mechanics of damaged medium (MDM) and fracture mechanics (FM), a mathematical model that describes the processes of cyclic viscoplastic deformation and damage accumulation in structural alloys under multiaxial disproportionate modes of combined thermomechanical loading has been developed. The model consists of three interrelated components: relations that determine the cyclic viscoplastic behavior of the material by taking into account the dependence on the fracture process; evolutionary equations describing the kinetics of damage accumulation; criterion of the strength of the damaged material. The viscoplasticity model is based on the idea of the existence of plasticity and creep surfaces in stress space and the principle of gradient vectors of plastic and creep strain rates to the corresponding surface at the loading point. This form of the equations of state reflects the main effects of cyclic viscoplastic deformation of the material for arbitrary complex loading trajectories. The form of kinetic equations for damage accumulation is based on the introduction of a scalar damage parameter and on energy principles. It also takes into account the main effects of the formation, growth and merging of microdefects under arbitrary complex modes of combined thermomechanical loading. A joint form of the evolutionary equation for damage accumulation in the areas of low-cycle fatigue and long-term strength of the material is proposed. As a criterion for the strength of a damaged material, the condition for reaching a critical value is used. The material parameters and scalar functions included in the constitutive relations of the MDM mathematical model are obtained. The results of numerical simulation of the processes of deformation and damage accumulation in structural alloys under the mutual influence of low-cycle fatigue and long-term strength of the material are presented. The results of comparison of calculated and experimental data show that the proposed MDM model qualitatively and with the accuracy necessary for practical calculations quantitatively describes the durability of materials under the mutual influence of low-cycle fatigue and long-term strength of the material.
The Influence of Average Pressure on the Eigenfrequencies of Oscillations of a Carbon Nanotube
Authors: Khakimov A. G.
Published: April 2024

The bending oscillation frequencies of a carbon nanotube (CNT) are determined using the semi-momentless theory. An expression for the distributed lateral load on CNT is derived under the assumption of its cylindrical bending. CNT surfaces come into contact with media of varying densities and pressures. The medium can be compressible during surface deformation and incompressible. The influence of average pressure and changes in the curvature of the middle surface, as well as the added mass of the gaseous medium, on the bending is determined.
One Approach to the Plane Problem on Impact of Timoshenko-Type Shells on Elastic Half-Space
Authors: Bogdanov V. R.
Published: April 2024

The article presents an attempt to solve the plane problem on the impact of an elastic Timoshenko shell on an elastic half-space using the method of reducing problems of dynamics to the solution of a Volterra's infinite system of integral equations (ISIE) of the second kind. It is shown that such an approach is not acceptable. When discretizing the reduced Volterra's ISIE of the second kind, a poorly defined system of linear algebraic equations is obtained: as the reduction order increases, the determinant of such a system tends to infinity. This circumstance shows the limitations of this approach.