bluuebunny/crossref_metadata_2025 huggingface dataset:
Absorbing Screens of Microstrip Assemblies
Authors: Alimov M. V. , Zhukov A. A. , Yakukhin S. D.
Published: April 2024

A screen that absorbs electromagnetic radiation has been proposed, a micromachine technology for its production has been developed based on volumetric microprocessing of single-crystalline silicon,experimental samples have been manufactured, and their characteristics have been studied. It is shown that in the measurement frequency range of 14.7–26.7 GHz there is a smooth increase in the attenuation introduced by the absorbing screen with increasing frequency to a maximum value of 20–23 dB at a frequency of about 20 GHz, and then a smooth decline. The amount of attenuation increases as the length of the screen increases and can reach any value. The manufactured samples of the absorbing screen provide significant attenuation in the required frequency range with a small substrate thickness and can be successfully used in space equipment to ensure electromagnetic compatibility.
On the Theory of Capacitive Discharge in a Transverse External Magnetic Field
Authors: Kartashov I. N. , Kuzelev M. V.
Published: April 2024

The electrodynamic properties of the plasma of a high-frequency capacitive discharge with a magnetic field along the capacitor plates are considered. The complex impedance of such a system is calculated. Based on the equivalent electrical circuit of a plasma capacitor, the resonant properties of the discharge are analyzed. The role of ions in the stability of an electron flow drifting in crossed electric and magnetic fields has been demonstrated.
Obtaining Textured Nickel Antimonide Films
Authors: Luzanov V. A.
Published: April 2024

It was shown for the first time that when nickel is deposited onto a heated gallium antimonide substrate, diffusion of antimony atoms from the substrate into the growing film occurs and a nickel antimonide film is formed, which has an axial texture with an axis perpendicular to the film plane along the (101) direction.
On the Features of Calculating Linear Parameters and Characteristics of Multi-Wire Transmission Lines
Authors: Maksimov A. E. , Kuksenko S. P.
Published: April 2024

The features of calculating the matrices of linear parameters and characteristics of multi-wire transmission lines have been considered. The method of calculation of the matrices of primary linear parameters of multi-wire transmission lines has been presented. The criteria for the accuracy of the calculation of the capacitive matrix have been formulated. It has been noted that it is necessary to accurately account for the mutual influence between the transmission line conductors for a correct estimation of the distortions of thesignals propagated in it. The influence of the linear parameters of multi-wire transmission lines on responses and eye diagrams at the end of their active conductors has been demonstrated. The influence of the distances from the extreme conductors to the boundaries of the cross-sections of transmission lines on the accuracy ofcalculating their capacitive matrices has been studied. Using the method of moments, it has been shown that known approaches to determining these distances do not always give accurate or efficient results. On the example of several transmission lines with different numbers of dielectric layers and conductors, as well as with the screen and without it, the minimum values of this distance at which it is possible to achieve an accurate and efficient calculation of their capacitive matrices have been determined.
Dependence of Reversible and Irreversible Failures of Semiconductor Devices on the Repetition Rate of Powerful Pulse Electromagnetic Interference
Authors: Usychenko V. G. , Sorokin L. N. , Sasunkevich A. A.
Published: April 2024

The mechanisms of reversible and irreversible failures that occur in microwave semiconductor devices, microcircuits, and microprocessors under the action of powerful electromagnetic pulses, either single or periodic, are analyzed. It is shown that, in microprocessors, failures of both types are generated by theelectrothermal instabilities, which develop in negligibly small volumes of a device. The dependences of the threshold energy of failures on the pulse amplitude, length, and repetition rate are explained. The results of the calculation are consistent with the experimental data.
The Genus Iris (Iridaceae) in Russia: Phytochemistry, Biological Activity and Application in Traditional Medicine
Authors: Alexeeva N. B. , Dorofeeva M. M. , Varfolomeeva E. A. , Mironova L. N.
Published: April 2024

The genus Iris in Russia is represented by 41 species, of which 4 species are endemic, 11 are included in the Red Book of the Russian Federation and 30 have various regional conservation status. The review provides information on the phytochemical compounds, biological activity and medicinal properties of 16 species growing in Russia, and on their use in traditional medicine of different peoples. The analysis of available data shows that studying the component composition, biological activity levels, and medicinal use of Iris L. species requires their correct identification and the knowledge concerning their geographical distribution, ecology, and morphological characteristics. The use of Iris species in traditional medicine is described. The extracts and compounds isolated from the most of the studied species exhibit analgesic, antioxidative, antipyretic, anti-inflammatory, antibacterial and antimicrobial activity. Some species also have cytotoxic, antitumor, antidiabetic, anti-influenza, neuroprotective, antihyperglycemic, antiallergic, antifeedant and other properties. Most of the isolated metabolites were flavonoids, isoflavonoids, anthocyanes, terpenoids, xantgones, quinones, phenolic and fatty acids. In official and traditional medicine in Asia and Europe, the underground and aboveground parts of Iris aphylla, I. lactea, I. pseudacorus, I. ruthenica, I. sanguinea and other species of the genus are used. The article results from the long-term studies of irises in situ and in the collections of two botanical gardens, as well as extensive examination of literature on the component composition and medicinal properties of the studied species.
Assessment of Total Mineral Content in Raw Materials of Ten Medicinal Plants from Roadside Biotopes (Voronezh Region)
Authors: Dyakova N. A.
Published: April 2024

Abstract—The total mineral content in medicinal plants from the roadside and railside coenoses of the Voronezh region was studied. The pharmacopoeial plant raw materials of 10 species were evaluated: roots of Taraxacum officinale F.H. Wigg and Arctium lappa L.; herb of Polygonum aviculare L., Artemisia absinthium L., Leonurus quinquelobatus Gilib., and Achillea millefolium L.; leaves of Urtica dioica L. and Plantago major L.; flowers of Tanacetum vulgare L. and Tilia cordata Mill. For collecting medicinal plant raw materials, the minimum allowable distances from different types of roads and railways were determined based on the total ash content indicator. For different natural zones, the minimum allowable distance from the heavy traffic motorways is: forest zone – 210 m, forest–steppe zone – 240 m, and steppe zone (devoid of tree and shrub vegetation) – 380 m. For secondary low-speed roads and railways, the minimum recommended distance is 80 m.
Plant, Lichen and Fungi Forage Species of Reindeer Pastures in the Olyutorsky District of the Koryak Region (Kamchatka Territory)
Authors: Neshataeva V. Yu. , Skvortsov K. I. , Yakubov V. V.
Published: April 2024

Abstract—A list of forage plants, lichens and fungi of reindeer pastures of the Olyutorsky District of the Koryak Region was compiled for the first time. 233 species of vascular plants from 37 families, 37 species of forage lichens and 7 genera of mushrooms were identified. The main species of fodder lichens in the Korjak District are: Cladonia stellaris (Opiz) Pouzar et Vězda, C. rangiferina (L.) F.H. Wigg., C. arbuscula (Wallr.) Flot. s.l., C. mitis Sandst., Flavocetraria cucullata (Bellardi) Kärnefelt et Thell at all. The main forage plants are: Salix pulchra Cham., S. alaxensis Cov., S. krylovii E. Wolf, S. saxatilis Turcz. ex Ledeb., S. arctica Pall. et all; Betula exilis Sukacz., B. middendorffii Trautv. et Mey.; Arctophila fulva (Trin.) Anderss., Calamagrostis purpurea (Trin.) Trin. s.l., Poa L. spp., Festuca L. spp.; Carex lugens H. T. Holm., C. globularis L., C. appendiculata (Trautv. et C.A. Mey.) Kük., C. lyngbyei Hornem. subsp. Cryptocarpa (C.A. Mey.) Hultén, C. rhynchophysa C.A. Mey.; Eriophorum vaginatum L., E. polystachyon L., E. russeolum Fries, E. scheuchzeri Hoppe; E-quisetum L. spp.; Fabaceae, Asteraceae, Polygonaceae species. For each species, the family, life-form (biomorph), edible plant organs and grazing seasons were indicated. Regional patterns of the reindeer pastures vegetation in the North of the Koryak Region are discussed; some grazing preferences of Chukchi deer breed are noted.
Comparative Analysis of the Component Composition of Flowers in Some Species of the Genus Syringa (Oleaceae)
Authors: Pupykina K. A. , Polyakova N. V. , Kudashkina N. V. , Krasyuk E. V.
Published: April 2024

Abstract—Due to the insufficient knowledge of the lilac flowers component composition, a comparative analysis of 6 species of the genus Syringa L. from the collection of the South Ural Botanical Garden-Institute of the Ufa Federal Research Center RAS was carried out. S. emodi Wall., S. josikaea Jacg., S. komarowii Schneid., S. reticulata (Blume) H. Hara ssp. amurensis (Rupr.) P.S. Green et M.C. Chang, S. sweginzowii Koehne et Lingelsh, S. vulgaris L. were studied. The content of the major groups of biologically active compounds, namely flavonoids, hydroxycinnamic acids, tannins and organic acids, was established. The highest content of all identified groups of biologically active substances (BAS) was found in flowers of S. komarowii: flavonoids ‒ 4.25 ± 0.21%, hydroxycinnamic acids ‒ 6.13 ± 0.29%, tannins – 9.3 ± 0.5%, ascorbic acid ‒ 0.468 ± 0.022%, and organic acids ‒ 10.7 ± 0.5%. In S. emodi and S. sweginzowii the content of these BAS is little less than in S. komarowii, and the minimum amount of BAS was found in S. josikaea. A comparative analysis of the qualitative and quantitative profiles of the BAS major groups in some lilac species cultivated in the Republic of Bashkortostan shows the prospects for their further study with the objective of their possible use in scientific medicine, and for the development of herbal remedies.
State of Limonium gmelinii (Plumbaginaceae) Coenopopulations in the Republic of Khakassia
Authors: Barsukova I. N. , Cheryomushkina V. A.
Published: April 2024

Abstract—The study is focused on the characteristic halophyte of Khakassia – Limonium gmelinii (Willd.) Kuntze (Plumbaginaceae). There is no information on the structure and assessment of the state of the coenopopulations of L. gmelinii in Khakassia. The materials were collected in 2022 from steppe and meadow plant communities with varying degrees of salinity. It was found that L. gmelinii coenopopulations are stable. The studied coenopopulations are normal, complete and incomplete. The left-sided type of the ontogenetic spectrum is formed in the alkaline steppe with low total projective cover and sufficient moisture; centered – on slightly saline or almost non-saline substrate of grass-covered steppe and meadow communities under different moisture regimes. The change in the ontogenetic structure and an increase in the undergrowth are associated with seed renewal and ecological and phytocenotic conditions of habitats. The density of individuals depends on the ecological and phytocenotic environment. The maximum total score of organismal and populational characters in Limonium gmelinii individuals was observed on slightly saline and practically non-saline soils in the cold sagebrush-grass and sagebrush real steppes of Khakassia. On the steppe meadows with low salinity, extensive grass cover and lack of moisture, the species does not reach the optimum. On highly saline soils, under low competition from related species and sufficient moisture, the total score of organismal and population characters reaches an average value.
Adsorption of Organic Compounds on the Surfaces of Silicas with Grafted Acetoacet Ether Groups Saturated with Transition Metal Ions
Authors: Pakhnutova E. A. , Slizhov Yu. G.
Published: April 2024

A set of physicochemical means is used to study the adsorption properties of surfaces of silicas based on Silochrome C-120 with surface-grafted groups of acetoacetic ester saturated with transition metal ions. Gas chromatography is used to study the effect nickel, cobalt, and copper ethylacetoacetates have on the thermodynamic characteristics of adsorption (TCA) of different classes of organic substances on SiO2. Experimental data on the retention of adsorbates with different donor-acceptor properties (n-alkanes and chloroalkanes, alkenes, aromatic and oxygen-containing substances) are used to calculate differential molar heats of adsorption q¯dif,1 the change in the standard differential molar entropy ΔS¯S1,C and deposits Δq¯dif,1(spec) in the energy of dispersion and specific interactions.
Effect of a Geometric Potential on the Eigenfunction and Eigenvalue of the Energy of State in a Twisted Graphene Nanoribbon
Authors: Sadykov N. R. , Petrova Yu. A. , Pilipenko I. A. , Khrabrov R. S. , Skryabin S. N.
Published: April 2024

An expression is obtained for an effective geometric potential based on a coordinate system for a nanoribbon twisted in the form of a helicoid. The effective geometric potential for a Schrödinger equation is used to study a graphene nanoribbon of finite length with “armchair” edges under the action of an external electric field parallel to them. Solutions are calculated for the energy levels and wave functions of electrons in the vicinity of the Dirac point. It is shown there is only one state in the transverse direction.
Thermodynamic Properties of Sm3Cl7 Chloride in the Standard State at 298.15 K
Authors: Goryushkin V. F. , Bendre Yu. V. , Lezhava S. A.
Published: April 2024

The EMF in the 473–728 K range of temperatures is measured for solid-phase galvanic cells (‒) Sm|SmCl2||BaCl2||SmCl3|Sm3Cl7 (+), (–) Sm|SmCl2||BaCl2||Sm3Cl7|SmCl2 (+), (–) SmCl2|Sm3Cl7|| BaCl2||SmCl3|Sm3Cl7 (+), and (–) Mg|MgCl2||BaCl2||SmCl3|Sm3Cl7 (+). Experimental data are processed according to the second law of thermodynamics using literature values of thermodynamic characteristics of the components of the EMF-forming reaction: Sm, Mg, SmCl2, SmCl3, and MgCl2. Values of the standard Gibbs energy of formation, the standard enthalpy of formation, and the standard entropy of chloride Sm3Cl7 at a temperature of 298.15 K are obtained by averaging data on four galvanic cells.
Obtaining Methanol from CO2 on Cu–Zn/Al2O3 and Cu–Zn/SiO2 Catalysts: Effect of the Support and Conditions of the Reaction
Authors: Kim K. O. , Shesterkina A. A. , Tedeeva M. A. , Kartavova K. E. , Pribytkov P. V. , Dunaev S. F. , Kustov A. L.
Published: April 2024

A study is performed of the catalytic properties of Cu–Zn catalysts on Al2O3 and SiO2 supports (Acros) in the reaction of CO2 hydrogenation to obtain methanol. A sample of 30Cu15Zn/Al2O3 displays great selectivity toward methanol. A sample of 30Cu15Zn/SiO2 has the highest methanol performance. The methanol performance of a sample of 10Cu5Zn/Al2O3 is doubled when the pressure is raised from 10 to 30 atm, and a 94% increase in selectivity is observed. A sample of catalyst 10Cu5Zn/SiO2 does not lose its activity after 10 h of a catalytic reaction, and its methanol performance grows with repeated use
Study of the Рossibility of Using Waste from the Agro-Industrial Complex and the Woodworking Industry in Order to Obtain High-Energy Fuel and Carbon Adsorbents
Authors: Krasnikova E. M. , Moiseenko N. V. , Goncharov V. V.
Published: April 2024

Growing concerns about the environment are prompting the search for alternative energy sources and the possibility of processing agricultural waste into highly efficient absorbents. That is why the article considers methods for obtaining high-energy fuel from pinewood using acidic additives and the possibility of using chemically treated cherry stone shells as a carbon sorbent is evaluated. With the use of low-temperature pyrolysis, a number of carbon-containing materials have been obtained. The carbon content in these materials depends on the reagent used to treat the feedstock, the temperature and time of pyrolysis. The subsequent activation of carbonizate from the cherry stone shell with oxidizing agents revealed that nitric acid significantly increases the cation-exchange capacity of the material, which allows it to be used as an adsorbent.
An Equation of State of Corundum Based on Planck–Einstein Functions
Authors: Perevoshchikov A. V. , Kovalenko N. A. , Uspenskaya I. A.
Published: April 2024

The possibility of constructing the equation of state of a crystalline substance based on a linear combination of the Planck–Einstein functions is shown using the example of corundum α-Al2O3. Two versions of the corundum equation of state are obtained on the basis of functions F(V,T) and G(P,T) as a result of the self-consistency of the heat capacity values, the enthalpy increment, PVT data, the coefficient of thermal expansion, and the adiabatic modulus of elasticity. Both equations provide an acceptable description of the above properties in a wide range of variables (up to a pressure of 165 GPa and a temperature of 2250 K).
Inhibition of the Formation of Pyrophoric Corrosion Deposits
Authors: Reformatskaya I. I. , Begishev I. R. , Ascheulova I. I. , Podobayev A. N. , Petrilin D. A. , Baburin A. V.
Published: April 2024

Laboratory studies and field tests identify the presence of a pyrophoric compound (iron disulfide) in the corrosion products of the internal surfaces of the walls as the main cause of spontaneous combustion of the tanks with sulfurous oil. When nitrogen is introduced into the vapor-gas phase, the formation of pyrophore in the tank stops and the probability of spontaneous combustion significantly reduce. This strongly reduces the corrosion rate as well.
Temperature Effect on the Acid–Base Properties of β-Alanine in Aqueous Solution
Authors: Samadov A. S. , Khakimov J. N. , Stepnova A. F. , Faizullozoda E. F. , Kuzin A. V.
Published: April 2024

The acid–base properties of β-alanine (β-Ala) in aqueous solution were studied by the pH-metric method in the temperature range 278.2–318.2 K and at I = 0.1 M KCl. The ionization constants (pKi) of β‑Ala at different temperatures were calculated. The ionization constants were found to change depending on the temperature: an increase in the temperature leads to a decrease in pKi for both carboxyl and amine groups, which indicates that the degree of ionization of β-alanine increased and its acidic properties were enhanced. The thermodynamic characteristics (ΔН0, ΔS0, and ΔG) of the corresponding ionization processes were determined by the temperature coefficient method.
New Barium Fluorosuccinato and Fluoroglutarato Uranylates
Authors: Serezhkin V. N. , Grigoriev M. S. , Sukacheva M. V. , Serezhkina L. B.
Published: April 2024

Two new coordination polymers: Ba2[(UO2)3(suc)3F4]⋅5H2O (I) and Ba[(UO2)2(glt)2(Hglt)F]⋅8H2O (II), where suc is C4H4O2−442− (succinate ion) and glt is C5H6O2−442− (glutarate ion), were synthesized, and their structure was studied. The uranium-containing structural units of crystals I are the [(UO2)3(C4H4O4)3F4]4– layers belonging to the crystal-chemical group A3(Q02)3M22M22M12M21 of uranyl complexes, where A = UO2+2UO22+, Q02 = C4H4O2−442−, М1 and М2 = F–. Structure II contains the uranium-containing 3D complex [(UO2)2(C5H6O4)2(C5H7O4)F]2–, which corresponds to the crystal-chemical formula A2(Q02)2B01M2, where A = UO2+2UO22+, Q02 = C5H6O2−442−, B01 = C5H7O−44−, and М2 = F–.
Sonoluminescence of Aqueous Solutions of CaCl2 and NaCl: The Effect of Concentration
Authors: Gordeychuk T. V. , Kazachek M. V,
Published: April 2024

The structure of the sonoluminescence spectra of argon-saturated aqueous solutions of CaCl2 and NaCl of various concentrations is considered in detail. The frequency of ultrasound is 20 kHz, and the output power is 18 W. The spectrum of the CaCl2 solution changes considerably as the concentration rises. The intensity of the continuum passes through a maximum near the saturation concentration. Atomic, ionic, and molecular metal lines are observed for medium concentration values and disappear at high concentrations. Similar behavior is displayed by the spectra of NaCl solutions. The differences between the spectra are explained by the change in the vapor–gas content of the bubbles and the nature of their population, from large and non-inertial to small and pulsating inertially.
Theoretical Study of the Hydrolysis of Iron–Sulfur–Nitrosyl Complex [Fe(NO)2(SCH2)2]+
Authors: Luzhkov V. B. , Krapivin V. B. , Sanina N. A. , Aldoshin S. M.
Published: April 2024

The mechanisms of hydrolysis of a model iron–sulfur–nitrosyl complex (ISNC) [Fe(NO)2(SCH2)2]+ 1 with thioformaldehyde ligands have been studied using the density functional theory and polarizable continuum model of water. Quantum chemical calculations employed the TPSSH and M06 functionals and def2-TZVP basis set and took into account interactions with water medium. Hydrolysis of 1 was found to be an exothermic process with small activation energy whereas exchange of NO for H2O is thermodynamically unfavorable. The calculations have predicted lower activation barrier for the associative mechanism with concerted replacement of SCH2 by H2O than for dissociative mechanism with homolytic bond cleavage of the Fe–S coordination bond in water. The mechanism of hydrolysis that involves participation of OH– was found to be less probable at pH 7. The calculation results show that ISNC 1 is of {Fe1+(NO•)2}9 type and retains its tetrahedral structure that is typical for crystals of ISNC with thiocarbonyl ligands.
Indolo[3,2-b]carbazole Derivatives Exhibiting Hole Conductivity in Organic Light-Emitting Diodes
Authors: Steparuk A. S. , Kazin N. A. , Tolshchina S. G. , Irgashev R. A. , Zhilina E. F. , Aleksandrov A. E. , Lypenko D. A. , Sayarov I. R. , Tameev A. R. , Rusinov G. L.
Published: April 2024

A study is performed of the photophysical properties of indolo[3,2-b]carbazole-based compounds synthesized earlier. The charge carrier mobility in the space charge-limited current mode and the energy levels of the highest occupied and lowest unoccupied molecular orbitals in the compounds are determined. It is shown that indolo[3,2-b]carbazole derivatives can be used as hole transporting layers in organic light-emitting diodes.
Investigation of the Pore Structure of Exfoliated Graphite Based on Highly Oriented Pyrolytic Graphite Nitrate
Authors: Krautsou A. V. , Shornikova O. N. , Bulygina A. I. , Solopov A. B. , Kustov A. L. , Avdeev V. V.
Published: April 2024

Graphite intercalated compounds (GICs) with different stage numbers were prepared from highly oriented pyrolytic graphite (HOPG) and nitric acid using a chemical method. Exfoliated graphite (EG-T) was synthesized from GICs by water treatment followed by thermal shock. The effects of the graphite oxidation depth on the EG-T thermal expansion coefficient, volatile content, and total porosity were examined. However, the main purpose of this work was investigation of the dependence of the inner EG-T pore structure on the level of oxidation. Thus, we studied the micro- and mesopore structure and specific surface area by nitrogen porosimetry and the modern 2D-NLDFT method to calculate the pore size distribution and pore volume. As well, we performed a mercury porosimetry experiment to determine the macropore characteristics. We examined the pore space using a number of scanning electron micrographs of EG-T particle cross-sections using an image processing technique. In this way we showed the strong correlation between the EG-T pore structure parameters and oxidation depth of graphite.
Using Phase Inversion to Create Porous Spheres Based on Polysulphone
Authors: Otvagina K. V. , Maslov A. A. , Shestoperova T. A. , Ryabov S. A. , Kazarina O. V.
Published: April 2024

A procedure is developed for creating porous spheres based on polysulfone via phase inversion from a system of a mixed solvent (chloroform, n-methylpyrrolidone) and a mixed precipitant (water, ethanol).
Distribution of Charges over the Surfaces of Charged Particles of Complex Shapes while Electrospraying
Authors: Samukhina Yu. V. , Buryak A. K.
Published: April 2024

A current topical area of condensed matter physics is research in the field of structured materials that contain structures of micro- and nanoparticles. Electrospray is widely used to obtain micro- and nanoparticles. It is known to allow particles of different geometric shapes to be obtained. The authors propose an analytical procedure for obtaining a new class of nontrivial analytical solutions to the electrostatics problem of charge distribution over the surfaces of particles that can form while electrospraying. Complex nontrivial forms of this class of surfaces are considered. Exact analytical formulas are obtained for the charge distribution density over the surfaces of particles.
An Investigation of the Properties of Binary and Ternary Mixtures Containing Morpholine
Authors: Zhuchkov V. I. , Raeva V. M. , Ul’yanova A. A.
Published: April 2024

The densities of binary and ternary mixtures of morpholine with dimethyl sulfoxide and N-methyl-2-pyrrolidone are experimentally studied at 293.15 K and atmospheric pressure, density deviations and excess molar volumes of mixtures are calculated from experimental data, concentration dependences for binary systems are described by the Redlich–Kister polynomial, and density isoline diagrams of the morpholine–dimethyl sulfoxide–N-methyl-2-pyrrolidone system are plotted.
Acenaphto[1,2-k]fluoranthene: Role of the Carbon Framework Transformation for Tuning Electronic Properties
Authors: Brotsman V. A. , Lukonina N. S. , Rybalchenko A. V. , Kosaya M. P. , Ioffe I. N. , Lysenko K. A. , Sidorov L. N. , Pshenichnyuk S. A. , Asfandiarov N. L. , Goryunkov A. A.
Published: April 2024

Acenaphtho[1,2-k]fluoranthene (1) is synthesized via tandem cyclization during the dehydrofluorination of 1,4-di(1-naphthyl)-2,5-difluorobenzene (2) on activated γ-Al2O3. Presence of residual hydroxyl groups in alumina reduce the yield of target product 1 because of the side hydrolysis of fluoroarenes with the formation a product of partial cyclization, 9-(1-naphthyl)fluoranthen-8-ol (1b). The formation of negative ions (NI) of compounds 1 and 2 in the gas phase is studied by means of dissociative electron attachment (DEA) spectroscopy. Long-lived molecular NIs 1 and 2 are registered at the thermal energies of electrons, and patterns of their fragmentation are established. The adiabatic electron affinities of compounds 1 and 2 are estimated in the Arrhenius approximation and equal 1.17 ± 0.12 and 0.71 ± 0.07 eV, respectively, which agree with data from quantum chemical modeling at the level of the density functional theory (DFT). Electronic transitions for compounds 1 and 2 are studied via optical absorption and fluorescence spectroscopy. Fluorescence quantum yields are measured, and the resulting data are interpreted according to the time dependent DFT. The electrochemical properties of compounds 1, 1b, and 2 are studied via cyclic voltamperometry, and the levels of boundary molecular orbitals are estimated on the basis of their formal potentials of reduction and oxidation.
Crystallization of Magnetic Iron Oxide Nanoparticles during Chemical Synthesis from Iron Salt Solutions with Exposure to Ultrasound
Authors: Nikolaev A. M. , Kovalenko A. S. , Frolov K. V. , Kopitsa G. P. , Baranchikov A. E. , Shilova O. A.
Published: April 2024

Iron oxide nanopowders are synthesized via chemical precipitation. It is shown that synthesis produces an iron oxide phase with a magnetite structure (either a magnetite–maghemite solid solution or a mixture of this solid solution and goethite). The sizes of the CSR and particles for the main phase are ~10–20 nm. The synthesized iron oxide powders have developed surfaces, specific surface area SBET ≈ 92 and 117 m2/g, and identical fairly large specific pore volumes (VP/P0→0.99/0→0.99 = 0.35 cm3/g). It is shown that additional in situ ultrasonic treatment of the magnetic iron oxide nanoparticles in the mother liquor results in abrupt oxidation of iron(II) ions and creates a nonmagnetic impurity phase of goethite.
Electrochemical Behavior of a Gold Electrode in the Aqueous Potassium Salt of Bridging 1,2,4,5-Tetraoxane
Authors: Polyakov M. V. , Vedenyapina M. D. , Skundin A. M. , Yaremenko I. A. , Radulov P. S. , Kuznetsov V. V.
Published: April 2024

The behavior of a smooth gold electrode in aqueous solutions of the potassium salt of bridging 1,2,4,5-tetraoxane containing a biperoxide cyclic fragment was studied by cyclic voltammetry. The cathode process was analyzed in detail. It was shown that the process involves four electrons. The products of electrolysis of the potassium salt were studied, and a reaction mechanism was proposed.
Effect of Chitosan on the Electronic State and Distribution of Rhodium on the Zeolite Catalyst Surface According to Data on IR Spectroscopy of Adsorbed Carbon Monoxide
Authors: Shilina M. I. , Obukhova T. K. , Batova T. I. , Kolesnichenko N. V.
Published: April 2024

Zeolite catalysts for the conversion of dimethyl ether to light olefins with a monoatomic distribution of rhodium are studied via infrared spectroscopy of the diffuse reflection of adsorbed carbon monoxide and X-ray absorption spectroscopy. The zeolite is preliminarily treated with ultrasound to obtain a monatomic distribution of the active component on the support’s surface, and a polymer (chitosan hydrochloride) is used as the medium for dispersing rhodium at the stage of impregnation. A sample prepared via the traditional impregnation of zeolite with an aqueous solution of rhodium chloride is studied for purposes of comparison. It is shown that rhodium in the structure of zeolite treated with ultrasound is in the form of isolated metal centers whether it is deposited with or without a polymer. Synthesis with chitosan results in a more disperse distribution of rhodium on the outer surface of the zeolite and greater oxidizing ability of the catalyst.
Specific Features of the Retention of Lutein Diesters on C16 Stationary Phases with Different Pore Diameters
Authors: Deineka V. I. , Staroverov S. M. , Vasiyarov G. G. , Burzhinskaya T. G. , Blinova I. P.
Published: April 2024

It is shown that the column dead time determined from the retention of uracil is longer than the one determined from the retention of homologs—lutein diesters—for C16 reversed phases on three columns with sorbents with different pore diameters (80, 110, and 160 Å). This finding confirms the familiar assumption that the sorbate molecules 10% larger than the pore diameter can cause problems with the retention of the sorbate. It is found for smaller molecules (of alkyl benzoates) that the dead time determined from the retention of uracil is less than the one determined from the retention of the homologs on the same stationary phases, confirming that the main cause of the observed effect is the size factor.
Temperature Dependence of the Oxidation of Hydrogen with Sulfur Dioxide
Authors: Gukasyan P. S. , Makaryan E. M. , Arutyunyan A. A. , Davtyan A. G.
Published: April 2024

An experimental study is performed of the mechanism of sulfur dioxide–hydrogen interaction (4Н2 + 2SО2 → S2 + 4H2О) at temperatures of 623, 673, 723, and 773 K and a pressure of 198 Torr. The mechanism is analyzed via mathematical modeling. It is found to be a chain reaction of hydrogen oxidation with sulfur dioxide, which results in the formation of molecular sulfur (S2). The process is characterized by negative Gibbs free energy ΔG723 = −49.950 kcal/mol. The potential energy surface of the (HOSO + HOSO) system is studied by various means of quantum chemistry, and the thermodynamic parameters of the НОSO + НОSO → SO + SO2 + Н2О reaction are determined. A new mechanism of the reaction, supplemented by elementary acts, is discussed. Good agreement is found between energies of activation determined experimentally and calculated using data from our numerical kinetic analysis.
Calculating the Gibbs Energy of Solvation of Pyridine in Nonaqueous Solvents
Authors: Kuz’mina I. A. , Kovanova M. A. , Perova S. O.
Published: April 2024

Gibbs energies of the solvation of pyridine (Py) in methanol, acetonitrile, and N,N-dimethylformamide are calculated via quantum chemical modeling. Contributions from universal and specific types of interaction between the Py and solvent molecules to the change in the Gibbs energies of solvation of the aromatic heterocycle are determined when alcohol is replaced with aprotic solvents.
“Chair”–“Boat” Conformational Transition of Cyclohexanone during the Oxidation of Cyclohexane
Authors: Puchkov S. V. , Nepomnyashchikh Yu. V.
Published: April 2024

The B3LYP/6-311g++(d,p), G3, and CBS-QB3 methods (DFT) have been used to calculate the free energy and equilibrium constants of the “chair”–“boat” conformational transition of cyclohexanone in the temperature range 298.15–428.15 K. The equilibrium composition of the chair and boat conformers of cyclohexanone has been calculated. It has been shown that with an increase in the proportion of the boat conformation, the selectivity of the process of cyclohexane oxidation to cyclohexanone decreases. The transition states of addition reactions of cyclohexyl hydroperoxide at the carbonyl group of cyclohexanone for chair and boat conformations have been found by the QST2 method. The energy profiles of these reactions have been calculated. It has been established that the addition of hydroperoxide to the carbonyl group of the boat conformation of the ketone is accompanied by a transition to the chair conformation.
DFT Study of Potential Barriers and Trajectory of CO2 Adsorption/Desorption As Well As Dissociation on Clusters Simulating Fe (100), Fe (110), and Fe (111) Facets
Authors: Tolkachev N. N. , Pokusaeva Ya. A. , Bogdan V. I.
Published: April 2024

Density functional theory calculations (DFT) were performed to investigate the Fe-facet effect on the CO2 potential barrier as well as trajectory of CO2 adsorption. It was found that potential barrier of CO2 adsorption on Fe (111) is almost absent (~0.01 eV). At the same time, potential barriers of CO2 adsorption on Fe (100) and Fe (110) are 0.10 and 0.26 eV, correspondingly. The most stable configuration of CO2 adsorption on different Fe facets under consideration is CO2 adsorbed on Fe (111) with heat effect –1.16 eV, whereas adsorption energies of CO2 on Fe (100) and Fe (110) are –0.87 and –0.15 eV, correspondingly. Found values are in good agreement with literature data. Most energetically favorable trajectory of the CO2 adsorption passes through 2-fold adsorption site (located near two neighbor Fe atoms) in case of flat Fe facets (100) and (110). Unexpectable tend to spontaneous dissociation of CO2 molecule on desorption stage was found at distance ~2.66 Å above Fe (100) surface. Analysis of electron spin distributions allows one to conclude that dissociation is caused by excitation of CO2 molecule accompanied with rearrangement of the spin density of the both CO2 molecule and surface Fe (100) atoms rather than charge transfer. CO2 dissociation on adsorption stage on Fe (100) facet was not found as well as it was not observed over other Fe facets both on desorption and on adsorption stages.
Database of Intermediates of Enzyme-Catalyzed Chemical Reactions ENIAD
Authors: Moskovsky A. A. , Firsov D. A. , Khrenova M. G. , Mironov V. A. , Mulashkina T. I. , Kulakova A. M. , Nemukhin A. V.
Published: April 2024

Enzymatic catalysis is characterized by multistage chemical reactions from enzyme-substrate complexes to products. In a number of cases, in the course of experimental studies, it is possible to characterize the structures and properties of intermediates of complex chemical reactions in proteins. The use of modern computer simulation methods makes it possible to significantly supplement the knowledge of the mechanisms of enzymatic catalysis reactions and provide detailed data on reaction intermediates, including structures with atomic resolution. The materials accumulated to date make it possible to create a unique dat-abase called ENIAD (ENzyme-In-Action-Databank). The article describes the principles of building the ENIAD database, as well as a multiplatform web interface for accessing data (https://lcc.chem.msu.ru/eniad/).
CALPHAD Modelling of Ag–Pd–Sn Ternary System
Authors: Pavlenko A. S. , Zhmurko G. P. , Kabanova E. G. , Kareva M. A. , Ptashkina E. A. , Kuznetsov V. N.
Published: April 2024

CALPHAD modelling of the Ag–Pd–Sn ternary system has been performed. The disordered phases, the melt and the fcc phase were described using the substitutional solution model. Sublattice models were used to describe intermetallic compounds and the ternary phase. The two-sublattice model (Ag,Pd)4(Ag, Sn) used for the ternary phase made it possible to reproduce the inclination of its homogeneity range. The results of the thermodynamic calculation of the Ag–Pd–Sn system are in good agreement with the experimental data on phase equilibria and enthalpies of formation of the liquid. The agreement with the data on the partial Gibbs energy of tin in the liquid is somewhat worse.
Hydrogenation of S6-C60(CF3)12
Authors: Romanova N. A. , Markov V. Yu. , Goryunkov A. A.
Published: April 2024

The first results of the hydrogenation of S6-symmetric trifluoromethylfullerene C60(CF3)12 in two types of reactions were reported: (1) high-temperature radical hydrogenation with 9,10-dihydroanthracene and (2) nucleophilic hydrogenation with sodium tetraborohydride under mild conditions. The high-temperature radical hydrogenation of S6-C60(CF3)12 is accompanied by partial elimination of CF3 groups and leads to the formation of a complex mixture of products of a composition C60(CF3)8–12H18–22. During the hydrogenation of NaBH4 under mild conditions, selective formation of the hydride C60(CF3)12H12 was recorded by mass spectroscopy. A kinetic analysis of the sequential nucleophilic hydrogenation of S6-C60(CF3)12 was performed, using quantum-chemical modeling at the level of density functional theory, under the assumption of linear correlation between the activation energy and the enthalpy of elementary steps of the same type. The isomeric composition was predicted for the series of anionic intermediates C60(CF3)12H−2n−12−1− and their protonation products C60(CF3)12H2n, where n = 1–6. The hydrogenation of S6-C60(CF3)12 should lead to the formation of the thermodynamically and kinetically most stable product ortho-S6-C60(CF3)12H12, in which all hydrogen atoms are located in neighboring positions near the CF3 groups, forming together with them a near-equatorial belt of 24 addends while retaining the triphenylene fragments at two opposite poles. The average bond dissociation energy BDE(C–H) in ortho-S6-C60(CF3)12H12 is 298 kJ mol–1, which is approximately 20 kJ mol–1 higher than the BDE(C–H) of known fullerene hydrides C60H18 and C60H36 (PBE0/def2-SVP).
Adsorption of Methylene Blue and Eosin Y on Opal-Cristobalite Rocks
Authors: Ubaskina Yu. A.
Published: April 2024

The adsorption of methylene blue and eosin Y on opal-cristobalite rocks has been studied. The amount of methylene blue and eosin Y adsorbed on opal-cristobalite rocks is determined by the amorphous silica and clay minerals contained in the rocks. The possibility of using the results of IR spectroscopy for accurate determination of the amorphous silica content in opal-cristobalite rocks is shown. For opal-cristobalite rocks, a higher value of the point of zero charge is associated with lower silicon and aluminum contents in them and higher total content of alkali and alkaline earth metals.
Effect of Barium on the Corrosion and Electrochemical Behavior of Lead Babbit BBa (PbSb15Sn10Ba) in a NaCl Electrolyte Medium
Authors: Ganiev I. N. , Odinaev A. Kh. , Khodzhaev F. K. , Khodzhanazarov Kh. M.
Published: April 2024

Results are presented from studying the effect barium additives (0.01–1.0 wt %) as a structure modifier have on the anodic behavior of lead babbit BBa (PbSb15Sn10Ba) in a NaCl electrolyte medium. The studies are performed using the potentiostatic technique in the potentiodynamic mode with a potential sweep rate of 2 mV/s. It is shown that the free corrosion potential of alloys shifts to the positive side over time and acquires a positive value upon an increase in the concentration of the modifier (barium) in the lead babbit. Adding barium to lead babbit BBa (PbSb15Sn10Ba) raises its corrosion resistance by 20–25%. An increase in the rate of the corrosion of alloys is noted, regardless of their composition and the concentration of NaCl in a solution. It is shown that raising the concentration of chloride ions in a NaCl electrolyte lowers the potentials of the free corrosion, repassivation, and pitting of alloys.
Rearrangement of the Conformations of Polyampholitic Macromolecules on the Surface of a Charged Spherical Metal Nanoparticle in an Alternating Electric Field: Molecular Dynamic Simulation
Authors: Kruchinin N. Yu.
Published: April 2024

The rearrangement of the conformational structure of polyampholytic polypeptides on the surface of a charged spherical gold nanoparticle with its polarity intermittently changing over time was studied using molecular dynamics modeling. The angular distributions of the polypeptide atoms, as well as the radial distributions of the macrochain atomic density in the equatorial region of the nanoparticle with differentiation according to the types of links, were calculated. The polyampholyte shell acquired an annular shape, and the resulting macromolecular ring was located around the charged nanoparticle perpendicularly to the vector of the external electric field strength. With an increase in the charge of the nanoparticle, the ring belt was ordered according to the types of macrochain links, forming concentric annular layers. The diameter of the macromolecular ring depended on the law of distribution of charged units in the macrochain. At elevated temperatures the annular macromolecular ring was deformed at the moments of the highest polarization of the nanoparticle.
Behavior of Surface-Active Substances in a Nitric Acid Medium and Prospects for Using Them in Hydrometallurgy
Authors: Lugovitskaya T. N. , Danilin L. M. , Rogozhnikov D. A. , Mamyachenkov S. V.
Published: April 2024

The behavior of surface-active substances (surfactants) is studied using the examples of lignosulfonate (LS) and sodium dodecyl sulfate (SDS) in aqueous and nitric acid media as promising additives for the nitric acid leaching of refractory ore concentrates. The effect the temperature (15–70°С) and concentrations of the surfactant (Csurfactant = 0.02–200 g/dm3) and nitric acid (CHNO3 = 0.1–10 g/dm3) have on the surface tension, critical concentration of micelles (CMC), electrical conductivity, pH, and optical density of solutions is established. The critical association of concentration is determined for lignosulfonate: CLS ~ 0.13–0.14 mol/dm3. An increase in the surface activity of lignosulfonate is noted upon raising the temperature of and adding nitric acid to an LS–H2O system. The established effects (a drop in σl–g) are explained by an increase in the coefficient of diffusion of LS macromolecules and a change in the intensity of the associative-dissociative processes of counterions and the LS polyanion. The positive effect nitric acid has on the surface activity of SDS is noted and found to reduce surface tension at the liquid–gas interface and CMCs. Associative processes in SDS–HNO3 systems are also confirmed by measuring the optical density of the considered systems.
Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions
Authors: Sizykh M. R. , Batoeva A. A.
Published: April 2024

The kinetic regularities of degradation of the azo dye methyl orange (MO) in photoinitiated oxidizing systems have been studied using a xenon lamp (UV–Vis) as a source of quasi-solar radiation. According to the efficiency and rate of dye destruction, the considered oxidizing systems can be arranged in the following series: {UV–Vis} {UV–Vis/S2O2-8} {S2O2-8/Fe0} {UV–Vis/S2O2-8/Fe0} {UV–Vis/S2O2-8/Fe2+}. It has been established that in photoinitiated Fenton-like oxidizing systems there is not only complete conversion of MO but also its deep mineralization in aqueous solution; a decrease in the content of total organic carbon reaches 60%. In this case, the specific catalytic activity of iron ions in the combined system {UV–Vis/S2O2-8/Fe0} is much higher than in {UV–Vis/S2O2-8/Fe2+}. Using inhibitors of radical reactions, it has been proved that in the combined system {UV–Vis/S2O2-8/Fe0} both hydroxyl and sulfate anion radicals take part in oxidative degradation. An inhibitory influence of anions (bicarbonates, chlorides, nitrates, and sulfates) and natural dissolved organic matter (Suwanee River 2R101N) on the process of mineralization of total organic carbon during oxidative destruction of MO in the combined system {UV–Vis/S2O/Fe0} has been found.
Electrical Conductivity and Thermodynamics of Ion Association of Ammonium Ionic Liquids in Acetone
Authors: Zhuravlev O. E. , Kaftanov A. D. , Yulmasov G. S.
Published: April 2024

The electrical conductivity of a number of tetraalkylammonium ionic liquids with tetrafluoroborate anion has been studied in acetone in the temperature range 298–313 K. Based on the obtained conductometric data for the compounds under study, the Lee–Wheaton method has been used to calculate the ion association constants (Ka), limiting molar electrical conductivities (λ0), and Gibbs association energy (ΔG0) in solutions. From the temperature dependence of equivalent electrical conductivity, the values of association enthalpy (ΔH0) and entropy (ΔS0) have been calculated. For all studied compounds, the Walden–Pisarzhevsky product has been calculated. Conclusions are drawn about the influence of the structure of the studied ionic liquids on the thermodynamic parameters of association in acetone solutions.
A PACKAGE OF PROCEDURES AND FUNCTIONS FOR CONSTRUCTIONS AND INVERSION OF ANALYTIC MAPPINGS WITH UNIT JACOBIAN
Authors: SADYKOV T. M.
Published: April 2024

The set of polynomial mappings of n-dimensional complex space into itself the Jacobian matrix of which has a constant nonzero determinant is known to be very vast in any dimension that exceeds one. The well-known Jacobian conjecture states that any such mapping is polynomially invertible. Even though the computation of the determinant of the Jacobian matrix is very well supported in modern computer algebra systems, the algorithmic inversion of a polynomial mapping is still a problem of considerable computational complexity. In this paper, we present a Mathematica package JC that can be used for construction and inversion of polynomial mappings and more general analytic mappings with the unit determinant of the Jacobian matrix. The package includes functions that allow one to algorithmically construct these mappings for a given dimension of the space of variables and a given degree of mapping components. The package, together with a library of datasets for testing it and results of computational experiments, is available for free public use at https://www.researchgate.net/publication/358409332_JC_Package_and_Datasets.
SYMBOLIC ALGORITHM FOR FINDING ZEROS OF A SYSTEM OF
OLOMORPHIC FUNCTIONS
Authors: KUZOVATOV V. I. , KYTMANOV A. A. , MYSHKINA E. K.
Published: April 2024

Based on the Bochner–Martinelli integral representation, an algorithm for determining the number of zeros of a system of holomorphic functions is developed. We search for zeros of the system in a polycube. The use of computer algebra methods in this problem is due to the computational complexity of the developed algorithms and final results. The algorithm is implemented in Maple, which makes it possible to significantly facilitate the necessary computations.