bluuebunny/crossref_metadata_2025 huggingface dataset:
Correction of the 3D Computer Model of the Phase Diagram for the LiCl–PrCl3–KCl System Using Thermoanalytical Curves
Authors: Vorob’eva V. P. , Zelenaya A. E. , Lutsyk V. I. , Parfenova M. D. , Baldanov V. D.
Published: April 2024

A spatial (3D) computer model of an isobaric phase diagram of the LiCl–PrCl3–KCl system was designed. The model was assembled of 66 surfaces and 27 phase regions, of which 31 surfaces and 14 phase regions degenerate to verticals or vertical planes because of the limited solubilities of the initial chlorides and their compounds. Published experimental isothermal sections and thermoanalytical curves for 33 salt melts were used to improve the quality of the 3D model. The results can be used to improve the molten-salt refining technology of nuclear fuel waste.
Isomeric Molecular Forms of Pseudo-Binuclear Bismuth(III) Dithiocarbamate [Bi2{S2CN(CH2)6}6]: Preparation, Thermal Behavior, and Structural Effect of Its Solvation with DMSO, [Bi2{S2CN(CH2)6}6]⋅2(CH3)2SO
Authors: Novikova E. V. , Egorova I. V. , Isakovskaya K. L. , Ivanov A. V.
Published: April 2024

Bismuth(III) hexamethylenedithiocarbamate (HmDtc) [Bi2{S2CN(CH2)6}6] (I) and its solvated with dimethyl sulfoxide form [Bi2(S2CNHm)6]⋅2(CH3)2SO (II) have been obtained. The crystal structure of compound I shows an unusual alternation of two unsymmetrical isomeric pseudo-binuclear [Bi1/1B(HmDtc)3···Bi1A/1C(HmDtc)3] molecules, each of which involves two non-equivalent mononuclear moieties combined by secondary Bi···S bonds. The solvation of complex I leads to the structural unification of isomeric [Bi(HmDtc)3] molecules followed by their self-organization into centrosymmetric pseudo-dimers in the structure of compound II. All HmDtc ligands coordinate in S,S'-anisobidentate mode to form four isomeric (in I) or structurally unique [Bi(HmDtc)3] molecules (in II), whose distorted polyhedra can be approximated by pentagonal pyramid or octahedron. Solvating DMSO molecules are retained in the structure II by C–H···O hydrogen bonds. The analysis of energy dispersive X-ray spectra allowed one to identify the residual matter obtained by thermolysis of the complexes as Bi2S3 with admixture of Bi0.
Synthesis of Nickel(II) Complexes Based on Dialkylphosphorylpyridines and Their Cytotoxic Activity
Authors: Enikeeva K. R. , Kasimov A. I. , Litvinov I. A. , Lyubina A. P. , Voloshina A. D. , Musina E. I. , Karasik A. A.
Published: April 2024

Bis-chelate nickel complex of composition [L2Ni(H2O)2](BF4)2 (4), where L = 1,3-dibenzhydryl-5-(pyridin-2-yl)-5-oxo-1,3,5-diazaphosphorinane, and tris-chelate complexes 5 and 6 of composition [L3Ni](BF4)2, where L = 2-diethylphosphorylpyridine and 2-diisopropylphosphorylpyridine, based on 1,4-N,O ligands L2–L4 with phosphoryl groups of acyclic and cyclic structure have been prepared. The structure and composition of complexes 4–6 were confirmed by mass-spectrometry, IR spectroscopy, thermogravimetric and elemental analysis. The structure of complexes 4-EtOH and 5 in crystals has been established by X-ray diffraction study. Cytotoxic properties toward M-HeLa and HuTu80 cancer cells and Chang Liver normal cell lines for the previously prepared nickel(II) complexes 1–3 based on 2-(oxophospholane)pyridines and the nickel(II) complexes obtained in this work have been studied. It has been found that the complexes with ligands containing cyclic phosphoryl groups show higher cytotoxicity toward cancer cells as compared with the complexes with their acyclic analogs.
Antioxidant Activity of Conjugates of Cerium Dioxide Nanoparticles with Human Serum Albumin Isolated from Biological Fluids
Authors: Sozarukova M. M. , Proskurnina E. V. , Baranchikov A. E. , Ivanov V. K.
Published: April 2024

For the first time, an analysis was made of the antioxidant properties of conjugates of CeO2 nanoparticles with human serum albumin (CeO2@HSA), including HSA isolated from blood plasma and biological fluids similar in composition to blood plasma, namely, peritoneal (ascitic) and synovial (articular) fluids. The antioxidant activity of hybrid nanomaterials was studied in relation to alkylperoxyl radicals by luminol-dependent chemiluminescence. It was shown that the interaction of CeO2 nanoparticles with purified human serum albumin is accompanied by a decrease in the antioxidant and prooxidant potential of albumin by a factor of ⁓1.5. Presumably, this is caused by the interaction of nanodispersed CeO2 with sulfhydryl groups of the protein. Conjugates of CeO2 nanoparticles with albumin isolated from biological fluids (CeO2@HSA) exhibit a synergistic antioxidant effect. In this case, the mechanism of antioxidant activity is fundamentally different from that for CeO2 sols modified with purified human serum albumin. According to quantitative assessment, the antioxidant capacity of CeO2@HSA conjugates is ⁓20 times lower than that of Trolox, a water-soluble analog of vitamin E.
Features of Cadmium(II) Complexation with N-Donor Heterocyclic Ligands in the Presence of the Octadecahydroeicosaborate Anion
Authors: Avdeeva V. V. , Kubasov A. S. , Nikiforova S. E. , Goeva L. V. , Malinina E. A. , Kuznetsov N. T.
Published: April 2024

The process of cadmium(II) complexation with 1-ethyl-2-(4-methoxyphenyl)azobenzimidazole (L1), 2,2′-bipyridyl (L2), and 1,10-phenanthroline (L3) in the presence of the [trans-B20H18]2– anion has been studied. It has been found that the nature of the organic ligand affects the composition and structures of the resulting compounds. Complexation with ligand L1, a benzimidazole derivative, has yielded binuclear complex [CdL12NO3(μ-NO3)CdL1(NO3)2] (1), which contains no boron cluster anion. In the case of azaheterocyclic ligands L2 and L3, depending on the Cd : L ratio, heteroleptic complexes [CdL2NO3]2[trans-B20H18] (L = L2 (2); L3 (3)) with coordinated nitrate ions (Cd : L = 1 : 2) or tris-chelate complexes [CdL3][trans-B20H18] (L = L2 (4); L3 (5)) with the boron cluster anion as a counterion (Cd : L = 1 : 3) have been isolated. The structures of complexes [CdL12NO3(μ-NO3)CdL1(NO3)2] (1) and [Cd(L2)2NO3]2[trans-B20H18] (2) have been determined by X-ray diffraction.
Solubilities of Components in the Сa(ClO3)2∙NH4Сl–H2O System
Authors: Rakhmonov O. O. , Sidikov A. A. , Shukurov Zh. S. , Togasharov A. S.
Published: April 2024

The Сa(ClO3)2∙NH4Сl–H2O system has been studied in its constituent binary systems and seven inner sections, and its polythermal solubility diagram has been plotted in the range of temperatures from–42.5 to 87.5°С. The solubility diagram features the crystallization fields of ice; calcium chlorate hexahydrate, tetrahydrate, and dihydrate; and ammonium chloride. Three ternary points exist in the system. The system belongs to the complex eutonic type; its components retain their individuality and show good solubility in water. In the [40% Сa(ClO3)2 + 60% H2O]–[NH4Сl] section of the studied system, variations in crystallization temperature, viscosity, density, pH, and refractive indices of the solution have been determined. The thus-obtained results have been used to plot the composition–property diagram of the [40% Сa(ClO3)2 + 60% H2O]–[NH4Сl] section of the Сa(ClO3)2∙NH4Сl–H2O system.
Thermophysical Properties of Lanthanum and Samarium Zirconate—Hafnates
Authors: Gagarin P. G. , Guskov A. V. , Guskov V. N. , Khoroshilov A. V. , Gavrichev K. S.
Published: April 2024

The synthesis and identification of lanthanum and samarium zirconate–hafnates of the pyrochlore structure type have been reported. The heat capacity of the samples in the temperature range 310–1380 K was measured by the differential scanning calorimetry method. The temperature dependences of the cubic lattice parameters were determined, and the thermal expansion coefficients were evaluated in the range 298–1273 K using high-temperature X-ray powder diffraction. The thermal diffusivity of the samples was measured by the laser flash method, and the temperature dependences of the thermal conductivity were calculated considering the porosity of the samples.
Phase Diagram of the MgF2–SrF2 System and Interactions of Magnesium and Strontium Fluorides with Other Fluorides
Authors: Alexandrov A. A. , Chernova E. V, , Nishchev K. N. , Fedorov P. P. , Pynenkov A. A. , Uslamina M. A. , Ushakov S. N. , Voronov V. V.
Published: April 2024

The phase diagram of the SrF2–MgF2 system has been studied by differential thermal analysis (DTA) and X-ray powder diffraction (XRD). The stability area of the compound SrMgF4 is very small, and its extent is about 20°С between 870 and 890°С. The formation of compounds by magnesium fluoride and strontium fluoride with other metal fluorides is considered in the M versus X coordinates, where M is the cumulative moment of the cation and X is the cation electronegativity. Two areas of compound formation were identified for each of the fluorides. Magnesium and strontium fluorides are amphoteric compounds in terms of the Lewis acid and base theory.
Thermochemical Study of Bismuth Cobalt Dysprosium Oxide: The Enthalpy of Formation and Lattice Enthalpy
Authors: Matskevich N. I. , Semerikova A. N. , Gel’fond N. V. , Zaitsev V. P. , Matskevich M. Yu. , Anufrieva O. I. , Fedorov A. A.
Published: April 2024

Bismuth cobalt dysprosium oxide of composition Bi12.5Dy1.5CoO22.325 has been prepared by solid-state reactions. The compound has a cubic structure (space group Fmm) with the unit cell parameter a = 0.55279(5) nm. The solution enthalpy and standard enthalpy of formation of Bi12.5Dy1.5CoO22.325 have been measured by solution calorimetry: ΔsolH0 = −1017.0 ± 7.5 kJ/mol, and ΔfH0 = −5338.8 ± 19.9 kJ/mol. The lattice enthalpy has been calculated using the Born–Haber cycle: ΔlatH0 = −99020 kJ/mol. The lattice enthalpy increases in magnitude as the lanthanide radius decreases in the neodymium–dysprosium–holmium series.
Epoxide-Mediated Synthesis of Two-Component Al2O3–TiO2 Aerogels and Their UV-Protective Characteristics
Authors: Polevoi L. A. , Kolesnik I. V, , Kopitsa G. P. , Golikova M. V. , Tsvigun N. V. , Khamova T. V. , Sergeeva A. V. , Gorshkova Yu. E. , Sandzhieva D. A. , Ubushaeva B. V. , Baranchikov A. E. , Ivanov V. K.
Published: April 2024

A new method was proposed to synthesize aerogels based on Al2O3–TiO2 by the hydrolysis of mixed solutions of titanium tetrachloride and aluminum nitrate in the presence of propylene oxide, followed by supercritical drying of the obtained gels. The aerogels are characterized by a high specific surface area (140–500 m2/g) and a high specific porosity (1.7–2.7 cm3/g). Heat treatment of the Al2O3–TiO2 aerogels at temperatures up to 600°C does not lead to crystallization of titanium dioxide, whereas the formation of crystalline anatase in aerogels based on individual TiO2 is observed already at a temperature of 450°C. Using the standardized ISO 24443-2016 method, the SPF value of the obtained materials was determined, which turned out to be comparable to the characteristics of a commercial inorganic UV filter based on TiO2 (Kronos 1171). At the same time, the photocatalytic activity of the Al2O3–TiO2 aerogels turned out to be more than 120 times lower than the similar characteristics of the commercial UV filter based on titanium dioxide. The results obtained demonstrated that the Al2O3–TiO2 aerogels are promising as components of sunscreens.
Phase Equilibria Involving Solid Solutions in the Li–Eu–O System
Authors: Buzanov G. A. , Nipan G. D.
Published: April 2024

Phase equilibria involving solid solutions in the Li–Eu–O system in an oxidizing, inert, and reducing atmospheres during annealing mixtures of various precursors subjected to preliminary mechanochemical activation at temperatures of 400–1100°C and partial pressures~ 21 and 0.01 kPa and ~ 5 kPa have been studied by X-ray powder diffraction and thermogravimetry. The solubility of lithium in EuO has been first estimated, which is no less than 50–60%. For Eu2O3 and, it is 30% of the total amount of cations. Along with LiEuO2, the formation of crystalline mixed-valent (EuII + EuIII) phases LiEu3O4 and Li2Eu5O8 has been confirmed. The thermal behavior of solid solutions Eu1 – xLixO1 – δ based on europium monoxide and Li1 + yEu3O4 – γ in air has been studied. The concentration phase diagram of the Li–Eu–O system has been constructed.
Potentiometraic Method for Determining Biologically Non-Degradable Antimicrobial Substances
Authors: Turyshev E. S. , Kubasov A. S. , Golubev A. V. , Zhizhin K. Yu. , Kuznetsov N. T.
Published: April 2024

Ion selective electrodes (ISEs) based on polymer plasticized membranes have been developed for the determination of benzalkonium chloride (alkyldimethylbenzylammonium), the active component being cesium bis-octodecyl-2-sulfonio-closo-decaborate Cs[B10H9S(C18H37)2] (sensor A). For the determination of norfloxacin hydrochloride, the active component is potassium tris-octodecyl-1-ammonio-closo-decaborate K[B10H9N(C18H37)3] (sensor B). It has been shown that the electrodes have a reversible potentiometric response with respect to the analyzed cations in the presence of a number of other inorganic and organic cations. The influence of the concentration of the electrode-active substance on the electrochemical characteristics of the manufactured sensor has been studied. The optimal composition of the ion-sensitive membrane has been found. It has been determined that the developed sensors provide a wide range of detectable concentrations (for sensor A, 2 × 10–7–1 × 10–2; for sensor B, 1 × 10–7–1 × 10–2) and a low detection limit (for sensor A, 1 × 10–7 M; for sensor B, 8 × 10–8 M). New ISEs can be recommended for direct potentiometric detection of free ions in water bodies and water extracts of soils.
Glutamate and GABA receptors in non-neural animals (Placozoa): Preadaptation to neural transmission
Authors: Nikitin M. A. , Borman S. I.
Published: April 2024

Origins of neural system is one of the major transitions in planetary evolution. Many details of these transitions are still unknown. In particular, high diversity of neurotransmitters lacks convincing explanation so far. We analyze homologues of neuronal glutamate and gamma-aminobutyric acid (GABA) receptors of Placozoa – animal phyla lacking neurons but displaying motility and complex behaviour. Phylogenetic analysis and comparison of amino acids in ligand-binding pockets show that glutamate and GABA-like receptors of Placozoa are surprisingly numerous, diverse and fast-evolving. All these traits are characteristic of odorant rather than neurotransmitter receptors of higher animals. We argue that chemoreception system was an important source of diverse receptors for emerging nervous system to recruit, and that amino acid neurotransmitters (glutamate, GABA, glycine) were relevant external stimuli for early animals before the emergence of nervous system.
Impact of litter burning on alpine Festuca varia grasslands of the Northwestern Caucasus
Authors: Onipchenko V. G. , Bostanova F. S. , Tokareva O. A. , Makarov M. I. , Elumeeva T. G. , Akhmetzhanova A. A. , Tekeev D. K. , Malysheva T. I. , Kadulin M. S.
Published: April 2024

Fires play an important role in structure and function of terrestrial ecosystems, but their long-term impact on the composition and structure of plant communities in humid high mountain regions remains almost not studied. At the most dry alpine grasslands, dominated by a dense-tussock grass Festuca varia, with substantial accumulation of non-decomposed litter, the 23-years long experiment with regular (every two years) litter burning was established. The composition of plant community changed significantly. The mortmass (mass of litter), aboveground vascular plant biomass and relative abundance of dominants decreased substantially. In aboveground biomass the proportion of grasses decreased and that of forbs increased. The shoot numbers of Anthemis cretica, Campanula collina, Deschampsia flexuosa, Festuca ovina, Nardus stricta, and Veronica gentianoides increased after burning. Two-fold increase of alpha-diversity of vascular plants was observed on plots with burning treatment, it was twice as high as initial value, and was significantly higher than the values in the control plots. Long-term burning did not substantially change mean P, Ca and Mg content in the biomass of the most of studied species, only K content decreased in some species, while Mg content increased in Festuca varia and Nardus stricta. The increase of P and Mg content in the mortmass was observed. During long-term burning, weak soil acidification and the decrease of Ca content, as well as strong decrease of nitrogen content and the intensity of nitrogen transformation processes were observed. Generally, the observed patterns were similar to those in other studied herb communities, however, the decrease of K content during the regular burning was not reported earlier.
2E,2′E)-2,2′-(1,2,4-Thiadiazole-3,5-diyl)bis[3-arylacrylonitriles]: Synthesis and Antidote Activity with Respect to 2,4-D Herbicide
Authors: Dahno P. G , Dotsenko V. V , Strelkov V. D , Vasilin V. K , Aksenov N. A , Aksenova I. V
Published: April 2024

Oxidation of ( Е )-3-aryl-2-cyanothioacrylamides under the action of the Et2S(O)-HCl system leads to the formation of (2 Е ,2' E )-2,2'-(1,2,4-thiadiazole-3,5-diyl)bis[3-arylacrylonitriles] in 54-91% yields. Structure of the obtained compounds was confirmed by the two-dimensional NMR spectroscopy data. A plausible reaction mechanism was discussed. Two compounds showed a pronounced antidote effect against 2,4-D herbicide in a laboratory experiment on sunflower seedlings in the absence of growth-stimulating activity.
Synthesis, structure, and properties of 2-oxo-3-formylquinolone acylhydrazone containing a trimethylammonium fragment and also of transition metal complexes based on this compound
Authors: Popov L. D , Tupolova Yu. P. , Vlasenko V. G , Borodkin S. A , Levchenkov S. I , Lebedev V. E , Askalepova O. I , Borodkin G. S , Zubenko A. A , Gishko K. B. , Zubavichus Ya. V. , Lazarenko V. A. , Shcherbakov I. N.
Published: April 2024

The product of 3-formyl-2-quinolone condensation with trimethylammonium chloride acethydrazide, (H2L+)Сl- hydrazone, was synthesized. Complexes of Zn(II) and Cu(II), [M(HL)OCH3]ClO4, with a distorted square-planar strucrure of coordination sites and asymmetric chelate сomplexes of Mn(II), Ni(II), and Co(II), [M(HL) (H2L)]·(ClO4)3, of pseudo-octahedral structure were obtained on its basis. The protistocidal, antibacterial, and fungistatic activities of the synthesized compounds were studied.
High-temperature synthesis of cobalt nanoparticles in hyperbranched polyester polyol medium
Authors: Kutyreva M. P , Burmatova A. E , Khannanov A. A , Evtugin V. G
Published: April 2024

The synthesis of CoNPs cobalt nanoparticles by the method of polyol- process was proposed, which consists in a high-temperature synthesis of polymer-stabilized metal nanoparticles in a matrix of a fourth-generation hyperbranched polyester polyol. Branched polyester polyol acts as both a reducing agent and a stabilizer at the same time. It has been found that the reduction of the precursor CoCl2 with a hyperbranched polyester polyol occurs at 210°C. The introduction of NaOH into the reaction mixture makes it possible to lower the synthesis temperature by 50°C and leads to a change in the mechanism of in situ ripening CoNPs from the digestive mechanism to direct Ostwald ripening.
Synthesis and some transformations of 4-(2,5-dihydro-2,5dioxo-1h-pyrrrol-1-yl)benzoic and -phenylacetic acids amides
Authors: Kolyamshin O. A , Mitrasov Yu. N. , Danilov V. A , Pylchikova Yu. Yu. , Avruyskaya A. A
Published: April 2024

The reactions of 4-aminobenzoic and 4-aminophenylacetic acids amides with maleic anhydride yielded the corresponding monoamides of maleic acid, the cyclization of which gave amides of 4-(2,5-dihydro-2,5-dioxo1 H -pyrrol-1-yl)benzoic and 4-(2,5-dihydro-2,5-dioxo-1 H -pyrrol-1-yl)phenylethanoic acids. Their reactions with secondary amines afforded the corresponding 4-(3-dialkylamino-2,5-dioxo-2,3,4,5-tetrahydro-1 H -pyrrol-1-yl) benzoic and 4-(3-dialkylamino-2, 5-dioxo-2,3,4,5-tetrahydro-1 H -pyrrol-1-yl)phenylethanoic acids amides.
Regioselective synthesis of quercetin and myricetin derivatives
Authors: Pechinskii S. V , Kuregyan A. G , Oganesyan E. T
Published: April 2024

A regioselective method for the synthesis of esters of quercetin and myricetin at the hydroxy group in the 3 position was developed. As acids participating in the esterification reaction, 2-hydroxybenzoic (salicylic), 4-hydroxybenzoic, 2,6-dihydroxybenzoic, 3,4-dihydroxybenzoic (procatechuic), 3,4,5-trihydroxybenzoic (gallic) acids were used. A new series of quercetin and myricetin esters were obtained.
Synthesis of novel tetrahydropyrimidines via the reaction of sodium [1-(3,3-diethoxypropyl)ureido]methansulfonates with C-nucleophiles
Authors: Smolobochkin A. V , Yakhshilikova L. J , Rizbayeva T. S , Gazizov A. S , Burilov A. R , Pudovik M. A
Published: April 2024

A series of new substituted tetrahydropyrimidines was obtained by the reaction of sodium [1-(3,3-diethoxypropyl)ureido]methansulfonates with various C -nucleophiles (4-chlororesorcinol, sesamol, 2,4-dihydroxybenzoic acid, 4-hydroxy-6-methyl-2 H -pyran-2-one) in chloroform in the presence of trifluoroacetic acid.
Synthesis of new derivatives of 2-imino-2,5-dihydrofurans containing 4-oxothiazolidine ring
Authors: Karapetyan L. V , Tokmajyan G. G
Published: April 2024

The reactions of 5,5-dialkyl- N -alkyl-2-imino-2,5-dihydrofuran-3-carboxamide thiosemicarbazones with diethyl acetylenedicarboxylate and maleic anhydride in absolute ethanol gave rise to potentially bioactive compounds containing iminodihydrofuran and 4-oxothiazolidine rings. The synthesized compounds were characterized by 1H and 13C NMR spectroscopy and elemental analysis data.
Hydrogermylation of allylsilanes and -germanes
Authors: Lakhtin V. G , Efimenko D. A , Shestakova A. K , Filippov A. M , Sokolskaya I. B , Kirilina N. I , Storozhenko P. A
Published: April 2024

The reactions of hydrogermylation of allylsilanes and -germanes R3MAll (M = Si, Ge; R = Cl, EtO, Me) by hydridgermanes R3GeH (R = Cl, Me) and trichlorogermane ether 2Et2O·HGeCl3 were studied. It has been established that small amounts of mono- (β- and γ-adducts) and double germylation products and, mainly, polymers are formed in reactions with ether. During hydrogermylation of Me3SiAll with trichlorogermane, insignificant amounts of β-adduct were recorded, but mainly in the entire series of experiments with Cl3GeH, γ-adducts are formed. In the catalytic reactions of allylsilanes and -germanes with trimethylgermane, exclusively γ-adducts are formed regardless of the framing of silicon and germanium atoms. A scheme of the possible course of the studied reactions is proposed. The identification of synthesized compounds was carried out using the methods of gas-liquid chromatography, 1Н, 13С NMR spectroscopy and chromatography-mass spectrometry
Structure and stability of group 13/15 hydrides stabilized by Lewis acids and Lewis bases
Authors: Pomogaeva A. V , Lisovenko A. S , Timoshkin A. Y
Published: April 2024

Structural and thermodynamic characteristics of donor-acceptor complexes LA·E′H2EH2·LB(E = B, Al, Ga; E′ = P, As, Sb; LB = SMe2, NMe3);LA- Lewis acids of group 13 elements ER3 (E = B, Al, Ga; R = H, Me, F, Cl, Br, I, C6F5) and transition metal carbonyls Fe(CO)4, M(CO)5, (M = Cr, Mo, W), CpMn(CO)2 were computed by quantum chemical B3LYP-D3/def2-TZVP method. It is shown that removal of the Lewis base is less endothermic than removal of Lewis acid. Stability trends of the complexes depending on group 13/15 elements and Lewis acids were established. Tungsten pentacarbonyl has the highest stabilization effect.
Synthesis and biological activity of 4-aryl-2-hydroxy-4-oxo-N-(2-sulfamoylphenyl)but-2-enamides
Authors: Gein V. L , Nazarets O. V , Romanova A. V , Bobrovskaya O. V , Novikova V. V , Makhmudov R. R , Balyukina L. A
Published: April 2024

The reaction of methyl esters of 4-aryl-2-hydroxy-4-oxobut-2-enoic (aroylpyruvic) acids with 2-aminobenzenesulfonamide in glacial acetic acid in the presence of anhydrous sodium acetate, 4-aryl-2-hydroxy-4-oxo N -(2-sulfamoylphenyl)but-2-enamides were obtained. The analgesic and antimicrobial activity of the obtained compounds was studied.
n-(chlorodimethylsilyl)methylated derivatives of N,N′-propyleneurea. ir spectra analysis and quantum-chemical calculations
Authors: Chipanina N. N , Oznobikhina L. P , Lazareva N. F
Published: April 2024

The IR spectra of N -silylmethylated derivatives of N , N ′-propyleneurea in solvents of different polarity were studied in a wide temperature range. The DFT method was used to perform quantum chemical calculations of geometric, energy and spectral characteristics of these compounds in isolated state (gas) and polar medium (DMSO). Analysis and comparison of these results made it possible to evaluate the influence of the environment on the criteria for the formation and strength of intramolecular dative C=O→Si bonds. The dependence of the dative bond О→Si and the order of the bonds C=O and C-N, including of the carbon atom of the C=O group, on the interaction energy of the LEP of the oxygen atom of the carbonyl group with σ*-orbitals of axial Si-Cl ax and C-N bonds, as well as interactions of LEP of nitrogen atoms with σ*-orbitals of the C=O and C-N bonds.
Synthesis and fluorescence properties of salts of cyclic amines with tetracyanobutadiene-containing pyridine
Authors: Chunikhin S. S , Ershov O. V
Published: April 2024

A method was developed for the preparation of six new salts based on cyclic amines and pyridine containing a tetracyanobutadiene fragment, 2-(dicyanomethylidene)-5-methyl-6-phenyl-1,2-dihydropyridine-3,4-dicarbonitrile, acting as an organic anion. Correlations between the parameters of solid-phase emission of the synthesized compounds and the structure of the cation included in the composition were characterized.
Synthesis and properties of metal complexes with halogen-substituted octaphenyltetraazaporphyrins
Authors: Chizhova N. V , Likhonina A. E , Mamardashvili N. Z
Published: April 2024

Mg(II)-octa-(4-chlorophenyl)tetraazaporphyrin, Mg(II)-octa-(4-fluorophenyl)tetraazaporphyrin, Zn(II)octa-(4-chlorophenyl)tetraazaporphyrin and Zn(II)-octa-(4-fluorophenyl)tetraazaporphyrin were synthesized by cyclization of di-(4-halophenyl)maleinonitriles with magnesium and zinc(II) acetates in refluxing ethylene glycol. Zn(II)-Octaphenyltetraazaporphyrin was obtained by cyclization of diphenylmaleininitrile with zinc acetate in ethylene glycol. Using the metal exchange reaction of halogen-substituted magnesium complexes with copper(II) and manganese(II) chlorides in dimethylformamide, the corresponding Cu(II) and Mn(III)octaphenyltetraazaporphyrins were synthesized. Structure of the obtained compounds were identified by UV-Vis, IR, 1H NMR spectroscopy and mass spectrometry methods. The photochemical stability of the synthesized complexes was studied.
Synthesis and antimicrobial activity of hexahydrochromeno[4,3-d]pyrimidine-2-thiones thiouronium salts
Authors: Makarova E. S , Romanycheva A. A , Blyumina M. V , Shetnev A. A , Filimonov S. I
Published: April 2024

The thiouronium salts of chromeno[4,3- d ]pyrimidine-2-thiones were isolated as individual diastereomers and characterized by 1H, 13C NMR spectroscopy and mass spectrometry. Antibacterial and antifungal activity against sensitive strains of gram-negative bacteria E. coli and P. fluorescens , gram-positive bacteria S. aureus and fungi C. albicans was studied.
New bis-(N,N-diethylamino)(phenethyl)methylsilane and 1,2-bis-(N,N-diethylamino)-1,2-di(phenethyl)1,2-dimethyldisilane
Authors: Khoroshavina Yu. V. , Alekseeva V. A , Osetrova L. V
Published: April 2024

New bis-( N , N -diethylamino)(phenethyl)methylsilane and 1,2-bis-( N , N -diethylamino)-1,2-di(phenethyl)-1,2-dimethyldisilane were synthesized by reacting (phenethyl)methyldichlorosilane with diethylamine. Structure of the obtained compounds was confirmed by 1Н, 13С, and 29Si NMR spectroscopy data.
Synthesis and extraction properties of tripodal tetraphosphoryl ligands on the triphenylphosphine oxide platform
Authors: Baulina T. V , Kudryavtsev I. Yu. , Pasechnik M. P , Matveeva A. G , Matveev S. V , Vologzhanina A. V , Turanov A. N , Karandashev V. K , Brel V. K
Published: April 2024

New tetraphosphoryl tripodal ligands on the triphenylphosphine oxide platform [2-Ph2P(O)(CH2) n OC6H4]3PO with different linker length ( n = 3, 4) were synthesized. Composition and structure were found by elemental analysis, IR, multinuclear (1H, 13C, 31P) NMR spectroscopy, and X-ray diffraction. Extraction properties of the ligands were studied by the example of recovery of micro amounts of f -block elements from aqueous phase to 1,2-dichloroethane.
Synthesis of silicon dioxide xerogels and their sorption- desorption properties with respect to nicotine and glycols
Authors: Grigoryan S. G , Hakopyan E. H , Hakobyan R. M , Farmazyan Z. M , Atabekyan M. L , Topuzyan V. O
Published: April 2024

Composites based on silicon dioxide xerogels containing glycerol and nicotine were prepared by hydrolysis of tetraethoxysilane by a single-stage synthesis and two-stage sorption method with a single-stage glycerol sorption in relation to the sorbent reaches 3: 1 by weight. The kinetics of release (desorption) of nicotine from an aerosol mixture with glycols has been studied. The synthesized sorbent is promising for use in aerosol generating systems, as well as carriers and delivery systems for biologically active substances and medicines.
Synthesis of new fused 3(4)-substituted 11-furylthieno[3,2-d]pyrimidine derivatives
Authors: Dabaeva V. V. , Baghdasaryan M. R. , Barkhudaryants I. M. , Paronikyan E. G. , Dashyan Sh. Sh.
Published: April 2024

A method was developed for the synthesis of new fused 3-alkyl-substituted derivatives of thieno[3,2- d ]pyrimidin-4(3 H )-ones based on 11-(2-furyl)-8,8-dimethyl-7,10-dihydro-8 H -pyrano[3′′,4′′:5′,6′]pyrido[3′,2′:4,5]-thieno[3,2- d ]pyrimidin-4(3 H )-one via nucleophilic substitution in the pyrimidine ring. A series of fused 4-amino-substituted 11-furylthieno[3,2- d ]pyrimidine derivatives was also synthesized from the corresponding 4-chloro derivative.
Highly efficient one pot electrocatalytic method for transforming alcohols to nitriles
Authors: Shubina E. N , Kashparova V. P , Bukurova V. S , Kataria Ya. V. , Zhukova I. Yu.
Published: April 2024

A one pot electrocatalytic method was developed for the oxidative transformation of alcohols into nitriles in a two-phase aqueous-organic medium: methylene chloride-aqueous sodium bicarbonate solution. Under the proposed conditions, the catalytic system 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl-pyridine base with the participation of ammonium iodide makes it possible to convert a wide range of alcohols into nitriles with good to excellent yields (81-99%) without the use of catalysts based on toxic metals, hazardous reagents and/or oxidizing agents. In the synthesis, ammonium iodide is simultaneously a source of nitrogen and iodine, and also functions as a component of the background electrolyte.
New europium(III) methoxycinnamates complex: synthesis, thermal and luminescence properties
Authors: Kalinovskaya I. V , Zadorozhnaya A. N , Estrin I. A
Published: April 2024

A method was proposed for the preparative synthesis of mixed-ligand Eu(III) compounds with para -methoxycinnamic acid, ligands from the sodium salt of para -methoxycinnamic acid. It was found that europium(III) methoxycinnamate with hexamethylphosphotriamide has the highest luminescence intensity. Luminescent polymer materials with synthesized europium(III) methoxycinnamates were obtained.
Synthesis of substituted cyclohexenones by reaction of chalcones with acetoacetic acid amides
Authors: Nosova N. V. , Sokolov A. A. , Gein V. L. , Dmitriev M. V. , Mokrushin I. G.
Published: April 2024

New 4-aryl-2-oxo-6-phenyl-3-cyclohexene-1-carboxamides were obtained by the reaction of N -substituted acetoacetic acid amides with benzalacetophenone and 4-methoxybenzalacetophenone in alcohol in the presence of potassium hydroxide. Structure of the prepared compounds was proved using IR, 1H and 13C NMR spectroscopy, mass spectrometry and X-rays analysis data.
Some features of trichlorobiphenyls photolysis
Authors: Gorbunova T. I. , Pervova M. G. , Zakharova G. S. , Podval'naya N. V. , Enyashin A. N. , Saloutin V. I. , Chupakhin O. N.
Published: April 2024

The photolytic decomposition of the Trikhlorbifenil mixture, 2,4,5- and 2,4,6-trichlorobiphenyls under an influence of ultraviolet radiation in presence of tungsten oxide as a catalyst in a methanol medium was studied. A higher rate of photolysis of individual congeners of polychlorbiphenyls was established compared to the congeners of the Trikhlorbifenil mixture. The influence of structural features of polychlorarenes on a depth of photodecomposition and a routes of formation of photodestruction products was considered.
Membrane transport of polyfunctional alkyl (N-alkyl-N,N-dioctylammoniomethyl)phosphonates
Authors: Davletshina N. V. , Ermakova E. A. , Khabibullina A. R. , Dolgova D. R. , Gimadiev T. R. , Davletshin R. R. , Stoykov I. I. , Cherkasov R. A.
Published: April 2024

The membrane transport properties of phosphorylated betaines in relation to mono- and polyfunctional carboxylic acids were studied. The structure of transferred H-complexes was discussed; using IR spectroscopy, the main coordination centers of carriers were revealed. Using the method of quantum chemical calculations, the relationship between the amount of substrate flux, their lipophilicity and the structure of the resulting H-complexes was shown.
Counterexamples to the Assumption on the Possibility of Prolongation of Truncated Solutions of a Truncated LODE
Authors: Abramov S. A. , Ryabenko A. A. , Khmelnov D. E.
Published: April 2024

Previously, the authors proposed algorithms making it possible to find exponential-logarithmic solutions of linear ordinary differential equations with coefficients in the form of power series in which only the initial terms are known. The solution includes a finite number of power series, and the maximum possible number of their terms is calculated. Now, these algorithms are supplemented with the option to confirm the impossibility of obtaining a larger number of terms in the series without using additional information about the given equation a counterexample is constructed to the assumption that it is possible to obtain uniquely defined additional terms. In previous papers, the authors proposed such confirmations for the cases of Laurent and regular solutions.
Convergence of Formal Solutions to the Second Member of the Fourth Painlevé Hierarchy in a Neighborhood of Zero
Authors: Anoshin V. I. , Beketova A. D. , Parusnikova A. V. , Prokopenko E. D.
Published: April 2024

The second member of the fourth Painlevé hierarchy is considered. Convergence of certain power asymptotic expansions in a neighborhood of zero is proved. New families of power asymptotic expansions are found. Computations are carried out using a computer algebra system. Reference to a code that can be used for computing the Gevrey order of the formal expansion of the solution to the second-order differential equation in a symbolic computation packet is given.
Research into the Dynamics of a System of Two Connected Bodies Moving in the Plane of a Circular Orbit by Applying Computer Algebra Methods
Authors: Gutnik S. A. , Sarychev V. A.
Published: April 2024

Computer algebra methods are used to determine the equilibrium orientations of a system of two bodies connected by a spherical hinge that moves in a central Newtonian force field on a circular orbit under the action of gravitational torque. Primary attention is given to the study of equilibrium orientations of the two-body system in the plane of the circular orbit. By applying symbolic differentiation, differential equations of motion are derived in the form of Lagrange equations of the second kind. A method is proposed for transforming the system of trigonometric equations determining the equilibria into a system of algebraic equations, which in turn are reduced by calculating the resultant to a single algebraic equation of degree 12 in one unknown. The roots of the resulting algebraic equation determine the equilibrium orientations of the two-body system in the circular orbit plane. By applying symbolic factorization, the algebraic equation is decomposed into three polynomial factors, each specifying a certain class of equilibrium configurations. The domains with an identical number of equilibrium positions are classified using algebraic methods for constructing a discriminant hypersurface. The equations for the discriminant hypersurface determining the boundaries of domains with an identical number of equilibrium positions in the parameter space of the problem are obtained via symbolic computations of the determinant of the resultant matrix. By numerical analysis of the real roots of the resulting algebraic equations, the number of equilibrium positions of the two-body system is determined depending on the parameters.
Study of Secular Perturbations in the Restricted Three-Body Problem of Variable Masses Using Computer Algebra
Authors: Ibraimova A. T. , Minglibayev M. Dzh. , Prokopenya A. N.
Published: April 2024

A nonstationary restricted three-body problem for variable masses is considered taking into account the reactive forces arising due to anisotropic variation of masses of the bodies. It is assumed that the bodies are spherically symmetric and interact in accordance with Newton’s law of gravitation. On the basis of the equations of motion of the bodies in the relative system of coordinates, differential equations of aperiodic motion along quasi-conic sections in terms of osculating elements are derived. Equations determining the secular perturbations of the orbital elements are derived in the case of small eccentricities and inclinations of orbits. All symbolic computations are performed using Wolfram Mathematica.
Geometric Algebra and Quaternion Techniques in Computer Algebra Systems for Describing Rotations in Eucledean Space
Authors: Velieva T. R. , Gevorkyan M. N. , Demidova A. V. , Korol’kova A. V. , Kulyabov D. S.
Published: April 2024

Tensor formalism (and its special case—vector formalism) is a mathematical technique that is widely used in physical and engineering problems. Even though this formalism is fairy universal and suitable for describing many spaces, the application of other special mathematical techniques is sometimes required. For example, the problem of rotation in a 3D space is not very well described in tensor representation, and it is reasonable to use the formalism of Clifford algebra, in particular, quaternions and geometric algebra representations for its solution. In this paper, computer algebra is used to demonstrate the solution of the problem of rotation in a 3D space using both the quaternion and geometric algebra formalisms. It is shown that although these formalisms are fundamentally similar, the latter one seems to be clearer both for computations and interpretation of results.
Reynolds Analogy Coefficient in the Longitudinal Cylindrical Couette Problem: from the Continuous Medium to Free Molecular Flow
Authors: Abramov A. A. , Aleksandrov V. Yu. , Butkovskii A. V.
Published: April 2024

The gas Couette flow for a cylindrical geometry of bounding surfaces that move in the longitudinal direction relative to their symmetry axis is considered. For a monoatomic gas, the relation between the shear stress and the energy flux transferred to the longitudinal-flow surface (Reynolds analogy) is studied. In the case of continuous medium and free molecular flow regimes, simple explicit analytical expressions for the Reynolds analogy coefficient are obtained, which depend only on the Eckert number and are independent of the ratio of the cylinder radii. The transitional regime for various values of the Knudsen number is studied using the direct simulation Monte Carlo (DSMC) method. It is shown that, in this case, the Reynolds analogy coefficient at a fixed ratio of the radii and the Knudsen number depends on the relative velocity and temperatures of the surfaces mainly through the Eckert number. A relationship between the linear energy fluxes transferred to the cylindrical surfaces is found.
Solution of the Boltzmann Equation in the Continuum Flow Regime
Authors: Tcheremissine F. G.
Published: April 2024

A method for solving the Boltzmann equation is presented that makes it possible to calculate gas flows in the continuum flow regime described by the Navier–Stokes equations. Progress into the region of continuum flows was achieved by applying the conservative projection method for calculating the Boltzmann collision integral, which preserves the leading term of the Enskog–Chapman asymptotics. Optimization of this method that made it possible to considerably decrease the amount of computations is described. Examples of the longitudinal subsonic flow around a flat plate for the case of the Knudsen numbers Kn = (0,01 0,001 0,0001) are discussed.
Improved Quadrature Formula for a Single-Layer Potential
Authors: Krutitskii P. A. , Reznichenko I. O.
Published: April 2024

An improved quadrature formula is derived for a single-layer potential with a smooth density given on a closed or open surface. The formula ensures a uniform approximation of the potential near the surface and preserves the continuity of the potential as the observation point tends to the surface from inside the domain. These properties are confirmed by numerical tests. For the potential computed near the surface, the present quadrature formula yields higher accuracy than previously known quadrature rules, which is also confirmed by numerical tests. Additionally, a quadrature formula for the direct value of the single-layer potential on the surface is derived. Numerical tests conducted with this formula confirm its efficiency and accuracy.
On Stability of an Approximate Solution of the Cauchy Problem for Some First-Order Integrodifferential Equations
Authors: Vabishchevich P. N.
Published: April 2024

The Cauchy problem for a first-order evolutionary equation with memory with the time derivative of the Volterra integral term and difference kernel in the finite-dimensional Banach space is considered. The fundamental difficulties of the approximate solution of such problems are caused by nonlocality with respect to time when the solution at the current time depends on the entire history. Transformation of the first-order integrodifferential equation to a system of evolutionary local equations with the approximation of the difference kernel by a sum of exponential functions is used. For the weakly coupled system of local equations with additional ordinary differential equations, estimates of stability of solution with respect to initial data and right-hand side are obtained using the concept of logarithmic norm. Similar estimates are obtained for the approximate solution using two-level time approximations.
Review of the Theory of Stable Matchings and Contract Systems
Authors: Danilov V. I.
Published: April 2024

A review of works devoted to the theory of stable matchings or, more generally, of stable networks of contracts is given. A set (network) of contracts is called stable if no coalition has an available contract that gives all coalition members strictly more than the proposed set. In a special case, this concept was introduced in 1962 by Gale and Shapley and has since gone a long way in its development both theoretically (theorems, structures, and algorithms) and in the field of applications in economics, physics, biology, and mathematics.
“Fast” Solution of the Three-Dimensional Inverse Problem of Quasi-Static Elastography with the Help of the Small Parameter Method
Authors: Leonov A. S. , Nefedov N. N. , Sharov A. N. , Yagola A. G.
Published: April 2024

We consider direct and inverse problems of three-dimensional quasi-static elastography underlying a cancer diagnosis method. They are based on a model of a tissue exposed to surface compression with deformations obeying linear elasticity laws. The arising three-dimensional displacements of the tissue are described by a boundary value problem for partial differential equations with coefficients determined by a variable Young’s modulus and a constant Poisson ratio. The problem contains a small parameter, so it can be solved using the theory of regular perturbations of partial differential equations. This is the direct problem. The inverse problem is to find the Young modulus distribution from given tissue displacements. A significant increase in Young’s modulus within a certain tissue domain suggests possible malignancy. Under certain assumptions, simple formulas for solving both direct and inverse problems of three-dimensional quasi-static elastography are derived. Three-dimensional inverse test problems are solved numerically with the help of the proposed formulas. The resulting approximate solutions agree fairly well with the exact model solutions. The computations based on the formulas require only several tens of milliseconds on a moderate-performance personal computer for sufficiently fine grids, so the proposed small-parameter approach can be used in real-time cancer diagnosis.
Blow-up of Solutions and Local Solvability of an Abstract Cauchy Problem of Second Order with a Noncoercive Source
Authors: Artem’eva M. V. , Korpusov M. O.
Published: April 2024

An abstract Cauchy problem for a second-order differential equation with nonlinear operator coefficients is considered. The local solvability of the problem in suitable spaces of abstract continuous and differentiable functions is proved. Sufficient conditions for finite-time blow-up of its solutions are obtained.
Uniqueness of Solutions to Initial-Boundary Value Problems for Parabolic Systems with Dini-Continuous Coefficients in a Semibounded Domain on the Plane
Authors: Baderko E. A. , Sakharov S. I.
Published: April 2024

The first and second initial-boundary value problems for second-order parabolic systems with coefficients satisfying the Dini condition in a semibounded plane domain with a nonsmooth lateral boundary admitting cusps are considered. Theorems on the uniqueness of classical solutions of these problems in the class of functions that are continuous and bounded together with their first spatial derivatives in the closure of this domain are proved.
Data Assimilation for the Two-Dimensional Ambipolar Diffusion Equation in Earth’s Ionosphere Model
Authors: Dymnikov V. P. , Kulyamin D. V. , Ostanin P. A. , Shutyaev V. P.
Published: April 2024

The problem of variational data assimilation for the INM RAS two-dimensional diffusion model of the Earth’s ionosphere F region is considered. Total integral electron contents along given paths are used as observation data. The general statement of the problem in differential form is formulated, and its solvability is analyzed. Based on a regularized statement, an iterative algorithm for solving the assimilation problem is constructed, and its convergence is demonstrated. A finite-dimensional approximation is constructed, the numerical solution of the problem is implemented, and the stability and convergence of the difference scheme are proved. The quality of the reconstruction of electron concentration fields is examined in test numerical experiments. It is shown that a weakly perturbed solution is reconstructed with acceptable accuracy for both stationary and evolutionary statements in the case of vertical and slant integration paths.