bluuebunny/crossref_metadata_2025 huggingface dataset:
Badrakemin and Ostol in the Roots of Ferula persica (Apiaceae) Growing in Azerbaijan
Authors: Kerimli E. G. , Ibadullayeva S. J. , Aleskerova A. N.
Published: April 2024

Abstract—New localities of Ferula persica Wild. (Apiaceae) populations in the Gobustan, Siazan and Absheron regions of the Azerbaijan were found. The coumarin compounds osthole and badrakemin were isolated and identified from the resin of F. persica roots. Badrakemin was obtained from the studied raw materials for the first time.
In Vitro Introduction of Lespedeza davurica (Fabaceae)
Authors: Lonchakova T. E. , Pianova A. S. , Berdasova K. S.
Published: April 2024

Abstract—Rare species Lespedeza davurica (Laxm.) Schindl. (Fabaceae), growing in the Russian Federation, was for the first time introduced into in vitro culture. Efficient sterilization protocol was selected: seeds were soaked in sulfuric acid for 25 min, then washed in distilled water 5 times for 30 s, then soaked in 1% silver nitrate solution for 25 min, then in 1% sodium chloride solution for 15 min, and washed in distilled water 3 times for 30 s. The overall seed germination was sufficiently high – 78.8%. It was observed, that cotyledon leaves in most plants appeared by the end of the first week of cultivation, true leaves – by the end of the second week, additional shoots began to form within the first month of cultivation. The resulting culture was propagated under in vitro conditions using additional shoots. The effect of thidiazuron at concentrations of 0.5 and 0.1 mL/L was traced. It was shown that Murashige and Skoog medium without growth regulators are suitable for cultivation and micropropagation of the species under study, and when the medium is supplemented with thidiazuron it can be used to obtain more plant material. The results of our study are of interest for the fundamental and applied aspects of the study of L. davurica.
Preparations from Sorbus aucuparia (Rosaceae) in Experimental Therapy of Malignant Neoplasms: Emerging Opportunities
Authors: Rybalkina O. Yu. , Razina T. G. , Zueva E. P. , Amosova E. N. , Kalinkina G. I. , Minakova M. Yu. , Zhdanov V. V.
Published: April 2024

Abstract—The review presents information from the literature and our own data on some pharmacological properties of Sorbus aucuparia L. Particular attention is paid to the research in experimental oncology.
Chemical Composition and Therapeutic Effects of Some Astragalus (Fabaceae) Species
Authors: Klichkhanov N. K. , Suleimanova M. N.
Published: April 2024

Abstract—The review integrates information on the studies of component composition and biological activity of some Astragalus L. (Fabaceae) species published over the last 5–7 years. The aerial and underground parts of 34 Astragalus species contain triterpene saponins, flavonoids, polisaccharides, tannins, free organic acids, higher fatty acids, vitamins, trace elements, and other constituents. Among Astragalus species, the best studied in relation to component composition and biological activity is A. membranaceus (Fisch.) Bunge. In vitro and in vivo experimental studies suggest that total amount of bioactive substances, fractions of and individual compounds extracted from different parsts of A. membranaceus and A. membranaceus var. mongholicus exhibit anti-inflammatory, immunomodulatory, antioxidant, anticancer, cardiportactive, and hepathoprotective activity. The composition and biological effects of other Astragalus species have been little studied. The review synthesizes recent advances in the studies of new compounds extracted from Astragalus species, and on their biological activity.
Changes in the Shoot Apical Meristem with Decrease in Illumination within the Crown of Pseudotsuga menziesii (Pinaceae) Introduced in St. Petersburg
Authors: Skupchenko V. B.
Published: April 2024

Abstract—In Pseudotsuga menziesii Mirb. Franco introduced in St. Petersburg, the changes in the apical meristem morphogenesis during the formation of a short bud shoot with covering scales and meristematic primordium of shoot with needles, under the decrease in illumination within the crown were studied. Terminal 1–4-year-old shoots of the third-order branches in the lower part of the crown with a relative light availability (RLA) in the range of 23.9–18.3% perform full annual cycle of morphogenesis of the shoot apical meristem. Before each stage of morphogenesis, the apical meristem performs independent volume growth associated with the formation of mother groups of phytomer cells of covering scales and needles in the peripheral meristem. With RLA reducing to 15.1–15.4%, in terminal 5–6-year-old shoots over the growing season, the apical meristem performs only formation of a short bud shoot with covering scales and stops volume growth. This is because in the vascular bundles of the stele of the short bud stem, the sieve cells of the phloem are not formed, and the xylem part is poorly developed. The direct contact of the apex with the stele of the bud stem is blocked by procambium bundles, since their cells are differentiated and crystalline cellulose is accumulated in the cell walls. The cell walls of the bark parenchyma of the short bud stem contains significantly less birefringent inclusions, and only single small resin receptacles.
Effect of Sodium Additives on the Kinetics of the Solid-State Oxidation of Lead Babbitt PbSb15Sn10Na
Authors: Ganiev I. N. , Khodzhaev Kh. M. , Khodzhaev F. K.
Published: April 2024

A study is performed of the kinetics of oxidation of lead babbitt with 1.0 wt % of sodium in the 373–473 K range of temperatures. The kinetic and energy parameters of the oxidation of the alloys are determined. It is found that the weight gain of the alloys grows rapidly during the first 15–20 min of oxidation and then acquires an almost constant value. Oxide films that form at the beginning of oxidation have no protective properties, as is confirmed by an increase in the alloys’ rate of oxidation along with temperature in the initial period. It is revealed that sodium dopant additives taken in concentrations of 0.01–1.0 wt % enhance the oxidizability of the original alloy and considerably refine its microstructure. X-ray diffraction analysis shows that the alloys’ products of oxidation consist of oxides (Pb3Sb2O8.47)6.4, PbO, Pb3O4, Pb0.828O2, Sb2O4, Na3SbO3, NaSbO3, and PbSb2O6.
Potentiometric Study of Complexation in a Copper(II)–1-Phenyl-2,3-dimethylpyrazoline-5-thione–Hydrochloric Acid–Acetone System
Authors: Khasanov F. N. , Bakhodurov Yu. F. , Goziev E. J. , Rakhmatulloev B. K.
Published: April 2024

Potentiometry is used to study the formation of Cu(II)–1-phenyl-2,3-dimethylpyrazoline-5-thione (1-P-2,3-DMP-5-T) complex in a mixed solvent. The compositions of the complexes are determined, and their stepwise constants of stability are calculated. It is shown that when Cu(II) reacts with 1-P-2,3-DMP-5-T in a medium of mixed solvent HCl + acetone (10 : 1), quantities ΔH, ΔG, and ΔS have negative values at all stages.
Selective Hydrogenation of Pyridine and Derivatives of It on Bimetallic Catalysts Modified with Chitosan
Authors: Kustov A. L. , Dunaev S. F. , Finashina E. D.
Published: April 2024

A study is performed of the catalytic properties of bimetallic nanoparticles based on palladium and a base metal (silver or copper) supported on alumina modified with chitosan in the selective hydrogenation of pyridine and derivatives of it with the formation of piperidine and derivatives of it. It is shown that the effect of increasing the activity of bimetallic nanoparticles is due to the small size of particles (2–3 nm), compared to the monometallic palladium catalyst. It is established that the conversion of pyridine reaches 99% with 99% selectivity toward piperidine under mild conditions (60°C; H2 pressure, 70 atm).
Mathematical Processing of Experimental Data Obtained with Ampoule and Titration Calorimeters Equipped with Different Types of Cells
Authors: Meshkov A. N. , Gamov G. A.
Published: April 2024

An algorithm is described for calculating the equilibrium constants and changes in the enthalpy of chemical reactions according to data from a calorimetric experiment performed on instruments of different types. Freeware is developed that executes the described algorithm. Differences from existing computer programs with similar functionality are briefly discussed, along with different statistical criteria of maximum likelihood.
Xanthine and Methyl Xanthine Molecules in Reactions with Low-Energy Electrons
Authors: Muftakhov M. V. , Tuktarov R. F.
Published: April 2024

Intense signals of [M–H]– ions have been detected in the low-energy region of the resonance electron capture mass spectra of xanthine and its methyl derivatives. It was assumed that xanthine molecules can act as radioprotectors in living cells. It was concluded that the discovered release of the carbonyl and methyl groups is associated with xanthine metabolism reactions in the tissues of living organisms.
Relationships of Enantioselective Retention of Chiral Oxazolopyrroloquinolones on a Stationary Phase with Grafted Ristocetin А Antibiotic from Aqueous Methanol Solutions
Authors: Stepanova M. V. , Asnin L. D. , Boteva A. A.
Published: April 2024

The mechanisms of retention and separation of the enantiomers of chiral oxazolopyrroloquinolones on a stationary phase with graftеd macrocyclic antibiotic ristocetin A under conditions of high-performance liquid chromatography with aqueous methanol mobile phases have been studied. The retention factor was found to decrease monotonically when the CH3OH concentration in the mobile phase increased to 90 vol %; then it slightly increased as the composition of the mobile phase approached pure methanol. The thermodynamics of adsorption of oxazolopyrroloquinolones in different regions of this dependence was studied. A mathematical model has been proposed; it describes well the experimental data and allows for analyte solvation in the mobile phase and competitive adsorption (with mobile phase components) on a chiral selector. The results were compared with previously obtained data for water–acetonitrile mobile phases. The reasons for the observed differences were discussed.
Organic Inhibitors of Metal Corrosion in Acid Solutions. I. Mechanism of Protective Action
Authors: Avdeev Ya. G. , Kuznetsov Yu. I.
Published: April 2024

The review summarizes and analyzes the current state of research in the field of corrosion of metals in acid solutions and their inhibitory protection. The most important concepts about the metal corrosion mechanism in acidic media were considered. The existing experimental approaches to the study of metal corrosion in acid solutions and the effect of organic corrosion inhibitors on this process were discussed. It was shown that electrochemical and physicochemical methods play an important role in studies of the state of the metal surface. The mechanisms of metal corrosion inhibition in acid media were analyzed. The thermodynamic and kinetic aspects of adsorption of inhibitors on metals were considered. The maximum efficiency in metal protection is shown by organic compounds whose molecules are capable of chemisorption interaction with the metal surface, forming polymolecular protective layers of molecules chemically bonded with one another.
Self-Assembly Polymersomes Based on Sulfite Lignins with Biological Activity
Authors: Lugovitskaya T. N. , Ulitko M. V. , Kozlova N. S. , Rogozhnikov D. A. , Mamyachenkov S. V.
Published: April 2024

A relatively simple way of obtaining polymer vesicles via self-assembly in an aqueous acetone medium is proposed on the basis of biologically active polymer sulfite lignin (lignosulfonate). The size and morphology of polymersomes are controlled according to molecular weight (46.300–60.000 Da), the concentration of lignosulfonate (CLS 0.10–1.28 g/dm3), and the content of acetone (φAc 0.6–4.0 vol %) in the suspension. The resulting polymersomes are characterized by sizes of 200–350 nm, a polydispersity index of 0.25–0.18, and a ζ potential of −26.3 to −51.0 ± 2.2 mV. Air-dried powders of polymersomes isolated from the corresponding suspensions are polydisperse, with sizes ranging from 40 to 300 nm. The morphology of polymersomes is confirmed by electron microscopy data (SEM, TEM, and AFM). In light of the biological activity of lignosulfonate, polymersomes derived from it can potentially be used in such biomedical applications as targeted drug and gene delivery, enzymatic catalysis, and optical imaging in vivo.
Effect of Temperature on the Thermodynamics of the Stepwise Dissociation of Alanyl-Phenylalanine in Aqueous Solutions
Authors: Lytkin A. I. , Chernikov V. V. , Krutova O. N. , Krutov P. D. , Romanov R. A.
Published: April 2024

The heats of interaction between alanyl-phenylalanine and solutions of nitric acid and potassium hydroxide at 288.15 and 308.15 K and solution ionic strengths of 0.5, 0.75, and 1.0 are determined via calorimetry with KNO3. Standard thermodynamic characteristics (ΔrH°, ΔrG°, ΔrS°, ΔC∘pΔ∘) of the reactions of acid–base interaction in aqueous solutions of alanyl-phenylalanine. The effect temperature has on the heats of dissociation of alanyl-phenylalanine is considered along with the relationship between the thermodynamic characteristics of the dissociation of the dipeptide and the structure of this compound.
Nature of the Increase in the Rate of Combustion of a Ti–C Mixture Diluted with an Inert Additive
Authors: Seplyarskii B. S. , Kochetkov R. A. , Lisina T. G. , Abzalov N. I.
Published: April 2024

An original comparative study is performed of the combustion of granular and powder Ti–C and (Ti–C)+20%Ni mixtures with granules of different sizes, while varying titanium particle sizes in a range of 31–142 mm. It is found that the rate of combustion of the (Ti–C)+20%Ni powder mixture is 2–3 times higher than that of a Ti–C mixture, despite the lower temperature of combustion of the former. The results are interpreted in terms of the convective–conductive combustion model and attributed to the inhibitory effect of impurity gases that evolve while heating the component particles ahead of the combustion front. The rate of combustion of the granules’ material is calculated using those of granular mixtures with granule sizes of 0.6–1.7 mm. This rate can be thought of as the rate of combustion of a powder mixture in which the effect of impurity gases is neutralized. It is proposed that the ratio of the rates of combustion of the material inside the granules and the powder mixtures be used as a quantitative measure of the effect impurity gas evolution has on the combustion of powder mixtures.
Analysis of the Conditions of Mechanical Equilibrium on the Curved Surface of a Vapor–Liquid System in a Gravitational Field
Authors: Tovbin Yu. K.
Published: April 2024

A thermodynamic analysis of mechanical equilibrium conditions is performed for the curved interface of a vapor–liquid system in the gravitational field potential with regard to ratios of experimental times of relaxation of thermodynamic parameters (momentum, energy, and mass). In a kinetic analysis of the relaxation stage of reaching the equilibrium state, it is revealed that it is important to consider the physical nature of the boundary of separating phases. The mechanical model of the boundary is one with an intermediate foreign film preventing the attainment of chemical equilibrium between the neighboring phases. The real boundary of coexisting phases has a variable density profile corresponding to the condition of the constant chemical potential throughout the region of transition and in the neighboring coexisting phases. The absence of an intermediate film excludes the priority of the mechanical equilibrium over the chemical equilibrium and results in pressure being the function of local temperature and chemical potential values (excluding the application of the Laplace equation). Considering times of relaxation is found to change the familiar Gibbs expression for the pressure jump between coexisting vapor and fluid as functions of the boundary in the gravitational field potential. A consequence of considering the correct ratio of momentum and mass times of relaxation is discussed: the phase equilibrium conditions of a separating vapor–liquid system in combined gravitational and surface force fields must be analyzed in order to solve problems of the capillary theory.
Thermochemical Analysis of the Interaction between Pyridoxine and L-Carnosine, L-Histidine, and L-Asparagine in Aqueous Solutions
Authors: Tyunina E. Yu. , Krutova O. N. , Barannikov V. P.
Published: April 2024

Calorimetry is used to study the interaction between dipeptide L-carnosine (Car) and amino acids L-histidine (His) and L-asparagine (Asn) with pyridoxine (PN) in an aqueous solution. Experimental values of the enthalpy of dissolution of amino acids and peptide in an aqueous PN solution at T = 298.15 K are obtained for the first time. The thermodynamic characteristics and stoichiometry of the formation of molecular complexes between the reactants are determined. It is found that the stability of the resulting complexes depends on the structure of the reactants and falls in the order Car Asn His. It is shown that the main contribution to the stabilization of the resulting complexes comes from the entropy component of the Gibbs energy of complexation.
Low-Temperature Synthesis of Metal–Organic Coordination Polymers Based on Oxo-centered Iron Complexes: Magnetic and Adsorption Properties
Authors: Baimuratova R. K. , Zhinzhilo V. A. , Uflyand I. E. , Dmitriev A. I. , Zhidkov M. V. , Ovanesyan N. S. , Kugabaeva G. D. , Dzhardimalieva G. I.
Published: April 2024

A low-temperature approach is described for preparing mesoporous metal–organic frameworks using nontoxic solvents and pre-synthesized polynuclear iron complexes as secondary building units. The obtained compounds are characterized via IR and Mössbauer spectroscopy, X-ray powder diffraction analysis, thermogravimetric analysis, and differential scanning calorimetry. The specific surface of the obtained compounds and their adsorption capacity for organic dyes methylene blue and Congo red are determined. Particular attention is given to dependences M(T) and M(H) of the magnetic moment of the obtained samples on temperature and strength of the magnetic field, respectively. The dyes’ adsorption characteristics and efficiency of sorption are determined by varying such factors as period of contact, amount of adsorbent, and temperature. The removal of dye at a concentration above 90% is observed as early as 20–30 min after the beginning of adsorption. Langmuir and Freundlich isotherms are used to describe the experimental data. It is shown that the process of adsorption at the initial concentration of the dye is described most accurately by the Langmuir adsorption isotherm. The rate constants of adsorption are calculated using pseudo-second order kinetic equations.
Calculating Vertical Ionization Energies of Hydrated Biological Chromophores Based on Multiconfigurational Perturbation Theory
Authors: Boichenko A. N. , Bochenkova A. V.
Published: April 2024

Here we introduce a methodology for calculating vertical detachment energies (VDE) and vertical ionization energies (VIE) of anionic and neutral chromophores in aqueous environment. The proposed method is based on the extended multiconfigurational quasidegenerate perturbation theory coupled to the explicit treatment of solvent effects in the frame of the effective fragment potential method. We show that the solvent polarization contribution must be considered for getting accurate quantitative estimations of VDEs and VIEs. The calculated values of VDE for phenolate (7.3 eV) and VIE for phenol (7.9 eV) in aqueous environment are in good agreement with the experimental results obtained using X-ray and multiphoton UV photoelectron spectroscopy. Our approach will be useful for studying processes of photoinduced electron transfer from anionic as well as neutral biological chromophores in aqueous solution.
Heat Capacity and Thermodynamic Functions of Sodium-Alloyed Lead Babbitt BNa (PbSb15Sn10Na)
Authors: Ganiev I. N. , Khodzhanazarov Kh. M. , Khodzhaev F. K. , Eshov B. B.
Published: April 2024

The heat capacity of sodium-alloyed lead babbitt BNa (PbSb15Sn10Na) is determined experimentally, and the temperature dependences of the changes in the thermodynamic functions of this alloy are calculated. The temperature dependence of the heat capacity of babbitt BNa is studied in the cooling mode using the SigmaPlot 10.0 software. Polynomials are determined for the temperature dependences of the heat capacity and the changes in the thermodynamic functions (enthalpy, entropy, and Gibbs free energy) of babbitt BNa and a reference sample (S00-grade Pb), that describe these dependences with coefficient of correlation Rcorr = 0.999. It is shown that the heat capacity of babbitt BNa grows along with the content of sodium, its enthalpy and entropy grow along with temperature and the content of sodium, and its Gibbs energy falls.
Calculating Coefficients of the Gas Hydrate Distribution of CO2 and H2S when Removing Them from a Methane-Containing Gas Mixture
Authors: Kudryavtseva M. S. , Petukhov A. N. , Shablykin D. N. , Stepanova E. A. , Vorotyntsev V. M.
Published: April 2024

A study is performed of the effect process temperature and pressure have on the distribution of CO2 and H2S gas hydrate in a model methane-containing gas mixture of CH4 (89.00 mol %)–CO2 (5.00 mol %)–n-C4H10 (3.00 mol %)–N2 (2.00 mol %)–H2S (1.00 mol %) containing components of natural gas. Modeling is done at low (4.00 MPa) and high (8.00 MPa) pressures in the 272.15–278.15 K range of temperatures. The temperature dependences of the coefficients of the gas hydrate distribution of natural gas components are shown to differ. The maximum coefficients of the gas hydrate distribution of CO2 and H2S are 1.24 and 31.83, respectively, at a process temperature of 272.15 K and a pressure of 8.00 MPa. It is found that n-C4H10 in natural gas lowers the coefficient of the gas hydrate distribution of CO2. It is concluded that natural gas deposits with low contents of n-C4H10 must be used to effectively concentrate CO2 in the gas hydrate phase.
Thermodynamics of the Formation of Intermediate Complexes in the Oxidation of Citric Acid with Cerium(IV) and the Kinetics of Their Intramolecular Redox Decomposition
Authors: Voskresenskaya O. O. , Skorik N. A.
Published: April 2024

The thermodynamic and kinetic characteristics of cerium(IV)–citrate complexes formed at the first step of oxidation of citric acid with cerium(IV) are studied via spectrophotometric, pH-metric, and kinetic means at an ionic strength of I = 2 in the 1–3 range of the pH of a sulfuric acid medium at T = 290.15–303.15 K. The composition of these complexes, the species of the organic ligand in them, the thermodynamic parameters of their formation, and the kinetic parameters of the intracomplex redox decomposition are determined. The most likely scheme of the initial steps of the redox process in the system are considered, and its rate law and the related mechanism of the reaction are established. Results are compared to ones from studies of other cerium(IV) systems with hydroxy and dicarboxylic acids.
Calorimetric Study of Mixtures of Polypropylene with 90 wt % Low-Molecular Organic Compounds after Plastic Deformation at a High Pressure
Authors: Zhorin V. A. , Kiselev M. R.
Published: April 2024

Mixtures of polypropylene (10 wt %) with anthracene, phthalocyanine, indigo, adamantane, congo red, spiropyran, safranin, methyl orange, bromocresol purple, phenolphthalein, fluorescein, phenol red, thymol blue, aspartic acid, cyanuric acid, thymolphthalein, and rhodamine were subjected to plastic deformation at a pressure of 1 GPa on an anvil-type high-pressure apparatus. It was found by DSC that the thermograms of heating of the deformed mixtures in the temperature range below Tm of the polymer contain endothermic peaks of melting of small polymer crystallites with enthalpies reaching 220–240 J/g in some samples, as well as exothermic peaks of cold crystallization with enthalpies reaching 430–470 J/g. The melting was described by bi- and trimodal peaks, whose total enthalpy reached 2200–2400 J/g in some mixtures. The polymer crystallization in the deformed mixtures was described by single exothermic peaks, whose enthalpies differed little from the crystallization enthalpy of the starting polypropylene. An increase in the enthalpies of thermal processes in the deformed mixtures was attributed to the appearance of double electric layers at interfaces between the mixed phases.
Synthesis of Niobium η-Carbide Nb3(Fe,Al)3C by Mechanical Alloying in a Liquid Organic Medium
Authors: Eryomina M. A. , Lomayeva S. F.
Published: April 2024

The η-carbide Nb3(Fe,Al)3C phase was synthesized for the first time by mechanical alloying of Nb, Al, and Fe in petroleum ether followed by annealing. The synthesis of carbide occurs due to carbon accumulated from the grinding medium. If mechanical alloying is performed using steel vials and balls, the composites based on η-carbide can be obtained without additional introduction of iron; contaminant iron is involved in the formation of Nb3(Fe,Al)3C.
Vibrationally Excited Ozone in Kinetics of O/N/Ar Mixtures after Ozone Photolysis
Authors: Mankelevich Yu. A. , Rakhimova T. V, , Voloshin D. G. , Chukalovskii A. A.
Published: April 2024

The developed kinetics of the vibrationally excited states of ozone (with excitation of up to five vibrational quanta), built into the chemical kinetics of O/N/Ar mixtures, was used to model the series of photolysis experiments of V.N. Azyazov et al. The experimental and calculated dynamics of O3 and O2(a1∆) in various O3/O2/Ar mixtures were compared. The dynamics of chemiluminescent radiation of NO∗2NO2∗ in the titration technique and the applicability of this technique to measuring the dynamics of O atoms in an O3/O2/N2O/Ar mixture were considered. The dynamics of various states of O3(v1,v2,v3) after ozone photolysis was analyzed in detail. The role of these states in the acceleration of the chemical conversion of oxygen components and nitrogen oxides, occurring with competition with ozone vibrational relaxation, was considered.
Physicochemical Approaches to the Study of the Antioxidant Activity of Glycyrrhizin
Authors: Polyakov N. E. , Leshina T. V.
Published: April 2024

The review presents an attempt to collect and systematize the available data on the antioxidant activity of glycyrrhizin obtained by various physicochemical methods and to stimulate further discussions on the mechanisms of its activity and prospects for its use as a multifunctional drug delivery system.
Quantum-Chemical Modeling of Ag/CeO2 Nanoscale Catalysts
Authors: Shor E. A. , Shor A. M. , Nasluzov V. A.
Published: April 2024

The authors summarize results from calculations using the density functional theory for atoms and small silver clusters on surfaces of nanostructured cerium(IV) oxide, along with the adsorption and transformations of O2 and CO molecules on these systems. Stoichiometric Ce21O42, which has {100} and {111} nanofacets with adsorption centers containing four and three oxygen atoms, is used to model surfaces of cerium oxide. It is shown the O4-center is a center of the selective adsorption of metal atoms. A silver atom on an O3‑center is less stable but it shows a greater ability to activate an O2 molecule. Results from calculations on the {100} and {111} faces of Ce21O42 nanoparticles are compared to data for infinite CeO2(100) and CeO2(111) surfaces. The efficiency of Ag/Ce21O42 atomic complexes is shown in the oxidation of carbon monoxide.
The Kinetic Parameters of Sequential Topochemical Reactions with Parallel Formation of Gaseous Products
Authors: Borshchevskii A. Ya.
Published: April 2024

Based on the example of solid-phase reactions of fullerenes with fluoride compounds of metals with a variable valence, the most important parameters of the kinetic model developed earlier by the author have been calculated. The model explains the selectivity of these reactions, which made it possible to obtain some C60 fullerene fluorine derivatives in an individual form, and opens ways to control them. For some of the reactions, a comparison was made with the data on the activation energy of elementary stages obtained earlier in the processing of mass spectral experiments. The estimates we made will contribute to the fine control of the conditions for a similar synthesis of other fullerene derivatives with small functional groups. They may also be useful in any long chain sequential reactions that produce broad gaseous or dissolved products.
Physicochemical and Toxicological Studies of the Polymorphic Modifications of the Rodenticidal Substance “Chlorophacinone”
Authors: Kochetov A. N. , Nosikova L. A. , Kudryashova Z. A. , Chernyshev V. V. , Tafeenko V. A. , Tsivadze A. Yu.
Published: April 2024

The results of studies of the polymorphism of the rodenticidal substance 2-[(4-chlorophenyl)phenylacetyl]-1H-indene-1,3(2H)-dione “chlorophacinone”, which has an anticoagulant mechanism of action, are presented. Methods for the synthesis of two new polymorphic forms (III and IV) have been established, for which data from physicochemical studies (IR, XRD) and information on the biological activity (toxicity) of polymorphs are given. Both forms crystallize in the monoclinic crystal system with space group P21/с and the following unit cell parameters: a = 16.698(1) Å, b = 5.632(1) Å, c = 20.253(2) Å, β = 109.65(1)° for III; and a = 9.853(1) Å, b = 9.041(1) Å, c = 20.474(1) Å, β = 97.322(3)° for IV. Polymorphic form IV with a toxicity parameter DL50 (gray rats) of 0.47 mg/kg has the highest biological activity versus 2.74 mg/kg for the less active form III. A method of identification of the most active form (IV) by IR spectroscopy was proposed.
Using a Neural Network to Study the Effect of the Means of Synthesizing Exfoliated Graphite on Its Macropore Structure
Authors: Krautsou A. V. , Shornikova O. N. , Avdeev V. V.
Published: April 2024

Graphite intercalated compounds (GICs) with different stage numbers are prepared chemically from highly oriented pyrolytic graphite (HOPG), natural flaked graphite (FG) and nitric acid. Exfoliated graphite samples (EG-T) are synthesized from GICs via water treatment followed by thermal shock. The aim of this work is to investigate the dependence of the inner EG-T pore structure on the extent of oxidation and type of graphite by processing scanning electron microscopy (SEM) micrographs of EG-T cross sections. A procedure is developed on the basis of a deep convolutional neural network that speeds up image processing with no appreciable loss of accuracy. A strong correlation is found between EG-T pore structure parameters, the depth of oxidation, and the type of graphite.
Synthesis in Nb + 2Si Mixtures Produced in Different Modes of Discrete Mechanical Activation
Authors: Lapshin O. V. , Shkoda O. A. , Bolgaru K. A. , Reger A. A.
Published: April 2024

An experimental study is performed of the two-stage mechanochemical synthesis of niobium silicide. Theoretical estimates are made on the basis of the resulting macrokinetic model. The initial Nb + 2Si mixture is mechanically activated in the first stage, and the NbSi2 product is synthesized in the second. The effect the period of mechanical treatment has on the activated mixture’s morphology, temperature, and rate of burning is studied, along with the phase composition of the final reaction product. Kinetic constants are calculated that describe the dynamics of the two-stage mechanochemical synthesis of niobium silicide.
The Molecular Mechanism of H2O2 Decomposition in a Reaction with an Au25(SCH3)12 Cluster
Authors: Nikitenko N. G. , Shestakov A. F.
Published: April 2024

The reactions of neutral and anionic Au25(SCH3)12 clusters with one H2O2 molecule (mechanism I) and with its dimer (H2O2)2 (mechanism II) have been studied within the framework of the density functional theory (DFT). It has been established that all processes proceed with low activation barriers and a large gain in energy during the formation of products, and also that mechanisms I and II are interconnected. Based on the calculated data, the structure of gold clusters with the most probable active centers for further interaction with methane, which contain one or two O atoms, is proposed. In this case, clusters containing the O2 fragment can form not only in the reaction of the initial cluster Au25(SCH3)12 with hydrogen peroxide, but also with molecular oxygen, since the O2 adsorption energy is low and the process is close to equilibrium.
Structure of the Nearest Environment of Ions in Aqueous Solutions of Cadmium Chloride and Nitrate According to the Data of X-ray Diffraction Analysis
Authors: Smirnov P. R. , Grechin O. V,
Published: April 2024

Quantitative characteristics of the nearest environment of ions in aqueous solutions of cadmium chloride and nitrate are determined by X-ray diffraction analysis in a wide range of concentrations under standard conditions. It is found that, in the studied systems, the coordination number of the cation increases with dilution from 4 to 6. The structure of solutions in the entire studied range of concentrations is determined by ionic associates of the contact type. In solutions of cadmium nitrate, the nitrate ion is monodentately coordinated to the cation.
On the Thermodynamic Stability of Multicomponent Reactive Systems
Authors: Toikka A. M. , Misikov G. Kh. , Toikka M. A.
Published: April 2024

Derivation and analysis of conditions of the thermodynamic stability for multicomponent reactive systems are proposed based on transformations and different representations of the stability matrix. Stability boundaries and spinodal conditions in systems with chemical interaction of compounds are discussed.
A Simple Highly Accurate Algebraic Model of Phase Transitions on Square, Hexagonal, and Triangular Flat Faces
Authors: Votyakov E. V. , Tovbin Yu. K.
Published: April 2024

A simple, highly accurate algebraic model is proposed for describing phase transitions on flat faces of square, hexagonal, and triangular structures. The model is derived using the cluster variational approach within the Ising model and expressed in an analytical form by choosing a basic closed-form cluster of the minimal size for each facet structure with nearest neighbors of z = 3 (triangular), 4 (square), and 6 (hexagonal). The new model provides three times more accurate equations for molecular distributions of particles in the Ising model than earlier analytical expressions. The model’s analytical equations allow direct calculations of molecular distributions. (Only iterative numerical means were used earlier to obtain results of the same accuracy.) The effect of refinements when considering correlation effects in the new model is compared to traditional mean-field and quasi-chemical (QCA) approximations when calculating isotherms and pair and cluster distribution functions. Analytical expressions are obtained for the critical temperature of a segregation-type phase transition.
Solubility in the Ternary Water–Salt System GdCl3–TbCl3–H2O at 25°С
Authors: Charykov N. A. , Gur’eva A. A. , German V. P. , Keskinov V. A. , Rumyantsev A. V. , Semenov K. N. , Kulenova N. A. , Sadenova M. A. , Shushkevich L. V. , Letenko D. G. , Matuzenko M. Yu.
Published: April 2024

The solubility diagram of the ternary system GdCl3–TbCl3–H2O is studied by means of isothermal saturation in ampules at 25°С. A continuous series of solid solutions of isovalent substitution crystallizes in the system GdxTb1−xCl3⋅6H2O.GdTb1−Cl3⋅6H2O. The diagram of solubility in the three-component system GdCl3–TbCl3–H2O at 25°C is calculated according to the classical Pitzer model. Results from experiments agree convincingly with ones from thermodynamic modeling.
Catalysis of the Abramov Reaction under Conditions of Microwave Activation
Authors: Davletshin R. R. , Sedov A. N. , Davletshina N. V. , Ivshin K. A. , Fedonin A. P. , Osogostok A. P. , Cherkasov R. A.
Published: April 2024

Two series of α-hydroxyphosphonate synthesis according to the Abramov reaction are conducted under conditions of microwave activation. Acidic and basic catalysts are used along with 4-bromobenzaldehyde and 3-methoxy-4-hydroxybenzaldehyde. O,O-Diethylphosphite is used as a phosphorylating agent. The conversion of the reaction products is monitored via NMR spectroscopy. The optimum conditions for the synthesis of α-hydroxyphosphonates are selected. The crystal structure of reaction product O,O‑diethyl((4-bromophenyl(hydroxy)methyl)phosphonate 2, which crystallizes in the space group P21/n and is stabilized by multiple C–H⋅⋅⋅O and C–H⋅⋅⋅π interactions, is described for the first time.
Effect of the Nature of the Solvent on the Formation of Ferrocene Cations during the Protonation of Acetil- and 1,1'-Diacetylferrocene with Perchloric Acid and Their Oxidation with Iodine
Authors: Fomin V. M. , Shuklina N. N.
Published: April 2024

It is established that the rate of the formation of ferrocenium cations in reaction mixture acetylferrocene (1,1'-diacetylferrocene) + I2 + HClO4 as a result of the protonation of metal complexes (MCs) and their oxidation with iodine in dioxane and acetonitrile depends on different mechanisms and is described by kinetic equations obtained by analyzing schemes of the process. The observed difference is due to different roles of the protonation of metal complexes and their oxidation with iodine in these solvents.
Photocatalytic Activity of Titania Modified with Vanadium, Zirconium, and Hafnium
Authors: Kostyleva E. I. , Novikov A. N. , Il’ina T. A. , Dedov N. A. , Shchukina I. A.
Published: April 2024

Titania and silica nanoparticles are synthesized via the hydrolytic polycondensation of tetrabutoxytitanium and tetraethoxysilane in an ultrasonic field. The photocatalytic activity of the synthesized materials under exposure to ultraviolet radiation is studied using the example of the photodegradation of the rhodamine G organic dye. A titania–silica mixture is modified with vanadium(V), zirconium(IV), and hafnium(IV) compounds; the modification leads to a shift of the photocatalytic activity to the visible region of the spectrum.
Electrical Conductivity and Ionic Association in Tetraalkylammonium Ionic Liquids in Acetonitrile Solutions
Authors: Zhuravlev O. E. , Lebedev I. I. , Yulmasov G. S.
Published: April 2024

A study is performed of the electrical conductivity (EC) of ionic liquids based on quaternary triethylalkylammonium salts with tetrafluoroborate and hexafluorophosphate anions in acetonitrile. Conductometric data on these compounds are analyzed. Constants Ka of the ionic association of the limiting molar electrical conductivity (λ0) and the standard Gibbs energy of association (ΔG0) in solutions are calculated using the Lee–Wheaton formula. The Stokes radii, limiting mobility, and limiting coefficients of diffusion are found for tetraalkylammonium cations.
Mixed Network of Hydrogen Bonds in Aqueous Solutions of 3-Amino-1-propanol: Results of Molecular Dynamic Modeling
Authors: Balabaev N. K. , Agayan G. M. , Rodnikova M. N. , Solonina I. A. , Razumova A. B.
Published: April 2024

The H2O–3-amino-1-propanol (3AP) system at 300 K was studied by molecular dynamics, graph theory, and Delaunay simplex methods. All the molecules were shown to be bound into a three-dimensional network of hydrogen bonds over the entire range of concentrations in the system. The characteristics of the networks and their concentration dependences were determined. The frequency at which the environment of molecules changes is discussed. The results were compared with those for mixed networks in aqueous solutions of 1,3-propanediol and monoethanolamine.
Electrocatalytic Reduction of CO2 when Using N-Substituted Salts of 2,4,6-Triphenylpyridine
Authors: Knyazev A. V. , Dolganov A. V. , Klimaeva L. A. , Kostryukov S. G. , Kozlov A. Sh. , Yudina A. D. , Tarasova O. V.
Published: April 2024

A study is performed of the electrocatalytic activity of substituted pyridine salts (N-hydro-, N‑methyl-, and N-phenyl-2,4,6-triphenylpyridinium perchlorates) in the electroreduction of carbon dioxide to carbon monoxide. The effect the natures of the substituent and the H+ source have on the efficiency of the process is determined. The main reasons for the occurrence of the electrocatalytic process are identified, and the values of TOF (catalyst speed) and TON (number of revolutions of the catalyst) are calculated. It is shown that the values of TOF and TON fall as the pK of the acid rises.
Determining Characteristics of a Model of Molecular Sorption, Based on an Example of the Separation of Components of Extractional Phosphoric Acid via “Retardation” on Ionites
Authors: Kaznacheev M. A. , Tikhonov N. A. , Khamizov R. Kh.
Published: April 2024

A dynamic model of the transfer and molecular sorption processes inside a sorption column is considered, based on the acid retardation of a gel anion exchanger. A three-layer model of a space filled with a solution is used to describe the process of keeping solution components inside nanosized pores in a multicomponent system. Allowance is made for the heterogeneity of the concentrations of molecules in the pores of the sorbent, caused by the forces acting on polar molecules from the sorption centers. The model allows calculation of changes in the concentrations of components over time inside the sorption column and, based on output concentration curves obtained experimentally, to determine characteristics of the process of holding molecules inside nanosized pores. Results from modeling are compared to experimental data on the purification of industrial extractive phosphoric acid.
Selecting Reference States in Thermodynamic Descriptions of Non-Exchangeable Sorption
Authors: Khokhlova O. N. , Khokhlov V. Yu. , Lisitsyna S. A.
Published: April 2024

Selecting standard and reference states for a thermodynamic description of the non-exchange sorption of substances by ion exchangers is considered a stoichiometric process. It is shown that it is best to choose different reference states for free and sorption centers associated with the absorbed substance, since this allows calculations of the thermodynamic constants and energy characteristics of sorption. Results from calculating thermodynamic characteristics of sorption are presented and discussed for systems with the participation of amino acids (glycine and phenylalanine).
Electron Capture Dissociation by Triclocarban Molecules
Authors: Asfandiarov N. L. , Rakhmeev R. G. , Safronov A. M. , Pshenichnyuk S. A.
Published: April 2024

The formation and decay of molecular negative ions (MNIs) formed during resonant scattering of electrons by triclocarban molecules were studied by dissoiative electron attachment (DEA) spectroscopy. The most intense channel observed in the mass spectrum are MNIs formed at the thermal energy of trapped electrons with a lifetime relative to electron autodetachment of ~2800 μs. The experimental results were interpreted using CAM-B3LYP/6-311+G(d,p) calculations, which made it possible to reveal a number of important features of the geometry of molecular and fragment negative ions. Namely, the most stable geometry of MNIs is such that one of the chlorine atoms is coordinated with two hydrogen atoms of the structural element of urea. The charge on the chlorine atom is ~–0.7e–, which allows us to interpret this state as the result of the “roaming” of the chlorine atom in the MNI. According to calculations, the adiabatic electron affinity (EAa) of the triclocarban molecule is 1.66 eV. Evaluation of EAa in a simple Arrhenius approximation gives 1.2–1.4 eV. An analysis of the potential of the appearance of fragment ions with a C6H3Cl2NH2 structure made it possible to discover the noncovalent structure of these pseudo-MNIs, in which the chlorine atom is coordinated with two hydrogen atoms of the amino group.
Some Features of Quantitative Analysis of Surface Compounds by Laser Desorption Mass Spectrometry
Authors: Pytskii I. S. , Kuznetsova E. S. , Buryak A. K.
Published: April 2024

The results of quantitative analysis of widely used surface samples are shown. Corrosion damage to copper and steel surfaces can be analyzed quantitatively using cobalt chloride as the internal standard. The study also demonstrates the feasibility of comparative quantitative analysis of blue ink using methylene blue homologues as standards. When conducting quantitative analysis on surfaces with inhomogeneous morphology, it has been observed that direct analysis is not possible because of uneven ionization of the sample. It has been found that when analyzing such surfaces, it is necessary to exclude points with a low signal-to-noise ratio from consideration. The work highlights the extensive possibilities of utilizing quantitative analysis in mass spectrometric visualization of the surface. The work is aimed at demonstrating the capabilities of the laser desorption mass spectrometric method for analyzing the surfaces of various materials, which will make this method universal for searching for a wide range of contaminants on the surface of materials of various nature.
Photoinduced Destruction of Complex Cyanides Using Quasi-Monochromatic UVC Radiation of a KrCl Excilamp (222 nm)
Authors: Batoeva A. A. , Tsybikova B. A. , Sizykh M. R.
Published: April 2024

The kinetic regularities of photochemical oxidation of stable complex cyanides (hexacyanoferrates) with persulfate (oxidizing system {UV/S2O}) and hydrogen peroxide (oxidizing system {UV/H2O2}) under the influence of quasi-monochromatic UVC radiation from a KrCl excilamp (222 nm) have been studied. According to the efficiency and rate of the destruction of the target compound, the oxidizing systems under study can be arranged in the following series: {UV/S2O2-8} {UV/H2O2} {UV}. The effective destruction of hexacyanoferrates at micromolar concentrations (≤47 μM) to nontoxic and biodegradable compounds in the combined {UV/S2O2-8} system is due to the high oxidizing ability of reactive oxygen species formed as a result of persulfate photolysis.
Biocorrosion of Copper Under the Impact of Microscopic Fungi
Authors: Belov D. V. , Belyaev S. N. , Yunin P. A.
Published: April 2024

A study is performed of the micromycete biocorrosion of electrical copper M1E and fiberglass FR4 with copper coating, which are used in the production of printed circuit boards. The structure of the surfaces of corroded samples is studied via optical and electron microscopy. Energy dispersive X-ray spectroscopy is used to perform a qualitative and semi-quantitative analysis of chemical elements present in the composition of corrosion products after exposing samples to a bed of micromycetes. An X-ray phase analysis of the products of copper biocorrosion is performed. It is established that microorganisms adhere to the metal surface at the initial stage of micromycetic corrosion, and colonies of them develop. It is suggested that reactive oxygen species (superoxide anion-radical and hydrogen peroxide) participate in the biocorrosion of copper and the functioning of the zerovalent copper–hydrogen peroxide system, triggering a cascade of reactions that result in the destructive oxidation of copper. The role of biofilms of the microscopic fungal colony as the main factor in the mycological corrosion of copper is explained.