bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific Features of the Determination of Xanthophyll Esters under Reversed-Phase HPLC Conditions
Authors: Deineka V. I. , Burzhinskaya T. G. , Blinova I. P. , Deineka L. A.
Published: April 2024

Specific features of chromatographic determination of xanthophyll esters are studied using an example of marigold flower lutein diesters under reversed-phase HPLC conditions. The developed two-column method made it possible to establish that, in samples with a low solubility of carotenoids in the used solvent and on a chromatography column in using a mobile phase with a low solubility of carotenoids, the precipitation of diesters is possible, which detrimentally affects the accuracy of the chromatographic determination. A critical factor in this case isì temperature: the storage of samples (solutions) in a refrigerator is not always advisable, because freezing of the main components is possible. It was shown that the use of a mobile phase containing from 0 to 10 vol % acetonitrile in acetone at a temperature not lower than 20°C is acceptable for the separation of all-trans-lutein diesters from cis-derivatives of lutein and zeaxanthin derivatives on “monomeric” C18-phases.
Resins Based on Polystyrene–Divinylbenzene with Attached Hydrophilized Polyethyleneimine for Ion and Hydrophilic Interaction Liquid Chromatography
Authors: Gorbovskaya A. V. , Popkova E. K. , Uzhel’ A. S. , Shpigun O. A. , Zatirakha A. V.
Published: April 2024

To expand the field of application of anion exchangers based on a copolymer of styrene and divinylbenzene with attached polyethyleneimine, quaternized with glycidol, the following conditions for their synthesis were varied: the amount of the added glycidol, temperature, and duration of synthesis. The influence of these factors on the capacity, selectivity, and efficiency of the resins in the mode of suppressed ion chromatography was studied; in addition, the stationary phases were studied in the mode of hydrophilic interaction liquid chromatography using the Tanaka test. It was shown that the synthesis conditions under study ensure the control of the capacity and selectivity of anion exchangers, while their hydrophilicity changes insignificantly. The behavior of oxoanions on covalently attached resins in the ion chromatography mode was studied for the first time, and the applicability of phases with quaternized polyethyleneimine in the hydrophilic interaction liquid chromatography mode to the separation of sugars, amino acids, water-soluble vitamins, nucleosides, and nitrogenous bases was demonstrated for the first time.
Highly Sensitive Determination of Carbamazepine and Oxcarbazepine and Identification of Their Degradation Products in Material Evidences and Human Cadaveric Liver by Gas Chromatography–Mass Spectrometry
Authors: Pirogov A. V. , Gandlevskii N. A. , Vasil’eva A. A. , Barsegyan S. S. , Nosyrev A. E.
Published: April 2024

The work is devoted to the search for conditions for the sample preparation and determination of carbamazepine and oxcarbazepine and identification of the products of their metabolism and degradation in human liver (post mortem) and material evidences by gas chromatography–mass spectrometry. A QUECHERS approach was developed to the sample preparation of carbamazepine and oxcarbazepine. Amitriptyline was proposed as an internal standard. Degradation products of carbamazepine and oxcarbazepine were studied in model solutions upon alkaline and acid hydrolysis and oxidation; 14 metabolites and degradation products were identified. The main analytical characteristics of the developed procedure were determined. The limits of detection are 0.1 and 0.2 µg/g for carbamazepine and oxcarbazepine, respectively. The developed procedure complies with the Validation Guidelines of the Russian Center for Forensic Medical Examination.
Experience of the Determination of Fluorine in Rocks by X-Ray Fluorescence Spectrometry
Authors: Kuz’mina T. G. , Romashova T. V, , Troneva M. A. , Khokhlova I. V.
Published: April 2024

The main fluorine-concentrating minerals in rocks are mainly apatites, amphiboles, micas, fluorites, sphenes, villiomites, in which fluorine is found in compounds with Ca, Mg, Na. The yield of the X‑ray fluorescence of fluorine depends on the element with which it is chemically bound. Taking into account this factor, three versions of calibration dependences for fluorine in the composition of CaF2, MgF2, and NaF were obtained using pressed tablets. Mixtures of these fluorides with granite, basalt, and limestone were used for calibration. To select an adequate calibration for the determination of fluorine in a batch of unknown samples, it was proposed to use the results of a selective analysis of fused samples of the batch
Origins and Formation of Ion Chromatography
Authors: Rybakova E. V.
Published: April 2024

The origins and ways of formation of ion chromatography are shown. Little-known facts and publications are reflected, and a significant influence of the development of instrument making in HPLC and technologies for the synthesis of low-capacity sorbents on the development of this method is demonstrated. The early history of developments in the field of ion chromatography in the US scientific groups of H. Small (Dow Chemical and Dionex Corp.) and J. Fritz (Iowa State University) is described, and the scientific works and key achievements of these scientists are analyzed.
Effects of Comorbidities on the Profile of Volatile Organic Compounds in the Exhaled Breath of Lung Cancer Patients
Authors: Gashimova E. M. , Temerdashev A. Z. , Porkhanov V. A. , Polyakov I. S. , Perunov D. V.
Published: April 2024

The diagnostics of lung cancer by exhaled breath is a promising field in medicine; however, many patients with lung cancer have other concomitant diseases that could impact the accuracy of diagnostic techniques. This work is devoted to a GC–MS study of possible effects of the most common comorbidities: chronic heart failure, hypertension, obesity, diabetes mellitus, and atherosclerosis on the composition of volatile organic compounds in the exhaled breath of patients with lung cancer. Components and their ratios, which were different in groups of patients with lung cancer and diverse concomitant diseases, were found.
Selective Adsorbents Based on Imprinted Glucose Oxidase
Authors: Pidenko P. S. , Presnyakov K. Yu. , Drozd D. D. , Burmistrova N. A.
Published: April 2024

A procedure for the synthesis of a highly selective adsorbent based on an imprinted protein (IP), glucose oxidase (GO), and commercially available SiO2 microparticles for the sorption of mycotoxin zearalenone produced by fungi of the Fusarium species is developed. The use of 3D fluorescence spectroscopy for the control of the process of IP purification is proposed for the first time. A possibility of replacing the zearalenone molecule as a template molecule with structural analogues with lower toxicity is assessed. The analytical characteristics of the determination of zearalenone using imprinted GO as a receptor element in enzyme immunoassay are determined: the limit of detection is 5 ng/mL, the linear analytical range is 11–112 ng/mL. High sorption characteristics of the synthesized adsorbent based on IP (sorption capacity—7.6 μg/mg sorbent; imprinting factor—2.5) are shown.
Rapid Colorimetric Determination of Biologically Active Organic Analytes
Authors: Sokolova T. A. , Kosyreva I. V. , Doronin S. Yu.
Published: April 2024

Four types of reactions (azo coupling, protolytic and oxidative condensation, ion association), accompanied by the formation of hydrophobic colored analytical forms of corresponding organic analytes, are proposed on an example of biologically active substances (aromatic amines, α-amino acids, antibiotics of aminoglycoside and β-lactam series, anionic surfactants). It is shown that, in these systems, the hydrophobicity of both the initial reactants, e.g., tetrafluoroborates of diazonium salts, and analytical forms (azo compounds, Schiff bases, Ruemann’s purpura, ion associates with surfactants) can be increased. Possibilities of various methods for the derivatization of organic analytes with the formation of colored analytical forms with increased hydrophobicity for the best fixation on solid matrices and the development of test systems on their basis, which can be used to control the quality of various samples with rather good performance characteristics, are considered.
Determination of Umifenovir and Its Metabolites by High-Performance Liquid Chromatography with Combined Mass Spectrometric Detection
Authors: Sypalov S. A. , Ul’yanovskii N. V. , Kosyakov D. S. , Lebedev A. T.
Published: April 2024

An approach to the highly sensitive and selective determination of the bromine-containing antiviral drug umifenovir (Arbidol) and its metabolites in natural and waste water, activated sludge, and bottom sediments by chromatography-mass spectrometry based on a combination of two techniques– inductively coupled plasma mass spectrometry (ICP MS) and electrospray ionization high-resolution mass spectrometry (ESI HRMS) is developed. Reversed-phase chromatographic separation and detection based on ESI HRMS provide the reliable detection and identification of analytes in complex matrices, while the use of ICP-MS with 79Br signal detection makes it possible to exclude matrix effects and use a single analytical standard for quantitative analysis. The use of solid-phase extraction and pressurized liquid extraction as sample preparation methods made it possible to achieve limits of detection at a level of 0.2 ng/L and 2 µg/kg for liquid and solid samples, respectively. The developed approach was successfully tested in the analysis of real samples. It is shown that the concentrations of analytes in urban wastewaters are in the range 4.4–260 ng/L. The highest concentration (up to 3.7 mg/kg) is characteristic of activated sludge, which acts as an effective sorbent for umifenovir and its transformation products.
Nanoobjects for the Luminescence Determination of Fluoroquinolones
Authors: Shtykov S. N. , Smirnova T. D. , Rusanova T. Yu.
Published: April 2024

Fluoroquinolones are the most successful antibiotics, which also show antiviral and antitumor activity. The widespread use of fluoroquinolones in medicine, pharmaceutical chemistry, veterinary medicine and in animal, poultry, and fish feeds requires continuous improvement of methods for their determination in various samples. Sensitized fluorescence based on resonance electronic excitation energy transfer (RET) during the formation of chelates with terbium and europium ions is a promising and highly sensitive method for the determination of fluoroquinolones. This review analyzes the use of two types of nanoobjects—liquid micellar nanosystems and quantum dots based on the nanoparticles of silver, gold, and semiconductors and carbon, magnetic, and other nanomaterials—for increasing the efficiency of energy transfer and the sensitivity of the determination of fluoroquinolones in various samples. The terminology used in the inductive-resonance and exchange-resonance mechanisms of energy transfer is considered, and the fundamental difference in RET between liquid and solid types of nanoobjects is shown. Linear dynamic ranges of determined concentrations, limits of detection, and examples of practical application of sensitized fluorescence to the determination of fluoroquinolones in real samples with the use of nanoparticles and micellar nanosystems are tabulated.
Analysis of the Chemical Composition and Structure of Micrometer-Thick Complex Oxide Films: A Case Study of a MgAl2O4 Film on SiO2 Using Electron Probe Microanalysis and Confocal Raman Spectroscopy
Authors: Bulatov V. A. , Shchapova Yu. V. , Zamyatin D. A. , Sushanek L. Ya. , Kamenetskikh A. S. , Votyakov S. L.
Published: April 2024

Methodological approaches to both qualitative structural analysis and quantitative compositional analysis of transparent complex oxide films on dielectric substrates, performed using a Horiba LabRAM HR800 confocal Raman spectrometer and a Cameca SX100 electron probe microanalyzer, are described. The studies were carried out using magnesium–aluminum spinel films of a thickness of 1–3 µm on a quartz glass substrate, obtained by magnetron sputtering. The characterization of the film structure consisted of recording 3D arrays of its Raman spectra based on z depth profiling. The film has a disordered spinel structure with a partially reversed distribution of Mg and Al cations over octa- and tetra-positions. Operation parameters are identified to evaluate the concentration of structure-forming elements (Mg and Al) and impurities (Ti, Cr, Ca, P, Fe, Ni, and Gd) in the film using various X-ray emission lines (optimal accelerating voltage, etc.). The performance of the procedure was determined, and its capabilities and limitations were assessed. The resulting data on the chemical composition of the film are presented.
Study of Sorption of Chlortetracycline Hydrochloride and Its Subsequent Determination by Capillary Zone Electrophoresis
Authors: Gorodilova A. I. , Lebedeva E. L. , Petrova Yu. S. , Neudachina L. K.
Published: April 2024

The work deals with the development of an approach to the determination of chlortetracycline, which combines the preconcentration of the analyte with its subsequent determination by capillary zone electrophoresis. The conditions that ensure the lowest value of the limit of determination for chlortetracycline in aqueous solutions using a Kapel-105M capillary electrophoresis system (Lumex, Russia) are determined, i.e., temperature, time and pressure of sample injection, background electrolyte composition, and detection wavelength. It is shown that the stability of a chlortetracycline solution is maximum at a storage temperature of 0.5°С in the absence of buffer systems or in using a dilute ammonium acetate buffer solution. It is found that the recovery of chlortetracycline by strongly acidic cation exchangers KU-1, KU-2 is higher compared to that by KB-4 and KB-4P2, bearing weakly acidic functional groups. The conditions under which the recovery of the analyte by KU-1 from a phosphate buffer solution is about 90% are determined.
Sorption Preconcentration of Quercetin Using Molecularly Imprinted Phloroglucinol–Melamine–Formaldehyde Resins
Authors: Petrova Yu. Yu. , Bulatova E. V. , Kukhtenko E. V.
Published: April 2024

Hydrophilic quercetin-imprinted phloroglucinol–melamine–formaldehyde resins are obtained. The obtained samples are studied by Fourier-transform IR spectroscopy and laser diffraction. The phloroglucinol–melamine ratio (3 : 1) is optimized at the sorption capacity of the molecularly imprinted resin (1.7 μmol/g) with respect to quercetin 2.6 times higher than that of the non-imprinted resin. It is shown that the kinetics of quercetin rebinding by both molecularly imprinted and non-imprinted resins obeys the pseudo-second order model, and the isotherms follow the Freundlich model, which indicates the inhomogeneity of the resin surface. The resin imprinted with quercetin demonstrated high selectivity to morine (a structural analogue of quercetin of the flavonol class) and caffeine. At that it is shown that quercetin can be used as a pseudotemplate for the separation and preconcentration of naringenin (a representative of flavanones) and rutin (a representative of flavonols).
Synthesis and Thermal Stability of Manganese(III) Acetylacetonate
Authors: Eshmakov R. S. , Prolubshchikov I. V. , Zlomanov V. P.
Published: April 2024

The dependence of the stability of Mn(C5H7O2)3 modifications on the properties of the solvent chosen for recrystallization is considered. Low-polarity solvents with a low dielectric permittivity enhance intermolecular interactions, which leads to the formation of the β-Mn(C5H7O2)3 modification during the synthesis of Mn(C5H7O2)3 from chloroform solutions. The use of mixtures of chloroform with petroleum ether makes it possible to control supersaturation, the rate of formation, and growth of phase nuclei due to the evaporation of chloroform under isothermal conditions. The use of polar solvents for recrystallization favors the formation of γ-Mn(C5H7O2)3. The composition of the thermal decomposition products of β‑Mn(C5H7O2)3 in a dry inert atmosphere has been determined by X-ray powder diffraction, IR spectroscopy, thermogravimetric and mass spectral analysis, and differential scanning calorimetry. In the temperature range 140–240°C, β-Mn(C5H7O2)3 melts to form Mn(C5H7O2)2. At temperatures of 500–550°С, Mn(C5H7O2)2 decomposes to a mixture of MnO, Mn3O4, Mn2O3, and carbon.
Equation of State of Periclase Based on Planck–Einstein Functions
Authors: Perevoshchikov A. V. , Maksimov A. I. , Babayan I. I. , Kovalenko N. A. , Uspenskaya I. A.
Published: April 2024

The paper presents an extension of the Voronin–Kutsenok method for joint description of both thermochemical and bulk data with combination of Planck–Einstein functions and modified Tait equation. Two approaches based on the Gibbs and Helmholtz energy descriptions were proposed. Magnesium oxide (periclase) was chosen as the test system. The parameters of the equation of state were optimized using published data over a broad range of thermodynamic variables (up to 3000 K and 145 GPa). The predictive power of both approaches was estimated.
Ion-Selective Membrane Electrode for Determination of the Octahydrotriborate Anion
Authors: Kopytin A. V. , Turyshev E. S. , Madraimov M. Sh. , Kubasov A. S. , Zhizhin K. Yu. , Shpigun L. K. , Kuznetsov N. T.
Published: April 2024

An ion-selective electrode (ISE) based on a plasticized polyvinyl chloride membrane chemically doped with tetradecylammonium octahydrotriborate ([(С10H21)4N+]) has been developed. It is shown that the electrode has a reversible potentiometric response with respect to the octahydrotriborate anion in the presence of a number of other inorganic anions. The influence of the concentration of the electrode-active material and the nature of the plasticizer in the membrane phase on the electrochemical characteristics of the fabricated sensor have been studied. The optimal composition of the ion-sensitive membrane has been found. It has been found that the developed sensor provides a wide range of detectable concentrations of(1 × 10–7…1 × 10–2) and a low detection limit (10–7.3 M). The new ISE can be recommended for direct potentiometric detection of free octahydrotriborate anions in technological aqueous solutions.
Isolation of Concentrated Fractions of Components from Solutions in a Cascade of Multistage Extraction Columns by Recycling Liquid–Liquid Chromatography
Authors: Kostanyan A. E. , Tsareva Yu. V. , Belova V. V.
Published: April 2024

The paper describes the results of an experimental study of the extraction isolation of concentrated fractions of components from solutions by recycling liquid–liquid chromatography in a setup composed of five multistage extraction columns connected in series. The process includes multiple injection of the solution of the components into the system. The adequacy of the previously developed mathematical model to the real process is confirmed and the validity of the obtained equations for the modeling and development of various types of separation processes is demonstrated.
Thermodynamic Study of a Volatile Complex of Magnesium Benzoyltrifluoroacetonate with N,N,N',N'-Tetramethylethylenediamine
Authors: Vikulova E. S. , Sysoev S. V. , Sartakova A. V. , Rikhter E. A. , Rogov V. A. , Nazarova A. A. , Zelenina L. N. , Morozova N. B.
Published: April 2024

To expand the library of volatile magnesium precursors certified for effective use in chemical gas-phase deposition of the corresponding oxide or fluoride layers, a thermodynamic study of the mixed ligand complex Mg(tmeda)(btfac)2 (tmeda is N,N,N',N'-tetramethylethylenediamine, btfac is benzoyl trifluoroacetonate) have been performed. The melting process has been studied using DSC (Tm = 459.4 ± 0.3 K,= 42.9 ± 0.4 kJ/mol); the sublimation process has been studied using the flow (transfer) method in the temperature range 407–447 K (= 163 ± 6 kJ/mol, ΔsublS427 = 293 ± 14 J/(mol K)). The substance passes into the gas phase with partial decomposition. Thermodynamic modeling of the composition of condensed phases formed from Mg(tmeda)(btfac)2 with the addition of H2 or O2 has been performed depending on the temperature (700–1300 K), total pressure (133–13 332 Pa), and the ratio of the reagent gas to the precursor (0–300). The data obtained can be used to determine the experimental parameters of the processes for obtaining functional layers. Comparison of the results with a similar trifluoroacetylacetonate complex made it possible to quantitatively reveal the effect of replacing the methyl group in the anionic ligand with a phenyl one.
Role of SiO2 in the Formation of Hydrate Phases in the Presence of СН4/CO2
Authors: Bozhko Yu. Yu. , Zhdanov R. K. , Gets K. V. , Subbotin O. S. , Belosludov V. R.
Published: April 2024

The effect of silicon dioxide nanoparticles on the formation of hydrate phases in the presence of CH4/CO2 has been studied. The theoretical experiment has been carried out by molecular dynamics methods at initial pressures in the system of 2.4 and 1.2 MPa and a temperature of 271 K for methane and carbon dioxide systems. The results showed that in the presence of silicon dioxide nanoparticles, the induction time of the methane hydrate formation decreased by 79%, and the amount of methane trapped in the hydrate cavity increased by 55.8% at a pressure of 2.4 MPa. In the presence of silicon dioxide nanoparticles, the induction time for the formation of carbon dioxide hydrate decreased by 62%, and the amount of carbon dioxide trapped in the hydrate cavity increased by 27.8% at a pressure of 1.2 MPa.
Synthesis and Investigation of Na1 – xR0.33xTiO2(PO4)3 (R = Y or La) Phosphates
Authors: Sedov V. A. , Glyadelova Ya. B. , Asabina E. A. , Pet’kov V. I.
Published: April 2024

Phosphates Na1 – xR0.33xTi2(PO4)3 (R = Y or La; 0 ≤ х ≤ 1) were synthesized by the Pechini process and characterized by X-ray diffraction, electron microscopy with microprobe analysis, and IR spectroscopy. The systems exhibit isodimorphism to form a series of solid solutions belonging to the NaZr2(PO4)3 (NZP) structural type and crystallizing in space group Rc or RThe Rietveld structural studies confirmed the isomorphic miscibility of sodium and the rare-earth element in the interstices of the NZP structure. The unit cell parameter с in the phosphates studied tends to increase, and the parameter а tends to decrease, in response to rising temperature, which trends are typical of NZP phosphates.
Thermodynamic Properties of Solutions in the H2O–Na2SO4–Al2(SO4)3 System
Authors: Nesterov A. V. , Demchenko A. M. , Potashnikov A. A. , Voskov A. L. , Kovalenko N. A. , Uspenskaya I. A.
Published: April 2024

The vapor pressure in the H2O–Na2SO4–Al2(SO4)3 system at 15, 25, and 35°C was measured by a static method. The vapor pressure in the H2O–Al2(SO4)3 and H2O–Na2SO4–Al2(SO4)3 systems at 25 and 50°C was measured by the dew point method. A set of parameters of the Pitzer–Simonson–Clegg (PSC) model was determined to describe adequately vapor– liquid equilibria in the H2O–Al2(SO4)3 and H2O–Na2SO4–Al2(SO4)3 systems in the temperature range from 15 to 50°С.
Initial Stages of the Formation of the Supramolecular Structure of Ca and Mg Oxides
Authors: Sakovich R. A. , Shaulov A. Yu.
Published: April 2024

The optimal geometries of (CaO)n and (MgO)n clusters at n = 2–30 have been found and the enthalpies of formation of 1D, 2D, and 3D structures have been determined using quantum-chemical DFT calculations. The calculation demonstrates that the formation of linear chains of Ca and Mg oxides practically does not occur, while the formation of two-dimensional (tiled) and three-dimensional (cubic) structures proceeds with a large release of energy. The competing process of formation of molecular rods consisting of planar six-membered rings (MO)3 has been considered, and it has been shown to proceed not through the stage of preliminary formation of six-membered rings, but directly from monomer units.
Group Extraction of the Rare-Earth Elements by Alkyl Phosphine Oxides of the Hexyl–Octyl Series
Authors: Tumanov V. V. , Storozhenko P. A. , Grachev A. A. , Fedin O. I.
Published: April 2024

Samples of monoalkyl and mixed-alkyl phosphine oxides of the hexyl–octyl series were synthesized previously by the Grignard method. Here, the group extraction of rare-earth metals contained simultaneously in their nitrate solutions has been studied using then-synthesized alkyl phosphine oxides. Extraction isotherms for the recovery of the total of lanthanides, scandium, and thorium from nitrate solutions have been obtained. Trihexyl phosphine oxide (THPO) exhibits the highest efficiency under these conditions. Trioctyl phosphine oxide (TOPO) exhibits the best selectivity to heavy-group lanthanides, which makes it useful for the recovery of the heavy-group lanthanide fraction. In addition, scandium and thorium were extracted completely, which in turn indicates the usefulness of phosphine oxides for their extraction. The separation factors have been determined for the entire lanthanides series.
Estimation of the Standard Enthalpy of Formation of Crystalline Alkali Metal Borates
Authors: Tupitsin A. A. , Bychinskii V. A. , Shtenberg M. V. , Fomichev S. V. , Koroleva O. N.
Published: April 2024

A structure–property correlation has been developed, which makes it possible to choose the optimal values of the enthalpy of formation of alkali metal borates, for which, according to the data of various experimental works and reference publications, wide variations are observed. Using this correlation, the enthalpy of formation of unstudied alkali metal borates can be reasonably estimated. It has been found that the contribution of B2O3 to the enthalpy of formation is the same not only for alkali metal borates but also for Ba, Ca, and Pb borates, for whose enthalpy of formation a structure–property correlation has also been established. This suggests the suitability of the obtained correlations for estimating the enthalpy of formation in the borate series, where the value is known only for one member of the series, as well as the possibility of estimating the enthalpy of formation of mixed borates of different metals.
Simulation of Spin Selectivity of Electrical Conductivity of Chiral Platinum Nanotubes
Authors: D’yachkov P. N. , Lomakin N. A.
Published: April 2024

To study the electronic and spin properties of single-walled platinum nanotubes, two rows of chiral nanotubes have been calculated by the relativistic method of symmetrized linearized augmented cylindrical waves: Pt(5, n2) with 1 ≤ n2 ≤ 4 and Pt(10, n2) with 1 ≤ n2 ≤ 9 and radii from 2.24 to 7.78 Å. In all tubes, the intersection of the top of the valence band and the bottom of the conduction band with the Fermi level is observed, which is characteristic of compounds with a semi-metallic band structure. The spin–orbit coupling manifests itself as a splitting of nonrelativistic dispersion curves, which can exceed 0.5 eV for near-Fermi bands and decreases upon transition to the internal states of the valence band and nanotubes of larger diameter. The spin densities of states for electrons with spin up and down at the Fermi level are noticeably different, which can be used to create pure spin currents through nanotubes using alternating electrical voltage. The (5, 3) and (10, 7) nanotubes are the most suitable for this.
Synthesis of Silver Nanoclusters and Nanoparticles in the Medium of Hyperbranched Polyester Polyamine, and the Morphology and Aggregation Properties of the Metal–Polymer Nanocomposite
Authors: Prytkov V. A. , Khannanov A. A. , Evtyugin V. G. , Gataulina A. R. , Kutyreva M. P.
Published: April 2024

A procedure was developed for the single-step synthesis of a metal–polymer nanocomposite based on silver nanoparticles and second-pseudogeneration superbranched polyester functionalized along the periphery with 3-[(2-aminoethyl)amino]propionate. Under the conditions of the synthesis in the medium of H2O or DMSO, hyperbranched polyester decorated with ethylenediamine moieties can act as both a reductant of the nanoscale silver state and a stabilizer of it. The synthesized composite nanomaterial is formed by aggregates of hyperbranched polyester polyamine doped with Ag(0) nanoclusters and nanoparticles of spheroidal symmetry with a face-centered cubic crystal lattice. The hydrodynamic diameter of aggregates and the diameter of particles increase with increasing molar ratioand are 34–90 and 7–14 nm, respectively.
Extraction of Actinides and Lanthanides(III) from Nitric Acid Solutions with Mixtures of N-(Diphenylphosphoryl)-N'-propylureas with ω-Nitrogen-Containing Groups and Dinonylnaphthalenesulfonic Acid
Authors: Turanov A. N. , Karandashev V. K. , Baulina T. V. , Goryunov E. I. , Brel V. K.
Published: April 2024

Extraction of uranium, thorium, and lanthanide(III) ions from nitric acid solutions with mixtures of dinonylnaphthalenesulfonic acid and N-(diphenylphosphoryl)-N'-n-propylureas containing imidazolyl, diethylamino, pyrid-2-yl, and 2-oxopyrrolidine fragments has been studied in organic solvents. Considerable synergetic effect on extraction of metal ions with mixtures of dinonylnaphthalenesulfonic acid and N-(diphenylphosphoryl)-N'-[3-(2-oxopyrrolidino)propyl]urea has been revealed. Stoichiometry of extracted complexes has been determined. Effect of extractant strucuture, organic diluent nature, and HNO3 content in aqueous phase on extraction efficiency of metal cations into organic medium has been accessed.
Modeling of the Phase Assemblage of the LiF–Li2CrO4–LiRbCrO4–LiKCrO4 Stable Tetrahedron of the Li+, K+, Rb+||F–,
Quaternary Reciprocal System
Authors: Burchakov A. V. , Myakin’kova O. N. , Umarova A. S. , Demina M. A. , Yakovlev V. M. , Kondratyuk I. M. , Egorova E. M.
Published: April 2024

Here, phase equilibria in a quaternary reciprocal system comprised of fluorides and chromates of lithium, potassium, and rubidium was studied. The phase assemblage of the system was partitioned to stable simplices. The Li–Li2CrO4–LiRbCrO4–LiKCrO4 stable tetrahedron was selected as the subject matter of this study due to its undoubted scientific importance. The analysis of the boundary elements predicted, and the DTA experimental study of phase equilibria in the system proved, that monovariant phase equilibrium L ⇄ LiF + α-Li2CrO4 + (LiKxRb1 – xCrO4)ss is realized in the system, described by line Е 397–Е 400; the characteristics of the minimum point of this monovariant equilibrium (Min◻ 367) were elucidated. The mass balance of the phase reaction for this point is presented. A 3D model of the phase assemblage of the system was designed based on experimental data. The system preserves the continuity of (LiKxRb1 – xCrO4)ss solid solutions. The mixture whose composition corresponds to point Min◻ 367 has a relatively low melting temperature and can serve as a material for new fusible electrolytes in chemical current sources; it can also be of interest as an electrolytic bath for recovery of metals from melts.
Thermal Stability of Nanocrystalline Zinc Sulfide ZnS
Authors: Sadovnikov S. I. , Sergeeva S. V.
Published: April 2024

Nanocrystalline zinc sulfide (ZnS) powders are prepared via hydrothermal deposition from aqueous solutions of zinc nitrate and sodium sulfide in the presence of sodium citrate or Trilon B. The average particle sizes of the product ZnS nanopowders ranging from 2 to 9 nm are tuned via varying the batch concentrations of the reagents. Air-annealing of as-prepared ZnS nanopowders at temperatures of 280 to 530°C oxidizes cubic zinc sulfide to hexagonal zinc oxide. The oxidation of the finest-grained zinc sulfide nanopowders having a particle size of 2 nm starts at 280–330°C, while the coarsest-grained nanopowder having a particle size of 9 nm starts to oxidize at 530°C. In the coarsest-grained ZnS powder, the particle size increases as little as from 9 to 12 nm when temperature rises to 530°C, while the finest-grained nanopowders have their particle sizes increase from 2 to 9 nm in response to the same rise in temperature.
Complexes of Zinc Nitrate and Lanthanide Nitrates with Urea in the 1 : 2 Ratio
Authors: Karavaev I. A. , Savinkina E. V. , Ponkrashina S. S. , Grigor’ev M. S.
Published: April 2024

Coordination compounds [Zn(H2O)4(Ur)2](NO3)2, [M(H2O)2(Ur)2(NO3)3] (M = Ce, Nd), and [Dy(H2O)(Ur)2(NO3)3] have been synthesized by the reaction of nitrates of zinc or rare earth elements with urea (Ur) in an aqueous solution. Their composition has been determined and structural features have been established using elemental analysis, IR spectroscopy, and X-ray diffraction analysis. For the zinc complex, a polymorphic transition has been found at 181 K.
New Method for Preparation of Composite Based on Montmorillonite and Graphene Oxide
Authors: Ioni Yu. V. , Sapkov I. V. , Chentsov S. I. , Efremova E. I. , Gubin S. P.
Published: April 2024

A new method for preparation of a composite based on graphene oxide and montmorillonite has been proposed. A comparative characteristic of the adsorption rate for montmorillonite, graphene oxide, and a composite based on them is given. It is shown that the composite has the best adsorption properties with respect to methylene blue. The samples have been studied by IR and Raman spectroscopies, SEM, X-ray powder diffraction, and TGA/DTA. The resulting composite material can be widely used as sorbents for organic dyes in an aqueous medium and organic solvents.
Na5Rb7Sc2(WO4)9: Yb3+, Er3+: Luminescence Properties and Prospects for Non-Contact Thermometry
Authors: Lipina O. A. , Spiridonova T. S. , Baklanova Ya. V. , Khaikina E. G.
Published: April 2024

Trigonal solid solutions Na5Rb7Sc1.95Yb0.05 – xErx(WO4)9 (x = 0.0025–0.0375) and Na5Rb7Sc2 – 5y-Yb2yEr3y(WO4)9 (y = 0.005–0.015) based on ternary tungstate Na5Rb7Sc2(WO4)9 have been obtained by ceramic technology and their luminescence properties have been studied. Excitation of powders by infrared radiation of the laser module (λex = 980 nm, Pmax = 45 mW/mm2) leads to the appearance of a bright green emission. The highest intensity of the bands at 515–540 nm (2H11/2 → 4I15/2), 540–575 nm (4S3/2 → 4I15/2), and 645–680 nm (4F9/2 → 4I15/2) is observed for sample Na5Rb7Sc1.95Yb0.02Er0.03(WO4)9. For a given composition, the power and temperature dependences of optical characteristics have been studied, a mechanism for energy transfer between optical centers has been proposed, and chromaticity coordinates have been determined. Based on the data obtained, it has been concluded that Na5Rb7Sc1.95Yb0.02Er0.03(WO4)9 can be used as a material for non-contact luminescent thermometry.
Prediction of the Melting Points of Double Halides
Authors: Kiseleva N. N. , Dudarev V. A. , Stolyarenko A. V. , Dokukin A. A. , Sen’ko O. V. , Kuznetsova Yu. O.
Published: April 2024

The atmospheric pressure melting points of binary halides ABHal3, ABHal4, A2BHal4, A2BHal5, and A3BHal6 (A and B are various elements; Hal = F, Cl, Br, or I) were predicted. Calculations were made using our developed system of machine learning. Computer models were searched by analyzing information on the already known melting points of halides. The unknown melting points of the halides were predicted using only the values of the properties of the elements A, B, and Hal. It was shown that the programs based on the methodology of ensembles of machine learning algorithms make the most accurate estimates of melting points (the mean absolute errors determined by the cross-validation method in the leave-one-out cross validation mode were in the range of 29–52 K, depending on the halide composition and the chosen algorithm). The coefficient of multiple determination for the models used for prediction was no lower than 0.7.
Structure and Electrical Conductivity of Bismuth- and Germanium-Doped Calcium Molybdates
Authors: Kaimieva O. S. , Mikhailovskaya Z. A. , Buyanova E. S. , Petrova S. A. , Pankrushina E. A.
Published: April 2024

Ca1 – 2xBi2xMo1 – xGexO4 solid solutions with a scheelite-like structure (space group I41/a) and the homogeneity range х = 0.0–0.4 were prepared using standard ceramic technology. The unit cell parameter с and unit cell volume increase as the dopant concentration increases due to the changing size of Ca/BiO8 polyhedra. The predominant thermal expansion of Ca/BiO8 polyhedra was inferred from the temperature-dependent unit cell parameters and Raman spectral patterns. The Ca/Bi–O and Mo/Ge–O bond lengths were calculated. The increasing dopant concentration decreases the thermal expansion coefficient of the ceramics and increases the electrical conductivity and activation energy of the complex oxides compared to the matrix compound. The effective oxygen diffusion coefficient is determined.
Hydrothermal Synthesis and Photocatalytic Properties of Cobalt-Doped Tungsten Oxide
Authors: Zakharova G. S. , Podval’naya N. V. , Gorbunova T. I. , Pervova M. G.
Published: April 2024

Hexagonal tungsten trioxide–base interstitial solid solutions of general formula CoxWO3, where 0.01 ≤ x ≤ 0.09, were prepared hydrothermally. The dopant homogeneity extent was found to depend on рН in the working solution. Interstitial solid solutions with the highest Co2+ concentrations were formed at рН of 2.3. The CoxWO3 samples with a fiber-like morphology with a fiber diameter of ca. 40 nm, which were prepared at рН of 2.3, had the highest specific surface area, equal to 38.6 m2/g. The key parameter for the stability of the CoxWO3 crystal structure appeared to be ammonium ions residing in the hexagonal channels of the crystal structure. When tested as photocatalysts of 1,2,4-trichlorobenzene oxidation under the UV light, the prepared samples showed high chloroarene conversions and low selectivities to yield a wide range of organic compounds, including chlorine-free ones.
Extraction of REE(III) with Mixtures of 2,4,6-tris(Diarylphosphoryl)-1,3,5-triazines and Picrolonic Acid
Authors: Turanov A. N. , Karandashev V. K. , Artyushin O. I. , Smirnova E. V. , Bodrin G. V. , Brel V. K.
Published: April 2024

Considerable synergetic effect has been revealed on extraction of REE(III) ions from chloride solutions with mixtures of picrolonic acid and tris(diarylphosphoryl)-1,3,5-triazines in 1,2-dichloroethane due to formation of hydrophobic mixed-ligand REE(III) complexes. Parameters of extraction equilibrium and stoichiometry of resulting complexes have been determined. Effect of aqueous phase composition, organic solvent nature, and extractant structure has been studied. The largest synergetic effect has been observed in the system with tris(ditolylphosphoryl)-1,3,5-triazine.
Synthesis and Crystal Structures of (HL)2[B10Cl10]·3CH3CN (L = Bipy, Phen)
Authors: Avdeeva V. V. , Vologzhanina A. V. , Nikiforova S. E. , Buzanov G. A. , Malinina E. A. , Kuznetsov N. T.
Published: April 2024

Reactions of (Et3NH)2[B10Cl10] and organic ligands 2,2'-bipyridyl (Bipy) and 1,10-phenanthroline (Phen) in the acetonitrile–trifluoroacetic acid system have yielded compounds of composition (HL)2[B10Cl10]·3CH3CN (L = Bipy, Phen). The compounds have been characterized by IR spectroscopy, elemental analysis, and X-ray diffraction (CCDC nos. 2224377 and 2224378). It has been shown that in the presence of trifluoroacetic acid, protonation of organic ligands occurs with the formation of bipyridylium and phenanthrolinium salts, which are stabilized by the decachloro-closo-decaborate anion. It has been found that the cations participate in the formation of hydrogen bonds with the solvate molecules of acetonitrile, while only weak C–H…Cl and B–Cl…π interactions are observed for boron cluster anions.
Features of Copper(I) Complexation with Benzimidazole Derivatives in the Presence of the closo-Dodecaborate Anion
Authors: Nikiforova S. E. , Kubasov A. S. , Belousova O. N. , Avdeeva V. V. , Malinina E. A. , Kuznetsov N. T.
Published: April 2024

The process of copper(I) complexation with organic ligands as luminophores 1-(1-methylbenzimidazol-2-yl)-N-phenylmethanimine (L1), 1-ethyl-2-(4-methoxyphenyl)azobenzimidazole (L2), and 1-(1-benzylbenzimidazol-2-yl)-N-cyclohexylmethanimine (L3) in the presence of the closo-dodecaborate anion [B12H12]2– has been studied. It has been shown that in acetonitrile, a redox reaction proceeds to form copper(II) tris-chelate complexes [CuIIL3][B12H12]. Using diiodomethane as a solvent, we have succeeded in stabilizing copper in the +1 oxidation state; as a result, mixed-ligand binuclear complexes [CuI2L2(μ-I)2] containing no boron cluster anion have been isolated. The structures of complexes [CuII(L1)3][B12H12] and [CuI2(L3)2(μ‑I)2] have been determined by X-ray diffraction.
Synthesis of CeO2 and CeO2/C Using Powdered Cellulose and Powdered Cellulose–Sucrose as a Template
Authors: Shishmakov A. B. , Mikushina Yu. V. , Koryakova O. V.
Published: April 2024

CeO2 nanooxide has been synthesized from cerium(III) nitrate using powdered cellulose (PC) and its mixture with sucrose as templates. The removal of templates from composites (PC–Ce(NO3)3 and PC–sucrose–Ce(NO3)3) has been carried out in two ways: via direct burning-out of PC (PC–sucrose) in an air flow and via burning-out of the carbonizate after template pyrolysis. Using UV and IR spectroscopy, X-ray powder diffraction (XRD), and electron microscopy, the influence of the template composition and the method of its removal on the physicochemical characteristics of CeO2 nanoparticles has been studied. A carbon–oxide material CeO2/C has been synthesized by pyrolysis of PC–Ce(NO3)3 and PC–sucrose–Ce(NO3)3 composites. It has been established that the pyrolysis of PC–Ce(NO3)3 and PC–sucrose–Ce(NO3)3 leads to the formation, in the carbonizate, of CeO2 (cerianite) nanoparticles with sizes of 3–4 and 1–2.5 nm, respectively. The average diameter of nanoparticles (according to XRD data) is 3.8 and 2.3 nm. CeO2/C synthesized from the PC–sucrose–Ce(NO3)3 composite contains cerium(III) oxide. All CeO2 nanoparticles in the carbon matrix have a hydroxyl–hydrate cover. The burning of the organic or carbon matrix of the composites leads, regardless of the template used and synthesis conditions, to the formation of CeO2 (cerianite) nanoparticles with the same average diameter of 25 ± 1 nm (according to XRD data), containing an admixture of the Ce(III) phase and having a hydroxyl–hydrate cover. Carbon is present in the material in trace amounts (≤0.15 wt %). The size scatter of CeO2 nanoparticles produced by burning out PC from the PC–Ce(NO3)3 composite is 15–30 nm. In those cases when the organic component from PC–sucrose–Ce(NO3)3 is subjected to burning or the pyrolysis stage of both composites is included in the synthesis process, the appearance of a fraction of larger CeO2 particles (50–60 nm) is observed. The correctness of the obtained data has been confirmed in the course of the model process of hydrogen peroxide decomposition.
Estimation of the Standard Heat Capacity of Crystalline Alkali Metal Borates
Authors: Tupitsin A. A. , Yas’ko S. V, , Bychinskii V. A. , Fomichev S. V. , Shiribazarova E. B. , Koroleva O. N.
Published: April 2024

A structure–property correlation was developed that makes it possible to choose the optimal values of the standard heat capacity of alkali metal borates, for which, according to the data of various experimental works and reference publications, wide variations are observed. This correlation enables one to estimate the standard heat capacity of unstudied alkali metal borates with sufficient validity. To ensure the reliability of the correlation, a critical analysis was made of the initial data taken from reference publications and original experimental works. Our own processing of experimental measurements of the heat capacity and the enthalpy increment was performed to verify the reliability of the literature values of the standard heat capacity of alkali metal borates.
Extraction-Pyrolytic Synthesis and Luminescent Properties of Borates La0.95Eu0.05BO3 : Sm and La0.95Eu0.05(BO2)3 : Sm
Authors: Steblevskaya N. I. , Belobeletskaya M. V.
Published: April 2024

Orthoborates La0.95–хEu0.05SmхBO3 and metaborates La0.95 – хEu0.05Smх(BO2)3 (х = 0.025, 0.05, 0.075, 0.1) have been obtained under optimal conditions by extraction-pyrolytic method at lower temperature and shorter time as compared with the known methods. Increase in Sm3+ ion concentration leads to decrease of unit cell volume in La0.95 – хEu0.05SmхBO3 (aragonite structural type) and La0.95 – хEu0.05Smх(BO2)3 (monoclinic modification of α type). The larges changes in luminescence excitation spectra of the compounds depending on Sm3+ concentration is observed in 360–450 nm region, which includes the bands of transitions for both Eu3+ and Sm3+ ions. On luminescence excitation in the band of maximal absorption of Sm3+ ion (λeх = 404 nm), luminescence intensity of cooperatively doped La0.925Eu0.05Sm0.025(BO2)3 and La0.925Eu0.05Sm0.025BO3 increases, which can be explained by the possibility of efficient transfer of absorbed energy from Sm3+ to Eu3+ ion.
Synthesis of Fe-ZIF and Adsorption of Zinc and Copper Ions on Its Surface
Authors: Vashurin A. S. , Karaseva A. A. , Filippov D. V.
Published: April 2024

A method for the synthesis of Fe(III)-based zeolite imidazolate framework at various metal to linker ratios was proposed. The resulting material was used as an adsorbent for zinc(II) and copper(II) ions. It was shown that the materials were composed of hexagonal particles and represented a microheterogeneous system with an average particle size of 0.05–0.1 μm. The isotherms of nitrogen adsorption in the pores of Fe-ZIF were measured. By processing of the isotherms, porous structure parameters for the samples were found. The adsorption of Cu2+ and Zn2+ ions from aqueous solutions at 298.15 K was studied and high degrees of metal extraction was demonstrated. The adsorption of copper and zinc ions was spontaneous in all cases. The highest coverages of the surface active sites were 0.96 and 0.71 for copper and zinc, respectively. The adsorption in the bulk of energetically homogeneous porous adsorbent and predominance of micropores in iron(III) 2-ethylimidazolate structure were established.
Boron Difluoride β-Diketonates: Structure and Phosphorescence
Authors: Mirochnik A. G. , Fedorenko E. V. , Gerasimenko A. V.
Published: April 2024

Phosphorescence data on boron difluoride β-diketonates of various structure have been systematized. Nonplanar boron difluoride molecules are characterized by the inversion of the S1 and T2 levels, which promotes efficient population of triplet levels and intense phosphorescence or delayed fluorescence of crystals. Planar molecules are characterized by a classical sequence of singlet and triplet levels and a coplanar arrangement of antiparallel molecules, which contributes to excimer delayed fluorescence.
Synthesis of Solid Solutions of Barium Fluoride with Rare Earth Element Fluorides and Study of Their Up-Conversion Properties
Authors: Volchek A. A. , Kuznetsov S. V.
Published: April 2024

Solid solutions based on barium fluoride doped with rare earth element ions have been obtained by solid-phase synthesis. According to X-ray powder diffraction, the obtained samples have monophase fluorite structure. Increase in the concentration of rare earth element ions leads to decrease of crystal structure volume. Laser irradiation at 980 nm (radiation power of 1.2 W/cm2) produces luminescence in the visible spectral region. The presence of Yb3+ ion as sensitizer increases luminescence intensity for barium fluorides doped with Er3+ ions. Incorporation of Tm3+ ions into barium fluoride doped with Er3+ ions leads to decrease of total radiation intensity and the predominance of luminescence in the red spectral region. Color coordinates calculated from photoluminescence data by CIE 31 standard have been determined for the samples. The obtained materials of prescribed composition can transform infrared radiation into visible light.