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Russian Journal of Physical Chemistry B, Focus on Physics
Journal Prestige (SJR): 0.309

Citation Impact (citeScore): 1
Number of Followers: 0

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1990-7931 - ISSN (Online) 1990-7923
Published by Springer-Verlag

[2469 journals]

Kinetics of Decomposition of 1,1-Diamino-2,2-Dinitroethylene (Fox-7): 3.
Reaction in Solutions
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  Abstract: The kinetics of the thermal decomposition of 1,1-diamino-2,2-dinitroethylene (FOX-7) in solutions at temperatures of 180 to 240°C and a concentration of FOX-7 of ~1 wt % is studied by the gage and calorimetric methods. Chloro- and o-dichlorobenzene, nitrobenzene, and n-nitrotoluene are used as solvents. The dependence of the decomposition rate on the polarity of the solvent is shown, and the kinetic parameters of the reaction in the solution are determined. The data obtained are used to discuss the reaction mechanism and predict the rates of conversion of FOX-7 in the liquid and solid states.
  PubDate: 2022-02-01
Purification of Aqueous Solutions Containing Salts of Heavy Metals and
Ballast Ions
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  Abstract: The purification of aqueous solutions containing, together with the salts of heavy metals (lead and copper), sodium and calcium salts are studied. It is shown that cleaning with the use of AK-2 cation-exchange resin leads to the removal of only sodium and calcium salts from the solution. Cleaning with sorbents based on crown ethers also does not provide the complete removal of heavy metal ions from solutions. Almost the complete removal of all salts from solutions is achieved using a two-stage purification: first, the solutions are passed through the AK-2 resin and then treated with sorbents based on crown ethers.
  PubDate: 2022-02-01
On Non-stoichiometry and Partial Pressure of Oxygen in CdO thin Films
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  Abstract: We investigate theoretically the main aspects of the formation of cadmium oxide thin films (by metal evaporation) relative to non-stoichiometry and partial pressure of oxygen. As a matter of fact, mathematical relationships are obtained from that the Cd and CdO phases coexist when the corresponding chemical reaction begins. In fact, the Cd pressure (equal to the CdO one) is found to be proportional to the oxygen absolute temperature which, in turn, equals the Cd (or CdO) absolute temperature. Moreover, the electron drift-mobility in CdO is obtained as a function of the above temperature and as a function of the oxygen partial pressure. We emphasize that chemical kinetics is studied quantitatively by taking into account that a part of cadmium does not combine with oxygen, that is, stoichiometry vanishes. This means that, initially, CdO is still amorphous. This state occurs when the partial pressure of oxygen is smaller than the so-called optimum value of pressure which, by definition, is the value of the oxygen partial pressure at which the optical transmittance of CdO is maximum. These issues are investigated (by means of theoretical considerations) accurately in consistency with experimental data.
  PubDate: 2022-02-01
Effect of Impurity Gases on the Combustion of a Mechanically Activated Ni
+ Al Mixture
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  Abstract: In this study, we compare the combustion of nonactivated and mechanically activated Ni + Al mixtures. The combustion of compacted specimens and specimens of bulk density is studied. The combustion rate, relative elongation of samples, initial density and density of combustion products, and the microstructure and phase composition of the initial mixtures and reaction products are investigated. It is found that mechanical activation (MA) leads to a significant increase in the burning rate and elongation of the pressed samples, while the bulk density samples retain their length during combustion.
  PubDate: 2022-02-01
Influence of Spontaneous Fluctuations on the Emergence and Development of
Turbulence: 1. Calculation of the Contribution of Spontaneous Fluctuations
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  Abstract: The equations of multimoment hydrodynamics are used to study the process of distortion of regular flow modes in the problem of the flow around a sphere at rest. The influence on these distortions of spontaneous fluctuations, which are constantly present in the medium, regardless of the external effect, is investigated. After crossing the critical value of the Reynolds number, the stationary solution of the equations of multimoment hydrodynamics loses its stability. The loss of stability is accompanied by a qualitative change in the behavior of spontaneous fluctuations. Independence in their behavior disappears. The conservation laws force spontaneous fluctuations to adjust their behavior in time and space to the behavior of hydrodynamic values. In the absence of disordered perturbations, the fulfillment of conservation laws in a system that has lost stability is ensured by spontaneous fluctuations.
  PubDate: 2022-02-01
Study of the Mechanism and Kinetics of the Restoration of Hematites
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  Abstract: The effect of the reduction of hematite to magnetite on the strength characteristics of iron ore materials used in blast furnaces and shaft metallization furnaces is established. The mechanism and kinetics of the process of the reduction of hematite on samples of various sizes, taking into account the effect of the temperature and composition of the gas phase on it, are studied. The electrochemical behavior of samples from various hematites is considered, which makes it possible to judge the degree of defectiveness of the structure of the initial iron oxide. A dilatometric setup is used to study the change in the size of the hematite samples during the reduction heat treatment. Mineralogical and X-ray structural analyses are carried out, the results of which are used in carrying out kinetic analysis, which makes it possible to explain the main regularities and mechanisms of the processes during the reduction of hematite to magnetite. To describe such processes, equations for a contracting sphere are used. The values of the specific rates of the transition of hematite into magnetite at different contents of carbon monoxide in the atmosphere are analyzed. The results obtained are of interest and make it possible to develop technologies, which ensure the preservation of the initial magnetite in iron ore concentrates during its heat treatment, or to transfer the beginning of the reduction of hematite in blast furnaces and shaft metallization furnaces to the region of higher temperatures.
  PubDate: 2022-02-01
Water Activated by a Microwave Plasma Argon Jet as a Factor Stimulating
the Germination of Plant Seeds
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  Abstract: Using the new electrodeless microwave technology for generating plasma in an open atmosphere, solutions of hydrogen peroxide and nitrogen compounds are obtained from distilled water. The method is based on the activation of distilled water by a jet of thermal argon plasma of an electrodeless microwave discharge in air at atmospheric pressure. Plasma-activated water has a stimulating effect on seed germination and plant growth, which is much more effective than the effect of industrial hydrogen peroxide solutions with stabilizing additives.
  PubDate: 2022-02-01
Energy Capabilties of 5,5'-Azotetrazol-1,1'-Diol and Its Onium Salts as
Components of Solid Composite Propellants
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  Abstract: Dihydroxylammonium and dihydrazonium salts of 5,5'-azotetrazole-1,1'-diol and dihydroxylammonium salt of 5,5'-bistetrazole-1,1'-diol (TKX-50) are considered as potential components of propellants. The thermodynamic calculations carried out in this study show that some of the described compounds have a good potential for creating solid composite propellants with increased energy characteristics. The quantitative dependences of the energy parameters of the fuel on the properties of the studied compounds—the main filler, the proportion of aluminum in the composition, the type of binder, and the content of the latter—are established.
  PubDate: 2022-02-01
Interaction of Nitrogen Dioxide with Poly-p-Phenylene Terephthalamide
(Terlon)
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  Abstract: The study of the properties of polymer fibers is an urgent and important task for the creation of new, promising materials and modification of their properties under operating conditions. Using the methods of EPR and IR spectroscopy, thermoanalytical methods, and scanning electron microscopy, a comprehensive study of low-temperature oxidation in the air of poly-p-phenylene terephthalamide (terlon), previously nitrated with nitrogen oxides, and the mechanism of this process is presented. The phenylnitrite fragments of macromolecules formed during nitration are identified as an oxidation initiator. The polymer is destroyed as a result of the decomposition of N-nitrosoamides, N-nitro compounds, and N-nitrites: the products of terlon nitration. The main products of terlon nitration, esters and carboxylic acids, are determined by IR spectroscopy.
  PubDate: 2022-02-01
Growth of the Fungus Aspergillus niger on a Varnished Fabric in Different
Temperature and Humidity Conditions
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  Abstract: The effect of temperature and humidity conditions on the duration of the period preceding the increase in the mass of the Aspergillus niger fungus is studied during its growth on varnished-cambric insulation (the period of adaptation of the fungus to the material). It is found that temperature has a decisive effect on its duration. The effect of the relative air humidity is negligible. A simple analytical dependence is proposed that describes the change in the adaptation period over the entire studied temperature range. It is shown that in the temperature range most favorable for the growth of microorganisms, the value of the period is related to temperature by a dependence similar to the Arrhenius equation. The research results can be used in the development of methods for assessing and predicting the resistance of polymeric materials to the growth of fungi on them in various climatic conditions.
  PubDate: 2022-02-01
Study of the Adsorption Antioxidant Compound Malva on the BNNT(9,9-9): An
Investigation based on DFT Method
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  Abstract: In the present study, the interaction between Malva and Boron nitrid nanotube (9,9-9) [BNNT(9,9-9)] by DFT calculations has been investigated for the first time.The interaction effects of Malva with nanotube on the electronic properties, chemical shift tensors and natural charge have been also detected. NBO analysis suggested that the molecule Malva and the BNNT(9,9-9) play the role of both electron donor and acceptor at the complex BNNT(9,9-9)/Malva. The electronic spectra of the compound Malva and complex were calculated by TD-DFT method. Then, the possibility of the use of BNNT(9,9-9) for Malva delivery to the diseased cells has been established.
  PubDate: 2022-02-01
The Influence of Noble Metals on Thermoacoustic Vibrations and Boundaries
of the Region of a Negative Temperature Coefficient During Combustion of
n-Pentane-Air Mixtures
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  Abstract: The specific features of the ignition of premixed stoichiometric n-pentane–air mixtures are studied in the region of the negative temperature coefficient (NTC) of the reaction rate in a static fast puffing reactor in the presence of metallic platinum and palladium. It is shown that thermoacoustic oscillations occur in the NTC region in the absence of noble metals. However, in the presence of a platinum catalyst, which reacts with oxygen at the flame temperature and generates catalytic centers that propagate into the volume by convection/diffusion, thermoacoustic ignition modes disappear. In other words, the catalytic surface of platinum eliminates a certain stage of the kinetic mechanism: probably, the stage of inhibition after the appearance of a cold flame, while the NTC phenomenon disappears. In the presence of a palladium catalytic surface that does not generate catalytic centers propagating into the volume, the NTC phenomenon is observed. The discovered patterns should be taken into account when numerically simulating this phenomenon in the presence of a platinum surface; i.e., an acceptable chemical mechanism should describe thermoacoustic oscillations in the NTC region; and exclusion of a certain stage of the kinetic mechanism (probably of a surface nature) should cause the disappearance of the NTC reaction regime in the presence of a platinum catalyst. The stage should include a surface reaction of an active combustion intermediate on the platinum surface. In this reaction, the more active intermediates are formed from the less active product.
  PubDate: 2022-02-01
Molecular Docking of Cyanine and Squarylium Dyes with NSP15
Endoribonuclease of the SARS-CoV-2 Coronavirus
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  Abstract: The ongoing spread of the COVID-19 coronavirus infection requires us to find new tools and methods for detecting and studying the infection and preventing morbidity (new analytical procedures and tests). With the aim of developing probes for the detection of SARS-CoV-2 coronavirus by modeling in silico (molecular docking), the noncovalent binding of cyanine and squarylium dyes with different molecular charges and different types of heterocyclic residues and substituents (42 compounds in total) with different variants of the NSP15 endoribonuclease of the SARS-CoV-2 coronavirus (COVID-19) of the original (wild) type and mutant types is studied. The interaction energies and spatial configurations of the dye molecules in complexes with NSP15 are determined. Some dyes with negative values of the total energy of the complex Etot are promising for further practical study as probes for coronavirus.
  PubDate: 2022-02-01
Pitch-Based Carbon Fibers: Manufacturing Status and Modification of
Properties
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  Abstract: This paper analyzes the state of production of carbon fiber (CF) materials, including pitch-based CFs. It is shown that in Russia there is a significant potential for industrial production of pitch-based CFs. Considerable attention is paid to possible ways of modifying pitch-based CFs in order to improve their electrical properties. The efficiency of using gaseous bromine to reduce the electrical resistance of pitch-based CFs is shown. Based on the analysis of X-ray and Raman spectroscopy data, it is shown that a 7-fold decrease in electrical resistance during bromination is related to changes in the fiber structure.
  PubDate: 2022-02-01
Photochemical Properties of Octaphenyl-Substituted Erbium Phthalocyanine
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  Abstract: The spectral-kinetic characteristics of the singlet and triplet excited states of octaphenyl-substituted erbium phthalocyanine are established. It is shown that the compound has high values of the quantum yields of fluorescence (0.50) and singlet oxygen (0.43). The lifetimes of the excited singlet (4.9 ns) and triplet states (1.4 ms) are determined. The binding constant of phthalocyanine to bovine serum albumin (5.5 × 106 M–1) is calculated, indicating the effective binding of the test substance to albumin. The predominant accumulation of the dye in the cell cytoplasm on the model colon adenocarcinoma cell line (HCT116 cell line) is established. The localization of phthalocyanine in mitochondria and structures of the endoplasmic reticulum is established by confocal microscopy.
  PubDate: 2022-02-01
High-Temperature Interaction of Carbon Fibers with a Nickel Melt
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  Abstract: This paper investigates the features of the high-temperature interaction of carbon fibers with a nickel melt under the action of a short electric pulse and the formation of a multilayer graphite coating on the nickel surface. The saturation of a nickel droplet with carbon is achieved by diffusion on contact with carbon fibers. A multilayer graphite coating with a thickness of about 3 μm is formed on the nickel surface due to the segregation of carbon atoms dissolved in a molten nickel droplet.
  PubDate: 2022-02-01
Mechanical Properties of Composites Based on Polylactide and
Poly-3-Hydroxybutyrate with Rubbers
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  Abstract: The influence of elastomers—natural rubber (NR) and synthetic ethylene-propylene rubber (EPR)—on the morphology and physical and mechanical characteristics of composite materials based on polylactide (PLA) and poly-3-hydroxybutyrate (PHB), respectively, is studied. Differential scanning calorimetry shows differences in the patterns of changes in the thermophysical characteristics of the PLA—NR (with a rubber content of 5 to 15 wt %)—and PHB—synthetic EPR (10–30 wt %)—compositions. The melting point and the degree of crystallinity increase in the case of PLA and decrease in the experiment with PHB. The mechanical characteristics of the investigated compositions have similar dependences: with an increase in the content of rubbers, the relative elongation increases and the tensile strength and elastic modulus decrease.
  PubDate: 2022-02-01
Antioxidant Activity of Diatomic Phenols
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  Abstract: Nine compounds are studied for antioxidant activity, including those from the class of catecholamines containing 3,4-hydroxyphenyl (catechol) as a common structural fragment, which imparts antioxidant properties to the compounds in the reactions of hydrocarbon substrate oxidation. The antiradical activity is determined by the chemiluminescent method by the interception of peroxyl radicals in the model reaction of the initiated oxidation of ethylbenzene (RH). The mechanism of the inhibition of chain oxidation processes by diatomic phenol compounds is provided by the presence of two active hydroxy groups with a possible intramolecular hydrogen bond, leading to a weakening of the О–Н bond and a high rate constant of hydrogen abstraction in the reaction with peroxyl radicals (kinh). This reaction is dominant and determines the inhibitory activity of antioxidants in oxidation processes. The maximum inhibitory activity is shown by 3,5- and 3,6-di-tert-butylpyrocatechins, dopamine, and epicatechin.
  PubDate: 2022-02-01
Spontaneous Reactivation of OPC-Inhibited BChE Mutants: Modeling of
Mechanisms
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  Abstract: The mechanism of the reactivation reaction of the double mutant butyrylcholinesterase (BChE) double mutantAsn322Glu/Glu325Gly, inhibited by the organophosphorus compound (OPC) echothiophat is studied by molecular modeling methods. The ability of this mutant to spontaneously reactivate itself was previously shown experimentally. The energy profile of the reaction path calculated by the method of quantum mechanics/molecular mechanics (QM/MM) confirms that such a mechanism is possible. Molecular dynamics calculations with QM/MM potentials are used to investigate the proton transfer pathways and determine the protonated state of the glutamic acids in the active site of the double mutant. Possible ways of increasing its conformational stability are investigated by the methods of classical molecular dynamics.
  PubDate: 2022-02-01
Compressed Molecules and Enzymes
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  Abstract: Compression of molecules is a means to control their conformations and modify their ionization potentials and electron affinity by violation of atomic orbitals and their inter- and intra-molecular potentials. Compression induced modification of the vibrational frequencies increases the difference of zero point energies of isotopic molecules, which results to increasing isotope effects. By compression of single crystals the reaction trajectories of hydrogen atom transfer were identified. Compression is a means for the key, Life supporting enzymes, ATP synthase and DNA polymerase, to function as the molecular devices, overcoming high energy repulsive barrier and urging ATP and DNA synthesis. By using nuclear magnetic ions of magnesium, calcium, and zinc, catalyzing enzymatic ATP and DNA synthesis, the new radical pair mechanism is discovered. It is induced by compression of enzymatic sites and strongly, by 3–5 times, suppresses DNA synthesis and even more strongly, by 30–50 times, increases mortality of cancer cells. In this case compression of enzymatic sites dehydrates metal ions, stimulating electron transfer and switching on radical pair mechanism, responsible for the magnetic control of gene chemistry and magneto-biology.
  PubDate: 2022-02-01