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For the first time, the geometric and electronic structure of graphene oxide was calculated within the framework of the Hoffman and Ress models by the quantum-chemical method MNDO. Optimized structures of this compound are obtained. The acidic strength (pKa = 28 and pKa = 14) was theoretically estimated in the Hoffman and Ress model, respectively.

The ab initio 3.21G method was used to study the initiation mechanism of 2-methylpentene-1 under the action of a complex catalyst AlClCH - HO in heptane of stoichiometric composition 1:1:1:1. The energetics of this reaction is estimated, the values of its energy barrier and enthalpy are obtained.

Using the classical semi-empirical quantum-chemical method МNDO, for the first time the calculation of graphene oxide molecules was performed within the framework of the Nakajima-Matsuo and Lerf-Klinovsky models. The acidic strength of these models and the Hartree energy are theoretically estimated. It was found that the studied graphene oxides belong to dielectrics and to the class of intermediate Bronsted acids (pKa = 9-14).

The DFT method was used to perform a quantum-chemical calculation of graphene isomers from 7 hexagons. The energy of the forbidden zone of these models is estimated theoretically. It is shown that the energy of the forbidden band depends very significantly on the structure of the configuration of the isomers of the studied graphene.

The combined effect of modifying with cadmium and microalloying with rare-earth metals (REMs) on the formation of the structure and properties of the alloys based on electrical copper (copper hardened with fine CrB2 particles synthesized in a melt at the technologically available melting and casting temperatures) is studied. In the case of modifying a copper-based alloy with to 0.1 wt % cadmium, the grain refining of metallic matrix to an average grain size of 0.15–0.35 mm is found to take place. Moreover, the addition of 0.1 wt % REM is found to have a dual effect: the addition purifies grain boundaries of oxygen and sulfur, and Cu6Ce (Cu6La) intermetallic particles absorbed on the surface of CrB2 particles prevent their coarsening at the expense of coagulation. This fact makes the application of complex additions promising to improve the structure and properties of precipitation-hardened copper-based alloys for electrotechnical purposes.

In this work, we performed a quantum-chemical calculation of some epoxy molecules: 1,2-epoxy-butene, 1,2-epoxy-2-methylpropane, 1,2 epoxyethane by the density functional theory DFT. An optimized geometric and electronic structure of these compounds is obtained. It was found that the studied epoxides belong to the class of very weak СH-acids (pKa = 28-30).

In this paper, a quantum chemical calculation of some monomers: 4-methylpentene-1, 4-methylhexene-1, 4,4-dimethylpentene-1 by the density functional DFT method is performed. The optimized geometric and electronic structure of these compounds is obtained. It was found that the studied monomers belong to the class of very weak CH acids (pKa = 28).

This work continues a series of studies devoted to complex formation of ions of biogenic metals with the flavonoid dihydroquercetin (DHQ). The interaction of Со2+ ions with DHQ in aqueous solutions has been investigated. It has been found that, at different pH of a solution, complex compounds (CC) with different stoichiometry are formed; a variation of the pH value of a solution from 6.0 to 7.0 results in the formation of compounds (1)–(3) with the metal : flavonoid ligand ratio (Met : L) from 1 : 2 at рН 6.0 (1), through 2 : 3 at pH 6.4–6.7 (2), to 1 : 1 at рН 6.8–7.0 (3). By using the thermogravimetric method and the data of the elemental analysis, the most probable composition of the compounds with the determination of the amount of bound water has been proposed: [CoL2(H2O)4] for (1), [Co2L3(ОН)(H2O)4] for (2), and [CoL(ОН)(H2O)2] for (3). Conditions for the optimization of product yield in the complexation reaction of Со2+ ions with DHQ in an aqueous solution have been determined for compound (2): the рН value of solution 6.7; the reaction time 15 min; the temperature of the reaction solution 90°С; the molar ratio of the initial reagents DHQ : Со2+ 1 : 1.5; the initial concentration of DHQ 0.020 mol/L and that of Со2+ 0.030 mol/L; and the use of CoSO4 ⋅ 7H2O as a source of cobalt ions. The yield of the product is 81.8%.

For the first time, a quantum-chemical study of the mechanism of initiation of the cationic polymerization monomer of p-methylstyrene in the presence of a complex catalyst of aluminum chloride - hydrochloric acid in toluene with a stoichiometric composition of 1:1:1 by the ab initio method with the reaction coordinate RC1-H20 was performed. The reaction is exothermic . The activation energy of the reaction is 14 kJ/mol, and the thermal effect is -110 kJ/mol.

Dispersion of lead during smelting wrought aluminum alloys of the Al–Cu–Mg system with Pb additives and coarsening of lead-bearing phase particles during casting have a significant effect on ingot structure formation. The possibility of controlling these processes during preparation of lead-bearing aluminum alloys in a transport ladle due to melt modification with surface-active tin and electromagnetic mixing during input of briquetted master alloy containing wt.%: 50 Al, 45 Pb, 5 Cu is investigated. Optimum parameters for mixing melt providing effective dispersion of lead and its uniform distribution within the volume of melt are established.

In this work, we performed a quantum chemical calculation of cyclohexeneoxide and cyclopentenoxide using the method of density functional DFT. An optimized geometric and electronic structure of these compounds is obtained. It was established that the studied oxides belong to the class of very weak CH-acids (pKa = 28-30).

To raise the efficacy and the selectivity of known medicinal substances (MS), methods have recently been developed to create systems for their directed transport in the body using various carriers. The problem of decreasing the toxicity and increasing the selectivity of antitumor MSs is particularly relevant. In recent years, studies are underway for the development of conjugates of MSs and the natural polymers, in particular, the non-starch polysaccharides, many of which manifest antitumor and immunomodulatory properties. Owing to the unique combination of physicochemical and biological properties, arabinogalactan from larch wood (AG) is one of the most promising tools for the development of complex preparations with elevated bioavailability and reduced toxicity. The aim of the present work is to obtain mechanocomposites of cyclophosphamide (CPA) with the initial arabinogalactan (molecular mass 16 645 Da) and its fragments (molecular mass 8380 Da) and to study their physicochemical properties. According to IR and 13С, 15N and 31Р NMR spectroscopy, long-term mechanochemical treatment does not lead to a change in chemical composition of CPA molecules, only the formation of hydrogen bonds NH···OH is observed. The data on X-ray analysis, IR and multinuclear NMR spectroscopy show that, with a weight ratio of 1 : 5 and 1 : 10, disordering of CPA crystallographic structure and its molecular dispersion without chemical interaction of the components occur in the matrix of the polysaccharide with mechanical treatment of mixtures of CPA–AG over 4–12 hours.

Chemical composition of a phenolic complex of the Siberian spruce bark (Picea obovata Ledeb.) and a structure of oligomeric phenolic compounds composing the bark were studied. The samples of the spruce bark were collected in the vicinity of Lake Baikal in September 2015. Extractive substances were recovered from the crushed bark by extraction with ethyl acetate at the boiling point of the solvent for 4 h. The resinous substances were extracted from the ethyl acetate extracts with hexane by infusion for three days. The samples of bark after extraction with ethyl acetate were dried from solvent residues, and then water-soluble substances were isolated by extraction with distilled water at 90°C for 4 h. The yields of the extractive substances extracted with ethyl acetate and water from the spruce bark on absolutely dry matter were 3.4 and 6.9%, respectively. The relative percentage content of phenolic compounds in the ethyl acetate extract of the spruce bark was 42.4%. The ethyl acetate extract of a spruce bark, pretreated with hexane, was fractionated on a silica gel column using a mixture of chloroform–acetone as the eluent with an increase in the fraction of the latter (from 0 to 100%). The content of monomeric and oligomeric, polymeric phenolic compounds in the extract was determined. Based on the data of 1Н and 13C NMR spectroscopy, it was established that the flavonoid dihydroquercetin and stilbene glycosides isorhapontin and astringin were the main monomeric phenolic extractive substances of Siberian spruce bark. It was shown that the structure of oligomeric phenolic compounds of the spruce bark includes structural fragments of stilbene glycosides, mainly monomeric blocks with the structure of isorhapontin and astringin.

Currently, existing methods for evaluating the network performance of packet-switched networks are based on monitoring the excess of the values of network performance indicators of predetermined threshold values. At the same time, maximum, minimum and average values of indicators are widely used. In such operations, it is not taken into account that if the values of the indicators are in the range of permissible values, then the quality of the network connection is considered acceptable. It is most advisable to take into account the magnitude of the deviation of the indicator values from the areas of permissible values and the duration of such deviations. In this case, the deviation value will characterize the amount of network performance degradation, and the duration of the deviation will characterize the duration of the performance degradation. The network performance assessment thus formed will closely characterize the perception of the quality of the communication service by the user of the communication service. This article focuses on the development of such network performance metrics.

The urgency of developing the technology for obtaining the dihydroquercetin-zinc complex is due to the high antiradical, antioxidant, antiviral activity and wound healing effects of the original pharmaceutical composition developed on its basis. The study aims to optimize the complexation of dihydroquercetin (DHQ) with Zn2+ ions in aqueous solution and to develop a technological scheme for preparation of the complex. Previously, we have determined the reaction parameters for the laboratory scheme for preparing the complex. A tenfold increase in the volume of the reaction solution (from 50 to 500 mL) has led to a decrease in the yield of the product. The task was to correct some reaction parameters for increasing the yield of the complex. It has been found that the increase in the reaction time (from 15 to 240 min) and the DHQ concentration in the reaction solution (from 0.05 to 0.1 M), while maintaining the previously optimized reaction parameters (the molar ratio Zn2+: DKB = 2: 1, pH 5.6), leads to an increase in the yield of the complex from 12 to 84%. Correspondence between the structures of the complex and the compound previously obtained in small volumes has been confirmed by the data of IR, 13C and 1H NMR spectroscopy and elemental analysis. The study will contribute to the more intensive use of extractive substances of larch wood to create new drugs that have antioxidant properties intended for the treatment of various diseases.

The samples of Gmelin larch (Larix gmelinii (Rupr.) Rupr.) gum, selected from a variety of trees and from different parts of the tree in vicinity of Ulan-Ude (Buryatia), were investigated with GPC, IR, quantitative NMR 13C spectroscopy and spectrophotometry methods. The samples were dissolved in distilled water at room temperature. The mechanical impurities were filtered, the transparent solutions were evaporated to dryness, and the dry residues were purified by reprecipitation from water to ethanol. The content of mechanical impurities was 0.1–4.8% of the mass of absolutely dry gum. Aqueous solutions of gum were weakly acidic, as well as arabinogalactan (AG) isolated from wood of Siberian and Gmelin larches. It is established that Gmelin larch gum is a high purity arabinogalactan (~99%) with minor impurities of flavonoids, tannins and mineral substances. Molecular-mass characteristics and monosaccharide composition of Gmelin larch gum arabinogalactan is similar to arabinogalactan obtained from wood of all previously studied species of larch growing in Siberia and the Far East. The data suggest recommending Gmelin larch gum for application in medicine and the veterinary, food and cosmetic industries.

The dynamic problems of the theory of combustion and explosion are classified from the point of view of competition of the characteristic times of bulk chemical reaction, frontal combustion, heat transfer, gas flow from the vessel, compression (motion of the piston), and heating (cooling) rate. We consider dynamic similarity criteria such as the ratio of the characteristic times in problems of classical thermal explosion, dynamic thermal explosion, flammability limits, combustion in communicating vessels, competition of frontal and volumetric combustion, autoignition by adiabatic compression, competition of frontal combustion and piston motion, as well as compound similarity criteria (such as functions of simple dynamic similarity criteria). The problem of autoignition of a mixture by compression is considered, and a method for obtaining an analytical solution of the problem and an algorithm for the approximate solution based on a special differential criterion are proposed.

The antioxidant activity of dihydroquercetin (DHQ) complexes with zinc, copper(II) and calcium was studied in vitro in blood plasma of healthy donors. The state of lipid peroxidation (LPO) in blood plasma was assessed by the content of malondialdehyde (MDA), diene (DC) and triene (TC) conjugates. The effect of DHQ and the complexes on the activity of the catalase enzyme in blood plasma was determined. It was found that DHQ complex with zinc ion reduces the MDA content in blood plasma by 14.9% compared with the control, which is twice as high as for DHQ (7.5%). The corresponding parameters of DHQ complexes with copper(II) and calcium ions were 11.2 and 3.7%, respectively. The effect of the complexes on the decrease in the DC and TC content in blood plasma compared with the control is comparable with the corresponding parameters for DHQ. The DHQ complex with zinc ion increases the catalase activity by 1.5% compared with DHQ. The complexes containing copper(II) and calcium ions increase the catalase activity no more than DHQ.

The distribution of air oxygen atoms in the oxidation products of rich mixtures of syngas with air in flame and the under autoignition conditions at constant volume has been investigated by numerical simulation using the tracer method. It has been found that in rich mixtures, the oxidation of hydrogen and carbon oxide has a stepwise nature, which is clearly visible in the profiles of the rates of production of H2O and CO2. The observed stepwise nature inevitably results in the heat-release rate occurring in steps. The reaction pathways and the role of the oxygen atom of the CO molecule in the heat release in these flames has been investigated.

Fuel-rich laminar adiabatic flames of premixed dimethyl ether/air mixtures at a high initial temperature and atmospheric pressure have been studied by numerical simulation and sensitivity analysis. These flames, having two heat release zones, are of great interest as an unusual and little-studied subject. We have investigated the chemical processes occurring in the two zones and analysed the mechanism of heat release in the flame. It has been found that the key reactions that have a significant influence on the flame speed are those involving dimethyl ether and the products of its incomplete oxidation. Calculation of the heat release rate confirms the presence of two heat release zones in the flame. A comparison of the reactions making a major contribution to the heat release with those significantly affecting the flame speed indicates that the main factor determining the flame speed is the formation of hydroxyls, rather than heat release. Analysis of the flame speed sensitivity shows that in the case of ...

Physicomechanical and casting properties are studied for high-phosphorus irons used in the assembly of aluminum electrolyzer baked anodes in RUSAL enterprises compared with gray cast iron containing a minimum amount of phosphorus and sulfur. It is shown that iron primary crystallization under conditions approaching pouring production parameters and iron cooling in the nipple – cast iron – carbon anode contact assembly proceeds with significant supercooling that causes the formation of a pearlite matrix in the cast iron structure with increased hardness. Iron with a lower carbon equivalent exhibiting high hardness has a better elasticity modulus and strength values. The presence of ternary phosphide eutectic within the iron structure with a high phosphorus content reduces the breaking strength considerably at high anode operating temperatures and this may be a reason for cast iron loss of strength and anode separation at the end of an operating cycle leading the electrolyzer stoppage. Iron with the minimum phosphorus content exhibits strength exceeding by more than a factor of two that of high-phosphorus cast iron and also the least electrical resistance in the range up to 500–600°C. In addition, iron with a high phosphorus content has an anomalous change in linear thermal expansion coeffi cient (LTEC) in the range 600–810°C that may also lead to degradation of “soft” metal (anode at the end of an operating cycle). The results obtained are explained drawing on thermal analysis data and metallographic studies.

For communication services imposed on top of the disparate data transmission technologies assembled into a single system, the issues of comprehensive assessment of the quality of collaboration of such heterogeneous technologies within the framework of ensuring the quality of a unified communication service are not fully developed. The solution of this issue will ensure the overall quality of the service provided with the ability to localize the problem network segment and identify the causes of possible deterioration in the quality of the service provided.

To ensure the quality of service traffic transmission in a communication network, it is necessary to ensure that the values of quality indicators are within the allowable range of values. One of these indicators is the traffic transmission rate specified in the configuration of the user traffic profile. Monitoring the compliance of the actual profile of the user traffic with the profile specified in the configuration ensures maintaining the quality of the transmission of user traffic by maintaining the values of the quality indicators in a given range of values.

A differential system for measurement of gas temperature in gas turbine engines (GTE) using acoustic multi-vibrators was presented. Application of acoustic multi-vibrators improves the response time by three orders of magnitude compared to thermocouples. Combined use with a gas flow meter and a vibration sensor makes it possible to measure the low-frequency component of acoustic vibrations of flowing gases in a GTE’s combustion chamber. As an example, a calculation to determine the resonance frequency of a combustion chamber of a GTE was given.

We studied the chemical composition of the phenolic complex and the structure of oligomeric lignans in Siberian spruce (Picea obovata Ledeb.). We used the wood of Siberian spruce collected near the city of Irkutsk. The extractives were isolated from ground wood (particle size: 10–15 mm; humidity: 5.9%) by three-stage acetone extraction. The extract was separated by consecutive treatment with the solvents with increasing polarity: hexane, ethyl acetate and n-butanol. The main amount of phenolic compounds (lignans) was concentrated in the ethyl acetate fraction and it was 0.7% in absolutely dry wood (adw).

Samples of arabinogalactan (AG) were isolated by aqueous extraction from wood of different larch species (Larix sibirica Ledeb., Larix gmelinii (Rupr.) Rupr., Larix cajanderi Mayr., and Larix olgensis var. Koreana) and studied by HPLC, IR spectroscopy, and quantitative 13C NMR spectroscopy. The wood of the studied larch species was shown to contain significant amount of arabinogalactan (10–17% of the a.d.w. mass) and could be a source of its industrial production. The studied AG samples had similar structural and molecular-mass characteristics. This fact could facilitate the product standardization during its industrial production both from the wood of a single larch species and from mixed raw materials.

The problem of the steady-state turbulent flow of an incompressible fluid in the clearance between two coaxial infinite circular cylinders of radii R1 and R2, caused by the rotation of the inner cylinder of radius R1 under the conditions where the outer cylinder of radius R2 is immovable, i.e., the problem of a Taylor–Couette flow, was solved numerically within the framework of the model of a near-wall anisotropic turbulence with regard for the action of the centrifugal forces on the near-wall vortex structures determining the character of the flow between the cylinders. The profiles of the angular velocities of the fluid flowing along the radius of the clearance between the cylinders in the regime of completely developed turbulence were determined by numerical integration of the equation of motion of this fluid. The results of calculations of the flow between the cylinders at R1/R2 = 0.716 and Re = 105, 106, and 2·106 were compared with known solutions of the problem being considered and corresponding experimental data.

The propagation of fuel-rich hydrogen–air flames with added ethanol has been studied using numerical methods. It has been shown that the inhibition by ethanol is less effective compared to propane and propylene. The addition of ethanol leads to the effect of superequilibrium temperatures, but it takes place only at ethanol concentrations above a certain value. At the flammability limit of fuel-rich mixtures of hydrogen, ethanol, and air, determined by the Le Chatelier rule, the estimated maximum flame temperature is constant. The exception is mixtures with a small addition of ethanol.

The optimum parameters for the process of extraction of the dihydroquercetin (DHQ) isomer with the greatest antioxidant activity were identified. Use of ethyl acetate as extractant in this process was found to have clear advantages over other industrial solvents. An optimum method of extracting DHQ from larch wood with a large enantiomer excess was proposed. The method was developed and the quantitative content of the (+)-2R,3R isomer of DHQ extracted from wood of Larix sibirica Ledeb. was assayed.

Currently, communication networks provide a fairly large number of services to the end user. At the same time, each service has its own set of performance indicators for the network infrastructure, which determine the quality of the provision of this particular service. It should be noted that the quality of the provision of different communication services can be influenced by both different and the same quality indicators of the network infrastructure. At the same time, the common for some services indicators of the quality of the network infrastructure may have for each service different permissible ranges of values and be related or depend on the values of other indicators of the quality of the network infrastructure. Such complex relationships between the quality of network services and the quality indicators of the network infrastructure make individual monitoring of the values of the quality indicators of the network infrastructure not always advisable, because such monitoring algorithms have a high degree of branching due to a large number of conditions. In this case, it is most expedient to form for each service from the quality indicators of the network infrastructure some evaluation function, the output of which values beyond the allowable range will indicate degradation of the quality of a particular service and define a set of quality indicators for the network infrastructure for their further detailed control.

We considered the communication network as a complex object with large set of quality indicators. The performance of the network can relate to different levels of the network hierarchy and take into account the provision of various service functions. In order to maintain the value of the network at the appropriate level, it is necessary to have certain aggregated network performance indicators. To solve the effective monitoring problem, it is necessary to develop methods for network operation analyzing, taking into account all possible factors that affect the network operation and the formation of appropriate complex indicators on their basis. It has offered an effective network monitoring criterion.

Biocomposites were obtained from larch wood by mechano-chemical treatment of the samples of antiviral drugs arbidol and rimantadine with arabinogalactan, their physical and biological properties were investigated. It has been shown that the dose of introduced drugs can be reduced significantly while maintaining adequate levels of antiviral activity of unmodified drugs. Antiviral activity of complex drug dihydroquercetin with arabinogalactan has been investigated. Qualitative and quantitative composition of dihydroquercetin isomers have been investigated.

The structures of zinc (2), copper(II) (3), and calcium (4) complexes with trans-2R,3R-dihydroquercetin (1) have been elucidated by IR, 2D NMR, mass spectrometry DART techniques, term gravimetric analysis using data from elemental and microscopic energy dispersive X-ray analyses. The redox properties of complexes 2–4 were studied by cyclic voltammetry

The combustion chemistry of formaldehyde in fuel-rich flames has been studied by numerical modeling and sensitivity analysis. It has been shown that the wide flammability limits of CH2O/air mixtures are due to features of the combustion chemistry of formaldehyde at high equivalence ratios rather than to the superadiabatic temperature effect. In this case, the thermal decomposition reaction of hydrogen peroxide H2O2 plays a key role in the conventional branching reactions.

Two modular Cherenkov detectors FFD and T0 are developed for MPD and BM@N projects at LHEP/JINR for study of Au + Au collisions. The aim of the detectors is production of a start signal for a TOF detector and an effective L0 trigger for the collisions. The detector module design, characteristics, and results of tests with a deuteron beam are discussed. The time resolution of the modules for a single high energy photon or charged hadron is σt ≈ 21–31 ps and it depends on method and electronics used.