bluuebunny/crossref_metadata_2025 huggingface dataset:
FEATURES OF MECHANISM OF GAS-LIQUID POLYAMIDATION IN FOAMY HYDRODYNAMIC MODE
Authors: Nikiforov Vladimir A. , Laguseva Elena I. , Pankratov Evgeny A. , Zhokhov Ilya S.
Published: May 2020

The brief characteristics of the reaction system of pilot production of fatty-aromatic polyamides based on aliphatic diamines (acylated monomers) and dicarboxylic acid dichloroanhydrides (acylating monomers) by the method of gas-liquid polycondensation in a highly turbulized foamy hydrodynamic mode are described. Technological scheme and rational instrumentation of the technology of polyterephthalamides, the reactor unit (reactor-fibridator), which includes a two-stage reaction chamber and a gas phase generating chamber coaxially located under it, chemistry and operating principle of the facility are shown. The method combines the chemical processes of polyamidation with the physical processes of the reaction molding of polyamide fibrids or gas-structural elements used in the technology of gas-filled plastics. The reaction system of the method includes three structural units: a liquid phase (aqueous alkaline solution of aliphatic, cycloaliphatic and fatty-aromatic diamines), a gas phase (superheated vapours of aromatic and aliphatic dicarboxylic acid dichloroanhydrides, dispersed in a dynamic airflow or inert gas) and an interface (gas-liquid interface). Gas-liquid polyamidation is accompanied by phase formation: the reaction system during the process becomes three-phase system – the swollen polymer forms a solid mobile phase (target product), which acts as a foamy mode stabilizer, which allows technological process to proceed at optimal linear gas phase rates of 30–35 m/s (unlike classical two-phase foamy mode – 4 m/s). A polyamidation mechanism at the liquid-gas interface is proposed, which includes two versions of the process (adsorption and condensation) depending on the ratio of the temperature characteristics of the acylated monomer and the liquid phase carrying the acylating monomer. Analysis of the proposed versions of the mechanism allows you to make an engineering decision on the expediency of organizing a cycle in the liquid phase. Possible criteria for predicting the versions of the mechanism and examples of reaction systems with condensation and absorption versions of polyamidation are given.
CALCULATION METHOD OF IMPEDANCE MODULE FOR CORROSION MONITORING OF SURFACE STATE OF CHROMONICKEL STEELS
Authors: Vinogradova Svetlana S. , Akhmetova Anna N. , Tazieva Ramilya F.
Published: May 2020

In discussed issue the additional criterion for chromium-nickel steels surface state assessment is proposed. It is used in periodic potentiostatic regime of stainless steels surface state monitoring under the condition of pitting corrosion origin. Electrochemical investigations were carried out with pitting corrosion resistant austenitic (12Х18Н10Т) and austenitic-ferritic chromium-nickel steels 10Х17Н13М2Т in chloride solutions of 0.1 mol/L NaCl and 0.5 mol/l NaCl with the additional oxidant K2Cr2O7. Polarization curves were recorded under potentiostatic mode of polarization in the electrochemical three-electrode cell using the ZIVE SP2 workstation and a personal computer. The fast Fourier transformation method was used for conducting the spectral analysis, as this method is more effective in terms of the algorithmic complexity when processing a large amount of the initial data. It is established that scalar impedance angular coefficient shows the current oscillation frequencies change concerned with the pitting occurrence and passivation process. The scalar impedance angular coefficient allows to estimate the pitting corrosion evaluation processes boundaries: passivity; metal dissolution due to the development of metastable pittings; the metastable nucleation and passivation processes concurred with the stable pitting development. The algorithm based on the statistical method of spectral analyses for scalar impedance angular coefficient calculation is developed. It is established that the decrease in passive film total resistance corresponds to the breakdown process and first metastable, and then stable local surface destructions that reflect on the higher the scalar impedance angular coefficient value. The boundary values of an additional criterion for surface state assessment were proposed, on the basis of which an interval scale was constructed to determine the current state of the surface of chromium-nickel steels. It is shown that the boundary values of the scalar impedance angular coefficient correspond to the metallographic studies of investigated steels.
FOAMS STABILIZATION BY HYDROPHOBIZED OXIDES OF VARIOUS CHEMICAL NATURE
Authors: Vilkova Natalya G. , Mishina Svetlana I. , Deputatov Evgeniy D.
Published: May 2020

The properties of foams stabilized by hydrophobized titanium oxide and silica are studied. It was shown that when hexylamine was added to silica suspensions (in an amount of ≥ 10 mmol/l), the values of the hydrogen index corresponded to the alkaline region. Moreover, the stability of such foams increases with the increasing concentration of hexylamine and an increase in the relative degree of hydrophobization to ng = 2.75 mmol/g. However, rapid destruction of disperse systems is possible when a certain degree of hydrophobization is achieved (for example, ng≥3 in aerosil suspensions), which is due to aggregation of particles in the initial suspension. The dependence of the lifetime of these dispersed systems on the hydrogen index (pH) is shown. The most stable disperse systems were formed at the pH value of 5, which is close to the isoelectric point of the oxide. Foams obtained from the suspension of the composition: 20% titanium oxide + 76.6 mmol/l hexylamine remained stable for four days or more at pH = 5 and a change in the relative hydrophobicity of the surface (ng) from 0.383 to 1.27 mmol/g. With a significant increase in the degree of hydrophobization of the surface to 4.6 mmol/g and the same pH value, foaming was insignificant (the layer height (h) was 0.2 cm) and life time t≈10 sec.  Probably fixing the particles at the liquid-gas interface is an irreversible process only when a certain degree of hydrophobicity is achieved. To explain the possible causes of change stability of the foam containing the titanium dioxide from the pH we have investigated the distribution of particles according to their sizes by the method of sedimentation analysis. It was found that at pH=10 the fractional composition of the suspension with an average radius of 3 µm was equal to 50%, at the same time the maximum radius was 21 µm; the value of the wetting angle of the particles was equal to 40.8º. In an acidic medium (pH=2-3) and at pH=5, the fraction content with an average particle radius of 5 µm was 29% and 30%, respectively. However, low (14.7º) values of the wetting angle at pH=2 can cause low stability of foams in an acidic environment. Highly stable foams were obtained by changing the viscosity of the dispersion medium in suspensions of hydrophobized titanium oxide. When adding glycerol to the suspension composition: 9.0% titanium dioxide + 0.7% hexylamine, pH=9, gel foam was obtained, which was not destroyed within 10 days. However, in an acidic medium with the addition of the same amount of glycerol, the formation of a stable dispersed system was not observed.
CHANGE IN THERMODYNAMIC CHARACTERISTICS OF HYDRATION OF CARBOXYL FIBER SORBENT IN EXCHANGE OF MAGNESIUM AND CALCIUM CATION
Authors: Peregudov Yuriy S. , Niftaliev Sabukhi I. , Timkova Anna V. , Bondareva Larisa P. , Astapov Aleksey V.
Published: May 2020

The relationship between the characteristics of hydration and the selectivity of the fibrous carboxyl sorbent is established. Using the isopiestic method and thermal analysis, the hydration of the carboxyl fiber ion exchanger VION KN-1 in sodium, calcium and magnesium forms was studied. The quantity of absorbed water was determined, including the ratio of kinetically unequal water in the sorbent phase. The amount of water absorbed form of magnesium ion exchanger is greater than calcium, the molar proportion of water distribution varying in the degree of hydration of the magnesium and calcium forms fibers substantially equally. The changes in Gibbs energy of hydration and enthalpy of dehydration of ion-exchange fiber are calculated. The increase in Gibbs energy is due to the absorption of near- hydration water, and water farthest hydration is adsorbed at a constant value of the energy. Its highest values are determined for the magnesium form of the sorbent, and the least-for calcium, which corresponds to the ratio of the absorbed solvent of both forms in the first step of hydration. The exchange isotherms of calcium and magnesium ions on the sodium form of VION KN-1 fiber were obtained. The Gibbs energy of solvent interface transfer was calculated, which represents the difference between the Gibbs energies of ion exchange sorption and the direct exchange of cations, and describes the contribution of the change in sorbent hydration during the transition from one ionic form to another. It is found that the selectivity of extractable fiber ion exchanger to metal cations depending on the change in the sorbent during the hydration of ion exchange, which is energetically favorable process and promotes ion-exchange sorption. Carboxyl cation exchanger is more selective for magnesium ions than calcium ions, as confirmed by phase transfer energy high values solvent and less water released during the transition from the sodium form to the magnesium than during the transition to the calcium.
SYNTHESIS AND STRUCTURE OF ORGANYLTRIPHENYLPHOSPHONIUM DICYANOARGENTATES: [Ph3P(CH2)3PPh3]2+ [Ag(CN)2]– [Br]– AND [Ph3PR]+ [Ag(CN)2]–, R = CH2CH2OH, CH2C6H4F-4
Authors: Sharutin Vladimir V. , Sharutina Olga K. , Popkova Marina A. , Danilina Elena I.
Published: May 2020

The reaction of potassium dicyanoargentate with organyltriphenylphosphonium bromides in an aqueous solution has led to synthesis of complexes [Ph3P(CH2)3PPh3]2+[Ag(CN)2]–[Br]– (1), [Ph3PR]+[Ag(CN)2]–, R = CH2CH2OH (2), CH2C6H4F-4 (3), whose structures have been characterized by X-ray diffraction analysis (XRD). It is known that the absorption range of cyano groups in IR spectra of organic and inorganic compounds is in the form of a narrow interval of 2200-2000 cm-1, which points at the absence of strong surroundings influence on vibrations of these bonds. The absorption bands in the range 1450-1435 cm-1 peculiar to the P-Ph bands that are present in the spectra of compounds 1, 2, 3 are apparent in the range 1437-1439 cm-1. The XRD data have been obtained at 293 K on a Bruker D8 QUEST automatic four-circle diffractometer: crystals 1 (C41H36AgBrN2P2, М 806.44, triclinic syngony, crystal size 0.72 × 0.37 × 0.3 mm), 2 (C22H20AgN2OP, M 467.24, triclinic syngony, crystal size 0.8 × 0.52 × 0.35 mm), 3 (C27H21AgFN2P, M 531.30, monoclinic syngony, crystal size 0.28 × 0.23 × 0.22 mm). According to the XRD data, crystals 1, 2, 3 contain organyltriphenylphosphonium cations and linear dicyanoargentate anions. Besides, bromide anions are observed in crystal 1. A characteristic feature of complexes with the [Ag(CN)2]− anions is their perspective utility for development of new nano- and liquid crystal systems. The organyltriphenylphosphonium cations have a distorted tetrahedral configuration: the CPC angles vary within the range 106.70(8)° - 113.37(9)°. In the [Ag(CN)2]−anions the CAgC angles equal 171.75(10)° – 178.37(8)°.
SYNTHESIS AND STRUCTURE OF (METHOXYMETHYL)TRIPHENYLPHOSPHONIIUM TRICHLORO(DIMETHYLSULFOXIDO)PLATINATE
Authors: Tkacheva Alena R. , Sharutina Olga K. , Sharutin Vladimir V.
Published: May 2020

(Methoxymethyl)triphenylphosphonium trichloro(dimethylsulfoxido)platinate [Ph3PCH2OCH3][PtCl3(dmso-S)] was synthesized by the reaction of hexachloroplatinic acid with (methoxymethyl)triphenylphosphonium chloride in dimethyl sulfoxide. During the reaction, Pt (IV) was reduced to Pt (II). The reactions are accompanied by the ligand exchange in anions with substitution of the S-coordinated dimethyl sulfoxide molecule for one of chlorine atoms. Slow evaporation of the solvent led to the formation of large orange crystals. The product structure was determined by XRDA. The structures were interpreted by the direct method. Positions and temperature parameters of non-hydrogen atoms were refined in isotropic and then in anisotropic approximations by the full-matrix LSM. The X-ray diffraction pattern of crystal I was carried out on a Bruker D8 QUEST diffractometer. According to the data of X-ray analysis the unit cell crystallographic parameters of compound I are [crystal system monoclinic, space group P21/c, M 686.90, a 14.48(2), b 14.48(2), c 19.99(3) Å]. The tetrahedral configuration of the (methoxymethyl)triphenylphosphonium cation approaches the ideal values (CPC angles are 108.5(2)°-110.3(2)°, bond lengths Р-С are slightly differ from each other). Platinum atoms in anions have square coordination (trans-arranged angles ClPtCl are 177.65(5)°, SPtCl are 178.88(6)°, cis-angles approach 90°). The bond lengths Pt–Cl are equal to 2.290(3)–2.314(3) Å, Pt–S are equal to 2.205(3) Å. The platinum atoms are coordinated by three chlorine atoms and dimethyl sulfoxide molecule in the anion. Dimethyl sulfoxide molecule is coordinated to the platinum atoms by sulfur atoms. The geometry of the coordinated dimethyl sulfoxide ligand [OSC and СSC angles, S−O bond] differs from the geometry of a free dimethyl sulfoxide molecule.
INFLUENCE OF BACKGROUND ELECTROLYTE AND SURFACE-ACTIVE SUBSTANCES ON EFFICIENCY OF ELECTRO-FLOTATION EXTRACTION OF HARDLY SOLUBLE EUROPIUM COMPOUNDS
Authors: Kolesnikov Artem V. , Tangalichev Roman D. , Berezin Nikolay B. , Mezhevich Zhanna V.
Published: May 2020

Europium and its compounds are widely used in high-tech processes of nuclear and hydrogen energy, electronics, medicine and other fields. In this work, the regularities of electroflotation extraction of hardly soluble europium compounds from model systems were obtained and analyzed. The aim of the work is to obtain data on the process of electroflotation extraction of hardly soluble europium (III) compounds from model systems with background electrolyte and the addition of surface-active substances, establishing optimal conditions for efficient extraction of hardly soluble europium (III) compounds. The research was conducted at room temperature (20 ± 2 °C) in a non- current electric flotator of periodic action, which is made in the form of a vertical column. The cross-sectional area of the electric flotator is 10 cm2, the volume of the treated solution is 500 ml, the height of the apparatus is 800 mm, and the sampling valve is located at a height of 40 mm from the electrode unit. The electrode unit consists of an insoluble anode made of ORTA (titanium with ruthenium oxide coating) and of a cathode made of stainless steel mesh (cell size 0.5 × 0.4 mm, wire thickness 0.3 mm). The mass concentration of europium (III) was determined by a mass-spectrometer with inductively coupled plasma of Termo Scientific brand. Determination of particle size and particle size distribution, surface charge of particles of the dispersed phase (ξ) were carried out using a Photocor Compact-Z laser particle analyzer. The efficiency of the process of extracting hardly soluble compounds of Eu3+ was evaluated by the degree of extraction α (%). The objects of study are colloid-dispersed systems of poorly soluble compounds of europium (III) in aqueous solutions in the presence of surface-active substances of various nature and background electrolytes. The initial aqueous solution contains: СEu3+ - 0.1 g/l, Cbackground electrolyte - 1 g/l, background salts: NaCl, NaNO3, Na2SO4; Csas - 5 mg/l. It has been shown that for each type of solution the efficiency of the electroflotation process is achieved at certain pH. It is established that the optimal conditions for the extraction of europium (III) compounds are: volume current density, Jv = 0.4 A/l; process duration 10 min. For nitrate background the degree of extraction is maximum at pH 10 - 11 and at the presence of an anionic surfactant additive in the solution (Оxy surfactant A1218). When extracting europium (III) compounds from a system with a sulphate background the best results were obtained at pH values of 8 and 10, as well as the addition of an anionic and, or cationic (Septa surfactant XEV70) surfactant. Chloride background showed the best conditions for the extraction of europium (III) at pH 7 with the addition of a non-ionic surfactant of PEO-1500 brand. The degree of extraction of europium is 98-99%.
"POLYHEDRAL CONTRACTION" OF TETRAMETHYLAMMONIUM CLOSO-CARBOUNDECABORATE UNDER ACTION OF TRIS(TRIPHENYLPHOSPHINE)RUTHENIUM DICHLORIDE
Authors: Konoplev Vitalii E. , Tachev Maxim V. , Ulyukina Elena A.
Published: May 2020

In this paper the objectives were not only to investigate new promising methods leading to a deep structural rearrangement of carboranes and metallacarboranes but also to try to fix, to isolate and to characterize the intermediates. At the same time considerable attention is paid to the so-called "anti-wade" clusters formed during the reactions, the electronic structure of which does not correspond to their actually observed geometry. It is shown that the interaction of 11-vertex monocarbon closo-carboundecaborane with tris(triphenylphosphine)ruthenium dichloride leads to a series of new metallacarborane complexes. For the first time it was possible to control the process of "polyhedral contraction" of carborane {CB10} → (RuCB10} → {RuCB9} → {RuCB8} → {RuCB6} on the example of ruthenium complex and also to confirm experimentally each stage of the whole process. As a result of the reaction clusters of classical type and electron-deficient isocloso-/hypercloso-rutenacarborans {RuCB8}, {RuCB9} with 2n skeletal electrons were isolated. It is found that the interaction of tetramethylammonium closo-carboundecaborate with tris(triphenylphosphine)ruthenium dichloride proceeds in several stages. The first intermediate 12-vertex cluster is formed by mixing the initial reagents under heterogeneous conditions (methanol-THF, K2CO3, triethylbenzylammonium chloride) at room temperature for 10 hours. When the resulting complex is stirred in a mixture of methanol-THF solvents for 7 days at 20 °C, its almost quantitative transition to 11-vertex rutenacarborane was observed. Further transformation with the formation of a 10-vertex isocloso-rutenacarborane occurs when the methanol solution of this complex is boiled for 15 minutes. When the complex is boiled in methanol for 8 hours we obtained another extraordinary metallacarborane belonging to the rare 8-vertex pileo-clusters with a boron vertex built over the triangular face.
EFFECT OF MECHANOCHEMICAL TREATMENT OF INGREDIENTS ON STRUCTURE AND PROPERTIES OF RUBBER MIXTURES AND RUBBERS ON BASIS ОF 1,4-CIS-POLYISOPRENE
Authors: Makarov Vladimir M. , Nikitina Elena L. , Solovyeva Olga Yu.
Published: May 2020

The effect of the mechanochemical treatment of components of the sulphurous vulcanizing group on the properties of rubber mixtures and rubbers on the basis of 1,4-cis-polyisopren, filled with carbon black N330, was investigated. The mechanochemical activation of the components was carried out by processing them in a device that is a reactor with magnetic elements and a coil of inductivity. When connecting the inductor to the electrical grid, the working elements are exposed to the magnetic field and began to move intensiocly way with the transfer of energy to powdered particles. The treatment of both individual components: zinc oxide, accelerators, and all components of the sulfur vulcanizing group leads to an increase in the rate and degree of structuring of rubber in the main vulcanization period and a decrease in the tendency of rubber to reverse in the postvulcanization stage. In this case the values of elasticity modules increase and mechanical losses in vulcanizates reduce as the temperature increases. Most of these changes in the properties of mixtures and rubbers are expressed in the processing of individual accelerators and together all components of the vulcanizing group. Storage of activated ingredients for 30 days does not lead to significant changes in the structure and properties of rubber mixtures and vulcanizates.
EFFECT OF DURATION OF OXYCHLORINATION ON DEGREE OF ACCESSIBILITY FOR CATALYSIS OF PLATINUM CENTERS OF PLATINUM-RHENIUM REFORMING CATALYST
Authors: Starostin Andrey G. , Khodyashev Nikolai B.
Published: May 2020

The work presents the results of a chemisorption analysis of a platinum-rhenium catalyst on an alumina support after regeneration and reduction with hydrogen. Adsorption-desorption diagrams were obtained by stepwise-pulsed chemisorption of carbon monoxide on reforming catalyst samples. With an increase in the number of carbon monoxide injections from 1 to 4, the catalyst sample is poisoned, and subsequent desorption peaks indicate the termination of the interaction. With an increase in the time of oxychlorination, the CO/Pt ratio in the carrier volume increases linearly. The effect of the oxychlorination process on the chemisorption of CO and the subsequent availability of platinum nanoparticles for catalysis has been shown. The absorption on freshly prepared platinum-rhenium catalyst samples reaches a CO/Pt molar ratio of about 0.4. The results show that the duration of oxychlorination for 16–20 h allows us to achieve the value of the ratio CO/Pt, which is in the range of 0.4-0.5. This indicates that the availability of platinum centers in its composition reaches the level of a fresh catalyst, and, on the other hand, taking into account a slight excess of this ratio, we can assume that some of the Re atoms participate in the absorption of CO molecules. The presence of finely dispersed platinum particles in the composition of the regenerated catalyst was confirmed by IR spectroscopy. The analysis of catalyst samples on an IR spectrometer in the frequency range of 1900-2200 cm-1 revealed a rather wide absorption band with a pronounced extremum at 2060 cm-1. In this frequency range, there is another, slightly pronounced extremum at 2149 cm-1. However, for samples with a short duration of oxychlorination, it did not appear. An absorption band with an extremum of 2060 cm-1 can be attributed to linear vibrations of adsorbed CO molecules on the surface of particles of metallic platinum.
PHYSICAL AND CHEMICAL STUDIES OF SLAG OF PRODUCTION OF LOW-CARBON FERROCHROME - COMPONENT OF HEAT-RESISTANT BINDER MATERIAL
Authors: Bazhirov Tynlybek S. , Dauletiyarov Muhtar S. , Bazhirov Nurlybek S. , Serikbayev Bolatzhan E. , Bazhirova Kamshat N.
Published: May 2020

The aim of the work is physicochemical studies of chemical and mineralogical composition of the slag from the production of low-carbon ferrochrome proposed to use as a component of heat-resistant binder. As a result of studies, it was found that the main crystal phase in the slag is calcium orthosilicate in the form of γ-Ca2SiO4 modification, which is also partially in the form of α-Ca2SiO4, and magnesian silicates in the form of forsterite Mg2SiО4. The main properties of the slag such as density, specific surface, dispersiveness, refractoriness are determined by the properties of the dominant mineral- calcium orthosilicate. Under conditions of slow cooling of the slag melt, the main mineral in the slag composition, i.e. calcium orthosilicate β-Ca2SiO4 passes into γ-Ca2SiO4 modification with increase in the volume of crystal lattice by ~ 12%, which leads to self-destruction and transition of the slag to a dust state. The results of studies of the specific surface, determination of the average particle size, the results of sieve analysis showed that the slag from the production of low-carbon ferrochrome is a finely dispersed gray powder with the following characteristics: the specific surface is 2955 cm2/g, the average particle size is 6.8 μm, the true density is 3.01 g/cm3, the bulk density is 739 kg/m3. When using the finely dispersed slag from the production of low-carbon ferrochrome as a component of composite binders, the energy-consuming process of its fine grinding can be eliminated. Currently, the slag from the production of low-carbon ferrochrome is practically not used as a secondary mineral raw material. However, the physicochemical properties of the minerals making up the slag allow to recommend it as a component for the manufacture of heat-resistant materials. The results of physical and chemical studies can be used to develop effective technologies for integrated processing of low-carbon ferrochrome slags.
EXPERIMENTAL AND MODEL EVALUATION OF DIFFUSION COEFFICIENTS OF BARIUM IN LIQUID GALLIUM AND LEAD
Authors: Zhuravlev Vladimir I. , Zhirkova Yuliya N. , Khorishko Boris A.
Published: May 2020

Gallium and lead are used as liquid cathodes to produce alloys of alkaline earth metals, including barium. Data on the diffusion coefficients of barium (DBa) in liquid metals obtained by anodic chronopotentiometry are very limited. In this paper, an experimental evaluation of DBa in liquid gallium and lead was carried out by a combined method. It is based on the joint processing of the measurement data of the cathode chronopotentiometry in the coordinates E–ln√τ and the equations of the isotherms of the potentials of the alloys of the E–lnXBa obtained under the same conditions. Measurements were carried out in the melt KCl– 26 mol % BaCl2, at temperatures from 953 to 1073 K. The basis for the calculation of DBa is the Sanda equation. The features of electrode processes on liquid metal cathodes in barium-containing chloride melts are taken into account. The values of stabilized residual current densities depending on the temperature are established. It is shown that at the beginning of the process of barium separation into alloys, the effect of joint potassium deposition is manifested, especially on the lead cathode. The contribution of barium current output is proposed to be estimated by the current selectivity index, which depends on the potential of the alloy. It is shown that the joint discharge of potassium and barium into alloys leads to an overestimation of dva on gallium and lead from 5 to 12%. The activation energies of barium diffusion in gallium and lead, respectively 20.7 and 16.2 kJ/mol, were calculated on the basis of the obtained temperature dependences of DBa. Calculations show that on liquid thallium, bismuth, antimony measurement of cathode chronopotentiograms for barium is impossible, because of significant potassium co-deposition. Based on the data on the structure of dilute alloys and thermodynamic characteristics of alkaline earth metals, the method of calculation of reduced radii of microgroups-diffusers in the Stokes – Einstein equation is proposed. The DMe values calculated using the reduced radii are in satisfactory agreement with the majority of experimental data. These facts confirm the validity of the model of collective diffusion of barium and other alkaline earth metals in alloys as part of microgroups by translational mechanism.
SYNTHESIS OF A NEURO-FUZZY MODEL OF RADICAL POLYMERIZATION PROCESS KINET-ICS
Authors: Lopatin Alexander G. , Vent Dmitriy P. , Brykov Bogdan A.
Published: May 2020

There was considered the kinetic scheme of the processes of methyl methacrylate and styrene polymers synthesis by the radical polymerization method. It is shown that the main difference in the above kinetic schemes is observed in the last stage of the reaction and lies in the mechanisms of breaking the polymer chain – by recombination for polystyrene and by disproportionation for polymethyl methacrylate. There were given the well-known mathematical models describing the kinetic scheme for the polymerization of methyl methacrylate and styrene and showing the dependence of the degree of monomer to polymer conversion on the time. It is shown that each of the presented models contains a large number of empirical constants, the values of which differ by orders of magnitude among different researchers, which greatly complicates the use of these models and often leads to confusion and incorrect results of simulation modeling. In addition, some of the known models do not take into account the phenomenon of auto-acceleration of the process - the gel effect inherent in the radical polymerization of styrene and, to a greater extent, methyl methacrylate. Thus, the necessity of developing a simpler in its structure adequate mathematical model of the processes under consideration based on the methods of neuro-fuzzy modeling was substantiated. The results of studying the rate of polymerization of methyl methacrylate and styrene in a laboratory reactor under different initial conditions were used as initial data in the development of a fuzzy model. With the help of an adaptive neuro-fuzzy system, there were obtained primary models of the Takagi-Sugeno type, after processing which, we obtained the final fuzzy model. The accuracy of the obtained model was verified by conducting a comparative analysis of the results of process simulation with different initial data and results obtained in a laboratory reactor. The good data convergence were shown and recommendations were given for using the model.
THERMODYNAMIC CHARACTERISTICS OF ACID-CORE REACTIONS INTERACTIONS IN THE WATER SOLUTION PIRIDOXAL-5'-PHOSPHATE
Authors: Lytkin Alexander I. , Krutova Olga N. , Krutova Ekaterina D. , Mokhova Yuliya V. , Tyunina Elena Yu.
Published: May 2020

As the object of the study, we selected 3-hydroxy-2-methyl-5-(phosphonic) methyl-4-pyridincarboxaldehyde (pyridoxal-5'-phosphate) which is one of the most important biologically active compounds. Direct calorimetric method was used to measure the thermal effects of interaction of the solution of pyridoxal-5'-phosphate with solutions of nitric acid and potassium hydroxide at 298.15K and ionic strength values of 0.5; 1.0 and 1.5 against the background of electrolyte-supporting potassium nitrate. The measurements were carried out in a calorimeter with an isothermal shell equipped with a 60 cm3 reaction vessel and electric calibration at T = 298.15K ± 0.01 К and P = 100.5± 0.7 kPa and automatic recording of the temperature-time curve. Relative measurement error for heats of dissolution of a standard substance was -0.1-0.3%. Close values of constant sequencing of pyridosal-5'-phosphate do not allow to distinguish such an area of pH where only one of the processes of step dissociation would occur. In this regard the total thermal effect of protonation of pyridoxal-5'-phosphate would be measured. Calculation of the equilibrium composition of the system took into account processes step dissociation and water dissociation was carried out according to the KEV program. The thermal effects of stepwise dissociation of pyridoxal-5'-phosphate are calculated using the universal HEAT program. Because, the thermal effects of dilution were measured in three concentration ranges of KNO3: 0.4-0.5;0.9-1.0; 1.4-1.5 mol /l, the number of experiments in each series was at least four. To calculate the confidence interval of the average value of DН Student's criterion was taken at a confidence interval of 0.95 The standard thermal effects of stepwise ionization of pyridoxal-5'-phosphate were found by extrapolation of experimentally obtained amounts of piridoxyxal-5'-phosphate to zero ion force of the solution.
SYNTHESIS OF RUTHENIUM (IV) OXIDE ON TANTALUM BY ATOMIC LAYER DEPOSITION
Authors: Gants Oksana Y. , Yudina Angelina D. , Zhirnova Valentina O. , Timonina Anna S. , Lyukshina Yulia I. , Akhmatova Anna A.
Published: May 2020

The results of synthesis of nanoscale films of ruthenium dioxide on tantalum are presented. The films were obtained by atomic layer deposition at the TFS 200 Beneq setup (production Finland). As precursors bis(ateltico-pentadienyl) ruthenium and oxygen were used. Nitrogen acted as an inert gas to purge the reaction chamber of precursor residues and reaction products. The synthesis was carried out in two stages: activation of the tantalum surface by hydroxyl groups and alternate supply of ruthenium and oxygen precursors to the reaction chamber under certain conditions. The main regularities of the process were revealed and the method of synthesis realization was proposed. It is shown that the synthesis result is influenced by the process parameters of the atomic layer deposition method. The main parameters affecting the process are the temperature in the reaction chamber and the precursor requiring heating, the time of the precursor intake and the time of nitrogen purging. Also, in the process of synthesis, such a parameter as "pause" is used-the temporary cessation of the supply of any reagents to the reaction chamber to increase the ratio of reacting molecules. The influence of each process parameter on the synthesis of thin films of ruthenium dioxide is substantiated and experimentally confirmed. It was concluded that the optimal deposition temperature of ruthenium dioxide is 220 °C. The optimum temperature of the heated precursor is 80 °C. The optimal time of the ruthenium precursor is 1 s, the time of the oxidizing agent is 10 s under the stated conditions. The optimal "pause" time is 3 s after the intake of bis (ethylcyclopentadienyl) ruthenium, and 5 s after the intake of oxygen. The presented method of synthesis of ruthenium dioxide will allow to obtain high-quality, uniform throughout the thickness of nanoscale films that can be used as an electrode in capacitors.
L-ARGININE DETERMINATION IN BIOLOGICALLY ACTIVE ADDITIVE BY VOLTAMMETRY
Authors: Popova Valentina A. , Ponomareva Maria N. , Korotkova Elena I.
Published: May 2020

This article reports about the electrochemical determination of L-arginine on a glassy carbon electrode in a dietary supplement using anodic differential pulse voltammetry. The exponential depense of the peak current on the square root of the scan rate (I/v1/2), the shifts of the potential to the negative area and linear correlation between peak potential and logarithm of the scan rate (lg(v)) confirms that electrooxidation of L-arginine is an irreversible process. Moreover, the criteria of Semerano equals 0.4 may indicate the process of electrooxidation without adsorption. The effect of pH, accumulation potential, accumulation time and scan rate was tested on electrochemical behavior of L-arginine. Working conditions for L-arginine determination in model media are following: pH 13; Eacc 0.3 V, tacc 30 s; v = 60 mV s-1. A linear dependence of L-arginine electrooxidation current on its concentration was observed at the 0.9 V in the range between 1.0∙10-4 and 10∙10-4 mol l-1. The detection limit was 1.34∙10-6 mol l-1. A comparative determination of L-arginine in dietary supplement was carried out by the voltammetric method and capillary electrophoresis. Thus, the determination of L-arginine in a dietary supplement on a glassy carbon electrode in NaOH solution (pH 13) was successfully carried out using anodic differential pulse voltammetry. The proposed method does not require sample preparation and allows to quickly determine L-arginine in dietary supplement.
IDENTIFICATION OF TRANSFORMATION FUNCTIONALIZED ARENES DIRECTIONS IN NATURAL ENVIRONMENT CONDITIONS
Authors: Lebedev Anton S. , Orlov Vladimir Yu.
Published: May 2020

The article discusses the evaluation of the aromatic compounds pathways transformations – widespread xenobiotics of aqueous systems. This issue has both theoretical (chemical lability in complex reaction systems) and applied (target designation for the development analytical methods) meaning. Benzoic, 4-hydroxybenzoic, 2-hydroxybenzoic, 2-chlorobenzoic acids, 4-hyd-roxybenzoic acid methyl ester, and salicylic ester of acetic acid were chosen as objects of investigation. They have been used in food, pharmaceutical, cosmetic industries as preservatives, in chemical industry and laboratory practice as starting materials for the synthesis of new organic compounds, in analytical chemistry as reagents, chromophores, and standards in calorimetric analysis. We used quantum chemical modeling mechanisms of abiotic and biodegradation of functionalized arenes as a research method. It has been shown that for the transformation of benzoic acid, including oxidative breaking of cycle, the most probable is the path through 2,3-di-hydroxybenzoic acid to 1,3-butadiene-1,1,4-tricarboxylic acid (the product of the intradiol oxidative breaking of the cycle). There is transformation path through 2,3-dihydroxybenzoic acid to 1,3-butadiene-1,1,4-tricarboxylic acid (product intradiol oxidative rupture of the cycle) realized for 2-hydroxybenzoic acid (compound itself and the products of the conversion of salicylic ester of acetic acid, 2-chlorobenzoic acid). Pathway is observed through 3,4-dihydroxybenzoic acid to 1,3-butadiene-1,2,4-tricarboxylic acid (the product of the intradiol oxidative break cycle) for 4-hydroxybenzoic acid (compound itself and the product of the conversion of 4-hydroxybenzoic acid methyl ester). As it follows from the above, the intraradiol path of the oxidative cycle breaking seems to be the most preferable. Accordingly, a preferential accumulation of the following substances should be expected as results of the samples transformation: 2- and 4-hydroxybenzoic acids, 2,3- and 3,4-dihydroxybenzoic acids, products of the radical oxidative breaking of the cycle and the results of their further transformation.
STRUCTURAL AND DYNAMIC CHANGES IN MIXED FORESTS OF BEECH AND FIR ON MT. GOČ
Authors: Obradović Snežana , Pantić Damjan , Medarević Milan , Šljukić Biljana , Pešić Biljana
Published: May 2020

The primary goal of this research was to analyze the structural, production and dynamic changes of theforests of beech and fir in permanent sample plots of Mt. Goč, excluded from regular management fora period of 35 years (1977–2011). The established principles of spontaneous development and selfregulatoryprocesses could have implications on the regular management in these forests located in thearea of Mt. Goč and other areas.The results of this research in the permanent sample plots indicate that the mixed forests of beech andfir have suffered a number of changes in terms of structure and production in the investigated period.Structural disruptions have been the result of a decrease in the share of small and medium-diametertrees, as well as an increase in the share of trees of large dimensions in the total number of trees. Thecurves of distribution have been moved to the right and in terms of shape they differ from the lines thatare typical of selection forests. A relatively large number of trees per hectare and the described distributionby diameter classes have resulted in the high values of basal area and stand volume. In addition,a high volume increment has also been recorded. The quality and incremental capacity of the standshave been reduced due to a significant share of old beech and fir trees. The accumulation of volumeslowed down the dynamics of stand development and hindered rejuvenation and recruitment, as thenecessary prerequisites for structural stability and functionality in selection forests.The observed trends of development in these forests in the sample plots clearly indicate that a structurallystable, socio-economically and ecologically valuable selection forest is possible to achieve only withan active and continuous implementation of a set of management procedures, which primarily refersto selection cutting. Self-regulatory processes that are allowed over time, as in the case of the analyzedsample plots, are increasingly distancing us from this goal.
ГРАДАЦИЈА СМРЧИНИХ ПОТКОРЊАКА НА ПОДРУЧЈУ ХАН ПИЈЕСКА
Authors: Станивуковић Зоран , Васиљевић Ранко
Published: May 2020

Рад се бави утврђивањем бројности смрчиних поткорњака (Ips typographus L., и Pityogeneschalcographus L.) и њиховом значају у појави сушења смрче, на подручју Хан Пијеска. Смрча наовом подручју има велики привредни и еколошки значај. Постављањем клопки са синтетизова-ним агрегационим феромонима успостављен је мониторинг наведених смрчиних поткорњака.Утврђена просјечна бројност по клопци обје врсте поткорњака је вишеструко виша од критичне усезони, карактеристична је за градацију и доводи до сушења значајнијих размјера.
ZELENI KORIDORI KAO ELEMENT URBANOG PLANIRANJA: POGLED IZ TREBINJA
Authors: Došenović Ljiljana , Trkulja Tanja , Marić Tijana
Published: May 2020

Rad istražuje mogućnost unapređenja kvaliteta života i prirodnog okruženja u procesu razvoja gradovaplaniranjem zelene infrastrukture na lokacijama napuštenih željezničkih koridora. Teoretsko istraživanjeobuhvata elaboraciju definicije, funkcije i podjele zelenih koridora sa naglašavanjem njihovih ekoloških,socio-ekonomskih i zdravstvenih beneficija kako za pojedinca tako i zajednicu, koje se prije svega odnosena podsticanje očuvanja kulturnog i prirodnog nasljeđa, promociju zdravog načina života i održivogekološkog turizma. Preispitani su osnovni aspekti razvojnih procesa gradova, a poseban akcenat je stavljenna urbanu matricu Trebinja. U posljednjoj etapi razvojnih tokova Trebinje je pod snažnim uticajemopštih društveno-političkih promjena koje su ga postavile u sasvim drugi kontekst prostorno-funkcionalnihrelacija u odnosu na okruženje. Uspostavljanjem snažnih državnih granica Bosne i Hercegovine iHrvatske je onemogućen istorijski kontinuitet razvoja grada oslonjen na saobraćaje, trgovačke i kulturneveze sa južnim zaleđem. Smanjene ekonomske aktivnosti i radikalna promjena privredne strukture grada,uzrok su napuštanja proizvodnih kapaciteta, a samim tim stvaranja značajnih prostornih resursa ibraunfild lokacija. Istraživanje je fokusirano na poligon nekadašnje željezničke stanice Trebinje. Ovajneaktivni željeznički koridor ukazuje na mogućnost transformacije u linearni park, sa ciljem postizanjaekoloških, socio-ekonomskih i zdravstvenih beneficija, jer vrijednost gradskog prostora zavisi odkvantitativnog, ali i kvalitativnog udjela pejzaža u fizičkoj strukturi grada. Dakle, rezultati teoretskogistraživanja ovog rada su aplicirani kroz diskurs o razvoju i dizajnu zelene infrastrukture na konkretnojstudiji slučaja.
UTICAJ AEROZAGAĐENJA NA KARAKTERISTIKE STOMINOG I FOTOSINTETIČKOG APARATA VRSTA Tilia cordata Mill. I Tilia platyphyllos Scop. NA PODRUČJU GRADA BANJE LUKE
Authors: Janjić Nina , Maksimović Tanja
Published: May 2020

U ovom radu praćen je uticaj pojedinih polutanata na sadržaj fotosintetičkih pigmenata i broj i veličinustominih ćelija kod Tilia cordata Mill. i Tilia platyphyllos Scop. na tri lokaliteta na području grada BanjeLuke (Borik, Obilićevo i Paprikovac). Dobijeni rezultati u ovom radu pokazali su da je broj stoma u prosjekubio veći kod Tilia platyphyllos u odnosu na Tilia cordata i to na listovima koji su uzorkovani izspoljašnjeg dijela krošnje u odnosu na unutrašnji dio. Dimenzije stoma su u prosjeku bile veće kod Tiliacordata u odnosu na Tilia platyphyllos, što je genetički uslovljeno. Sadržaj ukupnog hlorofila je variraood 1,656 do 5,616 mg/g, s tim da je veći sadržaj tokom sezone utvrđen kod Tilia cordata u odnosu naTilia platyphyllos. Najveće smanjenje broja stoma i fotosintetičkih pigmenata je utvrđeno na lokalitetuBorik, gdje je i zabilježena najveća koncentracija aeropolutanata. Dobijeni rezultati ukazuju da promjeneu broju i veličini stominih ćelija i sadržaju fotosintetičkih pigmenata mogu da posluže kao indikativnipokazatelj otpornosti odabranih biljnih vrsta prema aerozagađenju.
NOTES ON SOME BRYOPHILOUS PEZIZALES (FUNGI) IN THE MEDITERRANEAN PART OF BOSNIA AND HERZEGOVINA
Authors: Jukić Nedim , Tomić Smiljan , Sabovljević Marko , Omerović Nihad
Published: May 2020

Results from bryomycological field studies in the Mediterranean part of Bosnia and Herzegovina are reportedin the paper. Five bryophilous taxa of ascomycetes have been recorded on few locations aroundthe city of Neum and on the Klek peninsula. Three of them are new for the mycobiota of Bosnia andHerzegovina – Octospora gemmicola, Lamprospora miniata var. parvispora and Lamprospora miniatavar. ratisbonensis.Macromorphology and micro-characters with ecology, phenology and distribution patterns for eachspecies are presented and briefly discussed.
Regulation of nerve growth and patterning by cell surface protein disulphide isomerase
Authors: Cook Geoffrey MW , Sousa Catia , Schaeffer Julia , Wiles Katherine , Jareonsettasin Prem , Kalyanasundaram Asanish , Walder Eleanor , Casper Catharina , Patel Serena , Chua Pei Wei , Riboni-Verri Gioia , Raza Mansoor , Swaddiwudhipong Nol , Hui Andrew , Abdullah Ameer , Wajed Saj , Keynes Roger J
Published: May 2020

Contact repulsion of growing axons is an essential mechanism for spinal nerve patterning. In birds and mammals the embryonic somites generate a linear series of impenetrable barriers, forcing axon growth cones to traverse one half of each somite as they extend towards their body targets. This study shows that protein disulphide isomerase provides a key component of these barriers, mediating contact repulsion at the cell surface in chick half-somites. Repulsion is reduced both in vivo and in vitro by a range of methods that inhibit enzyme activity. The activity is critical in initiating a nitric oxide/S-nitrosylation-dependent signal transduction pathway that regulates the growth cone cytoskeleton. Rat forebrain grey matter extracts contain a similar activity, and the enzyme is expressed at the surface of cultured human astrocytic cells and rat cortical astrocytes. We suggest this system is co-opted in the brain to counteract and regulate aberrant nerve terminal growth.
Significance of Helicobacter pylori Eradication on Atrophic Gastritis and Intestinal Metaplasia
Authors: Yoon Kichul , Kim Nayoung
Published: May 2020

There has been an accumulation of data regarding the chemopreventive effects of Helicobacter pylori (H. pylori) eradication. However, it remains unclear how H. pylori infection causes gastric cancer (GC) and how H. pylori eradication can prevent GC. Atrophic gastritis (AG) and intestinal metaplasia (IM) are known as precancerous lesions which mainly lead to intestinal-type GC but to some extent, can also lead to diffuse-type GC. The most important mechanism of AG/IM is H. pylori-induced chronic gastritis. Thus, the reversibility of AG and IM by H. pylori eradication therapy is very important in the prevention of GC. There have been many studies providing data supporting the improvement of AG by the eradication of H. pylori to some extent. In contrast, IM has been regarded as “the point of no return.” However, more recent studies have implied the improvement of IM after eradication, suggesting the importance of early eradication therapy in reversible histological status. In this review, we focused on the reversibility of AG and IM by H. pylori eradication and tried to investigate the predicting factors for the improvement of AG and IM including age, sex, smoking, and diet, as well as H. pylori infection.
Effects of Different Biomaterials and Cellular Status on Testicular Cell Self‐Organization
Authors: Gao Hui , Liu Chao , Wu Bingbing , Cui Hang , Zhao Yan , Duan Yongchao , Gao Fei , Gu Qi , Wang Hongmei , Li Wei
Published: May 2020

A multicellular organism’s development is coupled with cellular self‐organization, which is regulated by cell–cell interactions and cell–extracellular matrix (ECM) crosstalk. Testicular cells from different species such as mouse, rat, and porcine can self‐organize into seminiferous tubules both in vitro and in vivo, but the understanding of the functional role of the ECM during this process is limited. Here, it is shown that mouse testicular cells encapsulated with the biomaterial Matrigel can self‐organize into seminiferous tubules with blood‐testis barrier (BTB) formation and Leydig cell differentiation. By varying the encapsulation method, a combination of sodium alginate and collagen is used to promote reorganization of seminiferous tubules, which resemble those in vivo. In addition, the self‐organization ability of testicular cells declines with advanced cell age, and those germ cells play a pivotal role in this process. These findings will be helpful to understand the self‐organization process of testicular cells and provide insights for the reconstruction of testes.