bluuebunny/crossref_metadata_2025 huggingface dataset:
Sorption properties of suspension ointment with incorporated natural anionic polysaccharides
Authors:   Mendeleev Russian University of Chemical Technology, Trufanova Ekaterina A. , Tikhonova Tatyana V. ,   Mendeleev Russian University of Chemical Technology
Published: February 2021

Currently, there is a change in methodologies in the treatment of wounds, as a result of which the share of surgical interventions is reduced and new methods of wound care are introduced using dressings and sorption-application therapy of a new generation. The obtained experimental data on the dissolution of the standard hydrophilic ointment base and the commercial ointment Levomekol® in the Ringer-Locke model solution indicate that in real conditions, the ointment will most likely easily dissolve in physiological fluids, quickly absorb and promote the adhesion of the dressing to the wound. The sorption properties of both individual anionic polysaccharides and their mixtures in various ratios in a Ringer-Locke model solution containing the main exudate cations (Na+, K+, Ca2+) were studied in order to assess the prospects of their use as a solid phase in the development of a suspension ointment with sorption properties. This publication presents the results of the behavior of a suspension ointment with anionic hydrocolloids and a commercial ointment Levomecol® in a Ringer-Locke model solution. It is shown that a mixture of sodium alginate and Kappa-carrageenan in a ratio of 1:2 in the developed suspension ointment retained a significant amount of the model solution (24.5 g/g) in its volume for 24 hours. Increasing the sorption capacity of hydrophilic ointments based on PEO will allow you to Sorb excess exudate, create a microclimate to accelerate healing processes, and reduce tissue trauma when removing the dressing.
Comparative analysis of the various structures quinoline derivatives retention under RP HPLC
Authors:   Samara National Research University, Kholin Andrey Yu. , Kurbatova Svetlana V. ,   Samara National Research University, Zemtsova Margarita N. ,   Samara State Technical University
Published: February 2021

The study results of the structure and physicochemical parameters effect of various quinoline derivatives on their retention under conditions of reversed-phase high-performance liquid chromatography are presented. It is shown that since the establishment of the relationship between the structure of a substance and its properties is still one of the most important problems of modern chemistry and materials science, chromatography is a very convenient and effective method for obtaining the information necessary for this. To establish the relationship between the structure and sorption characteristics of substances, on the one hand, the parameters of the electronic structure of sorbate molecules, their hydrophobic properties, quantum-chemical, topological and other physicochemical characteristics of organic compounds are used, as well as various computer programs and computer modeling methods that make it possible to analyze and to compare the numerous data on the chromatographic retention of compounds of various chemical nature, on the other. At the same time, for the final conclusions about the possibility of using the obtained dependences and correlations for assessing and predicting the properties of new compounds, a significant sample of compounds of various compositions is required, with the use of which the corresponding "structure – property" relationships are obtained. By now, reference books and computer databases on the chromatographic retention of organic compounds are known, containing information on a fairly large number of objects. However, these databases usually contain information predominantly about the retention of compounds under gas chromatography conditions. There are practically no corresponding libraries and databases for liquid chromatography, which is primarily due to the variety of liquid chromatographic systems differing both in the nature and composition of stationary phases and eluents, and in the chromatographic conditions. For the conditions of liquid chromatography, the possibility of using such schemes is complicated by the existence of a large number of interactions in the chromatographic system, due, first of all, to the presence of an active eluent. It is shown in this work that heterocyclic compounds are suitable models for these purposes, a feature of which is the possibility of modifying their properties by varying the structure within wide limits. In this work, the influence of the presence of heteroatoms, a change in the position of the same heteroatom in the main heterocyclic fragment, and the presence of functional groups and substituents of various natures on chromatographic retention under RP HPLC conditions were studied.
Amphiphilic silica derivatives associated with oligomeric medium in octamethylcyclotetrasiloxane polymerization
Authors:   Kazan National Research Technical University, Davletbaev Ruslan S. , Faizulina Zulfia Z. ,   Kazan National Research Technological University, Akhmetova Albina I. ,   Kazan National Research Technological University, Izmailov Samat R. ,   Kazan National Research Technological University, Demin Daniil A. ,   Kazan National Research Technological University, Davletbaeva Ilsia M. ,   Kazan National Research Technological University
Published: February 2021

The amphiphilic derivatives of silica associated with oligomeric medium have been studied as modifiers of the catalyst for the octamethylcyclotetrasiloxane polymerization of anionic nature. The effect of the modifiers structure on the polymerization time of the obtained polydimethylsiloxanes was investigated. It was found that the modifier, like the initial polyoxyethylene glycol, exhibits the properties of promoters for the catalytic polymerization of octamethylcyclotetrasiloxane by the anionic mechanism. To establish the role of amphiphilic silica derivatives in the occurrence of intermolecular interactions in polydimethylsiloxanes that were obtained with them, the regularities of changes in the reduced viscosity of the obtained modified polydimethylsiloxanes were analyzed. It has been established that the reduced viscosity of polydimethylsiloxanes increases with an increase of the modifier amphiphilicity. This is due to the occurrence of intermolecular interactions because the specific interaction of amphiphilic silica derivatives with polydimethylsiloxane macromolecules. When using amphiphilic derivatives of silica as a modifier of the resulting polydimethylsiloxane to a content of 6 wt% hydrophobic fragment in their composition, modification of polydimethylsiloxanes does not affect their rheological characteristics. This is due to the presence of polyoxyethylene branches in the composition of the modifier, which creates a cavity for the trapping of K+ ions, as in the crown ether, they perform only a catalytic function, which leads to an increase in the rate of the process. However, starting from 10 % wt the content of the hydrophobic component in the composition of the modifier, the reduced viscosity of the obtained polydimethylsiloxane increases due to the occurrence of intermolecular interactions between the modifier and the obtained polydimethylsiloxane. It was noted that polydimethylsiloxane obtained using only polyoxyethylene glycol as a modifier exhibits viscosity characteristics lower than polydimethylsiloxane obtained by the anionic mechanism without using any modifiers.
Comparative analysis of the structure of coals of different stages of metamorphism according to 13C NMR data
Authors:   Federal Research Center of Coal and Coal-Chemistry of SB RAS, Lyrshchikov Sergey Yu. , Sotnikova Larisa V. ,   Federal Research Center of Coal and Coal-Chemistry of SB RAS
Published: February 2021

In this paper, the method of cross-polarization with magic angle rotation and decoupling from protons (CPMAS) 13C NMR spectroscopy obtained quantitative data on the distribution of carbon over structural fragments and calculated the degree of aromaticity (fa) of some coal samples from various Siberian deposits of a wide range of metamorphism. All the coals used in the work were characterized by standard methods (proxymate and ultimate analysis). The optimal parameters of the pulse program for recording the spectra of coals have been determined. To obtain quantitative data, the spectra were simulated. The spectrum model included from 9 to 13 components, depending on the stage of coal metamorphism. The dependences of the degree of aromaticity and the sum of oxygen-containing functional groups on the stage of coal metamorphism were constructed. The results obtained show that the structure of coals regularly changes depending on the stage of their metamorphism. The revealed relationships of the structure and properties of coals, together with the parameters of their reactivity, can ensure the safe behavior of coals in the processes of mining and processing, as well as in determining possible ways of using the studied coal samples as a valuable chemical raw material.
The composition of the vapor phase upon evaporation of a mechanical mixture of cadmium and zinc selenotelluride powders
Authors:   St. Petersburg State Chemical-Pharmaceutical University, Belyaev Alexey P. , Mokhorov Dmitry A. ,   Peter the Great St. Petersburg Polytechnic University, Antipov Vladimir V. ,   St Petersburg State Institute of Technology (Technical University)
Published: February 2021

The effect temperature has on the composition of a vapor phase passed through a thermal field after the evaporation of a mechanical mixture of the powders of cadmium and zinc selenotelluride is studied. It is found that the composition of the vapor phase can be changed throughout the range of concentrations by varying the temperature. The results of the study are satisfactorily explained by the effect temperature has on the particle distribution function in correspondence to the weights of the molecules constituting the mixture. There were virtually no molecules of the evaporated substance in the vapor phase, which consisted of diatomic molecules of the elements of Group VX compounds and metal atoms. This means that with the evaporation of mechanical mixtures of CdTe and CdSe powders, the vapor phase in the evaporator contains only Cd, Se2, and Te2 molecules, while mixtures of ZnTe and ZnSe powders contain Zn, Se2 and Te2 molecules. Despite the similarity between the components’ heats of sublimation, their concentrations over the powdermixture did not correspond to the composition of the powder mixture, since compounds A2B6 sublimate incongruently. Coming from the evaporator, the vapor phase entered the thermal field and was condensed onto a substrate at room temperature at its outlet. As follows from the composition of the substrate films, the vapor phase at the outlet was enriched with the light component Se, compared to the powder mixture. By virtue of the law of the conservation of mass, the vapor phase was therefore enriched with the heavy component Te at the inlet to the thermal field. Our results show that the thermal field controls the composition of the vapor phase by changing the particle distribution function according to the weight of the molecules constituting the mixture. The temperature dependences of the composition of the vapor phase are presented for several mechanical mixtures of the powders of (CdSe)x (CdTe)1-x and (ZnSe)x (ZnTe)1-x, where x = 0.45-0.90.
Calculation of the main technological parameters of the apparatus for receiving raw materials used in the production of medical application sorbent
Authors:   Kazan National Research Technological University, Valeev Ilnar A. , Zhukova Irina V. ,   Kazan National Research Technological University, Girfanutdinov Azat A. ,   Kazan National Research Technological University
Published: February 2021

Analysis of the consumption of activated carbon on the international market showed sufficient demand for this topic, both for medical and for most industries. Sorbents are a large class of drugs that are able to excrete a wide variety of toxic substances from the body. The activated carbon market in the Russian Federation was focused on the military-industrial complex, due to which the range of goods was very limited. Due to the current situation, activated carbons produced by our industry are universal and, therefore, ineffective for specific tasks. Based on this, the problem of inexpensive and effective sorbents is very relevant and the lack of active coal reaches several tens of thousands per year. This problem is being solved for the most part by importing the product. The urgency of the problem poses the task of quickly introducing this type of installation and effectively calculating its technical parameters for subsequent manufacturing. The task of the engineering method of calculation is the operational calculation of the given source data, the design parameters of the apparatus. The possibility of using waste wood processing enterprises has shown that the use of this type of raw material is justified and effective. Both in terms of cost, and in terms of beneficial use of tree illiquid. Technical innovations and proven solutions used in the experimental setup will significantly intensify the pyrolysis process while improving product quality and reducing its cost. An algorithm for calculating the main technical parameters of the camera. It includes several blocks responsible for each parameter. Calculation of geometric parameters allows you to develop an installation of strictly the required geometric size based on the necessary raw materials needs. Aerodynamic calculation takes into account the whole process of preparing raw materials and allows you to select the necessary attachments strictly according to the required parameters. Thermal calculation allows you to select the materials of the chamber from the required temperature range required for more efficient raw materials production with the optimal characteristics.
Content of double bonds in polyethylene
Authors:   METACLAY Research and Development LLC, Meshalkin Andrey O. , Tsyutskoma Ulyana Yu. ,   METACLAY Research and Development LLC, Leonova Olesya I. ,   METACLAY Research and Development LLC, Bahov Fedor N. ,   METACLAY Research and Development LLC, Moskvitin Lev V. ,   METACLAY Research and Development LLC, Arsentiev Mihail A. ,   METACLAY Research and Development LLC, Berezin Nikolay B. ,   Kazan National Research Technological University, Mezhevich Zhanna V. ,   Kazan National Research Technological University
Published: February 2021

The content of double bonds in high-pressure polyethylene of various brands obtained from Russian and foreign manufacturers was studied. The essence of the method was to build a calibration curve on an infrared Fourier spectrometer for standard substances with a previously known arrangement of the double bond, saturation of double bonds in the initial polyethylene using gaseous bromine, and subsequent assessment of the locations and number of double bonds in the studied brands of high pressure polyethylene. The calibration substances were trans-4-decene with a purity of 96%, 1-decene with a purity of 95%, and 2-methyl-1-heptene with a purity of 98%. To record infrared spectra, calibration substances were dissolved in carbon disulfide with a purity of 99.5%. The spectra of the calibration substances were recorded in the transmission mode. The recording of the spectra of the high-pressure polyethylene samples was carried out in the reflection mode. To calculate the molar adsorption coefficient of individual calibration substances, the areas of the peak absorption of individual substances were allocated. The Peak Separation NETZSCH software was used for this purpose. For all analyzed samples, both brominated and not brominated, the ratio of the areas of absorption peaks was calculated. For each sample of high-pressure polyethylene, the content of trans-vinylidene, vinyl, and vinylidene groups C=C per 1000 carbon atoms was determined. The total number of double bonds was calculated as the sum of all analyzed bonds contained in the polyethylene sample. The accuracy of the analysis method performed by a single laboratory on a single sample is ±10% of double bonds per 1000 carbon atoms. The technique allows one to evaluate such a characteristic of low density polyethylene as the content of double bonds. This characteristic is essential for the efficient development of crosslinkable polyethylene compounds.
Peculiarities of thermal aggregation of bovine serum albumin in the presence of strong polyelectrolytes
Authors:   Vladimir State University named after A.G. and N.G. Stoletovs, Smirnova Natalia N. , Smirnov Kirill V. ,   Vladimir State University named after A.G. and N.G. Stoletovs
Published: February 2021

The influence of temperature on bovine serum albumin (BSA) aggregation in aqueous solutions in the presence of poly-N,N-dimethyl-N,N-diallylammonium chloride (PDMDAAC) and the sodium salt of carboxymethylcellulose (CMC) was studied. It was shown that protein-polyelectrolyte complexes (PPC) form because of macromolecular reactions that are stabilized mainly by electrostatic forces. To characterize the PPC composition the φ parameter was used. This parameter is defined as the ratio of the concentration of ionic groups of polyelectrolyte per protein molecules. It was studied that when in an interpolyelectrolyte reaction, a sufficiently high degree of transformation occurs the polymer electrolyte initiates aggregation of protein molecules. As the temperature increases, the initiating role of the polymer electrolyte increases due to an increase in the intensity of hydrophobic interactions. Using the method of spectrophotometry, it was found that, depending on the nature of the polymer electrolyte, insoluble complexes of bovine serum albumin are formed when the pH parameter is above or below the isoelectric point of the protein, when its macromolecules are negatively or positively charged. In the presence of poly-N,N-dimethyl-N,N-diallylammonium chloride, the intensive formation of aggregates and their rapid precipitation in the form of flakes at pH > 7.0 was observed when the temperature increased to 60 °C. The maximum yield of the product of the interpolyelectrolyte reaction bovine serum albumin – sodium salt of carboxymethylcellulose was detected at pH ≤ 4.0. A temperature increase up to 60 °C, in this case, was not accompanied by intensive flocculation. Under optimal composition and interaction conditions, the degree of transformation in the BSA – PDMDAAX and BSA – CMC reactions is ~0.93 and 0.9, respectively, and decreases by ~5-7% with an increase in temperature to 60 °C. It was shown that for the same BOD composition (the ratio of components in the [CMC]/[BSA] complex = 0.1 g/g), an increase in temperature from 25 to 60 °C leads to the formation of particles that increase in size from 1 mcm to 5 mcm. The temperature increase leads to a change in composition of BOD, corresponding to its maximum output as a interpolyelectrolyte reactions product: for complex with PDMDAAC at T = 25, 40 and 60 °C, the φ value is 70, 60, 15; for the complex with the CMC – 60, 50, 20.
Study of the sorption capacity of soluble forms of yeast beta-glucan
Authors:   D. Mendeleev University of Chemical Technology of Russia, Kurochkina Anna S. , Krasnoshtanova Alla A. ,   D. Mendeleev University of Chemical Technology of Russia
Published: February 2021

Beta-glucans are polysaccharides that consist of D-glucose residues linked together in the main and side chains by glycosidic bonds. They are obtained from plant and microbial raw materials. Beta-glucans obtained from various sources differ in molecular weight, backbone length, branching of additional chains and their number. Beta-(1,3,1,6)-glucan from the yeast Saccharomyces cerevisiae has the highest physiological activity. The soluble fraction of beta-glucan has a higher physiological activity than its insoluble fraction. As a rule, soluble beta-glucans appear to be more potent immunostimulants than insoluble ones. In this regard, obtaining soluble forms of beta-glucan from yeast is relevant. The purpose of this work was to study the effect of the content of the soluble fraction in yeast beta-glucan on the ability to adsorb heavy metal ions, mycotoxins and cholesterol. Evaluation of the effectiveness of ultrasonic treatment for obtaining soluble forms of yeast beta-glucan was carried out. It was found that the maximum content of the soluble fraction, equal to 95%, at a frequency of ultrasonic treatment of 85 kHz for a laboratory sample of beta-glucan, is achieved with a treatment time of 20 min, and for a commercial one – in 30 min. The sorption properties of soluble forms of yeast beta-glucan with different content of the soluble fraction in relation to cholesterol, aflatoxin and bivalent copper cations were studied. The sorption capacity of samples of laboratory and commercial preparations of beta-glucan was determined for the above compounds. It was found that an increase in the content of the soluble fraction to more than 50% does not lead to a noticeable increase in the sorption capacity. It was shown that purified samples of beta-glucan have higher sorption characteristics.
Application of high-performance liquid chromatography- time-of-flight mass spectrometry for determination of neonicotinoid lethal bee intoxicants
Authors:   Federal Center for Toxicological, Radiation and Biological Safety, Rakhmetova Elvira R. , Fitsev Igor M. ,   Federal Center for Toxicological, Radiation and Biological Safety, Mukharlyamova Aisylu Z. ,   Federal Center for Toxicological, Radiation and Biological Safety, Burkin Konstantin E. ,   Federal Center for Toxicological, Radiation and Biological Safety, Sayfutdinov Alexander M. ,   Federal Center for Toxicological, Radiation and Biological Safety, Shlyamina Oksana V. ,   Federal Center for Toxicological, Radiation and Biological Safety, Nasybullina Zhanna R. ,   Federal Center for Toxicological, Radiation and Biological Safety
Published: February 2021

The use of uncontrolled toxic concentrations of systemic insecticides belonging to the class of neonicotinoids in agriculture has a negative impact on the life of honeybees. The situation is aggravated by the fact that compared to other pesticides, neonicotinoids have acute toxicity to bees, contributing to their death. This paper presents a developed multimethod for qualitative and quantitative determination of certain lethal bee intoxicants of a number of neonicotinoids: thiamethoxam, clothianidin, Imidacloprid and acetamiprid by high–performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (HPLC-MS/MS). Sample preparation for HPLC-MS/MS was carried out using a modified QuEChERS method, followed by post-treatment of samples by dispersion solid-phase extraction (TFE). Chromatographic separation was performed by gradient reverse-phase HPLC, detecting neonicotinoids in the multiple reaction monitoring (MRM) mode. The assessment and verification of the completeness of the degree of recovery of neonicotinoids by the modified version of QuEChERS, based on the results of HPLC-MS/MS definitions, indicate that a high degree of their recovery has been achieved. Under the proposed conditions of chromatographic separation, the analytical signals of the determined neonicotinoids are characterized by correlation coefficients (r2) equal to 0.999. The limits of detection (3·Sa/b) of neonicotinoids detected under HPLC-MS/MS conditions are established, which are: 1.6.10-3 mg/kg of thiamethoxam and Imidacloprid; 1.8.10-3 mg/kg of acetamiprid and 1.9.10-3 mg/kg of clothianidine. The developed HPLC-MS/MS multimethod is used for screening the material of dead bees for neonicotinoids, which are their lethal intoxicants.
Thermodynamic probability of formation solid solutions FexPb1-xS by hydrochemical precipitation
Authors:   Ural Federal University Named after the First President of Russia B.N. Yeltsin, Maskaeva Larisa N. , Beltseva Anastasia V. ,   Ural Federal University Named after the First President of Russia B.N. Yeltsin, Pozdin Andrew V. ,   Ural Federal University Named after the First President of Russia B.N. Yeltsin, Markov Vyatcheslav F. ,   Ural State Fire Service Institute of Emergency Ministry  of Russia
Published: February 2021

Analysis of the literature showed that narrow-gap lead sulfide PbS (0.4 eV at 300 K), due to its unique properties, has found wide application in such devices as photodetectors with a wide (from infrared to ultraviolet) radiation range, solar energy converters, chemical sensors, temperature sensors, flame detectors, etc. Doping of lead sulfide with various metal ions can affect the bandgap, and hence expand the scope of its application. Of particular interest is the preparation of thin film solid solutions in the PbS – FeS system, which can lead to the appearance of ferromagnetism in lead sulfide. To obtain doped films of lead sulfide and solid solutions based on it, the method of chemical deposition from aqueous media is considered promising, which, in addition to its cost-effectiveness and simplicity of the process, allows one to determine in advance the areas of formation of the semiconducting metal chalcogenides of interest. The analysis of ionic equilibria in the systems "PbAc2 – FeCl2 – Na3Cit – NH4OH – N2H4CS", "PbAc2 – FeCl2 – NaAc – NH4OH – N2H4CS "and " PbAc2 – FeCl2 – Na2С2О4 – NH4OH – N2H4CS "made it possible to reveal predominantly forms of metals in a given pH range. To assess the conditions for the deposition of the main and impurity phases by thermodynamic calculations taking into account the sizes of critical nuclei, the boundary conditions and regions of the formation of FeS, PbS, Fe(OH)2, Pb(OH)2 in the reaction systems under study were found. It is shown that the most promising for the preparation of the three-component PbFeS compound, which does not contain impurity phases of lead and iron hydroxides, is the reaction system "PbAc2 – FeCl2 – Na3Cit – NH4OH – N2H4CS". The possibility of obtaining PbS: Fe films with a uniform iron distribution of ~ 0.5 at.% and deviation from stoichiometry towards Pb deficiency (47.7 at.%) and S excess (50.7 at.%) was experimentally demonstrated.
Thermodynamic modeling of metals reduction from B2O3-CaO-FeO-NiО melts by carbon monoxide and hydrogen
Authors:   Institute of Metallurgy Ural Branch of RAS, Vusikhis Alexander S. , Selivanov Evgeny N. ,   Institute of Metallurgy Ural Branch of RAS, Tyushnyakov Stanislav N. ,   Institute of Metallurgy Ural Branch of RAS, Chentsov Viktor P. ,   Institute of Metallurgy Ural Branch of RAS
Published: February 2021

Thermodynamic modeling method have been used to describe the process of Iron and Nickel joint reduction from oxide melt of the B2O3-CaO-FeO-NiO system by Carbon monoxide and Hydrogen. Fractional inducing of reducing agent and periodic removal of metal gases from working body composition are applied in the method. The equilibrium states are determined for each unit portion of gas, and oxide component composition of the working body in each calculation cycle is taken from the previous data. Such approach is originality of the method. The approach gives possibility to bring the simulated processes closer to real technologies as well as to estimate reactions completeness in pyrometallurgical aggregates. The calculations were carried out accounting disproportionation of FeO into Fe and Fe3O4. It was shown that as a result of FeO disproportionation under neutral conditions (Ar), the resulting metallic Iron interacts with Nickel oxide to form ferronickel. As a result, the initial composition of the B2O3-CaO-FeO-NiO system variation, take place. Additionally, Fe3O4 appears in the working body. The relationship of Iron and Nickel oxides contents in oxide melt, degrees of its reducing and composition of ferronickel formed depending on temperature and induced reducing agent are revealed. The Hydrogen quantity consumed for metal reducing, at which the same degree of Nickel metallization is achieved, is much less comparing to CO. However, the resulting ferroalloy has less Nickel content, which is associated with increase of reduced Iron content. The obtained information is useful for prognoses of thermal extraction processes acting during useful components extraction from oxide melts, for example, nonferrous metallurgy slag.
Chemical composition of the washing water solution after washing the wheelsets of railway transport
Authors:   F.M. Dostoevsky Omsk State University, Bezzubov Alexander N. , Golovanova Olga A. ,   F.M. Dostoevsky Omsk State University
Published: February 2021

The article discusses the impact of economic and industrial water consumption on the state of the hydrosphere and biosphere of the Earth, and also presents the water consumption in Russia, the share of the country's water resources consumed per year and the forecast of water consumption at the end of 2020. The classification of modern methods of wastewater treatment, including in railway depots, is considered. The water consumption and the proportion of circulating water at railway enterprises are analyzed in detail, as well as the most used methods of purification of the used detergent solution (DS) in the enterprise are presented. The description of the work presents the key characteristics of the DS after washing the wheelsets of railway transport, such as pH, total hardness, density and permanganate oxidizability. The data obtained were compared with the requirements (2.1.4.1074-01) and concluded that the water was unsuitable for further operation due to a significant excess of the norm for permanganate oxidizability. The effect of long-term sedimentation of the studied DS was investigated, after which DS was successfully separated into an aqueous phase, an organic phase, a black amorphous organic precipitate, and a yellow amorphous precipitate. The influence of a direct electric current, conducted through the solution at room temperature on carbon electrodes, was studied for a time of 30 minutes, one and three hours. The influence of changes in the pH of the DS medium with subsequent settling was studied. The results of chemical purification of the water under study with such coagulants as ammonium polymolybdate and bismuth(III) salts, the latter of which made it possible to precipitate phosphate ions from solution, are presented. A qualitative reaction with the use of ammonium thiocyanate proved the content of iron(III) ions in the test solution.
Synthesis and study of the reactivity of 1,1'-oxalyl di(2-methylimidazole) in reactions with N-nucleophiles
Authors:   Samara National Research University, Purygin Pyotr P. , Fedotova Viktoriya D. ,   Samara National Research University, Alekseev Vitaly Yu. ,   Samara National Research University, Zarubin Yury P. ,   Samara National Research University
Published: February 2021

This article describes the synthesis of 1,1'-oxalyl di(2-methylimidazole), which was obtained in two stages. At the first stage of the synthesis, 1-trimethylsilyl-2-methylimidazole and oxalyl chloride were obtained. At the second stage of the synthesis, the target product was obtained by reacting 1-trimethylsilyl-2-methylimidazole with oxalyl chloride. The product was a dark crystalline substance, the yield of the final product was 83%. The structure of 1,1'-oxalyl di(2-methylimidazole) was confirmed by IR and 1H NMR spectroscopy. In the IR spectra, characteristic absorption bands were found, confirming the presence of the corresponding functional groups in the structure of the compound, in the 1H NMR spectrum, proton signals with characteristic chemical shifts for the corresponding functional groups were found. The PASS online software predicted the types of biological activity of the compound under study. The most probable possibilities of application in the treatment of urological diseases, diabetes mellitus, staphylococcal, oncological diseases, antiaggregatory action. For the 1,1'-oxalyl di(2-methylimidazole) molecule, 6 conformers were found, which were three pairs of enantioconformers in the Molecular Operating Environment 2009.10 software, for which the electrostatic potential, nucleophilic and electrophilic susceptibility surfaces were calculated in the SCIGRESS Modeling 3.1.4 software. It was shown that the interaction with nucleophilic reagents is most typical for the 1,1'-oxalyl di(2-methylimidazole) molecule. Calculations of the potential energy of the conformers of 1,1'-oxalyl di(2-methylimidazole) molecules have been carried out. Using 1,1'-oxalyl di(2-methylimidazole), the syntheses of acetanilide, benzanilide and diethylformamide were carried out. These syntheses were carried out in order to test the reactivity and the possibility of amide-type bond formation upon activation of the carboxyl group in carboxylic acids. The reactions were carried out in one stage without isolation of the intermediate 2-methylimidazolide of the corresponding carboxylic acid. In this case, the proposed reaction mechanism should be two-stage. Possible structures of reactants, transition states, and reaction products in the interaction of 1,1'-oxalyl di(2-methylimidazole) with carboxylic acids and amines have been calculated by methods of computational chemistry.
Synthesis of the FePt nanosystem: comparison of the synthesis methods
Authors:   Federal Research Center on Coal and Coal Chemistry, Zaharov Nikita S. , Popova Anna N. ,   Federal Research Center on Coal and Coal Chemistry, Zaharov Yury A. ,   Federal Research Center on Coal and Coal Chemistry, Grishaeva Olga V. ,   Federal Research Center on Coal and Coal Chemistry
Published: February 2021

In this work, using the example of the synthesis of nanoparticles of the mutual FePt system, obtained in an aqueous medium by the method of co-reduction of solutions of metal precursors, the effect of reducing agents is considered: an alkaline solution of hydrazine hydrate and sodium tetrahydroborate in combination with a stabilizer of sodium-potassium tartrate. The main characteristics of the obtained nanosized particles of the iron-platinum system were studied by means of a complex of physicochemical methods of analysis. The shape and morphology of the obtained nanosized particles were studied by transmission electron microscopy, phase analysis and X-ray structural parameters – by X-ray diffraction methods. It was approached to reveal the dependence of the particle size on the type of reducing agent used. It was found that nanosized FePt particles obtained with different reducing agents have similar physicochemical characteristics. The use of sodium tetrahydroborate, in the presence of a stabilizer sodium-potassium tartrate, allowed to obtain more dispersed particles with a size of 14.3±2.1 nm. FePt nanoparticles reduced by hydrazine hydrate were characterized by large sizes of 16.7±4.0 nm, and the particles form large dense agglomerates. Chemical analysis showed that when reducing with sodium tetrahydroborate, the target product contained 0.4 mol. % boron. When reducing FePt nanoparticles with hydrazine hydrate, it was found that the target product was contaminated with iron oxide, which was also confirmed by X-ray phase analysis. X-ray diffraction analysis showed that the iron-platinum nanosystem was represented by a solid-solution phase with a face-centred cubic lattice. The parameters of the crystal lattice were estimated, 3.908 Å and 3.894 Å, respectively, for FePt nanoparticles obtained using NaBH4 and N2H4∙H2O.
Physico-chemical study of complexing processes in AlCl3-L-H2O system where L – DPA, centralite, DNT, DBP
Authors:   State Research Institute of Chemical Products, Gatina Rose F. , Klimovich Olga V. ,   State Research Institute of Chemical Products, Mikhailov Yury M. ,   State Research Institute of Chemical Products
Published: February 2021

This work presents a method of powder components’ interaction, containing a trivalent nitrogen and other atoms with an undivided electron pair (UEP) with the aqueous solutions of complexing extragents. In the role of the latter, an aqueous solution of aluminium chloride was studied. Diphenylamine (DPA), centralite 1 (or diethyldiphenylurea), dinitrotoluene (DNT) and dibutylphthalate (DBP) were considered as organic components. A donor-acceptor mechanism of the reagents’ interaction is proposed, in which a section of a molecule of an organic component of powder, containing an element atom with UEP, acts as a donor of the electron pair; an aluminium ion with free p- and d-orbitals acts as an acceptor. It is the presence of both types of free orbitals that allows Al3+ ion to increase its coordination up to 6 in complex compounds, which it forms. The complex compounds (CCs) of aluminium chloride and powder components with the trivalent nitrogen atom and with other atoms with UEP were obtained in an aqueous medium. CCs were studied by the methods of the physico-chemical analysis such as conductance-measuring and titrimetric methods (complexation and agrentometric titration), chromatographic methods (thin-layer chromatography and gas-liquid chromate-graphy) and spectral methods (IR- and UV-spectrometry). The fragments of functional groups, involving in the formation of the intermolecular bonds such as amino group in DPA molecule, carbonyl group in centralite 1 molecule, nitro group in DNT molecule, ester group in DBP molecule and π-system of aromatic ring in all molecules of the considered organic components of powder, were revealed. It is found that a reason for an increase in a solubility of organic compounds of powder in water is the formation of complex compounds such as “double salts”. The optimal conditions for obtaining CCs such as “double salts” were determined. Later, this fact was applied for an extraction of these components from a powder composition.
Research of the adsorption of aliphatic carboxylic acids on the surface of polysorb
Authors:   Chelyabinsk State University, Kimyashov Alexander A. , Syromolotov Alexander V. ,   Chelyabinsk State University, Pavlov Maksim O. ,   Chelyabinsk State University
Published: February 2021

The enterosorbent "Polysorb" is a highly dispersed powder of silicon dioxide. In medicine, it is used as a detoxifier for poisoning with organic substances and heavy metals. Recently, the direction in pharmaceuticals related to targeted delivery of medicines has begun to develop. One of the carriers of medicinal substances is highly dispersed silicon dioxide. There are explorations that show that with simultaneous oral administration of highly dispersed silicon dioxide and the antibiotic amphotericin, the concentration of the latter in the blood increases significantly. Recently, there have been studies showing that delivering propionic acid to the gut reduces fat accumulation in overweight people. The goal of this work is study the adsorption of aliphatic carboxylic acids, namely: formic, acetic, propionic on the surface of polysorb. Using electron microscopy, it was shown that polysorb powder consists of particles of different sizes and shapes. Their size varies from units to tens of micrometers. Adsorption isotherms of formic, acetic, and propionic acids were constructed at a temperature of 295 K. It is shown that they have an S-shaped character, therefore, adsorption is due to the formation of hydrogen bonds between the silanol groups of the hydrated POLYSORB and the carboxyl groups of acids. It is established that these isotherms are adequately described by the Freundlich model up to the saturation region. With an increase in the hydrocarbon radical, the adsorption capacity of acids decreases. The kinetics of acid adsorption on the polysorb surface was described using pseudo-first and pseudo-second order models. It was found that the adsorption kinetics of carboxylic acids is adequately described by the pseudo-first-order model. The time of onset of adsorption equilibrium is 30 seconds at a temperature of 295 K.
Determination of concentration equilibrium of the substance being measured in a supercritical solvent with a dynamic research method
Authors:   Kazan National Research Technological University, Yarullin Lenar Yu. , Gabitov Farizan R. ,   Kazan National Research Technological University, Sabirova Lyudmila Y. ,   Kazan National Research Technological University, Antonova Polina V. ,   Kazan National Research Technological University
Published: February 2021

At present, there is no universal method for studying the solubility of substances in supercritical fluid media. The expediency of combining certain methods of solution saturation and composition analysis is determined by the object of study, the range of concentrations. In the case of low solubility of solids in the solvent, a flow-through system or dynamic solubility measurement method is usually used to obtain the required amount of precision weighing material. The dynamic method for measuring the solubility of substances in supercritical carbon dioxide is not without its drawbacks, which primarily include the need to strictly control the mass flow rate of supercritical carbon dioxide in the cell with the substance being measured. With an increase in the consumption of supercritical dioxide from zero (static method) to a certain value, the concentration of the measured substance in supercritical carbon dioxide within the acceptable level of uncertainty for measuring the solubility of 4-6% can be considered unchanged. The plateau of the concentration of the measured substance in supercritical carbon dioxide from the flow rate obtained in the diagram corresponds to the saturation state of the solvent, which is carbon dioxide and the solute, which corresponds to the concept of solubility. However, with a further increase in the consumption of carbon dioxide, the concentration begins to decrease and it can no longer be considered equilibrium. This is due to the fact that at significantly high flow rates of carbon dioxide, which is a solvent, coming into contact with the substance being dissolved, it does not have time to saturate it and, accordingly, weakly dissolves it. This concentration does not correspond to the concept of solubility. Thus, the determination of the range of mass flow rate at which the conditional state of saturation of the solvent and the solute is reached is the most important stage in studies to measure the solubility of substances in supercritical fluids. Based on the results of experimental data measuring the solubility of tannin in supercritical carbon dioxide, the dependences of the concentration of tannin in supercritical carbon dioxide on the mass flow rate are presented. It follows from the results that, in the flow rate range of 0-0.6 g/min, the tannin concentration in supercritical carbon dioxide is practically independent of the solvent flow rate, which is evidence of the equilibrium of this concentration and its compliance with the concept of solubility.
Refinement of the relationship between effective radii and ionization energies of alkali metal atoms
Authors:   Samara State Transport University, Yakovlev Victor M. , Garkushin Ivan K. ,   Samara State Technical University, Burchakov Alexander V. ,   Samara State Technical University
Published: February 2021

One of the key explanations for the peculiarities of the change in the first ionization energies (IE Ei1) of the elements of the periodic table is based on the postulation of an unambiguous relationship between Ei1 and atomic radii (rat). Due to the certain conventionality of the rat parameters, they do not belong to the category of attributive atomic characteristics. Usually they are found either by implementing various kinds of theoretical or semi-empirical calculation schemes, or by using experimental data on Ei1 for the corresponding approximations. As follows from the literature data, the known values of rat, even in the case of "quasi-hydrogen-like" alkali metals (AM), –relatively simple manyelectron systems – are characterized, as a rule, by a significant scatter. In addition, the canonical analytical formulas describing rаt within the framework of a hydrogen-like model with two effective interaction parameters (according to Slater) do not ultimately lead to adequate results in this set of elements. In this work, to correct the relationship rat = f (Еi1) related to the properties of the aggregate of alkaline elements, the publication of the effective Slater radii (reff) and Weber-Cromer orbital radii (rorb), and some results of later data are used. The effective principal quantum numbers n* for each of the AM (except for Li, for which it is assumed that n*=n=2) are estimated on the basis of the values of Ei1. A further step, by introducing n*, made it possible to use the criterion for optimizing the value of the effective radius r* and to correct the formula that determines its relationship with Ei1 in the form of a simple power function. At the same time, the radii Li, Na, and Fr have been refined towards some underestimation, compared with rorb. Arguments are presented in favor of the reliability of the proposed approach. It is shown that the obtained estimates of r* correlate better with the amplitudes of the solution of the wave equation covering all AMs than the known corresponding values of rorb and reff.
Laboratory methods for producing of effective adsorbents on the basis of diatomite for purification of water from impurities of well-soluble organic compounds
Authors:   Institute for Chemical Reagents and High Purity Chemical Substances of NRC «Kurchatov Institute», Ubaskina Yulia A. , Alekhina Marina B. ,   D. Mendeleev University of Chemical Technology of Russia
Published: February 2021

Today there is the problem of fine water purification during its consumption and disposal in industry from impurities of water-soluble organic compounds that enter it with pharmaceutical, cosmetic preparations, food waste, waste from the textile and chemical industries. Diatomite is a good raw material for the production of these adsorbents. It is found that diatomite is the mesoporous sorbent. The permeability of diatomite can be increased by granulating of the rock. It is found that heat treatment is necessary to obtain more durable granules from diatomite: when the increasing in the temperature of heat treatment of granules the compressive strength of granules increases too. At the same time, when the temperature of the heat treatment is increasing, the equilibrium adsorption of methylene blue on diatomite granules is decreasing. The optimum temperature for the heat treatment of granules is 550 °C. It is found that the heat treatment and granulation of diatomite do not have a significant impact on the adsorptive-structural properties of the rock: up to 70 % of the pore volume of granules is the volume of mesopores. The powdered adsorbent from diatomite which can be obtained by the developed laboratory method can be used in industrial water purification schemes where static adsorption is used for fine water purification. Using the developed laboratory method for producing granular adsorbent from diatomite, it is possible to produce an adsorbent for water purification under dynamic adsorption conditions, where a high value of the sorbent permeability is important.