Investigation of Structural Phase Conversions of an Iron-Containing Catalyst by Mossbauer Spectroscopy (Part 1)

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. The active form of an iron-containing catalyst including mixed Fe(II, III) oxides for refi ning Ashal′cha heavy oil was investigated using Mossbauer spectroscopy to establish the formation mechanism. The iron-oxide phase is involved during the formation process in the cleavage of carbon-heteroatom bonds in asphaltene and resin fractions of heavy oil and decreases their molecular masses. The disperse iron oxides are enriched in a sulfur-containing phase. The conversion degree of the compounds increases as the duration of the experiment increases, which indicates that the disperse iron compounds participate multiple times in the cleavage of chemical bonds. Results of Mossbauer spectroscopy indicate that maghemite is reduced to magnetite when the iron oxides react with water vapor during the catalytic aquathermolysis of crude oil at 250°C

Investigation of Structural-Phase Conversion of an Iron-Containing Catalyst by Mössbauer Spectroscopy (Part 2)

The active form of an iron-containing catalyst, an Fe(II, III) mixed oxide, was studied by Mössbauer spectroscopy in order to identify the mechanism of formation of catalysts used for upgrading of heavy oil from Ashalchinsk field. The iron-oxide phase participates in the formation process by breaking carbon–heteroatom bonds in high-molecular-mass components (resins and asphaltenes) of heavy oil and reduces their molecular mass. Thus, the disperse iron oxides are enriched in a sulfur-containing phase. Mathematical processing of Mössbauer spectra obtained during the experiment was used to study the quantitative composition of the products of thermocatalytic action at 300°C. Magnetite (Fe3O4), greigite (Fe3S4), pyrite (FeS2), and pyrrhotite (Fe1–xS) were mainly detected in the isolated catalysts. The magnetite content decreased toward formation of iron sulfides (pyrite and pyrrhotite). Hydrogen sulfide and hydrocarbons were formed as a result of cracking, hydrolysis, and hydrogenolysis reactions at 300°C

Tree state category identification for boreal area conifers using global features estimation by fuzzy logic approach

Определение категорий состояния деревьев позволяет спрогнозировать развитие леса на обследуемом участке. Категории состояния определяются специалистом-лесопатологом на основе субъективных представлений о глобальных признаках обследуемых деревьев. Автоматизация процесса принятия решений по определению категории состояния дерева позволит уйти от субъективности восприятия, повысив тем самым качество проводимых обследований. Для выделения глобальных признаков используется подход на основе нечеткой логики. Аппроксимация функций принадлежности лингвистических переменных выполнена с помощью функций Гаусса. Исследование проведено для деревьев хвойных пород бореальной зоны. Tree state category identification allows forecasting forest development in the surveyed area. Tree state category determination process based on global features is subjective, so its automation will remove this drawback and improve inspections quality. For global features estimation fuzzy logic is used. The spline-approximation of the membership functions of fuzzy sets is made by Gaussian functions. The study was conducted for boreal coniferous trees

Mesoporous iron(Iii)-doped hydroxyapatite nanopowders obtained via iron oxalate

Mesoporous hydroxyapatite (HA) and iron(III)-doped HA (Fe-HA) are attractive materials for biomedical, catalytic, and environmental applications. In the present study, the nanopowders of HA and Fe-HA with a specific surface area up to 194.5 m2 /g were synthesized by a simple precipitation route using iron oxalate as a source of Fe3+ cations. The influence of Fe3+ amount on the phase composition, powders morphology, Brunauer–Emmett–Teller (BET) specific surface area (S), and pore size distribution were investigated, as well as electron paramagnetic resonance and Mössbauer spectroscopy analysis were performed. According to obtained data, the Fe3+ ions were incorporated in the HA lattice, and also amorphous Fe oxides were formed contributed to the gradual increase in the S and pore volume of the powders. The Density Functional Theory calculations supported these findings and revealed Fe3+ inclusion in the crystalline region with the hybridization among Fe-3d and O-2p orbitals and a partly covalent bond formation, whilst the inclusion of Fe oxides assumed crystallinity damage and rather occurred in amorphous regions of HA nanomaterial. In vitro tests based on the MG-63 cell line demonstrated that the introduction of Fe3+ does not cause cytotoxicity and led to the enhanced cytocompatibility of HA

EFFECTIVENESS AND SAFETY OF FAVIPIRAVIR INFUSION IN PATIENTS HOSPITALIZED WITH COVID-19 [ЭФФЕКТИВНОСТЬ И БЕЗОПАСНОСТЬ ИНФУЗИОННОГО ВВЕДЕНИЯ ФАВИПИРАВИРА У ПАЦИЕНТОВ, ГОСПИТАЛИЗИРОВАННЫХ С COVID-19]

Research in the development of new therapeutic agents with a wide spectrum of the antiviral activity and a low ability to develop resistance remains the main dimension in combating the global threat to public health. The need for a parenteral form of favipiravir was dictated by the necessity to increase the efficacy of therapy in COVID-19 inpatients. This dosage form has expanded the possibilities of drug therapy in the inpatients, for whom a therapeutic effect acceleration and a high safety profile of the drugs used are especially important. The aim of the article is the evaluation of the efficacy and safety of a medicinal product containing favipiravir for the parenteral administration against the background of pathogenetic and symptomatic therapy, in comparison with standard therapy in hospitalized COVID-19 patients. Materials and methods. An open, randomized, multicenter comparative study was conducted in 6 research centers in the Russian Federation to evaluate the efficacy and safety of favipiravir, a lyophilisate for the preparation of a concentrate for the infusion solution administrated to the patients hospitalized with COVID-19. Screening procedures and randomization were completed in 217 patients, 209 of which had completed the study in accordance with the protocol. Results. Between the study groups, statistically significant differences have been found out, making it possible to consider the hypothesis of the drug Areplivir (favipiravir) superiority for the parenteral administration over the standard therapy, which included favipiravir (p. o.) and remdesivir. A comparative analysis has shown that a course of therapy with the parenteral favipiravir drug leads to a significant improvement in the condition of patients with COVID-19, significant benefits in terms of the speed and frequency of improvement in the clinical status of patients, as well as a reduction in the hospital stay length. It has been proven that therapy with a drug containing favipiravir for the parenteral administration does not adversely affect the parameters of clinical and biochemical blood tests, urinalysis, coagulograms, vital signs and ECG, which indicates the therapy safety. The study drug is characterized by a high safety profile and tolerability. Conclusion. The versatility and resistance to mutations of RNA-dependent RNA polymerase make it possible to consider it as the main target for combating the most common RNA viruses that cause ARVI, that determines the need further studies of favipiravir to expand the range of its indications. © 2022 Volgograd State Medical University, Pyatigorsk Medical and Pharmaceutical Institute. All rights reserved

Phonon assisted resonant tunnelling and its phonons control

© 2016 Pleiades Publishing, Inc.We observe a series of sharp resonant features in the tunnelling differential conductance of InAs quantum dots. We found that dissipative quantum tunnelling has a strong influence on the operation of nano-devices. Because of such tunnelling the current-voltage characteristics of tunnel contact created between atomic force microscope tip and a surface of InAs/GaAs quantum dots display many interesting peaks. We found that the number, position, and heights of these peaks are associated with the phonon modes involved. To describe the found effect we use a quasi-classical approximation. There the tunnelling current is related to a creation of a dilute instanton-anti-instanton gas. Our experimental data are well described with exactly solvable model where one charged particle is weakly interacting with two promoting phonon modes associated with external medium. We conclude that the characteristics of the tunnel nanoelectronic devices can thus be controlled by a proper choice of phonons existing in materials, which are involved

Phonon assisted resonant tunnelling and its phonons control

© 2016 Pleiades Publishing, Inc.We observe a series of sharp resonant features in the tunnelling differential conductance of InAs quantum dots. We found that dissipative quantum tunnelling has a strong influence on the operation of nano-devices. Because of such tunnelling the current-voltage characteristics of tunnel contact created between atomic force microscope tip and a surface of InAs/GaAs quantum dots display many interesting peaks. We found that the number, position, and heights of these peaks are associated with the phonon modes involved. To describe the found effect we use a quasi-classical approximation. There the tunnelling current is related to a creation of a dilute instanton-anti-instanton gas. Our experimental data are well described with exactly solvable model where one charged particle is weakly interacting with two promoting phonon modes associated with external medium. We conclude that the characteristics of the tunnel nanoelectronic devices can thus be controlled by a proper choice of phonons existing in materials, which are involved