Chronopotentiometry at platinum electrode in KF-NaF-AlF3-Al2O3 melt

Some features of the mechanism of the anode process on platinum in KF–NaF–AlF3–Al2O3 melt at 750–780 °C depending on the of anodic current density (0.5 mA/cm2 to 2.0 A/cm2) and anodic pulse duration have been studied using chronopotentiometry method. In curves of change in the platinum anode potential a small peak at current densities of 10–30 mA/cm2 and a clear peak at current densities of 0.5–2.0 A/cm2 are recorded when the current is cut on. Analysis of dependencies of the transition time on the current density indicates that the first peak in curve is associated with the formation of an oxide compound on the platinum surface, and the second one is related to hindering the diffusion for delivery of electroactive particles to its surface.The study was supported by the Russian Foundation for Basic Research (grant № 13–03–00829 A)

Molecular dynamics study of the stability of aluminium coatings on iron

Among the available protection systems for steel, the use of coatings is the most popular and economical method. One can protect the steel electrode from aggressive media with an aluminum coating. A thin Al film on an Fe substrate has been studied by the molecular dynamics method at a heating temperature from 300 K to 1500 K. A significant horizontal displacement of individual Al atoms on the edges of the film is observed during the simulation. The film begins to “spread” slightly near the edges. This “spreading” creates the conditions for the beginning of diffusion of iron atoms into aluminum. Some Al atoms were found to penetrate the Fe matrix at a temperature of 873 K. The total energy curve of the system shows both the melting transition in aluminum and phase transition from the body-centered cubic lattice to the face-centered cubic one at 1173 K. The binding energy for the Al atom in the lattice of the Fe crystal is smaller than that for Fe atoms. The calculated diffusion coefficients for Al and Fe have a significantly slower growth with a temperature in the range of 673 K ≤ T ≤1500 K. To describe the diffusion in a crystal using the molecular dynamics model, a temperature-dependent correction to the activation energy is calculated. The temperature dependence of the diffusion coefficient of aluminum atoms in an iron crystal can be represented as an Arrhenius expression with a temperature-dependent energy barrier for diffusion. © 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved

АНАЛІЗ ДІАГНОСТИЧНИХ ПАРАМЕТРІВ ІМУНОБЛОТИНГУ РІЗНИХ ВИРОБНИКІВ ДЛЯ ВИЗНАЧЕННЯ СЕНСИБІЛІЗАЦІЇ ДО ПИЛКОВИХ АЛЕРГЕНІВ У ПАЦІЄНТІВ ІЗ РЕСПІРАТОРНИМИ АЛЕРГІЧНИМИ ЗАХВОРЮВАННЯМИ

In the context of the large amount of sometimes unfair information, the physician is not always able to understand the advantages and disadvantages of each method and correctly evaluate the parameters of their diagnostic value. The aim of the study – to compare the diagnostic parameters of different systems of serological examination by immunoblot method for the determination of sensitization to allergens of pollen group in patients with respiratory allergic diseases – allergic rhinitis and bronchial asthma. Materials and Methods. In the study, 88 patients with allergic rhinitis and/or atopic asthma were examined with three different methods of specific allergic diagnosis (in vivo and in vitro). Inclusion criteria were a diagnosis of allergic rhinitis (both intermittent and persistent) and/or atopic asthma. The prick test was conducted according to the classic test method according to the normative documents with commercial allergen extracts.  Western blots for the determination of IgE levels were performed using RIDA AllergyScreen test systems (R-Biopharm AG, Darmstadt, Germany) and Euroline (Euroimmun). Results. The results of two systems for determining specific IgE for pollen allergens by the Rida AllergyScreen and Euroline methods do not always agree very well due to the systematic divergence of indicators. The results of determining specific IgE for individual allergens are generally in good agreement with each other and the results of skin testing by the prick test, however, for wormwood, birch, hazel and alder pollen allergens, the Euroline system does not always match the results of skin testing by the prick test negative results. Conclusions. Further analysis of the consistency and diagnostic parameters of the methods for other allergen groups is necessary to summarize all the results of the study.В умовах великого обсягу іноді заангажованої інформації лікар не завжди здатний зрозуміти переваги та недоліки кожного з методів та правильно оцінити параметри їх діагностичної цінності. Мета дослідження – порівняти діагностичні параметри різних систем серологічного дослідження методом імуноблоту для визначення сенсибілізації до алергенів пилкової групи у пацієнтів із респіраторними алергічними захворюваннями – алергічним ринітом та бронхіальною астмою. Матеріали і методи. У ході дослідження обстежено 88 пацієнтів з алергічним ринітом та/або атопічною астмою за допомогою трьох різних методів специфічної алергічної діагностики (in vivo та in vitro). Критеріями включення були діагноз алергічного риніту (як інтермітуючого, так і персистуючого) та/або атопічної астми. Прик-тест проводили за класичною методикою тестування відповідно до нормативних документів із комерційними екстрактами алергенів. Вестерн-блот для визначення рівнів IgE виконували з використанням тест-систем RIDA AllergyScreen (R-Biopharm AG, Дармштадт, Німеччина) і Euroline (Euroimmun). Результати. Результати двох систем визначення специфічного IgE до алергенів пилкової групи методами Rida AllergyScreen та Euroline не завжди дуже добре узгоджуються між собою унаслідок систематичного розходження показників. Результати визначення специфічних IgE до окремих алергенів у цілому добре узгоджуються між собою та результатами шкірного тестування методом прик-тесту, втім до пилкових алергенів полину, берези, ліщини та вільхи система Euroline не завджи узгоджується з результатами шкірного тестування методом прик-тесту, даючи хибно-негативні результати. Висновки. Подальший аналіз узгодження та діагностичних параметрів методів в інших групах алергенів є необхідним для узагальнення усіх результатів дослідження

Heat of Fusion of Na3AlF6 Eutectic Mixtures with CaF2 and Al2O3

The heat of fusion of eutectic mixtures of sodium cryolite with alumina and calcium fluoride was measured using differential scanning calorimetry. Melting temperatures were found to be in good agreement with literature data. The molar heat of fusion of cryolite salts and eutectic mixtures was found to be directly dependent on melting temperature. The temperature dependence coefficient is the same as that of alkali halides

SYNTHESIS OF TANTAL POWDERS BY SECONDARY REDUCTION IN KCL–NACL MELTS

The work was carried out with the financial support of the UrB RAS Program 2015-2017. "Materials and technologies for nuclear, alternative and renewable energy" (Project No. 15-20-3-20)

High-Temperature Electrochemistry of Calcium

Received: 12 July 2022. Accepted: 03 September 2022.Electrolytically produced calcium is one of the most demanded materials in obtaining pure materials. At the same time, the existing technologies and devices for the electrolytic production of calcium were developed in the last century, and at present there are practically no works aimed at optimizing them. However, increasing the capacity and efficiency of existing devices for the production of calcium is in demand. To analyze possible ways to improve calcium production, a comprehensive understanding of the processes occurring at the electrodes and in the electrolyte during electrolytic production of calcium is required. This review briefly outlines the main points concerning the electrolytic production of calcium: from a brief history of the development of methods for the electrolytic production of calcium and established ideas about its physicochemical processes to information about new developments using the electrolysis of CaCl2-based melts. Review content: brief history of process development; base electrolyte for calcium production, including preparation of CaCl2 and influence of additions on it physicochemical properties; data on calcium solubility in CaCl2; information about alternative electrolytes for calcium production; short description of electrode processes in the CaCl2-based melts; proposed technologies and devices for the electrolytic production of calcium

Towards the stability of low-temperature aluminum electrolysis

The results of several different tests related to the low-temperature aluminum electrolysis were considered in this work. The role of mass transfer processes in the anode-cathode space was recommended to be significant during electrolysis in the low-temperature KF-AlF3 and NaF-AlF3-based melts. The stationary polarization and voltammetry methods were applied in order to study the kinetics of the electrode processes on the carbon and metal electrodes in the KF-AlF3-Al2O3 melts and to select the electrolysis parameters. The schemes of electrode processes were suggested on the basis of electrochemical tests, the flows of substances in the anode-cathode distance were analyzed and the main reasons of the cathode current efficiency decrease during the low-temperature electrolysis in the KF-AlF3-Al2O3 and KF-NaF-AlF3-Al2O3 melts were discussed. It was revealed that the cathode current density should not exceed 0.4-0.55 A cm-2 during the electrolysis at 750 °C-800 °C. © 2021 The Author(s).U.S. Department of Energy, USDOENational Renewable Energy Laboratory, NRELMinistry of Education and Science of the Russian Federation, Minobrnauka, (FEUZ-2022-0031)Funding text 1: The research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) is gratefully acknowledged. The youth laboratory with Grant number: FEUZ-2022-0031.Funding text 2: The modelling of the CSP was performed using SAM version 2020.2.29, provided by the National Renewable Energy Laboratory (NREL), funded by the Department of Energy. SAM is commonly used by researchers for techno-assessment analysis worldwide. The SAM model also includes the simulation of the parabolic trough, power tower, and linear Fresnel for electric power generation []. In this present investigation, a solar tower power plant is modeled in India. The flow diagram of the simulation in the SAM software is presented in

Анодный процесс на платине в расплаве на основе CaCl2-CaO

Methods potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic processes on platinum in the molten CaCl2-KCl-CaO when 725–775 °C. Given thermodynamic values of potential difference probable total reactions in the range of the studied temperature. Using potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic process on platinum in the molten CaCl2-KCl-CaO when 725–775 °C thermodynamic assessment of the probability of occurrence total reactions during electrolysis melt on the basis of CaCl2-CaO using non-carbon anode. It is shown that at high current densities anodic process takes place mainly in the conditions of slow diffusion of electrically active particles to the anode, and at low densities (up to 10 mA/cm2) to their discharge to the atomic and lecular oxygen is preceded by a stage, which can be associated with adsorption of atoms of oxygen or with the formation of an oxide film on the surface of platinum. To detect the nature of this stage, further research is needed.Методами потенциостатической поляризации и циклической вольтамперометрии получены новые экспериментальные данные о механизме и кинетике анодных процессов на платине в расплаве CaCl2-KCl-CaO при 725–775 °С. Приведены термодинамические значения разности потенциалов вероятных суммарных реакций в диапазоне исследуемых температур. При помощи потенциостатической поляризации и циклической вольтамперометрии получены новые экспериментальные данные относительно механизма и кинетики анодного процесса на платине в расплаве CaCl2-KCl-CaO при 725–775 °С. Проведены термодинамические оценки вероятности протекания суммарных реакций при электролизе расплава на основе CaCl2-CaO с использованием неуглеродного анода. Показано, что при высоких плотностях тока анодный процесс протекает преимущественно в условиях замедленной диффузии электроактивных частиц к аноду, а при низких плотностях (до 10 мА/см2) их разряду до атомарного и молекулярного кислорода предшествует стадия, которая может быть связана с адсорбцией атомов кислорода или с образованием оксидной пленки на поверхности платины. Для установления природы этой стадии необходимы дальнейшие исследования

Anode process on platinum in CaCl2-CaO-based melt

Methods potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic processes on platinum in the molten CaCl2-KCl-CaO when 725–775 °C. Given thermodynamic values of potential difference probable total reactions in the range of the studied temperature. Using potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic process on platinum in the molten CaCl2-KCl-CaO when 725–775 °C thermodynamic assessment of the probability of occurrence total reactions during electrolysis melt on the basis of CaCl2-CaO using non-carbon anode. It is shown that at high current densities anodic process takes place mainly in the conditions of slow diffusion of electrically active particles to the anode, and at low densities (up to 10 mA/cm2) to their discharge to the atomic and lecular oxygen is preceded by a stage, which can be associated with adsorption of atoms of oxygen or with the formation of an oxide film on the surface of platinum. To detect the nature of this stage, further research is needed

Anode Processes on Pt and Ceramic Anodes in Chloride and Oxide-Chloride Melts

Platinum anodes are widely used for metal oxides reduction in LiCl–Li2O, however high-cost and low-corrosion resistance hinder their implementation. NiO–Li2O ceramics is an alternative corrosion resistant anode material. Anode processes on platinum and NiO–Li2O ceramics were studied in (80 mol.%)LiCl-(20mol.%)KCl and (80 mol.%)LiCl-(20 mol.%)KCl–Li2O melts by cyclic voltammetry, potentiostatic and galvanostatic electrolysis. Experiments performed in the LiCl–KCl melt without Li2O illustrate that a Pt anode dissolution causes the Pt2+ ions formation at 3.14 V and 550°С and at 3.04 V and 650оС. A two-stage Pt oxidation was observed in the melts with the Li2O at 2.40 ÷ 2.43 V, which resulted in the Li2PtO3 formation. Oxygen current efficiency of the Pt anode at 2.8 V and 650°С reached about 96%. The anode process on the NiO–Li2O electrode in the LiCl–KCl melt without Li2O proceeds at the potentials more positive than 3.1 V and results in the electrochemical decomposition of ceramic electrode to NiO and O2. Oxygen current efficiency on NiO–Li2O is close to 100%. The NiO–Li2O ceramic anode demonstrated good electrochemical characteristics during the galvanostatic electrolysis at 0.25 A/cm2 for 35 h and may be successfully used for pyrochemical treating of spent nuclear fuel. © 2021 Korean Nuclear Society.The present research was partially performed within the Proryv (Breakthrough) project of State Atomic Energy Corporation Rosatom