Viscosity of fluoride melts promising for molten salt nuclear reactors

The viscosity of molten salt, as an important hydrodynamic property, should be taken into account when creating and operating molten salt nuclear reactors (MSRs). An eutectic FLiNaK is considered to be one of the most suitable for use in MSR designed for the minor actinides transmutation. The dynamic viscosity of the molten mixtures FLiNaK + NdF3, FLiNaK + CeF3 and FLiNaK + LaF3 was measured in a temperature range of 600–700 °C using the high-temperature rotary rheometer FRS-1600. Lanthanide fluorides were considered as analogues of actinide fluorides. It was revealed that the additions of rare earth fluorides (REM)F3 in amount of 15 mol. % significantly impact the viscosity of the system FLiNaK + (REM)F3,but the effect of NdF3, CeF3 and LaF3 was found to be almost the same. In order to calculate the kinematic viscosity of the molten mixture FLiNaK + NdF3, a regression equation depending on several parameters was derived. This model equation can be used for predicting the kinematic viscosity of molten mixtures of FLiNaK with other rare earth fluorides.https://doi.org/10.15826/elmattech.2023.2.02

Effect of Al2O3 and CaF2 additives on the viscosity of conventional cryolite melts

The viscosity of cryolite melts of conventional composition NaF–AlF3–CaF2–Al2O3 was studied by rotational viscometry using the FRS 1600 high-temperature rheometer. The cryolite ratio of the NaF–AlF3 melt was 2.1, 2.3, and 2.5; the Al2O3 content varied from 2 to 6.6, and CaF2 – from 0 to 8 wt%. The measurements were carried out in the temperature range from liquidus to 1200 °C. The conditions for the laminar flow of the investigated melts were determined, based on the measurements of the cryolite melts viscosity as a function of the shear rate at a constant temperature. A shear rate of 12 ± 1 s–1 was chosen for studying the viscosity temperature dependence for all samples. The viscosity temperature dependence of cryolite melts is described by a linear equation. The temperature coefficient b in this equation has negative values and varies in the range of (–0.01)–(–0.06) mPa·s/deg. It was found that the viscosity of cryolite melts of conventional composition in the range of operating temperatures of aluminum electrolysis (950–970 °C) varies from 2.5 to 3.7 mPa·s (depending on the composition and temperature). The viscosity of cryolite-alumina melts increases with the rise of alumina content: 1 wt% Al2O3 increases the viscosity, on average, by 1%. However, the influence of CaF2 is more significant: the addition of 1 wt% CaF2 leads to an increase in viscosity by 3%. A decrease in the CR of the melt by 0.1 (in the range of 2.1–2.5) leads to a decrease in the viscosity of cryolite melts by 2.3%. A viscosity regression equation for the cryolite melts of conventional composition as a function of several independent parameters (temperature, CR, CaF2 and Al2O3 content) is obtained by the multivariable approximation of experimental data. The equation satisfactorily (within 1.5%) describes the viscosity of conventional industrial electrolytes and can be used for estimation of their viscosity

Borated graphite cathodes for low-temperature aluminum electrolysis

Electrochemical boriding of the graphite plates in the potassium cryolite based electrolytes was studied. The boriding were carried out in a cell with vertical electrodes. The procedure included 2 stages: 1) electrolysis in the KF–AlF3–KBF4 melt (CR=1.3) at low current density (0.01–0.02 A/cm2), required for the boron reduction, at 700 and 750 °C; 2) electrolysis in the KF–AlF3–Al2O3 melt at higher current density (0.2 A/cm2), required for the aluminum reduction. The optimal conditions of electrodeposition for obtaining the borated wettable cathodes were determined. According to the SEM data, a continuous AlB2 layer with a thickness of 7–10 μm was formed on the graphite surface. The borated graphite was tested as a wetted cathode during the low-temperature aluminum electrolysis. Prolonged electrolysis in a vertical cell with the graphite anode and the borated graphite cathode was carried out in the KF–NaF(10 wt.%)–AlF3–Al2O3 electrolyte (CR=1.5) at 830 °C. After 100 h of electrolysis, the thickness of the AlB2 layer on the graphite surface was 5 μm, while the cathode surface was completely wetted with aluminum. Thus, we demonstrated the feasibility of using the borated graphite cathode as a wettable dripping cathode in the low-temperature aluminum electrolysis in the vertical cell

Malnutrition as a factor aggravating the heart failure course in the elderly and senile age

Cardiovascular diseases are the main death causes in the modern world. Heart failure (HF) is the terminal stage of most cardiovascular diseases. The prevalence of HF is increasing in patients of older age groups. At the same time, the number of geriatric syndromes increases with age, one of which is malnutrition. Recent studies demonstrate the mutually aggravating effect of heart failure and malnutrition, and that the correction of malnutrition can improve the heart failure course. The introduction of screening and timely correction of malnutrition will reduce the hospitalization and mortality rates in geriatric patients with HF

Опыт применения онлайн-технологий в транспортном образовании

The objective of this article is to identify pedagogical technologies traditionally used in full-time education, which found their place when educational formats changed in the era of digital transformation. The discussion concerns the project method, the case method, the analysis of the digital footprint, the use of game teaching methods, virtual laboratory work, various types of Internet testing, methods of collective search for a solution to the problem. The application of the considered methods in learning the Physics as a discipline at Moscow Automobile and Road Construction State Technical University (MADI) constituted the empirical basis of the study.The design method turned to be the most effective and developed one. Its application made it possible to organise participation of students of 1–2 years of study in educational and research work under the guidance of lecturers who are related to physics and the chosen fields of training at MADI. It is shown that as a result, students acquire the skills to search and select the necessary information, learn to complete project work on time, prepare presentations, write scientific texts both for presenting them as oral reports and as texts of scientific articles. Possibilities of using electronic registers are described, in which both attendance at classes and performance of tasks are recorded, and the time factor (indication on whether the work was completed on time or was late) is considered. The article studies the use of a point-rating system to control current assignments, and also provides description of developments by the teaching staff of the department on organisation of an oral exam and test in physics in an online format.Целью настоящей статьи является выявление педагогических технологий, традиционно применявшихся в очном формате обучения, которые нашли своё место при изменении образовательных форматов в эпоху цифровой трансформации. Обсуждаются проектный метод, кейс-метод, анализ цифрового следа, использование игровых методик обучения, виртуальные лабораторные работы, различные виды Интернет-тестирования, методы коллективного поиска решения проблемы. Эмпирической основой исследования стало использование рассмотренных методов в учебном процессе по дисциплине «Физика» в Московском автомобильно-дорожном государственном техническом университете (МАДИ), в том числе с учётом перехода на дистанционные формы обучения в период пандемии.Самым эффективным и разработанным методом оказался проектный метод. Его применение позволило организовать участие обучающихся 1–2 курсов в учебно исследовательских работах под руководством преподавателей, которые связаны с физикой и выбранным направлением подготовки в МАДИ. Показано, что в результате студенты приобретают навыки поиска и отбора необходимой информации, учатся выполнять проектные работы в срок, готовить презентации, писать научные тексты как для произнесения их в качестве докладов, так и в качестве текстов научных статей. Приведены возможности использования электронных журналов, в которых фиксируются и посещение занятий, и выполнение заданий, причём принимается во внимание временной фактор (вовремя сдал работу или опоздал). Рассмотрено применение балльно-рейтинговой системы для контроля текущих заданий, а также приведены разработки преподавателей кафедры по организации устного экзамена и зачёта по физике в онлайн-формате

EFFICACY AND SAFETY OF LIPID-LOWERING DRUGS IN PRIMARY AND SECONDARY PREVENTION OF CARDIOVASCULAR DISEASES IN THE ELDERLY

Effect of hyperlipidemia on morbidity and mortality in elderly patients is considered. Authors also cover issues of efficacy and safety of lipid-lowering therapy in primary and secondary prevention of cardiovascular diseases in patients ≥80 years of age who are the most quickly growing group of population and have the highest cardiovascular risk. They stress the need to take into account polymorbidity and polypharmacy that increase the risk of adverse reactions due to the use of both statins and their drug-drug interactions, which requires an assessment of risk/benefit ratio. In addition, there is a need for development of reliable prognostic tools to predict relevant outcomes (e.g., stroke, decrease in functionality/independence, quality of life reduction) and rationales for lipid-lowering therapy in the elderly and also their adherence to treatment

Features of pharmacotherapy in the elderly patients. Introduction to the problem

Features of pharmacotherapy in the elderly patients are discussed. Data on the pharmacokinetics and pharmacodynamics, comorbidity, polypragmasy and treatment adherence among patients of this age group are presented

Studying radiation hardness of a cadmium tungstate crystal based radiation detector

The given article considers radiation hardness of an X-ray detector used in production of non-destructive testing instruments and inspection systems. In the course of research, experiments were carried out to estimate radiation hardness of a detector based on cadmium tungstate crystal and its structural components individually. The article describes a layout of an experimental facility that was used for measurements of radiation hardness. The radiation dose dependence of the photodiode current is presented, when it is excited by a light flux of a scintillator or by an external light source. Experiments were carried out to estimate radiation hardness of two types of optical glue used in detector production; they are based on silicon rubber and epoxy. With the help of a spectrophotometer and cobalt gun, each of the glue samples was measured for a relative light transmission factor with different wavelengths, depending on the radiation dose. The obtained data are presented in a comprehensive analysis of the results. It was determined, which of the glue samples is most suitable for production of detectors working under exposure to strong radiation

Получение лигатуры Al–B алюмотермическим восстановлением KBF4и B2O3 в среде расплавленных солевых флюсов

The study covers the process of obtaining the Al–B master alloy by the KBF4and B2O3aluminothermic reduction using KF–AlF3and KF–NaF–AlF3fluoride fluxes at 983 and 1123 К, respectively, and KCl–NaCl–KF chloride-fluoride fluxes at Т= 1173÷1223 К. All experiments were carried out under the same conditions: molten mixture stirring rate was 400 rpm, synthesis duration was 30min. The maximum amount of boron (1,5 %) in the Al–B alloy was obtained when using KBF4(3 % per B) as a boron-containing raw material in the KF–AlF3medium with a molar (cryolite) ratio (CR) of KF/AlF3equal to 1,3, atТ= 983 К, while boron recovery ratio did not exceed 75 %. Comparable results were obtained in experiments with KF–NaF–AlF3f lux (CR = 1,5) at Т= 1123 К. However, with the increased concentration of fed boron its recovery ratio decreased substantially. It is connected with the higher decomposition temperature of not only KBF4, but also less thermally stable NaBF4 formed as a result of exchange reaction in the melt. Therefore it is not recommended to use sodium salts as a f lux component. The Al–B master alloys obtained by KBF4reduction in fluoride fluxes were solid solutions of B in Al containing the AlB2intermetallic compound. The lowest amount of boron in aluminum with the minimum degree of extraction was obtained in experiments with the B2O3in molten KF–AlF3with CR = 1,5. Nevertheless, the results of scanning electron microscopy indicate a uniform distribution of B over the Al matrix and the absence of intermetallic compounds, while a large amount of Al2O3was found, which is the product of B2O3reactions with both liquid Al and KF–AlF3flux.Исследован процесс получения лигатуры Al–B методом алюмотермического восстановления KBF4и B2O3с использованием фторидных флюсов KF–AlF3и КF–NaF–AlF3при температурах, соответственно, 983 и 1123 К и хлоридно-фторидных флюсов KCl–NaCl–KF при Т= 1173÷1223 К. Все эксперименты проводили при одинаковых условиях: скорость перемешивания расплавленной смеси – 400 об/мин, длительность синтеза – 30 мин. Максимальное количество бора (1,5 %) в сплаве Al–B было получено в случае применения в качестве борсодержащего сырья KBF4(3 % в расчете на В) в среде KF–AlF3с мольным (криолитовым) отношением (КО) компонентов KF/AlF3, равным 1,3, при Т= 983 К, при этом степень извлечения бора не превышала 75 %. Сравнимые результаты были получены в экспериментах с флюсом KF–NaF–AlF3(КО = 1,5) при Т= 1123 К. Однако при увеличении концентрации задаваемого бора степень его извлечения существенно снижалась, что связано с разложением при более высокой температуре не только KBF4, но и менее термически устойчивого NaBF4, который образуется в результате обменной реакции в расплаве. Поэтому не рекомендуется использование солей натрия в качестве компонента флюса. Лигатуры Al–B, полученные восстановлением KBF4в среде фторидных флюсов, представляли собой твердые растворы бора в алюминии, содержащие интерметаллид AlB2. Наименьшее количество бора в алюминии с минимальной степенью извлечения было получено в опытах с B2O3в среде расплавленного KF–AlF3с КО = 1,5. Тем не менее результаты сканирующей электронной микроскопии свидетельствуют о равномерном распре-делении B в матрице Al и отсутствии интерметаллидов, при этом найдено большое количество оксида Al2O3, который является продуктом реакций B2O3как с жидким Al, так и с флюсом KF–AlF3

LIPID-LOWERING THERAPY IN OUTPATIENT PRACTICE (ACCORDING TO THE ARGO-2 STUDY)

Aim. To study the features of lipid-lowering therapy with rosuvastatin in high and very high cardiovascular risk patients in real outpatient practice.Material and methods. Patients ≥30 years, visited internists or cardiologists of district outpatient clinics in the period from October 2013 to July 2014 were included into the study. Each patient fill in questionnaire. Determination of total cholesterol (TC) level was performed without special preparation of the patient using a portable photometric blood analyzer. Doctors prescribed rosuvastatin therapy when indicated, in accordance with the Guidelines, choosing the dose on their own. Repeated TC level was determined after 1 month.Results. TC level was initially determined in 10547 patients. Rosuvastatin treatment was recommended for all patients. Repeated TC level determination was performed in 7897 patients in an average after 33 days. Baseline TC level in them was 6.37±0.89 mmol/l, and after 1 month while taking rosuvastatin – 4.89±0.81 mmol/l (p<0.001). The change of TC level was -22% (p<0.001). The average prescribed dose of rosuvastatin was 11.88±5.1 mg per day. The most often (62.8%) rosuvastatin was prescribed in a dose of 10 mg per day, in 27.3% of patients – 20 mg per day, in 9.2% – 5 mg per day, and only 0.5% of patients took it in the maximal dose.Conclusion. In real clinical practice, rosuvastatin for treatment of patients with high or very high cardiovascular risk is often prescribed in moderate doses and rarely in the maximum dose despite the proven lipid-lowering effect