Phase formation and relaxor properties of lead-free perovskite ceramics on the base of sodium-bismuth titanate

The work was supported by the Russian Foundation for Basic Research (Projects 16-53-48009, 17-03-00542)

Effects of boundary conditions on magnetization switching in kinetic Ising models of nanoscale ferromagnets

Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this article we consider the effects of boundary conditions on the switching phenomena. A rich range of behaviors is predicted by droplet theory: the specific mechanism by which switching occurs depends on the structure of the boundary, the particle size, the temperature, and the strength of the applied field. The theory predicts the existence of a peak in the switching field as a function of system size in both systems with periodic boundary conditions and in systems with boundaries. The size of the peak is strongly dependent on the boundary effects. It is generally reduced by open boundary conditions, and in some cases it disappears if the boundaries are too favorable towards nucleation. However, we also demonstrate conditions under which the peak remains discernible. This peak arises as a purely dynamic effect and is not related to the possible existence of multiple domains. We illustrate the predictions of droplet theory by Monte Carlo simulations of two-dimensional Ising systems with various system shapes and boundary conditions.Comment: RevTex, 48 pages, 13 figure

Post-COVID immunopatology syndrome: characteristics of phenotypical changes in the immune system in post-COVID patients

This study examines the long-term effects of SARS-CoV-2 infection on immune status. Given the prolonged and profound immune dysregulation observed during acute SARS-CoV-2 infection, it remains to be determined whether these changes translate into subsequent immune system dysfunction in recovering individuals. In this sense, the aim of the study was to study the parameters of the immune system in patients who had undergone SARS-CoV-2 infection. 150 patients who underwent SARS-CoV-2 infection were examined according to 96 parameters using flow cytometry. A complete blood count was performed using a Medonic device (Sweden); ELISA method determined the levels of general and specific IgM, IgG, IgA, compliment fragments (JSC Vector-Best, Russia). The activity of the phagocytes was studied according to the generally accepted method. The study found that at least four phenotypes of immune system disorders are detected in patients. The first two phenotypes are related to the impairment of innate immune system factors and are associated with a decrease in the number of CD46+ and NK cells. It has been observed that a decrease in CD46+ persists for a long time in a significant number of recovered patients, highlighted by the impaired expression of this marker in various subpopulations of lymphocytes. The decrease in the level of natural killers was accompanied by a compensatory increase in the number of T lymphocytes, mainly due to T helpers and TNK lymphocytes, and the growth of total memory B cells. Two other identified phenotypes are characterized by damage to acquired immune response factors and are associated with damage to B cells and T cytotoxic cells. The relationship of such disorders with damage to hematopoiesis erythrocyte and platelet sprouts, which contribute to the appearance of hypoxia and possible violation of the blood coagulation system, has been shown. Therefore, the results obtained indicate a long-term pronounced damage to the immune system in postCOVID patients that requires immunocorrection of these disorders

Колебательная, релаксационная и трансляционная подвижность ионов Li+ в монокристалле LiNbGeO5.

Dielectric properties of single crystals of LiNbGeO5, crystallizing in the andalusite (β-Al2SiO5) structure, have been studied. Dielectric and conducting properties along the major crystallographic axes were investigated at frequencies from 1 to 1000 kHz and in the range of temperatures between 100 and 600 K. Determined potential barriers between the equilibrium positions of Li+ ions are classified as low energy (0.23-0.79 eV, along the a axis) and high energy (0.9-1.90 eV, along the a, b, and c axes). Additional interstitial sites with the distances between them 0.3-0.4 Å have been found along the a axis, while no such sites observed along the b and c axes. Activation energy (Ea) in the direction a is 0.47 eV and ?a(570 K) = 2.10-5 S/cm, which correspond to the super-ionic conductivity.Исследованы диэлектрические свойства монокристаллов LiNbGeO5 со структурой минерала андалузита (β-Al2SiO5). Диэлектрические и проводящие свойства изучены вдоль главных кристаллографических осей a, b, c при частоте измерительного поля 1-1000 кГц в интервале температур 100-600 К. Найденные значения потенциальных барьеров между положениями равновесия ионов Li+ подразделяются на низкоэнергетические (0.23-0.79 эВ, a-ось) и высокоэнергетические (0.9-1.80 эВ, a, b и c-оси). В направлении оси a обнаружены дополнительные междуузельные позиции с расстояниями между ними 0.3-0.4 A, в то время как для осей b и c такие позиции отсутствуют. В направлении a энергия активации Еa = 0.47 эВ и значение ?a(570 К) = 2.10-5 См/см, что соответствует суперионной проводимости

Определение органных доз внутреннего облучения пациентов при радионуклидной терапии 223Ra -дихлоридом

Radionuclide therapy with 223Ra-dichloride is used to treat bone metastases and to improve the quality of life of patients with metastatic castration-resistant prostate cancer. At the present time there is no reliable data on the biodistribution of the 223Ra-dichloride in the patient body. The aim of this study was to assess absorbed, equivalent doses in radiosensitive organs and tissues and effective dose from internal exposure for patients with metastatic castration-resistant prostate cancer treated with 223Ra-dichloride. Internal doses from 223Ra-dichloride were calculated for a chamber model specific for patients with metastatic castration-resistant prostate cancer. This model consists of 8 chambers (blood plasma, two chambers describing bone tissue, small intestine, upper large intestine, lower large intestine, feces and the rest of the body). Time-integrated activities were calculated using the SAAM II v2.3 software. The IDAC-Dose 2.1 software was used to calculate the absorbed doses. The highest absorbed doses in organs and equivalent doses were determined for the bone surface and red bone marrow. The absorbed dose from a-radiation in the bone surface for a set of six therapeutic procedures with 223Ra-dichloride was estimated as 1 Gy; in the red bone marrow — 0.14 Gy. However, the approach used does not specifically consider accumulation of the radiopharmaceutical in metastases, which can lead to a significant overestimation of the absorbed dose in the healthy part of the bone surface and red bone marrow.Для лечения костных метастазов и улучшения качества жизни пациентов с метастатическим кастрационно-резистентным раком предстательной железы применяют радионуклидную терапию с 223Rа-дихлоридом. Однако в настоящий момент отсутствуют достоверные данные по биораспределению 223Ra-дихлорида в организме пациентов. Целью данной работы являлась оценка поглощенных и эквивалентных доз в радиочувствительных органах и тканях от внутреннего облучения для пациентов с метастатическим кастрационно-резистентным раком предстательной железы при терапии 223Ra-дихлоридом. Дозы внутреннего облучения от 223Ra-дихлорида были рассчитаны для камерной модели пациентов с метастатическим кастрационно-резистентным раком предстательной железы. Данная модель состоит из 8 камер (плазма крови, две камеры, описывающие костную ткань, тонкий кишечник, верхний отдел толстого кишечника, нижний отдел толстого кишечника, кал и остальная часть тела). С использованием программного обеспечения SAAM II v2.3. были рассчитаны интегрированные по времени активности. Для расчета поглощенных доз использовали программное обеспечение IDAC-Dose 2.1. Самые высокие поглощенные дозы в органах и эквивалентные дозы определены для поверхности кости и красного костного мозга. Поглощенная доза от а-излучения в поверхности кости за серию из шести терапевтических процедур с введением 22^а-дихлорид составляет 1 Гр; в красном костном мозге — 0,14 Гр. Однако использованный подход не учитывает специфического накопления радиофармпрепарата в метастазах, что может приводить к значительной переоценке поглощенной дозы в здоровой части поверхности кости и красного костного мозга

Предварительная оценка выведения 225Ac у пациентов, проходящих радионуклидную терапию с 225Ac-DOTA-TATE

The aim of this study was to evaluate the activity of 225Ac in urine of patients undergoing radionuclide therapy with 225Ac-DOTA-TATE. Activity concentration was determined in the urine samples collected within 72 hours after injection of 225Ac-DOTA-TATE, using the ORTEC semiconductor gamma spectrometer, model TSP-DX-100T-PAC-PKG-1. Calculation of excreted activities was additionally performed based on scintig- raphy scans of patients receiving 225Ac-DOTA-TATE. Scans were conducted 5 times for each patient: immedi- ately after injection, at 4 hours, and on the 1st, 2nd, and 3rd days after injection of the radiopharmaceutical. Absolute activity values and fractions of the injected activity were calculated based on the specific activity values. The results of the calculated activity concentration values demonstrate that maximum excretion was observed within the four hours after 225Ac-DOTA-TATE injection. Significant differences between the two methods of determining 225Ac activity were observed only on the third day after radiopharmaceutical injection, which allows for the simplification of future experimental work by using indirect radioactivity measurement methods for activity calculations. There were no significant differences between patient groups with different number of 225Ac-DOTA-TATE injection, which allows for the exclusion of this parameter in the evaluation of experimental results. The results of this study represent the first published experimental data on the determi- nation of actinium excretion in patients.Целью данной работы является оценка активности 225Ac в моче пациентов, проходивших радионуклидную терапию с 225Ac-DOTA-TATE. Удельная активность определялась в пробах мочи, которые отбирались в срок до 72 ч после введения 225Ac-DOTA-TATE с использованием полупроводникового гамма-спектрометра ORTEC, модели TSP-DX-100T-PAC-PKG-1. Также производился расчет выводимых активностей на основании сцинтиграфии пациентов, сканирование осуществляли 5 раз для каждого пациента: сразу после введения, через 4 ч, 1, 2, 3 сут после введения препарата. На основании значений удельных активностей рассчитывались абсолютные значения активностей и проценты от введенной активности. Результаты рассчитанных значений удельных активностей демонстрируют, что максимум выведения наблюдается в первые 4 ч после введения препарата. Статистически значимые различия между 2 методами определения активности 225Ac наблюдались только для 3-х суток после введения препарата, что позволяет в дальнейшем упростить проведение экспериментальных работ, используя методы непрямой радиометрии для расчета активности. Между группами пациентов с разным числом ранее проведенных введений радиофармацевтических лекарственных препаратов отсутствуют статистически значимые различия, что позволяет в дальнейшем не учитывать номер эпизода радионуклидной терапии при оценке результатов экспериментальных работ. Результаты работы являются первыми опубликованными экспериментальными данными по определению выведения 225Ac-DOTA-TATE у пациентов

DETERMINATION OF THE CEMENTED LAYER THICKNESS OF CHROME-NICKEL STEELS

It is shown that the thickness of cemented layer defined after cementation by samples from steel 12Хн3А, is overstated by 0,20–0,35 mm because of higher content of nickel

CHOICE OF STEEL GRADE FOR HIGHLY­STRESSED WHEEL GEARS OF TRANSMISSIONS OF MOTOR AND TRACTOR EQUIPMENT BY CRITERION OF CEMENTED LAYER HARDENABILITY

On a condition of equality of speeds of cooling conformity between distance from a face surface of the tempered face sample and the module of gears for different areas of section of a tooth is established. It is shown, that on the basis of the received dependence with use of diagrammes hardenability of carburized layers and a core of concrete mark of a steel the proved choice of the material providing set quality indicators of chemical heat treatment of gears is carried out