Spin–state transition in the layered barium cobaltite derivatives and their thermoelectric properties

Ba1.9Me0.1Co9O14 (Me = Ba, Sr, Ca) (BCO) layered cobaltites were prepared by means of solid-state reactions method. Crystal structure, microstructure, thermal expansion, electrical conductivity, and thermo-EMF for the obtained oxides were studied; the values of their linear thermal expansion coefficient, activation energy of electrical transport, and power factor values were calculated. It was found that BCO are p-type semiconductors, in which the spin-state transition occurs within 460-700 K temperature interval due to change in spin state of cobalt ions, which accompanied the sharp increase in electrical conductivity, activation energy of electrical conductivity, and linear thermal expansion coefficient, while thermo-EMF coefficient decreased. Partial substitution of barium by strontium or calcium in BCO leads to the increase in spin-state transition temperature and electrical conductivity of the samples, and, at the same time, thermo-EMF coefficient; consequently, their power factor values decrease

Ultrasound Diagnosis and Minimally Invasive Treatment of Posttraumatic Hematomas of the Spleen

The work presents the analysis of ultrasound diagnostic of traumatic hematomas of the spleen in 12 patients after blunt abdominal trauma. Traumatic injuries of large (4 patients) and giant (5 patients) sizes prevailed. Only 3 patients had medium sized traumatic lesion. Ultrasound examination was performed for all patients as a primary procedure and for dynamic observation. We tracked evolution of traumatic spleen injuries and identified four stages of pathological process in case of aseptic development: the stage of “fresh hemorrhage”, the stage of “formed clot”, the stage of “aseptic lysis of the clot”, the stage of “connective tissue organization”. We determined the evidence of pyogenesis of spleen hematomas, identified the stage “bacterial lysis of the clot” and stage of “forming capsules”. We determined the indications and contraindications for the minimally invasive treatment of spleen hematoma. Percutaneous evacuation of the spleen hematoma was performed in all patients. In four cases of minimally invasive treatment was puncture. In one patient the treatment was completed with a single puncture, in 3 patients – with a double one. Drainage of spleen hematomas was performed in 8 patients. We analyzed the results of minimally invasive treatment of traumatic injuries of the spleen under ultrasound control. Minimally invasive treatment was successful in 11 patients. Only 1 patient was operated for post-traumatic aneurysm of the splenic artery due to the continuing bleeding into hematoma

Integrated indicators of the quality of the system as the solution to the problem of separation of useful signal from noisy data

A stable modification of the principal component method is considered, which uses a quantitative estimation of the input data noise – the signal to noise ratio in determining the structure of the principal components and the principal factors for different observationsРассматривается устойчивая модификация метода главных компонент, использующая количественную оценку шума входных данных — отношение сигнал/шум, при определении структуры главных компонент и главных факторов для разных наблюдени

Diagnosis and minimally invasive treatment of complications of acute and chronic pancreatitis with the use of medical imaging (USG, CT and endosonography): literature review

The article describes the modern literature data on the incidence of acute, chronic pancreatitis and its complications. The current classification of complications of acute and chronic pancreatitis. The possibilities of digital diagnostic methods (ultrasonography, computer tomography, endosonography) this pathology. Considered the advantages and disadvantages of these methods of diagnosis. Describes the types of minimally invasive interventions under the control of the means of medical imaging, the indications and contraindications to them, deals with the complications. The selection criteria method of digital diagnosis of complications of acute and chronic pancreatitis and type minimally invasive treatmen

Ultrasound diagnostics of consequences of traumatic injuries of liver

The results of ultrasound diagnostics of consequences of traumatic injuries of liver in 122 patients were analyzed. Contours, structure and. texture of intrahepatic formations depended on the type of tissue substrate (haematoma, haemobylema, bylema), terms of formation and infection of traumatic focus. At aseptic course of haematomas and haemobylemas of liver we divided pathological process into 4 stages: stage of latest hemorrhage, stage of formed clot, hemolytic stage and reparative stage. The differences at the infection way of development started from the second week after appearance of intrahepatic injury on the stage of "bacterial lysis of a clot" and. incapsulation. Ultrasound semiotics of intrahepatic bylemas depended only on the infection of contents

Layered Oxygen-Deficient Double Perovskites as Promising Cathode Materials for Solid Oxide Fuel Cells

Development of new functional materials with improved characteristics for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) is one of the most important tasks of modern materials science. High electrocatalytic activity in oxygen reduction reactions (ORR), chemical and thermomechanical compatibility with solid electrolytes, as well as stability at elevated temperatures are the most important requirements for cathode materials utilized in SOFCs. Layered oxygen-deficient double perovskites possess the complex of the above-mentioned prop-erties, being one of the most promising cathode materials operating at intermediate temperatures. The present review summarizes the data available in the literature concerning crystal structure, thermal, electrotransport-related, and other functional properties (including electrochemical performance in ORR) of these materials. The main emphasis is placed on the state-of-art approaches toimproving the functional characteristics of these complex oxides. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: Dr. A.I. Klyndyuk thanks to the Ministry of Education of Belarus Republic, contract no. 20062703, and to the Belarusian Republican Foundation for Fundamental Research, grant no. C3M–049. Dr. D.A. Medvedev thanks to the Ministry of Education and Science of the Russian Federation, contract no. 075-03-2021-051/5

Разработка композиции на основе полимочевины с увеличенным сроком жизни

Objectives. Improvement of the technology for obtaining polymer-sprayed coatings based on polycarbodiimides (polyureas) with high chemical, hydrolytic, and abrasive resistance and improved physical and mechanical properties, as well as obtainment of polyurea compositions with a lifetime of at least 5 min without loss performance characteristics (i.e., “hand-applied” polyureas) suitable for repair of coatings already in use.Methods. The reaction rate between isocyanate and amino groups is almost a hundred times higher than that between isocyanate and hydroxyl groups, necessitating the use of special highperformance and high-pressure installations equipped with self-cleaning mixing chambers and heating of components. The following are determined from the obtained materials: strength, elongation at break according to the standard method, Taber abrasion, and Shore hardness.Results. Three methods of slowing down the reaction are investigated: 1) the synthesis of prepolymers with the content of NCO groups from 10.5% to 18%; 2) the addition of a plasticizer into the prepolymer in the amount of 1–10 mass parts; and 3) the introduction of polyesters into the composition and radiation of the so-called “hybrid” systems. When using 14% polyesters with a molecular weight of 2000 Da, only “hybrid” systems make it possible to obtain compositions with a lifetime of more than 5 min. At the same time, the tensile strength decreases by 20%, and the abrasion increases by 40%; however, such “hybrid” systems have a higher adhesion force and are cheaper than pure polyureas, allowing them to be used as “repair” systems.Conclusions. The developed composition and technology of applying “hybrid” systems allow for the repair of existing coatings without using specialized devices. “Manual” polyurea is easy to use and does not require special training. Цели. Совершенствование технологии получения полимерных напыляемых покрытий на основе поликарбодиимидов (полимочевин), с высокой химической, гидролитической и абразивной стойкостью и улучшенными физико-механическими показателями, а также, получение полимочевинных композиций с временем жизни не менее 5 мин без потери эксплуатационных характеристик (полимочевин «ручного» нанесения), пригодных для ремонта уже эксплуатирующихся покрытий.Методы. Скорость реакции между изоцианатными и аминогруппами практически в сто раз превышает скорость реакции между изоцианатными и гидроксильными группами, что вызывает необходимость использовать специальные высокопроизводительные установки высокого давления, оснащенные самоочищающимися смесительными камерами и обогревом компонентов. У полученных материалов определяли прочность, удлинение на разрыв по стандартной методике, истираемость по Таберу и твердость по Шору.Результаты. Исследованы три способа замедления реакции: во-первых, синтез предполимеров с содержанием NCO-групп от 10.5% до 18%; во-вторых, введение в предполимер пластификатора в количестве 1–10 масс.ч.; в-третьих, введение в композицию полиэфиров и получения «гибридных» систем. Показано, что только «гибридные» системы при использовании полиэфиров с молекулярной массой 2000 Да, в количестве 14% позволяют получить композиции с временем жизни более 5 мин. При этом прочность на разрыв снижается на 20%, истираемость увеличивается на 40%, но такие «гибридные» системы имеют более высокую силу адгезии и дешевле по сравнению с чистыми полимочевинами, что позволяет использовать их в качестве «ремонтных» систем.Выводы. Разработанный состав и технология нанесения «гибридных» систем позволяют производить ремонтные работы существующих покрытий без применения специализированных устройств. Полимочевина «ручного» нанесения удобна в эксплуатации и не требует специальной подготовки.

Влияние взаимозамещения редкоземельных элементов наструктуру и свойства твердых растворов (Pr, Nd, Sm)BaCoFe5+δ

Using the solid-state reaction method, (Pr,Nd,Sm)BaCoFeO5+δ solid solutions have been synthesized, their lattice constants and oxygen nonstoichiometry have been determined and their thermal expansion and electrical properties have been studied. It has been found that (Pr,Nd,Sm)BaCoFeO5+δ solid solutions show positive deviations from ideality and their structural parameters, thermal and electrotransport properties can be controlled by intersubstitution of rare earth elements in their structure.Твердофазным методом синтезированы твердые растворы (Pr, Nd, Sm)BaCoFeO5+δ, определены параметры их кристаллической структуры и кислородная нестехиометрия, изучены их тепловое расширение и электрические свойства. Установлено, что твердые растворы (Pr, Nd, Sm)BaCoFeO5+δ характеризуются положительными отклонениями от идеальности, а их структурными параметрами, тепловыми и электротранспортными свойствами можно управлять путем направленного взаимозамещения РЗЭ в их структуре

Изотопный состав кислорода и водорода повторно-жильных льдов Центрального Ямала

New data on the distribution of the isotopes δ18О and δD of ice wedges in Central Yamal are presented. In the summer of 2019, the massive wedge ice was studied in the thermal circus of the third marine terrace. On the surface of the terrace, polygonal-vein relief is common with a polygon size of about 10–20 m. The largest ice wedge № 1 in the upper part was 1.5 m wide, and its visible depth in the outcrop amounted to 2.3 m. Perpendicular to this wedge, another one № 2 was opened with a width of 60 cm, and 20 m from them the wedge № 3 was opened along the strike. At the level of the head of the wedge № 1, radiocarbon AMS dating was performed based on a sample of host deposits, which showed that the ice in the upper part was about 13 thousand years old (the ice age was of 13.6 cal. BP). According to the isotopic characteristics (average values of δ18О = −24.8, and δD = −187.6 ‰), the ice corresponds to the Yamal ice-wedge ice, which was formed during the MIS‑2 isotopic stage (the end of the Late Pleistocene). The isotopic composition of oxygen indicates temperatures of the cold period of the vein formation from −22.8 to −26.8 °C (on average 7 °C colder than the present-day) and the January temperatures from −34.2 to −40.2 °C (on average 10 °C colder than the present-day). For some ice samples (11 out of 43), high values of deuterium excesses (dexc = 12÷17 ‰) were observed, which is unusual for this type of ice. A few examples of high dexc values of ice wedges are mentioned in the literature for sections of Seyakha yedoma, Cape Sabler and Bolshoi Lyakhovsky Island, and note that for the ice dated to the Late Pleistocene. The deuterium excess values may reflect the unstable climatic conditions of the Late Pleistocene associated with changes in the vapor source and the trajectories of the air masses over the continent.Приведены новые данные о распределении δ18О и δD в повторно-жильном льду Центрального Ямала. По своим изотопным характеристикам (средние значения δ18О = −24,8, а δD = −187,6 ‰) лёд соответствует жильным льдам Ямала, которые формировались в изотопную стадию МИС‑2 (конец позднего плейстоцена). Для некоторых образцов льда отмечены высокие значения дейтериевого эксцесса (dexc = 12÷17 ‰), что нехарактерно для этого типа льдов. Немногочисленные свидетельства высоких значений dexc в позднеплейстоценовом жильном льду описаны в литературе для раз‑ резов р. Сеяха, мыса Саблера и о. Большой Ляховский