526 research outputs found

    Ultrafast hot-carrier dynamics in ultrathin monocrystalline gold

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    Applications in photodetection, photochemistry, and active metamaterials and metasurfaces require fundamental understanding of ultrafast nonthermal and thermal electron processes in metallic nanosystems. Significant progress has been recently achieved in synthesis and investigation of low-loss monocrystalline gold, opening up opportunities for its use in ultrathin nanophotonic architectures. Here, we reveal fundamental differences in hot-electron thermalisation dynamics between monocrystalline and polycrystalline ultrathin (down to 10 nm thickness) gold films. Comparison of weak and strong excitation regimes showcases a counterintuitive unique interplay between thermalised and non-thermalised electron dynamics in mesoscopic gold with the important influence of the X-point interband transitions on the intraband electron relaxation. We also experimentally demonstrate the effect of hot-electron transfer into a substrate and the substrate thermal properties on electron-electron and electron-phonon scattering in ultrathin films. The hot-electron injection efficiency from monocrystalline gold into TiO2, approaching 9% is measured, close to the theoretical limit. These experimental and modelling results reveal the important role of crystallinity and interfaces on the microscopic electronic processes important in numerous applications

    Disruption of the dopaminergic system in the pathophysiology of diabetes mellitus

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    The aim of this work was to conduct an analytical literature review assessing the state of the problem of dopaminergic dysfunction in diabetes from a pathophysiological perspective.Цель работы – провести аналитический обзор литературы с оценкой состояния проблемы нарушения дофаминергической системы при СД с патофизиологических позиций

    University Environment in Student Assessments: Case of the Russian University of Transport

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    The university environment includes various material and intangible aspects that are subjected now to active changes associated with both the development of information tech-nology and the new needs of young people. Therefore, the attitude of students to their university environment is an actual research topic. The Russian University of Transport (RUT (MIIT)) conducted the online survey of students, during which they were asked an open question regarding university problems and university development. The results showed that the problems associated with communication and mutual understanding, taking into account their opinions and interests, are of the greatest importance for modern students. The wishes of the students to the teaching staff were expressed, from which it is required both the ability to clearly explain the subject, and the presence of an individual and respectful approach to each student. We should not forget about the need of modern students in obtaining practice-oriented modern knowledge and skills, often associated with the need to rejuvenate teaching staff. Attention is paid to aspects related to improving the infrastructure of the university, the educational process. The problems related to the extracurricular scientific and educational life of the university, cultural and sports activities, environmental issues, schedule and mode of classes, work of educational departments are disclosed. The development of political education and patriotism in the university depends on small but effective events and the presence of an organizing groups. The novelty of the obtained data is due to the fact that the answers to an open question always differ from the opinions received in the course of polls with pre-proposed answers, and make it possible to identify hidden trends in public opinion. Respondents, in this case, express what worries them first of all, express the wishes that come to mind first, without prompts. The findings indicate the need to develop a strategy for improving the educational environment of the university, aimed at developing the possibilities of direct communication, increasing informal, understanding interactions

    Акустическая методика регистрации начальной скорости деформирования при высокоскоростной штамповке стержневых изделий

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    An acoustic methodology  has been developed and expression have been obtained for determining the initial deformation rate v0 during high-speed forging of rod products. The most rational layout of the recording device relative tothe installation elements has been established while using the obtained expressions. The essence of the developed technique lies in recording, using a recording device, sound waves generated during the departure of the impactor from the shaft of the installation and its further collision with the shaping punch, followed by finding the time ∆t during which the impactor travels the distance L between two known points of its trajectory. In turn, the value ∆t is defined as the difference between the recording time of the sound wave generated by the departure of the impactor from the shaft of the installation, and the recording time of the sound wave generated by the collision of the impactor with the shaping punch. The initial deformation rate, registered using the developed technique during the implementation of the process of high-speed forging of rod products, was v0 = 115.46 m/s.Разработана акустическая методика и получены выражения для определения начальной скорости деформирования v0 при высокоскоростной штамповке стержневых изделий, позволяющие найти наиболее рациональную схему расположения записывающего устройства относительно элементов установки. Сущность разработанной методики заключается в регистрации с помощью записывающего устройства звуковых волн, образующихся в процессе вылета ударника из ствола установки и его дальнейшего соударения с формообразующим пуансоном с последующим нахождением времени ∆t, за которое ударник проходит расстояние между двумя известными точками своей траектории. В свою очередь, величина ∆t определяется как разность между временем регистрации звуковой волны, образовавшейся от вылета ударника из ствола установки, и временем регистрации звуковой волны, образовавшейся от соударения ударника с формообразующим пуансоном. Начальная скорость деформирования, зарегистрированная с помощью разработанной методики в ходе реализации процесса высокоскоростной штамповки стержневых изделий, составила v0 = 115,46 м/с

    ZnO Particles Stabilized in Polymeric Matrix for Liquid-Phase Methanol Synthesis

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    ZnO supported on hypercrosslinked polystyrene was developed for liquid-phase methanol synthesis. The synthesized catalyst was characterized using the low-temperature nitrogen physisorption, TEM, XPS, XAS, and CO DRIFT methods. The analysis showed that the catalyst has a high specific surface area (720 m2/g) and is characterized by the micro-mesoporous structure typical of the polymer used. The active phase is represented by ZnO species with a hexagonal wurtzite structure. ZnO-HPS showed high activity, selectivity, and stability in liquid-phase methanol synthesis in comparison with the industrial catalyst. The activity of the proposed catalyst was found to be 1.64 times higher than that of the conventional Cu/ZnO/Al2O3

    Glutathione peroxidase and superoxide dismutase as markers of brain dysfunction in adolescents with diabetic ketoacidosis

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    Aim: to study the content of antioxidant enzymes in adolescents with type 1 DM in the setting of DKA and determine the correlation between the concentration of glutathione peroxidase (GP) and superoxide dismutase (SOD) and brain dysfunction after the manifestation of DKA.Цель работы − определить содержание АФ у подростков с СД 1 типа на фоне ДКА и установить связь между концентрацией глутатионпероксидазы (ГП), супероксиддисмутазы (СОД) и мозговой дисфункцией после манифестации ДКА

    Highly Selective CO<sub>2</sub> Hydrogenation to Methanol over Complex In/Co Catalysts: Effect of Polymer Frame

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    The growing demand for new energy sources governs the intensive research into CO2 hydrogenation to methanol, a valuable liquid fuel. Recently, indium-based catalysts have shown promise in this reaction, but they are plagued by shortcomings such as structural instability during the reaction and low selectivity. Here, we report a new strategy of controlling the selectivity and stability of bimetallic magnetically recoverable indium-based catalysts deposited onto a solid support. This was accomplished by the introduction of a structural promoter: a branched pyridylphenylene polymer (PPP). The selectivity of methanol formation for this catalyst reached 98.5%, while in the absence of PPP, the catalysts produced a large amount of methane, and the selectivity was about 70.2%. The methanol production rate was higher by a factor of twelve compared to that of a commercial Cu-based catalyst. Along with tuning selectivity, PPP allowed the catalyst to maintain a high stability, enhancing the CO2 sorption capacity and the protection of In against sintering and over-reduction. A careful evaluation of the structure–activity relationships allowed us to balance the catalyst composition with a high level of structural control, providing synergy between the support, magnetic constituent, catalytic species, and the stabilizing polymer layer. We also uncovered the role of each component in the ultimate methanol activity and selectivity

    Treatment of cryptorchidism in pediatric surgical practice: a multicenter study

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    Introduction. Cryptorchidism is a common disease in pediatric urological and andrological practice since the issues of tactical approaches and its optimal treatment remain extremely relevant. Cryptorchidism makes a significant contribution to the structure of male infertility.Objective. To conduct a retrospective analysis of treatment results in children and adolescents with cryptorchidism.Materials &amp; methods. This study summarises the treatment results of 8308 patients with cryptorchidism aged from 6 months to 17 years who underwent inpatient treatment in the Russian Federation and the Republic of Uzbekistan.Results. It was revealed that from 2015 to 2019, patients were admitted for surgical treatment evenly over the years. The ratio of right-sided / left-sided / bilateral cryptorchidism was 4.6 : 4.4 : 1 The inguinal form prevailed more than 6 times over the abdominal location. At the same time, 26.1% of the patients underwent surgery at the optimal time, and 9.8% were older than 10 years. More often, children are operated from an open inguinal access (95.0%), much less often — laparoscopically and percutaneously. Stage-by-stage treatment was carried out in 6.0% of patients.Conclusion. Thus, the approach presented in the study in the surgical treatment of cryptorchidism provided good treatment results. The number of disease relapses was 1.9% (mainly among children over 7 years old). Most surgeons are very reserved about primary orchidectomies (only 3.8% were performed)

    Synthesis of Disubstituted Carboxonium Derivatives of <i>Closo</i>-Decaborate Anion [2,6-B<sub>10</sub>H<sub>8</sub>O<sub>2</sub>CC<sub>6</sub>H<sub>5</sub>]<sup>−</sup>: Theoretical and Experimental Study

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    A comprehensive study focused on the preparation of disubstituted carboxonium derivatives of closo-decaborate anion [2,6-B10H8O2CC6H5]− was carried out. The proposed synthesis of the target product was based on the interaction between the anion [B10H11]− and benzoic acid C6H5COOH. It was shown that the formation of this product proceeds stepwise through the formation of a mono-substituted product [B10H9OC(OH)C6H5]−. In addition, an alternative one-step approach for obtaining the target derivative is postulated. The structure of tetrabutylammonium salts of carboxonium derivative ((C4H9)4N)[2,6-B10H8O2CC6H5] was established with the help of X-ray structure analysis. The reaction pathway for the formation of [2,6-B10H8O2CC6H5]− was investigated with the help of density functional theory (DFT) calculations. This process has an electrophile induced nucleophilic substitution (EINS) mechanism, and intermediate anionic species play a key role. Such intermediates have a structure in which one boron atom coordinates two hydrogen atoms. The regioselectivity for the process of formation for the 2,6-isomer was also proved by theoretical calculations. Generally, in the experimental part, the simple and available approach for producing disubstituted carboxonium derivative was introduced, and the mechanism of this process was investigated with the help of theoretical calculations. The proposed approach can be applicable for the preparation of a wide range of disubstituted derivatives of closo-borate anions

    Эпидемиология и исходы респираторного дистресса у новорожденных

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    Respiratory distress of newborns is one of the most frequent causes of infant admission to intensive care units, the development of severe complications of the neonatal period and lethal outcomes.The objective was to study the epidemiology and outcomes of respiratory distress in newborns requiring intensive care measures.Materials and methods. The design was a retrospective observational study. We examined 180 newborns, the mean weight was 1620 (1075–2197.5) g, and the gestational age was 31.8 (29–34.5) weeks. Apgar score at minute 1 was 5 (4–7) and at minute 5 was 7 (6–7) scores. The duration of artificial lung ventilation was 2 (12.5–242) hours, and the duration of treatment in the NICU was 10 (6–19) days. Lethal outcomes occurred in 6 (3%) cases.Results. The most frequent cause of respiratory distress in newborns was respiratory distress syndrome in newborns (53%). The second place was occupied by asphyxia in childbirth (31%). Intra-amniotic infection was detected in 11 (6%) newborns, and intrauterine pneumonia in 5 (3%) infants. Transient tachypnea was registered in 6 (3%) newborns, and meconium aspiration syndrome – in 8 (4%) patients. In premature infants, the most severe course of respiratory distress was noted in pneumonia and asphyxia, in mature infants – in meconium aspiration syndrome. The maximum duration of intensive care measures was observed in intra-amniotic infection – 16 days and respiratory distress syndrome – 11 days. The outcome in 47% was favorable – complete recovery. Unfavorable outcomes included intraventricular hemorrhage (12%), combination of two or more complications (20%), bronchopulmonary dysplasia (5%), and persistent arterial ductus (4%).Conclusion. The outcome of respiratory distress in newborns with adequate assessment of the severity of the condition and timely initiated evidence-based treatment is determined not by the main clinical diagnosis, but by the gestational age and severity of the infant condition at the time of birth.Респираторный дистресс новорожденных (РДН) является одной из наиболее частых причин поступления детей в отделения интенсивной терапии, развития тяжелых осложнений неонатального периода и летальных исходов.Цель – изучить эпидемиологию и исходы респираторного дистресса у новорожденных, нуждающихся в мероприятиях интенсивной терапии.Материалы и методы. Дизайн – ретроспективное обсервационное исследование. Обследовано 180 новорожденных, средний вес которых составил 1620 (1075–2197,5) г, а гестационный возраст – 31,8 (29–34,5) недель. Оценка по шкале Апгар на 1 мин была 5 (4–7), на 5–7 (6–7) баллов. Продолжительность ИВЛ была равна 2 (12,5–242) ч, а длительность лечения в ОРИТН составила 10 (6–19) суток. Летальные исходы имели место в 6 (3%) случаях.Результаты. Наиболее частой причиной РДН был респираторный дистресс-синдром новорожденных (53%). Второе место занимала асфиксия в родах (31%). Внутриамниотическая инфекция выявлена у 11 (6%) новорожденных, а внутриутробная пневмония – у 5 (3%) детей. Транзиторное тахипноэ зарегистрировано у 6 (3%) новорожденных, а синдром аспирации мекония – у 8 (4%) пациентов. У недоношенных новорожденных наиболее тяжелое течение респираторного дистресса отмечалось при пневмонии и асфиксии, у доношенных детей – при синдроме аспирации мекония. Максимальная продолжительность мероприятий интенсивной терапии была отмечена при внутриамниотической инфекции – 16 суток и респираторном дистресс-синдроме – 11 суток. Исход в 47% случаев был благоприятный – полное выздоровление. Среди неблагоприятных исходов преобладали внутрижелудочковое кровоизлияние (12%), сочетание 2 и более осложнений – (20%), бронхолегочная дисплазия (5%) и персистирование артериального протока (4%).Заключение. Исход респираторного дистресса у новорожденных при адекватной оценке тяжести состояния и своевременно начатом обоснованном лечении определяется не основным клиническим диагнозом, а сроком гестации и тяжестью состояния ребенка на момент рождения
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