Oxygen Content and Thermodynamic Stability of YBaCo2O6-delta Double Perovskite

The thermodynamic stability of the double perovskite YBaCo2O6−δ was studied using the coulometric titration technique and verified by measurements of the overall conductivity depending on oxygen partial pressure at a given temperature. As a result, the stability diagram of YBaCo2O6−δ was plotted. YBaCo2O6−δ was found to be thermodynamically stable in air at 850°C and higher temperatures, whereas its thermodynamic stability at 900°C is limited by the range of oxygen partial pressures −3.56 ≤ log(pO2/atm) ≤ −0.14. Oxygen content in YBaCo2O6−δ slightly decreases at 900°C from 5.035 at log(pO2/atm) = −0.14 to 4.989 in the atmosphere with log(pO2/atm) = −3.565 indicating a crucial role which variation of Co+3/Co+2 ratio plays in its stability. YBaCo2O6−δ decomposes into the mixture of YCoO3 and BaCoO3−z at the high pO2 stability limit, whereas YBaCo4O7, BaCo1−xYxO3−γ, and Y2O3 were identified as the products of its decomposition at the low pO2 one

Phase Behavior and Defect Structure of HoBaCo₂O_6-δ

The differential scanning calorimetry study showed that the double perovskite HoBaCo2O6-δ (HBC), depending on its oxygen content, undergoes three phase transitions in the temperature range 298–773 K. Their origin was tentatively explained using the relevant literature data. For the single-phase tetragonal HBC, the oxygen nonstoichiometry dependences on the oxygen partial pressure were investigated by thermogravimetric and flow reactor methods in the intermediate-temperature range of 573–773 K. The proposed defect structure of HBC was successfully verified using the obtained data on its oxygen nonstoichiometry combined with those reported earlier. As a result, the values of the thermodynamic parameters (∆Hi∘, ∆Si∘) of the defect reactions proceeding in HBC were determined. The defect structure of HBC was shown to be similar to that of YBaCo2O6-δ (YBC) likely due to similar ionic radii of Ho3+ and Y3+

Thermodynamics of Formation and Disordering of YBaCo₂O_6-δ Double Perovskite as a Base for Novel Dense Ceramic Membrane Materials

Differential scanning calorimetry studies of the complex oxide YBaCo2O6-δ (YBC), combined with the literature data, allowed outlining the phase behavior of YBC depending on the oxygen content and temperature between 298 K and 773 K. The oxygen nonstoichiometry of single-phase tetragonal YBC was measured at different temperatures and oxygen partial pressures by both thermogravimetric and flow reactor methods. The defect structure of YBC was analyzed. As a result, the thermodynamic functions (∆Hi○, ∆Si○) of the defect reactions in YBC were determined. Experimental data on the oxygen content and those calculated based on the theoretical model were shown to be in good agreement. Standard enthalpies of formation at 298.15 K (∆Hf○) were obtained for YBC depending on its oxygen content using solution calorimetry. It was found that ∆Hf○ = f(6-δ) function is linear in the range of (6-δ) from 5.018 to 5.406 and that its slope is close to the value of the enthalpy of the quasichemical reaction describing oxygen exchange between the oxide and ambient atmosphere, which confirms the reliability of the suggested defect structure model

Nonstoichiometry, Defect Chemistry and Oxygen Transport in Fe-Doped Layered Double Perovskite Cobaltite PrBaCo2−xFexO6−δ (x = 0–0.6) Membrane Materials

Mixed conducting cobaltites PrBaCo2−xFexO6−δ (x = 0–0.6) with a double perovskite structure are promising materials for ceramic semi-permeable membranes for oxygen separation and purification due to their fast oxygen exchange and diffusion capability. Here, we report the results of the detailed study of an interplay between the defect chemistry, oxygen nonstoichiometry and oxygen transport in these materials as a function of iron doping. We show that doping leads to a systematic variation of both the thermodynamics of defect formation reactions and oxygen transport properties. Thus, iron doping can be used to optimize the performance of mixed conducting oxygen-permeable double perovskite membrane materials

Age attenuates the T‐type CaV3.2‐RyR axis in vascular smooth muscle

Abstract Caveolae position CaV3.2 (T‐type Ca2+ channel encoded by the α‐3.2 subunit) sufficiently close to RyR (ryanodine receptors) for extracellular Ca2+ influx to trigger Ca2+ sparks and large‐conductance Ca2+‐activated K+ channel feedback in vascular smooth muscle. We hypothesize that this mechanism of Ca2+ spark generation is affected by age. Using smooth muscle cells (VSMCs) from mouse mesenteric arteries, we found that both Cav3.2 channel inhibition by Ni2+ (50 µM) and caveolae disruption by methyl‐ß‐cyclodextrin or genetic abolition of Eps15 homology domain‐containing protein (EHD2) inhibited Ca2+ sparks in cells from young (4 months) but not old (12 months) mice. In accordance, expression of Cav3.2 channel was higher in mesenteric arteries from young than old mice. Similar effects were observed for caveolae density. Using SMAKO Cav1.2−/− mice, caffeine (RyR activator) and thapsigargin (Ca2+ transport ATPase inhibitor), we found that sufficient SR Ca2+ load is a prerequisite for the CaV3.2‐RyR axis to generate Ca2+ sparks. We identified a fraction of Ca2+ sparks in aged VSMCs, which is sensitive to the TRP channel blocker Gd3+ (100 µM), but insensitive to CaV1.2 and CaV3.2 channel blockade. Our data demonstrate that the VSMC CaV3.2‐RyR axis is down‐regulated by aging. This defective CaV3.2‐RyR coupling is counterbalanced by a Gd3+ sensitive Ca2+ pathway providing compensatory Ca2+ influx for triggering Ca2+ sparks in aged VSMCs

Опыт разработки и применения алгоритма клинико-организационного управления при туберкулезе на региональном уровне

Relevance. The high incidence, prevalence and mortality in tuberculosis determines the relevance of improving clinical and organizational processes in terms of algorithmization. The aim of the study was to develop and evaluate the effectiveness of the clinical and organizational management algorithm for tuberculosis medical care at the regional level. Materials and Methods. The object of the study (2007-2021) were the tuberculosis medical care system of the Sverdlovsk region, Russian Federation. The scientific and methodological bases were Department of Health Organization, Drug Supply, Medical Technologies and Hygiene of the Peoples’ Friendship University of Russia topic SRW № 214791-3-000. The development of the algorithm was carried out on the basis of a scientifically proven universal clinical management system. The epidemiological tuberculosis author data and of Rosstat in the Sverdlovsk region for 2007-2020 were used - general and structural morbidity, prevalence, mortality, as well as the number of 3, 4 and 6 groups of dispensary registration of patients. The efficiency of the algorithm was evaluated by the dynamics of the complex of epidemiological indicators of tuberculosis. Research methods were applied: content analysis, analytical, statistical, comparative, expert. Significance was assessed using the t-White test. Differences in the compared parameters were considered significant at p0.05. Results and Discussion. The effectiveness of the developed algorithm for managing regional tuberculosis medical care, including the components of needs analysis, systematization, automation and telecommunications, interdisciplinary integration, resource provision and performance evaluation, was confirmed by a significant decrease in the Sverdlovsk region for the period 2007-2020 general incidence by 2.05 times (from 119.9 to 51.7 per 100 thousand of the population), the incidence of children 0-14 years old by 1.48 times (from 18.7 to 12.6 per 100 thousand children of the corresponding age), prevalence in the population by 1.8 times (from 258.6 to 143 per 100 thousand of the population) and mortality from tuberculosis by 2.675 times (from 21.4 to 8.02 per 100 thousand of the population) (p0.001). The COVID-19 pandemic (2020-2021) did not worsen the epidemiological situation for tuberculosis in the region. In 2020, an active form of tuberculosis was detected in 2201 people, which is 16 % less than in 2019 (p0.05). The prevalence of epidemiologically dangerous bacillary forms of the disease for the period 2019-2020 decreased by 15.4 %, from 73.2 to 61.9 per 100 thousand population (p0.05). Conclusion. Clinical and organizational management of tuberculosis medical care based on the algorithmization of scientifically evidence processes increases the effectiveness of therapeutic and preventive measures and the social and epidemiological well-being of the population.Актуальность. Высокая заболеваемость, распространенность и смертность при туберкулезе определяет актуальность совершенствования клинико-организационных процессов управления методом алгоритмизации. Цель исследования - разработать, внедрить и оценить эффективность алгоритма клинико-организационного управления противотуберкулезной помощью на уровне региона. Материалы и методы. Объектом исследования (2007-2021 гг.) явилась система противотуберкулезной помощи Свердловской области, база и научно-методическое сопровождение осуществлялось кафедрой организации здравоохранения, лекарственного обеспечения, медицинских технологий и гигиены Российского университета дружбы народов в соответствии с темой НИР № 214791-3-000. Разработку алгоритма осуществляли на основании научно доказанной универсальной системы клинического управления. Использована авторская информация и данные по туберкулезу Росстата по Свердловской области 2007-2020 гг. - структура заболеваемости, распространенности, смертность, а также численность пациентов 3, 4 и 6 групп диспансерного учета. Оценку эффективности алгоритма проводили по динамике комплекса эпидемиологических показателей туберкулеза. Применены методы исследования: контент-анализ, аналитический, статистический, сравнительный, экспертный. Для оценки достоверности применялся критерий t-Уайта. Различия сравниваемых показателей считали достоверными при р < 0,05. Результаты и обсуждение. Эффективность разработанного алгоритма управления региональной противотуберкулезной помощью, включающего компоненты анализа потребности, систематизации, автоматизации и телекоммуникации, междисциплинарной интеграции, ресурсного обеспечения и оценки эффективности, подтверждена достоверным снижением в Свердловской области за период 2007-2020 гг. общей заболеваемости в 2,05 раза (с 119,9 до 51,7 на 100 тыс. населения), заболеваемости детей 0-14 лет в 1,48 раза (с 18,7 до 12,6 на 100 тыс. детей соответствующего возраста), распространенности в популяции в 1,8 раза (с 258,6 до 143 на 100 тыс. населения) и смертности от туберкулеза в 2,675 раза (с 21,4 до 8,02 на 100 тыс. населения) (p < 0,001). Пандемия COVID-19 (2020-2021 гг.) не ухудшила эпидемиологическую ситуацию по туберкулезу в регионе. В 2020 г. активная форма туберкулеза выявлена у 2201 человек, что на 16 % меньше, чем в 2019 г. (р < 0,05). Распространенность эпидемиологически опасных бациллярных форм заболевания за период 2019-2020 гг. снизилась на 15,4 %, с 73,2 до 61,9 на 100 тысяч населения (р < 0,05). Заключение. Клинико-организационное управление противотуберкулезной помощью на основе научно-доказанных процессов алгоритмизации повышает результативность лечебно-профилактических мероприятий и социально-эпидемиологическое благополучие населения

Functional Status of Neuronal Calcium Sensor-1 Is Modulated by Zinc Binding

International audienceNeuronal calcium sensor-1 (NCS-1) protein is abundantly expressed in the central nervous system and retinal neurons, where it regulates many vital processes such as synaptic transmission. It coordinates three calcium ions by EF-hands 2-4, thereby transducing Ca 2+ signals to a wide range of protein targets, including G protein-coupled receptors and their kinases. Here, we demonstrate that NCS-1 also has Zn 2+-binding sites, which affect its structural and functional properties upon filling. Fluorescence and circular dichroism experiments reveal the impact of Zn 2+ binding on NCS-1 secondary and tertiary structure. According to atomic absorption spectroscopy and isothermal titration calorimetry studies, apo-NCS-1 has two high-affinity (4 × 10 6 M −1) and one low-affinity (2 × 10 5 M −1) Zn 2+-binding sites, whereas Mg 2+-loaded and Ca 2+-loaded forms (which dominate under physiological conditions) bind two zinc ions with submicromolar affinity. Metal competition analysis and circular dichroism studies suggest that Zn 2+-binding sites of apo-and Mg 2+-loaded NCS-1 overlap with functional EF-hands of the protein. Consistently, high Zn 2+ concentrations displace Mg 2+ from the EF-hands and decrease the stoichiometry of Ca 2+ binding. Meanwhile, one of the EF-hands of Zn 2+-saturated NCS-1 exhibits a 14-fold higher calcium affinity, which increases the overall calcium sensitivity of the protein. Based on QM/MM molecular dynamics simulations, Zn 2+ binding to Ca 2+-loaded NCS-1 could occur at EF-hands 2 and 4. The high-affinity zinc binding increases the thermal stability of Ca 2+-free NCS-1 and favours the interaction of its Ca 2+-loaded form with target proteins, such as dopamine receptor D2R and GRK1. In contrast, low-affinity zinc binding Frontiers in Molecular Neuroscience | www.frontiersin.org