Effect of long-term operation on energy band bending at the SnO2 microcrystals interfaces in thin tin dioxide films with various catalysts

This work presents the results of investigation of stability of energy band bending at the SnO2 microcrystals interfaces in thin films of tin dioxide with deposited Pt and Pd dispersed layers (Pt/Pd/SnO2:Sb) and with the additions of gold in the bulk and on the surface (Au/SnO2:Sb, Au) in long - term operation. Measurements of energy band bending were showed that the significantly variation of this value is observed in first month of the sensor using. Perhaps this phenomenon is caused by the surface reconstruction during operation of sensors and consequently by the increase of density of oxygen ions chemisorbed on the surface of tin dioxide

Properties of resistive hydrogen sensors as a function of additives of 3d-metals introduced in the volume of thin nanocrystalline SnO2 films

Analysis of the results of studying electrical and gas sensitive characteristics of the molecular hydrogen sensors based on thin nanocrystalline SnO2 films coated with dispersed Au layers and containing Au+Ni and Au+Co impurities in the bulk showed that the characteristics of these sensors are more stable under the prolonged exposure to hydrogen in comparison with Au/SnO2:Sb, Au films modified only with gold. It has been found that introduction of the nickel and cobalt additives increases the band bending at the grain boundaries of tin dioxide already in freshly prepared samples, which indicates an increase in the density Ni of the chemisorbed oxygen. It is important that during testing, the band bending eφs at the grain boundaries of tin dioxide additionally slightly increases. It can be assumed that during crystallization of films under thermal annealing, the 3d-metal atoms in the SnO2 volume partially segregate on the surface of microcrystals and form bonds with lattice oxygen, the superstoichiometric tin atoms are formed, and the density Ni increases. If the bonds of oxygen with nickel and cobalt are stronger than those with tin, then, under the prolonged tests, atomic hydrogen will be oxidized not by lattice oxygen, but mainly by the chemisorbed one. In this case, stability of the sensors’ characteristics increases

Hydrogen sensors based on In2O3 thin films with bimetallic Pt/Pd catalysts on the surface and tin and dysprosium impuri-ties in the bulk

This paper presents the results of studying the characteristics of hydrogen sensors based on thin In2O3 films modified with tin and dysprosium with dispersed double Pt/Pd catalysts deposited on the surface. To control the content of Sn and Dy in the films, an original technology was developed, and ceramic targets were fabricated from powders of the In–Dy–O, Dy–Sn–O, and In–Dy–Sn–O systems synthesized by the sol–gel method. Films of complex composition were obtained by RF magnetron sputtering of the corresponding targets. Structural features of the obtained thin films were studied by Raman spectroscopy. It is shown that various combinations of tin and dysprosium concentrations, as well as the presence of Pt/Pd catalysts on the surface, have a significant effect on the defectiveness of the films and the density of oxygen adsorption centers. As a result, the resistance of sensors in pure air (R0), the activation energies of the temperature dependences of R0, the bending of the energy bands at the grain boundaries of the semiconductor, and the responses to the action of hydrogen in the concentration range of 20–25,000 ppm change. A unique feature of Pt/Pd/ In2O3: Sn (0.5 at%), Dy (4.95 at%) films is their high sensitivity at 20–100 ppm and the absence of signal saturation in the region of high hydrogen concentrations of 5000–25,000 ppm, allowing them to be used to detect H2 in a wide range of concentrations

УЛЬТРАСТРУКТУРА СИНАПСОВ В ГИППОКАМПЕ КРЫС В ПРОЦЕССЕ СТАРЕНИЯ

The aim of the study was to examine age-related changes in the ultrastructure of synapses in the CA1 region of the hippocampus of Wistar rats and premature aging OXYS rats.To assess changes of the sinaptoarhitectonics photographed on 15 randomly chosen fields of view of the pyramidal layer of the CA1 region of the hippocampus with five slices at a standard magnification of 10000. It was determined the amount of mineral contacts (size of the field of view is 50 μm2) and calculated numerical density of synapses per 100 μm2. The number of contacts with asymmetric and symmetric organization sistemasubsidiaries units, perforated, hypertrophic contacts are counted.The study showed that there are significant differences in the ultrastructural organization of the synapses between the lines, already 4 months old. The numerical density of snaps in this age group OXYS rats was significantly higher than that of Wistar. Ultrastructure of synapses in the CA1 region of the hippocampus of rats at the age of 18 months more bulupodadan pathological essentiaompetencies processes and membrane prematurely senescent rats in contrast to the control line. The numerical indicator of protect contents 18-month-old rats OXYS was significantly lower than in Wistar.Identified interstrain differences in the degree of changes of synapses can testify in favor of a different sensitivity to oxidative stress in rats investigated lines.Цель исследования – изучить возрастные изменения ультраструктуры синапсов СА1-региона гиппокампа крыс линии Wistar и преждевременно стареющих крыс линии OXYS.Материал и методы. Для оценки изменений синаптоархитектоники фотографировали по 15 случайно выбранных полей зрения пирамидного слоя СА1-региона гиппокампа с пяти срезов при стандартном увеличении 10 000. Определяли количество межнейрональных контактов (площадь поля зрения – 50 мкм2) и высчитывали численную плотность синапсов на 100 мкм2. Подсчитывали количество определенных контактов с асимметричной и симметричной организацией системы субсинаптических единиц, перфорированные, гипертрофированные контакты. Подразделяли синапсы по протяженности активной зоны контакта.Результаты. Проведенное исследование показало, что существенные различия в ультраструктурной организации синапсов между линиями наблюдаются уже в 4-месячном возрасте. Численная плотность синапсов в этой возрастной группе у крыс OXYS была значимо выше, чем у Wistar. Ультраструктура синапсов СА1-региона гиппокампа крыс в возрасте 18 мес в большей степени была подвержена патологическим изменениям пресинаптических отростков и мембраны у преждевременно стареющих крыс в отличии от линии контроля. Показатель численной плотности контактов  18-месячных крыс OXYS был значимо ниже, чем у линии Wistar. Выявленные межлинейные различия по степени изменений синапсов могут свидетельствовать в пользу разной чувствительности к окислительному стрессу крыс исследуемых линий

REPARATIVE PROPERTIES OF LINSEED OIL AT ALCOHOLIC GASTRITIS

This article evaluated the reparative properties of linseed oil in acute alcoholic gastritis

Участие растворимых антигенов адгезии и молекул гистосовместимости в развитии бронхиальной астмы у детей

We determined serum levels of soluble adhesion antigens CD50, CD54, soluble HLA class I molecules, HLA-DR, and relative number of antigenpositive blood mononuclears in asthmatic children. Increased concentrations of soluble CD54 and CD54 antigens and reduction in relative number of CD50+ and CD54+ mononuclear cells were revealed. In children with asthma, the level of serum soluble HLA-DR antigens and relative number of peripheral blood mononuclears were elevated. The worsening of asthma course was accompanied by the increase in CD50, CD54, HLA-DR serum levels. The inverse correlation between the serum levels of soluble CD54 and HLA-DR antigens and FEF50 was revealed.У детей с бронхиальной астмой (БА) определяли сывороточный уровень растворимых антигенов адгезии CD50, CD54, растворимых молекул HLA I класса и HLA-DR и относительное количество мононуклеарных клеток периферической крови, положительных по этим же антигенам. Отмечено увеличение сывороточного содержания растворимых CD50и CD54-антигенов на фоне снижения относительного содержания CD50+ и CD54+ мононуклеарных клеток. У детей с БА обнаружено повышение сывороточного уровня растворимых антигенов HLA-DR и HLA-DR+ мононуклеарных клеток периферической крови. Утяжеление БА сопровождалось увеличением сывороточного уровня растворимых CD50-, CD54-антигенов и молекул HLA-DR. Выявлена отрицательная корреляционная связь между сывороточной концентрацией растворимых антигенов CD54 и HLA-DR и величиной коэффициента МОС50, отражающего проходимость средних бронхов, а также относительным содержанием HLA-DR+ мононуклеарных клеток крови и величиной коэффициента МОС75, отражающего степень проходимости крупных бронхов