KINETICS OF OXIDATION OF THE ALLOY VT18U

Исследования проведены на экспериментальном сплаве типа ВТ18У с применением методов электронной микроскопии и термогравиметрии. Цель – изучить кинетику окисления сплава при различных температурах в течение 24 часов.Work was carried out on an experimental alloy type VT18U using the methods of electron microscopy and thermogravimetry. The purpose of this work is to study the kinetics of oxidation of the alloy at different temperatures for 24 hours

Why Are Alkali Halide Solid Surfaces Not Wetted By Their Own Melt?

Alkali halide (100) crystal surfaces are anomalous, being very poorly wetted by their own melt at the triple point. We present extensive simulations for NaCl, followed by calculations of the solid-vapor, solid-liquid, and liquid-vapor free energies showing that solid NaCl(100) is a nonmelting surface, and that its full behavior can quantitatively be accounted for within a simple Born-Meyer-Huggins-Fumi-Tosi model potential. The incomplete wetting is traced to the conspiracy of three factors: surface anharmonicities stabilizing the solid surface; a large density jump causing bad liquid-solid adhesion; incipient NaCl molecular correlations destabilizing the liquid surface. The latter is pursued in detail, and it is shown that surface short-range charge order acts to raise the surface tension because incipient NaCl molecular formation anomalously reduces the surface entropy of liquid NaCl much below that of solid NaCl(100).Comment: 4 pages, 3 figure

The influence of modification by superdispersed powders on the lead-tin-base bronze structure

The paper presents data on the influence of additives of the pre-treated aluminium oxide powder on the structure of cast lead-tin-based bronzes. Different quantities of the modifier, based on the superdispersed aluminum oxide powder, were added to the bronze melt. The studies have shown that addition of a small amount of aluminum oxide powder (0.07... 0.25 %) allows modifying the micro structure of the obtained castings. This modification includes grain refinement, reduction of the matrix dendrites size of tin solid solution in copper, as well as formation of spherical inclusions of the low-melting phase - lead. In this case, the addition of such modifier influences weakly the morphology and the quantity of solid eutectoid inclusions based on electron compound Cu[31] Sn[8]

Cr2O3/Al-Al2O3 composite catalysts for hydrocarbons dehydrogenation prepared from aluminum nanopowder

Aluminum nanopowder (10–150 nm) was treated hydrothermally in mild conditions (60–95 °C, at atmospheric pressure), and an aluminum-alumina composite with high porosity and specific surface area was obtained. Cr2O3/Al-Al2O3 catalysts were prepared using the aluminum-alumina composite by impregnation techniques and tested in dehydrogenation of C4-hydrocarbons. It was shown that aluminum-alumina composites had high chemical and phase purity, specific surface area of 150–350 m2/g and the average pore size of 8–13 nm, that is favorable for application as support for catalysts. Cr2O3/Al-Al2O3 catalysts had high activity and selectivity in dehydrogenation of n- and i-butane (conversion of 44–80 mol.% and selectivity >85% at temperatures of 540–610 °C), that is comparable ones for commercial catalysts for CATOFIN, STAR processes

Influence of ultrafine particles on structure, mechanical properties, and strengthening of ductile cast iron

Integrated assessment of the influence of an ultrafine mixture TiO2 + ZrO2 + Na3AlF6 on the formation of the structure, mechanical properties, and strengthening of ductile cast iron was made in the paper. The structural-phase composition of ductile cast iron was studied by means of scanning electron microscopy and a transmission electron microscope. Plastic deformation was determined during testing of uniaxial compression. The change in the structural state of the alloy and in its mechanical properties was observed. Quantitative assessment of contributions of separate physical mechanisms to strengthening characteristics of unmodified and modified ductile cast iron was made

Tuberous sclerosis syndrome: a typical case of a rare disease

The article is devoted to a rare hereditary disease from the group of phak omatoses with an autosomal dominant type of inheritance — Pringle — Burnevill disease. The questions of the prevalence of the disease, the variability of the clinical picture, the timeliness of the clinical diagnosis are considered. Particular attention is paid to skin manifestations and their differential diagnosis. A clinical case of this disease is described

Modern methods of Ta₂O₅ coatings deposition for biomedical applications

The study of e-beam evaporated Ta₂O₅ film structure and properties effect on cell/material response was performed. The surface properties and structure of e-beam evaporated Ta₂O₅ films were investigated by means of XPS and XRD methods. The cytotoxicity and cytocompatibility were estimated by in vitro tests. Films of Ta₂O₅ are bio- and chemically inert, which allows their use in various medical applications, e.g., in diagnostic and treatment techniques employing short-range quasi-static electric fields for stimulation of positive biological processes in live organisms.Дослідження структури та властивостей покриттiв Ta₂O₅, які нанесено методом електронно-променевого випарювання, було зроблено методами рентгеноструктурного аналізу та фотоелектронної спектроскопії. Цитотоксичнiсть i цiтосумiснiсть були визначені in vitro. Плiвки Ta₂O₅ мають бiо- та хімічно- інертні властивості, що сприятиме їх застосуванню з метою діагностики та лікування з використанням близькодіючих квазiстацiонарних електричних полів, якi стимулюють позитивні біологічні процеси.Исследования структуры и свойств покрытий Ta₂O₅, нанесенных методом электронно-лучевого испарения, были проведены методами рентгеноструктурного анализа и фотоэлектронной спектроскопии. Цитотоксичность и цитосовместимость были определены in vitro. Пленки Ta₂O₅ являются био- и химически- инертными, возможно их применение для диагностики и лечения с использованием близкодействующих квазистационарных электрических полей, стимулирующих позитивные биологические процессы