Influence of the thermal factor on the composition of electron-beam high-entropy ALTiVCrNbMo coatings

This paper reports results of studying the element and phase compositions of electron-beam coatings based on the high-entropy alloy AlTiVCrNbMo, depending on the deposition temperature (in the range of 300...700 °С). The high-entropy alloys were melted in an arc furnace in an atmosphere of high-purity argon. Vacuum condensates of the high-entropy alloy (AlTiVCrNbMo) with a thickness of 3–5 µm were obtained in the vacuum setup UVN-2M-1 at a working vacuum of 5·10-5 mТоrr. The alloy evaporation was performed from the water-cooled ingot mold using an electron-beam gun with a power of 5 kW. Condensation of vapors of all the elements of the alloy was performed onto copper substrates at temperatures of 300, 500, 700 °C. Based on analysis of the element composition of materials of the target made of the high-entropy six-element alloy AlTiVCrNbMo and electron-beam coatings, based on it, we established the critical parameter (specific heat of vaporization of an element) that defined a selective change in the element composition. In accordance with a characteristic change in the composition of coatings of the multi-element high-entropy alloy, 3 groups of elements were distinguished: with a specific heat of evaporation of 280...350 kJ/mol (group 1), 420…460 kJ/mol (group 2), and 590…680 kJ/mol (group 3). It was shown that the formation of a single-phase coating of the high-entropy alloy (based on BCC of the crystalline lattice) occurs at the higher deposition temperature of 500...700 °C when the coating consists of not less than 5 elements. It was established that based on the conditions for an electron-beam process of materials formation, the results obtained can be divided into two types: those determined by the condition of evaporation of the target and those determined by the conditions of coating deposition. The density of flows of elements, evaporated from the target, is determined by their specific heat of evaporation. However, the ratio of atoms in the flow, derived in this way, may not be retained in the formed coating due to the secondary evaporation of elements from the growth surface. The obtained results allow us to substantiate principles for the selection of components for achieving the optimal element and phase compositions of high-entropy alloys.На основі аналізу елементного складу матеріалів мішені з високоентропійного шестиелементного сплаву AlTiVCrNbMo і електронно-променевих покриттів на його основі встановлено критичний параметр (питома теплота випаровування елемента), який визначає селективну зміну елементного складу. Показано, що формування однофазного покриття високоентропійного сплаву відбувається, коли до складу покриття входить не менше 5 елементів. Отримані результати дозволяють обґрунтувати принципи підбору компонент для досягнення оптимальних елементного та фазового складу високоентропійних сплавів

A rare combination of noncompact myocardium and coronary dilatation with type 1 neurofibromatosis

The article describes the observation of a child with a very rare combination of noncompact left ventricular myocardium and coronary dilatation in type 1 neurofibromatosis (NF1). The first of these complications, undifferentiated cardiomyopathy, also known as noncompact myocardium, is not described in combination with nF 1 in available literature, although cases of hypertrophic cardiomyopathy in patients with NF 1 have been previously reported. Dilatation of the coronary arteries also refers to infrequent manifestations of vascular pathology against the background of neurofibromatosis, and the combination of all three signs (NF 1, noncompact myocardium and coronary dilatation) has not yet been reported by other authors. When examining the patient, we found the characteristic signs of NF 1 (foci of "coffee" pigmentation on the skin, multiple nevuses, fibroids of the forearm, cognitive disorders), electrocardiogram features of left ventricular hypertrophy, negative T-tooth and ST-segment displacement 1 mm below the isoline in Leads V4-6, in echocardiography - pronounced trabecularity, thinning of the compact myocardium layer and a "spongy myocardium" in the region of the left ventricle apex, dilatation of the coronary arteries. With magnetic resonance imaging, signs of noncompact myocardium of the left ventricle were found, with selective coronary angiography - slowing of the coronary blood flow. The patient receives the permanent treatment for heart failure and aspirin, his condition remains stable for 4 years of follow-u

Ultrasound diagnostics of left ventricular noncompaction

The clinical cases of rare, genetically heterogeneous cardiomyopathy are described - the left ventricular noncompaction (LVNC) cardiomyopathy for four children (three boys and one girl) in age from two months to 6 years. Description of echocardiography signs is presented in accordance with modern diagnostic criteria. Noncompaction of the left ventricle is recognized in three patients, of the left and right ventricle - in one. In three patients out of four, LVNC was a separate disease, and yet in one it was associated with neurofibromatosis type 1, in combination with dilatation of coronary arteries and pericardial effusion. Three of four patients were admitted with congestive heart failure (CHF) of New York Heart Association (NYHA) functional class 3-4 (FC), and one - with CHF 2 FC. The echocardiograms are brought with description of characteristic features of LVNC (hypertrabecularity, spongy myocardium on the apex of the left ventricle, typical correlation of incompact and compact layer from 2.0 to 2.6). All four patients received treatment for CHF (diuretics, beta-blockers, captopril, in one case - digoxin); two out of four got antithrombotic therapy (aspirin, warfarin). Results of follow-up observation of the patients are described with the estimation of echocardiography signs, including dilatation of coronary arteries. Left ventricular ejection fraction - both by Simpson and Teicholz - increased in two patients, with therapy of chronic heart failure at a follow-up visits over > 5 years simultaneously with the decline of severity of CHF. Another two patients have been examined from 2 months to 5 years and have had CHF 3 FC; their left ventricular ejection fraction increased too, but cardiomegaly and right ventricular heart failure preserved

Influence of the thermal factor on the composition of electron-beam high-entropy ALTiVCrNbMo coatings

This paper reports results of studying the element and phase compositions of electron-beam coatings based on the high-entropy alloy AlTiVCrNbMo, depending on the deposition temperature (in the range of 300...700 °С). The high-entropy alloys were melted in an arc furnace in an atmosphere of high-purity argon. Vacuum condensates of the high-entropy alloy (AlTiVCrNbMo) with a thickness of 3–5 µm were obtained in the vacuum setup UVN-2M-1 at a working vacuum of 5·10-5 mТоrr. The alloy evaporation was performed from the water-cooled ingot mold using an electron-beam gun with a power of 5 kW. Condensation of vapors of all the elements of the alloy was performed onto copper substrates at temperatures of 300, 500, 700 °C. Based on analysis of the element composition of materials of the target made of the high-entropy six-element alloy AlTiVCrNbMo and electron-beam coatings, based on it, we established the critical parameter (specific heat of vaporization of an element) that defined a selective change in the element composition. In accordance with a characteristic change in the composition of coatings of the multi-element high-entropy alloy, 3 groups of elements were distinguished: with a specific heat of evaporation of 280...350 kJ/mol (group 1), 420…460 kJ/mol (group 2), and 590…680 kJ/mol (group 3). It was shown that the formation of a single-phase coating of the high-entropy alloy (based on BCC of the crystalline lattice) occurs at the higher deposition temperature of 500...700 °C when the coating consists of not less than 5 elements. It was established that based on the conditions for an electron-beam process of materials formation, the results obtained can be divided into two types: those determined by the condition of evaporation of the target and those determined by the conditions of coating deposition. The density of flows of elements, evaporated from the target, is determined by their specific heat of evaporation. However, the ratio of atoms in the flow, derived in this way, may not be retained in the formed coating due to the secondary evaporation of elements from the growth surface. The obtained results allow us to substantiate principles for the selection of components for achieving the optimal element and phase compositions of high-entropy alloys.На основі аналізу елементного складу матеріалів мішені з високоентропійного шестиелементного сплаву AlTiVCrNbMo і електронно-променевих покриттів на його основі встановлено критичний параметр (питома теплота випаровування елемента), який визначає селективну зміну елементного складу. Показано, що формування однофазного покриття високоентропійного сплаву відбувається, коли до складу покриття входить не менше 5 елементів. Отримані результати дозволяють обґрунтувати принципи підбору компонент для досягнення оптимальних елементного та фазового складу високоентропійних сплавів

Mathematical Modeling of the Corrosion Behavior of Austenitic Steels in Chloride-Containing Media During the Operation of Plate-Like Heat Exchangers

 Mathematical models that describe the dependences of the critical temperatures of pitting formation of AISI 304, 08Kh18N10, AISI 321, 12Kh18N10T steels in model circulating waters with pH 4…8 and chloride concentrations from 350 to 600 mg/l on their chemical composition and structure have been developed. They are based on linear squares regressions and a feed-forward neural network for reduced feature numbers. Using the developed mathematical models, it was found that the critical pitting temperatures of these steels increase with an increase in the pH of the circulating water, the number of oxides up to 3.95 μm in size, the average distance between titanium nitrides, the Cr content and a decrease in the concentration of chlorides in the circulating waters, the average distance between oxides and average austenite grain diameter. At the same time, it was found that the geometric dimensions of the steel structure most intensively affect their pitting resistance in circulating waters, and the effect of their chemical composition is minimal and is determined by the amount of Cr, which contributes to an increase in the pitting resistance of steels, probably increasing the solubility of nitrogen in the austenite solid solution. It is proposed to use the developed mathematical models to select the optimal heats of these steels for the production of heat exchangers and predict their pitting resistance during their operation in circulating waters

Quantum equivalence of sigma models related by non Abelian Duality Transformations

Coupling constant renormalization is investigated in 2 dimensional sigma models related by non Abelian duality transformations. In this respect it is shown that in the one loop order of perturbation theory the duals of a one parameter family of models, interpolating between the SU(2) principal model and the O(3) sigma model, exhibit the same behaviour as the original models. For the O(3) model also the two loop equivalence is investigated, and is found to be broken just like in the already known example of the principal model.Comment: As a result of the collaboration of new authors the previously overlooked gauge contribution is inserted into eq.(43) changing not so much the formulae as part of the conclusion: for the models considered non Abelian duality is OK in one loo

Порівняльна оцінка результатів хірургічного та консервативного лікування хворих з цукровим діабетом та хронічною критичною ішемією нижньої кінцівки

Мета. Порівняти результати консервативного лікування та ендоваскулярних і відкритих хірургічних втручань у хворих з цукровим діабетом та хронічною критичною ішемією нижньої кінцівки. Матеріали і методи. Проаналізовано результати лікування 240 пацієнтів з цукровим діабетом (ЦД) 2-го типу та хронічною критичною ішемією нижньої кінцівки (ХКІНК), виразково-некротичним ураженням стопи на тлі стенотично - оклюзійного ураження артерій підколінно-гомілково-стопового сегмента. До групи А включили 143 (54,6%) пацієнти, яким було проведено хірургічне лікування, до групи Б – 97 (40,4%) пацієнтів, яких лікували консервативно. У свою чергу групу А розподілили на дві підгрупи: А1 – 42 (29,4%) пацієнти, яким виконали операцію шунтування до гомілкових або стопових артерій, та А2 - 101 (70,6%) пацієнт, якому виконали балонну ангіопластику. З метою коректного порівняння результатів різних видів лікування нами була розроблена методика розрахунку коефіцієнта рівня ампутації (КРА). Результати. Із 42 хворих підгрупи А1 у 4 (9,5%) була виконана ампутація на рівні стегна, у 3 (7,1%) - на рівні гомілки, у 6 (14,3%) – трансметатарзальна резекція стопи, у 14 (33,3%) – ампутація пальців. У 15 (35,7%) хворих опорна функція стопи не порушилась. КРА у пацієнтів підгрупи А1 дорівнював 1,48. Із 101 хворого підгрупи А2 у 2 (2,0%) була виконана ампутація на рівні стегна, у 4 (4,0%) - на рівні гомілки, у 16 (15,8%) – трансметатарзальна резекція стопи, у 19 (18,8%) – ампутація пальців. У 60 (59,4%) хворих опорна функція стопи не порушилась. КРА у пацієнтів підгрупи А2 дорівнював 0,78. Із 97 хворих групи Б у 22 (22,7%) була виконана ампутація на рівні стегна, у 29 (29,9%) - на рівні гомілки, у 6 (6,2%) – трансметатарзальна резекція стопи, у 11 (11,3%) – ампутація пальців. У 29 (29,9%) хворих опорна функція стопи не порушилась. КРА у пацієнтів групи Б дорівнював 2,79. Висновки. Розроблена методика розрахунку КРА може бути використана для порівняння результатів лікування хворих з ЦД та ХКІНК на тлі стенотично-оклюзійного ураження артерій підколінно-гомілково-стопового сегмента, у яких були застосовані різні методи лікування. Найкращі річні результати збереження опорної функції нижньої кінцівки спостерігали у хворих, яким виконали балонну ангіопластику, найгірші - у хворих, яким було проведено консервативне лікування

СЛУЧАЙ ВЫСОКОГО УРОВНЯ НАКОПЛЕНИЯ 18F-ФДГ В ЛЕЙОМИОМЕ ПИЩЕВОДА И ЖЕЛУДКА

Benign tumors of the esophagus and stomach are rare lesions and they usually present as leiomyomas. There have been no published reports indicating high metabolic activity of leiomyomas, detected by PET-CT. In the present case, gastric leiomyoma extending into the esophagus was found to have a high 18F-FDG uptake.Доброкачественные опухоли пищевода и желудка являются относительно редкими заболеваниями, обычно они представлены лейомиомами. В литературе нет указаний на возможность высокой метаболической активности лейомиом. В представленном клиническом случае лейомиома желудка с переходом на пищевод, в последующем подтвержденная гистологическим и иммуногистохимическим исследованиями, обладала высоким уровнем накопления 18F-ФДГ