Surface Tension and Density of Fe–Mn Melts

Abstract: The article presents original experimental data on surface tension of the Fe100 – xMnx (x = 4–13 wt %) melts. Surface tension and density of the melt were measured by the sessile drop method at heating from the liquidus temperature to 1780°C and subsequent sample cooling in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe–Mn melts were plotted. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe–Mn melts decreases as Mn content increases. Experimental data on the surface tension of Fe–Mn melts is consistent with the theoretical dependences (the Pavlov–Popel’ equation and the Shishkovsky equation). During the investigation of Fe–Mn melt microheterogenity, correlation between the values of kinematic viscosity, surface tension, and density is revealed. Fluidity dependence of Fe–Mn melts on their density in the cooling mode has a linear character which indicates satisfaction of the Bachinskii law. Discrepancy in the melt viscosity ratios to the surface tension coefficient obtained from the experimental data and from the empirical formula is discovered. Using the experimental data on viscosity and surface tension of Fe–Mn melts, the entropy change in the melt’s bulk and the change in the melt’s surface entropy, respectively, are studied. The surface entropy and the bulk entropy in the melt decrease in their absolute value with its increasing Mn content. From the study results, it is concluded that there is no destruction of the microheterogeneous structure of Fe100 – xMnx (x = 4–13 wt %) melts when heated up to 1780°C. © 2020, Allerton Press, Inc.The reported study was funded by Russian Foundation for Basic Research, project no. 19-33-90198

Study of structure-property relationship in steels based on analysis of EBSD data

In this work, we formulate novel data-driven assays for exploring the structure-property linkages for high-manganese austenitic wear-resistant steel 110G13L (Hadfield steel). Steel 110G13L has the following chemical composition, wt.%: C(0.95-1.50)-Mn(11.5-15.0). These assays are built on recent advances in high resolution quantification of material structure using correlations and principal analyses of electron backscatter diffraction (EBSD) data, as well as in the mechanical characterization using nanoindentation. These novel protocols are demonstrated on a steel 110G13L that exhibits various polycrystalline microstructures. A comparative analysis of EBSD data was carried out for samples of manganese steel 110G13L obtained by various methods. Analysis of the diffraction patterns of backscattered electrons allowed us to plot orientation maps, Schmid factor maps and distributions for austenite dendrites. Schmid factor maps are used to determine the degree of homogeneity of a possible deformation. The results of the measurement of hardness and Young's modulus for the austenite dendrites indicate the heterogeneity of the mechanical properties of the material in submicro-volumes due to lattice defects (dislocations) inside the crystallites. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 19-33-90198The equipment of the Ural Centre for Shared Use “Modern nanotechnology” UrFU was used. The reported study was funded by RFBR (project No. 19-33-90198)

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

International audiencePreseismic intensification of fracturing has been investigated from occurrence analysis of seismo-acoustic pulses (SA foreshocks) and ULF magnetic pulses (ULF foreshocks) observed in Karimshino station in addition to seismic foreshocks. Such analysis is produced for about 40 rather strong and nearby isolated earthquakes during 2 years of recording. It is found that occurrence rate of SA foreshocks increases in the interval (-12, 0 h) before main shock with 3-times exceeding of background level in the interval (-6, -3 h), and occurrence probability of SA foreshocks (pA~75%) is higher than probability of seismic foreshocks (ps~30%) in the same time interval.ULF foreshocks are masked by regular ULF activity at local morning and daytime, nevertheless we have discovered an essential ULF intensity increase in the interval (-3, +1 h) at the frequency range 0.05-0.3 Hz. Estimated occurrence probability of ULF foreshocks is about 40%. After theoretical consideration we conclude: 1) Taking into account the number rate of SA foreshocks, their amplitude and frequency range, they emit due to opening of fractures with size of L=70-200 m (M=1-2); 2) The electro-kinetic effect is the most promising mechanism of ULF foreshocks, but it is efficient only if two special conditions are fulfilled: a) origin of fractures near fluid-saturated places or liquid reservoirs (aquifers); b) appearance of open porosity or initiation of percolation instability; 3) Both SA and ULF magnetic field pulses are related to near-distant fractures (r<20-30 km); 4) Taking into account number rate and activation period of seismic, SA and ULF foreshocks, it is rather probable that opening of fractures and rupture of fluid reservoirs occur in the large preparation area with horizontal size about 100-200km

Excitation of durable VHF oscillations in ferrite-filled coaxial lines

Effective methods are suggested for exciting gigahertz-range oscillations in coaxial lines that contain ferrite rings and isotropic material. Within the gyrotropic section, the primary pulsed waveform gets transformed from the TEM into a TM mode. Its further development is analyzed, following the results of real-life and numerical experiments. Special attention is paid to amplitude variations of the ТМ mode, owing to the nonlinear response of the ferrite.Пропонуються ефективні методи збудження осциляцій гігагерцевого діапазону в коаксіальних лініях, що містять уставки з феритових кілець та ізотропного матеріалу. У гіротропній частині лінії первинна імпульсна хвильова форма трансформується з моди ТЕМ у моду ТМ. Проаналізовано їх подальший розвиток за результатами відповідних натурних і числових експериментів. Особливої уваги приділено варіаціям амплітуди ТМ-моди, що пов’язані з нелінійністю електромагнітного відгуку фериту

About possibility to locate an EQ epicenter using parameters of ELF/ULF preseismic emission

A relation between parameters of preseismic ULF/ELF emissions and EQ is studied. The magnetic data measured at Karymshino station (Kamchatka, Russia) along with data on local seismic activity during eight years of observations (2001–2008) are taken for the analysis. Source azimuth is detected in different techniques, based on the analysis of the total field and its polarized pulsed component. The latter technique shows a better accuracy in the source azimuth detection. The errors of the method are associated with existence of non-seismic sources and with use of one-point observation. The second error can be eliminated by development of multi-point observations

НЕИНВАЗИВНАЯ ОЦЕНКА ФРАКЦИОННОГО РЕЗЕРВА КРОВОТОКА У ПАЦИЕНТОВ С ИШЕМИЧЕСКОЙ БОЛЕЗНЬЮ СЕРДЦА ПО ДАННЫМ КОМПЬЮТЕРНОЙ ТОМОГРАФИИ: ПЕРВЫЕ РЕЗУЛЬТАТЫ КЛИНИЧЕСКОГО ПРИМЕНЕНИЯ. СРАВНЕНИЕ С ДАННЫМИ ИНВАЗИВНОГО ИЗМЕРЕНИЯ

Objectives: to determine the diagnostic performance of non-invasive FFR derived from standard acquired coronary computed tomography angiography (CTA) datasets (FFRCT) for the diagnosis of myocardial ischemia in patients with suspected stable coronary artery disease (CAD).Methods. Prospective study included 16 patients ((m/f – 13/3 mean age 47.8 ± 2.3 years) with CAD and coronary stenosis 40–75% lumen reduction. Coronary CTA was performed prior to ICA with invasive FFR measurement. FFRCT was calculated and interpreted in a blinded fashion by an independent Core Laboratory (HeartFlow, USA). Results were compared to invasively measured FFR, with ischemia defined as FFRCT or FFR ≤ 0.80.Results. The area under the receiver operating characteristic curve (95% CI) for FFCT was 0.90. Per-vessel sensitivity and specificity to identify myocardial ischemia were 91% and 89% for FFRCT.Conclusion. FFRCT provides high diagnostic accuracy, and discrimination for the diagnosis of hemodynamically significant CAD with invasive FFR as the reference standard. Цель исследования: оценить диагностическую значимость неинвазивного измерения фракционного резерва кровотока (FFR) по данным МСКТ-коронарографии (FFRCT) в определении значимых стенозов коронарных артерий у пациентов с ишемической болезнью сердца (ИБС).Материал и методы. В проспективное исследование было включено 16 пациентов (м/ж – 13/3, средний возраст 47,8 ± 2,3 года) с ИБС и стенозами коронарных артерий 40–75% просвета артерии. Вначале пациентам выполняли КТ-ангиографию, затем – инвазивную коронарографию с измерением FFR. Измерение FFRCT проводили слепым методом независимой лабораторией Core Laboratory (HeartFlow, США). Результаты FFRCT были сопоставлены с инвазивным измерением FFR. Пороговое значение значимости стеноза определялось как FFR и FFRCT ≤ 0,80.Результаты. Площадь под ROC-кривой (AUC) (95% CI) для FFRCT составила 0,9. Чувствительность и специфичность в определении гемодинамически значимых стенозов для FFRCT составили 91 и 79% соответственно.Выводы. FFRCT представляет собой инновационный метод, демонстрирующий высокую диагностическую значимость для выявления или исключения поражения коронарных артерий, вызывающих ишемию

Сосудистые кальцинаты молочной железы как проявление системного атеросклероза

Cardiovascular diseases (CVD) are socially significant diseases and one of the main causes of death among women. There are no effective and uniform screening methods to prevent the prevalence and mortality of CVD. Breast artery calcifications may be one of the available tools for CVD risk stratification. The pathogenesis of calcification of the middle vessel wall, known as Mönckeberg's arteriosclerosis, is different from the pathogenesis of coronary atherosclerosis that coronary arteries. However, research data supports a correlation between breast artery calcifications and risk factors for CVD. These factors include coronary atherosclerosis, detected by CT-coronarography.Purpose. To assess the prevalence of breast arterial calcification and to determine the association with cardiovascular risk factors, coronary artery calcification, atherosclerosis of brachiocephalic arteries and visceral branches of the abdominal aorta.Material and methods. 21 patients were hospitalized in the cardiology department. The patients underwent digital mammography to detect breast arterial calcifications. All patients also underwent CT coronary angiography with angiography of the abdominal aorta.Results. The use of the Wilcoxon-Mann-Whitney W-test with an abnormal distribution showed a correlation between the breast arterial calcifications and the calcium index (p = 0.0028), coronary artery stenosis (p = 0.040), calcification of the thoracic aorta wall (p = 0.035) and stenosis of the visceral branches of the abdominal aorta (p = 0.037).Conclusions. The breast arterial calcifications correlates with a more frequent detection of calcifications in the walls of the coronary arteries and a higher calcium index.Сердечно-сосудистые заболевания (ССЗ) относятся к социально значимым заболеваниям и являются одной из основных причин смертности среди женщин. Отсутствие эффективных и унифицированных методов скрининга препятствует уменьшению заболеваемости и распространенности ССЗ и смертности от них. Сосудистые кальцинаты в молочной железе могут стать одним из доступных инструментов страти фикации риска ССЗ. Патогенез кальциноза средней оболочки артерий, известный как артериокальциноз Менкеберга, отличается от патогенеза атеросклероза интимы, возникающего в коронарных артериях. Тем не менее исследования подтверждают корреляцию между сосудистыми кальцинатами в молочной железе и факторами риска ССЗ. К таким факторам относится атеросклероз коронарных артерий, выявляемый с помощью КТ-коронарографии.Цель работы: изучение связи сосудистых кальцинатов в молочной железе с факторами риска сердечно-сосудистых заболеваний, атеросклерозом коронарных артерий, брахиоцефальных артерий и висцеральных ветвей брюшной аорты.Материал и методы. 21 пациентка, находящаяся на стационарном лечении в отделении кардиологии, была обследована на наличие сосудистых кальцинатов в молочных железах с помощью цифровой маммографии. Также всем пациенткам была выполнена КТ-коронарография с ангиографией брюшной аорты.Результаты. Применение W-критерия Уилкоксона–Манна–Уитни при ненормальном распределении показало взаимосвязь между наличием сосудистых кальцинатов в молочной железе и кальциевым индексом (р = 0,0028), стенозами коронарных артерий (р = 0,040), кальцинозом стенки грудной аорты (р = 0,035) и стенозами висцеральных ветвей брюшной аорты (р = 0,037).Заключение. Наличие кальцинатов в стенках сосудов молочных желез коррелирует с более частым выявлением кальцинатов в стенках коронарных артерий и более высоким кальциевым индексом