Influence of 1% addition of Nb and W on the relaxation process in classical Fe-based amorphous alloys

This paper features investigations into the influence of small additions of alloying elements on: structure, as well as the temporal and thermal stability of magnetic properties, and the disaccommodation effect, for the following amorphous alloys: Fe₆₁Co₁₀Y₈Me₁B₂₀ (where Me = Nb, W). The structure of the investigated samples has been confirmed by the Mössbauer spectroscopy. The obtained results indicate a strong correlation between the structure and the disaccommodation of the studied alloys. The Mössbauer studies reveal different configurations of atoms in the amorphous alloy samples, and the results indicate various potential barriers between orientations of atom pairs. For this reason, to describe the disaccommodation effect, the distribution of activation energy should be taken into account. The distribution of activation energy has been related to the distribution of relaxation times

Thermal stability, crystallization and magnetic properties of Fe-Co-based metallic glasses

The aim of the paper was to investigate thermal stability, crystallization and magnetic properties of Fe-Cobased metallic glasses (MGs). Investigations were carried out on amorphous ribbons with the compositions of [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 and [(Fe0.6Co0.3Ni0.1)0.75 B0.2Si 0.05]96Nb4. Thermal properties (liquidus Tl and melting Tm temperatures) of the pre-alloyed ingots upon heating and cooling were analyzed by DTA at a heating/ cooling rate of 0.33 K s-1 under the purified argon atmosphere. The structure of the ribbons was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) method. Kinetics of the crystallization process was examined by applying differential scanning calorimetry (DSC) method, and experiments performed in thermal analysis involve heating at a constant rates b = 0.17, 0.33 and 0.5 K s-1. Additionally, the conventional crystallization temperature Tx was determined from the normalized isochronal resistivity curves a(T) with heating rate 0.0083 K s-1. a is the temperature coefficient of resistance and a = q-1 dq/dT. The Tx, can be obtained from the condition a = 0 (Stokłosa et al. in J Alloy Compd 509(37):9050–9054, 2011). The saturation magnetization M(T) was measured in situ with heating rates 0.083 K s-1 using magnetic balance (Szewieczek and Lesz in J Mater Process Tech 162–163:254–259, 2005)

Magnetocalorific effect in amorphous and partially-crystallized Fe-Zr-Nb-Cu-B alloy

This paper presents the results of an investigation into the: microstructure, magnetic properties and influence of annealing temperature on the magnetocaloric effect of Fe82Zr7Nb2Cu1B8 alloy in the as-quenched and partially crystalline state. The microstructure was investigated using Mössbauer spectroscopy. The magnetocaloric effect was observed as a change in the magnetic entropy, which was calculated from isothermal magnetization curves. Fully-amorphous Fe82Zr7Nb2Cu1B8 alloys, in the as-quenched state, exhibit a Curie temperature equal to (340 ± 5) K. The transmission Mössbauer spectrum for the as-quenched Fe82Zr7Nb2Cu1B8 alloy is typical for weak ferromagnets with the average hyperfine field of 9.86(2) T. For this alloy in the as-quenched state, the changes in maximum magnetic entropy occur near the Curie points and are equal to 0.95 J/(kg K). Also, the maximum magnetic entropy changes decrease after partial crystallization

Cardiovascular complications after radiotherapy

Over the past decades, effective cancer therapies have resulted in a significant improvement in thesurvival rates for a number of cancers and an increase in the number of cancer survivors. Radiationtherapy is widely used in the treatment of cancer, and it can induce various cardiotoxicities that differconsiderably from chemotherapy-induced cardiotoxicity. They occur primarily as late radiation-inducedcomplications, several years from the end of anticancer treatment and present as coronary artery disease,heart failure, pericardial disease, valvular heart disease and arrhythmias. Patients who recoveredfrom cancer disease suffer from cardiac complications of anticancer treatment, it affects the quality oftheir lives and life expectancy, especially if the diagnosis is delayed. These patients may present distinctsymptoms of cardiac injury, resulting from radiation-induced neurotoxicity and altered pain perception,which makes diagnosis difficult. This review highlights the need for a screening programme for patientswho have undergone radiation therapy and which will subsequently have a potentially profound impacton morbidity and mortality

Magnetic flux jumps in textured Bi2Sr2CaCu2O(8+d)

Magnetic flux jumps in textured Bi2Sr2CaCu2O(8+d) have been studied by means of magnetization measurements in the temperature range between 1.95 K and Tc, in an external magnetic field up to 9 T. Flux jumps were found in the temperature range 1.95 K - 6 K, with the external magnetic field parallel to the c axis of the investigated sample. The effect of sample history on magnetic flux jumping was studied and it was found to be well accounted for by the available theoretical models. The magnetic field sweep rate strongly influences the flux jumping and this effect was interpreted in terms of the influence of both flux creep and the thermal environment of the sample. Strong flux creep was found in the temperature and magnetic field range where flux jumps occur suggesting a relationship between the two. The heat exchange conditions between the sample and the experimental environment also influence the flux jumping behavior. Both these effects stabilize the sample against flux instabilities, and this stabilizing effect increases with decreasing magnetic field sweep rate. Demagnetizing effects are also shown to have a significant influence on flux jumping.Comment: 10 pages, 6 figures, RevTeX4, submitted to Phys. Rev.

Границы устойчивости критического состояния жесткого сверхпроводника Nb₃Al на Н–Т плоскости

Впервые изучена неустойчивость критического состояния сверхпроводника второго рода Nb₃Al при одновременном учете реальных зависимостей тепловых и проводящих свойств материала от температуры Т и магнитного поля Нe. Для этого экспериментально в сильном (до 12 Тл) магнитном поле исследованы зависимости теплоемкости С(Т,Не), намагниченности М(Т,Нe) и магнитострикции ΔL(Т,Нe) сверхпроводника. На основе экспериментальных данных по теплоемкости в широком интервале температур и магнитных полей Hc₁ ≤ He ≤ Hc₂ найдена ширина щели, коэффициент при линейном члене, определяющий электронный вклад в теплоемкость, температура Дебая и другие параметры. Из экспериментальных исследований намагниченности восстановлены зависимости критического тока сверхпроводника Jc(T,He). Используя экспериментальные данные для температурной и полевой зависимостей тепловых и проводящих свойств, рассчитаны петли гистерезиса намагниченности и магнитострикции.Вперше вивчено нестійкість критичного стану надпровідника другого роду Nb₃Al при одночасному обчисленні реальних залежностей теплових та провідних властивостей матеріалу від температури Т та магнітного поля Нe. Для цього експериментально в сильному (до 12 Тл) магнітному полі досліджено залежності теплоємності С(Т,Не), намагніченості М(Т,Нe) та магнітострикції ΔL(Т,Нe) надпровідника. На основі експериментальних даних по теплоємності в широкому інтервалі температур і магнітних полів Hc₁ ≤ He ≤ Hc₂ знайдено ширину щілини, коефіцієнт при лінійному члені, який визначaє електронний вклад в теплоємність, температуру Дебая та інші параметри. З експериментальних досліджень намагніченості побудовано залежності критичного струму надпровідника Jc(T,He). Використовуючи експериментальні дані для температурної і польової залежностей теплових та провідних властивостей, розраховано петлі гістерезису намагніченості та магнітострикції.Stability of the critical state of type-II hard superconductors with respect to small fluctuations of temperature Т or magnetic field Нe is strongly dependent on material properties. For this purpose, heat capacity С(Т,Нe), magnetization М(Т,Нe) and magnetostriction ΔL(Т,Нe) of the superconductor were measured in a strong (up to 12 Т) magnetic field. The experimental data on heat capacity in a wide temperature range and in magnetic fields Hc₁ ≤ He ≤ Hc₂, were used to determine the gap width and some other parameters such as the coefficient of the linear term defining the electron contribution to the heat capacity and the Debye temperature. The experiments on magnetization allowed the critical current dependences of the superconductor Jc(T, He) to be recovered. The experimental data on temperature and field dependences of thermal and conducting properties were used to calculate magnetization and magnetostriction hysteresis loops

Circulating Very Small Embryonic-Like Stem Cells in Cardiovascular Disease

Very small embryonic-like cells (VSELs) are a population of stem cells residing in the bone marrow (BM) and several organs, which undergo mobilization into peripheral blood (PB) following acute myocardial infarction and stroke. These cells express markers of pluripotent stem cells (PSCs), such as Oct-4, Nanog, and SSEA-1, as well as early cardiac, endothelial, and neural tissue developmental markers. VSELs can be effectively isolated from the BM, umbilical cord blood, and PB. Peripheral blood and BM-derived VSELs can be expanded in co-culture with C2C12 myoblast feeder layer and undergo differentiation into cells from all three germ layers, including cardiomyocytes and vascular endothelial cells. Isolation of VSLEs using fluorescence-activated cell sorting multiparameter live cell sorting system is dependent on gating strategy based on their small size and expression of PSC and absence of hematopoietic lineage markers. VSELs express early cardiac and endothelial lineages markers (GATA-4, Nkx2.5/Csx, VE-cadherin, and von Willebrand factor), SDF-1 chemokine receptor CXCR4, and undergo rapid mobilization in acute MI and ischemic stroke. Experiments in mice showed differentiation of BM-derived VSELs into cardiac myocytes and effectiveness of expanded and pre-differentiated VSLEs in improvement of left ventricular ejection fraction after myocardial infarction

Study on crystallization phenomenon and thermal stability of binary Ni–Nb amorphous alloy

In this paper, a ribbon of binary Ni–Nb amorphous alloy was prepared by the melt spinning technique. Glass transition and crystallization phenomenon of the alloy were investigated by differential scanning calorimetry. Thermal properties of the ribbon of binary Ni–Nb upon heating and cooling were analysed by DTA at a heating/ cooling rate of 0.5 K s-1 under the purified argon atmosphere. The thermal stability of Ni–Nb amorphous alloy was studied by using an X-ray diffractometer equipped with an in situ heating system. The structure and fracture morphology of the ribbons were examined by X-ray diffraction and scanning electron microscopy methods