Superconductivity in a new hexagonal high entropy alloy

High entropy alloys (HEAs) are the new class of materials with an attractive combination of tunable mechanical and physicochemical properties. They crystallize mainly in cubic structures, however, for practical applications, HEAs with hexagonal close-packed (hcp) structure are highly desirable in connection to their in general high hardness. Herein, we report the synthesis, structure and detailed superconducting properties of Re$_{0.56}$Nb$_{0.11}$Ti$_{0.11}$Zr$_{0.11}$Hf$_{0.11}$-the first hexagonal superconducting high entropy alloy (HEA) composed of five randomly distributed transition-metals. Combination of room temperature precession electron diffraction, precession electron diffraction tomography and powder X-ray diffraction is utilized to determine the room temperature crystal structure. Transport, magnetic and heat capacity measurements show that the material is a type-II superconductor with the bulk superconducting transition at $T_{c}$ = 4.4 K, lower critical field $H_{c1}$(0) = 2.3 mT and upper critical field $H_{c2}$(0) = 3.6 T. Low-temperature specific heat measurement indicates that Re$_{0.56}$Nb$_{0.11}$Ti$_{0.11}$Zr$_{0.11}$Hf$_{0.11}$ is a phonon-mediated superconductor in the weak electron-phonon coupling limit with a normalized specific heat jump $\frac{\Delta C_{el}}{\gamma_{n}T_{c}}$ = 1.32. Further, hexagonal to cubic structural transition is observed by lowering the valence electron counts and $T_{c}$ follows crystalline-like behaviour.Comment: 6 Pages, 9 Figures. arXiv admin note: text overlap with arXiv:1804.1009

Surviving sepsis: going beyond the guidelines

The Surviving Sepsis Campaign is a global effort to improve the care of patients with severe sepsis and septic shock. The first Surviving Sepsis Campaign Guidelines were published in 2004 with an updated version published in 2008. These guidelines have been endorsed by many professional organizations throughout the world and come regarded as the standard of care for the management of patients with severe sepsis. Unfortunately, most of the recommendations of these guidelines are not evidence-based. Furthermore, the major components of the 6-hour bundle are based on a single-center study whose validity has been recently under increasing scrutiny. This paper reviews the validity of the Surviving Sepsis Campaign 6-hour bundle and provides a more evidence-based approach to the initial resuscitation of patients with severe sepsis

Determinants for milk fever An epidemiological study of Swedish dairy cows

Milk fever is a worldwide disease, seen mainly in dairy cows. At the onset of lactation the cow is not prepared for the sudden calcium requirement, which causes a drop in the blood calcium and the cow develops hypocalcaemia. Calcium is needed for the correct function of both nerves and muscles in the body. A cow suffering from milk fever can show a variety of clinical signs, such as being recumbent, having a reduced appetite and having cold extremities. In the worst cases of milk fever the cow can develop a comatose state and die. To cope with the loss of calcium the cow has several mechanisms in the body involving the kidneys, intestines and bones. These include increased absorption of calcium from the kidneys and intestines and a resorption of calcium from the bones. Milk fever has been studied for many decades and several risk factors have been identified, e.g. body condition score around calving, diet around calving, age, breed and production. The aim of this study was to analyze suspected and previously stated risk factors and their association with the incidence of milk fever. Data was collected through the milk recording scheme managed by VÄXA Sverige. All herds studied were selected based on the milking year 2015/16 (September-August) and had at least 40 calvings, 20% Swedish Holstein breed and 20% Swedish Red breed. Information about incidence of milk fever and the risk factors in these herds was retrieved from 2006/07 through 2015/16. The risk factors studied were breed, parity, previous milk fever cases, previous lactation length, previous dry period length, calving season, previous calving interval and information about milk production (ECM, fat, protein). A decreasing trend of the incidence of milk fever was observed throughout the years. All of the studied factors had an association with the incidence of milk fever. High risk cows were of Holstein breed, were of high parity, had suffered from milk fever in the previous lactation, had a long previous lactation length, had a dry period length of 70-89 days, calved in spring, had a long calving interval and had a high milk production. The determinant with the strongest association was parity, showing that cows of higher parity have clearly increased odds of developing milk fever. A sixth or higher parity cow had an odds ratio of 277.84 of developing milk fever compared to a first parity cow. The second most important determinant was milk fever in the previous lactation (OR=9.74). Several major factors, which previously have been shown to have an effect on milk fever incidence, could not be studied due to limitations in the available information. Furthermore, only univariable analyses were done although it is known that several of the studied determinants have an effect on each other

Room Temperature Ferrimagnetism, Magnetodielectric and Exchange Bias Effect in CoFeRhO4_4

Geometrically frustrated structures combined with competing exchange interactions that have different magnitudes are known ingredients for achieving exotic properties. Herein, we studied detailed structural, magnetic, thermal (specific heat), magneto-dielectric, and magnetic exchange bias properties of a mixed 3d - 4d spinel oxide with composition CoFeRhO$_4$. Detailed magnetization, heat capacity, and neutron powder diffraction studies (NPD) highlight long-range ferrimagnetic ordering with an onset at 355 K. The magnetic structure is established using a ferrimagnetic model (collinear-type) that has a propagation vector k = 0, 0, 0. The magneto-dielectric effect appears below the magnetic ordering temperature, and the exchange bias (EB) effect is observed in field cooled (FC) conditions below 355 K. The magneto-dielectric coupling in CoFeRhO$_4$ originates due to the frustration in the structure, collinear ferrimagnetic ordering, and uncompensated magnetic moments. The unidirectional anisotropy resulting from the uncompensated magnetic moments causes the room-temperature exchange bias effect. Remarkably, the appearance of technologically important properties (ferromagnetism, magnetodielectric effect, and EB) at room temperature in CoFeRhO$_4$ indicates its potential use in sensors or spintronics.Comment: 8 pages, 11 Figure