The Effect of Hyperthermia on the Immune Response of Vannamei Shrimp Infected with IMNV

The purpose of this study was to determine the effect of hyperthermia on the immune response of shrimp infected by IMNV. Vannamei shrimp were challenged with IMNV and reared at temperatures 30ºC (Sk30), 31ºC (S31), 32ºC (S32) and 33ºC (S33) repectively. The temperature of shrimp without IMNV infection was 300C as control. During the study, shrimp immune response measurements were Total Hemocyte Count (THC), Differential Hemocyte Count (DHC), Respiratory Burst (RB) activity and Phenoloksidase (PO) activity. Generally, the results showed that the response of shrimp decreased along with hyperthermic condition. Shrimp infected with IMNV, decreased immune response especially at temperatures of 32ºC and 33ºC

High magnetic field scales and critical currents in SmFeAs(O,F) crystals: promising for applications

Superconducting technology provides most sensitive field detectors, promising implementations of qubits and high field magnets for medical imaging and for most powerful particle accelerators. Thus, with the discovery of new superconducting materials, such as the iron pnictides, exploring their potential for applications is one of the foremost tasks. Even if the critical temperature Tc is high, intrinsic electronic properties might render applications rather difficult, particularly if extreme electronic anisotropy prevents effective pinning of vortices and thus severely limits the critical current density, a problem well known for cuprates. While many questions concerning microscopic electronic properties of the iron pnictides have been successfully addressed and estimates point to a very high upper critical field, their application potential is less clarified. Thus we focus here on the critical currents, their anisotropy and the onset of electrical dissipation in high magnetic fields up to 65 T. Our detailed study of the transport properties of optimally doped SmFeAs(O,F) single crystals reveals a promising combination of high (>2 x 10^6 A/cm^2) and nearly isotropic critical current densities along all crystal directions. This favorable intragrain current transport in SmFeAs(O,F), which shows the highest Tc of 54 K at ambient pressure, is a crucial requirement for possible applications. Essential in these experiments are 4-probe measurements on Focused Ion Beam (FIB) cut single crystals with sub-\mu\m^2 cross-section, with current along and perpendicular to the crystallographic c-axis and very good signal-to-noise ratio (SNR) in pulsed magnetic fields. The pinning forces have been characterized by scaling the magnetically measured "peak effect"

Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor

The latest discovery of high temperature superconductivity signature in single-layer FeSe is significant because it is possible to break the superconducting critical temperature ceiling (maximum Tc~55 K) that has been stagnant since the discovery of Fe-based superconductivity in 2008. It also blows the superconductivity community by surprise because such a high Tc is unexpected in FeSe system with the bulk FeSe exhibiting a Tc at only 8 K at ambient pressure which can be enhanced to 38 K under high pressure. The Tc is still unusually high even considering the newly-discovered intercalated FeSe system A_xFe_{2-y}Se_2 (A=K, Cs, Rb and Tl) with a Tc at 32 K at ambient pressure and possible Tc near 48 K under high pressure. Particularly interesting is that such a high temperature superconductivity occurs in a single-layer FeSe system that is considered as a key building block of the Fe-based superconductors. Understanding the origin of high temperature superconductivity in such a strictly two-dimensional FeSe system is crucial to understanding the superconductivity mechanism in Fe-based superconductors in particular, and providing key insights on how to achieve high temperature superconductivity in general. Here we report distinct electronic structure associated with the single-layer FeSe superconductor. Its Fermi surface topology is different from other Fe-based superconductors; it consists only of electron pockets near the zone corner without indication of any Fermi surface around the zone center. Our observation of large and nearly isotropic superconducting gap in this strictly two-dimensional system rules out existence of node in the superconducting gap. These results have provided an unambiguous case that such a unique electronic structure is favorable for realizing high temperature superconductivity

Two-dome structure in electron-doped iron arsenide superconductors

Iron arsenide superconductors based on the material LaFeAsO1-xFx are characterized by a two-dimensional Fermi surface (FS) consisting of hole and electron pockets yielding structural and antiferromagnetic transitions at x = 0. Electron doping by substituting O2- with F- suppresses these transitions and gives rise to superconductivity with a maximum Tc = 26 K at x = 0.1. However, the over-doped region cannot be accessed due to the poor solubility of F- above x = 0.2. Here we overcome this problem by doping LaFeAsO with hydrogen. We report the phase diagram of LaFeAsO1-xHx (x < 0.53) and, in addition to the conventional superconducting dome seen in LaFeAsO1-xFx, we find a second dome in the range 0.21 < x < 0.53, with a maximum Tc of 36 K at x = 0.3. Density functional theory calculations reveal that the three Fe 3d bands (xy, yz, zx) become degenerate at x = 0.36, whereas the FS nesting is weakened monotonically with x. These results imply that the band degeneracy has an important role to induce high Tc.Comment: 31 pages, 4 figures, 1 table and supplementary informatio

Superconductivity above 30 K in alkali-metal-doped hydrocarbon

The recent discovery of superconductivity with a transition temperature (Tc) at 18 K in Kxpicene has extended the possibility of high-Tc superconductors in organic materials. Previous experience based on similar hydrocarbons, like alkali-metal doped phenanthrene, suggested that even higher transition temperatures might be achieved in alkali-metals or alkali-earth-metals doped such polycyclic-aromatic-hydrocarbons (PAHs), a large family of molecules composed of fused benzene rings. Here we report the discovery of high-Tc superconductivity at 33 K in K-doped 1,2:8,9-dibenzopentacene (C30H18). To our best knowledge, it is higher than any Tc reported previously for an organic superconductor under ambient pressure. This finding provides an indication that superconductivity at much higher temperature may be possible in such PAHs system and is worthy of further exploration

Winter Time Concentrations and Size Distribution of Bioaerosols in Different Residential Settings in the UK

The total concentration and size distribution of bioaerosols in three different types of housing (single room in shared accommodation [type I], single bedroom flat in three-storey building [type II] and two- or threebedroom detached houses [type III]) was assessed during the winter. This research was an extension of a previous study carried out in the summer. The measurement campaign was undertaken in winter 2008 and 30 houses were sampled. Samples were taken from kitchens, living rooms, corridors (only in housing type I) and outdoors with an Anderson 6 stage viable impactor. In housing type I, the total geometric mean concentration was highest in the corridor for both bacteria and fungi (3,171 and 1,281 CFU/m3, respectively). In type II residences, both culturable bacteria and fungi were greatest in the living rooms (3,487 and 833 CFU/m3, respectively). The living rooms in type III residences had largest number of culturable bacteria (1,361 CFU/m3) while fungi were highest in kitchens (280 CFU/m3). The concentrations of culturable bacteria and fungi were greater in mouldy houses than non-mouldy houses. A considerable variation was seen in the size distribution of culturable bacteria in type I residences compared to types II and III. For all housing types more than half of culturable bacterial and fungal aerosol were respirable (<4.7 μm) and so have the potential to penetrate into lower respiratory system. Considerable variation in concentration and size distribution within different housing types in the same geographical region highlights the impact of differences in design, construction, use and management of residential built environment on bioaerosols levels and consequent varied risk of population exposure to airborne biological agents. © Springer Science+Business Media B.V. 2012

Observation of superconductivity at 30 K~46 K in AxFe2Se2 (A = Li, Na, Ba, Sr, Ca, Yb, and Eu)

New iron selenide superconductors by intercalating smaller-sized alkali metals (Li, Na) and alkaline earths using high-temperature routes have been pursued ever since the discovery of superconductivity at about 30 K in KFe2Se2, but all have failed so far. Here we demonstrate that a series of superconductors with enhanced Tc=30~46 K can be obtained by intercalating metals, Li, Na, Ba, Sr, Ca, Yb, and Eu in between FeSe layers by the ammonothermal method at room temperature. Analysis on their powder X-ray diffraction patterns reveals that all the main phases can be indexed based on body-centered tetragonal lattices with a~3.755-3.831 {\AA} while c~15.99-20.54 {\AA}. Resistivities show the corresponding sharp transitions at 45 K and 39 K for NaFe2Se2 and Ba0.8Fe2Se2, respectively, confirming their bulk superconductivity. These findings provide a new starting point for studying the properties of these superconductors and an effective synthetic route for the exploration of new superconductors as well.Comment: 22 pages, 5 figure

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides

High-temperature superconductivity in iron-arsenic materials (pnictides) near an antiferromagnetic phase raises the possibility of spin-fluctuation-mediated pairing. However, the interplay between antiferromagnetic fluctuations and superconductivity remains unclear in the underdoped regime, which is closer to the antiferromagnetic phase. Here we report that the superconducting gap of the underdoped pnictides scales linearly with the transition temperature, and that a distinct pseudogap coexisting with the SC gap develops on underdoping. This pseudogap occurs on Fermi surface sheets connected by the antiferromagnetic wavevector, where the superconducting pairing is stronger as well, suggesting that antiferromagnetic fluctuations drive both the pseudogap and superconductivity. Interestingly, we found that the pseudogap and the spectral lineshape vary with the Fermi surface quasi-nesting conditions in a fashion that shares similarities with the nodal-antinodal dichotomous behaviour observed in underdoped copper oxide superconductors.Comment: Main Manuscript: 19 pages, 3 figures; Supplementary Information: 10 pages, 7 figure

Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure

In this letter, we report that the superconductivity transition temperature in beta-Fe1.01Se increases from 8.5 to 36.7 K under applied pressure of 8.9 GPa. It then decreases at higher pressure. A dramatic change in volume is observed at the same time Tc rises, due to a collapse of the separation between the Fe2Se2 layers. A clear transition to a linear resistivity normal state is seen on cooling at all pressures. No static magnetic ordering is observed for the whole p-T phase diagram. We also report that at higher pressure (starting around 7 GPa and completed at 38 GPa), Fe1.01Se transforms to a hexagonal NiAs-type structure and displays non-magnetic, insulating behavior. The inclusion of electron correlation in band structure caculations is necessary to describe this behavior, signifying that such correlations are important in this chemical system. Our results strongly support unconventional superconductivity in beta-Fe1.01Se.Comment: 17 pages, 4 figure