The discovery of high-temperature superconductivity in iron pnictides raised the possibility of an unconventional superconducting mechanism in multiband materials. The observation of Fermi-surface ...(FS)-dependent nodeless superconducting gaps suggested that inter-FS interactions may play a crucial role in superconducting pairing. In the optimally hole-doped Ba₀.₆K₀.₄Fe₂As₂, the pairing strength is enhanced simultaneously (2Δ/Tcalmost equal to7) on the nearly nested FS pockets, i.e., the inner hole-like (α) FS and the 2 hybridized electron-like FSs, whereas the pairing remains weak (2Δ/Tcalmost equal to3.6) in the poorly nested outer hole-like (β) FS. Here, we report that in the electron-doped BaFe₁.₈₅Co₀.₁₅As₂, the FS nesting condition switches from the α to the β FS due to the opposite size changes for hole- and electron-like FSs upon electron doping. The strong pairing strength (2Δ/Tcalmost equal to6) is also found to switch to the nested β FS, indicating an intimate connection between FS nesting and superconducting pairing, and strongly supporting the inter-FS pairing mechanism in the iron-based superconductors.
Cytokine storm syndrome (CSS) is a critical clinical condition induced by a cascade of cytokine activation, characterized by overwhelming systemic inflammation, hyperferritinaemia, haemodynamic ...instability and multiple organ failure (MOF). At the end of 2019, the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) emerged in Wuhan, China, and rapidly developed into a global pandemic. More and more evidence shows that there is a dramatic increase of inflammatory cytokines in patients with COVID‐19, suggesting the existence of cytokine storm in some critical illness patients. Here, we summarize the pathogenesis, clinical manifestation of CSS, and highlight the current understanding about the recognition and potential therapeutic options of CSS in COVID‐19.
Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances
. It has long been speculated that magnetars are the engine powering ...repeating bursts from FRB sources
, but no convincing evidence has been collected so far
. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft γ-ray bursts
. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft γ-ray/hard-X-ray flare
. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-γ-ray repeater (SGR) bursts were detected in γ-ray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.
AIMS: The aim of this study was to characterize anaerobic ammonium oxidation (anammox) community in sediments of the Dongjiang River, a drinking water source of Hong Kong. METHODS AND RESULTS: The ...diversity and distribution of the anammox community were investigated based on a comparative analyses of 16S rRNA and hydrazine oxidation (hzo) genes of anammox bacteria. Candidatus Brocadia and two new anammox bacterial clusters were detected based on phylogenetic analysis of 16S rRNA genes. In contrast, the targeting of hzo genes indicated the presence of only Candidatus Jettenia with four different clusters. It was found that the sequence diversities of hzo genes were higher than those of the 16S rRNA genes. The abundance of anammox bacteria varied significantly among the sediment samples based on qPCR. Pearson correlation analysis indicated that nitrite concentration was the key factor influencing the abundance of anammox bacteria. The redundance analysis (RDA) confirmed that the combination of the contents of nitrite and nitrate, and the ratio of total nitrogen vs total carbon (TN/TC) had significant impact on the anammox bacterial community structure. CONCLUSIONS: The results revealed that the diverse anammox bacteria were present in sediments of the Dongjiang River, and the community structures were associated with varied environmental factors caused by urban pollutant invasion. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report about the distribution of anammox bacterial community in sediments of the Dongjiang River, which provides helpful information of anammox niche specificity and influencing factors in the river ecosystem.
Discovery of magnetic Weyl fermions: Dirac fermions split into pairs of Weyl fermions by slow magnetic fluctuations.
Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in ...which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd
2
As
2
. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.
Graphical abstract Highlight ► Cat urine odor induces fear behavior in rats. ► Injection muscimol into the BNST blocks the freezing induced by cat urine odor. ► The BNST, not BLA, is essential for ...innate fear responses in rats.
Hong Kong imposed a partial restriction on application of organotin-based antifouling paints in 1992. Since September 2008, the International Maritime Organization prohibited the use of such ...antifouling systems on all sea-going vessels globally. Therefore, it is anticipated a gradual reduction of organotin contamination in Hong Kong's marine waters. Using the rock shell Reishia clavigera as a biomonitor, we evaluated the organotin contamination along Hong Kong's coastal waters over the past two decades (1990-2015). In 2010 and 2015, adult R. clavigera were examined for imposex status and analysed for tissue concentrations of six organotins. We consistently found 100% imposex incidence in female R. clavigera across all sites. Tissue triphenyltin (TPT) concentrations were high in most samples. A probabilistic risk assessment showed that there were over 69% of chance that local R. clavigera would be at risk due to exposure to phenyltins. Comparing with those of previous surveys (2004-2010), both imposex levels and tissue concentrations of organotins did not decline, while the ecological risks due to exposure to organotins were increasing. We also observed high concentrations of monobutyltin and TPT in seawater and sediment from locations with intense shipping activities and from stormwater or sewage discharge. Overall, organotins are still prevalent in Hong Kong's marine waters showing that the global convention alone may be inadequate in reducing organotin contamination in a busy international port like Hong Kong. Appropriate management actions should be taken to control the use and release of organotins in Hong Kong and South China.
Purpose
To investigate whether growth hormone (GH) could improve pregnancy rates of patients with thin endometrium by clinical study and laboratory experiments.
Materials and methods
Ninety-three ...patients were randomized to either the GH-received group (40) or the routine exogenous administration of estrogens control group (53) for clinical study. The human endometrial carcinoma cell line RL95-2 was used for testing the role of GH with Western blot and real-time PCR by exposure to various concentrations of GH (0.1 nM,1 nM,10 nM,100 nM).
Results
Patients treated with GH had a significantly (
P
< 0.05) greater endometrium thickness on day 3 (7.87±0.72 vs 6.34±0.86), higher implantation rates (24.4% vs 10.5%) and greater clinical pregnancy rates (42.5% vs 18.9%) compared with the control group. No adverse events were associated with the use of GH. Administration of GH significantly up-regulated the expression of VEGF, ItgB3 and IGF-I expression in RL95-2 cells at both mRNA and protein levels (
P
< 0.05). AG490, an inhibitor of JAK2, nearly completely inhibited the up-regulative effect of GH through the JAK2-STAT5 pathway, and GH-induced effects could be mediated through autocrine IGF-I together with its hepatic counterpart. IGF-I mRNA was detected in the RL95-2 cells.
Conclusion
GH may improve pregnancy outcomes of patients with thin endometrium who undergo frozen embryo transfer by acting on human endometrial cells to promote proliferation and vascularization and to up-regulate receptivity-related molecular expression.
Abstract
Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum-spin-Hall (QSH) effect, but experimental realization of ...such systems with a large band gap suitable for room-temperature applications has proven difficult. Here, we report the successful growth on bilayer graphene of a quasi-freestanding WSe
2
single layer with the 1
T
′ structure that does not exist in the bulk form of WSe
2
. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we observe a gap of 129 meV in the 1
T
′ layer and an in-gap edge state located near the layer boundary. The system′s 2D TI characters are confirmed by first-principles calculations. The observed gap diminishes with doping by Rb adsorption, ultimately leading to an insulator–semimetal transition. The discovery of this large-gap 2D TI with a tunable band gap opens up opportunities for developing advanced nanoscale systems and quantum devices.
PDF
