Magnetic Weyl semimetal phase in a Kagomé crystal Liu, D F; Liang, A J; Liu, E K ...
Science (American Association for the Advancement of Science),
09/2019, Letnik:
365, Številka:
6459
Journal Article
Recenzirano
Odprti dostop
Weyl semimetals are crystalline solids that host emergent relativistic Weyl fermions and have characteristic surface Fermi-arcs in their electronic structure. Weyl semimetals with broken time ...reversal symmetry are difficult to identify unambiguously. In this work, using angle-resolved photoemission spectroscopy, we visualized the electronic structure of the ferromagnetic crystal Co
Sn
S
and discovered its characteristic surface Fermi-arcs and linear bulk band dispersions across the Weyl points. These results establish Co
Sn
S
as a magnetic Weyl semimetal that may serve as a platform for realizing phenomena such as chiral magnetic effects, unusually large anomalous Hall effect and quantum anomalous Hall effect.
Summary
The potential interaction between chronic hepatitis B (CHB) and nonalcoholic fatty liver disease (NAFLD), two of the most prevalent liver diseases worldwide, has not been well defined. We ...performed liver stiffness (LS) and controlled attenuation parameter (CAP) measurements using transient elastography in 1202 CHB patients. Of these, 601 steatotic patients were matched with nonsteatotic controls in a 1:1 ratio by age, gender, nucleoside analogue treatment status, and treatment duration. Severe fibrosis was defined according to EASL‐ALEH criteria, and steatosis was defined as CAP ≥222 dB m−1. Anthropometric measurements and metabolic‐related parameters were recorded. The mean age of the 1202 patients (51.4% male) was 51.8 years. 696 patients (57.9%) were on nucleoside analogues for a median duration of 76.2 months. Among treatment‐naïve patients, median serum HBV DNA was lower in steatotic individuals than in controls (3.0 vs 3.4 log IU mL−1, P < .05), with this inverse relationship remaining significant in multivariate analysis (odds ratio 0.859, 95% CI 0.743‐0.994, P < .05). With increased steatosis severity, there was a stepwise decrease in median HBV DNA levels (3.1 and 2.6 log IU mL−1 in no steatosis and severe steatosis, respectively, P = .032). Steatosis was associated with a higher median LS (5.4 kPa vs 5.0 kPa, P < .001). Severe steatosis, when compared to mild/moderate steatosis, was associated with an increased percentage of severe fibrosis (23.2% and 12.6%, respectively, P = .005). We conclude that severe steatosis was associated with increased fibrosis in CHB patients. Increasing steatosis was independently associated with lower serum HBV DNA levels, suggesting its potential negative effects on viral replication.
Changes in two novel HBV serological markers, linearized hepatitis B surface antigen (HQ-HBsAg) and hepatitis B core-related antigen (HBcrAg), in the natural history of chronic hepatitis B (CHB) have ...not been well characterized. Serum HQ-HBsAg and HBcrAg levels of 404 Asian treatment-naïve CHB patients were analysed in a cross-sectional manner. Patients were categorized into five groups: immune tolerant (IT group, n = 52), immune clearance (IC group, n = 105), hepatitis B e antigen (HBeAg)-negative hepatitis (ENH group, n = 97), HBeAg-negative quiescent group (ENQ group, n = 95) and CHB with hepatitis B surface antigen (HBsAg) seroclearance (SC group, n = 55). HQ-HBsAg and HBcrAg were measured and correlated with HBV DNA, HBsAg, HBV genotype and clinical parameters. HQ-HBsAg showed good correlation with HBsAg, especially in the ENQ group (r = 0.874, p <0.001). Correlation of HQ-HBsAg with HBV DNA was less prominent and weakest in the ENH group (r = 0.268, p 0.008). HBcrAg correlated best with HBV DNA in the ENQ group (r = 0.537, p <0.001). In the ENQ group, 42.1% of patients had undetectable HBcrAg; this subgroup of patients, when compared with those with detectable HBcrAg, had significantly lower median HBV DNA (3.17/4.48 log IU/mL, p <0.001) and HBsAg (5.05/5.96 log mIU/mL, p <0.001) levels. Forty per cent of the SC group patients had detectable HQ-HBsAg and/or HBcrAg up to 42 months after HBsAg seroclearance. When comparing anti-HBs positivity and median time after HBsAg seroclearance in the SC group with and without detectable HQ-HBsAg/HBcrAg, there was no significant difference (22.7% and 36.4%, respectively, p 0.284, and 76.5 and 93.2 months, respectively, p 0.245). HQ-HBsAg and HBcrAg showed unique patterns of distribution throughout the five disease phases of CHB, including high detectability rates after HBsAg seroclearance, opening up different possibilities for their applicability.
Flower-like copper cobaltite (CuCo2O4) nanosheets anchored on graphite paper have been synthesized using a facile hydrothermal method followed by a postannealing treatment. Supercapacitor electrodes ...employing CuCo2O4 nanosheets exhibit an enhanced capacitance of 1131 F g–1 at a current density of 1 A g–1 compared with previously reported supercapacitor electrodes. The CuCo2O4 electrode delivers a specific capacitance of up to 409 F g–1 at a current density of as high as 50 A g–1, and a good long-term cycling stability, with 79.7% of its specific capacitance retained after 5000 cycles at 10 A g–1. Furthermore, the as-prepared CuCo2O4 nanosheets on graphite paper can be fabricated as electrodes and used as enzymeless glucose sensors, which exhibit good sensitivity (3.625 μA μM–1 cm–2) and an extraordinary linear response ranging up to 320 μM with a low detection limit (5 μM).
The coronavirus disease 2019 (COVID-19) outbreak caused by the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2 virus) has been sustained in China since December 2019, and has become a ...pandemic. The mental health of frontline medical staff is a concern. In this study, we aimed to identify the factors influencing medical worker anxiety in China during the COVID-19 outbreak. We conducted a cross-sectional study to estimate the prevalence of anxiety among medical staff in China from 10 February 2020 to 20 February 2020 using the Zung Self-rating Anxiety Scale (SAS) to assess anxiety, with the criteria of normal (⩽49), mild (50-59), moderate (60-70) and severe anxiety (⩾70). We used multivariable linear regression to determine the factors (e.g. having direct contact when treating infected patients, being a medical staff worker from Hubei province, being a suspect case) for anxiety. We also used adjusted models to confirm independent factors for anxiety after adjusting for gender, age, education and marital status. Of 512 medical staff in China, 164 (32.03%) had had direct contact treating infected patients. The prevalence of anxiety was 12.5%, with 53 workers suffering from mild (10.35%), seven workers suffering from moderate (1.36%) and four workers suffering from severe anxiety (0.78%). After adjusting for sociodemographic characteristics (gender, age, education and marital status), medical staff who had had direct contact treating infected patients experienced higher anxiety scores than those who had not had direct contact (β value = 2.33, confidence interval (CI) 0.65-4.00; P = 0.0068). A similar trend was observed in medical staff from Hubei province, compared with those from other parts of China (β value = 3.67, CI 1.44-5.89; P = 0.0013). The most important variable was suspect cases with high anxiety scores, compared to non-suspect cases (β value = 4.44, CI 1.55-7.33; P = 0.0028). In this survey of hospital medical workers during the COVID-19 outbreak in China, we found that study participants experienced anxiety symptoms, especially those who had direct clinical contact with infected patients; as did those in the worst affected areas, including Hubei province; and those who were suspect cases. Governments and healthcare authorities should proactively implement appropriate psychological intervention programmes, to prevent, alleviate or treat increased anxiety.
Topological Weyl semimetals (TWSs) represent a novel state of topological quantum matter which not only possesses Weyl fermions (massless chiral particles that can be viewed as magnetic monopoles in ...momentum space) in the bulk and unique Fermi arcs generated by topological surface states, but also exhibits appealing physical properties such as extremely large magnetoresistance and ultra-high carrier mobility. Here, by performing angle-resolved photoemission spectroscopy (ARPES) on NbP and TaP, we directly observed their band structures with characteristic Fermi arcs of TWSs. Furthermore, by systematically investigating NbP, TaP and TaAs from the same transition metal monopnictide family, we discovered their Fermiology evolution with spin-orbit coupling (SOC) strength. Our experimental findings not only reveal the mechanism to realize and fine-tune the electronic structures of TWSs, but also provide a rich material base for exploring many exotic physical phenomena (for example, chiral magnetic effects, negative magnetoresistance, and the quantum anomalous Hall effect) and novel future applications.
Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi2Te3 ...with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi2Te3 is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi2Te3 also points to promising potential for high-temperature spintronics applications.
Aims/hypothesis
FTO
harbours the strongest known obesity-susceptibility locus in Europeans. While there is growing evidence for a role for
FTO
in obesity risk in Asians, its association with type 2 ...diabetes, independently of BMI, remains inconsistent. To test whether there is an association of the
FTO
locus with obesity and type 2 diabetes, we conducted a meta-analysis of 32 populations including 96,551 East and South Asians.
Methods
All studies published on the association between
FTO
-rs9939609 (or proxy
r
2
> 0.98) and BMI, obesity or type 2 diabetes in East or South Asians were invited. Each study group analysed their data according to a standardised analysis plan. Association with type 2 diabetes was also adjusted for BMI. Random-effects meta-analyses were performed to pool all effect sizes.
Results
The
FTO
-rs9939609 minor allele increased risk of obesity by 1.25-fold/allele (
p
= 9.0 × 10
−19
), overweight by 1.13-fold/allele (
p
= 1.0 × 10
−11
) and type 2 diabetes by 1.15-fold/allele (
p
= 5.5 × 10
−8
). The association with type 2 diabetes was attenuated after adjustment for BMI (OR 1.10-fold/allele,
p
= 6.6 × 10
−5
). The
FTO
-rs9939609 minor allele increased BMI by 0.26 kg/m
2
per allele (
p
= 2.8 × 10
−17
), WHR by 0.003/allele (
p
= 1.2 × 10
−6
), and body fat percentage by 0.31%/allele (
p
= 0.0005). Associations were similar using dominant models. While the minor allele is less common in East Asians (12–20%) than South Asians (30–33%), the effect of
FTO
variation on obesity-related traits and type 2 diabetes was similar in the two populations.
Conclusions/interpretation
FTO
is associated with increased risk of obesity and type 2 diabetes, with effect sizes similar in East and South Asians and similar to those observed in Europeans. Furthermore,
FTO
is also associated with type 2 diabetes independently of BMI.
A total of 211 water samples were collected from 53 key sampling points from 5–10th July 2013 at four different depths (0m, 2m, 4m, 8m) and at different sites in the Huaihe River, Anhui, China. These ...points monitored for 18 parameters (water temperature, pH, TN, TP, TOC, Cu, Pb, Zn, Ni, Co, Cr, Cd, Mn, B, Fe, Al, Mg, and Ba). The spatial variability, contamination sources and health risk of trace elements as well as the river water quality were investigated. Our results were compared with national (CSEPA) and international (WHO, USEPA) drinking water guidelines, revealing that Zn, Cd and Pb were the dominant pollutants in the water body. Application of different multivariate statistical approaches, including correlation matrix and factor/principal component analysis (FA/PCA), to assess the origins of the elements in the Huaihe River, identified three source types that accounted for 79.31% of the total variance. Anthropogenic activities were considered to contribute much of the Zn, Cd, Pb, Ni, Co, and Mn via industrial waste, coal combustion, and vehicle exhaust; Ba, B, Cr and Cu were controlled by mixed anthropogenic and natural sources, and Mg, Fe and Al had natural origins from weathered rocks and crustal materials. Cluster analysis (CA) was used to classify the 53 sample points into three groups of water pollution, high pollution, moderate pollution, and low pollution, reflecting influences from tributaries, power plants and vehicle exhaust, and agricultural activities, respectively. The results of the water quality index (WQI) indicate that water in the Huaihe River is heavily polluted by trace elements, so approximately 96% of the water in the Huaihe River is unsuitable for drinking. A health risk assessment using the hazard quotient and index (HQ/HI) recommended by the USEPA suggests that Co, Cd and Pb in the river could cause non-carcinogenic harm to human health.
Display omitted
•Zn, Cd and Pb were identified as the dominant pollutants in the water body.•Approximately 96% of the waters in the Huaihe River were unsuitable for drinking.•Co, Cd and Pb in the river could pose potential non-carcinogenic effects on human health.
Three-dimensional (3D) topologicalWeyl semimetals (TWSs) represent a state of quantum matter with unusual electronic structures that resemble both a '3D graphene' and a topological insulator. Their ...electronic structure displays pairs of Weyl points (through which the electronic bands disperse linearly along all three momentum directions) connected by topological surface states, forming a unique arc-like Fermi surface (FS). Each Weyl point is chiral and contains half the degrees of freedom of a Dirac point, and can be viewed as a magnetic monopole in momentum space. By performing angle-resolved photoemission spectroscopy on the non-centrosymmetric compound TaAs, here we report its complete band structure, including the unique Fermi-arc FS and linear bulk band dispersion across the Weyl points, in agreement with the theoretical calculations1, 2. This discovery not only confirms TaAs as a 3DTWS, but also provides an ideal platform for realizing exotic physical phenomena (for example, negative magnetoresistance, chiral magnetic effects and the quantum anomalous Hall effect) which may also lead to novel future applications.
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