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.
Background and purpose
Physical activity is associated with a reduced incidence of first‐time stroke. However, few studies have examined the effect of pre‐stroke physical activity on post‐stroke ...complications and clinical outcomes.
Methods
A total of 39 835 cases of stroke registered in the nationwide stroke registry system of Taiwan between 2006 and 2009 were analyzed according to five levels of severity as determined by National Institutes of Health Stroke Scale score upon hospital admission. Pre‐stroke physical activity was defined in the Taiwan Stroke Registry as dedicated leisure‐time physical activity for at least 30 min/day for 3 days/week for more than 6 months. A Cox model was used to compare complications and outcomes between active and inactive groups.
Results
The active and inactive groups were similar in age distribution and stroke type distribution, but the active group had better National Institutes of Health Stroke Scale scores upon admission. The active group also had significantly fewer post‐stroke complications. Active patients had lower hospital mortality and better functional outcomes upon discharge as per the modified Rankin Scale. Improved functional status in the active group was significant at 1, 3 and 6 months post‐stroke.
Conclusion
Dedicated leisure‐time physical activity for at least 30 min/day, at least three times per week for more than 6 months was associated with decreased stroke severity, fewer post‐stroke complications, lower mortality and better outcomes.
To explore the characteristics of Helicobacter pylori resistance in China and the association between antibiotic resistance and several clinical factors.
H. pylori strains were collected from ...patients in 13 provinces or cities in China between 2010 and 2016. Demographic data including type of disease, geographic area, age, gender and isolation year were collected to analyse their association with antibiotic resistance. Antibiotic resistance was detected using the Etest test and the Kirby-Bauer disc diffusion method.
H. pylori were successfully cultured from 1117 patients. The prevalence of metronidazole, clarithromycin (CLA), azithromycin, levofloxacin (LEV), moxifloxacin, amoxicillin (AMO), tetracycline and rifampicin resistance was 78.2, 22.1, 23.3, 19.2, 17.2, 3.4, 1.9 and 1.5%, respectively. No resistance to furazolidone was observed. The resistance rates to LEV and moxifloxacin were higher in strains isolated from patients with gastritis compared to those with duodenal ulcer and among women. Compared to patients ≥40 years old, younger patients exhibited lower resistance rates to CLA, azithromycin, LEV and moxifloxacin. The resistance rates to CLA and AMO were higher in strains isolated more recently, and we also found that the prevalence of resistance to metronidazole, CLA, azithromycin and AMO were significantly different among different regions of China.
The resistance rates to metronidazole, CLA and LEV were high in China. Patient age, gender, disease and location were associated with the resistance of H. pylori to some antibiotics. Furazolidone, AMO and tetracycline are better choices for H. pylori treatment in China.
The associations between long-term risk of hepatocellular carcinoma (HCC) and spontaneous seroclearance of HBV e antigen (HBeAg), HBV DNA and HBV surface antigen (HBsAg) have never been examined by a ...prospective study using serially measured seromarkers. This study aimed to assess the importance of spontaneous HBeAg, HBV DNA and HBsAg seroclearance in the prediction of HCC risk.
This study included 2946 HBsAg seropositive individuals who were seronegative for antibodies against HCV and free of liver cirrhosis. Serial serum samples collected at study entry and follow-up health examinations were tested for HBeAg, HBV DNA and HBsAg. Cox proportional hazards models were used to calculate the HRs of developing HCC after seroclearance of HBV markers.
The HR (95% CI) of developing HCC after seroclearance of HBeAg, HBV DNA and HBsAg during follow-up was 0.63 (0.38 to 1.05), 0.24 (0.11 to 0.57) and 0.18 (0.09 to 0.38), respectively, after adjustment for age, gender and serum level of alanine aminotransferase at study entry. High HBV DNA levels at the seroclearance of HBeAg (mean±SD, 4.35±1.64 log10 IU/mL) may explain the non-significant association between HBeAg seroclearance and HCC risk. Among HBeAg seronegative participants with detectable serum HBV DNA at study entry, the lifetime (30-75-years-old) cumulative incidence of HCC was 4.0%, 6.6% and 14.2%, respectively, for those with seroclearance of both HBV DNA and HBsAg, seroclearance of HBV DNA only, and seroclearance of neither.
Spontaneous seroclearance of HBV DNA and HBsAg are important predictors of reduced HCC risk.
We use single-cycle THz fields and the femtosecond magneto-optical Kerr effect to, respectively, excite and probe the magnetization dynamics in two thin-film ferromagnets with different lattice ...structures: crystalline Fe and amorphous CoFeB. We observe Landau-Lifshitz-torque magnetization dynamics of comparable magnitude in both systems, but only the amorphous sample shows ultrafast demagnetization caused by the spin-lattice depolarization of the THz-induced ultrafast spin current. Quantitative modeling shows that such spin-lattice scattering events occur on similar time scales than the conventional spin conserving electronic scattering (∼30 fs). This is significantly faster than optical laser-induced demagnetization. THz conductivity measurements point towards the influence of lattice disorder in amorphous CoFeB as the driving force for enhanced spin-lattice scattering.
The metabolic functions of androgen receptor (AR) in normal prostate are circumvented in prostate cancer (PCa) to drive tumor growth, and the AR also can acquire new growth-promoting functions during ...PCa development and progression through genetic and epigenetic mechanisms. Androgen deprivation therapy (ADT, surgical or medical castration) is the standard treatment for metastatic PCa, but patients invariably relapse despite castrate androgen levels (castration-resistant PCa, CRPC). Early studies from many groups had shown that AR was highly expressed and transcriptionally active in CRPC, and indicated that steroids from the adrenal glands were contributing to this AR activity. More recent studies showed that CRPC cells had increased expression of enzymes mediating androgen synthesis from adrenal steroids, and could synthesize androgens de novo from cholesterol. Phase III clinical trials showing a survival advantage in CRPC for treatment with abiraterone (inhibitor of the enzyme CYP17A1 required for androgen synthesis that markedly reduces androgens and precursor steroids) and for enzalutamide (new AR antagonist) have now confirmed that AR activity driven by residual androgens makes a major contribution to CRPC, and led to the recent Food and Drug Administration approval of both agents. Unfortunately, patients treated with these agents for advanced CRPC generally relapse within a year and AR appears to be active in the relapsed tumors, but the molecular mechanisms mediating intrinsic or acquired resistance to these AR-targeted therapies remain to be defined. This review outlines AR functions that contribute to PCa development and progression, the roles of intratumoral androgen synthesis and AR structural alterations in driving AR activity in CRPC, mechanisms of action for abiraterone and enzalutamide, and possible mechanisms of resistance to these agents.
Abstract
Topological Weyl semimetal (TWS), a new state of quantum matter, has sparked enormous research interest recently. Possessing unique Weyl fermions in the bulk and Fermi arcs on the surface, ...TWSs offer a rare platform for realizing many exotic physical phenomena. TWSs can be classified into type-I that respect Lorentz symmetry and type-II that do not. Here, we directly visualize the electronic structure of MoTe
2
, a recently proposed type-II TWS. Using angle-resolved photoemission spectroscopy (ARPES), we unravel the unique surface Fermi arcs, in good agreement with our
ab initio
calculations that have nontrivial topological nature. Our work not only leads to new understandings of the unusual properties discovered in this family of compounds, but also allows for the further exploration of exotic properties and practical applications of type-II TWSs, as well as the interplay between superconductivity (MoTe
2
was discovered to be superconducting recently) and their topological order.
We present Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) radio observations of GW170817, the first Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo ...gravitational wave (GW) event from a binary neutron star merger and the first GW event with an electromagnetic (EM) counterpart. Our data include the first observations following the discovery of the optical transient at both the centimeter (13.7 hr post-merger) and millimeter (2.41 days post-merger) bands. We detect faint emission at 6 GHz at 19.47 and 39.23 days after the merger, but not in an earlier observation at 2.46 days. We do not detect cm/mm emission at the position of the optical counterpart at frequencies of 10-97.5 GHz at times ranging from 0.6 to 30 days post-merger, ruling out an on-axis short gamma-ray burst (SGRB) for energies 10 48 erg. For fiducial SGRB parameters, our limits require an observer viewer angle of 20°. The radio and X-ray data can be jointly explained as the afterglow emission from an SGRB with a jet energy of ∼ 10 49 - 10 50 erg that exploded in a uniform density environment with n ∼ 10 − 4 - 10 − 2 cm−3, viewed at an angle of ∼20°-40° from the jet axis. Using the results of our light curve and spectral modeling, in conjunction with the inference of the circumbinary density, we predict the emergence of late-time radio emission from the deceleration of the kilonova (KN) ejecta on a timescale of ∼5-10 years that will remain detectable for decades with next-generation radio facilities, making GW170817 a compelling target for long-term radio monitoring.
Resveratrol, a phytochemical found in various plants and Chinese herbs, is associated with multiple tumor-suppressing activities, has been tested in clinical trials. However, the molecular mechanisms ...involved in resveratrol-mediated tumor suppressing activities are not yet completely defined. Here, we showed that treatment with resveratrol inhibited cell mobility through induction of the mesenchymal-epithelial transition (MET) in lung cancer cells. We also found that downregulation of FOXC2 (forkhead box C2) is critical for resveratrol-mediated suppression of tumor metastasis in an in vitro and in vivo models. We also identified a signal cascade, namely, resveratrol-∣miRNA-520h-∣PP2A/C-∣Akt → NF-κB → FOXC2, in which resveratrol inhibited the expression of FOXC2 through regulation of miRNA-520h-mediated signal cascade. This study identified a new miRNA-520h-related signal cascade involved in resveratrol-mediated tumor suppression activity and provide the clinical significances of miR-520h, PP2A/C and FOXC2 in lung cancer patients. Our results indicated a functional link between resveratrol-mediated miRNA-520h regulation and tumor suppressing ability, and provide a new insight into the role of resveratrol-induced molecular and epigenetic regulations in tumor suppression.
This study comprehensively investigates the changing biodistribution of fluorescent-labelled polystyrene latex bead nanoparticles in a mouse model of inflammation. Since inflammation alters systemic ...circulatory properties, increases vessel permeability and modulates the immune system, we theorised that systemic inflammation would alter nanoparticle distribution within the body. This has implications for prospective nanocarrier-based therapies targeting inflammatory diseases. Low dose lipopolysaccharide (LPS), a bacterial endotoxin, was used to induce an inflammatory response, and 20 nm, 100 nm or 500 nm polystyrene nanoparticles were administered after 16 hours. HPLC analysis was used to accurately quantify nanoparticle retention by each vital organ, and tissue sections revealed the precise locations of nanoparticle deposition within key tissues. During inflammation, nanoparticles of all sizes redistributed, particularly to the marginal zones of the spleen. We found that LPS-induced inflammation induces splenic macrophage polarisation and alters leukocyte uptake of nanoparticles, with size-dependent effects. In addition, spleen vasculature becomes significantly more permeable following LPS treatment. We conclude that systemic inflammation affects nanoparticle distribution by multiple mechanisms, in a size dependent manner.
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