Above 400 K Robust Perpendicular Ferromagnetic Phase in a Topological Insulator

The quantum anomalous Hall effect (QAHE) that emerges under broken time-reversal symmetry in topological insulators (TI) exhibits many fascinating physical properties for potential applications in nano-electronics and spintronics. However, in transition-metal doped TI, the only experimentally demonstrated QAHE system to date, the effect is lost at practically relevant temperatures. This constraint is imposed by the relatively low Curie temperature (Tc) and inherent spin disorder associated with the random magnetic dopants. Here we demonstrate drastically enhanced Tc by exchange coupling TI to Tm3Fe5O12, a high-Tc magnetic insulator with perpendicular magnetic anisotropy. Signatures that the TI surface states acquire robust ferromagnetism are revealed by distinct squared anomalous Hall hysteresis loops at 400 K. Point-contact Andreev reflection spectroscopy confirms that the TI surface is indeed spin-polarized. The greatly enhanced Tc, absence of spin disorder, and perpendicular anisotropy are all essential to the occurrence of the QAHE at high temperatures

A controllable superconducting electromechanical oscillator with a suspended membrane

We fabricate a microscale electromechanical system, in which a suspended superconducting membrane, treated as a mechanical oscillator, capacitively couples to a superconducting microwave resonator. As the microwave driving power increases, nonmonotonic dependence of the resonance frequency of the mechanical oscillator on the driving power has been observed. We also demonstrate the optical switching of the resonance frequency of the mechanical oscillator. Theoretical models for qualitative understanding of our experimental observations are presented. Our experiment may pave the way for the application of a mechanical oscillator with its resonance frequency controlled by the electromagnetic and/or optical fields, such as a microwave-optical interface and a controllable element in a superqubit-mechanical oscillator hybrid system.Comment: 8 pages,4 figure

Secondary Impact of Manganese on the Catalytic Properties of Nitrogen-Doped Graphene in the Hydrogen Evolution Reaction

Catalysts play a key role in hydrogen production as green energy carriers. We show herein for the first time that manganese impurities in graphene can improve the catalytic activity of synthesized N‐doped graphene (NG) for the hydrogen evolution reaction in acid media by influencing the ratio of different N‐functionalities. A 122 mV improvement in the overpotential was found following the Mn impregnation of graphene. Transmission electron microscopy images confirmed the formation of manganese oxide nanoparticles on the NG sheets. X‐ray photoelectron spectroscopy revealed structural alteration in favor of higher quantities of quaternary and pyrrolic nitrogen functionalities, from approximately 37 % in NG to 84 % in the Mn‐inserted‐doped graphene catalyst. This enhanced catalytic performance, based on density functional theory calculations in the literature, was attributed to an increase in the number of active sites with higher activity

Community of endophytic fungi from the medicinal and edible plant Fagopyrum tataricum and their antimicrobial activity

Purpose: To isolate and identify the fungal endophytes of Fagopyrum tataricum and assess their antimicrobial activity.Methods: The fungal isolates were identified according to their morphological  characters and internal transcribed spacer (ITS) sequence analysis. Both broth-dilution-colorimetric assay and spore germination test were employed to assess the antimicrobial activity of fungal mycelia extracts.Results: A total of 72 endophytic fungal isolates were successfully obtained from the healthy tissues of F. tataricum. On the basis of their morphological and  molecular characteristics, thirteen distinct fungal isolates were identified, and belonged to Alternaria, Bionectria, Botryosphaeria, Fusarium, Guignardia, Nectria, Neonectria, Phomopsis, Pseudocercospora and Verticillium spp. Of these, Pseudocercospora owned the maximum colonization frequency (15.3 %), next for Alternaria (12.5 %) and Neonectria (11.1 %). Through antimicrobial screening assays, six endophytes (Fataf-4, 6, 9, 11, 12 and 15) were active against Bacillus subtilis, Staphylococcus aureus, Agrobacterium tumefaciens, Escherichia coli and Pseudomonas lachrymans, and their minimal inhibitory concentration (MIC) ranged from 0.125 to 2.00 mg/mL. Furthermore, the endophytes, Fataf-9 and Fataf-11, also displayed strong inhibitory activity on the spore germination of F. oxysporum f. sp. vasinfectum and F. oxysporum f. sp. cucumerinum, and their median effective inhibitory concentration (IC50) was 0.356, 0.463, 0.451 and 0.489 mg/mL, respectively.Conclusion: The endophytic fungi of F. tataricum appear to be diverse and promising in their antimicrobial activity, and may represent a potential source of antibiotics for agriculture and/or pharmaceutical applications.Keywords: Endophytic fungi, Fagopyrum tataricum, Diversity, Antimicrobial activity, Antibiotics, Pseudocercospor

2,4,5-Tris(pyridin-4-yl)-1H-imidazole monohydrate

In the crystal structure of the title compound, C18H13N5·H2O, adjacent mol­ecules are linked by O—H⋯N and N—H⋯O hydrogen bonds, generating a chain propagating along [001]

Prediction of the Lymph Node Status in Patients with Intrahepatic Cholangiocarcinoma: Analysis of 320 Surgical Cases

Purpose: This study was conducted to identify factors involved in lymph node metastasis (LNM) and evaluate their role in predicting LNM in clinically lymph node negative (clinical stage I–III) intrahepatic cholangiocarcinoma (ICC). Materials and Methods: We selected 320 patients who were diagnosed with ICC with no apparent clinical LNM (T1–3N0M0). Age, gender, tumor boundary, histological differentiation, tumor size, and carbohydrate antigen 19-9 value were the studied factors. Univariate and multivariate logistic analysis were conducted. Receiver operating characteristics curve analysis was used to test the predicting value of each factor and a test which combined the associated factors was used to predict LNM. Results: LNM was observed in 76 cases (76/320, 23.8%). Univariate and multivariate analysis showed that histological differentiation as well as tumor boundary and tumor size significantly correlated with LNM. The sensitivity and negative predictive value for LNM for the three factors when combined was 96.1 and 95% respectively. This means that 5% of the patients who did not have the risk factors mentioned above developed LNM. Conclusion: This model used the combination of three factors (low-graded histological differentiation, distinct tumor boundary, small tumor size) and they proved to be useful in predicting LNM in ICC with clinically lymph node negative cases. In patients with these criteria, lymph node dissection or lymph node irradiation may be omitted and such cases may also be good candidates for stereotactic body radiotherapy (SBRT)