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.
Highlights • Regional and network functional changes could be seen in the early stage of SCI. • Functional changes were associated with clinical symptom severity in SCI patients. • Functional ...reorganization may reflect a compensatory role in the recovery of SCI.
The objectives of this study were to propose a clinical prognostic scoring system applicable for intrahepatic cholangiocarcinoma (ICC) and to evaluate the prognostic validity of the American Joint ...Committee on Cancer (AJCC) 7th edition staging system.
Retrospective univariate and multivariate survival analyses were conducted for 344 patients with ICC who underwent hepatectomy. A simple clinical prognostic scoring system (Fudan score) was developed based on the independent predictors. The prognostic validity was assessed in 74 patients with unresected tumors and compared with the AJCC 6th and 7th edition systems.
In the training set, serum alkaline phosphatase level, carbohydrate antigen 19-9 level, tumor boundary type, tumor size, and number of intrahepatic tumors were independent predictive factors of survival in ICC and were incorporated into the Fudan score. Three hundred forty-four patients were categorized into four subsets with 5-year overall survival rates of 48.6%, 25.6%, 10.3%, and 0.0% for low-, intermediate-, high-, and extremely high-risk groups, respectively. The discriminative ability of the Fudan score was better than that of the AJCC staging system and well applied in the unresected patient set.
A Fudan score based on clinical factors may provide a relatively accurate prognostic prediction for ICC patients regardless of resection status.
We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/silicon pyramid arrays structure (GO/Ag/PSi). The SERS behaviors are discussed and ...compared by the detection of R6G. Based on the contrast experiments with PSi, GO/PSi, Ag/PSi and GO/AgA/PSi as SERS substrate, the perfect bio-compatibility, good homogeneity and chemical stability were confirmed. We also calculated the electric field distributions using Finite-difference time-domain (FDTD) analysis to further understand the GO/Ag/PSi structure as a perfect SERS platform. These experimental and theoretical results imply that the GO/Ag/PSi with regular pyramids array is expected to be an effective substrate for label-free sensitive SERS detections in areas of medicine, food safety and biotechnology.
Monolayer transition-metal dichalcogenides (TMDs) have the potential to become efficient optical-gain materials for low-energy-consumption nanolasers with the smallest gain media because of strong ...excitonic emission. However, until now TMD-based lasing has been realized only at low temperatures. Here we demonstrate for the first time a room-temperature laser operation in the infrared region from a monolayer of molybdenum ditelluride on a silicon photonic-crystal cavity. The observation is enabled by the unique combination of a TMD monolayer with an emission wavelength transparent to silicon, and a high-Q cavity of the silicon nanobeam. The laser is pumped by a continuous-wave excitation, with a threshold density of 6.6 W cm
. Its linewidth is as narrow as 0.202 nm with a corresponding Q of 5,603, the largest value reported for a TMD laser. This demonstration establishes TMDs as practical materials for integrated TMD-silicon nanolasers suitable for silicon-based nanophotonic applications in silicon-transparent wavelengths.
The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two ...types of plasma disruptive discharges have been investigated for similar equilibrium parameters: one with a distinct stage of a small central temperature collapse (Formula: see text 5-10%) around 1 millisecond before the thermal quench (TQ), while the other without. For both types, the TQ phase is preceded by a rotating 2/1 tearing mode, and it is the development of the cold bubble from the inner region of the 2/1 island O-point along with its inward convection that causes the massive energy loss. In addition, the micro-scale turbulence, including magnetic fluctuations and density fluctuations, increases before the small collapse, and more significantly towards the TQ. Also, temperature fluctuations measured by electron cyclotron emission imaging enhances dramatically at the reconnection site and expand into the island when approaching the small collapse and TQ, and the expansion is more significant close to the TQ. The observed turbulence enhancement near the X-point cannot be fully interpreted by the linear stability analysis by GENE. Evidences suggest that nonlinear effects, such as the reduction of local Formula: see text shear and turbulence spreading, may play an important role in governing turbulence enhancement and expansion. These results imply that the turbulence and its interaction with the island facilitate the stochasticity of the magnetic flux and formation of the cold bubble, and hence, the plasma disruption.
Parasitic wasps rely on olfaction to locate their hosts in complex chemical environments. Odorant receptors (ORs) function together with well‐conserved odorant coreceptors (ORcos) to determine the ...sensitivity and specificity of olfactory reception. Campoletis chlorideae (Hymenoptera: Ichneunmonidae) is a solitary larval endoparasitoid of the cotton bollworm, Helicoverpa armigera, and some other noctuid species. To understand the molecular basis of C. chlorideae’s olfactory reception, we sequenced the transcriptome of adult male and female heads (including antennae) and identified 211 OR transcripts, with 95 being putatively full length. The tissue expression profiles, as assessed by reverse‐transcription PCR, showed that seven ORs were expressed only or more highly in female antennae. Their functions were analysed using the Xenopu slaevis oocyte expression system and two‐electrode voltage‐clamp recordings. CchlOR62 was tuned to cis‐jasmone, which was attractive to female C. chlorideae adults and H. armigera larvae in the subsequent behavioural assays. Further bioassays using caged plants showed that the parasitism rate of H. armigera larvae by C. chlorideae on cis‐jasmone‐treated tobacco plants was higher than on the control plants. Thus, cis‐jasmone appears to be an important infochemical involved in the interactions of plants, H. armigera and C. chlorideae, and CchlOR62 mediates the attractiveness of cis‐jasmone to C. chlorideae.
Al-Zn-Cu-Mg alloys (e.g., AA7075) have been widely used to form structural components in aerospace and other industries. For Al-Zn-Cu-Mg alloys, although dynamic recovery was dominant in hot ...deformation, dynamic recrystallization also occurred frequently, such as continuous dynamic recrystallization (CDRX), for which various mechanisms were found, e.g. subgrain boundary migration, subgrain coalescence, and subgrain rotation. However for the as-extruded AA7075 alloy subjected to hot compression, the mechanisms of CDRX process and model for it are lacking. In this paper by conducting thermal simulation compression tests combined with electron back scattered diffraction (EBSD) experiments, a continuous dynamic recrystallization (CDRX) process during the hot deformation of the as-extruded Al-Zn-Cu-Mg alloy (AA7075) is revealed based on the analysis on deformation behavior and characteristics of the recrystallized microstructures. It was found that subgrains, which were formed through dynamic recovery (DRV), rotated by absorbing dislocations into its boundaries, and resulted in the formation of the recrystallized grains. Then based on the explored CDRX mechanism, the dislocation density, subgrain boundary area, recrystallized grain boundary area, high angle grain boundary area and subgrain boundary misorientation were determined as internal-state-variables, and a continuous dynamic recrystallization model for AA7075 alloy was developed. In the established model, the process of subgrain rotation was described by introducing subgrain boundary stored energy, which related to dislocation density, subgrain size and misorientation. Finally, the continuous dynamic recrystallization model was combined with a constitutive model for the unified prediction of the flow stress and the microstructure evolution during the hot deformation of AA7075. Predictions of the model are in good agreement with the experimental ones.
•CDRX occurred during hot compression of as-extruded Al-Zn-Cu-Mg alloy (AA7075).•Subgrain formed in DRV and rotated by absorbing dislocations to result in HABs and CDRX.•CDRX was modeled based on ISV and combined with constitutive model for unified prediction.•Subgrain rotation was modeled by introducing subgrain stored energy.
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