Abstract
Topological superconductors (TSCs) are unconventional superconductors with bulk superconducting gap and in-gap Majorana states on the boundary that may be used as topological qubits for ...quantum computation. Despite their importance in both fundamental research and applications, natural TSCs are very rare. Here, combining state of the art synchrotron and laser-based angle-resolved photoemission spectroscopy, we investigated a stoichiometric transition metal dichalcogenide (TMD), 2M-WS
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with a superconducting transition temperature of 8.8 K (the highest among all TMDs in the natural form up to date) and observed distinctive topological surface states (TSSs). Furthermore, in the superconducting state, we found that the TSSs acquired a nodeless superconducting gap with similar magnitude as that of the bulk states. These discoveries not only evidence 2M-WS
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as an intrinsic TSC without the need of sensitive composition tuning or sophisticated heterostructures fabrication, but also provide an ideal platform for device applications thanks to its van der Waals layered structure.
The diffusion and coalescence of metal nanoparticles play important roles in many phenomena. Here, we offer a new integrated overview of the main factors that control the nanoparticle coalescence ...process. Three factors are considered in our description of the coalescence process: nanoparticle diffusion across the surface, their physical and thermodynamic properties, and the mechanism of coalescence. We demonstrate that the liquidlike properties of the surface layers of the nanoparticles play an essential role in this process. We present experimental evidence for our opinion, based on the high-resolution electron microscopic analysis of several different types of nanoparticles.
Development of nanoelectronics requires two-dimensional (2D) systems with both direct-bandgap and tunable electronic properties as they act in response to the external electric field (E-field). Here, ...we present a detailed theoretical investigation to predict the effect of atomic structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide (BP). We demonstrate that the splitting of bands and bandgap of BP depends on the number of layers and the stacking order. The values for the bandgap show a monotonically decreasing relationship with increasing layer number. We also show that AB-stacking BP has a direct-bandgap, while ABA-stacking BP has an indirect-bandgap when the number of layers n > 2. In addition, for a bilayer and a trilayer, the bandgap increases (decreases) as the electric field increases along the positive direction of the external electric field (E-field) (negative direction). In the case of four-layer BP, the bandgap exhibits a nonlinearly decreasing behavior as the increase in the electric field is independent of the electric field direction. The tunable mechanism of the bandgap can be attributed to a giant Stark effect. Interestingly, the investigation also shows that a semiconductor-to-metal transition may occur for the four-layer case or more layers beyond the critical electric field. Our findings may inspire more efforts in fabricating new nanoelectronics devices based on few-layer BP.
The Heavy Ion Research Facility in Lanzhou (HIRFL) is a multi-disciplinary research facility that provides heavy ion beams for physical, biomedical and material sciences. It is a major academic ...facility of China and one of the world's important centers in nuclear physics and accelerators. The facility was built step by step at Institute of Modern Physics (IMP) over a half century. The first cyclotron was built with great assistance from the former Soviet Union in 1960s, and the newest linear accelerator was tested successfully in 2019. The HIRFL accelerator can provide beams from proton to Uranium with energies of hundreds MeV/u, and hence diverse fundamental sciences and applied researches were carried out at IMP. In this paper, an introduction of the HIRFL accelerator complex was presented. Details of the HIRFL components including ion sources, cyclotrons, synchrotrons, linac and experimental terminals were described. The current operation status and upgrade plans were reported.
Abstract
We present the discovery and timing results of four pulsars discovered in a pilot survey at intermediate Galactic latitudes with the Five-hundred Aperture Spherical Telescope (FAST). Among ...these pulsars, two belong to the category of millisecond pulsars (MSPs) with spin periods of less than 20 ms. The other two fall under the classification of “mildly recycled” pulsars, with massive white dwarfs as companions. Remarkably, this small survey, covering an area of 4.7 deg
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, led to the discovery of four recycled pulsars. Such success underscores the immense potential of future surveys at intermediate Galactic latitudes. In order to assess the potential yield of MSPs, we conducted population simulations and found that both FAST and Parkes new phased array feed surveys, focusing on intermediate Galactic latitudes, have the capacity to uncover several hundred new MSPs.
We have carried out the functionalization of multiwalled carbon nanotubes (MWCNTs) via π−π interaction with benzyl mercaptan. The presence of noncovalently bonded benzyl mercaptan was demonstrated by ...X-ray photoelectron spectroscopy, which revealed spectral changes indicating its π−π interaction with the CNTs. The subsequent bonding of the thiol groups to both evaporated and chemically reduced Pt nanoparticles was demonstrated by the formation of strong Pt−S bonds in the Pt 4f and S 2p spectra. High-resolution transmission electron microscopy was used to confirm the Pt nanoparticle distribution along the walls of the CNTs.
Blood-circulating microRNAs (miRNAs) have been reported to be used as potential biomarkers in various cancers. MiR-101 has been found to act as a tumor suppressor in many tumor types, but little is ...known for osteosarcoma. The purpose of this study was to investigate miR-101 expression in osteosarcoma patients and assess its correlation with clinical features and prognosis. Serum samples from 152 osteosarcoma patients and 70 healthy controls were detected using quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The data showed that miR-101 expression levels were remarkably underexpressed in serum samples from osteosarcoma patients compared to controls, and the post-treatment serum miR-101 expression was significantly higher than that in the pre-treatment expression. Low serum miR-101 expression was positively associated with advanced clinical stage and distant metastasis. Receiver operating characteristic (ROC) curve analysis showed that serum miR-101 could serve as a useful marker for osteosarcoma diagnosis, with a high sensitivity and specificity. Moreover, patients with high miR-101 expression had longer overall survival and recurrence free survival than those with low miR-101 expression. In addition, both univariate and multivariate analyses showed that serum miR-101 downregulation was associated with shorter overall survival and recurrence free survival. Our present results implicated serum miR-101 might be a useful biomarker for the clinical diagnosis and prognosis of osteosarcoma.
HIAF (High Intensity heavy ion Accelerator Facility), a new facility planned in China for heavy ion related researches, consists of two ion sources, a high intensity Heavy Ion Superconducting Linac ...(HISCL), a 45 Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage ring system. The key features of HIAF are unprecedented high pulse beam intensity and versatile operation mode. The HIAF project aims to expand nuclear and related researches into presently unreachable region and give scientists possibilities to conduct cutting-edge researches in these fields. The general description of the facility is given in this article with a focus on the accelerator design.
In this paper, a non-Paris-law-based, unified fatigue cohesive zone model (CZM) that can predict both fatigue crack initiation and propagation in composites with or without starter cracks or stress ...concentrators has been formulated and validated. The fatigue CZM incorporates normal and shear S–N curves for pre-initiation strength degradation, and simple power-laws for post-initiation fatigue damage accumulation with damage rate computed directly from the in situ cohesive traction–separation history. A unique procedure to determine the in situ loading profiles and an efficient cycle jump strategy have also been developed. It has been demonstrated, through direct comparisons against experimental results, that the proposed fatigue CZM can successfully predict the crack initiation and the ensuing propagation in pre-cracked as well as in crack-free specimens. Furthermore, as the cracks become sufficiently long for linear elastic fracture mechanics (LEFM) conditions to be dominant, the model can correctly predict the Paris laws under pure or mixed mode fracture conditions.
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