Generalized Hofstadter model on a cubic optical lattice: From nodal bands to the three-dimensional quantum Hall effect

We propose that a tunable generalized three-dimensional Hofstadter Hamiltonian can be realized by engineering the Raman-assisted hopping of ultracold atoms in a cubic optical lattice. The Hamiltonian describes a periodic lattice system under artificial magnetic fluxes in three dimensions. For certain hopping configurations, the bulk bands can have Weyl points and nodal loops, respectively, allowing the study of both the two nodal semimetal states within this system. Furthermore, we illustrate that with proper rational fluxes and hopping parameters, the system can exhibit the three-dimensional quantum Hall effect when the Fermi level lies in the band gaps, which is topologically characterized by one or two nonzero Chern numbers. Our proposed optical-lattice system provides a promising platform for exploring various exotic topological phases in three dimensions.Comment: 10 pages, 5 figure

Reconstructing solar wind inhomogeneous structures from stereoscopic observations in white-light: Small transients along the Sun-Earth line

The Heliospheric Imagers (HI) on board the two spacecraft of the Solar Terrestrial Relations Observatory (STEREO) provided white-light images of transients in the solar wind from dual perspectives from 2007 to 2014. In this paper, we develop a new method to identify and locate the transients automatically from simultaneous images from the two inner telescopes, known as HI-1, based on a correlation analysis. Correlation coefficient (cc) maps along the Sun-Earth line are constructed for the period from 1 Jan 2010 to 28 Feb 2011. From the maps, transients propagating along the Sun-Earth line are identified, and a 27-day periodic pattern is revealed, especially for small-scale transients. Such a periodicity in the transient pattern is consistent with the rotation of the Sun's global magnetic structure and the periodic crossing of the streamer structures and slow solar wind across the Sun-Earth line, and this substantiates the reliability of our method and the high degree of association between the small-scale transients of the slow solar wind and the coronal streamers. Besides, it is suggested by the cc map that small-scale transients along the Sun-Earth line are more frequent than large-scale transients by a factor of at least 2, and that they quickly diffused into background solar wind within about 40 Rs in terms of the signal-to-noise ratio of white-light emissions. The method provides a new tool to reconstruct inhomogeneous structures in the heliosphere from multiple perspectives.Comment: 24 pages, 9 figures, to be published on Journal of Geophysical Research - Space Physic

Majorana Fermions on Zigzag Edge of Monolayer Transition Metal Dichalcogenides

Majorana fermions, quantum particles with non-Abelian exchange statistics, are not only of fundamental importance, but also building blocks for fault-tolerant quantum computation. Although certain experimental breakthroughs for observing Majorana fermions have been made recently, their conclusive dection is still challenging due to the lack of proper material properties of the underlined experimental systems. Here we propose a new platform for Majorana fermions based on edge states of certain non-topological two-dimensional semiconductors with strong spin-orbit coupling, such as monolayer group-VI transition metal dichalcogenides (TMD). Using first-principles calculations and tight-binding modeling, we show that zigzag edges of monolayer TMD can host well isolated single edge band with strong spin-orbit coupling energy. Combining with proximity induced s-wave superconductivity and in-plane magnetic fields, the zigzag edge supports robust topological Majorana bound states at the edge ends, although the two-dimensional bulk itself is non-topological. Our findings points to a controllable and integrable platform for searching and manipulating Majorana fermions.Comment: 12 pages, 7 figure

Facile construction of nanofibrous ZnO photoelectrode for dye-sensitized solar cell applications

A facile method to prepare nanofibrous ZnO photoelectrodes with tunable thicknesses by electrospinning is reported. A “self-relaxation layer” is formed spontaneously between ZnO nanofibers and fluorine-doped SnO2 FTO substrate, which facilitates the release of interfacial tensile stress during calcination, resulting in good adhesion of ZnO film to FTO substrate. Dye-sensitized solar cells DSSCs based on the nanofibrous ZnO photoelectrodes are fabricated and an energy conversion efficiency of 3.02% is achieved under irradiation of AM 1.5 simulated sunlight with a power density of 100 mW cm−2, which shows good promise of electrospun nanofibrous ZnO as the photoelectrode in DSSCs

Value of superb microvascular imaging ultrasonography in the diagnosis of carpal tunnel syndrome: Compared with color Doppler and power Doppler.

The aim of this study was to compare the value of superb microvascular imaging (SMI) in carpal tunnel syndrome (CTS) with that of color Doppler ultrasonography (CDUS) and power Doppler ultrasonography (PDUS).Fifty patients with symptomatic CTS and 25 healthy volunteers were enrolled. The cross-sectional area (CSA), CDUS score, PDUS score, and SMI score of the median nerve (MN) at the carpal tunnel were recorded. The value of different ultrasonography (US) diagnostic strategies was calculated.The blood flow display ratio in the MN of the healthy volunteers had no statistical difference between CDUS, PDUS, and SMI (20%, 32%, and 48%, respectively, P \u3e.05). The blood flow display ratio for SMI in patients was significantly higher than that of CDUS and PDUS (90%, 52%, and 60%, respectively,

Vaccines Developed for Cancer Immunotherapy

Vaccines have been successfully used for prophylaxis of infectious diseases for a long time and in the last decades have inspired researchers to make products with similar immunological mechanisms for cancer immunotherapy, which has been developed rapidly into clinical applications and has shown remarkable therapeutic efficacy, as exemplified by chimeric Ag receptor T cell (CAR-T cell) and immune checkpoint inhibitor-based therapies which can efficiently strengthen the body’s immune system to fight against cancer, but they are also expensive. Therefore, encouraged by recent success of cancer immunotherapy, scientists are actively developing the low-cost tumor Ag-based vaccines, which, however, usually exhibit weak immunostimulating effects and, therefore, are often formulated with nanoparticulate carriers to form a vaccine adjuvant-delivery system (VADS), which can not only enhance the efficacy but also mitigate the off-target toxicity associated with conventional anticancer vaccines. These nanoparticulate carrier-based VADSs have demonstrated multiple functions, such as targetedly triggering Ag-presenting cells, reeducating tumor-associated macrophages (TAM) to function as tumor suppressor agent, and eliciting robust cytotoxic T lymphocytes (CTLs) to kill tumor cells. This chapter introduces multifunctional VADS that have been engineered with nanoparticulate carriers, including polymeric-, lipid-, metallic-, and cell-based nanoparticles, and used as an alternative to the existent tools for cancer immunotherapy