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Many proposals in exploring topological quantum computation are based on superconducting quantum devices constructed on materials with strong spin-orbit coupling (SOC). For these devices, a full control on both the magnitude and the spatial distribution of the supercurrent would be highly demanded, but has been elusive up to now. We constructed proximity-type Josephson junction on nanoplates of Bi2O2Se, a new emerging semiconductor with strong SOC. Through electrical gating, we show that the supercurrent can be fully turned ON and OFF, and its real-space pathways can be configured either through the bulk or along the edges. Our work demonstrates Bi2O2Se as a promising platform for constructing multifunctional hybrid superconducting devices as well as for searching for topological superconductivity.

Andreev bound states (ABSs), as a close resemblance and a prototype of Majorana bound states, attracted particular interest in semiconductor-superconductor hybrids. So far, ABSs were explored as an equilibrium behavior employing tunneling spectroscopy. Under nonequilibrium, theorists did predict that the local density of states (DOS) of the ABSs split and broaden. We investigated an InAsSb quantum dot coupled to two superconductors to explore the nonequilibrium dynamics of ABSs and their interplay with Kondo effect. Through tunneling spectroscopy, we demonstrated a full picture of the nonequilibrium dynamic splitting and broadening of ABSs, which interplays with the nonequilibrium Kondo DOS. Since the observed features might mimic those in the normal superconductor-topological superconductor or Majorana junctions, our discovery could provide a relevant comparison to benchmark the Majorana signal in future experiments.

ObjectiveResearch on the antidepressant effects of sleep deprivation (SD) is lagging and has not produced completely uniform results in humans and animals. The present study aimed to reassess the effect of SD on patients and animals by meta-analysis based on updated research.MethodsWe searched PubMed, Embase and Cochrane Library for articles since the first relevant literature published up to June 10th, 2019. Data on sample characteristics, features of SD, and tests for depression were extracted.ResultsFourteen articles were included, eight on humans and six on animals. We found that when the duration of SD in patients was 7–14 days, it reflected antidepression [-1.52 (−2.07, −0.97); I2=19.6%]. In animals, the results of sucrose consumption experiments showed that SD has depressogenic effects [-1.06 (−1.63, −0.49); I2=81.1%], while the results of forced swimming experiments showed that SD treated depression [-1.17 (−2.19, −0.16); I2=80.1%], regardless of the duration of sleep deprivation.ConclusionSD can be an effective antidepressant measure when the duration is 7–14 days in patients. In animal studies, SD has shown more antidepressant effects when measured by forced swimming experiments, whereas using sucrose consumption tests had the effect of worsening depression.

We report on the successful synthesis and low-temperature electron transport investigations of a new form of material---$\mathrm{B}{\mathrm{i}}_{2}{\mathrm{O}}_{2}\mathrm{Se}$ semiconducting nanowires. Gate-tunable 0- and $\ensuremath{\pi}\text{\ensuremath{-}}h/e\phantom{\rule{4pt}{0ex}}(h$ is the Planck constant and $e$ the elementary charge) periodic resistance oscillations in longitudinal magnetic field were observed unexpectedly, demonstrating novel quasiballistic, phase-coherent surface states in $\mathrm{B}{\mathrm{i}}_{2}{\mathrm{O}}_{2}\mathrm{Se}$ nanowires. By reaching a very good agreement between the calculated density of states and the experimental data, we clarified the mechanism to be the one-dimensional subbands formed along the circumference of the nanowire rather than the usually considered Aharonov-Bohm interference. A qualitative physical picture based on downward band bending associated with the complex band structure is proposed to describe the formation of the surface states.

Gastric ulcers (GUs) are common pathologies that affect many people around the world. Excessive alcohol consumption is one of the main causes of GUs; however, there are still lack of effective drugs for the prevention or therapy of GUs. In this study, we evaluated the protective effects and possible mechanisms of kaempferol (KAE) against acute ethanol-induced lesions to the gastric mucosa in mice. Fasted mice were orally given vehicle (0.9% saline), omeprazole (20 mg/kg), or KAE (40, 80, or 160 mg/kg) for 1 h in different experimental sets prior to the establishment of the GU model by challenge with absolute ethanol (10 ml/kg). Animals were euthanized 1 h after ethanol intake, and their plasma and stomach tissues were subject to further examination. Macroscopic and microscopic lesions, and immunological and biochemical parameters were observed. The effects of inflammation were investigated using the following indicators: tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, myeloperoxidase (MPO), and nitric oxide (NO). Results showed that KAE significantly decreased the ulcer index, increased the preventive index, completely protected the mucosa from lesions, and preserved gastric mucosal glycoprotein. KAE decreased MPO activity and pro-inflammatory cytokine (TNF-α, and IL-1β) levels, and improved NO levels. The gastroprotective activity of KAE might be attributed to the preservation of gastric mucous glycoproteins levels, thus by inhibiting neutrophil accumulation and MPO activity, adjusting the levels of pro-inflammatory cytokines, and improving NO production.

We carried out a phase-sensitive experiment on Josephson trijunctions constructed on the surface of three-dimensional topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$. Through local flux contol and contact resistance measurement, we observed that the minigap at the ends of the trijunctions approaches zero linearly with varying phase difference and closes completely at $\ensuremath{\pi}$ phase difference. The minigap at the center of the trijunction is protected to close over extended regions in phase space. These results agree with the theory by Fu and Kane [Phys. Rev. Lett. 100, 096407 (2008)].

Twisting two layers into a magic angle (MA) of ~1.1{\deg} is found essential to create low energy flat bands and the resulting correlated insulating, superconducting, and magnetic phases in twisted bilayer graphene (TBG). While most of previous works focus on revealing these emergent states in MA-TBG, a study of the twist angle dependence, which helps to map an evolution of these phases, is yet less explored. Here, we report a magneto-transport study on one non-magic angle TBG device, whose twist angle {\theta} changes from 1.25{\deg} at one end to 1.43{\deg} at the other. For {\theta}=1.25{\deg}, we observe an emergence of topological insulating states at hole side with a sequence of Chern number |C|=4-|v|, where v is the number of electrons (holes) in moir\'e unite cell. When {\theta}>1.25{\deg}, the Chern insulator from flat band disappears and evolves into fractal Hofstadter butterfly quantum Hall insulator where magnetic flux in one moir\'e unite cell matters. Our observations will stimulate further theoretical and experimental investigations on the relationship between electron interactions and non-trivial band topology., Comment: accepted in CPL express letter

The discovery of a new type-II Dirac semimetal in Ir1-x Ptx Te2 with optimized band structure is described. Pt dopants protect the crystal structure holding the Dirac cones and tune the Fermi level close to the Dirac point. The type-II Dirac dispersion in Ir1-x Ptx Te2 is confirmed by angle-resolved photoemission spectroscopy and first-principles calculations. Superconductivity is also observed and persists when the Fermi level aligns with the Dirac points. Ir1-x Ptx Te2 is an ideal platform for further studies on the exotic properties and potential applications of type-II DSMs, and opens up a new route for the investigation of the possible topological superconductivity and Majorana physics.