Search

In a molecule formed by two atoms, energy difference between bonding and antibonding orbitals depends on distance between the two atoms. However, exploring molecular orbitals of two natural atoms with tunable distance has remained an outstanding experimental challenge. Graphene quantum dots can be viewed as relativistic artificial atoms, thus offering a unique platform to study molecular physics. Here, through scanning tunneling microscope, we create and directly visualize the formation process of relativistic artificial molecules based on two coupled graphene quantum dots with tunable distance. Our study indicates that energy difference between the bonding and antibonding orbitals of the lowest quasibound state increases linearly with inverse distance between the two graphene quantum dots due to the relativistic nature of the artificial molecule. For quasibound states with higher orbital momenta, the coupling between these states leads to half-energy spacing of the confined states because the length of the molecular-like orbit is approximately twice that of the atomic-like orbit. Evolution from ring-like whispering-gallery modes in the artificial atoms to figure-eight orbitals in the artificial molecules is directly imaged. The ability to resolve the coupling and orbitals of the relativistic artificial molecule at the nanoscale level yields insights into the behavior of quantum-relativistic matter., (© 2024. The Author(s).)

In the last decade, chirality-induced spin selectivity (CISS) has undergone intensive study. However, there remain several critical issues, such as the microscopic mechanism of CISS, especially transverse CISS where electrons are injected perpendicular to the helix axis of chiral molecules, quantitative agreement between experiments and theory, and at which level the molecular handedness is key to the CISS. Here, we address these issues by performing a combined experimental and theoretical study on conducting polyaniline helical nanofibers which are synthesized in the absence of any chiral species. Large spin polarization is measured in both left- and right-handed nanofibers for electrons injected perpendicular to their helix axis, and it will be reversed by switching the nanofiber handedness. We first develop a theoretical model to study this transverse CISS and quantitatively explain the experiment. Our results reveal that our theory provides a unifying scheme to interpret a number of CISS experiments, quantitative agreement between experiments and numerical calculations can be achieved by weak spin-orbit coupling, and the supramolecular handedness is sufficient for spin selectivity without any chiral species.

Topological systems hosting gapless boundary states have attracted huge attention as promising components for next-generation information processing, attributed to their capacity for dissipationless electronics. Nevertheless, recent theoretical and experimental inquiries have revealed the emergence of energy dissipation in precisely quantized electrical transport. Here, we present a criterion for the realization of truly no-dissipation design, characterized as N in = N tunl + N bs , where N in , N tunl , and N bs represent the number of modes participating in injecting, tunneling, and backscattering processes, respectively. The key lies in matching the number of injecting, tunneling, and backscattering modes, ensuring the equilibrium among all engaged modes inside the device. Among all the topological materials, we advocate for the indispensability of Chern insulators exhibiting higher Chern numbers to achieve functional devices and uphold the no-dissipation rule simultaneously. Furthermore, we design the topological current divider and collector, evading dissipation upon fulfilling the established criterion. Our work paves the path for developing the prospective topotronics.

We propose a universal spin superconducting diode effect (SDE) induced by spin-orbit coupling (SOC) in systems with spin-triplet correlations, where the critical spin supercurrents in opposite directions are unequal. By analysis from both the Ginzburg-Landau theory and energy band analysis, we show that the spin-↑↑ and spin-↓↓ Cooper pairs possess opposite phase gradients and opposite momenta from the SOC, which leads to the spin SDE. Two superconductors with SOC, a p-wave superconductor as a toy model and a practical superconducting nanowire, are numerically studied and they both exhibit spin SDE. In addition, our theory also provides a unified picture for both spin and charge SDEs.

Energy dissipation is of fundamental interest and crucial importance in quantum systems. However, whether energy dissipation can emerge without backscattering inside topological systems remains a question. As a hallmark, we propose a microscopic picture that illustrates energy dissipation in the quantum Hall (QH) plateau regime of graphene. Despite the quantization of Hall, longitudinal, and two-probe resistances (dubbed as the quantum limit), we find that the energy dissipation emerges in the form of Joule heat. It is demonstrated that the non-equilibrium energy distribution of carriers plays much more essential roles than the resistance on energy dissipation. Eventually, we suggest probing the phenomenon by measuring local temperature increases in experiments and reconsidering the dissipation typically ignored in realistic topological circuits., (Copyright © 2023. Published by Elsevier B.V.)

Phase singularities are phase-indeterminate points where wave amplitudes are zero, which manifest as phase vertices or wavefront dislocations. In the realm of optical and electron beams, the phase singularity has been extensively explored, demonstrating a profound connection to orbital angular momentum. Direct local imaging of the impact of orbital angular momentum on phase singularities at the nanoscale, however, remains challenging. Here, we study the role of orbital angular momentum in phase singularities in graphene, particularly at the atomic level, through scanning tunneling microscopy and spectroscopy. Our experiments demonstrate that the scatterings between different orbital angular momentum states, which are induced by local rotational symmetry-breaking potentials, can generate additional phase singularities, and result in robust single-wavefront dislocations in real space. Our results pave the way for exploring the effects of orbital degree of freedom on quantum phases in quasiparticle interference processes., (© 2024. The Author(s).)

Quantum spin Hall effect is characterized by topologically protected helical edge states. Here we study the thermal dissipation of helical edge states by considering two types of dissipation sources. The results show that the helical edge states are dissipationless for normal dissipation sources with or without Rashba spin-orbit coupling in the system, but they are dissipative for spin dissipation sources. Further studies on the energy distribution show that electrons with spin-up and spin-down are both in their own equilibrium without dissipation sources. Spin dissipation sources can couple the two subsystems together to induce voltage drop and non-equilibrium distribution, leading to thermal dissipation, while normal dissipation sources cannot. With the increase of thermal dissipation, the subsystems of electrons with spin-up and spin-down evolve from non-equilibrium finally to mutual equilibrium. In addition, the effects of disorder on thermal dissipation are also discussed. Our work provides clues to reduce thermal dissipation in the quantum spin Hall systems., (© 2023 IOP Publishing Ltd.)

Recent experiments have revealed multiple borophene phases of distinct lattice structures, suggesting that the unit cells of ν 1/6 and ν 1/5 boron sheets, namely α and β chains, serve as building blocks to assemble into novel borophene phases. Motivated by these experiments, we present a theoretical study of electron transport along two-terminal quasiperiodic borophene nanoribbons (BNRs), with the arrangement of the α and β chains following the generalized Fibonacci sequence. Our results indicate that the energy spectrum of these quasiperiodic BNRs is multifractal and characterized by numerous transmission peaks. In contrast to the Fibonacci model that all the electronic states should be critical, both delocalized and critical states appear in the quasiperiodic BNRs, where the averaged resistance saturates at the inverse of one conductance quantum for the delocalized states in the large length limit and contrarily exhibits a power-law dependence on the nanoribbon length for the critical states. Besides, the self-similarity is observed from the transmission spectrum, where the conductance curves overlap at different energy regions of two quasiperiodic BNRs of different Fibonacci indices and the resistance curves are analogous to each other at different energy scales of a single quasiperiodic BNR. These results complement previous studies on quasiperiodic systems where the multifractal energy spectrum and the self-similarity are observed by generating quasiperiodic potential energies, suggesting that borophene may provide an intriguing platform for understanding the structure-property relationships and exploring the physical properties of quasiperiodic systems.

In relativistic physics, both atomic collapse in a heavy nucleus and Hawking radiation in a black hole are predicted to occur through the Klein tunneling process that couples particles and antiparticles. Recently, atomic collapse states (ACSs) were explicitly realized in graphene because of its relativistic Dirac excitation with a large "fine structure constant." However, the essential role of the Klein tunneling in the ACSs remains elusive in experiment. Here we systematically study the quasibound states in elliptical graphene quantum dots (GQDs) and two coupled circular GQDs. Bonding and antibonding molecular collapse states formed by two coupled ACSs are observed in both systems. Our experiments supported by theoretical calculations indicate that the antibonding state of the ACSs will change into a Klein-tunneling-induced quasibound state revealing deep connection between the ACSs and the Klein tunneling.

Recently, a half-quantized Hall conductance (HQHC) plateau was experimentally observed in a semimagnetic topological insulator heterostructure. However, the heterostructure was metallic with a nonzero longitudinal conductance, which contradicts the common belief that quantized Hall conductance is usually observed in insulators. In this work, we systematically study the surface transport of a semimagnetic topological insulator with both gapped and gapless Dirac surfaces in the presence of dephasing process. In particular, we reveal that the HQHC is directly related to the half-quantized chiral current along the edge of a strongly dephasing metal. The Hall conductance keeps a half-quantized value for large dephasing strengths, while the longitudinal conductance varies with Fermi energies and dephasing strengths. Furthermore, we evaluate both the conductance and resistance as a function of the temperature, which is consistent with the experimental results. Our results not only provide the microscopic transport mechanism of the HQHC, but also are instructive for the probe of the HQHC in future experiments.

Introducing quantum confinement has uncovered a rich set of interesting quantum phenomena and allows one to directly probe the physics of confined (quasi-)particles. In most experiments, however, an electrostatic potential is the only available method to generate quantum dots in a continuous system to confine (quasi-)particles. Here we demonstrate experimentally that inhomogeneous pseudomagnetic fields in strained graphene can introduce exotic quantum confinement of massless Dirac fermions. The pseudomagnetic fields have opposite directions in the two distinct valleys of graphene. By adding and tuning real magnetic fields, the total effective magnetic fields in the two valleys are imbalanced. By that we realized valley-contrasting spatial confinement, which lifts the valley degeneracy and results in field-tunable valley-polarized confined states in graphene. Our results provide a new avenue to manipulate the valley degree of freedom.

The Berry phase plays an important role in determining many physical properties of quantum systems. However, tuning the energy spectrum of a quantum system via Berry phase is comparatively rare because the Berry phase is usually a fixed constant. Here, we report the realization of an unusual valley-polarized energy spectra via continuously tunable Berry phases in Bernal-stacked bilayer graphene quantum dots. In our experiment, the Berry phase of electron orbital states is continuously tuned from about π to 2π by perpendicular magnetic fields. When the Berry phase equals π or 2π, the electron states in the two inequivalent valleys are energetically degenerate. By altering the Berry phase to noninteger multiples of π, large and continuously tunable valley-polarized energy spectra are realized. Our result reveals the Berry phase's essential role in valleytronics and the observed valley splitting, on the order of 10 meV at a magnetic field of 1 T, is about 100 times larger than Zeeman splitting for spin, shedding light on graphene-based valleytronics.

Background and Objective: This pilot study aimed to identify potential blood DNA methylation (BDM) biomarker genes for the diagnosis of liver fibrosis in non-alcoholic fatty liver disease (NAFLD)., Methods: We included a total of 16 NAFLD patients with significant (SLF, liver fibrosis stage ≥ 2) and 16 patients with non-significant liver fibrosis (NSLF, fibrosis stages 0-1). The association between BDM and liver fibrosis was analyzed. Genes were selected based on a stepwise-filtering with CpG islands containing significant differentially methylated probes., Results: The two groups of patients were distinguishable through both t-distributed stochastic neighbor embedding (t-SNE) analysis and unsupervised hierarchical clustering analysis based on their BDM status. BDM levels were significantly higher in the NSLF group than in the SLF group. The methylation levels in the island and shelf regions were also significantly higher in the NSLF group, as well as the methylation levels in the first exon, 3'-untranslated region, body, ExonBnd, non-intergenic region, transcription start site (TSS)1500, and TSS200 regions (all p < 0.05). BDM status was associated with greater histological liver fibrosis, but not with age, sex, or other histological features of NAFLD ( p < 0.05). The methylation levels of the hypomethylated CpG island region of CISTR , IFT140 , and RGS14 genes were increased in the NSLF group compared to the SLF group (all p < 0.05)., Conclusion: BDM may stratify NAFLD patients with significant and non-significant liver fibrosis. The CISTR , IFT140 , and RGS14 genes are potential novel candidate BDM biomarkers for liver fibrosis and these pilot data suggest further work on BDM biomarkers is warranted., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sun, Tang, Wang, Zhu, Li, Ma, Huang, Hong, Li, Byrne, Targher, Liu, Lu, Ding and Zheng.)

The relativistic massless charge carriers with a Fermi velocity of about c/300 in graphene enable us to realize two distinct types of resonances (here, c is the speed of light in vacuum). One is the electron whispering-gallery mode in graphene quantum dots arising from the Klein tunneling of the massless Dirac fermions. The other is the atomic collapse state, which has never been observed in experiment with real atoms due to the difficulty of producing heavy nuclei with charge Z > 170; however, they can be realized near a Coulomb impurity in graphene with a charge Z ≥ 1 because of the "small" velocity of the Dirac excitations. Here we demonstrate that both the electron whispering-gallery modes and atomic collapse states coexist in graphene/WSe 2 heterostructure quantum dots due to the Coulomb-like potential near their edges. By applying a perpendicular magnetic field, we explore the evolution from the atomic collapse states to unusual Landau levels in the collapse regime., (© 2022. The Author(s).)

Fundamental symmetry breaking and relativistic spin-orbit coupling give rise to fascinating phenomena in quantum materials. Of particular interest are the interfaces between ferromagnets and common s-wave superconductors, where the emergent spin-orbit fields support elusive spin-triplet superconductivity, crucial for superconducting spintronics and topologically-protected Majorana bound states. Here, we report the observation of large magnetoresistances at the interface between a quasi-two-dimensional van der Waals ferromagnet Fe 0.29 TaS 2 and a conventional s-wave superconductor NbN, which provides the possible experimental evidence for the spin-triplet Andreev reflection and induced spin-triplet superconductivity at ferromagnet/superconductor interface arising from Rashba spin-orbit coupling. The temperature, voltage, and interfacial barrier dependences of the magnetoresistance further support the induced spin-triplet superconductivity and spin-triplet Andreev reflection. This discovery, together with the impressive advances in two-dimensional van der Waals ferromagnets, opens an important opportunity to design and probe superconducting interfaces with exotic properties., (© 2021. The Author(s).)

Spin-dependent charge transmission or the so-called chirality-induced spin selectivity (CISS) effect was demonstrated in self-assembled chiral coordinated monolayers. Distinct from the previous CISS phenomenon observed mainly on pure biomolecules, here we expanded this effect to the coordinated complex of chiral biomolecules and metal cations, specifically, cysteine-Cu 2+ -alanine (Cys/Cu/Ala), in which the complex itself was redox-active. However, the coordinated self-assembled monolayers of cysteine-Cu 2+ -cysteine did not show any spin-dependent effect. In addition, this phenomenon was explained by developing a theoretical model with spin-orbit coupling. The alanine molecules contributed to multiple transport pathways, leading to experimentally observable spin polarization. Finally, this CISS effect in Cys/Cu/Ala complex was demonstrated to amplify the sensing signal. The enantioselective discrimination efficiency could be improved by controlling the orientation of the external magnetic field.

Background and Aim: Circulating levels of interleukin (IL)-6, a well-known inflammatory cytokine, are often elevated in coronavirus disease-2019 (COVID-19). Elevated IL-6 levels are also observed in patients with metabolic dysfunction-associated fatty liver disease (MAFLD). Our study aimed to describe the association between circulating IL-6 levels and MAFLD at hospital admission with risk of severe COVID-19., Methods: A total of 167 patients with laboratory-confirmed COVID-19 from three Chinese hospitals were enrolled. Circulating levels of IL-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ were measured at admission. All patients were screened for fatty liver by computed tomography. Forty-six patients were diagnosed as MAFLD., Results: Patients with MAFLD (n = 46) had higher serum IL-6 levels (median 7.1 [interquartile range, 4.3-20.0] vs. 4.8 [2.6-11.6] pg/mL, p = 0.030) compared to their counterparts without MAFLD (n = 121). After adjustment for age and sex, patients with MAFLD had a ~2.6-fold higher risk of having severe COVID-19 than those without MAFLD. After adjustment for age, sex and metabolic co-morbidities, increased serum IL-6 levels remained associated with higher risk of severe COVID-19, especially among infected patients with MAFLD (adjusted-odds ratio 1.14, 95% CI 1.05-1.23; p = 0.002). There was a significant interaction effect between serum IL-6 levels and MAFLD for risk of severe COVID-19 ( p for interaction = 0.008)., Conclusions: Patients with MAFLD and elevated serum IL-6 levels at admission are at higher risk for severe illness from COVID-19., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Gao, Zheng, Yan, Sun, Pan, Wang, Chen, Targher, Byrne, George and Zheng.)

Background and Aim: Coronavirus disease 2019 (COVID-19) has attracted increasing worldwide attention. While diabetes is known to aggravate COVID-19 severity, it is not known whether nondiabetic patients with metabolic dysfunction are also more prone to more severe disease. The association of metabolic associated fatty liver disease (MAFLD) with COVID-19 severity in nondiabetic patients was investigated here., Methods: The study cohort comprised 65 patients with (i.e. cases) and 65 patients without MAFLD (i.e. controls). Each case was randomly matched with one control by sex (1:1) and age (±5 years). The association between the presence of MAFLD (as exposure) and COVID-19 severity (as the outcome) was assessed by binary logistic regression analysis., Results: In nondiabetic patients with COVID-19, the presence of MAFLD was associated with a four-fold increased risk of severe COVID-19; the risk increased with increasing numbers of metabolic risk factors. The association with COVID-19 severity persisted after adjusting for age, sex, and coexisting morbid conditions., Conclusion: Health-care professionals caring for nondiabetic patients with COVID-19 should be cognizant of the increased likelihood of severe COVID-19 in patients with MAFLD., (© 2020 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

A pandemic of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection broke out all over the world; however, epidemiological data and viral shedding in pediatric patients are limited. We conducted a retrospective, multicenter study, and followed-up with all children from the families with SARS-CoV-2 infected members in Zhejiang Province, China. All infections were confirmed by testing the SARS-CoV-2 RNA with real-time reverse transcription PCR method, and epidemiological data between children and adults in the same families were compared. Effect of antiviral therapy was evaluated observationally and fecal-viral excretion times among groups with different antiviral regiments were compared with Kaplan-Meier plot. By 29 February 2020, 1298 cases from 883 families were confirmed with SARS-CoV-2 infection and 314 of which were families with children. Incidence of infection in child close contacts was significantly lower than that in adult contacts (13.2% vs 21.2%). The mean age of 43 pediatric cases was 8.2 years and mean incubation period was 9.1 days. Forty (93.0%) were family clustering. Thirty-three children had coronavirus disease 2019 (20 pneumonia) with mild symptoms and 10 were asymptomatic. Fecal SARS-CoV-2 RNA detection was positive in 91.4% (32/35) cases and some children had viral excretion time over 70 days. Viral clearance time was not different among the groups treated with different antiviral regiments. No subsequent infection was observed in family contacts of fecal-viral-excreting children. Children have lower susceptibility of SARS-CoV-2 infection, longer incubation, and fecal-viral excretion time. Positive results of fecal SARS-CoV-2 RNA detection were not used as indication for hospitalization or quarantine., (© 2020 Wiley Periodicals LLC.)

The Corona Virus Disease 2019 (COVID-19) pandemic has attracted increasing worldwide attention. While metabolic-associated fatty liver disease (MAFLD) affects a quarter of world population, its impact on COVID-19 severity has not been characterized. We identified 55 MAFLD patients with COVID-19, who were 1:1 matched by age, sex and obesity status to non-aged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients without MAFLD. Our results demonstrate that in patients aged less than 60 years with COVID-19, MAFLD is associated with an approximately fourfold increase (adjusted odds ratio 4.07, 95% confidence interval 1.20-13.79, P = .02) in the probability for severe disease, after adjusting for confounders. Healthcare professionals caring for patients with COVID-19 need to be aware that there is a positive association between MAFLD and severe illness with COVID-19., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Radiological manifestations of coronavirus disease 2019 (COVID-19) featured ground-glass opacities (GGOs), especially in the early stage, which might create confusion in differential diagnosis with early lung cancer. We aimed to specify the radiological characteristics of COVID-19 and early lung cancer and to unveil the discrepancy between them., Methods: One hundred and fifty-seven COVID-19 patients and 374 early lung cancer patients from four hospitals in China were retrospectively enrolled. Epidemiological, clinical, radiological, and pathological characteristics were compared between the two groups using propensity score-matched (PSM) analysis., Results: COVID-19 patients had more distinct symptoms, tended to be younger (P<0.0001), male (P<0.0001), and had a higher body mass index (P=0.014). After 1:1 PSM, 121 matched pairs were identified. Regarding radiological characteristics, patients with a single lesion accounted for 17% in COVID-19 and 89% in lung cancer (P<0.0001). Most lesions were peripherally found in both groups. Lesions in COVID-19 involved more lobes (median 3.5 vs. 1; P<0.0001) and segments (median 6 vs. 1; P<0.0001) and tended to have multiple types (67%) with patchy form (54%). Early lung cancer was more likely to have a single type (92%) with oval form (66%). Also, COVID-19 and early lung cancer either had some distinctive features on computed tomography (CT) images., Conclusions: Both COVID-19 and early lung cancers showed GGOs, with similar but independent features. The imaging characteristics should be fully understood and combined with epidemiological history, pathogen detection, laboratory tests, short-term CT reexamination, and pathological results to aid differential diagnosis., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/tlcr-20-892). Dr. YJZ reports grants from National Natural Science Foundation of China, during the conduct of the study. Dr. HCL reports grants from National Natural Science Foundation of China, grants from Shanghai Municipal Commission of Health and Family Planning Outstanding Academic Leaders Training Program, grants from Shanghai Municipal Education Commission - Gaofeng Clinical Medicine Grant, during the conduct of the study. The other authors have no conflicts of interest to declare., (2020 Translational Lung Cancer Research. All rights reserved.)

Berry phase, the geometric phase accumulated over a closed loop in parameter space during an adiabatic cyclic evolution, has been demonstrated to play an important role in many quantum systems since its discovery. In gapped Bernal bilayer graphene, the Berry phase can be continuously tuned from zero to 2π, which offers a unique opportunity to explore the tunable Berry phase on physical phenomena. Here, we report experimental observation of Berry-phase-induced valley splitting and crossing in movable bilayer-graphene p-n junction resonators. In our experiment, the resonators are generated by combining the electric field of a scanning tunneling microscope tip with the gap of bilayer graphene. A perpendicular magnetic field changes the Berry phase of the confined bound states in the resonators from zero to 2π continuously and leads to the Berry phase difference for the two inequivalent valleys in the bilayer graphene. As a consequence, we observe giant valley splitting and unusual valley crossing of the lowest bound states. Our results indicate that the bilayer-graphene resonators can be used to manipulate the valley degree of freedom in valleytronics.

Objective: This study aimed to investigate the effect of long non-coding RNA (lncRNA) DLGAP1 antisense RNA 1 (DLGAP1-AS1) on vascular endothelial cell (VEC) injury via the phosphoinositide 3-kinase (PI3K)/Akt pathway in rat models of acute lower limb ischaemia-reperfusion (I/R)., Methods: Differentially expressed lncRNAs related to I/R were screened using the gene expression omnibus database. Acute lower limb I/R models were induced in male Wistar rats, in which the regulatory mechanisms of DLGAP1-AS1 silencing were analysed after the treatment of small interfering RNA (siRNA) against DLGAP1-AS1 or an inhibitor of the PI3K/Akt pathway. The relationship between DLGAP1-AS1 and the PI3K/Akt pathway was analysed. The levels of tumour necrosis factor (TNF)-α and vascular cell adhesion molecule-1 (VCAM-1), as well as malondialdehyde (MDA) concentration and creatine kinase (CK) activity, were measured. The number of circulating endothelial cells (CECs) and apoptosis of VECs were identified., Results: Microarray based analysis indicated that DLGAP1-AS1 was highly expressed in I/R, which was further confirmed by detection of expression in rat models of acute lower limb I/R. Notably, the treatment of siRNA against DLGAP1-AS1 led to the activation of the PI3K/Akt pathway. In response to siRNA against DLGAP1-AS1, the levels of TNF-α and VCAM-1 were decreased, and MDA concentration and CK activity was downregulated. Reduced CEC numbers and suppressed VEC apoptosis were also observed., Conclusion: DLGAP1-AS1 silencing could further suppress the oxidative stress, exert an anti-apoptosis effect, and reduce inflammatory reaction, whereby VEC injury is alleviated by activation of the PI3K/Akt pathway in rats with acute lower limb I/R., (Copyright © 2019 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.)

The spin Nernst effect describes a transverse spin current induced by the longitudinal thermal gradient in a system with the spin-orbit coupling. Here we study the spin Nernst effect in a mesoscopic four-terminal cross-bar Weyl semimetal device under a perpendicular magnetic field. Because the spin current is a tensor, it has three elements with the spin direction pointing to the x, y  and z directions when the spin current flows along the transverse lead. By using the tight-binding Hamiltonian combined with the nonequilibrium Green's function method, the three elements of the spin current in the transverse leads and the spin Nernst coefficients are obtained. The results show that the spin Nernst effect in the Weyl semimetal has an essential difference to the traditional Nernst effect: we found that the z direction spin current is zero without the magnetic field while it appears under the magnetic field, and the x and y  direction spin currents in the two transverse leads flow out or in together, in contrast to the traditional spin Nernst effect, in which the spin current is induced by the spin-orbit coupling and flows out from one lead and flows in on the other. We call it the anomalous spin Nernst effect. In addition, we show that the Weyl semimetals have inversion-type symmetry, mirror-reversal-type symmetry and electron-hole-type symmetry, which lead to the spin Nernst coefficients being either odd or even functions of the Fermi energy, the magnetic field and the transverse terminals. Moreover, the spin Nernst effect in the Weyl semimetals are strongly anisotropic and its coefficients are strongly dependent on both the direction of thermal gradient and the direction of the transverse lead connection. Three non-equivalent connection modes (x-z, z-x and x-y  modes) are studied in detail, and the spin Nernst coefficients for three different modes exhibit very different behaviors. These strongly anisotropic behaviors of the spin Nernst effect can be used as the characterization of magnetic Weyl semimetals.

An intriguing observation on the quantum anomalous Hall effect (QAHE) in magnetic topological insulators (MTIs) is the dissipative edge states, where quantized Hall resistance is accompanied by nonzero longitudinal resistance. We numerically investigate this dissipative behavior of QAHE in MTIs with a three-dimensional tight-binding model and non-equilibrium Green's function formalism. It is found that, in clean samples, the geometric mismatch between the detecting electrodes and the MTI sample leads to additional scattering in the central Hall bar, which is similar to the effect of splitting gates in the traditional Hall effect. As a result, while the Hall resistance remains quantized, the longitudinal resistance deviates from zero due to such additional scattering. It is also shown that external magnetic fields as well as disorder scattering can suppress the dissipation of the longitudinal resistance. These results are in good agreement with previous experimental observations and provide insight on the fabrication of QAHE devices.

Valley polarized topological kink states, existing broadly in the domain wall of hexagonal lattice systems, are identified in experiments. Unfortunately, only very limited physical properties are given. Using an Aharanov-Bohm interferometer composed of domain walls in graphene systems, we study the periodical modulation of a pure valley current in a large range by tuning the magnetic field or the Fermi level. For a monolayer graphene device, there exists one topological kink state, and the oscillation of the transmission coefficients has a single period. The π Berry phase and the linear dispersion relation of kink states can be extracted from the transmission data. For a bilayer graphene device, there are two topological kink states with two oscillation periods. Our proposal provides an experimentally feasible route to manipulate and characterize the valley-polarized topological kink states in classical wave and electronic graphene-type crystalline systems.

The aim of the present study was to investigate the role of microRNA (miR)‑21 in regulating collagen I and Smad7 expression in activated rat hepatic stellate cells (HSCs). Rat HSCs were isolated by single‑step density gradient centrifugation with Nycodenz. Cellular content of miR‑21, SMAD7, α‑smooth muscle actin (α‑SMA), collagen type I alpha 1 (COLLA1) and COLL alpha 2 (A2) mRNA was examined by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), and cellular content of Smad7 and α‑SMA protein was detected by western blotting. Binding of miR‑21 to the 3'‑untranslated region (UTR) of Smad7 was verified by dual‑luciferase assay. The authors observed that, in activated HSCs, expression of miR‑21 was significantly increased in a time‑dependent manner, while expression of Smad7 mRNA and protein was significantly reduced. In addition, miR‑21 mimics significantly enhanced cellular α‑SMA mRNA and protein content, while miR‑21 inhibitor significantly reduced α‑SMA mRNA and protein levels. Similarly, cellular content of COLLA1 and COLLA2 mRNA was significantly elevated by miR‑21 mimics, but reduced by miR‑21 inhibitor, in activated HSCs. Moreover, cellular content of Smad7 mRNA and protein was significantly reduced by miR‑21 mimics, but significantly increased by miR‑21 inhibitor. Furthermore, miR‑21 mimics activated firefly luciferase in HEK293 cells transfected with the wild type 3'‑UTR of Smad7. miR‑21 regulates expression of α‑SMA and collagen I in activated rat HSCs by directly targeting Smad7.

This study aimed to investigate the role of miR-138 in human coronary artery endothelial cell (HCAEC) injury and inflammatory response and the involvement of the PI3K/Akt/eNOS signalling pathway. Oxidized low-density lipoprotein (OX-LDL)-induced HCAEC injury models were established and assigned to blank, miR-138 mimic, miR-138 inhibitor, LY294002 (an inhibitor of the PI3K/Akt/eNOS pathway), miR-138 inhibitor + LY294002 and negative control (NC) groups. qRT-PCR and Western blotting were performed to detect the miR-138, PI3K, Akt and eNOS levels and the protein expressions of PI3K, Akt, eNOS, p-Akt, p-eNOS, Bcl-2, Bax and caspase-3. ELISAs were employed to measure the expressions of TNF-α, IL-4, IL-6, IL-8, IL-10 and nitric oxide (NO) and the activities of lactate dehydrogenase (LDH) and eNOS. MTT and flow cytometry were performed to assess the proliferation and apoptosis of HCAECs. Compared to the blank group, PI3K, Akt and eNOS were down-regulated in the miR-138 mimic and LY294002 groups but were up-regulated in the miR-138 inhibitor group. The miR-138 mimic and LY294002 groups showed decreased concentrations of TNF-α, IL-6, IL-8 and NO and reduced activities of LDH and eNOS, while opposite trends were observed in the miR-138 inhibitor group. The concentrations of IL-4 and IL-10 increased in the miR-138 mimic and LY294002 groups but decreased in the miR-138 inhibitor group. The miR-138 mimic and LY294002 groups had significantly decreased cell proliferation and increased cell apoptosis compared to the blank group. These findings indicate that up-regulation of miR-138 alleviates HCAEC injury and inflammatory response by inhibiting the PI3K/Akt/eNOS signalling pathway., (© 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

The Josephson supercurrent through a hybrid Majorana-quantum dot-Majorana junction is investigated. We particularly analyze the effect of spin-selective coupling between the Majorana and quantum dot states, which only emerges in the topological phase and will influence the current through bent junctions and/or in the presence of magnetic fields in the quantum dot. We find that the characteristic behavior of the supercurrent through this system is quite counterintuitive, differing remarkably from the resonant tunneling, e.g. through the similar (normal phase) superconductor-quantum dot-superconductor junction. Our analysis is carried out under the influence of the full set-up parameters and for both the [Formula: see text] and [Formula: see text] periodic currents. The present study is expected to be relevant to the future exploration of applications of Majorana-nanowire circuits.

The present study was designed to investigate the role of circulating miRNA-21 ( miR-21 ) in vascular restenosis of lower extremity arterial occlusive disease (LEAOD) patients after interventional therapy. A total of 412 LEAOD patients were enrolled randomly in the present study. According to computed tomography angiography (CTA) and ankle-brachial index (ABI), patients were assigned into the restenosis group and the non-restenosis group. miR-21 expression was detected with quantitative real-time PCR (qRT-PCR) before and after patients underwent interventional therapy. A follow-up period of 6 months was achieved. A receiver operating characteristic (ROC) curve was drawn and the area under the curve (AUC) was calculated to assess the predictive value of miR-21 in vascular restenosis. Patients were older in the restenosis group than in the non-restenosis group. The percentages of patients with diabetes and hypertension were higher in the restenosis group than in the non-restenosis group, and the Fontaine stage exhibited a significant difference between the two groups. miR-21 expression was higher in the restenosis group than in the non-restenosis group. miR-21 expression level was related to age, diabetes and hypertension in the restenosis group. Using miR-21 to predict vascular restenosis yielded an AUC of 0.938 (95% confidence interval (CI): 0.898-0.977), with Youden index of 0.817, sensitivity of 83.5% and specificity of 98.2%. Logistic regression analysis revealed that diabetes and miR-21 expression were the major risk factors for vascular restenosis of LEAOD. miR-21 can be used as a predictive indicator for vascular restenosis of LEAOD after interventional therapy., (© 2017 The Author(s).)

There is currently a lack of reliable, reproducible, and easily applied methods for assessing changes in liver histology in patients in the gray zone phase of chronic hepatitis B (CHB). Therefore, we aimed to develop a novel predictive scoring system to detect significant liver histological changes in these patients.A total of 388 patients in the gray zone phase of CHB who underwent liver biopsy were divided into a training group and a validation group, and their clinical and routinely available laboratory parameters were analyzed using univariate analysis, Spearman correlation analysis, and logistic modeling. A novel scoring system, termed the Significant Histological Model (SHM), was constructed using logistic modeling. The diagnostic accuracy of our novel scoring system was evaluated by the receiving operating characteristic (ROC) method, sensitivity, specificity, and positive and negative predictive values (NPVs).We established the novel SHM scoring system using serum aspartate transaminase (AST), platelet counts (PLTs), albumin (ALB), and hepatitis B virus (HBV) DNA (log10 IU/mL) levels. The area under the ROC curve of the SHM scoring system was 0.763 in the training group and 0.791 in the validation group. For patients with a score of -1.0 or less and no significant histological changes, the sensitivity was 78.9%, specificity was 51.5%, positive predictive value (PPV) was 46.4%, and NPV was 82.0%. In the validation set, the sensitivity, specificity, PPV, and NPV were 80.0%, 66.6%, 56.3%, and 86.2%, respectively.This novel scoring system using AST, PLT, ALB, and HBV DNA (log10 IU/mL) levels identifies patients in the gray zone phase of CHB with and without histological changes with a high degree of accuracy. Here, we provide the experimental basis for the initiation of clinical antiviral treatment without the need for liver biopsy.

MicroRNAs (miRNAs) are deregulated in various vascular ailments including abdominal aortic aneurysm (AAA). MiR-103 is involved in vascular, metabolic, and malignant diseases, but whether it participates in the pathogenesis of AAA remains elusive. ADAM10 plays a vital role in the formation of aneurysm, but whether miRs modulate its activity during AAA formation is totally unknown. In this study, we detected the significantly increased protein expression of ADAM10 in angiotensin II induced murine AAA specimens, while the mRNA expression of ADAM10 was similar between AAA and control, suggesting the posttranscriptional regulation. The ADAM10 specific inhibitor GI254023X dramatically reduced the macrophage infiltration of murine abdominal aorta. Bioinformatic predictions suggest that ADAM10 is the target of miR-103a/107 but the binding site is exclusive. At the cellular level, miR-103a-1 suppressed the protein expression of ADAM10, while antisense miR-103a-1 increased its expression. Particularly, with the progression of murine AAA, the mRNA expression of miR-103a/107 substantially decreased and the protein expression of ADAM10 greatly increased. Together, our data afford the new insight that miR-103a inhibited AAA growth via targeting ADAM10, which might be a promising therapeutic strategy to alleviate AAA., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this paper.

Aim: To investigate the role of Gadd45a in hepatic fibrosis and the transforming growth factor (TGF)-β/Smad signaling pathway., Methods: Wild-type male BALB/c mice were treated with CCl4 to induce a model of chronic liver injury. Hepatic stellate cells (HSCs) were isolated from the liver of BALB/c mice and were treated with small interfering RNAs (siRNAs) targeting Gadd45a or the pcDNA3.1-Gadd45a recombinant plasmid. Cellular α-smooth muscle actin (α-SMA), β-actin, type I collagen, phospho-Smad2, phospho-Smad3, Smad2, Smad3, and Smad4 were detected by Western blots. The mRNA levels of α-SMA, β-actin, and type I collagen were determined by quantitative real-time (qRT)-PCR analyses. Reactive oxygen species production was monitored by flow cytometry using 2,7-dichlorodihydrofluorescein diacetate. Gadd45a, Gadd45b, anti-Gadd45g, type I collagen, and SMA local expression in liver tissue were measured by histologic and immunohistochemical analyses., Results: Significant downregulation of Gadd45a, but not Gadd45b or Gadd45g, accompanied by activation of the TGF-β/Smad signaling pathways was detected in fibrotic liver tissues of mice and isolated HSCs with chronic liver injury induced by CCl4 treatment. Overexpression of Gadd45a reduced the expression of extracellular matrix proteins and α-SMA in HSCs, whereas transient knockdown of Gadd45a with siRNA reversed this process. Gadd45a inhibited the activity of a plasminogen activator inhibitor-1 promoter construct and (CAGA)9 MLP-Luc, an artificial Smad3/4-specific reporter, as well as reduced the phosphorylation and nuclear translocation of Smad3. Gadd45a showed protective effects by scavenging reactive oxygen species and upregulating antioxidant enzymes., Conclusion: Gadd45a may counteract hepatic fibrosis by regulating the activation of HSCs via the inhibition of TGF-β/Smad signaling.

The Weyl semimetal (WSM) is a newly proposed quantum state of matter. It has Weyl nodes in bulk excitations and Fermi arc surface states. We study the effects of disorder and localization in WSMs and find three novel phase transitions. (i) Two Weyl nodes near the Brillouin zone boundary can be annihilated pairwise by disorder scattering, resulting in the opening of a topologically nontrivial gap and a transition from a WSM to a three-dimensional quantum anomalous Hall state. (ii) When the two Weyl nodes are well separated in momentum space, the emergent bulk extended states can give rise to a direct transition from a WSM to a 3D diffusive anomalous Hall metal. (iii) Two Weyl nodes can emerge near the zone center when an insulating gap closes with increasing disorder, enabling a direct transition from a normal band insulator to a WSM. We determine the phase diagram by numerically computing the localization length and the Hall conductivity, and propose that the novel phase transitions can be realized on a photonic lattice.

The Goos-Hänchen (GH) shift and the Imbert-Fedorov (IF) shift are optical phenomena which describe the longitudinal and transverse lateral shifts at the reflection interface, respectively. Here, we predict the GH and IF shifts in Weyl semimetals (WSMs)-a promising material harboring low energy Weyl fermions, a massless fermionic cousin of photons. Our results show that the GH shift in WSMs is valley independent, which is analogous to that discovered in a 2D relativistic material-graphene. However, the IF shift has never been explored in nonoptical systems, and here we show that it is valley dependent. Furthermore, we find that the IF shift actually originates from the topological effect of the system. Experimentally, the topological IF shift can be utilized to characterize the Weyl semimetals, design valleytronic devices of high efficiency, and measure the Berry curvature.

The quantum entanglement between two qubits is crucial for applications in the quantum communication. After the entanglement of photons was experimentally realized, much effort has been taken to exploit the entangled electrons in solid-state systems. Here, we propose a Cooper-pair splitter, which can generate spatially-separated but entangled electrons, in a quantum anomalous Hall insulator proximity-coupled with a superconductor. After coupling with a superconductor, the chiral edge states of the quantum anomalous Hall insulator can still survive, making the backscattering impossible. Thus, the local Andreev reflection becomes vanishing, while the crossed Andreev reflection becomes dominant in the scattering process. This indicates that our device can serve as an extremely high-efficiency Cooper-pair splitter. Furthermore, because of the chiral characteristic, our Cooper-pair splitter is robust against disorders and can work in a wide range of system parameters. Particularly, it can still function even if the system length exceeds the superconducting coherence length.

Exciton superfluid is a macroscopic quantum phenomenon in which large quantities of excitons undergo the Bose-Einstein condensation. Recently, exciton superfluid has been widely studied in various bilayer systems. However, experimental measurements only provide indirect evidence for the existence of exciton superfluid. In this article, by viewing the exciton in a bilayer system as an electric dipole, we derive the London-type and Ginzburg-Landau-type equations for the electric dipole superconductors. By using these equations, we discover the Meissner-type effect and the electric dipole current Josephson effect. These effects can provide direct evidence for the formation of the exciton superfluid state in bilayer systems and pave new ways to drive an electric dipole current.

Based on a two-band Chern insulator with Chern number n = 2, we study the transport properties and the topological phase transition induced by either an external magnetic field or disorder. In this paper, a characteristic topological phase transition from n = 2 to n = 0, which is in sharp contrast to the plateau-plateau transition in the integer quantum Hall effect, is observed. This unique feature of the phase transition should be ascribed to the minimal two-band feature of this high Chern insulator. We prove this result by studying the transport properties of many different geometrical structures and the evolution of the Chern number in the presence of magnetic fields and strong disorder.

We revisit the spin-injected field effect transistor (spin-FET) in a framework of the lattice model by applying the recursive lattice Green's function approach. In the one-dimensional case the results of simulations in coherent regime reveal noticeable differences from the celebrated Datta-Das model, which lead us to an improved treatment with generalized result. The simulations also allow us to address inelastic scattering and lateral confinement effects in the control of spins. These issues are very important in the spin-FET device.

We construct a theoretical model to study the orbital Kondo effect in a parallel double quantum dot (DQD). Recently, pseudospin-resolved transport spectroscopy of the orbital Kondo effect in a DQD has been experimentally reported. The experiment revealed that when interdot tunneling is ignored, two and one Kondo peaks exist in the conductance-bias curve for pseudospin-non-resolved and pseudospin-resolved cases, respectively. Our theoretical studies reproduce this experimental result. We also investigate the case of all lead voltages being non-equal (the complete pseudospin-resolved case) and found that there are at most four Kondo peaks in the curve of the conductance versus the pseudospin splitting energy. When interdot tunneling is introduced, some new Kondo peaks and dips can emerge. Furthermore, the pseudospin transport and the pseudospin flipping current are also studied in the DQD system. Since the pseudospin transport is much easier to control and measure than the real spin transport, it can be used to study the physical phenomenon related to the spin transport.

We report on a theoretical study of spin-dependent electron transport through single-helical molecules connected by two nonmagnetic electrodes, and explain the experiment of significant spin-selective phenomenon observed in α-helical protein and the contradictory results between the protein and single-stranded DNA. Our results reveal that the α-helical protein is an efficient spin filter and the spin polarization is robust against the disorder. These results are in excellent agreement with recent experiments [Mishra D, et al. (2013) Proc Natl Acad Sci USA 110(37):14872-14876; Göhler B, et al. (2011) Science 331(6019):894-897] and may facilitate engineering of chiral-based spintronic devices.

We analyze the dephasing effect on the backscattering behavior of the helical surface states in 3D topological insulators. We show that the combination of dephasing and impurity scattering can cause backscattering in the helical states. Especially for the charge impurity case, the backscattering cross section becomes extremely large around the Dirac point. This large backscattering behavior can lead to the anomalous "gaplike" features found in recent experiments [T. Sato et al., Nat. Phys. 7, 840 (2011)].

Using the Landauer-Büttiker formula, we study the effect of dephasing on the transport properties of the HgTe/CdTe p-n junction. It is found that in the HgTe/CdTe p-n junction the topologically protected gapless helical edge states manifest a quantized 2e²/h plateau robust against dephasing, in sharp contrast to the case for the normal HgTe/CdTe quantum well. This robustness of the transport properties of the edge states against dephasing should be attributed to the special construction of the HgTe/CdTe p-n junction, which limits the gapless helical edge states to a very narrow region and thus weakens the influence of the dephasing on the gapless edge states to a large extent. Our results demonstrate that the p-n junction could be a substitute device for use in experimentally observing the robust edge states and quantized plateau. Finally, we present a feasible scheme based on current experimental methods.

We first bring up the concept of the spin-current Seebeck effect based on a recent experiment (Vera-Marun et al 2012 Nature Phys. 8 313), and investigate the spin-current Seebeck effect in quantum dot (QD) systems. Our results show that the spin-current Seebeck coefficient S is sensitive to different polarization states of the QD, and therefore can be used to detect the polarization state of the QD and monitor the transitions between different polarization states of the QD. The intradot Coulomb interaction can greatly enhance S due to the stronger polarization of the QD. By using the parameters for a typical QD whose intradot Coulomb interaction U is one order of magnitude larger than the linewidth Γ, we demonstrate that the maximum value of S can be enhanced by a factor of 80. On the other hand, for a QD whose Coulomb interaction is negligible, we show that one can still obtain a large S by applying an external magnetic field.

Background: This study aimed to determine the efficacy and safety of recombinant Mycobacterium tuberculosis ESAT-6 protein for diagnosis of pulmonary tuberculosis (TB)., Material and Methods: A phase II trial was performed in 158 patients with pulmonary TB (145 initially-treated and 13 re-treated) and 133 healthy subjects. Skin testing was carried out by injecting purified protein derivative (PPD) (on left forearm) or recombinant ESAT-6 protein at a dosage of 2, 5, or 10 μg/mL (on the right forearm) in each subject. Reaction activity and adverse events were monitored at 24, 48, and 72 h following the injection. Receiver operating characteristic curves were plotted to determine the areas under the curves (AUCs) and the cut-off induration diameters for the optimal diagnostic performance., Results: The reaction activity was significantly increased upon recombinant ESAT-6 injection in pulmonary TB patients compared with healthy subjects. In pulmonary TB patients, the reaction was dose-dependent, and at 48 h, 10 μg/mL recombinant ESAT-6 produced a reaction similar to that produced by PPD. The AUCs for a 10 μg/mL dosage were 0.9823, 0.9552, and 0.9266 for 24 h, 48 h, and 72 h, respectively, and the induration diameters of 4.5-5.5 mm were the optimal trade-off values between true positive rates and false positive rates. No serious adverse events occurred in any subjects., Conclusions: Recombinant ESAT-6 protein is efficacious and safe for diagnosing pulmonary TB. Based on the reaction, performance, safety, and practicability, we recommend that 10 μg/mL at 48 h with an induration cut-off value of 5.0 mm be used.

We propose a scheme to generate metal-insulator transition in the random binary layer (RBL) model, which is constructed by randomly assigning two types of layers along the longitudinal direction. Based on a tight-binding Hamiltonian, the localization length is calculated for a variety of RBLs with different cross section geometries by using the transfer-matrix method. Both analytical and numerical results show that a band of extended states could appear in the quasi-one-dimensional RBLs and the systems behave as metals by properly tuning the model parameters, due to the existence of a completely ordered subband, leading to a metal-insulator transition in parameter space. Furthermore, the extended states are irrespective of the diagonal and off-diagonal disorder strengths. Our results can be generalized to two- and three-dimensional disordered systems with arbitrary layer structures, and may be realized in Bose-Einstein condensates.