1,793 research outputs found

    Complete gate control of supercurrent in graphene p-n junctions

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    In a conventional Josephson junction of graphene, the supercurrent is not turned off even at the charge neutrality point, impeding further development of superconducting quantum information devices based on graphene. Here we fabricate bipolar Josephson junctions of graphene, in which a p-n potential barrier is formed in graphene with two closely spaced superconducting contacts, and realize supercurrent ON/OFF states using electrostatic gating only. The bipolar Josephson junctions of graphene also show fully gate-driven macroscopic quantum tunnelling behaviour of Josephson phase particles in a potential well, where the confinement energy is gate tuneable. We suggest that the supercurrent OFF state is mainly caused by a supercurrent dephasing mechanism due to a random pseudomagnetic field generated by ripples in graphene, in sharp contrast to other nanohybrid Josephson junctions. Our study may pave the way for the development of new gate-tuneable superconducting quantum information devices.open114344sciescopu

    Electromagnetic performances and main parameter sensitivity effect on unbalance magnetic flux in a New Single‑Phase FEFSM with segmental rotor

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    Three-phase field excitation flux switching motor (FEFSM) with salient rotor structure has been introduced with their advantages of rotor easy temperature elimination and controllable FEC magnetic flux. Yet, the salient rotor structure is found to lead a longer magnetic flux path between stator and rotor parts, producing a weak flux linkage along with low torque performances. Hence, a new structure of single-phase FEFSM using segmental rotor with non-overlap windings is proposed with advantages of shorter magnetic flux path, light weight and robust rotor structure. Analysis on fundamental magnetic flux characteristics, armature and FEC magnetic flux linkages, cogging torque, back-Emf, various torque capabilities, refinement of unbalance magnetic flux, and torque-power versus speed characteristics are conducted using 2D FEA through JMAG Designer version 15. The results show that magnetic flux amplitude ratio has been improved by 41.2% while the highest torque and power achieved are 1.45 Nm and 343.8 W, respectively

    Antioxidant, antibacterial and α-glucosidase inhibitory activities of different extracts of Cortex Moutan

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    Different extracts of Cortex Moutan (CM) were investigated for their antioxidant, antibacterial and α- glucosidase inhibitory activities. The content of paeonol was quantified by high performance liquid chromatography (HPLC). The results show that the yield of acetone extract (57.14%) was significantly higher than those of other solvents. The ethyl-acetate extract exhibited maximum paeonol concentration (60.69 μg/ml), good antibacterial activities (MIC = 100 μg/ml) against Escherichia coli and possessed significant α-glucosidase inhibitory activity. In addition, among all of the extracts, ethylacetate extract demonstrated a high total phenolic value of 127.12 ± 1.42 mg GAE/g, high DPPH radical scavenging activity with an IC50 of 19.88 ± 0.26 μg/ml, and significant reducing power, suggesting that CM is a potential source of natural antioxidants.Key words: Cortex Moutan, antioxidant, 11-diphenyl-2-picrylhydrazyl hydrate (DPPH), reducing power, antibacterial, α-glucosidas

    Influences of H on the Adsorption of a Single Ag Atom on Si(111)-7 × 7 Surface

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    The adsorption of a single Ag atom on both clear Si(111)-7 × 7 and 19 hydrogen terminated Si(111)-7 × 7 (hereafter referred as 19H-Si(111)-7 × 7) surfaces has been investigated using first-principles calculations. The results indicated that the pre-adsorbed H on Si surface altered the surface electronic properties of Si and influenced the adsorption properties of Ag atom on the H terminated Si surface (e.g., adsorption site and bonding properties). Difference charge density data indicated that covalent bond is formed between adsorbed Ag and H atoms on 19H-Si(111)-7 × 7 surface, which increases the adsorption energy of Ag atom on Si surface

    The interplay of microscopic and mesoscopic structure in complex networks

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    Not all nodes in a network are created equal. Differences and similarities exist at both individual node and group levels. Disentangling single node from group properties is crucial for network modeling and structural inference. Based on unbiased generative probabilistic exponential random graph models and employing distributive message passing techniques, we present an efficient algorithm that allows one to separate the contributions of individual nodes and groups of nodes to the network structure. This leads to improved detection accuracy of latent class structure in real world data sets compared to models that focus on group structure alone. Furthermore, the inclusion of hitherto neglected group specific effects in models used to assess the statistical significance of small subgraph (motif) distributions in networks may be sufficient to explain most of the observed statistics. We show the predictive power of such generative models in forecasting putative gene-disease associations in the Online Mendelian Inheritance in Man (OMIM) database. The approach is suitable for both directed and undirected uni-partite as well as for bipartite networks

    Solution-processed n-type fullerene field-effect transistors prepared using CVD-grown graphene electrodes: improving performance with thermal annealing

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    Solution-processed organic field effect transistors (OFETs), which are amenable to facile large-area processing methods, have generated significant interest as key elements for use in all-organic electronic applications aimed at realizing low-cost, lightweight, and flexible devices. The low performance levels of n-type solution-processed bottom-contact OFETs unfortunately continue to pose a barrier to their commercialization. In this study, we introduced a combination of CVD-grown graphene source/drain (S/D) electrodes and fullerene (C-60) in a solution-processable n-type semiconductor toward the fabrication of n-type bottom-contact OFETs. The C-60 coating in the channel region was achieved by modifying the surface of the oxide gate dielectric layer with a phenyl group-terminated self-assembled monolayer (SAM). The graphene and phenyl group in the SAMs induced pi-pi interactions with C-60, which facilitated the formation of a C-60 coating. We also investigated the effects of thermal annealing on the reorganization properties and field-effect performances of the overlaying solution-processed C-60 semiconductors. We found that thermal annealing of the C-60 layer on the graphene surface improved the crystallinity of the face-centered cubic (fcc) phase structure, which improved the OFET performance and yielded mobilities of 0.055 cm(2) V-1 s(-1). This approach enables the realization of solution-processed C-60-based FETs using CVD-grown graphene S/D electrodes via inexpensive and solution-process techniques.open1166sciescopu

    Remote Manipulation of Droplets on a Flexible Magnetically Responsive Film

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    The manipulation of droplets is used in a wide range of applications, from lab-on-a-chip devices to bioinspired functional surfaces. Although a variety of droplet manipulation techniques have been proposed, active, fast and reversible manipulation of pure discrete droplets remains elusive due to the technical limitations of previous techniques. Here, we describe a novel technique that enables active, fast, precise and reversible control over the position and motion of a pure discrete droplet with only a permanent magnet by utilizing a magnetically responsive flexible film possessing actuating hierarchical pillars on the surface. This magnetically responsive surface shows reliable actuating capabilities with immediate field responses and maximum tilting angles of ???90??. Furthermore, the magnetic responsive film exhibits superhydrophobicity regardless of tilting angles of the actuating pillars. Using this magnetically responsive film, we demonstrate active and reversible manipulation of droplets with a remote magnetic force.open0

    Churg-Strauss syndrome following cessation of allergic desensitization vaccination: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Churg-Strauss syndrome is a vasculitis of medium to small sized vessels. Diagnosis is mainly clinical with findings of asthma, eosinophilia, rhinosinusitis and signs of vasculitis in major organs.</p> <p>Case presentation</p> <p>We present a case of a 19-year-old Persian male who developed signs and symptoms of this syndrome related to hyposensitization treatments for allergy control.</p> <p>Conclusions</p> <p>No unifying etiology for the disease can be presented as it is found associated with environmental factors, medications, infections and is even considered a variant of asthma with predisposition to vasculitic involvement. Therefore, it is important to recognize this disease and be aware of underdiagnosis because of emphasis on pathologic evidence. Here, we present a case of allergic desensitization causing Churg-Strauss syndrome in the absence of other known factors.</p

    Expression and Differential Responsiveness of Central Nervous System Glial Cell Populations to the Acute Phase Protein Serum Amyloid A

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    Acute-phase response is a systemic reaction to environmental/inflammatory insults and involves hepatic production of acute-phase proteins, including serum amyloid A (SAA). Extrahepatically, SAA immunoreactivity is found in axonal myelin sheaths of cortex in Alzheimer's disease and multiple sclerosis (MS), although its cellular origin is unclear. We examined the responses of cultured rat cortical astrocytes, microglia and oligodendrocyte precursor cells (OPCs) to master pro-inflammatory cytokine tumour necrosis factor (TNF)-\u3b1 and lipopolysaccaride (LPS). TNF-\u3b1 time-dependently increased Saa1 (but not Saa3) mRNA expression in purified microglia, enriched astrocytes, and OPCs (as did LPS for microglia and astrocytes). Astrocytes depleted of microglia were markedly less responsive to TNF-\u3b1 and LPS, even after re-addition of microglia. Microglia and enriched astrocytes showed complementary Saa1 expression profiles following TNF-\u3b1 or LPS challenge, being higher in microglia with TNF-\u3b1 and higher in astrocytes with LPS. Recombinant human apo-SAA stimulated production of both inflammatory mediators and its own mRNA in microglia and enriched, but not microglia-depleted astrocytes. Co-ultramicronized palmitoylethanolamide/luteolin, an established anti-inflammatory/neuroprotective agent, reduced Saa1 expression in OPCs subjected to TNF-\u3b1 treatment. These last data, together with past findings suggest that co-ultramicronized palmitoylethanolamide/luteolin may be a novel approach in the treatment of inflammatory demyelinating disorders like MS
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