Measuring the phonon-assisted spectral function by using a non-quilibrium three-terminal single-molecular device

The electron transport through a three-terminal single-molecular transistor (SMT) is theoretically studied. We find that the differential conductance of the third and weakly coupled terminal versus its voltage matches well with the spectral function versus the energy when certain conditions are met. Particularly, this excellent matching is maintained even for complicated structure of the phonon-assisted side peaks. Thus, this device offers an experimental approach to explore the shape of the phonon-assisted spectral function in detail. In addition we discuss the conditions of a perfect matching. The results show that at low temperatures the matching survives regardless of the bias and the energy levels of the SMT. However, at high temperatures, the matching is destroyed.Comment: 9 pages, 5 figure

Building topological device through emerging robust helical surface states

We propose a nonlocal manipulation method to build topological devices through emerging robust helical surface states in Z_2=0 topological systems. Specifically, in a ribbon of Z_2=0 Bernevig- Hughes-Zhang (BHZ) model with finite-size effect, if magnetic impurities are doped on the top (bottom) edge, the edge states on the bottom (top) edge can be altered according to the strengths and directions of these magnetic impurities. Consequently, the backscattering between the emerging robust helical edge states and gapped normal edge states due to finite-size confinement is also changed, which makes the system alternate between a perfect one-channel conductor and a perfect insulator. This effect allows us to fabricate topological devices with high on-off ratio. Moreover, it can also be generalized to 3D model and more realistic Cd3As2 type Dirac semimetals.Comment: 7 pages, 6 figure

One-dimensional quantum channel in a graphene line defect

Using a tight-binding model, we study a line defect in graphene where a bulk energy gap is opened by sublattice symmetry breaking. It is found that sublattice symmetry breaking may induce many configurations that correspond to different band spectra. In particular, a gapless state is observed for a configuration which hold a mirror symmetry with respect to the line defect. We find that this gapless state originates from the line defect and is independent of the width of the graphene ribbon, the location of the line defect, and the potentials in the edges of the ribbon. In particular, the gapless state can be controlled by the gate voltage embedded below the line defect. Finally, this result is supported with conductance calculations. This study shows how a quantum channel could be constructed using a line defect, and how the quantum channel can be controlled by tuning the gate voltage embedded below the line defect.Comment: 8 pages, 10 figure

Proteomic Analysis of Turnip Crinkle Virus-Infected Tobacco using 2-D Gel Electrophoresis

Master'sMASTER OF SCIENC

Pre-existing Proton Pump Inhibitor Treatment and Short-Term Prognosis of Acute Myocardial Infarction Patients

IntroductionEvidence suspects proton pump inhibitor (PPI) use is a risk factor of poor prognosis of acute myocardial infarction (AMI). We aimed to investigate the association between pre-existing PPI use before emergency department (ED) visit and short-term prognosis of AMI patients.Materials and MethodsAMI patients admitted to ED were included and categorized as cohorts with or without pre-existing PPI use. Hospital mortality, length of hospital stay, being admitted to intensive care unit (ICU), and length of (total) ICU stay were studied as prognostic outcomes. Multivariable logistic regression or linear regression were used to estimate the associations between pre-existing PPI use and the outcomes after adjusting for potential confounders.ResultsA total of 2001 AMI patients were included. No significant difference was found in hospital mortality and length of ICU stay between cohorts; patients with pre-existing PPI use showed a significantly longer length of hospital stay (median 3.81 vs. 3.20 days, P = 0.002) but lower proportion of being admitted to ICU (25.59% vs. 40.83%, P < 0.001) compared to those without pre-existing PPI use. Pre-existing PPI use was not associated with hospital mortality [odds ratio (OR) 1.08, 95% confidence interval (CI) 0.58–1.99], length of hospital stay (β = 0.23, 95% CI −0.35 to 0.82), and length of ICU stay (β = −0.18, 95% CI −1.06 to 0.69), but was statistically significantly associated with lower risk of being admitted to ICU (OR 0.69, 95% CI 0.52–0.92).ConclusionThe current study does not support newly diagnosed AMI patients with pre-existing PPI use before ED visit would experience worse short-term prognosis than those without

Preparation of a low viscosity urethane-based composite for improved dental restoratives

Several new urethane-based dimethacrylates were synthesized, characterized and used to formulate the resin composites. Compressive strength (CS) was used as a screen tool to evaluate the mechanical property of the formed composites. Flexural strength, diametral tensile strength, water sorption, degree of conversion and shrinkage of the composites were also evaluated. The results show that most of the synthesized urethane-based dimethacrylates were solid, which are not suitable to dental filling restorations. However, it was found that liquid urethane-based dimethacrylates could be derivatized using asymmetrical methacrylate synthesis. Not only the newly synthesized urethane-based dimethacrylates showed lower viscosity values but also their constructed composites exhibited higher mechanical strengths. Without triethyleneglycol dimethacrylate (TEGDMA) addition, the new urethane-constructed composites showed significantly lower water sorption and shrinkage

Disorder and metal-insulator transitions in Weyl semimetals

The Weyl semimetal (WSM) is a newly proposed quantum state of matter. It has Weyl nodes in bulk excitations and Fermi arcs surface states. We study the effects of disorder and localization in WSMs and find three exotic 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 (3D) 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 exotic phase transitions can be realized on a photonic lattice.Comment: 7 pages with appendix, 6 figure