Unveiling the Direct Correlation between the CVD-Grown Graphene and the Growth Template

Chemical vapor deposition (CVD) is known to produce continuous, large-area graphene sheet with decent physical properties. In the CVD process, catalytic metal substrates are typically used as the growth template, and copper has been adopted as the representative material platform due to its low carbon solubility and resulting monolayer graphene growth capability. For the widespread industrial applications of graphene, achieving the high-quality is essential. Several factors affect the qualities of CVD-grown graphene, such as pressure, temperature, carbon precursors, or growth template. In this work, we provide detailed analysis on the direct relation between the metallic growth substrate (copper) and overall properties of the resulting CVD-grown graphene. The surface morphology of copper substrate was modulated via simple chemical treatments, and its effect on physical, optical, and electrical properties of graphene was analyzed. Based on these results, we propose a simple synthesis route to produce high-quality, continuous, monolayer graphene sheet, which can facilitate the commercialization of CVD graphene into realit

Dynamic behavior of driven interfaces in models with two absorbing states

We study the dynamics of an interface (active domain) between different absorbing regions in models with two absorbing states in one dimension; probabilistic cellular automata models and interacting monomer-dimer models. These models exhibit a continuous transition from an active phase into an absorbing phase, which belongs to the directed Ising (DI) universality class. In the active phase, the interface spreads ballistically into the absorbing regions and the interface width diverges linearly in time. Approaching the critical point, the spreading velocity of the interface vanishes algebraically with a DI critical exponent. Introducing a symmetry-breaking field $h$ that prefers one absorbing state over the other drives the interface to move asymmetrically toward the unpreferred absorbing region. In Monte Carlo simulations, we find that the spreading velocity of this driven interface shows a discontinuous jump at criticality. We explain that this unusual behavior is due to a finite relaxation time in the absorbing phase. The crossover behavior from the symmetric case (DI class) to the asymmetric case (directed percolation class) is also studied. We find the scaling dimension of the symmetry-breaking field $y_h = 1.21(5)$.Comment: 5 pages, 5 figures, Revte

Schottky Barrier Modulation of Metal/4H-SiC Junction with Thin Interface Spacer Driven by Surface Polarization Charge on 4H-SiC Substrate

The Au/Ni/Al2O3/4H-SiC junction with the Al2O3 film as a thin spacer layer was found to show the electrical characteristics of a typical rectifying Schottky contact, which is considered to be due to the leakiness of the spacer layer. The Schottky barrier of the junction was measured to be higher than an Au/Ni/4H-SiC junction with no spacer layer. It is believed that the negative surface bound charge originating from the spontaneous polarization of 4H-SiC causes the Schottky barrier increase. The use of a thin spacer layer can be an efficient experimental method to modulate Schottky barriers of metal/4H-SiC junctions.open

Critical phenomena of nonequilibrium dynamical systems with two absorbing states

We study nonequilibrium dynamical models with two absorbing states: interacting monomer-dimer models, probabilistic cellular automata models, nonequilibrium kinetic Ising models. These models exhibit a continuous phase transition from an active phase into an absorbing phase which belongs to the universality class of the models with the parity conservation. However, when we break the symmetry between the absorbing states by introducing a symmetry-breaking field, Monte Carlo simulations show that the system goes back to the conventional directed percolation universality class. In terms of domain wall language, the parity conservation is not affected by the presence of the symmetry-breaking field. So the symmetry between the absorbing states rather than the conservation laws plays an essential role in determining the universality class. We also perform Monte Carlo simulations for the various interface dynamics between different absorbing states, which yield new universal dynamic exponents. With the symmetry-breaking field, the interface moves, in average, with a constant velocity in the direction of the unpreferred absorbing state and the dynamic scaling exponents apparently assume trivial values. However, we find that the hyperscaling relation for the directed percolation universality class is restored if one focuses on the dynamics of the interface on the side of the preferred absorbing state only.Comment: 11 pages, 21 figures, Revtex, submitted to Phy. Rev.

Reentrant phase diagram of branching annihilating random walks with one and two offsprings

We investigate the phase diagram of branching annihilating random walks with one and two offsprings in one dimension. A walker can hop to a nearest neighbor site or branch with one or two offsprings with relative ratio. Two walkers annihilate immediately when they meet. In general, this model exhibits a continuous phase transition from an active state into the absorbing state (vacuum) at a finite hopping probability. We map out the phase diagram by Monte Carlo simulations which shows a reentrant phase transition from vacuum to an active state and finally into vacuum again as the relative rate of the two-offspring branching process increases. This reentrant property apparently contradicts the conventional wisdom that increasing the number of offsprings will tend to make the system more active. We show that the reentrant property is due to the static reflection symmetry of two-offspring branching processes and the conventional wisdom is recovered when the dynamic reflection symmetry is introduced instead of the static one.Comment: 14 pages, Revtex, 4 figures (one PS figure file upon request) (submitted to Phy. Rev. E

Optimum dietary processed sulfur (Immuno-F) level has antibiotic effects on the growth, hematology and disease resistance of juvenile olive flounder, Paralichthys olivaceus

Author's accepted version (postprint).This is an Accepted Manuscript of an article published by Elsevier in Animal Feed Science and Technology on 19/07/2021.Available online: https://www.sciencedirect.com/science/article/pii/S0377840121002212?via%3DihubA great deal of research has been focused on feed additives that can boost the immune system of cultured fish since the food and drug administration (FDA) banned the use of antibiotics as feed supplementations in 2017. Sulfur is generally an essential element for the growth of animals, and sulfur-containing compounds are known to have anti-oxidant and anti-bactericidal effects. Although dietary sulfur has many potentials as a functional additive as well as an antibiotic replacer, it can also be toxic when supplemented at the high levels. Thus, it is necessary to determine the optimum amount in fish diet to exert positive effects on immune responses. Hence, an 8-week feeding trial was conducted to evaluate the optimum dietary processed sulfur (Immuno-F) level to replace antibiotic oxytetracycline (OTC) in juvenile olive flounder based on growth performance, hematology, and disease resistance. Each of 20 fish averaging 12.6 ± 0.17 g (mean ± SD) were randomly allocated into 8 groups of three tanks, and fed one of the eight isonitrogenous and isocaloric (crude protein 46.7 %, 160 kJ g−1) experimental diets formulated by supplementing Immuno-F at 0 ppm (Cont), 25 ppm (F25), 50 ppm (F50), 250 ppm (F250), 500 ppm (F500), 1000 ppm (F1000) and 2000 ppm (F2000), or oxytetracycline 4000 ppm (OTC4000). Weight gain and specific growth rate of fish fed F25, F500, and OTC4000 diets were significantly higher than those of fish fed F1000 and F2000 diets. In addition, superoxide dismutase, lysozyme and myeloperoxidase activities were not significantly different between sulfur and OTC supplemented groups. However, serum triglyceride levels of fish fed F1000 diet were significantly higher than those of fish fed F25, F50, F250, F500 and OTC4000 diets. In challenge test against Edwardsiella tarda at the 6th day, cumulative survival rates of fish fed F50 diet were slightly higher than those of fish fed F250-F2000 diets. Therefore, these results indicate that dietary processed sulfur at 50 ppm supplementation could replace antibiotic (OTC) in juvenile olive flounder.acceptedVersio