826 research outputs found

    Comment on "Band structure engineering of graphene by strain: First-principles calculations"

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    In their first-principles calculations of the electronic band structure of graphene under uniaxial strain, Gui, Li, and Zhong [Phys. Rev. B \textbf{78}, 075435 (2008)] have found opening of band gaps at the Fermi level. This finding is in conflict with the tight-binding description of graphene which is closed gap for small strains. In this Comment, we present first-principles calculations which refute the claim that strain opens band gaps in graphene.Comment: published versio

    Energy gap opening in submonolayer lithium on graphene: Local density functional and tight-binding calculations

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    The adsorption of an alkali-metal submonolayer on graphene occupying every third hexagon of the honeycomb lattice in a commensurate (3×3)R30(\sqrt{3}\times\sqrt{3})R30^\circ arrangement induces an energy gap in the spectrum of graphene. To exemplify this type of band gap, we present \textit{ab initio} density functional theory calculations of the electronic band structure of C6_6Li. An examination of the lattice geometry of the compound system shows the possibility that the nearest-neighbor hopping amplitudes have alternating values constructed in a Kekul\'e-type structure. The band structure of the textured tight-binding model is calculated and shown to reproduce the expected band gap as well as other characteristic degeneracy removals in the spectrum of graphene induced by lithium adsorption. More generally we also deduce the possibility of energy gap opening in periodic metal on graphene compounds Cx_xM if xx is a multiple of 3.Comment: 7 pages, 5 figures, published versio

    Numerical simulation of the stochastic dynamics of inclusions in biomembranes in presence of surface tension

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    The stochastic dynamics of inclusions in a randomly fluctuating biomembrane is simulated. These inclusions can represent the embedded proteins and the external particles arriving at a cell membrane. The energetics of the biomembrane is modelled via the Canham-Helfrich Hamiltonian. The contributions of both the bending elastic-curvature energy and the surface tension of the biomembrane are taken into account. The biomembrane is treated as a two-dimensional sheet whose height variations from a reference frame is treated as a stochastic Wiener process. The lateral diffusion parameter associated with this Wiener process coupled with the longitudinal diffusion parameter obtained from the standard Einsteinian diffusion theory completely determine the stochastic motion of the inclusions. It is shown that the presence of surface tension significantly affects the overall dynamics of the inclusions, particularly the rate of capture of the external inclusions, such as drug particles, at the site of the embedded inclusions, such as the embedded proteins.Comment: 17 pages, 4 figures, to appear in physica

    Thermal conductivity of deformed carbon nanotubes

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    We investigate the thermal conductivity of four types of deformed carbon nanotubes by using the nonequilibrium molecular dynamics method. It is reported that various deformations have different influence on the thermal properties of carbon nanotubes. For the bending carbon nanotubes, the thermal conductivity is independent on the bending angle. However, the thermal conductivity increases lightly with XY-distortion and decreases rapidly with Z-distortion. The thermal conductivity does not change with the screw ratio before the breaking of carbon nanotubes but decreases sharply after the critical screw ratio.Comment: 6figure

    Independent and social living skills training for people with Schizophrenia in Iran: A randomized controlled trial

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    Objectives: Schizophrenia is responsible for a significant proportion of burden of mental diseases in Iran. Lack of a follow-up system has resulted in the repeated hospitalizations. In this study it is hypothesized that standardized living skills training delivered to participants with schizophrenia in outpatient and inpatient centers can be effective compared to a control group (with occupational therapy) in reducing psychopathology severity and increasing quality of life. Methods: This is a multi-centered parallel group randomized controlled trial in Iran and it is singleblinded. Eligible participants are randomly allocated into two groups in a 1:1 ratio. Participants are assigned by stratified balanced block randomization method. The trial is conducted in the cities of Tehran and Mashhad. Its aim is to recruit 160 clients with schizophrenia. The intervention for the experimental group is social living skills training. The intervention for the control group is occupational therapy. The intervention for both groups is conducted in 90 to 120-minute group sessions. The primary outcome of the study would be a decrease in psychopathology severity, an improvement in participants' quality of life, and reduction in family burden will be followed for 6 months. Discussion: This paper presents a protocol for a randomized controlled trial of independent and social living skills training intervention delivered to participants with schizophrenia. If this intervention is effective, it could be scaled up to be developing for policymaking and improving outcomes for schizophrenic participants and their families in Iran
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