3,099 research outputs found
Hard discs under steady shear: comparison of Brownian dynamics simulations and mode coupling theory
Brownian dynamics simulations of bidisperse hard discs moving in two
dimensions in a given steady and homogeneous shear flow are presented close to
and above the glasstransition density. The stationary structure functions and
stresses of shear-melted glass are compared quantitatively to parameter-free
numerical calculations of monodisperse hard discs using mode coupling theory
within the integration through transients framework. Theory qualitatively
explains the properties of the yielding glass but quantitatively
overestimatesthe shear-driven stresses and structural anisotropies.Comment: 1. The original Phil. Trans. R. Soc. contains an error in the caption
of the y-axes of the upper left panel in figure 9: There's a factor
\dot{\gamma} missing in the denominato
Theoretical Study of Corundum as an Ideal Gate Dielectric Material for Graphene Transistors
Using physical insights and advanced first-principles calculations, we
suggest that corundum is an ideal gate dielectric material for graphene
transistors. Clean interface exists between graphene and Al-terminated (or
hydroxylated) Al2O3 and the valence band offsets for these systems are large
enough to create injection barrier. Remarkably, a band gap of {\guillemotright}
180 meV can be induced in graphene layer adsorbed on Al-terminated surface,
which could realize large ON/OFF ratio and high carrier mobility in graphene
transistors without additional band gap engineering and significant reduction
of transport properties. Moreover, the band gaps of graphene/Al2O3 system could
be tuned by an external electric field for practical applications
Thermodynamics of Blue Phases In Electric Fields
We present extensive numerical studies to determine the phase diagrams of
cubic and hexagonal blue phases in an electric field. We confirm the earlier
prediction that hexagonal phases, both 2 and 3 dimensional, are stabilized by a
field, but we significantly refine the phase boundaries, which were previously
estimated by means of a semi-analytical approximation. In particular, our
simulations show that the blue phase I -- blue phase II transition at fixed
chirality is largely unaffected by electric field, as observed experimentally.Comment: submitted to Physical Review E, 7 pages (excluding figures), 12
figure
Rheology of Lamellar Liquid Crystals in Two and Three Dimensions: A Simulation Study
We present large scale computer simulations of the nonlinear bulk rheology of
lamellar phases (smectic liquid crystals) at moderate to large values of the
shear rate (Peclet numbers 10-100), in both two and three dimensions. In two
dimensions we find that modest shear rates align the system and stabilise an
almost regular lamellar phase, but high shear rates induce the nucleation and
proliferation of defects, which in steady state is balanced by the annihilation
of defects of opposite sign. The critical shear rate at onset of this second
regime is controlled by thermodynamic and kinetic parameters; we offer a
scaling analysis that relates the critical shear rate to a critical "capillary
number" involving those variables. Within the defect proliferation regime, the
defects may be partially annealed by slowly decreasing the applied shear rate;
this causes marked memory effects, and history-dependent rheology. Simulations
in three dimensions show instead shear-induced ordering even at the highest
shear rates studied here. This suggests that the critical shear rate shifts
markedly upward on increasing dimensionality. This may in part reflect the
reduced constraints on defect motion, allowing them to find and annihilate each
other more easily. Residual edge defects in the 3D aligned state mostly point
along the flow velocity, an orientation impossible in two dimensions.Comment: 18 pages, 12 figure
Sensitization of renal carcinoma cells to TRAIL-induced apoptosis by rocaglamide and analogs
Rocaglamide has been reported to sensitize several cell types to TRAIL-induced apoptosis. In recent years, advances in synthetic techniques have led to generation of novel rocaglamide analogs. However, these have not been extensively analyzed as TRAIL sensitizers, particularly in TRAIL-resistant renal cell carcinoma cells. Evaluation of rocaglamide and analogs identified 29 compounds that are able to sensitize TRAIL-resistant ACHN cells to TRAIL-induced, caspase-dependent apoptosis with sub-µM potency which correlated with their potency as protein synthesis inhibitors and with loss of cFLIP protein in the same cells. Rocaglamide alone induced cell cycle arrest, but not apoptosis. Rocaglates averaged 4–5-fold higher potency as TRAIL sensitizers than as protein synthesis inhibitors suggesting a potential window for maximizing TRAIL sensitization while minimizing effects of general protein synthesis inhibition. A wide range of other rocaglate effects (e.g. on JNK or RAF-MEK-ERK signaling, death receptor levels, ROS, ER stress, eIF4E phosphorylation) were assessed, but did not contribute to TRAIL sensitization. Other than a rapid loss of MCL-1, rocaglates had minimal effects on mitochondrial apoptotic pathway proteins. The identification of structurally diverse/mechanistically similar TRAIL sensitizing rocaglates provides insights into both rocaglate structure and function and potential further development for use in RCC-directed combination therapy.This project has been funded in whole or in part with Federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261200800001E. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government. This research was supported [in part] by the Intramural Research Program of NIH, Frederick. National Lab, Center for Cancer Research. Research performed at Boston University was supported in part by NIH R35 GM118173. Work at the BU-CMD is supported by R24 GM111625. (HHSN261200800001E - National Cancer Institute, National Institutes of Health; Intramural Research Program of NIH, Frederick. National Lab, Center for Cancer Research; R35 GM118173 - NIH; R24 GM111625)Published versio
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