3,918 research outputs found
Thermal transport in nanocrystalline graphene investigated by approach-to-equilibrium molecular dynamics simulations
Approach-to-equilibrium molecular dynamics simulations have been used to
study thermal transport in nanocrystalline graphene sheets. Nanostructured
graphene has been created using an iterative process for grain growth from
initial seeds with random crystallographic orientations. The resulting cells
have been characterized by the grain size distribution based on the radius of
gyration, by the number of atoms in each grain and by the number of atoms in
the grain boundary. Introduction of nanograins with a radius of gyration of 1
nm has led to a significant reduction in the thermal conductivity to 3% of the
value in single crystalline graphene. Analysis of the vibrational density of
states has revealed a general reduction of the vibrational intensities and
broadening of the peaks when nanograins are introduced which can be attributed
to phonon scattering in the boundary layer. The thermal conductivity has been
evaluated as a function of the grain size with increasing size up to 14 nm and
it has been shown to follow an inverse rational function. The grain size
dependent thermal conductivity could be approximated well by a function where
transport is described by a connection in series of conducting elements and
resistances (at boundaries).Comment: 9 pages, 9 figure
Oxytocin nasal spray in fibromyalgic patients: additional information : reply to the comment to the editor entitled "future directions for the investigation of intranasal oxytocin and pain"
Analysis of acid-stressed Bacillus cereus reveals a major oxidative response and inactivation-associated radical formation
Acid stress resistance of the food-borne human pathogen Bacillus cereus may contribute to its survival in acidic environments, such as encountered in soil, food and the human gastrointestinal tract. The acid stress responses of B. cereus strains ATCC 14579 and ATCC 10987 were analysed in aerobically grown cultures acidified to pH values ranging from pH 5.4 to pH 4.4 with HCI. Comparative phenotype and transcriptome analyses revealed three acid stressinduced responses in this pH range: growth rate reduction, growth arrest and loss of viability. These physiological responses showed to be associated with metabolic shifts and the induction of general stress response mechanisms with a major oxidative component, including upregulation of catalases and superoxide dismutases. Flow cytometry analysis in combination with the hydroxyl (OH center dot) and peroxynitrite (ONOO-)-specific fluorescent probe 3'-(phydroxyphenyl) fluorescein (HPF) showed excessive radicals to be formed in both B. cereus strains in bactericidal conditions only. Our study shows that radicals can indicate acid-induced malfunctioning of cellular processes that lead to cell death
Genetic sensitivity to the bitter taste of 6-n-propylthiouracil (PROP) and its association with Physiological mechanisms controlling Body Mass Index (BMI)
Taste sensitivity to the bitter compound 6-n-propylthiouracil (PROP) is considered a marker for individual differences in taste perception that may influence food preferences and eating behavior, and thereby energy metabolism. This review describes genetic factors that may contribute to PROP sensitivity including: (1) the variants of the TAS2R38 bitter receptor with their different affinities for the stimulus; (2) the gene that controls the gustin protein that acts as a salivary trophic factor for fungiform taste papillae; and (3) other specific salivary proteins that could be involved in facilitating the binding of the PROP molecule with its receptor. In addition, we speculate on the influence of taste sensitivity on energy metabolism, possibly via modulation of the endocannabinoid system, and its possible role in regulating body composition homeostasis
Finite element elastic-plastic-creep and cyclic life analysis of a cowl lip
Results are presented of elastic, elastic-plastic, and elastic-plastic-creep analyses of a test-rig component of an actively cooled cowl lip. A cowl lip is part of the leading edge of an engine inlet of proposed hypersonic aircraft and is subject to severe thermal loadings and gradients during flight. Values of stresses calculated by elastic analysis are well above the yield strength of the cowl lip material. Such values are highly unrealistic, and thus elastic stress analyses are inappropriate. The inelastic (elastic-plastic and elastic-plastic-creep) analyses produce more reasonable and acceptable stress and strain distributions in the component. Finally, using the results from these analyses, predictions are made for the cyclic crack initiation life of a cowl lip. A comparison of predicted cyclic lives shows the cyclic life prediction from the elastic-plastic-creep analysis to be the lowest and, hence, most realistic
Chloroplast Response in Dunaliella salina to Irradiance Stress (Effect on Thylakoid Membrane Protein Assembly and Function)
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