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Functionalization of graphene is the best way to create a high degree of dispersion and bonding to polymer matrix in order to obtain high performance composites. The effects of carboxyl (−COOH) functionalized graphene (FG) on the mechanical properties of its epoxy-based nanocomposites have been examined by molecular dynamics (MD) simulations. Simulations cells of nanocomposites with varying wt% of FG (1, 2, and 3 wt%) were constructed using Material Studio 6.0. The MD simulation findings of nanocomposites reveal that they have better mechanical properties such as elastic modulus, bulk modulus, shear modulus, and the Poisson's ratio than pure epoxy. Furthermore, the computational results of nanocomposites have been effectively confirmed with available experimental data. Therefore, the current MD simulation shows a decent computational sign for the existing experimental and simulation outcomes on mechanical properties of FG/epoxy nanocomposites. [ABSTRACT FROM AUTHOR]

In Gram-negative bacteria, outer-membrane protein channels, such as OmpF of Escherichia coli, constitute the entry point of various classes of antibiotics. While antibacterial research and development is declining, bacterial resistance to antibiotics is rising and there is an emergency call for a new way to develop potent antibacterial agents and to bring them to the market faster and at reduced cost. An emerging strategy is to follow a bottom-up approach based on microscopically founded computational based screening, however such strategy needs better-tuned methods. Here we propose to use molecular dynamics (MD) simulations combined with the metadynamics algorithm, to study antibiotic translocation through OmpF at a molecular scale. This recently designed algorithm overcomes the time scale problem of classical MD by accelerating some reaction coordinates. It is expected that the initial assumption of the reaction coordinates is a key determinant for the efficiency and accuracy of the simulations. Previous studies using different computational schemes for a similar process only used one reaction coordinate, which is the directionality. Here we go further and see how it is possible to include more informative reaction coordinates, accounting explicitly for: (i) the antibiotic flexibility and (ii) interactions with the channel. As model systems, we select two compounds covering the main classes of antibiotics, ampicillin and moxifloxacine. We decipher the molecular mechanism of translocation of each antibiotic and highlight the important parameters that should be taken into account for improving further simulations. This will benefit the screening and design for antibiotics with better permeation properties. [ABSTRACT FROM AUTHOR]