arXiv subjects

J. Breton

Publications and source records attributed to J. Breton.

3 recordsLinked to original sources

arXiv2013

A minimal representation of the self-assembly of virus capsids

Viruses are biological nanosystems with a capsid of protein-made capsomer units that encloses and protects the genetic material responsible for their replication. Here we show how the geometrical constraints of the capsomer-capsomer interaction in icosahedral capsids fix the form of the shortest and universal truncated multipolar expansion of the two-body interaction between capsomers. The structures of many of the icosahedral and related virus capsids are located as single lowest energy states of this potential energy surface. Our approach unveils relevant features of the natural design of the capsids and can be of interest in fields of nanoscience and nanotechnology where similar hollow convex structures are relevant.

physics.bio-ph↗

arXiv2009

Towards a quantum approach to cell membrane electrodynamics

The ultimate active constituents of the living medium, membranes, ions and molecules, are at the level of the nanometer. Their interactions thus require a quantum processing. The characteristic Action A, linked to the "quantum objects" : ions, radicals, water molecule... of the living medium, has an average value of A ~= 14.10-34 J.s or A ~= 2 h . It is thus strictly impossible to formulate a realistic "classical " theory of membrane electrodynamics. The transfer of the sodium ion - among others - could be then ensured under the action of a Tunnel effect, (with Hartman?s mechanism) specific to the channel and the ion transferred.

physics.bio-ph↗

arXiv2007

Global Potential Energy Minima of (H$_{2}$O)$_{n}$ Clusters on Graphite

Likely candidates for the global potential energy minima of (H$_{2}$O)$_{n}$ clusters with $n\leq21$ on the (0001)-surface of graphite are found using basin-hopping global optimization. The potential energy surfaces are constructed using the TIP4P intermolecular potentials for the water molecules (the TIP3P is also explored as a secondary choice), a Lennard-Jones water-graphite potential, and a water-graphite polarization potential that is built from classical electrostatic image methods and takes into account both the perpendicular and parallel electric polarizations of graphite. This potential energy surface produces a rather hydrophobic water-graphite interaction. As a consequence, the water component of the lowest graphite-(H$_{2}$O)$_{n}$ minima is quite closely related to low-lying minima of the corresponding TIP4P (H$_{2}$O)$_{n}$ clusters. In about half of the cases the geometrical substructure of the water molecules in the graphite-(H$_{2}$O)$_{n}$ global minimum coincides with that of the corresponding free water cluster. Exceptions occur when the interaction with graphite induces a change in geometry. A comparison of our results with available theoretical and experimental data is performed.

physics.atm-clus↗