Directed motion of C60 on a graphene sheet subjected to a temperature gradient

Nonequilibrium molecular dynamics simulations is used to study the motion of a C60 molecule on a graphene sheet subjected to a temperature gradient. The C60 molecule is actuated and moves along the system while it just randomly dances along the perpendicular direction. Increasing the temperature gradient increases the directed velocity of C60. It is found that the free energy decreases as the C60 molecule moves toward the cold end. The driving mechanism based on the temperature gradient suggests the construction of nanoscale graphene-based motors

Fast water flow through graphene nanocapillaries: a continuum model approach involving the microscopic structure of confined water

Water inside a nanocapillary becomes ordered, resulting in unconventional behavior. A profound enhancement of water flow inside nanometer thin capillaries made of graphene has been observed [B. Radha et.al., Nature (London) 538, 222 (2016)]. Here we explain this enhancement as due to the large density and the extraordinary viscosity of water inside the graphene nanocapillaries. Using the Hagen-Poiseuille theory with slippage-boundary condition and incorporating disjoining pressure term in combination with results from molecular dynamics (MD) simulations, we present an analytical theory that elucidates the origin of the enhancement of water flow inside hydrophobic nanocapillaries. Our work reveals a distinctive dependence of water flow in a nanocapillary on the structural properties of nanoconfined water in agreement with experiment, which opens a new avenue in nanofluidics.Comment: 5 pages, 4 Figure

Modeling the effect of a electric field on the dynamics of calcium ions in calcium ion channel

Calcium channels are cell membrane proteins that play an important role in control the Ca ion flux through the membrane. In this study, the effect of external constant electric field on the dynamics of calcium ions in a L-type channel, located within a stochastically fluctuating medium, is modeled via the application of the molecular dynamics (MD) simulation method. The obtained results show that application of constant field of 0.03 V/nm did not show significant effect on the ions motion. On the other hand, when the channel is exposed to a constant electric field of strength 0.3 V/nm, the ions directional motion along the applied field is observed. Furthermore, it is found that no net motion is observed when the field direction is changed

The effects of temperature and vacancies on dynamics of crack in graphene sheet

Crack propagation in a defected graphene sheet is investigated at finite temperature using molecular dynamics simulation. The effects of several initial cracks, temperature and different percentage of vacancies are considered. It is found that i) the critical load, which is a criteria for crack propagation, is larger when the load is applied on the zigzag direction, ii) the critical load decreases with increasing temperature, iii) a hole in the center of the sheet and the presence of randomly distributed vacancies reduce the critical load giving different crack propagation trajectory. Our new results would help to understand the crack propagation phenomena in defected graphene at finite temperature