Water diffusion in carbon nanotubes under directional electric fields: Coupling between mobility and hydrogen bonding

Competition between hydrogen bonding and electric field in single-file transport of water in carbon nanotubes

Recent studies have shown the possibility of water transport across carbon nanotubes, even in the case of nanotubes with small diameter (0.822 nm). In this case, water shows subcontinuum transport following an ordered 1D structure stabilized by hydrogen bonds. In this work, we report MD simulations describing the effect of a perpendicular electric field in this single-file water transport in carbon nanotubes. We show that water permeation is substantially reduced for field intensities of 2-3 V/nm and it is no longer possible under perpendicular fields of 4 V/nm.

碳纳米管中肽构象动力学对定向机械力的敏感性

Sensitivity of peptide conformational dynamics in carbon nanotubes to directional mechanical forces

本研究通过力探针分子动力学模拟，探究碳纳米管受限环境中定向拉/推十肽对其构象动力学的影响，发现力加载速率和肽序列的作用更显著，拉动肽的穿管过程更顺畅，为理解细胞内短肽受限空间穿行机制提供了依据。

High-Tc superconductivity in entirely end-bonded multi-walled carbon nanotubes

We report that entirely end-bonded multi-walled carbon nanotubes (MWNTs) can show superconductivity with the transition temperature Tc as high as 12K that is approximately 40-times larger than those reported in ropes of single-walled nanotubes. We find that emergence of this superconductivity is very sensitive to junction structures of Au electrode/MWNTs. This reveals that only MWNTs with optimal numbers of electrically activated shells, which are realized by the end-bonding, can allow the superconductivity due to inter shell effects.

Carbon nanotube plectonemes: Loops of twisted helices

The relaxation of twist in elastic filaments often drives conformational changes. We explore this paradigm using all-atom computations and report the formation of novel supercoiled shapes in individual carbon nanotubes (CNTs). Decreasing the end distance of torsionally constrained CNTs leads to spontaneous nucleation and growth of a nanotube plectoneme. We develop a stability diagram and comparisons with theoretical frameworks reveal the importance of non-local van Der Waals interactions. In some cases, they stabilize the supercoiling to an extent that its tip locally kinks and then irreversib…

Topological connection between vesicles and nanotubes in single-molecule lipid membranes driven by head-tail interactions

Lipid nanotube-vesicle networks are important channels for intercellular communication and transport of matter. Experimentally observed in neighboring mammalian cells, but also reproduced in model membrane systems, a broad consensus exists on their formation and stability. Lipid membranes must be composed of at least two molecular components, each stabilizing low (generally a phospholipid) and high curvatures. Strong anisotropy or enhanced conical shape of the second amphiphile is crucial for the formation of nanotunnels. Anisotropic driving forces generally favor nanotube protrusions from ves…

LAMMPS Framework for Dynamic Bonding and an Application Modeling DNA

We have extended the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to support directional bonds and dynamic bonding. The framework supports stochastic formation of new bonds, breakage of existing bonds, and conversion between bond types. Bond formation can be controlled to limit the maximal functionality of a bead with respect to various bond types. Concomitant with the bond dynamics, angular and dihedral interactions are dynamically introduced between newly connected triplets and quartets of beads, where the interaction type is determined from the local pattern of bead an…