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Jingjie Yeo's picture

Free-standing graphene slit membrane for enhanced desalination

http://dx.doi.org/10.1016/j.carbon.2016.09.043 This study considers two novel ideas to further explore and enhance the graphene membrane for desalination. Firstly, while earlier molecular dynamics (MD) simulations studies have used frozen membranes, free-standing membrane is considered here. Since 2D membranes are usually embedded on porous support in the experimental reverse osmosis (RO) process, the free-standing membrane can more accurately model the behavior expected during operation.

Antonino Favata's picture

Graphene is softer to bend when stretched and bent and harder to stretch when bent and moderately stretched

 

In the attached paper, we have shown that concomitant bending and stretching, whatever their value, concur to make bending stiffness decrease; moreover, concomitant bending and stretching make the stretching stiffness (or the Young modulus) increase until the applied forces reach a threshold value, then they make it decrease. Said differently, graphene is softer to bend when stretched and bent and harder to stretch when bent and moderately stretched.

 

Antonino Favata's picture

An analytical benchmark for MD codes: testing and correcting LAMMPS

In the attached paper, recently appeared on Computer Physics Communications, we have proposed an analytical benchmark and a simple consistent Mathematica program for graphene and carbon nanotubes, that may serve to test any molecular dynamics code implemented with REBO potentials. By exploiting the benchmark, we checked results produced by LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) when adopting the second generation Brenner potential, we made evident that this code in its current implementation produces results which are offset from those of the benchmark by a significant amount, and provided evidence of the reason.

Harley T. Johnson's picture

A critical thickness condition for graphene and other 2D materials

B. C. McGuigan, P. Pochet, and H. T. Johnson, Critical thickness for interface misfit dislocation formation in two-dimensional materials, Phys. Rev. B 93, 214103, 2016.

URL: http://link.aps.org/doi/10.1103/PhysRevB.93.214103

Harold S. Park's picture

Journal Club Theme of June 2016: 2D Materials: Current and Future Directions

Two-Dimensional (2D) materials have been widely studied since the discovery of graphene in 2004.  Many of the initial works on the various 2D materials (graphene, MoS2 and other transition metal dichalcogenides, black phosphorus, and others like the monochalcogenides) by mechanicians focused on issues like ideal strength, and appropriate methods to calculate the bending modulus.  Some of these, and other issues, were reviewed by Sulin Zhang in a J-Club from March 2015 (http://imechanica

Jingjie Yeo's picture

Adsorption and Conformational Evolution of Alpha-Helical BSA Segments on Graphene: A Molecular Dynamics Study

http://dx.doi.org/10.1142/S1758825116500216 Molecular dynamics (MD) simulations are performed to investigate the adsorption mechanics and conformational dynamics of single and multiple bovine serum albumin (BSA) peptide segments on single-layer graphene through analysis of parameters such as the root-mean-square displacements, number of hydrogen bonds, helical content, inter- action energies, and motions of mass center of the peptides.

Harold S. Park's picture

Negative Poisson's Ratio in Single-Layer Graphene Ribbons

The Poisson's ratio characterizes the resultant strain in the lateral direction for a material under longitudinal deformation.  Though negative Poisson's ratios (NPR) are theoretically possible within continuum elasticity, they are most frequently observed in engineered materials and structures, as they are not intrinsic to many materials.  In this work, we report NPR in single-layer graphene ribbons, which results from the compressive edge stress induced warping of the edges.

Antonino Favata's picture

Graphene and Carbon Nanotubes are self-stressed

In the attached paper we have shown that graphene and carbon nanotubes are in a self-stress state in their natural equilibrium state, that is, the state prior to the application of external loads. We have identified different sources of self-stresses and accurately evaluated them; we have shown that they are by no means negligible with respect to load-related nanostresses.

Jingjie Yeo's picture

Peptide–Graphene Interactions Enhance the Mechanical Properties of Silk Fibroin

http://pubs.acs.org/doi/abs/10.1021/acsami.5b05615 Studies reveal that biomolecules can form intriguing molecular structures with fascinating functionalities upon interaction with graphene. Then, interesting questions arise. How does silk fibroin interact with graphene? Does such interaction lead to an enhancement in its mechanical properties?

Shuze Zhu's picture

Pseudomagnetic Fields in a Locally Strained Graphene Drumhead

Recent experiments reveal that a scanning tunneling microscopy (STM) probe tip can generate a highly localized strain field in a graphene drumhead, which in turn leads to pseudomagnetic fields in the graphene that can spatially confine graphene charge carriers in a way similar to a lithographically defined quantum dot (QD). While these experimental findings are intriguing, their further implementation in nanoelectronic devices hinges upon the knowledge of key underpinning parameters, which still remain elusive.

rrahman's picture

Deformation mechanism of graphene in amorphous polyethylene: A molecular dynamics based study

The current paper focuses on investigating deformation mechanism of graphene sheets in a graphene reinforced polyethylene (Gn–PE) nanocomposite. Classical molecular dynamics (MD) simulation was conducted on large Gn–PE systems. Different spatial arrangements of graphene sheets were considered in order to study the effect of nonlocal interaction among the graphenes. In all the cases 5% weight concentration of graphene was considered in order to prepare atomistic models for Gn–PE.

Teng Li's picture

Hydrogenation-Assisted Graphene Origami (HAGO)

Hydrogenation-Assisted Graphene Origami and Its Application in Programmable Molecular Mass Uptake, Storage, and Release 

Shuze Zhu and Teng Li, ACS Nano, 8 (3), pp 2864–2872 (2014)

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