Traction Separation Laws of Hydrogenated Grain Boundaries of Graphene

2020 ◽  
Author(s):  
Mohan S. R. Elapolu ◽  
Alireza Tabarraei
Keyword(s):  
Fracture Toughness ◽  
Grain Boundaries ◽  
Molecular Dynamic ◽  
Hydrogen Concentration ◽  
Hydrogen Adsorption ◽  
Hydrogen Atoms ◽  
Dynamic Simulations ◽  
Wales Defect ◽  
Before And After ◽  
Two Factors

Abstract Molecular dynamic simulations are conducted to understand the fracture properties of bicrystalline graphene sheets containing high angle grain boundaries. In our simulations, hydrogen atoms are adsorbed at the Stone–Wales defect on the grain boundaries. Hydrogenation of these defects alters the properties of grain boundaries. Using molecular dynamic modeling, the traction-separation laws of grain boundaries before and after hydrogenation are extracted. Our results show that the hydrogen adsorption site and hydrogen concentration are two factors which can significantly impact fracture toughness and strength of grain boundaries. Generally speaking, by increase in hydrogen concentration at the grain boundaries the fracture toughness and strength of the grain boundaries are reduced.

Spotting Differences in Molecular Dynamic Simulations of Influenza A M2 Protein-Ligand Complexes by Varying M2 construct, Lipid Bilayer and Force Field

2019 ◽  
Author(s):  
Dimitrios Kolokouris ◽  
Iris Kalenderoglou ◽  
Panagiotis Lagarias ◽  
Antonios Kolocouris
Keyword(s):  
Molecular Dynamic ◽  
Lipid Bilayer ◽  
Influenza A ◽  
Md Simulations ◽  
Membrane Curvature ◽  
Buffer Size ◽  
M2 Protein ◽  
Dynamic Simulations ◽  
Amphipathic Helices ◽  
Drug Protein Binding

<p>We studied by molecular dynamic (MD) simulations systems including the inward<sub>closed</sub> state of influenza A M2 protein in complex with aminoadamantane drugs in membrane bilayers. We varied the M2 construct and performed MD simulations in M2TM or M2TM with amphipathic helices (M2AH). We also varied the lipid bilayer by changing either the lipid, DMPC or POPC, POPE or POPC/cholesterol (chol), or the lipids buffer size, 10x10 Å<sup>2 </sup>or 20x20 Å<sup>2</sup>. We aimed to suggest optimal system conditions for the computational description of this ion channel and related systems. Measures performed include quantities that are available experimentally and include: (a) the position of ligand, waters and chlorine anion inside the M2 pore, (b) the passage of waters from the outward Val27 gate of M2 S31N in complex with an aminoadamantane-aryl head blocker, (c) M2 orientation, (d) the AHs conformation and structure which is affected from interactions with lipids and chol and is important for membrane curvature and virus budding. In several cases we tested OPLS2005, which is routinely applied to describe drug-protein binding, and CHARMM36 which describes reliably protein conformation. We found that for the description of the ligands position inside the M2 pore, a 10x10 Å<sup>2</sup> lipids buffer in DMPC is needed when M2TM is used but 20x20 Å<sup>2</sup> lipids buffer of the softer POPC; when M2AH is used all 10x10 Å<sup>2</sup> lipid buffers with any of the tested lipids can be used. For the passage of waters at least M2AH with a 10x10 Å<sup>2</sup> lipid buffer is needed. The folding conformation of AHs which is defined from hydrogen bonding interactions with the bilayer and the complex with chol is described well with a 10x10 Å<sup>2</sup> lipids buffer and CHARMM36. </p>

Control of hydrogen absorption by nickel films obtained upon magnetic spraying of zirconium alloy using the thermoEMF method

2020 ◽  
Vol 86 (8) ◽  
pp. 32-37
Author(s):  
V. V. Larionov ◽  
Xu Shupeng ◽  
V. N. Kudiyarov
Keyword(s):  
Magnetron Sputtering ◽  
Hydrogen Concentration ◽  
Hydrogen Absorption ◽  
Zirconium Alloy ◽  
Hydrogen Adsorption ◽  
Zirconium Alloys ◽  
Nickel Film ◽  
Protective Film ◽  
Nickel Films ◽  
Hydrogen Penetration

Nickel films formed on the surface of zirconium alloys are often used to protect materials against hydrogen penetration. Hydrogen adsorption on nickel is faster since the latter actively interacts with hydrogen, oxidizes and forms a protective film. The goal of the study is to develop a method providing control of hydrogen absorption by nickel films during vacuum-magnetron sputtering and hydrogenation via measuring thermoEMF. Zirconium alloy E110 was saturated from the gas phase with hydrogen at a temperature of 350°C and a pressure of 2 atm. A specialized Rainbow Spectrum unit was used for coating. It is shown that a nickel film present on the surface significantly affects the hydrogen penetration into the alloy. A coating with a thickness of more than 2 μm deposited by magnetron sputtering on the surface of a zirconium alloy with 1% Nb, almost completely protects the alloy against hydrogen penetration. The magnitude of thermoemf depends on the hydrogen concentration in the zirconium alloy and film thickness. An analysis of the hysteresis width of the thermoEMF temperature loop and a method for determining the effective activation energy of the conductivity of a hydrogenated material coated with a nickel film are presented. The results of the study can be used in assessing the hydrogen concentration and, hence, corrosion protection of the material.

scholarly journals Ranking the Efficiency of Gas Hydrate Anti-agglomerants through Molecular Dynamic Simulations

2021 ◽  
Vol 125 (5) ◽  
pp. 1487-1502
Author(s):  
Stephan Mohr ◽  
Felix Hoevelmann ◽  
Jonathan Wylde ◽  
Natascha Schelero ◽  
Juan Sarria ◽  
...  
Keyword(s):  
Molecular Dynamic ◽  
Gas Hydrate ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations

Construction of a coal char model and its combustion and gasification characteristics: Molecular dynamic simulations based on ReaxFF

Fuel ◽  
2021 ◽  
Vol 300 ◽  
pp. 120972
Author(s):  
Dikun Hong ◽  
Liang Liu ◽  
Chunbo Wang ◽  
Ting Si ◽  
Xin Guo
Keyword(s):  
Molecular Dynamic ◽  
Coal Char ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations

Effect of interlayer cations on montmorillonite swelling: Comparison between molecular dynamic simulations and experiments

2021 ◽  
Vol 204 ◽  
pp. 106034
Author(s):  
Kenji Yotsuji ◽  
Yukio Tachi ◽  
Hiroshi Sakuma ◽  
Katsuyuki Kawamura
Keyword(s):  
Molecular Dynamic ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Interlayer Cations

scholarly journals Flow of long chain hydrocarbons through carbon nanotubes (CNTs)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pranay Asai ◽  
Palash Panja ◽  
Raul Velasco ◽  
Milind Deo
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamic ◽  
Continuum Models ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Pharmaceutical Applications ◽  
Molecular Sizes ◽  
Hydrocarbon Molecules ◽  
Pressure Driven Flow ◽  
Long Chain

AbstractThe pressure-driven flow of long-chain hydrocarbons in nanosized pores is important in energy, environmental, biological, and pharmaceutical applications. This paper examines the flow of hexane, heptane, and decane in carbon nanotubes (CNTs) of pore diameters 1–8 nm using molecular dynamic simulations. Enhancement of water flow in CNTs in comparison to rates predicted by continuum models has been well established in the literature. Our work was intended to observe if molecular dynamic simulations of hydrocarbon flow in CNTs produced similar enhancements. We used the OPLS-AA force field to simulate the hydrocarbons and the CNTs. Our simulations predicted the bulk densities of the hydrocarbons to be within 3% of the literature values. Molecular sizes and shapes of the hydrocarbon molecules compared to the pore size create interesting density patterns for smaller sized CNTs. We observed moderate flow enhancements for all the hydrocarbons (1–100) flowing through small-sized CNTs. For very small CNTs the larger hydrocarbons were forced to flow in a cork-screw fashion. As a result of this flow orientation, the larger molecules flowed as effectively (similar enhancements) as the smaller hydrocarbons.

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