THE STUDY ON THE GAS PERMEABILITIES OF THE ETHYLENE/1-HEXENE COPOLYMER BY MOLECULAR DYNAMICS SIMULATION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5859-5864 ◽  
Author(s):  
SIZHU WU ◽  
JUN YI ◽  
LISHU ZHANG ◽  
LIQUN ZHANG ◽  
JAMES E. MARK
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Atomistic Simulation ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Simulation Studies ◽  
Molecular Potentials ◽  
Gas Molecules ◽  
Poly Ethylene ◽  
Diffusion Coefficient Of Oxygen

In this research, molecular dynamics(MD) simulations were used to study the transport properties of small gas molecules in poly(ethylene-co-1-hexene) copolymer. The condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) forcefield was applied. The diffusion coefficients were obtained from MD (NVT ensemble). The results indicated that the diffusion coefficient of oxygen increased with increasing 1-hexene content in copolymer membrane.

Molecular Dynamics Simulation of Molten Alkali Nitrates

2001 ◽  
Vol 56 (5) ◽  
pp. 337-341 ◽  
Author(s):  
G. Vöhringer ◽  
J. Richter
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Short Range ◽  
Spin Echo ◽  
Isotope Effects ◽  
Pair Potential ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Self Diffusion ◽  
Transport Effects

Abstract Molecular dynamics (MD) simulations have been performed for several pure alkali nitrate melts. Special attention was paid to the examination of the interaction potential: macroscopic quantities like pressure were calculated and compared with real values. To improve the results the commonly used potential for alkali nitrates (Coulomb pair potential and Born-type repulsion) has been extended by a short-range-attraction term to meet the real behaviour of the liquid. With these improved potentials, simulations of pure LiNO3, NaNO3, KNO3, and RbNO3 have been performed with special regard to the influence of size and mass of the cations on the transport effects to show analogies to isotope effects. The calculated self diffusion coefficients (SDC) have been compared to results obtained with the NMR spin echo method.

Molecular dynamics simulation on the interfacial features of supercritical 1-butene/subcritical water

2014 ◽  
Vol 13 (08) ◽  
pp. 1450066 ◽  
Author(s):  
Huidong Zheng ◽  
Jingjing Chen ◽  
Fangdi Wu ◽  
Suying Zhao
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Subcritical Water ◽  
Md Simulations ◽  
Extraction Process ◽  
Supercritical Condition ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Butanol Concentration ◽  
Subcritical Condition

We studied the interfacial features of 1-butene/water and extraction process of 2-butanol by molecular dynamics (MD) simulations. The infinite dilute diffusion coefficients of 1-butene in water is larger than that of 2-butanol, and one important reason is that 2-butanol molecules can form hydrogen bonds with water molecules. 1-butene is more soluble in water under supercritical condition than that under subcritical condition. 1-butene under supercritical condition can extract more 2-butanol from aqueous solution than that under other conditions. A process of producing 2-butanol by the direct hydration of 1-butene is more competive when it operates under the supercritical conditions of 1-butene which due to a higher solubility of 1-butene in water, a larger diffusion coefficient of 1-butene and a lower 2-butanol concentration in water.

Molecular dynamics simulation studies of binary blend miscibility of poly(3-hydroxybutyrate) and poly(ethylene oxide)

Polymer ◽  
2004 ◽  
Vol 45 (2) ◽  
pp. 453-457 ◽  
Author(s):  
Hua Yang ◽  
Li Ze-Sheng ◽  
Hu-jun Qian ◽  
Yong-biao Yang ◽  
Xiu-bin Zhang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ethylene Oxide ◽  
Dynamics Simulation ◽  
Simulation Studies ◽  
Binary Blend ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

scholarly journals Computational Investigations on the Binding Mode of Ligands for the Cannabinoid-Activated G Protein-Coupled Receptor GPR18

Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 686 ◽  
Author(s):  
Alexander Neumann ◽  
Viktor Engel ◽  
Andhika B. Mahardhika ◽  
Clara T. Schoeder ◽  
Vigneshwaran Namasivayam ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
G Protein ◽  
Phenyl Ring ◽  
Binding Mode ◽  
Dynamics Simulation ◽  
Simulation Studies ◽  
Binding Modes ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

GPR18 is an orphan G protein-coupled receptor (GPCR) expressed in cells of the immune system. It is activated by the cannabinoid receptor (CB) agonist ∆9-tetrahydrocannabinol (THC). Several further lipids have been proposed to act as GPR18 agonists, but these results still require unambiguous confirmation. In the present study, we constructed a homology model of the human GPR18 based on an ensemble of three GPCR crystal structures to investigate the binding modes of the agonist THC and the recently reported antagonists which feature an imidazothiazinone core to which a (substituted) phenyl ring is connected via a lipophilic linker. Docking and molecular dynamics simulation studies were performed. As a result, a hydrophobic binding pocket is predicted to accommodate the imidazothiazinone core, while the terminal phenyl ring projects towards an aromatic pocket. Hydrophobic interaction of Cys251 with substituents on the phenyl ring could explain the high potency of the most potent derivatives. Molecular dynamics simulation studies suggest that the binding of imidazothiazinone antagonists stabilizes transmembrane regions TM1, TM6 and TM7 of the receptor through a salt bridge between Asp118 and Lys133. The agonist THC is presumed to bind differently to GPR18 than to the distantly related CB receptors. This study provides insights into the binding mode of GPR18 agonists and antagonists which will facilitate future drug design for this promising potential drug target.

scholarly journals Unveiling Carbon Dioxide and Ethanol Diffusion in Carbonated Water-Ethanol Mixtures by Molecular Dynamics Simulations

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1711
Author(s):  
Mohamed Ahmed Khaireh ◽  
Marie Angot ◽  
Clara Cilindre ◽  
Gérard Liger-Belair ◽  
David A. Bonhommeau
Keyword(s):  
Carbon Dioxide ◽  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Hydrodynamic Radius ◽  
Md Simulations ◽  
Molecular Models ◽  
Experimental Values ◽  
Carbon Dioxide Co2 ◽  
Dynamics Simulations ◽  
Apparent Disagreement

The diffusion of carbon dioxide (CO2) and ethanol (EtOH) is a fundamental transport process behind the formation and growth of CO2 bubbles in sparkling beverages and the release of organoleptic compounds at the liquid free surface. In the present study, CO2 and EtOH diffusion coefficients are computed from molecular dynamics (MD) simulations and compared with experimental values derived from the Stokes-Einstein (SE) relation on the basis of viscometry experiments and hydrodynamic radii deduced from former nuclear magnetic resonance (NMR) measurements. These diffusion coefficients steadily increase with temperature and decrease as the concentration of ethanol rises. The agreement between theory and experiment is suitable for CO2. Theoretical EtOH diffusion coefficients tend to overestimate slightly experimental values, although the agreement can be improved by changing the hydrodynamic radius used to evaluate experimental diffusion coefficients. This apparent disagreement should not rely on limitations of the MD simulations nor on the approximations made to evaluate theoretical diffusion coefficients. Improvement of the molecular models, as well as additional NMR measurements on sparkling beverages at several temperatures and ethanol concentrations, would help solve this issue.

scholarly journals Understanding Covalent Grafting of Nanotubes onto Polymer Nanocomposites: Molecular Dynamics Simulation Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2621
Author(s):  
Seunghwa Yang
Keyword(s):  
Molecular Dynamics ◽  
Load Transfer ◽  
Cell Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Covalent Grafting ◽  
Modelling Strategies ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
External Loads

Here, we systematically interrogate the effects of grafting single-walled (SWNT) and multi-walled carbon nanotubes (MWNT) to polymer matrices by using molecular dynamics (MD) simulations. We specifically investigate key material properties that include interfacial load transfer, alteration of nanotube properties, and dispersion of nanotubes in the polymer matrix. Simulations are conducted on a periodic unit cell model of the nanocomposite with a straight carbon nanotube and an amorphous polyethylene terephthalate (PET) matrix. For each type of nanotube, either 0%, 1.55%, or 3.1% of the carbon atoms in the outermost nanotubes are covalently grafted onto the carbon atoms of the PET matrix. Stress-strain curves and the elastic moduli of nanotubes and nanocomposites are determined based on the density of covalent grafting. Covalent grafting promotes two rivalling effects with respect to altering nanotube properties, and improvements in interfacial load transfer in the nanocomposites are clearly observed. The enhanced interface enables external loads applied to the nanocomposites to be efficiently transferred to the grafted nanotubes. Covalent functionalization of the nanotube surface with PET molecules can alter the solubility of nanotubes and improve dispersibility. Finally, we discuss the current limitations and challenges in using molecular modelling strategies to accurately predict properties on the nanotube and polymers systems studied here.

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