scholarly journals Molecule Dynamics Simulation of the Effect of Oxidative Aging on Properties of Nitrile Rubber

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 226
Author(s):  
Jinsong Yang ◽  
Weitao Lou
Keyword(s):  
Free Volume ◽  
Dynamic Properties ◽  
Compressive Strain ◽  
Mean Square Displacement ◽  
Nitrile Rubber ◽  
Dynamics Simulation ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Fractional Free Volume ◽  
Oxidative Aging

The effects of oxidative aging on the static and dynamic properties of nitrile rubber at the molecular scale were investigated by molecular dynamics simulation. The aged nitrile rubber models were constructed by introducing hydroxyl groups and carbonyl groups into rubber molecular chains to mimic oxidative aging. The static and dynamic properties of the unaged and aged nitrile rubber under different conditions were evaluated by mean square displacement, self-diffusion coefficients, hydrogen bond, fractional free volume, radial distribution function, cohesive energy density and solubility parameter. The results show that the elevated temperature intensified significantly the mobility of rubber molecular chains and fractional free volume, while the compressive strain displayed the opposite effect resulting in packing and rearrangement of rubber chains. The introduction of hydroxyl groups and carbonyl groups enhanced the polarity, intermolecular interactions, the volume and rigidity of molecular chains, implying weaker mobility of molecular chains as compared to unaged models. The compressive strain and oxidative aging both decreased the fractional free volume, which inhibited gaseous and liquid diffusion into the rubber materials, and slowed down the oxidative aging rate. This study provides insights to better understand the effect of molecular changes due to oxidative aging on the structural and dynamic properties of rubber materials at the molecular level.

scholarly journals The Effect and Associate Mechanism of Nano SiO2 Particles on the Diffusion Behavior of Water in Insulating Oil

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2373 ◽  
Author(s):  
Wenxin Tian ◽  
Chao Tang ◽  
Qian Wang ◽  
Shiling Zhang ◽  
Yali Yang
Keyword(s):  
Free Volume ◽  
Breakdown Voltage ◽  
Volume Fraction ◽  
Mean Square Displacement ◽  
Nano Particles ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Nano Sio2 ◽  
Insulating Oil ◽  
Sio2 Particles

Moisture has a significant effect on the internal insulation performance of transformers, and is closely related to the breakdown voltage of transformer insulating oil. In the present work, we studied the effect of nano-SiO2 particles on the diffusion of water in insulating naphthenic mineral oil using molecular dynamics simulation. Six models were established, three of which contained nano-SiO2 particles together with water concentration of 1 wt.%, 2 wt.%, or 3 wt.%. For each model variations in free volume, mean square displacement, and interaction energy were assessed. The addition of nano SiO2 particles was found to reduce the free volume fraction of the model and as well as the free motion of water molecules in the oil. These particles also increased the interaction between the oil and water molecules, indicating that insulating oil containing nano-particles has a greater binding effect on water. The diffusion coefficient of water in oil containing nano-SiO2 particles was reduced, such that water molecules were less likely to diffuse. The results also show that these particles adsorb water molecules in the oil and to reduce diffusion. Consequently, the addition nano-scale SiO2 particles could potentially improve the breakdown voltage of the insulating oil.

scholarly journals Structural and Dynamic Properties of Hydrophobic Eutectic Solvents Based on Menthol and Fatty Acids: a Molecular Dynamics Simulation Study

2021 ◽  
Author(s):  
Samaneh Barani Pour ◽  
Jaber Jahanbin Sardroodi ◽  
Alireza Rastkar Ebrahimzadeh
Keyword(s):  
Molecular Dynamics ◽  
Fatty Acids ◽  
Dynamic Properties ◽  
Mean Square Displacement ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Eutectic Mixtures ◽  
Dynamical Properties ◽  
Reorientation Dynamics ◽  
Dynamics Simulations

Abstract The structural and dynamical properties of the binary mixture of Menthol (MEN) and Fatty acids (FAs) were investigated using molecular dynamics simulations. We focused on the relationship between the structural and dynamical properties of the eutectic mixtures of MEN and FAs with different molar percentages of FAs. Structural properties of the eutectic mixtures were characterized by calculating the combined distribution functions(CDFs), the radial distribution functions (RDFs), and the angular distribution functions (ADFs), and the Hydrogen bonding network between species and Spatial distribution functions (SDF). Further interaction between menthol and Caprylic acid molecules was confirmed by the results of these analyzes. Also, the transport properties of the mixtures were investigated by using the mean square displacement (MSD) of the centers of mass of the species, self-diffusion coefficients and vector reorientation dynamics (VRD) of bonds. The simulation results indicated that intermolecular interactions have a significant effect on the dynamic properties of species.

scholarly journals Mechanical and Tribological Properties of Nitrile Rubber Reinforced by SiO2: Molecular Dynamics Simulation  Mechanical and Tribological Properties of Nitrile Rubber Reinforced by SiO2: Molecular Dynamics Simulation

2021 ◽  
Author(s):  
Xueshen Liu ◽  
Xincong Zhou ◽  
Fuming Kuang ◽  
Houxiu Zuo ◽  
Jian Huang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Tribological Properties ◽  
Friction Stress ◽  
Nitrile Rubber ◽  
Dynamics Simulation ◽  
Radius Of Gyration ◽  
Fractional Free Volume ◽  
Mechanical And Tribological Properties ◽  
Molecular Scale

Abstract This paper investigated the mechanism of enhancing the mechanical and tribological properties of nitrile rubber (NBR) with SiO 2 on the molecular scale. Molecular dynamics (MD) simulations were performed on molecular structure models of pure NBR, NBR/SiO 2 and three-layer friction pairs. The results showed that the hydrogen bonds and interfacial interaction between SiO 2 and NBR molecular chains decreased the fractional free volume of NBR nanocomposites, and increased the shear modulus of NBR by 25% compared with that of pure NBR. During the friction process, SiO 2 decreased the radius of gyration of NBR molecular chains and effectively lowered the peak atomic velocity, the peak temperature and the peak friction stress at the interface between NBR and copper atoms. The average friction stress on NBR/SiO 2 was 34% lower than that on NBR, which meant the tribological properties of NBR were significantly improved by SiO 2 . The mechanism of SiO 2 reinforcing NBR on a molecular scale can lay a theoretical foundation for the design of water-lubricated rubber bearings.

QM/MM Simulations of Organic Phosphorus Adsorption at the Diaspore-Water Interface

2019 ◽  
Author(s):  
Prasanth Babu Ganta ◽  
Oliver Kühn ◽  
Ashour Ahmed
Keyword(s):  
Interaction Energy ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Water Interface ◽  
Mineral Surfaces ◽  
Soil Mineral ◽  
Phosphorus Adsorption ◽  
Covalent Bonds ◽  
Binding Mechanisms

The phosphorus (P) immobilization and thus its availability for plants are mainly affected by the strong interaction of phosphates with soil components especially soil mineral surfaces. Related reactions have been studied extensively via sorption experiments especially by carrying out adsorption of ortho-phosphate onto Fe-oxide surfaces. But a molecular-level understanding for the P-binding mechanisms at the mineral-water interface is still lacking, especially for forest eco-systems. Therefore, the current contribution provides an investigation of the molecular binding mechanisms for two abundant phosphates in forest soils, inositol hexaphosphate (IHP) and glycerolphosphate (GP), at the diaspore mineral surface. Here a hybrid electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) based molecular dynamics simulation has been applied to explore the diaspore-IHP/GP-water interactions. The results provide evidence for the formation of different P-diaspore binding motifs involving monodentate (M) and bidentate (B) for GP and two (2M) as well as three (3M) monodentate for IHP. The interaction energy results indicated the abundance of the GP B motif compared to the M one. The IHP 3M motif has a higher total interaction energy compared to its 2M motif, but exhibits a lower interaction energy per bond. Compared to GP, IHP exhibited stronger interaction with the surface as well as with water. Water was found to play an important role in controlling these diaspore-IHP/GP-water interactions. The interfacial water molecules form moderately strong H-bonds (HBs) with GP and IHP as well as with the diaspore surface. For all the diaspore-IHP/GP-water complexes, the interaction of water with diaspore exceeds that with the studied phosphates. Furthermore, some water molecules form covalent bonds with diaspore Al atoms while others dissociate at the surface to protons and hydroxyl groups leading to proton transfer processes. Finally, the current results confirm previous experimental conclusions indicating the importance of the number of phosphate groups, HBs, and proton transfers in controlling the P-binding at soil mineral surfaces.

Synthesis and Biological Activity of Embelin and its Derivatives: An Overview

2020 ◽  
Vol 20 (5) ◽  
pp. 396-407 ◽  
Author(s):  
Zhaojun Sheng ◽  
Siyuan Ge ◽  
Min Gao ◽  
Rongchao Jian ◽  
Xiaole Chen ◽  
...  
Keyword(s):  
Biological Activity ◽  
Biological Effects ◽  
New Drugs ◽  
Hydroxyl Groups ◽  
Carbonyl Groups ◽  
Cellular Mechanisms ◽  
Embelia Ribes ◽  
Naturally Occurring ◽  
Ic50 Value ◽  
Apoptosis Protein

Embelin is a naturally occurring para-benzoquinone isolated from Embelia ribes (Burm. f.) of the Myrsinaceae family, and contains two carbonyl groups, a methine group and two hydroxyl groups. With embelin as the lead compound, more than one hundred derivatives have been reported. Embelin is well known for its ability to antagonize the X-linked inhibitor of apoptosis protein (XIAP) with an IC50 value of 4.1 μM. The potential of embelin and its derivatives in the treatment of various cancers has been extensively studied. In addition, these compounds display a variety of other biological effects: antimicrobial, antioxidant, analgesic, anti-inflammatory, anxiolytic and antifertility activity. This paper reviews the recent progress in the synthesis and biological activity of embelin and its derivatives. Their cellular mechanisms of action and prospects in the research and development of new drugs are also discussed.

scholarly journals Tentative Peptide‒Lipid Bilayer Models Elucidating Molecular Behaviors and Interactions Driving Passive Cellular Uptake of Collagen-Derived Small Peptides

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 710
Author(s):  
Pathomwat Wongrattanakamon ◽  
Wipawadee Yooin ◽  
Busaban Sirithunyalug ◽  
Piyarat Nimmanpipug ◽  
Supat Jiranusornkul
Keyword(s):  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Mean Square Displacement ◽  
Dynamics Simulation ◽  
Coordinate Frame ◽  
Mean Square ◽  
Binding Modes ◽  
Small Peptides ◽  
Collagen Peptides ◽  
Electron Density Profiles

Collagen contains hydroxyproline (Hyp), which is a unique amino acid. Three collagen-derived small peptides (Gly-Pro-Hyp, Pro-Hyp, and Gly-Hyp) interacting across a lipid bilayer (POPC model membrane) for cellular uptakes of these collagen-derived small peptides were studied using accelerated molecular dynamics simulation. The ligands were investigated for their binding modes, hydrogen bonds in each coordinate frame, and mean square displacement (MSD) in the Z direction. The lipid bilayers were evaluated for mass and electron density profiles of the lipid molecules, surface area of the head groups, and root mean square deviation (RMSD). The simulation results show that hydrogen bonding between the small collagen peptides and plasma membrane plays a significant role in their internalization. The translocation of the small collagen peptides across the cell membranes was shown. Pro-Hyp laterally condensed the membrane, resulting in an increase in the bilayer thickness and rigidity. Perception regarding molecular behaviors of collagen-derived peptides within the cell membrane, including their interactions, provides the novel design of specific bioactive collagen peptides for their applications.

scholarly journals The Adhesion and Diffusion of Saturate, Asphaltene, Resin and Aromatic (SARA) Molecules on Oxygenated and Hydrogenated Carbon Nanotubes (CNTs)

2021 ◽  
Vol 6 (9) ◽  
pp. 123
Author(s):  
Mehdi Shishehbor ◽  
Hadi S. Esmaeeli ◽  
M. Reza Pouranian
Keyword(s):  
Carbon Nanotubes ◽  
Interfacial Adhesion ◽  
Asphalt Binder ◽  
Adhesion Energy ◽  
Dynamics Simulation ◽  
Hydroxyl Groups ◽  
Reactive Molecular Dynamics ◽  
Cnts Surface ◽  
And Diffusion ◽  
Diffusion Properties

The interfacial adhesion between asphalt binder and carbon nanotubes (CNTs) depends on many nanoscopic properties such as diffusion of SARA molecules on CNTs surface. Functionalization of CNTs with Oxygens (O=CNTs), hydroxyl groups (HO–CNTs), and hydrogens (H–CNTs) has been an effective way to modify the surface properties of CNTs and ultimately the macroscopic properties of the CNT-composites. This paper presents the effect of different dosages of oxygenated and hydrogenated CNTs on the adhesion and diffusion of SARA molecules on CNTs’ surfaces. First, reactive molecular dynamics simulation is used to oxygenate and hydrogenate CNTs up to a certain dosage. Next, it is employed to model the interaction and diffusion of SARA molecules with the functionalized CNTs. We employ the steer molecular dynamic (SMD) and Einstein formula to calculate the adhesion and diffusion properties. The results demonstrate that hydrogenation has little effect on the adhesion energy, while oxygenation can increase adhesion energy up to 100% for 25% dosage. The diffusion coefficient dramatically drops for both oxygenated and hydrogenated CNTs, with lower values for the latter. We observe that for hydrogenated and oxygenated CNTs at different dosages, asphaltene, resin, aromatic, and saturate molecules have the highest to lowest values, respectively.

scholarly journals Phase behavior and thermal dynamic properties of free volume on SMMA/SMA copolymer blend studied by PALS method

2006 ◽  
Vol 55 (6) ◽  
pp. 3136
Author(s):  
Jiang Zhong-Ying ◽  
Yu Wei-Zhong ◽  
Huang Yan-Jun ◽  
Xia Yuan-Fu ◽  
Ma Shu-Xin
Keyword(s):  
Phase Behavior ◽  
Free Volume ◽  
Dynamic Properties ◽  
Copolymer Blend

Dynamics and Traffic for Transfecting Exogenous MicroRNA as Studied by Live-Cell Microscopy

2021 ◽  
Vol 17 (8) ◽  
pp. 1647-1653
Author(s):  
Ke Yang ◽  
Yuanyuan Wang ◽  
Bo Sun ◽  
Tian Tian ◽  
Zhu Dai ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Mean Square Displacement ◽  
Small Region ◽  
Single Particle Tracking ◽  
Live Cell ◽  
Calculation Results ◽  
Long Time ◽  
Live Cell Microscopy ◽  
Cell Microscopy

MicroRNA (miRNA) has emerged as an important gene-regulator that shows great potential in gene therapy because of its unique roles in gene-regulation. However, the knowledge on their function and transportation in vivo is still lacking, and there are limited obvious evidences to define intracellular transportation of miRNA. In this study, the dynamics of exogenous miR-21 transfected into HeLa cells was traced by live-cell microscopy. Their transportation at key time points was recorded and dynamic properties were analyzed by single particle tracking (SPT) and mean square displacement (MSD) calculation. Results showed that the exogenous miRNAs bounded to cells quickly and went through lysosome into cytosol, where they were subsequently recruited into p-body. They finally were degraded, otherwise went back to cytosol in some way. Long time observation and analysis of motion mode showed that the miRNAs were confined in a small region and their motion modes were flexible in different intracellular microenvironment after entering the cells.

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