molecular chain
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2022 ◽  
Vol 572 ◽  
pp. 151238
Author(s):  
Dejian Zou ◽  
Tongmin Yu ◽  
Chunzheng Duan

2022 ◽  
Vol 2155 (1) ◽  
pp. 012031
Author(s):  
A.N. Korshunova ◽  
V.D. Lakhno

Abstract In this work, we consider the motion of a polaron in a polynucleotide Holstein molecular chain in a constant electric field. It is shown that the character of the polaron motion in the chain depends not only on the chosen parameters of the chain, but also on the initial distribution of the charge along the chain. It is shown that for a small set value of the electric field intensity and for fixed values of the chain parameters, changing only the initial distribution of the charge in the chain, it is possible to observe either a uniform movement of the charge along the chain, or an oscillatory mode of charge movement.


Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1401
Author(s):  
Xuanlai Chen ◽  
Guochao Yan ◽  
Xianglin Yang ◽  
Guang Xu

In order to explore the adsorption characteristics of sulfonate gemini surfactants on the surface of lignite, the molecular dynamics simulation method was used, and A kind of sulfonic acid bis sodium salt (S2) and the sodium dodecyl sulfate (SDS) were selected. A binary model of surfactant/lignite adsorption system and a ternary model of water/surfactant/lignite system were constructed, and a series of properties such as adsorption configuration, interaction energy, order parameters, relative concentration distribution, number of hydrogen bonds, etc., were analyzed. The results showed that the adsorption strength of S2 on the surface of lignite was higher than that of SDS. The results indicated that the large-angle molecular chain in S2 tended to become smaller, the small-angle molecular chain tended to become larger, and the angle between the molecular chains and the Z axis tended to be concentrated, making the formed network structure denser during the adsorption process. The number of hydrogen bonds in the water-coal system was 42, and the number of hydrogen bonds in the system after S2 adsorption was 15, which was much lower than the 23 hydrogen bonds in the system after SDS adsorption, and S2 could better adsorb and wrap the oxygen-containing groups on the surface of the lignite. The comparative study of the adsorption characteristics of the two surfactants on the surface of lignite can help us better understand the influence of the surfactant structure on the adsorption strength. The research results have important theoretical and practical significance for developing new surfactants, and enriching and developing the basic theory of coal wettability.


2021 ◽  
Author(s):  
Chun’an Du ◽  
Xianya Zhang ◽  
Weiwei Chen ◽  
Peng Xu

The researches on the influence of sodium ion on mechanism of polymer solution viscosity loss were conducted. Scanning electron microscopy was used to analyze the polymer microstructure. Molecular dynamics simulation was employed to reveal the influence of sodium ion on the polymer molecular configuration. The results shown: the polymer viscosity loss was more than 70% when the concentration of sodium ion was above 4000 mg/L. The results of microstructure and molecular conformation analysis indicated that the main reason of viscosity loss was the electrostatic attraction between sodium ion and negatively charged groups of polymer molecule chains, which cause compression of polymer molecular chain. The coil and shrinkage of polymer molecular chain led to the breakage of the spatial network structure of macromolecules.


Polymer ◽  
2021 ◽  
Vol 233 ◽  
pp. 124230
Author(s):  
Wenjie Yu ◽  
Ning Xiang ◽  
Maoyuan Li ◽  
Guancheng Shen ◽  
Xiaowei Zhou ◽  
...  

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2746
Author(s):  
Minhee Kim ◽  
Se-Hee Lee

In an HVDC environment, space charge accumulated in polymeric insulators causes severe electric field distortion and degradation of breakdown strength. To analyze the breakdown characteristics, here, the space charge distribution was numerically evaluated using the bipolar charge transport (BCT) model, considering the temperature gradient inside the polymeric insulator. In particular, we proposed an electro-mechanical threshold energy condition, resulting in the modified molecular chain displacement model. The temperature gradient accelerates to reduce the breakdown strength with the polarity-reversal voltage, except during the harshest condition, when the temperature of the entire polymeric insulator was 70 °C. The energy imbalance inside the insulator caused by polarity-reversal voltage reduced the breakdown strength by 82%. Finally, this numerical analysis model can be used universally to predict the breakdown strength of polymeric insulators in various environments, and help in evaluating the electrical performance of polymeric insulators.


2021 ◽  
pp. 131209
Author(s):  
Zechun Li ◽  
Changjin Yang ◽  
Yanchan Wei ◽  
Yuanbing Zhou ◽  
Shuangquan Liao

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