scholarly journals Superlubricity under ultrahigh contact pressure enabled by partially oxidized black phosphorus nanosheets

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Xiaoyong Ren ◽  
Xiao Yang ◽  
Guoxin Xie ◽  
Feng He ◽  
Rong Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Contact Pressure ◽  
Industrial Applications ◽  
Black Phosphorus ◽  
Operating Conditions ◽  
Environmental Benefits ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
High Contact Pressure ◽  
Liquid Superlubricity

AbstractSuperlubricity has recently raised an increasing interest owing to its great potential in energy saving and environmental benefits. Yet how to obtain stable superlubricity under an ultrahigh contact pressure (>1 GPa) still remains a challenge. Here, we demonstrate that robust liquid superlubricity can be realized even under a contact pressure of 1193 MPa by lubrication with partially oxidized black phosphorus (oBP) nanosheets. The analysis indicates that the oBP nanosheets that absorb large amounts of water molecules are retained at the friction interface and transform the friction pairs interface to that between the oBP nanosheets. Molecular dynamics simulation demonstrates that water molecules could be retained at the friction interface even under the ultrahigh contact pressure owing to the abundant P=O and P–OH bonds formed on the oBP nanosheet surfaces, contributing to the achievement of stable superlubricity under the ultrahigh contact pressure. This work has the potential of introducing the liquid superlubricity concept in diverse industrial applications involving high-contact-pressure operating conditions.

scholarly journals The Impact of the Electric Field on Surface Condensation of Water Vapor: Insight from Molecular Dynamics Simulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 64 ◽  
Author(s):  
Qin Wang ◽  
Hui Xie ◽  
Zhiming Hu ◽  
Chao Liu
Keyword(s):  
Molecular Dynamics ◽  
Water Vapor ◽  
Electric Field ◽  
Intermolecular Forces ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Attraction Force ◽  
Condensation Rate ◽  
Shape Transformation ◽  
The Impact

In this study, molecular dynamics simulations were carried out to study the coupling effect of electric field strength and surface wettability on the condensation process of water vapor. Our results show that an electric field can rotate water molecules upward and restrict condensation. Formed clusters are stretched to become columns above the threshold strength of the field, causing the condensation rate to drop quickly. The enhancement of surface attraction force boosts the rearrangement of water molecules adjacent to the surface and exaggerates the threshold value for shape transformation. In addition, the contact area between clusters and the surface increases with increasing amounts of surface attraction force, which raises the condensation efficiency. Thus, the condensation rate of water vapor on a surface under an electric field is determined by competition between intermolecular forces from the electric field and the surface.

scholarly journals Effects of the Temperature and the pH on the Main Protease of SARS-CoV-2: A Molecular Dynamics Simulation Study

2021 ◽  
Vol 12 (6) ◽  
pp. 7239-7248
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Root Mean Square ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Water Molecules ◽  
Mean Square ◽  
Main Protease ◽  
Decreasing Ph ◽  
Increasing Temperature

The novel coronavirus, recognized as COVID-19, is the cause of an infection outbreak in December 2019. The effect of temperature and pH changes on the main protease of SARS-CoV-2 were investigated using all-atom molecular dynamics simulation. The obtained results from the root mean square deviation (RMSD) and root mean square fluctuations (RMSF) analyses showed that at a constant temperature of 25℃ and pH=5, the conformational change of the main protease is more significant than that of pH=6 and 7. Also, by increasing temperature from 25℃ to 55℃ at constant pH=7, a remarkable change in protein structure was observed. The radial probability of water molecules around the main protease was decreased by increasing temperature and decreasing pH. The weakening of the binding energy between the main protease and water molecules due to the increasing temperature and decreasing pH has reduced the number of hydrogen bonds between the main protease and water molecules. Finding conditions that alter the conformation of the main protease could be fundamental because this change could affect the virus’s functionality and its ability to impose illness.

Effects of Free Surface Evaporation on Water Nano-Droplet Wetting Kinetics: A Molecular Dynamics Study

2013 ◽  
Author(s):  
Gui Lu ◽  
Yuan-Yuan Duan ◽  
Xiao-Dong Wang
Keyword(s):  
Molecular Dynamics ◽  
Free Surface ◽  
Contact Line ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Dynamic Wetting ◽  
Surface Evaporation ◽  
Molecular Kinetic Theory ◽  
Line Region ◽  
Wetting Kinetics

The dynamic wetting of water nano-droplet with evaporation on the heated gold substrate was examined using molecular dynamics simulation. Various substrate and droplet pre-heated temperatures were calculated to obtained different evaporating rates. Water molecules attachment-detachment details were traced near the contact line region to show the microscopic details and evidences for the spreading-evaporating droplet. The increasing substrate temperature greatly affected the dynamic wetting process, while the initial temperature of water droplet had very limited effects. The effects of free surface evaporation on wetting kinetics for both hydrophobic and hydrophilic substrates were examined. The radius versus time curves agree well with the Molecular kinetic theory (MKT) for spreading without evaporation and deviate from the MKT for the spreading with evaporation. The enhancement on wetting kinetics due to evaporation can be attributed to the reducing of liquid-vapor surface tension and the strengthening in water molecules transport in contact line region and bulk droplet.

scholarly journals Molecular Dynamics Simulation of Distribution and Diffusion Behaviour of Oil–Water Interfaces

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1905 ◽  
Author(s):  
Chengbin Zhang ◽  
Hanhui Dai ◽  
Pengfei Lu ◽  
Liangyu Wu ◽  
Bo Zhou ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Interface Roughness ◽  
Dynamics Simulation ◽  
Water Phase ◽  
Water Molecules ◽  
Water Interface ◽  
Oil Water ◽  
And Diffusion ◽  
Diffusion Behaviors

The distribution and diffusion behaviors of microscopic particles at fluorobenzene–water and pentanol–water interfaces are investigated using molecular dynamics simulation. The influences of Na+/Cl− ions and the steric effects of organic molecules are examined. The concentration distributions of different species, the orientations of oil molecules at the interface, and oil–water interface morphology as well as the diffusion behaviors of water molecules are explored and analyzed. The results indicate that a few fluorobenzene molecules move into the water phase influenced by Na+/Cl− ions, while the pentanol molecules at the interface prefer orientating their hydrophilic groups toward the water phase due to their large size. The water molecules more easily burst into the pentanol phase with larger molecular spaces. As the concentration of ions in the water phase increases, more water molecules enter into the pentanol molecules, leading to larger interface roughness and interface thickness. In addition, a lower diffusion coefficient for water molecules at the fluorobenzene–water interface are observed when introducing Na+/Cl− ions in the water phase, while for the pentanol–water system, the mobility of interfacial water molecules are enhanced with less ions and inhibited with more ions.

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