Glass Transition in Sub-nanometer Confinement

1998 ◽  
Vol 543 ◽  
Author(s):  
A. Huwe ◽  
F. Kremer ◽  
M. Arndt ◽  
P. Behrens ◽  
W. Schwieger ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Relaxation Rate ◽  
Pore Size ◽  
Coordination Number ◽  
Single Molecule ◽  
Bulk Liquid ◽  
Bond Forming ◽  
Broadband Dielectric Spectroscopy ◽  
Molecule Dynamics

AbstractBroadband dielectric spectroscopy (10−2 Hz - 109Hz) is employed to study the molecular dynamics of low-molecular-weight glassforming liquids being confined to nanopores. For the H-bond forming liquid propylene glycol being confined to (uncoated and silanized) nanopores (pore size: 2.5 nm, 5.0 nm and 7.5 nm) a molecular dynamics is observed which is comparable to that of the bulk liquid. Due to surface effects in uncoated nanopores the relaxation time distribution is broadened on the long term side and the mean relaxation rate is decreased by about half a decade. This effect can be counterbalanced by lubricating the inner surfaces of the pores resulting in a relaxation rate which is slightly faster compared to the bulk liquid. For the H-bonded liquid ethylene glycol (EG) embedded in zeolites of different pore size and topology one observes a sharp transition from a single-molecule dynamics to that of a liquid depending on the coordination number of the confined molecules. While EG in silicalite (showing a single molecule relaxation) has four neighboring molecules, EG in zeolite beta or AIPO4-5 has a coordination number of five and behaves like a bulk liquid.

Multidimensional Characterization of Single‐Molecule Dynamics in a Plasmonic Nanocavity

2021 ◽  
Author(s):  
Lucas Domulevicz ◽  
Hyunhak Jeong ◽  
Nayan K. Paul ◽  
Juan Sebastian Gomez-Diaz ◽  
Joshua Hihath
Keyword(s):  
Single Molecule ◽  
Single Molecule Dynamics ◽  
Molecule Dynamics

Advances in the study of the mechanochemical coupling of kinesin

2018 ◽  
Vol 32 (18) ◽  
pp. 1840001 ◽  
Author(s):  
Ming Li ◽  
Zhong-Can Ou-Yang ◽  
Yao-Gen Shu
Keyword(s):  
Molecular Dynamics ◽  
Single Molecule ◽  
Intracellular Transport ◽  
Coordination Mechanism ◽  
Personal Perspective ◽  
Long Distance ◽  
Future Studies ◽  
Mechanochemical Coupling ◽  
Dynamics Simulations ◽  
Made In

Kinesin is a two-headed linear motor for intracellular transport. It can walk a long distance in a hand-over-hand manner along the track before detaching (i.e., high processivity), and it consumes one ATP molecule for each step (i.e., tight mechanochemical coupling). The mechanisms of the coordination of its two heads and the mechanochemical coupling are the central issues of numerous researches. A few advances have been made in recent decades, thanks to the development of single-molecule technologies and molecular dynamics simulations. In this paper, we review some progress of the studies on the kinematics, energetics, coordination mechanism, mechanochemical mechanism of kinesin. We also present a personal perspective on the future studies of kinesin.

Molecular Dynamics Study of Microscopic Mechanism of Diffusion in Li2SiO3 System

1991 ◽  
Vol 46 (7) ◽  
pp. 616-620 ◽  
Author(s):  
Junko Habasaki
Keyword(s):  
Molecular Dynamics ◽  
Coordination Number ◽  
Md Simulation ◽  
Mean Square Displacement ◽  
Mean Square ◽  
Lithium Ions ◽  
Microscopic Mechanism ◽  
Trapping Model ◽  
The Mean

MD simulation has been performed to learn the microscopic mechanism of diffusion of ions in the Li2SiO3 system. The motion of lithium ions can be explained by the trapping model, where lithium is trapped in the polyhedron and moves with fluctuation of the coordination number. The mean square displacement of lithium was found to correlate well with the net changes in coordination number.

Single-molecule dynamics of site-specific labeled transforming growth factor type II receptors on living cells

2014 ◽  
Vol 50 (94) ◽  
pp. 14724-14727 ◽  
Author(s):  
Ming Cheng ◽  
Wei Zhang ◽  
Jinghe Yuan ◽  
Wangxi Luo ◽  
Nan Li ◽  
...  
Keyword(s):  
Growth Factor ◽  
Single Molecule ◽  
Transforming Growth Factor ◽  
Living Cells ◽  
Unnatural Amino Acid ◽  
Type Ii ◽  
Site Specific ◽  
Single Molecule Dynamics ◽  
Factor Type ◽  
Molecule Dynamics

Single-molecule dynamics of the transforming growth factor type II receptor (TβRII) labeled by an unnatural amino acid.

Theoretical Study of Iron Heterogeneous Growth on the Surface of C60 Molecule

2014 ◽  
Vol 1081 ◽  
pp. 115-118
Author(s):  
Qi Cheng Liu ◽  
Yun Fang Li
Keyword(s):  
Crystallization Process ◽  
Theoretical Study ◽  
Covalent Bond ◽  
Md Simulations ◽  
Nucleation And Growth ◽  
Bond Forming ◽  
Regular Icosahedron ◽  
Molecule Dynamics ◽  
Molecule Surface ◽  
Regular Closed

Direct molecule dynamics (MD) simulations have also been performed to study heterogeneous nucleation and growth of iron on C60 molecule. The grown mechanism of this crystallization process was explored. The results indicate that 92 iron atoms attach to C60 molecule surface can form new covalent bond, forming a closed regular icosahedron. More atoms grow in layer to form bigger regular closed clathrate base on the structure of former one. As increase of atoms number, there will appear some crystal faces.

Foam Flow in Different Pore Systems—Part 1: The Roles of Pore Attributes and Their Variation on Trapping and Apparent Viscosity of Foam

SPE Journal ◽  
2021 ◽  
pp. 1-18 ◽  
Author(s):  
Abdulrauf Rasheed Adebayo
Keyword(s):  
Porous Medium ◽  
Aspect Ratio ◽  
Pore Size ◽  
Coordination Number ◽  
Apparent Viscosity ◽  
Absolute Permeability ◽  
Surface Relaxation ◽  
Foam Flow ◽  
Rock Samples ◽  
Lower Permeability

Summary Lateral propagation of foam in heterogeneous reservoirs, where pore geometries vary laterally, depends on the roles of pore geometries on the foam properties. In this paper, the pore attributes of 12 different rock samples were characterized in terms of porosity, permeability, pore shape, pore size, throat size, aspect ratio, coordination number, and log mean of surface relaxation times (T2LM). These were measured from gas porosimeter and permeameter, X-ray microcomputed tomography (CT)-basedpore-network models, thin-section photomicrographs, and nuclear magnetic resonance (NMR) surface relaxometry. The samples have a wide range of porosity: 12 to 29%; permeability: 1 to 5,000 md; average pore size: 3.7 to 9 µm; average throat size: 2.4 to 8 µm; average aspect ratio: 1 to 1.7; average coordination number: 2.6 to 5.2; and T2LM: 9.4 to 740 ms. Nitrogen foam flow experiments (without oil) were then conducted on each rock sample using a specialized coreflood apparatus. A graphical analysis of the coreflood data was used to estimate the total saturation of trapped foam (10 to 66%), flowing foam (3 to 14%), and apparent viscosity of foam (3.2 to 73 cp). Trapped foam saturation and apparent viscosity values were then correlated with each of the measured pore attributes. The results revealed that all pore attributes, except aspect ratio, have positive correlations with foam trapping and apparent viscosity. The best correlation with trapped foam saturation was obtained when the most influential pore attributes (pore size, throat size, aspect ratio, and coordination number) were combined into a single mathematical function. Foam apparent viscosity also appears to be mostly influenced by trapped foam saturation, permeability, and coordination number of pore systems. Trapping is also likely enhanced by the presence of fenestral or channel pores. Furthermore, the shape and angularity of pores seem to facilitate snap-off and trapping of foam, because rock samples with angular pores trapped the highest foam saturation compared with other samples with rounded and subrounded pores. It was also shown that the correlation between trapped foam saturation (and foam apparent viscosity) and the absolute permeability of porous media may reverse at some high-permeability values (greater than several darcies), when one or both of the following conditions exist: (1) The aspect ratio of a lower-permeability porous medium is lower than that of a higher-permeability porous medium, and (2) the coordination number of a lower-permeability porous medium is higher than that of a higher-permeability porous medium. Finally, T2LM showed a good correlation with foam trapping, making NMR logging a prospective tool for pre-evaluating foam performance in targeted reservoir sections.

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