Diffusion Constants near the Critical Point for Time-Dependent Ising Models. III. Self-Diffusion Constant

1966 ◽  
Vol 150 (1) ◽  
pp. 285-290 ◽  
Author(s):  
Kyozi Kawasaki
Keyword(s):  
Critical Point ◽  
Diffusion Constant ◽  
Ising Models ◽  
Time Dependent ◽  
Self Diffusion ◽  
Diffusion Constants

scholarly journals Water and Deuterium Oxide Permeability through Aquaporin 1: MD Predictions and Experimental Verification

2007 ◽  
Vol 130 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Artem B. Mamonov ◽  
Rob D. Coalson ◽  
Mark L. Zeidel ◽  
John C. Mathai
Keyword(s):  
Deuterium Oxide ◽  
Diffusion Constant ◽  
Structural Data ◽  
Md Simulations ◽  
Water Model ◽  
Aquaporin 1 ◽  
Self Diffusion ◽  
Osmotic Permeability ◽  
Protein Channels ◽  
And Diffusion

Determining the mechanisms of flux through protein channels requires a combination of structural data, permeability measurement, and molecular dynamics (MD) simulations. To further clarify the mechanism of flux through aquaporin 1 (AQP1), osmotic pf (cm3/s/pore) and diffusion pd (cm3/s/pore) permeability coefficients per pore of H2O and D2O in AQP1 were calculated using MD simulations. We then compared the simulation results with experimental measurements of the osmotic AQP1 permeabilities of H2O and D2O. In this manner we evaluated the ability of MD simulations to predict actual flux results. For the MD simulations, the force field parameters of the D2O model were reparameterized from the TIP3P water model to reproduce the experimentally observed difference in the bulk self diffusion constants of H2O vs. D2O. Two MD systems (one for each solvent) were constructed, each containing explicit palmitoyl-oleoyl-phosphatidyl-ethanolamine (POPE) phospholipid molecules, solvent, and AQP1. It was found that the calculated value of pf for D2O is ∼15% smaller than for H2O. Bovine AQP1 was reconstituted into palmitoyl-oleoyl-phosphatidylcholine (POPC) liposomes, and it was found that the measured macroscopic osmotic permeability coefficient Pf (cm/s) of D2O is ∼21% lower than for H2O. The combined computational and experimental results suggest that deuterium oxide permeability through AQP1 is similar to that of water. The slightly lower observed osmotic permeability of D2O compared to H2O in AQP1 is most likely due to the lower self diffusion constant of D2O.

scholarly journals A rapid method for determining diffusion constants in solution

1948 ◽  
Vol 192 (1030) ◽  
pp. 382-402 ◽  
Keyword(s):  
Monochromatic Light ◽  
Diffusion Constant ◽  
Initial Boundary ◽  
Optic Axis ◽  
Theory And Practice ◽  
Dilute Solution ◽  
Sharp Boundary ◽  
Diffusion Constants ◽  
A Cell ◽  
Molecular Substances

A method has been rediscovered, and developed in theory and practice, for optical observation of the earliest stages of diffusion across an initially sharp boundary between a dilute solution and a solvent. It enables the diffusion constant of a monodisperse solute to be measured about fifty times as quickly as by other methods, at lower concentration and possibly with greater accuracy; it should therefore be particularly valuable for the study of high molecular substances. The method is based on the interference pattern which is formed when monochromatic light from a horizontal slit is focused after passing through a cell where diffusion is occurring. The pattern, a set of horizontal bands, contracts towards the optic axis as diffusion proceeds, at a rate from which the diffusion constant can be calculated. By counting the bands in the pattern the refractive increment of the solute can be determined. The sharp initial boundary is obtained by flowing the solution and solvent out through a common narrow horizontal slit. The construction, calibration, and use of the apparatus are described.

DIFFUSION OF Tl+ IONS THROUGH THE INTERFACE OF SOLID NaCl, KCl OR RbCl AND LIQUID TlCl

2002 ◽  
Vol 16 (01n02) ◽  
pp. 108-113
Author(s):  
W. YU ◽  
A. FUJII
Keyword(s):  
Sodium Chloride ◽  
Single Crystals ◽  
Optical Method ◽  
Diffusion Constant ◽  
Liquid Interface ◽  
Diffusion Constants ◽  
Diffusion Phenomena ◽  
Diffusion Source ◽  
Solid Liquid Interface ◽  
Solid Liquid

The diffusion phenomena of thallous ions ( Tl + ions) through solid-liquid interface of liquid Tl + ions diffusion source and sodium chloride (NaCl) , potassium chloride (KCl) or rubidium chloride (RbCl) single crystals are studied by optical method. The characterisic absorption peaks of Tl + center in NaCl, KCl or RbCl single crystals were used as the tracer for measurements and the diffusion constants are evaluated at various temperatures. The results show that the diffusion constant of solid-liquid interface is about 103 times larger than that of solid-solid interface of KCl and TlCl .

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