Self-Diffusion Coefficients of Water

Wang, Jui H.

doi:10.1021/j100782a510

Cited by 170 publications

(93 citation statements)

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“…50 The bulk self-diffusion coefficient of water is 2.42 × 10 −9 m 2 /s, which is close to the reported experimental value of (2.27−2.57) × 10 −9 m 2 /s. 51,52 Meanwhile, the bulk self-diffusion coefficient of toluene is 2.49 × 10 −9 m 2 /s, which is good agreement with the value of 2.29 × 10 −9 m 2 /s in the previous simulation. 35 The diffusion coefficients of the coal and petroleum asphaltenes in toluene are found to be 5.14 × 10 −11 and 3.87 × 10 −11 m 2 /s, respectively, which agree with the reported experimental results of (2−7.5) × 10 −11 m 2 / s. 53 On the basis of these results, it is believed that the molecular modes and force field used in the simulations could well reflect the physical properties of various molecules (refer to the Supporting Information, Figures S1 and S2).…”

Section: Molecular Dynamics Simulationsupporting

confidence: 88%

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

2015

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It is well known that asphaltene molecules play a significant role in stabilizing emulsions of water in crude oil or diluted bitumen solutions. Molecular dynamics simulations were employed to investigate the aggregation and orientation behaviors of asphaltene molecules in a vacuum and at various water surfaces. Two different continental model asphaltene molecules were employed in this work. It was found that the initially disordered asphaltenes quickly self-assembled into ordered nanoaggregates consisting of several molecules, in which the aromatic rings in asphaltenes were reoriented to form a face-to-face stacked structure. More importantly, statistical analysis indicates that most of the stacked polycyclic aromatic planes of asphaltene nanoaggregates tend to be perpendicular to the water surface. If the asphaltene molecules are considered as "stakes", then the asphaltene nanoaggregate can be regarded as a "fence". All the fence-like nanoaggregates were twined and knitted together, which pinned them perpendicularly on the water surface to form a steady protective film wrapping the water droplets. The mechanism of stabilization of the water/oil emulsions is thereby well understood. Demulsification processes using a chemical demulsifier were also studied. It was observed that the asphaltene protective film was destroyed by a demulsifier of ethyl cellulose molecules, leading to exposure of the water droplet. The results obtained in this work will be of significance in guiding the development of demulsification technology.

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Section: Molecular Dynamics Simulationsupporting

confidence: 88%

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

2015

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“…7, which is consistent with complete disordering of bilayer 1 at 230 K. We emphasize that these comparisons are made in the inertial regime, which is ϳ0.4 ps from our results for simulated deuterated water and from the results of other studies. 27,53 Our calculated 56 self-diffusion coefficient for simulated deuterated water, 2.0ϫ10 Ϫ5 cm 2 s Ϫ1 , is in excellent agreement with the experimental value for liquid water, 1.97Ϯ0.02ϫ10 Ϫ5 cm 2 s Ϫ1 at 287 K, 18,72 but this may be a coincidence. Results obtained when bilayer 4 was not fixed are discussed in Sec.…”

Section: Translational Mobilitysupporting

confidence: 79%

First-principles molecular-dynamics study of surface disordering of the (0001) face of hexagonal ice

Mantz

Geiger

Molina

et al. 2000

The Journal of Chemical Physics

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In order to study surface disordering of ice at temperatures below the bulk melting point as a function of depth into the bulk, Car-Parrinello molecular-dynamics simulations of a periodic model of the hexagonal ice ͑0001͒ surface were carried out. Partial disorder in the uppermost bilayer was observed at a simulation temperature of 190 K, which is ϳ30 K below the estimated bulk melting point, qualitatively validating earlier classical molecular-dynamics studies of this phenomenon. Over 0.5 ps, the time scale of a simulation, there were three particularly useful ͑and complementary͒ measures of disorder: The pair distribution function g(r), the distance of the oxygen atoms from the bottommost bilayer, and the distribution of angles and formed by the molecular dipole vector and the Cartesian axes. Our results set the stage for future studies addressing the effect of the disordered ice surface on heterogeneous atmospheric chemistry.

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“…Temperature Dependence of P f and P d -The Arrhenius activation energy measured for normal control red cells (E a ϳ5 kcal/mol, Table II) was similar to the activation energy for diffusion of water in absence of any barrier (4.8 kcal/mol) (Wang, 1965). The activation energy for red cells totally deficient in AQP1 (10 -11 kcal/mol, Table II) was close to the value measured for water crossing simple lipid bilayers (12-14 kcal/ …”

Section: Aquaporin-1 Deficient Red Cellssupporting

confidence: 54%

Functional Analysis of Aquaporin-1 Deficient Red Cells

Mathai

Mori

Smith

et al. 1996

Journal of Biological Chemistry

125

109

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The aquaporin-1 (AQP1) water transport protein contains a polymorphism corresponding to the Colton red blood cell antigens. To define the fraction of membrane water permeability mediated by AQP1, red cells were obtained from human kindreds with the rare Coltonnull phenotype. Homozygosity or heterozygosity for deletion of exon I in AQP1 correlated with total or partial deficiency of AQP1 protein. Homozygote red cell morphology appeared normal, but clinical laboratory studies revealed slightly reduced red cell life span in vivo; deformability studies revealed a slight reduction in membrane surface area. Diffusional water permeability (P d ) was measured under isotonic conditions by pulsed field gradient NMR. Osmotic water permeability (P f ) was measured by change in light scattering after rapid exposure of red cells to increased extracellular osmolality. AQP1 contributes ϳ64% (P d ‫؍‬ 1.5 ؋ 10 ؊3 cm/s) of the total diffusional water permeability pathway, and lipid permeation apparently comprises ϳ23%. In contrast, AQP1 contributes >85% (P f ‫؍‬ 19 ؋ 10 ؊3 cm/s) of the total osmotic water permeability pathway, and lipid permeation apparently comprises only ϳ10%. The ratio of AQP1-mediated P f to P d predicts the length of the aqueous pore to be 36 Å.

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Self-Diffusion Coefficients of Water

Cited by 170 publications

References 0 publications

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

First-principles molecular-dynamics study of surface disordering of the (0001) face of hexagonal ice

Functional Analysis of Aquaporin-1 Deficient Red Cells

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