Chloride Ion Hydration and Diffusion in Supercritical Water Using a Polarizable Water Model

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.

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Effect of Stone Powder Content on the Diffusing Parameter and Diffusion Attenuation Coefficient of Chloride Ion of Mechanical Sand Concrete

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.584-586.1818 ◽

2014 ◽

Vol 584-586 ◽

pp. 1818-1822

Author(s):

Ming Qiang Qin ◽

Wen Zhan ◽

Wen Bing Xu ◽

Jin Hui Li

Keyword(s):

Attenuation Coefficient ◽

Chloride Ion ◽

Chloride Diffusion ◽

Chloride Diffusion Coefficient ◽

River Sand ◽

Moderate Amount ◽

Powder Content ◽

And Diffusion ◽

Better Than

The effect of stone powder content on the chloride diffusion coefficient and diffusion attenuation coefficient of chloride ion of mechanical sand (MS) concrete was studied. The results showed that the resistance to chloride ion permeability of MS concrete firstly increased and then decreased with the increase of the content of stone powder. The anti-permeability of the concrete which had moderate amount of stone powder was better than that of the natural river sand (NS) concrete. The diffusion attenuation coefficient of MS concrete was greater than that of the NS concrete, which was good for long-term durability of concrete structure.

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Ion Hydration in Supercritical Water

Industrial & Engineering Chemistry Research ◽

10.1021/ie00035a035 ◽

1994 ◽

Vol 33 (11) ◽

pp. 2819-2829 ◽

Cited By ~ 3

Author(s):

Ram B. Gupta ◽

Keith P. Johnston

Keyword(s):

Supercritical Water ◽

Ion Hydration

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Transport of Water and Chloride Ion in Cement Composites Modified with Graphene Nanoplatelet

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.629-630.162 ◽

2014 ◽

Vol 629-630 ◽

pp. 162-167 ◽

Cited By ~ 2

Author(s):

Hong Jian Du ◽

Sze Dai Pang

Keyword(s):

Chloride Ion ◽

Chloride Ions ◽

Chloride Diffusion ◽

Cement Composites ◽

Chloride Diffusion Coefficient ◽

Barrier Effect ◽

Graphene Nanoplatelet ◽

Chloride Migration ◽

Corrosion Of Steel ◽

And Diffusion

Cement composites are vulnerable to harsh environments in which the chloride ions can ingress into concrete and thus cause corrosion of steel. In this study, the barrier effect of adding 2-D nanoparticles on the transport properties of cement-based materials was investigated. Graphene nanoplatelet (GNP), which comprises of a few layers of graphene stacked together, is chosen as a candidate in this study due to its impermeability and also its electrical conductivity which can be exploited for self-sensing functionality. Due to the large aspect ratio of the GNP, it is expected that the dispersion of these 2-D nanobarriers can contribute to the reduced permeability and diffusion of harmful agents. Experiments were carried out on cement mortar with 0%, 2.5%, 5.0% and 7.5% of GNP by weight of cement. The water penetration depth, chloride diffusion coefficient and chloride migration coefficient were reduced by 64%, 70% and 31% respectively with the addition of as little as 2.5% of GNP. This reduction can be attributed to the barrier effect of GNP which increases the tortuosity against water and chloride ions penetration, and also the refinement of the capillary pores which was revealed from the MIP tests. At GNP content exceeding 5%, the nanoparticles agglomerate, causing weak pockets which compromises the benefits of adding GNP to impede the ingress of fluids.

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EXAMINATION ON PENETRATION AND DIFFUSION OF CHLORIDE ION INTO CONCRETE IN ACCELERATED TEST AND EXPOSURE TEST

Journal of Structural and Construction Engineering (Transactions of AIJ) ◽

10.3130/aijs.81.643 ◽

2016 ◽

Vol 81 (722) ◽

pp. 643-653

Author(s):

Tatsuki KANEKO ◽

Michihiko ABE ◽

Yoshihiro MASUDA

Keyword(s):

Chloride Ion ◽

Accelerated Test ◽

Exposure Test ◽

And Diffusion

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Relationship between Pore Structure and Chloride Ion Diffusivity in Cementitious Materials

10.20944/preprints201812.0248.v1 ◽

2018 ◽

Author(s):

Yuya Sakai

Keyword(s):

Pore Structure ◽

Cement Paste ◽

Pore Diameter ◽

Chloride Ion ◽

Total Porosity ◽

Cementitious Materials ◽

The Other ◽

Diffusion Test ◽

Other Hand ◽

And Diffusion

In this study, literature on pore structure and chloride ion diffusivity was collected to investigate the correlation of pore structure indicators with diffusivity. Good correlation between total porosity and chloride ion diffusivity was found when the samples did not contain admixture materials and diffusion test was conducted without acceleration. Pore diameter indicators did not correlate with diffusivity. The diffusivity of cement paste was reduced by admixture materials compared to that without admixture materials even if the total porosity is the same. On the other hand, the diffusivity of concrete was not reduced by admixture materials.

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