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| 2. |
- Boström, M., et al.
(författare)
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Dispersion Forces Stabilize Ice Coatings at Certain Gas Hydrate Interfaces That Prevent Water Wetting
- 2019
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Ingår i: ACS Earth and Space Chemistry. - : American Chemical Society. - 2472-3452. ; 3:6, s. 1014-1022
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Tidskriftsartikel (refereegranskat)abstract
- Gas hydrates formed in oceans and permafrost occur in vast quantities on Earth representing both a massive potential fuel source and a large threat in climate forecasts. They have been predicted to be important on other bodies in our solar systems such as Enceladus, a moon of Saturn. CO 2 -hydrates likely drive the massive gas-rich water plumes seen and sampled by the spacecraft Cassini, and the source of these hydrates is thought to be due to buoyant gas hydrate particles. Dispersion forces can in some cases cause gas hydrates at thermal equilibrium to be coated in a 3-4 nm thick film of ice, or to contact water directly, depending on which gas they contain. As an example, the results are valid at a quadruple point of the water-CO 2 gas hydrate system, where a film is formed not only for the model with pure ice but also in the presence of impurities in water or in the ice layer. These films are shown to significantly alter the properties of the gas hydrate clusters, for example, whether they float or sink. It is also expected to influence gas hydrate growth and gas leakage.
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| 3. |
- Boström, M., et al.
(författare)
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Non-perturbative theory of dispersion interactions
- 2015
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 90:3
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Tidskriftsartikel (refereegranskat)abstract
- Some open questions exist with fluctuation-induced forces between extended dipoles. Conventional intuition derives from large-separation perturbative approximations to dispersion force theory. Here, we present a full non-perturbative theory. In addition, we discuss how one can take into account finite dipole size corrections. It is of fundamental value to investigate the limits of validity of the perturbative dispersion force theory.
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| 4. |
- Thiyam, Priyadarshini, et al.
(författare)
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Effective lennard-jones parameters for CO2-CO2 dispersion interactions in water and near amorphous silica-water interfaces
- 2015
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Konferensbidrag (refereegranskat)abstract
- Different models for effective polarizability in water and the corresponding dispersion forces between dissolved molecules are explored in bulk water and near interfaces. We demonstrate that the attractive part of the Lennard-Jones parameters, i.e., the van der Waals parameter C6 (UvdW ≈ -C6/ρ6), is strongly modified when two carbon dioxide (CO2) molecules are near an amorphous silica-water and near a vapor-water interface. Standard simulation parameters for near-surface modeling are based on intermolecular forces in bulk media.
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| 5. |
- Thiyam, Priyadarshini, et al.
(författare)
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Effects of van der Waals forces and salt ions on the growth of water films on ice and the detachment of CO2 bubbles
- 2016
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 113:4
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Tidskriftsartikel (refereegranskat)abstract
- We study the effect of salts on the thickness of wetting films on melting ice and interactions acting on CO2 bubble near ice-water and vapor-water interfaces. Governing mechanisms are the Lifshitz and the double-layer interactions in the respective three-layer geometries. We demonstrate that the latter depend on the Casimir-Polder interaction of the salt ions dissolved in water with the respective ice, vapor and CO2 interfaces, as calculated using different models for their effective polarizability in water. Significant variation in the predicted thickness of the equilibrium water film is observed for different salt ions and when using different models for the ions' polarizabilities. We find that CO2 bubbles are attracted towards the ice-water interface and repelled from the vapor-water interface.
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| 6. |
- Thiyam, Priyadarshini, et al.
(författare)
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Ice Particles Sink below the Water Surface Due to a Balance of Salt, van der Waals, and Buoyancy Forces
- 2018
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:27, s. 15311-15317
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Tidskriftsartikel (refereegranskat)abstract
- According to the classical Archimedes' principle, ice floats in water and has a fraction of its volume above the water surface. However, for very small ice particles, other competing forces such as van der Waals forces due to fluctuating charge distributions and ionic forces due to salt ions and charge on the ice surface also contribute to the force balance. The latter crucially depends on both the pH of the water and the salt concentration. We show that a bulge in the air-water interface due to interaction of surface tension with the rising ice particle becomes significant when the particle radius is greater than 50-100 mu m. The role of these forces in governing the initial stages of ice condensation has never been considered. Here, we show that small ice particles can only form below an exclusion zone, from 2 nm (in high salt concentrations) up to 1 mu m (in pure water at pH 7) thick, under the water surface. This distance is defined by an equilibrium of upward buoyancy forces and repulsive van der Waals forces. Ionic forces due to salt and ice surface charge push this zone further down. Only after growing to a radius larger than 10 pm, will the ice particles eventually float toward the water surface in agreement with the simple intuition based on Archimedes' principle. Our result is the first prediction of observable repulsive van der Waals forces between ice particles and the water surface outside a laboratory setting. We posit that it has consequences on the biology of ice water as we predict an exclusion zone free of ice particles near the water surface which is sufficient to support the presence of bacteria.
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| 7. |
- Thiyam, Priyadarshini, et al.
(författare)
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Trends of CO2 adsorption on cellulose due to van der Waals forces
- 2015
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 470, s. 316-321
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Tidskriftsartikel (refereegranskat)abstract
- The non-retarded van der Waals and Casimir-Polder forces on a CO2 molecule in water near a single surface and between surfaces are explored. We observe preferential adsorption and desorption of CO2 molecules depending on the material of the surfaces. We also find a potential mechanism of capture and storage of CO2 molecules in a geometry consisting of a cellulose surface coated by a thin film of water and then by air.
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