947 research outputs found
Effect of polymer-polymer interactions on the surface tension of colloid-polymer mixtures
The density profile and surface tension for the interface of phase-separated
colloid-polymer mixtures have been studied in the framework of the square
gradient approximation for both ideal and interacting polymers in good solvent.
The calculations show that in the presence of polymer-polymer excluded volume
interactions the interfaces have lower widths and surface tensions compared to
the case of ideal polymers. These results are a direct consequence of the
shorter range and smaller depth of the depletion potential between colloidal
particles induced by interacting polymers.Comment: 12 pages, 5 figures, accepted for J. Chem. Phy
Solvation in atomic liquids: connection between Gaussian field theory and density functional theory
For the problem of molecular solvation, formulated as a liquid submitted to
the external potential field created by a molecular solute of arbitrary shape
dissolved in that solvent, we draw a connection between the Gaussian field
theory derived by David Chandler [Phys. Rev. E, 1993, 48, 2898] and classical
density functional theory. We show that Chandler's results concerning the
solvation of a hard core of arbitrary shape can be recovered by either
minimising a linearised HNC functional using an auxiliary Lagrange multiplier
field to impose a vanishing density inside the core, or by minimising this
functional directly outside the core --- indeed a simpler procedure. Those
equivalent approaches are compared to two other variants of DFT, either in the
HNC, or partially linearised HNC approximation, for the solvation of a
Lennard-Jones solute of increasing size in a Lennard-Jones solvent. Compared to
Monte-Carlo simulations, all those theories give acceptable results for the
inhomogeneous solvent structure, but are completely out-of-range for the
solvation free-energies. This can be fixed in DFT by adding a hard-sphere
bridge correction to the HNC functional.Comment: 14 pages, 4 figure
Disability-a chronic omission in health equity that must be central to Canada's post-pandemic recovery
As Canada begins to recover and learn from the COVID-19 pandemic, health equity and public health policies must be a central tenet of reform. Recent work has begun to provide guidance on an equitable pandemic recovery in Canada, which highlights many important groups that require specific consideration in recovery policies.1 There is a key omission in many of these guidelines and, in fact, most health equity efforts-people with disabilities
Jean-Pierre Hansen - a stimulating history of simulating fluids
International audienc
Molecular hydrodynamics from memory kernels
The memory kernel for a tagged particle in a fluid, computed from molecular dynamics simulations, decays algebraically as t−3/2. We show how the hydrodynamic Basset-Boussinesq force naturally emerges from this long-time tail and generalize the concept of hydrodynamic added mass. This mass term is negative in the present case of a molecular solute, which is at odds with incompressible hydrodynamics predictions. Lastly, we discuss the various contributions to the friction, the associated time scales, and the crossover between the molecular and hydrodynamic regimes upon increasing the solute radius
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