Triezenberg-Zwanzig expression for the surface tension of a liquid drop

Formulas, analogous to the Triezenberg-Zwanzig expression for the surface tension of a planar interface, are presented for the Tolman length, the bending rigidity, and the rigidity constant associated with Gaussian curvature. These expressions feature the Ornstein-Zernike direct correlation function and are derived from considering the deformation of a liquid drop in the presence of an external field. This approach is in line with the original analysis by Yvon [in Proceedings of the IUPAP Symposium on Thermodynamics, Brussels, 1948]. It is shown that our expressions reduce to previous results from density functional theory when a mean-field approximation is made for the direct correlation function. We stress the importance of the form of the external field used and show how the values of the rigidity constants depend on itSupramolecular & Biomaterials Chemistr

Comment on "Effect of gravity on contact angle: a theoretical investigation"

Supramolecular & Biomaterials Chemistr

Nucleation of Wetting Layers

Supramolecular & Biomaterials Chemistr

Helfrich free energy for aggregation and adhesion

Supramolecular & Biomaterials Chemistr

On the determination of the structure and tension of the interface between a fluid and a curved hard wall

Supramolecular & Biomaterials Chemistr

Fusion Pores Live on the Edge.

Biological transmission of vesicular content occurs by opening of a fusion pore. Recent experimental observations have illustrated that fusion pores between vesicles that are docked by an extended flat contact zone are located at the edge (vertex) of this zone. We modeled this experimentally observed scenario by coarse-grained molecular simulations and elastic theory. This revealed that fusion pores experience a direct attraction toward the vertex. The size adopted by the resulting vertex pore strongly depends on the apparent contact angle between the adhered vesicles even in the absence of membrane surface tension. Larger contact angles substantially increase the equilibrium size of the vertex pore. Because the cellular membrane fusion machinery actively docks membranes, it facilitates a collective expansion of the contact zone and increases the contact angle. In this way, the fusion machinery can drive expansion of the fusion pore by free energy equivalents of multiple tens of k <sub>B</sub> T from a distance and not only through the fusion proteins that reside within the fusion pore

Wetting and drying transitions in mean-field theory: describing the surface parameters for the theory of Nakanishi and Fisher in terms of a microscopic model

The theory of Nakanishi and Fisher [Phys. Rev. Lett. 49, 1565 (1982)] describes the wetting behavior of a liquid and vapor phase in contact with a substrate in terms of the surface chemical potential h(1) and the surface enhancement parameter g. Using density functional theory, we derive molecular expressions for h(1) and g and compare with earlier expressions derived from Landau lattice mean-field theory. The molecular expressions are applied to compare with results from density functional theory for a square-gradient fluid in a square-well fluid-substrate potential and with molecular dynamics simulations.Supramolecular & Biomaterials Chemistr

Microscopic Expressions for the Rigidity Constants of a Simple Liquid-Vapor Interface

Supramolecular & Biomaterials Chemistr

Rigidity constants from mean-field models

The interfacial tension of the planar interface and rigidity constants are determined for a simple liquid–vapor interface by means of a lattice-gas model. They are compared with results from the van der Waals model and from an analytical expansion around the critical point. The three approaches are in agreement in the regions where these theories apply.Supramolecular & Biomaterials Chemistr

Pressure Tensor of a Spherical Interface

In this paper we show how the use of the Irving–Kirkwood expression for the pressure tensor leads to expressions for the pressure difference, the surface tension of the flat interface, and the Tolman length which agree with the expressions found using microscopic sum rules. The use of the Schofield–Henderson expression for the pressure tensor for a particular contour different from the contour that leads to the Irving–Kirkwood expression is found to give incorrect results for the pressure difference and, in particular, also for the Tolman length. The distance between the so‐called mechanical surface of tension and the Gibbs dividing surface is found not to be given by Tolman’s length. Using an approximate expression for the pair density it is possible to find values for the location of the mechanical surface of tension and for Tolman’s length which are in reasonably good agreement with values found by Nijmeijer et al. in molecular dynamics simulations.Supramolecular & Biomaterials Chemistr