Derek Y. C. Chan

Learn More
In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits(More)
The phase behavior of charged colloidal systems has been studied recently by the density functional theory formalism (DFT) [R. van Roij, M. Dijkstra, and J. P. Hansen, Phys. Rev. E 59, 2010 (1999)]. A key feature of this approach is the appearance of a density and temperature-dependent effective Hamiltonian between the charged colloids. Under certain(More)
Pendant drop tensiometry offers a simple and elegant solution to determining surface and interfacial tension - a central parameter in many colloidal systems including emulsions, foams and wetting phenomena. The technique involves the acquisition of a silhouette of an axisymmetric fluid droplet, and iterative fitting of the Young-Laplace equation that(More)
We introduce a lateral atomic force microscopy (AFM) method to measure the hydrodynamic drag force acting on a microscopic emulsion droplet moving parallel to a flat surface. A tetradecane oil droplet formed in an aqueous solution of sodium dodecylsulfate was attached to a V-shaped atomic force microscopy cantilever, and lateral hydrodynamic interactions(More)
Over the past decade, direct force measurements using the Atomic Force Microscope (AFM) have been extended to study non-equilibrium interactions. Perhaps the more scientifically interesting and technically challenging of such studies involved deformable drops and bubbles in relative motion. The scientific interest stems from the rich complexity that arises(More)
Models of surfaces with intrinsic ionisable amphoteric surface sites governed by the dissociation of acid-base potential determining ion species together with the capacity for the adsorption of anion and cations of the supporting electrolyte are required to describe both the results of electrokinetic and titration measurements of inorganic oxides. The(More)
We present a method of parallelizing flat histogram Monte Carlo simulations, which give the free energy of a molecular system as an output. In the serial version, a constant probability distribution, as a function of any system parameter, is calculated by updating an external potential that is added to the system Hamiltonian. This external potential is(More)
The hydrophobic attraction describes the well-known tendency for nonpolar molecules and surfaces to agglomerate in water, controlled by the reorganization of intervening water molecules to minimize disruption to their hydrogen bonding network. Measurements of the attraction between chemically hydrophobised solid surfaces have reported ranges varying from(More)
The interaction between moving bubbles, vapor voids in liquid, can arguably represent the simplest dynamical system in continuum mechanics as only a liquid and its vapor phase are involved. Surprisingly, and perhaps because of the ephemeral nature of bubbles, there has been no direct measurement of the time-dependent force between colliding bubbles which(More)
Large interconnected gold wire structures ( approximately cm;{2}) of different topologies have been made by the drying of a gold nanoparticle suspension that has formed a connected network of liquid bridges in the interstices between a 2D crystalline layer of latex particles and a substrate. Slow evaporation of the suspending medium assembles the(More)