Peptide surfactants (Pepfactants) for switchable foams and emulsions

We have developed a series of sustainable peptide surfactants (Pepfactants) capable of stabilizing foams and emulsions in a stimuli-responsive manner, based on the reversible formation of a mechanically strong interfacial film. Under conditions where the interfacially adsorbed peptide forms a mechanically strong film state, foam or emulsion stabilization occurs as a direct result of the film strength. Under conditions where the interfacially adsorbed peptide forms a mobile detergent state, foam or emulsion stabilization is either reduced, or does not occur. Preformed foams or emulsions stabilized by Pepfactants undergo rapid phase coalescence when the film state is converted to the detergent state. Switching between film and detergent states is readily and reversibly achieved by a change in the bulk solution composition, such as a change in pH, or the addition or sequestering of metal ions. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

NGC922 - a New Drop-through Ring Galaxy

We have found the peculiar galaxy NGC 922 to be a new drop-through ring galaxy using multiwavelength (ultraviolet-radio) imaging and spectroscopic observations. Its 'C'-shaped morphology and tidal plume indicate a recent strong interaction with its companion which was identified with these observations. Using numerical simulations we demonstrate that the main properties of the system can be generated by a high-speed off-axis drop-through collision of a small galaxy with a larger disc system, thus making NGC 922 one of the nearest known collisional ring galaxies. While these systems are rare in the local Universe, recent deep Hubble Space Telescope images suggest they were more common in the early Universe.