PHYSICAL REVIEW FOCUS 15 January 2008 http://focus.aps.org/
David Ehrenstein, American Physical Society

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TO MERGE, DROPS MUST SEPARATE
Mixtures as varied as salad dressings and crude oil can contain
droplets of water in an oily solution. These droplets often merge
continuously, which can lead to "unmixing." Now researchers have
watched individual pairs of droplets coalescing in a new way. As
they report in the 18 January Physical Review Letters, the team was
surprised to find that droplet fusion occurs as the pair is
separating, rather than when they're pushing against each other. The
results may lead to a better understanding of the physics of unmixing
in similar mixtures that are important in many industries.
(Nicolas Bremand et al., Phys. Rev. Lett. 100, 024501)
COMPLETE Focus story at http://focus.aps.org/story/v21/st2