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STEM Science and Engineering Saturday Seminar : Colloids and Emulsions. Anthony (Tony) Dinsmore Associate Professor of Physics University of Massachusetts Amherst Hasbrouck 411 666 North Pleasant St. Amherst, MA 01003 413-545-3786 E-mail: dinsmore@physics.umass.edu.
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STEM Science and Engineering Saturday Seminar: Colloids and Emulsions. Anthony (Tony) Dinsmore Associate Professor of Physics University of Massachusetts Amherst Hasbrouck 411 666 North Pleasant St. Amherst, MA 01003 413-545-3786 E-mail: dinsmore@physics.umass.edu The research shown here was supported by the National Science Foundation through grants DMR-0907195 and CBET-0967620. Feb 12., 2011. UMass Amherst
Eucerin skin cream in an optical microscope Size scale: approximately 0.4 mm (400 microns) across the image. The diameter of the big blob near the center (probably a liquid droplet) is similar in size to the diameter of a hair.
Wet Latex paint in an optical microscope The paint color is “Sag Harbor Gray,” but the image is grayscale.
Figure 1 | Meniscus climbing by the water treader Mesovelia. Figure 2 | Meniscus climbing by the larva of the waterlily leaf beetle. (Movies are included with the article!)
Shape can be described mathematically as a logarithm height Ln(x)
Half-and-half seen in an optical microscope(Homogenized and Pasteurized) Brownian motion/diffusion is visible here and can also be seen by light scattering.
(Charlie Chaplin demonstrates Brownian motion – something like the chaotic dance of molecules)
Colloidal Crystals Naturally occurring: http://www.theimage.com/gemstone/opal/opal.html Made in a laboratory: Murray & Sanders, Philos. Mag. A42, 721 (1980). Jiang et al, Chem. Mater.11, 2132 (1999).
Watching crystals form These crystals are composed of spheres that are vastly bigger than individual molecules, but the process by which they crystallize is very similar. (And it can be seen in a microscope!) The spheres attract one another when they come close. Water, salt, and surfactant (soap) are present too, but not seen in the images. A crystal of atoms would move MUCH faster and this process would be completed in approximately 0.00000000001 seconds! (That’s 10 picoseconds.) (John Savage and A. D.)
Experiments with the Bubble Model of a Metal Structure Sir Lawrence Bragg, W. M. Lomer, and J. F. Nye (1954)