BIO 202 Lecture Notes - Lecture 15: Aerogel, Rayleigh Scattering, Knee Replacement
14 Nov 2018
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Problem set #2(11/29/17: samuel kistler"s discovery of and investigation of aerogels stemmed solely from his curiosity about jelly, which appropriately matched his transition from being a farmer to a chemist. Kistler"s experiments were used to determine whether the invisible gelatin mesh within jelly was an independent internal skeleton. Kistler show us that the liquid in jelly is connected throughout and replaced with other liquids. As such, all gelatin-like materials, including aerogels would share this characteristic. The jelly was placed in a closed autoclave which enabled for an increase in temperature without collapsing the internal skeleton. When the critical temp. is passed, the while liquid becomes a gas without evaporating, and under the pressure of the autoclave, the gas cannot escape. The fragile internal skeletons were replaced with a more rigid material known as silicon dioxide: silica aerogel had useful properties such as raleigh scattering, which enabled for a low degree of light distortion, and effective thermal insulation.
