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" Phase-Change Incubator  Plug-in incubators used for culturing bacteria to diagnose disease and test water safety don&amp;#039;t work in locations that lack electricity. To create an inexpensive alternative, Smith identified a waxlike substance that melts when warmed and maintains a steady 98.6 F temperature as it changes from a liquid back to a solid. Her incubator can keep a sample at a precise temperature for more than 24 hours. Screenless Hammer Mill  It takes half an hour to grind 2.2 pounds of flour by hand--but only a minute using a hammer mill. Most designs rely on fragile, hard-to-replace screens to separate the flour from larger particles. Smith&amp;#039;s cheaper, more reliable version is screenless, using airflow generated by the spinning blades to separate the flour. (For one version, a leaf spring from an abandoned car became the grinding blade.) Automatic Chlorinator  When a Honduras community of 300 families needed a way to regulate the flow of chlorine to its water storage tank, a D-Lab team took inspiration from a toilet. Working with a village plumber, they built a device made from a fuel container for a reservoir, a clamp from an IV drip kit and a toilet float valve. The plumber later made improvements and installed the device in dozens of nearby communities. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/science/green-tech/a3384/4273679/>