Still hungry after finishing a snack? Now you can eat the wrapper. Researchers at the US Agricultural Research Service in Wyndmoor, Pennsylvania, have made edible film by mixing the milk protein casein with water and glycerol, a sugary by-product of biofuel production. Peggy Tomasula used supercritical carbon dioxide as a solvent to extract the casein from milk and blend the ingredients together.
Gadgets could soon run on miniature acoustic heat engines. These devices conduct heat to a surface that warms the air around it. The movement of hot air generates a high-frequency sound wave that in turn vibrates a piezoelectric electrode, producing a voltage. Now Orest Symko at the University of Utah in Salt Lake City has built the smallest ever acoustic heat engine, at 1.8 millimetres wide.
