Nanoparticles are often seen as a new, man-made invention, but they have long existed in nature-salt from the sea and smoke from volcanoes can be found in the atmosphere in the form of nanoparticles. What interests materials scientists is that with modern processing techniques it is possible to turn many bulk materials into nanoparti-cles-measured asioo nanometres (billionth of a metre) or less. The reason for doing so is that nanoparticles can take on new or greatly enhanced properties because of quantum mechanics and other effects. This includes unique physical, chemical, mechanical and optical characteristics which are related to the particles' size. Engineers can capture some of those properties by incorporating nanoparticles into their materials.
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