Use
Particulates are solids or liquids in a subdividedstate. Because of this subdivision, particulatesexhibit special characteristics that are negligiblein the bulk material. Normally, particulates willexist only in the presence of another continuousphase, which may influence the properties ofthe particulates. A particulate may compriseseveral phases. They can be categorized intoparticulate systems that relate them to commonlyrecognized designations. Fine-particletechnology deals with particulate systems inwhich the particulate phase is subject to changeor motion. Particulate dispersions in solids havelimited and specialized properties and are conventionallytreated in disciplines other thanfine-particle technology. The universe is made up of particles, rangingin size from the huge masses in outer space— such as galaxies, stars, and planets — to theknown minute building blocks of matter —molecules, atoms, protons, neutrons, electrons,neutrinos, and so on. Fine-particle technologyis concerned with those particles that are tangibleto human senses, yet small compared tothe human environment — particles that arelarger than molecules but smaller than gravel.Fine particles are in abundance in nature (as inrain, soil, sand, minerals, dust, pollen, bacteria,and viruses) and in industry (as in paint pigments,insecticides, powdered milk, soap, powder,cosmetics, and inks). Particulates areinvolved in such undesirable forms as fumes,fly ash, dust, and smog and in military strategyin the form of signal flares, biological andchemical warfare, explosives, and rocket fuels.