Masonry oven India, tandoors are traditional clay ovens, although these days modern electrically fired tandoors are available. The open-topped tandoor is a transitional design between the earth oven and the Roman-plan masonry oven. In the precolumbian Americas, similar ovens were often made of clay or adobe and are now referred to by the Spanish term "horno" (meaning "oven"). Horns are also traditional in the American Southwest. The traditional direct-fired masonry design is often called a "Roman" or "black" oven and dates in Western culture to at least the Roman Republic. It is known as a black oven because the fire generates soot
Ceramic membrane gas separation. Examples are the separation of oxygen from air, or the separation of hydrogen gas from a mixture. Porous ceramic membranes are chiefly used for gas separation and micro- or nanofiltration. They can be made from both crystalline as well as amorphous solids. An example of an amorphous membrane is the silica membrane. An example of a highly porous membrane is the type made of silicon carbide. The first ceramic membranes were produced in France in the 1980s for the purpose of uranium enrichment in the nuclear industry. After many of the nuclear plants were set up in France