Masonry oven more common as accessory features of a masonry heater. A compromise design known as the gueulard in France combines aspects of both internal and external-fired models. Masonry ovens remain popular in part because of the way their use affects cooking processes and food flavor. Where modern gas or electric ovens cook food by moving hot air around inside an insulated, lightweight box, a masonry oven works by soaking up heat, like a battery building up a full charge. When hot, the heavy oven walls release the heat slowly, for hours. Thus the food is cooked not only by hot air,
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