Boron nitride aerogel is an aerogel made of highly porous BN. Yttria is used as a sintering additive in the production of porous silicon nitride. The effective diffusion coefficient describes diffusion through the pore space of porous media. Such multiple surfaces are abundant in batting and porous foam. Solid pyrophoric payloads are based on iron platelets coated with a porous aluminium layer. Refractories are inorganic, nonmetallic, porous, and heterogeneous. Oligochaetes are also abundant in areas supporting porous and spongy layers of algal mat. A sponge is a tool or cleaning aid made of soft, porous material. Paper based microfluidics rely on the phenomenon of capillary penetration in porous media. Assume that some liquid is poured on top of some porous material. The interdental plates of the maxilla were thin, fused, porous, and triangular. Natural gas may be stored by adsorbing it to the porous solids called sorbents. Networks defined in fracture systems and porous substances have demonstrated these characteristics. This simpler version dispensed with the porous barrier. Enamel also becomes less porous and phosphate deficient.