Tympanic membrane retraction adherent to other structures within the middle ear. Some retractions continue to progress and grow more deeply into the ear. This can result in erosion of bone. As the middle ear is only a narrow space, the eardrum only has to retract a short distance before it touches boney structures within the middle ear such as the ossicles. It may become adherent to these bones and in some cases, this contact leads to erosion of the bone. As well as ossicular erosion, the bone of the ear canal (e.g. the scutum) and even bone over the cochlea (the promontory) can
Membrane technology utilized for gas separations (removal of CO from natural gas, separating N from air, organic vapor removal from air or a nitrogen stream) and sometimes in membrane distillation. The later process helps in the separation of azeotropic compositions reducing the costs of distillation processes. The pore sizes of technical membranes are specified differently depending on the manufacturer. One common distinction is by "nominal pore size". It describes the maximum pore size distribution and gives only vague information about the retention capacity of a membrane. The exclusion limit or "cut-off" of the membrane is usually specified in the form of "NMWC"