| http://www.w3.org/ns/prov#value | - In the two pairs of the pivots and the pivot bearings disposed at the upper and lower ends of the rotation shaft 19 of the impeller 1, at least one part of each pair should preferably be made of ceramics, such as alumina, zirconia, silicon carbide or silicon nitride, being superior in resistance against thrombus and friction.
|
