| http://www.w3.org/ns/prov#value | - A suitable pore size of the microporous membrane is smaller than the retaining particle size of glass fiber filter, and is 0.2 ??m or more, preferably about 0.3 to 5 ??m, more preferably about 0.5 to 4.5 ??m, particularly preferably about 1 to 3 ??m.
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