| 摘要 |
A vented flask cap having a body portion with proximal and distal ends with a generally cylindrical sidewall extending from the proximal end to the distal end of first and second support plates are formed at the proximal end of the body portion and having a plurality of apertures extending therethrough; a filter assembly is also provided which includes a first, lower membrane having a first porosity, a second, upper membrane having a second porosity and a radiation absorbing material disposed between the first and second membranes.
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