How about a MOLECULAR sieve?
The Big Bang Theory Season 2, Episode 18
Don't rush it. We may be dealing
with befoulment on a MOLECULAR level.
The Big Bang Theory Season 6, Episode 9
...because we were attending a symposium
on MOLECULAR positronium?
The Big Bang Theory Season 1, Episode 10
...and look for the seminar
on MOLECULAR positronium, then...
The Big Bang Theory Season 1, Episode 10
...for that dense MOLECULAR cloud
of Aramis to dissipate.
The Big Bang Theory Season 1, Episode 3