A shutter system could then be used to physically separate the non affected molecules taking advantage of {HEAD ~ this difference} in {TAIL ~ velocity} 
in
A shutter system could then be used to physically separate the non affected molecules taking advantage of { HEAD ~ this difference } in { TAIL ~ velocity }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL