{TAIL ~ The vessel} is then positioned in a holder on {HEAD ~ the perimeter} of a centrifuge rotor 
{ TAIL ~ The vessel } is then positioned in a holder on { HEAD ~ the perimeter } of a centrifuge rotor
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH