The vessel may be oriented such that the external gradient acts in {HEAD ~ opposition} to, or in conjunction with, the influence of gravity upon {TAIL ~ the target material} 
The vessel may be oriented such that the external gradient acts in { HEAD ~ opposition } to , or in conjunction with , the influence of gravity upon { TAIL ~ the target material }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL