{HEAD ~ The sonication duration} is {TAIL ~ less than 15 minutes}, preferably less than 6 minutes more preferably 60 seconds or less 
is
{ HEAD ~ The sonication duration } is { TAIL ~ less than 15 minutes } , preferably less than 6 minutes more preferably 60 seconds or less
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH