Yet another known method uses {HEAD ~ a thermal gradient} to ensure {TAIL ~ selective adherence} of the lens in the mold 
to ensure
Yet another known method uses { HEAD ~ a thermal gradient } to ensure { TAIL ~ selective adherence } of the lens in the mold
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH