Cyclic lactones having {HEAD ~ a closed ring structure} containing {TAIL ~ six members} can also be employed, if desired, such as lactide or glycolide 
Cyclic lactones having { HEAD ~ a closed ring structure } containing { TAIL ~ six members } can also be employed , if desired , such as lactide or glycolide
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH