The material is chosen so that the dissolution of {HEAD ~ the binder} occurs at {TAIL ~ the desired rate} 
The material is chosen so that the dissolution of { HEAD ~ the binder } occurs at { TAIL ~ the desired rate }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL