{HEAD ~ The zirconia particles} are substantially non associated and have an average size no greater than 50 nanometers and may contain {TAIL ~ yttrium} 
contain
{ HEAD ~ The zirconia particles } are substantially non associated and have an average size no greater than 50 nanometers and may contain { TAIL ~ yttrium }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL