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