The zirconia particles are prepared by {HEAD ~ a method} that includes {TAIL ~ two separate hydrothermal treatments} 
includes
The zirconia particles are prepared by { HEAD ~ a method } that includes { TAIL ~ two separate hydrothermal treatments }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL