The metal may be in {HEAD ~ the form} of a particulate metal or atomically dispersed metal or {TAIL ~ both} 
of
The metal may be in { HEAD ~ the form } of a particulate metal or atomically dispersed metal or { TAIL ~ both }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL