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