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