Such hydroxyl groups may be formed on {HEAD ~ the surfaces} of {TAIL ~ both organic and inorganic materials} 
of
Such hydroxyl groups may be formed on { HEAD ~ the surfaces } of { TAIL ~ both organic and inorganic materials }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL