{HEAD ~ The primary class} of compounds employed are ethylene oxide derivatives, {TAIL ~ nonionic polysaccharides} and under certain specified conditions anionic polysaccharides 
are
{ HEAD ~ The primary class } of compounds employed are ethylene oxide derivatives , { TAIL ~ nonionic polysaccharides } and under certain specified conditions anionic polysaccharides
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH