In the course of attempts to characterise this new principle, {HEAD ~ many hundreds} of {TAIL ~ materials} have been screened and hundreds of formulations made by blending these materials have been examined 
of
In the course of attempts to characterise this new principle , { HEAD ~ many hundreds } of { TAIL ~ materials } have been screened and hundreds of formulations made by blending these materials have been examined
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH