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