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