a hydrogen sensitive dye disposed in or placed on {TAIL ~ said container}, said hydrogen sensitive dye outputting {HEAD ~ a detectable signal} in response to a presence or absence of said molecular hydrogen 
a hydrogen sensitive dye disposed in or placed on { TAIL ~ said container } , said hydrogen sensitive dye outputting { HEAD ~ a detectable signal } in response to a presence or absence of said molecular hydrogen
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH