The gas used in {HEAD ~ the present invention} should contain {TAIL ~ at least about 70 mol percent hydrogen} 
The gas used in { HEAD ~ the present invention } should contain { TAIL ~ at least about 70 mol percent hydrogen }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL