{HEAD ~ A method} 1 wherein {TAIL ~ the oxygen content} of the gas is from about 1% to about 100% 
wherein
{ HEAD ~ A method } 1 wherein { TAIL ~ the oxygen content } of the gas is from about 1 % to about 100 %
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH