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