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