This means that substantially all the catalyst provided in the cell wall 23 can contribute to {HEAD ~ conversion reaction} of {TAIL ~ exhaust gas} 
This means that substantially all the catalyst provided in the cell wall 23 can contribute to { HEAD ~ conversion reaction } of { TAIL ~ exhaust gas }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL