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