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