A differential pressure is applied across the membrane after each step of {TAIL ~ reagent addition} to the membrane in order to remove {HEAD ~ excess reagent} from the membrane 
A differential pressure is applied across the membrane after each step of { TAIL ~ reagent addition } to the membrane in order to remove { HEAD ~ excess reagent } from the membrane
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH