{HEAD ~ The flows} of all of the reactant gases are then terminated and the tube is flushed out with {TAIL ~ dry nitrogen} flowed into it through one of the injectors 
{ HEAD ~ The flows } of all of the reactant gases are then terminated and the tube is flushed out with { TAIL ~ dry nitrogen } flowed into it through one of the injectors
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH 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 OTH