{HEAD ~ The fluid} containing the photosensitizer may be flowed into {TAIL ~ a photopermeable container} for irradiation 
flowed into
{ HEAD ~ The fluid } containing the photosensitizer may be flowed into { TAIL ~ a photopermeable container } for irradiation
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH