A small hole is formed within {HEAD ~ each portion} of {TAIL ~ the exposed membrane} so that a differential pressure can be applied across the membrane without collapsing the membrane pores while effecting passage of liquid through the membrane 
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A small hole is formed within { HEAD ~ each portion } of { TAIL ~ the exposed membrane } so that a differential pressure can be applied across the membrane without collapsing the membrane pores while effecting passage of liquid through the membrane
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH