Since liquid crystals transmit only about 15% of any incident light, the black light absorbing material facilitates observation and {HEAD ~ measurement} of {TAIL ~ color changes} in the liquid crystal material against a dark background 
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Since liquid crystals transmit only about 15 % of any incident light , the black light absorbing material facilitates observation and { HEAD ~ measurement } of { TAIL ~ color changes } in the liquid crystal material against a dark background
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH