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