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WTRACT Unsaturated fatty acids arachidonicurn and elaidicwn acids with liquid crystal Sit properties were investigated. These aci4s have an important role in biologicel membrane.The electrical meastie' rements showed nonlinear dielectrical properties and ferroelectri.-city.Optical nonlinear behaviour, dependent on temperature, distance, cell thickness, incidence angle and incident optical laser po.-•wer was aimlised.Phe samplçs Were ittilised like nonlinear lens and in an all-optical bistable device.. 1JNTRQDUOTflRIn the last years, several optical devices using different liquid crystal (11c) configurations heve been proposed.An increasing interest in the use of yi as nonlinear optical media was observed.LO are highly nonlinear , Optical field .-induced molecular reori.-entation being significant, because of the strong molecular conelation. The director tilt or turn, a change in the dielectrical constant E determining.In a focused laser beam,the IC samples behaved like a convergent lens; this is en external self-focusing of the laser beam, after their passage through the C film.Like IC we have utilised some fatty acids,who are present in biological membranes ae such, or in some phospholipides bulBy optical microscopy, their mesomorphic state was emphasised ' .Generally, they Showed a SmC-type texture, with different characte-. ristic features. 2.DIELECTRICAL PROPERTI2SThe fatty acids we hsve investigated are the trachidonicum acid and the eleidicum acid. They present a thermotropic enantiotropical mesomórphism: the arachidonicurn acid h9s2a pseudohomeotropical smectic C-type1tetture between 4°C -202C ; the el8idicum acid has a smectic C ( with domains ) texture between 28 C -51°C. Thqee fatty acids exhibit electrical hysteresis and ferroelectricity'. The arachidonicum acid Is an unsaturated fatty acid (C20H,202) with four double chains at 5,8,11,14, present in biological 1 membranes, forerunner of some very important for human body substan-08794 0 W9-O/97/$4.X • SnVoL SEX Imwntln Optios ard Pin CafsqS Optlcs(7fl7)/ 3fl Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/22/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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