Estimation of the cholesterol percentages in mixtures arachidonic acid - cholesterol

摘要

Arachidonic acid (AA) samples and mixtures of arachidonic acid - cholesterol (AA -C) were manufactured and subjected to external electric and cw or pulsatory optical laser fields. The polarizing microscope showed a pseudohomeotropic smectic C texture for AA at 10°C and smectic C textures with fibers for mixtures AA -C at room temperature. The dependences I = I(U) at t°C C = const. and l = l(t) U = const. t being the time, showed that samples are dielectrics with a weak conduction (I～10{sup}(-9) A, U = (0 - 40V). Pure acid samples present an electric hysteresis, which disappears when cholesterol is added. The current occurred when the electric field is applied, decreases in time and tends to a constant value. When the temperature was 19°C, a cw focussed laser radiation from a He-Ne laser (λ = 632.8 nm, P = 20 mW) determined a lenslike effect in AA, but no effect in mixtures. At the same temperature the samples were crossed by some green pulses (λ = 532 nm, τ = 200μs) furnished by all experimental setup containing a Nd{sup}(3+) glass laser and KDP crystal for the second harmonic generation. The shape and extension of the pulse in the time domain, displayed on a sampling oscilloscope are some indications of the cholesterol percentage.