Factors affecting ordered chain packing

Another factor affecting the lifetime of a membrane fluorophore probe is its proximity to the surface. The lifetimes of the DPH, DPH-phosphatidyl-choline (DPH-PC), and trimethylammonium-DPH (TMA-DPH) probes decrease in the order DPH > DPH-PC > TMA-DPH, as the probe locates nearer to the surface of the lipid bilayer.(7) The same is found for the anthroyl-stearate probes.(8) More recently, it has been shown that with TMA-DPH, the lifetime appears to be fairly sensitive to the differences in lipid bilayer packing induced by differing degrees of unsaturation in the phospholipid fatty acyl chains.(9) This aspect of the use of TMA-DPH and possibly other probes remains to be further exploited. 

Class 2. Characteristics (i) the decomposition may deviate from first-order kinetics and/or there are often marked induction periods (i7) the rate is substantially reduced by the addition of propene, cyclohexene, toluene, or other radical-chain inhibitors, and may be affected by packing the reaction vessel Hi) the Arrhenius preexponential factor may differ significantly from 10 sec . This behaviour is consistent with the presence of radical-chains. Reactions in this class... 

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