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Phenacyl esters of fatty acids have been formed In an essentially quantitative manner using crown ethers as catalysts. These esters absorb UV radiation strongly at 254 nm, allowing the detection of as small a quantity as 1 ng of C2 acid, and 50 ng of C20 acid. The method of synthesis is inexpensive and can be carried out in virtually any aprotic solvent system in a short period of time. Reaction conditions do not require total exclusion of water, thus simplifying the procedure. Liquid chromatographic separations of these esters have been obtained on a 25-cm long column packed with Cg bonded phase. The implications and uses of such a broad ranging synthesis are discussed.Several reasons can be given for the use of derivatization in chromatography: e.g., to enhance solute volatility (GC), to enhance separation, and to enhance detectability. The selection of a derivative can often become much more difficult than the actual derivatization itself. In all areas of

We consider an experiment in which a rectangular flat plate is flapped with two degrees of freedom, and a genetic algorithm tunes its trajectory parameters so as to achieve maximum average lift force, thus evolving a population of trajectories all yielding optimal lift forces. We cluster the converged population by defining a dynamical formation number for a flapping flat plate, thus showing that optimal unsteady force generation is linked to the formation of a leading-edge vortex with maximum circulation. Force and digital particle image velocimetry measurements confirm this result.

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