Enzymatic degradation of polylactic acid is studied experimentally and analytically. Gel permeation chromatography profiles obtained before and after the enzymatic degradation of polylactic acid (PLA) were introduced into the analysis based on a mathematical model. Previously developed techniques were successfully adapted to the analysis of an initial value problem consisting of an endogenous depolymerization model and an initial condition, and an inverse problem to determine the degradation rate for which the solution of the initial value problem also satisfies a final condition. Those problems were solved numerically and numerical results are introduced. Degradabilities of PLA and polyvinyl alcohol are compared.magnified image

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A Convenient Synthesis of Olefins via Deacylation Reaction. -Several α,β-unsaturated ketones, esters, and lactones are prepared by condensation of aldehydes with 1,3-dicarbonyl compounds in the presence of K2CO3. This deacylation reaction is found to be an alternative procedure to Wittig and Wittig-Horner reactions. The E/Z selectivity of the deacylation reaction depends on the α-substituents of the 1,3-dicarbonyl compounds. -(NAKATSU, S.; GUBAIDULLIN, A. T.; MAMEDOV, V. A.; TSUBOI*, S.; Tetrahedron 60 (2004) 10, 2337-2349; Dep. Environ. Chem. Mater., Fac. Environ. Sci. Technol., Okayama Univ., Tsushima, Okayama 700, Japan; Eng.) -Klein 28-065