The 248 nm ablation of poly(methy1 methacrylate) (PMMA) doped with 5-diazo Meldrum's acid (DM) has been investigated by measurements of etch profile, transient absorption spectra, and transient absorbance at 248 nm. There were three fluence regions with respect to characteristic morphological changes of the polymer film; no morphological change, an elevation of the film surface (swelling), and etching were observed in the low, medium, and high fluence regions, respectively. The photodecomposition of DM into the ketene was confirmed by transient absorption spectroscopy, and its yield was determined to be 0.62. The results obtained by transient absorption spectroscopy made it possible to simulate the photodecomposition dynamics of DM, and the amounts of the absorbed energy and the photodecomposition products were estimated. On the basis of the obtained results, it is concluded that the amount of the absorbed energy governs ablation; namely, thermal processes are dominant although DM photodecomposes with a high quantum yield. The cyclic multiphotonic absorption by the ketene is discussed.

We have reported that the gene mph(C) (formally referred to as 'mphBM') is located on plasmid pMS97 342 bp downstream of the msr(A) gene. msr(A) specifies resistance to macrolides by ABC-transporter-mediated efflux, and mph(C) has 49% identity to the amino acid sequence of MPH(2P)II, which encodes a phosphotransferase that inactivates some macrolide antibiotics. A strain of Staphylococcus aureus NCTC8325 containing plasmid pMS97 inactivated unlabeled and 14 C-labeled erythromycin when tested by bioautographic and radioautographic techniques. In addition to erythromycin, other 14-membered ring macrolides (except for ketolides), 15-membered ring macrolides and 16-membered ring macrolides, mycinamicin, rosamicin and YM133, were inactivated by the strain. Erythromycin inactivation products produced by the strain carrying pMS97 were completely different from those produced by Escherichia coli BM694 bearing plasmid pAT63, which contains the ereA gene encoding an esterase that hydrolyzes macrolide lactones. Constructs formed with the msr(A) and mph(C) genes, and with the msr(A), mph(C) and erm(Y) genes, showed erythromycin-inactivating activity, but another construct built with the mph(C) gene alone failed to show such activity. This result suggests that any region of the msr(A) gene is needed for the expression of mph(C).

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