We investigated the bonding structures of thiophene molecules adsorbed on the Si(100)-2 × 1 surface at 300 K and its evolution upon annealing by employing core−level photoemission spectroscopy, near-edge X-ray absorption fine structure (NEXAFS), and ab initio calculations. The C 1s and S 2p core-level spectra measured at three different temperatures, 300, 350, and 400 K, are consistently interpreted in terms of the following structures suggested by theoretical calculations: the 2,3-and 2,5-dihydrothiophene (DHT), twisted 2,3-and 2,5-DHT, tetrahydrothiophene (THT), twisted THT, and the desulfurization and twisted desulfurization where the sulfur atom is dissociated from the thiophene ring. We find significantly enhanced desulfurization of thiophene molecules by mild thermal annealing, which is explained by new pathways between desulfurization and other structures.

We mixed various amounts of methotrexate with bone cement and measured the absorbance daily for 4 weeks. The cytotoxic effects on SaOS2 and MG63 osteosarcoma cells were examined by the MTT assay, and analysed according to the methotrexate concentration and the elapsed time. The amount of eluted methotrexate was greatest during the first day, and then decreased rapidly reaching a plateau in the third week. The number of viable tumour cells decreased significantly after 72 h, and they were hardly seen after 1 week. Résumé Nous avons étudiés le mélange de methotrexate avec du ciment à os à des concentrations variables et mesuré la diffusion journalière pendant quatre semaines. L'effet cytotoxique sur les cellules ostéosarcomateuses SaOS2 et MG63 a été examinés par l'essai MTT, et analysé d'après la concentration du méthotrexate et le temps écoulé. Le montant de méthotrexate relargué était plus grand pendant le premier jour, et a ensuite diminué pour arriver à un plateau dans la troisième semaine. Le nombre de cellules tumorales viables a diminué considérablement après 72 heures pour être presque nul après une semaine.

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