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31.
R. Costalat J. Blais J.-P. Ballini A. Moysan J. Cadet O. Chalvet P. Vigny 《Photochemistry and photobiology》1990,51(3):255-262
The 365 nm irradiation of thymine thin films in the presence of pyridopsoralens is shown to induce the formation of cyclobutane thymine dimers, in contrast to other compounds such as 8- and 5-methoxypsoralen. In order to elucidate the mechanism of such a photosensitized reaction, we have determined the energy of the lowest triplet state (T1) of these compounds, using phosphorescence spectroscopy and CNDO/S quantum chemistry calculations. The T1 energy values were found to be significantly higher for pyridopsoralens--up to 0.3 eV--than for 8- and 5-methoxypsoralen (approximately 2.8 eV), which are not able to photoinduce cyclobutane thymine dimers. The determination of the relative efficiency of cyclobutane thymine dimer formation was performed using chromatographic analysis. A good correlation was found between the energy of the T1 state of the psoralen derivatives and the related cyclobutane thymine dimer formation. Moreover, the photosensitized cyclobutane thymine dimer formation appeared to be temperature-dependent. Our results are consistent with a mechanism involving a triplet energy transfer from the pyridopsoralen to thymine. 相似文献
32.
The minerals mimetite Pb5(AsO4)3Cl, arsenian pyromorphite Pb5(PO4,AsO4)3Cl and hedyphane Pb3Ca2(AsO4)3Cl have been studied by Raman spectroscopy complimented with infrared spectroscopy. Mimetite is characterised by a band at 812–3 cm−1 attributed to the Ag mode. For the arsenian pyromorphite this band is observed at 818 cm−1 and for hedyphane at 819 cm−1. For mimetite and hedyphane bands at 788 and 765 cm−1 are attributed to Au and E1u vibrational modes and are both Raman and infrared active. For the arsenian pyromorphite, Raman bands at 917–1014 cm−1 are attributed to phosphate stretching vibrations. Raman spectroscopy clearly identifies bands attributable to isomorphous substitution of arsenate by phosphate. The observation of low intensity bands in the 3200–3550 cm−1 region are assigned to adsorbed water and OH units, thus indicating some replacement of chloride ions with hydroxyl ions. 相似文献
33.
Stephen W. Ayer Jocelyne Hellou Mark Tischler Raymond J. Andersen 《Tetrahedron letters》1984,25(2):141-144
Extracts of the dorid nudibranch contain the sesquiterpene nanaimoal (1). The structure of nanaimoal was inferred from its spectral data and the biogenetic isoprene rule. it was confirmed by an unambiguous synthesis of its p-bromophenyl-urethane derivative 10. 相似文献
34.
The carbon-carbon connectivity of terreinol, a new metabolite isolated from Aspergillus terreus, and its previous (13)C assignments were confirmed by a two-dimensional INADEQUATE experiment using a few milligrams of the compound with natural (13)C abundance. The carbon-carbon correlations were determined by computational analysis (with >99% probability) of this experiment. Additionally, the absolute configuration of terreinol was achieved indirectly via its corresponding secondary alcohol by the modified Mosher method allied to conformational analysis. The shielding effect of the phenyl group of methoxytrifluoromethylphenylacetic acid (MTPA) on the substituents of the carbonylic centre gave a fully regular Deltadelta(SR) sign distribution, allowing reliable assignment of the R configuration for terreinol. 相似文献
35.
Eric?Schmidlin Thierry?Wannier Jocelyne?Bloch Abderraouf?Belhaj-Saif Alexander?F?Wyss Eric?M?RouillerEmail author 《BMC neuroscience》2005,6(1):56
Background
After sub-total hemi-section of cervical cord at level C7/C8 in monkeys, the ipsilesional hand exhibited a paralysis for a couple of weeks, followed by incomplete recovery of manual dexterity, reaching a plateau after 40–50 days. Recently, we demonstrated that the level of the plateau was related to the size of the lesion and that progressive plastic changes of the motor map in the contralesional motor cortex, particularly the hand representation, took place following a comparable time course. The goal of the present study was to assess, in three macaque monkeys, whether the hand representation in the ipsilesional primary motor cortex (M1) was also affected by the cervical hemi-section. 相似文献36.
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38.
Yuanming Deng Julien Bernard Pierre Alcouffe Jocelyne Galy Lizong Dai Jean‐François Gérard 《Journal of polymer science. Part A, Polymer chemistry》2011,49(20):4343-4352
A series of well‐defined hybrid block copolymers PMACyPOSS‐b‐PMMA and PMAiBuPOSS‐b‐PMMA exhibiting high POSS weight contents have been synthesized by RAFT polymerization and further studied as modifiers for epoxy thermosets based on diglycidyl ether of bisphenol A. The hybrid block copolymers self‐assembled within the epoxy precursors into micelles possessing an inorganic core and a PMMA corona. Thanks to the presence of the PMMA blocks that remain miscible until the end of the reaction, curing of the resulting blends afforded nanostructured hybrid organic/inorganic networks with well‐dispersed inorganic‐rich nanodomains with diameters on the order of 20 nm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
39.
Yong-Gu Won Jocelyne Galy Jean-Pierre Pascault Jacques Verdu 《Journal of Polymer Science.Polymer Physics》1991,29(8):981-987
Stoichiometric, completely cured binary or ternary mixtures of the diglycidylether of bisphenol A (DGEBA), isophorone diamine (IPD), and trimethylcyclohexylamine (TMCA) monomers were studied by differential scanning calorimetry. The relations between the glass transition temperature Tg and the structure of the copolymer networks were investigated. Good predictions of Tg can be obtained on the basis of the following hypothesis: (1) the molar contributions MiT?1gi to the “copolymer effect” of difunctional groups are additive, (2) the crosslinking effect can be expressed by the DiMarzio relation in which the molar contribution of crosslink mers is an increasing function of the stiffness of linear segments. For the seven systems under study, the deviation between calculated and experimental Tg values is within experimental scatter. 相似文献
40.