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261.
III-V semiconductor compound structures are widely applied in technology of advanced microelectronics, optoelectronics, and gas sensors. In this paper, we report on the use of XPS to characterize in situ the interaction of thermally activated hydrogen atoms and hydrogen molecules with InP(1 0 0) surfaces covered by thin InN overlayers. XPS spectra were taken with an ESCALAB-210 spectrometer after repeated hydrogenation cycles at temperatures up to 350 °C. The evolution of the In 3d, In 4d, P 2p, N 1s, O 1s and C 1s photoelectron spectra was carefully monitored. The XPS spectra of the hydrogen exposed surface revealed significant differences compared to those from the non-hydrogenated surface. InN films were found to be weakly reactive to hydrogen under experimental conditions explored. The behavior of P atoms at the hydrogenated surface was dependent on the parameters characterizing each hydrogenation (exposure, hydrogen species used, annealing temperature). Moreover, the heavily hydrogenated surface exhibited a phosphorus enrichment. 相似文献
262.
5-episinuleptolide (1) is an abundant norcembranolide diterpene isolated from several species of the soft coral genus Sinularia. Biocatalytic transformation studies of 1 using Streptomyces lavendulea ATCC 8664 resulted in the isolation and characterization of two new metabolites 2 and 3. Compound 2, 6alpha-hydroxy-5-episinuleptolide was produced via a stereoselective reduction of 1 and was further metabolized into compound 3 which has a 3,8-bicylized cembranoid skeleton. The structures and configurations of the metabolites were determined by spectroscopic and X-ray crystallographic analyses. 相似文献
263.
N. Khalifa B. Yacoubi I. Attar A. Bardaoui R. Chtourou 《Colloid and polymer science》2013,291(11):2705-2709
In this work, we study the inclusion mechanism of Fe3+ ions in a polyvinyl alcohol (PVA) matrix. Thin films of pure and FeCl3-doped PVA on silicon substrates, prepared by the spin-coating method, are investigated using spectroscopic ellipsometry (SE) and Fourier transform infrared (FT-IR) spectroscopy. SE measurements of PVA and Fe3+-doped thin films are carried out at an incidence angle of 75° over the wavelength range of 0.24–1.1 μm. An optical model is used to obtain the refractive index (n) and the extinction coefficient (k). The gap energy E g is afterwards evaluated. The Fe3+ doping is found to affect strongly the optical parameters of the polymer films. In fact, an increase in the refractive index with doping is observed, resulting from the intermolecular hydrogen bonding between Fe3+ ions with the adjacent OH group of PVA. The increase of the thin films' absorption with doping is estimated by the k spectral profile analysis. The gap energy is then calculated and shows an important decrease with the Fe3+ filling, more pronounced for low doped samples. Such a behavior is confirmed by FT-IR analysis. 相似文献
264.
Nagy M. Khalifa Mostafa M. Ramla Abd El-Galil E. Amr Mohamed M. Abdulla 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):3046-3062
A series of some new acetylated S-glycosides of pyridine-2-thione derivatives, including D-glucose, D-galactose, D-xylose and L-arabinose derivatives were synthesized. Oxidation of some formed S-glycosides derivatives with H2O2 afforded the corresponding sulfones. S-Alkylation of pyridine-2-thione derivatives was performed to furnish the S-acyclo deazauridine derivatives. The entire tested compound showed potent anti-inflammatory activity were potent against edema and in the same time inhibited the prostaglandine formation. It is work mention that all the tested compounds showed high safety margin. The structures of the new synthesized compounds have been proved by IR, 1 HNMR, mass spectra and elemental analysis. 相似文献
265.
Hesham Fahmy Jordan K. Zjawiony Sherief Khalifa Frank R. Fronczek 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o85-o87
The title molecule, 2(R)‐[(1E,3E,7S,8S,11E,13R)‐13‐hydroxy‐4,8,12‐trimethyl‐7,8‐epoxycyclotetradeca‐1,3,11‐trien‐1‐yl]propane‐1,2‐diol, C20H32O4, is a semi‐synthetic analog of sarcophine, the natural cembranoid of marine origin, isolated from the soft coral Sarcophyton glaucum. The conformation of the 14‐membered ring differs substantially from that of sarcophine. The two OH groups of the propane‐1,2‐diol moiety form an unusual weak intramolecular hydrogen bond with an O⋯O distance of 2.788 (2) Å, and the molecules are linked into double chains by intermolecular hydrogen bonds with O⋯O distances of 2.772 (2) and 2.849 (2) Å. 相似文献