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21.
Tutusaus O Viñas C Núñez R Teixidor F Demonceau A Delfosse S Noels AF Mata I Molins E 《Journal of the American Chemical Society》2003,125(39):11830-11831
exo-Cluster dicarbollides substitution has allowed tuning of the E degrees (Ru(II)/Ru(III)) potential to obtain the best-performing Kharasch catalyst. We postulate that this is possible through the to-and-fro electron movement between the boron cluster and the sulfonium moieties. 相似文献
22.
The peptide hormone adrenocorticotropin and a related peptide were studied in solution and in interaction with a model system of membranes (small unilamellar vesicles of dipalmitoylphosphatidylcholine and 17% dimyristoylphosphatidylglycerol) via fluorescence spectroscopy. In aqueous solution, intramolecular distances between the fluorescent residues R(Tyr2-Trp9) = 9.2 Å and R(Trp9-Tyr23) 18 Å were obtained, in agreement with molecular models. Interaction of the peptide with the negatively charged membrane is evident from the alteration of the Trp photophysical parameters (quantum yield, fluorescence spectra and anisotropy), with a partition constant between the lipidic and aqueous phase of Kp =1–2 times 103. The existence of two populations of Trp in the membrane, which are distinctly accessed by acrylamide, was concluded from the tryptophan fluorescence quenching study; the two fractions are located near the membrane interface as inferred from its fluorescence quenching by the 5-doxylstearate and 16-doxylstearate lipophilic quenchers. This result is further supported by energy transfer experiments to the 3-(9-anthroyloxyl)stearic acid and 12-(9-anthroyloxyl)stearic acid probes. 相似文献
23.
A method based on headspace solid-phase microextraction-gas chromatography-mass spectrometry is proposed for the quality control of multilayer packaging and its manufacturing process. Volatile organic compounds (VOCs) are produced in the manufacturing process of the packaging. They can cause organoleptic problems or modify the properties of the packaging depending on the nature and the amount of the VOCs formed. The quantification using packaging samples with a known VOC concentration for the calibration is proposed in order to reduce the analysis time, and the method is validated using a statistical test. Finally, the method is applied to the determination of odour-responsible compounds in multilayer packaging samples obtained under different extrusion-coating conditions, i.e. type of extruder, type of polymer and extrusion speed. 相似文献
24.
Borasio M Rodríguez de la Fuente O Rupprechter G Freund HJ 《The journal of physical chemistry. B》2005,109(38):17791-17794
Methanol decomposition and oxidation on Pd(111) at millibar pressure were studied by in situ polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS), on-line gas chromatography and pre- and postreaction X-ray photoelectron spectroscopy (XPS). Various dehydrogenation products such as methoxy CH3O, formaldehyde CH2O, formyl CHO, and CO could be spectroscopically identified. Methanol oxidation proceeds via dehydrogenation to formaldehyde CH2O, which either desorbs or is further dehydrogenated to CO, which is subsequently oxidized to CO2. Carbonaceous overlayers that are present during the reaction may favorably affect the selectivity toward CH2O. The reaction takes place on metallic Pd, and no indications of an involvement of Pd surface oxide were observed. 相似文献
25.
Studies about the development of a new effective aromatization process for converting gasoline rich in light saturated hydrocarbons, using modified molecular shapeselective zeolites, have been carried out. Naphthas with olefins and naphthenes are potential feedstocks. The yield of aromatic hydrocarbons increases with decreasing hydrogen content of the feed. Zn-SABO and Zn-ZSM type zeolites have been shown to be excellent catalysts for the process. 相似文献
26.
de Namor AF Chahine S Castellano EE Piro OE Jenkins HD 《Chemical communications (Cambridge, England)》2005,(30):3844-3846
An additive thermodynamic contribution of pendant arms to the complexation of calixarene derivatives with mercury(II) in acetonitrile is for the first time demonstrated. 相似文献
27.
Oscar H. Will III Natalie A. Newland Kaylan L. Blelville 《Photochemistry and photobiology》1985,41(3):283-287
Abstract— Exposure of variously pigmented strains of Ustilago violacea to high intensity incandescent radiation resulted in the generation of three types of survival curves. High carotene, low cytochrome c containing strains of U. violacea were generally characterized by linear type I survival curves with slopes approximately equal to zero. Strains which lacked carotenes were characterized by exponential decay type II survival curves. A third survival curve, type III was observed with carotene accumulating strains which also contained large amounts of cytochrome c. The type III curves are characterized by an initial loss of viability, similar to the type II curves, followed by a recovery period, with eventual stability in survival. The survival curve type appears to be dependent on the relative mg quantities of cytochrome c and carotenes in the cells. Strains with carotene/cytochromec ratios of0–1 × 10-1 ,3–15× 10-1 and l6 × 10-1 and above had type II, type III and type I survival curves, respectively. 相似文献
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