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11.
The energy level alignment between C60 and Al has been investigated by using ultraviolet photoelectron spectroscopy. To obtain the interfacial electronic structure between C60 and Al, C60 was deposited on a clean Al substrate in a stepwise manner. The valence-band spectra were measured immediately after each step of C60 deposition without breaking the vacuum. The measured onset of the highest occupied molecular orbital energy level was located at 1.59 eV from the Fermi level of Al. The vacuum level was shifted 0.68 eV toward lower binding energy with additional C60 layers. The observed vacuum level shift means that the interface dipole exists at the interface between C60 and Al. The barrier height of electron injection from Al to C60 is 0.11 eV, which is smaller value than that of hole injection. 相似文献
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The 4-bromomethyl-7-methoxycoumarin derivatives of 14 saturated and unsaturated fatty acids, including the omega-3 fatty acids, were separated by reversed-phase liquid chromatography and detected by laser-induced fluorescence. Baseline resolution was obtained by using a high-efficiency packed capillary column with 240,000 theoretical plates, together with a systematic optimization of the mobile phase composition. The retention indices of the fatty acid derivatives correlated well with a predictive empirical model, showing accuracy better than 0.46% relative error and reproducibility better than +/- 0.1% relative standard deviation. The physiologically important fatty acids with 12-22 carbon atoms and 0-6 double bonds were determined at the femtomole level in fish oil dietary supplements by using this methodology. 相似文献
14.
A fast and matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) compatible protein staining method in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1- and 2-D SDS-PAGE) is described. It is based on the counterion dye staining method that employs oppositely charged two dyes, zincon (ZC) and ethyl violet (EV) to form an ion-pair complex. The protocol, including fixing, staining and quick washing steps, can be completed in 1-1.5 h depending upon gel thickness. It has a sensitivity of 4-8 ng, comparable to that of colloidal Coomassie Brilliant Blue G (CBBG) staining with phosphoric acid in the staining solution. The counterion dye stain does not induce protein modifications that complicate interpretation of peptide mapping data from MS. Considering the speed, sensitivity and compatibility with MS, the counterion dye stain may be more practical than any other dye-based protein stains for routine proteomic researches. 相似文献
15.
A background-free, fast protein staining method in polyacrylamide gel electrophoresis using an acidic dye, zincon (ZC) and a basic dye, ethyl violet (EV) is described. It is based on the counterion dye staining technique that employs two oppositely charged dyes to form an ion-pair complex in staining solution. The selective binding of free dye molecules to proteins in acidic solution produces bluish violet-colored bands. It is a rapid and end-point staining procedure, involving only fixing and staining steps that are completed in 1-1.5 h. The detection limit of this method is 8-15 ng of protein that is comparable to the sensitivity of the colloidal Coomassie Brilliant Blue G (CBBG) stain. Due to its sensitivity and speed, this stain may be more practical than any other dye-based stains for routine laboratory purposes. 相似文献
16.
Characterization of amiodarone metabolites and impurities using liquid chromatography/atmospheric pressure chemical ionization mass spectrometry 总被引:1,自引:0,他引:1
Myung SW Chang YJ Min HK Kim DH Kim M Kang TK Yoo EA Sohn YT Yim YH 《Rapid communications in mass spectrometry : RCM》2000,14(21):2046-2054
Using the high performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS) technique, together with established trends from the literature, the structures of metabolites and impurities of amiodarone, an anti-arrhythmic drug, have been assigned. By comparing analyses of products of incubation with rat liver microsomes with controls in which glucose 6-phosphate dehydrogenase was omitted, metabolites could be distinguished from impurities. Structures for the two proposed metabolites and four impurities are proposed. 相似文献
17.
A radiochemical procedure is described for the fast and sensitive measurement of uranium isotopes in gaseous and liquid effluents of nuclear facilities. Equally, this procedure is suitable to measure uranium isotopes in all kinds of environmental samples. Uranium is leached from ashed sample materials with HNO3, HF, and Al(NO3)3 solution and separated from matrix elements by extraction with trioctylphosphinic oxide and backextraction with NH4F. After radiochemical cleaning by coprecipitation with LaF3 and anion exchange, uranium isotopes are electroplated on stainless steel discs from HCl/oxalate solution. The preparation is measured by alpha-spectrometry using surface barrier detectors. The detection limit for 1000 minutes of counting time is 2 mBq per sample and nuclide, the chemical yield is in the range of 50 to 80%. 相似文献
18.
Nam-Sook Kang Seok-Joo Hong Chong-Hak Chae Sung-Eun Yoo 《Journal of Molecular Structure》2007,820(1-3):58-64
A comparative molecular field analysis (CoMFA) for phosphodiesterase (PDE) IV inhibitors has been performed to correlate their chemical structures with their observed biological activity. In this study, CoMFA model based on docking mode for active site of PDE IV can describe the relative change in magnitude of the steric and electrostatic fields as a function of the compounds. Pyridine N-oxide and pyridine group of each compound are aligned toward the metal ion in S2-sub pocket of PDE IV. The study provided a statistically valid model with good correlation and predictive power, and consequently we identified some key features that may be used to design new derivatives. 相似文献
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Jeong Hyun Kim Seung-Hyun Kang Il Nam Jung Kwan Mook Kim Bok Ryul Yoo Myong Euy Lee 《Journal of Sol-Gel Science and Technology》2004,32(1-3):31-35
Reaction of (triphenylmethyl)silanetriol (1) with cyclopentadienyltitanium trichloride (CpTiCl3) in the presence of triethylamine as a HCl scavenger gave both compounds of a partial open-cage type {[Ph3CSiO(OH)]3(Ph3CSiO3/2)(CpTiO3/2)4} (2) and cube type (Ph3CSiO3/2CpTiO3/2)4 (3). The 1:1 reaction of 1 and CpTiCl3 in toluene solvent at reflux temperature for 3 d afforded compounds 2 (22%) and 3 (36%). When 1 is reacted with a 1.5 fold excess of CpTiCl3 under the same conditions, compound 3 was obtained in high yield (81%) along with 2 in trace quantities. Compounds 2 and 3 were fully characterized by the analyses of 1H, 13C, 29Si NMR, IR, and FAB MS data. The solid-state structure of 3 was determined by a single crystal X-ray diffraction study. Compound 3 had shown to have catalytic activity for the oxidation of alkenes such as 1-octene, cyclooctene, and norbornene with t-butyl hydrogen peroxide. The effect of solvent was observed in this epoxidation reaction. The order of reactivity were decreased as follows: CHCl3 > hexane THF. 相似文献