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21.
Capillary sodium dodecyl sulfate (SDS)-DALT electrophoresis (SDS-DALT-CE) refers to CE separation of proteins based on their size; DALT is the abbreviation for Dalton, the unit used to describe molecular weight. In this work, seven proteins from 18 to 116 kDa were denatured by SDS, labeled by 3-(2-furoyl) quinoline-2-carboxaldehyde, separated by SDS-DALT-CE in polyethylene oxide sieving matrix, and detected by laser-induced fluorescence (LIF) in a sheath flow cuvette. This method was combined with detergent differential fractionation, which is a protein fractionation method using a series of detergent-containing buffers to sequentially extract protein fractions from cells, to analyze the proteins in HT29 human colon adenocarcinoma cells. In addition, on-column labeling was demonstrated for protein analysis by SDS-DALT-CE with LIF, and applied to analysis of proteins in a single HT29 cancer cell. Most proteins had molecular masses from 10 to 120 kDa. Similar protein profiles were obtained for single cells and protein extract of a large cell population. 相似文献
22.
Multiresidue screening of pesticides in foods using retention time locking, GC-AED, database search, and GC/MS identification 总被引:1,自引:0,他引:1
Fruit and vegetable extracts were screened for over 400 pesticides by gas chromatography with atomic emission detection (GC-AED) and an experimental database. A technique called retention time locking was used to match GC-AED and GC with mass spectrometry (MS) retention times to those of the database. Samples were analyzed for sulfur, nitrogen, phosphorus, and chlorine by GC-AED. Possible pesticides were suggested by database search and identified by GC/MS. Forty-four pesticide standards were analyzed to determine the precision of retention time matching and the accuracy of the database search. Analytical retention times matched database retention times within 0.32 min. Using elemental criteria, the database search identified the correct compound for 41 of 44 pesticide standards. For blind spikes of fruit and vegetable extracts, the database suggested 22 of 26 spiked pesticides as matches. Nineteen were identified by GC/MS. The combination of retention time locking, GC-AED, database search, and GC/MS can be a powerful tool for identifying pesticides in a complex matrix. 相似文献
23.
A general synthetic route for the Pd-catalyzed cross-coupling of an arylzinc reagent with arylvinyl iodides (Negishi cross-coupling) has been developed. The system permits efficient and selective preparation of E-stilbenes and their analogues. It also functions effectively at low levels of catalyst loading without the need for an additional ligand and tolerates a wide range of functional groups including heteroaromatic substrates. A systematic study of various parameters was performed and correlated with catalyst-substrate activity. 相似文献
24.
Three acidic ent-kauranoid metabolites have been obtained as the methyl esters (7, 8, and 9) from incubation of the [17-14C]-labelled dienol (1) with Gibberella fujikuroi. Spectroscopic studies of the triol ester (7) and chemical degradation of B-ring cleaved products establish the assigned structure (7). The structures of the other two metabolite esters are indicated to be 8 and 9 from the spectroscopic data. 相似文献
25.
Energies and transition dipole moments for the lower electronic transitions in the terphenyl and quaterphenyl di-valent ions have been calculated starting from the Pople SCF MO's for the ground state ions. The configuration interaction included about one-hundred singly and doubly excited configurations. The results of the calculations for the lower allowed electronic transitions are in very satisfactory agreement with the experimental spectra. 相似文献
26.
27.
Wade D. Cook David A. Johnston 《The Journal of the Operational Research Society》1992,43(11):1055-1061
Organizations are frequently required to make long-term strategic choices regarding the design and manufacture of innovative process equipment and systems which address future needs. An important consideration in such choices is the evaluation of the unique capabilities of available suppliers. Typically, such evaluations must be made relative to multiple attributes or criteria. This paper examines one such supplier evaluation process in the context of a major international manufacturer of telecommunication equipment. The ad hoc method used by the organization to evaluate the multiple factors involved is presented, and an alternative, structured approach to deal with the multiple factors is then discussed. 相似文献
28.
Cammidge AN Nekelson F Helliwell M Heeney MJ Cook MJ 《Journal of the American Chemical Society》2005,127(47):16382-16383
A mixed condensation of a substituted and unsubstituted silicon phthalocyanine monomer, in which the former serves as a "cap" to a growing oligomeric chain, provides unprecedented access to a mixed dimer, trimers, and a tetramer. An important element of product control can be achieved by changing the ratio of the precursor monomers. 相似文献
29.
A. Shumelyuk A. Volkov S. Odoulov G. Cook D. R. Evans 《Applied physics. B, Lasers and optics》2010,100(1):101-108
Coupling of two counterpropagating coherent light waves in tin hypothiodiphosphate (Sn2P2S6, SPS) is usually strongly inhibited because of severe space charge limitations. Analysis of two-beam coupling gain is performed
for different orientations of the grating vector in this monoclinic crystal that takes into account the anisotropy of dielectric
permittivity. Gain enhancements are predicted and demonstrated experimentally for several nontraditional orientations of counterpropagating
waves. 相似文献
30.
The liquid crystalline behaviour of methyl-6-O-(n-dodecanoyl)-α-D-glucopyranoside, 1, has been characterised using X-ray diffraction and variable temperature Fourier transform infrared (FTIR spectroscopy). 1 exhibits a monotropic interdigitated smectic A phase consisting of bilayers in which the alkyl chains are overlapped. The crystal–isotropic transition is accompanied by a pronounced decrease in the strength of the hydrogen bonding network involving the sugar groups resulting in a marked change in the environment of the alkyl chains. The isotropic phase consists of disordered smectic-like domains stabilised via hydrogen bonding between the sugar groups. At the transition to the smectic A phase, a subtle change in hydrogen bonding is observed which is manifested by a change in the temperature dependence of the OH stretching peak position in the FTIR spectrum. On crystallisation, the strong hydrogen bonding network is re-established accompanied by a change in the conformational distribution of the alkyl chains. A model is proposed in which a combination of hydrogen bonding (enthalpic effects) and conformational arrangements (entropic effects) promotes initially the formation of smectic-like domains in the isotropic phase and subsequently stabilises the smectic A phase by inhibiting the microphase separation leading to the crystal phase. 相似文献