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131.
Paula R. Cable Mark Parker R. Kenneth Marcus Joseph M. Pochkowski 《Journal of the American Society for Mass Spectrometry》1995,6(2):140-147
The use of a two-dimensional charge injection device (CID) to directly image the spatial profile of impingent positively charged ions is described. By this approach, no prior conversion from an ion beam to a photon image is required. Because of the positive response of the device to plasma photons, ions that emanated from the radiofrequency glow discharge source were diverted around a photon stop and focused onto the CID. The resultant ion images were digitized via an external image processor and corrected for dark current contributions. Two-dimensional ion images and single pixel line profiles are presented. 相似文献
132.
Harishandra JadhavEsben Taarning Christian Marcus PedersenMikael Bols 《Tetrahedron letters》2012,53(8):983-985
The formation of hydroxymethylfurfural (HMF) from glucose was studied. It was found that the CrCl2-catalyzed conversion in the ionic liquid, butylmethylimidazolium chloride ([Bmim]Cl) leads to negligible quantities of 3-deoxyglucosone confirming that fructose is the main intermediate. It was found that the environmentally unfriendly chromium salt could be replaced with zeolite (H-ZSM-5) leading to a 45% yield of HMF. It was also found that the solvent [Bmim]Cl could be replaced with non-toxic tetrabutylammonium chloride (TBAC) giving a 56% yield of HMF. 相似文献
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136.
Christopher J. Wohl Marcus A. Belcher John W. Connell 《Applied Surface Science》2009,255(18):8135-8144
Topographically rich surfaces were generated by spray-coating organic solutions of a polyhedral oligomeric silsesquioxane, octakis(dimethylsilyloxy)silsesquioxane (POSS), on Kapton® HN films and exposing them to radio frequency generated oxygen plasma. Changes in both surface chemistry and topography were observed. High-resolution scanning electron microscopy indicated substantial modification of the POSS-coated polyimide surface topographies as a result of oxygen plasma exposure. Water contact angles varied from 104° for unexposed POSS-coated surfaces to ∼5° for samples exposed for 5 h. Modulation of the dispersive and polar contributions to the surface energy was determined using van Oss Good Chaudhury theory. Changes in surface energy are related to potential adhesive interactions with lunar dust simulant particles. 相似文献
137.
F. Thibault K.A. Grabow C.I. Marcus L.A. Robertson M.C. Stoffel 《Journal of Molecular Spectroscopy》2009,256(1):17-2081
Theoretical and experimental values have been determined for the pressure broadening of the ν1 + ν3 band of acetylene by hydrogen and deuterium at 195 K, and experimental values of the pressure shifts have been determined. Theoretical values have been calculated on the basis of a recent potential energy surface using the close coupling scheme. We discuss the detailed contribution of the various rotational angular momenta of the perturbing gas and the ortho and para contribution to the total pressure broadening cross-sections. We give routes to circumvent the computational cost of such calculations. Experimental values have been measured using a tunable diode laser spectrometer assuming a Voigt line shape. These pressure broadening parameters are compared with measurements performed recently at room temperature and with present measurements performed at 195 K in the ν1 + ν3 band of acetylene. A satisfactory agreement is obtained with the present results and available ones at 295 K. 相似文献
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The Monoid of Families of Quiver Representations 总被引:1,自引:0,他引:1
A monoid structure on families of representations of a quiveris introduced by taking extensions of representations in families,that is, subvarieties of the varieties of representations. Thestudy of this monoid leads to interesting interactions betweenrepresentation theory, algebraic geometry and quantum grouptheory. For example, it produces a wealth of interesting examplesof families of quiver representations, which can be analysedby representation-theoretic and geometric methods. Conversely,results from representation theory, in particular A. Schofield'swork on general properties of quiver representations, allowus to relate the monoid to certain degenerate forms of quantizedenveloping algebras. 2000 Mathematical Subject Classification: 16G20, 14L30, 17B37. 相似文献
140.
Bauser M 《Journal of chromatographic science》2002,40(5):292-296
Accurate results for the testing of combinatorial libraries necessitates high purity of the library members. Therefore, combinatorial libraries derived from a combinatorial solution or solid-phase synthesis often require the purification of compounds that do not achieve a certain purity threshold. This study describes that preparative high-performance liquid chromatography (HPLC)-mass spectrometry (MS) is the method of choice for the purification of large arrays of diverse compounds. The adoption of this technology to the workflow of a solution phase combinatorial chemistry laboratory producing more than 20,000 compounds per year is described. Furthermore, the setup and logistics are discussed as well as the purity achievable for large libraries. Efficiency, speed, quality, and universality of preparative HPLC-MS are presented in detail for a library of 140 compounds, including data logistics and downstream processes as well. 相似文献