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71.
The effect of surfactants on surface instabilities of thin liquid film flow on a rotating disk was studied at different flow rates Q (0.5相似文献
72.
Efforts are described to design simple, fully flexible but conformationally preorganised omega-hydroxy-nonanoic acids that could serve as the conformation controlling unit in analogues of the potent protein-kinase C activator aplysiatoxin. Such analogues are macrodilactones incorporating the designed omega-hydroxy-nonanoic acid and 3,4-dihydroxy-pentanoic acid, which contains the pharmacophoric groups. The design process (replacement of CH(2) groups by an oxygen atom, annelation of a six-membered ring and placement of alkyl substituents) of the omega-hydroxy-nonanoic acids was monitored by force-field calculations. In the end of this process simple analogues of aplysiatoxin are proposed in which the proper disposition of the pharmacophoric groups is secured by a conformationally flexible but preorganised template structure as part of the macrodilactone ring. 相似文献
73.
74.
Scanning electron microscopy (SEM) with energy-dispersive X-ray microanalysis (EDX) is frequently used for morphological and qualitative chemical characterization of different materials. The applicability of this method for phase identification, is, however, often underestimated. The application of SEM/EDX for the characterization of different phases in fresh and altered municipal-waste incinerator bottom-ash samples with high lateral resolution is presented. Polished thin sections were prepared from the samples, but fresh fracture surfaces were also used. The EDX analyses were performed by using the correction procedures of a conventional standardless ZAF correction, a peak-to-background ZAF correction, and a correction method for light-element analysis. Because of their highly reactive properties the bottom-ash SEM samples require a special method of preparation. The method facilitates nondestructive preparation of the sensitive bottom-ash alteration phases (e.g. cement phases, hydroxides, salts) and their microstructures. 相似文献
75.
Nb4W13O47, a member of the solid solution series Nb8−nW9+nO47 (0?n?5), crystallizes in a threefold superstructure of the tetragonal tungsten bronze structure. While the oxidation of this reduced phase at TOX=1200 °C leads to a separation into the thermodynamically stable phases, lower oxidation temperatures result in products that comprise new structural elements and ordering variants. The characterization of the oxidation products obtained at TOX=1000 °C was performed by scanning transmission electron microscopy applying a high-angle annular dark field detector. At the selected imaging conditions (Z contrast), not only the metal positions are revealed by this technique but valuable additional information about the elemental distribution can be obtained simultaneously. 相似文献
76.
Ben Yahia H Gaudin E Darriet J Banks M Kremer RK Villesuzanne A Whangbo MH 《Inorganic chemistry》2005,44(9):3087-3093
A new magnetic oxide, CuMnVO4, was prepared, and its crystal structure was determined by single-crystal X-ray diffraction. The magnetic properties of CuMnVO4 were characterized by magnetic susceptibility and specific heat measurements, and the spin exchange interactions of CuMnVO4 were analyzed on the basis of spin-polarized electronic band structure calculations. CuMnVO4 contains MnO4 chains made up of edge-sharing MnO6 octahedra containing high-spin Mn2+ cations. Our work shows that CuMnVO4 undergoes a three-dimensional antiferromagnetic transition at approximately 20 K. Both the intrachain and interchain spin exchanges are antiferromagnetic, and the interchain spin exchange is not negligible compared to the intrachain spin exchange. 相似文献
77.
Time-dependent close coupling for vibrational excitation in three dimensions: Application to H+ - H2
Reinhard Schinke 《Chemical physics》1977,24(3):379-389
Impact parameter calculations for the non-reactive H+ + H2 (ni = 0) → H+ + H2 (nf) collision are reported for energies 10 eV ? Ecm ? 200 eV describing the rotational motion of the molecule in the sudden limit. The time-dependent Schrödinger equation for the vibrational motion has been solved by close coupling techniques expanding the vibrational wavefunction into both harmonic and numerically exact H2 bound states. The convergence in vibrational basis sets, where up to six vibrational levels are considered, becomes worse with decreasing energy and increasing inelasticity. Furthermore, the harmonic wavefunctions are not suitable over a large range of energies to calculate proper cross sections. The various integral and differential cross sections have been compared with the classical results of Giese and Gentry. 相似文献
78.
Erich Widmer Milan Soukup Reinhard Zell Emil Broger Hans Peter Wagner Marquard Imfeld 《Helvetica chimica acta》1990,73(4):861-867
Starting from the readily available, optically active (4R)-4-hydroxy-2,2,6-trimethylcyclohexanone ( 1 ), a new technical synthesis of (3R,3′R)-zeaxanthin is described. According to a 2(C9 + C6) + C10 = C40 construction scheme, the ketone 1 was first transformed with (E)-3-methylpent-2-en-4-yn-1-ol ( 5 ) into a C15-intermediate which, by a three-step sequence, could be converted into the known olefinic C15-Wittig salt 4 . Optimized conditions for the final Wittig reaction of 4 with the C10-dialdehyde 3 are discussed. Based on 1 , the overall yield of the entire technical process is ca. 40%. 相似文献
79.
ELISAs (enzyme-linked immunosorbent assays) are generally used in environmental analytical chemistry for screening purposes. In this work the applicability of a polyclonal-based 1-nitropyrene-ELISA for the quantification of the target analyte in air particulate matter was investigated. Validation was performed using an HPLC method with fluorescence detection of the reduced form of 1-nitropyrene. It was found that the immunoassay is not only sensitive for the target analyte but to a certain extent also for other cross-reacting molecules present in the sample, such as 2-nitropyrene and 2-nitrofluoranthene, which were identified by GC-HRMS and are considered to be products of photochemically induced reactions of pyrene or fluoranthene, respectively. The degree of correlation between ELISA and HPLC results for collected samples of air particulate matter was inversely dependent on the distance between the sampling location and the source. 相似文献
80.
The thermodynamic and extra-thermodynamic dependencies of five types of cytochrome c in water-acetonitrile mixtures of different composition in the presence of immobilised n-octyl ligands as a function of temperature from 278 K to 338 K have been investigated. The corresponding enthalpic, entropic and heat capacity parameters, deltaHdegrees assoc, deltaS degrees assoc and delta C degrees p, have been evaluated from the observed non-linear Van't Hoff plots of these globular proteins in these heterogeneous systems. The relationships between the free energy dependencies, various molecular parameters and extra-thermodynamic dependencies (empirical correlations) of these protein-non-polar ligand interactions have also been examined. Thus, the involvement of enthalpy-entropy compensation effects has been documented for the binding of these cytochrome cs to solvated n-octyl ligands. Moreover, the results confirm that this experimental approach permits changes in molecular surface area due to the unfolding of these proteins on association with non-polar ligands as a function of temperature to be correlated with other biophysical properties. This study thus provides a general procedure whereby the corresponding free energy dependencies of globular proteins on association with solvated non-polar ligands in heterogeneous two-phase systems can be quantitatively evaluated in terms of fundamental molecular parameters. 相似文献