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371.
We report results of dissipative particle dynamics simulations and develop a semi-analytical theory of an anisotropic flow in a parallel-plate channel with two superhydrophobic striped walls. Our approach is valid for any local slip at the gas sectors and an arbitrary distance between the plates, ranging from a thick to a thin channel. It allows us to optimize area fractions, slip lengths, channel thickness, and texture orientation to maximize a transverse flow. Our results may be useful for extracting effective slip tensors from global measurements, such as the permeability of a channel, in experiments or simulations, and may also find applications in passive microfluidic mixing. 相似文献
372.
Kazansky VB Subbotina IR Jentoft FC Schlögl R 《The journal of physical chemistry. B》2006,110(35):17468-17477
Polarization of ethane and propane resulting from adsorption of these hydrocarbons by protons and different cations in mordenite, ZSM-5, and Y zeolites was studied by diffuse reflection Fourier transform IR spectroscopy (DRIFTS). Perturbation of adsorbed molecules by protons and sodium cations is weak, while positions of absorption bands for both these zeolites are very close to each other. In contrast, distributions of C-H IR stretching bands in intensities are somewhat different. This effect is pronounced much stronger for adsorption of light paraffins by bivalent alkaline earth and zinc cationic forms of these zeolites. Distribution of relative intensities of absorption bands strongly depends in this case both on the nature of cations and on the zeolites, while the most strongly perturbed vibrations are the initially fully symmetric C-H stretching vibrations. The corresponding low-frequency shifts and relative intensities of IR bands are increasing for different cations and zeolites in the following sequences: Na < Ca < Mg < Zn and Y < Mor approximately ZSM-5, while the difference in distribution of relative intensities of C-H stretching bands is pronounced much stronger than for the low-frequency shifts of these bands. Therefore, the relative intensities of IR C-H stretching bands are much better criterion of perturbation of light paraffins upon adsorption than the frequencies of these bands, which are traditionally used for this purpose. In addition, distribution of C-H IR stretching bands in intensity also provides unique information on anisotropy of polarizability of different C-H bonds created by their vibrations. For the acid and acid-base catalysis, where the main source of chemical activation arises from polarization of adsorbed molecules, such information is most important, while the anisotropy of polarizability provides a unique information on selective activation of different chemical bonds resulting from their stretching. The obtained results also demonstrate the possibility to use for testifying of the strength of Lewis acid sites instead of adsorption of the model molecular probes adsorption of the paraffins themselves. 相似文献
373.
Wilson OM Knecht MR Garcia-Martinez JC Crooks RM 《Journal of the American Chemical Society》2006,128(14):4510-4511
We report a particle size dependence for the rate of hydrogenation of allyl alcohol using 1.3-1.9 nm Pd dendrimer-encapsulated nanoparticle (DEN) catalysts. For particles with diameters of <1.5 nm and containing <147 Pd atoms, the modulation in catalytic activity is due to the electronic properties of the particle. For the larger particles, 1.5-1.9 nm in diameter and containing an average of 147-250 Pd atoms, the size effect is a result of geometrical constraints. Specifically, the hydrogenation reaction is shown to occur preferentially on the face atoms of the larger nanoparticles. 相似文献
374.
Ina Reiche Stefan R?hrs Joseph Salomon Birgit Kanngie?er Yvonne H?hn Wolfgang Malzer Friederike Voigt 《Analytical and bioanalytical chemistry》2009,393(3):1025-1041
The paper presents an analytical method developed for the nondestructive study of nineteenth-century Persian polychrome underglaze
painted tiles. As an example, 9 tiles from French and German museum collections were investigated. Before this work was undertaken
little was known about the materials used in pottery at that time, although the broad range of colors and shades, together
with their brilliant glazes, made these objects stand out when compared with Iranian ceramics of the preceding periods and
suggested the use of new pigments, colorants, and glaze compositions. These materials are thought to be related to provenance
and as such appropriate criteria for art-historical attribution. The analytical method is based on the combination of different
nondestructive spectroscopic techniques using microfocused beams such as proton-induced X-ray emission/proton-induced γ-ray
emission, X-ray fluorescence, 3D X-ray absorption near edge structure, and confocal Raman spectroscopy and also visible spectroscopy.
It was established to address the specific difficulties these objects and the technique of underglaze painting raise. The
exact definition of the colors observed on the tiles using the Natural Color System?? helped to attribute them to different colorants. It was possible to establish the presence of Cr- and U-based colorants as
new materials in nineteenth-century Persian tilemaking. The difference in glaze composition (Pb, Sn, Na, and K contents) as
well as the use of B and Sn were identified as a potential marker for different workshops.
Figure UV fluorescence and visible spectroscopy are two of the non-destructive analytical methods used to investigate the coloring
agents of underglaze painted tiles. Imaging of the uranium-containing areas was carried out by UV photography and identification
of the chemical species by visible spectroscopy.
相似文献
Ina ReicheEmail: |
375.
Friederike Rothe Ina Patties Rolf-Dieter Kortmann Annegret Glasow 《Molecules (Basel, Switzerland)》2022,27(11)
Multimodal treatment adding immunotherapy and photodynamic treatment (PDT) to standard therapy might improve the devastating therapeutic outcome of glioblastoma multiforme patients. As a first step, we provide investigations to optimize dendritic cell (DC) vaccination by using PDT and ionizing radiation (IR) to achieve maximal synergistic effects. In vitro experiments were conducted on murine glioblastoma GL261 cells, primary DCs differentiated from bone marrow and T cells, isolated from the spleen. Induction of cell death, reactive oxygen species, and inhibition of proliferation by tetrahydroporphyrin-tetratosylat (THPTS)-PDT and IR were confirmed by WST-1, LDH, ROS, and BrdU assay. Tumor cargo (lysate or cells) for DC load was treated with different combinations of THPTS-PDT, freeze/thaw cycles, and IR and immunogenicity analyzed by induction of T-cell activation. Cellular markers (CD11c, 83, 86, 40, 44, 69, 3, 4, 8, PD-L1) were quantified by flow cytometry. Cytotoxic T-cell response was evaluated by calcein AM assay. Immunogenicity of THPTS-PDT-treated GL261 cells lysate was superior to IR-treated lysate, or treated whole cells proven by increased DC phagocytosis, T-cell adhesion, proliferation, cytolytic activity, and cytokine release. These data strongly support the application of PDT together with IR for optimal immunogenic cell death induction in tumor cell lysate used to pulse DC vaccines. 相似文献
376.
377.
Kurt Binder Marcus Müller Friederike Schmid Andreas Werner 《Macromolecular Symposia》1999,139(1):1-11
Symmetric binary polymer mixtures are studied by Monte Carlo simulation of the bond fluctuation model, considering both interfaces between coexisting bulk phases and interfaces confined in thin films. It is found that the critical behavior of interfacial tension and width is compatible with that of the Ising model, as expected from the universality principle. In the strong segregation limit, only qualitative but not quantitative agreement with the self-consistent field (SCF) theory is found. It is argued that the SCF theory requires but for the short chains studied (N = 32 effective monomer units per chain), the limit is only reached for close to unity. Also, the effective χ-parameter decreases in the interface. It is shown that the interfacial width w does not increase by the adsorption of block copolymers as long as their areal density is still dilute (“mushroom” regime). But a broadening of interfaces does occur for thin films confined between walls at distance D, due to fluctuations that lead to for short-range forces, in agreement with experiment. 相似文献
378.
379.
380.
Stefan Albus Friederike Hammar Susanne Donner Michael Groß 《Nachrichten aus der Chemie》2001,49(2):122-127