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41.
42.
Donald C. Berndt Jill E. Angus Michael J. Wood Richard F. Atkinson Tanveer A. Qureshi Brian J. Shay Aura I. Provancher 《国际化学动力学杂志》1989,21(6):431-437
Rates of reaction for the alkaline hydrolysis of various hydroxamic acids in the presence of cetyltrimethylammonium bromide have been determined. Empirical reaction orders of zero, one-half, and one were found for the hydroxamic acids depending upon reaction conditions and substrate structure. N -methylhydroxamic acids exhibited only first-order kinetics. The results are consistent with the Michaelis-Menten rate equation. 相似文献
43.
Solntsev KM Sullivan EN Tolbert LM Ashkenazi S Leiderman P Huppert D 《Journal of the American Chemical Society》2004,126(39):12701-12708
Time-resolved and steady-state emission characterization of 10-hydroxycamptothecin reveals a rich but less complex proton-transfer behavior than its parent hydroxyquinoline. The electronic effect of the additional electron-withdrawing ring makes the excited-state both less basic and more acidic than the parent and adds to the class of high-acidity excited-state proton donors in photochemistry and photobiology. 相似文献
44.
We demonstrate the existence of a new steady-state magnetic reconnection configuration which lies at the boundary of the basins of attraction between the Sweet-Parker and Hall reconnection configurations. The solution is linearly unstable to small perturbations and its identification required a novel iterative numerical technique. The eigenmodes of the unstable solution are localized near the X line, suggesting that the onset of fast reconnection in a weakly collisional plasma is initiated locally at the X line as opposed to remotely at the boundaries. 相似文献
45.
Salman H Tal S Chuvilov Y Solovey O Abraham Y Kapon M Suwinska K Eichen Y 《Inorganic chemistry》2006,45(14):5315-5320
3-(3-Ethoxymethyl-1H-imidazol-2-yl)-3-(1-ethoxymethyl-1H-imidazol-2-yl)-3H-benzo[de]isochromen-1-one, 4, is a novel photoinduced electron transfer (PET) chemosensor that becomes fluorescent upon binding metal ions and shows a strong preference toward Zn(II) ions. The new bisimidazol PET sensor and its zinc complex were prepared and characterized in terms of their crystal structures, absorption and emission spectra, and orbital energy diagrams. Free 4 is a weakly luminescent species. On the basis of detailed DFT calculations, we suggest that the poor luminescence yield of free 4 originates from its orbital structure in which two pi-orbitals of the two imidazole rings, HOMO and HOMO-1, are situated between two pi-orbitals of the isochromene-one system, HOMO-2 and LUMO. The absorption and emission processes occur between the two pi-orbitals of the isochromene-one system, HOMO-2 and LUMO, and the two pi-imidazole orbitals serve as quenchers for the excited state of the molecule through nonradiative processes. Upon binding Zn(II) ions, 4 becomes a highly luminescent species having a luminescence maximum peaking at 375 nm (lambda(ex) = 329 nm). The significant 900-fold enhancement in luminescence upon binding of the Zn(II) ions is attributed to the stabilization of the pi-orbitals of the imidazole rings upon their engagement in new bonds with the zinc ion. The affinity of 4 to zinc ions in acetonitrile is found to be very high, Ka > 3 x 10(6) M(-1), while with other metals ions, the association constants are considerably weaker. 相似文献
46.
The propagation of reconnection signatures and their associated energy are examined using kinetic particle-in-cell simulations and Cluster satellite observations. It is found that the quadrupolar out-of-plane magnetic field near the separatrices is associated with a kinetic Alfvén wave. For magnetotail parameters, the parallel propagation of this wave is super-Alfvénic (V(∥) ~ 1500-5500 km/s) and generates substantial Poynting flux (S ~ 10(-5)-10(-4) W/m(2)) consistent with Cluster observations of magnetic reconnection. This Poynting flux substantially exceeds that due to frozen-in ion bulk outflows and is sufficient to generate white light aurora in Earth's ionosphere. 相似文献
47.
Observations of an extremely elongated electron diffusion region occurring during fast reconnection are presented. Cluster spacecraft in situ observations of an expanding reconnection exhaust reveal a broad current layer ( approximately 10 ion skin depths thick) supporting the reversal of the reconnecting magnetic field together with an intense current embedded at the center that is due to a super-Alfvénic electron outflow jet with transverse scale of approximately 9 electron skin depths. The electron jet extends at least 60 ion skin depths downstream from the X-line. 相似文献
48.
We have used the turbulent flow of hot air to improve the diffraction limits of resolution in an imaging system. A time-multiplexing approach was applied and used the turbulent flow near the object to encode its spatially high frequencies. The turbulent perturbations were extracted and numerically implemented to decode the high-resolution image. Experimental verification demonstrated the proposed concept. 相似文献
49.
50.
Shay Mailloux Nataliia Guz Maria Gamella Carballo José M. Pingarrón Evgeny Katz 《Analytical and bioanalytical chemistry》2014,406(20):4825-4829
A new sense-and-act system was realized by integrating a biocatalytic/bioaffinity electrode responding to immune signals represented by an antibody and a polymer-modified electrode loaded with drug-mimicking species. The release of the drug-mimicking species was achieved specifically in response to a signal antibody, thus demonstrating for the first time an immune-induced drug-releasing process. The present approach promises new options for future applications in controlled drug release and personalized medicine. Figure
Electrochemical immune-sensing system was integrated with the substance-releasing modified electrode to demonstrate the immune-triggered drug release process 相似文献