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O. Altan Bozdemir Dr. Yusuf Cakmak Fazli Sozmen Tugba Ozdemir Aleksander Siemiarczuk Dr. Engin U. Akkaya Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(21):6346-6351
Multichromophoric boron‐dipyrromethene (Bodipy) dyes synthesized on phenylene‐ethynylene platforms have been be converted to energy transfer cassettes in a one‐step chemical transformation. Excitation energy transfer processes in these highly symmetrical derivatives were studied in detail, including time‐resolved fluorescence spectroscopy techniques. Excitation spectra and the emission lifetimes suggest efficient energy transfer between the donor and acceptor chromophore. These novel energy transfer cassettes, while highlighting a short‐cut approach to similar energy transfer systems, could be useful as large pseudo‐Stokes shift multichromophoric dyes with potential applications in diverse applications. 相似文献
125.
In this paper we have introduced a new regularity coefficient of time varying discrete linear system. On the base of this coefficient we have characterized the regularity of homogeneous discrete time varying linear systems by nonhomogeneous ones. Moreover we provided bounds for the regularity coefficient in terms of the existing in the literature regularity coefficients. 相似文献
126.
Olga Fedorova Elena Lukovskaya Artem Mizerev Yury Fedorov Alla Bobylyova Anton Maksimov Anna Moiseeva Aleksander Anisimov Gediminas Jonusauskas 《Journal of Physical Organic Chemistry》2010,23(3):246-254
A novel ditopic receptor was constructed as a combination of bisthiophene with pyridinylvinyl and crown‐containing styryl fragments. In the receptor, the pyridine residue was able to coordinate Fe2+, Cd2+, and Mg2+ metal cations, whereas the oxocrown ether moiety bound with the alkaline earth metal (Mg2+, Ca2+, and Ba2+) cations. 1H NMR, optical, electrochemical, and ESI‐MS results provided conclusive evidence of a complex formation through both the coordination centers of the molecule. The obtained results showed that cation complexation induces optical and electrochemical changes, particularly for each binding center. This type of multiparameter sensor provides interesting perspectives for the future design of unique sensors, promising different analytical techniques. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Krzysztof Ciesielski Aleksander Maliszewski 《Proceedings of the American Mathematical Society》1998,126(2):471-479
In this paper we introduce and examine a cardinal invariant closely connected to the addition of bounded functions from to . It is analogous to the invariant defined earlier for arbitrary functions by T. Natkaniec. In particular, it is proved that each bounded function can be written as the sum of two bounded almost continuous functions, and an example is given that there is a bounded function which cannot be expressed as the sum of two bounded extendable functions.
129.
Pobozy E Michalski A Sotowska-Brochocka J Trojanowicz M 《Journal of separation science》2005,28(16):2165-2172
A micellar electrokinetic chromatography method has been developed for simultaneous determination of melatonin and its precursors and metabolites. A 20 mM borate buffer pH 9.5 with 50 mM SDS served as the electrolyte. Tryptophan, 5-methoxyindoleacetic acid, 6-hydroxymelatonin, melatonin, serotonin, and 5-methoxytryptamine were baseline separated in less than 13 min. The limits of detection for UV detection and fluorometric detection based on native fluorescence of analytes were at the sub-ppm level. The proposed method with UV detection was applied to melatonin content control in pharmaceutical tablets with a precision expressed as RSD (n = 7) = 1.6%. For biological samples extraction with chloroform and ethyl acetate was examined. With ethyl acetate and chloroform recoveries of 87.2% and 82.1% melatonin, respectively, were obtained from plasma samples. The recovery of melatonin from spiked urine samples was 80.0% for ethyl acetate and 82.5% for chloroform. Fluorometric detection provides about two-fold improvement over UV in the detection of melatonin and minor improvements for three other analytes, but is much poorer than UV for tryptophan and 6-hydroxymelatonin in applied conditions. 相似文献
130.
Stare J Jezierska A Ambrozic G Kosir IJ Kidric J Koll A Mavri J Hadzi D 《Journal of the American Chemical Society》2004,126(13):4437-4443
2D free energy surfaces V = V(rOH, rO...O) for the intramolecular H-bond in the title compound were calculated by the DFT method and used in the calculation of primary and secondary chemical shifts of the compound dissolved in chloroform and acetonitrile. Solvent effects were accounted for by the SCRF/PCM method. The corresponding two-dimensional chemical shift surfaces with included solvent reaction field were obtained using the Continuous Set of Gauge Transformations approach at the B3LYP/6-311+G(2d,2p) level of theory. The chemical shifts were estimated as quantum averages along the two internal coordinates in the hydrogen bond and along several vibrational levels according to the Boltzmann distribution at room temperature. Fairly good agreement between the experimental and calculated isotope effects was obtained. 1D and 2D NMR spectra of solutions of picolinic acid N-oxide and its deuterated analogue were recorded and assigned. 相似文献