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211.
Milica Sentic Stéphane Arbault Laurent Bouffier Dragan Manojlovic Alexander Kuhn Neso Sojic 《Chemical science》2015,6(8):4433-4437
Among luminescence techniques, electrogenerated chemiluminescence (ECL) provides a unique level of manipulation of the luminescent process by controlling the electrochemical trigger. Despite its attractiveness, ECL is by essence a 2D process where light emission is strictly confined to the electrode surface. To overcome this intrinsic limitation, we added a new spatial dimension to the ECL process by generating 3D ECL at the level of millions of micro-emitters dispersed in solution. Each single object is addressed remotely by bipolar electrochemistry and they generate collectively the luminescence in the bulk. Therefore, the entire volume of the solution produces light. To illustrate the generality of this concept, we extended it to a suspension of multi-walled carbon nanotubes where each one acts as an individual ECL nano-emitter. This approach enables a change of paradigm by switching from a surface-limited process to 3D electrogenerated light emission. 相似文献
212.
213.
Silke C. Wenzel Holger Hoffmann Jidong Zhang Laurent Debussche Sabine Haag‐Richter Michael Kurz Frederico Nardi Peer Lukat Irene Kochems Heiko Tietgen Dietmar Schummer Jean‐Paul Nicolas Loreley Calvet Valerie Czepczor Patricia Vrignaud Agnes Mühlenweg Stefan Pelzer Rolf Müller Mark Brnstrup 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(51):15781-15785
214.
215.
Dr.-Ing. M. Mayr Priv.-Doz. Dr.-Ing. habil. G. Kuhn 《Archive of Applied Mechanics (Ingenieur Archiv)》1980,49(2):81-87
übersicht Mittels eines auf der Randintegralgleichungsmethode basierenden numerischen Berechnungsverfahrens werden zun?chst die Kerbfaktoren
tordierter Wellen mit kreisf?rmig ausgerundeter Einzelkerbe bestimmt und mit bekannten Ergebnissen verglichen. Dabei wird
eine von Neuber [1] angegebene Interpolations-formel gut best?tigt, die in Abh?ngigkeit von Kerbtiefe und Kerbsch?rfe eine
bequeme Bestimmung der Kerbfaktoren erlaubt. Anschlie?end wird die gegenseitige Beeinflussung von zwei in beliebigem Abstand
zueinander angeordneten kongruenten Kerben untersucht. Entsprechende Kerbfaktordiagramme werden angegeben und analytische
Interpolationsformeln für die genauere Bestimmung von Zwischenwerten aufgestellt. Ein Vergleich mit den in der Literatur bekannten
Ergebnissen von Mehrfachkerben wird vorgenommen.
Summary Stress concentration factors arising in the torsion of shafts with a circumferential notch are determined by means of a computer program, based on a boundary integral equation method, and are compared with known results. The results agree well with stress concentration factors obtained from a semiempirical interpolation formula of Neuber [1], which allows a comfortable determination of the concentration factors depending on the base radius and the depth of the grooves. In the second part the reciprocal influence of two congruent circumferential notches, located at an arbitrary distance from each other, is investigated. Corresponding stress concentration factor graphs are given and an analytical interpolation formula is drawn up. A comparison is undertaken with known results for shafts with an infinite system of small grooves.相似文献
216.
We present a pollution-free Petrov-Galerkin multiscale finite element method for the Helmholtz problem with large wave number κ. We use standard continuous Q1 finite elements at a coarse discretization scale H as trial functions. The test functions are the solutions of local problems at a finer scale h. The diameter of the support of the test functions behaves like mH for some oversampling parameter m. Provided m is of the order of log(κ) and h is sufficiently small, the resulting method is stable and quasi-optimal in the regime where H is proportional to κ−1. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
217.
218.
Jung U Kuhn S Cornelissen U Tuczek F Strunskus T Zaporojtchenko V Kubitschke J Herges R Magnussen O 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):5899-5908
Adlayers of different azobenzene-functionalized derivatives of the triazatriangulenium (TATA) platform on Au(111) surfaces were studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), gap-mode surface-enhanced Raman spectroscopy (gap-mode SERS), and cyclic voltammetry (CV). The chemical composition of the adlayers is in good agreement with the molecular structure, i.e., different chemical groups attached to the azobenzene functionality were identified. Furthermore, the presence of the azobenzene moieties in the adlayers was verified by the vibration spectra and electrochemical data. These results indicate that the molecules remain intact upon adsorption with the freestanding functional groups oriented perpendicularly to the TATA platform and thus also to the substrate surface. 相似文献
219.
220.
Kuhn SM Rubini M Müller MA Skerra A 《Journal of the American Chemical Society》2011,133(11):3708-3711
A novel kind of fluorescent protein relying on the intramolecular interplay between two different fluorophores, one of chemical origin and one of biological origin, was developed. The fluorescent non-natural amino acid l-(7-hydroxycoumarin-4-yl)ethylglycine was site-specifically incorporated into the recombinant enhanced cyan fluorescent protein (eCFP) at a permissible surface position ~20 ? away from the protein fluorophore using amber suppression in Escherichia coli with an engineered cognate Methanococcus jannaschii tRNA synthetase. The resulting eCFP(Cou) exhibited almost quantitative intramolecular Fo?rster resonance energy transfer (FRET) between its two fluorophores, showing brilliant cyan emission at 476 nm upon excitation in the near-UV at 365 nm (a wavelength easily accessible via conventional laboratory UV sources), in contrast to its natural counterpart. Thus, this fluorescent protein with unprecedented spectroscopic properties reveals an extreme apparent Stokes shift of ~110 nm between the absorption wavelength of the coumaryl group and the emission wavelength of eCFP. 相似文献