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31.
Sven Bornholdt Holger Kersten 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2013,67(8):1-11
We present a detailed study of the Gaussian laser propagation through a dielectric system composed by two right angle prisms. We investigate the transition between the spatial coherence limit, which exhibits wave-like properties and for which the resonance phenomenon can be seen, and the decoherence limit, which exhibits particle-like properties and for which the multiple diffusion occurs. We also analyze the tunneling at critical angles. In our numerical analysis, we shall use BK7 and Fused Silica prisms and a Gaussian He-Ne laser with a wavelength of 632.8 nm and beam waists of 2 mm and 200 μm. 相似文献
32.
Kersten Jörn Velasco-Sevilla Liliana 《The European Physical Journal C - Particles and Fields》2013,73(4):1-13
We present the NLO SUSY-QCD corrections to the production of a pair of the lightest neutralinos plus one jet at the LHC, appearing as a monojet signature in combination with missing energy. We fully include all non-resonant diagrams, i.e. we do not assume that production and decay factorise. We derive a parameter point based on the p19MSSM which is compatible with current experimental bounds and show distributions based on missing transverse energy and jet observables. Our results are produced with the program GoSam Cullen et al. (Eur. Phys. J. C 72:1889, 2012) for automated one-loop calculations in combination with MadDipole/MadGraph for the real radiation part. 相似文献
33.
Martin Peng Esther Mittmann Lukas Wenger Prof. Dr. Jürgen Hubbuch Dr. Martin K. M. Engqvist Prof. Dr. Christof M. Niemeyer Dr. Kersten S. Rabe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):15998-16001
Continuous flow systems for chemical synthesis are becoming a major focus in organic chemistry and there is a growing interest in the integration of biocatalysts due to their high regio- and stereoselectivity. Methods established for 3D bioprinting enable the fast and simple production of agarose-based modules for biocatalytic reactors if thermally stable enzymes are available. We report here on the characterization of four different cofactor-free phenacrylate decarboxylase enzymes suitable for the production of 4-vinylphenol and test their applicability for the encapsulation and direct 3D printing of disk-shaped agarose-based modules that can be used for compartmentalized flow microreactors. Using the most active and stable phenacrylate decarboxylase from Enterobacter spec. in a setup with four parallel reactors and a subsequent palladium(II) acetate-catalysed Heck reaction, 4-hydroxystilbene was synthesized from p-coumaric acid with a total yield of 14.7 % on a milligram scale. We believe that, due to the convenient direct immobilization of any thermostable enzyme and straightforward tuning of the reaction sequence by stacking of modules with different catalytic activities, this simple process will facilitate the establishment and use of cascade reactions and will therefore be of great advantage for many research approaches. 相似文献
34.
Two high-yielding strategies for the synthesis of 4H-anthra[1,2-b]pyran antibiotics have been developed giving access to novel antitumor agent (ED(50) 1.5 microm) and to (S)-espicufolin (3). A key step for the assembly of the tetracyclic 4H-anthra[1,2-b]pyran-4,7,12-trione skeleton is the nucleophilic addition of an aryl lithium species onto an aldehyde which allows the introduction of either an ynone or 1,3-diketo side chain, serving as precursors for an acid-catalysed cyclisation. 相似文献
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37.
Kersten M. Gericke Dr. David I. Chai Nikolas Bieler Dr. Mark Lautens Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(8):1447-1451
Shall we dance? Within the proposed mechanism for the palladium‐catalyzed title reaction, the strained alkene norbornene (or norbornadiene) enters and exits the catalytic cycle in a catalytic “square dance”, acting as both a promoter and a coupling partner in the formation of four carbon–carbon bonds, two of them by challenging C? H activation processes.
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S P Schwenzer C E Tommaseo M Kersten T Kirnbauer 《Fresenius' Journal of Analytical Chemistry》2001,371(7):927-933
Since 1886 arsenic has been known to be present as a trace component in the Wiesbaden thermal waters at concentrations of over 100 microg L(-1). In this study for the first time molecular level speciation of arsenic was measured both in the water (by HG-AAS) and in wellstone scale deposits (by XANES). Most of the arsenic in the anoxic NaCl-type waters is in the reduced arsenite form. Hydrous ferric oxide (HFO) precipitates in the scale deposits scavenge only the minor dissolved arsenate portion which is, however, accumulated up to 3% w/w. Isothermal precipitation experiments at in-situ temperatures showed a difference between the progress of both arsenic and iron oxidation and precipitation. This can be explained in terms of adsorption of the aqueous arsenite and heterogeneous oxidation on the HFO surface, but subsequently rapid release of the arsenate thereby formed back into the aqueous phase at enhanced temperature and increased pH. Such relatively rapid pseudo-homogeneous arsenite oxidation is too slow to efficiently retard the As(III) load already on the wellhead, but fast enough to prevent arsenic seepage into ground water aquifers. 相似文献
40.