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521.
522.
Bram Verbelen Lucas Cunha Dias Rezende Stijn Boodts Jeroen Jacobs Prof. Luc Van Meervelt Prof. Johan Hofkens Prof. Wim Dehaen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12667-12675
A one‐step synthetic procedure for the radical C?H alkylation of BODIPY dyes has been developed. This new reaction generates alkyl radicals through the oxidation of boronic acids or potassium trifluoroborates and allows the synthesis of mono‐, di‐, tri‐, and tetraalkylated fluorophores in a good to excellent yield for a broad range of organoboron compounds. Using this protocol, multiple bulky alkyl groups can be introduced onto the BODIPY core thus creating solid‐state emissive BODIPY dyes. 相似文献
523.
Conformational Analysis,Thermal Rearrangement,and EI‐MS Fragmentation Mechanism of (1(10)E,4E,6S,7R)‐Germacradien‐6‐ol by 13C‐Labeling Experiments
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Patrick Rabe Lena Barra Jan Rinkel Dr. Ramona Riclea Dr. Christian A. Citron Tim A. Klapschinski Aron Janusko Prof. Dr. Jeroen S. Dickschat 《Angewandte Chemie (International ed. in English)》2015,54(45):13448-13451
An uncharacterized terpene cyclase from Streptomyces pratensis was identified as (+)‐(1(10)E,4E,6S,7R)‐germacradien‐6‐ol synthase. The enzyme product exists as two interconvertible conformers, resulting in complex NMR spectra. For the complete assignment of NMR data, all fifteen (13C1)FPP isotopomers (FPP=farnesyl diphosphate) and (13C15)FPP were synthesized and enzymatically converted. The products were analyzed using various NMR techniques, including 13C, 13C COSY experiments. The (13C)FPP isotopomers were also used to investigate the thermal rearrangement and EI fragmentation of the enzyme product. 相似文献
524.
We consider classes of cooperative games. We show that we can efficiently compute an allocation in the intersection of the
prekernel and the least core of the game if we can efficiently compute the minimum excess for any given allocation. In the
case where the prekernel of the game contains exactly one core vector, our algorithm computes the nucleolus of the game. This
generalizes both a recent result by Kuipers on the computation of the nucleolus for convex games and a classical result by
Megiddo on the nucleolus of standard tree games to classes of more general minimum cost spanning tree games. Our algorithm
is based on the ellipsoid method and Maschler's scheme for approximating the prekernel.
Received February 2000/Final version April 2001 相似文献
525.
Assessment of Uncertainties in Modeling of Laminar to Turbulent Transition for Transonic Flows 总被引:1,自引:0,他引:1
Rene Pecnik Jeroen A. S. Witteveen Gianluca Iaccarino 《Flow, Turbulence and Combustion》2013,91(1):41-61
The effect of physical variability and uncertainty in model correlations on laminar-turbulent transition in transonic flows is computed using two different Stochastic Collocation methods. Physical variability in the boundary conditions is first investigated for a flow over a flat plate with and without pressure gradient to quantify the uncertainties on the skin friction distribution along the plate surface. Since the laboratory conditions for the flat plate test cases are well defined and the applied transition model has been tuned for these cases, good agreement with experiments is achieved and the variability in the output is low. The second investigated cases exhibit boundary layer transition on the surface of a highly loaded turbine guide vane under transonic flow conditions. Comparisons between the predicted and measured wall heat transfer are used to quantify uncertainties in the free stream turbulence and the model correlations that accounts for compressibility effects on the onset and extension of the bypass transition. The computational results show that the uncertainties have a significant impact on the transition location for the turbine guide vane simulations and, consequently, on the reliability of the predictions for compressible flows. The output uncertainty accounts to a large extent for the difference between the deterministic simulation and the experiments. The results from the Simplex Stochastic Collocation method are computationally more efficient than those of the Stochastic Collocation based on Clenshaw–Curtis quadrature. 相似文献
526.
Francesca E. Watson Simon A. Mathias Jeroen van Hunen Susie E. Daniels Richard R. Jones 《Transport in Porous Media》2012,94(3):729-745
Leakage of CO2 through fractures in saline formations will increase the CO2??brine interface and promote CO2 dissolution. We use a 2D, finite difference MATLAB model to simulate dissolution rates from a vertical fracture, with CO2 flowing through it, in a secondary storage formation. The instigation of convection currents increases dissolution rates leading to higher dissolution in higher Rayleigh number systems. Comparison of our results with fracture flow rates shows that for typical fracture apertures dissolution from a fracture is small relative to the amount of CO2 flowing through the fracture. Temporal and spatial variations in fracture permeability may reduce fracture flow rates and increase the relative amount of CO2 dissolved from the fracture compared to the CO2 flowing through the fracture. Further work on CO2 dissolution in relation to fracture heterogeneity, flow of CO2 within fractures and the interaction of multiple fractures will improve our ability to predict CO2 dissolution rates for site characterisation. 相似文献
527.
528.
Albertus P. H. J. Schenning Michel Fransen Jeroen K. J. van Duren Paul A. van Hal Ren A. J. Janssen E. W. Meijer 《Macromolecular rapid communications》2002,23(4):271-275
Polymerization of a functionalized acetylene was successfully performed using a Rh complex as the catalyst and triethylamine as a base yielding poly{(E,E,E)‐4‐[4‐[4‐(3,4,5‐tridodecyloxystyryl)‐2,5‐bis((S)‐2‐methylbutoxy)styryl]‐2,5‐bis((S)‐2‐methylbutoxy)styryl]phenylacetylene} ( PAOPV ). Films of PAOPV mixed with a fullerene derivative showed electron transfer from the OPV oligomer donor to the fullerene acceptor. The films could be furthermore used in photovoltaic devices. 相似文献
529.
Herman F.M. Schoo Rob C.J.E. Demandt Jeroen J.M. Vleggaar Coen T.H. Liedenbaum 《Macromolecular Symposia》1998,125(1):165-170
The syntheses of partially conjugated alkoxy substituted Poly(p-phenylenevinylene) (PPV) materials with tertiary amines and cationic species covalently bound to the polymer backbone are described. The amine/cationic species are introduced via a polymer analogous reaction of a functional alcohol and the chloro-precursor polymer. Single layer, polymer light emitting diodes (PolyLEDs), prepared with the modified polymer materials show a strong ‘burn-in’ effect, leading to very high electroluminescence (EL) quantum efficiencies especially with higher workfunction cathodes. 相似文献
530.
Jeroen Bomon Elias Van Den Broeck Mathias Bal Dr. Yuhe Liao Dr. Sergey Sergeyev Prof. Dr. Veronique Van Speybroeck Prof. Dr. Bert F. Sels Prof. Dr. Bert U. W. Maes 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3087-3092
An efficient conversion of biorenewable ferulic acid into bio-catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C−O (demethylation) and C−C (de-2-carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H2SO4) as catalyst in pressurized hot water (250 °C, 50 bar N2). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di- (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work-up. 相似文献