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941.
A general and preparatively simple access to multisubstituted indolizidines has been developed. The key step involves the fluoride ion induced intramolecular reaction of 2,3-dihydro-4-pyridones with allylsilane located in the side-chain. 相似文献
942.
The title disaccharide, 2‐{2‐{2‐[(2‐ethoxy‐3,4‐dioxocyclobut‐1‐en‐1‐yl)amino]ethoxy}ethoxy}ethyl 2‐O‐(3,6‐dideoxy‐α‐L ‐xylo‐hexopyranosyl)‐β‐d‐ galactopyranoside cyclic 4,6‐(potassium phosphate) ( 2 ), was synthesized from the two isomeric linker‐equipped galactose acceptors 9 and 10 , obtained by phosphorylation of 2‐[2‐(2‐azidoethoxy)ethoxy]ethyl 3‐O‐benzyl‐β‐d‐ galactopyranoside ( 8 ), which were glycosylated with ethyl 2,4‐di‐O‐benzyl‐3,6‐dideoxy‐1‐thio‐β‐l‐ xylo‐hexopyranoside ( 12 ; Scheme). Mainly the fully protected α‐(1 → 2)‐linked products 13 α and 14 α were formed. Catalytic hydrogenolysis/hydrogenation effected global deprotection, thereby removing the chirality at the P‐atom, and simultaneously converted the azido group in the linker to an amino group (→ 15 ). Final treatment with diethyl squarate (= 3,4‐diethoxycyclobut‐3‐ene‐1,2‐dione) gave target compound 2 , amenable for conjugation to proteins. 相似文献
943.
Iuliana Oita Hadewych Halewyck Bert Thys Bart Rombaut Yvan Vander Heyden 《Analytica chimica acta》2012
The development of capillary electrophoretic applications aiming to provide reliable stability assessment of viral suspensions, to detect subviral particles from cell extracts or to study the interactions between virus particles and various biomolecules, cannot be done without a thorough understanding of the sample matrix contribution to the observed electrophoretic behaviour. The present study thoroughly investigates the effect of the sample matrix on the electrophoretic behaviour of poliovirus injected as sample plugs of 1%, 5% and 12% effective capillary length. The effect of the sample matrix for three different poliovirus batches was evaluated. Additionally, simulated samples, obtained from concentrated poliovirus suspensions of high purity and diluted with commonly used lab buffers in order to obtain samples with either high or low conductivities, were also investigated. The goal of the study was to obtain a better understanding of the effect of the sample matrix on the signal enhancement, in order to define a general approach allowing a repeatable capillary electrophoretic (CE) separation of poliovirus from complex samples. This study clearly demonstrates that the sample matrix has an important influence on the sensitivity of the CE poliovirus separations. Translation of these observations into routine practice involves several compromises and a set of rules in order to reduce day-to-day variation and to maximize sensitivity. 相似文献
944.
945.
Tomislav Suhina Bart Weber Dr. Chantal E. Carpentier Dr. Kinga Lorincz Prof. Dr. Peter Schall Prof. Dr. Daniel Bonn Prof. Dr. Albert M. Brouwer 《Angewandte Chemie (International ed. in English)》2015,54(12):3688-3691
The area of contact between two objects was detected by using the strong enhancement of the fluorescence of rigidochromic probe molecules attached to one of the surfaces. Confinement of the molecules suppresses nonradiative decay and turns on the fluorescence. The approach is demonstrated by imaging of the contact area of a plastic sphere in contact with a flat glass surface. Our results agree excellently with the prediction of Hertz’s classical theory based on elastic deformation. 相似文献
946.
Flows on the nozzle plate of an inkjet printhead 总被引:1,自引:0,他引:1
Bart Beulen Jos de Jong Hans Reinten Marc van den Berg Herman Wijshoff Rini van Dongen 《Experiments in fluids》2007,42(2):217-224
Flow patterns of ink layers on the nozzle plate of a piezo-driven printhead are investigated. Two different flow types are
identified. First, a jet of droplets induces a radial airflow in the direction of the jet, which in turn causes a liquid flow
towards the nozzle. Second, the movement of the meniscus in the nozzle causes an equally strong flow, but completely different
flow patterns. The results are presented in a phase diagram with pulse amplitude and firing frequency as parameters. 相似文献
947.
Bart?MerciEmail author Bertrand?Naud Dirk?Roekaerts 《Flow, Turbulence and Combustion》2005,74(3):239-272
Numerical simulation results are presented for ‘Delft Flame III’, a piloted jet diffusion flame with strong turbulence–chemistry interaction. While pilot flames emerge from 12 separate holes in the experiments, the simulations are performed on a rectangular grid, under the assumption of axisymmetry. In the first part of the paper, flow and mixing field results are presented with a non-linear first order k–ε model, with the transport equation for ε based on a modeled enstrophy transport equation, for cold and reactive flows. For the latter, the turbulence model is applied in combination with pre-assumed β-PDF modeling for the turbulence–chemistry interaction. The mixture fraction serves as conserved scalar. Two chemistry models are considered: chemical equilibrium and a steady laminar flamelet model. The importance of the turbulence model is highlighted. The influence of the chemistry model is noticeable too. A procedure is described to construct appropriate inlet boundary conditions. Still, the generation of accurate inlet boundary conditions is shown to be far less important, their effect being local, close to the nozzle exit. In the second part of the paper, results are presented with the transported scalar PDF approach as turbulence–chemistry interaction model. A C1 skeletal scheme serves as chemistry model, while the EMST method is applied as micro-mixing model. For the transported PDF simulations, the model for the pilot flames, as an energy source term in the mean enthalpy transport equation, is important with respect to the accuracy of the flow field predictions. It is explained that the strong influence on the flow and mixing field is through the turbulent shear stress force in the region, close to the nozzle exit. 相似文献
948.
In (Bull Belg Math Soc Simon Stevin 4:299–316, 1997), Shult introduced a class of parapolar spaces, the so-called near-polar spaces. We introduce here the notion of a polarized non-abelian representation of a slim near-polar space, that is, a near-polar space in which every line is incident with precisely three points. For such a polarized non-abelian representation, we study the structure of the corresponding representation group, enabling us to generalize several of the results obtained in Sahoo and Sastry (J Algebraic Comb 29:195–213, 2009) for non-abelian representations of slim dense near hexagons. We show that with every polarized non-abelian representation of a slim near-polar space, there is an associated polarized projective embedding. 相似文献
949.
The research in this paper was motivated by one of the most important open problems in the theory of generalized polygons, namely the existence problem for semi–finite thick generalized polygons. We show here that no semi–finite generalized hexagon of order (2, t) can have a subhexagon H of order 2. Such a subhexagon is necessarily isomorphic to the split Cayley generalized hexagon H(2) or its point–line dual H D (2). In fact, the employed techniques allow us to prove a stronger result. We show that every near hexagon \({\mathcal{S}}\) of order (2, t) which contains a generalized hexagon H of order 2 as an isometrically embedded subgeometry must be finite. Moreover, if \({H \cong H^{D}}\)(2) then \({\mathcal{S}}\) must also be a generalized hexagon, and consequently isomorphic to either H D (2) or the dual twisted triality hexagon T(2, 8). 相似文献
950.
Stavros Argyrios Papadakis Bart Van Steirteghem 《Algebras and Representation Theory》2016,19(5):1135-1171
We determine, under a certain assumption, the Alexeev–Brion moduli scheme M of affine spherical G-varieties with a prescribed weight monoid . In Papadakis and Van Steirteghem (Ann. Inst. Fourier (Grenoble). 62(5) 1765–1809 19) we showed that if G is a connected complex reductive group of type A and is the weight monoid of a spherical G-module, then M is an affine space. Here we prove that this remains true without any restriction on the type of G. 相似文献