Verbesserungen von Wagen

Ohne Zusammenfassung     

Synthesis of rel-(3RS,3aSR,7aSR)-3-(4-Chlorophenyl)-3a,4,5,6,7,7a-hexahydro-1-methylindolin-6-one,the Main Metabolite of the Analgesic Ro 15-8081: A Potent Amine-Uptake Inhibitor

The synthesis of the title compound 2 and its diastereoisomer 3 was accomplished using tricarbonyl[1-5-n-(4-methoxycyclohexa-2,4-dien-1-yl)]iron tetrafluoroborate ( 4 ) as a precursor to the cyclohexanone ring. The assignments of the relative configurations of 2 and 3 are based on the X-ray analysis of compound 3 . Both compounds 2 and 3 are potent inhibitors of neuronal noradrenaline uptake in rats with similar potencies in vitro as compared to amitriptyline and desipramine. Compounds 2 and 3 are less potent as serotonin-uptake inhibitors, very weak inhibitors of dopamine uptake, and virtually devoid of antinociceptive activity.     

Fullerodendrimers with peripheral triethyleneglycol chains

Triethylene glycol terminated poly(aryl ether) dendritic branches with an aldehyde function at the focal point have been prepared and attached to C₆₀ by a 1,3-dipolar cycloaddition.     

Influence of deposition conditions on the optical properties of erbium-doped yttrium oxide films grown by aerosol-UV assisted MOCVD

Erbium-doped Y₂O₃ films were prepared by aerosol-UV assisted metal-organic chemical vapour deposition (MOCVD) at 410 °C. The effects of humidity of carrier gas and UV-assistance on their structure and optical properties were investigated on the as-deposited and thermal annealed films using infrared spectroscopy, X-ray diffraction and transmission electron microscopy. It was found that the as-deposited Er:Y₂O₃ films crystallise in the Y₂O₃ cubic structure and present a very low organic contamination when the deposition takes place under high air humidity and, even better, with UV-assistance. After annealing, two different structural phases are observed corresponding to the cubic and the monoclinic structures of Y₂O₃. The Er³⁺ luminescence analysed in the visible and IR regions, shows the classical green transitions. The best optical properties were obtained with as-deposited and annealed Er:Y₂O₃ films grown under high air humidity with UV-assistance. Under such deposition conditions, ⁴I_13/2 lifetimes was found to be 3.07 and 6.1 ms for films annealed at 800 and 1000 °C, respectively, and up-conversion phenomena were underlined. This indicates that the deposition conditions, in particular air humidity, play an important role in the luminescent properties even after annealing.     

Ground state of the quasi-1D compound BaVS3 resolved by resonant magnetic x-ray scattering

Resonant magnetic x-ray scattering near the vanadium L2,3-absorption edges has been used to investigate the low temperature magnetic structure of high quality BaVS3 single crystals. Below T(N)=31 K, the strong resonance revealed a triple-incommensurate magnetic ordering at the wave vector (0.226 0.226 ξ) in hexagonal notation, with ξ=0.033. The azimuthal-angle dependence of the scattering signal and time-dependent density functional theory simulations indicate an antiferromagnetic order within the ab plane with the spins polarized along a in the monoclinic structure.     

Measuring the interactions among variables of functions over the unit hypercube

By considering a least squares approximation of a given square integrable function f:n[0,1]→R by a multilinear polynomial of a specified degree, we define an index which measures the overall interaction among variables of f. This definition extends the concept of Banzhaf interaction index introduced in cooperative game theory. Our approach is partly inspired from multilinear regression analysis, where interactions among the independent variables are taken into consideration. We show that this interaction index has appealing properties which naturally generalize several properties of the Banzhaf interaction index. In particular, we interpret this index as an expected value of the difference quotients of f or, under certain natural conditions on f, as an expected value of the derivatives of f. Finally, we discuss a few applications of the interaction index in aggregation function theory.     

Optimization of flow diverters for cerebral aneurysms

A modern technique to treat cerebral aneurysms is to insert a flow diverter in the parent artery. In order to produce an optimal design of such devices, we consider a methodology combining simulated annealing optimization and lattice Boltzmann simulations. Our results surpass, in terms of stent efficiency, those obtained in the recent literature with an other optimization method. Although our approach is still in 2D, it demonstrates the potential of the method. We give some hint on how the 3D cases can be investigated.     

Free-standing films of fluorinated surfactants as 2D matrices for organizing detergent-solubilized membrane proteins

The possibility of organizing detergent-solubilized membrane proteins in a plane within the core of Newton black films (NBFs) formed from fluorinated surfactants has been investigated. Fluorinated surfactants have the interesting characteristics of being poorly miscible with detergents and highly surface-active. As a result, when a membrane protein-the transmembrane domain of OmpA (tOmpA)-solubilized by the nonionic detergent C8E4 (tetraethylene glycol monooctyl ether) was injected under a monolayer of fluorinated surfactant, C8E4 and tOmpA/C8E4 complexes remained confined to the subphase. Vertical, macroscopic NBFs were drawn, and their structure was investigated by means of X-ray reflectivity. Depending on experimental conditions, the protein was shown to organize into either one or two monolayers stabilized by two monolayers of fluorinated surfactant. Two different mechanisms of protein insertion were investigated: (i) attachment of polyhistidine-tagged tOmpA/C8E4 complexes to nickel-bearing polar groups born by a fluorinated surfactant and (ii) spontaneous diffusion into the surfactant films. Possible applications are discussed.     

The automatic control of boundary-layer transition — Experiments and computation

In recent years there has been an increasing interest in the control of boundary-layer transition through the use of wall suction. In the current work suction is provided through one or more suction panels situated close to the leading edge of a plate. Experiments show that boundary-layer pressure fluctuation measurements can be used to identify the position of transition. Transition can be maintained at a desired location with minimum power consumption by employing an automatic adaptive feedback control loop which regulates the suction flow rates of two independent suction panels. This can be expressed as a constrained optimization problem. To allow the suction flow rates to be updated, a modified least mean squares algorithm is used within the control loop. Experimental measurements show that the control algorithm allows fast and stable convergence towards the optimum suction distribution for a double suction panel configuration. Numerical simulations have also been performed. The two-dimensional boundary layer was calculated allowing the viscous boundary layer to interact with the inviscid outer flow. Following linear stability theory the spatial growth rates are calculated by solving an Orr-Sommerfeld type eigenvalue problem, with the streamwise location of transition predicted via thee ^N -method. Applying the same optimization strategy as in the experiments, good qualitative agreement between computations and experiments was found. The optimization algorithm has been applied to computer models where the relation between suction flow rates and transition location is described by an empirical analytical function. This shows that the controller can in principle be applied to systems with more than two suction panels.Nomenclature b transition location with zero suction - d desired transition location - e(k) error signal - k iteration index - p rms pressure - p _ref reference rms pressure - r sum of the reference pressure - u streamwise velocity - u _e external velocity - inviscid external velocity - A wave amplitude - F( ) cost function - I identity matrix - N maximum amplification factor - P projection matrix - R Reynolds number - Re Reynolds number based on the boundary-layer thickness - R matrix of weights - Tu turbulence level - vector of suction flow rates - v normal velocity - v _wall suction velocity at the surface - x streamwise coordinates - x _m microphone location - x _T(k) measured transition location - y normal coordinate - y(k) sum of the measured pressures - w(k) noise - plate length - r +i _i - free stream velocity - * displacement thickness - gradient vector - Lagrange multiplier - controller gain - disturbance stream function - disturbance amplitude - wave frequency = complex wave number     

Solutions of the Time-Harmonic Wave Equation in Periodic Waveguides: Asymptotic Behaviour and Radiation Condition

In this paper, we give the expression and the asymptotic behaviour of the physical solution of a time harmonic wave equation set in a periodic waveguide. This enables us to define a radiation condition and show well-posedness of the Helmholtz equation set in a periodic waveguide.