Synthesis Efforts of Acyclic Bis(monoalkylamino)maleonitriles and Macrocyclic Bis(dialkylamino)maleonitriles as Fluorescent Probes for Cations and a New Colorimetric Copper(II) Chemodosimeter

In this article, we report on the synthesis of acyclic bis(monoalkylamino)maleonitriles and on the intended synthesis of macrocyclic bis(dialkylamino)maleonitriles to get fluorescent probes for cations. During our efforts to synthesize macrocyclic bis(dialkylamino)maleonitriles, we were only able to isolate macrocyclic bis(dialkylamino)-fumaronitriles. The synthesis of macrocyclic bis(dialkylamino)maleonitriles is challenging, due to the fact that bis-(dialkylamino)fumaronitriles are thermodynamically more stable than the corresponding bis(dialkylamino)-maleonitriles. Further, it turned out that the acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis-(dialkylamino)fumaronitriles are no suitable tools to detect cations by a strong fluorescence enhancement. Further, only the bis(monoalkylamino)maleonitriles, which are bearing a 2-pyridyl unit as an additional complexing unit, are able to selectively recognize copper(II) by a color change from yellow to red.     

Up-scaled Dynamical Model of the Human Vocal Folds

Flow and volume flow measurements are carried out through a driven 3:1 up–scaled glottis model. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The use of an hourglass stabilized solid-shell finite element in forming simulations — theoretical aspects and first industrial applications

The method of reduced integration with hourglass stabilization is one of the most powerful techniques in the field of finite element technology. Caused by the use of a reduced number of integration points it leads to very efficient finite element formulations. To avoid the appearance of non-physical zero-energy modes an hourglass stabilization is necessary. This paper presents an adaptive hourglass stabilization strategy motivated by the hyperelastic formulation of finite inelasticity. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Numerical simulation of the filling behavior of a Non-Newtonian Fluid

A numerical model for free surface flows of non-newtonian liquids which are injected into a cavity is presented. These flows are regarded as a basic model of injection molding. Model experiments of the injection process are performed with a water-based gel. The flow equations are integrated according to the finite-volume-method. The volume of fluid method (VoF) is employed in order to describe the free surface flow of two incompressible phases, the phase interface is resolved by the method of geometric reconstruction. The Herschel-Bulkley model is used in order to describe shear-thinning behavior of the molding material and the effects of a yielding point. Different patterns of the filling flow depending on the injection parameters are evident in the experiment and the simulation. They are characterized and arranged with respect to the similarity parameters of the flow. Again, the results of the simulation are found to agree well with the experimental observations. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Application of SERS spectroscopy to the identification of (3,4-methylenedioxy)amphetamine in forensic samples utilizing matrix stabilized silver halides.

A method based on surface-enhanced Raman scattering (SERS) spectroscopy was developed to meet the need for the reliable and rapid identification of illicit drugs such as the 'designer drug' XTC, preferably to increase the security of legal certificates. A matrix stabilized silver halide dispersion on a microtiter plate is used as the SERS-active substrate, providing an easy to use system for sample preparation and probing by means of a Raman microscope. The potential of the method is demonstrated by applying it to the identification of the psychoactive ingredients of drug containing tablets which were confiscated by the local police at techno-music events. The samples of interest were 26 different brands of XTC tablets and several pieces of evidence (powders) containing amphetamine. For reference, we show SERS and Raman spectra of pristine amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethamphetamine.     

Futtermittel

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