Methodological developments in overpressured-layer chromatography

Summary Since its introduction around 1977, OPLC has found widespread application and its methodology has been further developed. A possible development is gradient elution. Different continuous development methods (e.g. with eluent changeover, multistep gradient) and the possible system configurations for their execution are discussed. The advantages of the newly developed continuous development techniques are compared to earlier data. The most versatile method is demonstrated on lipid samples derived from human plasma, giving separation of six lipid classes and intra-class separation of the most polar classes in the same run.     

Investigating cellular signaling reactions in single attoliter vesicles

Understanding cellular signaling mediated by cell surface receptors is key to modern biomedical research and drug development. The discovery of a growing number of potential molecular targets and therapeutic compounds requires downscaling and accelerated functional screening. Receptor-mediated cellular responses are typically investigated on single cells or cell populations. Here, we show how to monitor cellular signaling reactions at a yet unreached miniaturization level. On the basis of our observations, cytochalasin induces mammalian cells to extrude from their plasma membrane submicrometer-sized native vesicles. They comprise functional cell surface receptors correctly exposing their extracellular ligand binding sites on the outer vesicle surface and retaining cytosolic proteins in the vesicle interior. As a prototypical example, ligand binding to the ionotropic 5-HT(3) receptor and subsequent transmembrane Ca(2+) signaling were monitored in single attoliter vesicles. Thus, native vesicles are the smallest autonomous containers capable of performing cellular signaling reactions under physiological conditions. Because a single cell delivers about 50 native vesicles, which can be isolated and addressed as individuals, our concept allows multiple functional analyses of individual cells having a limited availability and opens new vistas for miniaturized bioanalytics.     

Results from Bifurcation Analysis in Ship Dynamics

To assure safe ship operations on one hand side and to reduce operational restrictions to a minimum a proper knowledge of the ship's behavior in waves is necessary. One approach to achieve this is to generate an exact mathematical model of a ship and the fluid–structure–interaction in order to determine dangerous and safe operational conditions by analyzing the behavior with present numerical methods from nonlinear dynamics theory. Comparison between numerical simulations and experimental results as well as two sets of save and dangerous conditions for a given model of a real ship are shown. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Extreme roll motions of ships

The ship capsizing problem is one of the major challenges in naval architecture. The criterion of the International Maritime Organization (IMO) regarding capsize stability is still not including dynamic loads. Existing mathematical models of ships taking into account all degrees of freedom as well as fluid–structure–interaction can hardly be used for stability analysis with common methods from nonlinear dynamics theory due to their complexity. For the development of new better suited models a test environment has been created. A first prototype for an experimental capsize analysis is presented in this paper. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ueber die complexe Multiplication der elliptischen Functionen

Ohne Zusammenfassung     

QWalk: A quantum Monte Carlo program for electronic structure

We describe QWalk, a new computational package capable of performing quantum Monte Carlo electronic structure calculations for molecules and solids with many electrons. We describe the structure of the program and its implementation of quantum Monte Carlo methods. It is open-source, licensed under the GPL, and available at the web site http://www.qwalk.org.