High-Speed X-ray Imaging

August 5, 2009

Scientists from the European Synchrotron Radiation Facility (France) the Forschungszentrum Karlsruhe, the Technische Universität Berlin and the Helmholtz Zentrum Berlin (all Germany) were able to make fast processes inside opaque objects visible, by using white synchrotron radiation to perform hard X-ray radioscopy with high spatio-temporal resolution. The required imaging detector was constructed out of a standard indirect detector in combination with a Photron SA1 CMOS-based camera. Thus, it was possible to investigate pore coalescence and individual cell wall collapse in an expanding liquid metal foam: the rupture of a film and the subsequent merger of two neighbouring bubbles could be recorded with a time sampling rate of 40000 frames per second (25 micorseconds exposure time). The results as published in the Journal of Synchrotron Radiation (http://journals.iucr.org/s/issues/2009/03/00/kv5057/ – open access) allowed to determine that the pore stability in a liquid metal foam is driven by intertia and not the viscosity of the melt. This knowledge is crucial in order to adapt metal foaming process for industrial production.

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Molecular Light Switches for Higher Resolution

Mai 29, 2009

The “Superresolution” research network, founded by the German Ministry of Education and Sciences, demonstrated a new widefield microscopy technology with resolutions better than 20 nanometers. The method is based on special dyes, which’s fluorescence can be optically and reversibly switched on and off in aqueous solutions. The dyes are bond to cellular structures by using a functional group. By switching the dyes on and off, the fluorescence emission is separated in time until only those dye molecules fluoresce that have enough distance to allow their localization as single molecules. After several thousand switching cycles, a total image is constructed (dSTORM – direct stochastic optical reconstruction microscopy). Involved in the project were the work groups of Prof. Dr. M. Sauer and Prof. Dr. J. Mattay (University of Bielefeld, Germany ), Prof. Dr. K.-H. Drexhage (University of Siegen, Germany), Prof. Dr. J. Enderlein (University of Goettingen, Germany), and Prof. Dr. S. Hell (Max Planck Institute of Biophysical Chemistry, Goettingen, Germany).

Cytoskeleton of a fixed cell. Left: Fluorescence image at standard conditions. Right: dSTORM image using molecular switches.

Cytoskeleton of a fixed cell. Left: Fluorescence image at standard conditions. Right: dSTORM image using molecular switches.