This work describes the time-resolved fluorescence characteristics of two different photosensitizers in single cells, in detail mTHPC and 5-ALA induced PPIX, which are currently clinically used in photodynamic therapy. The fluorescence lifetime of the drugs was determined in the cells from time-gated spectra as well as single photon counting, using a picosecond pulsed diode laser for fluorescence excitation. The diode laser, which emits pulses at 398 nm with 70 ps full width at half maximum duration, was coupled to a confocal laser scanning microscope. For time-resolved spectroscopy a setup consisting of a Czerny Turner spectrometer and a MCP-gated and -intensified CCD camera was used. Time-gated spectra within the cells were acquired by placing the laser beam in "spot scan" mode. In addition, a time-correlated single photon counting module was used to determine the fluorescence lifetime from single spots and to record lifetime images. The fluorescence lifetime of mTHPC decreased from 7.5 to 5.5 ns during incubation from 1 to 6 h. This decrease was probably attributed to enhanced formation of aggregates during incubation. Fluorescence lifetime imaging showed that longer lifetimes were correlated with accumulation in the cytoplasm in the neighborhood of the cell nucleus, whereas shorter lifetimes were found in the outer cytoplasm. For cells that were incubated with 5-ALA, a fluorescence lifetime of 7.4 ns was found for PPIX; a shorter lifetime at 3.6 ns was probably attributed to photoproducts and aggregates of PPIX. In contrast from fluorescence intensity images alone, different fluorescence species could not be distinguished. However, in the lifetime image a structured fluorescence distribution in the cytoplasm was correlated with the longer lifetime and probably coincides with mitochondria. In conclusion, picosecond diode lasers coupled to a laser scanning microscope equipped with appropriate detection units allows time-resolved spectroscopy and lifetime imaging with high spatial resolution and provides numerous possibilities in cellular and pharmaceutical research.

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For surface and 3D structuring the ultra short pulsed laser systems are mostly used in combination with galvo scanners. This work reports on the synchronization of the scanner mirror motion with the clock of the laser pulses, which is usually in the range of 100 kHz and higher, by a modification of the electronic scanner control. This synchronization facilitates the placement of the small ablation craters from single pulses with the precision of about 1 µm relative to each other. The precise control of the crater positions offers the possibility to test and optimize new structuring strategies. Results of this optimization process with respect to minimum surface roughness, steepness of wall, accuracy to shape and efficiency will be presented.

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Wegen der großen Brems‐ und Anfahrkräfte sowie der Verbindung der durchgängig verschweißten Schienen mit dem Überbau spielt die Gleis‐Tragwerks‐Interaktion eine maßgebende Rolle beim Entwurf von längeren Eisenbahnbrücken. Ein wesentlicher Parameter beim Nachweis der Längskraftabtragung im Tragwerk ist die Längssteifigkeit der als Festpunkt ausgebildeten Unterbauten. Die horizontale Ersatzfedersteifigkeit, hier Unterbausteifigkeit genannt, wird i. d. R. rechnerisch über ein Pfahlrostmodell ermittelt. Im Fall der Itztalbrücke wurde die quasistatische Unterbausteifigkeit über eine Probebelastung und die „dynamische“ Unterbausteifigkeit über einen Bremsversuch experimentell ermittelt, um die Eingangsparameter für den Nachweis der Schienenspannungen und der Lager zu definieren. Zusätzlich zu den Versuchen wurden 3‐D‐Finite‐Elemente‐Analysen der Tiefgründungssysteme bestehend aus Bohrpfählen, Pfahlkopfplatten und Baugrund durchgeführt. Im Artikel wird die Versuchskonzeption, ‐durchführung und ‐auswertung für beide Versuche vorgestellt. Im Anschluss werden die Ergebnisse der Versuche mit den rechnerischen Prognosen verglichen. Diese Versuche im Realmaßstab ermöglichen wichtige Rückschlüsse auf die Qualität der rechnerischen Prognosen der Gründungsverformung zur Entwicklung eines besseren Verständnisses für das tatsächliche Verhalten des Tragwerks bei dem Längskraftabtrag.

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