Manuel Armin Reddemann

Time-gated ballistic imaging using a large aperture switching beam

Ballistic imaging commonly denotes the formation of line-of-sight shadowgraphs through turbid media by suppression of multiply scattered photons. The technique relies on a femtosecond laser acting as light source for the images and as switch for an optical Kerr gate that separates ballistic photons from multiply scattered ones. The achievable image resolution is one major limitation for the investigation of small objects. In this study, practical influences on the optical Kerr gate and image quality are discussed theoretically and experimentally applying a switching beam with large aperture (D = 19 mm). It is shown how switching pulse energy and synchronization of switching and imaging pulse in the Kerr cell influence the gates transmission. Image quality of ballistic imaging and standard shadowgraphy is evaluated and compared, showing that the present ballistic imaging setup is advantageous for optical densities in the range of 8 < OD < 13. Owing to the spatial transmission characteristics of the optical Kerr gate, a rectangular aperture stop is formed, which leads to different resolution limits for vertical and horizontal structures in the object. Furthermore, it is reported how to convert the ballistic imaging setup into a schlieren-type system with an optical schlieren edge.

Development steps of 2-color laser-induced fluorescence with MDR-enhanced energy transfer for instantaneous planar temperature measurement of micro-droplets and sprays

This work was performed as part of the Cluster of Excellence “Tailor-Made Fuels from Biomass”, which is funded by the Excellence Initiative of the German federal and state governments to promote science and research at German universities.

Nebulized versus Standard Local Application of Lidocaine during Flexible Bronchoscopy: A Randomized Controlled Trial

Background: Endobronchial administration of local anesthetics such as lidocaine is often used for cough suppression during bronchoscopy. To achieve a better distribution of lidocaine in the tracheobronchial tree, spray catheters have been developed, allowing nebulization of the local anesthetic solution. However, there are little data on the efficacy and safety of this approach, or on the consumption of sedative drugs and lidocaine during nebulized administration. Objectives: To investigate the tolerability of nebulized lidocaine compared to conventional lidocaine administration via syringe through the working channel of the bronchoscope in patients undergoing bronchoscopy. Consumption of sedative drugs and lidocaine was also compared between the two lidocaine administration approaches. Methods: Patients requiring bronchoscopy with endobronchial or transbronchial biopsy were randomly assigned to receive topical lidocaine either via syringe or via nebulizer. Endpoints were consumption of lidocaine and sedative drugs, as well as patient tolerance and safety. Results: Thirty patients were included, 15 in each group. Patients in the nebulizer group required lower doses of endobronchial lidocaine (184.7 ± 67.98 vs. 250.7 ± 21.65 mg, p = 0.0045) and intravenous fentanyl (0.033 ± 0.041 vs. 0.067 ± 0.045 mg, p = 0.0236) than those in the syringe group; midazolam or propofol dosages did not differ between the two groups. In addition, there were no between-group differences in patient tolerance or safety (all p > 0.05). Conclusion: Endobronchial administration of lidocaine during bronchoscopy via nebulizer was found to be well tolerated and safe and was associated with reduced lidocaine and fentanyl dosages compared to administration via syringe.

Viability of coaxial atomization for disintegration of cell solutions in cell spray applications

We gratefully acknowledge financial support from the Excellence Initiative of the German federal state governments (Exploratory Research Space, RWTH Aachen University).

Mikroskopische Analyse der Zerstäubung von Dieselstrahlen für variable Umgebungsgasdichten

Zur stetigen Optimierung motorischer Brennverfahren sind zwei grundlegende Masnahmen geeignet: eine Anpassung der motorischen Randbedingungen (wie Geometrie, Ventilstellungen, Einspritzstrategien etc.) oder eine Optimierung der Kraftstoffzusammensetzung. Kraftstoffvariationen haben hohes Potential zur Emissionsminderung, da durch Veranderung der chemischen Zusammensetzung alle fur die innermotorische Gemischbildung relevanten thermophysikalischen Stoffeigenschaften beeinflusst werden [11]. Um die Fragestellung zu ergrunden, welche Kraftstoffeigenschaften sich in welcher Weise und in welchem Ausmas auf die Verbrennung niederschlagen, ist eine globale Analyse unzureichend. Denn eine Kraftstoffanderung ausert sich in unterschiedlichen, fur das globale Verhalten relevanten und sich gegenseitig beeinflussenden Mechanismen [16].