Open Access

In recent years, much research has been done on medical laser applications inside the human body, as they are minimally invasive and therefore have fewer side effects and are less expensive than conventional therapies. In order to bring the laser light into the human body, a glass fibre with a diffuser is needed. The goal of this master thesis is the characterization and production of fibre optic diffusers that can be used for the three therapeutic applications: photodynamic therapy, laser-induced thermotherapy and endovenous laser therapy. For this purpose the following goals have to be achieved: - Optimization of the efficiency and homogeneity of internally structured diffusers - Examine damage thresholds of the diffusers in the tissue using a crash test - Achieving a better understanding of the decouple mechanism with a simulation Using an ultra-short pulse laser, modifications could be introduced into the fibre in this way that the radiation profile is homogeneous and the decoupling efficiency is 68.3 %. It was discovered that the radiation profile depends on the wavelength. Attempts have been made to improve the decoupling efficiency by mirroring the distal end of the fibre. The mirror reflects the remaining light back into the fibre, so that it is also decoupled lateral on the modifications. Vapor-deposited aluminum with physical vapor deposition is a promising approach. However, the adhesion of the coating must be improved or the coating must be protected by a mechanical cover, otherwise it will flake off too quickly. In a crash test, it was shown that the glass fibre diffusers can withstand 20 W laser power for 300 s without visible change. In an ex vivo test, the coagulation zone in the tissue was examined and it was showed that the diffusers radiate radially homogeneously. Using a ray trace simulation, the course of the light rays in the fibre was examined and the correlation of modification width and length with the decoupling efficiency was investigated. It was discovered that there are helical light rays in the fibre, which cannot be decoupled by modifications in the fibre centre.

Diese Arbeit resultiert in einem Leitfaden, der zur verbesserten Wirksamkeit von Lernmaßnahmen in Organisationen beitragen soll. Inbesondere die Verkürzung der Halbwertszeit von Wissen gab Anlass zur vorliegenden Untersuchung. In den Kapiteln zwei und drei wurde das theoretische Fundament durch Bearbeitung der Themen Personal-/Kompetenzentwicklung, allgemeine und individuelle Lerntheorie, sowie Lernbedarfsanalyse, Lerntransfer und Lernevaluation gebildet. Darauf aufbauend wurde mit der Methodik (Kapitel 4) der Experteninterviews der aktuelle Stand definierter Organisationen im Raum Ostschweiz, Westösterreich und Liechtenstein hinsichtlich Lernbedarfsanalyse, Lerntransfer und Lernevaluation erhoben. Diese Ergebnisse wurden in Kapitel 5 mit der Literaturstudie aus Kapitel 2 und 3 verglichen. Der Leitfaden besteht für Lernbedarfsanalyse, Lerntransfer und Lernevaluation aus unterschiedlichen Schritten, die in Tabellenformat dargestellt und beschrieben sind (Kapitel 6). In Kapitel 7 wurden, neben einer Zusammenfassung und einem Fazit, weiterführende Forschungsansätze zur Thematik angeführt.

Real-time measurements of the differences in inhaled and exhaled, unlabeled and fully deuterated acetone concentration levels, at rest and during exercise, have been conducted using proton transfer reaction mass spectrometry. A novel approach to continuously differentiate between the inhaled and exhaled breath acetone concentration signals is used. This leads to unprecedented fine grained data of inhaled and exhaled concentrations. The experimental results obtained are compared with those predicted using a simple three compartment model that theoretically describes the influence of inhaled concentrations on exhaled breath concentrations for volatile organic compounds with high blood:air partition coefficients, and hence is appropriate for acetone. An agreement between the predicted and observed concentrations is obtained. Our results highlight that the influence of the upper airways cannot be neglected for volatiles with high blood:air partition coefficients, i.e. highly water soluble volatiles.

Greater specific energy densities in lithium-ion batteries can be achieved by using three-dimensional (3D) porous current collectors, which allow for greater areal mass loadings of the electroactive material. In this paper, we present the use of embroidered current collectors for the preparation of thick, pouch-type Li-ion batteries. Experiments were performed on LiFePO 4 (LFP) water-based slurries using styrene-butadiene rubber (SBR) as binder and sodium carboxymethyl cellulose (CMC) as thickener, and formulations of different rheological characteristics were investigated. The electrochemical performance (cyclic voltammetry, rate capability) and morphological characteristics of the LFP half-pouch cells (X-ray micro computed tomography and scanning electron microscopy) were compared between the formulations. An optimum electrode formulation was identified, and a mechanism is proposed to explain differences between the formulations. With the optimum electrode formulation, 350 µm casted electrodes with high mechanical stability were achieved. Electrodes exhibited 4–6 times greater areal mass loadings (4–6 mAh cm −2 ) and 50% greater electroactive material weight than with foils. In tests of half- and full-pouch embroidered cells, a 50% capacity utilization at 1C-rate and 11% at 2C-rate were observed, with a full recovery at C/5-rate. The cycling stability was also maintained over 55 cycles.