Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part II: analysing the chemical structure of the films

The chemical structure of cobalt--polypyrrole -- produced by a dual plasma process -- is analysed by means of X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption spectroscopy (NEXAFS), X-ray diffraction (XRD), energy-dispersive X-Ray spectroscopy (EDX) and extended x-ray absorption spectroscopy (EXAFS).It is shown that only nanoparticles of a size of 3\,nm with the low temperature crystal structure of cobalt are present within the compound. Besides that, cobalt--nitrogen and carbon--oxygen structures are observed. Furthermore, more and more cobalt--nitrogen structures are produced when increasing the magnetron power. Linking the information on the chemical structure to the results about the catalytic activity of the films -- which are presented in part I of this contribution -- it is concluded that the cobalt--nitrogen structures are the probable catalytically active sites. The cobalt--nitrogen bond length is calculated as 2.09\,\AA\ and the carbon--nitrogen bond length as 1.38\,\AA

Kohärente Lichtstreuung an photonischen Kristallen und Phasengittern

The present work deals with the diffraction of visible, coherent light from three-dimensional photonic crystals as well as three-dimensional phase lattices. The difference between the latter structures is their refractive index modulation. Although the periodic modulation of the refractive index in three dimensions is in both cases of the order of a few micrometers, the photonic phase lattices have a continuous modulation of the refractive index while the photonic crystals have a discontinuous modulation, respectively. The scattering properties of the photonic crystals / phase lattices are investigated in this thesis. The major investigation is done experimentally, but a modelling of the scattering curves is done as well. This modelling focuses on the applicability of approximate solution approaches. Therefore, a short primer on the numerical solution methods of Maxwell’s equations is given. Subsequently, approximate solutions are discussed where the attention is especially directed to the dependence and strength of the refractive index modulation. Furthermore, a short introduction of the used scattering geometry is given as well as a depiction of the experimental setup. The scattering properties of the photonic crystals, given by the so-called woodpile structure, are specifically investigated regarding their refractive index dependence. Experimentally, this is achieved via infiltration of special refractive index liquids. Moreover, a classification of scattering regimes is sought which is based on the refractive index difference. In particular a transition of the so-called kinematic scattering which can be described by the Laue equations to a more dynamic scattering regime is investigated. In order to substantiate the experimental findings, simulations based on a rigorous numerical solution of Maxwell's equations are presented. Those results confirm the experimental classification of the scattering regimes. Due to their differing refractive index modulation the holographic phase lattices are investigated in a separate part. Since the maximum refractive index difference is much smaller than the one for the previously mentioned photonic crystals and since such an investigation has been already published, a comparison of the experimental scattering efficiency of a phase lattice with a rigorous solution is omitted in favour of an approximate solution approach. This approach relies on the kinematic scattering theory. Furthermore, it is shown that this rather simple approach can well explain the light scattering from the considered structures. Merely, the scattering efficiencies cannot be described properly by the model.Die vorliegende Arbeit befasst sich mit der Diffraktion von sichtbarem, kohärentem Licht sowohl an dreidimensionalen photonischen Kristallen als auch an dreidimensionalen photonischen Raumgittern. Der Unterschied in den beiden letztgenannten Strukturen liegt in der Darstellung der Brechungsindexverteilung, die sich in beiden Fällen durch eine periodische Modulation in der Größenordnung weniger Mikrometer in drei Dimensionen auszeichnet. Während sich diese für die photonischen Kristalle unstetig verhält, vergleichbar mit einer periodischen dreidimensionalen Stufenfunktion, ändert sich die Brechungsindexverteilung für photonische Raumgitter stetig und ist etwa durch eine sinusförmige Funktion in drei Dimensionen zu beschreiben. In dieser Arbeit werden die zuvor beschriebenen photonischen Kristalle/Raumgitter auf ihre Streueigenschaften untersucht. Diese Untersuchung geschieht in erster Linie auf experimentellem Wege, allerdings wird eine Modellierung der Streukurven unter dem Gesichtspunkt der Anwendbarkeit von approximativen Lösungen ebenso diskutiert. Dazu wird zunächst skizziert welche rigorosen numerischen Methoden die Maxwellgleichungen lösen können. Im Anschluss daran werden approximative Lösungen diskutiert, die insbesondere vom Brechungsindexhub bzw. der -modulation der jeweiligen Gitter abhängen. Des Weiteren wird eine Einführung in die verwendete Streugeometrie gegeben sowie der experimentelle Arbeitsplatz erklärt. Die photonischen Kristalle der sogenannten "Woodpile-struktur" werden in dieser Arbeit auf ihre Brechungsindexabhängigkeit untersucht. Dies geschieht auf experimentellem Wege durch Infiltration spezieller Brechungsindexflüssigkeiten. Es wird zudem nach einem Übergang bzw. einer Klassifikation von verschiedenen Streuregimen gesucht. Insbesondere wird der Übergang von der sogenannten "kinematischen" Streuung, also der klassischen Lauebeugung, zu einem "dynamischeren" Streuregime untersucht. Um die experimentellen Ergebnisse zu untermauern, werden auf der rigorosen Lösung der Maxwellgleichung basierende Simulationen vorgestellt, die die experimentelle Einteilung der Regimes weitestgehend bestätigen. Wegen ihrer abweichenden Brechungsindexmodulation werden die holographischen Raumgitter separat untersucht. Da der Brechungsindexhub vergleichsweise gering ist und eine entsprechende Untersuchung bereits publiziert wurde, wird auf einen Vergleich mit einer rigorosen Lösung verzichtet. Stattdessen wird eine approximative Lösung diskutiert, die insbesondere auf der kinematischen Streutheorie beruht. Es wird weiterhin gezeigt, dass mit diesem relativ simplen Ansatz die Streuung an den gegebenen Strukturen gut beschrieben werden kann. Lediglich für die Beschreibung der Streueffizienzen ist dieses Modell nicht anwendbar

How to PROceed? Reviewing obstacles and perspectives in patient-centered digital care in radiation oncology

As the general public is increasing their online presence and is becoming confident with the digital infrastructure, an opportunity for patient-centered digital care has arisen. Electronic patient-reported outcomes, (e)PRO in short, may facilitate enhanced clinical management of radiation oncology patients. This might enable the physicians to take the initiative and counteract symptoms or undesired side effects before they aggravate and thus, reducing treatment-associated costs. In this article, we review the impetus for and modalities of (e)PRO-based data acquisition and handling in research and routine. We conclude that prospective and technical studies are needed to prove the clinical significance of (e)PROs to pave the way to monetary compensation and widespread application

Mitochondrial fusion is required for regulation of mitochondrial DNA replication.

Mitochondrial dynamics is an essential physiological process controlling mitochondrial content mixing and mobility to ensure proper function and localization of mitochondria at intracellular sites of high-energy demand. Intriguingly, for yet unknown reasons, severe impairment of mitochondrial fusion drastically affects mtDNA copy number. To decipher the link between mitochondrial dynamics and mtDNA maintenance, we studied mouse embryonic fibroblasts (MEFs) and mouse cardiomyocytes with disruption of mitochondrial fusion. Super-resolution microscopy revealed that loss of outer mitochondrial membrane (OMM) fusion, but not inner mitochondrial membrane (IMM) fusion, leads to nucleoid clustering. Remarkably, fluorescence in situ hybridization (FISH), bromouridine labeling in MEFs and assessment of mitochondrial transcription in tissue homogenates revealed that abolished OMM fusion does not affect transcription. Furthermore, the profound mtDNA depletion in mouse hearts lacking OMM fusion is not caused by defective integrity or increased mutagenesis of mtDNA, but instead we show that mitochondrial fusion is necessary to maintain the stoichiometry of the protein components of the mtDNA replisome. OMM fusion is necessary for proliferating MEFs to recover from mtDNA depletion and for the marked increase of mtDNA copy number during postnatal heart development. Our findings thus link OMM fusion to replication and distribution of mtDNA