Grain-growth mediated hydrogen sorption kinetics and compensation effect in single Pd nanoparticles

Grains constitute the building blocks of polycrystalline materials and their boundaries determine bulk physical properties like electrical conductivity, diffusivity and ductility. However, the structure and evolution of grains in nanostructured materials and the role of grain boundaries in reaction or phase transformation kinetics are poorly understood, despite likely importance in catalysis, batteries and hydrogen energy technology applications. Here we report an investigation of the kinetics of (de)hydriding phase transformations in individual Pd nanoparticles. We find dramatic evolution of single particle grain morphology upon cyclic exposure to hydrogen, which we identify as the reason for the observed rapidly slowing sorption kinetics, and as the origin of the observed kinetic compensation effect. These results shed light on the impact of grain growth on kinetic processes occurring inside nanoparticles, and provide mechanistic insight in the observed kinetic compensation effect. Grains are the building blocks of crystalline solids. Here the authors show how hydrogen-sorption induced grain-growth in Pd nanoparticles slows down the hydrogen sorption kinetics and constitutes the physical origin of corresponding kinetic compensation

Eine Bestandsaufnahme von Standardisierungspotentialen und -lücken im Cloud Computing

Die Standardisierung im Cloud Computing ist erst im Entstehen begriffen. Sie gewinnt jedoch zunehmend an Eigendynamik. Bisherige Standardisierungsbemühungen stecken konzeptionell in den Kinderschuhen, da uneinheitliche Definitionen und fehlendes Orientierungswissen ein zielorientiertes Handeln behindern. Die vorliegende Arbeit schlägt deshalb eine konsistente Taxonomie für die strukturierte Betrachtung und begriffliche Eindeutigkeit bei der Beschreibung und Bewertung von Standards vor. Darauf aufbauend wird ein Vorgehensmodell zur Analyse der aktuellen Standardisierungslage vorgestellt. Dieses verwendet eine Standardisierungslandkarte, die das Forschungsfeld anhand der Dimensionen Herausforderungen und Ansatzpunkte aufspannt. Die vorgenommene Analyse erfasst gegenwärtige Standardisierungspotentiale und -lücken im Cloud Computing. Die abschließend vorgenommene Bewertung zeigt Handlungsoptionen künftiger Standardisierungsbemühungen auf

Dynamin 2-related centronuclear myopathy: clinical, histological and genetic aspects of further patients and review of the literature

Centronuclear myopathy (CNM) is a slowly progressive congenital myopathy with characteristic histopathological findings of chains of centrally located myonuclei in a large number of muscle fibers. Recently, different missense mutations in the dynamin 2 gene (DNM2, 19p13.2) have been shown to cause autosomal dominant CNM. We re-evaluated patients with a histopathological diagnosis of CNM and report on the clinical phenotype, the biopsy findings and the genetic results of these patients and review the current literature. Two of the three patients showed an unusually late disease onset (< 40 years). Interestingly, intramuscular nerve fascicles found in the muscle biopsy of a patient harboring the E368K DNM2 mutation contained nerve fibers with disproportionately thin myelin sheaths. Schwann cells of unmyelinated nerve fibers showed abnormal plasma membrane and basal lamina protrusions, indicating peripheral nerve involvement