3d metallaelectrocatalysis for resource economical syntheses

This review summarizes key developments in 3d metallaelectrocatalysis in the context of resource economy in molecular syntheses

Simulation der Schalltransmission durch Wände

Die rechnerische Vorausbestimmung der Schalldämmwirkung von Wänden bereits in der Entwurfs- und Planungsphase durch numerische Simulation gewinnt in Zeiten steigender Lärmbelastungen immer mehr an Bedeutung. Die Erfassung beliebiger geometrischer, bauphysikalischer und bauakustischer Randbedingungen sowie die Berücksichtigung der Interaktion von Fluid und Struktur spielt dabei eine entscheidende Rolle. Die numerische Simulation des Problems erfolgt mit der Finite-Element-Methode. Dabei wird das Körperschallverhalten des Bauteils im wesentlichen durch die Biegewellen bestimmt, welche mit der Mindlinschen Plattentheorie beschrieben werden. Da jedoch auch die Auswirkungen flankierender Bauteile untersucht werden, werden ebenfalls die in-plane Wellen erfaßt. Diese werden durch die dynamische, elastische Scheibengleichung dargestellt. Für die Modellierung komplexer Wandaufbauten kommt ein Homogenisierungsverfahren zum Einsatz und poröse Dämmstoffe werden mit Hilfe eines äquivalenten Fluid-Ansatzes beschrieben. Das akustische Verhalten der die Wände umgebenden Luft wird durch die Helmholtz-Gleichung erfaßt. Die Kopplung von Struktur und Fluid, also von Körper- und Luftschall, erfolgt an den Koppelflächen über die dort verrichteten virtuellen Arbeiten des Schalldruckes bzw. der Verschiebungen. Das vollständig gekoppelte Berechnungsprogramm ermöglicht z. B. neben der Ermittlung der Schalldruckverteilungen ebenso die Berechnung des Schalldämm-Maßes sowohl einschaliger als auch mehrschaliger Trennbauteile. Es werden Beispielrechnungen vorgestellt, in denen Parameterstudien sowie Vergleiche mit Messungen bzw. anderen numerischen Berechnungen durchgeführt wurden.In times of increasing noise pollution, the numerical simulation of sound transmission through solid walls, e.g., of masonry, is a challenging building acoustics topic. For an adequate building design tool it is of great importance to take arbitrary geometrical and acoustical boundary conditions as well as the air-structure interaction into account. Here, a numerical model based on the Finite Element Method is presented. The structure-borne sound is on the one hand influenced by the bending waves and on the other hand by the in-plane waves, if also the flanking transmission is investigated. The bending waves are modelled by the Mindlin plate theory and the in-plane waves by the dynamic elastic disk equation. Complicated wall constructions are treated by a homogenization technique and sound-insulating materials are described by an equivalent fluid model. The acoustic behaviour of air is characterized by the Helmholtz equation. The fluid-structure interaction is performed by using the principal of virtual work, and, as a final result, a completely coupled methodology is derived which allows the determination of sound fields and of the transmission loss of conventional solid walls. Numerical results are compared with measured values and the influence of various parameters is studied

Heterogeneous Catalytic Approaches in C-H Activation Reactions

This review summarizes the development of user-friendly, recyclable and easily separable heterogeneous catalysts for C–H activation during the last decade until December 2015

C–H arylations of 1,2,3-triazoles by reusable heterogeneous palladium catalysts in biomass-derived γ-valerolactone

C–H arylations were accomplished with a user-friendly heterogeneous palladium catalyst in the biomass-derived γ-valerolactone (GVL) as an environmentally-benign reaction medium

Heterogeneous palladium-catalysed Catellani reaction in biomass-derived γ-valerolactone

Herein, we report the unprecedented use of a heterogeneous palladium catalyst for the step-economical Catellani reaction

Hyperglycaemia but not hyperlipidaemia causes beta cell dysfunction and beta cell loss in the domestic cat

Aims/hypothesis: In vitro studies point to a toxic effect of high glucose and non-esterified fatty acids on beta cells. Whether elevated levels of glucose and lipids induce beta cell loss in vivo is less clear. The domestic cat has recently been proposed as a valuable animal model for human type 2 diabetes because feline diabetes shows several similarities with diabetes in humans, including obesity-induced insulin resistance, impaired beta cell function, decreased number of beta cells and pancreatic amyloid deposition. Methods: We infused healthy cats with glucose or lipids for 10days to clamp their blood concentrations at the approximate level found in untreated feline diabetes (glucose: 25-30mmol/l; triacylglycerols: 3-7mmol/l). Results: Glucose and lipid levels were adequately targeted. Plasma non-esterified fatty acids were increased by lipid infusion 1.7-fold. A dramatic and progressive decline of plasma insulin levels was observed in glucose-infused cats beginning after 2days of hyperglycaemic clamp. In contrast, plasma insulin concentration and glucose tolerance test were not affected by hyperlipidaemia. Compared with controls, glucose-infused cats had a 50% decrease in beta cells per pancreatic area. Apoptotic islet cells and cleaved caspase-3-positive beta cells were observed in glucose-infused cats only. Conclusions/interpretation: Sustained hyperglycaemia but not hyperlipidaemia induces early and severe beta cell dysfunction in cats, and excess glucose causes beta cell loss via apoptosis in vivo. Hyperglycaemic clamps in cats may provide a good model to study the pathogenesis of glucose toxicity in beta cell