A polypyrrole-based solid-contact Pb2+-selective PVC-membrane electrode with a nanomolar detection limit

Ion-selective electrodes (ISE) based on conventional plasticized PVC membranes with solid inner contact (SC) have so far had unsatisfactory lower detection limits. Here it is shown that electropolymerization of pyrrole in the presence of potassium hexacyanoferrate(II)/(III) on Pt results in adequate inner contact for SC-ISE. The nanomolar lower detection limit achieved with the Pb2+-selective PVC membranes investigated is comparable with values obtained with optimized internal solutions of liquid-contact IS

An Urbanism oriented towards rail in Germany and France: selected findings of the Bahn.Ville project

Transit oriented development has become in the recent years a topic of high interest both for researchers and for practitioners. The French-German project Bahn.Ville 2 has the objective of testing the principles of an urbanism orientated towards rail by implementation on two regional railway lines (St. Etienne – Firminy, Lyon metropolitan region as well as Taunusbahn, Frankfurt/Rhein-Main region). This paper is presenting selected results on - innovations in regional planning instruments in France (Schéma de Cohérence Territorial) and Germany (Regionaler Flächennutzungsplan) and their respective for a better integration of land-use and transport, - specific observations on neighborhood mobility in the station surrounding and propositions for high quality walking environments as well as - the potential of an observation tool designed to support public intervention on land-use and transport around stations. The results constitute three original contributions of the Bahn.Ville 2 project in the sense of the support sustainable mobility by an urbanism orientated towards rail

Infrared study of spin crossover Fe-picolylamine complex

Infrared (IR) absorption spectroscopy has been used to probe the evolution of microscopic vibrational states upon the temperature- and photo-induced spin crossovers in [Fe(2-picolylamine)3]Cl2EtOH (Fe-pic). To overcome the small sizes and the strong IR absorption of the crystal samples used, an IR synchrotron radiation source and an IR microscope have been used. The obtained IR spectra of Fe-pic show large changes between high-spin and low-spin states for both the temperature- and the photo- induced spin crossovers. Although the spectra in the temperature- and photo-induced high-spin states are relatively similar to each other, they show distinct differences below 750 cm-1. This demonstrates that the photo-induced high-spin state involves microscopically different characters from those of the temperature-induced high-spin state. The results are discussed in terms of local pressure and structural deformations within the picolylamine ligands, and in terms of their possible relevance to the development of macroscopic photo-induced phase in Fe-pic.Comment: 6 pages (text) and 6 figures,submitted to J. Phys. Soc. Jp

Lime repellent polyethylene additives

The precipitation of calcium carbonate from hard water, commonly known as calcification or scaling, is a widespread nuisance. To avoid scaling, a physical or chemical pretreatment of water is often employed, such as ion exchange, addition of complexing agents, or the use of magnetic and electric fields. Our approach is to construct surfaces to which calcium carbonate crystals do not adhere. Here, we show that by the use of particular copolymer additives, polyethylene can be made lime repellent. The copolymers have the formula: polyethylene-block-poly(ethylene glycol) and are compounded into the polyethylene. Twelve such additives were investigated and three displayed anticalcification activity. The effective copolymers were investigated by mass spectrometry. Infrared spectroscopy of copolymer/polyethylene blends revealed that the concentration of the additive in the matrix correlates to a specific absorption band. Stability tests against hot water showed that the anticalcification activity was maintained over the timeframe investigated

Chemical Sensors and Computer-Aided Analytical Chemistry

A simplified thermodynamic model of potentiometric and optical ion sensor membranes allows to improve their properties and the measurement of complex formation constants in membrane phases. The simultaneous optical and potentiometric investigation of sensing films revealed diffusion-related long-term drifts. The lower detection limit of ion-selective electrodes was shifted from the micromolar to the picomolar range, thus allowing many new applications especially in environmental and biological trace metal analysis. Also, various prediction methods of spectroscopic and other physical data from chemical structures have been created which allow a fast compatibility check between structures and molecular spectra. Furthermore, programs are being developed for automatic spectra interpretation

The excitation of unstable perturbations in a laminar friction layer

With the aid of the method of small oscillations which was used successfully in the investigation of the stability of laminar velocity distributions in the presence of two-dimensional perturbations, the excitation of the unstable perturbations for the Hartree velocity distributions occurring in plane boundary-layer flow for decreasing and increasing pressure is calculated as a supplement to a former report. The results of this investigation are to make a contribution toward calculation of the transition point on cylindrical bodies