Validation of SeaWiFS-derived chlorophyll for the Rio de la Plata Estuary and adjacent waters

The South Atlantic Ocean near the Río de la Plata Estuary is a highly dynamic region that encompasses four different water bodies: the Río de la Plata, the continental shelf and the Brazil and Malvinas currents. Bio-optical measurements obtained during 6–11 November 1999 provided the initial field data for validating Sea viewing Wide Field of view Sensor (SeaWiFS)-derived chlorophyll imagery for this region. The turbid waters of the Río de la Plata Estuary showed the highest variability and complexity in water optical properties, while the offshore waters of the Brazil Current had the lowest. In most cases, the estimates of chlorophyll using the SeaWiFS algorithm were higher than in situ measured values.     

OXIDATION RATES OF CARBON BLACK PARTICLES EXPOSED TO CONCENTRATED SUNLIGHT

Small carbon particles have excellent absorption properties for concentrated solar radiation. Oxidation rates of micron and submicron sized carbon black particles have been investigated under high flux solar conditions. These oxidation rates are required for a thermal model of direct absorbing particle receivers as well as for the development of solar chemical technologies to treat toxic wastes. An experimental set-up has been developed for kinetic measurements in the solar furnace of the DLR. In the temperature range 600–900°C no significant acceleration of the oxidation could be observed due to insolation up to irradiances I≤700 kW m⁻² as compared to thermal oxidation of carbon particles (Derussol C©).     

Doping front migration in intrinsically conductive polymers and its application

Doping front migration is a recently discovered effect occurring in sandwich structures composed of intrinsically conductive polymers. A system based on chemical or electrochemical doping is capable of controlling an integrated display and modifying the electrical resistance of the conductive polymer. The effect does not require a battery and is capable of monitoring time and temperature exposure. Low-cost devices using doping front migration could be the basis of a new class of smart labels for applications such as electronic “best before” labels on food and drink.     

Asymptotic stabilization of planar systems

Sufficient conditions for the existence of a C¹ asymptotically stabilizing feedback control for planar, affine systems are given. The methods are constructive and yield homogeneous feedback controls for homogeneous systems which allow the results to be extended to more general systems.     

Coherent bidirectional communication experiment with internally bypassed star coupler in presence of Rayleigh backscattering

Internally bypassed star couplers allow bidirectional coherent communication at the same frequency via one subscriber line. For longer subscriber lines the serious limiting factor due to Rayleigh backscattering can be overcome by distributing the star.<>     

Dumbbells,Trikes and Quads: Organic–Inorganic Hybrid Nanoarchitectures Based on “Clicked” Gold Nanoparticles

The controlled assembly of gold nanoparticles in terms of the spatial arrangement and number of particles is essential for many future applications like electronic devices, sensors and labeling. Here an approach is presented to build up oligomers of mono functionalized gold nanoparticles by the use of 1,3‐bipolar azide alkyne cycloaddition click chemistry. The gold nanoparticles of 1.3 nm diameter are stabilized by one dendritic thioether ligand comprising an alkyne function. Together with di‐, tri‐ and tetra‐azide linker molecules the gold nanoparticle can be covalently coupled by a wet chemical protocol. The reaction is tracked with IR and UV–vis spectroscopy and the yielded organic‐inorganic hybrid structures are analyzed by transmission electron microscopy. To evaluate the success of this click chemistry reaction statistical analysis of the formed oligomers is performed. The geometric and spatial arrangements of the found oligomers match perfectly the calculated values for the used linker molecules. Dimers, trimers and tetramers could be identified after the reaction with the corresponding linker molecule. The results of this model reaction suggest that the used click chemistry protocol is working well with mono functionalized gold nanoparticles.