Redox-Mediated Alcohol Oxidation Coupled to Hydrogen Gas Formation in a Dye-Sensitized Photosynthesis Cell

This work reports a dye-sensitized photoelectrochemical cell (DSPEC) that couples redox-mediated light-driven oxidative organic transformations to reductive hydrogen (H₂) formation. The DSPEC photoanode consists of a mesoporous anatase TiO₂ film on FTO (fluorine-doped tin oxide), sensitized with the thienopyrroledione-based dye AP11 , while H₂ was formed at a FTO-Pt cathode. Irradiation of the dye-sensitized photoanode transforms 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) to the oxidized TEMPO (TEMPO⁺), which acts as a chemical oxidant for the conversion of benzyl alcohol. The TEMPO^0/+ couple, previously used as redox mediator in DSSC, mediates efficient electron transfer from the organic substrate to the photo-oxidized dye. A DSPEC photoreactor was designed that allows in situ monitoring the reaction progress by infrared spectroscopy and gas chromatography. Sustained light-driven oxidation of benzyl alcohol to benzaldehyde within the DSPEC photoreactor, using of TEMPO as mediator, demonstrated the efficiency of the device, with a photocurrent of 0.4 mA cm⁻², approaching quantitative Faradaic efficiency and exhibiting excellent device stability.     

Quantitative planar Raman imaging through a spectrograph: visualisation of a supersonic wedge flow

Planar Raman imaging through a spectrograph is demonstrated as a diagnostic tool for quantitative flow visualisation of internal supersonic wedge flow. A dedicated Bayesian deconvolution filter is used to remove the spectral structure that is introduced by the spectrograph. The 2D density field is determined with ca. 10% precision using average images over 6,000 laser pulses, down to 0.5 mm from the surface of the wedge. Direct interpretations of Raman intensities provide more precise density data than indirect interpretations based on shock geometry in 2D inviscid flow.

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PVC‐Based Ion‐Selective Electrodes with Enhanced Biocompatibility by Surface Modification with “Click” Chemistry

We report here on plasticized ion‐selective poly(vinyl chloride) membranes with increased biocompatibility by means of a copper(I)‐catalyzed azide‐alkyne cycloaddition (‘click chemistry’) on the surface of finished membranes. We aimed for increasing the hydrophilicity of the surface and the application of NO releasing molecules. Employing the first principle, sodium selective membranes based on azide‐substituted PVC were modified with different length poly(ethylene glycol) (PEG) chains. For the second, cysteine groups were used as a nitrous oxide releasing substance. Surface modification was confirmed by Electrochemical Impedance Spectroscopy (EIS). Potentiometric measurements in undiluted whole blood showed an increased sensor stability in comparison to unmodified PVC. Membrane surfaces after 18 h contact with blood were analyzed with Scanning Electron Microscopy (SEM) and revealed a reduced level of blood cell adsorption on membranes modified with tetraethylene glycol (TEG) and PEGs. In contrast, cysteine modified membranes did not exhibit improved fouling resistance, suggesting that nitric oxide release by itself is not a sufficiently efficient mechanism.     

A theory of decisional power

The concept of decisional power is introduced and compared with other measures for power like those of Shapley‐Shubik, Banzhaf and Dahl. The sum of the powers of all actors in a social network is maximal for certain structures of the network. These structures are called completely democratic. Completely democratic structures are characterized. In every network dictator sets are present. These can be found by use of Boole polynomials. Decisional power turns out to‐have both a causal aspect and a utility aspect and to allow for variations that express the power over other persons as well as the power in a certain state of the network.     

Sensitivity of the DVCS Cross Section to the Compton form Factors in Scalar QED

Using deeply virtual Compton scattering as a tool to study the structure of hadrons in an exclusive process, one expresses the amplitudes in terms of invariant quantities: the Compton form factors. In this paper the sensitivity of the hadronic part of the cross section to the Compton form factors is determined.