Doping-induced broadening of the hole density-of-states in conducting polymers

The density-of-states distribution in conducting polymers reflects the energy disorder caused by electrostatic and steric interactions resulting from the different environment in which each molecule is placed. In case of p-doping (oxidation), the highest occupied molecular orbital (HOMO) manifold spreads in energy following a distribution as a result of long-range electrostatic (dipolar) interactions with the surrounding disordered host. In this paper the repercussion of the dipolar disorder on electrochemical signals of standard polypyrrole films is explored. The analysis is based on the chemical capacitance variation with the applied potential in experiments performed in quasi-equilibrium conditions. In addition to the Gaussian shape of cyclic voltammograms at low-doping levels, the model is able to qualitatively account for the current plateau usually observed at high oxidation potentials. This approach allows to estimating the dipolar moment associated to the polymer/dopant complex.     

Wet air oxidation in a catalytic membrane reactor: Model and industrial wastewaters in single tubes and multichannel contactors

Recent results on catalytic wet air oxidation applied to a membrane contactor are presented that give new insight following a series of previous publications. Model and industrial effluents are treated in both single tube and multichannel catalytic systems. Characterisation of the catalytic material (solid analyses, electron microscopy, EDS and EPMA) is carried out, in order to determine the catalyst distribution. Catalytic results show performances heavily dependent on the nature of the effluent and the operating conditions, and to a lesser extent on the catalytic membrane characteristics. At 80 °C, an industrial effluent is oxidised at a membrane surface related rate of 3.8 mmol/s/m². This result is achieved using a membrane containing about 0.1 wt.% Pt. This allows a revised and improved technico-economical evaluation of the Watercatox process.     

Aspekte der künstlichen Ernährung bei demenzkranken Patienten in der Geriatrie

Definition of the problem: The discussion of the appropriateness of artificial nutrition in patients with advanced dementia seems to be solved on medical grounds. If it is taken for granted that a solid and valid moral judgement in medical practice rests on actual medical facts, then one needs to consider normative arguments more carefully if it can be shown that the common medical understanding of the connection between advanced dementia and artificial nutrition seems misleading. This includes a critical discussion of recently published empirical studies, which are used to justify the belief that tube feeding is useless for elderly patients in terms of their nutritional state, quality of life, and mortality. Arguments and Conclusion: This paper puts forward a threefold approach: (1) the interdependence of nutritional state and type and grade of dementia is shown, (2) a working model is presented that should avoid the poor outcomes reported in the recent medical literature, and (3) it is argued that the discussion cannot be grounded solely in medical facts because of the limitations of recently published medical evidence. Normative aspects should be given more weight.     

Very low noise mixer at 115 GHz using a Mott diode cooled to 20 K

Measurements on a cooled resistive mixer are reported using a Mott-barrier diode cooled to 20 K, operating at 115 GHz and pumped with a local oscillator power as low as 150 ?W. The mixer noise temperature of 200 K is not only the lowest reported for a resistive mixer above 90 GHz but indicates that some improvement in shot-noise models for resistive mixers is desirable.     

Geschwulstbildung im Bereich der Frontz?hne bei einem Rehbock

Ohne Zusammenfassung     

Importance-driven feature enhancement in volume visualization

This paper presents importance-driven feature enhancement as a technique for the automatic generation of cut-away and ghosted views out of volumetric data. The presented focus+context approach removes or suppresses less important parts of a scene to reveal more important underlying information. However, less important parts are fully visible in those regions, where important visual information is not lost, i.e., more relevant features are not occluded. Features within the volumetric data are first classified according to a new dimension, denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature, various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance (importance compositing). The paper includes an extended discussion on several possible schemes for levels of sparseness specification. Furthermore, different approaches to importance compositing are treated.     

Multiple modes of active center communication in thiamin diphosphate-dependent enzymes

Detection of interaction between cofactors at the active centers of homodimeric and homotetrameric enzymes is usually elusive by steady-state kinetic approaches and requires protein variants where such interactions are diminished or exaggerated. In this Account, evidence for active-center interactions will be presented for the following thiamin diphosphate-dependent enzymes: yeast pyruvate decarboxylase, benzoylformate decarboxylase, and examples from the 2-oxoacid dehydrogenase multienzyme complex class. The dissymmetry of active sites is especially evident in the X-ray structures of these enzymes with substrate/substrate analogues bound. Perturbations that reveal active center communication include use of chromophoric substrates and substitutions of active center residues on putative pathways.