Solid oxide fuel cell composite cathodes based on perovskite and fluorite structures

This work presents the results related to the functionally graded fluorite (F)-perovskite (P) nanocomposite cathodes for IT SOFC. Nanocrystalline fluorites (GDC, ScCeSZ) and perovskites (LSrMn, LSrFNi) were synthesized by Pechini method. Nanocomposites were prepared by the ultrasonic dispersion of F and P powders in isopropanol with addition of polyvinyl butyral. Different techniques for deposition and sintering of functionally graded cathode materials were applied including traditional approaches as well as original methods, such as radiation-thermal sintering under electron beam or microwave radiation. Morphology, microstructure and elemental composition of nanocomposites was characterized by XRD and HRTEM/SEM with EDX. Even for dense composites, the sizes of perovskite and fluorite domains remain in the nanorange providing developed P-F interfaces. Oxygen isotope heteroexchange and conductivity/weight relaxation studies demonstrated that these interfaces provide a path for fast oxygen diffusion. The redistribution of the elements between P and F phases in nanocomposites occurs without formation of insulating zirconate phases. Button-size fuel cells with nanocomposite functionally graded cathodes, thin YSZ layers and anode Ni/YSZ cermet (either bulk or supported on Ni-Al foam substrates) were manufactured. For optimized composition and functionally graded design of P-F nanocomposite cathodes, a stable performance in the intermediate temperature range with maximum power density up to 0.5 W cm⁻² at 700 °C in wet H₂/air feeds was demonstrated.     

A bit-level systolic array for digital contour smoothing

Linear operators for digital contour smoothing are described. These operators are defined by circulant Toeplitz matrices and allow to smooth digital contours in the least-squares sense. They minimize the undersampling, digitizing and quantizing error and allow to calculate invariants, such as curvature, which are not possible to calculate without smoothing. A bit-level systolic array which is capable of realizing the proposed operator is described. This array is easy to implement in VLSI, because the array cells involved are very simple. Furthermore, the array is completely pipelined on the bit-level, so that it operates with a high clock frequency achieving very high throughputs.     

Untersuchungen zur Maillard-Reaktion XX. Nachweis von Glycerinaldehyd, Dihydroxyaceton und anderen hydrophilen Zuckerabbauprodukten in Caramellisierungsgemischen

Zusammenfassung Zuckerabbauprodukte lassen sich durch Umsetzung mit O-Methylhydroxylamin und anschließende Acetylierung zu gaschromatographisch gut trennbaren Verbindungen umsetzen. In Zucker-caramellisierungsgemischen konnten so Glycerinaldehyd, Dihydroxyaceton, Erythrose, 3-Deoxyhexosulose und Methylglyoxal nachgewiesen werden. Auch in der Kruste von Brezen entstehen Glycerinaldehyd und Dihydroxyaceton.

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Investigations relating to the maillard reaction XX. Identification of glyceraldehyd dihydroxyacetone and other hydrophilic sugar degradation products in caramel mixtures

Summary Sugar degradation products can be determined by g.l.c. after reaction with O-Methylhydroxylamine and subsequent acetylation. Thus dihydroxyacetone, glyceraldehyde, erythrose, 3-deoxyhexosulose and methylglyoxale have been detected in caramelisation mixtures. Dihydroxy-acetone and glyceraldehyde could also be identified in the crust of a special bakery product.

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XIX. Mitteilung: Ledl F, Hiebl J, Severin Th (1983) 177:353–355