Abstract.A cyclic reduction and oxidation of Ni/YSZ-cermet anodes for Solid Oxide Fuel Cells (SOFC) resulted in an increase of the polarization resistance. Therefore, investigations concerning kinetics of oxidation/reduction and the impact of redox cycles on the mi-crostructure of Ni/YSZ bulk ceramics were made. The reaction process of the basic system Ni/NiO was compared with cermet bulk samples and the influence of NiO and YSZ particle sizes and sintering temperatures on kinetics and microstructure was studied using thermo-gravimetry and dilatometry. The investigations on bulk ceramics indicated that no length change occurred during reduction, whereas reoxidation led to an increase in the length of the samples which strongly depended on the microstructure. It was shown that bulk samples sintered at temperatures below 1300 ~ can withstand redox cycles much better than those sintered at higher temperatures. Furthermore, it was found that by decreasing the NiO particle size and using a NiO/YSZ particle size ratio of aproximately 3:2, a smaller length increase after reoxidation was achieved. An increase of the polarization resistance could be ascribed to the formation of cracks within the bulk sample which interrupt current paths and therefore reduce the amount of the active triple phase boundary.

The internal reforming of methane on Ni/CGO and Ni/YSZ anodes was investigated with single cells operated at steam to carbon ratios from 0 to 3 and at temperatures of 800 °C and 950 °C. The incorporation of gas extraction ports allowed the measurement of the local gas composition in the anode gas compartment by gas chromatography. The methane conversion is presented as a function of feed gas composition, temperature, gas flow velocity, and electrical load. The impact of the anode material on the reforming reaction and on cell performance is shown. Methane conversion along the Ni/CGO anode was calculated with a one‐dimensional model; the required kinetic parameters were obtained by data fitting.

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Wood-decay white-rot and brown-rot fungi have a major economic impact on commercial and manufactured tropical and temperate woods. The aim of this study was to design a molecular method, coupled with polymerase chain reaction (PCR) and DNA sequencing, to enable early identification of various forms of fungal decay in various types of wood. The resulting tool could be used to certify the healthiness of commercial woods and also to make more efficient use of chemicals and thus reduce their negative environmental impact. Sapwood plates of Distemonanthus benthamianus,Fagus sylvatica, Lophira alata, Pinus sylvestris, and Pycnanthus angolensis were incubated in vitro in the presence of Fibroporia vaillantii, Coniophora puteana, Gloeophyllum trabeum, Pycnoporus sanguineus, and Trametes versicolor according to the EN 113 standard method. Average mass losses ranging from 2.6% to 25.0% indicated that all wood samples had been actually infected and enabled us to test the reliability of our method. PCR products were obtained in 24 of 25 combinations, and DNA sequences were obtained in 21 of the 24 fungal PCR products. DNA sequences obtained from infected wood were compared with sequences from pure strains, thus confirming the identity of the infecting strains with 100% similarity for an average of 412 bp.

bisher ungenutzte Biomasse zur Energieerzeugung oder für chemische Synthesen einzusetzen. Biomasse mit hohem Wassergehalt, wie Reststoffe aus der Landwirtschaft oder aus der Nahrungsmittelindustrie, können dabei ohne vorherige Trocknung zu einen Gasgemisch umgesetzt werden, das im Wesentlichen aus Wasserstoff und Kohlendioxid besteht. Ziel dieser Arbeit ist es, die chemischen Hauptreaktionspfade und deren Beeinflussung durch Inhaltsstoffe oder Zusätze bzw. Katalysatoren aufzuklären, um so die idealen Reaktionsbedingungen und geeignete Reaktorkonzepte für dieses Verfahren zu finden. Basierend auf Experimenten mit Modellsubstanzen und mit Modellbiomasse wurden die Hauptreaktionspfade der hydrothermalen Biomasse-Vergasung identifiziert, die in Form eines verallgemeinerten Reaktionsschemas (s. Abb.) dargestellt werden konnten. Die Reaktionspfade werden anhand charakteristischer Schlüsselsubstanzen verfolgt, die als Indikatoren für Veränderungen im Reaktionsgeschehen dienen [1]. Aus dem Vergleich der gefundenen Konzentrationen von Schlüsselsubstanzen bei Modellsubstanzen und verschiedener Biomasse kann auf den Einfluss von Inhaltsstoffen in der Biomasse geschlossen werden. So vermindern z. B. Proteine die Gasausbeute und fördern die Bildung von gelösten organischen Substanzen. Abbildung.Verallgemeinerter Reaktionsmechanismus der hydrothermalen Vergasung von Cellulose als Hauptkomponente einer Biomasse.

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