Interfacial Properties and Structure Stability of Ni/Y2O3-ZrO2-TiO2 Cermet Anodes for Solid Oxide Fuel Cells

Ceramics of the ternary system Y2O3-ZrO2-TiO2 (YZT) and Ni/YZT cermets are evaluated in terms of application as anode electrodes in a Solid Oxide Fuel Cell. Wetting experiments in liquid Ni/YZT systems show that the increase of TiO2 content in the ceramic phase improves the bond strength at the metal ceramic interface, due to the reduction of the interfacial energy. Ni(40 vol%)/YZT cermets are exposed at 1000 degrees C for up to 1000 h in reducing atmosphere and exhibit an improved long term stability regarding to the electrical conductivity and the microstructure compared to the "state of the art" Ni/8YSZ (yttria(8 mol%)-stabilized zirconia) cermet. This is explained by the enhanced adherence at the Ni/ceramic interface, which suppresses the agglomeration rate of the Ni particles. The improvement of the interfacial properties diminishes the TEC values of the Ni/YZT cermets constraining the thermal expansion mismatch between the cermet anode and the 8YSZ electrolyte in the SOFCs. (C) 2005 Springer Science + Business Media, Inc

An improved HPLC method coupled to PCA for the identification of Tyrian purple in archaeological and historical samples

The efficiencies of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and pyridine to treat and solubilise Tyrian purple are compared using high performance liquid chromatography (HPLC). For the comparative study, samples of Hexaplex trunculus, collected from the area of Carthage, are treated with the three solvents and the following compounds are monitored with HPLC: indigotin, indirubin, 6'-bromoindirubin, 6-bromoindirubin, 6-bromoindigotin, 6,6'-dibromoindigotin and 6,6'-dibromoindirubin. HPLC identifications are achieved as these compounds were synthesized in pure forms and characterized using H-1 NMR, elemental analyses and IR spectroscopy. It is shown that pyridine results in poor yields compared to the quantities solubilised using DMF or DMSO. However, the relative composition of the purple dye is not affected by the solvent used for sample treatment. DMSO resulted in improved HPLC signals (peak heights) over DMF and is therefore selected for further studies. The effects of treatment temperature and time are investigated, suggesting that the best conditions correspond to 80 degrees C and 15 min.The improved method (treatment with DMSO at 80 degrees C for 15 min) is used to treat more molluscan samples which are then subjected to HPLC analysis. The results are investigated in the light of previously collected (published and unpublished) analytical data. In particular, principal component analysis (PCA) is applied, to investigate if it is possible to achieve a distinction between the three Mediterranean molluscan species (H. trunculus L., Bolinus brandaris L. and Stramonita haemastoma), using all the HPLC quantitative results reported up until now by various researchers. The PCA plot shows that B. brandaris and S. haemastoma species are not separated and H. trunculus samples are slightly separated from the other two species.The above findings are used to investigate the possible biological origin of Tyrian purple detected in historical -initially studied using X-ray fluorescence spectroscopy- and archaeological samples. Furthermore, the improved method, devised herein, resulted in the identification of monobromoindirubins in the DMSO extracts of the archaeological samples, which were not detected in previous studies where DMF was used to treat the same significant samples. (C) 2013 Elsevier B.V. All rights reserved

From Botanical Source to Analytical Result: The Influence of Recipe and Plant Source on Appearance and Composition of Anthraquinone and Flavonoid Dyes and Pigments

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