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Author: Oechsner, Hans ×

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    Biomethane Potential Test: Influence of Inoculum and the Digestion System
    (Basel : MDPI, 2020) Hülsemann, Benedikt; Zhou, Lijun; Merkle, Wolfgang; Hassa, Juli; Müller, Joachim; Oechsner, Hans
    High precision of measurement of methane potential is important for the economic operation of biogas plants in the future. The biochemical methane potential (BMP) test based on the VDI 4630 protocol is the state-of-the-art method to determine the methane potential in Germany. The coefficient of variation (CV) of methane yield was >10% in several previous inter-laboratory tests. The aim of this work was to investigate the effects of inoculum and the digestion system on the measurement variability. Methane yield and methane percentage of five substrates were investigated in a Hohenheim biogas yield test (D-HBT) by using five inocula, which were used several times in inter- laboratory tests. The same substrates and inocula were also tested in other digestion systems. To control the quality of the inocula, the effect of adding trace elements (TE) and the microbial community was investigated. Adding TE had no influence for the selected, well- supplied inocula and the community composition depended on the source of the inocula. The CV of the specific methane yield was <4.8% by using different inocula in one D-HBT (D-HBT1) and <12.8% by using different digestion systems compared to D-HBT1. Incubation time between 7 and 14 days resulted in a deviation in CV of <4.8%.
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    Chemical surface and thin film analysis in glass coating
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Oechsner, Hans
    After a short overview of recent analytical techniques for compositional surface analysis and the determination of concentration depth profiles, the principle, the Instrumentation and the Performance of the routinely used electron spectroscopic and mass spectrometric methods, namely photo- and Auger electron spectroscopy as well as secondary ion and secondary neutral mass spectrometry, are described. The application of these techniques to electrically insulating surfaces and layer structures is particularly emphasized by corresponding practical examples. Secondary neutral mass spectrometry is specifically addressed with regard to the potentialities of the novel high-frequency mo d e of electron-gas secondary neutral mass spectrometry for quantitative composition analysis and high-resolution depth profiling of electrically nonconducting sample structures.