Methanol decomposition on Ni(111) and O/Ni(111).

Methanol decomposition on Ni(111) surfaces has been studied in the presence and absence of oxygen using temperature-programmed desorption and temperature-dependent sum frequency generation spectroscopy. Under both conditions the C-H and O-H bonds break, forming carbon monoxide and atomic hydrogen on the surface. No C-O bond scission was observed, limiting the number of reaction pathways. The O-H bonds break first (>150 K), forming surface methoxy, followed by C-H bond breakage (>250 K). All atomic hydrogen desorbs from the surface as H2 through H+H recombinative desorption. H2 desorbs at a higher temperature in the presence of oxygen (>300 K) than the absence of oxygen (>250 K) as the oxygen on the surface stabilizes the H atoms, forming surface hydroxide (OH). The surface oxygen also appears to stabilize the O-H and C-H bonds, leading to slightly higher dissociation temperatures. The CO molecules occupy both the bridge sites and the top sites of the Ni atoms as surface H appears to force the CO molecules to the top sites. There is a slight blueshift in the C-O bond vibration for both the O covered and O free surfaces due to CO being more mobile. On the O free surface, the C-O peak width broadens as low-frequency modes are activated. Finally, CO desorbs between 350 and 400 K.

Mycotoxin Quantification by Competitive ELISA.

Enzyme-linked immunosorbent assays (ELISAs) are useful in the quantification of antigens like mycotoxins. The zearalenone (ZEA) mycotoxin is commonly found in cereal crops such as corn and wheat, which are used in domestic and farm animal feed. When consumed by farm animals, ZEA can cause harmful reproductive effects. The procedure used to prepare corn and wheat samples for quantification is described in this chapter. An automated procedure was developed to prepare samples from known levels of ZEA in corn and wheat. The final corn and wheat samples were analyzed using a competitive ELISA specific to ZEA.