Transition-metal oxides and noble metals are wellknown selectivity and activity promoters in cobalt-based Fischer− Tropsch catalysis. Niobia has been shown as an effective selectivity promoter as support material; however, its low porosity limits the cobalt loading. To combine the selectivity-promoting properties of niobia with a highly porous support, niobia-modified silica was prepared and applied as a support for Co and PtCo catalysts with cobalt loadings up to 21 wt %. Niobia promotion was found to increase the C 5+ selectivity at 1 bar; however, it appeared to be ineffective at 20 bar. Promotion of Co/SiO 2 by a combination of platinum and niobia yielded an increase of the cobalt-weight normalized activity by a factor of 2−3 in the case of amorphous niobia and by a factor of 3−4 with niobia nanocrystals present, due to both an increased number of active sites and an increased cobalt-surface specific activity (turnover frequency).

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After World War II, large amounts of ammunition were dumped in surface waters worldwide, potentially releasing harmful and toxic compounds to the environment. To study their degradation, ammunition items dumped in the Eastern Scheldt in The Netherlands were surfaced. Severe damage due to corrosion and leak paths through the casings were observed, making the explosives in the ammunition accessible to sea water. Using novel techniques, the concentrations of ammunition-related compounds in the surrounding seabed and in the seawater were analyzed at 15 different locations. In the direct vicinity of ammunition, elevated concentrations of ammunition-related compounds (both metals and organic substances) were found. Concentrations of energetic compounds ranged from below the limit of detection (LoD) up to the low two-digit ng/L range in water samples, and from below the LoD up to the one-digit ng/g dry weight range in sediment samples. Concentrations of metals were found up to the low microgram/L range in water and up the low ng/g dry weight in sediment. However, even though the water and sediment samples were collected as close to the ammunition items as possible, the concentrations of these compounds were low and, as far as available, no quality standards or limits were exceeded. The presence of fouling, the low solubility of the energetic compounds, and dilution by the high local water current were concluded to be the main causes for the absence of high concentrations of ammunition-related compounds. As a conclusion, these new analytical methods should be applied to continuously monitor the Eastern Scheldt munitions dump site.

The influence of electrochemical etching on the electroluminescence properties of n-type 6H-and 4H-SiC was investigated. Luminescence was generated by forward-biasing the semiconductor in an electrolyte solution containing a hole-injecting species. The emission properties of unetched, uniformly etched, and porous-etched substrates are compared. It is shown that the spectral distribution of the luminescence and the emission intensity strongly depends on photoanodic treatment.