W-bearing rutile formed during alteration of jarosite by resurgent hydrothermal fluids in the oxide zone of the Kori Kollo gold deposit. The rutile shows sector zoning in basal sections and well developed multiple growth zones, both defined in backscatter electron images by variations in the W content. The maximum WO3 content is 5.3 wt.% and W substitutes for Ti with double substitution of Fe to maintain charge balance. The causes of multiple growth bands are considered to be changes in externally controlled variables occurring in a shallow hydrothermal system. Whereas Ti is probably leached from biotite in dacitic rocks, the W is introduced by hydrothermal fluids.

We have deposited diamond films on Si〈111〉 using hot filament assisted chemical vapor deposition at low pressures ∼25 Torr. Diamond films deposited at different relative concentrations of methane (ranging from 0.25% to 2.0%) in methane-hydrogen mixtures have been characterized by Raman spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. With varying methane concentration, Raman spectra show features characteristic of crystalline diamond, diamond-like carbon, and polycrystalline graphite. Scanning electron micrographs show densely packed diamond crystallites. SEM measurements made on diamond films grown as a function of time show that the median grain size of the diamond crystallites increases linearly with time during the initial phase of the growth. X-ray photoelectron spectroscopy reveals differences between the diamond sp3 covalent bonding and sp2 graphitic bonding as well as the extent of s-p hybridization as a function of methane concentration. The plasmon loss shoulder, characteristic of graphite, is absent from the spectrum of 0.25% methane concentration film. But it appears in the XPS spectra of films grown at higher concentrations.

While the value of listing equity securities has been researched extensively, no studies have examined the market reaction to the decision to list corporate debt. Since the listing of corporate bonds on the major exchanges is a significant corporate activity, this study examines the impact of bond listing on shareholder wealth. Using a variety of possible announcement dates as well as cumulative abnormal returns between dates, no detectable market reaction to debt listing is found. Therefore, the listing of corporate bonds does not appear to be valued by the common shareholders of those same firms.