Molybdenum disulfide in the poorly crystalline "rag" structure.

Molybdenum disulfide has been prepared in an unusual poorly crystalline form, termed the "rag" structure, consisting of several stacked but highly folded and disordered S-Mo-S layers. This previously unknown structure demonstrates the flexible and macromolecular nature of the layered transition metal dichalcogenides. The determination of this structure provides a basis for understanding its highly broadened x-ray diffraction pattern and relatively low surface area, and is a starting point for optimizing the catalytic and surface properties of molybdenum disulfide.

Edge surfaces in lithographically textured molybdenum disulfide.

Lithographic techniques were used to expose edge surfaces in layered molybdenum disulfide single crystals. This microstructuring produced ideal samples for the study of the surface morphology and electronic structure of this catalytically important material. The optical absorption that was measured at mid-gap increased by two orders of magnitude after texturing. This increase resulted from reduced molybdenum at surface defects that are located on edge planes, as shown by photoemission spectroscopy. This information cannot easily be obtained on conventional crystals with predominantly basal plane surfaces.

Fibrous apatite grown on modified collagen.

Fibrous apatite has been grown by the enzymatic hydrolysis of calcium beta-glycerophosphate on reconstituted calfskin collagen tapes which had been modified by the addition of a phosphoprotein, phosvitin, in the presence of a cross-linking agent, dimethylsuberimidate. The deposits were identified as a carbonate-bearing hydroxyapatite by x-ray diffraction, and scanning electron micrographs confirmed their fibrous character.

Characterization of Cr(VI) binding and reduction to Cr(III) by the agricultural byproducts of Avena monida (oat) biomass.

Chromium contamination of the environment has become an important issue due to the potential health threat it poses. Conventional technologies to clean up heavy metal ions from contaminated waters have been utilized, but these technologies are not cost-effective. However, the use of agricultural waste byproducts for the removal of Cr(VI) from contaminated waters may be a new cost-effective alternative. Oat byproducts from the Juarez Valley in Mexico were studied for the ability to bind Cr(VI) under different temperature and time conditions. The metal binding ability of oat byproducts was calculated from experimental data collected at temperatures of 8, 26, and 54 degrees C, and time exposures of 1, 6, 24, 48, and 72 h at each temperature. These results showed that the binding of Cr(VI) to oat biomass increased as time and temperature increased. The bound chromium was recovered from the oat biomass by treatment with 0.2M HCl. Through the use of X-ray absorption spectroscopy, the reduction of Cr(VI) to Cr(III) was determined to occur by the oat byproducts. These results indicate that the use of agricultural waste byproducts could be a better alternative for the removal and subsequent reduction of Cr(VI) to Cr(III) from contaminated waters.