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Your search keyword '"A. Dowd"' showing total 190 results
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190 results on '"A. Dowd"'

1. Synchrotron X-ray microtomography, electron probe microanalysis, and NMR of toluene waste in cement

Author

Butler, Leslie G., Owens, John W., Cartledge, Frank K., Kurtz, Richard L., Byerly, Gary R., Wales, Andrew J., Bryant, Pamela L., Emery, Earl F., Dowd, Betsy, and Xie, Xiaogang

Subjects
Cement -- Research, Toluene -- Research, Environmental issues, Science and technology
Abstract

A report on vesicular structures, examined by X-ray, in combinations of cement and toluene.

Published
2000

2. Synchrotron X-ray Microtomography, Electron Probe Microanalysis, and NMR of Toluene Waste in Cement

Author

John W. Owens, Earl F. Emery, Betsy A. Dowd, Gary R. Byerly, Pamela L. Bryant, Xiaogang Xie, Richard L. Kurtz, Andrew J. Wales, Frank K. Cartledge, and Leslie G. Butler

Subjects
Cement, Magic angle, Chemistry, Analytical chemistry, General Chemistry, Electron microprobe, Microanalysis, Toluene, law.invention, Matrix (chemical analysis), Portland cement, chemistry.chemical_compound, law, Phase (matter), Environmental Chemistry, Nuclear chemistry
Abstract

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures, prepared with 1.22−3.58 wt % toluene. Three-dimensional imaging of the cured samples shows spherical vesicles, with diameters ranging from 20 to 250 μm; a search with EPMA for vesicles in the range of 1−20 μm proved negative. However, the total vesicle volume, as computed from the microtomography images, accounts for less than 10% of initial toluene. Since the cements were cured in sealed bottles, the larger portion of toluene must be dispersed within the cement matrix. Evidence for toluene in the cement matrix comes from 29Si MAS NMR spectroscopy, which shows a reduction in chain silicates with added toluene. Also 2H NMR of toluene-d8/cement samples shows high mobility for all toluene and thus no toluene/cement binding. A model that accounts for all observations follows: For loadings below about 3 wt %, most toluene is dispersed in the cement matrix, with a small fraction of the initial toluene phase separating fro...

Published
2000
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