993 resultados para 204-1249H
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The grain sizes of gas hydrate crystallites are largely unknown in natural samples. Single grains are hardly detectable with electron or optical microscopy. For the first time, we have used high-energy synchrotron diffraction to determine grain sizes of six natural gas hydrates retrieved from the Bush Hill region in the Gulf of Mexico and from ODP Leg 204 at the Hydrate Ridge offshore Oregon from varying depth between 1 and 101 metres below seafloor. High-energy synchrotron radiation provides high photon fluxes as well as high penetration depth and thus allows for investigation of bulk sediment samples. Gas hydrate grain sizes were measured at the Beam Line BW 5 at the HASYLAB/Hamburg. A 'moving area detector method', originally developed for material science applications, was used to obtain both spatial and orientation information about gas hydrate grains within the sample. The gas hydrate crystal sizes appeared to be (log-)normally distributed in the natural samples. All mean grain sizes lay in the range from 300 to 600 µm with a tendency for bigger grains to occur in greater depth. Laboratory-produced methane hydrate, aged for 3 weeks, showed half a log-normal curve with a mean grain size value of c. 40 µm. The grains appeared to be globular shaped.
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National Highway Traffic Safety Administration, Washington, D.C.
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Mode of access: Internet.
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"Op. 204, no. 3"--Cover.
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National Highway Traffic Safety Administration, Washington, D.C.
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Report -- Appendix A. Board minutes -- App. B. Witness statements & releases -- App. C. Apollo operations handbook -- App. D. Panel reports -- App. E. Management and organization -- App. F. Schedule of physical evidence -- App. G. Addenda and corrigenda.
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Mode of access: Internet.
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Spine title: Alaska 204(c) land withdrawals.
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Mode of access: Internet.
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"May 1982."
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Includes index.
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Includes indexes.
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"June 1972."