PubMed · 8781245
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S S Abdel-Meguid. 1996. Structure determination using isomorphous replacement.. https://doi.org/10.1385/0-89603-259-0%3A153
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A new flame method of atomic absorption spectrometry is described. The liquid sample to be analyzed is transported as a high-speed liquid jet into a heated tube which is positioned in an air/acetylene flame. The jet is generated by means of an HPLC pump which feeds a smooth jet nozzle having a diameter of 50 microns or smaller. After traveling a distance of 10 cm, the liquid jet enters a small sample introduction hole, impacts onto the opposite inner wall of the tube furnace, and immediately vaporizes (jet impact vaporization, JIV). Both the complete introduction of the entire sample and the extended residence time inside the absorption volume result in an improvement in power of detection from 6- to 202-fold for 17 elements (Ag, As, Au, Bi, Cd, Cu, Hg, In, K, Pb, Pd, Rb, Sb, Se, Te, Tl, Zn). A standard deviation of 1.7-4.0% (n = 12, 50 microL) was achieved. Sample volumes between 10 microL and 1 mL have been investigated. For 50 microL sample volumes, the sampling frequency is 4/min. The new method can also be considered a simple, effective interface between HPLC and flame AAS.
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Lunar Prospector is providing a global map of the composition of the moon and analyzing the moon's gravity and magnetic fields. It has been in a polar orbit around the moon since 16 January 1998. Neutron flux data show that there is abundant H, and hence probably abundant water ice, in the lunar polar regions. Gamma-ray and neutron data reveal the distribution of Fe, Ti, and other major and trace elements on the moon. The data delineate the global distributions of a key trace element-rich component of lunar materials called KREEP and of the major rock types. Magnetic mapping shows that the lunar magnetic fields are strong antipodal to Mare Imbrium and Mare Serenitatis and has discovered the smallest known magnetosphere, magnetosheath, and bow shock complex in the solar system. Gravity mapping has delineated seven new gravity anomalies and shown that the moon has a small Fe-rich core of about 300 km radius.