نتایج جستجو برای: meteoritic iron
تعداد نتایج: 143039 فیلتر نتایج به سال:
Introduction: Organic compounds may survive beneath the surface or at the poles of the Moon. If so, at least a fraction of such compounds were probably delivered by asteroids and possibly comets. To the extent that inputs of carbon from different sources might vary as a function of geographic location and composition of crustal materials, future studies can advance our understanding of the orig...
Atom-probe tomography (APT) is currently the only analytical technique that, due to its spatial resolution and detection efficiency, has the potential to measure the carbon isotope ratios of individual nanodiamonds. We describe three different sample preparation protocols that we developed for the APT analysis of meteoritic nanodiamonds at sub-nm resolution and present carbon isotope peak ratio...
Plagioclase feldspar, clinopyroxene, and ilmenite in a polished thin section of a type A crystalline rock were analyzed. The clinopyroxene grains are compositionally variable, and both high Ca and low Ca phases are present. The plagioclase is compositionally homogeneous. The ilmenite is chemically homogeneous except for occasional, small areas of high local chromium concentration. Accessory min...
Microorganisms are believed to create microenvironments leading to reaction products not predictable from equilibrium thermodynamics and to unique biomineral morphologies. Unambiguous evidence for such environments is, however, rare in natural samples. We have used scanning transmission x-ray microscopy and spectromicroscopy at the sub-40-nm scale, coupled with transmission electron microscopy,...
The study of meteoritic organic compounds provides a unique window into the chemical inventory of the early Solar System and prebiotic chemistry that may have been important for the origin of life on Earth. Multiple families of organic compounds have been extracted from the Murchison meteorite, which is one of the most thoroughly studied carbonaceous chondrites. The amino acids extracted from M...
Ebert et al. have submitted a manuscript on observations of meteoritic particles in the UTLS region of the polar vortex. While meteoritic material has long been know to be a component of the upper atmosphere and that that material must follow general stratospheric circulation downward through the vortex, these are nice observations that enhance our knowledge of this area. This paper should be p...
Carbon-containing meteorites provide a natural sample of the extraterrestrial organic chemistry that occurred in the solar system ahead of life's origin on the Earth. Analyses of 40 years have shown the organic content of these meteorites to be materials as diverse as kerogen-like macromolecules and simpler soluble compounds such as amino acids and polyols. Many meteoritic molecules have identi...
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