Experiments with dinitrogen-, nitrite-, nitrate-containing solutions were conducted without headspace in Ti reactors (200°C), borosilicate septum bottles (70°C) and HDPE tubes (22°C) in the presence of Fe and Ni metal, awaruite (Ni 80 Fe 20 ) and tetrataenite (Ni 50 Fe 50 ). In general, metals used in this investigation were more reactive than alloys toward all investigated nitrogen species. Nitrite and nitrate were converted to ammonium more rapidly than dinitrogen, and the reduction process had a strong temperature dependence. We concluded from our experimental observations that Hadean submarine hydrothermal systems could have supplied significant quantities of ammonium for reactions that are generally associated with prebiotic synthesis, especially in localized environments. Several natural meteorites (octahedrites) were found to contain up to 22 ppm N tot . While the oxidation state of N in the octahedrites was not determined, XPS analysis of metals and alloys used in the study shows that N is likely present as nitride (N 3-). This observation may have implications toward the Hadean environment, since, terrestrial (e.g., oceanic) ammonium production may have been supplemented by reduced nitrogen delivered by metal-rich meteorites. This notion is based on the fact that nitrogen dissolves into metallic melts.
Background: The harmful effects from inhalation of coal dust are well-documented. The prevalence of lung disease varies by mining region and may, in part, be related to regional differences in the bioavailable iron content of the coal. Pyrite (FeS 2 ), a common inorganic component in coal, has been shown to spontaneously form reactive oxygen species (ROS) (i.e., hydrogen peroxide and hydroxyl radicals) and degrade nucleic acids. This raises the question regarding the potential for similar reactivity from coal that contains pyrite. Experiments were performed to specifically evaluate the role of pyrite in coal dust reactivity. Coal samples containing various amounts of FeS 2 were compared for differences in their generation of ROS and degradation of RNA.
Inhalation of certain types of particulate matter can lead to lung disease. The reactivity of these particles and, in part, the pathologic responses that result are dictated by their physicochemical properties. The ability of particles to induce the generation of reactive oxygen species (ROS), especially hydroxyl radicals in vivo, is one property that has been correlated to the development of lung disease. Several minerals, such as quartz and asbestos, are known to generate hydroxyl radicals and cause lung disease, but many other minerals have never been tested. Here, we describe a technique employing yeast RNA as a probe to screen for mineral-generated hydroxyl radicals. The stability of RNA in the presence of hydrogen peroxide, ferrous iron, hydroxyl radicals, and several common minerals (quartz, albite, forsterite, fayalite, hematite, magnetite, coal, and pyrite) was examined. 3'-(p-Aminophenyl) fluorescein (APF) was used to verify mineral generation of ROS. RNA is stable in the presence of hydrogen peroxide, quartz, and albite; while it degrades in the presence of ferrous iron, hydroxyl radicals, and the other minerals. Coal and pyrite are the most reactive both in RNA degradation and hydroxyl radical generation. This noncellular technique provides a straightforward way to compare many different particles simultaneously. Those particles showing reactivity toward RNA using this method are high-priority candidates for further in vitro and possibly in vivo tests.
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