منابع مشابه
Microbial origin of desert varnish.
Scanning electron microscopy and energy dispersive x-ray analyses of desert varnish reveal that microorganisms concentrate ambient manganese that becomes greatly enhanced in brown to black varnish. Specific characteristics of desert varnish and of varnish bacteria support a microbial origin for manganese-rich films. Varnish microbes can be cultured and produce laboratory manganese films. Accord...
متن کاملBacterial contamination of cavity varnish.
The present investigation was undertaken to determine whether cavity varnish can serve as a bacterial reservoir. Twenty-eight samples of cavity varnish were collected From bottles in use in a clinic and two From previously unopened bottles of the material. Samples were grown on a variety of media, both aerobically and anaerobically. Results indicated growth in 25 of 30 samples. The two Freshly ...
متن کاملAstrobiological implications of rock varnish in Tibet.
The study of terrestrial geomicrobiology and its relationship to rock weathering processes is an essential tool in developing analogues for similar processes that may have occurred on Mars. Most studies of manganese-enhanced rock varnish have focused on samples taken from warm arid desert regions. Here, we examine samples obtained from eolian-abraded lava flows of the 4700-4800 m high Ashikule ...
متن کاملMicrobial Fossils Detected in Desert Varnish
Introduction: Mars Global Surveyor Thermal Emission Spectrometer data indicate regions with significant levels of hematite (_Fe2O3). Fe-oxides, like hematite, can form as aqueous mineral precipitates and as such may preserve microscopic fossils or other biosignatures. Several potential terrestrial analogues to martian hematite like hydrothermal vents have preserved microfossils [1]. Microbial f...
متن کاملOxidation State of Manganese in Rock Varnish
Rock varnish is generally understood to be a 5-500 micrometer thick nanostratigraphic coating consisting of approximately 70% clay glued together by 30% iron and manganese oxides, which forms on the surfaces of rocks in most semi-arid to hyper-arid climates. Many investigators believe that manganese exists in rock varnish mainly as birnessite, and that varnish has at least a partial biological ...
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ژورنال
عنوان ژورنال: The Chemist’s Section of the Cotton Oil Press
سال: 1921
ISSN: 0095-9774
DOI: 10.1007/bf03039842