Zobrazeno 1 - 10
of 126
pro vyhledávání: '"Robert L. Folk"'
Publikováno v:
Microscopy Today. 16:58-61
Tiny (50-200 nm) spheroids were first discovered by Folk through SEM work on the hot springs of Viterbo Italy. He termed these small, spherical structures “nannobacteria,” and proposed that they may be important agents in precipitation of CaCO3,
Autor:
Robert L. Folk, E. Troy Rasbury
Publikováno v:
Carbonates and Evaporites. 22:113-122
In a caliche from west Texas, watermelon-shaped calcite crystals are coated with fibers of palygorskite/sepiolite clay, which also extend out into pore spaces as spiky filaments. Some filaments are smooth and capped by ovoid 30–100nm beads. Other f
Autor:
Robert L. Folk
Publikováno v:
Journal of Earth System Science. 114:369-374
Study of sedimentary pyrite in the form of framboids, euhedral crystals or metasomatic masses has revealed that their surfaces are commonly covered with spheroids of about 50 nm. This applies to all the examples studied, from modern to Proterozoic. T
Autor:
Jeri C. Rodgers, Virginia M. Miller, Brenda L. Kirkland, Sandra R. Severson, Robert L. Folk, Marineh Yagubyan, Vivek Kumar, George P. Rodgers, Franklin R. Cockerill, Todd E. Rasmussen, Ewa Rzewuska-Lech, John C. Lieske, Jon Charlesworth, Gerard Farell-Baril
Publikováno v:
American Journal of Physiology-Heart and Circulatory Physiology. 287:H1115-H1124
Mechanisms mediating vascular calcification remain incompletely understood. Nanometer scale objects hypothesized to be a type of bacteria (nanobacteria) are associated with calcified geological specimens, human kidney stones, and psammona bodies in o
Autor:
Robert L. Folk, Frances Westall
Publikováno v:
Precambrian Research
Precambrian Research, Elsevier, 2003, 126, pp.313-330. ⟨10.1016/S0301-9268(03)00102-5⟩
Precambrian Research, Elsevier, 2003, 126, pp.313-330. ⟨10.1016/S0301-9268(03)00102-5⟩
The microstructure of HF-etched samples of Early Archaean banded iron formations (BIFs) and cherts from the >3.7 b.y.-old Isua Greenstone Belt (southwestern Greenland) was investigated using high resolution scanning electron microscopy equipped with
Autor:
Robert L. Folk, Emma T. Rasbury
Publikováno v:
Terra Nova. 14:469-475
Spheroids in the size range of 30–200 nm coat sand grains on sediments around the island of Vulcano. They occur as single individuals, as ball-shaped clumps resembling biological colonies with radiating chains of bodies, and eventually merge into s
Autor:
Lawrence A. Taylor, Robert L. Folk
Publikováno v:
Meteoritics & Planetary Science. 37:1057-1069
In martian meteorite Allan Hills (ALH) 84001, this scanning electron microscope study was focused on the ferromagnesian minerals, which are extensively covered with nanometer-size bodies mainly 30-100 nm in diameter. These bodies range from spheres t
Autor:
Robert L. Folk, F. Leo Lynch
Publikováno v:
Sedimentology. 48:215-229
Modern ooids from Joulters Cay, when baked at 500 °C, turn various shades of black depending upon the organic content. Mucus-rich laminae occur at quasi-regular intervals of a few micrometres within the cortex. When mucus is still present, it turns
Autor:
Robert L. Folk
Publikováno v:
Sedimentary Geology. 126:47-55
Nannobacteria are abundant not only in normal marine limestones but also in other environments such as continental caliches, fresh-water streams, springs, water pipes, caves, etc. Cells are typically 50 to 200 nm in diameter.
Publikováno v:
Sedimentary Geology. 126:243-252
Scanning electron microscopy reveals an association between early dolomite in the Pennsylvanian Desert Creek (Paradox Fm.) and small (approximately 0.1 μm) nanometer-scale textures, termed `nannobacteria'. Three diagenetically distinct dolomites are