نتایج جستجو برای: mineral scale deposition
تعداد نتایج: 726595 فیلتر نتایج به سال:
In this paper, a laboratory chemical vapor deposition (CVD) reactor is described, which features an opposing screw rotating fluidized bed. The efficiently concentrates powdered reactants in the reaction zone while maintaining fluidization independent of powder properties. This allows for lab-scale CVD processing many small samples at high yields and without need re-adjustment parameters differe...
A re-examination of the El Dragón vein-type Se deposit using polarized light microscopy and scanning-electron microscopy combined with electron-microprobe analyses revealed the following results: the detection of (a) petříčekite, krut’aite and penroseite close to endmember composition; (b) a yet unknown mineral of the ideal composition CuNi2Se4; (c) intermediate members of the vaesite-pyrite so...
This review attempts to summarize the findings made available by the literature on the mineralization of bone. The types of bone, their structures and compositions, the nature and organization of organic and inorganic matter, the organic-inorganic relationships, and the mineralization mechanism itself, are the main topics of the present review. As in other hard tissues, bone mineralization occu...
Bone is a dynamic tissue which is continuously adapting not only to external mechanical stimuli but also to internal metabolic calcium demands. During normal bone remodeling, bone-resorbing osteoclasts release calcium from the bone and digest the collagenous bone matrix, after which bone-depositing osteoblasts form unmineralized collagen matrix, which subsequently mineralizes. The detailed mech...
An enigmatic stepwise increase in oxygen in the late Precambrian is widely considered a prerequisite for the expansion of animal life. Accumulation of oxygen requires organic matter burial in sediments, which is largely controlled by the sheltering or preservational effects of detrital clay minerals in modern marine continental margin depocenters. Here, we show mineralogical and geochemical evi...
A poorly understood aspect of bone biomineralization concerns the mechanisms whereby ions are sequestered from the environment, concentrated, and deposited in the extracellular matrix. In this study, we follow mineral deposition in the caudal fin of the zebrafish larva in vivo. Using fluorescence and cryo-SEM-microscopy, in combination with Raman and XRF spectroscopy, we detect the presence of ...
Bone mineral content of the mid forearm was measured by photon absorptiometry in 73 white singletons (36 boys, 37 girls) born between 18 and 43 weeks' gestation. Results obtained within two weeks of birth for liveborn infants were used to establish bone mineral deposition curves approximating normal in utero development. Results for stillborn infants indicated a retardation of bone mineralisati...
Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30-50% of ...
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