Many advances have been made in radiocarbon dating of bone organics, but research on 14C dating of bone inorganic carbon has lagged significantly behind. Using mammoth bone, enamel, and tusk from the Dent and Murray Springs Clovis sites, experiments with the Haas and Banewicz technique of bone apatite dating by step heating demonstrate that accurate radiocarbon ages can be produced from bone ap...

Abstract The corrosion behavior of environmental barrier coatings (EBCs) directly affects the service life and stability ceramic matrix composite (CMC) structural parts in aero-engines. silicon carbide (SiC) whisker toughening phase c-AlPO 4 bonding are firstly used to improve novel tri-layer Yb 2 Si O 7 /mullite/SiC EBCs burner rig test. formation penetrating cracks coating caused failure at 1...

introduction iron-apatite ore deposits well known as kiruna iron type formed in association with calc-alkaline volcanism from proterozoic to tertiary (hitzman et al., 1992). liquid immiscibility in an igneous system was proposed to explain the formation of the iron oxides accompanying apatite in mineralized zones (förster and jafarzadeh, 1994; daliran, 1999). the mode of ore formation however, ...

Surface modifications of glass-reinforced hydroxyapatite composites immersed in a simulated physiological solution were studied using X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. In the first stages of the apatite formation process, calcium and silicon ions were leached out from the surface of the composites. After 12 days of immersion...

Apatite contains only traces of uranium, yet as apatite is a minor constituent in most rocks and the major constituent of a few very large deposits, it accounts, paradoxically, for both dispersal and concentration of uranium in nature. Uranium typically makes up 0.001 to 0.01 percent of primary igneous apatite and 0.005 to 0.02 percent of sedimentary marine apatite. Marine reworked apatite beco...

the study area is located about 3 km southwest of the hormoz island in the hormozgan province, in the persian gulf. the main rock units in the region consist of a highly altered acidic pluton cratophyre, which is responsible for apatite formation, diabasic dike, marl and altered basalt. apatite is the only phosphate mineral in the hormoz island, which has accumulated ree in its crystal structur...

Synthetic A-type carbonated apatite prepared in controlled conditions was irradiated at room temperature with 60Co gamma rays. The ESR spectrum was associated to axial CO2- and orthorhombic CO3- species. Radicals used as dose markers in biological apatites are long-lived paramagnetic species. The stability of the post-irradiation signal of A-type apatite was investigated for almost 2 years. Mea...

In this study, randomly oriented hydroxyethyl cellulose/polyvinyl alcohol (HEC/PVA) nanofibers were fabricated by electrospinning. The blend solutions of HEC/PVA with different weight ratio of HEC to PVA were prepared using water as solvent to fabricate nanofibers. These nanofibrous scaffolds were coated with bone-like apatite by immersing into 10x simulated body fluid (SBF) for different time ...

having sufficient and accurate understanding about kinetics of phenomena, could be an important reason for further technological progresses. finding a white-box mathematical model for weight vs. time curves of electrophoretic deposition (epd) using large and small signal analysis has been studied thoroughly in the present investigation. weight-time curves of nano-mullite suspension have been tr...

High-alumina coal fly ash (HAFA: 45% Al2O3 and 40% SiO2) is regarded as a special solid waste that generated from power plants in northwestern China. It an important substitute for bauxite applied to prepare mullite-based ceramics. In this work, hydrometallurgy–pyrometallurgy synergistic process proposed resolve the lower Al2O3/SiO2 mass ratio (Al/Si) degree of crystallinity can promote formati...