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Journal articles on the topic 'Fluorapatit'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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1

Simon, Paul, Caren Göbel, Wilder Carrillo-Cabrera, Petr Formánek, Dorin Geiger, Reiner Ramlau, Harald Tlatlik, Jana Buder, and Rüdiger Kniep. "Fluorapatit-Gelatine-Komposite: Biomimetische Morphogenese und Realstruktur." Zeitschrift für anorganische und allgemeine Chemie 630, no. 11 (September 2004): 1760. http://dx.doi.org/10.1002/zaac.200470133.

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2

Rabis, Annegrit, Ulrich Schwarz, Margit Gruner, Susanne Busch, Jana Buder, Harald Tlatlik, Frank Steglich, and Rüdiger Kniep. "NMR-spektroskopische Untersuchungen an Gelatine, Gelatine/Phosphat und Fluorapatit-Gelatine-Komposit." Zeitschrift für anorganische und allgemeine Chemie 630, no. 11 (September 2004): 1754. http://dx.doi.org/10.1002/zaac.200470122.

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3

Kniep, Rüdiger, and Susanne Busch. "Biomimetisches Wachstum und Selbstorganisation von Fluorapatit-Aggregaten durch Diffusion in denaturierten Kollagen-Matrices." Angewandte Chemie 108, no. 22 (November 18, 1996): 2788–91. http://dx.doi.org/10.1002/ange.19961082208.

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4

Tlatlik, Harald, Paul Simon, Agnieszka Kawska, Dirk Zahn, and Rüdiger Kniep. "Biomimetische Fluorapatit-Gelatine-Nanokomposite: Vorstrukturierung von Gelatine-Matrices durch Ionenimprägnierung und Auswirkungen auf die Formentwicklung." Angewandte Chemie 118, no. 12 (March 13, 2006): 1939–44. http://dx.doi.org/10.1002/ange.200503610.

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5

Manca, S. G., N. Urquiza, and E. J. Baran. "Über den Einbau von AI(III), Ga(III) und In(III) in das Calcium-Fluorapatit-Gitter." Zeitschrift für Naturforschung B 46, no. 1 (January 1, 1991): 129–32. http://dx.doi.org/10.1515/znb-1991-0124.

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In order to determine the effect of Al(III), Ga(III) and In(III) on the inorganic phase of bone, a model study has been undertaken, investigating a series of fluoroapatites in which part of the Ca(II) ions were substituted be these cations. Diffractometric and spectroscopic studies show that low concentrations of the incorporated metals neither affect the crystallographic characteristics nor the strength of the P - O bonds of these apatitic materials.
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6

Wang, Xianchen, Qin Zhang, Song Mao, and Wei Cheng. "A Theoretical Study on the Electronic Structure and Floatability of Rare Earth Elements (La, Ce, Nd and Y) Bearing Fluorapatite." Minerals 9, no. 8 (August 20, 2019): 500. http://dx.doi.org/10.3390/min9080500.

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Calcium atoms are often replaced by rare earth elements (REEs) in the lattice of fluorapatite (Ca10F2(PO4)6), making the phosphate ore an important potential rare earth resource. In this paper, the electronic properties of REEs (La, Ce, Nd and Y) bearing fluorapatite crystals have been investigated by density functional theory. Results of calculation indicated that the existence of REEs increased the cell parameters of fluorapatite in varying degrees. The REEs substitution made the Fermi level of fluorapatite to move to higher energy levels, making it easier to accept electrons. Except for Y, all the other REEs (La, Ce and Nd) showed that the electronic state mainly exists in the valence band. The Fermi level of REEs were mainly contributed by La5d, Ce4f, Nd4f and Y4d, respectively. The Mulliken values of REE–F and REE–O bonds in REEs-bearing fluorapatites were larger than those of Ca–F and Ca–O bonds in the perfect crystal, and the values of Y–F and Y–O bonds were the largest. The results of interaction between fluorapatite and oleic acid by frontier molecular orbital analysis suggested that the substitution of REEs can improve the reactivity of fluorapatite with oleic acid.
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Manca, S. G., N. Urquiza, and E. J. Baran. "Notizen: Über den Einbau vierwertiger Kationen in das Calcium-Fluorapatit-Gitter / Incorporation of Tetravalent Cations in the Calcium Fluoroapatite Lattice." Zeitschrift für Naturforschung B 46, no. 12 (December 1, 1991): 1723–24. http://dx.doi.org/10.1515/znb-1991-1224.

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In order to determine the effect of tetravalent cations on the inorganic phase of hard tissues, a model study has been undertaken, investigating a series of fluoroapatites in which part of the Ca(II) ions were substituted by Th(IV), Zr(IV) or Hf(IV). Diffractometric and vibrational spectroscopic studies show that low concentrations of the incorporated metals neither affect the crystallographic characteristics nor the strength of the P—O bonds of these apatitic materials.
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8

Myšľan, Pavol, Peter Ružička, Tomáš Mikuš, and Miroslav Hain. "3D distribúcia minerálnych inklúzií v granátoch z lokalít Lesné - Potičky a Beňatinská voda (Slovenská republika)." Bulletin Mineralogie Petrologie 28, no. 2 (2020): 246–60. http://dx.doi.org/10.46861/bmp.28.246.

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Visualization of garnets and their mineral inclusions was performed by X-ray microtomography by reconstructing 3D image from 1800 measured 2D X-ray projections. Visualization procedure of 3D distribution of mineral inclusions was based on the different absorption of X-ray radiation between the host garnet and mineral inclusions. 3D visualization provided a realistic picture of a distribution of the 126 identified mineral inclusions in garnet from rhyolite and rhyodacite Beňatinská voda and 21 inclusions in garnet from Lesné - Potičky (Slovak Republic). Composition of garnet from locality Lesné - Potičky is Alm71.0-73.7Prp8.3-9.0Grs14.7-16.6 and from locality Beňatinská voda is Alm72.1-73.2 Prp5.5-5.9Grs18.3-19.4. Mineral inclusions in garnets from locality Lesné - Potičky are represented by fluorapatite, zircon, ilmenite, annite and magmatic melts preserved in the form of glass inclusions trapped in apatite inclusions. Mineral inclusions in garnets from locality Beňatinská voda are represented by fluorapatite, zircon and plagioclase An78.53-57.12. Chemical composition of zircons and fluorapatites are similar from both localities. Based on the chemical composition, the high-pressure origin of garnets associated with I-type magmas was confirmed.
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9

Tulyaganov, D. U., and R. Ya Khodakovskaya. "Glass-ceramic biomaterials based on the fluorapatite-anorthite and fluorapatitie-diopside systems." Glass and Ceramics 48, no. 5 (May 1991): 221–22. http://dx.doi.org/10.1007/bf00676772.

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10

Thủy, Nguyễn Thị, and Nguyễn Thị Hồng Nụ. "Characteristics of phosphate phase (fluorapatite and monazite) in the South Nam Xe carbonatites, Northwest Vietnam." Hue University Journal of Science: Earth Science and Environment 126, no. 4B (June 2, 2017): 97. http://dx.doi.org/10.26459/hueuni-jese.v126i4b.4293.

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<p>This paper presents characteristics of appearance and mineral chemistry of phosphate phase, including fluorapatite and monazite in the South Nam Xe carbonatite dykes in Northwest Vietnam. These minerals occur in both calcio- and ferrocarbonatites in various modes. Most of the fluorapatites in the calciocarbonatites are oblong to elongated, and have sharp contacts with calcite, aegirine and phlogopite suggesting their primary origin; whereas those in the ferrocarbonatites are commonly present in forms of stubby to perfect hexagonal prismatic crystals, which partly replaced by the monazite. The monazites in the ferrocarbonatites also occur as hundreds micro isolated crystals, which associated with ankerite, feldspar, magnetite and phlogopite.</p><p>Contents of fluor and rare earth elements (REE) are relatively high (F up to 4.26 wt.%; REE up to 5.19 wt.%) indicating a F- and REE-enriched precipitation for the carbonatites. The enrichment in light REEs in the fluorapatite is paired with an enrichment in Na, varying from 0.25 wt.% to 0.89 wt.%. The replacement of REE and Na for Ca in the fluorapatites, which leads to change in CaO/P<sub>2</sub>O<sub>5</sub> ratios might show an open system where Ca and P are added to areas of the fluorapatite depleted in light REE (LREE). REE contents in the monazite show a very limited variation, and are mainly composed of La, Ce and Nd (La<sub>2</sub>O<sub>3</sub> = 21.09-22.72 wt.%, Ce<sub>2</sub>O<sub>3</sub> = 32.82-33.35 wt.%, Nd<sub>2</sub>O<sub>3</sub> = 6.96-8.20 wt.% in calciocarbonatite; La<sub>2</sub>O<sub>3</sub> = 16.61-17.39 wt.%, Ce<sub>2</sub>O<sub>3</sub> = 32.07-33.52 wt.%, Nd<sub>2</sub>O<sub>3</sub> = 8.92-10.94 wt.% in ferrocarbonatite). </p>
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11

Hill, Robert G., Adam Calver, Stephen Skinner, Artemis Stamboulis, and Robert V. Law. "A MAS-NMR and Combined Rietveldt Study of Mixed Calcium/Strontium Fluorapatite Glass-Ceramics." Key Engineering Materials 309-311 (May 2006): 305–8. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.305.

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Strontium is one of the most common substituents in apatite crystals. The presence and behavior of Sr in apatite-group phases are of considerable significance in biology. The present paper investigates the substitution of strontium for calcium in a glass-ceramic of the following composition 4.5SiO23Al2O31.5P2O54CaO1CaF2. The glasses were characterized using Differential Thermal Analysis (DTA), X-ray powder diffraction (XRD), neutron diffraction (ND) and 19F Resonance Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The all calcium glass crystallized to calcium fluorapatite (Ca5(PO4)3F). Substituting strontium partially for calcium resulted in the formation of a mixed strontium/calcium fluorapatites. In contrast complete substitution resulted in the formation of strontium fluorapatite. MAS-NMR showed the the F to be present as F-Ca(3) representing a fluoride ion surrounded by three Ca2+ ions in the all calcium glass and was present as F-Sr(3) in the all strontium glass. In the mixed glasses fluorine was present as FCa( 3), F-Ca(2)Sr, F-CaSr(2) and F-Sr(3). Ca had a higher tendency to occupy the F-M(3) sites than Sr which may reflect the higher charge to size ratio of Ca2+ relative to Sr2+ and its greater affinity for F- ions.
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12

Tlatlik, Harald, Paul Simon, Agnieszka Kawska, Dirk Zahn, Rüdiger Kniep, and Hannes Lichte. "Titelbild: Biomimetische Fluorapatit-Gelatine-Nanokomposite: Vorstrukturierung von Gelatine-Matrices durch Ionenimprägnierung und Auswirkungen auf die Formentwicklung / Intrinsic Electric Dipole Fields and the Induction of Hierarchical Form Developments in Fluorapatite–Gelatine Nanocomposites: A General Principle for Morphogenesis of Biominerals? (Angew. Chem. 12/2006)." Angewandte Chemie 118, no. 12 (March 13, 2006): 1853. http://dx.doi.org/10.1002/ange.200690040.

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13

Reyes Jaimes, L. J., H. A. González Romero, A. Sandoval Amadora, D. Y. Peña Ballesteros, and H. A. Estupiñán Durán. "Evaluación de la degradación de superficies de fluorapatita mediante técnicas electroquímicas. (Degradation Assessment of Fluorapatite Surfaces using Electrochemical Techniques)." CIENCIA EN DESARROLLO 6, no. 1 (July 7, 2015): 33. http://dx.doi.org/10.19053/01217488.3647.

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ResumenSe evaluó el efecto del pH de fluido corporal simulado en la formación de apatitas y en la degradación de superficies de la aleación Ti6Al4V recubiertas con Fosfato de Calcio mediante la técnica de lectrodeposición catódica. Como variables de estudio se tomaron el pH del fluido corporal simulado y el tiempo de inmersión de los recubrimientos. Mediante microscopia electrónica de barrido, espectroscopia de energía dispersiva, difracción de rayos X y absorción atómica se pudo corroborar la formación de apatitas, y la degradación de los recubrimientos se evaluó mediante Espectroscopia de impedancia electroquímica y curvas de polarización potenciodinámicas. Los resultados obtenidos muestran que los recubrimientos tenían altas concentraciones de Fluorapatita (Ca5(PO4)3F) y que su formación se ve favorecida a medida que el pH del fluido corporal simulado y el tiempo de inmersión aumenta. Por otra parte, se obtuvo que las muestras evaluadas a pH de 7,2 son menos estables termodinámicamente, sin embargo, las evaluadas a 7,6 presentan una superficie más activa, por lo que se obtiene una mayor velocidad de degradación. AbstractThe pH eect of a Simulated Body Fluid in the apatite formation and the degradation of the Ti6Al4V alloy surfaces, coated by calcium phosphate obtained through cathodic electrodeposition was evaluated. The simulated body fluid pH and the coating immersion time were taken as variables. The formation of apatite was corroborated by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X Ray Diraction and Atomic Absorption Techniques. The coating degradation was assessed by the Electrochemical Impedance Spectroscopy and the Potential Dynamic Polarization Curves. The results have shown that the coatings had high concentrations of fluorapatite (Ca5(PO4)3F) and its formation was favored as the simulated body fluid pH and the immersion time increases. Moreover, it was found that the coatings samples evaluated at pH 7.2 were less thermodynamically steady, however, the evaluated coating at pH 7.6 exhibited a more active surface, so that a higher rate of degradation is obtained.
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14

Kuo, Tsung-Yuan, Chi-Sheng Chien, Cheng-Wei Liu, and Tzer-Min Lee. "Comparative investigation into effects of ZrO2 and Al2O3 addition in fluorapatite laser-clad composite coatings on Ti6Al4V alloy." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 233, no. 2 (December 10, 2018): 157–69. http://dx.doi.org/10.1177/0954411918816113.

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Composite coatings consisting of fluorapatite mixed with 20 wt% yttria (3 mol%) stabilized cubic phase zirconia (c-ZrO2, 3Y-TZP) or 20 wt% alumina (α-Al2O3) were deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system. The interface morphology, phase composition, micro-hardness and biological properties of the two coatings were examined and compared. The results showed that the fluorapatite/Al2O3 specimen underwent a greater inter-diffusion at the interface between the coating layer and the transition layer than the fluorapatite/ZrO2 specimen. During the cladding process, the ZrO2 and Al2O3 components of the coating were completely decomposed or underwent phase transformation. In addition, the fluorapatite was partially decomposed. For both specimens, the coating layers contained fluorapatite, CaF2 and CaTiO3 phases. The coating layer of the fluorapatite/ZrO2 specimen additionally contained TTCP, CaO, CaZrO3 and m-ZrO2 (monoclinic phase), while that of the fluorapatite/Al2O3 specimen contained β-TCP, CaAl2O4 and θ-Al2O3. The average micro-hardness of the fluorapatite/ZrO2 coating layer (1300 HV) was approximately 200 HV higher than that of the fluorapatite/Al2O3 coating layer (1100 HV). Both specimens generated dense bone-like apatite following immersion in simulated body fluid for 3 days. In other words, both specimens had a good in vitro bioactivity. However, the fluorapatite/ZrO2 specimen showed a better initial attachment and spread of osteoblast-like osteosarcoma MG63 cells than the fluorapatite/Al2O3 specimen in in vitro biocompatibility tests performed for 24 h.
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Gall, Quentin, William J. Davis, David G. Lowe, and Quinn Dabros. "Diagenetic apatite character and in situ ion microprobe U–Pb age, Keeseville Formation, Potsdam Group, New York State." Canadian Journal of Earth Sciences 54, no. 7 (July 2017): 785–97. http://dx.doi.org/10.1139/cjes-2016-0195.

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An occurrence of diagenetic fluorapatite cement is documented within the Cambro-Ordovician Keeseville Formation, Potsdam Group, near Chateaugay in New York State. The fluorapatite cement occurs as stratiform layers within ephemeral fluvial quartz arenites, which have been reworked by aeolian processes prior to burial. The paragenetic sequence includes the following: compaction of dust-rimmed grains → quartz cementation → minor kaolinite → fluorapatite cementation followed by secondary dissolution porosity and telogenetic hematite cementation. Mesogenetic illitization of kaolinite may have taken place prior to or following fluorapatite cementation. The fluorapatite occurs as elongated bladed crystals that characteristically contain ladder-like, inclusion-rich cores running parallel to crystal length, surrounded by clearer rims, and larger blocky crystals towards the middle of interstices. In situ SHRIMP analyses of blocky fluorapatite crystals yield a U–Pb age of 486 ± 29 Ma, indicating that the cement formed during mesogenetic burial processes and (or) during fluid flow driven by Taconic orogenic events. There is no obvious source of phosphorous for the fluorapatite cement within the Potsdam Group, but phosphorous-rich lithologies are known from the adjacent basement of the Adirondack Dome. Phosphorous-rich fluids may have been derived from these basement lithologies. The occurrence of the rare fluorapatite cement in the Keeseville Formation adjacent to the Chateaugay Lake Fault raises the possibility that alkaline phosphatic fluids were focused within the fault and migrated laterally away from the fault into the host Keeseville Formation to form stratiform fluorapatite cement in the sandstone.
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Morin, Guillaume, Thierry Allard, Etienne Balan, Philippe Ildefonse, and Georges Calas. "Native Cd+ in sedimentary fluorapatite." European Journal of Mineralogy 14, no. 6 (November 25, 2002): 1087–94. http://dx.doi.org/10.1127/0935-1221/2002/0014-1087.

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17

Wang, Gaoqi, Yunkai Li, Shouren Wang, Xuefeng Yang, and Yujing Sun. "Two-Body and Three-Body Wear Behavior of a Dental Fluorapatite Glass-Ceramic." Coatings 9, no. 9 (September 13, 2019): 580. http://dx.doi.org/10.3390/coatings9090580.

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As a veneering porcelain coating of dental prosthesis, two-body and three-body wear behavior of dental glass-ceramic with the main crystalline phase of fluorapatite has not been comprehensively studied. In this work, a self-made fluorapatite glass-ceramic was synthesized and the mechanical and tribological performances of the glass-ceramic were tested, comparing with a commercial feldspathic glass-ceramic. The friction and wear experiments were performed between disk-shaped glass-ceramics and natural teeth in two-body (dry, water, saliva) and three-body (slurry) modes, respectively. Results showed that good mechanical properties of fluorapatite glass-ceramic can be achieved by the sintering process. In both two-body and three-body modes, the fluorapatite glass-ceramic had a smaller friction coefficient and wear rate and caused less damage on antagonistic teeth than the feldspathic glass-ceramic. The greater mechanical properties give fluorapatite glass-ceramic a better wear resistance and reduce the adhesive wear.
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18

Malysheva, Khrystyna, Konrad Kwaśniak, Iaroslav Gnilitskyi, Adriana Barylyak, Viktor Zinchenko, Amir Fahmi, Olexandr Korchynskyi, and Yaroslav Bobitski. "Functionalization of Polycaprolactone Electrospun Osteoplastic Scaffolds with Fluorapatite and Hydroxyapatite Nanoparticles: Biocompatibility Comparison of Human Versus Mouse Mesenchymal Stem Cells." Materials 14, no. 6 (March 10, 2021): 1333. http://dx.doi.org/10.3390/ma14061333.

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A capability for effective tissue reparation is a living requirement for all multicellular organisms. Bone exits as a precisely orchestrated balance of bioactivities of bone forming osteoblasts and bone resorbing osteoclasts. The main feature of osteoblasts is their capability to produce massive extracellular matrix enriched with calcium phosphate minerals. Hydroxyapatite and its composites represent the most common form of bone mineral providing mechanical strength and significant osteoinductive properties. Herein, hydroxyapatite and fluorapatite functionalized composite scaffolds based on electrospun polycaprolactone have been successfully fabricated. Physicochemical properties, biocompatibility and osteoinductivity of generated matrices have been validated. Both the hydroxyapatite and fluorapatite containing polycaprolactone composite scaffolds demonstrated good biocompatibility towards mesenchymal stem cells. Moreover, the presence of both hydroxyapatite and fluorapatite nanoparticles increased scaffolds’ wettability. Furthermore, incorporation of fluorapatite nanoparticles enhanced the ability of the composite scaffolds to interact and support the mesenchymal stem cells attachment to their surfaces as compared to hydroxyapatite enriched composite scaffolds. The study of osteoinductive properties showed the capacity of fluorapatite and hydroxyapatite containing composite scaffolds to potentiate the stimulation of early stages of mesenchymal stem cells’ osteoblast differentiation. Therefore, polycaprolactone based composite scaffolds functionalized with fluorapatite nanoparticles generates a promising platform for future bone tissue engineering applications.
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19

Harlov, D. E., H. J. Förster, and C. Schmidt. "High P-T experimental metasomatism of a fluorapatite with significant britholite and fluorellestadite components: implications for LREE mobility during granulite-facies metamorphism." Mineralogical Magazine 67, no. 1 (February 2003): 61–72. http://dx.doi.org/10.1180/0026461036710084.

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AbstractA LREE-, Si-, S-enriched fluorapatite with ∼7.7 wt.% LREE2O3, 5.3 wt.% SiO2 and 3.5 wt.% SO3 from the Mushugai-Khuduk REE deposit, southern Mongolia, has been experimentally metasomatized in pure H2O at 900°C and 1000 MPa. Despite the high LREE content, inclusions or rim grains of monazite did not form during fluid-induced metasomatism. Under high-contrast BSE imaging, the reacted fluorapatite presents a mottled appearance with light, moderate and dark areas and hosts large fluid inclusions containing anhydrite as the solid phase. Dark areas show moderate depletion in all the LREE. Measurable HREE such as Gd and Y remain unchanged. In the areas of intermediate brightness, Ce and, to a lesser extent, La are moderately enriched relative to the original fluorapatite. In the light areas, Ce and La display strong enrichment, whereas the other LREE, Gd and Y remain little changed. In the dark areas, depletion in LREE is matched by depletion in Si and Na, satisfying the coupled substitution reactions Si4+; + (LREE)3+ = P5+ + Ca2+ and Na+ + (LREE)3+ = 2Ca2+. In the light areas, enrichment in LREE and P is accompanied by depletion in Si, Na and S, implying operation of two different coupled substitution reactions, namely: 2P5+ = Si4+ + S6+ and 2P5+ + LREE3+ = 2S6+ + Na+. In all areas, strong enrichment in F is accompanied by strong depletion in Cl and OH. The formation of large, fluid and anhydrite-filled inclusions associated with the LREE-enriched light areas is evidence of a negative volume change, combined with additional local dissolution of the fluorapatite. This occurred during the metasomatism of the original Cl- and OH-bearing fluorapatite to a nearly pure end-member fluorapatite. Local dissolution of fluorapatite in the space now occupied by the voids, combined with element remobilization from the body of the fluorapatite as a whole, provided the Ca and S needed for the formation of anhydrite as well as the P and LREE required for the enrichment of the bright areas.
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Sayenko, S. Yu. "Obtaining of strontium doped fluorapatite powders." Functional materials 22, no. 2 (June 30, 2015): 263–68. http://dx.doi.org/10.15407/fm22.02.263.

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21

Simon, Paul. "Fluorapatite-Gelatine Nanocomposites." Imaging & Microscopy 11, no. 1 (March 2009): 38–41. http://dx.doi.org/10.1002/imic.200990015.

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22

Cook, Robert B. "Connoisseurs's Choice: Fluorapatite." Rocks & Minerals 68, no. 2 (April 1993): 112–14. http://dx.doi.org/10.1080/00357529.1993.9926537.

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Csathó, Péter. "Kukorica P-hatásokat befolyásoló tényezők vizsgálata az 1960 és 2000 között publikált hazai szabadföldi kísérletek adatbázisán." Agrokémia és Talajtan 52, no. 3-4 (November 1, 2003): 455–72. http://dx.doi.org/10.1556/agrokem.52.2003.3-4.15.

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Amennyiben a talajok P-tartalma az agronómiailag indokolt szint fölé emelkedik, ugrásszeruen megnohet a talajból a felszíni vizekbe, ill. bizonyos körülmények között a felszín alatti vizekbe jutó foszfor mennyisége. A csatornák, patakok, folyók és tavak stb. vizének kritikus szint feletti P-koncentrációja az eutrofizáció felgyorsulásához vezethet. Az 1960-as évek közepétol a több mint két évtizedes talajgazdagító P-trágyázás (+20 és +40 kg/ha P2O5 többletek) következtében rohamosan javulni kezdett talajaink P-ellátottsága és az 1990-es évek elejére a szántóterület mintegy 2/3-a foszforral jól, vagy igen jól (túlzottan) ellátottá vált. 1990-tol kezdodoen a hazai P-mérlegek erosen negatívak, évi -10 és -20 kg/ha P2O5-hiányt mutatnak. A fejlett nyugat-európai országokban ma is erosen pozitívak a P-mérlegek. Annak ellenére, hogy a megnövekedett P-tartalmú talajok fokozott környezeti kockázatot jelentenek, hazánkban mind a mai napig az indokoltnál jóval kevesebb kutatás irányult a környezetvédelmi célú P-talajvizsgálatok hazai adaptációjára. A kérdéskör vizsgálata azért is kiemelten fontos, mivel Magyarország EU-csatlakozásának elofeltételeként, a városok szennyvíztisztítása megvalósul, felszíni vizeink pontszeru P-terhelése ily módon jelentosen csökken, másrészt nagyobb hangsúlyt kapnak a legnagyobb diffúz szennyezo forrás, a mezogazdasági eredetu P-terhelés csökkentésének lehetoségei. A P-megkötodés mértéke talajonként különbözo lehet. Mivel a szorpciós folyamat az agyagfrakcióhoz és az oxid-hidroxid frakciókhoz kötheto, a P-fixáció a nagy agyagtartalmú talajokban eroteljesebb. Ennek megfeleloen, a szervetlen kolloidokban szegény talajok P-megkötése gyenge. Általában véve, a 6,0 és 6,5 közötti pH(H2O)-értékek mellett legkisebb a P-megkötodés. Erosen savanyú talajokon alacsony oldékonyságú Fe- és Al-foszfátok (strengit, variscit), erosen meszes talajokon a szintén gyenge oldékonyságú Ca-foszfát vegyületek (oktokalcium-foszfát, hidroxiapatit, fluorapatit) képzodése jelzi az eroteljes P-megkötodést. Az összes P-terhelésbol a mezogazdasági terhelés részarányát 39 %-ra becsülik Dániában, 54 %-ra Norvégiában, 73 %-ra Svédországban, és 79 %-ra Finnországban. Becslések szerint Magyarországon 10 % az agrár P-terhelés aránya. Ez utóbbinak oka a lakossági terhelés rendkívül magas részaránya, a szennyvizeknek kezelés nélküli, közvetlen felszíni vizekbe való vezetése. A kutatóknak, talajvizsgáló laboratóriumoknak erofeszítéseket kell tenniük a könnyen oldható P-tartalmak, az értéküket befolyásoló talajtulajdonságok (pH, mészállapot, talaj fizikai félesége, szervesanyag-tartalom stb.) minél pontosabb meghatározására, a kalibráció minél pontosabb elvégzésére. A talaj könnyen oldható P-tartalmát az egyéb információkkal együtt (talajerózió, felszíni elfolyás, P-adag, és P-kijuttatás módja stb.) figyelembe kell venni a potenciális P-terhelés becslésekor.
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24

Osztoics, Erzsébet, Katalin Sárdi, István Sisák, András Osztoics, Marianna Magyar, and Péter Szűcs. "A mezőgazdasági területekről a felszíni vizekbe kerülő foszforterhelések." Agrokémia és Talajtan 52, no. 3-4 (November 1, 2003): 473–86. http://dx.doi.org/10.1556/agrokem.52.2003.3-4.16.

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Amennyiben a talajok P-tartalma az agronómiailag indokolt szint fölé emelkedik, ugrásszeruen megnohet a talajból a felszíni vizekbe, ill. bizonyos körülmények között a felszín alatti vizekbe jutó foszfor mennyisége. A csatornák, patakok, folyók és tavak stb. vizének kritikus szint feletti P-koncentrációja az eutrofizáció felgyorsulásához vezethet. Az 1960-as évek közepétol a több mint két évtizedes talajgazdagító P-trágyázás (+20 és +40 kg/ha P2O5 többletek) következtében rohamosan javulni kezdett talajaink P-ellátottsága és az 1990-es évek elejére a szántóterület mintegy 2/3-a foszforral jól, vagy igen jól (túlzottan) ellátottá vált. 1990-tol kezdodoen a hazai P-mérlegek erosen negatívak, évi -10 és -20 kg/ha P2O5-hiányt mutatnak. A fejlett nyugat-európai országokban ma is erosen pozitívak a P-mérlegek. Annak ellenére, hogy a megnövekedett P-tartalmú talajok fokozott környezeti kockázatot jelentenek, hazánkban mind a mai napig az indokoltnál jóval kevesebb kutatás irányult a környezetvédelmi célú P-talajvizsgálatok hazai adaptációjára. A kérdéskör vizsgálata azért is kiemelten fontos, mivel Magyarország EU-csatlakozásának elofeltételeként, a városok szennyvíztisztítása megvalósul, felszíni vizeink pontszeru P-terhelése ily módon jelentosen csökken, másrészt nagyobb hangsúlyt kapnak a legnagyobb diffúz szennyezo forrás, a mezogazdasági eredetu P-terhelés csökkentésének lehetoségei. A P-megkötodés mértéke talajonként különbözo lehet. Mivel a szorpciós folyamat az agyagfrakcióhoz és az oxid-hidroxid frakciókhoz kötheto, a P-fixáció a nagy agyagtartalmú talajokban eroteljesebb. Ennek megfeleloen, a szervetlen kolloidokban szegény talajok P-megkötése gyenge. Általában véve, a 6,0 és 6,5 közötti pH(H2O)-értékek mellett legkisebb a P-megkötodés. Erosen savanyú talajokon alacsony oldékonyságú Fe- és Al-foszfátok (strengit, variscit), erosen meszes talajokon a szintén gyenge oldékonyságú Ca-foszfát vegyületek (oktokalcium-foszfát, hidroxiapatit, fluorapatit) képzodése jelzi az eroteljes P-megkötodést. Az összes P-terhelésbol a mezogazdasági terhelés részarányát 39 %-ra becsülik Dániában, 54 %-ra Norvégiában, 73 %-ra Svédországban, és 79 %-ra Finnországban. Becslések szerint Magyarországon 10 % az agrár P-terhelés aránya. Ez utóbbinak oka a lakossági terhelés rendkívül magas részaránya, a szennyvizeknek kezelés nélküli, közvetlen felszíni vizekbe való vezetése. A kutatóknak, talajvizsgáló laboratóriumoknak erofeszítéseket kell tenniük a könnyen oldható P-tartalmak, az értéküket befolyásoló talajtulajdonságok (pH, mészállapot, talaj fizikai félesége, szervesanyag-tartalom stb.) minél pontosabb meghatározására, a kalibráció minél pontosabb elvégzésére. A talaj könnyen oldható P-tartalmát az egyéb információkkal együtt (talajerózió, felszíni elfolyás, P-adag, és P-kijuttatás módja stb.) figyelembe kell venni a potenciális P-terhelés becslésekor.
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25

Nikčević, I., V. Jokanović, M. Mitrić, Z. Nedić, D. Makovec, and D. Uskoković. "Mechanochemical synthesis of nanostructured fluorapatite/fluorhydroxyapatite and carbonated fluorapatite/fluorhydroxyapatite." Journal of Solid State Chemistry 177, no. 7 (July 2004): 2565–74. http://dx.doi.org/10.1016/j.jssc.2004.03.024.

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26

Nan, Nan, Yimin Zhu, Yuexin Han, and Jie Liu. "Molecular Modeling of Interactions between N-(Carboxymethyl)-N-tetradecylglycine and Fluorapatite." Minerals 9, no. 5 (May 6, 2019): 278. http://dx.doi.org/10.3390/min9050278.

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In this study, a flotation collector N-(carboxymethyl)-N-tetradecylglycine (NCNT) was introduced for the purpose of energy-saving, and its adsorption ability on a fluorapatite (001) surface was investigated by density functional theory calculation. The results of frontier molecular orbital analysis of NCNT and adsorption energy between NCNT and fluorapatite (FAp) showed that NCNT possessed better activity and stronger interactions in the reagent–FAp system than oleic acid (OA). A simulation model revealed that the adsorption positions of NCNT on the fluorapatite surface are calcium atoms, at which NCNT chemisorbed on (001) fluorapatite surface via a bidentate geometry involving the formation of two Ca–O bonds. Flotation experiments verified that NCNT had a good recovery of 92.27% on FAp at pH 3.5, which was slightly lower than OA. Moreover, NCNT was used at 16 °C, which was much lower than the OA’s service condition (25 °C).
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27

Dumańska-Słowik, Magdalena, Bartosz Budzyń, Wiesław Heflik, and Magdalena Sikorska. "Stability relationships of REE-bearing phosphates in an alkali-rich system (nepheline syenite from the Mariupol Massif, SE Ukraine)." Acta Geologica Polonica 62, no. 2 (June 1, 2012): 247–65. http://dx.doi.org/10.2478/v10263-012-0013-z.

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ABSTRACT Dumańska-Słowik, M., Budzyń, B., Heflik, W. and Sikorska, M. 2012. Stability relationships of REE-bearing phosphates in an alkali-rich system (nepheline syenite from the Mariupol Massif, SE Ukraine). Acta Geologica Polonica, 62 (2), 247-265. Primary REE-enriched fluorapatite and fluorbritholite-(Ce) in nepheline syenite from the Mariupol Massif (SE Ukraine), contain textural and chemical evidence of late- to post-magmatic metasomatic alteration. REE mobilization and replacement of the primary phases by fluid-mediated coupled dissolution-reprecipitation strongly depended on the distance between the altered minerals in the host rock. Fluorapatite and fluorbritholite-(Ce) forming individual pristine grains were partially replaced by the same phase with a new composition, resulting in the presence of patchy zoning in altered grains. The increased REE contents in altered fluorapatite rim domains are related to REE mobilization from the altered REE-depleted rim domains of the fluorbritholite-(Ce). The REEs were transported by a fluid with high F activity. The alteration of fluorapatite and fluorbritholite-(Ce) grains in contact resulted in the partial replacement of the primary phases by the same phase with a new composition, but also in the partial replacement of the fluorapatite by secondary monazite and fluorite. The REE mobilized from the fluorbritholite-(Ce) in the presence of a F-rich fluid in an alkali-rich system promoted formation of monazite as the new phosphate REE-host. The presence of secondary parisite in the altered domains of the fluorapatite and fluorbritholite-(Ce) indicates a CO 2 component in the fluid during metasomatic alteration.
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28

Alves, Felipe Emerson André, Reiner Neumann, Ciro Alexandre Ávila, and Fabiano Richard Leite Faulstich. "Monazite-(Ce) and xenotime-(Y) microinclusions in fluorapatite of the pegmatites from the Volta Grande mine, Minas Gerais state, southeast Brazil, as witnesses of the dissolution–reprecipitation process." Mineralogical Magazine 83, no. 4 (June 25, 2019): 595–606. http://dx.doi.org/10.1180/mgm.2019.43.

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AbstractFluorapatite with monazite-(Ce) and xenotime-(Y) microinclusions occurs in the lithium–caesium–tantalum pegmatite body A of the Volta Grande mine, Minas Gerais state, Southeast Brazil. The fluorapatite displays faint zoning, detected mainly by cathodoluminescence. Electron probe and laser ablation analyses indicate that zoning in the fluorapatite corresponds to variation in Mn and rare-earth element (REE) content. Such compositional variation is attributed to partial removal of the REE from the fluorapatite structure during a dissolution–reprecipitation process, forming monazite-(Ce) and xenotime-(Y) microinclusions in the REE-depleted zones of the fluorapatite. These inclusions exhibit an inherited geochemical signature, manifested by low Th and U concentrations when compared to monazite and xenotime crystallised from melts. Rhodochrosite and calcite inclusions are also associated with monazite-(Ce) and xenotime-(Y) and are probably products of the same process, recycling Ca, Mn, and CO32− from the fluorapatite through the following reaction: [Ca(5–2a–b–½x),Naa,(Y + REE)a,Mnb][(PO4)3–x(CO3)x(F)] + Fluid[a(2Ca2+ + P5+) + (x–b)(Ca2+) + H2O)] → [Ca5(PO4)3(F,OH)] + a[(Y + REE)PO4] + b[Mn(CO3)] + (x–b)[Ca(CO3)] + Fluid a[Na+].On the basis of new fluid-inclusion analyses, we propose that a hot (T > 204.5°C), salty (16 wt.% eq. NaCl, attributed to LiCl), hydrous fluid mediated the dissolution–reprecipitation of the fluorapatite. This fluid corresponds to similarly described Li-rich fluids which were suggested to have re-equilibrated the mineralogical assemblage at the Volta Grande mine.
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29

Loy, Chee W., Khamirul A. Matori, Norhazlin Zainuddin, Andrew E. Whitten, Christine Rehm, Liliana de Campo, Anna Sokolova, and Siegbert Schmid. "Crystallographic characterization of fluorapatite glass-ceramics synthesized from industrial waste." Powder Diffraction 32, S2 (September 5, 2017): S61—S65. http://dx.doi.org/10.1017/s088571561700094x.

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A series of phase transformations of a novel fluoroaluminosilicate glass forming a range of fluorapatite glass-ceramics on sintering are reported. The sintering process induces formation of fluorapatite, mullite, and anorthite phases within the amorphous silicate matrices of the glass-ceramics. The fluoroaluminosilicate glass, SiO2–Al2O3–P2O5–CaO–CaF2, is prepared from waste materials, such as rice husk ash, pacific oyster shells, and disposable aluminium cans. The thermally induced crystallographic and microstructure evolution of the fluoroaluminosilicate glass towards the fluorapatite glass-ceramics, with applications in dental and bone restoration, are investigated by powder X-ray diffraction and small-angle neutron-scattering techniques.
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30

Birski, Słaby, Chatzitheodoridis, Wirth, Majzner, Kozub-Budzyń, Sláma, Liszewska, Kocjan, and Zagórska. "Apatite from NWA 10153 and NWA 10645—The Key to Deciphering Magmatic and Fluid Evolution History in Nakhlites." Minerals 9, no. 11 (November 10, 2019): 695. http://dx.doi.org/10.3390/min9110695.

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Apatites from Martian nakhlites NWA 10153 and NWA 10645 were used to obtain insight into their crystallization environment and the subsequent postcrystallization evolution path. The research results acquired using multi-tool analyses show distinctive transformation processes that were not fully completed. The crystallization history of three apatite generations (OH-bearing, Cl-rich fluorapatite as well as OH-poor, F-rich chlorapatite and fluorapatite) were reconstructed using transmission electron microscopy and geochemical analyses. Magmatic OH-bearing, Cl-rich fluorapatite changed its primary composition and evolved toward OH-poor, F-rich chlorapatite because of its interaction with fluids. Degassing of restitic magma causes fluorapatite crystallization, which shows a strong structural affinity for the last episode of system evolution. In addition to the three apatite generations, a fourth amorphous phase of calcium phosphate has been identified with Raman spectroscopy. This amorphous phase may be considered a transition phase between magmatic and hydrothermal phases. It may give insight into the dissolution process of magmatic phosphates, help in processing reconstruction, and allow to decipher mineral interactions with hydrothermal fluids.
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31

Liferovich, R. P., and R. H. Mitchell. "Apatite-group minerals from nepheline syenite, Pilansberg alkaline complex, South Africa." Mineralogical Magazine 70, no. 5 (October 2006): 463–84. http://dx.doi.org/10.1180/0026461067050346.

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AbstractThe nepheline syenites of the Pilansberg alkaline complex (South Africa) have undergone extensive subsolidus equilibration and alteration with a deuteric Cl- and Na-rich fluid phase. Complex assemblages of secondary minerals result from the replacement of primary alummosilicates, rinkite, eudialyte and fluorapatite. The composition of apatite group minerals formed during these alteration processes reflects the Sr- and rare earth element (REE) content, Na/Cl ratio and pH of the deuteric fluids. Apatite-group minerals are observed to have formed in the following sequence: orthomagmatic fluorapatite; strontian britholite-(Ce); strontian fluorapatite; Sr-apatite; REE-rich Sr-apatite; Sr-Na-REE- rich minerals approaching the stoichiometry of belovite-(Ce) and deloneite-(Ce); britholite-(Ce). Increasing alkalinity of the deuteric fluids is reflected by increasing amounts of Sr replacing Ca in apatite and culminates in the formation of Sr apatite containing 62.1 wt.% SrO (∼4.17 a.p.f.u. Sr). Pilansberg apatite-group minerals form a near-complete solid solution between fluorapatite and a fluorine analogue of Sr apatite with limited solution towards belovite-(Ce), Si-rich belovite-(Ce) and strontian britholite-(Ce).
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32

Schumann, Dirk, Robert F. Martin, Sebastian Fuchs, and Jeffrey de Fourestier. "Silicocarbonatitic melt inclusions in fluorapatite from the Yates prospect, Otter Lake, Québec: Evidence of marble anatexis in the central metasedimentary belt of the Grenville Province." Canadian Mineralogist 57, no. 5 (September 30, 2019): 583–604. http://dx.doi.org/10.3749/canmin.1900015.

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Abstract We have investigated a locality very well known to mineral collectors, the Yates U-Th prospect near Otter Lake, Québec. There, dikes of orange to pink calcite enclose euhedral prisms of fluorapatite, locally aligned. Early investigators pointed out the importance of micro-inclusions in the prisms. We describe and image the micro-inclusions in two polished sections of fluorapatite prisms, one of them with a millimetric globule of orange calcite similar to that in the matrix. We interpret the globule to have been an inclusion of melt trapped during growth. Micro-globules disseminated in the fluorapatite are interpreted to have crystallized in situ from aliquots of the boundary-layer melt enriched in constituents rejected by the fluorapatite; the micro-globules contain a complex jigsawed assemblage of carbonate, silicate, and sulfate minerals. Early minerals to crystallize are commonly partly dissolved and partly replaced by lower-temperature phases. Such jigsawed assemblages seem to be absent in the carbonate matrix sampled away from the fluorapatite prisms. The pressure and temperature attained at the Rigolet stage of the Grenville collisional orogeny were conducive to the anatexis of marble in the presence of H2O. The carbonate melt is considered to have become silicocarbonatitic by assimilation of the enclosing gneisses, which were also close to their melting point. Degassing was important, and the melt froze quickly. The evidence points to a magmatic origin for the carbonate dikes and the associated clinopyroxenite, rather than a skarn-related association.
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33

Silva, G. P. S., M. C. S. Nunes, C. Ulsen, R. Künzel, E. M. Yoshimura, and N. M. Trindade. "Thermoluminescence of fluorapatite mineral." Journal of Luminescence 231 (March 2021): 117802. http://dx.doi.org/10.1016/j.jlumin.2020.117802.

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34

Kherifi, D., H. Belhouchet, S. Ramesh, K. Y. Sara Lee, A. Kenzour, S. Djoualah, M. K. G. Abbas, Y. H. Wong, and S. Ramesh. "Sintering behaviour of fluorapatite–silicate composites produced from natural fluorapatite and quartz." Ceramics International 47, no. 12 (June 2021): 16483–90. http://dx.doi.org/10.1016/j.ceramint.2021.02.216.

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35

Priha, Outi K., Tuija H. Sarlin, Mona E. Arnold, and Päivi Kinnunen. "Enrichment and Isolation of Phosphorus Solubilizing Bacteria." Advanced Materials Research 825 (October 2013): 62–65. http://dx.doi.org/10.4028/www.scientific.net/amr.825.62.

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The aim of this study was to enrich phosphorus solubilizing microorganisms from high-phosphorus iron ores, apatite ores and phosphogypsum waste. Phosphorus solubilizing microorganisms can be utilized in dephosphorization of high-phosphorus iron ores and in phosphorus leaching from fluorapatite ores. Low grade fluorapatite ore (3.6% P, pH 6.8), fluorapatite concentrate (13% P, pH 8.3), phosphogypsum waste (0.7% P, pH 2.3), iron ore 1 (0.19% P, pH 7.6) and iron ore 2 (0.18% P, pH 7.6) were used as potential sources of phosphorus solubilizing microorganisms. The samples were cultured in NBRIP media at pH 5 and 8 with either glucose or sucrose as a carbon source, and in modified 9K media at pH 1.5 and 2.5 for 3 weeks. Phosphorus solubilizing bacteria were enriched only from the fluorapatite concentrate at the pH of 8. The four obtained heterotrophic isolates were identified by 16S rRNA gene sequencing, and were shown to be closest related to Burkholderia fungorum. These results indicate that the diversity of culturable phosphorus solubilizing bacteria present in apatite and iron ores is relatively low. The isolated Burkholderia strain showed phosphorus solubilizing potential.
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36

Zhao, Jun, Zhijie Chen, Haibin Zuo, Jingsong Wang, and Qingguo Xue. "Research on Reaction Mechanism of Vacuum Carbon Thermal Reduction and Dephosphorization in High Phosphate Iron Ore." Metals 8, no. 12 (December 1, 2018): 1003. http://dx.doi.org/10.3390/met8121003.

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According to the mineral composition characteristics of high-phosphorus iron ore, the reaction mechanism of fluorapatite was investigated using pure substance and gangue under vacuum carbon thermal reduction (VCTR) conditions. The effects of reduction temperature, basicity, and C/O ratio on the metallization ratio, dephosphorization ratio, and phosphorus content of pellets were studied. The reaction process of fluorapatite in high-phosphorus iron ore was investigated. The results showed that when the metallization ratio of pellets reached maximum (95%), the dephosphorization ratio was only 5.6%, thus indicating adverse result. The reduction processes of high-phosphorus iron ore under vacuum and nitrogen environment were, respectively, compared under the optimal condition. It was found that the metallization ratio of pellets in the vacuum condition was higher than that under the nitrogen condition, while the dephosphorization ratio showed an opposite result. This indicated that in the process of vacuum reduction, fluorapatite not only reacted with carbon to form gaseous phosphide, but also with iron to form compounds containing the Fe–P bond. Therefore, a new mechanism of reduction of fluorapatite was proposed as follows: 2Ca5(PO4)3F + 12Fe + 9SiO2 + 15C = 9CaSiO3 + 6Fe2P + 15CO + CaF2.
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37

Fontaine, Laurent, Nelson Thiffault, David Paré, J. André Fortin, and Yves Piché. "Phosphate-solubilizing bacteria isolated from ectomycorrhizal mycelium ofPicea glaucaare highly efficient at fluorapatite weathering." Botany 94, no. 12 (December 2016): 1183–93. http://dx.doi.org/10.1139/cjb-2016-0089.

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Fluorapatite-solubilizing bacteria were isolated from the hyphosphere of the ectomycorrhizal (ECM) fungus Wilcoxina sp., a dominant species in the Picea glauca (Moench) Voss rhizosphere. Hundreds of strains isolated from the ascomycete Wilcoxina sp. could dissolve tricalcium phosphate, while only 27 of them could produce clarification halos on fluorapatite-amended solid medium. Most of the fluorapatite-solubilizing strains belonged to the Burkholderia genus. Scanning electron microscopy observations have shown that these efficient phosphate-solubilizing bacteria (PSB) were able to completely solubilize fluorapatite crystals within 22 h. The efficient PSB Burkholderia sp. strain 205 and Curtobacterium sp. strain 168 were tested for their ability to associate with a genetically distant fungal host while fulfilling their phosphate-solubilizing function. Burkholderia sp. strain 205 successfully associated with the basidiomycete Laccaria bicolor (Maire) P.D.Orton when hydroxyapatite was the only phosphorus source available to the fungus, while there was no bacterial development when Laccaria bicolor could access soluble phosphorus as well. Optical microscopic observation of Laccaria bicolor associated with Burkholderia sp. revealed extensive colonization of fungal hyphae by the bacterium. These results suggest an important role of bacteria – ECM fungi associations in white spruce phosphate nutrition.
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38

Regan, Sean, Marian Lupulescu, Michael Jercinovic, Jeffrey Chiarenzelli, Michael Williams, Jared Singer, and David Bailey. "Age and Origin of Monazite Symplectite in an Iron Oxide-Apatite Deposit in the Adirondack Mountains, New York, USA: Implications for Tracking Fluid Conditions." Minerals 9, no. 1 (January 21, 2019): 65. http://dx.doi.org/10.3390/min9010065.

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Monazite crystals, intergrown with allanite, fluorapatite, and quartz from the Cheever Mine iron oxide-apatite (IOA-type) deposit in Essex County, New York, USA, display rare symplectite textures. Electron probe wavelength-dispersive spectrometry (WDS) mapping and major and trace element characterization of these features reveal a natural experiment in fluid-mediated monazite recrystallization. Two types of monazite with symplectite intergrowths have been recognized (Type I and II). Both types of symplectite development are associated with a decrease in HREE, Si, Ca, Th, and Y, but an increase in both La and Ce in monazite. Electron microprobe Th-U-total Pb analysis of Type I monazite with suitable ThO2 concentrations yielded a weighted mean age of 980 ± 5.8 Ma (MSWD: 3.3), which is interpreted as the age of monazite formation and the onset of symplectite development. Both types of monazite formed during a series of reactions from fluorapatite, and possibly britholite, to produce the final assemblage of monazite, allanite, and fluorapatite. Monazite formation was likely a response to evolving fluid conditions, which favored monazite stability over fluorapatite at ca. 980 Ma, possibly a NaCl brine. A subsequent transition to a Ca-dominated fluid may have then promoted the consumption of monazite to produce another generation of allanite and fluorapatite. Our results indicate that recrystallized monazite formed during fluid-mediated processes that, over time, trended towards an increasingly pure end-member composition. Regionally, these data are consistent with a magmatic-origin followed by fluid-mediated remobilization of select phases at subsolidus conditions for the Adirondack IOA deposits.
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39

Sun, Yongsheng, Wentao Zhou, Yuexin Han, and Yanjun Li. "Effect of Different Additives on Reaction Characteristics of Fluorapatite During Coal-Based Reduction of Iron Ore." Metals 9, no. 9 (August 23, 2019): 923. http://dx.doi.org/10.3390/met9090923.

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In the coal-based reduction of high phosphorus oolitic hematite, it is particularly important to study the mechanism of phosphorus regulation during the formation of iron metals for the efficient development and utilization of iron ore. In this study, the thermodynamics of the coal-based reduction process of fluorapatite in different mineral systems, effect mechanism of the reduction degree, kinetics, mineral composition, and morphology of structural evolution samples were systematically investigated using FactSage software, single factor analysis, the isothermal method, X-ray diffraction (XRD), scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS). Thermodynamic analysis indicates that the effect of the SiO2–Fe2O3–C system on reducing the initial reduction temperature of fluorapatite was stronger than that of the Al2O3–Fe2O3–C system. The effect mechanism of the reduction degree demonstrates that increasing the dosage of silica, iron oxide, carbon, reduction time, and reduction temperature could promote the reduction reaction of fluorapatite under certain conditions. Dynamics analysis shows that the best kinetic mechanism functions of the SiO2–Fe2O3–C system and the Al2O3–Fe2O3–C system were A1/3 = 1/3(1 − α)[−ln(1 − α)]−2 and A1/2 = 1/2(1 − α)[−ln(1 − α)]−1, respectively. The activation energy and pre-exponential factor of the reduction kinetics equation in the system containing silica were significantly lower than that in the system containing alumina, which explained that the catalytic effect of silica on the reduction of calcium fluorophosphate was far greater than that of alumina. XRD and SEM/EDS analysis indicate that the solid–solid reaction of alumina, silica, iron, and fluorapatite occurred during the reduction process, while calcium aluminate, calcium silicate, and calcium oxide were formed at the contact point. Among them, iron could absorb P2 gas so that it played a greater role in promoting the reduction of fluorapatite. Increasing the reduction temperature and prolonging the reduction time were beneficial to the reduction of fluorapatite.
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40

Sarlin, Tuija H., Outi K. Priha, Mona E. Arnold, and Päivi Kinnunen. "Bioleaching of Phosphorus from Low Grade Ores and Concentrates with Acidophilic Iron- and Sulphur-Oxidizing Bacteria." Advanced Materials Research 825 (October 2013): 266–69. http://dx.doi.org/10.4028/www.scientific.net/amr.825.266.

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Bioleaching experiments of phosphorus from low grade fluorapatite ore containing 8.2% P2O5 and from fluorapatite concentrate containing 29.8% P2O5 were carried out in shake flasks. Elemental sulphur was supplemented as an energy source for acid generation. Mixed and pure acidophilic bacterial cultures consisting of iron-and/or sulphur-oxidizing bacteria Acidithiobacillus ferrooxidans, A. thiooxidans and Leptospirillum ferrooxidans were used in the experiments. These acidophiles are commonly used in bioleaching of sulphide minerals, but their application on phosphorus bioleaching has been limited. Phosphorus leaching was shown to be a pH-dependant phenomenon. Phosphorus leaching yields of up to 97% and 28% were obtained in 3 weeks for low grade fluorapatite ore and concentrate, respectively. These results indicate a potential for applying bioleaching for phosphorus extraction from low grade materials.
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41

Stanic, Vojislav, Borivoj Adnadjevic, Suzana Dimitrijevic, Slavko Dimovic, Miodrag Mitric, Bojana Zmejkovski, and Slavko Smiljanic. "Synthesis of fluorapatite nanopowders by a surfactant-assisted microwave method under isothermal conditions." Nuclear Technology and Radiation Protection 33, no. 2 (2018): 180–87. http://dx.doi.org/10.2298/ntrp1802180s.

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Fluorapatite nanopowders with different amounts of fluoride ions were prepared using the surfactant-assisted microwave method under isothermal conditions. Microwave irradiation was applied for the rapid formation of crystals. A micellar solution of polyoxyethylene (23) lauryl ether was used as a regulator of nucleation and crystal growth. Characterization studies from X-ray diffraction, field-emission scaning electron microscopy and Fourier-transform infrared spectra showed that crystals have an apatite structure and particles of all samples are nano size, with an average length of 50 nm and about 15-25 nm in diameter. Antimicrobial studies have demonstrated that synthesized fluorapatite nanopowders exhibit activity against tested pathogens: Escherichia coli, Staphylococcus aureus and Candida albicans. Activity increased with the amount of fluoride ions. The synthesized fluorapatite nanomaterials are promising as materials in environmental protection and medicine for orthopedics and dental restorations.
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42

Lutišanová, Gabriela, Martin Palou, Milan Mikula, and Jana Kozánková. "Characterisation of the surface structure and bioactivity of glass and glass ceramics using surface topography." Open Chemistry 10, no. 6 (December 1, 2012): 1890–98. http://dx.doi.org/10.2478/s11532-012-0111-5.

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AbstractThe present paper reports the results of the relationship between the surface topography, microstructure and the in vitro bioactivity of samples with and without fluorapatite content in simulated body fluid. Glasses and glass ceramics belonging to the Li2O-SiO2-CaO-P2O5-CaF2 system were prepared by using conventional melting technique following by heat treatment to obtain glass ceramics. This current study demonstrates the benefits of combining two microscopic methods for better investigation of the surface structure. The formation of apatite layer on the surface and the increase in surface roughness proved that the glasses and glass ceramics with bioactive fluorapatite content could satisfy to the requirements for biomaterial applications. The results also showed that the roughness of apatite layer formed after immersion in body fluid on the surface of glasses with fluorapatite was more pronounced than that of equivalent glass ceramic samples cured under the same conditions.
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43

Boink, A. B. T. J., J. Wemer, J. Meulenbelt, H. A. M. G. Vaessen, and D. J. de Wildt. "The Mechanism of Fluoride-Induced Hypocalcaemia." Human & Experimental Toxicology 13, no. 3 (March 1994): 149–55. http://dx.doi.org/10.1177/096032719401300302.

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1 Fluoride intoxication leads to sudden cardiac death which has been assumed to result from the accompanying severe hypocalcaemia. The aim of this study has been to investigate the suggestion that fluorapatite formation rather than CaF2 precipitation is responsible for this low calcium. 2 Measurements of free Ca2+ and F- ion concentrations in HEPES buffered solutions containing F-, Ca2+, and phosphate ions at different concentrations in the absence and presence of hydroxyapatite showed that the presence of hydroxyapatite enhanced the decrease of Ca2+ and F- concentration. 3 The ratio of Ca2+:F- clearance was 5:1 which is consistent with formation of fluorapatite. These results support the hypothesis that hydroxyapatite acts as a nucleation catalyst for fluorapatite formation and this process is responsible for the hypocalcaemia induced by fluoride intoxication. 4 The proposed mechanism explains also the metabolic acidosis which is frequently seen in cases of fluoride intoxication.
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44

Jokanović, Vukoman, Božana Čolović, Marija Sandić-Živković, Marijana Popović Bajić, and Slavoljub Živković. "Structural characteristics and mechanisms of fluorapatite mechanochemical synthesis." Stomatoloski glasnik Srbije 63, no. 2 (June 1, 2016): 74–84. http://dx.doi.org/10.1515/sdj-2016-0008.

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Abstract This paper analyzes mechanisms of fluorapatite mechanochemical synthesis and its structural characteristics. Several studies of Jokanovic et al. published in appropriate journals and the book “Nanomedicine, the biggest challenge of the 21st century” are the base for this article. Characteristics of obtained materials show numerous biological advantages associated with the specific structural design of material during the process of synthesis. X-ray diffraction (XRD) and infrared spectroscopy with Fourier transform (FTIR) were used for studying the processes of fluorapatite synthesis.
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45

Nordquist, William D., Hajima Okudera, Yutaka Kitamura, Kazunari Kimoto, Toshimitsu Okudera, and David J. Krutchkoff. "Part II: Crystalline Fluorapatite-Coated Hydroxyapatite Implant Material: A Dog Study With Histologic Comparison of Osteogenesis Seen With FA-Coated HA Grafting Material Versus HA Controls: Potential Bacteriostatic Effect of Fluoridated HA." Journal of Oral Implantology 37, no. 1 (February 1, 2011): 35–42. http://dx.doi.org/10.1563/aaid-joi-d-10-00164.

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Abstract Success of osteogenesis in bone graft procedures can be enhanced by inhibiting oral bacterial infections through the use of prophylactic bacteriostatic fluoride within the grafting environment. Ideally, the fluoride ion should be chemically sequestered and thus unavailable unless needed at times during the process of early infection. As fluoride within fluorapatite is tightly bound at neutral pH and becomes available only during acidic conditions, fluorapatite is an ideal store for the fluoride ion which becomes released for bacteriostasis only during an acidic environment found with incipient bacterial infection. The purpose of this investigation was to compare the histologic properties of new bone formed surrounding fluorapatite (FA)-coated microcrystalline hydroxyapatite (HA) grafting material with comparable bone formed following the use of control HA material (OsteoGen, Impladent, Ltd, Holliswood, NY). The results of histologic analysis within dog studies here showed no detectable difference in new bone following therapeutic grafting procedures using each of the above 2 mineral coatings.
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46

Wang, Hong You, Kang Ning Sun, Ting Shan, Xiu Qing Yang, Yan Zhao, and Yan Jie Liang. "Biomimetic Synthesis of Fluorapatite Coating." Advanced Materials Research 306-307 (August 2011): 63–71. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.63.

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In the present study, a simple method of regenerating microstructure of human tooth under near-physiological conditions (pH 7.0, 37 °C, 1 atm) was developed. Commercial gelatin was used as matrix materials in this method, which nucleated the formation of fluorapatite (FA) nanocrystals and regulated the growth of nanocrystals. As a result, the resulting thin FA coatings had been prepared on human tooth slices and sintered hydroxyapatite disks, which were in tight contact with the substrates. Besides, the morphologies of FA nanocrystals changed from acicular to hexagonal with the exchange cycle of gel increased. Electron dispersive spectrometer analysis indicated that some sodium and carbonate ions were incorporated into the FA crystal lattices and the calcium to phosphorus ratio was approximate 1.58. The mechanical properties of the resulting FA coating were investigated through nanoindentation system, which showed the similar hardness with dentin. In conclusion, this method demonstrated a potential application to repair tooth damage in dental clinics.
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47

Leroy, N., and E. Bres. "Structure and Substitutions in Fluorapatite." European Cells and Materials 2 (November 30, 2001): 36–48. http://dx.doi.org/10.22203/ecm.v002a05.

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48

Vance, E. R., Y. Zhang, T. McLeod, and M. Jovanovic. "Preparation of Pu-doped fluorapatite." Journal of Nuclear Materials 426, no. 1-3 (July 2012): 223–25. http://dx.doi.org/10.1016/j.jnucmat.2012.03.038.

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49

OISHI, Shuji, and Teruyuki KAMIYA. "Flux Growth of Fluorapatite Crystals." NIPPON KAGAKU KAISHI, no. 9 (1994): 800–804. http://dx.doi.org/10.1246/nikkashi.1994.800.

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50

Bogdanov, B. I., P. S. Pashev, J. H. Hristov, and I. G. Markovska. "Bioactive fluorapatite-containing glass ceramics." Ceramics International 35, no. 4 (May 2009): 1651–55. http://dx.doi.org/10.1016/j.ceramint.2008.07.021.

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