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Literatura académica sobre el tema "Crystals Apatite"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 4 de febrero de 2022

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Artículos de revistas sobre el tema "Crystals Apatite"

Ren, Fu Zeng y Yang Leng. "Carbonated Apatite, Type-A or Type-B?" Key Engineering Materials 493-494 (octubre de 2011): 293–97. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.293.

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Carbonated apatite, the basic mineral component in human hard tissues and an important bioceramic material, has been extensively studied. However, its atomic arrangements in apatite crystal structure and its experimental characterization are still not lack of debating. We analyzed infrared (IR) vibrational spectroscopy for carbonated apatite determinations, by comparatively studying the IR spectra of hydroxyapatite and of surface carbonate absorption, biological apatites (human enamel, human cortical bone, and two animal bones) and carbonated apatite. The carbonated apatite samples were sythesized by various methods, including precipitation method, hydrothermal reaction and solid-gas reaction at high temperature. The comparative study indicates that the bands at ~880 cm-1, ~1413 cm-1, and ~1450 cm-1 should not be used to identify carbonated apatite since they may result from carbonate absorption on surfaces of apatite crystals or separated carbonate phase present with apatite crystals. The IR characteristic bands of carbonate substitution in apatites should be: ν3 at ~1465 cm-1 for type-B (CO3 substituting for PO4) and ν3 band at ~1546 cm-1 for type A (CO3 substituting for OH). These signature IR bands are further confirmed by the ab initio simulations.

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Hong, S. I., K. H. Lee, M. E. Outslay y D. H. Kohn. "Ultrastructural analyses of nanoscale apatite biomimetically grown on organic template". Journal of Materials Research 23, n.º 2 (febrero de 2008): 478–85. http://dx.doi.org/10.1557/jmr.2008.0051.

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The ultrastructure of nanoscale apatite biomimetically formed on an organic template from a supersaturated mineralizing solution was studied to examine the morphological and crystalline arrangement of mineral apatites. Needle-shaped apatite crystal plates with a size distribution of ∼100 to ∼1000 nm and the long axis parallel to the c axis ([002]) were randomly distributed in the mineral films. Between these randomly distributed needle-shaped apatite crystals, amorphous phases and apatite crystals (∼20–40 nm) with the normal of the grains quasi-perpendicular to the c axis were observed. These observations suggest that the apatite film is an interwoven structure of amorphous phases and apatite crystals with various orientations. The mechanisms underlying the shape of the crystalline apatite plate and aggregated apatite nodules are discussed from an energy-barrier point of view. The plate or needle-shaped apatite is favored in single-crystalline form, whereas the granular nodules are favored in the polycrystalline apatite aggregate. The similarity in shape in both single-crystalline needle-shaped apatite and polycrystalline granular apatite over a wide range of sizes is explained by the principle of similitude, in which the growth and shape are determined by the forces acting upon the surface area and the volume.

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Shimoda, S., T. Aoba, E. C. Moreno y Y. Miake. "Effect of Solution Composition on Morphological and Structural Features of Carbonated Calcium Apatites". Journal of Dental Research 69, n.º 11 (noviembre de 1990): 1731–40. http://dx.doi.org/10.1177/00220345900690110501.

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The composition of enamel mineral corresponds to that of a calcium carbonato-apatite. For insight to be gained into the precipitation of carbonato-apatites having specific properties (crystal size, morphology, and carbonate incorporation into the crystal lattice), apatites were prepared at 80°C in aqueous systems having various CO3 concentrations and pH values of around 7.5 or 10.5 (± 0.5). The various preparations had a wide range (0.005 to 0.19) of CO3/Ca molar ratios that bracket the ratios found in porcine enamel mineral at various developmental stages. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction analyses showed that the calcium apatites precipitating at neutral pH incorporated the carbonate into both the hydroxyl and phosphate ion sites in their lattices (A,B-types), whereas the preparations made at the alkaline pH (high OH-CO32- competition) or in the presence of fluoride (F--CO32- competition) yielded only the B-type carbonato-apatite. It was also ascertained that the size and morphology of the carbonato-apatites, assessed by specific surface area determination and high-resolution electron microscopy, were highly dependent on the driving force for precipitation and the presence of regulators (CO 32- and F-) in solution. In neutral media, early precipitates were thin-ribbon in appearance, but grew into crystals having flattened-hexagonal cross-sections. In the presence of fluoride or in alkaline media, acicular apatite crystals, precipitated initially, grew into large rod-like carbonato-apatites having a symmetric-hexagonal cross-section. In both neutral and alkaline solutions, carbonate inhibited the growth of apatite crystals along their c axis, leading to the formation of bulkier crystals. The formation of carbonato-apatites at the neutral pH and their properties are consistent with observations made on enamel minerals formed in the early developmental stages.

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Ishikawa, K., E. D. Eanes y M. S. Tung. "The Effect of Supersaturation on Apatite Crystal Formation in Aqueous Solutions at Physiologic pH and Temperature". Journal of Dental Research 73, n.º 8 (agosto de 1994): 1462–69. http://dx.doi.org/10.1177/00220345940730081101.

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The importance of supersaturation in the dynamics of apatite precipitation from aqueous solutions is well-established. To determine whether this parameter has a comparable impact on the concomitant development of the textural properties of this phase, such as crystal size and shape, we investigated mineral accretion in synthetic solutions seeded with 0.67 g/L apatite over a range of supersaturations at pH 7.4 and 37°C. A dual specific-ion electrode-controlled titration method was used to maintain the seeded reactions under the following solution conditions: 1.0 to 1.8 mmol/L Ca2+, 0.67 to 1.2 mmol/L total phosphate (PO 4), Ca/PO4 (initial) = 1.5, 143 mmol/L KNO3, and 10 mmol/L HEPES. Samples were collected for chemical and textural analyses when the seed apatite was reduced by new accretions to 1/2,1/4,1/8,1/16, and 1/32 of the total solids in suspension. All new accretions were found to be apatitic. At the lowest supersaturation, accretion occurred primarily by growth of the seed crystals. However, at the highest supersaturation examined, the crystals at the end of the experiments were actually smaller, on average, than the original seeds, even though the total mass increased 32-fold. The results suggest that proliferation of new crystals supplanted growth of the seed crystals as supersaturation was increased. The results also suggest that differences in tissue fluid supersaturation may contribute to the large disparity in dimensions between dentin and enamel apatite crystals.

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PARK, JONGEE y ABDULLAH OZTURK. "BIOACTIVITY OF APATITE–WOLLASTONITE GLASS-CERAMICS PRODUCED BY MELTING CASTING". Surface Review and Letters 20, n.º 01 (febrero de 2013): 1350010. http://dx.doi.org/10.1142/s0218625x13500108.

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Glass-ceramics containing only apatite and wollastonite crystals were produced in the system MgO-CaO-SiO2-P2O5-F by the melt casting process. The bioactivity of the glass-ceramics was determined by immersing the glass-ceramics in a simulated body fluid (SBF) and by assessing the resulting apatite formation on the free surface after various immersion durations. A 12-μm-thick apatite layer formed on the surface of the glass-ceramic containing only apatite crystals after 20 days immersion in SBF. However, the thickness of the apatite layer formed on the surface of the glass-ceramic containing apatite and wollastonite crystals was 1 μm. Results have shown that the bioactivity of glass-ceramic depends strongly on the type of crystal(s) developed during the glass-ceramic process and their proportion in the glassy matrix.

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Shevchyk, A. O., I. G. Svidrak, N. T. Bilyk y I. V. Poberezhska. "Crystallomorphological and physical properties of apatite from carbonatites". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 23, n.º 95 (9 de abril de 2021): 25–32. http://dx.doi.org/10.32718/nvlvet-f9505.

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This paper presents the results of the study of x-ray luminescence of apatite from different genetic types of apatite species in order to study its geochemical characteristics and the possibility of using as a mineral indicator the conditions of ore formation and for search purposes. Apatite Ca2Ca3(F,Cl,OH)2[PO4]3 contains impurities Gd3+, Ce3+, Eu2+, Dy3+, Sm3+, Nd3+ as well as Mn2+ and others. Syngony is hexagonal. Crystals of prismatic habit; usually ending in dipyramide or basopinacoid. Sometimes forms tabular crystals. A hexagonal prism is often preserved. Color greenish, bluish-green; pinkish-purple, gray; often white, colorless or brown. Quite often translucent due to the presence of small internal cracks and inclusions; sometimes the inclusions are arranged oriented, preferably parallel to the main axis of the crystal. Brightly luminesces in cathode, x-ray and ultraviolet rays. The intensity and color of luminescence varies widely depending on the impurities. The presence of three crystal chemical positions in the structure of apatite – two cationic and one anionic makes it possible to be realized in the mineral by a wide heterovalent substitution. The distribution of isomorphic impurities between the crystal chemical positions will depend on the type of cation, its amount, as well as anionic substitutions in apatite. To determine the luminescence intensity values of the characteristic isomorphic impurities of apatite TR3+ (Gd3+, Ce3+, Eu2+, Dy3+, Sm3+, Nd3+) and Mn2+, the X-ray luminescence method was applied. Apatites of different genetic types of the Aldan, Baltic Shields, the Baikal region (Russia), the Sette-Daban Range, and the Maimech-Kotui Province (Yakutia) and the Ukrainian Shield were investigated. The obtained values of luminescence intensity of TR3+ and Mn2+ can be used to diagnose the genetic type of apatite species, the conditions of mineral formation, the type of their mineralization and for search purposes. On the basis of factor analysis, it can be concluded that the intensity of the luminescence centers of rare earth elements in the apatites of each complex depends on the relative age position of the mineral in the groups of successively formed rocks. Analysis of apatite carbonatites from different deposits showed minimal fluctuations in the ratios of radiation intensity of X-ray centers (Ce3+, Sm3+, Mn2+, Eu2+), which may indicate a close geochemical situation and, consequently, the only source of matter in the formation of carbonates. Analysis of apatite carbonatites from different fields showed minimal fluctuations in the radiation intensity ratios of the centers of X-ray luminescence (Ce3+, Sm3+, Mn2+, Eu2+), which, in my opinion, may indicate a close geochemical situation and, as a consequence, the substance or the result.

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Simmelink, J. W. y S. C. Abrigo. "Crystal Morphology and Decalcification Patterns Compared in Rat and Human Enamel and Synthetic Hydroxyapatite". Advances in Dental Research 3, n.º 2 (septiembre de 1989): 241–48. http://dx.doi.org/10.1177/08959374890030022501.

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The purpose of this investigation was to compare morphology and dissolution patterns by ultrastructural examination of rat and human enamel crystals as well as synthetic apatite crystals. Mature enamel crystals were of particular interest, since crystal maturation appears to be inhibited in amelogenesis imperfecta. Specimens were isolated from developing and mature rat incisor enamel. Rat enamel, mature human enamel, and synthetic apatite were thin-sectioned without decalcification and examined by transmission electron microscopy. Some sections were exposed to acid, and selected synthetic apatite sections were further treated for removal of embedding plastic, followed by vacuum-shadow-coating with carbon. Results showed that cross-sections of rat, human, and synthetic crystals had a distortion in the flattened hexagonal outline in regions where the growth of one crystal impinged on another. Crystal dissolution occurred preferentially along the c-axis, producing a central defect or hole in the crystals. Preliminary studies with weak acid on mature human enamel indicate that the relatively soluble crystal core is quickly dissolved, while the outer shell remains intact over a much longer period of time. In the mature rat and human enamel, this crystal hole formation had a consistent dimension of approximately 10-nm thickness. The crystal hole dimension was the same size as crystals that are formed during the early secretory phase in rat amelogenesis. Acid-treated synthetic apatite also showed dissolution of the crystal core along the c-axis, but dimensions of the hole were not consistent. Shadowed grids showed that the defective hole penetrated the entire section thickness. Mature human enamel showed a unique variation to acid at rod borders where larger, isohexagonal crystals were resistant to acid dissolution. It was concluded that (1) crystals of rat and human enamel show evidence of diphasic growth that may affect their dissolution properties, and (2) unique acid-resistant crystals in human enamel at rod borders may be a result of long oral exposure.

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Deng, Chun Lin, Ying Jun Wang, Yao Wu, Xin Long Wang, Xiao Feng Chen, Hua De Zheng, Ji Yong Chen y Xing Dong Zhang. "Apatite Formation on Porous HA/TCP in Animals’ Serums In Vitro". Key Engineering Materials 330-332 (febrero de 2007): 955–58. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.955.

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Porous HA/TCP bioceramics were immersed in pure dog serum to observe apatite formation. Deposited crystals were examined using SEM. Results showed that beamed sheet-like crystals formed on the surface of ceramics granules, and after postponement immersion time, crystals extended and became bigger. EDS and IR results suggested formed crystals were defect-calcium type carbonated hydroxyapatite. HRTEM photograph suggested formation process of new-formed crystals from non-crystal to crystal in serum. Directional organisms acted maybe as a template in process of crystals formation, so new crystals developed along certain direction.

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Rey, Christian, Christèle Combes, Christophe Drouet y Hocine Sfihi. "Chemical Diversity of Apatites". Advances in Science and Technology 49 (octubre de 2006): 27–36. http://dx.doi.org/10.4028/www.scientific.net/ast.49.27.

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Apatites can accommodate a large number of vacancies and afford multiple ionic substitutions determining their reactivity and biological properties. Unlike other biominerals they offer a unique adaptability to various biological functions. The diversity of apatites is essentially related to their structure and to their mode of formation. Special charge compensation mechanisms allow molecular insertions and ion substitutions and determine to some extent their solubility behaviour. Apatite formation at physiological pH involves a structured surface hydrated layer nourishing the development of apatite domains. This surface layer contains relatively mobile and exchangeable ions, and is mainly responsible for the surface properties of apatite crystals from a chemical (dissolution properties, ion exchange ability, ion insertions, molecule adsorption and insertions) and a physical (surface charge, interfacial energy) point of view. These characteristics are used by living organisms and can also be exploited in material science.

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Mészárosová, Noemi, Roman Skála, Šárka Matoušková, Petr Mikysek, Jakub Plášil y Ivana Císařová. "Hydrothermal-to-metasomatic overprint of the neovolcanic rocks evidenced by composite apatite crystals: a case study from the Maglovec Hill, Slanské vrchy Mountains, Slovakia". Geologica Carpathica 69, n.º 5 (1 de octubre de 2018): 439–52. http://dx.doi.org/10.1515/geoca-2018-0025.

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Abstract The apatite assemblage from Maglovec hill (Slanské vrchy Mountains near the city of Prešov) from fissures of hydrothermally altered neovolcanic rocks (andesites and related lithologies) was studied. The assemblage consists of two different morphological apatite types (apatite in cores of prismatic crystals and fibrous apatite mantling these cores). The assemblage was investigated by a multi-analytical approach to reveal its unique chemical composition and structure. Both types of apatite display zoning visible in back-scattered electron (BSE) images. Core apatite is relatively homogenous with porous rims appearing darker in the BSE images at the contact with fibrous apatite, and occasionally with darker regions along fractures. These parts are depleted in trace elements, mostly in LREE. Fibrous apatites display concentric and/or patchy zoning. Dark regions in fibrous apatite occasionally display a porous structure. In part of fibrous crystals, substitution of (CO3)2− for phosphorus is confirmed by Raman spectroscopy by the presence of a band at ~ 1071 cm−1. This method also confirmed the presence of OH in different populations in the structure of all apatite types. The three most important observed peaks are caused by vibrations of hydroxyls influenced by different adjacent anions: hydroxyl (band at ~ 3575 cm−1); fluorine (band at ~ 3535–3540 cm−1); chlorine (band at ~ 3494 cm−1). In REE-depleted parts of both apatite types, fine inclusions of monazite and rarely Th-rich silicate are observed. The acquired data suggest a hydrothermal origin of this assemblage and indicate a formation sequence of distinct apatite types. Moreover, minerals from the epidote group were identified, which have not been described from this locality before as well as vanadium-rich magnetites that form exsolution lamellae in ilmenite grains.

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Tesis sobre el tema "Crystals Apatite"

Rulis, Paul Michael Ching Wai-Yim. "Computational studies of bioceramic crystals & related materials". Diss., UMK access, 2005.

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Thesis (Ph. D.)--Dept. of Physics and School of Computing and Engineering. University of Missouri--Kansas City, 2005.
"A dissertation in physics and computer networking." Advisor: Wai-Yim Ching. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed March 12, 2007. Includes bibliographical references (leaves 256-267). Online version of the print edition.

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Kockan, Umit. "Prediction Of Hexagonal Lattice Parameters Of Stoichiometric And Non-stoichiometric Apatites By Artificial Neural Networks". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610311/index.pdf.

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Apatite group of minerals have been widely used in applications like detoxification of wastes, disposal of nuclear wastes and energy applications in addition to biomedical applications like bone repair, substitution, and coatings for metal implants due to its resemblance to the mineral part of the bone and teeth. X-ray diffraction patterns of bone are similar to mineral apatites such as hydroxyapatite and fluorapatite. Formation and physicochemical properties of apatites can be understood better by computer modeling. For this reason, lattice parameters of possible apatite compounds (A10(BO4)6C2), constituted by A: Na+, Ca2+, Ba2+, Cd2+, Pb2+, Sr2+, Mn2+, Zn2+, Eu2+, Nd3+, La3+, Y3+
B: As+5, Cr+5, P5+, V5+, Si+4
and C: F-, Cl-, OH-, Br-1 were predicted from their elemental ionic radii by artificial neural networks techniques. Using artificial neural network techniques, prediction models of lattice parameters a, c and hexagonal lattice volumes were developed. Various learning methods, neuron numbers and activation functions were used to predict lattice parameters of apatites. Best results were obtained with Bayesian regularization method with four neurons in the hidden layer with &lsquo
tansig&rsquo
activation function and one neuron in the output layer with &lsquo
purelin&rsquo
function. Accuracy of prediction was higher than 98% for the training dataset and average errors for outputs were less than 1% for dataset with multiple substitutions and different ionic charges at each site. Non-stoichiometric apatites were predicted with decreased accuracy. Formulas were derived by using ionic radii of apatites for lattice parameters a and c.

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Luo, Yun. "Crystal Chemistry of U and Th in Apatite". Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1272635731.

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Kelly, Sean R. "STRUCTURAL MECHANISMS OF (POLY)ANION SOLID SOLUTION IN SYNTHETIC OH-Cl BINARY APATITE AND NATURAL F-OH-Cl TERNARY APATITE". Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1480963439051542.

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Van, Hoose Ashley Elizabeth. "Apatite Crystal Populations of the 1991 Mount Pinatubo Eruption, Philippines: Implications for the Generation of High Sulfur Apatite in Silicic Melts". PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/123.

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On June 15, 1991, Mount Pinatubo, Philippines, ejected 20 million tonnes of sulfur dioxide into the atmosphere, significantly impacting global climate and stratospheric ozone. Recharging basaltic magma mixed into the 50 km³ dacitic magma reservoir 6 to 11 km beneath Mount Pinatubo, and triggered the 1991 eruption. The result of the magma mixing was a hybrid andesite with quenched basalt inclusions that erupted as a dome between June 7 and June 12. On June 15, approximately 5 km³ of anhydrite-bearing magma was erupted from the main phenocryst-rich, dacitic reservoir. This study will utilize this extraordinary framework of the 1991 Pinatubo eruption to investigate the systematics of sulfur uptake by apatite in order to further develop apatite as a monitor for magmatic sulfur. In the dacite and hybrid andesite, apatite occurs as individual phenocrysts (up to ~200 μm diameter) or included within anhydrite, hornblende, and plagioclase phenocrysts. In the basaltic magmatic inclusions, apatite is found as acicular microphenocrysts. Electron microprobe data collected on apatite yield low- (0.7 wt.% SO₃) apatites in all juvenile products, and show that two distinct populations of apatites exist: "silicic" apatites (hosted in dacite and andesite) and basalt apatites. Apatites crystallizing from silicic melt have predominantly low- to medium-sulfur contents, but high-sulfur apatites with as much as 1.2-1.7 wt.% SO₃ occur sporadically as inclusions in plagioclase, hornblende, Fe-Ti oxide, and anhydrite. These concentrations are much higher than what could be achieved through equilibrium crystal-melt partitioning at pre-eruption conditions (760±20°C, 220MPa, NNO+1.7, 77 ppm S in melt inclusions) and a partition coefficient of 13. Apatite in the basalt is always sulfur-rich with compositions forming a continuous array between 0.7 to 2.6 wt.% SO₃. The population of apatite that crystallized from silicic melt has elevated cerium, fluorine, and chlorine and lower magnesium concentrations (average dacite values in wt.%: 0.21 Ce₂O₃, 1.4 F, 1.1 Cl, & 0.14 MgO) relative to the population of apatite from the basalt (average basalt values in wt.%: 0.05 Ce₂O₃, 1.0 F, 0.78 Cl, & 0.22 MgO). LA-ICP-MS trace element data also show distinct apatite populations between silicic and basalt apatites. Silicic apatites have elevated REE concentrations (La avg. = 750 ppm), lower Sr (avg.= 594 ppm), and a pronounced negative Eu anomaly (avg. Eu/Eu* = 0.57) relative to basalt apatites (avg. values: 217 ppm La, 975 ppm Sr, and Eu/Eu* = 1.16). The correlation of EMP sulfur data and LA-ICP-MS trace element data show no difference between high-S and low-S silicic apatites. These compositional systematics rule out the possibility that sulfur-rich apatite from dacite are inherited from mafic magma. Sulfur element maps of apatites show no evidence of S-diffusion from anhydrite hosts. Areas of high-S concentrations show complicated patterns that suggest multiple periods of sulfur enrichment. High-S silicic apatites are likely the product of "fluid-enhanced crystallization" from early enrichment of a SO₂ rich fluid phase from the underplating basalt, which occurred prior to or at anhydrite saturation. This fluid phase is the only possible sufficient source of sulfur for generating high-S apatites in a cool, "wet", dacitic melt. The dynamics of apatite sulfur enrichment via "fluid-enhanced crystallization" is yet unclear and requires further experimental laboratory investigation.

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Borkiewicz, Olaf J. "Formation of Precursor Calcium Phosphate Phases During Crystal Growth of Apatite and Their Role on the Sequestration of Heavy Metals and Radionuclides". Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1292008822.

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Chappell, Joseph Caleb. "CHEMICAL AND STRUCTURAL CHARACTERIZATION OF FLUORAPATITE FROM THE POUDRETTE PEGMATITE, MONT SAINT-HILAIRE, QUEBEC, CANADA". Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1547221806721972.

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Viswanath, B. "Understanding The Growth And Properties Of Functional Inorganic Nanostructures : An Interfacial Approach". Thesis, 2008. http://hdl.handle.net/2005/785.

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Surfaces and interfaces are of fundamental importance from the nucleation to growth of crystals formed under different conditions such as vapor phase, liquid phase including biomineralisation conditions. Recently there is lot of interest in controlling the shape of nanoparticles during the synthesis due to their excellent shape dependent properties. Understanding the role of surfaces and interfaces is vital for such shapecontrolled synthesis of nanomaterials. On the surface, coordination number, structure, density and composition are different from that of bulk and hence the properties are completely different in the surfaces and interfaces of any crystalline material. Especially when the length scale become nanoscale, the surface and interface play a dominant important role and leads to several new and interesting phenomena. In this dissertation, the role of surfaces and interfaces on the synthesis and the properties of inorganic functional nanostructures have been studied. The work primarily relies on basic chemistry to synthesize nanostructures that brings the importance of surfaces/interfaces into the picture. Though several basic characterization techniques have been used, electron microscopy has been the emphasis and has been used extensively through the work to probe and explore the materials for characterizing the structures over a variety of length scales. The entire thesis based on the results and findings obtained from the present investigation are organized as follows: Chapter1 gives a general introduction to the surfaces and interfaces to create a background for the investigation. This emphasizes the role of surfaces and interfaces in several aspects starting from nucleation, growth to the properties of inorganic crystals. It gives some exposure in to the different type of surface phenomenon which is common in nanoscale materials. Chapter 2 deals with the materials and methods which essentially gives the information about the materials used for the synthesis and the techniques utilized to characterize the materials chosen for the investigation. Chapter 3 deals with predicting the morphology of 2D nanostructures by combining the crystal growth theory into chemical thermodynamics. Morphology diagrams have been developed for Au, Ag, Pt and Pd to predict conditions under which two-dimensional nanostructures form as a result of a chemical reaction. In addition, it provides the general understanding of shape control in 2D nanostructures with atomistic mechanism. The validity of the morphology diagram has been tested for various noble metals by carrying out critical experiments. As a result, 2D nanostructures of metals projecting the lowest energy facet resulted in a complete novel way in the absence of any capping/reducing agents. Chapter 4 deals with predicting the formation of 2D nanostructures of inorganic crystals formed as a result of precipitation reaction. Morphology diagram has been developed for the case of hydroxyapatite, an inorganic part of the human bone. This answers some of the long standing question related to the shape of the HA crystals formed in the bone by biomineralisation. The generality of the method has been tested to few other inorganic crystals such as CaCO3, ZnO and CuO formed through precipitation reaction. The key finding of the above two chapter is that the low driving force of the chemical reactions results in two dimensional nanostructures. On contrary, high chemical driving force combined with the optimum zeta potential results in porous aggregate of nanoparticles. Chapter 5 discusses the formation of porous clusters of metals and ceramics at specific conditions. The mechanism behind the formation of monodisperse aggregates are investigated based on the interaction energies of nanoparticles in aqueous medium. This chapter reveals the role of surface charge and the surface energy in controlling the stability of nanoparticles in aqueous medium. In addition, it provides the simple methodology to produce well controlled porous clusters by exploiting the competition between surface charge and surface energy during the aggregation. The application of the porous clusters of Pt has been tested for methanol oxidation which is essential for fuel cell applications. Chapter 6 deals with the development of porous biphasic scaffolds through the morphology transition of nanorods. Rod shape is not stable when subjected to high temperature due to instability and spherodisation takes place to minimize the surface energy. Here in this chapter, by exploiting spherodisation along with the phase transition, highly interconnected porous structure of hydroxyapatite and tricalcium phosphate is achieved. Combined with the morphology transition, by adding naphthalene as a template, the possibility of achieving hierarchical porous structure also presented. The mechanical strength of the biphasic porous scaffold has been tested by microindentation. Mechanical properties of apatite are generally poor and there are lots of efforts to improve the mechanical properties apatite by the composite approach. Chapter 7 deals with the HA-Alumina and HA-TCP composites. In spite of much attention given to the mechanical properties of the composites, the interfacial phenomenon that takes place between the components of the nanocomposite has not been studied in detail. In the present study, interfacial reactions in hydroxyapatite-alumina nanocomposites have been investigated and new reaction mechanism also proposed. The degradation of densification process has been observed for the HATCP composites due to the creation of porous interface between HA crystals and TCP matrix. Mechanical properties of these two composites have been studied using microindentation. The mechanical properties of HA and TCP single crystals are important for developing the biphasic composites with reliable mechanical properties. Chapter8deals with the mechanical behavior of hydroxyapatite and tricalcium phosphate single crystals. The mechanical properties of HA and TCP have been studied by performing nanoand microindentation on specific crystallographic facets. In case of hydroxyapatite, the anisotropy in mechanical properties has been explored by performing indentation on its prism and basal planes. Nanoscale plasticity is observed in both HA and TCP crystals which arise due to the easy movement of surface atoms with lesser coordination compared to the bulk. Nanoindentation has been performed in the calciumdeficient HA platelets provides important clues about the role of calcium deficiency on the mechanical behavior of bone and has implications for the properties of osteoporotic bones.

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Zheng-WeiChen y 陳正威. "Crystal Structure and Electrical Properties of La/Ge Based Apatite Ionic Conductors". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/xgnays.

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碩士
國立成功大學
資源工程學系
104
Apatite structures have the highest conductivity of all solid oxide fuel cell (SOFC) electrolytes because of their conduction mechanism. Among all apatite-type electrolytes, lanthanum germanates possess the highest conductivity. To observe the relationship between composition, crystal structure, and ionic conductivity, lanthanum germanates (La10-xGe6O27-1.5x, x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the solid-state method. The XRD pattern showed that a single phase could be obtained for all compositions calcined at 1200°C/3 h. Crystal structure analysis using the Rietveld refinement approach indicated that x = 0.5, 0.75, 1 has a hexagonal structure (P63/m, #176) and x = 0, 0.25 has a triclinic structure (Pī, #2). These results show that five migration pathways could be established, assuming the interstitial oxygen passes the larger opening within the crystal structure. These five migration pathways are sinusoid-like three-dimensional routes along the c-axis. Since x = 0, 0.25 transforms to a triclinic phase, the migration opening becomes narrower and lowers the ionic conductivity. The Arrhenius plot of x = 0.25 demonstrated a sharp decrease in activation energy, indicating that the phase transition from triclinic to hexagonal occurred at around 650°C.

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Yu-HsuanLin y 林鈺烜. "Crystal Structure and Ionic Conductivity of La9.5Ge6-xNixO26.25-x Electrolytes of Apatite Structure". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/71960743327093420609.

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碩士
國立成功大學
資源工程學系
103
Apatite materials based on lanthanum germanates and doped with nickel (La9.5Ge6−xNixO26.25−x, x = 0, 0.1, 0.15, 0.2, 0.25, 0.5, 0.75, 1) were prepared to synthesize a single phase through solid-state method. XRD patterns indicate that the second phase (LaNiO3) existed when x = 0.25. Accordingly, the limit of solid solubility (x) was approximately 0.25. A single phase could be obtained when the compositional range was 0 ≤ x ≤ 0.25. Crystal structure analysis refined through the Rietveld method distinctly showed that the sample when x = 0 has a hexagonal structure (P63/m). From this result, four possible migration pathways may be established if the interstitial oxygen passes through the largest region in the entire crystal structure. These four pathways are screwlike, three-dimensional routes around the c axis for nickel-doped samples, which have triclinic structure. Because of the complicated structure, migration of interstitial oxygen becomes very difficult. The relationship between the decrease in conductivity and the decrease in interstitial oxygens may be explained by Raman spectroscopy.

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Libros sobre el tema "Crystals Apatite"

(Editor), Robert L. Wortmann, H. Ralph Schumacher (Editor), Michael A. Becker (Editor) y Lawrence M. Ryan (Editor), eds. Crystal-Induced Arthropathies: Gout, Pseudogout and Apatite-Associated Syndromes. Informa Healthcare, 2006.

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McConnell, Duncan. Apatite: "Its Crystal Chemistry, Mineralogy, Utilization, and Geologic and Biologic Occurrences". Springer, 2012.

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Dai, Yongshan. X-ray crystallographic studies: Part I, Crystal structures and crystal chemistry of lead-bearing apatites in the vanadinite-pyromorphite-mimetite ternary system, and, Part II, A preliminary study on thermally-induced al-si disorder in the crystal structure of sillimanite. 1990.

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Capítulos de libros sobre el tema "Crystals Apatite"

Riese, R., J. Wiessner, J. Kleinman, G. Mandel y N. Mandel. "Binding of Calcium Oxalate and Apatite Crystals to Renal Papillary Collecting Tubule Cells in Primary Culture". En Urolithiasis, 75–78. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4899-0873-5_24.

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Zhou, Hong Hui, Hui Li y Ling Hong Guo. "Molecular and Crystal Structure Characterization of Calcium-Deficient Apatite". En Key Engineering Materials, 119–22. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-422-7.119.

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Elliott, J. C. "Structure, Crystal Chemistry and Density of Enamel Apatites". En Ciba Foundation Symposium 205 - Dental Enamel, 54–72. Chichester, UK: John Wiley & Sons, Ltd., 2007. http://dx.doi.org/10.1002/9780470515303.ch5.

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Suetsugu, Yasushi, Toshiyuki Ikoma, Masanori Kikuchi y Junzo Tanaka. "Single Crystal Growth and Structure Analysis of AB-Type Carbonate Apatite". En Advanced Biomaterials VI, 525–28. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-967-9.525.

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Hughes, John M. y John Rakovan. "1. The Crystal Structure of Apatite, Ca5(PO4)3(F,OH,Cl)". En Phosphates, editado por Matthew J. Kohn, John Rakovan y John M. Hughes, 1–12. Berlin, Boston: De Gruyter, 2002. http://dx.doi.org/10.1515/9781501509636-004.

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Taki, A., Hideyuki Yoshimura y Mamoru Aizawa. "Microstructural Observation of Calcium-Deficient Single Crystal Apatite Fibers and Phase Changes during Heating". En Bioceramics 20, 147–50. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-457-x.147.

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Sprio, Simone, Gian Carlo Celotti, Elena Landi y Anna Tampieri. "Activation of Hydroxyapatite Crystal Growth on the Surface of Biomimetic Synthetic Apatites through Electrical Polarization". En Bioceramics 17, 521–24. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-961-x.521.

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Roddy, Edward y Michael Doherty. "Crystal-related arthropathies". En Oxford Textbook of Medicine, editado por Richard A. Watts, 4482–94. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0451.

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Many crystals have been associated with arthropathies or periarticular syndromes: only monosodium urate (gout), calcium pyrophosphate (acute calcium pyrophosphate crystal arthritis, chondrocalcinosis), and basic calcium phosphates (mainly hydroxyapatite) are common. Crystals implicated in joint disease are stable, hard particles that exert biological effects via surface-active (activation of humoral and cell-derived mediators, interaction with cell membranes) and mechanical properties. In general, smaller particle size, marked surface irregularity, and high negative surface charge correlate with inflammatory potential. A ‘crystal deposition disease’ is defined as a pathological condition associated with mineral deposits that contribute directly to the pathology. This is probably the situation for all manifestations of gout, for acute syndromes associated with calcium pyrophosphate, and for acute apatite periarthritis.

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Monma, H., Y. Kitami y M. Tsutsumi. "Characterization of electrolytically prepared calcium-deficient apatite single crystals". En Advanced Materials '93, 781–84. Elsevier, 1994. http://dx.doi.org/10.1016/b978-0-444-81991-8.50190-4.

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Moore, Robert C., Jim Szecsody, Michael J. Truex, Katheryn B. Helean, Ranko Bontchev y Calvin Ainsworth. "Formation of Nanosized Apatite Crystals in Sediment for Containment and Stabilization of Contaminants". En Environmental Applications of Nanomaterials, 89–108. IMPERIAL COLLEGE PRESS, 2012. http://dx.doi.org/10.1142/9781848168053_0004.

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Actas de conferencias sobre el tema "Crystals Apatite"

KAWAGOE, D., K. IOKU, H. FUJIMORI y S. GOTO. "TRANSPARENT APATITE CERAMICS PREPARED FROM APATITE FINE CRYSTALS SYNTHESIZED HYDROTHERMALLY". En Proceedings of the Seventh International Symposium on Hydrothermal Reactions. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812705228_0015.

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DeLoach, L. D., S. A. Payne, W. F. Krupke, L. K. Smith, W. L. Kway, J. B. Tassano y B. H. T. Chai. "Laser and Spectroscopic Properties of Yb-Doped Apatite Crystals". En Advanced Solid State Lasers. Washington, D.C.: OSA, 1993. http://dx.doi.org/10.1364/assl.1993.lm3.

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Payne, Stephen A., Laura D. DeLoach, Larry K. Smith, William F. Krupke, Bruce H. T. Chai y George Loutts. "New Ytterbium-Doped Apatite Crystals for Flexible Laser Design". En Advanced Solid State Lasers. Washington, D.C.: OSA, 2004. http://dx.doi.org/10.1364/assl.1994.yl3.

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Deuerling, Justin M., Weimin Yue, Alejandro A. Espinoza y Ryan K. Roeder. "Specimen Specific Multiscale Model for the Anisotropic Elastic Properties of Human Cortical Bone Tissue". En ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-175240.

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The elastic constants of cortical bone are orthotropic or transversely isotropic depending on the anatomic origin of the tissue. Micromechanical models have been developed to predict anisotropic elastic properties from structural information. Many have utilized microstructural features such as osteons, cement lines and Haversian canals to model the tissue properties [1]. Others have utilized nanoscale features to model the mineralized collagen fibril [2]. Quantitative texture analysis using x-ray diffraction techniques has shown that elongated apatite crystals exhibit a preferred orientation in the longitudinal axis of the bone [3]. The orientation distribution of apatite crystals provides fundamental information influencing the anisotropy of the extracellular matrix (ECM) but has not been utilized in existing micromechanical models.

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Noginov, M. A., G. B. Loutts, C. E. Bonner, S. Taylor, S. Stefanos, R. M. Wynne, B. A. Lasley, A. M. Anderson y J. C. Wang. "Bridging the gap between Yb3+ emission and Nd3+ emission in apatite crystals". En Advanced Solid State Lasers. Washington, D.C.: OSA, 2001. http://dx.doi.org/10.1364/assl.1999.wb16.

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Noginov, Mikhail A., George B. Loutts, B. Lucas, D. Fider, Patrick T. Higgins, A. Truong, Natalia E. Noginova, Norman P. Barnes y Stefan Kueck. "Crystal growth and spectroscopic studies of Nd-doped apatite crystals as active media for 944.11-nm laser". En Symposium on High-Power Lasers and Applications, editado por Richard Scheps. SPIE, 2000. http://dx.doi.org/10.1117/12.382788.

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Bonich, Mariana B., Scott D. Samson, James R. Metcalf y Rebecca M. Flowers. "THERMOCHRONOLOGICAL AND ISOTOPIC CHARACTERIZATION OF SINGLE APATITE CRYSTALS: FROM MAGMA SOURCE TO EXHUMATION". En GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-284872.

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Chaikina, Marina. "Structural and phase transformation of apatite and quartz in the indentation process single crystals". En INTERNATIONAL CONFERENCE ON PHYSICAL MESOMECHANICS OF MULTILEVEL SYSTEMS 2014. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4898888.

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Tampieri, A., M. Sandri, T. D’Alessandro, M. Banobre-Lopez y J. Rivas. "Innovative Biomimetic Hybrid Composites to Repair Multifunctional Anatomical Region". En ASME 2010 5th Frontiers in Biomedical Devices Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/biomed2010-32059.

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The development of biomimetic materials for osteochondral tissue substitution and repair can be the start for a revolution in the classical procedures of orthopaedic surgery. The persisting problems, linked to the absence of a complete functional recovery of the articulation and to the stabilization and protraction of the half-life of an articular prosthesis can be overcome by the new class of osteochondral substitutes. The characteristics of the artificial bone tissue are drastically different from those of the natural one and this is mainly due to the absence of the peculiar self-organizing interaction between apatite crystals and proteic matrix. At this purpose a biomimetic approach was used in which apatitic phases are directly nucleated on different macromolecular matrices, which act as template and induce peculiar physico-chemical features in the mineral phase to create a substitute for osteochondral lesions. In particular a biologically inspired approach was applied to nucleate bone-like hydroxyapatite (HA) nanocrystals on self-assembling collagen fibers. Biohybrid composite materials were obtained mimicking composition, structure and morphology of human osteochondral interfaces. [1–4]

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Deymier-Black, Alix C., Andrea G. Schwartz, Zhonghou Cai, Guy M. Genin y Stavros Thomopoulos. "Mineral Morphology at the Tendon-to-Bone Interface Observed via High Energy X-Ray Diffraction". En ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14731.

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Tough, graded interfaces are a broadly conserved feature of biological attachment of two dissimilar materials, but the mechanisms by which toughening occurs are not fully known. In biological systems, graded structures are commonly found in the attachments of materials with very different properties such as bone, which is very stiff, and tendon, which is compliant 1. Previous research has shown that the interface between these two materials is composed mostly of collagen, proteoglycans, and carbonated apatite crystals (mineral). Our working hypothesis is that gradients in mineral content and collagen orientation combine to provide a compliant energy absorbing region between the tendon and bone 1.

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Informes sobre el tema "Crystals Apatite"

Payne, S. A., L. D. DeLoach, L. K. Smith, W. F. Krupke, B. H. T. Chai y G. Loutts. New ytterbium-doped apatite crystals for flexible laser design. Office of Scientific and Technical Information (OSTI), marzo de 1994. http://dx.doi.org/10.2172/10166773.

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Van Hoose, Ashley. Apatite Crystal Populations of the 1991 Mount Pinatubo Eruption, Philippines: Implications for the Generation of High Sulfur Apatite in Silicic Melts. Portland State University Library, enero de 2000. http://dx.doi.org/10.15760/etd.123.

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