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Sample records for apatite nulcleation crystal

  1. Apatite crystal in hard tissue of conodont fossils

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The present study was aimed at examining the nature of apatite crystal in the tooth apparatus of a conodont fossil using transmission electron microscopy (TEM),scanning electron microscopy (SEM),laser Raman microprobe spectrometry and electron-probe microanalysis (EPMA).The hard tissue of the condont consisted of 2 layers and the organization varied with the size of the crystal.Higher magnification showed that the crystals were observed in the lattice of (100) and the central dark lines were not present.Ca,P,and F were detected in the crystal using EPMA.Our results indicate that the apatite crystal in conodont fossils is not hydroxyapatite but fluorapatite.

  2. Crystal Chemistry of Carbonate Apatites from High-Pressure Synthesis

    Science.gov (United States)

    Fleet, M. E.; Liu, X.

    2007-12-01

    Relatively large (50-200 μm) crystals of carbonate-bearing hydroxylapatite (CHAP) and fluorapatite (CFAP) have been grown from carbonate-rich melts at 1-3 GPa and used to determine structural details beyond the resolution of Rietveld powder diffraction methods, using X-ray single-crystal structure and FTIR spectroscopy. The new information includes the structural location of the channel (type A) and phosphate group (type B) carbonate ions in various composition series, as well as the location of the excess fluoride anion in francolite, substitution mechanisms, and identification of the hydrogen carbonate (bicarbonate) ion as a new apatite channel species. For equivalent conditions of synthesis, the uptake of A-B carbonate is greater for Na-bearing CHAP (up to 2 carbonate ions pfu) than Na-bearing CFAP (about 0.4 pfu). The Na cation and A and B carbonate ions are locally coupled in ratios of 1:1:1 in CHAP and 1:1:2 in CFAP, to minimize the effects of charge compensation and spatial accommodation. An extensive data base of type A and B site occupancies reveals that the amount of A carbonate in type A-B CHAP and CFAP is considerably under represented by the relative band areas for asymmetric stretching (ν3) and out-of-plane bending (ν2) of carbonate in FTIR spectra. The weaker absorption intensity and shift to higher wavenumbers of type A bands indicates that the carbonate ion is bound more weakly in the apatite channel than in the interior of the crystal structure. Thus literature spectra for apatites, and especially for apatite biomineralisation, showing dominant amounts of B carbonate should be re-evaluated.

  3. Method for fabricating apatite crystals and ceramics

    Science.gov (United States)

    Soules, Thomas F.; Schaffers, Kathleen I.; Tassano, Jr., John B.; Hollingsworth, Joel P.

    2013-09-10

    The present invention provides a method of crystallizing Yb:C-FAP [Yb.sup.3+:Ca.sub.5(PO.sub.4).sub.3F], by dissolving the Yb:C-FAP in an acidic solution, following by neutralizing the solution. The present invention also provides a method of forming crystalline Yb:C-FAP by dissolving the component ingredients in an acidic solution, followed by forming a supersaturated solution.

  4. Incorporation of iodine into apatite structure: a crystal chemistry approach using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Jianwei eWang

    2015-06-01

    Full Text Available Materials with apatite crystal structure provide a great potential for incorporating the long-lived radioactive iodine isotope (129I in the form of iodide (I- from nuclear waste streams. Because of its durability and potentially high iodine content, the apatite waste form can reduce iodine release rate and minimize the waste volume. Crystal structure and composition of apatite was investigated for iodide incorporation into the channel of the structure using Artificial Neural Network. A total of 86 experimentally determined apatite crystal structures of different compositions were compiled from literature, and 46 of them were used to train the networks and 42 were used to test the performance of the trained networks. The results show that the performances of the networks are satisfactory for predictions of unit cell parameters a and c and channel size of the structure. The trained and tested networks were then used to predict unknown compositions of apatite that incorporates iodide. With a crystal chemistry consideration, chemical compositions that lead to matching the size of the structural channel to the size of iodide were then predicted to be able to incorporate iodide in the structural channel. The calculations suggest that combinations of A site cations of Ag+, K+, Sr2+, Pb2+, Ba2+, and Cs+, and X site cations, mostly formed tetrahedron, of Mn5+, As5+, Cr5+, V5+, Mo5+, Si4+, Ge4+, and Re7+ are possible apatite compositions that are able to incorporate iodide. The charge balance of different apatite compositions can be achieved by multiple substitutions at a single site or coupled substitutions at both A and X sites. The results give important clues for designing experiments to synthesize new apatite compositions and also provide a fundamental understanding how iodide is incorporated in the apatite structure. This understanding can provide important insights for apatite waste forms design by optimizing the chemical composition and synthesis

  5. Bioactive coatings on Portland cement substrates: Surface precipitation of apatite-like crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gallego, Daniel [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Higuita, Natalia [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Grupo de Investigacion en Ingenieria Biomedica CES-EIA (GIBEC), Carrera 43 A No. 52 Sur - 99, Sabaneta (Colombia); Garcia, Felipe [Grupo de Investigacion en Ingenieria Biomedica CES-EIA (GIBEC), Carrera 43 A No. 52 Sur - 99, Sabaneta (Colombia); Ferrell, Nicholas [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Hansford, Derek J. [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States)], E-mail: hansford.4@osu.edu

    2008-04-01

    We report a method for depositing bioactive coatings onto cement materials for bone tissue engineering applications. White Portland cement substrates were hydrated under a 20% CO{sub 2} atmosphere, allowing the formation of CaCO{sub 3}. The substrates were incubated in a calcium phosphate solution for 1, 3, and 6 days (CPI, CPII, and CPIII respectively) at 37 deg. C to induce the formation of carbonated apatite. Cement controls were prepared and hydrated with and without CO{sub 2} atmosphere (C+ and C- respectively). The presence of apatite-like crystals was verified by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The substrate cytocompatibility was evaluated via SEM after 24 hour cell cultures. SEM revealed the presence Ca(OH){sub 2} on C-, and CaCO{sub 3} on C+. Apatite-like crystals were detected only on CPIII, confirmed by phosphorus EDS peaks only for CPIII. Cells attached and proliferated similarly well on all the substrates except C-. These results prove the feasibility of obtaining biocompatible and bioactive coatings on Portland cement for bone tissue engineering applications.

  6. Shear-mediated crystallization from amorphous calcium phosphate to bone apatite.

    Science.gov (United States)

    Niu, Xufeng; Wang, Liyang; Tian, Feng; Wang, Lizhen; Li, Ping; Feng, Qingling; Fan, Yubo

    2016-02-01

    The contribution of fluid shear stress (FSS) on the conversion of amorphous calcium phosphate (ACP) to bone apatite is investigated. The ACP precursors are prepared by using a wet-chemistry method and further exposed to the constant FSS environment with values of 0.5, 1.0, 1.5, and 2.0Pa. At the designated time points, the apatites are characterized by transmission electron microscopy, X-ray diffraction, and inductively coupled plasma-mass spectroscopy. The results show that, the low FSS (≤1.0Pa) has positive effects on the transition of ACP, characterized by the accelerated crystallization velocity and the well-organized calcium-deficient hydroxyapatite (CDHA) structure, whereas the high FSS (>1.0Pa) has negative effects on this conversion process, characterized by the poor CDHA crystal morphologies and the destroyed structures. The bioactivity evaluations further reveal that, compared with the FSS-free group, the CDHA prepared under 1.0Pa FSS for 9h presents the more biocompatible features with pre-osteoblast cells. These results are helpful for understanding the mechanism of apatite deposition in natural bone tissue.

  7. Atomistic modelling study of lanthanide incorporation in the crystal lattice of an apatite

    International Nuclear Information System (INIS)

    Studies of natural and synthetic apatites allow to propose such crystals as matrix for nuclear waste storage. The neodymium substituted britholite, Ca9Nd(PO4)5(SiO4)F2. is a model for the trivalent actinide storage Neodymium can be substituted in two types of sites. The aim of this thesis is to compare the chemical nature of this two sites in fluoro-apatite Ca9(PO4)6F2 and then in britholite, using ab initio atomistic modeling. Two approaches are used: one considers the infinite crystals and the second considers clusters. The calculations of the electronic structure for both were performed using Kohn and Sham density functional theory in the local approximation. For solids, pseudopotentials were used, and wave functions are expanded in plane waves. For clusters, a frozen core approximation was used, and the wave functions are expanded in a linear combination of Slater type atomic orbitals. The pseudopotential is semi-relativistic for neodymium, and the Hamiltonian is scalar relativistic for the clusters. The validation of the solid approach is performed using two test cases: YPO4 and ScPO4. Two numerical tools were developed to compute electronic deformation density map, and calculate partial density of stases. A full optimisation of the lattice parameters with a relaxation of the atomic coordinates leads to correct structural and thermodynamic properties for the fluoro-apatite, compared to experience. The electronic deformation density maps do not show any significant differences. between the two calcium sites. but Mulliken analysis on the solid and on the clusters point out the more ionic behavior of the calcium in site 2. A neodymium substituted britholite is then studied. Neodymium location only induces local modifications in; the crystalline structure and few changes in the formation enthalpy. The electronic study points out an increase of the covalent character the bonding involving neodymium compared with the one related to calcium, particularly in the Nd

  8. Surface Structure Study of Crystal Hydroxy-Apatite from Fluorosis Enamels

    Directory of Open Access Journals (Sweden)

    Abdillah Imron Nasution

    2013-07-01

    Full Text Available Fluorosis is a condition due to ingestion of excessive amounts of fluor which can cause the change in tooth structure and strength. However, there is still lack of explanation on the surface structure of crystal hydroxyapatite that influences the microscopic characteristic of fluorosis enamel. Objectives: To investigate the surface structure of crystal hydroxy-apatite in fluorosis enamel. Materials and Methods: Determination of fluor concentration and the surface structure of normal and fluorosis enamel specimen were carried out by using Scanning Electron Microscopy/Energy Disperse X-Ray (SEM/EDX. Results: Fluor concentration of fluorosis enamel was significantly higher with increased surface roughness and porosity than normal enamel. SEM observation also showed gaps areas between enamel rods and visible aprismatic zone in some regions. Conclusion: High level of fluor concentration on fluorosis enamel indicated the subtitution of OH- by F- increasing the surface roughness of enamel surface.DOI: 10.14693/jdi.v16i3.100

  9. Apatite- and monazite-bearing glass-crystal composites for the immobilization of low-level nuclear and hazardous wastes

    Energy Technology Data Exchange (ETDEWEB)

    Wronkiewicz, D.J.; Wolf, S.F.; DiSanto, T.S.

    1995-12-31

    This study demonstrates that glass-crystal composite waste forms can be produced from waste streams containing high proportions of phosphorus, transition metals, and/or halides. The crystalline phases produced in crucible-scale melts include apatite, monazite, spinels, and a Zr-Si-Fe-Ti phase. These phases readily incorporated radionuclide and toxic metals into their crystal structures, while corrosion tests have demonstrated that glass-crystal composites can be up to 300-fold more durable than simulated high-level nuclear waste glasses, such as SRL 202U.

  10. Apatite- and monazite-bearing glass-crystal composites for the immobilization of low-level nuclear and hazardous wastes

    International Nuclear Information System (INIS)

    This study demonstrates that glass-crystal composite waste forms can be produced from waste streams containing high proportions of phosphorus, transition metals, and/or halides. The crystalline phases produced in crucible-scale melts include apatite, monazite, spinels, and a Zr-Si-Fe-Ti phase. These phases readily incorporated radionuclide and toxic metals into their crystal structures, while corrosion tests have demonstrated that glass-crystal composites can be up to 300-fold more durable than simulated high-level nuclear waste glasses, such as SRL 202U

  11. Synthesis and ultrastructure of plate-like apatite single crystals as a model for tooth enamel

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Zhi, E-mail: zhuang@meiji.ac.jp [Department of Applied Chemistry, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Yoshimura, Hideyuki, E-mail: hyoshi@isc.meiji.ac.jp [Department of Physics, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Aizawa, Mamoru, E-mail: mamorua@isc.meiji.ac.jp [Department of Applied Chemistry, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan)

    2013-07-01

    Hydroxyapatite (HAp) is an inorganic constituent compound of human bones and teeth, with superior biocompatibility and bioactivity characteristics. Its crystal structure is hexagonal, characterized by a(b)- and c-planes. In vertebrate long bones, HAp crystals have a c-axis orientation, while in tooth enamel, they have an a(b)-axis orientation. Many methods can be used to synthesize c-axis oriented HAp single crystals; however, to the best of our knowledge, there have been no reports on a synthesis method for a(b)-axis oriented HAp single crystals. In this study, we successfully synthesized plate-like HAp crystals at the air–liquid interface of a starting solution via an enzyme reaction of urea with urease. Crystal phase analysis and ultrastructure observations were carried out, and the results indicated that the particles were single crystals, with almost the same a(b)-axis orientation as tooth enamel. It is hoped that by utilizing their unique surface charge and atomic arrangement, the resulting particles can be used as a high-performance biomaterial, capable of adsorbing bio-related substances and a model for tooth enamel. - Highlights: ► Synthesis of plate-like hydroxyapatite crystals at air–liquid interface ► Ultrastructural analysis of plate-like hydroxyapatite crystals ► Plate-like hydroxyapatite single crystals with a high a(b)-axis orientation ► Plate-like hydroxyapatite single crystals as a model for tooth enamel.

  12. Matrix metalloproteinase-20 mediates dental enamel biomineralization by preventing protein occlusion inside apatite crystals.

    Science.gov (United States)

    Prajapati, Saumya; Tao, Jinhui; Ruan, Qichao; De Yoreo, James J; Moradian-Oldak, Janet

    2016-01-01

    Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin. We hypothesized that the absence of MMP-20 during amelogenesis results in the occlusion of amelogenin in the enamel hydroxyapatite crystals. We used spectroscopy and electron microscopy techniques to qualitatively and quantitatively analyze occluded proteins within the isolated enamel crystals from MMP-20 null and Wild type (WT) mice. Our results showed that the isolated enamel crystals of MMP-20 null mice had more organic macromolecules occluded inside them than enamel crystals from the WT. The crystal lattice arrangements of MMP-20 null enamel crystals analyzed by High Resolution Transmission Electron Microscopy (HRTEM) were found to be significantly different from those of the WT. Raman studies indicated that the crystallinity of the MMP-20 null enamel crystals was lower than that of the WT. In conclusion, we present a novel functional mechanism of MMP-20, specifically prevention of unwanted organic material entrapped in the forming enamel crystals, which occurs as the result of precise amelogenin cleavage. MMP-20 action guides the growth morphology of the forming hydroxyapatite crystals and enhances their crystallinity. Elucidating such molecular mechanisms can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair.

  13. Matrix metalloproteinase-20 mediates dental enamel biomineralization by preventing protein occlusion inside apatite crystals.

    Science.gov (United States)

    Prajapati, Saumya; Tao, Jinhui; Ruan, Qichao; De Yoreo, James J; Moradian-Oldak, Janet

    2016-01-01

    Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin. We hypothesized that the absence of MMP-20 during amelogenesis results in the occlusion of amelogenin in the enamel hydroxyapatite crystals. We used spectroscopy and electron microscopy techniques to qualitatively and quantitatively analyze occluded proteins within the isolated enamel crystals from MMP-20 null and Wild type (WT) mice. Our results showed that the isolated enamel crystals of MMP-20 null mice had more organic macromolecules occluded inside them than enamel crystals from the WT. The crystal lattice arrangements of MMP-20 null enamel crystals analyzed by High Resolution Transmission Electron Microscopy (HRTEM) were found to be significantly different from those of the WT. Raman studies indicated that the crystallinity of the MMP-20 null enamel crystals was lower than that of the WT. In conclusion, we present a novel functional mechanism of MMP-20, specifically prevention of unwanted organic material entrapped in the forming enamel crystals, which occurs as the result of precise amelogenin cleavage. MMP-20 action guides the growth morphology of the forming hydroxyapatite crystals and enhances their crystallinity. Elucidating such molecular mechanisms can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair. PMID:26513418

  14. Atomistic modelling study of lanthanide incorporation in the crystal lattice of an apatite; Etude par modelisation atomistique de l'incorporation de lanthanides dans le reseau cristallin d'une apatite phosphocalcique

    Energy Technology Data Exchange (ETDEWEB)

    Louis-Achille, V

    1999-07-01

    Studies of natural and synthetic apatites allow to propose such crystals as matrix for nuclear waste storage. The neodymium substituted britholite, Ca{sub 9}Nd(PO{sub 4}){sub 5}(SiO{sub 4})F{sub 2}. is a model for the trivalent actinide storage Neodymium can be substituted in two types of sites. The aim of this thesis is to compare the chemical nature of this two sites in fluoro-apatite Ca{sub 9}(PO{sub 4}){sub 6}F{sub 2} and then in britholite, using ab initio atomistic modeling. Two approaches are used: one considers the infinite crystals and the second considers clusters. The calculations of the electronic structure for both were performed using Kohn and Sham density functional theory in the local approximation. For solids, pseudopotentials were used, and wave functions are expanded in plane waves. For clusters, a frozen core approximation was used, and the wave functions are expanded in a linear combination of Slater type atomic orbitals. The pseudopotential is semi-relativistic for neodymium, and the Hamiltonian is scalar relativistic for the clusters. The validation of the solid approach is performed using two test cases: YPO{sub 4} and ScPO{sub 4}. Two numerical tools were developed to compute electronic deformation density map, and calculate partial density of stases. A full optimisation of the lattice parameters with a relaxation of the atomic coordinates leads to correct structural and thermodynamic properties for the fluoro-apatite, compared to experience. The electronic deformation density maps do not show any significant differences. between the two calcium sites. but Mulliken analysis on the solid and on the clusters point out the more ionic behavior of the calcium in site 2. A neodymium substituted britholite is then studied. Neodymium location only induces local modifications in; the crystalline structure and few changes in the formation enthalpy. The electronic study points out an increase of the covalent character the bonding involving neodymium

  15. Nucleation of apatite crystals in vitro by self-assembled dentin matrix protein 1

    Science.gov (United States)

    He, Gen; Dahl, Tom; Veis, Arthur; George, Anne

    2003-08-01

    Bones and teeth are biocomposites that require controlled mineral deposition during their self-assembly to form tissues with unique mechanical properties. Acidic extracellular matrix proteins play a pivotal role during biomineral formation. However, the mechanisms of protein-mediated mineral initiation are far from understood. Here we report that dentin matrix protein 1 (DMP1), an acidic protein, can nucleate the formation of hydroxyapatite in vitro in a multistep process that begins by DMP1 binding calcium ions and initiating mineral deposition. The nucleated amorphous calcium phosphate precipitates ripen and nanocrystals form. Subsequently, these expand and coalesce into microscale crystals elongated in the c-axis direction. Characterization of the functional domains in DMP1 demonstrated that intermolecular assembly of acidic clusters into a β-sheet template was essential for the observed mineral nucleation. Protein-mediated initiation of nanocrystals, as discussed here, might provide a new methodology for constructing nanoscale composites by self-assembly of polypeptides with tailor-made peptide sequences.

  16. Polysomatic apatites

    Energy Technology Data Exchange (ETDEWEB)

    Baikie, Tom; Pramana, Stevin S.; Huang, Yizhong; Ahmad, Zahara [Nanyang Technological Univ., Singapore (Singapore). Div. of Materials Science and Engineering; Ferraris, Cristiano [Museum National d' Histoire Naturelle, UMR-CNRS, 75 - Paris (France). Lab. de Mineralogie et Cosmochimie; Kendrick, Emma [Surrey Univ., Guildford (United Kingdom). Chemical Sciences; Knight, Kevin S. [Appleton Lab., Chilton, Didcot (United Kingdom). ISIS User Office; White, T.J. [Nanyang Technological Univ., Singapore (Singapore). Div. of Materials Science and Engineering; Australian National Univ., Canberra, ACT (Australia). Centre for Advanced Microscopy

    2010-02-15

    Certain complex structures are logically regarded as intergrowths of chemically or topologically discrete modules.When the proportions of these components vary systematically a polysomatic series is created, whose construction provides a basis for understanding defects, symmetry alternation and trends in physical properties. Here, we describe the polysomatic family A{sub 5N}B{sub 3N}O{sub 9N+6}X{sub N{delta}} (2{<=}N{<=}{infinity}) that is built by condensing N apatite modules (A{sub 5}B{sub 3}O{sub 18}X{sub {delta}}) in configurations to create B{sub n}O{sub 3n+1} (1{<=}n{<=}{infinity}) tetrahedral chains. Hydroxyapatite [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}] typifies a widely studied polysome where N=2 and the tetrahedra are isolated in A{sub 10}(BO{sub 4}){sub 6}X{sub 2} compounds, but N=3 A{sub 15}(B{sub 2}O{sub 7}){sub 3}(BO{sub 4}){sub 3}X{sub 3} (ganomalite) and N=4 A{sub 20}(B{sub 2}O{sub 7}){sub 6}X{sub 4} (nasonite) are also known, with the X site untenanted or partially occupied as required for charge balance. The apatite modules, while topologically identical, are often compositionally or symmetrically distinct, and an infinite number of polysomes is feasible, generally with the restriction being that an A:B = 5:3 cation ratio be maintained. The end-members are the N=2 polysome with all tetrahedra separated, and N={infinity}, in which the hypothetical compound A{sub 5}B{sub 3}O{sub 9}X contains infinite, cornerconnected tetrahedral strings. The principal characteristics of a polysome are summarized using the nomenclature apatite- (A B X)-NS, where A/B/X are the most abundant species in these sites, N is the number of modules in the crystallographic repeat, and S is the symmetry symbol (usually H, T, M or A). This article examines the state-of-the-art in polysomatic apatite synthesis and crystallochemical design. It also presents X-ray and neutron powder diffraction investigations for several polysome chemical series and examines the prevalence of

  17. Crystallization of Apatites

    DEFF Research Database (Denmark)

    Ibsen, Casper Jon Steenberg

    2014-01-01

    Biologien har altid været en kilde til inspiration for menneskeheden i jagten på nye og forbedrede materialer. En af grundende er, at naturen er god til at bygge stærke og specialiserede materialer ud fra simple udgangsstoffer. Mange af disse materialer er såkaldte kompositmaterialer, dvs. at de ...

  18. Bio-inspired citrate-functionalized apatite thin films crystallized on Ti-6Al-4V implants pre-coated with corrosion resistant layers.

    Science.gov (United States)

    Delgado-López, José Manuel; Iafisco, Michele; Rodríguez-Ruiz, Isaac; Gómez-Morales, Jaime

    2013-10-01

    In this paper the crystallization of a bioinspired citrate-functionalized apatite (cit-Ap) thin film (thickness about 2μm) on Ti-6Al-4V supports pre-coated with bioactive and corrosion resistant buffer layer of silicon nitride (Si3N4), silicon carbide (SiC) or titanium nitride (TiN) is reported. The apatitic coatings were produced by a new coating technique based on the induction heating of the implants immersed in a flowing calcium-citrate-phosphate solution at pH11. The influence of the buffer layers and the surface roughness of the substrate on the chemical-physical features and adhesion of the cit-Ap films were investigated. The best plasticity, compactness and adherence properties have been found in the Ap layer grown on Si3N4, followed by the Ap grown on SiC and TiN, respectively. The adhesion property was likely related to the roughness of the buffered substrates, whereas the compactness and plasticity were closely related to the operating conditions during the Ap crystallization (flow rate of the solution and increase of temperature) rather than to the nature of the buffer layer.

  19. Apatite-Melt Partitioning at 1 Bar: An Assessment of Apatite-Melt Exchange Equilibria Resulting from Non-Ideal Mixing of F and Cl in Apatite

    Science.gov (United States)

    McCubbin, F. M.; Ustunisik, G.; Vander Kaaden, K. E.

    2016-01-01

    The mineral apatite [Ca5(PO4)3(F,Cl,OH)] is present in a wide range of planetary materials. Due to the presence of volatiles within its crystal structure (X-site), many recent studies have attempted to use apatite to constrain the volatile contents of planetary magmas and mantle sources. In order to use the volatile contents of apatite to precisely determine the abundances of volatiles in coexisting silicate melt or fluids, thermodynamic models for the apatite solid solution and for the apatite components in multi-component silicate melts and fluids are required. Although some thermodynamic models for apatite have been developed, they are incomplete. Furthermore, no mixing model is available for all of the apatite components in silicate melts or fluids, especially for F and Cl components. Several experimental studies have investigated the apatite-melt and apatite-fluid partitioning behavior of F, Cl, and OH in terrestrial and planetary systems, which have determined that apatite-melt partitioning of volatiles are best described as exchange equilibria similar to Fe-Mg partitioning between olivine and silicate melt. However, McCubbin et al. recently reported that the exchange coefficients may vary in portions of apatite compositional space where F, Cl, and OH do not mix ideally in apatite. In particular, solution calorimetry data of apatite compositions along the F-Cl join exhibit substantial excess enthalpies of mixing. In the present study, we conducted apatite-melt partitioning experiments in evacuated, sealed silica-glass tubes at approximately 1 bar and 950-1050 degrees Centigrade on a synthetic Martian basalt composition equivalent to the basaltic shergottite Queen Alexandria Range (QUE) 94201. These experiments were conducted dry, at low pressure, to assess the effects of temperature and apatite composition on the partitioning behavior of F and Cl between apatite and basaltic melt along the F-Cl apatite binary join, where there is non-ideal mixing of F and Cl

  20. Apatite (U-Th-Sm)/He age dispersion arising from analysis of variable grain sizes and broken crystals - examples from the Scottish Southern Uplands

    Science.gov (United States)

    Łuszczak, Katarzyna; Persano, Cristina; Stuart, Finlay; Brown, Roderick

    2016-04-01

    Apatite (U-Th-Sm)/He (AHe) thermochronometry is a powerful technique for deciphering denudation of the uppermost crust. However, the age dispersion of single grains from the same rock is typical, and this hampers establishing accurate thermal histories when low grain numbers are analysed. Dispersion arising from the analysis of broken crystal fragments[1] has been proposed as an important cause of age dispersion, along with grain size and radiation damage. A new tool, Helfrag[2], allows constraints to be placed on the low temperature history derived from the analysis of apatite crystal fragments. However, the age dispersion model has not been fully tested on natural samples yet. We have performed AHe analysis of multiple (n = 20-25) grains from four rock samples from the Scottish Southern Uplands, which were subjected to the same exhumation episodes, although, the amount of exhumation varied between the localities. This is evident from the range of AFT ages (˜60 to ˜200 Ma) and variable thermal histories showing either strong, moderate and no support for a rapid cooling event at ˜60 Ma. Different apatite size and fragment geometry were analysed in order to maximise age dispersion. In general, the age dispersion increases with increasing AFT age (from 47% to 127%), consistent with the prediction from the fragmentation model. Thermal histories obtained using Helfrag were compared with those obtained by standard codes based on the spherical approximation. In one case, the Helfrag model was capable of resolving the higher complexity of the thermal history of the rock, constraining several heating/cooling events that are not predicted by the standard models, but are in good agreement with the regional geology. In other cases, the thermal histories are similar for both Helfrag and standard models and the age predictions for the Helfrag are only slightly better than for standard model, implying that the grain size has the dominant role in generating the age dispersion

  1. Crystal structure of apatite type Ca2.49Nd7.51(SiO4)6O1.75.

    Science.gov (United States)

    Le, Thu Hoai; Brooks, Neil R; Binnemans, Koen; Blanpain, Bart; Guo, Muxing; Van Meervelt, Luc

    2016-02-01

    The title compound, Ca2+x Nd8-x (SiO4)6O2-0.5x (x = 0.49), was synthesized at 1873 K and rapidly quenched to room temperature. Its structure has been determined using single-crystal X-ray diffraction and compared with results reported using neutron and X-ray powder diffraction from samples prepared by slow cooling. The single-crystal structure from room temperature data was found to belong to the space group P63/m and has the composition Ca2.49Nd7.51(SiO4)6O1.75 [dicalcium octa-neodymium hexa-kis-(ortho-silicate) dioxide], being isotypic with natural apatite and the previously reported Ca2Nd8(SiO4)6O2 and Ca2.2Nd7.8(SiO4)6O1.9. The solubility limit of calcium in the equilibrium state at 1873 K was found to occur at a composition of Ca2+x Nd8-x (SiO4)6O2-0.5x , where x = 0.49. PMID:26958389

  2. Crystal structure of apatite type Ca2.49Nd7.51(SiO46O1.75

    Directory of Open Access Journals (Sweden)

    Thu Hoai Le

    2016-02-01

    Full Text Available The title compound, Ca2+xNd8–x(SiO46O2–0.5x (x = 0.49, was synthesized at 1873 K and rapidly quenched to room temperature. Its structure has been determined using single-crystal X-ray diffraction and compared with results reported using neutron and X-ray powder diffraction from samples prepared by slow cooling. The single-crystal structure from room temperature data was found to belong to the space group P63/m and has the composition Ca2.49Nd7.51(SiO46O1.75 [dicalcium octaneodymium hexakis(orthosilicate dioxide], being isotypic with natural apatite and the previously reported Ca2Nd8(SiO46O2 and Ca2.2Nd7.8(SiO46O1.9. The solubility limit of calcium in the equilibrium state at 1873 K was found to occur at a composition of Ca2+xNd8–x(SiO46O2–0.5x, where x = 0.49.

  3. Sulfur evolution of the 1991 Pinatubo magmas based on apatite

    Science.gov (United States)

    Van Hoose, Ashley E.; Streck, Martin J.; Pallister, John S.; Wälle, Markus

    2013-05-01

    Using electron microprobe (EMP) and laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to collect major and rare-earth elements (REE), respectively, from apatites from the 1991 Mt. Pinatubo juvenile eruption products, we have determined that two statistically distinct populations of apatite exist. One population crystallized from the juvenile basaltic melt (basalt apatites) and the other population crystallized from the main dacitic magma body (silicic apatites). Both populations contain high-S apatites (> 0.7 wt.% SO3). Apatite has previously been shown to be a potential monitor for magmatic sulfur contents via numerous proposed coupled substitutions of P5 + for S6 +. However, simple apatite/melt partitioning cannot account for high-S silicic apatites, which grew from a silicic melt with an apparent maximum S concentration of ~ 80 ppm. Disparate apatite morphology (i.e. skeletal and acicular for basalt apatites and euhedral for silicic apatites) as well as compositional evidence reveal that high-S silicic apatites were not inherited from the juvenile basalt during mingling/mixing prior to eruption. Sulfur gain from neighboring anhydrite phenocrysts can also be ruled-out as a source of high sulfur. EMP sulfur mapping of silicic apatites shows highly irregular patterns of sulfur enrichment that do not correspond with adjacent anhydrite and can be found within apatites hosted by other minerals (e.g. hornblende and Fe-Ti oxides). With these data in mind, we propose high-S silicic apatites from Pinatubo and other sulfur-rich systems achieved elevated sulfur concentrations during high sulfur fluxing events that originated from underplated basalt during degassing of a SO2-rich fluid phase. That basalts were indeed sulfur rich and oxidized is here indicated by high S contents of apatites growing in basalt. The predominant location of S-rich areas of silicic apatite is crystal interiors of apatite inclusions in other mineral phases, while large apatite

  4. Synthesis of trace element bearing single crystals of Chlor-Apatite (Ca5(PO4)3Cl) using the flux growth method.

    Science.gov (United States)

    Klemme, Stephan; John, Timm; Wessels, Mathias; Kusebauch, Christof; Berndt, Jasper; Rohrbach, Arno; Schmid-Beurmann, Peter

    2013-01-01

    We present a new strategy on how to synthesize trace-element bearing (REE, Sr) chlorapatites Ca5(PO4)3Cl using the flux growth method. Synthetic apatites were up to several mm long, light blue in colour. The apatites were characterized using XRD, electron microprobe and laser ablation ICP-MS (LA-ICPMS) techniques and contained several hundred μg/g La, Ce, Pr, Sm, Gd and Lu and about 1700 μg/g Sr. The analyses indicate that apatites were homogenous (within the uncertainties) for major and trace elements. PMID:23531340

  5. Development of Biomimetic Needle-like Apatite Nanocrystals by a Simple New Method

    Institute of Scientific and Technical Information of China (English)

    Jie WEI; Yubao LI; Yi ZUO; Xueling PENG; Li ZHANG

    2004-01-01

    A new method of calcium nitrate and sodium phosphate as reactants was employed to prepare biomimetic apatite nanocrystals by a simple heating treatment in water. The structure and properties of the apatite crystals were investigated by TEM, XRD, IR, ICP and TG. It is found that the apatite nanocrystals contain OH-, CO32-, Na+ and HPO~- ions in their crystal structure. The crystal water is removed during heating from 200℃ to 400℃. CO32-and HPO~- are decomposed at 600℃ to 800℃, also there is lattice water lost at this temperature stage. The morphology of the apatite nanocrystals is needle-like with a length less than 80 nm. The size and crystallinity of the apatite nanocrystals increase with water treatment temperature and time. Compared to the apatite crystals sintered at 800℃, water treated apatite nanocrystals are poorly crystallized apatite. The results indicate that the apatite nanocrystals have similarity in composition, structure, morphology and crystallinity to that of bone apatite crystals. It can be used to make apatite crystals/polymer biomimetic bone repair materials or for other biomedical applications.

  6. Strongly bound citrate stabilizes the apatite nanocrystals in bone

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Y.-Y.; Rawal, A.; Schmidt-Rohr, K.

    2010-10-12

    Nanocrystals of apatitic calcium phosphate impart the organic-inorganic nanocomposite in bone with favorable mechanical properties. So far, the factors preventing crystal growth beyond the favorable thickness of ca. 3 nm have not been identified. Here we show that the apatite surfaces are studded with strongly bound citrate molecules, whose signals have been identified unambiguously by multinuclear magnetic resonance (NMR) analysis. NMR reveals that bound citrate accounts for 5.5 wt% of the organic matter in bone and covers apatite at a density of about 1 molecule per (2 nm){sup 2}, with its three carboxylate groups at distances of 0.3 to 0.45 nm from the apatite surface. Bound citrate is highly conserved, being found in fish, avian, and mammalian bone, which indicates its critical role in interfering with crystal thickening and stabilizing the apatite nanocrystals in bone

  7. Geochemistry of Apatite from the Apatite-rich Iron Deposits in the Ningwu Region, East Central China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Four types of apatite have been identified in the Ningwu region. The first type of apatite is widely distributed in the middle dark colored zones (i.e. iron ores) of individual deposits. The assemblage includes magnetite, apatite and actinolite (or diopside). The second type occurs within magnetite-apatite veins in the iron ores. The third type is seen in magnetite-apatite veins and (or)nodules in host rocks (i.e. gabbro-diorite porphyry or gabbro-diorite or pyroxene diorite).The fourth type occurs within apatite-pyrite-quartz veins filling fractures in the Xiangshan Group. Rare earth elements (REE) geochemistry of apatite of the four occurrences in porphyry iron deposits is presented. The REE distribution patterns of apatite are generally similar to those of apatites in the Kiruna-type iron ores, nelsonites. They are enriched in light REE, with pronounced negative Eu anomalies. The similarity of REE distribution patterns in apatites from various deposits in different locations in the world indicates a common process of formation for various ore types, e.g.immiscibility. Early magmatic apatites contain 3031.48-12080 ×10-6 REE. Later hydrothermal apatite contains 1958 ×10-6 REE, indicating that the later hydrothermai ore-forming solution contains lower REE. Although gabbro-diorite porphyry and apatite show similar REE patterns, gabbro-diorite porphyries have no europium anomalies or feeble positive or feeble negative europium anomalies,caused both by reduction environment of mantle source region and by fractionation and crystallization (immiscibility) under a high oxygen fugacity condition. Negative Eu anomalies of apatites were formed possibly due to acquisition of Eu2+ by earlier diopsite during ore magma cooling.The apatites in the Aoshan and Taishan iron deposits yield a narrow variation range of 87Sr/86Sr values from 0.7071 to 0.7073, similar to those of the volcanic and subvoicanic rocks, indicating that apatites were formed by liquid immiscibility and

  8. Hanford Apatite Treatability Test Report Errata: Apatite Mass Loading Calculation

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E.; Vermeul, Vincent R.; Williams, Mark D.; Truex, Michael J.

    2014-05-19

    The objective of this errata report is to document an error in the apatite loading (i.e., treatment capacity) estimate reported in previous apatite treatability test reports and provide additional calculation details for estimating apatite loading and barrier longevity. The apatite treatability test final report (PNNL-19572; Vermeul et al. 2010) documents the results of the first field-scale evaluation of the injectable apatite PRB technology. The apatite loading value in units of milligram-apatite per gram-sediment is incorrect in this and some other previous reports. The apatite loading in units of milligram phosphate per gram-sediment, however, is correct, and this is the unit used for comparison to field core sample measurements.

  9. Influence of cation substitution on the crystal structure and luminescent properties in apatite structural Ba4.97-xSrx(PO4)3Cl:0.03Eu2+ phosphors

    Science.gov (United States)

    Zhu, Ling; Huang, Zhaohui; Molokeev, Maxim S.; Min, Xin; Liu, Yangai; Fang, Minghao; Wu, Xiaowen

    2016-08-01

    A series of apatite-type phosphors Ba4.97-xSrx(PO4)3Cl:Eu2+(x = 0, 0.5, 1.0, 1.5, 2.0) were synthesized by the high temperature solid-state reaction method, and its luminescence properties were investigated in detail. It can be found that a red shift of the emission peak wavelength emerged from 439 to 462 nm with the continuous introduction of Sr2+ into the crystal lattice which has been simulated by a crystal-field model. The red shift is explained by the distortion in the crystal structure through X-ray diffraction and the Rietveld refinement analysis. According to a recently raised structural model, Eu2+ ions are surrounded by O atoms, PO4 tetrahedrons and Ba/Sr ions. After introducing Sr2+ into the lattice, the interatomic distance between Ba/Sr atoms and Eu2+ was expected to become shorter, resulting in a distortion of the inner EuOn polyhedrons. Then the crystal field strength surrounding Eu2+ was increased, finally resulting in the red shift.

  10. Ab initio constrained crystal-chemical Rietveld refinement of Ca{sub 10}(V{sub x}P{sub 1-x}O{sub 4}){sub 6}F{sub 2} apatites

    Energy Technology Data Exchange (ETDEWEB)

    Mercier, P.H.J.; Le Page, Y.; Whitfield, P.S. [National Research Council of Canada, Ottawa, ON (CA). Inst. for Chemical Process and Environmental Tech. (ICPET); Dong Zhili; Baikie, T.; White, T.J. [Nanyang Technological Univ., Singapore (Singapore). School of Materials Science and Engineering; Mitchel, L.D. [National Research Council of Canada, Ottawa, ON (CA). Inst. for Research in Construction (IRC)

    2007-02-15

    Extraction of reliable bond distances and angles for Ca{sub 10}(V{sub x}P{sub 1-x}O{sub 4}){sub 6}F{sub 2} apatites using standard Rietveld refinement with Cu K{sub {alpha}} X-ray powder data was significantly impaired by large imprecision for the O-atom coordinates. An initial attempt to apply crystal-chemical Rietveld refinements to the same compounds was partly successful, and exposed the problematic determination of two oxygen-metal- oxygen angles. Ab initio modeling with VASP in space groups P6{sub 3}/m, P2{sub 1}/m and Pm showed that both these angular parameters exhibited a linear dependence with the vanadium content. Stable crystal-chemical Rietveld refinements in agreement with quantum results were obtained by fixing these angles at the values from ab initio simulations. Residuals were comparable with the less precise standard refinements. The larger vanadium ion is accommodated primarily by uniform expansion and rotation of BO{sub 4} tetrahedra combined with a rotation of the Ca-Ca-Ca triangular units. It is proposed that the reduction of symmetry for the vanadium end-member is necessary to avoid considerable departures from formal valences at the A{sup II} and B sites in P6{sub 3}/m. The complementarity of quantum methods and structural analysis by powder diffraction in cases with problematic least-squares extraction of the crystal chemistry is discussed. (orig.)

  11. Biomimetic synthesis and biocompatibility evaluation of carbonated apatites template-mediated by heparin

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yi [Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Sun, Yuhua [Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081 (China); Chen, Xiaofang [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhu, Peizhi, E-mail: pzzhu@umich.edu [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Wei, Shicheng, E-mail: sc-wei@pku.edu.cn [Department of Oral and Maxillofacial Surgery, Laboratory of Interdisciplinary Studies, School and Hospital of Stomatology, Peking University, Beijing 100081 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China)

    2013-07-01

    Biomimetic synthesis of carbonated apatites with good biocompatibility is a promising strategy for the broadening application of apatites for bone tissue engineering. Most researchers were interested in collagen or gelatin-based templates for synthesis of apatite minerals. Inspired by recent findings about the important role of polysaccharides in bone biomineralization, here we reported that heparin, a mucopolysaccharide, was used to synthesize carbonated apatites in vitro. The results indicated that the Ca/P ratio, carbon content, crystallinity and morphology of the apatites varied depending on the heparin concentration and the initial pH value. The morphology of apatite changed from flake-shaped to needle-shaped, and the degree of crystallinity decreased with the increasing of heparin concentration. Biocompatibility of the apatites was tested by proliferation and alkaline phosphatase activity of MC3T3-E1 cells. The results suggested that carbonated apatites synthesized in the presence of heparin were more favorable to the proliferation and differentiation of MC3T3-E1 cells compared with traditional method. In summary, the heparin concentration and the initial pH value play a key role in the chemical constitution and morphology, as well as biological properties of apatites. These biocompatible nano-apatite crystals hold great potential to be applied as bioactive materials for bone tissue engineering. - Highlights: • Heparin was used as a template to synthesize needle-shaped nano-apatite. • Changing the pH value and concentration led to different properties of apatite. • Apatite prepared by heparin was more favorable to the osteogenic differentiation. • Possible synthesis mechanism of apatite templated by heparin was described.

  12. Biomimetic synthesis and biocompatibility evaluation of carbonated apatites template-mediated by heparin

    International Nuclear Information System (INIS)

    Biomimetic synthesis of carbonated apatites with good biocompatibility is a promising strategy for the broadening application of apatites for bone tissue engineering. Most researchers were interested in collagen or gelatin-based templates for synthesis of apatite minerals. Inspired by recent findings about the important role of polysaccharides in bone biomineralization, here we reported that heparin, a mucopolysaccharide, was used to synthesize carbonated apatites in vitro. The results indicated that the Ca/P ratio, carbon content, crystallinity and morphology of the apatites varied depending on the heparin concentration and the initial pH value. The morphology of apatite changed from flake-shaped to needle-shaped, and the degree of crystallinity decreased with the increasing of heparin concentration. Biocompatibility of the apatites was tested by proliferation and alkaline phosphatase activity of MC3T3-E1 cells. The results suggested that carbonated apatites synthesized in the presence of heparin were more favorable to the proliferation and differentiation of MC3T3-E1 cells compared with traditional method. In summary, the heparin concentration and the initial pH value play a key role in the chemical constitution and morphology, as well as biological properties of apatites. These biocompatible nano-apatite crystals hold great potential to be applied as bioactive materials for bone tissue engineering. - Highlights: • Heparin was used as a template to synthesize needle-shaped nano-apatite. • Changing the pH value and concentration led to different properties of apatite. • Apatite prepared by heparin was more favorable to the osteogenic differentiation. • Possible synthesis mechanism of apatite templated by heparin was described

  13. Insight into Biological Apatite: Physiochemical Properties and Preparation Approaches

    Directory of Open Access Journals (Sweden)

    Quan Liu

    2013-01-01

    Full Text Available Biological apatite is an inorganic calcium phosphate salt in apatite form and nano size with a biological derivation. It is also the main inorganic component of biological hard tissues such as bones and teeth of vertebrates. Consequently, biological apatite has a wide application in dentistry and orthopedics by using as dental fillers and bone substitutes for bone reconstruction and regeneration. Given this, it is of great significance to obtain a comprehensive understanding of its physiochemical and biological properties. However, upon the previous studies, inconsistent and inadequate data of such basic properties as the morphology, crystal size, chemical compositions, and solubility of biological apatite were reported. This may be ascribed to the differences in the source of raw materials that biological apatite are made from, as well as the effect of the preparation approaches. Hence, this paper is to provide some insights rather than a thorough review of the physiochemical properties as well as the advantages and drawbacks of various preparation methods of biological apatite.

  14. Study of damage and helium diffusion in fluoro-apatites

    International Nuclear Information System (INIS)

    This work lies within the scope of the study of the radionuclides containment matrices. The choice of the fluoro-apatites as potential matrices of containment was suggested by the notable properties of these latter (thermal and chemical stability even under radioactive radiation). By irradiations with heavy ions and a helium implantation we simulated the effects related to the alpha radioactivity and to the spontaneous nuclear fission of the radionuclides. Thanks to the study of Durango fluoro-apatite single crystals and fluoro-apatite sintered ceramics, we evidenced that the damage fraction as well as the unit cell deformations increase with the electronic energy loss and with the substitution. These effects are followed at high fluences by a phenomenon of re-crystallization. The study of the helium diffusion points out that the thermal diffusion process improves with the substitution and strongly increases with heavy ions irradiation. (author)

  15. Structure and Phase State of Bone Apatite of Calcified Aortic Fragments with Osteoporosis

    Directory of Open Access Journals (Sweden)

    Ya.V. Khyzhnya

    2013-10-01

    Full Text Available The paper represents the results of the study on the structure and phase composition of bone apatite and fragments of calcified aorta of the same experimental animal with model osteoporosis. Examination by the X-ray and electron diffraction, electron microscopy and infrared spectroscopy reveals that pathological calcification of rabbit aorta with model osteoporosis in crystal-chemical terms is the imperfect calcium apatite Ca10(PO46(OH2. Temperature growth of ectopic apatite crystals during annealing at 900C is similar to bioapatite of bone.

  16. Synthesis and Sintering Character of Nanophase Calcium-deficient Apatite

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Nanophase calcium-deficient hydroxyapatite( CDHA ) with a Ca/P ratio about 1.5 synthesized by chemical wet method was sintered at different temperatures, and then its chemical composition, phase structure and morphology were analyzed with methods of FT- IR spectroscopy, X- ray diffraction (XRD) and field emission scanning microscopy (FESEM), respectively. Results shaw that when the sintering temperature is below 500 ℃ ,apatite crystal keeps a stable size with a diameter of 12-26 nm and a length of 30-66 nm. After being sintered at600 ℃ for 2 h, apatite crystal grows much larger with a diameter of 25-40 nm and a length of 75-100 nm. At the temperature of 700-800 ℃, this powder decomposes into Ca3 ( PO4 )2 - The crystal size of the Ca3 ( PO4 )2surpasses 200 nm in diameter and length. NH4+ ion can be removed at terrperature beyond 300 ℃ .

  17. Apatite coating on anionic and native collagen films by an alternate soaking process.

    Science.gov (United States)

    Góes, J C; Figueiró, S D; Oliveira, A M; Macedo, A A M; Silva, C C; Ricardo, N M P S; Sombra, A S B

    2007-09-01

    The present study focuses on apatite coating on collagen films, with various different densities of carboxyl groups, using an alternate soaking process. Anionic collagen (AC), which has different densities of carboxylic groups compared to native collagen (NC), was obtained by hydrolysis of carboxyamides of asparagine and glutamine residues. From X-ray diffraction analysis, apatite was found to be coated on AC and NC films. Peaks ascribed to apatite were observed at 26 degrees and 32 degrees in the diffraction patterns of hydroxyapatite crystals. The amount of apatite coated on both AC and NC collagen films continued to increase up to 100 reaction cycles. However, there is a significant difference in apatite coating between the two films. The amount of apatite formed on the surface of AC film increased 1.24 times faster than on NC film. The scanning electron photomicrograph images of the mineralized NC and the AC film coatings formed after 100cycles show that regular porous apatite coating had formed within the collagen fibrils. These results suggest that the higher content of carboxyl groups in AC plays an effective role in the heterogeneous nucleation of apatite in the body environment.

  18. Biomimetic magnesium–carbonate-apatite nanocrystals endowed with strontium ions as anti-osteoporotic trigger

    Energy Technology Data Exchange (ETDEWEB)

    Iafisco, Michele, E-mail: michele.iafisco@istec.cnr.it; Ruffini, Andrea; Adamiano, Alessio; Sprio, Simone; Tampieri, Anna

    2014-02-01

    The present work investigates the preparation of biomimetic nanocrystalline apatites co-substituted with Mg, CO{sub 3} and Sr to be used as starting materials for the development of nanostructured bio-devices for regeneration of osteoporotic bone. Biological-like amounts of Mg and CO{sub 3} ions were inserted in the apatite structure to mimic the composition of bone apatite, whereas the addition of increasing quantities of Sr ions, from 0 up to 12 wt.%, as anti-osteoporotic agent, was evaluated. The chemical–physical features, the morphology, the degradation rates, the ion release kinetics as well as the in vitro bioactivity of the as-prepared apatites were fully evaluated. The results indicated that the incorporation of 12 wt.% of Sr can be viewed as a threshold for the structural stability of Mg–CO{sub 3}-apatite. Indeed, incorporation of lower quantity of Sr did not induce considerable variations in the chemical structure of Mg–CO{sub 3}-apatite, while when the Sr doping extent reached 12 wt.%, a dramatically destabilizing effect was detected on the crystal structure thus yielding alteration of the symmetry and distortion of the PO{sub 4}. As a consequence, this apatite exhibited the fastest degradation kinetic and the highest amount of Sr ions released when tested in physiological conditions. In this respect, the surface crystallization of new calcium phosphate phase when immersed in physiological-like solution occurred by different mechanisms and extents due to the different structural chemistry of the variously doped apatites. Nevertheless, all the apatites synthesized in this work exhibited in vitro bioactivity demonstrating their potential use to develop biomedical devices with anti-osteoporotic functionality. - Highlights: • Biomimetic nanocrystalline apatites co-substituted with Mg, CO{sub 3} and Sr were prepared. • Biological-like amounts of Mg and CO{sub 3} were inserted to mimic the composition of bone apatite. • The addition of increasing

  19. Endogenous Lunar Volatiles: Insights into the Abundances of Volatiles in the Moon from Lunar Apatite

    Science.gov (United States)

    McCubbin, Francis

    2016-01-01

    At the time of publication of New Views of the Moon, it was thought that the Moon was bone dry with less than about 1 ppb H2O. However in 2007, initial reports at the 38th Lunar and Planetary Science Conference speculated that H-species were present in both apatites and pyroclastic volcanic lunar glasses. These early reports were later confirmed through peer-review, which motivated many subsequent studies on magmatic volatiles in and on the Moon within the last decade. Some of these studies have cast into question the post-Apollo view of lunar formation, the distribution and sources of volatiles in the Earth-Moon system, and the thermal and magmatic evolution of the Moon. The mineral apatite has been one of the pillars of this new field of study, and it will be the primary focus of this abstract. Although apatite has been used both to understand the abundances of volatiles in lunar systems as well as the isotopic compositions of those volatiles, the focus here will be on the abundances of F, Cl, and H2O. This work demonstrates the utility of apatite in advancing our understanding of lunar volatiles, hence apatite should be among the topics covered in the endogenous lunar volatile chapter in NVM II. Truncated ternary plot of apatite X-site occupancy (mol%) from highlands apatite and mare basalt apatite plotted on the relative volatile abundance diagram from. The solid black lines delineate fields of relative abundances of F, Cl, and H2O (on a weight basis) in the melt from which the apatite crystallized. The diagram was constructed using available apatite/melt partitioning data for fluorine, chlorine, and hydroxyl.

  20. The study of geochemical behavior of rare earth elements in apatites from the Hormoz Island, Persian Gulf

    Directory of Open Access Journals (Sweden)

    Ali Rostami

    2014-04-01

    Full Text Available The study area is located about 3 km southwest of the Hormoz Island in the Hormozgan province, in the Persian Gulf. The main rock units in the region consist of a highly altered acidic pluton cratophyre, which is responsible for apatite formation, diabasic dike, marl and altered basalt. Apatite is the only phosphate mineral in the Hormoz Island, which has accumulated REE in its crystal structure. The amount of Na2O and SiO2 oxides in apatite are high and the average content of the main elements Fe, Mg, Al, Ca are 7.5 ppm, 365 ppm, 2880 ppm and 27.8%, respectively. The Y, Mn, Rb contents increase and Sr decreases with increasing magmatic differentiation. It shows that a moderate magmatic differentiation occurred during the crystallization of apatite. The total REE content in the Hormoz apatite is high (1.22-2.25%. LREE/HREE ratio is also high. This means that Hormoz apatites are enriched in light rare earth elements. The REE normalized pattern shows a negative slope with a negative Eu anomaly. According to various diagrams based on apatite composition, it is deduced that the Hormoz apatites belong to mafic I-type granitoids with high oxidation state (Fe2O3/FeO>1.

  1. Field Emission Electron Microprobe Analysis of Halogens in Apatite

    Science.gov (United States)

    Tacker, R. C.

    2011-12-01

    Field emission electron microprobe is capable of higher resolution and lower voltage than other microprobes, making it an ideal instrument for analysis of small accessory minerals in thin section such as apatite. In this study, the field emission electron microprobe was evaluated for analysis of fluorine and chlorine in apatite. Analysis was conducted on (001), (100) and an intermediate section of natural apatite crystals, using the JEOL JXA-8530F Hyperprobe, located at Fayetteville State University in Fayetteville, North Carolina. Conditions were beam current of 10 nanoamps, accelerating voltages from 5-20 kV, and spot sizes from 1-10 micrometers. Very short counting times were used, some as little as 2 seconds. Analytical strategies exploited the fact that excitation energies for fluorine Kα are much lower than for chlorine. Earlier studies (e.g. Stormer et al. 1993; Fialin and Chopin, 2006) documented the complex behavior of beam-driven migration, subsurface accumulation and desorption during fluorine analysis. The cumulative effect is increase and then fall of count rates with time and repeated analysis. The details of earlier studies were reproduced: (1) Apatite analysis by electron microprobe has two additional unknown variables, which are the crystallographic orientation of the unknown and of the standard. (2) The most reliable measure of fluorine cps is derived from a regression to zero time, accounting for crystal orientation; (3) Changing the analytical conditions (accelerating voltage, spot size, duration of analysis) changes only the time scale over which migration and desorption take place. New results from the JEOL Hyperprobe show that, for all crystal orientations, initial fluorine cps increase from 5 and 7 kV to 10 kV, but decrease systematically with further increases in kV, interpreted as loss of fluorine without concomitant excitation of X-rays. To date, fluorine analysis is routinely conducted at 15 and 20 kV. In contrast, chlorine initial

  2. Magnetite-apatite mineralization in Khanlogh iron deposit, northwest of Neyshaboor, NE Iran

    Science.gov (United States)

    Najafzadeh Tehrani, Parvin; Asghar Calagari, Ali; Velasco Roldan, Francisco; Simmonds, Vartan; Siahcheshm, Kamal

    2016-04-01

    Khanlogh iron deposit lies on Sabzehvar-Ghoochan Cenozoic magmatic belt in northwest of Neyshaboor, NE Iran. The lithologic units in this area include a series of sub-volcanic intrusive rocks like diorite porphyry, quartz-diorite porphyry, and micro-granodiorite of Oligocene age. Mineralization in this area occurred as veins, dissemination, and open space filling in brecciated zones within the host sub-volcanic intrusive bodies. Three distinct types of mineral associations can be distinguished, (1) diopside-magnetite, (2) magnetite-apatite, and (3) apatite-calcite. Microscopic examinations along with SEM and EPMA studies demonstrated that magnetite is the most common ore mineral occurring as solitary crystals. The euhedral magnetite crystals are accompanied by lamellar destabilized ilmenite and granular fluorapatite in magnetite-apatite ores. The results of EPMA revealed that the lamellar ilmenite, relative to host magnetite crystal, is notably enriched in MgO and MnO (average of 3.3 and 2.6 wt%, respectively; n=5), whereas magnetite is slighter enriched in Ti (TiO2 around 1.8 wt%) being average of MgO, MnO and V2O3 of 0.6wt%, 0.2wt%, and 0.6 wt% (respectively; n=20). Minerals such as chlorapatite, calcite, and chalcedony are also present in the magnetite-apatite ores. The samples from apatite-calcite ores contain coarse crystals of apatite and rhomboedral calcite. The plot of the EPMA data of Khanlogh iron ore samples on diagram of TiO2-V2O5 (Hou et al, 2011) illustrated that the data points lies between the well-known Kiruna and El Laco (Chile) iron deposits. The magnetite crystals in the sub-volcanic host rocks were possibly formed by immiscible iron oxide fluids during magmatic stage. However, the magnetite and apatite existing in the veins and breccia zones may have developed by high temperature hydrothermal fluids. Studies done by Purtov and Kotelnikova (1993) proved that the proportion of Ti in magnetite is related to fluoride complex in the hydrothermal

  3. Bioactivity of mica/apatite glass ceramics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The bioactivity of mica/apatite glass ceramic composites, including the in vitro behavior in simulated body fluid and the histological appearance of the interface between the mica/apatite glass ceramics and the rabbit mandible defect in vivo under a dynamic condition. The results show that biological apatite layer forms on the surface of the mica/apatite glass ceramics after 1 d of immersion in the simulated body fluid, and becomes dense after 14 d. In vivo tests indicate that bone formation occurs after implantation for 14 d, and strong bonding of bone to the implant occurs after 42 d. No aseptic loosening occurs during 42 d of implantation. The finding shows that mica/apatite glass ceramics have good bioactivity and osteoconductivity for constructing bone graft, and can be promising for biomedical application.

  4. Interrogating the Effects of Radiation Damage Annealing on Helium Diffusion Kinetics in Apatite

    Science.gov (United States)

    Willett, C. D.; Fox, M.; Shuster, D. L.

    2015-12-01

    Apatite (U-Th)/He thermochronology is commonly used to study landscape evolution and potential links between climate, erosion and tectonics. The technique relies on a quantitative understanding of (i) helium diffusion kinetics in apatite, (ii) an evolving 4He concentration, (iii) accumulating damage to the crystal lattice caused by radioactive decay[1], and (iv) the thermal annealing of such damage[2],[3], which are each functions of both time and temperature. Uncertainty in existing models of helium diffusion kinetics has resulted in conflicting conclusions, especially in settings involving burial heating through geologic time. The effects of alpha recoil damage annealing are currently assumed to follow the kinetics of fission track annealing (e.g., reference [3]), although this assumption is difficult to fully validate. Here, we present results of modeling exercises and a suite of experiments designed to interrogate the effects of damage annealing on He diffusivity in apatite that are independent of empirical calibrations of fission track annealing. We use the existing experimental results for Durango apatite[2] to develop and calibrate a new function that predicts the effects of annealing temperature and duration on measured diffusivity. We also present a suite of experiments conducted on apatite from Sierra Nevada, CA granite to establish whether apatites with different chemical compositions have the same behavior as Durango apatite. Crystals were heated under vacuum to temperatures between 250 and 500°C for 1, 10, or 100 hours. The samples were then irradiated with ~220 MeV protons to produce spallogenic 3He, the diffusant then used in step-heating diffusion experiments. We compare the results of these experiments and model calibrations to existing models. Citations: [1]Shuster, D., Flowers R., and Farley K., (2006), EPSL 249(3-4), 148-161; [2]Shuster, D. and Farley, K., (2009), GCA 73 (1), 6183-6196; [3]Flowers, R., Ketcham, R., Shuster, D. and Farley, K

  5. U-Pb Ages of Lunar Apatites

    Science.gov (United States)

    Vaughan, J.; Nemchin, A. A.; Pidgeon, R. T.; Meyer, Charles

    2006-01-01

    Apatite is one of the minerals that is rarely utilized in U-Pb geochronology, compared to some other U-rich accessory phases. Relatively low U concentration, commonly high proportion of common Pb and low closure temperature of U-Pb system of apatite inhibit its application as geochronological tool when other minerals such as zircon are widely available. However, zircon appear to be restricted to certain type of lunar rocks, carrying so called KREEP signature, whereas apatite (and whitlockite) is a common accessory mineral in the lunar samples. Therefore, utilizing apatite for lunar chronology may increase the pool of rocks that are available for U-Pb dating. The low stability of U-Pb systematics of apatite may also result in the resetting of the system during meteoritic bombardment, in which case apatite may provide an additional tool for the study of the impact history of the Moon. In order to investigate these possibilities, we have analysed apatites and zircons from two breccia samples collected during the Apollo 14 mission. Both samples were collected within the Fra Mauro formation, which is interpreted as a material ejected during the impact that formed the Imbrium Basin.

  6. Synthesis and Characterization of Tb-incorporated Apatite Nano-scale Powders

    Institute of Scientific and Technical Information of China (English)

    L.J. Sun; P.F. Ni; D.G. Guo; C.Q. Fang; J. Wang; F. Yang; X.F. Huang; Y.Z. Hao; H. Zhu; K.W. Xu

    2012-01-01

    Nano-scale Tb-incorporated apatite (nano-Tb-AP) particles with different Tb contents (Tb/(Tb+Ca)) of 0%, 5%, 10% and 20% were synthesized through a simple wet chemical method in this study. The crystal structure, thermal stabilities, chemical groups, crystal morphologies and crystal sizes of the nano--Tb-AP particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), respectively. It was found that lattice constants, particle sizes, crystalline and thermal stability varied with the doped Tb contents. With the increasing of Tb content, the lattice constants, particle size, length/diameter ratio, crystalline and thermal stability of nano-Tb-AP gradually decrease. Especially, almost all the 20%Tb-AP nano particles had been decomposed at 1200 ℃ while only a few of the decomposed products (β-TCP) were detected in the Tb-free nano apatite powders: This kind of nano-scale Tb-incorporated apatite exhibits an extremely potential clinic application because it integrates both the excellent biological functions of Tb element and apatite in human body.

  7. Characterization of a calcium phospho-silicated apatite with iron oxide inclusions

    Science.gov (United States)

    Desport, Barthélémy; Carpena, Joëlle; Lacout, Jean-Louis; Borschneck, Daniel; Gattacceca, Jérôme

    2011-02-01

    An iron oxide containing calcium phosphate-silicate hydroxyapatite was synthesized by calcination at 900 °C of a sample obtained by precipitation in basic aqueous solution of Ca, P, Si, Fe and Mg containing acidic solution made from dissolution of natural minerals. XRD and FTIR were used for crystallographic characterization of the main apatitic phase. Its composition was determined using ICP-AES. EDX coupled with SEM and TEM evidenced the heterogeneity of this compound and the existence of iron-magnesium oxide. Magnetic analyses highlighted that this phase was non-stoichiometric magnesioferrite (Mg 1.2Fe 1.8O 3.9) spherical nanoparticles. Those analyses also put into evidence the role of calcination in synthesis. Carbonates detected by FTIR and estimated by SEM-EDX in non-calcinated sample were removed from apatitic structure, and crystallization of apatite was enhanced during heating. Moreover, there was phase segregation that led to magnesioferrite formation.

  8. Microstructure and leach rates of apatite glass-ceramics as a host for Sr high-level liquid waste

    Science.gov (United States)

    He, Yong; Bao, Weimin; Song, Chongli

    2002-10-01

    An apatite glass-ceramic wasteform with 21 wt% SrO loading was fabricated for immobilizing Sr high-level liquid waste. The normalized leach rates of Sr, K, Mo, Al, P, Si are 6.9×10 -4, 1.09×10 -1, 2.7×10 -3, 3.22×10 -2, 2.84×10 -2, 3.26×10 -2 g/m 2 day, respectively. Component Fe in all leachates is not detectable in the 28-day static leaching test procedure in MCC-1. Instead of leaching, component Ca is adsorbed by testing samples. All the component Mo concentrates in the glass matrix of the well crystallized apatite glass-ceramics. For an apatite glass-ceramic wasteform, the optimum microstructure should be one in which poorly crystallized apatite crystallites distribute evenly in the glass phase. Perfect crystallization makes the crystal phase more stoichiometric and significantly changes the composition of the coexisting glass phase in the system, which, in our case, decreases the chemical stability of the apatite glass-ceramics.

  9. Hydrogen and carbon abundances and isotopic ratios in apatite from alkaline intrusive complexes, with a focus on carbonatites

    Energy Technology Data Exchange (ETDEWEB)

    Nadeau, S.L.; Epstein, S.; Stolper, E. [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences

    1999-06-01

    The authors report H and C contents and {delta}D and {delta}{sup 13}C values of apatites from 15 alkaline intrusive complexes ranging in age from 110 Ma to 2.6 Ga. Sampling focused on carbonatites, but included silicate rocks as well. Heating temperatures up to 1,500 C is needed to extract fully H{sub 2}O and CO{sub 2} from these apatites. Apatites from carbonatite-rich intrusive complexes contain 0.2--1.1 wt% H{sub 2}O and 0.05--0.70 wt% CO{sub 2}; apatites from two silicate-rich alkaline complexes with little or no carbonatite are generally poorer in both volatile components (0.1--0.2% H{sub 2}O and 0.01--0.11% CO{sub 2}). D/H ratios in apatites from these rocks are bimodally distributed. The authors suggest that the {delta}D values of group I apatites represent primitive, mantle-derived values and that the group II apatites crystallized from degassed magmas, resulting in lower H{sub 2}O contents and {delta}D values. In contrast to H{sub 2}O contents and {delta}D values, CO{sub 2} contents and {delta}{sup 13}C values of gas released at high temperatures from multiple aliquots of these apatite samples are variable. This suggests the presence of more than one C-bearing component in these apatites, one of which is proposed to be dissolved carbonate; the other could be associated with hydrocarbons.

  10. Apatite Formation: Why It May Not Work as Planned, and How to Conclusively Identify Apatite Compounds

    Directory of Open Access Journals (Sweden)

    Christophe Drouet

    2013-01-01

    Full Text Available Calcium phosphate apatites are inorganic compounds encountered in many different mineralized tissues. Bone mineral, for example, is constituted of nanocrystalline nonstoichiometric apatite, and the production of “analogs” through a variety of methods is frequently reported. In another context, the ability of solid surfaces to favor the nucleation and growth of “bone-like” apatite upon immersion in supersaturated fluids such as SFB is commonly used as one evaluation index of the “bioactivity” of such surfaces. Yet, the compounds or deposits obtained are not always thoroughly characterized, and their apatitic nature is sometimes not firmly assessed by appropriate physicochemical analyses. Of particular importance are the “actual” conditions in which the precipitation takes place. The precipitation of a white solid does not automatically indicate the formation of a “bone-like carbonate apatite layer” as is sometimes too hastily concluded: “all that glitters is not gold.” The identification of an apatite phase should be carefully demonstrated by appropriate characterization, preferably using complementary techniques. This review considers the fundamentals of calcium phosphate apatite characterization discussing several techniques: electron microscopy/EDX, XRD, FTIR/Raman spectroscopies, chemical analyses, and solid state NMR. It also underlines frequent problems that should be kept in mind when making “bone-like apatites.”

  11. The possibility of the formation of protocells and their structural components on the basis of the apatite matrix and cocrystallizing minerals.

    Science.gov (United States)

    Kostetsky, Eduard Y

    2005-12-01

    This paper presents the author's theory on the possibility of simultaneous hard-phase synthesis of various organic molecules from gas-phase elements on the basis of the apatite matrix and cocrystallizing minerals (carbonate-apatite, calcite, mica). These molecules and their ensembles gave rise to living systems and protocells of the pro- and eukaryotic types. Synthesis might have occurred through gradual substitution of the mineral matrix by crystal organic matter. The structure and size of the molecules synthesized were determined by the structure, physical parameters, and arrangement of organizing centers in the crystal lattice. Apatite phosphates were embedded in a synthesized nucleic helix and their size and purine-pyrimidine complementarity were determined. Apatite and cocrystallizing minerals were seen to be involved in the synthesis of four basic classes of cell components: apatite-DNA and nucleoproteide complexes; carbonate-apatite-enzymes, other proteins involved in DNA replication, all RNA types and their complexes with the specific proteins and enzymes of transcription and translation; calcite-cytoskeletal proteins; and mica-membrane lipids and proteins. The evidence supporting this theory is presented. A possible mechanism to account for the transition from crystal through organo-mineral crystal to liquid crystal (protocell) and a model of the occurrence of the matrix mechanism of transcription and translation are proposed. Some principal problems in the biochemistry and molecular biology of the origin of life on the Earth are discussed. PMID:23345922

  12. Biomimetic growth and substrate dependent mechanical properties of bone like apatite nucleated on Ti and magnetron sputtered TiO2 nanostructure

    Science.gov (United States)

    Sarma, Bimal K.; Das, Apurba; Barman, Pintu; Pal, Arup R.

    2016-04-01

    This report presents findings on biomimetic growth of hydroxyapatite (HAp) nanocrystals on Ti and sputtered TiO2 substrates. The possibility of TiO2 nanostructure as candidate materials for future biomedical applications has been explored through the comparison of microstructural and mechanical properties of bone like apatite grown on Ti and nano-TiO2 surfaces. Raman spectroscopy and x-ray diffraction studies reveal formation of carbonate apatite with apparent domain size in the nanoscale range. A better interaction at the nano-TiO2/nano-HAp interface due to higher interfacial area could promote the growth of bone like apatite. The crystal phases, crystallinity, and surface morphology of nano-TiO2 are considered as parameters to understand the nucleation and growth of apatite with different mechanical properties at the nanoscale. The methodology of x-ray line profile analysis encompasses deconvolution of merged peaks by preserving broadening due to nanosized HAp aggregates. The Young’s modulus of bone like apatite exhibits crystallographic directional dependence which suggests the presence of elastic anisotropy in bone like apatite. The lattice contraction in the c-direction is associated with the degree of carbonate substitution in the apatite lattice. The role of residual stress is critical for the lattice distortion of HAp deposited at physiological conditions of temperature and pH of human blood plasma. The ion concentration is crucial for the uniformity, crystallinity, and mechanical behaviour of the apatite.

  13. A temporal record of pre-eruptive magmatic volatile contents at Campi Flegrei: Insights from texturally-constrained apatite analyses

    Science.gov (United States)

    Stock, Michael J.; Isaia, Roberto; Humphreys, Madeleine C. S.; Smith, Victoria C.; Pyle, David M.

    2016-04-01

    Apatite is capable of incorporating all major magmatic volatile species (H2O, CO2, S, Cl and F) into its crystal structure. Analysis of apatite volatile contents can be related to parental magma compositions through the application of pressure and temperature-dependent exchange reactions (Piccoli and Candela, 1994). Once included within phenocrysts, apatite inclusions are isolated from the melt and preserve a temporal record of magmatic volatile contents in the build-up to eruption. In this work, we measured the volatile compositions of apatite inclusions, apatite microphenocrysts and pyroxene-hosted melt inclusions from the Astroni 1 eruption of Campi Flegrei, Italy (Stock et al. 2016). These data are coupled with magmatic differentiation models (Gualda et al., 2012), experimental volatile solubility data (Webster et al., 2014) and thermodynamic models of apatite compositional variations (Piccoli and Candela, 1994) to decipher pre-eruptive magmatic processes. We find that apatite halogen/OH ratios decreased through magmatic differentiation, while melt inclusion F and Cl concentrations increased. Melt inclusion H2O contents are constant at ~2.5 wt%. These data are best explained by volatile-undersaturated differentiation over most of the crystallisation history of the Astroni 1 melt, with melt inclusion H2O contents reset at shallow levels during ascent. Given the high diffusivity of volatiles in apatite (Brenan, 1993), the preservation of volatile-undersaturated melt compositions in microphenocrysts suggests that saturation was only achieved 10 - 103 days before eruption. We suggest that late-stage transition into a volatile-saturated state caused an increase in magma chamber overpressure, which ultimately triggered the Astroni 1 eruption. This has major implications for monitoring of Campi Flegrei and other similar volcanic systems. Piccoli and Candela, 1994. Am. J. of Sc., 294, 92-135. Stock et al., 2016, Nat. Geosci. Gualda et al., 2012. J. Pet., 53, 875

  14. Preparation, characterization and in vitro evaluation of nanostructured chitosan/apatite and chitosan/Si-doped apatite composites

    OpenAIRE

    Solis, Yaimara; Davidenko, Natalia; Carrodeguas, Raul G.; Cruz, Jeny; Hernandez, Andy; Tomas, Miriela; Cameron, Ruth Elizabeth; Peniche, Carlos

    2013-01-01

    Chitosan/apatite composites are attracting great attention as biomaterials for bone repair and regeneration procedures. The reason is their unique set of properties: bioactivity and osteoconductivity provided by apatite and resorbability supplied by chitosan among others. Thus, in this work chitosan/apatite and chitosan/Si-doped apatite composites were prepared and characterized. Particle size, surface area, in vitro physiological stability, enzymatic biodegradation and bioactivity were evalu...

  15. Radionuclide Incorporation and Long Term Performance of Apatite Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianwei [Louisiana State Univ., Baton Rouge, LA (United States); Lian, Jie [Rensselaer Polytechnic Inst., Troy, NY (United States); Gao, Fei [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-01-04

    This project aims to combines state-of-the-art experimental and characterization techniques with atomistic simulations based on density functional theory (DFT) and molecular dynamics (MD) simulations. With an initial focus on long-lived I-129 and other radionuclides such as Cs, Sr in apatite structure, specific research objectives include the atomic scale understanding of: (1) incorporation behavior of the radionuclides and their effects on the crystal chemistry and phase stability; (2) stability and microstructure evolution of designed waste forms under coupled temperature and radiation environments; (3) incorporation and migration energetics of radionuclides and release behaviors as probed by DFT and molecular dynamics (MD) simulations; and (4) chemical durability as measured in dissolution experiments for long term performance evaluation and model validation.

  16. The Possibility of the Formation of Protocells and Their Structural Components on the Basis of the Apatite Matrix and Cocrystallizing Minerals

    OpenAIRE

    Kostetsky, Eduard Y.

    2005-01-01

    This paper presents the author's theory on the possibility of simultaneous hard-phase synthesis of various organic molecules from gas-phase elements on the basis of the apatite matrix and cocrystallizing minerals (carbonate-apatite, calcite, mica). These molecules and their ensembles gave rise to living systems and protocells of the pro- and eukaryotic types. Synthesis might have occurred through gradual substitution of the mineral matrix by crystal organic matter. The structure and size of t...

  17. Preparation of fluoride substituted apatite cements as the building blocks for tooth enamel restoration

    International Nuclear Information System (INIS)

    Fluoride substituted apatite cement (fs-AC) was synthesized by using the cement powders of tetracalcium phosphate (TTCP) and sodium fluoride (NaF), and the cement powders were mixed with diluted phosphoric acid (H3PO4) as cement liquid to form fs-AC paste. The fs-AC paste could be directly filled into the carious cavities to repair damaged dental enamel. The results indicated that the fs-AC paste was changed into fluorapatite crystals with the atom molar ratio for calcium to phosphorus of 1.66 and the F ion amount of 3 wt% after self-hardening for 2 days. The solubility of fs-AC in Tris-HCl solution (pH 6) was slightly lower than hydroxyapatite cement (HAC) that was similar to the apatite in enamel, indicating the fs-AC was much insensitive to the weakly acidic solution than the apatite in enamel. The fs-AC was tightly combined with the enamel surface because of the chemical reaction between the fs-AC and the apatite in enamel after the caries cavities was filled with fs-AC. The extracts of fs-AC caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. The fs-AC had potential prospect for the reconstitution of carious lesion of dental enamel.

  18. Preparation of fluoride substituted apatite cements as the building blocks for tooth enamel restoration

    Energy Technology Data Exchange (ETDEWEB)

    Wei Jie [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China); Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Wang Jiecheng; Liu Xiaochen [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China); Ma Jian [Hospital of Stomatology, Tongji University, Shanghai 200072 (China); Liu Changsheng [Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Fang Jing, E-mail: biomater2006@yahoo.com.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China); Wei Shicheng, E-mail: nic7505@263.net [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China) and School and Hospital of Stomatology, Peking University, Beijing 100081 (China)

    2011-06-15

    Fluoride substituted apatite cement (fs-AC) was synthesized by using the cement powders of tetracalcium phosphate (TTCP) and sodium fluoride (NaF), and the cement powders were mixed with diluted phosphoric acid (H{sub 3}PO{sub 4}) as cement liquid to form fs-AC paste. The fs-AC paste could be directly filled into the carious cavities to repair damaged dental enamel. The results indicated that the fs-AC paste was changed into fluorapatite crystals with the atom molar ratio for calcium to phosphorus of 1.66 and the F ion amount of 3 wt% after self-hardening for 2 days. The solubility of fs-AC in Tris-HCl solution (pH 6) was slightly lower than hydroxyapatite cement (HAC) that was similar to the apatite in enamel, indicating the fs-AC was much insensitive to the weakly acidic solution than the apatite in enamel. The fs-AC was tightly combined with the enamel surface because of the chemical reaction between the fs-AC and the apatite in enamel after the caries cavities was filled with fs-AC. The extracts of fs-AC caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. The fs-AC had potential prospect for the reconstitution of carious lesion of dental enamel.

  19. Bone-like apatite coating on functionalized poly(etheretherketone) surface via tailored silanization layers technique

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yanyan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xiong, Chengdong; Zhang, Shenglan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Li, Xiaoyu [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, Lifang, E-mail: zhanglfcioc@163.com [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China)

    2015-10-01

    Poly(etheretherketone) (PEEK) is a rigid semi-crystalline polymer with outstanding mechanical properties, bone-like stiffness and suitable biocompatibility that has attracted much interest as a biomaterial for orthopedic and dental implants. However, the bio-inert surface of PEEK limits its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, –PO{sub 4}H{sub 2}, –COOH and –OH groups were introduced on the PEEK surface by further chemical treatments of the vinyl-terminated silanization layers formed on the hydroxylation-pretreated PEEK surface. Both the surface-functionalized and pristine specimens were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and water contact angle measurements. When placed in 1.5 strength simulated body fluid (SBF) solution, apatite was observed to form uniformly on the functionalized PEEK surface and firmly attach to the substrate. The characterized results demonstrated that the coating was constituted by poorly crystallized bone-like apatite and the effect of surface functional groups on coating formation was also discussed in detail. In addition, in vitro biocompatibility of PEEK, in terms of pre-osteoblast cell (MC3T3-E1) attachment, spreading and proliferation, was remarkably enhanced by the bone-like apatite coating. Thus, this study provides a method to enhance the bioactivity of PEEK and expand its applications in orthopedic and dental implants. - Highlights: • –PO{sub 4}H{sub 2}, –COOH and –OH groups were successfully introduced onto PEEK surface via tailored silanization layer technique. • Bone-like apatite formed uniformly on surface-functionalized PEEK after immersion in SBF, and tightly adhered to the PEEK. • SEM, EDS, FTIR, XPS and XRD results showed that apatite layer is composed of low-crystalline bone-like apatite. • Bone-like apatite coating

  20. Apatite-forming ability and magnetic properties of glass-ceramics containing zinc ferrite and calcium sodium phosphate phases

    International Nuclear Information System (INIS)

    Fine particles of zinc ferrite (ZnFe2O4) and calcium sodium phosphate [NaCaPO4] were crystallized in bulk x(ZnO, Fe2O3)(65-x)SiO220(CaO, P2O5)15Na2O (6 ≤ x ≤ 21 mol %) glassy matrix by heat treatment. Initial magnetization curves reveal that samples with x = 6 and 9 mol % zinc-iron oxide exhibit both ferrimagnetic and paramagnetic contributions, whereas, samples with x > 9 mol % zinc-iron oxide exhibit only ferrimagnetic contribution. This observation is supported by the disappearance of the electron paramagnetic resonance (EPR) absorption line centered at g ∼ 4.3 in samples with x > 9 mol % zinc-iron oxide. Apatite-forming ability of the glass-ceramic samples was investigated by examining apatite formation on the surface of the samples treated in simulated body fluid (SBF). Increase in apatite-forming ability was observed with an increase in zinc-iron oxide content. The results obtained have been used to understand the evolution of the apatite surface layer as a function of immersion time in SBF and glass-ceramic composition. A good correlation has also been observed between the magnetic nature of the samples and their apatite-forming ability. These materials are expected to find application as thermo-seeds in hyperthermia treatment of bone cancer.

  1. Immobilizing hydroxycholesterol with apatite on titanium surfaces to induce ossification

    OpenAIRE

    Chen, Cen; Yang, Hyeong Cheol; Lee, In-Seop

    2014-01-01

    Background Immobilizing bioactive molecules and osteoconductive apatite on titanium implants have investigated direct ossification. In this study, hydroxycholesterol (HC) was immobilized with apatite on titanium through simply adsorption or sandwich-like coating. Three kinds of hydroxycholesterol were chosen to induce ossification: 20α-hydroxycholesterol (20α- HC), 22(S)-hydroxycholesterol (22(S)-HC) and 25-hydroxycholesterol (25-HC).The effects of HC/apatite coating on ossification abilities...

  2. Reactive backfills in radioactive waste disposal selenium sorption on apatite

    International Nuclear Information System (INIS)

    Apatites are investigated as possible high performance material for reactive backfills in radioactive waste disposal. An experimental study showed an excellent selenite retaining rate and established the main characteristic of this element sorption on natural and synthetic apatites. Thermodynamical parameters have been calculated and integrated in a geochemical computer code in order to demonstrate the excellent potentialities of the apatite as a trap mineral for the selenium. (A.L.B.)

  3. RBS and RNRA studies on sorption of europium by apatite

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, Toshihiko; Kozai, Naofumi; Isobe, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Murakami, Takashi; Yamamoto, Shunya; Aoki, Yasushi; Naramoto, Hiroshi

    1997-03-01

    The sorption mechanism of europium, alternative of trivalent TRU has been studied based on the depth profiles of elements obtained by Rutherford Backscattering Spectroscopy (RBS) and Resonant Nuclear Reaction Analysis (RNRA). The positive peak for Eu and the negative peak for Ca were observed in the subtracted RBS spectra of the apatites on which Eu was sorbed from that of the fresh apatite. This indicates that Eu was sorbed on apatite, while a fraction of Ca was released from apatite. The peak height for Eu in the RBS spectrum of the apatite obtained at 75degC was higher than that of the apatite at 40degC. The depth profile of hydrogen of the apatite on which Eu was sorbed was similar to that of the fresh apatite. The concentration of Eu in the solution decreased with increasing temperature. On the contrary, the concentration of Ca increased with increasing temperature. Thus, it is concluded that a fraction of Eu is exchanged for Ca in the structure of apatite. (author)

  4. Characterization of mesostasis regions in lunar basalts: Understanding late-stage melt evolution and its influence on apatite formation

    Science.gov (United States)

    Potts, Nicola J.; TartèSe, Romain; Anand, Mahesh; Westrenen, Wim; Griffiths, Alexandra A.; Barrett, Thomas J.; Franchi, Ian A.

    2016-07-01

    Recent studies geared toward understanding the volatile abundances of the lunar interior have focused on the volatile-bearing accessory mineral apatite. Translating measurements of volatile abundances in lunar apatite into the volatile inventory of the silicate melts from which they crystallized, and ultimately of the mantle source regions of lunar magmas, however, has proved more difficult than initially thought. In this contribution, we report a detailed characterization of mesostasis regions in four Apollo mare basalts (10044, 12064, 15058, and 70035) in order to ascertain the compositions of the melts from which apatite crystallized. The texture, modal mineralogy, and reconstructed bulk composition of these mesostasis regions vary greatly within and between samples. There is no clear relationship between bulk-rock basaltic composition and that of bulk-mesostasis regions, indicating that bulk-rock composition may have little influence on mesostasis compositions. The development of individual melt pockets, combined with the occurrence of silicate liquid immiscibility, exerts greater control on the composition and texture of mesostasis regions. In general, the reconstructed late-stage lunar melts have roughly andesitic to dacitic compositions with low alkali contents, displaying much higher SiO2 abundances than the bulk compositions of their host magmatic rocks. Relevant partition coefficients for apatite-melt volatile partitioning under lunar conditions should, therefore, be derived from experiments conducted using intermediate compositions instead of compositions representing mare basalts.

  5. Characterization of mesostasis regions in lunar basalts: Understanding late-stage melt evolution and its influence on apatite formation

    Science.gov (United States)

    Potts, Nicola J.; TartèSe, Romain; Anand, Mahesh; Westrenen, Wim; Griffiths, Alexandra A.; Barrett, Thomas J.; Franchi, Ian A.

    2016-09-01

    Recent studies geared toward understanding the volatile abundances of the lunar interior have focused on the volatile-bearing accessory mineral apatite. Translating measurements of volatile abundances in lunar apatite into the volatile inventory of the silicate melts from which they crystallized, and ultimately of the mantle source regions of lunar magmas, however, has proved more difficult than initially thought. In this contribution, we report a detailed characterization of mesostasis regions in four Apollo mare basalts (10044, 12064, 15058, and 70035) in order to ascertain the compositions of the melts from which apatite crystallized. The texture, modal mineralogy, and reconstructed bulk composition of these mesostasis regions vary greatly within and between samples. There is no clear relationship between bulk-rock basaltic composition and that of bulk-mesostasis regions, indicating that bulk-rock composition may have little influence on mesostasis compositions. The development of individual melt pockets, combined with the occurrence of silicate liquid immiscibility, exerts greater control on the composition and texture of mesostasis regions. In general, the reconstructed late-stage lunar melts have roughly andesitic to dacitic compositions with low alkali contents, displaying much higher SiO2 abundances than the bulk compositions of their host magmatic rocks. Relevant partition coefficients for apatite-melt volatile partitioning under lunar conditions should, therefore, be derived from experiments conducted using intermediate compositions instead of compositions representing mare basalts.

  6. Apatite trace element and halogen compositions as petrogenetic-metallogenic indicators: Examples from four granite plutons in the Sanjiang region, SW China

    Science.gov (United States)

    Pan, Li-Chuan; Hu, Rui-Zhong; Wang, Xin-Song; Bi, Xian-Wu; Zhu, Jing-Jing; Li, Chusi

    2016-06-01

    The abundances of trace elements including Sr, Ga and rare earth elements (REE) and halogens in apatite crystals from four intermediate-felsic plutons in the Zhongdian terrane in the Sanjiang region have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometry to evaluate the potential of apatite as a petrogenic-metallogenic indicator. The selected plutons include one that is not mineralized (the Triassic Xiuwacu pluton, or the TXWC pluton), one that hosts a porphyry-type Cu deposit (the Pulang pluton, or the PL pluton), one that hosts a porphyry-type Mo deposit (the Tongchanggou pluton, or the TCG pluton), and one that hosts a vein-type Mo deposit (the Cretaceous Xiuwacu pluton, or the CXWC pluton). Except for the CXWC pluton, the other three plutons have adakite-like trace element signatures in whole rocks. The results from this study show that REE, Sr and halogens in apatite can be used to track magma compositions, oxidation states and crystallization history. Apatite crystals from the adakite-like plutons are characterized by much higher Sr/Y and δEu than the non-adakite-type pluton. This means that apatite, which is not susceptible to alteration, is a useful tool for identifying the adakite-like plutons that no longer preserve the initial Sr/Y ratios in whole rocks due to weathering and hydrothermal alteration. Based on apatite Ga contents and δEu values, it is inferred that the parental magmas for the two adakite-like plutons containing porphyry-type Cu and Mo mineralization are more oxidized than that for the non-adakite-type pluton containing vein-type Mo mineralization. Apatite crystals from the vein-type Mo deposit have much lower Cl/F ratios than those from the porphyry-type Cu and Mo deposits. Apatite crystals from the adakite-like pluton without Cu or Mo mineralization is characterized by much lower Cl/F ratios than those from the adakite-like plutons that host the porphyry-type Cu and Mo deposits. The

  7. Possible secondary apatite fission track age standard from altered volcanic ash beds in the middle Jurassic Carmel Formation, Southwestern Utah

    Science.gov (United States)

    Kowallis, B.J.; Christiansen, E.H.; Everett, B.H.; Crowley, K.D.; Naeser, C.W.; Miller, D.S.; Deino, A.L.

    1993-01-01

    Secondary age standards are valuable in intra- and interlaboratory calibration. At present very few such standards are available for fission track dating that is older than Tertiary. Several altered volcanic ash beds occur in the Middle Jurassic Carmel Formation in southwestern Utah. The formation was deposited in a shallow marine/sabhka environment. Near Gunlock, Utah, eight ash beds have been identified. Sanidines from one of the ash beds (GUN-F) give a single-crystal laser-probe 40Ar/39Ar age of 166.3??0.8 Ma (2??). Apatite and zircon fission track ages range from 152-185 Ma with typically 15-20 Ma errors (2??). Track densities in zircons are high and most grains are not countable. Apatites are fairly common in most of the ash beds and have reasonable track densities ranging between 1.2-1.5 ?? 106 tracks/cm2. Track length distributions in apatites are unimodal, have standard deviations <1??m, and mean track lengths of about 14-14.5 ??m. High Cl apatites (F:Cl:OH ratio of 39:33:28) are particularly abundant and large in ash GUN-F, and are fairly easy to concentrate, but the concentrates contain some siderite, most of which can be removed by sieving. GUN-F shows evidence of some reworking and detriaal contamination based on older single grain 40Ar/39Ar analyses and some rounding of grains, but the apatite population appears to be largely uncontaminated. At present BJK has approximately 12 of apatite separate from GUN-F. ?? 1993.

  8. Study of damage and helium diffusion in fluoro-apatites; Etude de l'endommagement et de la diffusion de l'helium dans des fluoroapatites

    Energy Technology Data Exchange (ETDEWEB)

    Miro, S

    2004-12-15

    This work lies within the scope of the study of the radionuclides containment matrices. The choice of the fluoro-apatites as potential matrices of containment was suggested by the notable properties of these latter (thermal and chemical stability even under radioactive radiation). By irradiations with heavy ions and a helium implantation we simulated the effects related to the alpha radioactivity and to the spontaneous nuclear fission of the radionuclides. Thanks to the study of Durango fluoro-apatite single crystals and fluoro-apatite sintered ceramics, we evidenced that the damage fraction as well as the unit cell deformations increase with the electronic energy loss and with the substitution. These effects are followed at high fluences by a phenomenon of re-crystallization. The study of the helium diffusion points out that the thermal diffusion process improves with the substitution and strongly increases with heavy ions irradiation. (author)

  9. Production of spherical apatite powders—the first step for optimized thermal-sprayed apatite coatings

    Science.gov (United States)

    Lugscheider, E.; Knepper, M.; Gross, K. A.

    1992-09-01

    Regardless of the thermal spraying system, a coating can only be as good as the quality of the input powders. Powder quality in turn is dependent on the manufacturing process and conditions. Thus, it is possible to alter characteristics such as morphology, porosity, phase composition, and the mechanical strength of the individual particles. This article looks at powder agglomerations using the spray drying technique. Two different spray drying configurations were used to produce spherical apatite powders. Apatite powders could be produced with variable densities. Rotary-atomized powders possessed internal porosity as well as open porosity. More applicable for thermal spraying are the nozzle-atomized powders, which are more dense. The particle size range produced is dependent on the many parameters in the spray drying process. Hydroxyapatite is more sensitive than fluorapatite to alterations in process conditions. The powders produced were clean, free of other phases, and possessed good flowability for thermal spraying purposes.

  10. From natural to synthetic apatites: the use of apatites as conditioning material for separated nuclear wastes

    International Nuclear Information System (INIS)

    The minerals with an apatite structure formed two billion years ago during natural nuclear reactions in Oklo (Gabon) are phospho-silicate apatites called britholites. In the lattice, they contain as substitutions or inclusions radioactive elements or the fission products. They remain totally stable and appear to be excellent to be excellent nuclear waste conditioning materials. From these observations, the study of synthetics britholites was carried out. The optimal chemical composition was determined, solid/solid synthesis was performed and the stability under radioactive, thermal conditions was studied in relation to geological observations. The first results indicating resistance to radiation and leaching open a supplementary way for the preparation of conditioning material for separated nuclear waste. (authors)

  11. Biomimetic synthesis of poly(lactic-co-glycolic acid/multi-walled carbon nanotubes/apatite composite membranes

    Directory of Open Access Journals (Sweden)

    H. L. Zhang

    2012-08-01

    Full Text Available Bioactive guided tissue regeneration (GTR membrane has had some success for periodontal therapy. In this study, poly(lactic-co-glycolic acid (PLGA/multi-walled carbon nanotubes (MWNTs composite membranes were incubated in three supersaturated calcification solutions (SCS of different pH values for 21 days to prepare a PLGA/MWNTs/apatite composite. Scanning electron microscope (SEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, energy dispersive spectroscopy (EDS, water contact angle measurement and mechanical testing were used for characterization. It was found that after 21 days incubation, apatite with low crystallite size and crystallinity was formed on the PLGA/MWNTs composite membranes. The Ca-poor carbapatite was similar in morphology and composition to that of natural bone. The size and shape of the apatite crystals immersed in three SCS were different from each other. The hydrophilicity and mechanical properties of the PLGA/MWNTs composite membranes were significantly enhanced after mineralization. This indicated that biomimetic mineralization may be an effective method to improve the biocompatibility and bone inductivity of certain materials. The PLGA/MWNTs/apatite composites may be potentially useful in GTR applications, particularly as GTR membranes for periodontal tissue regeneration.

  12. The chitosan prepared from crab tendons: II. The chitosan/apatite composites and their application to nerve regeneration.

    Science.gov (United States)

    Yamaguchi, Isamu; Itoh, Soichiro; Suzuki, Masumi; Osaka, Akiyoshi; Tanaka, Junzo

    2003-08-01

    The chitosan tubes derived from crab tendons form a hollow tube structure, which is useful for nerve regeneration. However, in order to use the chitosan tubes effectively for nerve regeneration, there remain two problems to be solved. First, the mechanical strength of the tubes is quite high along the longitudinal axis, but is somewhat low for a pressure from side. Second, the chitosan tube walls swell to reduce the inner space of the tubes in vivo. These two problems limit the clinical use of the chitosan tubes. In this study, to solve the problems, apatite was made to react with the chitosan tubes to enhance the mechanical strength of the tube walls. Transmission electron microscopy showed that apatite crystals were formed in the walls of the chitosan tubes. The c-axis of the crystals aligned well in parallel with chitosan molecules. These results indicate that the apatite crystals grow in the tubes starting from the nucleation sites of the chitosan molecules, probably by forming complexes with amino groups of chitosan and calcium ions. Further, the tubes were thermally annealed at 120 degrees C to prevent from swelling, and simultaneously formed into a triangular shape to enhance the stabilization of the tube structure. By these treatments, the hollow tubes could keep their shape even in vivo after implantation. Animal tests using SD rats further showed that the chitosan tubes effectively induced the regeneration of nerve tissue, and were gradually degraded and absorbed in vivo.

  13. Effect of osteonectin-derived peptide on the viscoelasticity of hydrogel/apatite nanocomposite scaffolds.

    Science.gov (United States)

    Sarvestani, Alireza S; He, Xuezhong; Jabbari, Esmaiel

    2007-03-01

    Hydrogel/apatite nanocomposites are the ideal biomaterial to mimic the physio-chemical and biologic properties of the bone and to fabricate scaffolds for bone regeneration. The objective of this work was to investigate the effect of an osteonectin derived glutamic acid sequence on the viscoelastic properties of poly(lactide-ethylene oxide-fumarate) (PLEOF)/apatite composite, as a model degradable material in bone regeneration. Osteonectin is an extracellular acidic glycoprotein of the bone matrix, which is believed to be involved in linking the collagen network to hydroxyapatite (HA), the mineral phase of the bone. We synthesized a 6-glutamic acid sequence in solid phase with affinity to HA crystals via ionic interactions. One end of the synthesized peptide was functionalized with an acrylate group to covalently attach the peptide (Ac-Glu6) to the aqueous-based biodegradable and in situ crosslinkable PLEOF hydrogel matrix. To determine the effect of energetic interactions between the fillers and hydrogel matrix, HA nanoparticles were also treated with an acrylate functionalized 6-glycine amino acid peptide (Ac-Gly6) that interacts with the fillers only by van der Waals and polar interactions (without ionic interactions). Crosslinked PLEOF/apatite scaffolds were prepared using PLEOF as the degradable macromer, HA nanofillers treated with Ac-Glu6 peptide linker, and a neutral redox initiation system. The viscoelastic properties were studied by dynamic time sweep, strain sweep, and small amplitude oscillatory rheometry. Composites without surface treatment, treated with Ac-Gly6, and treated with Ac-Glu6 at different volume fractions and various particle sizes were examined. The results showed that the 6-mer glutamic acid sequence significantly affects the shear modulus of the scaffold because of ionic interactions between the peptide and HA crystals. PMID:17183515

  14. Development of Tributyl Phosphate Apatite for Uranium Removal

    International Nuclear Information System (INIS)

    The FTIR results showed that main peaks were shown at 3570 cm-1 in all materials. The band around at 3570 cm-1 indicates the stretching hydroxyl group from HA. Phosphate functional group was observed around at 1040 cm-1. The C-H containing functional group (3000-2950 cm-1) was found only in the TBP-apatite prepared at pH=10 condition. Uranium removal was evaluated under different reaction times, initial U concentrations, and background solution using synthesized HA and TBP-apatite. As NaHCO3 concentration increased, U removal decreased. In the same condition, TBP-apatite showed better U removal than HA, which indicates TBP-apatite can be used as U removal sorbent

  15. EPR dosimetry with synthetic A-type carbonated apatite

    International Nuclear Information System (INIS)

    Synthetic A-type carbonated apatite prepared in reproducible conditions were irradiated at room temperature with 60 Co γ rays. The EPR spectrum is associated to axial CO2- and orthorhombic CO3- species. Radicals used as dose marker in biological apatite are long live paramagnetic species. The stability of the post-irradiation signal of A-type apatite was investigated for more than one year. Measurements showed variations in the spectra attributed to unstable CO3- species, which can be eliminated by thermal treatments at 100 deg C for 24 hours. The CO2- spectrum can be identified in samples irradiated up to 0.2 Gy. All results indicate the A-type apatite as an appropriate material for radiotherapy dosimetry. (author)

  16. Development of Tributyl Phosphate Apatite for Uranium Removal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, HyunJu; Kang, Jaehyuk; Kim, Jungjin; Uma, Wooyong [POSTECH, Daejeon (Korea, Republic of)

    2015-05-15

    The FTIR results showed that main peaks were shown at 3570 cm-1 in all materials. The band around at 3570 cm-1 indicates the stretching hydroxyl group from HA. Phosphate functional group was observed around at 1040 cm-1. The C-H containing functional group (3000-2950 cm-1) was found only in the TBP-apatite prepared at pH=10 condition. Uranium removal was evaluated under different reaction times, initial U concentrations, and background solution using synthesized HA and TBP-apatite. As NaHCO{sub 3} concentration increased, U removal decreased. In the same condition, TBP-apatite showed better U removal than HA, which indicates TBP-apatite can be used as U removal sorbent.

  17. Genesis of rare-metal pegmatites and alkaline apatite-fluorite rocks of Burpala massi, Northern Baikal folded zone

    Science.gov (United States)

    Sotnikova, Irina; Vladykin, Nikolai

    2015-04-01

    thermobarometric evidence suggests that apatite-fluorite rocks were formed from the residual fluid-melt, separated after crystallization of rare-metal pegmatites. Petrochemical and geochemical data Burpalinsky are in accord of general trend of crystal differentiation of alkaline magma containing small concentrations of CO2 and higher P2O5 and F, which accumulated significantly separated from the pegmatite melts. In some pegmatites fluorite with rare-metal minerals (flyuocerit etc) are separating in schlieren. Apatite-fluorite rocks are cut by leucogranite dyke, having genetic connection with rare-metal pegmatites. Late granitic phases has its own association of rare-metal minerals described by A.A. Ganzeev (1972). Thermobarometric geochemical study of apatite-fluorite rocks Burpala massif found a large number of primary fluid inclusions (15-50 micrometers). Thermal and cryometric research of 60 individual fluid inclusions in fluorite showed the domination of Na, Ca, Mg chlorides and high temperatures salt inclusions in fluorites (above 550C) and melt inclusions in apatites (800C). Apatite-fluorite rocks in massif are similar to foskorites in carbonatite complexes, with similar high Ca content, but instead fluorite, together with other "foskoritovymi" minerals - apatite, magnetite, mica, and pyroxene were formed instead for calcite. Isotopic studies (Sr-Nd) indicate the mantle source of primary magma Burpala massif close to EM-2, which is characteristic of alkaline intrusions in the folded belts (Vladykin 2009). RBRF grant 14-45-04057

  18. Synthesis and characterization of nanocrystalline apatites from solution modeling human blood

    Science.gov (United States)

    Solodyankina, Anna; Nikolaev, Anton; Frank-Kamenetskaya, Olga; Golovanova, Olga

    2016-09-01

    Present paper is devoted to the research of the calcification processes in the blood plasma of human body. Spontaneous crystallization from the solution modeling the inorganic part of the blood plasma has been carried out. Obtained precipitates were studied by the various instrumental methods (X-ray powder diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, electron probe microanalysis and gas-volumetric method). All gathered data allow to summarize that nonstoichiometric carbonated hydroxyapatite with low crystallinity (CSD lengths 18-28 nm), high water content and small amount of chlorine ion was obtained throughout the syntheses. Part of vacancies at the Ca sites varies from 0.17 to 0.87; the value of the Cat/(P + C) ratio-from 1.52 to 1.64 (where Cat = Ca2+ + Na+ + K+ + Mg2+). The poor crystallized synthetic apatites with high carbonate ion content (from 4.34 to 5.54 wt%) and c parameter (6.888-6.894 Å) are analogues of the apatites of the pathological cardiovascular deposits. They can be obtained from the solution modeling human blood plasma by the inorganic components with calcium phosphate supersaturation 25 and 50 and with 10 and 12 weeks experiment time.

  19. Model Evaluation the Effect of Size, Shape and Surface Condition of Apatite Nanocrystals on the Deviation of Ca / P ratio from stoichiometric

    Directory of Open Access Journals (Sweden)

    S.N. Danilchenko

    2014-04-01

    Full Text Available The causes of Са / Р ratio deviation in biological apatites from stoichiometric one were discussed. By the simple model evaluation Са / Р ratio was shown to deviate from stoichiometric one because of small sizes of crystals, and peculiarities in chemical composition of their facets. Also size effect is noted to be unsufficient for explanation of wide variations of Са / Р ratio in biological apatites. It proves the significant contribution of lattice isovalent and heterovalent substitution into variability of Са / Р ratio. The problem of revealing the predominant causes of Са / Р deviation from stoichiometric one and estimation of their relative contribution is related to determination of the functional role of the structural imperfections in biological apatites of different origin.

  20. Apatite U-Pb thermochronolgy applied to complex geological settings - insights from geo/thermochronology and geochemistry

    Science.gov (United States)

    Paul, Andre; Spikings, Richard; Ulyanov, Alexey; Chew, David

    2016-04-01

    Application of high temperature (>350oC) thermochronology is limited to the U-Pb system of accessory minerals, such as apatite, under the assumption that radiogenic lead is lost to thermally activated volume diffusion into an infinite reservoir. Cochrane et al. (2015) have demonstrated a working example from the northern Andes of South America. Predictions from volume diffusion theory were compared with measured single grain U-Pb date correlated to shortest diffusion radius and in-situ profiles measured by LA-ICP-MS. Results from both techniques were found to be in agreement with predictions from thermally activated, volume diffusion. However, outliers from the ID-TIMS data suggested some complexity, as grains were found to be too young relative to their diffusion radius. Interaction of multiple processes can be responsible for the alteration of apatite U-Pb dates such as: (1) metamorphic (over)growth, (2) fluid aided alteration/recrystallization and (3) metamictization and fracturing of the grain. Further, predictions from volume diffusion rely on the input parameters: (a) diffusivity, (b) activation energy and (c) shortest diffusion radius. Diffusivity and activation energy are potentially influenced by the chemical composition and subsequent changes in crystal structure. Currently there is one value for diffusion parameter and activation energy established for (Durango) apatite (Cherniak et al., 1991). Correlation between diffusivity/activation energy and composition has not been established. We investigate if correlations exist between diffusivity/activation energy and composition by obtaining single grain apatite U-Pb date and chemical compostion and correlating these to their diffusion radius. We test the consistency of apatite closure temperature, by comparing the apatite U-Pb dates with lower temperature thermochronometers such as white mica and K-feldspar Ar/Ar and by petrographic observations. We test if chemical information can be a proxy to identify

  1. Polytopic Vector Analysis (PVA) modelling of whole-rock and apatite chemistry from the Karkonosze composite pluton (Poland, Czech Republic)

    Science.gov (United States)

    Lisowiec, Katarzyna; Słaby, Ewa; Förster, Hans-Jürgen

    2015-08-01

    This study presents a novel approach for analysing the magma evolution path in composite plutons, applying the so-termed Polytopic Vector Analysis (PVA) to whole-rock and apatite chemistry. As an example of a multiphase magmatic body the Karkonosze granitoid pluton was chosen, which formed by a combination of magma mixing and fractional crystallization of two distinct melts - granitic crust-derived and lamprophyric mantle-derived. The goal was to model end-member magma compositions recorded by apatite and to estimate to what extent these end-members interacted with each other. Although using single minerals as proxies to magma compositions is tricky, the studied apatite well reflects the compositional trends within the magma (e.g., decreasing LREE/Y ratios, varying halogen content, increasing Mn and Na concentrations). The results of PVA simulations for whole-rock geochemistry demonstrate a model similar to that constrained from previous studies. Apart from the main trend of mixing between a felsic (~ 80 wt.% SiO2) and a mafic (~ 53 wt.% SiO2) end-member (EM), an additional process has been recognized, representing most probably the continuous evolution of the mafic end-member, responsible for the compositional diversity of some rocks. One felsic (REE-poor, Mn-F-rich) and one mafic (Cl-Sr-Si-REE-rich) apatite end-members were recognized, whereas the third one represents most probably a fluid component (enriched in Si, Y, Ce and Nd), present at all magmatic stages, however, most prominent during the late stage. The widest range of EM proportions and the highest contribution of the mafic EM are displayed by apatites from the early stage. During the middle and late stages, the apatites present a narrow range of EM proportions, with almost all apatites bearing a felsic signature. This pattern reflects the progressive homogenization of the system. Although the PVA method applied to mineral chemistry poses some limitations, it may provide a more detailed image of the

  2. Adsorption of DNA on biomimetic apatites: Toward the understanding of the role of bone and tooth mineral on the preservation of ancient DNA

    Science.gov (United States)

    Grunenwald, A.; Keyser, C.; Sautereau, A. M.; Crubézy, E.; Ludes, B.; Drouet, C.

    2014-02-01

    In order to shed some light on DNA preservation over time in skeletal remains from a physicochemical viewpoint, adsorption and desorption of DNA on a well characterized synthetic apatite mimicking bone and dentin biominerals were studied. Batch adsorption experiments have been carried out to determine the effect of contact time (kinetics), DNA concentration (isotherms) and environmentally relevant factors such as temperature, ionic strength and pH on the adsorption behavior. The analogy of the nanocrystalline carbonated apatite used in this work with biological apatite was first demonstrated by XRD, FTIR, and chemical analyses. Then, DNA adsorption kinetics was fitted with the pseudo-first order, pseudo-second order, Elovich, Ritchie and double exponential models. The best results were achieved with the Elovich kinetic model. The adsorption isotherms of partially sheared calf thymus DNA conformed satisfactorily to Temkin's equation which is often used to describe heterogeneous adsorption behavior involving polyelectrolytes. For the first time, the irreversibility of DNA adsorption toward dilution and significant phosphate-promoted DNA desorption were evidenced, suggesting that a concomitant ion exchange process between phosphate anionic groups of DNA backbone and labile non-apatitic hydrogenphosphate ions potentially released from the hydrated layer of apatite crystals. This work should prove helpful for a better understanding of diagenetic processes related to DNA preservation in calcified tissues.

  3. Apatite at Olympic Dam, South Australia: A petrogenetic tool

    Science.gov (United States)

    Krneta, Sasha; Ciobanu, Cristiana L.; Cook, Nigel J.; Ehrig, Kathy; Kontonikas-Charos, Alkis

    2016-10-01

    The > 10,000 million tonne Olympic Dam Cu-Au-U-Ag deposit, (eastern Gawler Craton, South Australia) is one of the largest orebodies in the World. The deposit is hosted within the Olympic Dam Breccia Complex, placed at the centre of, and resulting from multiple brecciation and Fe-metasomatism of the Roxby Downs Granite (RDG). The latter is part of a larger batholith emplaced at ~ 1.6 Ga. Apatite petrography and chemistry were studied in non-mineralised RDG and coeval granitoids and dolerites, as well as in mineralised RDG from deep (> 2 km) and distal (2.7 km to NE) locations. In both latter cases, although the mineralisation corresponds to the same, early chalcopyrite-pyrite-magnetite ± hematite stage identified in the outer and deeper zones of the deposit itself, the character of granite alteration differs: sericite-chlorite alteration with all feldspar replaced in the deep location; and red-stained K-feldspar on top of prevailing albitization in the distal location. Close-to end-member fluorapatite is a key accessory mineral in all igneous rocks and a common product of early hydrothermal alteration within mineralised granite. Variations in habit, morphology and textures correlate with chemical trends expressed as evolving Cl/F ratios, and concentrations of REE + Y (hereafter REY), Sr, Mn, S, Si and Na. Magmatic apatite is unzoned in the dolerite but features core to REY-enriched rim zonation in the granitoids. Increases in Cl- and Sr-contents correlate with rock basicity. Calculation of Cl in the vapour phase relative to melt at the apatite saturation temperature for zoned apatite in the RDG shows higher values for grains with inclusion-rich cores associated with mafic enclaves, concordant with assimilation of exotic material during magma crystallisation. Hydrothermal alteration of magmatic apatite is most varied in the dolerite where interaction with fluids is expressed as subtle changes in Cl- versus F- and REY-enrichment, and most importantly, S-enrichment in

  4. UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium

    Directory of Open Access Journals (Sweden)

    Saita M

    2016-01-01

    Full Text Available Makiko Saita,1 Takayuki Ikeda,1,2 Masahiro Yamada,1,3 Katsuhiko Kimoto,4 Masaichi Chang-Il Lee,5 Takahiro Ogawa1 1Division of Advanced Prosthodontics, Weintraub Center for Reconstructive Biotechnology, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Yokosuka, Japan; 3Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan; 4Department of Prosthodontics and Oral Rehabilitation, 5Yokosuka-Shonan Disaster Health Emergency Research Center and ESR Laboratories, Kanagawa Dental University Graduate School of Dentistry, Yokosuka, Japan Background: Although biomimetic apatite coating is a promising way to provide titanium with osteoconductivity, the efficiency and quality of deposition is often poor. Most titanium implants have microscale surface morphology, and an addition of nanoscale features while preserving the micromorphology may provide further biological benefit. Here, we examined the effect of ultraviolet (UV light treatment of titanium, or photofunctionalization, on the efficacy of biomimetic apatite deposition on titanium and its biological capability.Methods and results: Micro-roughed titanium disks were prepared by acid-etching with sulfuric acid. Micro-roughened disks with or without photofunctionalization (20-minute exposure to UV light were immersed in simulated body fluid (SBF for 1 or 5 days. Photofunctionalized titanium disks were superhydrophilic and did not form surface air bubbles when immersed in SBF, whereas non-photofunctionalized disks were hydrophobic and largely covered with air bubbles during immersion. An apatite-related signal was observed by X-ray diffraction on photofunctionalized titanium after 1 day of SBF immersion, which was equivalent to the one observed after 5 days of immersion of control titanium. Scanning electron microscopy revealed nodular apatite deposition

  5. Incorporating 3-D parent nuclide zonation for apatite 4He/3He thermochronometry: An example from the Appalachian Mountains

    Science.gov (United States)

    Fox, Matthew; McKeon, Ryan E.; Shuster, David L.

    2014-11-01

    ability to constrain km-scale exhumation with apatite 4He/3He thermochronometry is well established and the technique has been applied to a range of tectonic and geomorphic problems. However, multiple sources of uncertainty in specific crystal characteristics limit the applicability of the method, especially when geologic problems require identifying small perturbations in a cooling path. Here we present new 4He/3He thermochronometric data from the Appalachian Mountains, which indicate significant parent nuclide zonation in an apatite crystal. Using LA-ICPMS measurements of U and Th in the same crystal, we design a 3-D model of the crystal to explore the effects of intracrystal variability in radiation damage accumulation. We describe a numerical approach to solve the 3-D production-diffusion equation. Using our numerical model and a previously determined time temperature path for this part of the Appalachians, we find excellent agreement between predicted and observed 4He/3He spectra. Our results confirm this time-temperature path and highlight that for complex U and Th zonation patterns, 3-D numerical models are required to infer an accurate time-temperature history. In addition, our results provide independent and novel evidence for a radiation damage control on diffusivity. The ability to exploit intracrystal differences in 4He diffusivity [i.e., temperature sensitivity) greatly increases the potential to infer complex thermal histories.

  6. Increase of apatite dissolution rate by Scots pine roots associated or not with Burkholderia glathei PML1(12)Rp in open-system flow microcosms

    Science.gov (United States)

    Calvaruso, Christophe; Turpault, Marie-Pierre; Frey-Klett, Pascale; Uroz, Stéphane; Pierret, Marie-Claire; Tosheva, Zornitza; Kies, Antoine

    2013-04-01

    and organic acids" experiment demonstrated that the apatite dissolution efficacy of organic acids was higher than for the inorganic acid and varied in function of the acids: oxalic acid > citric acid > gluconic acid > nitric acid for pH ⩽3.5. In addition, apatite dissolution increased with increasing acidity for each acid. Only oxalic acid generated non-stoichiometric release of calcium and phosphorus from apatite in the solution at pH ⩽3.5, due to the precipitation of Ca-oxalate crystals at apatite surfaces. Comparison of the experiments revealed that the apatite dissolution rate by Scots pines supplied with nutritive solution at pH 5.5 reached 2.0 × 10-13 mol cm-2 s-1 and was equivalent to rates with nitric acid at pH 3.2, gluconic acid at pH 3.5, citric acid at pH 3.7, and oxalic acid at pH 3.8. Altogether our results highlight that, through the production of weathering agents, notably protons and organic acids, tree roots and root-associated microorganisms are able to significantly increase the release of macro- and micro-nutrients from apatite, thus maintaining high-nutrient conditions to support their growth.

  7. Study of the auto-irradiation effects in apatites structure materials; Etude des effets d'auto-irradiation dans des materiaux a structure apatitique

    Energy Technology Data Exchange (ETDEWEB)

    Soulet, St

    2000-11-15

    decreases rapidly with the increase of SiO{sub 4}/PO{sub 4} ratio; this is in agreement with the conclusions of the study with natural analogous. It decreases also when the fluor anion is replaced by an hydroxyl group. With the current knowledge, the annealing by alpha seems to be an unique property of the apatitic structure. In order to model the behavior of ceramics when they are doped with actinides, it has been established, with defects creation and recovery velocities, the differential equation of the disorder evolution in terms of the storage or disposal time. The resolution of this equation in the case of the phospho-calcic fluoro-apatite and the fluoro-apatite with one silicate allows to conclude that these two potential matrices will probably keep their crystal structure during the storage or the disposal. (O.M.)

  8. Nanodimensional and Nanocrystalline Apatites and Other Calcium Orthophosphates in Biomedical Engineering, Biology and Medicine

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2009-11-01

    Full Text Available Recent developments in biomineralization have already demonstrated that nanosized particles play an important role in the formation of hard tissues of animals. Namely, the basic inorganic building blocks of bones and teeth of mammals are nanodimensional and nanocrystalline calcium orthophosphates (in the form of apatites of a biological origin. In mammals, tens to hundreds nanocrystals of a biological apatite were found to be combined into self-assembled structures under the control of various bioorganic matrixes. In addition, the structures of both dental enamel and bones could be mimicked by an oriented aggregation of nanosized calcium orthophosphates, determined by the biomolecules. The application and prospective use of nanodimensional and nanocrystalline calcium orthophosphates for a clinical repair of damaged bones and teeth are also known. For example, a greater viability and a better proliferation of various types of cells were detected on smaller crystals of calcium orthophosphates. Thus, the nanodimensional and nanocrystalline forms of calcium orthophosphates have a great potential to revolutionize the field of hard tissue engineering starting from bone repair and augmentation to the controlled drug delivery devices. This paper reviews current state of knowledge and recent developments of this subject starting from the synthesis and characterization to biomedical and clinical applications. More to the point, this review provides possible directions of future research and development.

  9. Interstitial Oxide Ion Distribution and Transport Mechanism in Aluminum-Doped Neodymium Silicate Apatite Electrolytes.

    Science.gov (United States)

    An, Tao; Baikie, Tom; Orera, Alodia; Piltz, Ross O; Meven, Martin; Slater, Peter R; Wei, Jun; Sanjuán, María L; White, T J

    2016-04-01

    Rare earth silicate apatites are one-dimensional channel structures that show potential as electrolytes for solid oxide fuel cells (SOFC) due to their high ionic conductivity at intermediate temperatures (500-700 °C). This advantageous property can be attributed to the presence of both interstitial oxygen and cation vacancies, that create diffusion paths which computational studies suggest are less tortuous and have lower activation energies for migration than in stoichiometric compounds. In this work, neutron diffraction of Nd(28+x)/3AlxSi6-xO26 (0 ≤ x ≤ 1.5) single crystals identified the locations of oxygen interstitials, and allowed the deduction of a dual-path conduction mechanism that is a natural extension of the single-path sinusoidal channel trajectory arrived at through computation. This discovery provides the most thorough understanding of the O(2-) transport mechanism along the channels to date, clarifies the mode of interchannel motion, and presents a complete picture of O(2-) percolation through apatite. Previously reported crystallographic and conductivity measurements are re-examined in the light of these new findings. PMID:27015162

  10. Apatite weathering as a geological driver of high uranium concentrations in groundwater

    International Nuclear Information System (INIS)

    Highlights: • High groundwater U concentrations occur in a Triassic aquifer of northern Bavaria. • U is hosted by carbonate fluorapatite phases (francolite) in aquifer inclusions. • Distribution of uraniferous facies is congruent with spatial groundwater U pattern. • Carbonate substitution and α-recoil damage from U decay enhance mineral solubility. • Mobilization of U to groundwater occurs during francolite weathering. - Abstract: Uranium is a heavy metal with potential adverse human health effects when consumed via drinking water. Although associated quality regulations have been implemented, geological sources and hydrogeochemical behavior of uranium in groundwater used for drinking water supply remain little understood. This study presents a hydrogeochemical and mineralogical characterization of a Triassic sandstone aquifer on a macro- and micro-scale, and an evaluation of uranium remobilization into groundwater, also considering the paleoenvironment and the distribution of the affected aquifer itself. Syndiagenetic uraniferous carbonate fluorapatite inclusions within the aquifer sandstones (“active arkoses”) were found to show structurally (chemical substitution in the crystal structure) and radiatively (α-recoil damage from uranium decay) enhanced mineral solubility. Extraction experiments indicated that these inclusions release uranium to groundwater during weathering. In conclusion, apatite alteration was identified as the responsible mechanism for widespread groundwater uranium concentrations >10 μg L−1 in the region representing Germany’s most significant problem area in this respect. Therefore, results indicate that the studied sedimentary apatite deposits cause the regional geogenic groundwater uranium problem, and must be considered as potential uranium sources in comparable areas worldwide

  11. Thermodynamic Properties of Sulfatian Apatite: Constraints on the Behavior of Sulfur in Calc-Alkaline Magmas

    Science.gov (United States)

    Core, D.; Essene, E. J.; Luhr, J. F.; Kesler, S. E.

    2004-12-01

    The Gibbs free energy of hydroxyellestadite [Ca10(SiO4)3(SO4)3(OH)2] was estimated using mineral equilibria applied to analyzed assemblages from the experimental charges of Luhr (1990). The apatite analyses of Peng et al. (1997) were used in conjunction with new analyses of the oxides and silicates in this study. An ideal mixing model was employed for apatite combined with mixing models from MELTS (Ghiorso & Sack, 1994) and Gibbs free energy data from Robie & Hemingway (1995) for the other crystalline phases. The resultant equation of the Gibbs free energy vs. T for hydroxyellestadite is as follows: DG°T(elem) = [2.817(T - 273) - 11831]/1000 kJ/mol, T in K. The calculated entropy for hydroxyellestadite is 1944 J/mol.K at 1073 K and 2151 J/mol.K at 1227 K. Independent estimates of the entropy of hydroxyellestadite obtained with the method of Robinson & Haas (1983) are within 5% of these values. The thermodynamic data on hydroxyellestadite were used to calculate the locus of the reactions: 2Ca10(SiO4)3(SO4)3(OH)2 + 7S2 + 21O2 = 20CaSO4 + 6SiO2 + 2H2O 6Ca10(SiO4)3(SO4)3(OH)2 + 102SiO2 + 20Fe3O4 = 60CaFeSi2O6 + 6H2O + 9S2 + 37O2 2Ca10(SiO4)3(SO4)3(OH)2 + 10Mg2Si2O6 + 14SiO2 = 20CaMgSi2O6 + 2H2O + 3S2 + 9O2 in fO2-fS2 space at fixed P-T. Application of these equilibria to apatite zoned in sulfate from oxidized granitoids reflects a drop in fS2 by more than 1 log unit during its growth. The zoning is interpreted to represent the removal of a magmatic vapor phase during crystallization of these plutons. Removal of sulfur from magmas by hydrothermal fluids is important to the ore-forming process and to the production of acid sulfate aerosols during eruption of oxidized magmas. Preservation of sulfatian apatite may yield data on the sulfidation states of ancient flood basalts such as the Deccan Traps of India and the Parana basalts of Brazil to address the environmental impact of these giant eruptions.

  12. Depressing effect of sodium hexametaphosphate on apatite in flotation of rutile

    Institute of Scientific and Technical Information of China (English)

    Hao Ding; Hai Lin; Yanxi Deng

    2007-01-01

    The separation of mtile from apatite by flotation and the mechanism of depressing the apatite of sodium hexametaphosphate were studied. The results showed that rutile and apatite could be separated by using alkyl-imino-bismethylene phosphoric acid and sodium hexametaphosphate as a collector and a regulator, respectively. Sodium hexametaphosphate could selectively dissolve calcium ions on the apatite surface, and make calcium ions break away from lattice binding through combining.

  13. Revisiting the localization of Zn2+ cations sorbed on pathological apatite calcifications made through X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bazin, D.; Carpentier, X.; Brocheriou, I.; Dorfmuller, P.; Aubert, S.; Chappard, C.; Thiaudiere, D.; Reguer, S.; Waychunas, G.; Jungers, P.; Daudon, M.

    2009-04-01

    The role of oligo-elements such as Zn in the genesis of pathological calcifications is widely debated in the literature. An essential element of discussion is given by their localization either at the surface or within the Ca apatite crystalline network. To determine the localization, X-ray absorption experiments have been performed at SOLEIL. The Exafs results suggest that Zn atoms, present in the Zn{sup 2+} form, are bound to about 4 O atoms at a distance of 2.00{angstrom}, while the interatomic distance R{sub CaO} ranges between 2.35 {angstrom} and 2.71 {angstrom}. Taking into account the content of Zn (around 1000 ppm) and the difference in ionic radius between Zn{sup 2+} (0.074 nm) and Ca{sup 2+} (0.099 nm), a significant longer interatomic distance would be expected in the case of Zn replacing Ca within the apatite crystalline network. We thus conclude that Zn atoms are localized at the surface and not in the apatite nanocrystal structure. Such structural result has essential biological implications for at least two reasons. Some oligoelements have a marked effect on the transformation of chemical phases, and may modify the morphology of crystals. These are both major issues because, in the case of kidney stones, the medical treatment depends strongly on the precise chemical phase and on the morphology of the biological entities at both macroscopic and mesoscopic scales.

  14. Carbon and oxygen isotopes in apatite CO2 and co-existing calcite

    International Nuclear Information System (INIS)

    Carbon and oxygen isotopes were analyzed in carbonate apatite CO2 and in co-existing calcite. Both C and O in apatite CO2 are enriched in the respective light isotopes relative to calcite. These results confirm the proposition that carbonate is part of the apatite structure

  15. REE partitioning between apatite and melt in a peralkaline volcanic suite, Kenya Rift Valley

    Science.gov (United States)

    Macdonald, R.; Baginski, B.; Belkin, H.E.; Dzierzanowski, P.; Jezak, L.

    2009-01-01

    Electron microprobe analyses are presented for fluorapatite phenocrysts from a benmoreite-peralkaline rhyolite volcanic suite from the Kenya Rift Valley. The rocks have previously been well characterized petrographically and their crystallization conditions are reasonably well known. The REE contents in the M site increase towards the rhyolites, with a maximum britholite component of ~35 mol.%. Chondrite-normalized REE patterns are rather flat between La and Sm and then decrease towards Yb. Sodium and Fe occupy up to 1% and 4%, respectively, of the M site. The major coupled substitution is REE3+ + Si4+ ??? Ca2+ + P5+. The substitution REE3+ + Na+ ??? 2Ca2+ has been of minor importance. The relatively large Fe contents were perhaps facilitated by the low fo2 conditions of crystallization. Zoning is ubiquitous and resulted from both fractional crystallization and magma mixing. Apatites in some rhyolites are relatively Y-depleted, perhaps reflecting crystallization from melts which had precipitated zircon. Mineral/glass (melt) ratios for two rhyolites are unusually high, with maxima at Sm (762, 1123). ?? 2008 The Mineralogical Society.

  16. Lead Speciation and Bioavailability in Apatite-Amended Sediments

    Directory of Open Access Journals (Sweden)

    Kirk G. Scheckel

    2011-01-01

    Full Text Available The in situ sequestration of lead (Pb in sediment with a phosphate amendment was investigated by Pb speciation and bioavailability. Sediment Pb in preamendment samples was identified as galena (PbS with trace amounts of absorbed Pb. Sediment exposed to atmospheric conditions underwent conversion to hydrocerussite and anglesite. Sediments mixed with apatite exhibited limited conversion to pyromorphite, the hypothesized end product. Conversion of PbS to pyromorphite is inhibited under reducing conditions, and pyromorphite formation appears limited to reaction with pore water Pb and PbS oxidation products. Porewater Pb values were decreased by 94% or more when sediment was amended with apatite. The acute toxicity of the sediment Pb was evaluated with Hyalella azteca and bioaccumulation of Pb with Lumbriculus variegatus. The growth of H. azteca may be mildly inhibited in contaminated sediment, with apatite-amended sediments exhibiting on average a higher growth weight by approximately 20%. The bioaccumulation of Pb in L. variegatus tissue decreased with increased phosphate loading in contaminated sediment. The study indicates limited effectiveness of apatite in sequestering Pb if present as PbS under reducing conditions, but sequestration of porewater Pb and stabilization of near-surface sediment may be a feasible and alternative approach to decreasing potential toxicity of Pb.

  17. Apatite-structured compounds: Synthesis and high-temperature investigation

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Alexander V.; Chernorukov, Nikolai G. [Nizhny Novgorod State University, Gagarin Prospekt 23/2, 603950 Nizhny Novgorod (Russian Federation); Bulanov, Evgeny N., E-mail: bulanoven@yandex.ru [Nizhny Novgorod State University, Gagarin Prospekt 23/2, 603950 Nizhny Novgorod (Russian Federation)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer 25 Apatite-structured compounds of different composition were synthesized. Black-Right-Pointing-Pointer Phase transformations of them in wide temperature interval were investigated. Black-Right-Pointing-Pointer For the first time polymorphic transitions were observed on 6 apatites. Black-Right-Pointing-Pointer Thermal expansion coefficients of all studied phases were calculated. Black-Right-Pointing-Pointer The direct communication between thermal stability and expansion anisotropy was observed. - Abstract: The phase transitions and thermal expansion of apatite-structured compounds with the general formula M{sup II}{sub 5}(A{sup V}O{sub 4}){sub 3}L (M{sup II} = Ca, Sr, Cd, Ba, Pb; A{sup V} = P, V, Cr, Mn; L = OH, F, Cl, Br, I) have been studied by high-temperature X-ray diffraction and differential thermal analysis. Polymorphic transition nature was explained on the basis of the structure data. Connection between thermal stability and peculiarities of thermal expansion, which were explained in assumption of composition and structure of apatites was ascertained.

  18. Thermal conductivity of the gadolinium calcium silicate apatites: Effect of different point defect types

    International Nuclear Information System (INIS)

    The apatite crystal structure of the gadolinium calcium silicates can accommodate a wide range of point defects, including oxygen and cation vacancies, as well as anti-site defects, depending on the Gd/Ca ratio. Compositions having only cation or oxygen vacancies were identified and the thermal diffusivity and conductivity were measured up to 1000 deg. C. All the compositions, including the stoichiometric composition, exhibit low thermal conductivities from room temperature to high temperature with the defect-containing compositions having even lower thermal conductivities. The high-temperature thermal conductivity, at temperatures below the onset of significant radiative heat transport, decreases with the inverse square root of the cation and anion vacancy concentration, consistent with simple defect scattering models. Based on the data, it is concluded that the oxygen vacancies are slightly more effective in reducing thermal conductivity.

  19. Fluids in the Siilinjärvi carbonatite complex, eastern Finland: Fluid inclusion evidence for the formation conditions of zircon and apatite

    Directory of Open Access Journals (Sweden)

    Poutiainen, M.

    1995-06-01

    Full Text Available In the studied zircon and apatite crystals, data recorded two different compositional types of fluid inclusions: Type 1 H2O-CO2, low salinity inclusions (XCO2 = 0.42 to 0.87; XNaCl = 0.001 to 0.005 with bulk densities of 0.73 to 0.87 g/cm3, and Type 2 H2O moderate salinity (XNaCl = 0.03 to 0.06 inclusions with densities of 0.83 to 1.02 g/cm3. The Type 1 inclusions are not present in apatite. In zircon, the observed fluid inclusion types occur in separate domains: around (Type 1 and outside (Type 2 the apparent core. Fluid inclusions are further subdivided into pseudosecondary and secondary inclusions. Using a combination of SEM-EDS, optical characteristics and crushing-stage, various daughter and captive minerals were identified. The fluid inclusion data suggest that the pseudosecondary Type 1 and Type 2 inclusions in zircon and apatite were trapped during the pre-emplacement evolution of the carbonatite at mid-crustal conditions (P≥4 kbar, T≥625°C. The Type 1 fluid was depleted in CO2, during crystal fractionation and cooling leading to a fluid phase enriched in water and alkalies. Fenitization was obviously induced by these saline aqueous fluids. During emplacement of the carbonatite to the present level, zircon phenocrysts were intensively fractured, some Type 1 inclusions were re-equilibrated, and multiphase Type 2 inclusions were trapped. It is assumed that all these inclusions in zircon and the pseudosecondary Type 2 inclusions in apatite have a magmatic origin. In apatite, calcite inclusions occur side-by-side with the secondary Type 2 inclusions. These calcites co-existed with the aqueous fluid during fracturing and metamorphic re-crystallization of apatites. Probably, this metamorphic fluid also is responsible for the transport and deposition of at least some of the calcite at low temperatures (200-350°C.

  20. Vacuum-sintered body of a novel apatite for artificial bone

    Science.gov (United States)

    Tamura, Kenichi; Fujita, Tatsushi; Morisaki, Yuriko

    2013-12-01

    We produced regenerative artificial bone material and bone parts using vacuum-sintered bodies of a novel apatite called "Titanium medical apatite (TMA®)" for biomedical applications. TMA was formed by chemically connecting a Ti oxide molecule with the reactive [Ca10(PO4)6] group of Hydroxyapatite (HAp). The TMA powders were kneaded with distilled water, and solid cylinders of compacted TMA were made by compression molding at 10 MPa using a stainless-steel vessel. The TMA compacts were dried and then sintered in vacuum (about 10-3 Pa) or in air using a resistance heating furnace in the temperature range 1073-1773 K. TMA compacts were sintered at temperatures greater than 1073 K, thus resulting in recrystallization. The TMA compact bodies sintered in the range 1273-1773 K were converted into mixtures composed of three crystalline materials: α-TCP (tricalcium phosphate), β-TCP, and Perovskite-CaTiO3. The Perovskite crystals were stable and hard. In vacuum-sintering, the Perovskite crystals were transformed into fibers (approximately 1 µm in diameter × 8 µm in length), and the fiber distribution was uniform in various directions. We refer to the TMA vacuum-sintered bodies as a "reinforced composite material with Perovskite crystal fibers." However, in atmospheric sintering, the Perovskite crystals were of various sizes and were irregularly distributed as a result of the effect of oxygen. After sintering temperature at 1573 K, the following results were obtained: the obtained TMA vacuum-sintered bodies (1) were white, (2) had a density of approximately 2300 kg/m3 (corresponding to that of a compact bone or a tooth), and had a thermal conductivity of approximately 31.3 W/(m·K) (corresponding to those of metal or ceramic implants). Further, it was possible to cut the TMA bodies into various forms with a cutting machine. An implant made of TMA and inserted into a rabbit jaw bone was covered by new bone tissues after just one month because of the high

  1. Laser-SNMS analysis of apatite formation in vitro

    Science.gov (United States)

    Dambach, S.; Fartmann, M.; Kriegeskotte, C.; Brüning, C.; Wiesmann, H. P.; Lipinsky, D.; Arlinghaus, H. F.

    2004-06-01

    We have applied nonresonant laser secondary neutral mass spectrometry (Laser-SNMS) to examine different states of biomineralization in vitro. Primary osteoblast-like cells derived from bovine metacarpals were cultured for 5 weeks on clean smooth silicon substrates. For mass spectrometric investigations, the cells and newly formed mineral were cryofixed, freeze-fractured, and freeze-dried. The results indicate that in the vicinity of single osteoblasts, extracellular enrichment of potassium typically occurs during the initial stages of mineralization. Potassium may interact with matrix macromolecules and prevent an uncontrolled apatite deposition. However, apatite biomineral formation is correlated with a potassium release. In conclusion, potassium seems to be involved in the process of extracellular matrix biomineralization.

  2. Formation of Ultrafine Apatite Fibers by Sol-gel/Electrospinning

    Institute of Scientific and Technical Information of China (English)

    DING Ya-mei; YUAN Xiao-yan; ZHAO Jin; GUO Wan-chun; WANG Xiu-kui

    2007-01-01

    Ultrafine apatite fibers were prepared by electrospinning of sol-gel precursor/poly(vinyl pyrrolidone)(PVP) solutions followed by subsequent calcination. The as-electrospun and calcinated fibers were observed under a scanning electron microscope and an optical polarizing microscope. Results show that the morphology and the diameter of as-electrospun fibers strongly depend on the viscosity and the surface tension of sol-gel precursor/PVP solutions. After calcination, the smooth as-electrospun fibers shrink and the fiber diameter decreases because of the removal of the polymer. The chemical evolution upon the transformation of the precursor from a gel to the final apatite fibers was investigated by thermogravimetric-differential thermal analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. It is thus suggested that the crystalline structure of the calcined fibers is largely influenced by the calcination temperature. After being calcined at 600 ℃, the apatite fibers with a diameter of about 280 nm containing β-tricalcium phosphate were obtained.

  3. Structural studies of synthetic calcium and lead apatites

    International Nuclear Information System (INIS)

    Full text: Hydroxyapatite, Ca10(PO4)6(OH)2, is a major mineral component of calcified tissues, including bones and teeth. It is a good model system for natural apatites, having a structure which can easily accommodate a great variety of anionic and cationic substitutions. It acts as a natural sink for heavy metals, especially Pb and Cd, in biological systems. The hydroxyl ion can be replaced by other anions and one aim of the present work is to establish how such substitutions influence the ability of apatites to sequest and immobilise heavy metals. Environmentally speaking, there is still a lot of industrial use for Pb and the halide substituted apatite as lead chlorapatite, Pb10(PO4)6Cl2, which is found in Pb contaminated soils. This leads to interest in looking at the ability to release Pb encapsulated in mineral bodies and to develop methods that can selectively remove Pb from contaminated sites. We have used a combination of synchrotron X-ray diffraction and high resolution powder neutron diffraction methods for our structural studies of some substituted apatites. We have refined the structures of eight apatites M10(PO4)6X2, where M = Pb, Ca and X = OH, F, Cl, Br, using the Rietveld method. In these there are two cation sites, a channel of M-I atoms and a triangle of M-II atoms. The anion interacts most strongly with the M-II atoms at (↓, deg , 1/4). For the Ca compounds, the F ion sits within the triangles at (0, 0, 1/4), while the larger OH and Cl anions are disordered above and below the M-II triangles. The Br is at (0, 0, 1/2). Despite the larger size of the isostructural Pb compounds, no anions are found in the triangles. The F, Cl and Br ions are at (0, 0, 1/2) and the OH ion is disordered at (0, 0, z). This difference in behaviour is possibly related to the stereochemical activity of the Pb 6s electrons. While synchrotron X-ray methods have been important in determining the positional parameters of the heavy elements (eg. Pb, Ca), neutron scattering

  4. Apatite (U-Th)/He Date Dispersion Due to Secondary Grain Boundary Phases: An Example from the Henry Mountains, Utah

    Science.gov (United States)

    Murray, K. E.; Orme, D. A.; Reiners, P. W.

    2011-12-01

    Well-recognized (non-analytical) sources of variation in apatite (U-Th)/He dates include effects of variable: 1) radiation damage, 2) crystal size, and 3) parent zonation. The first two can be used advantageously to constrain thermal histories, and the third can often be characterized to recognize and quantify its effects. A more insidious and potentially widespread potential source of age dispersion, however, is U-Th located outside but within ~15-20 microns of dated apatites. Spiegel et al. (2009) documented the effects of He implantation from primary "bad-neighbour" grains. Secondary U-Th-bearing phases may have more complex effects. The effect of extragranular U-Th-bearing phases can make He dates too old or too young, depending on 1) when it forms, relative to the grain's cooling date, 2) whether it is recovered and analyzed with the grain, and 3) the relative U-Th content of the apatite and extragranular phase. Here we document the effects of external secondary phases on apatite He dates from samples from the Henry Mountains, Utah, where magmas intruded sedimentary rocks at 26-28 Ma. Detrital apatites from sedimentary rocks surrounding the laccoliths show positive date-eU correlations consistent with residence at ~1.5-km depths from ~27 to less than 5 Ma, when they were exhumed rapidly to near surface temperatures. Some apatite from igneous samples yield similar correlations, or uniform ~27 Ma ages regardless of eU, consistent with rapid cooling at this time. However, apatite from many igneous rocks show distinctive concave-up trends in date-eU plots. Grains with relatively high eU (~25-85 ppm) show positive date-eU correlations with maximum dates of ~27 Ma. But grains with low eU (~2-25 ppm) show inverse correlations that extend to dates as old as ~120 Ma. Many of the grains in these samples have extensive thin red-brown coatings that are likely mixtures of secondary clays and Fe-oxides. These coatings are easily removed by gentle physical abrasion, so it is

  5. 10 Towards a Safer Environment:(7)How apatite minerals remediate Pb, Zn and Mn from wastewater?

    Institute of Scientific and Technical Information of China (English)

    Samy Mohamed Abdallah

    2010-01-01

    To evaluate the effectiveness of apatite mineral in removing different contaminants from low quality water in the industrial city of abha,Asir region,southwestern of Saudi Arabia two phosphatic clay dominated by apatite mineral were selected.In situ remediation experiment proved that apatite mineral has the highest affinity for Pb and removed more than 94% from initial Pb concentration.The rest of contaminants followed the descending order of:Zn>Mn>Cu>Co>Ni.The sorption of Pb,Zn and Mn onto apatite mineral was well characterized by the Langmuir model.Ternary-metal addition induced competitive sorption among the three metals,with the interfering effect of Pb>Zn>Mn.Durlng metal retention by apatite mineral calcium and phosphate were determined in equilibrium solution.Calcium increased and phosphate decreased with increasing metal disappearance.The greatest increase of calcium and the largest phosphate reduction were found with Pb+2 sorption.This is suggested that Pb+2 retention by apatite was through the dissolution of apatite which mean release of Ca and P into solution and formation of pyromorphite(lead phosphate)as consuming of P.Obtained results suggested that there are two general mechanisms for the ability of apatite mineral to fake up Pb2+,Zn+2 and Mn+2.The first is(ion-ion exchange mechanism)concerned with adsorption of ions on the solid surface followed by their diffusion into apatite mineral and the release of cations originally contained within apatite.The second is(dissolution-precipitation mechanism)concerned to the dissolution of apatite in the aqueous solution containing Pb2+,Zn+2 and Mn+2 followed by the precipitation or coprecipitation.Pb+2 desorption responding to solution pH may indicate that not all the Pb+2 was chemisorbed and fraction of Pb+2 was weakly adsorbed or complexed on the surface of apatite mineral.

  6. Bioactive glasses with improved processing. Part 1. Thermal properties, ion release and apatite formation.

    Science.gov (United States)

    Groh, Daniel; Döhler, Franziska; Brauer, Delia S

    2014-10-01

    Bioactive glasses, particularly Bioglass® 45S5, have been used to clinically regenerate human bone since the mid-1980s; however, they show a strong tendency to undergo crystallization upon heat treatment, which limits their range of applications. Attempts at improving their processing (by reducing their tendency to crystallize) have included increasing their silica content (and thus their network connectivity), incorporating intermediate oxides or reducing their phosphate content, all of which reduce glass bioactivity. Therefore, bioactive glasses known for their good processing (e.g. 13-93) are considerably less bioactive. Here, we investigated if the processing of 45S5 bioactive glass can be improved while maintaining its network connectivity and phosphate content. The results show that, by increasing the calcium:alkali cation ratio, partially substituting potassium for sodium (thereby making use of the mixed alkali effect) and adding small amounts of fluoride, bioactive glasses can be obtained which have a larger processing window (suggesting that they can be processed more easily, allowing for sintering of scaffolds or drawing into fibres) while degrading readily and forming apatite in aqueous solution within a few hours. PMID:24880003

  7. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Visan, A. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Grossin, D. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Stefan, N.; Duta, L.; Miroiu, F.M. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Stan, G.E. [National Institute of Materials Physics, RO-077125, Magurele-Ilfov (Romania); Sopronyi, M.; Luculescu, C. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Freche, M.; Marsan, O.; Charvilat, C. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Ciuca, S. [Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania)

    2014-02-15

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ{sub FWHM} ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite.

  8. Molecular functionalization of tantalum oxide surface towards development of apatite growth

    International Nuclear Information System (INIS)

    We have studied the apatite growth dynamics on tantalum oxide surfaces. This nucleation is obtained via an organosilane intermediate layer between the apatite and the substrate surface. Four organosilane layers (differing by their terminal functionality) were investigated. Their characterization with atomic force microscopy and other techniques such as X-ray photoelectron spectroscopy (XPS) and wetting measurements highlighted the influence of the organosilane terminal groups on the apatite growth rates. Results revealed that apatite is indeed growing faster on phosphate terminal groups than on the three other groups studied (vinyl, hydroxyl and carboxyl).

  9. Characterization of antiseptic apatite powders prepared at biomimetics temperature and pH

    Directory of Open Access Journals (Sweden)

    Soumia Belouafa

    2008-03-01

    Full Text Available Antiseptic apatite-based calcium phosphates were prepared as the single-phase powders. Phosphocalcic oxygenated apatites were synthesized from calcium salts and orthophosphate dissolved in oxygenated water solution at 30%, under the biomimetic conditions of 37 °C and pH 7.4. The characterization and chemical analysis of the synthesized biomimetic apatite powders were performed by scanning electron microscopy (SEM, powder X ray diffraction (XRD, Fourier-transformed infrared spectroscopy (FT-IR and chemical analysis. The obtained materials are a calcium deficient apatites with different morphologies.

  10. Molecular functionalization of tantalum oxide surface towards development of apatite growth

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, D. [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Volcke, C. [Research Center in Physics of Matter and Radiation (PMR), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Arnould, Ch. [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Humbert, C.; Thiry, P.A. [Research Center in Physics of Matter and Radiation (PMR), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Delhalle, J. [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium); Mekhalif, Z., E-mail: zineb.mekhalif@fundp.ac.be [Laboratory of Chemistry and Electrochemistry of Surfaces (CES), University of Namur, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium)

    2009-02-15

    We have studied the apatite growth dynamics on tantalum oxide surfaces. This nucleation is obtained via an organosilane intermediate layer between the apatite and the substrate surface. Four organosilane layers (differing by their terminal functionality) were investigated. Their characterization with atomic force microscopy and other techniques such as X-ray photoelectron spectroscopy (XPS) and wetting measurements highlighted the influence of the organosilane terminal groups on the apatite growth rates. Results revealed that apatite is indeed growing faster on phosphate terminal groups than on the three other groups studied (vinyl, hydroxyl and carboxyl).

  11. Molecular functionalization of tantalum oxide surface towards development of apatite growth

    Science.gov (United States)

    Aubry, D.; Volcke, C.; Arnould, Ch.; Humbert, C.; Thiry, P. A.; Delhalle, J.; Mekhalif, Z.

    2009-02-01

    We have studied the apatite growth dynamics on tantalum oxide surfaces. This nucleation is obtained via an organosilane intermediate layer between the apatite and the substrate surface. Four organosilane layers (differing by their terminal functionality) were investigated. Their characterization with atomic force microscopy and other techniques such as X-ray photoelectron spectroscopy (XPS) and wetting measurements highlighted the influence of the organosilane terminal groups on the apatite growth rates. Results revealed that apatite is indeed growing faster on phosphate terminal groups than on the three other groups studied (vinyl, hydroxyl and carboxyl).

  12. In situ Sr isotope analysis of apatite by LA-MC-ICPMS: constraints on the evolution of ore fluids of the Yinachang Fe-Cu-REE deposit, Southwest China

    Science.gov (United States)

    Zhao, Xin-Fu; Zhou, Mei-Fu; Gao, Jian-Feng; Li, Xiao-Chun; Li, Jian-Wei

    2015-10-01

    Apatite is a ubiquitous accessory mineral in a variety of rocks and hydrothermal ores. Strontium isotopes of apatite are well known to retain petrogenetic information and have been widely used to investigate the origin of igneous rocks, but such attempts have rarely been made to constrain ore-forming processes of hydrothermal systems. We here report in situ LA-MC-ICPMS Sr isotope data of apatite from the ~1660-Ma Yinachang Fe-Cu-REE deposit, Southwest China. The formation of this deposit was coeval to the emplacement of regionally distributed doleritic intrusions within a continental-rift setting. The deposit has a paragenetic sequence consisting of sodic alteration (stage I), magnetite mineralization (stage II), Cu sulfide and REE mineralization (stage III), and final barren calcite veining (stage IV). The stage II and III assemblages contain abundant apatite, allowing to investigate the temporal evolution of the Sr isotopic composition of the ore fluids. Apatite of stage II (Apt II) is associated with fluorite, magnetite, and siderite, whereas apatite from stage III (Apt III) occurs intimately intergrown with ankerite and Cu sulfides. Apt II has 87Sr/86Sr ratios varying from 0.70377 to 0.71074, broadly compatible with the coeval doleritic intrusions (0.70592 to 0.70692), indicating that ore-forming fluids responsible for stage II magnetite mineralization were largely equilibrated with mantle-derived mafic rocks. In contrast, Apt III has distinctly higher 87Sr/86Sr ratios from 0.71021 to 0.72114, which are interpreted to reflect external radiogenic Sr, likely derived from the Paleoproterozoic strata. Some Apt III crystals have undergone extensive metasomatism indicated by abundant monazite inclusions. The metasomatized apatite has much higher 87Sr/86Sr ratios up to 0.73721, which is consistent with bulk-rock Rb-Sr isotope analyses of Cu ores with 87Sr/86Sri from 0.71906 to 0.74632. The elevated 87Sr/86Sr values of metasomatized apatite and bulk Cu ores indicate

  13. Thermal expansion of solid solutions in apatite binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Alexander V.; Bulanov, Evgeny N., E-mail: bulanoven@gmail.com; Korokin, Vitaly Zh.

    2015-01-15

    Graphical abstract: Thermal dependencies of volume thermal expansion parameter for with thermal expansion diagrams for Pb{sub 5}(PO{sub 4}){sub 3}F{sub x}Cl{sub 1−x}. - Highlights: • Solid solutions in three apatitic binary systems were investigated via HT-XRD. • Thermal expansion coefficients of solid solutions in the systems were calculated. • Features of the thermal deformation of the apatites were described. • Termoroentgenography is a sensitive method for the investigation of isomorphism. - Abstract: High-temperature insitu X-ray diffraction was used to investigate isomorphism and the thermal expansion of apatite-structured compounds in three binary systems in the entire temperature range of the existence of its hexagonal modifications. Most of the studied compounds are highly expandable (α{sub l} > 8 × 10{sup 6} (K{sup −1})). In Pb{sub 5}(PO{sub 4}){sub 3}F–Pb{sub 5}(PO{sub 4}){sub 3}Cl system, volume thermal expansion coefficient is independence from the composition at 573 K. In Pb{sub 5}(PO{sub 4}){sub 3}Cl–Pb{sub 5}(VO{sub 4}){sub 3}Cl, the compound with equimolar ratio of substituted atoms has constant volume thermal expansion coefficient in temperature range 298–973 K. Ca{sub 5}(PO{sub 4}){sub 3}Cl–Pb{sub 5}(PO{sub 4}){sub 3}Cl system is characterized by the most thermal sensitive composition, in which there is an equal ratio of isomorphic substituted atoms.

  14. Evaluation of apatite silicates as solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Martin-Sedeno, M.C.; Aranda, M.A.G. [Dpto. de Quimica Inorganica, Universidad Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C.; Nunez, P. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Ramos-Barrado, J.R. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain)

    2010-05-01

    Apatite-type silicates have been considered as promising electrolytes for Solid Oxide Fuel Cells (SOFC); however studies on the potential use of these materials in SOFC devices have received relatively little attention. The lanthanum silicate with composition La{sub 10}Si{sub 5.5}Al{sub 0.5}O{sub 26.75} has been evaluated as electrolyte with the electrode materials commonly used in SOFC, i.e. manganite, ferrite and cobaltite as cathode materials and NiO-CGO composite, chromium-manganite and Sr{sub 2}MgMoO{sub 6} as anode materials. Chemical compatibility, area-specific resistance and fuel cell studies have been performed. X-ray powder diffraction (XRPD) analysis did not reveal any trace of reaction products between the apatite electrolyte and most of the aforementioned electrode materials. However, the area-specific polarisation resistance (ASR) of these electrodes in contact with apatite electrolyte increased significantly with the sintering temperature, indicating reactivity at the electrolyte/electrode interface. On the other hand, the ASR values are significantly improved using a ceria buffer layer between the electrolyte and electrode materials to prevent reactivity. Maximum power densities of 195 and 65 mWcm{sup -2} were obtained at 850 and 700 C, respectively in H{sub 2} fuel, using an 1 mm-thick electrolyte, a NiO-Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} composite as anode and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} as cathode materials. This fuel cell was tested for 100 h in 5%H{sub 2}-Ar atmosphere showing stable performance. (author)

  15. Degassing pathways of Cl-, F-, H-, and S-bearing magmas near the lunar surface: Implications for the composition and Cl isotopic values of lunar apatite

    Science.gov (United States)

    Ustunisik, G. K.; Nekvasil, H.; Lindsley, D. H.; McCubbin, F. M.

    2015-12-01

    Experimental degassing of H-, F-, Cl-, C-, and S-bearing species from volatile-bearing magma of lunar composition at low P and fO2 close to quartz-iron-fayalite indicates that the composition of the fluid/vapor phase that is lost changes over time. A highly H-rich vapor phase is exsolved within the first 10 min. of degassing leaving behind a melt that is effectively dehydrated. Some Cl, F, and S is also lost during this time, presumably as HCl, HF, and H2S gaseous species; however much of the original inventory of Cl, F, and S components are retained in the melt. After 10 min., the exsolved vapor is dry and dominated by S- and halogen-bearing phases, presumably consisting of metal halides and sulfides, which evolves over time towards F enrichment. This vapor evolution provides important constraints on the geochemistry of volatile-bearing lunar phases that form subsequent to or during degassing. The rapidity of H loss suggests that little if any OH-bearing apatite will crystallize from surface or near surface (≈7m) melts and that degassing of lunar magmas will cause the compositions of apatites to evolve first towards the F-Cl apatite binary and eventually towards end member fluorapatite during crystallization. During the stage of loss of primarily H component from the melt, Cl would have been lost primarily as HCl, which is reported not to fractionate Cl isotopes at magmatic temperatures. After the loss of H-bearing species, continued loss of Cl would result in the degassing of metal chlorides, as a mechanism to fractionate Cl isotopes. After the onset of metal chloride degassing, the δ37Cl of the melt would increase to +6 (82% Cl loss), +8 (85% Cl loss), and +20‰ (95% Cl loss) at 1, 4, and 6 hours, respectively, approximated in a computed trajectory of δ37Cl values in basalt during degassing of FeCl2. This strong enrichment of 37Cl in the melt after metal chloride volatilization is fully consistent with values measured for the non-leachates of a variety of

  16. Study of Thermal Activated CO2 Extraction Processes from Carbonate Apatites Using Gas Chromatography

    Directory of Open Access Journals (Sweden)

    V.N. Kuznetsov

    2015-10-01

    Full Text Available The study of carbonate in the structure of carbonate-containing apatites (CCA is an actual problem due to the similarity of such systems to natural apatites of mammalian bone tissue. The search of the optimal synthesis procedures was also carried out in order to obtain carbonate apatites with the highest rate of carbonate ions incorporation into the apatite structure. The analysis of carbonate-group temperature behavior in apatites of various origin helps to understand their structural and functional roles in biologically relevant apatite materials. The thermal extraction and accumulation of CO2 from biogenic and geological apatites is also of interest for the further carbon isotope analysis with accelerating mass-spectrometry. X-ray diffraction analysis, infrared spectroscopy and scanning electron microscopy as well as self-proposed gas chromatography method with thermo-programmed probe extraction were used for carbonate temperature behavior study. This new method allows determining CO2 concentration released from CCA during annealing. The defined changes in carbonate apatite structure depending on synthesis procedure were observed.

  17. On the development of an apatitic calcium phosphate bone cement

    Indian Academy of Sciences (India)

    Manoj Komath; H K Varma; R Sivakumar

    2000-04-01

    Development of an apatitic calcium phosphate bone cement is reported. 100 Particles of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD) were mixed in equimolar ratio to form the cement powder. The wetting medium used was distilled water with Na2HPO4 as accelerator to manipulate the setting time. The cement powder, on wetting with the medium, formed a workable putty. The setting times of the putty were measured using a Vicat type apparatus and the compressive strength was determined with a Universal Testing Machine. The nature of the precipitated cement was analyzed through X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR) and energy dispersive electron microprobe (EDAX). The results showed the phase to be apatitic with a calcium–to–phosphorous ratio close to that of hydroxyapatite. The microstructure analysis using scanning electron microscopy (SEM) showed hydroxyapatite nanocrystallite growth over particulate matrix surface. The structure has an apparent porosity of ∼ 52%. There were no appreciable dimensional or thermal changes during setting. The cement passed the in vitro toxicological screening (cytotoxicity and haemolysis) tests. Optimization of the cement was done by manipulating the accelerator concentration so that the setting time, hardening time and the compressive strength had clinically relevant values.

  18. Lu-Hf isotope systematics of fossil biogenic apatite and their effects on geochronology

    Science.gov (United States)

    Herwartz, Daniel; Münker, Carsten; Tütken, Thomas; Hoffmann, J. Elis; Wittke, Andreas; Barbier, Bruno

    2013-01-01

    Reliable methods for direct dating of biogenic apatite from pre-Pleistocene fossils are currently not available, and recent attempts using the Lu-Hf decay system yielded highly inaccurate ages for both bones and teeth. The geological processes accounting for this poor accuracy of Lu-Hf chronometry are not yet understood. Here we explore Lu-Hf systematics in fossil bones and teeth in detail, by applying five different sample digestion techniques that are tested on bones and composites of bone and sediment. Our current dataset implies that dissolution methods only slightly affect the resulting Lu-Hf ages, while clear differences between the individual digestion techniques became apparent for element concentrations. By analysing the insoluble leftovers from incomplete sample dissolution, four main reservoirs of Hf in fossil bones were identified: (1) a radiogenic end-member associated with apatite; (2) an unradiogenic end-member represented by the authigenic minerals or the embedding sediment; (3) a highly unradiogenic end-member that can be attributed to detrital zircon; and (4) a moderately soluble phase (probably a Zr(Hf)-phosphate) that yielded very low Lu/Hf but a highly radiogenic Hf isotope composition at the same time. This Zr(Hf)-phase must have been precipitated within the fossil bone sample at a late stage of burial history, thereby incorporating radiogenic 176Hf released from apatite surfaces over geological timescales. A second focus of our study is the effect of different sediment matrices and of crystal size on the preservation of pristine Lu-Hf isotope compositions in bioapatite. Because near-depositional Lu-Hf ages of phosphate fossils have previously been reported for the London Clay (England) and a calcareous marl from Tendaguru (Tanzania), we herein investigate specimens fossilised in carbonate matrices (calcareous marl from Oker, Germany; carbonate concretions from the Santana Formation, Brazil; carbonate from the Eifel, Germany) and argillaceous

  19. Apatite precipitation on a novel fast-setting calcium silicate cement containing fluoride

    Science.gov (United States)

    Ranjkesh, Bahram; Chevallier, Jacques; Salehi, Hamideh; Cuisinier, Frédéric; Isidor, Flemming; Løvschall, Henrik

    2016-01-01

    Abstract Aim: Calcium silicate cements are widely used in endodontics. Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in teeth crowns including cavity lining and cementation. Objective: To evaluate the surface apatite-forming ability of Protooth compositions as a function of fluoride content and immersion time in phosphate-buffered saline (PBS). Material and methods: Three cement compositions were tested: Protooth (3.5% fluoride and 10% radiocontrast), ultrafast Protooth (3.5% fluoride and 20% radiocontrast), and high fluoride Protooth (15% fluoride and 25% radiocontrast). Powders were cap-mixed with liquid, filled to the molds and immersed in PBS. Scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy were used to characterize the precipitations morphology and composition after 1, 7, 28, and 56 days. Apatite/belite Raman peak height indicated the apatite thickness. Results: Spherical calcium phosphate precipitations with acicular crystallites were formed after 1-day immersion in PBS and Raman spectra disclosed the phosphate band at 965 cm−1, supporting the apatite formation over Protooth compositions. The apatite deposition continued and more voluminous precipitations were observed after 56 days over the surface of all cements. Raman bands suggested the formation of β-type carbonated apatite over Protooth compositions. High fluoride Protooth showed the most compact deposition with significantly higher apatite/belite ratio compared to Protooth and ultrafast Protooth after 28 and 56 days. Conclusions: Calcium phosphate precipitations (apatite) were formed over Protooth compositions after immersion in PBS with increasing apatite formation as a function of time. High fluoride Protooth exhibited thicker apatite deposition. PMID:27335901

  20. Influence of pentavalent niobium doping on microstructure and electrical conductivity of oxy-apatite La10Si6O27 electrolytes

    International Nuclear Information System (INIS)

    Oxy-apatite type La10Si6–xNbxO27+δ ceramics doped with different pentavalent niobium contents are synthesized via the high-temperature solid state reaction method. Crystal structure and electrical properties of La10Si6–xNbxO27+δ ceramics are investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectroscopy and complex impedance measurements. La10Si6O27 ceramic sintered at 1923 K consists of hexagonal oxy-apatite phase and a small amount of La2SiO5. Pentavalent niobium can partially substitute for tetravalent silicon to form a Nb-doped oxy-apatite structure. However, La2SiO5 phase disappears with increasing the pentavalent niobium content. Some fine La3NbO7 particles are found at grain boundaries of oxy-apatite phase in La10Si6–xNbxO27+δ ceramics when the pentavalent niobium content is beyond 0.1. Raman spectra of La10Si6–xNbxO27+δ ceramics generates three new characteristic modes at 710 cm−1, 342 cm−1 and 136 cm−1 with the addition of different pentavalent niobium contents, which are significantly enhanced especially at x = 0.1 and x = 0.5. These new modes are from Nb−O bonds of La3NbO7 phase and obstruct the interstitial oxide-ion O(5) from conducting in dry atmosphere, thus the grain boundary impedance of La10Si6–xNbxO27+δ ceramics increases correspondingly. La10Si5.9Nb0.1O27.05 ceramic exhibits the highest total conductivity among all the compositions above 873 K

  1. Production and in vitro characterization of 3D porous scaffolds made of magnesium carbonate apatite (MCA)/anionic collagen using a biomimetic approach

    Energy Technology Data Exchange (ETDEWEB)

    Sader, Marcia S., E-mail: msader@metalmat.ufrj.br [Prog. Engenharia Metalúrgica e Materiais, COPPE/UFRJ, RJ (Brazil); Martins, Virginia C.A. [Depto. de Química e Física Molecular, IQSC/USP, SP (Brazil); Gomez, Santiago [Dept. Anatomía Patológica, Universidad de Cádiz, Cadiz (Spain); LeGeros, Racquel Z. [Department of Biomaterials and Biomimetics, New York University College of Dentistry, NY (United States); Soares, Gloria A. [Prog. Engenharia Metalúrgica e Materiais, COPPE/UFRJ, RJ (Brazil)

    2013-10-15

    3D porous scaffolds are relevant biomaterials to bone engineering as they can be used as templates to tissue reconstruction. The aim of the present study was to produce and characterize in vitro 3D magnesium-carbonate apatite/collagen (MCA/col) scaffolds. They were prepared by using biomimetic approach, followed by cross-linking with 0.25% glutaraldehyde solution (GA) and liofilization. Results obtained with Fourier-transform infrared spectroscopy (FT-IR) confirmed the type-B carbonate substitution, while by X-ray diffraction (XRD), a crystallite size of ∼ 10 nm was obtained. Optical and electron microscopy showed that the cylindrical samples exhibited an open-porous morphology, with apatite nanocrystals precipitated on collagen fibrils. The cross-linked 3D scaffolds showed integrity when immersed in culture medium up to 14 days. Also, the immersion of such samples into an acid buffer solution, to mimic the osteoclastic resorption environment, promotes the release of important ions for bone repair, such as calcium, phosphorus and magnesium. Bone cells (SaOs2) adhered, and proliferated on the 3D composite scaffolds, showing that synthesis and the cross-linking processes did not induce cytotoxicity. Highlights: • 3D scaffolds of Mg-carbonate–apatite and anionic-collagen were produced. • The biomimetic approach and the cross-linking with 0.25% GA solution were employed. • The scaffolds showed open-porous structure and apatite crystals on collagen fibrils. • The cross-linked scaffolds exhibited integrity when immersed in culture medium. • SaOs2 cells adhered and proliferated on the cross-linked scaffolds confirming no cytotoxicity.

  2. Magnetic apatite for structural insights on the plasma membrane

    International Nuclear Information System (INIS)

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications. (paper)

  3. Biomimetic synthesis of calcium-strontium apatite hollow nanospheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this work,calcium-strontium apatite (Sr-HA) hollow nanospheres were synthesized by a facile biomimetic method.The structure and property of Sr-HA were characterized by FESEM,TEM,HRTEM,XRD and FT-IR spectroscopy.The influences of different ratios of calcium and strontium on the morphologies of the Sr-HA products were investigated.The experimental results revealed that the hollow spherical Sr-HA,with a size of 30-120 nm in diameter,could be synthesized when the molar ratio of Ca/Sr was 1:1.The possible formation mechanism of the hollow Sr-HA was proposed.The drug release experiments indicated that the hollow spherical Sr-HA had the property of sustained release.

  4. Stable isotope (C, O) and monovalent cation fractionation upon synthesis of carbonate-bearing hydroxyl apatite (CHAP) via calcite transformation

    Science.gov (United States)

    Böttcher, Michael E.; Schmiedinger, Iris; Wacker, Ulrike; Conrad, Anika C.; Grathoff, Georg; Schmidt, Burkhard; Bahlo, Rainer; Gehlken, Peer-L.; Fiebig, Jens

    2016-04-01

    Carbonate-bearing hydroxyl-apatite (CHAP) is of fundamental and applied interest to the (bio)geochemical, paleontological, medical and material science communities, since it forms the basic mineral phase in human and animal teeth and bones. In addition, it is found in non-biogenic phosphate deposits. The stable isotope and foreign element composition of biogenic CHAP is widely used to estimate the formation conditions. This requires careful experimental calibration under well-defined boundary conditions. Within the DFG project EXCALIBOR, synthesis of carbonate-bearing hydroxyapatite was conducted via the transformation of synthetic calcite powder in aqueous solution as a function of time, pH, and temperature using batch-type experiments. The aqueous solution was analyzed for the carbon isotope composition of dissolved inorganic carbonate (gas irmMS), the oxygen isotope composition of water (LCRDS), and the cationic composition. The solid was characterized by powder X-ray diffraction, micro Raman and FTIR spectroscopy, SEM-EDX, elemental analysis (EA, ICP-OES) and gas irmMS. Temperature was found to significantly impact the transformation rate of calcite to CHAP. Upon complete transformation, CHAP was found to contain up to 5% dwt carbonate, depending on the solution composition (e.g., pH), both incorporated on the A and B type position of the crystal lattice. The oxygen isotope fractionation between water and CHAP decreased with increasing temperature with a tentative slope shallower than those reported in the literature for apatite, calcite or aragonite. In addition, the presence of dissolved NH4+, K+ or Na+ in aqueous solution led to partial incorporation into the CHAP lattice. How these distortions of the crystal lattice may impact stable isotope discrimination is subject of future investigations.

  5. Biomimetic apatite-based composite materials obtained by spark plasma sintering (SPS): physicochemical and mechanical characterizations.

    Science.gov (United States)

    Brouillet, Fabien; Laurencin, Danielle; Grossin, David; Drouet, Christophe; Estournes, Claude; Chevallier, Geoffroy; Rey, Christian

    2015-08-01

    Nanocrystalline calcium phosphate apatites are biomimetic compounds analogous to bone mineral and are at the origin of the bioactivity of most biomaterials used as bone substitutes. Their unique surface reactivity originates from the presence of a hydrated layer containing labile ions (mostly divalent ones). So the setup of 3D biocompatible apatite-based bioceramics exhibiting a high reactivity requests the development of «low» temperature consolidation processes such as spark plasma sintering (SPS), in order to preserve the characteristics of the hydrated nanocrystals. However, mechanical performances may still need to be improved for such nanocrystalline apatite bioceramics, especially in view of load-bearing applications. The reinforcement by association with biopolymers represents an appealing approach, while preserving the advantageous biological properties of biomimetic apatites. Herein, we report the preparation of composites based on biomimetic apatite associated with various quantities of microcrystalline cellulose (MCC, 1-20 wt%), a natural fibrous polymer. The SPS-consolidated composites were analyzed from both physicochemical (X-ray diffraction, Fourier transform infrared, solid state NMR) and mechanical (Brazilian test) viewpoints. The preservation of the physicochemical characteristics of apatite and cellulose in the final material was observed. Mechanical properties of the composite materials were found to be directly related to the polymer/apatite ratios and a maximum crushing strength was reached for 10 wt% of MCC.

  6. Mineralogical and geochemical studies on apatites and phosphate host rocks of Esfordi deposit, Yazd province, to determine the origin and geological setting of the apatite

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Rajabzadeh

    2014-10-01

    Full Text Available Introduction Iron-apatite ore deposits well known as Kiruna iron type formed in association with calc-alkaline volcanism from Proterozoic to Tertiary (Hitzman et al., 1992. Liquid immiscibility in an igneous system was proposed to explain the formation of the iron oxides accompanying apatite in mineralized zones (Förster and Jafarzadeh, 1994; Daliran, 1999. The mode of ore formation however, is a matter in debate. Bafq region in Central Iran is one of the greatest iron mining regions in Iran with 750 million tons of reservoir. The majority of the iron deposits contains apatite as minor mineral and underwent metamorphism-alteration in varying degrees. The mode of formation and geological setting of Esfordi iron-apatite deposit in this region with an average of 13.9 wt% apatite are discussed using geochemical and mineralogical data along with field description. Materials and methods Fifty-three samples of mineralized zones and host rocks collected from 7 cross sections were studied by conventional microscopic methods. Seven representative samples were determined by XRD at Department of Physics, Shiraz University. Fifteen and six samples were also analyzed for major and trace elements using XRF at Binaloud Co. Iran, and ICP-MS at Labwest Minerals Analysis, Australia, respectively. Microprobe analyses were carried out on apatite in Geo Forschungs Zentrum Telegrafenberg at Potsdam University, Germany. Results Field observation shows that igneous host rocks in Esfordi were intensively altered by hydrothermal fluids. The ores are surrounded by wide altered halos. Petrographic investigation indicated that the most important alterations are of potassic, carbonatitic and silicification types. Magnetite and apatite occur as major minerals, accompanied by minor hematite and goethite in the mineralized zones. Rare Earth Element (REE minerals are present as minor phases in the ores. Three apatite mineralization types (vein, massive, and disseminated were

  7. Adsorption of nucleotides on biomimetic apatite: The case of adenosine 5‧ monophosphate (AMP)

    Science.gov (United States)

    Hammami, K.; Feki, H. El; Marsan, O.; Drouet, C.

    2015-10-01

    This work investigates the interaction between the nucleotide adenosine 5‧ monophosphate molecule (AMP) and a biomimetic nanocrystalline carbonated apatite as a model for bone mineral. The analogy of the apatite phase used in this work with biological apatite was first pointed out by complementary techniques. AMP adsorption isotherms were then investigated. Obtained data were fitted to a Sips isotherm with an exponent greater than one suggesting positive cooperativity among adsorbed molecules. The data were compared to a previous study relative to the adsorption of another nucleotide, cytidine monophosphate (CMP) onto a similar substrate, evidencing some effect of the chemical nature of the nucleic base. An enhanced adsorption was observed under acidic (pH 6) conditions as opposed to pH 7.4, which parallels the case of DNA adsorption on biomimetic apatite. An estimated standard Gibbs free energy associated to the adsorption process (ΔG°ads ≅ -22 kJ/mol) intermediate between "physisorption" and "chemisorption" was found. The analysis of the solids after adsorption pointed to the preservation of the main characteristics of the apatite substrate but shifts or enhancements of Raman bands attributed to AMP showed the existence of chemical interactions involving both the phosphate and adenine parts of AMP. This contribution adds to the works conducted in view of better understanding the interaction of DNA/RNA and their constitutive nucleotides and the surface of biomimetic apatites. It could prove helpful in disciplines such as bone diagenesis (DNA/apatite interface in aged bones) or nanomedicine (setup of DNA- or RNA-loaded apatite systems). Also, the adsorption of nucleic acids on minerals like apatites could have played a role in the preservation of such biomolecules in the varying conditions known to exist at the origin of life on Earth, underlining the importance of dedicated adsorption studies.

  8. Framework 'interstitial' oxygen in La{sub 10}(GeO{sub 4}){sub 5{sup -}}(GeO{sub 5})O{sub 2} apatite electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Pramana, S.S.; White, T.J. [Nanyang Technological Univ., Singapore (Singapore). School of Materials Science and Engineering; Klooster, W.T. [Nanyang Technological Univ., Singapore (Singapore). School of Materials Science and Engineering; Institute of Materials Research and Engineering, Singapore (Singapore)

    2007-08-15

    Oxygen conduction at low temperatures in apatites make these materials potentially useful as electrolytes in solid-oxide fuel cells, but our understanding of the defect structures enabling ion migration is incomplete. While conduction along [001] channels is dominant, considerable inter-tunnel mobility has been recognized. Using neutron powder diffraction of stoichiometric 'La{sub 10}(GeO{sub 4}){sub 6}O{sub 3}', it has been shown that this compound is more correctly described as an La{sub 10}(GeO{sub 4}){sub 5-}(GeO{sub 5})O{sub 2} apatite, in which high concentrations of interstitial oxygen reside within the channel walls. It is suggested that these framework interstitial O atoms provide a reservoir of ions that can migrate into the conducting channels of apatite, via a mechanism of inter-tunnel oxygen diffusion that transiently converts GeO{sub 4} tetrahedra to GeO{sub 5} distorted trigonal bipyramids. This structural modification is consistent with known crystal chemistry and may occur generally in oxide apatites. (orig.)

  9. Quantification of octacalcium phosphate, authigenic apatite and detrital apatite in coastal sediments using differential dissolution and standard addition

    Directory of Open Access Journals (Sweden)

    J. F. Oxmann

    2014-01-01

    Full Text Available Knowledge of calcium phosphate (Ca-P solubility is crucial for understanding temporal and spatial variations of phosphorus (P concentrations in water bodies and sedimentary reservoirs. In-situ relationships between liquid and solid-phase levels cannot be fully explained by dissolved analytes alone and need to be verified by determination of particular sediment P species. Lack of quantification methods for these species limits the knowledge of the P cycle. To address this issue, we (i optimized a specifically developed conversion-extraction (CONVEX method for P species quantification using standard additions; and (ii simultaneously determined solubilities of Ca-P standards by measuring their pH-dependent contents in the sediment matrix. Ca-P minerals including various carbonate fluorapatite (CFAP specimens from different localities, fluorapatite (FAP, fish bone apatite, synthetic hydroxylapatite (HAP and octacalcium phosphate (OCP were characterized by XRD, Raman, FTIR and elemental analysis. Sediment samples were incubated with and without these reference minerals and then sequentially extracted to quantify Ca-P species by their differential dissolution at pH values between 3 and 8. The quantification of solid-phase phosphates at varying pH revealed solubilities in the following order: OCP > HAP > CFAP (4.5% CO3 > CFAP (3.4% CO3 > CFAP (2.2% CO3 > FAP. Thus, CFAP was less soluble in sediment than HAP, and CFAP solubility increased with carbonate content. Unspiked sediment analyses together with standard addition analyses indicated consistent differential dissolution of natural sediment species vs. added reference species and therefore verified the applicability of the CONVEX method in separately determining the most prevalent Ca-P minerals. We found surprisingly high OCP contents in the analyzed coastal sediments which supports the hypothesis of apatite formation by an OCP precursor.

  10. Quantification of octacalcium phosphate, authigenic apatite and detrital apatite in coastal sediments using differential dissolution and standard addition

    Science.gov (United States)

    Oxmann, J. F.; Schwendenmann, L.

    2014-06-01

    Knowledge of calcium phosphate (Ca-P) solubility is crucial for understanding temporal and spatial variations of phosphorus (P) concentrations in water bodies and sedimentary reservoirs. In situ relationships between liquid- and solid-phase levels cannot be fully explained by dissolved analytes alone and need to be verified by determining particular sediment P species. Lack of quantification methods for these species limits the knowledge of the P cycle. To address this issue, we (i) optimized a specifically developed conversion-extraction (CONVEX) method for P species quantification using standard additions, and (ii) simultaneously determined solubilities of Ca-P standards by measuring their pH-dependent contents in the sediment matrix. Ca-P minerals including various carbonate fluorapatite (CFAP) specimens from different localities, fluorapatite (FAP), fish bone apatite, synthetic hydroxylapatite (HAP) and octacalcium phosphate (OCP) were characterized by XRD, Raman, FTIR and elemental analysis. Sediment samples were incubated with and without these reference minerals and then sequentially extracted to quantify Ca-P species by their differential dissolution at pH values between 3 and 8. The quantification of solid-phase phosphates at varying pH revealed solubilities in the following order: OCP > HAP > CFAP (4.5% CO3) > CFAP (3.4% CO3) > CFAP (2.2% CO3) > FAP. Thus, CFAP was less soluble in sediment than HAP, and CFAP solubility increased with carbonate content. Unspiked sediment analyses together with standard addition analyses indicated consistent differential dissolution of natural sediment species vs. added reference species and therefore verified the applicability of the CONVEX method in separately determining the most prevalent Ca-P minerals. We found surprisingly high OCP contents in the coastal sediments analyzed, which supports the hypothesis of apatite formation by an OCP precursor mechanism.

  11. Characterization by infrared spectrometry of chlorine and fluorine ions in apatites. Detection des ions chlore et fluor dans les apatites par spectrometrie infrarouge

    Energy Technology Data Exchange (ETDEWEB)

    Baumer, A. (Nice Univ., 06 (France)); Guilhot, B.; Gibert, R.; Vernay, A.M. (Ecole Nationale Superieure des Mines, 42 - Saint-Etienne (France)); Ohnenstetter, D. (Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France))

    1994-07-01

    Synthetic hydroxyapatites with low chlorine and fluorine contents have been prepared hydrothermally according to the reaction: Ca[sub 5] (PO[sub 4])[sub 3] OH + xNH[sub 4]Cl or + xNH[sub 4]F. The infrared spectra of these samples show that the 3,498 cm[sup -1] band of OH, CI apatites and 3,545 cm[sup -1] band of OH, F apatites make it possible to detect respectively 350 ppm of chlorine and 150 ppm of fluorine. A comparative infrared study of natural apatites confirms that the 3,485 and 3,480 cm[sup -1] bands must be attributed to the O-H...CI hydrogen bond. (authors). 3 tabs., 2 figs., 16 refs.

  12. U-Th-Pb Systematics in Zircon and Apatite from the Chicxulub Crater, Mexico

    Science.gov (United States)

    Kring, D. A.; Shaulis, B. J.; Schmieder, M.; Lapen, T. J.

    2016-08-01

    We probe the U-Th-Pb systematics in zircon and apatite to determine if post-impact hydrothermal activity produced discernible effects that are related to the duration, thermal evolution, and chemistry of the hydrothermal system.

  13. Preparation of Laminin-apatite-polymer Composites Using Metastable Calcium Phosphate Solutions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly ( ethylene terephthalate ) (PET) and polyethylene ( PE ) as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable ealcium phosphate solution supplemented with laminin ( LCP solution ). The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin- apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite composite coating.

  14. Geochemistry and genesis of apatite bearing Fe oxide Dizdaj deposit, SE Zanjan

    Directory of Open Access Journals (Sweden)

    Ghasem Nabatian

    2009-09-01

    Full Text Available Sorkheh-Dizaj apatite-iron oxide deposit is located 32 km southeast of Zanjan. The area is situated within the Tarom subzone of Western Alborz-Azarbaijan structural zone. The oldest units at the Sorkheh-Dizaj area are Eocene trachyte, trachyandesite, olivine basalt and volcanoclastic brecciate tuff and lapilli tuff which intruded by a quartz-monzonite, monzonite and granite subvolcanic pluton of Upper Eocene- Early Oligocene age. Subvolcanic plutonic rocks in the area show characteristics of the I-type granites. Magmatism of the area is of synorogenic to postorogenic related to magmatic arc environments. Mineralization at the area is divided into three main zones (A, B and C that all of which are located in the host subvolcanic pluton. These three zones are similar in terms of host rock, mineralogy, alteration, structure, texture and metal content. Mineralization in the volcanic rocks occurs as veins similar to those in three main zones, but less abundant. Geometry of the ore bodies is of vein type and their textures are stockwork, massive, banded, brecciate and vein-veinlet. The most important minerals at Sorkheh-Dizaj deposit are magnetite (low Ti and apatite that associated with them minor sulfide minerals such as chalcopyrite, bornite and pyrite. Minerals such as ilmenite, spinel (titanium magnetite, galena and sphalerite occur in low contents. The supergene minerals like chalcocite, malachite, azurite, covellite, hematite and goethite have been formed due to weathering and supergene processes. The main alterations at the deposit are K-feldspar metasomatism, actinolitization, argillic, sericitization, silicification, tourmalinization, and chlorite-epidotic. Rare earth elements (REE studies demonstrate that the deposit is more enriched in LREE than in HREE. The REE patterns in the apatite, magnetite and host rocks are similar suggesting a magmatic relationship. The REE contents of the apatites are higher than those of the host rocks and

  15. Fluoride enhances transfection activity of carbonate apatite by increasing cytoplasmic stability of plasmid DNA

    International Nuclear Information System (INIS)

    Highlights: → Cytoplasmic stability of plasmid DNA is enhanced by fluoride incorporation into carbonate apatite carrier. → Fluoridated carbonate apatite promotes a robust increase in transgene expression. → Controlled dissolution of fluoridated carbonate apatite in endosomal acidic environment might buffer the endosomes and prevent degradation of the released DNA. -- Abstract: Intracellular delivery of a functional gene or a nucleic acid sequence to specifically knockdown a harmful gene is a potential approach to precisely treat a critical human disease. The intensive efforts in the last few decades led to the development of a number of viral and non-viral synthetic vectors. However, an ideal delivery tool in terms of the safety and efficacy has yet to be established. Recently, we have developed pH-sensing inorganic nanocrystals of carbonate apatite for efficient and cell-targeted delivery of gene and gene-silencing RNA. Here we show that addition of very low level of fluoride to the particle-forming medium facilitates a robust increase in transgene expression following post-incubation of the particles with HeLa cells. Confocal microscopic observation and Southern blotting prove the cytoplasmic existence of plasmid DNA delivered by likely formed fluoridated carbonate apatite particles while degradation of plasmid DNA presumably by cytoplasmic nucleases was noticed following delivery with apatite particles alone. The beneficial role of fluoride in enhancing carbonate apatite-mediated gene expression might be due to the buffering potential of generated fluoridated apatite in endosomal acidic environment, thereby increasing the half-life of delivered plasmid DNA.

  16. Influence of Microstructure and Sintering Routes on Transport Properties of Apatite Materials for Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    A.Chesnaud; C.Estournes; G.Dezannau

    2007-01-01

    1 Results Oxy-apatite materials are thought as zirconia-substitutes in Solid Oxide Fuel Cells due to their fast ionic conduction. However, the well known difficulties related to their densification prevent them from being used as such. This study presents strategies to obtain oxy-apatite dense materials and the influence of elaboration route on transport properties. Particular emphasis is put on the microstructure effect on ion conduction. By the combined use of freeze-drying and conventional or spark p...

  17. Biomimetic coating of apatite/collagen composite on poly L-lactic acid facilitates cell seeding

    OpenAIRE

    Chen, Y; Mak, AFT; Wang, M; Li, J.

    2005-01-01

    Collagen and apatite were co-precipitated as a composite coating on poly L-lactic acid (PLLA) in an accelerated biomimetic process. The coating formed on PLLA films after 24 hours incubation was characterized. Saos-2 osteoblast-like cells were used to evaluate the cell seeding on this biomimetic composite coating. It was shown that cell seeding on PLLA films with the composite coating was greatly improved. PLLA coated with submicron collagen fibrils and submicron apatite paticulates can facil...

  18. Revisiting carbonate quantification in apatite (bio)minerals: a validated FTIR methodology

    OpenAIRE

    Grunenwald, Anne; Keyser, Christine; Sautereau, Anne-Marie; Crubézy, Eric; Ludes, Bertrand; Drouet, Christophe

    2014-01-01

    International audience Carbonated apatites represent an important class of compounds encountered in many fields including anthropology, archeology, geology, medicine and biomaterials engineering. They constitute, in particular, the mineral part of bones and teeth, are found in sedimentary settings, and are used as biomimetic compounds for the development of bone tissue engineering scaffolds. Whether for assessing the degree of biomimetism of synthetic apatites or for better understanding d...

  19. Electrical properties of iron doped apatite-type lanthanum silicates

    Institute of Scientific and Technical Information of China (English)

    SHI Qingle; ZHANG Hua

    2012-01-01

    The effect of Fe doping on the electrical properties of lanthanum silicates was investigated.The apatite-type lanthanum silicates La10Si6-xFexO27-x/2 (x=0.2,0.4,0.6,0.8,1.0) were synthesized via sol-gel process.The unit cell volume increased with Fe doping because the ionic radius of Fe3+ ion is larger than that of Si4+ ion.The conductivities of La10Si6-xFexO27 x/2 first increased and then decreased with the increasing of Fe content.The increase of the conductivity might be attributed to the distortion of the cell lattice,which assisted the migration of the interstitial oxygen ions.The decrease of the conductivity might be caused by the lower concentration of interstitial oxygen ions.The optimum Fe doping content in lanthanum silicates was 0.6.La10Si5.4Fe0.6O26.7 exhibited the highest ionic conductivity of 2.712× 10-2 S/cm at 800 ℃.The dependence of conductivity on oxygen partial pressure p(O2) suggested that the conductivity of La10Si6-xFexO27-x/2 was mainly contributed by ionic conductivity.

  20. Lanthanum germanate-based apatites as electrolyte for SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D.; Diaz-Carrasco, P.; Ramos-Barrado, J.R. [Departamento de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C. [Departamento de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain)

    2011-02-15

    Germanate apatites with composition La{sub 10-x}Ge{sub 5.5}Al{sub 0.5}O{sub 26.75-3x/2} have been evaluated for the first time as possible electrolytes for solid oxide fuel cells (SOFCs). Different electrode materials have been considered in this study, i.e. manganite, ferrite, nickelates and cobaltite as cathode materials; and NiO-CGO composite and chromium-manganite as anodes. The chemical compatibility and electrochemical performance of these electrodes with La{sub 9.8}Ge{sub 5.5}Al{sub 0.5}O{sub 26.45} have been studied by X-ray powder diffraction (XRPD) and impedance spectroscopy. The XRPD analysis did not reveal appreciable bulk reactivity with the formation of reaction products between the germanate electrolyte and these electrodes up to 1,200 C. However, a significant cation interdiffusion was observed by energy dispersive spectroscopy (EDS) at the electrode/electrolyte interface, which leads to a significant decrease of the performance of these electrodes. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Genesis of iron-apatite ores in Posht-e-Badam Block (central Iran) using REE geochemistry

    Indian Academy of Sciences (India)

    Mir Ali Asghar Mokhtari; Ghader Hossein Zadeh; Mohamad Hashem Emami

    2013-06-01

    Rare earth elements in apatites of different ore types show characteristic patterns which are related to different modes of formation of the ores. Most of the apatite-bearing iron ores are associated with alkaline magmas with LREE/HREE fractionation varying from moderate to steep. Iron-apatite deposits in Posht-e-Badam Block (Central Iran) have a high concentration of REE (more than 1000 ppm up to 2.5%), and show a strong LREE/HREE ratio with a pronounced negative Eu anomaly. This REE pattern is typical of magmatic apatite and quiet distinct from sedimentary apatites (phosphorites) which have a low REE contents and Ce negative anomalies. On the other hand, they are comparable to the REE patterns of apatites in Kiruna-type iron ores in different parts of the world. The REE patterns of apatites, iron-apatite ores and iron ores are similar and only have different REE contents. This similarity indicates a genetic relation for these rocks. Most of the iron-apatite deposits in Central Iran have similar REE patterns too, which in turn show a genetic relation for all of these deposits. This similarity indicates a similar origin and processes in their genesis. There are some small intrusions around some of the iron-apatite deposits that are petrographically identified as syenite and gabbro. These intrusions also have REE patterns similar to that of iron-apatite ores. This demonstrates a genetic relation between these intrusions and iron-apatite ores. The REE patterns of apatites in different deposits of Posht-e-Badam Block iron-apatite ores show an affinity to alkaline to sub-alkaline magmas and rifting environment. The alkaline host rocks of Central Iran iron-apatite ores are clearly related to an extensional setting where rifting was important (SSE–NNW fault lines). A probable source for this large scale ore forming processes is relatively low partial melting of mantle rocks. The ores have originated by magmatic differentiation as a late phase in the volcanic cycle

  2. Synthesis of sodium caseinate-calcium carbonate microspheres and their mineralization to bone-like apatite

    Science.gov (United States)

    Xu, Zhewu; Liang, Guobin; Jin, Lin; Wang, Zhenling; Xing, Chao; Jiange, Qing; Zhang, Zhiguang

    2014-06-01

    Phosphoproteins can induce and stabilize calcium carbonate (CaCO3) vaterite, which has desirable features for high reactivity. The purpose of this study was to synthesize bioactive CaCO3 microspheres for bone regeneration. Sodium caseinate (NaCas)-containing CaCO3 microspheres, with the crystal phase of vaterite, were synthesized by fast precipitation in an aqueous solution of CaCl2, Na2CO3, and 2 mg/mL of NaCas. The uniform microspheres exhibited rougher surfaces and lower negative charges than CaCO3 particles without NaCas addition. Fourier-transform infrared spectroscopy (FT-IR) of the microspheres showed characteristic peaks or bands corresponding to phosphate and hydroxyl groups. Thermogravimetric analysis (TGA) curves exhibited approximately 5% weight loss below 600 °C due to the decomposition of NaCas. Scanning electron microscope (SEM) images showed lath-like hydroxyapatite (HAp) on the surface after soaking in simulated body fluid (SBF) at 37 °C for 5 and 10 days. Energy dispersive X-ray spectrometry (EDS) revealed that the agglomerates were composed of Ca, C, O, P, Na, and Mg elements, and the Ca/P ratios ranged from 1.53 to 1.56. X-ray diffraction (XRD) patterns exhibited peaks characteristic of hydroxyapatite. The results of this study demonstrated that the addition of NaCas induced the formation of vaterite microspheres which possesses an enhanced apatite formation after soaking in SBF at 37 °C for 5 and 10 days. These NaCas-CaCO3 microspheres may be a potential biomaterial for bone regeneration.

  3. Strontium isotope systematics of scheelite and apatite from the Felbertal tungsten deposit, Austria - results of in-situ LA-MC-ICP-MS analysis

    Science.gov (United States)

    Kozlik, Michael; Gerdes, Axel; Raith, Johann G.

    2016-02-01

    The in-situ Sr isotopic systematics of scheelite and apatite from the Felbertal W deposit and a few regional Variscan orthogneisses ("Zentralgneise") have been determined by LA-MC-ICP-MS. The 87Sr/86Sr ratios of scheelite and apatite from the deposit are highly radiogenic and remarkably scattering. In the early magmatic-hydrothermal scheelite generations (Scheelite 1 and 2) the 87Sr/86Sr ratios range from 0.72078 to 0.76417 and from 0.70724 to 0.76832, respectively. Metamorphic Scheelite 3, formed by recrystallisation and local mobilisation of older scheelite, is characterised by even higher 87Sr/86Sr values between 0.74331 and 0.80689. Statistics allows discriminating the three scheelite generations although there is considerable overlap between Scheelite 1 and 2; they could be mixtures of the same isotopic reservoirs. The heterogeneous and scattering 87Sr/86Sr ratios of the two primary scheelite generations suggest modification of the Sr isotope system due to fluid-rock interaction and isotopic disequilibrium. Incongruent release of 87Sr from micas in the Early Palaeozoic host rocks of the Habach Complex contributed to the solute budget of the hydrothermal fluids and may explain the radiogenic Sr isotope signature of scheelite. Spatially resolved analyses revealed isotopic disequilibrium even on a sub-mm scale within zoned Scheelite 2 crystals indicating scheelite growth in an isotopic dynamical hydrothermal system. Zoned apatite from the W mineralised Early Carboniferous K1-K3 orthogneiss in the western ore field yielded 87Sr/86Sr of 0.72044-0.74514 for the cores and 0.74535-0.77937 for the rims. Values of magmatic apatite cores from the K1-K3 orthogneiss are comparable to those of primary Scheelite 1; they are too radiogenic to be magmatic. The Sr isotopic composition of apatite cores was therefore equally modified during the hydrothermal mineralisation processes, therefore supporting the single-stage genetic model in which W mineralisation is associated with

  4. Seed selections for crystallization of calcium phosphate for phosphorus recovery

    Institute of Scientific and Technical Information of China (English)

    SONG Yong-hui; Dietfried DONNERT; Ute BERG; Peter G. WEIDLER; Rolf NUEESCH

    2007-01-01

    Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus (P). In order to select suitable seed for P recovery from wastewater, three seeds including Apatite (AP), Juraperle (JP) and phosphate-modified Juraperle (M-JP) were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.

  5. LA-ICP-MS U-Pb apatite dating of Lower Cretaceous rocks from teschenite-picrite association in the Silesian Unit (southern Poland

    Directory of Open Access Journals (Sweden)

    Szopa Krzysztof

    2014-08-01

    Full Text Available The main products of volcanic activity in the teschenite-picrite association (TPA are shallow, sub-volcanic intrusions, which predominate over extrusive volcanic rocks. They comprise a wide range of intrusive rocks which fall into two main groups: alkaline (teschenite, picrite, syenite, lamprophyre and subalkaline (dolerite. Previous 40Ar/39Ar and 40K/40Ar dating of these rocks in the Polish Outer Western Carpathians, performed on kaersutite, sub-silicic diopside, phlogopite/biotite as well as on whole rock samples has yielded Early Cretaceous ages. Fluorapatite crystals were dated by the U-Pb LA-ICP-MS method to obtain the age of selected magmatic rocks (teschenite, lamprophyre from the Cieszyn igneous province. Apatite-bearing samples from Boguszowice, Puńców and Lipowa yield U-Pb ages of 103± 20 Ma, 119.6 ± 3.2 Ma and 126.5 ± 8.8 Ma, respectively. The weighted average age for all three samples is 117.8 ± 7.3 Ma (MSWD = 2.7. The considerably smaller dispersion in the apatite ages compared to the published amphibole and biotite ages is probably caused by the U-Pb system in apatite being less susceptible to the effects of hydrothermal alternation than the 40Ar/39Ar or 40K/40Ar system in amphibole and/or biotite. Available data suggest that volcanic activity in the Silesian Basin took place from 128 to 103 Ma with the the main magmatic phase constrained to 128-120 Ma.

  6. Fabrication and apatite inducing ability of different porous titania structures by PEO treatment.

    Science.gov (United States)

    Rao, X; Chu, C L; Sun, Q; Zheng, Y Y

    2016-09-01

    Plasma electrolytic oxidation (PEO) was employed to grow different porous titania structures on Ti6Al4V alloy (TC4) substrate using various parameters. It was found that the PEO voltage and working frequency could affect the morphology, the pore size, the pore density, the thickness and the phase composition of titania structures. Thereafter, three typical porous titania structures with nanosize pores, microsize pores and microsize grooves were respectively selected to estimate their bioactivity using SBF immersion test. After soaking at different durations (3-28d), the surface morphology, the chemical composition as well as the phase structure of deposited apatite layers on porous titania were evaluated using SEM, EDS, and XRD. The formation of various biomimetic apatite layers indicated the different influence due to the characteristics of porous titania structures. The porous titania structure with nanosize pores could induce a fast apatite growth at the early immersion stage (~7d), while the one with microsize pores exhibited the best apatite inducing ability at long term immersion (~28d). Based on the experimental results, the formation mechanism of biomimetic apatite affected by the pore structure of titania was discussed as well. PMID:27207066

  7. Bio-inspired citrate functionalized apatite coating on rapid prototyped titanium scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Peng [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China); Lu, Fang [School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006 (China); Zhu, Wenjun [Department of Prosthodontics, Guanghua School of Stomatology, Guang Dong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Wang, Di [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China); Zhu, Xiaojing [Department of Prosthodontics, Guanghua School of Stomatology, Guang Dong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Tan, Guoxin, E-mail: tanguoxin@126.com [Institute of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Wang, Xiaolan [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China); Zhang, Yu; Li, Lihua [General Hospital of Guangzhou Military Command of PLA, Guangzhou 510010 (China); Ning, Chengyun, E-mail: imcyning@scut.edu.cn [National engineering research center for tissue restoration and reconstruction, South China University of Technology, Guangzhou 510641 (China)

    2014-09-15

    Highlights: • Designed and reproducible porous titanium scaffolds were produced. • Hydrophilic nanoporous film was built on scaffold. • Apatite coating was deposited on scaffold under the modulation of citrate ions. • Citrate ions could affect CO{sub 3}{sup 2−} incorporation in apatite coatings. - Abstract: Scaffold functionalized with appropriate osteogenic coatings can significantly improve implant-bone response. In this study, with designed model and optimized manufacture parameters, reproducible and precise titanium scaffolds were produced. Reconstructed three-dimensional image and sectional structure of the scaffold were examined by micro-computed tomography and relative software. Alkali treatment was carried out on these manufactured porous scaffolds to produce nanoporous hydrophilic film. After 6 days deposition in simulated body fluid (SBF) containing sodium citrate (SC-SBF), plate-like amorphous calcium phosphate (ACP) coating was deposited on scaffold surface. Ultrasonication tests qualitatively indicated an enhanced adhesion force of apatite coatings deposited in SC-SBF compared to that deposited in SBF. And the effect of citrate ions on the CO{sub 3}{sup 2−} incorporation rate in apatite coating was quantitatively examined by bending vibration of CO{sub 3}{sup 2−} at ∼874 cm{sup −1}. Results indicated the highest carbonate content was obtained at the citrate ion concentration of 6 × 10{sup −5} mol/L in SC-SBF. These three-dimensional porous titanium-apatite hybrid scaffolds are expected to find application in bone tissue regeneration.

  8. PNNL Apatite Investigation at 100-NR-2 Quality Assurance Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Fix, N. J.

    2009-04-02

    In 2004, the U.S. Department of Energy, Fluor Hanford, Inc., Pacific Northwest National Laboratory (PNNL), and the Washington Department of Ecology agreed that the long-term strategy for groundwater remediation at the 100-N Area would include apatite sequestration as the primary treatment, followed by a secondary treatment if necessary. Since then, the agencies have worked together to agree on which apatite sequestration technology has the greatest chance of reducing strontium-90 flux to the Columbia River. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by staff working on the PNNL Apatite Investigation at 100-NR-2 Project. The plan is designed to be used exclusively by project staff.

  9. Carbon isotopes in eclogite and apatite separate from Huangzhen and Shima in SE Dabie

    Institute of Scientific and Technical Information of China (English)

    李一良; 郑永飞; 龚冰; 傅斌

    2000-01-01

    The carbon isotope compositions of high- and ultrahigh-pressure eclogite and apatite separate from Huangzhen and Shima in SE Dabie Mountains were analyzed by EA-MS online technique. The δ13C values of the eclogites cover a wide range of -30.7‰ - +1.5‰, whereasthose of apatites only have a small range of -28.1‰- -21.0‰. Some of the eclogites with thehigh δ13C values suffered retrogressive alteration by CO2-bearing fluids. The low δ13C values of the apatites indicate that the eclogites contain surficial carbon of organic origin. It is concluded that protoliths of the eclogites were exposed to the surface of the Earth, and that the carbon-bearing fluid was depleted in 13C during the eclogite-facies metamorphism.

  10. Carbon isotopes in eclogite and apatite separate from Huangzhen and Shima in SE Dabie

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The carbon isotope compositions of high- and ultrahigh-pressure eclogite and apatite separate from Huangzhen and Shima in SE Dabie Mountains were analyzed by EA-MS online technique. The δ13C values of the eclogites cover a wide range of -30.7‰ - +1.5‰, whereas those of apatites only have a small range of -28.1‰--21.0‰. Some of the eclogites with the high δ13C values suffered retrogressive alteration by CO2-bearing fluids. The low δ13C values of the apatites indicate that the eclogites contain surficial carbon of organic origin. It is concluded that protoliths of the eclogites were exposed to the surface of the Earth, and that the carbon-bearing fluid was depleted in 13C during the eclogite-facies metamorphism.

  11. Preliminary Apatite Fission Track Thermochronology of Wrangel Island, Arctic Russia

    Science.gov (United States)

    Dumitru, T. A.; Miller, E. L.

    2010-12-01

    Wrangel Island is part of a regional structural high that forms the continuation of the offshore Herald Arch and Chukchi Platform of Alaska. It is flanked on the north by the deep North Chukchi Basin, which in addition to Paleozoic strata, is inferred to contain up to 12 km of Beaufortian and Brookian (Late Jurassic to Tertiary) sediments (Dinkelman et al., 2008). To the south, ~E-W trending faults bound the Longa Basin that separates Wrangel from mainland Chukotka. This basin lies along strike of the early Tertiary Hope Basin in the Alaskan offshore. Wrangel Island itself exposes a broad, doubly-plunging anticlinorium-like structure cored by Neoproterozoic basement and flanked by Paleozoic shelf successions and a thick section of Triassic turbidites, representing about 5-7 km of structural section. The structural geology of Wrangel Island has been interpreted to represent a north-vergent Mesozoic fold and thrust belt linked by seismic reflection to the Herald Arch and then to the Lisburne Hills and the Brooks Range foreland fold and thrust belt (e.g. Kos’ko et al., 1993). However, deformation differs considerably from typical foreland fold-thrust structures of the Brooks Range as it is penetrative, involves large strains, and occurred under greenschist facies metamorphic conditions. Parts of the sequence exhibit mylonitic fabrics. Apatite fission track thermochronology of rocks from Wrangel Island can establishes the age of cooling to temperatures below ~ 100° C, providing temporal constraints on the uplift and erosional history of rocks that form this regional structural high. We analyzed seven fission track samples from a 9-km long N-S transect along the Kishchnikov River, from Triassic strata on the southern flank of the anticlinal structure to Devonian(?)-Mississippian feldspathic grits, conglomerates, and underlying Neoproterozoic igneous basement rocks in its core. All samples yielded statistically indistinguishable fission track ages averaging about 95

  12. Zircon-apatite U-Pb geochronology, zircon Hf isotope composition and geochemistry of granite batholith in the northern Mexico: Implications for Tectonomagmatic evolution of southern Cordillera.

    Science.gov (United States)

    Mahar, M. A.; Goodell, P.

    2015-12-01

    We present the zircon-apatite U-Pb ages and zircon Hf isotope composition of the granite batholith exposed at the western boundary of Chihuahua. Granidiorite samples were analyzed from both, north and south of the Rio El Fuerte and Sinforosa Lineament. Based on previous studies, the WWN-EES trending Sinforosa Lineament is proposed as the manifestation of a terrane boundary between Seri in the north and Tahue terrane in the south. Zircon U-Pb data indicate that the magmatism spans a time period of 36 Ma from 89 to 53 Ma to the north of the Sinforosa Lineament while granodiorites in the south of the Sinforosa Lineament are dated at 59 Ma. The U-Pb apatite ages are variable in the north of the Sinforosa Lineament and range from 86-51 Ma. These apatite dates are 1-28 Ma younger than the corresponding zircon U-Pb crystallization ages. This indicates variable cooling rates and moderate to shallow emplacement. In contrast, in the south of the Sinforosa Lineament, the U-Pb apatite ages (64-59 Ma) are indistinguishable from the zircon U-Pb age (59 Ma), indicating rapid cooling and shallow emplacement. Zircon morphology and U-Pb dating revealed the absence of inherited component in the zircon ages, as no inheritance of any age has been observed. Most of the northwestern Mexico is underlain by Precambrian-Paleozoic-Jurassic basement. However, in the study area, U-Pb dating does not support the involvement of the older basement in generating the granite magmas. The weighted mean initial ɛHf (t) isotope composition of granodiorites on both sides of the Sinforosa Lineament varies from +2 to +5. However, Hf isotope composition in the south of the Sinforosa Lineament is more heterogeneous and relatively evolved with weighted Mean ɛHf (t) = +1.45. The Hf isotope composition is consistent with the previously reported near bulk silicate Sr-Nd isotope values. We suggest that the magmatic rocks in this region are not derived from melting of a felsic older crust beneath the batholith

  13. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Yao Zhiwen [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Tang Changyu [Department of Polymer Science and Materials, Sichuan University (China); Darvell, B.W. [Dental Materials Science, Faculty of Dentistry, University of Hong Kong (Hong Kong); Zhang Hualin; Pan Lingzhan; Liu Jingsong [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Chen Zhiqing, E-mail: yangj0710@gmail.com [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China)

    2009-07-30

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  14. Osteointegration of biomimetic apatite coating applied onto dense and porous metal implants in femurs of goats

    NARCIS (Netherlands)

    Barrere, F.; Valk, van der C.M.; Meijer, G.; Dalmeijer, R.A.J.; Groot, de K.; Layrolle, P.

    2003-01-01

    Biomimetic calcium phosphate (Ca-P) coatings were applied onto dense titanium alloy (Ti6Al4V) and porous tantalum (Ta) cylinders by immersion into simulated body fluid at 37 °C and then at 50 °C for 24 h. As a result, a homogeneous bone-like carbonated apatitic (BCA) coating, 30 m thick was deposite

  15. Adsorption of Pb(II) present in aqueous solution on calcium, strontium and barium hydroxy apatites

    International Nuclear Information System (INIS)

    Calcium, strontium and barium hydroxy apatites were successfully synthesized by chemical precipitation method, the obtained powders were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscopy (Sem), semi-quantitative elemental analysis (EDS), infrared spectroscopy (IR), and N2 physisorption studies, complementary to these analytical techniques, was determined the surface fractal dimension (Df), and the amount of surface active sites of the materials, in order to know application as ceramic for water remediation. The ability of Pb(II) ion adsorption present in aqueous solution on the hydroxy apatites synthesized by batch type experiments was studied as a function of contact time, concentration of the adsorbate and temperature. The maximum lead adsorption efficiencies obtained were 0.31, 0.32 and 0.26 mg/g for calcium, strontium and barium hydroxy apatites respectively, achieved an equilibrium time of 20 minutes in the three solid-liquid systems studied. Experimental data were adequately adjusted at the adsorption kinetic model pseudo-second order, for the three cases. Moreover, experimental data of the strontium and calcium hydroxy apatites were adjusted to the Langmuir adsorption isotherm, indicating that the adsorption was through a monolayer, whereas barium hydroxyapatite was adjusted to the Freundlich adsorption isotherm, indicating a multilayer adsorption. The thermodynamic parameters obtained during adsorption studies as a function of temperature showed physisorption, exothermic and spontaneous processes respectively. The results showed that the calcium hydroxyapatite, strontium and barium are an alternative for the Pb(II) ion adsorption present in wastewaters. (Author)

  16. Adsorption of nucleotides on biomimetic apatite: The case of adenosine 5‧ triphosphate (ATP)

    Science.gov (United States)

    Hammami, Khaled; El-Feki, Hafed; Marsan, Olivier; Drouet, Christophe

    2016-01-01

    ATP is a well-known energy supplier in cells. The idea to associate ATP to pharmaceutical formulations/biotechnological devices to promote cells activity by potentially modulating their microenvironment thus appears as an appealing novel approach. Since biomimetic nanocrystalline apatites have shown great promise for biomedical applications (bone regeneration, cells diagnostics/therapeutics, …), thanks to a high surface reactivity and an intrinsically high biocompatibility, the present contribution was aimed at exploring ATP/apatite interactions. ATP adsorption on a synthetic carbonated nanocrystalline apatite preliminarily characterized (by XRD, FTIR, Raman, TG-DTA and SEM-EDX) was investigated in detail, pointing out a good agreement with Sips isothermal features. Adsorption characteristics were compared to those previously obtained on monophosphate nucleotides (AMP, CMP), unveiling some specificities. ATP was found to adsorb effectively onto biomimetic apatite: despite smaller values of the affinity constant KS and the exponential factor m, larger adsorbed amounts were reached for ATP as compared to AMP for any given concentration in solution. m tissue engineering, intracellular drug delivery, …).

  17. Adsorption/desorption of Direct Yellow 28 on apatitic phosphate: Mechanism, kinetic and thermodynamic studies

    Directory of Open Access Journals (Sweden)

    H. El Boujaady

    2014-10-01

    Full Text Available In this study, the adsorption potential of apatitic tricalcium phosphate for the removal of Direct Yellow 28 (DY28 from aqueous solution has been investigated by using batch mode experiments. The effects of different parameters such as pH, adsorbent dosage, initial dye concentration, contact time, addition of ions and temperature have been studied to understand the adsorption behavior of the adsorbent under various conditions. The adsorbent has been characterized by pHzpc measurement, chemical analyses, FTIR, XRD and TEM. The Langmuir and Freundlich models are found to be the best to describe the equilibrium isotherm data, with a maximum monolayer adsorption capacity of 67.02 mg g−1. Thermodynamic parameters including the Gibbs free energy ΔG, enthalpy ΔH, and entropy ΔS have revealed that the adsorption of DY28 on the apatitic tricalcium phosphate is feasible, spontaneous and endothermic. Among the kinetic models tested for apatitic tricalcium phosphate, the pseudo-second-order model fits the kinetic data well. The introduction of orthophosphate ions in the medium causes a decrease of adsorption. The addition of Ca2+ ions favors the adsorption. The results of this study have demonstrated the effectiveness and feasibility of the apatitic tricalcium phosphate for the removal of DY28 from aqueous solution.

  18. Xe- and U-tracks in apatite and muscovite near the etching threshold

    Energy Technology Data Exchange (ETDEWEB)

    Wauschkuhn, Bastian, E-mail: wauschku@geo.tu-freiberg.de [Geologie, Technische Universität Bergakademie Freiberg (Germany); Jonckheere, Raymond [Geologie, Technische Universität Bergakademie Freiberg (Germany); Mineralogie en Petrologie, Geologie en Bodemkunde, Universiteit Gent (Belgium); Ratschbacher, Lothar [Geologie, Technische Universität Bergakademie Freiberg (Germany)

    2015-01-15

    Ion irradiation of a wedge-shaped Durango apatite backed by a mica detector allows investigating ion track ranges and etching properties at different points along the tracks. Transmission profiles obtained by irradiation with 2 × 10{sup 6} cm{sup −2} 11.1 MeV/amu {sup 132}Xe and 2 × 10{sup 6} cm{sup −2} 11.1 MeV/amu {sup 238}U parallel to the apatite c-axis correspond to ranges calculated with SRIM (Xe: 76.3 μm; U: 81.1 μm). However, the measured profiles show much greater etchable track-length variations than the calculated longitudinal straggles. The probable cause is that the length deficit exhibits significant variation from track to track. The measured length deficit in muscovite is in agreement with most existing data. In contrast, the length deficit in apatite appears to be close to zero, which is in conflict with all earlier estimates. This probably results from the etching properties of the apatite basal face, which permit surface-assisted sub-threshold etching of track sections in the nuclear stopping regime. These sections are not accessible from the opposite direction, i.e. by etching towards the endpoint of the tracks or in the direction of the ion beam. This conclusion is supported by the fact that linear dislocations are revealed in apatite basal faces and by the observation of imperfect etch pits that are separated from the etched ion track channel by a section that appears unetched under the microscope.

  19. Laser Ablation in situ (U-Th-Sm)/He and U-Pb Double-Dating of Apatite and Zircon: Techniques and Applications

    Science.gov (United States)

    McInnes, B.; Danišík, M.; Evans, N.; McDonald, B.; Becker, T.; Vermeesch, P.

    2015-12-01

    We present a new laser-based technique for rapid, quantitative and automated in situ microanalysis of U, Th, Sm, Pb and He for applications in geochronology, thermochronometry and geochemistry (Evans et al., 2015). This novel capability permits a detailed interrogation of the time-temperature history of rocks containing apatite, zircon and other accessory phases by providing both (U-Th-Sm)/He and U-Pb ages (+trace element analysis) on single crystals. In situ laser microanalysis offers several advantages over conventional bulk crystal methods in terms of safety, cost, productivity and spatial resolution. We developed and integrated a suite of analytical instruments including a 193 nm ArF excimer laser system (RESOlution M-50A-LR), a quadrupole ICP-MS (Agilent 7700s), an Alphachron helium mass spectrometry system and swappable flow-through and ultra-high vacuum analytical chambers. The analytical protocols include the following steps: mounting/polishing in PFA Teflon using methods similar to those adopted for fission track etching; laser He extraction and analysis using a 2 s ablation at 5 Hz and 2-3 J/cm2fluence; He pit volume measurement using atomic force microscopy, and U-Th-Sm-Pb (plus optional trace element) analysis using traditional laser ablation methods. The major analytical challenges for apatite include the low U, Th and He contents relative to zircon and the elevated common Pb content. On the other hand, apatite typically has less extreme and less complex zoning of parent isotopes (primarily U and Th). A freeware application has been developed for determining (U-Th-Sm)/He ages from the raw analytical data and Iolite software was used for U-Pb age and trace element determination. In situ double-dating has successfully replicated conventional U-Pb and (U-Th)/He age variations in xenocrystic zircon from the diamondiferous Ellendale lamproite pipe, Western Australia and increased zircon analytical throughput by a factor of 50 over conventional methods

  20. Apatite-forming ability of vinylphosphonic acid-based copolymer in simulated body fluid: effects of phosphate group content.

    Science.gov (United States)

    Hamai, Ryo; Shirosaki, Yuki; Miyazaki, Toshiki

    2016-10-01

    Phosphate groups on materials surfaces are known to contribute to apatite formation upon exposure of the materials in simulated body fluid and improved affinity of the materials for osteoblast-like cells. Typically, polymers containing phosphate groups are organic matrices consisting of apatite-polymer composites prepared by biomimetic process using simulated body fluid. Ca(2+) incorporation into the polymer accelerates apatite formation in simulated body fluid owing because of increase in the supersaturation degree, with respect to apatite in simulated body fluid, owing to Ca(2+) release from the polymer. However, the effects of phosphate content on the Ca(2+) release and apatite-forming abilities of copolymers in simulated body fluid are rather elusive. In this study, a phosphate-containing copolymer prepared from vinylphosphonic acid, 2-hydroxyethyl methacrylate, and triethylene glycol dimethacrylate was examined. The release of Ca(2+) in Tris-NaCl buffer and simulated body fluid increased as the additive amount of vinylphosphonic acid increased. However, apatite formation was suppressed as the phosphate groups content increased despite the enhanced release of Ca(2+) from the polymer. This phenomenon was reflected by changes in the surface zeta potential. Thus, it was concluded that the apatite-forming ability of vinylphosphonic acid-2-hydroxyethyl methacrylate-triethylene glycol dimethacrylate copolymer treated with CaCl2 solution was governed by surface state rather than Ca(2+) release in simulated body fluid. PMID:27585911

  1. Postmagmatic magnetite-apatite assemblage in mafic intrusions: a case study of dolerite at Olympic Dam, South Australia

    Science.gov (United States)

    Apukhtina, Olga B.; Kamenetsky, Vadim S.; Ehrig, Kathy; Kamenetsky, Maya B.; McPhie, Jocelyn; Maas, Roland; Meffre, Sebastien; Goemann, Karsten; Rodemann, Thomas; Cook, Nigel J.; Ciobanu, Cristiana L.

    2016-01-01

    An assemblage of magnetite and apatite is common worldwide in different ore deposit types, including disparate members of the iron-oxide copper-gold (IOCG) clan. The Kiruna-type iron oxide-apatite deposits, a subtype of the IOCG family, are recognized as economic targets as well. A wide range of competing genetic models exists for magnetite-apatite deposits, including magmatic, magmatic-hydrothermal, hydrothermal(-metasomatic), and sedimentary(-exhalative). The sources and mechanisms of transport and deposition of Fe and P remain highly debatable. This study reports petrographic and geochemical features of the magnetite-apatite-rich vein assemblages in the dolerite dykes of the Gairdner Dyke Swarm (~0.82 Ga) that intruded the Roxby Downs Granite (~0.59 Ga), the host of the supergiant Olympic Dam IOCG deposit. These symmetrical, only few mm narrow veins are prevalent in such dykes and comprise besides usually colloform magnetite and prismatic apatite also further minerals (e.g., calcite, quartz). The genetic relationships between the veins and host dolerite are implied based on alteration in the immediate vicinity (~4 mm) of the veins. In particular, Ti-magnetite-ilmenite is partially to completely transformed to titanite and magmatic apatite disappears. We conclude that the mafic dykes were a local source of Fe and P re-concentrated in the magnetite-apatite veins. Uranium-Pb ages for vein apatite and titanite associated with the vein in this case study suggest that alteration of the dolerite and healing of the fractures occurred shortly after dyke emplacement. We propose that in this particular case the origin of the magnetite-apatite assemblage is clearly related to hydrothermal alteration of the host mafic magmatic rocks.

  2. Reduction And Stabilization (Immobilization) Of Pertechnetate To An Immobile Reduced Technetium Species Using Tin(II) Apatite

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, J. B.

    2012-11-02

    Synthetic tin(II)apatite reduces pertechnetate from the mobile +7 to a non-mobile oxidation state and sequesters the technetium, preventing re-oxidization to mobile +7 state under acidic or oxygenated conditions. Previous work indicated technetium reacted Sn(II)apatite can achieve an ANSI leachability index of 12.8 in Cast Stone. An effect by pH is observed on the distribution coefficient, the highest distribution coefficient being l70,900 observed at pH levels of 2.5 to 10.2. The tin apatite was resistant to releasing technetium under test conditions.

  3. Stable isotope record of coexisting apatite and dolomite in Early Cambrian phosphorites, Meishucun section, South China

    Science.gov (United States)

    Wegwerth, Antje; Struck, Ulrich; Segl, Monika; Vennemann, Torsten W.; Gehlken, Peer-L.; Heubeck, Christoph; Böttcher, Michael E.

    2010-05-01

    The Precambrian-Cambrian transition forms one of the most dramatic time periods in Earth's history, as global changes in tectonics, climate and chemistry in the atmosphere and oceans favoured the worldwide Cambrian Radiation and a concomitant ecosphere revolution. This time interval is paralleled by the first appearance of the widespread giant phosphorites. The well-known Meishucun section (South China), a former candidate section for the Pc-C boundary, documents phosphorite genesis amongst a rapid biodiversification, immediately following the end of the Precambrian in a low-latitude, shallow-water carbonate shelf. This contribution aims to elucidate the relation between simultaneous phosphorite deposition and global environmental conditions at the Pc-C boundary by using stable carbon and oxygen isotope analyses. Accurate determinations of d13C and d18O values may allow conclusions about ancient ocean circulation, paleo-productivity, paleo-temperatures, and most prominently diagenetic processes. The investigated samples from the Meishucun section basically consist of apatite, dolomite, and quartz that may be further devided into a lower and upper phosphorite as well as an overlying dolostone intervall. Additionally, calcite and siderite occur as minor compounds in some samples. Bulk d13C values of the carbonate fraction correlate with dolomite abundance throughout the section ranging from -4 to 1 per mil. Furthermore, several horizons suggest a relation between d13C values and apatite content, implying lower d13C values in apatites compared to coexisting dolomite. A slight negative d13C excursion at the top of the lower phosphorite coincides with the first appearance of small shelly fossils. Corresponding bulk d18O values generally show a stratigraphic-upward trend towards lower values throughout the record with slightly higher values in dolomite-rich sections. This may either indicate a warming trend during deposition, an isotopic shift in sea water composition

  4. Two high terbium content apatites: Tb{sub 5}Si{sub 2}BO{sub 13} and Tb{sub 4.66}Si{sub 3}O{sub 13}

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Pengyun [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, R.K., E-mail: rkli@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-02-15

    Graphical abstract: Two terbium apatites Tb{sub 5}Si{sub 2}BO{sub 13} and Tb{sub 4.66}Si{sub 3}O{sub 13} may be promising magneto-optical materials due to their high terbium content. - Highlights: • Two terbium apatite Tb{sub 5}Si{sub 2}BO{sub 13} and Tb{sub 4.66}Si{sub 3}O{sub 13} crystals were grown by flux method. • Structures of both compounds were determined via single-crystal diffraction. • Both compounds show paramagnetic behaviours down to 2 K. • Both compounds may be promising magneto-optical materials due to high Tb{sup 3+} contents. - Abstract: Two high content terbium apatites, Tb{sub 5}Si{sub 2}BO{sub 13} and Tb{sub 4.66}Si{sub 3}O{sub 13}, have been successfully synthesized by sol-gel method and have been crystallized from high temperature flux. Their structures were identified by single crystal X-ray diffraction and were found to belong to the hexagonal system with space group P6{sub 3}/m and unit cell parameters of a = 9.2569(10) Å, c = 6.8297(12) Å and Z = 2 for Tb{sub 5}Si{sub 2}BO{sub 13} and a = 9.493(4) Å, c = 6.852(5) Å and Z = 2 for Tb{sub 4.66}Si{sub 3}O{sub 13}, respectively. The diffuse optical reflection spectra clearly indicate that the two crystals have good optical transparency in the range of 500-1500 nm. The paramagnetic behaviours of Tb{sub 5}Si{sub 2}BO{sub 13} and Tb{sub 4.66}Si{sub 3}O{sub 13} from 2 K to 300 K are confirmed by magnetic susceptibility measurements. In comparison with other known Tb containing magneto-optical (MO) glass and crystals, Tb{sub 5}Si{sub 2}BO{sub 13} and Tb{sub 4.66}Si{sub 3}O{sub 13} are found to be promising magneto-optical materials in the visible-near IR range due to the high Tb{sup 3+} concentrations in both compounds.

  5. LABORATORY REPORT ON THE REDUCTION AND STABILIZATION (IMMOBILIZATION) OF PERTECHNETATE TO TECHNETIUM DIOXIDE USING TIN(II)APATITE

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN JB; HAGERTY K; MOORE WP; RHODES RN; JOHNSON JM; MOORE RC

    2012-06-01

    This effort is part of the technetium management initiative and provides data for the handling and disposition of technetium. To that end, the objective of this effort was to challenge tin(II)apatite (Sn(II)apatite) against double-shell tank 241-AN-105 simulant spiked with pertechnetate (TcO{sub 4}{sup -}). The Sn(II)apatite used in this effort was synthesized on site using a recipe developed at and provided by Sandia National Laboratories; the synthesis provides a high quality product while requiring minimal laboratory effort. The Sn(II)apatite reduces pertechnetate from the mobile +7 oxidation state to the non-mobile +4 oxidation state. It also sequesters the technetium and does not allow for re-oxidization to the mo bile +7 state under acidic or oxygenated conditions within the tested period oftime (6 weeks). Previous work (RPP-RPT-39195, Assessment of Technetium Leachability in Cement-Stabilized Basin 43 Groundwater Brine) indicated that the Sn(II)apatite can achieve an ANSI leachability index in Cast Stone of 12.8. The technetium distribution coefficient for Sn(II)apatite exhibits a direct correlation with the pH of the contaminated media. Table A shows Sn(II)apatite distribution coefficients as a function of pH. The asterisked numbers indicate that the lower detection limit of the analytical instrument was used to calculate the distribution coefficient as the concentration of technetium left in solution was less than the detection limit. The loaded sample (200 mg of Sn(II)apatite loaded with O.311 mg of Tc-99) was subjected to different molarities of nitric acid to determine if the Sn(II)apatite would release the sequestered technetium. The acid was allowed to contact for 1 minute with gentle shaking ('1st wash'); the aqueous solution was then filtered, and the filtrate was analyzed for Tc-99. Table B shows the results ofthe nitric acid exposure. Another portion of acid was added, shaken for a minute, and filtered ('2nd wash'). The

  6. The Effect of Nano-apatite on the Expression of Telomerase Gene of Human Hepatocellular Carcinoma Cells

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To investigate the effect of nano- apatite on the expression of the telomerase gene of human hepatocellular carcinoma cell lines and further explore the mechanism of the nano-apatite inhibiting cancer cells. Using the hybridization in situ method to detect the expression of the telomerase gene of human hepatocellular carcinoma cells treated with the nano- apatite for 4 h at 37 ℃. The hybridization in situ showed that the cytoplasm of the positive cells was stained in nigger-brown. The positive cell rate of the control group was 88.49% , the cisplatin group was 25.6% , the nano-apatite group was 63.6% . The activity oftelomerase gene was both obviously declined comparing with the control group and the difference had significance (p < 0.05, p < 0.01 ). The nanoapatite obviously inhabit the expression of the telomerase gene of human hepatocellular carcinoma cells.

  7. The influence of unstable signals for electron spin resonance dosimetry with synthetic A-type carbonated apatite

    International Nuclear Information System (INIS)

    Synthetic A-type carbonated apatite prepared in reproducible conditions was irradiated at room temperature with 60Co gamma rays. The ESR spectrum is associated to axial CO2- and orthorhombic CO3- species. Radicals used as dose markers in biological apatites are long-lived paramagnetic species. The stability of the post-irradiation signal of A-type apatite was investigated for more than one year. Measurements showed variations in the spectra attributed to unstable CO3- species, which can be eliminated by thermal treatments at 100 deg. C for 24 h. The CO2-spectrum can be identified in samples irradiated up to 0.2 Gy. All results indicate that the A-type apatite is an appropriate materials for radiotherapy dosimetry. (author)

  8. Morphological and chemical characterisation of biomimetic bone like apatite formation on alkali treated Ti6Al4V titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Faure, J. [INSERM-ERM 0203, Laboratoire de Microscopie Electronique, 21, rue Clement Ader, 51685 Reims, Cedex 02 (France); Balamurugan, A., E-mail: abmurugan@yahoo.co.in [INSERM-ERM 0203, Laboratoire de Microscopie Electronique, 21, rue Clement Ader, 51685 Reims, Cedex 02 (France); Department of Ceramics and Glass Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Benhayoune, H. [INSERM-ERM 0203, Laboratoire de Microscopie Electronique, 21, rue Clement Ader, 51685 Reims, Cedex 02 (France); Torres, P. [Department of Ceramics and Glass Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Balossier, G. [INSERM-ERM 0203, Laboratoire de Microscopie Electronique, 21, rue Clement Ader, 51685 Reims, Cedex 02 (France); Ferreira, J.M.F. [Department of Ceramics and Glass Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal)

    2009-05-05

    The present study is an attempt to enhance the apatite-forming ability of titanium metal induced by the alkaline (NaOH) treatment. A cell free culture medium, acellular DMEM solution was utilised to develop bone-like apatite on alkali-treated titanium alloy surface. The main advantage of this process is the development of bone like apatite with essential trace elements on the metallic substrate by using the DMEM culture medium as a soaking medium. The formed apatite deposits were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS). The obtained results suggest that the method utilized in this work can be successfully applied to obtain deposition of uniform coatings of crystalline hydroxyapatite on alkali treated titanium substrates.

  9. Morphological and chemical characterisation of biomimetic bone like apatite formation on alkali treated Ti6Al4V titanium alloy

    International Nuclear Information System (INIS)

    The present study is an attempt to enhance the apatite-forming ability of titanium metal induced by the alkaline (NaOH) treatment. A cell free culture medium, acellular DMEM solution was utilised to develop bone-like apatite on alkali-treated titanium alloy surface. The main advantage of this process is the development of bone like apatite with essential trace elements on the metallic substrate by using the DMEM culture medium as a soaking medium. The formed apatite deposits were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS). The obtained results suggest that the method utilized in this work can be successfully applied to obtain deposition of uniform coatings of crystalline hydroxyapatite on alkali treated titanium substrates.

  10. In vivo apatite formation induced on titanium metal and its alloys by chemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kokubo, T.; Kim, H.M. [Kyoto Univ. (Japan). Dept. of Material Chemistry; Nishiguchi, S.; Nakamura, T. [Kyoto Univ. (Japan). Dept. of Orthopaedic Surgery

    2001-07-01

    NaOH and heat treatments form an amorphous sodium titanate layer with a graded structure on the surfaces of titanium metal and its alloys. These treatments give no adverse effect on mechanical properties of the metals. Thus treated metals form an apatite layer on their surfaces in the living body by taking the calcium and phosphate ions from the surrounding fluid. This apatite layer is tightly integrated to the metal substrates through a graded structure, and bonds to the living bone in a short period, because of its structure and composition analogous to those of the bone mineral. This kind of bioactive metals are believed to be useful as bone substitutes even under load bearing conditions such as hip joints and dental implants. (orig.)

  11. Phosphate-induced metal stabilization: Use of apatite and bone char for the removal of soluble radionuclides in authentic and simulated DOE groundwater

    International Nuclear Information System (INIS)

    The apatite group of minerals is a family of calcium phosphate phases. Apatite is the principal component of bone tissue, and it also occurs naturally as mineral deposits in the geosphere. Bone char is calcined (coked) animal bone, containing activated carbon as well as calcium phosphate mineral phases. Apatite IItrademark is a more reactive form of apatite, supplied by UFA Ventures, Inc., at a cost of approximately 1/4 that of commercial bone char. Apatite is shown to be effective for the removal of select heavy metal impurities in groundwater. Previous investigations have demonstrated that apatite is an effective medium for the stabilization of soluble lead, cadmium, and zinc from mine waste leachate by the formation of highly insoluble precipitate phases. The performance of bone char and apatite II are compared with other candidate sorption media (including granular activated carbon and anion exchange resin) for the removal of soluble uranyl ion in synthetic DOE Site groundwater supplemented with varying levels of interfering nitrate ion. Apatite II has a greater affinity for U(VI), especially in the presence of nitrate ion, as evidenced by a larger value for the conditional distribution coefficient (Kd) in batch test experiments. Contact of uranyl nitrate solution with apatite II is shown to produce highly insoluble mineral phases of the autunite group (calcium uranyl phosphate hydrates). Apatite II is also demonstrated to be moderately effective for the removal of soluble radioactive isotopes of strontium, but not cesium, when these ions are supplemented into authentic DOE Site groundwater

  12. Novel bioactive Fe-based metallic glasses with excellent apatite-forming ability.

    Science.gov (United States)

    Qin, Chunling; Hu, Qingfeng; Li, Yongyan; Wang, Zhifeng; Zhao, Weimin; Louzguine-Luzgin, Dmitri V; Inoue, Akihisa

    2016-12-01

    We demonstrate, for the first time, that the (Fe0.75B0.15Si0.1)100-xNbx (x=0, 1 and 3at.%) metallic glasses without toxic and allergic elements exhibit excellent apatite-forming ability in simulated body fluids (SBF), which is expected to be a new generation of biomaterials in stents and orthopedic implants. For the alloys without any surface treatment, spherical particles corresponding to octacalcium phosphate are spontaneously nucleated and precipitated throughout the alloy surface after immersion only for 1day, indicating that the present alloys possess an unusual high bioactivity. During the subsequent in-vitro immersion for 3days, SEM image reveals the typical 'cauliflower' morphology of bone-like hydroxyapatite (HA) with Ca/P ratio of 1.65. In addition, it is surprising to find that the in-vitro SBF immersion not only leads to the formation and growth of the apatite layer but also causes the progressive development of the underlying alloy substrate. Moreover, for the alloys immersed for 3 or 9days, the substrate alloy just beneath the apatite layer consists of a hierarchical nano/macro-porous structure through selective dissolution of the active components Fe and B in the surface. XPS analysis indicates that the apatite nucleation on the present alloys in SBF is attributed to the specific dissolution properties of the present alloys and the fast formation of Si-OH and Fe-OH or Nb-OH functional groups, followed by combination of these groups with Ca(2+) and phosphate ions. PMID:27612742

  13. Enhanced apatite formation on Ti metal heated in PO2-controlled nitrogen atmosphere.

    Science.gov (United States)

    Hashimoto, Masami; Hayashi, Kazumi; Kitaoka, Satoshi

    2013-10-01

    The oxynitridation of biomedical titanium metal under a precisely regulated oxygen partial pressure (PO2) of 10(-14)Pa in nitrogen atmosphere at 973 K for 1 h strongly enhanced apatite formation compared with that on Ti heated in air. The factors governing the high apatite-forming ability are discussed from the viewpoint of the surface properties of Ti heated under a PO2 of 10(-14)Pa in nitrogen atmosphere determined from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. Nitrogen (N)-doped TiO2 (interstitial N) was formed on pure Ti heated under a PO2 of 10(-14)Pa in nitrogen atmosphere at 973 K. The XPS O1s main peak shifted toward a lower binding energy upon heating under a PO2 of 10(-14)Pa. This shift may be due to the formation of oxygen vacancies. This Ti surface had a positive zeta potential of approximately 20 mV. According to time-of-flight secondary ion mass spectroscopy results, PO4(3-) ions were predominantly adsorbed on Ti soaked in simulated body fluid (SBF) after heat treatment, followed by calcium ions. It was concluded that the apatite formation kinetics can be described using the Avrami-Erofeev equation with an Avrami index of n=2, which implies the instantaneous nucleation of apatite on the surface of Ti soaked in SBF after heat treatment at 973 K under a PO2 of 10(-14)Pa. PMID:23910327

  14. An evaluation of the reactivity of synthetic and natural apatites in the presence of aqueous metals.

    Science.gov (United States)

    Dybowska, Agnieszka; Manning, David A C; Collins, Matthew J; Wess, Timothy; Woodgate, Stephen; Valsami-Jones, Eugenia

    2009-04-01

    Metal removal from contaminated effluents was examined following reaction with natural apatites of biological and geological origin or a synthetic hydroxylapatite (HAP). Mammalian meat and bone meal (MBM), a by-product from meat industry, was the biological apatite source. The effect of incineration on metal removal capacity of MBM and HAP was also examined. The reactivity of apatites for all tested metals (Pb, Cd, Cu and Zn) followed the general order: synthetic > biological > mineral. For all apatites tested, Pb was removed best and preferentially from multi-metal solutions. MBM and HAP (0.5 g solid) removed Pb completely from both highly concentrated single metal solutions (50 ml, 1000 mg/L Pb) and from multi-metal solutions (50 ml) with 100 mg/L each of Cd, Cu and Zn in addition to Pb. The incineration of MBM (725 degrees C and 850 degrees C) reduced significantly its capacity for removal of Zn (by 47%, from 56 mg/g to 9 mg/g) and Cd (by 38%, from 53 mg/g to 13 mg/g) in particular and to a lesser extent for Cu (by 14%, from 61 mg/g to 46 mg/g) while the removal of Pb was not affected (100 mg/g). The same pattern was observed for incinerated HAP. SEM and XRD analysis indicated that HAP reacted with the metals by precipitation of pure metal phosphates--Pb hydroxylapatite, Zn phosphate (hopeite), a Cd phosphate (identified only by ED-SEM) and Cu phosphate (libenthenite).

  15. The thermal history of the Bowen Basin: a comparison of apatite fission track analysis and vitrinite reflectance

    International Nuclear Information System (INIS)

    Vitrinite reflectance and apatite fission-track analysis (AFTA) are two techiques widely used to assess paleotemperatures of the order of 20-120 deg.C. in sedimentary basins. Whereas vitrinite reflectance is essentially a qualitative technique that gives an integrated measure of the entire thermal history, AFTA can reveal information on the variation of paleotemperatures through time because fission-tracks in apatite are continually produced throughout geological time. An apatite fission track study of the Upper Permian units of the Bowen Basin has offered the opportunity to compare the two paleotemperature indicators and place constraints on the timing of maximum paleotemperatures. The regional pattern of apatite fission-track ages closely coincides with the vitrinite reflectance indicating that maximum paleotemperatures have varied across the Basin with the central region of the Bowen Basin experiencing highest paleotemperatures. The reduction in apatite reflectance fission-track age with increasing reflectance represents the progressive annealing at temperatures around 60-120 deg. C. of those fission-tracks formed prior to the time of maximum temperatures. In those samples giving the youngest apatite fission-track ages all tacks were totally annealed at this time, and the fission-track age in these samples, in the range 90-120 Myr, indicate the time of cooling from the thermal maximum in the Early Cretaceous. 1 ref

  16. Isotopic evidence for trapped fissiogenic REE and nucleogenic Pu in apatite and Pb evolution at the Oklo natural reactor

    Science.gov (United States)

    Horie, Kenji; Hidaka, Hiroshi; Gauthier-Lafaye, François

    2004-01-01

    A part of the boundary layer of reactor zone 10 at the Oklo natural reactor shows a unique petrologic texture, which contains high-grade uraninite and massive apatite concretions. In order to study distribution behavior of fission products around the boundary between the reactor zone and the wall rock and to clarify the relation of migration mechanisms of fission products with geochemical factors, in-situ isotopic analyses of Nd, Sm, Gd, Pb and U in uraninite and apatite from the sample were performed by Sensitive High Resolution Ion Microprobe (SHRIMP). Sm and Gd isotopic ratios of uraninite and apatite show evidence of neutron irradiation with fluence between 4.4-6.8×10 19 n/cm 2. Judging from the isotopic anomalies of Nd and U, the apatite coexisting with the uraninite plays an important role in trapping fissiogenic LREE and nucleogenic 239Pu into the structure. Systematic Pb isotopic data from apatite, uraninite, galena and minium suggest the following chronological interpretations. The apatite formed 1.92±0.01 Ga ago and trapped fissiogenic light REE and nucleogenic 239Pu that migrated from the reactor during the criticality. The uraninite around the boundary between reactor and sandstone dissolved once 1.1˜1.2 Ga ago. Galena grains were formed by U-Pb mobilization in association with the intrusion of dolerite dyke 0.45˜0.83 Ga ago. Minium was derived from recent dissolution of galena under locally oxidizing conditions.

  17. Search for stable energy levels in materials exhibiting strong anomalous fading: The case of apatites

    Energy Technology Data Exchange (ETDEWEB)

    Polymeris, George S., E-mail: polymers@auth.gr [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, ‘Athena’—Research and Innovation Center in Information, Communication and Knowledge Technologies, Kimmeria University Campus, GR-67100 Xanthi (Greece); Solid State Physics Section, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Giannoulatou, Valeria; Sfampa, Ioanna K. [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Tsirliganis, Nestor C. [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, ‘Athena’—Research and Innovation Center in Information, Communication and Knowledge Technologies, Kimmeria University Campus, GR-67100 Xanthi (Greece); Kitis, George [Nuclear Physics Laboratory, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2014-09-15

    The thermally assisted OSL signal resulting from very deep traps was studied in the case of three fluorapatite samples, one chlorapatite as well as one collophanite cryptocrystalline carbonite phosphorite sample of various origins. Intense thermally assisted OSL signal was monitored while stimulating at 200 °C in all samples subjected to the present study, indicating the prevalence of the existence of these very deep traps. Anomalous fading effect is ubiquitous for all TL and OSL signals of all apatite samples subjected to the present study. The anomalous fading of the thermally assisted OSL signal arising from very deep traps is strongly differentiated from the anomalous fading of electron trap excited at temperatures below 500 °C. The thermally assisted OSL signal arising from very deep traps was found to clearly be more stable, showing much less anomalous fading over time. The possible implications of this finding in dating of both apatites and feldspars are also briefly discussed. - Highlights: • All apatite samples of the present study yield strong thermally assisted OSL (TA-OSL) signal. • In all cases, TA-OSL signal is much more stable compared to TL and conventional OSL, based on the corresponding anomalous fading rates. • This experimental feature could be extremely beneficial for luminescence dating.

  18. Biomimetic Deposition of Apatite on Surface Chemically Modified Porous NiTi Shapememory Alloy

    Science.gov (United States)

    Wu, S. L.; Liu, X. M.; Chung, C. Y.; Chu, Paul K.; Chan, Y. L.; Yeung, K. W. K.; Chu, C. L.

    Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50-800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H2O2 and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate (Na2TiO3) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants.

  19. Bioactivity of hydrothermal-electrochemically deposited apatite in vitro and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Ban, S.; Harada, A.; Hasegawa, J. [Aichi-Gakuin Univ., Nagoya (Japan). Dept. of Dental Material Science; Arimoto, N. [Aichi-Gakuin Univ., Nagoya (Japan). Dept. of Operative Dentistry; Maruno, S. [Nagoya Inst. of Tech. (Japan). Dept. of Electrical and Computer Engineering

    2001-07-01

    Hydroxyapatite needles were formed on pure titanium plates using the hydrothermal-electrochemical method in an autoclave with two electrodes. The current was kept at 12.5 mA/cm{sup 2} for 1 h in an electrolyte containing Ca and phosphate ions maintained at 100, 150, and 200 C. Titanium plates coated with the hydrothermal-electrochemically deposited apatite at 100 C showed the largest weight gain after immersion in a simulated body fluid at 37 C for 3-27 weeks. Furthermore, the specimens coated at 100 C showed the largest weight loss after immersion in 0.01N HCl solution for 1 - 16 hours. There were no significant differences in the pull-out bonding strength of titanium bars coated at 100, 150, and 200 C to rabbit femora after 3-week implantation. All the hydrothermal-electrochemically deposited apatite showed an excellent biocompatibility. The new bone grew into the boundary between titanium substrate and deposited apatite from the outer surface. At 3-week implantation, the boundary at 100 C was completely filled with the new bone whereas that at 200 C was not yet filled with it. (orig.)

  20. Study of nanobiomaterial hydroxyapatite in simulated body fluid: Formation and growth of apatite

    Energy Technology Data Exchange (ETDEWEB)

    Chavan, Pradnya N.; Bahir, Manjushri M.; Mene, Ravindra U.; Mahabole, Megha P. [School of Physical Sciences, SRTM University, Nanded 431606 (India); Khairnar, Rajendra S., E-mail: rk2kin@yahoo.co [School of Physical Sciences, SRTM University, Nanded 431606 (India)

    2010-04-15

    Hydroxyapatite (HAp) is main mineral component of hard tissues. It is widely used in biomedical applications due to its excellent bioactivity and biocompatibility. Nanosized HAp is synthesized by wet chemical process. The synthesized HAp is characterized by XRD, FTIR, AFM and SEM for structural, morphological and functional groups analysis. The Simulated Body Fluid (SBF) is prepared by using chlorides, carbonates, oxides, and sulphates of alkali metals at 37 deg. C. The ion exchange process is carried out to exchange calcium cation by sodium and potassium. The pure HAp and ion exchanged HAp pellets are used as source of nucleating agent for apatite layer formation, in SBF maintained at 37 deg. C using incubator for different periods of time to study the bioactivity. The dielectric study is carried out on incubated pure and ion exchanged HAp pellets. XRD analysis confirms the hexagonal phase of hydroxyapatite. FTIR shows the presence of functional groups. SEM observations reveal that the growth of highly porous apatite layer on HAp surface increases with time. The dielectric constant is found to be in the range 3-12. It is seen that the synthesized HAp bioceramic nano material not only supports the growth of apatite layer but also accelerates the growth onto itself.

  1. Effect of Apatite Nanoparticles on DNA and AgNOR of Bel-7402 Hepatocellular Carcinoma

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The effect of apatite nanoparticles on proliferation potential and biological behaviour of the human hepatocellular carcinoma in vitro were investigated. After the treatment of Bel- 7402 hepatocellular carcinoma cells with apatite nanoparticles at a concentration of 5 × 10-4 mmol/ L for 4days, Feulgen and AgNOR stain were conducted and the specimens were observed by microscope. The DNA and AgNOR were quantified with image analysis techniques. It was found that there was a significant decrease of the DNA content (58.62 ± 6.52) in the nanoparticles treated group compared to the control (78.21 ± 4.17). It was further found that there was a decrease in the number of AgNOR granules in the nanoparticle treated group (7.41 ± 1.02) compared to the control group (9.95± 0.28). The experimental results showed that apatite nanoparticles could decrease the DNA reproductive activity and the rRNA synthesis in Bel-7402 hepatocellular carcinoma cells.

  2. Formation of Porous Apatite Layer during In Vitro Study of Hydroxyapatite-AW Based Glass Composites

    Directory of Open Access Journals (Sweden)

    Pat Sooksaen

    2015-01-01

    Full Text Available This research discussed the fabrication, characterization, and in vitro study of composites based on the mixture of hydroxyapatite powder and apatite-wollastonite (AW based glass. AW based glass was prepared from the SiO2-CaO-MgO-P2O5-CaF2 glass system. This study focuses on the effect of composition and sintering temperature that influences the properties of these composites. Microstructural study revealed the formation of apatite layer on the composite surfaces when immersed in simulated body fluid (SBF solution at 37°C. Composites containing ≥50 wt% AW based glass showed good bioactivity after 7 days of immersion in the SBF. A porous calcium phosphate (potentially hydroxycarbonate apatite, HCA layer formed at the SBF-composite interface and the layer became denser at longer soaking period, for periods ranging from 7 to 28 days. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES analysis showed that early stage of soaking occurred with the release of Ca and Si ions from the composites and the decrease of P ions with slow exchange rate.

  3. In vivo bioactivity of titanium and fluorinated apatite coatings for orthopaedic implants: a vibrational study

    Science.gov (United States)

    Taddei, Paola; Tinti, Anna; Reggiani, Matteo; Monti, Patrizia; Fagnano, Concezio

    2003-06-01

    The bone integration of implants is a complex process which depends on chemical composition and surface morphology. To accelerate osteointegration, metal implants are coated with porous metal or apatites which have been reported to increase mineralisation, improving prosthesis fixation. To study the influence of composition and morphology on the in vivo bioactivity, titanium screws coated by Plasma Flame Spraying (PFS) with titanium or fluorinated apatite (K690) were implanted in sheep tibia and femur for 10 weeks and studied by micro-Raman and IR spectroscopy. The same techniques, together with thermogravimetry, were used for characterising the pre-coating K690 powder. Contrary to the manufacturer report, the K690 pre-coating revealed to be composed of a partially fluorinated apatite containing impurities of Ca(OH) 2 and CaCO 3. By effect of PFS, the impurities were decomposed and the crystallinity degree of the coating was found to decrease. The vibrational spectra recorded on the implanted screws revealed the presence of newly formed bone; for the K690-coated screws at least, a high level of osteointegration was evidenced.

  4. Combinatorial MAPLE deposition of antimicrobial orthopedic maps fabricated from chitosan and biomimetic apatite powders.

    Science.gov (United States)

    Visan, A; Stan, G E; Ristoscu, C; Popescu-Pelin, G; Sopronyi, M; Besleaga, C; Luculescu, C; Chifiriuc, M C; Hussien, M D; Marsan, O; Kergourlay, E; Grossin, D; Brouillet, F; Mihailescu, I N

    2016-09-10

    Chitosan/biomimetic apatite thin films were grown in mild conditions of temperature and pressure by Combinatorial Matrix-Assisted Pulsed Laser Evaporation on Ti, Si or glass substrates. Compositional gradients were obtained by simultaneous laser vaporization of the two distinct material targets. A KrF* excimer (λ=248nm, τFWHM=25ns) laser source was used in all experiments. The nature and surface composition of deposited materials and the spatial distribution of constituents were studied by SEM, EDS, AFM, GIXRD, FTIR, micro-Raman, and XPS. The antimicrobial efficiency of the chitosan/biomimetic apatite layers against Staphylococcus aureus and Escherichia coli strains was interrogated by viable cell count assay. The obtained thin films were XRD amorphous and exhibited a morphology characteristic to the laser deposited structures composed of nanometric round shaped grains. The surface roughness has progressively increased with chitosan concentration. FTIR, EDS and XPS analyses indicated that the composition of the BmAp-CHT C-MAPLE composite films gradually modified from pure apatite to chitosan. The bioevaluation tests indicated that S. aureus biofilm is more susceptible to the action of chitosan-rich areas of the films, whilst the E. coli biofilm proved more sensible to areas containing less chitosan. The best compromise should therefore go, in our opinion, to zones with intermediate-to-high chitosan concentration which can assure a large spectrum of antimicrobial protection concomitantly with a significant enhancement of osseointegration, favored by the presence of biomimetic hydroxyapatite. PMID:27418570

  5. A study of apatite formation on natural nano-hydroxyapatite/ chitosan composite in simulated body fluid

    Institute of Scientific and Technical Information of China (English)

    Yong-bin FAN; Xiao-ying L(U)

    2008-01-01

    This study is focused on the ability of apatite formation on the surface of nano-hydroxyapatite (HA)/chitosan (CH) composite in simulated body fluid (SBF) in vitro. At first, natural nano-HA was prepared according to a wet-bailing method and the composite was prepared by combining the natural nano-hydroxyapatite and chit-osan, and then in vitro biomineralization test of natural nano-HA/CH composite was carried out in standard SBF. Subsequently, the quantity of the weight of the particles formed on the composite surface in SBF was measured by analytical balance, and the morphology change on the surface of the composite was observed by a scanning elec-tron microscope (SEM). Lastly, a Fourier transform infrared spectroscope (FTIR) was used to investigate the chemical components of the particles formed on the nat-ural nano-HA/CH composite surface in SBF. The result of quantity assessment shows that the weight of the com-posite increased with the increase of soaking time. The SEM image shows that the particles were gradually formed on natural nano-HA/CH composite surface, and the FTIR spectrum of the particles on composite surface confirms that these particles were carbonate apatite. This study indicates that the nano-HA/CH composite has a good ability for apatite formation in SBF, which predicts the bone-inducing ability of natural nano-HA/CH com-posite in vivo.

  6. Nanocomposite Apatite-biopolymer Materials and Coatings for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    L.F. Sukhodub

    2014-04-01

    Full Text Available The microoverview paper describes synthesis and characterization of novel third generation composite biomaterials and coatings which correspond to the second structural level of human bone tissue (HBT organization obtained at Sumy state university “Bionanocomposite” laboratory. To obtain such composites an animal collagen is usually used, which is not potentially safe for medical applications. That is why investigations were started using some other biopolymers to obtain composites close to the second level in the structural hierarchy of HBT. Proposed natural polymers (Na alginate, chitosan are the most perspective because they have bacteriostatic properties for a vast number of aerobic and anaerobic bacteria, high biocompatibility towards the connective tissue, low toxicity, an ability to improve regenerative processes during wounds healing, degradation ability with the creation of chemotaxic activity towards fibroblasts and osteoblasts. The formation of nanosized (25-75 nm calcium deficient hydroxyapatite (cdHA particles in the polymer scaffold approaches the derived material to the biogenic bone tissue, which can provide its more effective implantation. The influence of the imposition of static magnetic field on brushite (CaHPO4·2H2O crystallization was also investigated. It was shown that changing the magnetic field configuration could greatly affect crystallinity and texture of the derived particles. To increase the biocompatibility of existing medical implants (Ti–6Al 4V, Ti Ni, Mg the technology for obtaining bioactive coatings with corresponding mechanical, structural and morphology characteristics is developed in our laboratory. In this direction coatings based on cdHA in combination with biopolymer matrices (Na alginate, chitosan, are obtained in “soft” conditions using a thermal substrate technology. This technology was proposed by Japan scientists [1] and was sufficiently improved by us [2] in order to obtain coatings in

  7. Ion microprobe U-Pb dating and strontium isotope analysis of biogenic apatite

    Science.gov (United States)

    Sano, Y.; Toyoshima, K.; Takahata, N.; Shirai, K.

    2012-12-01

    Conodonts are micro-fossils chemically composed of apatite which occurred in the body of one animal. They are guide fossils to show formation ages of sedimentary sequences with the highest resolution [1] and good samples to verify the dating method. We developed the ion microprobe U-Pb dating of apatite [2] and applied the method to a Carboniferous conodont [3] by using a SHRIMP II installed at Department of Earth and Planetary Sciences, Hiroshima University. Recently we have developed the NanoSIMS U-Pb dating method and successfully measured the formation ages of monazite [4] and zircon [5] at Atmosphere and Ocean Research Institute, University of Tokyo. In this work we carried out the NanoSIMS U-Pb dating of biogenic apatite such as conodont. Since the spot size of NanoSIMS is smaller than SHRIMP II, it is easier to have multi-spots on the single fragment of biogenic apatite. Based on the isochron method of U-Pb system, we have calculated the formation ages. They are consistent with those in literature. In order to study the chemical evolution of ocean during the past 600 Million years, strontium isotopes (87Sr/86Sr) of fossil marine carbonate such as coral skeletons and foraminifera tests were measured and compiled [6]. However they are not robust when the age is older than 500Ma, partly due to post-depositional histories. Apatite is more stable and more resistant to the alteration than carbonate [7]. Recently we have developed the method of NanoSIMS strontium isotopic analysis of a fish otolith, which composed of aragonite [8]. In this work we carried out the strontium isotopic analysis of biogenic apatite. The advantage of the ion microprobe technique over the TIMS (thermal ionization mass spectrometer) and MC-ICP-MS (multi-collector inductively coupled argon plasma mass spectrometer) method is preservation of the important textural context and to provide an opportunity for other simultaneous analytical work with high spatial resolution. This is the case for

  8. Biological Apatite Formed from Polyphosphate and Alkaline Phosphatase May Exchange Oxygen Isotopes from Water through Carbonate

    Science.gov (United States)

    Omelon, S. J.; Stanley, S. Y.; Gorelikov, I.; Matsuura, N.

    2011-12-01

    The oxygen isotopic composition in bone mineral phosphate is known to reflect the local water composition, environmental humidity, and diet1. Once ingested, biochemical processes presumably equilibrate PO43- with "body water" by the many biochemical reactions involving PO43- 2. Blake et al. demonstrated that enzymatic release of PO43- from organophosphorus compounds, and microbial metabolism of dissolved orthophosphate, significantly exchange the oxygen in precipitated apatite within environmental water3,4, which otherwise does not exchange with water at low temperatures. One of the enzymes that can cleave phosphates from organic substrates is alkaline phosphastase5, the enzyme also associated with bone mineralization. The literature often states that the mineral in bone in hydroxylapatite, however the mineral in bone is carbonated apatite that also contains some fluoride6. Deprotonation of HPO32- occurs at pH 12, which is impossibly high for biological system, and the predominate carbonate species in solution at neutral pH is HCO3-. To produce an apatite mineral without a significant hydroxyl content, it is possible that apatite biomineralization occurs through a polyphosphate pathway, where the oxygen atom required to transform polyphosphate into individual phosphate ions is from carbonate: [PO3-]n + CO32- -> [PO3-]n-1 + PO43- + CO2. Alkaline phosphatase can depolymerise polyphosphate into orthophosphate5. If alkaline phosphatase cleaves an oxygen atom from a calcium-carbonate complex, then there is no requirement for removing a hydrogen atom from the HCO3- or HPO43- ions of body water to form bioapatite. A mix of 1 mL of 1 M calcium polyphosphate hydogel, or nano-particles of calcium polyphosphate, and amorphous calcium carbonate were reacted with alkaline phosphatase, and maintained at neutral to basic pH. After two weeks, carbonated apatite and other calcium phosphate minerals were identified by powder x-ray diffraction. Orthophosphate and unreacted

  9. Combining apatite fission track and He thermochronology to constrain thermal histories

    Science.gov (United States)

    Persano, C.; Stuart, F.; Bishop, P.

    2003-04-01

    Apatite fission track thermochronometry (AFTT) has proved an invaluable tool for determining the cooling histories of rocks in the shallow crust. Quantitative models for the time and temperature dependence of the fission track annealing process in apatite demostrate that the combination of fission track apparent age and track length distribution provides a continuous record of the thermal history of the samples from 120 to 60^oC, and possibly, to lower temperatures. However the sensitivity of the technique is poorly constrained below 70-80^oC because annealing rates are slow. The apatite (U-Th)/He system is sensitive to temperatures between 80 and 40^oC irrespective of apatite chemistry, and presents a way to test the ability of AFTT to determine thermal histories below 80^oC. Here we present a novel way of combining apatite fission track and (U-Th)/He data that narrows the number of possible thermal histories and provides better constraints on the landscape evolution of a particular region. We use as an example the southeastern Australia passive margin in NSW, an area where post break-up landscape evolution is poorly resolved despite an extensive fission track database. Fission track and (U-Th)/He ages have been measured on 16 apatite samples from two coast perpendicular traverses across the coastal plain, up the escarpment onto the plateau. The fission track data are modelled using AFTSolve and the individual thermal histories which fit the data are used as parameters for forward modelling the apatite He ages. Only the thermal histories that produce the measured He age, within uncertainty, are considered. For each sample, the choosen time-temperature paths show the same peculiar characteristics, narrowing considerably the number of possible cooling scenarios. This combination shows that the AFT/derived thermal histories for temperatures between 60 to 40^oC may be inconsistent with the (U-Th)/He ages, suggesting that the annealing process at this temperatures

  10. Using the chemical analysis of magnetite to constrain various stages in the formation and genesis of the Kiruna-type chadormalu magnetite-apatite deposit, Bafq district, Central Iran

    Science.gov (United States)

    Heidarian, Hassan; Lentz, David; Alirezaei, Saeed; Peighambari, Sima; Hall, Douglas

    2016-03-01

    Textural and compositional data are presented for different types of magnetite in the Chadormalu iron deposit to discern the genesis of various styles of mineralization. Samples were chosen according to their paragenetic relations to apatite and their host setting: magnetite-apatite veins in the altered host rocks, disseminated magnetite-apatite assemblages in the marginal parts of the main ore body, and massive magnetite associated with irregular apatite veinlets from internal part of the main ore body. Scanning electron microscopy - back scatter electron (SEM-BSE) images reveal that there are three main generations of magnetite in each of the different magnetite-apatite assemblages. Primary magnetite (Mag1) features abundant porosity and a dark appearance. A second generation of magnetite (Mag2) replacing Mag1 shows a lighter appearance with both sharp and gradational contacts with the primary magnetite crystals. The two magnetite types are related to dissolution-precipitation processes due to changing physico-chemical parameters of the ore fluids. A third type of magnetite (Mag3) with a recrystallized appearance and foam-like triple junctions was mostly observed in magnetite-apatite veins in the main ore body and in veins hosted by altered rocks. Electron probe microanalyses (EPMA) were utilized to discriminate the various magnetite generations in the different magnetite-apatite assemblages. Applying published elemental discrimination diagrams shows that most primary magnetites fall into the hydrothermal- and Kiruna-type fields. Primary magnetite contains lower FeO (88.77-93.65 wt.%; average 91.5 wt.%), and higher SiO2 (0.21-2.26 wt.%; ave. 0.32 wt.%), Al2O3 (0.001-0.45 wt.%; ave. 0.053 wt.%), and CaO (0.002-0.48 wt.%; ave. 0.078 wt.%) contents, which might be related to magmatically derived fluids. Secondary magnetites have higher FeO (89.23-93.49 wt.%; ave. 92.11 wt.%), lower SiO2 (0.037-0.189 wt.%; ave. 0.072 wt.%), Al2O3 (0.004-0.072 wt.%; ave. 0.019 wt

  11. Resolving the chronology of the South African landscape through joint inverse modelling of AFT and apatite (U-Th)/He data

    Science.gov (United States)

    Wildman, Mark; Brown, Roderick; Beucher, Romain; Persano, Cristina; Stuart, Finlay

    2013-04-01

    (AHe) (e.g. [4]). AHe is ideally suited to this task as it is sensitive over a lower temperature range (c. 40-75±5°C) and can therefore provide insights into erosion on the scale of 1-3 km. Correlating AFT and AHe datasets can be difficult due to variations in U and Th zonation, crystal geometry and structural defects (e.g. radiation damage) altering the closure temperature of the AHe system and resulting in significant dispersion of ages. It is therefore essential to fully understand the major cause of age dispersion and use thermal history modelling techniques that take these factors into account. Here we present a new suite of apatite (U-Th)/He data from samples along the Orange River alongside complimentary apatite fission track data from the same samples. Two samples with a large number of analysed grains, JN2 and GGO2 (23 and 21 grains, respectively) were modelled using HelFrag [5] which takes into account dispersion in AHe ages produced through analysis fragments of larger apatite grains. These modelled histories where compared with inverse modelling using QTQt [6] to extract thermal history information for each of the samples and provide new insights into the post-Cretaceous evolution of the SW African landscape and the behaviour of complex dispersion patterns commonly observed in AHe data sets. [1] Brown, R.W., Summerfield, M.A., and Gleadow, A.J.W., 2002, Denudational history along a transect across the Drakensberg Escarpment of southern Africa derived from apatite fission track thermochronology: Journal of Geophysical Research, v. 107, p. B12, 2350. [2] Kounov, A., Viola, G., de Wit, M., and Andreoli, M.A.G., 2009, Denudation along the Atlantic passive margin: new insights from apatite fission-track analysis on the western coast of South Africa: Geological Society, London, Special Publications, v. 324, p. 287-306. [3] Partridge, T.C., and Maud, R.R., 1987, Geomorphic evolution of southern Africa since the Mesozoic: South African Journal of Geology, v. 90

  12. Inhibition of crystallization caused by Proteus mirabilis during the development of infectious urolithiasis by various phenolic substances.

    Science.gov (United States)

    Torzewska, Agnieszka; Rozalski, Antoni

    2014-01-01

    Infectious urolithiasis is a consequence of persistent urinary tract infections caused by urease producing bacteria e.g. Proteus mirabilis. These stones are composed of struvite and carbonate apatite. Their rapid growth and high recurrence indicate that so far appropriate methods of treatment have not been found. In the present study, the inhibitory effect of phenolic compounds was investigated in vitro against formation of struvite/apatite crystals. The impact of these substances with different chemical structures on crystallization caused by clinical isolates of P. mirabilis was tested spectrophotometrically using a microdilution method. Among the 11 tested compounds resveratrol, epigallocatechin gallate, peralgonidin, vanillic and coffee acids at the concentrations 250-1000 μg/ml inhibited P. mirabilis urease activity and crystallization. However, only vanillic acid had such an effect on all tested strains of P. mirabilis. Therefore, using an in vitro model, bacterial growth, crystallization, urease activity and pH were examined for 24h in synthetic urine with vanillic acid. Effect of vanillic acid was compared with that of other known struvite/apatite crystallization inhibitors (acetohydroxamic acid, pyrophosphate) and it was shown that vanillic acid strongly inhibited bacterial growth and the formation of crystals. It can be assumed that this compound, after further studies, can be used in the treatment or prophylaxis of infectious urolithiasis. PMID:24239192

  13. Geology, alteration, age, and origin of iron oxide-apatite deposits in Upper Eocene quartz monzonite, Zanjan district, NW Iran

    Science.gov (United States)

    Nabatian, Ghasem; Ghaderi, Majid; Corfu, Fernando; Neubauer, Franz; Bernroider, Manfred; Prokofiev, Vsevolod; Honarmand, Maryam

    2014-02-01

    Iron oxide-apatite deposits are present in Upper Eocene pyroxene-quartz monzonitic rocks of the Zanjan district, northwestern Iran. Mineralization occurred in five stages: (1) deposition of disseminated magnetite and apatite in the host rock; (2) mineralization of massive and banded magnetite ores in veins and stockwork associated with minor brecciation and calcic alteration of host rocks; (3) deposition of sulfide ores together with potassic alteration; (4) formation of quartz and carbonate veins and sericite, chlorite, epidote, silica, carbonate, and tourmaline alteration; and (5) supergene alteration and weathering. U-Pb dating of monazite inclusions in the apatite indicates an age of 39.99 ± 0.24 Ma, which is nearly coeval with the time of emplacement of the host quartz monzonite, supporting the genetic connection. Fluid inclusions in the apatite have homogenization temperatures of about 300 °C and oxygen isotopic compositions of the magnetite support precipitation from magmatic fluids. Late-stage quartz resulted from the introduction of a cooler, less saline, and isotopically depleted fluid. The iron oxide-apatite deposits in the Tarom area of the Zanjan district are typical of a magmatic-hydrothermal origin and are similar to the Kiruna-type deposits with respect to mineral assemblages, fabric and structure of the iron ores, occurrence of the ore bodies, and wall rock alteration.

  14. Enhanced apatite formation on Ti metal heated in P{sub O2}-controlled nitrogen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Masami, E-mail: masami@jfcc.or.jp; Hayashi, Kazumi, E-mail: k_hayashi@jfcc.or.jp; Kitaoka, Satoshi, E-mail: kitaoka@jfcc.or.jp

    2013-10-15

    The oxynitridation of biomedical titanium metal under a precisely regulated oxygen partial pressure (P{sub O2}) of 10{sup −14} Pa in nitrogen atmosphere at 973 K for 1 h strongly enhanced apatite formation compared with that on Ti heated in air. The factors governing the high apatite-forming ability are discussed from the viewpoint of the surface properties of Ti heated under a P{sub O2} of 10{sup −14} Pa in nitrogen atmosphere determined from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. Nitrogen (N)-doped TiO{sub 2} (interstitial N) was formed on pure Ti heated under a P{sub O2} of 10{sup −14} Pa in nitrogen atmosphere at 973 K. The XPS O1s main peak shifted toward a lower binding energy upon heating under a P{sub O2} of 10{sup −14} Pa. This shift may be due to the formation of oxygen vacancies. This Ti surface had a positive zeta potential of approximately 20 mV. According to time-of-flight secondary ion mass spectroscopy results, PO{sub 4}{sup 3−} ions were predominantly adsorbed on Ti soaked in simulated body fluid (SBF) after heat treatment, followed by calcium ions. It was concluded that the apatite formation kinetics can be described using the Avrami–Erofeev equation with an Avrami index of n = 2, which implies the instantaneous nucleation of apatite on the surface of Ti soaked in SBF after heat treatment at 973 K under a P{sub O2} of 10{sup −14} Pa. - Highlights: • Nitrogen-doped TiO{sub 2} was formed on Ti heated under a P{sub O2} of 10{sup −14} Pa. • Oxygen vacancy was existed on the outermost layer of nitrogen-doped TiO{sub 2}. • This nitrogen-doped TiO{sub 2} surface had a positive zeta potential of 20 mV. • PO{sub 4}{sup 3−} ions were predominantly adsorbed on the nitrogen-doped TiO{sub 2} soaked in SBF.

  15. SAXS study on the morphology of etched and un-etched ion tracks in apatite

    Directory of Open Access Journals (Sweden)

    Nadzri A.

    2015-01-01

    Full Text Available Natural apatite samples were irradiated with 185 MeV Au and 2.3 GeV Bi ions to simulate fission tracks. The resulting track morphology was investigated using synchrotron small angle x-ray scattering (SAXS measurements before and after chemical etching. We present preliminary results from the SAXS measurement showing the etching process is highly anisotropic yielding faceted etch pits with a 6-fold symmetry. The measurements are a first step in gaining new insights into the correlation between etched and unetched fission tracks and the use of SAXS as a tool for studying etched tracks.

  16. Emplacement time of Salai Patai carbonatite, Malakand, Pakistan, from fission track dating of zircon and apatite

    Energy Technology Data Exchange (ETDEWEB)

    Qureshi, A.A.; Khan, H.A. (N.E.D., Nilore, Islamabad (Pakistan). SSNTD-Lab.); Butt, K.A. (Atomic Energy Minerals Centre, Lahore (Pakistan))

    1991-01-01

    Based on fission track dating of zircon and apatite, the emplacement history of Salai Patai carbonatite has been traced. It has been estimated that the carbonatite was emplaced along the thrust plane associated with the Indian-Eurasian plate collision during the Oligocene period followed by some thermal/tectonic episode during Early Miocene. This negates the previous proposal that all carbonatites found in Pakistan are a part of a 200 km long alkaline province associated with the rifting of Peshawar Valley during Late Cretaceous or early tertiary. (author).

  17. Extraction of rare earth elements from hydrate-phosphate precipitates of apatite processing

    Science.gov (United States)

    Andropov, M. O.; Anufrieva, A. V.; Buynovskiy, A. S.; Makaseev, Y. N.; Mazov, I. N.; Nefedov, R. A.; Sachkov, V. I.; Stepanova, O. B.; Valkov, AV

    2016-01-01

    The features of extraction of rare earth elements (REE) were considered from hydrate-phosphate precipitates of REE of apatite processing by nitric acid technology. The preliminary purification of nitrate solution of REE from impurities of titanium, aluminum, iron, uranium and thorium was suggested to obtain stable solutions not forming precipitates. Washing the extract was recommended with the evaporated reextract that allows to obtain directly on the cascade of REE extraction the concentrated solutions suitable for the separation into groups by the extraction method. Technical decisions were suggested for the separation of REE in groups without the use of salting-out agent.

  18. Crystal Meth

    Science.gov (United States)

    ... for: Navigation Home / Stories of Hope / Crystal meth Crystal meth Story Of Hope By giovanni January 3rd, ... about my drug addiction having to deal with Crystal meth. I am now in recovery and fighting ...

  19. Bone-like apatite formation on HA/316L stainless steel composite surface in simulated body fluid

    Institute of Scientific and Technical Information of China (English)

    FAN Xin; CHEN Jian; ZOU Jian-peng; WAN Qian; ZHOU Zhong-cheng; RUAN Jian-ming

    2009-01-01

    HA/316L stainless steel(316L SS) biocomposites were prepared by hot-pressing technique. The formation of bone-like apatite on the biocomposite surfaces in simulated body fluid(SBF) was analyzed by digital pH meter, plasma emission spectrometer, scanning electron microscope(SEM) and energy dispersive X-ray energy spectrometer(EDX). The results indicate that the pH value in SBF varies slightly during the immersion. It is a dynamic process of dissolution-precipitation for the formation of apatite on the surface. With prolonging immersion time, Ca and P ion concentrations increase gradually, and then approach equilibrium. The bone-like apatite layer forms on the composites surface, which possesses benign bioactivity and favorable biocompatibility and achieves osseointegration, and can provide firm fixation between HA60/316L SS composite implants and human body bone.

  20. Lattice energies of apatites and the estimation of DeltaH f degrees (PO 4 3-, g).

    Science.gov (United States)

    Flora, Natalie J; Yoder, Claude H; Jenkins, H Donald Brooke

    2004-04-01

    Experimentally based lattice energies are calculated for the apatite family of double salts M(5)(PO(4))(3)X, where M is a divalent metal cation (Ca, Sr, Ba) and X is hydroxide or a halide. These values are also shown to be estimable, generally to within 4%, using the recently derived Glasser-Jenkins equation, U(POT) = AI(2I/V(m))(1/3), where A = 121.39 kJ mol(-)(1). The apatites exhibiting greater covalent character (e.g., M = Pb, Cd, etc.) are less well reproduced but are within 8% of the experimentally based value. The lattice energy for ionic apatites (having identical lattice ionic strengths, I) takes the particularly simple form U(POT)/kJ mol(-)(1) = 26680/(V(m)/nm(3))(1/3), reproducing cycle values of U(POT) well when V(m) is estimated by ion volume summation and employing a volume for the PO(4)(3)(-) ion (not previously quantified with an associated error) of 0.063 +/- 0.003 nm(3). A value for the enthalpy of formation of the gaseous phosphate ion, DeltaH(f)( ) degrees (PO(4)(3)(-), g), is absent from current thermochemical tabulations. Examination of solution and solid state thermochemical cycles for apatites, however, leads us to a remarkably consistent value of 321.8 +/- 1.2 kJ mol(-)(1). Experimental and estimated lattice energies were used along with other thermodynamic data to determine enthalpies, entropies, and free energies of dissolution for apatites of uncertain stabilities. These dissolution values are compared with the corresponding values for stable apatites and are used to rationalize the relative instability of certain derivatives.

  1. OH defects in quartz in granitic systems doped with spodumene, tourmaline and/or apatite: experimental investigations at 5-20 kbar

    Science.gov (United States)

    Frigo, C.; Stalder, R.; Hauzenberger, C. A.

    2016-07-01

    The incorporation of OH defects in quartz as a function of Li content in the bulk system and pressures was investigated. Quartz crystals were grown in water-saturated granitic systems, containing various amounts Li, B and P, supplied as accessory phases such as spodumene, tourmaline or apatite in the starting mixtures. High pressure experiments were performed at temperatures between 900 and 1100 °C, and pressures between 5 and 20 kbar with a piston cylinder apparatus, and the synthesized quartz crystals were analyzed by IR spectroscopy, electron microprobe and LA-ICP-MS spectroscopy. All IR absorption spectra revealed absorption features that can be assigned to AlOH (3313, 3379 and 3431 cm-1) and (4H)Si defects (3585 cm-1), whereas quartz grown in the Li and B systems exhibited two additional bands related, respectively, to LiOH (3483 cm-1) and BOH defects (3596 cm-1). It was further observed that LiOH incorporation increases with higher spodumene content in the starting material and decreases with pressure, until no LiOH defects are observed at pressure higher than 15 kbar. Specifically, the most pronounced reduction of LiOH defects occurs in a rather narrow pressure interval (10-15 kbar) close to the high-quartz/low-quartz transition. However, the link between the transition and the defect incorporation remains unclear. Li total concentrations always exceed the Li-coupled LiOH defects, suggesting the simultaneous presence of dry AlLi defects. Results of this study suggest that LiOH defects are detectable only in quartz crystals grown from middle and upper crustal sections (such as hydrothermal quartz) and not in quartz from deep roots of orogenic granitoids.

  2. The role of the counter-ions present in syntheses on the thermal stabilization of strontium and/or calcium apatites

    Energy Technology Data Exchange (ETDEWEB)

    Melo da Silva, Leila; Santos Menezes, Daniela dos; Almeida, Luis Eduardo [Laboratório de Biomateriais – P" 2CEM, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n, São Cristóvão, 49100-000 Sergipe (Brazil); Anselme, Karine; Dentzer, Joseph [Institut de Science des Matériaux de Mulhouse (IS2M), CNRS UMR7361, Université de Haute-Alsace, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse (France); Araujo dos Santos, Euler, E-mail: euler@ufs.br [Laboratório de Biomateriais – P" 2CEM, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n, São Cristóvão, 49100-000 Sergipe (Brazil)

    2015-09-15

    Highlights: • Counter-ions present in syntheses can affect thermal stabilization of apatites. • Ions with different charges and sizes can stabilize the apatite structure. • Co-substitution is an important way to design biomimetic hydroxyapatites. - Abstract: The goal of this work was to study the thermal stabilization of calcium apatites in which the Ca{sup 2+} ions were substituted for Sr{sup 2+} in increasing concentrations via ionic co-substitutions. Two distinct standard syntheses were proposed for comparative purposes: one using counter-ions that were not easily incorporated into the apatite structure (NH{sub 4}{sup +}/NO{sub 3}{sup −}) and one using counter-ions that can be easily incorporated into the structure (Na{sup +}/Cl{sup −}). After calcination, only the apatites synthesized in the presence of NH{sub 4}{sup +}/NO{sub 3}{sup −} presented phase transformation. In contrast, the apatites synthesized in the presence of Na{sup +}/Cl{sup −} formed a solid solution after calcination, with Na{sup +}, Ca{sup 2+}, Sr{sup 2+} and Cl{sup −} sharing the same apatite lattice. Wavelength dispersive X-ray fluorescence spectroscopy (WDXRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and temperature-programmed desorption (TPD) techniques showed that the counter-ions present during the syntheses that are associated with CO{sub 3}{sup 2−} play an important role in the thermal stabilization of the apatites.

  3. The role of the counter-ions present in syntheses on the thermal stabilization of strontium and/or calcium apatites

    International Nuclear Information System (INIS)

    Highlights: • Counter-ions present in syntheses can affect thermal stabilization of apatites. • Ions with different charges and sizes can stabilize the apatite structure. • Co-substitution is an important way to design biomimetic hydroxyapatites. - Abstract: The goal of this work was to study the thermal stabilization of calcium apatites in which the Ca2+ ions were substituted for Sr2+ in increasing concentrations via ionic co-substitutions. Two distinct standard syntheses were proposed for comparative purposes: one using counter-ions that were not easily incorporated into the apatite structure (NH4+/NO3−) and one using counter-ions that can be easily incorporated into the structure (Na+/Cl−). After calcination, only the apatites synthesized in the presence of NH4+/NO3− presented phase transformation. In contrast, the apatites synthesized in the presence of Na+/Cl− formed a solid solution after calcination, with Na+, Ca2+, Sr2+ and Cl− sharing the same apatite lattice. Wavelength dispersive X-ray fluorescence spectroscopy (WDXRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and temperature-programmed desorption (TPD) techniques showed that the counter-ions present during the syntheses that are associated with CO32− play an important role in the thermal stabilization of the apatites

  4. The transantarctic mountains: A natural laboratory for apatite fission-track analysis. Results from Italian antarctic expeditions

    International Nuclear Information System (INIS)

    Apatite fission-track analysis has been applied to samples collected during the 1991/1992, 1993/1994 and 1996/1997 campaigns of the Italian Antarctic Project in the Transantarctic Mountains. Samples from the first two campaigns, collected in the area between the Mariner and the David Glaciers (northern Victoria Land), reveal that a Late Cretaceous uplift - denudation phase already identified in other sectors of the chain took place also in this region. They also confirm the occurrence of a more recent phase starting in the Late Paleocene. Offsets in apatite age profiles regarding samples collected further north during the third campaign reveal Cenozoic normal faulting with variable sense of offset

  5. Calibration of the Fluorine, Chlorine and Hydrogen Content of Apatites With the ChemCam LIBS Instrument

    Science.gov (United States)

    Meslin, P.-Y.; Cicutto, L.; Forni, O.; Drouet, C.; Rapin, W.; Nachon, M.; Cousin, A.; Blank, J. G.; McCubbin, F. M.; Gasnault, O.; Newsom, H.; Mangold, N.; Schroeder, S.; Sautter, V.; Maurice, S.; Wiens, R. C.

    2016-01-01

    Determining the composition of apatites is important to understand the behavior of volatiles during planetary differentiation. Apatite is an ubiquitous magmatic mineral in the SNC meteorites. It is a significant reservoir of halogens in these meteorites and has been used to estimate the halogen budget of Mars. Apatites have been identified in sandstones and pebbles at Gale crater by ChemCam, a Laser-Induced Breakdown Spectroscometer (LIBS) instrument onboard the Curiosity rover. Their presence was inferred from correlations between calcium, fluorine (using the CaF molecular band centered near 603 nm, whose detection limit is much lower that atomic or ionic lines and, in some cases, phosphorus (whose detection limit is much larger). An initial quantification of fluorine, based on fluorite (CaF2)/basalt mixtures and obtained at the LANL laboratory, indicated that the excess of F/Ca (compared to the stoichiometry of pure fluorapatites) found on Mars in some cases could be explained by the presence of fluorite. Chlorine was not detected in these targets, at least above a detection limit of 0.6 wt% estimated from. Fluorapatite was later also detected by X-ray diffraction (with CheMin) at a level of approx.1wt% in the Windjana drill sample (Kimberley area), and several points analyzed by ChemCam in this area also revealed a correlation between Ca and F. The in situ detection of F-rich, Cl-poor apatites contrasts with the Cl-rich, F-poor compositions of apatites found in basaltic shergottites and in gabbroic clasts from the martian meteorite NWA 7034, which were also found to be more Cl-rich than apatites from basalts on Earth, the Moon, or Vesta. The in situ observations could call into question one of the few possible explanations brought forward to explain the SNC results, namely that Mars may be highly depleted in fluorine. The purpose of the present study is to refine the calibration of the F, Cl, OH and P signals measured by the ChemCam LIBS instrument, initiated

  6. Histological Comparison in Rats between Carbonate Apatite Fabricated from Gypsum and Sintered Hydroxyapatite on Bone Remodeling

    Directory of Open Access Journals (Sweden)

    Yasunori Ayukawa

    2015-01-01

    Full Text Available Carbonate apatite (CO3Ap, the form of apatite found in bone, has recently attracted attention. The purpose of the present study was to histologically evaluate the tissue/cellular response toward the low-crystalline CO3Ap fabricated using a dissolution-precipitation reaction with set gypsum as a precursor. When set gypsum was immersed in a 100°C 1 mol/L Na3PO4 aqueous solution for 24 h, the set gypsum transformed into CO3Ap. Both CO3Ap and sintered hydroxyapatite (s-HAp, which was used as a control, were implanted into surgically created tibial bone defects of rats for histological evaluation. Two and 4 weeks after the implantation, histological sections were created and observed using light microscopy. The CO3Ap granules revealed both direct apposition of the bone matrix by osteoblasts and osteoclastic resorption. In contrast, the s-HAp granules maintained their contour even after 4 weeks following implantation which implied that there was a lack of replacement into the bone. The s-HAp granules were sometimes encapsulated with fibrous tissue, and macrophage polykaryon was occasionally observed directly apposed to the implanted granules. From the viewpoint of bone remodeling, the CO3Ap granules mimicked the bone matrix, suggesting that CO3Ap may be an appropriate bone substitute.

  7. Confined fission track lengths in apatite: A diagnostic tool for thermal history analysis

    International Nuclear Information System (INIS)

    A compilation of the lengths of confined fission tracks in a wide variety of apatites from different geological environments has shown that the distribution of confined track lengths can provide unique thermal history information in the temperature range below about 1500C over times of the order of 106 to 109 years. The continuous production of tracks through time, coupled with the fact that the length of each track shrinks to a value characteristic of the maximum temperature it has experienced, gives a final length distribution which directly reflects the nature of the variation of temperature with time. Most distinctive of the myriad possible forms of the final distribution are the bimodal distributions, which give clear evidence of a two-stage history, including high and low temperature phases. The study of confined length distributions therefore offers invaluable evidence on the meaning of any fission-track age, and bears the potential of providing rigorous constraints on thermal history in the temperature regime below about 1500C. The results of this study strongly suggest that any apatite fission-track age determination should be supported by a confined track length distribution. (orig./RB)

  8. Alternate dipping preparation of biomimetic apatite layers in the presence of carbonate ions

    International Nuclear Information System (INIS)

    The classical simulated body fluids method cannot be employed to prepare biomimetic apatites encompassing metallic ions that lead to very stable phosphates. This is the case for heavy metals such as uranium, whose presence in bone mineral after contamination deserves toxicological study. We have demonstrated that existing methods, based on alternate dipping into calcium and phosphate ions solutions, can be adapted to achieve this aim. We have also especially studied the impact of the presence of carbonate ions in the medium as these are necessary to avoid hydrolysis of the contaminating metallic cations. Both the apatite–collagen complex method and a standard chemical (STD) method employing only mineral solutions lead to biomimetic apatites when calcium and carbonate ions are introduced simultaneously. The obtained materials were fully characterized and we established that the STD method tolerates the presence of carbonate ions much better, and this leads to homogeneous samples. Emphasis was set on the repeatability of the method to ensure the relevancy of further work performed on series of samples. Finally, osteoblasts cultured on these samples also proved a similar yield and standard-deviation in their adenosine triphosphate content when compared to commercially available substrates designed to study of such cell cultures. (paper)

  9. A first report of hydroxylated apatite as structural biomineral in Loasaceae - plants' teeth against herbivores.

    Science.gov (United States)

    Ensikat, Hans-Jürgen; Geisler, Thorsten; Weigend, Maximilian

    2016-01-01

    Biomineralization provides living organisms with various materials for the formation of resilient structures. Calcium phosphate is the main component of teeth and bones in vertebrates, whereas especially silica serves for the protection against herbivores on many plant surfaces. Functional calcium phosphate structures are well-known from the animal kingdom, but had not so far been reported from higher plants. Here, we document the occurrence of calcium phosphate biomineralization in the South-American plant group Loasaceae (rock nettle family), which have stinging trichomes similar to those of the well-known stinging nettles (Urtica). Stinging hairs and the smaller, glochidiate trichomes contained nanocrystalline hydroxylated apatite, especially in their distal portions, replacing the silica found in analogous structures of other flowering plants. This could be demonstrated by chemical, spectroscopic, and diffraction analyses. Some species of Loasaceae contained both calcium phosphate and silica in addition to calcium carbonate. The intriguing discovery of structural hydroxylated apatite in plants invites further studies, e.g., on its systematic distribution across the family, the genetic and cellular control of plant biomineralization, the properties and ultrastructure of calcium phosphate. It may prove the starting point for the development of biomimetic calcium phosphate composites based on a cellulose matrix. PMID:27194462

  10. A first report of hydroxylated apatite as structural biomineral in Loasaceae – plants’ teeth against herbivores

    Science.gov (United States)

    Ensikat, Hans-Jürgen; Geisler, Thorsten; Weigend, Maximilian

    2016-01-01

    Biomineralization provides living organisms with various materials for the formation of resilient structures. Calcium phosphate is the main component of teeth and bones in vertebrates, whereas especially silica serves for the protection against herbivores on many plant surfaces. Functional calcium phosphate structures are well-known from the animal kingdom, but had not so far been reported from higher plants. Here, we document the occurrence of calcium phosphate biomineralization in the South-American plant group Loasaceae (rock nettle family), which have stinging trichomes similar to those of the well-known stinging nettles (Urtica). Stinging hairs and the smaller, glochidiate trichomes contained nanocrystalline hydroxylated apatite, especially in their distal portions, replacing the silica found in analogous structures of other flowering plants. This could be demonstrated by chemical, spectroscopic, and diffraction analyses. Some species of Loasaceae contained both calcium phosphate and silica in addition to calcium carbonate. The intriguing discovery of structural hydroxylated apatite in plants invites further studies, e.g., on its systematic distribution across the family, the genetic and cellular control of plant biomineralization, the properties and ultrastructure of calcium phosphate. It may prove the starting point for the development of biomimetic calcium phosphate composites based on a cellulose matrix. PMID:27194462

  11. Chemical Composition Determination Of Francolite Apatites By Fourier Transform Infrared (FTIR) Spectroscopy

    Science.gov (United States)

    Scheib, Robin M.; Thrasher, Raymond D.; Lehr, James R.

    1981-10-01

    Prior work by Lehr and McClellan and Lehr, based on chemical, crystallographic, and x-ray diffraction studies, showed the relationship between phosphate (P) and substituted carbonate (C) in francolite apatite to be P+C = 6.00 ± 0.04 and the generalized apatite formula to be (Ca,Na,Mg) 10(PO4)6-x(CO3)xFy(F,OH)2, in which y ranges from 0.33x to 0.5x. Using the FTIR, the ratio of the area of the absorption curve for C-0 (bands in the region 1375 to 1550 cm-1) versus the area of the absorption curve for P-0 (bands in the region 530 to 690 cm-1), the "CO2 index," was found to be proportional to the mole ratio of CO3:PO4 in francolites. Stripping methods allowed the subtraction of spectral contributions of silicate and carbonate minerals and water, which would ordinarily interfere with such a determination. The study was based on 65 mineral samples and the formula was found to be: CO2 index = 0.0678 + 4.184(mole ratio CO3:PO4) (1) The correlation factor, r2, was 0.938 and the standard error of the slope ±0.136. The probability of the null hypothesis for the model was less than 0.0001.

  12. Electrodeposited apatite coating for solid-phase microextraction and sensitive indirect voltammetric determination of fluoride ions.

    Science.gov (United States)

    Mao, Yuehong; Chen, Yufei; Chu, Lin; Zhang, Xiaoli

    2013-10-15

    Electrodeposition was used to prepare a new solid phase microextraction (SPME) coatings. Two apatite SPME coatings, dicalcium phosphate dihydrate (DCPD or brushite) and hydroxyapatite (HAP) were validly and homogeneously one-step electrodeposited on glassy carbon electrode (GCE) under different conditions. The coatings were characterized by XRD, FTIR, SEM, CV and EIS. The apatite SPME coatings showed excellent and selective adsorbability to fluoride ions. A novel indirect voltammetric strategy for sensitive detection of fluoride was proposed using K3Fe(CN)6 as indicating probe. The detection principle of fluoride ions was based on the increment of steric hindrance after fluoride adsorption, which resulting in the decrease of the amperometric signal to Fe(CN)6(3-). The liner ranges were 0.5-20.0 μmol/L for n-DCPD/GCE with the limit of detection of 0.14 μmol/L and 0.1-50.0 μmol/L for n-HAP/GCE with the limit of detection of 0.069 μmol/L, respectively. The developed method was applied to the analysis of water samples (lake, spring and tap water) and the recovery values were found to be in the range of 90-106%. PMID:24054624

  13. Microwave assisted apatite coating deposition on Ti6Al4V implants.

    Science.gov (United States)

    Zhou, Huan; Nabiyouni, Maryam; Bhaduri, Sarit B

    2013-10-01

    In this work we report a novel microwave assisted technology to deposit a uniform, ultra-thin apatite coating without any cracks on titanium implants in minutes. This method comprises of conventional biomimetic coating in synergism with microwave irradiation to result in alkaline earth phosphate nucleation. The microwave assisted coating process mainly follows the initial stages of biomimetic coating until the step of the Ca-P nuclei formation. After that, due to microwave irradiation more Ca-P nuclei are formed to cover the whole surface of the implant instead of the growth of deposited Ca-P nuclei to Ca-P globules and coatings. It is interesting to note the doping of Mg(2+) to Ca-P apatite coating can significantly change the properties and performances of as-deposited coatings. The hydrophilicity, physical properties, bioactivity, cell adhesion, and growth capability of as-deposited microwave assisted coatings were investigated. The study shows that this coating technology has great potential in biomedical applications. Additionally, since biomimetic coating can be applied to series of implant materials such as polymer, metals and glass, it is expected this microwave assisted coating technology can also be applied to these materials if they can remains stable at 100 °C, the boiling point of water.

  14. Enhancement of the ALP activity of C3H10T1/2 cells by the combination of an oxysterol and apatite

    Energy Technology Data Exchange (ETDEWEB)

    Son, Kyung Mi; Park, Hee Chul; Kim, Na Ryoung; Yang, Hyeong-Cheol [Department of Dental Biomaterials Science, Dental Research Institute, School of Dentistry, Seoul National University, Yeonkun-dong, Chongro-ku, Seoul 110-749 (Korea, Republic of); Lee, In-Seop, E-mail: yanghc@snu.ac.k [Atomic-scale Surface Science Research Center, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2010-08-01

    Biomimetic apatite coating has been used to load osteogenic biomolecules onto the surface of titanium implants. Apatite on the surface of biomaterials is thought to function as a reservoir of biomolecules as well as enhancing osteoconductivity. In this study, 20{alpha}-hydroxycholesterol (20{alpha}-HC), an osteogenic oxysterol, was used to induce differentiation of a mouse embryo fibroblast cell line (C3H10T1/2) by loading the oxysterol on biomimetically coated apatite of titanium discs. We found that the phosphatase (alkaline phosphatase (ALP)) activity of 20{alpha}-HC was significantly higher with ascorbic acid than alone, suggesting a need for ascorbic acid as a co-factor. When 20{alpha}-HC was added into the apatite coating solution, the ALP activity of the C3H10T1/2 cells did not increase on the apatite surface, even in the presence of ascorbic acid. However, ALP activity increased dramatically when 20{alpha}-HC was loaded by volatilization of EtOH from the apatite coat after dipping discs in 20{alpha}-HC-dissolved EtOH. Interestingly, ascorbic acid was not needed for this increase in ALP activity, suggesting a synergistic effect of 20{alpha}-HC and apatite. The concentration of calcium ions, a major component of apatite, affected the osteogenic effect of 20{alpha}-HC, and the increase in ALP activity was attenuated by L-type calcium channel inhibitors, verapamil and nifedipine. These results demonstrate that calcium ions released from apatite are important in the synergistic effect of 20{alpha}-HC and apatite.

  15. 藏南北喜马拉雅穹窿高Sr/Y二云母花岗岩中磷灰石地球化学特征及其岩石学意义%The geochemical nature of apatites in high Sr/Y two-mica granites from the North Himalayan Gneiss Domes, southern Tibet

    Institute of Scientific and Technical Information of China (English)

    曾令森; 陈晶; 高利娥; 陈振宇

    2012-01-01

    Recent investigations in the Yardoi gneiss dome, the easternmost one of the Northern Himalayan Gneiss Domes (NHGD), have identified two suites of high Sr/Y two-mica granites (TMG) formed at ca. 43-44 Ma and ca. 18-20 Ma, respectively. Though they differ substantially in the Sr-Nd isotope systematics and the timing of formation, they show similar characteristics in mineral assemblage as well as in element geochemistry ( e. g. high CaO and Sr contents, high Na/K and Sr/Y ratios). LA-ICP-MS analyses were carried out on apatite grains from these TMGs to investigate the geochemical behavior of apatite during their magmatic evolution. Analytical results show that: (1) trace element partitioning behavior between apatite and granitic melt are similar in these TMGs; (2) the Eocene TMG contains relict apatite, possibly inherited from its source; ( 3) relatively large scattering in trace element compositions among individual apatite grains from the same sample is due to chemical variations in local melts in equilibrium with apatite; (4) fractional crystallization of plagioclase rich in anorthite component had played a primary role in regulating the chemical compositions (e. g. Ca, Na, Sr, and LREE) of melts that crystallized apatite. Our investigation demonstrates that combined investigation of the growth textures and chemical compositions of apatite and plagioclase could yield important insights on the petrogenesis of granitoids.%北喜马拉雅穹窿最东部的雅拉香波穹窿发育两套高Sr/Y比值二云母花岗岩,分别形成于始新世(约43 ~ 44Ma)和中新世(约18~ 20Ma).虽然在Sr-Nd同位素系统特征和形成时代上存在明显差异之外,但无论在矿物组成,还是在元素地球化学(高CaO,高Na/K和Sr/Y比值等)特征上,这两套花岗岩都存在高度相似性.为探讨在这两套花岗质岩浆形成和演化过程中,磷灰石的地球化学行为特征,应用LA-ICP-MS分析了磷灰石的微量元素地球化

  16. Microchemical and structural regular variability of apatites in 'overbuilt' enamel and dentin of human molar teeth

    International Nuclear Information System (INIS)

    The aim of a recent paper was to recognize the chemical and structural changes in apatites, which form both the enamel and the dentin of the human tooth. The aim was achieved by scrutinizing the linear elemental profiles along the cross-sections of human molar teeth. Essentially, the task was accomplished with the application of the Electron Probe Microanalysis method and with some additional studies by Micro-Raman spectrometry. All the trends in linear profiles were strictly determined. In the enamel zone they were either increasing or decreasing curves of exponential character. The direction of the investigations was to start with the tooth surface and move towards the dentin-enamel junction (DEJ). The results of the elemental studies were more visible when the detected material was divided, in an arbitrary way, into the prevailing 'core' enamel (∼93.5% of the total mass) and the remaining 'overbuilt' enamel. The material in the 'core' enamel was fully stable, with clearly determined chemical and mechanical features. However, the case was totally different in the 'overbuilt enamel', with dynamic changes in the composition. In the 'overbuilt' layer Ca, P, Cl and F profiles present the decaying distribution curves, whereas Mg, Na, K and CO32- present the growing ones. Close to the surface of the tooth the mixture of hydroxy-, chlor- and fluor-apatite is formed, which is much more resistant than the rest of the enamel. On passing towards the DEJ, the apatite is enriched with Na, Mg and CO32-. In this location, three of six phosphate groups were substituted with carbonate groups. Simultaneously, Mg is associated with the hydroxyl groups around the hexad axis. In this way, the mechanisms of exchange reactions were established. The crystallographic structures were proposed for new phases located close to DEJ. In the dentin zone, the variability of elemental profiles looks different, with the most characteristic changes occurring in Mg and Na concentrations. Mg

  17. Thermal History of Drummond Basin, Queensland (Australia) from Apatite and Zircon (U-Th)/He Thermochronology

    Science.gov (United States)

    Zhang, W.; Min, K. K.; Bryan, S. E.

    2014-12-01

    The thermal history of the Drummond Basin in central Queensland (Australia) has only been partly investigated. Inverse thermal modeling of apatite and zircon (U-Th)/He data can reveal the complex thermal history of sedimentary basins. We performed (U-Th)/He dating for detrital apatite and zircon grains extracted from five sandstone samples from the Campaspe DDH-1 drill hole. Mean apatite helium ages generally increase from 65.9 Ma (depth = 538 m) to 83.8 Ma (depth = 263 m). The deeper four samples yielded mean zircon helium (ZHe) ages of 289.7 - 278.2 Ma, with a systematic increase of the ZHe ages from deep to shallow samples. The shallowest sample (depth = 117 m) yielded a mean ZHe age of 263.6 Ma. Our inverse thermal modeling suggests five thermal events since burial: (1) rapid heating to the maximum temperature of 180~380 oC during ~320-290 Ma, (2) rapid cooling from ~260 oC to ~80 oC during ~290-240 Ma, (3) subdued cooling from ~80 oC to ~30 oC during ~240-200 Ma, (4) slow heating from ~30 oC to ~80 oC during ~200-80 Ma, followed by (5) rapid cooling from ~80 oC to ~35 oC at ~80 Ma. The timing and temperature conditions of the initial thermal event are consistent with K/Ar ages and temperatures deduced from illite. This period was characterized by voluminous regional magmatism and crustal extension preceding opening of the overlying Bowen Basin. Rapid cooling during ~290-240 Ma identified by our inverse thermal modeling roughly coincides with the thermal relaxation phase and foreland basin phase of the overlying Bowen Basin. This rapid cooling was probably a result of cessation of extension and subsequent contractional events to the east of Bowen Basin. Cooling slowed down during ~240-200 Ma. The Drummond Basin probably underwent serious erosion during this period, coeval with the peneplanation phase of the Bowen Basin. As is delineated by our modeling, the Drummond Basin was slowly heated from ~20 oC to ~90 oC during ~200-80 Ma, synchronous with development of

  18. The Influence of Nano-apatite on c-myc and p53 Gene in the Hepatocellular Carcinoma

    Institute of Scientific and Technical Information of China (English)

    CHEN Jun; CAO Xianying; LI Shipu; HAN Yingchao; ZHANG Ran

    2005-01-01

    The influence mechanism of the nano-apatite on the human hepatocellular carcinoma in vitro was investigated. Using the homogeneous precipitation method, the nano-apatite was synthesized at room temperature, and it was characterized with transmission electron microscopy (TEM) and the Zataplus. The influence on the expression of the c-myc and p53 gene in the human hepatocellular carcinoma cell lines were tested with the TEM and hybridization in situ. The TEM and the Zataplus analyses show that the nano-apatite is distributed homogenously in size and needle-shaped sizes, which ranges from 67.5 nm to 88.3 nm. It is found that the nano-apatitet increases the volume of the human hepatocellular carcinoma cells, makes extensive cytoplasmic vacuolization, the mitochondria swelling, chromatin in nucleus dispersed partially and condensed around the nuclear membranes.The interspace in nuclear membranes were separated and even the cytoplasm dissolved. It is also found that the expression of the c-myc gene is inhibited, but the p53 is enhanced. The experimental results demonstrate that the nano-apatite enables the oncosis of the human hepatocellular carcinoma cells by down-regulation of the expression of the c-myc and up-regulation of the expression of the p53 in vitro.

  19. Removal of fluoride from aqueous solution by adsorption on Apatitic tricalcium phosphate using Box-Behnken design and desirability function

    Science.gov (United States)

    Mourabet, M.; El Rhilassi, A.; El Boujaady, H.; Bennani-Ziatni, M.; El Hamri, R.; Taitai, A.

    2012-03-01

    The adsorption method was used for fluoride removal from aqueous solution by Apatitic tricalcium phosphate. In this study, response surface methodology was employed for the removal of fluoride. Experiments were carried out as per Box-Behnken surface statistical design with four input parameters namely adsorbent dose (0.1-0.3 g), initial concentration (30-60 mg L-1), temperature (20-40 °C) and pH (4-11). Contact time (90 min) was taken as a fixed input parameter. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination (R2) value of 0.966 and Fisher F-value of 10.28. Applying the method of the desirability function, optimization of adsorbent dose (29 g), initial concentration (60 mg L-1), T (40 °C) and pH (4) gave a maximum of 82.34% fluoride removal white desirability of 0.916 by Apatitic tricalcium phosphate. Dynamic adsorption data were applied to pseudo-first-order and pseudo-second-order rate equations. Pseudo-second-order kinetic model well expressed fluoride adsorption onto Apatitic tricalcium phosphate. According to the correlation coefficients, the adsorption of fluoride on the Apatitic tricalcium phosphate was correlated well with the Langmuir and Freundlich models.

  20. The geology, geochemistry and magnetite-apatite mineralization of the Avnik area, Genç-Bingöl, SE Turkey

    NARCIS (Netherlands)

    Aral, H.

    1986-01-01

    In this thesis the results of a study on the geology, geochemistry and magnetite-apatite mineralization of the Avnik area, southeast Turkey, are presented. Conclusions are drawn with respect to the origin and the way of emplacement of the mineralization. The study area is part of the Bitlis Massif w

  1. Determination of rare earth elements, uranium and thorium in apatite minerals by inductively coupled plasma-mass spectrometry

    International Nuclear Information System (INIS)

    Determination and distribution of 18 elements such as rare earth elements (REE), uranium and thorium in apatite minerals were examined using inductively coupled plasma-mass spectrometry. The sample solution (1 mg/ml) which were prepared with hot concentrated nitric acid were directly injected into the plasma. REE, uranium and thorium contents in the apatite were determined by a calibration curve method. However, the intensity of thorium decreased by calcium phosphate in macro-component. Therefore, thorium was separated from these calcium phosphate by solvent extraction with 0.1 mol/dm3 3-Phenyl-4-benzoyl-5-isoxazolone-DIBK system. DIBK phase was evaporated by heating, dried and ashed with concentrated nitric and perchloric acids. After allowing cooling, 0.1 mol/dm3 nitric acids was added to dissolve any precipitate. The REE, uranium and thorium content in apatite minerals from USA, China and Jordan were found to be (0.24-172), (9.69-111), (0.7-7.95) ppm, respectively. It was found that lanthanoid in apatite minerals following the Oddo and Harkins law. (author)

  2. Combination of Slag, Limestone and Sedimentary Apatite in Columns for Phosphorus Removal from Sludge Fish Farm Effluents

    Directory of Open Access Journals (Sweden)

    Florent Chazarenc

    2010-08-01

    Full Text Available Laboratory scale studies have repeatedly reported high P-retention in slag, a by-product of the steel manufacturing industry. Thus, it has emerged as a potential material to increase P-removal from constructed wetlands (CWs. However, several limitations were highlighted by field experiments, including the high pH of treated water and clogging. We hypothesized that the addition of sedimentary rocks to slag would preserve P-removal properties while reducing the pH of treated water. Four 2.5 L-columns were filled with 100% apatite (column A; a 50% weight each mixture of limestone with apatite (column B; 10% steel slag located at the inlet, plus 45% limestone mixed with 45% apatite (column C; and a mixture of steel slag (10%, limestone (45% apatite (45% (column D. A synthetic effluent (26 mg P/L and a reconstituted sludge fish farm effluent containing 97 mg/L total suspended solids (TSS, 220 mg/L chemical oxygen demand (COD and 23.5 mg P/L phosphorus (P were applied sequentially during 373 and 176 days, under saturated flow conditions and 12–24 hours hydraulic residence time (HRT, respectively. Treatment performance, P-removal, pH and calcium (Ca2+ were monitored. Results indicated that columns that contained 10% weight steel slag resulted in a higher P retention capacity than the columns without steel slag. The highest P removal was achieved in column C, containing a layer of slag in the inlet zone, 45% apatite and 45% limestone. Feeding the columns with a reconstituted fish farm effluent led to biofilm development, but this had little effect on the P-removal. A combination of slag and sedimentary rocks represents a promising filtration material that could be useful downstream of CWs to further increase P-removal.

  3. Effects of UV-irradiation on in vitro apatite-forming ability of TiO2 layers

    International Nuclear Information System (INIS)

    Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone-tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone-tissue bonding, such as chemical treatment with H2O2 or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H2O2 chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO2 (anatase phase) layers as UV was irradiated under a few different conditions. TiO2 layer was prepared by the chemical treatment with H2O2 solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 deg. C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

  4. Effects of UV-irradiation on in vitro apatite-forming ability of TiO{sub 2} layers

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuki, Keita, E-mail: dns20353@s.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Nakashima Medical Co., Ltd., Joto-Kitagata, Higashi-ku, Okayama-shi 709-0625 (Japan); Kaneda, Haruki [Faculty of Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Shirosaki, Yuki [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Hayakawa, Satoshi [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Research Center for Biomedical Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Osaka, Akiyoshi, E-mail: a-osaka@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Research Center for Biomedical Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan)

    2010-10-15

    Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone-tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone-tissue bonding, such as chemical treatment with H{sub 2}O{sub 2} or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H{sub 2}O{sub 2} chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO{sub 2} (anatase phase) layers as UV was irradiated under a few different conditions. TiO{sub 2} layer was prepared by the chemical treatment with H{sub 2}O{sub 2} solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 deg. C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

  5. Experimental osteoinduction in rats: collagen-apatite versus osteogenin-containing gelatine.

    Science.gov (United States)

    Schwarz, N; Redl, H; Schlag, G; Lintner, F; Dinges, H P; Thurnher, M; Schiesser, A

    1987-01-01

    An experimental study in rats was done to investigate the bone-regenerating properties of collagen apatite (Collapat) and to compare it with osteoinduction dependent on osteogenin-containing gelatine (OCG). The test substances were implanted orthotopically (calvarial defect--7 mm in diameter) and heterotopically (paravertebral muscles, abdominal muscles). The results were evaluated histologically and enzymatically (alkaline phosphatase). Collapat caused neither osteoinduction in the heterotopic site nor healing of the bone defects. Foreign body reaction without new bone formation was encountered. OCG implantation leads to new bone formation in the muscles within 3 weeks, associated with a significant increase in alkaline phosphatase activity, and to extensive new bone formation in the calvarial defect within 4 weeks. The defects did not heal if left empty. The value of clinical application of Collapat appears to be doubtful. Osteoinduction with OCG requires further experimental investigation. PMID:3551878

  6. Study of cation-localisation in apatite and orthophosphate structures using 181Hf/181Ta probe

    International Nuclear Information System (INIS)

    Nuclear quadrupole interaction study using Time Differential Perturbed Angular Correlation technique has been carried out to identify the sites where hafnium can reside in hydroxyapatite in order to mimic the behavior of plutonium adsorption on hydroxyapatite. Hf(IV) has been found to occupy three sites with the quadrupole interaction frequency (ωQ) and its asymmetry (η): (i) ωQ = 136.7(5) Mrad/s, η = 0.54(1); (ii) ωQ 300.1(9) Mrad/s, η = 0.35(2); (iii) ωQ = 124.6(5), η = 0.0(1). Narrow frequency distributions indicate the sites are well-defined. This study has been extended to barium orthophosphate to confirm our inference for the apatite structure. (author)

  7. Effects of added ZnTCP on mechanical and biological properties of apatite cement

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, K.; Suzuki, K. [Okayama Univ. Dental School (Japan). Dept. of Biomaterials; Miyamoto, Y.; Toh, T.; Yuasa, T.; Nagayama, M. [Tokushima Univ. (Japan). First Dept. of Oral and Maxillofacial Surgery; Ito, A. [National Inst. for Advanced Interdisciplinary Research, MITT, Ibaragi (Japan)

    2001-07-01

    Effects of added Zn doped {beta}-tricalcium phosphate (ZnTCP) on mechanical and biological properties of apatite cement (AC) was studied. Powder X-ray diffractometer revealed that ZnTCP shows no reactivity with AC. The mechanical strength of AC decreased increasing amounts of added ZnTCP. We observed no effect on the setting time of AC when the amount of ZnTCP was 10% or less. Proliferation of the osteoblastic cells was significantly increased on the surface of AC containing 5% ZnTCP when compared with that containing no ZnTCP. In contrast, proliferation of the cells decreased on the surface of AC containing 10% ZnTCP when compared with that free from ZnTCP; indicating cytotoxity. We concluded therefore, that addition of ZnTCP to AC might be useful to enhance the osteoconductivity of AC when release of Zn{sup 2+} can be carefully regulated. (orig.)

  8. Strong correlation in 1D oxygen-ion conduction of apatite-type lanthanum silicate

    International Nuclear Information System (INIS)

    Oxygen-ion conduction in apatite-type lanthanum silicate, La9.33+0.67x(SiO4)6O2+x (x = 1), has theoretically been analyzed in a first-principles manner followed by the nudged elastic band method and the kinetic Monte Carlo method. Unlike the conventional cooperative interstitialcy mechanism along the single O4 columns, diffusing interstitial oxygen ions are frequently blocked by adjacent interstitial oxygen ions (Oint ions), leading to the strongly-correlated diffusivity and conductivity of oxygen ions in the case of chemical compositions with large x values. The getting-out mechanism from the O4 column is of importance in the long-range conduction, which temporarily transfers a part of Oint ions out of the columns to relax the blocking effect. The getting-out mechanism plays a key role also in the conduction perpendicular to the c axis (in the ab plane). (paper)

  9. Technology of production of high-level concentrate of rare earths from Kola apatite

    International Nuclear Information System (INIS)

    The procedure is described of separating rare earth elements from the Kola apatite which contains 0.7 to 1.0% oxides of rare earths. The separation takes place during the manufacture of combined fertilizer NPK-1. During the manufacture of the fertilizer the solution is neutralized with the precipitation of phosphates of rare earths. Increasing pH is accompanied by increased yield of the sum of rare earths. The yield is higher for lighter lanthanoids than for heavier lanthanoids. The phosphate concentrate is decomposed by nitric acid and rare earth elements are precipitated by oxalic acid. Following the annealing of the oxalate concentrate the obtained oxide concentrate will contain 92 to 95% oxides of rare earths. (E.S.)

  10. Mesozoic-Cenozoic thermal history of Turpan-Hami Basin: apatite fission track constraints

    Institute of Scientific and Technical Information of China (English)

    ZHU Wenbin; WAN Jinglin; SHU Liangshu; SUN Yan; GUO Jichun; WANG Feng

    2005-01-01

    Apatite fission track dating is carried out on nine samples collected from the central part (Lianmuqin section) and from both northern and southern margins of Turpan-Hami Basin. The fission-track ages of seven Jurassic samples are distinctly younger than depositional ages. In contrast, the fission-track ages of two Cretaceous samples are older than, or as old as depositional ages. These observations indicate that the Jurassic samples have been annealed or partially annealed, whereas the Cretaceous samples have not been annealed.The further thermal modelling results show that Turpan-Hami Basin experienced a Late Cretaceous period (120-100 Ma) of tectonic uplift with rapid cooling and exhumation of sediments. The samples underwent a Cenozoic period of reburial and re-heating and were exhumed again at 10-8 Ma.

  11. Contrasting histopathology and crystal deposits in kidneys of idiopathic stone formers who produce hydroxy apatite, brushite, or calcium oxalate stones.

    Science.gov (United States)

    Evan, Andrew P; Lingeman, James E; Worcester, Elaine M; Sommer, Andre J; Phillips, Carrie L; Williams, James C; Coe, Fredric L

    2014-04-01

    Our previous work has shown that stone formers who form calcium phosphate (CaP) stones that contain any brushite (BRSF) have a distinctive renal histopathology and surgical anatomy when compared with idiopathic calcium oxalate stone formers (ICSF). Here we report on another group of idiopathic CaP stone formers, those forming stone containing primarily hydroxyapatite, in order to clarify in what ways their pathology differs from BRSF and ICSF. Eleven hydroxyapatite stone formers (HASF) (2 males, 9 females) were studied using intra-operative digital photography and biopsy of papillary and cortical regions to measure tissue changes associated with stone formation. Our main finding is that HASF and BRSF differ significantly from each other and that both differ greatly from ICSF. Both BRSF and ICSF patients have significant levels of Randall's plaque compared with HASF. Intra-tubular deposit number is greater in HASF than BRSF and nonexistent in ICSF while deposit size is smaller in HASF than BRSF. Cortical pathology is distinctly greater in BRSF than HASF. Four attached stones were observed in HASF, three in 25 BRSF and 5-10 per ICSF patient. HASF and BRSF differ clinically in that both have higher average urine pH, supersaturation of CaP, and calcium excretion than ICSF. Our work suggests that HASF and BRSF are two distinct and separate diseases and both differ greatly from ICSF.

  12. Synchrotron Microanalytical Methods in the Study of Trace and Minor Elements in Apatite

    Energy Technology Data Exchange (ETDEWEB)

    Rakovan,J.; Luo, Y.; Borkiewicz, O.

    2008-01-01

    Synchrotron X-ray facilities have the capability for numerous microanalytical methods with spatial resolutions in the micron to submicron range and sensitivities as low as ppm to ppb. These capabilities are the result of a high X-ray brilliance (many orders of magnitude greater than standard tube and rotating anode sources); a continuous, or white, spectrum through the hard X-ray region; high degrees of X-ray columniation and polarization; and new developments in X-ray focusing methods. The high photon flux and pulsed nature of the source also allow for rapid data collection and high temporal resolution in certain experiments. Of particular interest to geoscientists are X-ray fluorescence microprobes which allow for numerous analytical techniques including X-ray fluorescence (XRF) analysis of trace element concentrations and distributions; X-ray absorption spectroscopy (XAS) for chemical speciation, structural and oxidation state information; X-ray diffraction (XRD) for phase identification; and fluorescence microtomography (CMT) for mapping the internal structure of porous or composite materials as well as elemental distributions. We have employed several synchrotron based microanalytical methods including XRF, microEXAFS (Extended X-ray Absorption Fine Structure), microXANES (X-ray Absorption Near Edge Structure) and CMT for the study of minor and trace elements in apatite (and other minerals). We have also been conducting time resolved X-ray diffraction to study nucleation of and phase transformations among precursor phases in the formation of apatite from solution at earth surface conditions. Summaries of these studies are given to exemplify the capabilities of synchrotron microanalytical techniques.

  13. Extraction and characterisation of apatite- and tricalcium phosphate-based materials from cod fish bones

    International Nuclear Information System (INIS)

    Apatite- and tricalcium phosphate-based materials were produced from codfish bones, thus converting a waste by-product from the food industry into high added-valued compounds. The bones were annealed at temperatures between 900 and 1200 °C, giving a biphasic material of hydroxyapatite and tricalcium phosphate (Ca10(PO4)6(OH)2 and β-Ca(PO4)3) with a molar proportion of 75:25, a material widely used in biomedical implants. The treatment of the bones in solution prior to their annealing changed the composition of the material. Single phase hydroxyapatite, chlorapatite (Ca10(PO4)6Cl2) and fluorapatite (Ca10(PO4)6F2) were obtained using CaCl2 and NaF solutions, respectively. The samples were analysed by several techniques (X-ray diffraction, infrared spectroscopy, scanning electron microscopy and differential thermal/thermogravimetric analysis) and by elemental analyses, to have a more complete understanding of the conversion process. Such compositional modifications have never been performed before for these materials of natural origin to tailor the relative concentrations of elements. This paper shows the great potential for the conversion of this by-product into highly valuable compounds for biomedical applications, using a simple and effective valorisation process. - Highlights: ► Apatite and calcium phosphate compounds extraction from cod fish bones ► Bone calcination: biphasic material hydroxyapatite-calcium phosphate production ► Bone pre-treatments in solution change the material composition. ► Single phase materials (hydroxy-, chloro- or fluoroapatite) are obtained. ► Concentration of other elements (Na, F, Cl) suitable for biomedical applications

  14. Ion microprobe U-Pb dating and REE abundance of biogenic apatite

    Science.gov (United States)

    Sano, Y.; Terada, K.; Ueki, S.

    2001-12-01

    If the direct U-Pb dating of a fossil itself is possible, the method could have great impact on stratigraphic studies in establishing the absolute chronology of sedimentary sequences. Micro fossil ?conodont? are candidates for this purpose since they consist of apatite (Ca2(PO5)3 (F,Cl,OH)), which would uptake U, Th and Pb after sedimentation no longer than a few million years and is supposed to remain closed to U and Pb under relatively low effective closure temperature. We report here results of direct ion microprobe U-Th-Pb dating of two conodonts; Trichognathus from Kinderhookian stage of Mississippian sedimentary sequence from Illinois Basin region in North America and Panderodus from a Llandoverian sedimentary sequence on Langkawi Island, northern Malaysia. Secondary purpose of the study is to indicate in situ analysis of all REE on the same spots of U-Pb measurements. Samples were cast into epoxy resin discs with a few grains of standard apatite, PRAP, derived from an alkaline rock of Prairie Lake circular complex in the Canadian Shield and polished until they were exposed through their mid-sections. U, Th and REE abundances, and Pb isotopic compositions were measured by using SHRIMP installed at Hiroshima University. Thirteen spots on Trichognathus yield a 238U/206Pb isochron age of 323+/-36 Ma, which is consistent with the depositional and early diagenetic ages. Fifteen spots on Panderodus give 232Th/208Pb isochron age of 429+/-50 Ma, which is again comparable to an early Silurian. Shale-normalized REE of Trichognathus shows a broadly flat pattern from light to middle REE and a decrease from middle to heavy REE with negative anomalies of Ce and Eu. In contrast Panderodus indicates a concave-shape pattern with middle REE enrichment. These characteristics are probably due to a different formation environment as suggested by other workers.

  15. Nanomedicine: Interaction of biomimetic apatite colloidal nanoparticles with human blood components.

    Science.gov (United States)

    Choimet, Maëla; Hyoung-Mi, Kim; Jae-Min, Oh; Tourrette, Audrey; Drouet, Christophe

    2016-09-01

    This contribution investigates the interaction of two types of biomimetic-apatite colloidal nanoparticles (negatively-charged 47nm, and positively-charged 190nm NPs) with blood components, namely red blood cells (RBC) and plasma proteins, with the view to inspect their hemocompatibility. The NPs, preliminarily characterized by XRD, FTIR and DLS, showed low hemolysis ratio (typically lower than 5%) illustrating the high compatibility of such NPs with respect to RBC, even at high concentration (up to 10mg/ml). The presence of glucose as water-soluble matrix for freeze-dried and re-dispersed colloids led to slightly increased hemolysis as compared to glucose-free formulations. NPs/plasma protein interaction was then followed, via non-specific protein fluorescence quenching assays, by contact with whole human blood plasma. The amount of plasma proteins in interaction with the NPs was evaluated experimentally, and the data were fitted with the Hill plot and Stern-Volmer models. In all cases, binding constants of the order of 10(1)-10(2) were found. These values, significantly lower than those reported for other types of nanoparticles or molecular interactions, illustrate the fairly inert character of these colloidal NPs with respect to plasma proteins, which is desirable for circulating injectable suspensions. Results were discussed in relation with particle surface charge and mean particle hydrodynamic diameter (HD). On the basis of these hemocompatibility data, this study significantly complements previous results relative to the development and nontoxicity of biomimetic-apatite-based colloids stabilized by non-drug biocompatible organic molecules, intended for use in nanomedicine. PMID:27137807

  16. Extraction and characterisation of apatite- and tricalcium phosphate-based materials from cod fish bones

    Energy Technology Data Exchange (ETDEWEB)

    Piccirillo, C.; Silva, M.F. [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Porto (Portugal); Pullar, R.C. [Dept. Engenharia de Materiais e Ceramica/CICECO, Universidade de Aveiro, Aveiro (Portugal); Braga da Cruz, I. [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Porto (Portugal); WeDoTech, CiDEB/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Porto (Portugal); Jorge, R. [WeDoTech, CiDEB/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Porto (Portugal); Pintado, M.M.E. [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Porto (Portugal); Castro, P.M.L., E-mail: plcastro@porto.ucp.pt [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Porto (Portugal)

    2013-01-01

    Apatite- and tricalcium phosphate-based materials were produced from codfish bones, thus converting a waste by-product from the food industry into high added-valued compounds. The bones were annealed at temperatures between 900 and 1200 Degree-Sign C, giving a biphasic material of hydroxyapatite and tricalcium phosphate (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2} and {beta}-Ca(PO{sub 4}){sub 3}) with a molar proportion of 75:25, a material widely used in biomedical implants. The treatment of the bones in solution prior to their annealing changed the composition of the material. Single phase hydroxyapatite, chlorapatite (Ca{sub 10}(PO{sub 4}){sub 6}Cl{sub 2}) and fluorapatite (Ca{sub 10}(PO{sub 4}){sub 6}F{sub 2}) were obtained using CaCl{sub 2} and NaF solutions, respectively. The samples were analysed by several techniques (X-ray diffraction, infrared spectroscopy, scanning electron microscopy and differential thermal/thermogravimetric analysis) and by elemental analyses, to have a more complete understanding of the conversion process. Such compositional modifications have never been performed before for these materials of natural origin to tailor the relative concentrations of elements. This paper shows the great potential for the conversion of this by-product into highly valuable compounds for biomedical applications, using a simple and effective valorisation process. - Highlights: Black-Right-Pointing-Pointer Apatite and calcium phosphate compounds extraction from cod fish bones Black-Right-Pointing-Pointer Bone calcination: biphasic material hydroxyapatite-calcium phosphate production Black-Right-Pointing-Pointer Bone pre-treatments in solution change the material composition. Black-Right-Pointing-Pointer Single phase materials (hydroxy-, chloro- or fluoroapatite) are obtained. Black-Right-Pointing-Pointer Concentration of other elements (Na, F, Cl) suitable for biomedical applications.

  17. Biogenic hydroxyapatite (Apatite II Trade-Mark-Sign ) dissolution kinetics and metal removal from acid mine drainage

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, J. [Department of Mining Engineering and Natural Resources, Politechnical University of Catalunya, Bases de Manresa 61-73, Manresa 08242, Catalonia (Spain); Cama, J., E-mail: jordi.cama@idaea.csic.es [Department of Geosciences, Institute of Environmental Assessment and Water Research, IDAEA, CSIC, Jordi Girona 18-26, Barcelona 08034, Catalonia (Spain); Cortina, J.L. [Department of Chemical Engineering, Politechnical University of Catalunya, Avinguda Diagonal 647, Barcelona 08028, Catalonia (Spain); Ayora, C. [Department of Geosciences, Institute of Environmental Assessment and Water Research, IDAEA, CSIC, Jordi Girona 18-26, Barcelona 08034, Catalonia (Spain); De Pablo, J. [Department of Chemical Engineering, Politechnical University of Catalunya, Avinguda Diagonal 647, Barcelona 08028, Catalonia (Spain)

    2012-04-30

    Apatite II Trade-Mark-Sign is a biogenic hydroxyapatite (expressed as Ca{sub 5}(PO{sub 4})OH) derived from fish bone. Using grains of Apatite II Trade-Mark-Sign with a fraction size between 250 and 500 {mu}m, batch and flow-through experiments were carried out to (1) determine the solubility constant for the dissolution reaction Ca{sub 5}(PO{sub 4}){sub 3}(OH) Left-Right-Double-Arrow 5Ca{sup 2+} + 3PO{sub 4}{sup 3-} + OH{sup -}, (2) obtain steady-state dissolution rates over the pH range between 2.22 and 7.14, and (3) study the Apatite II Trade-Mark-Sign 's mechanisms to remove Pb{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, and Cu{sup 2+} from metal polluted water as it dissolves. The log K{sub S} value obtained was -50.8 {+-} 0.82 at 25 Degree-Sign C. Far-from-equilibrium fish-bone hydroxyapatite dissolution rates decrease by increasing pH. Assuming that the dissolution reaction is controlled by fast adsorption of a proton on a specific surface site that dominates through the pH range studied, probably {identical_to}P-O{sup -}, followed by a slow hydrolysis step, the dissolution rate dependence is expressed in mol m{sup -2} s{sup -1} as Rate{sub 25 Degree-Sign C}=-8.9 Multiplication-Sign 10{sup -10} Multiplication-Sign (9.96 Multiplication-Sign 10{sup 5} Multiplication-Sign a{sub H{sup +}})/(1+9.96 Multiplication-Sign 10{sup 5} Multiplication-Sign a{sub H{sup +}}) where a{sub H{sup +}} is the proton activity in solution. Removal of Pb{sup 2+}, Zn{sup 2+}, Mn{sup 2+} and Cu{sup 2+} was by formation of phosphate-metal compounds on the Apatite II Trade-Mark-Sign substrate, whereas removal of Cd{sup 2+} was by surface adsorption. Increase in pH enhanced the removal of aqueous heavy metals. Using the kinetic parameters obtained (e.g., dissolution rate and pH-rate dependence law), reactive transport simulations reproduced the experimental variation of pH and concentrations of Ca, P and toxic divalent metal in a column experiment filled with Apatite II Trade-Mark-Sign that was

  18. Axion Crystals

    CERN Document Server

    Ozaki, Sho

    2016-01-01

    The low-energy effective theories for gapped insulators are classified by three parameters: permittivity $\\epsilon$, permeability $\\mu$, and theta angle $\\theta$. Crystals with periodic $\\epsilon$ are known as photonic crystals. We here study the band structure of photons in a new type of crystals with periodic $\\theta$ (modulo $2\\pi$) in space, which we call the axion crystals. We find that the axion crystals have a number of new properties that the usual photonic crystals do not possess, such as the helicity-dependent photonic band gaps and the nonrelativistic gapless dispersion relation at small momentum. We briefly discuss possible realizations of axion crystals in condensed matter systems as well as high-energy physics.

  19. Evidence for the exsolution of Cl-rich fluids in martian magmas: Apatite petrogenesis in the enriched lherzolitic shergottite Northwest Africa 7755

    Science.gov (United States)

    Howarth, G. H.; Pernet-Fisher, J. F.; Bodnar, R. J.; Taylor, L. A.

    2015-10-01

    Martian meteorite Northwest Africa 7755 is a new example of an enriched, lherzolitic shergottite, containing some of the coarsest-grained apatite yet identified in shergottite meteorites. Their size has permitted detailed observations of volatile distributions within single grains. We have demonstrated that some apatites have been invaded by shock melts, which act to devolatilize parts of grains, resulting in significant Cl-enrichment in the adjacent regions. The extent of chemical heterogeneity within single grains must be carefully considered in other shergottites, so that the effects of secondary modification of apatites are well-constrained, prior to interpreting the volatile contents and primary magmatic processes. Apatite grains unaffected by shock melts are OH-F enriched and Cl-poor (∼F50Cl14OH36), relative to interstitial apatites reported in other shergottites. The volatile compositions are similar to interstitial apatites reported in terrestrial mafic intrusions. Such apatites in terrestrial intrusions are argued to have formed after significant Cl-loss due to the exsolution and migration of Cl-rich brines. Calculated relative F2, Cl2, and H2O fugacities for NWA 7755 apatites show a trend of degassing rather than fractionation, noted in previous studies. Indeed, we interpret the volatile contents of apatites analyzed in the cumulate shergottite NWA 7755 to represent snapshots of the evolving late-stage residual liquid during exsolution of a Cl-rich brine. This fluid phase has subsequently been lost from an open magma system, migrating upward through the cumulate sequence enriching residual liquids in Cl. Alternatively, it formed a hydrothermal system in the martian crust surrounding the intrusion. Furthermore, by comparison with terrestrial examples, we suggest that the late-stage evolution of volatile-bearing phases in NWA 7755 is similar to that of comparable terrestrial mafic rocks. Primary cumulus apatites are F-rich, whereas interstitial apatites

  20. The role of prenucleation clusters in surface-induced calcium phosphate crystallization

    Science.gov (United States)

    Dey, Archan; Bomans, Paul H. H.; Müller, Frank A.; Will, Julia; Frederik, Peter M.; de With, Gijsbertus; Sommerdijk, Nico A. J. M.

    2010-12-01

    Unravelling the processes of calcium phosphate formation is important in our understanding of both bone and tooth formation, and also of pathological mineralization, for example in cardiovascular disease. Serum is a metastable solution from which calcium phosphate precipitates in the presence of calcifiable templates such as collagen, elastin and cell debris. A pathological deficiency of inhibitors leads to the uncontrolled deposition of calcium phosphate. In bone and teeth the formation of apatite crystals is preceded by an amorphous calcium phosphate (ACP) precursor phase. ACP formation is thought to proceed through prenucleation clusters-stable clusters that are present in solution already before nucleation-as was recently demonstrated for CaCO3 (refs 15,16). However, the role of such nanometre-sized clusters as building blocks for ACP has been debated for many years. Here we demonstrate that the surface-induced formation of apatite from simulated body fluid starts with the aggregation of prenucleation clusters leading to the nucleation of ACP before the development of oriented apatite crystals.

  1. Apatite/Melt Partitioning Experiments Reveal Redox Sensitivity to Cr, V, Mn, Ni, Eu, W, Th, and U

    Science.gov (United States)

    Righter, K.; Yang, S.; Humayun, M.

    2016-01-01

    Apatite is a common mineral in terrestrial, planetary, and asteroidal materials. It is commonly used for geochronology (U-Pb), sensing volatiles (H, F, Cl, S), and can concentrate rare earth elements (REE) during magmatic fractionation and in general. Some recent studies have shown that some kinds of phosphate may fractionate Hf and W and that Mn may be redox sensitive. Experimental studies have focused on REE and other lithophile elements and at simplified or not specified oxygen fugacities. There is a dearth of partitioning data for chalcophile, siderophile and other elements between apatite and melt. Here we carry out several experiments at variable fO2 to study the partitioning of a broad range of trace elements. We compare to existing data and then focus on several elements that exhibit redox dependent partitioning behavior.

  2. In situ Sr/Sr investigation of igneous apatites and carbonates using laser-ablation MC-ICP-MS

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.;

    2003-01-01

    In situ Sr isotopic compositions of coexisting apatite and carbonate for carbonatites from the Sarfartoq alkaline complex, Greenland, have been determined by laser-ablation multicollector inductively coupled plasma mass spectrometry. This study is the first to examine the extent of Sr isotopic...... (regional) scale open-system processes, possibly involving mixing of carbonatitic melts derived from distinct mantle sources or from a common isotopically heterogeneous mantle. Copyright © 2003 Elsevier Science Ltd....

  3. RNA Crystallization

    Science.gov (United States)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  4. Mineralization of HA crystals regulated by terephthaloyl chloride-modified silk fibroin films

    Institute of Scientific and Technical Information of China (English)

    Rong Li; Guang Mei Chen; Xin Lan Ma; Qiao Yan Chen; Ge Wen Xu; Yi Ping Huang

    2011-01-01

    Terephthaloyl chloride (DB)-modified silk fibroin (SF) films were immersed into 1.5 times simulated body fluid (1.5 SBF) to regulate the mineralization of hydroxyapatite (HA) crystals at about 36.5 ℃ for 24 h. UV was used to prove that the new bonds form between the DB and SF. The structure and morphology of the SF/HA were investigated by FTIR, ICP, XRD and SEM. The results showed that the apatite deposited on the matrix of SF mainly was HA. HA was self-assembled on the matrix of SF and formed three-dimensional framework when the weight ratio of DB/SF was 0.30. The content of DB affected the structure and morphology of the apatite composites deposited on the SF films.

  5. The structure, bond strength and apatite-inducing ability of micro-arc oxidized tantalum and their response to annealing

    Science.gov (United States)

    Wang, Cuicui; Wang, Feng; Han, Yong

    2016-01-01

    In this study, the tantalum oxide coatings were formed on pure tantalum (Ta) by micro-arc oxidation (MAO) in electrolytic solutions of calcium acetate and β-glycerophosphate disodium, and the effect of the applied voltage on the microstructure and bond strength of the MAO coatings was systematically investigated. The effect of annealing treatment on the microstructure, bond strength and apatite-inducing ability of the MAO coatings formed at 350 and 450 V was also studied. The study revealed that during the preparation of tantalum oxide coatings on Ta substrate by MAO, the applied voltage considerably affected the phase components, morphologies and bond strength of the coatings, but had little effect on surface chemical species. After annealing treatment, newly formed CaTa4O11 phase mainly contributed to the much more stronger apatite-inducing ability of the annealed tantalum oxide coatings than those that were not annealed. The better apatite-inducing ability of the MAO coatings formed at 450 V compared to those formed at 350 V was attributed to the less amorphous phase and more crystalline phase as well as more Ca and P contained in the MAO coatings with increasing the applied voltage.

  6. Ca L2,3-edge XANES and Sr K-edge EXAFS study of hydroxyapatite and fossil bone apatite

    Science.gov (United States)

    Zougrou, I. M.; Katsikini, M.; Brzhezinskaya, M.; Pinakidou, F.; Papadopoulou, L.; Tsoukala, E.; Paloura, E. C.

    2016-08-01

    Upon burial, the organic and inorganic components of hard tissues such as bone, teeth, and tusks are subjected to various alterations as a result of interactions with the chemical milieu of soil, groundwater, and presence of microorganisms. In this study, simulation of the Ca L 2,3-edge X-ray absorption near edge structure (XANES) spectrum of hydroxyapatite, using the CTM4XAS code, reveals that the different symmetry of the two nonequivalent Ca(1) and Ca(2) sites in the unit cell gives rise to specific spectral features. Moreover, Ca L 2,3-edge XANES spectroscopy is applied in order to assess variations in fossil bone apatite crystallinity due to heavy bacterial alteration and catastrophic mineral dissolution, compared to well-preserved fossil apatite, fresh bone, and geologic apatite reference samples. Fossilization-induced chemical alterations are investigated by means of Ca L 2,3-edge XANES and scanning electron microscopy (SEM) and are related to histological evaluation using optical microscopy images. Finally, the variations in the bonding environment of Sr and its preference for substitution in the Ca(1) or Ca(2) sites upon increasing the Sr/Ca ratio is assessed by Sr K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy.

  7. The Influence of Surface Morphology of Dense Ca-P Ceramics on Apatite Formation in Dynamic SBF

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This study aimed at exploring the effect of surface morphology of dense phosphate calcium (Ca-P) ceramics upon the formation of bone-like apatite in static or dynamic simulated body fluid (SBF). Dense and sandblasted calcium phosphate ceramics were immersed into dynamic SBF flowing at normal physiological speed of body fluid of skeletal muscle.The changes were characterized using SEM, XPS, IR and XRD. Changes can be observed after the sandblasted surface of dense calcium phosphate ceramics had been immersed in SBF for 14 days. XPS analysis results showed that the flake-like structure was composed of Ca, P, C, O; IR analysis result of surface structure of samples showed that there were specific peaks for CO2-3; XRD results indicated the decrease in crystallinity and the increase in amorphous structure. The rough surface was advantageous for the formation of bone-like apatite. Increasing the Ca2+, HPO2-4 concentration of SBF could also enhance the bone like apatite formation. All the results demonstrated that local concentration is a key factor affecting nucleation.

  8. Effect of geometrical structure on drug release rate of a three-dimensionally perforated porous apatite/collagen composite cement.

    Science.gov (United States)

    Otsuka, Makoto; Nakagawa, Hidenori; Ito, Atsuo; Higuchi, William I

    2010-01-01

    To improve the biocompatibility, inter-connective pore structure, and drug delivery ability of self-setting apatite/collagen composite cement (ACC), a three-dimensionally perforated porous apatite/collagen composite cement (TPPACC) containing 3% indomethacin (IMC) was obtained in an arranged multi-cross with 20, 40, and 60 stainless steel needlelike male dies, and stored and hardened at 37 degrees C and 100% relative humidity for 24 h. The mean radius of micro-pores of the TPPACC was evaluated to be 0.125 microm by mercury porosimetry. X-ray powder diffraction and FT-IR spectroscopy suggested that TPPACC consisted of carbonated apatite and had a structure similar to that of natural rat bone. The IMC release rates from a TPPACC block containing the drug were measured in simulated body fluid. The rate of release increased with the number of macro-pores that from planar surface matrix systems followed the Higuchi equation. The relationship between the Higuchi constant and surface area of TPPACC showed a straight line with K = 0.2123 and R(2) = 0.9892. These results indicated that the rate of drug release from TPPACC could be controlled by the number of macro-pores for bone cells. PMID:19821491

  9. Apatite ore mine tailings as an amendment for remediation of a lead-contaminated shooting range soil.

    Science.gov (United States)

    Venäläinen, Salla H

    2011-10-01

    This study investigated the use of tailings from apatite ore beneficiation in the remediation of a heavily contaminated shooting range soil. The tailings originating in Siilinjärvi carbonatite complex, Finland, consist of apatite residues accompanied by phlogopite and calcite. In a pot experiment, organic top layer of a boreal forest soil predisposed to pellet-derived lead (Pb) was amended with tailings of various particle-sizes (Ø>0.2mm, Ø<0.2mm and unsieved material) differing in their mineralogical composition. After 9-, 10-, 14- and 21-month incubation, the samples were monitored for tailings-induced changes in the different Pb pools by means of sequential fractionation. Following the incubation, the samples were extracted with water and the extracts were analyzed for Pb species distribution by means of a cation exchange resin. The results revealed that Pb was continuously released from the shotgun pellet fragments due to weathering. However, the apatite and calcite compartments in the tailings counteracted the mobility of the released Pb through the formation of sparingly soluble fluorpyromorphite and cerussite. Furthermore, the tailings efficiently reduced the bioavailability of Pb by transferring it from the water-soluble and exchangeable pools into the organic one. The material also increased the proportion of the less toxic non-cationic Pb to the total dissolved Pb from the initial level of 5% to 9-12%. The results suggest that the tailings-induced stabilization of Pb may be an environmentally sound remediation technique at polluted sites. PMID:21871651

  10. Conodont apatite δ18O signatures indicate climatic cooling as a trigger of the Late Devonian mass extinction

    Science.gov (United States)

    Joachimski, Michael M.; Buggisch, Werner

    2002-08-01

    The oxygen isotopic composition of conodont apatite from two Frasnian-Famennian boundary sections was measured in order to reconstruct variations in marine paleotemperatures during the late Frasnian mass-extinction event. The measured conodont apatite δ18O values reveal two positive excursions with maximum amplitudes of +1‰ to +1.5‰ that parallel positive excursions in the carbonate carbon isotopic composition. The +3‰ excursions in carbonate δ13C have been interpreted as consequences of enhanced organic carbon burial rate resulting in a decrease in atmospheric CO2 concentration. Climatic cooling as a potential consequence of lower atmospheric CO2 concentration is confirmed by the conodont apatite δ18O records, which translate into cooling of low-latitude surface waters by 5 7 °C. Repeated cooling of the low latitudes during the late Frasnian had a severe impact on the tropical shallow-water faunas that were probably adapted to warm surface-water temperatures and severely affected during the late Frasnian crisis. These prominent variations in ocean-water temperature were stressful to the tropical shallow-water fauna and potentially culminated in low origination rates of new species, one of the major factors of the decline in diversity during the latest Frasnian.

  11. Protein Crystallization

    Science.gov (United States)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  12. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed.

  13. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. PMID:26792536

  14. Intra-articular apatite deposition in mixed connective tissue disease: crystallographic and technetium scanning characteristics.

    OpenAIRE

    Hutton, C W; Maddison, P J; Collins, A J; Berriman, J A

    1988-01-01

    An acute arthritis in a patient with mixed connective tissue disease (MCTD) was found to be associated with intra-articular deposition of carbonated hydroxyapatite crystals. A technetium hydroxymethylene diphosphonate bone scan showed intense uptake in the delayed phase scan of the affected joints. Synovial fluid analysis demonstrated uptake of the radiopharmaceutical drug directly onto the crystals.

  15. Prediction of yttrium, lanthanum, cerium, and neodymium leaching recovery from apatite concentrate using artificial neural networks

    Institute of Scientific and Technical Information of China (English)

    E. Jorjani; A.H. Bagherieh; Sh. Mesroghli; S. Chehreh Chelgani

    2008-01-01

    The assay and recovery of rare earth elements (REEs) in the leaching process is being determined using expensive analytical methods: inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). A neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, and neodymium recovery in the leaching of apatite concentrate is presented in this article. The effects of leaching time (10 to 40 min),pulp densities (30% to 50%), acid concentrations (20% to 60%), and agitation rates (100 to 200 r/min), were investigated and optimized on the recovery of REEs in the laboratory at a leaching temperature of 60οC. The obtained data in the laboratory optimization process were used for training and testing the neural network. The feed-forward artificial neural network with a 4-5-5-1 arrangement was capable of estimating the leaching recovery of REEs. The neural network predicted values were in good agreement with the experimental results. The correlations of R=1 in training stages, and R=0.971, 0.952, 0.985, and 0.98 in testing stages were a result of Ce, Nd, La, and Y recovery prediction respectively, and these values were usually acceptable. It was shown that the proposed neural network model accurately reproduced all the effects of the operation variables, and could be used in the simulation of a leaching plant for REEs.

  16. Prompt isothermal decay of thermoluminescence in an apatite exhibiting strong anomalous fading

    Energy Technology Data Exchange (ETDEWEB)

    Sfampa, I.K. [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124 Thessaloniki (Greece); Polymeris, G.S. [Aristotle University of Thessaloniki, Solid State Physics Section, 54124 Thessaloniki (Greece); Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, ‘Athena’ R. and I. Center, Kimmeria University Campus, GR67100 Xanthi (Greece); Tsirliganis, N.C. [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, ‘Athena’ R. and I. Center, Kimmeria University Campus, GR67100 Xanthi (Greece); Pagonis, V. [McDaniel College, Physics Department, Westminster, MD 21157 (United States); Kitis, G., E-mail: gkitis@auth.gr [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124 Thessaloniki (Greece)

    2014-02-01

    Highlights: • The Isothermal TL of a material exhibiting strong AF is very peculiar. • The Isothermal TL curves are very well fitted using a newly proposed tunneling model. • The decay constants are found to be independent on temperature. • The explanation requires tunneling recombination from different excited energy levels. -- Abstract: Anomalous fading (AF) is one of the most serious drawbacks in thermoluminescence (TL) and optically stimulated luminescence (OSL) dating. In the present work the isothermal decay of TL signals from Durango apatite is studied for temperatures located on the rising part of the main TL peak. This material is known to exhibit strong AF phenomena, and its isothermal TL decay properties have not been studied previously. The experimental results show that the characteristic decay time of the isothermal signal does not depend of the temperature, and that this signal does not exhibit the strong temperature dependence expected from conventional TL kinetic theories. This is further direct experimental evidence for the possible presence of tunneling phenomena in this material. The isothermal decay curves are analyzed and discussed within the framework of conventional theories of TL, as well as within the context of a recently developed tunneling kinetic model for random distributions of electron-hole pairs in luminescent materials.

  17. Osteointegration of biomimetic apatite coating applied onto dense and porous metal implants in femurs of goats.

    Science.gov (United States)

    Barrère, F; van der Valk, C M; Meijer, G; Dalmeijer, R A J; de Groot, K; Layrolle, P

    2003-10-15

    Biomimetic calcium phosphate (Ca-P) coatings were applied onto dense titanium alloy (Ti6Al4V) and porous tantalum (Ta) cylinders by immersion into simulated body fluid at 37 degrees C and then at 50 degrees C for 24 h. As a result, a homogeneous bone-like carbonated apatitic (BCA) coating, 30 microm thick was deposited on the entire surface of the dense and porous implants. Noncoated and BCA-coated implants were press-fit implanted in the femoral diaphysis of 14 adult female goats. Bone contact was measured after implantation for 6, 12, and 24 weeks, and investigated by histology and backscattered electron microscopy (BSEM). After 6 weeks, bone contact of the BCA-coated Ti6Al4V implants was about 50%. After 12 and 24 weeks, bone contact was lower in comparison with the 6-week implantations at, respectively 24 and 39%. Regarding the BCA-coated porous Ta implants, bone contacts were 17, 30, and 18% after 6, 12, and 24 weeks, respectively. However, bone contact was always found significantly higher for BCA-coated dense Ti6Al4V and porous Ta cylinders than the corresponding noncoated implants. The results of this study show that the BCA coating enhances the bone integration as compared to the noncoated implants. PMID:14528464

  18. Fabrication and Physical Evaluation of Gelatin-Coated Carbonate Apatite Foam

    Directory of Open Access Journals (Sweden)

    Kanae Hara

    2016-08-01

    Full Text Available Carbonate apatite (CO3Ap foam has gained much attention in recent years because of its ability to rapidly replace bone. However, its mechanical strength is extremely low for clinical use. In this study, to understand the potential of gelatin-reinforced CO3Ap foam for bone replacement, CO3Ap foam was reinforced with gelatin and the resulting physical characteristics were evaluated. The mechanical strength increased significantly with the gelatin reinforcement. The compressive strength of gelatin-free CO3Ap foam was 74 kPa whereas that of the gelatin-reinforced CO3Ap foam, fabricated using 30 mass % gelatin solution, was approximately 3 MPa. Heat treatment for crosslinking gelatin had little effect on the mechanical strength of the foam. The gelatin-reinforced foam did not maintain its shape when immersed in a saline solution as this promoted swelling of the gelatin; however, in the same conditions, the heat-treated gelatin-reinforced foam proved to be stable. It is concluded, therefore, that heat treatment is the key to the fabrication of stable gelatin-reinforced CO3Ap foam.

  19. Constraining the stepwise migration of the eastern Tibetan Plateau margin by apatite fission track thermochronology

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing mod- eling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history mod- eling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study sug- gests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and conse- quently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.

  20. Constraining the stepwise migration of the eastern Tibetan Plateau margin by apatite fission track thermochronology

    Institute of Scientific and Technical Information of China (English)

    LAI QingZhou; DING Lin; WANG HongWei; YUE YaHui; CAI FuLong

    2007-01-01

    Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing modeling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history modeling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study suggests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and consequently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.

  1. Rare earth elements in Solnhofen biogenic apatite: geochemical clues to the palaeoenvironment

    Science.gov (United States)

    Kemp, Richard A.; Trueman, Clive N.

    2003-01-01

    Rare earth element (REE) concentrations in biogenic apatite samples (coprolite, bone and soft-tissue) were used to investigate the environment of deposition of the celebrated Solnhofen fossil Lagerstätten. The measured REE patterns are similar between different localities, lithologies (flinz, fäule) and levels in the Upper Solnhofen Plattenkalk, suggestive of a stable REE supply during deposition. The behaviour of cerium in the Solnhofen samples implies that bottom water conditions were not anoxic, and variations in the cerium anomaly can be explained by differences in burial rate. These results provide further geochemical support for current depositional models [Barthel, K.W., 1978. Solnhofen: Ein Blick in die Erdgeschichte. Ott Verlag, Thun.; Barthel, K.W., Swinburne, N.H.M., Conway Morris, S., 1990, Solnhofen. A Study in Mesozoic Palaeontology. Cambridge Univ. Press, Cambridge.] that propose that extra-basinal processes are responsible for the interbedded nature of the Solnhofen deposits, rather than intra-basinal processes such as water turnover events.

  2. Novel development of carbonate apatite-chitosan scaffolds based on lyophilization technique for bone tissue engineering

    Directory of Open Access Journals (Sweden)

    Maretaningtias Dwi Ariani

    2012-09-01

    Full Text Available Background: The natural biopolymer chitosan (Ch is currently regarded as a candidate for bone tissue engineering. However, Ch is poor for cell adhesion and low bone formation ability. In order to enhance cell adhesion and bone formation ability, combination of Ch with carbonate apatite (CA was developed. Purpose: The aim of this study was to make carbonate apatite-chitosan scaffolds (CAChSs and evaluate its osteoconductivity in terms of cell proliferation. Methods: Chitosan scaffolds (ChSs were made by the following procedure. Twenty-five, 50, 100, 200 and 400 mg Ch was dissolved into 5 ml of 2% acetic acid (CH3COOH, shaked for 15 min and neutralized with 15 ml of 0.1 M sodium hydroxide (NaOH solution. After centrifugation, Ch gel was packed into the molds then frozen at -80°C for 2h and dried in a freeze dry machine for 24h. The sponges were subjected to UV radiation for 2h. To make CA-ChSs, 200 mg Ch was selected. After neutralization, 50 mg of 0.06 M CA were added into the 200 mg Ch gel. The structure of CA-ChSs was observed by scanning electron microscope (SEM. Mouse osteoblast-like cell (MC3T3-E1 proliferation in these scaffolds was investigated at 1, 7, 14 and 21 days. Results: Three dimensional porous structures of CA-ChSs were clearly observed by SEM. Proliferated cell numbers in CA-ChSs was significantly higher than those in ChSs (control at each stage (p<0.05. Conclusion: It can be concluded that newly developed CA-ChSs had three-dimensional interconnected porous structure, good handling property and supporting ability of proliferation of osteoblasts. It is suggested that newly developed CA-ChSs could be considered as a scaffolds material for bone tissue enginearing.Latar belakang: Kitosan yang merupakan biopolimer alami dianggap sebagai salah satu kandidat untuk rekayasa jaringan tulang. Namun, kitosan memiliki kelemahan terhadap adhesi sel dan kurang mampu membentuk tulang yang cukup. Untuk meningkatkan adhesi sel dan kemampuan

  3. Ni(II immobilization by bio-apatite materials: Appraisal of chemical, thermal and combined treatments

    Directory of Open Access Journals (Sweden)

    Šljivić-Ivanović Marija

    2016-01-01

    Full Text Available Animal bones are natural and rich source of calcium hydroxyapatite (HAP, which was found to be a good sorbent material for heavy metals and radionuclides. Various treatments can reduce the content of bone organic phase and improve sorption properties. In this study, sorption capacities of raw bovine bones (B and samples obtained by chemical treatment with NaOH (BNaOH, by heating at 400 oC (B400 and by combined chemical and thermal treatment (BNaOH+400, were compared, using Ni(II ions as sorbates. Maximum sorption capacities increased in the order Bapatite based material with low organic content and high efficiency for Ni(II sorption, it is also a good candidate for in-situ soil remediation, particularly at lower contamination levels. [Projekat Ministarstva nauke Republike Srbije, br. III 43009

  4. Preferential orientation of biological apatite in normal and osteoporotic human vertebral trabeculae

    Science.gov (United States)

    Miyabe, S.; Ishimoto, T.; Nakano, T.

    2009-05-01

    The preferential orientation of biological apatite (BAp) is a possible bone quality parameter for the comparison of the bone mechanical property. The preferential BAp orientation undergoes sensitive changes according to the change in the in vivo stress distribution, bone turnover rate etc., resulting in a variation of bone function. Osteoporosis is a metabolic bone disease characterized by reduced bone mass and deterioration of bone microstructure. The effect of osteoporosis on the preferential BAp orientation is however unknown. In this study, a microbeam-X-ray diffraction (μXRD) study was carried out on a trabecula extracted from osteoporotic and normal human vertebral bones and the degree of orientation for the BAp c-axis along its craniocaudal axis was analysed based on our previous report. A micro-computed tomography (μCT) measurement was also performed to analyze trabecular density and structure. In osteoporotic human vertebra, the trabecular number is markedly lower than that in normal vertebra. To sustain increased stress because of bone loss, the primary trabeculae, which are aligned parallel to the craniocaudal axis, tend to selectively remain while the secondary trabeculae, which are perpendicular to the craniocaudal axis, mostly disappear. Moreover, the primary trabecula from osteoporotic vertebra showed a significantly higher degree of BAp preferential orientation than the normal bone. This suggests that the remaining primary trabecula in osteoporotic vertebra is further reinforced by an increase in applied stress in vivo by enhancing the preferred BAp c-axis orientation along the trabecular direction.

  5. Prompt isothermal decay of thermoluminescence in an apatite exhibiting strong anomalous fading

    International Nuclear Information System (INIS)

    Highlights: • The Isothermal TL of a material exhibiting strong AF is very peculiar. • The Isothermal TL curves are very well fitted using a newly proposed tunneling model. • The decay constants are found to be independent on temperature. • The explanation requires tunneling recombination from different excited energy levels. -- Abstract: Anomalous fading (AF) is one of the most serious drawbacks in thermoluminescence (TL) and optically stimulated luminescence (OSL) dating. In the present work the isothermal decay of TL signals from Durango apatite is studied for temperatures located on the rising part of the main TL peak. This material is known to exhibit strong AF phenomena, and its isothermal TL decay properties have not been studied previously. The experimental results show that the characteristic decay time of the isothermal signal does not depend of the temperature, and that this signal does not exhibit the strong temperature dependence expected from conventional TL kinetic theories. This is further direct experimental evidence for the possible presence of tunneling phenomena in this material. The isothermal decay curves are analyzed and discussed within the framework of conventional theories of TL, as well as within the context of a recently developed tunneling kinetic model for random distributions of electron-hole pairs in luminescent materials

  6. Crystal Data

    Science.gov (United States)

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  7. Selective inhibition of crystal growth on octacalcium phosphate and nonstoichiometric hydroxyapatite by pyrophosphate at physiological concentration

    Science.gov (United States)

    Eidelman, N.; Brown, W. E.; Meyer, J. L.

    1991-09-01

    Octacalcium phosphate, Ca 8H 2(PO 4) 6·5H 2O (OCP), appears to be a precursor in biomineral formation. The formation of OCP as the precursor is supported by the observation that stoichiometric hydroxyapatite, Ca 5(PO 4) 3OH (OHAp), cannot form directly because of the presence of its growth inhibitors in serum. Therefore, the effects of the physiological concentration of pyrophosphate (P 2O 4-7), one of the most important calcium phosphate growth inhibitors in blood, on calcium phosphate growth rates on OCP and nonstoichiometric OHAp (apatite) seeds were measured. The amounts of seed crystals used to initiate the growth were adjusted by trial and error so that the control growth rates (in the absence of P 2O 4-7) were the same on both OCP and apatite seeds at a given supersaturation. The crystal growth on both kinds of seed crystals from supersaturated solutions in the presence of 1μM P 2O 4-7 added once ("one-time" addition) at constant pH (7.4) and 25°C was determined by KOH titration and decreases in Ca and PO 4 concentrations in the solutions. Crystal growth on OCP seed crystals in the presence of a constant concentration of 1μM P 2O 4-7 was also measured. The growing phases were characterized by ‡Ca/‡PO 4 ratios, chemical potential plots, X-ray diffraction (XRD) and Fourier transform infrared (FTIR). The results of this study show that: (1) P 2O 4-7 ions inhibited the growth on the apatite seeds more than on the OCP seeds; (2) apparently OCP precipitated on both types of seeds, followed by its hydrolysis to a more apatite-like phase; (3) slower crystal growth was observed on OCP seeds in the presence of a constant physiological concentration of P 2O 4-7 (1μM) than in the "one-time" addition of P 2O 4-7.

  8. Equilibrium partitioning and subsequent re-distribution of halogens among apatite-biotite-amphibole assemblages from mantle-derived plutonic rocks: Complexities revealed

    Science.gov (United States)

    Teiber, Holger; Scharrer, Manuel; Marks, Michael A. W.; Arzamastsev, Andrei A.; Wenzel, Thomas; Markl, Gregor

    2015-04-01

    The concentration of halogens in apatite, biotite and amphibole is investigated for a large variety of mantle-derived plutonic rocks (gabbros, diorites, monzonites, olivine- and pyroxene-bearing monzonitic to granitic rocks, syenites, carbonatites and a phoscorite). In all rocks studied, apatite occurs as an early magmatic phase, whereas biotite and amphibole may occur either as a late magmatic phase or as late-stage, potentially hydrothermal product replacing precursor olivine, pyroxene and Fe-Ti oxides (ilmenite and magnetite). Based on electron microprobe analyses for F and Cl and detailed textural observations, we test existing models of halogen partitioning between apatite and biotite. Bromine concentration data for apatite, biotite and amphibole are used to further refine our understanding of the geochemical similarities and differences between Cl and Br during magmatic and hydrothermal processes. Our data suggests that F and Cl contents in apatite, biotite and amphibole can indeed be useful monitors of the halogen systematics in magmas, but they may also be subject to post-magmatic changes to variable extents. The relatively small radius and compatible F cation seems to be less prone to post-magmatic alteration and is likely to best reflect the original magmatic halogen abundances - especially in apatite. However, the larger and probably more incompatible Cl anion, is more easily re-mobilized as reflected by strong redistribution of Cl in biotite and amphibole which have been clearly overprinted by hydrothermal fluids. In certain cases, the ability of halogens to re-distribute themselves after magmatic equilibrium partitioning (as emphasized by our data) suggests that observed partitioning (especially between apatite and biotite) may also be used as a very sensitive indicator for post-magmatic hydrothermal processes.

  9. Surface or internal nucleation and crystallization of glass-ceramics

    Science.gov (United States)

    Höland, W.; Rheinberger, V. M.; Ritzberger, C.; Apel, E.

    2013-07-01

    Fluoroapatite (Ca5(PO4)3F) was precipitated in glass-ceramics via internal crystallization of base glasses. The crystals grew with a needle-like morphology in the direction of the crystallographic c-axis. Two different reaction mechanisms were analyzed: precipitation via a disordered primary apatite crystals and a solid state parallel reaction to rhenanite (NaCaPO4) precipitation. In contrast to the internal nucleation used in the formation of fluoroapatite, surface crystallization was induced to precipitate a phosphate-free oxyapatite of NaY9(SiO4)6O2-type. Internal nucleation and crystallization have been shown to be a very useful tool for developing high-strength lithium disilicate (Li2Si2O5) glass-ceramics. A very controlled process was conducted to transform the lithium metasilicate glass-ceramic precursor material into the final product of the lithium disilicate glass-ceramic without the major phase of the precursor material. The combination of all these methods allowed the driving forces of the internal nucleation and crystallization mechanisms to be explained. An amorphous phosphate primary phase was discovered in the process. Nucleation started at the interface between the amorphous phosphate phase and the glass matrix. The final products of all these glass-ceramics are biomaterials for dental restoration showing special optical properties, e.g. translucence and color close to dental teeth.

  10. Crystallization of nuclear glass under a thermal gradient: application to the self-crucible produced in the skull melting process

    International Nuclear Information System (INIS)

    In the context of the vitrification of high level nuclear waste, a new industrial process has been launched in 2010 at the La Hague factory: The skull melting process. This setup applies thermal gradients to the melt, which leads to the formation of a solid layer of glass: the 'self-crucible'. The question would be to know whether these thermal gradients have an impact or not on the crystallization behaviour of the considered glasses in the self crucible. In order to answer that question, the crystallization of two glass compositions of nuclear interest has been investigated with an image analysis based method in isothermal and thermal gradient heat treatments conditions. The isothermal experiments allow for the quantification (growth speed, nucleation, crystallized fraction) of the crystallization of apatites (660 C-900 C) and powellites (630 C-900 C). The comparison of the results obtained through these two types of experimentations allows us to conclude that there is no impact of the thermal gradient on the crystallization of the studied glass compositions. In order to complete the image analysis study (based on surfaces), in and ex situ microtomography experiments have been performed at ESRF (Grenoble) on the ID19 beamline. This study allowed us to follow the crystallization of apatites in a simplified glass and to confirm the reliability of the image analysis method based on the analysis of surfaces. (author)

  11. Strategies for the optimisation of the oxide ion conductivities of apatite-type germanates

    Energy Technology Data Exchange (ETDEWEB)

    Orera, A.; Slater, P.R. [School of Chemistry, University of Birmingham, Birmingham (United Kingdom); Baikie, T. [School of Materials Science and Engineering, Nanyang Technological University, Singapore (Singapore); Panchmatia, P.; Islam, M.S. [Department of Chemistry, University of Bath, Bath (United Kingdom); White, T.J. [Centre for Advanced Microscopy, Australian National University, Canberra ACT 2601 (Australia); Hanna, J.; Smith, M.E. [Department of Physics, University of Warwick, Coventry (United Kingdom); Kendrick, E. [Chemical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2011-02-15

    Recently, apatite-type germanates La{sub 9.33+x}Ge{sub 6}O{sub 26+3x/2} have attracted considerable interest due to their high oxide ion conductivities. Research has shown that the key defects are oxide ion interstitials which lead to the conversion of some of the GeO{sub 4} units to GeO{sub 5}. Consequently there has been a large interest in the preparation of high oxygen excess samples with high defect concentration. This strategy, however, leads to a reduction in symmetry from hexagonal to triclinic for x> 0.4, and consequently to reduced oxide ion conductivity at low temperatures. We present doping strategies to stabilise the hexagonal lattice, while maintaining high oxygen content. In particular, partial substitution of La by smaller rare earths (Y,Yb) is shown to be successful in preparing x = 0.67 samples with hexagonal symmetry and hence high conductivities. In addition, doping on the Ge site with Ti, Nb or W, has been shown to be similarly successful, leading to very high oxygen contents for W doping, e.g. La{sub 10}Ge{sub 5.5}W{sub 0.5}O{sub 27.5}. In the case of Ti doping, however, there was some evidence for trapping of the interstitial oxide ions around the Ti. Preliminary results on the effect of similar doping strategies on Pr, Nd germanates (Pr/Nd){sub 9.33+x}Ge{sub 6}O{sub 26+3x/2}, are also discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Biological Behavior of Osteoblast Cell and Apatite Forming Ability of the Surface Modified Ti Alloys.

    Science.gov (United States)

    Zhao, Jingming; Hwang, K H; Choi, W S; Shin, S J; Lee, J K

    2016-02-01

    Titanium as one kind of biomaterials comes in direct contact with the body, making evaluation of biocompatibility an important aspect to biomaterials development. Surface chemistry of titanium plays an important role in osseointegration. Different surface modification alters the surface chemistry and result in different biological response. In this study, three kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coating successfully formed on the Ti surfaces in simulated body fluid. Strong mixed acid increased the roughness of the metal surface, because the porous and rough surface allows better adhesion between Ca-P coatings and substrates. After modification of titanium surface by mixed acidic solution and subsequently H2O2/HCL treatment evaluation of biocompatibility was conducted from hydroxyapatite formation by biomimetic process and cell viability on modified titanium surface. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Results from this study indicated that surface treatment methods affect the surface morphology, type of TiO2 layer formed and subsequent apatite deposition and biological responses. The thermo scientific alamarblue cell viability assay reagent is used to quantitatively measure the viability of mammalian cell lines, bacteria and fungi by incorporating a rapid, sensitive and reliable fluorometric/colorimetric growth indicator, without any toxic and side effect to cell line. In addition, mixed acid treatment uses a lower temperature and shorter time period than widely used alkali treatment. PMID:27433617

  13. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron;

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium.......We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  14. Project Work Plan: Sequestration of Strontium-90 Subsurface Contamination in the Hanford 100-N Area by Surface Infiltration of an Apatite Solution

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, Jim E.

    2006-04-30

    We propose to develop an infiltration strategy that defines the precipitation rate of an apatite-forming solution and Sr-90 sequestration processes under variably saturated (low water content) conditions. We will develop this understanding through small-scale column studies, intermediate-scale two-dimensional (2-D) experiments, and numerical modeling to quantify individual and coupled processes associated with apatite formation and Sr-90 transport during and after infiltration of the Ca-citrate-PO4 solution. Development of capabilities to simulate these coupled biogeochemical processes during both injection and infiltration will be used to determine the most cost-effective means to emplace an in situ apatite barrier with a longevity of 300 years to permanently sequester Sr-90 until it decays. Biogeochemical processes that will be investigated are citrate biodegradation and apatite precipitation rates at varying water contents as a function of water content. Coupled processes that will be investigated include the influence of apatite precipitation (which occupies pore space) on the hydraulic and transport properties of the porous media during infiltration.

  15. Enhanced ionic conductivity of apatite-type lanthanum silicate electrolyte for IT-SOFCs through copper doping

    Science.gov (United States)

    Ding, Xifeng; Hua, Guixiang; Ding, Dong; Zhu, Wenliang; Wang, Hongjin

    2016-02-01

    Apatite-type Lanthanum silicate (LSO) is among the most promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs) owing to the high conductivity and low activation energy at lower temperature than traditional doped-zirconia electrolyte. The ionic conductivity as well as the sintering density of lanthanum silicate oxy-apatite, La10Si6-xCuxO27-δ (LSCO, 0 ≤ x ≤ 2), was effectively enhanced through a small amount of doped copper. The phase composition, relative density, ionic conductivity and thermal expansion behavior of La10Si6-xCuxO27-δ was systematically investigated by X-ray diffraction (XRD), Archimedes' drainage method, scanning electron microscope (SEM), electrochemical impedance spectra (EIS) and thermal dilatometer techniques. With increasing copper doping content, the ionic conductivity of La10Si6-xCuxO27-δincreased, reaching a maximum of 4.8 × 10-2 S cm-1 at 800 °C for x = 1.5. The improved ionic conductivity could be primarily associated with the enhanced grain conductivity. The power output performance of NiO-LSCO/LSCO/LSCF single cell was superior to that obtained on NiO-LSO/LSO/LSCF at different temperatures using hydrogen as fuel and oxygen as oxidant, which could be attributed to the enhanced oxygen ionic conductivity as well as the sintering density for the copped doped lanthanum silicate. In conclusion, the apatite La10Si4.5Cu1.5O25.5 is a promising candidate electrolyte for IT-SOFCs.

  16. Apatite Fission Track Analysis of Sites 959 and 960 on the Transform Continental Margin of Ghana, West Africa

    OpenAIRE

    A. Carter; Clift, P. D.; Hurford, A.J.

    1998-01-01

    Four samples of sandstone from deformed Aptian–Albian sediments and their less deformed Turonian cover at Sites 959 and 960 on the Côte d’Ivoire-Ghana Marginal Ridge yielded sufficient apatite for fission track analysis. Reduced mean track length values of 12.42 ± 0.16 μm to 13.67 ± 0.11 μm indicate that measured central ages, which range from 88 ± 4 Ma to 113 ± 4 Ma, have undergone partial resetting and are therefore apparent ages. Stochastic modeling of the fission track age and le...

  17. Exhumations- und Hebungsgeschichte der zentralen Anden in Südbolivien (21°S) durch Spaltspur-Thermochronologie an Apatit

    OpenAIRE

    Ege, Harald

    2010-01-01

    The Tertiary formation of the Altiplano-Puna plateau at the active continental margin of South America resulted in the doubling of the crust and surface uplift by about 4000 m. The aim of this study is to reconstruct the Tertiary cooling and exhumation history by apatite fission track thermochronology (AFT) and hence to characterise the processes which produced plateau uplift. The study area follows a transect at 21°S in Southern Bolivia across the plateau and the eastern flank of the Andes. ...

  18. Abundance and distribution of uranium and thorium in zircon, sphene, apatite, epidote, and monazite in granitic rocks

    Science.gov (United States)

    Hurley, Patrick M.; Fairbairn, Harold W.

    1956-01-01

    Analyses were made of uranium and thorium in ziircon, sphene, apatite, epidote, and monazite separated as accessory minerals from samples of granitic rock from widely scattered localities to indicate the abundance and distribution of these two elements among the five mineral phases.  For any pair of mineral phases the distribution ratio remains within the same order of magnitude over the different rocks tested, although the variability of the data is such that only wide departures from constancy could be ascertained.  Such gross differences have not been found. 

  19. Renal histopathology and crystal deposits in patients with small bowel resection and calcium oxalate stone disease.

    Science.gov (United States)

    Evan, Andrew P; Lingeman, James E; Worcester, Elaine M; Bledsoe, Sharon B; Sommer, Andre J; Williams, James C; Krambeck, Amy E; Philips, Carrie L; Coe, Fredric L

    2010-08-01

    We present here the anatomy and histopathology of kidneys from 11 patients with renal stones following small bowel resection, including 10 with Crohn's disease and 1 resection in infancy for unknown cause. They presented predominantly with calcium oxalate stones. Risks of formation included hyperoxaluria (urine oxalate excretion greater than 45 mg per day) in half of the cases, and acidic urine of reduced volume. As was found with ileostomy and obesity bypass, inner medullary collecting ducts (IMCDs) contained crystal deposits associated with cell injury, interstitial inflammation, and papillary deformity. Cortical changes included modest glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Randall's plaque (interstitial papillary apatite) was abundant, with calcium oxalate stone overgrowth similar to that seen in ileostomy, idiopathic calcium oxalate stone formers, and primary hyperparathyroidism. Abundant plaque was compatible with the low urine volume and pH. The IMCD deposits all contained apatite, with calcium oxalate present in three cases, similar to findings in patients with obesity bypass but not an ileostomy. The mechanisms for calcium oxalate stone formation in IMCDs include elevated urine and presumably tubule fluid calcium oxalate supersaturation, but a low calcium to oxalate ratio. However, the mechanisms for the presence of IMCD apatite remain unknown.

  20. Application of carbonated apatite coating on a Ti substrate by aqueous spray method

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Chihiro; Hara, Hiroki [Division of Liberal Arts, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo 192-0015 (Japan); Takano, Ichiro [Department of Electrical Engineering, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo 192-0015 (Japan); Hayakawa, Tohru [Department of Dental Engineering, Tsurumi University School of Dental Medicine, Tsurumi, Yokohama City, Kanagawa 230-8501 (Japan); Sato, Mitsunobu, E-mail: lccsato@cc.kogakuin.ac.jp [Division of Liberal Arts, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo 192-0015 (Japan)

    2013-03-01

    The fabrication and characterization of a carbonate-containing apatite film deposited on a Ti plate via an aqueous spray method is described. The mist of the spray solution emitted from a perpendicularly oriented airbrush was made to strike a warmed Ti substrate. The thicknesses of the sprayed film and those heat-treated at 400 Degree-Sign C-700 Degree-Sign C under Ar gas flow were in the range 1.21-1.40 {mu}m. The results of elemental analyses and Fourier transform infrared spectroscopy of the powders that were mechanically collected from the surface of the sprayed film suggest that the film was Ca{sub 10}(PO{sub 4})6(CO{sub 3}) {center_dot} 2CO{sub 2} {center_dot} 3H{sub 2}O. The presence of the carbonate ion and the lattice CO{sub 2} molecule was confirmed via the aforementioned analyses; the finding was also consistent with the X-ray diffraction patterns of the films and the chemical identity of the sprayed and heat-treated films that were measured using X-ray photoelectron spectroscopy. The sprayed film comprises a characteristic network structure, which contains round particles within the networks, as was observed by field-emission scanning electron microscopy. A scratch test indicated that the shear stress of the sprayed film (21 MPa) significantly improved to 40 and > 133 MPa after heat-treatment at 600 Degree-Sign C and 700 Degree-Sign C, respectively, under Ar gas flow for 10 min. - Highlights: Black-Right-Pointing-Pointer CO{sub 2} inserted CA films were fabricated on a Ti plate by the aqueous spray method. Black-Right-Pointing-Pointer The characteristic network structure of the sprayed film was clarified by FE-SEM. Black-Right-Pointing-Pointer Ca{sub 10}(PO{sub 4})6(CO{sub 3}) {center_dot} 2CO{sub 2} {center_dot} 3H{sub 2}O film with a thickness of ca. 1 {mu}m could be deposited. Black-Right-Pointing-Pointer A well-adhered film with shear stress of 21 MPa was obtained at low temperatures. Black-Right-Pointing-Pointer A stable solution for VOC

  1. Application of carbonated apatite coating on a Ti substrate by aqueous spray method

    International Nuclear Information System (INIS)

    The fabrication and characterization of a carbonate-containing apatite film deposited on a Ti plate via an aqueous spray method is described. The mist of the spray solution emitted from a perpendicularly oriented airbrush was made to strike a warmed Ti substrate. The thicknesses of the sprayed film and those heat-treated at 400 °C–700 °C under Ar gas flow were in the range 1.21–1.40 μm. The results of elemental analyses and Fourier transform infrared spectroscopy of the powders that were mechanically collected from the surface of the sprayed film suggest that the film was Ca10(PO4)6(CO3) · 2CO2 · 3H2O. The presence of the carbonate ion and the lattice CO2 molecule was confirmed via the aforementioned analyses; the finding was also consistent with the X-ray diffraction patterns of the films and the chemical identity of the sprayed and heat-treated films that were measured using X-ray photoelectron spectroscopy. The sprayed film comprises a characteristic network structure, which contains round particles within the networks, as was observed by field-emission scanning electron microscopy. A scratch test indicated that the shear stress of the sprayed film (21 MPa) significantly improved to 40 and > 133 MPa after heat-treatment at 600 °C and 700 °C, respectively, under Ar gas flow for 10 min. - Highlights: ► CO2 inserted CA films were fabricated on a Ti plate by the aqueous spray method. ► The characteristic network structure of the sprayed film was clarified by FE-SEM. ► Ca10(PO4)6(CO3) · 2CO2 · 3H2O film with a thickness of ca. 1 μm could be deposited. ► A well-adhered film with shear stress of 21 MPa was obtained at low temperatures. ► A stable solution for VOC-free spraying was facilely prepared.

  2. Apatite Fission-Track Analysis of the Middle Jurassic Todos Santos Formation from Chiapas, Mexico.

    Science.gov (United States)

    Abdullin, Fanis; Solé, Jesús; Shchepetilnikova, Valentina; Solari, Luigi; Ortega-Obregón, Carlos

    2014-05-01

    The Sierra de Chiapas (SCH), located in the south of Mexico, is a complex geological province that can be divided on four different lithological or tectonic areas: (1) the Chiapas Massif Complex (CMC); (2) the Central Depression; (3) the Strike-slip Fault Province, and (4) the Chiapas Fold-and-thrust Belt. The CMC mostly consists of Permian granitoids and meta-granitoids, and represents the basement of the SCH. During the Jurassic period red beds and salt were deposited on this territory, related to the main pulse of rifting and opening of the Gulf of Mexico. Most of the Cretaceous stratigraphy contains limestones and dolomites deposited on a marine platform setting during the postrift stage of the Gulf of Mexico rift. During the Cenozoic Era took place the major clastic sedimentation along the SCH. According the published low-temperature geochronology data (Witt et al., 2012), SCH has three main phases of thermo-tectonic history: (1) slow exhumation between 35 and 25 Ma, that affected mainly the basement (CMC) and is probably related to the migration of the Chortís block; (2) fast exhumation during the Middle-Late Miocene caused by strike-slip deformation that affects almost all Chiapas territory; (3) period of rapid cooling from 6 to 5 Ma, that affects the Chiapas Fold-and-thrust Belt, coincident with the landward migration of the Caribbean-North America plate boundaries. The two last events were the most significant on the formation of the present-day topography of the SCH. However, the stratigraphy of the SCH shows traces of the existence of earlier tectonic events. This study presents preliminary results of apatite fission-track (AFT) dating of sandstones from the Todos Santos Formation (Middle Jurassic). The analyses are performed with in situ uranium determination using LA-ICP-MS (e.g., Hasebe et al., 2004). The AFT data indicate that this Formation has suffered high-grade diagenesis (probably over 150 ºC) and the obtained cooling ages, about 70-60 Ma

  3. 100-NR-2 Apatite Treatability Test: Fall 2010 Tracer Infiltration Test (White Paper)

    Energy Technology Data Exchange (ETDEWEB)

    Vermeul, Vincent R.; Fritz, Brad G.; Fruchter, Jonathan S.; Greenwood, William J.; Johnson, Timothy C.; Horner, Jacob A.; Strickland, Christopher E.; Szecsody, James E.; Williams, Mark D.

    2011-04-14

    change and the associated change in moisture content so that 4D images of moisture content change can be generated. Results from this field test will be available for any future Ca-citrate-PO4 amendment infiltration tests, which would be designed to evaluate the efficacy of using near surface application of amendments to form apatite mineral phases in the upper portion of the zone of water table fluctuation.

  4. Synthesis of some calcium phosphate crystals using the useful biomass for immobilization of microorganisms

    Science.gov (United States)

    Kohiruimaki, T.

    2011-10-01

    Three sources of biomass generated by primary industry were used as the raw material for the synthesis of calcium phosphate crystals. Phosphoric acid was extracted from burned rice chaff using a 30% nitric acid solution, while scallop shells and gypsum of plasterboard were used as calcium sources. The calcium phosphate crystals were synthesized by a method involving homogeneous precipitation, and the relationship between the composition and shape of the crystals and the pH at the time of the precipitation was investigated. Monetite crystals in a petal form with a diameter ranging from 0.1 to 2 μm were precipitated at pH 2.0, while granular apatite crystals with a mean diameter of 1 μm were precipitated at pH 6.0. We also investigated the ability of the synthesized calcium phosphate crystals to immobilize lactic acid bacteria for practical use in industrial bioreactor. It was determined that monetite crystals with a diameter of 2 μm had the highest ability to fix lactic acid bacteria. The population of lactic acid bacteria was estimated to exceed 1,300 bacteria per crystal surface of 50 μm2 suggesting that these crystals may be of practical use in industrial fermenters.

  5. Synthesis of some calcium phosphate crystals using the useful biomass for immobilization of microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Kohiruimaki, T, E-mail: kohi@hi-tech.ac.jp [Department of Technology, Hachinohe Institute of Technology, 88-1 Myo-oobiraki, Hachinohe-shi 031-8501 (Japan)

    2011-10-29

    Three sources of biomass generated by primary industry were used as the raw material for the synthesis of calcium phosphate crystals. Phosphoric acid was extracted from burned rice chaff using a 30% nitric acid solution, while scallop shells and gypsum of plasterboard were used as calcium sources. The calcium phosphate crystals were synthesized by a method involving homogeneous precipitation, and the relationship between the composition and shape of the crystals and the pH at the time of the precipitation was investigated. Monetite crystals in a petal form with a diameter ranging from 0.1 to 2 {mu}m were precipitated at pH 2.0, while granular apatite crystals with a mean diameter of 1 {mu}m were precipitated at pH 6.0. We also investigated the ability of the synthesized calcium phosphate crystals to immobilize lactic acid bacteria for practical use in industrial bioreactor. It was determined that monetite crystals with a diameter of 2 {mu}m had the highest ability to fix lactic acid bacteria. The population of lactic acid bacteria was estimated to exceed 1,300 bacteria per crystal surface of 50 {mu}m{sup 2} suggesting that these crystals may be of practical use in industrial fermenters.

  6. Liquid Crystals

    Science.gov (United States)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  7. Radiation-damage-controlled He diffusion and 4He/3He spectra in apatite: an example of mutually consistent results from the Grand Canyon (Invited)

    Science.gov (United States)

    Farley, K. A.; Flowers, R. M.

    2009-12-01

    Recent work indicates that He diffusion from apatite is impeded by the accumulation of radiation damage from actinide decay. Supporting evidence includes laboratory diffusion measurements as well as (U-Th)/He dates positively correlated with effective uranium (eU) concentration in certain geologic situations. Here we investigate whether the radiation damage effect can be identified in 4He concentration profiles, as it must be if the system behaves as we anticipate. Apatites from nearby igneous basement samples in the Upper Gorge of the Grand Canyon showing a strong date-eU correlation were proton irradiated, step-heated, and analyzed for 4He/3He spectra. The low eU apatites with younger He dates yielded nearly flat spectra, while the high eU apatites with older He dates yielded highly rounded spectra (see Figure). This implies that the higher eU apatites were partially retaining He while the lower eU apatites were still acting as an open system. Using the RDAAM kinetic model (Flowers et al. 2009) and local geologic constraints we confirm that this behavior is consistent with the observed differences in date and eU, providing compelling evidence that both the He dates and the 4He profiles are sensitive to radiation damage accumulation. Equally importantly, the combination of multiple samples with differing eU and thus differing 4He/3He spectra yields remarkably tight constraints on the time-temperature path experienced by these rocks, from ~90oC down to < 30oC.

  8. The thermal history of the Miocene Ibar Basin (Southern Serbia: new constraints from apatite and zircon fission track and vitrinite reflectance data

    Directory of Open Access Journals (Sweden)

    Andrić Nevena

    2015-02-01

    Full Text Available The Ibar Basin was formed during Miocene large scale extension in the NE Dinaride segment of the Alpine- Carpathian-Dinaride system. The Miocene extension led to exhumation of deep seated core-complexes (e.g. Studenica and Kopaonik core-complex as well as to the formation of extensional basins in the hanging wall (Ibar Basin. Sediments of the Ibar Basin were studied by apatite and zircon fission track and vitrinite reflectance in order to define thermal events during basin evolution. Vitrinite reflectance (VR data (0.63-0.90 %Rr indicate a bituminous stage for the organic matter that experienced maximal temperatures of around 120-130 °C. Zircon fission track (ZFT ages indicate provenance ages. The apatite fission track (AFT single grain ages (45-6.7 Ma and bimodal track lengths distribution indicate partial annealing of the detrital apatites. Both vitrinite reflectance and apatite fission track data of the studied sediments imply post-depositional thermal overprint in the Ibar Basin. Thermal history models of the detritial apatites reveal a heating episode prior to cooling that began at around 10 Ma. The heating episode started around 17 Ma and lasted 10-8 Ma reaching the maximum temperatures between 100-130 °C. We correlate this event with the domal uplift of the Studenica and Kopaonik cores where heat was transferred from the rising warm footwall to the adjacent colder hanging wall. The cooling episode is related to basin inversion and erosion. The apatite fission track data indicate local thermal perturbations, detected in the SE part of the Ibar basin (Piskanja deposit with the time frame ~7.1 Ma, which may correspond to the youngest volcanic phase in the region.

  9. Formation of interconnected macropores in apatitic calcium phosphate bone cement with the use of an effervescent additive.

    Science.gov (United States)

    Hesaraki, S; Moztarzadeh, F; Sharifi, D

    2007-10-01

    Calcium phosphate cements (CPCs) can be considered as good candidate for bone tissue engineering because they can be resorbed and take part in the bone remodeling process. Several efforts have been made into improve the resorption rate of the calcium phosphate cement by introducing macropores to the cement matrix. In this investigation a simple and effective method has been presented based on the addition of various amounts of an effervescent agent to the calcium phosphate cement components. The effervescent agent was a mixture of sodium hydrogen carbonate, NaHCO(3) (that was added to the powder phase), and citric acid monohydrate, C(6)H(8)O(7).H(2)O (that was dissolved in the liquid phase). The obtained macroporous samples were characterized by Fourier transform infrared spectrometer, X-ray diffraction, and scanning electron microscopy techniques at 4 h after setting and 3 days after soaking in a special simulated body fluid solution named Hank's balanced salt solution. Mercury intrusion porosimetry was also employed for characterizing the pore volume and pore size distribution in the cement structure. Results showed that the rate of conversion of staring reactant to the apatite phase and the apatite chemistry were significantly changed by using the additive in the cement components. Also both the pore volume and pore size were changed by varying both the amount of effervescent additive and the powder to liquid ratio. PMID:17380498

  10. Multiple cooling episodes in the Central Tarim (Northwest China) revealed by apatite fission track analysis and vitrinite reflectance data

    Science.gov (United States)

    Chang, Jian; Qiu, Nansheng; Song, Xinying; Li, Huili

    2016-06-01

    Apatite fission track and vitrinite reflectance are integrated for the first time to study the cooling history in the Central Tarim, northwest China. The paleo-temperature profiles from vitrinite reflectance data of the Z1 and Z11 wells showed a linear relationship with depth, suggesting an approximately 24.8 °C/km paleo-geothermal gradient and 2700-3900 m of erosion during the Early Mesozoic. The measured apatite fission track ages from well Z2 in the Central Tarim range from 39 to 159 Ma and effectively record the Meso-Cenozoic cooling events that occurred in Central Tarim. Moreover, two cooling events at 190-140 Ma in the Early Jurassic-Early Cretaceous and 80-45 Ma in the Late Cretaceous-Paleocene revealed by measured AFT data and thermal modeling results are related to the collisions of the Qiangtang-Lhasa terranes and the Greater India Plate with the southern margin of the Eurasian Plate, respectively. This study provides new insights into the tectonic evolution of the Tarim Basin (and more broadly Central Asia) and for hydrocarbon generation and exploration in the Central Tarim.

  11. In vitro biomimetic deposition of apatite on alkaline and heat treated Ti6Al4V alloy surface

    Indian Academy of Sciences (India)

    K Fatehi; F Moztarzadeh; M Solati-Hashjin; M Tahriri; M Rezvannia; R Ravarian

    2008-04-01

    Titanium alloy (Ti6Al4V) substrates, having the ability of biomimetic calcium phosphate-based materials, especially hydroxyapatite deposition in a simulated body fluid (SBF) means of chemical treatment (alkaline treatment) and subsequent heat treatment, was studied. The effects of alkaline treatment time, concentration and heat treatment temperature on the formation of calcium phosphate (carbonate–hydroxyapatite) on Ti6Al4V surface were examined. For this purpose, the metallic substrates were treated in 0, 5 and 10 M NaOH solutions at a temperature of 60 or 80°C for 1 and 3 days. Subsequently the substrate was heat-treated at 500, 600 and 700°C for 1 h for consolidation of the sodium titanate hydrogel layer. Finally, they were soaked in SBF for 1 and 3 days. The substrate surfaces were characterized by the techniques commonly used for bulk material such as scanning electron microscopy (SEM) and thin film X-ray diffraction (TF–XRD). With regard to the SEM and TF–XRD results, the optimum process consists of 3 days soaking in 5 M NaOH in 80°C and subsequent heat treatment at 600°C for 1h. It is worth mentioning that the results showed that the apatite formed within 3 days on the specimen surfaces, however, there was no sign of apatite formation in the control samples (without alkaline and heat treatment) which was treated for up to 3 days immersion in SBF.

  12. Photonic crystals

    CERN Document Server

    Busch, Kurt; Wehrspohn, Ralf B; Föll, Helmut

    2006-01-01

    The majority of the contributions in this topically edited book stems from the priority program SPP 1113 ""Photonische Kristalle"" run by the Deutsche Forschungsgemeinschaft (DFG), resulting in a survey of the current state of photonic crystal research in Germany. The first part of the book describes methods for the theoretical analysis of their optical properties as well as the results. The main part is dedicated to the fabrication, characterization and modeling of two- and three-dimensional photonic crystals, while the final section presents a wide spectrum of applications: gas sensors, micr

  13. Properties and crystallization phenomena in Li2Si2O5-Ca5(PO43F and Li2Si2O5-Sr5(PO43F glass-ceramics via twofold internal crystallization

    Directory of Open Access Journals (Sweden)

    Markus eRampf

    2015-09-01

    Full Text Available The combination of specific mechanical, esthetic and chemical properties is decisive for the application of materials in prosthodontics. Controlled twofold crystallization provides a powerful tool to produce special property combinations for glass-ceramic materials. The present study outlines the potential of precipitating Ca5(PO43F as well as Sr5(PO43F as minor crystal phases in Li2Si2O5 glass-ceramics. Base glasses with different contents of CaO/SrO, P2O5 and F- were prepared within the glasses of the SiO2-Li2O-K2O-CaO/SrO-Al2O3-P2O5 system. Preliminary studies of nucleation by means of XRD and SEM of the nucleated base glasses revealed X-ray amorphous phase separation phenomena. Qualitative and quantitative crystal phase analyses after crystallization were conducted using XRD in combination with Rietveld refinement. As a main result, a direct proportional relationship between the content of apatite-forming components in the base glasses and the content of apatite in the glass ceramics was established. The microstructures of the glass-ceramics were investigated using SEM. Microstructural and mechanical properties were found to be dominated by Li2Si2O5 crystals and quite independent of the content of the apatite present in the glass-ceramics. Biaxial strengths of up to 540 MPa were detected. Ca5(PO43F and Sr5(PO43F influence the translucency of the glass-ceramics and hence, help to precisely tailor the properties of Li2Si2O5 glass-ceramics. The authors conclude that the twofold crystallization of Li2Si2O5-Ca5(PO43F or Li2Si2O5-Sr5(PO43F glass-ceramics involves independent solid state reactions which can be controlled via the chemical composition of the base glasses. The influence of the minor apatite phase on the optical properties helps to achieve new combinations of features of the glass-ceramics and hence, displays new potential for dental applications.

  14. Photonic crystals principles and applications

    CERN Document Server

    Gong, Qihuang

    2013-01-01

    IntroductionPrimary Properties of Photonic CrystalsFabrication of Photonic CrystalsPhotonic Crystal All-Optical SwitchingTunable Photonic Crystal FilterPhotonic Crystal LaserPhotonic Crystal Logic DevicesPhotonic Crystal Sensors

  15. Abrasive wear behaviour of bio-active glass ceramics containing apatite

    Indian Academy of Sciences (India)

    I Sevim; M K Kulekci

    2006-06-01

    In this study, abrasive wear behaviour of bio-active glass ceramic materials produced with two different processes is studied. Hot pressing process and conventional casting and controlled crystallization process were used to produce bio-active ceramics. Fracture toughness of studied material was calculated by fracture toughness equations using experimental hardness results of the bio-active glass ceramic material. Two fracture toughness equations in the literature were used to identify the wear behaviour of studied ceramics. Wear resistance results that identified with both of the equations were similar. The results showed that the abrasive wear resistance of the bio-active glass ceramics produced with hot pressing process was found to be higher than that of the ceramics produced by conventional casting and controlled crystallization process.

  16. Stable Isotope Analyses of Phosphate Oxygen From Micro-samples of Biological Apatite: A new Routine Procedure for Silverphosphate Micro-precipitation and the Removal of Organic Contamination

    Science.gov (United States)

    Wiedemann-Bidlack, F. B.; Colman, A. S.; Fogel, M. L.

    2003-12-01

    Oxygen isotope analyses in bone and teeth of living and fossil animals are widely used for testing hypotheses about variability of diet and habitat. For the analysis of environmental or dietary changes in the past, tooth enamel has become the preferred study material, because its mineral content is higher than bone and dentine, and the relatively large size of the carbonato-apatite crystals of enamel make it more stable against post mortem diagenetic alteration than dentine or bone. Intra-tooth sampling of dental enamel is increasingly used for the investigation of seasonal climate variability, taking advantage of both the high correlation between an animal's drinking water and the δ 18O in its mineralized tissues and the incremental growth pattern of tooth enamel. The different oxygen-containing ions of bioapatite (phosphate, carbonate, and hydroxyl group) incorporate into the mineral lattice at different rates during enamel mineralization, and differ in their susceptibility against post mortem diagenetic alteration. In addition, it is difficult to account for the different reaction chemistries of phosphate, carbonate, and hydroxyl group using isotope analysis techniques that include all oxygen contained in the enamel (e.g., laser ablation). These problems can be addressed analyzing phosphate oxygen only. However, two major factors limit the potential of δ 18O analyses in dental enamel: A) the starting sample size for isotope analyzes often precludes the use of small teeth or the intra-tooth sampling of a given tooth; B) Small amounts of biogenic organic material in tooth enamel (less than 1% by wt) can reduce the precision and lead to anomalous analytical results in δ 18O measurements on Ag3PO4 produced from tooth enamel. A new procedure was developed for the pre-treatment and δ 18O analysis of phosphate from small samples (500 μ g) of tooth enamel containing organic matter. Ag3PO{4} was precipitated quantitatively for analysis of δ 18Ophosphate using a

  17. Quantifying glacial erosion in the European Alps using apatite fission track dating

    Science.gov (United States)

    Wangenheim, Cornelia; Glotzbach, Christoph

    2015-04-01

    To investigate the impact of glacial erosion on landscape evolution during the Quaternary, problems may occur in choosing the best method, because many methods only reflect parts of the era. Erosion rate calculations based on cosmogenic nuclides only cover the Holocene and erosion rate calculations based on river load gauging reflect even shorter timescales (e.g. von Blanckenburg 2005). In this study we investigate the potential of thermochronological methods, especially apatite fission track dating (AFT) to quantify glacial erosion in the European Alps. The topography of the European Alps is strongly influenced by Quaternary glaciations, as it formed characteristic features like overdeepened and hanging valleys. The study area is located in the Central Alps of Switzerland, which is a high mountain area. At ~0.9 Ma glacial erosion has led to a considerable increase in valley incision rates in this area (Haeuselmann et al. 2007) and therefore it is ideally suited to study the glacial impact on landscape evolution. The advantage of using AFT dating, while studying changes in erosional processes, is that possibly arising nonsteady-state erosion will be recorded within the spatial distribution of thermochronological ages. In this study we applied AFT dating on both bedrock and sediments. The bedrock samples derive from different elevations to figure out whether or not spatial differences and elevation dependencies exist. Combined with already published data we have a relatively high sample density distributed throughout the whole study area. The detrital samples originate from stream sediments and from glacial deposits in the form of late glacial moraines and cave sediments from the last ~0.5 Ma in order to obtain possible lateral variations in erosion. The AFT ages of the bedrocks vary between ~4 Ma and ~9 Ma, resulting in an average long-term exhumation rate of ~0.5 km/Ma. Most of the ages range between 7 and 9 Ma, confirmed by prevailing ages of stream sediment

  18. Hypothesis of Lithocoding: Origin of the Genetic Code as a "Double Jigsaw Puzzle" of Nucleobase-Containing Molecules and Amino Acids Assembled by Sequential Filling of Apatite Mineral Cellules.

    Science.gov (United States)

    Skoblikow, Nikolai E; Zimin, Andrei A

    2016-05-01

    The hypothesis of direct coding, assuming the direct contact of pairs of coding molecules with amino acid side chains in hollow unit cells (cellules) of a regular crystal-structure mineral is proposed. The coding nucleobase-containing molecules in each cellule (named "lithocodon") partially shield each other; the remaining free space determines the stereochemical character of the filling side chain. Apatite-group minerals are considered as the most preferable for this type of coding (named "lithocoding"). A scheme of the cellule with certain stereometric parameters, providing for the isomeric selection of contacting molecules is proposed. We modelled the filling of cellules with molecules involved in direct coding, with the possibility of coding by their single combination for a group of stereochemically similar amino acids. The regular ordered arrangement of cellules enables the polymerization of amino acids and nucleobase-containing molecules in the same direction (named "lithotranslation") preventing the shift of coding. A table of the presumed "LithoCode" (possible and optimal lithocodon assignments for abiogenically synthesized α-amino acids involved in lithocoding and lithotranslation) is proposed. The magmatic nature of the mineral, abiogenic synthesis of organic molecules and polymerization events are considered within the framework of the proposed "volcanic scenario". PMID:27048216

  19. Evidence for Rapid Post-Pliocene Exhumation of the Santa Monica Mountains, California, from Apatite (U-Th)/He Thermochronometry

    Science.gov (United States)

    Niemi, N. A.; Clark, M. K.; Yakovlev, P. V.

    2015-12-01

    Potential losses related to large earthquakes on blind or previously unrecognized thrust faults is of significant concern to southern California, where numerous individual mountain ranges are underlain by active faults. Some of the most hazardous thrust fault systems in Southern California are associated with high-slip-rate faults in the northern portion of the western Transverse Ranges, while the southern region is generally considered to be less seismically active. Determining slip rates on faults bounding the Santa Monica Mountains has been challenging, in part because many of the faults that underlie the range have submarine surface traces. Existing geologic studies predict that these faults slip relatively slowly; however, recent GPS models predict a band of relatively fast contraction on faults that lie beneath the Santa Monica Mountains (Marshall et al., 2013). These geodetic models suggest unrecognized hazard associated with shortening and vertical uplift of this range. Late Cenozoic strata in the central Santa Monica Mountains are of sufficient thickness to bury Cretaceous and Paleocene strata above the closure temperature for apatite (U-Th)/He thermochronometry (~70°C). As a result, these older rocks, now exposed in the southern Santa Monica Mountains, may record exhumation associated with fault slip and associated structural deformation of the range. Preliminary apatite (U-Th)/He ages near Las Flores Canyon span from 3.5 to 6.5 Ma, and are the youngest apatite (U-Th)/He ages we are aware of in southern California outside of the transpressional San Andreas system. When plotted as depth beneath the base of the marine Modelo Formation, an inflection in age/depth gradient at 4 Ma is inferred to reflect the onset of fault motion and is consistent with the late Miocene age of the Modelo Formation. Based on average geothermal gradients for the Ventura and Los Angeles basins and an assumed thrust fault dip of 20°, observed apparent exhumation rates are

  20. A novel simple strategy for in situ deposition of apatite layer on AZ31B magnesium alloy for bone tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Mousa, Hamouda M. [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Engineering Materials and Mechanical Design, Faculty of Engineering, South Valley University, Qena 83523 (Egypt); Lee, Do Hee [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Park, Chan Hee, E-mail: biochan@jbnu.ac.kr [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2015-10-01

    Graphical abstract: - Highlights: • Anodizing process was used for the surface modification of AZ31B magnesium alloy. • An appetite-like film was deposited on the surface of AZ31B magnesium alloy. • Ceramic film was investigated by XRD and XPS. • Nano-plates growth are observed though the implemented experimental design. • Significant increase in the substrate hardness and surface roughness was observed. - Abstract: In this study, for the first time, the degradation performance of AZ31B Mg alloy was tuned by an in situ deposition of apatite thin layer within a short time in one step. Using Taguchi method for experimental design, anodization process was designed under control conditions (time and voltage), and simulated body fluid (SBF) was used as the electrolyte to nucleate apatite-like compounds. The coated alloy was characterized through field emission scanning electron microscopy (FE-SEM), EDS, X-ray diffraction and XPS analysis. The results show that the applied voltage has a significant effect on the formation of apatite-like layers. Compared to the uncoated samples, microhardness and surface roughness of the coated samples showed remarkably different values. The potentiodynamic polarization results demonstrate that the polarization resistance of the anodized samples is higher than the substrate polarization resistance, thus improving the alloy corrosion resistant. Based on the experimental results, the proposed nanostructure apatite-like coating can offer a promising way to improve the biocompatibility and degradability properties of the Mg alloy for bone tissue regeneration.

  1. Interim Report: 100-NR-2 Apatite Treatability Test: Low Concentration Calcium Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mark D.; Fritz, Brad G.; Mendoza, Donaldo P.; Rockhold, Mark L.; Thorne, Paul D.; Xie, YuLong; Bjornstad, Bruce N.; Mackley, Rob D.; Newcomer, Darrell R.; Szecsody, James E.; Vermeul, Vincent R.

    2008-07-11

    Following an evaluation of potential Sr-90 treatment technologies and their applicability under 100-NR-2 hydrogeologic conditions, U.S. Department of Energy, Fluor Hanford, Inc., Pacific Northwest National Laboratory, and the Washington Department of Ecology agreed that the long-term strategy for groundwater remediation at 100-N Area will include apatite sequestration as the primary treatment, followed by a secondary treatment if necessary (most likely phytoremediation). Since then, the agencies have worked together to agree on which apatite sequestration technology has the greatest chance of reducing Sr-90 flux to the river at a reasonable cost. In July 2005, aqueous injection, (i.e., the introduction of apatite-forming chemicals into the subsurface) was endorsed as the interim remedy and selected for field testing. Studies are in progress to assess the efficacy of in situ apatite formation by aqueous solution injection to address both the vadose zone and the shallow aquifer along the 300 ft of shoreline where Sr-90 concentrations are highest. This report describes the field testing of the shallow aquifer treatment.

  2. Structure and Thermal Expansion of Calcium-Thorium Apatite, [Ca4]F[Ca2Th4]T[(SiO4)6]O2.

    Science.gov (United States)

    Bulanov, Evgeny N; Wang, Jingxian; Knyazev, Alexander V; White, Tim; Manyakina, Marina E; Baikie, Tom; Lapshin, Alexander N; Dong, ZhiLi

    2015-12-01

    Thorium silicate apatite with the formula [Ca3.84Th0.16]F[Ca2.79Th3.21]T(SiO4)6O2 · x(H) was synthesized by solid-state reaction, and its structure refined in P63/m from powder X-ray diffraction (XRD) data using the Rietveld method (a = 9.50172(9) Å, c = 6.98302(8) Å, V = 545.98(1) Å(3); R-Bragg = 2.102%). It was found that thorium partitions strongly to the tunnel (T) 6h position rather than the framework (F) 4f site. Fourier transform infrared spectroscopy revealed only SiO4 tetrahedron, with SiO5 and SiO6 groups, sometimes observed in siliceous apatites absent, at least to the limit of detection of this technique. Thermal expansion of the thorium apatite determined by high-temperature XRD from 298-1173 K found Δa (0.87%) dilation to exceed Δc (0.73%) with increasing temperature consistent with other silicate apatites. PMID:26562353

  3. Disposable competitive-type immunoassay for determination of aflatoxin B1 via detection of copper ions released from Cu-apatite.

    Science.gov (United States)

    Wang, Huan; Zhang, Yihe; Chu, Yanguang; Ma, Hongmin; Li, Yan; Wu, Dan; Du, Bin; Wei, Qin

    2016-01-15

    A disposable electrochemical immunosensor was developed for detection of aflatoxin B1 (AFB1) based on stripping voltammetric detection of copper ions released from Cu-apatite. AFB1 antibody (Ab) was firstly fixed on the gold nanoparticle (Au NPs) modified screen-printed carbon electrode (SPCE). AFB1-bovine serum albumin (AFB1-BSA) conjugate was labeled with Cu-apatite, and then competed with AFB1 for binding to the Ab. Copper ions were released from Cu-apatite through acidolysis and stripping voltammetry signal of the copper ions was used for the detection. The Cu-apatite increased the amount of loaded copper ions, and the anodic stripping strategy performed in the micro electrolytic cell of the SPCE simplified the detection procedure and further amplified the electrochemical signal. This immunosensor could detect AFB1 over a wide concentration range from 0.001 to 100ng mL(-1) with a detection limit of 0.2pg mL(-1). The low cost, high sensitive, rapid and accurate method may find widely potential application in the detection of other toxic or harmful substances.

  4. Bony defect repair in rabbit using hybrid rapid prototyping polylactic co glycolic acid/β tricalciumphosphate collagen I/apatite scaffold and bone marrow mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    Long Pang

    2013-01-01

    Full Text Available Background: In bone tissue engineering, extracellular matrix exerts critical influence on cellular interaction with porous biomaterial and the apatite playing an important role in the bonding process of biomaterial to bone tissue. The aim of this study was to observe the therapeutic effects of hybrid rapid prototyping (RP scaffolds comprising polylactic-co-glycolic acid (PLGA, β-tricalciumphosphate (β-TCP, collagen I and apatite (PLGA/β-TCP-collagen I/apatite on segmental bone defects in conjunction with combination with bone marrow mesenchymal stem cells (BMSCs. Materials and Methods: BMSCs were seeded into the hybrid RP scaffolds to repair 15 mm defect in the radius of rabbits. Radiograph, microcomputed tomography and histology were used to evaluate new bone formation. Results: Radiographic analysis done from 12 to 36 weeks postoperative period demonstrated that new bone formed at the radial defect site and continues to increase until the medullary cavity is recanalized and remodelling is complete. The bone defect remained unconnected in the original RP scaffolds (PLGA/β-TCP during the whole study. Histological observations conformed to the radiographic images. In hybrid RP scaffold group, woven bone united the radial defect at 12 weeks and consecutively remodeled into lamellar bone 24 weeks postoperation and finally matured into cortical bone with normal marrow cavity after another 12 weeks. No bone formation but connective tissue has been detected in RP scaffold at the same time. Conclusion: Collagen I/apatite sponge composite coating could improve new bone formation in vivo. The hybrid RP scaffold of PLGA/β-TCP skeleton with collagen I/apatite sponge composite coating is a promising candidate for bone tissue engineering.

  5. Contribution to the study of sorption mechanisms at solid-liquid interfaces: application to the cases of apatites and oxy-hydroxides

    International Nuclear Information System (INIS)

    Sorption-desorption phenomena play an important role in the transport of toxic and radioactive elements in surface and underground water in contact with solid matter. Selenium, which is one of the long-lived radionuclides present in radioactive waste, is characterized by several oxidation states and by anionic species in aqueous solutions. In order to predict its transport, we need a good knowledge of its sorption processes. We have studied the sorption of Se(IV) and Se(VI) on two types of solids present in natural media or which have been proposed as additives to active barriers: hydroxy-apatites, fluoro-apatite and iron oxi-hydroxides (goethite and hematite). Sorption mechanisms have been studied through an approach including several different and complementary methods: titrimetry, zeta-metry, scanning and transmission electron microscopy, infrared spectroscopy, X-ray diffraction, X-ray photo electron spectroscopy, etc... Results showed that Se(VI) is much less sorbed than Se(VI) on both types of solids. For Se(IV) the sorption mechanisms are different for iron oxides and apatites. On oxides, sorption increases when pH decreases. It can be interpreted by a surface complexation model, essentially through an inner sphere complex (monodentate or bidentate). Modelling of Se sorption curves was performed after the determination of acido-basic properties of oxides. However, the determination of the intrinsic properties of oxides is disturbed by several parameters identified as impurities, evolution of the solid in solution, kinetic and solubility of the solid. For apatites, selenium sorption proceeds by exchange with superficial groups, with a maximum of fixation at approximately pH 8. Thanks to XPS measurements and the elaboration of a mathematical model, we could determine the depth of penetration of both selenium and cadmium on apatites. (author)

  6. Immobilization of RGD Peptide onto the Surface of Apatite-Wollastonite Ceramic for Enhanced Osteoblast Adhesion and Bone Regeneration

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiang; GU Jianwen; ZHANG Yue; TAN Yanfei; ZHOU Jiabei; ZHOU Dali

    2014-01-01

    The arginine-glycine-aspartic (RGD) acid peptide was grafted to the surface of apatite-wollastonite (AW) ceramic in an effort to improve its cell adhesion, proliferation and osteoinduction. RGD peptide was covalently immobilized onto the surface of AW ceramic via the synthetic cross linker AAPTS-E and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The modified surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The chemical analysis indicated that RGD peptide had been immobilized onto the AW surface successfully. The growth of osteoblast-like cells (MG63) showed that modifying the AW surface with RGD peptide enhanced the cell adhesion and proliferation. And the histological evaluation of RGD-AW showed that the bone regeneration and remodeling process were significantly enhanced compared to the original AW ceramics after 2, 4 and 8 weeks implantation in rabbit’s femoral condyles.

  7. Thermal modeling and geomorphology of the south border of the Sao Francisco Craton: thermochronology by fission tracks in apatites

    International Nuclear Information System (INIS)

    Recent developments in Fission Track thermochronology associated to mesozoic-cenozoic erosion and tectonic presented trough thematic maps (isotemperature), permit to model the landscape evolution in the southern border of the Sao Francisco craton, southeastern Brazil. Paleotemperature, obtained by fission track analysis in apatite, is closely related to geomorphologic interpretations. The area suffered a complex imprint of endogenous and exogenous processes resulting diversified and differentiated relieves. The landscape is strongly controlled by exhumation between Jurassic and Lower Cretaceous, uplift with tectonic denudation related to crustal heating at the Upper Cretaceous and reactivation of faults until the Miocene. This scenario is a result of reactivations of different brittle structures that accommodate the deformation in the southern border of the Sao Francisco craton. The landscape reflects denudations of up to 3 km with preserved remains of erosive surfaces in the topographical tops and chronocorrelates deposits in the basins of the region. (author)

  8. Apatite formation on alkaline-treated dense TiO2 coatings deposited using the solution precursor plasma spray process.

    Science.gov (United States)

    Chen, Dianying; Jordan, Eric H; Gell, Maurice; Wei, Mei

    2008-05-01

    A dense titania (TiO2) coating was deposited from an ethanol-based solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. SEM micrographs show the as-sprayed coating is dense with a uniform thickness and there are no coarse splat boundaries. The as-sprayed coating was chemically treated in 5M NaOH solution at 80 degrees C for 48 h. The bioactivity of as-sprayed and alkaline-treated coatings was investigated by immersing the coatings in simulated body fluid (SBF) for 14-28 days, respectively. After 28 days immersion, there is a complete layer of carbonate-containing apatite formed on the alkaline-treated TiO2 coating surface, but none formed on the as-sprayed coating.

  9. Partitioning in REE-saturating minerals - Theory, experiment, and modelling of whitlockite, apatite, and evolution of lunar residual magmas

    Science.gov (United States)

    Jolliff, Bradley L.; Haskin, Larry A.; Colson, Russell O.; Wadhwa, Meenakshi

    1993-01-01

    Compositions, including REEs determined by ion microprobe, of apatite and whitlockite in lunar rock assemblages rich in incompatible trace elements, are presented. Concentrations of REEs in lunar whitlockites are high, ranging from about 1.2 to 2.1 REEs (lanthanides + Y) per 56 oxygens. This slightly exceeds the level of two REE atoms per 56 oxygens at which the dominant substitution theoretically becomes saturated. This saturation effect leads to whitlockite REE(3+) D values at typical lunar whitlockite REE concentrations which are 30-40 percent lower than the D values at low concentrations. The halogen-to-phosphorous ratio in lunar melts is a key factor determining the REE distribution with crystalline assemblages. As long as P and REE concentrations of melts are in KREEP-like proportions, one or both of the phosphates will saturate in melts at similar REE concentrations.

  10. Apatite fission track dating by LA-ICP-MS and External Detector Method: How do they stack up?

    Science.gov (United States)

    Seiler, C.; Gleadow, A. J.; Kohn, B. P.

    2013-12-01

    Analysis of trace element compositions by laser ablation ICP-MS has become a widely used tool to determine in-situ ages in geochronology. Although used primarily for U-Pb dating, LA-ICP-MS has been successfully adapted to other dating techniques such as apatite fission track (Hasebe et al., 2004) or (U-Th)/He (Boyce et al., 2006), making it an ideal tool for multi-system thermochronological studies. LA-ICP-MS fission track dating has several important advantages over the traditional external detector method (EDM), particularly in terms of sample turn-around time and the fact that neutron irradiations (and the handling of radioactive materials) are no longer necessary, while providing a similar level of in-situ information. Perhaps the most important benefits of LA-ICP-MS fission track dating is that it could potentially be used as an absolute dating technique with no Zeta-calibration necessary. However, beyond the initial study of Hasebe et al. (2004), little work has been done to compare results obtained by LA-ICP-MS with those from EDM analysis, and it remains unclear whether the two methods yield equivalent results. We present an extensive dataset of fission track results that were analysed using both LA-ICP-MS and EDM dating. The samples were selected to represent a variety of compositions, with single grain ages ranging from a few million to over a billion years. Both techniques were applied on identical grains, thereby eliminating uncertainties associated with natural variability. The comparison shows that, with a few exceptions, single grain fission track ages from LA-ICP-MS and EDM are concordant within analytical uncertainties and scatter symmetrically around the 1:1 correlation line. Although the relative difference in single grain ages varies significantly in either direction (up to 70%), there are no systematic variations between the two methods suggesting that this variation is simply due to random sampling effects. However, we did find systematic

  11. Gamma dose response of synthetic A-type carbonated apatite in comparison with the response of tooth enamel

    International Nuclear Information System (INIS)

    Synthetic A-type carbonated apatite samples were irradiated at room temperature with 60Co γ rays. Their ESR spectra consist of the lines of CO2- and CO3- radicals of orthorhombic and axial symmetry. The measurements carried out immediately after sample irradiation showed that CO2- species are produced by decomposition of CO3- radicals. Intensity of the CO2- lines in the synthetic and enamel samples increases during the first 400 and 200 h after irradiation, respectively. The dependence of the EPR signal on the dose varies with carbonate content of the sample. The dose response curve for tooth enamel is steeper for the synthetic material. Nonuniformity in the radical site structure in the synthetic samples may arise in the process of sample preparation; this nonuniformity affects the shape of the dose-response curve

  12. Relation between denudation history and sediment supply from apatite fission track thermochronology in the northeast Brazilian Margin

    Science.gov (United States)

    Jelinek, Andrea; Chemale, Farid; Bueno, Gilmar

    2014-05-01

    The aim of this study is to provide a quantitative overview of Mesozoic-Cenozoic morphotectonic evolution and sediment supply to the northeast Brazilian margin. Landscape evolution and denudation histories for the northeastern Brazilian continental margin (Sergipe, Alagoas, Bahia, and Espírito Santo states) were detailed by apatite fission track thermochronology and thermal-history modeling and related with the sedimentological record of the offshore basins of the passive margin for a comparison with their denudational history. Approximately one hundred basement samples were analyzed from the coast to the inland of the Brazilian margin. The apparent fission track ages vary from 360 to 61 Ma and confined fission track lengths vary between 10 and 14.6 µm, indicating that not all of the samples recorded the same cooling events. The results of apatite fission track ages indicate that the area has been eroded regionally since the Mesozoic (Conquista and Borborema Plateaus, and Mantiqueira Range record a Cretaceous-Paleogene onset of exhumation. This timing is consistent with the offshore sedimentary record, wherein a large clastic wedge started forming in the northeastern Sergipe-Alagoas basin, which suggests Sergipe-Alagoas basin records drainage reorganization and extension of the São Francisco River catchment. Interestingly, the Camamu basin, adjacent to the section of the margin does not record syn/post-rift exhumation, does contain a 6-km thick sedimentary succession, which should thus have been derived from more distal sources. The Neogene final denudation is observed throughout the study area and show conspicuous recent exhumation. The post-rift (<40 Ma) offshore sedimentation rates are generally lower than during preceding phases. This final sedimentary succession is thinner in all basins, consistent with limited onshore erosion during this time.

  13. The Orientation of Nanoscale Apatite Platelets in Relation to Osteoblastic-Osteocyte Lacunae on Trabecular Bone Surface.

    Science.gov (United States)

    Shah, Furqan A; Zanghellini, Ezio; Matic, Aleksandar; Thomsen, Peter; Palmquist, Anders

    2016-02-01

    The orientation of nanoscale mineral platelets was quantitatively evaluated in relation to the shape of lacunae associated with partially embedded osteocytes (osteoblastic-osteocytes) on the surface of deproteinised trabecular bone of adult sheep. By scanning electron microscopy and image analysis, the mean orientation of mineral platelets at the osteoblastic-osteocyte lacuna (Ot.Lc) floor was found to be 19° ± 14° in the tibia and 20° ± 14° in the femur. Further, the mineral platelets showed a high degree of directional coherency: 37 ± 7% in the tibia and 38 ± 9% in the femur. The majority of Ot.Lc in the tibia (69.37%) and the femur (74.77%) exhibited a mean orientation of mineral platelets between 0° and 25°, with the largest fraction within a 15°-20° range, 17.12 and 19.8% in the tibia and femur, respectively. Energy dispersive X-ray spectroscopy and Raman spectroscopy were used to characterise the features observed on the anorganic bone surface. The Ca/P (atomic %) ratio was 1.69 ± 0.1 within the Ot.Lc and 1.68 ± 0.1 externally. Raman spectra of NaOCl-treated bone showed peaks associated with carbonated apatite: ν1, ν2 and ν4 PO4(3-), and ν1 CO3(2-), while the collagen amide bands were greatly reduced in intensity compared to untreated bone. The apatite-to-collagen ratio increased considerably after deproteinisation; however, the mineral crystallinity and the carbonate-to-phosphate ratios were unaffected. The ~19°-20° orientation of mineral platelets in at the Ot.Lc floor may be attributable to a gradual rotation of osteoblasts in successive layers relative to the underlying surface, giving rise to the twisted plywood-like pattern of lamellar bone. PMID:26472430

  14. Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability

    Directory of Open Access Journals (Sweden)

    Suzan Bsat

    2015-04-01

    Full Text Available Advanced additive manufacturing techniques such as electron beam melting (EBM, can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M and immersion times (6, 24 h of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200–300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.

  15. Phanerozoic polycyclic evolution of the southwestern Angola margin: New insights for apatite fission track and (U-Th)/He methodologies

    Science.gov (United States)

    Venancio da Silva, Bruno; Hackspacher, Peter; Carina Siqueira Ribeiro, Marli; Glasmacher, Ulrich Anton

    2016-04-01

    The low-temperature thermochronology has been an important tool to quantify geological process in passive continental margins. In this context, the Angolan margin shows evidence of a polycyclic post-rift evolution marked by different events of uplift, basin inversion and changes in sedimentation rates to the marginal basins, which have controlled the salt tectonics and the hydrocarbon deposits (1,2,3,4). To understand the post break-up evolution of the southwestern Angola margin, it were collected outcrop samples for apatite fission track (AFT) and (U-Th)/He analysis ranging in elevation from 79 m to 1675 m from the coast toward the interior plateau in a profile between Namibe and Lubango cities. The area lies on the edge of Central and Southern Atlantic segments a few kilometers northward the Walvis ridge and encompasses the Archean and Proterozoic basement rocks of the Congo craton. The AFT ages ranging from 120.6 ± 8.9 Ma to 328.8 ± 28.5 Ma and they show a trend of increasing age toward the Great Escarpment with some exceptions. The partial mean track lengths (MTLs) vary between 11.77 ± 1.82 μm to 12.34 ± 1.13 μm with unimodal track length distributions (TDLs). The partial (U-Th)/He ages ranging from 104.85 ± 3.15 Ma to 146.95 ± 4.41 Ma and show the same trend of increasing ages landward, little younger than the AFT ages, which could be interpreted as a fast exhumation episode in Late Jurassic - Early Cretaceous times. The thermal histories modelling has been constrained with the kinetic parameters Dpar (5) and c-axis angle (6) by the software Hefty (7). Both AFT and (U-Th)/He thermal histories modelling indicate three episodes of denudation/uplift driven cooling: (a) from Late Jurassic to Early Cretaceous, (b) a smallest one in the Late Cretaceous and (c) from Oligocene-Miocene to recent, which are compatible with geophysical data of the offshore Namibe basin that estimate the greater thickness of sediments formed in the first and third episodes

  16. Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

    Science.gov (United States)

    Aufort, Julie; Ségalen, Loïc; Gervais, Christel; Brouder, Christian; Balan, Etienne

    2016-06-01

    Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between the ATR crystal and the powder sample was used to analyze the line shape of the spectra. The dielectric properties of the samples were related to those of pure fluorapatite using an effective medium approach, based on Maxwell-Garnett and Bruggeman models. The Bruggeman effective medium model leads to a very good agreement with the experimental data recorded on the synthetic fluorapatite sample. The poorer agreement observed on the natural sample suggests a more significant heterogeneity of the sample at a characteristic length scale larger than the mid-infrared characteristic wavelength, i.e., about 10 micrometers. The results demonstrate the prominent role of macroscopic electrostatic effects over fine details of the microscopic structure in determining the line shape of strong ATR bands.

  17. Biological Macromolecule Crystallization Database

    Science.gov (United States)

    SRD 21 Biological Macromolecule Crystallization Database (Web, free access)   The Biological Macromolecule Crystallization Database and NASA Archive for Protein Crystal Growth Data (BMCD) contains the conditions reported for the crystallization of proteins and nucleic acids used in X-ray structure determinations and archives the results of microgravity macromolecule crystallization studies.

  18. Crystallization process

    Science.gov (United States)

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  19. Ribbon crystals.

    Directory of Open Access Journals (Sweden)

    Jakob Bohr

    Full Text Available A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons using a ruled procedure where ribbons are uniquely described by two generating functions. This construction defines a differentiable frame, the ribbon frame, which does not have singular points, whereby we avoid the shortcomings of the Frenet-Serret frame. The observed spontaneous pattern is modeled using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long-range order.

  20. 仿生法沉积磷灰石层的研究进展%Progress in the Study of Biomimetic Process for Depositing Apatite Coatings

    Institute of Scientific and Technical Information of China (English)

    付涛; 徐可为

    2001-01-01

    仿生法沉积磷灰石层模仿了自然界磷灰石的 沉积过程,为生物材料的研制开辟了新途径。本文对生物模仿沉积磷灰石方法的过程、机制 以及涂层的力学和生物学性能作了介绍。%The biomimetic method, which mimics the natural dep osition of biologic apatite, has opened up a new way to develop biomaterials. Th is paper gives a brief introduction of various biomimetic methods to deposit apatite coatings, and the mechanical and biological properties of the coatings.

  1. 100-NR-2 Apatite Treatability Test: High-Concentration Calcium-Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Vermeul, Vincent R.; Fritz, Brad G.; Fruchter, Jonathan S.; Szecsody, James E.; Williams, Mark D.

    2010-09-01

    Following an evaluation of potential strontium-90 (90Sr) treatment technologies and their applicability under 100-NR-2 hydrogeologic conditions, the U.S. Department of Energy (DOE), Fluor Hanford, Inc. (now CH2M Hill Plateau Remediation Company [CHPRC]), Pacific Northwest National Laboratory, and the Washington State Department of Ecology agreed that the long-term strategy for groundwater remediation at the 100-N Area should include apatite as the primary treatment technology. This agreement was based on results from an evaluation of remedial alternatives that identified the apatite permeable reactive barrier (PRB) technology as the approach showing the greatest promise for reducing 90Sr flux to the Columbia River at a reasonable cost. This letter report documents work completed to date on development of a high-concentration amendment formulation and initial field-scale testing of this amendment solution.

  2. Geochemistry of sapphirine-apatite-calcite-bearing gabbroic dykes from the Finero Phlogopite Peridotite (Ivrea-Verbano Zone): evidence for multistage interaction with the ambient peridotite

    Science.gov (United States)

    Tommaso, Giovanardi; Alberto, Zanetti; Maurizio, Mazzucchelli; Tomoaki, Morishita; Antonio, Langone

    2016-04-01

    The Finero Phlogopite-Peridotite (FPP) is a mantle unit outcropping in the northernmost tip of the Ivrea-Verbano Zone (IVZ, Southern Alps). It shows a virtually complete recrystallization due to pervasive to channelled melt migration. The pervasive metasomatism formed a main lithologic association constituted by phlogopite harzburgites associated to phlogopite pyroxenites (mainly olivine-websterites, websterites and orthopyroxenites). These lithologies are also rich in amphibole and do not show significant chemical gradients among them (Zanetti et al., 1999). The channelled migration stages formed dunite bodies, which sometimes contain stratiform chromitites and, more rarely, pyroxenite layers similar to those associated to phlogopite harzburgite. The FPP also shows a discrete number of other, subordinate rock-types, which are characterised by the presence of apatite usually associated to carbonates (i.e. calcite or dolomite) and exhibit marked modal and chemical gradients with respect to the host phlogopite harzburgite. Examples of these lithologies are apatite-dolomite-bearing wehrlites and harzburgites (e.g. Zanetti et al. 1999; Morishita et al., 2008), apatite-calcite zircon-syenites and hornblendites. Ar-Ar amphibole analysis and U-Pb zircon and apatite data return Triassic ages for these rocks, which have been considered to document the time of melt/fluid injection. Notwithstanding the apparent mineralogical and chemical differences with the main lithologic sequences, apatite-carbonates-bearing rocks have been frequently interpreted as cogenetic to phlogopite harzburgites. To debate the petrogenesis of these rocks, a detailed field, petrological and geochemical investigation has been carried out on a swarm of apatite-calcite-bearing gabbroic veins that randomly cut the main lithologic association. Preliminary investigation evidenced as these veins show complex metasomatic haloes and a symmetric internal layering, characterised by crystallisation of magmatic

  3. New constraints on the origin of the Sierra Madre de Chiapas (south Mexico) from sediment provenance and apatite thermochronometry

    Science.gov (United States)

    Witt, C.; Brichau, S.; Carter, A.

    2012-12-01

    The timing and source of deformation responsible for formation of the Sierra Madre de Chiapas (south Mexico) are unclear. To address this, apatite fission track and U-Th-He thermochronometry, combined with zircon U-Pb dating, were performed on bedrock and sedimentary samples of the Sierra Madre de Chiapas to discern timing of exhumation and identify sediment source areas. The U-Pb results show that Paleocene-Eocene terrigenous units outcropping at the northern section of the Sierra were mostly derived from Grenville (˜1 Ga) basement whereas the internal sections of the chain yield mainly Permian to Triassic ages (circa 270-230 Ma) typical of the Chiapas massif complex. Grenville-sourced sediments are most probably sourced by the Oaxacan block or the Guichicovi complex and were deposited to the north of the Sierra in a foreland setting related to a Laramide deformation front. Other possibly source areas may be related to metasedimentary units widely documented at the south Maya block such as the Baldi unit. The apatite fission track and U-Th-He data combined with previously published results record three main stages in exhumation history: (1) slow exhumation between 35 and 25 Ma affecting mainly the Chiapas massif complex; (2) fast exhumation between 16 and 9 Ma related to the onset of major strike-slip deformation affecting both the Chiapas massif complex and Chiapas fold-and-thrust belt; and (3) a 6 to 5 Ma period of rapid cooling that affected the Chiapas fold-and-thrust belt, coincident with the landward migration of the Caribbean-North America plate boundaries. These data suggest that most of the topographic growth of the Sierra Madre de Chiapas took place in the middle to late Miocene. The new thermochronological evidence combined with stratigraphic and kinematic information suggests that the left-lateral strike-slip faults bounding the Chiapas fold-and-thrust belt to the west may have accommodated most of the displacement between the North American and

  4. Mesozoic exhumation in the coastal region of NW Iberia: Preliminary constraints from apatite fission-track cooling ages

    Science.gov (United States)

    Alvarez-Marrón, Joaquina; Barbero, Luis; Menéndez-Duarte, Rosana; Fernández, Susana

    2013-04-01

    Apatite fission-track (AFT) ages from the Iberian Massif, along the northern coastal region in Galicia are presented. The study aims at unravelling the exhumation history of this higher topography coastal region, the so-called Rías Altas region, next to the northern Iberian margin. The rough topography region is bound to the south by the WNW-ESE trending As Pontes dextral strike-slip fault zone. This fault was active since ca. 30 Ma (Rupelian) up to ca. 21 Ma (Aquitanian). The area comprises mainly Late Proterozoic to Paleozoic metamorphic and igneous rocks from the hinterland of the Variscan orogen. A N-S AFT ages profile from the coast to the southern block of the As Pontes fault reveal progressively younger ages toward the south with the oldest ages (242 ± 12 Ma) located near the coast and the youngest age being 124 ± 7 Ma. The AFT ages at both sides of the As Pontes fault in samples taken at the same elevation are similar within error (124 ± 7and 127 ± 7 Ma) indicating that this strike-slip fault did not cause significant differential exhumation during Oligocene-Early Miocene times. Another important feature shown by these data is that the age-elevation relationship (AER) is negative, the youngest ages being located at the highest elevation (ca. 1000 m. a. s. l). This agrees with recent published data from the easternmost part of the present study area and is an indication of Post-Early Cretaceous long residence time within the upper 2 or 3 km of the crust at temperatures lower than those of the apatite partial annealing zone (60 to 120°C). We interpret the registered exhumation history as mostly related to rifting processes in Pre-Early Cretaceous times. Possibly recording surface processes associated to the two stage rifting episodes in the Triassic and in the Late Jurassic-Early Cretaceous that culminated with formation of the north Iberian Margin. The negative AER suggests that since Early Cretaceous times the whole area underwent topographic changes

  5. Enamel crystals of mice susceptible or resistant to dental fluorosis: an AFM study

    Directory of Open Access Journals (Sweden)

    Marília Afonso Rabelo BUZALAF

    2014-06-01

    Full Text Available Objective: This study aimed to assess the overall apatite crystals profile in the enamel matrix of mice susceptible (A/J strain or resistant (129P3/J strain to dental fluorosis through analyses by atomic force microscopy (AFM. Material and Methods: Samples from the enamel matrix in the early stages of secretion and maturation were obtained from the incisors of mice from both strains. All detectable traces of matrix protein were removed from the samples by a sequential extraction procedure. The purified crystals (n=13 per strain were analyzed qualitatively in the AFM. Surface roughness profile (Ra was measured. Results: The mean (±SD Ra of the crystals of A/J strain (0.58±0.15 nm was lower than the one found for the 129P3/J strain (0.66±0.21 nm but the difference did not reach statistical significance (t=1.187, p=0.247. Crystals of the 129P3/J strain (70.42±6.79 nm were found to be significantly narrower (t=4.013, p=0.0013 than the same parameter measured for the A/J strain (90.42±15.86 nm. Conclusion: enamel crystals of the 129P3/J strain are narrower, which is indicative of slower crystal growth and could interfere in the occurrence of dental fluorosis.

  6. Apatite fission track analysis for revealing tectonic events of the Bayinguole area in the west section of Eastern Kunlun Mountains, northern Qinghai-Tibet Plateau

    International Nuclear Information System (INIS)

    Background: Qimantage is an important tectonic metallogenic belt in western part of East Kunlun Mountain. It has experienced complex geological evolution, and significant mineralization. However, because of the plateau climate and inaccessibility, fewer research works have been done on this area, especially after Indo-sinian epoch. Purpose: Our work is to research tectonic activity, thermal history and uplifting around Bayinguole river in Qimantage belt. Methods: The apatite fission-track method was applied to research the tectonic setting, simulate the thermal history and calculate the uplift size and uplift speed. Results: A series of apatite fission track ages from granitoid samples in Bayinguole area of Eastern Kunlun Mountain were obtained, ranging from 120 Ma to 47 Ma that might be divided into three groups': 120-100 Ma, 67 Ma and 54-47 Ma. These ages reflected tectonic events in this area very well. Conclusions: The 120-100 Ma and 67 Ma ages present collision-convergences of Gangdese terrane and Himalayan terrane with their north-side terranes in Early Cretaceous and Late Cretaceous respectively. The ages of 54-47 Ma reflect post-orogenic stretching events in Eocene. Three stages of thermal evolution history are revealed by apatite fission track modeling in this area. Stage one 180-140 Ma is in the bottom temperature of apatite fission track anneal zone. Stage two 140-13 Ma records slow cooling. The last stage after 13 Ma records rapid cooling with temperature dropped 50℃. The uplifting ranges for these three stages are 1.0 km, 0.6 km and 1.4 km, respectively. The cumulative amount of uplift is about 3.0 km. The formula calculations for the 3 samples have their rock uplifts of 3623 m, 3317 m and 3769 m, respectively, averaging 3570 m, in accordance with the results based on the 3 stage thermal history. (authors)

  7. Radiation-induced amorphization of Ce-doped Mg2Y8(SiO4)6O2 silicate apatite

    Science.gov (United States)

    Zhou, Jianren; Yao, Tiankai; Lian, Jie; Shen, Yiqiang; Dong, Zhili; Lu, Fengyuan

    2016-07-01

    Ce-doped Mg2Y8(SiO4)6O2 silicate apatite (Ce = 0.05 and 0.5) were irradiated with 1 MeV Kr2+ ion beam irradiation at different temperatures and their radiation response and the cation composition dependence of the radiation-induced amorphization were studied by in situ TEM. The two Ce-doped Mg2Y8(SiO4)6O2 silicate apatites are sensitive to ion beam induced amorphization with a low critical dose (0.096 dpa) at room temperature, and exhibits significantly different radiation tolerance at elevated temperatures. Ce concentration at the apatite AI site plays a critical role in determining the radiation response of this silicate apatite, in which the Ce3+ rich Mg2Y7.5Ce0.5(SiO4)6O2 displays lower amorphization susceptibility than Mg2Y7.95Ce0.05(SiO4)6O2 with a lower Ce3+ occupancy at the AI sites. The critical temperature (Tc) and activation energy (Ea) change from 667.5 ± 33 K and 0.162 eV of Mg2Y7.5Ce0.5(SiO4)6O2 to 963.6 ± 64 K and 0.206 eV of Mg2Y7.95Ce0.05(SiO4)6O2. We demonstrate that the radiation tolerance can be controlled by varying the chemical composition, and enhanced radiation tolerance is achieved by increasing the Ce concentration at the AI site.

  8. Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

    Directory of Open Access Journals (Sweden)

    Hidetatsu Tanaka

    Full Text Available Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion.

  9. Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

    Science.gov (United States)

    Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

    2016-01-01

    Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

  10. Adsorption of DNA on biomimetic apatites: Toward the understanding of the role of bone and tooth mineral on the preservation of ancient DNA

    OpenAIRE

    Grunenwald, Anne; Keyser, Christine; Sautereau, Anne-Marie; Crubézy, Eric; Ludes, Bertrand; Drouet, Christophe

    2014-01-01

    International audience In order to shed some light on DNA preservation over time in skeletal remains from a physicochemicalviewpoint, adsorption and desorption of DNA on a well characterized synthetic apatite mimicking boneand dentin biominerals were studied. Batch adsorption experiments have been carried out to determinethe effect of contact time (kinetics), DNA concentration (isotherms) and environmentally relevant factorssuch as temperature, ionic strength and pH on the adsorption behav...

  11. In Vitro Screening of the Apatite-Forming Ability, Biointeractivity and Physical Properties of a Tricalcium Silicate Material for Endodontics and Restorative Dentistry

    OpenAIRE

    Maria Giovanna Gandolfi; Francesco Siboni; Antonella Polimeni; Maurizio Bossù; Francesco Riccitiello; Sandro Rengo; Carlo Prati

    2013-01-01

    Aim: Calcium silicate-based materials are hydraulic self-setting materials with physico-chemical properties suitable for endodontic surgery and good biological/clinical outcomes. The study aim was to evaluate the bio-properties (biointeractivity and apatite-forming ability) and selected physical properties (porosity, water sorption, solubility, and setting time) of Biodentine, a tricalcium silicate material for endodontics and restorative dentistry, compared to that of ProRoot MTA (Mineral ...

  12. Hanford 100N Area Apatite Emplacement: Laboratory Results of Ca-Citrate-PO4 Solution Injection and Sr-90 Immobilization in 100N Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E.; Burns, Carolyn A.; Moore, Robert C.; Fruchter, Jonathan S.; Vermeul, Vincent R.; Williams, Mark D.; Girvin, Donald C.; McKinley, James P.; Truex, Michael J.; Phillips, Jerry L.

    2007-10-01

    This report summarizes laboratory scale studies investigating the remediation of Sr-90 by Ca-citrate-PO4 solution injection/infiltration to support field injection activities in the Hanford 100N area. This study is focused on experimentally testing whether this remediation technology can be effective under field scale conditions to mitigate Sr-90 migration 100N area sediments into the Columbia River. Sr-90 is found primarily adsorbed to sediments by ion exchange (99% adsorbed, < 1% in groundwater) in the upper portion of the unconfined aquifer and lower vadose zone. Although primarily adsorbed, Sr-90 is still considered a high mobility risk as it is mobilized by seasonal river stage increases and by plumes of higher ionic strength relative to groundwater. This remediation technology relies upon the Ca-citrate-PO4 solution forming apatite precipitate [Ca6(PO4)10(OH)2], which incorporates some Sr-90 during initial precipitation and additionally slowly incorporates Sr-90 by solid phase substitution for Ca. Sr substitution occurs because Sr-apatite is thermodynamically more stable than Ca-apatite. Once the Sr-90 is in the apatite structure, Sr-90 will decay to Y-90 (29.1 y half-life) then Zr-90 (64.1 h half-life) without the potential for migration into the Columbia River. For this technology to be effective, sufficient apatite needs to be emplaced in sediments to incorporate Sr and Sr-90 for 300 years (~10 half-lives of Sr-90), and the rate of incorporation needs to exceed the natural groundwater flux rate of Sr in the 100N area. A primary objective of this study is to supply an injection sequence to deliver sufficient apatite into subsurface sediments that minimizes initial mobility of Sr-90, which occurs because the injection solution has a higher ionic strength compared to groundwater. This can be accomplished by sequential injections of low, then high concentration injection of Ca-citrate-PO4 solutions. Assessment of low concentration Ca-citrate-PO4, citrate-PO4

  13. Zircon and apatite fission track analyses on mineralization ages and tectonic activities of Tuwu-Yandong porphyry copper deposit in northern Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The mineralization ages reported in the past in the Tuwu-Yandong copper district not only are different, but also fall into the Hercynian epoch. This study has achieved 9 zircon and 7 apatite fission track analysis results. The zircon fission track ages range from 158 Ma to 289 Ma and the apatite ages are between 64 Ma and 140 Ma. The mineralization accords with the regional tectonics in the copper district. We consider that the zircon fission track age could reveal the mineralization age based on annealing zone temperature of 140-300℃ and retention temperature of ~250℃ for zircon fission track, and metallogenetic temperature of 120-350℃ in this ore district. Total three mineralization epochs have been identified, i.e., 289-276 Ma,232-200 Ma and 165-158 Ma, and indicate occurrence of the mineralization in the Indosinian and Yanshan epochs. Corresponding to apatite fission track ages, the three tectonic-mineralizing epochs are 140-132 Ma, 109-97 Ma and 64 Ma, which means age at about 100℃ after the mineralization. The three epochs lasted 146 Ma, 108 Ma and about 100 Ma from ~250℃ to ~100℃ and trend decrease from early to late. It is shown by the fission track modeling that this district underwent three stages of geological thermal histories, stable in Cretaceous and cooling both before Cretaceous and after 20 Ma.

  14. Evidence for the Multi-Stage Petrogenetic History of the Oka Carbonatite Complex (Québec, Canada as Recorded by Perovskite and Apatite

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2014-05-01

    Full Text Available The Oka complex is amongst the youngest carbonatite occurrences in North America and is associated with the Monteregian Igneous Province (MIP; Québec, Canada. The complex consists of both carbonatite and undersaturated silicate rocks (e.g., ijolite, alnöite, and their relative emplacement history is uncertain. The aim of this study is to decipher the petrogenetic history of Oka via the compositional, isotopic and geochronological investigation of accessory minerals, perovskite and apatite, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS. The new compositional data for individual perovskite and apatite grains from both carbonatite and associated alkaline silicate rocks are highly variable and indicative of open system behavior. In situ Sr and Nd isotopic compositions for these two minerals are also variable and support the involvement of several mantle sources. U-Pb ages for both perovskite and apatite define a bimodal distribution, and range between 113 and 135 Ma, which overlaps the range of ages reported previously for Oka and the entire MIP. The overall distribution of ages indicates that alnöite was intruded first, followed by okaite and carbonatite, whereas ijolite defines a bimodal emplacement history. The combined chemical, isotopic, and geochronological data is best explained by invoking the periodic generation of small volume, partial melts generated from heterogeneous mantle.

  15. Petrography and the REE-composition of apatite in the Paleoproterozoic Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia

    Science.gov (United States)

    Joosu, Lauri; Lepland, Aivo; Kreitsmann, Timmu; Üpraus, Kärt; Roberts, Nick M. W.; Paiste, Päärn; Martin, Adam P.; Kirsimäe, Kalle

    2016-08-01

    The first globally significant phosphorous-rich deposits appear in the Paleoproterozoic at around 2 Ga, however, the specific triggers leading to apatite precipitation are debated. We examine phosphorous-rich rocks (up to 8 wt% P2O5) in 1.98-1.92 Ga old Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia. Phosphates in these rocks occur as locally derived and resedimented sand-to-gravel/pebble sized grains consisting of apatite-cemented muddy sediments. Phosphatic grains can be subdivided into four petrographic types (A-D), each has a distinct REE signature reflecting different early-to-late diagenetic conditions and/or metamorphic overprint. Pyrite containing petrographic type D, which typically has a flat REE pattern, negative Ce anomaly and positive Eu anomaly, is the best preserved of the four types and best records conditions present during apatite precipitation. Type D phosphatic grains precipitated under (sub)oxic basinal conditions with a significant hydrothermal influence. These characteristics are similar to Zaonega Formation phosphates of NW Russia's Onega Basin, and consistent with phosphogenesis triggered by the development of anoxic(sulfidic)-(sub)oxic redoxclines at shallow sediment depth during the Paleoproterozoic.

  16. Roundness of heavy minerals (zircon and apatite) as a provenance tool for unraveling recycling: A case study from the Sefidrud and Sarbaz rivers in N and SE Iran

    Science.gov (United States)

    Zoleikhaei, Yousef; Frei, Dirk; Morton, Andrew; Zamanzadeh, S. Mohammad

    2016-08-01

    In order to improve techniques for provenance studies, and especially to address the question of sediment recycling, morphological changes of two minerals with contrasting durability (zircon and apatite) were tracked during both fluvial transport and littoral reworking. The Sefidrud river system in northern Iran, which drains the Alborz volcano-sedimentary range into the Caspian Sea, and the Sarbaz river system in southeastern Iran, which drains the Makran Accretionary Prism into the Oman Sea, were chosen for this study. To determine source rocks of the grains, and thus their nature in terms of sedimentary cycles, zircon geochronology was conducted on both rivers. The zircon data indicate that most of the Sefidrud sediments are first cycle, derived from crystalline rocks, and the Sarbaz sediments are generally recycled from older wedges of the Makran. Results from SEM analysis show significant differences between the roundness of associated zircon and apatite grains. Zircon grains remain unrounded through several cycles, while apatite grains show abrasion from the early stages of their first cycle.

  17. Contribution to the study of sorption mechanisms at solid-liquid interfaces: application to the cases of apatites and oxy-hydroxides; Contribution a l'etude des mecanismes de sorption aux interfaces solide-liquide: application aux cas des apatites et des oxy-hydroxydes

    Energy Technology Data Exchange (ETDEWEB)

    Duc, M

    2002-11-15

    Sorption-desorption phenomena play an important role in the transport of toxic and radioactive elements in surface and underground water in contact with solid matter. Selenium, which is one of the long-lived radionuclides present in radioactive waste, is characterized by several oxidation states and by anionic species in aqueous solutions. In order to predict its transport, we need a good knowledge of its sorption processes. We have studied the sorption of Se(IV) and Se(VI) on two types of solids present in natural media or which have been proposed as additives to active barriers: hydroxy-apatites, fluoro-apatite and iron oxi-hydroxides (goethite and hematite). Sorption mechanisms have been studied through an approach including several different and complementary methods: titrimetry, zeta-metry, scanning and transmission electron microscopy, infrared spectroscopy, X-ray diffraction, X-ray photo electron spectroscopy, etc... Results showed that Se(VI) is much less sorbed than Se(VI) on both types of solids. For Se(IV) the sorption mechanisms are different for iron oxides and apatites. On oxides, sorption increases when pH decreases. It can be interpreted by a surface complexation model, essentially through an inner sphere complex (monodentate or bidentate). Modelling of Se sorption curves was performed after the determination of acido-basic properties of oxides. However, the determination of the intrinsic properties of oxides is disturbed by several parameters identified as impurities, evolution of the solid in solution, kinetic and solubility of the solid. For apatites, selenium sorption proceeds by exchange with superficial groups, with a maximum of fixation at approximately pH 8. Thanks to XPS measurements and the elaboration of a mathematical model, we could determine the depth of penetration of both selenium and cadmium on apatites. (author)

  18. MECHANISMS CONTROLLING Ca ION RELEASE FROM SOL-GEL DERIVED IN SITU APATITE-SILICA NANOCOMPOSITE POWDER

    Directory of Open Access Journals (Sweden)

    Seyed Mohsen Latifi

    2015-03-01

    Full Text Available Ca ion release from bioactive biomaterials could play an important role in their bioactivity and osteoconductivity properties. In order to improve hydroxyapatite (HA dissolution rate, in situ apatite-silica nanocomposite powders with various silica contents were synthesized via sol-gel method and mechanisms controlling the Ca ion release from them were investigated. Obtained powders were characterized by X-ray diffraction (XRD and transmission electron spectroscopy (TEM techniques, acid dissolution test, and spectroscopy by atomic absorption spectrometer (AAS. Results indicated the possible incorporation of (SiO44- into the HA structure and tendency of amorphous silica to cover the surface of HA particles. However, 20 wt. % silica was the lowest amount that fully covered HA particles. All of the nanocomposite powders showed more Ca ion release compared with pure HA, and HA - 10 wt. % silica had the highest Ca ion release. The crystallinity, the crystallite size, and the content of HA, along with the integrity, thickness, and ion diffusion possibility through the amorphous silica layer on the surface of HA, were factors that varied due to changes in the silica content and were affected the Ca ion release from nanocomposite powders.

  19. Late Mesozoic Thermotectonic Evolution of the Jueluotage Range,Eastern Xinjiang, Northwest China: Evidence from Apatite Fission Track Data

    Institute of Scientific and Technical Information of China (English)

    ZHU Wenbin; WAN Jinglin; SHU Liangshu; ZHANG Zhiyong; SU Jinbao; SUN Yan; GUO Jichun; ZHANG Xueyun

    2008-01-01

    Although many authors have emphasized the Cenozoic history of deformation, exhumation and cooling in the Tiaushan area related to the India-Asia collision, very little is known about the Mesozoic history of compression and uplift within the Tianshan. In order to obtain information about the Mesozoic exhumation history and processes of cooling in eastern Tianshan, fission track methods on apatite were used. Sampling was made in the Jueluotage Range. Three samples (Z001-Z003) were taken from granite in borehole ZK6301 of Yandong pluton; the ages range from 97.0 to 87.6 Ma that are much younger than the pluton age which was dated by U-Pb zircon at 334±2 Ma. Two samples in northern piedmont of the Jueluotage Range were collected from Jurassic strata in Dikaner (DK001) and Dananhu (D001) whose ages are 91.5 and 93.4 Ma respectively. The average apparent exhumation rate is 0.039 mm/a calculated by extrapolation on the basis of Yandong samples, indicating an extremely slow exhumation in the Jueluotage Range since the Late Cretaceous. Two Jurassic samples reached the maximum depths after deposition and experienced the maximum temperatures of ca. 105 and 108℃ until the late Early Cretaceous before a period of cooling and exhumation occurred at 114 and 106 Ma.

  20. Regenerative potential and anti-bacterial activity of tetracycline loaded apatitic nanocarriers for the treatment of periodontitis

    International Nuclear Information System (INIS)

    Current treatment of periodontal infections includes mechanical debridement, administration of antibiotics and bone grafting. Oral administration of antibiotics results in undesirable side effects, while current modes of local administration are affected by problems concerning allergic response to the polymeric carrier agents. We have developed an osteoconductive drug delivery system composed of apatitic nanocarriers capable of providing sustained delivery of drugs in the periodontium. Calcium deficient hydroxyapatite (CDHA) nanocarriers of different Ca/P ratios were synthesized and characterized using the x-ray diffraction method, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy and the BET gas isotherm method. Loading and release studies performed with tetracycline showed a sustained release of up to 88% in phosphate buffered saline over a period of five days. Antibacterial activity studies showed that the tetracycline loaded CDHA (TC-CDHA) nanocarriers were effective against S. aureus and E. coli bacteria. The biocompatibility of the TC-CDHA nanocarriers was demonstrated using an alamar blue assay and further characterized by cell uptake studies. Interestingly, cell uptake of drug loaded CDHA also increased the cellular proliferation of human periodontal ligament fibroblast cells. Hence, it can be concluded that the CDHA nanocarriers are ideal drug delivery agents and have bone regenerative potential for local periodontal applications. (paper)

  1. Structure, apatite inducing ability, and corrosion behavior of chitosan/halloysite nanotube coatings prepared by electrophoretic deposition on titanium substrate.

    Science.gov (United States)

    Molaei, A; Amadeh, A; Yari, M; Reza Afshar, M

    2016-02-01

    In this study chitosan/halloysite nanotube composite (CS/HNT) coatings were deposited by electrophoretic deposition (EPD) on titanium substrate. Using HNT particles were investigated as new substituents for carbon nanotubes (CNTs) in chitosan matrix coatings. The ability of chitosan as a stabilizing, charging, and blending agent for HNT particles was exploited. Furthermore, the effects of pH, electrophoretic bath, and sonicating duration were studied on the deposition of suspensions containing HNT particles. Microstructure properties of coatings showed uniform distribution of HNT particles in chitosan matrix to form smooth nanocomposite coatings. The zeta potential results revealed that at pH around 3 there is an isoelectric point for HNT and it would have cathodic and anionic states at pH values less and more than 3, respectively. Therefore, CS/HNT composite deposits were produced in the pH range of 2.5 to 3. The apatite inducing ability of chitosan-HNT composite coating assigned that HNT particles were biocompatible because they formed carbonated hydroxyapatite particles on CS/HNT coating in corrected simulated body fluid (C-SBF). Finally, electrochemical corrosion characterizations determined that corrosion resistance in CS/HNT coating has been improved compared to bare titanium substrate. PMID:26652428

  2. Thermal History of Rocks in the Shiwandashan Basin, Southern China: Evidence from Apatite Fission-Track Analysis

    Institute of Scientific and Technical Information of China (English)

    Wang Xinwei; Wang Xinwen; Ma Yongsheng

    2005-01-01

    Based on interpretations of the apatite fission-track analysis data for 10 outcrop samples and forward modeling of confined fission-track length distributions, the thermal history of rocks in the Shiwandashan basin and its adjacent area, southern China, has been qualitatively and semi-quantitatively studied. The results reflect several features of the thermal history. Firstly, all the samples have experienced temperatures higher than 60-70 ℃. Secondly, the time that the basement strata (T1b) on the northwestern side of the Shiwandashan basin were uplifted and exhumed to the unannealed upper crust (with a paleogeotemperature of below 60-70 ℃) is much earlier than the basement rocks (γ15) on the southeastern side of the basin. Thirdly, the thermal history of samples from the basin can be divided into six stages, I.e., the fast burial and heating stage (220-145 Ma), the transient cooling stage (145-135 Ma), the burial and heating stage (135-70 Ma), the rapid cooling stage (70-50 Ma), the relatively stable stage (50-20 Ma) and another rapid cooling stage (20 Ma to present).

  3. Electrochemical studies and growth of apatite on molybdenum doped DLC coatings on titanium alloy β-21S

    Energy Technology Data Exchange (ETDEWEB)

    Anandan, C., E-mail: canandan@nal.res.in; Mohan, L.; Babu, P. Dilli

    2014-03-01

    Highlights: • Titanium alloy β21S was coated with Mo doped DLC. • XRD, XPS and micro Raman show that Mo is present in the form of carbide. • Mo doping facilitates apatite growth on DLC during immersion in Hanks’ solution. • Mo doped DLC sample shows better passivation behavior in Hanks’ solution. - Abstract: Titanium alloy β-21S (Ti–15Mo–3Nb–3Al–0.2Si) was coated with molybdenum doped DLC by Plasma-enhanced chemical vapor deposition and sputtering. XRD, XPS and Raman spectroscopy show that Mo is present in the form of carbide in the coating. XPS of samples immersed in Hanks’ solution shows presence of calcium, phosphorous and oxygen in hydroxide/phosphate form on the substrate and Mo-doped DLC. Potentiodynamic polarization studies show that the corrosion resistance and passivation behavior of Mo-doped DLC is better than that of substrate. Electrochemical impedance spectroscopy (EIS) studies show that Mo-doped DLC samples behave like an ideal capacitor in Hanks’ solution.

  4. A crystal-chemical investigation of phases of relevance to lime-chromite roast reactions

    International Nuclear Information System (INIS)

    The aim of this investigation was to elucidate the crystal chemistry of phases in the CaO-chromium oxide-Si-O2 system, by single crystal x-ray diffractometry. The crystal chemistry of calcium and chromium-containing phases, with chromium valencies higher than trivalent, which occur in the chromite-lime roast process has been investigated. The phases include the monocalcium, tricalcium and pentacalcium ortho-chromates and the fluor and oxy-chromium apatites. The crystal structures of Ca5Cr3O12 and Ca5Cr1.8Si1.2O12, the chromium analogues of silico-carnotite, Ca5P2SiO12, have been determined. An alternative model for the structure of Ca3(CrO4)2 has been investigated in which some of the (CrO4) tetrahedra are positionally disordered. It is proposed that the structure determined may represent an average of two different structure types and the transformation from the one polymorph to the other involves the alternate flipping of the disordered tetrahedra. The disordered model implies an alternative stoichiometry Ca10(CrO4)7 in which 6/7 of the chromium is pentavalent and 1/7 is hexavalent. The phase chemistry of mixtures of lime and chromite has been examined at temperatures above 850 0C in air. Ca5Cr3O12' Ca5(CrO4)F and Ca3(CrO4)2 are produced as relatively pure phases. Optimum chromite: lime addition is in the order 1:1, such that the product phases include Ca5Cr3O12, Ca4Fe+32Al2O10 and MgO. Reaction kinetics are however unfavourable. By replacing 7% CaO with CaF2, the kinetics are improved. The product phases are fluor-chromium apatite Ca5Cr3O10F, Ca4Fe+32Al2O12 and MgO. The apatite, like Ca5Cr3O12, may be preferentially leached with dilute acid

  5. Apatite fission track dating and long-term landscape evolution of the South Atlantic passive continental margin in the region of the Sierras Septentrionales in eastern Argentina

    Science.gov (United States)

    Pfister, S.; Glasmacher, P. A.; Kollenz, S.

    2013-12-01

    To understand the evolution of the passive continental margin in Argentina apatite fission track dating is an appropriate method, which will lead to new conclusions in this area. The Tandilia System, also called Sierras Septentrionales, is located south of the Río de la Plato Craton in eastern Argentina in the state of Buenos Aires. North of the hills Salado basin is orientated whereas the Claromeó basin is located south of the mountain range. In contrary to most basins along the southamerican passive continental margin the Tandilia-System and the neighbouring basins trend perpendicular to the coast line. The topography ranges between 50 and 250m within the study area and is therefore fairly flat. The igneous-metamorphic basement is pre-proterozoic in age build up of mainly granitic-tonalitic gneisses, migmatites, amphibolites, some ultramafic rocks and granitoid plutons and is overlain by a series of Neoproterozoic to early Paleozoic sediments (Cingolani, 2010). The aim of the study is to evaluate the long-term landscape evolution of the passive continental margin in eastern Argentina in terms of thermal history and exhumation. For that purpose samples were taken from the Sierra Septentrionales basement analyzed for the apatite-FT method. The results so far indicate apatite fission track ages between 146.2 (10.1) Ma and 200.4 (12.7) Ma, which shows all samples have been reseted. Still ongoing length measurements will lead to 2D thermo kinematic Hefty (Ketcham, 2005; Ketcham et al., 2009; Ketcham, 2007) models. This will leads to further more insights on the cooling history and tectonic activities in the research area. References: Cingolani C. A. (2010): The Tandilia System of Argentina as a southern extension of the Río de la Plata craton: an overview. Int. J. Earth Sci. (Geol. Rundsch.) (2011) 100:221-242, doi 10.1007/s00531-010-0611-5. Ketcham, R. A. (2005): Forward and inverse modeling of low-temperature thermochronometry data, in Low

  6. Hydrogen Isotopic Composition of Apatite in Northwest Africa 7034: A Record of the "Intermediate" H-Isotopic Reservoir in the Martian Crust?

    Science.gov (United States)

    McCubbin, F. M.; Barnes, J. J.; Santos, A. R.; Boyce, J. W.; Anand, M.; Franchi, I. A.; Agee, C. B.

    2016-01-01

    Northwest Africa (NWA) 7034 and its pairings comprise a regolith breccia with a basaltic bulk composition [1] that yields a better match than any other martian meteorite to visible-infrared reflectance spectra of the martian surface measured from orbit [2]. The composition of the fine-grained matrix within NWA 7034 bears a striking resemblance to the major element composition estimated for the martian crust, with several exceptions. The NWA 7034 matrix is depleted in Fe, Ti, and Cr and enriched in Al, Na, and P [3]. The differences in Al and Fe are the most substantial, but the Fe content of NWA 7034 matrix falls within the range reported for the southern highlands crust [6]. It was previously suggested by [4] that NWA 7034 was sourced from the southern highlands based on the ancient 4.4 Ga ages recorded in NWA 7034/7533 zircons [4, 5]. In addition, the NWA 7034 matrix material is enriched in incompatible trace elements by a factor of 1.2-1.5 [7] relative to estimates of the bulk martian crust. The La/Yb ratio of the bulk martian crust is estimated to be approximately 3 [7], and the La/Yb of the NWA 7034 matrix materials ranges from approximately 3.9 to 4.4 [3, 8], indicating a higher degree of LREE enrichment in the NWA 7034 matrix materials. This elevated La/Yb ratio and enrichment in incompatible lithophile trace elements is consistent with NWA 7034 representing a more geochemically enriched crustal terrain than is represented by the bulk martian crust, which would be expected if NWA 7034 represents the bulk crust from the southern highlands. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the composition of the martian crust, particularly the ancient highlands. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034. Usui et al., [9] recently proposed that a H isotopic reservoir exists within the martian crust that has

  7. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  8. Crystallized nano-sized alpha-tricalcium phosphate from amorphous calcium phosphate: microstructure, cementation and cell response.

    Science.gov (United States)

    Vecbiskena, Linda; Gross, Karlis Agris; Riekstina, Una; Yang, Thomas Chung-Kuang

    2015-04-01

    New insight on the conversion of amorphous calcium phosphate (ACP) to nano-sized alpha tricalcium phosphate (α-TCP) provides a faster pathway to calcium phosphate bone cements. In this work, synthesized ACP powders were treated with either water or ethanol, dried, crystallized between 700 and 800 °C, and then cooled at different cooling rates. Particle size was measured in a scanning electron microscope, but crystallite size calculated by Rietveld analysis. Phase composition and bonding in the crystallized powder was assessed by x-ray diffraction and Fourier-transform infrared spectroscopy. Results showed that 50 nm sized α-TCP formed after crystallization of lyophilized powders. Water treated ACP retained an unstable state that may allow ordering to nanoapatite, and further transition to β-TCP after crystallization and subsequent decomposition. Powders treated with ethanol, favoured the formation of pure α-TCP. Faster cooling limited the growth of β-TCP. Both the initial contact with water and the cooling rate after crystallization dictated β-TCP formation. Nano-sized α-TCP reacted faster with water to an apatite bone cement than conventionally prepared α-TCP. Water treated and freeze-dried powders showed faster apatite cement formation compared to ethanol treated powders. Good biocompatibility was found in pure α-TCP nanoparticles made from ethanol treatment and with a larger crystallite size. This is the first report of pure α-TCP nanoparticles with a reactivity that has not required additional milling to cause cementation. PMID:25886478

  9. CENOZOIC EXHUMATION OF THE ANTIOQUEÑO PLATEAU, NORTHERN ANDES, COLOMBIA, FROM APATITE LOW-TEMPERATURE THERMOCHRONOLOGY

    Science.gov (United States)

    Restrepo-Moreno, S. A.; Foster, D. A.; O'Sullivan, P. B.; Donelick, R.; Stockli, D. F.

    2009-12-01

    The Antioqueño plateau (AP), in the northernmost Cordillera Central, Colombia, is the most extensive and best preserved relict surface in the Northern Andes. Apatite (U-Th)/He (AHe) and fission track (AFT) results from twenty two samples, collected from paleocrustal depths along two vertical profiles in canyons dissecting the AP, constrain Cenozoic erosional exhumation of this segment of the Andean range. The two profiles exhibit excellent reproducibility of AHe and AFT data. Helium ages increase with elevation from ~22-49 Ma. A marked inflection point in the AHe age-elevation plots at 25 Ma defines the bottom of the post-Oligocene He partial retention zone (PRZ). Virtually invariant ages at ~25 Ma record onset of rapid exhumation in the AP. A more subtle slope change in the PRZ at ~43 Ma is interpreted as a minor exhumation pulse. AFT better defines timing and intensity of Eocene exhumation. AFT ages for both profiles vary from ~30-49 Ma and are consistently older than AHe ages. AFT data display invariant ages (±2σ) between 1500-2400 m elevations while confined track length data exhibit uni-modal distributions with a mean track length of ~14.2 μm. Both facts indicate rapid cooling. This is further supported by virtually concordant AFT and AHe ages for both profiles between 1500 to 2200 m implying that rocks were exhumed from temperatures >120°C to below AHe closure temperature 60°C. Assuming a geothermal gradient of ~25°C/km this corresponds to exhumation rates in the order of 0.5 mm/y, comparable in intensity to the Miocene pulse defined by AHe. Integrated thermal modeling show an episode of rapid cooling at ~43-49 Ma. AFT profiles show an apparent inflection point at ~1400 m, which defines the upper boundary of an apatite partial annealing zone (PAZ) exhumed during the 43-49 Ma cooling event. The position of the PAZ and PRZ relative to the present erosional surface point to average erosion rates of ~0.03 mm/yr, which constitute very low denudation rates

  10. Phanerozoic burial and exhumation history of southernmost Norway estimated from apatite fission-track analysis data and geological observations

    Science.gov (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Chalmers, James A.; Rasmussen, Erik S.

    2016-04-01

    We present new apatite fission-track analysis (AFTA) data from 27 basement samples from Norway south of ~60°N. The data define three events of cooling and exhumation that overlap in time with events defined from AFTA in southern Sweden (Japsen et al. 2015). The samples cooled below palaeotemperatures of >100°C in a major episode of Triassic cooling as also reported by previous studies (Rohrman et al. 1995). Our study area is just south of the Hardangervidda where Cambrian sediments and Caledonian nappes are present. We thus infer that these palaeotemperatures reflect heating below a cover that accumulated during the Palaeozoic and Triassic. By Late Triassic, this cover had been removed from the Utsira High, off SW Norway, resulting in deep weathering of a granitic landscape (Fredin et al. 2014). Our samples were therefore at or close to the surface at this time. Palaeotemperatures reached ~80°C prior to a second phase of cooling and exhumation in the Jurassic, following a phase of Late Triassic - Jurassic burial. Upper Jurassic sandstones rest on basement near Bergen, NW of our study area (Fossen et al. 1997), and we infer that the Jurassic event led to complete removal of any remaining Phanerozoic cover in the region adjacent to the evolving rift system prior to Late Jurassic subsidence and burial. The data reveal a third phase of cooling in the early Miocene when samples that are now near sea level cooled below palaeotemperatures of ~60°C. For likely values of the palaeogeothermal gradient, such palaeotemperatures correspond to burial below rock columns that reach well above the present-day landscape where elevations rarely exceed 1 km above sea level. This implies that the present-day landscape was shaped by Neogene erosion. This is in agreement with the suggestion of Lidmar-Bergström et al. (2013) that the near-horizontal Palaeic surfaces of southern Norway are the result of Cenozoic erosion to sea level followed by uplift to their present elevations in a

  11. Environment and ecology of East Asian dinosaurs during the Early Cretaceous inferred from stable oxygen and carbon isotopes in apatite

    Science.gov (United States)

    Amiot, Romain; Wang, Xu; Zhou, Zhonghe; Wang, Xiaolin; Lécuyer, Christophe; Buffetaut, Eric; Fluteau, Frédéric; Ding, Zhongli; Kusuhashi, Nao; Mo, Jinyou; Philippe, Marc; Suteethorn, Varavudh; Wang, Yuanqing; Xu, Xing

    2015-02-01

    During the cold Late Barremian-Early Albian interval, terrestrial environments in East Asia were populated by rich and diverse vertebrate faunas characterized by a strong provincialism. The latitudinal gradient of temperature and the existence of geographic barriers likely accounted for some aspects of this heterogeneous distribution of faunas. Other factors, however, such as local environmental conditions and interactions within vertebrate communities, which could have influenced their distribution, have not yet been fully identified and understood. Therefore, new and published oxygen and carbon isotope compositions of apatite from Chinese and Thai reptiles (dinosaurs, crocodilians and turtles) have been analyzed and interpreted in terms of ecology, local air temperature and precipitation amounts. Differences in carbon and oxygen isotope compositions between various groups of sympatric plant-eating dinosaurs (sauropods, ornithopods and ceratopsians) indicate food resources partitioning among them most likely to avoid competition. Mid-latitude environments, where the Jehol Biota flourished, were submitted to cool temperate climatic conditions with Mean Air Temperature (MAT) of 10 ± 4 °C and Mean Annual Precipitations (MAP) of about 600 mm/yr compatible with the existence of forest environments. By contrast, sub-tropical regions, characterized by MAT of about 20-25 °C were either submitted to high amounts of seasonal precipitations (of about 1200 mm/yr in Thailand) or to significant aridity (MAP of about 400 mm/yr in South China). This difference in precipitation regime between Thailand and South China may be attributed to the occurrence of the Coastal Cordillera extending along the East margin of the South China block. These mountain ranges likely prevented humid air masses from the Pacific to penetrate some parts of South China, thus generating a "rain shadow effect". Mosaic environments characterizing East Asia during the Late Early Cretaceous may have acted

  12. Optimization of a Biomimetic Apatite Nanoparticle Delivery System for Non-viral Gene Transfection---a Simulated Body Fluid Approach

    Science.gov (United States)

    Das, Debobrato

    Current methods for gene delivery utilize nanocarriers such as liposomes and viral vectors that may produce in vivo toxicity, immunogenicity, or mutagenesis. Moreover, these common high-cost systems have a low efficacy of gene-vehicle transport across the cell plasma membrane followed by inadequate release and weak intracellular stability of the genetic sequence. Thus, this study aims to maximize gene transfection while minimizing cytotoxicity by utilizing supersaturated blood-plasma ions derived from simulated body fluids (SBF). With favorable electrostatic interactions to create biocompatible calcium-phosphate nanoparticles (NPs) derived from biomimetic apatite (BA), results suggest that the SBF system, though naturally sensitive to reaction conditions, after optimization can serve as a tunable and versatile platform for the delivery of various types of nucleic acids. From a systematic exploration of the effects of nucleation pH, incubation temperature, and time on transfection efficiency, the study proposes distinct characteristic trends in SBF BA-NP morphology, cellular uptake, cell viability, and gene modulation. Specifically, with aggressive nucleation and growth of BA-NPs in solution (observed via scanning electron microscopy), the ensuing microenvironment imposes a more toxic cellular interaction (indicated by alamarBlue and BCA assays), limiting particle uptake (fluorescence experiments) and subsequent gene knockdown (quantitative loss of function assays). Controlled precipitation of BA-NPs function to increase particle accessibility by surrounding cells, and subsequently enhance uptake and transfection efficiency. By closely examining such trends, an optimal fabrication condition of pH 6.5-37C can be observed where particle growth is more tamed and less chaotic, providing improved, favorable cellular interactions that increase cell uptake and consequently maximize gene transfection, without compromising cellular viability.

  13. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China:Evidence from apatite fission track analysis

    Institute of Scientific and Technical Information of China (English)

    Wenhao Tang; Zhicheng Zhang; Jianfeng Li; Ke Li; Zhiwen Luo; Yan Chen

    2015-01-01

    Apatite fission track (AFT) analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0e13.2 mm) mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassiceearly Cretaceous and the OligoceneeMiocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma), recording the earlier rapid uplift phase during the late JurassiceCretaceous, while the ages in the north pied-mont of the Bogda Mountain (namely the northeast part) are younger (<60 Ma), mainly reflecting the later rapid uplift phase in the OligoceneeMiocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  14. Uplift and denudation history of the eastern Dead Sea rift flank, SW Jordan: Evidence from apatite fission track thermochronometry

    Science.gov (United States)

    Feinstein, S.; Eyal, M.; Kohn, B. P.; Steckler, M. S.; Ibrahim, K. M.; Moh'd, B. K.; Tian, Y.

    2013-09-01

    Dead Sea rift (DSR), developed along the Dead Sea transform plate boundary, is characterized by salient flanks and morphotectonic asymmetry. Apatite fission track thermochronology (AFT) along ~1200 m high vertical profiles in Neoproterozoic basement and overlying Cambrian sandstone in southwestern Jordan is used to reconstruct timing, magnitude, and rate of uplift and denudation of the eastern DSR flank and examine its relationship to rift development and its flank landscape. Time-temperature models based on AFT data suggest three major Phanerozoic heating and cooling episodes, Late Paleozoic, Early Cretaceous, and Oligocene. The latest episode, on which this study focuses, indicates uplift of ~3.8±0.3 km under a moderate paleogeothermal gradient. About 40% of the uplift was tectonically driven with the remainder attributed to isostatic rebound in response to denudation and erosion. Models suggest that uplift commenced in the Oligocene with a considerable part occurring prior to development of the DSR, despite being ~200 km from the Red Sea-Gulf of Suez rift margin. Uplift is probably part of a regional rearrangement along the western Arabian platform margin occurring at the time of Red Sea rift initiation. Transition from primarily sedimentary layer stripping, most likely by scarp retreat, to one of dominantly incision of the underlying crystalline basement occurred in Late Miocene-Pliocene time following enhanced subsidence and development of a low base level in the DSR. Consequently, the magnitude of uplift by isostatic rebound due to incision exceeded lowering by surface truncation and increased summit elevation and riftward flexing of the flank.

  15. Detrital apatite (U-Th)/He constraints on the exhumational histories of the Arunachal Pradesh Himalaya and the Shillong Plateau

    Science.gov (United States)

    Staisch, L. M.; Clark, M. K.; Niemi, N. A.; Avdeev, B.

    2010-12-01

    Erosion in the Himalaya is driven largely by a strongly coupled system of extreme climatic conditions and active tectonic processes. Spatial and temporal variations in erosion rates along strike are presumably controlled by differences in local climate, seismicity, deformation rates, and lithology. Quantifying the contribution of each of these parameters to the erosional budget of the Himalaya, however, is a nontrivial problem. The easternmost portion of the Himalayan arc offers a natural laboratory to explore the role of climatic influence on erosion rates. Deformation and uplift of the Shillong Plateau since ~8 Ma has created an orographic barrier ~400 km long that shields the eastern Himalaya, in Arunachal Pradesh, India, from a significant proportion of the precipitation carried by the South Asian Monsoon. Long-term exhumation rates derived from the Himalaya west and east of this orographic barrier have been shown to differ by a factor of ~2, a difference ascribed to reduced climatic forcing of erosion in the lee of the Shillong Plateau. Here we present apatite (U-Th)/He thermochronology data from modern detrital samples collected from northeast India. Between 18-20 single grain ages from each catchment were analyzed in order to calculate erosion rates on a 106 yr timescale. Recently developed Bayesian techniques for the inverse modeling of detrital data were used to derive time-temperature histories for each sample. Recent erosion rates modeled for a single south-facing catchment on the Shillong Plateau are modest, ~0.25 km Myr-1, and show a clear increase in exhumation rates at ~8 Ma from rates of indicate that the easternmost Himalaya, as a whole, experienced a significant increase in exhumation rate in the late Miocene, although the absolute rates are lower than observed throughout the Bhutanese and Nepalese Himalaya. The temporal correlation of this increase suggests a regional cause, possibly reflecting changes in the stress field across the India

  16. Phanerozoic polycyclic evolution of the southwestern Angola margin: New insights for apatite fission track and (U-Th)/He methodologies

    Science.gov (United States)

    Venancio da Silva, Bruno; Hackspacher, Peter; Carina Siqueira Ribeiro, Marli; Glasmacher, Ulrich Anton

    2016-04-01

    The low-temperature thermochronology has been an important tool to quantify geological process in passive continental margins. In this context, the Angolan margin shows evidence of a polycyclic post-rift evolution marked by different events of uplift, basin inversion and changes in sedimentation rates to the marginal basins, which have controlled the salt tectonics and the hydrocarbon deposits (1,2,3,4). To understand the post break-up evolution of the southwestern Angola margin, it were collected outcrop samples for apatite fission track (AFT) and (U-Th)/He analysis ranging in elevation from 79 m to 1675 m from the coast toward the interior plateau in a profile between Namibe and Lubango cities. The area lies on the edge of Central and Southern Atlantic segments a few kilometers northward the Walvis ridge and encompasses the Archean and Proterozoic basement rocks of the Congo craton. The AFT ages ranging from 120.6 ± 8.9 Ma to 328.8 ± 28.5 Ma and they show a trend of increasing age toward the Great Escarpment with some exceptions. The partial mean track lengths (MTLs) vary between 11.77 ± 1.82 μm to 12.34 ± 1.13 μm with unimodal track length distributions (TDLs). The partial (U-Th)/He ages ranging from 104.85 ± 3.15 Ma to 146.95 ± 4.41 Ma and show the same trend of increasing ages landward, little younger than the AFT ages, which could be interpreted as a fast exhumation episode in Late Jurassic - Early Cretaceous times. The thermal histories modelling has been constrained with the kinetic parameters Dpar (5) and c-axis angle (6) by the software Hefty (7). Both AFT and (U-Th)/He thermal histories modelling indicate three episodes of denudation/uplift driven cooling: (a) from Late Jurassic to Early Cretaceous, (b) a smallest one in the Late Cretaceous and (c) from Oligocene-Miocene to recent, which are compatible with geophysical data of the offshore Namibe basin that estimate the greater thickness of sediments formed in the first and third episodes

  17. Tracing the oxygen triple isotopic composition of tropospheric molecular oxygen in biogenic apatite - a new tool for palaeoclimatology

    Science.gov (United States)

    Pack, A.; Süssenberger, A.; Gehler, A.; Wotzlaw, J.

    2009-04-01

    It has been demonstrated that tropospheric molecular oxygen posses a significant isotope anomaly [1, 2 and refs. therein]. Relative to the rocks- and minerals-defined terrestrial fractionation line (TFL), tropospheric O2 has an anomaly of -0.35‰ [2]. Because almost all oxygen on Earth is contained in rocks, we suggest that the rocks- and minerals-defined TFL [3] should be used as reference when reporting isotope anomalies with ∆17O = δ'17OSMOW - βTFL δ'18OSMOW. We have developed a new technique for the determination of δ17O and δ18O of silicates by means of laser fluorination GC-CF-irmMS. We have determined βTFL to 0.5247 (N > 100), which is identical to the value reported by other laboratories and techniques [2, 3]. The uncertainty in ∆17O is ±0.03 (1σ) for a single analysis. It was suggested that ∆17O of tropospheric O2 can be used as proxy for the global bioactivity rate [GBR, 1] as well as for past atmospheric CO2 concentrations [4]. Past ∆17O of tropospheric O2 can be determined by analyzing O2 trapped in ice [1, 5] or by analyzing sulfates from terrestrial sulphide oxidation [4]. Disadvantage of ice core data is the limitation in time back Elephant). The ∆17O of apatite varies between -0.16‰ for a wood mouse (Apodemus sylvaticus) and +0.04‰ for a wild boar (Sus scrofa). Samples were analyzed between 5 and 7 times in order to reduce the analytical uncertainty to ±0.012-0.025‰. Our data confirm the prediction from mass balance that animals inherit a ∆17O signature from anomalous air O2. We have developed a detailed mass balance for mammals with respect to ∆17O. The mass balance considers the oxygen fluxes (drinking and food water, respired O2, metabolic water, excrements, evaporated water and exhaled CO2). The fractionation in δ18O and ∆17O (from associated β-value) was considered for each of the fluxes. The result is an allometric scaling model for ∆17O as function of log Mb. Predicted and measured data agree within the

  18. Crystallization and crystal properties of squid rhodopsin

    OpenAIRE

    Murakami, Midori; Kitahara, Rei; Gotoh, Toshiaki; Kouyama, Tsutomu

    2007-01-01

    Truncated rhodopsin from the retina of the squid Todarodes pacificus was extracted and crystallized by the sitting-drop vapour-diffusion method. Hexagonal crystals grown in the presence of octylglucoside and ammonium sulfate diffracted to 2.8 Å resolution.

  19. STUDY OF AN ASSESSMENT OF THE FATE OF CALCIUM HYDROXY APATITE BLOCK WITH CORTICO CANCELLOUS BONE GRAFT USED IN COMMUNITED FRACTURES OF LONG BONE OF LOWER LIMB

    Directory of Open Access Journals (Sweden)

    Ahmad

    2015-03-01

    Full Text Available INTRODUCTION: In recent years there has been an increasing interest in biologically active calcium phosphate ceramic materials for orthopaedic application. A number of materials from human, animal or non - biological sources have been used to fill defects with or without additional autogenus bone. It would be ideal to have bone substitute w hich is easily fabricated and preserved, is biocompatible with bone, and is biodegradable. The calcium phosphate system, and in particular hydroxyappatite (HA, has long been the subject of intensive investigation. MATERIAL AND METHODS: This observational two year study was undertaken at S.N. Medical College and Hospital, Agra (U.P.. The patients having the comminuted fracture of the long bone of lower limbs were treated with autogenus bone graft and calcium hydroxy Apatite bone block. Functional results w ere presented according to Klemm and Borner (1986 criteria. RESULTS: The total cases studied were 25 out of which 21 cases had fracture of both bones of leg and 4 were of fracture femur. The patients were aged between 15 to 70 years. Most of the patients were males and the common mode of injury was road traffic accident. An excellent result were seen in the majority 9(36% of patients while 8(32% patients showed a good result and 6(24% showed a fair result. 17(68% patients had compound fracture while 8( 32% patients were having closed fracture. CONCLUSION: Calcium Hydroxy Apatite is a suitable alternative to bone graft. There was no evidence of any foreign body reaction and infection at the Calcium Hydroxy Apatite implanted site. There was satisfactory h ealing of all the comminuted fractures. The movement of adjacent joints was nearly normal. No refracture was observed on follow up.

  20. Characterization of granulations of calcium and apatite in serum as pleomorphic mineralo-protein complexes and as precursors of putative nanobacteria.

    Directory of Open Access Journals (Sweden)

    John D Young

    Full Text Available Calcium and apatite granulations are demonstrated here to form in both human and fetal bovine serum in response to the simple addition of either calcium or phosphate, or a combination of both. These granulations are shown to represent precipitating complexes of protein and hydroxyapatite (HAP that display marked pleomorphism, appearing as round, laminated particles, spindles, and films. These same complexes can be found in normal untreated serum, albeit at much lower amounts, and appear to result from the progressive binding of serum proteins with apatite until reaching saturation, upon which the mineralo-protein complexes precipitate. Chemically and morphologically, these complexes are virtually identical to the so-called nanobacteria (NB implicated in numerous diseases and considered unusual for their small size, pleomorphism, and the presence of HAP. Like NB, serum granulations can seed particles upon transfer to serum-free medium, and their main protein constituents include albumin, complement components 3 and 4A, fetuin-A, and apolipoproteins A1 and B100, as well as other calcium and apatite binding proteins found in the serum. However, these serum mineralo-protein complexes are formed from the direct chemical binding of inorganic and organic phases, bypassing the need for any biological processes, including the long cultivation in cell culture conditions deemed necessary for the demonstration of NB. Thus, these serum granulations may result from physiologically inherent processes that become amplified with calcium phosphate loading or when subjected to culturing in medium. They may be viewed as simple mineralo-protein complexes formed from the deployment of calcification-inhibitory pathways used by the body to cope with excess calcium phosphate so as to prevent unwarranted calcification. Rather than representing novel pathophysiological mechanisms or exotic lifeforms, these results indicate that the entities described earlier as NB most

  1. Post pan-african denudation history of southwestern Madagascar during the complex rift-drift evolution of the island: new aspects from titanite and apatite fission track analyses

    Science.gov (United States)

    Emmel, B.; Jacobs, J.

    2003-04-01

    Titanite and apatite fission track (FT) thermochronology from 53 basement outcrops in southwest Madagascar reveal a protracted post Pan-African history of extensional tectonism, denudation and sedimentation. The titanite FT ages range between 276 ± 14 Ma and 379 ± 38 Ma. Apatite FT ages vary between 117 ± 26 Ma and 379 ± 19 Ma with mean track length scattering between 11.7 ± 0.59 μm and 13.74 ± 0.21 μm. Combined titanite and apatite FT data were used to calculate denudation rates. Samples from the paleo western margin of Madagascar along the N-S striking Pan-African Ejeda shear zone give above-average denudation rates (100-205 mMa-1) during Carboniferous times. The shear zone was probably reactivated during this times. In contrast the calculated denudation rates for samples from the interior of the island are moderate (25-120 mMa-1). Vitrinite reflectance data from the Sakoa coal area as well as titanite and apatite FT data imply that during the Permo-Triassic rifting, the areas along the paleo western margin that previously underwent fast denudation were buried by a sedimentary cover of up to ˜4.5 km. At this time, a graben developed further inland along the NW-SE striking transcontinental Bongolava-Ranotsara shear zone (BRSZ). Modelled time-temperature paths indicate that the area within the BRSZ remained cool and unaffected since Carboniferous times whereas the samples northeast and southwest of the BRSZ suggest phases of differential cooling during Permian-Triassic times. Seismic data from the Morondava basin indicate that during the Middle Jurassic drift between Madagascar and East-Africa a rift jump towards the west occurred. Modelled time-temperature histories of basement units from the paleo western margin, buried during Permo Triassic times, were exhumed during Jurassic times. This is most probably related with the modified rift kinematics and the associated southwest migration of the margin. Modelled time-temperature paths of all samples from

  2. Growth of dopamine crystals

    Science.gov (United States)

    Patil, Vidya; Patki, Mugdha

    2016-05-01

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  3. ALICE photon spectrometer crystals

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Members of the mechanical assembly team insert the last few crystals into the first module of ALICE's photon spectrometer. These crystals are made from lead-tungstate, a crystal as clear as glass but with nearly four times the density. When a high-energy particle passes through one of these crystals it will scintillate, emitting a flash of light allowing the energy of photons, electrons and positrons to be measured.

  4. Crystallization from Gels

    Science.gov (United States)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  5. Protein Crystal Based Nanomaterials

    Science.gov (United States)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  6. Artistic Crystal Creations

    Science.gov (United States)

    Lange, Catherine

    2008-01-01

    In this inquiry-based, integrative art and science activity, Grade 5-8 students use multicolored Epsom salt (magnesium sulfate) crystallizing solutions to reveal beautiful, cylindrical, 3-dimensional, needle-shaped structures. Through observations of the crystal art, students analyze factors that contribute to crystal size and formation, compare…

  7. Fabrication of nanotube arrays on commercially pure titanium and their apatite-forming ability in a simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); Chang, Yu-Chen [Department of Mechanical and Automation Engineering, Da-Yeh University, Taiwan, ROC (China); Ho, Wen-Fu, E-mail: fujii@nuk.edu.tw [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung, Taiwan, ROC (China)

    2015-02-15

    In this study, we investigated self-organized TiO{sub 2} nanotubes that were grown using anodization of commercially pure titanium at 5 V or 10 V in NH{sub 4}F/NaCl electrolyte. The nanotube arrays were annealed at 450 °C for 3 h to convert the amorphous nanotubes to anatase and then they were immersed in simulated body fluid at 37 °C for 0.5, 1, and 14 days. The purpose of this experiment was to evaluate the apatite-formation abilities of anodized Ti nanotubes with different tube diameters and lengths. The nanotubes that formed on the surfaces of Ti were examined using a field emission scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscope. When the anodizing potential was increased from 5 V to 10 V, the pore diameter of the nanotube increased from approximately 24–30 nm to 35–53 nm, and the tube length increased from approximately 590 nm to 730 nm. In vitro testing of the heat-treated nanotube arrays indicated that Ca-P formation occurred after only 1 day of immersion in simulated body fluid. This result was particularly apparent in the samples that were anodized at 10 V. It was also found that the thickness of the Ca-P layer increases as the applied potential for anodized c.p. Ti increases. The average thickness of the Ca-P layer on Ti that was anodized at 5 V and 10 V was approximately 170 nm and 190 nm, respectively, after immersion in simulated body fluid for 14 days. - Highlights: • TiO{sub 2} nanotube on Ti surface was formed by anodic oxidation in a NaCl/NH{sub 4}F solution. • TiO{sub 2} layers show a tube length of 590 nm and 730 nm at 5 V and 10 V, respectively. • After soaking in SBF, Ca-P layer completely covered the entire nanotubular surfaces. • The Ca-P layer was thicker on the Ti surface anodized at 10 V.

  8. Late stage thermal history of the Songliao Basin and its tectonic implications: Evidence from apatite fission track (AFT) analyses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Apatite Fission Track (AFT) data from the Songliao Basin indicates that the late stage tectonic movements in the Songliao Basin have zoning in space and episodes in time. The late stage tectonic movements started from the east part of the basin and migrated westward. AFT ages in the east part of the basin are older than those in the west part of the basin, suggesting that the uplift occurred earlier in the east than in the west. The denudation thickness in the east part of the basin is significantly greater than that in the centre and west. The thermal history evolved two episodes of rapid cooling and subsequent slow cooling processes. Age-depth relationship derived from the AFT data indicates a four-episode denudation history. Further Monte Carlo random simulation of the AFT data reveals the four changing points of the thermal evolution at 65 Ma, 43.5 Ma, 28 Ma and 15 Ma, respectively. The uplifting and denudation rates from different episodes of evolution are proportional to the plate convergence rate. Based on the above analyses and the regional geologic background, it is concluded that the late stage thermal events in the Songliao Basin are the far field response to the subduction of the Pacific Plate under the Eurasian Plate. The first episode of the rapid cooling probably started at the end of the Nenjiang Formation, climaxed at the end of the Cretaceous and ceased at the Late Eocene. The subsequent slow cooling lasts another 15 Ma. The first episode of the evolution is the far field response to the major episode of the Yanshan Movement and subsequent series of the tectonic reorganization, especially the directional change of the Pacific Movement and also the subduction of the Indian Plate underneath the Eurasian Plate. While the second episode of the evolution is the far field response to the extension and closure of the Sea of Japan. Extension led to the migration and converging of the mantle heat flow to the Sea of Japan and resulted in the rapid cooling

  9. Crystallization of accessory phases in magmas by local saturation adjacent to phenocrysts

    Science.gov (United States)

    Bacon, C.R.

    1989-01-01

    Accessory minerals commonly occur attached to or included in the major crystalline phases of felsic and some intermediate igneous rocks. Apatite is particularly common as inclusions, but Fe-Ti oxides, pyrrhotite, zircon, monazite, chevkinite and xenotime are also known from silicic rocks. Accessories may nucleate near the host crystal/ liquid interface as a result of local saturation owing to formation of a differentiated chemical boundary layer in which accessory mineral solubility would be lower than in the surrounding liquid. Differentiation of this boundary layer would be greatest adjacent to ferromagnesian phenocrysts, especially Fe-Ti oxides; it is with oxides that accessories are most commonly associated in rocks. A boundary layer may develop if the crystal grows more rapidly than diffusion can transport incorporated and rejected elements to and from the phenocryst. Diffusion must dominate over convection as a mode of mass transfer near the advancing crystal/liquid interface in order for a boundary layer to exist. Accumulation of essential structural constituent elements of accessory minerals owing to their slow diffusion in evolved silicate melt also may force local saturation, but this is not a process that applies to all cases. Local saturation is an attractive mechanism for enhancing fractionation during crystallization differentiation. If accessory minerals attached to or included in phenocrysts formed because of local saturation, their host phenocrysts must have grown rapidly when accessories nucleated in comparison to lifetimes of magma reservoirs. Some inconsistencies remain in a local saturation origin for accessory phases that cannot be evaluated without additional information. ?? 1989.

  10. Cooler for obtaining crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cabric, B.; Danilovic, N. [Faculty of Sciences, P.O. Box 60, 34000 Kragujevac (RS); Pavlovic, T. [Faculty of Sciences, P.O. Box 224, 18000 Nis (RS)

    2011-03-15

    A modular air-cooled tube, with a series of movable Tamman test tubes or plugs (modular unilateral and bilateral ''crystallization comb''), installed in a laboratory tube furnace is presented. The setup allows easy regulation and simultaneous crystallization tests of a series of different crystallization parameters in crucible columns, enabling rapid acquisition of crystals. The relationship between the crystallization parameters has been given and numerically analyzed. This method can also be applied in crucible and chamber furnaces. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Effect of ZrO(2) additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics.

    Science.gov (United States)

    Li, H C; Wang, D G; Meng, X G; Chen, C Z

    2014-06-01

    A series of ZrO(2) doped MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sedimentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca(5)(PO4)3F (fluorapatite) and β-CaSiO(3). (β-wollastonite). m-ZrO(2) (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO(2) (tetragonal zirconia) increased the crystallization temperature of Ca(5)(PO4)(3)F and declined the crystallization temperature of β-CaSiO(3). t-ZrO(2) greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell.

  12. Welding Molecular Crystals.

    Science.gov (United States)

    Adolf, Cyril R R; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-12-16

    Both for fundamental and applied sciences, the design of complex molecular systems in the crystalline phase with strict control of order and periodicity at both microscopic and macroscopic levels is of prime importance for development of new solid-state materials and devices. The design and fabrication of complex crystalline systems as networks of crystals displaying task-specific properties is a step toward smart materials. Here we report on isostructural and almost isometric molecular crystals of different colors, their use for fabrication of core-shell crystals, and their welding by 3D epitaxial growth into networks of crystals as single-crystalline entities. Welding of crystals by self-assembly processes into macroscopic networks of crystals is a powerful strategy for the design of hierarchically organized periodic complex architectures composed of different subdomains displaying targeted characteristics. Crystal welding may be regarded as a first step toward the design of new hierarchically organized complex crystalline systems. PMID:26581391

  13. Spatial variation in exhumation rates across Ladakh and the Karakoram: New apatite fission track data from the Eastern Karakoram, NW India

    Science.gov (United States)

    Wallis, David; Carter, Andrew; Phillips, Richard J.; Parsons, Andrew J.; Searle, Michael P.

    2016-03-01

    Characterization of low-temperature cooling histories and associated exhumation rates is critical for deciphering the recent evolution of orogenic regions. However, these may vary significantly over relatively short distances within orogens. It is pertinent therefore to constrain cooling histories and hence exhumation rates across major tectonic boundaries. We report the first apatite fission track ages from the Karakoram Fault Zone in the Eastern Karakoram range, which forms part of the western margin of the Tibetan Plateau. Ten samples, from elevations of 3477-4875 m, have apatite fission track dates from 3.3 ± 0.3 Ma to 7.4 ± 1.1 Ma. The ages correspond to modeled average erosional exhumation rates of 0.67 + 0.27/-0.18 mm/yr across the Eastern Karakoram. The results are consistent with a trend northward from the Indus suture zone, across the Ladakh terrane and into the Karakoram, in which tectonic uplift associated with crustal thickening increases toward the north, raising elevation and promoting glaciation and generation of extreme relief. As a result, erosion and exhumation rates increase south to north. Present-day precipitation on the other hand varies little within the study area and on a larger scale decreases southwest to northeast across this portion of the orogen. The Eastern Karakoram results highlight the diverse patterns of exhumation driven by regional variations in tectonic response to collision along the western margin of Tibet.

  14. A novel glass ionomer cement containing MgCO(3 )apatite induced the increased proliferation and differentiation of human pulp cells in vitro.

    Science.gov (United States)

    Laiteerapong, Arunee; Lochaiwatana, Yossakit; Hirata, Isao; Okazaki, Masayuki; Mori, Kenta; Murakami, Shinya; Poolthong, Suchit

    2012-01-01

    This study aimed to investigate the in vitro biological response of human dental pulp cells to glass ionomer cement (GIC, Fuji IX GP(®)) containing 2.5% magnesium carbonate apatite (MgCO(3)Ap). MgCO(3)Ap was synthesized by wet method and characterized using FT-IR, XPS, and SEM. Fuji IX GP(®) served as a control. Test and control cements were prepared by encapsulated mixing the powder with Fuji IX-liquid (P/L=3.6:1). Eluates from cements extracted by 1 mL culture medium were collected at day 1, 7 and 14, and used for WST-1 proliferation assay. For ALPase activity, cells were maintained with cements in transwells, harvested and enzyme activity was measured at day 1, 4, 7, 14, and 21. We found a higher cell proliferation and increased ALPase activity by pulp cells in the test group compared to the control. This suggests the potential of GIC containing this novel biological apatite as a restorative material for pulp-dentin regeneration. PMID:23037840

  15. Fe-O stable isotope pairs elucidate a high-temperature origin of Chilean iron oxide-apatite deposits

    Science.gov (United States)

    Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Lundstrom, Craig C.; Gajos, Norbert; Bindeman, Ilya; Barra, Fernando; Munizaga, Rodrigo

    2016-03-01

    Iron oxide-apatite (IOA) ore deposits occur globally and can host millions to billions of tons of Fe in addition to economic reserves of other metals such as rare earth elements, which are critical for the expected growth of technology and renewable energy resources. In this study, we pair the stable Fe and O isotope compositions of magnetite samples from several IOA deposits to constrain the source reservoir of these elements in IOAs. Since magnetite constitutes up to 90 modal% of many IOAs, identifying the source of Fe and O within the magnetite may elucidate high-temperature and/or lower-temperature processes responsible for their formation. Here, we focus on the world-class Los Colorados IOA in the Chilean iron belt (CIB), and present data for magnetite from other Fe oxide deposits in the CIB (El Laco, Mariela). We also report Fe and O isotopic values for other IOA deposits, including Mineville, New York (USA) and the type locale, Kiruna (Sweden). The ranges of Fe isotopic composition (δ56Fe, 56Fe/54Fe relative to IRMM-14) of magnetite from the Chilean deposits are: Los Colorados, δ56Fe (±2σ) = 0.08 ± 0.03‰ to 0.24 ± 0.08‰; El Laco, δ56Fe = 0.20 ± 0.03‰ to 0.53 ± 0.03‰; Mariela, δ56Fe = 0.13 ± 0.03‰. The O isotopic composition (δ18O, 18O/16O relative to VSMOW) of the same Chilean magnetite samples are: Los Colorados, δ18O (±2σ) = 1.92 ± 0.08‰ to 3.17 ± 0.03‰; El Laco, δ18O = 4.00 ± 0.10‰ to 4.34 ± 0.10‰; Mariela, δ18O = (1.48 ± 0.04‰). The δ18O and δ56Fe values for Kiruna magnetite yield an average of 1.76 ± 0.25‰ and 0.16 ± 0.07‰, respectively. The Fe and O isotope data from the Chilean IOAs fit unequivocally within the range of magnetite formed by high-temperature magmatic or magmatic-hydrothermal processes (i.e., δ56Fe 0.06-0.49‰ and δ18O = 1.0-4.5‰), consistent with a high-temperature origin for Chilean IOA deposits. Additionally, minimum formation temperatures calculated by using the measured Δ18O

  16. Macromolecular crystallization in microgravity

    Energy Technology Data Exchange (ETDEWEB)

    Snell, Edward H [Biophysics Group, NASA Marshall Space Flight Center, Code XD42, Huntsville, AL 35812 (United States); Helliwell, John R [Department of Chemistry, The University of Manchester, Manchester, M13 9PL (United Kingdom)

    2005-04-01

    Density difference fluid flows and sedimentation of growing crystals are greatly reduced when crystallization takes place in a reduced gravity environment. In the case of macromolecular crystallography a crystal of a biological macromolecule is used for diffraction experiments (x-ray or neutron) so as to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal then the greater the molecular structure detail that can be extracted. It is this structural information that enables an understanding of how the molecule functions. This knowledge is changing the biological and chemical sciences, with major potential in understanding disease pathologies. In this review, we examine the use of microgravity as an environment to grow macromolecular crystals. We describe the crystallization procedures used on the ground, how the resulting crystals are studied and the knowledge obtained from those crystals. We address the features desired in an ordered crystal and the techniques used to evaluate those features in detail. We then introduce the microgravity environment, the techniques to access that environment and the theory and evidence behind the use of microgravity for crystallization experiments. We describe how ground-based laboratory techniques have been adapted to microgravity flights and look at some of the methods used to analyse the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural advances. Finally, limitations and alternatives to microgravity and future directions for this research are covered. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry and mathematics meet to enable insight to the fundamentals of life. As the reader will see, there is a great deal of physics involved when the microgravity environment is applied to crystallization, some of it known, and undoubtedly much yet to

  17. Photonic Crystal Waveguide Fabrication

    OpenAIRE

    Høvik, Jens

    2012-01-01

    This research is entirely devoted to the study and fabrication of structures with periodic dielectric constants, also known as photonic crystals (PhCs). These structures show interesting dispersion characteristics which give them a range of prohibited frequencies that are not allowed to propagate within the crystal. This property makes them suited for a wide array of photonic-based components. One-dimensional photonic crystals are already commercialized and are of widespread use in for exampl...

  18. Ion Coulomb Crystals

    CERN Document Server

    Thompson, Richard C

    2014-01-01

    Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.

  19. Holographic liquid crystal devices

    OpenAIRE

    Pavani, Kotakonda, (Thesis)

    2009-01-01

    Liquid crystals have become natural candidates for use in electro-optic devices for their ability to change the orientation of the director with the application of an electric field, and exhibiting large range of refractive index. The aim of the work presented in this thesis is to fabricate liquid crystal optoelectronic devices such as electrically switchable liquid crystal diffraction gratings and polarization rotators by exploiting the holographic surface relief effect in photopolymer and b...

  20. A crystal barrel

    CERN Multimedia

    2007-01-01

    The production of crystals for the barrel of the CMS electromagnetic calorimeter has been completed. This is an important milestone for the experiment, which received the last of its 62,960 crystals on 9 March. The members of the team responsible for the crystal acceptance testing at CERN display the last crystal for the CMS electromagnetic calorimeter barrel. From left to right: Igor Tarasov, Etiennette Auffray and Hervé Cornet.One of the six machines specially developed to measure 67 different parameters on each crystal. Igor Tarasov is seen inserting the last batch of crystals into the machine. The last of the 62,960 CMS barrel crystals arrived at CERN on 9 March. Once removed from its polystyrene protection, this delicate crystal, like thousands of its predecessors, will be inserted into the last of the 36 supermodules of the barrel electromagnetic calorimeter in a few days' time. This marks the end of an important chapter in an almost 15-year-long journey by the CMS crystals team, some of whose member...

  1. Crystallization Formulation Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Crystallization Formulation Lab fills a critical need in the process development and optimization of current and new explosives and energetic formulations. The...

  2. Automation in biological crystallization.

    Science.gov (United States)

    Stewart, Patrick Shaw; Mueller-Dieckmann, Jochen

    2014-06-01

    Crystallization remains the bottleneck in the crystallographic process leading from a gene to a three-dimensional model of the encoded protein or RNA. Automation of the individual steps of a crystallization experiment, from the preparation of crystallization cocktails for initial or optimization screens to the imaging of the experiments, has been the response to address this issue. Today, large high-throughput crystallization facilities, many of them open to the general user community, are capable of setting up thousands of crystallization trials per day. It is thus possible to test multiple constructs of each target for their ability to form crystals on a production-line basis. This has improved success rates and made crystallization much more convenient. High-throughput crystallization, however, cannot relieve users of the task of producing samples of high quality. Moreover, the time gained from eliminating manual preparations must now be invested in the careful evaluation of the increased number of experiments. The latter requires a sophisticated data and laboratory information-management system. A review of the current state of automation at the individual steps of crystallization with specific attention to the automation of optimization is given.

  3. Phononic crystal devices

    Science.gov (United States)

    El-Kady, Ihab F.; Olsson, Roy H.

    2012-01-10

    Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

  4. Tunable plasmonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

  5. Crystal Packing Analysis of Rhodopsin Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lodowski, D.T.; Salom, D.; Trong, I.Le; Teller, D.C.; Ballesteros, J.A.; Palczewski, K.; Stenkamp, R.E.; /Basel U. /Texas U. /Scripps Res. Inst.

    2007-07-10

    Oligomerization has been proposed as one of several mechanisms to regulate the activity of G protein-coupled receptors (GPCRs), but little is known about the structure of GPCR oligomers. Crystallographic analyses of two new crystal forms of rhodopsin reveal an interaction surface which may be involved in the formation of functional dimers or oligomers. New crystallization conditions lead to the formation of two crystal forms with similar rhodopsin-rhodopsin interactions, but changes in the crystal lattice are induced by the addition of different surfactant additives. However, the intermolecular interactions between rhodopsin molecules in these crystal structures may reflect the contacts necessary for the maintenance of dimers or oligomers in rod outer segment membranes. Similar contacts may assist in the formation of dimers or oligomers in other GPCRs as well. These new dimers are compared with other models proposed by crystallography or EM and AFM studies. The inter-monomer surface contacts are different for each model, but several of these models coincide in implicating helix I, II, and H-8 as contributors to the main contact surface stabilizing the dimers.

  6. Cenozoic evolution of tectono-fluid and metallogenic process in Lanping Basin,western Yunnan Province, Southwest China: Constraints from apatite fission track data

    Institute of Scientific and Technical Information of China (English)

    LI Xiaoming; SONG Yougui

    2006-01-01

    Since the Mesozoic, abundant metal and salt deposits have been formed in the Lanping Basin, western Yunnan Province, Southwest China, constituting a well-known hydrothermal ore belt in China. Most of the deposits are meso-epithermal hydrothermal deposits. This paper preliminarily deals with the mineralization ages of hydrothermal deposits in the Lanping Basin by using the apatite fission track method, and integrates the spatial distribution of the deposits and their regional geological backgrounds, to give the preliminary viewpoints as follows: (1) the apatite fission track ages acquired range from 19.9 Ma to 52.8 Ma, much younger than those of their host strata, so they may be considered to be mineralization ages, which represent the late mineralization period; (2) the apatite fission track ages tend to become younger from the west to the middle of the basin, indicating that the latest evolution of tectono-fluid and/or metallogenic processes of the middle basin ended later than that in the west; (3) in the Paleogene, most of the Cu deposits were formed in the western part of the basin; (4) the major metallogenic processes occur between the Paleogene and the Neogene, because the eastern and western edges of the basin were subducted into and collided with its bilateral continental blocks, respectively, and the central fault was strongly activated, which led to the processes of large-scale ore-forming fluids, and their differentiation and transport because of the variation of their physical and chemical properties. Having been squeezed and uplifted, the Lanping Basin became an intermontane basin that contains many kinds of fluid traps resulting in the formation of different types of ore deposits (for example, Pb-Zn, Cu, Ag) of different scales in the middle of the basin. Simultaneously, the fluids with volatile elements such as Hg, Sb and As were transported upwards along the central fault system and diffused into its subordinate fractures, thus leading to the

  7. Low-temperature exhumation history of Variscan-age rocks in the western Cantabrian Mountains (NW Spain) recorded by apatite fission-track data

    Science.gov (United States)

    Grobe, René W.; Alvarez-Marrón, Joaquina; Glasmacher, Ulrich A.; Menéndez-Duarte, Rosana

    2010-06-01

    This paper presents the first regional study of apatite fission-track (AFT) thermochronology to be undertaken in the western termination of the Cantabrian Mountains (NW Spain). The mountains reach elevations of over 2600 m along the northern coast of Spain and are comprised of a Variscan crustal section uplifted due to Cenozoic shortening along the northern Iberian Plate. The study constrains the pattern and history of exhumation within the Paleozoic bedrock over the past c. 240 Ma. Twenty-one apatite fission-track samples range in age from 246.7 (± 26.9) Ma to 78.1 (± 3.7) Ma, with mean track lengths between 10.4 (± 1.8) µm and 12.4 (± 1.4) µm. Time-temperature path modelling of the data indicates that different rates of continuous cooling took place during the three main tectonic events that affected the area. A rapid cooling event that ended by the Late Jurassic corresponds to topographic decay during unroofing of the Variscan orogen and the break-up of Pangea, and is responsible for the largest amount of exhumation. Westernmost samples cooled coinciding with rifting in the North Atlantic and Bay of Biscay during the Late Jurassic to Early Cretaceous. By about 100-80 Ma most samples had reached, or passed through, the upper boundary of the apatite partial annealing zone, which indicate that regional denudation has not exceeded c. 1.7 km since then, for geothermal gradients ≥ 27 °C/km and a surface temperature of 15 °C. Only three samples next to fault escarpments in the west cooled below 70 °C since 80 Ma, reaching below 65 °C before initiation of incipient subduction along the northern Iberian Margin by 46 Ma. An average cooling rate of ≤ 1 °C/Ma reflects latest denudation as the new mountainous relief developed since then due to shortening and incipient subduction associated with convergence along the northern Iberian Plate. The Cantabrian Mountains are one of the few natural examples of a coastal orogen in a juvenile stage of evolution.

  8. Preparation of an apatite-based matrix for the confinement of iodine 129; Mise au point d`une matrice apatitique pour le confinement de l`iode 129

    Energy Technology Data Exchange (ETDEWEB)

    Audubert, F.

    1995-11-08

    The aim of this thesis is the study of the conditioning of iodine 129 from the reprocessing of nuclear wastes. Because of its long half life (1.57 10{sup 7} years), the conditioning of iodine 129 requires a matrix stable during several thousands of years. The study of natural minerals allows the selection of mineral phases having a good long term behaviour. In the first part the policy of nuclear wastes management, and in particular of iodine, is recalled. A naturalistic approach is used to define the best conditioning material and the remarkable properties of apatite in this way are described. In the second part, the preparation and physical-chemical characterization of iodo-apatites are described. A demonstration is made that iodine can penetrate inside vanadate or lead phospho-vanadate apatite-based compounds. The third part deals with the preparation of the conditioning material. The sintering reaction under pressure allows the preparation of composite ceramics including iodo-apatite. A multi-layer coating process is defined: coating of PbI{sub 2} with a Pb{sub 3}(VO{sub 4}){sub 1.6}(PO{sub 4}){sub 0.4} layer and a Ca{sub 10}(PO{sub 4}){sub 6}F{sub 2} layer. Sintering is performed at 700 deg. celsius under a 25 MPa pressure. (J.S.). 131 refs.

  9. Channeling through Bent Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  10. Titanite and apatite fission track analyses on basement rocks of central-southern Madagascar: constraints on exhumation and denudation rates along the eastern rift shoulder of the Morondava basin

    Science.gov (United States)

    Emmel, B.; Jacobs, J.; Razakamanana, T.

    2004-03-01

    Titanite and apatite fission-track (FT) thermochronology from basement rocks in central-southern Madagascar reveals a protracted post Late Neoproterozoic/Early Cambrian history of extensional tectonism, denudation and sedimentation. Titanite FT ages range between 379 ± 38 and 276 ± 17 Ma and apatite FT ages vary between 379 ± 19 and 150 ± 8 Ma. Combined titanite and apatite FT data from the western palaeo margin of Madagascar suggest denudation rates of ˜200-100 mMa -1 during Carboniferous times. The Late Neoproterozoic/Early Cambrian Ejeda shear zone was probably reactivated during this time. In contrast, for the same period denudation rates inland are ˜110-25 mMa -1. During Permo-Triassic rifting, areas that previously underwent fast denudation were buried by sedimentary cover up to ˜4.5 km. At this time, a graben developed along the transcontinental Bongolava-Ranotsara shear zone (BRSZ). Graben faults are exposed at the northeastern graben shoulder. Identical titanite and apatite FT ages close to the BRSZ indicate rapid cooling associated with fluid circulation during Early Permian times. The initial Gondwana break-up during Middle Jurassic times and the drift of Madagascar along the Davie transform fault did not significantly influence the FT data and had only minor geomorphic impact in the study area. Only the far southwestern part of the island is characterised by a higher degree of denudation (max. ˜3.5 km) during Early Jurassic times. Early Cretaceous and Cenozoic volcanic activity affected the apatite FT data from southern Madagascar. Modelled time-temperature ( T- t) paths argue for a reheating of samples from southern Madagascar to temperatures of ˜60-80 °C during the times of magmatism, before final cooling to surface temperatures.

  11. Long-term landscape evolution of the South Atlantic "passive" continental margin in Eastern Argentina using apatite fission-track thermochronology

    Science.gov (United States)

    Pfister, Sabrina; Kollenz, Sebastian; Glasmacher, Ulrich A.

    2015-04-01

    To understand the evolution of the "passive" continental margin in Argentina low temperature thermochronology is an appropriate method, which might lead to new insights in this area. The Tandilia System, also called Sierras Septentrionales, is located south of the Río de la Plato Craton in eastern Argentina in the state of Buenos Aires. North of the hills the Salado basin is located whereas the Claromecó basin is situated south of the mountain range. In contrary to most basins along the South American "passive" continental margin, the Tandilia-System and the neighbouring basins trend perpendicular to the coast line. The topography is fairly flat with altitudes up to 350 m. The igneous-metamorphic basement is pre-Proterozoic in age and build up of mainly granitic-tonalitic gneisses, migmatites, amphibolites, some ultramafic rocks and granitoid plutons. It is overlain by a series of Neoproterozoic to early Paleozoic sedimentary rocks (Cingolani 2011), like siliciclastic rocks, dolostones, shales and limestones (Demoulin 2005). The aim of the study is to quantify the long-term landscape evolution of the "passive" continental margin in eastern Argentina in terms of thermal, exhumation and tectonic evolution. For that purpose, samples were taken from the basement of the Sierra Septentrionales and analyzed with the apatite fission-track method. Further 2-D thermokinematic modeling was conducted with the computer code HeFTy (Ketcham 2005; Ketcham 2007; Ketcham et al. 2009). Because there are different hypotheses in literature regarding the geological evolution of this area two different models were generated, one after Demoulin et al. (2005) and another after Zalba et al.(2007). All samples were taken from the Neoproterozoic igneous-metamorphic basement. Apatite fission-track ages range from 101.6 (9.4) to 228.9 (22.3) Ma, and, therefore, are younger than their formation age, indicating all samples have been thermally reset. Six samples accomplished enough confined

  12. Tectonomorphic evolution of the Eastern Cordillera fold-thrust belt, Colombia: New insights based on apatite and zircon (U-Th)/He thermochronometers

    Science.gov (United States)

    Ghorbal, B.; Stockli, D. F.; Mora, A.; Horton, B. K.; Blanco, V.; Sanchez, N.

    2010-12-01

    The Eastern Cordillera (EC) of Colombia marks the eastern boundary of Cenozoic fold-thrust deformation in the northern Andes. It is a classic example of an inversion belt formed in the retro-arc region, in this case superimposed on a Triassic/Jurassic to Cretaceous intracontinental rift system of northern South America. Ongoing thrust reactivation (inversion) in this contractional orogen provides an excellent opportunity to study the patterns of deformation and influence of preexisting anisotropies (Mora et al., 2006). The objective of this detailed (U-Th)/He study is to unravel the tectonic and thermal evolution of the EC from the Magdalena Valley basin in the west to the Llanos foreland basin in the east and reconstruct the temporal and spatial progression of deformation in the EC fold-thrust belt. Furthermore, the Subandean or foothills zone of Colombia is key for understanding the petroleum systems in the complex frontal zone of the inverted fold-thrust belt. We present detailed apatite and zircon (U-Th)/He thermochronometric data from surface samples along a ~220 km WNW-ESE transect across the EC from the frontal fold-thrust belt at the edge of the Llanos basin to the western edge of the EC, the Magdalena basin. Surface and borehole zircon and apatite (U-Th)/He data, integrated with structural data, show that the EC fold-thrust belt propagated foreland-ward from the axial zone to the modern edges of the fold-thrust belt from at least the early Oligocene to the early Miocene. Detailed apatite and zircon (U-Th)/He data from surface samples and borehole samples in the foothills-Llanos transition zone and the Middle Magdalena Valley basin, between the large-displacement Guaicaramo and Pajarito-Chámeza thrusts in the east and the La Salina fault system in the west show a temporally complex evolution. The frontal fold-thrust belt was characterized by continued progressive foreland-ward migration of deformation and an apparent phase of major out-of-sequence motion

  13. FIELD TEST INSTRUCTION 100-NR-2 OPERABLE UNIT DESIGN OPTIMIZATION STUDY FOR SEQUESTRATION OF SR-90 SATURATED ZONE APATITE PERMEABLE REACTIVE BARRIER EXTENSION

    Energy Technology Data Exchange (ETDEWEB)

    BOWLES NA

    2010-10-06

    The objective of this field test instruction is to provide technical guidance for aqueous injection emplacement of an extension apatite permeable reactive barrier (PRE) for the sequestration of strontium-90 (Sr-90) using a high concentration amendment formulation. These field activities will be conducted according to the guidelines established in DOE/RL-2010-29, 100-NR-2 Design Optimization Study, hereafter referred to as the DOS. The DOS supports the Federal Facility Agreement Consent Order (EPA et al., 1989), Milestone M-16-06-01, and 'Complete Construction of a Permeable Reactive Barrier at 100-N.' Injections of apatite precursor chemicals will occur at an equal distance intervals on each end of the existing PRE to extend the PRB from the existing 91 m (300 ft) to at least 274 m (900 ft). Field testing at the 100-N Area Apatite Treatability Test Site, as depicted on Figure 1, shows that the barrier is categorized by two general hydrologic conceptual models based on overall well capacity and contrast between the Hanford and Ringold hydraulic conductivities. The upstream portion of the original barrier, shown on Figure 1, is characterized by relatively low overall well specific capacity. This is estimated from well development data and a lower contrast in hydraulic conductivity between the Hanford formation and Ringold Formations. Comparison of test results from these two locations indicate that permeability contrast between the Hanford formation and Ringold Formation is significantly less over the upstream one-third of the barrier. The estimated hydraulic conductivity for the Hanford formation and Ringold Formation over the upstream portion of the barrier based on observations during emplacement of the existing 91 m (300 ft) PRB is approximately 12 and 10 m/day (39 and 32 ft/day), respectively (PNNL-17429). However, these estimates should be used as a rough guideline only, as significant variability in hydraulic conductivity is likely to be observed in

  14. Crystal growth and crystallography

    Science.gov (United States)

    Chernov, A. A.

    1998-01-01

    Selected topics that may be of interest for both crystal-structure and crystal-growth communities are overviewed. The growth of protein crystals, along with that of some other compounds, is one of the topics, and recent insights into related phenomena are considered as examples of applications of general principles. The relationship between crystal growth shape and structure is reviewed and an attempt to introduce semiquantitative characterization of binding for proteins is made. The concept of kinks for complex structures is briefly discussed. Even at sufficiently low supersaturations, the fluctuation of steps may not be sufficient to implement the Gibbs-Thomson law if the kink density is low enough. Subsurface ordering of liquids and growth of rough interfaces from melts is discussed. Crystals growing in microgravity from solution should be more perfect if they preferentially trap stress-inducing impurities, thus creating an impurity-depleted zone around themselves. Evidently, such a zone is developed only around the crystals growing in the absence of convection. Under terrestrial conditions, the self-purified depleted zone is destroyed by convection, the crystal traps more impurity and grows stressed. The stress relief causes mosaicity. In systems containing stress-inducing but poorly trapped impurities, the crystals grown in the absence of convection should be worse than those of their terrestrial counterparts.

  15. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D;

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  16. Crystals in the LHC

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Bent crystals can be used to deflect charged particle beams. Their use in high-energy accelerators has been investigated for almost 40 years. Recently, a bent crystal was irradiated for the first time in the HiRadMat facility with an extreme particle flux, which crystals would have to withstand in the LHC. The results were very encouraging and confirmed that this technology could play a major role in increasing the beam collimation performance in future upgrades of the machine.   UA9 bent crystal tested with a laser. Charged particles interacting with a bent crystal can be trapped in channelling states and deflected by the atomic planes of the crystal lattice (see box). The use of bent crystals for beam manipulation in particle accelerators is a concept that has been well-assessed. Over the last three decades, a large number of experimental findings have contributed to furthering our knowledge and improving our ability to control crystal-particle interactions. In modern hadron colliders, su...

  17. Photonic Crystal Fiber Attenuator

    Institute of Scientific and Technical Information of China (English)

    Joo Beom Eom; Hokyung Kim; Jinchae Kim; Un-Chul Paek; Byeong Ha Lee

    2003-01-01

    We propose a novel fiber attenuator based on photonic crystal fibers. The difference in the modal field diameters of a conventional single mode fiber and a photonic crystal fiber was used. A variable optical attenuator was also achieved by applying macro-bending on the PCF part of the proposed attenuator

  18. Walkout in Crystal City

    Science.gov (United States)

    Barrios, Greg

    2009-01-01

    When students take action, they create change that extends far beyond the classroom. In this article, the author, who was a former teacher from Crystal City, Texas, remembers the student walkout that helped launch the Latino civil rights movement 40 years ago. The Crystal City student walkout remains a high point in the history of student activism…

  19. Apatite (U-Th)/He Thermochronometry as an innovative Geothermal Exploration Tool - A case study from the Wassuk Range, Hawthorne, Nevada

    Science.gov (United States)

    Gorynski, K. E.; Stockli, D. F.; Walker, J. D.

    2010-12-01

    A utility-grade geothermal system requires increased, near-surface temperatures (>120°C), water to transfer heat, and structural or sedimentological fluid conduits. In extensional tectonic settings, geothermal anomalies often occur in areas with recent, high strain accumulation and complex faulting (i.e., cross-faults, accommodation zones) where exhumation and uplift of footwall rocks transfer heat, via advection, to the near-surface which is further carried by water through structural fluid conduits. Apatite helium (AHe) thermochronometric footwall age mapping can be used in conjunction with these genetic occurrence models to further focus regional-scale geothermal exploration efforts to areas of probabilistic increased fracture permeability and most recent, rapid footwall exhumation. Furthermore, partially reset apatites resulting from interaction with hydrothermal fluids (>40°C) will show which areas have been hottest most recently. This case study in the Wassuk Range, Hawthrone, NV confirms the utility of AHe thermochronometry as a geothermal exploration tool. A dense grid of footwall samples were collected adjacent to the Hawthorne geothermal anomaly (>85°C BHT) located in the hanging wall of the Wassuk Range block. Our data show that the location of the present-day geothermal anomaly correlates with the location of 1) the most recent episode of rapid footwall exhumation at 3.5-4 Ma, 2) km scale accommodation zones between differentially tilted Wassuk Range blocks, and 3) an elevated Miocene geothermal gradient. Furthermore, anomalously young AHe ages (Hawthorne geothermal anomaly and likely resulted from interaction with a deep-seated geothermal cell or hot hydrothermal fluids.

  20. Biomimetically Ornamented Rapid Prototyping Fabrication of an Apatite-Collagen-Polycaprolactone Composite Construct with Nano-Micro-Macro Hierarchical Structure for Large Bone Defect Treatment.

    Science.gov (United States)

    Wang, Jinbing; Wu, Dingyu; Zhang, Zhanzhao; Li, Jun; Shen, Yi; Wang, Zhenxing; Li, Yu; Zhang, Zhi-Yong; Sun, Jian

    2015-12-01

    Biomaterial-based bone graft substitute with favorable mechanical and biological properties could be used as an alternative to autograft for large defect treatment. Here, an apatite-collagen-polycaprolactone (Ap-Col-PCL) composite construct was developed with unique nano-micro-macro hierarchical architectures by combining rapid prototyping (RP) fabrication technology and a 3D functionalization strategy. Macroporous PCL framework was fabricated using RP technology, then functionalized by collagen incorporation and biomimetic deposition. Ap-Col-PCL composite construct was characterized with hierarchical architectures of a nanoscale (∼100 nm thickness and ∼1 μm length) platelike apatite coating on the microporous (126 ± 18 μm) collagen networks, which homogeneously filled the macroporous (∼1000 μm) PCL frameworks and possessed a favorable hydrophilic property and compressive modulus (68.75 ± 3.39 MPa) similar to that of cancellous bone. Moreover, in vitro cell culture assay and in vivo critical-sized bone defect implantation demonstrated that the Ap-Col-PCL construct could not only significantly increase the cell adhesion capability (2.0-fold) and promote faster cell proliferation but also successfully bridge the segmental long bone defect within 12 weeks with much more bone regeneration (5.2-fold), better osteointegration (7.2-fold), and a faster new bone deposition rate (2.9-fold). Our study demonstrated that biomimetically ornamented Ap-Col-PCL constructs exhibit a favorable mechanical property, more bone tissue ingrowth, and better osteointegration capability as an effective bone graft substitute for critical-sized bone defect treatment; meanwhile, it can also harness the advantages of RP technology, in particular, facilitating the customization of the shape and size of implants according to medical images during clinical application.

  1. In Vitro Screening of the Apatite-Forming Ability, Biointeractivity and Physical Properties of a Tricalcium Silicate Material for Endodontics and Restorative Dentistry

    Directory of Open Access Journals (Sweden)

    Maria Giovanna Gandolfi

    2013-12-01

    Full Text Available Aim: Calcium silicate-based materials are hydraulic self-setting materials with physico-chemical properties suitable for endodontic surgery and good biological/clinical outcomes. The study aim was to evaluate the bio-properties (biointeractivity and apatite-forming ability and selected physical properties (porosity, water sorption, solubility, and setting time of Biodentine, a tricalcium silicate material for endodontics and restorative dentistry, compared to that of ProRoot MTA (Mineral Trioxide Aggregate as gold standard material. Methods: Biodentine and ProRoot MTA pastes were prepared and analyzed for calcium release and alkalinizing activity (3 h–28 days, setting time, water sorption, porosity, solubility, surface microstructure and composition, and apatite-forming ability in simulated body fluid. Results: Biodentine showed higher calcium release, alkalinizing activity, and solubility but higher open and apparent porosity, water sorption, and a markedly shorter setting time. Calcium phosphate (CaP deposits were noted on material surfaces after short ageing times. A CaP coating composed of spherulites was detected after 28 days. The thickness, continuity, and Ca/P ratio of the coating differed markedly between the materials. Biodentine showed a coating composed by denser but smaller spherulites, while ProRoot MTA showed large but less dense aggregates of spherulitic deposits. Conclusions: Biodentine showed a pronounced ability to release calcium and extended alkalinizing activity interlinked with its noticeable porosity, water sorption, and solubility: open porosities provide a broad wet biointeractive surface for the release of the calcium and hydroxyl ions involved in the formation of a CaP mineral. Biodentine is a biointeractive tricalcium silicate material with interesting chemical-physical properties and represents a fast-setting alternative to the conventional calcium silicate MTA-like cements.

  2. Multi-phase Uplift of the Indo-Burman Ranges and Western Thrust Belt of Minbu Sub-basin (West Myanmar): Constraints from Apatite Fission Track Data

    Science.gov (United States)

    Zhang, P.; Qiu, H.; Mei, L.

    2015-12-01

    The forearc regions in active continental margins are important keys to analysis geodynamic processes such as oceanic crust oblique subduction, mechanism of subduction zone, and sediments recycling. The West Myanmar, interpreted as forearc silver, is the archetype example of such forearc regions subordinate to Sunda arc-trench system, and is widely debated when and how its forearc regions formed. A total of twenty-two samples were obtained from the Indo-Burman Ranges and western thrust belt of Minbu Sub-basin along Taungup-Prome Road in Southwestern Myanmar (Figure 1), and five sandstone samples of them were performed at Apatite to Zircon, Inc. Three samples (M3, M5, and M11) collected from Eocene flysch and metamorphic core at the Indo-Burman Ranges revealed apatite fission track (AFT) ages ranging from 19 to 9 Ma and 6.5 to 2 Ma. Two samples (M20 and M21) acquired from the western thrust belt of Minbu Sub-basin yielded AFT ages ranging from 28 to 13.5 Ma and 7.5 to 3.5 Ma. Time-temperature models based on AFT data suggest four major Cenozoic cooling episodes, Late Oligocene, Early to Middle Miocene, Late Miocene, and Pliocene to Pleistocene. The first to third episode, models suggest the metamorphic core of the Indo-Burman Ranges has experienced multi-phase rapidly uplifted during the early construction of the forearc regions. The latest episode, on which this study focused, indicated a fast westward growth of the Palaeogene accretionary wedge and a eastward propagation deformation of folding and thrusting of the western thrust belt of Minbu Sub-basin. We argued that above multi-phase uplifted and deformation of the forearc regions were results of India/West Burma plate's faster oblique convergence and faster sedimentation along the India/Eurasia suture zone.

  3. Active Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Ek, Sara

    This thesis deals with the fabrication and characterization of active photonic crystal waveguides, realized in III-V semiconductor material with embedded active layers. The platform offering active photonic crystal waveguides has many potential applications. One of these is a compact photonic...... crystal semiconductor optical amplier. As a step towards such a component, photonic crystal waveguides with a single quantum well, 10 quantum wells and three layers of quantum dots are fabricated and characterized. An experimental study of the amplied spontaneous emission and a implied transmission...... are presented in this thesis. A variation of photonic crystal design parameters are used leading to a spectral shift of the dispersion, it is veried that the observed effects shift accordingly. An enhancement of the amplified spontaneous emission was observed close to the band edge, where light is slowed down...

  4. Optically Anomalous Crystals

    CERN Document Server

    Shtukenberg, Alexander; Kahr, Bart

    2007-01-01

    Optical anomalies in crystals are puzzles that collectively constituted the greatest unsolved problems in crystallography in the 19th Century. The most common anomaly is a discrepancy between a crystal’s symmetry as determined by its shape or by X-ray analysis, and that determined by monitoring the polarization state of traversing light. These discrepancies were perceived as a great impediment to the development of the sciences of crystals on the basis of Curie’s Symmetry Principle, the grand organizing idea in the physical sciences to emerge in the latter half of the 19th Century. Optically Anomalous Crystals begins with an historical introduction covering the contributions of Brewster, Biot, Mallard, Brauns, Tamman, and many other distinguished crystallographers. From this follows a tutorial in crystal optics. Further chapters discuss the two main mechanisms of optical dissymmetry: 1. the piezo-optic effect, and 2. the kinetic ordering of atoms. The text then tackles complex, inhomogeneous crystals, and...

  5. Crystallization phenomena of isotactic polystyrene

    NARCIS (Netherlands)

    Lemstra, Peter Jan

    1975-01-01

    In this thesis the crystallization behavior of isotactic polystyrene has been described. The kinetics of the crystallization process and the crystalline structure were studied both for crystallization in the bulk and from dilute solutions. ... Zie Summary

  6. Magnetic ions in crystals

    CERN Document Server

    Stevens, K W

    2014-01-01

    There have been many demonstrations, particularly for magnetic impurity ions in crystals, that spin-Hamiltonians are able to account for a wide range of experimental results in terms of much smaller numbers of parameters. Yet they were originally derived from crystal field theory, which contains a logical flaw; electrons on the magnetic ions are distinguished from those on the ligands. Thus there is a challenge: to replace crystal field theory with one of equal or greater predictive power that is based on a surer footing. The theory developed in this book begins with a generic Hamiltonian, on

  7. Raman scattering in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.F.

    1988-09-30

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  8. Friction between incommensurate crystals

    OpenAIRE

    Friedel, Jacques; De Gennes, Pierre-Gilles

    2006-01-01

    Abstract We present an overview of friction processes expected between two ideal crystals of strong layers (graphite, MoS?u...) when one crystal is rotated with respect to the other by a certain angle Ye. We assume perfect conditions: no impurities; no preexisting dislocations in the bulk of the crystals; slow gliding velocities. Two regimes show up: a) weak coupling when Ye>U?u/U_{L}, where U?u (U_{L}) are typical intra (inter) layer interactions. Here we expect weak friction, con...

  9. Molecules in crystals

    Science.gov (United States)

    Spackman, Mark A.

    2013-04-01

    Hirshfeld surface analysis has developed from the serendipitous discovery of a novel partitioning of the crystal electron density into discrete molecular fragments, to a suite of computational tools used widely for the identification, analysis and discussion of intermolecular interactions in molecular crystals. The relationship between the Hirshfeld surface and very early ideas on the internal structure of crystals is outlined, and applications of Hirshfeld surface analysis are presented for three molecules of historical importance in the development of modern x-ray crystallography: hexamethylbenzene, hexamethylenetetramine and diketopiperazine.

  10. The Crystal Hotel: A Microfluidic Approach to Biomimetic Crystallization.

    Science.gov (United States)

    Gong, Xiuqing; Wang, Yun-Wei; Ihli, Johannes; Kim, Yi-Yeoun; Li, Shunbo; Walshaw, Richard; Chen, Li; Meldrum, Fiona C

    2015-12-01

    A "crystal hotel" microfluidic device that allows crystal growth in confined volumes to be studied in situ is used to produce large calcite single crystals with predefined crystallographic orientation, microstructure, and shape by control of the detailed physical environment, flow, and surface chemistry. This general approach can be extended to form technologically important, nanopatterned single crystals. PMID:26479157

  11. Crystallization Growth of Single Crystal Cu by ContinuousCasting

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Crystallization growth of single-crystal Cu by continuous casting has been investigated using selfdesigned horizontal continuous casting equipment and XRD. Experimental results showed that the crystallization plane of (311), (220) and (111) were eliminated sequentially in evolutionary process. The final growth plane of crystal was (200), the direction of crystallization was [100],the growth direction of both sides of the rod inclined to axis, and the degree of deviation of direction [100] from the crystal axis was less than 10. In order to produce high quality single crystal, the solid-liquid interface morphology must be smooth, even be planar.

  12. Dynamics in liquid crystals

    International Nuclear Information System (INIS)

    Five types of reorientational motions for molecules in liquid crystals are discussed on the basis of a comparison of the neutron scattering and the dielectric relaxation methods. 18 refs., 7 figs., 2 tabs. (author)

  13. Crystal Electrostatic Energy

    CERN Document Server

    Ivanchin, Alexander

    2010-01-01

    It has been shown that to calculate the parameters of the electrostatic field of the ion crystal lattice it sufficient to take into account ions located at a distance of 1-2 lattice spacings. More distant ions make insignificant contribution. As a result, the electrostatic energy of the ion lattice in the alkaline halide crystal produced by both positive and negative ions is in good agreement with experiment when the melting temperature and the shear modulus are calculated. For fcc and bcc metals the ion lattice electrostatic energy is not sufficient to obtain the observed values of these parameters. It is possible to resolve the contradiction if one assumes that the electron density is strongly localized and has a crystal structure described by the lattice delta - function. As a result, positive charges alternate with negative ones as in the alkaline halide crystal. Such delta-like localization of the electron density is known as a model of nearly free electrons.

  14. Inclusions in DKDP crystal

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The shape and the size of inclusions in DKDP crystal have been observed and measured microscopically.Three kinds of inclusions were found and the components of the inclusions were measured. The formation mechanisms were proposed and discussed.``

  15. Living liquid crystals

    OpenAIRE

    Zhou, Shuang; Sokolov, Andrey; Lavrentovich, Oleg D.; Aranson, Igor S.

    2014-01-01

    Collective motion of self-propelled organisms or synthetic particles often termed active fluid has attracted enormous attention in broad scientific community because of it fundamentally non-equilibrium nature. Energy input and interactions among the moving units and the medium lead to complex dynamics. Here we introduce a new class of active matter, living liquid crystals (LLCs) that combine living swimming bacteria with a lyotropic liquid crystal. The physical properties of LLCs can be contr...

  16. Characterizing protein crystal nucleation

    Science.gov (United States)

    Akella, Sathish V.

    We developed an experimental microfluidic based technique to measure the nucleation rates and successfully applied the technique to measure nucleation rates of lysozyme crystals. The technique involves counting the number of samples which do not have crystals as a function of time. Under the assumption that nucleation is a Poisson process, the fraction of samples with no crystals decays exponentially with the decay constant proportional to nucleation rate and volume of the sample. Since nucleation is a random and rare event, one needs to perform measurements on large number of samples to obtain good statistics. Microfluidics offers the solution of producing large number of samples at minimal material consumption. Hence, we developed a microfluidic method and measured nucleation rates of lysozyme crystals in supersaturated protein drops, each with volume of ˜ 1 nL. Classical Nucleation Theory (CNT) describes the kinetics of nucleation and predicts the functional form of nucleation rate in terms of the thermodynamic quantities involved, such as supersaturation, temperature, etc. We analyzed the measured nucleation rates in the context of CNT and obtained the activation energy and the kinetic pre-factor characterizing the nucleation process. One conclusion is that heterogeneous nucleation dominates crystallization. We report preliminary studies on selective enhancement of nucleation in one of the crystal polymorprhs of lysozyme (spherulite) using amorphous mesoporous bioactive gel-glass te{naomi06, naomi08}, CaO.P 2O5.SiO2 (known as bio-glass) with 2-10 nm pore-size diameter distribution. The pores act as heterogeneous nucleation centers and claimed to enhance the nucleation rates by molecular confinement. The measured kinetic profiles of crystal fraction of spherulites indicate that the crystallization of spherulites may be proceeding via secondary nucleation pathways.

  17. Crystal Structures of Furazanes

    OpenAIRE

    Klapötke, Thomas; Schmid, Philipp; Stierstorfer, Jörg

    2015-01-01

    Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and BAM (Bundesanstalt für Materialforschung und -prüfung) methods. The standard enthalpies of formation were calculated for all...

  18. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    Energy Technology Data Exchange (ETDEWEB)

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  19. Fractal Photonic Crystal Waveguides

    OpenAIRE

    Monsoriu, Juan A.; Zapata-Rodriguez, Carlos J.; Silvestre, Enrique; Furlan, Walter D.

    2004-01-01

    We propose a new class of one-dimensional (1D) photonic waveguides: the fractal photonic crystal waveguides (FPCWs). These structures are photonic crystal waveguides (PCWs) etched with fratal distribution of grooves such as Cantor bars. The transmission properties of the FPCWs are investigated and compared with those of the conventional 1D PCWs. It is shown that the FPCW transmission spectrum has self-similarity properties associated with the fractal distribution of grooves. Furthermore, FPCW...

  20. Building a crystal palace

    CERN Multimedia

    2007-01-01

    The end-caps of the CMS electromagnetic calorimeter (ECAL) take shape as the first quadrant was completed on Wednesday 3 October. 1831 crystals, organised into five by five blocks named ‘supercrystals’, make up the first quadrant of Dee 1.With the 61,200-crystal barrel of its electromagnetic calorimeter (ECAL) complete, CMS is now building the endcaps, on the tenth anniversary of their initial design. Crystals for the endcaps were the last to be made, so the race is now on to have them all in place and ready for the turn-on of the LHC next year. Assembly of the first of eight quadrants began in June and crystal mounting was completed on Wednesday 3 October. Each crystal is transparent, has a volume just larger than a CERN coffee cup yet weighs a huge 1.5kg. 1831 of these lead tungstate crystals went into the first quadrant from a total 14,648 in the endcaps. The lead and tungsten account for 86% of each crystal’s weight, but as project leader Dave Cockerill expl...

  1. Crystal growth of artificial snow

    Science.gov (United States)

    Kimura, S.; Oka, A.; Taki, M.; Kuwano, R.; Ono, H.; Nagura, R.; Narimatsu, Y.; Tanii, J.; Kamimiytat, Y.

    1984-01-01

    Snow crystals were grown onboard the space shuttle during STS-7 and STS-8 to facilitate the investigation of crystal growth under conditions of weightlessness. The experimental design and hardware are described. Space-grown snow crystals were polyhedrons looking like spheres, which were unlike snow crystals produced in experiments on Earth.

  2. Engineering of recombinant crystallization chaperones

    OpenAIRE

    Koide, Shohei

    2009-01-01

    The preparation of diffraction quality crystals remains the major bottleneck in macromolecular x-ray crystallography. A crystallization chaperone is an auxiliary protein, such as fragments of monoclonal antibodies, that binds to and increases the crystallization probability of a target molecule of interest. Such chaperones reduce conformational heterogeneity, mask counterproductive surfaces while extending surfaces predisposed to forming crystal contacts, and provide phasing information. Crys...

  3. Experimental study of kinetic and mechanism of dissolution of apatite structured minerals. Application to the prediction of the long term behavior of an actinides storage host matrix; Etude experimentale de la cinetique et des mecanismes d'alteration de mineraux apatitiques. Application au comportement d'une ceramique de confinement d'actinides mineurs

    Energy Technology Data Exchange (ETDEWEB)

    Chairat, C

    2005-11-15

    The motivation for this study is to assess the potential of using apatite structured ceramics as long-lived actinide storage hosts. To assess their ability to resist aqueous corrosion, the dissolution of natural fluoro-apatite and synthetic Nd-britholite (neodymium is a proxy for the trivalent actinides) was studied. Mineral surfaces were characterized using a combined spectrometric, electrokinetic and potentiometric approach and dissolution rates were measured in closed and open system reactors as a function of solution composition. Experimental results suggest apatitic minerals dissolve via distinct step sequence: 1) fluoride release, 2) release of the calcium situated in the M1, and 3) the simultaneous removal of phosphate and calcium II via the breaking of only Ca-O bonds. TST based rate equations based in this mechanism accurately describe fluoro-apatite and synthetic britholite dissolution rates as a function of solution composition. Nd release rates are limited by precipitation of Nd-rhabdophane. (author)

  4. New constraints on paleo-denudation history of the Ladakh Batholith - applying bedrock and detrital apatite (U-Th-Sm)/He thermochronology

    Science.gov (United States)

    Sahragard Sohi, Mohammad; Rosenkranz, Ruben; Spiegel, Cornelia

    2015-04-01

    The Ladakh Batholith is part of the Transhimalayan Plutonic Belt and records the early exhumation history of the Himalayan orogen. The evolution of the Ladakh Batholith is complex and was controversially discussed in the literature (see Kirstein, 2011 for details). Recent data by Kirstein et al. (2006 & 2009) suggest a trend of exhumation rates across the batholith, with earlier exhumation along its southern margin and later exhumation in the north. Apart from methodological purpose aimed at refining the apatite (U-Th-Sm)/He technique, the goal of our study is to investigate the earliest denudation history of the Ladakh Pluton and thereby that of the Himalayan orogen, using apatite (U-Th-Sm)/He thermochronology (i) applied to bedrocks from the southern margin of the batholith, and (ii) to sediments from the adjacent Upper Indian Group sediments such as Nurla, Choksti, and Nimu Formations with Early Eocene to Late Miocene in age (Henderson et al., 2010). These sediments are thought to be sourced from the Ladakh Batholith (Henderson et al., 2011). Apatite (U-Th-Sm)/He dating is sensitive to temperatures between ~85 and 40°C and thus to geodynamic movements of the upper ~1.5 to 3 km of the earth's crust. While thermochronology data from present-day bedrock exposures provides denudation rates integrated over the time between cooling age and the present, the earlier denudation history is eroded away from the present exposures and stored in the syn-tectonic sediments. Thus, dating sediments of the Indian Group will yield the paleo-denudation history of the (southern) Ladakh area, including changes of denudation rates back through time. This will reveal new insights into the relation between tectonics, climate, and erosion. References Henderson, A. L., Y. Najman, R. Parrish, M. BouDagher - Fadel, D. Barford, E. Garzanti, and S. Andò (2010), Geology of the Cenozoic Indus Basin sedimentary rocks: Paleoenvironmental interpretation of sedimentation from the western Himalaya

  5. Origin and evolution of ore-forming fluids in the Hemushan magnetite-apatite deposit, Anhui Province, Eastern China, and their metallogenic significance

    Science.gov (United States)

    Luo, Gan; Zhang, Zhiyu; Du, Yangsong; Pang, Zhenshan; Zhang, Yanwen; Jiang, Yongwei

    2015-12-01

    The Middle-Lower Yangtze River Metallogenic Belt in the northern Yangtze Block is one of the most important economic mineral districts in China. The Hemushan deposit is a medium-class Fe deposit located in the southern part of the Ningwu iron ore district of the Middle-Lower Yangtze River Metallogenic Belt. The Fe-orebodies are mainly hosted in the contact zone between diorite and Triassic marble. The actinolite-phlogopite-apatite-magnetite ore shows metasomatic/filling textures and disseminated/mesh-vein structures. Based on evidences and petrographic observations, the ore-forming process can be divided into three distinct periods-the early metallogenic period (albite-diopside stage), the middle metallogenic period (magnetite stage and hematite stage), and the late metallogenic period (quartz-pyrite stage and carbonate stage). Fluid inclusion studies show four types of inclusions: type I daughter mineral-bearing three-phase inclusions (L + V + S), type II vapor-rich two-phase inclusions (L + V), type III liquid-rich two phase inclusions (L + V), and minor type IV liquid-phase inclusions (L). Apatites from the magnetite stage contain type I, type II and type III inclusions; anhydrites from the hematite stage mainly contain abundant type II inclusions and relatively less type I inclusions; quartz and calcite from the late metallogenic stage are mainly characterized by type III inclusions. Laser Raman spectroscopy and microthermometry of fluid inclusions show that the ore-forming fluids broadly correspond to unsaturated NaCl-H2O system. From the magnetite stage to the carbonate stage, the ore-forming fluids evolved from moderate-high temperature (average 414 °C), moderate salinity (average 25.01 wt.% NaCl equiv.) conditions to low temperature (average 168 °C), low salinity (average 6.18 wt.% NaCl equiv.) conditions. Hydrogen and oxygen isotopic studies indicate that the ore-forming fluid during the early stage of middle metallogenic period was mainly of magmatic

  6. Apatite layer growth on glassy Zr48Cu36Al8Ag8 sputtered titanium for potential biomedical applications

    Science.gov (United States)

    Thanka Rajan, S.; Karthika, M.; Bendavid, Avi; Subramanian, B.

    2016-04-01

    The bioactivity of magnetron sputtered thin film metallic glasses (TFMGs) of Zr48Cu36Al8Ag8 (at.%) on titanium substrates was tested for bio implant applications. The structural and elemental compositions of TFMGs were analyzed by XRD, XPS and EDAX. X-ray diffraction analysis displayed a broad hump around the incident angle of 30-50°, suggesting that the coatings possess a glassy structure. An in situ crystal growth of hydroxyapatite was observed by soaking the sputtered specimen in simulated body fluid (SBF). The nucleation and growth of a calcium phosphate (Ca-P) bone-like hydroxyapatite on Zr48Cu36Al8Ag8 (at.%) TFMG from SBF was investigated by using XRD, AFM and SEM. The presence of calcium and phosphorus elements was confirmed by EDAX and XPS. In vitro electrochemical corrosion studies indicated that the Zr-based TFMG coating sustain in the stimulated body-fluid (SBF), exhibiting superior corrosion resistance with a lower corrosion penetration rate and electrochemical stability than the bare crystalline titanium substrate.

  7. Adsorption of Pb(II) present in aqueous solution on calcium, strontium and barium hydroxy apatites; Adsorcion de Pb(II) presente en solucion acuosa sobre hidroxiapatitas de calcio, estroncio y bario

    Energy Technology Data Exchange (ETDEWEB)

    Vilchis G, J.

    2013-07-01

    Calcium, strontium and barium hydroxy apatites were successfully synthesized by chemical precipitation method, the obtained powders were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscopy (Sem), semi-quantitative elemental analysis (EDS), infrared spectroscopy (IR), and N{sub 2} physisorption studies, complementary to these analytical techniques, was determined the surface fractal dimension (Df), and the amount of surface active sites of the materials, in order to know application as ceramic for water remediation. The ability of Pb(II) ion adsorption present in aqueous solution on the hydroxy apatites synthesized by batch type experiments was studied as a function of contact time, concentration of the adsorbate and temperature. The maximum lead adsorption efficiencies obtained were 0.31, 0.32 and 0.26 mg/g for calcium, strontium and barium hydroxy apatites respectively, achieved an equilibrium time of 20 minutes in the three solid-liquid systems studied. Experimental data were adequately adjusted at the adsorption kinetic model pseudo-second order, for the three cases. Moreover, experimental data of the strontium and calcium hydroxy apatites were adjusted to the Langmuir adsorption isotherm, indicating that the adsorption was through a monolayer, whereas barium hydroxyapatite was adjusted to the Freundlich adsorption isotherm, indicating a multilayer adsorption. The thermodynamic parameters obtained during adsorption studies as a function of temperature showed physisorption, exothermic and spontaneous processes respectively. The results showed that the calcium hydroxyapatite, strontium and barium are an alternative for the Pb(II) ion adsorption present in wastewaters. (Author)

  8. Thermal history and age of geological regions obtained by applying the fission track method in apatite samples; Historia termica e idades de regioes geologicas obtidas atraves de tracos de fissao em apatita

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Cleber J.; Tello Saenz, Carlos A.; Balan, Ana M. Osorio A.; Dias, Airton N.C.; Novaes, Felipe P.; Oliveira, Roger D.; Barra, Beatriz C., E-mail: pccj13@yahoo.com.b, E-mail: amoa@fct.unesp.b [UNESP, Presidente Prudente, SP (Brazil). Dept. de Fisica, Quimica e Biologia

    2007-07-01

    The objective of this work is dating apatite samples using the Fission Track Method (FTM). Samples were collected from different altitudes in Serra da Mantiqueira (Brazil): High Mantiqueira (above 1,000 m) and Low Mantiqueira (below 1,000 m). Data obtained for the ages and thermal history of the samples via FTM have been interpreted and, according to the geological point of view, can be associated with the uplifting of Serra da Mantiqueira after the opening of the Atlantic Ocean

  9. Photonic Crystal Microchip Laser

    Science.gov (United States)

    Gailevicius, Darius; Koliadenko, Volodymyr; Purlys, Vytautas; Peckus, Martynas; Taranenko, Victor; Staliunas, Kestutis

    2016-09-01

    The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality. Experiments show that a microchip laser, due to spatial filtering functionality of intracavity photonic crystal, improves the beam quality factor M2 reducing it by a factor of 2, and increase the brightness of radiation by a factor of 3. This comprises a new kind of laser, the “photonic crystal microchip laser”, a very compact and efficient light source emitting high spatial quality high brightness radiation.

  10. Frequency doubling crystals

    Science.gov (United States)

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  11. Flexible ferroelectric organic crystals

    Science.gov (United States)

    Owczarek, Magdalena; Hujsak, Karl A.; Ferris, Daniel P.; Prokofjevs, Aleksandrs; Majerz, Irena; Szklarz, Przemysław; Zhang, Huacheng; Sarjeant, Amy A.; Stern, Charlotte L.; Jakubas, Ryszard; Hong, Seungbum; Dravid, Vinayak P.; Stoddart, J. Fraser

    2016-10-01

    Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity--the properties that originate from their non-centrosymmetric crystal lattice--but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals.

  12. Flexible ferroelectric organic crystals

    Science.gov (United States)

    Owczarek, Magdalena; Hujsak, Karl A.; Ferris, Daniel P.; Prokofjevs, Aleksandrs; Majerz, Irena; Szklarz, Przemysław; Zhang, Huacheng; Sarjeant, Amy A.; Stern, Charlotte L.; Jakubas, Ryszard; Hong, Seungbum; Dravid, Vinayak P.; Stoddart, J. Fraser

    2016-01-01

    Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity—the properties that originate from their non-centrosymmetric crystal lattice—but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals. PMID:27734829

  13. Pseudomorphic replacement of single cerussite PbCO3 crystals by hydroxylpyromorphite Pb5(PO4)3OH in phosphate solutions

    Science.gov (United States)

    Kwaśniak-Kominek, M.; Manecki, M.; Bajda, T.; Rakovan, J.

    2012-04-01

    Lead apatite, pyromorphite, can form by replacing lead carbonate, cerussite, under conditions similar to those found in earth surface environments. This occurs by a process analogous to the calcium carbonate - calcium apatite system, where during chemical weathering and natural hydrothermal reactions hydroxylapatite can form by replacing calcium carbonates. The aim of this study is to experimentally investigate reactions of cerussite with phosphate solutions to determine the conditions under which pyromorphite can form and the mechanism of the transformation. Cerussite can be readily transformed into hydroxylpyromorphite by hydrothermal treatment in a 2M (NH4)H2PO4 solution. The product of reactions is independent of the presence of Cl in the solution. Hydrothermal experiments were carried out in order to produce partially reacted crystals. In both cases, with the presence or absence of Cl, the cerussite is pseudomorphologically replaced by hydroxylpyromorphite. The reaction products were studied by scanning electron microscopy (SEM) to determine the microstructural relationship between the parent and the product phases. X-Ray powder diffraction (XRD) and infra-red spectroscopy (FTIR) were used for phase determination. The results show that the new phase was only hydroxylpyromorphite even in the presence of Cl. Observations of broken crystals show partial replacement of cerussite by polycrystalline hydroxylpyromorphite, preventing even fine scale surface micromorphology. The features of replacement of cerussite crystals by hydroxylpyromorphite are similar to pseudomorphic reactions in a wide range of materials and are consistent with a mechanism described as interface-coupled dissolution-precipitation. This project is partially financed by Polish NCN grant No UMO-211/01/M/ST10/06999.

  14. Instabilities in liquid crystals

    International Nuclear Information System (INIS)

    This thesis contains theoretical work dealing with the effects of magnetic and electric fields on samples of nematic, smectic A and smectic C liquid crystals. Some background material along with the continuum theory is introduced in Chapter 2. In Chapter 3 we consider the effect on the director within an infinite sample of nematic liquid crystal which is subjected to crossed electric and magnetic fields. In particular we examine the stability of the travelling waves which describe the director motion by considering the behaviour of the stable perturbations as time increases. The work of Chapter 4 examines a bounded sample of smectic A liquid crystal in two dimensions which is subjected to a magnetic field. It can be shown that layer undulations may occur after a critical threshold is reached. The effects of various forms of pressure are also studied and in the case when pressure is included it is shown that layer undulations will always occur regardless of the field strength. Chapter 5 extends the work of Chapter 4 to three dimensions. We consider the effect of adding a dynamical term and study the stability of these solutions. Also we examine how the layers undulate when the sample of smectic A liquid crystal is confined to various cylindrical geometries and subjected to a magnetic field and a uniform pressure. In Chapter 6 we consider a sample of smectic C liquid crystal which is subjected to an oscillatory electric field. The motion of the c-director is complicated and we examine the differences which occur for differing dielectric anisotropies. Finally, in Chapter 7 we study how a sample of smectic C liquid crystal behaves when it is subjected to a uniform shear flow within the smectic plane. We find travelling wave solutions for the behaviour of the c-director and adapt these solutions to incorporate the effects of an applied field. (author)

  15. Thermal history from Pocos de Caldas alkaline massif, SP/MG , Brazil and dyke rich margins using apatite fission track analysis

    International Nuclear Information System (INIS)

    The South American Platform in southeastern Brazil records a long history of tectonic magmatic and uplift events, which resulted from the opening of the South Atlantic Ocean, Cretaceous reactivation and epirogeneic processes. Specific manifestations include the basic magmatism of the Serra Geral Formation of the Parana Basin and alkaline magmatism of Pocos de Caldas - Cabo Frio Lineament, as well as the uplift of the Serra da Mantiqueira and Serra do Mar mountain ranges. Thermo tectonic and geochronological studies using the K-Ar method and apatite fission track analysis in samples of the Pocos de Caldas alkaline massif show an initial evolution beginning 89 Ma related to a tectonic uplift, interpreted as related to the intrusion's doming. This was followed by an important episode of rapid cooling related to the formation of the massif. At the same time, the mountains that surround the massif record heating events in response to the alkaline intrusion, between 70 and 50 Ma. Periods of slow uplift, probably related to the South American Erosion Cycle (between 50 and 30 Ma) and Velhas Erosion Cycle (from 25 Ma), indicate a strong manifestation of denudation in this area. (author)

  16. Thermal history of the Jurassic Strata in the Northern Tianshan and its geological significance, revealed by apatite fission-track and vitrinite-reflectance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.C.; Guo, Z.J.; Wu, C.D.; Fang, S.H. [Peking University, Beijing (China)

    2007-07-15

    Apatite fission track (AFT) dating is carried on 18 samples collected from Shichang-Manas, Anjihai river and Sikesu area of the Northern margin of Tianshan. Vitrinite reflectance (R{sub o}) data of 10 samples from the Triassic to Jurassic coal seam were obtained to provide maximum paleotemperatures for the stratigraphic strata experiencing. The data suggest that maximum burial and thermal maturity of the Triassic and lower Jurassic rocks occurred at Late Jurassic to Early Cretaceous, and then retained at the same depth till Miocene. This history is consistent with the AFT modeling result of the underlying granite. The cooling of Late Jurassic to Early Cretaceous can be typically interpreted as the result of decreasing of paleothermal gradient at the Cretaceous. The burial and heating of the Middle Jurassic rocks preserved for a long time until late Oligocene. All AFT samples show evidence for Miocene rapid cooling, beginning at about 10 Ma. This cooling is typically interpreted as the result of uplift and erosion of overlying strata. Miocene cooling of Mesozoic and Paleozoic granite suggests that uplift of the northern Tianshan occurred significantly later than previously proposed and is consistent with timing of intense deformation in the southwestern Junggar basin.

  17. Effects of Apatite Cement Containing Atelocollagen on Attachment to and Proliferation and Differentiation of MC3T3-E1 Osteoblastic Cells

    Directory of Open Access Journals (Sweden)

    Masaaki Takechi

    2016-04-01

    Full Text Available To improve the osteoconductivity of apatite cement (AC for reconstruction of bone defects after oral maxillofacial surgery, we previously fabricated AC containing atelocollagen (AC(ate. In the present study, we examined the initial attachment, proliferation and differentiation of mouse osteoblastic cells (MC3T3-E1 cells on the surface of conventional AC (c-AC, AC(ate and a plastic cell dish. The number of osteoblastic cells showing initial attachment to AC(ate was greater than those attached to c-AC and similar to the number attached to the plastic cell wells. We also found that osteoblastic cells were well spread and increased their number on AC(ate in comparison with c-AC and the wells without specimens, while the amount of procollagen type I carboxy-terminal peptide (PIPC produced in osteoblastic cells after three days on AC(ate was greater as compared to the others. There was no significant difference in regard to alkaline phosphatase (ALP activity and osteocalcin production by osteoblastic cells among the three surface types after three and six days. However, after 12 days, ALP activity and the produced osteocalcin were greater with AC(ate. In conclusion, AC(ate may be a useful material with high osteoconductivity for reconstruction of bone defects after oral maxillofacial surgery.

  18. Non-cytotoxic organic-inorganic hybrid bioscaffolds: An efficient bedding for rapid growth of bone-like apatite and cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    John, Lukasz, E-mail: lukasz.john@chem.uni.wroc.pl [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw (Poland); Baltrukiewicz, Marta; Sobota, Piotr [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw (Poland); Brykner, Renata; Cwynar-Zajac, Lucja [Department of Histology and Embryology, Wroclaw Medical University, 6a Chalubinskiego, 50-368 Wroclaw (Poland); Dziegiel, Piotr [Department of Histology and Embryology, Wroclaw Medical University, 6a Chalubinskiego, 50-368 Wroclaw (Poland); Department of Histology and Embryology, Poznan University of Medical Sciences, 6 Swiecickiego, 61-781 Poznan (Poland)

    2012-10-01

    Synthesis and characterization of organic-inorganic macroporous hybrid scaffolds were investigated. The materials were prepared by combining 2-hydroxyethylmethacrylate (HEMA) and triethoxyvinylsilane (TEVS) chemically modified by Ca{sup 2+} and PO{sub 4}{sup 3-} ions via sol-gel route. In this study we have constructed a sugar-based cracks-free three-dimensional (3D) network with interconnected porous architecture within the range of 150-300 {mu}m and rough topography. The obtained results revealed that both topography and composition of prepared materials allow rapid growth of the bone-like apatite (HAp) layer on their surface after soaking in biological medium. Preliminary studies have shown that hybrids covered by HAp are non-cytotoxic and allow cell proliferation that make them a promising scaffolds in the field of bone regenerative medicine. The materials were mainly characterized by powder X-ray diffraction analysis (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and transmission electron microscopy-energy-dispersive spectroscopy (TEM-EDS). Highlights: Black-Right-Pointing-Pointer Sol-gel derived biomaterials. Black-Right-Pointing-Pointer 3D organic-inorganic hybrid composites for bone tissue engineering. Black-Right-Pointing-Pointer Sugar-templated cracks-free macroporous scaffolds. Black-Right-Pointing-Pointer 2-hydroxyethylmethacrylate/triethoxyvinylsilane blend doped with calcium and phosphate ions. Black-Right-Pointing-Pointer Non-cytotoxic bedding for fibroblasts proliferation.

  19. Relevance of the choice of spark plasma sintering parameters in obtaining a suitable microstructure for iodine-bearing apatite designed for the conditioning of I-129

    Energy Technology Data Exchange (ETDEWEB)

    Campayo, L., E-mail: lionel.campayo@cea.fr [CEA, DEN, DTCD/SECM/LDMC – Marcoule, F-30207 Bagnols-sur-Cèze (France); Le Gallet, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-UB, 9 Av. Alain Savary, BP 47870, 21078 Dijon Cedex (France); Perret, D.; Courtois, E. [CEA, DEN, DTCD/SECM/LDMC – Marcoule, F-30207 Bagnols-sur-Cèze (France); Cau Dit Coumes, C. [CEA, DEN, DTCD/SPDE/LP2C – Marcoule, F-30207 Bagnols-sur-Cèze (France); Grin, Yu. [Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden (Germany); Bernard, F. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-UB, 9 Av. Alain Savary, BP 47870, 21078 Dijon Cedex (France)

    2015-02-15

    Highlights: • Modeling of reactive sintering by SPS of an iodoapatite for waste immobilization. • Use of a statistical approach to surmount the complexity of the process. • The supposed most resistant microstructure towards leaching is obtained at 450 °C. • Pressure has no influence in the liquid sintering regime. - Abstract: The high chemical durability of iodine-bearing apatite phases makes them potentially attractive for immobilizing radioactive iodine. Reactive spark plasma sintering provides a dense ceramic as a wasteform. A design-of-experiments (DOE) approach was adopted to identify the main process/material parameters and their first order interactions in order to specify experimental conditions guaranteeing complete reaction, relative density of the wasteform exceeding 92% and the largest possible grain size. For a disposal of the wasteform in a deep geological repository, these characteristics allow minimization of the iodine release by contact with groundwater. It was found that sintering at a temperature of 450 °C with an initial specific surface area of 3.3 m{sup 2} g{sup −1} for the powder reactants is sufficient in itself to achieve the targeted characteristics of the wasteform. However, this relies on a liquid sintering regime the efficiency of which can be limited by the lead iodide initial content in the mix as well as by its particle size.

  20. Stability of Lead Immobilized by Apatite in Lead-Containing Rhizosphere Soil of Buckwheat (Fagopyrum esculentum) and Hairy Vetch (Vicia villosa).

    Science.gov (United States)

    Katoh, Masahiko; Matsuoka, Hideaki; Sato, Takeshi

    2015-01-01

    This study conducted plant growth experiments using a rhizobox system to understand the growth of buckwheat and hairy vetch as well as the stability of lead immobilized by hydroxyapatite (HAP) in the lead-containing rhizosphere soil. The shoot dry weight of buckwheat did not significantly differ between the lead-containing rhizosphere soil with and without HAP, whereas that of hairy vetch with rhizosphere soil without HAP was reduced. Lead was not accumulated from the rhizosphere soil to the shoots of either plant when HAP was added. The percentage of each lead fraction in sequential extraction was approximately the same through the 3 mm of rhizosphere soils from the root surface and non-planted soil, with and without the addition of HAP. For hairy vetch, the amount of water-soluble lead in the HAP-added rhizosphere soil within 3 mm thickness from the root surface did not increase. However, for buckwheat, the amount of water-soluble lead in the HAP-added rhizosphere soil 1 mm from the root surface increased to the same level as that in the non-planted soil without HAP. Our results suggest that when applying phytostabilization combined with apatite to lead-contaminated soil, the plant that cannot re-mobilize lead should be selected. PMID:25747247

  1. Electronic structure, elastic anisotropy, thermal conductivity and optical properties of calcium apatite Ca5(PO4)3X (X = F, Cl or Br)

    International Nuclear Information System (INIS)

    Highlights: • The degree of elastic anisotropy is ordered as follows BrA > ClA > FA. • The thermal conductivity in (112¯0) plane is smaller than in (0 0 0 1) plane. • The refractive indexes for FA, ClA and BrA are 1.17, 1.19 and 1.21, respectively. - Abstract: The density-functional theory with the generalized gradient approximation was performed to investigate the structural properties, phase stability, electronic structure, elastic properties, and optical properties of selected Ca5(PO3)4F (FA), Ca5(PO3)4Cl (ClA) and Ca5(PO3)4Br (BrA). Results of formation enthalpies show that FA is regarded as the most stable one in these apatites. The electronic structures including band structure, density of states and Mulliken analysis have been discussed. The predicted elastic moduli results indicate that the degree of elastic anisotropy is ordered as follows BrA > ClA > FA. By using the Clarke’s model and Cahill’s model, the thermal conductivities and the anisotropy in thermal conductivity have also been analyzed. Optic properties results indicate that the refractive indexes n for FA, ClA and BrA are 1.17, 1.19 and 1.21, respectively

  2. Electronic structure, elastic anisotropy, thermal conductivity and optical properties of calcium apatite Ca{sub 5}(PO{sub 4}){sub 3}X (X = F, Cl or Br)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Cheng-Xiu [Kunming University of Science and Technology, Kunming 650093 (China); Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu 610041 (China); Research Center of Multipurpose Utilization of Metal Mineral Resources of China Geological Survey, Chengdu 610041 (China); Duan, Yong-Hua, E-mail: duanyh@kmust.edu.cn [Kunming University of Science and Technology, Kunming 650093 (China); Hu, Wen-Cheng [School of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031 (China)

    2015-01-15

    Highlights: • The degree of elastic anisotropy is ordered as follows BrA > ClA > FA. • The thermal conductivity in (112{sup ¯}0) plane is smaller than in (0 0 0 1) plane. • The refractive indexes for FA, ClA and BrA are 1.17, 1.19 and 1.21, respectively. - Abstract: The density-functional theory with the generalized gradient approximation was performed to investigate the structural properties, phase stability, electronic structure, elastic properties, and optical properties of selected Ca{sub 5}(PO{sub 3}){sub 4}F (FA), Ca{sub 5}(PO{sub 3}){sub 4}Cl (ClA) and Ca{sub 5}(PO{sub 3}){sub 4}Br (BrA). Results of formation enthalpies show that FA is regarded as the most stable one in these apatites. The electronic structures including band structure, density of states and Mulliken analysis have been discussed. The predicted elastic moduli results indicate that the degree of elastic anisotropy is ordered as follows BrA > ClA > FA. By using the Clarke’s model and Cahill’s model, the thermal conductivities and the anisotropy in thermal conductivity have also been analyzed. Optic properties results indicate that the refractive indexes n for FA, ClA and BrA are 1.17, 1.19 and 1.21, respectively.

  3. Stability of Lead Immobilized by Apatite in Lead-Containing Rhizosphere Soil of Buckwheat (Fagopyrum esculentum) and Hairy Vetch (Vicia villosa).

    Science.gov (United States)

    Katoh, Masahiko; Matsuoka, Hideaki; Sato, Takeshi

    2015-01-01

    This study conducted plant growth experiments using a rhizobox system to understand the growth of buckwheat and hairy vetch as well as the stability of lead immobilized by hydroxyapatite (HAP) in the lead-containing rhizosphere soil. The shoot dry weight of buckwheat did not significantly differ between the lead-containing rhizosphere soil with and without HAP, whereas that of hairy vetch with rhizosphere soil without HAP was reduced. Lead was not accumulated from the rhizosphere soil to the shoots of either plant when HAP was added. The percentage of each lead fraction in sequential extraction was approximately the same through the 3 mm of rhizosphere soils from the root surface and non-planted soil, with and without the addition of HAP. For hairy vetch, the amount of water-soluble lead in the HAP-added rhizosphere soil within 3 mm thickness from the root surface did not increase. However, for buckwheat, the amount of water-soluble lead in the HAP-added rhizosphere soil 1 mm from the root surface increased to the same level as that in the non-planted soil without HAP. Our results suggest that when applying phytostabilization combined with apatite to lead-contaminated soil, the plant that cannot re-mobilize lead should be selected.

  4. Crystal Structures of Furazanes

    Directory of Open Access Journals (Sweden)

    Thomas M. Klapötke

    2015-09-01

    Full Text Available Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA and BAM (Bundesanstalt für Materialforschung und -prüfung methods. The standard enthalpies of formation were calculated for all compounds at the CBS-4M level of theory, and the energetic performance was predicted with the EXPLO5 V6.02 computer code.

  5. Liquid crystals fundamentals

    CERN Document Server

    Singh, Shri

    2001-01-01

    Liquid crystals are partially ordered systems without a rigid, long-range structure. The study of these materials covers a wide area: chemical structure, physical properties and technical applications. Due to their dual nature - anisotropic physical properties of solids and rheological behavior of liquids - and easy response to externally applied electric, magnetic, optical and surface fields liquid crystals are of greatest potential for scientific and technological applications. The subject has come of age and has achieved the status of being a very exciting interdisciplinary field of scienti

  6. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...... readers with a general interest in photonic crystals, as well as for scientists who are entering the field and desire a broad overview as well as a solid starting point for further specialized stuides. Teh book, therefore, covers bothe general aspects such as the link from classical optics to photonic...

  7. Cirrus Crystal Terminal Velocities.

    Science.gov (United States)

    Heymsfield, Andrew J.; Iaquinta, Jean

    2000-04-01

    Cirrus crystal terminal velocities are of primary importance in determining the rate of transport of condensate from upper- to middle-tropospheric levels and profoundly influence the earth's radiation balance through their effect on the rate of buildup or decay of cirrus clouds. In this study, laboratory and field-based cirrus crystal drag coefficient data, as well as analytical descriptions of cirrus crystal shapes, are used to derive more physically based expressions for the velocities of cirrus crystals than have been available in the past.Polycrystals-often bullet rosettes-are shown to be the dominant crystal types in synoptically generated cirrus, with columns present in varying but relatively large percentages, depending on the cloud. The two critical parameters needed to calculate terminal velocity are the drag coefficient and the ratio of mass to cross-sectional area normal to their fall direction. Using measurements and calculations, it is shown that drag coefficients from theory and laboratory studies are applicable to crystals of the types found in cirrus. The ratio of the mass to area, which is shown to be relatively independent of the number of bullets in the rosette, is derived from an analytic model that represents bullet rosettes containing one to eight bullets in 19 primary geometric configurations. The ratio is also derived for columns. Using this information, a general set of equations is developed to calculate the terminal velocities and masses in terms of the aspect ratio (width divided by length), ice density, and rosette maximum dimension. Simple expressions for terminal velocity and mass as a function of bullet rosette maximum dimension are developed by incorporating new information on bullet aspect ratios.The general terminal velocity and mass relations are then applied to a case from the First International Satellite Cloud Climatology Project (ISCCP) Research Experiment (FIRE) 2, when size spectra from a balloon-borne ice crystal

  8. Scheelite and coexisting F-rich zoned garnet, vesuvianite, fluorite, and apatite in calc-silicate rocks from the Mogok metamorphic belt, Myanmar: Implications for metasomatism in marble and the role of halogens in W mobilization and mineralization

    Science.gov (United States)

    Guo, Shun; Chen, Yi; Liu, Chuan-Zhou; Wang, Jian-Gang; Su, Bin; Gao, Yi-Jie; Wu, Fu-Yuan; Sein, Kyaing; Yang, Yue-Heng; Mao, Qian

    2016-03-01

    to a significant enrichment of F (up to 1.2 wt.%) and OH (up to 0.32 for nOH) and a negative correlation between F and Si in the garnet. Detailed petrographic observations show that the occurrence of scheelite in the MMB calc-silicate rocks is always associated with the growth of F-rich minerals such as garnet rims (0.8-1.2 wt.% F), vesuvianite (2.4-2.6 wt.% F), fluorite (48-49 wt.% F), apatite (3.9-4.1 wt.% F), and titanite (2.6-3.4 wt.% F). These textural characteristics, combined with the positive correlation of whole-rock F and W (as well as Sn, Mo) contents in the calc-silicate rocks, indicate that the elevated F contents increased the solubility of W in the infiltrating fluid, thereby allowing the W transfer in the hydrothermal-metasomatic system. The mineralization of scheelite was triggered by the crystallization of F-rich minerals during the formation of the calc-silicate rocks, which caused F depletion and consequent saturation of W in the metasomatic fluid. Our results suggest that, in the MMB metasomatic system, F rather than Cl is the key fluxing compound that facilitates the transfer of W and the mineralization of scheelite.

  9. Electrospray crystallization for high-quality submicron-sized crystals

    NARCIS (Netherlands)

    Radacsi, N.; Stankiewicz, A.I.; Creyghton, Y.L.M.; Heijden, A.E.D.M. van der; Horst, J.H. ter

    2011-01-01

    Nano- and submicron-sized crystals are too small to contain inclusions and are, therefore, expected to have a higher internal quality compared to conventionally sized particles (several tens to hundreds of microns). Using electrospray crystallization, nano- and submicron-sized crystals can be easily

  10. Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    William J. Wadsworth; Jonathan C. Knight; William H. Reeves; Philip St.J. Russell

    2003-01-01

    By offering greatly enhanced control of light compared to conventional step-index structures, photonic crystal fibres are radically improving the performance of linear and nonlinear fibre devices, including gas-Raman cells, super-continuum generators, soliton systems and cladding-pumped lasers.

  11. Photonic Crystal VCSELs

    Institute of Scientific and Technical Information of China (English)

    D.; S.; Song; J.; W.; Paek; K.; H.; Lee; Y.; H.; Lee

    2003-01-01

    Photonic crystal vertical cavity surface emitting lasers (PC VCSELs) are reviewed. The PC VCSEL shows single-transverse-mode continuous wave operation in the entire current range with side mode suppression ratio 35-40 dB. A simple 3-D plane wave expansion method is found to be very effective in analyzing the modal properties of the PC VCSELs.

  12. Photonic Crystal VCSELs

    Institute of Scientific and Technical Information of China (English)

    D. S. Song; J. W. Paek; K. H. Lee; Y. H. Lee

    2003-01-01

    Photonic crystal vertical cavity surface emitting lasers (PC VCSELs) are reviewed. The PC VCSEL shows single-transverse-mode continuous wave operation in the entire current range with side mode suppression ratio 35-40dB. A simple 3-D plane wave expansion method is found to be very effective in analyzing the modal properties of the PC VCSELs.

  13. Liquid crystal display

    International Nuclear Information System (INIS)

    An improved liquid crystal display device is described which can display letters, numerals and other necessary patterns in the night time using a minimized amount of radioactive material. To achieve this a self-luminous light source is placed in a limited region corresponding to a specific display area. (U.K.)

  14. The Crystal Set

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2014-01-01

    In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought…

  15. Incommensurability in crystal structures

    International Nuclear Information System (INIS)

    Incommensurate or modulated crystal structures (TaS2, Srsub(1-p)Cr2Sesub(4-p), etc.) are examined and compared with superstructures (TaSe2, Basub(1-p)Cr2Sesub(4-p)). Observed and calculated structure factors are given for Eusub(1-p)Cr2Sesub(4-p). (C.F.)

  16. Liquid crystal colloids

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available This special issue of "Condensed Matter Physics" focuses on the most recent developments in the study of a fascinating soft matter system, representing colloidal particles in a liquid crystalline environment. Furthermore, some articles address pioneering steps in the discovery of liquid crystals going back to 1861 paper by Julius Planer.

  17. Protein Crystals of Raf Kinase

    Science.gov (United States)

    1995-01-01

    This image shows crystals of the protein raf kinase grown on Earth (photo a) and on USML-2 (photo b). The space-grown crystals are an order of magnitude larger. Principal Investigator: Dan Carter of New Century Pharmaceuticals

  18. Dichroism in Helicoidal Crystals.

    Science.gov (United States)

    Cui, Xiaoyan; Nichols, Shane M; Arteaga, Oriol; Freudenthal, John; Paula, Froilanny; Shtukenberg, Alexander G; Kahr, Bart

    2016-09-21

    Accounting for the interactions of light with heterogeneous, anisotropic, absorbing, optically active media is part of the characterization of complex, transparent materials. Stained biological structures in thin tissue sections share many of these features, but systematic optical analyses beyond the employ of the simple petrographic microscopes have not be established. Here, this accounting is made for polycrystalline, spherulitic bundles of twisted d-mannitol lamellae grown from melts containing light-absorbing molecules. It has long been known that a significant percentage of molecular crystals readily grow as helicoidal ribbons with mesoscale pitches, but a general appreciation of the commonality of these non-classical crystal forms has been lost. Helicoidal crystal twisting was typically assayed by analyzing refractivity modulation in the petrographic microscope. However, by growing twisted crystals from melts in the presence of dissolved, light-absorbing molecules, crystal twisting can be assayed by analyzing the dichroism, both linear and circular. The term "helicoidal dichroism" is used here to describe the optical consequences of anisotropic absorbers precessing around radii of twisted crystalline fibrils or lamellae. d-Mannitol twists in two polymorphic forms, α and δ. The two polymorphs, when grown from supercooled melts in the presence of a variety of histochemical stains and textile dyes, are strongly dichroic in linearly polarized white light. The bis-azo dye Chicago sky blue is modeled because it is most absorbing when parallel and perpendicular to the radial axes in the respective spherulitic polymorphs. Optical properties were measured using Mueller matrix imaging polarimetry and simulated by taking into account the microstructure of the lamellae. The optical analysis of the dyed, patterned polycrystals clarifies aspects of the mesostructure that can be difficult to extract from bundles of tightly packed fibrils. PMID:27617640

  19. Ultrafast photonic crystal optical switching

    Institute of Scientific and Technical Information of China (English)

    GONG Qi-huang; HU Xiao-yong

    2006-01-01

    Photonic crystal,a novel and artificial photonic material with periodic dielectric distribution,possesses photonic bandgap and can control the propagation states of photons.Photonic crystal has been considered to be a promising candidate for the future integrated photonic devices.The properties and the fabrication method of photonic crystal are expounded.The progresses of the study of ultrafast photonic crystal optical switching are discussed in detail.

  20. Bacterial Ice Crystal Controlling Proteins

    OpenAIRE

    Lorv, Janet S. H.; Rose, David R; Glick, Bernard R.

    2014-01-01

    Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. R...

  1. Intensified crystallization in complex media: heuristics for crystallization of platform chemicals

    NARCIS (Netherlands)

    Urbanus, J.; Roelands, C.P.M.; Verdoes, D.; Horst, J.H. ter

    2012-01-01

    This paper presents heuristics for the integration of fermentation with the appropriate crystallization based in-situ product recovery (ISPR) technique. Here techniques, such as co-crystallization (CC), evaporative crystallization (EC), template induced crystallization (TIC), cooling crystallization

  2. The Bowen-Fenner Debate Revisited: A Review of Basalt Crystal Fractionation and the Generation of Andesite

    Science.gov (United States)

    Conrey, R. M.

    2002-12-01

    increases in Al and Fe/Mg in cpx, consistent with crystallization from increasingly aluminous wet magma. Further plagioclase-dominated fractionation of HAB in arcs in most cases generates Fe-rich basalt or basaltic andesite, consistent with lack of significant magnetite in HAB and mafic Fe-rich HAB groundmass compositions. Differentiation of HAB (by AFC?) may include Al-rich tholeiitic andesite, but not typical calc-alkaline andesite. The latter is likely made by magma mixing, as suggested by ubiquitous mineralogic disequilibrium, low Al content, and P systematics. P behaves incompatibly in virtually all common, non-alkaline, mafic arc magma, and apatite crystallization does not commence soon enough in mafic arc magma to buffer P concentrations in common andesite. Typical basalt to andesite mass balance fractionation models ignore P and fail P mass balance.

  3. Small Business Innovations (Crystal Components)

    Science.gov (United States)

    1991-01-01

    Scientific Materials Corporation, Bozeman, MT developed the SciMax line of improved Nd:Yag crystals under an Small Business Innovation Research (SBIR) contract with Langley Research Center. They reduced the amount of water trapped in the crystals during growth to improve the optical quality and efficiency. Applications of the crystals include fiber optics, telecommunications, welding, drilling, eye surgery and medical instrumentation.

  4. Generation of Absolute Controlled Crystal Chirality by the Removal of Crystal Water from Achiral Crystal of Nucleobase Cytosine

    OpenAIRE

    Kawasaki, Tsuneomi; Hakoda, Yuko; Mineki, Hiroko; Suzuki, Kenta; Soai, Kenso

    2010-01-01

    The enantioselective formation of chiral crystal of achiral nucleobase cytosine was achieved mediated by the crystal direction selective dehydration of crystal water in the achiral crystal of cytosine monohydrate (P21/c). Heat transfer from the enantiotopic face of the single crystal of cytosine monohydrate afforded the enantiomorphous crystal of anhydrous cytosine.

  5. Liquid crystal orientation control in photonic liquid crystal fibers

    Science.gov (United States)

    Chychlowski, M. S.; Nowinowski-Kruszelnicki, E.; Woliński, T. R.

    2011-05-01

    Similarly to liquid crystal displays technology in photonic liquid crystal fibers (PLCFs) a molecular orientation control is a crucial issue that influences proper operation of PLCF-based devices. The paper presents two distinct configurations: planar and radial escaped orientation of the LC molecules inside capillaries as well as methods of their application to photonic liquid crystal fibers. Possibilities of LC orientation control influence both: attenuation and transmitting spectra of the PLCF The orienting method is based on creation of an additional orienting layer on the inner surface of the capillary or air hole of the photonic liquid crystal fiber. Aligning materials used in the experiment are commercially available polyimides SE1211 and SE130 which induce liquid crystal homeotropic and planar anchoring conditions. The orienting layer increase an order parameter of the liquid crystal improving propagation properties and stability of photonic liquid crystal fiber-based devices.

  6. The complex post-rift evolution of the South Atlantic margin, South Africa: new insights from joint inversion of apatite (U-Th)/He and fission track thermochronometry.

    Science.gov (United States)

    Wildman, Mark; Brown, Roderick; Persano, Cristina; Beucher, Romain; Stuart, Finlay

    2013-04-01

    The continental edge of southwestern Africa has long been seen as a type example of a high elevation passive margin, with its characteristic topography forming during or shortly after rifting (c. 130 Ma). Recent work along the South Atlantic passive margin has highlighted the importance of interactions between rift-tectonics, mantle flow and dynamic topography on controlling margin evolution, however, the temporal relationship between these processes is still poorly understood. There is now increasing evidence from satellite imagery, onshore field observations (e.g. Viola et al., 2012) and offshore sedimentary basin analysis (e.g. Hirsch et al., 2010) that suggests that these processes have resulted in a much more complex structural and thermal history along the margin than previously thought. A critical step towards developing a better understanding of the post-rift evolution of this margin is to quantify the surface response (i.e. uplift and erosion) to these major structural and thermal events. Apatite fission track analysis (AFTA) has been used world-wide as a powerful means of extracting quantitative constraints on the timing and rate of major episodes of onshore denudation. Previous AFTA studies in SW Africa have identified two distinct cooling events occurred during early and late Cretaceous, respectively. However, in places AFT ages vary significantly over relatively short distances and this has been interpreted to indicate local differential erosion levels controlled by tectonic displacements related to fault reactivation. A limitation of the AFT system is that it is sensitive to a temperature range of c. 120-60°C and therefore is unable to evaluate the magnitude of denudation episodes where the amounts are less than c. 1.5-2 km. So while the Cretaceous history of erosion is well established from existing AFTA data, the details of the timing and amount of erosion occurring during the Cenozoic remain relatively poorly constrained. The apatite (U

  7. Apatite fission-track evidence for regional exhumation in the subtropical Eocene, block faulting, and localized fluid flow in east-central Alaska

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Bacon, Charles R.; O'Sullivan, Paul B.; Day, Warren C.

    2016-01-01

    The origin and antiquity of the subdued topography of the Yukon–Tanana Upland (YTU), the physiographic province between the Denali and Tintina faults, are unresolved questions in the geologic history of interior Alaska and adjacent Yukon. We present apatite fission-track (AFT) results for 33 samples from the 2300 km2 western Fortymile district in the YTU in Alaska and propose an exhumation model that is consistent with preservation of volcanic rocks in valleys that requires base level stability of several drainages since latest Cretaceous–Paleocene time. AFT thermochronology indicates widespread cooling below ∼110 °C at ∼56–47 Ma (early Eocene) and ∼44–36 Ma (middle Eocene). Samples with ∼33–27, ∼19, and ∼10 Ma AFT ages, obtained near a major northeast-trending fault zone, apparently reflect hydrothermal fluid flow. Uplift and erosion following ∼107 Ma magmatism exposed plutonic rocks to different extents in various crustal blocks by latest Cretaceous time. We interpret the Eocene AFT ages to suggest that higher elevations were eroded during the Paleogene subtropical climate of the subarctic, while base level remained essentially stable. Tertiary basins outboard of the YTU contain sediment that may account for the required >2 km of removed overburden that was not carried to the sea by the ancestral Yukon River system. We consider a climate driven explanation for the Eocene AFT ages to be most consistent with geologic constraints in concert with block faulting related to translation on the Denali and Tintina faults resulting from oblique subduction along the southern margin of Alaska.

  8. Biological apatite (BAp) crystallographic orientation and texture as a new index for assessing the microstructure and function of bone regenerated by tissue engineering.

    Science.gov (United States)

    Nakano, Takayoshi; Kaibara, Kazuhiro; Ishimoto, Takuya; Tabata, Yasuhiko; Umakoshi, Yukichi

    2012-10-01

    Recently, there have been remarkable advances in medical techniques for regenerating bone defects. To determine the degree of bone regeneration, it is essential to develop a new method that can analyze microstructure and related mechanical function. Here, quantitative analysis of the orientation distribution of biological apatite (BAp) crystallites by a microbeam X-ray diffractometer system is proposed as a new index of bone quality for the evaluation of regenerated bone microstructure. Preferential alignment of the BAp c-axis in the rabbit ulna and skull bone, regenerated by controlled release of basic fibroblast growth factor (bFGF) was investigated. The BAp c-axis orientation was evaluated by the relative intensity between the (002) and (310) diffraction peaks, or the three-dimensional texture for the (002) peak. It was found that new bone in the defects was initially produced without preferential alignment of the BAp c-axis, and subsequently reproduced to recover towards the original alignment. In other words, the BAp density recovered prior to the BAp orientation. Perfect recovery of BAp alignment was not achieved in the ulna and skull defects after 4 weeks and 12 weeks, respectively. Apparent recovery of the macroscopic shape and bio-mineralization of BAp was almost complete in the ulna defect after 4 weeks. However, an additional 2 weeks was required for complete repair of BAp orientation. It is finally concluded that orientation distribution of BAp crystallites offers an effective means of evaluating the degree of microstructural regeneration, and also the related mechanical function, in regenerated hard tissues.

  9. Mesozoic exhumation history and palaeolandscape of the Iberian Massif in eastern Galicia from apatite fission-track and (U+Th)/He data

    Science.gov (United States)

    Grobe, R. W.; Alvarez-Marrón, J.; Glasmacher, U. A.; Stuart, F. M.

    2014-03-01

    Apatite fission-track (AFT) and (U+Th)/He (AHe) data, combined with time-temperature inverse modelling, reveal the cooling and exhumation history of the Iberian Massif in eastern Galicia since the Mesozoic. The continuous cooling at various rates correlates with variation of tectonic boundary conditions in the adjacent continental margins. The data provide constraints on the 107 timescale longevity of a relict paleolandscape. AFT ages range from 68 to 174 Ma with mean track lengths of 10.7 ± 2.6 to 12.6 ± 1.8 μm, and AHe ages range from 73 to 147 Ma. Fastest exhumation (≈0.25 km/Ma) occurred during the Late Jurassic to Early Cretaceous main episode of rifting in the adjacent western and northern margins. Exhumation rates have decreased since then and have been approximately one order of magnitude lower. Across inland Galicia, the AFT data are consistent with Early Cretaceous movement on post-Variscan NE trending faults. This is coeval with an extensional episode offshore. The AHe data in this region indicate less than 1.7 km of denudation in the last 100 Ma. This low exhumation suggests the attainment of a mature landscape during Late Cretaceous post-rift tectonic stability, whose remains are still preserved. The low and steady rate of denudation prevailed across inland Galicia despite minor N-S shortening in the northern margin since ≈45 Ma ago. In north Galicia, rock uplift in response to NW strike-slip faulting since Early Oligocene to Early Miocene has caused insufficient exhumation (<3 km) to remove the Mesozoic cooling signal recorded by the AFT data.

  10. Re-evaluating origins of Paleozoic orbital-scale and My-scale stratigraphic cyclicity using oxygen isotopes of marine apatite

    Science.gov (United States)

    Elrick, M.; Theiling, B. P.; Wallace, Z. A.; Reardon, D.; Labor, W.; Martin, J.

    2012-12-01

    High-frequency (104-105 yr) sedimentary cycles and My-scale depositional sequences in Paleozoic marine strata have been studied for over a century and though debated, their origins are most commonly attributed to sea-level changes. Early studies focused mainly on repetitive shallowing and deepening facies changes, subaerial exposure features, and widespread correlations to argue for eustatic drivers. Subsequent studies utilized 1D and 2D computer models and statistical and time series analysis to argue for eustasy and for Milankovitch-scale periodicities. With increasing high-resolution numeric age control provided by newly discovered ash beds, the durations of many Paleozoic cycles and sequences are found to lie within the Milankovitch-frequency band. Recently the origins of Paleozoic cycles and sequences have been evaluated using oxygen isotopes from marine apatite (conodonts) to specifically test for glacio-eustatic origins. Isotopic trends from well studied Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian marine successions support the hypothesis that the cycles and sequences were generated by glacio-eustasy with decreasing and low isotopic values occurring within deepening and deepest water facies and increasing and high values occurring in shallowing and shallowest water facies. Of particular interest is that the magnitudes of isotopic change and by inference, the magnitude of climatic change, observed across cycles and sequences developed in Paleozoic greenhouse time intervals (Silurian, Devonian) are as large as those observed in icehouse (Neogene, Pennsylvanian) and transitional (Late Ordovician, Early Mississippian) climatic intervals. These oxygen isotope results combined with earlier stratigraphic, modeling, and statistical studies suggest that short- and long-period Milankovitch-forced glacio-eustasy controlled cycle and sequence development throughout the Paleozoic.

  11. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    , leading to reduced mode confinement and dispersion flexibility. In this thesis, we treat the nonlinear photonic crystal fiber – a special sub-class of photonic crystal fibers, the core of which has a diameter comparable to the wavelength of the light guided in the fiber. The small core results in a large...... nonlinear coefficient and in various applications, it is therefore possible to reduce the required fiber lengths quite dramatically, leading to increased stability and efficiency. Furthermore, it is possible to design these fibers with zero-dispersion at previously unreachable wavelengths, paving the way...... for completely new applications, especially in and near the visible wavelength region. One such application is supercontinuum generation. Supercontinuum generation is extreme broadening of pulses in a nonlinear medium (in this case a small-core fiber), and depending on the dispersion of the fiber, it is possible...

  12. Crystalizing the genetic code

    CERN Document Server

    Frappat, L; Sorba, Paul

    2000-01-01

    New developments are presented in the framework of the model introduced by the authors in refs. [1,2] and in which nucleotides as well as codons are classified in crystal bases of the quantum group U_q(sl(2)+sl(2)) in the limit q -> 0. An operator which gives the correspondence between the amino-acids and the codons is now obtained for any known genetic code. The free energy released by base pairing of dinucleotides as well as the relative hydrophilicity and hydrophobicity of the dinucleosides are also computed. For the vertebrate series, a universal behaviour in the ratios of codon usage frequencies is put in evidence and is shown to fit nicely in our model. Then a first attempt to represent the mutations relative to the deletion of a pyrimidine by action of a suitable crystal spinor operator is proposed. Finally recent theoretical descriptions are reviewed and compared with our model.

  13. Liquid Crystal Motion Picture Projector①

    Institute of Scientific and Technical Information of China (English)

    SHIYongji

    1997-01-01

    A liquid crystal moving picture projector and method are described.Light incident on a liquid crystal display-type device is selectively scattered or transmitted by respective portions of liquid crystal display,and a projection mechanism projects an image formed by either such scattered light or such transmitted light.A liquid cystal moving picture projector includes a liquid crystal display for creating characteristics of an image,and projecttion optics for projecting images sequentially created by the display.The display includes a liquid crystal material capable of temporary storing information at respective areas.The temporary storage may be a function of charge storing directly on liquid crystal material.A method of projecting plural images in sequence includes:creating an image or characteristics of an image in a liquid crystal material,storing such image in such liquid crystal material,directing light at such liquid crystal material,projecting such image as a function of light transmitted through or scattered by such liquid crystal material,and creating a further image in such liquid crystal material for subsequent projection.

  14. Sonic Crystal Noise Barriers

    OpenAIRE

    Chong, Yung

    2012-01-01

    An alternative road traffic noise barrier using an array of periodically arranged vertical cylinders known as a Sonic Crystal (SC) is investigated. As a result of multiple (Bragg) scattering, SCs exhibit a selective sound attenuation in frequency bands called band gaps or stop bands related to the spacing and size of the cylinders. Theoretical studies using Plane Wave Expansion (PWE), Multiple Scattering Theory (MST) and Finite Element Method (FEM) have enabled study of the performance of SC ...

  15. Photonic crystal optical memory

    Science.gov (United States)

    Lima, A. Wirth; Sombra, A. S. B.

    2011-06-01

    After several decades pushing the technology and the development of the world, the electronics is giving space for technologies that use light. We propose and analyze an optical memory embedded in a nonlinear photonic crystal (PhC), whose system of writing and reading data is controlled by an external command signal. This optical memory is based on optical directional couplers connected to a shared optical ring. Such a device can work over the C-Band of ITU (International Telecommunication Union).

  16. Textures of liquid crystals

    CERN Document Server

    Dierking, Ingo

    2006-01-01

    A unique compendium of knowledge on all aspects of the texture of liquid crystals, providing not just detailed information on texture formation and determination, but also an in-depth discussion of different characterization methods. Experts as well as graduates entering the field will find all the information they need in this handbook, while the magnitude of the color images make it valuable hands-on-reference.

  17. Crystals against cancer

    CERN Multimedia

    2009-01-01

    This is a remarkable example of direct technology transfer from particle physics to medicine. Clinical trials have begun in Portugal on a new medical imaging system for the diagnosis of breast cancer, which uses positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

  18. Hydrophobic photonic crystal fibers.

    Science.gov (United States)

    Xiao, Limin; Birks, T A; Loh, W H

    2011-12-01

    We propose and demonstrate hydrophobic photonic crystal fibers (PCFs). A chemical surface treatment for making PCFs hydrophobic is introduced. This repels water from the holes of PCFs, so that their optical properties remain unchanged even when they are immersed in water. The combination of a hollow core and a water-repellent inner surface of the hydrophobic PCF provides an ultracompact dissolved-gas sensor element, which is demonstrated for the sensing of dissolved ammonia gas. PMID:22139276

  19. Variable frequency photonic crystals

    CERN Document Server

    Wu, Xiang-Yao; Liu, Xiao-Jing; Yang, Jing-Hai; Li, Hong; Chen, Wan-Jin

    2015-01-01

    In this paper, we have firstly proposed a new one-dimensional variable frequency photonic crystals (VFPCs), and calculated the transmissivity and the electronic field distribution of VFPCs with and without defect layer, and considered the effect of defect layer and variable frequency function on the transmissivity and the electronic field distribution. We have obtained some new characteristics for the VFPCs, which should be help to design a new type optical devices.

  20. Nematic liquid crystal bridges

    Science.gov (United States)

    Doss, Susannah; Ellis, Perry; Vallamkondu, Jayalakshmi; Danemiller, Edward; Vernon, Mark; Fernandez-Nieves, Alberto

    We study the effects of confining a nematic liquid crystal between two parallel glass plates with homeotropic boundary conditions for the director at all bounding surfaces. We find that the free surface of the nematic bridge is a surface of constant mean curvature. In addition, by changing the distance between the plates and the contact angle with the glass plates, we transition between loops and hedgehogs that can be either radial or hyperbolic.

  1. Modern trends in technical crystallization

    Science.gov (United States)

    Matz, G.

    1980-04-01

    Interesting and significant developments have occurred in the last decade in both crystallization equipment and in the theory of crystallization process. In the field of technical crystallization new crystallizers have been developed and computer modelling has become important in scaling up and in the achievement of increased performance. The DP-Kristaller developed by Escher-Wyss-Tsukishima, the Brodie purifier, the sieve tray column having dancing balls, the automated multiple crystallization process due to Mützenberg and Saxer and the double belt cooler, all of which represent technical developments, are described in the first section. The second part of the paper reviews computer modelling of the fluidized bed crystallizer, chemical precipitation, flaking and prilling. Finally, there is a brief discussion of the impact of technical crystallization processes on environmental protection.

  2. Phononic crystals fundamentals and applications

    CERN Document Server

    Adibi, Ali

    2016-01-01

    This book provides an in-depth analysis as well as an overview of phononic crystals. This book discusses numerous techniques for the analysis of phononic crystals and covers, among other material, sonic and ultrasonic structures, hypersonic planar structures and their characterization, and novel applications of phononic crystals. This is an ideal book for those working with micro and nanotechnology, MEMS (microelectromechanical systems), and acoustic devices. This book also: Presents an introduction to the fundamentals and properties of phononic crystals Covers simulation techniques for the analysis of phononic crystals Discusses sonic and ultrasonic, hypersonic and planar, and three-dimensional phononic crystal structures Illustrates how phononic crystal structures are being deployed in communication systems and sensing systems.

  3. Crystallization of undercooled liquid fenofibrate.

    Science.gov (United States)

    Amstad, Esther; Spaepen, Frans; Weitz, David A

    2015-11-28

    Formulation of hydrophobic drugs as amorphous materials is highly advantageous as this increases their solubility in water and therefore their bioavailability. However, many drugs have a high propensity to crystallize during production and storage, limiting the usefulness of amorphous drugs. We study the crystallization of undercooled liquid fenofibrate, a model hydrophobic drug. Nucleation is the rate-limiting step; once seeded with a fenofibrate crystal, the crystal rapidly grows by consuming the undercooled liquid fenofibrate. Crystal growth is limited by the incorporation of molecules into its surface. As nucleation and growth both entail incorporation of molecules into the surface, this process likely also limits the formation of nuclei and thus the crystallization of undercooled liquid fenofibrate, contributing to the good stability of undercooled liquid fenofibrate against crystallization.

  4. Living liquid crystals.

    Science.gov (United States)

    Zhou, Shuang; Sokolov, Andrey; Lavrentovich, Oleg D; Aranson, Igor S

    2014-01-28

    Collective motion of self-propelled organisms or synthetic particles, often termed "active fluid," has attracted enormous attention in the broad scientific community because of its fundamentally nonequilibrium nature. Energy input and interactions among the moving units and the medium lead to complex dynamics. Here, we introduce a class of active matter--living liquid crystals (LLCs)--that combines living swimming bacteria with a lyotropic liquid crystal. The physical properties of LLCs can be controlled by the amount of oxygen available to bacteria, by concentration of ingredients, or by temperature. Our studies reveal a wealth of intriguing dynamic phenomena, caused by the coupling between the activity-triggered flow and long-range orientational order of the medium. Among these are (i) nonlinear trajectories of bacterial motion guided by nonuniform director, (ii) local melting of the liquid crystal caused by the bacteria-produced shear flows, (iii) activity-triggered transition from a nonflowing uniform state into a flowing one-dimensional periodic pattern and its evolution into a turbulent array of topological defects, and (iv) birefringence-enabled visualization of microflow generated by the nanometers-thick bacterial flagella. Unlike their isotropic counterpart, the LLCs show collective dynamic effects at very low volume fraction of bacteria, on the order of 0.2%. Our work suggests an unorthodox design concept to control and manipulate the dynamic behavior of soft active matter and opens the door for potential biosensing and biomedical applications. PMID:24474746

  5. Slotted Photonic Crystal Sensors

    Directory of Open Access Journals (Sweden)

    Andrea Di Falco

    2013-03-01

    Full Text Available Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.

  6. Quartz Crystal Microbalance Data

    Energy Technology Data Exchange (ETDEWEB)

    Baxamusa, S H

    2011-11-16

    We are using a Qpod quartz crystal microbalance (manufactured by Inficon) for use as a low-volume non-volatile residue analysis tool. Inficon has agreed to help troubleshoot some of our measurements and are requesting to view some sample data, which are attached. The basic principle of an NVR analysis is to evaporate a known volume of solvent, and weigh the remaining residue to determine the purity of the solvent. A typical NVR analysis uses 60 g of solvent and can measure residue with an accuracy of +/- 0.01 mg. The detection limit is thus (0.01 mg)/(60 g) = 0.17 ppm. We are attempting to use a quartz crystal microbalance (QCM) to make a similar measurement. The attached data show the response of the QCM as a 5-20 mg drop of solvent evaporates on its surface. The change in mass registered by the QCM after the drop evaporates is the residue that deposits on the crystal. On some measurements, the change in mass in less than zero, which is aphysical since the drop will leave behind {>=}0 mass of residue. The vendor, Inficon, has agreed to look at these data as a means to help troubleshoot the cause.

  7. Functionalizing Designer DNA Crystals

    Science.gov (United States)

    Chandrasekaran, Arun Richard

    Three-dimensional crystals have been self-assembled from a DNA tensegrity triangle via sticky end interaction. The tensegrity triangle is a rigid DNA motif containing three double helical edges connected pair-wise by three four-arm junctions. The symmetric triangle contains 3 unique strands combined in a 3:3:1 ratio: 3 crossover, 3 helical and 1 central. The length of the sticky end reported previously was two nucleotides (nt) (GA:TC) and the motif with 2-helical turns of DNA per edge diffracted to 4.9 A at beam line NSLS-X25 and to 4 A at beam line ID19 at APS. The purpose of these self-assembled DNA crystals is that they can be used as a framework for hosting external guests for use in crystallographic structure solving or the periodic positioning of molecules for nanoelectronics. This thesis describes strategies to improve the resolution and to incorporate guests into the 3D lattice. The first chapter describes the effect of varying sticky end lengths and the influence of 5'-phosphate addition on crystal formation and resolution. X-ray diffraction data from beam line NSLS-X25 revealed that the crystal resolution for 1-nt (G:C) sticky end was 3.4 A. Motifs with every possible combination of 1-nt and 2-nt sticky-ended phosphorylated strands were crystallized and X-ray data were collected. The position of the 5'-phosphate on either the crossover (strand 1), helical (strand 2), or central strand (3) had an impact on the resolution of the self-assembled crystals with the 1-nt 1P-2-3 system diffracting to 2.62 A at APS and 3.1 A at NSLS-X25. The second chapter describes the sequence-specific recognition of DNA motifs with triplex-forming oligonucleotides (TFOs). This study examined the feasibility of using TFOs to bind to specific locations within a 3-turn DNA tensegrity triangle motif. The TFO 5'-TTCTTTCTTCTCT was used to target the tensegrity motif containing an appropriately embedded oligopurine.oligopyrimidine binding site. As triplex formation involving cytidine

  8. Instabilities in liquid crystals

    CERN Document Server

    Barclay, G J

    1998-01-01

    and we examine the differences which occur for differing dielectric anisotropies. Finally, in Chapter 7 we study how a sample of smectic C liquid crystal behaves when it is subjected to a uniform shear flow within the smectic plane. We find travelling wave solutions for the behaviour of the c-director and adapt these solutions to incorporate the effects of an applied field. This thesis contains theoretical work dealing with the effects of magnetic and electric fields on samples of nematic, smectic A and smectic C liquid crystals. Some background material along with the continuum theory is introduced in Chapter 2. In Chapter 3 we consider the effect on the director within an infinite sample of nematic liquid crystal which is subjected to crossed electric and magnetic fields. In particular we examine the stability of the travelling waves which describe the director motion by considering the behaviour of the stable perturbations as time increases. The work of Chapter 4 examines a bounded sample of smectic A liqu...

  9. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting. PMID:26993991

  10. The fluid phenomena in the crystallization of the protein crystal

    Institute of Scientific and Technical Information of China (English)

    Duan Li; Kang Qi

    2008-01-01

    This paper reports that an optical diagnostic system consisting of Maeh-Zehnder interferometer with a phase shift device and image processor has been used for study of the kinetics of protein crystal growing process. The crystallization process of protein crystal by vapour diffusion is investigated. The interference fringes are observed in real time. The present experiment demonstrates that the diffusion and the sedimentation influence the crystallization of protein crystal which grows in solution, and the concentration capillary convection associated with surface tension occurs at the vicinity of free surface of the protein mother liquor, and directly affects on the outcome of protein crystallization. So far the detailed analysis and the important role of the fluid phenomena in protein crystallization have been discussed a little in both space- and ground-based crystal growth experiments. It is also found that these fluid phenomena affect theoutcome of protein crystallization, regular growth, and crystal quality. This may explain the fact that many results of space-based investigation do not show overall improvement.

  11. Discrete breathers in crystals

    Science.gov (United States)

    Dmitriev, S. V.; Korznikova, E. A.; Baimova, Yu A.; Velarde, M. G.

    2016-05-01

    It is well known that periodic discrete defect-containing systems, in addition to traveling waves, support vibrational defect-localized modes. It turned out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Since the nodes of the system are all on equal footing, it is only through the special choice of initial conditions that a group of nodes can be found on which such a mode, called a discrete breather (DB), will be excited. The DB frequency must be outside the frequency range of the small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically conserve its vibrational energy forever provided no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery in them of DBs was only a matter of time. It is well known that periodic discrete defect-containing systems support both traveling waves and vibrational defect-localized modes. It turns out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Because the nodes of the system are all on equal footing, only a special choice of the initial conditions allows selecting a group of nodes on which such a mode, called a discrete breather (DB), can be excited. The DB frequency must be outside the frequency range of small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically preserve its vibrational energy forever if no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery of DBs in them was only a matter of time. Experimental studies of DBs encounter major technical difficulties, leaving atomistic computer simulations as the primary investigation tool. Despite

  12. Functionalizing Designer DNA Crystals

    Science.gov (United States)

    Chandrasekaran, Arun Richard

    Three-dimensional crystals have been self-assembled from a DNA tensegrity triangle via sticky end interaction. The tensegrity triangle is a rigid DNA motif containing three double helical edges connected pair-wise by three four-arm junctions. The symmetric triangle contains 3 unique strands combined in a 3:3:1 ratio: 3 crossover, 3 helical and 1 central. The length of the sticky end reported previously was two nucleotides (nt) (GA:TC) and the motif with 2-helical turns of DNA per edge diffracted to 4.9 A at beam line NSLS-X25 and to 4 A at beam line ID19 at APS. The purpose of these self-assembled DNA crystals is that they can be used as a framework for hosting external guests for use in crystallographic structure solving or the periodic positioning of molecules for nanoelectronics. This thesis describes strategies to improve the resolution and to incorporate guests into the 3D lattice. The first chapter describes the effect of varying sticky end lengths and the influence of 5'-phosphate addition on crystal formation and resolution. X-ray diffraction data from beam line NSLS-X25 revealed that the crystal resolution for 1-nt (G:C) sticky end was 3.4 A. Motifs with every possible combination of 1-nt and 2-nt sticky-ended phosphorylated strands were crystallized and X-ray data were collected. The position of the 5'-phosphate on either the crossover (strand 1), helical (strand 2), or central strand (3) had an impact on the resolution of the self-assembled crystals with the 1-nt 1P-2-3 system diffracting to 2.62 A at APS and 3.1 A at NSLS-X25. The second chapter describes the sequence-specific recognition of DNA motifs with triplex-forming oligonucleotides (TFOs). This study examined the feasibility of using TFOs to bind to specific locations within a 3-turn DNA tensegrity triangle motif. The TFO 5'-TTCTTTCTTCTCT was used to target the tensegrity motif containing an appropriately embedded oligopurine.oligopyrimidine binding site. As triplex formation involving cytidine

  13. Unifying the crystallization behavior of hexagonal and square crystals with the phase-field-crystal model

    Science.gov (United States)

    Tao, Yang; Zheng, Chen; Jing, Zhang; Yongxin, Wang; Yanli, Lu

    2016-03-01

    By employing the phase-field-crystal models, the atomic crystallization process of hexagonal and square crystals is investigated with the emphasis on the growth mechanism and morphological change. A unified regime describing the crystallization behavior of both