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Sample records for hydroxyl apatite cha

  1. The evaluation of hydroxyl ions as a nucleating agent for apatite on electrospun non-woven poly( ϵ -caprolactone) fabric.

    Science.gov (United States)

    Kim, Hyung-Sup; Um, Seung-Hoon; Rhee, Sang-Hoon

    2012-01-01

    The capacity of hydroxyl ions when used as a nucleating agent to form apatite in simulated body fluid (SBF) was investigated. A 25 wt% poly(ϵ-caprolactone) solution was prepared using 1,1,3,3-hexafluoro-2-propanol as a solvent and was electrospun under an electric field of 1 kV/cm. Subsequently, non-woven poly(ϵ-caprolactone) fabrics were dipped into 4 M NaOH solution and the experimental group was then directly air-dried (NaOH coated), while the control group was washed with deionized water and air-dried (NaOH treated) under ambient conditions. The non-woven poly(ϵ-caprolactone) fabrics that were coated and treated with NaOH were exposed to SBF for 1 week, which resulted in the deposition of a layer of apatite crystals on the non-woven poly(ϵ-caprolactone) fabric coated with NaOH only. On the other hand, when the non-woven poly(ϵ-caprolactone) fabrics were dipped into 0.05, 0.1, 1 and 4 M NaOH solutions, respectively, air-dried, and then soaked in SBF, the apatite forming capacity was gradually increased according to the concentration of NaOH solution. These results were explained in terms of the degree of apatite supersaturation in SBF induced by the release of hydroxyl ions from the coated NaOH because hydroxyl ions are one of the constituent elements of apatite. These results suggest that hydroxyl ions have a good potential for use as a nucleating agent for apatite on a previously non-bioactive polymer surface.

  2. 1, 6-diisocyanatohexane-extended poly (1, 4-butylene succinate / hydroxyl apatite nano particle scaffolds: Potential materials for bone regeneration applications

    Science.gov (United States)

    Kaur, Kulwinder; Singh, K. J.; Anand, Vikas; Bhatia, Gaurav; Nim, Lovedeep; Kaur, Manpreet; Arora, Daljit Singh

    2017-05-01

    Bioresorbable and bioactive scaffolds are promising materials for various biomedical applications including bone regeneration and drug delievrery. Authors present bioactive scaffolds prepared from 1, 6-diisocyanatohexane-extended poly (1, 4-butylene succinate) (PBSu-DCH) with different amount of hydroxyl apatite nanoparticles (nHAp) by solvent casting and particulate leaching techniques. Different weight ratios of nHAp (i.e. 0, 5 and 10 wt %) with fixed weight ratio (i.e. 10 wt %) of PBSu-DCH polymer have been prepared. Scaffolds have been assessed for their morphology, bioactivity, degradation, drug release and biological properties including cytotoxicity, cell attachment using MG-63 cell line and antimicrobial activity. Effectual drug release has been measured by incorporating gentamycin as an antibiotic in the scaffolds. The study is aimed at developing new biodegradable scaffolds to be used in skull, jaw and tooth socket for preserving bone mass.

  3. Experimental Study into the Partitioning Behavior of Fluorine, Chlorine, Hydroxyl, and Sulfur (S2-) Between Apatite and a Synthetic Kreep Basalt Melt

    Science.gov (United States)

    Turner, Amber; Vander Kaaden, Kathleen; McCubbin, Francis; Danielson, Lisa R.

    2017-01-01

    The mineral apatite (Ca5 (PO4)3(F, Cl, OH)) is known for its ability to constrain the petrogenesis of the rock in which it is hosted and for its ubiquity throughout the Solar System, as it is found in lunar, martian, and terrestrial rocks alike (McCubbin et. al, 2015). The abundance of volatile elements, and for this particular study, the elevated abundance of sulfur (S2-) in high-Al basalt samples bearing apatite, could provide more insight for inquiries posed about the behavior of volatiles in lunar and martian magmatic systems (Boyce et. al, 2010). Oxygen fugacity will be an important parameter for these experiments, as the Moon, Mars, and Earth have different redox states (Herd, 2008). The objective of this experimental endeavor is to determine apatite-melt partition coefficients for the volatile elements (F-, Cl-, OH-, S2-) that make up the X-site (i.e., the typically monovalent anion site) in the mineral apatite in a lunar melt composition under lunar oxygen fugacity conditions approx.1-2 log units below the iron-wüstite buffer). All experiments will be conducted at NASA, Johnson Space Center in the High Pressure Experimental Petrology Laboratory. In order to conduct apatite-melt partition experiments with oxygen fugacity as an additional parameter, we will create a synthetic mix of the lunar KREEP basalt 15386, a sample retrieved during Apollo 15 that is believed to represent an indigenous volcanic melt derived from the lunar interior (Rhodes, J.M et. al, 2006). Other geochemically significant elements including C, Co, Ni, Mo, and rare earth elements will be included in the mix at trace abundances in order to assess their partitioning behavior without effecting the overall behavior of the system. The synthetic mix will then be loaded into a piston cylinder, an apparatus used to simulate high-pressure/high-temperature conditions of planetary interiors, and exposed to 0.5 GPa of pressure, the pressure observed in the upper mantle of the Moon, and heated to

  4. Restoran Cha Dao = Restaurant Cha Dao

    Index Scriptorium Estoniae

    2012-01-01

    Tallinnas Suur-Patarei 2 asuva Hiina restorani Cha Dao sisekujundusest. Restorani mööbel, v.a toolid, projekteeriti eritellimusena. Sisearhitekt Dmitri Pisarenko (DM3 OÜ), loetletud tema töid. Arhitekt Meeli Truu

  5. Kioo cha Lugha

    African Journals Online (AJOL)

    Historia ya Kiswahili Nchini Rwanda: Kielelezo cha Nafasi ya Utashi wa Kisiasa katika Ustawi wa Lugha ya Kiswahili · EMAIL FULL TEXT EMAIL FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Wallace Mlaga, 1-19 ...

  6. Human osteoblast behavior on as-synthesized SiO(4) and B-CO(3) co-substituted apatite.

    Science.gov (United States)

    Landi, Elena; Uggeri, Jacopo; Sprio, Simone; Tampieri, Anna; Guizzardi, Stefano

    2010-07-01

    The functional behavior of synthetic apatite, commonly used as fillers or scaffolds, depends on physical and chemical parameters, which vary in response to chemical substitutions and to thermal treatments. The effect of silicon co-substituting with carbonate ions in the apatite lattice on the properties of the as-synthesized powder and finally on human osteoblast in vitro behavior was investigated. Dose-response curves of Si-free and Si-substituted carbonated apatites (namely CHA and SiCHA-1 and SiCHA-2 with 0.88 and 0.55 wt % of Si, respectively) showed that SiCHA-1 had toxic effect, whereas CHA and SiCHA-2, at worst, hindered osteoblast proliferation, but no toxicity occurred. Subsequent experiments compared the effects of CHA and SiCHA-2 used at the doses of 0.3 and 1 mg/mL. After 7 days of treatment, both the powders stimulated cell proliferation and protein content and inhibited alkaline phosphatase activity. However, SiCHA-2 slightly stimulated osteoblast differentiation, as shown by higher calcium deposition, compared with CHA. The cell behaviors were linked to the peculiar powder characteristics. The as-synthesized powder represents the most critical system in terms of reactivity toward cells and can inform on the limits for positively exploiting the characteristics of SiCHA powders in making bone fillers or scaffolds, using no thermal treatments. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

  7. 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.

  8. [Need for the differentiation of apatite and carbonate apatite].

    Science.gov (United States)

    Brien, G; Berg, W; Schubert, G; Rebentisch, G; Schorch, P

    1988-10-01

    With extensive analytical and clinical examinations it is shown that the proof of carbonate in apatite may allow no additional reference of an infection with urea-splitting bacteria. With certain analytical methods the presence of carbonate is demonstrable in each urinary calculus apatite phase. Carbonate-bearing apatite indeed is accompanied frequently with struvite, but may be occur also without an infection. Therefore, in the future it should be renounced on the differentiation of apatite and carbonate apatite in routine analyses of urinary calculi.

  9. Electron Microprobe Analysis Techniques for Accurate Measurements of Apatite

    Science.gov (United States)

    Goldoff, B. A.; Webster, J. D.; Harlov, D. E.

    2010-12-01

    Apatite [Ca5(PO4)3(F, Cl, OH)] is a ubiquitous accessory mineral in igneous, metamorphic, and sedimentary rocks. The mineral contains halogens and hydroxyl ions, which can provide important constraints on fugacities of volatile components in fluids and other phases in igneous and metamorphic environments in which apatite has equilibrated. Accurate measurements of these components in apatite are therefore necessary. Analyzing apatite by electron microprobe (EMPA), which is a commonly used geochemical analytical technique, has often been found to be problematic and previous studies have identified sources of error. For example, Stormer et al. (1993) demonstrated that the orientation of an apatite grain relative to the incident electron beam could significantly affect the concentration results. In this study, a variety of alternative EMPA operating conditions for apatite analysis were investigated: a range of electron beam settings, count times, crystal grain orientations, and calibration standards were tested. Twenty synthetic anhydrous apatite samples that span the fluorapatite-chlorapatite solid solution series, and whose halogen concentrations were determined by wet chemistry, were analyzed. Accurate measurements of these samples were obtained with many EMPA techniques. One effective method includes setting a static electron beam to 10-15nA, 15kV, and 10 microns in diameter. Additionally, the apatite sample is oriented with the crystal’s c-axis parallel to the slide surface and the count times are moderate. Importantly, the F and Cl EMPA concentrations are in extremely good agreement with the wet-chemical data. We also present EMPA operating conditions and techniques that are problematic and should be avoided. J.C. Stormer, Jr. et al., Am. Mineral. 78 (1993) 641-648.

  10. Peculiarities of the electronic structure of calcium and strontium apatites

    Energy Technology Data Exchange (ETDEWEB)

    Shpak, A.P. [Institute of Metal Physics NAS of Ukraine, akad. Vernadskii Str. 36, Kiev 03142 (Ukraine); Karbovskii, V.L. [Institute of Metal Physics NAS of Ukraine, akad. Vernadskii Str. 36, Kiev 03142 (Ukraine)], E-mail: karb@imp.kiev.ua; Kurgan, N.A. [Institute of Metal Physics NAS of Ukraine, akad. Vernadskii Str. 36, Kiev 03142 (Ukraine)

    2007-05-15

    The comparison of the calculated data of the total density of electronic states for a crystal elementary cell (LMTO-calculation) and cluster-calculation XO{sub 4}{sup 3-} of a tetrahedron has shown practical concordance of the form and main features of curves that indicates the determining role of nanofragment structures XO{sub 4}{sup 3-} tetrahedron in formation of the main features of calcium apatites total density of states. It is confirmed, that the electronic structure of stochiometric apatites systems is low sensitive to anions type (which is located along c-axis of crystal), right up to its elimination, that practically can be revealed in lability of apatite's structure relative to its position. The symmetry of XO{sub 4}{sup 3-} anion oscillations in a crystal lattice of apatite is determined not only by the symmetry of its local environment but also appreciably by the nature of chemical bonds X-O inside anion. The greatest influence on tetrahedral sublattice in calcium apatite renders ion Cl{sup -}, and in strontium apatite ion OH{sup -}. The symmetry of tetrahedrons in strontium fluorapatite is higher comparing to hydroxy- and chlorapatite. The indirect interaction metal-metal is observed in metal sublattice. This interaction occurs mainly between atoms in Ca{sub (2)} positions with participation of oxygen hydroxyl group atoms. The channel of interaction Ca{sub (2)}-O{sub (3)}-Ca{sub (1)} through of oxygen atoms from PO{sub 4}{sup -} groups is observed thus less expressed. The interaction of ions Ca{sub (2)} with hydroxyl in hydroxyvanadate is much weaker, than in hydroxyapatite. It is shown, that in the formation of the L{sub {alpha}}-spectra form curve of calcium in calcium apatites the significant role is played by the nuclear effects and, as consequence, the participation of d-states of calcium in formation of bond is graded by their significant localization, most likely in an internal valley of effective potential.

  11. Dicty_cDB: CHA884 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHA884 (Link to dictyBase) - - - Contig-U16381-1 - (Link to Original site) CHA884F...CHA884F 147 - - - - - - Show CHA884 Library CH (Link to library) Clone ID CHA884 (Link to dictyBase) Atlas...RN708T7 Sea urchin radial nerve Lambda Zap cDNA library Heliocidaris erythrogramma cDNA 3', mRNA sequence...1 BM424783 |BM424783.1 IpSpn00680 Spleen cDNA library Ictalurus punctatus cDNA 5', mRNA sequence. 28

  12. BIOMINERALOGICAL INVESTIGATION OF APATITE PIEZOELECTRICITY

    Directory of Open Access Journals (Sweden)

    M. Pawlikowski

    2016-01-01

    Full Text Available Investigation of apatite piezoelectricity was conducted in order to assess piezoelectric properties of bone. In the first stage, mineralogical analysis of different apatite crystals, regarding their purity and fitness for the experiments was performed. After the crystals had been chosen, 0.8 mm-thick plates were cut, perpendicular and parallel to the crystallographic Z axis. The plates were then polished and dusted with gold. Electrodes were attached to the opposite surfaces of the plates with conductive glue. So prepared plates were hooked up to the EEG machine used for measuring electrical activity in the brain. The plates were then gently tapped to observe and register currents generated in them. Acquired data was processed by subtracting from the resulting graphs those generated by a hand movement, without tapping the plate. Results indicate that apatite plates have weak piezoelectric properties. Observed phenomenon may be translated to bone apatite, which would explain, at least partially, piezoelectric properties of bone. Acquired results suggest that there is a relation between the mechanical workload of bones (bone apatite and theirelectrical properties. Considering the massive internal surface of bones, they may be treated as a kind of internal “antenna” reacting not only to mechanical stimuli, but to changes in electromagnetic field as well. Observed phenomena no doubt significantly influence the biological processes occurring in bones and the whole human body.

  13. Dicty_cDB: CHA851 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHA851 (Link to dictyBase) - - - Contig-U16368-1 - (Link to Or...iginal site) CHA851F 614 - - - - - - Show CHA851 Library CH (Link to library) Clone ID CHA851 (Link to dicty...Base) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U16368-1 Original site URL http://dictycdb.b...TCCXXXXXXXXXX sequence update 2002.10.25 Translated Amino Acid sequence VRDARPPHNLCRGFGCPEGSHCEVLEKHPVCVRNHVPPHPPPPPQICGSVNCGPGYICT...nly*skttgttttllnlcraiism*srwn dlysstkqlyqy*ipmlpis--- Frame C: VRDARPPHNLCRGFGCPEGSHCEVLEKHPVCVRNHVPPHPPPPPQICGSVNCGPGYICT

  14. Dicty_cDB: CHA613 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available HD817Q) /CSM/CH/CHD8-A/CHD817Q.Seq.d/ 178 1e-44 CHD178 (CHD178Q) /CSM/CH/CHD1-D/CHD178Q.Seq.d/ 178 1e-44 CHB757 (CHB757...Q) /CSM/CH/CHB7-C/CHB757Q.Seq.d/ 178 1e-44 CHA613 (CHA613Q) /CSM/CH/CHA6-A/CHA613Q.Seq.d/ 178 1e-

  15. [The roots of Cha and Gambir].

    Science.gov (United States)

    Sugiyama, Shigeru

    2005-01-01

    replaced with "A". The official name for Ji-cha [Er Cha] in modern China is "Gaiji-cha", [Hal-Er Cha], which comes from the name of a variety of tea made by the Ai-Ni tribal subgroup of the ethnic Ha-Ni in Yunnan province. The [see character in text] character is pronounced "ni", which is a homophony of [character in text]. Based on these facts, "Ai-Ni" should be considered the same as "Hai-Ni". Because the ethnic groups in Yunnan province used primitive and tough tea leaves, which were eaten instead of being infused in water, the leaves were first fermented by being buried in the ground. Even today, people of these ethnic groups prefer fungus-fermented black tea with a particular flavor. In contrast, the ethnic Hans used and still use improved and softer young shoots of tea leaves to prepare mainly green tea. It has recently been discovered that Acapsia, as well as Gambir, has anti-oxidant properties, and that consumption over time is effective against many lifestyle-related adult diseases. It may be well worthwhile to cast fresh light upon ancient tea drinking customs.

  16. ChaMP Serendipitous Galaxy Cluster Survey

    Energy Technology Data Exchange (ETDEWEB)

    Barkhouse, Wayne A.; Green, P.J.; Vikhlinin, A.; Kim, D.-W.; Perley, D.; Cameron, R.; Silverman, J.; Mossman, A.; Burenin, R.; Jannuzi, B.T.; Kim, M.; Smith, M.G.; Smith,; Tananbaum, H.; Wilkes, B.J.; /Harvard-Smithsonian Ctr. Astrophys. /UC, Berkeley, Astron. Dept. /SLAC /Garching, Max Planck Inst., MPE /Moscow, Space Res. Inst. /NOAO, Tucson

    2006-04-03

    We present a survey of serendipitous extended X-ray sources and optical cluster candidates from the Chandra Multi-wavelength Project (ChaMP). Our main goal is to make an unbiased comparison of X-ray and optical cluster detection methods. In 130 archival Chandra pointings covering 13 square degrees, we use a wavelet decomposition technique to detect 55 extended sources, of which 6 are nearby single galaxies. Our X-ray cluster catalog reaches a typical flux limit of about {approx} 10{sup -14} erg s{sup -1} cm{sup -2}, with a median cluster core radius of 21''. For 56 of the 130 X-ray fields, we use the ChaMP's deep NOAO/4m MOSAIC g', r', and i' imaging to independently detect cluster candidates using a Voronoi tessellation and percolation (VTP) method. Red-sequence filtering decreases the galaxy fore/background contamination and provides photometric redshifts to z {approx} 0.7. From the overlapping 6.1 square degree X-ray/optical imaging, we find 115 optical clusters (of which 11% are in the X-ray catalog) and 28 X-ray clusters (of which 46% are in the optical VTP catalog). The median redshift of the 13 X-ray/optical clusters is 0.41, and their median X-ray luminosity (0.5-2 keV) is L{sub X} = (2.65 {+-} 0.19) x 10{sup 43} ergs s{sup -1}. The clusters in our sample that are only detected in our optical data are poorer on average ({approx} 4{sigma}) than the X-ray/optically matched clusters, which may partially explain the difference in the detection fractions.

  17. Dicty_cDB: CHA838 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 8 (CHA838Q) /CSM/CH/CHA8-B/CHA838Q.Seq.d/ 1096 0.0 SFF555 (SFF555Q) /CSM/SF/SFF5-C/SFF555Q.Seq.d/ 1094 0.0 CHE471 (CHE471...Q) /CSM/CH/CHE4-C/CHE471Q.Seq.d/ 920 0.0 SFF882 (SFF882Q) /CSM/SF/SFF8-D/SFF882Q.Seq.d/ 918 0.0

  18. Nucleosome structure of the yeast CHA1 promoter

    DEFF Research Database (Denmark)

    Moreira, José Manuel Alfonso; Holmberg, S

    1998-01-01

    conditions. Five yeast TBP mutants defective in different steps in activated transcription abolished CHA1 expression, but failed to affect induction-dependent chromatin rearrangement of the promoter region. Progressive truncations of the RNA polymerase II C-terminal domain caused a progressive reduction...... in CHA1 transcription, but no difference in chromatin remodeling. Analysis of swi1, swi3, snf5 and snf6, as well as gcn5, ada2 and ada3 mutants, suggested that neither the SWI/SNF complex nor the ADA/GCN5 complex is involved in efficient activation and/or remodeling of the CHA1 promoter. Interestingly...

  19. The effect of CHA-doped Sr addition to the mechanical strength of metakaolin dental implant geopolymer composite

    Science.gov (United States)

    Sunendar, Bambang; Fathina, Afiya; Harmaji, Andrie; Mardhian, Deby Fajar; Asri, Lia; Widodo, Haris Budi

    2017-09-01

    The prospective material for implant plate required sufficient mechanical properties to maintain fracture fixation and resist physiological stress until bone healing process finished. Various problem implant plate based on metal and polymer materials when used as fixation for bone defect case induced developmental of bioceramic for implant plate materials. Materials that now has been attract a lot of attention is carbonate apatite and strontium as doping which known to have good biocompability along with biointegrity and mechanical charateristics. Other materials that have been known to have good mechanical properties are metakaolin and use of chitosan as coupling agent. Metakaolin and carbonate apatite can be produced by sol-gel methode which simpler, economical and energy-saving procedure furthermore use of chitosan which is widely found in the nature of Indonesia can be used to encourage the utilization of natural resources. The aim fo this paper is to investigated effect of CHA-doped Sr 5 (%) mol addition to the mechanical strength of metakaolin dental implant geoploymer composite. In this paper metakaolin is used as geopolymerization precursors. The test results have shown that addition of filler of apatite carbonate doped 5% mol strontium can be said to increase the value of mechnical properties but high concentration of calcium in the nanocomposite also can complicate the equilibrium of the geopolymerization process and induce alkali aggregate reactivity (AAR). The sample group of nanocomposite of metakaolin and carbonate apatite-doped 5% mol strontium (2: 1% wt) with 2% chitosan as a coupling agent based on geopolymerization for implant plate application has the best mechanical properties among all sample groups but does not qualify as an implant plate on cortical bone but can be used for the application of the implant plate on the trabecular bone specifically and potentially as a bone initiator.

  20. Atomic substitutions in synthetic apatite; Insights from solid-state NMR spectroscopy

    Science.gov (United States)

    Vaughn, John S.

    Apatite, Ca5(PO4)3X (where X = F, Cl, or OH), is a unique mineral group capable of atomic substitutions for cations and anions of varied size and charge. Accommodation of differing substituents requires some kind of structural adaptation, e.g. new atomic positions, vacancies, or coupled substitutions. These structural adaptations often give rise to important physicochemical properties relevant to a range of scientific disciplines. Examples include volatile trapping during apatite crystallization, substitution for large radionuclides for long-term storage of nuclear fission waste, substitution for fluoride to improve acid resistivity in dental enamel composed dominantly of hydroxylapatite, and the development of novel biomaterials with enhanced biocompatibility. Despite the importance and ubiquity of atomic substitutions in apatite materials, many of the mechanisms by which these reactions occur are poorly understood. Presence of substituents at dilute concentration and occupancy of disordered atomic positions hinder detection by bulk characterization methods such as X-ray diffraction (XRD) and infrared (IR) spectroscopy. Solid-state nuclear magnetic resonance (NMR) spectroscopy is an isotope-specific structural characterization technique that does not require ordered atomic arrangements, and is therefore well suited to investigate atomic substitutions and structural adaptations in apatite. In the present work, solid-state NMR is utilized to investigate structural adaptations in three different types of apatite materials; a series of near-binary F, Cl apatite, carbonate-hydroxylapatite compositions prepared under various synthesis conditions, and a heat-treated hydroxylapatite enriched in 17O. The results indicate that hydroxyl groups in low-H, near binary F,Cl apatite facilitate solid-solution between F and Cl via column reversals, which result in average hexagonal symmetry despite very dilute OH concentration ( 2 mol percent). In addition, 19F NMR spectra indicate

  1. CHaMP metrics - Columbia Habitat Monitoring Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of CHaMP is to generate and implement a standard set of fish habitat monitoring (status and trend) methods in up to 26 watersheds across the Columbia River...

  2. Dicty_cDB: CHA362 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHA362 (Link to dictyBase) - - - Contig-U15579-1 | Contig-U156... library) Clone ID CHA362 (Link to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U155...79-1 | Contig-U15687-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/C...XACNAVDTCITNDLCFPRECNPRGNPPCLINPINCTSTDPCIFSYCENGVCI PTYICTPTPSVTPTVTPTVTPTVTPTVT...GNPPCLINPINCTSTDPCIFSYCENGVCI PTYICTPTPSVTPTVTPTVTPTVTPTVTPTVTPTVTPTPTTTPTPSPTTVP

  3. Transformation of LEV-type zeolite into less dense CHA-type zeolite

    OpenAIRE

    Goto, Ikuhiro; Itakura, Masaya; SHIBATA, SYOHEI; Honda, Koutaro; Ide, Yusuke; Sadakane, Masahiro; Sano, Tsuneji

    2012-01-01

    Hydrothermal conversion of LEV-type zeolite into CHA-type zeolite occurred in the absence of both an organic structure-directing agent and a seed crystal. The LEV-CHA transformation proceeds from a more dense zeolite (LEV) to a less dense one (CHA). When amorphous aluminosilicate hydrogels were used as starting materials, the CHA-type zeolite was not obtained under the present hydrothermal synthesis conditions. From the fact that the LEV-CHA transformation proceeded at lower alkalinity condit...

  4. Apatite glass-ceramics: a review

    Science.gov (United States)

    Duminis, Tomas; Shahid, Saroash; Hill, Robert Graham

    2016-12-01

    This article is a review of the published literature on apatite glass-ceramics (GCs). Topics covered include crystallization mechanisms of the various families of the apatite GCs and an update on research and development on apatite GCs for applications in orthopedics, dentistry, optoelectronics and nuclear waste management. Most apatite GCs crystallize through a homogenous nucleation and crystallization mechanism, which is aided by a prior liquid-liquid phase separation. Careful control of the base glass composition and heat-treatment conditions, which determine the nature and morphology of the crystal phases in the GC can produce GC materials with exceptional thermal, mechanical, optical and biological properties. The GCs reviewed for orthopedic applications exhibit suitable mechanical properties and can chemically bond to bone and stimulate its regeneration. The most commercially successful apatite GCs are those developed for dental veneering. These materials exhibit excellent translucency and clinical esthetics, and mimic the natural tooth mineral. Due to the ease of solid solution of the apatite lattice, rare earth doped apatite GCs are discussed for potential applications in optoelectronics and nuclear waste management. One of the drawbacks of the commercial apatite GCs used in orthopedics is the lack of resorbability, therefore the review provides a direction for future research in the field.

  5. Implicit Reasons for Disclosure of the Use of Complementary Health Approaches (CHA): a Consumer Commitment Perspective.

    Science.gov (United States)

    Sirois, Fuschia M; Riess, Helene; Upchurch, Dawn M

    2017-04-21

    Disclosure of the use of complementary health approaches (CHA) is an important yet understudied health behavior with important implications for patient care. Yet research into disclosure of CHA has been atheoretical and neglected the role of health beliefs. Using a consumer commitment model of CHA use as a guiding conceptual framework, the current study tests the hypotheses that perceived positive CHA outcomes (utilitarian values) and positive CHA beliefs (symbolic values) are associated with disclosure of CHA to conventional care providers in a nationally representative US sample. From a sample of 33,594 with CHA use information from the 2012 National Health Interview Survey (NHIS), a subsample of 7348 who used CHA within the past 12 months was analyzed. The 2012 NHIS is a cross-sectional survey of the non-institutionalized US adult population, which includes the most recent nationally representative CHA use data. The 63.2% who disclosed CHA use were older, were less educated, and had visited a health care provider in the past year. Weighted logistic regression analyses controlling for demographic variables revealed that those who disclosed were more likely to report experiencing positive psychological (improved coping and well-being) and physical outcomes (better sleep, improved health) from CHA and hold positive CHA-related beliefs. CHA users who perceive physical and psychological benefits from CHA use and who hold positive attitudes towards CHA are more likely to disclose their CHA use. Findings support the relevance of a consumer commitment perspective for understanding CHA disclosure and suggest CHA disclosure as an important proactive health behavior that warrants further attention.

  6. Adsorption of phenol from an aqueous solution by selected apatite adsorbents: kinetic process and impact of the surface properties.

    Science.gov (United States)

    Bahdod, A; El Asri, S; Saoiabi, A; Coradin, T; Laghzizil, A

    2009-02-01

    Batch adsorption experiments were conducted to investigate the removal of phenol from wastewater by addition of three apatites (porous hydroxyapatite (PHAp) and crystalline hydroxyl- (HAp) and fluoroapatite (FAp)). The best performances were obtained with porous hydroxyapatite PHAp, which presented higher adsorption capacities (experimental: 8.2mgg(-1); calculated 9.2mgg(-1)) than HAp and FAp (3-4mgg(-1)). Different models of adsorption were used to describe the kinetics data, to calculate corresponding rate constants and to predict the theoretical capacities of apatite surfaces for phenol adsorption. A mechanism of phenol adsorption associating chemisorption and physisorption processes is presented allowing the discussion of the variations in adsorption behavior between these materials in terms of specific surface area and chemical composition. These data suggest that apatites are promising materials for phenol sorption.

  7. Dicty_cDB: CHA378 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHA378 (Link to dictyBase) - - - Contig-U12914-1 | Contig-U156...o library) Clone ID CHA378 (Link to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U12...914-1 | Contig-U15635-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/...ed Amino Acid sequence n*NNIINKKMMKANKIIKLFKGTVIHSIEIGKVEILPNSLIGIDEDGVIQHMKSNYEDLK QLEKDVTMICTDNGINEQESVIDM...mino Acid sequence (All Frames) Frame A: n*NNIINKKMMKANKIIKLFKGTVIHSIEIGKVEILPNSLIGIDEDGVIQHMKSNYEDLK QLEKDVTMICT

  8. Apatite and Portland/apatite composite cements obtained using a hydrothermal method for retaining heavy metals.

    Science.gov (United States)

    Domínguez, M I; Carpena, J; Borschnek, D; Centeno, M A; Odriozola, J A; Rose, J

    2008-01-15

    Apatite and Portland/apatite composite cements containing steelwork dusts have been prepared using a low temperature hydrothermal method (200 degrees C, 48h). The produced solids were characterized by means of XRD, IR, and SEM-EDX, and the remaining liquid was analyzed by ICP. The results clearly show the capability of these cements to inertise the heavy metals contained in steelwork dusts, that is Fe, Pb, Mo, Cr, Mn, Ni, and Zn. In the case of apatitic cements, Fe, Mg, Cr, Mn, and Pb coming from steel dust replaced Ca in the divalent cation position of the apatite structure, while Si and Mo replaced P in tetrahedral position. The average crystal size of the apatite-containing dust is smaller than in pure apatite synthesized using the same procedure, which is related to the magnesium content of the dust, since magnesium seems to inhibit the crystal growth. XRD diagrams of composite cements show only peaks corresponding to phases observed in the single cements, and in that no new phases are found. However, EDX analysis reveals the introduction of cations coming from Portland cement into the apatite structure. From the results of water analysis it could be concluded that the capability of retention is higher in composite matrices than in the pure apatite one. In conclusion, the obtained data allow stating that the proposed method, the hydrothermal synthesis of steelwork dust containing cement, is a reliable one for immobilization of toxic residues containing heavy leachable cations.

  9. 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.”

  10. Structural derivation and crystal chemistry of apatites.

    Science.gov (United States)

    White, T J; ZhiLi, Dong

    2003-02-01

    The crystal structures of the [A(1)(2)][A(2)(3)](BO(4))(3)X apatites and the related compounds [A(1)(2)][A(2)(3)](BO(5))(3)X and [A(1)(2)][A(2)(3)](BO(3))(3)X are collated and reviewed. The structural aristotype for this family is Mn(5)Si(3) (D8(8) type, P6(3)/mcm symmetry), whose cation array approximates that of all derivatives and from which related structures arise through the systematic insertion of anions into tetrahedral, triangular or linear interstices. The construction of a hierarchy of space-groups leads to three apatite families whose high-symmetry members are P6(3)/m, Cmcm and P6(3)cm. Alternatively, systematic crystallographic changes in apatite solid-solution series may be practically described as deviations from regular anion nets, with particular focus on the O(1)-A(1)-O(2) twist angle phi projected on (001) of the A(1)O(6) metaprism. For apatites that contain the same A cation, it is shown that phi decreases linearly as a function of increasing average ionic radius of the formula unit. Large deviations from this simple relationship may indicate departures from P6(3)/m symmetry or cation ordering. The inclusion of A(1)O(6) metaprisms in structure drawings is useful for comparing apatites and condensed-apatites such as Sr(5)(BO(3))(3)Br. The most common symmetry for the 74 chemically distinct [A(1)(2)][A(2)(3)](BO(4))(3)X apatites that were surveyed was P6(3)/m (57%), with progressively more complex chemistries adopting P6(3) (21%), P3; (9%), P6 (4.3%), P2(1)/m (4.3%) and P2(1) (4.3%). In chemically complex apatites, charge balance is usually maintained through charge-coupled cation substitutions, or through appropriate mixing of monovalent and divalent X anions or X-site vacancies. More rarely, charge compensation is achieved through insertion/removal of oxygen to produce BO(5) square pyramidal units (as in ReO(5)) or BO(3) triangular coordination (as in AsO(3)). Polysomatism arises through the ordered filling of [001] BO(4) tetrahedral strings to

  11. 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

  12. Electronic and crystallographic structure of apatites

    Science.gov (United States)

    Calderín, L.; Stott, M. J.; Rubio, A.

    2003-04-01

    An ab initio study of four different stoichiometric apatites (oxyapatite, hydroxyapatite, fluorapatite, and chlorapatite) is presented. The calculations were performed using density-functional theory with the local-density approximation for exchange and correlation, and a full relaxation of the electronic structure, the atomic arrangement, and the unit cell. Hexagonal unit cells were obtained for all four apatites, and the calculated atomic arrangements are in close agreement with observation in those cases for which the structure is firmly established. A zero-temperature structure is predicted for oxyapatite, and two possible configurations were found for the Cl- ions in chlorapatite. The possibility of the monoclinic structure in hydroxyapatite and chlorapatite was also studied but no indication of greater stability with respect to the hexagonal structure was found. A relationship between the structure of the apatites and that of pure calcium is discussed.

  13. ChaMAILeon: Simplified email sharing like never before!

    OpenAIRE

    Dewan, Prateek; Gupta, Mayank; Kumaraguru, Ponnurangam

    2013-01-01

    While passwords, by definition, are meant to be secret, recent trends in the Internet usage have witnessed an increasing number of people sharing their email passwords for both personal and professional purposes. As sharing passwords increases the chances of your passwords being compromised, leading websites like Google strongly advise their users not to share their passwords with anyone. To cater to this conflict of usability versus security and privacy, we introduce ChaMAILeon, an experimen...

  14. Can Polyphosphate Biochemistry Affect Biological Apatite Saturation?

    Science.gov (United States)

    Omelon, S. J.; Matsuura, N.; Gorelikov, I.; Wynnyckyj, C.; Grynpas, M. D.

    2010-12-01

    Phosphorus (P) is an important and limiting element for life. One strategy for storing ortho phosphates (Pi) is polymerization. Polymerized Pi's (polyphosphates: (PO3-)n: polyPs) serve as a Pi bank, as well as a catiion chelator, energy source, & regulator of responses to stresses in the stationary phase of culture growth and development1. PolyP biochemistry has been investigated in yeasts, bacteria & plants2. Bigeochemical cycling of P includes the condensation of Pi into pyro (P2O7-4), & polyPs, & the release of Pi from these compounds by the hydrolytic degradation of Pi from phosphomonoester bonds. Alkaline phosphatase (ALP) is one of the predominate enzymes for regenerating Pi in aquatic systems3, & it cleaves Pi from polyPs. ALP is also the enzyme associated with apatite biomineralization in vertebrates4. PolyP was proposed to be the ALP substrate in bone mineralization5. Where calcium ions are plentiful in many aquatic environments, there is no requirement for aquatic life to generate Ca-stores. However, terrestrial vertebrates benefit from a bioavailable Ca-store such as apatite. The Pi storage strategy of polymerizing PO4-3 into polyPs dovetails well with Ca-banking, as polyPs sequester Ca, forming a neutral calcium polyphosphate (Ca-polyP: (Ca(PO3)2)n) complex. This neutral complex represents a high total [Ca+2] & [PO4-3], without the threat of inadvertent apatite precipitation, as the free [Ca+2] & [PO4-3], and therefore apatite saturation, are zero. Recent identification of polyP in regions of bone resorption & calcifying cartilage5 suggests that vertebrates may use polyP chemistry to bank Ca+2 and PO4-3. In vitro experiments with nanoparticulate Ca-polyP & ALP were undertaken to determine if carbonated apatite could precipitate from 1M Ca-polyP in Pi-free “physiological fluid” (0.1 M NaCl, 2 mM Ca+2, 0.8 mM Mg+2, pH ~8.0 ±0.5, 37 °C), as this is estimated to generate the [Ca+2] & [PO4-3] required to form the apatite content of bone tissue

  15. The solution structure of ChaB, a putative membrane ion antiporter regulator from Escherichia coli

    Directory of Open Access Journals (Sweden)

    Iannuzzi Pietro

    2004-08-01

    Full Text Available Abstract Background ChaB is a putative regulator of ChaA, a Na+/H+ antiporter that also has Ca+/H+ activity in E. coli. ChaB contains a conserved 60-residue region of unknown function found in other bacteria, archaeabacteria and a series of baculoviral proteins. As part of a structural genomics project, the structure of ChaB was elucidated by NMR spectroscopy. Results The structure of ChaB is composed of 3 α-helices and a small sheet that pack tightly to form a fold that is found in the cyclin-box family of proteins. Conclusion ChaB is distinguished from its putative DNA binding sequence homologues by a highly charged flexible loop region that has weak affinity to Mg2+ and Ca2+ divalent metal ions.

  16. Syntheses of 11-hydroxylated guaianolides

    DEFF Research Database (Denmark)

    Lauridsen, A.; Cornett, Claus; Vulpius, T.

    1996-01-01

    Two epimeric guaianolides, both prepared from alpha-santonin, were 11-hydroxylated using 2-phenylsulfonyl-3-phenyloxaziridine as a reagent. Extensive use of protecting groups enabled selective acylation of the 3- and 10-hydroxy groups....

  17. MID-INFRARED VARIABILITY OF THE BINARY SYSTEM CS Cha

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, Erick [Departamento de Astronomia, Universidad de Guanajuato, Guanajuato, Gto 36240 (Mexico); Espaillat, Catherine [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); D' Alessio, Paola [Centro de Radioastronomia y Astrofisica, UNAM, Morelia, Michoacan 58089 (Mexico); Calvet, Nuria, E-mail: erick@astro.ugto.mx [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

    2012-03-10

    CS Cha is a binary system surrounded by a circumbinary disk. We construct a model for the inner disk regions and compare the resulting synthetic spectral energy distribution (SED) with Infrared Spectrograph spectra of CS Cha taken at two different epochs. For our model, we adopt a non-axisymmetric mass distribution from results of published numerical simulations of the interaction between a circumbinary disk and a binary system, where each star is surrounded by a disk. In particular, we approximate the streams of mass from which the inner circumstellar disks accrete from the circumbinary disk. This structure is due to the gravitational interaction of the stars with the disk, in which an array of disks and streams is formed in an inner hole. We calculate the temperature distribution of the optically thin dust in these inner regions considering the variable impinging radiation from both stars and use the observations to estimate the mass variations in the streams. We find that the SEDs for both epochs can be explained with emission from an optically thick inner edge of the circumbinary disk and from the optically thin streams that connect the circumbinary disk with the two smaller circumstellar disks. To the best of our knowledge, this is the first time that the emission from the optically thin material in the hole, suggested by the theory, is tested against observations of a binary system.

  18. Chaîne de blocs | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    interagir avec les autres, et les données de la chaîne de blocs sont encryptées. Les chaînes de blocs peuvent être publiques ou ouvertes à tous (comme c'est le cas pour Bitcoin et Ethereum), ou privées, comme c'est le cas pour ...

  19. Chitosan/apatite composite beads prepared by in situ generation of apatite or Si-apatite nanocrystals.

    Science.gov (United States)

    Davidenko, Natalia; Carrodeguas, Raúl G; Peniche, Carlos; Solís, Yaimara; Cameron, Ruth E

    2010-02-01

    The objective of this work was to develop nanocrystalline apatite (Ap) dispersed in a chitosan (CHI) matrix as a material for applications in bone tissue engineering. CHI/Ap composites of different weight ratios (20/80, 50/50 and 80/20) and with CHI of different molecular weights were prepared by a biomimetic stepwise route. Firstly, CaHPO(4).2H(2)O (DCPD) crystals were precipitated from Ca(CH(3)COO)(2) and NaHPO(4) in the bulk CHI solution, followed by the formation of CHI/DCPD beads by coacervation. The beads were treated with Na(3)PO(4)/Na(5)P(3)O(10) solution (pH 12-13) to crosslink the CHI and to hydrolyse the DCPD to nanocrystalline Ap. This new experimental procedure ensured that complete conversion of DCPD into sodium-substituted apatite was achieved without appreciable increases in its crystallinity and particle size. In addition, composites with silicon-doped Ap were prepared by substituting Na(3)PO(4) by Na(2)SiO(3) in the crosslinking/hydrolysis step. Characterization of the resultant composites by scanning electron microscopy, X-ray powder diffraction (XRD), thermal analysis and Fourier transform infrared spectroscopy confirmed the formation, within the CHI matrix, of nanoparticles of sodium- and carbonate-substituted hydroxyapatite [Ca(10-x)Na(x)(PO(4))(6-x)(CO(3))(x)(OH)(2)] with diameters less than 20nm. Relatively good correspondence was shown between the experimentally determined inorganic content and that expected theoretically. Structural data obtained from its XRD patterns revealed a decrease in both crystal domain size and cell parameters of Ap formed in situ with increasing CHI content. It was found that the molecular weight of CHI and silicate doping both affected the nucleation and growth of apatite nanocrystallites. These effects are discussed in detail.

  20. 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)

  1. Searching for Molecular Filaments in the CHaMP Survey

    Science.gov (United States)

    Gabaldon, Charris

    2018-01-01

    It is known that protostars form in cold, dense cloud regions of the Milky Way. However, these surrounding areas, known as molecular filament structures, have not been thoroughly studied. Once more is understood about these areas, more can be discovered about star formation.Most of the previous work done on these filamentary structures has used surveys from the Northern Hemisphere and little work has been done in the Southern Hemisphere.The CHaMP survey is one of the few Southern Hemisphere surveys. However, it was not a full sky survey, thus, it was much trickier to find long filamentary structures.The research has shown that only having chunks of sky to analyze can still result in the identification of filamentary shapes and can thus save astronomers time when surveying the sky as non full sky surveys can still be used to understand larger structures in the galaxy.

  2. Distribution of halogens during fluid-mediated apatite replacement

    Science.gov (United States)

    Kusebauch, Christof; John, Timm; Whitehouse, Martin J.

    2016-04-01

    Apatite (Ca5(PO4)3(F,Cl,OH)) is one the most abundant halogen containing minerals in the crust. It is present in many different rock types and stable up to P-T conditions of the mantle. Although probably not relevant for the halogen budget of the mantle, apatite is potentially a carrier phase of halogens into the mantle via subduction processes and therefore important for the global halogen cycle. Different partitioning behavior of the halogens between apatite and melt/fluids causes fractionation of these elements. In hydrothermal environments apatite reacts via a coupled dissolution-reprecipitation process that leads to apatite halogen compositions which are in (local) equilibrium with the hydrothermal fluid. This behavior enables apatite to be used as fluid probe and as a tool for tracking fluid evolution during fluid-rock interaction. Here, we present a combined experimental and field related study focused on replacement of apatite under hydrothermal conditions, to investigate the partitioning of halogens between apatite and fluids. Experiments were conducted in a cold seal pressure apparatus at 0.2 GPa and temperatures ranging from 400-700°C using halogen bearing solutions of different composition (KOH, NaF, NaCl, NaBr, NaI) to promote the replacement of Cl-apatite. The halogen composition of reacted apatite was analyzed by electron microprobe (EMPA) and secondary ion mass spectrometry (SIMS). The data was used to calculate partition coefficients of halogens between fluid and apatite. Our new partitioning data show that fluorine is the most compatible halogen followed by chlorine, bromine and iodine. Comparison between partition coefficients of the apatite-fluid system and coefficients derived in the apatite-melt system reveals values for F that are one to two orders of magnitude higher. In contrast, Cl and Br show a similar partition behavior in fluid and melt systems. Consequently, apatite that formed by fluid-rock interaction will fractionate F from Cl more

  3. Diffusion of hydroxyl ions from calcium hydroxide and Aloe vera pastes.

    Science.gov (United States)

    Batista, Victor Eduardo de Souza; Olian, Douglas Dáquila; Mori, Graziela Garrido

    2014-01-01

    This study evaluated the diffusion through the dentinal tubules of hydroxyl ions from different calcium hydroxide (CH) pastes containing Aloe vera. Sixty single-rooted bovine teeth were used. The tooth crowns were removed, the root canals were instrumented and the specimens were assigned to 4 groups (n=15) according to the intracanal medication: Group CH/S - CH powder and saline paste; Group CH/P - CH powder and propylene glycol paste; Group CH/A - calcium hydroxide powder and Aloe vera gel paste; Group CH/A/P - CH powder, Aloe vera powder and propylene glycol paste. After placement of the root canal dressings, the teeth were sealed coronally and apically with a two-step epoxy adhesive. The teeth were placed in identified flasks containing deionized water and stored in an oven with 100% humidity at 37 °C. After 3 h, 24 h, 72 h, 7 days, 15 days and 30 days, the deionized water in the flasks was collected and its pH was measured by a pH meter. The obtained data were subjected to statistical analysis at a significance level of 5%. The results demonstrated that all pastes provided diffusion of hydroxyl ions through the dentinal tubules. The combination of Aloe vera and CH (group CH/A) provided a constant release of calcium ions. Group CH/A/P showed the highest pH at 24 and 72 h. In conclusion, the experimental pastes containing Aloe vera were able to enable the diffusion of hydroxyl ions through the dentinal tubules.

  4. Chemical vapor deposition on chabazite (CHA) zeolite membranes for effective post-combustion CO2 capture.

    Science.gov (United States)

    Kim, Eunjoo; Lee, Taehee; Kim, Hyungmin; Jung, Won-Jin; Han, Doug-Young; Baik, Hionsuck; Choi, Nakwon; Choi, Jungkyu

    2014-12-16

    Chabazite (CHA) zeolites with a pore size of 0.37 × 0.42 nm(2) are expected to separate CO2 (0.33 nm) from larger N2 (0.364 nm) in postcombustion flue gases by recognizing their minute size differences. Furthermore, the hydrophobic siliceous constituent in CHA membranes can allow for maintaining the CO2/N2 separation performance in the presence of H2O in contrast with the CO2 affinity-based membranes. In an attempt to increase the molecular sieving ability, the pore mouth size of all silica CHA (Si-CHA) particles was reduced via the chemical vapor deposition (CVD) of a silica precursor (tetraethyl orthosilicate). Accordingly, an increase of the CVD treatment duration decreased the penetration rate of CO2 into the CVD-treated Si-CHA particles. Furthermore, the CVD process was applied to siliceous CHA membranes in order to improve their CO2/N2 separation performance. Compared to the intact CHA membranes, the CO2/N2 maximum separation factor (max SF) for CVD-treated CHA membranes was increased by ∼ 2 fold under dry conditions. More desirably, the CO2/N2 max SF was increased by ∼ 3 fold under wet conditions at ∼ 50 °C, a representative temperature of the flue gas stream. In fact, the presence of H2O in the feed disfavored the permeation of N2 more than that of CO2 through CVD-modified CHA membranes and thus, contributed to the increased CO2/N2 separation factor.

  5. ESR detection of ROS generated by TiO2 coated with fluoridated apatite.

    Science.gov (United States)

    Sawada, Tomofumi; Yoshino, F; Kimoto, K; Takahashi, Y; Shibata, T; Hamada, N; Sawada, Tomoji; Toyoda, M; Lee, M-C

    2010-08-01

    Specific materials used in the manufacture of dentures may enhance the removal of micro-organisms. The ultraviolet A (UVA) irradiation of acrylic resin containing titanium dioxide (TiO(2)) generates reactive oxygen species (ROS) by photocatalysis that shows antibacterial effects. In this study, we tested the hypothesis that TiO(2) coated with fluoridated apatite (FAp-TiO(2)) can generate ROS via photo-catalysis by using electron spin resonance (ESR), and that acrylic resin containing FAp-TiO(2) can show antifungal properties by measuring the viability of Candida albicans. We demonstrated that hydroxyl radicals (HO(*)) were generated through excitation of TiO(2), TiO(2) coated with apatite (HAp-TiO(2)), and FAp-TiO(2). The HO(*) generation through excitation of FAp-TiO(2) was higher than that of TiO(2) and HAp-TiO(2). Regarding antifungal activity, cell viability on acrylic resin containing FAp-TiO(2) was lower than that of TiO(2) and HAp-TiO(2). FAp-TiO(2) showed superior photocatalytic effects, and these characteristics may lead to novel methods for the clinical application of denture-cleaning treatments.

  6. IN SITU LEAD STABILIZATION USING NATURAL AND SYNTHETIC APATITE

    Directory of Open Access Journals (Sweden)

    T. Kaluđerović Radoičić

    2008-11-01

    Full Text Available In this work, mineral apatite was investigated for the remediation of lead contamination. Two different apatite minerals were used: synthetic apatite, Ca10(PO46(OH2 (hereafter denoted as HAP and natural apatite from Lisina, near Bosilegrad, Serbia (hereafter denoted as LA. Phosphate ore from Lisina deposit consists of 43.3 % apatite in the form of fluorapatite, Ca10(PO46(F2. Sorption properties of HAP and LA were investigated. The results show that both of these minerals are effective in lead removal from the water solution. Sorption capacity of HAP obtained in this experiment is 0.216 mmol Pb/g HAP, while the value for LA is 0.162 mmol Pb/g LA. Modeling of these systems was conducted using Visual Minteq computer program. The values obtained from the computer simulation were compared to experimental values.

  7. Finding the Patient's Voice Using Big Data: Analysis of Users' Health-Related Concerns in the ChaCha Question-and-Answer Service (2009-2012).

    Science.gov (United States)

    Priest, Chad; Knopf, Amelia; Groves, Doyle; Carpenter, Janet S; Furrey, Christopher; Krishnan, Anand; Miller, Wendy R; Otte, Julie L; Palakal, Mathew; Wiehe, Sarah; Wilson, Jeffrey

    2016-03-09

    The development of effective health care and public health interventions requires a comprehensive understanding of the perceptions, concerns, and stated needs of health care consumers and the public at large. Big datasets from social media and question-and-answer services provide insight into the public's health concerns and priorities without the financial, temporal, and spatial encumbrances of more traditional community-engagement methods and may prove a useful starting point for public-engagement health research (infodemiology). The objective of our study was to describe user characteristics and health-related queries of the ChaCha question-and-answer platform, and discuss how these data may be used to better understand the perceptions, concerns, and stated needs of health care consumers and the public at large. We conducted a retrospective automated textual analysis of anonymous user-generated queries submitted to ChaCha between January 2009 and November 2012. A total of 2.004 billion queries were read, of which 3.50% (70,083,796/2,004,243,249) were missing 1 or more data fields, leaving 1.934 billion complete lines of data for these analyses. Males and females submitted roughly equal numbers of health queries, but content differed by sex. Questions from females predominantly focused on pregnancy, menstruation, and vaginal health. Questions from males predominantly focused on body image, drug use, and sexuality. Adolescents aged 12-19 years submitted more queries than any other age group. Their queries were largely centered on sexual and reproductive health, and pregnancy in particular. The private nature of the ChaCha service provided a perfect environment for maximum frankness among users, especially among adolescents posing sensitive health questions. Adolescents' sexual health queries reveal knowledge gaps with serious, lifelong consequences. The nature of questions to the service provides opportunities for rapid understanding of health concerns and may

  8. Favoriser le développement de chaînes de valeur agricoles ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ce projet vise à mettre l'information et les connaissances au service du développement de chaînes de valeur agricoles grâce à l'utilisation stratégique des TIC. Les chercheurs analyseront cinq chaînes de valeur agricoles (café, cacao, légumes, miel et fèves) dans trois pays d'Amérique centrale (le Salvador, le Honduras et ...

  9. CHaMP: From Molecular Clouds to Massive Young Clusters

    Science.gov (United States)

    Barnes, Peter J.

    2017-03-01

    I review the major science outcomes to date of the Galactic Census of High- and Medium-mass Protostars (CHaMP), and also report the latest observational results on this unbiased, uniform sample of massive, cluster-forming molecular clumps, based on new mm-wave and IR data. These clouds represent the vast, subthermally-excited population of clumps predicted by Narayanan et al. (2008) to dominate the molecular mass of disk galaxies. Besides confirming their existence, we have presented evidence that these massive clumps probably spend a large fraction (90-95%) of their long lives (possibly up to 100 Myr) in a mostly quiescent, low star formation rate (SFR) state. This is likely ended when a density or internal pressure threshold is crossed, after which vigorous, massive cluster formation consumes the densest gas with a high SFR, dispersing the embedding envelope. New results presented in two other posters at this Symposium include (1) the first analysis of HCN emission from the dense gas (Schap et al. 2015), and (2) the first deep photometry of clusters in this sample based on NIR AAT & CTIO data, and on MIR Warm Spitzer IRAC data (Dallilar et al. 2015).

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

    Science.gov (United States)

    Saita, Makiko; Ikeda, Takayuki; Yamada, Masahiro; Kimoto, Katsuhiko; Lee, Masaichi Chang-Il; Ogawa, Takahiro

    2016-01-01

    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 in the valleys and at the inclines of micro-roughened structures without affecting the existing micro-configuration. Micro-roughened titanium and apatite-deposited titanium surfaces had similar roughness values. The attachment, spreading, settling, proliferation, and alkaline phosphate activity of bone marrow-derived osteoblasts were promoted on apatite-coated titanium with photofunctionalization. Conclusion UV-photofunctionalization of titanium enabled faster deposition of nanoscale biomimetic apatite, resulting in the improved biological capability compared to the similarly prepared apatite-deposited titanium without photofunctionalization. Photofunctionalization-assisted biomimetic apatite

  11. Genesis of iron-apatite ores in Posht-e-Badam Block (central Iran ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 122; Issue 3. Genesis of iron-apatite ores in Posht-e-Badam Block (central ... 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 ...

  12. 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.)

  13. Prolyl hydroxylation in elastin is not random.

    Science.gov (United States)

    Schmelzer, Christian E H; Nagel, Marcus B M; Dziomba, Szymon; Merkher, Yulia; Sivan, Sarit S; Heinz, Andrea

    2016-10-01

    This study aimed to investigate the prolyl and lysine hydroxylation in elastin from different species and tissues. Enzymatic digests of elastin samples from human, cattle, pig and chicken were analyzed using mass spectrometry and bioinformatics tools. It was confirmed at the protein level that elastin does not contain hydroxylated lysine residues regardless of the species. In contrast, prolyl hydroxylation sites were identified in all elastin samples. Moreover, the analysis of the residues adjacent to prolines allowed the determination of the substrate site preferences of prolyl 4-hydroxylase. It was found that elastins from all analyzed species contain hydroxyproline and that at least 20%-24% of all proline residues were partially hydroxylated. Determination of the hydroxylation degrees of specific proline residues revealed that prolyl hydroxylation depends on both the species and the tissue, however, is independent of age. The fact that the highest hydroxylation degrees of proline residues were found for elastin from the intervertebral disc and knowledge of elastin arrangement in this tissue suggest that hydroxylation plays a biomechanical role. Interestingly, a proline-rich domain of tropoelastin (domain 24), which contains several repeats of bioactive motifs, does not show any hydroxyproline residues in the mammals studied. The results show that prolyl hydroxylation is not a coincidental feature and may contribute to the adaptation of the properties of elastin to meet the functional requirements of different tissues. The study for the first time shows that prolyl hydroxylation is highly regulated in elastin. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. 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.

  15. A tephrochronologic method based on apatite trace-element chemistry

    Science.gov (United States)

    Sell, Bryan Keith; Samson, Scott Douglas

    Geochemical correlation of ash-fall beds with conventional tephrochronologic methods is not feasible when original glass composition is altered. Thus, alternative correlation methods may be required. Initial studies of heavily altered Paleozoic tephra (K-bentonites) have suggested the potential for employing trace-element concentrations in apatite as ash-fall bed discriminators. To further test the utility of apatite trace-element tephrochronology, we analyzed apatite phenocrysts from unaltered volcanic rocks with an electron microprobe: nine samples from rocks erupted during the Quaternary and one sample from a rock erupted during the Paleogene. The resulting apatite trace-element data provide unique bed discriminators despite within-crystal variability. Each of the volcanic rocks studied possesses unique trends in Mg, Cl, Mn, Fe, Ce and Y concentrations in apatite. The results from this study establish an important tephrochronologic method that can be applied to nearly all portions of the Phanerozoic stratigraphic record and greatly assist development of an advanced timescale. In addition to establishing a fingerprint for a particular eruption, apatite chemistry provides useful information about the source magma.

  16. Apatite mineralization in elasmobranch skeletons via a polyphosphate intermediate

    Science.gov (United States)

    Omelon, Sidney; Lacroix, Nicolas; Lildhar, Levannia; Variola, Fabio; Dean, Mason

    2014-05-01

    All vertebrate skeletons are stiffened with apatite, a calcium phosphate mineral. Control of apatite mineralization is essential to the growth and repair of the biology of these skeletons, ensuring that apatite is deposited in the correct tissue location at the desired time. The mechanism of this biochemical control remains debated, but must involve increasing the localized apatite saturation state. It was theorized in 1923 that alkaline phosphatase (ALP) activity provides this control mechanism by increasing the inorganic phosphate (Pi) concentration via dephosphorylation of phosphorylated molecules. The ALP substrate for biological apatite is not known. We propose that polyphosphates (polyPs) produced by mitochondria may be the substrate for biological apatite formation by ALP activity. PolyPs (PO3-)n, also known as condensed phosphates, represent a concentrated, bioavailable Pi-storage strategy. Mitochondria import Pi and synthesize phosphate polymers through an unknown biochemical mechanism. When chelated with calcium and/or other cations, the effective P-concentration of these neutrally charged, amorphous, polyP species can be very high (~ 0.5 M), without inducing phosphate mineral crystallization. This P-concentration in the low Pi-concentration biological environment offers a method of concentrating P well above an apatite supersaturation required for nucleation. Bone is the most studied mineralized skeletal tissue. However, locating and analyzing active mineralizing areas is challenging. We studied calcified cartilage skeletons of elasmobranch fishes (sharks, stingrays and relatives) to analyse the phosphate chemistry in this continually mineralizing skeleton. Although the majority of the elasmobranch skeleton is unmineralized cartilage, it is wrapped in an outer layer of mineralized tissue comprised of small tiles called tesserae. These calcified tesserae continually grow through the formation of new mineral on their borders. Co-localization of ALP and

  17. 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

  18. Analyse et évaluation de la chaîne logistique automobile marocaine

    OpenAIRE

    RAHOUM, khadija; JAMOULI, Hicham; BADDOU, ATMANE

    2015-01-01

    International audience; Dans un premier temps, notre article s'intéresse, au contexte industriel du secteur automobile au Maroc, à la problématique de la sous exploitation de la fonction logistique chez les équipementiers automobiles de type PME, et la difficulté de leur intégration et collaboration dans la chaîne logistique globale du constructeur CKD (Completely Knocked Down). Ensuite, nous présentons une revue de la littérature résumant les différents modèles d'évaluation de la chaîne logi...

  19. ChaLearn Looking at People: A Review of Events and Resources

    OpenAIRE

    Escalera, Sergio; Baró, Xavier; Escalante, Hugo Jair; Guyon, Isabelle

    2017-01-01

    This paper reviews the historic of ChaLearn Looking at People (LAP) events. We started in 2011 (with the release of the first Kinect device) to run challenges related to human action/activity and gesture recognition. Since then we have regularly organized events in a series of competitions covering all aspects of visual analysis of humans. So far we have organized more than 10 international challenges and events in this field. This paper reviews associated events, and introduces the ChaLearn ...

  20. Functionalization of hydroxyl terminated polybutadiene with ...

    Indian Academy of Sciences (India)

    ... hydroxyl value and microstructure of the parent HTPB. The formation of hydrogen bonding between the terminal hydroxyl groups and the nitrogen atoms of triazine moiety is the driving force for the terminal attachment chemistry. The functionalized HTPB (HTPB–CBDT) shows a strong fluorescence emission at 385 nm.

  1. Prolyl hydroxylation in elastin is not random

    DEFF Research Database (Denmark)

    Schmelzer, Christian E H; Nagel, Marcus B M; Dziomba, Szymon

    2016-01-01

    at the protein level that elastin does not contain hydroxylated lysine residues regardless of the species. In contrast, prolyl hydroxylation sites were identified in all elastin samples. Moreover, the analysis of the residues adjacent to prolines allowed the determination of the substrate site preferences...

  2. 78 FR 76406 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel CHA-SON; Invitation for...

    Science.gov (United States)

    2013-12-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Requested Administrative Waiver of the Coastwise Trade Laws: Vessel CHA-SON... of the vessel CHA-SON is: Intended Commercial Use of Vessel: ``Ocean charter fishing on the nearshore...

  3. Isotropic radical CO{sub 2}{sup -} in biological apatites

    Energy Technology Data Exchange (ETDEWEB)

    Rudko, V.V. [Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, 45, pr. Nauky, Kiev 03028 (Ukraine)], E-mail: vv_rudko@yahoo.com; Ishchenko, S.S.; Vorona, I.P.; Baran, N.P. [Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, 45, pr. Nauky, Kiev 03028 (Ukraine)

    2007-10-15

    The isotropic CO{sub 2}{sup -} EPR spectrum at g{approx}2.0006 for {gamma}-irradiated powders of dental enamel annealed at different temperatures up to 320{sup 0}C is studied. The signal intensity is found to increase with the growth of annealing temperature up to 240{sup 0}C. This finding contradicts to the existing model of isotropic CO{sub 2}{sup -} radical in apatites. The possible models of the radical in biological apatite are analyzed and discussed. On the basis of the results obtained it is suggested that in tooth enamel apatite the isotropic CO{sub 2}{sup -} radical is the bulk radical localized in structural voids of hydroxyapatite lattice, which occur in the vicinity of a carbon radical in position B.

  4. Tetracycline-loaded biomimetic apatite: an adsorption study.

    Science.gov (United States)

    Cazalbou, Sophie; Bertrand, Ghislaine; Drouet, Christophe

    2015-02-19

    Biomimetic apatites are appealing compounds for the elaboration of bioactive bone-repair scaffolds due to their intrinsic similarity to bone mineral. Bone surgeries are however often heavy procedures, and the infiltration of pathogens may not be totally avoided. To prevent their development, systemic antibiotic prophylaxis is widespread but does not specifically target surgical sites and involves doses not always optimized. A relevant alternative is a preliminary functionalization by an infection-fighting agent. In this work, we investigated from a physicochemical viewpoint the association of a wide-spectrum antibiotic, tetracycline (TC), and a biomimetic nanocrystalline apatite previously characterized. TC adsorption kinetics and isotherm were thoroughly explored. Kinetic data were fitted to various models (pseudo-first-order, pseudo-second-order, general kinetic model of order n, Elovich, double-exponential, and purely diffusive models). The best fit was found for a double-exponential kinetic model or with a decimal reaction order of 1.4, highlighting a complex process with such TC molecules which do not expose high-affinity end groups for the surface of apatite. The adsorption isotherm was perfectly fitted to the Sips (Langmuir-Freundlich) model, while other models failed to describe it, and the Sips exponent greater than unity (1.08) suggested a joint impact of surface heterogeneity and positive cooperativity between adsorbed molecules. Finally, preliminary insights on TC release from pelletized nanocrystalline apatite, in aqueous medium and neutral pH, were obtained using a recirculation cell, indicating a release profile mainly following a Higuchi-like diffusion-limited rate. This work is intended to shed more light on the interaction between polar molecules not exhibiting high-affinity end groups and biomimetic apatites and is a starting point in view of the elaboration of biomimetic apatite-based bone scaffolds functionalized with polar organic drugs for a

  5. Biological activity of tri-calciumphosphate/hydroxyl-apatite granules mixed with impacted morsellized bone graft. A study in rabbits.

    NARCIS (Netherlands)

    Arts, J.J.C.; Walschot, L.H.B.; Verdonschot, N.J.J.; Schreurs, B.W.; Buma, P.

    2007-01-01

    Reconstruction of bone defects with impacted morsellized cancellous bone grafts (MCB) is a popular method. Because of a shortage of human bone, mixing with biomaterials may be attractive. Ceramics may be used as bone graft extenders. In this study, various volume mixtures of biphasic

  6. Adhesive strength of hydroxyl apatite(HA coating and biomechanics behavior of HA-coated prosthesis:an experimental study

    Directory of Open Access Journals (Sweden)

    Tian-yang ZHANG

    2011-05-01

    Full Text Available Objective To explore the influence of adhesive strength of hydroxyapatite(HA coating on the post-implantation stability of HA-coated prosthesis.Methods The adhesive strength and biomechanics behavior of HA coating were studied by histopathological observation,material parameters and biomechanical testing,the titanium(Ti-coated prosthesis was employed as control.Results Scratch test showed that the adhesive strength of HA coating was significantly lower than that of Ti coating(P < 0.01.Histopathological examination and bone morphometry showed that,at the early stage of prosthesis implantation,the bony growth around HA-coated prosthesis was significantly higher than that around Ti-coated prosthesis(P < 0.01,but the ultimate shear strength of HA-coated prosthesis was much lower than that of Ti-coated prosthesis(P < 0.01.After the push-out test with prosthesis,histopathological observation showed that there were accumulations of clump-and strip-like granular residues on the surface of bones that newly grew around the HA-coated prosthesis,and surface energy-dispersive X-ray spectroscopy(EDX analysis also confirmed that the shear stress induced HA decohesion from the substrate of prosthesis.Conclusions Although HA coating showed a satisfactory effect on early bone formation and prosthetic stability,due to the deficiencies of adhesive strength,the early stability of prosthesis may be gradually destroyed by the shear loads of human body and coating degradation.

  7. Chemical, physical, and histologic studies on four commercial apatites used for alveolar ridge augmentation

    DEFF Research Database (Denmark)

    Pinholt, E M; Ruyter, I E; Haanaes, H R

    1992-01-01

    characteristics obtained by chemical analysis and infrared spectrometry. None of the apatites caused osteoinduction or osteoconduction; fibrous encapsulation with multinuclear giant cells was observed around all four types. One of the apatites was fluorapatite and not hydroxylapatite, as claimed...

  8. Amélioration des chaînes de valeur de la production alimentaire par ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Toutefois, bon nombre de ces initiatives omettent d'intégrer la production et les priorités des femmes au développement des chaînes de valeur. Ce projet de ... Post-Harvest Management Technologies for Reducing Aflatoxin Contamination in Maize Grain and Exposure to Humans in Zimbabwe. This project seeks to ...

  9. Coordination Environment of Copper Sites in Cu-CHA Zeolite Investigated by Electron Paramagnetic Resonance

    DEFF Research Database (Denmark)

    Godiksen, Anita; Stappen, Frederick N.; Vennestrøm, Peter N. R.

    2014-01-01

    the zeolite framework is very simple with only one crystallographically independent tetrahedral site (T-site). In this study the results of an X-band electron paramagnetic resonance (EPR) investigation of ion-exchanged Cu-CHA zeolite with a Si/Al ratio of 14 ± 1 is presented. Different dehydration treatments...

  10. Simultaneous incorporation of magnesium and carbonate in apatite: effect on physico-chemical properties

    OpenAIRE

    Sader,Marcia S.; Kanthi Lewis; Soares, Gloria A.; Racquel Z. LeGeros

    2013-01-01

    Synthetic apatites are widely used both in the dental and the orthopaedic fields due to their similarity in composition with the inorganic phase of hard tissues. Biologic apatites are not pure hydroxyapatite (HA), but are calcium-deficient apatites with magnesium and carbonate as minor but important substituents. The aim of the present study was to produce a more soluble biomaterial through the simultaneous substitution of magnesium and carbonate in the apatite structure to accelerate the deg...

  11. Genesis of iron-apatite ores in Posht-e-Badam Block (Central Iran ...

    Indian Academy of Sciences (India)

    intrusions around some of the iron-apatite deposits that are petrographically identified as syenite and gabbro. These intrusions also have REE .... system for the Posht-e-Badam Block iron-apatite ores based on geochemistry of apatite, .... magnetite at the Lakeh-Siah deposit. The detection limits for analyzing these elements.

  12. Hydroxyl Tagging Velocimetry for Rocket Plumes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A non-intrusive method for measuring velocities in a rocket exhaust is proposed in a joint effort by MetroLaser and Vanderbilt University. Hydroxyl Tagging...

  13. An ab initio study of hydroxylated graphane

    Science.gov (United States)

    Buonocore, Francesco; Capasso, Andrea; Lisi, Nicola

    2017-09-01

    Graphene-based derivatives with covalent functionalization and well-defined stoichiometry are highly desirable in view of their application as functional surfaces. Here, we have evaluated by ab initio calculations the energy of formation and the phase diagram of hydroxylated graphane structures, i.e., fully functionalized graphene derivatives coordinated with -H and -OH groups. We compared these structures to different hydrogenated and non-hydrogenated graphene oxide derivatives, with high level of epoxide and hydroxyl groups functionalization. Based on our calculations, stable phases of hydroxylated graphane with low and high contents of hydrogen are demonstrated for high oxygen and hydrogen partial pressure, respectively. Stable phases of graphene oxide with a mixed carbon hybridization are also found. Notably, the synthesis of hydroxylated graphane has been recently reported in the literature.

  14. Electronic structure and bonding in calcium apatite crystals: Hydroxyapatite, fluorapatite, chlorapatite, and bromapatite

    Science.gov (United States)

    Rulis, Paul; Ouyang, Lizhi; Ching, W. Y.

    2004-10-01

    We present a detailed analysis of the electronic structure, bonding, charge transfer, and optical properties of selected perfect-crystal calcium apatites [ Ca10(PO4)6X2 with X=(OH)-,F-,Cl- , or Br- ]. The ab initio orthogonalized linear combinations of atomic orbitals-density-functional-theory-based computational method is used to obtain the band structure, total and partial density of states, bond order, Mulliken effective charge, dielectric constant, and energy-loss function for each system. Band results indicate that these materials are all wide band-gap insulators in the range of ˜5.3eV . The bonding results show that the systems are dominated by two sets of structures: a PO4 sublattice and Ca channels populated by ion columns of X . The exact positions and orientations of the ions in the Ca channels are subject to debate on many levels. To contribute to the discussion, we analyze the position and orientation of the hydroxyl group from hydroxyapatite along the Ca channel using total-energy comparisons.

  15. Nano-apatite/polymer composites: mechanical and physicochemical characteristics

    NARCIS (Netherlands)

    Liu, Qing; de Wijn, J.R.; van Blitterswijk, Clemens

    1997-01-01

    Hydrothermally synthesized acicular nano-apatite (Nap) was used as filler to make composites with a polyethylene glycol/poly(butylene terephthalate) (PEG/PBT) block copolymer (Polyactive™70:30). The Nap had a particle diameter of 9–25 nm and a length of 80–200 nm. The mechanical properties and the

  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. Trace Element Abundances in Extraterrestrial Apatite and Merrillite

    Science.gov (United States)

    Ward, D.; Bischoff, A.; Roszjar, J.; Berndt, J.; Whitehouse, M. J.

    2016-08-01

    The trace element abundances (Sc, Ti, V, Cr, Mn, Co, As, Rb, Sr, Y, Zr, Nb, Ba, Hf, Ta, Pb, Th, U, as well as the REE) of 133 apatite and 163 merrillite grains from 24 meteorites, covering 9 different classes were analyzed by LA-ICP-MS and SIMS.

  18. Gene Delivery via DNA Incorporation Within a Biomimetic Apatite Coating

    Science.gov (United States)

    Luong, L. N.; McFalls, K. M.; Kohn, D. H.

    2009-01-01

    Integrating inductivity with conductivity in a material may advance tissue engineering. An organic/inorganic hybrid was developed by incorporating plasmid DNA encoding for the β-gal gene complexed with Lipofectamine 2000® (DNA-Lipoplex) within apatite via coprecipitation. It is hypothesized that this system will result in enhanced transfection efficiency compared to DNA-Lipoplexes adsorbed to the mineral surface and DNA coprecipitated without Lipofectamine 2000®. PLGA films were cast onto glass slips and apatite and DNA were coprecipitated in modified simulated body fluid (mSBF). DNA-Lipoplex presence in mineral, DNA-Lipoplex stability (vs. coprecipitation time), and transfection efficiency (determined with C3H10T1/2 cells) as a function of coprecipitation time, DNA-Lipoplex concentration, and DNA incorporation method were studied. DNA-Lipoplex presence and spatial distribution on apatite were confirmed through fluorescence. Transfection efficiency was highest for 6 h of DNA- Lipoplex coprecipitation. Differences in transfection efficiency were found between the DNA concentrations, with the highest efficiency for coprecipitation being 40 μg/ml (p≤0.009 relative to other coprecipitation concentrations). Significant differences in transfection efficiency existed between incorporation methods (p<0.05) with the highest efficiency for DNA-Lipoplex coprecipitation. This hybrid material system not only integrates inductivity provided by the DNA and conductivity provided by the apatite, but it also has significant implications in non-viral gene delivery due to its ability to increase transfection efficiency. PMID:19775750

  19. Apatite: a new redox proxy for silicic magmas?

    Science.gov (United States)

    Miles, Andrew; Graham, Colin; Hawkesworth, Chris; Gillespie, Martin; Bromiley, Geoff; Hinton, Richard

    2015-04-01

    The oxidation states of magmas provide valuable information about the release and speciation of volatile elements during volcanic eruptions, metallogenesis, source rock compositions, open system magmatic processes, tectonic settings and potentially titanium (Ti) activity in chemical systems used for Ti-dependent geothermometers and geobarometers. In this presentation we explore the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks. Increased Mn concentrations in apatite in granitic rocks from the zoned Criffell granitic pluton (southern Scotland) correlate with decreasing Fe2O3 (Fe3+) and Mn in the whole-rock and likely reflect increased Mn2+/Mn3+and greater compatibility of Mn2+ relative to Mn3+ in apatite under reduced conditions. Fe3+/Fe2+ ratios in biotites have previously been used to calculate oxygen fugacities (fO2) in the outer zone granodiorites and inner zone granites where redox conditions have been shown to change from close to the magnetite-hematite buffer to close to the nickel-nickel oxide buffer respectively[1]. This trend is apparent in apatite Mn concentrations from a range of intermediate to silicic volcanic rocks that exhibit varying redox states and are shown to vary linearly and negatively with log fO2, such that logfO2=-0.0022(±0.0003)Mn(ppm)-9.75(±0.46) Variations in the Mn concentration of apatites appear to be largely independent of differences in the Mn concentration of the melt. Apatite Mn concentrations may therefore provide an independent oxybarometer that is amenable to experimental calibration, with major relevance to studies on detrital mineral suites, particularly those containing a record of early Earth redox conditions, and on the climatic impact of historic volcanic eruptions[2]. [1] Stephens, W. E., Whitley, J. E., Thirlwall, M. F. and Halliday, A. N. (1985) The Criffell zoned pluton: correlated behaviour of rare earth element abundances with isotopic systems. Contributions to Mineralogy and

  20. Cheating the CHA2DS2-VASc Score: Thromboembolism in Apical Hypertrophic Cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Robin A. P. Weir

    2014-01-01

    Full Text Available Atrial fibrillation increases the risk of systemic thromboembolism in general and stroke in particular. Not all patients who develop atrial fibrillation are at significantly heightened risk of thromboembolic complications, however, with the development of risk scoring systems aiding clinicians in determining whether formal anticoagulation is mandated. The most commonly used contemporary scoring systems—CHADS2 and CHA2DS2-VASc—provide a reliable means of assessing stroke risk, but certain cardiac conditions are associated with an increased incidence of thromboembolism without impacting on these risk scores. Hypertrophic cardiomyopathy, with its apical variant, is such a condition. We present a case of a patient with apical hypertrophic cardiomyopathy and atrial fibrillation who suffered dire thromboembolic consequences despite a reassuringly low CHA2DS2-VASc score and suggest that this scoring system is modified to incorporate the thromboembolic risk inherent to certain cardiomyopathies irrespective of impairment of left ventricular systolic dysfunction or clinical heart failure.

  1. Influe nce of senso f storag ory cha ge of r aracte refrige ristics rated ...

    African Journals Online (AJOL)

    SAM

    n yield and se. Fresh milk, s. N milk under ref e microbiolo of the raw mperatures, hic microorg oducts. It is e author. E-mail: that this article ense. August, 2014. 0. 540 ht of this article als.org/AJB h Paper f storag ory cha ...... em amostras de leite pasteurizado e UHT. Rev. Inst. Latic. “Cândido. Tostes”. 65:29-35. Schuster C ...

  2. Transformer les chaînes de valeur en avantages sociaux en Asie du ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les chaînes de valeur mondiales, qui constituent aujourd'hui la plus importante part du commerce mondial, se composent de producteurs et d'entreprises qui créent des biens comme entrants destinés à d'autres producteurs. Dans les pays d'Asie du SudEst, ces ... Agent(e) responsable du CRDI. Bouba Housseini ...

  3. Transformer les chaînes de valeur en avantages sociaux en Asie du ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les chaînes de valeur mondiales, qui constituent aujourd'hui la plus importante part du commerce mondial, se composent de producteurs et d'entreprises qui créent des biens comme entrants destinés à d'autres producteurs. Dans les pays d'Asie du SudEst, ces industries emploient de nombreux travailleurs peu ...

  4. Usefulness of the CHA2DS2-VASC Score to Predict Adverse Outcomes in Patients Having Percutaneous Coronary Intervention.

    Science.gov (United States)

    Orvin, Katia; Bental, Tamir; Assali, Abid; Lev, Eli Israel; Vaknin-Assa, Hana; Kornowski, Ran

    2016-05-01

    The application of the CHA2DS2-VASC score as a novel risk stratification tool for predicting outcome in clinical applications other than atrial fibrillation and stroke prevention has been previously examined. However, its usefulness in a population of patients with coronary artery disease after percutaneous coronary intervention (PCI) has not been explored. We investigated 12,785 consecutive patients who underwent PCI in a tertiary medical center from April 2004 to August 2014 (mean follow-up 6.5 years) and computed the CHA2DS2-VASC score on their index PCI. We assessed the relation between the CHA2DS2-VASC score and clinical outcomes (for example, all-cause mortality and mortality or myocardial infarction) at 1 and 5 years. The mean CHA2DS2-VASC score was 3.7 ± 1.7, 59.1% of patients obtained a score of 3 to 5. Both the primary and secondary outcomes at 1 and 5 years were significantly more frequent as the CHA2DS2-VASC score increased. Overall, the mortality rate after PCI was 10 times higher for patients with a CHA2DS2-VASC score of 5 compared with a score of 1 at both 1-and 5-year follow-up. The CHA2DS2-VASC score predicted all-cause mortality and death or nonfatal myocardial infarction in a significant (p <0.001, C-index 0.73 and 0.72) and linear fashion. In conclusion, the CHA2DS2-VASC score can be used as a simple and effective tool to predict long-term clinical outcomes in patients undergoing PCI. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Enrichment of Cross-Linked Peptides Using Charge-Based Fractional Diagonal Chromatography (ChaFRADIC).

    Science.gov (United States)

    Tinnefeld, Verena; Venne, A Saskia; Sickmann, Albert; Zahedi, René P

    2017-02-03

    Chemical cross-linking of proteins is an emerging field with huge potential for the structural investigation of proteins and protein complexes. Owing to the often relatively low yield of cross-linking products, their identification in complex samples benefits from enrichment procedures prior to mass spectrometry analysis. So far, this is mainly accomplished by using biotin moieties in specific cross-linkers or by applying strong cation exchange chromatography (SCX) for a relatively crude enrichment. We present a novel workflow to enrich cross-linked peptides by utilizing charge-based fractional diagonal chromatography (ChaFRADIC). On the basis of two-dimensional diagonal SCX separation, we could increase the number of identified cross-linked peptides for samples of different complexity: pure cross-linked BSA, cross-linked BSA spiked into a simple protein mixture, and cross-linked BSA spiked into a HeLa lysate. We also compared XL-ChaFRADIC with size exclusion chromatography-based enrichment of cross-linked peptides. The XL-ChaFRADIC approach is straightforward, reproducible, and independent of the cross-linking chemistry and cross-linker properties.

  6. Apatite as probe for the halogen composition of metamorphic fluids (Bamble Sector, SE Norway)

    Science.gov (United States)

    Kusebauch, Christof; John, Timm; Whitehouse, Martin J.; Engvik, Ane K.

    2015-10-01

    Halogen composition of replaced apatite formed during a regional metasomatic event (Bamble Sector, SE Norway) reveals information about the composition and evolution of the hydrothermal fluid. Infiltration and pervasive fluid flow of highly saline fluids into gabbroic bodies lead to scapolitization and amphibolitization, where magmatic Cl-rich apatite reacts with the hydrothermal fluid to form OH- and/or F-rich apatite. Apatite from highly altered samples adjacent to the shear zone has highest F (up to 15,000 µg/g) and lowest Br (4-25 µg/g) concentrations, whereas apatite from least altered samples has very low F (30-200 µg/g) and high Br (30-85 µg/g). In addition, individual replaced apatite grains show a zonation in F with high concentrations along rims and cracks and low F in core regions. Iodine concentrations remain rather constant as low values of 0.18-0.70 µg/g. We interpret all observed compositional features of replaced apatite to be the result of a continuous evolution of the fluid during fluid-rock interaction. Due to its high compatibility, F from the infiltrating fluid is incorporated early into recrystallized apatite (close to shear zone and rims of individual apatite grains). In contrast, Br as an incompatible halogen becomes enriched in the fluid and is highest in the most evolved fluid. Using experimental partition data between replaced apatite and fluid, we calculated F concentrations of the evolving fluid to decrease from 60 to 370 µg/g. Although Cl is expected to show a similar behavior as Br, replaced apatite has constant Cl concentrations throughout the alteration sequence (~1 wt.%), which is likely the result of a rather constant Cl activity in the fluid. Chlorine stable isotope values of individual apatite grains are heterogeneous and range from -1.2 to +3.7 ‰. High δ 37Cl values are generally correlated with OH-rich zones of replaced apatite, whereas low δ 37Cl values are measured in F-rich zones of replaced apatite and in Cl-apatite

  7. Thermodynamic Mixing Behavior Of F-OH Apatite Crystalline Solutions

    Science.gov (United States)

    Hovis, G. L.

    2011-12-01

    It is important to establish a thermodynamic data base for accessory minerals and mineral series that are useful in determining fluid composition during petrologic processes. As a starting point for apatite-system thermodynamics, Hovis and Harlov (2010, American Mineralogist 95, 946-952) reported enthalpies of mixing for a F-Cl apatite series. Harlov synthesized all such crystalline solutions at the GFZ-Potsdam using a slow-cooled molten-flux method. In order to expand thermodynamic characterization of the F-Cl-OH apatite system, a new study has been initiated along the F-OH apatite binary. Synthesis of this new series made use of National Institute of Standards and Technology (NIST) 2910a hydroxylapatite, a standard reference material made at NIST "by solution reaction of calcium hydroxide with phosphoric acid." Synthesis efforts at Lafayette College have been successful in producing fluorapatite through ion exchange between hydroxylapatite 2910a and fluorite. In these experiments, a thin layer of hydroxylapatite powder was placed on a polished CaF2 disc (obtained from a supplier of high-purity crystals for spectroscopy), pressed firmly against the disc, then annealed at 750 °C (1 bar) for three days. Longer annealing times did not produce further change in unit-cell dimensions of the resulting fluorapatite, but it is uncertain at this time whether this procedure produces a pure-F end member (chemical analyses to be performed in the near future). It is clear from the unit-cell dimensions, however, that the newly synthesized apatite contains a high percentage of fluorine, probably greater than 90 mol % F. Intermediate compositions for a F-OH apatite series were made by combining 2910a hydroxylapatite powder with the newly synthesized fluorapatite in various proportions, then conducting chemical homogenization experiments at 750 °C on each mixture. X-ray powder diffraction data indicated that these experiments were successful in producing chemically homogeneous

  8. Apatite: a new redox proxy for silicic magmas?

    OpenAIRE

    Miles, A.J.; Graham, C M; Hawkesworth, C.J.; Gillespie, M.R.; Hinton, R.W.; Bromiley, G.D.

    2014-01-01

    The oxidation states of magmas provide valuable information about the release and speciation of volatile elements during volcanic eruptions, metallogenesis, source rock compositions, open system magmatic processes, tectonic settings and potentially titanium (Ti) activity in chemical systems used for Ti-dependent geothermometers and geobarometers. In this paper we explore the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks. Increased Mn concentrations in apati...

  9. Improving the apatite fission-track annealing algorithm

    Science.gov (United States)

    Luijendijk, Elco; Andriessen, Paul; ter Voorde, Marlies; van Balen, Ronald

    2017-04-01

    Low-temperature thermochronology is a key tool to quantifying the thermal history and exhumation of the crust. The interpretation of one of the most widely-used thermochronometers, apatite fission-track analysis, relies on models that relate fission track density to temperature history. These models have been calibrated to fission-track data from the Otway basin, Australia. We discuss geological evidence that the current benchmark dataset is located in a basin in which rocks may have been warmer in the past than previously assumed. We recalibrate the apatite fission-track annealing algorithm to a dataset from Southern Texas with a well-constrained thermal history. We show that current models underestimate the temperature at which fission tracks anneal completely by 19 ˚C to 34 ˚C. Exhumation rates derived from fission-track data have been underestimated; at normal geothermal gradients estimates may have to be revised upward by 500 to 2000 m. The results also have implications for the (U-Th)/He thermochronometer, because radiation damage influences the diffusivity of helium in apatites. The difference in modelled (U-Th)/He ages is approximately 10% for samples that have undergone a long cooling history. We also present a new Python code that can be used for forward or inverse modelling of fission track data using the new annealing algorithm.

  10. Annealing behaviour of ion tracks in olivine, apatite and britholite

    Energy Technology Data Exchange (ETDEWEB)

    Afra, B. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Lang, M. [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Bierschenk, T.; Rodriguez, M.D. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Weber, W.J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, TN (United States); Trautmann, C. [GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt (Germany); Technische Universität Darmstadt, 64289 Darmstadt (Germany); Ewing, R.C. [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Kirby, N. [Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168 (Australia); Kluth, P., E-mail: patrick.kluth@anu.edu.au [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)

    2014-05-01

    Ion tracks were created in olivine from San Carlos, Arizona (95% Mg{sub 2}SiO{sub 4}), apatite (Ca{sub 5}(PO4){sub 3}(F,Cl,O)) from Durango, Mexico, and synthetic silicates with the apatite structure: Nd{sub 8}Sr{sub 2}(SiO{sub 4}){sub 6}O{sub 2} and Nd{sub 8}Ca{sub 2}(SiO{sub 4}){sub 6}O{sub 2} using 1.6 and 2.2 GeV Au ions. The morphology and annealing behaviour of the tracks were investigated by means of synchrotron based small angle X-ray scattering in combination with ex situ annealing. Tracks in olivine annealed above ∼400 °C undergo a significant change in track radius due to recrystallisation of the damage tracks. At temperatures higher than 620 °C, the scattering images indicate fragmentation of the track cylinders into smaller subsections. Ion tracks were annealed at elevated temperatures up to 400 °C in the Durango and Ca-britholite, and up to 560 °C in Sr-britholite. While there was a significant change in the track radii in the Durango apatite, tracks in the two synthetic samples remained almost unchanged.

  11. Influence of agitation intensity on flotation rate of apatite particles

    Directory of Open Access Journals (Sweden)

    Francisco Gregianin Testa

    Full Text Available Abstract The agitation intensity has a directly influence on flotation performance, lifting the particles and promoting the contact of bubbles and particles. In this paper, the energy input by the agitation on apatite flotation was investigated. The influence of pulp agitation in the flotation rate of particles with different sizes and two dosage levels was evaluated by batch testing. The flotation tests were conducted in an oscillating grid flotation cell (OGC, developed to promote a near isotropic turbulence environment. The cell is able to control the intensity of agitation and measure the energy transferred to the pulp phase. A sample of pure apatite was crushed (P80=310µm, characterized and floated with sodium oleate as collector. Four levels of energy dissipation, from 0.1 to 2 kWm-3, and two levels of collector dosage are used during the tests. The flotation kinetics by particle size were determined in function of the energy transferred. The results show a strong influence of the agitation intensity on the apatite flotation rate with both low and high dosage. For fine particles, when increasing the energy input, the flotation rate increase too, and this fact can be attributed to elevation of bubble-particle collisions. The kinetic result for the coarse particles demonstrated a reduction of the flotation rate whenever the energy input for this particle size was increased, whereby the turbulence caused by the agitation promotes the detachment of bubble-particle.

  12. Experimental Constraints on the Partitioning Behavior of F, Cl, and OH Between Apatite and Basaltic Melt

    Science.gov (United States)

    McCubbin, Francis M.; Barnes, Jessica J.; Vander Kaaden, Kathleen E.; Boyce, Jeremy W.; Ustunisik, Gokce; Whitson, Eric S.

    2017-01-01

    The mineral apatite is present in a wide range of planetary materials. The presence of volatiles (F, Cl, and OH) within its crystal structure (X-site) have motivated numerous studies to investigate the partitioning behavior of F, Cl, and OH between apatite and silicate melt with the end goal of using apatite to constrain the volatile contents of planetary magmas and mantle sources. A number of recent experimental studies have investigated the apatite-melt partitioning behavior of F, Cl, and OH in magmatic systems. Apatite-melt partitioning of volatiles are best described as exchange equilibria similar to Fe-Mg partitioning between olivine and silicate melt. However, the partitioning behavior is likely to change as a function of temperature, pressure, oxygen fugacity, apatite composition, and melt composition. In the present study, we have conducted experiments to assess the partitioning behavior of F, Cl, and OH between apatite and silicate melt over a pressure range of 0-6 gigapascals, a temperature range of 950-1500 degrees Centigrade, and a wide range of apatite ternary compositions. All of the experiments were conducted between iron-wustite oxidation potentials IW minus 1 and IW plus 2 in a basaltic melt composition. The experimental run products were analyzed by a combination of electron probe microanalysis and secondary ion mass spectrometry (NanoSIMS). Temperature, apatite crystal chemistry, and pressure all play important roles in the partitioning behavior of F, Cl, and OH between apatite and silicate melt. In portions of apatite ternary space that undergo ideal mixing of F, Cl, and OH, exchange coefficients remain constant at constant temperature and pressure. However, exchange coefficients vary at constant temperature (T) and pressure (P) in portions of apatite compositional space where F, Cl, and OH do not mix ideally in apatite. The variation in exchange coefficients exhibited by apatite that does not undergo ideal mixing far exceeds the variations

  13. Electron-induced processes in hydroxyl cations

    Science.gov (United States)

    Cristian Stroe, Marius; Fifirig, Magda

    2018-01-01

    Competing processes (namely, dissociative recombination, vibrational excitation and vibrational de-excitation) taking place in the collisions between slow electrons and hydroxyl cations have been investigated for electron energies below 1 eV in the framework of the multichannel quantum defect theory. Rydberg states converging to the lowest excited ionic core have been included in some computations reported here.

  14. New Directions: Watching over tropospheric hydroxyl (OH)

    NARCIS (Netherlands)

    Lelieveld, J.|info:eu-repo/dai/nl/411295810; Brenninkmeijer, C.A.M.; Joeckel, P.; Isaksen, I.S.A.; Krol, M.C.|info:eu-repo/dai/nl/078760410; Mak, J.E.; Dlugokencky, E.; Montzka, S.A.; Novelli, P.C.; Peters, W.; Tans, P.P.

    2006-01-01

    Mean tropospheric hydroxyl radical (OH) abundance is often used as a measure of the oxidation capacity (or “self-cleansing”) of the atmosphere. The primary mechanism by which atmospheric pollutant gases are removed from the atmosphere is initiated by the reaction with OH. As a result, large

  15. Hydroxyl radical formation in human gastric juice.

    Science.gov (United States)

    Nalini, S; Ramakrishna, B S; Mohanty, A; Balasubramanian, K A

    1992-01-01

    The hydroxyl radical is the most potent free radical derived from oxygen, and has been implicated in damage caused to the gastroduodenal mucosa. The ability of human gastric juice to generate hydroxyl radicals has been investigated in 54 adults with endoscopically normal gastroduodenal mucosa and in 39 patients with chronic duodenal ulcer. Hydroxyl radical production was measured by the formation of formaldehyde from dimethylsulfoxide. Unlike other body fluids, this reaction could proceed without the extraneous addition of catalysts such as hydrogen peroxide (H2O2), ascorbate and iron. Measurement of H2O2, iron and ascorbate showed that these catalysts are already present in the gastric juice. There was no significant difference in the concentration of these components in gastric juice between normal subjects and patients with duodenal ulcer, except that H2O2 levels were slightly higher in duodenal ulcer patients. Although generation of free radicals has been investigated in other body fluids, this is the first reported case regarding the production of these active species in normal human gastric juice. Since hydroxyl production is not significantly enhanced in duodenal ulcer, we suggest that attention may be turned to mucosal antioxidant defences in this disease.

  16. Bacterial formation of hydroxylated aromatic compounds

    NARCIS (Netherlands)

    Tweel, van den W.J.J.

    1988-01-01

    As stated in the introduction of this thesis, hydroxylated aromatic compounds in general are of great importance for various industries as for instance pharmaceutical, agrochemical and petrochemical industries. Since these compounds can not be isolated in sufficient amounts from natural

  17. Usefulness of the CHA2DS2-VASc Score to Predict Outcome in Patients Who Underwent Transcatheter Aortic Valve Implantation.

    Science.gov (United States)

    Orvin, Katia; Levi, Amos; Landes, Uri; Bental, Tamir; Sagie, Alexander; Shapira, Yaron; Vaknin-Assa, Hana; Assali, Abid; Kornowski, Ran

    2017-10-19

    Risk assessment for transcatheter aortic valve implantation (TAVI) patients remains challenging, especially in elderly and high-risk candidates. Although several risk factors contribute to increased morbidity and mortality after TAVI, simple risk scores for routine use are lacking. Applying the CHA2DS2-VASC (congestive heart failure, hypertension, age ≥ 75 years, diabetes, prior stroke, vascular disease, age 65-74 years, sex [female] category) score as a novel risk stratification tool for conditions other than atrial fibrillation and stroke prevention has been previously examined; however, its usefulness in a population of patients with aortic stenosis after TAVI has not been established. Thus, we investigated 633 consecutive patients who underwent TAVI between November 2008 and May 2017, and calculated the CHA2DS2-VASC score. Patients were stratified according to their CHA2DS2-VASC score into 3 categories (0 to 3, 4 to 6, 7 to 9), and the association between CHA2DS2-VASC score and 1-year clinical outcomes (stroke, all-cause mortality, and combined outcome of stroke or mortality) was evaluated. We found that both stroke and mortality at 1 year were significantly more frequent with increasing CHA2DS2-VASC score (p = 0.012 and p = 0.025, respectively). Each single-point rise in CHA2DS2-VASC score was associated with a 38% increase in the 1-year combined outcome of mortality or stroke (p = 0.022; C index 0.615). In conclusion, CHA2DS2-VASC score can be used as a simple and effective tool to predict 1-year clinical outcomes including death and stroke in patients who underwent TAVI. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    OpenAIRE

    Jianwei eWang

    2015-01-01

    Materials with apatite crystal structure have 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 (A5(XO4)3Z) was investigated for iodide incorporation into the channel of the structure using Artificial Neural Networ...

  19. Coprecipitation of DNA-lipid complexes with apatite and comparison with superficial adsorption for gene transfer applications.

    Science.gov (United States)

    Yazaki, Yushin; Oyane, Ayako; Tsurushima, Hideo; Araki, Hiroko; Sogo, Yu; Ito, Atsuo; Yamazaki, Atsushi

    2014-02-01

    Apatite can mediate gene transfer into cells by serving as a safe and biocompatible immobilization matrix for DNA and transfection reagents. Recently, an apatite layer that immobilized DNA-lipid complexes was prepared by a coprecipitation process in a supersaturated calcium phosphate solution. This composite layer (DNA-lipid-apatite layer) showed a higher gene transfer capability than an apatite layer with superficially adsorbed DNA-lipid complexes (DNA-lipid-adsorbed apatite layer). In this study, the DNA-lipid-apatite layer and the DNA-lipid-adsorbed apatite layer were compared for their physicochemical properties and gene transfer capabilities. The higher gene transfer capability of the DNA-lipid-apatite layer compared with that of the DNA-lipid-adsorbed apatite layer was reconfirmed by a luciferase assay using epithelial-like CHO-K1 cells. Physicochemical structure analyses showed that the DNA-lipid-apatite layer possessed a larger capacity for DNA-lipid complexes than the DNA-lipid-adsorbed apatite layer. The DNA-lipid-apatite layer released DNA-lipid complexes in a slow and sustained manner, whereas the DNA-lipid-adsorbed apatite layer released them in short bursts. Consequently, the release of DNA-lipid complexes from the DNA-lipid-apatite layer was larger in amount and longer in duration than release from the DNA-lipid-adsorbed apatite layer. This difference in release profiles may be responsible for the higher gene transfer capability of the DNA-lipid-apatite layer compared with that of the DNA-lipid-adsorbed apatite layer. The coprecipitation process and the resulting DNA-lipid-apatite layer have many applications in tissue engineering.

  20. 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.

  1. Intragranular replacement of chlorapatite by hydroxy-fluor-apatite during metasomatism

    Science.gov (United States)

    Engvik, Ane K.; Golla-Schindler, Ute; Berndt, Jasper; Austrheim, Håkon; Putnis, Andrew

    2009-10-01

    The pseudomorphic replacement of chlorapatite by hydroxy-fluor-apatite is associated with metasomatism of the Ødegården metagabbro (Bamble, south Norway). Primary fluor-chlorapatite in the protolith gabbro is non-porous and homogenous in composition with F-content of up to 3.5 wt% and Cl-content up to 2 wt.%. Metasomatism transforms apatite during multi-stage replacement reactions: I) Magmatic apatite was transformed to chlorapatite with Cl-content of up to 6.8 wt.% during scapolitisation. II) A secondary pseudomorphic replacement reaction which transforms chlorapatite to porous hydroxy-fluor-apatite with only minor Cl is related to albitisation. Laser ablation inductively coupled mass spectrometry (LA ICPMS) data from the primary fluor-chlorapatite shows in general a high content of Sr, Y, REE and Th. Chlor- and hydroxy-fluor-apatite show depletion in Co, Ni, Sr, Cd, Pb, Th and U, and enrichment in V and Ba, relative to the primary apatite. The replacement interface of chlorapatite to hydroxy-fluor-apatite is studied by energy-filtered transmission electron microscopy (TEM). The interface is sharp on a nano-scale, and the crystallographic orientation of the apatite is preserved. These observations, together with the porosity development in the hydroxy-fluor-apatite suggest that the replacement mechanism is by interface-coupled dissolution-reprecipitation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kuczumow, A., E-mail: kuczon@kul.lublin.pl [Department of Chemistry, Lublin Catholic University, 20-718 Lublin (Poland); Nowak, J. [Department of Chemistry, Lublin Catholic University, 20-718 Lublin (Poland); ChaLas, R. [Department of Conservative Medicine, Lublin Medical University, 20-081 Lublin (Poland)

    2011-10-15

    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 ({approx}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 CO{sub 3}{sup 2-} 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 CO{sub 3}{sup 2-}. 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

  3. 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)

  4. H-Isotopic Composition of Apatite in Northwest Africa 7034

    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 estimates of Mars' bulk crust composition [1]. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the crustal composition of components that cannot be measured directly by remote sensing. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034.

  5. Developing biogeochemical tracers of apatite weathering by ectomycorrhizal fungi

    Science.gov (United States)

    Vadeboncoeur, M. A.; Bryce, J. G.; Hobbie, E. A.; Meana-Prado, M. F.; Blichert-Toft, J.

    2012-12-01

    Chronic acid deposition has depleted calcium (Ca) from many New England forest soils, and intensive harvesting may reduce phosphorus (P) available to future rotations. Thin glacial till soils contain trace amounts of apatite, a primary calcium phosphate mineral, which may be an important long-term source of both P and Ca to ecosystems. The extent to which ECM fungi enhance the weathering rate of primary minerals in soil which contain growth-limiting nutrients remains poorly quantified, in part due to biogeochemical tracers which are subsequently masked by within-plant fractionation. Rare earth elements (REEs) and Pb isotope ratios show some potential for revealing differences in soil apatite weathering rates across forest stands and silvicultural treatments. To test the utility of these tracers, we grew birch seedlings semi-hydroponically under controlled P-limited conditions, supplemented with mesh bags containing granite chips. Our experimental design included nonmycorrhizal (NM) as well as ectomycorrhizal cultures (Cortinarius or Leccinum). Resulting mycorrhizal roots and leachates of granite chips were analyzed for these tracers. REE concentrations in roots were greatly elevated in treatments with granite relative to those without granite, demonstrating uptake of apatite weathering products. Roots with different mycorrhizal fungi accumulated similar concentrations of REEs and were generally elevated compared to the NM cultures. Ammonium chloride leaches of granite chips grown in contact with mycorrhizal hyphae show elevated REE concentrations and significantly radiogenic Pb isotope signatures relative to bulk rock, also supporting enhanced apatite dissolution. Our results in culture are consistent with data from field-collected sporocarps from hardwood stands in the Bartlett Experimental Forest in New Hampshire, in which Cortinarius sporocarp Pb isotope ratios were more radiogenic than those of other ectomycorrhizal sporocarps. Taken together, the experimental

  6. Ambi-site substitution of Mn in Lanthanum Germanate Apatites

    OpenAIRE

    E. Kendrick; Knight, K. S.; Slater, P. R.

    2009-01-01

    A neutron diffraction study at 4K of the Mn doped lanthanum germanate apatite-type oxide ion conductor of nominal starting composition “La9.5Mn0.5(GeO4)6O2.75” is reported. The structure was refined in space group P63/m, although high thermal displacement parameters were observed for the oxide ion sites (particularly O3, and O4). Reduced thermal displacement parameters were obtained by splitting the O3 site, and allowing the O4 oxygen to move off site, which may indicate local regions of lowe...

  7. Light-driven cytochrome P450 hydroxylations

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Jensen, Poul Erik; Møller, Birger Lindberg

    2011-01-01

    Plants are light-driven "green" factories able to synthesize more than 200,000 different bioactive natural products, many of which are high-value products used as drugs (e.g., artemisinin, taxol, and thapsigargin). In the formation of natural products, cytochrome P450 (P450) monooxygenases play...... a key role in catalyzing regio- and stereospecific hydroxylations that are often difficult to achieve using the approaches of chemical synthesis. P450-catalyzed monooxygenations are dependent on electron donation typically from NADPH catalyzed by NADPH-cytochrome P450 oxidoreductase (CPR......). The consumption of the costly cofactor NADPH constitutes an economical obstacle for biotechnological in vitro applications of P450s. This bottleneck has been overcome by the design of an in vitro system able to carry out light-driven P450 hydroxylations using photosystem I (PSI) for light harvesting...

  8. Hydroxyl radical induced degradation of ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Illés, Erzsébet, E-mail: erzsebet.illes@chem.u-szeged.hu [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Takács, Erzsébet [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Dombi, András [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Gajda-Schrantz, Krisztina [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged (Hungary); EMPA, Laboratory for High Performance Ceramics, Duebendorf (Switzerland); Rácz, Gergely; Gonter, Katalin; Wojnárovits, László [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary)

    2013-03-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm{sup −3}. For end product characterization {sup 60}Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of {sup ·}OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation.

  9. CHA2DS2-VASc score and exercise capacity of patients with coronary artery disease participating in cardiac rehabilitation programs.

    Science.gov (United States)

    Haskiah, Feras; Shacham, Yacov; Minha, Saar; Rozenbaum, Zach; Pereg, David

    2017-12-01

    Exercise based cardiac rehabilitation improves prognosis and quality of life in patients with coronary artery disease. We aimed to investigate whether the CHA2DS2-VASc score may be a predictor of improvement in exercise capacity in acute coronary syndrome (ACS) patients participating in a cardiac rehabilitation program. Included were patients following a hospital admission due to ACS and were subsequently referred for an exercise based cardiac rehabilitation during 2010-2015. Participants were divided into three groups of low (1-2), intermediate (3) and high (4≤) CHA2DS2-VASc score. Exercise capacity was evaluated by a treadmill stress test at baseline and following 9 months. The primary endpoint was the percent of patients who achieved at least 25% improvement in exercise capacity. The 597 patients included in the study had a mean age of 65.5±9.3 years and consisted of 22.5% women. The primary endpoint of at least 25% improvement in exercise capacity following 9 months of cardiac rehabilitation occurred more frequently in patients in the high CHA2DS2-VASc group compared to the intermediate and low CHA2DS2-VASc score groups (47.3, 29.9 and 36.1% in the high, intermediate and low CHA2DS2-VASc score groups respectively, P=0.002). The CHA2DS2-VASc score may serve as a predictor of exercise capacity improvement. Its use for tailoring specific cardiac rehabilitation programs for ACS patients may yield further improvement in functional capacity and better utilization of resources.

  10. A gacS deletion in Pseudomonas aeruginosa cystic fibrosis isolate CHA shapes its virulence.

    Directory of Open Access Journals (Sweden)

    Khady Mayebine Sall

    Full Text Available Pseudomonas aeruginosa, a human opportunistic pathogen, is capable of provoking acute and chronic infections that are associated with defined sets of virulence factors. During chronic infections, the bacterium accumulates mutations that silence some and activate other genes. Here we show that the cystic fibrosis isolate CHA exhibits a unique virulence phenotype featuring a mucoid morphology, an active Type III Secretion System (T3SS, hallmark of acute infections, and no Type VI Secretion System (H1-T6SS. This virulence profile is due to a 426 bp deletion in the 3' end of the gacS gene encoding an essential regulatory protein. The absence of GacS disturbs the Gac/Rsm pathway leading to depletion of the small regulatory RNAs RsmY/RsmZ and, in consequence, to expression of T3SS, while switching off the expression of H1-T6SS and Pel polysaccharides. The CHA isolate also exhibits full ability to swim and twitch, due to active flagellum and Type IVa pili. Thus, unlike the classical scheme of balance between virulence factors, clinical strains may adapt to a local niche by expressing both alginate exopolysaccharide, a hallmark of membrane stress that protects from antibiotic action, host defences and phagocytosis, and efficient T3S machinery that is considered as an aggressive virulence factor.

  11. Heterotopic bone formation by nano-apatite containing poly (D,L-lactide) composites

    NARCIS (Netherlands)

    Barbieri, D.; Barbieri, D.; Renard, A.J.S.; de Bruijn, Joost Dick; Yuan, Huipin

    2010-01-01

    To render polymeric materials osteoinductive, nano-sized calcium phosphate apatite particles (CaP) were introduced into a low molecular weight poly(D,L-lactide). Homogenous composites were made with 10%, 20% and 40% by weight of apatite content while pure polylactide was used as control. Thereafter

  12. 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.

  13. Lepidocrocite, an apatite mineral, and magnetic in teeth of chitons (Polyplacophora).

    Science.gov (United States)

    Lowenstam, H A

    1967-06-09

    X-ray diffraction patterns show that the mature denticles of three extant chiton species are composed of the mineral lepidocrocite and an apatite mineral, probably francolite, in addition to magnetite. Each of the three minerals forms a discrete microarchitectural unit of the chiton denticles. This is the first indication that lepidocrocite is precipitated by marine organisms and an apatite mineral by chitons.

  14. Crystallinity control of apatite through Ca-EDTA complexes and porous composites with PLGA.

    Science.gov (United States)

    Mochizuki, Chihiro; Sasaki, Yuji; Hara, Hiroki; Sato, Mitsunobu; Hayakawa, Tohru; Yang, Fei; Hu, Xixue; Shen, Hong; Wang, Shenguo

    2009-07-01

    Apatite compounds with different levels of crystallinity were prepared using Ca-EDTA complexes. Ca-deficient hydroxyapatite (CDHA) with low crystallinity was synthesized by ultrasonic stirring of a mixture of Ca-EDTA complex, phosphoric acid, and ammonium hydroxide in hydrogen peroxide aqueous solution. Mixtures of carbonate hydroxyapatite (HA) and CDHA with higher crystallinity were also prepared from a solution involving the same complex. The porous composites with lower or higher crystallinity apatite with a copolymer of poly(L-lactide-co-glycilide)(70/30) (PLGA(70/30)) were fabricated by a solution-casting/particles leaching method. The apatites and porous composites were characterized, and it was found that the degradation of composites of apatite with a low level of crystallinity was fastest in phosphate-bufferd saline (PBS) solution compared with other apatite composites with higher levels of crystallinity; however, the rate was smaller than that of PLGA alone. Plasma treatment influenced the degradation of composites in PBS and apatite precipitation in simulated body fluid (SBF). Hydroxyapatite deposition on the PLGA composite with the low crystallinity occurred six times faster than that on PLGA alone after immersion in SBF. The incorporation of apatite into the PLGA matrix did not cause any adverse effects on cell attachment in an assay employing human gingival fibroblasts. This study suggested that the current apatite and PLGA porous composite will be a promising scaffold material for tissue engineering. (c) 2008 Wiley Periodicals, Inc.

  15. Ionic Substitutions in Non-Apatitic Calcium Phosphates

    Science.gov (United States)

    Laskus, Aleksandra; Kolmas, Joanna

    2017-01-01

    Calcium phosphate materials (CaPs) are similar to inorganic part of human mineralized tissues (i.e., bone, enamel, and dentin). Owing to their high biocompatibility, CaPs, mainly hydroxyapatite (HA), have been investigated for their use in various medical applications. One of the most widely used ways to improve the biological and physicochemical properties of HA is ionic substitution with trace ions. Recent developments in bioceramics have already demonstrated that introducing foreign ions is also possible in other CaPs, such as tricalcium phosphates (amorphous as well as α and β crystalline forms) and brushite. The purpose of this paper is to review recent achievements in the field of non-apatitic CaPs substituted with various ions. Particular attention will be focused on tricalcium phosphates (TCP) and “additives” such as magnesium, zinc, strontium, and silicate ions, all of which have been widely investigated thanks to their important biological role. This review also highlights some of the potential biomedical applications of non-apatitic substituted CaPs. PMID:29186932

  16. TREATMENT OF ACID MINE DRAINAGE USING FISHBONE APATITE IITM

    Energy Technology Data Exchange (ETDEWEB)

    Neal A. Yancey

    2006-10-01

    ABSTRACT. In 2000, a reactive barrier was installed on the East Fork of Ninemile Creek near Wallace, Idaho to treat acid mine discharge. The barrier was filled with fishbone derived Apatite IITM to remove the contaminants of concern (Zn, Pb, and Cd) and raise the pH of the acidic mine discharge. Metal removal has been achieved by a combination of chemical, biological, and physical precipitation. Flow for the water ranges from 5 to 35 gallons per minute. The water is successfully being treated, but the system experienced varying degrees of plugging. In 2002, gravel was mixed with the Apatite IITM to help control plugging. In 2003 the Idaho National Laboratory was ask to provide technical support to the Coeur d’Alene Basin Commission to help identify a remedy to the plugging issue. Air sparging was employed to treat the plugging issues. Plastic packing rings were added in the fall of 2005, which have increased the void space in the media and increased flows during the 10 months of operation since the improvements were made.

  17. Crystal growth of apatite by replacement of an aragonite precursor

    Science.gov (United States)

    Kasioptas, Argyrios; Geisler, Thorsten; Putnis, Christine V.; Perdikouri, Christina; Putnis, Andrew

    2010-08-01

    The replacement of aragonite by apatite is a process that occurs naturally during diagenesis, chemical weathering and natural hydrothermal reactions and is artificially promoted in medical sciences for use of the product material as a bone implant. We have investigated the mechanism and the kinetics of this replacement by using biogenic aragonite (cuttlebone of the Sepia officinalis) as a starting material and reacting it with di-ammonium hydrogen phosphate solution. Isothermal experiments were carried out over a range of temperatures up to 190 °C. Quantification of each solid phase, for different reaction times, was obtained by the Rietveld analysis of powder X-ray diffraction patterns. An empirical activation energy was calculated by using two different approaches to analyze the data. Scanning electron microscopy showed that the fine structure of the cuttlebone was perfectly retained even after aragonite had been completely converted to apatite. We present a detailed investigation of the kinetics of a reaction that involves interaction of a solid phase with an aqueous fluid and leads to a pseudomorphic replacement of the initial solid phase by a new, chemically different, phase. This replacement process is described in terms of an interface-coupled dissolution-reprecipitation mechanism.

  18. Ionic Substitutions in Non-Apatitic Calcium Phosphates

    Directory of Open Access Journals (Sweden)

    Aleksandra Laskus

    2017-11-01

    Full Text Available Calcium phosphate materials (CaPs are similar to inorganic part of human mineralized tissues (i.e., bone, enamel, and dentin. Owing to their high biocompatibility, CaPs, mainly hydroxyapatite (HA, have been investigated for their use in various medical applications. One of the most widely used ways to improve the biological and physicochemical properties of HA is ionic substitution with trace ions. Recent developments in bioceramics have already demonstrated that introducing foreign ions is also possible in other CaPs, such as tricalcium phosphates (amorphous as well as α and β crystalline forms and brushite. The purpose of this paper is to review recent achievements in the field of non-apatitic CaPs substituted with various ions. Particular attention will be focused on tricalcium phosphates (TCP and “additives” such as magnesium, zinc, strontium, and silicate ions, all of which have been widely investigated thanks to their important biological role. This review also highlights some of the potential biomedical applications of non-apatitic substituted CaPs.

  19. 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

    OpenAIRE

    Mohammad Ali Rajabzadeh; Kiamars Hoseini; Zohreh Moosavinasab

    2014-01-01

    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 ...

  20. Extracellular Protease of Pseudomonas fluorescens CHA0, a Biocontrol Factor with Activity against the Root-Knot Nematode Meloidogyne incognita

    OpenAIRE

    Siddiqui, Imran Ali; Haas, Dieter; Heeb, Stephan

    2005-01-01

    In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocon...

  1. VizieR Online Data Catalog: Galactic CHaMP. III. 12CO dense clump properties (Barnes+,

    Science.gov (United States)

    Barnes, P. J.; Hernandez, A. K.; O'Dougherty, S. N.; Schap, W. J., III; Muller, E.

    2017-01-01

    In Phase II of the Mopra observing for the Census of High- and Medium-mass Protostars (CHaMP) project during 2009-12, we tuned the receiver to a central frequency of 111.3GHz and set up the Mopra Spectrometer (MOPS) digital filterbank to map all the CHaMP clumps in a second set of spectral lines at frequencies of 107-115GHz. This new set of transitions most notably includes the J=1->0 lines for the triad of CO-isotopologue species, 12CO, 13CO, and C18O. (3 data files).

  2. Assessment of left atrium mechanical function by deformation imaging in atrial fibrillation and its correlation with CHA2DS2-VASc risk score

    Directory of Open Access Journals (Sweden)

    Mahmoud Kamel Ahmed

    2015-09-01

    Conclusion: AF leads to impairment of LA mechanical function as evidenced by low PALS but PALS was not significantly correlated with CHA2DS2-VASc score. Also, there was no significantly statistical difference between PALS in patients with low and high CHA2DS2-VASc scores.

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

    Science.gov (United States)

    Wang, Jianwei

    2015-06-01

    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 procedure.

  4. Synthesis and Structural Characterization of a CHA-type AlPO4 Molecular Sieve with Penta-Coordinated Framework Aluminum Atoms.

    Science.gov (United States)

    Park, Gi Tae; Jo, Donghui; Ahn, Nak Ho; Cho, Jung; Hong, Suk Bong

    2017-07-17

    The structure-directing effects of a series of polymethylimidazolium cations with different numbers of methyl groups as organic structure-directing agents (OSDAs) in the synthesis of aluminophosphate (AlPO4)-based molecular sieves in both fluoride and hydroxide media are investigated. On the one hand, among the OSDAs studied here, the smallest 1,3-dimethylimidazolium and the largest 1,2,3,4,5-pentamethylimidazolium cations were found to direct the synthesis of a new variant of the triclinic chabazite (CHA)-type AlPO4 material, designated AlPO4-34(t)(V), and the one-dimensional small-pore silicoaluminophosphate (SAPO) molecular sieve STA-6 in hydroxide media, respectively. On the other hand, the intermediate-sized 1,2,3,4-tetramethylimidazolium cation gave SSZ-51, a two-dimensional large-pore SAPO material, in fluoride media. Synchrotron powder X-ray diffraction and Rietveld analyses reveal that as-made AlPO4-34(t)(V) contains penta-coordinated framework Al species connected by hydroxyl groups, as well as tetrahedral framework Al, which contrasts with the distortions arising from the two F(-) or OH(-) bridges between octahedral Al atoms in all already known AlPO4-34 materials. The presence of Al-OH-Al linkages in this triclinic AlPO4-34 molecular sieve has been further corroborated by thermal analysis, variable-temperature IR,27Al magic-angle spinning NMR, and dispersion-corrected density functional theory calculations.

  5. Effects of the method of apatite seed crystals addition on setting reaction of α-tricalcium phosphate based apatite cement.

    Science.gov (United States)

    Tsuru, Kanji; Ruslin; Maruta, Michito; Matsuya, Shigeki; Ishikawa, Kunio

    2015-10-01

    Appropriate setting time is an important parameter that determines the effectiveness of apatite cement (AC) for clinical application, given the issues of crystalline inflammatory response phenomena if AC fails to set. To this end, the present study analyzes the effects of the method of apatite seed crystals addition on the setting reaction of α-tricalcium phosphate (α-TCP) based AC. Two ACs, both consisting of α-TCP and calcium deficient hydroxyapatite (cdHAp), were analyzed in this study. In one AC, cdHAp was added externally to α-TCP and this AC was abbreviated as AC(EA). In the other AC, α-TCP was partially hydrolyzed to form cdHAp on the surface of α-TCP. This AC was referred to as AC(PH). Results indicate a decrease in the setting time of both ACs with the addition of cdHAp. Among them, for the given amount of added cdHAp, AC(PH) showed relatively shorter setting time than AC(EA). Besides, the mechanical strength of the set AC(PH) was also higher than that of set AC(EA). These properties of AC(PH) were attributed to the predominant crystal growth of cdHAp in the vicinity of the α-TCP particle surface. Accordingly, it can be concluded that the partial hydrolysis of α-TCP may be a better approach to add low crystalline cdHAp onto α-TCP based AC.

  6. The value of the CHA2DS2-VASc score for refining stroke risk stratification in patients with atrial fibrillation with a CHADS2 score 0-1

    DEFF Research Database (Denmark)

    Olesen, Jonas Bjerring; Torp-Pedersen, Christian; Hansen, Morten Lock

    2012-01-01

    associated with increasing CHA2DS2-VASc score was estimated in Cox regression models adjusted for year of inclusion and antiplatelet therapy. The value of adding the extra CHA2DS2-VASc risk factors to the CHADS2 score was evaluated by c-statistics, Net Reclassification Improvement (NRI) and Integrated......DS2-VASc score significantly improved the predictive value of the CHADS2 score alone and a CHA2DS2-VASc score=0 could clearly identify 'truly low risk' subjects. Use of the CHA2DS2-VASc score would significantly improve classification of AF patients at low and intermediate risk of stroke, compared......North American and European guidelines on atrial fibrillation (AF) are conflicting regarding the classification of patients at low/intermediate risk of stroke. We aimed to investigate if the CHA2DS2-VASc score improved risk stratification of AF patients with a CHADS2 score of 0-1. Using individual...

  7. Distribution of halogens between fluid and apatite during fluid-mediated replacement processes

    Science.gov (United States)

    Kusebauch, Christof; John, Timm; Whitehouse, Martin J.; Klemme, Stephan; Putnis, Andrew

    2015-12-01

    Apatite (Ca5(PO4)3(OH, F, Cl)) is one of the main host of halogens in magmatic and metamorphic rocks and plays a unique role during fluid-rock interaction as it incorporates halogens (i.e. F, Cl, Br, I) and OH from hydrothermal fluids to form a ternary solid solution of the endmembers F-apatite, Cl-apatite and OH-apatite. Here, we present an experimental study to investigate the processes during interaction of Cl-apatite with different aqueous solutions (KOH, NaCl, NaF of different concentration also doped with NaBr, NaI) at crustal conditions (400-700 °C and 0.2 GPa) leading to the formation of new apatite. We use the experimental results to calculate partition coefficients of halogens between apatite and fluid. Due to a coupled dissolution-reprecipitation mechanism new apatite is always formed as a pseudomorphic replacement of Cl-apatite. Additionally, some experiments produce new apatite also as an epitaxial overgrowth. The composition of new apatite is mainly governed by complex characteristics of the fluid phase from which it is precipitating and depends on composition of the fluid, temperature and fluid to mineral ratio. Furthermore, replaced apatite shows a compositional zonation, which is attributed to a compositional evolution of the coexisting fluid in local equilibrium with the newly formed apatite. Apatite/fluid partition coefficients for F depend on the concentration of F in the fluid and increase from 75 at high concentrations (460 μg/g F) to 300 at low concentrations (46 μg/g F) indicating a high compatibility of F in apatite. A correlation of Cl-concentration in apatite with Cl- concentration of fluid is not observed for experiments with highly saline solutions, composition of new apatite is rather governed by OH- concentration of the hydrothermal fluid. Low partition coefficients were measured for the larger halogens Br and I and vary between 0.7 * 10-3-152 * 10-3 for Br and 0.3 * 10-3-17 * 10-3 for I, respectively. Br seems to have D values of

  8. 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

  9. Serotonin reuptake inhibitors (SRIs) and the risk of fetal congenital heart anomalies (CHA) : An exploratory pharmacogenetics study

    NARCIS (Netherlands)

    Daud, Aizati Nur; Frederikse, Wilhelmina; Bergman, JEH; van der Vlies, P.; Hak, Eelko; Berger, Rudolf; Groen, Henk; Wilffert, Berend

    2017-01-01

    Introduction: Several studies reported the risk of CHA associated with prenatal use of SRIs, but the results have been inconsistent. Objective: To explore whether pharmacogenetics play a role in this teratogenicity using a gene-environment interaction study. Patients and methods: A total of 33

  10. Beta-methyl substitution of cyclohexylalanine in Dmt-Tic-Cha-Phe peptides results in highly potent delta opioid antagonists.

    Science.gov (United States)

    Tóth, Géza; Ioja, Eniko; Tömböly, Csaba; Ballet, Steven; Tourwé, Dirk; Péter, Antal; Martinek, Tamás; Chung, Nga N; Schiller, Peter W; Benyhe, Sándor; Borsodi, Anna

    2007-01-25

    The opioid peptide TIPP (H-Tyr-Tic-Phe-Phe-OH, Tic:1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) was substituted with Dmt (2',6'-dimethyltyrosine) and a new unnatural amino acid, beta-MeCha (beta-methyl-cyclohexylalanine). This double substitution led to a new series of opioid peptides displaying subnanomolar delta antagonist activity and mu agonist or antagonist properties depending on the configuration of the beta-MeCha residue. The most promising analog, H-Dmt-Tic-(2S,3S)-beta-MeCha-Phe-OH was a very selective delta antagonist both in the mouse vas deferens (MVD) assay (Ke = 0.241 +/- 0.05 nM) and in radioligand binding assay (K i delta = 0.48 +/- 0.05 nM, K i mu/K i delta = 2800). The epimeric peptide H-Dmt-Tic-(2S,3R)-beta-MeCha-Phe-OH and the corresponding peptide amide turned out to be mixed partial mu agonist/delta antagonists in the guinea pig ileum and MVD assays. Our results constitute further examples of the influence of Dmt and beta-methyl substitution as well as C-terminal amidation on the potency, selectivity, and signal transduction properties of TIPP related peptides. Some of these compounds represent valuable pharmacological tools for opioid research.

  11. AHP 24: A Multi-ethnic Village in Northeast Tibet - History, Ritual, and Daily Life in Chu cha

    Directory of Open Access Journals (Sweden)

    Stobs stag lha སྟོབས་སྟག་ལྷ།

    2013-09-01

    Full Text Available Multi-ethnic Chu cha Village in Mchod rten thang Township, Dpa' ris Tibetan Autonomous County, Gansu Province, China is described in terms of location; population; clothing; language; religion; history; and personal, family, and community rituals. Photographs provide additional information.

  12. 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.

  13. Global tropospheric hydroxyl distribution, budget and reactivity

    Science.gov (United States)

    Lelieveld, Jos; Gromov, Sergey; Pozzer, Andrea; Taraborrelli, Domenico

    2016-10-01

    The self-cleaning or oxidation capacity of the atmosphere is principally controlled by hydroxyl (OH) radicals in the troposphere. Hydroxyl has primary (P) and secondary (S) sources, the former mainly through the photodissociation of ozone, the latter through OH recycling in radical reaction chains. We used the recent Mainz Organics Mechanism (MOM) to advance volatile organic carbon (VOC) chemistry in the general circulation model EMAC (ECHAM/MESSy Atmospheric Chemistry) and show that S is larger than previously assumed. By including emissions of a large number of primary VOC, and accounting for their complete breakdown and intermediate products, MOM is mass-conserving and calculates substantially higher OH reactivity from VOC oxidation compared to predecessor models. Whereas previously P and S were found to be of similar magnitude, the present work indicates that S may be twice as large, mostly due to OH recycling in the free troposphere. Further, we find that nighttime OH formation may be significant in the polluted subtropical boundary layer in summer. With a mean OH recycling probability of about 67 %, global OH is buffered and not sensitive to perturbations by natural or anthropogenic emission changes. Complementary primary and secondary OH formation mechanisms in pristine and polluted environments in the continental and marine troposphere, connected through long-range transport of O3, can maintain stable global OH levels.

  14. CHA2DS2-VASc Score for Identifying Truly Low-Risk Atrial Fibrillation for Stroke

    DEFF Research Database (Denmark)

    Kim, Tae-Hoon; Yang, Pil-Sung; Kim, Daehoon

    2017-01-01

    -risk patients toward initially identifying patients with a truly low risk of ischemic stroke, who do not need antithrombotic therapy. We tested the predictive ability of the congestive heart failure, hypertension, age ≥75, diabetes mellitus, prior stroke or transient ischemic attack (doubled; CHADS2......), congestive heart failure, hypertension, age ≥75 (doubled), diabetes mellitus, prior stroke or transient ischemic attack (doubled), vascular disease, age 65 to 74, female (CHA2DS2-VASc), and Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) risk stratification schemes in oral anticoagulants...... naive patients with atrial fibrillation in a Korean nationwide sample cohort. METHODS: From January 2002 to December 2008, a total of 5855 oral anticoagulant naive patients with nonvalvular atrial fibrillation aged ≥20 years were enrolled from Korea National Health Insurance Service-Sample Cohort...

  15. Sécurisation et facilitation de la chaîne logistique globale

    Directory of Open Access Journals (Sweden)

    Alexandre Tribolet

    2013-11-01

    Full Text Available L’étude Sécurisation et facilitation de la chaîne logistique globale : les impacts macro et micro-économiques de la loi américaine 100 % scanning a été commandée en 2007 à l’UMR IDEES-CIRTAI, Université du Havre, par l’Organisation Mondiale des Douanes (OMD. Elle vise à cerner les enjeux de l’application de la loi « 100% scanning » prévue pour 2012 et votée en août 2007 par le Congrès américain. Cette loi intervient dans un contexte post « 11 septembre » et s’inscrit dans le cadre de la poli...

  16. 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

  17. Remediation of copper contaminated soil by using different particle sizes of apatite: a field experiment.

    Science.gov (United States)

    Xing, Jinfeng; Hu, Tiantian; Cang, Long; Zhou, Dongmei

    2016-01-01

    The particle size of apatite is one of the critical factors that influence the adsorption of heavy metals on apatite in the remediation of heavy metal contaminated soils using apatite. However, little research has been done evaluating the impact of different particle sizes of apatite on immobilization remediation of heavy metal polluted soils in field. In this study, the adsorption isothermal experiments of copper on three kinds of apatite was tested, and the field experiment by using different particle sizes apatite [nano-hydroxyapatite (NAP), micro-hydroxyapatite (MAP), ordinary particle apatite (OAP)] at a same dosage of 25.8 t/ha (1.16 %, W/W) was also conducted. Ryegrass was chosen as the test plant. The ryegrass biomass, the copper contents in ryegrass and the copper fractionations in soil were determined after field experiments. Results of adsorption experiments showed that the adsorption amounts of copper on OAP was the lowest among different particles. The adsorption amounts of copper on MAP was higher than NAP at high copper equilibrium concentration (>1 mmol L(-1)), an opposite trend was obtained at low copper concentration (experiment, we found that the application of different apatites could effectively increase the soil pH, decrease the available copper concentration in soil, provide more nutrient phosphate and promote the growth of ryegrass. The ryegrass biomass and the copper accumulation in ryegrass were the highest in MAP among all treatments. The effective order of apatite in phytoremediation of copper contaminated field soil was MAP > NAP > OAP, which was attributed to the high adsorption capacity of copper and the strong releasing of phosphate by MAP.

  18. The Relationships between Atrial Electromechanical Delay and CHA2DS2-VASc Score in Patients Diagnosed with Paroxysmal AF.

    Science.gov (United States)

    Nar, Gökay; İnci, Sinan; Aksan, Gökhan; Soylu, Korhan; Demirelli, Selami; Nar, Rukiye

    2015-09-01

    This study aims to evaluate the relationship between atrial electromechanical delay (AEMD) times and CHA2DS2-VASc scores in patients diagnosed with paroxysmal atrial fibrillation (PAF). The study included a total of 74 patients, 34 of whom were diagnosed with PAF and 40 were included in the control group. The CHA2DS2-VASc score was calculated for each patient. Additionally, blood samples were taken from all patients and transthoracic echocardiographic measurements were made. Left atrial mechanical functions and AEMD were calculated. Mean CHA2DS2-VASc score measured was 2.24 ± 1.53 in PAF group. There was no significant difference between the groups when the patients were evaluated for baseline characteristics and laboratory parameters (P > 0.05) The echocardiographic evaluation of LA mechanical functions showed that only LA minimum volume (19 ± 6.4 vs. 16.7 ± 4.6, P = 0.02) and LA presystolic volume (28.9 ± 7 vs. 25.1 ± 5.7, P = 0.01) were higher in the PAF group. When AEMD was compared between the groups; lateral PA, septal PA, tricuspid PA, Interatrial EMD, and intraatrial EMD were significantly extended compared to control group (P < 0.001) CHA2DS2-VASc score was correlated with Lateral atrial PA (P < 0.001, r = 0.524), Septal atrial PA (P < 0.001, r = 0.45), Interatrial EMD (P < 0.001, r = 0.54), and intraatrial EMD (P < 0.001, r = 0.51) times. The present study shows that AEMD times increase in patients with PAF compared to the control group. Furthermore, this study revealed a correlation between AEMD times and CHA2DS2-VASc score, as well showed that extended AEMD time may be associated with thromboembolism risk. © 2014, Wiley Periodicals, Inc.

  19. Transfer of apatite coating from porogens to scaffolds: uniform apatite coating within porous poly(DL-lactic-co-glycolic acid) scaffold in vitro.

    Science.gov (United States)

    Li, Jiashen; Beaussart, Audrey; Chen, Yun; Mak, Arthur F T

    2007-01-01

    Strategies to bone tissue engineering have focused on the use of synthetic or natural degradable materials as scaffolds for cell transplantation to guide bone regeneration. Biocompatibility, biodegradability, biomechanical integrity, and osteoconductivity are important requirements for the scaffold materials. This study explored a new approach of apatite coating to enhance the osteoconductivity of a synthetic degradable poly(DL-lactic-co-glycolic acid) (PLGA) scaffold. The new approach was developed to ensure a relatively uniform apatite coating on the interior pore surfaces deep inside a scaffold, even for a relatively thick scaffold with small pores. Apatite was first coated on the surface of paraffin spheres of the desirable sizes. The paraffin spheres were then molded to form a foam. PLGA/pyridine solution was cast into the interspaces among the paraffin spheres. After the paraffin spheres were dissolved and removed by cyclohexane, PLGA scaffold with controlled pore size, good interconnectivity and high porosity was obtained with apatite left on the pore surface uniformly throughout the whole scaffold. The scaffold and apatite coating were characterized using thermogravimetry analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry. (c) 2006 Wiley Periodicals, Inc.

  20. Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

    Directory of Open Access Journals (Sweden)

    Sasha Krneta

    2017-08-01

    Full Text Available Apatite is a common magmatic accessory in the intrusive rocks hosting the giant ~1590 Ma Olympic Dam (OD iron-oxide copper gold (IOCG ore system, South Australia. Moreover, hydrothermal apatite is a locally abundant mineral throughout the altered and mineralized rocks within and enclosing the deposit. Based on compositional data for zoned apatite, we evaluate whether changes in the morphology and the rare earth element and Y (REY chemistry of apatite can be used to constrain the fluid evolution from early to late hydrothermal stages at OD. The ~1.6 Ga Roxby Downs granite (RDG, host to the OD deposit, contains apatite as a magmatic accessory, locally in the high concentrations associated with mafic enclaves. Magmatic apatite commonly contains REY-poor cores and REY-enriched margins. The cores display a light rare earth element (LREE-enriched chondrite-normalized fractionation pattern with a strong negative Eu anomaly. In contrast, later hydrothermal apatite, confined to samples where magmatic apatite has been obliterated due to advanced hematite-sericite alteration, displays a conspicuous, convex, middle rare earth element (MREE-enriched pattern with a weak negative Eu anomaly. Such grains contain abundant inclusions of florencite and sericite. Within high-grade bornite ores from the deposit, apatite displays an extremely highly MREE-enriched chondrite-normalized fractionation trend with a positive Eu anomaly. Concentrations of U and Th in apatite mimic the behaviour of ∑REY and are richest in magmatic apatite hosted by RDG and the hydrothermal rims surrounding them. The shift from characteristic LREE-enriched magmatic and early hydrothermal apatite to later hydrothermal apatite displaying marked MREE-enriched trends (with lower U, Th, Pb and ∑REY concentrations reflects the magmatic to hydrothermal transition. Additionally, the strong positive Eu anomaly in the MREE-enriched trends of apatite in high-grade bornite ores are attributable to

  1. Do physicians correctly calculate thromboembolic risk scores? A comparison of concordance between manual and computer-based calculation of CHADS2 and CHA2 DS2 -VASc scores.

    Science.gov (United States)

    Esteve-Pastor, M A; Marín, F; Bertomeu-Martinez, V; Roldán-Rabadán, I; Cequier-Fillat, Á; Badimon, L; Muñiz-García, J; Valdés, M; Anguita-Sánchez, M

    2016-05-01

    Clinical risk scores, CHADS2 and CHA2 DS2 -VASc scores, are the established tools for assessing stroke risk in patients with atrial fibrillation (AF). The aim of this study is to assess concordance between manual and computer-based calculation of CHADS2 and CHA2 DS2 -VASc scores, as well as to analyse the patient categories using CHADS2 and the potential improvement on stroke risk stratification with CHA2 DS2 -VASc score. We linked data from Atrial Fibrillation Spanish registry FANTASIIA. Between June 2013 and March 2014, 1318 consecutive outpatients were recruited. We explore the concordance between manual scoring and computer-based calculation. We compare the distribution of embolic risk of patients using both CHADS2 and CHA2 DS2 -VASc scores The mean age was 73.8 ± 9.4 years, and 758 (57.5%) were male. For CHADS2 score, concordance between manual scoring and computer-based calculation was 92.5%, whereas for CHA2 DS2 -VASc score was 96.4%. In CHADS2 score, 6.37% of patients with AF changed indication on antithrombotic therapy (3.49% of patients with no treatment changed to need antithrombotic treatment and 2.88% of patients otherwise). Using CHA2 DS2 -VASc score, only 0.45% of patients with AF needed to change in the recommendation of antithrombotic therapy. We have found a strong concordance between manual and computer-based score calculation of both CHADS2 and CHA2 DS2 -VASc risk scores with minimal changes in anticoagulation recommendations. The use of CHA2 DS2 -VASc score significantly improves classification of AF patients at low and intermediate risk of stroke into higher grade of thromboembolic score. Moreover, CHA2 DS2 -VASc score could identify 'truly low risk' patients compared with CHADS2 score. © 2016 Royal Australasian College of Physicians.

  2. Genetic characterization of the cell-adapted PanAsia strain of foot-and-mouth disease virus O/Fujian/CHA/5/99 isolated from swine

    Science.gov (United States)

    2010-01-01

    Background According to Office International Des Epizooties (OIE) Bulletin, the PanAsia strain of Foot-and-Mouth Disease Virus (FMDV) was invaded into the People's Republic of China in May 1999. It was confirmed that the outbreaks occurred in Tibet, Hainan and Fujian provinces. In total, 1280 susceptible animals (68 cattle, 1212 swine) were destroyed for the epidemic control. To investigate the distinct biological properties, we performed plaque assay, estimated the pathogenicity in suckling mice and determined the complete genomic sequence of FMDV swine-isolated O/Fujian/CHA/5/99 strain. In addition, a molecular modeling was carried out with the external capsid proteins. Results The pathogenicity study showed that O/Fujian/CHA/5/99 had high virulence with respect to infection in 3-day-old suckling-mice (LD50 = 10-8.3), compared to O/Tibet/CHA/1/99 (LD50 = 10-7.0) which isolated from bovine. The plaque assay was distinguishable between O/Fujian/CHA/5/99 and O/Tibet/CHA/1/99 by their plaque phenotypes. O/Fujian/CHA/5/99 formed large plaque while O/Tibet/CHA/1/99 formed small plaque. The 8,172 nucleotides (nt) of O/Fujian/CHA/5/99 was sequenced, and a phylogenetic tree was generated from the complete nucleotide sequences of VP1 compared with other FMDV reference strains. The identity data showed that O/Fujian/CHA/5/99 is closely related to O/AS/SKR/2002 (94.1% similarity). Based on multiple sequence alignments, comparison of sequences showed that the characteristic nucleotide/amino acid mutations were found in the whole genome of O/Fujian/CHA/5/99. Conclusion Our finding suggested that C275T substitution in IRES of O/Fujian/CHA/5/99 may induce the stability of domain 3 for the whole element function. The structure prediction indicated that most of 14 amino acid substitutions are fixed in the capsid of O/Fujian/CHA/5/99 around B-C loop and E-F loop of VP2 (antigenic site 2), and G-H loop of VP1 (antigenic site 1), respectively. These results implicated that these

  3. 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.

  4. Dissolution mechanism of calcium apatites in acids: A review of literature

    Science.gov (United States)

    Dorozhkin, Sergey V

    2012-01-01

    Eight dissolution models of calcium apatites (both fluorapatite and hydroxyapatite) in acids were drawn from the published literature, analyzed and discussed. Major limitations and drawbacks of the models were conversed in details. The models were shown to deal with different aspects of apatite dissolution phenomenon and none of them was able to describe the dissolution process in general. Therefore, an attempt to combine the findings obtained by different researchers was performed which resulted in creation of the general description of apatite dissolution in acids. For this purpose, eight dissolution models were assumed to complement each other and provide the correct description of the specific aspects of apatite dissolution. The general description considers all possible dissolution stages involved and points out to some missing and unclear phenomena to be experimentally studied and verified in future. This creates a new methodological approach to investigate reaction mechanisms based on sets of affine data, obtained by various research groups under dissimilar experimental conditions. PMID:25237611

  5. Synthesis and characterization of nanocrystalline apatites from eggshells at different Ca/P ratios

    Energy Technology Data Exchange (ETDEWEB)

    Siddharthan, A; Sampath Kumar, T S; Seshadri, S K, E-mail: tssk@iitm.ac.i [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai-600 036 (India)

    2009-08-15

    Nanocrystalline apatites with different Ca/P ratios were synthesized using eggshell as a calcium source by microwave processing. The apatites were found to have a minor amount of Mg, Sr, Si and Na ions inherited from the eggshells. The presence of several foreign ions results in a perturbed lattice structure indicated by an increase in lattice constants and shift in vibrational frequencies of the functional groups. The apatites were heat treated to investigate the influence of foreign ions on thermal stability. The minor amounts of ions do not affect the thermal stability. The differences in thermal behaviour of these apatites were due to the presence of HPO{sup 2-}{sub 4} ions only and not due to other ions because of their low content.

  6. Hydroxyapatite and Carbonated Apatite as Models for the Dissolution Behavior of Human Dental Enamel

    National Research Council Canada - National Science Library

    Budz, J.A; Lore, M; Nancollas, G.H

    1987-01-01

    ... to understand the mechanism of dental caries. In the present study, kinetic comparisons of the dissolution of hydroxyapatite, carbonated apatite, and ground human dental enamel have been made in order that the appropriateness of these synthetic...

  7. Improvement of RVNRL film properties by adding fumed silica and hydroxy apatite

    Directory of Open Access Journals (Sweden)

    Adul Thiangchanya

    2003-01-01

    Full Text Available The effect of adding fumed silica and hydroxy apatite to Radiation Vulcanized Natural Rubber Latex (RVNRL for improving tear strength, aging properties, degradability and water-soluble protein content of rubber films has been investigated. The addition of fumed silica and hydroxy apatite in RVNRL improves tear strength and aging properties of rubber films, whereas tensile strength and degradability of rubber films were unchanged during storage at room temperature. The water-soluble protein content in rubber films was reduced by immobilization of the fumed silica and hydroxy apatite and enhanced by addition of ZnO. This may reduce allergy problems of natural rubber latex products caused by water-soluble protein. The MST of the RVNRL with fumed silica and hydroxy apatite indicated that the latex must be used within two months after mixing because of its stability.

  8. Geochemistry of Apatite in Climactic and Pre-Climactic Tephra from Mt. Mazama, Crater Lake, Oregon

    Science.gov (United States)

    Mandeville, C. W.; Langstaff, M.

    2007-12-01

    Apatite is a common accessory mineral in arc volcanic rocks that potentially records information about the dissolved volatile (S,Cl,F,OH) and trace-element concentrations (Sr, Ba, REEs) of the melt from which it crystallized. In a previous study of apatite from arc and convergent margin volcanic rocks, Peng et al. (1997) reported 0.63 wt.% SO3 in Mazama apatite grains with a corresponding SrO content of 0.18 wt.%, comprising some of the highest SO3 and SrO values in their data. Our electron microprobe study of apatite in climactic and pre-climactic Mazama tephra was done in order to assess possible correlation of apatite SO3 with Sr content of low-Sr and high-Sr recharge magmas identified based on whole-rock and matrix glass data (Bacon and Druitt, 1988) and Sr content of plagioclase (Druitt and Bacon 1989). Samples chosen represent all magmatic components erupted during the ca. 7700 year before present climactic eruption and precursor Llao Rock and Cleetwood eruptions. We compare the S, Cl, and F content of Mazama apatites with recent experimental data for S, Cl, and F partitioning between apatite and melt and with dissolved volatiles previously measured in melt inclusions from corresponding or similar Mazama samples. Our electron microprobe data confirm the presence of rare Mazama apatites with up to 0.78 wt.% SO3 and 0.12 wt.% SrO in Llao Rock, Cleetwood, and climactic scoria and pumice samples. However, high SO3 and SrO apatites are not restricted to high-Sr scoria hosts, but have been observed in low-Sr scoria, in Llao Rock rhyodacitic pumices and in Cleetwood rhyodacitic pumices, thus indicating significant magma mixing prior to the Llao Rock, Cleetwood and climactic eruptions. Most apatite SO3 and SrO data falls within the 0.06 to 0.36 wt.% and 0.04 to 0.12 wt.% range, respectively. Experimental data on SO3 partitioning between apatite and melt and maximum sulfur contents of 300 to 350 ppm measured in climactic and Cleetwood rhyodacitic melt inclusions

  9. Compression and rupture cycles as tools for compressibility characterization application to apatitic calcium phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Pontier, C. [S.P.C.T.S., Faculte des Sciences, Limoges (France); G.E.F., Faculte de Pharmacie, Limoges (France); Viana, M.; Chulia, D. [G.E.F., Faculte de Pharmacie, Limoges (France); Champion, E.; Bernache-Assollant, D. [S.P.C.T.S., Faculte des Sciences, Limoges (France)

    2002-07-01

    Measurement of the cycles of compression and rupture helps to understand the phenomena occurring during compaction. Different parameters are deduced from the cycles, such as the packing of the material and energies used during compression. The ratio between the energy of rupture and the energy of compaction defines the efficacy of compaction of the materials. This technique is applied to ceramic materials using apatitic calcium phosphates with a Ca/P molar ratio of 1.5 (apatitic tricalcium phosphate and {beta}-tricalcium phosphate) and 1.667 (stoichiometric hydroxyapatite). The methodology uses a uniaxial instrumented press to plot the cycles of compaction and rupture. The results point out the good compaction and cohesion properties of apatitic tricalcium phosphate, compared to the other apatitic materials. (orig.)

  10. Site-specific equilibrium isotopic fractionation of oxygen, carbon and calcium in apatite

    Science.gov (United States)

    Aufort, Julie; Ségalen, Loïc; Gervais, Christel; Paulatto, Lorenzo; Blanchard, Marc; Balan, Etienne

    2017-12-01

    The stable isotope composition of biogenic apatite is an important geochemical marker that can record environmental parameters and is widely used to infer past climates, biomineralization processes, dietary preferences and habitat of vertebrates. In this study, theoretical equilibrium isotopic fractionation of oxygen, carbon and calcium in hydroxyapatite and carbonate-bearing hydroxyapatite is investigated using first-principles methods based on density-functional theory and compared to the theoretical isotopic fractionation properties of calcite, CO2 and H2O. Considering the variability of apatite crystal-chemistry, special attention is given to specific contributions of crystal sites to isotopic fractionation. Significant internal fractionation is calculated for oxygen and carbon isotopes in CO3 between the different structural sites occupied by carbonate groups in apatite (typically 7‰ for both 18O/16O and 13C/12C fractionation at 37 °C). Compared with calcite-water oxygen isotope fractionation, occurrence of A-type substitution in apatite structure, in addition to the main B-type substitution, could explain the larger temperature dependence of oxygen isotope fractionation measured at low temperature between carbonate in apatite and water. Theoretical internal fractionation of oxygen isotopes between carbonate and phosphate in B-type carbonated apatite (∼8‰ at 37 °C) is consistent with experimental values obtained from modern and well-preserved fossil bio-apatites. Concerning calcium, theoretical results suggest a small fractionation between apatite and calcite (-0.17‰ at 37 °C). Internal fractionation reaching 0.8‰ at 37 °C occurs between the two Ca sites in hydroxyapatite. Furthermore, the Ca isotopic fractionation properties of apatite are affected by the occurrence of carbonate groups, which could contribute to the variability observed on natural samples. Owing to the complexity of apatite crystal-chemistry and in light of the theoretical

  11. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, E.H., E-mail: md.ezharul.hoque@med.monash.edu.my [Jeffrey Cheah School of Medicine and Health Sciences, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan (Malaysia)

    2011-06-17

    Highlights: {yields} Cytoplasmic stability of plasmid DNA is enhanced by fluoride incorporation into carbonate apatite carrier. {yields} Fluoridated carbonate apatite promotes a robust increase in transgene expression. {yields} 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.

  13. Apatite formation on non-woven fabric of carboxymethylated chitin in SBF.

    Science.gov (United States)

    Kokubo, Tadashi; Hanakawa, Masayuki; Kawashita, Masakazu; Minoda, Masahiko; Beppu, Toshiyuki; Miyamoto, Takeaki; Nakamura, Takashi

    2004-08-01

    Chitin fibres constituting a non-woven fabric were carboxymethylated in monochloro acetic acid and treated with saturated Ca(OH)(2) aqueous solution. Within 3 days in a simulated body fluid with pH value and ion concentrations nearly equal to those of human blood plasma, a bonelike apatite layer formed on the surface of fibres of the treated fabric. The apatite-chitin fibre composite thus prepared is expected to be useful as a flexible bioactive bone-repairing material.

  14. Diagenetic uptake of rare earth elements by conodont apatite

    Science.gov (United States)

    Zhang, L.; Algeo, T. J.; Cao, L.; Zhao, L.; Chen, Z. Q.; Li, Z.

    2015-12-01

    The rare earth element (REE) composition of bioapatite has long been used as a proxy for ancient seawater chemistry and paleomarine environmental reconstruction, based on the assumption of preservation of a hydrogenous (seawater-derived) REE signal. Recent work, however, has begun to question the provenance of REEs in conodonts, emphasizing the importance of REEs released by the lithogenous fraction of the sediment and subsequently adsorbed onto conodont apatite in the burial environment. Here, we investigate patterns of REE and trace-element abundance in conodonts and their host sediments from the Early to Late Ordovician Huanghuachang and Chenjiahe sections of Hubei Province, South China. Several lines of evidence indicate that REEs in the conodont samples were acquired mainly from clay minerals in the host sediment during burial diagenesis: (1) REEs in conodonts show a strong positive correlation to Th and other lithogenic elements; (2) conodonts and whole-rock samples show general patterns of REE and trace-element enrichment that are highly similar to each other and bear no resemblance to seawater elemental concentrations; (3) similar patterns are observed in Triassic conodonts and whole-rock samples; and (4) Y/Ho ratios in conodonts are mostly 90% of REEs from lithogenous sources. Conodonts show pronounced middle rare earth element (MREE) enrichment, a pattern that is unambiguously of diagenetic origin owing to its association with lower Y/Ho ratios. With increasing MREE enrichment of conodont samples, U concentrations and LaN/YbN ratios shift from high to low, and Mn concentrations from low to high. These patterns suggest that conodont diagenesis was initiated at shallow burial depths under suboxic conditions (i.e., in the zone of Mn(IV) and Fe(III) reduction) but continued at greater burial depths, with most acquisition of secondary REEs at later diagenetic stages. Our findings indicate that (1) conodont apatite frequently does not preserve a recognizable

  15. Growth and structure of lamellar mixed crystals of octacalcium phosphate and apatite in a model system of enamel formation

    Science.gov (United States)

    Iijima, Mayumi; Tohda, Hisako; Moriwaki, Yutaka

    1992-02-01

    Lamellar mixed crystals of octacalcium phosphate (OCP) and apatite were synthesized in a model system of enamel formation in the presence of 1 ppm F - at 37°C and at pH 6.5. The crystal has long and thin plate-like morphology and contained a distinct OCP lamella in the center of the apatite matrix. The thickness of the OCP lamella in the a-axis direction is one to several unit cells. Some apatite crystals embed a central layer instead of the distinct OCP lamella. The OCP lamella and the central layer are parallel to the (100) plane of the apatite, while the c-axis of the OCP is parallel to the c-axis of the apatite. Analysis suggests that (1) F - causes the growth of apatite on OCP and regulates the formation of the lamellar mixed crystals of OCP and apatite, (2) the OCP lamella acts as a template for the subsequent epitaxial growth of apatite, and (3) the lamellar mixed crystals grow mainly in the c-axis direction of both the OCP and apatite. These results strongly support the idea that enamel crystals take a thin and long ribbon-like morphology when the initially formed OCP acts as a template for the subsequent growth of apatite in the enamel formation.

  16. Apatite deposition on titanium surfaces--the role of albumin adsorption.

    Science.gov (United States)

    Serro, A P; Fernandes, A C; Saramago, B; Lima, J; Barbosa, M A

    1997-07-01

    Titanium implant surfaces are known to spontaneously nucleate apatite layers when in contact with simulated body fluids. However, adsorption of proteins may influence the process of apatite layer formation. In this study the role of bovine serum albumin (BSA) adsorption in the process of apatite deposition on titanium substrates is investigated. Deposition of calcium phosphate was induced by immersing titanium substrates in a Hank's balanced salt solution (HBSS) for times ranging from 1 to 23 days. The resulting substrates were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), wettability measurements and electrochemical impedance determinations. All these methods indicate the presence of a calcium phosphate layer. The same procedure was repeated substituting HBSS with a solution of BSA in HBSS. Although SEM, EDS and electrochemical impedance spectra do not reveal the presence of an apatite layer, XPS analysis strongly indicates that the inhibition of apatite formation by BSA is only partial. The competition between BSA adsorption and apatite deposition seems to lead to a mixed film where the protein co-exists with calcium phosphate. Wettability studies suggest that this surface film is heterogeneous and porous, similar to the thicker films formed in albumin-free HBSS.

  17. Prediction of apatite lattice constants from their constituent elemental radii and artificial intelligence methods.

    Science.gov (United States)

    Wu, P; Zeng, Y Z; Wang, C M

    2004-03-01

    Lattice constants (LCs) of all possible 96 apatite compounds, A(5)(BO(4))(3)C, constituted by A[double bond]Ba(2+), Ca(2+), Cd(2+), Pb(2+), Sr(2+), Mn(2+); B[double bond]As(5+), Cr(5+), P(5+), V(5+); and C[double bond]F(1-), Cl(1-), Br(1-), OH(1-), are predicted from their elemental ionic radii, using pattern recognition (PR) and artificial neural networks (ANN) techniques. In particular, by a PR study it is demonstrated that ionic radii predominantly govern the LCs of apatites. Furthermore, by using ANN techniques, prediction models of LCs a and c are developed, which reproduce well the measured LCs (R(2)=0.98). All the literature reported on 30 pure and 22 mixed apatite compounds are collected and used in the present work. LCs of all possible 66 new apatites (assuming they exist) are estimated by the developed ANN models. These proposed new apatites may be of interest to biomedical research especially in the design of new apatite biomaterials for bone remodeling. Similarly these techniques may also be applied in the study of interface growth behaviors involving other biomaterials.

  18. Footprinting protein-DNA complexes using the hydroxyl radical.

    Science.gov (United States)

    Jain, Swapan S; Tullius, Thomas D

    2008-01-01

    Hydroxyl radical footprinting has been widely used for studying the structure of DNA and DNA-protein complexes. The high reactivity and lack of base specificity of the hydroxyl radical makes it an excellent probe for high-resolution footprinting of DNA-protein complexes; this technique can provide structural detail that is not achievable using DNase I footprinting. Hydroxyl radical footprinting experiments can be carried out using readily available and inexpensive reagents and lab equipment. This method involves using the hydroxyl radical to cleave a nucleic acid molecule that is bound to a protein, followed by separating the cleavage products on a denaturing electrophoresis gel to identify the protein-binding sites on the nucleic acid molecule. We describe a protocol for hydroxyl radical footprinting of DNA-protein complexes, along with a troubleshooting guide, that allows researchers to obtain efficient cleavage of DNA in the presence and absence of proteins. This protocol can be completed in 2 d.

  19. 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)

  20. Electron spin resonance in silicon substituted apatite and tricalcium phosphate.

    Science.gov (United States)

    Pietak, Alexis M; Reid, Joel W; Sayer, Michael

    2005-06-01

    Impurity centers associated with silicon have been observed in the phase mixture of silicon substituted apatite (Si-Ap) and silicon stabilized tricalcium phosphate (Si-TCP) using electron spin resonance (ESR). Two unique centers occur upon addition of SiO2 to the calcium phosphate system: an orthorhombic center with g-values 2.0072+/-0.0001, 2.0024+/-0.0001 and 2.0003+/-0.0001 (Si-h1) and a center with tetrahedral symmetry having g-values components 2.0054+/-0.0001 and 1.9992+/-0.0003 (Si-h2). Both centers are hypothesized to be characteristic of defects associated with silicon in the Si-Ap phase. Through comparison of the intensity of F-OH centers in undoped calcium hydroxyapatite (HA) prepared with various levels of OH occupancy, a relationship is demonstrated between the ESR intensity of an F-center signal with g = 2.0019+0.0004 (F-OH) and the OH occupation of HA. Relative changes in the intensity of ESR signals Si-h1 and F-OH are consistent with a chemical model describing the substitution of SiO4(4-) for PO4(3-) in HA with the creation of OH- vacancies as charge compensation, resulting in a mixed phase composition of Si-Ap and Si-TCP that results when a hydroxyapatite precipitate (HA) is heated in the presence of added SiO2.

  1. Infrared spectra of carbonate apatites: v2-Region bands.

    Science.gov (United States)

    Fleet, Michael E

    2009-03-01

    The proportions of A and B carbonate ions in a selection of AB carbonate apatites, including hydroxyapatite (CHAP), chlorapatite (CCLAP) and fluorapatite (CFAP), have been obtained using the out-of-plane bend (nu(2)) bands of Fourier transform infrared (FTIR) spectra. Band area ratios (B/A) are in very good agreement with site occupancies from single-crystal X-ray structure refinement; the correlation is linear (1:1) for B/A values ranging up to three. Most compositions have nu(2) spectra with one band for A carbonate (at 878-880 cm(-1)) and one for B (at 870-872 cm(-1)). Na-free AB CHAP has a third prominent band at 862 cm(-1), which is assigned to the stuffed channel species (A2), and Na-bearing CFAP has a third band at 864 cm(-1), which is assigned to a second B carbonate environment (B2). The A2 and B2 assignments are based largely on spectral changes in annealed samples.

  2. Searching for a One-Step Bioprocess for the Production of Hydroxyl Fatty Acids and Hydroxyl Oils from Soybean Oil

    Science.gov (United States)

    Soybean oil is produced domestically in large supply, averaging over 20 billion pounds per year with an annual carryover of more than one billion pounds. It is important to find new uses for this surplus soybean oil. Hydroxyl fatty acids and hydroxyl oils are platform materials for specialty chemi...

  3. Karakteristik dan Aktivitas Antibakteri Scaffold Membran Cangkang Telur yang Diaktivasi Karbonat Apatit

    Directory of Open Access Journals (Sweden)

    Mirantini Aprilisna

    2015-06-01

    membran cangkang telur + karbonat apatit + SBF selama 7 hari, sampel D membran cangkang telur + karbonat apatit + SBF selama 14 hari, dan sampel E membran cangkang telur + karbonat apatit + SBF selama 21 hari. Uji sampel yaitu karakterisasi menggunakan ATR FTIR dan SEM, serta uji aktivitas antibakteri menggunakan metode difusi. Hasil karakterisasi SEM menunjukkan pori-pori serat 10-20μm pada semua sampel, ATR FTIR sampel B, C, D, E menunjukkan peningkatan gugus apatit dibanding sampel A. Pengujian antibakteri terhadap Staphylococcus aureus menunjukkan zona bening pada setiap sampel. Perhitungan jumlah koloni setiap sampel yaitu terbanyak koloninya sampel A ±78x105 CFU/ml, dan paling sedikit koloninya sampel B ±14x105 CFU/ml. Kesimpulan penelitian ini yaitu karakteristik dan aktivitas antibakteri scaffold membran cangkang telur yang diaktivasi karbonat apatit mengandung bahan bioaktif, bersifat biodegradasi dan menunjukkan aktivitas antibakteri.   Characteristic And Antibacterial Activity Of Egg-Shell Membrane Scaffold Activated By Carbonate Apatite. The loss of bone structure that can be caused by periodontal disease and trauma can be treated by installation of graft. The installation of graft is vulnerable to bacterial invasion, so that the alternative is to make a scaffold with antibacterial activity. Scaffold manufacturing in engineering system must have biocompatible, biodegradable, and bioactive properties. This research used egg-shell membrane (ESM as scaffold template, alginate, chitosan, carbonate apatite, and SBF solution. The purpose of this research is to know the characteristics, and antibacterial activity of eggshell membrane scaffold which is activated by carbonate apatite. This research used laboratory experimental method by dividing the samples into five groups that were ESM as sample A, ESM with carbonate apatite as sample B, ESM with carbonate apatite soaked in SBF sol for 7days as sample C, ESM with carbonate apatite soaked in

  4. The Identification and Synthesis of Lead Apatite Minerals Formed in Lead Water Pipes

    Directory of Open Access Journals (Sweden)

    Jeremy D. Hopwood

    2016-01-01

    Full Text Available Phosphate is added to drinking water in the UK to minimise the release of lead from lead water pipes. The phosphate encourages the formation of insoluble lead apatites on the walls of the pipe. Hydroxylpyromorphite Pb5(PO43OH is the lead apatite that is most often used to model lead levels in tap water; however, its presence has not been confirmed. Our aims were to identify the lead pipe apatite and synthesise it. The synthetic mineral would then be used in future solubility studies to produce better predictions of lead levels in tap water. XRD and FTIR were used to characterise the minerals on a range of lead pipes. Pyromorphite and hydroxylpyromorphite were absent and instead a range of mixed calcium lead apatites were present. For every five lead ions in the general formula Pb5(PO43X between one and two ions were replaced with calcium and there was evidence of substitution of PO43- by either CO32- or HPO42-. Calcium lead apatites with similar unit cell dimensions to those found on lead water pipes were then synthesised. The calcium : lead ratio in these reaction mixtures was in excess of 500 : 1 and the resulting crystals were shown by TEM to be nanosized rods and flakes. The synthetic apatites that most closely resembled the unit cell dimensions of the apatites on lead water pipes were shown to be Pb3.4Ca1.3(PO43Cl0.03OH0.97, Pb3.6Ca1.2(PO43Cl0.07OH0.93, and Pb3.6Ca1.2(PO43Cl0.27OH0.73.

  5. In-vitro apatite formation capacity of a bioactive glass - containing toothpaste.

    Science.gov (United States)

    Kanwal, Nasima; Brauer, Delia S; Earl, Jonathan; Wilson, Rory M; Karpukhina, Natalia; Hill, Robert G

    2017-10-31

    The in-vitro dissolution of bioactive glass-based toothpastes and their capacity to form apatite-like phases in buffer solutions have been investigated. The commercial toothpaste samples were tested on immersion in artificial saliva, Earle's salt solution and Tris buffer for duration from 10min to four days. The powder samples collected at the end of the immersion were studied using solid-state 31P and 19F nuclear magnetic resonance spectroscopy (NMR), X-ray powder diffraction and Fourier transform infrared (FTIR) spectroscopy. The fluoride concentration in the solution remained after the immersion was measured. In artificial saliva and in presence of sodium monofluorophosphate (MFP), the bioactive glass and bioactive glass-based toothpastes formed fluoridated apatite-like phases in under 10min. A small amount of apatite-like phase was detected by 31P NMR in the toothpaste with MFP but no bioactive glass. The toothpaste with bioactive glass but no fluoride formed an apatite-like phase as rapidly as the paste containing bioactive glass and fluoride. By contrast, apatite-like phase formation was much slower in Earle's salt solution than artificial saliva and slower than Tris buffer. The results of this lab-based study showed that the toothpaste with MFP and bioactive glass formed a fluoridated apatite in artificial saliva and in Tris buffer, as did the mixture of bioactive glass and MFP. The presence of fluoride in bioactive glass-containing toothpastes can potentially lead to the formation of a fluoridated apatite, which may result in improved clinical effectiveness and durability. However, this should be further tested intra-orally. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. 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

  7. 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.

  8. Synthesis and characterization of a new class of stabilized apatite nanoparticles and applying the particles to in situ Pb immobilization in a fire-range soil.

    Science.gov (United States)

    Liu, Ruiqiang; Zhao, Dongye

    2013-04-01

    Phosphate compounds and the related materials are effective agents for in situ immobilization of heavy metals in contaminated soils. Problems associated with using these phosphate materials include difficulties in delivering the solid phosphate minerals to the deep contaminated zones or risks of eutrophication with applying soluble phosphates. Therefore, a new class of apatite nanoparticles was synthesized using carboxymethyl cellulose as a stabilizer in order to increase the dispersion rate of phosphate in soils but without introducing significant amount of soluble phosphate into the environment. The product was confirmed by XRD as chlorapatite (Ca5(PO4)3Cl) with poor crystallinity. TEM and SEM revealed that the particles were spherical or irregular in shape with sizes spanning from a few nm to around 200 nm. FTIR spectra suggested that Ca(II) cations formed outer-sphere bonds with carboxyl and hydroxyl groups in cellulose molecules, thus inhibiting further agglomeration of the particles. Dry combustion data supported a formula of [C6H7O2(OH)2OCH2COOCa5(PO4)3Cl]n for the nano-apatite composite. Laboratory tests showed that the nanoparticles could effectively decrease the TCLP-leachable Pb fraction in a Pb-contaminated soil from 66% to 10% after one-month amendment with a ratio of 2 mL solution to 1g soil and the resultant Pb content in the TCLP solution was reduced to 12 from 94 mg L(-1). When the amendment ratio was increased by 5 times, the leachable Pb was further reduced to 3.8 mg L(-1) with only about 3% of the soil Pb leachable. The soil sample, containing an average of 2.7×10(3)mg Pb kg(-1), was taken from a shooting-range in Southern USA. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Radioprotective activity of some. beta. -hydroxylated indole-alkylamines

    Energy Technology Data Exchange (ETDEWEB)

    Deanovic, Z.; Trescec, A.; Kveder, S.; Iskric, S.; Supek, Z.

    1982-06-01

    Chain ..beta..-hydroxylated derivatives of tryptamine, 5-methoxytryptamine and 5-hydroxytryptamine (serotonin), respectively, were tested as radioprotectors in X-ray-irradiated mice. At midlethal dose of irradiation (725 cGy), tryptamine and serotonin protected all the animals, ..beta..-hydroxylated tryptamine was only slightly less effective (survival 85%). On the contrary, when mice were irradiated with absolutely lethal dose (900 cGy), only ..beta..-hydroxylated derivative of serotonin gave complete (100%) protection to the animals; 5-hydroxytryptamine and 5-methoxytryptamine protected about 90% of the animals. ..beta..-hydroxy-5-methosytryptamine 35%, tryptamine 29%, whereas ..beta..-hydroxytryptamine did not give any protection.

  10. Regioselective alkane hydroxylation with a mutant AlkB enzyme

    Science.gov (United States)

    Koch, Daniel J.; Arnold, Frances H.

    2012-11-13

    AlkB from Pseudomonas putida was engineered using in-vivo directed evolution to hydroxylate small chain alkanes. Mutant AlkB-BMO1 hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. Mutant AlkB-BMO2 similarly hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. These biocatalysts are highly active for small chain alkane substrates and their regioselectivity is retained in whole-cell biotransformations.

  11. Hydroxyl free radical production during torsional phacoemulsification.

    Science.gov (United States)

    Aust, Steven D; Hebdon, Thomas; Humbert, Jordan; Dimalanta, Ramon

    2010-12-01

    To quantitate free radical generation during phacoemulsification using an ultrasonic phacoemulsification device that includes a torsional mode and evaluate tip designs specific to the torsional mode. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. Experimental study. Experiments were performed using the Infiniti Vision System and OZil handpiece. Hydroxyl radical concentrations in the aspirated irrigation solution during torsional phacoemulsification were quantitated as nanomolar malondialdehyde (nM MDA) and determined spectrophotometrically using the deoxyribose assay. The mean free radical production during phacoemulsification with torsional modality at 100% amplitude was 30.1 nM MDA ± 5.1 (SD) using a 0.9 mm 45-degree Kelman tapered ABS tip. With other tip designs intended for use with the torsional modality, free radical production was further reduced when fitted with the 0.9 mm 45-degree Kelman mini-flared ABS tip (13.2 ± 5.6 nM MDA) or the 0.9 mm 45-degree OZil-12 mini-flared ABS tip (14.3 ± 6.7 nM MDA). Although the measurements resulting from the use of the latter 2 tips were not statistically significantly different (P ≈ .25), they were different from those of the tapered tip (P<.0001). The MDA concentration in the aspirated irrigation solution using the torsional modality was approximately one half that reported for the handpiece's longitudinal modality in a previous study using the same bent-tip design (Kelman tapered, P<.0001). The level of MDA was further reduced approximately one half with torsional-specific tips. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  12. 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

  13. VizieR Online Data Catalog: Proper motions and photometry for members of Cha I (Esplin+, 2017)

    Science.gov (United States)

    Esplin, T. L.; Luhman, K. L.; Faherty, J. K.; Mamajek, E. E.; Bochanski, J. J.

    2017-10-01

    We have compiled a catalog of the previously known members of Cha I. We began with the census from Luhman 2008 (Cat. J/ApJ/675/1375). we adopt ChaJ11100159-7738052 as a previously known member, which was presented in Luhman 2007 (Cat. J/ApJS/173/104) as a possible field M9-L1 dwarf. We also include in our census the M9 companion to CT Cha (Schmidt et al. 2008A&A...491..311S) and five new M4 members from Frasca et al. 2015 (Cat. J/A+A/575/A4) and Sacco et al. 2017 (Cat. J/A+A/601/A97): 2MASSJ10575375-7724495, 2MASSJ10563146-7618334, 2MASSJ11213079-7633351, 2MASSJ11130450-7534369, and 2MASSJ11090915-7553477. We list the 244 previously known members and the 6 new members from this study in Table1. Luhman et al. (2005ApJ...635L..93L) obtained images of a 13.3'*16.7' area of the southern subcluster in Cha I with the Wide Field Camera (WFC) aperture of the Advanced Camera for Surveys (ACS) on board HST. The observations were performed on 2004 August 21 and 2005 February 16 with the F775W and F850LP filters. To measure proper motions for sources detected in those data, we repeated those observations in the F850LP filter on 2009 August 20 and 2011 February 13 through program 11695. Portions of Cha I have been imaged at several epochs with the Infrared Array Camera (IRAC) on Spitzer. Those observations occurred during both the cryogenic and post-cryogenic phases of the mission. The cryogenic phase began at launch in 2003 August and continued until 2009 May, when the liquid helium was depleted. During that time, IRAC operated with four 256*256 arrays that collected images in broadband filters at 3.6, 4.5, 5.8, and 8.0μm, which are denoted as [3.6], [4.5], [5.8], and [8.0]. For each array, the plate scale was 1.2''/pixel and the field of view (FOV) was 5.2'*5.2'. Point sources within the images have a FWHM of 1.6''-1.9'' for [3.6]-[8.0]. We compiled photometry from previous surveys for low-mass members of Cha I and publicly available catalogs, which consist of F775W and F850

  14. Magnetite-apatite-dolomitic rocks of Ust-Chulman (Aldan shield, Russia): Seligdar-type carbonatites?

    Science.gov (United States)

    Prokopyev, Ilya R.; Doroshkevich, Anna G.; Redina, Anna A.; Obukhov, Andrey V.

    2017-10-01

    The Ust-Chulman apatite ore body is situated within the Nimnyrskaya apatite zone at the Aldan shield in Russia. The latest data confirm the carbonatitic origin of the Seligdar apatite deposit (Prokopyev et al. in Ore Geol Rev 81:296-308, 2017). The results of our investigations demonstrate that the magnetite-apatite-dolomitic rocks of the Ust-Chulman are highly similar to Seligdar-type dolomitic carbonatites in terms of the mineralogy and the fluid regime of formation. The ilmenite and spinel mineral phases occur as solid solutions with magnetite, and support the magmatic origin of the Ust-Chulman ores. The chemical composition of REE- and SO3-bearing apatite crystals and, specifically, monazite-(Ce) mineralisation and the formation of Nb-rutile, late hydrothermal sulphate minerals (barite, anhydrite) and haematite are typical for carbonatite complexes. The fluid inclusions study revealed similarities to the evolutionary trend of the Seligdar carbonatites that included changes of the hydrothermal solutions from highly concentrated chloride to medium-low concentrated chloride-sulphate and oxidized carbonate-ferrous.

  15. Simultaneous incorporation of magnesium and carbonate in apatite: effect on physico-chemical properties

    Directory of Open Access Journals (Sweden)

    Marcia S. Sader

    2013-01-01

    Full Text Available Synthetic apatites are widely used both in the dental and the orthopaedic fields due to their similarity in composition with the inorganic phase of hard tissues. Biologic apatites are not pure hydroxyapatite (HA, but are calcium-deficient apatites with magnesium and carbonate as minor but important substituents. The aim of the present study was to produce a more soluble biomaterial through the simultaneous substitution of magnesium and carbonate in the apatite structure to accelerate the degradation time in the body. The physico-chemical and dissolution properties of unsintered magnesium and carbonate-substituted apatite (MCAp with similar Mg/Ca molar ratio (0.03 and varying C/P molar ratio were evaluated. The resultant powders were characterised using several techniques, such as FTIR, TGA, XRD, ICP and SEM, while the release of calcium ions in a pH 6 solution was monitored using a Ca-ion selective electrode. The results showed a decrease of crystallite size and an increase in the release of calcium to the medium as the carbonate content in the samples increased.

  16. Study of thermoluminescence properties of Eppawala apatite mineral and its suitability as a dosimetric material

    CERN Document Server

    Jayalath, A

    2000-01-01

    This study reports TL properties and the dosimetric properties of natural apatite mineral obtained from Eppawala Apatite ore in Sri Lanka. This mineral was used to study glow curve characteristics by using (a) the powder form of the raw mineral (b) sieved raw mineral and (c) the magnetically separated mineral. The glow curves of magnetically separated apatite showed two peaks. Low temperature peak at 120C, and a high temperature peak at 240C. The emission wavelength of the glow curve is 360 nm. The intensity of the 240C peak become stronger after annealing the mineral to about 180C. Apatite has glow peaks similar to other commonly used TL materials, such as synthetically prepared calcium sulphate:Dy and calcium sulphate:Tm show high intensity peak at 220C and low intensity peaks at 80C and 120C. However, the emission wavelengths of the main peaks are at 428nm and 452 nm for calcium sulphate:Dy and calcium sulphate: Tm respectively. Eppawala apatite mineral showed a linear response to both gamma and beta radia...

  17. Thermal transformations of the mineral component of composite biomaterials based on chitosan and apatite

    Energy Technology Data Exchange (ETDEWEB)

    Kalinkevich, O.V.; Kuznetsov, V.N.; Kalinkevich, A.N.; Kalinichenko, T.G.; Poddubny, I.N.; Sukhodub, L.F. [Institute for Applied Physics, Sumy (Ukraine); Starikov, V.V. [National Technical University ' ' Kharkov Polytechnic Institute' ' , Kharkov (Ukraine); Sklyar, A.M. [Sumy State Pedagogical University, Sumy (Ukraine); Danilchenko, S.N.

    2010-07-15

    Composite biomaterials based on chitosan and calcium apatite with different chitosan/apatite ratio were prepared by chemical synthesis of apatite in chitosan solution using one-step co-precipitation method. Initial and annealed samples were characterized by X-ray diffraction, FTIR spectroscopy and scanning electron microscopy coupled to energy-dispersive electron X-ray spectroscopy. The data obtained suggest that the formation of the calcium-phosphate mineral in chitosan solution is substantially modulated by the chemical interaction of the components; apparently, a part of calcium is captured by chitosan and does not participate in the formation of the main mineral phase. The apatite in the composite is calcium-deficient, carbonate-substituted and is composed of dispersed nano-sized crystallites, i.e. has properties that closely resemble those of bone mineral. Varying synthesis, drying and lyophilization conditions, the composite materials can be produced with the desirable chitosan/apatite ratio, both in the dense and porous form. The structural analysis of composite samples after annealing at certain temperatures is examined as an approach to elucidate the mechanism of co-precipitation by one-step method. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Textural study of the Puy Chopine trachytic eruption, Chaîne des Puys, France

    Science.gov (United States)

    Lit, Catherine; Gurioli, Lucia; van Wyk de Vries, Benjamin

    2016-04-01

    The Puy Chopine volcano (Quaternary Chaîne des Puys of the French Massif Central) has a trachytic spine, 160 m high and 500 m wide, in a crater formed by collapse of a scoria cone (Puy de Gouttes), during an explosive eruption with the same petrographic features as the spine. The proximal and distal pyroclastic deposits contain an array of fragments, both juvenile (vesiculated rhyolite pumice, fresh dense rhyolite fragments) and non juvenile (altered dense rhyolite, black scoria, granite, schist). Its complexity has perplexed early workers such as Scrope (1858). One explanation for the Chopine volcano eruption is (Boivin in 1983) that the intrusion of a trachyte magma underneath the Gouttes created a pheatomagmatic eruption, leaving a large crater or maar. A final spine was protruded. However, Boudon et al (2015) suggested that the Chopine could have formed from superficial dome explosions, formed at the onset of lava dome formation, where the impermeable carapace of an extruding magma built up significant overpressure to produce lateral explosions. In addition, van Wyk de Vries et al (2015) suggested that the Chopine first developed as a cryptodome, deforming the Gouttes as a 'crater of elevation', which collapsed to trigger shallow explosions from the exposed intrusion. We describe the textures of the Chopine dome and its explosive facies. Observations of a sequence deposited one km from the eruptive vent have identified at least six units linked to the Chopine eruptive sequence. The lowest gray layer is ~1 m thick, and is composed of accidental lithics and fresh dome materials. This layer is interpreted as a pyroclastic density current deposit with ballistics from the initial explosion. Juveniles vary from very dense to pumice-like, and can be tuff-like breccias. Most clasts are angular, except the non-juvenile and the breccia facies. Notable textural features are color-banding/lenses in some juvenile dense and vesicular samples. Inclusions of fluidal basalt

  19. Hydroxyl radical production in plasma electrolysis with KOH electrolyte solution

    Science.gov (United States)

    Saksono, Nelson; Febiyanti, Irine Ayu; Utami, Nissa; Ibrahim

    2015-12-01

    Plasma electrolysis is an effective technology for producing hydroxyl radical (•OH). This method can be used for waste degradation process. This study was conducted to obtain the influence of applied voltage, electrolyte concentration, and anode depth in the plasma electrolysis system for producing hydroxyl radical. The materials of anode and cathode, respectively, were made from tungsten and stainless steel. KOH solution was used as the solution. Determination of hydroxyl radical production was done by measuring H2O2 amount formed in plasma system using an iodometric titration method, while the electrical energy consumed was obtained by measuring the electrical current throughout the process. The highest hydroxyl radical production was 3.51 mmol reached with 237 kJ energy consumption in the power supply voltage 600 V, 0.02 M KOH, and 0.5 cm depth of anode.

  20. Hydroxyl radical production in plasma electrolysis with KOH electrolyte solution

    Energy Technology Data Exchange (ETDEWEB)

    Saksono, Nelson; Febiyanti, Irine Ayu, E-mail: irine.ayu41@ui.ac.id; Utami, Nissa; Ibrahim [Department of Chemical Engineering, Universitas Indonesia, Depok 16424, Indonesia Phone: +62217863516, Fax: +62217863515 (Indonesia)

    2015-12-29

    Plasma electrolysis is an effective technology for producing hydroxyl radical (•OH). This method can be used for waste degradation process. This study was conducted to obtain the influence of applied voltage, electrolyte concentration, and anode depth in the plasma electrolysis system for producing hydroxyl radical. The materials of anode and cathode, respectively, were made from tungsten and stainless steel. KOH solution was used as the solution. Determination of hydroxyl radical production was done by measuring H{sub 2}O{sub 2} amount formed in plasma system using an iodometric titration method, while the electrical energy consumed was obtained by measuring the electrical current throughout the process. The highest hydroxyl radical production was 3.51 mmol reached with 237 kJ energy consumption in the power supply voltage 600 V, 0.02 M KOH, and 0.5 cm depth of anode.

  1. Effect of curcumin against oxidation of biomolecules by hydroxyl radicals.

    Science.gov (United States)

    Borra, Sai Krishna; Mahendra, Jaideep; Gurumurthy, Prema; Jayamathi; Iqbal, Shabeer S; Mahendra, Little

    2014-10-01

    Among various reactive oxygen species, hydroxyl radicals have the strongest chemical activity, which can damage a wide range of essential biomolecules such as lipids, proteins, and DNA. The objective of this study was to investigate the beneficial effects of curcumin on prevention of oxidative damage of biomolecules by hydroxyl radicals generated in in vitro by a Fenton like reaction. We have incubated the serum, plasma and whole blood with H2O2/Cu2+/ Ascorbic acid system for 4 hours at 37 0C and observed the oxidation of biomolecules like albumin, lipids, proteins and DNA. Curcumin at the concentrations of 50,100 and 200 μmoles, prevented the formation of ischemia modified albumin, MDA, protein carbonyls, oxidized DNA and increased the total antioxidant levels and GSH significantly. These observations suggest the hydroxyl radical scavenging potentials of curcumin and protective actions to prevent the oxidation of biomolecules by hydroxyl radicals.

  2. Hydroxyl radical footprinting of protein-DNA complexes.

    Science.gov (United States)

    Jagannathan, Indu; Hayes, Jeffrey J

    2009-01-01

    This unit details the use of hydroxyl radicals to characterize protein-DNA interactions. This method may be used to assess the exact location of contacts between a protein and its cognate DNA and details of the complex structure. We describe several methods to prepare DNA templates for footprinting and ways to avoid many of the pitfalls associated with the use of hydroxyl radical footprinting. In addition, we describe in detail one example of the application of this technique.

  3. The CHA2DS2-VASc Score as a Predictor of Left Atrial Thrombus in Patients with Non-Valvular Atrial Fibrillation

    Science.gov (United States)

    Uz, Omer; Atalay, Murat; Doğan, Mehmet; Isilak, Zafer; Yalcin, Murat; Uzun, Mehmet; Kardesoglu, Ejder; Cebeci, Bekir Sitki

    2014-01-01

    Objective To investigate whether or not the CHA2DS2-VASc score predicts left atrial (LA) thrombus detected on pre-cardioversion transoesophageal echocardiography (TEE). Materials and Methods The medical records of patients who had undergone TEE were reviewed to assess the presence of LA thrombus prior to direct-current cardioversion for atrial fibrillation (AF). The CHA2DS2-VASc score was calculated for each patient. Clinical TEE reports were reviewed for the presence of LA thrombus. Patients with a valve prosthesis or rheumatic mitral valve disease were excluded from this study. Results A total of 309 patients were identified. The mean age was 70.1 ± 9.8 years and 151 (49%) patients were males and 158 (51%) were females. LA thrombus was seen in 32 (10.3%) of the 309 patients. Fifty (16.2%) patients had a low CHA2DS2-VASc score (0-1), 230 (74.4%) had an intermediate score (2-4) and 29 (9.4%) had a high score (5-9). The incidence of LA thrombus in the low, intermediate and high CHA2DS2-VASc score groups was 0, 4.4 and 68.7%, respectively. The LA thrombus risk increased with increasing CHA2DS2-VASc scores. On multivariate logistic analysis, the CHA2DS2-VASc score (OR 3.26, 95% CI 2.3-4.65; p = 0.001) and age (OR 0.93, 95% CI 0.88-0.98; p = 0.004) were independent risk factors for LA thrombus in patients with non-valvular AF. Conclusion A high CHA2DS2-VASc score was independently associated with the presence of LA thrombus in patients with non-valvular AF. PMID:24751402

  4. Enamel-like apatite crown covering amorphous mineral in a crayfish mandible

    Science.gov (United States)

    Bentov, Shmuel; Zaslansky, Paul; Al-Sawalmih, Ali; Masic, Admir; Fratzl, Peter; Sagi, Amir; Berman, Amir; Aichmayer, Barbara

    2012-01-01

    Carbonated hydroxyapatite is the mineral found in vertebrate bones and teeth, whereas invertebrates utilize calcium carbonate in their mineralized organs. In particular, stable amorphous calcium carbonate is found in many crustaceans. Here we report on an unusual, crystalline enamel-like apatite layer found in the mandibles of the arthropod Cherax quadricarinatus (freshwater crayfish). Despite their very different thermodynamic stabilities, amorphous calcium carbonate, amorphous calcium phosphate, calcite and fluorapatite coexist in well-defined functional layers in close proximity within the mandible. The softer amorphous minerals are found primarily in the bulk of the mandible whereas apatite, the harder and less soluble mineral, forms a wear-resistant, enamel-like coating of the molar tooth. Our findings suggest a unique case of convergent evolution, where similar functional challenges of mastication led to independent developments of structurally and mechanically similar, apatite-based layers in the teeth of genetically remote phyla: vertebrates and crustaceans. PMID:22588301

  5. The quantitative determination of calcite associated with the carbonate-bearing apatites

    Science.gov (United States)

    Silverman, Sol R.; Fuyat, Ruth K.; Weiser, Jeanne D.

    1951-01-01

    The CO2 combined as calcite in carbonate-bearing apatites as been distinguished from that combined as carbonate-apatite, or present in some form other than calcite, by use of X-ray powder patterns, differential thermal analyses, and differential solubility tests. These methods were applied to several pure apatite minerals, to one fossil bone, and to a group of phosphorites from the Phosphoria formation of Permian age from Trail Canyon and the Conda mine, Idaho, and the Laketown district, Utah. With the exceptions of pure fluorapatite, pure carbonate-flueorapatite, and one phosphorite from Trail Canyon, these substances contain varying amounts of calcite, but in all the samples an appreciable part of the carbonite content is not present as calcite. The results of solubility tests, in which the particle size of sample and the length of solution time were varied, imply that the carbonate content is not due to shielded calcite entrapped along an internal network of surfaces.

  6. 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.

  7. Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance

    Science.gov (United States)

    Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Zaitsev, Anatoly N.; Couëslan, Christopher; Xu, Cheng; Kynický, Jindřich; Mumin, A. Hamid; Yang, Panseok

    2017-03-01

    Apatite-group phosphates are nearly ubiquitous in carbonatites, but our understanding of these minerals is inadequate, particularly in the areas of element partitioning and petrogenetic interpretation of their compositional variation among spatially associated rocks and within individual crystals. In the present work, the mode of occurrence, and major- and trace-element chemistry of apatite (sensu lato) from calcite and dolomite carbonatites, their associated cumulate rocks (including phoscorites) and hydrothermal parageneses were studied using a set of 80 samples from 50 localities worldwide. The majority of this set represents material for which no analytical data are available in the literature. Electron-microprobe and laser-ablation mass-spectrometry data ( 600 and 400 analyses, respectively), accompanied by back-scattered-electron and cathodoluminescence images and Raman spectra, were used to identify the key compositional characteristics and zoning patterns of carbonatitic apatite. These data are placed in the context of phosphorus geochemistry in carbonatitic systems and carbonatite evolution, and compared to the models proposed by previous workers. The documented variations in apatite morphology and zoning represent a detailed record of a wide range of evolutionary processes, both magmatic and fluid-driven. The majority of igneous apatite from the examined rocks is Cl-poor fluorapatite or F-rich hydroxylapatite (≥ 0.3 apfu F) with 0.2-2.7 wt.% SrO, 0-4.5 wt.% LREE2O3, 0-0.8 wt.% Na2O, and low levels of other cations accommodated in the Ca site (up to 1000 ppm Mn, 2300 ppm Fe, 200 ppm Ba, 150 ppm Pb, 700 ppm Th and 150 ppm U), none of which show meaningful correlation with the host-rock type. Silicate, (SO4)2 - and (VO4)3 - anions, substituting for (PO4)3 -, tend to occur in greater abundance in crystals from calcite carbonatites (up to 4.2 wt.% SiO2, 1.5 wt.% SO3 and 660 ppm V). Although (CO3)2 - groups are very likely present in some samples, Raman micro

  8. Determination of rare earths and thorium in apatites by thermal and epithermal neutron-activation analysis.

    Science.gov (United States)

    Brunfelt, A O; Roelandts, I

    1974-06-01

    A procedure is described for the non-destructive determination of Na, Mn, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu and Th in apatites by thermal and epithermal neutron-activation of independent portions of the material. The method was applied to three apatites with different contents. The precision obtained was better than +/-5% for La, Ce, Sm, Eu, Gd, Tb and Dy and +/-20% for Yb, Nd, Ho, Er and Lu for an apatite with a total rare-earth oxide content of the order of 1%. Determination of Ce, Tb and Yb could only be carried out with thermal neutron-activation analysis, while Gd, Ho and Er could only be determined after irradiation with epithermal neutrons.

  9. Phenytoin-initiated hydroxyl radical formation: characterization by enhanced salicylate hydroxylation.

    Science.gov (United States)

    Kim, P M; Wells, P G

    1996-01-01

    Bioactivation of phenytoin and related teratogens by peroxidases such as prostaglandin H synthase (PHS) may initiate hydroxyl radical (.OH) formation that is teratogenic. Salicylate is hydroxylated by .OH at the third and fifth carbon atoms, forming 2,3- and 2,5-dihydroxybenzoic acids (DHBA). In vivo salicylate metabolism produces only the 2,5-isomer, so 2,3-DHBA formation may reflect .OH production. In the present study, we validated the salicylate assay using the known .OH generator paraquat and evaluated .OH production by phenytoin. Female CD-1 mice were treated with paraquat (30 mg/kg, intraperitoneally) given 30 min after acetylsalicylic acid (ASA) (200 mg/kg, intraperitoneally). Blood was collected at 5, 15, and 30 min and 1 and 2 hr after paraquat, and plasma was analyzed for DHBA isomers and glucuronide conjugates by high performance liquid chromatography with electrochemical detection. Paraquat increased 2,3-DHBA formation 19.2-fold, with substantial inter-individual variability in the time of maximal formation (p = 0.0001). The 2,3-DHBA glucuronide conjugates in vivo and in hepatic microsomal studies amounted to approximately 11% and 0.43%, respectively, of total 2,3-DHBA equivalents. To investigate putative .OH production initiated via PHS-catalyzed phenytoin bioactivation, ASA was given 30 min before phenytoin (65 or 100 mg/kg, intraperitoneally), resulting in respective 7.6-fold (p = 0.02) and 14.2-fold (p = 0.003) increases in phenytoin-initiated maximal 2,3-DHBA formation. Maximal 2,3-DHBA formation was 2.1-fold higher when ASA was administered after rather than before the same dose (65 mg/kg) of phenytoin (p = 0.03), indicating ASA inhibition of PHS-catalyzed phenytoin bioactivation. Urinary analysis was much less sensitive, and the 2,5-isomer reflected enzymatic rather than .OH-mediated hydroxylation. The paraquat studies demonstrate the importance of timing in accurately quantifying 2,3-DHBA formation and suggest that glucuronidation does not

  10. Determination of volatile concentrations in fluorapatite of Martian shergottite NWA 2975 by combining synchrotron FTIR, Raman spectroscopy, EMPA, and TEM, and inferences on the volatile budget of the apatite host-magma

    Science.gov (United States)

    SłAby, Ewa; Koch-Müller, Monika; FöRster, Hans-Jürgen; Wirth, Richard; Rhede, Dieter; Schreiber, Anja; Schade, Ulrich

    2016-02-01

    We combined the focused ion beam sample preparation technique with polarized synchrotron-based FTIR (Fourier transform infrared) spectroscopy, laser-Raman spectroscopy, electron microprobe analysis (EMPA), and transmission electron microscope (TEM) analysis to identify and quantify structurally bound OH, F, Cl, and CO3 groups in fluorapatite from the Northwest Africa 2975 (NWA 2975) shergottite. In this study, the first FTIR spectra of the OH-stretching region from a Martian apatite are presented that show characteristic OH-bands of a F-rich, hydroxyl-bearing apatite. Depending on the method of apatite-formula calculation and whether charge balance is assumed or not, the FTIR-based quantification of the incorporated OH, expressed as wt% H2O, is in variably good agreement with the H2O concentration calculated from electron microprobe data. EMP analyses yielded between 0.35 and 0.54 wt% H2O, and IR data yielded an average H2O content of 0.31 ± 0.03 wt%, consistent with the lower range determined from EMP analyses. The TEM observations implied that the volatiles budget of fluorapatite is magmatic. The water content and the relative volatile ratios calculated for the NWA 2975 magma are similar to those established for other enriched or intermediate shergottites. It is difficult to define the source of enrichment: either Martian wet mantle or crustal assimilation. Comparing the environment of parental magma generation for NWA 2975 with the terrestrial mantle in terms of water content, it displays a composition intermediate between enriched and depleted MORB.

  11. Adsorption of nucleotides on biomimetic apatite: The case of cytidine 5' monophosphate (CMP).

    Science.gov (United States)

    Choimet, Maëla; Tourrette, Audrey; Drouet, Christophe

    2015-10-15

    The chemical interaction between DNA macromolecules and hard tissues in vertebrate is of foremost importance in paleogenetics, as bones and teeth represent a major substrate for the genetic material after cell death. Recently, the empirical hypothesis of DNA "protection" over time thanks to its adsorption on hard tissues was revisited from a physico-chemical viewpoint. In particular, the existence of a strong interaction between phosphate groups of DNA backbone and the surface of apatite nanocrystals (mimicking bone/dentin mineral) was evidenced on an experimental basis. In the field of nanomedicine, DNA or RNA can be used for gene transport into cells, and apatite nanocarriers then appear promising. In order to shed some more light on interactions between DNA molecules and apatite, the present study focuses on the adsorption of a "model" nucleotide, cytidine 5' monophosphate (CMP), on a carbonated biomimetic apatite sample. The follow-up of CMP kinetics of adsorption pointed out the rapidity of interaction with stabilization reached within few minutes. The adsorption isotherm could be realistically fitted to the Sips model (Langmuir-Freundlich) suggesting the influence of surface heterogeneities and adsorption cooperativity in the adsorption process. The desorption study pointed out the reversible character of CMP adsorption on biomimetic apatite. This contribution is intended to prove helpful in view of better apprehending the molecular interaction of DNA fragments and apatite compounds, independently of the application domain, such as bone diagenesis or nanomedicine. This study may also appear informative for researchers interested in the origins of life on Earth and the occurrence and behavior of primitive biomolecules. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Biomimetic apatite formed on cobalt-chromium alloy: A polymer-free carrier for drug eluting stent.

    Science.gov (United States)

    Chen, Cen; Yao, Chenxue; Yang, Jingxin; Luo, Dandan; Kong, Xiangdong; Chung, Sung-Min; Lee, In-Seop

    2017-03-01

    In this study, sirolimus (SRL) was loaded within biomimetic apatite formed on cobalt-chromium (Co-Cr) alloy, which has been reported for the first time, to inhibit the in-stent restenosis. Two different groups of loading SRL within biomimetic apatite were prepared: Group A (mono-layer of apatite/SRL) and Group B (bi-layer of apatite/SRL). Group A and Group B showed the biphasic pattern of SRL release up to 40 and 90days, respectively. The attachment of human artery smooth muscle cell (HASMC) for both Group A and Group B was significantly inhibited, and proliferation dramatically decreased with the release of SRL. Noteworthily, biomimetic apatite alone also suppressed the SMC proliferation. The porous biomimetic apatite uniformly covered Co-Cr stent without crack or webbings. After balloon expansion, the integrity of biomimetic apatite was sufficient to resist delamination or destruction. Thus, this study demonstrated that biomimetic apatite is a promising drug carrier for potential use in stents. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. 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.

  14. A new glance at ruthenium sorption mechanism on hydroxy, carbonate, and fluor apatites: Analytical and structural studies.

    Science.gov (United States)

    Tõnsuaadu, K; Gruselle, M; Villain, F; Thouvenot, R; Peld, M; Mikli, V; Traksmaa, R; Gredin, P; Carrier, X; Salles, L

    2006-12-15

    The sorption mechanism of Ru3+ ions on hydroxy (HAp), carbonate (CO3HAp), and fluor apatites (FAp) has been studied in detail. Ru apatites were obtained by reaction of the apatites with RuCl3 in aqueous solution. The structure and composition of the ruthenium-modified apatites were studied by several techniques: elemental analysis, XRD, EXAFS, IR, NMR, SEM-EDS, TEM, and thermal analysis. The amount of Ru in the modified apatite varies from 7.8 to 10.5 wt% and is not related to the initial composition or the specific surface area of the apatite. The different characterization techniques show that in the Ru-modified apatites Ru is surrounded by six oxygen atoms and do not contain any chlorine. For Ru-HAp and Ru-CO3HAp the new phase is amorphous whereas it is crystalline for FAp. The catalytic oxidation ability is higher for Ru-HAp and Ru-CO3HAp compared to Ru-FAp apatite in the oxidation of benzylic alcohol.

  15. Formation of bone-like apatite on poly(L-lactic acid) fibers by a biomimetic process.

    Science.gov (United States)

    Yuan, X; Mak, A F; Li, J

    2001-10-01

    Bone-like apatite coating on poly(L-lactic acid) (PLLA) fibers was formed by immersing the fibers in a modified simulated body fluid (SBF) at 37 degrees C and pH 7.3 after hydrolysis of the fibers in water. The ion concentrations in SBF were nearly 1.5 times of those in the human blood plasma. The apatite was characterized by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thin-film X-ray diffraction, and Fourier transform infrared spectroscopy. After 15 days of incubation in SBF, an apatite layer with about 5-6 microm thickness was formed on the surface of the fibers. This apatite had a Ca/P ratio similar to that of natural bone. The mass of apatite coated PLLA fibers increased with extending the incubation time. After 20 days incubation, the fibers increased their mass by 25.8 +/- 2.1%. The apatite coating had no significant effect on the tensile properties of PLLA fibers. In this article, the bone-like apatite coating on three-dimensional PLLA braids was also studied. The motivation for this apatite coating was that it might demonstrate enhanced osteoconductivity in the future studies when they serve as biodegradable scaffolds in tissue engineering.

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

    Science.gov (United States)

    Yang, Jun; Yao, Zhiwen; Tang, Changyu; Darvell, B. W.; Zhang, Hualin; Pan, Lingzhan; Liu, Jingsong; Chen, Zhiqing

    2009-07-01

    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.

  17. 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.

  18. Genesis of apatite in the phosphatized limestones of the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Lamboy, M.

    mechanisms for the supply of phosphorus to the sea floor and the formation of phosphorites are yet to be resolved (see Bentor, 1980; Glenn et al., 1994a for review). The present day formation of apatite has been reported in both upwelling and weak.../non-upwell- ing regions (Baturin et al., 1972; Veeh et al., 1973; Heggie et al., 1990; Jahnke et al., 1983). Upwelling is only one factor and several other conditions are required in the process of apatite formation. Despite the occurrence of intense seasonal...

  19. Pacific Northwest National Laboratory Apatite Investigation at the 100-NR-2 Quality Assurance Project Plan

    Energy Technology Data Exchange (ETDEWEB)

    Fix, N. J.

    2008-03-28

    This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by staff working on the 100-NR-2 Apatite Project. The 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 would include apatite sequestration as the primary treatment, followed by a secondary treatment. The scope of this project covers the technical support needed before, during, and after treatment of the targeted subsurface environment using a new high-concentration formulation.

  20. Apatite: A New Tool For Understanding The Temporal Variability Of Magmatic Volatile Contents

    Science.gov (United States)

    Stock, M. J.; Humphreys, M.; Smith, V.; Pyle, D. M.; Isaia, R.

    2015-12-01

    The apatite crystal structure is capable of incorporating H2O, F and Cl, as well as trace CO2 and sulphur. These can be related to parental magma compositions through application of a series of pressure and temperature-dependent exchange reactions (Piccoli and Candela, 1994), permitting apatite crystals to preserve a record of all major volatile species in the melt. Furthermore, due to the general incompatibility of P in other rock-forming minerals, apatite is ubiquitous in igneous systems and often begins crystallising early, such that apatite inclusions within phenocrysts record melt volatile contents throughout magmatic differentiation. In this work, we compare the compositions of apatite inclusions and microphenocrysts with pyroxene-hosted melt inclusions from the Astroni 1 eruption of Campi Flegrei, Italy. 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 determine a time-series of magmatic volatile evolution in the build-up to eruption. 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 during ascent, due to rapid H diffusion through the phenocryst hosts (Woods et al., 2000). Given the rapid diffusivity of volatiles in apatite (Brenan, 1993), preservation of undersaturated compositions in microphenocrysts suggests that saturation was only achieved a few days to months before eruption and that it may have been the transition into a volatile-saturated state that ultimately triggered eruption. Piccoli and Candela, 1994. Am. J. of Sc., 294, 92-135. Gualda et al., 2012

  1. In Vitro Biocompability/Osteogenesis and In Vivo Bone Formation Evalution of Peptide-Decorated Apatite Nanocomposites Assisted via Polydopamine.

    Science.gov (United States)

    Deng, Yi; Sun, Yuhua; Bai, Yanjie; Gao, Xiang; Zhang, Huan; Xu, Anxiu; Huang, Enyi; Deng, Feng; Wei, Shicheng

    2016-04-01

    Enhancing the biocompatibility and osteogenic activity of nano-apatite for applications in bone graft substitutes and bone tissue engineering have been the current challenge in regeneration of lost bone. Inspired by mussels, here we have developed facile biomimetic approaches for preparation of two types of peptide-conjugated apatite nanocompsoties assisted by polydopamine (pDA). We exploited polydopamine chemistry for the modification of nano-apatite crystals: polydopamine coated apatite (HA-c-pDA) and polydopamine template-mediated apatite (HA-t-pDA), on which bone forming peptide was subsequently immobilized under weakly basic conditions to obtain peptide-conjugated apatite nanocomposites (HA-c-pep and HA-t-pep, respectively). TEM images revealed that HA-c-pDA displayed typically rod-like morphology, while HA-t-pDA was sponge-like structure where pDA sheets were decorated by needle-like apatite crystals with low degree of crystallinity. In the cell culture experiments, HA-t-pep nanocomposite exhibited higher cell proliferation, spreading, and alkaline phosphatase activity as well as calcium nodule-formation, compared with pristine nano-HA and HA-c-pep nanocomposite. We then implanted the peptide-decorated apatite into rabbit calvarial defects and analyzed bone formation after 2 months. The data revealed that HA-t-pep group exhibited remarkably enhanced bioactivity and bone formation in vivo. Based on these results, our biomimetic approach could be a promising tool to develop peptide-conjugated apatites for bone regeneration. Meanwhile, the excellent biocompatibility and high osteogenesis of the peptide-conjugated apatite nanocomposite might confer its great potentials in bone repair, bone augmentation, as well as coating of biomedical implants.

  2. Histopathology of fathead minnow (Pimephales promelas) exposed to hydroxylated fullerenes.

    Science.gov (United States)

    Jovanović, Boris; Whitley, Elizabeth M; Palić, Dušan

    2014-11-01

    Hydroxylated fullerenes are reported to be very strong antioxidants, acting to quench reactive oxygen species, thus having strong potential for important and widespread applications in innovative therapies for a variety of disease processes. However, their potential for toxicological side effects is still largely controversial and unknown. Effects of hydroxylated fullerenes C60(OH)24 on the fathead minnow (Pimephales promelas) were investigated microscopically after a 72-hour (acute) exposure by intraperitoneal injection of 20 ppm of hydroxylated fullerenes per gram of body mass. Cumulative, semi-quantitative histopathologic evaluation of brain, liver, anterior kidney, posterior kidney, skin, coelom, gills and the vestibuloauditory system revealed significant differences between control and hydroxylated fullerene-treated fish. Fullerene-treated fish had much higher cumulative histopathology scores. Histopathologic changes included loss of cellularity in the interstitium of the kidney, a primary site of haematopoiesis in fish, and loss of intracytoplasmic glycogen in liver. In the coelom, variable numbers of leukocytes, including many macrophages and fewer heterophils and rodlet cells, were admixed with the nanomaterial. These findings raise concern about in vivo administration of hydroxylated fullerenes in experimental drugs and procedures in human medicine, and should be investigated in more detail.

  3. How hydroxylation affects hydrogen adsorption and formation on nanosilicates

    Science.gov (United States)

    Kerkeni, Boutheïna; Bacchus-Montabonel, Marie-Christine; Bromley, Stefan T.

    2017-06-01

    Silicate dust constitutes one of the primary solid components of the Universe and is thought to be an essential enabler for complex chemistry in a number of astronomical environments. Hydroxylated silicate nanoclusters (MgO)x(SiO2)y(H2O)z, where strongly absorbed water molecules are dissociated on the silicate surface, are likely to be persistent in diffuse clouds. Such precursor species are thus also primary candidates as seeds for the formation and growth of icy dust grains in dense molecular clouds. Using density functional calculations we investigate the reactivity of hydroxylated pyroxene nanoclusters (Mg4Si4O12)(H2O)N (N = 1-4) towards hydrogen physisorption, chemisorption and H2 formation. Our results show that increased hydroxylation leads to a significant reduction in the energy range for the physisorption and chemisorption of single H atoms, when compared to bare silicate grains and bare bulk silicate surfaces. Subsequent chemisorption of a second H atom is, however, little affected by hydroxylation. The H2 reaction barrier for the recombination of two chemisorbed H atoms tends to follow a linear correlation with respect to the 2Hchem binding energy, suggestive of a general Brønsted-Evans-Polanyi relation for H2 formation on silicate grains, independent of dust grain size, composition and degree of hydroxylation.

  4. Ab initio dynamics of the cytochrome P450 hydroxylation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Elenewski, Justin E.; Hackett, John C, E-mail: jchackett@vcu.edu [Department of Physiology and Biophysics and The Massey Cancer Center, School of Medicine, Virginia Commonwealth University, 401 College Street, Richmond, Virginia 23219-1540 (United States)

    2015-02-14

    The iron(IV)-oxo porphyrin π-cation radical known as Compound I is the primary oxidant within the cytochromes P450, allowing these enzymes to affect the substrate hydroxylation. In the course of this reaction, a hydrogen atom is abstracted from the substrate to generate hydroxyiron(IV) porphyrin and a substrate-centered radical. The hydroxy radical then rebounds from the iron to the substrate, yielding the hydroxylated product. While Compound I has succumbed to theoretical and spectroscopic characterization, the associated hydroxyiron species is elusive as a consequence of its very short lifetime, for which there are no quantitative estimates. To ascertain the physical mechanism underlying substrate hydroxylation and probe this timescale, ab initio molecular dynamics simulations and free energy calculations are performed for a model of Compound I catalysis. Semiclassical estimates based on these calculations reveal the hydrogen atom abstraction step to be extremely fast, kinetically comparable to enzymes such as carbonic anhydrase. Using an ensemble of ab initio simulations, the resultant hydroxyiron species is found to have a similarly short lifetime, ranging between 300 fs and 3600 fs, putatively depending on the enzyme active site architecture. The addition of tunneling corrections to these rates suggests a strong contribution from nuclear quantum effects, which should accelerate every step of substrate hydroxylation by an order of magnitude. These observations have strong implications for the detection of individual hydroxylation intermediates during P450 catalysis.

  5. Histopathology of fathead minnow (Pimephales promelas) exposed to hydroxylated fullerenes

    Science.gov (United States)

    Whitley, Elizabeth M.; Palić, Dušan

    2014-01-01

    Hydroxylated fullerenes are reported to be very strong antioxidants, acting to quench reactive oxygen species, thus having strong potential for important and widespread applications in innovative therapies for a variety of disease processes. However, their potential for toxicological side effects is still largely controversial and unknown. Effects of hydroxylated fullerenes C60(OH)24 on the fathead minnow (Pimephales promelas) were investigated microscopically after a 72-hour (acute) exposure by intraperitoneal injection of 20 ppm of hydroxylated fullerenes per gram of body mass. Cumulative, semi-quantitative histopathologic evaluation of brain, liver, anterior kidney, posterior kidney, skin, coelom, gills and the vestibuloauditory system revealed significant differences between control and hydroxylated fullerene-treated fish. Fullerene-treated fish had much higher cumulative histopathology scores. Histopathologic changes included loss of cellularity in the interstitium of the kidney, a primary site of haematopoiesis in fish, and loss of intracytoplasmic glycogen in liver. In the coelom, variable numbers of leukocytes, including many macrophages and fewer heterophils and rodlet cells, were admixed with the nanomaterial. These findings raise concern about in vivo administration of hydroxylated fullerenes in experimental drugs and procedures in human medicine, and should be investigated in more detail. PMID:23883179

  6. Detrital zircon and apatite fission track data in the Liaoxi basins ...

    Indian Academy of Sciences (India)

    vation events in the northern margin of the North. China Craton (figure 1a). In this paper, detrital zircon and apatite fission track (AFT and ZFT) ages of the sedimentary rocks from the Liaoxi basins are presented. The purposes of this study are: • to study the geothermal status of the basins to understand lithosphere evolution;.

  7. Nanocellulose-collagen-apatite composite associated with osteogenic growth peptide for bone regeneration.

    Science.gov (United States)

    Saska, Sybele; Teixeira, Lucas Novaes; de Castro Raucci, Larissa Moreira Spinola; Scarel-Caminaga, Raquel Mantuaneli; Franchi, Leonardo Pereira; Dos Santos, Raquel Alves; Santagneli, Silvia Helena; Capela, Marisa Veiga; de Oliveira, Paulo Tambasco; Takahashi, Catarina Satie; Gaspar, Ana Maria Minarelli; Messaddeq, Younès; Ribeiro, Sidney José Lima; Marchetto, Reinaldo

    2017-10-01

    Despite advances in the field of biomaterials for bone repair/regeneration, some challenges for developing an ideal bone substitute need to be overcome. Herein, this study synthesized and evaluated in vitro a nanocomposite based on bacterial cellulose (BC), collagen (COL), apatite (Ap) and osteogenic growth peptide (OGP) or its C-terminal pentapeptide [OGP(10-14)] for bone regeneration purposes. The BC-COL nanocomposites were successfully obtained by carbodiimide-mediated coupling as demonstrated by spectroscopy analysis. SEM, FTIR and (31)P NMR analyses revealed that in situ synthesis to apatite was an effective route for obtaining of bone-like apatite. The OGP-containing (BC-COL)-Ap stimulated the early development of the osteoblastic phenotype. Additionally, the association among collagen, apatite, and OGP peptides enhanced cell growth compared with OGP-containing BC-Ap. Furthermore, none of the nanocomposites showed cytotoxic, genotoxic or mutagenic effects. These promising results suggest that the (BC-COL)-Ap associated with OGP peptides might be considered a potential candidate for bone tissue engineering applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The effect of crystallization of bioactive bioglass 45S5 on apatite formation and degradation.

    Science.gov (United States)

    Plewinski, Manja; Schickle, Karolina; Lindner, Markus; Kirsten, Armin; Weber, Michael; Fischer, Horst

    2013-12-01

    Amorphous bioglass 45S5 has been used for many years as bone substitute material. Bioactive glasses are also suitable as coating materials for implants in order to improve the bone ongrowth behavior. We hypothesize that both the apatite formation on the surface and the chemical stability can be improved by crystallization of the bioglass. Synthesized amorphous bioglass 45S5 specimens as well as samples which were crystallized at 1000 °C were stored in simulated body fluid for 1, 7, and 14 days. The respective apatite formation was gravimetrically determined and characterized by SEM and XRD analysis. Moreover, the degradation behavior was studied after storage in distilled water. The weight of the crystallized samples decreased 6.3% less than that of the amorphous samples. Calcium silica and calcium carbonate layers were found on amorphous bioglass after 7 and 14 days. However, apatite formation was observed only on the crystallized 45S5 samples after storage. We conclude that the chemical resistance can be improved and, in parallel, a pronounced apatite formation on the surface of 45S5 can be obtained by controlled crystallization of the material for the particular test setup. Therefore, crystallized bioactive glasses should be considered to be promising coating material for dental implants. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Magmatic origin of giant 'Kiruna-type' apatite-iron-oxide ores in central Sweden

    National Research Council Canada - National Science Library

    Jonsson, Erik; Troll, Valentin R; Högdahl, Karin; Harris, Chris; Weis, Franz; Nilsson, Katarina P; Skelton, Alasdair

    2013-01-01

    Iron is the most important metal for modern industry and Sweden is by far the largest iron-producer in Europe, yet the genesis of Sweden's main iron-source, the 'Kiruna-type' apatite-iron-oxide ores, remains enigmatic...

  10. 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.

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

    NARCIS (Netherlands)

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

  12. 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.

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

    Science.gov (United States)

    Wei, Jie; Wang, Jiecheng; Liu, Xiaochen; Ma, Jian; Liu, Changsheng; Fang, Jing; Wei, Shicheng

    2011-06-01

    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 3PO 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.

  14. Problematic Samples for Apatite (U-Th)/He Dating: Some Possible Causes and Solutions

    Science.gov (United States)

    Farley, K. A.

    2003-12-01

    Seven years of experience with (U-Th)/He dating reveals a subset of granites and gneisses (perhaps 10%) which yield apatites problematic for the method. Here I document these challenging samples and provide possible explanations and solutions. Rocks from some areas (e.g., Himalayas and Taiwan) tend to yield apatites in which every grain is broken, precluding accurate α emission correction. We developed a protocol in which the grain fragments are abraded to eliminate the α -ejection-affected surfaces. The now opaque fragments are immersed in appropriate refractive index oil, rendering inclusions remarkably visible for hand-picking. By eliminating the need to simultaneously have good morphology and freedom from inclusions, this technique greatly increases the population of datable grains. Results of a case study from Taiwan will be presented, as will modeling which shows how removal of outer edges must bias He ages, especially when cooling is slow. More problematic are seemingly good apatites that yield irreproducible and anomalously old He ages. The following observations apply to these rocks: strong geographic control, with problem samples common in some areas (e.g., Transantarctic Mtns) but absent elsewhere (e.g., Coast Mtns); highly variable U,Th among apatite grains (up to 2-3x); REEs (now measured on every dated apatite) have LREE depletion, compared with LREE enrichment in most non-problematic apatites. These observations are consistent with problematic apatites occurring preferentially in S-type granites, which have precipitated monazite (Sha and Chappell, 1999). Flux melting indicates that inclusions cannot explain the aberrant ages, and modeling and ion probe measurements suggest that U,Th zonation is not a likely cause either. A possible role for implantation of He from neighboring monazites is consistent with abrasion experiments yielding younger cores than obtained from whole grains. If this explanation is correct, it may be impossible to obtain

  15. The formation of Luoboling porphyry Cu-Mo deposit: Constraints from zircon and apatite

    Science.gov (United States)

    Li, Cong-ying; Hao, Xi-luo; Liu, Ji-qiang; Ling, Ming-xing; Ding, Xing; Zhang, Hong; Sun, Wei-dong

    2017-02-01

    The Luobuling porphyry Cu-Mo deposit belongs to the Late Cretaceous Zijinshan Cu-Au-Mo mineralization field in southeastern China. Due to intensive hydrothermal alteration and weathering, it is very difficult to collect fresh whole rock samples for geochemical and isotopic studies in Luobuling. Zircon and apatite are accessory minerals that are resistant to hydrothermal alterations. In this study, we compared the trace element and isotope compositions of zircon and apatite from ore-bearing and barren samples to understand the formation of the Luoboling Cu-Mo deposit. Zircon U-Pb LA-ICP-MS dating shows that the Luoboling porphyries formed at 100 Ma (100.3 ± 1.2 Ma, 100.6 ± 1.5 Ma and 98.6 ± 1.2 Ma), which belongs to the late stage mineralization of the Zijinshan mineralization field. Zhongliao porphyritic granodiorite has the same age as the deposit (99.5 ± 1.6 Ma). The age of barren Sifang granodiorite is slightly older (109.7 ± 0.8 Ma). All these zircon grains have high Ce4+/Ce3+ ratios, indicating high oxygen fugacities. The ore-bearing samples show variable εHf(t) of - 7.3 to 0.2, suggesting either heterogeneous sources or mixing of two different magmas. Interestingly, the Hf isotope composition of barren samples is systematically higher (εHf(t) of - 3.6 to 5.5), implying a lower contribution of crustal materials. The OH mole percent of apatite grains from barren samples (LBL22-03 and SF09-05) is 0.5, which is higher than that of apatite from the ore-bearing samples (LBL20-01 LBL20-02 and LBL22-02), indicating lower F, Cl contents or higher water contents in the magma. In apatite from the ore-bearing samples, Sr is high, indicating the absence of plagioclase crystallization. In contrast, barren samples have varied and lower Sr, indicating that apatite crystallization was accompanied by plagioclase. These patterns were controlled by water contents because the crystallization of plagioclase is suppressed by high water contents in magmas. It also suggests

  16. Bioconversion of Agave tequilana fructans by exo-inulinases from indigenous Aspergillus niger CH-A-2010 enhances ethanol production from raw Agave tequilana juice.

    Science.gov (United States)

    Huitrón, Carlos; Pérez, Rosalba; Gutiérrez, Luís; Lappe, Patricia; Petrosyan, Pavel; Villegas, Jesús; Aguilar, Cecilia; Rocha-Zavaleta, Leticia; Blancas, Abel

    2013-01-01

    Agave tequilana fructans are the source of fermentable sugars for the production of tequila. Fructans are processed by acid hydrolysis or by cooking in ovens at high temperature. Enzymatic hydrolysis is considered an alternative for the bioconversion of fructans. We previously described the isolation of Aspergillus niger CH-A-2010, an indigenous strain that produces extracellular inulinases. Here we evaluated the potential application of A. niger CH-A-2010 inulinases for the bioconversion of A. tequilana fructans, and its impact on the production of ethanol. Inulinases were analyzed by Western blotting and thin layer chromatography. Optimal pH and temperature conditions for inulinase activity were determined. The efficiency of A. niger CH-A-2010 inulinases was compared with commercial enzymes and with acid hydrolysis. The hydrolysates obtained were subsequently fermented by Saccharomyces cerevisiae to determine the efficiency of ethanol production. Results indicate that A. niger CH-A-2010 predominantly produces an exo-inulinase activity. Optimal inulinase activity occurred at pH 5.0 and 50 °C. Hydrolysis of raw agave juice by CH-A-2010 inulinases yielded 33.5 g/l reducing sugars, compared with 27.3 g/l by Fructozyme(®) (Novozymes Corp, Bagsværd, Denmark) and 29.4 g/l by acid hydrolysis. After fermentation of hydrolysates, we observed that the conversion efficiency of sugars into ethanol was 97.5 % of the theoretical ethanol yield for enzymatically degraded agave juice, compared to 83.8 % for acid-hydrolyzed juice. These observations indicate that fructans from raw Agave tequilana juice can be efficiently hydrolyzed by using A. niger CH-A-2010 inulinases, and that this procedure impacts positively on the production of ethanol.

  17. Arsenic in hydrothermal apatite: Oxidation state, mechanism of uptake, and comparison between experiments and nature

    Science.gov (United States)

    Liu, Weihua; Mei, Yuan; Etschmann, Barbara; Brugger, Joël; Pearce, Mark; Ryan, Chris G.; Borg, Stacey; Wykes, Jeremey; Kappen, Peter; Paterson, David; Boesenberg, Ulrike; Garrevoet, Jan; Moorhead, Gareth; Falkenberg, Gerald

    2017-01-01

    Element substitution that occurs during fluid-rock interaction permits assessment of fluid composition and interaction conditions in ancient geological systems, and provides a way to fix contaminants from aqueous solutions. We conducted a series of hydrothermal mineral replacement experiments to determine whether a relationship can be established between arsenic (As) distribution in apatite and fluid chemistry. Calcite crystals were reacted with phosphate solutions spiked with As(V), As(III), and mixed As(III)/As(V) species at 250 °C and water-saturated pressure. Arsenic-bearing apatite rims formed in several hours, and within 48 h the calcite grains were fully replaced. X-ray Absorption Near-edge Spectroscopy (XANES) data show that As retained the trivalent oxidation state in the fully-reacted apatite grown from solutions containing only As(III). Extended X-ray Fine Spectroscopy (EXAFS) data reveal that these As(III) ions are surrounded by about three oxygen atoms at an Assbnd O bond length close to that of an arsenate group (AsO43-), indicating that they occupy tetrahedral phosphate sites. The three-coordinated As(III)-O3 structure, with three oxygen atoms and one lone electron pair around As(III), was confirmed by geometry optimization using ab initio molecular simulations. The micro-XANES imaging data show that apatite formed from solutions spiked with mixed As(III) and As(V) retained only As(V) after completion of the replacement reaction; in contrast, partially reacted samples revealed a complex distribution of As(V)/As(III) ratios, with As(V) concentrated in the center of the grain and As(III) towards the rim. Most natural apatites from the Ernest Henry iron oxide copper gold deposit, Australia, show predominantly As(V), but two grains retained some As(III) in their core. The As-anomalous amphibolite-facies gneiss from Binntal, Switzerland, only revealed As(V), despite the fact that these apatites in both cases formed under conditions where As(III) is

  18. Electrocatalytic Properties of BDD Anodes: Its Loosely Adsorbed Hydroxyl Radicals

    Directory of Open Access Journals (Sweden)

    Nicolaos Vatistas

    2012-01-01

    Full Text Available The high oxidative action of boron doped diamond (BDD anodes on the biorefractory organic compounds has been attributed to the low adsorption of the generated hydroxyl radicals on the BDD surface in respect to other anodic materials. In a previous paper, the effect of low adsorption of BBD has been studied by proposing a continuum approach to represent the adsorption layer. The oxidative action of the hydroxyl radicals is attributed to the values of their diffusivity into the adsorption and adjacent reactive layer as well as to the value of kinetic constant in both layers. In this paper, more details on both layers are reported in order to justify the proposed continuum approach as well as the assumptions concerning diffusivity and kinetic constant in both adsorption and reactive layers, where the oxidative action of hydroxyl radicals occurs.

  19. Balloon borne LIDAR measurements of stratospheric hydroxyl radical

    Science.gov (United States)

    Heaps, W. S.; Mcgee, T. J.

    1983-01-01

    A balloon-borne laser radar (LIDAR) system for determining the stratospheric hydroxyl radical concentration constructed and flown by the Goddard Space Flight Center is discussed. The system measured hydroxyl in the altitude range of 34-37 km during an afternoon and early evening, producing the first post-sunset hydroxyl determination ever obtained. Daytime values (approximately 5 x 10 to the 6th/cu cm) are somewhat lower than previous measurements using in situ resonance fluorescence. Nighttime values (approximately 7 x 10 to the 5th/cu cm at 2100 CDT) are found to be higher than predicted by current one-dimensional models. Possible sources of these discrepancies, together with improvements possible in future systems, are outlined.

  20. Progress in stratospheric hydroxyl measurement by balloon-borne lidar

    Science.gov (United States)

    Heaps, W. S.; Mcgee, T. J.

    1985-01-01

    Knowledge of the concentration of hydroxyl radical is crucial to understanding the chemistry of the stratosphere. Hydroxyl participates in several catalytic cycles which destroy ozone and strongly influences the cycles of chlorine and nitrogen oxides by its reactions which form or destroy reservoirs for chlorine and odd-nitrogen compounds. Measurements have been conducted of the concentration of hydroxyl radical between the altitudes of 32.5 and 38.5 km using the technique of laser-induced fluorescence. The results ranging from 4 to 9 x 10 to the 6th per cu cm (with an accuracy of + or - 50 percent) are about 2-3 times lower than predicted by current one-dimensional models, although the uncertainties in the determination and in the models are sufficiently large to explain the differences. A number of potential improvements to the instrument are discussed.

  1. Characterization of the Ornithine Hydroxylation Step in Albachelin Biosynthesis

    Directory of Open Access Journals (Sweden)

    Kendra Bufkin

    2017-10-01

    Full Text Available N-Hydroxylating monooxygenases (NMOs are involved in siderophore biosynthesis. Siderophores are high affinity iron chelators composed of catechol and hydroxamate functional groups that are synthesized and secreted by microorganisms and plants. Recently, a new siderophore named albachelin was isolated from a culture of Amycolatopsis alba growing under iron-limiting conditions. This work focuses on the expression, purification, and characterization of the NMO, abachelin monooxygenase (AMO from A. alba. This enzyme was purified and characterized in its holo (FAD-bound and apo (FAD-free forms. The apo-AMO could be reconstituted by addition of free FAD. The two forms of AMO hydroxylate ornithine, while lysine increases oxidase activity but is not hydroxylated and display low affinity for NADPH.

  2. Hydroxyl Radical Dosimetry for High Flux Hydroxyl Radical Protein Footprinting Applications Using a Simple Optical Detection Method

    Science.gov (United States)

    Xie, Boer; Sharp, Joshua S.

    2015-01-01

    Hydroxyl radical protein footprinting (HRPF) by Fast Photochemical Oxidation of Proteins (FPOP) is a powerful benchtop tool used to probe protein structure, interactions, and conformational changes in solution. However, the reproducibility of all HRPF techniques is limited by the ability to deliver a defined concentration of hydroxyl radicals to the protein. This ability is impacted by both the amount of radical generated and the presence of radical scavengers in solution. In order to compare HRPF data from sample to sample, a hydroxyl radical dosimeter is needed that can measure the effective concentration of radical that is delivered to the protein, after accounting for both differences in hydroxyl radical generation and non-analyte radical consumption. Here, we test three radical dosimeters (Alexa Fluor 488, terepthalic acid, and adenine) for their ability to quantitatively measure the effective radical dose under the high radical concentration conditions of FPOP. Adenine has a quantitative relationship between UV spectrophotometric response, effective hydroxyl radical dose delivered, and peptide and protein oxidation levels over the range of radical concentrations typically encountered in FPOP. The simplicity of an adenine-based dosimeter allows for convenient and flexible incorporation into FPOP applications, and the ability to accurately measure the delivered radical dose will enable reproducible and reliable FPOP across a variety of platforms and applications. PMID:26455423

  3. Sulfur isotopic zoning in apatite crystals: A new record of dynamic sulfur behavior in magmas

    Science.gov (United States)

    Economos, Rita; Boehnke, Patrick; Burgisser, Alain

    2017-10-01

    The mobility and geochemical behavior of sulfur in magmas is complex due to its multi-phase (solid, immiscible liquid, gaseous, dissolved ions) and multi-valent (from S2- to S6+) nature. Sulfur behavior is closely linked with the evolution of oxygen fugacity (fO2) in magmas; the record of fO2 evolution is often enigmatic to extract from rock records, particularly for intrusive systems. We apply a novel method of measuring S isotopic ratios in zoned apatite crystals that we interpret as a record of open-system magmatic processes. We interrogate the S concentration and isotopic variations preserved in multiple apatite crystals from single hand specimens from the Cadiz Valley Batholith, CA via electron microprobe and ion microprobe. Isotopic variations in single apatite crystals ranged from 0 to 3.8‰ δ34S and total variation within a single hand sample was 6.1‰ δ34S. High S concentration cores yielded high isotopic ratios while low S concentration rims yielded low isotopic ratios. We discuss a range of possible natural scenarios and favor an explanation of a combination of magma mixing and open-system, ascent-driven degassing under moderately reduced conditions: fO2 at or below NNO+1, although the synchronous crystallization of apatite and anhydrite is also a viable scenario. Our conclusions have implications for the coupled S and fO2 evolution of granitic plutons and suggest that in-situ apatite S isotopic measurements could be a powerful new tool for evaluating redox and S systematics in magmatic systems.

  4. Effect of thermal treatment on apatite-forming ability of NaOH-treated tantalum metal.

    Science.gov (United States)

    Miyazaki, T; Kim, H M; Kokubo, T; Miyaji, F; Kato, H; Nakamura, T

    2001-08-01

    The prerequisite for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the body. This apatite can be reproduced on its surface even in an acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. The present authors previously showed that the tantalum metal subjected to a NaOH treatment to form a sodium tantalate hydrogel layer on its surface forms the bonelike apatite on its surface in SBF in a short period. The gel layer as-formed on the metal is, however, not resistant against abrasion, and hence thus-treated metal is not useful for clinical applications. In the present study, effects of thermal treatment on the mechanical properties and apatite-forming ability of the NaOH-treated tantalum metal were investigated. The sodium tantalate gel on the NaOH-treated tantalum was dehydrated to convert into amorphous sodium tantalate by a thermal treatment at 300 degrees C in air environment and into crystalline sodium tantalates by the thermal treatment at 500 degrees C. Resistivity of the gel layer against both peeling-off and scratching was significantly improved by the thermal treatment at 300 degrees C. The high apatite-forming ability of the sodium tantalate hydrogel was a little decreased by the thermal treatment at 300 degrees C, but appreciably decreased by the thermal treatment at 500 degrees C. It is believed that the tantalum metal subjected to the 0.5 M-NaOH treatment and the subsequent thermal treatment at 300 degrees C is useful as implants in dental and orthopaedic fields, since it shows high bioactivity as well as high fracture toughness. Copyright 2001 Kluwer Academic Publishers

  5. 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 guided by direct surface bonding rather than through stabilizing intermolecular interactions. Although standard οGads ° was estimated to only ⿿4 kJ/mol, the large value of Nmax led to significantly negative effective οGads values down to ⿿33 kJ/mol, reflecting the spontaneous character of adsorption process. Vibrational spectroscopy data (FTIR and Raman) pointed out spectral modifications upon adsorption, confirming chemical-like interactions where both the triphosphate group of ATP and its nucleic base were involved. The present study is intended to serve as a basis for future research works involving ATP and apatite nanocrystals/nanoparticles in view of biomedical applications (e.g. bone tissue engineering, intracellular drug delivery, ⿦).

  6. Thermal annealing of fission tracks in fluorapatite, chlorapatite, manganoanapatite, and Durango apatite: experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Ravenhurst, C.E.; Roden-Tice, M.K.; Miller, D.S. [Rensselaer Polytechnic Inst., Dept. of Earth and Environmental Sciences, Troy, New York (United States)]. E-mail: cravenhu@hotmail.com

    2003-07-01

    It is well known that the optically measured lengths of fission tracks in apatite crystals are a function of etching conditions, crystallographic orientation of the track, composition of the crystal, and the state of thermal annealing. In this study we standardize etching conditions and optimize track length measurability by etching until etch pits formed at the surface of each apatite crystal reached widths of about 0.74 {mu}m. Etching times using 5M HNO{sub 3} at 21{sup o}C were 31 s for Otter Lake, Quebec, fluorapatite; 47 s for Durango, Mexico, apatite; 33 s for Portland, Connecticut, manganoanapatite; and 11 s for Bamle, Norway, chlorapatite. An etching experiment using two etchant strengths (5M and 1.6M HNO{sub 3}) revealed that, despite significant differences in etch pit shape, fission-track length anisotropy with respect to crystallographic orientation of the tracks is not a chemical etching effect. A series of 227 constant-temperature annealing experiments were carried out on nuclear reactor induced tracks in oriented slices of the apatites. After etching, crystallographic orientations of tracks were measured along with their lengths. The 200-300 track lengths measured for each slice were ellipse-fitted to give the major (c crystallographic direction) and minor (a crystallographic direction) semi-axes used to calculate equivalent isotropic lengths. The equivalent isotropic length is more useful than mean length for thermal history analysis because the variation caused by anisotropy has been removed. Using normalized etching procedures and equivalent isotropic length data, we found that the fluorapatite anneals most readily, followed by Durango apatite, manganoanapatite, and lastly chlorapatite. (author)

  7. Influence of Common Bean (Phaseolus vulgaris) Grown in Elevated CO2 on Apatite Dissolution

    Science.gov (United States)

    Olsen, A. A.; Morra, B.

    2016-12-01

    We ran a series of experiments to test the hypothesis that release of plant nutrients contained in apatite will be accelerated by the growth of Langstrath Stringless green bean in the presence of atmospheric CO2 meant to simulate possible future atmospheric conditions due a higher demand of nutrients and growth rate caused by elevated CO2. We hypothesize that elevated atmospheric CO2 will lead to both increased root growth and organic acid exudation. These two traits will lead to improved acquisition of P derived from apatite. Experiments were designed to investigate the effect of these changes on soil mineral weathering using plants grown under two conditions, ambient CO2 (400ppm) and elevated CO2 (1000ppm). Plants were grown in flow-through microcosms consisting of a mixture of quartz and apatite sands. Mini-greenhouses were utilized to control CO2 levels. Plant growth was sustained by a nutrient solution lacking in Ca and P. Calcium and P content of the leachate and plant tissue served as a proxy for apatite dissolution. Plants were harvested biweekly during the eight-week experiment and analyzed for Ca and P to calculate apatite dissolution kinetics. Preliminary results suggest that approximately four times more P and Ca are present in the leachate from experiments containing plants under both ambient and elevated CO2 levels than in abiotic experiments; however, the amounts of both P and Ca released in experiments conducted under both ambient and elevated CO2 levels are similar. Additionally, the amount of P in plant tissue grown under ambient and elevated CO2 conditions is similar. Plants grown in elevated CO2 had a greater root to shoot ratio. The planted microcosms were found to have a lower pH than abiotic controls most likely due to root respiration and exudation of organic acids.

  8. Chaînes laser intenses à contraste élevé par amplification directe dans un milieu gazeux à excimères*

    Science.gov (United States)

    Uteza, O.; Tcheremiskine, V.; Clady, R.; Coustillier, G.; Gastaud, M.; Sentis, M.; Mikheev, L. D.; Chambaret, J. P.

    2006-12-01

    Cet article présente l'intérêt du concept de laser hybride (solide/gaz) et de l'amplification directe de puissance dans un milieu à excimères pour les chaînes laser de puissance ultrabrèves à contraste élevé. L'architecture d'une chaîne laser multiterawatt basée sur l'emploi du milieu amplificateur XeF(C-A) pompé par voie photolytique est ensuite détaillée, ainsi que les perspectives de dimensionnement de cette approche au niveau PWetEW.

  9. Hashish. Importance of the phenolic hydroxyl group in tetrahydrocannabinols.

    Science.gov (United States)

    Uliss, D B; Dalzell, H C; Handrick, G R; Howes, J F; Razdan, R K

    1975-02-01

    Optically active delta-3- and delta-8-tetrahydrocannabinols (THC's), cannabidiol and racemic delta-9-cis-THC, and their corresponding analogs (1b yields 4b) in which the positions of the phenolic hydroxyl group and the n-C5 side chain have been interchanged are compared in selected pharmacological tests in mice. the results indicate that the phenolic hydroxyl group in the 1 position in THC's is very important for eliciting activity and that cannabidiol and delta-9-cis-THC possess weak CNS depressant properties.

  10. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    Science.gov (United States)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Rácz, Gergely; Takács, Erzsébet; Wojnárovits, László

    2014-04-01

    Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV-vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved.

  11. Radiocarbon tracer measurements of atmospheric hydroxyl radical concentrations

    Science.gov (United States)

    Campbell, M. J.; Farmer, J. C.; Fitzner, C. A.; Henry, M. N.; Sheppard, J. C.

    1986-01-01

    The usefulness of the C-14 tracer in measurements of atmospheric hydroxyl radical concentration is discussed. The apparatus and the experimental conditions of three variations of a radiochemical method of atmosphere analysis are described and analyzed: the Teflon bag static reactor, the flow reactor (used in the Wallops Island tests), and the aircraft OH titration reactor. The procedure for reduction of the aircraft reactor instrument data is outlined. The problems connected with the measurement of hydroxyl radicals are discussed. It is suggested that the gas-phase radioisotope methods have considerable potential in measuring tropospheric impurities present in very low concentrations.

  12. [Hydrolysis of poly(L-lactic acid) fibers and formation of low crystalline apatite on their surface by a biomimetic process].

    Science.gov (United States)

    Yuan, Xiaoyan; Mak, Arthur F; He, Fei

    2003-09-01

    Low crystalline apatite coating was formed on the surface of biodegradable poly(L-lactic acid) (PLLA) fibers by a biomimetic process, i.e., by immersing the fibers in a modified simulated body fluid (SBF) at 37 degrees C and pH 7.3 after hydrolysis of the fibers in water. The apatite was characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. Results showed that the fiber hydrolysis could accelerate the apatite formation but had little effect on the chemical and crystalline structure of the apatite. The structure of the apatite coating formed by the biomimetic method was similar to that of apatite in the natural bone. The bone-like low crystalline apatite coating might exhibit enhanced osteo-conductivity when the PLLA fibers are applied in bone reconstruction biomaterials.

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

    OpenAIRE

    Ali Rostami; Marziyeh Bazamad; Behzad Hajalilou; Mohssen Moazzen

    2014-01-01

    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 ele...

  14. 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.

  15. The kinetics of the ordering of 13C-18O bonds in calcite and apatite

    Science.gov (United States)

    Stolper, D. A.; Halevy, I.; Eiler, J. M.

    2011-12-01

    Eiler and Schauble (2004) showed that the isotopes of C and O are not randomly distributed within single phases such as CO2 gas and carbonates, and in particular, that heavy isotopes of C and O tend to bond preferentially (clump) at lower temperatures. Consequently, the measurement of the deviation from a random distribution of C and O isotope distributions in a single phase can be used as a thermometer. As with other geothermometers based on homogeneous or heterogeneous equilibria, the clumped-isotope thermometer is susceptible to resetting (e.g., if the phase is reheated or experiences slow cooling). Thus, clumped-isotope "temperatures" of phases that have experienced complex thermal histories may, in fact, be closure temperatures, the interpretation of which requires quantification of the kinetics of redistribution of C and O isotopes as a function of temperature. These kinetics have received increasing attention (Dennis and Schrag, 2010; Passey 2010), and are likely to be critical for understanding clumped-isotope temperatures of samples that have been buried for long periods of time. To better constrain these kinetics we performed experiments on natural optical calcite from Mexico and carbonate-bearing apatite from the Siilinjarvi carbonatite (Finland). For each experiment, multiple single crystal grains (~2 mm in diameter) of calcite or apatite were loaded in open Pt capsules, pressurized with Ar gas, and held at 400-700 °C, 550 bars using a rapid quench TZM apparatus for 5 min to 520 hrs. After quenching, 13C-18O clumping was measured in the samples; the change from the initial Δ47 with time for each phase at each temperature was fit to simple mechanistic models of isotope exchange between sites in these phases. One conclusion of the experimental study is that resetting the internal ordering of carbonate groups proceeds more rapidly in calcites than in apatites. For example, heating apatite at 400 °C results in no change in clumping over a 24 hr period

  16. Hydroxyl radical reactivity at the air-ice interface

    Directory of Open Access Journals (Sweden)

    T. F. Kahan

    2010-01-01

    Full Text Available Hydroxyl radicals are important oxidants in the atmosphere and in natural waters. They are also expected to be important in snow and ice, but their reactivity has not been widely studied in frozen aqueous solution. We have developed a spectroscopic probe to monitor the formation and reactions of hydroxyl radicals in situ. Hydroxyl radicals are produced in aqueous solution via the photolysis of nitrite, nitrate, and hydrogen peroxide, and react rapidly with benzene to form phenol. Similar phenol formation rates were observed in aqueous solution and bulk ice. However, no reaction was observed at air-ice interfaces, or when bulk ice samples were crushed prior to photolysis to increase their surface area. We also monitored the heterogeneous reaction between benzene present at air-water and air-ice interfaces with gas-phase OH produced from HONO photolysis. Rapid phenol formation was observed on water surfaces, but no reaction was observed at the surface of ice. Under the same conditions, we observed rapid loss of the polycyclic aromatic hydrocarbon (PAH anthracene at air-water interfaces, but no loss was observed at air-ice interfaces. Our results suggest that the reactivity of hydroxyl radicals toward aromatic organics is similar in bulk ice samples and in aqueous solution, but is significantly suppressed in the quasi-liquid layer (QLL that exists at air-ice interfaces.

  17. Observational evidence for interhemispheric hydroxyl-radical parity

    NARCIS (Netherlands)

    Patra, P.K.; Krol, M.C.; Montzka, S.A.; Arnold, T.; Atlas, E.L.; Lintner, B.R.; Stephens, B.B.; Xiang, B.

    2014-01-01

    The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere1, 2, 3. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species

  18. Shrinkage of vitreous body caused by hydroxyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Park, Myoung Joo; Shimada, Takashi; Matuo, Yoichirou; Akiyama, Yoko; Izumi, Yoshinobu; Nishijima, Shigehiro [Osaka University, Osaka (Japan)

    2008-12-15

    In the study, we examined the effect of hydroxyl radical generated by {gamma}-ray and UV irradiation on shrinkage of vitreous body. Change in gel ratio of vitreous body and change in the properties of its components (collagen, sodium hyaluronate) were analyzed. By comparing these results, the amount of hydroxyl radical, which induces the considerable shrinkage of vitreous body, was evaluated from theoretical calculation based on experimental condition and some reported kinetic parameters. It was concluded that the integrated amount of hydroxyl radical required to liquefy half of the vitreous body (vitreous body gel ratio = 50%) was estimated as 140 {mu}molg{sup -1} from {gamma}-ray irradiation experiment. Also, from UV irradiation experiment result, it was confirmed that the effect of hydroxyl radical is larger than that of other reactive species. The causes of shrinkage of vitreous body are supposed as follows, 1) decrease in viscosity by cleavage of glycoside bond in sodium hyaluronate, 2) leaching of collagen from vitreous body and 3) leaching of crosslinked products and scission products of collagen.

  19. Enantioselective Hydroxylation of 4-Alkylphenols by Vanillyl Alcohol Oxidase

    NARCIS (Netherlands)

    Drijfhout, Falko P.; Fraaije, Marco W.; Jongejan, Hugo; Berkel, Willem J.H. van; Franssen, Maurice C.R.

    1998-01-01

    Vanillyl alcohol oxidase (VAO) from Penicillium simplicissimum catalyzes the enantioselective hydroxylation of 4-ethylphenol, 4-propylphenol, and 2-methoxy-4-propylphenol into 1-(4'-hydroxyphenyl)ethanol, 1-(4'-hydroxyphenyl)propanol, and 1-(4'-hydroxy-3'-methoxyphenyl)propanol, respectively, with

  20. Hydroxyl radical scavenging activity of peptide from sea cucumber ...

    African Journals Online (AJOL)

    enzyme complex, sea cucumber protein hydrolysis was carried out to obtain hydrolysates that have hydroxyl-radical-scavenging activity (HRSA). The hydrolytic process was monitored by HRSA and conditions for this process were optimized as follows: pH 6.5, temperature 35°C, 12 mg enzyme complex in a reaction solution ...

  1. Decomposition of water into highly combustible hydroxyl gas used in ...

    African Journals Online (AJOL)

    The method proposed involves the decomposition of water into highly combustible hydroxyl gas via electrolysis, which is used in internal combustion engines of electrical generators for electricity generation. The by-product obtained from combustion of this gas is water vapour and oxygen to replenish the atmosphere.

  2. Dioxygen reactivity of meso-hydroxylated hemes: intermediates in ...

    Indian Academy of Sciences (India)

    Keywords. Heme oxygenase; heme degradation; coupled oxidation; variable temperature paramagnetic NMR. Abstract. Heme oxygenase (HO) is the only enzyme in mammals known to catalyse the physiological degradation of unwanted heme into biliverdin, Fe ion and CO. The process involves introduction of the hydroxyl ...

  3. Biogenic hydroxyapatite (Apatite II™) dissolution kinetics and metal removal from acid mine drainage.

    Science.gov (United States)

    Oliva, J; Cama, J; Cortina, J L; Ayora, C; De Pablo, J

    2012-04-30

    Apatite II™ is a biogenic hydroxyapatite (expressed as Ca(5)(PO(4))OH) derived from fish bone. Using grains of Apatite II™ with a fraction size between 250 and 500 μm, batch and flow-through experiments were carried out to (1) determine the solubility constant for the dissolution reaction Ca(5)(PO(4))(3)(OH) ⇔ 5Ca(2+) + 3PO(4)(3-) + OH(-), (2) obtain steady-state dissolution rates over the pH range between 2.22 and 7.14, and (3) study the Apatite II™'s mechanisms to remove Pb(2+), Zn(2+), Mn(2+), and Cu(2+) from metal polluted water as it dissolves. The logK(S) value obtained was -50.8±0.82 at 25 °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 ≡PO(-), followed by a slow hydrolysis step, the dissolution rate dependence is expressed in mol m(-2) s(-1) as where Rate(25 °C) = -8.9 × 10(-10) × [9.96 × 10(5) × a(H+)]/[1 + 9.96 × 10(5) × a(H+)] where a(H+) is the proton activity in solution. Removal of Pb(2+), Zn(2+), Mn(2+) and Cu(2+) was by formation of phosphate-metal compounds on the Apatite II™ substrate, whereas removal of Cd(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™ that was designed to simulate the Apatite II™-metal polluted water interaction. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Human Dental Pulp Cells Responses to Apatite Precipitation from Dicalcium Silicates

    Directory of Open Access Journals (Sweden)

    Wei-Yun Lai

    2015-07-01

    Full Text Available Unraveling the mechanisms behind the processes of cell attachment and the enhanced proliferation that occurs as a response to the presence of calcium silicate-based materials needs to be better understood so as to expand the applications of silicate-based materials. Ions in the environment may influence apatite precipitation and affect silicate ion release from silicate-based materials. Thus, the involvement of apatite precipitate in the regulation of cell behavior of human dental pulp cells (hDPCs is also investigated in the present study, along with an investigation of the specific role of cell morphology and osteocalcin protein expression cultured on calcium silicate (CS with different Dulbecco’s modified Eagle’s medium (DMEM. The microstructure and component of CS cement immersion in DMEM and P-free DMEM are analyzed. In addition, when hDPCs are cultured on CS with two DMEMs, we evaluate fibronectin (FN and collagen type I (COL secretion during the cell attachment stage. The facilitation of cell adhesion on CS has been confirmed and observed both by scanning with an electron microscope and using immunofluorescence imaging. The results indicate that CS is completely covered by an apatite layer with tiny spherical shapes on the surface in the DMEM, but not in the P-free DMEM. Compared to the P-free DMEM, the lower Ca ion in the DMEM may be attributed to the formation of the apatite on the surfaces of specimens as a result of consumption of the Ca ion from the DMEM. Similarly, the lower Si ion in the CS-soaked DMEM is attributed to the shielding effect of the apatite layer. The P-free DMEM group releases more Si ion increased COL and FN secretion, which promotes cell attachment more effectively than DMEM. This study provides new and important clues regarding the major effects of Si-induced cell behavior as well as the precipitated apatite-inhibited hDPC behavior on these materials.

  5. Hydroxyl migration disorders the surface structure of hydroxyapatite nanoparticles

    Science.gov (United States)

    Cheng, Xiajie; Wu, Hong; Zhang, Li; Ma, Xingtao; Zhang, Xingdong; Yang, Mingli

    2017-09-01

    The surface structure of nano-hydroxyapatite (HAP) was investigated using a combined simulated annealing and molecular dynamics method. The stationary structures of nano-HAP with 4-7 nm in diameter and annealed under different temperatures were analyzed in terms of pair distribution function, structural factor, mean square displacement and atomic coordination number. The particles possess different structures from bulk crystal. A clear radial change in their atomic arrangements was noted. From core to surface the structures change from ordered to disordered. A three-shell model was proposed to describe the structure evolution of nano-HAP. Atoms in the core zone keep their arrangements as in crystal, while atoms in the surface shell are in short-range order and long-range disorder, adopting a typically amorphous structure. Atoms in the middle shell have small displacements and/or deflections but basically retain their original locations as in crystal. The disordered shell is about 1 nm in thickness, in agreement with experimental observations. The disordering mainly stems from hydroxyl migration during which hydroxyls move to the surface and bond with the exposed Ca ions, and their left vacancies bring about a rearrangement of nearby atoms. The disordering is to some extent different for particles unannealed under different temperatures, resulting from fewer number of migrated hydroxyls at lower temperatures. Particles with different sizes have similar surface structures, and their surface energy decreases with increasing size. Moreover, the surface energy is reduced by hydroxyl migration because the exposed Ca ions on the surface are ionically bonded with the migrated hydroxyls. Our calculations proposed a new structure model for nano-HAP, which indicates a surface structure with activities different from those without surface reorganization. This is particularly interesting because most bioactivities of biomaterials are dominated by their surface activity.

  6. Chaînes d'exploits scénarios de hacking avancés et prévention

    CERN Document Server

    Whitaker, Andrew; Voth, Jack B

    2009-01-01

    Un pirate informatique s'appuie rarement sur une unique attaque, mais utilise plutôt des chaînes d'exploits, qui impliquent plusieurs méthodes et attaques coordonnées, pour atteindre sa cible et arriver à ses fins. Ces chaînes d'exploits sont généralement complexes et difficiles à prévenir. Or la plupart des ouvrages de sécurité ne les couvrent pas, ou sinon de manière superficielle. Cet ouvrage présente en profondeur les principales chaînes d'exploits qui sévissent actuellement. À travers des exemples basés sur des stratégies d'attaques réelles, utilisant les outils actuels les plus courants et visant des cibles importantes comme des données bancaires ou de sécurité sociale, vous découvrirez le spectre complet des attaques, des réseaux sans-fil à l'accès physique en passant par l'ingénierie sociale. Dans chaque scénario, les exploits sont décortiqués un à un en vue d'expliquer la chaîne qui va conduire à l'attaque finale. Les mesures de prévention à appliquer pour éviter...

  7. Changes in the Composition of Raw Tea Leaves from the Korean Yabukida Plant during High-temperature Processing to Pan-Fried Kamairi-cha Green Tea

    Science.gov (United States)

    To develop a better understanding of compositional changes occurring during the production of commercial teas, we determined by high-performance liquid chromatography (HPLC) changes in ingredient levels during each of several manufacturing steps used to produce Kamairi-cha, a premium green tea. We ...

  8. CHADS2 and modified CHA2DS2-VASc scores for the prediction of congestive heart failure in patients with nonvalvular atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Yorihiko Koeda

    2017-10-01

    Conclusion: Calculation of the CHADS2 and mCHA2DS2-VASc scores in order to evaluate the risk of systemic thromboembolism was useful to predict the onset of CHF, but not all-cause death, in patients with NVAF.

  9. Prognosis in patients with atrial fibrillation and CHA2DS2-VASc Score = 0 in a community-based cohort study

    DEFF Research Database (Denmark)

    Taillandier, Sophie; Olesen, Jonas B; Clémenty, Nicolas

    2012-01-01

    Patients with atrial fibrillation (AF) and a CHA(2) DS(2) -VASc score = 0 have a very low risk of stroke and current guidelines even recommend no antithrombotic therapy to these patients. We investigated the rate and risk of adverse events and the impact of antithrombotic management in a community...

  10. CHADS2 and CHA2DS2-VASc score to assess risk of stroke and death in patients paced for sick sinus syndrome

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Nielsen, Jens Cosedis; Darkner, Stine

    2013-01-01

    The risk of stroke in patients with atrial fibrillation (AF) can be assessed by use of the CHADS2 and the CHA2DS2-VASc score system. We hypothesised that these risk scores and their individual components could also be applied to patients paced for sick sinus syndrome (SSS) to evaluate risk of str...

  11. Effect of surface silanol groups on the deposition of apatite onto silica surfaces: a computer simulation study

    CSIR Research Space (South Africa)

    Mkhonto, D

    2008-01-01

    Full Text Available Computer modelling techniques were employed to investigate the effect of surface silanol groups on the strength of adhesion of apatite thin films to silica surfaces. To this end, the researchers have studied a series of silica surfaces...

  12. Assessment of copper removal from highway stormwater runoff using Apatite II(TM) and compost : laboratory and field testing.

    Science.gov (United States)

    2015-03-01

    -Stormwater runoff introduces heavy metals to surface waters that are harmful to aquatic organisms, : including endangered salmon. This work evaluates Apatite II, a biogenic fish bone based adsorbent, for removing metal : from stormwater. The meta...

  13. Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu-U-Au-Ag Deposit, South Australia

    National Research Council Canada - National Science Library

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

    2017-01-01

    ...) iron-oxide copper gold (IOCG) ore system, South Australia. Moreover, hydrothermal apatite is a locally abundant mineral throughout the altered and mineralized rocks within and enclosing the deposit...

  14. MECHANISMS CONTROLLING Ca ION RELEASE FROM SOL-GEL DERIVED IN SITU APATITE-SILICA NANOCOMPOSITE POWDER

    National Research Council Canada - National Science Library

    Seyed Mohsen Latifi; Mohammadhossein Fathi; Varshosaz Jaleh; Ghochaghi Niloufar

    2015-01-01

    .... 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...

  15. 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

  16. L'usage des trachytes de la Chaîne des Puys dans l'antiquité

    OpenAIRE

    Miallier, Didier; Boivin, Pierre; Dousteyssier, Bertrand

    2011-01-01

    Rapport d'opération archéologique Opération de prospection thématique annuelle Opération archéologique n° 6889 Arrêté n° 2011-130; Un relevé 3D LiDAR du centre de la Chaîne des Puys, effectué en mars 2011 (Coordination Centre Régional Auvergnat de l'Information Géographique, CRAIG ; contrôle scientifique P. Labazuy, LMV-OPGC, UBP), a compris spécifiquement la zone du Kilian en haute résolution. Le fichier définitif a été livré au CRAIG au mois d'octobre 2011, suite à quoi il a été possible d'...

  17. Crystal Structure Studies of Human Dental Apatite as a Function of Age

    Directory of Open Access Journals (Sweden)

    Th. Leventouri

    2009-01-01

    Full Text Available Studies of the average crystal structure properties of human dental apatite as a function of age in the range of 5–87 years are reported. The crystallinity of the dental hydroxyapatite decreases with the age. The a-lattice constant that is associated with the carbonate content in carbonate apatite decreases with age in a systematic way, whereas the c-lattice constant does not change significantly. Thermogravimetric measurements demonstrate an increase of the carbonate content with the age. FTIR spectroscopy reveals both B and A-type carbonate substitutions with the B-type greater than the A-type substitution by a factor up to ~5. An increase of the carbonate content as a function of age can be deduced from the ratio of the 2CO3 to the 1PO4 IR modes.

  18. SAXS study of ion tracks in San Carlos olivine and Durango apatite

    Energy Technology Data Exchange (ETDEWEB)

    Afra, B., E-mail: baf109@physics.anu.edu.au [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Rodriguez, M.D. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Lang, M.; Ewing, R.C. [Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Kirby, N. [Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168 (Australia); Trautmann, C. [GSI Helmholtz Centre for Heavy Ion Research, Planckstrasse 1, Darmstadt D-64291 (Germany); Kluth, P. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

    2012-09-01

    Ion tracks were generated in crystalline San Carlos olivine (Mg,Fe){sub 2}SiO{sub 4} and Durango apatite Ca{sub 10}(PO{sub 4}){sub 6}F{sub 2} using different heavy ions ({sup 58}Ni, {sup 101}Ru, {sup 129}Xe, {sup 197}Au, and {sup 238}U) with energies ranging between 185 MeV and 2.6 GeV. The tracks and their annealing behavior were studied by means of synchrotron based small angle X-ray scattering in combination with in situ annealing. Track radii vary as a function of electronic energy loss but are very similar in both minerals. Furthermore, the annealing behavior of the track radii has been investigated and preliminary results reveal a lower recovery rate of the damaged area in olivine compared with apatite.

  19. Apatite 4He/3He and (U-Th)/He evidence for an ancient Grand Canyon.

    Science.gov (United States)

    Flowers, R M; Farley, K A

    2012-12-21

    The Grand Canyon is one of the most dramatic features on Earth, yet when and why it was carved have been controversial topics for more than 150 years. Here, we present apatite (4)He/(3)He thermochronometry data from the Grand Canyon basement that tightly constrain the near-surface cooling history associated with canyon incision. (4)He/(3)He spectra for eastern Grand Canyon apatites of differing He date, radiation damage, and U-Th zonation yield a self-consistent cooling history that substantially validates the He diffusion kinetic model applied here. Similar data for the western Grand Canyon provide evidence that it was excavated to within a few hundred meters of modern depths by ~70 million years ago (Ma), in contrast to the conventional model in which the entire canyon was carved since 5 to 6 Ma.

  20. X-ray diffraction patterns in human dentin, enamel and synthetic apatites related to Zn concentration.

    Science.gov (United States)

    Lappalainen, R; Knuuttila, M

    1981-12-01

    The crystallization of human dentin and enamel containing different concentrations of Zn was studied using X-ray diffraction analysis. The concentrations of Ca, Mg, Mn, Fe, Zn, Cu, Co, Ni, Sr and Pb in the samples were determined by atomic absorption spectrophotometry. The concentration of F was assayed with a combination fluoride electrode. The increase of the Zn concentration (microgram/g) from 150 to 572 in dentin was found to intensify apatite reflections indicating changes parallel to c-axis. A slight increase parallel to a-axis (or better crystallization) of lattices was demonstrated in both dentin and enamel. The increase of Zn concentration from 164 microgram/g to 692 microgram/g in enamel weakened 002 and 112 reflections. The effect of Zn on the crystallinity of synthetic apatite prepared at 37 degrees C was of the same kind as its effect on the dentin.

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

    OpenAIRE

    Abdillah Imron Nasution; Harun Asyiq Gunawan; Sri Angky Soekanto

    2013-01-01

    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 fluor...

  2. Biological evaluation of an apatite-mullite glass-ceramic produced via selective laser sintering.

    Science.gov (United States)

    Goodridge, Ruth D; Wood, David J; Ohtsuki, Chikara; Dalgarno, Kenneth W

    2007-03-01

    The biological performance of a porous apatite-mullite glass-ceramic, manufactured via a selective laser sintering (SLS) method, was evaluated to determine its potential as a bone replacement material. Direct contact and extract assays were used to assess the cytotoxicity of the material. A pilot animal study, implanting the material into rabbit tibiae for 4 weeks, was also carried out to assess in vivo bioactivity. The material produced by SLS did not show any acute cytotoxic effects by either contact or extract methods. There was no evidence of an apatite layer forming on the surface of the material when soaked in SBF for 30 days, suggesting that the material was unlikely to exhibit bioactive behaviour in vivo. It is hypothesized that the material was unable to form an apatite layer in SBF due to the fact that this glass-ceramic was highly crystalline and the fluorapatite crystal phase was relatively stable in SBF, as were the two aluminosilicate crystal phases. There was thus no release of calcium and phosphorus and no formation of silanol groups to trigger apatite deposition from solution within the test time period. Following implantation in rabbit tibiae for 4 weeks, bone was seen to have grown into the porous structure of the laser-sintered parts, and appeared to be very close to, or directly contacting, the material surface. This result may reflect the local environment in vivo compared to that artificially found with the in vitro SBF test and, furthermore, confirms previous in vivo data on these glass-ceramics.

  3. Diagenesis does not invent anything new: Precise replication of conodont structures by secondary apatite

    OpenAIRE

    Annalisa Ferretti; Daniele Malferrari; Luca Medici; Martina Savioli

    2017-01-01

    Conodont elements are important archives of sea/pore water chemistry yet they often exhibit evidence of diagenetic mineral overgrowth which may be biasing measurents. We decided to investigate this phenomenon by characterising chemically and crystallographically, the original biomineral tissue and the diagenetic mineral nature of conodont elements from the Ordovician of Normandy. Diagenetic apatite crystals observed on the surface of conodont elements show distinctive large columnar, blocky o...

  4. Effect of ion species on apatite-forming ability of silicone elastomer substrates irradiated by cluster ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Kawashita, Masakazu [Graduate School of Biomedical Engineering, Tohoku University, 6-6-11-1306-1 Aramaki-Aoba, Aoba-ku, Sendai 980-8579 (Japan)], E-mail: m-kawa@ecei.tohoku.ac.jp; Araki, Rei; Takaoka, Gikan H. [Photonics and Electronics Science and Engineering Center, Kyoto University (Japan)

    2009-04-15

    Indwelling catheters made of silicone elastomers sometimes cause serious infections owing to their poor biocompatibility. It is believed that these infections can be prevented by coating the silicone surface with apatite, which has excellent biocompatibility. If the surface of the silicone elastomer is in advance modified to have an apatite-forming ability, apatite can be coated on the modified silicone surface by soaking it in an aqueous solution such as a simulated body fluid (SBF) supersaturated with respect to apatite. In this study, silicone substrates were irradiated by four types of ion beams (Ar cluster, Ar cluster and monomer (Ar CM), O{sub 2} cluster, and O{sub 2} cluster and monomer (O{sub 2} CM) ion beams) at an acceleration voltage of 7 kV and a dose of 1 x 10{sup 15} ions/cm{sup 2}, and subsequently soaked in CaCl{sub 2} solution. The apatite-forming abilities of the substrates were examined using a metastable calcium phosphate solution whose ion concentration was 1.5 times that of SBF (1.5 SBF). Silicon oxide (SiO{sub x}) clusters were formed on the silicone surface and the hydrophilicity of the substrates was improved by the irradiation, irrespective of the ion species used. The irradiation with O{sub 2} CM ion beams resulted in the highest apatite-forming ability among the analyzed ion beams.

  5. Hanford 100-N Area In Situ Apatite and Phosphate Emplacement by Groundwater and Jet Injection: Geochemical and Physical Core Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Szecsody, James E.; Vermeul, Vincent R.; Fruchter, Jonathan S.; Williams, Mark D.; Rockhold, Mark L.; Qafoku, Nikolla; Phillips, Jerry L.

    2010-07-01

    The purpose of this study is to evaluate emplacement of phosphate into subsurface sediments in the Hanford Site 100-N Area by two different technologies: groundwater injection of a Ca-citrate-PO4 solution and water-jet injection of sodium phosphate and/or fish-bone apatite. In situ emplacement of phosphate and apatite adsorbs, then incorporates Sr-90 into the apatite structure by substitution for calcium. Overall, both technologies (groundwater injection of Ca-citrate-PO4) and water-jet injection of sodium phosphate/fish-bone apatite) delivered sufficient phosphate to subsur¬face sediments in the 100-N Area. Over years to decades, additional Sr-90 will incorporate into the apatite precipitate. Therefore, high pressure water jetting is a viable technology to emplace phosphate or apatite in shallow subsurface sediments difficult to emplace by Ca-citrate-PO4 groundwater injections, but further analysis is needed to quantify the relevant areal extent of phosphate deposition (in the 5- to 15-ft distance from injection points) and cause of the high deposition in finer grained sediments.

  6. Differential effects of collagen prolyl 3-hydroxylation on skeletal tissues.

    Directory of Open Access Journals (Sweden)

    Erica P Homan

    2014-01-01

    Full Text Available Mutations in the genes encoding cartilage associated protein (CRTAP and prolyl 3-hydroxylase 1 (P3H1 encoded by LEPRE1 were the first identified causes of recessive Osteogenesis Imperfecta (OI. These proteins, together with cyclophilin B (encoded by PPIB, form a complex that 3-hydroxylates a single proline residue on the α1(I chain (Pro986 and has cis/trans isomerase (PPIase activity essential for proper collagen folding. Recent data suggest that prolyl 3-hydroxylation of Pro986 is not required for the structural stability of collagen; however, the absence of this post-translational modification may disrupt protein-protein interactions integral for proper collagen folding and lead to collagen over-modification. P3H1 and CRTAP stabilize each other and absence of one results in degradation of the other. Hence, hypomorphic or loss of function mutations of either gene cause loss of the whole complex and its associated functions. The relative contribution of losing this complex's 3-hydroxylation versus PPIase and collagen chaperone activities to the phenotype of recessive OI is unknown. To distinguish between these functions, we generated knock-in mice carrying a single amino acid substitution in the catalytic site of P3h1 (Lepre1(H662A . This substitution abolished P3h1 activity but retained ability to form a complex with Crtap and thus the collagen chaperone function. Knock-in mice showed absence of prolyl 3-hydroxylation at Pro986 of the α1(I and α1(II collagen chains but no significant over-modification at other collagen residues. They were normal in appearance, had no growth defects and normal cartilage growth plate histology but showed decreased trabecular bone mass. This new mouse model recapitulates elements of the bone phenotype of OI but not the cartilage and growth phenotypes caused by loss of the prolyl 3-hydroxylation complex. Our observations suggest differential tissue consequences due to selective inactivation of P3H1 hydroxylase

  7. About the Genetic Mechanisms of Apatites: A Survey on the Methodological Approaches

    Directory of Open Access Journals (Sweden)

    Linda Pastero

    2017-08-01

    Full Text Available Apatites are properly considered as a strategic material owing to the broad range of their practical uses, primarily biomedical but chemical, pharmaceutical, environmental and geological as well. The apatite group of minerals has been the subject of a huge number of papers, mainly devoted to the mass crystallization of nanosized hydroxyapatite (or carboapatite as a scaffold for osteoinduction purposes. Many wet and dry methods of synthesis have been proposed. The products have been characterized using various techniques, from the transmission electron microscopy to many spectroscopic methods like IR and Raman. The experimental approach usually found in literature allows getting tailor made micro- and nano- crystals ready to be used in a wide variety of fields. Despite the wide interest in synthesis and characterization, little attention has been paid to the relationships between bulk structure and corresponding surfaces and to the role plaid by surfaces on the mechanisms involved during the early stages of growth of apatites. In order to improve the understanding of their structure and chemical variability, close attention will be focused on the structural complexity of hydroxyapatite (HAp, on the richness of its surfaces and their role in the interaction with the precursor phases, and in growth kinetics and morphology.

  8. Influence of fluoride in poly(d,l-lactide)/apatite composites on bone formation.

    Science.gov (United States)

    Luo, X; Barbieri, D; Passanisi, G; Yuan, H; de Bruijn, J D

    2015-05-01

    The influence of fluoride in poly(d,l-lactide)/apatite composites on ectopic bone formation was evaluated in sheep. Nano-apatite powders with different replacement levels of OH groups by fluoride (F) (0% (F0), 50% (F50), 100% (F100), and excessive (F200)) were co-extruded with poly (d,l-lactide) at a weight ratio of 1:1. Fluoride release from the composites (CF0, CF50, CF100, and CF200) was evaluated in vitro and bone formation was assessed after intramuscular implantation in sheep. After 24 weeks in simulated physiological solution, CF0 and CF50 showed negligible fluoride release, whereas it was considerable from the CF100 and CF200 composites. Histology showed that the incidence of de novo bone formation decreased in implants with increasing fluoride content indicating a negative influence of fluoride on ectopic bone formation. Furthermore, a significant decrease in resorption of the high fluoride-content composites and a reduction in the number of multinucleated giant cells were seen. These results show that instead of promoting, the presence of fluoride in poly(d,l-lactide)/apatite composites seemed to suppresses their resorption and osteoinductive potential in non-osseous sites. © 2014 Wiley Periodicals, Inc.

  9. 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.

  10. Composition Determination and Cathodoluminescence of Natural Apatite from Different Phosphate Deposits in Northern China

    Science.gov (United States)

    Guo, Qingfeng; Liao, Libing; Xia, Zhiguo; Liu, Haikun

    2014-06-01

    Two kinds of natural apatite minerals were obtained from two different phosphate deposits in northern China, FanShan, Hebei province and HeiYingShan, Inner Mongolia province. Their chemical compositions, phase structure, and cathodoluminescence (CL) have been comparatively investigated. X-ray diffraction (XRD) analysis indicated that the raw phosphate minerals from FanShan mainly are composed of FanShan apatite (FA) and FanShan mica, respectively, while the ore sample from HeiYingShan contained HeiYingshan apatite (HA) and HeiYingshan magnetite. The mineralogical characteristics and crystal structure of FA and HA were further determined by XRD, scanning electron microscopy, x-ray fluorescence spectrometer, and inductively coupled plasma-mass spectrometry, respectively. These results indicate that FA belongs to fluorapatite, while the HA belongs to hydroxyapatite. The existence of some trace elements has also been verified by the measured CL spectrum. The origin of the observed CL peaks has been discussed, and the relationship of the CL and the chemical composition has also been investigated.

  11. Influence of strontium for calcium substitution in bioactive glasses on degradation, ion release and apatite formation

    Science.gov (United States)

    Fredholm, Yann C.; Karpukhina, Natalia; Brauer, Delia S.; Jones, Julian R.; Law, Robert V.; Hill, Robert G.

    2012-01-01

    Bioactive glasses are able to bond to bone through the formation of hydroxy-carbonate apatite in body fluids while strontium (Sr)-releasing bioactive glasses are of interest for patients suffering from osteoporosis, as Sr was shown to increase bone formation both in vitro and in vivo. A melt-derived glass series (SiO2–P2O5–CaO–Na2O) with 0–100% of calcium (Ca) replaced by Sr on a molar base was prepared. pH change, ion release and apatite formation during immersion of glass powder in simulated body fluid and Tris buffer at 37°C over up to 8 h were investigated and showed that substituting Sr for Ca increased glass dissolution and ion release, an effect owing to an expansion of the glass network caused by the larger ionic radius of Sr ions compared with Ca. Sr release increased linearly with Sr substitution, and apatite formation was enhanced significantly in the fully Sr-substituted glass, which allowed for enhanced osteoblast attachment as well as proliferation and control of osteoblast and osteoclast activity as shown previously. Studying the composition–structure–property relationship in bioactive glasses enables us to successfully design next-generation biomaterials that combine the bone regenerative properties of bioactive glasses with the release of therapeutically active Sr ions. PMID:21993007

  12. Radiation damage studies of mineral apatite, using fission tracks and thermoluminescence techniques

    Energy Technology Data Exchange (ETDEWEB)

    Al-Khalifa, I.J.M. (Arabian Gulf Univ., Manama, Bahrain); James, K.; Durrani, S.A. (Birmingham Univ. (UK). Dept. of Physics); Khalifa, M.S. (Tajoura Research Centre, Tripoli (Libya))

    1988-01-01

    In a uranium (/thorium)-rich mineral sample which has not suffered a recent geological high-temperature excursion, the fossil fission track density (FFTD) will give a good indication of its natural radiation damage, provided that its U/Th ratio is known. From our studies of FFTD and thermoluminescence (TL) properties of several samples of apatite from different locations, and containing varying degrees of natural-radiation damage, an anti-correlation is observed between FFTD and TL sensitivity. It is also found that an anti-correlation exists between TL sensitivity and the amount of damage produced artificially by bombarding apatite crystals with different fluences of approx30 MeV alpha-particles from a cyclotron. These results indicate that the presence of radiation damage in this mineral (viz., fluorapatite) can severely affect its TL sensitivity (i.e. TL output per unit test dose). The effect of crystal composition on the thermoluminescence and fission track annealing properties of mineral apatite is also reported. We have found that fission track annealing sensitivity and TL sensitivity are both significantly lower in samples of chlorapatite than in samples consisting predominantly of fluorapatite. (author).

  13. 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.

  14. Diagenesis does not invent anything new: Precise replication of conodont structures by secondary apatite.

    Science.gov (United States)

    Ferretti, Annalisa; Malferrari, Daniele; Medici, Luca; Savioli, Martina

    2017-05-09

    Conodont elements are important archives of sea/pore water chemistry yet they often exhibit evidence of diagenetic mineral overgrowth which may be biasing measurents. We decided to investigate this phenomenon by characterising chemically and crystallographically, the original biomineral tissue and the diagenetic mineral nature of conodont elements from the Ordovician of Normandy. Diagenetic apatite crystals observed on the surface of conodont elements show distinctive large columnar, blocky or web-like microtextures. We demonstrate that these apatite neo-crystals exhibit the same chemical composition as the original fossil structure. X-ray microdiffraction has been applied herein for the first time to conodont structural investigation. Analyses of the entire conodont element surface of a variety of species have revealed the existence of a clear pattern of crystal preferred orientation. No significant difference in unit cell parameters was documented between the newly formed apatite crystals and those of the smooth conodont surfaces, thus it emerges from our research that diagenesis has strictly replicated the unit cell signature of the older crystals.

  15. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    Science.gov (United States)

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A regioselective alkylation at the C-6 hydroxyl group of erythromycin A-oxime derivatives

    OpenAIRE

    HOSANG MASTER; SINGH DHARMENDRA

    2005-01-01

    Erythromycin A contains five hydroxyl groups. The regioselective alkylation at the C-6 hydroxyl group was achieved to an extent ofmore than 97% when a 9-O-substituted erythromycin A-9-oxime was employed as the substrate.

  17. Orientation Dependent Polarized Micro-XAS Study of U, Th and Sr in Single Crystal Apatites

    Science.gov (United States)

    Luo, Y.; Rakovan, J.; Wright, S.

    2009-05-01

    In order to evaluate apatite as a potential solid nuclear waste form and a contaminant sequestration agent, the complimentary use of single crystal X-ray diffraction and X-ray absorption spectroscopy (XAS) is applied to the study of U, Th, and Sr doped apatite single crystals to investigate the site preference, oxidation state, and structural distortions created by these substituents. Single crystal X-ray diffraction provides average information regarding the site occupancy of U and Th in apatites. Extended X-ray absorption fine-structure (EXAFS) yields quantitative information of the local structure of these substituents, which includes near-neighbor distances, coordination numbers and variations in bond distances; while X-ray absorption near edge structure (XANES) is used to determine the oxidation states of U. Restricted by the typical small size (20-100 μm) and volume of our synthetic samples, Micro-XAS is required. Different from studies which take full advantage of the polarization of synchrotron radiation, our Micro- XAS study on single crystal apatites was hampered by the polarization effects. In order to extract precise information of valence state and structural variation from XAS, it is necessary to know the crystallographic orientation of the sample with respect to the polarization direction of the incident X-ray beam during data collection. To do this we have designed and built a portable goniometer that duplicates the geometry of our laboratory standard Bruker Apex diffractometer goniometer. Crystal orientation is determined by X-ray diffraction at our home institution. The portable goniometer is then set up on the experimental table at synchrotron facilities and the crystal can be set in any specific known orientation. The lattice orientation determined by X-ray diffraction is applied to XAS data analysis, specifically calculation of scattering amplitudes and phase shifts, to account for polarization effects of synchrotron radiation. The goniometer

  18. Hydroxyl accessibility in wood by deuterium exchange and ATR-FTIR spectroscopy

    DEFF Research Database (Denmark)

    Tarmian, Asghar; Burgert, Ingo; Thybring, Emil Engelund

    2017-01-01

    The accessibility of wood hydroxyls to water is commonly studied by infrared spectroscopy after deuteration where water-interacting hydroxyls have their H exchanged for D. In this study, the hydroxyl accessibility is determined with ATR-FTIR spectroscopy after deuteration of specimens with liquid D...

  19. Third-generation FAGE instrument for tropospheric hydroxyl radical measurement

    Science.gov (United States)

    Chan, C. Y.; Hard, T. M.; Mehrabzadeh, A. A.; George, L. A.; O'Brien, R. J.

    1990-01-01

    A single-stage, frequency-doubled, copper vapor laser-pumped dye laser has been constructed to be used in the measurement of atmospheric hydroxyl radical concentrations. A new photon counting instrument is used for HO fluorescence detection. Theoretical and experimental studies of instrument performance show better sensitivities and reduced photolytic interferences than have been possible with previous systems based upon Nd:YAG pumping.

  20. The Haber Process Made Efficient by Hydroxylated Graphene

    OpenAIRE

    Chaban, Vitaly; Prezhdo, Oleg

    2016-01-01

    The Haber-Bosch process is the main industrial method for producing ammonia from diatomic nitrogen and hydrogen. Very demanding energetically, it uses an iron catalyst, and requires high temperature and pressure. Any improvement of the Haber process will have an extreme scientific and economic impact. We report a significant increase of ammonia production using hydroxylated graphene. Exploiting the polarity difference between N2/H2 and NH3, as well as the universal proton acceptor behavior of...

  1. Chemistry of azopyrimidines. Part IV¦. Aromatic hydroxylation in ...

    Indian Academy of Sciences (India)

    A single Pd-Cl stretch at 360 cm-1 supports the composition of phenolato complex. Unlike Pd(aapm)Cl2 the hydroxylated product, Pd(aapmO)Cl, has a structured intense absorption in the visible region near 670 nm. The Pd-Cl bond in Pd(aapmO)Cl is highly sensitive to nucleophilic substitution and slowly hydrolyses in ...

  2. Polydopamine Generates Hydroxyl Free Radicals under Ultraviolet-Light Illumination.

    Science.gov (United States)

    Wang, Zehuan; Tang, Feng; Fan, Hailong; Wang, Le; Jin, Zhaoxia

    2017-06-13

    Polydopamine (PDA) generally demonstrates as an efficient free-radical scavenger. However, its free-radical chemistry under illumination is unclear, which becomes important in view of growing studies of polydopamine applications in photoprotector and photothermal therapy. In this study, for the first time, we reported an experimental investigation of the generation of hydroxyl free radicals from ultraviolet (UV)-illuminated polydopamine in an aqueous environment. By using terephthalic acid as fluorescent probe, we measured hydroxyl radicals generated from UV-illuminated polydopamine with different shapes and sizes. The morphology of PDA shows significant influence on its productions of hydroxyl free radicals. Through characterizations of UV-vis absorption spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectrometry, mass spectrometry, and thermogravimetric analysis, we demonstrated the change of PDA nanomaterials brought by UV-light illumination in composition and thermal stability. We proposed a tentative mechanism for interpreting the relationship between morphology and photostability of PDA nanomaterials. These results reveal underlying complexity of polydopamine chemistry under light illumination that will deepen our understanding and benefit its further application.

  3. Synthesis and properties evaluation of sulfobetaine surfactant with double hydroxyl

    Science.gov (United States)

    Zhou, Ming; Luo, Gang; Zhang, Ze; Li, Sisi; Wang, Chengwen

    2017-09-01

    A series of sulfobetaine surfactants {N-[(3-alkoxy-2-hydroxyl)propoxy] ethyl-N,N-dimethyl-N-(2-hydroxyl)propyl sulfonate} ammonium chloride were synthesized with raw materials containing linear saturated alcohol, N,N-dimethylethanolamine, sodium 3-chloro-2-hydroxyl propane sulfonic acid and epichlorohydrin. The molecule structures of sulfobetaine surfactants were characterized by FTIR, 1HNMR and elemental analysis. Surface tension measurements can provide us information about the surface tension at the CMC (γCMC), pC20, Γmax and Amin. The pC20 values of sulfobetaine surfactants increase with the hydrophobic chain length increasing. Amin values of the surfactants decrease with increasing hydrophobic chain length from 10 to 14. The critical micelle concentration (CMC) and surface tension (γCMC) values of the sulfobetaine surfactants decrease with increasing hydrophobic chain length from 10 to 16. The lipophilicity of surfactant was enhanced with the increase of the carbon chain, however, the ability of anti-hard water was weakened. The minimum oil/water interfacial tension of four kinds of sulfobetaine surfactants is 10-2-10-3 mN/m magnitude, which indicates that the synthesized bis-hydroxy sulfobetaine surfactants have a great ability to reduce interfacial tension in the surfactant flooding system. The surface tension (γCMC) values of synthesized surfactants were lower compared with conventional anionic surfactant sodium dodecyl sulfonate.

  4. Rare earth elements in apatite as a monitor of magmatic and metasomatic processes: The Ilímaussaq complex, South Greenland

    Science.gov (United States)

    Zirner, Aurelia L. K.; Marks, Michael A. W.; Wenzel, Thomas; Jacob, Dorrit E.; Markl, Gregor

    2015-07-01

    Textural and compositional variations of apatite from the plutonic Ilímaussaq complex in South Greenland and its surrounding country rocks track magmatic and metasomatic processes. Detailed back-scattered electron (BSE) imaging reveals various types of apatite textures including (i) growth zonation (concentric, oscillatory as well as sector zonation) formed during magmatic differentiation, (ii) resorption and overgrowth textures due to fluid/melt induced metasomatic overprint of precursor apatite and (iii) replacement textures indicating the destabilization of apatite in favor of monazite. In the least evolved rocks of the Ilímaussaq complex, apatite incorporates rare earth elements and Y (REY) mainly via the coupled substitution Ca2 + + P5 + = REY3 + + Si4 +. In the more evolved peralkaline rocks and in metasomatically overprinted rocks, however, the coupled substitution 2 Ca2 + = REY3 + + Na+ becomes increasingly relevant, and apatite incorporates successively more LREE compared to HREE as shown by increasing (La/Gd)N and (Gd/Yb)N ratios. Similarly, at the contact between the Ilímaussaq rocks and the granitic country rocks, the metasomatic effect of the emplacement of the Ilímaussaq melts is preserved in partly resorbed precursor apatite, which is overgrown by REY-enriched apatite with higher (La/Gd)N and (Gd/Yb)N ratios compared to apatite from granites more distant from the contact. This study shows, that apatite textures and compositions are suitable to track both primary magmatic and later fluid-present metasomatic processes. The incorporation of REY in apatite is not only dependent on the amount of REY present but also depends largely on Na activity in the apatite-precipitating melts and fluids.

  5. The tetrad effect and geochemistry of apatite from the Altay Koktokay No. 3 pegmatite, Xinjiang, China: implications for pegmatite petrogenesis

    Science.gov (United States)

    Cao, Ming-Jian; Zhou, Qi-Feng; Qin, Ke-Zhang; Tang, Dong-Mei; Evans, Noreen J.

    2013-12-01

    In order to better constrain the evolution and petrogenesis of pegmatite, geochemical analysis was conducted on a suite of apatite crystals from the Altay Koktokay No. 3 pegmatite, Xinjiang, China and from the granitic and amphibolitic wall rocks. Apatite samples derived from pegmatite zones show convex tetrad effects in their REE patterns, extremely negative Eu anomalies and non-chondritic Y/Ho ratios. In contrast, chondritic Y/Ho ratios and convex tetrad effects are observed in the muscovite granite suggesting that different processes caused non-chondritic Y/Ho ratios and lanthanide tetrad effects. Based on the occurrence of convex tetrad effects in the host rocks and their associated minerals, we propose that the tetrad effects are likely produced from immiscible fluoride and silicate melts. This is in contrast to previous explanations of the tetrad effect; i.e. surface weathering, fractional crystallization and/or fluid-rock interaction. Additionally, we put forward that extreme negative Eu and non-chondritic Y/Ho in apatite are likely caused by the large amount of hydrothermal fluid exsolved from the pegmatite melts. Evolution of melt composition was found to be the primary cause of inter and intra-crystal major and trace element variations in apatite. Mn entering into apatite via substitution of Ca is supported by the positive correlation between CaO and MnO. Different evolution trends in apatite composition imply different crystallization environments between wall rocks and pegmatite zones. Based on the geochemistry of apatite samples, it is likely that there is a genetic relationship between the source of muscovite granite and the source of the pegmatite.

  6. Lithogeochemical, mineralogical analyses and oxygen-hydrogen isotopes of the Hercynian Koudiat Aïcha massive sulphide deposit, Morocco

    Science.gov (United States)

    Lotfi, F.; Belkabir, A.; Brunet, S.; Brown, A. C.; Marcoux, E.

    2010-03-01

    Koudiat Aïcha is a Visean stratiform, volcanogenic massive sulphide (VMS) zinc-copper-lead deposit, situated northwest of Marrakech, within the Central Domain of the Jebilet massif of the Western Moroccan Meseta. The Central Domain is formed mainly of sedimentary (argillite, siltstone, sandstone, carbonate) and magmatic (gabbro and rhyodacite) rocks that host numerous massive sulphide deposits (e.g., Koudiat Aïcha, Kettara and Draa Sfar) in a thick grayish argillite sequence (rhythmic metapelite). The deposit is stratabound and consists of highly deformed, sheet-like lenses of massive sulphide located structurally on the eastern flank of a large anticline. Prior to metamorphism, the country rocks were subjected to hydrothermal alteration which is particularly pronounced in the immediate vicinity of the sulphide deposits where chloritization and sericitization are prevalent. Hydrothermal alteration extends into both the stratigraphic footwall and the stratigraphic hanging wall. The footwall lacks an obvious pipe zone (sulphide stringers or vent complex) beneath the sulphide mineralization, but is characterized by an increase in the modal proportion of Mg-chlorite and by the breakdown of feldspar and sericite. Chloritization, the most extensive and readily recognizable alteration useful in mineral exploration, is evident for more than 60 m above the subcropping sulphide deposits. The hanging wall rocks show a pervasive sericitization (over 30 m wide) and a weak chlorite alteration accompanied by disseminated nodules of pyrrhotite stretched parallel to the S 1 foliation. Because chlorite and sericite are metamorphic minerals that also occur in unaltered rocks surrounding the sulphide deposits, abundant Mg-rich chlorite and the absence of feldspar in the footwall are used to distinguish hydrothermal alteration facies from metamorphic facies. The chlorite geothermometer reveals temperatures between 250 and 330 °C. Higher temperatures (up to 300 °C) are associated

  7. The Chaîne des Puys and Limagne Fault World Heritage project: a view from a scientist

    Science.gov (United States)

    van Wyk de Vries, B.

    2013-12-01

    The development of the Chaîne des Puys and Limagne Fault World Heritage UNESCO project has taken about five years, since the Laboratoire Magmas et Volcans was approached by the local Auvergne government. Before this we had been working locally with organisations such as the Lemptégy volcano and Vulcania to help disseminate geoscience ideas to the general public, however the UNESCO project has lead us to do much more outreach. It has also stimulated our research and has taught us to better explain this to the lay person. In visiting other heritage projects, where we have exchanged ideas and best practice, we have been able to help other sites and improve what we do. These links are particularly important, as they can be used to help broaden the outlook of the general public and local actors, and increase further earth science literacy. I have noticed a strong increase in the awareness of the volcanoes, and volcanism as a result of the Chaîne des Puys and Limagne Fault project. I think that, before, many locals considered the volcanoes only as their special back garden, for easy walks and views and leisure, or for that matter farming, mining and hunting. However, now, there is a greater sense of pride rooted in the increased awareness of their geological significance in a historical and global context. While this effect is clear for the volcanoes, it is not yet apparent for the fault. The lay person has no clear concept of a rift and a fault. Thus, one of our major present challenges is to open the public's eyes to the fault. This is vital for the UNESCO project not only for educational reasons, but also because the fault scarp is a natural barrier that protects the rest of the property from urban development. Only if there is awareness of its nature and significance will it be an effective defence. To arrive at this goal, there is now a local government sponsored project to create and disseminate fault walks, fault viewpoints and fault information points. This is

  8. Apatite 4He/3He thermochronometry evidence for an ancient Grand Canyon, Colorado Plateau, USA

    Science.gov (United States)

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

    2012-12-01

    The very existence of Grand Canyon inspires questions about why canyons are carved, how drainage systems and landscapes evolve, and how these processes relate to the elevation gain of plateaus. Yet when and why Grand Canyon was carved have been extraordinarily controversial for more than 150 years. Over the last several decades, the dominant view for the origin of the canyon is one of rapid incision at 5-6 Ma, when detritus derived from the upstream reaches of the Colorado River system appeared in Grand Wash Trough at the Colorado River's western exit from the Colorado Plateau. The absence of such diagnostic deposits prior to 6 Ma has been used to argue that Grand Canyon was not yet excavated (e.g., Karlstrom et al., 2008). However, a variety of data hint at a more ancient age for part or all of the canyon, and it has been proposed that a smaller drainage basin in largely carbonate lithologies could explain the absence of pre-6 Ma Colorado River clastics in Grand Wash Trough even if a significant Grand Canyon were present. Most recently, apatite (U-Th)/He (AHe) thermochronometry data from western Grand Canyon were used to infer excavation of this area to within several hundred meters of its modern depth by ca. 70 Ma (Wernicke, 2011), an interpretation in direct conflict with the young canyon model. The unexpected implications of the initial Grand Canyon AHe work motivated the apatite 4He/3He and U-Th zonation study presented here. Apatite 4He/3He thermochronometry provides information about the spatial distribution of radiogenic 4He in an apatite crystal that can better constrain a sample's cooling history. A key premise of AHe and 4He/3He spectra interpretation is that the He kinetic model used is accurate. We first investigate whether differing 4He/3He spectra for apatites of variable AHe date, radiation damage, and U-Th zonation from eastern Grand Canyon yield mutually consistent thermal history results using the RDAAM kinetic model, which must be true if the

  9. Preparation of porous composite implant materials by in situ polymerization of porous apatite containing epsilon-caprolactone or methyl methacrylate.

    Science.gov (United States)

    Walsh, D; Furuzono, T; Tanaka, J

    2001-06-01

    Biodegradable and biostable composite foams were formed from porous apatite cement infiltrated with epsilon-caprolactone (CL) or methylmethacrylate (MMA) using a high over vacuum. For CL composites in situ polymerization was induced using trace water as an initiator and heating at 120 degrees C for up to 10 days or at 80 degrees C for 60 days. MMA composites were polymerized using AIBN initiator at 70 degrees C for 8 h. CL preparations gave composites with a polycaprolactone (PCL) number average of molecular weight (Mn) up to the maximum of 7.1 x 10(3) g/mol after 10 days and 16.8 x 10(3) g/mol after 60 days. The PCL and PMMA contents were close to 50 and 40 wt%, respectively, polymer was present as a thin coating on the apatite crystal plates and was evenly distributed throughout the samples. Re-evacuation of apatite saturated with monomer during preparation ensured that the upwards of 200 nm microchannels within the apatite cement were largely free of polymer, and the overall macroporous structure of the apatite foams was partly retained. Maximum compressive strengths increased from 9 MPa to 37 and 64 MPa for PCL and PMMA composites, respectively. The water drop contact angle of the PCL composite was 64 degrees, and therefore suitable for cell attachment. PMMA composite surfaces were more hydrophobic. Composites were subjected to corona discharge to induce suitable moderate hydrophilicity at the surface.

  10. The increase of apatite layer formation by the poly(3-hydroxybutyrate) surface modification of hydroxyapatite and β-tricalcium phosphate.

    Science.gov (United States)

    Szubert, M; Adamska, K; Szybowicz, M; Jesionowski, T; Buchwald, T; Voelkel, A

    2014-01-01

    The aim of this study was the surface modification of hydroxyapatite and β-tricalcium phosphate by poly(3-hydroxybutyrate) grafting and characterization of modificates. The bioactivity examination was carried out by the determination to grow an apatite layer on modified materials during incubation in simulated body fluid at 37°C. The additional issue taken up in this paper was to investigate the influence of fluid replacement. The process of the surface modification of biomaterials was evaluated by means of infrared and Raman spectroscopy. Formation of the apatite layer was assessed by means of scanning electron microscopy and confirmed by energy dispersive, Raman and Fourier transformed infrared spectroscopy. During exposure in simulated body fluid, the variation of the zeta potential, pH measurement and relative weight was monitored. Examination of scanning electron microscopy micrographs suggests that modification of hydroxyapatite and β-tricalcium phosphate by poly(3-hydroxybutyrate) significantly increases apatite layer formation. Raman spectroscopy evaluation revealed that the formation of the apatite layer was more significant in the case of hydroxyapatite modificate, when compared to the β-tricalcium phosphate modificate. Both modificates were characterized by stable pH, close to the natural pH of human body fluids. Furthermore, we have shown that a weekly changed, simulated body fluid solution increases apatite layer formation. © 2013.

  11. CHADS2 and CHA2DS2-VASc scores can predict thromboembolic events after supraventricular arrhythmia in the critically ill patients.

    Science.gov (United States)

    Champion, Sébastien; Lefort, Yannick; Gaüzère, Bernard-Alex; Drouet, Didier; Bouchet, Bruno Julien; Bossard, Guillaume; Djouhri, Sabina; Vandroux, David; Mayaram, Kushal; Mégarbane, Bruno

    2014-10-01

    Prediction of arterial thromboembolic events (ATEs) in relation to supraventricular arrhythmia (SVA) has been poorly investigated in the intensive care unit (ICU). We aimed at evaluating CHADS2 and CHA2DS2-VASc scores to predict SVA-related ATE in the ICU. We conducted a prospective observational study including all the patients except those in the postoperative course of cardiac surgery who presented SVA lasting 30 seconds or longer during their ICU stay. We looked for ATE during ICU stay, at the first and sixth month of follow-up after ICU discharge. During the 15-month study period, 108 (12.8%) of 846 ICU patients experienced SVA with 12 SVA-related ATE occurring 6 days (3; 13) (median, 10%-90% percentiles) after SVA onset. In our SVA patients, CHADS2 score was 2 (0; 5), and CHA2DS2-VASc score 3 (0; 7). Both CHADS2 (odds ratio (OR), 1.6 [1.1; 2.4]; P = .01) and CHA2DS2-VASc scores (OR, 1.4 [1.04; 1.8]; P = .03) were significantly associated with ATE onset. However, the most accurate threshold for predicting ATE was CHADS2 score of 4 or higher. Using a multivariate analysis, only patient's history of stroke was associated with ATE onset (OR, 9.2 [2.4; 35]; P = .001). CHADS2 and CHA2DS2-VASc scores are predictive of SVA-related thromboembolism in the critically ill patient. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Antitrombotik berdasarkan skor CHA2DS2-VASc dan skor HAS BLED terhadap pola pengobatan pada pasien stroke iskemik dengan fibrilasi atrium

    Directory of Open Access Journals (Sweden)

    Rizaldy Taslim Pinzon

    2017-06-01

    Full Text Available Stroke associated with atrial fibrillation and cardioembolism tend to manifest more severe, recurrent high risk, and higher mortality. Anticoagulation is recommended in ischemic stroke in atrial fibrillation for prevention, both primary and secondary. Stratification score CHA2DS2-VASc (Congestive Heart Failure, Hypertension, Age ≥ 75, Diabetes, Stroke, Vascular Disease, Sex-Female is used to select patients at risk of ischemic stroke for the selection of appropriate antithrombotic. The risk of bleeding is measure with HAS BLED (Hypertension, Abnormal liver/ kidney function, Stroke, Bleeding tendency, Elderly, Drug/ Alcohol score. Previous studies are very limited in research of anti thrombotic use in cardioembolic stroke. Aim this study is Measure the utilization of antittrombothic medication based on CHA2DS2-VASc score and HAS BLED in ischemic stroke patient with atrial fibrillation. This study is a cross sectional. Samples were obtained from the stroke registry and electronic medical records of patients at the Neurology Clinic of Bethesda Hospital Yogyakarta between 2009-2016. Data was analyzed using univariat approach. Data obtained from 77 patients with ischemic stroke in atrial fibrillation which consisted of 33 men (42.8% and 44 women (57.1%. The largest proportion of patients are aged> 70 years (33.3%. Results of univariate analysis showed that the use of antiplatelet there were 71 (92.2% patients, the use of anticoagulants 6 (7.7% patients, as well as a score CHA2DS2-VASc 0 = 3 (3.8%, 1 = 18 (22.5%, ≥2 = 56 (70.1%, the HAS BLED score of 0 = 7 (8.8%, 1 = 27 (33.8%, 2 = 29 (36.3%, 3 = 13 (16.3%, 4 = 1 (1.3%. CHA2DS2-VASc and HAS BLED score are not affect the use of antithrombotic agents for ischemic stroke patient with atrial fibrillation.

  13. CHADS2 and CHA2DS2-VASc score to assess risk of stroke and death in patients paced for sick sinus syndrome.

    Science.gov (United States)

    Svendsen, Jesper Hastrup; Nielsen, Jens Cosedis; Darkner, Stine; Jensen, Gunnar Vagn Hagemann; Mortensen, Leif Spange; Andersen, Henning Rud

    2013-06-01

    The risk of stroke in patients with atrial fibrillation (AF) can be assessed by use of the CHADS2 and the CHA2DS2-VASc score system. We hypothesised that these risk scores and their individual components could also be applied to patients paced for sick sinus syndrome (SSS) to evaluate risk of stroke and death. Prospective cohort study. All Danish pacemaker centres and selected centres in the UK and Canada. Risk factors were recorded prior to pacemaker implantation in 1415 patients with SSS participating in the Danish Multicenter Randomized Trial on Single Lead Atrial Pacing versus Dual Chamber Pacing in Sick Sinus Syndrome (Danpace) trial. Development of stroke was assessed at follow-up visits and by evaluation of patient charts. Mortality was assessed from the civil registration system. Patients were randomised to AAIR (N = 707) or DDDR pacing (N = 708). Stroke and death during follow-up. Mean follow-up was 4.3 ± 2.5 years. In the AAIR group 6.9% patients developed stroke versus 6.1% in the DDDR group (NS). There was a significant association between CHADS2 score and the development of stroke (HR 1.41; 95% CI 1.22 to 1.64, p < 0.001). CHA2DS2-VASc score was also significantly associated with stroke (HR 1.25; CI 1.12 to 1.40, p < 0.001). CHADS2 score (HR 1.46; CI 1.36 to 1.56, p < 0.001) and CHA2DS2-VASc score (HR 1.39; CI 1.31 to 1.46, p < 0.001) were associated with mortality. Results were still significant after adjusting for AF and anticoagulation therapy. CHADS2 and CHA2DS2-VASc score are associated with increased risk of stroke and death in patients paced for SSS irrespective of the presence of AF.

  14. Bioactive glass induced in vitro apatite formation on composite GBR membranes.

    Science.gov (United States)

    Tirri, Teemu; Rich, Jaana; Wolke, Joop; Seppälä, Jukka; Yli-Urpo, Antti; Närhi, Timo O

    2008-08-01

    The aim of this study was to investigate in vitro bioactivity of different thermoplastic biodegradable barrier membranes. Three experimental GBR membranes were fabricated using Poly(epsilon-caprolactone-co-D: ,L-lactide) P(CL/DL-LA) and particulate bioactive glass S53P4 (BAG; granule size 90-315 microm): (A) composite membrane with 60-wt.% of BAG, (B) membrane coated with BAG; and (C) copolymer membrane without BAG. Membranes were immersed in simulated body fluid (SBF), and their surfaces were characterized with SEM, XRD and EDS after 6 and 12 h and after 1, 3, 5, 7, and 14 days. Calcium phosphate (Ca-P) surface formation was observed on both composite membranes (A and B) but not on the copolymer membrane without bioactive glass (C). The Ca-P precipitation appeared to be initiated on the bioactive glass followed by growth of the layer along the polymer surface. In 6-12 h ion dissolution of the bioactive glass led to formation of the silica rich layer on the surface of the exposed glass granules on composite membrane B whereas only small amounts of silica was observed on the polymer surface of the composite membrane A. At 24 h nucleation of Ca-P precipitation was observed, and by 3-5 days membrane surface was covered with a uniform Ca-P layer transforming from amorphous to low crystalline structure. At 7 days composition and structure of the apatite surface resembled the apatite in bone. Once nucleated, the surface topography seemed to have significant effect on the growth of the apatite layer.

  15. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Apatite grown in niobium by two-step plasma electrolytic oxidation.

    Science.gov (United States)

    Pereira, Bruno Leandro; Lepienski, Carlos Maurício; Mazzaro, Irineu; Kuromoto, Neide Kazue

    2017-08-01

    Plasma electrolytic oxidation (PEO) of niobium plates were done electrochemically in two steps with electrolytes containing phosphorous and calcium being observed the formation of crystalline apatite. All samples were submitted to a first step of PEO using an electrolyte containing phosphate ions. The second oxidization step was made using three different electrolytes. Some samples were oxidized by PEO in electrolyte containing calcium, while in other samples it was used two mixtures of phosphoric acid and calcium acetate monohydrate solutions. Three different surface layers were obtained. The morphology and chemical composition of the films were analyzed by scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS) respectively. It was observed that all samples submitted to two-step oxidation shown porous surface and a calcium and phosphorus rich layer. Average surface roughness (Ra) was measured by a profilometer remaining in the sub-micrometric range. The contact angle by sessile drop technique, using 1μL of distilled water was performed with an optical goniometer. It was verified a higher hydrophilicity in all surfaces compared to the polished niobium. Orthorhombic Nb 2 O 5 was identified by XRD in the oxide layer. Crystalline apatite was identified by XRD in surfaces after the second oxidation made with the Ca-rich electrolyte and a mixture of an electrolyte richer in Ca compared to P. These results indicate that a two-step oxidized niobium surface present great features for applications in the osseointegration processes: favorable chemical composition that increase the biocompatibility, the formation of crystalline niobium pentoxide (orthorhombic), high hydrophilicity and formation of crystalline calcium phosphate (apatite) under adequate electrolyte composition. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Future Directions of Structural Mass Spectrometry using Hydroxyl Radical Footprinting

    Energy Technology Data Exchange (ETDEWEB)

    J Kiselar; M Chance

    2011-12-31

    Hydroxyl radical protein footprinting coupled to mass spectrometry has been developed over the last decade and has matured to a powerful method for analyzing protein structure and dynamics. It has been successfully applied in the analysis of protein structure, protein folding, protein dynamics, and protein-protein and protein-DNA interactions. Using synchrotron radiolysis, exposure of proteins to a 'white' X-ray beam for milliseconds provides sufficient oxidative modification to surface amino acid side chains, which can be easily detected and quantified by mass spectrometry. Thus, conformational changes in proteins or protein complexes can be examined using a time-resolved approach, which would be a valuable method for the study of macromolecular dynamics. In this review, we describe a new application of hydroxyl radical protein footprinting to probe the time evolution of the calcium-dependent conformational changes of gelsolin on the millisecond timescale. The data suggest a cooperative transition as multiple sites in different molecular subdomains have similar rates of conformational change. These findings demonstrate that time-resolved protein footprinting is suitable for studies of protein dynamics that occur over periods ranging from milliseconds to seconds. In this review, we also show how the structural resolution and sensitivity of the technology can be improved as well. The hydroxyl radical varies in its reactivity to different side chains by over two orders of magnitude, thus oxidation of amino acid side chains of lower reactivity are more rarely observed in such experiments. Here we demonstrate that the selected reaction monitoring (SRM)-based method can be utilized for quantification of oxidized species, improving the signal-to-noise ratio. This expansion of the set of oxidized residues of lower reactivity will improve the overall structural resolution of the technique. This approach is also suggested as a basis for developing hypothesis

  18. In-Situ Apatite Laser Ablation U-Th-Sm/He Dating, Methods and Challenges

    Science.gov (United States)

    Pickering, J. E.; Matthews, W.; Guest, B.; Hamilton, B.; Sykes, C.

    2015-12-01

    In-situ, laser ablation U-Th-Sm/He dating is an emerging technique in thermochronology that has been proven as a means to date zircon and monzonite1-5. In-situ U-Th-Sm/He thermochronology eliminates many of the problems and inconveniences associated with traditional, whole grain methods, including; reducing bias in grain selection based on size, shape and clarity; allowing for the use of broken grains and grains with inclusions; avoiding bad neighbour effects; and eliminating safety hazards associated with dissolution. In-situ apatite laser ablation is challenging due to low concentrations of U and Th and thus a low abundance of radiogenic He. For apatite laser ablation to be effective the ultra-high-vacuum (UHV) line must have very low and consistent background levels of He. To reduce He background, samples are mounted in a UHV stable medium. Our mounting process uses a MicroHePP (Microscope Mounted Heated Platen Press) to press samples into FEP (fluorinated ethylene propylene) bonded to an aluminum backing plate. Samples are ablated using a Resonetics 193 nm excimer laser and liberated He is measured using a quadrupole mass spectrometer on the ASI Alphachron noble gas line; collectively this system is known as the Resochron. The ablated sites are imaged using a Zygo Zescope optical profilometer and ablated pit volume measured using PitVol, a custom MatLab algorithm developed to enable precise and unbiased measurement of the ablated pit geometry. We use the well-characterized Durango apatite to demonstrate the accuracy and precision of the method. He liberated from forty-two pits, having volumes between 1700 and 9000 um3, were measured using the Resochron. The ablated sites were imaged using a Zygo Zescope optical profilometer and ablated pit volume measured using PitVol. U, Th and Sm concentrations were measured by laser ablation and the U-Th-Sm/He age calculated by standard age equation. An age of 33.8±0.31 Ma was determined and compares well with conventional

  19. Oxygen Isotope Signatures of the Apatite-Iron Oxide Ore at Grängesberg

    OpenAIRE

    Weis, Franz

    2011-01-01

    The origin of apatite iron oxide ores, like the deposit at Grängesberg in the Bergslagen mining district, has been a subject of much discussion through the years. Some support a formation by hydrothermal fluids while others suggest that the ore is orthomagmatic, i.e. formed directly from a magma as suggested for the iron ore deposits of El Laco in Chile or the deposits in Kiruna, although also these two are still subjected to controversies. In 2009 sampling was done on drillcores through the ...

  20. Secular changes in the oxygen isotopic composition of Devonian biogenic apatite

    Science.gov (United States)

    Breisig, S.; Joachimski, M. M.; Buggisch, W.

    2003-04-01

    Oxygen isotopes are a key tool for quantifying temperature and salinity of ancient sea water. Initially, pristine skeletal carbonates (preferentially LMC) have been utilized to monitor variations in the oxygen isotopic composition of past oceans. A high preservation potential of the primordial isotopic signature may also be awarded to conodonts. These microfossils consist of fluor-apatite (francolite) with a dense microcrystalline structure and therefore are comparatively insensitive with regard to diagenetic overprinting. Because conodonts are frequent in Devonian rocks and widely used as index fossils, their application for oxygen isotope analysis is espe-cially promising for this specific geological time interval. Laser-based microsampling or high-temperature combustion techniques (TC/EA) allows us to analyse microsamples of conodont apatite (0.5 to 1 mg). The oxygen isotope measurements are performed on trisilverphosphate after dissolving conodont apatite (0.5 to 1 mg) in nitric acid and precipitating the phosphate group as Ag_3PO_4. Conodont samples from different locations in Germany (Rheinisches Schieferge-birge) and the Czech Republic (Prague Basin) as well as from the United States (Iowa) and Morocco (Anti-Atlas) have been analysed. δ18Oapatite values are presented for the Lochkovian, Middle and Late Devonian. δ18Oapatite values for the Lochkovian (Prague Basin) vary between 18.5 and 19.0 ppm (δ18Oapatite values given in V-SMOW). Assuming an oxygen isotopic composition for Devonian seawater of -1 ppm (ice-free world), the δ18Oapatite values translate into tem-peratures of 26^o to 28^oC for the tropical Lochkovian ocean. Eifelian to Givetian conodonts (Rheinisches Schiefergebirge, Prague Basin) show δ18Oapatite values from 18.5 to 20.4 ppm, corresponding to paleotemperatures of 20 to 28^o C. The Middle to Late Devonian transition is mainly documented by conodonts from Iowa with δ18Oapatite values of 18 to 20 ppm (21-30^o C). Conodont δ18Oapatite

  1. 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.

  2. The Cosmological Vision of the Yoruba-Idààcha of Benin Republic (West Africa): A Light on Yoruba History and Culture

    Science.gov (United States)

    Sègla, Aimé Dafon

    The essay examines Idààcha cosmological vision as a kind of incorporation of Yoruba cosmology. It shows a process where the two strands, that is to say, knowledge and belief can not be readily distinguished. The divinatory traditional calendar is indeed based on a scale of fixed number values whose definitions are drawn from the concepts early traditional people have of the universe. Thus, the signification of the terms that designate entities such as angle, circle, center of the circle, midnight, time zone, the number of days in a week, etc., in the Yoruba dialect Idààcha, mirrors cosmological standards. These words constitute a landscape of memory shedding light on early Yoruba culture and history. Hence, Idààcha being a significant western periphery of the Yoruba region, we examine why its divinatory calendar would preserve an older spatio-temporal logic, beyond Ifè and Oyo revisionism in Yoruba history. Finally, the article points out that the translation of spatial and geometrical relations into temporal terms and vice-versa may suggest a new indexical approach to the study of cosmology in relation to the human body. As the body is in the mind, we say in relation to the human mind.

  3. Tunable photoluminescence and spectrum split from fluorinated to hydroxylated graphene

    Science.gov (United States)

    Gong, Peiwei; Wang, Jinqing; Sun, Weiming; Wu, Di; Wang, Zhaofeng; Fan, Zengjie; Wang, Honggang; Han, Xiuxun; Yang, Shengrong

    2014-02-01

    Tunable control over the functionalization of graphene is significantly important to manipulate its structure and optoelectronic properties. Yet the chemical inertness of this noble carbon material poses a particular challenge for its decoration without forcing reaction conditions. Here, a mild, operationally simple and controllable protocol is developed to synthesize hydroxylated graphene (HOG) from fluorinated graphene (FG). We successfully demonstrate that under designed alkali environment, fluorine atoms on graphene framework are programmably replaced by hydroxyl groups via a straightforward substitution reaction pathway. Element constituent analyses confirm that homogeneous C-O bonds are successfully grafted on graphene. Rather different from graphene oxide, the photoluminescence (PL) emission spectrum of the obtained HOG becomes split when excited with UV radiation. More interestingly, such transformation from FG facilitates highly tunable PL emission ranging from greenish white (0.343, 0.392) to deep blue (0.156, 0.094). Additionally, both experimental data and density function theory calculation indicate that the chemical functionalization induced structural rearrangement is more important than the chemical decoration itself in tuning the PL emission band tail and splitting energy gaps. This work not only presents a new way to effectively fabricate graphene derivatives with tunable PL performance, but also provides an enlightening insight into the PL origin of graphene related materials.Tunable control over the functionalization of graphene is significantly important to manipulate its structure and optoelectronic properties. Yet the chemical inertness of this noble carbon material poses a particular challenge for its decoration without forcing reaction conditions. Here, a mild, operationally simple and controllable protocol is developed to synthesize hydroxylated graphene (HOG) from fluorinated graphene (FG). We successfully demonstrate that under designed

  4. Sistema de asentamiento prehispánico en la sierra meridional de Chañi (Salta, Argentina

    Directory of Open Access Journals (Sweden)

    Christian Vitry

    2007-01-01

    Full Text Available El área de investigación se ubica en el sector meridional de la Sierra de Chañi, Provincia de Salta, República Argentina. La estructura espacial y distribucional de los sitios arqueológicos en el área de estudio y sistemas montañosos aledaños posee un gran potencial informativo. Estos atributos cualicuantitativos nos permiten estudiar la variabilidad y complejidad del sistema de asentamiento en la región. Nuestro abordaje parte desde las perspectivas de la evolución del paisaje cultural y el proceso de cambio geopolítico. El registro arqueológico presente en el área de estudio manifiesta una recurrencia con relación al sistema de asentamiento, para el cual proponemos un modelo hipotético de ocupación del espacio durante los períodos de Desarrollos Regionales e Inka. Durante estos períodos analizamos la interacción de las diferentes formas de poder y posibles situaciones emergentes de desigualdad social

  5. Influence of hydroxyl substitution on flavanone antioxidants properties.

    Science.gov (United States)

    Masek, Anna; Chrzescijanska, Ewa; Latos, Malgorzata; Zaborski, Marian

    2017-01-15

    The aim of our study was to determine the effect of the position of the hydroxyl group on the antioxidant properties of flavonoid derivatives. For this purpose, we performed electrochemical analysis and quantum-mechanical calculations to describe the mechanisms of electrochemical oxidation, and we selected the two methods of ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate), which allowed us to determine the ability to scavenge free radicals. On the basis of the research, we found that the derivatives of flavonoids, which have a hydroxyl group substituted at the R-3 position on the C ring, have outstanding antioxidant activity. Flavone, which had an OH group substituted at the R-6 and R-7 position on the ring A, showed similar antioxidant activity to flavone without -OH groups in the structure and slightly higher activity than the di-substituted flavone on the ring A. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Direct Hydroxylation of Benzene to Phenol over TS-1 Catalysts

    Directory of Open Access Journals (Sweden)

    Yuecheng Luo

    2018-01-01

    Full Text Available We synthesized a TS-1 catalyst to directly hydroxylate benzene to phenol with H2O2 as oxidant and water as solvent. The samples were characterized by FT-IR (Fourier Transform Infrared, DR UV-Vis (Diffused Reflectance Ultraviolet Visible, XRD (X-ray diffraction, SEM(scanning electron microscope, TEM (Transmission Electron Microscope, XPS (X-ray photoelectron spectroscopy, ICP (inductively coupled plasma spectrum, and N2 adsorption-desorption. A desirable phenol yield of 39% with 72% selectivity was obtained under optimized conditions: 0.15 g (0.34 to the mass of benzene TS-1, 5.6 mmol C6H6, reaction time 45 min, 0.80 mL H2O2 (30%, 40.0 mL H2O, and reaction temperature 70 °C. The reuse of the TS-1 catalyst illustrated that the catalyst had a slight loss of activity resulting from slight Ti leaching from the first run and then kept stable. Almost all of the Ti species added in the preparation were successfully incorporated into the TS-1 framework, which were responsible for the good catalytic activity. Extraframework Ti species were not selective for hydroxylation.

  7. Aminosilane micropatterns on hydroxyl-terminated substrates: fabrication and applications.

    Science.gov (United States)

    Li, Hai; Zhang, Juan; Zhou, Xiaozhu; Lu, Gang; Yin, Zongyou; Li, Gongping; Wu, Tom; Boey, Freddy; Venkatraman, Subbu S; Zhang, Hua

    2010-04-20

    The technique to pattern aminosilanes on hydroxyl-terminated substrates will open up extensive applications in many fields. There are some existing methods to pattern aminosilanes, in particular, (3-aminopropyl)triethoxysilane (APTES) on SiO(2) and glass substrates through indirect routes. However, few reports focus on the direct patterning of APTES by microcontact printing (microCP), due to the volatility of "inks" which consist of APTES and organic solvents. This report shows that high-quality APTES patterns on hydroxyl-terminated substrates can be directly obtained by microCP using an APTES aqueous solution as "ink". Gold nanoparticles (Au NPs) have been used to verify the presence and quality of APTES patterns on which they are selectively adsorbed. Thus-obtained Au NP patterns can serve as templates for the growth of ZnO nanostructures. Lectins are also successfully immobilized on the APTES patterns, with glutaraldehyde as linker. We believe that our method will serve as a general approach and find a wide range of applications in the fabrication of patterns and devices.

  8. Role of the hydroxyl radical in soot formation

    Science.gov (United States)

    King, Galen B.; Laurendeau, Normand M.

    1983-01-01

    The goal of this project is to determine the role of the hydroxyl radical during formation of soot. Correlations will be sought between OH concentration and (1) the critical equivalence ratio for incipient soot formation and (2) soot yield as a function of higher equivalence ratios. The ultimate aim is the development of a quasi-global kinetic model for the pre-particulate chemistry leading to soot nucleation. Hydroxyl radical concentration profiles are measured directly in both laminar premixed and diffusion flames using the newly developed technique, laser saturated fluorescence (LSF). This method is capable of measuring OH in the presence of soot particles. Aliphatic and aromatic fuels will be used to assess the influence of fuel type on soot formation. The influence of flame temperature on the critical equivalence ratio and soot yield will be related to changes in the OH concentration profiles. LSF measurements will be augmented with auxiliary measurements of soot and PAH concentrations to allow the development of a quasi-global model for soot formation.

  9. The Haber Process Made Efficient by Hydroxylated Graphene

    CERN Document Server

    Chaban, Vitaly

    2016-01-01

    The Haber-Bosch process is the main industrial method for producing ammonia from diatomic nitrogen and hydrogen. Very demanding energetically, it uses an iron catalyst, and requires high temperature and pressure. Any improvement of the Haber process will have an extreme scientific and economic impact. We report a significant increase of ammonia production using hydroxylated graphene. Exploiting the polarity difference between N2/H2 and NH3, as well as the universal proton acceptor behavior of NH3, we demonstrate a strong shift of the equilibrium of the Haber-Bosch process towards ammonia. Hydroxylated graphene provides the polar environment favoring the forward reaction, and remain stable under the investigated thermodynamic conditions. Ca. 50 kJ mol-1 enthalpy gain and ca. 60-70 kJ mol-1 free energy gain are achieved at 298-1300 K and 1-1000 bar, strongly shifting the reaction equilibrium towards the product. A clear microscopic interpretation of the observed phenomenon is given using electronic structure ca...

  10. Relationship of CHA2DS2-VASc and CHADS2 score to left atrial remodeling detected by velocity vector imaging in patients with atrial fibrillation.

    Directory of Open Access Journals (Sweden)

    Yihui Li

    Full Text Available BACKGROUND: The CHADS2/CHA2DS2-VASc scores are used to predict thrombo-embolic/stroke in patients with nonvalvular atrial fibrillation (AF. Nevertheless, limited data are available regarding the association between these risk stratification for stroke and left atrial (LA remodeling status of AF patients. The purpose of this study was to explore the association between these scores and LA remodeling status assessed quantificationally by echocardiography in AF patients. METHODS: One hundred AF patients were divided into 3 groups based on the CHA2DS2-VASc/CHADS2 score: the score of 0 (low stroke risk, the score of 1 (moderate stroke risk and the score of ≥2 (high stroke risk. All patients were performed through conventional and velocity vector imaging echocardiography. Echocardiographic parameters: maximum LA volume index (LAVImax, LA total emptying fraction (LAEFt and LA mean strain were obtained to assess quantificationally LA remodeling status. RESULTS: On categorizing with CHA2DS2-VASc, the score of 1 group showed augment in LAVImax and attenuation in LA mean strain derived from VVI, compared with the score of 0 group (LAVImax: 40.27±21.91 vs. 26.79±7.87, p=0.002; LA mean strain: 15.18±6.36 vs. 22±8.54, p=0.001. On categorizing with the CHADS2 score, similar trends were seen between the score of ≥2 and 1 groups (LAVImax: 43.72±13.77 vs. 31.41±9.50, p<0.001; LA mean strain: 11.01±5.31 vs. 18.63±7.00, p<0.001. With multivariate logistic regression, LAVImax (odds ratio: 0.92 , 95% C=I: 0.85 to 0.98, p= 0.01 and LA mean strain reflecting LA remodeling (odds ratio: 1.10, 95% CI: 1.02 to 1.19, p=0.01 were strongly predictive of the CHA2DS2-VASc score of 0. CONCLUSIONS: The superiority of the CHADS2 score may lay in identifying LA remodeling of AF patients with high stroke risk. Whereas, the CHA2DS2-VASc score was better than the CHADS2 score at identifying LA remodeling of AF patients presenting low stroke risk.

  11. Validity of the Apatite/Merrillite Relationship in Evaluating the Water Content in the Martian Mantle: Implications from Shergottite Northwest Africa (NWA 2975

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    Ewa Słaby

    2017-10-01

    Full Text Available Phosphates from the Martian shergottite NWA 2975 were used to obtain insights into the source and subsequence differentiation of the melt/melts. The crystallization of two generations of fluorapatite (F > Cl~OH and F-rich, chlorapatite and ferromerrillite-merrillite were reconstructed from TEM (Transmission Electron Microscopy and geochemical analyses. The research results indicated that the recognized volatiles budget of the two generations of fluorapatite was related to their magmatic origin. The apatite crystals crystallized from an evolved magma during its final differentiation and degassing stage. In turn, chlorapatite replaced ferromerrillite-merrillite and was not related to, mantle-derived shergottite magma. The relationship between merrillite and apatite indicates that apatite is most probably a product of merrillite reacting with fluids. REE (rare earth elements pattern of Cl-apatite might point to an origin associated with exogenous fluids mixed with fluids exsolved from evolved magma. The study shows that, among the three types of apatite, only the fluorapatite (F > Cl~OH is a reliable source for assessing the degree of Martian mantle hydration. The occurrence of apatite with merrillite requires detailed recognition of their relationship. Consequently, the automatic use of apatite to assess the water content of the magma source can lead to false assumptions if the origin of the apatite is not precisely determined.

  12. Investigation of vacancy damage influence on He diffusion in apatite: implication for the (U-Th)/He thermochronometer

    Science.gov (United States)

    Gautheron, Cécile; Gerin, Chloé; Bachelet, Cyril; Mbongo Djimbi, Duval; Seydoux-Guillaume, Anne-Magali; Tassan-Got, Laurent; Roques, Jérôme; Garrido, Frédérico

    2017-04-01

    Helium diffusion in minerals rich in actinides, especially apatite, is considered as strongly impacted by damage, even at low U-Th content. However, no direct evidence exists neither about such an impact nor the damage topology. To better understand the impact of damage on He diffusion, we conducted a study on vacancy damage in apatite, at nanometric to atomic scales, using several methodologies [1]. We investigate the role of vacancy damage that are the one created during alpha decay. Firstly, Transmission Electron Microscopy (TEM) was used to image the damage structure done by He implantation in the first 200 nm below the surface of apatite crystal. TEM images present no visible damage zone at nano-scale, implying that the created damage corresponds well to Frenkel defects (vacancies and interstitials). Secondly, to test the damage impact on diffusion and the trapping efficiency, we conduct both experimental and theoretical studies. Diffusion experiments were performed on He implanted samples by mapping He concentration vs. depth profiles using Elastic Recoil Detection Analysis (ERDA). After measurement of implanted-He profiles and He concentrations, the samples were heated in order to diffuse the implanted profile. The obtained He vs. depth heated profiles and He concentrations reveal the impact of damage on He diffusivity. The results can only be explained by a model where diffusion depends on damage dose, taking into account He trapping in vacancies and damage interconnectivity at higher damage dose. Thirdly, Density Functional Theory (DFT) calculations were performed to simulate a vacancy in a F-apatite crystal, and results are compared with an undamaged apatite cell [2]. The structure becomes slightly deformed by the vacancy and the insertion energy of a He atom in the vacancy is lower than for an usual insertion site. Accordingly, the additional energy for a He atom to jump out of the vacancy is in good agreement with published estimates. This calculation

  13. 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.; hide

    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

  14. Protein release parameters estimated with a flow system on zinc-containing apatite

    Energy Technology Data Exchange (ETDEWEB)

    Inaba, M; Kanno, T; Tada, K; Horiuchi, J [Department Biotechnology and Environmental Chemistry, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507, Hokkaido Pref. (Japan); Akazawa, T; Itabashi, K, E-mail: kannotr@mail.kitami-it.ac.jp [Hokkaido Industrial Research Institute, Nishi-11 Kita-19, Kita-ku, Sapporo 060-0819, Hokkaido Pref. (Japan)

    2011-10-29

    Adsorption and desorption properties of proteins on zinc-containing apatite were successively monitored with a newly-developed flow system, and sustained-release ability of the apatite with different zinc contents was evaluated using protein release parameters we suggested. Three sustained-release parameters; initial desorption rate (r{sub init}), time of desorption-completed (T{sub des}), and desorption constant (k{sub d}) were estimated with graphical analysis of dynamic desorption curves in a flow of 20 mM phosphate-buffered solution (PBS). Bovine serum albumin (BSA) of isoelectric point (pI) 4.8 and egg white lysozyme (LSZ) of pI 11.2 were employed as model protein drugs. Incorporation of zinc into hydroxyapatite changed desorption responses of the proteins. Zn(0.15), where the number in parentheses denoted the preparing molar ratio of Zn/Ca, showed the most sustained-release ability: less r{sub init}, longer T{sub des}, and smaller k{sub d}. Furthermore, the adsorbed amounts of the proteins for Zn(0.15) were 1.5 {approx} 4 times larger than Zn(0), which suggested that Zn(0.15) would be promising as a sustained-release carrier of protein drugs.

  15. Influence of titania nanotube arrays on biomimetic deposition apatite on titanium by alkali treatment

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Xiufeng; Tian Tian [College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007 (China); Liu Rongfang [College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007 (China)], E-mail: rfliu@vip.sina.com; She Houde [College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007 (China)

    2007-11-15

    Titania nanotube arrays were fabricated by anodic oxidation of titanium foils in HF solution, which were then treated in NaOH solution or Ca(OH){sub 2} solution to make them bioactive. The ability to form apatite on the as-treated samples was examined by immersion tests in simulated body fluid combined with Enviromental Scanning Electron Microscopy (ESEM), Energy Dispersive X-ray Analyzer (EDAX) and X-ray diffractometer (XRD) investigations. The results show that the presence of titania nanotube arrays on titanium surface could shorten the activation time of NaOH-treated from 24 h to 30 min, and induces the growth of nano-grain calcium titanate on the top edge of the nanotube wall in Ca(OH){sub 2} solution. During the subsequent in vitro immersion in a simulated body fluid, the nano-grain calcium titanate, in turn, induced the formation of apatite phase. It is expected that titanium with such titania nanotube can be used in clinical orthopaedics.

  16. 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.

  17. Development of layered anode structures supported over Apatite-type Solid Electrolytes

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    Pandis P.

    2016-01-01

    Full Text Available Apatite-type lanthanum silicates (ATLS materials have attracted interest in recent literature as solid electrolytes for SOFCs. The fabrication of an ATLS based fuel cell with the state-of-art electrodes (NiO/YSZ as anode and LSCF or LSM as cathode can show degradation after long operation hours due to Si diffusion mainly towards the anode. In this work, we report a “layer-by-layer anodic electrodes” fabrication by means of spin coating and physical spraying. The overall aim of this work is the successful fabrication of such a layered structure including suitable blocking layers towards the inhibition of Si interdiffusion from the apatite electrolyte to the anode. The results showed that the deposition of 3 layers of LFSO/GDC (3μm, NiO/GDC (4μm and the final NiO/YSZ anode layer provided a stable half-cell, with no solid state reaction occurring among the electrodes and no Si diffusion observed towards the anode after thermal treatment at 800°C for 120h.

  18. Design and properties of novel gallium-doped injectable apatitic cements.

    Science.gov (United States)

    Mellier, Charlotte; Fayon, Franck; Boukhechba, Florian; Verron, Elise; LeFerrec, Myriam; Montavon, Gilles; Lesoeur, Julie; Schnitzler, Verena; Massiot, Dominique; Janvier, Pascal; Gauthier, Olivier; Bouler, Jean-Michel; Bujoli, Bruno

    2015-09-01

    Different possible options were investigated to combine an apatitic calcium phosphate cement with gallium ions, known as bone resorption inhibitors. Gallium can be either chemisorbed onto calcium-deficient apatite or inserted in the structure of β-tricalcium phosphate, and addition of these gallium-doped components into the cement formulation did not significantly affect the main properties of the biomaterial, in terms of injectability and setting time. Under in vitro conditions, the amount of gallium released from the resulting cement pellets was found to be low, but increased in the presence of osteoclastic cells. When implanted in rabbit bone critical defects, a remodeling process of the gallium-doped implant started and an excellent bone interface was observed. The integration of drugs and materials is a growing force in the medical industry. The incorporation of pharmaceutical products not only promises to expand the therapeutic scope of biomaterials technology but to design a new generation of true combination products whose therapeutic value stem equally from both the structural attributes of the material and the intrinsic therapy of the drug. In this context, for the first time an injectable calcium phosphate cement containing gallium was designed with properties suitable for practical application as a local delivery system, implantable by minimally invasive surgery. This important and original paper reports the design and in-depth chemical and physical characterization of this groundbreaking technology. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. 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

    2016-04-06

    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.

  20. In-situ Strontium Isotopes Analysis on Single Conodont Apatite by LA-MC-ICP-MS

    Science.gov (United States)

    Zhao, L.; Zhang, L.; Chen, Z. Q.; Ma, D.; Qiu, H.; Lv, Z.; Hu, Z.; Wang, F.

    2014-12-01

    Strontium isotope played an important role in stratigraphic chronology and sedimentary geochemistry research (McArthur et al., 2001). Conodonts is a kind of extinct species of marine animals and widely distributed in marine sediments all over the world. Rich in radiogenic Sr contents and difficulty to be affected during diagenesis alteration makes conodonts a good choice in seawater Sr isotope composition studies (John et al., 2008). Conodont samples were collected from 24th to 39th layer across Permian-Triassic boundary at Meishan D section (GSSP), Zhejiang Province, South China (Yin et al., 2001). Conodonts was originated from fresh limestone and only conodont elements with CAIextinction events during the Permian-Triassic transition. Our study also makes is possible for high resolution 87Sr/ 86Sr ratio testing on the single conodont apatite and riched the in-situ studies on the conodont apatite, which of great significance for the future conodont Sr isotope research (Zhao et al., 2009; Zhao et al., 2013). Keywords: Conodonts, Strontium isotope, LA-MC-ICP-MS, Permian-Triassic transition, Meishan D section [1] John et al., 2008 3P[2] McArthur et al., 2001 J. of Geology [3] Yin et al., 2001 Episodes [4] Zhao et al., 2009 Earth Science J. of CUG [5] Zhao et al., 2013 GPC.

  1. Mechanism and Kinetics for the Dissolution of Apatitic Materials in Acid Solutions

    Directory of Open Access Journals (Sweden)

    Calmanovici C.E.

    1997-01-01

    Full Text Available Abstract - This work concerns the study of the digestion step in the production process of phosphoric acid. Some qualitative experiments indicate that the difference between the pH at the surface of the phosphate and that in the bulk of the solution is negligible and that the dissolution is controlled by diffusion of products away from the phosphate particle. In further experiments, to isolate the dissolution phenomenon from the formation of calcium sulfate, the sulfuric acid normally used industrially is replaced by hydrochloric acid. The phosphate material used in our experiments is a model apatitic material: synthetic hydroxyapatite (HAP. The dissolution of calcium hydroxyapatite was studied with increasing amounts of calcium and phosphate at different temperatures. A simple method was developed for this observation based on the time required for complete dissolution of the HAP powder. The results confirm that the dissolution is controlled by a diffusional process through an interface of calcium and phosphate ions released from the solid surface. A kinetic model for the dissolution of apatitic materials is proposed which assumes a shrinking particle behaviour controlled by diffusion of calcium ions. The experimental results are fitted to this model to determine the mass transfer constant for HAP dissolution in acid solutions. The activation energy of the reaction is about 14kJ/mol. This study was carried on in conditions similar to the industrial ones for the production of phosphoric acid by the dihydrate-process

  2. Effect of the chemical impurities on the luminescence emission of natural apatites.

    Science.gov (United States)

    Roman-Lopez, J; Correcher, V; Garcia-Guinea, J; Prado-Herrero, P; Rivera, T; Lozano, I B

    2014-05-21

    This paper reports on both cathodoluminescence (CL) and blue thermoluminescence (TL) emission of well-characterized natural Spanish and Brazilian apatites [Ca5(PO4)3(OH, F, Cl)]. Chemical analyses performed by means of Electron Microprobe Analysis (EMPA) have shown the presence of trace elements that can induce CL bands. In this sense, the apatites shown emission bands peaked at 3.26, 2.86, 2.62, 2.14, 2.02 and 1.94eV are respectively linked to substitutional Ce(3+), Tb(3+), Dy(3+), Pr(3+), Sm(3+) and Mn(2+) in structural Ca(2+) positions. The 3.18eV emission band can be associated with intrinsic electron defects on oxygen of the phosphate group (PO4)(3-). The presence of (UO2)(2+) gives rise to an emission at 2.14eV. All the studied aliquots exhibit one single UV-blue TL peak that modifies the position from one sample to another (370, 256 and 268°C) probably due to (i) the variation in the crystallinity index (from 0.88 to 1.34) and (ii) successive chemical processes such as oxidation, dehydration, dehydroxylation, and fluorine ions losses due to the thermal readout. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Molecular dynamics study of the thermodynamic properties of calcium apatites. 2. Monoclinic phases.

    Science.gov (United States)

    Cruz, Fernando J A L; Canongia Lopes, José N; Calado, Jorge C G

    2006-03-09

    Structural and thermodynamic properties of crystalline monoclinic calcium apatites, Ca10(PO4)6(X)2 (X=OH, Cl), were investigated for the first time using a molecular dynamics (MD) technique under a wide range of temperature and pressure conditions. The accuracy of the model at room temperature and atmospheric pressure was checked against crystal structural data, yielding maximum deviations of ca. 2%. The standard molar lattice enthalpy (DeltalatHo298) of the apatites was also calculated and compared with previously published experimental and MD results for the hexagonal polymorphs. High-temperature simulation runs were used to estimate the isobaric thermal expansivity coefficient and study the behavior of the crystal structure under heating. The heat capacity at constant pressure, Cp, in the range 298-1298 K, was estimated from the plot of the molar enthalpy of the crystal as a function of temperature, Hm=(Hm,298-298Cp,m)+Cp,mT, yielding Cp,m=635+/-7 J.mol-1.K-1 and Cp,m=608+/-14 J.mol-1.K-1 for hydroxy- and chlorapatite, respectively. High-pressure MD experiments, in the 0.5-75 kbar range, were performed to estimate the isothermal compressibility. The Parsafar-Mason equation of state was successfully used to fit the high-pressure p-Vm data, with an accuracy better than 0.03%.

  4. The Lac Des Iles Palladium Deposit, Ontario, Canada. Part II. Halogen variations in apatite

    Science.gov (United States)

    Schisa, Paul; Boudreau, Alan; Djon, Lionnel; Tchalikian, Arnaud; Corkery, John

    2015-03-01

    Analysis of apatite from the Mine Block Intrusion (MBI) of the Lac des Iles Igneous Complex shows two pronounced trends in the halogens. Apatite from relatively fresh norite and melanorites from the Pd-sulfide zone contain up to 57 mol% chlorapatite endmember with significant hydroxyapatite component. In contrast, in altered rock (amphibolite and greenschist assemblages) the chlorapatite component is typically less than 10 mol% with wide variation in the F- and OH-endmember components. The latter trend is attributed to Cl loss to degassing and alteration, whereas the former is attributed to Cl enrichment in the ore-bearing rocks. It is suggested that the relatively H2O-rich and intermediate Cl content of the early igneous fluids degassed from the deeper levels of the MBI can explain the high Pd/Pt and Pd/Ir ratios of the deposit. A model is presented in which disseminated Pd-rich sulfides are initially introduced by a high-temperature magmatic fluid that also influenced crystallization to produce the gross modal variations of the igneous host rock. This high-temperature mineralization event was subsequently modified by the influx of late igneous and country fluids at amphibolite to greenschist conditions.

  5. Halogen Variations in Apatite of the Lac Des Iles Palladium Deposit, Ontario, Canada

    Science.gov (United States)

    Boudreau, A. E.

    2014-12-01

    Analysis of apatite from the Mine Block Intrusion (MBI) of the Lac des Iles Igneous Complex show two pronounced trends in the halogens. Apatite from relatively fresh norite and melanorites from the Pd-sulfide zone contain up to 57 mole % chlorapatite endmember with significant hydroxyapatite component. In contrast, in altered rock (amphibolite and greenschist assemblages) and in the more evolved barren rocks the chlorapatite component is typically less than 10 mole % with wide variation in the F- and OH-endmember components. The latter trend is attributed to Cl loss to degassing and alteration whereas the former is attributed to Cl-enrichment in the ore-bearing rocks. It is suggested that the relatively H2O-rich and intermediate Cl content of the early igneous fluids degassed from the deeper levels of the MBI can explain the high Pd/Pt and Pd/Ir ratios of the deposit. A model is presented in which disseminated Pd-rich sulfide are initially introduced by a high temperature magmatic fluid that also influenced crystallization to produce the gross modal variations of the igneous host rock. This high temperature mineralization event was subsequently modified by the influx of late igneous and country fluids at amphibolite to greenschist conditions.

  6. 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.

  7. Multi-scale simulations of apatite-collagen composites: from molecules to materials

    Science.gov (United States)

    Zahn, Dirk

    2017-03-01

    We review scale-bridging simulation studies for the exploration of atomicto-meso scale processes that account for the unique structure and mechanic properties of apatite-protein composites. As the atomic structure and composition of such complex biocomposites only partially is known, the first part (i) of our modelling studies is dedicated to realistic crystal nucleation scenarios of inorganic-organic composites. Starting from the association of single ions, recent insights range from the mechanisms of motif formation, ripening reactions and the self-organization of nanocrystals, including their interplay with growth-controlling molecular moieties. On this basis, (ii) reliable building rules for unprejudiced scale-up models can be derived to model bulk materials. This is exemplified for (enamel-like) apatite-protein composites, encompassing up to 106 atom models to provide a realistic account of the 10 nm length scale, whilst model coarsening is used to reach μm length scales. On this basis, a series of deformation and fracture simulation studies were performed and helped to rationalize biocomposite hardness, plasticity, toughness, self-healing and fracture mechanisms. Complementing experimental work, these modelling studies provide particularly detailed insights into the relation of hierarchical composite structure and favorable mechanical properties.

  8. Consequences of IkappaB alpha hydroxylation by the factor inhibiting HIF (FIH).

    Science.gov (United States)

    Devries, Ingrid L; Hampton-Smith, Rachel J; Mulvihill, Melinda M; Alverdi, Vera; Peet, Daniel J; Komives, Elizabeth A

    2010-12-01

    The factor inhibiting HIF-1 (FIH-1) hydroxylates many ankyrin repeat-containing proteins including IκBα. It is widely speculated that hydroxylation of IκBα has functional consequences, but the effects of hydroxylation have not been demonstrated. We prepared hydroxylated IκBα and compared it to the unhydroxylated protein. Urea denaturation and amide H/D exchange experiments showed no change in the "foldedness" upon hydroxylation. Surface plasmon resonance measurements of binding to NFκB showed no difference in the NFκB binding kinetics or thermodynamics. Ubiquitin-independent proteasomal degradation experiments showed no difference in the half-life of the protein. Thus, it appears that hydroxylation of IκBα by FIH-1 is inconsequential, at least for the functions we could assay in vitro. Copyright © 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  9. Temperature and hydroxyl concentration dependences of diffusion coefficients of hydroxyl groups in vitreous silica at temperatures of 850–1200 °C

    Science.gov (United States)

    Kuzuu, Nobu; Sato, Naoya; Arakawa, Yu; Horikoshi, Hideharu; Horii, Naohiro

    2017-11-01

    The hydroxyl concentration and temperature dependences of the diffusion coefficients of hydroxyl groups in vitreous silica were investigated by analyzing the change in the hydroxyl concentration distribution caused by heat treatment around the binding interface between silica glass plates with different hydroxyl concentrations. We confirmed experimentally that the diffusion coefficient is proportional to the hydroxyl concentration, which had been predicted theoretically, and obtained the empirical formula D(c OH) = [(4.9 ± 1.0) × 10‑14 m2/s·wt ppm] × exp[‑(8.1 ± 0.3) × 103 K/T] c OH with the hydroxyl concentration c OH and the absolute temperature T, which is valid at least in the temperature range of 850–1200 °C. Using the values calculated using this formula, we can reproduce the hydroxyl concentration profile after diffusion from a silica glass surface induced by heating in a water vapor atmosphere in the literature, which supports the validity of the empirical formula obtained in this study. The relationship between the effective diffusion coefficient in the literature and our result is discussed.

  10. Aliphatic peptidyl hydroperoxides as a source of secondary oxidation in hydroxyl radical protein footprinting

    OpenAIRE

    Saladino, Jessica; Liu, Mian; Live, David; Sharp, Joshua S.

    2009-01-01

    Hydroxyl radical footprinting is a technique for studying protein structure and binding that entails oxidizing a protein system of interest with diffusing hydroxyl radicals, and then measuring the amount of oxidation of each amino acid. One important issue in hydroxyl radical footprinting is limiting amino acid oxidation by secondary oxidants to prevent uncontrolled oxidation which can cause amino acids to appear more solvent accessible than they really are. Previous work suggested that hydro...

  11. New hydroxylated metabolites of 4-monochlorobiphenyl in whole poplar plants

    Directory of Open Access Journals (Sweden)

    Zhai Guangshu

    2011-12-01

    Full Text Available Abstract Two new monohydroxy metabolites of 4-monochlorobiphenyl (CB3 were positively identified using three newly synthesized monohydroxy compounds of CB3: 2-hydroxy-4-chlorobiphenyl (2OH-CB3, 3-hydroxy-4-chlorobiphenyl (3OH-CB3 and 4-hydroxy-3-chlorobiphenyl (4OH-CB2. New metabolites of CB3, including 2OH-CB3 and 3OH-CB3, were confirmed in whole poplars (Populus deltoides × nigra, DN34, a model plant in the application of phytoremediation. Furthermore, the concentrations and masses of 2OH-CB3 and 3OH-CB3 formed in various tissues of whole poplar plants and controls were measured. Results showed that 2OH-CB3 was the major product in these two OH-CB3s with chlorine and hydroxyl moieties in the same phenyl ring of CB3. Masses of 2OH-CB3 and 3OH-CB3 in tissues of whole poplar plants were much higher than those in the hydroponic solution, strongly indicating that the poplar plant itself metabolizes CB3 to both 2OH-CB3 and 3OH-CB3. The total yield of 2OH-CB3 and 3OH-CB3, with chlorine and hydroxyl in the same phenyl ring of CB3, was less than that of three previously found OH-CB3s with chlorine and hydroxyl in the opposite phenyl rings of CB3 (2'OH-CB3, 3'OH-CB3, and 4'OH-CB3. Finally, these two newly detected OH-CB3s from CB3 in this work also suggests that the metabolic pathway was via epoxide intermediates. These five OH-CB3s clearly showed the complete metabolism profile from CB3 to monohydroxylated CB3. More importantly, it's the first report and confirmation of 2OH-CB3 and 3OH-CB3 (new metabolites of CB3 in a living organism.

  12. Self-hydroxylation of the splicing factor lysyl hydroxylase, JMJD6

    DEFF Research Database (Denmark)

    Mantri, M.; Webby, C.J.; Loik, N.D.

    2012-01-01

    The lysyl 5S-hydroxylase, JMJD6 acts on proteins involved in RNA splicing. We find that in the absence of substrate JMJD6 catalyses turnover of 2OG to succinate. H-NMR analyses demonstrate that consumption of 2OG is coupled to succinate formation. MS analyses reveal that JMJD6 undergoes self......-hydroxylation in the presence of Fe(ii) and 2OG resulting in production of 5S-hydroxylysine residues. JMJD6 in human cells is also found to be hydroxylated. Self-hydroxylation of JMJD6 may play a regulatory role in modulating the hydroxylation status of proteins involved in RNA splicing. This journal is...

  13. Spectroscopic study of combustion diagnostics on hydroxyl radicals

    Science.gov (United States)

    Hung, R. J.

    1990-01-01

    Experimental observations of propane-air flames were performed. Measurements of hydroxyl (OH) radical concentration were made using resonance line absorption techniques. A microwave-pumped low pressure discharge in argon and water vapor is employed to produce strong OH radical band radiation in the 308 nm region. This radiation is transmitted through the plume and absorption data are taken at various radical positions using an optical multichannel analyzer. This absorption data is used to compute OH number density using a model for the absorption band characteristics as a function of temperature based on an atlas of line strengths. A numerical computation of flow fields, temperature profile and OH number density is carried out by using a technique of computational fluid dynamics (CFD). The results of CFD computation are good compared with experimental observation with a good agreement.

  14. Spectroscopy and reaction dynamics of collision complexes containing hydroxyl radicals

    Energy Technology Data Exchange (ETDEWEB)

    Lester, M.I. [Univ. of Pennsylvania, Philadelphia (United States)

    1993-12-01

    The DOE supported work in this laboratory has focused on the spectroscopic characterization of the interaction potential between an argon atom and a hydroxyl radical in the ground X{sup 2}II and excited A {sup 2}{summation}{sup +} electronic states. The OH-Ar system has proven to be a test case for examining the interaction potential in an open-shell system since it is amenable to experimental investigation and theoretically tractable from first principles. Experimental identification of the bound states supported by the Ar + OH (X {sup 2}II) and Ar + OH(A {sup 2}{summation}{sup +}) potentials makes it feasible to derive realistic potential energy surfaces for these systems. The experimentally derived intermolecular potentials provide a rigorous test of ab initio theory and a basis for understanding the dramatically different collision dynamics taking place on the ground and excited electronic state surfaces.

  15. Further Highly Hydroxylated Steroids from the Vietnamese Starfish Archaster typicus.

    Science.gov (United States)

    Hanh, Tran Thi Hong; Vien, Le Thi; Vinh, Le Ba; Thanh, Nguyen Van; Cuong, Nguyen Xuan; Nam, Nguyen Hoai; Thung, Do Cong; Kiem, Phan Van; Minh, Chau Van

    2016-01-01

    Eight highly hydroxylated steroids (1-8), including three new compounds as sodium salts of (24S)-5α-cholestane-3β,4β,5,6α,7β,8,14,15α,24-nonaol 6-sulfate (1), (24E)-5α-cholest-24-ene-26-yde-3β,6α,8,14,15α-pentaol 15-sulfate (2), and 5α-cholest-3β,6α,8,14,15α,24,25,26-octaol 15-sulfate (3), were isolated and elucidated from the methanol extract of the Vietnamese starfish Archaster typicus. The structure elucidation was done by spectroscopic methods including one and two dimensional (1D-, 2D-)NMR and Fourier transform ion cyclotron resonance (FT-ICR)-MS. The isolated compounds can be used as chemical markers for taxonomic identification of the starfish A. typicus.

  16. Effective L-Tyrosine Hydroxylation by Native and Immobilized Tyrosinase.

    Science.gov (United States)

    Cieńska, Małgorzata; Labus, Karolina; Lewańczuk, Marcin; Koźlecki, Tomasz; Liesiene, Jolanta; Bryjak, Jolanta

    2016-01-01

    Hydroxylation of L-tyrosine to 3,4-dihydroxyphenylalanine (L-DOPA) by immobilized tyrosinase in the presence of ascorbic acid (AH2), which reduces DOPA-quinone to L-DOPA, is characterized by low reaction yields that are mainly caused by the suicide inactivation of tyrosinase by L-DOPA and AH2. The main aim of this work was to compare processes with native and immobilized tyrosinase to identify the conditions that limit suicide inactivation and produce substrate conversions to L-DOPA of above 50% using HPLC analysis. It was shown that immobilized tyrosinase does not suffer from partitioning and diffusion effects, allowing a direct comparison of the reactions performed with both forms of the enzyme. In typical processes, additional aeration was applied and boron ions to produce the L-DOPA and AH2 complex and hydroxylamine to close the cycle of enzyme active center transformations. It was shown that the commonly used pH 9 buffer increased enzyme stability, with concomitant reduced reactivity of 76%, and that under these conditions, the maximal substrate conversion was approximately 25 (native) to 30% (immobilized enzyme). To increase reaction yield, the pH of the reaction mixture was reduced to 8 and 7, producing L-DOPA yields of approximately 95% (native enzyme) and 70% (immobilized). A three-fold increase in the bound enzyme load achieved 95% conversion in two successive runs, but in the third one, tyrosinase lost its activity due to strong suicide inactivation caused by L-DOPA processing. In this case, the cost of the immobilized enzyme preparation is not overcome by its reuse over time, and native tyrosinase may be more economically feasible for a single use in L-DOPA production. The practical importance of the obtained results is that highly efficient hydroxylation of monophenols by tyrosinase can be obtained by selecting the proper reaction pH and is a compromise between complexation and enzyme reactivity.

  17. Effective L-Tyrosine Hydroxylation by Native and Immobilized Tyrosinase.

    Directory of Open Access Journals (Sweden)

    Małgorzata Cieńska

    Full Text Available Hydroxylation of L-tyrosine to 3,4-dihydroxyphenylalanine (L-DOPA by immobilized tyrosinase in the presence of ascorbic acid (AH2, which reduces DOPA-quinone to L-DOPA, is characterized by low reaction yields that are mainly caused by the suicide inactivation of tyrosinase by L-DOPA and AH2. The main aim of this work was to compare processes with native and immobilized tyrosinase to identify the conditions that limit suicide inactivation and produce substrate conversions to L-DOPA of above 50% using HPLC analysis. It was shown that immobilized tyrosinase does not suffer from partitioning and diffusion effects, allowing a direct comparison of the reactions performed with both forms of the enzyme. In typical processes, additional aeration was applied and boron ions to produce the L-DOPA and AH2 complex and hydroxylamine to close the cycle of enzyme active center transformations. It was shown that the commonly used pH 9 buffer increased enzyme stability, with concomitant reduced reactivity of 76%, and that under these conditions, the maximal substrate conversion was approximately 25 (native to 30% (immobilized enzyme. To increase reaction yield, the pH of the reaction mixture was reduced to 8 and 7, producing L-DOPA yields of approximately 95% (native enzyme and 70% (immobilized. A three-fold increase in the bound enzyme load achieved 95% conversion in two successive runs, but in the third one, tyrosinase lost its activity due to strong suicide inactivation caused by L-DOPA processing. In this case, the cost of the immobilized enzyme preparation is not overcome by its reuse over time, and native tyrosinase may be more economically feasible for a single use in L-DOPA production. The practical importance of the obtained results is that highly efficient hydroxylation of monophenols by tyrosinase can be obtained by selecting the proper reaction pH and is a compromise between complexation and enzyme reactivity.

  18. Hydroxyl radical yields from reactions of terpene mixtures with ozone.

    Science.gov (United States)

    Forester, C D; Wells, J R

    2011-10-01

    Chamber studies were conducted to quantify hydroxyl radical (OH·) yields and to determine whether water vapor affected OH· formation in the reactions of ozone (O(3)) with a single terpene, two-component terpene mixtures, and a commercial pine oil cleaning product (POC). Solid-phase microextraction fibers (SPME) were used for sampling the terpenes and the 2-butanone formation from the hydroxyl reaction with 2-butanol as a measure of OH· yields. Analyses were performed using gas chromatography with flame ionization detection. The individual terpenes' OH· yields from α-terpineol, limonene, and α-pinene were 64 ± 8%, 64 ± 6%, and 76 ± 6%, respectively. OH· yields were also measured from two-component mixtures of these terpenes. In each mixture that contained α-terpineol, the overall OH· yield was lower than the modeled OH· yields of the individual components that comprised the reaction mixture. Reactions of a commercial POC with O(3) were also studied to determine how the individual terpenes react in a complex mixture system, and an OH· formation yield of 51 ± 6% was measured. Relative humidity did not have a significant effect on the OH· formation in the mixtures studied here. The data presented here demonstrate that mixtures may react differently than the sum of their individual components. By investigating the chemistry of mixtures of chemicals in contrast to the chemistry of individual compounds, a better assessment can be made of the overall impact cleaning products have on indoor environments. © 2011 John Wiley & Sons A/S.

  19. Strontium-containing apatite/polylactide composites enhance bone formation in osteopenic rabbits.

    Science.gov (United States)

    Luo, Xiaoman; Barbieri, Davide; Duan, Rongquan; Yuan, Huipin; Bruijn, Joost D

    2015-10-01

    Strontium (Sr) has been shown to favor bone formation and is used clinically to treat osteoporosis. We have previously reported that Sr addition in apatite/polylactide composites could enhance the BMP-induced bone formation around implants at ectopic site in healthy animals. In this study we aimed to investigate the effectiveness of Sr addition on the local bone formation in osteoporosis. Apatite/polylactide composite granules with different Sr content were loaded with equal amount of rhBMP-2 and implanted intramuscularly in healthy rabbits (Con) and rabbits that received bilateral ovariectomy and daily injection of glucocorticoid (OP) for 12 weeks. The potential effect of Sr on the final volume of BMP-induced bone in both groups was investigated histologically and histomorphometrically. The de novo bone formed in OP implants was significantly less than in Con group when the implants contained no Sr, indicating that the BMP-induced osteogenesis was impaired in OP animals. Sr substitution as low as 0.5 mol% in apatite increased the bone volume in OP implants to levels comparable to that in the Con group, indicating a positive effect of Sr addition on the local bone formation in OP animals. In addition, more adipose tissue formed in parallel with the appearance of cartilage tissue in OP implants, suggesting that the differentiation potential of stem cell in OP animals may have shifted towards adipogenesis and chondrogenesis. From these results, we conclude that the use of Sr addition to enhance the bone growth surrounding implants in osteoporosis merits further study. The impaired bone healing capacity of osteoporotic patients might result in poor osteointegration and surgical failure in case implants are placed. In this study we aimed to enhance the bone formation around implants under such scenario by adding strontium as the stimulus. Different from other studies, the samples were loaded with rhBMP-2 and implanted at an ectopic site (spinal muscles of New Zealand

  20. Self-cleaning effects of acrylic resin containing fluoridated apatite-coated titanium dioxide.

    Science.gov (United States)

    Sawada, Tomofumi; Sawada, Tomoji; Kumasaka, Tomonari; Hamada, Nobushiro; Shibata, Takeshi; Nonami, Toru; Kimoto, Katsuhiko

    2014-03-01

    Specific materials when used in the manufacture of dentures can enhance the elimination of micro-organisms to promote oral hygiene. We used Candida albicans adhesion assays, methylene blue (MB)-decomposition tests and mechanical property tests to evaluate the photocatalytic properties of acrylic resin containing fluoridated apatite-coated titanium dioxide (FAp-TiO2 ) after treatment with ultraviolet A (UVA) irradiation. Conventional denture cleaning methods are unable to completely eliminate micro-organisms from dentures. Test specimens were prepared using acrylic resin containing three types of TiO2 powder [FAp-TiO2, titanium dioxide (TiO2 ) and hydroxyapatite-coated TiO2 (HAp-TiO2 )]; n = 96. In the adhesion assay, test specimens were incubated in a fungal suspension and subjected to UVA irradiation, and the number of attachments of C. albicans on the test specimens was counted. The MB-decomposition test and the three-point bending test were then performed to assess the photocatalytic effects of the FAp-TiO2 -containing acrylic resin. Fluoridated apatite-coated titanium dioxide-containing acrylic resin demonstrated superior effectiveness in inhibiting C. albicans adherence as well as in decomposing MB. In the three-point bending test, the resin showed a smaller decrease in flexural strength compared with TiO2 - or HAp-TiO2 -containing acrylic resin. Furthermore, UVA irradiation for 360 h did not significantly influence its flexural strength or elasticity modulus as compared with the control; this fulfils the requirements of International Organization for Standardization 1567:1999. Fluoridated apatite-coated titanium dioxide-containing acrylic resin is a clinically suitable material that promotes proper denture hygiene, particularly for elderly persons requiring nursing care or who have a decreased ability to perform normal activities of daily living. © 2013 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.

  1. Post late Paleozoic tectonism in the Southern Catalan Coastal Ranges (NE Spain), assessed by apatite fission tracks analysis

    NARCIS (Netherlands)

    Juez-Larré, J.; Andriessen, P.A.M.

    2002-01-01

    We report the first apatite fission-track thermochronologic data for 17 samples from the southern Catalan Coastal Ranges of NE Spain. Thermal histories of Carboniferous metasediments, Late Hercynian intrusions and Lower-Triassic Buntsandstein sediments from three tectonics blocks, Miramar, Prades

  2. 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.

  3. Thermal and exhumation history of Sakhalin Island (Russia) constrained by apatite U-Pb and fission track thermochronology

    Science.gov (United States)

    Glorie, Stijn; Alexandrov, Igor; Nixon, Angus; Jepson, Gilby; Gillespie, Jack; Jahn, Bor-Ming

    2017-08-01

    Sakhalin Island represents a key locality to study the tectonic evolution of the western Pacific. The island is located at the Amur-Okhotsk plate margin and records a complex thermotectonic history. Apatite double dating (U-Pb and fission track) and thermal history modelling were applied to three late Eocene granitoid massifs within central and southern Sakhalin: the Aniva, Okhotsk and Langeri complexes. Apatite U-Pb results yield consistent late Eocene (∼40-37 Ma) ages, suggesting rapid post-magmatic cooling. Apatite fission track results reveal bimodal age distributions with late Eocene - early Oligocene (∼38-33 Ma) and early Miocene (∼20-17 Ma) age populations that can be correlated with variations in Uranium and Chlorine concentrations. Thermal history modelling translates the AFT age bimodality into two-phase cooling histories. The timing of the early cooling phase (∼38-33 Ma) corresponds with the apatite U-Pb ages, indicating rapid cooling to at least ∼100 °C during the late Oligocene. The second cooling phase at ∼20-17 Ma cooled the samples to near-surface temperatures. Both cooling phases correspond with regional unconformities and subsequent accelerations in sedimentation rate, suggesting that cooling was a response to rapid exhumation. In addition, our data suggests that the studied terranes record differential exhumation with respect to the structural architecture. The Miocene exhumation pulse is coeval with the timing of transpressional fault displacement and the subsequent opening of the Kuril Basin.

  4. 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...

  5. Effect of wollastonite ceramics and bioactive glass on the formation of a bonelike apatite layer on a cobalt base alloy.

    Science.gov (United States)

    Cortés, D A; Medina, A; Escobedo, J C; Escobedo, S; López, M A

    2004-08-01

    A biomimetic method was used to promote a bioactive surface on a cobalt base alloy (ASTM F-75). The metallic substrates were alkali treated and some of the samples were subsequently heat treated. The treated samples were immersed in simulated body fluid (SBF) on granular particles of either bioactive glass or wollastonite. For comparative purposes, no bioactive system was used in some tests. Three different methods were used for the immersion of the samples in SBF: 1) 21 days in SBF, 2) 21 days in 1.5 SBF, and 3) 7 days in SBF followed by 14 days in 1.5 SBF (re-immersion method). A bonelike apatite layer was formed on all the samples placed on wollastonite and bioactive glass particles. The morphology of the apatite layer formed by using the re-immersion method and wollastonite closely resembled the existing bioactive systems. No apatite layer was observed on the samples treated without bioactive material and soaked for 21 days in SBF or 1.5 SBF, apart from the substrates treated by using the re-immersion method. The heat treatment delayed the apatite formation in all the cases studied. Copyright 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 341-346, 2004

  6. 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

  7. 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

  8. Comment on "Apatite: A new redox proxy for silicic magmas?" [Geochimica et Cosmochimica Acta 132 (2014) 101-119

    Science.gov (United States)

    Marks, Michael A. W.; Scharrer, Manuel; Ladenburger, Sara; Markl, Gregor

    2016-06-01

    Recently Miles et al. (2014) proposed that a negative correlation between oxygen fugacity (expressed as logfO2 and the Mn content of apatite from a range of intermediate to silicic igneous rocks could be used as an oxybarometer (Eq. (1)).

  9. 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

  10. 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

  11. Modeling hydroxylated nanosilica: Testing the performance of ReaxFF and FFSiOH force fields

    Science.gov (United States)

    Macià Escatllar, Antoni; Ugliengo, Piero; Bromley, Stefan T.

    2017-06-01

    We analyze the performance of the FFSiOH force field and two parameterisations of the ReaxFF force field for modeling hydroxylated nanoscale silica (SiO2). Such nanosystems are fundamental in numerous aspects of geochemistry and astrochemistry and also play a key role during the hydrothermal synthesis of technologically important nanoporous silicas (e.g., catalysts, absorbents, and coatings). We consider four aspects: structure, relative energies, vibrational spectra, and hydroxylation energies, and compare the results with those from density functional calculations employing a newly defined dataset (HND: Hydroxylated Nanosilica Dataset). The HND consists of three sets of (SiO2)16(H2O)N nanoparticles (NPs), each with a different degree of hydroxylation and each containing between 23 and 26 distinct isomers and conformers. We also make all HND reference data openly available. We further consider hydroxylated silica NPs of composition (SiO2)M(H2O)N with M = 4, 8, 16, and 24 and infinite surface slabs of amorphous silica, both with variable hydroxylation. For energetics, both ReaxFF and FFSiOH perform well for NPs with an intermediate degree of hydroxylation. For increased hydroxylation, the performance of FFSiOH begins to significantly decline. Conversely, for the lower degree of hydroxylation both parameterisations of ReaxFF do not perform well. For vibrational frequencies, FFSiOH performs particularly well and significantly better than ReaxFF. This feature also opens the door to inexpensively calculating Gibbs free energies of the hydroxylated nanosilica systems in order to efficiently correct density functional theory calculated electronic energies. We also show how some small changes to FFSiOH could improve its performance for higher degrees of hydroxylation.

  12. Non-linear hydroxyl radical formation rate in dispersions containing mixtures of pyrite and chalcopyrite particles

    Science.gov (United States)

    Kaur, Jasmeet; Schoonen, Martin A.

    2017-06-01

    The formation of hydroxyl radicals was studied in mixed pyrite-chalcopyrite dispersions in water using the conversion rate of adenine as a proxy for hydroxyl radical formation rate. Experiments were conducted as a function of pH, presence of phosphate buffer, surface loading, and pyrite-to-chalcopyrite ratio. The results indicate that hydroxyl radical formation rate in mixed systems is non-linear with respect to the rates in the pure endmember dispersions. The only exception is a set of experiments in which phosphate buffer is used. In the presence of phosphate buffer, the hydroxyl radical formation is suppressed in mixtures and the rate is close to that predicted based on the reaction kinetics of the pure endmembers. The non-linear hydroxyl radical formation in dispersions containing mixtures of pyrite and chalcopyrite is likely the result of two complementary processes. One is the fact that pyrite and chalcopyrite form a galvanic couple. In this arrangement, chalcopyrite oxidation is accelerated, while pyrite passes electrons withdrawn from chalcopyrite to molecular oxygen, the oxidant. The incomplete reduction of molecular oxygen leads to the formation of hydrogen peroxide and hydroxyl radical. The galvanic coupling appears to be augmented by the fact that chalcopyrite generates a significant amount of hydrogen peroxide upon dispersal in water. This hydrogen peroxide is then available for conversion to hydroxyl radical, which appears to be facilitated by pyrite as chalcopyrite itself produces only minor amounts of hydroxyl radical. In essence, pyrite is a ;co-factor; that facilitates the conversion of hydrogen peroxide to hydroxyl radical. This conversion reaction is a surface-mediated reaction. Given that hydroxyl radical is one of the most reactive species in nature, the formation of hydroxyl radicals in aqueous systems containing chalcopyrite and pyrite has implications for the stability of organic molecules, biomolecules, the viability of microbes, and

  13. 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

    Burpalinsky rare metal alkaline massif in the Northern Baikal folded zone in southern margin of Siberian Platform, is a of intrusion central type, created 287 Ma covering area of about 250 km2. It is composed of nepheline syenites and pulaskites grading to quartz syenites in the contacts. Veines and dykes are represented by shonkinites, sodalite syenite, leucocratic granophyres, alkali granites and numerous rare metal alkaline syenite pegmatites and two dykes of carbonatites. All rocks except for granites are cut by a large apatite-fluorite dyke rocks with mica and magnetite, which in turn is cut by alaskite granites dyke. The massif has been studied by A.M. Portnov, A.A. Ganzeev et al. (1992) Burpalinsky massif is highly enriched with trace elements, which are concentrated in pegmatite dykes. About 70 rare-metal minerals we found in massif. Zr-silicates: zircon, eudialyte, lovenite, Ti-lovenite, velerite, burpalite, seidozerite, Ca- seidozerite, Rosenbuschite, vlasovite, katapleite, Ca-katapleite, elpidite. Ti- minerals:- sphene, astrophyllite, ramsaite, Mn-neptunite bafertisite, chevkinite, Mn-ilmenite, pirofanite, Sr-perrerit, landauite, rutile, anatase, brookite; TR- minerals - loparite, metaloparite, britolite, rinkolite, melanocerite, bastnesite, parisite, ankilite, monazite, fluocerite, TR-apatite; Nb- minerals - pyrochlore, loparite. Other rare minerals leucophanite, hambergite, pyrochlore, betafite, torite, thorianite, tayniolite, brewsterite, cryolite and others. We have proposed a new scheme massif: shonkinites - nepheline syenites - alkaline syenite - quartz syenites - veined rocks: mariupolites, rare-metal pegmatites, apatite, fluorite rock alyaskite and alkaline granites and carbonatites (Sotnikova, 2009). Apatite-fluorite rocks are found in the central part of massif. This is a large vein body of 2 km length and a 20 m width cutting prevailing pulaskites. Previously, these rocks were regarded as hydrothermal low-temperature phase. New geological and

  14. Indirect selective laser sintering of apatite-wollostonite glass-ceramic.

    Science.gov (United States)

    Xiao, K; Dalgarno, K W; Wood, D J; Goodridge, R D; Ohtsuki, C

    2008-10-01

    This paper develops an indirect selective laser sintering (SLS) processing route for apatite-wollastonite (A-W) glass-ceramic, and shows that the processing route, which can create porous three-dimensional products suitable for bone implants or scaffolds, does not affect the excellent mechanical and biological properties of the glass-ceramic. 'Green parts' with fine integrity and well-defined shape have been produced from glass particles of single-size range or mixed-size ranges with acrylic binder in various ratios by weight. A subsequent heat treatment process has been developed to optimize the crystallization process, and an infiltration process has been explored to enhance mechanical strength. Three-point bending test results show flexural strengths of up to 102 MPa, dependent on porosity, and simulated body fluid (SBF) tests show that the laser sintered porous A-W has comparable biological properties to that of conventionally produced A-W.

  15. Structural, morphological and surface characteristics of two types of octacalcium phosphate-derived fluoride-containing apatitic calcium phosphates.

    Science.gov (United States)

    Shiwaku, Y; Anada, T; Yamazaki, H; Honda, Y; Morimoto, S; Sasaki, K; Suzuki, O

    2012-12-01

    Octacalcium phosphate (OCP) has been reported to stimulate bone regeneration during hydrolysis into hydroxyapatite (HA). The present study was designed to characterize structural, morphological and surface properties of fluoride-containing apatitic calcium phosphates (CaP) obtained through OCP hydrolysis or direct precipitation of OCP in the presence of 12-230ppm of fluoride (F). The products were characterized by chemical analysis, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transform infrared spectroscopy (FTIR) as well as measurements of surface area, solubility, osteoblastic activities and bovine serum albumin (BSA) adsorption. XRD analysis re-confirmed that both preparations yielded more apatitic CaP with a higher concentration of F. However, the co-precipitated products (CF-CaP) maintained the properties of OCP, in particular the solubility, whereas the hydrolysis products (HF-CaP) had the characteristics of fluoridated apatite. The crystals of plate-like OCP were changed to the crystals of rod-like CF-CaP and small irregular HF-CaP with the advance of the hydrolysis. The SAED analysis detected both OCP and apatite crystals even in the most hydrolyzed CF-CaP. Mouse bone marrow stromal ST-2 cells grew better on CF-CaP compared with HF-CaP. BSA adsorption was inhibited on HF-CaP more than on CF-CaP. These results show that OCP produces physicochemically distinct apatitic fluoridated CaP during hydrolysis, regarding the structure, the crystal morphology and the protein adsorption, depending on the fluoride introduction route, which provides biologically interesting material. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Surface reactivity of octacalcium phosphate-derived fluoride-containing apatite in the presence of polyols and fluoride.

    Science.gov (United States)

    Tsutsui, Sei; Anada, Takahisa; Shiwaku, Yukari; Tsuchiya, Kaori; Yamazaki, Hajime; Suzuki, Osamu

    2017-10-27

    The present study was designed to characterize co-precipitated fluoridated apatitic materials from octacalcium phosphate (OCP) precursor and to investigate their surface reactions with polyols including glycerol in the presence of fluoride ions. Laboratory-synthesized fluoridated apatite crystals (LS-FA) were obtained in a solution containing fluoride (F) from 25 to 500 ppm. LS-FAs and commercially available fluoroapatite (FA) and hydroxyapatite (HA) were characterized by physical techniques, such as X-ray diffraction. LS-FA obtained in the presence of 100 ppmF (100 ppm-LS-FA) had an apatitic structure, but its solubility was close to HA in a culture medium (α-MEM) despite the fact it contains over 3 wt % of F. 100 ppm-LS-FA, FA, and HA were then subjected to the human serum albumin (HSA) adsorption test at pH 7.4 (in a 150 mM Tris-HCl buffer) and the dissolution and re-mineralization experiments in the presence of xylitol, D-sorbitol, or glycerol, and F under acidic and neutral conditions. Adsorption affinity of HSA was estimated as highest for FA and lowest for LS-FA. LS-FA, FA, and HA were immersed in a lactic acid solution with the polyols and/or F ion-containing solution up to 200 ppm to analyze the dissolution behavior. LS-FA had the highest dissolution tendency in the conditions examined. Glycerol enhanced the dissolution of phosphate from apatite crystals in particular from LS-FA. The results suggest that the apatite crystals, obtained through the hydrolysis of OCP in the presence of F, provide a more reactive surface than FA or HA under physiological environments. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  17. Biomimetic self-assembly of apatite hybrid materials: from a single molecular template to bi-/multi-molecular templates.

    Science.gov (United States)

    Ma, Jun; Wang, Jianglin; Ai, Xin; Zhang, Shengmin

    2014-01-01

    The self-assembly of apatite and proteins is a critical process to induce the formation of the bones and teeth in vertebrates. Although hierarchical structures and biomineralization mechanisms of the mineralized tissues have been intensively studied, most researches focus on the self-assembly biomimetic route using one single-molecular template, while the natural bone is an outcome of a multi-molecular template co-assembly process. Inspired by such a mechanism in nature, a novel strategy based on multi-molecular template co-assembly for fabricating bone-like hybrid materials was firstly proposed by the authors. In this review article we have summarized the new trends from single-molecular template to bi-/multi-molecular template systems in biomimetic fabrication of apatite hybrid materials. So far, many novel apatite hybrid materials with controlled morphologies and hierarchical structures have been successfully achieved using bi-/multi-molecular template strategy, and are found to have multiple common features in comparison with natural mineralized tissues. The carboxyl, carbonyl and amino groups of the template molecules are identified to initiate the nucleation of calcium phosphate during the assembling process. For bi-/multi-molecular templates, the incorporation of multiple promotion sites for calcium and phosphate ions precisely enables to regulate the apatite nucleation from the early stage. The roles of acidic molecules and the synergetic effects of protein templates have been significantly recognized in recent studies. In addition, a specific attention is paid to self-assembling of apatite nanoparticles into ordered structures on tissue regenerative scaffolds due to their promising clinical applications ranging from implant grafts, coatings to drug and gene delivery. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. 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.

  19. The influence of burial heating on the (U-Th)/He system in apatite: Grand Canyon case study

    Science.gov (United States)

    Fox, Matthew; Shuster, David L.

    2014-07-01

    Thermochronological data can constrain the cooling paths of rocks exhumed through the uppermost 1-2 km of earth's crust, and have thus been pivotal in illuminating topographic development over timescales >0.1 Ma. However, in some cases, different methods have led to conflicting conclusions about timing of valley-scale exhumation. Here, we investigate the case of Western Grand Canyon, USA, where different thermochronological datasets have been interpreted to record very different timings of canyon incision (∼70 Ma versus ∼5 Ma). We present a method to assess key assumptions in these constraints and demonstrate that burial heating conditions of basement rocks in the Mesozoic can result in incomplete annealing of radiation damage in apatite. In turn, this has a dramatic effect on the temperature sensitivity of the apatite (U-Th)/He system and its ability to record post-burial exhumation. The possibility of incomplete annealing resolves the apparent conflict in time-temperature paths inferred over the last 70 Ma, although it requires temperatures during burial that are lower than predicted by apatite fission track data. A refinement of parameters that prescribe the kinetics of damage annealing and related control on 4He diffusivity in apatite would account for this discrepancy, specifically if alpha recoil damage anneals at a lower rate than fission tracks at a given temperature. These effects will be important for any application of the apatite (U-Th)/He system in geologic settings that experienced prolonged residence (>10 Ma) between 50-150 °C; the approaches developed here provide means to assess these effects.

  20. Recurrent Stroke: The Value of the CHA2DS2VASc Score and the Essen Stroke Risk Score in a Nationwide Stroke Cohort.

    Science.gov (United States)

    Andersen, Søren Due; Gorst-Rasmussen, Anders; Lip, Gregory Y H; Bach, Flemming W; Larsen, Torben Bjerregaard

    2015-09-01

    The CHA2DS2VASc score and the Essen Stroke Risk Score are respectively used for risk stratification in patients with atrial fibrillation and in patients with cerebrovascular incidents. We aimed to test the ability of the 2 scores to predict stroke recurrence, death, and cardiovascular events (stroke, transient ischemic attack, myocardial infarction, or arterial thromboembolism) in a nationwide Danish cohort study, among patients with incident ischemic stroke and no atrial fibrillation. We conducted a registry-based study in patients with incident ischemic stroke and no atrial fibrillation. Patients were stratified according to the CHA2DS2VASc score and the Essen Stroke Risk Score and were followed up until stroke recurrence or death. We estimated stratified incidence rates and hazard ratios and calculated the cumulative risks. 42 182 patients with incident ischemic stroke with median age 70.1 years were included. The overall 1-year incidence rates of recurrent stroke, death, and cardiovascular events were 3.6%, 10.5%, and 6.7%, respectively. The incidence rates, the hazard ratios, and the cumulative risk of all outcomes increased with increasing risk scores. C-statistics for both risk scores were around 0.55 for 1-year stroke recurrence and cardiovascular events and correspondingly for death around 0.67 for both scores. In this cohort of non-atrial fibrillation patients with incident ischemic stroke, increasing CHA2DS2VASc score and Essen Stroke Risk Score was associated with increasing risk of recurrent stroke, death, and cardiovascular events. Their discriminatory performance was modest and further refinements are required for clinical application. © 2015 American Heart Association, Inc.

  1. Free DNA precipitates calcium phosphate apatite crystals in the arterial wall in vivo.

    Science.gov (United States)

    Coscas, Raphaël; Bensussan, Marie; Jacob, Marie-Paule; Louedec, Liliane; Massy, Ziad; Sadoine, Jeremy; Daudon, Michel; Chaussain, Catherine; Bazin, Dominique; Michel, Jean-Baptiste

    2017-04-01

    The arterial wall calcium score and circulating free DNA levels are now used in clinical practice as biomarkers of cardiovascular risk. Calcium phosphate apatite retention in the arterial wall necessitates precipitation on an anionic platform. Here, we explore the role of tissue-free DNA as such a platform. The first step consisted of histological observation of samples from human and rat calcified arteries. Various stains were used to evaluate colocalization of free DNA with calcified tissue (alizarin red, fluorescent Hoechst, DNA immunostaining and TUNEL assay). Sections were treated by EDTA to reveal calcification background. Secondly, a rat model of vascular calcifications induced by intra-aortic infusions of free DNA and elastase + free DNA was developed. Rat aortas underwent a micro-CT for calcium score calculation at 3 weeks. Rat and human calcifications were qualitatively characterized using μFourier Transform Infrared Spectroscopy (μFTIR) and Field Emission-Scanning Electron Microscopy (FE-SEM). Our histological study shows colocalization of calcified arterial plaques with free DNA. In the intra-aortic infusion model, free DNA was able to penetrate into the arterial wall and induce calcifications whereas no microscopic calcification was seen in control aortas. The calcification score in the elastase + free DNA group was significantly higher than in the control groups. Qualitative evaluation with μFTIR and FE-SEM demonstrated typical calcium phosphate retention in human and rat arterial specimens. This translational study demonstrates that free DNA could be involved in arterial calcification formation by precipitating calcium phosphate apatite crystals in the vessel wall. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Synthesis of functionally graded bioactive glass-apatite multistructures on Ti substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tanaskovic, D.; Jokic, B. [Faculty of Technology and Metallurgy, Karnegijeva 4, 11000 Belgrade (Serbia); Socol, G.; Popescu, A. [National Institute for Lasers, Plasma and Radiation Physics, Box MG-54, Bucharest-Magurele, RO-77125 (Romania); Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Box MG-54, Bucharest-Magurele, RO-77125 (Romania)], E-mail: ion.mihailescu@inflpr.ro; Petrovic, R.; Janackovic, Dj. [Faculty of Technology and Metallurgy, Karnegijeva 4, 11000 Belgrade (Serbia)

    2007-12-15

    Functionally graded glass-apatite multistructures were synthesized by pulsed laser deposition on Ti substrates. We used sintered targets of hydroxyapatite Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, or bioglasses in the system SiO{sub 2}-Na{sub 2}O-K{sub 2}O-CaO-MgO-P{sub 2}O{sub 5} with SiO{sub 2} content of either 57 wt.% (6P57) or 61 wt.% (6P61). A UV KrF* ({lambda} = 248 nm, {tau} > 7 ns) excimer laser source was used for the multipulse laser ablation of the targets. The hydroxyapatite thin films were obtained in H{sub 2}O vapors, while the bioglass layers were deposited in O{sub 2}. Thin films of 6P61 were deposited in direct contact with Ti, because Ti and this glass have similar thermal expansion behaviors, which ensure good bioglass adhesion to the substrate. This glass, however, is not bioactive, so yet more depositions of 6P57 bioglass and/or hydroxyapatite thin films were performed. All structures with hydroxyapatite overcoating were post-treated in a flux of water vapors. The obtained multistructures were characterized by various techniques. X-ray investigations of the coatings found small amounts of crystalline hydroxyapatite in the outer layers. The scanning electron microscopy analyses revealed homogeneous coatings with good adhesion to the Ti substrate. Our studies showed that the multistructures we had obtained were compatible with further use in biomimetic metallic implants with glass-apatite coating applications.

  4. 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.

  5. CHADS2 score has a better predictive value than CHA2DS2-VASc score in elderly patients with atrial fibrillation

    Directory of Open Access Journals (Sweden)

    Xing YL

    2016-07-01

    Full Text Available Yunli Xing, Qing Ma, Xiaoying Ma, Cuiying Wang, Dai Zhang, Ying Sun Department of Geriatrics and Gerontology, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China Aim: The study aims to compare the ability of CHA2DS2-VASc (defined as congestive heart failure, hypertension, age ≥75 years [two scores], type 2 diabetes mellitus, previous stroke, transient ischemic attack, or thromboembolism [TE] [doubled], vascular disease, age 65–74 years, and sex category and CHADS2 (defined as congestive heart failure, hypertension, age ≥75 years, type 2 diabetes mellitus, previous stroke [doubled] scores to predict the risk of ischemic stroke (IS or TE among patients with nonvalvular atrial fibrillation (NVAF.Methods: A total of 413 patients with NVAF aged ≥65 years, and not on oral anticoagulants for the previous 6 months, were enrolled in the study. The predictive value of the CHA2DS2-VASc and CHADS2 scores for IS/TE events was evaluated by the Kaplan–Meier method.Results: During a follow-up period of 1.99±1.29 years, 104 (25.2% patients died and 59 (14.3% patients developed IS/TE. The CHADS2 score performed better than the CHA2DS2-VASc score in predicting IS/TE as assessed by c-indexes (0.647 vs 0.615, respectively; P<0.05. Non-CHADS2 risk factors, such as vascular disease and female sex, were not found to be predictive of IS/TE (hazard ratio 1.518, 95% CI: 0.832–2.771; hazard ratio 1.067, 95% CI: 0.599–1.899, respectively. No differences in event rates were found in patients with the CHADS2 scores of 1 and 2 (7.1% vs 7.8%. It was observed that patients with a CHADS2 score of ≥3 were most in need of anticoagulation therapy.Conclusion: In patients with NVAF aged ≥65 years, the CHADS2 score was found to be significantly better in predicting IS/TE events when compared to the CHA2DS2-VASc score. Patients with a CHADS2 score of ≥3 were associated with high risk of IS/TE events. Keywords: NVAF

  6. Contribution au pilotage des processus d'une chaîne logistique Etude de cas du processus approvisionnement d'une PME marocaine

    OpenAIRE

    Naciri, Oumaima; Alami, Ayoub; Herrou, Brahim

    2015-01-01

    International audience; Le processus approvisionnement est un des acteurs d'une chaîne logistique qui doit être maîtrisé du fait de son poids conséquent sur la performance de tout les processus de l'entreprise. Cette maîtrise nécessite une mise en œuvre de bons outils de mesure. Les indicateurs constituent un élément essentiel de la maîtrise des processus à la condition que l'ensemble des indicateurs mis en place permette de lancer des actions correctives et de prendre des décisions cohérente...

  7. Oxygen isotopes reveal crustal contamination and a large, still partially molten magma chamber in Chaîne des Puys (French Massif Central)

    Science.gov (United States)

    France, Lydéric; Demacon, Mickael; Gurenko, Andrey A.; Briot, Danielle

    2016-09-01

    The two main magmatic properties associated with explosive eruptions are high viscosity of silica-rich magmas and/or high volatile contents. Magmatic processes responsible for the genesis of such magmas are differentiation through crystallization, and crustal contamination (or assimilation) as this process has the potential to enhance crystallization and add volatiles to the initial budget. In the Chaîne des Puy series (French Massif Central), silica- and H2O-rich magmas were only emitted during the most recent eruptions (ca. 6-15 ka). Here, we use in situ measurements of oxygen isotopes in zircons from two of the main trachytic eruptions from the Chaîne des Puys to track the crustal contamination component in a sequence that was previously presented as an archetypal fractional crystallization series. Zircons from Sarcoui volcano and Puy de Dôme display homogeneous oxygen isotope compositions with δ18O = 5.6 ± 0.25‰ and 5.6 ± 0.3‰, respectively, and have therefore crystallized from homogeneous melts with δ18Omelt = 7.1 ± 0.3‰. Compared to mantle derived melts resulting from pure fractional crystallization (δ18Odif.mant. = 6.4 ± 0.4‰), those δ18Omelt values are enriched in 18O and support a significant role of crustal contamination in the genesis of silica-rich melts in the Chaîne des Puys. Assimilation-fractional-crystallization models highlight that the degree of contamination was probably restricted to 5.5-9.5% with Rcrystallization/Rassimilation varying between 8 and 14. The very strong intra-site homogeneity of the isotopic data highlights that magmas were well homogenized before eruption, and consequently that crustal contamination was not the trigger of silica-rich eruptions in the Chaîne des Puys. The exceptionally strong inter-site homogeneity of the isotopic data brings to light that Sarcoui volcano and Puy de Dôme were fed by a single large magma chamber. Our results, together with recent thermo-kinetic models and an experimental

  8. Une industrie normée ? Gouvernement par les normes, jeu sur les normes et internationalisation des chaînes de valeur dans le secteur pharmaceutique

    OpenAIRE

    Labrousse, Agnès

    2016-01-01

    Dans le secteur pharmaceutique, les normes sont présentes à chaque maillon de la chaîne de valeur. Ces normes, loin d’être de simples énoncés scientifiques ou techniques socialement inertes sont des construits politiques et sociaux dont se saisissent des acteurs divers au pouvoir variable. Est examiné ici, dans une perspective d’économie politique des normes, le cycle des normes pharmaceutiques (bonnes pratiques cliniques, de laboratoire et de fabrication), de leur négociation à leur mise en ...

  9. Peroxidase Can Perform the Hydroxylation Step in the "oxidative Cascade" during Oxidation of Tea Catechins

    NARCIS (Netherlands)

    Verloop, Annewieke J.W.; Vincken, Jean Paul; Gruppen, Harry

    2016-01-01

    The formation of black tea thearubigins involves at least two of the following oxidation steps: (i) oligomerization, (ii) rearrangement, and (iii) hydroxylation. The first two are mainly catalyzed by polyphenol oxidase (PPO), whereas the enzyme responsible for hydroxylation has not yet been

  10. The effect of hydroxylation of linoleoyl amides on their cannabinomimetic properties

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Stelt, M. van der; Paoletti, A.M.; Maccarrone, M.; Nieuwenhuizen, W.F.; Bagetta, G.; Veldink, G.A.; Finazzi Agrò, A.

    1997-01-01

    As yet, the physiological significance of hydroxylation of anandamide and linoleoyl amides is unknown. Therefore, we investigated whether hydroxylation of ODNHEtOH and ODNH2 influences their binding abilities to the CB-1 receptor and whether it alters their reactivity towards a fatty acid amide

  11. Hydroxylation of the Herbicide Isoproturon by Fungi Isolated from Agricultural soil

    DEFF Research Database (Denmark)

    Rønhede, S.; Jensen, Bo; Rosendahl, Søren

    2005-01-01

    of these hydroxylated metabolites in soils treated with isoproturon. Isolates of Mortierella sp. strain Gr4, Phoma cf. eupyrena Gr61, and Alternaria sp. strain Gr174 hydroxylated isoproturon at the first position of the isopropyl side chain, yielding N-(4-(2-hydroxy-1-methylethyl)phenyl)-N',N'-dimethylurea, while Mucor...

  12. Mechanism of aromatic hydroxylation of lidocaine at a Pt electrode under acidic conditions

    NARCIS (Netherlands)

    Gul, Turan; Bischoff, Rainer; Permentier, Hjalmar P.

    2017-01-01

    Aromatic hydroxylation reactions, which are mainly catalyzed by cytochrome P450 (CYP) enzymes in vivo, are some of the most important reactions of Phase I metabolism, because insertion of a hydroxyl group into a lipophilic drug compound increases its hydrophilicity and prepares it for subsequent

  13. Solvent effects and improvements in the deoxyribose degradation assay for hydroxyl radical-scavenging.

    Science.gov (United States)

    Li, Xican

    2013-12-01

    The deoxyribose degradation assay is widely used to evaluate the hydroxyl (OH) radical-scavenging ability of food or medicines. We compared the hydroxyl radical-scavenging activity of 25 antioxidant samples prepared in ethanol solution with samples prepared after removing the ethanol (residue). The data suggested that there was an approximately 9-fold difference between assay results for the ethanol solution and residue samples. This indicated a strong alcoholic interference. To further study the mechanism, the scavenging activities of 18 organic solvents (including ethanol) were measured by the deoxyribose assay. Most pure organic solvents (especially alcohols) could effectively scavenge hydroxyl radicals. As hydroxyl radicals have extremely high reactivities, they will quickly react with surrounding solvent molecules. This shows that any organic solvent should be completely evaporated before measurement. The proposed method is regarded as a reliable hydroxyl radical-scavenging assay, suitable for all types of antioxidants. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Coordinated Hard Sphere Mixture (CHaSM): A fast approximate model for oxide and silicate melts at extreme conditions

    Science.gov (United States)

    Wolf, A. S.; Asimow, P. D.; Stevenson, D. J.

    2015-12-01

    Recent first-principles calculations (e.g. Stixrude, 2009; de Koker, 2013), shock-wave experiments (Mosenfelder, 2009), and diamond-anvil cell investigations (Sanloup, 2013) indicate that silicate melts undergo complex structural evolution at high pressure. The observed increase in cation-coordination (e.g. Karki, 2006; 2007) induces higher compressibilities and lower adiabatic thermal gradients in melts as compared with their solid counterparts. These properties are crucial for understanding the evolution of impact-generated magma oceans, which are dominated by the poorly understood behavior of silicates at mantle pressures and temperatures (e.g. Stixrude et al. 2009). Probing these conditions is difficult for both theory and experiment, especially given the large compositional space (MgO-SiO2-FeO-Al2O3-etc). We develop a new model to understand and predict the behavior of oxide and silicate melts at extreme P-T conditions (Wolf et al., 2015). The Coordinated Hard Sphere Mixture (CHaSM) extends the Hard Sphere mixture model, accounting for the range of coordination states for each cation in the liquid. Using approximate analytic expressions for the hard sphere model, this fast statistical method compliments classical and first-principles methods, providing accurate thermodynamic and structural property predictions for melts. This framework is applied to the MgO system, where model parameters are trained on a collection of crystal polymorphs, producing realistic predictions of coordination evolution and the equation of state of MgO melt over a wide P-T range. Typical Mg-coordination numbers are predicted to evolve continuously from 5.25 (0 GPa) to 8.5 (250 GPa), comparing favorably with first-principles Molecular Dynamics (MD) simulations. We begin extending the model to a simplified mantle chemistry using empirical potentials (generally accurate over moderate pressure ranges, consuming classical MD calculations. This approach also sheds light on the universality

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

    OpenAIRE

    S. Klemme; T. John; M. Wessels; C. Kusebauch; J. Berndt; A. Rohrbach; P. Schmidt-Beurmann

    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 trac...

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

    Science.gov (United States)

    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

  17. Partitioning behavior of chlorine and fluorine in the system apatite melt fluid. II: Felsic silicate systems at 200 MPa

    Science.gov (United States)

    Webster, James D.; Tappen, Christine M.; Mandeville, Charles W.

    2009-02-01

    Hydrothermal experiments were conducted to determine the partitioning of Cl between rhyolitic to rhyodacitic melts, apatite, and aqueous fluid(s) and the partitioning of F between apatite and these melts at ca. 200 MPa and 900-924 °C. The number of fluid phases in our experiments is unknown; they may have involved a single fluid or vapor plus saline liquid. The partitioning behavior of Cl between apatite and melt is non-Nernstian and is a complex function of melt composition and the Cl concentration of the system. Values of DClapat/melt (wt. fraction of: Cl in apatite/Cl in melt) vary from 1 to 4.5 and are largest when the Cl concentrations of the melt are at or near the Cl-saturation value of the melt. The Cl-saturation concentrations of silicate melts are lowest in evolved, silica-rich melts, so with elevated Cl concentrations in a system and with all else equal, the maximum values of DClapat/melt occur with the most felsic melt. In contrast, values of DFapat/melt range from 11 to 40 for these felsic melts, and many of these are an order of magnitude greater than those applying to basaltic melts at 200 MPa and 1066-1150 °C. The Cl concentration of apatite is a simple and linear function of the concentration of Cl in fluid. Values of DClfluid/apat for these experiments range from 9 to 43, and some values are an order of magnitude greater than those determined in 200-MPa experiments involving basaltic melts at 1066-1150 °C. In order to determine the concentrations and interpret the behavior of volatile components in magmas, the experimental data have been applied to the halogen concentrations of apatite grains from chemically evolved rocks of Augustine volcano, Alaska; Krakatau volcano, Indonesia; Mt. Pinatubo, Philippines; Mt. St. Helens, Washington; Mt. Mazama, Oregon; Lascar volcano, Chile; Santorini volcano, Greece, and the Bishop Tuff, California. The F concentrations of these magmas estimated from apatite-melt equilibria range from 0.06 to 0.12 wt% and are

  18. Cellulose based hybrid hydroxylated adducts for polyurethane foams

    Science.gov (United States)

    De Pisapia, Laura; Verdolotti, Letizia; Di Mauro, Eduardo; Di Maio, Ernesto; Lavorgna, Marino; Iannace, Salvatore

    2012-07-01

    Hybrid flexible polyurethane foams (HPU) were synthesized by using a hybrid hydroxilated adduct (HHA) based on renewable resources. In particular the HHA was obtained by dispersing cellulose wastes in colloidal silica at room temperature, pressure and humidity. The colloidal silica was selected for its ability of modifying the cellulose structure, by inducing a certain "destructurization" of the crystalline phase, in order to allow cellulose to react with di-isocyanate for the final synthesis of the polyurethane foam. In fact, cellulose-polysilicate complexes are engaged in the reaction with the isocyanate groups. This study provides evidence of the effects of the colloidal silica on the cellulose structure, namely, a reduction of the microfiber cellulose diameter and the formation of hydrogen bonds between the polysilicate functional groups and the hydroxyl groups of the cellulose, as assessed by IR spectroscopy and solid state NMR. The HHA was added to a conventional polyol in different percentages (between 5 and 20%) to synthesize HPU in presence of catalysts, silicone surfactant and diphenylmethane diisocyanate (MDI). The mixture was expanded in a mold and cured for two hours at room temperature. Thermal analysis, optical microscopy and mechanical tests were performed on the foams. The results highlighted an improvement of thermal stability and a decrease of the cell size with respect neat polyurethane foam. Mechanical tests showed an improvement of the elastic modulus and of the damping properties with increasing HHA amount.

  19. An absolute calibration for gas-phase hydroxyl measurements.

    Science.gov (United States)

    Hard, Thomas M; George, Linda A; O'Brien, Robert J

    2002-04-15

    We describe a new method of calibrating tropospheric hydroxyl (OH) instruments. Ozone-alkene mixtures produce steady-state OH radical concentrations. The steady state is governed by competition between OH production in the reaction of ozone with the alkene and OH removal by reactions with the alkene, ozone, and the reactor wall. In a flowtube reactor transporting an ozone-alkene mixture, the OH wall loss rate can be measured by varying the alkene concentration. Delivery of the reaction mixture to the sampling entry of an atmospheric OH measurement instrument provides an absolute calibration of the instrument's response to OH. The present precision of calibration is +/-8% (1-sigma), based on reproducibility over a wide range of ozone concentrations. The accuracy (+/-43%) is limited by uncertainties in kinetic rate coefficients and OH yield, which can be improved. The calibration requires no photon flux measurements or lamp-dependent absorption coefficients, which have inherent, variable, systematic uncertainties, and it has been tested in field experiments.

  20. Observational evidence for interhemispheric hydroxyl-radical parity.

    Science.gov (United States)

    Patra, P K; Krol, M C; Montzka, S A; Arnold, T; Atlas, E L; Lintner, B R; Stephens, B B; Xiang, B; Elkins, J W; Fraser, P J; Ghosh, A; Hintsa, E J; Hurst, D F; Ishijima, K; Krummel, P B; Miller, B R; Miyazaki, K; Moore, F L; Mühle, J; O'Doherty, S; Prinn, R G; Steele, L P; Takigawa, M; Wang, H J; Weiss, R F; Wofsy, S C; Young, D

    2014-09-11

    The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere. The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane. It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4, 7-10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004-2011 the model predicts an annual mean NH-SH gradient of methyl chloroform that is a tight linear function of the modelled NH/SH ratio in annual mean OH. We estimate a NH/SH OH ratio of 0.97 ± 0.12 during this time period by optimizing global total emissions and mean OH abundance to fit methyl chloroform data from two surface-measurement networks and aircraft campaigns. Our findings suggest that top-down emission estimates of reactive species such as nitrogen oxides in key emitting countries in the NH that are based on a NH/SH OH ratio larger than 1 may be overestimated.

  1. [Emission spectra of hydroxyl radical generated in air corona discharge].

    Science.gov (United States)

    Sun, Ming; Wu, Yan; Zhang, Jia-Liang; Li, Jie; Wang, Ning-Hui; Wu, Jiang; Shang, Ke-Feng

    2005-01-01

    In this paper, the relative emission intensity of the 309 nm transition band of hydroxyl radical (OH) was measured by a CCD imaging spectrometer in a pin-plane corona discharge scheme of one atmosphere pressure air injected with unsaturated water vapor from the central hole of the used pins. The influences of several factors on the OH radical production were investigated by relative emission intensity measurement. The production of OH radical increased with a limited increment of water vapor concentration in the mixed gas. Compared with positive DC corona discharges, more OH radicals were generated in positive pulsed corona discharges and less in negative DC corona discharges. The spatial distribution of OH radical production was also observed. Most OH radicals were produced within the range of 5 mm off the discharge pin electrode. In conclusion, this means of optical emission spectroscopy, compared with more sophisticated laser fluorescence measurements used for plasma OH production diagnostics investigation, is simpler and more effective for characterizing the OH radical potential for pollutant oxidation.

  2. Beta transmutations in apatites with ferric iron as an electron acceptor - implication for nuclear waste form development.

    Science.gov (United States)

    Yao, Ge; Zhang, Zelong; Wang, Jianwei

    2017-09-27

    Apatite-structured materials have been considered for the immobilization of a number of fission products from reprocessing nuclear fuel because of their chemical durability as well as compositional and structural flexibility. It is hypothesized that the effect of beta decay on the stability can be mitigated by introducing an appropriate electron acceptor at the neighboring sites in the structure. The decay series 137 Cs → 137 Ba and 90 Sr → 90 Y → 90 Zr were investigated using a spin-polarized DFT approach to test the hypothesis. Apatites with compositions of Ca 10 (PO 4 ) 6 F 2 and Ca 4 Y 6 (SiO 4 ) 6 F 2 were selected as model systems for the incorporation of radionuclides Cs and Sr, respectively. Ferric iron was introduced in the structure as an electron acceptor. Electron density of states, crystal and defect structures, and energies before and after beta decay were calculated. The calculated electron density of states suggests that the extra electron is localized at the ferric iron, which changes its oxidation state and becomes ferrous iron. The crystal and defect structures were analyzed based on the volume, lattice parameters, radial distribution functions, metal cation to coordinating oxygen distances, and the metaprism twist angle of the apatite crystal structure. The results show that there are minor changes in the crystal and defect structures of CsFeCa 8 (PO 4 ) 6 F 2 with Cs + and Fe 3+ substitutions undergoing the Cs → Ba transmutation, and of Ca 3 SrY 4 Fe 2 (SiO 4 ) 6 F 2 with Sr 2+ and Fe 3+ substitutions undergoing the Sr → Y → Zr transmutations. The last decay change, from Y 3+ → Zr 4+ , causes relatively larger changes in the local defect structure around Zr involving the coordination environment but the change is not significant to the crystal structure. The results on calculated cohesive energy suggest that the transmutations Cs + → Ba 2+ and Sr 2+ → Y 3+ → Zr 4+ in both apatite compositions are energetically favorable

  3. Coumarin-fused coumarin: antioxidant story from N,N-dimethylamino and hydroxyl groups.

    Science.gov (United States)

    Xi, Gao-Lei; Liu, Zai-Qun

    2015-04-08

    Two coumarin skeletons can form chromeno[3,4-c]chromene-6,7-dione by sharing with the C ═ C in lactone. The aim of the present work was to explore the antioxidant effectiveness of the coumarin-fused coumarin via six synthetic compounds containing hydroxyl and N,N-dimethylamino as the functional groups. The abilities to quench 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(+•)), 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and galvinoxyl radical revealed that the rate constant for scavenging radicals was related to the amount of hydroxyl group in the scaffold of coumarin-fused coumarin. But coumarin-fused coumarin was able to inhibit DNA oxidations caused by (•)OH, Cu(2+)/glutathione (GSH), and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) even in the absence of hydroxyl group. In particular, a hydroxyl and an N,N-dimethylamino group locating at different benzene rings increased the inhibitory effect of coumarin-fused coumarin on AAPH-induced oxidation of DNA about 3 times higher than a single hydroxyl group, whereas N,N-dimethylamino-substituted coumarin-fused coumarin possessed high activity toward (•)OH-induced oxidation of DNA without the hydroxyl group contained. Therefore, the hydroxyl group together with N,N-dimethylamino group may be a novel combination for the design of coumarin-fused heterocyclic antioxidants.

  4. Measurement of hydroxyl radical production in ultrasonic aqueous solutions by a novel chemiluminescence method.

    Science.gov (United States)

    Hu, Yufei; Zhang, Zhujun; Yang, Chunyan

    2008-07-01

    Measurement methods for ultrasonic fields are important for reasons of safety. The investigation of an ultrasonic field can be performed by detecting the yield of hydroxyl radicals resulting from ultrasonic cavitations. In this paper, a novel method is introduced for detecting hydroxyl radicals by a chemiluminescence (CL) reaction of luminol-hydrogen peroxide (H2O2)-K5[Cu(HIO6)2](DPC). The yield of hydroxyl radicals is calculated directly by the relative CL intensity according to the corresponding concentration of H2O2. This proposed CL method makes it possible to perform an in-line and real-time assay of hydroxyl radicals in an ultrasonic aqueous solution. With flow injection (FI) technology, this novel CL reaction is sensitive enough to detect ultra trace amounts of H2O2 with a limit of detection (3sigma) of 4.1 x 10(-11) mol L(-1). The influences of ultrasonic output power and ultrasonic treatment time on the yield of hydroxyl radicals by an ultrasound generator were also studied. The results indicate that the amount of hydroxyl radicals increases with the increase of ultrasonic output power (measured by calculating the yield of hydroxyl radicals.

  5. Reply to comment by Marks et al. (2016) on "Apatite: A new redox proxy for silicic magmas?" [Geochimica et Cosmochimica Acta 132 (2014) 101-119

    Science.gov (United States)

    Miles, Andrew; Graham, Colin; Hawkesworth, Chris; Gillespie, Martin; Hinton, Richard; Bromiley, Geoffrey; Emmac

    2016-06-01

    Marks et al. (2016) investigate the applicability of the Mn-in-apatite oxybarometer proposed by Miles et al. (2014) across a range of magma compositions using published data on well-characterised samples. The authors show that for magma compositions outside of the calc-alkaline and intermediate to silicic range used in the preliminary calibration, fO2 values calculated from Mn-in-apatite vary significantly from independently constrained estimates. These data are used to reiterate our warnings that other controls that are additional to oxygen fugacity are likely to affect Mn partitioning into apatite in some rock types, and particularly so in magmas that lie outside of the range of compositions and conditions used in the calibration. Marks et al. (2016) highlight that temperature may have an especially important effect on Mn partitioning in apatite in some rock types.

  6. 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

  7. The Calcium Phosphate Matrix of FGF-2-Apatite Composite Layers Contributes to Their Biological Effects

    Directory of Open Access Journals (Sweden)

    Hirotaka Mutsuzaki

    2014-06-01

    Full Text Available The purpose of the present study was to fabricate fibroblast growth factor (FGF-2-apatite composite layers on titanium (Ti pins in one step at 25 °C using a supersaturated calcium phosphate (CaP solution, and to evaluate the physicochemical characteristics and biological effects of the coated Ti pins compared with coated Ti pins fabricated at 37 °C. Ti pins were immersed in a supersaturated CaP solution containing 0.5, 1.0, or 2.0 µg/mL FGF-2 at 25 °C for 24 h (25F0.5, 25F1.0, and 25F2.0 or containing 4.0 µg/mL FGF-2 at 37 °C for 48 h (37F4.0. Except for the 25F0.5, the chemical compositions and the mitogenic activity levels of FGF-2 of the composite layers formed by these two methods were similar, except for the Ca/P molar ratio, which was markedly smaller at 25 °C (1.55–1.56 ± 0.01–0.02, p = 0.0008–0.0045 than at 37 °C (1.67 ± 0.11. Thus, either the apatite was less mature or the amount of amorphous calcium phosphate was higher in the composite layer formed at 25 °C. In vivo, the pin tract infection rate by visual inspection for 37F4.0 (45% was lower than that for 25F1.0 (80%, p = 0.0213, and the rate of osteomyelitis for 37F4.0 (35% was lower than that for 25F0.5 (75%, p = 0.0341. The extraction torque for 37F4.0 (0.276 ± 0.117 Nm was higher than that for 25F0.5 (0.192 ± 0.117 Nm, p = 0.0142 and that for 25F1.0 (0.176 ± 0.133 Nm, p = 0.0079. The invasion rate of S. aureus for 37F4.0 (35% was lower than that for 25F0.5 (75%, p = 0.0110. On the whole, the FGF-2-apatite composite layer formed at 25 °C tended to be less effective at improving fixation strength in the bone-pin interface and resisting pin tract infections. These results suggest that the chemistry of the calcium phosphate matrix that embeds FGF-2, in addition to FGF-2 content and activity, has a significant impact on composite infection resistance and fixation strength.

  8. Raman spectral, elemental, crystallinity, and oxygen-isotope variations in conodont apatite during diagenesis

    Science.gov (United States)

    Zhang, Lei; Cao, Ling; Zhao, Laishi; Algeo, Thomas J.; Chen, Zhong-Qiang; Li, Zhihong; Lv, Zhengyi; Wang, Xiangdong

    2017-08-01

    Conodont apatite has long been used in paleoenvironmental studies, often with minimal evaluation of the influence of diagenesis on measured elemental and isotopic signals. In this study, we evaluate diagenetic influences on conodonts using an integrated set of analytical techniques. A total of 92 points in 19 coniform conodonts from Ordovician marine units of South China were analyzed by micro-laser Raman spectroscopy (M-LRS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), high-resolution X-ray microdiffraction (HXRD), and secondary ion mass spectrometry (SIMS). Each conodont element was analyzed along its full length, including the albid crown, hyaline crown, and basal body, in either a whole specimen (i.e., reflecting the composition of its outer layer) or a split specimen (i.e., reflecting the composition of its interior). In the conodonts of this study, the outer surfaces consist of hydroxyfluorapatite and the interiors of strontian hydroxyfluorapatite. Ionic substitutions resulted in characteristic Raman spectral shifts in the position (SS1) and width (SS2) of the ν1-PO43- stretching band. Although multiple elements were enriched (Sr2+, Mg2+) and depleted (Fe3+, Mn2+, Ca2+) during diagenesis, geochemical modeling constraints and known Raman spectral patterns suggest that Sr uptake was the dominant influence on diagenetic redshifts of SS1. All study specimens show lower SS2 values than modern bioapatite and synthetic apatite, suggesting that band width decreases with time in ancient bioapatite, possibly through an annealing process that produces larger, more uniform crystal domains. Most specimens consist mainly of amorphous or poorly crystalline apatite, which is inferred to represent the original microstructure of conodonts. In a subset of specimens, some tissues (especially albid crown) exhibit an increased degree of crystallinity developed through aggrading neomorphism. However, no systematic relationship was observed between

  9. Hydroxyl-dependent Evolution of Oxygen Vacancies Enables the Regeneration of BiOCl photocatalyst

    KAUST Repository

    Wu, Sujuan

    2017-05-02

    Photoinduced oxygen vacancies (OVs) are widely investigated as a vital point defect in wide-band-gap semiconductors. Still, the formation mechanism of OVs remains unclear in various materials. To elucidate the formation mechanism of photoinduced OVs in bismuth oxychloride (BiOCl), we synthesized two surface hydroxyl discrete samples in light of the discovery of the significant variance of hydroxyl groups before and after UV light exposure. It is noted that OVs can be obtained easily after UV light irradiation in the sample with surface hydroxyl groups, while variable changes were observed in samples without surface hydroxyls. Density functional theory (DFT) calculations reveal that the binding energy of Bi-O is drastically influenced by surficial hydroxyl groups, which is intensely correlated to the formation of photoinduced OVs. Moreover, DFT calculations reveal that the adsorbed water molecules are energetically favored to dissociate into separate hydroxyl groups at the OV sites via proton transfer to a neighboring bridging oxygen atom, forming two bridging hydroxyl groups per initial oxygen vacancy. This result is consistent with the experimental observation that the disappearance of photoinduced OVs and the recovery of hydroxyl groups on the surface of BiOCl after exposed to a H2O(g)-rich atmosphere, and finally enables the regeneration of BiOCl photocatalyst. Here, we introduce new insights that the evolution of photoinduced OVs is dependent on surface hydroxyl groups, which will lead to the regeneration of active sites in semiconductors. This work is useful for controllable designs of defective semiconductors for applications in photocatalysis and photovoltaics.

  10. 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

  11. Curable liquid hydrocarbon prepolymers containing hydroxyl groups and process for producing same

    Science.gov (United States)

    Rhein, R. A.; Ingham, J. D. (Inventor)

    1978-01-01

    Production of hydroxyl containing curable liquid hydrocarbon prepolymers by ozonizing a high molecular weight saturated hydrocarbon polymer such as polyisobutylene or ethylene propylene rubber is discussed. The ozonized material is reduced using reducing agents, preferably diisobutyl aluminum hydride, to form the hydroxyl containing liquid prepolymers having a substantially lower molecular weight than the parent polymer. The resulting curable liquid hydroxyl containing prepolymers can be poured into a mold and readily cured, with reactants such as toluene diisocyanate, to produce highly stable elastomers having a variety of uses such as binders for solid propellants.

  12. Hydroxylation of steroids with 11 alpha-hydroxylase of Rhizopus nigricans.

    Science.gov (United States)

    Zakelj-Mavric, M; Belic, I

    1987-08-01

    Three groups of 3-keto-4-ene steroids with different side chains were used as substrates for the induced 11 alpha-hydroxylase of Rhizopus nigricans. The highest total bioconversion as well as the highest yield of 11 alpha-hydroxylated product is found using progesterone as substrate. By changing the polarity of the side chain, much higher yields of 6 beta- and 7 beta-hydroxylated products relative to 11 alpha-hydroxylated product are obtained. Our results thus provide evidence for the importance of the side chain in steroid-enzyme interactions.

  13. Hydroxyl in garnets from Garnet Ridge, northern Arizona

    Science.gov (United States)

    Ogasawara, Y.; Sakamaki, K.; Koga, I.

    2012-12-01

    Various kinds of garnets and garnet-bearing rocks occur in Garnet Ridge, northern Arizona. These garnets have diverse origins such as mantle peridotite, subducted oceanic slab and crustal level metasomatic products (Koga & Ogasawara, 2012, AGU Fall Meeting Abstract). A typical garnet from Garnet Ridge, called "Navajo Ruby" is Cr-bearing pyrope-rich garnet that could be of the mantle peridotite origin, and another interesting garnet occurs in eclogite xenoliths of subducted slab origin, probably of Farallon plate origin (Usui et al., 2003). To understand the water behavior underneath the Colorado Plateau, we measured micro FT-IR spectra for several kinds of garnets from Garnet Ridge. The samples for micro FT-IR analyses are thick sections (50 - 500 micrometer in thickness). The size of analyzed areas is 50 x 50 μm square. We detected significant amounts of OH in "Navajo Ruby" garnets and in other types of garnets; however, OH in the garnet in eclogite xenolith was negligible or below detection limit. The peridotitic garnets (up to 2 cm across) look purplish to red brownish and are rich in pyrope component (up to 78 mol%) with significant amounts of Cr2O3 (up to 5.9 wt%) without chemical zonation. The inclusions of olivine, clinopyroxene, orthopyroxene and apatite were confirmed by laser Raman spectroscopy. The representative FT-IR absorption spectra of this type garnet are: 1) grain A (Pyp52 Alm29 Sps1 Grs14 And2 Uv2) shows two very strong IR absorption bands by OH centered at 3575 and 3660 cm-1, 2) grain B (Pyp63 Alm14 Sps0 Grs12 And1 Uv10) shows a very strong IR absorption at 3575 cm-1, and 3) grain C (Pyp62 Alm20 Sps1 Grs12 And0 Uv5) did not show IR absorption by OH. No heterogeneity of IR absorption by OH was detected in a single grain. The garnets in eclogite xenolith show clear prograde chemical zonation; core (Pyp6 Alm54 Sps1 Grs34 And5 Uv0) to rim (Pyp21 Alm64 Sps2 Grs15 And1 Uv0). The well developed rim of this garnet has no IR absorption band by OH

  14. Bioluminescence inhibition assay for the detection of hydroxylated polychlorinated biphenyls.

    Science.gov (United States)

    Teasley Hamorsky, Krystal; Ensor, C Mark; Dikici, Emre; Pasini, Patrizia; Bachas, Leonidas; Daunert, Sylvia

    2012-09-18

    Hydroxylated polychlorinated biphenyls (OH-PCBs) are an important class of contaminants that mainly originate from polychlorinated biphenyl metabolism. They may conceivably be as dangerous and persistent as the parent compounds; most prominently, OH-PCBs are endocrine disruptors. Due to increasing evidence of the presence of OH-PCBs in the environment and in living organisms, including humans, and of their toxicity, methods of detection for OH-PCBs are needed in the environmental and medical fields. Herein, we describe the development and optimization of a protein-based inhibition assay for the quantification of OH-PCBs. Specifically, the photoprotein aequorin was utilized for the detection of OH-PCBs. We hypothesized that OH-PCBs interact with aequorin, and we established that OH-PCBs actually inhibit the bioluminescence of aequorin in a dose-dependent manner. We took advantage of this phenomenon to develop an assay that is capable of detecting a wide variety of OH-PCBs with a range of detection limits, the best detection limit being 11 nM for the compound 2-hydroxy-2',3,4',5',6-pentachorobiphenyl. The viability of this system for the screening of OH-PCBs in spiked biological and environmental samples was also established. We envision the implementation of this novel bioluminescence inhibition assay as a rapid, sensitive, and cost-effective method for monitoring OH-PCBs. Furthermore, to the best of our knowledge, this is the first time aequorin has been employed to detect an analyte by the inhibition of its bioluminescence reaction. Hence, this strategy may prove to be a general approach for the development of a new generation of protein-based inhibition assays.

  15. CYP2E1 hydroxylation of aniline involves negative cooperativity.

    Science.gov (United States)

    Hartman, Jessica H; Knott, Katie; Miller, Grover P

    2014-02-01

    CYP2E1 plays a role in the metabolic activation and elimination of aniline, yet there are conflicting reports on its mechanism of action, and hence relevance, in aniline metabolism. Based on our work with similar compounds, we hypothesized that aniline binds two CYP2E1 sites during metabolism resulting in cooperative reaction kinetics and tested this hypothesis through rigorous in vitro studies. The kinetic profile for recombinant CYP2E1 demonstrated significant negative cooperativity based on a fit of data to the Hill equation (n=0.56). Mechanistically, the data were best explained through a two-binding site cooperative model in which aniline binds with high affinity (K(s)=30 μM) followed by a second weaker binding event (K(ss)=1100 uM) resulting in a threefold increase in the oxidation rate. Binding sites for aniline were confirmed by inhibition studies with 4-methylpyrazole. Inhibitor phenotyping experiments with human liver microsomes validated the central role for CYP2E1 in aniline hydroxylation and indicated minor roles for CYP2A6 and CYP2C9. Importantly, inhibition of minor metabolic pathways resulted in a kinetic profile for microsomal CYP2E1 that replicated the preferred mechanism and parameters observed with the recombinant enzyme. Scaled modeling of in vitro CYP2E1 metabolism of aniline to in vivo clearance, especially at low aniline levels, led to significant deviations from the traditional model based on non-cooperative, Michaelis-Menten kinetics. These findings provide a critical mechanistic perspective on the potential importance of CYP2E1 in the metabolic activation and elimination of aniline as well as the first experimental evidence of a negatively cooperative metabolic reaction catalyzed by CYP2E1. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Hydroxyl temperature and intensity measurements during noctilucent cloud displays

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    M. J. Taylor

    Full Text Available Two Fourier transform spectrometers have been used to investigate the properties of the near-infrared hydroxyl (OH nightglow emission under high-latitude summertime conditions and any association with noctilucent clouds (NLCs. The measurements were made from Poker Flat Research Range, Alaska (65.1°N, 147.5°W, during August 1986. Simultaneous photographic observations of the northern twilight sky were made from Gulkana, Alaska (62.2°N, 145.5°W, approximately 340 km to the south to establish the presence of NLCs over the spectrometer site. Data exhibiting significant short-term variations in the relative intensity (as much as 50–100% and rotational temperature (typically 5–15 K were recorded on six occasions when NLCs were observed. Joint measurements were also obtained on several "cloud-free" nights. No obvious relationship was found linking the mean OH intensity or its variation with the occurrence of NLCs. However, a clear tendency was found for the mean OH temperature to be lower on NLC nights than on cloud-free nights. In particular, a significant fraction of the OH(3–1 band spectra recorded by each instrument (16–57% exhibited temperatures below ~154 K on NLC nights compared with <3% on cloud-free nights. This result is qualitatively consistent with current models for ice particle nucleation and growth, but the mean OH temperature on NLC nights (~156 K was significantly higher than would be expected for long-term particle growth in this region. These observations raise questions concerning the expected proximity of the high-latitude, summertime OH layer and the NLC growth region.

  17. A helium-based model for the effects of radiation damage annealing on helium diffusion kinetics in apatite

    Science.gov (United States)

    Willett, Chelsea D.; Fox, Matthew; Shuster, David L.

    2017-11-01

    Widely used to study surface processes and the development of topography through geologic time, (U-Th)/He thermochronometry in apatite depends on a quantitative description of the kinetics of 4He diffusion across a range of temperatures, timescales, and geologic scenarios. Empirical observations demonstrate that He diffusivity in apatite is not solely a function of temperature, but also depends on damage to the crystal structure from radioactive decay processes. Commonly-used models accounting for the influence of thermal annealing of radiation damage on He diffusivity assume the net effects evolve in proportion to the rate of fission track annealing, although the majority of radiation damage results from α-recoil. While existing models adequately quantify the net effects of damage annealing in many geologic scenarios, experimental work suggests different annealing rates for the two damage types. Here, we introduce an alpha-damage annealing model (ADAM) that is independent of fission track annealing kinetics, and directly quantifies the influence of thermal annealing on He diffusivity in apatite. We present an empirical fit to diffusion kinetics data and incorporate this fit into a model that tracks the competing effects of radiation damage accumulation and annealing on He diffusivity in apatite through geologic time. Using time-temperature paths to illustrate differences between models, we highlight the influence of damage annealing on data interpretation. In certain, but not all, geologic scenarios, the interpretation of low-temperature thermochronometric data can be strongly influenced by which model of radiation damage annealing is assumed. In particular, geologic scenarios involving 1-2 km of sedimentary burial are especially sensitive to the assumed rate of annealing and its influence on He diffusivity. In cases such as basement rocks in Grand Canyon and the Canadian Shield, (U-Th)/He ages predicted from the ADAM can differ by hundreds of Ma from those

  18. Effect of Mn-Zn ferrite on apatite-wollastonite glass-ceramic (A-W GC).

    Science.gov (United States)

    Da Li, Guang; Zhou, Da Li; Pan, Tao Hua; Chen, Guo Sheng; Lin, Yun; Mao, Mao; Yan, Guo

    2009-08-01

    Magnetic bioactive glass-ceramics (M GC) were prepared by doping apatite-wollastonite glass-ceramic (A-W GC) with Mn-Zn ferrite. The effect of different contents of Mn-Zn ferrite on the phase structure, magnetic property and bioactivity of A-W GC was investigated. X-ray powder diffraction results showed that A-W GC exhibited apatite, fluorapatite and wollastonite as the main phases. The doping of Mn-Zn ferrite caused the formation of a new phase Zn(0.75)Mn(0.75)Fe(1.5)O(4) in M GC. The amount of this new phase increased with increasing content of Mn-Zn ferrite. Under a magnetic field of 7.96 x 10(5) A m(-1), the saturation magnetization of M GC increased from 4.63 to 9.7 A m(2) kg(-1), but the coercive forces of M GC decreased from 2.39 x 10(4) to 7.56 x 10(3) A m(-1) as the Mn-Zn ferrite content increased from 5% to 20% in the material. The bioactivity of samples was evaluated by soaking in simulated body fluid (SBF). The results showed that the doping of Mn-Zn ferrite decreased the bioactivity of A-W GC dramatically. It took 7 days for an apatite layer to form on the surface of A-W GC, while at least 30 days was needed for an apatite layer forming on the surface of M GC.

  19. Multiple Stage Ore Formation in the Chadormalu Iron Deposit, Bafq Metallogenic Province, Central Iran: Evidence from BSE Imaging and Apatite EPMA and LA-ICP-MS U-Pb Geochronology

    Directory of Open Access Journals (Sweden)

    Hassan Heidarian

    2018-02-01

    Full Text Available The Chadormalu magnetite-apatite deposit in Bafq metallogenic province, Central Iran, is hosted in the late Precambrian-lower Cambrian volcano-sedimentary rocks with sodic, calcic, and potassic alterations characteristic of iron oxide copper-gold (IOCG and iron oxide-apatite (IOA ore systems. Apatite occurs as scattered irregular veinlets and disseminated grains, respectively, within and in the marginal parts of the main ore-body, as well as apatite-magnetite veins in altered wall rocks. Textural evidence (SEM-BSE images of these apatites shows primary bright, and secondary dark areas with inclusions of monazite/xenotime. The primary, monazite-free fluorapatite contains higher concentrations of Na, Si, S, and light rare earth elements (LREE. The apatite was altered by hydrothermal events that led to leaching of Na, Si, and REE + Y, and development of the dark apatite. The bright apatite yielded two U-Pb age populations, an older dominant age of 490 ± 21 Ma, similar to other iron deposits in the Bafq district and associated intrusions, and a younger age of 246 ± 17 Ma. The dark apatite yielded a U-Pb age of 437 ± 12 Ma. Our data suggest that hydrothermal magmatic fluids contributed to formation of the primary fluorapatite, and sodic and calcic alterations. The primary apatite reequilibrated with basinal brines in at least two regional extensions and basin developments in Silurian and Triassic in Central Iran.

  20. Effect of metallographic structure and machining process on the apatite-forming ability of sodium hydroxide- and heat-treated titanium.

    Science.gov (United States)

    Miyazaki, Toshiki; Sasaki, Takashi; Shirosaki, Yuki; Yokoyama, Ken'ichi; Kawashita, Masakazu

    2018-01-01

    Although titanium (Ti) is clinically used for hard tissue reconstruction, it has low bone-bonding ability, i.e. bioactivity. Materials able to deposit apatite on their surfaces within the body is considered to exhibit bioactivity. Effects of the metallographic structure and machining process of Ti on its apatite-forming ability remains unclear. In this study, Ti substrates subjected to various preheating and machining processes were then subjected to NaOH and heat treatments. The apatite-forming abilities of resulting Ti were examined in simulated body fluid (SBF). Preheating of the Ti decreased its reactivity with NaOH solution. When quenched or annealed Ti was subjected to NaOH and heat treatments, the induction period for apatite formation in SBF slightly increased. This was attributed to a decrease in sodium titanate and increase in rutile on the Ti surface after the treatments. Substrates subjected to wire-electrical-discharge machining did not form apatite. This was attributed to the inhibition of PO43- adsorption on their surfaces following Ca2+ adsorption, which is an essential process for apatite nucleation. Contamination of Ti surface by components of the brass wire used in the machining contributed to the inhibition. The bioactivity of surface-modified Ti was therefore significantly affected by its thermal treatment and machining process.

  1. Morphological and chemical evaluation of bone with apatite-coated Al2O3 implants as scaffolds for bone repair

    Directory of Open Access Journals (Sweden)

    A. L. M. Maia F.

    2013-12-01

    Full Text Available The clinical challenge in the reconstruction of bone defects has stimulated several studies in search of alternatives to repair these defects. The ceramics are considered as synthetic scaffolds and are used in dentistry and orthopedics. This study aimed to evaluate by micro energy-dispersive X-ray fluorescence spectrometry (µ-EDXRF and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS, the influence of uncoated and apatite-coated Al2O3 implants on bone regeneration. Twelve samples of Al2O3 implants were prepared and half of this samples (n = 6 were apatite-coated by the modified biomimetic method and then the ceramic material were implanted in the tibia of rabbits. Three experimental groups were tested: Group C - control, surgery procedure without ceramic implant, Group Ce - uncoated Al2O3 implants (n = 6 and Group CeHA - apatite-coated Al2O3 implants (n = 6. The deposition of bone tissue was determined by measuring the weight content of Ca and P through surface mapping of bone-implant interface by µ-EDXRF and through point analysis by EDS. It was observed after thirty days of treatment a greater deposition of Ca and P in the group treated with CeHA (p <0.001 compared to group C. The results suggest that ceramic coated with hydroxyapatite (CeHA can be an auxiliary to bone deposition in tibia defect model in rabbits.

  2. 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.

  3. Application of MINTEQA2 to the evaluation of apatite as a precipitant for acid mine drainage treatment

    Energy Technology Data Exchange (ETDEWEB)

    Choi, J.C.; West, T.R.; Seol, Y. [Purdue University, West Lafayette, IN (United States). Dept. of Earth and Atmospheric Sciences

    1997-12-31

    The apatite drain system is a new method for acid mine drainage (AMD) treatment. Laboratory tests and field experiments showed that this technique can remove high concentrations of iron and aluminium in AMD having a pH below 4.0 In addition, this system removes both ferric and ferrous iron, whereas a constructed wetlands system removes only ferric iron when converted from the ferrous state in the wetland. A geochemical model, MINTEQA2, was used to simulate the changes in concentration of aqueous constituents, and in the pH and the potential mineral phase. Results of MINTEQA2 support the conclusions of the laboratory and field experiments. Apatite is effective in removing iron, sulfate, and aluminium from AMD; pH was inversely proportional to the flow rate until the equilibrium point was reached (pH = 4.09 at 25{degree}C). Also, the role of apatite as a precipitant and pH buffer was limited by its solubility.

  4. Synthesis and characterisation of new Bi(iii)-containing apatite-type oxide ion conductors: the influence of lone pairs.

    Science.gov (United States)

    Tate, M L; Fuller, C A; Avdeev, M; Brand, H E A; McIntyre, G J; Radosavljevic Evans, I

    2017-09-26

    Lone-pair cations are known to enhance oxide ion conductivity in fluorite- and Aurivillius-type materials. Among the apatite-type phases, the opposite trend is found for the more widely studied silicate oxide ion conductors, which exhibit a dramatic decrease in conductivity on Bi(iii) incorporation. In this work, the influence of lone-pair cations on the properties of apatite-type germanate oxide ion conductors has been investigated by preparing and characterising seven related compositions with varying Bi(iii) content, by X-ray and neutron powder diffraction and impedance spectroscopy. All materials are very good oxide ion conductors (with conductivities of up to 1.29 × 10-2 S cm-1 at 775 °C). Increasing Bi(iii) content leads to increases in conductivity by up to an order of magnitude, suggesting significant differences in the oxide-ion conduction mechanisms between lone-pair-containing apatite-type germanate and silicate solid electrolytes.

  5. Quinone-rich polydopamine functionalization of yttria stabilized zirconia for apatite biomineralization: The effects of coating temperature

    Science.gov (United States)

    Zain, Norhidayu Muhamad; Hussain, Rafaqat; Abdul Kadir, Mohammed Rafiq

    2015-08-01

    The use of yttria stabilized zirconia (YSZ) as biomedical implants is often offset by its bioinert nature that prevents its osseointegration to occur. Therefore, the functionalization of YSZ surface by polydopamine to facilitate the biomineralization of apatite layer on top of the coated film has incessantly been studied. In this study YSZ discs were first immersed in 2 mg/mL of stirred dopamine solution at coating temperatures between 25 and 80 °C. The specimens were then incubated for 7d in 1.5 SBF. The effect of coating temperature on the properties (chemical compositions and wettability) and the apatite mineralization on top of the generated films was investigated. It was found that at 50 °C, the specimen displayed the highest intensity of Ca 2p peak (1.55 ± 0.42 cps) with Ca/P ratio of 1.67 due to the presence of abundant quinone groups (Cdbnd O). However, the hydrophilicity (40.9 ± 01.7°) was greatly improved at 60 °C accompanied by the highest film thickness of 306 nm. Therefore, it was concluded that the presence of high intensity of quinone groups (Cdbnd O) in polydopamine film at elevated temperature affects the chelation of Ca2+ ions and thus enhance the growth of apatite layer on top of the functionalized YSZ surface.

  6. Development of an electrospun nano-apatite/PCL composite membrane for GTR/GBR application.

    Science.gov (United States)

    Yang, Fang; Both, Sanne K; Yang, Xuechao; Walboomers, X Frank; Jansen, John A

    2009-11-01

    In dental practice, membranes are used as a barrier to prevent soft tissue ingrowth and create space for slowly regenerating periodontal and bony tissues. The aim of this study was to develop a biodegradable membrane system which can be used for guided tissue or bone regeneration. Three types of composite fibrous membranes based on nano-apatite (nAp) and poly(epsilon-caprolactone) (PCL) were made by electrospinning, i.e. n0 (nAp:PCL=0:100), n25 (nAp:PCL=25:100) and n50 (nAp:PCL=50:100) with average fiber diameters ranging from 320 to 430 nm. Their structural, mechanical, chemical and biological properties were evaluated. Tensile test revealed that n25 had the highest strength and toughness, indicating there is an optimal ratio of nAp to polymer for mechanical reinforcement. Subsequently, a simulated body fluid immersion test confirmed that the presence of nAp enhanced the bioactive behavior of the membranes. Finally, an in vitro osteoblast cell study showed that all membranes supported proliferation, but the presence of nAp facilitated an early cell differentiation. This study demonstrated that an electrospun membrane incorporating nAp is strong, enhances bioactivity and supports osteoblast-like cell proliferation and differentiation. The membrane system can be used as a prototype for the further development of an optimal membrane for clinical use.

  7. Mesoporous silica/apatite nanocomposite: special synthesis route to control local drug delivery.

    Science.gov (United States)

    Sousa, A; Souza, K C; Sousa, E M B

    2008-05-01

    Synthetic hydroxyapatite is widely used in medicine and dentistry due its notable biocompatibility and bioactivity properties. The hydroxyapatite incorporation into silica has demonstrated excellent bioactivity or biodegradability, according to the content of calcium ions. Procedures to obtain ordered mesoporous silicates rely on the micelle-forming properties of a surfactant, whose chemical composition, size and concentration control the structural dimensions of the final material. This paper reports the synthesis of two types mesoporous materials: pure MCM-41 and a nanocomposite of apatite and mesoporous silica, MCM-41-HA. The samples were charged with atenolol as a model drug and in vitro release essays were carried out. The bioactivity behavior was investigated as a function of soaking time in simulated body fluid. The materials were characterized by X-ray diffraction, N2 adsorption, FTIR spectroscopy, scanning electron microscopy, dispersive energies spectroscopy, and transmission electron microscopy. The influence of the release rate of atenolol molecules from pure MCM-41 mesoporous and containing hydroxyapatite was demonstrated, since it results in a very slowly drug delivery from the nanocomposite system.

  8. Local structure and oxide-ion conduction mechanism in apatite-type lanthanum silicates.

    Science.gov (United States)

    Masson, Olivier; Berghout, Abid; Béchade, Emilie; Jouin, Jenny; Thomas, Philippe; Asaka, Toru; Fukuda, Koichiro

    2017-01-01

    The local structure of apatite-type lanthanum silicates of general formula La9.33+x(SiO4)6O2+3x/2 has been investigated by combining the atomic pair distribution function (PDF) method, conventional X-ray and neutron powder diffraction (NPD) data and density functional theory (DFT) calculations. DFT was used to build structure models with stable positions of excess oxide ions within the conduction channel. Two stable interstitial positions were obtained in accordance with literature, the first one located at the very periphery of the conduction channel, neighbouring the SiO4 tetrahedral units, and the second one closer to the channel axis. The corresponding PDFs and average structures were then calculated and tested against experimental PDFs obtained by X-ray total scattering and NPD Rietveld refinements results gathered from literature. It was shown that of the two stable interstitial positions obtained with DFT only the second one located within the channel is consistent with experimental data. This result consolidates one of the two main conduction mechanisms along the c-axis reported in the literature, namely the one involving cooperative movement of O4 and Oi ions.

  9. 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.

  10. Biomimetic formation of apatite on the surface of porous gelatin/bioactive glass nanocomposite scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Mozafari, Masoud, E-mail: mmozafari@aut.ac.ir [Biomaterials Group, Faculty of Biomedical Engineering (Center of Excellence), Amirkabir University of Technology, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Rabiee, Mohammad; Azami, Mahmoud; Maleknia, Saied [Biomaterials Group, Faculty of Biomedical Engineering (Center of Excellence), Amirkabir University of Technology, PO Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2010-12-15

    There have been several attempts to combine bioactive glasses (BaGs) with biodegradable polymers to create a scaffold material with excellent biocompatibility, bioactivity, biodegradability and toughness. In the present study, the nanocomposite scaffolds with compositions based on gelatin (Gel) and BaG nanoparticles in the ternary SiO{sub 2}-CaO-P{sub 2}O{sub 5} system were prepared. In vitro evaluations of the nanocomposite scaffolds were performed, and for investigating their bioactive capacity these scaffolds were soaked in a simulated body fluid (SBF) at different time intervals. The scaffolds showed significant enhancement in bioactivity within few days of immersion in SBF solution. The apatite formation at the surface of the nanocomposite samples confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD) analyses. In vitro experiments with osteoblast cells indicated an appropriate penetration of the cells into the scaffold's pores, and also the continuous increase in cell aggregation on the bioactive scaffolds with increase in the incubation time demonstrated the ability of the scaffolds to support cell growth. The SEM observations revealed that the prepared scaffolds were porous with three dimensional (3D) and interconnected microstructure, pore size was 200-500 {mu}m and the porosity was 72-86%. The nanocomposite scaffold made from Gel and BaG nanoparticles could be considered as a highly bioactive and potential bone tissue engineering implant.

  11. 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

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

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    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.

  13. Improved Bonding of Partially Osteomyelitic Bone to Titanium Pins Owing to Biomimetic Coating of Apatite

    Directory of Open Access Journals (Sweden)

    Hirotaka Mutsuzaki

    2013-12-01

    Full Text Available Increased fixation strength of the bone-pin interface is important for inhibiting pin loosening after external fixation. In a previous study, an apatite (Ap layer was formed on anodically oxidized titanium (Ti pins by immersing them in an infusion fluid-based supersaturated calcium phosphate solution at 37 °C for 48 h. In the present study, an Ap layer was also successfully formed using a one-step method at 25 °C for 48 h in an infusion fluid-based supersaturated calcium phosphate solution, which is clinically useful due to the immersion temperature. After percutaneous implantation in a proximal tibial metaphysis for four weeks in rabbits (n = 20, the Ti pin coated with the Ap layer showed significantly increased extraction torque compared with that of an uncoated Ti screw even with partial osteomyelitis present, owing to dense bone formation on the Ap layer in the cortical and medullary cavity regions. When the infection status was changed from “no osteomyelitis” to “partial osteomyelitis,” the extraction torque in the Ap group with “partial osteomyelitis” was almost identical to that for “no osteomyelitis” cases. These results suggest that the Ap layer formed by the room temperature process could effectively improve the fixation strength of the Ti pin for external fixation clinically even with partial osteomyelitis present.

  14. 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. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Intense turquoise colors of apatite-type compounds with Mn5+ in tetrahedral coordination

    Science.gov (United States)

    Medina, Elena A.; Li, Jun; Stalick, Judith K.; Subramanian, M. A.

    2016-02-01

    The solid solutions of chlorapatite compounds Ba5Mn3-xVxO12Cl (x = 0-3.0) and Ba5Mn3-xPxO12Cl (x = 0-3.0) have been synthesized through solid state reactions and Pechini or sol-gel method using citric acid. The colors of the samples change from white (x = 3.0) through turquoise (x = 1.5) to dark green (x = 0) with increasing amount of manganese. Optical measurements reveal that the origin of the color is presumably a combination of d-d transitions of Mn5+ and cation-anion charge transfer from transition metals to oxygens. Near IR reflectance measurements indicate that synthesized compounds are promising materials for ;cool pigments; applications. Magnetic measurements verify that manganese has two unpaired electrons and exhibits 5 + oxidation state. The IR spectra change systematically with sample compositions and the fingerprint region (700 cm-1 to 1100 cm-1) indicates characteristic bands belonging to (MnO4)3-, (VO4)3- and (PO4)3- functional groups. Structure refinements using neutron data confirm that Mn5+, V5+ and P5+ cations occupy the tetrahedral sites in the apatite structure.

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

    Science.gov (United States)

    Piccirillo, C; Silva, M F; Pullar, R C; Braga da Cruz, I; Jorge, R; Pintado, M M E; Castro, P M L

    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 °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. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. The dependence of thermoluminescence sensitivity upon the temperature of irradiation in meteorites and in terrestrial apatites

    Energy Technology Data Exchange (ETDEWEB)

    Durrani, S.A.; Al-Khalifa, I.J.M. (Birmingham Univ. (UK). School of Physics and Space Research)

    1990-01-01

    Measurements are reported on the TL sensitivity (i.e. TL glow output per unit {gamma} ray test dose) of meteoritic specimens as well as terrestrial fluor- and chlor-apatites, as a function of irradiation temperature (T{sub irr}). The irradiation temperatures ranged from liquid nitrogen to room temperature (77 - 293 K). A kilocurie {sup 60}Co {gamma} ray source was used to deliver test doses of 400 Gy (40 krad) and 40 (4 krad) to the various samples. A strong dependence of the TL sensitivity upon the temperature of irradiation was noted in the case of Kirin meteorite: its TL sensitivity (for the 493 K readout peak) decreased by a factor of {similar to} 2 when T{sub irr} rose from liquid nitrogen (77 K) to dry ice in acetone (197 K) temperature, in the case of both 400 Gy and 40 Gy {gamma} ray doses. In the case of the Antarctic meteorite specimen (ALHA 77182.13), there was a smaller effect, viz. a fall of {similar to} 14% in the TL output corresponding to dry ice and higher irradiating temperatures as compared to the 77 K irradiation. For chlorapatite, the TL sensitivity decreased monotonically with increasing temperature for both the 563 K and the 448 K glow peaks. For the fluorapatite, the effect of reduced response was observed only between -17{sup 0}C (256 K) and room temperature (293 K). Both the theoretical and the practical implications of these observations are discussed. (author).

  18. 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

  19. Oxygen isotopes from biogenic apatites suggest widespread endothermy in Cretaceous dinosaurs

    Science.gov (United States)

    Amiot, Romain; Lécuyer, Christophe; Buffetaut, Eric; Escarguel, Gilles; Fluteau, Frédéric; Martineau, François

    2006-06-01

    The much debated question of dinosaur thermophysiology has not yet been conclusively solved despite numerous attempts. We used the temperature-dependent oxygen isotope fractionation between vertebrate body water (δ 18O body water) and phosphatic tissues (δ 18O p) to compare the thermophysiology of dinosaurs with that of non-dinosaurian ectothermic reptiles. Present-day δ 18O p values of vertebrate apatites show that ectotherms have higher δ 18O p values than endotherms at high latitudes due to their lower body temperature, and conversely lower δ 18O p values than endotherms at low latitudes. Using a data set of 80 new and 49 published δ 18O p values, we observed similar and systematic differences in δ 18O p values (Δ 18O) between four groups of Cretaceous dinosaurs (theropods, sauropods, ornithopods and ceratopsians) and associated fresh water crocodiles and turtles. Expressed in terms of body temperatures ( Tb), these Δ 18O values indicate that dinosaurs maintained rather constant Tb in the range of endotherms whatever ambient temperatures were. This implies that high metabolic rates were widespread among Cretaceous dinosaurs belonging to widely different taxonomic groups and suggest that endothermy may be a synapomorphy of dinosaurs, or may have been acquired convergently in the studied taxa.

  20. Hydroxylated polymethoxyflavones and methylated flavonoids in sweet orange (Citrus sinensis) peel.

    Science.gov (United States)

    Li, Shiming; Lo, Chih-Yu; Ho, Chi-Tang

    2006-06-14

    Polymethoxyflavones (PMFs) from citrus genus have been of particular interest because of their broad spectrum of biological activities, including antiinflammatory, anticarcinogenic, and antiatherogenic properties. There have been increasing interests in the exploration of health beneficial properties of PMFs in citrus fruits. Therefore, the isolation and characterization of PMFs from sweet orange (Citrus sinensis) peel will lead to new applications of the byproducts from orange juice processes and other orange consumption in nutraceutical and pharmaceutical products. In our study, eight hydroxylated PMFs, six PMFs, one polymethoxyflavanone, one hydroxylated polymethoxyflavanone, and two hydroxylated polymethoxychalcones were isolated from sweet orange peel and their structures were elucidated by various MS, UV, and different NMR techniques. Some of the hydroxylated PMFs and chalcones are newly isolated from sweet orange peel.

  1. MLS/Aura L2 Hydroxyl (OH) Mixing Ratio V002

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2OH is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydroxyl derived from radiances measured by the THz radiometer. The current version is 2.2....

  2. MLS/Aura Level 2 Hydroxyl (OH) Mixing Ratio V004

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2OH is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydroxyl derived from radiances measured by the THz radiometer. The current version is 4.2....

  3. Scattering of state-selected and oriented hydroxyl radicals by halogen hydrides and xenon

    NARCIS (Netherlands)

    Moise, Angelica Valentina

    2007-01-01

    The interaction of the OH radical with atoms and other molecules is relevant for many physical and chemical processes involved in atmospheric, combustion and interstellar chemistry. Various experimental and theoretical studies have revealed information concerning the interaction of the hydroxyl

  4. Stratospheric ozone and hydroxyl radical measurements by balloon-borne lidar

    Science.gov (United States)

    Heaps, W. S.; Mcgee, T. J.; Hudson, R. D.; Caudill, L. O.

    1982-01-01

    An experiment is reported in which a balloon-borne lidar system was used to measure ozone and the hydroxyl radical in the stratosphere by two lidar techniques. Ozone was measured in the 20-37 km altitude range using differential absorption lidar, and the hydroxyl radical was measured in the 34-37 km range using remote laser-induced fluorescence. Ozone concentrations were determined with a vertical resolution of 0.5 km, and in addition, horizontally resolved ozone measurements with 0.15-km resolution were obtained over a 2-km range. The temporal variation of the hydroxyl radical concentration ranged from 40 parts/trillion shortly after noon to about 5 parts/trillion two hours after sunset. Possible modifications to the system are discussed which can yield an improvement in the sensitivity of between one and two orders of magnitude, thus permitting measurements of the hydroxyl radical in the 20-30-km altitude range.

  5. Atmospheric hydroxyl radical production from electronically excited NO2 and H2O.

    Science.gov (United States)

    Li, Shuping; Matthews, Jamie; Sinha, Amitabha

    2008-03-21

    Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(1D) + H2O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation.

  6. Hydroxylation of benzene to phenol over magnetic recyclable nanostructured CuFe mixed-oxide catalyst

    CSIR Research Space (South Africa)

    Makgwane, PR

    2015-03-01

    Full Text Available A highly active and magnetically recyclable nanostructured copper–iron oxide (CuFe) catalyst has been synthesized for hydroxylation of benzene to phenol under mild reaction conditions. The obtained catalytic results were correlated with the catalyst...

  7. MLS/Aura L2 Hydroxyl (OH) Mixing Ratio V003

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2OH is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydroxyl derived from radiances measured by the THz radiometer. The current version is...

  8. Rate constants of reactions of {kappa}-carrageenan with hydrated electron and hydroxyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Abad, L.V. [Nuclear Professional School, School of Engineering Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Philippine Nuclear Research Institute, Commonwealth Avenue, Diliman, Quezon City (Philippines)], E-mail: lvabad@pnri.dost.gov.ph; Saiki, S.; Kudo, H.; Muroya, Y.; Katsumura, Y. [Nuclear Professional School, School of Engineering Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Rosa, A.M. de la [Philippine Nuclear Research Institute, Commonwealth Avenue, Diliman, Quezon City (Philippines)

    2007-12-15

    The rate constants for the reactions of {kappa}-carrageenan with hydrated electron and hydroxyl radical was investigated by pulse radiolysis and laser photolysis. The kinetics of the reaction of hydrated electron indicates no seeming reaction with {kappa}-carrageenan. On the other hand, hydroxyl radical reacts very rapidly with {kappa}-carrageenan at a rate constant of approximately 1.2 x 10{sup 9} M{sup -1} s{sup -1}. This rate constant varies with pH.

  9. Presence of hydrogen peroxide, a source of hydroxyl radicals, in acid electrolyzed water.

    Directory of Open Access Journals (Sweden)

    Takayuki Mokudai

    Full Text Available BACKGROUND: Acid electrolyzed water (AEW, which is produced through the electrolysis of dilute sodium chloride (NaCl or potassium chloride solution, is used as a disinfectant in various fields because of its potent antimicrobial activity. The hydroxyl radical, an oxygen radical species, is often suggested as a putative active ingredient for AEW antimicrobial activity. METHODOLOGY/PRINCIPAL FINDINGS: The aim of the present study is to detect hydroxyl radicals in AEW. The hydroxyl radicals in AEW prepared under different conditions were determined using an electron spin resonance (ESR technique. A signal from 5,5-dimethyl-1-pyrroline N-oxide (DMPO-OH, an adduct of DMPO and the hydroxyl radical, was detected in AEW prepared by double or triple electrolyses of 1% NaCl but not of 0.1% NaCl solution. Then the presence of hydrogen peroxide as a proposed source of hydroxyl radicals was examined using a combination of ESR and a Fenton reaction. The DMPO-OH signal was clearly detected, even in AEW prepared by single electrolysis of 0.1% NaCl solution, when ferrous sulfate was added to induce a Fenton reaction, indicating the presence of hydrogen peroxide in the AEW. Since sodium formate, a hydroxyl radical scavenger, did not affect the bactericidal activity of AEW, it is concluded that the radical is unlikely to contribute to the antimicrobial activity of AEW, although a small amount of the radical is produced from hydrogen peroxide. Dimethyl sulfoxide, the other hydroxyl radical scavenger used in the present study, canceled the bactericidal activity of AEW, accompanied by complete depletion of free available chlorine, suggesting that hypochlorous acid is probably a major contributor to the antimicrobial activity. CONCLUSIONS: It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, the antimicrobial activity of AEW does not depend on these radicals.

  10. In situ mechanical and molecular investigations of collagen/apatite biomimetic composites combining Raman spectroscopy and stress-strain analysis.

    Science.gov (United States)

    Chatzipanagis, Konstantinos; Baumann, Christoph G; Sandri, Monica; Sprio, Simone; Tampieri, Anna; Kröger, Roland

    2016-12-01

    We report the design, fabrication and application of a novel micro-electromechanical device coupled to a confocal Raman microscope that enables in situ molecular investigations of micro-fibers under uniaxial tensile load. This device allows for the mechanical study of micro-fibers with diameters in the range between 10 and 100μm and lengths of several hundred micrometers. By exerting forces in the mN range, the device enables an important force range to be accessed between that of atomic force microscopy and macroscopic stress-strain measurement devices. The load is varied using a stiffness-calibrated glass micro-needle driven by a piezo-translator during simultaneous Raman microscopy imaging. The method enables experiments probing the molecular response of micro-fibers to external stress. This set-up was applied to biomimetic non-mineralized and mineralized collagen micro-fibers revealing that above 30% mineralization the proline-related Raman band shows a pronounced response to stress, which is not observed in non-mineralized collagen. This molecular response coincides with a strong increase in the Young's modulus from 0.5 to 6GPa for 0% and 70% mineralized collagen, respectively. Our results are consistent with a progressive interlocking of the collagen triple-helices by apatite nanocrystals as the degree of mineralization increases. Collagen and apatite are the main constituents regulating the mechanical properties of bone. Hence, an improved understanding of the impact of mineralization on these properties is of large interest for the scientific community. This paper presents systematic studies of synthetic collagen microfibers with increasing apatite content and their response to tensile stress by using a novel self-made electromechanical device combined with a Raman spectrometer for molecular level studies. The impact of apatite on the mechanical and molecular response of collagen is evaluated giving important insights into the interaction between the

  11. Thermochemistry of Hydroxyl and Hydroperoxide Substituted Furan, Methylfuran, and Methoxyfuran.

    Science.gov (United States)

    Hudzik, Jason M; Bozzelli, Joseph W

    2017-06-15

    Reaction pathways are influenced by thermochemical properties, species stability, and chemical kinetics. Understanding these factors allows for an understanding of the reaction paths and formation of intermediate species. Enthalpies of formation (ΔHf,298(°)), entropies (S298(°)), heat capacities (Cp(T)), oxygen-hydrogen (O-H), oxygen-oxygen (O-O), and (R-O) bond dissociation energies (BDEs) are reported for hydroxyl and hydroperoxide substituted furan, methylfuran, and methoxyfuran species. Standard enthalpies of formation for parent and radical species have been determined using density functional theory B3LYP/6-31G(d,p), B3LYP/6-311G(2d,2p), and M06-2X/6-31G(d,p) along with higher-level CBS-QB3 and CBS-APNO composite methods. Isodesmic work reactions were employed to improve accuracy by canceling error and show consistency between the levels of theory. Corresponding O-H and O-O BDEs are determined and compared to other similar structures. The stability of the furan moiety coupled with the double-bond-forming capability of the oxygen moiety results in a number of bond energies significantly lower than one might have expected. Substituted hydroperoxides are calculated to have ROO-H BDEs between 86.9 and 94.2 kcal mol(-1), and their RO-OH BDEs show a large 49 kcal mol(-1) range of -2.3-46.8 kcal mol(-1). Substituted alcohols also show a wide 48 kcal mol(-1) range with RO-H BDEs, ranging from 59.3 to 106.9 kcal mol(-1). Bond lengths of parent and radical species are presented to highlight potential bonds of interest leading to furan ring opening. Group additivity is discussed, and groups for substituted furan, methylfuran, and methoxyfuran species are derived. Structures, moments of inertia, vibrational frequencies, and internal rotor potentials are calculated at the B3LYP/6-31G(d,p) density functional level and are used to determine the S298(°) and Cp(T) values.

  12. Mechanism of N-hydroxylation catalyzed by flavin-dependent monooxygenases.

    Science.gov (United States)

    Badieyan, Somayesadat; Bach, Robert D; Sobrado, Pablo

    2015-02-20

    Aspergillus fumigatus siderophore (SidA), a member of class B flavin-dependent monooxygenases, was selected as a model system to investigate the hydroxylation mechanism of heteroatom-containing molecules by this group of enzymes. SidA selectively hydroxylates ornithine to produce N(5)-hydroxyornithine. However, SidA is also able to hydroxylate lysine with lower efficiency. In this study, the hydroxylation mechanism and substrate selectivity of SidA were systematically studied using DFT calculations. The data show that the hydroxylation reaction is initiated by homolytic cleavage of the O-O bond in the C(4a)-hydroperoxyflavin intermediate, resulting in the formation of an internal hydrogen-bonded hydroxyl radical (HO(•)). As the HO(•) moves to the ornithine N(5) atom, it rotates and donates a hydrogen atom to form the C(4a)-hydroxyflavin. Oxygen atom transfer yields an aminoxide, which is subsequently converted to hydroxylamine via water-mediated proton shuttling, with the water molecule originating from dehydration of the C(4a)-hydroxyflavin. The selectivity of SidA for ornithine is predicted to be the result of the lower energy barrier for oxidation of ornithine relative to that of lysine (16 vs 24 kcal/mol, respectively), which is due to the weaker stabilizing hydrogen bond between the incipient HO(•) and O3' of the ribose ring of NADP(+) in the transition state for lysine.

  13. The hydroxyl-modified surfaces on glass support for fabrication of carbohydrate microarrays.

    Science.gov (United States)

    Nan, Gang; Yan, Hua; Yang, Ganglong; Jian, Qiang; Chen, Chao; Li, Zheng

    2009-01-01

    Glycan-protein interactions play important biological roles in biological processes. But there is a lack of simple high-throughput methods to elucidate recognition events between carbohydrates and protein. Although, there have been a number of glycan arrays developed in recent years utilizing different strategies and for different purposes, the method presented in this paper, a direct covalent immobilization of sugars to hydroxyl-modified glass surface, can be a very useful general method. Here, two strategies have been developed for the production of carbohydrate microarrays by the underivatized sugars that efficiently immobilized on hydroxyl-functionalized glass surface by formation of glycosidic bond with the hemiacetal group at the reducing end of the suitable carbohydrates via condensation. Firstly, untreated glass slides were amino- and epoxy-silanized, respectively. Then, they were further hydroxyl functionalized with different surface chemistries. The carbohydrate microarrays were fabricated on hydroxyl-functionalized glass by robotic arrayer. Additionally, experiments for the characterization of carbohydrates-protein interaction were performed to compare these strategies. Overall best results in terms of conveniency and sensitivity were obtained with hydroxyl-functionalization on epoxysilanized surfaces. The hydroxyl-functionalized slide was used to detect the amount of mannose immobilized on the glass surface. The limit of detection of the fabricated mannose microarray was 100 nM.

  14. CATALYTIC PERFORMANCES OF Fe2O3/TS-1 CATALYST IN PHENOL HYDROXYLATION REACTION

    Directory of Open Access Journals (Sweden)

    Didik Prasetyoko

    2010-07-01

    Full Text Available Hydroxylation reaction of phenol into diphenol, such as hydroquinone and catechol, has a great role in many industrial applications. Phenol hydroxylation reaction can be carried out using Titanium Silicalite-1 (TS-1 as catalyst and H2O2 as an oxidant. TS-1 catalyst shows high activity and selectivity for phenol hydroxylation reaction. However, its hydrophobic sites lead to slow H2O2 adsorption toward the active site of TS-1. Consequently, the reaction rate of phenol hydroxylation reaction is tends to be low. Addition of metal oxide Fe2O3 enhanced hydrophilicity of TS-1 catalyst. Liquid phase catalytic phenol hydroxylation using hydrogen peroxide as oxidant was carried out over iron (III oxide-modified TS-1 catalyst (Fe2O3/TS-1, that were prepared by impregnation method using iron (III nitrate as precursor and characterized by X-ray diffraction, infrared spectroscopy, nitrogen adsorption, pyridine adsorption, and hydrophilicity techniques. Catalysts 1Fe2O3/TS-1 showed maximum catalytic activity of hydroquinone product. In this research, the increase of hydroquinone formation rate is due to the higher hydrophilicity of Fe2O3/TS-1 catalysts compare to the parent catalyst, TS-1.   Keywords: Fe2O3/TS-1, hydrophilic site, phenol hydroxylation

  15. Carbonate-hosted Pb-Zn±Ag and Ba deposits in the Chañarcillo group, northern Chile : multiple fluid types and genetic processes

    OpenAIRE

    Lieben, François Claude Serge

    1999-01-01

    D'anciens gisements et indices de Pb-Zn±Ag et Ba dans le Groupe de Chañarcillo, dans le nord du Chili, témoignent de fluides hydrothermaux ayant circulé dans ces formations carbonatées et volcanoclastiques d'arrière-arc depuis le Crétacé inférieur. Une description détaillée et la paragenèse de plusieurs gisements sont présentées, et les fluides minéralisateurs sont étudiés par le biais des inclusions fluides et de la composition isotopique (Sr, S, Pb) des minéraux de gangue et d'altération. L...

  16. Simulation of land use evolution by discrete events method: Application to “la chaîne des puys” from XV to XVIII Century

    Directory of Open Access Journals (Sweden)

    Y. Michelin

    1998-01-01

    Full Text Available By using a discrete event method, simulation of land use evolution has been applied to a landscape model of “la ChaÎne des Puys” (French Massif Central during along period (XV–XVIII centuries. The indications concerning the evolution of land use are in conformity with the observation of actual situations but the dynamic changes are faster than in actual facts. In spite of limitations due to necessary simplifications, it is now established that the discrete event method is efficient to simulate land use evolution during a long period. The model is immediately able to describe actual dynamics and to show sensitive variables with their critical values. Although oversimplified, it shows how far factors such as level of crops production and taxation can influence land use and landscape changes with a more or less lengthy period. In the future, the model should be bettered by introducing other determined and/or stochastic events.

  17. Glacial and periglacial geomorphology and chronology around the Nevado de Chañi (Cordillera Oriental of Jujuy): implication for past climate in NW Argentina

    Science.gov (United States)

    Martini, M. A.; Strelin, J. A.; Kaplan, M. R.; Schaefer, J. M.

    2012-12-01

    The Nevado de Chañi (24°3' 45'' S; 65° 44' 43'' W) is one of the highest massifs in northwestern Argentina (5882 masl). It is the summit of a N-S trending mountain range located just north of the Arid Diagonal, which separates the southern Pacific westerlies from the South American Summer Monsoon domains. This range consists of Precambrian and Paleozoic sedimentary rocks intruded by Ordovician granites. It has been broadly eroded by glaciers during the Late Pleistocene but today no glaciers exist in the area due to aridity, and periglacial activity takes a main role in the development of the landscape above 4600m. The orographically-driven climate conditions, with seasonal summer wet-air masses moving from the Atlantic, determine that the west side of the massif is clearly drier and probably warmer than the east-facing side. Three main groups of moraines are recognized on both sides of Chañi. We collected moraine boulders from the different glacial landforms for 10Be surface exposure dating, which is in progress. Seven peat bogs were cored to obtain minimum-limiting radiocarbon ages of the deglaciation and limnogeologic change during the post glacial period. Ten preliminary 10Be dates reveal pre-LGM (Last Glacial Maximum) and post LGM ages for the glacier moraines on the west side of the massif. The periglacial geomorphology around Chañi is mainly represented by scree activity, giving way to solifluction and formation of protalus lobes. We focused especially on rock glacier formation. Active, inactive, and fossil rock glaciers were distinguished taking into account geomorphological characteristics such as the frontal slope and ridge and furrows preservation. The lower limit for active and inactive/fossil rock glaciers is located above ~4700m and ~4500m, respectively. Cross-cutting relations with the dated moraines will provide the maximum age of these geomorphic features. Active rock glaciers at present have predominately S and E slopes and are located bellow

  18. Diffusion Study by IR Micro-Imaging of Molecular Uptake and Release on Mesoporous Zeolites of Structure Type CHA and LTA

    Directory of Open Access Journals (Sweden)

    Jörg Kärger

    2013-07-01

    Full Text Available The presence of mesopores in the interior of microporous particles may significantly improve their transport properties. Complementing previous macroscopic transient sorption experiments and pulsed field gradient NMR self-diffusion studies with such materials, the present study is dedicated to an in-depth study of molecular uptake and release on the individual particles of mesoporous zeolitic specimens, notably with samples of the narrow-pore structure types, CHA and LTA. The investigations are focused on determining the time constants and functional dependences of uptake and release. They include a systematic variation of the architecture of the mesopores and of the guest molecules under study as well as a comparison of transient uptake with blocked and un-blocked mesopores. In addition to accelerating intracrystalline mass transfer, transport enhancement by mesopores is found to be, possibly, also caused by a reduction of transport resistances on the particle surfaces.

  19. Bioaccumulation d'un polychlorobiphényle commercial dans une chaîne trophodynamique expérimentale en eau douce

    Directory of Open Access Journals (Sweden)

    CAZIN J. C.

    1978-04-01

    Full Text Available Ce travail décrit les conditions d'expérimentation d'un polychlorobiphényle commercial sur les différents maillons d'une chaîne alimentaire en eau douce : algues-crustacés-poissons. Après avoir déterminé les modalités de contamination compatibles avec la croissance normale des organismes végétaux et animaux, les cinétiques de concentration au niveau de chaque espèce, l'association des différents maillons a permis d'apprécier l'importance du transfert biologique du polluant qui apparaît limité, aux environs de 10 ppm, par l'état d'équilibre qui s'installe progressivement dans le milieu aquatique.

  20. SYNTHESIS AND IDENTIFICATION OF 12 A-RING REDUCED 6-ALPHA-HYDROXYLATED AND 6-BETA-HYDROXYLATED COMPOUNDS DERIVED FROM 11-DEOXYCORTISOL, CORTICOSTERONE AND 11-DEHYDROCORTICOSTERONE

    NARCIS (Netherlands)

    KRAAN, GPB; HARTSTRA, J; WOLTHERS, BG; VANDERMOLEN, JC; NAGEL, GT; DRAYER, NM; ZIJLSTRA, RWJ; KRUIZINGA, WH

    The synthesis and identification of 12 A-ring reduced 6 alpha-(and 6 beta-)hydroxylated compounds derived from 11-deoxycortisol (S), corticosterone (B) and 11-dehydrocorticosterone (A) are reported here. These steroids were prepared in two steps from the corresponding 6 6 alpha-(and 6

  1. From the Brasserie to the Classroom: The Chaîne Des Puys - Limagne Fault Unesco World Heritage Project, Scientists and Non-Scientists Communicating Geoheritage

    Science.gov (United States)

    van Wyk de Vries, B.; Olive-Garcia, C.

    2014-12-01

    Geoheritage is an effective way of transferring scientific knowledge to non-peer audiences of all types. We present our experience of the Chaîne des Puys and Limagne fault UNESCO World heritage project, which shows how geoheritage can be a very successful communication tool, especially as it draws in the non-peers into the geological process at many levels. First and foremost is the local level, as no geoheritage project can be successful without local participation. Few geological localities on Earth are now devoid of human influence or habitation, and thus those who live and work on sites are the necessary first stage custodians. This means that locals must gain some understanding of their geology in order to appreciate their heritage. As such people tend to have a close relationship with their land, this is often half way done: local land use, customs are often easily integrated with geological knowledge. Once this link exists, communicating ideas that can be useful for management or for dealing with hazards is easier. Sometimes more tricky is communication to visitors, tourists and politicians who do not have such as close link to the landscape. Here, the educational strategy has to be different, with a need for them to learn what the landscape is and how it is managed, and lived in. During the development of the World Heritage Chaîne des Puys and Limagne Fault project the project team has been composed of geoscientists actively working on the area, agronomists local administration (such as natural park and local government members), and landscape specialists. Each has engaged in communication at different levels channelled either through personal contacts, or through more formal means, such as exhibitions, talks, and websites. Scientists have become communicators, and non-peers have begun to see the landscape though a geolologist eyes. A Geological landscape has begun to emerge in the popular perception.

  2. Atrial fibrillation, CHA2DS2-VASc score, antithrombotics and risk of non-traffic-, non-cancer-related bone fractures: A population-based cohort study.

    Science.gov (United States)

    Lai, Hui-Chin; Chien, Wu-Chien; Chung, Chi-Hsiang; Lee, Wen-Lieng; Wu, Tsu-Juey; Wang, Kuo-Yang; Liu, Chia-Ning; Liu, Tsun-Jui

    2015-12-01

    Accidental bone fractures are a major cause of premature disabilities and death. Whether atrial fibrillation (AF) treated with or without antithrombotics correlates with occurrence of such events remains under-investigated. Patients ≥18 years with newly diagnosed AF between 2005 and 2009 without previous cancers or traffic injury were identified from the "Longitudinal Health Insurance Database 2005" (1 million beneficiaries) of Taiwan's National Health Research Institutes and served as the AF group. A fourfold number of age-, gender-, and comorbidity-matched patients but without AF served as the non-AF controls. Patients were followed, and cumulative incidence of hospitalization-requiring bone fractures was compared between groups. Predictors of accidental bone fractures were determined by Cox regression analysis. Within a mean follow-up of 3.6 years, bone fractures, especially those involving neck/trunk and lower limbs, were significantly more frequent in patients with AF (N=6925) than in those without (N=27,700) (7.0 vs. 3.8 per 1000 person-years, log-rank p=0.001, adjusted HR=1.85, 95% CI=1.50-2.30, pbone fractures in AF patients, whereas oral anticoagulants (HR=0.62, 95% CI=0.35-0.91, p=0.034), especially when used in patients with CHA2DS2-VASc score≧1 but not antiplatelet therapy (p=0.39) as negative predictors. Patients with AF are more vulnerable to non-traffic-, non-cancer-related bone fractures especially when with specified characteristics. For those with higher CHA2DS2-VASc scores, the use of anticoagulant but not antiplatelet agents could be associated with lower risk of such events. Copyright © 2015 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  3. CHA(2)DS(2)-VASc versus CHADS(2) for stroke risk assessment in low-risk patients with atrial fibrillation: a pilot study from a single center of the NCDR-PINNACLE registry.

    Science.gov (United States)

    Piyaskulkaew, Chatchawan; Singh, Tejwant; Szpunar, Susan; Saravolatz, Louis; Rosman, Howard

    2014-05-01

    The CHADS(2) score is widely used to assess the risk of stroke in patients with atrial fibrillation (AF). Patients with score of 0 and 1 are considered 'low risk' and are often treated with aspirin. In a Danish Study, the CHA(2)DS(2)--VASc score was shown to identify low and high-risk subgroups among patients with CHADS(2) score of 0 and 1, with annual risk ranging from 0.84 to 8.18%. This study seeks to assess whether using CHA(2)DS(2)--VASc score will identify high-risk subset of patients with low CHADS(2) scores in an American population. This pilot study examined data from our cardiology fellowship ambulatory clinics from January 2009 to May 2012 using the NCDR-PINNACLE registry. Each cardiology fellow entered patients' data using on-line software developed by the American College of Cardiology. Among 2,048 patients followed at our clinics, 478 had AF. Of those, 161 patients had CHADS(2) score of 0 (44 patients) or 1 (117 patients). Calculating the CHA(2)DS(2)--VASc score in these patients, 12 (7.4%) had score of 0, 50 (31.1%) had score of 1, 66(41%) had score of 2, 31 (19.3%) had score of 3 and 2 (1.2%) had score of 4. Using original CHADS(2) recommendation, warfarin would not be strongly recommended in any of these patients. Utilizing the CHA(2)DS(2)--VASc score, 61.5% of the 161 patients would have a score of 2 or more signifying increased risk where anticoagulation may be indicated. Compared to CHADS(2), CHA(2)DS(2)--VASc may more precisely predict the risk of stroke and anticoagulation strategy in low-risk patients with non-valvular AF.

  4. The Value of CHA2DS2VASC Score in Predicting All-Cause Mortality in Patients with ST-Segment Elevation Myocardial Infarction Who Have Undergone Primary Percutaneous Coronary Intervention.

    Science.gov (United States)

    Keskin, Kudret; Sezai Yıldız, Süleyman; Çetinkal, Gökhan; Aksan, Gökhan; Kilci, Hakan; Çetin, Şükrü; Sığırcı, Serhat; Kılıçkesmez, Kadriye

    2017-11-01

    Acute coronary syndrome is the most common cause of cardiac morbidity and death. Various scoring systems have been developed in order to identify patients who are at risk for adverse outcome and may benefit from more aggressive and effective therapies. This study was designed to evaluate the CHA2DS2VASC score as a predictor of mortality inpatients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention (p-PCI). We evaluated 300 patients diagnosed with ST-elevation myocardial infarction who underwent p-PCI and calculated their CHA2DS2VASC scores. According to their CHA2DS2VASC scores, patients were divided into three groups. Group 1: 0-1 points (n = 101), Group 2: 2-3 points (n = 129), and Group 3: 4-9 points (n = 70). The mean, median and minimum duration of follow-up were 21.7 ± 9.4, 21, and 12 months, respectively. All-cause mortality was defined as the primary endpoint of the study. All-cause mortality was 4% in Group 1, 8.5% in Group 2 and 27.1% in Group 3 respectively. Kaplan-Meier analysis showed that Group 3 (CHA2DS2VASC ≥ 4) had a significantly higher incidence of death [p (log-rank) < 0.001]. In ROC analysis, AUC values for in hospital, 12-month and long-term mortality were 0.88 (0.77-0.99 95% CI), 0.82 (0.73-0.92 95% CI) and 0.79 (0.69-0.88 95% CI), respectively. CHA2DS2VASC score can be used for predicting both in-hospital, 12-month and long-term mortality in patients with STEMI who have undergone p-PCI.

  5. In-vitro synthesis of marble apatite as a novel adsorbent for removal of fluoride ions from ground water: An ultrasonic approach.

    Science.gov (United States)

    Mehta, Dhiraj; Mondal, Poonam; Saharan, Virendra Kumar; George, Suja

    2018-01-01

    Marble waste powder consisting of calcium and magnesium compounds was used to synthesize a novel biocompatible product, marble apatite (MA) primarily hydroxyapatite (Hap) for applications in defluoridation of drinking water. Synthesis of marble apatite was carried out by using calcium compounds (mixture of hydroxide and nitrate) extracted from marble waste powder which was treated with potassium dihydrogen phosphate at 80°C under alkaline conditions using conventional precipitation method (CM) and ultrasonication method (USM). Qualitative analysis of synthesized marble apatite from both the methods was carried out using FTIR, phase analysis by XRD and microstructure analysis by SEM and TEM. When ultrasonication (USM) method was used, the yield of marble apatite was improved from 67.5% to 78.4%, with reduction in crystallite size (58.46nm), lesser agglomeration and comparatively well-defined spherical morphology compared to the CM method. Studies also include estimation of the defluoridation capacity of MA as an adsorbent for drinking water treatment and effects of process parameters such as pH, contact time, initial fluoride concentration, dosage and presence of other co-ions on fluoride removal capacity. The results showed that the experimental adsorption capacity of the marble apatite synthesized using USM method was significantly higher (1.826mg/g) than marble apatite synthesized using conventional method (0.96mg/g) at pH 7 with a contact time of 90min. The mechanism of adsorption was studied, and it was observed that Langmuir isotherm model fitted best to the experimental data, while the kinetic studies revealed that the process followed pseudo-second order model. This novel compound, marble apatite synthesized from marble waste powder is found to be promising for defluoridation of drinking water and will help in alleviating the problems of fluorosis as well as reduce the problems of disposal of marble waste. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Inhibition of precipitation of carbonate apatite by trisodium citrate analysed in base of the formation of chemical complexes in growth solution

    Energy Technology Data Exchange (ETDEWEB)

    Prywer, Jolanta, E-mail: jolanta.prywer@p.lodz.pl [Institute of Physics, Lodz University of Technology, ul. Wólczańska 219, 93-005 Łódź (Poland); Olszynski, Marcin [Institute of Physics, Lodz University of Technology, ul. Wólczańska 219, 93-005 Łódź (Poland); Mielniczek-Brzóska, Ewa [Institute of Chemistry, Environment Protection and Biotechnology, Jan Długosz University of Częstochowa, ul. Armii Krajowej 13/15, 42-200 Częstochowa (Poland)

    2015-11-15

    Effect of trisodium citrate on the precipitation of carbonate apatite is studied. The experimental series are performed in the solution of artificial urine. The investigations are related to infectious urinary stones formation as carbonate apatite is one of the main components of this kind of stones. To mimic a real infection in urinary tract the aqueous ammonia solution was added to the solution of artificial urine. The spectrophotometric results demonstrate that trisodium citrate increases induction time with respect to carbonate apatite formation and decreases the efficiency of carbonate apatite precipitation. The inhibitory effect of trisodium citrate on the precipitation of carbonate apatite is explained in base of chemical speciation analysis. Such an analysis demonstrates that the inhibitory effect is mainly related with the fact that trisodium citrate binds Ca{sup 2+} ions and causes the formation of CaCit{sup −} and Ca{sub 10}(PO{sub 4}){sub 6}CO{sub 3} complexes. Trisodium citrate binds Ca{sup 2+} ions in the range of pH from 6 to 9.5 for which carbonate apatite is favored to be formed. - Highlights: • Trisodium citrate (TC) increases induction time of carbonate apatite (CA) formation. • TC decreases the efficiency of CA precipitation. • The inhibitory effect of TC is explained in base of chemical speciation analysis. • The inhibitory effect is mainly related with the fact that TC binds Ca{sup 2+} ions. • TC binds Ca{sup 2+} ions in the range of pH from 6 to 9.5 for which CA is formed.

  7. Inhibition of hydroxyl radical reaction with aromatics by dissolved natural organic matter

    Science.gov (United States)

    Lindsey, M.E.; Tarr, M.A.

    2000-01-01

    Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compound molecules bound to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanism for the observed inhibition is that hydroxyl radical formation occurs in microenvironmental sites remote from the aromatic compounds. In addition to changes in kinetics, pyrene hydroxyl radical reaction also exhibited a mechanistic change in the presence of fulvic acid. The mechanism changed from a reaction that was apparently firstorder in pyrene to one that was apparently secondorder in pyrene, indicating that pyrene self-reaction may have become the dominant mechanism in the presence of fulvic acid. Dissolved NOM causes significant changes in the rate and mechanism of hydroxyl radical degradation of aromatic compounds. Consequently, literature rate constants measured in pure water will not be useful for predicting the degradation of pollutants in environmental systems. The kinetic and mechanistic information in this study will be useful for developing improved degradation methods involving Fenton chemistry.Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compounds molecules bounds to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanisms for the observed inhibition is that hydroxyl radical

  8. Co-variability of S 6+ , S 4+ , and S 2- in apatite as a function of oxidation state: Implications for a new oxybarometer

    Energy Technology Data Exchange (ETDEWEB)

    Konecke, Brian A.; Fiege, Adrian; Simon, Adam C.; Parat, Fleurice; Stechern, André

    2017-03-01

    In this study, we use micro-X-ray absorption near-edge structures (μ-XANES) spectroscopy at the S K-edge to investigate the oxidation state of S in natural magmatic-hydrothermal apatite (Durango, Mexico, and Mina Carmen, Chile) and experimental apatites crystallized from volatile-saturated lamproitic melts at 1000 °C and 300 MPa over a broad range of oxygen fugacities [( Embedded Image , FMQ+1.2, FMQ+3; FMQ = fayalite-magnetite-quartz solid buffer]. The data are used to test the hypothesis that S oxidation states other than S6+ may substitute into the apatite structure. Peak energies corresponding to sulfate S6+ (~2482 eV), sulfite S4+ (~2478 eV), and sulfide S2- (~2470 eV) were observed in apatite, and the integrated areas of the different sulfur peaks correspond to changes in Embedded Image and bulk S content. Here, multiple tests confirmed that the S oxidation state in apatite remains constant when exposed to the synchrotron beam, at least for up to 1 h exposure (i.e., no irradiation damages). To our knowledge, this observation makes apatite the first mineral to incorporate reduced (S2-), intermediate (S4+), and oxidized (S6+) S in variable proportions as a function of the prevailing Embedded Image of the system. Apatites crystallized under oxidizing conditions (FMQ+1.2 and FMQ+3), where the S6+/STotal peak area ratio in the coexisting glass (i.e., quenched melt) is ~1, are dominated by S6+ with a small contribution of S4+, whereas apatites crystallizing at reduced conditions (FMQ) contain predominantly S2-, lesser amounts of S6+, and possibly traces of S4+. A sulfur oxidation state vs. S concentration analytical line transect across hydrothermally altered apatite from the Mina Carmen iron oxide-apatite (IOA) deposit (Chile) demonstrates that apatite can become enriched in S4+ relative to S6+, indicating metasomatic overprinting via a SO2-bearing fluid or vapor phase. This XANES study demonstrates that as the Embedded Image increases from FQM to FMQ+1.2 to FMQ

  9. Morphostructural development of the Eritrean rift flank (southern Red Sea) inferred from apatite fission track analysis

    Science.gov (United States)

    Abbate, Ernesto; Balestrieri, Maria Laura; Bigazzi, Giulio

    2002-11-01

    The Red Sea is one of the best exposed young rift basins in the world. Its flanks on both the African and Arabian sides are characterized by basement uplifts parallel to the margins and by active erosion. Through the integration of 37 new apatite fission track (FT) analyses and regional geology, we elucidate the uplift and denudational history of the Eritrean continental margin along the southern Red Sea and, in particular, the development, timing, and past and present morphostructural features of its onshore portion. FT data indicate that at around 20 Ma, the Eritrean margin was affected by a crustal cooling event due to a postrifting accelerated phase of denudation. This cooling has the same age as those already detected on the conjugate Arabian margin (Yemen and Saudi Arabia). FT ages increase from 10-20 to 300-400 Ma with increasing distance and elevation from the coastal areas toward the interior. This trend indicates a diminishing amount of eroded section in the same direction. We use FT and structural data to define the position of the main border fault along the margin where the original scarp was located. We estimate rates of vertical denudation of 190-200 m/Myr at the border fault and of ≤60-70 m/Myr on the plateau. On the basis of these new data, we argue against an Oligocene tectonic unroofing of the margin through a low-angle detachment assumed by previous authors, but we maintain the essential role of the erosional denudation in the development of present margin morphology.

  10. Stability and heavy metal distribution of soil aggregates affected by application of apatite, lime, and charcoal.

    Science.gov (United States)

    Cui, Hongbiao; Ma, Kaiqiang; Fan, Yuchao; Peng, Xinhua; Mao, Jingdong; Zhou, Dongmei; Zhang, Zhongbin; Zhou, Jing

    2016-06-01

    Only a few studies have been reported on the stability and heavy metal distribution of soil aggregates after soil treatments to reduce the availability of heavy metals. In this study, apatite (22.3 t ha(-1)), lime (4.45 t ha(-1)), and charcoal (66.8 t ha(-1)) were applied to a heavy metal-contaminated soil for 4 years. The stability and heavy metal distribution of soil aggregates were investigated by dry and wet sieving. No significant change in the dry mean weight diameter was observed in any treatments. Compared with the control, three-amendment treatments significantly increased the wet mean weight diameter, but only charcoal treatment significantly increased the wet aggregate stability. The soil treatments increased the content of soil organic carbon, and the fraction 0.25-2 mm contained the highest content of soil organic carbon. Amendments' application slightly increased soil total Cu and Cd, but decreased the concentrations of CaCl2 -extractable Cu and Cd except for the fraction 2 and 0.25-2 mm contained the highest concentrations of CaCl2-extractable Cu and Cd, accounted for about 74.5-86.8 % of CaCl2-extractable Cu and Cd in soil. The results indicated that amendments' application increased the wet soil aggregate stability and decreased the available Cu and Cd. The distribution of available heavy metals in wet soil aggregates was not controlled by soil aggregate stability, but possibly by soil organic carbon.

  11. Chemical-physical Properties and Apatite-forming Ability of Mineral Trioxide Aggregate Flow.

    Science.gov (United States)

    Guimarães, Bruno Martini; Vivan, Rodrigo Ricci; Piazza, Bruno; Alcalde, Murilo Priori; Bramante, Clovis Monteiro; Duarte, Marco Antonio Hungaro

    2017-10-01

    This study aimed to analyze the chemical-physical properties, including pH, volumetric change, radiopacity, and apatite-forming ability in simulated body fluid, of a new tricalcium silicate material (MTA Flow; Ultradent Products Inc, South Jordan, UT). MTA Flow was tested in comparison with MTA Angelus (Angelus, Londrina, PR, Brazil). The pH of soaking water was tested up to 168 hours in deionized water. In the solubility test, the root-end fillings of 20 acrylic teeth were scanned twice by micro-computed tomographic imaging before and after immersion in ultrapure water for 168 hours. In addition, using an aluminum step wedge, the radiopacity of each material was evaluated as recommended by international standards. The mean gray values of the test materials were measured using ImageJ software (National Institutes of Health, Bethesda, MD). The morphologic and chemical analyses of the material surface were performed using scanning electron microscopic energy-dispersive X-ray spectroscopic analysis after 28 days in Hank's balanced salt solution (HBSS). The data were analyzed using 2-way analysis of variance with the Student-Newman-Keuls test (P Flow showed similar alkalizing activity to that of MTA Angelus. In the solubility test, both materials presented lower values without statistical differences. Both materials showed a marked alkalinizing activity within 3 hours, which continued for 168 hours. MTA Angelus showed statistically higher radiopacity values (P materials showed the ability to nucleate calcium phosphate on their surface after 28 days in HBSS. MTA Flow showed remarkable alkalinizing capability, low solubility, good radiopacity, and the ability to form calcium phosphate deposits after being soaked in simulated body fluid, showing values similar to those of MTA Angelus. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Detection and characterization of serine and threonine hydroxyl protons in Bacillus circulans xylanase by NMR spectroscopy.

    Science.gov (United States)

    Brockerman, Jacob A; Okon, Mark; McIntosh, Lawrence P

    2014-01-01

    Hydroxyl protons on serine and threonine residues are not well characterized in protein structures determined by both NMR spectroscopy and X-ray crystallography. In the case of NMR spectroscopy, this is in large part because hydroxyl proton signals are usually hidden under crowded regions of (1)H-NMR spectra and remain undetected by conventional heteronuclear correlation approaches that rely on strong one-bond (1)H-(15)N or (1)H-(13)C couplings. However, by filtering against protons directly bonded to (13)C or (15)N nuclei, signals from slowly-exchanging hydroxyls can be observed in the (1)H-NMR spectrum of a uniformly (13)C/(15)N-labeled protein. Here we demonstrate the use of a simple selective labeling scheme in combination with long-range heteronuclear scalar correlation experiments as an easy and relatively inexpensive way to detect and assign these hydroxyl proton signals. Using auxtrophic Escherichia coli strains, we produced Bacillus circulans xylanase (BcX) labeled with (13)C/(15)N-serine or (13)C/(15)N-threonine. Signals from two serine and three threonine hydroxyls in these protein samples were readily observed via (3)JC-OH couplings in long-range (13)C-HSQC spectra. These scalar couplings (~5-7 Hz) were measured in a sample of uniformly (13)C/(15)N-labeled BcX using a quantitative (13)C/(15)N-filtered spin-echo difference experiment. In a similar approach, the threonine and serine hydroxyl hydrogen exchange kinetics were measured using a (13)C/(15)N-filtered CLEANEX-PM pulse sequence. Collectively, these experiments provide insights into the structural and dynamic properties of several serine and threonine hydroxyls within this model protein.

  13. Post-translational hydroxylation by 2OG/Fe(II-dependent oxygenases as a novel regulatory mechanism in bacteria

    Directory of Open Access Journals (Sweden)

    Laura M van Staalduinen

    2015-01-01

    Full Text Available Protein hydroxylation has been well-studied in eukaryotic systems. The structural importance of hydroxylation of specific proline and lysine residues during collagen biosynthesis is well established while, recently, key roles for post-translational hydroxylation in signalling and degradation pathways have been discovered. The function of hydroxylation in signalling is highlighted by its role in the hypoxic response of eukaryotic cells, where oxygen dependent hydroxylation of the hypoxia inducible transcription factor both targets it for degradation and blocks its activation. In contrast, the role of protein hydroxylation has been largely understudied in prokaryotes. Recently, an evolutionarily conserved class of ribosomal oxygenases (ROX that catalyze the hydroxylation of specific residues in the ribosome has been identified in bacteria. ROX activity has been linked to cell growth, and has been found to have a direct impact on bulk protein translation. This discovery of ribosomal protein hydroxylation in bacteria could lead to new therapeutic targets for regulating bacterial growth, as well as, shed light on new prokaryotic hydroxylation signalling pathways. In this review, recent structural and functional studies will be highlighted and discussed, underscoring the regulatory potential of post-translational hydroxylation in bacteria.

  14. 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

    The release of nutritive elements through apatite dissolution represents the main source of phosphorus, calcium, and several micronutrients (e.g., Zn, Cu) for organisms in non-fertilized forest ecosystems. The aim of this study was to quantify, for the first time, the dissolution rate of apatite grains by tree roots that were or were not associated with a mineral weathering bacterial strain, and by various acids known to be produced by tree roots and soil bacterial strains in open-system flow microcosms. In addition, we explored whether the mobilization of trace elements (including rare earth elements) upon apatite dissolution was affected by the presence of trees and associated microorganisms. The dissolution rate of apatite by Scots pine plants that were or were not inoculated with the strain Burkholderia glathei PML1(12)Rp, and by inorganic (nitric) and organic (citric, oxalic and gluconic) acids at pH 5.5, 4.8, 3.8, 3.5, 3.0, and 2.0 was monitored in two controlled experiments: "plant-bacteria interaction" and "inorganic and organic acids". Analyses of the outlet solutions in the "plant-bacteria interaction" experiment showed that Scots pine roots and B. glathei PML1(12)Rp produced protons and organic acids such as gluconate, oxalate, acetate, and lactate. The weathering budget calculation revealed that Scots pines (with or without PML1(12)Rp) significantly increased (factor > 10) the release of Ca, P, As, Sr, Zn, U, Y, and rare earth elements such as Ce, La, Nd from apatite, compared to control abiotic treatment. Scanning electron microscopy observation confirmed traces of apatite dissolution in contact of roots. Most dissolved elements were taken up by Scots pine roots, i.e., approximately 50% of Ca, 70% of P, 30% of As, 70% of Sr, 90% of Zn, and 100% of U, Y, and rare earth elements. Interestingly, no significant additional effect due to the bacterial strain PML1(12)Rp on apatite dissolution and Scots pine nutrition and growth was observed. The "inorganic

  15. Effect of hot water and heat treatment on the apatite-forming ability of titania films formed on titanium metal via anodic oxidation in acetic acid solutions.

    Science.gov (United States)

    Cui, Xinyu; Kim, Hyun-Min; Kawashita, Masakazu; Wang, Longbao; Xiong, Tianying; Kokubo, Tadashi; Nakamura, Takashi

    2008-04-01

    Titanium and its alloys have been widely used for orthopedic implants because of their good biocompatibility. We have previously shown that the crystalline titania layers formed on the surface of titanium metal via anodic oxidation can induce apatite formation in simulated body fluid, whereas amorphous titania layers do not possess apatite-forming ability. In this study, hot water and heat treatments were applied to transform the titania layers from an amorphous structure into a crystalline structure after titanium metal had been anodized in acetic acid solution. The apatite-forming ability of titania layers subjected to the above treatments in simulated body fluid was investigated. The XRD and SEM results indicated hot water and/or heat treatment could greatly transform the crystal structure of titania layers from an amorphous structure into anatase, or a mixture of anatase and rutile. The abundance of Ti-OH groups formed by hot water treatment could contribute to apatite formation on the surface of titanium metals, and subsequent heat treatment would enhance the bond strength between the apatite layers and the titanium substrates. Thus, bioactive titanium metals could be prepared via anodic oxidation and subsequent hot water and heat treatment that would be suitable for applications under load-bearing conditions.

  16. 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.

  17. 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.

  18. Evaluation of the Ca ion release, pH and surface apatite formation of a prototype tricalcium silicate cement.

    Science.gov (United States)

    Yamamoto, S; Han, L; Noiri, Y; Okiji, T

    2017-12-01

    To evaluate the Ca 2+ -releasing, alkalizing and apatite-like surface precipitate-forming abilities of a prototype tricalcium silicate cement, which was mainly composed of synthetically prepared tricalcium silicate and zirconium oxide radiopacifier. The prototype tricalcium silicate cement, white ProRoot MTA (WMTA) and TheraCal LC (a light-cured resin-modified calcium silicate-filled material) were examined. The chemical compositions were analysed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyser with an image observation function (SEM-EPMA). The pH and Ca 2+ concentrations of water in which the set materials had been immersed were measured, and the latter was assessed with the EDTA titration method. The surface precipitates formed on the materials immersed in phosphate-buffered saline (PBS) were analysed with SEM-EPMA and X-ray diffraction (XRD). Kruskal-Wallis tests followed by Mann-Whitney U-test with Bonferroni correction were used for statistical analysis (α = 0.05). The prototype cement contained Ca, Si and Zr as major elemental constituents, whereas it did not contain some metal elements that were detected in the other materials. The Ca 2+ concentrations and pH of the immersion water samples exhibited the following order: WMTA = prototype cement > TheraCal LC (P prototype cement and WMTA. The prototype tricalcium silicate cement exhibited similar Ca 2+ -releasing, alkalizing and apatite-like precipitate-forming abilities to WMTA. The Ca 2+ -releasing, alkalizing and apatite-like precipitate-forming abilities of TheraCal LC were lower than those of the other materials. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  19. Sensitive determination of endogenous hydroxyl radical in live cell by a BODIPY based fluorescent probe.

    Science.gov (United States)

    Lei, Kepeng; Sun, Mingtai; Du, Libo; Zhang, Xiaojie; Yu, Huan; Wang, Suhua; Hayat, Tasawar; Alsaedi, Ahmed

    2017-08-01

    The sensitive and selective fluorescence probe for hydroxyl radical analysis is of significance because hydroxyl radical plays key roles in many physiological and pathological processes. In this work, a novel organic fluorescence molecular probe OHP for hydroxyl radical is synthesized by a two-step route. The probe employs 4-bora-3a,4a-diaza-s-indacene (difluoroboron dipyrromethene, BODIPY) as the fluorophore and possesses relatively high fluorescence quantum yields (77.14%). Hydroxyl radical can rapidly react with the probe and quench the fluorescence in a good linear relationship (R2=0.9967). The limit of detection is determined to be as low as 11nM. In addition, it has been demonstrated that the probe has a good stability against pH and light illumination, low cytotoxicity and high biocompatibility. Cell culture experimental results show that the probe OHP is sensitive and selective for imaging and tracking endogenous hydroxyl radical in live cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. A comparison of fenuron degradation by hydroxyl and carbonate radicals in aqueous solution.

    Science.gov (United States)

    Mazellier, Patrick; Busset, Cécile; Delmont, Anne; De Laat, Joseph

    2007-12-01

    A comparative study of the transformation of the herbicide fenuron (1,1-dimethyl-3-phenylurea) by hydroxyl radicals and carbonate radicals in aqueous solution (pH 7.2-phosphate buffer) has been undertaken. Hydroxyl radical was generated by the well-known photolysis of hydrogen peroxide at 254 nm and carbonate radical was formed by photolysis of Co(NH(3))(5)CO(3)(+) at 254 nm. Competitive kinetic experiments were performed with atrazine used as the main competitor for both processes. Accordingly, the second-order rate constant of reaction between fenuron and carbonate radical was found to be (7-12+/-3)x10(6)M(-1)s(-1) [(7+/-1)x10(9)M(-1)s(-1) for hydroxyl radical]. The formation of degradation products was studied by LC-MS in the two cases and a comparison has been performed. The reaction with carbonate radical leads to the formation of a quinone-imine derivative which appears as the major primary product together with ortho and para hydroxylated compounds. These two compounds represent the major products in the reaction with hydroxyl radicals. The reaction of both radicals also leads to the transformation of the dimethylurea moiety.

  1. Subterminal hydroxylation of lauric acid by microsomes from a marine fish.

    Science.gov (United States)

    Lemaire, P; Lafaurie, M; Weissbart, D; Durst, F; Pflieger, P; Mioskowski, C; Salaün, J P

    1992-03-01

    Microsomes from the liver of sea bass (Dicentrarchus labrax) were shown to hydroxylate lauric acid at subterminal positions. The cytochrome P-450 system converted lauric acid to several mono-hydroxylated metabolites including omega-1 hydroxylaurate, which was the major metabolite (44% of total products). In addition, omega-2, omega-3, omega-4 and a small amount (2.3%) of omega hydroxylaurates were found. Reaction products were identified using thin-layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS). Oxidation reactions were dependent upon O2 and NADPH, and did not occur with boiled microsomes or in the presence of a mixture of CO/O2. Hydroxylation proceeded linearly up to 20 min at 28 degrees C for protein concentrations below 380 micrograms. Treatment of fish with benzo(a)pyrene (BP) (20 mg/kg) drastically increased xenobiotic metabolism (ECOD, EROD and BPMO activities), but no difference in laurate hydroxylase activity was observed between untreated and treated fish. Starvation strongly enhanced laurate hydroxylase activity, and resumption of feeding reduced by half this increase of activity. In all of the experiments we did not observe any modification of the regioselectivity of lauric acid hydroxylation by this microsomal in-chain hydroxylating system. We suggest that cytochrome P-450 enzymes involved in lauric acid and xenobiotics metabolism are regulated independently.

  2. Opto-impedance characteristics of europium doped strontium aluminate and strontium chloro-apatite phosphors: a comparison

    Energy Technology Data Exchange (ETDEWEB)

    Syed, K A Z; Kaleeswari, P; Thirumalai, J; Manoharan, S P; Raj, A Sundara; Jagannathan, R [Central Electrochemical Research Institute, Karaikudi-630006, TN (India)], E-mail: jags57_99@yahoo.com

    2008-09-07

    Opto-impedance characteristics of the long persistent strontium aluminate : Eu{sup 2+} phosphor system have been compared with fluorescent strontium chloro-apatite : Eu{sup 2+} phosphor. This study has shown that optical pumping on the long persistent phosphor sample leads to a type of charge build-up and subsequent dispersion through a diffusion process occurring on a slow time scale ({approx}s) centring on the Dy{sup 3+} ion in agreement with a three-level scheme based on Dy{sup 3+} related hole-trapping-detrapping mechanism.

  3. Effect of water vapor treatment on apatite formation on precalcified titanium and bond strength of coatings to substrates.

    Science.gov (United States)

    Feng, B; Chen, Y; Zhang, X D

    2002-01-01

    In previous investigations, a simple method, precalcification, was developed for bioactivating titanium. After a titanium sample was precalcified in a boiling saturated Ca(OH)(2) solution and then immersed in a calcium phosphate supersaturated solution, an apatite coating rapidly precipitated onto its surface. In the present study, heat-treatment in water vapor was carried out prior to precalcification. Heat-treatment in water vapor stimulated the chemical reaction between titanium, calcium, and phosphate. Coating properties were improved, and the bond strength of the coating to substrate was enhanced. Copyright 2001 John Wiley & Sons, Inc.

  4. Luminescence of Eu(III), Pr(III) and Sm(III) in carbonate-fluor-apatite

    Energy Technology Data Exchange (ETDEWEB)

    Gaft, M.; Shoval, S. [The Open University, Physics and Geology Groups, Tel-Aviv (Israel); Reisfeld, R. [Department of Inorganic and Analytical Chemistry, The Hebrew University, Jerusalem (Israel); Panczer, G.; Garapon, C.; Boulon, G. [University of Claude Bernard, Lyon (France)]|[Physico-Chimie des Materiaux Luminescents, CNRS, Villeurbanne (France); Strek, W. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland)

    1996-12-31

    The purpose of this work was identification of luminescent lines occurring in natural carbonate-fluor-apatite (francolite) mineral. For identification of several rare earth ions occurring in natural francolite, the luminescence of rare earth ions was extensively studied in artificial mineral consisting of pure francolite (not containing rare earth) of the composition Ca{sub 5}(PO{sub 4}){sub 3}(F,O):Ca{sub 5}(PO{sub 4}){sub 3}CO{sub 3} activated with Pr, Eu and Sm ions and then compared with the luminescence features observed in natural mineral. (author) 16 refs, 7 figs

  5. Preparation of a non-woven poly(ε-caprolactone) fabric with partially embedded apatite surface for bone tissue engineering applications by partial surface melting of poly(ε-caprolactone) fibers.

    Science.gov (United States)

    Kim, In Ae; Rhee, Sang-Hoon

    2017-07-01

    This article describes a novel method for the preparation of a biodegradable non-woven poly(ε-caprolactone) fabric with a partially embedded apatite surface designed for application as a scaffold material for bone tissue engineering. The non-woven poly(ε-caprolactone) fabric was generated by the electro-spinning technique and then apatite was coated in simulated body fluid after coating the PVA solution containing CaCl2 ·2H2 O. The apatite crystals were partially embedded or fully embedded into the thermoplastic poly(ε-caprolactone) fibers by controlling the degree of poly(ε-caprolactone) fiber surface melting in a convection oven. Identical apatite-coated poly(ε-caprolactone) fabric that did not undergo heat-treatment was used as a control. The features of the embedded apatite crystals were evaluated by FE-SEM, AFM, EDS, and XRD. The adhesion strengths of the coated apatite layers and the tensile strengths of the apatite coated fabrics with and without heat-treatment were assessed by the tape-test and a universal testing machine, respectively. The degree of water absorbance was assessed by adding a DMEM droplet onto the fabrics. Moreover, cell penetrability was assessed by seeding preosteoblastic MC3T3-E1 cells onto the fabrics and observing the degrees of cell penetration after 1 and 4 weeks by staining nuclei with DAPI. The non-woven poly(ε-caprolactone) fabric with a partially embedded apatite surface showed good water absorbance, cell penetrability, higher apatite adhesion strength, and higher tensile strength compared with the control fabric. These results show that the non-woven poly(ε-caprolactone) fabric with a partially embedded apatite surface is a potential candidate scaffold for bone tissue engineering due to its strong apatite adhesion strength and excellent cell penetrability. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1973-1983, 2017. © 2017 Wiley Periodicals, Inc.

  6. State-Resolved Dynamics of the CN(B2Sigma+) and CH(A2Delta)Excited Products Resulting from the VUV Photodissociation of CH3CN

    Energy Technology Data Exchange (ETDEWEB)

    Howle, Chris R.; Arrowsmith, Alan N.; Chikan, Viktor; Leone,Stephen R.

    2007-01-18

    Fourier transform visible spectroscopy, in conjunction withVUV photons produced by a synchrotron, is employed to investigate thephotodissociation of CH3CN. Emission is observed from both theCN(B2Sigma+ - X2Sigma+) and CH(A2Delta - X2PI) transitions; only theformer is observed in spectra recorded at 10.2 and 11.5 eV, whereas bothare detected in the 16 eV spectrum. The rotational and vibrationaltemperatures of both the CN(B2Sigma+) and CH(A2Delta) radical productsare derived using a combination of spectral simulations and Boltzmannplots. The CN(B2Sigma+) fragment displays a bimodal rotationaldistribution in all cases. Trot(CN(B2Sigma+)) ranges from 375 to 600 K atlower K' and from 1840 to 7700 K at higher K' depending on the photonenergy used. Surprisal analyses indicate clear bimodal rotationaldistributions, suggesting CN(B2Sigma+) is formed via either linear orbent transition states, respectively, depending on the extent ofrotational excitation in this fragment. CH(A2Delta) has a singlerotational distribution when produced at 16 eV which results inTrot(CH(A2Delta)) = 4895 +- 140 K in nu' = 0 and 2590 +- 110 K in nu' =1. From thermodynamic calculations, it is evident that CH(A2Delta) isproduced along with CN(X2Sigma+) + H2. These products can be formed by atwo step mechanism (via excited CH3* and ground state CN(X2Sigma+) or aprocess similar to the "roaming" atom mechanism; the data obtained hereare insufficient to definitively conclude whether either pathway occurs.A comparison of the CH(A2Delta) and CN(B2Sigma+) rotational distributionsproduced by 16 eV photons allows the ratio between the two excitedfragments at this energy to be determined. An expression that considersthe rovibrational populations of both band systems results in aCH(A2Delta):CN(B2Sigma+) ratio of (1.2 +- 0.1):1 at 16 eV, therebyindicating that production of CH(A2Delta) is significant at 16eV.

  7. Palladium(II) complexes bearing a salicylaldiminato ligand with a hydroxyl group: Synthesis, structures, deprotonation, and catalysis

    OpenAIRE

    Murata, Yusuke; Ohgi, Hiroyuki; Fujihara, Tetsuaki; Terao, Jun; Tsuji, Yasushi

    2011-01-01

    Palladium complexes with a salicylaldiminato ligand bearing a hydroxyl group (1a and 1b) have been synthesized and characterized. The structures of these complexes were confirmed by X-ray crystallography. A reversible deprotonation/protonation of the hydroxyl moiety on 1b was observed, while such behaviour was impossible with a related palladium complex (1c) bearing a methoxyl group in place of the hydroxyl group. The deprotonation affected its catalytic behaviour: the activity for polymeriza...

  8. Hydroxyl radical "footprinting": high-resolution information about DNA-protein contacts and application to lambda repressor and Cro protein.

    OpenAIRE

    Tullius, T D; Dombroski, B A

    1986-01-01

    A method has been developed for making "footprints" of proteins bound to DNA. The hydroxyl radical, generated by reduction of hydrogen peroxide by iron(II), is the reagent used to cut the DNA. Hydroxyl radical breaks the backbone of DNA with almost no sequence dependence, so all backbone positions may be monitored for contact with protein. In addition to defining the DNA sequence in contact with the protein, hydroxyl radical footprints embody structural information about the DNA-protein compl...

  9. Chemisorption of hydrogen atoms and hydroxyl groups on stretched graphene: A coupled QM/QM study

    Science.gov (United States)

    Katin, Konstantin P.; Prudkovskiy, Vladimir S.; Maslov, Mikhail M.

    2017-09-01

    Using the density functional theory coupled with the nonorthogonal tight-binding model, we analyze the chemisorption of hydrogen atoms and hydroxyl groups on the unstrained and stretched graphene sheets. Drawback of finite cluster model of graphene for the chemisorption energy calculation in comparison with the QM/QM approach applied is discussed. It is shown that the chemisorption energy for the hydroxyl group is sufficiently lower than for hydrogen at stretching up to 7.5%. The simultaneous paired chemisorption of hydrogen and hydroxyl groups on the same hexagon has also been examined. Adsorption of two radicals in ortho and para positions is found to be more energetically favorable than those in meta position at any stretching considered. In addition the energy difference between adsorbent pairs in ortho and para positions decreases as the stretching rises. It could be concluded that the graphene stretching leads to the loss of preferred mutual arrangement of two radicals on its surface.

  10. Influence of hydroxylation and glycosylation in ring A of soybean isoflavones on interaction with BSA

    Science.gov (United States)

    Zhao, Jinyao; Ren, Fenglian

    2009-04-01

    In this paper, the influence of hydroxylation and glycosylation of soybean isoflavones in ring A on the interaction with BSA was investigated. Two soybean isoflavone aglycones (daidzein and genistein) and their glycosides (daidzin and genistin) were used to study their ability to bind BSA by quenching the BSA intrinsic fluorescence in solution. The hydroxylation and glycosylation of soybean isoflavones in ring A significantly affected the binding/quenching process; in general, the hydroxylation increases the binding affinity and the glycosylation decreased the binding affinity. For daidzein and daidzin, the binding constants for BSA were 5.2 × 10 4 and 5.58 × 10 3 L mol -1, respectively. For genistein and genistin, the binding constants were 8.40 × 10 5 and 1.44 × 10 5 L mol -1, respectively.

  11. Hydroxylation of steroids with nonpolar side chains with 11 alpha-hydroxylase of Rhizopus nigricans.

    Science.gov (United States)

    Zakelj-Mavric, M; Kastelic-Suhadolc, T; Gottlieb, H E; Belic, I

    1989-08-01

    Steroids with nonpolar side chains with 2, 4 and 8 C atoms were used as substrates for the 11 alpha-hydroxylase of Rhizopus nigricans. Their bioconversion was compared to that of progesterone, which was found to be far the best substrate giving the highest total bioconversion. 3-keto-4-ene steroids with nonpolar side chains were converted to their hydroxylated products in a small yield or not at all. The absence of an oxygen function in the side chain did not affect the regio-specificity of the hydroxylation, but resulted in a much lower total bioconversion. The strong effect of the oxygen function and of the length of the side chain on hydroxylation with the 11 alpha-hydroxylase of Rhizopus nigricans was demonstrated.

  12. OH, the Places You'll Go! Hydroxylation, Gene Expression, and Cancer.

    Science.gov (United States)

    Ploumakis, Athanasios; Coleman, Mathew L

    2015-06-04

    Hydroxylation is an emerging modification generally catalyzed by a family of ∼70 enzymes that are dependent on oxygen, Fe(II), ascorbate, and the Kreb's cycle intermediate 2-oxoglutarate (2OG). These "2OG oxygenases" sit at the intersection of nutrient availability and metabolism where they have the potential to regulate gene expression and growth in response to changes in co-factor abundance. Characterized 2OG oxygenases regulate fundamental cellular processes by catalyzing the hydroxylation or demethylation (via hydroxylation) of DNA, RNA, or protein. As such they have been implicated in various syndromes and diseases, but particularly cancer. In this review we discuss the emerging role of 2OG oxygenases in gene expression control, examine the regulation of these unique enzymes by nutrient availability and metabolic intermediates, and describe these properties in relation to the expanding role of these enzymes in cancer. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. The Reaction of Allyl Isothiocyanate with Hydroxyl/Water and β-Cyclodextrin Using Ultraviolet Spectrometry

    Directory of Open Access Journals (Sweden)

    Zi-Tao Jiang

    2006-01-01

    Full Text Available The reaction of allyl isothiocyanate (AITC with hydroxyl/water and β-cyclodextrin (β-CD in different acidic-alkaline media has been investigated by ultraviolet spectrometry. The kinetic parameters of the reaction were measured. It was found that after AITC translating into thiourea, the absorption peak shifted from 240 to 226 nm and the molar absorptivity increased about 16 times. The reaction can be seen as a pseudo first order reaction because the concentration of hydroxyl was constant. β-CD can inhibit the reaction of AITC with hydroxyl/water, i.e. the hydrolysis of AITC. The formation constant (Ka and thermodynamic parameters of the complex reaction were calculated. Ka decreased with the increase of temperature. The experimental results indicated that the inclusive process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution.

  14. Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

    DEFF Research Database (Denmark)

    Thybring, Emil Engelund; Thygesen, Lisbeth Garbrecht; Burgert, Ingo

    2017-01-01

    The first drying of wood cell walls from the native state has sometimes been described as producing irreversible structural changes which reduce the accessibility to water, a phenomenon often referred to as hornification. This study demonstrates that while changes do seem to take place......, these are more complex than what has hitherto been described. The accessibility of wood cell wall hydroxyls to deuteration in the form of liquid water was not found to be affected by drying, since vacuum impregnation with liquid water restores the native cell wall accessibility. Contrary to this, hydroxyl...... to 1 day. Moreover, the decrease in hydroxyl accessibility to deuteration by water vapour induced by the first drying could be at least partially erased by subsequent vacuum impregnation with liquid water, indicating reversibility. For the drying of solid, non-degraded wood cell walls the results...

  15. 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)

  16. Sarcoplasmic reticulum Ca(2+)-pump dysfunction in rat cardiomyocytes briefly exposed to hydroxyl radicals.

    Science.gov (United States)

    Morris, T E; Sulakhe, P V

    1997-01-01

    The effects of hydroxyl radical exposure of intact cardiomyocytes on sarcoplasmic reticulum (SR) function were investigated. For this purpose, isolated rat heart myocytes were exposed briefly (1 min) to the hydroxyl radical generating system (H2O2/FeCl2 or FeSO4) or 5-5'-dithiobis-nitrobenzoic acid (DTNB), a sulfhydryl oxidizing reagent, and following this a SR-enriched fraction was isolated. Marked decreases in the SR calcium uptake activities were seen in the myocytes exposed to either the hydroxyl radical-generating system or DTNB. The exposure of myocytes to the hydroxyl radical, but not DTNB, markedly increased the amount of malonyldialdehyde (MDA) in the subsequently isolated SR. Total sulfhydryl group content in SR was decreased by exposure of myocytes to DTNB. Further, there was a significant decrease in [3H]-NEM binding to SR isolated from the hydoxyl radical-treated myocytes indicating that sulfhydryl groups are affected (oxidized). Both mannitol and catalase were found to offer complete protection against the inhibitory effect of peroxide +/- iron on calcium uptake. Also the above-mentioned alterations in both MDA and sulfhydryl group content were prevented by mannitol and catalase. Exogenously added cyclic AMP-dependent protein kinase (A-PK) or calmodulin (CAM) increased SR calcium uptake activity. In the SR isolated from the treated myocytes, the stimulatory effects of A-PK and CAM were also seen, although under all assay conditions calcium uptakes were of lower magnitude. The findings are consistent with the view that the damaging effect of the hydroxyl radical and DTNB on the functioning of SR occurs rapidly in the intact cardiomyocytes. The hydroxyl radical-provoked damage involves both protein sulfhydryl and lipid oxidation.

  17. Development and functioning of microorganisms in concentration cycles of sulfide copper-nickel and non-sulfide apatite-nepheline ores

    Directory of Open Access Journals (Sweden)

    Fokina N. V.

    2017-03-01

    Full Text Available The number and trophic diversity of bacteria in flotation samples of apatite-nepheline and sulfide copper-nickel ores at the concentration plants of JSC "Apatite" and Kola Mining and Metallurgical Company have been determined. The study of the size and diversity of the microbiota has been conducted by culture on selective nutrient media. The total number and biomass of bacteria have been considered by fluorescence microscopy using Cyclopore polycarbonate membrane filters. Bacteria have been identified by molecular genetic methods. The least amount of both saprotrophic and other trophic groups of bacteria has been observed in the samples of ore and recycled water as at the concentrating factory of Apatit JSC, and also at the plant "Pechenganikel". It has been found out that the bacteria contained in the ore and recycling water flowing from the tailings increased their number during the flotation process due to coming of the nutrients with the flotation reagents, aeration and increased temperature. Strains which occurrence is more than 60 % have been extracted from recycled water and basic flotation products and classified as Pseudomonas. Two strains with occurrence of more than 60 % have been discovered at Apatit JSC and classified as Stenotrophomonas and Acinetobacter. The number of fungi in the cycle of apatite-nepheline ore enrichment at the factories is very low (1 to 24 CFU / 1 ml or 1 g of ore. Fungi of the genus Penicillium have been dominated, fungi of the genera Acremonium, Aureobasidium, Alternaria, Chaetomium have also been detected. At the plant "Pechenganikel" species Aspergillus fumigatus, Penicillium aurantiogriseum and P. glabrum have been extracted. It has been shown that the bacteria deteriorate the apatite flotation as a result of their interaction with active centers of calcium-containing minerals and intensive flocculation decreasing the floatation selectivity. Also some trend of copper and nickel recovery change has been

  18. Effect of indole-3-acetic acid on pea root growth, peroxidase profiles and hydroxyl radical formation

    Directory of Open Access Journals (Sweden)

    Kukavica Biljana

    2007-01-01

    Full Text Available Changes in growth, peroxidase profiles, and hydroxyl radical formation were examined in IAA (0.5-10 mg/l treated pea plants grown hydroponically and in isolated roots in liquid in vitro culture. IAA inhibited root elongation, both in hydroponically grown pea plants and in isolated roots in vitro. A remarkable increase in the number of POD iso­forms was noticed in isolated roots grown in vitro, compared to the roots from plants grown hydroponically. IAA induced both disappearance of several root POD isoforms and hydroxyl radical formation in the root and the root cell wall.

  19. Autocatalytic surface hydroxylation of MgO(100) terrace sites observed under ambient conditions

    DEFF Research Database (Denmark)

    Newberg, J.T.; Mysak, E.R.; Bluhm, H.

    2011-01-01

    We have investigated the reaction of water vapor with the MgO(100) surface using ambient pressure X-ray photoelectron spectroscopy (AP-XPS), which permits the study of the chemical composition of the MgO/water vapor interface at p(H2O) in the Torr range. Water dissociation on thin MgO(100) films...... interacting with a fully hydroxylated interface on MgO(100). The observed onset of hydroxylation near 0.01% RH is suggested to be due to water molecules aggregating at the surface, leading to an autocatalytic dissociation of water at MgO(100) terrace sites....

  20. Formation of hydroxyl radicals in the human lens is related to the severity of nuclear cataract

    DEFF Research Database (Denmark)

    Garner, B; Davies, Michael Jonathan; Truscott, R J

    2000-01-01

    Recent studies have identified specific hydroxylated amino acid oxidation products which strongly suggest the presence of hydroxyl radical (HO.)-damaged proteins in human cataractous lenses. In the present study, the ability of early stage (type II) and advanced (type IV) nuclear cataractous lens....... formation and not DMPO-OOH degradation. The metal ion chelator, diethylenetriaminepentaacetic acid, also inhibited HO. formation, indicating that lenticular metal ions play a key role in HO. formation. Cataractous lens homogenates also stimulated ascorbyl radical production, further suggesting the presence...

  1. Regioselective alkane hydroxylation with a mutant CYP153A6 enzyme

    Science.gov (United States)

    Koch, Daniel J.; Arnold, Frances H.

    2013-01-29

    Cytochrome P450 CYP153A6 from Myobacterium sp. strain HXN1500 was engineered using in-vivo directed evolution to hydroxylate small-chain alkanes regioselectively. Mutant CYP153A6-BMO1 selectively hydroxylates butane and pentane at the terminal carbon to form 1-butanol and 1-pentanol, respectively, at rates greater than wild-type CYP153A6 enzymes. This biocatalyst is highly active for small-chain alkane substrates and the regioselectivity is retained in whole-cell biotransformations.

  2. Effect of strontium addition and chitosan concentration variation on cytotoxicity of chitosan-alginate-carbonate apatite based bone scaffold

    Science.gov (United States)

    Perkasa, Rilis Eka; Umniati, B. Sri; Sunendar, Bambang

    2017-09-01

    Bone scaffold is one of the most important component in bone tissue engineering. Basically, bone scaffold is a biocompatible structure designed to replace broken bone tissue temporarily. Unlike conventional bone replacements, an advanced bone scaffold should be bioactive (e.g: supporting bone growth) and biodegradable as new bone tissue grow, while retain its mechanical properties similarity with bone. It is also possible to add more bioactive substrates to bone scaffold to further support its performance. One of the substrate is strontium, an element that could improve the ability of the bone to repair itself. However, it must be noted that excessive consumption of strontium could lead to toxicity and diseases, such as osteomalacia and hypocalcemia. This research aimed to investigate the effect of strontium addition to the cytotoxic property of chitosan-alginate-carbonate apatite bone scaffold. The amount of strontium added to the bone scaffold was 5% molar of the carbonate apatite content. As a control, bone scaffold without stronsium (0% molar) were also made. The effect of chitosan concentration variation on the cytotoxicity were also observed, where the concentration varies on 1% and 3% w/v of chitosan solution. The results showed an optimum result on bone scaffold sample with 5% molar of strontium and 3% chitosan, where 87.67% cells in the performed MTS-Assay cytotoxicity testing survived. This showed that the use of up to 5% molar addition of strontium and 3% chitosan could enhance the survivability of the cell.

  3. Hydrothermal calcium modification of 316L stainless steel and its apatite forming ability in simulated body fluid.

    Science.gov (United States)

    Valanezahad, Alireza; Ishikawa, Kunio; Tsuru, Kanji; Maruta, Michito; Matsuya, Shigeki

    2011-01-01

    To understand the feasibility of calcium (Ca) modification of type 316L stainless steel (316L SS) surface using hydrothermal treatment, 316L SS plates were treated hydrothermally in calcium chloride (CaCl(2)) solution. X-ray photoelectron spectroscopic analysis revealed that the surface of 316L SS plate was modified with Ca after hydrothermal treatment at 200°C. And the immobilized Ca increased with CaCl(2) concentration. However no Ca-modification was occurred for 316L SS plates treated at 100°C. When Ca-modified 316L SS plate was immersed in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma, low crystalline apatite was precipitated on its surface whereas no precipitate was observed on non Ca-modified 316L SS. The results obtained in the present study indicated that hydrothermal treatment at 200°C in CaCl(2) solution is useful for Ca-modification of 316L SS, and Ca-modification plays important role for apatite precipitation in SBF.

  4. Development of HydroxyCarbonate Apatite on hybrid polymers used in fixed restorations modified by bioactive glass

    Science.gov (United States)

    Georgantzi, B.; Papadopoulou, L.; Zorba, T.; Garefis, P.; Paraskevopoulos, K.; Koidis, P.

    2004-03-01

    The incorporation of a bioactive glass in the structure of hybrid polymers used in dentistry for the construction of fixed prosthetic restorations could induce the expression of bioactivity, leading to the possibility of periodontal tissues reattachment. Hybrid polymer specimens and polymer specimens modified by bioactive glass were prepared and used as control for the surface morphology examination by Scanning Electron Microscopy with associated Dispersive Spectroscopy Analysis (SEM-EDS) and for surface characterization with Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, hybrid polymer specimens modified by bioactive glass were immersed in simulated body fluid (SBF) at 37 °C for different time intervals and were examined by SEM-EDS and FTIR. After 4 days immersion time a dense and continuous apatite layer covered almost the entire modified surface of the specimens. The molar Ca/P ratio reached the value of 1.79. The apatite layer showed a thickness of 1?m and was attached to the substrate, while bioactive glass particles were still present in polymer mass.

  5. Indirect selective laser sintering of an apatite-mullite glass-ceramic for potential use in bone replacement applications.

    Science.gov (United States)

    Goodridge, R D; Dalgarno, K W; Wood, D J

    2006-01-01

    The feasibility of using indirect selective laser sintering (SLS) to produce parts from glass-ceramic materials for bone replacement applications has been investigated. A castable glass based on the system SiO2 x Al2O3 x P2O5 x CaO x CaF2 that crystallizes to a glass-ceramic with apatite and mullite phases was produced, blended with an acrylic binder, and processed by SLS. Green parts with good structural integrity were produced using a wide range of processing conditions, allowing both monolayer and multilayer components to be constructed. Following SLS the parts were post-processed to remove the binder and to crystallize fully the material, evolving the apatite and mullite phases. The parts were heated to 1200 degrees C using a number of different time-temperature profiles, following which the processed material was analysed by differential thermal analysis, X-ray diffraction, and scanning electron microscopy, and tested for flexural strength. An increase in strength was achieved by infiltrating the brown parts with a resorbable phosphate glass, although this altered the crystal phases present in the material.

  6. Control of gene transfer on a DNA-fibronectin-apatite composite layer by the incorporation of carbonate and fluoride ions.

    Science.gov (United States)

    Yazaki, Yushin; Oyane, Ayako; Sogo, Yu; Ito, Atsuo; Yamazaki, Atsushi; Tsurushima, Hideo

    2011-07-01

    Gene transfer techniques are useful tools for controlling cell behavior, such as proliferation and differentiation. We have recently developed an efficient area-specific gene transfer system using a DNA-fibronectin-apatite composite layer (DF-Ap layer). In this system, partial dissolution of the composite layer is likely to be a crucial step for gene transfer. In the present study, layer solubility was adjusted by incorporating various contents of carbonate or fluoride ions into the DF-Ap layer via ionic substitution for the apatite crystals. Carbonate ion incorporation increased the solubility of the DF-Ap layer, thereby increasing the efficiency of gene transfer on the layer. In contrast, the incorporation of fluoride ions decreased the solubility of the DF-Ap layer, thereby decreasing the efficiency and delaying the timing of gene transfer on the layer dose-dependently. The present gene transfer system with controllable efficiency and timing would be useful in tissue engineering applications because cell differentiation can be induced effectively by regulating appropriate gene expression with suitable timing. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. 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

  8. CHNTRN: a CHaNnel TRaNsport model for simulating sediment and chemical distribution in a stream/river network

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.

    1983-09-01

    This report presents the development of a CHaNnel TRaNsport model for simulating sediment and chemical distribution in a stream/river network. A particular feature of the model is its capability to deal with the network system that may consist of any number of joined and branched streams/rivers of comparable size. The model employs a numerical method - an integrated compartment method (ICM) - which greatly facilitates the setup of the matrix equation for the discrete field approximating the corresponding continuous field. Most of the possible boundary conditions that may be anticipated in real-world problems are considered. These include junctions, prescribed concentration, prescribed dispersive flux, and prescribed total flux. The model is applied to two case studies: (1) a single river and (2) a five-segment river in a watershed. Results indicate that the model can realistically simulate the behavior of the sediment and chemical variations in a stream/river network. 11 references, 10 figures, 3 tables.

  9. Oxygen activation at the plasma membrane: relation between superoxide and hydroxyl radical production by isolated membranes.

    Science.gov (United States)

    Heyno, Eiri; Mary, Véronique; Schopfer, Peter; Krieger-Liszkay, Anja

    2011-07-01

    Production of reactive oxygen species (hydroxyl radicals, superoxide radicals and hydrogen peroxide) was studied using EPR spin-trapping techniques and specific dyes in isolated plasma membranes from the growing and the non-growing zones of hypocotyls and roots of etiolated soybean seedlings as well as coleoptiles and roots of etiolated maize seedlings. NAD(P)H mediated the production of superoxide in all plasma membrane samples. Hydroxyl radicals were only produced by the membranes of the hypocotyl growing zone when a Fenton catalyst (FeEDTA) was present. By contrast, in membranes from other parts of the seedlings a low rate of spontaneous hydroxyl radical formation was observed due to the presence of small amounts of tightly bound peroxidase. It is concluded that apoplastic hydroxyl radical generation depends fully, or for the most part, on peroxidase localized in the cell wall. In soybean plasma membranes from the growing zone of the hypocotyl pharmacological tests showed that the superoxide production could potentially be attributed to the action of at least two enzymes, an NADPH oxidase and, in the presence of menadione, a quinone reductase.

  10. Glutathione conjugation of busulfan produces a hydroxyl radical-trapping dehydroalanine metabolite.

    Science.gov (United States)

    Peer, Cody J; Younis, Islam R; Leonard, Stephen S; Gannett, Peter M; Minarchick, Valerie C; Kenyon, Allison J; Rojanasakul, Yon; Callery, Patrick S

    2012-12-01

    The Phase 2 drug metabolism of busulfan yields a glutathione conjugate that undergoes a β-elimination reaction. The elimination product is an electrophilic metabolite that is a dehydroalanine-containing tripeptide, γ-glutamyldehydroalanylglycine (EdAG). In the process, glutathione lacks thiol-related redox properties and gains a radical scavenging dehydroalanine group. EdAG scavenged hydroxyl radical generated in the Fenton reaction in a concentration-dependent manner was monitored by electron paramagnetic resonance (EPR) spectroscopy. The apparent rate of hydroxyl radical scavenging was in the same range as published values for known antioxidants, including N-acyl dehydroalanines. A captodatively stabilized carbon-centered radical intermediate was spin trapped in the reaction of EdAG with hydroxyl radical. The proposed structure of a stable product in the Fenton reaction with EdAG was consistent with that of a γ-glutamylserylglycyl dimer. Observation of the hydroxyl trapping properties of EdAG suggests that the busulfan metabolite EdAG may contribute to or mitigate redox-related cytotoxicity associated with the therapeutic use of busulfan, and reaffirms indicators that support a role in free radical biology for dehydroalanine-containing peptides and proteins.

  11. Advances in the synthesis mulitmetallic systems: hydroxyl group protection in aryldiamine platinum species

    NARCIS (Netherlands)

    Koten, G. van; Davies, P.J.; Grove, D.M.

    1997-01-01

    A multimetallic system containing three platinum atoms has been synthesized through use of an (aryldiamine)platinum complex with a protected hydroxyl group which, after deprotection, is coupled with the trisubstituted aryl molecule 1,3,5-tris(chlorocarbonyl)benzene that provides the core moiety. The

  12. Hydroxylated fullerenes inhibit neutrophil function in fathead minnow (Pimephales promelas Rafinesque, 1820).

    Science.gov (United States)

    Jovanović, Boris; Anastasova, Lora; Rowe, Eric W; Palić, Dušan

    2011-01-25

    Hydroxylated fullerenes act as potent inhibitors of cytochrome P450-dependent monooxygenases, and are reported to be very strong antioxidants quenching reactive oxygen species (ROS) production. Effects of nanosized hydroxylated fullerenes on fish neutrophil function and immune gene transcription was investigated using fathead minnow (Pimephales promelas). Neutrophil function assays were used to determine the effects of fullerene exposure in vitro and in vivo on oxidative burst, degranulation and extracellular trap (NETs) release, and the innate immune gene transcription was determined with quantitative PCR (qPCR). Application of fullerenes (0.2-200 microgmL(-1)in vitro) caused concentration dependent inhibition of oxidative burst and suppressed the release of NETs and degranulation of primary granules (up to 70, 40, and 50% reduction in activity compared to non-treated control, respectively). Transcription of interleukin 11 and myeloperoxidase genes was significantly increased and transcription of elastase 2 gene was significantly decreased in fish exposed to hydroxylated fullerenes for 48h in vivo (12 and 3 fold increase, and 5 fold decrease, respectively). Observed changes in gene transcription and neutrophil function indicate potential for hydroxylated fullerenes to interfere with the evolutionary conserved innate immune system responses and encourages the use of fish models in studies of nanoparticle immunotoxicity. 2010 Elsevier B.V. All rights reserved.

  13. Prediction of hydroxyl concentrations in cement pore water using a numerical cement hydration model

    NARCIS (Netherlands)

    van Eijk, R.J.; Brouwers, Jos

    2000-01-01

    In this paper, a 3D numerical cement hydration model is used for predicting alkali and hydroxyl concentrations in cement pore water. First, this numerical model is calibrated for Dutch cement employing both chemical shrinkage and calorimetric experiments. Secondly, the strength development of some

  14. Biological production of hydroxylated aromatics : Optimization strategies for Pseudomonas putida S12

    NARCIS (Netherlands)

    Verhoef, A.

    2010-01-01

    To replace environmentally unfriendly petrochemical production processes, the demand for bio-based production of organic chemicals is increasing. This thesis focuses on the biological production of hydroxylated aromatics from renewable substrates by engineered P. putida S12 including several cases

  15. Mechanism of the N-Hydroxylation of Primary and Secondary Amines by Cytochrome P450

    DEFF Research Database (Denmark)

    Seger, Signe T.; Rydberg, Patrik; Olsen, Lars

    2015-01-01

    Cytochrome P450 enzymes (CYPs) metabolize alkyl- and arylamines, generating several different products. For the primary and secondary amines, some of these reactions result in hydroxylated amines, which may be toxic. Thus, when designing new drugs containing amine groups, it is important to be able...

  16. Glutathione--hydroxyl radical interaction: a theoretical study on radical recognition process.

    Directory of Open Access Journals (Sweden)

    Béla Fiser

    Full Text Available Non-reactive, comparative (2 × 1.2 μs molecular dynamics simulations were carried out to characterize the interactions between glutathione (GSH, host molecule and hydroxyl radical (OH(•, guest molecule. From this analysis, two distinct steps were identified in the recognition process of hydroxyl radical by glutathione: catching and steering, based on the interactions between the host-guest molecules. Over 78% of all interactions are related to the catching mechanism via complex formation between anionic carboxyl groups and the OH radical, hence both terminal residues of GSH serve as recognition sites. The glycine residue has an additional role in the recognition of OH radical, namely the steering. The flexibility of the Gly residue enables the formation of further interactions of other parts of glutathione (e.g. thiol, α- and β-carbons with the lone electron pair of the hydroxyl radical. Moreover, quantum chemical calculations were carried out on selected GSH/OH(• complexes and on appropriate GSH conformers to describe the energy profile of the recognition process. The relative enthalpy and the free energy changes of the radical recognition of the strongest complexes varied from -42.4 to -27.8 kJ/mol and from -21.3 to 9.8 kJ/mol, respectively. These complexes, containing two or more intermolecular interactions, would be the starting configurations for the hydrogen atom migration to quench the hydroxyl radical via different reaction channels.

  17. Environmentally persistent free radicals (EPFRs)-2. Are free hydroxyl radicals generated in aqueous solutions?

    Science.gov (United States)

    Khachatryan, Lavrent; Dellinger, Barry

    2011-11-01

    A chemical spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), in conjunction with electron paramagnetic resonance (EPR) spectroscopy was employed to measure the production of hydroxyl radical (·OH) in aqueous suspensions of 5% Cu(II)O/silica (3.9% Cu) particles containing environmentally persistent free radicals (EPFRs) of 2-monochlorophenol (2-MCP). The results indicate: (1) a significant differences in accumulated DMPO-OH adducts between EPFR containing particles and non-EPFR control samples, (2) a strong correlation between the concentration of DMPO-OH adducts and EPFRs per gram of particles, and (3) a slow, constant growth of DMPO-OH concentration over a period of days in solution containing 50 μg/mL EPFRs particles + DMPO (150 mM) + reagent balanced by 200 μL phosphate buffered (pH = 7.4) saline. However, failure to form secondary radicals using standard scavengers, such as ethanol, dimethylsulfoxide, sodium formate, and sodium azide, suggests free hydroxyl radicals may not have been generated in solution. This suggests surface-bound, rather than free, hydroxyl radicals were generated by a surface catalyzed-redox cycle involving both the EPFRs and Cu(II)O. Toxicological studies clearly indicate these bound free radicals promote various types of cardiovascular and pulmonary disease normally attributed to unbound free radicals; however, the exact chemical mechanism deserves further study in light of the implication of formation of bound, rather than free, hydroxyl radicals.

  18. Fetal exposure to PCBs and their hydroxylated metabolites in a Dutch cohort

    NARCIS (Netherlands)

    Soechitram, S.D.; Athanasiadou, M.; Hovander, L.; Bergman, A.; Sauer, P. J. J.

    2004-01-01

    Polychlorinated biphenyls (PCBs) are still the most abundant pollutants in wildlife and humans. Hydroxylated PCB metabolites (OH-PCBs) are known to be formed in humans and wildlife. Studies in animals show that these metabolites cause endocrine-related toxicity. The health effects in humans have not

  19. In Vivo Cell Wall Loosening by Hydroxyl Radicals during Cress Seed Germination and Elongation Growth

    NARCIS (Netherlands)

    Muller, K.; Linkies, A.; Vreeburg, R.A.M.; Fry, S.C.; Krieger-Liszkay, A.; Leubner-Metzger, G.

    2009-01-01

    Loosening of cell walls is an important developmental process in key stages of the plant life cycle, including seed germination, elongation growth, and fruit ripening. Here, we report direct in vivo evidence for hydroxyl radical (·OH)-mediated cell wall loosening during plant seed germination and

  20. Environmentally Persistent Free Radicals (EPFRs) - 2. Are Free Hydroxyl Radicals Generated in Aqueous Solutions?

    Science.gov (United States)

    Khachatryan, Lavrent

    2011-01-01

    A chemical spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), in conjunction with electron paramagnetic resonance (EPR) spectroscopy was employed to measure the production of hydroxyl radical (.OH) in aqueous suspensions of 5% Cu(II)O/silica (3.9% Cu) particles containing environmentally persistent free radicals (EPFRs) of 2-monochlorophenol (2-MCP). The results indicate: 1) a significant differences in accumulated DMPO-OH adducts between EPFR containing particles and non-EPFR control samples, 2) a strong correlation between the concentration of DMPO-OH adducts and EPFRs per gram of particles, and 3) a slow, constant growth of DMPO-OH concentration over a period of days in solution containing 50 μg/ml EPFRs particles + DMPO (150 mM) + reagent balanced by 200 μl phosphate buffered (pH = 7.4) saline. However, failure to form secondary radicals using standard scavengers, such as ethanol, dimethylsulfoxide, sodium formate, and sodium azide, suggests free hydroxyl radicals may not have been generated in solution. This suggests surface-bound, rather than free, hydroxyl radicals were generated by a surface catalyzed-redox cycle involving both the EPFRs and Cu(II)O. Toxicological studies clearly indicate these bound free radicals promote various types of cardiovascular and pulmonary disease normally attributed to unbound free radicals; however, the exact chemical mechanism deserves further study in light of the implication of formation of bound, rather than free, hydroxyl radicals. PMID:21942783