WorldWideScience

Sample records for stable fluoride complexes

  1. Fluoride complexation of rutherfordium (Rf, element 104)

    International Nuclear Information System (INIS)

    Strub, E.; Kratz, J.V.; Kronenberg, A.; Naehler, A.; Thoerle, P.; Zauner, S.; Bruechle, W.; Jaeger, E.; Schaedel, M.; Schausten, B.; Schimpf, E.; Zongwei, L.; Kirbach, U.; Schumann, D.; Jost, D.; Tuerler, A.; Asai, M.; Nagame, Y.; Sakama, M.; Tsukada, K.; Gaeggeler, H.W.; Glatz, J.P.

    2000-01-01

    The fluoride complexation of the group-4 elements Zr, Hf and Rf, and of the pseudo-homolog Th, has been investigated in mixed HNO 3 /HF solutions by studying K d values on both cation exchange resins (CIX) and anion exchange resins (AIX) using the automated rapid chemistry apparatus ARCA. On the CIX, the four elements are strongly retained as cations below 10 -3 M HF. For Zr and Hf, the decrease of the K d values due to the formation of fluoride complexes occurs between 10 -3 M HF and 10 -2 M HF. For Rf and Th, this decrease is observed at one order of magnitude higher HF concentrations. On the AIX, for Zr and Hf, a rise of the K d values due to the formation of anionic fluoride complexes is observed between 10 -3 M HF and 10 -2 M HF, i.e. in the same range of HF concentrations where the decrease of the K d values on the CIX is observed, yielding a consistent picture. For Rf and Th, on the AIX, no rise of the K d values is observed even if the HF concentration is increased up to 1 M. By varying the concentration of the counter ion NO 3 - which is competing for the binding sites on the AIX resin, it could be shown, nevertheless, that Rf does form anionic fluoride complexes. Apparently, there is a more specific competition of NO 3 - with respect to [RfF x ] (x-4)- than with [ZrF y ] (y-4)- and [HfF z ] (z-4)- . (orig.)

  2. Hydrothermal fluoride and chloride complexation of indium: an EXAFS study

    Science.gov (United States)

    Loges, Anselm; Testemale, Denis; Huotari, Simo; Honkanen, Ari-Pekka; Potapkin, Vasily; Wagner, Thomas

    2017-04-01

    Indium (In) is one of the geochemically lesser studied ore metals, and the factors that control the hydrothermal transport and deposition are largely unknown. It has no ore deposits of its own and is commonly mined as a by-product of Zn ores, and there are very few minerals that contain In as an essential structural component. Recently, industrial application of In in touch screen devices has drastically increased demand, which is projected to exceed supply from the current sources in the near future. Since the most relevant In sources are hydrothermal sphalerite ores and to a lesser extent hydrothermal greisen-type deposits in evolved granitic plutons, the aqueous geochemistry of In is of particular interest for understanding its ore forming processes. As a first step towards a comprehensive model for hydrothermal In solubility and speciation, we have studied In speciation in fluoride and chloride bearing solutions at 30-400˚ C and 500 bar using X-Ray Absorption Spectroscopy (XAS) measurements. The experiments were conducted in a unique hydrothermal autoclave setup at beamline BM30B-FAME at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. Our results show that the complexation of In changes dramatically between 30 and 400˚ C. Below ca. 200˚ C, fluoride complexes are the most stable ones, but they break down at higher temperatures. Chloride complexes on the other hand become increasingly stable with increasing temperature. This behavior has interesting consequences for natural ore forming systems. In Cl-rich systems (e.g. massive sulfide ores formed in sea floor environments), cooling can be an effective precipitating mechanism. In F-rich systems, fluoride complexation can extend In mobility to low temperatures and In will only precipitate when F is effectively removed from the fluid, e.g. by mixing with a Ca-rich fluid and precipitation of fluorite (CaF2) as is commonly observed in skarn or greisen-type deposits. Due to In complexing with

  3. Complexation of Neptunium(V) with Fluoride at Elevated Temperatures

    International Nuclear Information System (INIS)

    Rao, Linfeng; Tian, Guoxin; Xia, Yuanxian; Friese, Judah I.

    2008-01-01

    Complexation of neptunium(V) with fluoride at elevated temperatures was studied by spectrophotometry and microcalorimetry. Two successive complexes, NpO 2 F(aq) and NpO 2 F 2 - , were identified by spectrophotometry in the temperature range of 10-70 C. Thermodynamic parameters, including the equilibrium constants and enthalpy of complexation between Np(V) and fluoride at 10-70 C were determined. Results show that the complexation of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature - a two-fold increase in the stability constants of NpO 2 F(aq) and more than five-fold increase in the stability constants of NpO 2 F 2 - as the temperature is increased from 10 to 70 C.

  4. Metathesis synthesis and characterization of complex metal fluoride ...

    Indian Academy of Sciences (India)

    Administrator

    V MANIVANNAN*, P PARHI and JONATHAN W KRAMER. Department of Mechanical Engineering, Campus Delivery 1374, Colorado State University, Fort Collins,. CO 80523, USA. MS received 30 April 2008. Abstract. Metathesis synthesis of complex metal fluorides using mechanochemical activation has been reported.

  5. Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides.

    Science.gov (United States)

    Rehmer, Alexander; Scheurell, Kerstin; Scholz, Gudrun; Kemnitz, Erhard

    2017-11-02

    The fluorolytic sol-gel synthesis for binary metal fluorides (AlF₃, CaF₂, MgF₂) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF₅, Ca₂AlF₇, LiMgAlF₆). The formation and crystallization of nanoscopic ternary CaAlF₅ and Ca₂AlF₇ sols in ethanol were studied by 19 F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron microscopy (TEM). The crystalline phases of the annealed CaAlF₅, Ca₂AlF₇, and LiMgAlF₆ xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD) and 19 F solid state NMR spectroscopy. The thermal behavior of un-annealed nanoscopic ternary and quaternary metal fluoride xerogels was ascertained by thermal analysis (TG/DTA). The obtained crystalline phases of CaAlF₅ and Ca₂AlF₇ derived from non-aqueous sol-gel process were compared to crystalline phases from the literature. The corresponding nanoscopic complex metal fluoride could provide a new approach in ceramic and luminescence applications.

  6. Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides

    Directory of Open Access Journals (Sweden)

    Alexander Rehmer

    2017-11-01

    Full Text Available The fluorolytic sol-gel synthesis for binary metal fluorides (AlF3, CaF2, MgF2 has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF5, Ca2AlF7, LiMgAlF6. The formation and crystallization of nanoscopic ternary CaAlF5 and Ca2AlF7 sols in ethanol were studied by 19F liquid and solid state NMR (nuclear magnetic resonance spectroscopy, as well as transmission electron microscopy (TEM. The crystalline phases of the annealed CaAlF5, Ca2AlF7, and LiMgAlF6 xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD and 19F solid state NMR spectroscopy. The thermal behavior of un-annealed nanoscopic ternary and quaternary metal fluoride xerogels was ascertained by thermal analysis (TG/DTA. The obtained crystalline phases of CaAlF5 and Ca2AlF7 derived from non-aqueous sol-gel process were compared to crystalline phases from the literature. The corresponding nanoscopic complex metal fluoride could provide a new approach in ceramic and luminescence applications.

  7. Complex terbium fluoride, Tb(TbF5)3

    International Nuclear Information System (INIS)

    Kiselev, Yu.M.; Goryachenkov, S.A.; Korobov, M.V.; Nikulin, V.V.

    1985-01-01

    A method for preparation of complex terbium fluoride for further utilization of this compound as a source of molecular beams of fluorine is presented. Individuality of the compound is stated by means of the X-ray phase analysis. The molecular beam is generated during 5 hours through a hole 0.03 cm in diameter in the range of 663-765 K. Values of fluorine concentrations in the beam depending on temperature are presented

  8. COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

    Science.gov (United States)

    Seaborg, G.T.

    1960-08-01

    A method is given for precipitating alkali metal plutonium fluorides. such as KPuF/sub 5/, KPu/sub 2/F/sub 9/, NaPuF/sub 5/, and RbPuF/sub 5/, from an aqueous plutonium(IV) solution by adding hydrogen fluoride and alkali-metal- fluoride.

  9. Alkali metal cation complexation and solvent interactions by robust chromium(III) fluoride complexes

    DEFF Research Database (Denmark)

    Birk, T.; Magnussen, M.J.; Piligkos, Stergios

    2010-01-01

    Interaction of robust chromium(III) fluoride complexes with sodium or lithium cations in solution lead to hypsochromic spectral shifts of increasing magnitude along the series: trans-[CrF2(py)(4)](+), mer-[CrF3(terpy)], and fac-[CrF3(Me(3)tacn)]. Crystalline products isolated from solution exhibi...

  10. Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power.

    Science.gov (United States)

    Pfeifer, Lukas; Engle, Keary M; Pidgeon, George W; Sparkes, Hazel A; Thompson, Amber L; Brown, John M; Gouverneur, Véronique

    2016-10-04

    Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5'-fluoro-5'-deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-F bond from F - . Further understanding of the effect of hydrogen bonding on the structure and reactivity of complexed fluoride is therefore important for catalysis and numerous other applications, such as anion supramolecular chemistry. Herein we disclose a detailed study examining the structure of 18 novel urea-fluoride complexes in the solid state, by X-ray and neutron diffraction, and in solution phase and explore the reactivity of these complexes as a fluoride source in S N 2 chemistry. Experimental data show that the structure, coordination strength, and reactivity of the urea-fluoride complexes are tunable by modifying substituents on the urea receptor. Hammett analysis of aryl groups on the urea indicates that fluoride binding is dependent on σ p and σ m parameters with stronger binding being observed for electron-deficient urea ligands. For the first time, defined urea-fluoride complexes are used as fluoride-binding reagents for the nucleophilic substitution of a model alkyl bromide. The reaction is slower in comparison with known alcohol-fluoride complexes, but S N 2 is largely favored over E2, at a ratio surpassing all hydrogen-bonded complexes documented in the literature for the model alkyl bromide employed. Increased second-order rate constants at higher dilution support the hypothesis that the reactive species is a 1:1 urea-fluoride complex of type [UF] - (U = urea) resulting from partial dissociation of the parent compound [U 2 F] - . The dissociation processes can be quantified through a combination of UV and NMR assays, including DOSY and HOESY analyses that illuminate the complexation state and H-bonding in solution.

  11. INTERACTION OF FLUORIDE COMPLEXES DERIVED FROM GLASS-IONOMER CEMENTS WITH HYDROXYAPATITE

    Directory of Open Access Journals (Sweden)

    Lewis S. M.

    2013-09-01

    Full Text Available A study has been undertaken of the interaction of complexed fluoride extracted from glass-ionomer dental cements with synthetic hydroxyapatite powder. Extracts were prepared from two commercial glass-ionomers (Fuji IX and ChemFlex under both neutral and acidic conditions. They were analysed by ICP-OES and by fluoride-ion selective electrode with and without added TISAB to decomplex the fluoride. The pH of the acid extracts was 4, conditions under which fluoride complexes with protons as HF or HF2-, it also complexes with aluminium, which was found to be present in higher amounts in the acid extracts. Fluoride was found to be almost completely complexed in acid extracts, but not in neutral extracts, which contained free fluoride ions. Exposure of these extracts to synthetic hydroxyapatite powder showed that fluoride was taken up rapidly (within 5 minutes, whether or not it was complexed. SEM (EDAX study of recovered hydroxyapatite showed only minute traces of aluminium taken up under all conditions. This showed that aluminium interacts hardly at all with hydroxyapatite, and hence is probably not involved in the remineralisation process.

  12. Determination of the stability constants of a number of metal fluoride complexes and their rates of formation

    International Nuclear Information System (INIS)

    Hammer, R.R.

    1979-08-01

    The stability constants of the fluoride complexes of Al +3 , H 3 BO 3 , Cr +3 , Cr +6 , Fe +3 , Gd +3 , Nb +5 , UO 2 +2 , and Zr +4 were determined in 0.96 and 2.88 M HNO 3 solutions in the temperature range 25 to 60 0 C with a fluoride specific ion electrode. These data can be used to calculate the concentration of chemical species in solution and will be used to correlate solution properties with solution composition. The solubilities of some fluoride precipitates were also measured in nitric acid solutions. The rates of formation of the fluoborates, aluminum fluoride, and zirconium fluoride complexes were measured with a fluoride specific ion electrode at 25, 35, and 45 0 C. The rates of formation of all complexes, except BF 4 - , AlF +2 , and a fluoride complex with aluminum containing more than three fluorides associated with it, were too fast to measure with the instrumentation used

  13. Metal Fluoride Complexes of Na,K-ATPase

    Science.gov (United States)

    Cornelius, Flemming; Mahmmoud, Yasser A.; Toyoshima, Chikashi

    2011-01-01

    The Na,K-ATPase belongs to the P-type ATPase family of primary active cation pumps. Metal fluorides like magnesium-, beryllium-, and aluminum fluoride act as phosphate analogues and inhibit P-type ATPases by interacting with the phosphorylation site, stabilizing conformations that are analogous to specific phosphoenzyme intermediates. Cardiotonic steroids like ouabain used in the treatment of congestive heart failure and arrhythmias specifically inhibit the Na,K-ATPase, and the detailed structure of the highly conserved binding site has recently been described by the crystal structure of the shark Na,K-ATPase in a state analogous to E2·2K+·Pi with ouabain bound with apparently low affinity (1). In the present work inhibition, and subsequent reactivation by high Na+, after treatment of shark Na,K-ATPase with various metal fluorides are characterized. Half-maximal inhibition of Na,K-ATPase activity by metal fluorides is in the micromolar range. The binding of cardiotonic steroids to the metal fluoride-stabilized enzyme forms was investigated using the fluorescent ouabain derivative 9-anthroyl ouabain and compared with binding to phosphorylated enzyme. The fastest binding was to the Be-fluoride stabilized enzyme suggesting a preformed ouabain binding cavity, in accord with results for Ca-ATPase where Be-fluoride stabilizes the E2-P ground state with an open luminal ion access pathway, which in Na,K-ATPase could be a passage for ouabain. The Be-fluoride stabilized enzyme conformation closely resembles the E2-P ground state according to proteinase K cleavage. Ouabain, but not its aglycone ouabagenin, prevented reactivation of this metal fluoride form by high Na+ demonstrating the pivotal role of the sugar moiety in closing the extracellular cation pathway. PMID:21708939

  14. Thorium (4) fluoride complexes in molten iodides and bromides of alkali metals

    International Nuclear Information System (INIS)

    Smirnov, M.V.; Kudyakov, V.Ya.; Shishkin, V.Yu.

    1977-01-01

    The composition and conventional stability constant of fluoride complex formed by tetravalent thorium have been calculated on the basis of measurement of the e.m.f. of galvanic cells, in relation to the temperature and concentration of fluorides in mixed fluoride-bromide and fluoride-iodide melts. It has been established that at elevated temperatures Th(IV) forms anion complexes whose average number of ligands m is not a whole number, varies with the temperature and concentration of the fluorides, and ranges from 6.5 to 5.9. The conventional stability constants of the complexes ThF 6 2- . ThF 7 3- are determined, as well as the variations in the Gibbs energy of reactions of their formation. It is shown that the enthalpies of the reactions of formation of these complexes become more negative with an increase in the difference of the radii of the fluoride anion and the chloride, bromide or iodide anion displaced by it from the corresponding thorium grouping in a pure chloride, bromide or iodide melt

  15. Efficient SN2 fluorination of primary and secondary alkyl bromides by copper(I) fluoride complexes

    KAUST Repository

    Liu, Yanpin

    2013-11-11

    Copper(I) fluoride complexes ligated by phenanthroline derivatives have been synthesized and structurally characterized by X-ray crystallography. These complexes adopt as either ionic or neutral forms in the solid state, depending on the steric bulkiness of the substituent groups on the phenanthroline ligands. These complexes react with primary and secondary alkyl bromides to produce the corresponding alkyl fluorides in modest to good yields. This new method is compatible with a variety of important functional groups such as ether, thioether, amide, nitrile, methoxyl, hydroxyl, ketone, ester, and heterocycle moieties. © 2013 American Chemical Society.

  16. Ammonium boranes for the selective complexation of cyanide or fluoride ions in water.

    Science.gov (United States)

    Hudnall, Todd W; Gabbaï, François P

    2007-10-03

    With the recognition of aqueous fluoride and cyanide ions as an objective, we have investigated the anion binding properties of two isomeric ammonium boranes, namely [p-(Mes2B)C6H4(NMe3)]+ ([1]+) and [o-(Mes2B)C6H4(NMe3)]+ ([2]+). These cationic boranes, which could be obtained by reaction of the known 4- and 2-dimesitylboryl-N,N-dimethylaniline with MeOTf, have been investigated both experimentally and computationally. They both react with fluoride and cyanide ions in organic solvents to afford the corresponding fluoroborate/ or cyanoborate/ammonium zwitterions 1F, 1CN, 2F, and 2CN. In aqueous solution, however, these cationic boranes behave as remarkably selective receptors. Indeed, [1]+ only complexes cyanide ions while [2]+ only complexes fluoride ions. In H2O/DMSO 60:40 vol (HEPES 6 mM, pH 7), the cyanide binding constant of [1]+ and the fluoride binding constant of [2]+ are respectively equal to 3.9 (+/-0.1) x 108 and 910 (+/-50) M-1. Structural and computational studies indicate that both steric and electronic effects contribute to the unusual selectivity displayed by these cationic boranes. Owing to favorable Coulombic effects, the para-derivative [1]+ has a very high affinity for cyanide; yet these effects are not sufficiently intense to allow complexation of the more efficiently hydrated and less basic fluoride anion. In the case of the ortho-derivative [2]+, the proximity of the ammonium moiety leads to an increase in the Lewis acidity of the boron center thus making fluoride binding possible. However, steric effects prevent cyanide coordination to the boron center of [2]+. Finally, cation [1]+ and [2]+ bind their dedicated anions reversibly and show a negligible response in the presence of other common anions including Cl-, Br-, I-, NO3-, OAc-, H2PO4-, and HSO4-.

  17. Theoretical study on the complexation of bambus[6]uril with the fluoride anion

    Czech Academy of Sciences Publication Activity Database

    Toman, Petr; Makrlík, E.; Vaňura, P.

    2012-01-01

    Roč. 989, 1 June (2012), s. 97-99 ISSN 2210-271X R&D Projects: GA ČR(CZ) GAP205/10/2280 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : bambus[6]uril * fluoride anion * complexation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.139, year: 2012

  18. Copper-Mediated Fluorination of Arylboronate Esters. Identification of a Copper(III) Fluoride Complex

    Science.gov (United States)

    Fier, Patrick S.; Luo, Jingwei; Hartwig, John F.

    2013-01-01

    A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through aryl-boronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III) followed by rate-limiting transmetallation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS. PMID:23384209

  19. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    , the tuples of cohomology classes on a compact, complex manifold, corresponding to the Chern classes of a complex vector bundle of stable rank. This classification becomes more effective on generalized flag manifolds, where the Lie ...

  20. Electrochemistry of the Oxofluoro Complexes of Boron in Fluoride Melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Bukatova, G.A.; Polyakov, E.G.

    1997-01-01

    Electrochemical behavior of oxofluoro complexes of boron, synthesized both in situ in FLINAK melt and added into the melt as Na3B3O3F6 compound, was by linear voltammetry within the range of 570-750 oC. It was shown that in lower part of this range the electrochemical reduction of BOF2- complexes...... energy of 61.6 kJ/mol. Study of the thermal stability of boron containing oxofluoro melts showed that O/B ratio changes in time due to evaporation of BF3. As a result borate complexes emerge in the melt alongside with oxofluoro ones....

  1. Redox electrochemistry of europium fluoride complexes in an equimolar NaCl-KCl melt

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, S.A., E-mail: kuznet@chemy.kolasc.net.ru [Institute of Chemistry, Kola Science Centre RAS, 26 Akademgorodok., 184209 Apatity, Murmansk region (Russian Federation); Gaune-Escard, M. [Ecole Polytechnique, Mecanique Energetique, Technopole de Chateau Gombert, 5 rue Enrico Fermi, 13453 Marseille Cedex 13 (France)

    2011-07-15

    The electrochemical behavior of europium fluoride complexes was studied by different electrochemical methods at a glassy carbon electrode in the temperature range 973-1100 K in the NaCl-KCl melt. The diffusion coefficients of Eu(III) and Eu(II) were determined by linear sweep voltammetry. The standard rate constants of charge transfer for the Eu(III)/Eu(II) redox couple were found on the base cyclic voltammetry, impedance spectroscopy and chronoamperometry data. The formal standard redox potentials E{sub Eu(III)/Eu(II)}{sup *} were obtained by linear sweep and cyclic voltammetry. The electrochemical behavior of europium fluoride and europium chloride complexes in NaCl-KCl melt was compared and discussed in connection with the strength and stability of these complexes. It was shown that the formation of stronger fluoride complexes reduced values of diffusion coefficients, standard rate constants for charge transfer of the Eu(III)/Eu(II) redox couple and shifted the formal standard redox potentials to the more electronegative values.

  2. Effect of fluoridated casein phospopeptide-amorphous-calcium phosphate complex, chlorhexidine fluoride mouthwash on shear bond strength of orthodontic brackets: A comparative in vitro study

    Directory of Open Access Journals (Sweden)

    C A Abdul Shahariyar

    2016-01-01

    Full Text Available Objective: The aim of the current study was to determine the effects of casein phosphopeptide amorphous calcium-phosphate (CPP-ACP complex, chlorhexidine fluoride mouthwash on shear bond strengths (SBSs of orthodontic brackets. Materials and Methods: About sixty extracted healthy human premolar teeth with intact buccal enamel were divided into two equal groups to which brackets were bonded using self-etching primers (SEPs and conventional means respectively. These were further equally divided into three subgroups - (1 control (2 CPP-ACP (3 chlorhexidine fluoride mouthwash. The SBSs were then measured using a universal testing machine. Results: SBS of the conventional group was significantly higher than the self-etching group. The intragroup differences were statistically insignificant. Conclusion: CPP-ACP, chlorhexidine fluoride mouthwash did not adversely affect SBS of orthodontic brackets irrespective of the method of conditioning. Brackets bonded with conventional technique showed greater bond strengths as compared to those bonded with SEP.

  3. Optical Sensing of Fluoride Through a Self-Organized Fluorescent Ensemble of Quinizarin-Al(III) Complex.

    Science.gov (United States)

    Adurty, Sunil; Karnam, Lohith; Chittor, Sundaresan Neelakantan; Belliraj, Siva Kumar

    2016-11-01

    A one-pot, cost-effective system for sensing fluoride ions using quinizarin as a novel chromophore is reported. Quinizarin complexes with Al(III) to form a self-organized turn-on fluorescence system in methanol. In the presence of fluoride ions, this system undergoes a subsequent ligand swap reaction with the fluoride ion and consequently the fluorescence turns off, delivering a sensitive route for the estimation of fluoride. This domino effect presents a sensitive and selective reaction system for the detection of fluoride ions in the concentration range 0.5-15 ppm. The study was performed using spectrophotometric and spectrofluorimetric techniques. Various analytical parameters such as pH, equilibration time, ambient temperature, and applicability of the method have been reported along with the study of the associated interfering ions.

  4. Speciation analysis of aluminium and aluminium fluoride complexes by HPIC-UVVIS.

    Science.gov (United States)

    Frankowski, Marcin; Zioła-Frankowska, Anetta

    2010-10-15

    The study presents a new analytical method for speciation analysis in fractionation of aluminium fluoride complexes and free Al(3+) in soil samples. Aluminium speciation was studied in model solutions and soil extract samples by means of high performance ion chromatography (HPIC) with UV-VIS detection using post-column reaction with tiron for the separation and detection of aluminium fluoride complex and Al(3+) forms during one analysis. The paper presents particular stages of the chromatographic process optimization involving selecting the appropriate eluent strength, type of elution or concentration and quantity of derivatization reagent. HPIC was performed on a bifunctional analytical column Dionex IonPac CS5A. The use of gradient elution and the eluents A: 1M NH(4)Cl and B: water acidified to pH of eluent phase, enabled full separation of fluoride aluminium forms as AlF(2)(+), AlF(3)(0), AlF(4)(-) (first signal), AlF(2+) (second signal) and form Al(3+) in a single analytical procedure. The proposed new method HPIC-UVVIS was applied successfully in the quantitative and qualitative analysis of soil samples. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. The allosteric transition of GroEL induced by metal fluoride-ADP complexes.

    Science.gov (United States)

    Inobe, Tomonao; Kikushima, Kenji; Makio, Tadashi; Arai, Munehito; Kuwajima, Kunihiro

    2003-05-23

    To understand the mechanism of a functionally important ATP-induced allosteric transition of GroEL, we have studied the effect of a series of metal fluoride-ADP complexes and vanadate-ADP on GroEL by kinetic fluorescence measurement of pyrene-labeled GroEL and by small-angle X-ray scattering measurement of wild-type GroEL. The metal fluorides and vanadate, complexed with ADP, are known to mimic the gamma-phosphate group of ATP, but they differ in geometry and size; it is expected that these compounds will be useful for investigating the strikingly high specificity of GroEL for ATP that enables the induction of the allosteric transition. The kinetic fluorescence measurement revealed that aluminium, beryllium, and gallium ions, when complexed with the fluoride ion and ADP, induced a biphasic fluorescence change of pyrenyl GroEL, while scandium and vanadate ions did not induce any kinetically observed change in fluorescence. The burst phase and the first phase of the fluorescence kinetics were reversible, while the second phase and subsequent changes were irreversible. The dependence of the burst-phase and the first-phase fluorescence changes on the ADP concentration indicated that the burst phase represents non-cooperative nucleotide binding to GroEL, and that the first phase represents the allosteric transition of GroEL. Both the amplitude and the rate constant of the first phase of the fluorescence kinetics were well understood in terms of a kinetic allosteric model, which is a combination of transition state theory and the Monod-Wyman-Changeux allosteric model. From the kinetic allosteric model analysis, the relative free energy of the transition state in the metal fluoride-ADP-induced allosteric transition of GroEL was found to be larger than the corresponding free energy of the ATP-induced allosteric transition by more than 5.5kcal/mol. However, the X-ray scattering measurements indicated that the allosteric state induced by these metal fluoride-ADP complexes is

  6. Ionic liquid and solid HF equivalent amine-poly(hydrogen fluoride) complexes effecting efficient environmentally friendly isobutane-isobutylene alkylation.

    Science.gov (United States)

    Olah, George A; Mathew, Thomas; Goeppert, Alain; Török, Béla; Bucsi, Imre; Li, Xing-Ya; Wang, Qi; Marinez, Eric R; Batamack, Patrice; Aniszfeld, Robert; Prakash, G K Surya

    2005-04-27

    Isoparaffin-olefin alkylation was investigated using liquid as well as solid onium poly(hydrogen fluoride) catalysts. These new immobilized anhydrous HF catalysts contain varied amines and nitrogen-containing polymers as complexing agents. The liquid poly(hydrogen fluoride) complexes of amines are typical ionic liquids, which are convenient media and serve as HF equivalent catalysts with decreased volatility for isoparaffin-olefin alkylation. Polymeric solid amine:poly(hydrogen fluoride) complexes are excellent solid HF equivalents for similar alkylation acid catalysis. Isobutane-isobutylene or 2-butene alkylation gave excellent yields of high octane alkylates (up to RON = 94). Apart from their excellent catalytic performance, the new catalyst systems significantly reduce environmental hazards due to the low volatility of complexed HF. They represent a new, "green" class of catalyst systems for alkylation reactions, maintaining activity of HF while minimizing its environmental hazards.

  7. On the mechanism of phosphoenolpyruvate synthetase (PEPs) and its inhibition by sodium fluoride: potential magnesium and aluminum fluoride complexes of phosphoryl transfer.

    Science.gov (United States)

    McCormick, Nicole E; Jakeman, David L

    2015-06-01

    Phosphoenolpyruvate synthase (PEPs) catalyzes the conversion of pyruvate to phosphoenolpyruvate (PEP) using a two-step mechanism invoking a phosphorylated-His intermediate. Formation of PEP is an initial step in gluconeogenesis, and PEPs is essential for growth of Escherichia coli on 3-carbon sources such as pyruvate. The production of PEPs has also been linked to bacterial virulence and antibiotic resistance. As such, PEPs is of interest as a target for antibiotic development, and initial investigations of PEPs have indicated inhibition by sodium fluoride. Similar inhibition has been observed in a variety of phospho-transfer enzymes through the formation of metal fluoride complexes within the active site. Herein we quantify the inhibitory capacity of sodium fluoride through a coupled spectrophotometric assay. The observed inhibition provides indirect evidence for the formation of a MgF3(-) complex within the enzyme active site and insight into the phospho-transfer mechanism of PEPs. The effect of AlCl3 on PEPs enzyme activity was also assessed and found to decrease substrate binding and turnover.

  8. Molecular Fluoride-Bridged 3d-4f Complexes and Their Magnetic Properties

    DEFF Research Database (Denmark)

    Pedersen, K. S.; Bendix, J.

    2016-01-01

    Fluoride-bridged systems benefit from the redox- and spectroscopic innocence of fluoride, which facilitates spectroscopic characterization and elucidation of their electronic structures. Although fluorine is often thought of as the "nonstick" element par excellence, fluoride-bridging can be utili...

  9. Method of purifying uranium tetrafluoride hydrate and preparing uranium (VI) peroxide hydrate using a fluoride complexing agent

    International Nuclear Information System (INIS)

    Barreiro, A.J.; Lowe, C.M.T.; Lefever, J.A.; Pyman, R.L.

    1983-01-01

    The annual production of phosphate rock, on the order of about 30-40 million tons yearly, represents several million pounds of uranium. The present invention provides a process of purifying uranium tetrafluoride hydrate to produce a uranium (VI) peroxide product meeting 'yellow cake' standards using a double precipitation procedure. A fluoride complexing agent is used in the precipitation

  10. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    In the present paper, we study the classification of stable-rank bundles on some compact complex manifolds. First, we extend ... below the results obtained in this case (see Propositions 4.1–4.3 and Theorems 5.1–5.3 for .... In order to prove the converse inclusion, let (c1,...,cp+1) be a (p + 1)-tuple of coho- mology classes ...

  11. On the classification of complex vector bundles of stable rank

    Indian Academy of Sciences (India)

    a classification of all rank r complex vector bundles on X, for stable rank r ≥ n/2. A few partial answers to this question are known. For instance, a classical result of. Wu asserts that any couple of cohomology classes (c1,c2) ∈ H2(X, Z) × H4(X, Z) coincides with c(E) for a vector bundle E, on a basis X of dimension less than ...

  12. Surface Complexation Modeling of Fluoride Adsorption by Soil and the Role of Dissolved Aluminum on Adsorption

    Science.gov (United States)

    Padhi, S.; Tokunaga, T.

    2017-12-01

    Adsorption of fluoride (F) on soil can control the mobility of F and subsequent contamination of groundwater. Hence, accurate evaluation of adsorption equilibrium is a prerequisite for understanding transport and fate of F in the subsurface. While there have been studies for the adsorption behavior of F with respect to single mineral constituents based on surface complexation models (SCM), F adsorption to natural soil in the presence of complexing agents needs much investigation. We evaluated the adsorption processes of F on a natural granitic soil from Tsukuba, Japan, as a function of initial F concentration, ionic strength, and initial pH. A SCM was developed to model F adsorption behavior. Four possible surface complexation reactions were postulated with and without including dissolved aluminum (Al) and Al-F complex sorption. Decrease in F adsorption with the increase in initial pH was observed in between the initial pH range of 4 to 9, and a decrease in the rate of the reduction of adsorbed F with respect to the increase in the initial pH was observed in the initial pH range of 5 to 7. Ionic strength variation in the range of 0 to 100mM had insignificant effect on F removal. Changes in solution pH were observed by comparing the solution before and after F adsorption experiments. At acidic pH, the solution pH increased, whereas at alkaline pH, the solution pH decreased after equilibrium. The SCM including dissolved Al and the adsorption of Al-F complex can simulate the experimental results quite successfully. Also, including dissolved Al and the adsorption of Al-F complex to the model explained the change in solution pH after F adsorption.

  13. Fluoride and fluoridation.

    Science.gov (United States)

    Smith, G E

    1988-01-01

    To date, many of the ways of controlling tooth decay involve the use of fluorides. Either systemically via fluoridated water and tablets, or, topically, with fluoride-containing toothpaste and mouthrinses. There is now evidence that the prevalence of dental caries is declining in communities with unfluoridated water, as well as in those with fluoridated water. This phenomenon may be related to an increase of fluoride in the food chain; the unintentional ingestion of fluoride-containing dental health products; and the increasing contamination of the total environment with fluoride emissions and solid wastes from many industries. The apparent usefulness of fluoride as a preventive against dental caries does not mean that unnecessary exposure to the element should be tolerated. Fluoride at very low concentrations is phytotoxic and harmful to livestock; and in man, excessive intakes of fluoride over many years may lead to a well-defined disorder--skeletal fluorosis. In addition, a number of recent studies have suggested that fluoride may be genotoxic.

  14. Determination of the Magnetic Structure of Complex anti-Perovskite Fluorides by Neutron Diffraction

    Science.gov (United States)

    Felder, Justin; Yeon, Jeongho; Zur Loye, Hans-Conrad

    An unusual family of anti-perovskite fluorides consisting of complex ions as the A, B, and X building units has been synthesized as single crystals. This family of anti-perovskites provides a unique framework to probe the magnetic properties of transition metals. Presented here is the Fe endmember of the family: [Cu(H2O)4]3[FeF6]2. The iron member exhibits complex magnetic behavior at low temperatures, which has been probed by magnetometry and neutron diffraction experiments. Presented here are the results from the anisotropic magnetometry study as well as the magnetic spin structure as determined by neutron diffraction experiments. The materials presented here represent an interesting class of perovskites that are as-yet unexplored. Given the wide range of properties possible in perovskites and related structures, it is reasonable to expect that further exploration of these materials will reveal many interesting attributes; both chemical and physical. United States Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, Award DE-SC0008664.

  15. Fluoridated Water

    Science.gov (United States)

    ... Genetics Services Directory Cancer Prevention Overview Research Fluoridated Water On This Page What is fluoride, and where is it found? What is water fluoridation? When did water fluoridation begin in the ...

  16. Dissociation of gaseous complex fluorides MMnF3 and MMnF4 (M= Li - Cs)

    International Nuclear Information System (INIS)

    Sidorov, L.N.; Gubarevich, V.D.

    1982-01-01

    Mass spectrometric determination of dissociation enthalpies of gaseous complex fluorides CsMnF 3 and CsMnF 4 into neutral and charged particles is carried out using techniques of isothermal evaporation, electron impact and study of ion-molecular equilibria. As a result formation enthalpy values of CsMnFsub(3 gas) and CsMnFsub(4 gas) at T=298 are obtained, being -285.4 and -359.9 kcal/mol respectively

  17. Application of membrane LaF3 electrode in the determination of stability constants of Uranyl Fluoride complex in solution

    International Nuclear Information System (INIS)

    Muzakky; Iswani GS; Mintolo

    1996-01-01

    A membrane electrode LaF 3 has been applied in the determination of uranyl fluoride complex stability constant in solution. The determination is based on the detection of free F ion in solution as a result of hydrolysis reaction (process) of uranyl ions into the uranyl hydroxide form at low pH. The experiment results showed that there was no effect of ammonium carbonate 2 M titran, flow rate on the electrode response. The F release is optimum at pH 1. The free F ion in solution is calculated from the standard curve at pH 1, after the fluoride concentration at the same pH has been corrected. Using the plot of average number of ligand binding (n) versus minus log of free ligand (-log F) the value of β1 = 4.4, β2 = 7.48, β3=9.73, and β4 = 11.67

  18. Reactivity of paraquat with sodium salicylate: formation of stable complexes.

    Science.gov (United States)

    Dinis-Oliveira, Ricardo Jorge; de Pinho, Paula Guedes; Ferreira, António César Silva; Silva, Artur M S; Afonso, Carlos; Bastos, Maria de Lourdes; Remião, Fernando; Duarte, José Alberto; Carvalho, Félix

    2008-07-30

    Sodium salicylate (NaSAL) has been shown to be a promising antidote for the treatment of paraquat (PQ) poisonings. The modulation of the pro-oxidant and pro-inflammatory pathways, as well as the anti-thrombogenic properties of NaSAL are probably essential features for the healing effects provided by this drug. Nevertheless, a possible direct chemical reactivity between PQ and NaSAL is also a putative pathway to be considered, this hypothesis being the ground of the present study. In accordance, it is shown, for the first time that PQ and NaSAL react immediately in aqueous medium and within 2-3 min in the solid state. Photographs and scanning electron photomicrographs indicated that a new chemical entity is formed when both compounds are mixed. This assumption was corroborated by the evaluation of the melting point, and through several analytical techniques, namely ultraviolet/visible spectroscopy, nuclear magnetic resonance spectroscopy, gas chromatography/mass spectrometry/mass spectrometry (GC/MS/MS), liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry (LC/ESI/MS/MS) and infrared spectroscopy, which revealed that stable charge-transfer complexes are formed when PQ is mixed with NaSAL. LC/ESI/MS/MS allowed obtaining the stoichiometry of the charge-transfer complexes. In order to increase resolution, single value decomposition, acting as a filter, showed that the charge-transfer complexes with m/z 483, 643 and 803 correspond to the pseudo-molecular ions, respectively 1:2, 1:3 and 1:4 (PQ:NaSAL). In conclusion, these results provided a new and important mechanism of action of NaSAL against the toxicity mediated by PQ.

  19. Reactivity of paraquat with sodium salicylate: Formation of stable complexes

    International Nuclear Information System (INIS)

    Dinis-Oliveira, Ricardo Jorge; Guedes de Pinho, Paula; Ferreira, Antonio Cesar Silva; Silva, Artur M.S.; Afonso, Carlos; Bastos, Maria de Lourdes; Remiao, Fernando; Duarte, Jose Alberto; Carvalho, Felix

    2008-01-01

    Sodium salicylate (NaSAL) has been shown to be a promising antidote for the treatment of paraquat (PQ) poisonings. The modulation of the pro-oxidant and pro-inflammatory pathways, as well as the anti-thrombogenic properties of NaSAL are probably essential features for the healing effects provided by this drug. Nevertheless, a possible direct chemical reactivity between PQ and NaSAL is also a putative pathway to be considered, this hypothesis being the ground of the present study. In accordance, it is shown, for the first time that PQ and NaSAL react immediately in aqueous medium and within 2-3 min in the solid state. Photographs and scanning electron photomicrographs indicated that a new chemical entity is formed when both compounds are mixed. This assumption was corroborated by the evaluation of the melting point, and through several analytical techniques, namely ultraviolet/visible spectroscopy, nuclear magnetic resonance spectroscopy, gas chromatography/mass spectrometry/mass spectrometry (GC/MS/MS), liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry (LC/ESI/MS/MS) and infrared spectroscopy, which revealed that stable charge-transfer complexes are formed when PQ is mixed with NaSAL. LC/ESI/MS/MS allowed obtaining the stoichiometry of the charge-transfer complexes. In order to increase resolution, single value decomposition, acting as a filter, showed that the charge-transfer complexes with m/z 483, 643 and 803 correspond to the pseudo-molecular ions, respectively 1:2, 1:3 and 1:4 (PQ:NaSAL). In conclusion, these results provided a new and important mechanism of action of NaSAL against the toxicity mediated by PQ

  20. Metal fluoride complexes of Na,K-ATPase: characterization of fluoride-stabilized phosphoenzyme analogues and their interaction with cardiotonic steroids.

    Science.gov (United States)

    Cornelius, Flemming; Mahmmoud, Yasser A; Toyoshima, Chikashi

    2011-08-26

    The Na,K-ATPase belongs to the P-type ATPase family of primary active cation pumps. Metal fluorides like magnesium-, beryllium-, and aluminum fluoride act as phosphate analogues and inhibit P-type ATPases by interacting with the phosphorylation site, stabilizing conformations that are analogous to specific phosphoenzyme intermediates. Cardiotonic steroids like ouabain used in the treatment of congestive heart failure and arrhythmias specifically inhibit the Na,K-ATPase, and the detailed structure of the highly conserved binding site has recently been described by the crystal structure of the shark Na,K-ATPase in a state analogous to E2·2K(+)·P(i) with ouabain bound with apparently low affinity (1). In the present work inhibition, and subsequent reactivation by high Na(+), after treatment of shark Na,K-ATPase with various metal fluorides are characterized. Half-maximal inhibition of Na,K-ATPase activity by metal fluorides is in the micromolar range. The binding of cardiotonic steroids to the metal fluoride-stabilized enzyme forms was investigated using the fluorescent ouabain derivative 9-anthroyl ouabain and compared with binding to phosphorylated enzyme. The fastest binding was to the Be-fluoride stabilized enzyme suggesting a preformed ouabain binding cavity, in accord with results for Ca-ATPase where Be-fluoride stabilizes the E2-P ground state with an open luminal ion access pathway, which in Na,K-ATPase could be a passage for ouabain. The Be-fluoride stabilized enzyme conformation closely resembles the E2-P ground state according to proteinase K cleavage. Ouabain, but not its aglycone ouabagenin, prevented reactivation of this metal fluoride form by high Na(+) demonstrating the pivotal role of the sugar moiety in closing the extracellular cation pathway.

  1. Investigation of gold fluorides and noble gas complexes by matrix-isolation spectroscopy and quantum-chemical calculations.

    Science.gov (United States)

    Wang, Xuefeng; Andrews, Lester; Willmann, Knut; Brosi, Felix; Riedel, Sebastian

    2012-10-15

    Noble with a difference: Matrix-isolation experiments and quantum-chemical calculations have led to the characterization of two new compounds, namely first open-shell binary gold fluoride, AuF(2), and a NeAuF complex. Moreover, ArAuF, AuF(3), Au(2)F(6), and monomeric AuF(5) have been produced and identified under cryogenic conditions in neon and argon matrices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Microwave spectrum, dipole moment, and internal dynamics of the methyl fluoride-carbonyl sulfide weakly bound complex.

    Science.gov (United States)

    Serafin, Michal M; Peebles, Sean A

    2008-02-21

    Rotational spectra for the normal and four isotopically substituted species of the 1:1 complex between methyl fluoride (H3CF) and carbonyl sulfide (OCS) have been measured using Fourier-transform microwave spectroscopy in the 5-16 GHz frequency region. The observed spectra fit well to a semirigid Watson Hamiltonian, and an analysis of the rotational constants has allowed a structure to be determined for this complex. The dipole moment vectors of the H3CF and OCS monomers are aligned approximately antiparallel with a C...C separation of 3.75(3) A and with an ab plane of symmetry. The values of the Pcc planar moments were found to be considerably different from the expected rigid values for all isotopologues. An estimate of approximately 14.5(50) cm-1 for the internal rotation barrier of the CH3 group with respect to the framework of the complex has been made using the Pcc values for the H3CF-OCS and D3CF-OCS isotopic species. Two structures, very close in energy and approximately related by a 60 degrees rotation about the C3 axis of the methyl fluoride, were identified by ab initio calculations at the MP2/6-311++G(2d,2p) level and provide reasonable agreement with the experimental rotational constants and dipole moment components.

  3. Fluoride and Oral Health.

    Science.gov (United States)

    O'Mullane, D M; Baez, R J; Jones, S; Lennon, M A; Petersen, P E; Rugg-Gunn, A J; Whelton, H; Whitford, G M

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.

  4. Ranking stability and super-stable nodes in complex networks.

    Science.gov (United States)

    Ghoshal, Gourab; Barabási, Albert-László

    2011-07-19

    Pagerank, a network-based diffusion algorithm, has emerged as the leading method to rank web content, ecological species and even scientists. Despite its wide use, it remains unknown how the structure of the network on which it operates affects its performance. Here we show that for random networks the ranking provided by pagerank is sensitive to perturbations in the network topology, making it unreliable for incomplete or noisy systems. In contrast, in scale-free networks we predict analytically the emergence of super-stable nodes whose ranking is exceptionally stable to perturbations. We calculate the dependence of the number of super-stable nodes on network characteristics and demonstrate their presence in real networks, in agreement with the analytical predictions. These results not only deepen our understanding of the interplay between network topology and dynamical processes but also have implications in all areas where ranking has a role, from science to marketing.

  5. Stability constants of the fluoride complexes of actinides in aqueous solution and their correlation with fundamental properties

    International Nuclear Information System (INIS)

    Chaudhuri, N.K.; Sawant, R.M.

    1997-09-01

    Stability constants of the fluoride complexes of the actinides in different oxidation states measured by potentiometric method using fluoride ion selective electrode have been presented. Procedure and precautions required to overcome certain difficulties particular to actinide ions have been discussed. Literature data from various sources have been compiled. In order to have a reasonable comparison the stability constant (β 1 ) values obtained in diverse ionic strength media are converted to thermodynamic stability constant, β 1 0 , using Davies equation (a modification of Debye-Huckel equation). A correlation of the β 1 0 values with the fundamental properties of the actinide ions using various models available in the literature has been attempted. A semiempirical relation recently developed by Brown, Sylva and Ellis (BSE equation) appears to be most suitable. Using the values of ionic radii and best available values of the stability constants of a large number of metal ions from recent compilations a comparative study of the various models or relations available in the literature has been tried. For metal ions in general, the best correlation is obtained with the BSE equation. In an attempt to accommodate the unusual trend in the stability constants of the tetravalent actinides a modification in a parameter of the BSE equation has been proposed. Good agreement between the theoretically calculated and experimentally determined values for actinides in different oxidation states is then obtained in most of the cases. (author)

  6. Fluoridation Basics

    Science.gov (United States)

    ... Water Today The mineral fluoride occurs naturally on earth and is released from rocks into the soil, ... where your state ranks in percent of the population that receives water with fluoride . Cost: Saves Money, ...

  7. Complex cobordism and stable homotopy groups of spheres

    CERN Document Server

    Ravenel, Douglas C

    2003-01-01

    Since the publication of its first edition, this book has served as one of the few available on the classical Adams spectral sequence, and is the best account on the Adams-Novikov spectral sequence. This new edition has been updated in many places, especially the final chapter, which has been completely rewritten with an eye toward future research in the field. It remains the definitive reference on the stable homotopy groups of spheres. The first three chapters introduce the homotopy groups of spheres and take the reader from the classical results in the field though the computational aspects

  8. Pyridinophane platform for stable lanthanide(III) complexation.

    Science.gov (United States)

    Castro, Goretti; Bastida, Rufina; Macías, Alejandro; Pérez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, Laura

    2013-05-20

    A detailed investigation of the solid state and solution structures of lanthanide(III) complexes with the macrocyclic ligand 2,11,20-triaza[3.3.3](2,6)pyridinophane (TPP) is reported. The solid state structures of 14 different Ln(3+) complexes have been determined using X-ray crystallography. The ligand is coordinating to the Ln(3+) ion by using its six nitrogen atoms, while nitrate or triflate anions and water molecules complete the metal coordination environments. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by DFT calculations (TPSSh model) performed in aqueous solution. The structures obtained from these calculations for the complexes with the lightest Ln(3+) ions (La-Sm) are in very good agreement with those determined by the analysis of the Ln(3+)-induced paramagnetic shifts. A structural change occurs across the lanthanide series at Sm(3+); the complexes of the large Ln(3+) ions (La-Nd) are chiral due to the nonplanar conformation of the macrocycle, and present effective C3v symmetries in solution as a consequence of a fast interconversion of two enantiomeric forms with C3 symmetry. The activation free energy for this enantiomerization process, as estimated by using DFT calculations, amounts to 33.0 kJ·mol(-1). The TPP ligand in the complexes of the heaviest Ln(3+) ions (Eu-Lu) presents a half-chair conformation, which results in C(s) symmetries in solution.

  9. Visualization of Fluoride Ions In Vivo Using a Gadolinium(III)-Coumarin Complex-Based Fluorescence/MRI Dual-Modal Probe.

    Science.gov (United States)

    Wang, Yue; Song, Renfeng; Feng, Huan; Guo, Ke; Meng, Qingtao; Chi, Haijun; Zhang, Run; Zhang, Zhiqiang

    2016-12-16

    A new Gadolinium(III)-coumarin complex, DO3A-Gd- CA , was designed and prepared as a dual-modal probe for simultaneous fluorescence and relaxivity responses to fluoride ions (F - ) in aqueous media and mice. DO3A-Gd- CA was designed by using Gd(III) center as an MRI signal output unit and fluoride binding site, and the 4-(diethylamino)-coumarin-3-carboxylic acid ( CA ) as a fluorescence reporter. Upon the addition of fluoride ions to the solution of DO3A-Gd- CA , the liberation of the coordinated CA ligand led to a 5.7-fold fluorescence enhancement and a 75% increase in the longitudinal relaxivity ( r ₁). The fluorescent detection limit for fluoride ions was determined to be 8 μM based on a 3 σ / slope . The desirable features of the proposed DO3A-Gd- CA , such as high sensitivity and specificity, reliability at physiological pH and low cytotoxicity enable its application in visualization of fluoride ion in mice. The successful in vivo imaging indicates that DO3A-Gd- CA could be potentially used in biomedical diagnosis fields.

  10. Rotational spectroscopic studies of C-H · · · F interactions in the vinyl fluoride · · · difluoromethane complex.

    Science.gov (United States)

    Christenholz, Cori L; Obenchain, Daniel A; Peebles, Rebecca A; Peebles, Sean A

    2014-03-06

    Rotational spectra of the normal isotopic species and three (13)C isotopologues of the 1:1 complex between vinyl fluoride (CH2 ═ CHF) and difluoromethane (CH2F2) have been measured using 480 MHz bandwidth chirped-pulse Fourier-transform microwave spectroscopy in the 6.5-20 GHz region. A structure for this dimer has been determined by fitting the moments of inertia of all isotopologues and confirmed by calculation of Kraitchman single isotopic substitution coordinates. The structure is consistent with that determined by ab initio geometry optimization at the MP2/6-311++G(2d,2p) level and has the difluoromethane subunit located on the CHF side of the vinyl fluoride subunit with three C-H · · · F contacts and with the hydrogen atoms of the CH2F2 straddling the vinyl fluoride symmetry plane.

  11. Complex interferometry potential in case of sufficiently stable diagnostic system

    Science.gov (United States)

    Kalal, M.

    2016-06-01

    Classical interferometry is one of the key methods among active optical diagnostics. Its more advanced version, which allows recording and subsequent reconstruction of up to three sets of data using just one data object —a complex interferogram—was developed in the past and became known as complex interferometry. Employing this diagnostics, not only the usual phase shift, but also the amplitude of the probing beam as well as the fringe contrast (leading directly to the phase shift time derivative) can be reconstructed simultaneously from such a complex interferogram. In this paper it will be demonstrated that even in the case of a not particularly good diagnostic beam quality these three quantities can be reconstructed with a high degree of accuracy provided both the diagnostic beam as well as the corresponding optical line feature a reasonable stability. Such stability requirement is important as in an ideal case four shots need to be gradually recorded (one by one): the signal complex interferogram, the reference interferogram as well as the intensity structures of the signal and reference part of the diagnostic beam. Two examples of complex interferograms obtained in experiments will be analyzed: the laser produced plasma (spark in the air) and the high pressure gas jet. A general ray-tracing based iterative algorithm will be outlined in order to increase a precision of the index of refraction spatial profile taking into account refraction effects (omitted in the Abel inversion) and employing the original reconstructed phase shift and amplitude.

  12. Spectrophotometric determination of fluoride in dosage forms and dental preparations.

    Science.gov (United States)

    Săndulescu, R; Florean, E; Roman, L; Mirel, S; Oprean, R; Suciu, P

    1996-06-01

    The method is based upon the reaction between fluoride ions and the coloured complex of Fe(III) with methyl salicylate to form the stable, colourless hexaflouride complex of iron. The conditions of the method (pH, time and combination ratio) were studied and a standard curve was obtained for 0.01-0.08 mg NaF ml-1, at 525 nm. A study was conducted on interference with complexing anions of Fe(III), cations that react with fluoride ions and with common ingredients of dosage forms and dental preparations. The method was validated and the results showed good precision (100.16 +/- = 2.33%) comparable with that of other analytical methods. Good results were obtained in the spectrophotometric determination of fluoride ions in a stomatological gel and in a toothpaste.

  13. Stable assembly of HIV-1 export complexes occurs cotranscriptionally

    DEFF Research Database (Denmark)

    Nawroth, Isabel; Mueller, Florian; Basyuk, Eugenia

    2014-01-01

    The HIV-1 Rev protein mediates export of unspliced and singly spliced viral transcripts by binding to the Rev response element (RRE) and recruiting the cellular export factor CRM1. Here, we investigated the recruitment of Rev to the transcription sites of HIV-1 reporters that splice either post......- or cotranscriptionally. In both cases, we observed that Rev localized to the transcription sites of the reporters and recruited CRM1. Rev and CRM1 remained at the reporter transcription sites when cells were treated with the splicing inhibitor Spliceostatin A (SSA), showing that the proteins associate with RNA prior...... to or during early spliceosome assembly. Fluorescence recovery after photobleaching (FRAP) revealed that Rev and CRM1 have similar kinetics as the HIV-1 RNA, indicating that Rev, CRM1, and RRE-containing RNAs are released from the site of transcription in one single export complex. These results suggest...

  14. Interaction of cesium ions with calix[2]furan[4]pyrrole and its fluoride complex

    Czech Academy of Sciences Publication Activity Database

    Kříž, Jaroslav; Dybal, Jiří; Makrlík, E.; Kohnke, F. H.

    2012-01-01

    Roč. 541, 10 July (2012), s. 27-31 ISSN 0009-2614 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : calix[2]furan[4]pyrrole * Cs complex * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.145, year: 2012

  15. Utilizing the σ-complex stability for quantifying reactivity in nucleophilic substitution of aromatic fluorides

    Directory of Open Access Journals (Sweden)

    Magnus Liljenberg

    2013-04-01

    Full Text Available A computational approach using density functional theory to compute the energies of the possible σ-complex reaction intermediates, the “σ-complex approach”, has been shown to be very useful in predicting regioselectivity, in electrophilic as well as nucleophilic aromatic substitution. In this article we give a short overview of the background for these investigations and the general requirements for predictive reactivity models for the pharmaceutical industry. We also present new results regarding the reaction rates and regioselectivities in nucleophilic substitution of fluorinated aromatics. They were rationalized by investigating linear correlations between experimental rate constants (k from the literature with a theoretical quantity, which we call the sigma stability (SS. The SS is the energy change associated with formation of the intermediate σ-complex by attachment of the nucleophile to the aromatic ring. The correlations, which include both neutral (NH3 and anionic (MeO− nucleophiles are quite satisfactory (r = 0.93 to r = 0.99, and SS is thus useful for quantifying both global (substrate and local (positional reactivity in SNAr reactions of fluorinated aromatic substrates. A mechanistic analysis shows that the geometric structure of the σ-complex resembles the rate-limiting transition state and that this provides a rationale for the observed correlations between the SS and the reaction rate.

  16. FLUORIDE REMOVAL BY ADSORPTION ON THERMALLY ...

    African Journals Online (AJOL)

    Preferred Customer

    capability. Speciation analysis reveals that at low initial fluoride concentrations the dissolution of gibbsite is facilitated by the adsorption of fluoride onto gibbsite. This may result in the formation of aluminum fluoro complexes in water. KEY WORDS: Fluoride removal, Laterite soils, Speciation analysis, Adsorption capacity, ...

  17. G protein-coupled receptors form stable complexes with inwardly rectifying potassium channels and adenylyl cyclase.

    Science.gov (United States)

    Lavine, Natalie; Ethier, Nathalie; Oak, James N; Pei, Lin; Liu, Fang; Trieu, Phan; Rebois, R Victor; Bouvier, Michel; Hebert, Terence E; Van Tol, Hubert H M

    2002-11-29

    A large number of studies have demonstrated co-purification or co-immunoprecipitation of receptors with G proteins. We have begun to look for the presence of effector molecules in these receptor complexes. Co-expression of different channel and receptor permutations in COS-7 and HEK 293 cells in combination with co-immunoprecipitation experiments established that the dopamine D(2) and D(4), and beta(2)-adrenergic receptors (beta(2)-AR) form stable complexes with Kir3 channels. The D(4)/Kir3 and D(2) receptor/Kir3 interaction does not occur when the channel and receptor are expressed separately and mixed prior to immunoprecipitation, indicating that the interaction is not an artifact of the experimental protocol and reflects a biosynthetic event. The observed complexes are stable in that they are not disrupted by receptor activation or modulation of G protein alpha subunit function. However, using a peptide that binds Gbetagamma (betaARKct), we show that Gbetagamma is critical for dopamine receptor-Kir3 complex formation, but not for maintenance of the complex. We also provide evidence that Kir3 channels and another effector, adenylyl cyclase, are stably associated with the beta(2)-adrenergic receptor and can be co-immunoprecipitated by anti-receptor antibodies. Using bioluminescence resonance energy transfer, we have shown that in living cells under physiological conditions, beta(2)AR interacts directly with Kir3.1/3.4 and Kir3.1/3.2c heterotetramers as well as with adenylyl cyclase. All of these interactions are stable in the presence of receptor agonists, suggesting that these signaling complexes persist during signal transduction. In addition, we provide evidence that the receptor-effector complexes are also found in vivo. The observation that several G protein-coupled receptors form stable complexes with their effectors suggests that this arrangement might be a general feature of G protein-coupled signal transduction.

  18. Modelling of the flow of stable air over a complex region

    CSIR Research Space (South Africa)

    Scholtz, MT

    1976-01-01

    Full Text Available The flow of stable air over a general region of complex topography and non-uniform surface temperature has been investigated. In order to gain further understanding of the motion of surface air, it was necessary to study the vertical structure...

  19. Magnetic interactions through fluoride

    DEFF Research Database (Denmark)

    Pedersen, Kasper Steen; Sigrist, Marc; Weihe, Høgni

    2014-01-01

    The nature of the magnetic interaction through fluoride in a simple, dinuclear manganese(III) complex (1), bridged by a single fluoride ion in a perfectly linear fashion, is established by experiment and density functional theory. The magnitude of the antiferromagnetic exchange interaction...... and the manganese(III) zero-field-splitting parameters are unambiguously determined by inelastic neutron scattering to yield J = 33.0(2) cm(-1) (Ĥ = JŜ1·Ŝ2 Hamiltonian definition) and single-ion D = -4.0(1) cm(-1). Additionally, high-field, high-frequency electron paramagnetic resonance and magnetic measurements...

  20. Relation of ABO blood groups to coronary lesion complexity in patients with stable coronary artery disease.

    Science.gov (United States)

    Kaya, Ahmet; Tanboğa, İbrahim Halil; Kurt, Mustafa; Işık, Turgay; Kaya, Yasemin; Günaydın, Zeki Yüksel; Aksakal, Enbiya

    2014-02-01

    We aimed to investigate the relationship between ABO blood groups and complexity of coronary lesions assessed by SYNTAX score (SS) in stable coronary artery disease (CAD) patients. Our cross-sectional and observational study population consisted of 559 stable CAD patients. From all patients, ABO blood group was determined and the SS was calculated as low SYNTAX score (0-22), intermediate SYNTAX (23-32) score and high SYNTAX score (>32). Statistical analysis was performed using Student's t-test or Mann-Whitney U test, ANOVA, or Kruskal-Wallis test and chi-square test. Multiple logistic regression analysis was used to identify the independent predictors of high SS. The analysis between the SS tertiles revealed that the frequency of non-O blood group was significantly higher in the upper SS tertiles (56.2% vs. 75.9 vs. 80.2%, pABO blood groups and complexity of angiographic CAD.

  1. Scandium fluorides

    International Nuclear Information System (INIS)

    Melnikov, P.; Nalin, M.; Messaddeq, Y.

    1997-01-01

    A new modification of scandium fluoride has been synthesised. The compound is deficient in fluorine, with the composition ScF 2.76 . It belongs to the tetragonal system, lattice parameters being a=3.792 and c=6.740 A and may be obtained at low temperatures by the decomposition of the precursor NH 4 ScF 4 . The reaction is topotactic, tetragonal parameters of the precursor are a=4.021 and c=6.744 A. Structural relationships with various fluorides and ammonium aminofluorides are discussed. This synthesis route with IR-assisted decomposition should be considered as a soft-chemistry approach. (orig.)

  2. Lithological Influences on Occurrence of High-Fluoride Waters in The Central Kenya Rift

    Science.gov (United States)

    Olaka, L. A.; Musolff, A.; Mulch, A.; Olago, D.; Odada, E. O.

    2013-12-01

    Within the East African rift, groundwater recharge results from the complex interplay of geology, land cover, geomorphology, climate and on going volcano-tectonic processes across a broad range of spatial and temporal scales. The interrelationships between these factors create complex patterns of water availability, reliability and quality. The hydrochemical evolution of the waters is further complex due to the different climatic regimes and geothermal processes going on in this area. High fluoridic waters within the rift have been reported by few studies, while dental fluorosis is high among the inhabitants of the rift. The natural sources of fluoride in waters can be from weathering of fluorine bearing minerals in rocks, volcanic or fumarolic activities. Fluoride concentration in water depends on a number of factors including pH, temperature, time of water-rock formation contact and geochemical processes. Knowledge of the sources and dispersion of fluoride in both surface and groundwaters within the central Kenya rift and seasonal variations between wet and dry seasons is still poor. The Central Kenya rift is marked by active tectonics, volcanic activity and fumarolic activity, the rocks are majorly volcanics: rhyolites, tuffs, basalts, phonolites, ashes and agglomerates some are highly fractured. Major NW-SE faults bound the rift escarpment while the rift floor is marked by N-S striking faults We combine petrographic, hydrochemistry and structural information to determine the sources and enrichment pathways of high fluoridic waters within the Naivasha catchment. A total of 120 water samples for both the dry season (January-February2012) and after wet season (June-July 2013) from springs, rivers, lakes, hand dug wells, fumaroles and boreholes within the Naivasha catchment are collected and analysed for fluoride, physicochemical parameters and stable isotopes (δ2 H, δ18 O) in order to determine the origin and evolution of the waters. Additionally, 30 soil and

  3. Stable incorporation versus dynamic exchange of β subunits in a native Ca2+ channel complex.

    Science.gov (United States)

    Campiglio, Marta; Di Biase, Valentina; Tuluc, Petronel; Flucher, Bernhard E

    2013-05-01

    Voltage-gated Ca(2+) channels are multi-subunit membrane proteins that transduce depolarization into cellular functions such as excitation-contraction coupling in muscle or neurotransmitter release in neurons. The auxiliary β subunits function in membrane targeting of the channel and modulation of its gating properties. However, whether β subunits can reversibly interact with, and thus differentially modulate, channels in the membrane is still unresolved. In the present study we applied fluorescence recovery after photobleaching (FRAP) of GFP-tagged α1 and β subunits expressed in dysgenic myotubes to study the relative dynamics of these Ca(2+) channel subunits for the first time in a native functional signaling complex. Identical fluorescence recovery rates of both subunits indicate stable interactions, distinct recovery rates indicate dynamic interactions. Whereas the skeletal muscle β1a isoform formed stable complexes with CaV1.1 and CaV1.2, the non-skeletal muscle β2a and β4b isoforms dynamically interacted with both α1 subunits. Neither replacing the I-II loop of CaV1.1 with that of CaV2.1, nor deletions in the proximal I-II loop, known to change the orientation of β relative to the α1 subunit, altered the specific dynamic properties of the β subunits. In contrast, a single residue substitution in the α interaction pocket of β1aM293A increased the FRAP rate threefold. Taken together, these findings indicate that in skeletal muscle triads the homologous β1a subunit forms a stable complex, whereas the heterologous β2a and β4b subunits form dynamic complexes with the Ca(2+) channel. The distinct binding properties are not determined by differences in the I-II loop sequences of the α1 subunits, but are intrinsic properties of the β subunit isoforms.

  4. Spectrophotometric determination of fluoride in drinking water using ...

    African Journals Online (AJOL)

    2011-03-14

    Mar 14, 2011 ... A sensitive spectrophotometric determination of fluoride in drinking water has been developed using aluminium complexes ... Keywords: Fluoride analysis, spectrophotometric method, drinking water, aluminium triphenylmethane dye ..... mechanism at the mercury electrode in neutral and alkaline aque-.

  5. Highly active and stable oxaloacetate decarboxylase Na⁺ pump complex for structural analysis.

    Science.gov (United States)

    Inoue, Michio; Li, Xiaodan

    2015-11-01

    The oxaloacetate decarboxylase primary Na(+) pump (Oad) produces energy for the surviving of some pathogenic bacteria under anaerobic conditions. Oad composes of three subunits: Oad-α, a biotinylated soluble subunit and catalyzes the decarboxylation of oxaloacetate; Oad-β, a transmembrane subunit and functions as a Na(+) pump; and Oad-γ, a single transmembrane α-helical anchor subunit and assembles Oad-α/β/γ complex. The molecular mechanism of Oad complex coupling the exothermic decarboxylation to generate the Na(+) electrochemical gradient remains unsolved. Our biophysical and biochemical studies suggested that the stoichiometry of Oad complex from Vibrio cholerae composed of α, β, γ in 4:2:2 stoichiometry not that of 4:4:4. The high-resolution structure determination of the Oad complex would reveal the energetic transformation mechanism from the catalytical soluble α subunit to membrane β subunit. Sufficient amount stable, conformational homogenous and active Oad complex with the right stoichiometry is the prerequisite for structural analysis. Here we report an easy and reproducible protocol to obtain high quantity and quality Oad complex protein for structural analysis. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Water-stable fac-{TcO₃}⁺ complexes - a new field of technetium chemistry.

    Science.gov (United States)

    Braband, Henrik

    2011-01-01

    The development of technetium chemistry has been lagging behind that of its heavier congener rhenium, primarily because the inherent radioactivity of all Tc isotopes has limited the number of laboratories that can study the chemistry of this fascinating element. Although technetium is an artificial element, it is not rare. Significant amounts of the isotope (99)Tc are produced every day as a fission byproduct in nuclear power plants. Therefore, a fundamental understanding of the chemistry of (99)Tc is essential to avoid its release into the environment. In this article the chemistry of technetium at its highest oxidation state (+VII) is reviewed with a special focus on recent developments which make water-stable complexes of the general type [TcO(3)(tacn-R)](+) (tacn-R = 1,4,7-triazacyclononane or derivatives) accessible. Complexes containing the fac-{TcO(3)}(+) core display a unique reactivity. In analogy to [OsO(4)] and [RuO(4)], complexes containing the fac-{TcO(3)}(+) core undergo with alkenes metal-mediated, vicinal cis-dihydroxylation reactions (alkene-glycol interconversion) in water via a (3+2)-cycloaddition reaction. Therefore, water-stable fac-{(99m)TcO(3)}(+) complexes pave the way for a new labeling strategy for radiopharmaceutical applications, based on (3+2)-cycloaddition reactions. This new concept for the labeling of biomolecules with small [(99m)TcO(3)(tacn-R)](+)-type complexes by way of a (3+2)-cycloaddition with alkenes is discussed in detail. The herein reported developments in high-valent technetium chemistry create a new field of research with this artificial element. This demonstrates the potential of fundamental research to provide new impetus of innovation for the development of new methods for radiopharmaceutical applications.

  7. A Stable Coordination Complex of Rh(IV) in an N,O-Donor Environment

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Shashi B. [Department of Chemistry, Yale University, 225 Prospect; Shopov, Dimitar Y. [Department of Chemistry, Yale University, 225 Prospect; Sharninghausen, Liam S. [Department of Chemistry, Yale University, 225 Prospect; Vinyard, David J. [Department of Chemistry, Yale University, 225 Prospect; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225 Prospect; Brudvig, Gary W. [Department of Chemistry, Yale University, 225 Prospect; Crabtree, Robert H. [Department of Chemistry, Yale University, 225 Prospect

    2015-12-10

    We describe facial and meridional isomers of [RhIII(pyalk)3], as well as meridional [RhIV(pyalk)3]+ {pyalk =2-(2-pyridyl)-2-propanoate}, the first coordination complex in an N,O-donor environment to show a clean, reversible RhIII/IV redox couple and to have a stable Rh(IV) form, which we characterize by EPR and UV–visible spectroscopy as well as X-ray crystallography. The unprecedented stability of the Rh(IV) species is ascribed to the exceptional donor strength of the ligands, their oxidation resistance, and the meridional coordination geometry.

  8. Bottled Water and Fluoride

    Science.gov (United States)

    ... What's this? Submit What's this? Submit Button Bottled Water Recommend on Facebook Tweet Share Compartir Consumers drink ... questions about bottled water and fluoride. Does bottled water contain fluoride? Bottled water products may contain fluoride, ...

  9. Distribution tactics for success in turbulent versus stable environments: A complexity theory approach

    Directory of Open Access Journals (Sweden)

    Roger Bruce Mason

    2013-05-01

    Full Text Available This article proposes that the external environment influences the choice of distribution tactics. Since businesses and markets are complex adaptive systems, using complexity theory to understand such environments is necessary, but it has not been widely researched. A qualitative case method using in-depth interviews investigated four successful, versus less successful, companies in turbulent versus stable environments. The results tentatively confirmed that the more successful company, in a turbulent market, sees distribution activities as less important than other aspects of the marketing mix, but uses them to stabilise customer relationships and to maintain distribution processes. These findings can benefit marketers by emphasising a new way to consider place activities. How marketers can be assisted, and suggestions for further research, are provided.

  10. Distribution tactics for success in turbulent versus stable environments: A complexity theory approach

    Directory of Open Access Journals (Sweden)

    Roger Bruce Mason

    2013-11-01

    Full Text Available This article proposes that the external environment influences the choice of distribution tactics. Since businesses and markets are complex adaptive systems, using complexity theory to understand such environments is necessary, but it has not been widely researched. A qualitative case method using in-depth interviews investigated four successful, versus less successful, companies in turbulent versus stable environments. The results tentatively confirmed that the more successful company, in a turbulent market, sees distribution activities as less important than other aspects of the marketing mix, but uses them to stabilise customer relationships and to maintain distribution processes. These findings can benefit marketers by emphasising a new way to consider place activities. How marketers can be assisted, and suggestions for further research, are provided.

  11. Indefinitely stable iron(IV) cage complexes formed in water by air oxidation

    Science.gov (United States)

    Tomyn, Stefania; Shylin, Sergii I.; Bykov, Dmytro; Ksenofontov, Vadim; Gumienna-Kontecka, Elzbieta; Bon, Volodymyr; Fritsky, Igor O.

    2017-01-01

    In nature, iron, the fourth most abundant element of the Earth's crust, occurs in its stable forms either as the native metal or in its compounds in the +2 or +3 (low-valent) oxidation states. High-valent iron (+4, +5, +6) compounds are not formed spontaneously at ambient conditions, and the ones obtained synthetically appear to be unstable in polar organic solvents, especially aqueous solutions, and this is what limits their studies and use. Here we describe unprecedented iron(IV) hexahydrazide clathrochelate complexes that are assembled in alkaline aqueous media from iron(III) salts, oxalodihydrazide and formaldehyde in the course of a metal-templated reaction accompanied by air oxidation. The complexes can exist indefinitely at ambient conditions without any sign of decomposition in water, nonaqueous solutions and in the solid state. We anticipate that our findings may open a way to aqueous solution and polynuclear high-valent iron chemistry that remains underexplored and presents an important challenge.

  12. Very stable high molecular mass multiprotein complex with DNase and amylase activities in human milk.

    Science.gov (United States)

    Soboleva, Svetlana E; Dmitrenok, Pavel S; Verkhovod, Timofey D; Buneva, Valentina N; Sedykh, Sergey E; Nevinsky, Georgy A

    2015-01-01

    For breastfed infants, human milk is more than a source of nutrients; it furnishes a wide array of proteins, peptides, antibodies, and other components promoting neonatal growth and protecting infants from viral and bacterial infection. It has been proposed that most biological processes are performed by protein complexes. Therefore, identification and characterization of human milk components including protein complexes is important for understanding the function of milk. Using gel filtration, we have purified a stable high molecular mass (~1000 kDa) multiprotein complex (SPC) from 15 preparations of human milk. Light scattering and gel filtration showed that the SPC was stable in the presence of high concentrations of NaCl and MgCl2 but dissociated efficiently under the conditions that destroy immunocomplexes (2 M MgCl2 , 0.5 M NaCl, and 10 mM DTT). Such a stable complex is unlikely to be a casual associate of different proteins. The relative content of the individual SPCs varied from 6% to 25% of the total milk protein. According to electrophoretic and mass spectrometry analysis, all 15 SPCs contained lactoferrin (LF) and α-lactalbumin as major proteins, whereas human milk albumin and β-casein were present in moderate or minor amounts; a different content of IgGs and sIgAs was observed. All SPCs efficiently hydrolyzed Plasmid supercoiled DNA and maltoheptaose. Some freshly prepared SPC preparations contained not only intact LF but also small amounts of its fragments, which appeared in all SPCs during their prolonged storage; the fragments, similar to intact LF, possessed DNase and amylase activities. LF is found in human epithelial secretions, barrier body fluids, and in the secondary granules of leukocytes. LF is a protein of the acute phase response and nonspecific defense against different types of microbial and viral infections. Therefore, LF complexes with other proteins may be important for its functions not only in human milk. Copyright © 2014

  13. Concord grape pomace polyphenols complexed to soy protein isolate are stable and hypoglycemic in diabetic mice.

    Science.gov (United States)

    Roopchand, Diana E; Kuhn, Peter; Krueger, Christian G; Moskal, Kristin; Lila, Mary Ann; Raskin, Ilya

    2013-11-27

    Polyphenols extracted from Concord grape pomace were stabilized by complexation to soy protein isolate (SPI) to produce grape polyphenol-SPI complex (GP-SPI) containing 5% or 10% grape polyphenols. LC-MS and MALDI-TOF analysis showed that a broad range of phytochemicals were present in the grape pomace extract. Anthocyanins and total polyphenols in the GP-SPI complex were stable after a 16-week incubation at 37 °C but were reduced by up 60% in dried grape pomace extract. Compared to vehicle (236 ± 34 mg/dL), a single dose of 300 mg/kg GP-SPI (184 ± 32 mg/dL) or 500 mg/kg GP-SPI (177 ± 28 mg/dL) having 5% grape polyphenols significantly lowered blood glucose in obese and hyperglycemic C57BL/6 mice 6 h after administration. GP-SPI allows the capture of grape pomace polyphenols in a protein-rich food matrix and may be useful as a functional food ingredient for the management of blood glucose levels.

  14. some factors influencing the free fluoride content in black tea

    African Journals Online (AJOL)

    ACSS

    that is more resistant to erosion by plaque acid and demonstrates a lower surface energy which makes plaque adhesion more difficult. However, excessive intake ... fluoride-halide complexes present in the soil decompose into aluminium and fluoride ions, enhancing their availability to tea plants. The free fluoride ion is then ...

  15. New glyme-cyclic imide lithium salt complexes as thermally stable electrolytes for lithium batteries

    Science.gov (United States)

    Tamura, Takashi; Hachida, Takeshi; Yoshida, Kazuki; Tachikawa, Naoki; Dokko, Kaoru; Watanabe, Masayoshi

    New glyme-Li salt complexes were prepared by mixing equimolar amounts of a novel cyclic imide lithium salt LiN(C 2F 4S 2O 4) (LiCTFSI) and a glyme (triglyme (G3) or tetraglyme (G4)). The glyme-Li salt complexes, [Li(G3)][CTFSI] and [Li(G4)][CTFSI], are solid and liquid, respectively, at room temperature. The thermal stability of [Li(G4)][CTFSI] is much higher than that of pure G4, and the vapor pressure of [Li(G4)][CTFSI] is negligible at temperatures lower than 100 °C. Although the viscosity of [Li(G4)][CTFSI] is high (132.0 mPa s at 30 °C), because of its high molar concentration (ca. 3 mol dm -3), its ionic conductivity at 30 °C is relatively high, i.e., 0.8 mS cm -1, which is slightly lower than that of a conventional organic electrolyte solution (1 mol dm -3 LiTFSI dissolved in propylene carbonate). The self-diffusion coefficients of a Li + cation, a CTFSI - anion, and a glyme molecule were measured by the pulsed gradient spin-echo NMR method (PGSE-NMR). The ionicity (dissociativity) of [Li(G4)][CTFSI] at 30 °C is ca. 0.5, as estimated from the PGSE-NMR diffusivity measurements and the ionic conductivity measurements. Results of linear sweep voltammetry revealed that [Li(G4)][CTFSI] is electrochemically stable in an electrode potential range of 0-4.5 V vs. Li/Li +. The reversible deposition-stripping behavior of lithium was observed by cyclic voltammetry. The [LiCoO 2|[Li(G4)][CTFSI]|Li metal] cell showed a stable charge-discharge cycling behavior during 50 cycles, indicating that the [Li(G4)][CTFSI] complex is applicable to a 4 V class lithium secondary battery.

  16. Fluoride Nanoscintillators

    Directory of Open Access Journals (Sweden)

    Luiz G. Jacobsohn

    2011-01-01

    Full Text Available A preliminary investigation of the scintillation response of rare earth-doped fluoride nanoparticles is reported. Nanoparticles of CaF2 : Eu, BaF2 : Ce, and LaF3 : Eu were produced by precipitation methods using ammonium di-n-octadecyldithiophosphate (ADDP as a ligand that controls growth and lessens agglomeration. The structure and morphology were characterized by means of X-ray diffraction and transmission electron microscopy, while the scintillation properties of the nanoparticles were determined by means of X-ray and 241Am irradiation. The unique aspect of scintillation of nanoparticles is related to the migration of carriers in the nanoscintillator. Our results showed that even nanoparticles as small as ~4 nm in size effectively scintillate, despite the diffusion length of e-h pairs being considerably larger than the nanoparticles themselves, and suggest that nanoparticles can be used for radiation detection.

  17. Calculation of equilibrium stable isotope partition function ratios for aqueous zinc complexes and metallic zinc

    Science.gov (United States)

    Black, Jay R.; Kavner, Abby; Schauble, Edwin A.

    2011-02-01

    The goal of this study is to determine reduced partition function ratios for a variety of species of zinc, both as a metal and in aqueous solutions in order to calculate equilibrium stable isotope partitioning. We present calculations of the magnitude of Zn stable-isotope fractionation ( 66,67,68Zn/ 64Zn) between aqueous species and metallic zinc using measured vibrational spectra (fit from neutron scattering studies of metallic zinc) and a variety of electronic structure models. The results show that the reduced metal, Zn(0), will be light in equilibrium with oxidized Zn(II) aqueous species, with the best estimates for the Zn(II)-Zn(0) fractionation between hexaquo species and metallic zinc being Δ 66/64Zn aq-metal ˜ 1.6‰ at 25 °C, and Δ 66/64Zn aq-metal ˜ 0.8‰ between the tetrachloro zinc complex and metallic zinc at 25 °C using B3LYP/aug-cc-pVDZ level of theory and basis set. To examine the behavior of zinc in various aqueous solution chemistries, models for Zn(II) complex speciation were used to determine which species are thermodynamically favorable and abundant under a variety of different conditions relevant to natural waters, experimental and industrial solutions. The optimal molecular geometries for [Zn(H 2O) 6] 2+, [Zn(H 2O) 6]·SO 4, [ZnCl 4] 2- and [Zn(H 2O) 3(C 3H 5O(COO) 3)] - complexes in various states of solvation, protonation and coordination were calculated at various levels of electronic structure theory and basis set size. Isotopic reduced partition function ratios were calculated from frequency analyses of these optimized structures. Increasing the basis set size typically led to a decrease in the calculated reduced partition function ratios of ˜0.5‰ with values approaching a plateau using the aug-cc-pVDZ basis set or larger. The widest range of species were studied at the B3LYP/LAN2DZ/6-31G ∗ level of theory and basis-set size for comparison. Aqueous zinc complexes where oxygen is bound to the metal center tended to have the

  18. Highly selective "turn-on" fluorescent sensing of fluoride ion based on a conjugated polymer thin film-Fe3+ complex.

    Science.gov (United States)

    Ding, Wanchuan; Xu, Jingkun; Wen, Yangping; Zhang, Jie; Liu, Hongtao; Zhang, Zhouxiang

    2017-05-15

    We designed a new fluorescent conjugated polymer thin film sensor via direct electropolymerization of the corresponding electroactive monomer M onto the surface of ITO electrode, and the thin film-Fe 3+ complex was used for the highly-selective detection of fluoride ion (F - ) in water environmental samples. The as-obtained thin film could effectively detect Fe 3+ as a selective turn-off fluorescent sensor, and exhibited outstanding reversibility. This film in the presence of Fe 3+ showed a highly selective turn-on response toward F - over other anions with a 5-fold enhancement in the fluorescence intensity. F - with a relatively wide concentration range from 10 μM to 3 mM could be determined in a rather simple and sensitive manner with a detection limit of 6.78 μM (0.128 ppm). Analytical applicability of the film-Fe 3+ complex for determining the levels of F - in environmental water samples has been successfully demonstrated by fluorescent analysis with satisfactory results. This strategy will provide a new approach for the facile design of new molecular sensing devices and practical application in environments. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. On the interconnection of stable protein complexes: inter-complex hubs and their conservation in Saccharomyces cerevisiae and Homo sapiens networks.

    Science.gov (United States)

    Guerra, Concettina

    2015-01-01

    Protein complexes are key molecular entities that perform a variety of essential cellular functions. The connectivity of proteins within a complex has been widely investigated with both experimental and computational techniques. We developed a computational approach to identify and characterise proteins that play a role in interconnecting complexes. We computed a measure of inter-complex centrality, the crossroad index, based on disjoint paths connecting proteins in distinct complexes and identified inter-complex hubs as proteins with a high value of the crossroad index. We applied the approach to a set of stable complexes in Saccharomyces cerevisiae and in Homo sapiens. Just as done for hubs, we evaluated the topological and biological properties of inter-complex hubs addressing the following questions. Do inter-complex hubs tend to be evolutionary conserved? What is the relation between crossroad index and essentiality? We found a good correlation between inter-complex hubs and both evolutionary conservation and essentiality.

  20. A critical review on the stability constants of the fluoride complexes of actinides in aqueous solution and their correlation with fundamental properties of the ions

    International Nuclear Information System (INIS)

    Chaudhuri, N.K.; Sawant, R.M.; Sood, D.D.

    1999-01-01

    Literature data on the stability constants of the fluoride complexes of the actinides in different oxidation states have been compiled. In order to have a reasonable inter-comparison, the stability constant (β 1 ) values obtained in diverse ionic strength media are converted to so called thermodynamic stability constants, β 1 0 using the DAVIES equation (a modification of Debye-Huckel equation). A correlation of the β 1 0 values with the fundamental properties of the actinide ions using various models available in the literature has been attempted. Using the values of ionic radii and best available values of the stability constants of a large number of metal ions from recent compilations a comparative study of the various models or relations available in the literature has been tried. For metal ions in general, the semi-empirical relation recently developed by BROWN, SYLVA and ELLIS (BSE equation) gives the best correlation. In an attempt to accommodate the unusual trend in the stability constants of the tetravalent actinides a modification in a parameter of the BSE equation has been proposed. Good agreement between the theoretically calculated and experimentally determined values for actinides in different oxidation states is obtained in most of the cases. Further improvements in theoretical relation as well as experimental data are required for better correlation. (author)

  1. Crystal growth of fluoridated hydroxyapatites inhibited in the presence of gelatin.

    Science.gov (United States)

    Okazaki, M; Takahashi, J; Kumura, H

    1989-12-01

    Three types of fluoridated hydroxyapatites were synthesized in the presence of low concentrations of gelatin solution. The crystallinity of gelatin-free fluoridated hydroxyapatites increased at high degree of fluoridation, after it showed complex behavior at lower fluoride content. However, increasing of gelatin concentration in the solution, the crystallinity decreased, especially at high fluoride content. Chemical analysis and a- and c-axis dimensions showed no significant difference among those series, and gelatin contents in the precipitates were negligible when compared with the supplied amounts. These results suggest that gelatin may inhibit the crystal growth of fluoridated apatites only as a surrounding factor, overcoming the promoting action of fluoride.

  2. Electrostatic interactions between polyglutamic acid and polylysine yields stable polyion complex micelles for deoxypodophyllotoxin delivery

    Directory of Open Access Journals (Sweden)

    Wang Y

    2017-10-01

    Full Text Available Yutong Wang,1–3,* Liping Huang,1,2,* Yan Shen,1,2,* Lidan Tang,1,2,4 Runing Sun,1,5 Di Shi,6 Thomas J Webster,6 Jiasheng Tu,1,2 Chunmeng Sun1,2 1Center for Research Development and Evaluation of Pharmaceutical Excipients and Generic Drugs, China Pharmaceutical University, 2State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, 3Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 4Changzhou Second People’s Hospital, Changzhou, 5School of Engineering, China Pharmaceutical University, Nanjing, People’s Republic of China; 6Department of Chemical Engineering, Northeastern University, Boston, MA, USA *These authors contributed equally to this work Abstract: To achieve enhanced physical stability of poly(ethylene glycol-poly(D,L-lactide polymeric micelles (PEG-PDLLA PMs, a mixture of methoxy PEG-PDLLA-polyglutamate (mPEG-PDLLA-PLG and mPEG-PDLLA-poly(L-lysine (mPEG-PDLLA-PLL copolymers was applied to self-assembled stable micelles with polyion-stabilized cores. Prior to micelle preparation, the synthetic copolymers were characterized by 1H-nuclear magnetic resonance (NMR and infrared spectroscopy (IR, and their molecular weights were calculated by 1H-NMR and gel permeation chromatography (GPC. Dialysis was used to prepare PMs with deoxypodophyllotoxin (DPT. Transmission electron microscopy (TEM images showed that DPT polyion complex micelles (DPT-PCMs were spherical, with uniform distribution and particle sizes of 36.3±0.8 nm. In addition, compared with nonpeptide-modified DPT-PMs, the stability of DPT-PCMs was significantly improved under various temperatures. In the meantime, the pH sensitivity induced by charged peptides allowed them to have a stronger antitumor effect and a pH-triggered release profile. As a result, the dynamic characteristic of DPT-PCM was retained, and high biocompatibility of DPT-PCM was observed in an in vivo study. These results

  3. Other Fluoride Products

    Science.gov (United States)

    ... Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States . MMWR , August 17, 2001; ... informed of both the benefit of protection against tooth decay and the possibility of dental fluorosis. Fluoride Gel and Foam Form Fluoride gel ...

  4. Fluoride glass fiber optics

    CERN Document Server

    Aggarwal, Ishwar D

    1991-01-01

    Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

  5. Interactions between HIV-1 reverse transcriptase and the downstream template strand in stable complexes with primer-template.

    Directory of Open Access Journals (Sweden)

    Wiriya Rutvisuttinunt

    Full Text Available Human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT forms stable ternary complexes in which RT is bound tightly at fixed positions on the primer-template (P/T. We have probed downstream interactions between RT and the template strand in the complex containing the incoming dNTP (+1 dNTP*RT*P/T complex and in the complex containing the pyrophosphate analog, foscarnet (foscarnet*RT*P/T complex.UV-induced cross-linking between RT and the DNA template strand was most efficient when a bromodeoxyuridine residue was placed in the +2 position (the first template position downstream from the incoming dNTP. Furthermore, formation of the +1 dNTP*RT*P/T complex on a biotin-containing template inhibited binding of streptavidin when biotin was in the +2 position on the template but not when the biotin was in the +3 position. Streptavidin pre-bound to a biotin residue in the template caused RT to stall two to three nucleotides upstream from the biotin residue. The downstream border of the complex formed by the stalled RT was mapped by digestion with exonuclease RecJ(F. UV-induced cross-linking of the complex formed by the pyrophosphate analog, foscarnet, with RT and P/T occurred preferentially with bromodeoxyuridine in the +1 position on the template in keeping with the location of RT one base upstream in the foscarnet*RT*P/T complex (i.e., in the pre-translocation position.For +1 dNTP*RT*P/T and foscarnet*RT*P/T stable complexes, tight interactions were observed between RT and the first unpaired template nucleotide following the bound dNTP or the primer terminus, respectively.

  6. Fluoride loaded polymeric nanoparticles for dental delivery.

    Science.gov (United States)

    Nguyen, Sanko; Escudero, Carlos; Sediqi, Nadia; Smistad, Gro; Hiorth, Marianne

    2017-06-15

    The overall aim of the present paper was to develop fluoride loaded nanoparticles based on the biopolymers chitosan, pectin, and alginate, for use in dental delivery. First, the preparation of nanoparticles in the presence of sodium fluoride (NaF) as the active ingredient by ionic gelation was investigated followed by an evaluation of their drug entrapment and release properties. Chitosan formed stable, spherical, and monodisperse nanoparticles in the presence of NaF and tripolyphoshate as the crosslinker, whereas alginate and pectin were not able to form any definite nanostructures in similar conditions. The fluoride loading capacity was found to be 33-113ppm, and the entrapment efficiency 3.6-6.2% for chitosan nanoparticles prepared in 0.2-0.4% (w/w) NaF, respectively. A steady increase in the fluoride release was observed for chitosan nanoparticles prepared in 0.2% NaF both in pH5 and 7 until it reached a maximum at time point 4h and maintained at this level for at least 24h. Similar profiles were observed for formulations prepared in 0.4% NaF; however the fluoride was released at a higher level at pH5. The low concentration, but continuous delivery of fluoride from the chitosan nanoparticles, with possible expedited release in acidic environment, makes these formulations highly promising as dental delivery systems in the protection against caries development. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Phosphorescent Pt(II) and Pd(II) Complexes for Efficient, High-Color-Quality, and Stable OLEDs.

    Science.gov (United States)

    Fleetham, Tyler; Li, Guijie; Li, Jian

    2017-02-01

    Phosphorescent organic light-emitting diodes (OLEDs) are leading candidates for next-generation displays and solid-state lighting technologies. Much of the academic and commercial pursuits in phosphorescent OLEDs have been dominated by Ir(III) complexes. Over the past decade recent developments have enabled square planar Pt(II) and Pd(II) complexes to meet or exceed the performance of Ir complexes in many aspects. In particular, the development of N-heterocyclic carbene-based emitters and tetradentate cyclometalated Pt and Pd complexes have significantly improved the emission efficiency and reduced their radiative lifetimes making them competitive with the best reported Ir complexes. Furthermore, their unique and diverse molecular design possibilities have enabled exciting photophysical attributes including narrower emission spectra, excimer -based white emission, and thermally activated delayed fluorescence. These developments have enabled the fabrication of efficient and "pure" blue OLEDs, single-doped white devices with EQEs of over 25% and high CRI, and device operational lifetimes which show early promise that square planar metal complexes can be stable enough for commercialization. These accomplishments have brought Pt complexes to the forefront of academic research. The molecular design strategies, photophysical characteristics, and device performance resulting from the major advancements in emissive Pt and Pd square planar complexes are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Extremely stable soluble high molecular mass multi-protein complex with DNase activity in human placental tissue.

    Directory of Open Access Journals (Sweden)

    Evgeniya E Burkova

    Full Text Available Human placenta is an organ which protects, feeds, and regulates the grooving of the embryo. Therefore, identification and characterization of placental components including proteins and their multi-protein complexes is an important step to understanding the placenta function. We have obtained and analyzed for the first time an extremely stable multi-protein complex (SPC, ∼ 1000 kDa from the soluble fraction of three human placentas. By gel filtration on Sepharose-4B, the SPC was well separated from other proteins of the placenta extract. Light scattering measurements and gel filtration showed that the SPC is stable in the presence of NaCl, MgCl2, acetonitrile, guanidinium chloride, and Triton in high concentrations, but dissociates efficiently in the presence of 8 M urea, 50 mM EDTA, and 0.5 M NaCl. Such a stable complex is unlikely to be a casual associate of different proteins. According to SDS-PAGE and MALDI mass spectrometry data, this complex contains many major glycosylated proteins with low and moderate molecular masses (MMs 4-14 kDa and several moderately abundant (79.3, 68.5, 52.8, and 27.2 kDa as well as minor proteins with higher MMs. The SPC treatment with dithiothreitol led to a disappearance of some protein bands and revealed proteins with lower MMs. The SPCs from three placentas efficiently hydrolyzed plasmid supercoiled DNA with comparable rates and possess at least two DNA-binding sites with different affinities for a 12-mer oligonucleotide. Progress in study of placental protein complexes can promote understanding of their biological functions.

  9. Pyridine and phosphonate containing ligands for stable lanthanide complexation. An experimental and theoretical study to assess the solution structure.

    Science.gov (United States)

    Mato-Iglesias, Marta; Balogh, Edina; Platas-Iglesias, Carlos; Tóth, Eva; de Blas, Andrés; Rodríguez Blas, Teresa

    2006-12-07

    We report an experimental and theoretical study of the stability and solution structure of lanthanide complexes with two novel ligands containing pyridine units and phosphonate pendant arms on either ethane-1,2-diamine (L2) or cyclohexane-1,2-diamine (L3) backbones. Potentiometric studies have been carried out to determine the protonation constants of the ligands and the stability constants of the complexes with Gd(III) and the endogenous metal ions Zn(II) and Cu(II). While the stability constant of the GdL2 complex is too high to be determined by direct pH-potentiometric titrations, the cyclohexyl derivative GdL3 has a lower and assessable stability (log K(GdL3)=17.62). Due to the presence of the phosphonate groups, various protonated species can be detected up to pH approximately 8 for both ligands and all metal ions studied. The molecular clusters [Ln(L)(H2O)](3-).19H2O (Ln=La, Nd, Ho or Lu; L=L2 or L3) were characterized by theoretical calculations at the HF level. Our calculations provide two minimum energy geometries where the ligand adopts different conformations: twist-wrap (tw), in which the ligand wraps around the metal ion by twisting the pyridyl units relative to each other, and twist-fold (tf), where the slight twisting of the pyridyl units is accompanied by an overall folding of the two pyridine units towards one of the phosphonate groups. The relative free energies of the tw and tf conformations of [Ln(L)(H2O)]3- (L=L2, L3) complexes calculated in aqueous solution (C-PCM) by using the B3LYP model indicate that the tw form is the most stable one along the whole lanthanide series for the complexes of L3, while for those of L2 only the Gd(III) complex is more stable in the tf conformation by ca. 0.5 kcal mol-1. 1H NMR studies of the Eu(III) complex of L3 show the initial formation of the tf complex in aqueous solution, which slowly converts to the thermodynamically stable tw form. The structures calculated for the Nd(III) complexes are in reasonably

  10. [Fluoride release in children's toothpastes].

    Science.gov (United States)

    Sättler, M; Hanfland, D; Wetzel, W E

    1993-01-01

    Comparative investigations of six toothpastes for children obtainable on the German market were carried out to determine their bioavailable fluoride concentration in vitro and in vivo. Four products contained sodium monofluorophosphate, one sodium fluoride and another amine fluoride. The product containing sodium fluoride had, both in the toothpaste-saliva-mixture in the test-tube as well as in the aquadest-toothpaste-saliva-mixture, derived from the oral cavity the maximum proportion of dissolved fluoride (> 70%). The product containing amine fluoride still had > 45% of free fluoride, the sodium monofluorophosphate products however had 10% or less of free fluoride.

  11. Characteristics of the turbulence in the stable boundary layer over complex terrain of the Loess Plateau, China

    Science.gov (United States)

    Liang, J.; Zhang, L.; Yuan, G.

    2017-12-01

    Accurate determination of surface turbulent fluxes in a stable boundary layer is of great practical importance in weather prediction and climate simulations, as well as applications related to air pollution. To gain an insight into the characteristics of turbulence in a stable boundary layer over the complex terrain of the Loess Plateau, we analyzed the data from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). We proposed a method to identify and efficiently isolate nonstationary motions from turbulence series, and examined the characteristics of nonstationary motions (nonstationary motions refer to gusty events on a greater scale than local shear-generated turbulence). The occurrence frequency of nonstationary motions was found to depend on the mean flow, being more frequent in weak wind conditions and vanishing when the wind speed, U, was greater than 3.0 m s-1. When U exceeded the threshold value of 1.0 m s-1 for the gradient Richardson number Ri ≤ 0.3 and 1.5 m s-1 for Ri > 0.3, local shear-generated turbulence depended systematically on U with an average rate of 0.05 U. However, for the weak wind condition, neither the mean wind speed nor the stability was an important factor for local turbulence. Under the weak wind stable condition, affected by topography-induced nonstationary motions, the local turbulence was anisotropic with a strong horizontal fluctuation and a weak vertical fluctuation, resulting in weakened heat mixing in the vertical direction and stronger un-closure of energy. These findings accessed the validity of similarity theory in the stable boundary layer over complex terrain, and revealed one reason for the stronger un-closure of energy in the night.

  12. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse......, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. CONCLUSIONS: This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam...

  13. A stable gold(i)-enyne species obtained by alkyne carboauration in a complex rearrangement.

    Science.gov (United States)

    Cámara, Jéssica; Blanco, M Carmen; Laguna, Antonio; Naumov, Panče; Gimeno, M Concepción

    2017-08-15

    An unprecedented tetranuclear gold derivative with unusual gold-enyne moieties is prepared by a mild and neat rearrangement of a dinuclear gold complex with a bridging bis(diphenylphosphino)alkyne and terminal alkynyl ligands. The complex originates as a consequence of an intramolecular addition of the AuC[triple bond, length as m-dash]CTol fragment to the internal diphosphine triple bond Ph 2 PC[triple bond, length as m-dash]CPPh 2 . The crystal structure of the tetranuclear complex shows a dinuclear metallacycle with a very short AuAu bond interaction and bridging phosphino-enyne ligands. This disposition clearly stabilises the elusive vinyl gold species omnipresent as intermediates in gold-catalysed reactions.

  14. Destruction of chemical warfare agent simulants by air and moisture stable metal NHC complexes.

    Science.gov (United States)

    Weetman, Catherine; Notman, Stuart; Arnold, Polly L

    2018-02-20

    The cooperative effect of both NHC and metal centre has been found to destroy chemical warfare agent (CWA) simulants. Choice of both the metal and NHC is key to these transformations as simple, monodentate N-heterocyclic carbenes in combination with silver or vanadium can promote stoichiometric destruction, whilst bidentate, aryloxide-tethered NHC complexes of silver and alkali metals promote breakdown under mild heating. Iron-NHC complexes generated in situ are competent catalysts for the destruction of each of the three targetted CWA simulants.

  15. Spectrophotometric determination of fluoride in drinking water using ...

    African Journals Online (AJOL)

    A sensitive spectrophotometric determination of fluoride in drinking water has been developed using aluminium complexes of triphenylmethane dyes (chrome azurol B and malachite green) as spectrophotometric reagents. The method allowed a reliable determination of fluoride in the range of 0.5–4.0 mg·l-1 for chrome ...

  16. The promyelocytic leukemia gene product (PML) forms stable complexes with the retinoblastoma protein

    DEFF Research Database (Denmark)

    Alcalay, M; Tomassoni, L; Colombo, E

    1998-01-01

    by the expression of PML-RAR alpha. We report that PML colocalizes with the nonphosphorylated fraction of the retinoblastoma protein (pRB) within nuclear bodies and that pRB is delocalized by PML-RAR alpha expression. Both PML and PML-RAR alpha form complexes with the nonphosphorylated form of pRB in vivo...

  17. Stable dipole solitons and soliton complexes in the nonlinear Schrödinger equation with periodically modulated nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, M. E., E-mail: gloriouslair@gmail.com, E-mail: galfimov@yahoo.com; Alfimov, G. L., E-mail: gloriouslair@gmail.com, E-mail: galfimov@yahoo.com [National Research University of Electronic Technology MIET, Zelenograd, Moscow 124498 (Russian Federation); Malomed, Boris A., E-mail: malomed@post.tau.ac.il [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Laboratory of Nonlinear-Optical Informatics, ITMO University, St. Petersburg 197101 (Russian Federation)

    2016-07-15

    We develop a general classification of the infinite number of families of solitons and soliton complexes in the one-dimensional Gross-Pitaevskii/nonlinear Schrödinger equation with a nonlinear lattice pseudopotential, i.e., periodically modulated coefficient in front of the cubic term, which takes both positive and negative local values. This model finds direct implementations in atomic Bose-Einstein condensates and nonlinear optics. The most essential finding is the existence of two branches of dipole solitons (DSs), which feature an antisymmetric shape, being essentially squeezed into a single cell of the nonlinear lattice. This soliton species was not previously considered in nonlinear lattices. We demonstrate that one branch of the DS family (namely, which obeys the Vakhitov-Kolokolov criterion) is stable, while unstable DSs spontaneously transform into stable fundamental solitons (FSs). The results are obtained in numerical and approximate analytical forms, the latter based on the variational approximation. Some stable bound states of FSs are found too.

  18. Evolutionary Search for Globally Optimal Stable Multicycles in Complex Systems with Inventory Couplings

    Directory of Open Access Journals (Sweden)

    M. Skowron

    2009-01-01

    Full Text Available This note is devoted to multiperiodically operated complex system with inventory couplings transferring waste products from some subsystems as useful components to other subsystems. The flexibility of the inventory couplings is used to force each of the subsystems with its own period and to exploit its particular dynamic properties. This enhances the performance of the complex system endowed with many recycling loops, which reduce the amount of waste products endangering the natural environment. The subsystems are characterized by generalized populations composed of the individuals (the cycles, each of them encompasses its period, its initial state, its local control, and its inventory interaction. An evolutionary optimization algorithm employing such generalized populations coordinated on the basis of the inventory interaction constraints is developed. It includes the stability requirements imposed on the cyclic control processes connected with particular subsystems. The algorithm proposed is applied to the global multiperiodic optimization of some interconnected chemical production processes.

  19. Fluoride geochemistry of thermal waters in Yellowstone National Park: I. Aqueous fluoride speciation

    Science.gov (United States)

    Deng, Y.; Nordstrom, D. Kirk; McCleskey, R. Blaine

    2011-01-01

    Thermal water samples from Yellowstone National Park (YNP) have a wide range of pH (1–10), temperature, and high concentrations of fluoride (up to 50 mg/l). High fluoride concentrations are found in waters with field pH higher than 6 (except those in Crater Hills) and temperatures higher than 50 °C based on data from more than 750 water samples covering most thermal areas in YNP from 1975 to 2008. In this study, more than 140 water samples from YNP collected in 2006–2009 were analyzed for free-fluoride activity by ion-selective electrode (ISE) method as an independent check on the reliability of fluoride speciation calculations. The free to total fluoride concentration ratio ranged from 99% at high pH. The wide range in fluoride activity can be explained by strong complexing with H+ and Al3+ under acidic conditions and lack of complexing under basic conditions. Differences between the free-fluoride activities calculated with the WATEQ4F code and those measured by ISE were within 0.3–30% for more than 90% of samples at or above 10−6 molar, providing corroboration for chemical speciation models for a wide range of pH and chemistry of YNP thermal waters. Calculated speciation results show that free fluoride, F−, and major complexes (HF(aq)0">HF(aq)0, AlF2+, AlF2+">AlF2+and AlF30">AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-">AlF4-, FeF2+, FeF2+">FeF2+, MgF+ and BF2(OH)2-">BF2(OH)2- may comprise 1–10% when the concentrations of the appropriate components are high. According to the simulation results by PHREEQC and calculated results, the ratio of main fluoride species to total fluoride varies as a function of pH and the concentrations and ratios of F and Al.

  20. Fluoride varnishes and enamel caries

    NARCIS (Netherlands)

    Bruyn, Hugo de

    1987-01-01

    Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical

  1. Rapid presumptive identification of the Mycobacterium tuberculosis-bovis complex by radiometric determination of heat stable urease

    International Nuclear Information System (INIS)

    Gandy, J.H.; Pruden, E.L.; Cox, F.R.

    1983-01-01

    Simple and rapid Bactec methodologies for the determination of neat (unaltered) and heat stable urease activity of mycobacteria are presented. Clinical isolates (63) and stock cultures (32)--consisting of: M. tuberculosis (19), M. bovis (5), M. kansasii (15), M. marinum (4), M. simiae (3), M. scrofulaceum (16), M. gordonae (6), M. szulgai (6), M. flavescens (1), M. gastri (1), M. intracellulare (6), M. fortuitum-chelonei complex (12), and M. smegmatis (1)--were tested for neat urease activity by Bactec radiometry. Mycobacterial isolates (50-100 mg wet weight) were incubated at 35 degrees C for 30 minutes with microCi14C-urea. Urease-positive mycobacteria gave Bactec growth index (GI) values greater than 100 units, whereas urease-negative species gave values less than 10 GI units. Eighty-three isolates possessing neat urease activity were heated at 80 degrees C for 30 minutes followed by incubation at 35 degrees C for 30 minutes with 1 microCi14C-urea. Mycobacterium tuberculosis-bovis complex demonstrated heat-stable urease activity (GI more than 130 units) and could be distinguished from mycobacteria other than tuberculosis (MOTT), which gave GI values equal to or less than 40 units

  2. Raf-1 forms a stable complex with Mek1 and activates Mek1 by serine phosphorylation.

    OpenAIRE

    Huang, W; Alessandrini, A; Crews, C M; Erikson, R L

    1993-01-01

    Recombinant Mek1 and Raf-1 proteins produced in Sf9 cells undergo a tight association both in vivo and in vitro, which apparently does not depend on additional factors or the kinase activity of Mek1 or Raf-1. The complex can be disrupted by two polyclonal antibodies raised against Raf-1 peptides. Coinfection with Raf-1 activates Mek1 > 150-fold, and coinfection with Raf-1 and Mek1 activates Erk1 approximately 90-fold. The activation of Mek1 by Raf-1 involves only serine phosphorylation, which...

  3. fluoride iontophoresis versus topical fluoride application

    African Journals Online (AJOL)

    The process of influencing ionic motion by electrical cur- rent has been termed iontophoresis, electophoresis ... In iontophroresis, it is believed that fluoride ion is elec- trically driven deeper into the dentinal tubules. ..... the hydraulic conductance of Human Dentin, in vitro, J. Dent. Res. 1981; 60:686698. 6. Gillam D G. Clinical ...

  4. Integration as the basis of stable and dynamic development of enterprises in agroindustrial complex

    Directory of Open Access Journals (Sweden)

    Petr Ivanovich Ogorodnikov

    2011-12-01

    Full Text Available Formation of market relations in Russian economy generates an objective need to address a number of problems in the relationship between agroundustrial complex organizations in connection with privatization, liberalization of prices and imbalances in the existing inter-industry production and economic relations that negatively affect the results of their economic activities. Because of the flagrant violations of the replenishment process, a diverse range of connections and relationships between producers and processors was broken. The major direction of lifting agricultural economy in this situation is the development of cooperatives and agroindustrial integration. In addition, the formation of large integrated complexes demonstrates high efficiency and rapid development, which is the basis of agroindustrial sector in many developed countries. The increase of competition forces business entities to combine capabilities and mutually beneficial cooperation in the struggle for the strengthening of market positions. Thus, increasing the degree of integration in the agricultural sector helps to get out of the protracted crisis and move more quickly to the innovations.

  5. Identifying apparent local stable isotope equilibrium in a complex non-equilibrium system.

    Science.gov (United States)

    He, Yuyang; Cao, Xiaobin; Wang, Jianwei; Bao, Huiming

    2018-02-28

    Although being out of equilibrium, biomolecules in organisms have the potential to approach isotope equilibrium locally because enzymatic reactions are intrinsically reversible. A rigorous approach that can describe isotope distribution among biomolecules and their apparent deviation from equilibrium state is lacking, however. Applying the concept of distance matrix in graph theory, we propose that apparent local isotope equilibrium among a subset of biomolecules can be assessed using an apparent fractionation difference (|Δα|) matrix, in which the differences between the observed isotope composition (δ') and the calculated equilibrium fractionation factor (1000lnβ) can be more rigorously evaluated than by using a previous approach for multiple biomolecules. We tested our |Δα| matrix approach by re-analyzing published data of different amino acids (AAs) in potato and in green alga. Our re-analysis shows that biosynthesis pathways could be the reason for an apparently close-to-equilibrium relationship inside AA families in potato leaves. Different biosynthesis/degradation pathways in tubers may have led to the observed isotope distribution difference between potato leaves and tubers. The analysis of data from green algae does not support the conclusion that AAs are further from equilibrium in glucose-cultured green algae than in the autotrophic ones. Application of the |Δα| matrix can help us to locate potential reversible reactions or reaction networks in a complex system such as a metabolic system. The same approach can be broadly applied to all complex systems that have multiple components, e.g. geochemical or atmospheric systems of early Earth or other planets. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Letter Report: Stable Hydrogen and Oxygen Isotope Analysis of B-Complex Perched Water Samples

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Brady D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Moran, James J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nims, Megan K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Saunders, Danielle L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-04-13

    Fine-grained sediments associated with the Cold Creek Unit at Hanford have caused the formation of a perched water aquifer in the deep vadose zone at the B Complex area, which includes waste sites in the 200-DV-1 Operable Unit and the single-shell tank farms in Waste Management Area B-BX-BY. High levels of contaminants, such as uranium, technetium-99, and nitrate, make this aquifer a continuing source of contamination for the groundwater located a few meters below the perched zone. Analysis of deuterium (2H) and 18-oxygen (18O) of nine perched water samples from three different wells was performed. Samples represent time points from hydraulic tests performed on the perched aquifer using the three wells. The isotope analyses showed that the perched water had δ2H and δ18O ratios consistent with the regional meteoric water line, indicating that local precipitation events at the Hanford site likely account for recharge of the perched water aquifer. Data from the isotope analysis can be used along with pumping and recovery data to help understand the perched water dynamics related to aquifer size and hydraulic control of the aquifer in the future.

  7. Preparation of bromine fluoride

    International Nuclear Information System (INIS)

    Domange, Pr; Duflo, J.

    1958-05-01

    This note addresses the preparation of bromine fluoride. It indicates the implemented process for the reaction, used products (fluorine and bromine), and column characteristics. It describes the operating mode. Apparatus drawing is provided

  8. Uranium fluorides analysis. Titanium spectrophotometric determination

    International Nuclear Information System (INIS)

    Anon.

    Titanium determination in uranium hexafluoride in the range 0.7 to 100 microgrammes after transformation of uranium fluoride in sulfate. Titanium is separated by extraction with N-benzoylphenylhydroxylamine, reextracted by hydrochloric-hydrofluoric acid. The complex titanium-N-benzoylphenylhydroxylamine is extracted by chloroform. Spectrophotometric determination at 400 nm [fr

  9. The Enhanced Intramolecular Energy Transfer and Strengthened ff Luminescence of a Stable Helical Eu Complex in Ionic Liquids.

    Science.gov (United States)

    Hasegawa, Yuki; Ishii, Ayumi; Inazuka, Yudai; Yajima, Naho; Kawaguchi, Shogo; Sugimoto, Kunihisa; Hasegawa, Miki

    2018-01-24

    The luminescence of a Eu complex (EuL) is enhanced by stabilization of the coordination structure in highly viscous ionic liquids. The EuL was found to maintain a stable single helical structure both in organic solvents and in the ionic liquids [BMIM][PF₆] and [EMIM][PF₆]. A colorless solution of EuL dissolved in [BMIM][PF₆] exhibits bright red luminescence with a quantum yield of 32.3%, a value that is much higher than that in acetonitrile (12%). Estimated rate constants for the energy relaxation pathway indicate that the energy transfer efficiency is enhanced in [BMIM][PF₆] as a result of the suppression of molecular fluctuations in the ligands. Additionally, a highly luminescent helical structure is preserved in [EMIM][PF₆] up to 120 °C.

  10. Human Cytomegalovirus gH/gL Forms a Stable Complex with the Fusion Protein gB in Virions.

    Directory of Open Access Journals (Sweden)

    Adam L Vanarsdall

    2016-04-01

    Full Text Available Human cytomegalovirus (HCMV is a ubiquitous virus that is a major pathogen in newborns and immunocompromised or immunosuppressed patients. HCMV infects a wide variety of cell types using distinct entry pathways that involve different forms of the gH/gL glycoprotein: gH/gL/gO and gH/gL/UL128-131 as well as the viral fusion glycoprotein, gB. However, the minimal or core fusion machinery (sufficient for cell-cell fusion is just gH/gL and gB. Here, we demonstrate that HCMV gB and gH/gL form a stable complex early after their synthesis and in the absence of other viral proteins. gH/gL can interact with gB mutants that are unable to mediate cell-cell fusion. gB-gH/gL complexes included as much as 16-50% of the total gH/gL in HCMV virus particles. In contrast, only small amounts of gH/gL/gO and gH/gL/UL128-131 complexes were found associated with gB. All herpesviruses express gB and gH/gL molecules and most models describing herpesvirus entry suggest that gH/gL interacts with gB to mediate membrane fusion, although there is no direct evidence for this. For herpes simplex virus (HSV-1 it has been suggested that after receptor binding gH/gL binds to gB either just before, or coincident with membrane fusion. Therefore, our results have major implications for these models, demonstrating that HCMV gB and gH/gL forms stable gB-gH/gL complexes that are incorporated virions without receptor binding or membrane fusion. Moreover, our data is the best support to date for the proposal that gH/gL interacts with gB.

  11. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...

  12. Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

    Data.gov (United States)

    U.S. Department of Health & Human Services — 2000-2014 Water Fluoridation Statistics is a biennial report of the percentage and number of people receiving fluoridated water from 2000 through 2014, originally...

  13. Water Fluoridation Statistics - Percent of PWS population receiving fluoridated water

    Data.gov (United States)

    U.S. Department of Health & Human Services — 2000-2014. Water Fluoridation Statistics is a biennial report of the percentage and number of people receiving fluoridated water from 2000 through 2014, originally...

  14. Synthesis of 2-deoxy-2,2-difluoro-α-maltosyl fluoride and its X-ray structure in complex with Streptomyces coelicolor GlgEI-V279S

    Energy Technology Data Exchange (ETDEWEB)

    Thanna, Sandeep; Lindenberger, Jared J.; Gaitonde, Vishwanath V.; Ronning, Donald R.; Sucheck, Steven J. (Toledo)

    2015-06-05

    Streptomyces coelicolor (Sco) GlgEI is a glycoside hydrolase involved in α-glucan biosynthesis and can be used as a model enzyme for structure-based inhibitor design targeting Mycobacterium tuberculosis (Mtb) GlgE. The latter is a genetically validated drug target for the development of anti-Tuberculosis (TB) treatments. Inhibition of Mtb GlgE results in a lethal buildup of the GlgE substrate maltose-1-phosphate (M1P). However, Mtb GlgE is difficult to crystallize and affords lower resolution X-ray structures. Sco GlgEI-V279S on the other hand crystallizes readily, produces high resolution X-ray data, and has active site topology identical to Mtb GlgE. We report the X-ray structure of Sco GlgEI-V279S in complex with 2-deoxy-2,2-difluoro-α-maltosyl fluoride (α-MTF, 5) at 2.3 Å resolution. α-MTF was designed as a non-hydrolysable mimic of M1P to probe the active site of GlgE1 prior to covalent bond formation without disruption of catalytic residues. The α-MTF complex revealed hydrogen bonding between Glu423 and the C1F which provides evidence that Glu423 functions as proton donor during catalysis. Further, hydrogen bonding between Arg392 and the axial C2 difluoromethylene moiety of α-MTF was observed suggesting that the C2 position tolerates substitution with hydrogen bond acceptors. The key step in the synthesis of α-MDF was transformation of peracetylated 2-fluoro-maltal 1 into peracetylated 2,2-difluoro-α-maltosyl fluoride 2 in a single step via the use of Selectfluor®

  15. Private Well Water and Fluoride

    Science.gov (United States)

    ... than the recommended level of fluoride for preventing tooth decay? The recommended fluoride level in drinking water for ... are higher than the recommended level for preventing tooth decay? In some regions in the United States, community ...

  16. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    Science.gov (United States)

    Barton, C.J.; Grimes, W.R.

    1960-01-01

    Molten-salt reactor fuel compositions consisting of mixtures of fluoride salts are reported. In its broadest form, the composition contains an alkali fluoride such as sodium fluoride, zirconium tetrafluoride, and a uranium fluoride, the latter being the tetrafluoride or trifluoride or a mixture of the two. An outstanding property of these fuel compositions is a high coeffieient of thermal expansion which provides a negative temperature coefficient of reactivity in reactors in which they are used.

  17. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p...

  18. Fluoride resistance in Streptococcus mutans

    NARCIS (Netherlands)

    Liao, Ying

    2017-01-01

    Fluoride has been used as the most effective anti-caries agent for over five decades. It functions not only on the dental hard tissues, but also as an antimicrobial agent. It is known that oral bacteria are able to develop resistance to fluoride, which may affect the effectiveness of fluoride in

  19. Urinary fluoride excretion after application of fluoride varnish and use of fluoride toothpaste in young children

    DEFF Research Database (Denmark)

    Lockner, Frida; Twetman, Svante; Stecksén-Blicks, Christina

    2017-01-01

    BACKGROUND: The efficacy and safety of combined use of topical fluoride products are essential issues that must be monitored. AIM: To assess urinary excretion of fluoride after application of two different dental varnishes containing 2.26% fluoride in 3- to 4-year-old children and to compare...... the levels with and without parallel use of fluoride toothpaste. DESIGN: Fifteen healthy children were enrolled to a randomized crossover trial that was performed in two parts: Part I with twice-daily tooth brushing with fluoride toothpaste and Part II with twice-daily brushing with a non-fluoride toothpaste....... After a 1-week run-in period, 0.1 mL of the two fluoride varnishes (Duraphat and Profluorid Varnish) was topically applied in a randomized order. Baseline and experimental urine was collected during 6-h periods. The fluoride content was determined with an ion-sensitive electrode. RESULTS...

  20. Stable Isotope Evidence for a Complex Fluid Evolution of the Northwestern British Columbia Coast Ranges Related to Terrane Accretion

    Science.gov (United States)

    Moertle, J.; Holk, G. J.

    2015-12-01

    Stable isotope geochemistry reveals a complex fluid evolution for the Western Metamorphic Belt (WMB), Coast Ranges Batholith (CRB), Central Gneiss Complex (CGC) and Coast Ranges Megalineament (CRM). These fluids are a product of a complex tectonic history related to terrane accretion that includes oblique convergence, metamorphism, magmatism, and orogenic collapse. From W-to-E, these fluid systems are as follows. High-pressure greenschist-to-amphibolite facies metasedimentary rocks of the WMB record variable mineral δD (-61 to -104‰) and δ18O (e.g., quartz +9.6 to +13.4‰) values with multiple minerals in apparent isotopic equilibrium (T ~ 450-550°C) suggest a low W/R system dominated by metamorphic fluids. Variable and non-equilibrium δD (-53 to -143‰) and δ18O (e.g., biotite +2.3 to +5.3‰) values from diorites of the Quottoon pluton affected by the ductile CRM suggest a complex evolution that involved both metamorphic and meteoric-hydrothermal fluids in this dextral shear zone; these results differ from those 300 km along strike to the north that documented only metamorphic fluids in the CRM (Goldfarb et al., 1988). Our data and those of Magaritz and Taylor (1976) from granulite facies metasediments of the CGC and plutons of the western CRB reveal homogeneous δD values (-62 to -78‰) and a restricted range of δ18O values (e.g., quartz +8.5 to +11.5‰) with all minerals in equilibrium at T > 570°C indicate a system dominated by magmatic fluids. Calculated whole-rock δ18O values (~ +7‰) for the Quottoon pluton and CRB intrusive rocks suggest a mantle origin for these magmas. Reinterpretation of very low δD (< -150‰) and quartz-feldspar δ18O pairs that display extreme disequilibrium (feldspar δ18O values as low as -5‰) from the Ponder pluton, eastern CRB, and Hazelton Group point reveals that the major meteoric-hydrothermal system that affected these rocks was related to Eocene detachment faulting along the Shames Lake fault system, a

  1. Crystal Structures of Beryllium Fluoride-Free and Beryllium Fluoride-Bound CheY in Complex with the Conserved C-Terminal Peptide of CheZ Reveal Dual Binding Modes Specific to CheY Conformation

    Energy Technology Data Exchange (ETDEWEB)

    Guhaniyogi,J.; Robinson, V.; Stock, A.

    2006-01-01

    Chemotaxis, the environment-specific swimming behavior of a bacterial cell is controlled by flagellar rotation. The steady-state level of the phosphorylated or activated form of the response regulator CheY dictates the direction of flagellar rotation. CheY phosphorylation is regulated by a fine equilibrium of three phosphotransfer activities: phosphorylation by the kinase CheA, its auto-dephosphorylation and dephosphorylation by its phosphatase CheZ. Efficient dephosphorylation of CheY by CheZ requires two spatially distinct protein-protein contacts: tethering of the two proteins to each other and formation of an active site for dephosphorylation. The former involves interaction of phosphorylated CheY with the small highly conserved C-terminal helix of CheZ (CheZ{sub C}), an indispensable structural component of the functional CheZ protein. To understand how the CheZ{sub C} helix, representing less than 10% of the full-length protein, ascertains molecular specificity of binding to CheY, we have determined crystal structures of CheY in complex with a synthetic peptide corresponding to 15 C-terminal residues of CheZ (CheZ{sub 200-214}) at resolutions ranging from 2.0 Angstroms to 2.3 Angstroms. These structures provide a detailed view of the CheZC peptide interaction both in the presence and absence of the phosphoryl analog, BeF{sub 3}{sup -}. Our studies reveal that two different modes of binding the CheZ{sub 200-214} peptide are dictated by the conformational state of CheY in the complex. Our structures suggest that the CheZ{sub C} helix binds to a 'meta-active' conformation of inactive CheY and it does so in an orientation that is distinct from the one in which it binds activated CheY. Our dual binding mode hypothesis provides implications for reverse information flow in CheY and extends previous observations on inherent resilience in CheY-like signaling domains.

  2. Selective Complexation of Cyanide and Fluoride Ions with Ammonium Boranes: A Theoretical Study on Sensing Mechanism Involving Intramolecular Charge Transfer and Configurational Changes.

    Science.gov (United States)

    Bhat, Haamid R; Jha, Prakash C

    2017-05-18

    The anion binding selectivity and the recognition mechanism of two isomeric boranes, namely, 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([p-(Mes 2 B)C 6 H 4 (NMe 3 )] + , 1, where "Mes" represents mesitylene and "Me" represents methyl) and 2-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([o-(Mes 2 B)C 6 H 4 (NMe 3 )] + , 2) has been investigated using density functional theory (DFT) and time dependent-density functional theory (TD-DFT) methods. Natural population analysis indicates that the central boron atoms in 1 and 2 are the most active centers for nucleophilic addition of anions. The negative magnitude of free energy changes (ΔG) reveals that out of CN - , F - , Cl - , Br - , NO 3 - , and HSO 4 - only the binding of CN - and F - with 1 and 2 is thermodynamically feasible and spontaneous. In addition, the calculated binding energies reveal that the CN - is showing lesser binding affinity than F - both with 1 and 2, while other ions, viz. NO 3 - , HSO 4 - , Br - , and Cl - , either do not bind at all or show very insignificant binding energy. The first excited states (S 1 ) of 1 and 2 are shown to be the local excited states with π → σ* transition by frontier molecular orbital analysis, whereas fourth excited states (S 4 ) of 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline cyanide ([p-(Mes 2 B)C 6 H 4 (NMe 3 )] CN, 1CN, the cyano form of 1) and 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline fluoride ([p-(Mes 2 B)C 6 H 4 (NMe 3 )] F, 1F, the fluoro form of 1) and fifth excited state (S 5 ) of 2-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline fluoride ([o-(Mes 2 B)C 6 H 4 (NMe 3 )] F, 2F, the fluoro form of 2) are charge separation states that are found to be responsible for the intramolecular charge transfer (ICT) process. The synergistic effect of ICT and partial configuration changes induce fluorescence quenching in 1CN, 1F, and 2F after a significant internal conversion (IC) from S 4 and

  3. Quantitative Determination of Lattice Fluoride Effects on the Solubility and Crystallinity of Carbonated Apatites with Incorporated Fluoride

    Science.gov (United States)

    Yan, Guang; Moribe, Kunikazu; Otsuka, Makoto; Papangkorn, Kongnara; Higuchi, William I.

    2013-01-01

    The purpose of this study was to evaluate quantitatively the effects of fluoride on the solubility and crystallinity of carbonated apatites (CAPs) after its incorporation into the crystal lattice using the metastable equilibrium solubility (MES) distribution method. Fluoride incorporated CAPs (F-CAPs) of two different carbonate levels (3% and 5%) and fluoride contents from 0 to 20,000 μg/g were synthesized. X-ray diffraction experiments and Rietveld analysis were conducted to obtain crystallite microstrain and unit cell parameters. Acetate buffer MES solution media were prepared at two solution fluoride concentrations (0.2 mg/L and 2.0 mg/L) and at two pHs (5.0 and 5.7). The unit cell a-axis values of the F-CAPs were found to decrease as the fluoride content increased; consistent with the fluoride being incorporated into the crystal lattice. The fluoride concentrations in the MES solution media were high enough to provide a “swamping” effect such that the fluoride released from the F-CAPs during dissolution was minimal in changing the solution fluoride concentration. Employing the MES distribution superposition method, it was shown that the surface complex possessing the fluorapatite (FAP) stoichiometry (Ca10(PO4)6F2) accounted for the MES distribution behavior of all experiments. In addition, the mean pIFAP [the value of −log(aca 10PO46aF2) calculated from ionic activity product based on FAP stoichiometry of the MES dissolution media in which 50% of the F-CAP had dissolved] correlated well with the crystallite microstrain parameters of the F-CAPs. The incorporated fluoride in the F-CAPs showed only modest effects on F-CAP crystallinity and solubility. PMID:23235353

  4. Exraction and separation of CERIUM(IV/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    Directory of Open Access Journals (Sweden)

    Y. Li

    2014-07-01

    Full Text Available In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  5. Small Molecule Fluoride Toxicity Agonists

    Science.gov (United States)

    Nelson1, James W.; Plummer, Mark S.; Blount, Kenneth F.; Ames, Tyler D.; Breaker, Ronald R.

    2015-01-01

    SUMMARY Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch-reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. PMID:25910244

  6. Salt fluoridation and oral health

    Directory of Open Access Journals (Sweden)

    Thomas M. Marthaler

    2013-11-01

    Full Text Available The aim of this paper is to make known the potential of fluoridated salt in community oral health programs, particularly in South Eastern Europe. Since 1922, the addition of iodine to salt has been successful in Switzerland. Goiter is virtually extinct. By 1945, the cariesprotective effect of fluorides was well established. Based on the success of water fluoridation, a gynecologist started adding of fluoride to salt. The sale of fluoridated salt began in 1956 in the Swiss Canton of Zurich, and several other cantons followed suit. Studies initiated in the early seventies showed that fluoride, when added to salt, inhibits dental caries. The addition of fluoride to salt for human consumption was officially authorized in 1980-82. In Switzerland 85% of domestic salt consumed is fluoridated and 67% in Germany. Salt fluoridation schemes are reaching more than one hundred million in Mexico, Colombia, Peru and Cuba. The cost of salt fluoridation is very low, within 0.02 and 0.05 € per year and capita. Children and adults of the low socio-economic strata tend to have substantially more untreated caries than higher strata. Salt fluoridation is by far the cheapest method for improving oral health. Conclusions. Salt fluoridation has cariostatic potential like water fluoridation (caries reductions up to 50%. In Europe, meaningful percentages of users have been attained only in Germany (67% and Switzerland (85%. In Latin America, there are more than 100 million users, and several countries have arrived at coverage of 90 to 99%. Salt fluoridation is by far the cheapest method of caries prevention, and billions of people throughout the world could benefit from this method.

  7. Salt fluoridation and oral health.

    Science.gov (United States)

    Marthaler, Thomas M

    2013-11-01

    The aim of this paper is to make known the potential of fluoridated salt in community oral health programs, particularly in South Eastern Europe. Since 1922, the addition of iodine to salt has been successful in Switzerland. Goiter is virtually extinct. By 1945, the caries-protective effect of fluorides was well established. Based on the success of water fluoridation, a gynecologist started adding of fluoride to salt. The sale of fluoridated salt began in 1956 in the Swiss Canton of Zurich, and several other cantons followed suit. Studies initiated in the early seventies showed that fluoride, when added to salt, inhibits dental caries. The addition of fluoride to salt for human consumption was officially authorized in 1980-82. In Switzerland 85% of domestic salt consumed is fluoridated and 67% in Germany. Salt fluoridation schemes are reaching more than one hundred million in Mexico, Colombia, Peru and Cuba. The cost of salt fluoridation is very low, within 0.02 and 0.05 € per year and capita. Children and adults of the low socio-economic strata tend to have substantially more untreated caries than higher strata. Salt fluoridation is by far the cheapest method for improving oral health. Salt fluoridation has cariostatic potential like water fluoridation (caries reductions up to 50%). In Europe, meaningful percentages of users have been attained only in Germany (67%) and Switzerland (85%). In Latin America, there are more than 100 million users, and several countries have arrived at coverage of 90 to 99%. Salt fluoridation is by far the cheapest method of caries prevention, and billions of people throughout the world could benefit from this method. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

  8. Thermodynamic stability of complexes of BF3, PF5 and AsF5 with chlorine fluorides, oxyfluorides, and related compounds

    International Nuclear Information System (INIS)

    Trowbridge, L.D.

    1996-07-01

    The recent discovery of solid, water sensitive, arsenic-containing deposits in auxiliary process piping in the PGDP led to a search for explanations that could account for such accumulated material. A plausible explanation for the deposits is the formation of complexes of AsF 5 with one or more gases that may have been present as a result of cascade equipment cleanup activities. A literature search was performed. The target of the search was literature that would provide information on the dissociation pressure of complexes of AsF 5 or its hydrolysis products with any gases that may be (at least intermittently) present in the cascade location where the deposits were found. While the precise information sought (namely reliable, accurate dissociation pressures of such complexes at cascade temperatures) was not found in the detail desired. other information on these or similar complexes was obtained which permits prediction of the conditions under which the complexes might form, dissociate, or migrate, and how they might behave in the presence of atmospheric moisture. Information was gathered on potential AsF 5 complexes with ClF, ClF 3 , ClF 5 , ClF 3 O, ClO 2 F, and ClO 3 F. Information was also collected on many other related complexes as it was encountered, particularly for series of complexes which could assist in predicting chemical trends. Thermodynamic analysis and property estimation methods have been used to generate provisional estimates of the dissociation pressures of the two complexes ClF 3 *AsF 5 and ClO 2 F*AsF 5 . In addition, several hydrolysis species have been identified, and stability properties of the most relevant such complex (H 3 O*AsF 6 ) have similarly been estimated. While the predicted dissociation pressures are somewhat uncertain. they do lead to a tentative picture of the formation and behavior of such complexes in a cascade cleanup environment

  9. Pr5F[SiO4]2[SeO3]3. Another complex fluoride oxosilicate oxoselenate(IV)

    International Nuclear Information System (INIS)

    Lipp, Christian; Burns, Peter C.; Schleid, Thomas

    2012-01-01

    During attempts to synthesize lanthanoid(III) fluoride oxoselenates(IV) with the simple composition MF[SeO 3 ], not only Pr 3 F[SeO 3 ] 4 , but also Pr 5 F[SiO 4 ] 2 [SeO 3 ] 3 appeared as pale green crystalline by-products in the case of praseodymium. Pr 5 F[SiO 4 ] 2 [SeO 3 ] 3 crystallizes triclinically in space group P anti 1 (no. 2) with a = 701.14(5), b = 982.68(7), c = 1286.79(9) pm, α = 70.552(3), β = 76.904(3), γ = 69.417(3) and Z = 2. The five crystallographically different Pr 3+ cations on the general positions 2i show coordination numbers of eight and nine. [(Pr1)O 8 ] 13- and [(Pr2)O 8 ] 13- polyhedra are connected to anti 1{[(Pr1, 2) 2 O 12 ] 18- } chains along the [100] direction. [(Pr3)O 7 F] 12- , [(Pr4)O 8 F] 14- and [(Pr4)O 8 F] 14- polyhedra generate [F(Pr3, 4, 5) 3 O 19 ] 30- units about their central F - anion in triangular Pr 3+ coordination. These units form anti 1{[F(Pr3, 4, 5) 3 O 16 ] 24- } strands, again running parallel to [100]. Their alternating connection with the anti 1{[(Pr1, 2) 2 O 12 ] 18- } chains results in anti 1{[Pr 5 O 20 F] 26- } sheets parallel to the (001) plane. Like in the already known related compound Er 3 F[SiO 4 ][SeO 3 ] 2 , a three-dimensional network anti 1{[Pr 5 O 17 F] 20- } is achieved without the contribution of both the tetravalent silicon and selenium components. However, two Si 4+ and three Se 4+ cations forming tetrahedral [SiO 4 ] 4- and ψ 1 -tetrahedral [SeO 3 ] 2- units with all O 2- anions guarantee the charge balance. The formation of Pr 5 F[SiO 4 ] 2 [SeO 3 ] 3 was observed when praseodymium sesquioxide (Pr 2 O 3 : in-situ produced from Pr and Pr 6 O 11 in a molar ratio of 3 / 11 : 4 / 11 ), praseodymium trifluoride (PrF 3 ) and selenium dioxide (SeO 2 ) in 1:1:3 molar ratios were reacted with CsBr as fluxing agent for five days at 750 C in evacuated fused silica (SiO 2 ) ampoules. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Fluoride removal from brackish groundwater by direct contact membrane distillation.

    Science.gov (United States)

    Hou, D Y; Wang, J; Wang, B Q; Luan, Z K; Sun, X C; Ren, X J

    2010-01-01

    The direct contact membrane distillation (DCMD) applied for fluoride removal from brackish groundwater is presented. The self-prepared polyvinylidene fluoride membrane exhibited high rejection of inorganic salt solutes and a maximum permeate flux 35.6 kgm(-2) h(-1) was obtained. The feed concentration had no marked impact on the permeate flux and the rejection of fluoride. The precipitation of CaCO3 would clog the hollow fiber inlets and foul the membrane surface with the increase of concentration factor when natural groundwater was used directly as the feed, which resulted in a rapid decline of the module efficiency. This phenomenon was diminished by acidification of the feed. The experimental results showed that the permeate flux and the quality of obtained distillate kept stable before concentration factor reached 5.0 with the acidified groundwater as feed. The membrane module efficiency began to decline gradually when the feed continued to be concentrated, which can be mainly attributed to the formation of CaF2 deposits on the membrane surface. Finally, a 300 h continuous fluoride removal experiment on acidified groundwater was carried out with concentration factor at 4.0, the permeate flux kept stable and the permeate fluoride was not detected.

  11. Monitoring of fluoride in water samples using a smartphone

    International Nuclear Information System (INIS)

    Levin, Saurabh; Krishnan, Sunderrajan; Rajkumar, Samuel; Halery, Nischal; Balkunde, Pradeep

    2016-01-01

    In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0–2 mg l −1 . Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field. - Highlights: • Fluoride is an inorganic pollutant in ground water, affecting human health. • A colorimetric method for measurement of fluoride in drinking water with smartphone • Measurement is by mixing water with zirconyl xylenol orange complex reagent. • Results are comparable with laboratory-based ion selective fluoride electrode method.

  12. Monitoring of fluoride in water samples using a smartphone

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Saurabh [Akvo Foundation (Netherlands); Krishnan, Sunderrajan [INREM Foundation (India); Rajkumar, Samuel; Halery, Nischal; Balkunde, Pradeep [Akvo Foundation (Netherlands)

    2016-05-01

    In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0–2 mg l{sup −1}. Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field. - Highlights: • Fluoride is an inorganic pollutant in ground water, affecting human health. • A colorimetric method for measurement of fluoride in drinking water with smartphone • Measurement is by mixing water with zirconyl xylenol orange complex reagent. • Results are comparable with laboratory-based ion selective fluoride electrode method.

  13. Inert and stable erbium(III)-cored complexes based on metalloporphyrins bearing aryl-ether dendron for optical amplification: synthesis and emission enhancement

    International Nuclear Information System (INIS)

    Oh, Jae Buem; Kim, Yong Hee; Nah, Min Kook; Kim, Hwan Kyu

    2005-01-01

    We have developed novel inert and stable erbium (Er)(III)-cored complexes based on metalloporphyrins for optical amplification. The functionalized metalloporphyrin ligands have been designed and synthesized to provide enough coordination sites for the formation of inert and stable 9-coordinated Er(III)-cored complexes. Er 3+ ions were encapsulated by the metalloporphyrin ligands, such as Zn(II)- and Pt(II)-porphyrins. The near-infrared (IR) emission intensity of Er 3+ ion is much stronger in the Er(III)-cored complex based on Pt(II)-porphyrin than Er(III)-cored complex based on Zn(II)-porphyrin. Furthermore, we have incorporated a G2-aryl-ether functionalized dendron into the Er(III)-cored complex, yielding an Er(III)-cored dendrimer complex bearing the Pt(II)-porphyrin. The Er(III)-cored dendrimer complex shows the stronger near-IR emission intensity than the corresponding complex based on Pt(II)-porphyrin by seven times in solid state. The lifetimes of the emission band of Pt(II)-porphyrin ligands in the visible region were found to be 30 and 40 μs for the Er(III)-cored complex and the Er(III)-cored dendrimer complex based on Pt(II)-porphyrin in deoxygenated THF solution samples, respectively. Also, in both cases, the sensitized luminescence intensity is increased in deoxygenated solution. Therefore, it indicates that the energy transfer from the metalloporphyrins to Er 3+ ions takes places through the triplet state. In this paper, the synthesis and photophysical properties of novel Er(III)-cored complexes based on metalloporphyrins and Er(III)-cored dendrimer complex based on metalloporphyrin will be discussed

  14. Experimental and numerical study of atmospheric turbulence and dispersion in stable conditions and in near field at a complex site

    International Nuclear Information System (INIS)

    Wei, Xiao

    2016-01-01

    An experimental program has been designed in order to study pollutants dispersion at a complex site with a focus on stable conditions, which are still challenging for numerical modelling. This experimental program is being conducted at the SIRTA site in a southern suburb of Paris and consists in measuring, in near field, the turbulence and the pollutants dispersion. The aim of this program is to characterize the fine structure of turbulence and associated dispersion through high temporal and spatial resolution measurements. Then, these measurements allow to validate and improve the performance of CFD simulation for turbulence and dispersion in a heterogeneous field. The instrumental set up includes 12 ultrasonic anemometers measuring continuously wind velocity and temperature at 10 Hz, and 6 photo-ionization detectors (PIDs) measuring gas concentration at 50 Hz during tracer tests. Intensive observations periods (IOPs) with gas releases have been performed since March 2012.First of all, a detailed study of flow on the site is made, because it must be characterised and properly simulated before attempting to simulate the pollutants dispersion. This study is based on two years of continuous measurements and on measurements performed during IOPs. Turbulence strong anisotropy in the surface layer is characterized by calculating variances, integral length scales and power spectra of the three wind velocity components. Propagation of turbulent structures between sensors has been characterized with velocity correlations. Energy spectra show several slopes in different frequency regions. Also, data analyses show impact of terrain heterogeneity on the measurements. The forest to the north of experimental field modifies wind velocity and direction for a large northerly sector. It induces a strong directional wind shear and a wind deceleration below the forest height. Numerical simulations are carried out using the CFD code Code-Saturne in RANS mode with a standard κ

  15. Experimental and numerical study of atmospheric turbulence and dispersion in stable conditions and in near field at a complex site

    International Nuclear Information System (INIS)

    Wei, Xiao

    2016-01-01

    An experimental program has been designed in order to study pollutants dispersion at a complex site with a focus on stable conditions, which are still challenging for numerical modelling. This experimental program is being conducted at the SIRTA site in a southern suburb of Paris and consists in measuring, in near field, the turbulence and the pollutants dispersion. The aim of this program is to characterize the fine structure of turbulence and associated dispersion through high temporal and spatial resolution measurements. Then, these measurements allow to validate and improve the performance of CFD simulation for turbulence and dispersion in a heterogeneous field. The instrumental set up includes 12 ultrasonic anemometers measuring continuously wind velocity and temperature at 10 Hz, and 6 photo-ionization detectors (PIDs) measuring gas concentration at 50 Hz during tracer tests. Intensive observations periods (IOPs) with gas releases have been performed since March 2012. First of all, a detailed study of flow on the site is made, because it must be characterised and properly simulated before attempting to simulate the pollutants dispersion. This study is based on two years of continuous measurements and on measurements performed during IOPs. Turbulence strong anisotropy in the surface layer is characterized by calculating variances, integral length scales and power spectra of the three wind velocity components. Propagation of turbulent structures between sensors has been characterized with velocity correlations. Energy spectra show several slopes in different frequency regions. Also, data analyses show impact of terrain heterogeneity on the measurements. The forest to the north of the experimental field modifies wind velocity and direction for a large northerly sector. It induces a strong directional wind shear and a wind deceleration below the forest height. Numerical simulations are carried out using the CFD code, Code-Saturne, in RANS mode with a standard k

  16. Comparison of Fluoridated Miswak and Toothbrushing with Fluoridated Toothpaste on Plaque Removal and Fluoride Release.

    Science.gov (United States)

    Baeshen, Hosam; Salahuddin, Sabin; Dam, Robel; Zawawi, Khalid H; Birkhed, Dowen

    2017-04-01

    Dental caries and periodontal diseases are all induced by oral biofilm (dental plaque). This study was conducted to evaluate if fluoride-impregnated miswak is as effective in plaque removal and fluoride release as toothbrushing with fluoride toothpaste. This single-blind, randomized, crossover study was conducted at the Department of Cariology, University of Gothenburg, Gothenburg, Sweden, from February 2010 to January 2011. Fifteen healthy subjects participated in this study. The participants were instructed to use the following: (1) 0.5% NaF-impregnated miswak, (2) nonfluoridated miswak, (3) toothbrush with nonfluoride toothpaste, and (4) toothbrush with 1450 ppm fluoride toothpaste. Each method was used twice a day for 1 week after which plaque amount and fluoride concentration in resting saliva were measured. There was a 1-week washout period between each method. No significant difference between miswak and tooth-brushing was found regarding plaque removal on buccal and lingual surfaces. A somewhat higher fluoride concentration in resting saliva was found after using impregnated miswak when compared with toothbrushing with fluoride toothpaste (p toothbrushing showed the same plaque removing effect on buccal and lingual surfaces. Miswak impregnated with 0.5% NaF resulted in a higher concentration of fluoride in saliva than brushing with 1450 ppm fluoride toothpaste. Miswak impregnated with 0.5% NaF and toothbrushing results in comparable plaque removal and about the same fluoride concentration in saliva even it was somewhat higher for impregnated miswak.

  17. Method for routine determination of fluoride in urine by selective ion- electrode

    International Nuclear Information System (INIS)

    Pires, M.A.F.; Bellintani, S.A.

    1985-01-01

    A simple, fast and sensitive method is outlined for determining fluoride in urine of workers who handle fluoride compounds. The determination is based on the measurement of fluoride by ion selective electrode. Cationic interferents like Ca ++ , Mg ++ , Fe +++ and Al +++ are complexed by EDTA and citric acid. Common anions present in urine, such as Cl - , PO --- 4 and SO -- 4 do not interfere in the method. (Author) [pt

  18. Physiology and toxicity of fluoride

    Directory of Open Access Journals (Sweden)

    Dhar Vineet

    2009-01-01

    Full Text Available Fluoride has been described as an essential element needed for normal development and growth of animals and extremely useful for human beings. Fluoride is abundant in the environment and the main source of fluoride to humans is drinking water. It has been proved to be beneficial in recommended doses, and at the same time its toxicity at higher levels has also been well established. Fluoride gets accumulated in hard tissues of the body and has been know to play an important role in mineralization of bone and teeth. At high levels it has been known to cause dental and skeletal fluorosis. There are suggested effects of very high levels of fluoride on various body organs and genetic material. The purpose of this paper is to review the various aspects of fluoride and its importance in human life.

  19. Magnesium fluoride recovery method

    International Nuclear Information System (INIS)

    Gay, R.L.; McKenzie, D.E.

    1989-01-01

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag formed in the production of metallic uranium by the reduction of depleted uranium tetrafluoride with metallic magnesium in a retort wherein the slag contains the free metals magnesium and uranium and also oxides and fluorides of the metals. The slag having a radioactivity level of at least about 7,000 rhoCi/gm. The method comprises the steps of: grinding the slag to a median particle size of about 200 microns; contacting the ground slag in a reaction zone with an acid having a strength of from about 0.5 to 1.5 N for a time of from about 4 to about 20 hours in the presence of a catalytic amount of iron; removing the liquid product; treating the particulate solid product; repeating the last two steps at least one more time to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 rhoCi/gm

  20. On forms of U(4) existence in fluoride solutions

    International Nuclear Information System (INIS)

    Borin, L.L.; Koneva, L.G.

    1981-01-01

    The values of thermodynamic and concentration constants for I=0.12 are calculated on the basis of the values of the concentration constants of U(4) complexing with fluoride-ion, presented in literature, using the equations of Vasil'ev, Davies, Van Panthaleon- Van Eck. For the ionic force the ion compositions of U(4) solutions at different equilibrium concentrations of F - in the solution are calculated. Higher yields of the complexes with even number of fluorine ions and considerable role of the anionic fluoride complexes of U(4) are shown [ru

  1. Fluoride ion release and solubility of fluoride enriched interim cements.

    Science.gov (United States)

    Lewinstein, Israel; Block, Jonathan; Melamed, Guy; Dolev, Eran; Matalon, Shlomo; Ormianer, Zeev

    2014-08-01

    Interim and definitive restorations cemented with interim cements for a prolonged interval are susceptible to bacterial infiltration and caries formation. The purpose of this in vitro study was to evaluate the long-term fluoride release and solubility of aged ZnO-based interim cements enriched separately with 0.4% NaF and SnF2. Four different brands of cements (Tempbond, Tempbond NE, Procem, and Freegenol) were tested for fluoride release and solubility. For every test, 6 disk specimens of each cement with NaF and SnF2, and 6 with no fluoride enrichment (control) were fabricated, for a total of 72 specimens. The disks were incubated in deionized water. Fluoride ion release was recorded at 1, 7, 14, 21, 63, 91, and 182 days. Solubility was calculated as weight percent after 90 days of incubation. The data were analyzed by analysis of variance with repeated measures and the Tukey honestly significant difference post hoc test (Pfluorides released fluoride ions for at least 182 days. Cements mixed with NaF released more fluoride ions than those mixed with SnF2 (P.97), indicating a diffusion-controlled fluoride release. Cement and fluoride types were the main affecting factors in fluoride ion release. The addition of fluorides slightly increased the solubility of the cements. Given their long-term sustained and diffusive controlled release, these fluorides, particularly NaF when mixed with ZnO-based interim cements, may be useful for caries prevention under provisionally cemented restorations. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  2. Energy Transfer in Supramolecular Heteronuclear Lanthanide Dimers and Application to Fluoride Sensing in Water.

    Science.gov (United States)

    Nonat, Aline; Liu, Tao; Jeannin, Olivier; Camerel, Franck; Charbonnière, Loïc J

    2018-03-12

    In the presence of fluoride anions, [LnL(H 2 O)] + complexes, based on the coordination of a lanthanide (Ln) cation into the cavity of a C 2v symmetrical cyclen-based ligand (L), self-assemble in water to form [(LnL) 2 F] + dimers. The crystal structures of the Yb hydrated monomer and of the fluorinated dimer are reported and analyzed to unravel the impact of the cumulative effect of weak hydrogen bonding and aromatic stacking interactions in the supramolecular assembly. The assembly is stable over a broad range of pH 3-8. A combination of equimolar amounts of Eu and Tb complexes led to a quasistatistical mixture of homo- and heterodimers, as observed by using electrospray mass spectrometry. In the heterodimers, selective excitation into the 7 F 6 → 5 D 4 absorption band of the Tb center at λ=488 nm allowed the observation of a Tb-to-Eu downshifting energy transfer, not observed in the absence of fluoride ions. Analysis of the excited-state lifetimes of the dimers within the frame of the Förster theory of energy transfer showed the transfer to have an efficiency of 34 %, with a corresponding Förster radius of 4.1 Å; thereby, unraveling the short Ln-Ln distance as a crucial parameter of the energy-transfer process. By using equimolar mixtures of the Tb and Eu complexes, the energy-transfer phenomenon was used for a ratiometric sensing of fluoride anions in water with a detection limit of 17.7 nm. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Fluoride removal by Al, Ti, and Fe hydroxides and coexisting ion effect.

    Science.gov (United States)

    Zhang, Jianfeng; Brutus, Timothy E; Cheng, Jiemin; Meng, Xiaoguang

    2017-07-01

    Batch experiments were conducted to evaluate fluoride removal by Al, Fe, and Ti-based coagulants and adsorbents, as well as the effects of coexisting ions and formation of aluminum-fluoride complexes on fluoride removal by co-precipitation with alum (Al 2 (SO 4 ) 3 ·18H 2 O). Aluminum sulfate was more efficient than the other coagulants for fluoride removal in the pH range between 6 and 8. Nano-crystalline TiO 2 was more effective for fluoride removal than Al and Fe hydroxides in a pH range of 3-5. Coexisting anions in water decreased the removal of fluoride in the order: phosphate (2.5mg/L)>arsenate (0.1mg/L)>bicarbonate (200mg/L)>sulfate (100mg/L)=nitrate (100mg/L)>silicate (10mg/L) at a pH of 6.0. The effect of silicate became more significant at pH>7.0. Calcium and magnesium improved the removal of fluoride. Zeta-potential measurements determined that the adsorption of fluoride shifted the PZC of Al(OH) 3 precipitates from 8.9 to 8.4, indicating the chemical adsorption of fluoride at the surface. The presence of fluoride in solution significantly increased the soluble aluminum concentration at pHfluoride during co-precipitation with aluminum sulfate. Copyright © 2017. Published by Elsevier B.V.

  4. IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 3. Heavy Lanthanides (Gd–Lu)

    Energy Technology Data Exchange (ETDEWEB)

    Mioduski, Tomasz [Institute of Nuclear Chemistry and Technology, 03195 Warszawa (Poland); Gumiński, Cezary, E-mail: cegie@chem.uw.edu.pl [Department of Chemistry, University of Warsaw, 02093 Warszawa (Poland); Zeng, Dewen, E-mail: dewen-zeng@hotmail.com [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2015-06-15

    This is the third part of the volume devoted to solubility data for the rare earth metal (REM) fluorides in water and in aqueous ternary and multicomponent systems. It covers experimental results of trivalent fluorides of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu (so-called heavy lanthanides), since no quantitative data on solubilities of TbF{sub 4} and YbF{sub 2} (the most stable compounds at these valencies) are available. The related literature has been covered through the end of 2014. Compilations of all available papers with the solubility data are introduced for each REM fluoride with a corresponding critical evaluation. Every such assessment contains a collection of all solubility results in aqueous solution, a selection of suggested solubility data, a solubility equation, and a brief discussion of the multicomponent systems. Only simple fluorides (no complexes or double salts) are treated as the input substances in this report. General features of the systems, such as nature of the equilibrium solid phases, solubility as a function of temperature, influence of ionic strength, solution pH, mixed solvent medium on the solubility, quality of the solubility results, and the solubility as a function of REM atomic number, have already been presented in Part 1 of the volume.

  5. A calcite permeable reactive barrier for the remediation of Fluoride from spent potliner (SPL) contaminated groundwater

    DEFF Research Database (Denmark)

    Turner, B.D.; Binning, Philip John; Sloan, S.W.

    2008-01-01

    The use of calcite (CaCO3) as a substrate for a permeable reactive barrier (PRB) for removing fluoride from contaminated groundwater is proposed and is illustrated by application to groundwater contaminated by spent potliner leachate (SPL), a waste derived from the aluminium smelting process....... The paper focuses on two issues in the implementation of calcite permeable reactive barriers for remediating fluoride contaminated water: the impact of the groundwater chemical matrix and CO2 addition on fluoride removal. Column tests comparing pure NaF solutions, synthetic SPL solutions, and actual SPL...... leachate indicate that the complex chemical matrix of the SPL leachate can impact fluoride removal significantly. For SPL contaminant mixtures, fluoride removal is initially less than expected from idealized, pure, solutions. However, with time, the effect of other contaminants on fluoride removal...

  6. Acute multi-sgRNA knockdown of KEOPS complex genes reproduces the microcephaly phenotype of the stable knockout zebrafish model.

    Directory of Open Access Journals (Sweden)

    Tilman Jobst-Schwan

    Full Text Available Until recently, morpholino oligonucleotides have been widely employed in zebrafish as an acute and efficient loss-of-function assay. However, off-target effects and reproducibility issues when compared to stable knockout lines have compromised their further use. Here we employed an acute CRISPR/Cas approach using multiple single guide RNAs targeting simultaneously different positions in two exemplar genes (osgep or tprkb to increase the likelihood of generating mutations on both alleles in the injected F0 generation and to achieve a similar effect as morpholinos but with the reproducibility of stable lines. This multi single guide RNA approach resulted in median likelihoods for at least one mutation on each allele of >99% and sgRNA specific insertion/deletion profiles as revealed by deep-sequencing. Immunoblot showed a significant reduction for Osgep and Tprkb proteins. For both genes, the acute multi-sgRNA knockout recapitulated the microcephaly phenotype and reduction in survival that we observed previously in stable knockout lines, though milder in the acute multi-sgRNA knockout. Finally, we quantify the degree of mutagenesis by deep sequencing, and provide a mathematical model to quantitate the chance for a biallelic loss-of-function mutation. Our findings can be generalized to acute and stable CRISPR/Cas targeting for any zebrafish gene of interest.

  7. Acceptability of Salt Fluoridation in a Rural Latino Community in the United States: An Ethnographic Study.

    Directory of Open Access Journals (Sweden)

    Judith C Barker

    acceptable, the feasibility of producing and distributing fluoridated salt in the United States is, however, complex and challenging.

  8. Fluoride Content in Alcoholic Drinks.

    Science.gov (United States)

    Goschorska, Marta; Gutowska, Izabela; Baranowska-Bosiacka, Irena; Rać, Monika Ewa; Chlubek, Dariusz

    2016-06-01

    The aim of the study was to determine the role of alcoholic drinks as a potential source of dietary fluoride by means of measuring fluoride levels in selected alcoholic drinks available on the Polish market that are also diverse in terms of the percentage content of ethanol. The study was conducted on 48 types of drinks with low, medium, and high alcohol content available on the Polish market and offered by various manufacturers, both Polish and foreign. Fluoride concentrations in individual samples were measured by potentiometric method with a fluoride ion-selective electrode. The highest fluoride levels were determined in the lowest percentage drinks (less than 10 % v/v ethanol), with the lowest fluoride levels observed in the highest percentage drinks (above 40 % v/v ethanol). In terms of types of alcoholic drinks, the highest fluoride levels were determined in beers and wines, while the lowest levels were observed in vodkas. These data confirm the fact that alcoholic beverages need to be considered as a significant source of fluoride delivered into the body.

  9. FORMATION OF PHOSPHATE-CONTAINING CALCIUM-FLUORIDE AT THE EXPENSE OF ENAMEL, HYDROXYAPATITE AND FLUORAPATITE

    NARCIS (Netherlands)

    CHRISTOFFERSEN, J; CHRISTOFFERSEN, MR; ARENDS, J; LEONARDSEN, ES

    1995-01-01

    During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were

  10. Preparation of sodium fluoride agglomerates for selective adsorption of uranium hexafluoride (U F6)

    International Nuclear Information System (INIS)

    Castro, A.R.; Maximiano, C.; Shimba, R.; Silva, E.R.F.

    1995-01-01

    Uranium hexafluoride (U F 6 ) and Sodium Fluoride (NaF) reacts reversibly to form a solid complex. Such reversibility accounts for the great interest in using Sodium Fluoride (NaF) to separate Uranium Hexafluoride (U F 6 ) from other gases. Therefore a chemical trap offers an alternative to the cryogenic trapping device. (author). 3 refs, 1 fig, 4 tabs

  11. Method for fluoride routine determination in urine of personnel exposed, by ion selective electrode

    International Nuclear Information System (INIS)

    Pires, M.A.F.; Bellintani, S.A.

    1986-01-01

    A simple, fast and sensible method is outlined for the determination of fluoride in urine of workers that handle fluorine compounds. The determination is based on the measurement of fluoride by ion selective electrode. Cationic interference like Ca ++ , Mg ++ , Fe +++ and Al +++ are complexed by EDTA and citric acid. (Author) [pt

  12. Bioactivity and fluoride release of strontium and fluoride modified Biodentine.

    Science.gov (United States)

    Simila, Hazel O; Karpukhina, Natalia; Hill, Robert G

    2018-01-01

    Biodentine™ is a novel tricalcium silicate based material used both as a coronal dentine replacement and in pulp therapy. Its multiple use in sealing perforations, pulp capping and as a temporary restoration arises from its ability to promote dentine formation and to confer an excellent marginal seal. However, there is still room for improvement of this cement as it lacks the anticariogenic effect typically conferred by fluoride ion release as seen in glass ionomer cement based dental materials. Therefore, this study was conducted to investigate the impact of bioactive glass addition to Biodentine™. was to compare the apatite formation capacity, specificity of the apatite type formed and fluoride ion release by Biodentine™ cements that have been modified by three different compositions of bioactive glasses. High fluoride, high strontium and high fluoride plus strontium containing bioactive glasses were synthesized, incorporated into Biodentine™ powder and four types of cements prepared. These cements were immersed in phosphate buffered saline solution and incubated for a period of 3 and 24h, 3, 7 and 14 days. Fourier transform infra-red spectroscopy, X-ray diffraction, magic angle spinning nuclear magnetic resonance and fluoride ion release studies were performed. Bioactive glass addition to Biodentine™ led to pronounced formation of apatite. Where the bioactive glass contained fluoride, fluorapatite and fluoride ion release were demonstrated. Eliciting fluorapatite formation and fluoride ion release from Biodentine™ is an important development as fluoride is known to have antibacterial and anticariogenic effects. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Urinary Fluoride Concentration in Children with Disabilities Following Long-Term Fluoride Tablet Ingestion

    Science.gov (United States)

    Liu, Hsiu-Yueh; Chen, Jung-Ren; Hung, Hsin-Chia; Hsiao, Szu-Yu; Huang, Shun-Te; Chen, Hong-Sen

    2011-01-01

    Urine is the most commonly utilized biomarker for fluoride excretion in public health and epidemiological studies. Approximately 30-50% of fluoride is excreted from urine in children. Urinary fluoride excretion reflects the total fluoride intake from multiple sources. After administering fluoride tablets to children with disabilities, urinary…

  14. [Using barium fluoride fine particles as stationary phase for TLC/FTIR analysis].

    Science.gov (United States)

    Liu, Xi; Pan, Qing-hua; Ding, Jie; Zhu, Qing; He, An-qi; Yue, Shi-juan; Li, Xiao-pei; Hu, Li-ping; Xia, Jin-ming; Liu, Cui-ge; Wei, Yong-ju; Yu, Jiang; Yang, Zhan-lan; Zhu, Xi; Xu, Yi-zhuang; Wu, Jin-guang

    2011-07-01

    In situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures. However, the progress in this technique was quite slow. The reason is that conventional stationary phase such as silica gel etc. has strong absorption in FTIR spectrum and thus brings about severe interference in the detection of samples. To solve the problem, the authors propose to use barium fluoride fine particles as stationary phase of TLC plate. The reasons are as follows: Barium fluoride wafer has been extensively used as infrared window in FTIR experiments and it has no absorbance in an IR region between 4 000 and 800 cm'. As a matter of fact, the atomic mass of barium and fluoride is quite large, thus the normal vibration of BaF2 lattice is limited in far-IR region and low frequency part of mid-IR region. Therefore, the interference caused by IR absorption of stationary phase can be resolved if BaF2 is used as stationary phase of TLC plate. Moreover, BaF2 is quite stable and insolvable in water and most organic solvents and it will not be dissolved by mobile phase or react with samples in TLC separation. Additionally, decreasing the particle size of BaF2 is very important in TLC/FTIR analysis technique. The reason is two-fold: First, decreasing the particle size of stationary phase is helpful to improving the efficiency of separation by TLC plate; second, decreasing the size of BaFz particle can improve the quality of FTIR spectra by alleviating the problem of light scattering. By optimizing the synthetic conditions, fine particles of barium fluoride were obtained. SEM results indicate that the size of the BaF2 particles is around 500 nm. FTIR spectrum of the BaF2 particles shows that no absorption of impurity was observed. Moreover, the elevation of baseline caused by light scattering is insignificant. The authors have developed a new technique named "settlement volatilization method" to prepare TLC plate without polymeric adhesive that may bring about significant

  15. 49 CFR 173.163 - Hydrogen fluoride.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned in...

  16. Growth of fluoride treated Kalanchoe pinnata plants

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, H.N.; Applegate, H.G.

    1962-01-01

    Kalanchoe pinnata plants can absorb fluoride through roots. The absorption is related to the amount of fluoride applied to the soil. There appeared to be a relationship between the amount of fluoride adsorbed and the subsequent growth of the plants. Plants which adsorbed the largest amounts of fluoride had the greatest increase in growth.

  17. A thermally stable and sterically unprotected terminal electrophilic phosphinidene complex of cobalt and its conversion to an eta(1)-phosphirene.

    Science.gov (United States)

    Sánchez-Nieves, Javier; Sterenberg, Brian T; Udachin, Konstantin A; Carty, Arthur J

    2003-03-05

    The terminal chloroaminophosphido complex [Co(CO)3(PPh3){P(Cl)NiPr2}] is formed via reaction of K[Co(CO)4] with iPr2NPCl2 in the presence of triphenylphosphine. Chloride abstraction by aluminum trichloride leads to the first terminal phosphinidene complex of cobalt, [Co(CO)3(PPh3)(PNiPr2)][AlCl4]. The electrophilicity of the phosphinidene was demonstrated by its reaction with diphenylacetylene to form the phosphirene complex [Co(CO)3(PPh3){P(NiPr2)C(Ph)C(Ph)}][AlCl4].

  18. Effect of silver diamine fluoride (SDF) on the dentin-pulp complex: ex vivo histological analysis on human primary teeth and rat molars.

    Science.gov (United States)

    Rossi, Glenda; Squassi, Aldo; Mandalunis, Patricia; Kaplan, Andrea

    2017-04-01

    The aim of this study was to determine the effect of SDF on the dentin-pulp complex using two models: teeth after SDF application (ex vivo) and experimental animal molars. A descriptive study was performed using two models. In the first model, primary teeth (ex vivo) with enamel-dentin caries, without pulp involvement and previously treated with 38% SDF, were evaluated by means of two techniques: (a) Scanning Electron Microscopy (SEM) and energy-dispersive X-ray detector (EDS) to determine qualitative and quantitative composition, and (b) brightfield optical microscopy (OM) after decalcification. The second model used laboratory animal molars from 12 male Wistar rats. Standardized enamel-dentin cavities approximately 0.5 mm deep were made the distal fossa of the occlusal face of both first lower molars, to one of which a 38% SDF solution was applied, while the other was used as a control. Histological sections were prepared and dental pulp was evaluated qualitatively in both groups. SEM on ex vivo teeth showed areas of hypermineralization in the intertubular dentin and few blocked tubules, while EDS detected Ag in the center of the lesion (7.34%), its concentration declining at the edges (1.71%), with none in the areas farthest from the lesion. OM showed SDF sealing the tubules only at the site where it had been placed, with limited penetration beneath, the tubules appeared normal and the pulp tissue associated to treated caries showed chronic inflammatory infiltrate and formation of tertiary dentin, with no Ag precipitate. In the experimental animal model, pulp histology was not significantly altered in the molar cavities exposed to SDF. The observations using the different techniques on dental tissues suggest that SDF causes minimal adverse effects. The results of this study may contribute to further studies on the suitability of SDF as a cost-effective strategy for treating caries. Sociedad Argentina de Investigación Odontológica.

  19. Highly Chemo- and Stereoselective Transfer Semihydrogenation of Alkynes Catalyzed by a Stable, Well-defined Manganese(II) Complex

    KAUST Repository

    Brzozowska, Aleksandra

    2018-03-30

    The first example of manganese catalyzed semihydrogenation of internal alkynes to (Z)-alkenes using ammonia borane as a hydrogen donor is reported. The reaction is catalyzed by a pincer complex of the earth abundant manganese(II) salt in the absence of any additives, base or super hydride. The ammonia borane smoothly reduces the manganese pre-catalyst [Mn(II)-PNP][Cl]2 to the catalytically active species [Mn(I)-PNP]-hydride in the triplet spin state. This manganese hydride is highly stabilized by complexation with the alkyne substrate. Computational DFT analysis studies of the reaction mechanism rationalizes the origin of stereoselectivity towards formation of (Z)-alkenes.

  20. Matrix supported tailored polymer for solid phase extraction of fluoride from variety of aqueous streams

    International Nuclear Information System (INIS)

    Thakur, Neha; Kumar, Sanjukta A.; Wagh, D.N.; Das, Sadananda; Pandey, Ashok K.; Kumar, Sangita D.; Reddy, A.V.R.

    2012-01-01

    Highlights: ► Th complexed with poly (bis[2-(methacryloyloxy)-ethyl]phosphate) as tailored polymer membranes. ► Membranes offered high capacity and selectivity for fluoride in aqueous media. ► Quantitative uptake (80 ± 5%) of fluoride. ► Fast sorption kinetics. ► Reusability of polymer membranes. - Abstract: Fluoride related health hazards (fluorosis) are a major environmental problem in many regions of the world. It affects teeth; skeleton and its accumulation over a long period can lead to changes in the DNA structure. It is thus absolutely essential to bring down the fluoride levels to acceptable limits. Here, we present a new inorganic–organic hybrid polymer sorbent having tailored fixed-sites for fluoride sorption. The matrix supported poly (bis[2-(methacryloyloxy)-ethyl]phosphate) was prepared by photo-initiator induced graft-polymerization in fibrous and microporous (sheet) host poly(propylene) substrates. These substrates were conditioned for selective fluoride sorption by forming thorium complex with phosphate groups on bis[2-methacryloyloxy)-ethyl] phosphate (MEP). These tailored sorbents were studied for their selectivity towards fluoride in aqueous media having different chemical conditions. The fibrous sorbent was found to take up fluoride with a faster rate (15 min for ≈76% sorption) than the sheet sorbent. But, the fluoride loading capacity of sheet sorbent (4320 mg kg −1 ), was higher than fibrous and any other sorbent reported in the literature so far. The sorbent developed in the present work was found to be reusable after desorption of fluoride using NaOH solution. It was tested for solid phase extraction of fluoride from natural water samples.

  1. Physical properties of thorium fluoride

    International Nuclear Information System (INIS)

    Van Uitert, L.G.; Guggenheim, H.J.; O'Bryan, H.M.; Warner, A.W. Jr.; Brownlow, D.; Bernstein, J.L.; Pasteur, G.A.; Johnson, L.F.

    1976-01-01

    Thorium fluoride has many properties that make it of interest for infrared windows. It is transparent to about eleven microns, is unaffected by moisture, has a moderate hardness, and suffers little dimensional change upon heating

  2. Optical Properties of Chemical Bath Deposited Bismuth Fluoride (Bif ...

    African Journals Online (AJOL)

    Thin films of bismuth fluoride (Bif3) were deposited using chemical bath deposition technique from chemical baths containing solutions of bismuth nitrate (EDTA) and potassium bromide with EDTA as complexing agent in slightly acidic medium. The films were characterized using Fourier transform infrared (FTIR) ...

  3. Optical detection of sodium salts of fluoride, acetate and phosphate

    Indian Academy of Sciences (India)

    Optical detection of sodium salts of fluoride, acetate and phosphate by a diacylhydrazine ligand by the formation of a colour alkali metal complex. Purnandhu Bose Ranjan Dutta I ... Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A and 2B Raja S C Mullick Road, Kolkata 700032, India ...

  4. Optical detection of sodium salts of fluoride, acetate and phosphate ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 6. Optical detection of sodium salts of fluoride, acetate and phosphate by a diacylhydrazine ligand by the formation of a colour alkali metal complex. Purnandhu Bose Ranjan Dutta I Ravikumar Pradyut Ghosh. Volume 123 Issue 6 November 2011 pp 869- ...

  5. Optical Detection of Sodium Salts of Fluoride, Acetate and ...

    Indian Academy of Sciences (India)

    Administrator

    Optical Detection of Sodium Salts of Fluoride, Acetate and Phosphate by a Diacylhydrazine. Ligand via the Formation of a Colour Alkali Metal Complex. Purnandhu Bose, Ranjan Dutta, I. Ravikumar and Pradyut Ghosh. ∗. Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A & 2B Raja ...

  6. An Overview of Liquid Fluoride Salt Heat Transport Systems

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, David Eugene [ORNL; Cetiner, Sacit M [ORNL

    2010-09-01

    , and this report also describes more recently developed technologies such as dry gas seals. This report also provides a high-level, parametric evaluation of LSHT loop performance to allow general intercomparisons between heat-transport fluid options as well as provide an overview of the properties and requirements for a representative loop. A compilation of relevant thermophysical properties of useful fluoride salts is also included for salt heat transport systems. Fluoride salts can be highly corrosive depending on the container materials selected, the salt chemistry, and the operating procedures used. The report includes an overview of the state-of-the-art in reduction-oxidation chemistry control methodologies employed to minimize corrosion issues. Salt chemistry control technology, however, remains at too low a level of understanding for widespread industrial usage. Loop operational issues such as start-up procedures and system freeze-up vulnerability are also discussed. Liquid fluoride salts are a leading candidate heat transport medium for high-temperature applications. This report provides an overview of the current status of liquid salt heat transport technology. The report includes a high-level, parametric evaluation of liquid fluoride salt heat transport loop performance to allow intercomparisons between heat-transport fluid options as well as providing an overview of the properties and requirements for a representative loop. Much of the information presented here derives from the earlier molten salt reactor program and a significant advantage of fluoride salts, as high temperature heat transport media is their consequent relative technological maturity. The report also includes a compilation of relevant thermophysical properties of useful heat transport fluoride salts. Fluoride salts are both thermally stable and with proper chemistry control can be relatively chemically inert. Fluoride salts can, however, be highly corrosive depending on the container

  7. Increasing volume and complexity of pediatric epilepsy surgery with stable seizure outcome between 2008 and 2014: A nationwide multicenter study.

    Science.gov (United States)

    Barba, Carmen; Specchio, Nicola; Guerrini, Renzo; Tassi, Laura; De Masi, Salvatore; Cardinale, Francesco; Pellacani, Simona; De Palma, Luca; Battaglia, Domenica; Tamburrini, Gianpiero; Didato, Giuseppe; Freri, Elena; Consales, Alessandro; Nozza, Paolo; Zamponi, Nelia; Cesaroni, Elisabetta; Di Gennaro, Giancarlo; Esposito, Vincenzo; Giulioni, Marco; Tinuper, Paolo; Colicchio, Gabriella; Rocchi, Raffaele; Rubboli, Guido; Giordano, Flavio; Lo Russo, Giorgio; Marras, Carlo Efisio; Cossu, Massimo

    2017-10-01

    The objective of the study was to assess common practice in pediatric epilepsy surgery in Italy between 2008 and 2014. A survey was conducted among nine Italian epilepsy surgery centers to collect information on presurgical and postsurgical evaluation protocols, volumes and types of surgical interventions, and etiologies and seizure outcomes in pediatric epilepsy surgery between 2008 and 2014. Retrospective data on 527 surgical procedures were collected. The most frequent surgical approaches were temporal lobe resections and disconnections (133, 25.2%) and extratemporal lesionectomies (128, 24.3%); the most frequent etiologies were FCD II (107, 20.3%) and glioneuronal tumors (105, 19.9%). Volumes of surgeries increased over time independently from the age at surgery and the epilepsy surgery center. Engel class I was achieved in 73.6% of patients (range: 54.8 to 91.7%), with no significant changes between 2008 and 2014. Univariate analyses showed a decrease in the proportion of temporal resections and tumors and an increase in the proportion of FCDII, while multivariate analyses revealed an increase in the proportion of extratemporal surgeries over time. A higher proportion of temporal surgeries and tumors and a lower proportion of extratemporal and multilobar surgeries and of FCD were observed in low (epilepsy surgery in Italy between 2008 and 2014, associated with a stable seizure outcome. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Chronic Fluoride Toxicity: Dental Fluorosis

    Science.gov (United States)

    DenBesten, Pamela; Li, Wu

    2012-01-01

    Dental fluorosis occurs as a result of excess fluoride ingestion during tooth formation. Enamel fluorosis and primary dentin fluorosis can only occur when teeth are forming, and therefore fluoride exposure (as it relates to dental fluorosis) occurs during childhood. In the permanent dentition, this would begin with the lower incisors, which complete mineralization at approximately 2–3 years of age, and end after mineralization of the third molars. The white opaque appearance of fluorosed enamel is caused by a hypomineralized enamel subsurface; with more severe dental fluorosis, pitting and a loss of the enamel surface occurs, leading to secondary staining (appearing as a brown color). Many of the changes caused by fluoride are related to cell/matrix/mineral interactions as the teeth are forming. At the early maturation stage, the relative quantity of amelogenin protein is increased in fluorosed enamel in a dose-related manner. This appears to result from a delay in the removal of amelogenins as the enamel matures. In vitro, when fluoride is incorporated into the mineral, more protein binds to the forming mineral, and protein removal by proteinases is delayed. This suggests that altered protein/mineral interactions are in part responsible for retention of amelogenins and the resultant hypomineralization that occurs in fluorosed enamel. Fluoride also appears to enhance mineral precipitation in forming teeth, resulting in hypermineralized bands of enamel, which are then followed by hypomineralized bands. Enhanced mineral precipitation with local increases in matrix acidity may affect maturation stage ameloblast modulation, potentially explaining the doserelated decrease in cycles of ameloblast modulation from ruffleended to smooth-ended cells that occur with fluoride exposure in rodents. Specific cellular effects of fluoride have been implicated, but more research is needed to determine which of these changes are relevant to the formation of fluorosed teeth. As

  9. Metal Fluorides, Metal Chlorides and Halogenated Metal Oxides as Lewis Acidic Heterogeneous Catalysts. Providing Some Context for Nanostructured Metal Fluorides.

    Science.gov (United States)

    Lennon, David; Winfield, John M

    2017-01-28

    Aspects of the chemistry of selected metal fluorides, which are pertinent to their real or potential use as Lewis acidic, heterogeneous catalysts, are reviewed. Particular attention is paid to β-aluminum trifluoride, aluminum chlorofluoride and aluminas γ and η, whose surfaces become partially fluorinated or chlorinated, through pre-treatment with halogenating reagents or during a catalytic reaction. In these cases, direct comparisons with nanostructured metal fluorides are possible. In the second part of the review, attention is directed to iron(III) and copper(II) metal chlorides, whose Lewis acidity and potential redox function have had important catalytic implications in large-scale chlorohydrocarbons chemistry. Recent work, which highlights the complexity of reactions that can occur in the presence of supported copper(II) chloride as an oxychlorination catalyst, is featured. Although direct comparisons with nanostructured fluorides are not currently possible, the work could be relevant to possible future catalytic developments in nanostructured materials.

  10. Fluoride bioavailability in saliva and plaque

    Science.gov (United States)

    2012-01-01

    Background Different fluoride formulations may have different effects on caries prevention. It was the aim of this clinical study to assess the fluoride content, provided by NaF compared to amine fluoride, in saliva and plaque. Methods Eight trained volunteers brushed their teeth in the morning for 3 minutes with either NaF or amine fluoride, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva and plaque was measured, and the fluoride content was analysed using a fluoride sensitive electrode. All subjects repeated all study cycles 5 times, and 3 cycles per subject underwent statistical analysis using the Wilcoxon-Mann-Whitney test. Results Immediately after brushing the fluoride concentration in saliva increased rapidly and dropped to the baseline level after 360 minutes. No difference was found between NaF and amine fluoride. All plaque fluoride levels were elevated after 30 minutes until 120 minutes after tooth brushing, and decreasing after 360 minutes to baseline. According to the highly individual profile of fluoride in saliva and plaque, both levels of bioavailability correlated for the first 30 minutes, and the fluoride content of saliva and plaque was back to baseline after 6 hours. Conclusions Fluoride levels in saliva and plaque are interindividually highly variable. However, no significant difference in bioavailability between NaF and amine fluoride, in saliva, or in plaque was found. PMID:22230722

  11. Expanding the Therapeutic Potential of the Iron Chelator Deferasirox in the Development of Aqueous Stable Ti(IV) Anticancer Complexes.

    Science.gov (United States)

    Loza-Rosas, Sergio A; Vázquez-Salgado, Alexandra M; Rivero, Kennett I; Negrón, Lenny J; Delgado, Yamixa; Benjamín-Rivera, Josué A; Vázquez-Maldonado, Angel L; Parks, Timothy B; Munet-Colón, Charlene; Tinoco, Arthur D

    2017-07-17

    The recent X-ray structure of titanium(IV)-bound human serum transferrin (STf) exhibiting citrate as a synergistic anion reveals a difference in Ti(IV) coordination versus iron(III), the metal endogenously delivered by the protein to cells. This finding enriches our bioinspired drug design strategy for Ti(IV)-based anticancer therapeutics, which applies a family of Fe(III) chelators termed chemical transferrin mimetic (cTfm) ligands to inhibit Fe bioavailability in cancer cells. Deferasirox, a drug used for iron overload disease, is a cTfm ligand that models STf coordination to Fe(III), favoring Fe(III) binding versus Ti(IV). This metal affinity preference drives deferasirox to facilitate the release of cytotoxic Ti(IV) intracellularly in exchange for Fe(III). An aqueous speciation study performed by potentiometric titration from pH 4 to 8 with micromolar levels of Ti(IV) deferasirox at a 1:2 ratio reveals exclusively Ti(deferasirox) 2 in solution. The predominant complex at pH 7.4, [Ti(deferasirox) 2 ] 2- , exhibits the one of the highest aqueous stabilities observed for a potent cytotoxic Ti(IV) species, demonstrating little dissociation even after 1 month in cell culture media. UV-vis and 1 H NMR studies show that the stability is unaffected by the presence of biomolecular Ti(IV) binders such as citrate, STf, and albumin, which have been shown to induce dissociation or regulate cellular uptake and can alter the activity of other antiproliferative Ti(IV) complexes. Kinetic studies on [Ti(deferasirox) 2 ] 2- transmetalation with Fe(III) show that a labile Fe(III) source is required to induce this process. The initial step of this process occurs on the time scale of minutes, and equilibrium for the complete transmetalation is reached on a time scale of hours to a day. This work reveals a mechanism to deliver Ti(IV) compounds into cells and trigger Ti(IV) release by a labile Fe(III) species. Cellular studies including other cTfm ligands confirm the Fe(III) depletion

  12. Fluoride level in saliva after bonding orthodontic brackets with a fluoride containing adhesive

    NARCIS (Netherlands)

    Ogaard, B; Arends, J; Helseth, H; Dijkman, G; vanderKuijl, M

    The fluoride level in saliva is considered an important parameter in caries prevention. Elevation of the salivary fluoride level by a fluoride-releasing orthodontic bonding adhesive would most likely be beneficial in the prevention of enamel caries. In this study, the fluoride level in saliva was

  13. Urinary fluoride excretion in preschool children after intake of fluoridated milk and use of fluoride-containing toothpaste

    DEFF Research Database (Denmark)

    Norman, M; Twetman, S; Hultgren Talvilahti, A

    2017-01-01

    Objective: To assess the urinary fluoride excretion in preschool children after drinking fluoridated milk with 0.185 mg F and 0.375 mg F and to study the impact of use of fluoride toothpaste. Basic research design: Double-blind cross-over study. Participants: Nine healthy children, 2.5-4.5 years...

  14. Water Fluoridation Reporting System (Public Water Systems)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Water Fluoridation Reporting System (WFRS) has been developed to provide tools to assist states in managing fluoridation programs. WFRS is designed to track all...

  15. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    OpenAIRE

    Dugheri, Stefano; Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Mucci, Nicola; Arcangeli, Giulio

    2016-01-01

    Hydrogen fluoride (HF) is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13?mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impre...

  16. Structural stability, acidity, and halide selectivity of the fluoride riboswitch recognition site

    KAUST Repository

    Chawla, Mohit

    2015-01-14

    Using static and dynamics DFT methods we show that the Mg2+/F-/phosphate/water cluster at the center of the fluoride riboswitch is stable by its own and, once assembled, does not rely on any additional factor from the overall RNA fold. Further, we predict that the pKa of the water molecule bridging two Mg cations is around 8.4. We also demonstrate that the halide selectivity of the fluoride riboswitch is determined by the stronger Mg-F bond, which is capable of keeping together the cluster. Replacing F- with Cl- results in a cluster that is unstable under dynamic conditions. Similar conclusions on the structure and energetics of the cluster in the binding pocket of fluoride-inhibited pyrophosphatase suggest that the peculiarity of fluoride is in its ability to establish much stronger metal-halide bonds.

  17. Association of lifetime exposure to fluoride and cognitive functions in Chinese children

    DEFF Research Database (Denmark)

    Choi, Anna L; Zhang, Ying; Sun, Guifan

    2015-01-01

    BACKGROUND: A systematic review and meta-analysis of published studies on developmental fluoride neurotoxicity support the hypothesis that exposure to elevated concentrations of fluoride in water is neurotoxic during development. METHODS: We carried out a pilot study of 51 first-grade children...... functional domains: the Wide Range Assessment of Memory and Learning (WRAML), Wechsler Intelligence Scale for Children-Revised (WISC-IV) digit span and block design; finger tapping and grooved pegboard. Confounder-adjusted associations between exposure indicators and test scores were assessed using multiple...... of -4.28 (95% CI -8.22, -0.33) and backward score with -2.13 (95% CI -4.24, -0.02). CONCLUSIONS: This pilot study in a community with stable lifetime fluoride exposures supports the notion that fluoride in drinking water may produce developmental neurotoxicity, and that the dose-dependence underlying...

  18. Dynamic reorganization of chromatin structure and selective DNA demethylation prior to stable enhancer complex formation during differentiation of primary hematopoietic cells in vitro.

    Science.gov (United States)

    Tagoh, Hiromi; Melnik, Svitlana; Lefevre, Pascal; Chong, Suyinn; Riggs, Arthur D; Bonifer, Constanze

    2004-04-15

    In order to gain insights in the true molecular mechanisms involved in cell fate decisions, it is important to study the molecular details of gene activation where such decisions occur, which is at the level of the chromatin structure of individual genes. In the study presented here we addressed this issue and examined the dynamic development of an active chromatin structure at the chicken lysozyme locus during the differentiation of primary myeloid cells from transgenic mouse bone marrow. Using in vivo footprinting we found that stable enhancer complex assembly and high-level gene expression are late events in cell differentiation. However, even before the onset of gene expression and stable transcription factor binding, specific chromatin alterations are observed. This includes changes in DNA topology and the selective demethylation of CpG dinucleotides located in the cores of critical transcription factor binding sites, but not in flanking DNA. These results firmly support the idea that epigenetic programs guiding blood cell differentiation are engraved into the chromatin of lineage-specific genes and that such chromatin changes are implemented before cell lineage specification.

  19. Effects of fluorides on plants

    Energy Technology Data Exchange (ETDEWEB)

    Yamazoe, F.

    1975-11-01

    Fluorine compounds known to be air pollutants, such as hydrogen fluoride and silicon tetrachloride, are highly poisonous to plants even at ppm - ppb levels. As solid microparticles, acidic sodium fluoride and cryolite cause problems by adhering to plant leaves and absorbing into plant bodies. Plants are classified by their susceptibility to hydrogen fluoride: gladiolus, apricot, buckwheat, turnip and Vaccinium vitis-idaea are most susceptible showing slight injury at less than 5 ppb for 7-9 days; maize, pepper, and dahlia are fairly susceptible, followed by azalea, rose, lilac, and alfalfa, then by oak and tomato. Gladiolus is used as an indicator plant. The exposure factor for one species was known. The symptoms of plants exposed to gaseous fluorine compounds are described in detail at various concentrations. The causal mechanism of the injuries due to fluorine compounds is described in detail, with the method of determining the fluorine content of plant parts. 7 references.

  20. Anhydrous hydrogen fluoride electrolyte battery. [Patent application

    Science.gov (United States)

    Not Available

    1972-06-26

    It is an object of the invention to provide a primary cell or battery using ammonium fluoride--anhydrous hydrogen fluoride electrolyte having improved current and power production capabilities at low temperatures. It is operable at temperatures substantially above the boiling point of hydrogen fluoride. (GRA)

  1. Mechanism of HIV reverse transcriptase inhibition by zinc: formation of a highly stable enzyme-(primer-template) complex with profoundly diminished catalytic activity.

    Science.gov (United States)

    Fenstermacher, Katherine J; DeStefano, Jeffrey J

    2011-11-25

    Several physiologically relevant cations including Ca(2+), Mn(2+), and Zn(2+) have been shown to inhibit HIV reverse transcriptase (RT), presumably by competitively displacing one or more Mg(2+) ions bound to RT. We analyzed the effects of Zn(2+) on reverse transcription and compared them to Ca(2+) and Mn(2+). Using nucleotide extension efficiency as a readout, Zn(2+) showed significant inhibition of reactions with 2 mM Mg(2+), even when present at only ∼5 μM. Mn(2+) and Ca(2+) were also inhibitory but at higher concentrations. Both Mn(2+) and Zn(2+) (but not Ca(2+)) supported RT incorporation in the absence of Mg(2+) with Mn(2+) being much more efficient. The maximum extension rates with Zn(2+), Mn(2+), and Mg(2+) were ∼0.1, 1, and 3.5 nucleotides per second, respectively. Zinc supported optimal RNase H activity at ∼25 μM, similar to the optimal for nucleotide addition in the presence of low dNTP concentrations. Surprisingly, processivity (average number of nucleotides incorporated in a single binding event with enzyme) during reverse transcription was comparable with Zn(2+) and Mg(2+), and single RT molecules were able to continue extension in the presence of Zn(2+) for several hours on the same template. Consistent with this result, the half-life for RT-Zn(2+)-(primer-template) complexes was 220 ± 60 min and only 1.7 ± 1 min with Mg(2+), indicating ∼130-fold more stable binding with Zn(2+). Essentially, the presence of Zn(2+) promotes the formation of a highly stable slowly progressing RT-(primer-template) complex.

  2. Fluoride Iontophoresis Versus Topical Fluoride Application In The ...

    African Journals Online (AJOL)

    Material and Methods: Test teeth received a 2% neutral solution of sodium fluoride using Desensitron II Iontophoresis device with current and the control teeth received the solution on the device without current. Thirteen patients comprising eight females and five males who complained of tooth hypersensitivity participated in ...

  3. Colorimetric determination of the fluoride ion - application to uranium metal and to uranous fluoride

    International Nuclear Information System (INIS)

    Hering, H.; Hure, J.; Legrand, S.

    1949-12-01

    In the determination described for fluoride in U metal, the U is brought into H 2 SO 4 solution by anodic oxidation, the fluo-silicic acid is distilled by entrainment in water vapor, and the F ion is determined in the distillate by using the fact that it complexes Zr and thus prevents the formation of the Zr-alizarin S lake. For F ion in UF 4 , the compound is dissolved in a Na 2 CO 3 -H 2 O 2 mixture, and F is determined in the solution by the colorimetric method described. (author)

  4. Synthesis and X-ray Crystal Structure of a Stable cis-1,2-bis(diphenylphosphinoethene Monodentate Thiolate Platinum Complex and TGA Studies of its Precursors

    Directory of Open Access Journals (Sweden)

    Vaz Rodrigo H.

    2002-01-01

    Full Text Available The stable Pt(II complex [Pt(SPh2(dppen (4, (dppen, Ph2PCH=CHPPh2 was obtained from [PtCl(SPh2(SnPh3cod] (1 (cod = 1,5-cyclooctadiene by reductive elimination reaction of SnClPh3 and substitution of the cod ligand by the diphosphine, albeit in low yields. Yields of 80% were obtained when [Pt(SPh2cod] (3 was used as the starting material instead. The viability of these reactions was suggested by a TG study, performed on the starting materials. Complex 4 was characterized by multinuclear NMR (195Pt, 31P, ¹H and 13C and IR spectroscopies and elemental analysis. The molecular structure, solved by an X-ray diffraction study, exhibted a slightly distorted square-planar geometry and short C=C and Pt-P bond distances which were interpreted in terms of a p interaction between the double bond and the metal-ligand bond, as observed for other diphosphine compounds described previously.

  5. Water-soluble and photo-stable silver(I) dicarboxylate complexes containing 1,10-phenanthroline ligands: Antimicrobial and anticancer chemotherapeutic potential, DNA interactions and antioxidant activity.

    Science.gov (United States)

    Thornton, Laura; Dixit, Vidya; Assad, Letícia O N; Ribeiro, Thales P; Queiroz, Daniela D; Kellett, Andrew; Casey, Alan; Colleran, John; Pereira, Marcos D; Rochford, Garret; McCann, Malachy; O'Shea, Denis; Dempsey, Rita; McClean, Siobhán; Kia, Agnieszka Foltyn-Arfa; Walsh, Maureen; Creaven, Bernadette; Howe, Orla; Devereux, Michael

    2016-06-01

    The complexes [Ag2(OOC-(CH2)n-COO)] (n=1-10) (1-10) were synthesised and reacted with 1,10-phenanthroline (phen) to yield derivatives formulating as [Ag2(phen)x(OOC-(CH2)y-COO)]·zH2O (x=2 or 3; y=1-10; z=1-4) (11-20) which are highly water-soluble and photo-stable in aqueous solution. The phen derivatives 11-20 exhibit chemotherapeutic potential against Candida albicans, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and against cisplatin-sensitive breast (MCF-7) and resistant ovarian (SKOV-3) cancer cell lines. Cyclic voltammetric analysis and DNA binding and intercalation studies indicate that the mechanism of action of 11-20 is significantly different to that of their silver(I) dicarboxylate precursors and they do not induce DNA damage or ROS generation in mammalian cells. The representative complexes 9 and 19 (containing the undecanedioate ligand) were both found to significantly reduce superoxide and hydrogen peroxide induced oxidative stress in the yeast S. cerevisiae. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Interaction between Nbp35 and Cfd1 proteins of cytosolic Fe-S cluster assembly reveals a stable complex formation in Entamoeba histolytica.

    Directory of Open Access Journals (Sweden)

    Shadab Anwar

    Full Text Available Iron-Sulfur (Fe-S proteins are involved in many biological functions such as electron transport, photosynthesis, regulation of gene expression and enzymatic activities. Biosynthesis and transfer of Fe-S clusters depend on Fe-S clusters assembly processes such as ISC, SUF, NIF, and CIA systems. Unlike other eukaryotes which possess ISC and CIA systems, amitochondriate Entamoeba histolytica has retained NIF & CIA systems for Fe-S cluster assembly in the cytosol. In the present study, we have elucidated interaction between two proteins of E. histolytica CIA system, Cytosolic Fe-S cluster deficient 1 (Cfd1 protein and Nucleotide binding protein 35 (Nbp35. In-silico analysis showed that structural regions ranging from amino acid residues (P33-K35, G131-V135 and I147-E151 of Nbp35 and (G5-V6, M34-D39 and G46-A52 of Cfd1 are involved in the formation of protein-protein complex. Furthermore, Molecular dynamic (MD simulations study suggested that hydrophobic forces surpass over hydrophilic forces between Nbp35 and Cfd1 and Van-der-Waal interaction plays crucial role in the formation of stable complex. Both proteins were separately cloned, expressed as recombinant fusion proteins in E. coli and purified to homogeneity by affinity column chromatography. Physical interaction between Nbp35 and Cfd1 proteins was confirmed in vitro by co-purification of recombinant Nbp35 with thrombin digested Cfd1 and in vivo by pull down assay and immunoprecipitation. The insilico, in vitro as well as in vivo results prove a stable interaction between these two proteins, supporting the possibility of its involvement in Fe-S cluster transfer to target apo-proteins through CIA machinery in E. histolytica. Our study indicates that initial synthesis of a Fe-S precursor in mitochondria is not necessary for the formation of Cfd1-Nbp35 complex. Thus, Cfd1 and Nbp35 with the help of cytosolic NifS and NifU proteins can participate in the maturation of non-mitosomal Fe-S proteins

  7. Fluoride and Water (For Parents)

    Science.gov (United States)

    ... a safe and cost-effective way to reduce dental caries. Today, water fluoridation is estimated to reduce tooth ... rinses. But older kids at high risk for tooth decay may benefit from them. ... history of dental disease, recent periodontal surgery or disease, or a ...

  8. Special Report: Fluoridation of Water.

    Science.gov (United States)

    Hileman, Bette

    1988-01-01

    Reviews the controversy regarding water fluoridation in the United States during the last 50 years. Discusses the current status; benefits; and health risks including skeletal fluorosis, kidney disease, hypersensitivity, mutagenic effects, birth defects, and cancer. Presents statistics and anecdotal accounts. (CW)

  9. The role of fluoride in erosion therapy.

    Science.gov (United States)

    Huysmans, Marie-Charlotte; Young, Alix; Ganss, Carolina

    2014-01-01

    The role of fluoride in erosion therapy has long been questioned. However, recent research has yielded positive results. In this chapter, an overview of the literature is provided regarding the application of fluorides in the prevention and treatment of erosion and erosive wear. The results are presented and discussed for different fluoride sources such as monovalent and polyvalent fluorides, and for different vehicles such as toothpastes, solutions and rinses, as well as varnishes and gels. It is concluded that fluoride applications are very likely to be of use in the preventive treatment of erosive wear. Most promising are high-concentration, acidic formulations and the polyvalent fluoride sources, with the best evidence available for stannous fluoride. However, the evidence base for clinical effectiveness is still small. © 2014 S. Karger AG, Basel.

  10. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  11. Alimentary fluoride intake in preschool children

    Science.gov (United States)

    2011-01-01

    Background The knowledge of background alimentary fluoride intake in preschool children is of utmost importance for introducing optimal and safe caries preventive measures for both individuals and communities. The aim of this study was to assess the daily fluoride intake analyzing duplicate samples of food and beverages. An attempt was made to calculate the daily intake of fluoride from food and swallowed toothpaste. Methods Daily alimentary fluoride intake was measured in a group of 36 children with an average age of 4.75 years and an average weight of 20.69 kg at baseline, by means of a double plate method. This was repeated after six months. Parents recorded their child's diet over 24 hours and collected duplicated portions of food and beverages received by children during this period. Pooled samples of food and beverages were weighed and solid food samples were homogenized. Fluoride was quantitatively extracted from solid food samples by a microdiffusion method using hexadecyldisiloxane and perchloric acid. The content of fluoride extracted from solid food samples, as well as fluoride in beverages, was measured potentiometrically by means of a fluoride ion selective electrode. Results Average daily fluoride intake at baseline was 0.389 (SD 0.054) mg per day. Six months later it was 0.378 (SD 0.084) mg per day which represents 0.020 (SD 0.010) and 0.018 (SD 0.008) mg of fluoride respectively calculated per kg bw/day. When adding the values of unwanted fluoride intake from the toothpaste shown in the literature (0.17-1.21 mg per day) the estimate of the total daily intake of fluoride amounted to 0.554-1.594 mg/day and recalculated to the child's body weight to 0.027-0.077 mg/kg bw/day. Conclusions In the children studied, observed daily fluoride intake reached the threshold for safe fluoride intake. When adding the potential fluoride intake from swallowed toothpaste, alimentary intake reached the optimum range for daily fluoride intake. These results showed that

  12. Focus on Fluorides: Update on the Use of Fluoride for the Prevention of Dental Caries

    Science.gov (United States)

    Carey, Clifton M.

    2014-01-01

    Declarative Title: Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure. Background Fluoride is delivered to the teeth systemically or topically to aid in the prevention of dental caries. Systemic fluoride from ingested sources is in blood serum and can be deposited only in teeth that are forming in children. Topical fluoride is from sources such as community water, processed foods, beverages, toothpastes, mouthrinses, gels, foams, and varnishes. The United States Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) have proposed changes in their long standing recommendations for the amount of fluoride in community drinking water in response to concerns about an increasing incidence of dental fluorosis in children. Current research is focused on the development of strategies to improve fluoride efficacy. The purpose of this update is to inform the reader about new research and policies related to the use of fluoride for the prevention of dental caries. Methods Reviews of the current research and recent evidence based systematic reviews on the topics of fluoride are presented. Topics discussed include: updates on community water fluoridation research and policies; available fluoride in dentifrices; fluoride varnish compositions, use, and recommendations; and other fluoride containing dental products. This update provides insights into current research and discusses proposed policy changes for the use of fluoride for the prevention of dental caries. Conclusions The dental profession is adjusting their recommendations for fluoride use based on current observations of the halo effect and subsequent outcomes. The research community is focused on improving the efficacy of fluoride therapies thus reducing dental caries and lowering the amount of fluoride required for efficacy. PMID:24929594

  13. Urinary fluoride output in children following the use of a dual-fluoride varnish formulation.

    Science.gov (United States)

    Olympio, Kelly Polido Kaneshiro; Cardoso, Vanessa Eid da Silva; Bijella, Maria Fernanda Borro; Pessan, Juliano Pelim; Delbem, Alberto Carlos Botazzo; Buzalaf, Marília Afonso Rabelo

    2009-01-01

    This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to Duraphat. The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM). After 1-month interval (phase II), the same amount (0.2 mL) of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, Colgate) was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (papplication of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.

  14. Eukaryotic resistance to fluoride toxicity mediated by a widespread family of fluoride export proteins

    Science.gov (United States)

    Li, Sanshu; Smith, Kathryn D.; Davis, Jared H.; Gordon, Patricia B.; Breaker, Ronald R.; Strobel, Scott A.

    2013-01-01

    Fluorine is an abundant element and is toxic to organisms from bacteria to humans, but the mechanisms by which eukaryotes resist fluoride toxicity are unknown. The Escherichia coli gene crcB was recently shown to be regulated by a fluoride-responsive riboswitch, implicating it in fluoride response. There are >8,000 crcB homologs across all domains of life, indicating that it has an important role in biology. Here we demonstrate that eukaryotic homologs [renamed FEX (fluoride exporter)] function in fluoride export. FEX KOs in three eukaryotic model organisms, Neurospora crassa, Saccharomyces cerevisiae, and Candida albicans, are highly sensitized to fluoride (>200-fold) but not to other halides. Some of these KO strains are unable to grow in fluoride concentrations found in tap water. Using the radioactive isotope of fluoride, 18F, we developed an assay to measure the intracellular fluoride concentration and show that the FEX deletion strains accumulate fluoride in excess of the external concentration, providing direct evidence of FEX function in fluoride efflux. In addition, they are more sensitive to lower pH in the presence of fluoride. These results demonstrate that eukaryotic FEX genes encode a previously unrecognized class of fluoride exporter necessary for survival in standard environmental conditions. PMID:24173035

  15. On the wedding of certain dynamical processes in disordered complex materials to the theory of stable (Lévy) distribution functions

    Science.gov (United States)

    Montroll, Elliott W.; Shlesinger, Michael F.

    We review and comment on styles of applied mathematics before exhibiting our own in regard to relating the theory of Lévy's stable distributions to dynamic processes in complex disordered materials. Lévy's probability distributions have long tails, infinite moments and elegant scaling properties. Our first example connects intermittant currents in certain xerographic films to a Lévy distribution of waiting times for the jumping of charges out of a distribution of deep traps. We then extend our analysis from transport to electron-hole recombination reactions in amorphous materials. A Lévy distribution of first passage times appears both in this recombination problem as well as in the dielectric relaxation phenomena described by the Williams-Watts formula. Lastly, the most famous scaling problem, "1/f noise", is shown to be related to a log-normal distribution of relaxation times. We derive the log-normal distribution in a generic fashion and show it to be a limiting form of a Lévy distribution.

  16. Change of urinary fluoride and bone metabolism indicators in the endemic fluorosis areas of southern china after supplying low fluoride public water

    Science.gov (United States)

    2013-01-01

    indicators related to UF. While assessing the temporal trend of different abnormal bone indicators after the intervention, bone mineral density showed the most stable and the lowest abnormal rates over time. Conclusions Our results suggest that supplying low fluoride public water in Southern China is successful as measured by the reduction of fluoride in water and urine, and changes in various bone indicators to normal levels. A comparison of four bone indicators showed CT and BGP to be the most sensitive indicators. PMID:23425550

  17. Groundwater fluoride contamination: A reappraisal

    Directory of Open Access Journals (Sweden)

    Amlan Banerjee

    2015-03-01

    Full Text Available Dissolution of fluorite (CaF2 and/or fluorapatite (FAP [Ca5(PO43F], pulled by calcite precipitation, is thought to be the dominant mechanism responsible for groundwater fluoride (F− contamination. Here, one dimensional reactive–transport models are developed to test this mechanism using the published dissolution and precipitation rate kinetics for the mineral pair FAP and calcite. Simulation results correctly show positive correlation between the aqueous concentrations of F− and CO32− and negative correlation between F− and Ca2+. Results also show that precipitation of calcite, contrary to the present understanding, slows down the FAP dissolution by 106 orders of magnitude compared to the FAP dissolution by hydrolysis. For appreciable amount of fluoride contamination rock–water interaction time must be long and of order 106 years.

  18. Computer simulation of superionic fluorides

    CERN Document Server

    Castiglione, M

    2000-01-01

    experimentally gives an indication of the correlations between nearby defects is well-reproduced. The most stringent test of simulation model transferability is presented in the studies of lead tin fluoride, in which significant 'covalent' effects are apparent. Other similarly-structured compounds are also investigated, and the reasons behind the adoption of such an unusual layered structure, and the mobility and site occupation of the anions is quantified. In this thesis the nature of ion mobility in cryolite and lead fluoride based compounds is investigated by computer simulation. The phase transition of cryolite is characterised in terms of rotation of AIF sub 6 octahedra, and the conductive properties are shown to result from diffusion of the sodium ions. The two processes appear to be unrelated. Very good agreement with NMR experimental results is found. The Pb sup 2 sup + ion has a very high polarisability, yet treatment of this property in previous simulations has been problematic. In this thesis a mor...

  19. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    Science.gov (United States)

    Fries, B.A.

    1959-11-10

    A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

  20. A comparison of two methods for the evaluation of the daily urinary fluoride excretion in Romanian pre-school children.

    Science.gov (United States)

    Székely, M; Bánóczy, J; Fazakas, Z; Hobai, S; Villa, A

    2008-03-01

    To compare two different methods of estimating daily fluoride urinary excretion in pre-school children under stable fluoride intake conditions. Thirty-five healthy kindergarten children, permanent residents of Targu-Mures, Romania, where the average drinking water fluoride concentration is 0.12 mg F/L, participated on two separate occasions, when they were aged 4-6 and 5-7 years, respectively in the collection of a) a mid-morning spot urine sample and b) a 16-h time-controlled urine sampling. In case a), the ratio of concentrations of fluoride and creatinine were measured, while in case b) the rates of fluoride excretion in two separate 8-hour periods were used to estimate the 24-hour fluoride urinary excretion. The estimated average daily fluoride urinary excretion values (S.D.) were 0.318 (0.182) mg F/day for method a) and 0.341 (0.193) mg F/day for method b). These values were not significantly different (Mann-Whitney U test; p = 0.49). The estimated daily fluoride doses were 0.040 (0.021) and 0.043 (0.022) mg F/kg body weight/day, respectively. The latter values were not significantly different (Mann Whitney U test; p = 0.38). Results obtained suggest that under stable F-intake conditions the estimation of the daily fluoride urinary excretion by means of a mid-morning spot urine sample yields comparable results to those obtained with the more involved method of separate, two 8 h (16 h) time-controlled urine sampling recommended by the WHO. Use of spot urine sampling appears to be particularly useful for epidemiological studies.

  1. Thermodynamic data for uranium fluorides

    International Nuclear Information System (INIS)

    Leitnaker, J.M.

    1983-03-01

    Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF 4 and UF 6 , including UF 4 (solid and gas), U 4 F 17 (solid), U 2 F 9 (solid), UF 5 (solid and gas), U 2 F 10 (gas), and UF 6 (solid, liquid, and gas). Included are thermal function - the heat capacity, enthalpy, and free energy function, heats of formation, and vaporization behavior

  2. Compton profile of calcium fluoride

    International Nuclear Information System (INIS)

    Vijayakumar, R.; Rajasekaran, L.; Ramamurthy, N.; Shivaramu

    2003-01-01

    Full text: The Compton profile of polycrystalline calcium fluoride is measured using 661.6 keV γ- radiation from a 137 Cs source. The experimental data are compared with HF-LCAO model calculation computed using CRYSTAL98 program, Hartree-Fock free atom theoretical values and with the other available experimental data. Experimental results are found to be in good agreement with the HF-LCAO model calculations and in qualitative agreement with Hartree-Fock free atom theoretical values

  3. A new approach to prepare nanoscopic rare earth metal fluorides: the fluorolytic sol-gel synthesis of ytterbium fluoride.

    Science.gov (United States)

    Schmidt, L; Dimitrov, A; Kemnitz, E

    2014-06-25

    A new approach for the preparation of approx. 5 nm sized ytterbium fluoride nanoparticles based on the fluorolytic sol-gel route is reported. DLS, TEM, IR and XRD were used to characterize the particles as well as the aging behavior of the sols. Furthermore, a new Yb(III) complex was isolated from the precursor solution and characterized by X-ray single crystal structure determination.

  4. Fluoride Supplementation Adherence and Barriers in a Community Without Water Fluoridation.

    Science.gov (United States)

    Flood, Shannon; Asplund, Karin; Hoffman, Benjamin; Nye, Allison; Zuckerman, Katharine E

    2017-04-01

    To prevent early childhood caries, the American Dental Association recommends oral fluoride supplementation for children in communities lacking water fluoridation who are at high caries risk. However, patient adherence to oral fluoride supplementation has not been studied in this population. This study assessed adherence to oral fluoride and barriers to adherence in a community lacking water fluoridation. A self-administered survey was completed in a systematic sample of 209 parents of children aged 6 months to 4 years, during a primary care visit in an urban academic medical center. Participants reported frequency of administering oral fluoride to their children, as well as agreement or disagreement with proposed barriers to supplementation. Bivariate and multivariate analyses were used to assess adherence with oral supplementation and the association of barriers to supplementation and child receipt of fluoride on the day before. More than half of parents either had not or did not know if their child had received fluoride on the day before. Approximately 1 in 4 of parents had given fluoride in 0 of the previous 7 days. Difficulty remembering to give fluoride and agreeing that the child does not need extra fluoride were associated with not receiving fluoride on the day before. Adherence to oral fluoride supplementation in the primary care setting is low. Difficulty remembering to give fluoride daily is the greatest barrier to adherence. Further research on interventions to reduce common barriers is needed to increase fluoride administration and reduce early childhood caries in communities lacking water fluoridation. Copyright © 2016 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

  5. Assessing fluoride levels of carbonated soft drinks.

    Science.gov (United States)

    Heilman, J R; Kiritsy, M C; Levy, S M; Wefel, J S

    1999-11-01

    Dental fluorosis occurs as a result of excessive total fluoride intake during tooth development. Some children may receive substantial intake from soft drinks, but few studies have reported fluoride levels in soft drinks. The authors examined the fluoride concentrations of 332 soft drinks. Soft drinks were purchased from Iowa grocery stores. To identify production sites, the authors recorded product details and batch numbers. After decarbonating the drinks, the authors assayed samples for fluoride content using a fluoride ion-specific electrode, and reported the results in parts per million, or ppm, using appropriate standards and duplicate assessments. Descriptive statistics were used to summarize the findings. The fluoride levels of the products ranged from 0.02 to 1.28 ppm, with a mean level of 0.72 ppm. Fluoride levels exceeded 0.60 ppm for 71 percent of the products. Results varied substantially by production site, even within the same company and for the same product. There were no substantial differences between flavors or between diet and regular soft drinks. The majority of soft drinks had fluoride levels exceeding 0.60 ppm. Variation in fluoride levels probably is due largely to the different water sources used in production. With no fluoride levels marked on the soft drink products or easily available from the manufacturers, it is not possible for clinicians or consumers to directly estimate fluoride ingestion from carbonated beverages. Therefore, to reduce the risk of dental fluorosis, dental and medical practitioners should be cautious about prescribing dietary fluoride supplements to preschool-aged children in nonfluoridated areas who consume large quantities of carbonated soft drinks.

  6. Estuarine response of fluoride - Investigations in Azhikode Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Balachandran, K.K.; Joseph, T.; Sankaranarayanan, V.N.

    Concentrations of fluoride in Azhikode estuarine region (Kerala, India) were measured as a function of chlorinity during the different seasons. The type of behaviour indicated that fluoride was regulated by sea water incursion alone. Fluoride...

  7. Study of fluoride in polluted and unpolluted estuarine environments

    Digital Repository Service at National Institute of Oceanography (India)

    Zingde, M.D.; Mandalia, A.V.

    Mindhola river estuary, which receives industrial waste containing high concentrations of fluoride, and Purna River estuary, which is free from fluoride contamination, have been investigated. While fluoride behaved conservatively in Purna River...

  8. System of fluorides and chromates of cesium and lead

    International Nuclear Information System (INIS)

    Belyaev, I.N.; Revina, O.Ya.

    1980-01-01

    The triple mutual system of CsF-Cs 2 CrO 4 -PbF 2 -PbCrO 4 hav been investigated by the visual-polythermal and, in part, by the thermographical methods with a view to find out the nature of reactions occurring in recrystallization of cesium and lead fluorides and chromates from a melt. The parameters of six nonvariant points have been determined. The system may be classified as an irreversibly-mutual stable cross-section diagonal analysis [ru

  9. Contribution to the study by infrared spectroscopy of addition compounds of boron fluorides and ethers-oxides or organic sulphides

    International Nuclear Information System (INIS)

    Le Calve, Jacques

    1964-01-01

    This research thesis reports the study of complexes formed with boron fluoride and ethers or organic sulphides. In a first part, the author recalls vibration modes of free boron fluoride and of this compound in a complex. In the next parts, he reports the analysis of infrared spectra of groups present in addition compounds (between 400 and 1500 cm -1 ). He discusses spectrum modifications of electron donors by formation of a coordination bound. Experimental conditions are presented in appendix [fr

  10. Fluoride and Oral Health

    DEFF Research Database (Denmark)

    O'Mullane, D M; Baez, R J; Jones, S

    2016-01-01

    The discovery during the first half of the 20th century of the link between natural fl uoride, adjusted fl uoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fl uoride in improving oral health...... including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fl uorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision...... of the original 1994 document, again using the expertise of researchers from the extensive fi elds of knowledge required to successfully implement complex interventions such as the use of fl uorides to improve dental and oral health. Financial support for research into the development of these new fl uoride...

  11. Urinary fluoride output in children following the use of a dual-fluoride varnish formulation

    Directory of Open Access Journals (Sweden)

    Kelly Polido Kaneshiro Olympio

    2009-06-01

    Full Text Available OBJECTIVE: This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to DuraphatTM. MATERIAL AND METHODS: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I, children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM TM. After 1-month interval (phase II, the same amount (0.2 mL of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, ColgateTM was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (p<0.05. RESULTS: There were significant differences in the urinary fluoride output between phases I and II. The use of Duofluorid XII did not significantly increase the urinary fluoride output, when compared to baseline levels. The application of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. CONCLUSIONS: The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.

  12. Coupling Activity-Based Detection, Target Amplification, Colorimetric and Fluorometric Signal Amplification, for Quantitative Chemosensing of Fluoride Generated from Nerve Agents.

    Science.gov (United States)

    Sun, Xiaolong; Reuther, James F; Phillips, Scott T; Anslyn, Eric V

    2017-03-17

    The G-class nerve agents, which include sarin, soman, and cyclosarin, react readily with nucleophilic reagents to produce fluoride. Thus, a chemosensing protocol has been designed for these agents that pairs the nucleophilic reactivity of oximates for generating fluoride with an autoinductive target amplification reaction to amplify the quantity of fluoride for facile colorimetric and fluorescent optical quantification. The chemosensing protocol was demonstrated by using the nerve agent surrogate diisopropyl fluorophosphate (DFP) and benzaldoxime as the nucleophile. Autoinductive fluoride amplification responds to fluoride released from DFP by amplifying the fluoride concentration and a yellow reporter molecule. The reporter is a conjugated oligomer with a nominal repeating unit that originates from 4-aminobenzaldehyde. Exposure of the amplified fluoride to a fluoride-specific ratiometric fluorescent reporter provides a fluorescent readout, in which three fluorophores are generated per fluoride. Both colorimetric and fluorescent readouts enable quantitative assays with low micromolar limits of detection for fluoride resulting from DFP. More importantly, this work demonstrates the successful merging of multiple complex reactions for achieving selective, sensitive, and quantitative chemosensing. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. CORRELATION AMONG FLUORIDE AND METALS IN IRRIGATION ...

    African Journals Online (AJOL)

    Preferred Customer

    include the following: the industrial production and use of chemicals and phosphate fertilizers. Phosphate ... and distribution pattern fluoride in Ethiopian Rift Valley water [7, 8], fluoride binding capacity of different types .... sample was transferred in to labeled, pre-cleaned plastic bottles after rinsing with the water sample and ...

  14. Biomonitoring Equivalents for interpretation of urinary fluoride.

    Science.gov (United States)

    Aylward, L L; Hays, S M; Vezina, A; Deveau, M; St-Amand, A; Nong, A

    2015-06-01

    Exposure to fluoride is widespread due to its natural occurrence in the environment and addition to drinking water and dental products for the prevention of dental caries. The potential health risks of excess fluoride exposure include aesthetically unacceptable dental fluorosis (tooth mottling) and increased skeletal fragility. Numerous organizations have conducted risk assessments and set guidance values to represent maximum recommended exposure levels as well as recommended adequate intake levels based on potential public health benefits of fluoride exposure. Biomonitoring Equivalents (BEs) are estimates of the average biomarker concentrations corresponding to such exposure guidance values. The literature on daily urinary fluoride excretion rates as a function of daily fluoride exposure was reviewed and BE values corresponding to the available US and Canadian exposure guidance values were derived for fluoride in urine. The derived BE values range from 1.1 to 2.1mg/L (1.2-2.5μg/g creatinine). Concentrations of fluoride in single urinary spot samples from individuals, even under exposure conditions consistent with the exposure guidance values, may vary from the predicted average concentrations by several-fold due to within- and across-individual variation in urinary flow and creatinine excretion rates and due to the rapid elimination kinetics of fluoride. Thus, the BE values are most appropriately applied to screen population central tendency estimates for biomarker concentrations rather than interpretation of individual spot sample concentrations. Copyright © 2015. Published by Elsevier Inc.

  15. Potentiometric Determination of Fluoride Concentration in Beers.

    Science.gov (United States)

    Jaudenes, Juan Ramón; Hardisson, Arturo; Paz, Soraya; Rubio, Carmen; Gutiérrez, Angel José; Burgos, Antonio; Revert, Consuelo

    2018-01-01

    Beer is a widely consumed drink throughout the world, and because its manufacture involves the use of water, beer can be, in some cases, a source of fluorides. For this reason, the objective of this study was to determine the concentration of fluorides in 50 samples of beers from different sources sold in two different types of container (aluminum can and glass bottle). The possible significant differences between the different types of packaging and the intake of fluoride from the consumption of these beers were evaluated. The concentration of fluoride in beers has been determined using the potentiometric method of fluoride determination by standard addition. The concentration of fluoride ranged between 0.06 and 1.77 mg/L. In general, the concentration was below 1 mg/L, except for three beer samples from Ireland and the USA, whose concentration was over 1.5 mg/L. No significant differences were found between the types of packaging. The contribution of fluoride to the diet from beer consumption is not high (<27%); however, it is necessary to warn consumers whenever they are in areas of high concentrations of fluoride in the water supply.

  16. Hydrogeochemical framework and factor analysis of fluoride ...

    African Journals Online (AJOL)

    Fluoride contamination of groundwater within the Savelugu-Nanton District was assessed using hydrogeochemical framework and multivariate statistical approach. Eighty-one (No) boreholes were sampled for quality assessment in May and June 2008. The main objective of this study was to assess the fluoride levels in ...

  17. Fluoride ions vs removal technologies: A study

    Directory of Open Access Journals (Sweden)

    Jagvir Singh

    2016-11-01

    Full Text Available Literature reported that drinking water is a precious and scarce resource and it has to be protected and kept free from any kind of contamination. Further, it has to be used carefully without wasting. Literature also reported that fluoride bearing rocks are abundant in India, as a result, fluoride leaches out and contaminates the adjacent water and soil resources. A high concentration of fluoride ions in ground water increases up to more than 30 mg/L. This high concentration of fluoride ions causes many harmful and dangerous effects on our datum. Fluoride ions in larger quantities i.e. 20–80 mg/day taken over a period of 10–20 years result in crippling and skeletal fluorosis, severely damaging the bone. In the present scenario, there is a continuously increasing worldwide concern for the development of fluoride treatment technologies. Possibilities of reducing the high fluorine content in groundwater are by defluorination process/dilution with the surface water which is a very simple technique but the addition of Ca2+ ions to a solution in contact with fluorite when experimented in distilled water caused an appreciable decrease in fluoride concentration. In this review article, we emphasized the relationship between high concentrations of fluoride ions and their compounds and their health impact.

  18. Cycling of fluoride in a mangrove community near a fluoride emission source. [Avicennia marina (Forski)

    Energy Technology Data Exchange (ETDEWEB)

    Murray, F.

    1985-04-01

    A comparison of stands of immature grey mangroves, Avicennia marina (Forsk.) Vierh., growing near a fluoride emission source (Kooragang Island, Australia) and a relatively unpolluted area (Gosford) showed that A. marina can accumulate high concentrations of fluoride particularly in leaves, generally without visible injury. Fluoride input to the Kooragang Island ecosystem as bulk deposition of gaseous and particulate fluoride was found to be 0.31 g m/sup -2/ yr/sup -1/ and this varied with the distance and direction of each site in relation to fluoride emission sources. The above-ground biomass at both sites was practically identical but the fluoride concentration of leaves and branches were almost two orders of magnitude greater at Kooragang Island than at Gosford. A comparison of plant litterfall, fluoride concentration and fluoride deposition in litterfall at the Kooragang Island site and at Fullerton Cove showed that although litterfall rates were similar the rates of fluoride deposition in litterfall were also two orders of magnitude different due to the differences in fluoride concentration in all components of plant litter at the two sites. These litterfall rates are similar to other data reported for mangrove litter production at the same latitude. As a consequence of fluoride input by litterfall, wet deposition and dry deposition buffer-extractable fluoride concentrations in soils at Kooragang Island were generally within the range 4-15 ..mu..gF g/sup -1/. At Fullerton Cove and Gosford the buffer-extractable fluoride concentrations in soil were relatively constant with mean fluoride concentrations of 2.0 and 1.9 ..mu..gF g/sup -1/ respectively. Mangrove communities may export up to 25 kg ha /sup 1/ day /sup 1/ of detritus to estuarine food webs of commercial and ecological importance.

  19. Ion release from, and fluoride recharge of a composite with a fluoride-containing bioactive glass

    Science.gov (United States)

    Davis, Harry B.; Gwinner, Fernanda; Mitchell, John C.; Ferracane, Jack L.

    2014-01-01

    Objectives Materials that are capable of releasing ions such as calcium and fluoride, that are necessary for remineralization of dentin and enamel, have been the topic of intensive research for many years. The source of calcium has most often been some form of calcium phosphate, and that for fluoride has been one of several metal fluoride or hexafluorophosphate salts. Fluoride-containing bioactive glass (BAG) prepared by the sol-gel method acts as a single source of both calcium and fluoride ions in aqueous solutions. The objective of this investigation was to determine if BAG, when added to a composite formulation, can be used as a single source for calcium and fluoride ion release over an extended time period, and to determine if the BAG-containing composite can be recharged upon exposure to a solution of 5,000 ppm fluoride. Methods BAG 61 (61% Si; 31% Ca; 4% P; 3% F; 1% B) and BAG 81 (81% Si; 11% Ca; 4% P; 3% F; 1% B) were synthesized by the sol gel method. The composite used was composed of 50/50 Bis-GMA/TEGDMA, 0.8% EDMAB, 0.4% CQ, and 0.05% BHT, combined with a mixture of BAG (15%) and strontium glass (85%) to a total filler load of 72% by weight. Disks were prepared, allowed to age for 24 h, abraded, then placed into DI water. Calcium and fluoride release was measured by atomic absorption spectroscopy and fluoride ion selective electrode methods, respectively, after 2, 22, and 222 h. The composite samples were then soaked for 5 min in an aqueous 5,000 ppm fluoride solution, after which calcium and fluoride release was again measured at 2, 22, and 222 h time points. Results Prior to fluoride recharge, release of fluoride ions was similar for the BAG 61 and BAG 81 composites after 2 h, and also similar after 22 h. At the four subsequent time points, one prior to, and three following fluoride recharge, the BAG 81 composite released significantly more fluoride ions (pfluoride, although the BAG 81 composite was recharged more than the BAG 61 composite. The BAG 61

  20. Behaviour of metals and alloys in molten fluoride media

    International Nuclear Information System (INIS)

    Fabre, St.

    2009-01-01

    Fluoride salts are contemplated for Generation IV nuclear systems which structural materials need to resist corrosion at high temperatures. Corrosion of metals in molten fluorides has been investigated in support of the Molten Salt Reactor's development and led to an optimized alloy, Hastelloy-N, but it lacked fundamentals data for the comprehension of materials' degradation mechanisms. The main objective of this work is then to help with the understanding of the corrosion behaviour of nickel and its alloys in fluoride salts. An experimental method was built up using electrochemical techniques and enabled to investigate the thermochemical conditions of the media and the influence of different parameters (media, temperature and quantity of impurities) on the behaviour of the materials. Most tests were performed in LiF-NaF mixtures between 800 and 1000 C. Pure metals can be classified as follows: Cr ≤ Fe ≤ Ni ≤ Mo ≤ W in increasing stability order and two specific behaviours were evidenced: Cr and Fe corrode in the melt, whereas Ni, Mo and W are stable, underlining the significance level of the redox couple controlling the reactions in the mixture. Moreover, corrosion current densities increase with temperature, fluoro-acidity and the quantity of dissolved oxide in the melt. Binary Ni-Cr alloys were also tested; selective attack of Cr is first observed before both elements are oxidized. Combining thermochemical calculations and experimental results enables to propose an approach to establish an optimized composition for a stable alloy. Immersion tests were finally achieved in addition to the electrochemical tests: interpretations of both methods were compared and completed. (author)

  1. Fluoride removal by calcite: evidence for fluorite precipitation and surface adsorption.

    Science.gov (United States)

    Turner, Brett D; Binning, Philip; Stipp, S L S

    2005-12-15

    Fluoride contamination of groundwater, both anthropogenic and natural, is a major problem worldwide. In this study, fluoride removal by crushed limestone (99% pure calcite) was investigated by batch studies and surface-sensitive techniques from solutions with fluoride concentrations from 150 micromol/L (3 mg/L) to 110 mM (approximately 2100 mg/L). Surface-sensitive techniques, including atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) as well as zeta potential measurements, confirm that, in addition to precipitation reactions, adsorption of fluoride also occurs. Results indicate that fluoride adsorption occurs immediately over the entire calcite surface with fluorite precipitating at step edges and kinks, where dissolved Ca2+ concentration is highest. The PHREEQ geochemical model was applied to the observed data and indicates that existing models, especially at low fluoride concentrations and high pH (>7.5) are not equipped to describe this complex system, largely because the PHREEQ model includes only precipitation reactions, whereas a combination of adsorption and precipitation parameters are required.

  2. Thermodynamic data for uranium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Leitnaker, J.M.

    1983-03-01

    Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF/sub 4/ and UF/sub 6/, including UF/sub 4/ (solid and gas), U/sub 4/F/sub 17/ (solid), U/sub 2/F/sub 9/ (solid), UF/sub 5/ (solid and gas), U/sub 2/F/sub 10/ (gas), and UF/sub 6/ (solid, liquid, and gas). Included are thermal function - the heat capacity, enthalpy, and free energy function, heats of formation, and vaporization behavior.

  3. Niobium electrodeposition from molten fluorides

    International Nuclear Information System (INIS)

    Sartori, A.F.

    1987-01-01

    Niobium electrodeposition from molten alkali fluorides has been studied aiming the application of this technic to the processes of electrorefining and galvanotechnic of this metal. The effects of current density, temperature, niobium concentration in the bath, electrolysis time, substrate nature, ratio between anodic and cathodic areas, electrodes separation and the purity of anodes were investigated in relation to the cathodic current efficiency, electrorefining, electroplating and properties of the deposit and the electrolytic solution. The work also gives the results of the conctruction and operation of a pilot plant for refractory metals electrodeposition and shows the electrorefining and electroplating compared to those obtained at the laboratory scale. (author) [pt

  4. Measurement of fluoride in bone

    International Nuclear Information System (INIS)

    Mernagh, J.R.; Harrision, J.E.; Hancock, R.; McNeill, K.G.

    1977-01-01

    The fluorine concentration in bone biopsy samples was measured by neutron activation analysis. The fluorine content was expressed in terms of the calcium content. Samples were irradiated in a reactor to induce the 19 F(n,γ) 20 F and 48 Ca(n,γ) 49 Ca reactions and after rapid transport from the reactor the resulting activities were measured with a Ge(Li) detector. Reproducibility was better than 10% for the F/Ca ratio. The detection limit for F is 50 μg. This nondestructive technique will be used to assess the effect of fluoride therapy on bone metabolism of patients with idiopathic osteoporosis. (author)

  5. Determination of Fluoride in Different Toothpaste Formulations

    International Nuclear Information System (INIS)

    Kamau, N.G.; Njoroge, M.; Njau, M.

    1998-01-01

    Fluoride ion selective electrode was used to determine fluoride ion concentrations in seven brands of toothpaste. These were the only available formulations found in Kenya. The brands were classified into three groups-fluoridated, non fluoridated or not indicated. However, there was no independent indication of their quantitative composition. The analysed brands had fluoride content between 0.0033% and 0.096%. These values compared favourably with those obtained elsewhere. The calculated lowest limit of detection (LLD) was 0.01 ppmF- . The mean calibration curve gave a slope of of -50.0mV. which was not significantly different from the theoretical value of 5.88mV at 23 degrees celsius at 95% confidence level

  6. Fluoride Importance in Controlling Caries and Fluorosis

    Directory of Open Access Journals (Sweden)

    Gaurav Solanki

    2012-04-01

    Full Text Available The use of fluorides for oral health has always involved a balance between the protective benefit against dental caries and the risk of developing fluorosis. The link between fluoride and dental health was established to determining the causes of dental fluorosis or enamel mottling. Fluorosis in Indian children was highly prevalent in the early 1990s. Policy were introduced to control fluoride exposure and to reduce the prevalence of fluorosis. The study aimed of describing the prevalence, severity and risk factors for fluorosis, and to describe the trend of fluorosis among Indian children. The study also aimed of exploring the effect of the change in fluoride exposure on dental fluorosis and caries. Establishing an appropriate use of fluoride toothpaste could be successful in reducing fluorosis without a significant increase in caries experience.

  7. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1994-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets, with a few more additions - with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers - exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the foree of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc. (orig.)

  8. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1993-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

  9. Dental fluorosis and skeletal fluoride content as biomarkers of excess fluoride exposure in marsupials.

    Science.gov (United States)

    Death, Clare; Coulson, Graeme; Kierdorf, Uwe; Kierdorf, Horst; Morris, William K; Hufschmid, Jasmin

    2015-11-15

    Particulate and gaseous fluoride emissions contaminate vegetation near fluoride-emitting industries, potentially impacting herbivorous wildlife in neighboring areas. Dental fluorosis has been associated with consumption of fluoride-contaminated foliage by juvenile livestock and wildlife in Europe and North America. For the first time, we explored the epidemiology and comparative pathology of dental fluorosis in Australian marsupials residing near an aluminium smelter. Six species (Macropus giganteus, Macropus rufogriseus, Wallabia bicolor, Phascolarctos cinereus, Trichosurus vulpecula, Pseudocheirus peregrinus) demonstrated significantly higher bone fluoride levels in the high (n=161 individuals), compared to the low (n=67 individuals), fluoride areas (p<0.001). Necropsy examinations of all six species from the high-fluoride area near the smelter revealed dental lesions considered characteristic of dental fluorosis in eutherian mammals. Within the high-fluoride area, 67% of individuals across the six species showed dental enamel lesions, compared to 3% in the low-fluoride areas. Molars that erupted before weaning were significantly less likely to display pathological lesions than those developing later, and molars in the posterior portion of the dental arcade were more severely fluorotic than anterior molars in all six species. The severity of dental lesions was positively associated with increasing bone fluoride levels in all species, revealing a potential biomarker of excess fluoride exposure. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Fluoride in saliva and dental biofilm after 1500 and 5000 ppm fluoride exposure.

    Science.gov (United States)

    Staun Larsen, Line; Baelum, Vibeke; Tenuta, Livia Maria Andaló; Richards, Alan; Nyvad, Bente

    2017-09-01

    The aim of this randomized, double-blind, crossover study was to measure fluoride in saliva and 7-day-old biofilm fluid and biofilm solids after rinsing three times per day for 3 weeks with 0, 1500, or 5000 ppm fluoride (NaF). Following the 3-week wash-in/wash-out period, including 1 week of biofilm accumulation, saliva and biofilm samples were collected from 12 participants immediately before (background fluoride), and 10, 30, and 60 min after a single rinse. Biofilm samples were separated into fluid and solids, and samples were analyzed using a fluoride electrode (microanalysis). The background fluoride concentration was statistically significantly higher in the 5000 compared to the 1500 ppm F rinse group in all three compartments (22.3 and 8.1 μM in saliva, 126.8 and 58.5 μM in biofilm fluid, and 10,940 and 4837 μmol/kg in biofilm solids). The 1-h fluoride accumulation for the 5000 ppm F rinse was higher than for the 1500 ppm F rinse in all three compartments, although not statistically significant for saliva and biofilm solids. Regular exposure to 5000 ppm fluoride elevates background fluoride concentrations in saliva, biofilm fluid, and biofilm solids compared to 1500 ppm fluoride. Increasing the fluoride concentration almost 3.5 times (from 1500 to 5000 ppm) only elevates the background fluoride concentrations in saliva, biofilm fluid, and biofilm solids twofold. Even though fluoride toothpaste may be diluted by saliva, the results of the present study indicate that use of 5000 ppm fluoride toothpaste might lead to improved caries control.

  11. Fluorine-18 labeling of small molecules: the use of 18F-labeled aryl fluorides derived from no-carrier-added [18F]fluoride as labeling precursors.

    Science.gov (United States)

    Wuest, F

    2007-01-01

    The favourable long-half life, the ease of production and the low energy of the emitted positron make 18F an ideal radionuclide for PET imaging. Radiochemistry of 18F basically relies on two distinctive types of reactions: nucleophilic and electrophilic reactions. All syntheses of 18F-labeled radiotracers are based on either [18F]fluoride ion or [18F]fluorine gas as simple primary labeling precursors which are obtained directly from the cyclotron. They can be applied either directly to the radiosynthesis or they can be transformed into more complex labeling precursors enabling the multi-step build-up of organic tracer molecules. The topic of this review is a survey on the application of several 18F-labeled aryl fluorides as building blocks derived from no-carrier-added (n.c.a.) [18F] fluoride to build up small monomeric PET radiotracers at high specific radioactivity by multi-step synthesis procedures.

  12. Fluoride removal by adsorption on thermally treated lateritic soils ...

    African Journals Online (AJOL)

    The ability of lateritic soils to remove fluoride from water has been studied. Important issues considered in the study include the relation between the mineral composition of soils and their ability to remove fluoride, the effect of thermal treatment of the soil on fluoride removal; the predominant fluoride containing species ...

  13. Studies on the comparative effect of sodium fluoride on collagen ...

    African Journals Online (AJOL)

    Fluoride is an essential element for the normal development and growth of human beings. The main source of fluoride for humans is the intake of groundwater. At high levels, fluoride causes dental and skeletal fluorosis. In this study, control and sodium fluoride (NaF) treated groups of rats had significant (p < 0.05) higher ...

  14. Metal Fluoride Inhibition of a P-type H+ Pump

    Science.gov (United States)

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  15. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Science.gov (United States)

    Sauerheber, Richard

    2013-01-01

    The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings. PMID:23840230

  16. Synergistic effect of signaling from receptors of soluble platelet agonists and outside-in signaling in formation of a stable fibrinogen-integrin αIIbβ3-actin cytoskeleton complex.

    Science.gov (United States)

    Budnik, Ivan; Shenkman, Boris; Savion, Naphtali

    2015-01-01

    Thrombus formation in the injured vessel wall is a highly complex process involving various blood-born components that go through specific temporal and spatial changes as observed by intravital videomicroscopy. Platelets bind transiently to the developing thrombus and may either become stably incorporated into or disengage from the thrombus. The aim of the present study was to reveal the processes involved in the formation of a stable thrombus. Platelet-rich plasma and washed platelets were studied by the aggregometer. The aggregate stability was challenged by eptifibatide. Platelet Triton-insoluble fraction was prepared and the actin and αIIb content in the cytoskeleton was analyzed by western blot. Maximal actin polymerization is achieved 1min after platelet activation while maximal αIIbβ3-actin cytoskeleton association requires 5 to 10min of activation and fibrinogen-mediated platelet-to-platelet bridging. Thus, actin polymerization is dependent on platelet activation and requires neither αIIbβ3 integrin occupation nor platelet aggregation. Formation of a stable aggregate requires platelet activation for more than 1min, complete increase in actin cytoskeleton fraction and partial association of αIIbβ3 with the actin cytoskeleton. However, direct αIIbβ3 activation is not sufficient for cytoskeleton complex formation. Thus, stable αIIbβ3-fibrinogen interaction, representing stable aggregate, is achieved after more than 1min agonist activation, involving inside-out and outside-in signaling but not after direct integrin activation, involving only outside-in signaling. Formation of a stable fibrinogen-αIIbβ3-actin cytoskeleton complex is the result of the combined effect of platelet stimulation by soluble agonists, activation of αIIbβ3, fibrinogen binding and platelet-to-platelet bridging. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Fluoride

    Science.gov (United States)

    Advance White® ... Simply White® ... In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has ...

  18. Recognition and sensing of fluoride anion.

    Science.gov (United States)

    Cametti, Massimo; Rissanen, Kari

    2009-05-28

    Fluoride anion recognition is attracting a mounting interest in the scientific community due to its duplicitous nature. It is a useful chemical for many industrial applications, and it has been used in human diet, but, recently it has been accused for several human pathologies. Here we describe the ample panorama of different approaches the chemists world-wide have employed to face the challenge of fluoride binding, and we outline some of the research which in our view can contribute to the development of this field, especially when fluoride binding has to be achieved in highly competitive protic solvents and water.

  19. Fluoride exposure and reported learning disability diagnosis among Canadian children: Implications for community water fluoridation.

    Science.gov (United States)

    Barberio, Amanda M; Quiñonez, Carlos; Hosein, F Shaun; McLaren, Lindsay

    2017-09-14

    Recent studies have connected increased fluoride exposure with increased risk of neurodevelopmental-related outcomes, such as ADHD (attention deficit hyperactivity disorder) and lower IQ in children. Our primary objective was to examine the association between fluoride exposure and reported diagnosis of a learning disability among a population-based sample of Canadian children aged 3-12 years. We analyzed data from Cycles 2 and 3 of the Canadian Health Measures Survey. Four measures of fluoride exposure were available: 1) urinary fluoride (μmol/L), 2) creatinine-adjusted urinary fluoride (μmol/mmol), 3) specific gravity-adjusted urinary fluoride (μmol/L), and 4) fluoride concentration of tap water (mg/L) (Cycle 3 only). Diagnosis of a learning disability (yes/no) was based on parental- or self-report. Associations were examined using logistic regression (where possible), unadjusted and adjusted for covariates. When Cycles 2 and 3 were examined separately, reported learning disability diagnosis was not significantly associated with any measure of fluoride exposure in unadjusted or adjusted models. When Cycles 2 and 3 were combined, a small but statistically significant effect was observed such that children with higher urinary fluoride had higher odds of having a reported learning disability in the adjusted model (p = 0.03). However, the association was not observed in models that used creatinine-adjusted urinary fluoride and specific gravity-adjusted urinary fluoride, which are believed to be more accurate measures due to their correction for urinary dilution. Overall, there did not appear to be a robust association between fluoride exposure and parental- or self-reported diagnosis of a learning disability among Canadian children.

  20. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  1. Chlorophytum susceptibility to fluoride injury

    Energy Technology Data Exchange (ETDEWEB)

    Matkin, O.A.

    1977-01-01

    Experiments were performed to investigate the cause of leaf tip burn in Chlorophytum using varying concentrations of F. Only one case of superimposed fluoride exposure was evaluated. All other mediums were considered safely low in F. Analyses of foliage at the conclusion of the trials showed relatively low and safe concentrations of F in all treatments. The most important observation was that none of the treatments produced any measurable degree of leaf tip burn. The surprising result was that irrigation water fortified with F failed to produce any adverse reaction. It was concluded that much of the injury to Chlorophytum previously attributed to F was probably due to unfavorable cultural conditions, rather than F.

  2. REDUCTION OF FLUORIDE TO METAL

    Science.gov (United States)

    Carlson, O.N.; Schmidt, F.A.; Spedding, F.H.

    1960-08-30

    A process is given for making yttrium metal by reducing yttrium fluoride with calcium plus magnesium. Calcium is added in an excess of from 10 to 20% and magnesium in a quantity to yield a magnesium--yttrium alloy containing from 12 to 25% magnesium when the reaction mass is heated in an inert atmosphere at from 900 to 1106 deg C, but preferably above the melting point of the alloy. Calcium chloride may be added so as to obtain a less viscous slag containing from 30 to 60% calcium chloride. After removal of the slag the alloy is vacuum-heated at about 1100 deg C for volatilization of the magnesium and calcium.

  3. Detection of trace fluoride in serum and urine by online membrane-based distillation coupled with ion chromatography.

    Science.gov (United States)

    Lou, Chaoyan; Guo, Dandan; Wang, Nani; Wu, Shuchao; Zhang, Peimin; Zhu, Yan

    2017-06-02

    An online membrane-based distillation (MBD) coupled with ion chromatography (IC) method was proposed for automatic detection of trace fluoride (F - ) in serum and urine samples. The system consisted of a sample vessel, a lab-made membrane module and an ion chromatograph. Hydrophobic polytetrafluoroethylene (PTFE) hollow fiber membrane was used in MBD which was directly performed in serum and urine samples to eliminate the matrix interferences and enrich fluoride, while enabling automation. The determination of fluoride in biological samples was carried out by IC with suppressed conductometric detection. The proposed method feasibly determined trace fluoride in serum and urine matrices with the optimized parameters, such as acid concentration, distillation temperature, and distillation time, etc. Fluoride exhibited satisfactory linearity in the range of 0.01-5.0mg/L with a correlation coefficient of 0.9992. The limit of detection (LOD, S/N=3) and limit of quantification (LOQ, S/N=10) were 0.78μg/L and 2.61μg/L, respectively. The relative standard deviations of peak area and peak height were all less than 5.15%. The developed method was validated for the determination of fluoride in serum and urine with good spiked recoveries ranging between 97.1-101.9%. This method also can be proposed as a suitable alternative for the analysis of fluoride in other complex biological samples. Copyright © 2017. Published by Elsevier B.V.

  4. Fluoride release, recharge and mechanical property stability of various fluoride-containing resin composites.

    Science.gov (United States)

    Naoum, S; Ellakwa, A; Martin, F; Swain, M

    2011-01-01

    To determine the fluoride release and recharge of three fluoride-containing resin composites when aged in deionized water (pH 6.5) and lactic acid (pH 4.0) and to assess mechanical properties of these composites following aging. Three fluoride-containing resin composites were analyzed in this study; a new giomer material named Beautifil II, Gradia Direct X, and Tetric EvoCeram. A glass ionomer cement, Fuji IX Extra, was also analyzed for comparison. Specimens were fabricated for two test groups: group 1 included 10 disc specimens initially aged 43 days in deionized water (five specimens) and lactic acid (five specimens). The fluoride release from these specimens was measured using a fluoride-specific electrode on nine specific test days during the aging period. Following 49 days of aging, each specimen was recharged in 5000 ppm neutral sodium fluoride solution for 5 minutes. Specimen recharge was then repeated on a weekly basis for 3 weeks. The subsequent fluoride rerelease was measured at 1, 3, and 7 days after each recharge episode. Group 2 included six disc specimens aged for 3 months in deionized water (three specimens) and lactic acid (three specimens). The hardness and elastic modulus of each specimen was measured using nano-indentation at intervals of 24 hours, 1 month, and 3 months after fabrication. Two-way factorial analysis of variance (ANOVA) and post-hoc (Tukey) testing was used to assess the influence of storage media (two levels) and composite type (three levels) on the fluoride release, fluoride rerelease, hardness, and elastic modulus of the assessed materials. The level of significance was set at p=0.05. All three composites demonstrated fluoride release and recharge when aged in both deionized water and lactic acid. The cumulative fluoride released from Beautifil II into both media was substantially greater than the fluoride released from Gradia Direct X and Tetric EvoCeram after 43 days aging and was significantly (ptest) greater during several

  5. Neither hollow-fibre membrane filters nor activated-charcoal filters remove fluoride from fluoridated tap water.

    Science.gov (United States)

    Konno, Hideki; Yaegaki, Ken; Tanaka, Tomoko; Sato, Tsutomu; Itai, Kazuyoshi; Imai, Toshio; Murata, Takatoshi; Herai, Mayumi

    2008-06-01

    Previous reports of the reduction of fluoride concentrations in fluoridated water by domestic water treatment systems have indicated that further supplementation with fluoride is required. However, the absorption of fluoride by filters has not yet been directly identified. If these filters do not absorb fluoride, further fluoride supplementation may increase fluorosis. In this study, we determined whether filtering systems absorb fluoride ions. We directly measured the amounts of fluoride absorbed by activated-carbon filters or hollow-fibre membrane filters using pyrohydrolysis of the filters and flow-injection analysis, the sensitivity of which is more than 100 times greater than that of conventional methods. We made fluoride solutions of pure or tap water and determined changes in fluoride concentration as a result of filtering with a fluoride electrode. Hollow-fibre membrane filters did not affect fluoride concentrations in the fluoridated water, but activated-carbon filters removed some fluoride, especially from the pure-water solution. Filtering a pure-water solution with a fluoride concentration of 0.8 mg F/L reduced the fluoride concentration until 210 L of the solution had been filtered. However, filtering a tap-water solution of 0.8 mg F/L reduced the fluoride concentration only until 8 L had been filtered. The concentration of absorbed fluoride in the filter at 10 L of filtration was 4.7 mg/kg activated carbon. Further fluoride supplementation of fluoridated water should not be necessary, regardless of whether an activated-carbon or hollow-fibre membrane filter is installed on a domestic water treatment system.

  6. Removal of fluoride from aqueous nitric acid

    International Nuclear Information System (INIS)

    Pruett, D.J.; Howerton, W.B.; Mailen, J.C.

    1981-06-01

    Several methods for removing fluoride from aqueous nitric acid were investigated and compared with the frequently used aluminum nitrate-calcium nitrate (Ca 2+ -Al 3+ ) chemical trap-distillation system. Zirconium oxynitrate solutions were found to be superior in preventing volatilization of fluoride during distillation of the nitric acid, producing decontamination factors (DFs) on the order of 2 x 10 3 (vs approx. 500 for the Ca 2+ -Al 3+ system). Several other metal nitrate systems were tested, but they were less effective. Alumina and zirconia columns proved highly effective in removing HF from HF-HNO 3 vapors distilled through the columns; fluoride DFs on the order of 10 6 and 10 4 , respectively, were obtained. A silica gel column was very effective in adsorbing HF from HF-HNO 3 solutions, producing a fluoride DF of approx. 10 4

  7. Fluoride method for silicon determination i silicovadium

    International Nuclear Information System (INIS)

    Komarnitskaya, N.N.; Sergeev, K.I.; Shamraj, Z.Ya.

    1977-01-01

    The method used was based on formation of a silicon-potassium fluoride-sodium sediment in strongly acid medium in the presence of excess potassium chloride which decreased the sediment solubility. The sediment was dissolved in hot water to titrate the resultant hydrofluoric acid with a caustic potash solution in the presence of phenolphthalein. Gravity hydrochloric and volumetric fluoride methods were used to compare the results of silicon estimation

  8. FLUORIDE LEVELS IN COMMERCIALLY AVAILABLE RICE IN ...

    African Journals Online (AJOL)

    Preferred Customer

    2013-05-05

    May 5, 2013 ... E-mail: bscv2006@yahoo.com. FLUORIDE LEVELS IN .... Varying levels of several metals such as Na, K, Ca, Mg, Fe, Mn, Zn, Ni, Co, Cd, and Pb [21, 28-. 33] in different types of rice .... was 0.2 mg/L, and in tap water added fluoride to the levels of 3, 6 and 10 mg F/L. Difference in amount of water used and ...

  9. Recovery of fluoride ion selective electrode

    International Nuclear Information System (INIS)

    Monteiro, R.P.G.

    1988-01-01

    A recovery procedure of fluoride ion selective electrode based upon the body radiography of inactive electrode and introduction of suitable internal regeneration solution, is developed. The recovered electrode was tested in standard solutions of fluoride ions (10 sup5) to 10 -1M showing as good performance as the new one. The fluor determination by potentiometric measurements with selective electrode is used in nuclear fuel cycle for quality control of thorium and uranium mixed oxide pellets and pellets of uranium dioxides. (author) [pt

  10. Well Waters Fluoride in Enugu, Nigeria

    Directory of Open Access Journals (Sweden)

    ISI Ogbu

    2012-03-01

    Full Text Available Abnormal fluoride levels in drinking water have been associated with adverse health effects. To determine the fluoride content of well waters in Enugu, southeastern Nigeria, water samples from 50 artisan wells chosen by multistage sampling procedure from the 5 zones of Enugu municipality were analyzed in duplicates for their fluoride content. The zonal mean values were 0.60, 0.70, 0.62, 0.62, and 0.63 mg/L for Abakpa Nike, Achara Layout, Obiagu/ Ogui, Trans Ekulu and Uwani, respectively (p<0.05. The mean value for the whole city was 0.63 mg/L. Although, the mean level of fluoride recorded in this study is currently within safe limits (1.5 mg/L, WHO 2011, it is important to monitor continuously the fluoride content of well waters in the municipality in view of the increasing industrial activities going on in the city and heavy reliance on well water for domestic purposes and the widespread use of consumer products containing fluoride.

  11. THE USE OF FLUORIDE AND ITS EFFECT ON HEALTH

    Directory of Open Access Journals (Sweden)

    Domen Kanduti

    2016-07-01

    Full Text Available Appropriate oral health care is fundamental for any individual’s health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. Fluoride occurs naturally in our environment and is always present in our lives. However, the concentration differs from area to area. Exposure can occur through diet, respiration and fluoride supplements. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Drinking water in Slovenia is not fluoridated; the amount of naturally present fluoride is very low. Fluoride can be toxic in extremely high concentrations. The most important effect of fluoride on caries incidence is through its role in the process of remineralisation and demineralisation of tooth enamel. The European Academy of Paediatric Dentistry (EAPD recommends a preventive topical use of fluoride supplements because of their cariostatic effect. 

  12. Anion exchange behaviour of Zr, Hf, Nb, Ta and Pa as homologues of RF and Db in fluoride medium

    Energy Technology Data Exchange (ETDEWEB)

    Monroy G, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Trubert, D.; Brillard, L.; Hussonnois, M.; Constantinescu, O.; Le Naour, C., E-mail: fabiola.monroy@inin.gob.m [Institut de Physique Nucleaire, F-91406 Orsay, France (France)

    2010-07-01

    Studies of the chemical property of trans actinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behaviour of rutherfordium, RF (element 104), dub nium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta an Pa, homologues of RF and Db, were studied in NH{sub 4}F/HClO{sub 4} medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from K{sub d} obtained at different F{sup -} and H{sup +} concentrations. The anionic complexes: [Zr(Hf)F{sub 5}]{sup -}, [Zr(Hf)F{sub 6}]{sup 2-}, [Zr(Hf)F{sub 7}]{sup 3-}, [Ta(Pa)F{sub 6}]{sup -}, [Ta(Pa)F{sub 7}]{sup 2-}, [Ta(Pa)F{sub 8}]{sup 3-}, [NbOF{sub 4}]{sup -} and [NbOF{sub 5}]{sup 2-} are present as predominant species in the HF range over investigation. (Author)

  13. Anion exchange behaviour of Zr, Hf, Nb, Ta and Pa as homologues of RF and Db in fluoride medium

    International Nuclear Information System (INIS)

    Monroy G, F.; Trubert, D.; Brillard, L.; Hussonnois, M.; Constantinescu, O.; Le Naour, C.

    2010-01-01

    Studies of the chemical property of trans actinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behaviour of rutherfordium, RF (element 104), dub nium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta an Pa, homologues of RF and Db, were studied in NH 4 F/HClO 4 medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from K d obtained at different F - and H + concentrations. The anionic complexes: [Zr(Hf)F 5 ] - , [Zr(Hf)F 6 ] 2- , [Zr(Hf)F 7 ] 3- , [Ta(Pa)F 6 ] - , [Ta(Pa)F 7 ] 2- , [Ta(Pa)F 8 ] 3- , [NbOF 4 ] - and [NbOF 5 ] 2- are present as predominant species in the HF range over investigation. (Author)

  14. Electrochemical Extraction of Rare Earth Metals in Molten Fluorides : Conversion of Rare Earth Oxides into Rare Earth Fluorides Using Fluoride Additives

    NARCIS (Netherlands)

    Abbasalizadeh, A.; Malfliet, Annelies; Seetharaman, Seshadri; Sietsma, J.; Yang, Y.

    2017-01-01

    In the present research on rare earth extraction from rare earth oxides (REOs), conversion of rare earth oxides into rare earth fluorides with fluoride fluxes is investigated in order to overcome the problem of low solubility of the rare earth oxides in molten fluoride salts as well as the formation

  15. CmRBP50 protein phosphorylation is essential for assembly of a stable phloem-mobile high-affinity ribonucleoprotein complex.

    Science.gov (United States)

    Li, Pingfang; Ham, Byung-Kook; Lucas, William J

    2011-07-01

    RNA-binding proteins (RBPs) form ribonucleoprotein (RNP) complexes that play crucial roles in RNA processing for gene regulation. The angiosperm sieve tube system contains a unique population of transcripts, some of which function as long-distance signaling agents involved in regulating organ development. These phloem-mobile mRNAs are translocated as RNP complexes. One such complex is based on a phloem RBP named Cucurbita maxima RNA-binding protein 50 (CmRBP50), a member of the polypyrimidine track binding protein family. The core of this RNP complex contains six additional phloem proteins. Here, requirements for assembly of this CmRBP50 RNP complex are reported. Phosphorylation sites on CmRBP50 were mapped, and then coimmunoprecipitation and protein overlay studies established that the phosphoserine residues, located at the C terminus of CmRBP50, are critical for RNP complex assembly. In vitro pull-down experiments revealed that three phloem proteins, C. maxima phloem protein 16, C. maxima GTP-binding protein, and C. maxima phosphoinositide-specific phospholipase-like protein, bind directly with CmRBP50. This interaction required CmRBP50 phosphorylation. Gel mobility-shift assays demonstrated that assembly of the CmRBP50-based protein complex results in a system having enhanced binding affinity for phloem-mobile mRNAs carrying polypyrimidine track binding motifs. This property would be essential for effective long-distance translocation of bound mRNA to the target tissues.

  16. Fluoride substitution in the Mn cluster from Photosystem II: EPR and X-ray absorption spectroscopy studies

    Science.gov (United States)

    DeRose, Victoria J.; Latimer, Matthew J.; Zimmermann, Jean-Luc; Mukerji, Ishita; Yachandra, Vittal K.; Sauer, Kenneth; Klein, Melvin P.

    1995-05-01

    X-band electron paramagnetic resonance (EPR) and Mn K-edge X-ray fluorescence absorption were used to study the effects of fluoride inhibition on the Mn complex in Photosystem II. The tetrameric Mn complex, responsible for the light-induced oxidation of H 2O to form molecular oxygen, is influenced by treatments in which the naturally occurring chloride salts are removed or replaced. Inhibition of the complex by fluoride is examined by parallel enzyme activity and EPR studies. It is found that, as a function of increasing fluoride concentration, the declining enzymatic activity is paralleled initially by an exchange of the S = 1/2 'multiline' EPR signal for the S > 1/2, 'g = 4' EPR signal in illuminated samples. High concentrations of fluoride induce a broad (≈ 200 G), featureless radical signal in samples which have not been illuminated; subsequent illumination of these samples also generates the g = 4 EPR signal. X-ray absorption studies (XAS) of fluoride-inhibited samples show subtle alterations of the conformation of the Mn complex that are consistent with the presence of two dissimilar pairs of Mn atoms. The halide studies are discussed in terms of structural models for the Mn complex.

  17. The kinetics of fluoride sorption by zeolite: Effects of cadmium, barium and manganese.

    Science.gov (United States)

    Cai, Qianqian; Turner, Brett D; Sheng, Daichao; Sloan, Scott

    2015-01-01

    Industrial wastewaters often consist of a complex chemical cocktail with treatment of target contaminants complicated by adverse chemical reactions. The impact of metal ions (Cd(2+), Ba(2+) and Mn(2+)) on the kinetics of fluoride removal from solution by natural zeolite was investigated. In order to better understand the kinetics, the pseudo-second order (PSO), Hill (Hill 4 and Hill 5) and intra-particle diffusion (IPD) models were applied. Model fitting was compared using the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). The Hill models (Hill 4 and Hill 5) were found to be superior in describing the fluoride removal processes due to the sigmoidal nature of the kinetics. Results indicate that the presence of Mn (100 mg L(-1)) and Cd (100 mg L(-1)) respectively increases the rate of fluoride sorption by a factor of ~28.3 and ~10.9, the maximum sorption capacity is increased by ~2.2 and ~1.7. The presence of Ba (100 mg L(-1)) initially inhibited fluoride removal and very poor fits were obtained for all models. Fitting was best described with a biphasic sigmoidal model with the degree of inhibition decreasing with increasing temperature suggesting that at least two processes are involved with fluoride sorption onto natural zeolite in the presence of Ba. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  18. Fluoride release and cariostatic potential of orthodontic adhesives with and without daily fluoride rinsing

    NARCIS (Netherlands)

    Chin, Yeen; Sandham, John; Rumachik, Elena N.; Ruben, Jan L.; Huysmans, Marie-Charlotte D. N. J. M.

    2009-01-01

    Introduction: In this study, we aimed to evaluate the fluoride-release profiles and caries lesion development in an enamel model with brackets cemented with 4 orthodontic adhesives with and without daily fluoride exposure. Methods: Four orthodontic adhesives (Ketac Cem mu, 3M ESPE, Seefeld, Germany;

  19. Effect of titanium tetrafluoride, amine fluoride and fluoride varnish on enamel erosion in vitro

    NARCIS (Netherlands)

    Vieira, A; Ruben, JL; Huysmans, MCDNJM

    2005-01-01

    This study aimed at evaluating the effect of 1 and 4% titanium tetrafluoride (TiF4) gels, amine fluoride (AmF) 1 and 0.25% and a fluoride varnish (FP) on the prevention of dental erosion. Two experimental groups served as controls, one with no pretreatment and another one pre-treated with a

  20. Fluoride release, recharge and flexural properties of polymethylmethacrylate containing fluoridated glass fillers.

    Science.gov (United States)

    Al-Bakri, I A; Swain, M V; Naoum, S J; Al-Omari, W M; Martin, E; Ellakwa, A

    2014-06-01

    The purpose of this study was to investigate the effect of fluoridated glass fillers on fluoride release, recharge and the flexural properties of modified polymethylmethacrylate (PMMA). Specimens of PMMA denture base material with various loading of fluoridated glass fillers (0%, 1%, 2.5%, 5% and 10% by weight) were prepared. Flexural properties were evaluated on rectangular specimens (n = 10) aged in deionized water after 24 hours, 1 and 3 months. Disc specimens (n = 10) were aged for 43 days in deionized water and lactic acid (pH 4.0) and fluoride release was measured at numerous intervals. After ageing, specimens were recharged and fluoride re-release was recorded at 1, 3 and 7 days after recharge. Samples containing 2.5%, 5% and 10% glass fillers showed significantly (p glass fillers specimens. All experimental specimens exhibited fluoride release in both media. The flexural strength of specimens decreased in proportion to the percentage filler inclusion with the modulus of elasticity values remaining within ISO Standard 1567. The modified PMMA with fluoridated glass fillers has the ability to release and re-release fluoride ion. Flexural strength decreased as glass filler uploading increased. © 2014 Australian Dental Association.

  1. Fluoride release and recharge abilities of contemporary fluoride-containing restorative materials and dental adhesives.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Koliniotou-Koumpia, Eugenia; Helvatzoglou-Antoniades, Maria; Kotsanos, Nikolaos

    2013-01-01

    The aim of this study was to evaluate the fluoride release of five fluoride-releasing restorative materials and three dental adhesives, before and after NaF solution treatment. Five restorative materials (Fuji IX GP, GC Corp.; Ketac N100, 3M ESPE; Dyract Extra, Dentsply; Beautifil II, Shofu Inc.; Wave, SDI) and three dental adhesives (Stae, SDI; Fluorobond II - Shofu Inc.; Prime & Bond NT, Dentsply) were investigated before and after NaF solution treatment. A fluoride ion-selective electrode was to measure fluoride concentrations. During the 86-day period before NaF solution treatment, Fuji IX GP released the highest amount of fluoride among the restorative materials while Prime & Bond NT was the highest among the dental adhesives. After NaF solution treatment, Fuji IX GP again ranked the highest in fluoride release among the restorative materials while Fluorobond II ranked the highest among dental adhesives. It was concluded that the compositions and setting mechanisms of fluoride-containing dental materials influenced their fluoride release and recharge abilities.

  2. Plaque formation and lactic acid production after use of amine fluoride/stannous fluoride mouthrinse

    NARCIS (Netherlands)

    Gerardu, V.A.M.; Buijs, M.; Loveren, C. van; Cate, J.M. ten

    2007-01-01

    The aim of this study was lo determine the effects of 3 wk of daily rinsing with amine fluoride/stannous fluoride (AmF/SnF2) mouthrinse on plaque formation at buccal and interproximal sites, and on the acid production in plaque. in a randomized clinical trial with 30 participants. The amount of

  3. Effects of a stannous fluoride-impregnated dental floss on in vivo salivary fluoride levels.

    Science.gov (United States)

    Flatt, Casey C; Warren-Morris, Donna; Turner, Steward D; Chan, Jarvis T

    2008-01-01

    The aim of this in vivo pilot study was to determine the concentration of fluoride retained intra-orally in saliva after flossing with dental floss impregnated with stannous fluoride (SnF(2)). Participants flossed their teeth ad libitum with 2 premeasured lengths of fluoridated dental floss. Expectorated saliva samples were collected in vials before flossing (PF), immediately postflossing(IPF), at 30 minutes (30), and 1 hour (60) after flossing for analysis with a fluoride-specific electrode and an Orion millivoltmeter. Postflossing samples were compared to the preflossing samples using ANOVA and Tukey's HSD. Differences between the PF and IPF group means were found to be statistically significant at pflossing (PF). It can be concluded that fluoride can be released from flossing with the tested SnF(2)-impregnated dental floss elevating salivary fluoride levels for at least 30 minutes. Use of this fluoride-containing dental floss offers an option for delivery of fluoride to individuals at risk for dental caries.

  4. Fluoride concentration in urine after silver diamine fluoride application on tooth enamel

    Science.gov (United States)

    Sari, D. L.; Bahar, A.; Gunawan, H. A.; Adiatman, M.; Rahardjo, A.; Maharani, D. A.; Toptanci, I. R.; Yavuz, I.

    2017-08-01

    Silver Diammine Fluoride (SDF), which contains fluoride, is known to inhibit tooth enamel demineralization and increase fluoride concentrations in saliva and urine. The aim of this study is to analyze the fluoride concentration in urine after application of SDF on tooth enamel. Urine from four subjects was collected prior to, 30 minutes after, and two and three hours after the application of SDF, and an ion-selective electrode was used to measure the fluoride concentrations. There was no significant difference between time 1 and time 2, time 1 and time 3, time 1 and time 4, time 2 and 3 (p > 0.05), and there was a significant difference between time 2 and time 4 as well as time 3 and time 4 (p SDF.

  5. Influence of the method of fluoride administration on toxicity and fluoride concentrations in Japanese quail

    Science.gov (United States)

    Fleming, W.J.; Schuler, C.A.

    1988-01-01

    Young Japanese quail (Coturnix japonica) were administered NaF for 16 d either in their diet or by esophageal intubation. Based on the total fluoride ion (Emg F-) intake over the l6-d experimental period, fluoride administered by intubation was at least six times more toxic than that fed in the diet. Dietary concentrations of 1,000 ppm F- (Emg F- for 16 d = approx. 144) produced no mortality, whereas intubated doses produced 73% or greater mortality in all groups administered 54 mg F- /kg/d or more (Emg F- for 16 d _ approx. 23 mg). GraphIc companson of the regression of log F- ppm in femurs/mg F- intake showed that fluoride levels in the femurs of quail administered fluoride by intubation were higher than in those administered fluoride in the diet.

  6. Hydrogen fluoride saccharification of wood: lignin fluoride content, isolation of alpha-D-glucopyranosyl fluoride and posthydrolysis of reversion products.

    Science.gov (United States)

    Hardt, H; Lamport, D T

    1982-04-01

    Wood chips from bigtooth aspen (Populus grandidentata Michx.) were saccharified by reaction with liquid hydrogen fluoride either anhydrous or containing up to 10% v/v water. The reaction products were separated into a solid lignin fraction and a water-soluble saccharide fraction. The fluoride content of the lignin (determined after alkaline fusion) was initially about 1 mg/g wood, but was lowered to 0.1 mg/g wood by grinding and washing. Thus little or no chemical binding of fluoride to lignin occurred during hydrogen fluoride (HF) solvolysis. Analysis of the water-soluble fraction by gel filtration on Biogel P2 columns showed a range of low-molecular-weight oligosaccharides and only 10-20% sugar monomers. Thus considerable reversion occurred during HF evacuation. Posthydrolysis conditions were optimized for these reversion products by varying temperature and acid concentration. Optimal conditions at 1 h were 140 degrees C with 100mN sulfuric acid or 225mN Hydrofluoric acid resulting in monomer yields of > 90% for 0.5% sugar solutions and > 80% for 10% sugar solutions. After reaction of pure cellulose (Filter paper) with hydrogen fluoride in the absence of water, and terminating the reaction with calcium carbonate, the reaction intermediate alpha-D-glucopyranosylfluoride was isolated with a maximal yield of 0.2 g/g paper. Upon purification via paper chromatography glucosylfluoride was identified by its specific rotation and also by gas chromatography-mass spectrometry of its tetra-O-trimethylsilyl derivative.

  7. ESR investigation of radicals formed in γ-irradiated vinylidene fluoride based copolymer: P(VDF-co-HFP)

    International Nuclear Information System (INIS)

    Dumas, Ludovic; Albela, Belén; Bonneviot, Laurent; Portinha, Daniel; Fleury, Etienne

    2013-01-01

    Samples of copolymer based on vinylidene fluoride and hexafluoropropene P(VDF-co-HFP) were exposed to γ-radiation performed under an inert atmosphere and the total amount of radicals was quantified by electron spin resonance spectroscopy (ESR). An in-depth study of recorded ESR spectra allowed the identification of several types of radical species formed during radiolysis. Starting from an ESR simulation model established for irradiated PVDF, seven radical species have been identified in the case of P(VDF-co-HFP): five of them are related to the VDF units while the two others are derived from the HFP unit. The model used to simulate the complex superimposed ESR signals is presented. The proportions of each species are discussed and correlated to the amount of HFP units contained in the copolymer, and to the stability of each species depending on their local environment. Furthermore, the evolution of radical density with radiation dose and the decay resulting from annealing at a given temperature are presented. Corresponding spectral evolution shows the progressive predominance of most stable species. - Highlights: ► ESR signal of γ-irradiated P(vinylidene fluoride-co-hexafluoropropene) containing 6 wt% of hexafluoropropene is modeled. ► The formation of seven major radical species is proposed for the first time. ► Despite a low comonomer content, 43% of radicals are localized on hexafluoropropene. ► Effect of dose and annealing highlight radical stability. ► Radical stability is found to depend on both chemical environment and chain location

  8. Chronologic Trends in Studies on Fluoride Mechanisms of Action.

    Science.gov (United States)

    Oh, H J; Oh, H W; Lee, D W; Kim, C H; Ahn, J Y; Kim, Y; Shin, H B; Kim, C Y; Park, S H; Jeon, J G

    2017-11-01

    Fluoride has been widely used for the prevention of dental caries since the mid-20th century. The aim of this study was to investigate the chronologic trends in studies on fluoride mechanisms of action against dental caries during the years 1950 to 2015. To this aim, queries such as "fluoride," "fluoride and demineralization," "fluoride and remineralization," "fluoride and (plaque or biofilms)," and "fluoride and (bacteria or microbials)" were submitted to PubMed to collect research article information, including titles, abstracts, publication dates, author affiliations, and publication journals. The article information that PubMed produced was then collected by an automatic web crawler and examined through informetrics and linguistic analyses. We found that the number of articles concerned with fluoride mechanisms of action against dental caries was 6,903 and gradually increased over time during the years 1950 to 2015. They were published by 1,136 journals-most notably, Caries Research and Journal of Dental Research. Of the articles published, those related to bacteria/microbials had a higher percentage (44%) than those dealing with plaque/biofilms, demineralization, and remineralization. With regard to the geographic distribution of authors, Europe and North America accounted for 65% of the articles during the years 1987 to 2015, although the number of authors in Asia sharply increased in recent years. Among the fluoride compounds, NaF was mentioned more frequently than SnF 2 , Na 2 PO 3 F, amine fluoride, and acidulated phosphate fluoride during the years 1986 to 2015. Water fluoridation received the most attention among the various fluoride application methods (toothpastes, mouthwashes, fluoride varnishes, and fluoride gels) during the same period. These results, obtained from employing informetrics and linguistic analyses, suggest that in studies on fluoride mechanisms of action, 1) the unbalanced geographic distribution of articles and 2) the heavy

  9. The Effect of Fluoridated and Non Fluoridated Mouth Washes on Color Stability of Different Aesthetic Arch Wires At Different Time Intervals (An in Vitro Study

    Directory of Open Access Journals (Sweden)

    Lubna Maky Hussein

    2018-01-01

    Full Text Available Background:The color stability of aesthetic arch wires is an important factor in the success of an aesthetic orthodontic treatment, but the color of these arch wires tends to change with time.This study was performed to assess the effect of two types of mouth washes on the color  stability of different types of aesthetic arch wires at different time intervals. Materials and methods:Four brands of nickel titanium coated aesthetic arch wires were used: epoxy coated (Orthotechnology and G&H and Teflon coated (Dany and Hubit.Thirty six samples were prepared, each sample contains ten halves of the aesthetic arch wires. They were divided into three groups according to the immersion media (distilled water as a control media, Listerine with fluoride and Listerine without fluoride and immersed for 30 seconds twice daily according to manufacturer's instructions to measure color change after 1 week, 3 weeks and 6 weeks by using spectrophotometer VITA Easyshade Compact according to Commission Internationale de l’Eclairage L*a*b* color space system. Results:It was found that there were highly significant differences in color change values of aesthetic arch wires among all immersion media at different time intervals and color change value increases as the time of immersion increases.Additionally, Listerine with fluoride mouth wash caused higher color change values of aesthetic arch wires than Listerine without fluoride and Hubit aesthetic arch wires were the least color stable while Orthotechnology aesthetic arch wires were the most color stable. Conclusions: We can conclude that the daily use of Listerine mouth washes could affect on the color stability of aesthetic arch wires. Although all tested aesthetic arch wires revealed color changes at variable degrees but some of these changes were not  visible and the others were clinically acceptable while the remaining were clinically unacceptable.

  10. Stable interaction between the human proliferating cell nuclear antigen loader complex Ctf18-replication factor C (RFC) and DNA polymerase {epsilon} is mediated by the cohesion-specific subunits, Ctf18, Dcc1, and Ctf8.

    Science.gov (United States)

    Murakami, Takeshi; Takano, Ryuji; Takeo, Satoshi; Taniguchi, Rina; Ogawa, Kaori; Ohashi, Eiji; Tsurimoto, Toshiki

    2010-11-05

    One of the proliferating cell nuclear antigen loader complexes, Ctf18-replication factor C (RFC), is involved in sister chromatid cohesion. To examine its relationship with factors involved in DNA replication, we performed a proteomics analysis of Ctf18-interacting proteins. We found that Ctf18 interacts with a replicative DNA polymerase, DNA polymerase ε (pol ε). Co-immunoprecipitation with recombinant Ctf18-RFC and pol ε demonstrated that their binding is direct and mediated by two distinct interactions, one weak and one stable. Three subunits that are specifically required for cohesion in yeast, Ctf18, Dcc1, and Ctf8, formed a trimeric complex (18-1-8) and together enabled stable binding with pol ε. The C-terminal 23-amino acid stretch of Ctf18 was necessary for the trimeric association of 18-1-8 and was required for the stable interaction. The weak interaction was observed with alternative loader complexes including Ctf18-RFC(5), which lacks Dcc1 and Ctf8, suggesting that the common loader structures, including the RFC small subunits (RFC2-5), are responsible for the weak interaction. The two interaction modes, mediated through distinguishable structures of Ctf18-RFC, both occurred through the N-terminal half of pol ε, which includes the catalytic domain. The addition of Ctf18-RFC or Ctf18-RFC(5) to the DNA synthesis reaction caused partial inhibition and stimulation, respectively. Thus, Ctf18-RFC has multiple interactions with pol ε that promote polymorphic modulation of DNA synthesis. We propose that their interaction alters the DNA synthesis mode to enable the replication fork to cooperate with the establishment of cohesion.

  11. Stable Isotope (δ13C, δ15N, δ34S) Analysis and Satellite Telemetry Depict the Complexity of Gray Wolf (Canis lupus) Diets in Southwest Alaska

    Science.gov (United States)

    Stanek, A.; Watts, D. E.; Cohn, B. R.; Spencer, P.; Mangipane, B.; Welker, J. M.

    2010-12-01

    Throughout Alaska, gray wolves (Canis lupus) are a top predator of large ungulates. While they primarily rely on ungulates such as moose (Alces alces) and caribou (Rangifer tarandus) as food, they are opportunistic and use alternative resources. The variation and supplemental protein sources in wolf diet has not been studied extensively on live animals currently using the landscape. With large seasonal influxes of Pacific salmon (Oncorhynchus sp.) into Alaska, terrestrial carnivore use of marine species is of particular interest. Using stable isotope (δ13C, δ15N, δ34S) analysis of wolf guard hair and blood, this study aims to determine the proportion of marine derived nutrients (MDN) in the diet of wolf packs within and surrounding Lake Clark National Park and Preserve and Alaska Peninsula and Becharof National Wildlife Refuges in Southwest Alaska. Satellite telemetry from the animals sampled facilitates quantification of landscape use patterns in correspondence with isotopic traits. Wolf pack territories within and surrounding the Lake Clark region appear to vary in spatial extent and in availability of MDN, such as salmon. Initial analysis shows that two packs with smaller home ranges, centrally located around areas with greater salmon availability, have enriched δ15N values compared to packs that have larger home ranges not centralized around salmon spawning waters. This pattern of isotopic enrichment is found in red blood cells, blood serum and hair, representing diets over different time scales. The enrichment in both blood and hair indicates a sustained use of MDN over the previous six to nine months. In the Lake Clark region, simple mixing model estimates suggest that up to 30% of wolf pack diets may be from marine sources. In contrast, packs with larger home ranges and less access to salmon have stable isotope values representative of a terrestrial diet.

  12. Viscosity of Molten Alkaline-Earth Fluorides

    Science.gov (United States)

    Takeda, Osamu; Hoshino, Yosuke; Anbo, Yusuke; Yanagase, Kei-ichi; Aono, Masahiro; Sato, Yuzuru

    2015-04-01

    The viscosities of molten alkaline-earth fluorides were measured using the oscillating crucible method, which is especially suitable for measuring molten salts with low viscosity. The results showed a good Arrhenius linearity over a wide temperature range. The measured viscosities and activation energies increased in the following order: . Judging by the charge density, the viscosity of alkaline-earth fluorides should increase from molten to . However, the results indicate a different tendency, which may be explained by a Coulomb force that is very strong. The low viscosity of can be attributed to a decreased cohesive force, due to a partial loss of the Coulomb force caused by a higher charge density of the material. The viscosities were also compared to those of molten alkali fluorides and alkaline-earth chlorides. The viscosities of molten alkaline-earth fluorides were higher than those of molten alkali fluorides and alkaline-earth chlorides. The viscosity determined in this study was compared to literature values and showed a reasonable value in the relatively low-viscosity region.

  13. Emissions of fluorides from welding processes.

    Science.gov (United States)

    Szewczyńska, Małgorzata; Pągowska, Emilia; Pyrzyńska, Krystyna

    2015-11-01

    The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H. Vincent and D. Mark at the Institute of Occupational Medicine (IOM), personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-N-trimethylammonium bromide (CTAB) were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8μg/L and 24μg/L, respectively. The linear range of calibration was 0.01-10mg/L, which corresponds to 0.0001-0.1mg of fluorides per m(3) in collection of a 20L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20-1.82mg/m(3), while the inhalable fraction contained 0.23-1.96mg/m(3) of fluorides during an eight-hour working day in the welding room. Copyright © 2015. Published by Elsevier B.V.

  14. Thermodynamic data-base for metal fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

    2001-05-01

    This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project.

  15. Thermodynamic data-base for metal fluorides

    International Nuclear Information System (INIS)

    Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho and others

    2001-05-01

    This study is aimed at collecting useful data of thermodynamic properties of various metal fluorides. Many thermodynamic data for metal fluorides are needed for the effective development, but no report of data-base was published. Accordingly, the objective of this report is to rearrange systematically the existing thermodynamic data based on metal fluorides and is to use it as basic data for the development of pyrochemical process. The physicochemical properties of various metal fluorides and metals were collected from literature and such existing data base as HSC code, TAPP code, FACT code, JANAF table, NEA data-base, CRC handbook. As major contents of the thermodynamic data-base, the physicochemical properties such as formation energy, viscosity, density, vapor pressure, etc. were collected. Especially, some phase diagrams of eutectic molten fluorides are plotted and thermodynamic data of liquid metals are also compiled. In the future, the technical report is to be used as basic data for the development of the pyrochemical process which is being carried out as a long-term nuclear R and D project

  16. Influences of charcoal and bamboo charcoal amendment on soil-fluoride fractions and bioaccumulation of fluoride in tea plants.

    Science.gov (United States)

    Gao, Hongjian; Zhang, Zhengzhu; Wan, Xiaochun

    2012-10-01

    High levels of fluoride in tea plants pose a potential health risk to humans who drink tea. It has been demonstrated that tea plant fluoride is closely related to the available fluoride in soil. But approaches that could be used to regulate the availability of fluoride in soil have been rarely seen. This study aims to investigate how the addition of charcoal and bamboo charcoal affected soil fluoride availability and bioaccumulation of fluoride in tea plants. In a microcosm experiment, tea plants were grown in the tea garden soil mixed with different amounts of charcoal and bamboo charcoal [that is, 0.5, 1.0, 2.5, and 5.0 % (w/w)]. Soil-fluoride fractions and fluoride accumulated in tea plants were determined using the sequential extraction and ion selective electrode method. Obtained results showed that both charcoal and bamboo charcoal additions significantly enhanced the concentrations of Fe/Mn oxide-bound fluoride, but significantly reduced the concentrations of water-soluble and exchangeable fluoride (p Charcoal and bamboo charcoal additions also significantly decreased the amounts of fluoride in tea roots and tea leaves (p charcoal and bamboo charcoal had no impacts on the tea quality, as indexed by the concentrations of polysaccharides, polyphenols, amino acids, and caffeine in tea leaves. These results suggested that application of charcoal and bamboo charcoal may provide a useful method to reduce the availability of fluoride in soil and the subsequent fluoride uptake by tea plants.

  17. State and National Water Fluoridation System (Public Water Systems)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Water Fluoridation Reporting System (WFRS) has been developed to provide tools to assist states in managing fluoridation programs. WFRS is designed to track all...

  18. Major histocompatibility complex class I peptide presentation after Salmonella enterica serovar typhimurium infection assessed via stable isotope tagging of the B27-presented peptide repertoire

    NARCIS (Netherlands)

    Ringrose, Jeffrey H.; Meiring, Hugo D.; Speijer, Dave; Feltkamp, Theodorus E. W.; van Els, Cecile A. C. M.; de Jong, Ad P. J. M.; Dankert, Jacob

    2004-01-01

    Reactive arthritis (ReA) induced by infection with several gram-negative bacteria is strongly associated with expression of the major histocompatibility complex class I molecule HLA-B27. It is thought that due to the intracellular lifestyle of ReA-inducing bacteria, bacterial fragments can be

  19. Pharmacokinetics of Fluoride in Toddlers After Application of 5% Sodium Fluoride Dental Varnish

    Science.gov (United States)

    Taves, Donald M.; Kim, Amy S.; Watson, Gene E.; Horst, Jeremy A.

    2014-01-01

    The prevalence of dental caries (tooth decay) among preschool children is increasing, driven partially by an earlier age of onset of carious lesions. The American Academy of Pediatrics recommends application of 5% sodium fluoride varnish at intervals increasing with caries risk status, as soon as teeth are present. However, the varnishes are marketed for treatment of tooth sensitivity and are regulated as medical devices rather than approved by the US Food and Drug Administration for prevention of dental caries (tooth decay). The objective of this research is to examine the safety of use in toddlers by characterizing the absorption and distribution profile of a currently marketed fluoride varnish. We measured urinary fluoride for 5 hours after application of fluoride varnish to teeth in 6 toddlers aged 12 to 15 months. Baseline levels were measured on a separate day. The urine was extracted from disposable diapers, measured by rapid diffusion, and extrapolated to plasma levels. The mean estimated plasma fluoride concentration was 13 μg/L (SD, 9 μg/L) during the baseline visit and 21 μg/L (SD, 8 μg/L) during the 5 hours after treatment. Mean estimated peak plasma fluoride after treatment was 57 μg/L (SD, 22 μg/L), and 20 μg/kg (SD, 4 μg/L) was retained on average. Retained fluoride was 253 times lower than the acute toxic dose of 5 mg/kg. Mean plasma fluoride after placement of varnish was within an SD of control levels. Occasional application of fluoride varnish following American Academy of Pediatrics guidance is safe for toddlers. PMID:25136045

  20. HOUSEHOLD PURIFICATION OF FLUORIDE CONTAMINATED MAGADI (TRONA)

    DEFF Research Database (Denmark)

    Nielsen, Joan Maj; Dahi, Elian

    1997-01-01

    Purification of fluoride contaminated magadi is studied using bone char sorption and calcium precipitation. The bone char treatment is found to be workable both in columns and in batches where the magadi is dissolved in water prior to treatment. The concentrations in the solutions were 89 g magadi....../L and 95 and 400 mg F/L respectively in natural and synthetic solutions. The fluoride removal capacities observed were 4.6 mg F/g bone char for the column system and 2.7 mg F/g bone char for the batch system in case of synthetic magadi solution. It is however concluded that the batch system is the best...... treatment method. A procedure for purification of fluoride contaminated magadi at household level is described....

  1. Preparation of uranium ingots from double fluorides

    International Nuclear Information System (INIS)

    Le Boulbin, E.

    1967-05-01

    A simple method has been developed for the preparation of uranium double fluorides and has given a new impetus to the study of the reduction of these compounds with a view to obtaining very pure uranium ingots. This reduction can be carried out using calcium or magnesium as the reducing agent, this latter metal being very interesting from the practical point of view. A comparative study of the heat balances of the reduction processes for the double fluorides and for uranium tetrafluoride has shown that reduction of the double fluorides is possible. The exact experimental conditions for these reductions have been determined. Our study has shown in particular that the reduction of the double salt UF 4 , CaF 2 by magnesium leads to the production of small (20 to 500 g) samples of high-purity uranium with a yield of 99 per cent. (author) [fr

  2. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    Beitz, J.V.; Williams, C.W.

    1996-01-01

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO 4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO 2 F 2 . Studies on the effect of added LiNO 3 or Na 2 WO 4 ·2H 2 O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF 6 content of WF 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF 6

  3. Complex-based OCT angiography algorithm recovers microvascular information better than amplitude- or phase-based algorithms in phase-stable systems

    Science.gov (United States)

    Xu, Jingjiang; Song, Shaozhen; Li, Yuandong; Wang, Ruikang K.

    2018-01-01

    Optical coherence tomography angiography (OCTA) is increasingly becoming a popular inspection tool for biomedical imaging applications. By exploring the amplitude, phase and complex information available in OCT signals, numerous algorithms have been proposed that contrast functional vessel networks within microcirculatory tissue beds. However, it is not clear which algorithm delivers optimal imaging performance. Here, we investigate systematically how amplitude and phase information have an impact on the OCTA imaging performance, to establish the relationship of amplitude and phase stability with OCT signal-to-noise ratio (SNR), time interval and particle dynamics. With either repeated A-scan or repeated B-scan imaging protocols, the amplitude noise increases with the increase of OCT SNR; however, the phase noise does the opposite, i.e. it increases with the decrease of OCT SNR. Coupled with experimental measurements, we utilize a simple Monte Carlo (MC) model to simulate the performance of amplitude-, phase- and complex-based algorithms for OCTA imaging, the results of which suggest that complex-based algorithms deliver the best performance when the phase noise is  animal models and human retina to verify the findings from the MC model through assessing the OCTA performance metrics of vessel connectivity, image SNR and contrast-to-noise ratio. We show that for all the metrics assessed, the complex-based algorithm delivers better performance than either the amplitude- or phase-based algorithms for both the repeated A-scan and the B-scan imaging protocols, which agrees well with the conclusion drawn from the MC simulations.

  4. 3,4,3-LI(1,2-HOPO): In Vitro Formation of Highly Stable Lanthanide Complexes Translates into Efficacious In Vivo Europium Decorporation

    Energy Technology Data Exchange (ETDEWEB)

    Sturzbecher-Hoehne, Manuel; Ng Pak Leung, Clara; Daleo, Anthony; Kullgren, Birgitta; Prigent, Anne-Laure; Shuh, David K.; Raymond, Kenneth N.; Abergel, Rebecca J.

    2011-07-13

    The spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) was investigated for its ability to act as an antennae that sensitizes the emission of Sm{sup III}, Eu{sup III}, and Tb{sup III} in the Visible range (Φ{sub tot} = 0.2 - 7%) and the emission of Pr{sup III}, Nd{sup III}, Sm{sup III}, and Yb{sup III} in the Near Infra-Red range, with decay times varying from 1.78 μs to 805 μs at room temperature. The particular luminescence spectroscopic properties of these lanthanide complexes formed with 3,4,3-LI(1,2-HOPO) were used to characterize their respective solution thermodynamic stabilities as well as those of the corresponding La{sup III}, Gd{sup III}, Dy{sup III}, Ho{sup III}, Er{sup III}, Tm{sup III}, and Lu{sup III} complexes. The remarkably high affinity of 3,4,3-LI(1,2-HOPO) for lanthanide metal ions and the resulting high complex stabilities (pM values ranging from 17.2 for La{sup III} to 23.1 for Yb{sup III}) constitute a necessary but not sufficient criteria to consider this octadentate ligand an optimal candidate for in vivo metal decorporation. The in vivo lanthanide complex stability and decorporation capacity of the ligand were assessed, using the radioactive isotope {sup 152}Eu as a tracer in a rodent model, which provided a direct comparison with the in vitro thermodynamic results and demonstrated the great potential of 3,4,3-LI(1,2-HOPO) as a therapeutic metal chelating agent.

  5. Cancer incidence and mortality in workers exposed to fluoride

    DEFF Research Database (Denmark)

    Grandjean, P; Olsen, J H; Jensen, O M

    1992-01-01

    Although a recent bioassay showed increased frequency of bone cancer in rats with high oral intake of fluoride, the data are reported as equivocal evidence of carcinogenicity. In humans, occupational fluoride exposure may cause skeletal fluorosis, and our earlier follow-up of fluoride...

  6. Examination of Reviews-Outcomes of Community Water Fluoridation ...

    African Journals Online (AJOL)

    There is a relationship between the concentration of water fluoridation of quantity higher than 1 ppm and the incidence of dental fluorosis. It was also observed that there is no relationship between fluoridation and cancer or bone fracture, or any other effects. As fluoridation of water is of immense benefit to a community with ...

  7. Fluoride removal performance of phosphoric acid treated lime ...

    African Journals Online (AJOL)

    Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system operations. In the continuous column operations, fluoride removal performance was ...

  8. Fluoride removal performance of phosphoric acid treated lime ...

    African Journals Online (AJOL)

    2010-11-25

    Nov 25, 2010 ... Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system opera- tions. In the continuous column operations, fluoride removal ...

  9. Health effects of fluoride pollution caused by coal burning

    Energy Technology Data Exchange (ETDEWEB)

    Ando, M.; Tadano, M.; Yamamoto, S.; Tamura, K.; Chen, X. [Regional Environment Division, National Institute for Environmental Studies, Tsukuba, 305-0083 Ibaraki (Japan); Asanuma, S. [Japan Institute of Rural Medicine, Usuda, Nagano (Japan); Watanabe, T. [Saku Central Hospital, Usuda, Nagano (Japan); Kondo, T. [Matsumoto Dental College, Shiojiri, Nagano (Japan); Sakurai, S. [Otsuma Women' s University, Tama, Tokyo (Japan); Ji, R.; Liang, C.; Cao, S. [Institute of Environmental Health and Engineering, Beijing (China); Hong, Z. [Shanxi Maternity and Children' s Hospital, Taiyuan (China)

    2001-04-23

    Recently a huge amount of fluoride in coal has been released into indoor environments by the combustion of coal and fluoride pollution seems to be increasing in some rural areas in China. Combustion of coal and coal bricks is the primary source of gaseous and aerosol fluoride and these forms of fluoride can easily enter exposed food products and the human respiratory tract. Major human fluoride exposure was caused by consumption of fluoride contaminated food, such as corn, chilies and potatoes. For each diagnostic syndrome of dental fluorosis, a log-normal distribution was observed on the logarithm of urinary fluoride concentration in students in China. Urinary fluoride content was found to be a primary health indicator of the prevalence of dental fluorosis in the community. In the fluorosis areas, osteosclerosis in skeletal fluorosis patients was observed with a high prevalence. A biochemical marker of bone resorption, urinary deoxypyridinoline content was much higher in residents in China than in residents in Japan. It was suggested that bone resorption was stimulated to a greater extent in residents in China and fluoride may stimulate both bone resorption and bone formation. Renal function especially glomerular filtration rate was very sensitive to fluoride exposure. Inorganic phosphate concentrations in urine were significantly lower in the residents in fluorosis areas in China than in non-fluorosis area in China and Japan. Since airborne fluoride from the combustion of coal pollutes extensively both the living environment and food, it is necessary to reduce fluoride pollution caused by coal burning.

  10. Modelling the Effects of Competing Anions on Fluoride Removal by ...

    African Journals Online (AJOL)

    Fe2O3 nano particles supported on functionalized poly-acrylonitrile was prepared. PAN-oxime-nano Fe2O3 was characterized by XRD, FTIR andTEMand used for fluoride adsorption. The adsorption capacity increased with increasing initial fluoride concentration and reaction time. Fluoride-removal performance of ...

  11. [Salt fluoridation and dental caries: state of the question].

    Science.gov (United States)

    Vautey, Solveig; Ranivoharilanto, Eva; Decroix, Bernard; Tubert-Jeannin, Stéphanie

    2017-04-27

    Objective: Dental caries remains a public health problem, particularly among socially deprived populations. In some developing countries, salt fluoridation programmes have been recently developed, but the use of fluoridated salt is limited worldwide and the level of evidence for its efficacy remains debated. Method: A literature review was conducted to identify epidemiological or clinical studies that have evaluated the effect of salt fluoridation on dental caries experiences in children. Results: After a literature search, 22 references were selected reporting data on the preventive effect of salt fluoridation programmes in Europe (Hungary, Switzerland, France, Germany) and South and Central America (Colombia, Mexico, Jamaica...). Data were mainly obtained from descriptive or retrospective epidemiological studies. The results indicate that, in the absence of topical fluoride support, salt fluoridation leads to a significant reduction in caries indexes among treated children compared to a control group. In a context of widespread use of fluoridated toothpastes, the additional effect achieved by salt fluoridation is limited. The prevalence of fluorosis is not markedly increased with fluoridated salt, but side effects were not always evaluated. Conclusion: Today, a salt fluoridation programme could be useful in areas in which fluoridated toothpastes are not widely used. The communication policy promoting the consumption of fluoridated salt is crucial to ensure the effectiveness of such a programme.

  12. Fluoride levels in commercially available rice in Ethiopia | Tegegne ...

    African Journals Online (AJOL)

    Alkaline fusion was used for sample preparation of six varieties for both the raw rice and rice cooked with tap water and fluoridated water. Fluoride levels ranged from 0.1-5.5 mg/kg in raw rice sample. Rice which was cooked with different fluoride levels of water showed increment depending on the method of cooking.

  13. Fluoride removal studies in water using natural materials : technical ...

    African Journals Online (AJOL)

    ℓ-1 of fluoride was passed through the column and the variation of fluoride removal for a known rate of flow was studied. Correlation analysis of defluoridation capacity with time was done and an attempt has been made to classify them accordingly. The study reveals that red soil has good fluoride removal capacity followed ...

  14. An inter-laboratory comparative study of fluoride determination in ...

    African Journals Online (AJOL)

    South Africa is on the brink of implementation of mandatory fluoridation of municipal water following the final approval by Parliament in 2001. The ability to accurately measure fluoride in water is an obvious prerequisite for the safe and effective implementation of water fluoridation. This paper evaluates the current status of ...

  15. The accuracy of fluoride measurement in water and its implications ...

    African Journals Online (AJOL)

    The accurate measurement of the fluoride concentration in water is an essential prerequisite to stay within the allowable dosing tolerances required by the South African water fluoridation legislation. In the absence of reliable error estimates for fluoride measurement in natural water samples, a study was conducted utilising ...

  16. Geographical mapping of fluoride levels in drinking water sources in ...

    African Journals Online (AJOL)

    Background: Knowledge of fluoride levels in drinking water is of importance in dental public health, yet this information is lacking, at national level, in Nigeria. Objective: To map out fluoride levels in drinking water sources in Nigeria. Materials and Methods: Fluoride levels in drinking water sources from 109 randomly ...

  17. Spatial analysis of fluoride concentrations in drinking water and ...

    African Journals Online (AJOL)

    Namibia, the driest country in sub-Saharan Africa, is largely reliant on groundwater for its potable water demand and groundwater is a major source of naturally-occurring fluoride. This study assessed the spatial distribution of fluoride in potable water and appraised the population at risk for high fluoride intake. Analysis of ...

  18. Fluoride removal from aqueous solution by pumice: case study on ...

    African Journals Online (AJOL)

    The fluoride removal from synthetic water by pumice was studied at batch experiments in this study. The effect of pH, contact time, fluoride concentration and adsorbent dose on the fluoride sequestration was investigated. The optimum conditions were studied on Kuhbonan water as a case study. The results showed that ...

  19. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyvinylidene fluoride resins. 177.2510 Section... as Components of Articles Intended for Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used as articles or components of articles intended for repeated use...

  20. Redox Activity of Oxo-Bridged Iridium Dimers in an N,O-Donor Environment: Characterization of Remarkably Stable Ir(IV,V) Complexes.

    Science.gov (United States)

    Sinha, Shashi Bhushan; Shopov, Dimitar Y; Sharninghausen, Liam S; Stein, Christopher J; Mercado, Brandon Q; Balcells, David; Pedersen, Thomas Bondo; Reiher, Markus; Brudvig, Gary W; Crabtree, Robert H

    2017-07-19

    Chemical and electrochemical oxidation or reduction of our recently reported Ir(IV,IV) mono-μ-oxo dimers results in the formation of fully characterized Ir(IV,V) and Ir(III,III) complexes. The Ir(IV,V) dimers are unprecedented and exhibit remarkable stability under ambient conditions. This stability and modest reduction potential of 0.99 V vs NHE is in part attributed to complete charge delocalization across both Ir centers. Trends in crystallographic bond lengths and angles shed light on the structural changes accompanying oxidation and reduction. The similarity of these mono-μ-oxo dimers to our Ir "blue solution" water-oxidation catalyst gives insight into potential reactive intermediates of this structurally elusive catalyst. Additionally, a highly reactive material, proposed to be a Ir(V,V) μ-oxo species, is formed on electrochemical oxidation of the Ir(IV,V) complex in organic solvents at 1.9 V vs NHE. Spectroelectrochemistry shows reversible conversion between the Ir(IV,V) and proposed Ir(V,V) species without any degradation, highlighting the exceptional oxidation resistance of the 2-(2-pyridinyl)-2-propanolate (pyalk) ligand and robustness of these dimers. The Ir(III,III), Ir(IV,IV) and Ir(IV,V) redox states have been computationally studied both with DFT and multiconfigurational calculations. The calculations support the stability of these complexes and provide further insight into their electronic structures.

  1. Prospecting for safe (low fluoride groundwater in the Eastern African Rift: the Arumeru District (Northern Tanzania

    Directory of Open Access Journals (Sweden)

    G. Ghiglieri

    2010-06-01

    Full Text Available A multidisciplinary research effort, including geological, hydrogeological, hydro-chemical, geophysical and hydrological investigations, was aimed at locating a source of safe groundwater for a district of northern Tanzania, within the western branch of the East Africa Rift Valley, where water shortage is common and much of the surface water carries unacceptable levels of dissolved fluoride. The 440 km2 study area lies in the northern part of Arumeru district and is dominated by Mt. Meru (4565 m a.s.l.. The local climate is semi-arid, with distinct wet and dry seasons. Four hydrogeological complexes were identified, occurring within different volcanic formations, either alone or superimposed upon one another. The groundwater flow system was interpreted from the spatial distribution of the springs, combined with a lithology- and geometry-based reconstruction of the aquifers. The dominant pattern consists of a multi-directional flow from the higher elevations in the south towards the lower areas in the north, but this is complicated by structures such as grabens, faults, lava domes and tholoids. After the identification of the major fluoride source, an interference pattern between groundwater and high fluoride surface water was drawn. Finally, vertical electrical soundings were performed to define the location of aquifers in regions where release of fluoride was prevented. The methodological approach for the prospecting of safe water in a semi-arid, fluoride polluted region was validated by the drilling of a 60 m deep well capable of supplying at least 3.8 l/s of low fluoride, drinkable water.

  2. Graphite Fluoride Fiber Composites For Heat Sinking

    Science.gov (United States)

    Hung, Ching-Cheh; Long, Martin; Stahl, Mark

    1989-01-01

    Graphite fluoride fiber/polymer composite materials consist of graphite fluoride fibers in epoxy, polytetrafluoroethylene, or polyimide resin. Combines high electrical resistivity with high thermal conductivity and solves heat-transfer problems of many electrical systems. Commercially available in powder form, for use as dry lubricant or cathode material in lithium batteries. Produced by direct fluorination of graphite powder at temperature of 400 to 650 degree C. Applications include printed-circuit boards for high-density power electronics, insulators for magnetic-field cores like those found in alternators and transformers, substrates for thin-film resistors, and electrical-protection layers in aircraft de-icers.

  3. Fabrication of dense panels in lithium fluoride

    International Nuclear Information System (INIS)

    Farcy, P.; Roger, J.; Pointud, R.

    1958-04-01

    The authors report a study aimed at the fabrication of large and dense lithium fluoride panels. This sintered lithium fluoride is then supposed to be used for the construction of barriers of protection against a flow of thermal neutrons. They briefly present the raw material which is used under the form of chamotte obtained through a pre-sintering process which is also described. Grain size measurements and sample preparation are indicated. Shaping, drying, and thermal treatment are briefly described, and characteristics of the sintered product are indicated

  4. Giant flexoelectricity in polyvinylidene fluoride films

    Energy Technology Data Exchange (ETDEWEB)

    Baskaran, Sivapalan; Ramachandran, Narayanan; He Xiangtong; Thiruvannamalai, Sankar; Lee, Ho Joon; Heo, Hyun [Department of Mechanical and Aerospace Engineering, State University of New York, Buffalo, NY 14260 (United States); Chen Qin [GE Global Research Center, 1 Research Circle, Niskayuna, NY 12309 (United States); Fu, John Y., E-mail: youweifu@buffalo.ed [Department of Mechanical and Aerospace Engineering, State University of New York, Buffalo, NY 14260 (United States)

    2011-05-16

    Recent studies have shown that giant flexoelectricity may exist in certain elastomers with bent-core molecular structures, which contradicts the previous theoretical estimation that the flexoelectric coupling is small in those materials. In this Letter, we report an analogous phenomenon, i.e., the giant direct flexoelectric effect, observed in a polyvinylidene fluoride (PVDF) film. Our experimental studies indicate that such an enhanced flexoelectric effect might be induced by the interaction between the energy couplings of the apolar and the polar molecular structures of the polymer film under elastic deformation. - Highlights: Polyvinylidene fluoride (PVDF) film with not fully crystallized {alpha}- and {beta}-phases. Flexoelectric measurement. Giant direct flexoelectric effect in PVDF.

  5. Reconstructing temporal variation of fluoride uptake in eastern grey kangaroos (Macropus giganteus) from a high-fluoride area by analysis of fluoride distribution in dentine.

    Science.gov (United States)

    Kierdorf, Horst; Rhede, Dieter; Death, Clare; Hufschmid, Jasmin; Kierdorf, Uwe

    2016-04-01

    Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

    International Nuclear Information System (INIS)

    Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule; Rustin, Pierre

    2011-01-01

    Highlights: → NDUFB6 is required for activity of mitochondrial complex I in human cell lines. → Lentivirus based RNA interference results in frequent off target insertions. → Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

  7. The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule [Inserm U676, Hopital Robert Debre, F-75019 Paris (France); Universite Paris 7, Faculte de medecine Denis Diderot, IFR02 Paris (France); Rustin, Pierre, E-mail: pierre.rustin@inserm.fr [Inserm U676, Hopital Robert Debre, F-75019 Paris (France); Universite Paris 7, Faculte de medecine Denis Diderot, IFR02 Paris (France)

    2011-10-22

    Highlights: {yields} NDUFB6 is required for activity of mitochondrial complex I in human cell lines. {yields} Lentivirus based RNA interference results in frequent off target insertions. {yields} Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

  8. Effects of tannin-fluoride and milk-fluoride mixture on human enamel erosion from inappropriately chlorinated pool water.

    Science.gov (United States)

    Boonviriya, Sumalee; Tannukit, Sissada; Jitpukdeebodintra, Suwanna

    2017-01-01

    This in vitro study aimed to investigate the efficacy of tannin-fluoride and milk-fluoride mixtures on human enamel erosion after exposure to inappropriately chlorinated pool water. Enamel specimens were immersed in swimming pool water (pH 2.7) for 30 min and in each test reagent for 4 min once a day for 60 consecutive days (group I: control, group II: tannin-fluoride, group III: milk-fluoride, group IV: tannin-fluoride before and milk-fluoride after erosive challenge, and group V: milk containing tannin-fluoride before and after erosive exposure). Surface microhardness was assessed on days 0, 30, and 60. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were performed after treatment of samples for 60 days. Surface microhardness of experimental groups was ranked as follows: group III > group IV-group V > group II > group I (P erosive enamel surface after treatment with tannin-fluoride and milk-fluoride mixtures. Furthermore, EPMA profiles showed decrease of phosphorus and increase of fluoride content in groups II and IV. In conclusion, we demonstrated that treatment with fluoridated milk with or without tannin-fluoride has protective effects against enamel erosion caused by low-pH swimming pool water.

  9. Comparative evaluation of fluoride release from PRG-composites and compomer on application of topical fluoride: An in-vitro study

    Directory of Open Access Journals (Sweden)

    Dhull K

    2009-03-01

    Full Text Available Aims and Objective: To determine the fluoride release from Giomer and Compomer, using different topical fluoride regimes, and to compare the amount of fluoride release from giomer with that of compomer. Materials and Method: Forty-eight specimens of each giomer and compomer were divided into four treatment groups, namely, control group, fluoridated dentifrice (500 ppm once daily group, fluoridated dentifrice (500 ppm twice daily group, fluoridated dentifrice (500 ppm once daily + fluoridated mouthwash (225 ppm group. Each specimen was suspended in demineralizing solution for six hours and remineralizing solution for 18 hours. Fluoride release was measured in both the demineralizing solution and remineralizing solution daily for seven days. Total daily fluoride release for each specimen was calculated by adding the amount released in the demineralizing solution to that released in remineralizing solution. Results and Conclusion: The fluoride release (ppm was found to be more in Giomer when compared to Compomer. The fluoride released from Giomer and Compomer was significantly greater in the acidic demineralizing solution than in the neutral remineralizing solution. It was found that increasing fluoride exposure significantly increased fluoride release from the giomer and compomer. It was found that the fluoride release from the subgroups of giomer and compomer was in the following order: fluoridated dentifrice twice daily > fluoridated dentifrice once daily + fluoridated mouthwash > fluoridated dentifrice once daily > control group. It was found that the giomer showed a greater fluoride uptake than the compomer.

  10. Caries development after substitution of supervised fluoride rinses and toothbrushings by unsupervised use of fluoride toothpaste.

    Science.gov (United States)

    Karjalainen, S; Eriksson, A L; Ruokola, M; Toivonen, A

    1994-12-01

    In a nonfluoridated community of Finland, where fortnightly fluoride rinsing with 0.2% sodium fluoride has been used for nearly two decades, a total of 313 children 7-8 yr old were recruited and randomly divided into two groups. 206 children completed the 3-yr trial. The control group (n = 94) participated in the rinsing program which included supervised toothbrushings, while the test group (n = 112) received a new fluoride toothpaste tube (0.15% F) for home use every second month. Annual dental recordings, treatment plannings and the treatment itself were all carried out by one clinician. At the end of the study the number of caries-free children of the toothpaste group was lower (P toothpaste may not be a sufficient substitute for the school-based fortnightly fluoride rinses and supervised toothbrushings in caries prevention of children with erupting permanent teeth.

  11. Data on fluoride contents in groundwater of Bushehr province, Iran

    Directory of Open Access Journals (Sweden)

    Sina Dobaradaran

    2018-04-01

    Full Text Available In this article, we measured the levels of fluoride in groundwater. The samples were taken from groundwater in Bushehr's province, Iran. After the collection of samples, the concentration levels of fluoride were determined by the standard SPADNS method using spectrometer. The mean concentration levels of fluoride in water of all stations were higher than the WHO drinking water guideline. Microsoft Office Excel 2016 was used for calculation of mean values. The mean concentration level of fluoride instatement were in the range of 1.52 to 3.64 mg l-1. Keywords: Bushehr, Drinking water, Fluoride, Groundwater, Spectrometer

  12. Effect of fluoride ion on the stability of DNA hairpin

    Science.gov (United States)

    Liu, Chao; Zhai, Weili; Gong, Hongling; Liu, Yanhui; Chen, Hu

    2017-06-01

    Fluoride prevents tooth decay as an additive in oral hygiene products, while high dose intake of fluoride from contaminated drinking water leads to fluorosis. Here we studied the effect of fluoride ion on the stability of DNA double helix using magnetic tweezers. The equilibrium critical force decreases with increasing concentration of fluoride in the range from 1 mM to 100 mM. Our results give the first quantitative measurement of DNA stability in the presence of fluoride ion, which might disturb DNA-related biological processes to cause fluorosis.

  13. Heat Shock Protein member A2 forms a stable complex with angiotensin converting enzyme and protein disulfide isomerase A6 in human spermatozoa.

    Science.gov (United States)

    Bromfield, Elizabeth G; McLaughlin, Eileen A; Aitken, Robert John; Nixon, Brett

    2016-02-01

    Given the importance of the chaperone Heat Shock Protein A2 (HSPA2) in the regulation of male fertility, this study aimed to identify and characterize additional proteins that may rely on the activity of this chaperone in human spermatozoa. In view of the findings in this study we propose that angiotensin converting enzyme (ACE) and protein disulfide isomerase A6 (PDIA6) are novel interacting proteins of HSPA2 and that this multimeric complex may participate in key elements of the fertilization cascade. The molecular chaperone HSPA2 plays a pivotal role in the remodelling of the sperm surface during capacitation. Indeed, human spermatozoa that are deficient in HSPA2 protein expression lack the ability to recognize human oocytes, resulting in repeated IVF failure in a clinical setting. Moreover, our recent work has shown that defective HSPA2 function induced by oxidative stress leads to the aberrant surface expression of one of its interacting proteins, arylsulfatase A, and thus contributes to a loss of sperm-zona pellucida adhesion. Human spermatozoa were collected from fertile donors, capacitated and prepared for Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) analysis. Protein complexes resolved via BN-PAGE were excised and their constituents were identified using mass spectrometry. The interactions between ACE, PDIA6 and HSPA2 were then confirmed using immunoprecipitation and proximity ligation assays and the localization of these proteins was assessed in isolated spermatozoa and commercially available human testis tissue sections. Finally, pharmacological inhibition of ACE was performed to assess the role of ACE in human sperm capacitation. Herein we have identified ACE and PDIA6 as potential HSPA2-interacting proteins and shown that this assemblage resides in membrane raft microdomains located in the peri-acrosomal region of the sperm head. Additionally, the surface expression of PDIA6, but not ACE, was shown to be dynamically regulated during sperm

  14. Stable X chromosome inactivation involves the PRC1 Polycomb complex and requires histone MACROH2A1 and the CULLIN3/SPOP ubiquitin E3 ligase

    DEFF Research Database (Denmark)

    Hernández-Muñoz, Inmaculada; Lund, Anders H; van der Stoop, Petra

    2005-01-01

    protein BMI1 and the variant histone MACROH2A. We find that in addition to MACROH2A, PRC1 is recruited to the inactivated X chromosome in somatic cells in a highly dynamic, cell cycle-regulated manner. Importantly, RNAi-mediated knock-down of CULLIN3 or SPOP results in loss of MACROH2A1 from...... the inactivated X chromosome (Xi), leading to reactivation of the Xi in the presence of inhibitors of DNA methylation and histone deacetylation. Likewise, Xi reactivation is also seen on MacroH2A1 RNAi under these conditions. Hence, we propose that the PRC1 complex is involved in the maintenance of X chromosome...

  15. Enhanced sorption and photodegradation of chlorophenol over fluoride-loaded TiO2.

    Science.gov (United States)

    Cong, Shan; Xu, Yiming

    2011-08-30

    The presence of NaF in the aqueous suspension of TiO(2) can accelerate the photocatalytic degradation of organic pollutants. However, disposal of such a fluoride-containing wastewater is not allowed by environmental regulation. In the present work, we report on surface modification of TiO(2) with a hardly water soluble salt, fluorite and fluorapatite. The modified catalysts at low loading displayed a higher activity than bare TiO(2) for the sorption and photocatalytic degradation of phenol and 2,4-dichlorophenol in water. A kinetic study using butanol as hydroxyl radical scavenger revealed that the fluoride-modified catalysts produced more hydroxyl radicals than bare TiO(2). Five repeated experiments showed that the fluorapatite-modified TiO(2) was very stable, and could be re-used without significant loss in activity. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey

    OpenAIRE

    D J Veeresh; Umesh Wadgave

    2014-01-01

    Introduction: The major reason for decline in dental caries across globe is because of widespread use of fluoride dentifrices. For a fluoride dentifrice to be effective in the control of dental caries, an adequate concentration of the fluoride must be soluble. Objective: To assess soluble fluoride and total fluoride content in selected commercial dentifrices in Davangere. Materials and Methods: The soluble fluoride and total fluoride content in six selected commercial dentifrices in Davangere...

  17. Estimated Fluoride Doses from Toothpastes Should be Based on Total Soluble Fluoride

    Directory of Open Access Journals (Sweden)

    Jaime A. Cury

    2013-11-01

    Full Text Available The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF rather than levels of bioavailable fluoride (total soluble fluoride—TSF in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80 or children’s toothpaste (n = 78. The estimated dose (mg F/day/Kg of body weight of TF or TSF ingested was calculated from the chemical analysis of the toothpastes. Although the ingested dose of TF from the family toothpastes was higher than that from the children’s toothpastes (0.074 ± 0.007 and 0.039 ± 0.003 mg F/day/Kg, respectively; p 0.05. The fluoride dose ingested by children from toothpastes may be overestimated if based on the TF of the product. This finding suggests that the ingested dose should be calculated based on TSF. Dose of TSF ingested by children is similar whether family or children’s toothpaste is used.

  18. The effect of fluoride application on fluoride release and the antibacterial action of glass ionomers.

    Science.gov (United States)

    Seppä, L; Forss, H; Ogaard, B

    1993-09-01

    The aim of this study was to investigate whether the release of fluoride and the antimicrobial effect of freshly mixed glass ionomers could be prolonged by application of fluoride on aged material. Test slabs of freshly mixed and aged (14 d in water) conventional and silver glass ionomer (Ketac-Fil and Ketac-Silver, Espe, Seefeld, Germany) and composite (Silux Plus, 3M, St. Paul, MN) were fitted into the bottom of a test tube. A layer of S. mutans Ingbritt cells was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% sucrose solution. After the incubation, pH, F, and Ca contents of the fluid phase, and F, Mg, P, and K contents of the cells were determined. The aged glass-ionomer samples were then covered with toothpaste (0.1% F) or with fluoride gel (1.25% F), and the composite samples with fluoride gel. After being thoroughly rinsed, S. mutans cells were incubated on the samples as above. The pH fall was significantly inhibited by freshly mixed glass ionomers, and there were changes in cellular cation and phosphorus contents. Large amounts of fluoride were found in the fluid and cells. For old glass ionomers, no inhibitory effect on pH fall could be seen. Fluoride release had decreased to a low level.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Fluoride varnish or fluoride mouth rinse? A comparative study of two school-based programs.

    Science.gov (United States)

    Keller, M K; Klausen, B J; Twetman, S

    2016-03-01

    In many Danish communities, school-based fluoride programs are offered to children with high caries risk in adjunct to tooth brushing. The purpose of this field trial was to compare the caries-preventive effectiveness of two different fluoride programs in 6-12 year olds. Clinical controlled trial. The 2-year study was conducted in Public Dental Clinics in a multicultural low-socioeconomic suburban area of Odense, Denmark with an elevated prevalence of caries compared to the city average. 1,018 children (aged 6-12 years) from 9 different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. One group received a semi-annual fluoride varnish applications (FV) and the other group continued with an existing program with fluoride mouth rinses once per week (FMR). All children received oral hygiene instructions and comprehensive dental care at the local Public Dental Clinics throughout the study period. Increment of caries lesions in permanent teeth at both cavitated and initial caries levels. The groups were balanced at baseline. After two years, 961 children (94.4%) were reexamined. The FV group showed a mean DMFS increment of 0.36 compared to 0.41 in the FMR group. The corresponding values for initial caries lesions were 0.83 and 0.91 respectively. There were no statistically significant differences in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program.

  20. Estimated Fluoride Doses from Toothpastes Should be Based on Total Soluble Fluoride

    Science.gov (United States)

    Oliveira, Maria José L.; Martins, Carolina C.; Paiva, Saul M.; Tenuta, Livia M. A.; Cury, Jaime A.

    2013-01-01

    The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF) rather than levels of bioavailable fluoride (total soluble fluoride—TSF) in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80) or children’s toothpaste (n = 78)). The estimated dose (mg F/day/Kg of body weight) of TF or TSF ingested was calculated from the chemical analysis of the toothpastes. Although the ingested dose of TF from the family toothpastes was higher than that from the children’s toothpastes (0.074 ± 0.007 and 0.039 ± 0.003 mg F/day/Kg, respectively; p 0.05). The fluoride dose ingested by children from toothpastes may be overestimated if based on the TF of the product. This finding suggests that the ingested dose should be calculated based on TSF. Dose of TSF ingested by children is similar whether family or children’s toothpaste is used. PMID:24189183

  1. Diffusion of fluoride in bovine enamel

    International Nuclear Information System (INIS)

    Flim, G.J.; Arends, J.; Kolar, Z.

    1976-01-01

    The uptake of 18 F and the penetration of both F and 18 F in bovine enamel was investigated. Sodium fluoride solutions buffered at pH 7 were employed. The uptake of 18 F was measured by a method described by R. Duckworth and M. Braden, Archs. Oral. Biol., 12(1967), pp. 217-230. The penetration concentration profiles of fluoride (F, 18 F) in the enamel were measured by a sectioning technique. The 18 F uptake in enamel was proportional to approximately tsup(3/4); t being the uptake time. The 18 F concentration as a function of the position in the enamel can be described by: c*(x,t) = c 0 *(t)exp[-α*(t)x]. After correction for the initial fluoride concentration in enamel, for unlabelled fluoride the same dependency is obtained. A model based on simultaneous diffusion and chemical reaction in the pores and diffusion into the hydroxyapatite crystallites will be presented. The results show that diffusion coefficients of the pores are approximately equal to 10 -10 cm 2 s -1 and in the apatite crystallites approximately equal to 10 -17 cm 2 s -1 . The limitations and the approximations of the model are discussed

  2. Geochemical assessment of fluoride enrichment and nitrate ...

    Indian Academy of Sciences (India)

    62

    minerals. By reducing the consumption of fertilizer and stress over groundwater, the water quality can be improved. Key Word- Hydro-geochemistry, Fluoride, ... source (industries effluent, fertilizer industry and fertilizer used in agriculture field) influences ...... groundwater of the Taiyuan basin, Northern China; J. Geochem.

  3. Unconventional fluoride conversion coating preparation and characterization

    Czech Academy of Sciences Publication Activity Database

    Drábiková, J.; Fintová, Stanislava; Tkacz, J.; Doležal, P.; Wasserbauer, J.

    2017-01-01

    Roč. 64, č. 6 (2017), s. 613-619 ISSN 0003-5599 Institutional support: RVO:68081723 Keywords : fluoride conversion coating * magnesium * corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 0.364, year: 2016 http://www.emeraldinsight.com/doi/abs/10.1108/ACMM-02-2017-1757

  4. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    Science.gov (United States)

    Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Arcangeli, Giulio

    2016-01-01

    Hydrogen fluoride (HF) is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC)/mass spectrometry (MS). After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90). In addition, precision (relative standard deviation for n = 10, 4.3%), sensitivity (0.2 μg/filter), and linearity (2.0–4000 μg/filter; correlation coefficient: 0.9913) were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day) and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation. PMID:27829835

  5. FLUORIDE REDUCTION FROM WATER BY PRECIPITATION WITH ...

    African Journals Online (AJOL)

    2013-12-31

    Dec 31, 2013 ... standards, which indicated that the consumption of high fluoride water for long periods causes health complications ... has been done with different salts of calcium and determination of optimal conditions of ... temperature T were measured, after that different amount of the same salt was added to each cup .

  6. Fluoride treatment in corticosteroid induced osteoporosis.

    OpenAIRE

    Rejou, F; Dumas, R; Belon, C; Meunier, P J; Edouard, C

    1986-01-01

    Severe osteoporosis with multiple vertebral fractures occurred in two girls receiving prolonged high dose corticosteroids for relapsing dermatomyositis. Sodium fluoride, supplemented with calcium and vitamin D, helped control secondary osteoporosis in one case and should be considered as part of the curative treatment of corticoid induced osteoporosis.

  7. CORRELATION AMONG FLUORIDE AND METALS IN IRRIGATION ...

    African Journals Online (AJOL)

    Preferred Customer

    The levels of fluoride and selected metals in Ethiopian Rift Valley soils and irrigation water in the nearby sources were ... exhaust fumes, process waters and waste from various industrial processes [1]. The uses of ... into four sub-systems: Lake Rudolf, Chew Bahir, the Main Ethiopian Rift (MER) and the Afar. The seismically ...

  8. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride.

    Science.gov (United States)

    Dugheri, Stefano; Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Mucci, Nicola; Arcangeli, Giulio

    2016-01-01

    Hydrogen fluoride (HF) is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC)/mass spectrometry (MS). After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90). In addition, precision (relative standard deviation for n = 10, 4.3%), sensitivity (0.2  μ g/filter), and linearity (2.0-4000  μ g/filter; correlation coefficient: 0.9913) were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day) and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation.

  9. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    Directory of Open Access Journals (Sweden)

    Stefano Dugheri

    2016-01-01

    Full Text Available Hydrogen fluoride (HF is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC/mass spectrometry (MS. After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90. In addition, precision (relative standard deviation for n=10, 4.3%, sensitivity (0.2 μg/filter, and linearity (2.0–4000 μg/filter; correlation coefficient: 0.9913 were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation.

  10. Fluoride in dental biofilm and saliva

    DEFF Research Database (Denmark)

    Larsen, Line Staun

    mellem fluoridkoncentrationerne i biofilmsediment og fordeling af caries mellem regioner. Forskere anbefales at være opmærksomme på de intra-orale forskelle i fluoridkoncentrationer mellem regioner samt sikre balancering af effekten af region, når der indsamles dental biofilm til fluoridanalyse. I det...... biofilmsediment. Dette indikerer at brugen af 5.000 ppm fluorid tandpasta kan føre til forbedret carieskontrol. Det var påfaldende, at en næsten tre en halv ganges forøgelse af fluorideksponeringen kun førte til en fordobling af fluoridbaggrundsniveauerne. Ph.d.-projektets mest overraskende fund er......, at akkumuleringen af fluorid i biofilmsedimentet målt over en time efter en mundskylning med fluorid knapt viste nogen forskel mellem 1.500 og 5.000 ppm fluorid mundskyllevæskerne. Yderligere studier må udforske dette fund og kliniske undersøgelser er påkrævet for at klarlægge de mulige kliniske konsekvenser af de...

  11. ADSORPTIVE REMOVAL OF FLUORIDE FROM WATER USING ...

    African Journals Online (AJOL)

    Preferred Customer

    It requires high capital investment cost and high energy consumption, and is not economical as in the case of the ..... and Temkin isotherm. Freundlich isotherm model assumes unlimited sorption sites which .... energy 13.15 kJ mol-1, which indicates the fluoride removal by nano-AlOOH is chemisorption process. Adsorption ...

  12. Sorption of sulfuryl fluoride by food commodities.

    Science.gov (United States)

    Sriranjini, Venkata-rao; Rajendran, Somiahnadar

    2008-08-01

    The use of sulfuryl fluoride, a structural fumigant for termite and woodborer control, has recently been expanded to treating stored food commodities and food facilities. There is, however, a lack of data on the sorption of sulfuryl fluoride by food commodities. Knowledge about sorption is important in the context of effective treatment and residues. When sulfuryl fluoride was applied at a dose of 50 g m(-3) to various food commodities (total 68) with 300 g per replicate in 0.75 L gas wash bottles (fumigation chambers) at 25 +/- 1 degrees C, in most cases (81%) the gas concentrations in the free space of the commodities exceeded 50 g m(-3) (range 51-80 g m(-3)) at the end of 24 h exposure. In chambers without the substrate, an average concentration of 49.7 g m(-3) was recorded. About 54% of the commodities showed low-level ( 50%). The latter include white oats (terminal gas concentration 17.8 g m(-3)), some of the decorticated split pulses (24.0-29.3 g m(-3)), chickpea flour (26.3 g m(-3)), dried ginger (29.0 g m(-3)), refined wheat flour (30.3 g m(-3)) and coriander powder (40.5 g m(-3)). In unfumigated control commodities, owing to interfering volatiles, Fumiscope readings in the range 0-13 were noted. Sulfuryl fluoride has the advantage of a low or moderate level of sorption with the majority of the food commodities.

  13. Adverse effects of fluoride towards thyroid hormone metabolism

    Directory of Open Access Journals (Sweden)

    Enggar Abdullah Idris MZ

    2008-03-01

    Full Text Available An easily ionized fluoride compound like Sodium Fluoride (NaF has been used thus far as a dental caries prevention substance. However, fluoride ions also have a negative effect because it is very toxic. Several types of research on the effect of fluoride on guinea pigs and human beings indicate the presence synthesis obstruction of T3 and T4 that causes declined production, known as hypothyroidism. Hypothyroidism condition may obstruct tissue growth process and metabolism so as to impact various body organ systems. Preventive efforts against hypothyroidism caused by fluoride include avoiding diffusible fluoride compound intake, like NaF, in a long run systemic use, whereas efforts to overcome fluoride intoxication include consuming food that is rich in calcium, vitamin D, and antioxidant.

  14. FLUORIDE CONTENT OF COMMERCIALLY AVAILABLE SOY MILK PRODUCTS IN THAILAND.

    Science.gov (United States)

    Rirattanapong, Opas; Rirattanapong, Praphasri

    2016-01-01

    Abstract. In Thailand, the consumption of soy milk products is common but there is limited data about their fluoride content. The purpose of this study was to es- timate the fluoride content of soy milk products available in Thailand. Fluoride content was determined for 76 brands of soy milk using a F-ion-specific electrode. The fluoride concentrations ranged from 0.01 to 3.78 μg/ml. The fluoride content was not related to sugar content, soy bean content or the sterilization process. Among 3 brands of soy milk containing tea powder extract, the fluoride content was high (1.25 to 3.78 μg/ml). Most brands of soy milk tested in our study had fluoride content below the optimal daily intake but brands containing tea powder extract if consumed by children may increase their risk for fluorosis.

  15. A theoretical prediction of thermodynamic properties of chlorine fluorides

    International Nuclear Information System (INIS)

    Du, Hongchen; Liu, Yan; Wang, Fang; Zhang, Jianying; Liu, Hui; Gong, Xuedong

    2011-01-01

    Graphical abstract: Correlation between the HOFs obtained from the formation reactions (HOF(FR)) and modified formation reactions (HOF(MFR)). Highlights: → We calculate the heats of formation of nine chlorine fluorides - ClF, ClF 3 , ClF 5 , ClFO, ClFO 2 , ClFO 3 , ClF 3 O 2 , ClF 3 O, and ClF 5 O. → The formation reaction in conjunction with the G3 theory can give accurate results. → ClF, ClF 3 , ClF 5 and ClF 3 O are stable at the room temperature. → ClFO 2 , ClF 3 O 2 and ClF 5 O may be stable at lower temperature. - Abstract: The heats of formation of ClF, ClF 3 , ClF 5 , ClFO, ClFO 2 , ClFO 3 , ClF 3 O 2 , ClF 3 O, and ClF 5 O have been calculated with the help of atomization reaction (AR), formation reaction (FR), and modified formation reaction (MFR) at the G3 and G3X (X = B3, MP2, and MP2B3) levels. FR or MFR in conjunction with the G3 theory can give accurate results close to experimental values. The standard thermodynamic functions of the title compounds have also been evaluated and the results agree well with the available experimental data. Results show that ClF, ClF 3 , ClF 5 and ClF 3 O are stable at the room temperature, and ClFO 2 , ClF 3 O 2 , and ClF 5 O may be stable at lower temperature.

  16. Corrosion behaviour of TiN and ZrN in the environment containing fluoride ions

    Energy Technology Data Exchange (ETDEWEB)

    Joska, Ludek; Fojt, Jaroslav; Hradilova, Monika [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Hnilica, Frantisek [UJP, Prague (Czech Republic); Cvrcek, Ladislav, E-mail: joskal@vscht.c [HVM Plasma, Prague (Czech Republic)

    2010-10-01

    Nowadays, a wide range of materials for human implants is used. To reach the required properties of implants, coatings are applied in some cases. This contribution is focused on the corrosion properties of TiN and ZrN layers on cp-titanium (commercially pure titanium) under environment modelling conditions in an oral cavity. Measurements were done in artificial saliva and a physiological solution unbuffered and buffered to a pH value of 4.2 with the addition of fluoride ions up to 4000 ppm. Standard corrosion electrochemical techniques were applied. Both types of layers were stable in both model saliva and physiological solution with non-adjusted pH. The decrease in pH to 4.2 resulted in a minor decrease of corrosion resistance in all cases, but polarization resistance was still in the order of 10{sup 5} {Omega} cm{sup 2}. An important change in a specimens' behaviour was noticed in the presence of fluoride ions. TiN was stable in the highest concentration of fluorides used. The ZrN layers were destabilized in an environment containing a few hundred ppm of fluoride ions. As for TiN, the decisive factor is the influence of porosity; the corrosion resistance of ZrN is limited. From the corrosion point of view, the application of the TiN-based barrier layers in dental implantology is more advisable than the use of ZrN, provided that the application of a barrier is inevitable.

  17. Effects of fluoridated milk on root dentin remineralization.

    Directory of Open Access Journals (Sweden)

    Wolfgang H Arnold

    Full Text Available The prevalence of root caries is increasing with greater life expectancy and number of retained teeth. Therefore, new preventive strategies should be developed to reduce the prevalence of root caries. The aim of this study was to investigate the effects of fluoridated milk on the remineralization of root dentin and to compare these effects to those of sodium fluoride (NaF application without milk.Thirty extracted human molars were divided into 6 groups, and the root cementum was removed from each tooth. The dentin surface was demineralized and then incubated with one of the following six solutions: Sodium chloride NaCl, artificial saliva, milk, milk+2.5 ppm fluoride, milk+10 ppm fluoride and artificial saliva+10 ppm fluoride. Serial sections were cut through the lesions and investigated with polarized light microscopy and quantitative morphometry, scanning electron microscopy (SEM and energy-dispersive X-ray spectroscopy (EDS. The data were statistically evaluated using a one-way ANOVA for multiple comparisons.The depth of the lesion decreased with increasing fluoride concentration and was the smallest after incubation with artificial saliva+10 ppm fluoride. SEM analysis revealed a clearly demarcated superficial remineralized zone after incubation with milk+2.5 ppm fluoride, milk+10 ppm fluoride and artificial saliva+10 ppm fluoride. Ca content in this zone increased with increasing fluoride content and was highest after artificial saliva+10 ppm fluoride incubation. In the artificial saliva+10 ppm fluoride group, an additional crystalline layer was present on top of the lesion that contained elevated levels of F and Ca.Incubation of root dentin with fluoridated milk showed a clear effect on root dentin remineralization, and incubation with NaF dissolved in artificial saliva demonstrated a stronger effect.

  18. Fluoride release and uptake abilities of different fissure sealants.

    Science.gov (United States)

    Poggio, Claudio; Andenna, Gianluigi; Ceci, Matteo; Beltrami, Riccardo; Colombo, Marco; Cucca, Lucia

    2016-07-01

    The long-term capability of resin sealants and glass ionomer cements to release fluoride is associated to a reduction in pit and fissure caries. The regular use of fluoride varnishes/toothpastes can result in the absorption of fluoride into the sealant. The objective of the present study was to assess the fluoride release/uptake capacities of different fissure sealants. Three different fissure sealants (Fuji Triage/GC, Fissurit FX/Voco and Grandio Seal/Voco) were examined. Ten discs of each material were prepared. Each disc was incubated with distilled water and then the solution analyzed for diluted for fluoride concentration, using a combination of fluoride electrode (OrionGP 1 S/N 13824, Orion Research Inc, Boston, MA, USA) connected to an expandable ion analyzer (Orion 720A, Orion Research Inc, Boston, MA, USA). Standard curves between 1 and 100 ppm F- were used to calibrate the electrode. Cumulative fluoride release was measured on days 1, 2, 3, 5, 7, 21, 35 and 49, then two different fluoride varnishes/pastes (Profluorid Varnish/Voco, MI Paste Plus/GC), were applied to the sealants tested, and fluoride release (after reuptake) was measured on days 56, 70 and 84. Kruskal Wallis test confirmed significant differences in fluoride release between Fuji Triage/GC and Fissurit FX/Voco and Grandio Seal/Voco from day 1 (P 0.05). The GIC-based sealant (Fuji Triage/GC) released significantly more fluoride than the resin sealants tested. The exposure to the fluoridated varnish (Profluorid Varnish) significantly recharged the sealants tested more than the CPP-ACPF toothpaste (MI Paste Plus). Fissure sealants, fluoride release, fluoride uptake, glass ionomer cements.

  19. Water fluoridation in 40 Brazilian cities: 7 year analysis

    Directory of Open Access Journals (Sweden)

    Suzely Adas Saliba MOIMAZ

    2013-01-01

    Full Text Available Objectives Fluoride levels in the public water supplies of 40 Brazilian cities were analyzed and classified on the basis of risk/benefit balance. Material and Methods Samples were collected monthly over a seven-year period from three sites for each water supply source. The samples were analyzed in duplicate in the laboratory of the Center for Research in Public Health - UNESP using an ion analyzer coupled to a fluoride-specific electrode. Results A total of 19,533 samples were analyzed, of which 18,847 were artificially fluoridated and 686 were not artificially fluoridated. In samples from cities performing water fluoridation, 51.57% (n=9,720 had fluoride levels in the range of 0.55 to 0.84 mg F/L; 30.53% (n=5,754 were below 0.55 mg F/L and 17.90% (n=3,373 were above 0.84 mg F/L (maximum concentration=6.96 mg F/L. Most of the cities performing fluoridation that had a majority of samples with fluoride levels above the recommended parameter had deep wells and more than one source of water supply. There was some variability in the fluoride levels of samples from the same site and between collection sites in the same city. Conclusions The majority of samples from cities performing fluoridation had fluoride levels within the range that provides the best combination of risks and benefits, minimizing the risk of dental fluorosis while preventing dental caries. The conduction of studies about water distribution systems is suggested in cities with high natural fluoride concentrations in order to optimize the use of natural fluoride for fluoridation costs and avoid the risk of dental fluorosis.

  20. Towards Rational Design of Functional Fluoride and Oxyfluoride Materials from First Principles

    Science.gov (United States)

    Charles, Nenian

    Complex transition metal compounds (TMCs) research has produced functional materials with a range of properties, including ferroelectricity, colossal magnetoresistance, nonlinear optical activity and high-temperature superconductivity. Conventional routes to tune properties in transition metal oxides, for example, have relied primarily on cation chemical substitution and interfacial effects in thin film heterostructures. In heteroanionic TMCs, exhibiting two chemically distinct anions coordinating the same or different cations, engineering of the anion sub-lattice for property control is a promising alternative approach. The presence of multiple anions provides additional design variables, such as anion order, that are absent in homoanionic counterparts. The more complex structural and chemical phase space of heteroanionic materials provides a unique opportunity to realize enhanced or unanticipated electronic, optical, and magnetic responses. Although there is growing interest in heteroanionic materials, and synthetic and characterization advances are occurring for these materials, the crystal-chemistry principles for realizing structural and property control are only slowing emerging. This dissertation employs anion engineering to investigate phenomena in transition metal fluorides and oxyfluorides compounds using first principles density functional theory calculations. Oxyfluorides are particularly intriguing owing their tendency to stabilize highly ordered anion sublattices as well as the potential to combine the advantageous properties of transition metal oxides and fluorides. This work 1) addresses the challenges of studying fluorides and oxyfluorides using first principles calculations; 2) evaluates the feasibility of using external stimuli, such as epitaxial strain and hydrostatic pressure, to control properties of fluorides and oxyfluorides; and 3) formulates a computational workflow based on multiple levels of theory and computation to elucidate structure

  1. Effect of Magnesium Fluoride on Hydrogenation Properties of Magnesium Hydride

    Directory of Open Access Journals (Sweden)

    Pragya Jain

    2015-11-01

    Full Text Available A cost effective catalyst is of great importance for consideration of MgH2 as potential hydrogen storage material. In this regard, we investigated the catalytic role of alkaline metal fluoride on the hydrogen storage behavior of MgH2. Samples were synthesized by admixing 5 mol % MgF2 into MgH2 powder using planetary ball mill. Hydrogenation measurements made at 335 °C showed that in comparison to only 70% absorption by pure MgH2, catalyzed material absorbed 92% of theoretical capacity in less than 20 min and desorbed completely in almost the same time. Sorption studies done at lower temperatures revealed that complete absorption at temperature as low as 145 °C is possible. This is due to uniform distribution of MgF2 nano particles within the MgH2 powder. X-ray diffraction patterns also showed the presence of stable MgF2 phase that does not decompose upon hydrogen absorption-desorption. Cyclic measurements done at 310 °C showed negligible loss in the overall storage capacity with cycling. These results reveal that the presence of the chemically inert and stable MgF2 phase is responsible for good reversible characteristic and improved kinetics.

  2. Hospitals with greater diversities of physiologically complex procedures do not achieve greater surgical growth in a market with stable numbers of such procedures.

    Science.gov (United States)

    Dexter, Franklin; Epstein, Richard H; Lubarsky, David A

    2018-01-30

    Although having a large diversity of types of procedures has a substantial operational impact on the surgical suites of hospitals, the strategic importance is unknown. In the current study, we used longitudinal data for all hospitals and patient ages in the State of Florida to evaluate whether hospitals with greater diversity of types of physiologically complex major therapeutic procedures (PCMTP) also had greater rates of surgical growth. Observational cohort study. 1479 combinations of hospitals in the State of Florida and fiscal years, 2008-2015. The types of International Classification of Diseases, Ninth revision, Clinical Modification (ICD-9-CM) procedures studied were PCMT, defined as: a) major therapeutic procedure; b) >7 American Society of Anesthesiologists base units; and c) performed during a hospitalization with a Diagnosis Related Group with a mean length of stay ≥4.0days. The number of procedures of each type of PCMTP commonly performed at each hospital was calculated by taking 1/Herfindahl index (i.e., sum of the squares of the proportions of all procedures of each type of PCMTP). Over the 8 successive years studied, there was no change in the number of PCMTP being performed (Kendall's τ b =-0.014±0.017 [standard error], P=0.44; N=1479 hospital×years). Busier and larger hospitals commonly performed more types of PCMTP, respectively categorized based on performed PCMTP (τ=0.606±0.017, Pmarket, the unique contributions of each large teaching hospital performing many different types of PCMTP needs to be considered relative to the combined capabilities of other hospitals in its region. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Stable Isotope Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

  4. Indirect complexometric determination of thorium(IV) using sodium fluoride as masking agent

    International Nuclear Information System (INIS)

    Sreekumar, N.V.; Nazareth, R.A.; Narayana, B.; Hegde, P.; Manjunatha, B.R.

    2002-01-01

    A complexometric method for the determination of thorium(IV) in presence of other metal ions based on the selective masking ability of sodium fluoride towards thorium is described. Thorium(IV) present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated against bismuth nitrate solution at pH 2-3 using xylenol orange as indicator. A known excess of sodium fluoride (5 %) is then added and the EDTA released from the Th-EDTA complex is titrated against standard bismuth nitrate solution. Reproducible and accurate results are obtained for 5 mg to 280 mg of thorium with relative errors ±0.65 % and standard deviations /leq 0.75 mg. The interference of various ions was studied. (author)

  5. Dietary fluoride intake from infant and toddler formulas in Poland.

    Science.gov (United States)

    Opydo-Szymaczek, Justyna; Opydo, Jadwiga

    2011-08-01

    Risk of enamel fluorosis associated with excessive fluoride intake during infancy and early childhood has been widely reported in literature. Results of several studies indicate that infant formula consumption, especially in the form of powdered concentrate, may appreciably increase children's fluoride exposure in optimally fluoridated communities. The aim of the study was to measure fluoride content of infant and toddler formulas available in Poland and to discuss implications of the results. Twenty nine brands of powdered formulas were evaluated. Analyzes were performed with the use of ionselective fluoride electrode (09-37 type) and a RAE 111 chloride-silver reference electrode (MARAT). Results revealed that concentration of fluoride in all products was low (mean 29.0 μg/100 g), and that the formula itself is not a significant source of fluoride exposure. However, when reconstituted with water containing more than 0.5 ppm of fluoride, starting formulas and follow-on formulas may provide a daily fluoride intake of above the suggested threshold for fluorosis. Thus, fully formula-fed infants consuming mother milk substitutes prepared with optimally fluoridated water may be at increased risk of dental fluorosis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Effects of different amine fluoride concentrations on enamel remineralization.

    Science.gov (United States)

    Naumova, E A; Niemann, N; Aretz, L; Arnold, W H

    2012-09-01

    The aim of this study was to investigate the effects of decreasing fluoride concentrations on repeated demineralizing challenges on human enamel. In 24 teeth, 3mm×3mm windows were prepared on the buccal and lingual sides and treated in a cycling demineralization-remineralization model. Remineralization was achieved with 100, 10 and 0.1 ppm fluoride from anime fluoride. Coronal sections were cut through the artificial lesions, and three sections per tooth were investigated using polarized light microscopy and scanning electron microscopy with quantitative element analysis. The morphology of the lesions was studied, and the extensions of the superficial layer and the body of the lesion were measured. Using element analysis, the Ca, P and F content were determined. The body of the lesion appeared remineralized after application of 100 ppm fluoride, while remineralization of the lesion was less successful after application of 10 and 0.1 ppm fluoride. The thickness of the superficial layer increased with decreasing fluoride concentrations, and also the extension of the body of the lesion increased. Ca and P content increased with increasing fluoride concentrations. The effectiveness of fluoride in enamel remineralization increased with increasing fluoride concentration. A consistently higher level of fluoride in saliva should be a goal in caries prevention. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Fluoride concentration from dental sealants: a randomized clinical trial.

    Science.gov (United States)

    Campus, G; Carta, G; Cagetti, M G; Bossù, M; Sale, S; Cocco, F; Conti, G; Nardone, M; Sanna, G; Strohmenger, L; Lingström, P

    2013-07-01

    A randomized clinical trial was performed in schoolchildren (6-7 yrs) to evaluate fluoride concentration in interproximal fluid after the placement of 3 different sealants. The sample consisted of 2,776 children randomly divided: 926 in the high-viscosity Glass-ionomer Cement group (GIC group), 923 in the fluoride Resin-based group (fluoride-RB group), and 927 in the no-fluoride Resin-based group (RB group). In total, 2,640 children completed the trial. Sealants were applied following manufacturer's instructions. Interproximal fluid samples were collected at baseline and 2, 7, and 21 days after application of sealants, by insertion of a standardized paperpoint into the interproximal mesial space of the sealed tooth for 15 seconds. Fluoride concentration was evaluated by means of a fluoride ion-selective electrode. At 2 days after sealant application, fluoride concentration was significantly higher in GIC and fluoride-RB groups compared with that in the RB group (p sealants increased the fluoride concentrations in interproximal fluid more than did a Resin-based sealant containing fluoride.

  8. Release of fluoride from orthodontic adhesives and penetration into enamel.

    Science.gov (United States)

    Suebsureekul, Panita; Viteporn, Smorntree

    2017-05-01

    The purpose of this work was to compare fluoride release from three orthodontic adhesives and fluoride penetration into the enamel surface. A total of 156 extracted human premolar teeth were randomly assigned to three experimental groups and one control group (without bonding) with 39 teeth per group. Brackets were bonded to teeth using Fuji Ortho LC ® , Illuminate ® , or Light Bond ® . The amount of fluoride released (ppm) into artificial saliva was measured by a fluoride ion-selective electrode connected to an ion analyzer on days 1, 3, 7, and 30. Fluoride penetration was investigated after 1, 2, and 3 months; 13 teeth of each group were randomly selected at every period of study and sectioned across the center of the bracket. The surface of the cross-section was studied under the scanning electron microscope, and the fluoride concentration (weight%) at 1, 2, and 3 µm below the outer enamel surface was determined by energy-dispersive X-ray microanalysis. On days 1, 3, 7, and 30, the mean cumulative fluoride release from the three orthodontic adhesives were significantly different (p fluoride, followed by Fuji Ortho LC ® and Light Bond ® . After 1, 2, and 3 months, fluoride penetration into enamel was only found from Fuji Ortho LC ® . The fluoride concentration decreased with depth but there were no significant differences (p > 0.05) over time at all depths. The in vitro study indicated that fluoride release is a common property of the three fluoride-releasing orthodontic adhesives: Illuminate ® , Fuji Ortho LC ® , and Light Bond ® . However, detectable fluoride penetration is a specific property of Fuji Ortho LC ® . Further clinical studies should be undertaken to investigate the benefit of the two adhesives Illuminate ® and Fuji Ortho LC ® on protection of enamel demineralization.

  9. Parabens do not increase fluoride uptake by dental enamel

    Directory of Open Access Journals (Sweden)

    Vanessa Silva Tramontino

    2010-04-01

    Full Text Available Objective: To evaluate whether methylparaben and propylparaben, which present a similar chemical structure, increase fluoride uptake by demineralized dental enamel when present in buffered solutions. Methods: The study comprised an in vitro experiment using blocks of bovine dental enamel with artificial carious lesions. Enamel blocks were exposed to the following treatment (n=12: fluoride solution (200 ppm fluoride - control; solution containing fluoride and 13 mM methylparaben; solution containing fluoride and 13 mM propylparaben in 35% propylene glycol; solution containing fluoride in 35% propylene glycol. All solutions were buffered (0.01 M cacodilate and the pH was adjusted to 6.27. The blocks were exposed to the treatment solutions in the proportion of 2 ml per mm2 of exposed enamel area and fluoride formed was estimated after removing an enamel layer by acid etching. Fluoride extracted was determined by ion specific electrode and the amount of enamel removed was estimated by phosphorus analysis. ANOVA followed by Tukey’s test were used for statistical analysis, with significance level at 5%. Results: The dental blocks of treatment groups containing both parabens and the control group presented similar fluoride concentration in enamel and no statistical difference was observed among them (p>0.05. The dental blocks of treatment group containing fluoride and propylene glycol showed the lowest value of fluoride present in enamel, which was significantly different from the control and fluoride and methylparaben groups (p<0.05. Conclusion: Methyl and propylparaben in a buffered solution do not enhance fluoride uptake by demineralized dental enamel.

  10. Spatial distribution mapping of drinking water fluoride levels in Karnataka, India: fluoride-related health effects.

    Science.gov (United States)

    Chowdhury, Chitta R; Shahnawaz, Khijmatgar; Kumari, Divya; Chowdhury, Avidyuti; Bedi, Raman; Lynch, Edward; Harding, Stewart; Grootveld, Martin

    2016-11-01

    (1) To estimate the concentrations of fluoride in drinking water throughout different zones and districts of the state of Karnataka. (2) To investigate the variation of fluoride concentration in drinking water from different sources, and its relationships to daily temperature and rainfall status in the regional districts. (3) To develop an updated fluoride concentration intensity map of the state of Karnataka, and to evaluate these data in the context of fluoride-related health effects such as fluorosis and their prevalence. Aqueous standard solutions of 10, 100 and 1,000 ppm fluoride (F - ) were prepared with analytical grade Na + /F - and a buffer; TISAB II was incorporated in both calibration standard and analysis solutions in order to remove the potentially interfering effects of trace metal ions. This analysis was performed using an ion-selective electrode (ISE), and mean determination readings for n = 5 samples collected at each Karnataka water source were recorded. The F - concentration in drinking water in Karnataka state was found to vary substantially, with the highest mean values recorded being in the north-eastern zone (1.61 ppm), and the lowest in the south-western one (only 0.41 ppm). Analysis of variance (ANOVA) demonstrated that there were very highly significant 'between-zone' and 'between-districts-within-zones' sources of variation (p water source F - levels within this state. The southern part of Karnataka has low levels of F - in its drinking water, and may require fluoridation treatment in order to mitigate for dental caries and further ailments related to fluoride deficiency. However, districts within the north-eastern region have contrastingly high levels of fluoride, an observation which has been linked to dental and skeletal fluorosis. This highlights a major requirement for interventional actions in order to ensure maintenance of the recommended range of fluoride concentrations (0.8-1.5 ppm) in Karnataka's drinking water

  11. Fluoride ion encapsulation by Mg2+ ions and phosphates in a fluoride riboswitch.

    Science.gov (United States)

    Ren, Aiming; Rajashankar, Kanagalaghatta R; Patel, Dinshaw J

    2012-05-13

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A•U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg(2+) ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.

  12. Fluoride ion encapsulation by Mg2+ and phosphates in a fluoride riboswitch

    Science.gov (United States)

    Ren, Aiming; Rajashankar, Kanagalaghatta R.; Patel, Dinshaw J.

    2012-01-01

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswicthes, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A•U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg2+ ions, which in turn are octahedrally coordinated to waters and five inwardly-pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state defines how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch most likely functions in gene regulation through a transcription termination mechanism. PMID:22678284

  13. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    Burke, F M

    2010-10-01

    The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

  14. Giant flexoelectricity in polyvinylidene fluoride films

    International Nuclear Information System (INIS)

    Baskaran, Sivapalan; Ramachandran, Narayanan; He Xiangtong; Thiruvannamalai, Sankar; Lee, Ho Joon; Heo, Hyun; Chen Qin; Fu, John Y.

    2011-01-01

    Recent studies have shown that giant flexoelectricity may exist in certain elastomers with bent-core molecular structures, which contradicts the previous theoretical estimation that the flexoelectric coupling is small in those materials. In this Letter, we report an analogous phenomenon, i.e., the giant direct flexoelectric effect, observed in a polyvinylidene fluoride (PVDF) film. Our experimental studies indicate that such an enhanced flexoelectric effect might be induced by the interaction between the energy couplings of the apolar and the polar molecular structures of the polymer film under elastic deformation. - Highlights: → Polyvinylidene fluoride (PVDF) film with not fully crystallized α- and β-phases. → Flexoelectric measurement. → Giant direct flexoelectric effect in PVDF.

  15. Coupling NMR with Synchrotron radiation at high temperature for the study of molten fluorides : applied to zirconium fluorides

    International Nuclear Information System (INIS)

    Maksoud, Louis

    2013-01-01

    Molten fluorides are used in Molten Salt Reactors MSR such as the non moderated fast reactor MSFR, where the molten salt LiF-ThF 4 is the fuel and the coolant. The formation of fission products (FP) such as lanthanides, during the reactor operation, possibly modifies the physicochemical properties of the melt. It is therefore important to characterize the melt from the structural and the dynamics point of view in order to determine its properties. Because of problems related to the radioactivity of thorium, as well as requirements related to spectroscopic methods, the system studied in this thesis is the LiF-ZrF 4 -LaF 3 (zirconium and lanthanum are possible FP). The approach followed in this thesis combines measurements by NMR spectroscopy and EXAFS at 850 C with molecular dynamics simulations. In the molten salt, we have shown the existence of zirconium and lanthanum complexes with different coordination numbers, whose proportions depend on the composition. Depending on the content of ZrF 4 , [ZrF 7 ] 3- species are dominant but change slightly and are further connected between each other's via bridging fluorine. The addition of LaF 3 to the mixture stabilizes the 7 coordination number around the zirconium and tends to enrich the environment of lanthanum with fluorides. A medium-range order is established between the various complexes containing zirconium and lanthanum due to bridging fluorine. Species dynamics is slower when the amount of either ZrF 4 or LaF 3 is higher. We noted a significant effect on the structure and dynamics of species starting 10 mol% LaF 3 added to the medium. The data obtained by this novel approach concerning the chemistry of the molten salt in MSR containing FP, are fundamental to improve the separation of these products and optimize the process. (author)

  16. Metathesis synthesis and characterization of complex metal fluoride ...

    Indian Academy of Sciences (India)

    Administrator

    Sivakumar et al 2004; Mandal and Gopalakrishnan 2005). Although metathesis reactions may initiate spontane- ously .... cal lithography are needed (Sahnoun et al 2005). KMF3 materials with perovskite structures are ... (Knox 1961; Machin et al 1963; Pari et al 1994) and shown in figure 5. The KMF3 compounds are anti-.

  17. The effective use of fluorides in public health

    DEFF Research Database (Denmark)

    Jones, Sheila; Burt, Brian A; Petersen, Poul Erik

    2005-01-01

    and development was concerned with waterborne fluorides, both naturally occurring and added, and their effects on the prevalence and incidence of dental caries and dental fluorosis. In the latter half of the 20th century, the focus of research was on fluoride toothpastes and mouth rinses. More recently...... and their families, and the issue of cost. We recommend that a community should use no more than one systemic fluoride (i.e. water or salt or milk fluoridation) combined with the use of fluoride toothpastes, and that the prevalence of dental fluorosis should be monitored in order to detect increases in or higher......Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research...

  18. Necessity to review the Brazilian regulation about fluoride toothpastes

    Science.gov (United States)

    Cury, Jaime Aparecido; Caldarelli, Pablo Guilherme; Tenuta, Livia Maria Andaló

    2015-01-01

    The aim of this study was to evaluate the adequacy of the Brazilian legislation about fluoride toothpaste. A search was conducted in LILACS, Medline and SciELO databases about the fluoride concentration found in Brazilians toothpastes, using descriptors on health. Publications since 1981 have shown that some Brazilian toothpastes are not able to maintain, during their expiration time, a minimum of 1,000 ppm F of soluble fluoride in the formulation. However, the Brazilian regulation (ANVISA, Resolution 79, August 28, 2000) only sets the maximum total fluoride (0.15%; 1,500 ppm F) that a toothpaste may contain but not the minimum concentration of soluble fluoride that it should contain to have anticaries potential, which according to systematic reviews should be 1,000 ppm F. Therefore, the Brazilian regulation on fluoride toothpastes needs to be revised to assure the efficacy of those products for caries control. PMID:26487295

  19. Fluoride content of clay minerals and argillaceous earth materials

    Science.gov (United States)

    Thomas, Josephus; Glass, H.D.; White, W.A.; Trandel, R.M.

    1977-01-01

    A reliable method, utilizing a fluoride ion-selective electrode, is described for the determination of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ±5% at different levels of fluoride concentration.Data are presented for various clay minerals and for the geode kaolinite (125 ppm). The clay stratum immediately overlying a fluorite mineralized zone in southern Illinois was found to have a higher fluoride content than the same stratum in a nonmineralized zone approximately 1 mile away. Nonmarine shales in contact with Australian coals were found to be lower in fluoride content than were marine shales in contact with Illinois coals.It is believed that, in certain instances, peak shifts on DTA curves of similar clay minerals are the result of significant differences in their fluoride content.

  20. Fluoride-sulfophosphate glasses as hosts for broadband optical amplification through transition metal activators.

    Science.gov (United States)

    Wang, W C; Le, Q H; Zhang, Q Y; Wondraczek, L

    2017-08-21

    Unusually stable multi-anion glasses of the fluoride-sulfophosphate type (FPS) are introduced as a new host material for optically active cation species. Despite a notoriously low polymerization grade, anion mixing in this glass system enables facile manufacture of bulk or fiber devices which combine several advantages of fluoride and phosphate glasses while using the stabilizing effect of sulfate additions. Using the example of chromium doping, we demonstrate broad red photoluminescence at 734 nm and inhomogeneous broadening of the R -line at 694 nm, originating from the 4 T 2 → 4 A 2 and 2 E → 4 A 2 transitions of Cr 3+ , respectively. The luminescence mechanism is further analyzed on the basis of the corresponding Tanabe-Sugano diagram. Tailored through chemical composition, internally nucleated precipitation of a nanocrystalline fluoride phase enables switching between high-field and low-field configurations of the Cr 3+ ion, resulting in the specific emission properties and setting the path towards FPS-based optical devices.

  1. Fluoride varnish may improve white spot lesions.

    Science.gov (United States)

    Stafford, Gary L

    2011-12-01

    A randomised, parallel-group, controlled clinical trial. The test group had fluoride varnish applied onto the tooth surfaces with WSLs using a miniature cotton swab or brush and advised not to brush for four hours. The control group had saline solution applied. Status of the WSLs were assessed using a DIAGNOdent pen (KaVo, Biberach, Germany). Of the 110 participants recruited, 14 dropped out between the debonding and the six-month recall visit. There were statistically significant differences between the mean DIAGNOdent readings of the two groups at the three-month (P<0.05) and at the six-month follow-up visits (P<0.01). No adverse response or safety concerns in the use of fluoride varnish were reported by any of the subjects. A greater decrease in DIAGNOdent pen readings was found in the test group during the first six months after debonding. This may be taken to imply an improvement in the WSLs. Thus, topical fluoride varnish application appears to be a good method to treat WSLs and should be advocated as a routine measure after orthodontic treatment.

  2. Biological effects data: Fluoride and sulfur dioxide

    Energy Technology Data Exchange (ETDEWEB)

    McMechan, K.J. (ed.); Holton, R.L.; Ulbricht, R.J.; Morgan , J.B.

    1975-04-01

    The Alumax Pacific Aluminum Corporation has proposed construction of an aluminum reduction facility near Youngs Bay at Warrenton, Oregon. This report comprises one part of the final report to Alumax on a research project entitled, Physical, Chemical and Biological Studies of Youngs Bay.'' It presents data pertaining to the potential biological effects of fluoride and sulfur dioxide, two potentially hazardous plant-stack emissions, on selected aquatic species of the area. Companion volumes provide a description of the physical characteristics the geochemistry, and the aquatic animals present in Youngs Bay and adjacent ecosystems. An introductory volume provides general information and maps of the area, and summarizes the conclusions of all four studies. The data from the two phases of the experimental program are included in this report: lethal studies on the effects of selected levels of fluoride and sulfur dioxide on the survival rate of eleven Youngs Bay faunal species from four phyla, and sublethal studies on the effects of fluoride and sulfur dioxide on the rate of primary production of phytoplankton. 44 refs., 18 figs., 38 tabs.

  3. Mortality and cancer morbidity after heavy occupational fluoride exposure

    DEFF Research Database (Denmark)

    Grandjean, P; Juel, K; Jensen, Ole Møller

    1985-01-01

    A cohort of 431 male cryolite workers employed for at least six months between 1924 and 1961 was identified from personnel records at the Copenhagen cryolite factory. During this period, heavy fluoride exposure resulted in at least 74 cases of skeletal fluorosis. All workmen in the cohort were......, a possible residual effect of fluoride cannot be excluded. However, any major carcinogenic effect of heavy fluoride exposure would be very unlikely....

  4. Mortality and cancer morbidity after heavy occupational fluoride exposure

    DEFF Research Database (Denmark)

    Grandjean, P; Juel, K; Jensen, Ole Møller

    1985-01-01

    A cohort of 431 male cryolite workers employed for at least six months between 1924 and 1961 was identified from personnel records at the Copenhagen cryolite factory. During this period, heavy fluoride exposure resulted in at least 74 cases of skeletal fluorosis. All workmen in the cohort were fo......, a possible residual effect of fluoride cannot be excluded. However, any major carcinogenic effect of heavy fluoride exposure would be very unlikely....

  5. Onderzoek naar de bepaling van fluoride in een doorstroomsysteem

    OpenAIRE

    Neele J; Nagtegaal-Wouterse GWM; Reijnders HFR

    1989-01-01

    Een snelle methode voor de bepaling van fluoride in een doorstroomsysteem met potentiometrische detectie en een lage onderste analysegrens is ontwikkeld. De mate waarin fluoride uit fluoride-verbindingen wordt vrijgemaakt door complexvormende stoffen is gevolgd om vast te stellen hoeveel tijd hiervoor nodig is. Enkele methode-karakteristieken zoals herhaalbaarheid, onderste analysegrens, bovenste analysegrens, storing door enige componenten en vergelijkbaarheid zijn bepaald. In een volume van...

  6. Approaches to the accurate characterization of high purity metal fluorides and fluoride glasses

    Science.gov (United States)

    Beary, E. S.; Paulsen, P. J.; Rains, T. C.; Ewing, K. J.; Jaganathan, J.; Aggarwal, I.

    1990-11-01

    The analytical challenges posed by the measurement of trace contaminants in high purity metal fluorides require that innovative chemical preparation procedures be used to enhance existing instrumental techniques. The instrumental techniques used to analyze these difficult matrices must be sensitive enough to detect extremely low levels of trace impurities, and the background interferences derived from the matrix (metal fluoride or glass) must be minimized. A survey of analytical techniques that have the necessary characteristics to analyze these materials will be given. In addition, means of controlling the chemical blank will be presented. Mass and atomic spectrometric techniques will be discussed, specifically graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Analytical procedures using GFAAS and ICP-MS have been developed to determine sub ppb (part per billion) levels of contaminants in high purity fluoride materials.

  7. Band structure and phonon properties of lithium fluoride at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, J. M., E-mail: amitjignesh@yahoo.co.in [Government Engineering College, Gandhinagar 382028, Gujarat (India); Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India); Joshi, Mitesh [Government Polytechnic for Girls, Athwagate, Surat395001, Gujarat (India); Gajjar, P. N., E-mail: pngajjar@rediffmail.com [Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India)

    2016-05-23

    High pressure structural and electronic properties of Lithium Fluoride (LiF) have been studied by employing an ab-initio pseudopotential method and a linear response scheme within the density functional theory (DFT) in conjunction with quasi harmonic Debye model. The band structure and electronic density of states conforms that the LiF is stable and is having insulator behavior at ambient as well as at high pressure up to 1 Mbar. Conclusions based on Band structure, phonon dispersion and phonon density of states are outlined.

  8. Band structure and phonon properties of lithium fluoride at high pressure

    International Nuclear Information System (INIS)

    Panchal, J. M.; Joshi, Mitesh; Gajjar, P. N.

    2016-01-01

    High pressure structural and electronic properties of Lithium Fluoride (LiF) have been studied by employing an ab-initio pseudopotential method and a linear response scheme within the density functional theory (DFT) in conjunction with quasi harmonic Debye model. The band structure and electronic density of states conforms that the LiF is stable and is having insulator behavior at ambient as well as at high pressure up to 1 Mbar. Conclusions based on Band structure, phonon dispersion and phonon density of states are outlined.

  9. Modification of the x-ray diffraction efficiency of lithium fluoride crystals by surface treatment

    International Nuclear Information System (INIS)

    Sellick, B.O.

    1976-01-01

    Convex-curved crystals of lithium fluoride demonstrate good dispersion and efficiency when used in reflection for x-ray spectral analysis. The crystals are stable and reasonably unaffected by harsh environments. In addition, they are mechanically strong, easily cleavable or machinable, and plastically deformable with heat. In the present study, flat crystal wafers were left either clear as cleaved or were subjected to surface treatment by sandblasting or lapping. Some wafers were then bent in a press mold to obtain convex-curved crystals of differing radii. The diffraction efficiency data presented show how surface treatment affects the efficiency of these various crystals when used as x-ray diffracting agents

  10. Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

    Science.gov (United States)

    Ismael, Chiamenti; Francesca, Bonfigli; Anderson, S. L. Gomes; Rosa, Maria Montereali; Larissa, N. da Costa; Hypolito, J. Kalinowski

    2014-01-01

    Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F2 and F3+ color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10-3-10-4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF.

  11. KINETICS OF SORPTION OF FLUORIDE ON CALCINED MAGNESITE IN BATCH

    DEFF Research Database (Denmark)

    Singano, J. J.; Mashauri, D. A.; Mtalo, F. W.

    1997-01-01

    on first-order reaction with respect to the concentration of fluoride. The rate constant is directly proportional to the dosage. The model takes into accounts the lag time observed. The kinetical model can be described for any given dosage and initial fluoride concentration in the water. The reaction rate...... parameter, K, varies however slightly for different initial concentrations of fluoride in the water and different dosage of calcined magnesia. These relationships are described separately by two linear equations. It is discussed that the observed lag time is due to the fact that magnesia cannot remove...... fluoride without hydrolysis, and it is probably this hydrolysis which constraint the start of the removal....

  12. Effects of oral doses of fluoride on nestling European starlings

    Science.gov (United States)

    Fleming, W.J.; Grue, C.E.; Schuler, C.A.; Bunck, C.M.

    1987-01-01

    Nestling European starlings (Sturnus vulgaris), raised and fed by free-living adults, were given daily oral doses of either distilled water, 193 mg sodium as Na2CO3 per kg of body weight (sodium control group), or 6, 10, 13, 17,23, 30, 40, 80, 160 mg of the fluoride ion as NaF in distilled water per kg of body weight (mg/kg). Dosing began when nestlings were 24-48 hr old and continued for 16 days. The 24-hr LD50 of fluoride for day-old starlings was 50 mg/kg. The 16-day LD50 was 17 mg/kg. The sodium control group did not differ from the water control group with respect to any of the measured variables. Growth rates were significantly reduced in the 13 and 17 mg of fluoride/kg groups; weights of birds given higher dose levels were omitted from growth comparisons because of high, fluoride-induced mortality. Although pre-fledging weights for the 10, 13, and 17 mg of fluoride/kg groups averaged 3.6 to 8.6% less than controls at 17 days, this difference was not significant. Feather and bone growth of the fluoride and control groups were not different, except for keel length measured at 17 days of age which averaged less in the fluoride groups. Liver and spleen weights were not affected by fluoride treatments. No histological damage related to fluoride treatments was found in liver, spleen, or kidney. The logarithm of bone fluoride and magnesium concentration increased with the logarithm of increasing fluoride treatment levels and were significantly correlated with each other. Fluoride treatments had no effect on percent calcium or phosphorus in bone or plasma alkaline phosphatase activity. Oral doses of fluoride appear to be more toxic than equivalent dietary levels. Most birds probably acquire fluoride through their diet. Therefore, the results of the study may overestimate the potential effects of fluorides on songbirds living in fluoride-contaminated environments.

  13. Formulation and Characterization of Antibacterial Fluoride-releasing Sealants

    Science.gov (United States)

    Fan, Yuwei; Townsend, Janice; Wang, Yapin; Lee, Eun Chee; Evans, Katie; Hender, Erica; Hagan, Joseph L.; Xu, Xiaoming

    2013-01-01

    Purpose The purpose of this study was to formulate and characterize experimental antibacterial fluoride-releasing sealants and compare them with commercial sealants for fluoride release, recharge, adhesion, and microleakage. Methods Two experimental sealants (Exp-1, Exp-2) containing a synthesized antibacterial fluoride-releasing monomer and fluoride-releasing filler were formulated. Exp-2 also contained NovaMin nanoparticles. Commercial sealants Clinpro (CL) FluoroShield (FS), and SeLECT Defense (E34) were also included. Fluoride release from disk samples in deionized water was measured daily using an ion-selective electrode for 14 days, and after recharging with Neutra-Foam (2.0% sodium fluoride), fluoride was measured for 5 days. Microtensile bonding strengths (MTBS) to enamel were tested after 24-hour storage in water at 37°C or thermocycling 5-55°C for 1,000 cycles. A microleakage test was conducted on extracted teeth using a dye-penetration method. The data were analyzed using analysis of variance with the Tukey’s honestly significant difference test and Kruskal-Wallis test. Results Exp-1 and Exp-2 had significantly higher fluoride release and recharge capabilities than CL and FL (P<.05). All tested sealants had similar MTBS before and after thermocycling. Exp-2 and Exp-1 had significantly lower microleakage scores (P<.05) than other groups. Conclusion The experimental sealants had higher fluoride release and recharge capabilities and similar or better retention than commercial sealants. PMID:23635887

  14. Fluoride content and labelling of toothpastes marketed in India.

    Science.gov (United States)

    Thakkar, V P; Rao, A; Rajesh, G; Shenoy, R; Pai, M

    2015-09-01

    To enumerate the fluoride content and labelling practices of toothpastes marketed in India and to determine if the content is in accordance with the information provided on the packaging. In vitro analysis of total and free available fluoride in 5 adult and 5 children's fluoride toothpastes in India using fluoride ion electrode. Information on the tube and carton was checked to assess the labelling. The mean Total Fluoride concentrations (TF) in the toothpastes labelled 1,000 ppm, 500ppm and 458 ppm were 1,000, 500 and 449mg/L (sd values 3, 5 and 4mg/L) respectively. The toothpastes' Total Soluble Fluoride (TSF) concentration was generally slightly less than the TF concentration. Overall mean percentage of TSF concentration was 94% sd 9%. The mean percentage of TSF concentration in SMFP (sodium monofluorophosphate)/CaCO3 (calcium carbonate) containing toothpastes was 86% sd 16% while that in NaF (sodium fluoride)/Si (silica) based toothpastes was 98% sd 1% and 95% sd 1% in the remaining toothpastes with unknown abrasive. NaF/Si based toothpastes had more TSF concentration than the others (ptoothpastes. The available fluoride content of one of the ten toothpastes was substantially less than the total fluoride content. Although the toothpastes were labelled following the guidelines of the regulatory body of India, 3 of the 10 failed to mention the abrasive present.

  15. Stable convergence and stable limit theorems

    CERN Document Server

    Häusler, Erich

    2015-01-01

    The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

  16. The effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation.

    Science.gov (United States)

    Lippert, Frank

    2017-08-01

    The aim was to investigate the effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation (EFU) under pH cycling conditions. Human enamel specimens were demineralized at 37°C for 24h using a pH 5.0 solution containing 50mM lactic acid and 0.2% Carbopol 907 which was 50% saturated with respect to hydroxyapatite. Lesions were assigned to nine treatment groups (n=16) based on Knoop surface microhardness indentation length. aqueous solutions were: placebo, 11.9mM sodium fluoride (F), 23.8mM sodium fluoride (2×F), 1.1mM strontium chloride hexahydrate (Sr), 1.1mM F theobromine, Sr+theobromine, F+Sr, F+theobromine, F+Sr+theobromine. Lesions were pH cycled for 5d (daily protocol: 3×1min-treatment; 2×60min-demineralization; 4×60min & overnight-artificial saliva). Knoop indentation length was measured again and%surface microhardness recovery (%SMHr) calculated. EFU was determined using the acid-etch technique. Data were analysed using ANOVA. Model showed fluoride dose-response for both variables (2×F>F>placebo). For%SMHr, F+Sr+/-theobromine resulted in more rehardening than F, however less than 2×F. F+theobromine was similar to F. For EFU, F+Sr was inferior to F, F+theobromine and F+Sr+theobromine which were similar and inferior to 2×F. In absence of fluoride, Sr, theobromine or Sr+theobromine were virtually indistinguishable from placebo and inferior to F. It can be concluded that a) strontium aids rehardening but not EFU and only in presence of fluoride; b) theobromine does not appear to offer any anti-caries benefits in this model; c) there are no synergistic effects between strontium and theobromine in the presence or absence of fluoride. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Cariostatic effect of fluoride-containing restorative materials associated with fluoride gels on root dentin

    Science.gov (United States)

    BORGES, Fernanda Tavares; CAMPOS, Wagner Reis da Costa; MUNARI, Lais Sant'ana; MOREIRA, Allyson Nogueira; PAIVA, Saul Martins; MAGALHÃES, Claudia Silami

    2010-01-01

    Secondary caries is still the main cause of restoration replacement, especially on the root surface Objective This in vitro study evaluated the cariostatic effects of fluoride-containing restorative materials associated with fluoride gels, on root dentin. Materials and Methods A randomized complete block design was used to test the effects of the restorative systems, fluoride regimes and the interactions among them at different distances from restoration margins. Standardized cavities were prepared on 240 bovine root specimens and randomly assigned to 15 groups of treatments (n=16). Cavities were filled with the following restorative materials: Ketac-Fil (3M-ESPE); Vitremer (3M-ESPE); Dyract/Prime & Bond NT (Dentsply); Charisma/Gluma One Bond (Heraeus Kulzer) and the control, Z250/Single Bond (3M-ESPE). The specimens were subjected to a pH-cycling model designed to simulate highcaries activity. During the cycles, 1.23% acidulated phosphate fluoride, 2.0% neutral sodium fluoride or deionized/distilled water (control) was applied to the specimens for 4 min. The surface Knoop microhardness test was performed before (KHNi) and after (KHNf) the pH cycles at 100, 200 and 300 mm from the margins. Dentin microhardness loss was represented by the difference in initial and final values (KHNi - KHNf). Data were analyzed by Friedman's and Wilcoxon's tests, ANOVA and Tukey's test (α=5%). Results The interaction of restorative systems and topical treatments was not significant (p=0.102). Dentin microhardness loss was lowest closer to the restoration. Ketac-fil presented the highest cariostatic effect. Vitremer presented a moderate effect, while Dyract and Charisma did not differ from the control, Z250. The effects of neutral and acidulated fluoride gels were similar to each other and higher than the control. Conclusion Conventional and resin-modified glass ionomer cements as well as neutral and acidulated fluoride gels inhibit the progression of artificial caries adjacent to

  18. High phosphate content significantly increases apatite formation of fluoride-containing bioactive glasses.

    Science.gov (United States)

    Mneimne, Mohammed; Hill, Robert G; Bushby, Andrew J; Brauer, Delia S

    2011-04-01

    Bioactive glass-containing toothpastes for treating dentine hypersensitivity work by precipitating hydroxycarbonate apatite (HCA) onto the tooth surface, but concerns exist over the long-term durability of HCA in the mouth. Fluoride-containing bioactive glasses form fluorapatite (FAp) in physiological solutions, which is more chemically stable against acid attack. The influence of phosphate content on apatite formation was investigated by producing a low-phosphate (about 1 mol% P(2)O(5)) and a high-phosphate (about 6 mol%) series of melt-derived bioactive glasses in the system SiO(2)P(2)O(5)CaONa(2)O; increasing amounts of CaF(2) were added by keeping the ratio of all other components constant. pH change, ion release and apatite formation during immersion in Tris buffer at 37°C over up to 7 days were investigated. Crystal phases formed in Tris buffer were characterized using infrared spectroscopy, X-ray diffraction and solid-state nuclear magnetic resonance (NMR) spectroscopy. An increase in phosphate or fluoride content allowed for apatite formation at lower pH; fluoride enhanced apatite formation due to lower solubility of FAp compared to hydroxyapatite or HCA. High phosphate content glasses formed apatite significantly faster (within 6h) than low phosphate content glasses (within 3 days). In addition, an increase in phosphate content favoured apatite formation rather than fluorite (CaF(2)). (19)F magic angle spinning NMR showed the apatite formed by fluoride-containing glasses to be FAp, which makes these glasses of particular interest for dental applications. This study shows that by varying the phosphate content, the reactivity and apatite formation of bioactive glasses can be controlled successfully. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. PREPARATION AND CHARACTERIZATION OF STRONTIUM FLUORIDE POWDERS ACTIVATED BY NEODYMIUM FLUORIDE

    Directory of Open Access Journals (Sweden)

    S. V. Kuznetsov

    2015-07-01

    Full Text Available Subject of Study. The paper deals with preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry. Method. Nitrate of strontium, neodymium nitrate hexahydrate, with the content equal to 99. 99 % of the basic substance and ammonium fluoride were used as the source of substances. Activated powders of strontium fluoride were obtained by the method of deposition from aqueous solutions by washing the precipitate with a solution of ammonium fluoride, taken over 114 - 120% from stoichiometry. The washed precipitate was centrifuged for 5-7 min, dried in the air at 30-350 C. Heat treatment of the dried precipitate was carried out in two stages: the first stage at the temperature of 200- 2500 C for 0.5-1 hour, the second one at 550- 6000 C for 2-3 hours. X-ray analysis of the synthesized samples was carried out on a Bruker D8 Advance diffractometer, radiation Cu K. The size and shape measuring of the particles of activated strontium fluoride was carried out by means of electron microscope Carl Zeiss NVision 40. The content of neodymium in activated powders of strontium fluoride was determined by the method of spectral emission analysis on the device LEA - S500. Chemical analysis for determination of ammonium ion (NH4+ content in the obtained samples was performed by the method of Kjeldahl. Calculations of lattice parameters, size of coherent scattering regions and the values of micro-deformations were carried out by TOPAS program. Main Results. Preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry, provides obtaining the firm solution Sr1-x-yNdx(NH4yF2+x-y of the cubic fluorite structure. It has been found out that the morphology and size of the resulting product depend on the quantity of

  20. Effect of brushing on fluoride release from 3 bracket adhesives.

    Science.gov (United States)

    Staley, Robert N; Mack, Steven J; Wefel, James S; Vargas, Marcos A; Jakobsen, Jane R

    2004-09-01

    The purpose of this in vitro study was to compare fluoride ion release from 3 orthodontic bracket adhesives with and without brushing the bracketed teeth with a fluoridated dentifrice. The bracket adhesives included a light-cured composite resin (Transbond; 3M Unitek, Monrovia, Calif), a fluoride-releasing composite resin (Advance; L D Caulk Division, Dentsply International, Milford, Del), and a resin-modified glass ionomer (Fuji Ortho LC; GC America, Alsip, Ill). The teeth in the control group were not bonded with brackets. Sixty extracted human teeth were randomly assigned to 6 groups of 10 each: (1) Transbond, brushed; (2) Advance, brushed; (3) Advance, not brushed; (4) Fuji, brushed; (5) Fuji, not brushed; and (6) control, brushed. After bonding, each tooth was placed in a sealed plastic test tube containing 4 ml of deionized water. The toothpaste used in brushing contained 0.15% weight per volume sodium fluoride, 1500 parts per million parts fluoride (Winter-fresh gel; Colgate-Palmolive Co., New York, NY). Brushing began 24 hours after the teeth were bonded and placed in deionized water. After brushing, the teeth were thoroughly rinsed with deionized water and returned to a sealed test tube. Fluoride measurements were taken before brushing began, at intervals of 72 hours for 22 days, and 90 and 93 days after bonding. Findings included: (1) brushing significantly increased the release of fluoride ions from the teeth in the composite resin and control groups, (2) the enamel crowns of the unbonded control teeth absorbed and re-released a substantial amount of fluoride ions obtained from the toothpaste, (3) the brushed group of teeth bonded with the fluoride-releasing composite resin released significantly more fluoride on the last 4 days that measurements were taken after brushing than the nonbrushed group bonded with the same adhesive, (4) the brushed group of teeth bonded with the resin-modified glass ionomer released significantly more fluoride on the last 4

  1. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-01-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), ClO 2 + RuF 6 - , a new compound well idendified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  2. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-10-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), CIO 2 + RuF 6 - , a new compound well identified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  3. stableGP

    Data.gov (United States)

    National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

  4. The Reactivity of Stable Metallacyclobutenes and Vinylcarbenes

    OpenAIRE

    Holland, Ryan Lynn

    2016-01-01

    Chapter 1. Historical Development of Stable Metallacyclobutenes Fred Tebbe and co-workers synthesized the first stable metallacyclobutene complexes in the late 1970’s by treatment of an intermediate titanium methylene species – later popularized as the “Tebbe reagent” – with acetylenes. Robert Grubbs at Caltech further studied this system, using it to detail a degenerate metathesis reaction and to isolate a metallacyclobutane complex – which was implicated in the emerging field of alkene meta...

  5. Fluoride in black and green tea ( Camellia sinensis ) infusions in ...

    African Journals Online (AJOL)

    The fluoride contents in the infusions of 21 commercially available Ethiopian and imported black and green tea brands; in leaf and bag forms was determined by a fluoride ion-selective electrode method. Of the samples analyzed twelve were products from Ethiopia and the remaining nine were imported tea brands.

  6. Computational investigation of the role of fluoride in Tamao oxidations

    DEFF Research Database (Denmark)

    Mader, Mary M.; Norrby, Per-Ola

    2002-01-01

    The Tamao oxidation of alkoxysilanes was investigated computationally to determine the role of fluoride. a key additive. in this reaction. A sequence of fluoride equilibria as well as possible transition states. mediated by basic and neutral peroxide, respectively, were examined, and a potential ...

  7. Poisoning by coal smoke containing arsenic and fluoride

    Energy Technology Data Exchange (ETDEWEB)

    An, D.; He, Y.G.; Hu, Q.X. [Guizhou Sanitary and Epidemiological Station, Guiyang (China)

    1997-02-01

    An investigation was made into a disease involving skin pigmentation, keratosis of the hands and feet, dental discoloration, and generalized bone and joint pain, stiffness and rigidity, in the village of Bazhi, Zhijin County, Ghizhou Province, People`s Republic of China. Measurements were made of the arsenic and fluoride levels of coal, water, air, food, urine and hair in Bazhi and a control village, Xinzhai, in which coal with a low arsenic content was used. Up to 188 people, including children, in Bazhi and 752 in Xinzhai, were examined for the presence of chronic arsenium, skeletal fluorosis, dental fluorosis and electrocardiogram abnormalities. The coal in Bazhi was found to contain high levels of arsenic and fluoride resulting, after burning in homes without an adequate chimney systems, in pollution of air and food with arsenic and fluoride. The coal in Xinzhai did not cause arsenic pollution but did produce a higher level of fluoride pollution. It was concluded that the endemic disease in Bazhi was caused by pollution by coal smoke containing arsenic and fluoride. It is suggested that arsenic may act synergistically with fluoride so that a lower level of fluoride may produce fluoride toxicity with dental and skeletal fluorosis.

  8. Fluoride release by glass ionomer cements, compomer and giomer

    Directory of Open Access Journals (Sweden)

    Sayed Mostafa Mousavinasab

    2009-01-01

    Conclusion:Fuji IX, Fuji VII, Fuji IX Extra, and Fuji II LC released higher amounts of fluoride compared to Beautifil and Dyract Extra in this study. It seems that the extent of the glass ionomer matrix plays an important role in determining the fluoride releasing ability of glass ionomer cement materials.

  9. Fluoride uptake from restorative dental materials by human enamel

    International Nuclear Information System (INIS)

    Forsten, L.; Rytoemaa, I.; Anttila, A.; Keinonen, J.

    1976-01-01

    The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials ; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19 F (p, αγ) 16 O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts 10 6 . All materials, except the composite, increased clearly the fluoride content of the underlying enamel. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel. (author)

  10. Radiation-induced grafting of vinyl fluoride to polyacrylonitrile fibers

    International Nuclear Information System (INIS)

    Asamov, M.K.; Ziyaev, A.L.; Yul'chibaev, A.A.; Usmanov, Kh.U.

    1981-01-01

    Experimental data on gamma-radiation grafting of vinyl fluoride to polyacrylonitrile fibers in the presence of some organic liquids are given. It is shown, that the presence of chloroform vapours in the system produce sensitizing effect. Grafting of vinyl fluoride to polyacrylonitrile fibers considerably increases their thermal stability, lengthening and decreases shrinkage [ru

  11. Study of Fluoride Glasses Devitrification-Based Magnesium ...

    African Journals Online (AJOL)

    The kinetics of devitrification of fluoride glasses stabilized by magnesium fluoride when heated for some time between the glass transition and melting temperatures. The crystallization kinetics of AlF3-YF3-PbF2-CdF2-MgF2 glass prepared by melting the halide powders were studied by differential scanning calorimetry ...

  12. Characterization and fluoride uptake studies of nano-scale iron ...

    African Journals Online (AJOL)

    ... the studied concentration range of 10-30 mg/L. The high loading capacity points towards the potential of this adsorbent for fluoride removal from aqueous streams. Keywords: Fluoride, nano-iron oxide hydroxide, adsorption, kinetics, isotherm study. International Journal of Engineering, Science and Technology, Vol. 2, No.

  13. Studies on the comparative effect of sodium fluoride on collagen ...

    African Journals Online (AJOL)

    use

    2011-12-12

    Dec 12, 2011 ... The fluoride ion comes from the element fluorine. Fluo- rine, the 17th most abundant element in the earth's crust, is a gas and never occurs in a free state in nature. Fluorine exists only in combination with other elements as fluoride compounds, which are constituents of mine- rals in rocks and soil (Dhar and ...

  14. Fluoride distribution in different environmental segments at Hirakud ...

    African Journals Online (AJOL)

    Administrator

    distances from the pollution source. Fluoride levels in surface water varies according to geographical location and proximity to emission sources. Surface water concentrations generally range from 0.01 - 0.3 ppm. Seawater contains more fluoride than fresh water, with concentrations ranging from 1.2 - 1.5 mg/l. Higher levels.

  15. The uptake of hydrogen fluoride by a forest

    International Nuclear Information System (INIS)

    Murphy, C.E. Jr.

    1980-01-01

    A mathematical model of hydrogen fluoride (HF) deposition and accumulation of fluoride in a Eucalyptus rostrata forest has been developed. The model is based on tree physiology and meteorological principles. The data base for the model was derived from a literature survey of the physiological characteristics of E. rostrata and similar eucalyptus species and from current knowledge of meteorological processes in plant canopies

  16. Influence of fluoride on the electrochemical behvior of a new ...

    African Journals Online (AJOL)

    % NaCl as well as in 0.9%NaCl containing fluoride and even in acidified 0.9% NaCl free of fluoride ion. Very low corrosion current densities and high impedance values were obtained, indicating the passive behavior of the alloy. An active state ...

  17. Fluoride removal from water by zirconium (IV) doped chitosan bio ...

    African Journals Online (AJOL)

    Water containing fluoride above 1.5 mg/L leads to health and environmental harms that creates skeletal and dental fluorosis. Adsorption technique prominently removes fluoride from water and its competence is reliant on development of recyclable, environmentally benign adsorbents. Many reported sorbents for ...

  18. Optical detection of sodium salts of fluoride, acetate and phosphate ...

    Indian Academy of Sciences (India)

    cal systems and they are also of health concern.1,2 Many synthetic chromogenic and/or fluorogenic sensors for fluoride ... not applicable in many bio-analytical applications. Of course, colourimetric detection of fluoride in ..... Hursthouse M B, Light M E, Shi A J 2002 Chem. Commun. 758; (c) Camiolo S, Gale P A, Hursthouse.

  19. The occurrence of fluoride in South African groundwater: A water ...

    African Journals Online (AJOL)

    The fluoride data were obtained by extracting fluoride groundwater quality data from DWAF's Water Management Systems (WMS) database. STATISTICA and ARCVIEW were used to process the data. The dental fluorosis data were obtained from a field study conducted by the Department of Health. The degree of dental ...

  20. Potential groundwater contamination by fluoride from two South ...

    African Journals Online (AJOL)

    A study to investigate the fluoride content in two South African phosphogypsums, Kynoch and Omnia, and the potential threat to water sources was undertaken. Kynoch and Omnia phosphogypsums were found to consist of fluoride in the region of 0.12% and 0.03% by mass, respectively. The phosphogypsum samples were ...

  1. Equilibrium Studies of Fluoride Adsorption onto a Ferric Poly ...

    African Journals Online (AJOL)

    Michael Horsfall

    2 CURRENT ADDRESS: Department of Chemistry, Bondo University College, P.O. Box 210 -40601, Bondo, Kenya. 3 Department of ... KEYWORDS: Adsorption isotherms; Equilibrium analysis; Ferric poly−mineral; Fluoride adsorption; Water fluoride .... rapid phase to a maximum of about 75% at 60 min. Similar trends could ...

  2. Fluoride Removal from Water by Reverse Osmosis Membrane

    Directory of Open Access Journals (Sweden)

    Sara Namavar

    2013-09-01

    Full Text Available As fluoride concentration in drinking water is one of the effective parameters in human health, finding the way to remove excess amount of fluoride from drinking water is very important in water supply projects. Today, with developing in technology and finding new methods, the use of membrane technology for producing fresh water get improved. In this study the efficiency of reverse osmosis method to remove fluoride from water was investigated. Initial concentration of fluoride, sulfate and electrical conductivity in feed water and the effect of associated cation with fluoride ion were studied. All tests adapted from “Standard Methods for Examination of Water and Wastewater”. Determination of fluoride concentration was done according the standard SPANDS method by using a spectrophotometer DR/5000. Obtain results show that with increasing in concentration of fluoride and sulfate and electrical conductivity in feed water the efficiency of RO membrane to remove fluoride reduced. In addition, this efficiency for CaF2 was higher than NaF.

  3. Equilibrium Studies of Fluoride Adsorption onto a Ferric Poly ...

    African Journals Online (AJOL)

    African countries along the Great Rift Valley are among areas of the world where excess fluoride in water sources is a major public health problem. In this work, the removal of fluoride (F) from water solutions using a ferric poly-mineral (FPM) from Kenya was therefore studied using batch adsorption experiments. The effect of ...

  4. Household water sources and their contribution towards fluoride ...

    African Journals Online (AJOL)

    Fluoride is regarded as an essential element for the formation of healthy bones and teeth. However, high fluoride levels in drinking water have been associated with high incidences of dental fluorosis. A 1996–1997 study in Njoro Division, Nakuru District, established that the groundwater used for cooking and drinking, ...

  5. Fluoride Analysis. Training Module 5.200.2.77.

    Science.gov (United States)

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with fluoride analysis procedures. Included are objectives, an instructor guide, student handouts, and a list of reference material. This module considers the determination of fluoride in water supplies using the SPANDS and electrode…

  6. Fluoride inhibits the response of bone cells to mechanical loading

    NARCIS (Netherlands)

    Willems, H.M.E.; van den Heuvel, E.G.H.M.; Castelein, S.; Buisman, J.K.; Bronckers, A.L.J.J.; Bakker, A.D.; Klein-Nulend, J.

    2011-01-01

    The response of bone cells to mechanical loading is mediated by the cytoskeleton. Since the bone anabolic agent fluoride disrupts the cytoskeleton, we investigated whether fluoride affects the response of bone cells to mechanical loading, and whether this is cytoskeleton mediated. The

  7. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Synthesis of mixed metal fluorides of the general formula, KMF3 (M = Mg, Mn, Co, Ni, Cu and. Zn), possessing perovskite structure was investigated in non-aqueous medium. The fluorides were characte- rized by powder X-ray diffraction, FT–IR spectroscopy, thermal analysis, SEM and TEM. Monophasic cubic.

  8. Mechanisms of action of fluoride for caries control

    NARCIS (Netherlands)

    Buzalaf, M.A.R.; Pessan, J.P.; Honório, H.M.; ten Cate, J.M.; Buzalaf, M.A.R.

    2011-01-01

    Fluoride was introduced into dentistry over 70 years ago, and it is now recognized as the main factor responsible for the dramatic decline in caries prevalence that has been observed worldwide. However, excessive fluoride intake during the period of tooth development can cause dental fluorosis. In

  9. comparative study of fluoride in alcornea cordifolia and commercial

    African Journals Online (AJOL)

    Quantum

    2013-07-31

    Jul 31, 2013 ... the analysis of cordifolia for fluoride and its percentage composition. ... Krook, 2006) and reduced intelligence in children (Li et al., 1995; Ziang et al., ... Qualitative analysis. Preliminary test for fluoride in A. cordifolia was carried out by drop- wise addition of concentrated sulphuric acid to the extract. An oily.

  10. BaFAlSi and BaFAlGe: First transition metal-free LaOAgS-type fluoride tetrelides

    Energy Technology Data Exchange (ETDEWEB)

    Charkin, Dmitri O., E-mail: charkin@inorg.chem.msu.ru; Plokhikh, Igor V.; Kuznetsov, Alexey N.; Kazakov, Sergey M.

    2015-04-05

    Highlights: • Two first tetrelide fluorides with the LaOAgS structure have been prepared. • They are also the first transition metal-free representatives of the structure type. • Contrary to pnictides, hydride tetrelides are predicted to have different structures. - Abstract: Studies of the LaOAgS-type compounds among alkaline earth – Al (Ga) fluoride tetrelides revealed the existence of two new compounds BaFAlSi and BaFAlGe which are the first representatives of fluoride tetrelides; they also are the first representatives of the structure type not involving transition metals. No compound of the structure type is formed for strontium and gallium. Quantum chemical calculations indicate that only these two compounds are thermodynamically stable; the structure is probably stabilized by ionic interactions in the FeSe-like anionic slabs, which are relatively weak for bonds formed between triels and tetrels that are close in electronegativity.

  11. Synthesis and characterization of binder-free Cr3C2 coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    International Nuclear Information System (INIS)

    Brupbacher, Michael C.; Zhang, Dajie; Buchta, William M.; Graybeal, Mark L.; Rhim, Yo-Rhin; Nagle, Dennis C.; Spicer, James B.

    2015-01-01

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr 3 C 2 , with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings

  12. Anti Streptococcus mutans non fluoride and fluoride containing sealants after adding nano-silver particles

    Directory of Open Access Journals (Sweden)

    Maryam Ghasempour

    2014-04-01

    Full Text Available   Background and Aims: Since recurrent caries are one of the major causes of failure in resin restorations, the production of antibacterial resin composites was always under investigation. The aim of this study was to evaluate the efficacy of fissure sealants containing nanosilver particles against the Streptococcus mutans.   Materials and Methods: In this experimental study, the antibacterial properties of two sealants (with fluoride (Clinpro 3M and without fluoride (Concise 3M was investigated with 0, 0.01, 0.02, 0.03, 0.04, 0.05% w/w after adding nano-silver using direct contact test. Sealants formed on the walls of 500ml micro tube and after curing, they left in contact with bacterial suspension. In periods of 3, 24, 48h, a 10 µl volume of liquid medium was placed in blood agar culture and after 24 h incubation at 37ºC, the number of S.mutans colony was counted by colony counter. Data were analyzed using ANOVA andT-test.   Results: Results reported sealants with fluoride comparing to non fluoride ones had significant effect on inhibition of S.mutans growth (P<0.001. The direct contact test demonstrated that by increasing the amount of nano particles, the bacterial growth was significantly diminished (P<0.001.   Conclusion: While sealants with fluoride demonstrated antibacterial effect, sealants with incorporation of higher weight percentage of nanosilver particles, had stronger and more significant antibacterial effect in direct contact test.

  13. Impurities in the [[sup 18]O]water target and their effect on the yield of an aromatic displacement reaction with [[sup 18]F]fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Schlyer, D.J.; Firouzbakht, M.L.; Wolf, A.P. (Brookhaven National Lab., Upton, NY (United States))

    1993-12-01

    Fluorine-18 in the form of fluoride ion has widespread utility in PET radiochemistry. This paper explores the effect of possible metal ion contamination of the water on the yield of the displacement of a nitro group of dinitrobenzene by fluoride has been investigated as a model reaction for fluoride displacement. The metal ions were found to have a profound effect if they were at the level of the carbonate added to the synthetic procedure. The yields from the reaction are best fit by a model in which the metal ions complex the carbonate ion and thus reduce the pH which in turn reduces the efficiency of the reaction. The formation of [[sup 18]F]fluoroacetate in the target was explored as a mode for making the fluoride in the target unreactive. It was found that essentially no fluoracetate was formed under our irradiation conditions. The sources of carrier fluoride were examined. It was found that carrier fluoride was introduced during the transfer of water into and out of the target and not during the irradiation. (Author).

  14. Electrorecovery of tantalum in molten fluorides

    International Nuclear Information System (INIS)

    Espinola, A.; Dutra, A.J.B.; Silva, F.T. da

    1988-01-01

    Considering the privileged situation of Brazil as a productor of tantaliferous minerals, the authors have in view the development of a technology for production of metallic tantalum via molten salts electrolysis; this has the advantage of improving the aggregate value of exportation products, additionally to tantalum oxide and tantalum concentrates. Having in view the preliminary determintion of better conditions of temperature, electrolyte composition and current density for this process, electrolysis were conducted with a solvent composed of an eutetic mixture of lithium, sodium and potassium fluoride for dipotassium fluotantalate and occasionally for tantalum oxide. Current efficiencies as high as 83% were obtained in favoured conditions. (author) [pt

  15. Scintillation of rare earth doped fluoride nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

    2011-09-12

    The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

  16. Prevention of dental caries through the effective use of fluoride

    DEFF Research Database (Denmark)

    Petersen, Poul Erik

    2016-01-01

    Background: The World Health Organization (WHO) emphasizes that dental caries is a severe public health problem across the world. The current global and regional patterns of dental caries reflect distinct risk profiles of countries which relate to the structure of the society, living conditions......, lifestyles, and the existence of preventive oral health programmes. Research conducted in high income countries documents that systematic use of fluoride reduces the burden of dental caries; such research is scarce in low and middle income countries. Objectives: This article reviews the evidence on effective...... use of fluoride, highlights the public health approach to fluoridation, and clarifies how automatic fluoridation contributes to breaking social inequities in dental caries. Data collection: Scientific publications on fluoride administration stored in PubMed/Medline and caries data from the WHO...

  17. The effective use of fluorides in public health

    DEFF Research Database (Denmark)

    Jones, Sheila; Burt, Brian A; Petersen, Poul Erik

    2005-01-01

    Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research and developm......Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research...... and their families, and the issue of cost. We recommend that a community should use no more than one systemic fluoride (i.e. water or salt or milk fluoridation) combined with the use of fluoride toothpastes, and that the prevalence of dental fluorosis should be monitored in order to detect increases in or higher...

  18. Fluoride use in Controlling Dental Caries and Fluorosis

    Directory of Open Access Journals (Sweden)

    Gaurav Solanki

    2012-07-01

    Full Text Available Policy were introduced to control fluoride exposure and to reduce the prevalence of fluorosis. The study aimed of describing the prevalence, severity and risk factors for fluorosis, and to describe the trend of fluorosis among Indian children. The study also aimed of exploring the effect of the change in fluoride exposure on dental fluorosis and caries. Establishing an appropriate use of fluoride toothpaste could be successful in reducing fluorosis without a significant increase in caries experience. The use of fluorides for oral health has always involved a balance between the protective benefit against dental caries and the risk of developing fluorosis. The link between fluoride and dental health was established to determining the causes of dental fluorosis or enamel mottling. Fluorosis in Indian children was highly prevalent in the early 1990s.

  19. Milk fluoridation for the prevention of dental caries

    Directory of Open Access Journals (Sweden)

    Jolán Bánóczy

    2013-11-01

    Full Text Available The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s – some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. Conclusion. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme.

  20. Relationship between enamel fluorosis severity and fluoride content.

    Science.gov (United States)

    Martinez-Mier, Esperanza A; Shone, Devin B; Buckley, Christine M; Ando, Masatoshi; Lippert, Frank; Soto-Rojas, Armando E

    2016-03-01

    Enamel fluorosis is a hypomineralization caused by chronic exposure to high levels of fluoride during tooth development. Previous research on the relationship between enamel fluoride content and fluorosis severity has been equivocal. The current study aimed at comparing visually and histologically assessed fluorosis severity with enamel fluoride content. Extracted teeth (n=112) were visually examined using the Thylstrup and Fejerskov Index for fluorosis. Eruption status of each tooth was noted. Teeth were cut into 100 μm slices to assess histological changes with polarized light microscopy. Teeth were categorized as sound, mild, moderate, or severe fluorosis, visually and histologically. They were cut into squares (2 × 2 mm) for the determination of fluoride content (microbiopsy) at depths of 30, 60 and 90 μm from the external surface. Erupted teeth with severe fluorosis had significantly greater mean fluoride content at 30, 60 and 90 μm than sound teeth. Unerupted teeth with mild, moderate and severe fluorosis had significantly greater mean fluoride content than sound teeth at 30 μm; unerupted teeth with mild and severe fluorosis had significantly greater mean fluoride content than sound teeth at 60 μm, while only unerupted teeth severe fluorosis had significantly greater mean fluoride content than sound teeth at 90 μm. Both erupted and unerupted severely fluorosed teeth presented higher mean enamel fluoride content than sound teeth. Data on fluoride content in enamel will further our understanding of its biological characteristics which play a role in the management of hard tissue diseases and conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Are fluoride releasing dental materials clinically effective on caries control?

    Science.gov (United States)

    Cury, Jaime Aparecido; de Oliveira, Branca Heloisa; dos Santos, Ana Paula Pires; Tenuta, Livia Maria Andaló

    2016-03-01

    (1) To describe caries lesions development and the role of fluoride in controlling disease progression; (2) to evaluate whether the use of fluoride-releasing pit and fissure sealants, bonding orthodontic agents and restorative materials, in comparison to a non-fluoride releasing material, reduces caries incidence in children or adults, and (3) to discuss how the anti-caries properties of these materials have been evaluated in vitro and in situ. The search was performed on the Cochrane Database of Systematic Reviews and on Medline via Pubmed. Caries is a biofilm-sugar dependent disease and as such it provokes progressive destruction of mineral structure of any dental surface - intact, sealed or restored - where biofilm remains accumulated and is regularly exposed to sugar. The mechanism of action of fluoride released from dental materials on caries is similar to that of fluoride found in dentifrices or other vehicles of fluoride delivery. Fluoride-releasing materials are unable to interfere with the formation of biofilm on dental surfaces adjacent to them or to inhibit acid production by dental biofilms. However, the fluoride released slows down the progression of caries lesions in tooth surfaces adjacent to dental materials. This effect has been clearly shown by in vitro and in situ studies but not in randomized clinical trials. The anti-caries effect of fluoride releasing materials is still not based on clinical evidence, and, in addition, it can be overwhelmed by fluoride delivered from dentifrices. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. High Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    Science.gov (United States)

    Weldesenbet, S. F.; Wohnlich, S.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS ( 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (surface system is simulated with sediment-packed column leached by flowing water and applying temporary interruption of flow during the experiment. The result indicated that a sharp increase of fluoride concentration (up to 58mg/kg) observed in leachates before one pore-volume of water eluted from the column. The concentration of leached fluoride consequently declined with the increased flowing pore-volume of water and finally the lowest concentrations of leached fluoride occurred in the end of the experiment. Flow interruption during column leaching experiment causes a noticeable fluoride concentration perturbation due to the heterogeneity of the sediment.

  3. Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    Science.gov (United States)

    Weldesenbet, S. F.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS ( 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (surface system is simulated with sediment-packed column leached by flowing water and applying temporary interruption of flow during the experiment. The result indicated that a sharp increase of fluoride concentration (up to 58mg/kg) observed in leachates before one pore-volume of water eluted from the column. The concentration of leached fluoride consequently declined with the increased flowing pore-volume of water and finally the lowest concentrations of leached fluoride occurred in the end of the experiment. Flow interruption during column leaching experiment causes a noticeable fluoride concentration perturbation due to the heterogeneity of the sediment.

  4. Two stable steady states in the Hodgkin-Huxley axons

    OpenAIRE

    Aihara, K.; Matsumoto, G.

    1983-01-01

    Two stable steady states were found in the numerical solution of the Hodgkin-Huxley equations for the intact squid axon bathed in potassium-rich sea water with an externally applied inward current. Under the conditions the two stable steady-states exist, the Hodgkin-Huxley equations have a complex bifurcation structure including, in addition to the two stable steady-states, a stable limit cycle, two unstable equilibrium points, and one asymptotically stable equilibrium point. It was also conc...

  5. Effect of Fluoride-containing Restorative Materials on Dentin Adhesion and Demineralization of Hard Tissues Adjacent to Restorations.

    Science.gov (United States)

    Almeida Ayres, Ana Paula; Tabchoury, Cínthia Pereira Machado; Bittencourt Berger, Sandrine; Yamauti, Monica; Bovi Ambrosano, Glaucia Maria; Giannini, Marcelo

    2015-08-01

    This study evaluated (1) the dentin bond strength of fluoridated restorative systems following aging and (2) the enamel/dentin microhardness around restorations after a pH-cycling regimen. Sixty-four human third molars and four restorative systems were used. A resin-modified glass ionomer (GC Fuji II LC) was used as a fluoride-containing material in the positive control group, while Adper Easy Bond adhesive and Filtek Z350 XT composite resin, which are not fluoridated, were used together in the negative control group. Beautifil II composite resin and FL-Bond II adhesive, both fluoride-containing materials, were compared to Bond Force and Estelite Sigma Quick restorative system, which only contain fluoride in the adhesive. For dentin bond strengths, specimens of each material were fabricated for two test groups (n=8): group 1: tested after 24 h; group 2: tested after 1 year of storage in artificial saliva. Both groups were tested using a microtensile method. For the cross-sectional microhardness test, standardized Class V cavities were prepared and filled with the different restorative systems. After experiencing repeated thermocycling and being subjected to pH-cycling, the teeth were sectioned. The microhardness was measured in enamel and dentin at 50 μm from the cavity wall and at six depths in relation to the surface subjected to pH cycling. None of the restorative systems showed decreased bond strength after storage for one year in artificial saliva. No significant differences in microhardness were observed among the restorative materials on enamel and dentin. All the restorative systems evaluated presented stable bond strength after one year of storage. The pH cycling caused a reduction in the superficial enamel microhardness close to the cavity wall. In dentin, the demineralization affected the superficial and sub-surface areas.

  6. Industrial Applications of Graphite Fluoride Fibers

    Science.gov (United States)

    Hung, Ching-Cheh; Kucera, Donald

    1991-01-01

    Based on fluorination technology developed during 1934 to 1959, and the fiber technology developed during the 1970s, a new process was developed to produce graphite fluoride fibers. In the process, pitch based graphitized carbon fibers are at first intercalated and deintercalated several times by bromine and iodine, followed by several cycles of nitrogen heating and fluorination at 350 to 370 C. Electrical, mechanical, and thermal properties of this fiber depend on the fluorination process and the fluorine content of the graphite fluoride product. However, these properties are between those of graphite and those of PTFE (Teflon). Therefore, it is considered to be a semiplastic. The physical properties suggest that this new material may have many new and unexplored applications. For example, it can be a thermally conductive electrical insulator. Its coefficient of thermal expansion (CTE) can be adjusted to match that of silicon, and therefore, it can be a heat sinking printed circuit board which is CTE compatible with silicon. Using these fibers in printed circuit boards may provide improved electrical performance and reliability of the electronics on the board over existing designs. Also, since it releases fluorine at 300 C or higher, it can be used as a material to store fluorine and to conduct fluorination. This application may simplify the fluorination process and reduce the risk of handling fluorine.

  7. Correlation among fluoride and metals in irrigation water and soils of ...

    African Journals Online (AJOL)

    Correlation among fluoride and metals in irrigation water and soils of Ethiopian Rift Valley. ... The fluoride concentrations in water samples were found in the range of 0.14-8.0 mg/L which is below the WHO limit of fluoride concentration for irrigation (less than 10 mg/L). ... KEY WORDS: Fluoride, Metals, Water, Soil, Ethiopia.

  8. Carbide Coatings for Nickel Alloys, Graphite and Carbon/Carbon Composites to be used in Fluoride Salt Valves

    Energy Technology Data Exchange (ETDEWEB)

    Nagle, Denis [Johns Hopkins Univ., Baltimore, MD (United States); Zhang, Dajie [Johns Hopkins Univ., Baltimore, MD (United States)

    2015-10-22

    The focus of this research was concerned with developing materials technology that supports the evolution of Generation IV Advanced High Temperature Reactor (AHTR) concepts. Specifically, we investigate refractory carbide coatings for 1) nickel alloys, and 2) commercial carbon-carbon composites (CCCs). Numerous compelling reasons have driven us to focus on carbon and carbide materials. First, unlike metals, the strength and modulus of CCCs increase with rising temperature. Secondly, graphite and carbon composites have been proven effective for resisting highly corrosive fluoride melts such as molten cryolite [Na₃AlF₆] at ~1000°C in aluminum reduction cells. Thirdly, graphite and carbide materials exhibit extraordinary radiation damage tolerance and stability up to 2000°C. Finally, carbides are thermodynamically more stable in liquid fluoride salt than the corresponding metals (i.e. Cr and Zr) found in nickel based alloys.

  9. Kinetic stable Cr isotopic fractionation between aqueous Cr(III)-Cl-H2O complexes at 25 °C: Implications for Cr(III) mobility and isotopic variations in modern and ancient natural systems

    Science.gov (United States)

    Babechuk, Michael G.; Kleinhanns, Ilka C.; Reitter, Elmar; Schoenberg, Ronny

    2018-02-01

    dissolution of two Cr(III)-Cl solids (dried NIST SRM979 standard and commercial CrCl3·6H2O salt) in 0.01 M HCl (pH ≈ 2). The ε53/52Cr(CrCl2+/CrCl2+) for the CrCl2+ to CrCl2+ reaction is -0.19‰ (SRM979) and -0.38‰ (salt) and the ε53/52Cr(Cr3+/CrCl2+) for the CrCl2+ to Cr3+ reaction is consistent for both experiments at -0.49‰ (SRM979) and -0.51‰ (salt). Experiments where SRM979 is dissolved in 0.1 and 1 M HCl for a longer aging period provide preliminary evidence that the Cr3+/CrCl2+ Cr(III) isotopic fractionation scales with HCl concentration (transformation rate). Chromium(III) dissolved in 6 M HCl and aged 5 months still yields an inter-species Cr isotope distribution that is apparently inherited from kinetic effects (light Cr isotopes in Cr3+), attesting to the slow development of inter-species isotopic equilibrium, which instead predicts progressively heavier Cr isotopes from CrCl2+ to CrCl2+ to Cr3+. The kinetic Cr(III) isotopic fractionation documented herein is proposed to be relevant to understanding systems where aqueous Cr(III)-Cl species may be temporarily stable (e.g., metamorphic and hydrothermal systems or lateritic weathering). Further, the complexation of Cr(III) with other ligands (e.g., CO32-, organics), combined with additional kinetic effects of Cr(III) potentially occurring in soils or sediment, must be explored prior to establishing the significance of empirical stable Cr isotope signatures in marine and continental environments. Further understanding of non-redox effects may lead to stable Cr isotopes developing as a proxy for system pH or ligand chemistry.

  10. FLUORIDE SORPTION USING MORRINGA INDICA-BASED ACTIVATED CARBON

    Directory of Open Access Journals (Sweden)

    G. Karthikeyan, S. Siva Ilango

    2007-01-01

    Full Text Available Batch adsorption experiments using activated carbon prepared from Morringa Indica bark were conducted to remove fluoride from aqueous solution. A minimum contact time of 25 min was required for optimum fluoride removal. The influence of adsorbent, dose, pH, co-ions (cations and anions on fluoride removal by the activated carbon has been experimentally verified. The adsorption of fluoride was studied at 30 C, 40 C and 50 C. The kinetics of adsorption and adsorption isotherms at different temperatures were studied. The fluoride adsorption obeyed both Langmuir and Freundlich isotherms and followed a pseudo first order kinetic model. The thermodynamic studies revealed that the fluoride adsorption by Morringa Indica is an endothermic process indicating an increase in sorption rate at higher temperatures. The negative values of G indicate the spontaneity of adsorption. SEM and XRD studies confirmed the surface morphological characteristics of the adsorbent and the deposition of fluoride on the surface of the material.

  11. Solubility and fluoride release in ionomers and compomers.

    Science.gov (United States)

    Bertacchini, S M; Abate, P F; Blank, A; Baglieto, M F; Macchi, R L

    1999-03-01

    The degree of solubility and the fluoride release of glass-ionomer cements and "compomers" were determined as a function of time. Three conventional glass-ionomer cements, three hybrid ionomers, and two compomers were included in the study. Disk-shaped specimens were prepared and immersed in a lactic acid solution. Solubility was evaluated from determinations of loss of mass as a function of time. To evaluate fluoride release, similar specimens were immersed in 50 mL of deionized water to which 50 mL of buffer solution was added. A fluoride ion detector was used to read the concentration of fluoride ion in the overall solution at different times after immersion. Material and time factors had a significant influence on results. The compomers showed less corrosion and fluoride release than the ionomers. Some correlation was found between solubility and fluoride leakage values. Components of both the ionomers and compomers that were studied can dissolve in water. The materials leak fluoride ions in amounts that differ according to the characteristics of the individual products.

  12. Statistical modeling of global geogenic fluoride contamination in groundwaters.

    Science.gov (United States)

    Amini, Manouchehr; Mueller, Kim; Abbaspour, Karim C; Rosenberg, Thomas; Afyuni, Majid; Møller, Klaus N; Sarr, Mamadou; Johnson, C Annette

    2008-05-15

    The use of groundwater with high fluoride concentrations poses a health threat to millions of people around the world. This study aims at providing a global overview of potentially fluoride-rich groundwaters by modeling fluoride concentration. A large database of worldwide fluoride concentrations as well as available information on related environmental factors such as soil properties, geological settings, and climatic and topographical information on a global scale have all been used in the model. The modeling approach combines geochemical knowledge with statistical methods to devise a rule-based statistical procedure, which divides the world into 8 different "process regions". For each region a separate predictive model was constructed. The end result is a global probability map of fluoride concentration in the groundwater. Comparisons of the modeled and measured data indicate that 60-70% of the fluoride variation could be explained by the models in six process regions, while in two process regions only 30% of the variation in the measured data was explained. Furthermore, the global probability map corresponded well with fluorotic areas described in the international literature. Although the probability map should not replace fluoride testing, it can give a first indication of possible contamination and thus may support the planning process of new drinking water projects.

  13. Protection From Dental Erosion: All Fluorides are Not Equal.

    Science.gov (United States)

    Faller, Robert V; Noble, Warden H

    2018-03-01

    All fluoride sources help strengthen teeth against bacterial acids that cause caries. However, excessive exposure to dietary acids, which can result in dental erosion, presents a more aggressive level of challenge compared to caries. Despite the fact that almost all toothpastes contain fluoride, both the incidence and prevalence of dental erosion appear to be on the rise. This article: (1) describes key differences between caries and dental erosion and the ability of different fluoride sources to help prevent erosion; (2) discusses the importance of the evaluation of patients for dental erosion at the earliest stages using the Basic Erosive Wear Examination scoring system to help assess and educate patients; and (3) provides evidence-based information for making specific recommendations to patients with dental erosion. The objective of this article is to assess the comparative ability of fluoride agents to protect against dental erosion. Though all fluorides are able to help strengthen teeth against cariogenic acids, not all available sources of fluoride provide the same level of erosion protection. Daily use of a stabilized stannous fluoride dentifrice has been shown to provide the most effective means of protecting teeth against the increasing risk of dental erosion and erosive tooth wear.

  14. Fluoride intake of children: considerations for dental caries and dental fluorosis.

    Science.gov (United States)

    Buzalaf, Marília Afonso Rabelo; Levy, Steven Marc

    2011-01-01

    Caries incidence and prevalence have decreased significantly over the last few decades due to the widespread use of fluoride. However, an increase in the prevalence of dental fluorosis has been reported simultaneously in both fluoridated and non-fluoridated communities. Dental fluorosis occurs due to excessive fluoride intake during the critical period of tooth development. For the permanent maxillary central incisors, the window of maximum susceptibility to the occurrence of fluorosis is the first 3 years of life. Thus, during this time, a close monitoring of fluoride intake must be accomplished in order to avoid dental fluorosis. This review describes the main sources of fluoride intake that have been identified: fluoridated drinking water, fluoride toothpaste, dietary fluoride supplements and infant formulas. Recommendations on how to avoid excessive fluoride intake from these sources are also given. Copyright © 2011 S. Karger AG, Basel.

  15. Water fluoridation and the quality of information available online.

    Science.gov (United States)

    Frangos, Zachary; Steffens, Maryke; Leask, Julie

    2018-02-13

    The Internet has transformed the way in which people approach their health care, with online resources becoming a primary source of health information. Little work has assessed the quality of online information regarding community water fluoridation. This study sought to assess the information available to individuals searching online for information, with emphasis on the credibility and quality of websites. We identified the top 10 web pages returned from different search engines, using common fluoridation search terms (identified in Google Trends). Web pages were scored using a credibility, quality and health literacy tool based on Global Advisory Committee on Vaccine Safety (GAVCS) and Center for Disease Control and Prevention (CDC) criteria. Scores were compared according to their fluoridation stance and domain type, then ranked by quality. The functionality of the scoring tool was analysed via a Bland-Altman plot of inter-rater reliability. Five-hundred web pages were returned, of which 55 were scored following removal of duplicates and irrelevant pages. Of these, 28 (51%) were pro-fluoridation, 16 (29%) were neutral and 11 (20%) were anti-fluoridation. Pro, neutral and anti-fluoridation pages scored well against health literacy standards (0.91, 0.90 and 0.81/1 respectively). Neutral and pro-fluoridation web pages showed strong credibility, with mean scores of 0.80 and 0.85 respectively, while anti-fluoridation scored 0.62/1. Most pages scored poorly for content quality, providing a moderate amount of superficial information. Those seeking online information regarding water fluoridation are faced with comprehensible, yet poorly referenced, superficial information. Sites were credible and user friendly; however, our results suggest that online resources need to focus on providing more transparent information with appropriate figures to consolidate the information. © 2018 FDI World Dental Federation.

  16. Amelioration of Fluoride Toxicity with the Use of Indigenous Inputs

    Directory of Open Access Journals (Sweden)

    Maitra A.

    2013-08-01

    Full Text Available An assessment was undertaken to study the efficacy of bacterial consortia isolated from different sources viz. rhizosphere of rice plant, oil spill sites of a petrol pump and from the sludge of a pharmaceutical waste water drain against the impact of fluoride. The experiments were conducted with two crops. In this mung bean experiment Vigna radiata was selected as a test crop. The seeds were sown in the field with bacterial consortia, compost and reduced dose (25% less nitrogen than recommended dose of chemical fertilizer. After 30days of seed sowing (DAS, plants were collected from the field and dipped into the sodium fluoride solution with different concentrations for 48 hours. Thereafter, the impact of fluoride on chlorophyll, sugar, proline and relative water content (% were evaluated. Scanning electron microscopy (SEM of the stem section was performed. SEM studies revealed that anatomical structure deformed with 1.5 mg/l sodium fluoride solution. It was observed that such treatment combination during the sowing of crops leads to combat the impact of lower doses of sodium fluoride (0.2 mg/l. Another experiment was also conducted within plastic pots with and without bacterial consortia isolated from rhizosphere of rice plant and oil spilled soil of petrol pump with the same field soil. Each pot was filled with 5 kg of soil + 2lt of water (on the basis of soil saturation. Oryza sativa seedlings were transplanted with different strength of sodium fluoride solution (25 mgNaF/kg, 50 mgNaF/kg, 100 mgNaF/kg and 500mgNaF/kg within the above pots. In second experiment, rice plants dried in all pots after 500 mgNaF/kg concentration of sodium fluoride. In this pot experiment bacterial strain are capable of reducing fluoride content in soil as noted by measuring fluoride in the pot soil after the experiment.

  17. Spectrophotometric determination of fluorides in water with Hach equipment

    International Nuclear Information System (INIS)

    Acosta L, E.

    1994-11-01

    The spectrophotometric method for the determination of the fluoride ion in water, demineralized water, raw waters, laundry waters and waters treated with ion exchange resins , using the technique and the SPADNS coloring indicated in the operation manual of the Hach equipment is described. This method covers the determination of the fluoride ion in the range from 0 to 2 mg/l on 25 ml. of radioactive base sample. These limits can be variable if the size of the used aliquot one is changed for the final determination of the fluoride ion. (Author)

  18. Nitrogen Trifluoride-Based Fluoride- Volatility Separations Process: Initial Studies

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, Bruce K.; Scheele, Randall D.; Casella, Andrew M.; Kozelisky, Anne E.

    2011-09-28

    This document describes the results of our investigations on the potential use of nitrogen trifluoride as the fluorinating and oxidizing agent in fluoride volatility-based used nuclear fuel reprocessing. The conceptual process uses differences in reaction temperatures between nitrogen trifluoride and fuel constituents that produce volatile fluorides to achieve separations and recover valuable constituents. We provide results from our thermodynamic evaluations, thermo-analytical experiments, kinetic models, and provide a preliminary process flowsheet. The evaluations found that nitrogen trifluoride can effectively produce volatile fluorides at different temperatures dependent on the fuel constituent.

  19. Sources of fluoride pollution in Kasur district, Pakistan

    International Nuclear Information System (INIS)

    Khan, I.H.; Haq, M.M.I.

    2005-01-01

    Serious bone problems were reported in certain localities in Pakistan due to contamination of drinking water by fluoride pollution. Against WHO recommended threshold limit of 0.7 mg/L, about 40 mg/L of fluoride is determined by ion chromatographic technique of HPLC. The compositions of pollutants were investigated in the present study by examination the chemical and mineralogical studies of water and soil samples. It is found that main problem in Manga Mandi area of District Kasur, was caused due to the decomposition of phosphorus containing minerals in soil under acidic conditions. The other sources of fluoride contamination in different areas of Pakistan is being investigated. (author)

  20. Determination of fluoride content in toothpaste using spectrophotometry

    Directory of Open Access Journals (Sweden)

    Susanti Pudji Hastuti

    2013-09-01

    Full Text Available Background: Intake excessive fluoride in children’s teeth are generally marked with white and brown patches. Excessive fluoride of more than 4.0 mg/L can cause a person suffering from poisoning, fragility of the bones (osteoporosis, liver and kidney damage. Knowledge about the spectrophotometry for determination method of fluoride content in commercially available toothpaste is very few. Purpose: The purposes of study were to examine the suitable method for fluoride extraction and to determine out the accuracy, precision, linearity, and stability of the measurement method of fluoride content in toothpaste. Methods: The suitable F extraction method was determined by the comparison among 3 methods of extraction; e.g. the dried samples were immersed in (1 distilled water, (2 96% HCl, and (3 96% HNO3; and the validation methods of measurement were the maximum wavelength, standart curve, accuracy test, precision test, and stability test. Results: Result showed that the fluoride extraction by using the concentrated HNO3 was found to have the highest levels of fluoride, followed by hydrochloric acid dissolution (HCl and distilled water, while the method of validation showed that SPADNS revealed the acceptable accuracy. Precision has the RSD ≤ 2.00%. Furthermore the stability test result showed that the measurement of fluoride less than 2 hours was still reliable. Conclusion: The study suggested that the best result of fluoride extraction from toothpaste could be gained by using concentrate HNO3, and the spectrophotometer (UV-Vis Mini Shimadzu U-1240 and SPADNS have the acceptable accuracy.Latar Belakang: Pemasukan fluoride yang berlebihan pada gigi anak ditandai dengan bercak putih dan coklat. Fluoride lebih dari 4.0 mg / L dapat menyebabkan seseorang menderita keracunan , kerapuhan tulang (osteoporosis, kerusakan hati dan ginjal. Pengetahuan tentang spektrofotometri untuk metode penentuan kadar fluoride dalam pasta gigi yang tersedia secara

  1. Effect of pH and fluoride on behavior of dental ZrO{sub 2} ceramics in artificial saliva

    Energy Technology Data Exchange (ETDEWEB)

    Mukaeda, L.E.; Robin, A.; Santos, C.; Taguchi, S.P.; Borges Junior, L.A., E-mail: luizamukaeda@gmail.com, E-mail: alain@demar.eel.usp.br, E-mail: claudinei@demar.eel.usp.br, E-mail: simone@demar.eel.usp.br, E-mail: borges.jr@itelefonica.com.br [Universidade de Sao Paulo (EEL/DEMAR/USP), Lorena, SP (Brazil). Escola de Engenharia; Machado, J.P.B., E-mail: joaopaulo@las.inpe.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    2009-07-01

    A considerable increase in the ceramic products demand occurred due to the evolution of dental restoration techniques and these materials must resist to the complex mouth environment. The pH of saliva can decrease significantly due to the ingestion of acidic foods and beverages and mainly due to reactions occurring during bacteria metabolism that lead to the formation of organic acids. Fluorides are also present in the mouth since fluorides are usually added in drinking water, mouth washes, tooth pastes and gels for the prevention of plaque and caries formation. The combination of low pH and presence of fluorides can lead to the formation of HF and HF{sub 2}{sup -} which are detrimental to metallic and probably to ceramic devices. In this work, commercial blocks of ZrO{sub 2} ceramics (ProtMat Materiais Avancados® and Ivoclar®) were immersed in Fusayama artificial saliva of different pHs and fluoride concentrations. The properties of the as-produced ceramics (crystalline phases (XRD), microstructure (SEM), roughness (3D surface topography AFM) and mechanical resistance - Vickers hardness (Hv) and fracture toughness (KIC) were evaluated. Some of these properties were also determined after the immersion tests as well as the mass variation of the samples in order to evaluate the resistance of these ZrO{sub 2} ceramics to degradation under these conditions. (author)

  2. Effect of pH and fluoride on behavior of dental ZrO2 ceramics in artificial saliva

    International Nuclear Information System (INIS)

    Mukaeda, L.E.; Robin, A.; Santos, C.; Taguchi, S.P.; Borges Junior, L.A.

    2009-01-01

    A considerable increase in the ceramic products demand occurred due to the evolution of dental restoration techniques and these materials must resist to the complex mouth environment. The pH of saliva can decrease significantly due to the ingestion of acidic foods and beverages and mainly due to reactions occurring during bacteria metabolism that lead to the formation of organic acids. Fluorides are also present in the mouth since fluorides are usually added in drinking water, mouth washes, tooth pastes and gels for the prevention of plaque and caries formation. The combination of low pH and presence of fluorides can lead to the formation of HF and HF 2 - which are detrimental to metallic and probably to ceramic devices. In this work, commercial blocks of ZrO 2 ceramics (ProtMat Materiais Avancados® and Ivoclar®) were immersed in Fusayama artificial saliva of different pHs and fluoride concentrations. The properties of the as-produced ceramics (crystalline phases (XRD), microstructure (SEM), roughness (3D surface topography AFM) and mechanical resistance - Vickers hardness (Hv) and fracture toughness (KIC) were evaluated. Some of these properties were also determined after the immersion tests as well as the mass variation of the samples in order to evaluate the resistance of these ZrO 2 ceramics to degradation under these conditions. (author)

  3. Fluoride Rinses, Gels and Foams: An Update of Controlled Clinical Trials.

    Science.gov (United States)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. Relevant papers were selected after an electronic search for literature published in English between 2003 and 2014. The included papers were assessed for their risk of bias and the results were narratively synthesized due to study heterogeneity. The quality of evidence was expressed according to GRADE. A total of 19 papers were included (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam, previously established in systematic reviews. The lack of clinical trials free from bias is, however, still a concern, especially for fluoride mouth rinses and fluoride foam. There is also a scientific knowledge gap on the benefit and optimal use of these fluoride supplements in combination with daily tooth brushing with fluoride toothpaste. © 2016 The Author(s) Published by S. Karger AG, Basel.

  4. Corrosion study in molten fluoride salt

    International Nuclear Information System (INIS)

    Keny, S.J.; Kumbhar, A.G.; Rangarajan, S.; Gupta, V.K.; Maheshwari, N.K.; Vijayan, P.K.

    2013-01-01

    Corrosion behaviors of two alloys viz. Inconel 625 and Inconel 617 were tested in molten fluoride salts of lithium, sodium and potassium (FLiNaK) in the temperature range of 550-750 ℃ in a nickel lined Inconel vessel. Electrochemical polarization (Tafel plot) technique was used for this purpose. For both alloys, the corrosion rate was found to increase sharply beyond 650 ℃ . At 600 ℃ , Inconel 625 showed a decreasing trend in the corrosion rate over a period of 24 hours, probably due to changes in the surface conditions. After fifteen days, re-testing of Inconel 625 in the same melt showed an increase in the corrosion rate. Inconel 625 was found to be more corrosion resistant than Inconel 617. (author)

  5. Electrocrystallisation of tantalum in molten fluoride media

    Energy Technology Data Exchange (ETDEWEB)

    Massot, L. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques et Materiaux, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex (France)]. E-mail: massot@chimie.ups-tlse.fr; Chamelot, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques et Materiaux, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex (France); Palau, P. [Pechiney CRV-UR GP, Parc Economique Centr' Alp, BP27, 38340 Voreppe (France); Taxil, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques et Materiaux, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex (France)

    2005-09-20

    The electrochemical nucleation of tantalum in molten alkaline fluoride media is investigated using chronoamperometry in the 670-750 deg C temperature range to optimize the operating conditions for preparing tantalum coatings for anode materials. Chronoamperometric results show that the electrodeposition process involves progressive nucleation with diffusion-controlled growth of the nuclei, which was confirmed by scanning electron microscopy. The influence of the temperature and the overpotential on the nucleation site densities is considered. Once the deposit has been obtained, plotting the roughness of the tantalum coatings as a function of the current densities reveals a minimum at about 80 mA/cm{sup 2}. This minimum is considered by the authors as a consequence of the progressive nucleation.

  6. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  7. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  8. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    IAS Admin

    After Maynard-Smith and Price [1] mathematically derived why a given behaviour or strategy was adopted by a certain proportion of the population at a given time, it was shown that a strategy which is currently stable in a population need not be stable in evolutionary time (across generations). Additionally it was sug-.

  9. [Incidence of caries in the Canton Waadt (Vaud) after the change from fluoride tablets to fluoridization of salt].

    Science.gov (United States)

    Marthaler, T M; Crousaz, P; Meyer, R; Regolati, B; Robert, A

    1975-01-01

    This report shows results of a survey on dental caries in the Canton of Vaud in the years 1970 and 1974. In this canton fluoridation was carried out by means of fluoride tablets distributed at school until 1969/70 and in subsequent years by adding 250 mg F/kg fluoride to domestic salt. For comparison, results from adjoining and other cantons are also presented. In 1970 the 3 communities in the Canton of Vaud (Moudon, Grandson and Vevey) showed a remarkably low overall caries level due to the distribution of fluoride tablets, supplemented in Grandson with regular brushings with fluoride solution. When the fluoride tablets were discontinued in 1968/70 and fluoridated domestic salt containing 250 mg F/kg NaCl was introduced, caries incidence reached an even lower level. In these 3 communities caries prevalence fell to the lowest level reached, so far, by means of preventive measures in Bettlach (Canton of Solothurn, toothbrushing with fluoride solutions 6 times per year combined with information, fluoride tablets on every school day, and in addition consumption of table salt fluoridated at a suboptimal level of 90 ppm). The children in the control communities Romont (Canton of Fribourg), St-Aubin (Canton of Neuchâtel) and Châtel-St-Denis (Canton of Fribourg) also showed decreases of caries levels from 1970 to 1974. This decrease can be attributed to the distribution of fluoride tablets started at the schools of this community in the late sixties. Caries incidence in the age spans 8 to 12 and 10 to 14 years was estimated. Children from the Canton of Vaud where fluoridated table salt was practically the only preventive measure showed a smaller DMF increase than those from the cantons Fribourg and Neuchâtel. By means of a method combining DMF means of various age groups it was possible to obtain sufficiently large numbers of children for a study of the caries prevalence in each community. All communities showed a decrease of caries levels. In the Canton of Vaud this

  10. Topical fluoride as a cause of dental fluorosis in children.

    Science.gov (United States)

    Wong, May Cm; Glenny, Anne-Marie; Tsang, Boyd Wk; Lo, Edward Cm; Worthington, Helen V; Marinho, Valeria Cc

    2010-01-20

    For many years, topical use of fluorides has gained greater popularity than systemic use of fluorides. A possible adverse effect associated with the use of topical fluoride is the development of dental fluorosis due to the ingestion of excessive fluoride by young children with developing teeth. To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis. Electronic search of the Cochrane Oral Health Group Trials Register, CENTRAL, MEDLINE, EMBASE, BIOSIS, Dissertation Abstracts and LILACS/BBO. Reference lists from relevant articles were searched. Date of the most recent searches: 9th March 09. Randomised controlled trials (RCTs), quasi-RCTs, cohort studies, case-control studies and cross-sectional surveys, in which fluoride toothpastes, mouthrinses, gels, foams, paint-on solutions, and varnishes were compared to an alternative fluoride treatment, placebo or no intervention group. Children under the age of 6 years at the time topical fluorides were used. Data from all included studies were extracted by two review authors. Risk ratios for controlled, prospective studies and odds ratios for case-control studies or cross-sectional surveys were extracted or calculated. Where both adjusted and unadjusted risk ratios or odds ratios were presented, the adjusted value was included in the meta-analysis. 25 studies were included: 2 RCTs, 1 cohort study, 6 case-control studies and 16 cross-sectional surveys. Only one RCT was judged to be at low risk of bias. The other RCT and all observational studies were judged to be at moderate to high risk of bias. Studies were included in four intervention/exposure comparisons. A statistically significant reduction in fluorosis was found if brushing of a child's teeth with fluoride toothpaste commenced after the age of 12 months odds ratio 0.70 (random-effects: 95% confidence interval 0.57 to 0.88) (data from observational studies). Inconsistent statistically significant

  11. Oral microflora in preschool children attending a fluoride varnish program

    DEFF Research Database (Denmark)

    Anderson, Maria; Grindefjord, Margaret; Dahllöf, Göran

    2016-01-01

    BACKGROUND: To compare the oral microflora in preschool children attending a fluoride varnish program with a reference group receiving a standard oral health program without fluoride varnish applications. A second aim was to relate the microbial composition to the caries prevalence. METHODS: Five...... hundred seven 3-year-old children were enrolled from a cohort of 3403 preschool children taking part in a community based oral health project. Two hundred sixty-three of them had attended caries-preventive program with semi-annual applications of a fluoride varnish since the age of 1 year (test group......-annual fluoride varnish applications did not seem to significantly influence the oral microflora in preschool children. TRIAL REGISTRATION: www.controlled-trials.com (ISRCTN35086887) 20131216 'retrospectively registered'....

  12. Water fluoridation for the prevention of dental caries.

    Science.gov (United States)

    Iheozor-Ejiofor, Zipporah; Worthington, Helen V; Walsh, Tanya; O'Malley, Lucy; Clarkson, Jan E; Macey, Richard; Alam, Rahul; Tugwell, Peter; Welch, Vivian; Glenny, Anne-Marie

    2015-06-18

    Dental caries is a major public health problem in most industrialised countries, affecting 60% to 90% of school children. Community water fluoridation was initiated in the USA in 1945 and is currently practised in about 25 countries around the world; health authorities consider it to be a key strategy for preventing dental caries. Given the continued interest in this topic from health professionals, policy makers and the public, it is important to update and maintain a systematic review that reflects contemporary evidence. To evaluate the effects of water fluoridation (artificial or natural) on the prevention of dental caries.To evaluate the effects of water fluoridation (artificial or natural) on dental fluorosis. We searched the following electronic databases: The Cochrane Oral Health Group's Trials Register (to 19 February 2015); The Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2015); MEDLINE via OVID (1946 to 19 February 2015); EMBASE via OVID (1980 to 19 February 2015); Proquest (to 19 February 2015); Web of Science Conference Proceedings (1990 to 19 February 2015); ZETOC Conference Proceedings (1993 to 19 February 2015). We searched the US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization's WHO International Clinical Trials Registry Platform for ongoing trials. There were no restrictions on language of publication or publication status in the searches of the electronic databases. For caries data, we included only prospective studies with a concurrent control that compared at least two populations - one receiving fluoridated water and the other non-fluoridated water - with outcome(s) evaluated at at least two points in time. For the assessment of fluorosis, we included any type of study design, with concurrent control, that compared populations exposed to different water fluoride concentrations. We included populations of all ages that received fluoridated water (naturally or artificially

  13. Ratiometric fluorescence signalling of fluoride ions by an ...

    Indian Academy of Sciences (India)

    Keywords. Chemosensor; ratiometric fluorescence signalling; fluoride ion; proton transfer; density functional calculation. ... Ravi Kumar Kanaparthi1 Anunay Samanta1. School of Chemistry, University of Hyderabad, Hyderabad 500 046; Training School, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 ...

  14. Readying Community Water Fluoridation Advocates through Training, Surveillance, and Empowerment.

    Science.gov (United States)

    Veschusio, C; Jones, M K; Mercer, J; Martin, A B

    2017-11-10

    This paper describes the Community Water Fluoridation Advocacy Training Project that was designed to develop networks of community water fluoridation advocates in rural communities. The South Carolina (SC) Department of Health and Environmental Control Division of Oral Health staff and the SC Dental Association were responsible for developing and facilitating the training sessions for key policy influencers, which included medical and dental providers, early childhood educators, and water system operators and managers. Findings from the post-training survey indicate that participants increased their knowledge and skills to discuss the impact of water fluoridation on the dental health of community residents. Participants identified a need for online access to water fluoridation education and advocacy materials. Dental public health competencies illustrated: communication and collaboration with groups and individuals, and advocate, implement and evaluate public health policy, legislation and regulations. Copyright© 2017 Dennis Barber Ltd.

  15. [Pharmacokinetic study of various fluoride compounds in rats].

    Science.gov (United States)

    Solymosi, G; Kertész, P; Ritlop, B; Bánóczy, J

    1992-02-01

    The fluoride excretion of 40 rats has been monitored after the consumption of drinking water containing NaF, CaF2 and CaF2 + alum (KRl/SO4/2. The fluoride excretion of the animals containing NaF and CaF2 + alum increased in a significant extent. No significant difference could be found in the fluoride excretion of the two groups. Statistically no significant increase has been observed in the fluoride ion excretion after the consumption of CaF2. These results suggest that by systemic intake of CaF2, no CaF2 absorbtion can be observed. So those undesirable gastric mucosa side effects that can be observed or presumed by the intake of NaF and CaF2 + alum are presumably neglibile.

  16. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing

    Indian Academy of Sciences (India)

    withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  17. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing ...

    Indian Academy of Sciences (India)

    withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  18. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Directory of Open Access Journals (Sweden)

    Timothy A. DeVol

    2010-03-01

    Full Text Available This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

  19. Chemical Emergency Preparedness and Prevention Advisory: Hydrogen Fluoride

    Science.gov (United States)

    This advisory recommends ways Local Emergency Planning Committees (LEPCs) and chemical facilities can reduce risks posed by the presence of hydrogen fluoride (HF), a strong inorganic acid used to manufacture CFCs, in their communities.

  20. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Science.gov (United States)

    Jacobsohn, Luiz G.; Kucera, Courtney J.; James, Tiffany L.; Sprinkle, Kevin B.; DiMaio, Jeffrey R.; Kokuoz, Baris; Yazgan-Kukouz, Basak; DeVol, Timothy A.; Ballato, John

    2010-01-01

    This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE) doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP) that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-)shell nanoparticles, and the CaF2-LaF3 system.

  1. Latest developments in non-fluoridated remineralizing technologies.

    Science.gov (United States)

    Goswami, M; Saha, S; Chaitra, T R

    2012-01-01

    The goal of modern dentistry is to manage non-cavitated carious lesions non-invasively through remineralization in an attempt to prevent disease progression, and to improve strength, esthetics, and function of teeth. The emphasis currently is being given to new technologies for enamel remineralization which suggest the changes in the understanding of dental caries. The aim of this paper is to review the contemporary non-fluoridated systems available for remineralization therapy and ideas for their implementation into clinical practice. A search of articles from "Pubmed" and "Medline" with the keywords Remineralization-demineralization, Casein derivatives, Non-fluoridated remineralizing agents was conducted. A total of 526 abstracts were collected, out of which 172 articles that discussed current technologies of non-fluoridated remineralizing agents were read and 33 most relevant articles were included in this paper. Casein phosphopeptide based technology has been established as a strong non-fluoridated remineralizing agent fulfilling all the criteria of an ideal remineralizing material.

  2. Theoretical study of H center in lithium fluoride

    International Nuclear Information System (INIS)

    Muniz, R.B.

    1977-03-01

    A phenomenological model for the electronic description of the H center in lithium fluoride is presented. Problems concerning the calculation of the hyperfine dipolar constants are also discussed, as well as ways to overcome them. (Author) [pt

  3. Preparation of rare earth fluorides from apatite concentrate

    International Nuclear Information System (INIS)

    Mulyarchuk, I.F.; Voloshchenko, M.V.; Zen'kovich, E.G.; Sumenkova, V.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Lit'ya)

    1980-01-01

    The processes of preparation of the rare earths element sum from apatite concentrate of the Khibins, connected with preliminary extraction of rare earth phosphates from nitric acid extract using solvent extraction or direct precipitation from the extract by solution of potassium and ammonium fluorides. The sequence of the processes of the first variant is the following: solvent extraction of rare earths by tributylphosphate from clarified nitric acid extract of apatite with subsequent reextraction of rare earths with water and precipitation of rare earth phosphates from aqueous solution during neutralization by ammonia. In case of fluoride preparation from rare earth phosphate the main attention is paid to precipitation and filtration of fluorides. Technological scheme and cost price of industry for the production of 1800 t of rare earth trifluorides a year are calculated. When taking account of TBP losses according to its solubility the industry cost price is 1O times lower the modern cost of rare earth fluorides

  4. Performance of a tungsten–cerium fluoride sampling calorimeter in high-energy electron beam tests

    Energy Technology Data Exchange (ETDEWEB)

    Becker, R.; Bianchini, L.; Dissertori, G.; Djambazov, L.; Donega, M.; Lustermann, W.; Marini, A.C.; Nessi-Tedaldi, F. [Institut for Particle Physics, ETH Zurich (Switzerland); Pandolfi, F., E-mail: francesco.pandolfi@cern.ch [Institut for Particle Physics, ETH Zurich (Switzerland); Peruzzi, M.; Schönenberger, M. [Institut for Particle Physics, ETH Zurich (Switzerland); Cavallari, F.; Dafinei, I.; Diemoz, M.; Lope, C. Jorda; Meridiani, P.; Nuccetelli, M.; Paramatti, R.; Pellegrino, F. [INFN – Sezione di Roma (Italy); Micheli, F. [Dipartimento di Fisica “Sapienza”, Università di Roma e INFN – Sezione di Roma (Italy); and others

    2015-12-21

    A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a GEANT4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype's energy resolution.

  5. Performance of a Tungsten-Cerium Fluoride Sampling Calorimeter in High-Energy Electron Beam Tests

    CERN Document Server

    Becker, R.; Dissertori, G.; Djambazov, L.; Donega, M.; Lustermann, W.; Marini, A.C.; Nessi-Tedaldi, F.; Pandolfi, F.; Peruzzi, M.; Schönenberger, M.; Cavallari, F.; Dafinei, I.; Diemoz, M.; Lope, C. Jorda; Meridiani, P.; Nuccetelli, M.; Paramatti, R.; Pellegrino, F.; Micheli, F.; Organtini, G.; Rahatlou, S.; Soffi, L.; Brianza, L.; Govoni, P.; Martelli, A.; Tabarelli de Fatis, T.; Monti, V.; Pastrone, N.; Trapani, P.P.; Candelise, V.; Della Ricca, G.

    2015-12-21

    A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype's energy resolution.

  6. Contribution to the study of fluoride dosing by using a membrane selective electrode

    International Nuclear Information System (INIS)

    Rivas, Jean de

    1972-01-01

    As the method of dosing fluoride ions by precipitation with lead fluorochloride is not very satisfying, the author reports the study of a new process for the dosing of the fluorine ion by using a selective electrode. After some generalities on selective electrodes (principle, types, operation principle) and some recalls and definitions (Galvani and Volta potential, stability constants of complexes, principles of diffusion in solids), the author reports the study of the diffusion potential in glass membranes, the study of the membrane potential, and the study of the ion exchange equilibrium. He presents methods of calculation of selectivity coefficients of membrane electrodes, and the reports experiments performed in laboratory

  7. Chitosan microparticles for the controlled delivery of fluoride.

    Science.gov (United States)

    Keegan, Gemma M; Smart, John D; Ingram, Matthew J; Barnes, Lara-Marie; Burnett, Gary R; Rees, Gareth D

    2012-03-01

    To manufacture and characterise chitosan/fluoride microparticles prepared by spray drying and assess their utility as controlled release vehicles for fluoride. Microparticles were manufactured from dispersions containing 1.0% and 2.0% (w/v) chitosan and 0.20% or 0.40% (w/v) NaF in the absence/presence of glutaraldehyde. Particle size distributions were determined using laser diffraction; fluoride loading and release were determined by ion-selective electrode. Release profiles were studied in isotonic media (pH 5.5) over 360 min; microparticles exhibiting greatest cumulative fluoride release were further evaluated at pH 4.0 and 7.0. Particle morphology was investigated using environmental scanning electron microscopy. Bioadhesion parameters were determined with a texture-probe analyser. Microparticles exhibited low polydispersity and volume mean diameters (VMDs) <6 μm. VMDs increased on doubling the chitosan/fluoride concentrations but were largely independent of glutaraldehyde concentration. Recovered yields were inversely proportional to dispersion viscosity due to compromised fluid atomisation; adding NaF reduced viscosity and improved yields. Best-case entrapment efficiency and NaF loading were 84.1% and 14%, respectively. Release profiles were biphasic, releasing 40-60% of the total fluoride during the first 600 s, followed by a prolonged release phase extending out to 6h. Incorporation of 0.40% NaF to the 2.0% chitosan dispersion yielded microparticles with reduced bioadhesive parameters (F(max) and WOA) versus the chitosan-only control whilst retaining significant bioadhesive potential. Bioadhesive chitosan/fluoride microparticles manufactured using a spray-drying protocol have been extensively characterised and further opportunity for optimisation identified. These microparticles may provide a means of increasing fluoride uptake from oral care products to provide increased protection against caries, however further work is required to demonstrate this

  8. New insight from noble gas and stable isotopes of geothermal/hydrothermal fluids at Caviahue-Copahue Volcanic Complex: Boiling steam separation and water-rock interaction at shallow depth

    Science.gov (United States)

    Roulleau, Emilie; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; Vinet, Nicolas; Bravo, Francisco; Muñoz, Carlos; Sanchez, Juan

    2016-12-01

    We measured noble gas and stable isotopes of the geothermal and hydrothermal fluids of the Caviahue-Copahue Volcanic Complex (CCVC), one of the most important geothermal systems in Argentina/Chile, in order to provide new insights into fluid circulation and origin. With the exception of Anfiteatro and Chancho-co geothermal systems, mantle-derived helium dominates in the CCVC fluids, with measured 3He/4He ratios up to 7.86Ra in 2015. Their positive δ15N is an evidence for subducted sediment-derived nitrogen, which is commonly observed in subduction settings. Both He-N2-Ar composition and positive correlation between δD-H2O and δ18O-H2O suggest that the fluids from Anfiteatro and Chancho-co (and partly from Pucon-Mahuida as well, on the southern flank of Copahue volcano) represent a meteoric water composition with a minor magmatic contribution. The Ne, Kr and Xe isotopic compositions are entirely of atmospheric origin, but processes of boiling and steam separation have led to fractionation of their elemental abundances. We modeled the CCVC fluid evolution using Rayleigh distillation curves, considering an initial air saturated geothermal water (ASGW) end-member at 250 and 300 °C, followed by boiling and steam separation at lower temperatures (from 200 °C to 150 °C). Between 2014 and 2015, the CCVC hydrogen and oxygen isotopes shifted from local meteoric water-dominated to andesitic water-dominated signature. This shift is associated with an increase of δ13C values and Stotal, HCl and He contents. These characteristics are consistent with a change in the gas ascent pathway between 2014 and 2015, which in turn induced higher magmatic-hydrothermal contribution in the fluid signature. The composition of the magmatic source of the CCVC fluids is: 3He/4He = 7.7Ra, δ15N = + 6‰, and δ13C = - 6.5‰. Mixing models between air-corrected He and N suggest the involvement of 0.5% to 5% of subducted sediments in the magmatic source. The magmatic sulfur isotopic

  9. Using a combination of radiogenic and stable isotopes coupled with hydrogeochemistry, limnometrics and meteorological data in hydrological research of complex underground mine-pit lake systems: The case of Cueva de la Mora

    Science.gov (United States)

    Sánchez-España, J.; Diez Ercilla, M.; Pérez Cerdán, F.; Yusta, I.

    2012-04-01

    This study presents a combination of radiogenic and stable isotopes (3H, 2H and 18O on pit lake water, and 34S on dissolved sulfate) coupled with bathymetric, meteorological and limnometric investigations, and detailed hydrogeochemical studies to decipher the flooding history and hydrological dynamics of a meromictic and deeply stratified pit lake in SW Spain. The application of these combined techniques has been specially succesful considering the complexity of the studied system, which includes a substantial number of horizontal galleries, shafts and large rooms physically connected to the pit lake. Specific conductance and temperature profiles have depicted a physical structure of the water body which includes four monimolimnetic layers of increasing density with depth. This internal configuration includes m-scale layers separated by sharp transional zones and is rarely observed in natural, fresh water bodies and most other pit lakes. The tritium abundance of the different layers indicate that the deepest water consists in strongly acidified and metal-laden meteoric water infiltrated in the mine system soon after the mine closure in 1971-72. Oxygen and hydrogen isotope ratios of the different layers reflect a sharp stratification with increasing evaporative influence towards the lake surface. The combination of tritium data with the oxygen and hydrogen isotope composition of the different layers suggests a model of pit lake formation with an initial stage of flooding (with entrance of highly metal- and sulfate-loaded mine drainage from the underlying mine galleries) that deeply determined the physical structure and meromictic nature of the lake. After reaching the present water level and morphology, the stagnant, anoxic part of pit lake seems to have remained chemically and isotopically unmodified during its 40 year-old history. Although the pit lake receives significant water input during autumn and winter (which in turn provoke significant volumetric increases

  10. SITUATION OF FLUORIDES RATE IN WATERS AND MAJOR ...

    African Journals Online (AJOL)

    31 déc. 2010 ... by fluoride ions in the waters of the region (Fluorosis Dental and skeletal). This study proposes, the estimated daily intake of fluoride from its water .... Le fluor est dosé par la méthode potentiométrique (NF T 90-004) grâce à une électrode spécifique aux ions fluorures. La mesure du potentiel a été effectuée ...

  11. Electrochemistry of silicon in chloro-fluoride and carbonate melts

    Directory of Open Access Journals (Sweden)

    Devyatkin S.V.

    2003-01-01

    Full Text Available The electrochemical behavior of K2SiF6 in chloro-fluoride melts and that of SiO2 in carbonate melts has been studied. Silicon, titanium silicides, boron silicide and ternary compounds Ti-Si-B have been deposited from chloro-fluoride melts. Only SiC was deposited from carbonate-silica melts under carbon dioxide atmosphere (that is, excessive pressure of CO2.

  12. Fluoride levels in commercial dentifrices and drinking Water in Algeria

    OpenAIRE

    MERGHACHE, D.; BELLOUT, B.; MERGHACHE, S.; BOUCHERIT-ATMANI, Z.

    2011-01-01

    More and more scientific evidence show that fluorides have a cariostatic action to the plaque-saliva-tooth interface during cariogenous dissolution. Fluorides slow down demineralization and enhance remineralization. Their action is optimal, in the oral environment, when used at low concentrations on a continuous basis. The use of the fluorinated toothpastes during brushing of the teeth is a simple, rational method of daily topics application of fluorine, largely used in the context of prevent...

  13. Estimation of Toothpaste Fluoride Intake in Preschool Children

    OpenAIRE

    Nascimento, Helena Aguiar Ribeiro do; Ferreira, Jainara Maria Soares; Granville-Garcia, Ana Flávia; Costa, Edja Maria Melo de Brito; Cavalcante, Ana Lúcia Almeida; Sampaio, Fábio Correia

    2013-01-01

    The objective of this study was to estimate the intake of toothpaste fluoride used by children aged 2 to 6 years (n=87) treated at a hospital of a medium-sized city (Campina Grande, PB) in the Northeastern region of Brazil. Data regarding sociodemographic characteristics of families and children's toothbrushing were collected from questionnaire-based interviews with parents/guardians, and the amount of fluoride used during toothbrushing was estimated using a precision scale for assessment of ...

  14. Molten fluoride mixtures as possible fission reactor fuels

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, W.R.

    1978-01-01

    Molten mixtures of fluorides with UF/sub 4/ as a component have been used as combined fuel and primary heat transfer agent in experimental high-temperature reactors and have been proposed for use in breeders or converters of /sup 233/U from thorium. Such use places stringent and diverse demands upon the fluid fuel. A brief review of chemical behavior of molten fluorides is given to show some of their strengths and weaknesses for such service.

  15. Quality of our groundwater resources: Arsenic and fluoride

    Science.gov (United States)

    Nordstrom, D. Kirk

    2011-01-01

    Groundwater often contains arsenic or fluoride concentrations too high for drinking or cooking. These constituents, often naturally occurring, are not easy to remove. The right combination of natural or manmade conditions can lead to elevated arsenic or fluoride which includes continental source rocks, high alkalinity and pH, reducing conditions for arsenic, high phosphate, high temperature and high silica. Agencies responsible for safe drinking water should be aware of these conditions, be prepared to monitor, and treat if necessary.

  16. Fluoride concentration in dentine as a biomarker of fluoride intake in European roe deer (Capreolus capreolus) - an electron-microprobe study.

    Science.gov (United States)

    Richter, Heiko; Kierdorf, Uwe; Richards, Alan; Melcher, Frank; Kierdorf, Horst

    2011-08-01

    Fluoride concentration in dentine has been recommended as the best marker for the level of chronic fluoride intake and the most suitable indicator of an individual's total body burden of fluoride. We analysed fluoride concentrations in the dentine of cheek teeth of European roe deer from fluoride-polluted habitats to retrospectively assess the level of fluoride uptake into the tissue. Thereby, we tested the hypothesis of the existence of mechanisms that limit fluoride intake of individuals and fluoride exposure of forming dental hard tissues during the late foetal and early postnatal periods in the species. Using electron-microprobe analysis, fluoride profiles were obtained on sectioned P(4)s, M(1)s, and M(3)s from individuals exhibiting pronounced dental fluorosis. Fluoride concentrations were compared between early formed (peripheral) and late-formed (juxtapulpal) dentine both within single teeth and amongst the three different teeth studied. Peripheral dentine of the M(1), which is formed during the late foetal and early postnatal periods, exhibited markedly lower fluoride concentrations than juxtapulpal dentine of the same tooth and both, peripheral and juxtapulpal dentine of P(4) and M(3) that are formed post-weaning. Our study provides strong support for the hypothesis that in the European roe deer the prenatal and early postnatal (pre-weaning) stages of dental development are (largely) protected against exposure to excess fluoride. This is attributed to the operation of certain protective mechanisms during these periods. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Fluoride and aluminum in teas and tea-based beverages

    Directory of Open Access Journals (Sweden)

    Hayacibara Mitsue Fujimaki

    2004-01-01

    Full Text Available OBJECTIVE: To evaluate fluoride and aluminum concentration in herbal, black, ready-to-drink, and imported teas available in Brazil considering the risks fluoride and aluminum pose to oral and general health, respectively. METHODS: One-hundred and seventy-seven samples of herbal and black tea, 11 types of imported tea and 21 samples of ready-to-drink tea were divided into four groups: I-herbal tea; II-Brazilian black tea (Camellia sinensis; III-imported tea (Camellia sinensis; IV-ready-to-drink tea-based beverages. Fluoride and aluminum were analyzed using ion-selective electrode and atomic absorption, respectively. RESULTS: Fluoride and aluminum levels in herbal teas were very low, but high amounts were found in black and ready-to-drink teas. Aluminum found in all samples analyzed can be considered safe to general health. However, considering 0.07 mg F/kg/day as the upper limit of fluoride intake with regard to undesirable dental fluorosis, some teas exceed the daily intake limit for children. CONCLUSIONS: Brazilian and imported teas made from Camellia sinensis as well as some tea-based beverages are sources of significant amounts of fluoride, and their intake may increase the risk of developing dental fluorosis.

  18. Fluoride consumption and its impact on oral health.

    Science.gov (United States)

    Jiménez-Farfán, María Dolores; Hernández-Guerrero, Juan Carlos; Juárez-López, Lilia Adriana; Jacinto-Alemán, Luis Fernando; de la Fuente-Hernández, Javier

    2011-01-01

    The purpose of this study was to evaluate caries and dental fluorosis among Mexican preschoolers and school-aged children in a non-endemic zone for fluorosis and to measure its biological indicators. DMFT, DMFS, dmft, dmfs, and CDI indexes were applied. Fluoride urinary excretion and fluoride concentrations in home water, table salt, bottled water, bottled drinks, and toothpaste were determined. Schoolchildren presented fluorosis (CDI = 0.96) and dental caries (DMFT = 2.64 and DMFS = 3.97). Preschoolers presented dmft = 4.85 and dmfs = 8.80. DMFT and DMFS were lower in children with mild to moderate dental fluorosis (DF). Variable fluoride concentrations were found in the analyzed products (home water = 0.18-0.44 ppm F, table salt = 0-485 ppm F, bottled water = 0.18-0.47 ppm F, juices = 0.08-1.42 ppm F, nectars = 0.07-1.30 ppm F, bottled drinks = 0.10-1.70 ppm F, toothpaste = 0-2,053 ppm F). Mean daily fluoride excretion was 422 ± 176 μg/24 h for schoolchildren and 367 ± 150 μg/24 h for preschoolers. Data from our study show that, despite values of excretion within an optimal fluoride intake range, the prevalence of caries was significant in both groups, and 60% of the 11- to 12-year-old children presented with dental fluorosis. In addition, variable fluoride concentrations in products frequently consumed by children were found.

  19. Determination of Fluoride in Organic and Non-organic Wines.

    Science.gov (United States)

    Paz, Soraya; Jaudenes, Juan Ramón; Gutiérrez, Angel José; Rubio, Carmen; Hardisson, Arturo; Revert, Consuelo

    2017-07-01

    Fluorine is an element of great importance to human health, as it is considered to be an essential element. However, both a deficiency and an excess, it can cause various problems. It is for this reason that values have been established regarding the recommended daily intake (RDI) and acceptable daily intake (ADI). The largest source of incorporation of fluoride is water, but it can be found in other foods and beverages, such as vegetables, tea, and wine. The aim of the study was to establish the fluoride concentration in organic and non-organic wines from different appellations of origin of the Canary Islands and mainland Spain, in order to assess the contribution of fluoride and toxic risk. A total of 53 samples of red, white, and rosé wines, both organic and non-organic, from different appellations of origin were analyzed. They were analyzed by potentiometric determination with ion-selective electrode for fluoride using the method of standard addition. The wines analyzed are within the recommended limits set by the International Organisation of Vine and Wine. RDI is not exceeded for adults, taking into account the data provided by the Spanish Agency for Consumer Affairs, Food Safety and Nutrition on the average consumption of "table wines" in Spain. Fluoride intake from wine poses no risk to the health of adults. The fluoride concentration of organic and non-organic wines is within the range of 0.03 to 0.70 mg/L.

  20. Does fluoride in drinking water delay tooth eruption?

    Science.gov (United States)

    Jolaoso, Ismail Adeyemi; Kumar, Jayanth; Moss, Mark E

    2014-01-01

    The objectives of this study are to determine the effect of fluoride exposure on permanent tooth eruption patterns as well as to understand its effect on caries attack rate by accounting for the number of erupted tooth surfaces. We analyzed data from the 1986-1987 National Survey of Oral Health of US Schoolchildren to determine the mean number of erupted permanent teeth and permanent first molars according to fluoride level in drinking water. The analysis included 13,348 children aged 5-17 years with a history of single residence. We also estimated the attack rate (decayed, missing, and filled surfaces/surfaces at risk) for fluoride deficient, suboptimal, and optimally fluoridated areas adjusting for covariates. Multivariable statistical analyses were performed to control for potential confounders. By age 7, almost all permanent first molars had erupted. The adjusted mean number of erupted permanent first molars per child were 3.81, 3.67, and 3.92 in areas with erupted teeth. Exposure to fluoride in drinking water did not delay the eruption of permanent teeth. The observed difference in dental caries experience among children exposed to different fluoride levels could not be explained by the timing of eruption of permanent teeth. © 2014 American Association of Public Health Dentistry.

  1. Fluoride varnishes containing sodium trimetaphosphate reduce enamel demineralization in vitro.

    Science.gov (United States)

    Manarelli, Michele M; Delbem, Alberto C B; Báez-Quintero, Liliana Carolina; de Moraes, Felipe Ricardo N; Cunha, Robson F; Pessan, Juliano P

    2017-07-01

    This study evaluated the effects of fluoride varnishes containing sodium trimetaphosphate (TMP) on bovine enamel demineralization in vitro. Enamel bovine discs were randomly assigned into six groups (n = 20/group): placebo, 2.5% NaF, 2.5% NaF/5% TMP, 5% NaF, 5% NaF/5% TMP, and a commercial formulation (Duraphat, 5% NaF). Varnishes were applied on all enamel discs and kept for 6 h. Loosely and firmly bound fluoride formed on/in enamel after treatment were analyzed in 10 discs from each group. The other 10 discs were subjected to a pH-cycling regimen for 7 days, and analyzed for surface (SH) and cross-sectional hardness (ΔKHN), as well as for loosely and firmly bound fluoride in/on enamel. Data were analyzed by analysis of variance (ANOVA) followed by Student-Newman-Keuls' test (p fluoridated varnishes containing TMP promoted significantly lower SH change and ΔKHN when compared with their counterparts without TMP. Loosely and firmly bound fluoride was significantly lower in groups treated with varnishes containing TMP. TMP and fluoride added to varnishes have a synergistic effect against enamel demineralization in vitro.

  2. Risk assessment of fluoride exposure in drinking water of Tunisia.

    Science.gov (United States)

    Guissouma, Wiem; Hakami, Othman; Al-Rajab, Abdul Jabbar; Tarhouni, Jamila

    2017-06-01

    The presence of fluoride in drinking water is known to reduce dental cavities among consumers, but an excessive intake of this anion might leads to dental and skeletal fluorosis. This study reports a complete survey of the fluoridated tap water taken from 100 water consumption points in Tunisia. The fluoride concentrations in tap water were between 0 and 2.4 mg L -1 . Risk assessment of Fluoride exposure was assessed depending on the age of consumers using a four-step method: hazard identification, toxicity reference values selection (TRVs), daily exposure assessment, and risk characterization. Our findings suggest that approximately 75% of the Tunisian population is at risk for dental decay, 25% have a potential dental fluorosis risk, and 20% might have a skeletal fluorosis risk according to the limits of fluoride in drinking water recommended by WHO. More investigations are recommended to assess the exposure risk of fluoride in other sources of drinking water such as bottled water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Effect of fluoride addition on the properties of dental alginate impression materials.

    Science.gov (United States)

    Lee, Yong-Keun; Lim, Bum-Soon; Kim, Cheol-We

    2004-03-01

    Fluoride-containing dental alginate impression materials can exert a considerable reduction in enamel solubility. The objective was to evaluate the effects of fluoride addition in the alginate impression materials on the properties and subsequent release of fluoride. Four experimental alginate impression materials were studied. Materials were mixed with distilled water (control) or 100-ppm fluoride solution. One or two percent NaF, or 1% SnF2 was added to the materials, which were mixed with distilled water. Fluoride release, flexibility, recovery from deformation, setting time, compressive strength and elastic modulus were determined in accordance with the ISO 1563 and ANSI/ADA Spec. 18. Fluoride release increased after addition of fluoride, and the released amount was 0.762-14.761 ppm. Addition of NaF or SnF2 resulted in higher fluoride release than the control group (p alginate impression material may result in effective release of fluoride without deteriorating the properties of material itself.

  4. Normal modified stable processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Shephard, N.

    2002-01-01

    This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...... Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process...

  5. Applications of stable isotopes

    International Nuclear Information System (INIS)

    Letolle, R.; Mariotti, A.; Bariac, T.

    1991-06-01

    This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

  6. Structural study of chlorine tri-fluoride and bromine penta-fluoride in liquid and solid phase

    International Nuclear Information System (INIS)

    Rousson, R.

    1973-01-01

    This research thesis reports the structural study of chlorine tri-fluoride and bromine penta-fluoride between 20 C and about -265 C. After some generalities on these compounds and a presentation of the experimental technique, the author reports and discusses results obtained with these both compounds: Raman spectrum for the liquid and for the solid phase, infrared spectrum for the solid phase, calorimetric measurements. In the case of chlorine tri-fluoride, the author studies the evolution of the liquid spectrum with temperature, shows the existence of an intermediate solid phase, and compares results obtained by Raman spectroscopy and nuclear magnetic resonance. He also applies to bromine penta-fluoride an analysis of normal coordinates of a XF 5 molecule: relationship between force constants and vibration frequencies, application of Wilson method, resolution of the molecular equation, determination of normal vibration modes [fr

  7. Impact of geology and geomorphology on fluoride contaminated groundwater in hard rock terrain of India using geoinformatics approach

    Science.gov (United States)

    Shekhar, Shashank; Ghosh, Mili; Pandey, A. C.; Tirkey, Anamika Shalini

    2017-10-01

    The present study demonstrates a GIS-based spatial evaluation of fluoride contamination (FC) in groundwater vis-a-vis geology and geomorphology of the area using analytical hierarchy process and weighted sum method in Palamu district of Jharkhand. The integration and analyses of the various thematic databases along with the field sampled fluoride data proved useful in delineating the FC zones. The FC index ranged between 141 and 707, and was classified into four zones, viz., low, moderate, high, and very high zones of FC. The FC index map showed that a total of 49.75% of the study area lies between high to very high FC zone. The very high FC zone is found in the moderately weathered plateau with granitic terrain, whereas the high and moderately FC zones covering 49.31 and 36.41% of the study area are dominated by plateau weathered shallow, pediment-inselberg complex, pediplain moderately weathered, pediplain shallow weathered, and inselberg which have high fluoride. The lowest FC zone covers an area of 193.27 sq. km (13.84%). The spatial analysis of geology with fluoride showed that groundwater within granitic gneiss exhibits high FC followed by granitoid gneiss and alluvium. Geomorphologically highest FC was recorded in plateau weathered moderate (91.67%) followed by plateau weathered shallow (71.43%), flood plain (41.76%), inselberg (27.27%), and pediment (25%). The spatial analysis of groundwater yield with fluoride showed that regions having good yield exhibit maximum FC thereby accelerating the vulnerability of the population to fluorosis.

  8. Interactions of fluoride and guanine nucleotides with thyroid adenylate cyclase.

    Science.gov (United States)

    Goldhammer, A; Wolff, J

    1982-02-18

    The activation of bovine thyroid adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) by Gpp(NH)p has been studied using steady-state kinetic methods. This activation is complex and may be characterized by two Gpp(NH)p binding sites of different affinities with measured constants: Ka1 = 0.1 micro M and Ka2 = 2.9 micro M. GDP beta S does not completely inhibit the Gpp(NH)p activation: analysis of the data is consistent with a single GDP beta S inhibitory site which is competitive with the weaker Gpp(NH)p site. Guanine nucleotide effects upon F- activation of adenylate cyclase have been studied. When App(NH)p is the substrate, 10 micro M GTP along with 10 mM NaF gives higher activity than NaF alone, while GDP together with NaF inhibits the activity by 50% relative to NaF. These features are not observed when the complex is assayed with ATP in the presence of a nucleotide regenerating system or when analogs Gpp)NH)p or GDP beta S are used along with NaF. These effects were studied in three other membrane systems using App(NH)p as substrate: rat liver, rat ovary and turkey erythrocyte. No consistent pattern of guanine nucleotide effects upon fluoride activation could be observed in the different membrane preparations. Previous experiments showed that the size of soluble thyroid adenylate cyclase changed whether membranes were preincubated with Gpp(NH)p or NaF. This size change roughly corresponded to the molecular weight of the nucleotide regulatory protein. This finding, coupled with the present data, suggests that two guanine nucleotide binding sites may be involved in regulating thyroid cyclase and that these sites may be on different protein chains.

  9. Analysing Stable Time Series

    National Research Council Canada - National Science Library

    Adler, Robert

    1997-01-01

    We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...

  10. High Temperature Fluoride Salt Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, Adam M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cunningham, Richard Burns [Univ. of Tennessee, Knoxville, TN (United States); Fugate, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holcomb, David Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kisner, Roger A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peretz, Fred J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yoder, Jr, Graydon L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  11. Zirconium-carbon hybrid sorbent for removal of fluoride from water: oxalic acid mediated Zr(IV) assembly and adsorption mechanism.

    Science.gov (United States)

    Velazquez-Jimenez, Litza Halla; Hurt, Robert H; Matos, Juan; Rangel-Mendez, Jose Rene

    2014-01-21

    When activated carbon (AC) is modified with zirconium(IV) by impregnation or precipitation, the fluoride adsorption capacity is typically improved. There is significant potential to improve these hybrid sorbents by controlling the impregnation conditions, which determine the assembly and dispersion of the Zr phases on carbon surfaces. Here, commercial activated carbon was modified with Zr(IV) together with oxalic acid (OA) used to maximize the zirconium dispersion and enhance fluoride adsorption. Adsorption experiments were carried out at pH 7 and 25 °C with a fluoride concentration of 40 mg L(-1). The OA/Zr ratio was varied to determine the optimal conditions for subsequent fluoride adsorption. The data was analyzed using the Langmuir and Freundlich isotherm models. FTIR, XPS, and the surface charge distribution were performed to elucidate the adsorption mechanism. Potentiometric titrations showed that the modified activated carbon (ZrOx-AC) possesses positive charge at pH lower than 7, and FTIR analysis demonstrated that zirconium ions interact mainly with carboxylic groups on the activated carbon surfaces. Moreover, XPS analysis demonstrated that Zr(IV) interacts with oxalate ions, and the fluoride adsorption mechanism is likely to involve -OH(-) exchange from zirconyl oxalate complexes.

  12. Formation of Fluorohydroxyapatite with Silver Diamine Fluoride.

    Science.gov (United States)

    Mei, M L; Nudelman, F; Marzec, B; Walker, J M; Lo, E C M; Walls, A W; Chu, C H

    2017-09-01

    Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared-calcium phosphate (CaCl 2 ·2H 2 O + K 2 HPO 4 in buffer solution) and SDF (Ag[NH 3 ] 2 F in buffer solution). After incubation at 37 o C for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with

  13. Fluoride accumulation in soil and vegetation in the vicinity of brick fields.

    Science.gov (United States)

    Jha, S K; Nayak, A K; Sharma, Y K; Mishra, V K; Sharma, D K

    2008-04-01

    Fluoride in the soil and vegetation in the vicinity of brick field in the suburb of Lucknow, India was estimated. The water soluble fluoride (1:1) in the surface soil ranged from 0.59 ppm to 2.74 ppm where as CaCl(2) extractable fluoride ranged from 0.69 ppm to 3.18 ppm. The mean total fluoride concentration in surface soil varied from 322 microg g(-1) to 456 microg g(-1). The local vegetations grown in the area found to accumulate air borne fluoride from the brick field. The fluoride accumulation in the vegetation followed the order Mentha arvensis > Spinacea oleracea > Luffa cylindrical.

  14. The efficacy of amine fluoride/stannous fluoride in the suppression of morning breath odour.

    Science.gov (United States)

    Quirynen, Marc; Avontroodt, Pieter; Soers, Catherine; Zhao, Hong; Pauwels, Martine; Coucke, Wim; van Steenberghe, Daniel

    2002-10-01

    Breath odour is a complaint encountered worldwide, often linked to microbial overload in the oral cavity. This double blind, crossover, randomised study assessed the efficacy of several antiseptic mouthrinses or slurry vs. a control solution in the prevention of morning bad breath during an experimental period of 7 days without mechanical plaque control. Sixteen dental students with a healthy periodontium abolished, after a thorough professional cleaning, all means of mechanical plaque control during five experimental periods of 7 days, interleaved by washout periods of at least 3 weeks. During each experimental period, as the only oral hygiene measure, the students rinsed twice a day with one of the following formulations (in a randomised order): a 0.2% chlorhexidine-alcohol mouthrinse (CHX-Alc), a 0.05% CHX + 0.05% cetylpyridinium chloride + 0.14% zinc lactate mouthrinse (CHX-CPC-Zn), an amine fluoride/stannous fluoride (125 ppm F-/125 ppm F-) containing mouthrinse (AmF/SnF2Mr), a slurry of a tooth paste (AmF/SnF2Sl) containing amine fluoride (350 ppm F-) and stannous fluoride (1050 ppm F-) and a placebo solution (placebo). At days 0, 3 and 7, morning breath was scored via VSC level measurements of the mouth air, and organoleptic ratings of the mouth air and tongue coating. At the same visits both the degree of gingival inflammation and the de novo plaque formation were rated. At the end of each period a questionnaire for subjective ratings was completed and microbiological samples were taken from the tongue dorsum, the saliva and the supragingival plaque for anaerobic and aerobic culturing. Although oral hygiene during the experimental periods was limited to rinsing, bad breath parameters systematically improved (P or= 0.5 log reduction with a superiority (P plaque formation was significantly (P products. The CHX-Alc solution scored significantly worse for the subjective evaluation (questionnaires) concerning taste and sensitivity of tongue). The results of this

  15. Method to separate hydrogen fluoride from an uranium hexafluoride-hydrogen fluoride mixture

    International Nuclear Information System (INIS)

    Pfistermeister, M.; Jokar, J.

    1978-01-01

    It is difficult to separate off HF in the purification of UF 6 from additional compounds. According to the invention, it is possible without too greater effort to form the hardly volatile tri-(perfluorobutyl)-ammonium fluoride by adding a perfluorate amine or a derivate of it, and then to separate off the UF 6 from the adduct by simple distillation or sublimation. The adduct can be easily split again with NaOH, so that the amine can be used again without loss. (RW) [de

  16. Method to separate off hydrogen fluoride from a uranium hexafluoride-hydrogen fluoride mixture

    International Nuclear Information System (INIS)

    Pfistermeister, M.; Jokar, J.

    1979-01-01

    There have been sofar difficulties involved in separating off HF when purifying UF 6 . According to the invention, this can be achieved without great expenditure if one adds a perfluorated amine or derivative of it to the UF 6 -HF mixture. The UF 6 can be separated by simple distillation or sublimation from the hardly-volatile formed tri-(perfluoro-butyl) ammonium fluoride. The adduct formed can be easily split again with NaOH so that the amine can be recycled without loss. (UWI) [de

  17. Effect of sodium fluoride on bone density in chickens.

    Science.gov (United States)

    Lundy, M W; Russell, J E; Avery, J; Wergedal, J E; Baylink, D J

    1992-05-01

    In addition to increasing bone volume, fluoride has been demonstrated to increase ash weight and mineral density. To determine whether newly formed or older bone is most affected by fluoride treatment, bone from chickens receiving fluoridated water was fractionated into lower density (recently formed) and higher density (more mature) specific gravity fractions. Fluoride was administered to the chickens for different lengths of time (4 or 13 weeks) or at varying doses for a 4-week period (0, 4.2, 16.8 mmol/liter drinking water). Fluoride treatment caused a shift in the mineral density profile, showing an increased proportion of mineral distribution in the more mature, higher density fractions. To determine whether this density gradient shift was due to increased maturation rate of bone or decreased resorption and mineralization rates, [3H]proline and 45Ca were injected 5 days and 24 hours prior to sacrifice, respectively. The distributions of both 3H or 45Ca, as percentages of total counts incorporated, were shifted by fluoride treatment into more mature, higher density fractions. Expressing the number of counts as a percent of the bone in each fraction (total hydroxyproline or Ca) revealed an increased incorporation of both 3H and 45Ca into the higher specific gravity fractions 2.0-2.2. These results suggest that fluoride treatment increases bone maturation and the rate of secondary mineralization in the cortical bone. Such changes in the quality of more mature, well-mineralized bone, in humans as well as animals, may have a significant influence on brittleness and strength.

  18. Profile of Fluoride Release from a Nanohybrid Composite Resin

    Directory of Open Access Journals (Sweden)

    Raquel Assed Bezerra Silva

    2015-02-01

    Full Text Available The aim of this study was to evaluate in vitro the amount and profile of fluoride release from a fluoride-containing nanohybrid composite resin (Tetric® N-Ceram by direct potentiometry. Thirty specimens (5 mm diameter x 3 mm high; n=10/material were made of Tetric® N-Ceram, Vitremer® resin-modified glass ionomer cement (RMGIC (positive control or Filtek® Z350 nanofill composite resin (negative control. The specimens were stored individually in plastic tubes containing 1 mL of artificial saliva at 37°C, which was daily renewed during 15 days. At each renewal of saliva, the amount of fluoride ions released in the solution was measured using a fluoride ion-selective electrode with ion analyzer, and the values obtained in mV were converted to ppm (µg/mL. Data were analyzed statistically by ANOVA and Tukey’s post-hoc test at a significance level of 5%. The results showed that the resins Tetric® N-Ceram and Filtek® Z350 did not release significant amounts of fluoride during the whole period of evaluation (p>0.05. Only Vitremer® released significant amounts of fluoride ions during the 15 days of the experiment, with greater release in first 2 days (p0.05. In conclusion, the nanohybrid composite resin Tetric® N-Ceram did not present in vitro fluoride-releasing capacity throughout the 15 days of study.

  19. Fluoride potentiates tubulointerstitial nephropathy caused by unilateral ureteral obstruction.

    Science.gov (United States)

    Kido, Takamasa; Tsunoda, Masashi; Sugaya, Chiemi; Hano, Hiroshi; Yanagisawa, Hiroyuki

    2017-12-01

    The contamination of ground water by fluoride has been reported worldwide. Most fluoride (approximately 70%) is filtered by the kidneys; humans or experimental animals with renal damage therefore may be more affected by fluoride exposure than those with normal kidney function. Tubulointerstitial fibrosis, which involves macrophage-promoted extracellular matrix production and myofibroblast migration, can be induced in rats by unilateral ureteral obstruction (UUO). We examined the effects of fluoride exposure on tubulointerstitial fibrosis in the obstructed kidney of UUO rats. The left ureters of 6-week-old male rats were ligated using silk sutures. Fluoride was then administered for 2 weeks at doses of 0, 75, and 150ppm in the drinking water. Real-time polymerase chain reaction was performed to analyze transforming growth factor beta 1 (TGF-β 1 ) transcription; histological and immunohistochemical staining were used to identify positive areas within the renal cortex and staining-positive cells by image analysis. Significant increases were observed in the obstructed kidneys of UUO rats exposed to 150ppm fluoride (compared to 0ppm) for areas or number of cells that stained with Masson trichrome or with antibodies against collagen type I, alpha-smooth muscle actin (α-SMA, a myofibroblast marker), ED1, ED2, and ED3 (macrophage markers), and TGF-β 1 . Taken together, these observations suggested that fluoride exacerbates tuburointerstitial nephropathy resulting from UUO, and that this effect occurs via activation of the M2 macrophage-TGF-β1-fibroblast/myofibroblast-collagen synthesis pathway. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Evaluation of the fluoride stability of dentifrices sold in Manaus, AM, Brazil Estabilidade do fluoreto de dentifrícios comercializados em Manaus, AM, Brasil

    Directory of Open Access Journals (Sweden)

    Nikeila Chacon de Oliveira Conde

    2003-09-01

    Full Text Available The minimum requirement for the anti-caries effect of a dentifrice is the presence of available and stable fluoride in the formulation. The concentration of available fluoride in the major dentifrices sold in Brazil has been reported, but few data have been published about its stability, which is temperature-dependent. Thus, the aim of this study was to evaluate the concentration and stability of fluoride in dentifrices sold in Manaus, AM, Brazil, which is a typical tropical city. The concentrations of total fluoride, total soluble fluoride, MFP, and of insoluble fluoride of six Brazilian dentifrices and an imported one were analyzed. The analyses were made when the dentifrices were purchased and during a year of storage at room temperature (28.9 ± 1.16°C and under refrigeration (26.3 ± 0.88°C. The analyses were performed using an ion specific electrode Orion 96-09. At the time of purchase, all the dentifrices analyzed showed more than 1,000 ppm (mug F-/g; w/w of soluble fluoride. However, in most of them, this form of fluoride was not shown to be stable. The highest loss of soluble fluoride was found for storage at room temperature, reaching up to 40%. Although all dentifrices comply with the Brazilian guidelines with regard to the concentration of total fluoride (maximum of 0.15%, the instability of soluble fluoride observed in some of them can impair their anti-caries effect and this condition is not contemplated in the Governmental rules.O requisito mínimo para que um dentifrício tenha potencial anticárie é ele ter uma formulação com fluoreto na forma solúvel e estável. A concentração de fluoreto solúvel nos dentifrícios vendidos no Brasil tem sido descrita, mas pouco é conhecido sobre sua estabilidade, a qual é função da temperatura. Assim, o objetivo deste estudo foi avaliar a concentração e estabilidade do fluoreto em dentifrícios vendidos em Manaus, AM, Brasil. As concentrações de fluoreto total, fluoreto sol