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Sample records for hydrogen fluoride samples

  1. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2010 CFR

    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...

  2. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 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...

  3. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 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...

  4. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 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...

  5. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 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...

  6. Vapor-liquid equilibria for the systems difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride

    SciTech Connect

    Kang, Y.W.

    1998-01-01

    Isothermal vapor-liquid equilibria for difluoromethane + hydrogen fluoride, dichlorodifluoromethane + hydrogen fluoride, and chlorine + hydrogen fluoride have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. The binary system difluoromethane + hydrogen fluoride forms a homogeneous liquid phase, and the others form minimum boiling heterogeneous azeotropes at the experimental conditions.

  7. Anhydrous hydrogen fluoride electrolyte battery. [Patent application

    DOEpatents

    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)

  8. Discovery of Interstellar Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Zmuidzinas, Jonas; Schilke, Peter; Phillips, Thomas G.

    1997-01-01

    We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2-1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of approximately 3 x 10(exp -10) relative to H2. If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for approximately 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus, the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously been reached for the case of chlorine in dense interstellar clouds. We also find evidence at a lower level of statistical significance (approximately 5 sigma) for an emission feature at the expected position of the 4(sub 32)-4(sub 23) 121.7219 micron line of water. The emission-line equivalent width of 0.5 nm for the water feature is consistent with the water abundance of 5 x 10(exp -6) relative to H2 that has been inferred previously from observations of the hot core of Sgr B2.

  9. Discovery of Interstellar Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Zmuidzinas, Jonas; Schilke, Peter; Phillips, Thomas G.

    1997-01-01

    We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2-1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of about 3 x 10 (exp -10) relative to H, If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for about 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus, the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously been reached for the case of chlorine in dense interstellar clouds. We also find evidence at a lower level of statistical significance (about 5 sigma) for an emission feature at the expected position of the 4(sub 32)-4(sub 23) 121.7219 micron line of water. The emission-line equivalent width of 0.5 mm for the water feature is consistent with the water abundance of 5 x 10(exp -6) relative to H, that has been inferred previously from observations of the hot core of Sgr B2.

  10. Isothermal vapor-liquid equilibria for the systems 1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodifluoromethane + hydrogen fluoride

    SciTech Connect

    Kang, Y.W.; Lee, Y.Y.

    1997-03-01

    Isothermal vapor-liquid equilibria for the three binary systems (1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodifluoromethane + hydrogen fluoride) have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen fluoride, and the relevant parameters are presented. All of the systems form minimum boiling heterogeneous azeotropes.

  11. Determination of Stability Constants of Hydrogen and Aluminum Fluorides with a Fluoride-Selective Electrode

    SciTech Connect

    Baumann, E.W.

    2003-01-06

    The ability to directly determine free fluoride ion concentration (or mean activity) simplifies gathering and interpretation of experimental data for studies of metal complexes. In this work, the new lanthanum fluoride electrode was used to measure free fluoride ion in an investigation of the hydrogen-fluoride and aluminum-fluoride systems in NH4NO3.

  12. Diffusion of hydrogen fluoride in solid parahydrogen

    NASA Astrophysics Data System (ADS)

    Ooe, Hiroki; Miyamoto, Yuki; Kuma, Susumu; Kawaguchi, Kentarou; Nakajima, Kyo; Nakano, Itsuo; Sasao, Noboru; Tang, Jian; Taniguchi, Takashi; Yoshimura, Motohiko

    2013-06-01

    We studied diffusion of hydrogen fluoride (HF) in solid parahydrogen (pH2) around 4 K. Diffusion rates were determined from time dependence of FT-IR spectra of HF monomers. The absorption of HF monomers shows temporal decay due to dimerization reaction via diffusion. It was found that the rates are affected by the sample temperature, the initial HF concentration, and annealing of samples. The observed non-Arrhenius-type temperature dependence suggests that the diffusion is dominated by a quantum tunneling process, that is, "quantum diffusion." Deceleration of the diffusion in condensed samples and acceleration in annealed samples were also observed. These results can be attributed to the fact that lower periodicity of samples due to impurities or defects suppresses the quantum tunneling. It seems to be difficult to explain the observed dependences by three possible diffusion mechanisms, exchange of chemical bonds, direct cyclic exchange, and exchange with mobile vacancy. Therefore, we propose a hypothetical mechanism by exchange of vacancies originating from quantum effect.

  13. Integral equation study of liquid hydrogen fluoride

    NASA Astrophysics Data System (ADS)

    Martín, C.; Lombardero, M.; Anta, J. A.; Lomba, E.

    2001-01-01

    Liquid hydrogen fluoride is a well-known hydrogen bonded substance, in many aspects related to liquid water, and for which a wide variety of interaction models have recently been proposed. We have studied two of these models by means of a reference hypernetted chain equation in order to assess the ability of this latter approach to describe the properties of this highly associative system. Our calculations, when compared with molecular dynamic results, show that the integral equation reproduces quantitatively both the structure and the thermodynamics of liquid hydrogen fluoride over a wide range of thermodynamic states. However, the integral equation approach is apparently unable to produce estimates for the phase diagram since the low-density (gas phase) side of the binodal curve lies inside the nonsolution region of the equation. This failure can be understood as the result of the inability of standard integral equation theories to account for the behavior of low density strongly associative systems like highly charged electrolytes or, in this case, the gaseous phase of hydrogen fluoride.

  14. Intercomparison of measurements of stratospheric hydrogen fluoride

    NASA Technical Reports Server (NTRS)

    Mankin, William G.; Coffey, M. T.; Chance, K. V.; Traub, W. A.; Carli, B.; Mencaraglia, F.; Piccioli, S.; Farmer, C. B.; Seals, R. K.

    1990-01-01

    Observations of the vertical profile of hydrogen fluoride (HF) vapor in the stratosphere and of the vertical column amounts of HF above certain altitudes were made using a variety of spectroscopic instruments in the 1982 and 1983 Balloon Intercomparison Campaigns. Both emission instruments working in the far-infrared spectral region and absorption instruments using solar occultation in the 2.5-micron region were employed. No systematic differences were seen in results from the two spectral regions. A mean profile from 20 - 45 km is presented, with uncertainties ranging from 20 to 50 percent. Total columns measured from ground and from 12 km are consistent with the profile if the mixing ratio for HF is small in the troposphere and low stratosphere.

  15. Hydrogen fluoride and deuterium fluoride lasers. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Mauk, S. C.

    1980-01-01

    Research cited from the international literature adresses various aspects of hydrogen fluoride and deuterium fluoride lasers. Topics covered include flows, laser outputs, molecular relaxation, molecular rotation, energy conversion efficiency, reaction kinetics, and laser materials. Continous wave and pulsed laser are considered. This updated bibliography contains 283 citations, 53 of which are new additions to the previous edition.

  16. Methods of controlling hydrogen fluoride pressure during chemical fabrication processes

    SciTech Connect

    Solovyov, Vyacheslav; Wiesmann, Harold

    2009-11-24

    The present invention is a method for producing a crystalline end-product. The method comprising exposing a fluoride-containing precursor to a hydrogen fluoride absorber under conditions suitable for the conversion of the precursor into the crystalline end-product.

  17. Sample environment and experimental setup for inelastic x-ray scattering measurements of liquid hydrogen fluoride and (HF){sub x}(H{sub 2}O){sub 1-x} solutions

    SciTech Connect

    Angelini, R.; Giura, P.; Henriquet, C.; Monaco, G.; Verbeni, R.; Ruocco, G.; Sette, F.

    2005-01-01

    In order to study the dynamic structure factor of hydrogen fluoride and its water solutions, we have realized a sample container able to resist these highly reacting hydrogen-bonded liquids and suitable for near-forward x-ray scattering experiments. The design and development of each part of the apparatus together with a discussion on the choice of the materials is reported. Two cells have been built for pure HF and for (HF){sub x}(H{sub 2}O){sub 1-x} solutions based on similar schemes but developed with different materials and some structural variations. Their contribution to the total scattered intensity has been measured. An example of inelastic x-ray scattering spectra at fixed temperature (T=283 K) and momentum transfer (Q=4 nm{sup -1}) is reported as a function of the concentration of hydrogen fluoride [(HF){sub x}(H{sub 2}O){sub 1-x},with x=0,0.2,0.4,0.73,1].

  18. Quantitative infrared analysis of hydrogen fluoride

    SciTech Connect

    Manuta, D.M.

    1997-04-01

    This work was performed at the Portsmouth Gaseous Diffusion Plant where hydrogen fluoride is produced upon the hydrolysis of UF{sub 6}. This poses a problem for in this setting and a method for determining the mole percent concentration was desired. HF has been considered to be a non-ideal gas for many years. D. F. Smith utilized complex equations in his HF studies in the 1950s. We have evaluated HF behavior as a function of pressure from three different perspectives. (1) Absorbance at 3877 cm{sup -1} as a function of pressure for 100% HF. (2) Absorbance at 3877 cm{sup -1} as a function of increasing partial pressure HF. Total pressure = 300 mm HgA maintained with nitrogen. (3) Absorbance at 3877 cm{sup -1} for constant partial pressure HF. Total pressure is increased to greater than 800 mm HgA with nitrogen. These experiments have shown that at partial pressures up to 35mm HgA, HIF follows the ideal gas law. The absorbance at 3877 cm{sup -1} can be quantitatively analyzed via infrared methods.

  19. Hydrogen desorption kinetics for aqueous hydrogen fluoride and remote hydrogen plasma processed silicon (001) surfaces

    SciTech Connect

    King, Sean W. Davis, Robert F.; Carter, Richard J.; Schneider, Thomas P.; Nemanich, Robert J.

    2015-09-15

    The desorption kinetics of molecular hydrogen (H{sub 2}) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H{sub 2} desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH{sub 2/3}), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150 °C), while predominantly monohydride species were observed after higher temperature exposure (450 °C). The ratio of surface versus subsurface H{sub 2} desorption was also found to be dependent on the substrate temperature with 150 °C remote hydrogen plasma exposure generally leading to more H{sub 2} evolved from subsurface states and 450 °C exposure leading to more H{sub 2} desorption from surface SiH{sub x} species. Additional surface desorption states were observed, which were attributed to H{sub 2} desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H{sub 2} desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.

  20. Effects of a documented hydrogen fluoride leak

    SciTech Connect

    Feder, W.A.

    1985-01-01

    At about 6 a.m. on June 19, 1984, 1037 liters of pressurized HF liquid escaped from a storage tank through a 2 mm diameter hole. 48 hours after the leak was discovered and sealed, visible injury to vegetation was observed 2 miles downwind of the source in a tear drop pattern. Injury symptoms ranged from a slight browning of leaves and needles to death of twigs and leaves and needles. Poplar, white pine, spruce, oak, red maple and several herbaceous plant species were injured. Ragweed was not injured but sensitive fern was severely injured. Goldenrod was also injured but recovered within 3 weeks after exposure. White pine trees within 1/4 of a mile from the source were killed. Fluoride analysis of tissues from upwind and downwind trees and herbaceous plants revealed fluoride tissue levels ranging from 5 to 34,000 ppm. Examples of distance/concentration are given. Soils revealed fluoride levels of about 1 ppm at all locations.

  1. Monitoring of fluoride in water samples using a smartphone.

    PubMed

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

    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 0-2mgl(-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. PMID:26874766

  2. Thermodynamic modeling of hydrogen fluoride production relevant to actinide residue treatment

    SciTech Connect

    West, M.H.; Axler, K.M.

    1995-02-01

    This report addresses issues specific to generation of hydrogen fluoride via reaction of calcium fluoride with sulfuric acid. This process has been established on a commercial scale and is under consideration for treatment of calcium fluoride residues from uranium processing. Magnesium fluoride slags are also available as a product of uranium processing. The technique of using sulfuric acid for the production of hydrogen fluoride from magnesium fluoride is also under consideration as a residue processing scheme. In the current study, thermodynamic modeling was used to investigate these chemical processing systems. Results presented herein reveal information relevant to selection of processing temperatures and conditions. Details include predicted effects in system composition based on operating temperatures for both the calcium fluoride and the magnesium fluoride systems.

  3. Atomic layer deposition of magnesium fluoride via bis(ethylcyclopentadienyl)magnesium and anhydrous hydrogen fluoride

    SciTech Connect

    Hennessy, John Jewell, April D.; Greer, Frank; Lee, Michael C.; Nikzad, Shouleh

    2015-01-15

    A new process has been developed to deposit magnesium fluoride (MgF{sub 2}) thin films via atomic layer deposition (ALD) for use as optical coatings in the ultraviolet. MgF{sub 2} was deposited in a showerhead style ALD reactor using bis(ethylcyclopentadienyl)magnesium and anhydrous hydrogen fluoride (HF) as precursors at substrate temperatures from 100 to 250 °C. The use of HF was observed to result in improved morphology and reduced impurity content compared to other reported MgF{sub 2} ALD approaches that use metal fluoride precursors as the fluorine-containing chemistry. Characterization of these films has been performed using spectroscopic ellipsometry, atomic force microscopy, and x-ray photoelectron spectroscopy for material deposited on silicon substrates. Films at all substrate temperatures were transparent at wavelengths down to 190 nm and the low deposition temperature combined with low surface roughness makes these coatings good candidates for a variety of optical applications in the far ultraviolet.

  4. Development and demonstration of a personal monitoring system for exposure to hydrogen fluoride. Final report

    SciTech Connect

    Young, M.S.; Monat, J.P.

    1993-09-01

    A good, functional Hydrogen Fluoride Gasbadge dosimeter has been developed for sampling of airborne HF vapor. The device is small (7.7 cm {times} 5.4 cm {times} 1.9 cm) and can easily and conveniently be worn on one`s lapel. It consists of polyethylene and polypropylene parts and a triethanolamine-impregnated polyproylene collection element. It is completely self contained, requiring no pumps, impingers, or sampling tubes. Subsequent to sampling, the collection element is analyzed quickly and easily with a fluoride selective-ion electrode. Laboratory tests were conducted to determine precision, linearity, interference effects, influences of temperature and humidity, and collection element stability over time. Results of the tests indicate that the Abcor Gasbadge HF dosimeter is an excellent passive HF monitor for work spaces, and that results obtained with it are accurate within {plus_minus}25%. These results have been corroborated in a field study.

  5. Glycine hydrogen fluoride: Remarkable hydrogen bonding in the dimeric glycine glycinium cation

    NASA Astrophysics Data System (ADS)

    Fleck, M.; Ghazaryan, V. V.; Petrosyan, A. M.

    2010-12-01

    Crystals of glycine hydrogen fluoride (Gly·HF) were prepared from an aqueous solution containing stoichiometric quantities of the components. The crystal structure of Gly·HF was determined, IR and Raman spectra were registered and are discussed. Gly·HF crystallizes in the orthorhombic space group Pbca with Z = 32. The most remarkable feature of the structure is the existence of symmetric dimeric glycine-glycinium cations with short hydrogen bonds (O⋯O distance of 2.446 Å), charge-counterbalanced by hydrogen bifluoride (F sbnd H⋯F) - anions - in addition to the expected glycinium cations and fluoride anions. These results were compared with previously published data on crystals grown in the system glycine-HF-H 2O.

  6. First principles Monte Carlo simulations of aggregation in the vapor phase of hydrogen fluoride

    SciTech Connect

    McGrath, Matthew J.; Ghogomu, Julius. N.; Mundy, Christopher J.; Kuo, I-F. Will; Siepmann, J. Ilja

    2010-01-01

    The aggregation of superheated hydrogen fluoride vapor is explored through the use of Monte Carlo simulations employing Kohn-Sham density functional theory with the exchange/correlation functional of Becke-Lee-Yang-Parr to describe the molecular interactions. Simulations were carried out in the canonical ensemble for a system consisting of ten molecules at constant density (2700 Å3/molecule) and at three different temperatures (T = 310, 350, and 390 K). Aggregation-volume-bias and configurational-bias Monte Carlo approaches (along with pre-sampling with an approximate potential) were employed to increase the sampling efficiency of cluster formation and destruction.

  7. Microscopic dynamics and relaxation processes in liquid hydrogen fluoride

    SciTech Connect

    Angelini, R.; Giura, P.; Monaco, G.; Sette, F.; Fioretto, D.; Ruocco, G.

    2004-12-01

    Inelastic x-ray scattering and Brillouin light scattering measurements of the dynamic structure factor of liquid hydrogen fluoride have been performed in the temperature range T=214-283 K. The data, analyzed using a viscoelastic model with a two time-scale memory function, show a positive dispersion of the sound velocity c(Q) between the low frequency value c{sub 0}(Q) and the high frequency value c{sub {infinity}}{sub {alpha}}(Q). This finding confirms the existence of a structural ({alpha}) relaxation directly related to the dynamical organization of the hydrogen bonds network of the system. The activation energy E{sub a} of the process has been extracted by the analysis of the temperature behavior of the relaxation time {tau}{sub {alpha}}(T) that follows an Arrhenius law. The obtained value for E{sub a}, when compared with that observed in another hydrogen bond liquid as water, suggests that the main parameter governing the {alpha}-relaxation process is the number of hydrogen bonds per molecule.

  8. Hydrogen desorption from hydrogen fluoride and remote hydrogen plasma cleaned silicon carbide (0001) surfaces

    SciTech Connect

    King, Sean W. Tanaka, Satoru; Davis, Robert F.; Nemanich, Robert J.

    2015-09-15

    Due to the extreme chemical inertness of silicon carbide (SiC), in-situ thermal desorption is commonly utilized as a means to remove surface contamination prior to initiating critical semiconductor processing steps such as epitaxy, gate dielectric formation, and contact metallization. In-situ thermal desorption and silicon sublimation has also recently become a popular method for epitaxial growth of mono and few layer graphene. Accordingly, numerous thermal desorption experiments of various processed silicon carbide surfaces have been performed, but have ignored the presence of hydrogen, which is ubiquitous throughout semiconductor processing. In this regard, the authors have performed a combined temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) investigation of the desorption of molecular hydrogen (H{sub 2}) and various other oxygen, carbon, and fluorine related species from ex-situ aqueous hydrogen fluoride (HF) and in-situ remote hydrogen plasma cleaned 6H-SiC (0001) surfaces. Using XPS, the authors observed that temperatures on the order of 700–1000 °C are needed to fully desorb C-H, C-O and Si-O species from these surfaces. However, using TPD, the authors observed H{sub 2} desorption at both lower temperatures (200–550 °C) as well as higher temperatures (>700 °C). The low temperature H{sub 2} desorption was deconvoluted into multiple desorption states that, based on similarities to H{sub 2} desorption from Si (111), were attributed to silicon mono, di, and trihydride surface species as well as hydrogen trapped by subsurface defects, steps, or dopants. The higher temperature H{sub 2} desorption was similarly attributed to H{sub 2} evolved from surface O-H groups at ∼750 °C as well as the liberation of H{sub 2} during Si-O desorption at temperatures >800 °C. These results indicate that while ex-situ aqueous HF processed 6H-SiC (0001) surfaces annealed at <700 °C remain terminated by some surface C–O and

  9. Fluoride

    MedlinePlus

    Fluoride is used to prevent tooth decay. It is taken up by teeth and helps to strengthen ... and block the cavity-forming action of bacteria. Fluoride usually is prescribed for children and adults whose ...

  10. Modeling phase equilibria in mixtures containing hydrogen fluoride and halocarbons

    SciTech Connect

    Lencka, M. ); Anderko, A. Polish Academy of Sciences, Warszawa )

    1993-03-01

    Recently, much attention has been focused on the production of environmentally acceptable refrigerants, which not only offer desirable physico-chemical properties, but do not deplete the ozone layer and do not cause the greenhouse effect. The production of such refrigerants involves the separation of multicomponent mixtures containing hydrogen fluoride, hydrogen chloride, and various chlorinated and fluorinated hydrocarbons. Therefore, it is indispensable to know the phase behavior of these mixtures. While the phase behavior of refrigerant mixtures can be adequately modeled in the absence of HF using standard thermodynamic techniques, drastically increases the complexity of the mixture because of its unusually strong association. The association of HF manifests itself in its significantly reduced gas-phase compressibility factor and the strong nonideality of mixtures containing HF and hydrocarbons or halocarbons. In this work, the authors develop an accurate, yet simple, association model for HF and compare it with simulation data. The model is combined with a simple equation of state to yield a closed-form expression that is applicable to both pure fluids and mixtures. In addition to representing the pure-component data for HF, the theory accurately predicts phase equilibria in HF + halocarbon systems.

  11. HYDROGEN FLUORIDE IN HIGH-MASS STAR-FORMING REGIONS

    SciTech Connect

    Emprechtinger, M.; Monje, R. R.; Lis, D. C.; Phillips, T. G.; Van der Tak, F. F. S.; Van der Wiel, M. H. D.; Neufeld, D.; Ceccarelli, C.

    2012-09-10

    Hydrogen fluoride (HF) has been established to be an excellent tracer of molecular hydrogen in diffuse clouds. In denser environments, however, the HF abundance has been shown to be approximately two orders of magnitude lower. We present Herschel/HIFI observations of HF J = 1-0 toward two high-mass star formation sites, NGC 6334 I and AFGL 2591. In NGC 6334 I the HF line is seen in absorption in foreground clouds and the source itself, while in AFGL 2591 HF is partially in emission. We find an HF abundance with respect to H{sub 2} of 1.5 Multiplication-Sign 10{sup -8} in the diffuse foreground clouds, whereas in the denser parts of NGC 6334 I we derive a lower limit on the HF abundance of 5 Multiplication-Sign 10{sup -10}. Lower HF abundances in dense clouds are most likely caused by freezeout of HF molecules onto dust grains in high-density gas. In AFGL 2591, the view of the hot core is obstructed by absorption in the massive outflow, in which HF is also very abundant (3.6 Multiplication-Sign 10{sup -8}) due to the desorption by sputtering. These observations provide further evidence that the chemistry of interstellar fluorine is controlled by freezeout onto gas grains.

  12. Observations of stratospheric hydrogen fluoride by halogen occultation experiment (HALOE)

    NASA Technical Reports Server (NTRS)

    Luo, M.; Cicerone, R. J.; Russel, J. M., III; Huang, T. Y. W.

    1994-01-01

    The Halogen Occultation Experiment (HALOE) Hydrogen Fluoride (HF) channel on the Upper Atmospheric Research Satellite (UARS) is providing the first global measurements of stratospheric HF, the dominant flourine reservoir in the atmosphere. This paper describes the latitudinal and seasonal variations of HALOE-observed HF in terms of vertical profiles, altitude/latitude cross sections, and column abundances. The HF global distribution shows a 'tracerlike' structure and its column amount increases with latitude, in agreement with previous aircraft measurements of the HF column amount. A comparison between the HALOE HF column above 20 km and the ATMOS 1985 measurements is used to estimate the annual rate of increase of stratospheric HF. Exponential rates of 4.9-6.6%/yr and linear growth rates of 6-8.6%/yr in 1985 and 4.3-5.5%/yr in 1992-1993 are found. HALOE HF measurements during the 1993 Antarctic spring are briefly described. This species behaves like a conserved tracer and its distribution shows an area of enhanced mixing ratios correlated with the polar vortex that has a clear latitude boundary. Finally, simulated HF distributions by the National Center for Atmospheric Research (NCAR) two-dimensional model are used to compare with HALOE observations of HF. Reasonable agreements in the global structure and the absolute amount of HF are found. The differences between the model and the observed results indicate the need for improving treatment of atmospheric dynamics and fluorine-related chemical parameters in the model simulations.

  13. Displacement of the proton in hydrogen-bonded complexes of hydrogen fluoride by beryllium and magnesium ions

    SciTech Connect

    McDowell, Sean A. C.

    2009-05-14

    The displacement of the proton by a beryllium ion and by a magnesium ion from hydrogen-bonded complexes of hydrogen fluoride, of varying hydrogen bond strengths, was investigated theoretically using ab initio methods. Stable metal-containing species were obtained from all of the hydrogen-bonded complexes regardless of the strength of the hydrogen bond. It was found that the beryllium ion was energetically very effective in displacing the proton from hydrogen bonds, whereas the magnesium ion was unable to do so. The high stability of the beryllium-containing complexes is mainly due to the strong electrostatic bonding between the beryllium and fluoride atoms. This work supports the recent finding from a multidisciplinary bioinorganic study that beryllium displaces the proton in many strong hydrogen bonds.

  14. Three dimensional simulation of hydrogen chloride and hydrogen fluoride during the Airborne Arctic Stratospheric Expedition

    SciTech Connect

    Kaye, J.A.; Douglass, A.R.; Rood, R.B.; Stolarski, R.S.; Newman, P.A. ); Allen, D.J.; Larson, E.M. ); Coffey, M.T.; Mankin, W.G. ); Toone, G.C. )

    1990-03-01

    Simulations of the evolution of stratospheric distributions of hydrogen chloride (HCl) and hydrogen fluoride (HF) have been carried out for the period of the Airborne Arctic Stratospheric Expedition (AASE) with a three-dimensional chemistry-transport model. Simulations were performed assuming only homogeneous gas phase chemistry for HF and both homogeneous gas phase and heterogeneous chemistry for HCl. Results show heterogeneous loss of HCl is needed to provide agreement with infrared column measurements. Estimates of the impact of heterogeneous loss on the global HCl distribution are obtained from the model. Reductions of HCl due to heterogeneous loss are calculated to be localized to regions of high vorticity, even after more than a month of integration.

  15. Three dimensional simulation of hydrogen chloride and hydrogen fluoride during the Airborne Arctic Stratospheric Expedition

    NASA Technical Reports Server (NTRS)

    Kaye, Jack A.; Rood, Richard B.; Stolarski, Richard S.; Douglass, Anne R.; Newman, Paul A.; Allen, Dale J.; Larson, Edmund M.; Coffey, Michael T.; Mankin, William G.; Toon, Geoffrey C.

    1990-01-01

    Simulations of the evolution of stratospheric distributions of hydrogen chloride (HCl) and hydrogen fluoride (HF) have been carried out for the period of the Airborne Arctic Stratospheric Expedition (AASE) with a three-dimensional chemistry-transport model. Simulations were performed assuming only homogeneous gas phase chemistry for HF and both homogeneous gas phase and heterogeneous chemistry for HCl. Results show heterogeneous loss of HCl is needed to provide agreement with infrared column measurements. Estimates of the impact of heterogeneous loss on the global HCl distribution are obtained from the model. Reductions of HCl due to heterogeneous loss are calculated to be localized to regions of high vorticity, even after more than a month of integration.

  16. Effect of hydrogen fluoride inhalation on lipid metabolism in guinea pigs

    SciTech Connect

    Philibert, C.; Dousset, J.C.; Rioufol, C.; Bourbon, P. )

    1991-01-01

    The action of fluoride in vivo (exposure 96 hrs to 7 mg/m3) on the metabolism of cyclic AMP and relationship between cAMP and lipid metabolism was investigated. The mean values for cAMP, non esterified fatty acids and cholesterol were significantly increased after hydrogen fluoride exposure. cAMP is directly responsible for the increased lipolysis. In animals exposed to HF, theophylline injection causes increases of non esterified fatty acids and not produces modification of cholesterol level.

  17. The Contrasting Character of Early and Late Transition Metal Fluorides as Hydrogen Bond Acceptors.

    PubMed

    Smith, Dan A; Beweries, Torsten; Blasius, Clemens; Jasim, Naseralla; Nazir, Ruqia; Nazir, Sadia; Robertson, Craig C; Whitwood, Adrian C; Hunter, Christopher A; Brammer, Lee; Perutz, Robin N

    2015-09-16

    The association constants and enthalpies for the binding of hydrogen bond donors to group 10 transition metal complexes featuring a single fluoride ligand (trans-[Ni(F)(2-C5NF4)(PR3)2], R = Et 1a, Cy 1b, trans-[Pd(F)(4-C5NF4)(PCy3)2] 2, trans-[Pt(F){2-C5NF2H(CF3)}(PCy3)2] 3 and of group 4 difluorides (Cp2MF2, M = Ti 4a, Zr 5a, Hf 6a; Cp*2MF2, M = Ti 4b, Zr 5b, Hf 6b) are reported. These measurements allow placement of these fluoride ligands on the scales of organic H-bond acceptor strength. The H-bond acceptor capability β (Hunter scale) for the group 10 metal fluorides is far greater (1a 12.1, 1b 9.7, 2 11.6, 3 11.0) than that for group 4 metal fluorides (4a 5.8, 5a 4.7, 6a 4.7, 4b 6.9, 5b 5.6, 6b 5.4), demonstrating that the group 10 fluorides are comparable to the strongest organic H-bond acceptors, such as Me3NO, whereas group 4 fluorides fall in the same range as N-bases aniline through pyridine. Additionally, the measurement of the binding enthalpy of 4-fluorophenol to 1a in carbon tetrachloride (-23.5 ± 0.3 kJ mol(-1)) interlocks our study with Laurence's scale of H-bond basicity of organic molecules. The much greater polarity of group 10 metal fluorides than that of the group 4 metal fluorides is consistent with the importance of pπ-dπ bonding in the latter. The polarity of the group 10 metal fluorides indicates their potential as building blocks for hydrogen-bonded assemblies. The synthesis of trans-[Ni(F){2-C5NF3(NH2)}(PEt3)2], which exhibits an extended chain structure assembled by hydrogen bonds between the amine and metal-fluoride groups, confirms this hypothesis.

  18. Physics and Chemistry of the Hydrogen Fluoride Production Process from Fluorine Containing Waste

    NASA Astrophysics Data System (ADS)

    Dyachenko, A. N.; Kraydenko, R. I.; Lesnikova, M. S.; Malyutin, L. N.; Petlin, I. V.

    2016-06-01

    The impact of the aluminum industry wastes on the environment is established. The resource efficient method of aluminum industry fluorine-containing wastes processing, which includes wastes oxidizing roasting to remove carbon component and the interaction of fluorine- containing particles with sulfuric acid in order to produce hydrogen fluoride, is considered. The economic and environmental effect of the proposed processing method is substantiated.

  19. Hydrogen bonding and catalysis of solvolysis of 4-methoxybenzyl fluoride.

    PubMed

    Toteva, Maria M; Richard, John P

    2002-08-21

    Values of k(o) = 8.0 x 10(-3) s(-1) and k(H) = 2.5 x 10(-2) M(-1) s(-1), respectively, were determined for the spontaneous and the acid-catalyzed cleavage of 4-methoxybenzyl fluoride (1-F) to form the 4-methoxybenzyl carbocation (1+). Values of k(F) = 1.8 x 10(7) M(-1) s(-1) and k(HF) = 7.2 x 10(4) M(-1) s(-1) were determined for addition of F- and HF to 1+ for reaction in the microscopic reverse direction. Evidence is presented that the reversible addition of HF to 1+ to give 1-F + H+ proceeds by a concerted reaction mechanism. The relatively small 250-fold difference between the reactivities of fluoride ion and neutral HF toward 1+ is attributed to the tendency of the strong aqueous solvation of F- to decrease its nucleophilic reactivity and to the advantage for the concerted compared with the usual stepwise pathway for addition of HF. There is no significant stabilization of the transition state for cleavage of 1-F from general acid catalysis by 0.80 M cyanoacetate buffer at pH 1.7. The estimated 3 kcal/mol larger Marcus intrinsic barrier for heterolytic cleavage of 1-F than for cleavage of 1-Cl is attributed to a lag in the development at the transition state of the ca. 30 kcal/mol greater stabilizing solvation of the product ion F- compared with Cl-. The decrease in the electronegativity of X along the series X = F, OH, Cl is accompanied by a ca. 10(10)-fold increase in the carbon basicity compared with the proton basicity of X-.

  20. First principles simulation of a superionic phase of hydrogen fluoride (HF) at high pressures and temperatures

    SciTech Connect

    Goldman, N; Fried, L E

    2006-04-10

    The authors have conducted Ab initio molecular dynamics simulations of hydrogen fluoride (HF) at pressures of 5-66 GPa along the 900 K isotherm. They predict a superionic phase at 33 GPa, where the fluorine atoms are fixed in a bcc lattice while the hydrogen atoms diffuse rapidly with a diffusion constant of between 2 x 10{sup -5} and 5 x 10{sup -5} cm{sup 2}/s. They find that a transformation from asymmetric to symmetric hydrogen bonding occurs in HF at 66 GPa and 900 K. With superionic HF they have discovered a model system where symmetric hydrogen bonding occurs at experimentally achievable conditions. Given previous results on superionic H{sub 2}O[1,2,3] and NH{sub 3}[1], they conclude that high P,T superionic phases of electronegative element hydrides could be common.

  1. [Micro-determination of fluoride in biological samples by pyrohydrolysis and flow-injection analysis using a fluoride ion-selective electrode].

    PubMed

    Itai, K

    1991-02-01

    An apparatus has been developed for the isolation of fluoride in biological samples through pyrohydrolysis. With this apparatus, it is possible to determine both organic and inorganic fluorocompounds with a recovery close to 100% and precision within 5%. The high recovery rate can be expected even for highly heat-resistant compounds such as CaF2, without using WO3 as a catalyst. For determination of the isolated fluoride, a separate apparatus was developed in which flow-injection analysis was used in conjunction with a fluoride ion-selective electrode as a detector. With this apparatus, fluoride in a sample solution with a volume as small as 0.2 ml, and at a concentration as low as 0.5 microgram/l, can be determined within 3 minutes with a precision of several percent. Combined use of the two apparatuses makes it possible to determine fluoride in different biological samples within 10-15 minutes with a precision of several percent, free from external contamination. By selecting suitable conditions for analysis and using a 1 g sample, it is possible to determine fluoride at a concentration as low as 5 ng/g. By employing these apparatuses, the fluoride content in different biological samples has been determine and the effectiveness of their use confirmed. PMID:2051632

  2. Rugged, Portable, Real-Time Optical Gaseous Analyzer for Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey; Gonzales, Paula

    2012-01-01

    Hydrogen fluoride (HF) is a primary evolved combustion product of fluorinated and perfluorinated hydrocarbons. HF is produced during combustion by the presence of impurities and hydrogen- containing polymers including polyimides. This effect is especially dangerous in closed occupied volumes like spacecraft and submarines. In these systems, combinations of perfluorinated hydrocarbons and polyimides are used for insulating wiring. HF is both highly toxic and short-lived in closed environments due to its reactivity. The high reactivity also makes HF sampling problematic. An infrared optical sensor can detect promptly evolving HF with minimal sampling requirements, while providing both high sensitivity and high specificity. A rugged optical path length enhancement architecture enables both high HF sensitivity and rapid environmental sampling with minimal gaseous contact with the low-reactivity sensor surfaces. The inert optical sample cell, combined with infrared semiconductor lasers, is joined with an analog and digital electronic control architecture that allows for ruggedness and compactness. The combination provides both portability and battery operation on a simple camcorder battery for up to eight hours. Optical detection of gaseous HF is confounded by the need for rapid sampling with minimal contact between the sensor and the environmental sample. A sensor is required that must simultaneously provide the required sub-parts-permillion detection limits, but with the high specificity and selectivity expected of optical absorption techniques. It should also be rugged and compact for compatibility with operation onboard spacecraft and submarines. A new optical cell has been developed for which environmental sampling is accomplished by simply traversing the few mm-thick cell walls into an open volume where the measurement is made. A small, low-power fan or vacuum pump may be used to push or pull the gaseous sample into the sample volume for a response time of a few

  3. Quantum monte carlo study of the energetics of small hydrogenated and fluoride lithium clusters.

    PubMed

    Moreira, N L; Brito, B G A; Rabelo, J N Teixeira; Cândido, Ladir

    2016-06-30

    An investigation of the energetics of small lithium clusters doped either with a hydrogen or with a fluorine atom as a function of the number of lithium atoms using fixed-node diffusion quantum Monte Carlo (DMC) simulation is reported. It is found that the binding energy (BE) for the doped clusters increases in absolute values leading to a more stable system than for the pure ones in excellent agreement with available experimental measurements. The BE increases for pure, remains almost constant for hydrogenated, and decreases rapidly toward the bulk lithium for the fluoride as a function of the number of lithium atoms in the clusters. The BE, dissociation energy as well as the second difference in energy display a pronounced odd-even oscillation with the number of lithium atoms. The electron correlation inverts the odd-even oscillation pattern for the doped in comparison with the pure clusters and has an impact of 29%-83% to the BE being higher in the pure cluster followed by the hydrogenated and then by the fluoride. The dissociation energy and the second difference in energy indicate that the doped cluster Li3 H is the most stable whereas among the pure ones the more stable are Li2 , Li4 , and Li6 . The electron correlation energy is crucial for the stabilization of Li3 H. © 2016 Wiley Periodicals, Inc. PMID:26992447

  4. Hydrogen Bond and Ligand Dissociation Dynamics in Fluoride Sensing of Re(I)-Polypyridyl Complex.

    PubMed

    Verma, Sandeep; Aute, Sunil; Das, Amitava; Ghosh, Hirendra N

    2015-11-25

    Hydrogen bonding interaction plays an essential role in the early phases of molecular recognition and colorimetric sensing of various anions in aprotic media. In this work, the host-guest interaction between fac-[Re(CO)3Cl(L)] with L = 4-([2,2'-bipyridin]-4-yl)phenol and fluoride ions is investigated for the hydrogen bond dynamics and the changing local coordination environment. The stoichiometric studies using (1)H NMR and ESI-MS spectroscopies have shown that proton transfer in the H-bonded phenol-fluoride complex activates the dissociation of the CO ligand in the Re(I) center. The phenol-to-phenolate conversion during formation of HF2(-) ion induces nucleophilic lability of the CO ligand which is probed by intraligand charge transfer (ILCT) and ligand-to-metal charge transfer (LMCT) transitions in transient absorption spectroscopy. After photoexcitation, phenol-phenoxide conversion rapidly equilibrates in 280 fs time scale and the ensuing excited state [Re(II)(bpy•(-)-phenolate¯) (CO)3Cl]* undergoes CO dissociation in the ultrafast time scale of ∼3 ps. A concerted mechanism of hydrogen cleavage and coordination change is established in anion sensing studies of the rhenium complex. PMID:26514688

  5. Development of Methods for Sampling and Analysis of Particulate and Gaseous Fluorides from Stationary Sources.

    ERIC Educational Resources Information Center

    Peters, E. T.; And Others

    A study was conducted which has resulted in the development of tentative sampling and analysis of fluorides emitted from various stationary sources. The study was directed toward developing and understanding the kinds of species which are present in each source emission. The report presents the following information: review of the various unit…

  6. HERSCHEL/HIFI OBSERVATIONS OF HYDROGEN FLUORIDE TOWARD SAGITTARIUS B2(M)

    SciTech Connect

    Monje, R. R.; Emprechtinger, M.; Phillips, T. G.; Lis, D. C.; Goldsmith, P. F.; Bergin, E. A.; Bell, T. A.; Neufeld, D. A.; Sonnentrucker, P.

    2011-06-10

    Herschel/HIFI observations have revealed the presence of widespread absorption by hydrogen fluoride (HF) J = 1-0 rotational transition, toward a number of Galactic sources. We present observations of HF J = 1-0 toward the high-mass star-forming region Sagittarius B2(M). The spectrum obtained shows a complex pattern of absorption, with numerous features covering a wide range of local standard of rest velocities (-130 to 100 km {sup -1}). An analysis of this absorption yields HF abundances relative to H{sub 2} of {approx}1.3 x 10{sup -8}, in most velocity intervals. This result is in good agreement with estimates from chemical models, which predict that HF should be the main reservoir of gas-phase fluorine under a wide variety of interstellar conditions. Interestingly, we also find velocity intervals in which the HF spectrum shows strong absorption features that are not present, or are very weak, in spectra of other molecules, such as {sup 13}CO (1-0) and CS (2-1). HF absorption reveals components of diffuse clouds with small extinction that can be studied for the first time. Another interesting observation is that water is significantly more abundant than hydrogen fluoride over a wide range of velocities toward Sagittarius B2(M), in contrast to the remarkably constant H{sub 2}O/HF abundance ratio with average value close to unity measured toward other Galactic sources.

  7. Efficacy of 1% sodium fluoride as a preservative in urine samples containing glucose and Candida albicans.

    PubMed

    Lough, P S; Fehn, R

    1993-03-01

    Whether urine samples used in forensic science DUI testing can be compromised by endogenous ethanol production is a recurrent and yet unresolved issue. This study first assessed unpreserved urine samples that were collected, processed, and analyzed repeatedly over 13 to 41 days using a standard gas chromatographic procedure for ethanol analysis. Despite extensive microbial growth, ethanol was not detected in any test sample. The extent of ethanol production in samples supplemented with glucose, Candida albicans, or both was determined to evaluate the potential for ethanol production in urine samples associated with pathological conditions such as urinary tract yeast infections and diabetes mellitus. Ethanol production under each of the above treatment conditions was assessed in the presence and absence of 1% sodium fluoride as a microbial suppressant. Mean ethanol concentrations were determined for unpreserved samples containing urine only (0.003 +/- 0.005 g%), urine plus yeast (0.006 +/- 0.009 g%) and urine plus glucose (0.067 +/- 0.070 g%). Unpreserved samples supplemented with both yeast and glucose attained mean ethanol concentrations of 0.164 +/- 0.057 g% (P < 0.01). Ethanol could not be detected in any corresponding duplicate samples, which were preserved with 1% sodium fluoride. A lack of ethanol production in any of the unpreserved urine samples indicates that false DUI convictions due to endogenous ethanol production are very unlikely. And while endogenous ethanol production is possible in the presence of both glucose and contaminating C. albicans, 1% sodium fluoride completely eliminated microbial fermentation.

  8. Short-Lived HF Molecules in Superionic Hydrogen Fluoride at Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Tsumuraya, Kazuo; Ohde, Yoshiyuki; Oshimi, Tadaaki

    2015-02-01

    The first principles molecular dynamics study enables us to elucidate the existence of short-lived HF molecules in the superionic hydrogen fluoride at an extreme high pressure and a temperature. Three fourth of the immobile fluorines constructs the molecules with lifetime of 8 fs. The ionized fluorines form weak HF bond with the proton in the nearest HF molecule of which the lifetime is 3 fs. The covalent and the Coulomb bonds between the fluorines and the protons form indirect covalent and indirect Coulomb attractions between the di-interstitial protons on the mid-fluorines. The attractions reduce the Haven's ratio of the protons. The absence of the proton dimers indicates a failure of the caterpillar diffusion model or the Frenkel-Kontorova chain model for the superionic diffusion of the protons. The incompletely ionized cations and anions reduce their Coulomb attractions which induce the sublattice melting of smaller size and smaller mass of the protons than the fluorines. The electronic states of the fluoride are intermediate between the ionic crystals and the covalent bonded molecular crystals. The superionic conductors are classified into three groups: they are molecular type, covalent metalloid type, and metallic type conductors.

  9. Liquid structures of water, methanol, and hydrogen fluoride at ambient conditions from first principles molecular dynamics simulations with a dispersion corrected density functional.

    PubMed

    McGrath, Matthew J; Kuo, I-Feng William; Siepmann, J Ilja

    2011-11-28

    Using first principles molecular dynamics simulations in the isobaric-isothermal ensemble (T = 300 K, p = 1 atm) with the Becke-Lee-Yang-Parr exchange/correlation functional and a dispersion correction due to Grimme, the hydrogen bonding networks of pure liquid water, methanol, and hydrogen fluoride are probed. Although an accurate density is found for water with this level of electronic structure theory, the average liquid densities for both hydrogen fluoride and methanol are overpredicted by 50 and 25%, respectively. The radial distribution functions indicate somewhat overstructured liquid phases for all three compounds. The number of hydrogen bonds per molecule in water is about twice as high as for methanol and hydrogen fluoride, though the ratio of cohesive energy over number of hydrogen bonds is lower for water. An analysis of the hydrogen-bonded aggregates revealed the presence of mostly linear chains in both hydrogen fluoride and methanol, with a few stable rings and chains spanning the simulation box in the case of hydrogen fluoride. Only an extremely small fraction of smaller clusters was found for water, indicating that its hydrogen bond network is significantly more extensive. A special form of water with on average about two hydrogen bonds per molecule yields a hydrogen-bonding environment significantly different from the other two compounds.

  10. A new vapor-liquid equilibrium apparatus for hydrogen fluoride containing systems

    SciTech Connect

    Jongcheon Lee; Hwayong Kim; Jong Sung Lim; Jae-Duck Kim; Youn Yong Lee

    1996-12-31

    A new circulating type apparatus has been constructed to obtain reliable equilibrium PTxy data for hydrogen fluoride (HF) containing system. Equilibrium cell with Pyrex windows protected by Teflon PFA sheets to prevent the corrosion was used. Isothermal vapor-liquid equilibrium data for the 1,1-difluoroethane (HFC-152a) + HF system at 288.23 and 298.35 K were obtained, and compared with PTx measurement results. Experimental data were correlated using Lencka and Anderko equation of state for HF with the Wong-Sandler mixing rule as well as the van der Waals one fluid mixing rule. The Wong-Sandler mixing rule gives better results. 5 refs., 3 figs.

  11. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Not Available

    1989-06-01

    Accidental releases of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in larger scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid ratios of 6/1 to 40/1 and higher. 8 refs., 69 figs., 50 tabs.

  12. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Not Available

    1989-06-01

    Accidental release of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous studies experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in a larger facility. The large scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid ratios of 6/1 to 40/1 and higher.

  13. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Not Available

    1989-06-01

    Accidental release of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in a larger facility. The larger scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid ratios of 6/1 to 40/1 and higher.

  14. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Neff, D.E. . Fluid Mechanics and Wind Engineering Lab.)

    1989-06-01

    Accidental releases of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in a larger facility. The large scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid ratios of 6/1 to 40/1 and higher.

  15. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Not Available

    1989-06-01

    Accidental releases of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in a larger facility. The larger scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid ratios of 6/1 to 40/1 and higher.

  16. Response of anaerobes to methyl fluoride, 2-bromoethanesulfonate and hydrogen during acetate degradation.

    PubMed

    Hao, Liping; Lü, Fan; Li, Lei; Shao, Liming; He, Pinjing

    2013-05-01

    To use the selective inhibition method for quantitative analysis of acetate metabolism in methanogenic systems, the responses of microbial communities and metabolic activities, which were involved in anaerobic degradation of acetate, to the addition of methyl fluoride (CH3F), 2-bromoethanesulfonate (BES) and hydrogen were investigated in a thermophilic batch experiment. Both the methanogenic inhibitors, i.e., CH3F and BES, showed their effectiveness on inhibiting CH4 production, whereas acetate metabolism other than acetoclastic methanogenesis was stimulated by BES, as reflected by the fluctuated acetate concentration. Syntrophic acetate oxidation was thermodynamically blocked by hydrogen (H2), while H2-utilizing reactions as hydrogenotrophic methanogenesis and homoacetogenesis were correspondingly promoted. Results of PCR-DGGE fingerprinting showed that, CH3F did not influence the microbial populations significantly. However, the BES and hydrogen notably altered the bacterial community structures and increased the diversity. BES gradually changed the methanogenic community structure by affecting the existence of different populations to different levels, whilst H2 greatly changed the abundance of different methanogenic populations, and induced growth of new species.

  17. DISCOVERY OF HYDROGEN FLUORIDE IN THE CLOVERLEAF QUASAR AT z = 2.56

    SciTech Connect

    Monje, R. R.; Phillips, T. G.; Lis, D. C.; Emprechtinger, M.; Peng, R.; Neufeld, D. A.

    2011-12-15

    We report the first detection of hydrogen fluoride (HF) toward a high-redshift quasar. Using the Caltech Submillimeter Observatory, we detect the HF J = 1-0 transition in absorption toward the Cloverleaf, a broad absorption line quasi-stellar object at z = 2.56. The detection is statistically significant at the {approx}6{sigma} level. We estimate a lower limit of 4 Multiplication-Sign 10{sup 14} cm{sup -2} for the HF column density and using a previous estimate of the hydrogen column density, we obtain a lower limit of 1.7 Multiplication-Sign 10{sup -9} for the HF abundance. This value suggests that, assuming a Galactic N(HF)/N{sub H} ratio, HF accounts for at least {approx}10% of the fluorine in the gas phase along the line of sight to the Cloverleaf quasar. This observation corroborates the prediction that HF should be a good probe of the molecular gas at high redshift. Measurements of the HF abundance as a function of redshift are urgently needed to better constrain the fluorine nucleosynthesis mechanism(s).

  18. Sampling Stoichiometry: The Decomposition of Hydrogen Peroxide.

    ERIC Educational Resources Information Center

    Clift, Philip A.

    1992-01-01

    Describes a demonstration of the decomposition of hydrogen peroxide to provide an interesting, quantitative illustration of the stoichiometric relationship between the decomposition of hydrogen peroxide and the formation of oxygen gas. This 10-minute demonstration uses ordinary hydrogen peroxide and yeast that can be purchased in a supermarket.…

  19. Infrared overtone spectroscopy of hydrogen fluoride van der Waals complexes at upsilon (HF) = 3

    NASA Astrophysics Data System (ADS)

    Tsang, Susy Ngan Ping

    1998-11-01

    The dependence of weak intermolecular forces on valence bond excitations is investigated by the spectroscopy and vibrational predissociation dynamics of four hydrogen fluoride van der Waals complexes, N2HF, (HF)2, Ar2HF and Ar3HF, at the second overtone vibrational excitation of the hydrogen bonded HF intramolecular stretch, v HF=3. The formation and detection of these weakly bound complexes are achieved by the unique combination of slit supersonic jet expansion and intracavity Ti:sapphire laser-induced fluorescence. For the four complexes studied, an increase in the red- shift as a function of v HF was observed in the hydrogen bonded HF valence stretch as a result of the strengthening of the hydrogen bond. In addition, changes in the anisotropies of the intermolecular potentials of these weakly bound systems are in accord with those observed in the prototypical studies of ArHF at v HF=3 in this laboratory. However, the van der Waals soft modes have only been completely characterized for N2HF at v HF=3. Moreover, the frequencies of these intermolecular modes were experimentally determined for the first time in the N2HF complex. Of major interest in the N2HF studies is the intermolecular state dependence of the vibrational predissociation in this complex at v HF=3. Intermolecular state dependent vibrational predissociation dynamics is also observed in the (HF)2 studies. In order to further understand the complex internal dynamics in N2HF, ab initio calculations for a highly accurate four-dimensional potential energy surface using the symmetry adapted perturbation theory (SAPT) method were performed at v HF=0 and at v HF=3. A preliminary analysis of the ab initio data for both vibrational states and bound state calculations for the ground state potential energy surface are presented. The work on the Ar2HF and Ar3HF clusters tests the accuracy of pairwise additive intermolecular potentials for these two systems at v HF=3. In particular, the data obtained on these

  20. Assessment of hydrogen fluoride damage to vegetation using optical remote sensing data

    NASA Astrophysics Data System (ADS)

    Hyun, C. U.; Lee, J. S.; Lee, I.

    2013-10-01

    This research assesses damage to vegetation from accidental gaseous hydrogen fluoride leakage, through the analysis of spectral features of the damaged plants using digital aerial photographs and airborne hyperspectral imagery. The hyperspectral imagery was obtained 21 days after the leakage within visible and near-infrared wavelength range using CASI-1500 imager, and two aerial photographs composed of blue, green, red and near-infrared bands were also obtained in 2 October 2011 and 15 November 2012, respectively. The injuries on leaves and the outline of the leakage affected area were assessed by investigating vegetation index images calculated from the hyperspectral imagery and the aerial photograph obtained in 15 November 2012, with comparison to the index image calculated from the aerial photograph obtained in 12 October 2011. The affected areas were mainly distributed in the east of the leakage point, and this reflects predominant wind directions toward east during the leakage and within 24 hours after the leakage. In addition, the detailed changes in spectral reflectance curves of damaged vegetation were also investigated using the hyperspectral imagery. Paddy field and forest land were identified by cadastral map, and the reference areas for the comparison of the reflectance curve change were designated to each land cover type, by considering the most and least affected areas from the vegetation indices comparison results.

  1. Hydrogen fluoride toward luminous nearby galaxies: NGC 253 and NGC 4945

    SciTech Connect

    Monje, R. R.; Lis, D. C.; Phillips, T. G.; Lord, S.; Falgarone, E.; Güsten, R.

    2014-04-10

    We present the detection of hydrogen fluoride (HF) in two luminous nearby galaxies, NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H{sub 2}){sub out} ∼ 1 × 10{sup 7} M {sub ☉} and an outflow rate as large as M-dot ∼6.4 M {sub ☉} yr{sup –1}. In the case of NGC 4945, the axisymmetric velocity components in the HF line profile are compatible with the interpretation of a fast-rotating nuclear ring surrounding the nucleus and the presence of inflowing gas. The gas falls into the nucleus with an inflow rate of ≤1.2 M {sub ☉} yr{sup –1}, inside an inner radius of ≤200 pc. The gas accretion rate to the central active galactic nucleus is much smaller, suggesting that the inflow may be triggering a nuclear starburst. From these results, the HF J = 1-0 line is seen to provide an important probe of the kinematics of absorbing material along the sight-line to nearby galaxies with bright dust continuum and a promising new tracer of molecular gas in high-redshift galaxies.

  2. Quantum mechanical force field for hydrogen fluoride with explicit electronic polarization

    SciTech Connect

    Mazack, Michael J. M.; Gao, Jiali

    2014-05-28

    The explicit polarization (X-Pol) theory is a fragment-based quantum chemical method that explicitly models the internal electronic polarization and intermolecular interactions of a chemical system. X-Pol theory provides a framework to construct a quantum mechanical force field, which we have extended to liquid hydrogen fluoride (HF) in this work. The parameterization, called XPHF, is built upon the same formalism introduced for the XP3P model of liquid water, which is based on the polarized molecular orbital (PMO) semiempirical quantum chemistry method and the dipole-preserving polarization consistent point charge model. We introduce a fluorine parameter set for PMO, and find good agreement for various gas-phase results of small HF clusters compared to experiments and ab initio calculations at the M06-2X/MG3S level of theory. In addition, the XPHF model shows reasonable agreement with experiments for a variety of structural and thermodynamic properties in the liquid state, including radial distribution functions, interaction energies, diffusion coefficients, and densities at various state points.

  3. Estimation of potential health effects from acute exposure to hydrogen fluoride using a "benchmark dose" approach.

    PubMed

    Alexeeff, G V; Lewis, D C; Ragle, N L

    1993-02-01

    Communities across the United States are examining the manufacture, use, transport, and storage of hydrogen fluoride (HF) near residential areas as a consequence of a major release of HF in Texas in 1987. Reference exposure levels for routine and accidental HF emissions are calculated using existing animal and human data. The approach employs a log-probit extrapolation of concentration-response data to the 95% lower confidence limit on the toxic concentration producing a "benchmark dose" of 1% response (TC01), called a practical threshold. Species-specific and chemical-specific adjustment factors are applied to develop exposure levels applicable to the general public. Using this method, the 1-hr reference exposure level to protect the public against any irritation from a routine emission (REL-1) is 0.7 ppm and the level to protect against severe irritation from a once-in-a-lifetime (REL-2) release is 2 ppm. This approach is compared to a modified "uncertainty factor" approach. PMID:8451461

  4. Quantum mechanical force field for hydrogen fluoride with explicit electronic polarization.

    PubMed

    Mazack, Michael J M; Gao, Jiali

    2014-05-28

    The explicit polarization (X-Pol) theory is a fragment-based quantum chemical method that explicitly models the internal electronic polarization and intermolecular interactions of a chemical system. X-Pol theory provides a framework to construct a quantum mechanical force field, which we have extended to liquid hydrogen fluoride (HF) in this work. The parameterization, called XPHF, is built upon the same formalism introduced for the XP3P model of liquid water, which is based on the polarized molecular orbital (PMO) semiempirical quantum chemistry method and the dipole-preserving polarization consistent point charge model. We introduce a fluorine parameter set for PMO, and find good agreement for various gas-phase results of small HF clusters compared to experiments and ab initio calculations at the M06-2X/MG3S level of theory. In addition, the XPHF model shows reasonable agreement with experiments for a variety of structural and thermodynamic properties in the liquid state, including radial distribution functions, interaction energies, diffusion coefficients, and densities at various state points.

  5. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Holve, D.J.; Harvill, T.L. )

    1989-06-01

    Accidental release of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in a larger facility. The larger scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid rates of 6/1 to 40/1 and higher. 8 refs., 69 figs., 50 tabs.

  6. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride

    SciTech Connect

    Schatz, K.W. ); Koopman, R.P. )

    1989-07-01

    Accidental releases of pressurized, superheated hydrogen fluoride (HF) can result in initially dense clouds which will typically contain a mixture of HF vapor, aerosol, and droplets. Previous experiments were performed by Amoco Oil Company and Lawrence Livermore National Laboratories (the Goldfish series in 1986) to study atmospheric dispersion of these HF clouds. The present study examines the effect of water application on the mitigation of these clouds. To assess the effectiveness of water application (via either sprays or monitor) in mitigating HF clouds two series of tests were conducted in separate flow chambers. Bench scale experiments identified key variables for testing in a larger facility. The larger scale field tests demonstrated that HF releases can be mitigated with water. The impact of numerous design variables on mitigation effectiveness has also been quantified. HF removal efficiencies of 25 to 90+% have been demonstrated at water to HF liquid ratios of 6/1 to 40/1 and higher. 6 refs., 22 figs., 2 tabs.

  7. Hydrogen Fluoride toward Luminous Nearby Galaxies: NGC 253 and NGC 4945

    NASA Astrophysics Data System (ADS)

    Monje, R. R.; Lord, S.; Falgarone, E.; Lis, D. C.; Neufeld, D. A.; Phillips, T. G.; Güsten, R.

    2014-04-01

    We present the detection of hydrogen fluoride (HF) in two luminous nearby galaxies, NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H2)out ~ 1 × 107 M ⊙ and an outflow rate as large as dot M ~6.4 M ⊙ yr-1. In the case of NGC 4945, the axisymmetric velocity components in the HF line profile are compatible with the interpretation of a fast-rotating nuclear ring surrounding the nucleus and the presence of inflowing gas. The gas falls into the nucleus with an inflow rate of <=1.2 M ⊙ yr-1, inside an inner radius of <=200 pc. The gas accretion rate to the central active galactic nucleus is much smaller, suggesting that the inflow may be triggering a nuclear starburst. From these results, the HF J = 1-0 line is seen to provide an important probe of the kinematics of absorbing material along the sight-line to nearby galaxies with bright dust continuum and a promising new tracer of molecular gas in high-redshift galaxies.

  8. Liquid-liquid equilibria for hydrogen fluoride + 1,1-dichloro-1-fluoroethane + 1-chloro-1,1-difluoroethane at {minus}20 and 20 C

    SciTech Connect

    Kang, Y.W.; Lee, Y.Y.

    1995-03-01

    1,1-Dichloro-1-fluoroethane is presently under consideration as a replacement for trichlorofluoromethane, which is widely used as a foam blowing agent. 1-Chloro-1,1-difluoroethane is the major raw material for the production of poly(vinylidene fluoride). These two materials are normally manufactured by the fluorination of 1,1,1-trichloroethane or vinylidene chloride with hydrogen fluoride. A phase separator is normally used to retrieve hydrogen fluoride from the product stream. To design the phase separator, liquid-liquid equilibrium data are required. Liquid-liquid equilibria for the ternary system (hydrogen fluoride + 1,1-dichloro-1-fluoroethane + 1-chloro-1,1-difluoroethane) have been measured at {minus}20 and 20 C. The results are correlated with the NRTL model, and the relevant parameters are presented.

  9. Fluoride sample matrices and reaction cells — new capabilities for isotope measurements in accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kieser, W. E.; Zhao, X.-L.; Eliades, J.; Litherland, A. E.

    2012-04-01

    Two new techniques, which extend the range of elements that can be analyzed by Accelerator Mass Spectrometry (AMS), and which increase its isobar selection capabilities, have been recently introduced. The first consists of embedding the sample material in a fluoride matrix (e.g. PbF2), which facilitates the production, in the ion source, of fluoride molecular anions that include the isotope of interest. In addition to forming anions with large electron binding energies and thereby increasing the range of analysable elements, in many cases by selection of a molecular form with a particular number of fluorine atoms, some isobar discrimination can be obtained. The second technique, for the significant reduction of atomic isobar interferences, is used following mass selection of the rare isotope. It consists of the deceleration, cooling and reaction of the rare mass beam with a gas, selected so that unwanted isobars are greatly attenuated in comparison with the isotope of interest. Proof of principle measurements for the analysis of 36C1 and 41Ca have provided encouraging results and work is proceeding on the integration of these techniques in a new AMS system planned for installation in late 2012 at the University of Ottawa.

  10. Herschel Legacy Survey of Hydrogen Fluoride and Water Towards Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Rodriguez Monje, Raquel

    Hydride molecules, molecules containing just one heavy element atom with one or more hydrogen atoms, play an importance role in interstellar chemistry, as they are often stable end points of chemical reactions, or represent important intermediate stages of the reaction chains theorized to form gas phase molecules. This makes hydride molecules a sensitive test of these chemical models, as well as potential tracers of molecular hydrogen. Due to the low moment of inertia, hydrides have their fundamental rotational transitions in the submillimeter band, blocked by the Earth's atmosphere and in most cases, only accessible with the past NASA mission, Herschel Space Observatory. Two of the key results from Herschel observations are: the first detection of the fundamental J = 1 - 0 rotational transition of hydrogen fluoride (HF) at 1.232 THz (243 μm) and the discovery of HF's ubiquitous nature in the Milky Way. HF has not only been observed toward almost every bright continuum source in the Galactic plane, but also in some nearby ultra luminous galaxies, establishing its importance outside the Milky Way as well. Despite fluorine's (F) relative low abundance in the interstellar medium (ISM) (about four times lower than carbon), F plays an important role in the interstellar chemistry due to the unique thermochemistry of the reaction between F and molecular hydrogen (H2). F is the only atom that reacts exothermically with H2, to form the compound HF. Once formed, HF becomes the main reservoir of fluorine in the ISM, with a strong bond only destroyed by reactions with low abundance ions H3+, C+ and He+, or photodissociation. This unusual stability allows the build up of large amounts of HF in the ISM, which has now been confirmed by Herschel. Chemical model predicted that the ground state rotational transition line of HF J = 1 - 0 would yield an extremely sensitive probe of the diffuse molecular gas along the line-of-sight to background far-infrared continuum sources and a

  11. Hydrogen sulfide production from subgingival plaque samples.

    PubMed

    Basic, A; Dahlén, G

    2015-10-01

    Periodontitis is a polymicrobial anaerobe infection. Little is known about the dysbiotic microbiota and the role of bacterial metabolites in the disease process. It is suggested that the production of certain waste products in the proteolytic metabolism may work as markers for disease severity. Hydrogen sulfide (H2S) is a gas produced by degradation of proteins in the subgingival pocket. It is highly toxic and believed to have pro-inflammatory properties. We aimed to study H2S production from subgingival plaque samples in relation to disease severity in subjects with natural development of the disease, using a colorimetric method based on bismuth precipitation. In remote areas of northern Thailand, adults with poor oral hygiene habits and a natural development of periodontal disease were examined for their oral health status. H2S production was measured with the bismuth method and subgingival plaque samples were analyzed for the presence of 20 bacterial species with the checkerboard DNA-DNA hybridization technique. In total, 43 subjects were examined (age 40-60 years, mean PI 95 ± 6.6%). Fifty-six percent had moderate periodontal breakdown (CAL > 3 < 7 mm) and 35% had severe periodontal breakdown (CAL > 7 mm) on at least one site. Parvimonas micra, Filifactor alocis, Porphyromonas endodontalis and Fusobacterium nucleatum were frequently detected. H2S production could not be correlated to periodontal disease severity (PPD or CAL at sampled sites) or to a specific bacterial composition. Site 21 had statistically lower production of H2S (p = 0.02) compared to 16 and 46. Betel nut chewers had statistically significant lower H2S production (p = 0.01) than non-chewers. Rapid detection and estimation of subgingival H2S production capacity was easily and reliably tested by the colorimetric bismuth sulfide precipitation method. H2S may be a valuable clinical marker for degradation of proteins in the subgingival pocket. PMID:25280920

  12. Isothermal compressibility maxima of hydrogen fluoride in the supercritical and superheated vapor regions.

    PubMed

    Baburao, Barath; Visco, Donald P

    2006-12-28

    The highly nonideal behavior of hydrogen fluoride (HF) vapor has been considered to be the origin of its numerous vapor phase anomalies. In this work, we report one such potential vapor phase anomaly for HF. For a nonassociating substance like propane, the response functions go through a maximum only once in the supercritical region. However, for HF, when an association model is used to predict the isothermal compressibility (KT), it exhibits a maximum in the supercritical region more than once, and this peak extends well in to the superheated vapor region upon decompression. This theoretical prediction is also supported by two other models recently developed for HF. Note that experimental values of KT for HF have not been reported in the literature so far. Preliminary investigations on this KT maximum for HF have suggested no reentrant spinodal, singularity-free scenario, or any additional first-order phase transition, unlike water, and, also, no lambda (or higher-order phase) transitions, unlike liquid helium. However, this KT peak is similar to the experimentally supported heat capacity (CP) peak of HF which extends into the supercritical and superheated vapor regions. Similar to the CP peak, which is understood based on vapor-phase clustering in HF, we relate KT to the derivatives of enthalpy and entropy of the system. Also, we analyze some of the P-v-T experimental data that are available to provide an overview of the KT behavior in the region of interest, and compare them with the model results. Finally, to explore the effect of including a distribution pattern for the oligomers, we report the results on a model that only includes association. Using this approach, we report KT results with and without a Poisson-type oligomer distribution and show that the KT appears once this distribution scheme is specified. PMID:17181277

  13. Ab Initio Calculations of Anharmonic Vibrational Spectroscopy for Hydrogen Fluoride (HF)n (n=3,4) and Mixed Hydrogen Fluoride/Water (HF)n(H20)n (n=1,2,4) Clusters

    NASA Technical Reports Server (NTRS)

    Chaban, Galina M.; Gerber, R. Benny; Kwak, Dochan (Technical Monitor)

    2001-01-01

    Anharmonic vibrational frequencies and intensities are computed for hydrogen fluoride clusters (HF)n with n=3,4 and mixed clusters of hydrogen fluoride with water (HF)n(H2O)n where n=1,2. For the (HF)4(H2O)4 complex, the vibrational spectra are calculated at the harmonic level, and anharmonic effects are estimated. Potential energy surfaces for these systems are obtained at the MP2/TZP level of electronic structure theory. Vibrational states are calculated from the potential surface points using the correlation-corrected vibrational self-consistent field (CC-VSCF) method. The method accounts for the anharmonicities and couplings between all vibrational modes and provides fairly accurate anharmonic vibrational spectra that can be directly compared with experimental results without a need for empirical scaling. For (HF)n, good agreement is found with experimental data. This agreement shows that the MP2 potential surfaces for these systems are reasonably reliable. The accuracy is best for the stiff intramolecular modes, which indicates the validity of MP2 in describing coupling between intramolecular and intermolecular degrees of freedom. For (HF)n(H2O)n experimental results are unavailable. The computed intramolecular frequencies show a strong dependence on cluster size. Intensity features are predicted for future experiments.

  14. Ab initio calculations of anharmonic vibrational spectroscopy for hydrogen fluoride (HF)n (n = 3, 4) and mixed hydrogen fluoride/water (HF)n(H2O)n (n = 1, 2, 4) clusters

    NASA Technical Reports Server (NTRS)

    Chaban, Galina M.; Gerber, R. Benny

    2002-01-01

    Anharmonic vibrational frequencies and intensities are computed for hydrogen fluoride clusters (HF)n, with n = 3, 4 and mixed clusters of hydrogen fluoride with water (HF)n(H2O)n where n = 1, 2. For the (HF)4(H2O)4 complex, the vibrational spectra are calculated at the harmonic level, and anharmonic effects are estimated. Potential energy surfaces for these systems are obtained at the MP2/TZP level of electronic structure theory. Vibrational states are calculated from the potential surface points using the correlation-corrected vibrational self-consistent field method. The method accounts for the anharmonicities and couplings between all vibrational modes and provides fairly accurate anharmonic vibrational spectra that can be directly compared with experimental results without a need for empirical scaling. For (HF)n, good agreement is found with experimental data. This agreement shows that the Moller-Plesset (MP2) potential surfaces for these systems are reasonably reliable. The accuracy is best for the stiff intramolecular modes, which indicates the validity of MP2 in describing coupling between intramolecular and intermolecular degrees of freedom. For (HF)n(H2O)n experimental results are unavailable. The computed intramolecular frequencies show a strong dependence on cluster size. Intensity features are predicted for future experiments.

  15. Satellite observations of stratospheric hydrogen fluoride and comparisons with SLIMCAT calculations

    NASA Astrophysics Data System (ADS)

    Harrison, Jeremy J.; Chipperfield, Martyn P.; Boone, Christopher D.; Dhomse, Sandip S.; Bernath, Peter F.; Froidevaux, Lucien; Anderson, John; Russell, James, III

    2016-08-01

    The vast majority of emissions of fluorine-containing molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Many of these fluorine-containing species deplete stratospheric ozone and are regulated by the Montreal Protocol. Once in the atmosphere they slowly degrade, ultimately leading to the formation of hydrogen fluoride (HF), the dominant reservoir of stratospheric fluorine due to its extreme stability. Monitoring the growth of stratospheric HF is therefore an important marker for the success of the Montreal Protocol. We report the comparison of global distributions and trends of HF measured in the Earth's atmosphere by the satellite remote-sensing instruments ACE-FTS (Atmospheric Chemistry Experiment Fourier transform spectrometer), which has been recording atmospheric spectra since 2004, and HALOE (HALogen Occultation Experiment), which recorded atmospheric spectra between 1991 and 2005, with the output of SLIMCAT, a state-of-the-art three-dimensional chemical transport model. In general the agreement between observation and model is good, although the ACE-FTS measurements are biased high by ˜ 10 % relative to HALOE. The observed global HF trends reveal a substantial slowing down in the rate of increase of HF since the 1990s: 4.97 ± 0.12 % year-1 (1991-1997; HALOE), 1.12 ± 0.08 % year-1 (1998-2005; HALOE), and 0.52 ± 0.03 % year-1 (2004-2012; ACE-FTS). In comparison, SLIMCAT calculates trends of 4.01, 1.10, and 0.48 % year-1, respectively, for the same periods; the agreement is very good for all but the earlier of the two HALOE periods. Furthermore, the observations reveal variations in the HF trends with latitude and altitude; for example, between 2004 and 2012 HF actually decreased in the Southern Hemisphere below ˜ 35 km. An additional SLIMCAT simulation with repeating meteorology for the year 2000 produces much cleaner trends in HF with minimal variations with latitude

  16. Prevalence of certain inorganic constituents in groundwater samples of Erode district, Tamilnadu, India, with special emphasis on fluoride, fluorosis and its remedial measures.

    PubMed

    Karthikeyan, K; Nanthakumar, K; Velmurugan, P; Tamilarasi, S; Lakshmanaperumalsamy, P

    2010-01-01

    A total of 60 drinking water samples collected from Erode district, Tamilnadu, India were analysed for fluoride contamination, besides water quality parameters such as pH, electrical conductivity, total dissolved solids, total alkalinity, total hardness, fluoride, bicarbonates, calcium, magnesium, nitrate, sulphate, phosphate, sodium and potassium. The results obtained were found to exceed the permissible limits. The concentration of fluoride in the water samples ranged between 0.5 and 8.2 mg/l and revealed that 80% of the water samples contain fluoride above the maximum permissible limit. Similarly, the concentrations of nitrate, hardness, calcium and magnesium in some samples were also more than the permissible level. Pearson's correlation coefficient among the parameters showed a positive correlation of fluoride with total hardness and calcium. It is inferred from the study that these water sources can be used for potable purpose only after prior treatment.

  17. Does fluoride disrupt hydrogen bond network in cationic lipid bilayer? Time-dependent fluorescence shift of Laurdan and molecular dynamics simulations.

    PubMed

    Pokorna, Sarka; Jurkiewicz, Piotr; Vazdar, Mario; Cwiklik, Lukasz; Jungwirth, Pavel; Hof, Martin

    2014-12-14

    Time-dependent fluorescence shift (TDFS) of Laurdan embedded in phospholipid bilayers reports on hydration and mobility of the phospholipid acylgroups. Exchange of H2O with D2O prolongs the lifetime of lipid-water and lipid-water-lipid interactions, which is reflected in a significantly slower TDFS kinetics. Combining TDFS measurements in H2O and D2O hydrated bilayers with atomistic molecular dynamics (MD) simulations provides a unique tool for characterization of the hydrogen bonding at the acylgroup level of lipid bilayers. In this work, we use this approach to study the influence of fluoride anions on the properties of cationic bilayers composed of trimethylammonium-propane (DOTAP). The results obtained for DOTAP are confronted with those for neutral phosphatidylcholine (DOPC) bilayers. Both in DOTAP and DOPC H2O/D2O exchange prolongs hydrogen-bonding lifetime and does not disturb bilayer structure. These results are confirmed by MD simulations. TDFS experiments show, however, that for DOTAP this effect is cancelled in the presence of fluoride ions. We interpret these results as evidence that strongly hydrated fluoride is able to steal water molecules that bridge lipid carbonyls. Consequently, when attracted to DOTAP bilayer, fluoride disrupts the local hydrogen-bonding network, and the differences in TDFS kinetics between H2O and D2O hydrated bilayers are no longer observed. A distinct behavior of fluoride is also evidenced by MD simulations, which show different lipid-ion binding for Cl(-) and F(-).

  18. Sensitive determination of fluoride in biological samples by gas chromatography-mass spectrometry after derivatization with 2-(bromomethyl)naphthalene.

    PubMed

    Kwon, Sun-Myung; Shin, Ho-Sang

    2014-12-10

    A gas chromatography-mass spectrometric method was developed in this study in order to determine fluoride in plasma and urine after derivatization with 2-(bromomethyl)naphthalene. 2-Fluoronaphthalene was chosen as the internal standard. The derivatization of fluoride was performed in the biological sample and the best reaction conditions (10.0 mg mL(-1) of 2-(bromomethyl)naphthalene, 1.0 mg mL(-1) of 15-crown-5-ether as a phase transfer catalyst, pH of 7.0, reaction temperature of 70°C, and heating time of 70 min) were established. The organic derivative was extracted with dichloromethane and then measured by a gas chromatography-mass spectrometry. Under the established condition, the detection limits were 11 μg L(-1) and 7 μg L(-1) by using 0.2 mL of plasma or urine, respectively. The accuracy was in a range of 100.8-107.6%, and the precision of the assay was less than 4.3% in plasma or urine. Fluoride was detected in a concentration range of 0.12-0.53 mg L(-1) in six urine samples after intake of natural mineral water containing 0.7 mg L(-1) of fluoride.

  19. Rotationally resolved spectroscopy of a librational fundamental band of hydrogen fluoride tetramer

    NASA Astrophysics Data System (ADS)

    Blake, Thomas A.; Sharpe, Steven W.; Xantheas, Sotiris S.

    2000-07-01

    The rotationally resolved spectrum of a fundamental band of hydrogen fluoride tetramer has been recorded using a pulsed slit-jet, diode laser spectrometer. The band has a parallel rotational structure and is assigned as the H-F out-of-plane libration fundamental with Au symmetry. Ninety-five ground state combination differences were fit to a symmetric top Hamiltonian to give the following ground state rotational constants: B″=0.132 081(7) cm-1, DJ″=7.1(7)×10-7 cm-1, DJK″=-9(2)×10-7 cm-1, HJJJ″=6(2)×10-10 cm-1, HJJK″=9(7)×10-10 cm-1, HJKK″=-1.3(8)×10-10 cm-1. A total of 190 transitions were fit to determine the upper state spectroscopic constants: v4=714.7849(1) cm-1, B'=0.129 634(5) cm-1, Δ(C-B)=0.001 344 cm-1, DJ'=6.4(5)×10-7 cm-1, DJK'=-4.5(6)×10-7 cm-1, ΔDK=2.92(8)×10-6 cm-1, HJJJ'=3(1)×10-10 cm-1, HJKK'=-1.55(6)×10-8 cm-1; ΔHKKK=-4.65(6)×10-8 cm-1. Furthermore, a perpendicular band centered at 752.7 cm-1 was observed. The band has a rotational line spacing that gives an approximate B″ value of 0.132 cm-1; it has been assigned as the Eu symmetry, H-F in-plane libration fundamental of the HF tetramer. Finally, a parallel band was observed at 741.0 cm-1 with B″=0.076 cm-1 and has been assigned as the A″ symmetry, H-F out-of-plane libration fundamental of the HF pentamer. Structural parameters and harmonic vibrational frequencies are estimated from first-principles, correlated MP2 and CCSD(T) calculations. These are the largest calculations performed to date for this system with respect to both orbital basis set and level of electron correlation. The CCSD(T) harmonic frequencies are, in particular, the first reported for the tetramer at this level of theory. Based on our results, we suggest "best estimates" of RFF=2.51 Å, rHF=0.947 Å, and θHFF=9.7° for the structural parameters and a range for De of 27.4 to 28.1 kcal/mol (D0=19.7 to 20.4 kcal/mol) for the parameters and for the energy of the tetramer dissociating into four

  20. Rotationally resolved spectroscopy of a librational fundamental band of hydrogen fluoride tetramer

    SciTech Connect

    Blake, Thomas A.; Sharpe, Steven W.; Xantheas, Sotiris S.

    2000-07-08

    The rotationally resolved spectrum of a fundamental band of hydrogen fluoride tetramer has been recorded using a pulsed slit-jet, diode laser spectrometer. The band has a parallel rotational structure and is assigned as the H-F out-of-plane libration fundamental with A{sub u} symmetry. Ninety-five ground state combination differences were fit to a symmetric top Hamiltonian to give the following ground state rotational constants: B{sup ''}=0.132 081(7) cm{sup -1}, D{sub J}{sup ''}=7.1(7)x10{sup -7} cm{sup -1}, D{sub JK}{sup ''}=-9(2)x10{sup -7} cm{sup -1}, H{sub JJJ}{sup ''}=6(2)x10{sup -10} cm{sup -1}, H{sub JJK}{sup ''}=9(7)x10{sup -10} cm{sup -1}, H{sub JKK}{sup ''}=-1.3(8)x10{sup -10} cm{sup -1}. A total of 190 transitions were fit to determine the upper state spectroscopic constants: v{sub 4}=714.7849(1) cm{sup -1}, B{sup '}=0.129 634(5) cm{sup -1}, {delta}(C-B)=0.001 344 cm{sup -1}, D{sub J}{sup '}=6.4(5)x10{sup -7} cm{sup -1}, D{sub JK}{sup '}=-4.5(6)x10{sup -7} cm{sup -1}, {delta}D{sub K}=2.92(8)x10{sup -6} cm{sup -1}, H{sub JJJ}{sup '}=3(1)x10{sup -10} cm{sup -1}, H{sub JKK}{sup '}=-1.55(6)x10{sup -8} cm{sup -1}; {delta}H{sub KKK}=-4.65(6)x10{sup -8} cm{sup -1}. Furthermore, a perpendicular band centered at 752.7 cm{sup -1} was observed. The band has a rotational line spacing that gives an approximate B{sup ''} value of 0.132 cm{sup -1}; it has been assigned as the E{sub u} symmetry, H-F in-plane libration fundamental of the HF tetramer. Finally, a parallel band was observed at 741.0 cm{sup -1} with B{sup ''}=0.076 cm{sup -1} and has been assigned as the A{sup ''} symmetry, H-F out-of-plane libration fundamental of the HF pentamer. Structural parameters and harmonic vibrational frequencies are estimated from first-principles, correlated MP2 and CCSD(T) calculations. These are the largest calculations performed to date for this system with respect to both orbital basis set and level of electron correlation. The CCSD(T) harmonic frequencies are, in particular

  1. HYDROGEN CONCENTRATIONS DURING STORAGE OF 3013 OXIDE SAMPLES

    SciTech Connect

    Hensel, S.; Askew, N.; Laurinat, J.

    2011-03-14

    As part of a surveillance program intended to ensure the safe storage of plutonium bearing nuclear materials in the Savannah River Site (SRS) K-Area Materials Storage (KAMS), samples of these materials are shipped to Savannah River National Laboratory (SRNL) for analysis. These samples are in the form of solids or powders which will have absorbed moisture. Potentially flammable hydrogen gas is generated due to radiolysis of the moisture. The samples are shipped for processing after chemical analysis. To preclude the possibility of a hydrogen deflagration or detonation inside the shipping containers, the shipping times are limited to ensure that hydrogen concentration in the vapor space of every layer of confinement is below the lower flammability limit of 4 volume percent (vol%). This study presents an analysis of the rate of hydrogen accumulation due to radiolysis and calculation of allowable shipping times for typical KAMS materials.

  2. Effects of hydrogen fluoride on water relations and photosynthesis in White Pine (Pinus strobus) seedlings

    SciTech Connect

    Rakowski, K.J.; Zwiazek, J.J. )

    1991-05-01

    Transpiration, photosynthesis, water potential components and tissue fluoride concentrations were determined in mildly drought stressed 9-week-old seedlings fumigated with HF. Only those seedlings which showed no visible signs of fluoride injury were selected for the measurements. Photosynthesis decreased after 1 and 7 days of fumigation with 2, 4 and 20 ppb HF. A decrease in the transpiration rates has been observed after 2, 7 and 22 days of 0.5 ppb HF treatment and after 2 days of 2 ppb HF treatment. The same treatments which reduced transpiration rates resulted in an increase in osmotic potentials and water potentials. Possible mechanism of HF-induced alterations in seedling water relations by altering stomatal movements is discussed.

  3. Stark, Zeeman, and hyperfine properties of v=0, v=1, and the equilibrium configuration of hydrogen fluoride

    NASA Astrophysics Data System (ADS)

    Bass, Steven M.; DeLeon, Robert L.; Muenter, J. S.

    1987-04-01

    Molecular beam electric resonance spectroscopy has been done on the v=0 and v=1 states of hydrogen fluoride in external electric and magnetic fields. The v=1 state was populated using a color center laser. v=0, v=1, and equilibrium configuration results have been obtained for the HF dipole moment, fluorine and proton spin rotation interactions, fluorine and proton magnetic shielding anisotropies, both direct and indirect spin-spin interactions, rotational magnetic moment, and magnetic susceptibility. All of these properties can be extrapolated to v=2 with high accuracy and to higher states with reasonable confidence. First and second derivatives with respect to internuclear distance have also been obtained for several of these properties. Comparisons of HF and DF dipole moments indicate significant differences arising from Born-Oppenheimer breakdown.

  4. He-Ne laser frequencies near 2.4 microns and their application to hydrogen fluoride detection

    NASA Astrophysics Data System (ADS)

    Eberhardt, J. E.; Pryor, A. W.

    1983-06-01

    Eberhardt and Pryor (1982) have reported that emission near 2.40 microns from an He-Ne laser coincides very closely with the 1R(5) absorption frequency of hydrogen fluoride and may, therefore, be used to monitor the presence of HF in the atmosphere. The mismatch between the center frequency of the laser line and that of the 1R(5) HF absorption line appears to be on the order of 100 MHz and, therefore, is negligible when the HF line is broadened to a width of approximately 1000 MHz in the atmosphere. The absorption cross section (2.0 x 10 to the -18th sq cm/HF molecule in the atmosphere) is sufficient to detect HF at a level of approximately 20 microgram/cu m in a 500 m atmospheric path. It is found that three frequencies near 2.4 microns can be conveniently obtained from an He-Ne laser.

  5. Continuous measurement of peak hydrogen fluoride exposures in aluminum smelter potrooms: instrument development and in-plant evaluation.

    PubMed

    Dando, Neal; Xu, Weizong; Peace, Jon Nathaniel

    2008-02-01

    The aluminum smelting process continuously evolves both sulfur dioxide (SO2) and hydrogen fluoride (HF) gases. The vast majority of these evolved gases are captured by local exhaust ventilation systems and transported to fume treatment centers. Any gas escaping the ventilation systems could create the potential for workplace exposures. Currently, there are no commercially available sensors that are capable of selectively measuring peak concentrations (< 10 sec) of HF in the presence of SO2. This measurement capability is critical for facilitating a better understanding of the etiology of respiratory health effects. This article presents the development and in-plant testing of a portable, tunable diode-based HF sensor that shows equivalent or improved performance relative to NIOSH Method 7902 and is capable of measuring short-term personal peak HF exposure potentials in operating aluminum smelters.

  6. Process for converting magnesium fluoride to calcium fluoride

    DOEpatents

    Kreuzmann, A.B.; Palmer, D.A.

    1984-12-21

    This invention is a process for the conversion of magnesium fluoride to calcium fluoride whereby magnesium fluoride is decomposed by heating in the presence of calcium carbonate, calcium oxide or calcium hydroxide. Magnesium fluoride is a by-product of the reduction of uranium tetrafluoride to form uranium metal and has no known commercial use, thus its production creates a significant storage problem. The advantage of this invention is that the quality of calcium fluoride produced is sufficient to be used in the industrial manufacture of anhydrous hydrogen fluoride, steel mill flux or ceramic applications.

  7. Fluoridation Basics

    MedlinePlus

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Water Fluoridation Basics Recommend on Facebook Tweet Share Compartir ... because of tooth decay. History of Fluoride in Water In the 1930s, scientists examined the relationship between ...

  8. Does fluoride disrupt hydrogen bond network in cationic lipid bilayer? Time-dependent fluorescence shift of Laurdan and molecular dynamics simulations

    SciTech Connect

    Pokorna, Sarka; Jurkiewicz, Piotr; Hof, Martin; Vazdar, Mario; Cwiklik, Lukasz; Jungwirth, Pavel

    2014-12-14

    Time-dependent fluorescence shift (TDFS) of Laurdan embedded in phospholipid bilayers reports on hydration and mobility of the phospholipid acylgroups. Exchange of H{sub 2}O with D{sub 2}O prolongs the lifetime of lipid-water and lipid-water-lipid interactions, which is reflected in a significantly slower TDFS kinetics. Combining TDFS measurements in H{sub 2}O and D{sub 2}O hydrated bilayers with atomistic molecular dynamics (MD) simulations provides a unique tool for characterization of the hydrogen bonding at the acylgroup level of lipid bilayers. In this work, we use this approach to study the influence of fluoride anions on the properties of cationic bilayers composed of trimethylammonium-propane (DOTAP). The results obtained for DOTAP are confronted with those for neutral phosphatidylcholine (DOPC) bilayers. Both in DOTAP and DOPC H{sub 2}O/D{sub 2}O exchange prolongs hydrogen-bonding lifetime and does not disturb bilayer structure. These results are confirmed by MD simulations. TDFS experiments show, however, that for DOTAP this effect is cancelled in the presence of fluoride ions. We interpret these results as evidence that strongly hydrated fluoride is able to steal water molecules that bridge lipid carbonyls. Consequently, when attracted to DOTAP bilayer, fluoride disrupts the local hydrogen-bonding network, and the differences in TDFS kinetics between H{sub 2}O and D{sub 2}O hydrated bilayers are no longer observed. A distinct behavior of fluoride is also evidenced by MD simulations, which show different lipid-ion binding for Cl{sup −} and F{sup −}.

  9. Strong absorption by interstellar hydrogen fluoride: Herschel/HIFI observations of the sight-line to G10.6-0.4 (W31C)

    NASA Astrophysics Data System (ADS)

    Neufeld, D. A.; Sonnentrucker, P.; Phillips, T. G.; Lis, D. C.; de Luca, M.; Goicoechea, J. R.; Black, J. H.; Gerin, M.; Bell, T.; Boulanger, F.; Cernicharo, J.; Coutens, A.; Dartois, E.; Kazmierczak, M.; Encrenaz, P.; Falgarone, E.; Geballe, T. R.; Giesen, T.; Godard, B.; Goldsmith, P. F.; Gry, C.; Gupta, H.; Hennebelle, P.; Herbst, E.; Hily-Blant, P.; Joblin, C.; Kołos, R.; Krełowski, J.; Martín-Pintado, J.; Menten, K. M.; Monje, R.; Mookerjea, B.; Pearson, J.; Perault, M.; Persson, C.; Plume, R.; Salez, M.; Schlemmer, S.; Schmidt, M.; Stutzki, J.; Teyssier, D.; Vastel, C.; Yu, S.; Cais, P.; Caux, E.; Liseau, R.; Morris, P.; Planesas, P.

    2010-07-01

    We report the detection of strong absorption by interstellar hydrogen fluoride along the sight-line to the submillimeter continuum source G10.6-0.4 (W31C). We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1232.4763 GHz J = 1-0 HF transition in the upper sideband of the Band 5a receiver. The resultant spectrum shows weak HF emission from G10.6-0.4 at LSR velocities in the range -10 to -3 km s-1, accompanied by strong absorption by foreground material at LSR velocities in the range 15 to 50 km s-1. The spectrum is similar to that of the 1113.3430 GHz 111-000 transition of para-water, although at some frequencies the HF (hydrogen fluoride) optical depth clearly exceeds that of para-H2O. The optically-thick HF absorption that we have observed places a conservative lower limit of 1.6×1014 cm-2 on the HF column density along the sight-line to G10.6-0.4. Our lower limit on the HF abundance, 6×10-9 relative to hydrogen nuclei, implies that hydrogen fluoride accounts for between ~30% and 100% of the fluorine nuclei in the gas phase along this sight-line. This observation corroborates theoretical predictions that - because the unique thermochemistry of fluorine permits the exothermic reaction of F atoms with molecular hydrogen - HF will be the dominant reservoir of interstellar fluorine under a wide range of conditions. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  10. Novel heterocyclic thiosemicarbazones derivatives as colorimetric and “turn on” fluorescent sensors for fluoride anion sensing employing hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Ashok Kumar, S. L.; Saravana Kumar, M.; Sreeja, P. B.; Sreekanth, A.

    2013-09-01

    Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques.

  11. Vapor-liquid equilibria for hydrogen fluoride + difluoromethane, + 1,1,1,2-tetrafluoroethane, and + 1-chloro-1,2,2,2-tetrafluoromethane at 283.3 and 298.2 K

    SciTech Connect

    Lee, J.; Kim, H.; Lim, J.S.; Kim, J.D.; Lee, Y.Y.

    1996-01-01

    The production of refrigerants involves the separation of multicomponent mixtures containing hydrogen fluoride, hydrogen chloride, and various chlorinated and fluorinated hydrocarbons. Therefore, it is essential to known the phase behavior of these mixtures. Isothermal vapor-liquid equilibria for hydrogen fluoride (HF) + difluoromethane (HFC-32), HF + 1,1,1,2-tetrafluoroethane (HFC-134a), and HF + 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) were measured by the P-T-x method at 283.3 and 298.2 K. Vapor compositions were calculated from these results. Among these systems, the HF + HFC-134a and HF + HCFC-124 systems exhibit minimum boiling azeotropes at both temperatures.

  12. Optimal Fluoridation

    PubMed Central

    Lee, John R.

    1975-01-01

    Optimal fluoridation has been defined as that fluoride exposure which confers maximal cariostasis with minimal toxicity and its values have been previously determined to be 0.5 to 1 mg per day for infants and 1 to 1.5 mg per day for an average child. Total fluoride ingestion and urine excretion were studied in Marin County, California, children in 1973 before municipal water fluoridation. Results showed fluoride exposure to be higher than anticipated and fulfilled previously accepted criteria for optimal fluoridation. Present and future water fluoridation plans need to be reevaluated in light of total environmental fluoride exposure. PMID:1130041

  13. Effectivity of fluoride treatment on hydrogen and corrosion product generation in temporal implants for different magnesium alloys.

    PubMed

    Trinidad, Javier; Arruebarrena, Gurutze; Marco, Iñigo; Hurtado, Iñaki; Sáenz de Argandoña, Eneko

    2013-12-01

    The increasing interest on magnesium alloys relies on their biocompatibility, bioabsorbility and especially on their mechanical properties. Due to these characteristics, magnesium alloys are becoming a promising solution to be used, as temporary implants. However, magnesium alloys must overcome their poor corrosion resistance. This article analyses the corrosion behaviour in phosphate-buffered saline solution of three commercial magnesium alloys (AZ31B, WE43 and ZM21) as well as the influence of fluoride treatment on their corrosion behaviour. It is shown that the corrosion rate of all the alloys is decreased by fluoride treatment. However, fluoride treatment affects each alloy differently.

  14. Novel heterocyclic thiosemicarbazones derivatives as colorimetric and "turn on" fluorescent sensors for fluoride anion sensing employing hydrogen bonding.

    PubMed

    Ashok Kumar, S L; Saravana Kumar, M; Sreeja, P B; Sreekanth, A

    2013-09-01

    Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques. PMID:23714188

  15. Standard addition flow method for potentiometric measurements at low concentration levels: application to the determination of fluoride in food samples.

    PubMed

    Galvis-Sánchez, Andrea C; Santos, João Rodrigo; Rangel, António O S S

    2015-02-01

    A standard addition method was implemented by using a flow manifold able to perform automatically multiple standard additions and in-line sample treatment. This analytical strategy was based on the in-line mixing of sample and standard addition solutions, using a merging zone approach. The flow system aimed to exploit the standard addition method to quantify the target analyte particularly in cases where the analyte concentration in the matrix is below the lower limit of linear response of the detector. The feasibility of the proposed flow configuration was assessed through the potentiometric determination of fluoride in sea salts of different origins and different types of coffee infusions. The limit of quantification of the proposed manifold was 5×10(-6) mol L(-1), 10-fold lower than the lower limit of linear response of the potentiometric detector used. A determination rate of 8 samples h(-1) was achieved considering an experimental procedure based on three standard additions per sample. The main advantage of the proposed strategy is the simple approach to perform multiple standard additions, which can be implemented with other ion selective electrodes, especially in cases when the primary ion is below the lower limit of linear response of the detector.

  16. Hydrogen and fluorine in the surfaces of lunar samples

    NASA Technical Reports Server (NTRS)

    Leich, D. A.; Goldberg, R. H.; Burnett, D. S.; Tombrello, T. A.

    1974-01-01

    The resonant nuclear reaction F-19(p, alpha gamma)O-16 has been used to perform depth-sensitive analyses for both fluorine and hydrogen in lunar samples. The resonance at 0.83 MeV (center-of-mass) in this reaction has been applied to the measurement of the distribution of trapped solar protons in lunar samples to depths up to 0.45 microns. These results are interpreted in terms of terrestrial H2O surface contamination and of a redistribution of the implanted solar H which has been influenced by heavy radiation damage in the surface region. Results are also presented for an experiment to test the penetration of H2O into laboratory glass samples which have been irradiated with O-16 to simulate the radiation-damaged surfaces of lunar glasses. Fluorine determinations have been performed in a 1-micron surface layer on lunar samples using the same F-19(p, alpha gamma)O-16 resonance. The data are discussed from the standpoint that observed fluorine concentrations are a mixture of true lunar fluorine and Teflon contamination.

  17. Hydrogen and fluorine in the surfaces of lunar samples

    NASA Technical Reports Server (NTRS)

    Leich, D. A.; Goldberg, R. H.; Burnett, D. S.; Tombrello, T. A.

    1974-01-01

    The resonant nuclear reaction F-19 (p, alpha gamma)0-16 has been used to perform depth sensitive analyses for both fluorine and hydrogen in lunar samples. The resonance at 0.83 MeV (center-of-mass) in this reaction has been applied to the measurement of the distribution of trapped solar protons in lunar samples to depths of about 1/2 micrometer. These results are interpreted in terms of terrestrial H2O surface contamination and a redistribution of the implanted solar H which has been influenced by heavy radiation damage in the surface region. Results are also presented for an experiment to test the penetration of H2O into laboratory glass samples which have been irradiated with 0-16 to simulate the radiation damaged surfaces of lunar glasses. Fluorine determinations have been performed in a 1 pm surface layer on lunar samples using the same F-19 alpha gamma)0-16 resonance. The data are discussed from the standpoint of lunar fluorine and Teflon contamination.

  18. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods.

  19. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods. PMID:21701196

  20. Three-dimensional distribution of hydrogen fluoride gas toward NGC 6334 I and I(N)

    NASA Astrophysics Data System (ADS)

    van der Wiel, M. H. D.; Naylor, D. A.; Makiwa, G.; Satta, M.; Abergel, A.

    2016-09-01

    Context. The HF molecule has been proposed as a sensitive tracer of diffuse interstellar gas, while at higher densities its abundance could be influenced heavily by freeze-out onto dust grains. Aims: We investigate the spatial distribution of a collection of absorbing gas clouds, some associated with the dense, massive star-forming core NGC 6334 I, and others with diffuse foreground clouds elsewhere along the line of sight. For the former category, we aim to study the dynamical properties of the clouds in order to assess their potential to feed the accreting protostellar cores. Methods: We use far-infrared spectral imaging from the Herschel SPIRE iFTS to construct a map of HF absorption at 243 μm in a 6'× 3.´5 region surrounding NGC 6334 I and I(N). Results: The combination of new mapping that is fully sampled spatially, but is spectrally unresolved with a previous, single-pointing, spectrally resolved HF signature yields a three-dimensional picture of absorbing gas clouds in the direction of NGC 6334. Toward core I, the HF equivalent width matches that of the spectrally resolved observation. At angular separations ≳20'' from core I, the HF absorption becomes weaker, which is consistent with three of the seven components being associated with this dense star-forming envelope. Of the remaining four components, two disappear beyond ~1' distance from the NGC 6334 filament, suggesting that these clouds are spatially associated with the star-forming complex. Our data also implies a lack of gas-phase HF in the envelope of core I(N). Using a simple description of adsorption onto and desorption from dust grain surfaces, we show that the overall lower temperature of the envelope of source I(N) is consistent with freeze-out of HF, while it remains in the gas phase in source I. Conclusions: We use the HF molecule as a tracer of column density in diffuse gas (nH ≈ 102-103cm-3), and find that it may uniquely trace a relatively low-density portion of the gas reservoir

  1. Atomic layer etching of Al2O3 using sequential, self-limiting thermal reactions with Sn(acac)2 and hydrogen fluoride.

    PubMed

    Lee, Younghee; George, Steven M

    2015-02-24

    The atomic layer etching (ALE) of Al2O3 was demonstrated using sequential, self-limiting thermal reactions with tin(II) acetylacetonate (Sn(acac)2) and hydrogen fluoride (HF) as the reactants. The Al2O3 samples were Al2O3 atomic layer deposition (ALD) films grown using trimethylaluminum and H2O. The HF source was HF-pyridine. Al2O3 was etched linearly with atomic level precision versus number of reactant cycles. The Al2O3 ALE was monitored at temperatures from 150 to 250 °C. Quartz crystal microbalance (QCM) studies revealed that the sequential Sn(acac)2 and HF reactions were self-limiting versus reactant exposure. QCM measurements also determined that the mass change per cycle (MCPC) increased with temperature from -4.1 ng/(cm(2) cycle) at 150 °C to -18.3 ng/(cm(2) cycle) at 250 °C. These MCPC values correspond to etch rates from 0.14 Å/cycle at 150 °C to 0.61 Å/cycle at 250 °C based on the Al2O3 ALD film density of 3.0 g/cm(3). X-ray reflectivity (XRR) analysis confirmed the linear removal of Al2O3 and measured an Al2O3 ALE etch rate of 0.27 Å/cycle at 200 °C. The XRR measurements also indicated that the Al2O3 films were smoothed by Al2O3 ALE. The overall etching reaction is believed to follow the reaction Al2O3 + 6Sn(acac)2 + 6HF → 2Al(acac)3 + 6SnF(acac) + 3H2O. In the proposed reaction mechanism, the Sn(acac)2 reactant donates acac to the substrate to produce Al(acac)3. The HF reactant allows SnF(acac) and H2O to leave as reaction products. The thermal ALE of many other metal oxides using Sn(acac)2 or other metal β-diketonates, together with HF, should be possible by a similar mechanism. This thermal ALE mechanism may also be applicable to other materials such as metal nitrides, metal phosphides, metal sulfides and metal arsenides.

  2. Atomic layer etching of Al2O3 using sequential, self-limiting thermal reactions with Sn(acac)2 and hydrogen fluoride.

    PubMed

    Lee, Younghee; George, Steven M

    2015-02-24

    The atomic layer etching (ALE) of Al2O3 was demonstrated using sequential, self-limiting thermal reactions with tin(II) acetylacetonate (Sn(acac)2) and hydrogen fluoride (HF) as the reactants. The Al2O3 samples were Al2O3 atomic layer deposition (ALD) films grown using trimethylaluminum and H2O. The HF source was HF-pyridine. Al2O3 was etched linearly with atomic level precision versus number of reactant cycles. The Al2O3 ALE was monitored at temperatures from 150 to 250 °C. Quartz crystal microbalance (QCM) studies revealed that the sequential Sn(acac)2 and HF reactions were self-limiting versus reactant exposure. QCM measurements also determined that the mass change per cycle (MCPC) increased with temperature from -4.1 ng/(cm(2) cycle) at 150 °C to -18.3 ng/(cm(2) cycle) at 250 °C. These MCPC values correspond to etch rates from 0.14 Å/cycle at 150 °C to 0.61 Å/cycle at 250 °C based on the Al2O3 ALD film density of 3.0 g/cm(3). X-ray reflectivity (XRR) analysis confirmed the linear removal of Al2O3 and measured an Al2O3 ALE etch rate of 0.27 Å/cycle at 200 °C. The XRR measurements also indicated that the Al2O3 films were smoothed by Al2O3 ALE. The overall etching reaction is believed to follow the reaction Al2O3 + 6Sn(acac)2 + 6HF → 2Al(acac)3 + 6SnF(acac) + 3H2O. In the proposed reaction mechanism, the Sn(acac)2 reactant donates acac to the substrate to produce Al(acac)3. The HF reactant allows SnF(acac) and H2O to leave as reaction products. The thermal ALE of many other metal oxides using Sn(acac)2 or other metal β-diketonates, together with HF, should be possible by a similar mechanism. This thermal ALE mechanism may also be applicable to other materials such as metal nitrides, metal phosphides, metal sulfides and metal arsenides. PMID:25604976

  3. A pyrolysis/gas chromatographic method for the determination of hydrogen in solid samples

    NASA Technical Reports Server (NTRS)

    Carr, R. H.; Bustin, R.; Gibson, E. K.

    1987-01-01

    A method is described for the determination of hydrogen in solid samples. The sample is heated under vacuum after which the evolved gases are separated by gas chromatography with a helium ionization detector. The system is calibrated by injecting known amounts of hydrogen, as determined manometrically. The method, which is rapid and reliable, was checked for a variety of lunar soils; the limit of detection is about 10 ng of hydrogen.

  4. Test beam results with a sampling calorimeter of cerium fluoride scintillating crystals and tungsten absorber plates for calorimetry at the HL-LHC

    NASA Astrophysics Data System (ADS)

    Becker, R.; Dissertori, G.; Djambazov, L.; Donegà, M.; Dröge, M.; Haller, C.; Horisberger, U.; Lustermann, W.; Nessi-Tedaldi, F.; Quittnat, M.; Pandolfi, F.; Peruzzi, M.; Schönenberger, M.; Cavallari, F.; Dafinei, I.; Diemoz, M.; D`Imperio, G.; del Re, D.; Gelli, S.; Jorda Lope, C.; Meridiani, P.; Micheli, F.; Nuccetelli, M.; Organtini, G.; Paramatti, R.; Pellegrino, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Soffi, L.; Tabarelli de Fatis, T.; Martelli, A.; Monti, V.; Pastrone, N.; Trapani, P. P.; Candelise, V.; Della Ricca, G.

    2016-07-01

    A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (< 10 % /√{ E }). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors' forward regions during the high luminosity phase of LHC.

  5. Bottled Water and Fluoride

    MedlinePlus

    ... Fluoridation Journal Articles for Community Water Fluoridation 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, ...

  6. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    SciTech Connect

    Bartlett, Neil; Whalen, J. Marc; Chacon, Lisa

    2000-12-12

    A method for fluorinating a carbon compound or cationic carbon compound utilizes a fluorination agent selected from thermodynamically unstable nickel fluorides and salts thereof in liquid anhydrous hydrogen fluoride. The desired carbon compound or cationic organic compound to undergo fluorination is selected and reacted with the fluorination agent by contacting the selected organic or cationic organic compound and the chosen fluorination agent in a reaction vessel for a desired reaction time period at room temperature or less.

  7. Fluoride concentration in drinking water of Karachi city (Pakistan).

    PubMed

    Siddique, Azhar; Mumtaz, Majid; Saied, Sumayya; Karim, Zahida; Zaigham, Nayyer A

    2006-09-01

    The ground and municipal water supply samples of Karachi city were analyzed for their fluoride contents. The fluoride contents in water samples collected from the subsurface and river sources were found below the WHO recommended value for the general health of the people. However, in some industrial areas the groundwater sample showed higher level of fluoride concentration. Continuous monitoring of water resources and cautious fluoridation is suggested to maintain proper status of fluoride concentration in the drinking water.

  8. Hydrogenation Reactions during Pyrolysis-Gas Chromatography/Mass Spectrometry Analysis of Polymer Samples Using Hydrogen Carrier Gas.

    PubMed

    Watanabe, Atsushi; Watanabe, Chuichi; Freeman, Robert R; Teramae, Norio; Ohtani, Hajime

    2016-05-17

    Pyrolysis-gas chromatography/mass spectrometry of polymer samples is studied focusing on the effect of hydrogen (H2) carrier gas on chromatographic and spectral data. The pyrograms and the related mass spectra of high density polyethylene (HDPE), low density polyethylene, and polystyrene (PS) serve to illustrate the differences between the species formed in H2 and the helium environment. Differences in the pyrograms and the spectra are generally thought to be a result of the hydrogenation reaction of the pyrolyzates. From the peak intensity changes in the pyrograms of HDPE and PS, hydrogenation of unsaturated pyrolyzates is concluded to occur when the pyrolysis is done in H2. Moreover, additional hydrogenation of the pyrolyzates occurs in the electron ionization source of a MS detector when H2 is used as a carrier gas. Finally, the applicability of mass spectral libraries to characterize pyrograms obtained in H2 is illustrated using 24 polymers. The effect of the hydrogenation reaction on the library search results is found to be negligible for most polymer samples with polar and nonpolar monomer units. PMID:27125864

  9. NREL Develops Accelerated Sample Activation Process for Hydrogen Storage Materials (Fact Sheet)

    SciTech Connect

    Not Available

    2010-12-01

    This fact sheet describes NREL's accomplishments in developing a new sample activation process that reduces the time to prepare samples for measurement of hydrogen storage from several days to five minutes and provides more uniform samples. Work was performed by NREL's Chemical and Materials Science Center.

  10. Hazardous materials accident report - anhydrous hydrogen fluoride release from NATX 9408, Train No. BNEl3Y at Conrail's Receiving Yard, Elkhart, Indiana, February 4, 1985

    SciTech Connect

    Not Available

    1985-11-27

    At 6:30 a.m., on February 4, 1985, an empty placarded railroad tankcar, containing an estimated 800 gallons of anhydrous hydrogen fluoride, a corrosive liquid, was found leaking in the Consolidated Rail Corporation's Elkhart, Indiana Receiving Yard. During the following 4 hours as local emergency response agencies worked to contain the spill, a vapor cloud formed and traveled approximately 2 1/2 miles affecting nearby residential areas northwest of the yard. A total of 1,500 people within a 1.1-square-mile area adjacent to and northwest of the yard were evacuated for 9 hours as an emergency precaution. Local area hospitals treated 75 persons for minor skin and eye irritations. The National Transportation Safety Board determines that the probable cause of the accident was the decision by Burlington Northern to continue in transportation a tankcar reported to be leaking on February 3, 1985, at its Cicero, Illinois railroad yard. The leak in the tankcar resulted from a failure of the tankcar head at a weld undercut made during its construction. Contributing to the extent of the emergency and the unnecessary endangerment of railroad employees and the surrounding communities was the failure of mechanical inspection and supervisory personnel at both the Burlington Northern Railroad Cicero Yard and the Conrail Elkhart Yard to take prompt, appropriate action once notified of the leak.

  11. Proposed replacement and operation of the anhydrous hydrogen fluoride supply and fluidized-bed reactor system at Building 9212. Draft environmental assessment

    SciTech Connect

    1995-03-01

    The US Department of Energy (DOE) proposes to replace the existing anhydrous hydrogen fluoride (AHF) supply and fluidized-bed reactor systems for the Weapons Grade Highly Enriched Uranium Chemical Recovery and Recycle Facility, Building 9212, which is Iocated within the Y-12 Plant on DOE`s Oak Ridge Reservation in Oak Ridge, Tennessee. The current AHF supply and fluidized-bed reactor systems were designed and constructed more than 40 years ago. Because of their deteriorating condition, the corrosive nature of the materials processed, and the antiquated design philosophy upon which they are based, their long-term reliability cannot be assured. The current AHF supply system cannot mitigate an accidental release of AHF and vents fugitive AHF directly to the atmosphere during operations. the proposed action would reduce the risk of exposing the Y-12 Plant work force, the public, and the environment to an accidental release of AHF and would ensure the continuing ability of the Y-12 Plant to manufacture highly enriched uranium metal and process uranium from retired weapons for storage.

  12. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F.; Sparrow, Robert W.

    1991-01-01

    The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

  13. Growth of hollow nickel fluoride whiskers

    SciTech Connect

    Petrov, S. V.; Orekhov, Yu. F.; Fedorov, P. P.

    2009-07-15

    Hollow nickel fluoride whiskers have been obtained by condensation from the vapor phase onto a platinum substrate in a flow of hydrogen fluoride. Crystals up to 5 mm in length have a square cross section with a 300 {+-} 30-{mu}m side. The wall thickness is 85 {+-} 20 {mu}m.

  14. Xenon fluoride solutions effective as fluorinating agents

    NASA Technical Reports Server (NTRS)

    Hyman, H. H.; Quarterman, L. A.; Sheft, I.

    1967-01-01

    Solutions of xenon fluorides in anhydrous hydrogen fluoride have few disruptive effects and leave a residue consisting of gaseous xenon, which can be recovered and refluorinated. This mild agent can be used with materials which normally must be fluorinated with fluorine alone at high temperatures.

  15. COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

    DOEpatents

    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.

  16. Fluoride in chilies from southwestern china.

    PubMed

    Li, Bo; Li, Shehong; Wang, Mingguo; Liu, Xiaojing; Zheng, Baoshan

    2008-10-01

    The purpose of this research is to investigate the fluoride contents in the chilies from southwest China and other countries in order to calculate the difference in fluoride levels in the fresh chilies. The standard method in China for analysis of fluoride in food (GB/T 5009.18-2003) was applied to determinate the fluoride content in chilies. By determining the fluoride content in 176 fresh chili samples from 77 counties in southwest China and 31 chili samples from other countries, the research not only aims to find the regularity of fluoride distribution in fresh chili, but also to determine the origin of fluoride in fresh chili in China compared with the foreign samples. The geometric mean of fluoride content in the fresh chili was 8.9 mg kg(-1) (dry weight, 176 samples, confidence level: 95%). According to the study on the contents of fluoride in fresh chili, it seems that the fluoride content standard for vegetables in GB2762-2005 in China is inappropriate for chili, and 24.7 mg kg(-1)(dry weight) and 5.2 mg kg(-1) (fresh weight) in recommend as the fluoride contaminated discrimination values for fresh chili.

  17. Neutral hydrogen observations of a large sample of galaxies

    SciTech Connect

    Fisher, J.R.; Tully, R.B.

    1981-10-01

    A sample of 1787 nearby galaxies has been observed in the 21 cm line with the NRAO 91 m and 43 m telescopes and the Bonn 100 m telescope. A total of 1171 galaxies were detected. The radio observations provide an accurate heliocentric velocity, an H I flux, and a line profile width for each detection. Literature optical magnitudes, dimensions, and morphological types are reduced to common systems and tabulated. Intrinsic luminosities, dimensions, H I masses, and total masses are determined, assuming distances derived from redshifts.

  18. Multi-saline sample distillation apparatus for hydrogen isotope analyses : design and accuracy

    USGS Publications Warehouse

    Hassan, Afifa Afifi

    1981-01-01

    A distillation apparatus for saline water samples was designed and tested. Six samples may be distilled simultaneously. The temperature was maintained at 400 C to ensure complete dehydration of the precipitating salts. Consequently, the error in the measured ratio of stable hydrogen isotopes resulting from incomplete dehydration of hydrated salts during distillation was eliminated. (USGS)

  19. The effect of fluoridation and its discontinuation on fluoride profiles in the alveolar bone of rat.

    PubMed

    Ohmi, Kyohei; Nakagaki, Haruo; Tsuboi, Shinji; Okumura, Akihiro; Sugiyama, Tomoko; Thuy, Tran Thu; Robinson, Colin

    2005-10-01

    We investigated the effect of fluoridation and its discontinuation on fluoride content in the alveolar portion of the mandible in rats. Drinking water with three different fluoride contents (0, 50, 100 ppmF) was given to rats for three different periods (4, 13 and 25 weeks). Fluoride concentrations were measured in the crest, the middle, and the apical parts of the alveolar bone and in the body of the mandible. Furthermore, after fluoridated drinking water was given to rats for 4 or 13 weeks, distilled water was given to them for 21 or 12 weeks respectively; and the effect of the discontinuation on fluoride profiles was investigated. Layer samples were analyzed by abrasive microsampling. Fluoride and phosphorus concentrations were determined by ion-specific electrode and colorimetric procedures, respectively. There was an increase in fluoride concentrations in the mandible in proportion to the fluoride content in the drinking water and the duration of fluoridation. After fluoridation was discontinued, fluoride concentrations in the surface layers of the mandible presented a decrease. Among the four different parts of the mandible, the upper part of the alveolar bone and the alveolar crest part presented the highest rates of reduction. The relative reduction rate of fluoride concentration was closely related to the duration of discontinuation. The alveolar crest was affected most by the discontinuation of fluoridation, presenting the greatest reduction.

  20. Fluoride glass: Crystallization, surface tension

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1988-01-01

    Fluoride glass was levitated acoustically in the ACES apparatus on STS-11, and the recovered sample had a different microstructure from samples cooled in a container. Further experiments on levitated samples of fluoride glass are proposed. These include nucleation, crystallization, melting observations, measurement of surface tension of molten glass, and observation of bubbles in the glass. Ground experiments are required on sample preparation, outgassing, and surface reactions. The results should help in the development and evaluation of containerless processing, especially of glass, in the development of a contaminent-free method of measuring surface tensions of melts, in extending knowledge of gas and bubble behavior in fluoride glasses, and in increasing insight into the processing and properties of fluoride glasses.

  1. Fluoride Content in Alcoholic Drinks.

    PubMed

    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. PMID:26475300

  2. Corresponding-states behavior of a dipolar model fluid with variable dispersion interactions and its relevance to the anomalies of hydrogen fluoride.

    PubMed

    Weiss, Volker C; Leroy, Frédéric

    2016-06-14

    More than two decades ago, the elusiveness of a liquid-vapor equilibrium and a corresponding critical point in simulations of the supposedly simple model of dipolar hard spheres came as a surprise to many liquid matter theorists. van Leeuwen and Smit [Phys. Rev. Lett. 71, 3991 (1993)] showed that a minimum of attractive dispersion interactions among the dipolar particles may be needed to observe regular fluid behavior. Here, we adopt their approach and use an only slightly modified model, in which the original point dipole is replaced by a dipole moment produced by charges that are separated in space, to study the influence of dispersion interactions of variable strength on the coexistence and interfacial properties of a polar fluid. The thermophysical properties are discussed in terms of Guggenheim's corresponding-states approach. In this way, the coexistence curve, the critical compressibility factor, the surface tension, Guggenheim's ratio, and modifications of Guldberg's and Trouton's rules (related to the vapor pressure and the enthalpy of vaporization) are analyzed. As the importance of dispersion is decreased, a crossover from simple-fluid behavior to that characteristic of strongly dipolar systems takes place; for some properties, this transition is monotonic, but for others it occurs non-monotonically. For strongly dipolar systems, the reduced surface tension is very low, whereas Guggenheim's ratio and Guldberg's ratio are found to be high. The critical compressibility factor is smaller, and the coexistence curve is wider and more skewed than for simple fluids. For very weak dispersion, liquid-vapor equilibrium is still observable, but the interfacial tension is extremely low and may, eventually, vanish marking the end of the existence of a liquid phase. We discuss the implications of our findings for real fluids, in particular, for hydrogen fluoride.

  3. Corresponding-states behavior of a dipolar model fluid with variable dispersion interactions and its relevance to the anomalies of hydrogen fluoride

    NASA Astrophysics Data System (ADS)

    Weiss, Volker C.; Leroy, Frédéric

    2016-06-01

    More than two decades ago, the elusiveness of a liquid-vapor equilibrium and a corresponding critical point in simulations of the supposedly simple model of dipolar hard spheres came as a surprise to many liquid matter theorists. van Leeuwen and Smit [Phys. Rev. Lett. 71, 3991 (1993)] showed that a minimum of attractive dispersion interactions among the dipolar particles may be needed to observe regular fluid behavior. Here, we adopt their approach and use an only slightly modified model, in which the original point dipole is replaced by a dipole moment produced by charges that are separated in space, to study the influence of dispersion interactions of variable strength on the coexistence and interfacial properties of a polar fluid. The thermophysical properties are discussed in terms of Guggenheim's corresponding-states approach. In this way, the coexistence curve, the critical compressibility factor, the surface tension, Guggenheim's ratio, and modifications of Guldberg's and Trouton's rules (related to the vapor pressure and the enthalpy of vaporization) are analyzed. As the importance of dispersion is decreased, a crossover from simple-fluid behavior to that characteristic of strongly dipolar systems takes place; for some properties, this transition is monotonic, but for others it occurs non-monotonically. For strongly dipolar systems, the reduced surface tension is very low, whereas Guggenheim's ratio and Guldberg's ratio are found to be high. The critical compressibility factor is smaller, and the coexistence curve is wider and more skewed than for simple fluids. For very weak dispersion, liquid-vapor equilibrium is still observable, but the interfacial tension is extremely low and may, eventually, vanish marking the end of the existence of a liquid phase. We discuss the implications of our findings for real fluids, in particular, for hydrogen fluoride.

  4. Corresponding-states behavior of a dipolar model fluid with variable dispersion interactions and its relevance to the anomalies of hydrogen fluoride.

    PubMed

    Weiss, Volker C; Leroy, Frédéric

    2016-06-14

    More than two decades ago, the elusiveness of a liquid-vapor equilibrium and a corresponding critical point in simulations of the supposedly simple model of dipolar hard spheres came as a surprise to many liquid matter theorists. van Leeuwen and Smit [Phys. Rev. Lett. 71, 3991 (1993)] showed that a minimum of attractive dispersion interactions among the dipolar particles may be needed to observe regular fluid behavior. Here, we adopt their approach and use an only slightly modified model, in which the original point dipole is replaced by a dipole moment produced by charges that are separated in space, to study the influence of dispersion interactions of variable strength on the coexistence and interfacial properties of a polar fluid. The thermophysical properties are discussed in terms of Guggenheim's corresponding-states approach. In this way, the coexistence curve, the critical compressibility factor, the surface tension, Guggenheim's ratio, and modifications of Guldberg's and Trouton's rules (related to the vapor pressure and the enthalpy of vaporization) are analyzed. As the importance of dispersion is decreased, a crossover from simple-fluid behavior to that characteristic of strongly dipolar systems takes place; for some properties, this transition is monotonic, but for others it occurs non-monotonically. For strongly dipolar systems, the reduced surface tension is very low, whereas Guggenheim's ratio and Guldberg's ratio are found to be high. The critical compressibility factor is smaller, and the coexistence curve is wider and more skewed than for simple fluids. For very weak dispersion, liquid-vapor equilibrium is still observable, but the interfacial tension is extremely low and may, eventually, vanish marking the end of the existence of a liquid phase. We discuss the implications of our findings for real fluids, in particular, for hydrogen fluoride. PMID:27306012

  5. DFT study of hydrogen fluoride and sulfur trioxide interactions on the surface of Pt-decorated graphene

    NASA Astrophysics Data System (ADS)

    Rad, Ali Shokuhi

    2016-08-01

    In this study, we investigate the adsorption properties of hydrogen florid (HF) and sulfur trioxide (SO3) on the surface of platinum decorated graphene (PtG) using density functional theory. We found one optimized configuration for HF and two ones for SO3 upon adsorption on the surface of PtG. Our result show significant adsorption on PtG with calculated energy adsorption of -73.6 (-54.2 BSSE) kJ/mol for HF at its only position and -172.4 (-144.8 BSSE) and -62.7 (-53.7 BSSE) kJ/mol for SO3 at its two positions; P1 and P2, respectively), whereas there is weak physisorption of these analytes on pristine graphene (PG). Results of charge analyses reveled interesting net charge transfer; while the direction of charge is from HF to PtG, reverse direction is found for SO3 for its two configurations. To deep understand the concept of adsorption properties, we used orbital analyses including density of states for interaction of mentioned analytes on the surface of PtG.

  6. Alimentary fluoride intake in preschool children

    PubMed Central

    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

  7. Conceptual design of a hydrogen storage system for a Mars Sample Return mission

    NASA Astrophysics Data System (ADS)

    Mueller, Paul John, III

    A Mars Sample Return mission concept under consideration by NASA uses carbon dioxide from the Martian atmosphere, in combination with hydrogen brought from Earth, to create oxygen and methane propellants for the return trip. This may allow launch from Earth on a smaller, less expensive launch vehicle. A major engineering challenge for this concept is to design a system that can store the hydrogen during the 8-month trip to Mars. A wide variety of design options was considered, including solid, liquid, or slush hydrogen, tank materials, insulation configurations, etc. A comprehensive computer simulation program was written and used to arrive at a preferred hydrogen storage system conceptual design, optimized in terms of mass, insulation thickness, maximum tank pressure, and tank volume. The feasibility of this concept in terms of total spacecraft mass could not be firmly established; however, it appeared very promising and worthy of further development.

  8. Determination of Fluoride in Toothpaste Using an Ion-Selective Electrode

    ERIC Educational Resources Information Center

    Light, Truman S.; Cappuccino, Carleton C.

    1975-01-01

    Outlines the theory of chemical potentiometry, describes the experimental procedure for free fluoride determination, and presents sample data of fluoride concentration for various brands of toothpaste. (GS)

  9. Fluoride retention in saliva and in dental biofilm after different home-use fluoride treatments.

    PubMed

    Souza, Daniela Correia Cavalcante; Maltz, Marisa; Hashizume, Lina Naomi

    2014-01-01

    This single-blind, randomized, crossover study aimed at assessing the long-term fluoride concentrations in saliva and in dental biofilm after different home-use fluoride treatments. The study volunteers (n = 38) were residents of an area with fluoridated drinking water. They were administered four treatments, each of which lasted for one week: twice-daily placebo dentifrice, twice-daily fluoride dentifrice, twice-daily fluoride dentifrice and once-daily fluoride mouthrinse, and thrice-daily fluoride dentifrice. At the end of each treatment period, samples of unstimulated saliva and dental biofilm were collected 8 h after the last oral hygiene procedure. Fluoride concentrations in saliva and dental biofilm were analyzed using a specific electrode. The fluoride concentrations in saliva and dental biofilm 8 h after the last use of fluoride products did not differ among treatments. The results of this study suggest that treatments with home-use fluoride products have no long-term effect on fluoride concentrations in saliva and in dental biofilm of residents of an area with a fluoridated water supply.

  10. High resolution quantum cascade laser studies of the ν3 band of methyl fluoride in solid para-hydrogen.

    PubMed

    McKellar, A R W; Mizoguchi, Asao; Kanamori, Hideto

    2011-09-28

    Spectra of solid para-H(2) doped with CH(3)F at 1.8 K are studied in the ν(3) region (~1040 cm(-1)) using a quantum cascade laser source. As shown previously, residual ortho-H(2) in the sample (~1000 ppm) gives rise to distinct spectral features due to clusters of the form CH(3)F-(ortho-H(2))(N), with N = 0, 1, 2, 3, etc. Brief annealing at 7 K is found to give narrower spectral lines (≥0.006 cm(-1)) than conventional (5 K) annealing, and causes the N = 3 and 4 lines to fragment into two or more components. The N = 3 line is observed to be particularly stable and persistent. The N = 0 line (no ortho-H(2) neighbors) is resolved into two closely spaced (≈0.007 cm(-1)) components which are assigned to the K = 0 and 1 states of CH(3)F rotating around its C(3v) symmetry axis (ortho- and para-CH(3)F, respectively). Similar K-structure is also evident for other lines. Weak but persistent features ("N = 1/2 lines") are observed mid way between N = 0 and 1.

  11. Silicon oxidation in fluoride solutions

    NASA Technical Reports Server (NTRS)

    Sancier, K. M.; Kapur, V.

    1980-01-01

    Silicon is produced in a NaF, Na2SiF6, and Na matrix when SiF4 is reduced by metallic sodium. Hydrogen is evolved during acid leaching to separate the silicon from the accompanying reaction products, NaF and Na2SiF6. The hydrogen evolution reaction was studied under conditions simulating leaching conditions by making suspensions of the dry silicon powder in aqueous fluoride solutions. The mechanism for the hydrogen evolution is discussed in terms of spontaneous oxidation of silicon resulting from the cooperative effects of (1) elemental sodium in the silicon that reacts with water to remove a protective silica layer, leaving clean reactive silicon, and (2) fluoride in solution that complexes with the oxidized silicon in solution and retards formation of a protective hydrous oxide gel.

  12. Topological analysis of the electron density distribution in perturbed systems. I. Effect of charge on the bond properties of hydrogen fluoride.

    PubMed

    Espinosa, Enrique; Alkorta, Ibon; Mata, Ignasi; Molins, Elies

    2005-07-28

    Within the framework of the molecular orbital (MO) theory, the addition of one electron to the 4sigma antibonding orbital of the neutral (F...H) system or the removal of one electron from its pi nonbonding orbitals, leading to (F...H)- and to (F...H)+, has permitted the investigation of these charge perturbations on the bond properties of the hydrogen fluoride molecule by using the topological analysis of rho(r). For (F...H), (F...H)-, and (F...H)+, the topological and energetic properties calculated at the F...H bond critical point (BCP) have been related to the 3sigma bonding molecular orbital (BMO) distribution, as this orbital is the main contributor to rho(r) at the interatomic surface. The analysis has been carried out at several F...H internuclear distances, ranging from 0.8 to 3.0 A. As far as the BMO distribution results from its interaction with the average Coulomb and exchange potential generated by the charge filling the other MOs, and in particular by the pi and 4sigma electrons, the comparison between the BCP properties calculated for the charged systems and those corresponding to the neutral one permits the interpretation of the differences in terms of the charge perturbation on BMO. Along with the BCP properties of (F...H), (F...H)-, and (F...H)+, the interaction energy magnitudes of these systems have been also calculated within the same range of internuclear distances, indicating that the applied perturbations do not break the F-H bond but soften it, giving rise to the stable species (F-H)- and (F-H)+. Comparing the three systems at their equilibrium geometries, the most stable configuration, which corresponds to the unperturbed (F...H) system, shows the highest quantity and the most locally concentrated charge density distribution, along with the largest total electron energy density magnitude, at the interatomic surface as a consequence of the BMO contraction toward the fluorine nucleus in (F...H)+ and of the BMO expansion toward both nuclei in

  13. Deposition of fluoride on enamel surfaces released from varnishes is limited to vicinity of fluoridation site

    PubMed Central

    Lennon, A. M.; Yakin, M.; Becker, K.; Buchalla, W.; Attin, R.; Wiegand, A.

    2006-01-01

    The aim of the in-situ study was to determine fluoride uptake in non-fluoridated, demineralized enamel after application of fluoride varnishes on enamel samples located at various distances from the non-fluoridated samples. All enamel samples used were demineralized with acidic hydroxyethylcellulose before the experiment. Intra-oral appliances were worn by ten volunteers in three series: (1, Mirafluorid, 0.15% F; 2, Duraphat, 2.3% F and 3, unfluoridated controls) of 6 days each. Each two enamel samples were prepared from 30 bovine incisors. One sample was used for the determination of baseline fluoride content (BFC); the other was treated according to the respective series and fixed in the intra-oral appliance for 6 days. Additionally, from 120 incisors, each four enamel samples were prepared (one for BFC). Three samples (a–c) were placed into each appliance at different sites: (a) directly neighboured to the fluoridated specimen (=next), (b) at 1-cm distance (=1 cm) and (c) in the opposite buccal aspect of the appliance (=opposite). At these sites, new unfluoridated samples were placed at days 1, 3 and 5, which were left in place for 1 day. The volunteers brushed their teeth and the samples with fluoridated toothpaste twice per day. Both the KOH-soluble and structurally bound fluoride were determined in all samples to determine fluoride uptake and were statistically analyzed. One day, after fluoridation with Duraphat, KOH-soluble fluoride uptake in specimen a (=next) was significantly higher compared to the corresponding samples of both the control and Mirafluorid series, which in turn were not significantly different from each other. At all other sites and time points, fluoride uptake in the enamel samples were not different from controls for both fluoride varnishes. Within the first day after application, intra-oral-fluoride release from the tested fluoride varnish Duraphat leads to KOH-soluble fluoride uptake only in enamel samples located in close

  14. MStern Blotting-High Throughput Polyvinylidene Fluoride (PVDF) Membrane-Based Proteomic Sample Preparation for 96-Well Plates.

    PubMed

    Berger, Sebastian T; Ahmed, Saima; Muntel, Jan; Cuevas Polo, Nerea; Bachur, Richard; Kentsis, Alex; Steen, Judith; Steen, Hanno

    2015-10-01

    We describe a 96-well plate compatible membrane-based proteomic sample processing method, which enables the complete processing of 96 samples (or multiples thereof) within a single workday. This method uses a large-pore hydrophobic PVDF membrane that efficiently adsorbs proteins, resulting in fast liquid transfer through the membrane and significantly reduced sample processing times. Low liquid transfer speeds have prevented the useful 96-well plate implementation of FASP as a widely used membrane-based proteomic sample processing method. We validated our approach on whole-cell lysate and urine and cerebrospinal fluid as clinically relevant body fluids. Without compromising peptide and protein identification, our method uses a vacuum manifold and circumvents the need for digest desalting, making our processing method compatible with standard liquid handling robots. In summary, our new method maintains the strengths of FASP and simultaneously overcomes one of the major limitations of FASP without compromising protein identification and quantification. PMID:26223766

  15. Tamarind (Tamarindus indica) fruit shell carbon: A calcium-rich promising adsorbent for fluoride removal from groundwater.

    PubMed

    Sivasankar, V; Rajkumar, S; Murugesh, S; Darchen, A

    2012-07-30

    Tamarindus indica fruit shells (TIFSs) are naturally calcium rich compounds. They were impregnated with ammonium carbonate and then carbonized, leading to ammonium carbonate activated ACA-TIFS carbon. The resulting materials and carbon arising from virgin fruit shells V-TIFS were characterized and assayed as adsorbent for the removal of fluoride anions from groundwater. The fluoride scavenging ability of TIFS carbons was due to naturally dispersed calcium compounds. X-ray diffraction (XRD) showed that TIFS carbon contained a mixture of calcium oxalate and calcium carbonate. Batch studies on the fluoride removal efficiency of TIFS carbons with respect to contact time, pH, initial fluoride concentration, and co-ion interference were conducted. Applicability of various kinetic models (viz., pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich) and sorption isotherms were tested for batch techniques. The fluoride removal capacity of TIFS carbons was found to be 91% and 83% at a pH of 7.05 for V-TIFS and ACA-TIFS carbons, respectively. The practical applicability of TIFS carbons using groundwater samples was approved. The fluoride removal was greater in groundwater without hydrogen carbonate ions than those containing these ions. The characterizations of fluoride unloaded and loaded TIFS carbons were done by SEM and XRD studies.

  16. Dynamics of Fluoride Bioavailability in the Biofilms of Different Oral Surfaces after Amine Fluoride and Sodium Fluoride Application

    PubMed Central

    Naumova, Ella A.; Dickten, Christoph; Jung, Rico; Krauss, Florian; Rübesamen, Henrik; Schmütsch, Katharina; Sandulescu, Tudor; Zimmer, Stefan; Arnold, Wolfgang H.

    2016-01-01

    It was the aim of this study to investigate differences in fluoride bioavailability in different oral areas after the application of amine fluoride (AmF) and sodium fluoride (NaF). The null hypothesis suggested no differences in the fluoride bioavailability. The tongue coating was removed and biofilm samples from the palate, oral floor and cheeks were collected. All subjects brushed their teeth with toothpaste containing AmF or NaF. Specimens were collected before, as well as immediately after and at 30 and 120 minutes after tooth brushing. The fluoride concentration was determined. The area under the curve was calculated for each location and compared statistically. In the tongue coating, fluoride concentration increased faster after NaF application than after AmF application. After 30 minutes, the fluoride concentration decreased and remained stable until 120 minutes after AmF application and returned to baseline after NaF application. The difference between the baseline and the endpoint measurements was statistically significant. The fluoride concentration in the tongue coating remained at a higher level compared with the baseline for up to 120 minutes post-brushing. This may indicate that the tongue coating is a major reservoir for fluoride bioavailability. The results also indicate an unequal fluoride distribution in the oral cavity. PMID:26727989

  17. Method of treating fluoride contaminated wastes

    SciTech Connect

    Davis, P.K.; Kakaria, V.K.

    1988-04-05

    A method for treating spent aluminum smelting potliner material containing fluoride contaminants is described which comprises: adding silica to the material to form a mixture thereof; elevating the temperature of the mixture within the range of 1,000/sup 0/ to 1,700/sup 0/C. to form a slag; providing sufficient silica in the mixture and forming the slag in the presence of sufficient water for pyrohydrolysis conditions resulting in the volatilization of substantially all of the fluoride contaminants mostly in the form of hydrogen fluoride; and cooling the slag remaining after volatilizatiion of substantially all of the fluoride contaminants to produce an insoluble silicate glass-residue containing any remaining portion of the fluoride contaminants in an immobile state.

  18. Analysis of 1-Minute Potentially Available Fluoride from Dentifrice

    PubMed Central

    Carey, Clifton M; Holahan, Erin C; Schmuck, Burton D

    2014-01-01

    Previous reports found that some fluoride-containing dentifrices do not release effective concentrations of fluoride during brushing. Failure to release fluoride can be due to dentifrice matrix components that interfere with the solubilization of the fluoride salts during brushing. A new generation of dentifrices has the capability to precipitate beneficial fluoride salts during tooth brushing. Therefore, a method that assesses the potentially available fluoride during the 1-minute brushing is needed. A new filter-paper absorption method to assess the 1-min bioavailable fluoride concentration was developed to meet this need. This method utilizes coiled filter paper that rapidly absorbs the aqueous phase of the dentifrice slurry followed by centrifugation to recover that fluid for fluoride measurement via fluoride ion-selective electrode. The analytical method was used to successfully determine the total fluoride and 1-min bioavailable fluoride in eight dentifrice products containing sodium fluoride (NaF), disodium monofluorophosphate (Na2FPO3, MFP), stannous fluoride (SnF2), or NaF with amorphous calcium phosphate (NaF + ACP). The results showed that some of the dentifrices tested had significantly lower potentially available fluoride than the total fluoride. For a MFP-containing sample, aged seven years past its expiry date, there was significant reduction in the bioavailable fluoride compared to MFP products that were not aged. Other than the aged MFP and the SnF2-containing samples the bioavailable fluoride for all products tested had at least 80 % of the label fluoride concentration. The filter paper absorption method yielded reproducible results for the products tested with MFP samples showing the largest variations. PMID:25821392

  19. AMORE-HX: a multidimensional optimization of radial enhanced NMR-sampled hydrogen exchange.

    PubMed

    Gledhill, John M; Walters, Benjamin T; Wand, A Joshua

    2009-09-01

    The Cartesian sampled three-dimensional HNCO experiment is inherently limited in time resolution and sensitivity for the real time measurement of protein hydrogen exchange. This is largely overcome by use of the radial HNCO experiment that employs the use of optimized sampling angles. The significant practical limitation presented by use of three-dimensional data is the large data storage and processing requirements necessary and is largely overcome by taking advantage of the inherent capabilities of the 2D-FT to process selective frequency space without artifact or limitation. Decomposition of angle spectra into positive and negative ridge components provides increased resolution and allows statistical averaging of intensity and therefore increased precision. Strategies for averaging ridge cross sections within and between angle spectra are developed to allow further statistical approaches for increasing the precision of measured hydrogen occupancy. Intensity artifacts potentially introduced by over-pulsing are effectively eliminated by use of the BEST approach. PMID:19633974

  20. Fluorescent Sensing of Fluoride in Cellular System

    PubMed Central

    Jiao, Yang; Zhu, Baocun; Chen, Jihua; Duan, Xiaohong

    2015-01-01

    Fluoride ions have the important roles in a lot of physiological activities related with biological and medical system, such as water fluoridation, caries treatment, and bone disease treatment. Great efforts have been made to develop new methods and strategies for F- detection in the past decades. Traditional methods for the detection of F- including ion chromatography, ion-selective electrodes, and spectroscopic techniques have the limitations in the biomedicine research. The fluorescent probes for F- are very promising that overcome some drawbacks of traditional fluoride detection methods. These probes exhibit high selectivity, high sensitivity as well as quick response to the detection of fluoride anions. The review commences with a brief description of photophysical mechanisms for fluorescent probes for fluoride, including photo induced electron transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and excited-state intramolecular proton transfer (ESIPT). Followed by a discussion about common dyes for fluorescent fluoride probes, such as anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, cyanine, and near-infrared (NIR) dyes. We divide the fluorescent probes for fluoride in cellular application systems into nine groups, for example, type of hydrogen bonds, type of cleavage of Si-O bonds, type of Si-O bond cleavage and cylization reactions, etc. We also review the recent reported carriers in the delivery of fluorescent fluoride probes. Seventy-four typical fluorescent fluoride probes are listed and compared in detail, including quantum yield, reaction medium, excitation and emission wavelengths, linear detection range, selectivity for F-, mechanism, and analytical applications. Finally, we discuss the future challenges of the application of fluorescent fluoride probes in cellular system and in vivo. We wish that more and more excellent fluorescent fluoride probes will be developed

  1. The quantification of hydrogen and methane in contaminated groundwater: validation of robust procedures for sampling and quantification.

    PubMed

    Dorgerloh, Ute; Becker, Roland; Theissen, Hubert; Nehls, Irene

    2010-10-01

    A number of currently recommended sampling techniques for the determination of hydrogen in contaminated groundwater were compared regarding the practical proficiency in field campaigns. Key characteristics of appropriate sampling procedures are reproducibility of results, robustness against varying field conditions such as hydrostatic pressure, aquifer flow, and biological activity. Laboratory set-ups were used to investigate the most promising techniques. Bubble stripping with gas sampling bulbs yielded reproducible recovery of hydrogen and methane which could be verified for groundwater sampled in two field campaigns. The methane content of the groundwater was confirmed by analysis of directly pumped samples thus supporting the trueness of the stripping results. Laboratory set-ups and field campaigns revealed that bubble stripping of hydrogen may be restricted to the type of used pump. Concentrations of dissolved hydrogen after bubble stripping with an electrically driven submersible pump were about one order of magnitude higher than those obtained from diffusion sampling. The gas chromatographic determination for hydrogen and methane requires manual injection of gas samples and detection by a pulsed discharge detector (PDD) and allows limits of quantification of 3 nM dissolved hydrogen and 1 µg L⁻¹ dissolved methane in groundwater. The combined standard uncertainty of the bubble stripping and GC/PDD quantification of hydrogen in field samples was 7% at 7.8 nM and 18% for 78 nM. PMID:20730246

  2. Leaf water and plant wax hydrogen isotopes in a European sample network

    NASA Astrophysics Data System (ADS)

    Nelson, D. B.; Kahmen, A.

    2014-12-01

    The hydrogen isotopic composition of plant waxes in sediments is now routinely used as a hydroclimate proxy. This application is based largely on empirical calibrations that have demonstrated continental-scale correlations between source water and lipid hydrogen isotope values. But at smaller spatial scales and for individual locations it is increasingly recognized that factors that modify apparent fractionation between source water and leaf lipid hydrogen isotope values must also be considered. Isotopic enrichment of leaf water during transpiration is key among these secondary factors, and is itself sensitive to changes in hydroclimate. Leaf water enrichment also occurs prior to photosynthetic water uptake, and is therefore independent from cellular-level biomarker synthesis. Recent advances in theory have permitted mechanistic models to be developed that can be used to predict the mean leaf water hydrogen and oxygen isotope composition from readily available meteorological variables. This permits global-scale isoscape maps of leaf water isotopic composition and enrichment above source water to be generated, but these models have not been widely validated at continental spatial scales. We have established a network of twenty-one sites across Europe where we are sampling for leaf-, xylem-, and soil-water isotopes (H and O) at approximately 5-week intervals over the summer growing season. We augment the sample set with weekly to monthly precipitation samples and early- and late-season plant wax lipid samples. Collaborators at each site are conducting the sampling, and most sites are members of the FLUXNET tower network that also record high-resolution meteorological data. We present information on the implementation of the network and preliminary results from the 2014 summer season. The complete dataset will be used to track the evolution of water isotopes from source to leaf water and from leaf water to lipid hydrogen across diverse environments. This will provide

  3. Properties of aluminum-fluoride catalysts prepared by the fluoridation of aluminum oxide with trifluoromethane

    SciTech Connect

    McVicker, G.B.; Kim, C.J.; Eggert, J.J.

    1983-04-01

    High-purity AlF/sub 3/ has been prepared by allowing ..gamma..-Al/sub 2/O/sub 3/ to react with gaseous trifluoromethane at 670-770 K under 101 kPa total pressure. The use of gaseous trifluoromethane is a new, general method for preparing metal fluorides from metal oxides. AlF/sub 3/ prepared using this procedure retained the physical form of the starting ..gamma..-Al/sub 2/O/sub 3/. A 1/16-in. ..gamma..-Al/sub 2/O/sub 3/ extrudate, for example, yielded an AlF/sub 3/ extrudate with comparable physical dimensions and crush strengths. X-Ray diffraction, BET surface area, pore volume, and surface acidity measurements were employed to characterize various AlF/sub 3/ samples. Significant decreases in surface area and pore volume as well as surface acidity occurred upon increasing the concentration of AlF/sub 3/ from 90 to 100%. This behavior presumably results from the fluoridation of residual ..gamma..-Al/sub 2/O/sub 3/. AlF/sub 3/ extrudates were utilized as supports for Pt and Pd catalysts. Specific benzene hydrogenation activities of these catalysts are comparable to those of Pt and Pd on ..gamma..-Al/sub 2/O/sub 3/. In a unique application, Pd/AlF/sub 3/ was used to hydrogenate m-diethylbenzene in superacid (HF/TaF/sub 5/) solution.

  4. How Does Fluoride Work?

    MedlinePlus

    ... Help White House Lunch Recipes How Does Fluoride Work? KidsHealth > For Kids > How Does Fluoride Work? Print A A A Text Size There's fluoride ... even in your water. But how does it work to keep teeth healthy? Let's find out. Fluoride ...

  5. Hydrogen isotopes from source water to leaf lipid in a continental-scale sample network

    NASA Astrophysics Data System (ADS)

    Nelson, Daniel; Kahmen, Ansgar

    2015-04-01

    Sedimentary plant waxes are useful paleoclimate proxies because they are preserved in depositional settings on geologic timescales and the isotopic composition of the hydrogen in these molecules reflects that of the source water available during biosynthesis. This application is based largely on empirical calibrations that have demonstrated continental-scale correlations between source water and lipid hydrogen isotope values. However, the importance of variable net isotopic fractionation between source water and lipid for different species and environmental conditions is increasingly recognized. Isotopic enrichment of leaf water during transpiration is key among these secondary factors, and is itself sensitive to changes in hydroclimate. Leaf water enrichment also occurs prior to photosynthetic water uptake, and is therefore independent from cellular-level biomarker synthesis. Mechanistic models can predict the mean leaf water hydrogen isotope composition from readily available meteorological variables. This permits global-scale isoscape maps of leaf water isotopic composition and enrichment above source water to be generated, but these models have not been widely validated at continental spatial scales. We have established a network of twenty-one sites across Europe where we are sampling for leaf-, xylem-, and soil-water isotopes (H and O) at approximately 5-week intervals over the summer growing season. We augment the sample set with weekly to monthly precipitation samples and early- and late-season plant wax lipid samples. Collaborators at each site are conducting the sampling, and most sites are members of the FLUXNET tower network that also record high-resolution meteorological data. We present information on the implementation of the network and preliminary results from the 2014 summer season. The complete dataset will be used to track the evolution of water isotopes from source to leaf water and from leaf water to lipid hydrogen across diverse environments

  6. Two-dimensional gas chromatography-online hydrogenation for improved characterization of petrochemical samples.

    PubMed

    Potgieter, H; Bekker, R; Govender, A; Rohwer, E

    2016-05-01

    The Fischer-Tropsch (FT) process produces a variety of hydrocarbons over a wide carbon number range and during subsequent product workup a large variety of synthetic fuels and chemicals are produced. The complexity of the product slate obtained from this process is well documented and the high temperature FT (HT-FT) process products are spread over gas, oil and water phases. The characterization of these phases is very challenging even when using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS). Despite the increase in separation power, peak co-elution still occurs when samples containing isomeric compounds are analysed by comprehensive two dimensional GC. The separation of isomeric compounds with the same double bond equivalents is especially difficult since these compounds elute in a similar position on the GC×GC chromatogram and have identical molecular masses and similar fragmentation patterns in their electron ionization (EI) mass spectra. On-line hydrogenation after GC×GC separation is a possible way to distinguish between these isomeric compounds since the number of rings and alkene double bonds can be determined from the mass spectra of the compounds before and after hydrogenation. This paper describes development of a GC×GC method with post column hydrogenation for the determination of the backbone of cyclic/olefinic structures enabling us to differentiate between classes like dienes and cyclic olefins in complex petrochemical streams.

  7. Optimization of source-sample-detector geometries for bulk hydrogen analysis using epithermal neutrons.

    PubMed

    Csikai, J; Dóczi, R

    2009-01-01

    The advantages and limitations of epithermal neutrons in qualification of hydrocarbons via their H contents and C/H atomic ratios have been investigated systematically. Sensitivity of this method and the dimensions of the interrogated regions were determined for various types of hydrogenous samples. Results clearly demonstrate the advantages of direct neutron detection, e.g. by BF(3) counters as compared to the foil activation method in addition to using the hardness of the spectral shape of Pu-Be neutrons to that from a (252)Cf source.

  8. Crystal structure of μ-fluorido-bis-{(η(4)-cyclo-octa-diene)[hexa-fluorido-anti-monato(V)]platinum(II)} hexa-fluorido-anti-monate(V) hydrogen fluoride 0.75-solvate.

    PubMed

    Seppelt, Konrad; Friedemann, Roland

    2016-01-01

    In the complex cation of the binuclear solvated title salt, [Pt2F(SbF6)2(C8H12)2]SbF6·0.75HF, an F atom bridges the two platinum(II) atoms with a bond angle of 123.3 (2)°. The corresponding Pt-F bond lengths are in the range of other fluorine-bridged binuclear platinum(II) complexes. Two of the three SbF6 (-) anions each coordinate with one F atom to one platinum(II) atom. Including the η(4)-bound cyclo-octa-diene (COD) ligands, the overall coordination sphere of each platinum(II) atom is square-planar. The third SbF6 (-) anion is not bound to the complex. Hydrogen fluoride is present in the crystal structure as a solvent disordered over three positions, each with an occupancy of 0.25. F⋯F distances of 2.5512 (7), 2.6076 (8) and 3.2215 (10) Å to surrounding SbF6 (-) anions are indicative of F-H⋯F hydrogen-bonding inter-actions although no H atoms could be localized for the disordered solvent mol-ecules. The resulting hydrogen-bonded network is three-dimensional. PMID:26870575

  9. Fluoride in drinking water and dental fluorosis.

    PubMed

    Mandinic, Zoran; Curcic, Marijana; Antonijevic, Biljana; Carevic, Momir; Mandic, Jelena; Djukic-Cosic, Danijela; Lekic, Charles P

    2010-08-01

    In this study we determined the fluoride content in drinking water and hair of 12-year-old schoolchildren from different Serbian municipalities, i.e. Valjevo, Veliko Gradiste, Kacarevo and Vranjska Banja. The analyses were performed using composite fluoride ion-selective electrode. Average fluoride levels were 0.10, 0.15, 0.79 and 11 ppm in well water, 0.07, 0.10, 0.17 and 0.15 ppm in tap water, 19.3, 21.5, 25.4, and 32.5 ppm in hair samples, in Valjevo, Veliko Gradiste, Kacarevo and Vranjska Banja, respectively. Correlation analysis indicated statistically significant positive relationship between fluoride in wells water and fluoride in hair, for all municipalities: correlation coefficients were 0.54 (p < 0.05), 0.89, 0.97 and 0.99 (p < 0.001), in Vranjska Banja, Valjevo, Veliko Gradiste, and Kacarevo, respectively. Positive correlation was obtained also between fluoride in tap water and hair samples in all regions under the study, with statistical significance only in Valjevo municipality, p < 0.05. Dental examination of schoolchildren confirmed dental fluorosis only in the region of Vranjska Banja. Moreover, in endemic fluorotic region of Vranjska Banja, positive and statistically significant correlations were confirmed between fluoride in well water and dental fluorosis level (r = 0.61; p < 0.01) and additionally between fluoride in hair and dental fluorosis level (0.62; p < 0.01). The primary findings from this study have shown that fluoride content in hair is highly correlated with fluoride content in drinking water and dental fluorosis level, indicating that hair may be regarded as biomaterial of high informative potential in evaluating prolonged exposure to fluorides and to individuate children at risk of fluorosis regardless of the phase of teeth eruption. PMID:20580811

  10. Fluoride and Water (For Parents)

    MedlinePlus

    ... Things to Know About Zika & Pregnancy Fluoride and Water KidsHealth > For Parents > Fluoride and Water Print A ... to 19-year-olds continue Fluoride and the Water Supply For more than 60 years, water fluoridation ...

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

    PubMed Central

    MOIMAZ, Suzely Adas Saliba; SALIBA, Nemre Adas; SALIBA, Orlando; SUMIDA, Doris Hissako; de SOUZA, Neila Paula; CHIBA, Fernando Yamamoto; GARBIN, Cléa Adas Saliba

    2013-01-01

    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. PMID:23559106

  12. Distribution of hydrogen peroxide-dependent reaction in a gelatin sample irradiated by carbon ion beam.

    PubMed

    Matsumoto, Ken-ichiro; Aoki, Ichio; Nakanishi, Ikuo; Matsumoto, Atsuko; Nyui, Minako; Endo, Kazutoyo; Anzai, Kazunori

    2010-01-01

    We investigated the amount and distribution of hydrogen peroxide (H(2)O(2)) generated in a solid gelatin sample irradiated by heavy ion (carbon) beam. We irradiated the gelatin sample, which contained a nitroxyl radical (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, TEMPOL), with a 290-MeV/nucleon carbon beam (~128 Gy). To verify the distribution of H(2)O(2) generation in the irradiated sample, we employed both electron paramagnetic resonance (EPR) spectroscopic and magnetic resonance (MR) imaging methods based on H(2)O(2)-dependent paramagnetic loss of TEMPOL. We obtained a distribution profile of the H(2)O(2)-dependent reaction in the gelatin sample when we irradiated gelatin samples with carbon beams with several different linear energy transfer (LET) values. Because the profiles of oxygen consumption in the gelatin sample measured by L-band EPR oxymetry and of the H(2)O(2)-dependent reaction have almost the same shape, the profile of the H(2)O(2)-dependent reaction can be used as an estimation of the profile of the generation of H(2)O(2). The H(2)O(2) profile in one intact gelatin sample scanned by 7-tesla MR imaging showed a similar shape as a result of the EPR experiment. We obtained several hundreds of micromolars of H(2)O(2) generated in a gelatin sample irradiated by carbon beam when 200 Gy was given at the surface of the sample. H(2)O(2) distribution was almost flat, with only a slight peak just before the end of the beam.

  13. Quantum theory of atoms in molecules/charge-charge flux-dipole flux models for fundamental vibrational intensity changes on H-bond formation of water and hydrogen fluoride

    SciTech Connect

    Silva, Arnaldo F.; Richter, Wagner E.; Bruns, Roy E.; Terrabuio, Luiz A.; Haiduke, Roberto L. A.

    2014-02-28

    The Quantum Theory of Atoms In Molecules/Charge-Charge Flux-Dipole Flux (QTAIM/CCFDF) model has been used to investigate the electronic structure variations associated with intensity changes on dimerization for the vibrations of the water and hydrogen fluoride dimers as well as in the water-hydrogen fluoride complex. QCISD/cc-pVTZ wave functions applied in the QTAIM/CCFDF model accurately provide the fundamental band intensities of water and its dimer predicting symmetric and antisymmetric stretching intensity increases for the donor unit of 159 and 47 km mol{sup −1} on H-bond formation compared with the experimental values of 141 and 53 km mol{sup −1}. The symmetric stretching of the proton donor water in the dimer has intensity contributions parallel and perpendicular to its C{sub 2v} axis. The largest calculated increase of 107 km mol{sup −1} is perpendicular to this axis and owes to equilibrium atomic charge displacements on vibration. Charge flux decreases occurring parallel and perpendicular to this axis result in 42 and 40 km mol{sup −1} total intensity increases for the symmetric and antisymmetric stretches, respectively. These decreases in charge flux result in intensity enhancements because of the interaction contributions to the intensities between charge flux and the other quantities. Even though dipole flux contributions are much smaller than the charge and charge flux ones in both monomer and dimer water they are important for calculating the total intensity values for their stretching vibrations since the charge-charge flux interaction term cancels the charge and charge flux contributions. The QTAIM/CCFDF hydrogen-bonded stretching intensity strengthening of 321 km mol{sup −1} on HF dimerization and 592 km mol{sup −1} on HF:H{sub 2}O complexation can essentially be explained by charge, charge flux and their interaction cross term. Atomic contributions to the intensities are also calculated. The bridge hydrogen atomic contributions alone

  14. A study of fluoride groundwater occurrence in Nathenje, Lilongwe, Malawi

    NASA Astrophysics Data System (ADS)

    Msonda, K. W. M.; Masamba, W. R. L.; Fabiano, E.

    A study was carried out to determine fluoride concentration in groundwaters of Nathenje area situated in Lilongwe District in the central region of Malawi. Water samples were collected from 176 boreholes and shallow wells during different months in 2001 and 2002. Samples were then analysed for fluoride by using a fluoride electrode and an ion selective meter. The results showed that fluoride concentrations for the rainy season varied from <0.5 to 6.98 ± 0.01 mg/l with 52.9% of the boreholes above the World Health Organisation (WHO) maximum permissible limit of 1.5 mg/l. Fluoride concentrations for dry season ranged from <0.5 to 7.02 ± 0.02 mg/l with 50.8% of boreholes above 1.5 mg/l. Fluoride concentrations for the two seasons were significantly different from each other ( p < 0.05). Fluoride data was used to produce a fluoride distribution map. From the map, it was observed that fluoride concentrations in this area followed a pattern. The central part of Nathenje had high fluoride concentration of between 2 and 7.02 mg/l and these high fluoride values seemed to extend eastwards beyond the boundary of the study area. However, the southern and western parts had <1 mg/l of fluoride. The high groundwater fluoride values seem to be associated with the weathered basement complex containing biotite that is a probable source of fluoride. The other suspected sources of fluoride in Nathenje groundwater could be due to the dissolution of hornblende, fluorite and amphibole, which are reported to occur in rocks and soils in this area. There was evidence of dental fluorosis in areas where the fluoride concentration was high.

  15. PRODUCTION OF PLUTONIUM FLUORIDE FROM BISMUTH PHOSPHATE PRECIPITATE CONTAINING PLUTONIUM VALUES

    DOEpatents

    Brown, H.S.; Bohlmann, E.G.

    1961-05-01

    A process is given for separating plutonium from fission products present on a bismuth phosphate carrier. The dried carrier is first treated with hydrogen fluoride at between 500 and 600 deg C whereby some fission product fluorides volatilize away from plutonium tetrafluoride, and nonvolatile fission product fluorides are formed then with anhydrous fluorine at between 400 and 500 deg C. Bismuth and plutonium distill in the form of volatile fluorides away from the nonvolatile fission product fluorides. The bismuth and plutonium fluorides are condensed at below 290 deg C.

  16. Isotopic composition of carbon and hydrogen in some Apollo 14 and 15 lunar samples

    USGS Publications Warehouse

    Friedman, Irving; Hardcastle, Kenneth G.; Gleason, Jim D.

    1974-01-01

    Isotopic composition of carbon and hydrogen in some Apollo 14 and 15 lunar samples was determined by use of a newly constructed combustion line that yields low blanks for CO2 and H2. The results from combustion of fines and breccia from Apollo 14 lunar samples and of fines, breccia, and basalt from Apollo 15 were compared with data obtained by heating samples in vacuo to over 1,350°C. The two techniques gave similar results. Total carbon in the fines ranged from 51 to 110 p/m with a C13 of +12 to -8 per mil (parts per thousand) PDB. The breccias contain 22 to 50p/mcarbon with a C13 of -21 to -25 per mil. The crystalline rock (sample 15555) has a carbon content of about 7 p/m and a C13 of -28 per mil. The total hydrogen in the fines ranges from 66 to 120 p/m with a (D/H) X 10-6 of 39 to 90. The breccias contain 8 to 38p/mH2 with a (D/H) X 10-6 of 103 to 144. The crystalline rock contains about 2 p/m H2 with a (D/H) X 10-6 of about 140. Arguments are presented to show that the contamination by earth materials is not as serious a problem as has been proposed by previous authors.

  17. Hydrogen analysis in solid samples using laser-induced helium plasma at atmospheric pressure

    SciTech Connect

    Pardede, Marincan; Kurniawan, Koo Hendrik; Lie, T.J.; Hedwig, Rinda; Idris, Nasrullah; Kobayashi, Takao; Maruyama, Tadashi; Lee, Yong Inn; Kagawa, Kiichiro; Tjia, May On

    2005-08-15

    A special technique for the modification of laser-induced breakdown spectroscopy (LIBS) has been developed to improve the spectral quality of hydrogen emission from a solid sample in helium gas at atmospheric pressure. In this technique, the plasma was generated by focusing a fundamental Nd-YAG (yttrium aluminum garnet) laser into a surrounding helium gas. The helium atoms excited to their metastable states would then serve to excite the atoms of the solid material vaporized by using another Nd-YAG laser. When properly synchronized, the resulting hydrogen emission line of H I 656.2 nm shows a dramatic improvement of the emission intensity and the spectral quality over what was obtained by conventional LIBS technique. This study further reveals that this improvement is mainly due to the role of the metastable excited state in a helium atom, which allows the delayed detection to be performed at a favorable moment when the charged particles responsible for the strong Stark broadening effect in the plasma have mostly disappeared.

  18. Fluoride content in plaque solids and fluid after ingestion of fluoridated milk.

    PubMed

    Martínez-Mier, Esperanza A; Soto-Rojas, Armando E; Buckley, Christine; Weitz, Andrea; Villa, Alberto; Zero, Domenick T

    2013-09-01

    This study explored differences in dental biofilm solids and fluid fluoride after ingestion of NaF or Na2FPO3 in milk or non-fluoridated milk. Eighteen volunteers ingested 1 mg fluoride in 200 mL of milk or 200 mL of non-fluoridated milk. Biofilm samples were collected at baseline, 30, 60, and 240 min and biofilm solids and fluid were micro-analyzed for fluoride. Analysis of variance was performed and the total delivery, retention, and clearance of fluoride to biofilm solids and fluid were estimated as the area under the curve between 0 and 240 min. No statistically significant differences were found for baseline values. Biofilm fluid fluoride values ranged from 0.11 ± 0.05 to 0.21 ± 0.08 µg F/mL while biofilm solid values ranged from 0.62 ± 0.39 to 1.75 ± 1.16 µg F/g. Biofilm fluid values were significantly lower at 60 min for Na2FPO3 in milk. Clearance profiles for biofilm fluid diverged after the initial 60 min. Na2FPO3 had a smaller area under the curve from 60 to 240 min than NaF. Results of this study indicate that the release and clearance of fluoride in biofilm vary among fluoridation compounds and that the concentrations in biofilm solids and fluid also vary and are not correlated to each other in many cases.

  19. High-pressure hydrogen respiration in hydrothermal vent samples from the deep biosphere

    NASA Astrophysics Data System (ADS)

    Morgan-Smith, D.; Schrenk, M. O.

    2013-12-01

    Cultivation of organisms from the deep biosphere has met with many challenges, chief among them the ability to replicate this extreme environment in a laboratory setting. The maintenance of in situ pressure levels, carbon sources, and gas concentrations are important, intertwined factors which may all affect the growth of subsurface microorganisms. Hydrogen in particular is of great importance in hydrothermal systems, but in situ hydrogen concentrations are largely disregarded in attempts to culture from these sites. Using modified Hungate-type culture tubes (Bowles et al. 2011) within pressure-retaining vessels, which allow for the dissolution of higher concentrations of gas than is possible with other culturing methods, we have incubated hydrothermal chimney and hydrothermally-altered rock samples from the Lost City and Mid-Cayman Rise hydrothermal vent fields. Hydrogen concentrations up to 15 mmol/kg have been reported from Lost City (Kelley et al. 2005), but data are not yet available from the recently-discovered Mid-Cayman site, and the elevated concentration of 30 mmol/kg is being used in all incubations. We are using a variety of media types to enrich for various metabolic pathways including iron and sulfur reduction under anoxic or microaerophilic conditions. Incubations are being carried out at atmospheric (0.1 MPa), in situ (9, 23, or 50 MPa, depending on site), and elevated (50 MPa) pressure levels. Microbial cell concentrations, taxonomic diversity, and metabolic activities are being monitored during the course of these experiments. These experiments will provide insight into the relationships between microbial activities, pressure, and gas concentrations typical of deep biosphere environments. Results will inform further culturing studies from both fresh and archived samples. References cited: Bowles, M.W., Samarkin, V.A., Joye, S.B. 2011. Improved measurement of microbial activity in deep-sea sediments at in situ pressure and methane concentration

  20. Analysis of diffential absorption lidar technique for measurements of anhydrous hydrogen chloride from solid rocket motors using a deuterium fluoride laser

    NASA Technical Reports Server (NTRS)

    Bair, C. H.; Allario, F.

    1977-01-01

    An active optical technique (differential absorption lidar (DIAL)) for detecting, ranging, and quantifying the concentration of anhydrous HCl contained in the ground cloud emitted by solid rocket motors (SRM) is evaluated. Results are presented of an experiment in which absorption coefficients of HCl were measured for several deuterium fluoride (DF) laser transitions demonstrating for the first time that a close overlap exists between the 2-1 P(3) vibrational transition of the DF laser and the 1-0 P(6) absorption line of HCl, with an absorption coefficient of 5.64 (atm-cm) to the -1 power. These measurements show that the DF laser can be an appropriate radiation source for detecting HCl in a DIAL technique. Development of a mathematical computer model to predict the sensitivity of DIAL for detecting anhydrous HCl in the ground cloud is outlined, and results that assume a commercially available DF laser as the radiation source are presented.

  1. Estimation of the fluoride concentrations in human breast milk, cow's milk and infant formulae.

    PubMed

    Rahul, P; Hegde, Amitha M; Munshi, A K

    2003-01-01

    Fluoride has a significant effect on the prevention of dental caries. The major dietary intake of the infants constitutes the breast milk cow's milk and infant milk formulations in which the fluoride contents varies widely. Hence it is important to identify the potential milk source of high fluoride intake in an infant's diet and to evaluate the need for the fluoride supplementation. The aim of the present study was to determine the fluoride concentrations in breast milk, cow's milk, infant formulae and water samples in Mangalore city, India, using fluoride electrode (Orion Model 940900). It was noted that minimal amount of fluoride was found to be present in breast milk and cow's milk samples, while the fluoride content of water samples was found to be below the optimum level. On the contrary the infant formulae were found to have equal or more levels of fluoride.

  2. DPB progress report: Hydrogen uptake capacity for a particular sample of DPB

    SciTech Connect

    Dinh, L N; Schildbach, M A; Maxwell, R S; Balazs, B; McLean II, W

    2004-11-09

    The authors have performed hydrogen uptake to measure the remaining capacity for two DPB pellet samples. The measurements were made with a Cahn microbalance operating at room temperature. The DPB samples were placed inside a quartz boat and the microbalance was then evacuated to a base pressure of 10{sup -4} Torr overnight. This overnight pumping removed volatile contaminants from the DPB pellets prior to the introduction of 600 Torr of N{sub 2} into the microbalance chamber. Next, a leak valve connecting the microbalance with a research grade source of H{sub 2} was opened to add 100 Torr of H{sub 2} on top of the 600 Torr of N{sub 2} already in the microbalance. When the total pressure in the microbalance reached 700 Torr, the H{sub 2} leak valve was not completely shut off but reduced to a very small positive rate. An automatic gate valve connecting the microbalance to a turbo molecular pump was programmed by a controller to keep the total pressure in the microbalance at 700 {+-} 3 Torr. The balance between H{sub 2} consumption due to DPB uptake and H{sub 2} leak rate into the microbalance was such that the gate valve to the turbo molecular pump was only slightly opened by the controller once in a while (a few seconds per few hours) to keep the total pressure constant at 700 Torr.

  3. Fluoride Content of Bottled Drinking Water in Chennai, Tamilnadu

    PubMed Central

    Ravi, Karunya; Rajapandian, K.; Gurunathan, Deepa

    2015-01-01

    Context The optimum level of fluoride in drinking water is 0.7 to 1.2 ppm. Decreased fluoride concentration leads to increased risk of caries and increased concentration can lead to dental or skeletal fluorosis. One crore liters of water is supplied to Chennai and surrounding areas through pouches and bottles which carters about one third of city population. Aim The aim of this study is to determine the fluoride concentration in top 10 bottled waters in Chennai and to check the accuracy of their labelling. Materials and Methods Top selling bottled waters, 6 multinational and 4 Non- multinational brands were selected for the study. Three different batches of each brand were purchased. The labels of the bottled were removed after collecting the details regarding fluoride content. All the bottles were numbered and sent for fluoride content analysis using SPADNS calorimetric method. Results All the brands and batches which were analysed for the study had less than optimal fluoride content and there is a significant variation in fluoride concentration of each brand and among different batches of same brand bottled waters. The range of fluoride level in tested samples was between 0.27 to 0.59. Only one brand’s label had information regarding the fluoride content. Conclusion Standardization of fluoride levels in bottled waters and labelling of fluoride content should become mandatory. PMID:26557612

  4. Hydrogen sensor

    DOEpatents

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  5. Atomic hydrogen emission induced by TEA CO(2) laser bombardment on solid samples at low pressure and its analytical application.

    PubMed

    Idris, Nasrullah; Terai, Sumito; Lie, Tjung Jie; Kurniawan, Hendrik; Kobayashi, Takao; Maruyama, Tadashi; Kagawa, Kiichiro

    2005-01-01

    Hydrogen emission has been studied in laser plasmas by focusing a TEA CO(2) laser (10.6 microm, 500 mJ, 200 ns) on various types of samples, such as glass, quartz, black plastic sheet, and oil on copper plate sub-target. It was found that H(alpha) emission with a narrow spectral width occurs with high efficiency when the laser plasma is produced in the low-pressure region. On the contrary, the conventional well-known laser-induced breakdown spectroscopy (LIBS), which is usually carried out at atmospheric air pressure, cannot be applied to the analysis of hydrogen as an impurity. By combining low-pressure laser-induced plasma spectroscopy with laser surface cleaning, a preliminary quantitative analysis was made on zircaloy pipe samples intentionally doped with hydrogen. As a result, a good linear relationship was obtained between H(alpha) emission intensity and its concentration.

  6. Fluoride concentration in plaque in adolescents after topical application of different fluoride varnishes.

    PubMed

    Sköld-Larsson, K; Modéer, T; Twetman, S

    2000-03-01

    The aim of the study was to measure the fluoride (F) concentration in plaque after a single topical application of different fluoride varnishes with contrasting levels of F. Thirty adolescents (12-17 years) with fixed orthodontic appliances were randomly assigned to one of three groups: Bifluoride (6% F), Duraphat (2.23% F) and Fluor Protector (0.1% F). The varnishes were applied after professional cleaning in one upper quadrant, leaving the opposite quadrant untreated according to the split-mouth technique. Pooled plaque samples from each quadrant were collected at baseline and 3 days, 7 days and 30 days after the varnish treatment, and fluoride was analysed by microdiffusion. All fluoride varnishes increased the fluoride concentration in plaque compared with baseline, and the mean values varied between 23 and 138 ng F/mg after 3 days, depending on varnish F concentration. Compared with the control quadrant, statistically significant elevations were recorded for Bifluoride after 3 days and 7 days and Duraphat after 3 days, while no significant differences were revealed in the Fluor Protector group. The fluoride concentration in plaque was back to baseline levels for all participants in the Duraphat group after 7 days, while some individuals in the Bifluoride and Fluor Protector groups still registered slightly increased levels after 30 days. The results suggest that fluoride varnish treatments resulted in elevated fluoride levels in plaque adjacent to fixed orthodontic appliances for a period of up to 1 week, although different patterns was disclosed for the various brands.

  7. A comparative assessment of fluoride concentration available in saliva using daily prescribed topical fluoride agents

    PubMed Central

    Talwar, Manjit; Tewari, Amrit; Chawla, H. S.; Sachdev, Vinod

    2016-01-01

    Objective: To assess the availability of fluoride concentration in saliva following the use of fluoride mouthrinse and dentifrice. Materials and Methods: The experiment was carried out in 7–15 year-old school children of Chandigarh (n = 90). The children were nonfluoride users. Baseline saliva samples were collected. The subjects were exposed to two test agents, i.e., fluoride mouthrinse (0.05%, 225 ppm F) and dentifrice (1000 ppm F) for 7 days and on the day 8, saliva samples were collected over a 20 hrs period. Wash out period of 31/2 months was there before the subjects were exposed to the second test agent. Fluoride in saliva was estimated using fluoride ion-specific electrode. Written informed consent was taken. Statistical Analysis: Kolmogorov–Smirnov test was applied to test the normality of the variables. Mann–Whitney U-test was used to compare the fluoride concentration available in saliva at respective time intervals subsequent to use of the two test agents. Results: Fluoride concentration was elevated in saliva compared to baseline for both the test agents. Fluoride mouthrinse (0.05% sodium fluoride [NaF]) and dentifrice (1000 ppm monofluorophosphate [MFP]) showed a biphasic clearance. Peak in saliva occurred at 15 mins postuse. Night-time use resulted in higher concentration of fluoride in saliva compared to baseline. There was statistically significantly higher fluoride concentration available in saliva for the dentifrice at 5 hrs, 10 hrs, and 20 hrs postuse (P < 0.05). Conclusion: Subsequent to the use of NaF (0.05%) daily mouthrinse and MFP dentifrice (1000 ppm) the fluoride concentration in saliva remained elevated to a level of 0.12 ppm for mouthrinse and 0.14 ppm for dentifrice compared to baseline (0.03 ppm) up to 20 hrs postuse. The therapeutic window though not yet established but suggested is 0.1–1 ppm for prevention of demineralization, indicating that daily use of fluoride mouthrinse and dentifrice provides fluoride concentration in

  8. Fluoride and Oral Health.

    PubMed

    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.

  9. Fluoride and Oral Health.

    PubMed

    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. PMID:27352462

  10. Exhaustive Metropolis Monte Carlo sampling and analysis of polyalanine conformations adopted under the influence of hydrogen bonds.

    PubMed

    Podtelezhnikov, Alexei A; Wild, David L

    2005-10-01

    We propose a novel Metropolis Monte Carlo procedure for protein modeling and analyze the influence of hydrogen bonding on the distribution of polyalanine conformations. We use an atomistic model of the polyalanine chain with rigid and planar polypeptide bonds, and elastic alpha carbon valence geometry. We adopt a simplified energy function in which only hard-sphere repulsion and hydrogen bonding interactions between the atoms are considered. Our Metropolis Monte Carlo procedure utilizes local crankshaft moves and is combined with parallel tempering to exhaustively sample the conformations of 16-mer polyalanine. We confirm that Flory's isolated-pair hypothesis (the steric independence between the dihedral angles of individual amino acids) does not hold true in long polypeptide chains. In addition to 3(10)- and alpha-helices, we identify a kink stabilized by 2 hydrogen bonds with a shared acceptor as a common structural motif. Varying the strength of hydrogen bonds, we induce the helix-coil transition in the model polypeptide chain. We compare the propensities for various hydrogen bonding patterns and determine the degree of cooperativity of hydrogen bond formation in terms of the Hill coefficient. The observed helix-coil transition is also quantified according to Zimm-Bragg theory. PMID:16049911

  11. Analysis of Material Sample Heated by Impinging Hot Hydrogen Jet in a Non-Nuclear Tester

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Foote, John; Litchford, Ron

    2006-01-01

    A computational conjugate heat transfer methodology was developed and anchored with data obtained from a hot-hydrogen jet heated, non-nuclear materials tester, as a first step towards developing an efficient and accurate multiphysics, thermo-fluid computational methodology to predict environments for hypothetical solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on a multidimensional, finite-volume, turbulent, chemically reacting, thermally radiating, unstructured-grid, and pressure-based formulation. The multiphysics invoked in this study include hydrogen dissociation kinetics and thermodynamics, turbulent flow, convective and thermal radiative, and conjugate heat transfers. Predicted hot hydrogen jet and material surface temperatures were compared with those of measurement. Predicted solid temperatures were compared with those obtained with a standard heat transfer code. The interrogation of physics revealed that reactions of hydrogen dissociation and recombination are highly correlated with local temperature and are necessary for accurate prediction of the hot-hydrogen jet temperature.

  12. AES analysis of barium fluoride thin films

    NASA Astrophysics Data System (ADS)

    Kashin, G. N.; Makhnjuk, V. I.; Rumjantseva, S. M.; Shchekochihin, Ju. M.

    1993-06-01

    AES analysis of thin films of metal fluorides is a difficult problem due to charging and decomposition of such films under electron bombardment. We have developed a simple algorithm for a reliable quantitative AES analysis of metal fluoride thin films (BaF 2 in our work). The relative AES sensitivity factors for barium and fluorine were determined from BaF 2 single-crystal samples. We have investigated the dependence of composition and stability of barium fluoride films on the substrate temperature during film growth. We found that the instability of BaF 2 films grown on GaAs substrates at high temperatures (> 525°C) is due to a loss of fluorine. Our results show that, under the optimal electron exposure conditions, AES can be used for a quantitative analysis of metal fluoride thin films.

  13. Well waters fluoride in Enugu, Nigeria.

    PubMed

    Ogbu, I Si; Okoro, O Io; Ugwuja, E I

    2012-04-01

    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. PMID:23022857

  14. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    Fluoride concentrations in eastern UK rivers (the Humber, Tweed, Wear, Great Ouse and Thames) are described based on information collected within the Land-Ocean Interaction Study (LOIS) and by the Environment Agency (EA) of England and Wales. The results show varied fluoride concentrations across the region, with a range from <0.01 to >10 mg l(-1); and mean, median and range in mean concentrations of 0.30, 0.21 and 0.05-3.38 mg l(-1) (excluding one outlier point), respectively. Within the main rivers and tributaries, the mean fluoride concentration varied from approximately 0.5 to over 2 mg l(-1) and the highest values occurred within the Don basin (Don, Dearne and Rother) and parts of the Trent basin (upper Tame and mid-upper Derbyshire Derwent) in highly industrialised and urbanised areas (Sheffield and Rotherham in the Don basin; Birmingham and Derby on the Trent). For localised inputs to the rivers, fluoride concentrations were slightly higher, and considerably higher in one outlier case. Correspondingly, the other rivers examined typically had mean fluoride concentrations between approximately 0.2 and 0.5 mg l(-1), but fluoride concentrations were lower in the headwater areas. As there is much less information on fluoride levels in upland areas, extensive data collected as part of an acid waters survey are used to show that fluoride concentrations are generally less than 0.1 mg l(-1) for the upland UK. The data are summarised in terms of both fluoride concentrations and flux, and the values are cross-referenced to other determinands collected within LOIS. The high positive correlation with boron and negative correlation with flow show the importance of point source (sewage) inputs of fluoride, while strong positive correlations between fluoride and barium indicate the relative importance of vein mineralisation in the bedrock in supplying fluoride to the waters of the Yorkshire Ouse and its tributaries. There seems to be some process that limits the fluoride

  15. Fluoride in UK rivers.

    PubMed

    Neal, Colin; Neal, Margaret; Davies, Helen; Smith, Jennifer

    2003-10-01

    Fluoride concentrations in eastern UK rivers (the Humber, Tweed, Wear, Great Ouse and Thames) are described based on information collected within the Land-Ocean Interaction Study (LOIS) and by the Environment Agency (EA) of England and Wales. The results show varied fluoride concentrations across the region, with a range from <0.01 to >10 mg l(-1); and mean, median and range in mean concentrations of 0.30, 0.21 and 0.05-3.38 mg l(-1) (excluding one outlier point), respectively. Within the main rivers and tributaries, the mean fluoride concentration varied from approximately 0.5 to over 2 mg l(-1) and the highest values occurred within the Don basin (Don, Dearne and Rother) and parts of the Trent basin (upper Tame and mid-upper Derbyshire Derwent) in highly industrialised and urbanised areas (Sheffield and Rotherham in the Don basin; Birmingham and Derby on the Trent). For localised inputs to the rivers, fluoride concentrations were slightly higher, and considerably higher in one outlier case. Correspondingly, the other rivers examined typically had mean fluoride concentrations between approximately 0.2 and 0.5 mg l(-1), but fluoride concentrations were lower in the headwater areas. As there is much less information on fluoride levels in upland areas, extensive data collected as part of an acid waters survey are used to show that fluoride concentrations are generally less than 0.1 mg l(-1) for the upland UK. The data are summarised in terms of both fluoride concentrations and flux, and the values are cross-referenced to other determinands collected within LOIS. The high positive correlation with boron and negative correlation with flow show the importance of point source (sewage) inputs of fluoride, while strong positive correlations between fluoride and barium indicate the relative importance of vein mineralisation in the bedrock in supplying fluoride to the waters of the Yorkshire Ouse and its tributaries. There seems to be some process that limits the fluoride

  16. Changes in plaque fluoride levels by school-based fluoride rinsing and tablet programs in Bangladesh.

    PubMed

    Hossain, Abu Nasir Mohammad Nazmul; Sampaio, Fabio Correia; von der Fehr, Frithjof Ramm; Arneberg, Pål

    2003-02-01

    The aim of this study was to evaluate the effects of school-based fluoride rinsing and tablet programs on plaque fluoride levels. A total of 42 children (8-9 years) were selected from two neighboring schools in Dhaka, Bangladesh. After caries recordings, vestibular plaque samples from the maxillary central incisors and mandibular first molars were collected and frozen on day 0 (baseline). The subjects of one school (rinsing group, n = 15) rinsed with 0.05% NaF, while those from the other school (tablet group, n = 16) used a 0.5 mg F tablet on the 5 school days during a 3-week period. The surfaces were sampled on the first and last school day every week. The fluoride and protein contents of each sample were analyzed using micro-techniques. The median plaque fluoride levels were 9.1 ppm at baseline in the rinsing group and 2.5 ppm in the tablet group (P < 0.05). This difference could in part be related to reported fluoride toothpaste usage. After 4 days on the fluoride programs, plaque fluoride levels in the rinsing group increased to 27.3, 24.5 and 14.2 ppm in the 3 consecutive weeks. The corresponding values after tablet usage were 8.0, 6.5 and 7.1 ppm, respectively. After 3 days without fluoride during the weekends, levels declined towards baseline values in both groups. Hence, the plaque fluoride levels in 8 to 9-year-old Bangladeshi children were increased by both rinsing and tablet programs, but the effect was not detectable 3 days later.

  17. Arsenic from community water fluoridation: quantifying the effect.

    PubMed

    Peterson, Emily; Shapiro, Howard; Li, Ye; Minnery, John G; Copes, Ray

    2016-04-01

    Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation.

  18. Arsenic from community water fluoridation: quantifying the effect.

    PubMed

    Peterson, Emily; Shapiro, Howard; Li, Ye; Minnery, John G; Copes, Ray

    2016-04-01

    Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation. PMID:27105409

  19. PRODUCTION OF THORIUM FLUORIDE

    DOEpatents

    Zachariasen, W.H.

    1959-08-11

    A process is presented for producing anhydrous thorium fluoride comprising the step of contacting a saturated aqueous solution of thorium nitrate with an aqueous solution of hydrofluoric acid having a concentration of about 45 to 50% by weight at a temperature above 70 deg C whereby anhydrous thorium fluoride precipitates.

  20. Interaction of Pipeline Materials with Molten Fluoride Salts

    NASA Astrophysics Data System (ADS)

    Šimo, Tomáš; Matal, Oldřich; Nesvadba, Lukáś; Dvořák, Vladimír; Kanický, Viktor; Sulovský, Petr; Machát, Jiří

    2007-12-01

    Molten fluoride salts are very promising carriers for the transport of large amounts of heat for example from a high temperature nuclear reactor to a plant which generates hydrogen by chemical processes or from a nuclear reactor to a heat exchanger being a part of the equipment needed to realize the Brayton cycle with a very high power efficiency. Therefore, in the framework of our project, experimental and theoretical investigations of the interactions of fluoride salts as heat carriers needed as high potential and structural materials for pipelines in order to transport heat at temperatures above 600◦C were started. Experimental investigations of Fe-based and Ni-based materials in molten fluoride salts at high temperatures and with different exposure times were performed. Two components salts (LiF-NaF and NaF-NaBF4) and three components salts (LiF-NaF-ZrF4 and LiF-NaF-RbF) were chosen in the experiments. The salt analysis was focussed on the content of metallic elements before and after the exposure of the samples to the salt melts. It was done by inductively coupled plasma-optical emission spectrometry (ICP-OES) and by titrimetric techniques. The thickness of the material zone affected by the salt melts, characterized by an enriched / reduced content of elements in comparison to the mean original content, and the material attacked zone, characterized by very tiny channels or chains of pores or pits formed preferably at grain boundaries, were the subject of the analysis performed by electron microscopy / microprobe techniques. Theoretical models for the transport of elements in the material samples exposed to salt melts using experimental data were also developed.

  1. Fluoride levels in vegetation in the vicinity of the Portsmouth Gaseous Diffusion Plant. Final report

    SciTech Connect

    Jackson, D.R.

    1986-04-01

    Battelle initiated a survey of vegetation samples at new and established sites in the vicinity of the Portsmouth Gaseous Diffision Plant. Forty-nine vegetation samples were collected and analyzed for fluoride. Three samples from inside the plant boundaries contained fluoride in concentrations great enough to be of concern to grazing livestock (>40 ppm). All other samples were below the action level. Fluoride concentrations in vegetation reported by Battelle were somewhat greater than identical samples analyzed by GAT. This differences may be accounted for by the fact that GAT rinsed their samples prior to the analysis for fluoride while Battelle did not. Battelles' samples were not washed because fluoride containing particulates on the surface of vegetation can be readily ingested by livestock and may contribute to the total amount of fluoride absorbed by the livestock. Results of the vegetational survey were not correlated with the deposition pattern modeled by Battelle. Apparently, levels of fluoride in vegetation near the plant are not greatly influenced by plant emissions. Extraneous sources such as dust and other forms of atmospheric fluoride appear to be the predominant influence governing fluoride in vegetation. Results from the fluoride deposition model indicate that a deficiency of sampling points may exist in the northwest sector immediately adjacent to the plant perimeter. The addition of new sampling stations in this area would create closer surveillance of potential fluoride emissions from the plant.

  2. Emissions of fluorides from welding processes.

    PubMed

    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. PMID:26574102

  3. Emissions of fluorides from welding processes.

    PubMed

    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.

  4. Acid demineralization susceptibility of dental enamel submitted to different bleaching techniques and fluoridation regimens.

    PubMed

    Salomão, Dlf; Santos, Dm; Nogueira, Rd; Palma-Dibb, Rg; Geraldo-Martins, Vr

    2014-01-01

    The aim of the current study was to assess the acid demineralization susceptibility of bleached dental enamel submitted to different fluoride regimens. One hundred bovine enamel blocks (6×6×3 mm) were randomly divided into 10 groups (n=10). Groups 1 and 2 received no bleaching. Groups 3 to 6 were submitted to an at-home bleaching technique using 6% hydrogen peroxide (HP; G3 and G4) or 10% carbamide peroxide (CP; G5 and G6). Groups 7 to 10 were submitted to an in-office bleaching technique using 35% HP (G7 and G8) or 35% CP (G9 and G10). During bleaching, a daily fluoridation regimen of 0.05% sodium fluoride (NaF) solution was performed on groups 3, 5, 7, and 9, while weekly fluoridation with a 2% NaF gel was performed on groups 4, 6, 8, and 10. The samples in groups 2 to 10 were pH cycled for 14 consecutive days. The samples from all groups were then assessed by cross-sectional Knoop microhardness at different depths from the outer enamel surface. The average Knoop hardness numbers (KHNs) were compared using one-way analysis of variance and Tukey tests (α=0.05). The comparison between groups 1 and 2 showed that the demineralization method was effective. The comparison among groups 2 to 6 showed the same susceptibility to acid demineralization, regardless of the fluoridation method used. However, the samples from groups 8 and 10 showed more susceptibility to acid demineralization when compared with group 2 (p<0.05). Groups 7 and 9 provided similar results to group 2, but the results of those groups were different when compared with groups 8 and 10. The use of 6% HP and 10% CP associated with daily or weekly fluoridation regimens did not increase the susceptibility of enamel to acid demineralization. However, the use of 35% HP and 35% CP must be associated with a daily fluoridation regimen, otherwise the in-office bleaching makes the bleached enamel more susceptible to acid demineralization.

  5. Fluoride release and uptake capacities of fluoride-releasing restorative materials.

    PubMed

    Attar, Nuray; Turgut, Melek D

    2003-01-01

    Many fluoride-releasing dental materials are being sold on the basis of their cariostatic properties. However, the amount fluoride release of these materials is still uncertain. This study investigated the fluoride release and uptake characteristics of four flowable resin composites (Heliomolar Flow, Tetric Flow, Wave, Perma Flo), one flowable compomer (Dyract flow), one conventional glass ionomer cement mixed with two different powder/liquid ratios (ChemFlex Syringeable and ChemFlex Condensable), one packable resin composite (SureFil), one ion-releasing composite (Ariston pHc) and one resin-modified glass ionomer cement (Vitremer). Seven discs (6-mm diameter and 1.5-mm height) were prepared for each material. Each disc was immersed in 3.5 ml of deionized water within a plastic vial and stored at 37 degrees C. The deionized water was changed every 24 hours and the release of fluoride was measured for 30 days. At the end of this period, the samples were recharged with 2 ml of 1.23% acidulated phosphate fluoride (APF) gel for four minutes. Then, all samples were reassessed for an additional 10 days. The fluoride release of all samples was measured with a specific fluoride electrode and an ionanalyzer. Statistical analyses were conducted using two-way repeated measure ANOVA and Duncan's multiple range tests. For all tested materials, the greatest fluoride release was observed after the first day of the study (p<0.01) but gradually diminished with time. During the test period, Tetric Flow released the lowest amount of fluoride; however, no statistically significant difference was found from Wave and Heliomolar Flow (p>0.05). Ariston pHc released the highest amount of fluoride, followed by ChemFlex Syringeable, Vitremer and ChemFlex Condensable. There were statistically significant differences among these materials (p<0.05). Fluoride release of all materials were significantly increased after the first day following refluoridation and Ariston pHc released the greatest

  6. Evaluation of the direct and diffusion methods for the determination of fluoride content in table salt

    PubMed Central

    Martínez-Mier, E. Angeles; Soto-Rojas, Armando E.; Buckley, Christine M.; Margineda, Jorge; Zero, Domenick T.

    2010-01-01

    Objective The aim of this study was to assess methods currently used for analyzing fluoridated salt in order to identify the most useful method for this type of analysis. Basic research design Seventy-five fluoridated salt samples were obtained. Samples were analyzed for fluoride content, with and without pretreatment, using direct and diffusion methods. Element analysis was also conducted in selected samples. Fluoride was added to ultra pure NaCl and non-fluoridated commercial salt samples and Ca and Mg were added to fluoride samples in order to assess fluoride recoveries using modifications to the methods. Results Larger amounts of fluoride were found and recovered using diffusion than direct methods (96%–100% for diffusion vs. 67%–90% for direct). Statistically significant differences were obtained between direct and diffusion methods using different ion strength adjusters. Pretreatment methods reduced the amount of recovered fluoride. Determination of fluoride content was influenced both by the presence of NaCl and other ions in the salt. Conclusion Direct and diffusion techniques for analysis of fluoridated salt are suitable methods for fluoride analysis. The choice of method should depend on the purpose of the analysis. PMID:20088217

  7. Hydrogen Storage in Diamond Powder Utilizing Plasma NaF Surface Treatment for Fuel Cell Applications

    SciTech Connect

    Leal, David A.; Leal-Quiros, E.; Velez, Angel; Prelas, Mark A.; Gosh, Tushar

    2006-12-04

    Hydrogen Fuel Cells offer the vital solution to the world's socio-political dependence on oil. Due to existing difficulty in safe and efficient hydrogen storage for fuel cells, storing the hydrogen in hydrocarbon compounds such as artificial diamond is a realistic solution. By treating the surface of the diamond powder with a Sodium Fluoride plasma exposure, the surface of the diamond is cleaned of unwanted molecules. Due to fluorine's electro negativity, the diamond powder is activated and ready for hydrogen absorption. These diamond powder pellets are then placed on a graphite platform that is heated by conduction in a high voltage circuit made of tungsten wire. Then, the injection of hydrogen gas into chamber allows the storage of the Hydrogen on the surface of the diamond powder. By neutron bombardment in the nuclear reactor, or Prompt Gamma Neutron Activation Analysis, the samples are examined for parts per million amounts of hydrogen in the sample. Sodium Fluoride surface treatment allows for higher mass percentage of stored hydrogen in a reliable, resistant structure, such as diamond for fuel cells and permanently alters the diamonds terminal bonds for re-use in the effective storage of hydrogen. The highest stored amount utilizing the NaF plasma surface treatment was 22229 parts per million of hydrogen in the diamond powder which amounts to 2.2229% mass increase.

  8. Comparison of in vitro fluoride uptake from whitening toothpastes and a conventional toothpaste in demineralised enamel.

    PubMed

    Altenburger, Markus J; Bernhart, Jasmin; Schicha, Thurid D; Wrbas, Karl-Thomas; Hellwig, Elmar

    2010-01-01

    Studies on the compatibility of abrasives and fluoride compounds deal exclusively with fluoride uptake and remineralization after storing the enamel specimens in a toothpaste-saliva mixture. The influence of brushing on the fluoride uptake when highly abrasive toothpastes are used has hardly been investigated so far. The aim of the present study was to investigate fluoride uptake in initially demineralised dental enamel after storage in, or brushing with, whitening toothpaste slurries, compared to a conventional toothpaste. For this purpose two widely available whitening toothpastes with ionically bound fluoride (sodium fluoride NaF), two with covalently-bound fluoride toothpastes (sodium monofluorophosphate, NaMFP) and a conventional amine fluoride toothpaste (AmF) were compared. The fluoride uptake after use of the AmF toothpaste was shown to be statistically significantly higher than that after application of the NaF toothpastes, which in turn was statistically significantly higher than the uptake resulting from NaMFP application. The fluoride uptake was slightly higher when the enamel samples were brushed with NaF toothpaste, rather than just stored in the respective toothpaste slurry. Brushing with highly abrasive toothpastes did not negatively influence fluoride uptake in demineralised dental enamel. The ionic form of the fluoride in toothpastes appears to be critical for increased fluoride uptake. The acidic components of the AmF toothpaste improved fluoride uptake compared to alkaline NaF toothpastes.

  9. Salivary fluoride levels after use of high-fluoride dentifrice.

    PubMed

    Vale, Glauber Campos; Cruz, Priscila Figueiredo; Bohn, Ana Clarissa Cavalcante Elvas; de Moura, Marcoeli Silva

    2015-01-01

    The aim of the study was to evaluate salivary fluoride (F) availability after toothbrushing with a high-F dentifrice. Twelve adult volunteers took part in this crossover and blind study. F concentration in saliva was determined after brushing with a high-F dentifrice (5000 µg F/g) or with a conventional F concentration dentifrice (1100 µg F/g) followed by a 15 mL distilled water rinse. Samples of nonstimulated saliva were collected on the following times: before (baseline), and immediately after spit (time = 0) and after 1, 2, 3, 4, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min. F analysis was performed with a fluoride-sensitive electrode and the area under curve of F salivary concentration × time (µg F/mL × min(-1)) was calculated. At baseline, no significant difference was found among dentifrices (P > 0.05). After brushing, both dentifrices caused an elevated fluoride level in saliva; however salivary F concentration was significantly higher at all times, when high-F dentifrice was used (P < 0.01). Even after 120 min, salivary F concentration was still higher than the baseline values for both dentifrices (P < 0.001). High-F dentifrice enhanced the bioavailability of salivary F, being an option for caries management in patients with high caries risk.

  10. Geological sources of fluoride and acceptable intake of fluoride in an endemic fluorosis area, southern Iran.

    PubMed

    Battaleb-Looie, Sedigheh; Moore, Farid; Jacks, Gunnar; Ketabdari, Mohammad Reza

    2012-10-01

    The present study is the first attempt to put forward possible source(s) of fluoride in the Dashtestan area, Bushehr Province, southern Iran. In response to reports on the high incidence of dental fluorosis, 35 surface and groundwater samples were collected and analysed for fluoride. The results indicate that dissolved fluoride in the study area is above the maximum permissible limit recommended by the World Health Organization (WHO). An additional 35 soil and rock samples were also collected and analysed for fluoride, and rock samples were subjected to petrographic investigations and X-ray diffraction. The results of these analyses show that the most likely source for fluoride in the groundwater is from clay minerals (chlorite) and micas (muscovite, sericite, and biotite) in the soils and rocks in the area. We also note that due to the high average temperatures all year round and excessive water consumption in the area, the optimum fluoride dose level should be lower than that recommended by the WHO.

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

    USGS Publications Warehouse

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

    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 50mg/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 <1% at low pH values to >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, AlF2+, AlF2+ and AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-, FeF2+, FeF2+, MgF+ and 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. ?? 2011.

  12. Formulation and Characterization of Antibacterial Fluoride-releasing Sealants

    PubMed Central

    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

  13. [Exposure of Poznan inhabitants to fluorides. II. Fluorides in urine and hair of school children].

    PubMed

    Oporowska-Moszyk, K; Seńczuk, W

    1997-01-01

    In view of the plans of fresh water fluoridation in Poznań the necessity arose of obtaining of information about the exposure to fluoride compounds. The reported study was carried out in Poznań and environs. Urine and hair samples of children were obtained. The determinations were done with a ion- selective electrode. The mean fluoride concentrations in urine were between 0.3 and 0.9 mg F-/dm3. The concentration in hair was 2.2 mg F-/g in Poznań and 3.3 mg F-/g in Luboń. These values were, however, not exceeding the acceptable ones. In Luboń the concentrations of fluorides in hair was 50% higher than in Poznań. The authors believe that the possible cause was Fertilizer Chemical Works in that location.

  14. Effect of a fluoride solution on dentinal hypersensitivity.

    PubMed

    Thrash, W J; Jones, D L; Dodds, W J

    1992-12-01

    This two-phase experiment assessed the effects over time of a solution containing 1.09% sodium fluoride, .40% stannous fluoride, and .14% hydrogen fluoride (.717% fluoride solution, DentinBloc) on pain associated with dentinal hypersensitivity. During phase I, 30 subjects demonstrating dentinal hypersensitivity to a blast of cool air were divided into three double blind experimental groups. After baseline data were collected for all subjects, one group was instructed to apply the .717% fluoride solution twice a day. A second group was instructed to apply a gel containing .04% stannous fluoride (Gel-Kam) twice a day. A third group was instructed to apply distilled water. Each subject was assessed at 2, 4, 8, and 16 weeks utilizing the "method of limits" with a standardized, repeatable cold thermal stimulus. The results of a two factor repeated ANOVA indicated that those subjects who applied the .717% fluoride solution reported significantly less sensitivity at the 2-week period than the other groups (P < .05). In addition, those subjects whose solution contained the 0.4% stannous fluoride reported significantly less sensitivity at the 4- to 8-week periods (P < .05). Phase II of the study assessed the .717% fluoride solution on a more precise time course. These included: immediately, 15 minute, 1 day, 1 week and 2 weeks. A one factor repeated ANOVA revealed that this effect presented 15-minute post application (P < .05) and continued throughout the testing periods. It was concluded that the fully active 0.717% fluoride solution was an effective agent in the control of dentinal hypersensitivity after two 1-minute applications.

  15. Fluoride in diet

    MedlinePlus

    ... broken through the gums have changes in the enamel that covers the teeth. Faint white lines or streaks may appear, but ... regarding fluoride intake from reconstituted infant formula and ... Dental Association Council on Scientific Affairs. J Am Dent ...

  16. Survey of fluoride levels in vended water stations.

    PubMed

    Jadav, Urvi G; Archarya, Bhavini S; Velasquez, Gisela M; Vance, Bradley J; Tate, Robert H; Quock, Ryan L

    2014-01-01

    This study sought to measure the fluoride concentration of water derived from vended water stations (VWS) and to identify its clinical implications, especially with regard to caries prevention and fluorosis. VWS and corresponding tap water samples were collected from 34 unique postal zip codes; samples were analyzed in duplicate for fluoride concentration. Average fluoride concentration in VWS water was significantly lower than that of tap water (P < 0.001). Fluoride concentration in the VWS water ranged from <0.01 ppm to 0.04 ppm, with a mean concentration of 0.02 ppm (±0.02 ppm). Patients utilizing VWS as their primary source of drinking water may not be receiving optimal caries preventive benefits; thus dietary fluoride supplementation may be indicated. Conversely, to minimize the risk of fluorosis in infants consuming reconstituted infant formula, water from a VWS may be used. PMID:25184716

  17. Assessment of fluoride contamination in groundwater as precursor for electrocoagulation.

    PubMed

    Sajil Kumar, P J

    2012-07-01

    The Present study was conducted in January 2010, in order to assess the fluoride contamination in the Thirupathur Taluk. The major objective of this study was to locate the vulnerable areas in terms of fluoride contamination. The range of fluoride concentration varied between .26 and 2.75 mg/L. 60 % of the samples were above the permissible limit. Good correlation was observed between pH, Na, HCO(3), CO(3) TDS and NO(3). A negative correlation showed by Ca and K. The results show that Geochemistry of these ions controls the Fluoride concentration in the study area. All the samples exceeded the permissible limit of F was characterized by Na-HCO(3) type of water. A fairly good correlation between F and NO(3) suggest an anthropogenic input of F, mainly from the agricultural fields. Spatial distribution map of Fluoride shows very high concentration in the SW part of the study area.

  18. A study to investigate fluoride contamination and fluoride exposure dose assessment in lateritic zones of West Bengal, India.

    PubMed

    Samal, Alok C; Bhattacharya, Piyal; Mallick, Anusaya; Ali, Md Motakabber; Pyne, Jagadish; Santra, Subhas C

    2015-04-01

    To assess the status of severity of fluoride contamination in lateritic Bankura and Purulia districts of West Bengal, concentrations of fluoride in different water sources and agricultural field soils were investigated. The fluoride content (mg/l) was observed to differ with aquifer depths: 0.19-0.47 in dug wells, 0.01-0.17 in shallow tube wells, and 0.07-1.6 in deep tube wells. Fluoride within the World Health Organization (WHO) prescribed range (1.0-1.5 mg/l) was estimated only in ~17% of the total collected water samples while ~67% showed <0.7 mg/l fluoride and thus may impede in the production and maintenance of healthy teeth and bones of the residents, especially children. Fluoride in water was found to be significantly correlated (r = 0.63) with pH. The exposure dose of fluoride (mg/kg/day) from drinking water in infants, children, and adults was estimated in the ranges 0.02-0.53, 0.01-0.24, and 0.01-0.14, respectively against the standard value of 0.05. A clear risk of dental fluorosis is apparent in infants and children of the study area. The fluoride in soil (55-399 mg/kg) was detected to be significantly correlated with the fluoride content in deep tube wells and soil pH (r = 0.56 and 0.71, respectively). The relationships of soil fluoride with total hardness and that with phosphate were not significant. There is a high possibility of bioaccumulation of fluoride from contaminated soil and water of the study area to cultivated crops. This will enhance the quantity of fluoride intake into human food chain in addition to drinking water pathway. PMID:25408071

  19. A study to investigate fluoride contamination and fluoride exposure dose assessment in lateritic zones of West Bengal, India.

    PubMed

    Samal, Alok C; Bhattacharya, Piyal; Mallick, Anusaya; Ali, Md Motakabber; Pyne, Jagadish; Santra, Subhas C

    2015-04-01

    To assess the status of severity of fluoride contamination in lateritic Bankura and Purulia districts of West Bengal, concentrations of fluoride in different water sources and agricultural field soils were investigated. The fluoride content (mg/l) was observed to differ with aquifer depths: 0.19-0.47 in dug wells, 0.01-0.17 in shallow tube wells, and 0.07-1.6 in deep tube wells. Fluoride within the World Health Organization (WHO) prescribed range (1.0-1.5 mg/l) was estimated only in ~17% of the total collected water samples while ~67% showed <0.7 mg/l fluoride and thus may impede in the production and maintenance of healthy teeth and bones of the residents, especially children. Fluoride in water was found to be significantly correlated (r = 0.63) with pH. The exposure dose of fluoride (mg/kg/day) from drinking water in infants, children, and adults was estimated in the ranges 0.02-0.53, 0.01-0.24, and 0.01-0.14, respectively against the standard value of 0.05. A clear risk of dental fluorosis is apparent in infants and children of the study area. The fluoride in soil (55-399 mg/kg) was detected to be significantly correlated with the fluoride content in deep tube wells and soil pH (r = 0.56 and 0.71, respectively). The relationships of soil fluoride with total hardness and that with phosphate were not significant. There is a high possibility of bioaccumulation of fluoride from contaminated soil and water of the study area to cultivated crops. This will enhance the quantity of fluoride intake into human food chain in addition to drinking water pathway.

  20. Effect of exercise on fluoride metabolism in adult humans: a pilot study.

    PubMed

    V Zohoori, Fatemeh; Innerd, Alison; Azevedo, Liane B; Whitford, Gary M; Maguire, Anne

    2015-01-01

    An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taking a 1-mg Fluoride tablet. After no, light, moderate and vigorous exercise, respectively, the mean (SD) baseline-adjusted i) plasma fluoride concentration was 9.6(6.3), 11.4(6.3), 15.6(7.7) and 14.9(10.0) ng/ml; ii) rate of urinary fluoride excretion over 0-8 h was 46(15), 44(22), 34(17) and 36(17) μg/h; and iii) rate of fluoride renal clearance was 26.5(9.0), 27.2(30.4), 13.1(20.4) and 18.3(34.9) ml/min. The observed trend of a rise in plasma fluoride concentration and decline in rate of fluoride renal clearance with increasing exercise intensity needs to be investigated in a larger trial. This study, which provides the first data on the effect of exercise with different intensities on fluoride metabolism in humans, informs sample size planning for any subsequent definitive trial, by providing a robust estimate of the variability of the effect. PMID:26581340

  1. Effect of exercise on fluoride metabolism in adult humans: a pilot study.

    PubMed

    V Zohoori, Fatemeh; Innerd, Alison; Azevedo, Liane B; Whitford, Gary M; Maguire, Anne

    2015-11-19

    An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taking a 1-mg Fluoride tablet. After no, light, moderate and vigorous exercise, respectively, the mean (SD) baseline-adjusted i) plasma fluoride concentration was 9.6(6.3), 11.4(6.3), 15.6(7.7) and 14.9(10.0) ng/ml; ii) rate of urinary fluoride excretion over 0-8 h was 46(15), 44(22), 34(17) and 36(17) μg/h; and iii) rate of fluoride renal clearance was 26.5(9.0), 27.2(30.4), 13.1(20.4) and 18.3(34.9) ml/min. The observed trend of a rise in plasma fluoride concentration and decline in rate of fluoride renal clearance with increasing exercise intensity needs to be investigated in a larger trial. This study, which provides the first data on the effect of exercise with different intensities on fluoride metabolism in humans, informs sample size planning for any subsequent definitive trial, by providing a robust estimate of the variability of the effect.

  2. Effect of exercise on fluoride metabolism in adult humans: a pilot study

    PubMed Central

    V. Zohoori, Fatemeh; Innerd, Alison; Azevedo, Liane B.; Whitford, Gary M.; Maguire, Anne

    2015-01-01

    An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taking a 1-mg Fluoride tablet. After no, light, moderate and vigorous exercise, respectively, the mean (SD) baseline-adjusted i) plasma fluoride concentration was 9.6(6.3), 11.4(6.3), 15.6(7.7) and 14.9(10.0) ng/ml; ii) rate of urinary fluoride excretion over 0–8 h was 46(15), 44(22), 34(17) and 36(17) μg/h; and iii) rate of fluoride renal clearance was 26.5(9.0), 27.2(30.4), 13.1(20.4) and 18.3(34.9) ml/min. The observed trend of a rise in plasma fluoride concentration and decline in rate of fluoride renal clearance with increasing exercise intensity needs to be investigated in a larger trial. This study, which provides the first data on the effect of exercise with different intensities on fluoride metabolism in humans, informs sample size planning for any subsequent definitive trial, by providing a robust estimate of the variability of the effect. PMID:26581340

  3. Fluorides in the new millennium.

    PubMed

    Padilla, O; Davis, M J

    2001-02-01

    Water fluoridation is known to be the most successful public health measure of the 20th century. More than half a century later, we are still reaping the benefits of fluoridation. We now know that the most important mechanism of fluoride action occurs through daily low-dose exposures. The battle between demineralization and remineralization occurs constantly, and fluoride shifts the balance to the latter. This dynamic, daily process far supersedes the pre-eruptive fluoride incorporation in importance. Fluoride, however, is now available in a variety of very different forms, useful in waging the war on caries. Nevertheless, opponents of this therapeutic agent maintain that its widespread use should be curtailed. Although the benefits of fluoride can no longer be disputed, fluoride supplementation must be supported and approached with consideration of total fluoride exposure. PMID:11280144

  4. Four-sample lactose hydrogen breath test for diagnosis of lactose malabsorption in irritable bowel syndrome patients with diarrhea

    PubMed Central

    Yang, Jian-Feng; Fox, Mark; Chu, Hua; Zheng, Xia; Long, Yan-Qin; Pohl, Daniel; Fried, Michael; Dai, Ning

    2015-01-01

    AIM: To validate 4-sample lactose hydrogen breath testing (4SLHBT) compared to standard 13-sample LHBT in the clinical setting. METHODS: Irritable bowel syndrome patients with diarrhea (IBS-D) and healthy volunteers (HVs) were enrolled and received a 10 g, 20 g, or 40 g dose lactose hydrogen breath test (LHBT) in a randomized, double-blinded, controlled trial. The lactase gene promoter region was sequenced. Breath samples and symptoms were acquired at baseline and every 15 min for 3 h (13 measurements). The detection rates of lactose malabsorption (LM) and lactose intolerance (LI) for a 4SLHBT that acquired four measurements at 0, 90, 120, and 180 min from the same data set were compared with the results of standard LHBT. RESULTS: Sixty IBS-D patients and 60 HVs were studied. The genotype in all participants was C/C-13910. LM and LI detection rates increased with lactose dose from 10 g, 20 g to 40 g in both groups (P < 0.001). 4SLHBT showed excellent diagnostic concordance with standard LHBT (97%-100%, Kappa​​ 0.815-0.942) with high sensitivity (90%-100%) and specificity (100%) at all three lactose doses in both groups. CONCLUSION: Reducing the number of measurements from 13 to 4 samples did not significantly impact on the accuracy of LHBT in health and IBS-D. 4SLHBT is a valid test for assessment of LM and LI in clinical practice. PMID:26140004

  5. Method for decontamination of nickel-fluoride-coated nickel containing actinide-metal fluorides

    DOEpatents

    Windt, Norman F.; Williams, Joe L.

    1983-01-01

    The invention is a process for decontaminating particulate nickel contaminated with actinide-metal fluorides. In one aspect, the invention comprises contacting nickel-fluoride-coated nickel with gaseous ammonia at a temperature effecting nickel-catalyzed dissociation thereof and effecting hydrogen-reduction of the nickel fluoride. The resulting nickel is heated to form a melt and a slag and to effect transfer of actinide metals from the melt into the slag. The melt and slag are then separated. In another aspect, nickel containing nickel oxide and actinide metals is contacted with ammonia at a temperature effecting nickel-catalyzed dissociation to effect conversion of the nickel oxide to the metal. The resulting nickel is then melted and separated as described. In another aspect nickel-fluoride-coated nickel containing actinide-metal fluorides is contacted with both steam and ammonia. The resulting nickel then is melted and separated as described. The invention is characterized by higher nickel recovery, efficient use of ammonia, a substantial decrease in slag formation and fuming, and a valuable increase in the service life of the furnace liners used for melting.

  6. [Ten years of external control over water fluoridation in Chapecó, Santa Catarina State, Brazil].

    PubMed

    Panizzi, Mirvaine; Peres, Marco Aurélio

    2008-09-01

    This study aimed to analyze fluoride concentration in the public water supply in Chapecó, Santa Catarina State, Brazil, from 1995 to 2005 and to assess the effectiveness of a fluoridation quality intervention in 2003. A total of 989 water samples were analyzed. Fluoride concentrations were classified according to three different criteria used in Brazil. The city conducted a political and legal intervention in 2003. The Prais-Winsten procedure was used to evaluate the fluoride concentrations over time. In the ten years, the water fluoridation system showed 46%, 32%, and 43% of adequate samples, depending on the criterion. Prior to the municipal intervention, the proportion of adequate samples was 40%, 26%, and 36%, increasing to 63%, 49%, and 61% after the intervention, according to the three criteria. Fluoride concentration improved after the municipal intervention. On-going surveillance is recommended, including water fluoridation, dental caries, and dental fluorosis.

  7. Groundwater fluoride enrichment in an active rift setting: Central Kenya Rift case study.

    PubMed

    Olaka, Lydia A; Wilke, Franziska D H; Olago, Daniel O; Odada, Eric O; Mulch, Andreas; Musolff, Andreas

    2016-03-01

    Groundwater is used extensively in the Central Kenya Rift for domestic and agricultural demands. In these active rift settings groundwater can exhibit high fluoride levels. In order to address water security and reduce human exposure to high fluoride in drinking water, knowledge of the source and geochemical processes of enrichment are required. A study was therefore carried out within the Naivasha catchment (Kenya) to understand the genesis, enrichment and seasonal variations of fluoride in the groundwater. Rocks, rain, surface and groundwater sources were sampled for hydrogeochemical and isotopic investigations, the data was statistically and geospatially analyzed. Water sources have variable fluoride concentrations between 0.02-75 mg/L. 73% exceed the health limit (1.5mg/L) in both dry and wet seasons. F(-) concentrations in rivers are lower (0.2-9.2mg/L) than groundwater (0.09 to 43.6 mg/L) while saline lake waters have the highest concentrations (0.27-75 mg/L). The higher values are confined to elevations below 2000 masl. Oxygen (δ(18)O) and hydrogen (δD) isotopic values range from -6.2 to +5.8‰ and -31.3 to +33.3‰, respectively, they are also highly variable in the rift floor where they attain maximum values. Fluoride base levels in the precursor vitreous volcanic rocks are higher (between 3750-6000 ppm) in minerals such as cordierite and muscovite while secondary minerals like illite and kaolinite have lower remnant fluoride (<1000 ppm). Thus, geochemical F(-) enrichment in regional groundwater is mainly due to a) rock alteration, i.e. through long residence times and natural discharge and/or enhanced leakages of deep seated geothermal water reservoirs, b) secondary concentration fortification of natural reservoirs through evaporation, through reduced recharge and/or enhanced abstraction and c) through additional enrichment of fluoride after volcanic emissions. The findings are useful to help improve water management in Naivasha as well as similar

  8. Groundwater fluoride enrichment in an active rift setting: Central Kenya Rift case study.

    PubMed

    Olaka, Lydia A; Wilke, Franziska D H; Olago, Daniel O; Odada, Eric O; Mulch, Andreas; Musolff, Andreas

    2016-03-01

    Groundwater is used extensively in the Central Kenya Rift for domestic and agricultural demands. In these active rift settings groundwater can exhibit high fluoride levels. In order to address water security and reduce human exposure to high fluoride in drinking water, knowledge of the source and geochemical processes of enrichment are required. A study was therefore carried out within the Naivasha catchment (Kenya) to understand the genesis, enrichment and seasonal variations of fluoride in the groundwater. Rocks, rain, surface and groundwater sources were sampled for hydrogeochemical and isotopic investigations, the data was statistically and geospatially analyzed. Water sources have variable fluoride concentrations between 0.02-75 mg/L. 73% exceed the health limit (1.5mg/L) in both dry and wet seasons. F(-) concentrations in rivers are lower (0.2-9.2mg/L) than groundwater (0.09 to 43.6 mg/L) while saline lake waters have the highest concentrations (0.27-75 mg/L). The higher values are confined to elevations below 2000 masl. Oxygen (δ(18)O) and hydrogen (δD) isotopic values range from -6.2 to +5.8‰ and -31.3 to +33.3‰, respectively, they are also highly variable in the rift floor where they attain maximum values. Fluoride base levels in the precursor vitreous volcanic rocks are higher (between 3750-6000 ppm) in minerals such as cordierite and muscovite while secondary minerals like illite and kaolinite have lower remnant fluoride (<1000 ppm). Thus, geochemical F(-) enrichment in regional groundwater is mainly due to a) rock alteration, i.e. through long residence times and natural discharge and/or enhanced leakages of deep seated geothermal water reservoirs, b) secondary concentration fortification of natural reservoirs through evaporation, through reduced recharge and/or enhanced abstraction and c) through additional enrichment of fluoride after volcanic emissions. The findings are useful to help improve water management in Naivasha as well as similar

  9. Method for converting UF5 to UF4 in a molten fluoride salt

    DOEpatents

    Bennett, Melvin R.; Bamberger, Carlos E.; Kelmers, A. Donald

    1977-01-01

    The reduction of UF.sub.5 to UF.sub.4 in a molten fluoride salt by sparging with hydrogen is catalyzed by metallic platinum. The reaction is also catalyzed by platinum alloyed with gold reaction equipment.

  10. Comparison of two stable hydrogen isotope-ratio measurement techniques on Antarctic surface-water and ice samples

    USGS Publications Warehouse

    Hopple, J.A.; Hannon, J.E.; Coplen, T.B.

    1998-01-01

    A comparison of the new hydrogen isotope-ratio technique of Vaughn et al. ([Vaughn, B.H., White, J.W.C., Delmotte, M., Trolier, M., Cattani, O., Stievenard, M., 1998. An automated system for hydrogen isotope analysis of water. Chem. Geol. (Isot. Geosci. Sect.), 152, 309-319]; the article immediately preceding this article) for the analysis of water samples utilizing automated on-line reduction by elemental uranium showed that 94% of 165 samples of Antarctic snow, ice, and stream water agreed with the ??2H values determined by H2-H2O platinum equilibration, exhibiting a bias of +0.5??? and a 2 - ?? variation of 1.9???. The isotopic results of 10 reduction technique samples, however, gave ??2H values that differed by 3.5??? or more, and were too negative by as much as 5.4??? and too positive by as much as 4.9??? with respect to those determined using the platinum equilibration technique.

  11. The stability of hydrogen ion and specific conductance in filtered wet-deposition samples stored at ambient temperatures

    USGS Publications Warehouse

    Gordon, J.D.; Schroder, L.J.; Morden-Moore, A. L.; Bowersox, V.C.

    1995-01-01

    Separate experiments by the U.S. Geological Survey (USGS) and the Illinois State Water Survey Central Analytical Laboratory (CAL) independently assessed the stability of hydrogen ion and specific conductance in filtered wet-deposition samples stored at ambient temperatures. The USGS experiment represented a test of sample stability under a diverse range of conditions, whereas the CAL experiment was a controlled test of sample stability. In the experiment by the USGS, a statistically significant (?? = 0.05) relation between [H+] and time was found for the composited filtered, natural, wet-deposition solution when all reported values are included in the analysis. However, if two outlying pH values most likely representing measurement error are excluded from the analysis, the change in [H+] over time was not statistically significant. In the experiment by the CAL, randomly selected samples were reanalyzed between July 1984 and February 1991. The original analysis and reanalysis pairs revealed that [H+] differences, although very small, were statistically different from zero, whereas specific-conductance differences were not. Nevertheless, the results of the CAL reanalysis project indicate there appears to be no consistent, chemically significant degradation in sample integrity with regard to [H+] and specific conductance while samples are stored at room temperature at the CAL. Based on the results of the CAL and USGS studies, short-term (45-60 day) stability of [H+] and specific conductance in natural filtered wet-deposition samples that are shipped and stored unchilled at ambient temperatures was satisfactory.

  12. Fluoride in Ceylon tea and its implications to dental health.

    PubMed

    Chandrajith, Rohana; Abeypala, Uthpala; Dissanayake, C B; Tobschall, H J

    2007-10-01

    The purpose of this study was to assess the fluoride content of Ceylon Tea, which is a popular beverage throughout the world. The fluoride content of tea infusions prepared from different grades of tea leaves collected from different parts of the tea-growing regions (25 samples) of Sri Lanka was measured using a fluoride-selective electrode. Fluoride leaching was found to vary from 0.32 to 1.69 mg F/l, but there were no significant differences in terms of fluoride leaching between tea from different tea-growing regions or between tea of different grades. Dental fluorosis is widespread throughout the dry zone of Sri Lanka, and drinking water has traditionally been considered to be the main contributory factor to the development of fluorosis. However, diet, the consumption of tea in particular, may also contribute to the manifestation of dental diseases.

  13. Ion chromatography detection of fluoride in calcium carbonate.

    PubMed

    Lefler, Jamie E; Ivey, Michelle M

    2011-09-01

    Fluoride in aquatic systems is increasing due to anthropogenic pollution, but little is known about how this fluoride affects organisms that live in and around aquatic habitats. Fluoride can bioaccumulate in structures comprised of calcium carbonate, such as shells and skeletons of both freshwater and saltwater species as diverse as snails, corals, and coccolithophorid algae. In this article, ion chromatography (IC) techniques are developed to detect and quantify fluoride in a matrix of calcium carbonate. Solid samples are dissolved in hydrochloric acid, pretreated to remove the majority of the chloride ions, and then analyzed using IC. With these methods, the 3σ limit of detection is 0.2 mg of fluoride/kg of calcium carbonate. PMID:21859530

  14. Assessment of groundwater quality with respect to fluoride.

    PubMed

    Salve, P R; Maurya, A; Kumbhare, P S; Ramteke, D S; Wate, S R

    2008-09-01

    The study was conducted in the summer season (April-May 2007). The fluoride concentration along with physico-chemical parameters in ground water samples was determined in various villages of Kadi tehsil at Mehsana district of Gujarat state (India), since in most of the villages it is the only source of drinking water. The fluoride concentrations in these villages varied from 0.94 to 2.81 mg/L (1.37+/-0.56) with highest fluoride level at Visalpur (2.08 mg/L) and lowest at Adaraj (0.91 mg/L). There was found a positive correlation of pH with fluoride and a negative relationship of fluoride with bicarbonate which is generally observed in deep ground water.

  15. Fluoride in the UK diet.

    PubMed

    Ruxton, Carrie

    2014-08-12

    Fluoride is a naturally occurring mineral that can be obtained from foods and fluids originating from soils containing fluoride, as well as by drinking water that has been fluoridated. While consuming adequate fluoride intake can deliver benefits for dental and bone health, there have been concerns that excessive fluoride intake could lead to dental fluorosis, or even cause harm to bones. This article considers the balance of evidence in this area, and discusses the benefits and potential risks of fluoride in the UK diet. The role of tea as a major contributor to normal fluoride intake is highlighted, alongside some positive implications of this. Information is also provided to help nurses and midwives communicate the latest advice and guidance on fluoride to their patients. PMID:25095960

  16. Fluoride in the UK diet.

    PubMed

    Ruxton, Carrie

    2014-08-12

    Fluoride is a naturally occurring mineral that can be obtained from foods and fluids originating from soils containing fluoride, as well as by drinking water that has been fluoridated. While consuming adequate fluoride intake can deliver benefits for dental and bone health, there have been concerns that excessive fluoride intake could lead to dental fluorosis, or even cause harm to bones. This article considers the balance of evidence in this area, and discusses the benefits and potential risks of fluoride in the UK diet. The role of tea as a major contributor to normal fluoride intake is highlighted, alongside some positive implications of this. Information is also provided to help nurses and midwives communicate the latest advice and guidance on fluoride to their patients.

  17. Private Well Water and Fluoride

    MedlinePlus

    ... from my well has less than the recommended level of fluoride for preventing tooth decay? The recommended ... if the water from my well has fluoride levels that are higher than the recommended level for ...

  18. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    DOEpatents

    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.

  19. Techniques for the analysis of gases sequentially released from lunar samples

    NASA Technical Reports Server (NTRS)

    Desmarais, D. J.; Hayes, J. M.; Meinschein, W. G.

    1973-01-01

    Description of two methods for the analysis of light gases that are sequentially evolved from 2 to 10 mg of lunar sample. A hydrofluoric acid hydrolysis of lunar material is achieved by repeated exposure of the sample to hydrogen fluoride. In the second technique, gases are evolved from lunar samples by the stepwise heating of these samples to 1400 C. The gases evolved by either hydrolysis or pyrolysis are analyzed in a gas chromatographic system using a helium ionization detector. The sensitivities of this detector for the gases, as analyzed, range from 20 picograms/sec for hydrogen to 0.2 picogram/sec for carbon dioxide.

  20. Fluctuation of fluoride concentrations in drinking waters: a collaborative study.

    PubMed

    Larsen, M J; Fejerskov, O; Bojen, O; Senderowitz, F; Lambrou, D; Manji, F; Hobdell, M

    1989-06-01

    The aim of this study was to describe the variations with time in the concentrations of fluoride in drinking water sources in Greenland, Kenya, Greece, Denmark and Ireland. Water samples were collected monthly and shipped to laboratories in Aarhus for electrometric analyses. In Narssaq, Greenland the fluoride concentration of a single piped water supply ranged from 0.3 to 2.8 ppm, the variations being related to climate, precipitation and temperature over the year. Water from the Athi River, Kenya had a fluoride content ranging from 0.3 to 1.2 ppm, the higher concentrations being associated with the dry seasons. The fluoride concentration in piped water from mountain rivers in Mourjes, Greece, ranged over the year between 1.3 to 2.0 ppm, the changes being apparently unrelated to rainfall. Marked variations in fluoride concentrations from 0.5 to over 3.5 ppm were observed in water from artesian wells in Assiros, Greece. In drinking waters from boreholes in Boennerup Strand, Denmark, fluoride concentrations ranged with time from 1.4 to 2.4 ppm, the variations being unrelated to climate or precipitation, while little variation in fluoride concentrations was found in water from boreholes in either Roedvig or Egens, Denmark. Water obtained from two sources of artificially fluoridated water supplies from Ireland showed considerable variations with time, although pooled samples indicated relatively constant levels over the year. The study indicates that the results of single fluoride ion measurement from any given source should not be taken as being a reliable indicator of fluoride exposure from drinking water.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Evaluation of an acid ammonium oxalate extraction to determine fluoride resident concentrations in soils.

    PubMed

    Bégin, Louis; Fortin, Josée

    2003-01-01

    Fluoride depositions near aluminum smelters and other fluoride-emitting plants can lead to fluoride accumulation in soils, which constitutes a risk for ground water contamination. This study was conducted to investigate the capacity of a 0.2 M acid ammonium oxalate solution to selectively and quantitatively extract fluoride accumulated in soils. The recovery of fluoride added to three soils was evaluated following 7- to 28-d incubations. Oxalate extraction was also compared with a total fluoride extraction method, using oxalate-extractable fluoride (Fox) and total fluoride (Ftot) accumulation profiles derived from column percolation experiments. To determine low-level fluoride concentrations without interference from high Al and Fe concentrations, an adapted ion chromatography method was used. Following soil incubations, oxalate extracted 42 to 86% of added fluoride. Recovery varied between soils and, in one soil, increased with added fluoride concentration. Recovery was unaffected by incubation time. Maximum recovery was obtained in a soil high in amorphous Fe and Al, low in clay, and free of carbonate. Lower recoveries were obtained in soils with higher clay or carbonate contents. Only 4 to 8% of Ftot was extracted in untreated samples using Fox, which suggests a high selectivity of this method for added fluoride. In percolation experiments, the use of Fox reduced considerably the background noise associated with Ftot for the evaluation of fluoride accumulation profiles. Because of its high selectivity and despite incomplete fluoride recovery, the use of Fox to determine fluoride resident concentrations in soils may improve environmental monitoring of fluoride accumulation and movement in contaminated soils.

  2. Comparative exploration of hydrogen sulfide and water transmembrane free energy surfaces via orthogonal space tempering free energy sampling

    DOE PAGES

    Lv, Chao; Aitchison, Erick W.; Wu, Dongsheng; Zheng, Lianqing; Cheng, Xiaolin; Yang, Wei

    2015-06-29

    Hydrogen sulfide (H2S), a commonly known toxic gas compound, possesses unique chemical features that allow this small solute molecule to quickly diffuse through cell membranes. Taking advantage of the recent orthogonal space tempering (OST) method, we comparatively mapped the transmembrane free energy landscapes of H2S and its structural analogue, water (H2O), seeking to decipher the molecular determinants that govern their drastically different permeabilities. Here, as revealed by our OST sampling results, in contrast to the highly polar water solute, hydrogen sulfide is evidently amphipathic, and thus inside membrane is favorably localized at the interfacial region, that is, the interface betweenmore » the polar head-group and nonpolar acyl chain regions. Because the membrane binding affinity of H2S is mainly governed by its small hydrophobic moiety and the barrier height inbetween the interfacial region and the membrane center is largely determined by its moderate polarity, the transmembrane free energy barriers to encounter by this toxic molecule are very small. Moreover when H2S diffuses from the bulk solution to the membrane center, the above two effects nearly cancel each other, so as to lead to a negligible free energy difference. Lastly, this study not only explains why H2S can quickly pass through cell membranes but also provides a practical illustration on how to use the OST free energy sampling method to conveniently analyze complex molecular processes.« less

  3. Comparative exploration of hydrogen sulfide and water transmembrane free energy surfaces via orthogonal space tempering free energy sampling.

    PubMed

    Lv, Chao; Aitchison, Erick W; Wu, Dongsheng; Zheng, Lianqing; Cheng, Xiaolin; Yang, Wei

    2016-03-01

    Hydrogen sulfide (H2 S), a commonly known toxic gas compound, possesses unique chemical features that allow this small solute molecule to quickly diffuse through cell membranes. Taking advantage of the recent orthogonal space tempering (OST) method, we comparatively mapped the transmembrane free energy landscapes of H2 S and its structural analogue, water (H2 O), seeking to decipher the molecular determinants that govern their drastically different permeabilities. As revealed by our OST sampling results, in contrast to the highly polar water solute, hydrogen sulfide is evidently amphipathic, and thus inside membrane is favorably localized at the interfacial region, that is, the interface between the polar head-group and nonpolar acyl chain regions. Because the membrane binding affinity of H2 S is mainly governed by its small hydrophobic moiety and the barrier height inbetween the interfacial region and the membrane center is largely determined by its moderate polarity, the transmembrane free energy barriers to encounter by this toxic molecule are very small. Moreover when H2 S diffuses from the bulk solution to the membrane center, the above two effects nearly cancel each other, so as to lead to a negligible free energy difference. This study not only explains why H2 S can quickly pass through cell membranes but also provides a practical illustration on how to use the OST free energy sampling method to conveniently analyze complex molecular processes. © 2015 Wiley Periodicals, Inc.

  4. Comparative exploration of hydrogen sulfide and water transmembrane free energy surfaces via orthogonal space tempering free energy sampling

    SciTech Connect

    Lv, Chao; Aitchison, Erick W.; Wu, Dongsheng; Zheng, Lianqing; Cheng, Xiaolin; Yang, Wei

    2015-06-29

    Hydrogen sulfide (H2S), a commonly known toxic gas compound, possesses unique chemical features that allow this small solute molecule to quickly diffuse through cell membranes. Taking advantage of the recent orthogonal space tempering (OST) method, we comparatively mapped the transmembrane free energy landscapes of H2S and its structural analogue, water (H2O), seeking to decipher the molecular determinants that govern their drastically different permeabilities. Here, as revealed by our OST sampling results, in contrast to the highly polar water solute, hydrogen sulfide is evidently amphipathic, and thus inside membrane is favorably localized at the interfacial region, that is, the interface between the polar head-group and nonpolar acyl chain regions. Because the membrane binding affinity of H2S is mainly governed by its small hydrophobic moiety and the barrier height inbetween the interfacial region and the membrane center is largely determined by its moderate polarity, the transmembrane free energy barriers to encounter by this toxic molecule are very small. Moreover when H2S diffuses from the bulk solution to the membrane center, the above two effects nearly cancel each other, so as to lead to a negligible free energy difference. Lastly, this study not only explains why H2S can quickly pass through cell membranes but also provides a practical illustration on how to use the OST free energy sampling method to conveniently analyze complex molecular processes.

  5. Analysis of laser shock experiments on precompressed samples using a quartz reference and application to warm dense hydrogen and helium

    NASA Astrophysics Data System (ADS)

    Brygoo, Stephanie; Millot, Marius; Loubeyre, Paul; Lazicki, Amy E.; Hamel, Sebastien; Qi, Tingting; Celliers, Peter M.; Coppari, Federica; Eggert, Jon H.; Fratanduono, Dayne E.; Hicks, Damien G.; Rygg, J. Ryan; Smith, Raymond F.; Swift, Damian C.; Collins, Gilbert W.; Jeanloz, Raymond

    2015-11-01

    Megabar (1 Mbar = 100 GPa) laser shocks on precompressed samples allow reaching unprecedented high densities and moderately high ˜103-104 K temperatures. We describe here a complete analysis framework for the velocimetry (VISAR) and pyrometry (SOP) data produced in these experiments. Since the precompression increases the initial density of both the sample of interest and the quartz reference for pressure-density, reflectivity, and temperature measurements, we describe analytical corrections based on available experimental data on warm dense silica and density-functional-theory based molecular dynamics computer simulations. Using our improved analysis framework, we report a re-analysis of previously published data on warm dense hydrogen and helium, compare the newly inferred pressure, density, and temperature data with most advanced equation of state models and provide updated reflectivity values.

  6. Potential Energy Curves of Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

    Fallon, Robert J.; Vanderslice, Joseph T.; Mason, Edward A.

    1960-01-01

    Potential energy curves for the X(sup 1)sigma+ and V(sup 1)sigma+ states of HF and DF have been calculated by the Rydberg-Klein-Rees method. The results calculated from the different sets of data for HF and DF are found to be in very good agreement. The theoretical results of Karo are compared to the experimental results obtained here.

  7. Direct measurements of stratospheric fluoride

    NASA Technical Reports Server (NTRS)

    Mroz, E. J.; Lazrus, A. L.; Bonelli, J. E.

    1977-01-01

    Stratospheric fluoride mass mixing ratios were measured by passing stratospheric air through filters half of which is impregnated in a base. Measurements of stratospheric fluoride were obtained at altitudes from 15 to 40 km at latitude 30-33 N and longitude 95-105 W at different months of the year. The significant amount of fluoride collected on the base-impregnated portion of the filters suggests that fluoride is present in the stratosphere as an acid gas. The mixing ratios decrease markedly at altitudes less than 20-25 km, suggesting the troposphere as the major sink for stratospheric fluoride.

  8. [Fluoride content of soft drinks produced in Poland].

    PubMed

    Jedra, Małgorzata; Urbanek-Karłowska, Bogumiła; Gawarska, Halina; Sawilska-Rautenstrauch, Dorota

    2006-01-01

    Fluoride content of 81 commercial brands of soft drinks and bottled waters were determined using potentiometric method with ion selective electrode. In the beverages produced in the same factory fluoride level were similar. The connection between elevation of fluoride levels and ingredients of investigated products such as juice or cola extract was not found. However, in some samples of ice tea drinks containing the tea extract fluoride levels might have been raised up to 1.28 mg/l. Fluoride contents of beverages from 28 producers ranged from 0.01 to 0.30 mg/l and only from 4 producers up to 0.60 mg/l. The highest level of fluoride (1.39 mg/l) has been determined in one sample of mineral water. In conclusion, ice tea beverages and certain mineral water, made and sold in Poland, may constitute an important source of fluoride in diet. Their consumption, particularly in case of children, must be controlled.

  9. Fluoride in water consumed by children in remote areas of Thailand.

    PubMed

    Chuckpaiwong, S; Nakornchai, S; Surarit, R; Soo-ampon, S; Kasetsuwan, R

    2000-06-01

    The objective of this study was to analyze fluoride content in water for drinking and for use in remote areas of Thailand. Water was sampled from schools and villages along the border by Multiple Stratified Cluster Random Sampling. Fluoride levels of 214 water samples from 48 schools and 48 villages were assessed in triplicate by fluoride ion electrode. The fluoride content in different regions and types of water were statistically analyzed by Kruskal-Wallis test at a significance level of 0.05. Results showed that fluoride in drinking water and water for use from the schools and villages were 0.01-0.37 ppm, 0.01-0.19 ppm, 0.01-0.87 ppm and 0.01-0.92 ppm, respectively. There was no difference in fluoride content in drinking water from various regions (p=0.23). However, there was a statistical difference in fluoride level in water for use (p=0.04, p=0.01) in various regions. The highest fluoride content was found in samples from the central and eastern region (0.19+/-0.24 ppm and 0.29+/-0.28 ppm respectively). When comparing types of water, ie ground water, surface water and rain water, there were differences in fluoride content (p=0.0). Underground water had the highest fluoride content (0.31+/-0.23 ppm).

  10. Fluorine (soluble fluoride)

    Integrated Risk Information System (IRIS)

    Fluorine ( soluble fluoride ) ; CASRN 7782 - 41 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for No

  11. Other Fluoride Products

    MedlinePlus

    ... in preventing tooth decay in people of all ages. Use the information listed below to compare the other fluoride products ... even among children younger than 6 years of age. Proper application technique ... cleared for marketing by the Food and Drug Administration (FDA) as ...

  12. Ferrimyoglobin-Fluoride.

    ERIC Educational Resources Information Center

    Russo, Steven O.; Hanania, George I. H.

    1990-01-01

    Described is an experiment which is designed to investigate the reaction of the protein ferrimyoglobin with fluoride. The activity uses readily available apparatus and the technique of optical absorbance for measurement of concentrations. Experimental design, procedures, and treatment of the equilibrium data are detailed. (CW)

  13. Response of grapevines to fluoride under field conditions

    SciTech Connect

    Murray, F.

    1983-07-01

    Grapevines (Vitis vinifera L. cv. Shiraz) were fumigated in open-top chambers with hydrogen fluoride for 64 days at mean atmospheric fluoride concentrations of 0.17 or 0.28 ..mu..gHFm/sup -3/. Other grapevines grown under ambient conditions in the vineyard or maintained in control chambers were exposed to 0.13 or 0.05 ..mu..gHFm/sup -3/, respectively. Leaves of grapevines exposed to 0.28, 0.17, 0.13, or 0.05 ..mu..gHFm/sup -3/ accumulated up to 85, 55, 20, or 11 ..mu..gFg/sup -1/, respectively. Foliar necrosis was observed on plants exposed to 0.28 ..mu..gHFm/sup -3/, but no injury symptoms were observed at 0.17 ..mu..gHFm/sup -3/ or in control plants. Grapevines growing under ambient conditions had significantly greater mean bunch weight, peduncle weight, number of grapes per bunch, and leaf protein levels than the fumigated treatments. However, these differences may be associated with a chamber effect rather than with an effect of fluoride on grapevines. No significant differences were found between treatments for grape potential alcohol content, fruit acids, number of bunches or grapes per vine, fresh weight of grapes, or leaf chlorophyll content, despite foliar fluoride concentrations in the highest fluoride fumigation level reaching 85 ..mu..gFg/sup -1/. No evidence was found of significant fluoride accumulation in berries or canes. 26 references, 4 tables.

  14. Method for decontamination of nickel-fluoride-coated nickel containing actinide-metal fluorides

    DOEpatents

    Windt, N.F.; Williams, J.L.

    In one aspect, the invention comprises contacting nickel-fluoride-coated nickel with gaseous ammonia at a temperature effecting nickel-catalyzed dissociation thereof and effecting hydrogen-reduction of the nickel fluoride. The resulting nickel is heated to form a melt and a slag and to effect transfer of actinide metals from the melt into the slag. The melt and slag are then separated. In another aspect, nickel contianing nickel oxide and actinide metals is contacted with ammonia at a temperature effecting nickel-catalyzed dissociation to effect conversion of the nickel oxide to the metal. The resulting nickel is then melted and separated as described. In another aspect nickel-fluoride-coated nickel containing actinide-metal fluorides is contacted with both steam and ammonia. The resulting nickel then is melted and separated as described. The invention is characterized by higher nickel recovery, efficient use of ammonia, a substantial decrease in slag formation and fuming, and a valuable increase in the service life of the furnace liners used for melting.

  15. Gas and hydrogen isotopic analyses of volcanic eruption clouds in Guatemala sampled by aircraft

    USGS Publications Warehouse

    Rose, W.I.; Cadle, R.D.; Heidt, L.E.; Friedman, I.; Lazrus, A.L.; Huebert, B.J.

    1980-01-01

    Gas samples were collected by aircraft entering volcanic eruption clouds of three Guatemalan volcanoes. Gas chromatographic analyses show higher H2 and S gas contents in ash eruption clouds and lower H2 and S gases in vaporous gas plumes. H isotopic data demonstrate lighter isotopic distribution of water vapor in ash eruption clouds than in vaporous gas plumes. Most of the H2O in the vaporous plumes is probably meteoric. The data are the first direct gas analyses of explosive eruptive clouds, and demonstrate that, in spite of atmospheric admixture, useful compositional information on eruptive gases can be obtained using aircraft. ?? 1980.

  16. Temperature measurements and hydrogen transformation under dynamic compression up to 150 GPA.

    NASA Astrophysics Data System (ADS)

    Nikolaev, Dmitry; Pyalling, Alexey; Kvitov, Sergey; Fortov, Vladimir

    2012-03-01

    Lithium fluoride single crystal window was used for optical light emission registration during quasi-isentropic compression of hydrogen to the pressures 100-150 GPa. Initially gaseous hydrogen samples at 78 K temperature and different pressures in the range 3-30 MPa were investigated. Recorded brightness temperature profiles in near infrared range of wavelength were analyzed to evaluate optical and transport properties of the investigated hydrogen sample and window. Two EOS models of hydrogen, with and without metallic region were used for 1-D simulation of it's properties under dynamic compression and estimation of hydrogen temperature within compressed layer. The obtained data demonstrate abrupt change of final temperatures after heating higher then 3500K.

  17. Sensitivity of two biomarkers for biomonitoring exposure to fluoride in children and women: A study in a volcanic area.

    PubMed

    Linhares, Diana Paula Silva; Garcia, Patrícia Ventura; Amaral, Leslie; Ferreira, Teresa; Cury, Jaime A; Vieira, Waldomiro; Rodrigues, Armindo Dos Santos

    2016-07-01

    The natural enrichment of water with fluoride is related to natural sources such as volcanic activity, with it being documented that fluorosis, an endemic and widespread disease in volcanic areas, is associated to the ingestion of high levels of fluoride through water. Thus, in this study, we aimed to define the fluoride concentration in drinking waters of volcanic origin and compare the sensitivity of urine and nail clippings as biomarkers for fluoride exposure in adults and children. Samples of drinking water from four villages in São Miguel Island (Azores) were used and the fluoride concentration was determined, as well the fluoride content in urine and toenails clippings from 66 children and 63 adults from these villages. A validated diet questionnaire, assessing sources of fluoride, was recorded for each participant. The fluoride determination in urine and nail clipping samples was made using a fluoride-specific electrode. A positive correlation was found between the fluoride daily intake and fluoride content in children urine (rs = 0.475; p < 0.001) and in their nail clippings (rs = 0.475; p < 0.001), while in adult women, the fluoride daily intake correlated positively with fluoride content nail clippings (rs = 0.495, p < 0.001). This reveals that nail clippings are more reliable as biomarkers of chronic exposure to fluoride than urine for populations of different ages (children vs. adults). Furthermore, nail clippings are more suitable than urine fluoride levels to assess long term exposure to fluoride in areas where the exposure to fluoride in drinking water is considered within, or slightly above, the recommended legal values.

  18. Sensitivity of two biomarkers for biomonitoring exposure to fluoride in children and women: A study in a volcanic area.

    PubMed

    Linhares, Diana Paula Silva; Garcia, Patrícia Ventura; Amaral, Leslie; Ferreira, Teresa; Cury, Jaime A; Vieira, Waldomiro; Rodrigues, Armindo Dos Santos

    2016-07-01

    The natural enrichment of water with fluoride is related to natural sources such as volcanic activity, with it being documented that fluorosis, an endemic and widespread disease in volcanic areas, is associated to the ingestion of high levels of fluoride through water. Thus, in this study, we aimed to define the fluoride concentration in drinking waters of volcanic origin and compare the sensitivity of urine and nail clippings as biomarkers for fluoride exposure in adults and children. Samples of drinking water from four villages in São Miguel Island (Azores) were used and the fluoride concentration was determined, as well the fluoride content in urine and toenails clippings from 66 children and 63 adults from these villages. A validated diet questionnaire, assessing sources of fluoride, was recorded for each participant. The fluoride determination in urine and nail clipping samples was made using a fluoride-specific electrode. A positive correlation was found between the fluoride daily intake and fluoride content in children urine (rs = 0.475; p < 0.001) and in their nail clippings (rs = 0.475; p < 0.001), while in adult women, the fluoride daily intake correlated positively with fluoride content nail clippings (rs = 0.495, p < 0.001). This reveals that nail clippings are more reliable as biomarkers of chronic exposure to fluoride than urine for populations of different ages (children vs. adults). Furthermore, nail clippings are more suitable than urine fluoride levels to assess long term exposure to fluoride in areas where the exposure to fluoride in drinking water is considered within, or slightly above, the recommended legal values. PMID:27155929

  19. Sampling and determination of gas-phase hydrogen peroxide following removal of ozone by gas-phase reaction with nitric oxide

    SciTech Connect

    Tanner, R.L.; Markovits, G.Y.; Ferreri, E.M.; Kelly, T.J.

    1986-01-01

    A method for determination of hydrogen peroxide in the ambient atmosphere is described, using impinger or diffusion scrubber collection of hydrogen peroxide with aqueous-phase analysis by an enzyme-catalyzed fluorescence technique. Interference from ozone at ambient levels is removed by gas-phase titration with excess nitric oxide. The impinger and diffusion scrubber collection techniques are shown to give equivalent results for atmospheric gas-phase hydrogen peroxide with limits of detection of 0.1 ppbv for approximately 60-min and 10-min sampling times, respectively.

  20. Histopathological changes of renal tissue following sodium fluoride administration in two consecutive generations of mice. Correlation with the urinary elimination of fluoride.

    PubMed

    Dimcevici Poesina, Nicoleta; Bălălău, Cristian; Nimigean, Vanda Roxana; Nimigean, Victor; Ion, Ion; Baconi, Daniela; Bârcă, Maria; Băran Poesina, Violeta

    2014-01-01

    The present study was designed to investigate the toxic effects (evaluated as histopathological changes) of sodium fluoride on the kidney in two consecutive generations of NMRI mice. An attempt to correlate the toxicity with the urinary elimination of fluoride has been made, as urinary fluoride excretion has been widely used as an indicator of fluoride intake and exposure. Six mixed (males and females) animal groups have been constituted by dividing the populations of mice derived from pregnant females (named "mothers" 0.5 mg sodium fluoride) treated with 0.5 mg sodium fluoride by daily gavage and pregnant females (named "mothers" 0.25 mg sodium fluoride) treated with 0.25 mg sodium fluoride by daily gavage; three types of sodium fluoride treatments were administrated: homeopathic, allopathic-homeopathic and allopathic. When the animals reached the adulthood, by randomization, they were selected in pairs for giving birth to the second generation of mice. No treatments were administrated to the second generation of mice; thus, the urinary elimination of fluoride in the second generation is attributed to exposure at sodium fluoride before birth. The administration of sodium fluoride to the first generation (F1) is realized until the mice reached the adulthood. For the first generation, the urine was collected at three times, every three weeks: at the age of four weeks, seven weeks and 11 weeks; single sampling urine, at the age of four weeks, has been conducted for the second generation. The urine samples have been analyzed using the ion selective electrode method for fluoride. For the histopathological examination, the animals were killed by cervical dislocation; the kidneys were collected in a 10% formalin solution. The preparation of samples for optical microscopy was realized with Hematoxylin-Eosin staining. The results indicate that the elimination of fluoride was similar (at the second evaluation, at 7-week-old of the first generation) for the both generations

  1. Sampling procedure for the measurement of dissolved hydrogen and volatile fatty acids in the rumen of dairy cows.

    PubMed

    Wang, M; Wang, R; Janssen, P H; Zhang, X M; Sun, X Z; Pacheco, D; Tan, Z L

    2016-03-01

    Dissolved hydrogen (dH) influences the pathways of VFA production and is a precursor of methane formation in the rumen. Measurements of dH in rumen fluid taken at the same time as measuring other rumen fermentation end products would improve our quantitative understanding of the role of dH as a controller of rumen fermentation. Sample collections though a rumen cannula and using oral stomach tubing were compared for measurements of dissolved gases and fermentation end products in the rumen fluid of 4 ruminally cannulated dairy cows fed a total mixed ration of corn silage and concentrate. Rumen fluid was collected at 0, 2.5, and 6 h after morning feeding through the cannula from cranial dorsal rumen, cranial ventral rumen, central rumen, caudal dorsal rumen, and caudal ventral rumen and in parallel by oral stomach tubing at 2 insertion depths of 180 cm (sampling the central rumen) and 200 cm (sampling the caudal dorsal rumen). The cranial dorsal rumen had the greatest pH and smallest VFA concentration among 5 sites sampled. Samples collected by oral stomach tubing had greater ( < 0.001) rumen pH and less ( < 0.001) dissolved methane (dCH) and lower VFA concentration than that collected through rumen cannula. The dH concentrations were positively correlated ( > 0.8) in rumen samples collected by the 2 sampling techniques, with a concordance correlation coefficient larger than 0.8 and scale shift being about 0.1 away from unity. The variations in the measurement of dH, dCH, pH, and VFA in samples collected by oral stomach tubing are most likely the result of saliva contamination. The time of sampling relative to feeding had significant influence ( < 0.01) on dissolved gases and fermentation end products, with the greatest concentrations of dH, dCH, and VFA measured 2.5 h after morning feeding. The dH was correlated positively ( > 0.58) with dCH and negatively ( < -0.65) with the estimated net H production relative to the amount of VFA produced. This indicated that

  2. Sampling procedure for the measurement of dissolved hydrogen and volatile fatty acids in the rumen of dairy cows.

    PubMed

    Wang, M; Wang, R; Janssen, P H; Zhang, X M; Sun, X Z; Pacheco, D; Tan, Z L

    2016-03-01

    Dissolved hydrogen (dH) influences the pathways of VFA production and is a precursor of methane formation in the rumen. Measurements of dH in rumen fluid taken at the same time as measuring other rumen fermentation end products would improve our quantitative understanding of the role of dH as a controller of rumen fermentation. Sample collections though a rumen cannula and using oral stomach tubing were compared for measurements of dissolved gases and fermentation end products in the rumen fluid of 4 ruminally cannulated dairy cows fed a total mixed ration of corn silage and concentrate. Rumen fluid was collected at 0, 2.5, and 6 h after morning feeding through the cannula from cranial dorsal rumen, cranial ventral rumen, central rumen, caudal dorsal rumen, and caudal ventral rumen and in parallel by oral stomach tubing at 2 insertion depths of 180 cm (sampling the central rumen) and 200 cm (sampling the caudal dorsal rumen). The cranial dorsal rumen had the greatest pH and smallest VFA concentration among 5 sites sampled. Samples collected by oral stomach tubing had greater ( < 0.001) rumen pH and less ( < 0.001) dissolved methane (dCH) and lower VFA concentration than that collected through rumen cannula. The dH concentrations were positively correlated ( > 0.8) in rumen samples collected by the 2 sampling techniques, with a concordance correlation coefficient larger than 0.8 and scale shift being about 0.1 away from unity. The variations in the measurement of dH, dCH, pH, and VFA in samples collected by oral stomach tubing are most likely the result of saliva contamination. The time of sampling relative to feeding had significant influence ( < 0.01) on dissolved gases and fermentation end products, with the greatest concentrations of dH, dCH, and VFA measured 2.5 h after morning feeding. The dH was correlated positively ( > 0.58) with dCH and negatively ( < -0.65) with the estimated net H production relative to the amount of VFA produced. This indicated that

  3. Health Effects Associated with Water Fluoridation.

    ERIC Educational Resources Information Center

    Richmond, Virginia L.

    1979-01-01

    Discussion is presented concerning fluoridation of water supplies. Correlation between fluoride in drinking water and improved dental health is reviewed. Relationship is expressed between fluoridation and reduced tooth decay. Use of fluoride in treating skeletal disorders is discussed. Author advocates fluoridating water supplies. (SA)

  4. Low-fluoride dentifrice and gastrointestinal fluoride absorption after meals.

    PubMed

    Cury, J A; Del Fiol, F S; Tenuta, L M A; Rosalen, P L

    2005-12-01

    A low-fluoride (F) dentifrice has been recommended to reduce the risk of dental fluorosis, but its anti-caries efficacy is questionable compared with that of conventional dentrifices (1000-1100 microg F/g). The tested hypothesis was that conventional dentifrices might be safe if used soon after meals, since food interferes with F absorption. In a crossover, double-blind study, 11 volunteers ingested a dentifrice slurry containing 0 (placebo), 550 (low F), or 1100 microg F/g in 3 gastric content situations: on fasting, or 15 min after breakfast or lunch. F was analyzed in saliva and 24-hour urine samples. The conventional dentifrice ingested after lunch resulted in only 10% higher F absorption than the low-F ingested on fasting. Analysis of the data suggests that the risk of fluorosis could be reduced by the use of either a low-F dentifrice or a conventional dentifrice, if toothbrushing occurred soon after meals.

  5. Bleaching gels containing calcium and fluoride: effect on enamel erosion susceptibility.

    PubMed

    Borges, Alessandra B; Torres, Carlos R G; de Souza, Paulo A B; Caneppele, Taciana M F; Santos, Luciana F T F; Magalhães, Ana Carolina

    2012-01-01

    This in vitro study evaluated the effect of 35% hydrogen peroxide (HP) bleaching gel modified or not by the addition of calcium and fluoride on enamel susceptibility to erosion. Bovine enamel samples (3 mm in diameter) were divided into four groups (n = 15) according to the bleaching agent: control-without bleaching (C); 35% hydrogen peroxide (HP); 35% HP with the addition of 2% calcium gluconate (HP + Ca); 35% HP with the addition of 0.6% sodium fluoride (HP + F). The bleaching gels were applied on the enamel surface for 40 min, and the specimens were subjected to erosive challenge with Sprite Zero and remineralization with artificial saliva for 5 days. Enamel wear was assessed using profilometry. The data were analyzed by ANOVA/ Tukey's test (P < 0.05). There were significant differences among the groups (P = 0.009). The most enamel wear was seen for C (3.37 ± 0.80 μm), followed by HP (2.89 ± 0.98 μm) and HP + F (2.72 ± 0.64 μm). HP + Ca (2.31 ± 0.92 μm) was the only group able to significantly reduce enamel erosion compared to C. The application of HP bleaching agent did not increase the enamel susceptibility to erosion. However, the addition of calcium gluconate to the HP gel resulted in reduced susceptibility of the enamel to erosion. PMID:23193404

  6. Actinide measurements by AMS using fluoride matrices

    NASA Astrophysics Data System (ADS)

    Cornett, R. J.; Kazi, Z. H.; Zhao, X.-L.; Chartrand, M. G.; Charles, R. J.; Kieser, W. E.

    2015-10-01

    Actinides can be measured by alpha spectroscopy (AS), mass spectroscopy or accelerator mass spectrometry (AMS). We tested a simple method to separate Pu and Am isotopes from the sample matrix using a single extraction chromatography column. The actinides in the column eluent were then measured by AS or AMS using a fluoride target matrix. Pu and Am were coprecipitated with NdF3. The strongest AMS beams of Pu and Am were produced when there was a large excess of fluoride donor atoms in the target and the NdF3 precipitates were diluted about 6-8 fold with PbF2. The measured concentrations of 239,240Pu and 241Am agreed with the concentrations in standards of known activity and with two IAEA certified reference materials. Measurements of 239,240Pu and 241Am made at A.E. Lalonde AMS Laboratory agree, within their statistical uncertainty, with independent measurements made using the IsoTrace AMS system. This work demonstrated that fluoride targets can produce reliable beams of actinide anions and that the measurement of actinides using fluorides agree with published values in certified reference materials.

  7. A novel fluoride ion colorimetric chemosensor based on coumarin

    NASA Astrophysics Data System (ADS)

    Zhuang, Xiaoqing; Liu, Weimin; Wu, Jiasheng; Zhang, Hongyan; Wang, Pengfei

    2011-09-01

    A novel visible colorimetric sensor ( L1) with high selectivity for fluoride ion based on coumarin has been synthesized by a simple modification of our earlier report. The chemosensor L1 shows an obvious color change from yellow to blue upon addition of fluoride ion with a large red shift of 145 nm in acetonitrile, and without interference of other anions such as Cl -, Br -, I -, NO 3-, H 2PO 4-, HSO 4-, and AcO -. The investigation of 1H NMR spectrum titration indicates the proposed mechanism is that F - first establishes a hydrogen bonding interaction with L1, and then the formation of [F-H-F] - induces deprotonation.

  8. Biomarkers of fluoride in children exposed to different sources of systemic fluoride.

    PubMed

    Buzalaf, M A R; Rodrigues, M H C; Pessan, J P; Leite, A L; Arana, A; Villena, R S; Forte, F D S; Sampaio, F C

    2011-02-01

    There has been no comparison between fluoride concentrations in urine and nails of children exposed to different sources of systemic fluoride. The aim of this study was to compare the relationship between fluoride intake with urinary fluoride excretion and fluoride concentrations in fingernails and toenails of children receiving fluoride from artificially fluoridated water (0.6-0.8 mg F/L, n = 25), naturally fluoridated water (0.6-0.9 mg F/L, n = 21), fluoridated salt (180-200 mg F/Kg, n = 26), and fluoridated milk (0.25 mg F, n = 25). A control population was included (no systemic fluoride, n = 24). Fluoride intake from diet and dentifrice, urinary fluoride excretion, and fluoride concentrations in fingernails/toenails were evaluated. Fluoride was analyzed with an ion-selective electrode. Urinary fluoride excretion in the control community was significantly lower when compared with that in the fluoridated cities, except for the naturally fluoridated community. However, the same pattern was not as evident for nails. Both urinary fluoride output and fluoride concentrations in fingernails/toenails were significantly correlated to total fluoride intake. However, the correlation coefficients for fluoride intake and urinary fluoride output were lower (r = 0.28, p < 0.01) than those observed for fingernails/toenails (r = 0.36, p < 0.001), suggesting that nails might be slightly better indicators of fluoride intake at the individual level.

  9. Fluoride occurrence in publicly supplied drinking water in Estonia

    NASA Astrophysics Data System (ADS)

    Karro, Enn; Indermitte, Ene; Saava, Astrid; Haamer, Kadri; Marandi, Andres

    2006-06-01

    A study was undertaken to examine the content and spatial distribution of fluoride in drinking water. Water samples (735) from public water systems covering all Estonian territory were analysed using SPADNS method. In order to specify the natural source of fluoride, the chemistry data from five aquifer systems utilised for water supply were included into the study. Fluoride concentrations in tap water, to a great extent, ranged from 0.01 to 6.95 mg/l. Drinking water in southern Estonia, where terrigenous Middle-Devonian aquifer system is exploited, has a fluoride concentration lower than recommended level (0.5 mg/l), thus promoting susceptibility to dental caries. The western part of the country is supplied by water with excess fluoride content (1.5-6.9 mg/l). Groundwater abstracted for drinking purposes originates from Ordovician and Silurian carbonate rocks. The content of fluoride in Silurian-Ordovician aquifer system is associated with the groundwater abstraction depth and the main controlling factors of dissolved fluoride are the pH value and the chemical type of water.

  10. Comparative study of fluoride released and recharged from conventional pit and fissure sealants versus surface prereacted glass ionomer technology

    PubMed Central

    Salmerón-Valdés, Elias Nahum; Scougall-Vilchis, Rogelio J; Alanis-Tavira, Jorge; Morales-Luckie, Raúl Alberto

    2016-01-01

    Context: The fluoride release of sealants in vitro shows a marked decrease. Giomers are distinguishable from manufactured resin-based sealants and contain prereacted glass-ionomer particles (PRG). Aims: To compare the amounts of fluoride released from the main pit and fissure of a resin-based sealant with that from a Giomer and to assess the abilities of the sealant and the Giomer to recharge when exposed to regular use of fluoride rinse. Materials and Methods: The readings for the fluoride concentration were carried out for 60 days using a fluoride ion-specific electrode. After this period, the samples were recharged using a fluoride mouth rinse. The amount of fluoride released after this recharge was determined for 5 days. The data were analyzed using Student's t- and analysis of variance tests. Results: In general, all materials presented higher fluoride release in the first 24 h; G1 and G4 showed a higher fluoride release in this period. On the other hand, G3 and G1 presented the most constant fluoride release until the 8th day, wherein all the sealants considerably decreased in the amount of fluoride released. Conclusion: G1 and G3 released higher concentrations of fluoride, although no significant differences were found. Giomers recharged in the first 24 h after polymerization presented an improved and sustained fluoride release. PMID:26957792

  11. Magnesium fluoride recovery method

    DOEpatents

    Gay, Richard L.; McKenzie, Donald E.

    1989-01-01

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is contacted with an acid under certain prescribed conditions to produce a liquid product and a particulate solid product. The particulate solid product is separated from the liquid and treated at least two more times with acid 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 pCi/gm. In accordance with a particularly preferred embodiment of the invention a catalyst and an oxidizing agent are used during the acid treatment and preferably the acid is sulfuric acid having a strength of about 1.0 Normal.

  12. Containerless processing of fluoride glass

    NASA Technical Reports Server (NTRS)

    Doremus, Robert H.

    1990-01-01

    Ground-based experiments on glass formation, crystallization, surface tension, vaporization, and chemical durability of a zirconium-barium-lanthanum (ZBL) fluoride glass are summarized. In a container large, columnar grains grew out from the container-glass interface during cooling. The main crystalline phase was alpha BaZrF6. A ZBL glass sphere was levitated acoustically during Shuttle flight STS-11. The glass was melted and then cooled while being levitated (containerless). Crystallization in the recovered sample was very fine and mainly beta BaZr2F10, showing the influence of the container on the nucleation and microstructure of crystallization in the glass. Glass formation should be easier for a containerless glass than in a container.

  13. Determination of fluoride source in ground water using petrographic studies in Dashtestan area, south of Iran

    NASA Astrophysics Data System (ADS)

    Battaleb-Looie, Sedigheh; Moore, Farid, ,, Dr.

    2010-05-01

    The groundwater occurs in Dashtestan area, contains a high level of fluoride. Since groundwater is vastly used for drinking and irrigation purposes, the local residents are at high risk of fluoride toxicity, as already evidenced by the occurrence of dental Fluorosis in many residents. 35 surface and groundwater samples were collected in September, 2009. The results show that in 23 samples the fluoride concentration is above the permissible level (1.5ppm). Petrographic study of lithological units in the catchment area indicates that mica minerals are the most probable source of fluoride content in the study area.

  14. Groundwater fluoride and dental fluorosis in southwestern Nigeria.

    PubMed

    Gbadebo, A M

    2012-10-01

    This study was carried out to assess the fluoride levels of groundwater from open wells, consumed by the residents of three communities located in two distinct geological terrains of southwestern Nigeria. Fluoride concentration was determined using spectrophotometric technique, while analysis of other parameters like temperature, pH and total dissolve solids followed standard methods. Results of the analysis indicated that groundwater samples from Abeokuta Metropolis (i.e., basement complex terrain) had fluoride content in the range of 0.65 ± 0.21 and 1.20 ± 0.14. These values were found to be lower than the fluoride contents in the groundwater samples from Ewekoro peri-urban and Lagos metropolis where the values ranged between 1.10 ± 0.14-1.45 ± 0.07 and 0.15 ± 0.07-2.20 ± 1.41 mg/l, respectively. The fluoride contents in almost all locations were generally higher than the WHO recommended 0.6 mg/l. Analysis of Duncan multiple range test indicated that there is similarity in the level of significance of fluoride contents between different locations of same geological terrain at p ≤ 0.05. It was also observed that fluoride distribution of groundwater samples from the different geological terrain was more dependent on factors like pH and TDS than on temperature. The result of the analyzed social demographic characteristics of the residents indicated that the adults (between the age of 20 and >40 years) showed dental decay than the adolescent (<20 years). This signifies incidence of dental fluorosis by the high fluoride content in the drinking water of the populace. Further investigation on all sources of drinking water and other causes of tooth decay in the area is suggested.

  15. Aqueous geochemistry of fluoride enriched groundwater in arid part of Western India.

    PubMed

    Singh, Chander Kumar; Mukherjee, Saumitra

    2015-02-01

    Fluoride-enriched water has become a major public health issue in India. The present study tries to evaluate the geochemical mechanism of fluoride enrichment in groundwater of western India. Total 100 groundwater samples were collected for the study spreading across the entire study area. The results of the analyzed parameters formed the attribute database for geographical information system (GIS) analysis and final output maps. A preliminary field survey was conducted and fluoride testing was done using Hach make field kits. The fluoride concentration ranges from 0.08 to 6.6 mg/L (mean 2.4 mg/L), with 63 % of the samples containing fluoride concentrations that exceed the World Health Organization (WHO) drinking water guideline value of 1.5 mg/L and 85 % samples exceeding the Bureau of Indian Standards (BIS) guidelines of 1 mg/L. The study also reveals high concentration of nitrate that is found to be above WHO standrads. The dominant geochemical facies present in water are Na-Cl-HCO3 (26 samples), Na-Ca-Cl-HCO3 (20 samples), Na-Cl (14 samples), and Na-Ca-Mg-Cl-HCO3 (11 samples); however, sodium and bicarbonate being the major component in all the water types of 100 samples, which in fact has a tendency to increase fluoride concentration in water by dissolving fluoride from fluorite. The thermodynamic considerations between the activities of calcium, fluoride, and bicarbonate suggest that fluoride concentration is being governed by activity of calcium ion. X-ray diffraction analysis of sediments reveals calcite and fluorite are the main solubility-control minerals controlling the aqueous geochemistry of high fluoride groundwater. The results indicate that the fluoride concentration in groundwater is mainly governed by geochemical composition of rocks, such as metamorphic granites and sedimentary rocks, alkaline hydrogeological environment, climatic conditions, high temperature and lesser rainfall, and geochemical processes such as weathering, evaporation

  16. Aqueous geochemistry of fluoride enriched groundwater in arid part of Western India.

    PubMed

    Singh, Chander Kumar; Mukherjee, Saumitra

    2015-02-01

    Fluoride-enriched water has become a major public health issue in India. The present study tries to evaluate the geochemical mechanism of fluoride enrichment in groundwater of western India. Total 100 groundwater samples were collected for the study spreading across the entire study area. The results of the analyzed parameters formed the attribute database for geographical information system (GIS) analysis and final output maps. A preliminary field survey was conducted and fluoride testing was done using Hach make field kits. The fluoride concentration ranges from 0.08 to 6.6 mg/L (mean 2.4 mg/L), with 63 % of the samples containing fluoride concentrations that exceed the World Health Organization (WHO) drinking water guideline value of 1.5 mg/L and 85 % samples exceeding the Bureau of Indian Standards (BIS) guidelines of 1 mg/L. The study also reveals high concentration of nitrate that is found to be above WHO standrads. The dominant geochemical facies present in water are Na-Cl-HCO3 (26 samples), Na-Ca-Cl-HCO3 (20 samples), Na-Cl (14 samples), and Na-Ca-Mg-Cl-HCO3 (11 samples); however, sodium and bicarbonate being the major component in all the water types of 100 samples, which in fact has a tendency to increase fluoride concentration in water by dissolving fluoride from fluorite. The thermodynamic considerations between the activities of calcium, fluoride, and bicarbonate suggest that fluoride concentration is being governed by activity of calcium ion. X-ray diffraction analysis of sediments reveals calcite and fluorite are the main solubility-control minerals controlling the aqueous geochemistry of high fluoride groundwater. The results indicate that the fluoride concentration in groundwater is mainly governed by geochemical composition of rocks, such as metamorphic granites and sedimentary rocks, alkaline hydrogeological environment, climatic conditions, high temperature and lesser rainfall, and geochemical processes such as weathering, evaporation

  17. Estimation of fluoride intake from milk-based infant formulas and baby foods.

    PubMed

    Noh, Hie Jin; Sohn, Woosung; Kim, Baek Il; Kwon, Ho Keun; Choi, Choong Ho; Kim, Hae-Young

    2015-03-01

    The aim of this study was to examine the amount of fluoride ingested from infant formula and baby food in infants aged up to 6 months in South Korea. The fluoride content of 20 commercially available formulas and 8 baby food samples from 4 different brands was measured using a modified microdiffusion method and fluoride ion selective electrode. The amount of fluoride (F) ingested by infants was estimated assuming that the samples were reconstituted with water containing 0, 0.5, 0.8, and 1.0 ppm F. When the reconstituted formulas and baby foods contained 0.8 ppm F water, the infants were estimated to ingest fluoride in the range of 0.018 to 0.298 mg/kg/day. The findings of this study suggest that there is a need for clear guidelines for fluoride consumption by infants that should be followed by manufacturers and parents.

  18. On-line hydrogen-isotope measurements of organic samples using elemental chromium: an extension for high temperature elemental-analyzer techniques.

    PubMed

    Gehre, Matthias; Renpenning, Julian; Gilevska, Tetyana; Qi, Haiping; Coplen, Tyler B; Meijer, Harro A J; Brand, Willi A; Schimmelmann, Arndt

    2015-01-01

    The high temperature conversion (HTC) technique using an elemental analyzer with a glassy carbon tube and filling (temperature conversion/elemental analysis, TC/EA) is a widely used method for hydrogen isotopic analysis of water and many solid and liquid organic samples with analysis by isotope-ratio mass spectrometry (IRMS). However, the TC/EA IRMS method may produce inaccurate δ(2)H results, with values deviating by more than 20 mUr (milliurey = 0.001 = 1‰) from the true value for some materials. We show that a single-oven, chromium-filled elemental analyzer coupled to an IRMS substantially improves the measurement quality and reliability for hydrogen isotopic compositions of organic substances (Cr-EA method). Hot chromium maximizes the yield of molecular hydrogen in a helium carrier gas by irreversibly and quantitatively scavenging all reactive elements except hydrogen. In contrast, under TC/EA conditions, heteroelements like nitrogen or chlorine (and other halogens) can form hydrogen cyanide (HCN) or hydrogen chloride (HCl) and this can cause isotopic fractionation. The Cr-EA technique thus expands the analytical possibilities for on-line hydrogen-isotope measurements of organic samples significantly. This method yielded reproducibility values (1-sigma) for δ(2)H measurements on water and caffeine samples of better than 1.0 and 0.5 mUr, respectively. To overcome handling problems with water as the principal calibration anchor for hydrogen isotopic measurements, we have employed an effective and simple strategy using reference waters or other liquids sealed in silver-tube segments. These crimped silver tubes can be employed in both the Cr-EA and TC/EA techniques. They simplify considerably the normalization of hydrogen-isotope measurement data to the VSMOW-SLAP (Vienna Standard Mean Ocean Water-Standard Light Antarctic Precipitation) scale, and their use improves accuracy of the data by eliminating evaporative loss and associated isotopic fractionation while

  19. On-line hydrogen-isotope measurements of organic samples using elemental chromium: an extension for high temperature elemental-analyzer techniques.

    PubMed

    Gehre, Matthias; Renpenning, Julian; Gilevska, Tetyana; Qi, Haiping; Coplen, Tyler B; Meijer, Harro A J; Brand, Willi A; Schimmelmann, Arndt

    2015-01-01

    The high temperature conversion (HTC) technique using an elemental analyzer with a glassy carbon tube and filling (temperature conversion/elemental analysis, TC/EA) is a widely used method for hydrogen isotopic analysis of water and many solid and liquid organic samples with analysis by isotope-ratio mass spectrometry (IRMS). However, the TC/EA IRMS method may produce inaccurate δ(2)H results, with values deviating by more than 20 mUr (milliurey = 0.001 = 1‰) from the true value for some materials. We show that a single-oven, chromium-filled elemental analyzer coupled to an IRMS substantially improves the measurement quality and reliability for hydrogen isotopic compositions of organic substances (Cr-EA method). Hot chromium maximizes the yield of molecular hydrogen in a helium carrier gas by irreversibly and quantitatively scavenging all reactive elements except hydrogen. In contrast, under TC/EA conditions, heteroelements like nitrogen or chlorine (and other halogens) can form hydrogen cyanide (HCN) or hydrogen chloride (HCl) and this can cause isotopic fractionation. The Cr-EA technique thus expands the analytical possibilities for on-line hydrogen-isotope measurements of organic samples significantly. This method yielded reproducibility values (1-sigma) for δ(2)H measurements on water and caffeine samples of better than 1.0 and 0.5 mUr, respectively. To overcome handling problems with water as the principal calibration anchor for hydrogen isotopic measurements, we have employed an effective and simple strategy using reference waters or other liquids sealed in silver-tube segments. These crimped silver tubes can be employed in both the Cr-EA and TC/EA techniques. They simplify considerably the normalization of hydrogen-isotope measurement data to the VSMOW-SLAP (Vienna Standard Mean Ocean Water-Standard Light Antarctic Precipitation) scale, and their use improves accuracy of the data by eliminating evaporative loss and associated isotopic fractionation while

  20. Structural, mechanistic, and computational analysis of the effects of anomeric fluorines on anomeric fluoride departure in 5-fluoroxylosyl fluorides.

    PubMed

    Lee, Seung Seo; Greig, Ian R; Vocadlo, David J; McCarter, John D; Patrick, Brian O; Withers, Stephen G

    2011-10-12

    The effects of fluorine substitution at the C-5 center of pyranosyl fluorides on the reactivity at the C-1 anomeric center was probed by studying a series of 5-fluoroxylosyl fluoride derivatives. X-ray structures of their per-O-acetates detailed the effects on the ground-state structures. First-order rate constants for spontaneous hydrolysis, in conjunction with computational studies, revealed that changes in the stereochemistry of the 5-fluorine had minimal effects on the solvolysis rate constants and that the observed rate reductions were broadly similar to those caused by additional fluorine substitution at C-1 but significantly less than those due to substitution at C-2. Differences in the trapping behavior of 5- versus 2-fluoro-substituted glycosyl fluorides with α- and β-glycosidases arise more from differences in steric effects and hydrogen-bonding interactions than from intrinsic reactivity differences.

  1. Inhibition of erosive wear by fluoride varnish.

    PubMed

    Vieira, A; Jager, D H J; Ruben, J L; Huysmans, M C D N J M

    2007-01-01

    It has been suggested that fluoride products with a protective mechanical component are advantageous in the prevention of erosive wear. The aim of this study was to evaluate in situ the effect of fluoride varnish (FV) in the prevention of wear due to erosion and combined erosion and toothbrush abrasion. Eleven volunteers wore for 3 weeks, during working hours, appliances containing 2 control and 2 FV-treated human enamel samples. Erosion took place extraorally 3 times a day (5 min) in the soft drink Sprite. At the end of each experimental day one control and one FV sample (C-er+abr and FV-er+abr) were brushed (5 s) with fluoridated dentrifice. The remaining control and FV sample (C-er and FV-er) were left unbrushed. Enamel volume loss was quantified by optical profilometry at day 5, 10 and 15. A statistically significant progression in enamel loss was found for the C-er, C-er+abr and FV-er+abr groups (p < 0.001, p < 0.001 and p = 0.001, respectively) but not for the FV-er group (p = 0.053). The values of cumulative normalized volume loss (x10(8) mum) at day 15 were: C-er 5.53 +/- 2.14, C-er+abr 5.70 +/- 2.07, FV-er 0.79 +/- 0.67 and FV-er+abr 2.76 +/- 1.35. The FV-er and FV-er+abr groups showed significant lower volume loss than the C-er group (p < 0.001 and p = 0.005, respectively) and the C-er+abr group (p < 0.001 and p = 0.002, respectively). The results indicate that fluoride varnish is effective in the reduction of erosive wear. PMID:17167261

  2. Fluoride in groundwater, Varaha River Basin, Visakhapatnam District, Andhra Pradesh, India.

    PubMed

    Rao, N Subba

    2009-05-01

    Excess intake of fluoride through drinking water causes fluorosis on human beings in many States of the country (India), including Andhra Pradesh. Groundwater quality in the Varaha River Basin located in the Visakhapatnam District of Andhra Pradesh has been studied, with reference to fluoride content, for its possible sources for implementing appropriate management measures, according to the controlling mechanism of fluoride concentration in the groundwater. The area occupied by the river basin is underlain by the Precambrian Eastern Ghats, over which the Recent sediments occur. Results of the chemical data of the groundwater suggest that the considerable number of groundwater samples show fluoride content greater than that of the safe limit prescribed for drinking purpose. Statistical analysis shows that the fluoride has a good positive relation, with pH and bicarbonate. This indicates an alkaline environment, as a dominant controlling mechanism for leaching of fluoride from the source material. Other supplementary factors responsible for the occurrence of fluoride in the groundwater are evapotranspiration, long contact time of water with the aquifer material, and agricultural fertilizers. A lack of correlation between fluoride and chloride, and a high positive correlation between fluoride and bicarbonate indicate recharge of the aquifer by the river water. However, the higher concentration of fluoride observed in the groundwater in some locations indicates insufficient dilution by the river water. That means the natural dilution did not perform more effectively. Hence, the study emphasizes the need for surface water management structures, with people's participation, for getting more effective results.

  3. Fluoride in groundwater, Varaha River Basin, Visakhapatnam District, Andhra Pradesh, India.

    PubMed

    Rao, N Subba

    2009-05-01

    Excess intake of fluoride through drinking water causes fluorosis on human beings in many States of the country (India), including Andhra Pradesh. Groundwater quality in the Varaha River Basin located in the Visakhapatnam District of Andhra Pradesh has been studied, with reference to fluoride content, for its possible sources for implementing appropriate management measures, according to the controlling mechanism of fluoride concentration in the groundwater. The area occupied by the river basin is underlain by the Precambrian Eastern Ghats, over which the Recent sediments occur. Results of the chemical data of the groundwater suggest that the considerable number of groundwater samples show fluoride content greater than that of the safe limit prescribed for drinking purpose. Statistical analysis shows that the fluoride has a good positive relation, with pH and bicarbonate. This indicates an alkaline environment, as a dominant controlling mechanism for leaching of fluoride from the source material. Other supplementary factors responsible for the occurrence of fluoride in the groundwater are evapotranspiration, long contact time of water with the aquifer material, and agricultural fertilizers. A lack of correlation between fluoride and chloride, and a high positive correlation between fluoride and bicarbonate indicate recharge of the aquifer by the river water. However, the higher concentration of fluoride observed in the groundwater in some locations indicates insufficient dilution by the river water. That means the natural dilution did not perform more effectively. Hence, the study emphasizes the need for surface water management structures, with people's participation, for getting more effective results. PMID:18509735

  4. Sustainable approach for recycling waste lamb and chicken bones for fluoride removal from water followed by reusing fluoride-bearing waste in concrete.

    PubMed

    Ismail, Zainab Z; AbdelKareem, Hala N

    2015-11-01

    Sustainable management of waste materials is an attractive approach for modern societies. In this study, recycling of raw waste lamb and chicken bones for defluoridation of water has been estimated. The effects of several experimental parameters including contact time, pH, bone dose, fluoride initial concentration, bone grains size, agitation rate, and the effect of co-existing anions in actual samples of wastewater were studied for fluoride removal from aqueous solutions. Results indicated excellent fluoride removal efficiency up to 99.4% and 99.8% using lamb and chicken bones, respectively at fluoride initial concentration of 10 mg F/L and 120 min contact time. Maximum fluoride uptake was obtained at neutral pH range 6-7. Fluoride removal kinetic was well described by the pseudo-second order kinetic model. Both, Langmuir and Freundlich isotherm models could fit the experimental data well with correlation coefficient values >0.99 suggesting favorable conditions of the process. Furthermore, for complete sustainable management of waste bones, the resulted fluoride-bearing sludge was reused in concrete mixes to partially replace sand. Tests of the mechanical properties of fluoride sludge-modified concrete mixes indicated a potential environmentally friendly approach to dispose fluoride sludge in concrete and simultaneously enhance concrete properties.

  5. Sustainable approach for recycling waste lamb and chicken bones for fluoride removal from water followed by reusing fluoride-bearing waste in concrete.

    PubMed

    Ismail, Zainab Z; AbdelKareem, Hala N

    2015-11-01

    Sustainable management of waste materials is an attractive approach for modern societies. In this study, recycling of raw waste lamb and chicken bones for defluoridation of water has been estimated. The effects of several experimental parameters including contact time, pH, bone dose, fluoride initial concentration, bone grains size, agitation rate, and the effect of co-existing anions in actual samples of wastewater were studied for fluoride removal from aqueous solutions. Results indicated excellent fluoride removal efficiency up to 99.4% and 99.8% using lamb and chicken bones, respectively at fluoride initial concentration of 10 mg F/L and 120 min contact time. Maximum fluoride uptake was obtained at neutral pH range 6-7. Fluoride removal kinetic was well described by the pseudo-second order kinetic model. Both, Langmuir and Freundlich isotherm models could fit the experimental data well with correlation coefficient values >0.99 suggesting favorable conditions of the process. Furthermore, for complete sustainable management of waste bones, the resulted fluoride-bearing sludge was reused in concrete mixes to partially replace sand. Tests of the mechanical properties of fluoride sludge-modified concrete mixes indicated a potential environmentally friendly approach to dispose fluoride sludge in concrete and simultaneously enhance concrete properties. PMID:26162903

  6. Effect of Fluoride, Chlorhexidine and Fluoride-chlorhexidine Mouthwashes on Salivary Streptococcus mutans Count and the Prevalence of Oral Side Effects

    PubMed Central

    Sadat Sajadi, Fatemeh; Moradi, Mohammad; Pardakhty, Abbas; Yazdizadeh, Razieh; Madani, Faezeh

    2015-01-01

    Background and aims. Streptococcus mutans is the main pathogenic agent involved in dental caries, and may be eliminated using mouthwashes. The objective of this study was to compare the effects of fluoride, chlorhexidine, and fluoride-chlorhexidine mouthwashes on salivary S. mutans count after two weeks of use and determine the prevalence of their side effects on the oral mucosa. Materials and methods. In this clinical trial, 120 12-14 year-old students were selected and divided into three groups. Each group was given one of fluoride, chlorhexidine, or fluoride-chlorhexidine mouthwashes. They were asked to use it twice a day for two weeks. Salivary samples were collected at baseline and after two weeks. Data were analyzed by Wilcoxon and Kruskal-Wallis tests. Results. In all the study groups, there were statistically significant reductions in salivary S. mutans counts two weeks after using the mouthwashes (P < 0.05). In addition, fluoride-chlorhexidine mouthwash had a significant effect on the reduction of S. mutans count in comparison with fluoride alone. The prevalence of oral side effects in fluoride-chlorhexidine mouth-wash was more than 90%. Conclusion. Adding fluoride to chlorhexidine mouthwash can significantly decrease salivary S. mutans count after two weeks. Fluoride-chlorhexidine has the highest rate of oral side effects between the evaluated mouthwash compounds. PMID:25973155

  7. Bone fluoride concentrations of eastern grey kangaroos (Macropus giganteus) resident near an aluminium smelter in south-eastern Australia.

    PubMed

    Hufschmid, J; Beveridge, I; Coulson, G; Gould, J

    2011-08-01

    Lesions of skeletal and dental fluorosis have been described recently in eastern grey kangaroos (Macropus giganteus). The present study further examined the epidemiology of skeletal fluorosis in this species. Bone fluoride concentrations were obtained from a range of skeletal sites of animals from a high (Portland Aluminium) and a low (Cape Bridgewater) fluoride environment in Victoria, Australia. Age, but not sex, affected the mean bone fluoride concentration of kangaroos. For a given age, bone fluoride concentrations were significantly higher in kangaroos from Portland than Cape Bridgewater. Concentrations varied between skeletal sites examined, with samples containing cancellous bone having higher fluoride concentrations than those containing only cortical bone.

  8. Fluoride-treated bio-resorbable synthetic nonceramic [corrected] hydroxyapatite promotes proliferation and differentiation of human osteoblastic MG-63 cells.

    PubMed

    Ohno, Motofumi; Kimoto, Kazunari; Toyoda, Toshihisa; Kawata, Kazushige; Arakawa, Hirohisa

    2013-04-01

    When resorbable hydroxyapatite (HA) granules, which are used as a bone supplement material, were treated in neutral 4% sodium fluoride (NaF) solution, formation of a reactant resembling calcium fluoride was observed on the surface of the granules. Immediate and slow release of fluoride from fluoridated HA (HA+F) granules was observed after immersion in culture fluid, and the concentration increased over time to 1.25 ± 0.05 ppm F at 0.5 hours, 1.57 ± 0.12 ppm F at 24 hours, and 1.73 ± 0.15 ppm F at 48 hours. On invasion assay, migration of human osteoblast-like MG-63 cells exposed to the released fluoride was confirmed in comparison to the cells incubated with a nonfluoridated control sample (P < .01). In addition, fluoride added to the medium increased MG-63 cell proliferation in a manner dependent on fluoride concentrations up to 2.0 ppm (P < .05). At 5.0 ppm, however, fluoride significantly inhibited cell proliferation (P < .005). Activity of the osteogenic differentiation marker, alkaline phosphatase (ALP), also increased with fluoride after exposure for 1 week, increasing significantly at 1.0 ppm (P < .05). The promotion of MG-63 cell migration and proliferation, as well as increased ALP activity, suggested that fluoride released from the surface of resorbable HA granules, which were fluoridated by prior treatment with neutral 4% NaF solution, can provide a superb method to supply fluoride and promote osteogenic cell differentiation.

  9. Prompt gamma tests of LaBr3:Ce and BGO detectors for detection of hydrogen, carbon and oxygen in bulk samples

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Al-Matouq, Fares A.; Khiari, F. Z.; Isab, A. A.; Rehman, Khateeb-ur; Raashid, M.

    2012-08-01

    Prompt gamma ray tests of cylindrical lanthanum halide (LaBr3:Ce) and bismuth germanate (BGO) gamma ray detectors have been carried out for detection of hydrogen, carbon and oxygen concentrations in bulk samples via inelastic scattering of neutrons using a 14 MeV neutron-based prompt gamma neutron activation analysis setup. Regardless of its intrinsic activity, the LaBr3:Ce detector showed superior performance than the BGO detector for the detection of hydrogen, carbon and oxygen concentrations in benzene, water, toluene, propanol, ethanol and methanol bulk samples. The BGO detector has a large concentration of oxygen in its detector material and is consequently less sensitive for oxygen detection in bulk samples. Hence, it is not a suitable choice for oxygen determination in bulk samples.

  10. WET FLUORIDE SEPARATION METHOD

    DOEpatents

    Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

    1958-11-25

    The separation of U/sup 233/ from thorium, protactinium, and fission products present in neutron-irradiated thorium is accomplished by dissolving the irradiated materials in aqueous nitric acid, adding either a soluble fluoride, iodate, phosphate, or oxalate to precipltate the thorium, separating the precipltate from the solution, and then precipitating uranlum and protactinium by alkalizing the solution. The uranium and protactinium precipitate is removcd from the solution and dissolved in nitric acid. The uranyl nitrate may then be extracted from the acid solution by means of ether, and the protactinium recovered from the aqueous phase.

  11. Determination of fluoride in tap water in Morocco using a direct electrochemical method.

    PubMed

    El Jaoudi, Rachid; Mamouch, Fouzia; Ait El Cadi, Mina; Bousliman, Yassir; Cherrah, Yahia; Bouklouze, Abdelaziz

    2012-08-01

    This study aimed to analyze the fluoride concentration in tap drinking water in different cities of Morocco using an electrochemical ion-selective method. Three samples were collected from each thirteen selected cities in the period between March and May 2011. The median value of fluoride was 0.94 mg/L (0.21-2.97). High fluoride concentrations (>0.8 mg/L) were found in sixteen cities. Very high values were found in phosphate regions such as Khouribga which is known to be an endemic dental fluorosis area. This study has shown that the concentration of fluoride in drinking water exceeds the limit especially in phosphate regions.

  12. Fluoride in the drinking water of Nagaur tehsil of Nagaur District, Rajasthan, India.

    PubMed

    Arif, M; Hussain, I; Hussain, J; Sharma, S; Kumar, S

    2012-06-01

    Fluoride concentration of groundwater samples from 100 villages of Nagaur tehsil was determined, 85 villages were found to have fluoride concentration more than 1.5 mg/L. The maximum fluoride concentration was recorded 6.6 mg/L in groundwater of Singhani village, while the minimum was recorded in Kurchhi village. As per the desirable and maximum permissible limit for fluoride in drinking water, determined by World Health Organization, the groundwater of about 85 villages of the studied sites is unfit for drinking purpose. PMID:22415642

  13. Community Water Fluoridation and Intelligence: Prospective Study in New Zealand

    PubMed Central

    Thomson, W. Murray; Ramrakha, Sandhya; Moffitt, Terrie E.; Zeng, Jiaxu; Foster Page, Lyndie A.; Poulton, Richie

    2015-01-01

    Objectives. This study aimed to clarify the relationship between community water fluoridation (CWF) and IQ. Methods. We conducted a prospective study of a general population sample of those born in Dunedin, New Zealand, between April 1, 1972, and March 30, 1973 (95.4% retention of cohort after 38 years of prospective follow-up). Residence in a CWF area, use of fluoride dentifrice and intake of 0.5-milligram fluoride tablets were assessed in early life (prior to age 5 years); we assessed IQ repeatedly between ages 7 to 13 years and at age 38 years. Results. No clear differences in IQ because of fluoride exposure were noted. These findings held after adjusting for potential confounding variables, including sex, socioeconomic status, breastfeeding, and birth weight (as well as educational attainment for adult IQ outcomes). Conclusions. These findings do not support the assertion that fluoride in the context of CWF programs is neurotoxic. Associations between very high fluoride exposure and low IQ reported in previous studies may have been affected by confounding, particularly by urban or rural status. PMID:24832151

  14. Community Water Fluoridation and Intelligence: Prospective Study in New Zealand.

    PubMed

    Broadbent, Jonathan M; Thomson, W Murray; Ramrakha, Sandhya; Moffitt, Terrie E; Zeng, Jiaxu; Foster Page, Lyndie A; Poulton, Richie

    2015-01-01

    Objectives. This study aimed to clarify the relationship between community water fluoridation (CWF) and IQ. Methods. We conducted a prospective study of a general population sample of those born in Dunedin, New Zealand, between April 1, 1972, and March 30, 1973 (95.4% retention of cohort after 38 years of prospective follow-up). Residence in a CWF area, use of fluoride dentifrice and intake of 0.5-milligram fluoride tablets were assessed in early life (prior to age 5 years); we assessed IQ repeatedly between ages 7 to 13 years and at age 38 years. Results. No clear differences in IQ because of fluoride exposure were noted. These findings held after adjusting for potential confounding variables, including sex, socioeconomic status, breastfeeding, and birth weight (as well as educational attainment for adult IQ outcomes). Conclusions. These findings do not support the assertion that fluoride in the context of CWF programs is neurotoxic. Associations between very high fluoride exposure and low IQ reported in previous studies may have been affected by confounding, particularly by urban or rural status.

  15. Fluoride concentrations in a crystalline bedrock aquifer Marathon County, Wisconsin

    NASA Astrophysics Data System (ADS)

    Ozsvath, David L.

    2006-05-01

    Water samples from 2,789 private water-supply wells in Marathon County, Wisconsin reveal that fluoride concentrations in the crystalline bedrock range from <0.01 to 7.60 mg/L, with 0.6% of the values exceeding the Environmental Protection Agency’s (EPA’s) maximum contaminant level of 4 mg/L, and 8.6% exceeding the EPA’s secondary maximum contaminant level of 2.0 mg/L. Roughly a quarter of the wells contain dissolve fluoride within the range considered optimal for human health (between 0.5 and 1.5 mg/L), whereas 63.3% fall below 0.5 mg/L. Consistent with studies conducted in other regions, felsic rocks have significantly higher fluoride concentrations than mafic and metasedimentary rocks. Syenites yield the most fluoriferous groundwaters, but the highest median concentration occurs in a sodium-plagioclase granite. A relationship between plagioclase composition and fluoride concentrations suggests that dissolved fluoride levels are controlled by fluorite solubility and that higher fluoride concentrations are found in soft, sodium-rich groundwater.

  16. An investigation of suitable bag materials for the collection and storage of breath samples containing hydrogen cyanide.

    PubMed

    Gilchrist, Francis J; Razavi, Cyrus; Webb, A Kevin; Jones, Andrew M; Spaněl, Patrik; Smith, David; Lenney, Warren

    2012-09-01

    The SPACE study will assess exhaled breath hydrogen cyanide (HCN) concentrations as a marker of Pseudomonas aeruginosa (PA) infection in 240 children with cystic fibrosis (CF). It will use off-line selected ion flow tube mass spectrometry (SIFT-MS) analysis and so we needed to investigate which breath sampling bag material to use, the maximum storage time before analysis and the benefit of warming the bag samples. We studied 15 children with CF, 8 had chronic PA infection and 7 did not. Each exhaled directly into the instrument (on-line) and also into two 25 µm thick Nalophan (25N), two 70 µm Nalophan (70N) and two Tedlar® bags. Bags were stored at 20 or 37 °C. HCN concentrations were analysed at 1, 6, 24 and 48 h (off-line). Acetone and water vapour concentrations were also measured in parallel. Correlation between on-line and off-line concentrations measured by SIFT-MS was better for all compounds and bag types at 37 °C. The median (IQR) on-line HCN concentration was 8.9(4.4-13.7) parts per billion by volume, ppbv. Both on-line and off-line HCN concentrations were significantly higher in patients with PA infection than those without. At 37 °C the correlation between on-line and off-line HCN concentrations was good up to 6 h in the 25N bag (R(2) = 0.79) and up to 24 h for the 70N and Tedlar bags (R(2) = 0.82 and 0.86). The correlation between on- and off-line acetone concentrations at 37 °C was good up to 24 h in 25N, 70N and Tedlar bags (R(2) = 0.89, 0.93 and 0.97). In all three types of bag the water vapour concentration fell quickly and by 24 h was equivalent to that of lab air. Samples stored in Tedlar or 70N bags, warmed to 37 °C and analysed within 24 h, give HCN and acetone concentrations which correlate well with on-line measurements.

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

    ERIC Educational Resources Information Center

    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…

  18. Comparative evaluation and effect of organic and inorganic fluoride dentifrices on enamel microhardness: An in vitro study

    PubMed Central

    Shetty, Krishna Prasad; Satish, S. V.; Gouda, Veerbhadra; Badade, Abhishek Rajpal; Gouda, Basavana; Patil, Snehalata

    2016-01-01

    Aim: To compare and evaluate the microhardness of enamel surface after the application of organic fluoride and inorganic fluoride dentifrices. Materials and Methods: Twenty freshly extracted premolars were collected and decoronation of all the teeth was done at cementoenamel junction. The crowns were sectioned mesiodistally into two halves with the help of diamond disc, and then the subsequent forty samples kept in 1% citric acid for the demineralization and divided into two groups by simple randomization, that is, Group A (inorganic sodium fluoride dentifrice) and Group B (organic amine fluoride dentifrice). They were treated using same protocol for 3 min, daily twice for 7 days. Those samples preserved in artificial saliva in between treatment. The enamel surface microhardness evaluated using Vickers hardness test at base level, after demineralization, as well as after remineralization. Statistical analysis of surface microhardness obtained at different stages done by Student's t-test and P < 0.05 was considered statistically significant. Results: The samples which were treated with sodium fluoride (Group A) could not restore the mean microhardness after treatment to that of preoperative level whereas amine fluoride (Group B) treated samples showed a statistically significant increase in mean surface microhardness from baseline. Conclusion: Organic fluoride (amine fluoride) remineralization was more effective in restoring enamel microhardness than inorganic fluoride (sodium fluoride) remineralization. PMID:27114952

  19. Effects of simulated solar radiation on the transmission of magnesium fluoride and cryolite thin films

    NASA Technical Reports Server (NTRS)

    Heslin, T.

    1974-01-01

    Thin films of cryolite magnesium fluoride on fused silica substrates were exposed to 1126 equivalent sun-hours of radiation. The optical transmissions of the samples were measured before and after irradiation. The results indicate that, after the degradation of the silica substrate is accounted for, the cryolite is severely affected by the simulated solar radiation, but the magnesium fluoride is only slightly affected.

  20. Optical Restoration of Lead Fluoride Crystals

    SciTech Connect

    Spilker, A.; Cole, P. L.; Forest, T. A.; Mestari, M.; Naeem, S.; LeBaron, N.; Bertin, P.; Camacho, C. Munoz; Roche, J.

    2009-03-10

    Due to its relatively high resistance to high radiation, lead fluoride (PbF{sub 2}) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF{sub 2} crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF{sub 2} samples with 1.1 and 1.3 MeV gammas from {sup 60}Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410-450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF{sub 2} samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching.

  1. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-01-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  2. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Delcul, G. D.; Dai, S.; Metcalf, D. H.

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  3. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-09-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established.

  4. Molten fluoride fuel salt chemistry

    SciTech Connect

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1994-09-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established.

  5. Fluoride: A naturally-occurring health hazard in drinking-water resources of Northern Thailand.

    PubMed

    Chuah, C Joon; Lye, Han Rui; Ziegler, Alan D; Wood, Spencer H; Kongpun, Chatpat; Rajchagool, Sunsanee

    2016-03-01

    In Northern Thailand, incidences of fluorosis resulting from the consumption of high-fluoride drinking-water have been documented. In this study, we mapped the high-fluoride endemic areas and described the relevant transport processes of fluoride in enriched waters in the provinces of Chiang Mai and Lamphun. Over one thousand surface and sub-surface water samples including a total of 995 collected from shallow (depth: ≤ 30 m) and deep (> 30 m) wells were analysed from two unconnected high-fluoride endemic areas. At the Chiang Mai site, 31% of the shallow wells contained hazardous levels (≥ 1.5 mg/L) of fluoride, compared with the 18% observed in the deep wells. However, at the Lamphun site, more deep wells (35%) contained water with at least 1.5mg/L fluoride compared with the shallow wells (7%). At the Chiang Mai site, the high-fluoride waters originate from a nearby geothermal field. Fluoride-rich geothermal waters are distributed across the area following natural hydrological pathways of surface and sub-surface water flow. At the Lamphun site, a well-defined, curvilinear high-fluoride anomalous zone, resembling that of the nearby conspicuous Mae Tha Fault, was identified. This similarity provides evidence of the existence of an unmapped, blind fault as well as its likely association to a geogenic source (biotite-granite) of fluoride related to the faulted zone. Excessive abstraction of ground water resources may also have affected the distribution and concentration of fluoride at both sites. The distribution of these high-fluoride waters is influenced by a myriad of complex natural and anthropogenic processes which thus created a challenge for the management of water resources for safe consumption in affected areas. The notion of clean and safe drinking water can be found in deeper aquifers is not necessarily true. Groundwater at any depth should always be tested before the construction of wells. PMID:26747991

  6. Fluoride: A naturally-occurring health hazard in drinking-water resources of Northern Thailand.

    PubMed

    Chuah, C Joon; Lye, Han Rui; Ziegler, Alan D; Wood, Spencer H; Kongpun, Chatpat; Rajchagool, Sunsanee

    2016-03-01

    In Northern Thailand, incidences of fluorosis resulting from the consumption of high-fluoride drinking-water have been documented. In this study, we mapped the high-fluoride endemic areas and described the relevant transport processes of fluoride in enriched waters in the provinces of Chiang Mai and Lamphun. Over one thousand surface and sub-surface water samples including a total of 995 collected from shallow (depth: ≤ 30 m) and deep (> 30 m) wells were analysed from two unconnected high-fluoride endemic areas. At the Chiang Mai site, 31% of the shallow wells contained hazardous levels (≥ 1.5 mg/L) of fluoride, compared with the 18% observed in the deep wells. However, at the Lamphun site, more deep wells (35%) contained water with at least 1.5mg/L fluoride compared with the shallow wells (7%). At the Chiang Mai site, the high-fluoride waters originate from a nearby geothermal field. Fluoride-rich geothermal waters are distributed across the area following natural hydrological pathways of surface and sub-surface water flow. At the Lamphun site, a well-defined, curvilinear high-fluoride anomalous zone, resembling that of the nearby conspicuous Mae Tha Fault, was identified. This similarity provides evidence of the existence of an unmapped, blind fault as well as its likely association to a geogenic source (biotite-granite) of fluoride related to the faulted zone. Excessive abstraction of ground water resources may also have affected the distribution and concentration of fluoride at both sites. The distribution of these high-fluoride waters is influenced by a myriad of complex natural and anthropogenic processes which thus created a challenge for the management of water resources for safe consumption in affected areas. The notion of clean and safe drinking water can be found in deeper aquifers is not necessarily true. Groundwater at any depth should always be tested before the construction of wells.

  7. Health risk assessment of fluoride in drinking water from Anhui Province in China.

    PubMed

    Gao, Hong-jian; Jin, You-qian; Wei, Jun-ling

    2013-05-01

    This study analyzes the concentrations and health risks of fluoride in 249 drinking water samples collected from different regions of Anhui Province in China. Results indicated that fluoride content in drinking water ranged from 0.12 to 1.94 mg L(-1) (mean = 0.57 mg L(-1)) in the following order: Huaibei plain region > Jianghuai hill region ≈ Dabieshan mountainous region > plain along the Yangtze River region > southern Anhui mountainous region. The fluoride contents were less than 0.50 mg L(-1) in 66.66 % of the drinking water samples, 0.51-1.0 mg L(-1) in 23.29 %, and higher than 1.0 mg L(-1) in 12.04 %. The fluoride levels in some samples were lower than the recommended values for controlling dental caries (0.50-1.0 mg L(-1)). The total fluoride intake from drinking water was between 0.14 and 2.33 mg per day in different regions of the province, supposing an individual consumes 1.2 L of water per day. Therefore, measures should be taken to increase fluoride intake in the Jianghuai hill region, Dabieshan mountainous region, plain along the Yangtze River, and southern Anhui mountainous region to control dental caries. On the other hand, the fluoride levels must be reduced in the Huaibei plain region to decrease endemic fluorosis. The results serve as crucial guidelines for managing fluoride safety in drinking water and controlling endemic fluorosis in different regions of Anhui Province.

  8. Do Fluoride Ions Protect Teeth?

    ERIC Educational Resources Information Center

    Parkin, Christopher

    1998-01-01

    Begins with the procedure and results from an investigation on the effect of fluoride on the reaction between eggshell (substitute teeth) and dilute ethanoic acid. Describes an elegantly modified and improvised apparatus. (DDR)

  9. FLUORIDE CONCENTRATION IN WATER AT THE AREA SUPPLIED BY THE WATER TREATMENT STATION OF BAURU, SP

    PubMed Central

    Lodi, Carolina Simonetti; Ramires, Irene; Buzalaf, Marília Afonso Rabelo; Bastos, José Roberto de Magalhães

    2006-01-01

    Objective: to analyze the fluoride concentration in the public water supply at the area supplied by the Water Treatment Station of Bauru and classify the samples as acceptable or unacceptable according to the fluoride concentration. Material and methods: samples were collected from 30 areas at two periods, October 2002 and March 2003. The fluoride concentration in the samples was determined in duplicate, using an ion sensitive electrode (Orion 9609) connected to a potentiometer (Procyon, model 720). Samples with fluoride concentration ranging from 0.55 to 0.84 mg F/L were considered acceptable, and those whose concentration was outside this range as unacceptable. Data were analyzed by descriptive statistics. Results: the fluoride concentration of the water samples varied between 0.31 and 2.01 mg F/L. Nearly 56% of the samples were classified as acceptable. Conclusion: the variations in fluoride concentration at the area supplied by the Water Treatment Station reinforce the need of constant monitoring for maintenance of adequate fluoride levels in the public water supply. PMID:19089059

  10. Isolation, identification and characterization of fluoride resistant bacteria: possible role in bioremediation.

    PubMed

    Chouhan, S; Tuteja, U; Flora, S J S

    2012-01-01

    Microorganisms found in industrial effluents and near the sites of the contamination can be used to indicate pollution and detoxify the contaminated water resources. Emergence of xenobiotic resistant bacteria among them might be potential application in bioremediation. The objective of this study was to isolate and characterize fluoride resistant bacteria from soil and water samples of different regions of India. Five isolates were recovered from different samples which were found to be fluoride resistant. Two of them effectively reduced the fluoride from their media. Through the current study it can be predicted that fluoride pollution results in selective pressure that leads to the development of fluoride resistant among bacterial populations, probably through the mechanism which involved high affinity anion binding compounds called ionophores. Resistant microbes may play a bioremediative role by transforming and concentrating these anions so that they are less available and less dangerous. PMID:22567885

  11. Aminobenzohydrazide based colorimetric and 'turn-on' fluorescence chemosensor for selective recognition of fluoride.

    PubMed

    Anand, Thangaraj; Sivaraman, Gandhi; Iniya, Murugan; Siva, Ayyanar; Chellappa, Duraisamy

    2015-05-30

    Chemosensors based on aminobenzohydrazide Schiff bases bearing pyrene/anthracene as fluorophores have been designed and synthesized for F(-) ion recognition. The addition of fluoride ions to the receptors causes a dramatically observable colour change from pale yellow to brown/red. (1)H NMR studies confirm that the F(-) ion facilitates its recognition by forming hydrogen bond with hydrogens of amide and amine groups. Moreover these sensors have also been successfully applied to detection of fluoride ion in commercial tooth paste solution. PMID:25998453

  12. Determination of glucose using a coupled-enzymatic reaction with new fluoride selective optical sensing polymeric film coated in microtiter plate wells.

    PubMed

    Abd-Rabboh, Hisham S M; Meyerhoff, Mark E

    2007-05-15

    The determination of glucose in beverages is demonstrated using newly developed fluoride selective optical sensing polymeric film that contains aluminum (III) octaethylporphyrin (Al[OEP]) ionophore and the chromoionophore ETH7075 cast at the bottom of wells of a 96-well polypropylene microtiter plate. The method uses a dual enzymatic reaction involving glucose oxidase enzyme (GOD) and horseradish peroxidase (HRP), along with an organofluoro-substrate (4-fluorophenol) as the source of fluoride ions. The concentration of fluoride ions after enzymatic reaction is directly proportional to the glucose level in the sample. The method has a detection limit of 0.8 mmol L(-1), a linear range of 0.9- 40 mmol L(-1) and a sensitivity of 0.125 absorbance unit/decade of glucose concentration. Glucose levels in several beverage samples determined using the proposed method correlate well with a reference spectrophotometric enzyme method based on detection of hydrogen peroxide using bromopyrogallol red dye (BPR). The new method can also be used to determine H(2)O(2) concentrations in the 0.1 - 50 mmol L(-1) range using a single enzymatic reaction involving H(2)O(2) oxidation of 4-fluorophenol catalyzed by HRP. The methodology could potentially be used to detect a wide range of substrates for which selective oxidase enzymes exist (to generate H(2)O(2)), with the high throughput of simple microtiter plate detection scheme.

  13. Determination of glucose using a coupled-enzymatic reaction with new fluoride selective optical sensing polymeric film coated in microtiter plate wells

    PubMed Central

    Abd-Rabboh, Hisham S. M.; Meyerhoff, Mark E.

    2007-01-01

    The determination of glucose in beverages is demonstrated using newly developed fluoride selective optical sensing polymeric film that contains aluminum (III) octaethylporphyrin (Al[OEP]) ionophore and the chromoionophore ETH7075 cast at the bottom of wells of a 96-well polypropylene microtiter plate. The method uses a dual enzymatic reaction involving glucose oxidase enzyme (GOD) and horseradish peroxidase (HRP), along with an organofluoro-substrate (4-fluorophenol) as the source of fluoride ions. The concentration of fluoride ions after enzymatic reaction is directly proportional to the glucose level in the sample. The method has a detection limit of 0.8 mmol L−1, a linear range of 0.9– 40 mmol L−1 and a sensitivity of 0.125 absorbance unit/decade of glucose concentration. Glucose levels in several beverage samples determined using the proposed method correlate well with a reference spectrophotometric enzyme method based on detection of hydrogen peroxide using bromopyrogallol red dye (BPR). The new method can also be used to determine H2O2 concentrations in the 0.1 - 50 mmol L−1 range using a single enzymatic reaction involving H2O2 oxidation of 4-fluorophenol catalyzed by HRP. The methodology could potentially be used to detect a wide range of substrates for which selective oxidase enzymes exist (to generate H2O2), with the high throughput of simple microtiter plate detection scheme. PMID:18480896

  14. Comparison of the Biological Impacts of the Fluoride Compounds by Graphical Risk Visualization Map Technique.

    PubMed

    Usuda, Kan; Kono, Rei; Ueno, Takaaki; Ito, Yuichi; Dote, Tomotaro; Yokoyama, Hirotaka; Kono, Koichi; Tamaki, Junko

    2015-09-01

    Various fluoride compounds are widely used in industry. The present risk assessment study was conducted using a series of inorganic binary fluorides of the type XFn, where X(n) = Na(+), K(+), Li(+), Mg(2+), Ca(2+), Sr(2+), Ba(2+), Al(3+), Nd(3+), La(3+), Ce(3+), Sm(3+), Gd(3+), Y(3+), Yb(2+), and Zn(2+). The aqueous solutions of these salts were orally administrated to 16 experimental groups (one for each of the salts tested). The levels of fluoride, N-acetyl-β-D-glucosaminidase in cumulative 24-h urine samples and creatinine clearance were measured to assess possible acute renal damages. The levels of fluoride, alanine aminotransferase, and aspartate aminotransferase were also determined in serum samples to assess possible acute hepatic damages. The results reveal that sodium fluoride (NaF), potassium fluoride (KF), and zinc fluoride tetrahydrate (ZnF2 (.)4H2O) can carry the fluoride ion into the bloodstream and that it is excreted via urine more readily than the other compounds tested. These fluorides were assigned the highest risk impact factor. Most of the rare earth fluorides are insoluble in water while those groups 2 and 13 of the periodic table are slightly soluble, so that they do not have a significant negative risk. These findings suggest that the biological impact of fluoride depends on the accompanying counter ion and its solubility. The risk map obtained in the present study shows that the graphical visualization map technique employed is a valuable new tool to assess the toxicological risk of chemical compounds.

  15. Geochemical evaluation of fluoride contamination of groundwater in the Thoothukudi District of Tamilnadu, India

    NASA Astrophysics Data System (ADS)

    Singaraja, C.; Chidambaram, S.; Anandhan, P.; Prasanna, M. V.; Thivya, C.; Thilagavathi, R.; Sarathidasan, J.

    2014-09-01

    Fluoride is a chemical element that has been shown to cause significant effects on human health through drinking water. Different forms of fluoride exposure are of importance and have shown to affect the body's fluoride content and thus increasing the risks of fluoride-prone diseases. Fluoride has beneficial effects on teeth; however, low concentrations of fluoride intensify the risk of tooth decay. Fluoride can also be quite detrimental at higher concentrations at skeletal fluorosis. The Thoothukudi District is a hard rock and alluvial plain marked as one of the Fluoride-increase area in Tamilnadu due to occurrence of various rock types including fluoride-bearing minerals. The F- content of groundwater can thus originate from the dissolution of Fluoride-bearing minerals in the bed rock. Hundred representative groundwater samples from Thoothukudi District were collected during two different seasons. Samples were analysed for F-, other major cations and anions. The study area is chiefly composed of hornblende biotite gneiss, charnockite, alluvio marine, fluvial marine and granite with small patches of quartzite and sandstone. Higher concentration of fluoride is observed during pre-monsoon (3.3 mg l-1) compared to the post-monsoon (2.4 mg l-1) due to the dilution effect. Spatial distribution and factor score show that higher concentrations of F- are noted in the north and central part of the study area owing to lithology. Bicarbonate is well correlated with F- which explains that both ions were derived from the weathering. While F- has a very weak correlation with pH which may be due to the increase of alkalinity resulting from the increase of carbonate and bicarbonate ions.

  16. Endemic fluorosis in San Luis Potosi, Mexico. I. Identification of risk factors associated with human exposure to fluoride.

    PubMed

    Grimaldo, M; Borja-Aburto, V H; Ramírez, A L; Ponce, M; Rosas, M; Díaz-Barriga, F

    1995-01-01

    In order to identify risk factors associated with human exposure to fluoride in San Luis Potosi (SLP), Mexico, a biochemical and epidemiological study was carried out in 1992. Results from the analysis of fluoride sources showed that 61% of tap water samples had fluoride levels above the optimal level of 0.7-1.2 ppm. The levels were higher after boiling. In bottled water, fluoride levels ranged from 0.33 to 6.97 ppm. These sources are important since in SLP 82% of the children drink tap water, 31% also drink bottled water, 92% prepare their food with tap water, 44% boiled all the drinking water, and 91% used infant formula reconstituted with boiled water. The prevalence and severity of dental fluorosis in children (11-13 years old) increased as the concentration of water fluoride increased. At levels of fluoride in water lower than 0.7 ppm a prevalence of 69% was found for total dental fluorosis, whereas at levels of fluoride in water higher than 2.0 ppm a prevalence of 98% was found. In the same children, fluoride levels in urine were quantified. The levels increased as the concentration of water fluoride increased. Regressional analysis showed an increment of 0.54 ppm (P < 0.0001) of fluoride in urine for each ppm of fluoride in water. Fluoride urinary levels were higher in samples collected during the afternoon (1800) when compared with sample collected during the morning (1100). Taking together all these results, three risk factors for human exposure to fluoride in SLP can be identified: ambient temperature, boiled water, and food preparation with boiled water. These factors explain the prevalence of dental fluorosis in SLP.

  17. Effect of fluoride gels on microhardness and surface roughness of bleached enamel.

    PubMed

    China, Ana L P; Souza, Nayara M; Gomes, Yasmin do S B de L; Alexandrino, Larissa D; Silva, Cecy M

    2014-01-01

    The effect of bleaching treatments containing added calcium and combined with neutral or acidic fluoride gels on tooth enamel was investigated in vitro through Knoop microhardness (KHN) and surface roughness (SR) measurements. A total of 60 bovine incisors were tested, including 30 for SR measurements and 30 for KHN measurements. The specimens were divided into 12 groups and subjected to a bleaching agent with hydrogen peroxide 35% (Whiteness HP 35% Maxx, FGM) or hydrogen peroxide 35% with calcium (Whiteness HP 35% Blue Calcium, FGM) and a fluoride treatment flugel acidulated phosphate fluoride (APF) or flugel neutral fluoride (NF). Control specimens were submitted to bleaching treatments without fluoride. Microhardness tests were performed using a Knoop indentor. Roughness measurements were obtained using a roughness analyzer. Measurements were obtained before and after treatment. The specimens were stored in distilled water at 37 °C between treatments. The results were analyzed using descriptive and inferential statistics. Treatments using APF combined with 35% HP caused a decrease in microhardness, while NF combined with HP 35% Ca increased the enamel hardness. Fluoride gels did not alter the SR of the bleached enamel. PMID:25419249

  18. Total and Free Fluoride Concentration in Various Brands of Toothpaste Marketed in India

    PubMed Central

    Siddanna, Sunitha

    2015-01-01

    Background For fluoridated toothpaste to be effective in controlling dental caries, an adequate concentration of soluble fluoride must be available in the oral cavity. Aim To determine the total and free fluoride concentration in various brands of toothpaste marketed in India. Materials and Methods Three samples of 12 different toothpastes were purchased from supermarkets in Mysore city, Karnataka, India. Toothpastes were analysed in duplicate using a fluoride ion-specific electrode. The concentration of total fluoride (TF) and total soluble fluoride (TSF) were determined. Results Measured TF was consistent with that declared by the manufacturer in five products. Four toothpastes showed lower TF and two higher TF than declared. Most toothpastes exhibited TSF concentrations similar to the TF content except four samples that displayed considerably lower TSF than TF. Conclusion The measurement of total and free fluoride concentrations of toothpastes available in India showed inhomogenities. Therefore there is a need for stringent regulatory control measures for the determination of fluoride content in toothpastes in developing country like India. PMID:26557607

  19. Geochemical factors controlling the occurrence of high fluoride groundwater in the Nagar Parkar area, Sindh, Pakistan.

    PubMed

    Rafique, Tahir; Naseem, Shahid; Usmani, Tanzil Haider; Bashir, Erum; Khan, Farooque Ahmed; Bhanger, Muhammad Iqbal

    2009-11-15

    Fluoride concentrations in groundwater near Nagar Parkar in the Thar Desert of southeastern Pakistan range from 1.13 to 7.85 mg/l, and roughly 78% of the samples contain fluoride in concentrations that exceed the drinking water standard of 1.5mg/l set by WHO. The groundwater is alkaline (pH 7.1-8.4), brackish (TDS 449-15,933 mg/l), and classified as Na-Cl type water. This prevailing chemical character reflects the influence of saltwater intrusion, high evaporation rates, and ion exchange. Groundwater is also supersaturated with respect to calcite, which promotes the removal of Ca(2+) and HCO(3)(-) from solution. As a result, groundwater is generally undersaturated with respect to fluorite, the mineral that typically controls the upper limit of fluoride concentrations. This study examines a number of geochemical parameters in an effort to discover the controls on fluoride concentrations in groundwater. High fluoride concentrations are associated with high TDS, high pH, high Na concentrations, and high sodium absorption ratios (SAR). This suggests that elevated fluoride levels are the result of enhanced fluorite solubility due to Ca depletion and high ionic strength and the release of fluoride from colloid surfaces under high pH conditions. Contrary to what has been found in other studies, sample depth and water temperature do not appear to have a significant role in the distribution of fluoride within the groundwater.

  20. Geochemical factors controlling the occurrence of high fluoride groundwater in the Nagar Parkar area, Sindh, Pakistan.

    PubMed

    Rafique, Tahir; Naseem, Shahid; Usmani, Tanzil Haider; Bashir, Erum; Khan, Farooque Ahmed; Bhanger, Muhammad Iqbal

    2009-11-15

    Fluoride concentrations in groundwater near Nagar Parkar in the Thar Desert of southeastern Pakistan range from 1.13 to 7.85 mg/l, and roughly 78% of the samples contain fluoride in concentrations that exceed the drinking water standard of 1.5mg/l set by WHO. The groundwater is alkaline (pH 7.1-8.4), brackish (TDS 449-15,933 mg/l), and classified as Na-Cl type water. This prevailing chemical character reflects the influence of saltwater intrusion, high evaporation rates, and ion exchange. Groundwater is also supersaturated with respect to calcite, which promotes the removal of Ca(2+) and HCO(3)(-) from solution. As a result, groundwater is generally undersaturated with respect to fluorite, the mineral that typically controls the upper limit of fluoride concentrations. This study examines a number of geochemical parameters in an effort to discover the controls on fluoride concentrations in groundwater. High fluoride concentrations are associated with high TDS, high pH, high Na concentrations, and high sodium absorption ratios (SAR). This suggests that elevated fluoride levels are the result of enhanced fluorite solubility due to Ca depletion and high ionic strength and the release of fluoride from colloid surfaces under high pH conditions. Contrary to what has been found in other studies, sample depth and water temperature do not appear to have a significant role in the distribution of fluoride within the groundwater. PMID:19586721

  1. Prevalence of fluorosis and identification of fluoride endemic areas in Manur block of Tirunelveli District, Tamil Nadu, South India

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Subarayan Bothi; Viswanathan, Gopalan; Siva Ilango, S.

    2012-12-01

    Prevalence of fluorosis is mainly due to the consumption of more fluoride through drinking water. It is necessary to identify the fluoride endemic areas to adopt remedial measures for the people under the risk of fluorosis. The objectives of this study were to identify the exact location of fluoride endemic areas in Manur block of Tirunelveli District and to estimate fluoride exposure level through drinking water for different age groups. Identification of fluoride endemic areas was performed through Isopleth and Google earth mapping techniques. Fluoride level in drinking water samples was estimated by fluoride ion selective electrode method. A systematic clinical survey conducted in 19 villages of Manur block revealed the rate of prevalence of fluorosis. From this study, it has been found that Alavanthankulam, Melapilliyarkulam, Keezhapilliyarkulam, Nadupilliyarkulam, Keezhathenkalam and Papankulam are the fluoride endemic villages, where the fluoride level in drinking water is above 1 mg/l. Consumption of maximum fluoride exposure levels of 0.30 mg/kg/day for infants, 0.27 mg/kg/day for children and 0.15 mg/kg/day for adults were found among the respective age group people residing in high fluoride endemic area. As compared with adequate intake level of fluoride of 0.01 mg/kg/day for infants and 0.05 mg/kg/day for other age groups, the health risk due to excess fluoride intake to the people of Alavanthankulam and nearby areas has become evident. Hence the people of these areas are advised to consume drinking water with optimal fluoride to avoid further fluorosis risks.

  2. High Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    NASA Astrophysics Data System (ADS)

    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 (< 500mg/l) Ca-Mg-HCO3 dominated water at recharge area in the highlands and escarpments evolve progressively into Ca-Na-HCO3 and Na-Ca-HCO3 type waters along the rift ward groundwater flow paths. These waters finally appear as moderate TDS (mean 960mg/l) Na-HCO3 type and as high 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 (<30mg/l) thermal waters indicated a dilution by cold waters. Laboratory batch leaching experiments showed that fast dissolution of fluoride from the sediment samples suddenly leached into the interacting water at the first one hour and then remain stable throughout the experiment. The concentrations of leached fluoride from the hot spring deposits, the lacustrine sediments, and the pyroclastic rock are usually low (1% of the total or less than

  3. Aquaporin 5 Interacts with Fluoride and Possibly Protects against Caries.

    PubMed

    Anjomshoaa, Ida; Briseño-Ruiz, Jessica; Deeley, Kathleen; Poletta, Fernardo A; Mereb, Juan C; Leite, Aline L; Barreta, Priscila A T M; Silva, Thelma L; Dizak, Piper; Ruff, Timothy; Patir, Asli; Koruyucu, Mine; Abbasoğlu, Zerrin; Casado, Priscila L; Brown, Andrew; Zaky, Samer H; Bayram, Merve; Küchler, Erika C; Cooper, Margaret E; Liu, Kai; Marazita, Mary L; Tanboğa, İlknur; Granjeiro, José M; Seymen, Figen; Castilla, Eduardo E; Orioli, Iêda M; Sfeir, Charles; Owyang, Hongjiao; Buzalaf, Marília A R; Vieira, Alexandre R

    2015-01-01

    Aquaporins (AQP) are water channel proteins and the genes coding for AQP2, AQP5, and AQP6 are clustered in 12q13. Since AQP5 is expressed in serous acinar cells of salivary glands, we investigated its involvement in caries. DNA samples from 1,383 individuals from six groups were studied. Genotypes of eight single nucleotide polymorphisms covering the aquaporin locus were tested for association with caries experience. Interaction with genes involved in enamel formation was tested. The association between enamel microhardness at baseline, after creation of artificial caries lesion, and after exposure to fluoride and the genetic markers in AQP5 was tested. Finally, AQP5 expression in human whole saliva, after exposure to fluoride in a mammary gland cell line, which is known to express AQP5, and in Wistar rats was also verified. Nominal associations were found between caries experience and markers in the AQP5 locus. Since these associations suggested that AQP5 may be inhibited by levels of fluoride in the drinking water that cause fluorosis, we showed that fluoride levels above optimal levels change AQP5 expression in humans, cell lines, and rats. We have shown that AQP5 is involved in the pathogenesis of caries and likely interacts with fluoride. PMID:26630491

  4. Aquaporin 5 Interacts with Fluoride and Possibly Protects against Caries

    PubMed Central

    Deeley, Kathleen; Poletta, Fernardo A.; Mereb, Juan C.; Leite, Aline L.; Barreta, Priscila A. T. M.; Silva, Thelma L.; Dizak, Piper; Ruff, Timothy; Patir, Asli; Koruyucu, Mine; Abbasoğlu, Zerrin; Casado, Priscila L.; Brown, Andrew; Zaky, Samer H.; Bayram, Merve; Küchler, Erika C.; Cooper, Margaret E.; Liu, Kai; Marazita, Mary L.; Tanboğa, İlknur; Granjeiro, José M.; Seymen, Figen; Castilla, Eduardo E.; Orioli, Iêda M.; Sfeir, Charles; Owyang, Hongjiao; Buzalaf, Marília A. R.; Vieira, Alexandre R.

    2015-01-01

    Aquaporins (AQP) are water channel proteins and the genes coding for AQP2, AQP5, and AQP6 are clustered in 12q13. Since AQP5 is expressed in serous acinar cells of salivary glands, we investigated its involvement in caries. DNA samples from 1,383 individuals from six groups were studied. Genotypes of eight single nucleotide polymorphisms covering the aquaporin locus were tested for association with caries experience. Interaction with genes involved in enamel formation was tested. The association between enamel microhardness at baseline, after creation of artificial caries lesion, and after exposure to fluoride and the genetic markers in AQP5 was tested. Finally, AQP5 expression in human whole saliva, after exposure to fluoride in a mammary gland cell line, which is known to express AQP5, and in Wistar rats was also verified. Nominal associations were found between caries experience and markers in the AQP5 locus. Since these associations suggested that AQP5 may be inhibited by levels of fluoride in the drinking water that cause fluorosis, we showed that fluoride levels above optimal levels change AQP5 expression in humans, cell lines, and rats. We have shown that AQP5 is involved in the pathogenesis of caries and likely interacts with fluoride. PMID:26630491

  5. Chronic Fluoride Toxicity: Dental Fluorosis

    PubMed Central

    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

  6. Fluoride varnishes with calcium glycerophosphate: fluoride release and effect on in vitro enamel demineralization.

    PubMed

    Carvalho, Thiago Saads; Peters, Bianca Glerean; Rios, Daniela; Magalhães, Ana Carolina; Sampaio, Fabio Correia; Buzalaf, Marília Afonso Rabelo; Bönecker, Marcelo José Strazzeri

    2015-01-01

    The aims of this study were (1) to assess the amount of fluoride (F) released from varnishes containing calcium glycerophosphate (CaGP) and (2) to assess the effect of the experimental varnishes on in vitro demineralization. Six test groups using 5 varnishes: base varnish (no active ingredients); Duraphat® (2.26% NaF); Duofluorid® (5.63% NaF/CaF2); experimental varnish 1 (1% CaGP/5.63% NaF/CaF2); experimental varnish 2 (5% CaGP/5.63% NaF/CaF2); and no varnish were set up. In stage 1, 60 acrylic blocks were randomly distributed into 6 groups (n = 10). Then 300 µg of each varnish was applied to each block. The blocks were immersed in deionized water, which was changed after 1, 8, 12, 24, 48 and 72 hours. Fluoride concentration in the water was analyzed using a fluoride electrode. In stage 2, 60 bovine enamel samples were distributed into 6 groups (n = 10), and treated with 300 µg of the respective varnish. After 6 h the varnish was removed and the samples were subjected to a 7-day in vitro pH cycle (6 h demineralization/18 h remineralization per day). The demineralization was measured using surface hardness. The results showed that both experimental varnishes released more fluoride than Duofluorid® and Duraphat® (p < 0.05), but Duraphat® showed the best preventive effect by decreasing enamel hardness loss (p < 0.05). Therefore, we conclude that even though (1) the experimental varnishes containing CaGP released greater amounts of F, (2) they did not increase in the preventive effect against enamel demineralization. PMID:26176358

  7. High concentration aqueous sodium fluoride certified reference materials for forensic use certified by complexometric titration.

    PubMed

    Archer, Marcellé; Brits, Martin; Prevoo-Franzsen, Désirée; Quinn, Laura

    2015-04-01

    Sodium fluoride in concentrations of 1 to 2 % is used to prevent the formation of ethanol in blood and urine samples that are to be analysed for ethanol content. The majority of such samples form part of forensic investigations into alleged drunken driving. In South Africa, the laboratory performing the tests is required to prove that the sodium fluoride concentration in the blood samples is above 1 g/100 ml on receipt. This is done by using a fluoride ion-selective electrode calibrated with external aqueous solutions of sodium fluoride. The National Metrology Institute of South Africa (NMISA) prepares sodium fluoride solutions in concentrations from 0.3 to 3.0 g/100 ml. No other certified sodium fluoride reference solutions in these concentrations are available commercially. The sodium fluoride is certified by precipitation of the fluoride as lead chlorofluoride (PbClF) through the addition of a known excess of lead nitrate. The excess lead is back-titrated with ethylenediamine tetraacetic acid (EDTA) using a photometric electrode to detect the endpoint. Aqueous sodium fluoride solutions are prepared and the concentrations verified by the precipitation/back-titration method. This paper shows the application of a classical complexometric method to the certification of reference materials and describes the procedures for the preparation of the sodium fluoride solutions, verification of the concentrations, homogeneity and stability by primary titrimetry. It also briefly covers the calculation of uncertainty, the establishment of traceability and the quality control measures applied to ensure the quality of the certified reference materials (CRMs). PMID:25326884

  8. High concentration aqueous sodium fluoride certified reference materials for forensic use certified by complexometric titration.

    PubMed

    Archer, Marcellé; Brits, Martin; Prevoo-Franzsen, Désirée; Quinn, Laura

    2015-04-01

    Sodium fluoride in concentrations of 1 to 2 % is used to prevent the formation of ethanol in blood and urine samples that are to be analysed for ethanol content. The majority of such samples form part of forensic investigations into alleged drunken driving. In South Africa, the laboratory performing the tests is required to prove that the sodium fluoride concentration in the blood samples is above 1 g/100 ml on receipt. This is done by using a fluoride ion-selective electrode calibrated with external aqueous solutions of sodium fluoride. The National Metrology Institute of South Africa (NMISA) prepares sodium fluoride solutions in concentrations from 0.3 to 3.0 g/100 ml. No other certified sodium fluoride reference solutions in these concentrations are available commercially. The sodium fluoride is certified by precipitation of the fluoride as lead chlorofluoride (PbClF) through the addition of a known excess of lead nitrate. The excess lead is back-titrated with ethylenediamine tetraacetic acid (EDTA) using a photometric electrode to detect the endpoint. Aqueous sodium fluoride solutions are prepared and the concentrations verified by the precipitation/back-titration method. This paper shows the application of a classical complexometric method to the certification of reference materials and describes the procedures for the preparation of the sodium fluoride solutions, verification of the concentrations, homogeneity and stability by primary titrimetry. It also briefly covers the calculation of uncertainty, the establishment of traceability and the quality control measures applied to ensure the quality of the certified reference materials (CRMs).

  9. Fluoride metabolism when added to salt.

    PubMed

    Whitford, Gary M

    2005-01-01

    The purpose of this review is to present the general characteristics of the metabolism of fluoride particularly as it occurs when ingested with fluoridated salt. Following the absorption of salt-borne fluoride from the stomach and intestines, its metabolism is identical to that of water-borne fluoride or other vehicles containing ionized fluoride. Because fluoridated salt is almost always ingested with food, however, absorption from the gastrointestinal tract may be delayed or reduced. Reports dealing with this subject have shown that fluoride absorption is delayed and, therefore, peak plasma concentrations are lower than when fluoride is ingested with water. The amount of ingested fluoride that is finally absorbed, however, is not appreciably affected unless the meal is composed mainly of components with high calcium concentrations. In this case, the extent of absorption can be reduced by as much as 50%. Fluoridated salt is also ingested less frequently than fluoridated water. Data are presented to show that the dose size and frequency of ingestion have only minor effects on fluoride retention in the body and on the concentrations in plasma, bone and enamel. Finally, calculations are presented to show that the risk of acute toxicity from fluoridated salt is virtually non-existent.

  10. Fluoride in drinking water, brick tea infusion and human urine in two counties in Inner Mongolia, China.

    PubMed

    Li, Hai-rong; Liu, Qing-bin; Wang, Wu-yi; Yang, Lin-sheng; Li, Yong-hua; Feng, Fu-jian; Zhao, Xiao-yu; Hou, Kun; Wang, Ge

    2009-08-15

    The objective of this study was to detect the fluoride level in the drinking water and the urine of habitants aged 16-55 years living in Inner Mongolia China. Furthermore, fluoride concentration of the brick tea infusion samples which were drunk by Mongolia herdsmen in everyday life living in SumuErga village of Ejin Horo Banner, Inner Mongolia China was also determined. A total of 117 participants (61 female and 56 male) were recruited from two counties for a cross-sectional study on health effects of chronic fluoride exposure from drinking water and drinking brick tea infusion. The fluoride concentration in drinking water, urine and brick tea infusion samples were determined using fluoride ion selective electrode method obtained from the Ministry of Health of the People's Republic of China. The average fluoride concentration in drinking water samples was 0.32+/-0.01 mg/L at AretengXire town of Ejin Horo Banner, 0.70+/-0.19 mg/L at SumuErga village of Ejin Horo Banner, and 2.68+/-1.15 mg/L at ZhalaiNuoer district of Manzhouli city. The average fluoride concentration in brick tea infusion samples which collected from Mongolia herdsmen at SumuErga village of Ejin Horo Banner was 1.81+/-1.09 mg/L. The average urinary fluoride concentration at AretengXire town of Ejin Horo Banner was 0.59+/-0.48 mg/L, at SumuErga village of Ejin Horo Banner was 1.45+/-0.93 mg/L and at ZhalaiNuoer district of Manzhouli city was 3.06+/-1.53 mg/L. The higher fluoride levels in the urine of participants may be associated to higher fluoride in drinking water at ZhalaiNuoer of Manzhouli city. However, drinking brick tea infusions with higher fluoride may be the cause of the higher fluoride contents in the Mongolia herdsmen's urine.

  11. Fluoride contamination in groundwater in parts of Nalgonda District, Andhra Pradesh, India.

    PubMed

    Brindha, K; Rajesh, R; Murugan, R; Elango, L

    2011-01-01

    Serious problems are faced in several parts of the world due to the presence of high concentration of fluoride in drinking water which causes dental and skeletal fluorosis to humans. Nalgonda district in Andhra Pradesh, India is one such region where high concentration of fluoride is present in groundwater. Since there are no major studies in the recent past, the present study was carried out to understand the present status of groundwater quality in Nalgonda and also to assess the possible causes for high concentration of fluoride in groundwater. Samples from 45 wells were collected once every 2 months and analyzed for fluoride concentration using an ion chromatograph. The fluoride concentration in groundwater of this region ranged from 0.1 to 8.8 mg/l with a mean of 1.3 mg/l. About 52% of the samples collected were suitable for human consumption. However, 18% of the samples were having less than the required limit of 0.6 mg/l, and 30% of the samples possessed high concentration of fluoride, i.e., above 1.5 mg/l. Weathering of rocks and evaporation of groundwater are responsible for high fluoride concentration in groundwater of this area apart from anthropogenic activities including irrigation which accelerates weathering of rocks.

  12. Excellent fluoride decontamination and antibacterial efficacy of Fe-Ca-Zr hybrid metal oxide nanomaterial.

    PubMed

    Dhillon, Ankita; Nair, Manjula; Bhargava, Suresh K; Kumar, Dinesh

    2015-11-01

    The aim of the present study is to develop an efficient nanomaterial for the removal of fluoride and disinfection of harmful bacteria in order to make water potable according to Environmental Protection Agency (EPA) guidelines. Hydrous hybrid Fe-Ca-Zr oxide nanoadsorbent presented a marked fluoride adsorption capacity of 250 mg/g at pH 7.0 (±0.1) much greater than other commercially accessible adsorbents for both synthetic and real water samples. The adsorption isotherms, Freundlich and Dubinin-Radushkevich (D-R) fitted reasonably well fine having high coefficient of regression values. The adsorption of fluoride was established well using pseudo-second-order kinetics. The fluoride loaded adsorbent was efficiently regenerated by using an alkali solution. Interestingly, the developed nanomaterial not only showed excellent fluoride removal capacity but also demonstrated good antibacterial activity against Escherichia coli with IC50 (25 μg/mL). PMID:26196712

  13. Method for the determination of lignin content of a sample by flash pyrolysis in an atmosphere of hydrogen or helium and method therefor

    NASA Technical Reports Server (NTRS)

    Shakkottai, Parthasarathy (Inventor); Kwack, Eug Y. (Inventor); Lawson, Daniel D. (Inventor)

    1991-01-01

    The lignin content of wood, paper pulp or other material containing lignin (such as filter paper soaked in black liquor) is more readily determined by flash pyrolysis of the sample at approximately 550.degree. C. in a reducing atmosphere of hydrogen or in an inert atmosphere of helium followed by a rapid analysis of the product gas by a mass spectrometer. The heated pyrolysis unit as fabricated comprises a small platinum cup welded to an electrically-heated stainless steel ribbon with control means for programmed short duration (1.5 sec, approximately) heating and means for continuous flow of hydrogen or helium. The pyrolysis products enter an electron-ionization mode mass spectrometer for spectral evaluation. Lignin content is obtained from certain ratios of integrated ion currents of many mass spectral lines, the ratios being linearly related to the Kappa number of Klason lignin.

  14. [Natural fluorides. The distinction between technically produced and naturally occurring fluorides in caries prophylaxis].

    PubMed

    Newesely, H

    1977-06-01

    In the controversial discussion of the bio-availability of fluoride in caries prophylaxis by fluoridation, fluorides coming from the geochemical circulation to the biochemical circulation are sometimes differentiated from synthetic fluorides introduced into fluoride medication. The question as to whether such a differentiation is essential can be answered from the physical-chemical point of view. This requires a wide field of scientific research starting with geochemistry and the knowledge of fluoride deposits, sedimentology, hydrology, technology of inorganic and organic fluorine compounds, thermodynamics of dissolved fluorides, up to biocrystallography and biochemistry of fluorine. PMID:267571

  15. Fluoride levels in various black tea, herbal and fruit infusions consumed in Turkey.

    PubMed

    Emekli-Alturfan, Ebru; Yarat, Aysen; Akyuz, Serap

    2009-07-01

    The fluoride contents were determined by ion-selective electrode in 26 black tea samples originally produced in Turkey, Sri Lanka, India and Kenya, and in 14 herbal and seven fruit infusions originated from Turkey. Fluoride content in black tea infusions ranged from 0.57 to 3.72 mg/L after 5 min of brewing. Higher fluoride levels were found in black teas originated from Turkey when compared with teas originated from Sri Lanka. Moreover higher fluoride levels were determined in black tea bags compared with granular and stick-shaped black teas. However, herbal and fruit infusions were characterized by low values of fluoride (0.02-0.04 mg/L) after 5 min of brewing and increasing brewing time to 10 min caused only slight increases in some infusions. As a result, consuming tea infusions prepared from some black tea available in Turkish market, especially black tea bags, in large quantities may lead to exposion to a high amount of fluoride which may cause dental fluorosis. Although fruit and herbal infusions are safer to consume their fluoride contents are too low for caries prevention. In countries such as Turkey where tea is traditionally consumed, the fluoride concentration and daily safety precautions should be indicated on tea products.

  16. Inhibitory Effect of Fluoride on Na+,K+ ATPase Activity in Human Erythrocyte Membrane.

    PubMed

    A, Shashi; G, Meenakshi

    2015-12-01

    The present study was performed to evaluate the role of long-term consumption of excessive fluoride on electrolyte homeostasis and their transporting mechanisms in erythrocytes of subjects afflicted with dental and skeletal fluorosis. A total of 620 adult (20-50 years) Indian residents participated in this study: 258 men and 242 women exposed to high concentrations of fluoride and 120 age and gender-matched control subjects. Erythrocytes were isolated from blood samples, washed, and used for the estimation of intraerythrocyte sodium and potassium concentrations. Na+,K+ ATPase activity was determined spectrophotometrically from a ghost erythrocyte membrane prepared by osmotic lysis. Erythrocyte analytes were correlated with the water and serum fluoride concentrations by Pearson's bivariate correlation and regression analysis. Results indicated a significant increase in intraerythrocyte sodium (F=14306.265, P<0.0001) in subjects from endemic fluorosis study groups as compared to controls. A significant (P<0.05) positive correlation of intracellular sodium was found with water and serum fluoride concentrations. Mean concentration of intraerythrocytic potassium ions showed significant reduction (F=9136.318, P<0.0001) in subjects exposed to fluoride. A significant (P<0.05) negative correlation of potassium ions was noted with water and serum fluoride concentrations. Na+,K+ ATPase activity was significantly declined (F=1572.763, P<0.0001) in subjects exposed to fluoride. A significant (P<0.05) inverse relationship of Na+,K+ ATPase activity was revealed with water and serum fluoride concentrations.

  17. Analysis of hydrogen isotope mixtures

    DOEpatents

    Villa-Aleman, Eliel

    1994-01-01

    An apparatus and method for determining the concentrations of hydrogen isotopes in a sample. Hydrogen in the sample is separated from other elements using a filter selectively permeable to hydrogen. Then the hydrogen is condensed onto a cold finger or cryopump. The cold finger is rotated as pulsed laser energy vaporizes a portion of the condensed hydrogen, forming a packet of molecular hydrogen. The desorbed hydrogen is ionized and admitted into a mass spectrometer for analysis.

  18. Pilot plant processing of sodium bifluoride to sodium fluoride pellets

    SciTech Connect

    Leone, S.M.

    1985-01-25

    Sodium fluoride (NaF) traps in the PGDP purge cascade presently use NaF pellets to remove residual UF{sub 6} from the gas stream. These pellets are procured from ORGDP which converts sodium bifluoride pellets to NaF by thermal decomposition. Discussions of the possibility of no longer producing pellets at ORGDP, due to oven corrosion problems, led to a pilot plant test at PGDP. This test was designed to examine the feasibility of producing the NaF pellets at PGDP in the event that an alternative source of supply became necessary. Satisfactory pellets were produced without difficulty; however, it was determined that the conversion process could not be readily carried out in the existing NaF traps. Construction of a separate facility with provisions to handle the large quantities of hydrogen fluoride (HF) released during the process would be required to produce pellets at the rate needed. 1 fig., 2 tabs.

  19. The effect of fluoride on the developing tooth.

    PubMed

    Robinson, C; Connell, S; Kirkham, J; Brookes, S J; Shore, R C; Smith, A M

    2004-01-01

    This review aims to outline the effects of fluoride on the biological processes involved in the formation of tooth tissues, particularly dental enamel. Attention has been focused on mechanisms which, if compromised, could give rise to dental fluorosis. The literature is extensive and often confusing but a much clearer picture is emerging based on recent more detailed knowledge of odontogenesis. Opacity, characteristic of fluorotic enamel, results from incomplete apatite crystal growth. How this occurs is suggested by other changes brought about by fluoride. Matrix proteins, associated with the mineral phase, normally degraded and removed to permit final crystal growth, are to some extent retained in fluorotic tissue. Fluoride and magnesium concentrations increase while carbonate is reduced. Crystal surface morphology at the nano-scale is altered and functional ameloblast morphology at the maturation stage also changes. Fluoride incorporation into enamel apatite produces more stable crystals. Local supersaturation levels with regard to the fluoridated mineral will also be elevated facilitating crystal growth. Such changes in crystal chemistry and morphology, involving stronger ionic and hydrogen bonds, also lead to greater binding of modulating matrix proteins and proteolytic enzymes. This results in reduced degradation and enhanced retention of protein components in mature tissue. This is most likely responsible for porous fluorotic tissue, since matrix protein removal is necessary for unimpaired crystal growth. To resolve the outstanding problems of the role of cell changes and the precise reasons for protein retention more detailed studies will be required of alterations to cell function, effect on specific protein species and the nano-chemistry of the apatite crystal surfaces.

  20. High-fluoride groundwater.

    PubMed

    Rao, N Subba

    2011-05-01

    Fluoride (F(-)) is essential for normal bone growth, but its higher concentration in the drinking water poses great health problems and fluorosis is common in many parts of India. The present paper deals with the aim of establishment of facts of the chemical characteristics responsible for the higher concentration of F(-) in the groundwater, after understanding the chemical behavior of F(-) in relation to pH, total alkalinity (TA), total hardness (TH), carbonate hardness (CH), non-carbonate hardness (NCH), and excess alkalinity (EA) in the groundwater observed from the known areas of endemic fluorosis zones of Andhra Pradesh that have abundant sources of F(-)-bearing minerals of the Precambrians. The chemical data of the groundwater shows that the pH increases with increase F(-); the concentration of TH is more than the concentration of TA at low F(-) groundwater, the resulting water is represented by NCH; the TH has less concentration compared to TA at high F(-) groundwater, causing the water that is characterized by EA; and the water of both low and high concentrations of F(-) has CH. As a result, the F(-) has a positive relation with pH and TA, and a negative relation with TH. The operating mechanism derived from these observations is that the F(-) is released from the source into the groundwater by geochemical reactions and that the groundwater in its flowpath is subjected to evapotranspiration due to the influence of dry climate, which accelerates a precipitation of CaCO(3) and a reduction of TH, and thereby a dissolution of F(-). Furthermore, the EA in the water activates the alkalinity in the areas of alkaline soils, leading to enrichment of F(-). Therefore, the alkaline condition, with high pH and EA, and low TH, is a more conducive environment for the higher concentration of F(-) in the groundwater.

  1. Fabrication of a miniaturized capillary waveguide integrated fiber-optic sensor for fluoride determination.

    PubMed

    Xiong, Yan; Wang, Chengjie; Tao, Tao; Duan, Ming; Tan, Jun; Wu, Jiayi; Wang, Dong

    2016-05-10

    Fluoride concentration is a key aspect of water quality and essential for human health. Too much or too little fluoride intake from water supplies is harmful to public health. In this study, a capillary waveguide integrated fiber-optic sensor was fabricated for fluoride measurement in water samples. The sensor was modularly designed with three parts, i.e., a light source, capillary flow cell and detector. When light propagated from a light emitting diode (LED) to the capillary waveguide cell through an excitation fiber, it interacted with the sensing reagent, and its intensity changed with different fluoride concentrations. Then, the light propagated to the detector through a detection fiber for absorption determination of fluoride according to Beer's law. This miniaturized sensor showed advantages of fast analysis (9.2 s) and small reagent demand (200 μL) per sample, and it also had a low detection limit (8 ppb) and high selectivity for fluoride determination. The sensor was applied to fluoride determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and ion chromatography, showing agreement and validating the sensor's potential application.

  2. Study of fluoride content in groundwater of Nawa Tehsil in Nagaur, Rajasthan.

    PubMed

    Gautam, Radha; Bhardwaj, Nagendra; Saini, Yashoda

    2011-01-01

    There is a severe fluoride problem in Nawa tehsil of Nagaur district. Villagers are suffering from dental fluorosis and skeletal fluorosis. So an extensive geochemical study of 27 villages of eastern, south-eastern and southern zone of Nawa tehsil was done. Total 46 ground water samples were collected and analyzed for various physicochemical parameters as well as fluoride content. The ground water samples collected in clean polyethylene plastic containers were analyzed for pH, electrical conductivity, total dissolved salts, calcium, magnesium, total hardness, chloride and alkalinity. The fluoride concentration in the three different zones ranged from 0.64 to 14.62 mg l(-1) where 13.04% samples were found within permissible limit while 86.96% had fluoride beyond permissible limit (> 1.5 mg l(-1)). It was found that among the three different zones south-eastern zone was under serious fluoride contamination where fluoride concentration ranged between 1.10 to 14.62 mg l(-1). In the eastern zone fluoride concentration was recorded from 1.52 to 5.13 mg l(-1) whereas in the southern zone it was found between 0.64 to 3.63 mg l(-1).

  3. Fabrication of a miniaturized capillary waveguide integrated fiber-optic sensor for fluoride determination.

    PubMed

    Xiong, Yan; Wang, Chengjie; Tao, Tao; Duan, Ming; Tan, Jun; Wu, Jiayi; Wang, Dong

    2016-05-10

    Fluoride concentration is a key aspect of water quality and essential for human health. Too much or too little fluoride intake from water supplies is harmful to public health. In this study, a capillary waveguide integrated fiber-optic sensor was fabricated for fluoride measurement in water samples. The sensor was modularly designed with three parts, i.e., a light source, capillary flow cell and detector. When light propagated from a light emitting diode (LED) to the capillary waveguide cell through an excitation fiber, it interacted with the sensing reagent, and its intensity changed with different fluoride concentrations. Then, the light propagated to the detector through a detection fiber for absorption determination of fluoride according to Beer's law. This miniaturized sensor showed advantages of fast analysis (9.2 s) and small reagent demand (200 μL) per sample, and it also had a low detection limit (8 ppb) and high selectivity for fluoride determination. The sensor was applied to fluoride determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and ion chromatography, showing agreement and validating the sensor's potential application. PMID:27067512

  4. The Effect of Fluoride in Osteoporosis.

    ERIC Educational Resources Information Center

    Hedlund, L. R.; Gallagher, J. C.

    1987-01-01

    This article discusses the effect of fluoride on bone tissue and the possible role of fluoride in the treatment of osteoporosis. At present, fluoride treatment should be restricted to clinical trials until its risks and benefits have been further evaluated. (Author/MT)

  5. A Manual for Rural School Fluoridation.

    ERIC Educational Resources Information Center

    Sprouse, Larman W.; Brooks, John

    The product of a 1972 Dental Health Branch contract with the U.S. Public Health Service, this manual is designed to aid in the development of school fluoridation programs and presents: background information on general concepts relating to the action of fluoride on teeth; discussions dealing with community and school fluoridation studies; and the…

  6. Historical biomonitoring of fluoride pollution by determining fluoride contents in roe deer (Capreolus capreolus L.) antlers and mandibles in the vicinity of the largest Slovene thermal power plant.

    PubMed

    Jelenko, Ida; Pokorny, Boštjan

    2010-12-15

    Roe deer antlers/mandibles are a useful tool for determination of ambient fluoride pollution. Antlers have a well-defined annual cycle of growth, therefore they represent a natural standardisation of samples during winter months. On the contrary, mandibles accumulate fluorides during the whole life of an organism, thus they reflect aggregated effect of fluoride pollution trough the life-span of an organism. Both tissues are easily available; mandibles are often systematically collected with the purpose of cognitive management and control, and antlers could be gathered from private well-dated hunters' collections. Considering these benefits, fluoride contents were measured in 141 antlers (period 1960-2007) and 220 mandibles (period 1997-2009) of roe deer, shot in the vicinity of the largest Slovene Thermal Power Plant of Šoštanj (ŠTPP) as one of the major sources of fluorides in Slovenia. Fluoride contents in antlers significantly differed among age categories, and ranged from 110 to 1210 mg/kg in yearlings, 130 to 2340 mg/kg in young adults, and 250 to 2590 mg/kg in older adults, respectively. Fluoride levels in mandibles were also significantly different among age categories, and ranged from 30.0 to 227 mg/kg in fawns, 33.8 to 383 mg/kg in yearlings, and 61.5 to 1020 mg/kg in adults, respectively. Comparison of these results with previously reported fluoride contents in antlers and mandibles of roe deer from different areas of Europe revealed that the study area has never been extensively contaminated with fluorides. Moreover, trends of fluoride contents in both tissues confirmed a significant decrease of fluoride pollution in the area after the years 1995 and 2000, when flue-gas cleaning devices were constructed on the ŠTPP. Indeed, highly positive correlations between annual emissions from the ŠTPP and mean annual fluoride contents in antlers/mandibles confirmed that both tissues may be a useful tool for assessing temporal trends in ambient fluoride

  7. Historical biomonitoring of fluoride pollution by determining fluoride contents in roe deer (Capreolus capreolus L.) antlers and mandibles in the vicinity of the largest Slovene thermal power plant.

    PubMed

    Jelenko, Ida; Pokorny, Boštjan

    2010-12-15

    Roe deer antlers/mandibles are a useful tool for determination of ambient fluoride pollution. Antlers have a well-defined annual cycle of growth, therefore they represent a natural standardisation of samples during winter months. On the contrary, mandibles accumulate fluorides during the whole life of an organism, thus they reflect aggregated effect of fluoride pollution trough the life-span of an organism. Both tissues are easily available; mandibles are often systematically collected with the purpose of cognitive management and control, and antlers could be gathered from private well-dated hunters' collections. Considering these benefits, fluoride contents were measured in 141 antlers (period 1960-2007) and 220 mandibles (period 1997-2009) of roe deer, shot in the vicinity of the largest Slovene Thermal Power Plant of Šoštanj (ŠTPP) as one of the major sources of fluorides in Slovenia. Fluoride contents in antlers significantly differed among age categories, and ranged from 110 to 1210 mg/kg in yearlings, 130 to 2340 mg/kg in young adults, and 250 to 2590 mg/kg in older adults, respectively. Fluoride levels in mandibles were also significantly different among age categories, and ranged from 30.0 to 227 mg/kg in fawns, 33.8 to 383 mg/kg in yearlings, and 61.5 to 1020 mg/kg in adults, respectively. Comparison of these results with previously reported fluoride contents in antlers and mandibles of roe deer from different areas of Europe revealed that the study area has never been extensively contaminated with fluorides. Moreover, trends of fluoride contents in both tissues confirmed a significant decrease of fluoride pollution in the area after the years 1995 and 2000, when flue-gas cleaning devices were constructed on the ŠTPP. Indeed, highly positive correlations between annual emissions from the ŠTPP and mean annual fluoride contents in antlers/mandibles confirmed that both tissues may be a useful tool for assessing temporal trends in ambient fluoride

  8. "Borderline" fluorotic region in Serbia: correlations among fluoride in drinking water, biomarkers of exposure and dental fluorosis in schoolchildren.

    PubMed

    Antonijevic, Evica; Mandinic, Zoran; Curcic, Marijana; Djukic-Cosic, Danijela; Milicevic, Nemanja; Ivanovic, Mirjana; Carevic, Momir; Antonijevic, Biljana

    2016-06-01

    This study explores relation between dental fluorosis occurrence in schoolchildren, residents of Ritopek, a small local community near Belgrade, and fluoride exposure via drinking water. Additionally, fluoride levels were determined in children's urine and hair samples, and efforts were made to correlate them with dental fluorosis. Dental fluorosis and caries prevalence were examined in a total of 52 schoolchildren aged 7-15 years (29 boys and 23 girls). Fluoride levels in three types of samples were analyzed using composite fluoride ion-selective electrode. Results showed high prevalence of dental fluorosis (34.6 %) and low prevalence of dental caries (23.1 %, mean DMFT 0.96) among children exposed to wide range of water fluoride levels (0.11-4.14 mg/L, n = 27). About 11 % of water samples exceeded 1.5 mg/L, a drinking-water quality guideline value for fluoride given by the World Health Organization (2006). Fluoride levels in urine and hair samples ranged between 0.07-2.59 (n = 48) and 1.07-19.83 mg/L (n = 33), respectively. Severity of dental fluorosis was positively and linearly correlated with fluoride levels in drinking water (r = 0.79). Fluoride levels in urine and hair were strongly and positively correlated with levels in drinking water (r = 0.92 and 0.94, respectively). Fluoride levels in hair samples appeared to be a potentially promising biomarker of fluoride intake via drinking water on one hand, and severity of dental fluorosis on the other hand. Based on community fluorosis index value of 0.58, dental fluorosis revealed in Ritopek can be considered as "borderline" public health issue.

  9. "Borderline" fluorotic region in Serbia: correlations among fluoride in drinking water, biomarkers of exposure and dental fluorosis in schoolchildren.

    PubMed

    Antonijevic, Evica; Mandinic, Zoran; Curcic, Marijana; Djukic-Cosic, Danijela; Milicevic, Nemanja; Ivanovic, Mirjana; Carevic, Momir; Antonijevic, Biljana

    2016-06-01

    This study explores relation between dental fluorosis occurrence in schoolchildren, residents of Ritopek, a small local community near Belgrade, and fluoride exposure via drinking water. Additionally, fluoride levels were determined in children's urine and hair samples, and efforts were made to correlate them with dental fluorosis. Dental fluorosis and caries prevalence were examined in a total of 52 schoolchildren aged 7-15 years (29 boys and 23 girls). Fluoride levels in three types of samples were analyzed using composite fluoride ion-selective electrode. Results showed high prevalence of dental fluorosis (34.6 %) and low prevalence of dental caries (23.1 %, mean DMFT 0.96) among children exposed to wide range of water fluoride levels (0.11-4.14 mg/L, n = 27). About 11 % of water samples exceeded 1.5 mg/L, a drinking-water quality guideline value for fluoride given by the World Health Organization (2006). Fluoride levels in urine and hair samples ranged between 0.07-2.59 (n = 48) and 1.07-19.83 mg/L (n = 33), respectively. Severity of dental fluorosis was positively and linearly correlated with fluoride levels in drinking water (r = 0.79). Fluoride levels in urine and hair were strongly and positively correlated with levels in drinking water (r = 0.92 and 0.94, respectively). Fluoride levels in hair samples appeared to be a potentially promising biomarker of fluoride intake via drinking water on one hand, and severity of dental fluorosis on the other hand. Based on community fluorosis index value of 0.58, dental fluorosis revealed in Ritopek can be considered as "borderline" public health issue. PMID:26423526

  10. Fluoride distribution and biological availability in the fallout from Mount St. Helens, 18 to 21 May 1980

    SciTech Connect

    Taves, D.R.

    1980-12-19

    Concentrations of fluoride in the ash fallout in central Washington from the 18 May 1980 eruption of Mount St. Helens varied severalfold, but none are high enough to constitute any immediate hazard to animal life. The heaviest fallout (Moses Lake) contained 113 parts per million (ppm) of acid-labile fluoride, but of this only 11 ppm was water-soluble and 20 ppm was available to rats. The fluoride concentrations in the urine of cattle feeding for 4 days on hay contaminated with this ash were essentially normal. Samples of ash from other areas generally had higher concentrations of acid-labile fluoride but lower concentrations of water-soluble fluoride. The concentrations of water-soluble fluoride was inversely correlated with the coarseness of the fallout. 8 references, 1 figure, 1 table.

  11. Fluoride distribution and biological availability in the fallout from mount st. Helens, 18 to 21 may 1980.

    PubMed

    Taves, D R

    1980-12-19

    Concentrations of fluoride in the ash fallout in central Washington from the 18 May 1980 eruption of Mount St. Helens varied severalfold, but none are high enough to constitute any immediate hazard to animal life. The heaviest fallout (Moses Lake) contained 113 parts per million (ppm) of acid-labile fluoride, but of this only 11 ppm was water-soluble and 20 ppm was available to rats. The fluoride concentrations in the urine of cattle feeding for 4 days on hay contaminated with this ash were essentially normal. Samples of ash from other areas generally had higher concentrations of acid-labile fluoride but lower concentrations of water-soluble fluoride. The concentration of water-soluble fluoride was inversely correlated with the coarseness of the fallout. PMID:17817849

  12. METHOD OF PREPARING METAL FLUORIDES

    DOEpatents

    Katz, J.J.; Sheft, I.

    1959-08-11

    A method is presented for preparing the halides of elements which are relatively non-reactive with halogenating agents. The method involves reacting a mixture of an oxygen containing salt of a difficulty halogenated metal with an oxygen containing salt of an easily halogenated metal with a halogenating agent. Accordingly plutonium tetrafluoride is produced by reacting a mixture of plutonium dioxide and uranium octaoxide with bromine trifluoride. The reaction proceeds smoothly at moderate temperatures and the resulting plutonium trifluoride may be readily separated from many impurities which form volatile fluorides by volatilizing these volatile fluorides from the reaction chamber.

  13. Removal of fluoride from aqueous phase by biosorption onto algal biosorbent Spirogyra sp.-IO2: sorption mechanism elucidation.

    PubMed

    Venkata Mohan, S; Ramanaiah, S V; Rajkumar, B; Sarma, P N

    2007-03-22

    This communication presents results pertaining to the adsorptive studies carried out on fluoride removal onto algal biosorbent (Spirogyra IO2). Batch sorption studies were performed and the results revealed that biosorbent demonstrated ability to adsorb the fluoride. Influence of varying the conditions for removal of fluoride, such as the fluoride concentration, the pH of aqueous solution, the dosage of adsorbent, the temperature on removal of fluoride, and the adsorption-desorption studies were investigated. Sorption interaction of fluoride on to algal species obeyed the pseudo first order rate equation. Experimental data showed good fit with the Langmuir's adsorption isotherm model. Fluoride sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at lower pH. Maximum fluoride sorption was observed at operating 30 degrees C operating temperature. Adsorption-desorption of fluoride into inorganic solutions and distilled water was observed and this indicated the combined effect of ion exchange and physical sorption phenomena. Significant changes in the FT-IR spectra was observed after fluoride sorption which is indicative of the participation of surface function groups associated with hydrogen atoms in the carboxylic groups in sorption interaction. From X-ray photoelectron spectroscopy (XPS) analysis a marginal increase in the area for the binding energy peak at 287.4eV was observed which could be due to the formation of -C-F- bonds. Thermogravimetric (TGA) analysis of the fluoride loaded sorbent showed that the biosorbent underwent three steps decomposition process when heated from 25 to 100 degrees C. The maximum weight loss was observed to be between 200 and 400 degrees C and 700 and 800 degrees C.

  14. Methods of using ionic liquids having a fluoride anion as solvents

    SciTech Connect

    Pagoria, Philip; Maiti, Amitesh; Gash, Alexander; Han, Thomas Yong; Orme, Christine; Fried, Laurence

    2011-12-06

    A method in one embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having a fluoride anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of about 90.degree. C. or less during the contacting. A method in another embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having an acetate or formate anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of less than about 90.degree. C. during the contacting.

  15. Binding characteristics of homogeneous molecularly imprinted polymers for acyclovir using an (acceptor-donor-donor)-(donor-acceptor-acceptor) hydrogen-bond strategy, and analytical applications for serum samples.

    PubMed

    Wu, Suqin; Tan, Lei; Wang, Ganquan; Peng, Guiming; Kang, Chengcheng; Tang, Youwen

    2013-04-12

    This paper demonstrates a novel approach to assembling homogeneous molecularly imprinted polymers (MIPs) based on mimicking multiple hydrogen bonds between nucleotide bases by preparing acyclovir (ACV) as a template and using coatings grafted on silica supports. (1)H NMR studies confirmed the AAD-DDA (A for acceptor, D for donor) hydrogen-bond array between template and functional monomer, while the resultant monodisperse molecularly imprinted microspheres (MIMs) were evaluated using a binding experiment, high performance liquid chromatography (HPLC), and solid phase extraction. The Langmuir isothermal model and the Langmuir-Freundlich isothermal model suggest that ACV-MIMs have more homogeneous binding sites than MIPs prepared through normal imprinting. In contrast to previous MIP-HPLC columns, there were no apparent tailings for the ACV peaks, and ACV-MIMs had excellent specific binding properties with a Ka peak of 3.44 × 10(5)M(-1). A complete baseline separation is obtained for ACV and structurally similar compounds. This work also successfully used MIMs as a specific sorbent for capturing ACV from serum samples. The detection limit and mean recovery of ACV was 1.8 ng/mL(-1) and 95.6%, respectively, for molecularly imprinted solid phase extraction coupled with HPLC. To our knowledge, this was the first example of MIPs using AAD-DDA hydrogen bonds.

  16. Automated ion-selective electrode method for determining fluoride in natural waters

    USGS Publications Warehouse

    Erdmann, D.E.

    1975-01-01

    An automated fluoride method which uses AutoAnalyzer modules in conjunction with a fluoride ion-selective electrode was evaluated. The results obtained on 38 natural water samples are in excellent agreement with those determined by a similar manual method (average difference = 0.026 mg/l). An average fluoride concentration of 0.496 mg/l was found when several natural water samples were spiked with 0.50 mg/l fluoride. Aluminum is the only significant interfering substance, and it can be easily tolerated if its concentration does not exceed 2 mg/l. Thirty samples were analyzed per hour over a concentration range of 0-2 mg/l.

  17. Distribution of fluoride in groundwater and its suitability assessment for drinking purpose.

    PubMed

    Ravindra, Khaiwal; Garg, Vinod K

    2006-04-01

    Groundwater samples collected either from the bore-wells (forms a part of municipal water supply) or from the hand pumps (direct consumption) were analysed for fluoride in Hisar city, India. The results indicate considerable variations among the analysed groundwater samples and the concentration of fluoride ranged from 0.03--16.6 mg/l. In most of the groundwater samples the concentration of fluoride was found to be moderately higher, when compared to the WHO standard for drinking water, which may lead to associated health risks in urban population, if the groundwater is being used without proper treatment. Furthermore, it is suggested that the sources of municipal water supply must be established in a region where an adequate level of fluoride was observed.

  18. HYDROGEN GENERATION FROM SLUDGE SAMPLE BOTTLES CAUSED BY RADIOLYSIS AND CHEMISTRY WITH CONCETNRATION DETERMINATION IN A STANDARD WASTE BOX (SWB) OR DRUM FOR TRANSPORT

    SciTech Connect

    RILEY DL; BRIDGES AE; EDWARDS WS

    2010-03-30

    A volume of 600 mL of sludge, in 4.1 L sample bottles (Appendix 7.6), will be placed in either a Super Pig (Ref. 1) or Piglet (Ref. 2, 3) based on shielding requirements (Ref. 4). Two Super Pigs will be placed in a Standard Waste Box (SWB, Ref. 5), as their weight exceeds the capacity of a drum; two Piglets will be placed in a 55-gallon drum (shown in Appendix 7.2). The generation of hydrogen gas through oxidation/corrosion of uranium metal by its reaction with water will be determined and combined with the hydrogen produced by radiolysis. The hydrogen concentration in the 55-gallon drum and SWB will be calculated to show that the lower flammability limit of 5% hydrogen is not reached. The inner layers (i.e., sample bottle, bag and shielded pig) in the SWB and drum will be evaluated to assure no pressurization occurs as the hydrogen vents from the inner containers (e.g., shielded pigs, etc.). The reaction of uranium metal with anoxic liquid water is highly exothermic; the heat of reaction will be combined with the source term decay heat, calculated from Radcalc, to show that the drum and SWB package heat load limits are satisfied. This analysis does five things: (1) Estimates the H{sub 2} generation from the reaction of uranium metal with water; (2) Estimates the H{sub 2} generation from radiolysis (using Radcalc 4.1); (3) Combines both H{sub 2} generation amounts, from Items 1 and 2, and determines the percent concentration of H{sub 2} in the interior of an SWB with two Super Pigs, and the interior of a 55-gallon drum with two Piglets; (4) From the combined gas generation rate, shows that the pressure at internal layers is minimal; and (5) Calculates the maximum thermal load of the package, both from radioactive decay of the source and daughter products as calculated/reported by Radcalc 4.1, and from the exothermic reaction of uranium metal with water.

  19. Evaluation and comparison of the microhardness of enamel after bleaching with fluoride free and fluoride containing carbamide peroxide bleaching agents and post bleaching anticay application: An in vitro study

    PubMed Central

    George, Liza; Baby, Allu; Dhanapal, T. Prasanth; Charlie, K. M.; Joseph, Asha; Varghese, Anjum Anna

    2015-01-01

    Aims and Objectives: The purpose of the study was to evaluate and compare the microhardness of enamel after the application of anticay on bleached enamel with fluoride containing and fluoride free bleaching agent. Materials and Methods: Twenty freshly extracted teeth decoronated and divided mesiodistally into two halves were randomly divided into five groups with 10 samples in each group. The enamel surface was treated as follows: Group 1 - no treatment, Group 2 - fluoride free bleaching agent, Group 3 - fluoride containing bleaching agent, and Group 4 - fluoride free bleaching agent followed by anticay application. The samples were subjected to indentation to test the microhardness using Vicker's hardness analyzer. Conclusion: Enamel microhardness significantly increased in samples where anticay was used after the application of bleaching agent. PMID:26604568

  20. Geochemical controls of high fluoride groundwater in Umarkot Sub-District, Thar Desert, Pakistan.

    PubMed

    Rafique, Tahir; Naseem, Shahid; Ozsvath, David; Hussain, Riaz; Bhanger, Muhammad Iqbal; Usmani, Tanzil Haider

    2015-10-15

    Groundwater samples (n=152) were collected in the Thar Desert of the Umarkot Sub-District, Pakistan to evaluate the geochemical controls on the occurrence of high fluoride (F(-)) levels within the study area. Fluoride concentrations range from 0.06 to 44.4 mg/L, with mean and median values of 5.22 and 4.09 mg/L, respectively; and roughly 84% of the samples contain fluoride concentrations that exceed the 1.5mg/L drinking water standard set by WHO. The overall groundwater quality reflects the influences of silicate mineral weathering and evaporation. Fluoride originates from the weathering of minerals derived from Type-A granite and possibly anion exchange (OH(-) for F(-)) on clays and weathered micas under high pH conditions. High fluoride levels are associated with Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. Depleted calcium levels in groundwater allow higher fluoride concentrations to occur before the solubility limit for fluoride is reached. PMID:26047861

  1. Geochemical controls of high fluoride groundwater in Umarkot Sub-District, Thar Desert, Pakistan.

    PubMed

    Rafique, Tahir; Naseem, Shahid; Ozsvath, David; Hussain, Riaz; Bhanger, Muhammad Iqbal; Usmani, Tanzil Haider

    2015-10-15

    Groundwater samples (n=152) were collected in the Thar Desert of the Umarkot Sub-District, Pakistan to evaluate the geochemical controls on the occurrence of high fluoride (F(-)) levels within the study area. Fluoride concentrations range from 0.06 to 44.4 mg/L, with mean and median values of 5.22 and 4.09 mg/L, respectively; and roughly 84% of the samples contain fluoride concentrations that exceed the 1.5mg/L drinking water standard set by WHO. The overall groundwater quality reflects the influences of silicate mineral weathering and evaporation. Fluoride originates from the weathering of minerals derived from Type-A granite and possibly anion exchange (OH(-) for F(-)) on clays and weathered micas under high pH conditions. High fluoride levels are associated with Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. Depleted calcium levels in groundwater allow higher fluoride concentrations to occur before the solubility limit for fluoride is reached.

  2. The 8-silyloxyquinoline scaffold as a versatile platform for the sensitive detection of aqueous fluoride.

    PubMed

    Zhou, Xinqi; Lai, Rui; Li, Hui; Stains, Cliff I

    2015-04-21

    Utilizing a novel 8-silyloxyquinoline scaffold, we demonstrate the ability to synthesize fluorogenic probes for the sensitive and selective detection of inorganic fluoride (NaF) in aqueous samples. Our initial probe design (2) is capable of detecting inorganic fluoride at levels as low as 3.8 μM (72 ppb) in aqueous solutions, well below PHS recommended levels for drinking water (0.7-1.2 ppm), placing this probe among the most sensitive fluoride sensors reported to date. Furthermore, our results highlight the utility of the readily modifiable 8-silyloxyquinoline scaffold for the design of tailored fluoride sensing platforms. We demonstrate the ability to rationally tune the fluorescence and physical properties of the 8-silyloxyquinoline scaffold, producing a red-shifted fluoride probe (4) capable of detecting 50 μM (0.95 ppm) NaF in aqueous samples using a straightforward test-strip-based assay format. Taken together this work provides a template for the design of fluoride sensors capable of reporting on relevant concentrations of fluoride in the laboratory and in the field.

  3. Modified zirconium-eriochrome cyanine R determination of fluoride

    USGS Publications Warehouse

    Thatcher, L.L.

    1957-01-01

    The Eriochrome Cyanine R method for determining fluoride in natural water has been modified to provide a single, stable reagent solution, eliminate interference from oxidizing agents, extend the concentration range to 3 p.p.m., and extend the phosphate tolerance. Temperature effect was minimized; sulfate error was eliminated by precipitation. The procedure is sufficiently tolerant to interferences found in natural and polluted waters to permit the elimination of prior distillation for most samples. The method has been applied to 500 samples.

  4. Salt fluoridation in Germany since 1991.

    PubMed

    Schulte, Andreas G

    2005-01-01

    Since 1991, fluoridated salt has been on sale in household-size packages in Germany. Potassium or sodium fluoride is added to iodized salt until the fluoride concentration reaches 250 mg/kg. The use of fluoridated salt to prevent caries is officially recommended by the Deutsche Gesellschaft für Zahn-, Mund- und Kieferheilkunde (DGZMK) and several other associations and groups interested in public health. In the course of the past thirteen years, the market share of fluoridated and iodized domestic salt rose to 63.1% in Germany. However, this positive development must not obscure the fact that fluoridated and iodized salt is still not allowed to be used in restaurant or cafeteria kitchens. This restriction now needs to be revoked in view of the fact that many children, adolescents and adults take their main meals in cafeterias or restaurants. Scientific studies have demonstrated beyond doubt that using fluoridated and iodized salt in cafeteria kitchens poses no problem whatever.

  5. The role of fluoride in erosion therapy.

    PubMed

    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.

  6. Special Report: Fluoridation of Water.

    ERIC Educational Resources Information Center

    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)

  7. [Fluoride accumulation and distribution in mulberry insects near fluoride pollution sources].

    PubMed

    Chen, Yuyin; Lu, Shenggao

    2002-01-01

    Fluoride accumulation and the relative fluoride loading of different body parts in wild mulberry silkworm (Bombyx mandarina M.), mulberry geometrid (Pathonandria atrineata B.), and mulberry silkworm (Bombyx mori L.) near fluoride pollution sources were studied. Comparison of the fluoride content of insect bodies and mulberry leaves showed that insects collected from polluted sites had increased fluoride accumulation. The digestive tract of the insect had much higher fluoride content than the other parts of the body and was considered to be the important organ of fluoride accumulation. There were also wide differences in fluoride accumulation between different insect species within the same polluted site. The highly significantly correlation between fluoride contents of wild mulberry silkworm, mulberry geometrid, and mulberry silkworm with that of the mulberry leaves on which they were collected was found.

  8. Fluoride concentration and pH of iced tea products.

    PubMed

    Behrendt, Annekathrin; Oberste, Volker; Wetzel, Willi Eckhard

    2002-01-01

    The objective of this study was to determine the fluoride concentration and pH of 44 iced tea samples and hence to assess the possible role of these beverages as systemic fluoride source as well as their potential cariogenic and erosive character. Ten tea samples were available as a granular instant powder, and 34 as ready-to-drink liquid products. The iced teas contained different types of sugar alone or in combination with maltodextrin, glucose syrup and noncaloric sweeteners. In one product, only acesulfame and aspartame were established. All samples contained lemon juice or citric acid as an additive. The pH ranged from 4.04 to 2.63 and the titrated amount of base to pH 7.0 from 0.75 to 2.39 mmol NaOH/50 ml. The fluoride concentrations measured were <0.6 ppm in 14 products, 0.6-1.0 ppm in 10 products, 1.1-1.5 ppm in 16 products, 1.6-2.0 ppm in 2, and >2.0 ppm in another 2 products. In conclusion, most of the iced teas studied contained considerable fluoride concentrations. If infants ingest larger amounts of them because of their sweet taste, there is a risk of uncontrolled overdosing as a result of additional fluoride intake from other sources at the same time. Furthermore, the majority of the products revealed a highly cariogenic character and finally, all the iced teas appear to be acidic enough to cause dental erosion if these refreshments were excessively consumed from nursing bottles.

  9. Chemistry control and corrosion mitigation of heat transfer salts for the fluoride salt reactor (FHR)

    SciTech Connect

    Kelleher, B. C.; Sellers, S. R.; Anderson, M. H.; Sridharan, K.; Scheele, R. D.

    2012-07-01

    The Molten Salt Reactor Experiment (MSRE) was a prototype nuclear reactor which operated from 1965 to 1969 at Oak Ridge National Laboratory. The MSRE used liquid fluoride salts as a heat transfer fluid and solvent for fluoride based {sup 235}U and {sup 233}U fuel. Extensive research was performed in order to optimize the removal of oxide and metal impurities from the reactor's heat transfer salt, 2LiF-BeF{sub 2} (FLiBe). This was done by sparging a mixture of anhydrous hydrofluoric acid and hydrogen gas through the FLiBe at elevated temperatures. The hydrofluoric acid reacted with oxides and hydroxides, fluorinating them while simultaneously releasing water vapor. Metal impurities such as iron and chromium were reduced by hydrogen gas and filtered out of the salt. By removing these impurities, the corrosion of reactor components was minimized. The Univ. of Wisconsin - Madison is currently researching a new chemical purification process for fluoride salts that make use of a less dangerous cleaning gas, nitrogen trifluoride. Nitrogen trifluoride has been predicted as a superior fluorinating agent for fluoride salts. These purified salts will subsequently be used for static and loop corrosion tests on a variety of reactor materials to ensure materials compatibility for the new FHR designs. Demonstration of chemistry control methodologies along with potential reduction in corrosion is essential for the use of a fluoride salts in a next generator nuclear reactor system. (authors)

  10. Lanthanum fluoride nanoparticles for radiosensitization of tumors

    NASA Astrophysics Data System (ADS)

    Kudinov, Konstantin; Bekah, Devesh; Cooper, Daniel; Shastry, Sathvik; Hill, Colin; Bradforth, Stephen; Nadeau, Jay

    2016-03-01

    Dense inorganic nanoparticles have recently been identified as promising radiosensitizers. In addition to dose enhancement through increased attenuation of ionizing radiation relative to biological tissue, scintillating nanoparticles can transfer energy to coupled photosensitizers to amplify production of reactive oxygen species, as well as provide UVvisible emission for optical imaging. Lanthanum fluoride is a transparent material that is easily prepared as nanocrystals, and which can provide radioluminescence at a number of wavelengths through simple substitution of lanthanum ions with other luminescent lanthanides. We have prepared lanthanum fluoride nanoparticles doped with cerium, terbium, or both, that have good spectral overlap with chlorine6 or Rose Bengal photosensitizer molecules. We have also developed a strategy for stable conjugation of the photosensitizers to the nanoparticle surface, allowing for high energy transfer efficiencies on a per molecule basis. Additionally, we have succeeded in making our conjugates colloidally stable under physiological conditions. Here we present our latest results, using nanoparticles and nanoparticle-photosensitizer conjugates to demonstrate radiation dose enhancement in B16 melanoma cells. The effects of nanoparticle treatment prior to 250 kVp x-ray irradiation were investigated through clonogenic survival assays and cell cycle analysis. Using a custom apparatus, we have also observed scintillation of the nanoparticles and conjugates under the same conditions that the cell samples are irradiated.

  11. Fluoride in groundwater: toxicological exposure and remedies.

    PubMed

    Jha, S K; Singh, R K; Damodaran, T; Mishra, V K; Sharma, D K; Rai, Deepak

    2013-01-01

    Fluoride is a chemical element that is found most frequently in groundwater and has become one of the most important toxicological environmental hazards globally. The occurrence of fluoride in groundwater is due to weathering and leaching of fluoride-bearing minerals from rocks and sediments. Fluoride when ingested in small quantities (<0.5 mg/L) is beneficial in promoting dental health by reducing dental caries, whereas higher concentrations (>1.5 mg/L) may cause fluorosis. It is estimated that about 200 million people, from among 25 nations the world over, may suffer from fluorosis and the causes have been ascribed to fluoride contamination in groundwater including India. High fluoride occurrence in groundwaters is expected from sodium bicarbonate-type water, which is calcium deficient. The alkalinity of water also helps in mobilizing fluoride from fluorite (CaF2). Fluoride exposure in humans is related to (1) fluoride concentration in drinking water, (2) duration of consumption, and (3) climate of the area. In hotter climates where water consumption is greater, exposure doses of fluoride need to be modified based on mean fluoride intake. Various cost-effective and simple procedures for water defluoridation techniques are already known, but the benefits of such techniques have not reached the rural affected population due to limitations. Therefore, there is a need to develop workable strategies to provide fluoride-safe drinking water to rural communities. The study investigated the geochemistry and occurrence of fluoride and its contamination in groundwater, human exposure, various adverse health effects, and possible remedial measures from fluoride toxicity effects.

  12. Comparison of acidulated phosphate fluoride gel and hydrofluoric acid etchants for porcelain-composite repair.

    PubMed

    Tylka, D F; Stewart, G P

    1994-08-01

    Hydrofluoric acid etches porcelain to produce a porous surface visible under scanning electron microscopy when compared to an acidulated phosphate fluoride gel. Some investigators have suggested the greater porosity of the hydrofluoric acid etch produces a greater composite-to-porcelain bond. This investigation tested that assumption with two common fluoride etchants. The etched surfaces were first viewed under scanning electron microscopy to ensure that a characteristic etch was achieved. Both etchants yielded bond strengths that produced cohesive failure of all samples. This suggested that the intraoral use of hydrofluoric acid is no more effective than the less dangerous acidulated phosphate fluoride gel.

  13. Measurement of pH by NMR Spectroscopy in Concentrated Aqueous Fluoride Buffers

    PubMed Central

    Gerken, James B.

    2010-01-01

    An NMR spectroscopic technique has been developed to give rapid, accurate pH measurements on tenth-milliliter samples of concentrated acidic aqueous solutions buffered by fluoride ion in the pH 1.5 – 4.5 range. The fluoride 19F chemical shift has been calibrated as a function of pH at 0.1 and 1.0 M concentration by reference to an internal 3-fluoropyridine standard. Subsequent measurements of fluoride buffer pH required no additives and only two NMR spectra in the presence of an external reference standard. PMID:21278857

  14. Determining the optimal fluoride concentration in drinking water for fluoride endemic regions in South India.

    PubMed

    Viswanathan, Gopalan; Jaswanth, A; Gopalakrishnan, S; Siva Ilango, S; Aditya, G

    2009-10-01

    Fluoride ion in drinking water is known for both beneficial and detrimental effects on health. The prevalence of fluorosis is mainly due to the intake of large quantities of fluoride through drinking water owing to more than 90% bioavailability. The objective of this study is to predict optimal fluoride level in drinking water for fluoride endemic regions by comprising the levels of fluoride and other water quality parameters in drinking water, prevalence of fluorosis, fluoride intake through water, food and beverages such as tea and coffee and also considering the progressive accumulation of fluoride in animal bones, by comparing with non fluoride endemic areas comprise of the same geological features with the aid of regression analysis. Result of this study shows that increase of fluoride level above 1.33 mg/l in drinking water increases the community fluorosis index (CFI) value more than 0.6, an optimum index value above which fluorosis is considered to be a public health problem. Regression plot between water fluoride and bone fluoride levels indicates that, every increase of 0.5mg/l unit of water fluoride level increases the bone fluoride level of 52 mg/kg unit within 2 to 3 years. Furthermore, the consumption of drinking water containing more than 0.65 mg/l of fluoride can raise the total fluoride intake per day more than 4 mg, which is the optimum fluoride dose level recommended for adults by the Agency for Toxic Substances and Disease Registry. From the result, the people in fluoride endemic areas in South India are advised to consume drinking water with fluoride level within the limit of 0.5 to 0.65 mg/l to avoid further fluorosis risk.

  15. Global affordability of fluoride toothpaste

    PubMed Central

    Goldman, Ann S; Yee, Robert; Holmgren, Christopher J; Benzian, Habib

    2008-01-01

    Objective Dental caries remains the most common disease worldwide and the use of fluoride toothpaste is a most effective preventive public health measure to prevent it. Changes in diets following globalization contribute to the development of dental caries in emerging economies. The aim of this paper is to compare the cost and relative affordability of fluoride toothpaste in high-, middle- and low-income countries. The hypothesis is that fluoride toothpaste is not equally affordable in high-, middle- and low-income countries. Methods Data on consumer prices of fluoride toothpastes were obtained from a self-completion questionnaire from 48 countries. The cost of fluoride toothpaste in high-, middle- and low-income countries was compared and related to annual household expenditure as well as to days of work needed to purchase the average annual usage of toothpaste per head. Results The general trend seems to be that the proportion of household expenditure required to purchase the annual dosage of toothpaste increases as the country's per capita household expenditure decreases. While in the UK for the poorest 30% of the population only 0.037 days of household expenditure is needed to purchase the annual average dosage (182.5 g) of the lowest cost toothpaste, 10.75 days are needed in Kenya. The proportion of annual household expenditure ranged from 0.02% in the UK to 4% in Zambia to buy the annual average amount of lowest cost toothpaste per head. Conclusion Significant inequalities in the affordability of this essential preventive care product indicate the necessity for action to make it more affordable. Various measures to improve affordability based on experiences from essential pharmaceuticals are proposed. PMID:18554382

  16. Dipotassium hydrogencarbonate fluoride monohydrate

    PubMed Central

    Kahlenberg, Volker; Schwaier, Timo

    2013-01-01

    Single crystals of the title compound, K2(HCO3)F·H2O, were obtained as a secondary product after performing flux synthesis experiments aimed at the preparation of potassium rare earth silicates. The basic building unit of the structure is an [(HCO3)(H2O)F]2− zigzag chain running parallel to [001]. Both types of anions as well as the water mol­ecules reside on mirror planes perpendicular to [010] at y = 0.25 and y = 0.75, respectively. Linkage between the different constituents of the chains is provided by O—H⋯O and O—H⋯F hydrogen bonding. The K+ cations are located between the chains and are coordinated by two F and five O atoms in form of a distorted monocapped trigonal prism. PMID:23633982

  17. The Effect of Salivary Calcium and Fluoride Toothpaste on the Formation of KOH-Soluble Fluoride: In Vitro Study

    PubMed Central

    Peroš, Kristina; Šutej, Ivana; Rošin-Grget, Kata

    2015-01-01

    Objective The aim of this in vitro preliminary study was to assess the effect of smokers’ saliva (assuming their higher calcium concentration) in combination with fluoridated toothpaste on the enamel uptake of alkali-soluble (KOH-soluble) fluoride. Materials and methods Four enamel slabs were cut from each of 14 impacted third molars and randomly assigned into 4 groups. Unstimulated saliva samples were collected from two age and sex matched volunteers. One of the samples was taken from a heavy smoker and the other sample was taken from a non-smoker. Two groups (A and B) were shaken in saliva (A in smoker's saliva, B in nonsmoker's saliva) for 5 min and then shaken for 3 min in a toothpaste/deionized water slurry (1:3 w/w). One of the groups (group C) received no saliva treatment and was only shaken in toothpaste slurry for 3 min. The treatment was repeated after a 6-hour period. One of the groups (D) served as a control group with no treatment. Results Calcium concentration in the smoker’s saliva was higher than in the nonsmoker’s saliva. The enamel uptake of KOH-soluble fluoride in group A was significantly higher than that in the other two treatment groups, B and C. The enamel uptake of KOH-soluble fluoride in all 3 groups was statistically different from that in the control group. Conclusion These results demonstrate that saliva collected from a heavy smoker, which had higher salivary calcium concentration, enhances enamel uptake of alkali-soluble fluoride and encourages us to conduct a large-scale study. PMID:27688406

  18. Effects of Sodium and Hydrogen Flourides on the Metabolism of Flourine, Calcium, and Phosphorus in Rats

    PubMed Central

    Macuch, P.; Kortus, J.; Balazova, G.; Mayer, J.

    1968-01-01

    Rats given 4 mg. fluoride/kg./day for eight days excreted more calcium and phosphorus and retained less than the controls. In bone ash from rats given different fluoride doses for 40 days the calcium and phosphorus were maximal after a total dose of about 250 μg. fluoride/rat, but fell to subnormal levels after higher doses. The calcium and phosphorus levels in bone ash from rats given 750 μg. fluoride/day fell with the duration of treatment. Rats exposed to 9·4-11·7 μg. hydrogen fluoride/litre air absorbed fluoride rapidly, as shown by increased urinary excretion, by changes in the enamel of the teeth, and by rising fluoride levels in the teeth and bones. Radiological examination, however, showed no gross changes. Urinary excretion increased with exposure time. PMID:5647974

  19. Pyroclastic fluoride in ground waters in some parts of Tadpatri Taluk, Anantapur district, Andhra Pradesh.

    PubMed

    Reddy, N B; Prasad, K S S

    2003-10-01

    Fluorosis is a disease affecting the teeth and bones and caused by excessive ingestion of fluoride through drinking water. Fluoride concentration in ground water samples of the study area varies from 1.2 to 2.1 ppm., which is much above the permissible limit. The probable source of fluoride in ground water is fluoride bearing minerals like apatite, micas and clay minerals etc., present in the country rocks like shales and pyroclastic materials of the study area. The sample survey is carried out to know the incidence of fluorosis in this area which reveals that more than 43% of the inhabitants are affected by dental fluorosis and 0.4% by skeletal fluorosis.

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

    NASA Astrophysics Data System (ADS)

    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

  1. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used... fluoride resins consist of basic resins produced by the polymerization of vinylidene fluoride. (b)...

  2. [Alternative ways of fluoride supplementation in childhood (author's transl)].

    PubMed

    Bergmann, K E; Bergmann, R L

    1977-02-01

    Fluorine is a nutritionally essential trace element. Fluoride concentration in drinking water of West Germany is very low, with rare exceptions. Fluoride intake with food therefore is inadequate. Consequently, for maintenance of normal dental health, fluoride has to be supplemented by some way. A number of methods of fluoride supplementation are being discussed in this paper and compared to drinking waster fluoridation.

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

    PubMed Central

    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

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

    PubMed

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

    2013-11-19

    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, (18)F, 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

  5. Fluoride-induced early teeth wearing in Argentinian cattle.

    PubMed

    Lopez, T A; Busetti, M R; Fort, M C; Bedotti, D O

    1994-09-01

    The relationship between observed early teeth wearing in cattle and the existence of large areas where excess fluoride in underground water prevails in Argentina, but has never been studied. Average values of bone fluoride exceeding 5000 ppm and well water containing up to 10.5 ppm of this element were found in a farm (ETWF) where early teeth wearing is observed, while in a control farm (NETWF), those values were 1480 ppm and 3.0 ppm respectively. Urine samples from animals from the ETWF contained almost 4 times more fluoride than those from the latter. Forage in both farms contained about the same levels of fluoride (15 to 25 ppm). None of the farms was exposed to industrial, volcanic, or geothermal activity. Lactating and adult animals were transferred from one farm to the other. After 30 months, adult animals from the NETWF showed no damage in teeth, while adults from the ETWF continued a rapid teeth wearing. Young animals from the NETWF developed severely damaged permanent teeth, while young animals from the ETWF developed normal teeth. We concluded that the problem exists in the ETWF and being a standard farm, the condition could be extrapolated to other areas.

  6. Assay of fluoride by a novel organic-inorganic mesoporous nano-sized sensor.

    PubMed

    Ma, Qianmin; Lai, Yuming; Gao, Jinwei; Wang, Qianming

    2016-08-01

    In this report, we prepared a novel mesoporous silica nanostructure for selective detection of fluoride through ultraviolet absorption and emission changes. In the sensing system, a silica coupling reagent (3-(triethoxysilyl)propyl isocyanate) linked 1-naphthylamine has been covalently grafted onto the mesopores of inorganic network. These specially designed nanospheres can recognize fluoride from other anions based on hydrogen bond interactions. This approach may provide new opportunities for designing related sensing systems with enhanced physical or chemical properties. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26729521

  7. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, John R.; Dunn, Jerry G.; Avens, Larry R.

    1987-01-01

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF.sub.4 is not further oxidized to AmF.sub.6 by the application of O.sub.2 F at room temperature, while plutonium compounds present in the americium sample are fluorinated to volatile PuF.sub.6, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride.

  8. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, J.R.; Dunn, J.G.; Avens, L.R.

    1987-02-13

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF/sub 4/ is not further oxidized to AmF/sub 6/ by the application of O/sub 2/F at room temperature thereto, while plutonium compounds present in the americium sample are fluorinated to volatile PuF/sub 6/, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride thereof.

  9. Hand-held water fluoride analysis: An accessible caries prevention tool for dental professionals.

    PubMed

    Quock, Ryan L; Yank, Stephanie W; Chan, Jarvis T

    2011-01-01

    This study sought to compare the relative accuracy of a commercially available hand-held water fluoride analysis unit with a standard laboratory bench-top fluoride-specific electrode/millivoltmeter apparatus, with the goal of identifying possible practical applications of the hand-held unit for preventive dentistry. The units analyzed identical gravimetrically prepared fluoride solutions ranging from 0.1 to 4.0 ppm. The average difference between the measurements from the hand-held unit and the nominal values of the fluoride solutions was 0.011 ppm (SD = 0.068), and the average difference between the hand-held unit's measurements and the bench-top unit's measurements was 0.030 ppm (SD = 0.115). T-test analysis demonstrated no statistical difference between measurements from the hand-held unit with either the nominal values of the fluoride solutions or the bench-top unit's measurements. Results indicate that the hand-held water fluoride analysis unit has an appropriate level of accuracy for the measurement of fluoride levels in drinking water samples by dental professionals.

  10. Fluoride contamination in drinking water in rural habitations of northern Rajasthan, India.

    PubMed

    Suthar, Surindra; Garg, Vinod K; Jangir, Sushant; Kaur, Simarjeet; Goswami, Nidhi; Singh, Sushma

    2008-10-01

    This study was carried out to assess the fluoride concentration in groundwater in some villages of northern Rajasthan, India, where groundwater is the main source of drinking water. Water samples collected form deep aquifer based hand-pumps were analysed for fluoride content. Fluoride in presently studied sites was recorded in the ranges of 4.78 and 1.01 mg/l. The average fluoride concentration for this region was recorded 2.82 mg/l. As per the desirable and maximum permissible limit for fluoride in drinking water, determined by WHO or by Bureau of Indian Standards, the groundwater of about 95 of the studied sites is unfit for drinking purposes. Due to the higher fluoride level in drinking water several cases of dental and skeletal fluorosis have appeared at alarming rate in this region. The middle and eastern parts of the Hanumangarh, a northern most district of the state, can be classified as higher risk area for fluorosis; due to relatively high concentrations of fluoride (3-4 mg/l) in groundwater of this region. After evaluating the data of this study it is concluded that there is an instant need to take ameliorative steps in this region to prevent the population from fluorosis.

  11. Occurence and distribution of fluoride in groundwaters of central Rajasthan, India.

    PubMed

    Vikas, C

    2009-07-01

    High fluoride in groundwater has been reported from many parts of India, particularly its impact on human health. Waterborne fluorosis is prevalent in parts of Ajmer and Jaipur districts in central Rajasthan which can be correlated to excessive concentration of the toxic fluoride ions in drinking water. The area, falling under the semiarid terrain of central Rajasthan, is geologically occupied by Precambrian rocks where groundwater occurs under unconfined conditions. Fluoride concentration in shallow aquifer samples of the study area ranges between 0.12 to 16.9 mg/L. Presence of fluoride bearing minerals in the host rock and their interaction with water is considered to be the main cause for fluoride in groundwater. Chemical weathering under arid to semiarid conditions with relatively high alkalinity favours high concentration of fluoride in groundwater, which has resulted in dental and skeletal fluorosis in the study area. The incidence of fluorosis, caused by an excess of fluoride compounds in drinking water, has been rising at an alarming rate in the state. PMID:21117430

  12. Occurence and distribution of fluoride in groundwaters of central Rajasthan, India.

    PubMed

    Vikas, C

    2009-07-01

    High fluoride in groundwater has been reported from many parts of India, particularly its impact on human health. Waterborne fluorosis is prevalent in parts of Ajmer and Jaipur districts in central Rajasthan which can be correlated to excessive concentration of the toxic fluoride ions in drinking water. The area, falling under the semiarid terrain of central Rajasthan, is geologically occupied by Precambrian rocks where groundwater occurs under unconfined conditions. Fluoride concentration in shallow aquifer samples of the study area ranges between 0.12 to 16.9 mg/L. Presence of fluoride bearing minerals in the host rock and their interaction with water is considered to be the main cause for fluoride in groundwater. Chemical weathering under arid to semiarid conditions with relatively high alkalinity favours high concentration of fluoride in groundwater, which has resulted in dental and skeletal fluorosis in the study area. The incidence of fluorosis, caused by an excess of fluoride compounds in drinking water, has been rising at an alarming rate in the state.

  13. A comprehensive study of H emission in a TEA CO2 laser-induced helium gas plasma for highly sensitive analysis of hydrogen in metal samples

    NASA Astrophysics Data System (ADS)

    Lie, Zener Sukra; Khumaeni, Ali; Niki, Hideaki; Kurihara, Kazuyoshi; Kurniawan, Koo Hendrik; Hedwig, Rinda; Fukumoto, Ken-ichi; Kagawa, Kiichiro; Lee, Yong Inn

    2012-07-01

    Our previous work on an innovative method of hydrogen (H) analysis using the specific characteristics of a TEA CO2 laser, "selective detection method of H", has been improved to realize a high H sensitive analysis with a detection limit of several µg/g. For this purpose, first, we clarified the origin of the H emission disturbance coming from H2O molecules; namely, we showed that most of the H emission came from H2O on the metal surface and not from H2O existing in the surrounding gas when we formed a laser-induced gas plasma. Second, the difference in the emission characteristics between the H emission from H2O on the metal surface and H emission from inside in sample was studied to determine the optimum gating time of the optical multi-channel analyzer (OMA). Third, the gas plasma was totally covered by fresh helium gas using a big pipe (5 mm in diameter) and by flowing a high amount of He (10 l/min). Also, we demonstrated that our methods could potentially be applied to H analysis in steel samples, where an H analysis with a sensitivity of less than 1 µg/g is required without employing a heating process, by removing H2O on the sample surface with the aid of defocused TEA CO2 laser irradiation. Thus, we stress that our method can be used for a highly sensitive, in-situ analysis of H for metal samples.

  14. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China.

    PubMed

    Li, Chengcheng; Gao, Xubo; Wang, Yanxin

    2015-03-01

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F(-) concentration of up to 14.1mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F(-) concentrations above the WHO provisional drinking water guideline of 1.5mg/L. Groundwater with high F(-) concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3(-) content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F(-) mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F(-) in groundwater of the intermediate and deep aquifers.

  15. Preparation and characterization of γ-AlOOH @CS magnetic nanoparticle as a novel adsorbent for removing fluoride from drinking water.

    PubMed

    Wan, Zhen; Chen, Wei; Liu, Cheng; Liu, Yu; Dong, Changlong

    2015-04-01

    For this study, a novel adsorbent of γ-AlOOH @CS (pseudoboehmite and chitosan shell) magnetic nanoparticles (ACMN) with magnetic separation capabilities was developed to remove fluoride from drinking water. The adsorbent was first characterized, and then its performance in removing fluoride was evaluated. Kinetic data demonstrated rapid fluoride adsorption with more than 80% fluoride adsorption within the initial 20 min and equilibrium reached in 60 min. Based on the results of kinetic and isotherm models, the fluoride adsorption process on the ACMN's surface was a monolayer adsorption on a homogeneous surface. Thermodynamic parameters presented that the adsorption process is spontaneous and endothermic in nature. The mechanism for the adsorption involved electrostatic interaction and hydrogen bonding. Moreover, the calculated adsorption capacity of the ACMN for fluoride using the Langmuir model was 67.5 mg/g (20°C, pH=7.0±0.1), higher than other fluoride removal adsorbents. This nanoadsorbent performed well over a pH range of 4-10. The study found that PO4(3-) was the co-existing anion most able to hinder the nanoparticle's fluoride adsorption, followed by NO3(-) then Cl(-). Experimental results suggest that ACMN is a promising adsorbent for treating fluoride-contaminated water.

  16. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    DOEpatents

    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.

  17. Fluoride laser crystals: old and new

    NASA Astrophysics Data System (ADS)

    Jenssen, Hans P.; Cassanho, Arlete

    2006-02-01

    The development of oxide and fluoride materials as gain materials of choice for solid state lasers ranges from early materials such as Calcium Fluoride and Calcium Tungstate crystals to the now ubiquitous Nd hosts YLF, YAG and Vanadate. Among Tunable laser materials, MgF II - an early favorite, gave way to superior oxides such as Alexandrite and Ti:Sapphire only to be followed by development of still newer tunable fluoride media, notably, fluoride colquiriites such as Cr-doped LiSAF and LiCaF. Newer fluoride crystals, such as Barium Yttrium Fluoride BaY II F 8 (BYF), KY 3F 10 (KYF) and the tunable Cr doped LiCaGaF 6 are attractive laser materials, but their growth has not been optimized. Key advantages of two of these new crystals are discussed. Crystal growth results for BYF and Cr:LiCaGaF 6 as well as some material characterization are presented.

  18. Comparison of the antimicrobial efficacy of chlorhexidine, sodium fluoride, fluoride with essential oils, alum, green tea, and garlic with lime mouth rinses on cariogenic microbes

    PubMed Central

    Thomas, Ann; Thakur, Sneha; Mhambrey, Sanjana

    2015-01-01

    Background: A number of natural mouth rinse formulations are being proposed as an alternative to the widely used chemical mouth rinses. Objective: To evaluate and compare the antimicrobial efficacy of chlorhexidine (0.2%), sodium fluoride (0.05%), fluoride with essential oils (0.05%), alum (0.02 M), green tea, and garlic with lime mouth rinses against Streptococcus mutans, lactobacilli, and Candida albicans. Materials and Methods: The three microbes were isolated from the saliva samples collected from children with severe early childhood caries. The zone of minimum inhibition was assessed using agar diffusion method. The data were statistically analyzed using SPSS software. Results: Against S. mutans and lactobacilli, chlorhexidine mouth rinse was found to be the most effective as compared to sodium fluoride (P < 0.001, P < 0.001), fluoride with essential oils (P < 0.001, P < 0.001), alum (P < 0.001, P < 0.001), green tea (P < 0.001, P < 0.001), and garlic with lime (P < 0.001, P < 0.001) mouth rinses, respectively. But against C. albicans, garlic with lime mouth rinse was found to be the most effective as compared to chlorhexidine (P < 0.001), sodium fluoride (P < 0.001), fluoride with essential oils (P < 0.001), alum (P < 0.001), and green tea (P < 0.001) mouth rinses. Against S. mutans and lactobacilli, after chlorhexidine mouth rinse, garlic with lime mouth rinse was found to be significantly more effective than sodium fluoride (P = 0.053, P = 0.001), fluoride with essential oils (P < 0.001, P < 0.001), alum (P < 0.001, P < 0.001), and green tea (P < 0.001, P < 0.001) mouth rinses. Conclusion: As a natural mouth rinse, garlic with lime mouth rinse was found to be the most promising. However, further studies are needed in this field. PMID:26312230

  19. Systematic review of water fluoridation

    PubMed Central

    McDonagh, Marian S; Whiting, Penny F; Wilson, Paul M; Sutton, Alex J; Chestnutt, Ivor; Cooper, Jan; Misso, Kate; Bradley, Matthew; Treasure, Elizabeth; Kleijnen, Jos

    2000-01-01

    Objective To review the safety and efficacy of fluoridation of drinking water. Design Search of 25 electronic databases and world wide web. Relevant journals hand searched; further information requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Main outcome measures Decayed, missing, and filled primary/permanent teeth. Proportion of children without caries. Measure of effect was the difference in change in prevalence of caries from baseline to final examination in fluoridated compared with control areas. For potential adverse effects, all outcomes reported were used. Results 214 studies were included. The quality of studies was low to moderate. Water fluoridation was associated with an increased proportion of children without caries and a reduction in the number of teeth affected by caries. The range (median) of mean differences in the proportion of children without caries was −5.0% to 64% (14.6%). The range (median) of mean change in decayed, missing, and filled primary/permanent teeth was 0.5 to 4.4 (2.25) teeth. A dose-dependent increase in dental fluorosis was found. At a fluoride level of 1 ppm an estimated 12.5% (95% confidence interval 7.0% to 21.5%) of exposed people would have fluorosis that they would find aesthetically concerning. Conclusions The evidence of a beneficial reduction in caries should be considered together with the increased prevalence of dental fluorosis. There was no clear evidence of other potential adverse effects. PMID:11021861

  20. Fluoride excretion of adults living in border regions with either water or salt fluoridation.

    PubMed

    Guindy, Joseph S; Gysin, Ralph; Kränzlin, Marius; Gasser, Thomas C; Hauck, Kirsten; Meyer, Jürg

    2006-01-01

    The canton of Basel-Stadt was the only canton in Switzerland which introduced drinking water fluoridation (DWF) at 1 ppm (mg/l). All other cantons have relied on fluoridated domestic salt at 250 ppm F as the main vehicle for basic fluoride exposure. It has been suggested that persons living and working in the DWF areas or persons commuting to the DWF areas may be exposed to higher than optimal doses of fluoride. The objective of this present study was to determine the urinary fluoride excretion of adults living and or working in neighboring areas of either salt or water fluoridation. In this study, 24-hour urine was collected from 69 healthy subjects and tested for fluoride concentration. The mean fluoride concentration for all participants was 0.55 +/- 0.25 ppm (mg/l) ranging from 1.14 to 0.09 ppm. The mean fluoride excretion was 0.95 +/- 0.47 mg F/d ranging from 0.18 to 2.12 mg F/d. The 33 subjects living in a DWF region showed a mean urine fluoride concentration of 0.64 +/- 0.24 ppm (mg/l) and a mean fluoride excretion of 1.14 +/- 0.48 mg F/d. Those 36 subjects living in a region without DWF showed a mean urine fluoride concentration of 0.47 +/- 0.24 ppm (mg/l) and a mean fluoride excretion of 0.78 +/- 0.40 mg F/d. A significant difference between the two means of the groups living in regions with or without DWF was detected when the Mann-Whitney statistical test was applied (p < 0.005). The combined intake of fluoridated drinking water and fluoridated table salt in the sub-group of 11 subjects who commuted showed an overall increase in fluoride urine concentration. The measured values, however, were not significantly different from the other sub-groups.

  1. Fluoride enrichment in groundwater of semi-arid urban area: Khan Younis City, southern Gaza Strip (Palestine)

    NASA Astrophysics Data System (ADS)

    Abu Jabal, Mohamed Shaban; Abustan, Ismail; Rozaimy, Mohd Remy; Al-Najar, Hussam

    2014-12-01

    The aim of this study is to determine fluoride enhancement in the groundwater of semi-arid urban area of Khan Younis City, southern Gaza Strip. Physicochemical data for a total of 200 groundwater samples were analyzed. The fluoride concentrations were varied from 0.3 to 6.45 mg/L with average value of 2.87 mg/L. Correlations between fluorides with other measured ions were relatively observed, negative correlation with calcium and the positive correlation with pH, bicarbonate and sodium increase the dissolution/solubility of fluoride bearing minerals, leading to fluoride leaching into the groundwater. Fluoride enrichment in the groundwater of the area is due to water hydrochemistry, mineral-water interaction (mainly calcite and fluorite), fluorite resulted from fluorapatite dissolution. The saturation indexes evaluation indicated that 42% of the samples are over saturated with respect to calcite and 35.5% under saturated with respect to fluorite, while 40.5% approached equilibrium with respect to both calcite and fluorite. At fluoride concentrations of less than 2.2 mg/L fluorite saturation indexes show under-saturation condition for fluorite and at higher fluoride concentrations show near saturation condition.

  2. [Concentration of fluoride in mixed saliva of patients with end-stage renal disease undergoing renal replacement therapy].

    PubMed

    Gorbaczewski, Andrzej; Buczkowska-Radlińska, Jadwiga; Chlubek, Dariusz; Noceń, Iwona; Samujło, Dorota; Trusewicz, Matylda

    2004-01-01

    This study was carried out on 48 patients with ESRD undergoing hemodialysis treatment (29 males and 19 females, mean age 50.8 years) and renal transplantation (15 females and 33 males, mean age 42.2 years). The results were compared with a group of 44 healthy persons (23 females and 21 males, mean age 49.5 years). The aim of our investigation was to examine the content of fluoride in the mixed unstimulated saliva of the patients undergoing renal replacement therapy and in the control group of healthy persons. We studied the influence of hemodialysis on saliva fluoride levels. Saliva samples were collected by the spitting method according to Navazesh. Samples were collected before and after hemodialysis session and once in graft recipients and controls. Fluoride concentrations were determined with an Orion fluoroselective electrode model 96-09. The fluoride level in healthy persons was 4.92 +/- 2.30 micromol/L. Before hemodialysis, the mean fluoride level was 9.63 +/- 3.90 micromol/L and decreased significantly to 7.52 +/- 2.71 micromol/L after hemodialysis (p < 0.0001). Saliva content of fluorides in patients before and after hemodialysis was significantly higher than in healthy subjects and kidney graft recipients (p < 0.0001). There was no significant difference in fluoride concentration between patients after kidney transplantation and controls. The results suggest the need for individual fluoride supplementation in chronically hemodialysed patients.

  3. Parental preference for fluoride varnish: a new concept in a rapidly developing nation

    PubMed Central

    Hendaus, Mohamed A; Jama, Hibaq A; Siddiqui, Faisal J; Elsiddig, Sohair A; Alhammadi, Ahmed H

    2016-01-01

    Objective The objective of this study was to investigate parental preference for fluoride varnish in a country where the average percentage of dental caries in young children is up to ~73%. Consequently, the aim of this study, despite being a pilot, was to create a nationwide project in the State of Qatar to promote oral health in children. Methods A cross-sectional perspective study was conducted at Hamad Medical Corporation in Qatar. Parents of children aged ≤5 years were offered an interview survey. A total of 200 questionnaires were completed (response rate =100%). The study was conducted between December 1, 2014 and March 30, 2015, and included all children aged >1 year and <5 years who came to the outpatient clinics for well-child and sick visits. We also included children who were admitted to the inpatient wards. Results The mean age of participant children was 2.8±1.1 years. When inquiring regarding parents’ knowledge and awareness of dental health, we found that >90% of families were aware that dental health affects the health of the whole body. The study showed that ~70% of parents were not aware of the existence of fluoride varnish, but would allow a health provider to apply fluoride varnish. Furthermore, ~80% of parents would not stop brushing their child’s teeth and would not skip dentist appointments if varnish was to be applied. Approximately 40% of parents conveyed some concerns regarding the safety of fluoride varnish, despite being considered as a new concept. The main concern was that the child might swallow some of the fluoride. Another important concern expressed by parents was the availability of the fluoride varnish in all clinics. Conclusion The robust positive attitude of parents in this sample suggests that introducing fluoride varnish is feasible and acceptable in our community. Actions to augment fluoride varnish acceptability in the developing world, such as focusing on safety, could be important in the disseminated

  4. Health risk assessment of fluoride in drinking water from Anhui Province in China.

    PubMed

    Gao, Hong-jian; Jin, You-qian; Wei, Jun-ling

    2013-05-01

    This study analyzes the concentrations and health risks of fluoride in 249 drinking water samples collected from different regions of Anhui Province in China. Results indicated that fluoride content in drinking water ranged from 0.12 to 1.94 mg L(-1) (mean = 0.57 mg L(-1)) in the following order: Huaibei plain region > Jianghuai hill region ≈ Dabieshan mountainous region > plain along the Yangtze River region > southern Anhui mountainous region. The fluoride contents were less than 0.50 mg L(-1) in 66.66 % of the drinking water samples, 0.51-1.0 mg L(-1) in 23.29 %, and higher than 1.0 mg L(-1) in 12.04 %. The fluoride levels in some samples were lower than the recommended values for controlling dental caries (0.50-1.0 mg L(-1)). The total fluoride intake from drinking water was between 0.14 and 2.33 mg per day in different regions of the province, supposing an individual consumes 1.2 L of water per day. Therefore, measures should be taken to increase fluoride intake in the Jianghuai hill region, Dabieshan mountainous region, plain along the Yangtze River, and southern Anhui mountainous region to control dental caries. On the other hand, the fluoride levels must be reduced in the Huaibei plain region to decrease endemic fluorosis. The results serve as crucial guidelines for managing fluoride safety in drinking water and controlling endemic fluorosis in different regions of Anhui Province. PMID:22903334

  5. Utility of check dams in dilution of fluoride concentration in ground water and the resultant analysis of blood serum and urine of villagers, Anantapur District, Andhra Pradesh, India.

    PubMed

    Bhagavan, S V B K; Raghu, V

    2005-02-01

    High levels of fluoride (beyond 1.5 ppm) in ground water as source of drinking water are common in many parts of Andhra Pradesh, India, causing fluorosis. The study carried out in endemic Nalgonda District, Andhra Pradesh, has indicated that the fluoride-rich ground water present in the wells located down stream and close to the surface water bodies is getting diluted by the low-fluoride surface water. Encouraged by this result, check dams were constructed upstream of the identified marginally high fluoride bearing ground water zones in Anantapur District to reduce fluoride levels as an alternate solution for safe drinking water. In this paper, an attempt is made to study the utility and effect of these check dams in dilution of fluoride concentration in drinking water and its resultant impact on the health aspects of certain villagers of Anantapur District through the analysis of their blood serum and urine. Ground water samples from three fluoride-affected villages, blood and urine of males and females from the same villages were collected and analyzed for fluoride using ion selective electrode method. The results indicated that the fluoride levels in blood serum and urine of males in the age group of 5-11 years are found to be the highest. The concentration of fluoride in ground water is directly proportional to the concentration of fluoride in blood serum and urine. The concentration of fluoride in ground water with depth of the aquifer is a function of lithology, amount and duration of rainfall, rate of infiltration, level of ground water exploitation in the area etc. The construction of check dams upstream of the identified marginally high fluoride waters will not only cause additional recharge of ground water but also reduces the fluoride concentration eventually improving the health of the villagers.

  6. FLUORIDATION CHEMISTRY: EQUILIBRIA AND KINETICS OF FLUORIDE AND FLUORO-COMPLEXES

    EPA Science Inventory

    The most common fluoridating agents used by major American waterworks are hexafluorosilicic acid (H2SiF6) and sodium hexxafluorosilicate (Na2SiF6). According to the 1992 Water Fluoridation Census where 10,002 utilities responded affirmatively to fluoridating their water, 59
    % ...

  7. PRECIPITATION OF URANIUM PEROXIDE OF LOW FLUORIDE CONTENT FROM SOLUTIONS CONTAINING FLUORIDES

    DOEpatents

    King, E.J.; Clark, H.M.

    1958-08-12

    S>A method is described for the preparation of fluoride free uraniunn peroxide precipitates, even though the solution from which the precipitation is made is contaminated with fluorides. This is accomplished by add ing aluminum ions to the solution, where they complex any fluoride present and prevent its precipitation with the uramum peroxide.

  8. Preliminary Measurements of Oxygen-18 and Hydrogen-2 in Water Samples Collected from a Cloud Forest in Monteverde, Costa Rica

    NASA Astrophysics Data System (ADS)

    Still, C. J.; Foster, P. N.; Pounds, A.; Williams, A.

    2003-12-01

    We collected water samples in August, 2003 from a cloud forest in Monteverde, Costa Rica. This forest is inundated frequently by orographic clouds formed during rapid uplift of trade winds along the Cordillera de Tilaran. Climate observations at Monteverde suggest an overall warming along with intensification of the January-April dry season when convective storms are minimal and orographic cloudwater inputs are most important for the forest ecosystem. This intensification may be driven by uplift of the orographic cloud base above the forest elevation. In order to assess how such changes affect the forest ecosystem, we collected samples during a convective rainstorm, from orographic clouds flowing over the forest, from canopy mosses, and from stream water. The long-term objective of this research is to quantify the influence of orographic clouds on the ecological functioning of this forest. This will include an assessment of cloud water usage by the vegetation using isotopic tracers. We will take advantage of the isotopic offset between cloudwater and convective precipitation to partition water usage by forest vegetation into cloudwater and precipitation inputs on seasonal and interannual bases.

  9. Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

    NASA Astrophysics Data System (ADS)

    Seiler, Ch; Agner, J. A.; Pillet, P.; Merkt, F.

    2016-05-01

    Supersonic beams of hydrogen atoms, prepared selectively in Rydberg-Stark states of principal quantum number n in the range between 25 and 35, have been deflected by {90}\\circ , decelerated and loaded into off-axis electric traps at initial densities of ≈ {10}6 atoms cm-3 and translational temperatures of 150 mK. The ability to confine the atoms spatially was exploited to study their decay by radiative and collisional processes. The evolution of the population of trapped atoms was measured for several milliseconds in dependence of the principal quantum number of the initially prepared states, the initial Rydberg-atom density in the trap, and the temperature of the environment of the trap, which could be varied between 7.5 and 300 K using a cryorefrigerator. At room temperature, the population of trapped Rydberg atoms was found to decay faster than expected on the basis of their natural lifetimes, primarily because of absorption and emission stimulated by the thermal radiation field. At the lowest temperatures investigated experimentally, the decay was found to be multiexponential, with an initial rate scaling as {n}-4 and corresponding closely to the natural lifetimes of the initially prepared Rydberg-Stark states. The decay rate was found to continually decrease over time and to reach an almost n-independent rate of more than (1 ms)-1 after 3 ms. To analyze the experimentally observed decay of the populations of trapped atoms, numerical simulations were performed which included all radiative processes, i.e., spontaneous emission as well as absorption and emission stimulated by the thermal radiation. These simulations, however, systematically underestimated the population of trapped atoms observed after several milliseconds by almost two orders of magnitude, although they reliably predicted the decay rates of the remaining atoms in the trap. The calculations revealed that the atoms that remain in the trap for the longest times have larger absolute values of the

  10. Characterization of the terbium-doped calcium fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Zheleznov, Dmitry S.; Starobor, Aleksey V.; Palashov, Oleg V.

    2015-08-01

    Optical, thermo-optical and magneto-optical characteristics of the terbium-doped (10 at.%) calcium fluoride sample were investigated. It was made the analysis, confirmed the possibility of development of a Faraday isolator and a cryogenic Faraday isolator based on the studied medium, which will provide more than 30 dB isolation ratio of laser radiation in the "eye-safe" wavelength range (1530-1620 nm) at the 5 and 20 kW power, respectively.

  11. Phytotoxicity of sodium fluoride and uptake of fluoride in willow trees.

    PubMed

    Clausen, Lauge Peter Westergaard; Karlson, Ulrich Gosewinkel; Trapp, Stefan

    2015-01-01

    The willow tree (Salix viminalis) toxicity test and a cress seed germination test (Lepidium sativum) were used to determine uptake of F and phytotoxicity of NaF. Concentrations in hydroponic solutions were 0-1000 mg F/L and 0-400 mg F/L in the preliminary and definitive test. A third test was done with soils collected from a fluoride-contaminated site at Fredericia, Denmark. The EC10, EC20 and EC50-values for inhibition of transpiration were determined to 38.0, 59.6 and 128.7 mg F/L, respectively. The toxicity test with soil showed strong inhibition for the sample with the highest fluoride concentration (405 mg free F per kg soil, 75 mg F per L soil solution). The seed germination and root elongation test with cress gave EC10, EC20 and EC50-values of 61.4, 105.0 and 262.8 mg F/L, respectively. At low external concentrations, fluoride was taken up more slowly than water and at high external concentrations at the same velocity. This indicates that an efflux pump becomes overloaded at concentrations above 210 mg F/L. Uptake kinetics were simulated with a non-linear mathematical model, and the Michaelis-Menten parameters were determined to half-saturation constant KM near 2 g F/L and maximum enzymatic removal rate vmax at 9 g/(kg d).

  12. Oxygen and hydrogen stable isotope content in daily-collected precipitation samples at Dome C, East Antarctica

    NASA Astrophysics Data System (ADS)

    Dreossi, Giuliano; Stenni, Barbara; Del Guasta, Massimo; Bonazza, Mattia; Grigioni, Paolo; Karlicek, Daniele; Mognato, Riccardo; Scarchilli, Claudio; Turchetti, Filippo; Zannoni, Daniele

    2016-04-01

    Antarctic ice cores allow to obtain exceptional past climate records, thanks to their water stable isotope content, which provides integrated tracers of the atmospheric water cycle and local climate. Low accumulation sites of the East Antarctic plateau provide the oldest ice core records, with the record-breaking EPICA Dome C drilling covering the last eight climate cycles. However, the isotope-temperature relationship, commonly used to derive the temperature, may be characterized by significant geographical and temporal variations. Moreover, post-depositional effects may further complicate the climate interpretation. A continuous series of precipitation data is needed in order to gain a better understanding of the factors affecting the water stable isotopes in Antarctic precipitation at a specific site. In this study, we use the first and so-far only multi-year series of daily precipitation sampling and isotope measurements from the French-Italian Concordia Station, located at Dome C in East Antarctica (75°06'S 123°21'E; elevation: 3233 m a.s.l.; mean annual temperature: -54.5°C; snow accumulation rate: 25 kg m-2 yr-1), where the oldest deep Antarctic ice core has been retrieved. Surface air temperature data have been provided by the US automatic weather station (AWS), placed 1.5 km away from the base, while tropospheric temperature profiles are obtained by means of a radiosonde, launched once per day by the IPEV/Italian Antarctic Meteo-climatological Observatory. The new dataset also enables us for the first time to study the isotope-temperature relationship distinguishing between different types of precipitation, namely diamond dust, hoar frost and snowfall, identified by the observations carried out by the winter-over personnel collecting the snow samples. Here we present the complete data series of water stable isotopes in precipitation at Dome C spanning the time period from 2008 to 2014, in the framework of the PNRA PRE-REC project.

  13. Study of changes in phosphate, calcium and fluoride ions in plaque and saliva after the administration of a fluoride mouth rinse.

    PubMed

    Poureslami, H R; Torkzadeh, M; Sefadini, M R

    2007-01-01

    In this study, the effects of 0.2% sodium fluoride mouthwash solution on calcium, phosphate and fluoride ion contents of saliva and microbial plaque was assessed. Fourteen volunteer students (7-12 years of age) of a boarding educational centre in Kerman City (Iran) were selected and under defined conditions, their saliva and plaque samples were collected. The concentrations of fluoride, calcium and phosphate ions of the samples were determined, and after 14 days, under the same conditions, the students were asked to rinse their mouth with 0.2% sodium fluoride mouthwash solution. The second set of saliva and plaque samples were collected and the concentrations of the ions were determined. Data was analyzed using paired t-test and the results were presented as tables. P < 0.05 was considered as statistically significant. After using 0.2% sodium fluoride mouthwash solution, a significant increase was observed in the F 2 ion concentration both plaque ( P P < 0.000) of all the studied subjects, while the concentration of phosphate decreased in both saliva and plaque; however, this decrease was significant only in plaque ( P < 0.01). The calcium ion concentration decreased in both plaque and saliva; however, in none of them, the decrease was significant ( P> 0.09 and P> 0.2, respectively).

  14. Efficacy of calcium- and fluoride-containing materials for the remineralization of primary teeth with early enamel lesion.

    PubMed

    Memarpour, Mahtab; Soltanimehr, Elham; Sattarahmady, Naghmeh

    2015-09-01

    The aim of the study was to determine the efficacy of different products containing fluoride, calcium and phosphate for enamel remineralization in eroded primary teeth. A total of 90 sound primary canine teeth were randomly divided into 5 groups of 18 teeth each: 1) control (polished enamel), 2) 5% DuraShield sodium fluoride varnish, 3) 500 ppm fluoridated toothpaste, 4) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) cream, and 5) Clinpro White varnish containing functionalized tri-calcium phosphate (fTCP). Enamel microhardness (EMH) was measured in all samples before and after demineralization and after 28 days of remineralization. Also 8 samples in groups 2 to 5 and four samples of sound and demineralized enamel were examined with atomic force microscopy (AFM). All data were analyzed with one-way ANOVA (p<0.05). Mean microhardness of demineralized enamel was significantly lower than in enamel at baseline (p<0.001). Remineralization significantly increased microharness in groups 2 to 5 compared to the control group (p<0.001). Percent EMH after remineralization with CPP-ACP was significantly higher than after fTCP (p=0.029), toothpaste (p< 0.001) or fluoride varnish (p<0.001); however, there was no significant difference between toothpaste and fluoride varnish (p=0.062). Microhardness increased more after fTCP treatment than after treatment with sodium fluoride varnish (p<0.001) or fluoridated toothpaste (p=0.045). AFM images showed that enamel roughness decreased most after treatment with fTCP, followed by CPP-ACP, toothpaste and fluoride varnish. The efficacy of CPP-ACP cream for remineralizing eroded enamel was greater than fluoride toothpaste, fluoride varnish or fTCP varnish. PMID:26179280

  15. Efficacy of calcium- and fluoride-containing materials for the remineralization of primary teeth with early enamel lesion.

    PubMed

    Memarpour, Mahtab; Soltanimehr, Elham; Sattarahmady, Naghmeh

    2015-09-01

    The aim of the study was to determine the efficacy of different products containing fluoride, calcium and phosphate for enamel remineralization in eroded primary teeth. A total of 90 sound primary canine teeth were randomly divided into 5 groups of 18 teeth each: 1) control (polished enamel), 2) 5% DuraShield sodium fluoride varnish, 3) 500 ppm fluoridated toothpaste, 4) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) cream, and 5) Clinpro White varnish containing functionalized tri-calcium phosphate (fTCP). Enamel microhardness (EMH) was measured in all samples before and after demineralization and after 28 days of remineralization. Also 8 samples in groups 2 to 5 and four samples of sound and demineralized enamel were examined with atomic force microscopy (AFM). All data were analyzed with one-way ANOVA (p<0.05). Mean microhardness of demineralized enamel was significantly lower than in enamel at baseline (p<0.001). Remineralization significantly increased microharness in groups 2 to 5 compared to the control group (p<0.001). Percent EMH after remineralization with CPP-ACP was significantly higher than after fTCP (p=0.029), toothpaste (p< 0.001) or fluoride varnish (p<0.001); however, there was no significant difference between toothpaste and fluoride varnish (p=0.062). Microhardness increased more after fTCP treatment than after treatment with sodium fluoride varnish (p<0.001) or fluoridated toothpaste (p=0.045). AFM images showed that enamel roughness decreased most after treatment with fTCP, followed by CPP-ACP, toothpaste and fluoride varnish. The efficacy of CPP-ACP cream for remineralizing eroded enamel was greater than fluoride toothpaste, fluoride varnish or fTCP varnish.

  16. [Fluoride concentration in bottled water on the market in the municipality of São Paulo].

    PubMed

    Grec, Roberto Henrique da Costa; de Moura, Patrícia Garcia; Pessan, Juliano Pelim; Ramires, Irene; Costa, Beatriz; Buzalaf, Marília Afonso Rabelo

    2008-02-01

    The objective of the study was to evaluate the fluoride concentration in bottled water available on the market, in comparison with the values printed on the bottle label. Two hundred and twenty-nine water samples were collected from 35 brands available in several supermarkets, grocery stores and snack bars with high turnover in different regions of the municipality of São Paulo, Southeastern Brazil, in 2006. Fluoride concentrations were determined by duplicate analysis using an ion-specific electrode. The fluoride concentrations ranged from 0.01 to 2.04 mg/l, with significant differences between the values stipulated on labels and those found in the analyses. These results emphasize the importance of controls over fluoride levels in bottled water enforced by the sanitary surveillance agency. PMID:18200355

  17. Identification of fluoride contamination with the interaction of physico-chemical characteristics in groundwater of Jodhpur (India).

    PubMed

    Modi, A N; Kumar, Pushpendra

    2012-10-01

    A hydrogeochemical investigation has been carried out in Jodhpur district of western Rajasthan in India. The investigated area has been classified into four types with reference to concentration of F(-) prescribed for drinking: low-F(-) (< 1.0 mgl(-1)), moderate-F(-) (1.0-1.50 mgl(-1)) , high-F(-) (1.5-3.0 mgl-(1)) and very high-F(-) ( > 3.0 mgl(-1)). Twenty three percent of the total groundwater samples belong to the very high-F(-) category, Twenty two percent samples belong to the high-F(-) category, Thirty four percent samples belong to the moderate-F(-) category and twenty one percent samples belong to the low-F(-) category. The correlation study suggests a positive correlation (r = 0.396) between the pH and fluoride concentration, indicating that higher alkalinity of the water promotes the leaching of fluoride and thus affect the concentration of fluoride in groundwaters. Highest positive correlation coefficient was observed between fluoride and alkalinity (r = 0.516) indicating that alkalinity favors the higher values of fluoride in the study area. The regression equations have been developed by taking fluoride as dependent variable and other water quality parameters as independent variable. Possible sources of fluoride (F(-)) are weathering and leaching of F(-) bearing minerals under the alkaline environment. Arid environment, high rate of evapotranspiration and longer residence time of waters in the aquifer zone are the supplementary factors to further increase the F(-) content in the ground waters.

  18. Fluoride coatings make effective lubricants in molten sodium environment

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Coating bearing surfaces with calcium fluoride-barium fluoride film provides effective lubrication against sliding friction in molten sodium and other severe environments at high and low temperatures.

  19. Stability of fluoride complex with silica and its distribution in natural water systems

    USGS Publications Warehouse

    Roberson, C.E.; Barnes, R.B.

    1978-01-01

    Fluoride reacts with silicic acid to form SiF2-6. A fluoride electrode was used to obtain an equilibrium constant of 1030.18 for the reaction:Si(OH) 0 6 + 6F-+4H+ = SiF 2- 6 + 4H2O at 25??C. Although there may be some experimental evidence for existence of traces of species containing less than six F- ions per silicon (n = 6), the species SiF2-6 predominates for n values from about 0.1 to 6. Silicic-acid complexing with fluoride is important only in solutions which have rather low pH and low concentrations of other cations which compete with silicon for fluoride. Computations for cold volcanic condensates from Hawaii indicate that for some samples much of the silicon is complexed by fluoride as SiF2-6. However, in most cooled acidic natural water samples Al and Fe are more important than Si in complexing fluoride. ?? 1978.

  20. Topical oral cavity pharmacokinetic modeling of a stannous fluoride dentifrice: an unusual two compartment model.

    PubMed

    Scott, Douglas C; Coggan, John W; Cruze, Charles A; He, Tao; Johnson, Robert D

    2009-10-01

    A pharmacokinetic model was developed describing the pharmacokinetics of stannous fluoride in human subjects after oral topical application of a stannous fluoride dentifrice. Twenty subjects participated in an investigation of an experimental dentifrice. Subjects rinsed their mouths with the experimental dentifrice slurry. Saliva and plaque samples were obtained from the subjects at various times up to 6 h after administration. Samples were analyzed for total tin content, used as an analytical marker for the active stannous fluoride ingredient, using a graphite furnace atomic absorption spectrometer. The modeling indicates that there is an obvious kinetic relationship between saliva and plaque compartments and that stannous fluoride is very well retained in and slowly released from plaque (and oral surfaces) into saliva. Additionally, both compartments are simultaneously loaded during administration unlike typical systemic drug behavior, and the elimination rate "constant" from the central compartment (saliva) changes due to changes in salivary flow. Stannous fluoride is cleared from saliva rapidly but very well retained in gingival plaque. The model with simultaneous loading of plaque and saliva describes these observations and may account for the prolonged antiplaque and antigingivitis benefits of stannous fluoride.

  1. Distribution of fluoride in groundwater of Maku area, northwest of Iran

    NASA Astrophysics Data System (ADS)

    Asghari Moghaddam, Asghar; Fijani, Elham

    2008-11-01

    High fluoride groundwater occurs in Maku area, in the north of West Azarbaijan province, northwest of Iran. Groundwater is the main source of drinking water for the area residents. Groundwater samples were collected from 72 selected points including 40 basaltic and 32 nonbasaltic springs and wells, in two stages, during June and August 2006. The areas with high fluoride concentrations have been identified, and the possible causes for its variation have been investigated. Regional hydrogeochemical investigation indicates that water-rock interaction is probably the main reason for the high concentration of ions in groundwater. The concentration of F- in groundwater is positively correlated with that of HCO3 - and Na+, indicating that groundwater with high HCO3 - and Na+ concentrations help to dissolve some fluoride-rich minerals. All of the water samples, collected from the basaltic areas do not meet the water quality standards for fluoride concentration and some other parameters. Hence, it is not suitable for consumption without any prior treatment. Inhabitants of the area that obtain their drinking water supplies from basaltic springs and wells are suffering from dental fluorosis. The population of the study area is at a high risk due to excessive fluoride intake especially when they are unaware of the amount of fluoride being ingested due to lack of awareness.

  2. Non-enzymatic amperometric detection of hydrogen peroxide in human blood serum samples using a modified silver nanowire electrode.

    PubMed

    Thirumalraj, Balamurugan; Zhao, Duo-Han; Chen, Shen-Ming; Palanisamy, Selvakumar

    2016-05-15

    In this paper, we report a highly sensitive amperometric H2O2 sensor based on silver nanowires (AgNWs) modified screen printed carbon electrode. The AgNWs were synthesized using polyol method. The synthesized AgNWs were characterized by scanning electron microscopy, UV-vis spectroscopy and X-ray diffraction techniques. The average diameter and length of the synthesized AgNWs were found as 86±5 and 385nm, respectively. Under optimum conditions, the AgNWs modified electrode shows a stable amperometric response for H2O2 and was linear over the concentrations ranging from 0.3 to 704.8μM. The non-enzymatic sensor showed a high sensitivity of 662.6μAmM(-1)cm(-2) with a detection limit of 29nM. The response time of the sensor was found as 2s. Furthermore, the AgNWs modified electrode exhibited a good recovery of H2O2 (94.3%) in the human blood serum samples.

  3. Quantitative determination of fluoride as a major pollutant in the emissions from the thermal treatment of clayey raw materials.

    PubMed

    Zannini, Paolo

    2002-01-01

    Three clayey raw materials for production of traditional ceramics, all with medium to high fluorine content, have been investigated for determining their attitude to fluoride emission during firing, at varying parameters of the firing cycle, maximum firing temperature included, and in the presence or in the absence of calcium carbonate either added to the sample or naturally present in it. Different analytical methods for the determination of fluoride have been tested, together with different sample preparation procedures aimed to obtain minimum loss of fluoride in the pre-treatment step.

  4. Effect of Fluoride, Casein Phosphopeptide–Amorphous Calcium Phosphate and Casein Phosphopeptide–Amorphous Calcium Phosphate Fluoride on Enamel Surface Microhardness After Microabrasion: An in Vitro Study

    PubMed Central

    Ahmadi Zenouz, Ghazaleh; Ezoji, Fariba; Khafri, Soraya

    2015-01-01

    Objectives: This study aimed to assess the effect of applying casein phosphopeptide– amorphous calcium phosphate (CPP-ACP) paste, casein phosphopeptide–amorphous calcium phosphate fluoride (CPP-ACPF) paste and sodium fluoride gel on surface microhardness of enamel after microabrasion. Materials and Methods: Thirty freshly extracted human premolars were selected. All samples were subjected to hardness indentations made with the Vickers hardness machine and the average value was recorded as the initial surface microhardness. The specimens were then randomly divided into three groups (n=10) of CPP-ACPF, fluoride and CPPACP. The teeth were micro-abraded with Opalustre. Microhardness test was performed to assess the post-abrasion hardness. Three remineralization modalities were performed on samples of each group. The enamel surface microhardness measurements were performed. To compare the difference between groups, the rehardening and softening values were defined. One-way ANOVA and Tukey’s post hoc test at a significance level of 5% were used for statistical analysis. Results: The mean microhardness value (MMV) had a significant decrease after microabrasion from baseline. The MMV had a significant increase after remineralization in all groups. The MMV of CPP-ACPF group was significantly more than that of fluoride group (P=0.027). The rehardening value of fluoride group was significantly more than that of other groups (P<0.001). Conclusion: All the remineralizing agents were effective for rehardening the enamel after microabrasion. The CPP-ACP and CPP-ACPF pastes are effective, but to a lesser extent than neutral sodium fluoride gel in remineralizing enamel surface. Incorporation of fluoride to CPP-ACP formulation does not provide any additional remineralizing potential. PMID:27252753

  5. Luminescence from Edge Fracture in Shocked Lithium Fluoride Crystals

    SciTech Connect

    Turley, W. D.; Stevens, G. D.; Capelle, G. A.; Grover, M.; Holtkamp, D. B.; LaLone, B. M.; Veeser, L. R.

    2013-01-01

    Light emitted from a [100] lithium fluoride crystal was characterized under shock wave compression to 28GPa followed by complete stress release at the edges. The light was examined using time-gated optical spectrometry and imaging, time-resolved optical emission measurements, and hydrodynamic modeling. The shock arrival at the circumference of the crystal was delayed relative to the center so that the two regions could be studied at different times. The majority of the light emission originated when the shock waves released at the circumference of the crystal. Unlike previously reported results for shocked lithium fluoride, we found that the light spectrum is not strictly broad band, but has spectral lines associated with atomic lithium in addition to a broad band background. Also, the emission spectrum depends strongly on the gas surrounding the sample. Based on our observations, the line emission appears to be related to fracture of the lithium fluoride crystal from the shock wave releasing at the edges. Experimenters frequently utilize lithium fluoride crystals as transparent windows for observing shock compressed samples. Because of the experimental geometries used, the shock wave in such cases often reaches the circumference of the window at nearly the same moment as when it reaches the center of the sample-window interface. Light generated at the circumference could contaminate the measurement at the interface when this light scatters into the observed region. This background light may be reduced or avoided using experimental geometries which delay the arrival of the shock wave at the edges of the crystal.

  6. Evaluation of Effect of Brushite-Calcite and Two Indigenous Herbs in Removal of Fluoride from Water

    PubMed Central

    Naveenkumar, Puvvadi Gopalakrishna; Prashant, Gouder Manjunath; Sakeenabi, Basha; Allamaprabhu; Vijetha, Kothyala

    2016-01-01

    Introduction The acceptable concentration of fluoride in drinking water is 1.5mg/l. Excess fluoride in drinking water causes fluorosis. Fluorosis is an important public health problem in India. Several treatment technologies suggested in the past for removing excess fluoride generated and causes various chemical byproductswhich are hazardous to public. In recent years, there has been a resurgence of interest to use natural materials due to cost and associated health and environmental concerns of synthetic organic polymers and inorganic chemicals. Aim The aim of this study was to evaluate and compare the defluoridating capability of the brushite-calcite with that of two indigenous herbs, tulsi and wheat grass. Materials and Methods One gram of brushite-calcite combination, tulsi and wheat grass were separately added to 10 containers, each containing 1.0 l of prepared distilled water with a fluoride concentration of 5ppm and naturally fluoridated water at 2ppm. Half of the samples were boiled for one minute in a domestic electric kettle for one minute and allowed to cool. The remaining half of the samples was left un-boiled. Fluoride concentration in all the samples was assessed at the end of 30 minutes and 24 hours using fluoride ion selective electrode method. Data was analyzed using unpaired t-test and one-way ANOVA. Results For water with 2ppm and 5ppm fluoride, brushite-calcite had shown highest de-fluoridation capacity (p=0.001) at the end of both 30 minutes and 24 hours in boiled samples whereas tulsi (p=0.001) was most effective in un-boiled samples. Conclusion The results of the study suggest that tulsi can be used for domestic water defluoridation as it is economic, safe and effective. PMID:27504417

  7. Interaction between a transition-metal fluoride and a transition-metal hydride: water-mediated hydrofluoric acid evolution following fluoride solvation.

    PubMed

    Chierotti, Michele R; Rossin, Andrea; Gobetto, Roberto; Peruzzini, Maurizio

    2013-11-01

    The reaction between the nickel(II) PCP pincer fluoride complex ((tBu)PCP)Ni(F) [(tBu)PCP = 2,6-C6H3(CH2P(t)Bu2)2] and the tungsten(II) carbonyl hydride CpW(H)(CO)3 (Cp = η(5)-C5H5(-)) leads to hydrofluoric acid evolution and formation of the bimetallic isocarbonylic species [CpW(CO)2(μ-κ,C:κ,O-CO)···Ni((tBu)PCP)]. The process has been monitored through multinuclear ((19)F, (31)P{(1)H}, (1)H) variable-temperature NMR spectroscopy, collecting (19)F T1 data values for a fluoride ligand bound to a transition metal. The extremely short relaxation time (minimum value of 13 ms at 193 K) is ascribed to the large chemical shift anisotropy of the Ni-F bond (688 ppm). The in-depth NMR analysis has revealed that the fluoride-hydride interaction is not direct but water-mediated, at odds with what was previously observed for the "hydride-hydride" case ((tBu)PCP)Ni(H)/CpW(H)(CO)3. Kinetic measurements have unveiled that the first step of the overall mechanism is thought to be solvation of the fluoride ligand (as a result of Ni-F···H2O hydrogen bonding), while further reaction of the solvated fluoride with CpW(H)(CO)3 is extremely slow and competes with the side reaction of fluoride replacement by a water molecule on the nickel center to form the [((tBu)PCP)Ni(H2O)](+) aquo species. Finally, density functional theory analysis of the solvation process through a discrete + continuum model has been accomplished, at the M06//6-31+G(d,p) level of theory, to support the mechanistic hypothesis.

  8. The Pivotal Role of Alumina Pore Structure in HF Capture and Fluoride Return in Aluminum Reduction

    NASA Astrophysics Data System (ADS)

    McIntosh, Grant J.; Agbenyegah, Gordon E. K.; Hyland, Margaret M.; Metson, James B.

    2016-09-01

    Fluoride emissions during primary aluminum production are mitigated by dry scrubbing on alumina which, as the metal feedstock, also returns fluoride to the pots. This ensures stable pot operation and maintains process efficiency but requires careful optimization of alumina for both fluoride capture and solubility. The Brunauer-Emmett-Teller (BET) surface area of 70-80 m2 g-1 is currently accepted. However, this does not account for pore accessibility. We demonstrate using industry-sourced data that pores <3.5 nm are not correlated with fluoride return. Reconstructing alumina pore size distributions (PSDs) following hydrogen fluoride (HF) adsorption shows surface area is not lost by pore diameter shrinkage, but by blocking the internal porosity. However, this alone cannot explain this 3.5 nm threshold. We show this is a consequence of surface diffusion-based inhibition with surface chemistry probably playing an integral role. We advocate new surface area estimates for alumina which account for pore accessibility by explicitly ignoring <3.5 nm pores.

  9. The Pivotal Role of Alumina Pore Structure in HF Capture and Fluoride Return in Aluminum Reduction

    NASA Astrophysics Data System (ADS)

    McIntosh, Grant J.; Agbenyegah, Gordon E. K.; Hyland, Margaret M.; Metson, James B.

    2016-07-01

    Fluoride emissions during primary aluminum production are mitigated by dry scrubbing on alumina which, as the metal feedstock, also returns fluoride to the pots. This ensures stable pot operation and maintains process efficiency but requires careful optimization of alumina for both fluoride capture and solubility. The Brunauer-Emmett-Teller (BET) surface area of 70-80 m2 g-1 is currently accepted. However, this does not account for pore accessibility. We demonstrate using industry-sourced data that pores <3.5 nm are not correlated with fluoride return. Reconstructing alumina pore size distributions (PSDs) following hydrogen fluoride (HF) adsorption shows surface area is not lost by pore diameter shrinkage, but by blocking the internal porosity. However, this alone cannot explain this 3.5 nm threshold. We show this is a consequence of surface diffusion-based inhibition with surface chemistry probably playing an integral role. We advocate new surface area estimates for alumina which account for pore accessibility by explicitly ignoring <3.5 nm pores.

  10. Comparative Evaluation of Longevity of Fluoride Release From three Different Fluoride Varnishes – An Invitro Study

    PubMed Central

    Roshan, NM; Poornima, P; Nagaveni, NB; Neena, IE; Bharath, KP

    2016-01-01

    Introduction Fluoride varnishes play a pivotal role in inhibition of dental caries by increasing remineralization. Aim To determine the longevity of fluoride release from 3 different fluoride varnishes over a period of time through salivary fluoride estimation. Materials and Methods Twenty four extracted human deciduous anterior teeth were divided into four groups, i.e., ClinproTM XT, Flouritop SR, Flourprotector and Control group. Fluoride varnishes were applied on 3mm x 3mm window on labial surface of the teeth and then the teeth were immersed and stored in artificial saliva. The concentration of fluoride in ppm was measured after 1 week, 1 month, 3 months and 6 months. Fluoride release at each time interval for different groups was statistically analyzed using ANOVA and Post Hoc Tukey’s test. Results Although all the fluoride varnishes released fluoride, with greatest release observed during 1st week by Fluoritop SR (66.92±16.30ppm), ClinproTM XT Varnish released consistently and substantially more fluoride than Fluoritop SR and Fluorprotector during 6 months analysis (p<0.05). Fluorprotector showed the lowest rate of F release among all the groups compared. Conclusion Over a period of 6 months ClinproTM XT Varnish released consistently and substantially more fluoride than other tested products. PMID:27656559

  11. Differences in loosely bound fluoride formation and anticaries effect of resin-based fluoride varnishes.

    PubMed

    Maas, Jorge R S; Junior, Italo M Faraco; Lodi, Carolina S; Delbem, Alberto C B

    2013-05-01

    OBJECTIVE.  Our in vitro study evaluated calcium fluoride formation in enamel and the anticaries effect of seven resin-based varnishes under cariogenic challenge. METHODS.  Enamel blocks were subjected to pH cycling. The experimental groups received fluoride varnish application, the positive control received topical fluoride gel treatment, and the negative control did not receive any treatment. The pH cycling surface hardness (SH1 ) and integrated loss of subsurface hardness (ΔKHN) were then determined. We measured the amount of fluoride released into the demineralizing and remineralizing (DE-RE) solutions used in pH cycling. The fluoride concentration in the enamel was determined 24 h after application of the products as loosely bound fluoride and firmly bound fluoride. RESULTS.  Higher deposits of loosely bound fluoride were observed for Duofluorid, followed by Biophat. For Duraphat, Bifluorid, Duraflur, and Duofluorid, no difference was observed in the SH1 and ΔKHN values, with the lowest mineral loss compared to the other groups. The Bifluorid and Duofluorid groups released high fluoride amounts into the DE-RE, and statistically significant difference was noted between them. CONCLUSIONS.  The anticaries effect showed no correlation with higher deposited fluoride amounts, resin type, or fluoride source.

  12. Fluoride Concentration in Dentin of Exfoliated Primary Teeth as a Biomarker for Cumulative Fluoride Exposure

    PubMed Central

    dela Cruz, G.G.; Rozier, R.G.; Bawden, J.W.

    2008-01-01

    A biomarker for lifetime fluoride exposure would facilitate population-based research and policy making but currently does not exist. This study examined the suitability of primary tooth dentin as a biomarker by comparing dentin fluoride concentration and fluoride exposures. Ninety-nine children's exfoliated primary teeth were collected from 2 fluoridated and 2 fluoride-deficient communities in North Carolina. Coronal dentin was isolated by microdissection and fluoride concentration assayed using the microdiffusion, ion-specific electrode technique. Information on children's fluoride exposures since birth from drinking water, toothpaste, supplements, rinses, food and beverages was collected by a self-reported questionnaire administered to caregivers. Only a small portion of the variance (10%) in incisor dentin fluoride (mean 792, SD 402 mg/kg) was accounted for by the best linear regression model as evaluated by the adjusted R2. A moderate portion of the variance (60%) of molar dentin fluoride (mean 768, SD 489 mg/kg) was predicted by dietary fluoride supplement exposures, community of residence, and frequent tea consumption. Results for molars suggest that primary tooth dentin concentration may prove to be a satisfactory biomarker for fluoride exposure. PMID:18832828

  13. Fluoride concentration in dentin of exfoliated primary teeth as a biomarker for cumulative fluoride exposure.

    PubMed

    dela Cruz, G G; Rozier, R G; Bawden, J W

    2008-01-01

    A biomarker for lifetime fluoride exposure would facilitate population-based research and policy making but currently does not exist. This study examined the suitability of primary tooth dentin as a biomarker by comparing dentin fluoride concentration and fluoride exposures. Ninety-nine children's exfoliated primary teeth were collected from 2 fluoridated and 2 fluoride-deficient communities in North Carolina. Coronal dentin was isolated by microdissection and fluoride concentration assayed using the microdiffusion, ion-specific electrode technique. Information on children's fluoride exposures since birth from drinking water, toothpaste, supplements, rinses, food and beverages was collected by a self-reported questionnaire administered to caregivers. Only a small portion of the variance (10%) in incisor dentin fluoride (mean 792, SD 402 mg/kg) was accounted for by the best linear regression model as evaluated by the adjusted R(2). A moderate portion of the variance (60%) of molar dentin fluoride (mean 768, SD 489 mg/kg) was predicted by dietary fluoride supplement exposures, community of residence, and frequent tea consumption. Results for molars suggest that primary tooth dentin concentration may prove to be a satisfactory biomarker for fluoride exposure.

  14. The effect of fluoride contents in fluoridated hydroxyapatite on osteoblast behavior.

    PubMed

    Qu, Haibo; Wei, Mei

    2006-01-01

    Fluoridated hydroxyapatite (FHA) discs with various fluoride contents (0-0.567 mol F(-)/mol) [corrected] have been used to investigate the effect of fluoride content on osteoblastic cell behavior. SAOS-3 rat osteosarcoma cells were cultured on FHA discs for different time periods. The cell behavior was examined in terms of cell attachment, proliferation, morphology and differentiation. The fluoride content in FHA discs strongly affected the cell activities. More cell attachment and proliferation were observed on the fluoride-containing FHA discs than on pure hydroxyapatite (HA). The fluoride content also affected the differentiation behavior of osteoblastic cells. Cells on FHA discs demonstrated a higher alkaline phosphatase (ALP) activity than those on pure HA after 2 [corrected] weeks of culturing. These results suggested that fluoride ions have a significant impact on different osteoblastic cell activities.

  15. Southern hemisphere ground based measurements of Carbonyl Fluoride (COF2) and Hydrogen Fluoride (HF): Partitioning between Fluoride reservoir species

    NASA Technical Reports Server (NTRS)

    Reisinger, Andreas R.; Jones, Nicholas B.; Matthews, W. Andrew; Rinsland, Curtis P.

    1994-01-01

    We report infrared ground based total column measurements of the stratospheric fluorine reservoir gases COF2 and HF above Lauder, New Zealand (45 deg S, 167.8 deg E) obtained between April 1993 and January 1994. The average retrieved COF2 and HF total columns are 2.81(+/- 0.56) x 10(exp 14) and 9.91(+/- 1.09) x 10(exp 14) molecules/sq cm respectively. The daily average COF2 and HF columns are correlated; this correlation is likely the result of dynamics. The average HF/COF2 column ratio on days with measurements of both HF and COF2 is 3.63 (+/- 0.55). Comparison of this ratio with model calculations implies that the quantum yield for COF2 photolysis is near unity. Our measured COF2 columns are higher than all previously reported values, but inconsistencies among the earlier measurements and uncertainty in the latitudinal gradient of the COF2 column preclude an accurate determination of the long-term COF2 trend.

  16. Crystallinity and solubility behavior of iron-containing fluoridated hydroxyapatites.

    PubMed

    Okazaki, M; Takahashi, J; Kimura, H

    1986-09-01

    Iron-containing fluoridated hydroxyapatites with various fluoride contents were synthesized at 80 degrees C and pH 7.4 using FeCl2 X nH2O as a source of iron. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a-Axis dimensions of Fe-containing apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. All Fe-containing fluoridated apatites were less well crystallized than Fe-free fluoridated apatites previously reported, although with increasing degree of fluoridation, the crystallinity behavior of the former apatites appeared analogous to that of the latter apatites. In contrast to this inhibited crystallinity behavior, the apparent solubility of Fe-containing fluoridated apatites decreased more than that of Fe-free fluoridated apatites at low fluoride content.

  17. A calcium prerinse required to form calcium fluoride in plaque from a sodium fluoride rinse.

    PubMed

    Vogel, G L; Tenuta, L M A; Schumacher, G E; Chow, L C

    2014-01-01

    The purpose of this study is to determine whether a calcium (Ca) prerinse used before a 228 µg/g (ppm) fluoride (F) rinse would induce the formation of 'calcium fluoride-like' (CaF2-like) deposits in human dental plaque. Sixty minutes after the use of the Ca prerinse/F rinse, plaque samples were collected from 10 volunteers, homogenized, and split into 2 aliquots. The plaque mass from one aliquot was then extracted with a 'plaque-like' solution that extracted all the CaF2-like deposits. The total F in both aliquots was then determined and compared. The results demonstrated that, as in previous studies, the Ca prerinse induced large increases in plaque fluid and total plaque F. However, unlike previous results without the Ca prerinse, 30% of the plaque F deposits were CaF2 or CaF2-like. Given that maintaining an elevated F concentration in the vicinity of a developing lesion may play an important role in the cariostatic effect of this ion, and the potential advantages of CaF2-like deposits as an F source, these results suggest that a Ca prerinse may increase the cariostatic effect of topical agents.

  18. Fluoride dentifrices: current status and prospects.

    PubMed

    Mellberg, J R

    1991-02-01

    Toothpastes have developed from the poorly effective formulations using incompatible abrasive systems to the highly effective products now being given credit for the decline in dental caries in most developed countries. The earliest toothpastes used sodium fluoride but this was soon replaced by stannous fluoride, sodium monofluorophosphate and amine fluoride. Monofluorophosphate has the advantage that it is compatible with a wide variety of abrasive systems. Although most toothpastes world-wide currently contain monofluorophosphate, sodium fluoride formulations are growing in availability because of the development of compatible abrasives. Clinical caries trials have indicated that, with proper formulation, there is little or no difference in effectiveness among toothpastes prepared with different fluoride agents, but that increasing the fluoride concentration will enhance the anti-caries effect. The addition of other active agents to fluoride toothpaste has been a relatively recent occurrence, and it is important to be assured that they do not interfere with the anti-caries activity of fluoride. Pyrophosphate, a calculus control agent, is one additive that was considered to be a potential problem; however, human and animal tests have shown that both caries and calculus inhibiting effects can be obtained from a single formulation. With the use of modern methodology to evaluate toothpaste formulations before clinical trials, many new products containing anti-calculus and other agents will probably become available in the coming years.

  19. Method of making porous ceramic fluoride

    DOEpatents

    Reiner, Robert H.; Holcombe, Cressie E.

    1990-01-01

    A process for making a porous ceramic composite where fumed silica particles are coated with a nitrate, preferably aluminum nitrate. Next the nitrate is converted to an oxide and formed into a desired configuration. This configuration is heated to convert the oxide to an oxide silicate which is then react with HF, resulting in the fluoride ceramic, preferably aluminum fluoride.

  20. Welsh water should reinstate fluoridation on Anglesey.

    PubMed

    Hulse, G; Kenrick, A; Thomas, C H; Thomas, A; Davies, D J; Lennon, M A

    1995-01-21

    In 1992, Welsh Water withdrew the successful water fluoridation scheme on Anglesey. Despite evidence of the benefits of water fluoridation and the rise in number of children with tooth decay since the scheme's withdrawal, Welsh Water is still not prepared to re-establish the scheme.

  1. The Fluoride Content of Yerba Mate Depending on the Country of Origin and the Conditions of the Infusion.

    PubMed

    Łukomska, A; Jakubczyk, K; Maciejewska, D; Baranowska-Bosiacka, I; Janda, K; Goschorska, M; Chlubek, D; Bosiacka, B; Gutowska, I

    2015-10-01

    There are many reports of the positive effect of yerba mate on the human body. Elemental composition analysis of yerba mate revealed the presence of many microelements and macroelements, but there is no literature data referencing the content and the effect of the method of preparing the yerba mate infusion on the amount of released fluoride and thus the amount of this element supplied to the human body. Therefore, in the traditional way (cold and hot), we prepared infusions of yerba mate from different countries and determined in samples content of fluoride using potentiometric method. Hot infusions resulted in statistically significant (p = 0.03) increases in the amount of fluoride released from the dried material to the water, compared to brewing with water at room temperature. The successive refills of hot water also resulted in a release of the same amount of fluoride, although smaller than the infusion with water at room temperature (at the third refill, it was statistically significantly smaller at p = 0.003). With an increase in the number of hot water refills, the amount of fluoride released from the sample portion significantly decreased. Similar results were recorded when analyzing samples depending on the country of origin. The amount of fluoride released into the water differed statistically significantly depending on the country of origin. The most fluoride was determined in the infusions of yerba mate from Argentina and the least in infusions from Paraguay.

  2. The Fluoride Content of Yerba Mate Depending on the Country of Origin and the Conditions of the Infusion.

    PubMed

    Łukomska, A; Jakubczyk, K; Maciejewska, D; Baranowska-Bosiacka, I; Janda, K; Goschorska, M; Chlubek, D; Bosiacka, B; Gutowska, I

    2015-10-01

    There are many reports of the positive effect of yerba mate on the human body. Elemental composition analysis of yerba mate revealed the presence of many microelements and macroelements, but there is no literature data referencing the content and the effect of the method of preparing the yerba mate infusion on the amount of released fluoride and thus the amount of this element supplied to the human body. Therefore, in the traditional way (cold and hot), we prepared infusions of yerba mate from different countries and determined in samples content of fluoride using potentiometric method. Hot infusions resulted in statistically significant (p = 0.03) increases in the amount of fluoride released from the dried material to the water, compared to brewing with water at room temperature. The successive refills of hot water also resulted in a release of the same amount of fluoride, although smaller than the infusion with water at room temperature (at the third refill, it was statistically significantly smaller at p = 0.003). With an increase in the number of hot water refills, the amount of fluoride released from the sample portion significantly decreased. Similar results were recorded when analyzing samples depending on the country of origin. The amount of fluoride released into the water differed statistically significantly depending on the country of origin. The most fluoride was determined in the infusions of yerba mate from Argentina and the least in infusions from Paraguay. PMID:25774045

  3. Effects of enamel matrix genes on dental caries are moderated by fluoride exposures.

    PubMed

    Shaffer, John R; Carlson, Jenna C; Stanley, Brooklyn O C; Feingold, Eleanor; Cooper, Margaret; Vanyukov, Michael M; Maher, Brion S; Slayton, Rebecca L; Willing, Marcia C; Reis, Steven E; McNeil, Daniel W; Crout, Richard J; Weyant, Robert J; Levy, Steven M; Vieira, Alexandre R; Marazita, Mary L

    2015-02-01

    Dental caries (tooth decay) is the most common chronic disease, worldwide, affecting most children and adults. Though dental caries is highly heritable, few caries-related genes have been discovered. We investigated whether 18 genetic variants in the group of non-amelogenin enamel matrix genes (AMBN, ENAM, TUFT1, and TFIP11) were associated with dental caries experience in 13 age- and race-stratified samples from six parent studies (N = 3,600). Linear regression was used to model genetic associations and test gene-by-fluoride interaction effects for two sources of fluoride: daily tooth brushing and home water fluoride concentration. Meta-analysis was used to combine results across five child and eight adult samples. We observed the statistically significant association of rs2337359 upstream of TUFT1 with dental caries experience via meta-analysis across adult samples (p < 0.002) and the suggestive association for multiple variants in TFIP11 across child samples (p < 0.05). Moreover, we discovered two genetic variants (rs2337359 upstream of TUFT1 and missense rs7439186 in AMBN) involved in gene-by-fluoride interactions. For each interaction, participants with the risk allele/genotype exhibited greater dental caries experience only if they were not exposed to the source of fluoride. Altogether, these results confirm that variation in enamel matrix genes contributes to individual differences in dental caries liability, and demonstrate that the effects of these genes may be moderated by protective fluoride exposures. In short, genes may exert greater influence on dental caries in unprotected environments, or equivalently, the protective effects of fluoride may obviate the effects of genetic risk alleles.

  4. Plant tissue hybrid electrode for determination of phosphate and fluoride

    SciTech Connect

    Schubert, F.; Renneberg, R.; Scheller, F.W.; Kirstein, L.

    1984-08-01

    A biosensor for inorganic phosphate and fluoride has been developed by coupling a potato (Solanum tuberosum) tissue slice and immobilized glucose oxidase with a Clark oxygen electrode. Measurement is based on the inhibition by either ion of potato acid phosphates catalyzed glucose 6-phosphate hydrolysis. The precision is 1.7% and 6.5% and the lower detection limit 2.5 X 10/sup -5/ M and 1 X 10/sup -4/ M for phosphate and fluoride, respectively. For phosphate determination the hybrid sensor is stable for 28 days or 300 assays. With a higher limit of detection the sensor can be applied in a commercial enzyme electrode based device. Its application for phosphate determination in fertilizer and urine samples is described.

  5. High Temperature Fluoride Salt Test Loop

    SciTech Connect

    Aaron, Adam M.; Cunningham, Richard Burns; Fugate, David L.; Holcomb, David Eugene; Kisner, Roger A.; Peretz, Fred J.; Robb, Kevin R.; Wilson, Dane F.; Yoder, Jr, Graydon L.

    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

  6. Recent advancements in fluoride: A systematic review.

    PubMed

    Bansal, Ankita; Ingle, Navin Anand; Kaur, Navpreet; Ingle, Ekta

    2015-01-01

    To review advancements of fluoride in dentistry, a search of 21 electronic databases and World Wide Web was conducted. Relevant journals were hand searched and further information was requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Fluoride has become an important tool in preventive dentistry. Current research is focused on the development of strategies to improve fluoride efficacy. Fluoride therapy in the form of varnish, gel, mouth rinse, or toothpaste has been used extensively as a caries-preventive intervention for over three decades. The purpose of this review is to inform the reader about new research related to the use of fluoride for the prevention of dental caries. PMID:26539383

  7. Recent advancements in fluoride: A systematic review

    PubMed Central

    Bansal, Ankita; Ingle, Navin Anand; Kaur, Navpreet; Ingle, Ekta

    2015-01-01

    To review advancements of fluoride in dentistry, a search of 21 electronic databases and World Wide Web was conducted. Relevant journals were hand searched and further information was requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Fluoride has become an important tool in preventive dentistry. Current research is focused on the development of strategies to improve fluoride efficacy. Fluoride therapy in the form of varnish, gel, mouth rinse, or toothpaste has been used extensively as a caries-preventive intervention for over three decades. The purpose of this review is to inform the reader about new research related to the use of fluoride for the prevention of dental caries. PMID:26539383

  8. The effect of water fluoride concentration on dental caries and fluorosis in five Iran provinces: A multi-center two-phase study

    PubMed Central

    Ramezani, Gholamhossein; Valaie, Nasser; Rakhshan, Vahid

    2015-01-01

    Background: Water fluoride level is unknown in many regions of Iran. Besides, only few non-controlled studies world-wide have assessed the effect of water fluoride on dental fluorosis and caries. We aimed to measure the fluoride level of 76 water supplies in 54 cities and evaluate the effect of fluoride on dental caries and fluorosis in a large multi-project study. Materials and Methods: In the first phase (cross-sectional), fluoride levels of 76 water tanks in 54 cities/villages in five provinces of Iran were randomly evaluated in five subprojects. In the second phase (retrospective cohort), 1127 middle school children (563 cohort and 564 control subjects) in the high and low ends of fluoride concentration in each subproject were visited. Their decayed, missing and filled teeth (DMFT) and fluorosis states were assessed. The data were analyzed using Chi-square, Mann-Whitney U and independent-samples t-test (α = 0.05). Results: Mean fluoride level was 0.298 ± 0.340 mg/L in 54 cities/villages. Only eight water tanks had fluoride levels within the normal range and only one was higher than normal and the rest (67 tanks) were all at low levels. Overall, a significant association was observed between fluoride level and fluorosis. However, this was not the case in all areas, as in 2 of 5 provinces, the effect of fluoride on fluorosis was not confirmed. In 4 of the 5 areas studied, there was a significant link between fluoride level and DMFT. Conclusion: Extremely low fluoride levels in Iran cities are an alarming finding and need attention. Higher fluoride is likely to reduce dental caries while increasing fluorosis. This finding was not confirmed in all the areas studied. PMID:25709672

  9. The effect of topical fluoride therapy on microleakage of tooth colored restorations

    PubMed Central

    Shabzendedar, Mahbobeh; Moosavi, Horieh; Kebriaee, Fatemeh; Daneshvar- Mozafari, Avideh

    2011-01-01

    Aim: The aim of this study was to evaluate the effect of pre and post fluoride therapy on the microleakage of composite resin and glass ionomer restorations. Materials and Methods: Class V cavities were prepared on the buccal surfaces of sixty extracted human third molars. Based on the restorative materials the samples were assigned into two essential groups of thirty and each of them divided into three subgroups regarding the mode of Acidulate Phosphate Fluoride (APF) gel usage. Fluoride therapy was applied pre and post restoration whether OptiBond Solo Plus as a total-etch adhesive system with Herculite XRV as a light cured composite resin or Fuji II LC glass ionomer as an restoration. Each essential group contained a control group without fluoride therapy. Thermo cycling was done, and then the rate of microleakage was evaluated by the fluid filtration method. Results: There were no significant differences by pre and post-treatment with APF on microleakage of composite resin restorations. A significant difference was found on microleakage of glass ionomer restorations based on different APF therapy. Conclusions: In contrast to composite resin restoration which had not influenced by fluoride therapy, after glass ionomer placement, the gel of fluoride led to significantly increase the microleakage of the restoration. PMID:22025837

  10. On the relationship between the rate of salivary flow and salivary fluoride clearance.

    PubMed

    Duckworth, Ralph M; Jones, S

    2015-01-01

    The amount of fluoride retained in the mouth following the application of dentifrices, mouthwashes, etc. may be important in determining their anticaries efficacy. In this study we investigated the relationship between the salivary flow rate and salivary fluoride clearance. Ten adults tested six mouthrinses, consisting of aqueous sodium fluoride solutions (0.013, 0.026 mol/l) with and without added sodium chloride (1.28 mol/l) or sucrose (0.44 mol/l), in a randomised order. Prior to each test, subjects swallowed, rinsed for 2 min with 2 ml water and then expectorated into a preweighed container to obtain a measure of initial saliva flow rate. Next, the procedure was repeated using one of the test rinses. Finally, samples of unstimulated whole saliva were collected for up to 3 h after each mouthrinse application and analysed for fluoride. Salivary fluoride concentrations were significantly lower after application of mouthrinses that contained either sucrose or NaCl, both of which compounds markedly enhanced salivary flow, than after the use of corresponding mouthrinses without any additive. Area under the salivary fluoride clearance curve (AUC) values were inversely correlated with salivary flow rate on an individual basis (p < 0.01). The observed behaviour could not be completely attributed to treatment dilution by saliva at the time of application. PMID:25634162

  11. Fluoride and potassium availability in a new dentifrice that treats hypersensitivity and controls tartar.

    PubMed

    Crawford, R J; Collins, M A; Clipper, D W; Prencipe, M

    1994-01-01

    The availability and stability of the active ingredients in a Sensitive/Tartar Control dentifrice have been evaluated in this study. The Sensitive/Tartar Control dentifrice contains 5% potassium nitrate as the anti-hypersensitivity agent, 0.243% sodium fluoride as the anti-caries agent, 2% tetrasodium pyrophosphate and 1.5% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer as the antitartar system. The availability of potassium and fluoride from this dentifrice was tested and found to be acceptable in both freshly prepared and aged samples. Fluoride and potassium availability were also tested at dilutions similar to in vivo brushing levels, and the ability of the Sensitive/Tartar Control dentifrice to provide fluoride to enamel and reduce enamel solubility was measured. In these tests the Sensitive/Tartar Control dentifrice performed similarly to commercial fluoride dentifrices. Potassium availability was equal to Crest Sensitivity Protection, a product shown to be clinically effective against tooth sensitivity; fluoride availability and activity was shown to be equal to Crest Tartar Control, a product with published clinical anti-caries effectiveness.

  12. Invitro Evaluation of Fluoride Release from Hydroxyapatite Reinforced Glass Ionomer with or without Protective Coating

    PubMed Central

    Nandlal, Bhojraj

    2016-01-01

    Introduction Glass Ionomer Cement (GIC) is well known for its fluoride releasing property but has its own drawbacks of poor mechanical properties, sensitivity to initial desiccation and moisture contamination. To overcome these, search led to the reinforcement of hydroxyapatite and application of surface coating agent but their effect on fluoride release is still not clear. Aim To evaluate and compare the release of fluoride from Hydroxyapatite Reinforced Glass Ionomer (HA-GIC) with and without protective coating. Materials and Methods Specimens were prepared as follows- Eight percent by weight conventional glass ionomer was replaced by hydroxyapatite powder (HA) and an indigenous product was prepared (HA-GIC). This powder was mixed with liquid of conventional GIC and allowed to set, then G coat plus coating agent was applied in surface coated group and light cured. Fluoride release of the sample was measured every 24 hrs for seven days and weekly from 7th to 21st day using combination ion selective electrode. Results Mean values clearly reveal a significant decrease in the fluoride release from day 1 to day 21 for both the groups. Results of repeated measure ANOVA revealed statistically significant difference between two groups (p <0.001). Conclusion Coating the hydroxyapatite reinforced glass ionomer will allow for slow and steady release of fluoride for a long period of time into oral environment. PMID:27190957

  13. Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

    NASA Astrophysics Data System (ADS)

    Jiang, Yun; Liu, Yu-qin; Ma, Hong-wen; Zhou, Wei-gong

    2016-04-01

    The use of a small amount of calcium fluoride as an additive greatly accelerated the reduction of magnesia during the preparation of magnesium from magnesia using the vacuum carbothermic reduction method. At 1573 K (1300 °C), the magnesia reaction rates of the samples with 1, 3, and 5 pct CaF2 were all approximately 26 pct, three times that of free CaF2, and they were arranged in order of the calcium fluoride weight percentages at 1673 K (1400 °C). The residues were analyzed using chemical analysis, XRD, SEM, EDS, and XRF. The possible acceleration mechanism was discussed. Calcium fluoride combined with magnesia and silicon dioxide to form a eutectic that melted as a channel to aid the solid-solid reaction between carbon and magnesia at approximately 1573 K (1300 °C). Calcium fluoride in the molten state offered free calcium ions and fluorine ions. Fluorine ions entered and distorted the magnesia crystal lattice. The structural strength and chemical stability of the magnesia crystal lattice decreased, which facilitated the magnesia reduction by carbon. Calcium ions were employed to generate the calcium and magnesium silicate. The easyly evaporating fluorides, including magnesium fluoride and silicon tetrafluoride, were regarded as the main reason for the loss of fluorine.

  14. The occurrence and geochemistry of fluoride in some natural waters of Kenya

    NASA Astrophysics Data System (ADS)

    Gaciri, S. J.; Davies, T. C.

    1993-03-01

    In recent years the acquisition of considerable additional data on the hydrogeochemical behaviour of fluoride in natural waters of Kenya has been made possible by extensive surface-water and groundwater sampling campaigns as well as by improvements in analytical techniques. Ultimately, the principal source of fluoride relates to emissions from volcanic activity associated with the East African Rift System. Through various intermediate steps, but also directly, fluoride passes into the natural water system and components of the food chain. Ingestion by man is mainly through drinking water and other beverages. River waters in Kenya generally have a fluoride concentration lower than the recommended level (1.3 ppm) for potable water, thus promoting susceptibility to dental caries. Groundwaters and lake waters show considerably higher fluoride contents, resulting in the widespread incidence of fluorosis in areas where groundwater is the major source of drinking water, and lake fish is a regular component of the diet. This paper presents a synthesis of the data so far obtained on the sources and distribution of fluoride in the hydrological system of Kenya, examines the extent of fluorine toxicity and puts forward recommendations to combat or minimise the problem.

  15. The investigation of kinetic and isotherm of fluoride adsorption onto functionalize pumice stone.

    PubMed

    Asgari, Ghorban; Roshani, Babak; Ghanizadeh, Ghader

    2012-05-30

    In this research work, pumice that is functionalized by the cationic surfactant, hexadecyltrimethyl ammonium (HDTMA), is used as an adsorbent for the removal of fluoride from drinking water. This work was carried out in two parts. The effects of HDTMA loading, pH (3-10), reaction time (5-60 min) and the adsorbent dosage (0.15-2.5 g L(-1)) were investigated on the removal of fluoride as a target contaminate from water through the design of different experimental sets in the first part. The results from this first part revealed that surfactant-modified pumice (SMP) exhibited the best performance at dose 0.5 g L(-1), pH 6, and it adsorbs over 96% of fluoride from a solution containing 10 mg L(-1) fluoride after 30 min of mixing time. The four linear forms of the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms model were applied to determine the best fit of equilibrium expressions. Apart from the regression coefficient (R(2)), four error functions were used to validate the isotherm and kinetics data. The experimental adsorption isotherm complies with Langmuir equation model type 1. The maximum amount of adsorption (Q(max)) was 41 mg g(-1). The kinetic studies indicated that the adsorption of fluoride best fitted with the pseudo-second-order kinetic type 1. Thermodynamic parameters evaluation of fluoride adsorption on SMP showed that the adsorption process under the selected conditions was spontaneous and endothermic. The suitability of SMP in defluoridation at field condition was investigated with natural groundwater samples collected from a nearby fluoride endemic area in the second part of this study. Based on this study's results, SMP was shown to be an affordable and a promising option for the removal of fluoride in drinking water.

  16. A preliminary investigation of lithogenic and anthropogenic influence over fluoride ion chemistry in the groundwater of the southern coastal city, Tamilnadu, India.

    PubMed

    Selvam, S

    2015-03-01

    A total of 72 groundwater samples were collected from open wells and boreholes during pre- and post-monsoon periods in Tuticorin. Samples were analyzed for physicochemical properties, major cations, and anions in the laboratory using the standard methods given by the American Public Health Association. The fluoride concentration was analyzed in the laboratory using Metrohm 861 advanced compact ion chromatography. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.3. The fluoride concentration ranges between 0.16 mg/l and 4.8 mg/l during pre-monsoon and 0.2-3.2 mg/l during post-monsoon. Alkaline pH, low calcium concentrations, high groundwater temperatures, and semiarid climatic conditions of the study area may cause elevated fluoride concentrations in groundwater, by increasing the solubility of fluoride-bearing formations (fluoride). Linear trend analysis on seasonal and annual basis clearly depicted that fluoride pollution in the study area is increasing significantly. Fluoride concentrations showed positive correlations with those of Na(+) and HCO3 (-) and negative correlations with Ca(2+) and Mg(2+). The alkaline waters were saturated with calcite in spite of the low Ca(2+) concentrations. Northwestern parts of the study area are inherently enriched with fluorides threatening several ecosystems. The saturation index indicates that dissolution and precipitation contribute fluoride dissolution along with mixing apart from anthropogenic activities. PMID:25666649

  17. A preliminary investigation of lithogenic and anthropogenic influence over fluoride ion chemistry in the groundwater of the southern coastal city, Tamilnadu, India.

    PubMed

    Selvam, S

    2015-03-01

    A total of 72 groundwater samples were collected from open wells and boreholes during pre- and post-monsoon periods in Tuticorin. Samples were analyzed for physicochemical properties, major cations, and anions in the laboratory using the standard methods given by the American Public Health Association. The fluoride concentration was analyzed in the laboratory using Metrohm 861 advanced compact ion chromatography. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.3. The fluoride concentration ranges between 0.16 mg/l and 4.8 mg/l during pre-monsoon and 0.2-3.2 mg/l during post-monsoon. Alkaline pH, low calcium concentrations, high groundwater temperatures, and semiarid climatic conditions of the study area may cause elevated fluoride concentrations in groundwater, by increasing the solubility of fluoride-bearing formations (fluoride). Linear trend analysis on seasonal and annual basis clearly depicted that fluoride pollution in the study area is increasing significantly. Fluoride concentrations showed positive correlations with those of Na(+) and HCO3 (-) and negative correlations with Ca(2+) and Mg(2+). The alkaline waters were saturated with calcite in spite of the low Ca(2+) concentrations. Northwestern parts of the study area are inherently enriched with fluorides threatening several ecosystems. The saturation index indicates that dissolution and precipitation contribute fluoride dissolution along with mixing apart from anthropogenic activities.

  18. A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas.

    PubMed

    Singh, Navneet; Verma, Kanika Gupta; Verma, Pradhuman; Sidhu, Gagandeep Kaur; Sachdeva, Suresh

    2014-01-01

    The study was undertaken to determine serum/urinary fluoride status and comparison of free T4, free T3 and thyroid stimulating hormone levels of 8 to 15 years old children with and without dental fluorosis living in an endemic and non-endemic fluorosis area. A sample group of 60 male and female school children, with or without dental fluorosis, consuming fluoride-contaminated water in endemic fluoride area of Udaipur district, Rajasthan were selected through a school dental fluorosis survey. The sample of 10 children of same age and socio-economic status residing in non endemic areas who did not have dental fluorosis form controls. Fluoride determination in drinking water, urine and blood was done with Ion 85 Ion Analyzer Radiometer with Hall et al. method. The thyroid gland functional test was done by Immonu Chemiluminiscence Micropartical Assay with Bayer Centaur Autoanalyzer. The significantly altered FT3, FT4 and TSH hormones level in both group1A and 1B school children were noted. The serum and urine fluoride levels were found to be increased in both the groups. A significant relationship of water fluoride to urine and serum fluoride concentration was seen. The serum fluoride concentration also had significant relationship with thyroid hormone (FT3/FT4) and TSH concentrations. The testing of drinking water and body fluids for fluoride content, along with FT3, FT4, and TSH in children with dental fluorosis is desirable for recognizing underlying thyroid derangements and its impact on fluorosis.

  19. Urinary fluoride excretion in children aged 3 to 5 years exposed to fluoridated salt at 60 to 90 mgF/Kg in two Venezuelan cities. A pilot study.

    PubMed

    Acevedo, Ana M; Febres-Cordero, Carolina; Feldman, Sonia; Arasme, Marlene A; Pedauga, Daniel F; González, Henry; Rojas-Sánchez, Fátima

    2007-01-01

    The aim of the present work was to obtain information on the total urinary fluoride concentration and excretion of Venezuelan children at the age of 3 to 5 years, as part of a program to monitor fluoride ingestion. A 24 hour urine sample was collected from each of 63 children, between 3 and 5 years of age and analyzed for (i) total urinary volume (ml), (ii) urinary flow rate (ml/h), (iii) fluoride concentration (ppm) and (iv)fluoride excretion rate (microg/h). The group comprised 32 boys and 31 girls who resided in two different communities, 32 in Caracas, DC and 31 in San Juan de los Morros, Guarico state. Fluoride analyses were done with an ion-specific electrode. Age and gender did not affect total urine volume, urinary flow rate, or urinary fluoride concentration and excretion rate. The children from San Juan de los Morros had a significantly higher total urinary volume (426.45 +/- 36.31 ml) and flow rate (17.09 +/- 1.57ml/h) than children from Caracas (297.06 +/- 23.59 ml and 12.40 +/- 0.98, respectively) (p=0.0039). Significant differences were also observed when the urinary fluoride excretion rate of the two communities was compared. Mean urinary fluoride concentrations did not differ significantly (p < 0.05) between the two communities. These values were 0.67 +/- 0.40, 0.57 +/- 0.34, 0.76 +/- 0.27 ppmF in the 3, 4 and 5 year-old children of Caracas and 0.69 +/- 0.33, 0.65 +/- 0.20, 0.63 +/- 0.36 mgF in San Juan de los Morros children. The results showed low urinary fluoride concentration and excretion, indicating that children residing in the evaluated communities are receiving fluoride below the recommended optimal range.

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

    PubMed

    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.

  1. Potable groundwater quality in some villages of Haryana, India: focus on fluoride.

    PubMed

    Bishnoi, Mukul; Arora, Shalu

    2007-04-01

    The fluoride concentration in ground water was determined in ten villages of Rohtak district of Haryana state (India). The fluoride concentration in the underground water of these villages varied from 0.034-2.09 mg/l. Various other water quality parameters, viz., pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride and sulfate were also measured. A systematic calculation of correlation coefficients among different physicochemical parameters indicated considerable variations among the analyzed samples with respect to their chemical composition. Majority of the samples do not comply with Indian as well as WHO standards for most of the water quality parameters measured. Overall water quality was found unsatisfactory for drinking purposes. Fluoride content was higher than permissible limit in 50% samples.

  2. 21 CFR 872.6870 - Disposable fluoride tray.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Disposable fluoride tray. 872.6870 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6870 Disposable fluoride tray. (a) Identification. A disposable fluoride tray is a device made of styrofoam intended to apply fluoride topically...

  3. 21 CFR 872.6870 - Disposable fluoride tray.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Disposable fluoride tray. 872.6870 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6870 Disposable fluoride tray. (a) Identification. A disposable fluoride tray is a device made of styrofoam intended to apply fluoride topically...

  4. Fluoride Programs in the School Setting: Preventive Dental Health.

    ERIC Educational Resources Information Center

    Rebich, Theodore, Jr.; And Others

    1982-01-01

    Two types of school-based programs that increase students' use of fluoride for preventive dental health are described. In fluoride mouthrinse programs, teachers give their students a fluoride solution once a week in a paper cup. In areas where the level of fluoride in the water supply is insufficient, the flouride tablet program is used. (JN)

  5. Fluoridation and Defluoridation. Training Module 2.230.2.77.

    ERIC Educational Resources Information Center

    McMullen, L. D.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with fluoridation and fluoride feeding equipment. Enclosed are objectives, an instructor guide, student handouts and transparency masters. The module considers the principles and purposes of fluoridation, methods of feeding fluoride,…

  6. Comparison of storage stability of odorous VOCs in polyester aluminum and polyvinyl fluoride tedlar bags

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole air sampling using containers such as flexible bags or rigid canisters is commonly used to collect samples of volatile organic compounds (VOC) in air. The objective of this study was to compare the stability of polyester aluminum (PEA) and polyvinyl fluoride (PVF, brand name Tedlar®) bags for ...

  7. Recovery of agricultural odors and odorous compounds from polyvinyl fluoride film bags

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human ...

  8. Increased ash contents and estimation of dissolution from chemical changes due to in-vitro fluoride treatments.

    PubMed

    Kotha, S P; DePaula, C A; Koike, K; Pan, Y; Ohno, M; Abjornson, C; Rangarajan, S; Guzelsu, N

    2002-01-01

    The in-vitro fluoride treatment technique has been introduced to investigate the composite behavior of bone tissue. Bone tissue with different mechanical properties can be obtained by varying the concentration, pH and immersion time in fluoride ion solutions. The chemical and physical changes in intact pieces of bone treated in-vitro with different concentrations of fluoride ions are studied. The amount of bone mineral that does not contribute to the mechanical behavior of bone tissue is estimated from the dissolution occurring in the fluoride treated bones. Cortical bones from 18-month-old steers were treated in-vitro with 0.145, 0.5 and 2.0 M sodium fluoride (NaF) solutions for three days. The dissolved bone mineral precipitates as calcium fluoride-like (CaF2/P with some phosphate [P] ions) and fluorapatite(FAp)/fluorhydroxyapatite(FHAp)-like materials within the bone tissue. The dissolution estimated from the presence of the precipitated fluoride phases is 5.6, 11.7, and 13.1% of the initial bone mineral content for the 0.145 M, 0.5 M, and 2.0 M NaF treatments respectively. Estimates of dissolution based on the measurements of phosphate and carbonate ions are lower and higher respectively when compared to the fluoride ion measurements. The wet and dry densities decreased slightly due to dissolution and re-precipitation while the ash content (ratio of the ash weight to dry weight) increased a small amount with increasing concentration of fluoride ion treatments. The increased ash content was due to the excess loss of water in the fluoride treated bones as compare to controls (untreated bone samples) during the drying process. The increased removal of water during the drying process may explain the increased ash contents in some in-vivo treatments.

  9. Measuring Hydrogen Concentrations in Metals

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1985-01-01

    Commercial corrosion-measurement system adapted to electrochemical determination of hydrogen concentrations in metals. New technique based on diffusion of hydrogen through foil specimen of metal. In sample holder, hydrogen produced on one side of foil, either by corrosion reaction or by cathodic current. Hydrogen diffused through foil removed on other side by constant anode potential, which leads to oxidation of hydrogen to water. Anode current is measure of concentration of hydrogen diffusing through foil. System used to study hydrogen uptake, hydrogen elimination by baking, effect of heat treatment, and effect of electroplating on high-strength steels.

  10. Drinking Water Fluoride Levels for a City in Northern Mexico (Durango) Determined Using a Direct Electrochemical Method and Their Potential Effects on Oral Health

    PubMed Central

    Molina Frechero, Nelly; Sánchez Pérez, Leonor; Castañeda Castaneira, Enrique; Oropeza Oropeza, Anastasio; Gaona, Enrique; Salas Pacheco, José; Bologna Molina, Ronell

    2013-01-01

    Fluoride is ingested primarily through consuming drinking water. When drinking water contains fluoride concentrations >0.7 parts per million (ppm), consuming such water can be toxic to the human body; this toxicity is called “fluorosis.” Therefore, it is critical to determine the fluoride concentrations in drinking water. The objective of this study was to determine the fluoride concentration in the drinking water of the city of Durango. The wells that supply the drinking water distribution system for the city of Durango were studied. One hundred eighty-nine (189) water samples were analyzed, and the fluoride concentration in each sample was quantified as established by the law NMX-AA-077-SCFI-2001. The fluoride concentrations in such samples varied between 2.22 and 7.23 ppm with a 4.313 ± 1.318 ppm mean concentration. The highest values were observed in the northern area of the city, with a 5.001 ± 2.669 ppm mean value. The samples produced values that exceeded the national standard for fluoride in drinking water. Chronic exposure to fluoride at such concentrations produces harmful health effects, the first sign of which is dental fluorosis. Therefore, it is essential that the government authorities implement water defluoridation programs and take preventative measures to reduce the ingestion of this toxic halogen. PMID:24348140

  11. Drinking water fluoride levels for a city in northern Mexico (durango) determined using a direct electrochemical method and their potential effects on oral health.

    PubMed

    Molina Frechero, Nelly; Sánchez Pérez, Leonor; Castañeda Castaneira, Enrique; Oropeza Oropeza, Anastasio; Gaona, Enrique; Salas Pacheco, José; Bologna Molina, Ronell

    2013-01-01

    Fluoride is ingested primarily through consuming drinking water. When drinking water contains fluoride concentrations>0.7 parts per million (ppm), consuming such water can be toxic to the human body; this toxicity is called "fluorosis." Therefore, it is critical to determine the fluoride concentrations in drinking water. The objective of this study was to determine the fluoride concentration in the drinking water of the city of Durango. The wells that supply the drinking water distribution system for the city of Durango were studied. One hundred eighty-nine (189) water samples were analyzed, and the fluoride concentration in each sample was quantified as established by the law NMX-AA-077-SCFI-2001. The fluoride concentrations in such samples varied between 2.22 and 7.23 ppm with a 4.313±1.318 ppm mean concentration. The highest values were observed in the northern area of the city, with a 5.001±2.669 ppm mean value. The samples produced values that exceeded the national standard for fluoride in drinking water. Chronic exposure to fluoride at such concentrations produces harmful health effects, the first sign of which is dental fluorosis. Therefore, it is essential that the government authorities implement water defluoridation programs and take preventative measures to reduce the ingestion of this toxic halogen.

  12. Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro.

    PubMed

    Delbem, Alberto Carlos Botazzo; Souza, José Antonio Santos; Zaze, Ana Carolina Soares Fraga; Takeshita, Eliana Mitsue; Sassaki, Kikue Takebayashi; Moraes, João Carlos Silos

    2014-01-01

    The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite. PMID:25590192

  13. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    PubMed Central

    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

  14. Review of fluoride removal from drinking water.

    PubMed

    Mohapatra, M; Anand, S; Mishra, B K; Giles, Dion E; Singh, P

    2009-10-01

    Fluoride in drinking water has a profound effect on teeth and bones. Up to a small level (1-1.5mg/L) this strengthens the enamel. Concentrations in the range of 1.5-4 mg/L result in dental fluorosis whereas with prolonged exposure at still higher fluoride concentrations (4-10mg/L) dental fluorosis progresses to skeletal fluorosis. High fluoride concentrations in groundwater, up to more than 30 mg/L, occur widely, in many parts of the world. This review article is aimed at providing precise information on efforts made by various researchers in the field of fluoride removal for drinking water. The fluoride removal has been broadly divided in two sections dealing with membrane and adsorption techniques. Under the membrane techniques reverse osmosis, nanofiltration, dialysis and electro-dialysis have been discussed. Adsorption, which is a conventional technique, deals with adsorbents such as: alumina/aluminium based materials, clays and soils, calcium based minerals, synthetic compounds and carbon based materials. Studies on fluoride removal from aqueous solutions using various reversed zeolites, modified zeolites and ion exchange resins based on cross-linked polystyrene are reviewed. During the last few years, layered double oxides have been of interest as adsorbents for fluoride removal. Such recent developments have been briefly discussed.

  15. Current status of fluoride volatility method development

    SciTech Connect

    Uhlir, J.; Marecek, M.; Skarohlid, J.

    2013-07-01

    The Fluoride Volatility Method is based on a separation process, which comes out from the specific property of uranium, neptunium and plutonium to form volatile hexafluorides whereas most of fission products (mainly lanthanides) and higher transplutonium elements (americium, curium) present in irradiated fuel form nonvolatile tri-fluorides. Fluoride Volatility Method itself is based on direct fluorination of the spent fuel, but before the fluorination step, the removal of cladding material and subsequent transformation of the fuel into a powdered form with a suitable grain size have to be done. The fluorination is made with fluorine gas in a flame fluorination reactor, where the volatile fluorides (mostly UF{sub 6}) are separated from the non-volatile ones (trivalent minor actinides and majority of fission products). The subsequent operations necessary for partitioning of volatile fluorides are the condensation and evaporation of volatile fluorides, the thermal decomposition of PuF{sub 6} and the finally distillation and sorption used for the purification of uranium product. The Fluoride Volatility Method is considered to be a promising advanced pyrochemical reprocessing technology, which can mainly be used for the reprocessing of oxide spent fuels coming from future GEN IV fast reactors.

  16. [Fluoride-induced nephrotoxicity: factor fiction?].

    PubMed

    Nuscheler, M; Conzen, P; Schwender, D; Peter, K

    1996-02-01

    In the 1960s, the widespread use of the inhalational anaesthetic methoxyflurane was associated with a significant occurrence of postoperative renal dysfunction. This was attributed to hepatic biotransformation of methoxyflurane and subsequent release of inorganic fluoride ions into the circulation. Based upon the clinical experience with methoxyflurane, serum fluoride concentrations exceeding 50 mumol/l were considered to be nephrotoxic. Without further reevaluation, this 50 mumol/l threshold was subsequently applied to other fluorinated anaesthetics as well. Enflurane and even isoflurane may, when used during prolonged operations, also yield anorganic fluoride levels in excess of 50 mumol/l. Nevertheless, no cases of renal dysfunction attributable to prolonged use of these anesthetics have been reported. About 4% of the new inhalational anaesthetic sevoflurane is metabolized, and fluoride concentrations exceeding those after enflurane are frequently measured. Numerous studies have examined the nephrotoxic potential of sevoflurane degradation products. However, fluoride-related toxicity has been observed neither in animal nor in clinical studies, including prolonged administration and patients with pre-existing renal disease. New insights into the intrarenal metabolisation of volatile anaesthetics may well explain the absence of nephrotoxicity after sevoflurane. The threshold for fluoride nephrotoxicity of 50 mumol/l, still given in many medical text-books, can no longer be applied as an indicator of nephrotoxicity after isoflurane, enflurane or sevoflurane. Therefore, the elevated serum fluoride concentrations consistently recorded following anaesthesia with sevoflurane are devoid of clinical significance. PMID:8775101

  17. Fluoride Plus Functionalized β-TCP

    PubMed Central

    Karlinsey, R.L.; Pfarrer, A.M.

    2012-01-01

    With more than 50 years of clinical success, fluoride serves as the gold standard agent for preventing tooth decay. In particular, the action of fluoride facilitates saliva-driven remineralization of demineralized enamel and alters solubility beneficially. Still, tooth decay remains problematic, and one way to address it may be through the development of new mineralizing agents. Laboratory and clinical studies have demonstrated that the combination of fluoride and functionalized β-tricalcium phosphate (fTCP) produces stronger, more acid-resistant mineral relative to fluoride, native β-TCP, or fTCP alone. In contrast to other calcium-based approaches that seem to rely on high levels of calcium and phosphate to drive remineralization, fTCP is a low-dose system designed to fit within existing topical fluoride preparations. The functionalization of β-TCP with organic and/or inorganic molecules provides a barrier that prevents premature fluoride-calcium interactions and aids in mineralization when applied via common preparations and procedures. While additional clinical studies are warranted, supplementing with fTCP to enhance fluoride-based nucleation activity, with subsequent remineralization driven by dietary and salivary calcium and phosphate, appears to be a promising approach. PMID:22899679

  18. Hydrogen fluoride capture by imidazolium acetate ionic liquid

    NASA Astrophysics Data System (ADS)

    Chaban, Vitaly

    2015-04-01

    Extraction of hydrofluoric acid (HF) from oils is a drastically important problem in petroleum industry, since HF causes quick corrosion of pipe lines and brings severe health problems to humanity. Some ionic liquids (ILs) constitute promising scavenger agents thanks to strong binding to polar compounds and tunability. PM7-MD simulations and hybrid density functional theory are employed here to consider HF capture ability of ILs. Discussing the effects and impacts of the cation and the anion separately and together, we evaluate performance of imidazolium acetate and outline systematic search guidelines for efficient adsorption and extraction of HF.

  19. An enhanced hydrogen adsorption enthalpy for fluoride intercalated graphite compounds.

    PubMed

    Cheng, Hansong; Sha, Xianwei; Chen, Liang; Cooper, Alan C; Foo, Maw-Lin; Lau, Garret C; Bailey, Wade H; Pez, Guido P

    2009-12-16

    We present a combined theoretical and experimental study on H(2) physisorption in partially fluorinated graphite. This material, first predicted computationally using ab initio molecular dynamics simulation and subsequently synthesized and characterized experimentally, represents a novel class of "acceptor type" graphite intercalated compounds that exhibit significantly higher isosteric heat of adsorption for H(2) at near ambient temperatures than previously demonstrated for commonly available porous carbon-based materials. The unusually strong interaction arises from the semi-ionic nature of the C-F bonds. Although a high H(2) storage capacity (>4 wt %) at room temperature is predicted not to be feasible due to the low heat of adsorption, enhanced storage properties can be envisaged by doping the graphitic host with appropriate species to promote higher levels of charge transfer from graphene to F(-) anions. PMID:19928879

  20. Low temperature cold trapping of uranium hexafluoride containing hydrogen fluoride

    SciTech Connect

    Hobbs, W.E.; Barber, E.J.; Jones, C.G.

    1990-10-01

    The use of a freezer-sublimer system operating at low desublimation pressures to replace 10-in. nuclearly safe cold traps for low assay (<5% U-235) uranium hexafluoride (UF{sub 6}) would significantly simplify operations and is economically attractive provided the nuclear safety of the system can be assured. A major requirement of such assurance is the availability of conditions guaranteeing that the nuclear safety design criterion, which requires that the H/U atomic ratio in the condensate in the freezer-sublimer always be less than 0.33 for assays up to 5%, will never be violated. A general vapor pressure equation giving the vapor pressure of HF-UF{sub 6} solutions as a function of temperature and mole fraction UF{sub 6} has been developed. The precision of the data at the 95% confidence level is {plus minus}0.1 torr at temperatures between {minus}100{degree}F and {minus}121{degree}F. The calculated vapor pressure of pure HF is 4.6 torr at {minus}100{degree}F and 3.1 torr at {minus}108{degree}F. Theoretical considerations suggest that the true value will be slightly lower. In experimental studies of the cold trapping operation at {minus}108{degree}F and at a trap pressure of 2.2 torr, only 7.3% of the HF entering the trap was retained in the trap. At a trap pressure of 4.6 torr, over 80% of the HF entering the trap was retained. The data obtained in this study confirms that the physical chemistry of the HF-UF{sub 6} system previously developed accurately describes the behavior of the system and that so long as the pressure in the trap is maintained below the vapor pressure of pure HF at the trap temperatures, there is no way that sufficient HF can be trapped to give an H/U ratio of 0.33 regardless of the HF/UF{sub 6} ratio in the feed to the trap. 5 refs., 4 tabs.

  1. The effects of airborne fluorides on oral conditions in Morocco

    SciTech Connect

    Haikel, Y.; Cahen, P.M.; Turlot, J.C.; Frank, R.M. )

    1989-08-01

    The purpose of this study was to determine the prevalence and severity of dental caries and dental fluorosis, as well as various other oral conditions, in 2378 subjects (ages seven to 60) living in the fluoridated area of Khouribga and the non-fluoridated area of Beni Mellal, Morocco. The community index of dental fluorosis (CFI) ranged from 1.99 to 2.80 in the high-fluoride area: Over 90% of the population was affected, and more than one-third of the subjects showed moderate dental fluorosis. However, in Beni Mellal, more than 96% of the dentate subjects examined were free of dental fluorosis, and the CFI of 0.02 was considered not significant. Significant differences were observed between the two areas with respect to caries prevalence. DMFT and DMFS indices were markedly lower in the fluorosis area of Khouribga. The oral conditions of subjects appeared to be better in Khouribga, where the gingival and calculus indices were significantly lower than in Beni Mellal. The analyses of covariance showed no significant differences in plaque accumulation (PI) between the Khouribga and Beni Mellal samples. However, a close statistical correlation was found between PI and GI in Beni Mellal and Khouribga.

  2. Fluoride contamination of aquifers in the southeast subhumid pampa, Argentina.

    PubMed

    Paoloni, J D; Fiorentino, C E; Sequeira, M E

    2003-10-01

    A diagnostic survey was carried out of the groundwater in the southeast subhumid pampa of Argentina in order to determine the presence, spatial distribution, and concentration of fluoride. The area studied extends along the southeastern border of the pampa plains between latitude 38 degrees 18' and 38 degrees 58' S and longitude 60 degrees 43' and 61 degrees 43' W, covering an irregular surface area of approximately 6000 km2. The region has a large rural and suburban population that relies on this groundwater as its principal source of water for human consumption and for use in agricultural and livestock production. The variation in fluoride content in the groundwater is illustrated on maps of the area, showing that the whole region is affected by this ion contaminant. In 97.1% of the samples fluoride values exceeded the limits recommended by the Argentine Food Code for human consumption and indicated that the use of the water in livestock should be restricted. The quality of the water for irrigation purposes also was seriously affected. Critically affected zones were identified with a view to implementing public health measures to protect against this highly contaminated resource.

  3. Quantification of fluoride in food by microwave acid digestion and fluoride ion-selective electrode.

    PubMed

    Rocha, René A; Rojas, Dayana; Clemente, María Jesús; Ruiz, Antonio; Devesa, Vicenta; Vélez, Dinoraz

    2013-11-13

    To quantify fluoride in food it is necessary to extract the fluoride from the matrix. Dry ashing (alkali fusion) and facilitated diffusion are the methods most commonly used, but their application requires lengthy treatments. The present study proposes the use of a microwave oven and 7 mol/L nitric acid for simple, rapid digestion of foods for fluoride analysis. The analyte is subsequently quantified by fluoride ion-selective electrode. The various steps of the method were optimized and an in-house validation was performed. The limit of quantification (0.130 mg/kg), trueness (92%), recovery (84-101%), and precision (1-8%) were determined. These analytical characteristics are satisfactory and show the suitability of the method for analysis of fluoride in foods of various kinds. The method's ease of application and the use of equipment normally found in food analysis laboratories may help to further increase research on fluoride concentrations in foods consumed by the population.

  4. PROCESS FOR TREATING VOLATILE METAL FLUORIDES

    DOEpatents

    Rudge, A.J.; Lowe, A.J.

    1957-10-01

    This patent relates to the purification of uranium hexafluoride, made by reacting the metal or its tetrafluoride with fluorine, from the frequently contained traces of hydrofluoric acid. According to the present process, UF/sub 6/ containing as an impurity a small amount of hydrofluoric acid, is treated to remove such impurity by contact with an anhydrous alkali metal fluoride such as sodium fluoride. In this way a non-volatile complex containing hydrofluoric acid and the alkali metal fluoride is formed, and the volatile UF /sub 6/ may then be removed by distillation.

  5. The effect of fluoride impregnated dental floss on enamel fluoride uptake in vitro and streptococcus mutans colonization in vivo.

    PubMed

    Chaet, R; Wei, S H

    1977-01-01

    The conclusions reached from this investigation can be summarized as follows: Fluoride can be incorporated into unwaxed dental floss. Placement of the fluoride impregnated dental floss in acid-buffer solution results in the release of most of the fluoride in the floss. Interproximal surfaces of teeth treated in vitro with fluoride impregnated dental floss acquired significantly (approximately three fold) more enamel fluoride than those treated with plain dental floss. The number of in vivo interproximal areas harboring Streptococcus mutans was reduced significantly after treatment with fluoride impregnated dental floss. Further studies should be done to establish the biological, physiochemical, manufacturing, and practical aspects of fluoride impregnated dental floss.

  6. The effects of fluoridated water on bone strength.

    PubMed

    Turner, C H; Akhter, M P; Heaney, R P

    1992-07-01

    Fluoride from fluoridated water accumulates not only in the enamel of teeth but also in the skeleton. The effects of fluoridated water on the skeleton are not well understood, yet there is some evidence that fluoridated water consumption increases the incidence of fractures. In the present study, femoral bending strength was measured in rats on fluoride intakes that ranged from low levels to levels well above natural high fluoride drinking water. Bone strength followed a biphasic relationship with bone fluoride content. Fluoride had a positive effect on bone strength for lower fluoride intakes and a negative influence on bone strength for higher fluoride intakes. The vertebral fluoride content at which femoral strength was maximum was between 1,100 and 1,500 ppm. The increase in femoral strength at this fluoride level was not accompanied by an increase in femoral bone density. The optimal fluoride content is within the range of bone fluoride contents found in persons living in regions with fluoridated water (1 ppm) for greater than 10 years.

  7. REDUCTION OF FLUORIDE TO METAL

    DOEpatents

    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.

  8. Factors affecting fluoride and natural organic matter (NOM) removal from natural waters in Tanzania by nanofiltration/reverse osmosis.

    PubMed

    Shen, Junjie; Schäfer, Andrea I

    2015-09-15

    This study examined the feasibility of nanofiltration (NF) and reverse osmosis (RO) in treating challenging natural tropical waters containing high fluoride and natural organic matter (NOM). A total of 166 water samples were collected from 120 sources within northern Tanzania over a period of 16 months. Chemical analysis showed that 81% of the samples have fluoride levels exceeding the WHO drinking guideline of 1.5mg/L. The highest fluoride levels were detected in waters characterized by high ionic strength, high inorganic carbon and on some occasions high total organic carbon (TOC) concentrations. Bench-scale experiments with 22 representative waters (selected based on fluoride concentration, salinity, origin and in some instances organic matter) and 6 NF/RO membranes revealed that ionic strength and recovery affected fluoride retention and permeate flux. This is predominantly due to osmotic pressure and hence the variation of diffusion/convection contributes to fluoride transport. Different membranes had distinct fluoride removal capacities, showing different raw water concentration treatability limits regarding the WHO guideline compliance. BW30, BW30-LE and NF90 membranes had a feed concentration limit of 30-40 mg/L at 50% recovery. NOM retention was independent of water matrices but is governed predominantly by size exclusion. NOM was observed to have a positive impact on fluoride removal. Several mechanisms could contribute but further studies are required before a conclusion could be drawn. In summary, NF/RO membranes were proved to remove both fluoride and NOM reliably even from the most challenging Tanzanian waters, increasing the available drinking water sources.

  9. Factors affecting fluoride and natural organic matter (NOM) removal from natural waters in Tanzania by nanofiltration/reverse osmosis.

    PubMed

    Shen, Junjie; Schäfer, Andrea I

    2015-09-15

    This study examined the feasibility of nanofiltration (NF) and reverse osmosis (RO) in treating challenging natural tropical waters containing high fluoride and natural organic matter (NOM). A total of 166 water samples were collected from 120 sources within northern Tanzania over a period of 16 months. Chemical analysis showed that 81% of the samples have fluoride levels exceeding the WHO drinking guideline of 1.5mg/L. The highest fluoride levels were detected in waters characterized by high ionic strength, high inorganic carbon and on some occasions high total organic carbon (TOC) concentrations. Bench-scale experiments with 22 representative waters (selected based on fluoride concentration, salinity, origin and in some instances organic matter) and 6 NF/RO membranes revealed that ionic strength and recovery affected fluoride retention and permeate flux. This is predominantly due to osmotic pressure and hence the variation of diffusion/convection contributes to fluoride transport. Different membranes had distinct fluoride removal capacities, showing different raw water concentration treatability limits regarding the WHO guideline compliance. BW30, BW30-LE and NF90 membranes had a feed concentration limit of 30-40 mg/L at 50% recovery. NOM retention was independent of water matrices but is governed predominantly by size exclusion. NOM was observed to have a positive impact on fluoride removal. Several mechanisms could contribute but further studies are required before a conclusion could be drawn. In summary, NF/RO membranes were proved to remove both fluoride and NOM reliably even from the most challenging Tanzanian waters, increasing the available drinking water sources. PMID:26005995

  10. Daily Fluoride Intake from Iranian Green Tea: Evaluation of Various Flavorings on Fluoride Release.

    PubMed

    Maleki, Afshin; Daraei, Hiua; Mohammadi, Elham; Zandi, Shiva; Teymouri, Pari; Mahvi, Amir Hossien; Gharibi, Fardin

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

  11. Effects of treatment with sodium fluoride and subsequent starvation on fluoride content of earthworms

    SciTech Connect

    Walton, K.C.

    1987-01-01

    The two experiments described here originated during a long-term investigation into the occurrence and movement of pollutant fluoride in a terrestrial ecosystem. Moles (Talpa europaea) whose diet consist largely of various species of earthworm Lumbricidae, are one of the species under investigation. Bone fluoride in moles was found to be higher, on average, than in foxes or small rodents. Moles probably acquire fluoride from their earthworm diet. Earthworms do not have any readily identifiable tissue in which to store large amounts of fluoride but, for their size, they have a considerable amount of soil in their gut, up oto 20% of their dry weight. Preliminary measurements of fluoride in whole earthworms suggested that observed levels could probably be accounted for by fluoride bound in the mineral part of contained soil and released during preparatory ashing. Two experiments to investigate this situation are described; here their aims were: to expose earthworms kept in soil to different concentrations of sodium fluoride; to measure resulting fluoride in earthworms when soil was removed from their gut by starvation for varying periods of time; and to compare amounts of fluoride in whole starved earthworms with those in starved earthworms from which remaining soil had also been physically removed by dissection and washing.

  12. Daily Fluoride Intake from Iranian Green Tea: Evaluation of Various Flavorings on Fluoride Release

    PubMed Central

    Maleki, Afshin; Daraei, Hiua; Mohammadi, Elham; Zandi, Shiva; Teymouri, Pari; Mahvi, Amir Hossien; Gharibi, Fardin

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

  13. Daily Fluoride Intake from Iranian Green Tea: Evaluation of Various Flavorings on Fluoride Release.

    PubMed

    Maleki, Afshin; Daraei, Hiua; Mohammadi, Elham; Zandi, Shiva; Teymouri, Pari; Mahvi, Amir Hossien; Gharibi, Fardin

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers.

  14. Inhaled magnesium fluoride reverse bronchospasma.

    PubMed

    Gandia, Fedoua; Rouatbi, Sonia; Latiri, Imed; Guénard, Hervé; Tabka, Zouhair

    2010-01-01

    Asthma is a global health problem. Asthma attacks are becoming more severe and more resistant to usual treatment by beta(2) agonists nebulisation. The search for a new product that could reduce the morbidity of asthmatic disease seems necessary. The objective of this study was to compare the effectiveness of inhaled magnesium fluoride (MgF(2)) with that of magnesium sulphate (MgSO(4)) 15% alone and sodium fluoride (NaF) 0.5 M alone in rats pre-contracted by methacholine (MeCh). Fifty six adult male Wistar rats of medium weight 259 +/- 15 g were divided randomly into five groups. They inhaled respectively: MeCh, MgF(2) + NaCl 0.9%, MgF(2) + acetic acid, MgSO(4) 15% single and NaF (0.5 M) single. Airway resistances were measured after each dose of MeCh by pneumomultitest equipment. Results indicated that (1) MgF(2) + NaCl 0.9%, MgF(2) + acetic acid and MgSO(4) reversed significantly the methacholine-induced bronchial constriction in rats and had a bronchodilating effect at the moment of its administration (2) MgF(2) + acetic acid led to a greater decrease (P<0.05) of bronchial resistances when compared to that obtained from MgF(2) + NaCl 0.9%, NaF exclusively and MgSO(4) alone (3) inhaled NaF alone led to a significant bronchorelaxing effect (P<0.05) that starts at the sixth dose of MeCh (17 mg/L). As a matter of fact, MgF(2) dissolved in acetic acid and delivered in aerosol form reduces significantly bronchial spasm. In conclusion, MgF(2) can be used as a bronchodilator for diseases with bronchospasma such as asthma and chronic obstructive pulmonary disease (COPD).

  15. [Fluoride contents of rat molars following the administration of amine-fluoride-containing caries preventives (author's transl)].

    PubMed

    Novikov, L L; Treide, A; Kolesnik, A G; Novikova, N V; Jacobi, J

    1979-01-01

    Experiments on fifty Wistar rats were conducted with the object of studying the incorporation of fluoride into the enamel of molars subsequent to the administration of amine-fluoride-containing caries preventives. - Use of two toothpastes with low fluoride contents of 0.125% and 0.18% F, respectively, and two higher-fluoride (1% F) solutions resulted in a marked increase in the concentration of fluoride in the superficial layers of dental enamel.

  16. On the structure and morphology of poly (vinylidene fluoride) nanoscrolls

    NASA Astrophysics Data System (ADS)

    Burks, Gabriel; Gleeson, Sarah; Mei, Shan; Qi, Hao; Li, Christopher

    Beyond its widely popular piezoelectric effect and β-phase molecular conformation, poly (vinylidene fluoride) PVDF also offers great intrigue as it relates to understanding its intrinsic crystallization behavior and morphological preference. It has been suggested that the γ-phase of PVDF adopts a highly regular scrolling lamellar habit which can be attributed to small differences in the folding volume of atomic level hydrogen and fluorine atoms resulting in the evolution of highly curved polymer lamellae. To date this scrolled morphology of γ-phase PVDF has been witnessed via high temperature melt crystallization of crystalline thin films and via severe chemical etching of PVDF bulk films. Here we show the first growth of free-standing γ-phase PVDF scrolls via the solution crystallization technique. Differential scanning calorimetry (DSC), X-Ray Diffraction (XRD), Fourier Transformed-Infrared Spectroscopy (FT-IR), and Atomic Force Microscopy (AFM) have been used to both characterize and to further understand the fundamental preferred crystalline habit of the γ-phase of poly (vinylidene fluoride).

  17. Determination of fluoride using ion-selective electrodes in the presence of aluminum.

    PubMed

    Borjigin, Siqingaowa; Ashimura, Yuuta; Yoshioka, Toshiaki; Mizoguchi, Tadaaki

    2009-12-01

    We describe a method for determining fluoride with ion-selective electrodes (ISEs). Tartrate and Tris-based total ionic strength adjustment buffers (TISABs) were found to lower the interference from aluminum to a greater extent than conventional citrate-based TISABs. We adopted a solid TISAB addition method that is simple to perform, and can be carried out without lowering the level of fluoride. The apparent recovery of fluoride was 95% or higher, even at 500 mg L(-1) of Al3+ when a tartrate and Tris-based TISAB was used. Interferences from common ions were not observed at 100 mg L(-1) levels. We determined the fluoride content in solid silicate samples with ISEs without preliminary steam distillation after alkali fusion processing. Adding a solid TISAB mixture consisting of tartaric acid, sodium tartrate, and Tris, however, eliminated any interference from high levels of aluminum and sodium and potassium carbonates. The proposed analytical method was also applied to the determination of fluoride in geochemical reference samples. PMID:20009331

  18. Validation of an ion selective electrode system for the analysis of serum fluoride ion.

    PubMed

    Duly, E B; Luney, S R; Trinick, T R; Murray, J M; Comer, J E

    1995-01-01

    A high impedance unit was developed for use with a fluoride/pH electrode system for the measurement of serum fluoride. The linearity, accuracy, precision and detection limit of the system is reported. At a pH of 1.55, the system was linear over a range of serum fluoride concentrations up to 100 mumol l(-1), with a lower limit of detection of 0.3 mumol l(-1). Recoveries at this pH were 94-105% in the range 2.6-100 mumol l(-1). Within-run CVs ranged from 4.2% at a level of 2.3 mumol l(-1) to 1.2% at a level of 55.7 mumol l(-1), while day-to-day CVs ranged from 12.8% at a level of 2.2 mumol l(-1) to 4.6% at a level of 51.7 mumol l(-1). The system demonstrated a rapid response time and has the potential for a smaller sample size requirement with alternative electrode shape. Continued development of this unit into an automated fluoride ion selective electrode system is recommended, since the measurement of serial serum fluoride samples is of greatest importance in assessing the impact of new anaesthetic agents on renal function. PMID:18925049

  19. Shock Induced Birefringence in Lithium Fluoride

    SciTech Connect

    Holmes, N C

    2001-06-01

    We have used an ellipsometer to measure the birefringence of lithium fluoride in shock compression experiments. In previous x-ray diffraction experiments, single crystal [100] LiF has been reported to remain cubic at moderate pressures.

  20. Synthesis and characterization of fluoride fluorescent sensor

    NASA Astrophysics Data System (ADS)

    Hijji, Yousef M.; Wairia, Gilbert; Edwards, Achelle; Iwunze, Maurice; Kennedy, Alvin P., Sr.; Williams, Richard J.

    2004-12-01

    Due to the importance of fluoride in clinical treatment of osteoporosis and its toxicity from over accumulation in bones there is an increased interest in developing selective optical methods for the detection of fluoride anion. Anion recognition and sensing are of interest because of their importance in biological environmental assays and efforts are paid for developing sensitive methods. We synthesized salicylidene furfurylamine 1 and studied spectral properties. Compound 1 fluoresced strongly and the fluorescence was strongly enhanced in the presence of anions as fluoride at low concentrations. A substantially red-shifted emission in acetonitrile was observed. The excitation at 390 nm and the emission was observed at 469nm. Fluoride showed strong absorption and fluorescence enhancement with a significant Stokes shift. Acetate, dihydrogen phosphate, showed small effect, while chloride, bromide had no significant effect.

  1. Study of fluoride corrosion of nickel alloys

    NASA Technical Reports Server (NTRS)

    Gunther, W. H.; Steindler, M. J.

    1969-01-01

    Report contains the results of an investigation of the corrosion resistance of nickel and nickel alloys exposed to fluorine, uranium hexafluoride, and volatile fission product fluorides at high temperatures. Survey of the unclassified literature on the subject is included.

  2. Effects of enamel matrix genes on dental caries are moderated by fluoride exposures

    PubMed Central

    Shaffer, John R.; Carlson, Jenna C.; Stanley, Brooklyn O. C.; Feingold, Eleanor; Cooper, Margaret; Vanyukov, Michael M.; Maher, Brion S.; Slayton, Rebecca L.; Willing, Marcia C.; Reis, Steven E.; McNeil, Daniel W.; Crout, Richard J.; Weyant, Robert J.; Levy, Steven M.; Vieira, Alexandre R.; Marazita, Mary L.

    2014-01-01

    Dental caries (tooth decay) is the most common chronic disease, worldwide, affecting most children and adults. Though dental caries is highly heritable, few caries-related genes have been discovered. We investigated whether 18 genetic variants in the group of nonamelogenin enamel matrix genes (AMBN, ENAM, TUFT1, and TFIP11) were associated with dental caries experience in 13 age- and race-stratified samples from six parent studies (N=3,600). Linear regression was used to model genetic associations and test gene-byfluoride interaction effects for two sources of fluoride: daily tooth brushing and home water fluoride concentration. Meta-analysis was used to combine results across five child and eight adult samples. We observed the statistically significant association of rs2337359 upstream of TUFT1 with dental caries experience via meta-analysis across adult samples (p<0.002) and the suggestive association for multiple variants in TFIP11 across child samples (p<0.05). Moreover, we discovered two genetic variants (rs2337359 upstream of TUFT1 and missense rs7439186 in AMBN) involved in gene-by-fluoride interactions. For each interaction, participants with the risk allele/genotype exhibited greater dental caries experience only if they were not exposed to the source of fluoride. Altogether, these results confirm that variation in enamel matrix genes contributes to individual differences in dental caries liability, and demonstrate that the effects of these genes may be moderated by protective fluoride exposures. In short, genes may exert greater influence on dental caries in unprotected environments, or equivalently, the protective effects of fluoride may obviate the effects of genetic risk alleles. PMID:25373699

  3. Materials processing apparatus development for fluoride glass

    NASA Technical Reports Server (NTRS)

    Smith, Guy A.; Kosten, Sue; Workman, Gary L.

    1994-01-01

    Fluoride glasses have great potential for optical fiber communications due to the high transmittance when no microcrystallites occur during drawing operations. This work has developed apparatus to test the occurrence of microcrystallites during recrystallization in reduced gravity on the KC-135. The apparatus allows fluoride glass fiber, such as ZBLAN, to be melted and recrystallized during both the low and high g portions the parabolic flight.

  4. The role of nonbonding interactions and the presence of fluoride on the conformational isomerism of 1,2-ethanediol

    NASA Astrophysics Data System (ADS)

    Silva, Weslley G. D. P.; Silla, Josué M.; Cormanich, Rodrigo A.; Fernandes, Sergio A.; Freitas, Matheus P.

    2016-07-01

    This work reports the analysis of the effects ruling the conformational preference of 1,2-ethanediol (1,2-ED) using theoretical calculations, since there is no general consensus about the role of intramolecular hydrogen bond on the conformational isomerism of 1,2-ED. While the predominance of the gauche conformers along with the Osbnd Csbnd Csbnd O fragment relative to the trans ones was found to be mainly due to hyperconjugation, the orientation of the hydroxyl groups is better described by a balance between low steric hindrance and high stabilization from hyperconjugation than by intramolecular hydrogen bond. Nevertheless, the presence of a fluoride anion induces a conformational change in 1,2-ED that maximizes hydrogen bonds between the fluoride and the hydroxyl groups. This effect was observed experimentally by the shift of 1H(O) and 19F NMR signals upon complexation, then suggesting that compounds containing the 1,2-ED moiety can be possible anion transporters.

  5. Compression of lithium fluoride to 92 GPa

    NASA Astrophysics Data System (ADS)

    Dong, Haini; Dorfman, Susannah M.; Holl, Christopher M.; Meng, Yue; Prakapenka, Vitali B.; He, Duanwei; Duffy, Thomas S.

    2014-01-01

    The equation of state and compression behavior of lithium fluoride, LiF, have been determined to 92 GPa by X-ray diffraction in a diamond anvil cell. A neon pressure-transmitting medium was used to minimize the effect of differential stress on the sample. Consistent results using multiple pressure standards were obtained. By fitting the pressure-volume data to a Birch-Murnaghan equation of state, the isothermal bulk modulus and its corresponding pressure derivative at zero pressure were determined to be K0=70.1±0.7 GPa, and K‧0=4.3±0.1. If the bulk modulus is fixed at 66.2 GPa, a value well constrained by independent elasticity measurements, we obtain K‧0=4.6±0.1. The bulk modulus and its pressure derivative obtained from this work resolve the large discrepancy in previously reported values of K0 and K‧0 for this material. Consequently, the equation of state of LiF is now sufficiently well constrained to allow its use as a pressure calibrant in high pressure experiments.

  6. New spectrophotometric methods for the determinations of hydrogen sulfide present in the samples of lake water, industrial effluents, tender coconut, sugarcane juice and egg

    NASA Astrophysics Data System (ADS)

    Shyla, B.; Nagendrappa, G.

    2012-10-01

    The new methods are working on the principle that iron(III) is reduced to iron(II) by hydrogen sulfide, catechol and p-toluidine the system 1/hydrogen sulfide the system 2, in acidic medium followed by the reduced iron forming complex with 1,10-phenanthroline with λmax 510 nm. The other two methods are based on redox reactions between electrolytically generated manganese(III) sulfate taken in excess and hydrogen sulfide followed by the unreacted oxidant oxidizing diphenylamine λmax 570 the system 3/barium diphenylamine sulphonate λmax 540 nm, the system 4. The increase/decrease in the color intensity of the dye products of the systems 1 and 2 or 3 and 4 are proportional to the concentration of hydrogen sulfide with its quantification range 0.035-1.40 μg ml-1/0.14-1.40 μg ml-1.

  7. New spectrophotometric methods for the determinations of hydrogen sulfide present in the samples of lake water, industrial effluents, tender coconut, sugarcane juice and egg.

    PubMed

    Shyla, B; Nagendrappa, G

    2012-10-01

    The new methods are working on the principle that iron(III) is reduced to iron(II) by hydrogen sulfide, catechol and p-toluidine the system 1/hydrogen sulfide the system 2, in acidic medium followed by the reduced iron forming complex with 1,10-phenanthroline with λ(max) 510 nm. The other two methods are based on redox reactions between electrolytically generated manganese(III) sulfate taken in excess and hydrogen sulfide followed by the unreacted oxidant oxidizing diphenylamine λ(max) 570 the system 3/barium diphenylamine sulphonate λ(max) 540 nm, the system 4. The increase/decrease in the color intensity of the dye products of the systems 1 and 2 or 3 and 4 are proportional to the concentration of hydrogen sulfide with its quantification range 0.035-1.40 μg ml(-1)/0.14-1.40 μg ml(-1).

  8. Delivery Challenges for Fluoride, Chlorhexidine and Xylitol

    PubMed Central

    Featherstone, John DB

    2006-01-01

    The progression or reversal of dental caries is determined by the balance between pathological and protective factors. It is well established that a) fluoride inhibits demineralization and enhances remineralization, b) chlorhexidine reduces the cariogenic bacterial challenge, and c) xylitol is non-cariogenic and has antibacterial properties. The challenge that we face is how best to deliver these anti-caries entities at true therapeutic levels, over time, to favorably tip the caries balance. High caries risk people, including children with Early Childhood Caries (ECC), are a special challenge, since high cariogenic bacterial activity can override fluoride therapy. Current fluoride and chlorhexidine varnishes deliver all their activity within about 24 hours. Early studies with experimental slow release fluoride devices retained elevated levels of fluoride for months in a therapeutic range but have not been pursued. Preventive dentistry has largely ignored the benefits of reducing the bacterial challenge, partially due to primitive and inadequate delivery systems. For example, Chlorhexidine applied as a rinse partially reduces some bacteria but not others that are hiding within the biofilm. Better antibacterials and better delivery systems are needed. Xylitol delivered by gum or lozenge appears to be effective clinically in reducing cariogenic bacteria and caries levels, but novel systems that deliver therapeutic amounts when needed would be a major advance, especially for young children. Reducing the cariogenic bacterial challenge and enhancing the effect of fluoride by the use of new sustained-delivery systems would have a major effect on dealing with caries as a disease. PMID:16934125

  9. Topical laser application enhances enamel fluoride uptake and tribological properties.

    PubMed

    Jeng, Y-R; Lin, T-T; Huang, J-S; Peng, S-R; Shieh, D-B

    2013-07-01

    Topical fluoride treatment prevents dental caries. However, the resulting calcium-fluoride-like deposits are soft and have poor wear resistance; therefore, frequent treatment is required. Lasers quickly heat surfaces and can be made portable and suitable for oral remedies. We examined the morphology, nanohardness, elastic modulus, nanowear, and fluoride uptake of fluoride-treated enamel followed by CO2 laser irradiation for 5 and 10 sec, respectively. We found that laser treatments significantly increased the mechanical properties of the calcium-fluoride-like deposits. The wear resistance of the calcium-fluoride-like deposits improved about 34% after laser irradiation for 5 sec and about 40% following irradiation for 10 sec. We also found that laser treatments increased fluoride uptake by at least 23%. Overall, laser treatment significantly improved fluoride incorporation into dental tissue and the wear resistance of the protective calcium-fluoride layer.

  10. The effective use of fluorides in public health.

    PubMed Central

    Jones, Sheila; Burt, Brian A.; Petersen, Poul Erik; Lennon, Michael A.

    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 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, systematic reviews summarizing these extensive databases have indicated that water fluoridation and fluoride toothpastes both substantially reduce the prevalence and incidence of dental caries. We present four case studies that illustrate the use of fluoride in modern public health practice, focusing on: recent water fluoridation schemes in California, USA; salt fluoridation in Jamaica; milk fluoridation in Chile; and the development of "affordable" fluoride toothpastes in Indonesia. Common themes are the concern to reduce demands for compliance with fluoride regimes that rely upon action by individuals 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-than-acceptable levels. PMID:16211158

  11. Musculoskeletal problems and fluoride exposure: A cross-sectional study among metal smelting workers.

    PubMed

    Saha, A; Mukherjee, A K; Ravichandran, B

    2016-09-01

    Frequent and repetitive activities in job and awkward postures are shown as major contributors of musculoskeletal problems in most of the occupational health studies; however, efforts to explore newer risk factor are important to plan interventional measures. In this backdrop, this study examined contribution of fluoride exposure to musculoskeletal complaints. A cross-sectional interviewer-administered questionnaire survey was conducted involving 180 randomly selected subjects from a metal smelting industry. Clinical examination of the subjects was also performed to assess their health status and morbidity details. Assessment of personal exposure to particulate and gaseous fluoride at workplace was conducted. Urinary fluoride level was also examined in post-shift samples collected from study subjects. The mean age of the study subjects was 39.1 (±6.7) years. Majority of the workers (42.5%) were engaged in pot room. About 54% workers were suffering from backache and 66% subjects had joint pain. Exposure of workers to both particulate and gaseous fluoride and post-working shift urinary fluoride level was significantly higher in pot-room workers in comparison with all other workers. It was observed that age (odds ratio (OR): 1.62; 95% confidence interval (CI): 1.18-2.34), drinking untreated water (OR: 1.51; 95% CI: 1.03-2.76), working in pot room (OR: 1.44; 95% CI: 1.13-1.91) and urinary fluoride level (OR: 2.71; 95% CI: 1.81-3.75) had significant effects on musculoskeletal complaints. This study concludes that along with other predictors such as nature of work, posture at work and age of worker, exposure to fluoride also has significant role in the occurrence of musculoskeletal morbidity.

  12. Effects of Different Concentrations of Fluoride in Oral Mucosal Cells in Albino Rats

    PubMed Central

    Prakash, P.Ajay; Rao, T.Madhusudhan

    2015-01-01

    Introduction Fluoride has been described to be physiologically essential for the normal development and growth of human beings. However, it is well known that excessive fluoride causes skeletal, nonskeletal and dental complications. Therefore, outlining the cytogenetic effects induced by fluorosis is necessary. Objectives To evaluate the cytomorphology of exfoliated oral mucosal cells among various concentrations of fluoride. Study design: Study group comprised of 12 Albino Wistar rats, categorized into A,B and C groups (fed with 25 ppm,50 ppm and 100 ppm concentration of NaF), each group consisting of 4 rats, with 4 controls (fed with 1ppm concentration of NaF in distilled water). Each group was fed for a period of 42 days. Materials and Methods Cytological smears were taken from the buccal mucosa of each group after 42 days of fluoride administration. The samples were stained with the papanicolaou method and assessed for Cytomorphometrical changes in maximum diameter of nucleus, minimum diameter of nucleus, perimeter of the nucleus, maximum diameter of the cell, minimum diameter of the cell and perimeter of the cell by image analysis software and the results were statistically analysed using SPSS software. Results Mean values of maximum diameter, minimum diameter and perimeter of the nucleus increased in fluoride induced study groups when compared to controls and the results showed that p-value was statistically significant (p-value: 0.000, 0.001). Mean value of maximum diameter, minimum diameter and perimeter of the cell decreased in fluoride induced subjects when compared with controls which were statistically not significant (p-value: 0.791, 0.600 & 0.719). A continuous increase in the nuclear size and decrease in the cell size was identified in fluoride induced groups as compared to controls. Conclusion The observations of our present study revealed that cellular changes occur with severity of fluorosis. These cellular morphological changes may possibly

  13. Analysis of Naturally Occurring Fluoride in Commercial Teas and Estimation of Its Daily Intake through Tea Consumption.

    PubMed

    Peng, Chuan-yi; Cai, Hui-mei; Zhu, Xiao-hui; Li, Da-xiang; Yang, Yun-qiu; Hou, Ru-yan; Wan, Xiao-chun

    2016-01-01

    The aim of this study was to determine the levels of fluoride in commercial teas and to estimate the contribution of tea consumption to the fluoride recommended daily allowance. A total of 558 tea products in 6 categories, green tea, black tea, oolong tea, pu'er tea, white tea, and reprocessed tea, were collected in the period from 2010 to 2013. The levels of fluoride in infusions of these teas were determined by a fluoride-ion selective electrode. The mean fluoride level in all of the tea samples was 85.16 mg/kg. For each category of tea, the mean fluoride levels were 63.04, 99.74, 52.19, 101.67, 159.78, and 110.54 mg/kg for green tea, black tea, white tea, pu'er tea, oolong tea, and reprocessed tea, respectively. The fluoride content of tea from 4 tea zones in descending order were Southern tea zone (111.39 mg/kg) > Southwest tea zone (78.78 mg/kg) > Jiangnan tea zone (71.73 mg/kg) > Jiangbei tea zone (64.63 mg/kg). These areas produced teas with lower fluoride levels than available foreign-produced tea (161.11 mg/kg). The mean chronic daily intake (CDI) was 0.02 mg/(kg•day) or 1.27 mg/kg. Generally, consuming tea from these 6 categories does not result in the intake of excessive amounts of fluoride for the general population.

  14. Fluoride-selective optical sensor based on aluminum(III)-octaethylporphyrin in thin polymeric film: further characterization and practical application.

    PubMed

    Badr, Ibrahim H A; Meyerhoff, Mark E

    2005-10-15

    More detailed analytical studies of a new fluoride-selective optical sensor based on the use of aluminum(III)-octaethylporphyrin and a lipophilic pH indicator (4',5'-dibromofluorescein octadecyl ester; ETH-7075) within a thin plasticized poly(vinyl chloride) film are reported. The sensor exhibits extraordinary optical selectivity for fluoride over a wide range of other anions, including anions with far more positive free energies of hydration (e.g., perchlorate, thiocyanate, nitrate, etc.). UV-visible spectrophotometric studies of the sensing films indicate that fluoride interacts with the Al(III) center of the porphyrin structure, yielding both a change in the Soret band lambda(max) of the porphyrin and a change in the protonation state of the pH indicator within the film. The same change in spectral properties of the metalloporphyrin occurs in the absence of added pH indicator or with added tetraphenylborate derivative anionic sites, but optical responses to fluoride in these cases are shown to be irreversible. The presence of the pH indicator and the simultaneous fluoride/proton coextraction equilibrium chemistry is shown to greatly enhance the reversibility of fluoride binding to the Al(III) porphyrin. Optical response toward fluoride can be observed in the range of 0.1 microM-1.6 mM. Optical selectivity coefficients of <10(-6) for common anions (e.g., sulfate, chloride, nitrate, etc.) and <10(-4) for perchlorate and thiocyanate are obtained. Measurements of fluoride in drinking water via the new optical sensor are shown to correlate well with values obtained for the same samples using a classical LaF3-based fluoride ion-selective electrode method. PMID:16223262

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

    PubMed

    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.

  16. Environmental evaluation of fluoride in drinking water at "Los Altos de Jalisco," in the central Mexico region.

    PubMed

    Hurtado, Roberto; Gardea-Torresdey, Jorge

    Naturally occurring fluoride has been detected and quantified in drinking water in several cities of the "Los Altos de Jalisco" (LAJ) region. LAJ is located in the northeastern part of the state of Jalisco-Mexico, covering an area of 16,410 km2 with a population of 696,318 in 20 municipalities. Drinking water comes mainly from groundwater aquifers, located in the Trans-Mexican Volcanic Belt, which is a volcanic region characterized by hydrothermal activity. Results indicated that water supply from 42% of the municipalities had a fluoride concentration over the Mexican standards of 1.5 mg/L. It is important to notice that there are three cities, Lagos de Moreno (1.66-5.88 mg/L F(-)), Teocaltiche (3.82-18.58 mg/L F(-)), and Encarnación de Díaz (2.58-4.40 mg/L F(-)) where all water samples resulted in fluoride concentration over the maximum contaminant level. The total population from these three cities is over 122,000 inhabitants. Another important city with high levels of fluoride in the water supply was Tepatitlán de Morelos (2 wells with 6.54 and 13.47 mg/L F(-)). In addition to water supply, 30 samples of brand-name bottled water were tested. Surprisingly, 8 samples (27%) demonstrated fluoride level over the standards, mainly Agua de Lagos with 5.27 mg/L. Fluoridated table salt (200-300 mg/kg F(-)) is another important source of fluoride. A large number of people living in the region, mainly school children, might be under adverse health risk because they are consuming contaminated drinking water. It is well known that long-term exposure to water with high levels of fluoride produces severe health problems.

  17. Oral fluoride levels 1 h after use of a sodium fluoride rinse: effect of sodium lauryl sulfate.

    PubMed

    Vogel, Gerald L; Schumacher, Gary E; Chow, Laurence C; Tenuta, Livia M A

    2015-01-01

    Increasing the concentration of free fluoride in oral fluids is an important goal in the use of topical fluoride agents. Although sodium lauryl sulfate (SLS) is a common dentifrice ingredient, the influence of this ion on plaque fluid and salivary fluid fluoride has not been examined. The purpose of this study was to investigate the effect of SLS on these parameters and to examine the effect of this ion on total (or whole) plaque fluoride, an important source of plaque fluid fluoride after a sufficient interval following fluoride administration, and on total salivary fluoride, a parameter often used as a surrogate measure of salivary fluid fluoride. Ten subjects accumulated plaque for 48 h before rinsing with a 12 mmol/l NaF (228 µg/g F) rinse containing or not containing 0.5% (w/w) SLS. SLS had no statistically significant effect on total plaque and total saliva fluoride but significantly increased salivary fluid and plaque fluid fluoride (by 147 and 205%, respectively). These results suggest that the nonfluoride components of topical agents can be manipulated to improve the fluoride release characteristics from oral fluoride reservoirs and that statistically significant change may be observed in plaque fluid and salivary fluid fluoride concentrations that may not be observed in total plaque and total saliva fluoride concentrations.

  18. Fluoride ion contamination in the groundwater of Mithi sub-district, the Thar Desert, Pakistan

    NASA Astrophysics Data System (ADS)

    Rafique, Tahir; Naseem, Shahid; Bhanger, Muhammad I.; Usmani, Tanzil H.

    2008-11-01

    Groundwater samples were collected from various localities of Mithi sub-district of the Thar Desert of Pakistan and analysed for fluoride ion along with other chemical parameters. The area is mainly covered by sand dunes and kaolin/granite at variable depths. Results showed that collected water samples were severely contaminated by the presence of fluoride ion and most of the samples have higher concentration than prescribed WHO standards (1.5 mg/l) for drinking water. Fluoride ion concentrations ranged between 0.09 and 11.63 mg/l with mean and median values of 3.64 and 3.44 mg/l, respectively, in this area whereas, distribution pattern showed high concentrations in the vicinity of Islamkot and Mithi towns. The content of F- has also been correlated with other major ions found in the groundwater of the study area. The positive correlation of F- with Na+ and HCO3 - showed that the water with high Na+ and HCO3 - stabilizes F- ions in the groundwater of the Thar Desert. The pH versus F- plots signifies high fluoride concentration at higher pH values, implying that alkaline environment favours the replacement of exchangeable OH- with F- in the groundwater of Mithi area. The saturation indices (SI) of fluorite (CaF2) and calcite (CaCO3) in the groundwater samples showed that most of the samples are oversaturated with respect to calcite whereas majority of samples have been found under saturated with respect to fluorite. The log TDS and Na/Na+Ca ratio reflected supremacy of weathering of rocks, which promotes the availability of fluoride ions in the groundwater. Piper diagram has been used to classify the hydrofacies. In the cation triangle, all samples are Na-type, while the anion triangle reflects major dominance of Cl-type with a minor influence of HCO3 - and SO4 -.

  19. Removal of fluoride from fluoride contaminated industrial waste water by electrolysis.

    PubMed

    Joshi, Vijaya A; Nanoti, Madan V

    2003-01-01

    Wastewater containing fluoride are generally treated with lime or calcium salt supplemented with aluminium salts. Wastewater generated from different industries does not always behave in the same way due to the presence of interfering contaminants. A number of techniques have been developed and studied for the removal of excessive fluoride. Most of these are based on use of aluminium salt. In alum coagulation the sorption properties of product of hydrolysis of aluminium salts and capacity of fluoride for complex formation plays a very important role. These hydrolysis products of aluminium can be produced by passing direct current through aluminium electrode. The text presented in the paper deals with the various aspect of removal of fluoride by electrolysis using aluminium electrode from fluoride chemical based industrial wastewater. PMID:14672366

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

    USGS Publications Warehouse

    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.