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Sample records for hydrogen fluoride samples

  1. 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...

  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, 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...

  4. 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...

  5. 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...

  6. Electron Collisions with Hydrogen Fluoride

    NASA Astrophysics Data System (ADS)

    Itikawa, Yukikazu

    2017-03-01

    Cross section data are reviewed for electron collisions with hydrogen fluoride. Collision processes considered are total scattering, elastic scattering, excitations of rotational, vibrational, and electronic states, ionization, and dissociative electron attachment. After a survey of the literature, recommended values of the cross sections are determined, as far as possible.

  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. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    PubMed Central

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

    2016-01-01

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

  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 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.

  10. 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.

  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. Unusual hydrogen bonding in L-cysteine hydrogen fluoride.

    PubMed

    Minkov, V S; Ghazaryan, V V; Boldyreva, E V; Petrosyan, A M

    2015-08-01

    L-Cysteine hydrogen fluoride, or bis(L-cysteinium) difluoride-L-cysteine-hydrogen fluoride (1/1/1), 2C3H8NO2S(+)·2F(-)·C3H7NO2S·HF or L-Cys(+)(L-Cys···L-Cys(+))F(-)(F(-)...H-F), provides the first example of a structure with cations of the 'triglycine sulfate' type, i.e. A(+)(A···A(+)) (where A and A(+) are the zwitterionic and cationic states of an amino acid, respectively), without a doubly charged counter-ion. The salt crystallizes in the monoclinic system with the space group P2(1). The dimeric (L-Cys···L-Cys(+)) cation and the dimeric (F(-)···H-F) anion are formed via strong O-H···O or F-H···F hydrogen bonds, respectively, with very short O···O [2.4438 (19) Å] and F···F distances [2.2676 (17) Å]. The F···F distance is significantly shorter than in solid hydrogen fluoride. Additionally, there is another very short hydrogen bond, of O-H···F type, formed by a L-cysteinium cation and a fluoride ion. The corresponding O···F distance of 2.3412 (19) Å seems to be the shortest among O-H···F and F-H···O hydrogen bonds known to date. The single-crystal X-ray diffraction study was complemented by IR spectroscopy. Of special interest was the spectral region of vibrations related to the above-mentioned hydrogen bonds.

  13. 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.

  14. 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.

  15. 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.

  16. Chemical Emergency Preparedness and Prevention Advisory: Hydrogen Fluoride

    EPA Pesticide Factsheets

    This advisory recommends ways Local Emergency Planning Committees (LEPCs) and chemical facilities can reduce risks posed by the presence of hydrogen fluoride (HF), a strong inorganic acid used to manufacture CFCs, in their communities.

  17. 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.

  18. 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.

  19. Pictorial keys to evaluate foliar injury caused by hydrogen fluoride

    SciTech Connect

    Granett, A.L.

    1982-08-01

    Pictorial keys were developed to aid graders in quantifying leaf injury on plants exposed to high concentrations of hydrogen fluoride gas. The keys were based on a pretransformed rating scale of 1 (no injury) to 12 (death of leaf). 5 references, 2 figures, 1 table.

  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.

  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. Acute Symptoms after a Community Hydrogen Fluoride Spill

    PubMed Central

    2013-01-01

    Objectives This study was conducted to describe the demographic characteristics, and clinical signs and symptoms of patients who visited a general hospital because of the release of chemically hazardous hydrogen fluoride that occurred on September 27, 2012 in Gumi City, Korea. Methods The medical records at 1 general hospital 9 km from the accident site were reviewed using a standardized survey format. There were 1,890 non-hospitalized and 12 hospitalized patients exposed to hydrogen fluoride between September 27 and October 13 2012. Results Among the 12 hospitalized patients, 11 were discharged within 1 week and the other was hospitalized for 10 days. The chief complaints were respiratory symptoms such as hemoptysis and shortness of breath, gastrointestinal symptoms, neurologic symptoms, sore throat, and lip burn. The number of non-hospitalized patients exhibited a bimodal distribution, peaking on the first and twelfth days after the accident. Their chief complaints were sore throat (24.1%), headache (19.1%), cough (13.1%), and eye irritation (9.2%); some patients were asymptomatic (6.2%). Patients who visited the hospital within 3 days (early patients) of the spill more often had shortness of breath (27.0%) and nausea (6.3%) as the chief complaints than patients who visited after 3 days (late patients) (3.5% and 2.6%, respectively). However, cough and rhinorrhea were more common in the late patients (14.0% and 3.3%, respectively) than in the early patients (5.0% and 0.0%, respectively). Patients who were closer to the accident site more often had shortness of breath and sputum as the chief complaints than patients who were farther away. The mean serum calcium concentration was 9.37 mg/dL (range: 8.4–11.0 mg/dL); none of the patients had a decreased serum calcium level. Among 48 pulmonary function test results, 4 showed decreased lung function. None of the patients had abnormal urine fluoride levels on the eighth day after exposure. Conclusions Patients

  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. 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

  8. 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.

  9. Chemical emergency preparedness and prevention advisory: Hydrogen fluoride, series 8, No. 3

    SciTech Connect

    Not Available

    1993-07-01

    The advisory recommends ways Local Emergency Planning Committees (LEPCs) and chemical facilities can reduce risks posed by the presence of hydrogen fluoride (HF) in their communities. Hydrogen fluoride, a strong inorganic acid, is produced and used as a gas or liquid without water (i.e., in anhydrous form), or in a water (aqueous) solution. Inhalation of hydrogen fluoride vapor, either in anhydrous form or from water solutions, can cause irritation if the exposure is mild (i.e., low concentration in air for a short time), or severe damage to the respiratory system or death in the case of exposure to high concentrations. Contact with the liquid or vapor can severely burn the skin, eyes, and other tissue. The largest use of hydrogen fluoride is in the manufacture of fluorine-containing chemicals, particularly chlorofluorocarbons (CFCs). Hydrogen fluoride may be used in some petroleum refinery operations, aluminum production, nuclear applications, glass etching and polishing, and metal treating and cleaning. Hydrogen fluoride's acute toxicity prompted EPA to list it as an extremely hazardous substance (EHS), with a threshold planning quantity (TPQ) of 100 pounds, under Section 302 of the Emergency Planning and Community Right-to-Know Act (commonly known as SARA Title III).

  10. 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.

  11. 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.

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

    SciTech Connect

    Hardt, H.; Lamport, D.J.A.

    1982-04-01

    Wood chips from bigtooth aspen (Populus grandidentata Michx.) were saccharified by reaction with hydrogen fluoride either anhydrous or containing up to 10% v/v water. The reaction products were separated into a solid lignin fraction and a water-soluble saccharide fraction. The fluoride content of the lignin (determined after alkaline fusion) was initially about 1 mg/g wood, but was lowered to 0.1 mg/g wood by grinding and washing. Thus little or no chemical binding of fluoride to lignin occurred during hydrogen fluoride (HF) solvolysis. Analysis of the water-soluble fraction by gel filtration on Biogel P2 columns showed a range of low-molecular-weight oligosaccharides an only 10-20% sugar monomers. Thus considerable reversion occurred during HF evacuation. Posthydrolysis conditions were optimized for these reversion products by varying temperature and acid concentration. Optimal conditions at 1 h were 140/sup 0/C with 100mN sulfuric acid or 225mN hydrofluoric acid resulting in monomer yields of > 90% for 0.5% sugar solutions and > 80% for 10% sugar solutions. After reaction of pure cellulose (filter paper) with hydrogen fluoride in the absence of water, and terminating the reaction with calcium carbonate, the reaction intermediate ..cap alpha..-D-glucopyranosylfluride was isolated with a maximal yield of 0.2 g/g paper. Upon purification via paper chromatography glucosyfluoride was identified by its specific rotation and also by gas chromotography-mass spectrometer of its tetra-O-trimethylsilyl derivative.

  13. Exposure to hydrogen fluoride: an experimental study in humans of concentrations of fluoride in plasma, symptoms, and lung function.

    PubMed Central

    Lund, K; Ekstrand, J; Boe, J; Søstrand, P; Kongerud, J

    1997-01-01

    OBJECTIVES: To study the absorption of inhaled hydrogen fluoride (HF) by measuring plasma fluorides and HF concentrations in the breathing zone during exposure to HF. A possible dose-effect relation was investigated by following airway symptoms and lung function-that is, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)-during and after exposure to HF. METHODS: 20 healthy, male volunteers were exposed for one hour to constant HF concentrations that ranged from 0.2 to 5.2 mg/m3; these concentrations are known to occur among potroom workers in the primary aluminium industry. Plasma fluorides were analysed before, during, and after exposure. Symptoms from the eyes and the upper and lower airways were registered and graded from 1 to 5 with a standardised questionnaire. RESULTS: The total symptom score was significantly increased at the end of exposure for all the subjects as a group (P < 0.01) and for the group exposed to HF below the present Norwegian standard for total fluorides 0.6 mg/m3 (P = 0.05). No change was detected in FEV15 although a significant decrease was found in FVC in the group exposed to fluorides below the hygienic standard (n = 9) and for the entire group (n = 23). Almost all the symptoms had disappeared four hours after the end of exposure. Symptom scores from the upper airways were significantly correlated with the HF concentration (r = 0.62, P = 0.002), the change in plasma fluoride concentration (delta C) (r = 0.51, P = 0.01), and the maximum plasma fluoride concentration (Cmax) (r = 0.42, P = 0.05). A significant correlation was also found between the total symptom score for airways and the HF concentration. CONCLUSIONS: The present study showed a strong relation between inhaled HF and concentrations of fluoride in plasma. Upper airway and eye symptoms occurred after one hour of exposure to HF even when below the Norwegian hygienic standard for fluorides. PMID:9072031

  14. 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.

  15. Short-term effects of hydrogen fluoride on Nicotiana tabacum L.

    PubMed

    Döğeroğlu, Tuncay; Ciçek, Arzu; Kara, Serap

    2003-09-01

    Data on the short-term effects of fumigation with hydrogen fluoride (HF) on the response behavior of the Nicotiana tabacum L. cv. St. Karabalar 6265 are being presented. Growth rate, fluoride accumulation in leaves and soils, and degradation in chlorophyll and nicotine contents of the plant species against the variations in two experimental factors, namely the exposure concentration and exposure time parameters, were investigated. Resulting data reveals that the variety selected for this study is not so tolerant to fluoride as generally reported in the literature, if only the individual effects of the pollutant is considered.

  16. A novel colorimetric fluoride sensor based on a semi-rigid chromophore controlled by hydrogen bonding.

    PubMed

    Li, Jiling; Xu, Xiaoyong; Shao, Xusheng; Li, Zhong

    2015-12-01

    A novel semi-rigid latent chromophore E1, containing an amide subunit activated by an adjacent semi-rigid intramolecular hydrogen-bonding (IHB) unit, was designed for the detection of fluoride ion by the 'naked-eye' in CH3CN. Comparative studies on structural analogs (E2, E3, and E4) provided significant insight into the structural and functional role of the amide N-H and IHB segment in the selective recognition of fluoride ions. The deprotonation of the amide N-H followed by the enhancement of intramolecular charge transfer (ICT) induced the colorimetric detection of E1 for fluoride ion.

  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. Inhibition of hydrogen embrittlement of Ni-Ti superelastic alloy in acid fluoride solution by hydrogen peroxide addition.

    PubMed

    Yokoyama, Ken'ichi; Yazaki, Yushin; Sakai, Jun'ichi

    2011-09-01

    Inhibition of the hydrogen embrittlement of Ni-Ti superelastic alloy in an acidulated phosphate fluoride (APF) solution has been attempted by adding various amounts of H(2)O(2). In a 0.2% APF solution, hydrogen absorption is markedly inhibited by adding H(2)O(2), although corrosion is slightly enhanced by increasing the amount of added H(2)O(2). By adding a small amount of H(2)O(2) (0.001 M), in the early stage of immersion, hydrogen embrittlement is inhibited and corrosion is only slightly enhanced. Upon adding H(2)O(2), it appears that the dominant cathodic reactions change from hydrogen evolution to H(2)O(2) reduction reactions, or the surface conditions of the alloy are changed by H(2)O(2) with a high oxidation capability, thereby inhibiting hydrogen absorption. The present study clearly indicates that infinitesimal addition of H(2)O(2) into acid fluoride solutions is effective for the inhibition of the hydrogen embrittlement of the alloy.

  20. Acute Symptoms in Firefighters who Participated in Collection Work after the Community Hydrogen Fluoride Spill Accident

    PubMed Central

    2013-01-01

    Objectives This study aimed to analyze the relationship between clinical status and work characteristics of firefighters and other public officers who engaged on collection duties in the site of the hydrogen fluoride spill that occurred on September 27, 2012, in Gumi City, South Korea. Methods We investigated the clinical status, personal history, and work characteristics of the study subjects and performed physical examination and several clinical examinations, including chest radiography, echocardiography, pulmonary function test, and blood testing in 348 firefighters, police officers, volunteer firefighters, and special warfare reserved force who worked at the hydrogen fluoride spill area. Results The subjects who worked near the accident site more frequently experienced eye symptoms (p = 0.026), cough (p = 0.017), and headache (p = 0.003) than the subjects who worked farther from the accident site. The longer the working hours at the accident area, the more frequently the subjects experienced pulmonary (p = 0.027), sputum (p = 0.043), and vomiting symptoms (p = 0.003). The subjects who did not wear respiratory protective devices more frequently experienced dyspnea than those who wore respiratory protective devices (p = 0.013). In the pulmonary function test, the subjects who worked near the accident site had a higher decease in forced vital capacity than the subjects who worked farther from the site (p = 0.019); however, no statistical association was found between serum calcium/phosphate level, echocardiography result, chest radiographic result, and probation work characteristics. Conclusions The subjects who worked near the site of the hydrogen fluoride spill, worked for an extended period, or worked without wearing respiratory protective devices more frequently experienced upper/lower respiratory, gastrointestinal, and neurological symptoms. Further follow-up examination is needed for the workers who were exposed to hydrogen

  1. 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.

  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.

  4. Test-strip-based fluorometric detection of fluoride in aqueous media with a BODIPY-linked hydrogen-bonding receptor.

    PubMed

    Ashokkumar, Pichandi; Weißhoff, Hardy; Kraus, Werner; Rurack, Knut

    2014-02-17

    The measurement of biologically relevant anions, such as fluoride, is an important task in analytical chemistry, in particular, for dental health and osteoporosis. Although a large number of fluoride probes are known, the applicability under relevant conditions is limited to a few examples. To improve this situation, BODIPY-amidothiourea dyes with varying hydrogen-bond donating strengths were developed, the most H-acidic of which (1 c) could detect F(-) from an inorganic source (NaF) in 50 % aqueous solution (DMSO/water 1:1, v/v) with 0.01 ppm sensitivity through selective fluorescence quenching by a photoinduced electron-transfer (PET) process. Use of the probe and a reference dye with a test-strip assay and a portable and rapidly recording lateral-flow fluorescence reader made determination of F(-) in neat aqueous solutions, such as spiked water samples and toothpaste extracts, possible in a self-referenced manner, achieving a detection limit of 0.2 ppm.

  5. 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.

  6. 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…

  7. Intra- and intermolecular hydrogen bonds in pyrrolylindandione derivatives and their interaction with fluoride and acetate: possible anion sensing properties.

    PubMed

    Sigalov, Mark V; Shainyan, Bagrat A; Chipanina, Nina N; Oznobikhina, Larisa P

    2013-11-07

    The series of push-pull compounds containing the pyrrole ring as a donor and the 1,3-indandione derived moieties as the acceptor unit were synthesized, and strong intramolecular hydrogen bonding in their molecules was studied. In the presence of fluoride and acetate anions their solutions undergo color changes. It was shown by NMR, UV-vis, and quantum chemical calculations including AIM analysis that all these compounds undergo solvent-assisted rupture of the intramolecular hydrogen bond followed by the formation of a strong intermolecular hydrogen bond with fluoride and acetate anions which finally abstract a proton from the pyrrole ring. The insensitivity of the studied compounds to other anions (Cl, Br, HSO4, PF6) is consequence of the instability of the corresponding hydrogen-bonded complexes.

  8. Hydrogen absorption of titanium and nickel-titanium alloys during long-term immersion in neutral fluoride solution.

    PubMed

    Yokoyama, Ken'ichi; Ogawa, Toshio; Asaoka, Kenzo; Sakai, Jun'ichi

    2006-07-01

    Hydrogen absorption of biomedical titanium and Ni-Ti alloys in a neutral fluoride (2.0% NaF) solution for up to 10,000 h at 37 degrees C has been evaluated by means of hydrogen thermal desorption analysis. For alpha titanium (commercial pure titanium), the amount of absorbed hydrogen was, at most, 10-30 mass ppm, and the corrosion product and hydride formation were revealed on the surface of the specimen by X-ray diffraction analysis. Ni-Ti superelastic alloy absorbed approximately 150 mass ppm of hydrogen, which was probably sufficient to result in the pronounced degradation of the mechanical properties, although corrosion was hardly observed. In contrast, hydrogen absorption of alpha-beta titanium (Ti-6Al-4V) and beta titanium (Ti-11.3Mo-6.6Zr-4.3Sn) alloys was negligible, although general corrosion was observed. The results of the present study indicate that the susceptibility of titanium and Ni-Ti alloys to hydrogen absorption in the neutral fluoride solution is different from that in the acidic fluoride solution reported previously.

  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. Hydrogen bonding. Part 19. IR and NMR study of the lower hydrates of choline fluoride and acetylcholine chloride

    NASA Astrophysics Data System (ADS)

    Harmon, Kenneth M.; Avci, Günsel F.; Desantis, Nancy J.; Thiel, Anne C.

    1985-05-01

    Acetylcholine chloride, like choline chloride, forms a liquid salt dihydrate, and a crystalline monohydrate that only exists at reduced pressure; at atmospheric pressure the monohydrate disproportionates into liquid dihydrate and anhydrous acetylcholine chloride. Both choline and acetylcholine chlorides give endothermic dissolution in water. In contrast, choline fluoride gives exothermic dissclution in water, and forms an extra-ordinarily stable monohydrate in which choline cation hydroxyls form strong hydrogen bonds to an H 4O 2F 2-2 cluster anion. Since the hydration behavior of choline fluoride is like that of unsubstituted tetraalkylammonium fluorides, the unusual hydration behavior of choline and acetyline chlorides results from the presence of chloride ion, and is not an intrinsic property of cholinergic cations.

  12. 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).

  13. Friedel-Crafts reaction of benzyl fluorides: selective activation of C-F bonds as enabled by hydrogen bonding.

    PubMed

    Champagne, Pier Alexandre; Benhassine, Yasmine; Desroches, Justine; Paquin, Jean-François

    2014-12-08

    A Friedel-Crafts benzylation of arenes with benzyl fluorides has been developed. The reaction produces 1,1-diaryl alkanes in good yield under mild conditions without the need for a transition metal or a strong Lewis acid. A mechanism involving activation of the C-F bond through hydrogen bonding is proposed. This mode of activation enables the selective reaction of benzylic C-F bonds in the presence of other benzylic leaving groups.

  14. Methods, setup and safe handling for anhydrous hydrogen fluoride cleavage in Boc solid-phase peptide synthesis.

    PubMed

    Muttenthaler, Markus; Albericio, Fernando; Dawson, Philip E

    2015-07-01

    Solid-phase peptide synthesis (SPPS) using tert-butyloxycarbonyl (Boc)/benzyl (Bzl) chemistry is an indispensable technique in many laboratories around the globe, and it provides peptides to the pharmaceutical industry and to thousands of scientists working in basic research. The Boc/Bzl strategy has several advantages, including reliability in the synthesis of long and difficult polypeptides, alternative orthogonality regarding protecting groups and ease of producing C-terminal thioesters for native chemical ligation applications. In this process, anhydrous hydrogen fluoride (HF) is used to remove the side chain protecting groups of the assembled peptide and to release the peptide from the resin, a process typically described as 'HF cleavage'. This protocol describes the general methodology, apparatus setup and safe handling of HF, with the aim of providing comprehensive information on the safe use of this valuable, well-studied and validated cleavage technique. We explain the cleavage mechanism, the physicochemical properties and risks of HF, first aid measures and the correct use of the apparatus. In addition, we provide advice on scavenger selection, as well as a troubleshooting section and video material illustrating key steps of the procedure. The protocol comprises precleavage sample preparation (30 min-2.5 h), complete HF cleavage procedure (2 h) and reaction workup (30 min).

  15. 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.

  16. 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.

  17. 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.

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

    PubMed Central

    Mazack, Michael J. M.; Gao, Jiali

    2014-01-01

    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. PMID:24880295

  19. The effect of sodium fluoride on the stability of cyanide in postmortem blood samples from fire victims.

    PubMed

    McAllister, J L; Roby, R J; Levine, Barry; Purser, David

    2011-06-15

    Assigning a level of significance to cyanide concentrations found in the blood of fire victims is often hampered by the fact that cyanide is inherently unstable in cadavers and in stored blood samples. A few researchers have proposed that sodium fluoride can be used to minimize the instability of cyanide in blood samples; however, controlled studies have not been performed to support validation of this hypothesis. To test the sodium fluoride hypothesis, both treated and control blood samples from 14 autopsied fire victims were tested over a 25-30 day period. A 2% concentration of sodium fluoride was added to the blood samples at the start of testing and the samples were refrigerated between testing intervals. Cyanide concentrations in the treated and control samples were measured between 9 and 11 days post treatment and between 25 and 30 days post treatment. A statistically significant difference was not present between blood cyanide concentrations in treated and control samples between 9 and 11 days. During this time period, although there were small statistically significant increases in both treated and untreated samples the fluctuations were minor. Since the treated and control samples did not exhibit instability between 9 and 11 days, it is not surprising that the sodium fluoride appeared to have no effect. However, a statistically significant difference between blood cyanide concentrations in treated and control samples was observed between 25 and 30 days. Those samples treated with sodium fluoride showed a reduction in blood cyanide variability with virtually no overall change, over a 25-30 day period when compared to control samples, while unconditioned samples showed a significant, average increase of 35%. Based on the findings of this study, it is recommended that 2% sodium fluoride be added to blood samples obtained from fire victims to reduce cyanide instability due to bacteriological activity.

  20. 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.…

  1. Metal fluorides form strong hydrogen bonds and halogen bonds: measuring interaction enthalpies and entropies in solution.

    PubMed

    Libri, Stefano; Jasim, Naseralla A; Perutz, Robin N; Brammer, Lee

    2008-06-25

    The organometallic compound trans-(tetrafluoropyrid-2-yl)bis(triethylphosphine)-fluoronickel(II) (NiF) is shown to serve as a strong hydrogen bond and halogen bond acceptor in solution via intermolecular interactions with the fluoride ligand. The nature of the interactions has been confirmed by multinuclear NMR spectroscopy. Experimental binding constants, enthalpies, and entropies of interaction with hydrogen-bond-donor indole and halogen-bond-donor iodopentafluorobenzene have been determined by 19F NMR titration. In toluene-d8 solution indole forms a 1:1 and 2:1 complex with NiF (K1 = 57.9(3), K2 = 0.58(4)). Interaction enthalpies and entropies are -23.4(2) kJ mol-1 and -44.5(8) J mol-1 K-1, respectively, for the 1:1 complex; -14.8(8) kJ mol-1 and -53(3) J mol-1 K-1, respectively, for the 2:1 complex. In toluene-d8 solution iodopentafluorobenzene forms only a 1:1 complex (K1 = 3.41(9)) with enthalpy and entropy of interaction of -16(1) kJ mol-1 and -42(4) J mol-1 K-1, respectively. A marked solvent effect was observed for the halogen bond interaction. NMR titrations in heptane solution indicated formation of both 1:1 and 2:1 complexes of iodopentafluorobenzene with NiF (K1 = 21.8(2), K2 = 0.22(4)). Interaction enthalpies and entropies are -26(1) kJ mol-1 and -63(4) J mol-1 K-1, respectively, for the 1:1 complex; -21(1) kJ mol-1 and -83(5) J mol-1 K-1, respectively, for the 2:1 complex. There is a paucity of such experimental energetic data particularly for halogen bonds despite substantial structural data. These measurements demonstrate that halogen bonds are competitive with hydrogen bonds as intermolecular interactions and provide a suitable benchmark for theoretical calculations and quantitative input into design efforts in supramolecular chemistry and crystal engineering.

  2. 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

  3. Prevention reference manual: chemical specific. Volume 1. Control of accidental releases of hydrogen fluoride (SCAQMD) (South Coast Air Quality Management District). Final report, May 1986-March 1987

    SciTech Connect

    Davis, D.S.; DeWolf, G.B.; Quass, J.D.

    1987-07-01

    This manual summarizes technical information that will assist in identifying and controlling hydrogen fluoride release hazards specific to the South Coast Air Quality Management District (SCAQMD) of southern California. The SCAQMD has considered a strategy for reducing the risk of a major accidental air release of toxic chemicals. The strategy includes monitoring the storage, handling, and use of certain chemicals and provides guidance to industry and communities. Anhydrous hydrogen fluoride, a corrosive liquid that boils at room temperature, rapidly absorbs moisture to form highly corrosive hydrofluoric acid. Hydrogen fluoride gas has an IDLH (immediately dangerous to life and health) concentration of 20 ppm, which makes it a substantial acute toxic hazard. Reducing the risk associated with an accidental release of hydrogen fluoride involves identifying some of the potential causes of accidental releases that apply to the processes that use hydrogen fluoride in the SCAQMD. The manual identifies examples of potential causes as well as measures that may be taken to reduce the accidental-release risk.

  4. LOCAL INTERSTELLAR NEUTRAL HYDROGEN SAMPLED IN SITU BY IBEX

    SciTech Connect

    Saul, Lukas; Wurz, Peter; Rodriguez, Diego; Scheer, Juergen; Moebius, Eberhard; Schwadron, Nathan; Kucharek, Harald; Leonard, Trevor; Bzowski, Maciej; Fuselier, Stephen; Crew, Geoff; McComas, Dave

    2012-02-01

    Hydrogen gas is the dominant component of the local interstellar medium. However, owing to ionization and interaction with the heliosphere, direct sampling of neutral hydrogen in the inner heliosphere is more difficult than sampling the local interstellar neutral helium, which penetrates deep into the heliosphere. In this paper, we report on the first detailed analysis of the direct sampling of neutral hydrogen from the local interstellar medium. We confirm that the arrival direction of hydrogen is offset from that of the local helium component. We further report the discovery of a variation of the penetrating hydrogen over the first two years of Interstellar Boundary Explorer observations. Observations are consistent with hydrogen experiencing an effective ratio of outward solar radiation pressure to inward gravitational force greater than unity ({mu} > 1); the temporal change observed in the local interstellar hydrogen flux can be explained with solar variability.

  5. 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.

  6. Hydrogen fluoride study: Report to Congress, Section 112(n)(6) Clean Air Act as amended. Final report

    SciTech Connect

    Not Available

    1993-09-01

    Under section 112(n)(6) of the Clean Air Act of 1990, as amended, Congress required EPA to carry out a study of hydrofluoric acid (also called hydrogen fluoride (HF)), to identify potential hazards to public health and the environment considering a range of events including worst-case accidental releases, and to make recommendations for reducing the hazards, if appropriate. The report, developed in response to the Congressional mandate, identifies and evaluates the hazards to the public posed by the production and use of HF. It is not intended to quantify risk to the public from HF.

  7. 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.

  8. 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.

  9. New insights about the hydrogen bonds formed between acetylene and hydrogen fluoride: π ⋯ H, C ⋯ H and F ⋯ H

    NASA Astrophysics Data System (ADS)

    Silva, Denize S.; Oliveira, Boaz G.

    2017-02-01

    A theoretical study of hydrogen bond strength and bond properties in the C2H2 ⋯(HF)-T, C2H2 ⋯ 2(HF)-T, C2H2 ⋯ 2(HF), C2H2 ⋯ 3(HF) and C2H2 ⋯ 4(HF) complexes was carried out at the B3LYP/6-311 ++G(d,p) theory level. In these systems, a strength competition between the π ⋯ H and C ⋯ H interactions was examined. Specifically the F ⋯ H hydrogen bond, its properties were studied through a comparison between the hydrogen fluoride and the higher-order complexes (trimer, tetramer and pentamer). Regarding the electronic properties, the hydrogen bond strength could not be determined by the supermolecule approach. Thus, the hydrogen bond energies were computed via NBO calculations. Additionally to NBO, the ChelpG charge calculations were used to interpret the intermolecular charge transfer. The QTAIM integrations were useful to predict the covalent character of the π ⋯ H, C ⋯ H and F ⋯ H hydrogen bonds. Moreover, values of hybrid orbitals (s and p) and atomic radii were also determined in order to justify the red shifts in the stretch frequencies of the Hsbnd F bonds.

  10. 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

  11. 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(-).

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Infrared spectra of UF sub 6 , WF sub 6 , MoF sub 6 , and SF sub 6 complexes with hydrogen fluoride in solid argon

    SciTech Connect

    Hunt, R.D.; Andrews, L. ); Mac Toth, L. )

    1991-02-07

    UF{sub 6}, WF{sub 6}, MoF{sub 6}, and SF{sub 6} have been codeposited with hydrogen fluoride in excess argon at 12 K. The FTIR spectra of UF{sub 6} and HF revealed a strong UF{sub 6}-HF complex absorption at 3,848 cm{sup {minus}1} along with a weak, broad band at 3,903 cm{sup {minus}1} due to the UF{sub 6}-FH complex. Only one 1:2 complex with a UF{sub 6}-H{sub a}F-H{sub b}F arrangement was detected at higher HF concentrations and sample annealings. Similarly, the HF interaction with tungsten hexafluoride formed two 1:1 complexes. However, the 3,884-cm{sup {minus}1} band due to the anti-hydrogen-bonded complex WF{sub 6}-FH was considerably stronger than the WF{sub 6}-FH{sub b}-FH{sub a} structure. The band positions and relative intensities for the MoF{sub 6} complexes with HF and DF were very comparable to their WF{sub 6} counterparts.

  17. Head-to-tail intermolecular hydrogen bonding of OH and NH groups with fluoride.

    PubMed

    Ashokkumar, Pichandi; Ramakrishnan, Vayalakkavoor T; Ramamurthy, Perumal

    2011-02-07

    To explore the anion-recognition ability of the phenolic hydroxyl group and the amino hydrogen, we synthesized three different acridinedione (ADD) based anion receptors, 1, 2 and 3, having OH, NH, and combination of OH and NH groups, respectively. Absorption, emission and (1)H NMR spectral studies revealed that receptor 1, having only a phenolic OH group, shows selective deprotonation of the hydroxyl proton towards F(-), which results in an "ON-OFF"-type signal in the fluorescence spectral studies. Receptor 2, which only has an amino hydrogen, also shows deprotonation of the amino hydrogen with F(-), whereas receptor 3 (having both OH and NH groups) shows head-to-tail intermolecular hydrogen bonding of OH and NH groups with F(-) prior to deprotonation. The observation of hydrogen bonding of the OH and NH groups in a combined solution of 1 and 2 with F(-) in a head-to-tail hetero-intermolecular fashion, and the absence of head-to-head and tail-to-tail intermolecular hydrogen bonding in 1 and 2 with F(-), prove that the difference in the acidity of the OH and NH protons leads to the formation of an intermolecular hydrogen-bonding complex with F(-) prior to deprotonation. The presence of this hydrogen-bonding complex was confirmed by absorption spectroscopy, 3D emission contour studies, and (1)H NMR titration.

  18. Electronic structure of H2S, SF2, and HSF and implications for hydrogen-substituted hypervalent sulfur fluorides.

    PubMed

    Lindquist, Beth A; Woon, David E; Dunning, Thom H

    2014-02-20

    It is well known that hypervalent molecules are more stable with very electronegative ligands such as fluorine. For example, while SF6 is uniquely stable and experimentally well characterized and many of the features of SF4 have been characterized, neither H4S nor H6S has been observed. Furthermore, no hypervalent sulfur species with mixed hydrogen and fluorine ligands have been experimentally characterized to date. In this work, we present detailed calculations of the electronic structure of H2S, SF2, and HSF. While all three compounds have similar bent singlet ground states, the potential energy surfaces of various low lying electronic states as a function of bond angle reveal very different behaviors, in particular for linear geometries. We use the disparate bonding motifs of the low-lying triplet states to rationalize the differences between SF4 and the hypothetical H4S molecule. We also make predictions about the effects of hydrogen substitution on the energetics and geometries of hypervalent sulfur fluoride compounds.

  19. 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.

  20. 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 −}.

  1. Fluoridated Water

    MedlinePlus

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

  2. 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 ...

  3. Interaction between nuclear graphite and molten fluoride salts: a synchrotron radiation study of the substitution of graphitic hydrogen by fluoride ion.

    PubMed

    Yang, Xinmei; Feng, Shanglei; Zhou, Xingtai; Xu, Hongjie; Sham, T K

    2012-01-26

    The interaction between nuclear graphite and molten fluoride salts (46.5 mol % LiF/11.5 mol % NaF/42 mol % KF) is investigated by synchrotron X-ray diffraction and C K-edge X-ray absorption near-edge structure (XANES). It is found that there are a large number of H atoms in IG-110 nuclear graphite, which is attributed to the residual C-H bond after the graphitization process of petroleum coke and pitch binder. The elastic recoil detection analysis indicates that H atoms are uniformly distributed in IG-110 nuclear graphite, in excellent agreement with the XANES results. The XANES results indicate that the immersion in molten fluoride salts at 500 °C led to H atoms in nuclear graphite partly substituted by the fluorine from fluoride salts to form C-F bond. The implications of these findings are discussed.

  4. Norharmane: old yet highly selective dual channel ratiometric fluoride and hydrogen sulfate ion sensor.

    PubMed

    Mallick, Arabinda; Katayama, Tetsuro; Ishibasi, Yukihide; Yasuda, Masakazu; Miyasaka, Hiroshi

    2011-01-21

    Norharmane provides a simple unexplored class of anion receptor, that allows for the ratiometric selective detection of F(-) and HSO(4)(-) ions. The presence of a strong base can easily form hydrogen bonds with the acidic hydrogen bond donor moiety and the relatively strong acid can easily protonate the basic hydrogen bond acceptor moiety, which can modulate the optical response and can detect the anions efficiently with high selectivity. In view of that, it is promising to conceive the use of these systems in various sensing applications as well as in other situations, such as anion transport and purification, where the availability of cheap and easy-to-make anion receptors, would be advantageous.

  5. Optimized method for dissolved hydrogen sampling in groundwater.

    PubMed

    Alter, Marcus D; Steiof, Martin

    2005-06-01

    Dissolved hydrogen concentrations are used to characterize redox conditions of contaminated aquifers. The currently accepted and recommended bubble strip method for hydrogen sampling (Wiedemeier et al., 1998) requires relatively long sampling times and immediate field analysis. In this study we present methods for optimized sampling and for sample storage. The bubble strip sampling method was examined for various flow rates, bubble sizes (headspace volume in the sampling bulb) and two different H2 concentrations. The results were compared to a theoretical equilibration model. Turbulent flow in the sampling bulb was optimized for gas transfer by reducing the inlet diameter. Extraction with a 5 mL headspace volume and flow rates higher than 100 mL/min resulted in 95-100% equilibrium within 10-15 min. In order to investigate the storage of samples from the gas sampling bulb gas samples were kept in headspace vials for varying periods. Hydrogen samples (4.5 ppmv, corresponding to 3.5 nM in liquid phase) could be stored up to 48 h and 72 h with a recovery rate of 100.1+/-2.6% and 94.6+/-3.2%, respectively. These results are promising and prove the possibility of storage for 2-3 days before laboratory analysis. The optimized method was tested at a field site contaminated with chlorinated solvents. Duplicate gas samples were stored in headspace vials and analyzed after 24 h. Concentrations were measured in the range of 2.5-8.0 nM corresponding to known concentrations in reduced aquifers.

  6. 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.

  7. 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

  8. 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.

  9. Ab initio path integral simulations for the fluoride ion-water clusters: competitive nuclear quantum effect between F(-)-water and water-water hydrogen bonds.

    PubMed

    Kawashima, Yukio; Suzuki, Kimichi; Tachikawa, Masanori

    2013-06-20

    Small hydrated fluoride ion complexes, F(-)(H2O)n (n = 1-3), have been studied by ab initio hybrid Monte Carlo (HMC) and ab initio path integral hybrid Monte Carlo (PIHMC) simulations. Because of the quantum effect, our simulation shows that the average hydrogen-bonded F(-)···HO distance in the quantum F(-)(H2O) is shorter than that in the classical one, while the relation inverts at the three water molecular F(-)(H2O)3 cluster. In the case of F(-)(H2O)3, we have found that the nuclear quantum effect enhances the formation of hydrogen bonds between two water molecules. In F(-)(H2O)2 and F(-)(H2O)3, the nuclear quantum effect on two different kinds of hydrogen bonds, F(-)-water and water-water hydrogen bonds, competes against each other. In F(-)(H2O)3, thus, the nuclear quantum effect on the water-water hydrogen bond leads to the elongation of hydrogen-bonded F(-)···HO distance, which we suggest this as the possible origin of the structural inversion from F(-)(H2O) to F(-)(H2O)3.

  10. Fluoride content of infant foods.

    PubMed

    Steele, Jaime L; Martinez-Mier, E Angeles; Sanders, Brian J; Jones, James E; Jackson, Richard D; Soto-Rojas, Armando E; Tomlin, Angela M; Eckert, George J

    2014-01-01

    Excessive fluoride consumption during the first 2 years of life is associated with an increased risk of dental fluorosis. Estimates of fluoride intake from various sources may aid in determining a child's risk for developing fluorosis. This study sought to assess the fluoride content of commercially available foods for infants, and to guide dentists who are advising parents of young children about fluoride intake. Three samples each of 20 different foods (including fruits and vegetables, as well as chicken, turkey, beef/ham, and vegetarian dinners) from 3 manufacturers were analyzed (in duplicate) for their fluoride content. Among the 360 samples tested, fluoride concentration ranged from 0.007-4.13 μg fluoride/g food. All foods tested had detectable amounts of fluoride. Chicken products had the highest mean levels of fluoride, followed by turkey products. Consuming >1 serving per day of the high fluoride concentration products in this study would place children over the recommended daily fluoride intake. Fluoride from infant foods should be taken into account when determining total daily fluoride intake.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Simple determination of fluoride in biological samples by headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry.

    PubMed

    Kwon, Sun-Myung; Shin, Ho-Sang

    2015-08-14

    A simple and convenient method to detect fluoride in biological samples was developed. This method was based on derivatization with 2-(bromomethyl)naphthalene, headspace solid phase microextraction (HS-SPME) in a vial, and gas chromatography-tandem mass spectrometric detection. The HS-SPME parameters were optimized as follows: selection of CAR/PDMS fiber, 0.5% 2-(bromomethyl)naphthalene, 250 mg/L 15-crown-5-ether as a phase transfer catalyst, extraction and derivatization temperature of 95 °C, heating time of 20 min and pH of 7.0. Under the established conditions, the lowest limits of detection were 9 and 11 μg/L in 1.0 ml of plasma and urine, respectively, and the intra- and inter-day relative standard deviation was less than 7.7% at concentrations of 0.1 and 1.0 mg/L. The calibration curve showed good linearity of plasma and urine with r=0.9990 and r=0.9992, respectively. This method is simple, amenable to automation and environmentally friendly.

  16. Dentifrice Fluoride

    NASA Astrophysics Data System (ADS)

    Rakita, Philip E.

    2004-05-01

    The effectiveness of the fluoride ion in lowering the incidence of dental caries is a major factor in the field of dental health. Observations and research studies in the first half of the 20th century have lead to the widespread adoption of fluoridated water and the use of inorganic fluoride compounds in oral care products, such as toothpaste and dental rinses. This article provides a brief review of the types of compounds used and the chemistry involved.

  17. 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, ...

  18. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    DOEpatents

    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.

  19. 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.

  20. Total fluoride intake and excretion in children up to 4 years of age living in fluoridated and non-fluoridated areas.

    PubMed

    Zohoori, F V; Buzalaf, M A R; Cardoso, C A B; Olympio, K P K; Levy, F M; Grizzo, L T; Mangueira, D F B; Sampaio, F C; Maguire, A

    2013-10-01

    Fractional fluoride retention is important during the early years of life when considering the risk of development of dental fluorosis. This study aimed to measure fractional fluoride retention in young children. The objectives were to investigate the relationships between fractional fluoride retention and total daily fluoride intake, age, and body mass index (BMI). Twenty-nine healthy children, up to 4 yr of age, participated; 14 lived in a fluoridated area (0.64 μg ml(-1) of fluoride in drinking water) and 15 lived in a non-fluoridated area (0.04 μg ml(-1) of fluoride in drinking water). The total daily fluoride intake of each child was calculated from the daily dietary fluoride intake and toothpaste ingestion (if fluoride toothpaste was used). Total daily fluoride excretion was measured by collecting voided urine and faeces over a 24-h period, and fractional fluoride retention was calculated by dividing the amount of fluoride retained in the body (total daily fluoride intake minus total daily fluoride excretion) by the total daily fluoride intake. Nine children were excluded from data analysis because of suspected invalid samples. Mean (range) fractional fluoride retention for the remaining 20 children was 0.61 (0.06-0.98). There were no statistically significant correlations between fractional fluoride retention and either age or BMI. However, fractional fluoride retention was correlated with total daily fluoride intake: fractional fluoride retention = 1 - exp (-C × total daily fluoride intake), where C = 28.75 (95% CI = 19.75-37.75). The wide variation in fluoride retention in young children could have important implications when recommendations for fluoride use are being considered.

  1. The application of the fluoride reactivation process to the detection of sarin and soman nerve agent exposures in biological samples.

    PubMed

    Adams, T K; Capacio, B R; Smith, J R; Whalley, C E; Korte, W D

    2004-02-01

    The fluoride reactivation process was evaluated for measuring the level of sarin or soman nerve agents reactivated from substrates in plasma and tissue from in vivo exposed guinea pigs (Cava porcellus), in blood from in vivo exposed rhesus monkeys (Macaca mulatta), and in spiked human plasma and purified human albumin. Guinea pig exposures ranged from 0.05 to 44 LD50, and reactivated nerve agent levels ranged from 1.0 ng/mL in plasma obtained from 0.05 LD50 sarin-exposed guinea pigs to an average of 147 ng/g in kidney tissue obtained from two 2.0 LD50 soman-exposed guinea pigs. Positive dose-response relationships were observed in all low-level, 0.05 to 0.4 LD50, exposure studies. An average value of 2.4 ng/mL for reactivated soman was determined in plasma obtained from two rhesus monkeys three days after a 2 LD50 exposure. Of the five types of guinea pig tissue studied, plasma, heart, liver, kidney and lung, the lung and kidney tissue yielded the highest amounts of reactivated agent. In similar tissue and with similar exposure procedures, reactivated soman levels were greater than reactivated sarin levels. Levels of reactivated agents decreased rapidly with time while the guinea pig was alive, but decreased much more slowly after death. This latter chemical stability should facilitate forensic retrospective identification. The high level of reactivated agents in guinea pig samples led to the hypothesis that the principal source of reactivated agent came from the agent-carboxylesterase adduct. However, there could be contributions from adducts of the cholinesterases, albumin and fibrous tissue, as well. Quantitative analysis was performed with a GC-MS system using selected ion monitoring of the 99 and 125 ions for sarin and the 99 and 126 ions for soman. Detection levels were as low as 0.5 ng/mL. The assay was precise and easy to perform, and has potential for exposure analysis from organophosphate nerve agents and pesticides in other animal species.

  2. Proposed replacement and operation of the anhydrous hydrogen fluoride supply and fluidized-bed chemical processing systems at Building 9212, Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1995-09-01

    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 located within the Y-12 Plant on DOE`s Oak Ridge Reservation in Oak Ridge, Tennessee. The proposed replacement system would be based upon modern design criteria and safety analyses. The replacement AHF supply and distribution system equipment would be located on the existing Dock 8/8A at Building 9212. Utilities would be extended to the dock to service the process equipment. The following process equipment modules would be prefabricated for installation at the modified dock: an AHF cylinder enclosure, an AHF supply manifold and vaporizer module, an AHF sump tank and transfer skid, and an AHF supply off-gas scrubber assembly module. The fluidized-bed reactor system would be constructed in an area adjacent to the existing system in Building 9212. The replacement equipment would consist of a new reduction fluidized-bed reactor, a hydrofluorination fluidized-bed reactor, and associated air emission control equipment. The no-action alternative, which is the continued operation of the existing AHF supply and fluidized-bed reactor systems, was also evaluated.

  3. Device for sampling and enriching impurities in hydrogen comprising hydrogen-permeable membrane

    DOEpatents

    Ahmed, Shabbir; Papadias, Dionissios D.; Lee, Sheldon D. H.; Kumar, Romesh

    2017-01-31

    Provided herein are methods and devices to enrich trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentration of impurities so as to allow the detection of the impurities using commonly-available detection methods.

  4. 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).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Quantitation of fluoride ion released sarin in red blood cell samples by gas chromatography-chemical ionization mass spectrometry using isotope dilution and large-volume injection.

    PubMed

    Jakubowski, E M; McGuire, J M; Evans, R A; Edwards, J L; Hulet, S W; Benton, B J; Forster, J S; Burnett, D C; Muse, W T; Matson, K; Crouse, C L; Mioduszewski, R J; Thomson, S A

    2004-01-01

    A new method for measuring fluoride ion released isopropyl methylphosphonofluoridate (sarin, GB) in the red blood cell fraction was developed that utilizes an autoinjector, a large-volume injector port (LVI), positive ion ammonia chemical ionization detection in the SIM mode, and a deuterated stable isotope internal standard. This method was applied to red blood cell (RBC) and plasma ethyl acetate extracts from spiked human and animal whole blood samples and from whole blood of minipigs, guinea pigs, and rats exposed by whole-body sarin inhalation. Evidence of nerve agent exposure was detected in plasma and red blood cells at low levels of exposure. The linear method range of quantitation was 10-1000 pg on-column with a detection limit of approximately 2-pg on-column. In the course of method development, several conditions were optimized for the LVI, including type of injector insert, injection volume, initial temperature, pressure, and flow rate. RBC fractions had advantages over the plasma with respect to assessing nerve agent exposure using the fluoride ion method especially in samples with low serum butyrylcholinesterase activity.

  10. Drinking water fluoridation and bone.

    PubMed

    Allolio, B; Lehmann, R

    1999-01-01

    Drinking water fluoridation has an established role in the prevention of dental caries, but may also positively or negatively affect bone. In bone fluoride is incorporated into hydroxylapatite to form the less soluble fluoroapatite. In higher concentrations fluoride stimulates osteoblast activity leading to an increase in cancellous bone mass. As optimal drinking water fluoridation (1 mg/l) is widely used, it is of great interest, whether long-term exposition to artificial water fluoridation has any impact on bone strength, bone mass, and -- most importantly -- fracture rate. Animal studies suggest a biphasic pattern of the effect of drinking water fluoridation on bone strength with a peak strength at a bone fluoride content of 1200 ppm followed by a decline at higher concentrations eventually leading to impaired bone quality. These changes are not paralleled by changes in bone mass suggesting that fluoride concentrations remain below the threshold level required for activation of osteoblast activity. Accordingly, in most epidemiological studies in humans bone mass was not altered by optimal drinking water fluoridation. In contrast, studies on the effect on hip fracture rate gave conflicting results ranging from an increased fracture incidence to no effect, and to a decreased fracture rate. As only ecological studies have been performed, they may be biased by unknown confounding factors -- the so-called ecological fallacy. However, the combined results of these studies indicate that any increase or decrease in fracture rate is likely to be small. It has been calculated that appropriately designed cohort studies to solve the problem require a sample size of >400,000 subjects. Such studies will not be performed in the foreseeable future. Future investigations in humans should, therefore, concentrate on the effect of long-term drinking water fluoridation on bone fluoride content and bone strength.

  11. 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.

  12. 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)

  13. 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.

  14. 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.

  15. 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)

  16. Effectiveness of water spray mitigation systems for accidental releases of hydrogen fluoride. Volume 9. Wind tunnel modeling of fire monitors for HF vapor cloud mitigation, volume 1. Final report

    SciTech Connect

    Petersen, R.L.; Ratcliff, M.A.; Heskestad, G.; Parce, D.K.

    1992-05-01

    The hazards of hydrogen fluoride (HF) have long been recognized. Standard operating practices have been aimed at on minimizing the possibility of a release and mitigating the effects if a release should occur. These practices are continually monitored and improved to maximize safety protection based on the available technical data. The recent program targeted further improvements based on new technical data. The volume presents the results of wind tunnel simulations of water monitors and a surrogate gas for HF to quantify the effect of water spray/HF release configuration variables on the performance of multiple water monitors.

  17. Development of a reaxff reactive force field for silicon/oxygen/hydrogen/fluoride interactions and applications to hydroxylation and friction

    NASA Astrophysics Data System (ADS)

    Yeon, Jejoon

    higher strain energy. In addition, we found three distinct hydroxylation paths -- H3O+ formation reaction from the adsorbed water, proton donation from H3O+, and the direct dissociation of the adsorbed water molecule. Because water molecules and their hydrogen bond network behave differently with respect to temperature ranges, silanol formation is also affected by temperature. The formation of surface hydroxyl in an amorphous silica double slit displays a similar tendency: SiOH formation prefers high-strain sites. Silanol formation related with H3O + formation and dissociation is observed in hydroxylation of amorphous SiO2, similar with the results from silica nano wire simulation. These results are particularly relevant to the tribological characteristics of surfaces, enabling the prediction of the attachment site of the lubrication film on silica surfaces with a locally strained geometry.

  18. 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.

  19. Competition between Al2O3 atomic layer etching and AlF3 atomic layer deposition using sequential exposures of trimethylaluminum and hydrogen fluoride.

    PubMed

    DuMont, Jaime W; George, Steven M

    2017-02-07

    The thermal atomic layer etching (ALE) of Al2O3 can be performed using sequential and self-limiting reactions with trimethylaluminum (TMA) and hydrogen fluoride (HF) as the reactants. The atomic layer deposition (ALD) of AlF3 can also be accomplished using the same reactants. This paper examined the competition between Al2O3 ALE and AlF3 ALD using in situ Fourier transform infrared (FTIR) vibrational spectroscopy measurements on Al2O3 ALD-coated SiO2 nanoparticles. The FTIR spectra could observe an absorbance loss of the Al-O stretching vibrations during Al2O3 ALE or an absorbance gain of the Al-F stretching vibrations during AlF3 ALD. The transition from AlF3 ALD to Al2O3 ALE occurred versus reaction temperature and was also influenced by the N2 or He background gas pressure. Higher temperatures and lower background gas pressures led to Al2O3 ALE. Lower temperatures and higher background gas pressures led to AlF3 ALD. The FTIR measurements also monitored AlCH3* and HF(*) species on the surface after the TMA and HF reactant exposures. The loss of AlCH3* and HF(*) species at higher temperatures is believed to play a vital role in the transition between AlF3 ALD at lower temperatures and Al2O3 ALE at higher temperatures. The change between AlF3 ALD and Al2O3 ALE was defined by the transition temperature. Higher transition temperatures were observed using larger N2 or He background gas pressures. This correlation was associated with variations in the N2 or He gas thermal conductivity versus pressure. The fluorination reaction during Al2O3 ALE is very exothermic and leads to temperature rises in the SiO2 nanoparticles. These temperature transients influence the Al2O3 etching. The higher N2 and He gas thermal conductivities are able to cool the SiO2 nanoparticles more efficiently and minimize the size of the temperature rises. The competition between Al2O3 ALE and AlF3 ALD using TMA and HF illustrates the interplay between etching and growth and the importance of

  20. Thermal Atomic Layer Etching of SiO2 by a "Conversion-Etch" Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride.

    PubMed

    DuMont, Jaime W; Marquardt, Amy E; Cano, Austin M; George, Steven M

    2017-03-22

    The thermal atomic layer etching (ALE) of SiO2 was performed using sequential reactions of trimethylaluminum (TMA) and hydrogen fluoride (HF) at 300 °C. Ex situ X-ray reflectivity (XRR) measurements revealed that the etch rate during SiO2 ALE was dependent on reactant pressure. SiO2 etch rates of 0.027, 0.15, 0.20, and 0.31 Å/cycle were observed at static reactant pressures of 0.1, 0.5, 1.0, and 4.0 Torr, respectively. Ex situ spectroscopic ellipsometry (SE) measurements were in agreement with these etch rates versus reactant pressure. In situ Fourier transform infrared (FTIR) spectroscopy investigations also observed SiO2 etching that was dependent on the static reactant pressures. The FTIR studies showed that the TMA and HF reactions displayed self-limiting behavior at the various reactant pressures. In addition, the FTIR spectra revealed that an Al2O3/aluminosilicate intermediate was present after the TMA exposures. The Al2O3/aluminosilicate intermediate is consistent with a "conversion-etch" mechanism where SiO2 is converted by TMA to Al2O3, aluminosilicates, and reduced silicon species following a family of reactions represented by 3SiO2 + 4Al(CH3)3 → 2Al2O3 + 3Si(CH3)4. Ex situ X-ray photoelectron spectroscopy (XPS) studies confirmed the reduction of silicon species after TMA exposures. Following the conversion reactions, HF can fluorinate the Al2O3 and aluminosilicates to species such as AlF3 and SiOxFy. Subsequently, TMA can remove the AlF3 and SiOxFy species by ligand-exchange transmetalation reactions and then convert additional SiO2 to Al2O3. The pressure-dependent conversion reaction of SiO2 to Al2O3 and aluminosilicates by TMA is critical for thermal SiO2 ALE. The "conversion-etch" mechanism may also provide pathways for additional materials to be etched using thermal ALE.

  1. Long-term in vitro fluoride release and rerelease from orthodontic bonding materials containing fluoride.

    PubMed

    Cohen, Warren J; Wiltshire, William A; Dawes, Colin; Lavelle, Chris L B

    2003-11-01

    The purpose of this study was to compare in vitro long-term (30 month) fluoride release and rerelease rates (after fluoride exposure) from 3 orthodontic bonding materials containing fluoride and 1 without fluoride. Ten samples of each material (Python, TP Orthodontics, LaPorte, Ind; Assure, Reliance Orthodontic Products, Itasca, Ill; Fuji Ortho LC, GC America, Alsip, Ill; and Transbond XT, 3M Unitek, Monrovia, Calif) were fabricated and stored in deionized distilled water at 37 degrees C. Five samples had fluoride-release rates measured at days 546, 637, 730, 821, and 913 after initial fabrication, and 5 samples were exposed to fluoride (Nupro 2% NaF gel, Dentsply Canada, Woodbridge, Ontario, Canada) for 4 minutes at day 535 and had measurements taken on days 546, 548, 552, 575, 637, 730, 821, and 913. To prevent cumulative measurements, the storage solutions were changed 24 hours before measurement. Statistically significant differences were found in fluoride-release rates (P <.0001), with Fuji Ortho LC releasing the most fluoride, followed by Python and Assure at all time points in the nonfluoride exposed group. In the fluoride-exposed group, there were significant differences in fluoride release (P <.0001), with Fuji Ortho LC releasing the most fluoride. A "burst-effect" pattern of fluoride release was seen after fluoride exposure for all materials. It was concluded that Fuji Ortho LC, Assure, and Python might have sufficient long-term fluoride-release rates to reduce white spot formation, and all are recommended as suitable fluoride-releasing orthodontic bonding materials.

  2. Comprehensive gas chromatography with Time of Flight MS and large volume introduction for the detection of fluoride-induced regenerated nerve agent in biological samples.

    PubMed

    van der Meer, J A; Trap, H C; Noort, D; van der Schans, M J

    2010-05-15

    Recently, several methods have been developed to verify exposure to nerve agents. Most of these methods, such as the fluoride reactivation technique and the analysis of inhibited phosphonylated butyrylcholinesterase (BuChE), are based on mass spectrometry. The high specificity of the mass spectrometer might also imply a disadvantage, because the acquisition mass, i.e. the identity of the analyte must be known beforehand in order to direct the MS analysis in the most sensitive mode. In real cases, the identity of the nerve agent is not always known beforehand and the mass spectrometer should be operated in a scanning mode, with the consequence that sensitivity of the method will be lower. Comprehensive GC, or GC x GC, is a technique which offers enhanced separation. The implied larger selectivity of the GC separation allows mass spectrometry to be conducted in a less specific, scanning, mode. By the use of this configuration, the identity of the nerve agent does not have to be known beforehand but can be traced. In order to be able to detect lower concentrations and assess lower exposure levels, a large volume injection technique was developed allowing sample sizes up to 100 microL. The technique was tested with plasma samples that had been inhibited with various nerve agents. Subsequently, the cholinesterase-bound nerve agent was regenerated by the fluoride reactivation technique. Using the newly developed comprehensive GC-MS method it was possible to detect nerve agent at an exposure level of 1% BuChE inhibition, which is approximately 70 pg nerve agent/mL. These low exposure levels cannot be verified with a cholinesterase (ChE) activity assay. Moreover, the identity of the regenerated nerve agent was verified by the mass spectrum that was generated by the TOF mass spectrometer. This paper presents a technique able to deliver full-scan data on the analysis of nerve agents in biomedical samples at relevant exposure levels (1% BuChE inhibition). This full-scan data

  3. 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.

  4. Fluoride absorption: independence from plasma fluoride levels

    SciTech Connect

    Whitford, G.M.; Williams, J.L.

    1986-04-01

    The concept that there are physiologic mechanisms to homeostatically regulate plasma fluoride concentrations has been supported by results in the literature suggesting an inverse relationship between plasma fluoride levels and the absorption of the ion from the gastrointestinal tract of the rat. The validity of the relationship was questioned because of possible problems in the experimental design. The present work used four different methods to evaluate the effect of plasma fluoride levels on the absorption of the ion in rats: (i) the percentage of the daily fluoride intake that was excreted in the urine; (ii) the concentration of fluoride in femur epiphyses; (iii) the net areas under the time-plasma fluoride concentration curves after intragastric fluoride doses; and (iv) the residual amounts or fluoride in the gastrointestinal tracts after the intragastric fluoride doses. None of these methods indicated that plasma fluoride levels influence the rate or the degree or fluoride absorption. It was concluded that, unless extremely high plasma fluoride levels are involved (pharmacologic or toxic doses), the absorption of the ion is independent of plasma levels. The results provide further evidence that plasma fluoride concentrations are not homeostatically regulated.

  5. 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

  6. Interval sampling of breath hydrogen (H2) as an index of lactose malabsorption in lactase-deficient subjects.

    PubMed

    Welsh, J D; Payne, D L; Manion, C; Morrison, R D; Nichols, M A

    1981-08-01

    Interval sampling of breath hydrogen content was used in lactose malabsorbers: (1) to compare hydrogen responses following increasing oral doses of lactose in milk and aqueous solutions; (2) to determine the reproducibility of interval breath sampling, and (3) to compare carbohydrate malabsorption following ingestion of either regular milk or milk containing Lactobacillus acidophilus. Significant differences in breath hydrogen responses due to increasing amounts of lactose in milk and aqueous solutions were observed. The individual breath hydrogen responses were reproducible using the same lactose dose on different days. There was no significant difference in breath hydrogen responses or symptoms following administration of either regular milk or milk containing Lactobacillus acidophilus. Breath hydrogen sampling at intervals, as performed in these studies, provides a sensitive and reproducible index of lactose malabsorption.

  7. Fluorescent sensing of fluoride in cellular system.

    PubMed

    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

  8. 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

  9. A path sampling study of Ru-hydride-catalyzed H2 hydrogenation of ethylene.

    PubMed

    Rowley, Christopher N; Woo, Tom K

    2008-06-11

    Ab initio molecular dynamics and transition path sampling were used to examine the dynamics of the H2 hydrogenation of ethylene with the catalyst RuHCl(CO)(PR3)2. The simulations showed H2 is coordinated very weakly to the metal until ethylene insertion, where it is cleaved into a dihydride intermediate. The dihydride has a shorter lifetime than RRKM theory predicts, due to the localization of kinetic energy into Ru-H vibrational modes after the insertion step.

  10. 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.

  11. 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

    2010-10-06

    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.

  12. Fluoride anion sensing mechanism of 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonded supramolecular assembly: photoinduced electron transfer and partial configuration change.

    PubMed

    Chen, Jun-Sheng; Zhou, Pan-Wang; Li, Guang-Yue; Chu, Tian-Shu; He, Guo-Zhong

    2013-05-02

    The fluoride anion sensing mechanism of 6-methyl-5-(9-methylene-anthracene)-(2-butylureido-4[1H]-pyrimidinone) (AnUP) has been investigated using the DFT/TDDFT method. The theoretical results indicate that the proton of the N3-H3 group in pyrimidine moiety is captured by the added fluoride anion and then deprotonated. The calculated vertical excitation energies of AnUP-dimer and its deprotonated form agree well with the experimental results. The molecular orbital analysis demonstrates that the first excited state (S1) of AnUP-dimer is a local excited state with a π-π* transition, whereas for the deprotonated form, S1 is a completely charge-separation state and is responsible for the photoinduced electron transfer (PET) process. The PET process from anthracene to the pyrimidine moiety leads to the fluorescence quenching.

  13. 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

  14. 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

  15. Reproducibility of expired breath hydrogen levels in the neonate: a comparison of two methods for sample collection.

    PubMed

    Broadbent, R; Robb, T A; Davidson, G P

    1983-02-07

    We have compared a nasopharyngeal catheter method for breath sampling and a valved collection device. Sample quality was assessed by simultaneous oxygen measurement and reproducibility was checked by the analysis of 50 pairs of samples from four premature neonates. Both collection methods produced samples of highly variable quality suggesting a variable mixture of alveolar and non-alveolar air as well as differences in expired oxygen levels between babies. The mean oxygen levels were similar for both sampling techniques. Linear regression analysis of paired hydrogen results showed a highly significant correlation coefficient r = 0.73. This was improved markedly to r = 0.94 by normalization of hydrogen values based on observed oxygen levels, and so supports the earlier article by Robb and Davidson [1]. All breath hydrogen analyses require a measure of sample quality. Reproducible results and meaningful changes in hydrogen concentration in breath samples can only be achieved by correction according to sample quality. Correction to a common oxygen value should allow quantitative comparisons between patients. Samples were best collected from neonates by the nasopharyngeal catheter method, which least disturbed the patient, allowed multiple sample collection and gave lower oxygen and higher hydrogen values where large differences between pairs occurred.

  16. 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.

  17. Fluoride and Water (For Parents)

    MedlinePlus

    ... Your 1- to 2-Year-Old Fluoride and Water KidsHealth > For Parents > Fluoride and Water A A ... to 19-year-olds continue Fluoride and the Water Supply For more than 60 years, water fluoridation ...

  18. Fluoride and Water (For Parents)

    MedlinePlus

    ... Your 1- to 2-Year-Old 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 ...

  19. Biomonitoring Equivalents for interpretation of urinary fluoride.

    PubMed

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

    2015-06-01

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

  20. 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.

  1. 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

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

    PubMed

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

    2013-07-01

    A randomized clinical trial was performed in schoolchildren (6-7 yrs) to evaluate fluoride concentration in interproximal fluid after the placement of 3 different sealants. The sample consisted of 2,776 children randomly divided: 926 in the high-viscosity Glass-ionomer Cement group (GIC group), 923 in the fluoride Resin-based group (fluoride-RB group), and 927 in the no-fluoride Resin-based group (RB group). In total, 2,640 children completed the trial. Sealants were applied following manufacturer's instructions. Interproximal fluid samples were collected at baseline and 2, 7, and 21 days after application of sealants, by insertion of a standardized paperpoint into the interproximal mesial space of the sealed tooth for 15 seconds. Fluoride concentration was evaluated by means of a fluoride ion-selective electrode. At 2 days after sealant application, fluoride concentration was significantly higher in GIC and fluoride-RB groups compared with that in the RB group (p < .01). Mean fluoride concentrations after 7 days were 2.54 (SE 0.68) ppm, 0.85 (SE 0.26) ppm, and 0.53 (SE 0.11) ppm for the three groups, respectively. After 21 days, fluoride concentration in the GIC group remained higher than that in the other two groups. High-viscosity GIC sealants increased the fluoride concentrations in interproximal fluid more than did a Resin-based sealant containing fluoride.

  3. 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.

  4. Manufacture and properties of fluoride cement

    NASA Astrophysics Data System (ADS)

    Malata-Chirwa, Charles David

    This research work aimed at characterising composition, hydration and physical properties of fluoride cement, by studying samples of the cement obtained from Malawi, and comparing them to ordinary Portland cement. By confirming the suitable characteristics of fluoride cement through this work, the results of the research work provide a good basis for the wider adoption of fluoride cement as an alternative to ordinary Portland cement, especially in developing economies. Numerous accounts have been cited regarding the production and use of fluoride cement. Since there have not been conclusive agreement as to its properties, this study was limited to the theories of successful incorporation of fluoride compounds in the manufacture of fluoride cement. Hence, the properties and characteristics reported in this study relate to the cement currently manufactured in Malawi, and, on a comparative basis only, to that manufactured in other parts of the world. Samples of the fluoride cement used in the study were obtained by synthetic manufacture of the cement using common raw materials for the manufacture of fluoride cement that is limestone, silica sand, and fluorspar. These samples were subjected to several comparative tests used to characterise cements including examination under x-ray diffractometer, scanning electron microscopy and tests for setting time and compressive strength. Under similar laboratory conditions, it was possible to prove that fluoride cement hardens more rapidly than ordinary Portland cement. Also observed during the experimental work is that fluoride cement develops higher compressive strengths than ordinary Portland cement. The hardening and setting times are significantly different between the two cements. Also the nature of the hydration products, that is the microstructural development is significantly different in the two cements. The differences brought about between the two cements are because of the presence of fluorine during the clinkering

  5. How Does Fluoride Work?

    MedlinePlus

    ... Work? A A A There's fluoride in your toothpaste and even in your water. But how does ... enamel from plaque and sugars. By using fluoride toothpaste, for instance, everyone can enjoy some cavity protection. ...

  6. 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.

  7. An exclusive fluoride receptor: Fluoride-induced proton transfer to a quinoline-based thiourea

    PubMed Central

    Basaran, Ismet; Khansari, Maryam Emami; Pramanik, Avijit; Wong, Bryan M.; Hossain, Alamgir

    2014-01-01

    A new quinoline-based tripodal thiourea has been synthesized, which exclusively binds fluoride anion in DMSO, showing no affinity for other anions including, chloride, bromide, iodide, perchlorate, nitrate and hydrogen sulfate. As investigated by 1H NMR, the receptor forms both 1:1 and 1:2 complex yielding the binding constants of 2.32(3) (in log β1) and 4.39(4) (in log β2), respectively; where quinoline groups are protonated by the fluoride-induced proton transfer from the solution to the host molecule. The 1:2 binding is due to the interactions of one fluoride with NH binding sites of urea sites and another fluoride with secondary +NH binding sites within the tripodal pocket. The formation of both 1:1 and 1:2 complexes has been confirmed by the theoretical calculations based on density functional theory (DFT). PMID:24753636

  8. 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.

  9. 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

  10. 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.

  11. Evaluation and calibration of a pulsed neutron method for total hydrogen determination in mineral and concrete samples

    NASA Astrophysics Data System (ADS)

    Bennun, L.; Santibañez, M.; Gomez, J.; Santisteban, J. R.

    2011-11-01

    We studied the feasibility of a nondestructive method to determine hydrogen concentrations in concrete and mineral samples. The amount of total hydrogen in the sample is directly related to the proportion of water included in the paste preparation; and also considers all subsequent processes which can add or remove hydrogen in a real sample (like rain, evaporation, etc.). The hydrogen proportion is a critical variable in the curing concrete process; its excess or deficiency impacts negatively in the quality of the final product. The proposed technique is based on a pulsed neutron source and the technical support of the time of flight, which allow discriminating epithermal neutrons interacting with hydrogen (inelastic scattering) from the elastic and quasi-isotropic scattering produced by other kinds of atoms. The method was externally calibrated in limestone rocks fragments (CaCO3-main material used in cement fabrication) and in steel, allowing an easy retrieval of the required information. The technique's simplicity may facilitate the development of a mobile measuring device in order to make determinations "in situ." In this paper, we describe the foundations of the proposed method and various analysis results.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Fluorides and non-fluoride remineralization systems.

    PubMed

    Amaechi, Bennett T; van Loveren, Cor

    2013-01-01

    Caries develops when the equilibrium between de- and remineralization is unbalanced favoring demineralization. De- and remineralization occur depending on the degree of saturation of the interstitial fluids with respect to the tooth mineral. This equilibrium is positively influenced when fluoride, calcium and phosphate ions are added favoring remineralization. In addition, when fluoride is present, it will be incorporated into the newly formed mineral which is then less soluble. Toothpastes may contain fluoride and calcium ions separately or together in various compounds (remineralization systems) and may therefore reduce demineralization and promote remineralization. Formulating all these compounds in one paste may be challenging due to possible premature calcium-fluoride interactions and the low solubility of CaF2. There is a large amount of clinical evidence supporting the potent caries preventive effect of fluoride toothpastes indisputably. The amount of clinical evidence of the effectiveness of the other remineralization systems is far less convincing. Evidence is lacking for head to head comparisons of the various remineralization systems.

  17. 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.

  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.

  19. Ab initio molecular dynamics of hydrogen dissociation on metal surfaces using neural networks and novelty sampling.

    PubMed

    Ludwig, Jeffery; Vlachos, Dionisios G

    2007-10-21

    We outline a hybrid multiscale approach for the construction of ab initio potential energy surfaces (PESs) useful for performing six-dimensional (6D) classical or quantum mechanical molecular dynamics (MD) simulations of diatomic molecules reacting at single crystal surfaces. The algorithm implements concepts from the corrugation reduction procedure, which reduces energetic variation in the PES, and uses neural networks for interpolation of smoothed ab initio data. A novelty sampling scheme is implemented and used to identify configurations that are most likely to be predicted inaccurately by the neural network. This hybrid multiscale approach, which couples PES construction at the electronic structure level to MD simulations at the atomistic scale, reduces the number of density functional theory (DFT) calculations needed to specify an accurate PES. Due to the iterative nature of the novelty sampling algorithm, it is possible to obtain a quantitative measure of the convergence of the PES with respect to the number of ab initio calculations used to train the neural network. We demonstrate the algorithm by first applying it to two analytic potentials, which model the H2/Pt(111) and H2/Cu(111) systems. These potentials are of the corrugated London-Eyring-Polanyi-Sato form, which are based on DFT calculations, but are not globally accurate. After demonstrating the convergence of the PES using these simple potentials, we use DFT calculations directly and obtain converged semiclassical trajectories for the H2/Pt(111) system at the PW91/generalized gradient approximation level. We obtain a converged PES for a 6D hydrogen-surface dissociation reaction using novelty sampling coupled directly to DFT. These results, in excellent agreement with experiments and previous theoretical work, are compared to previous simulations in order to explore the sensitivity of the PES (and therefore MD) to the choice of exchange and correlation functional. Despite having a lower energetic

  20. Calcium fluoride window mounting

    NASA Astrophysics Data System (ADS)

    Berger, D. Douglas

    1982-10-01

    A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.

  1. 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.

  2. Indium fluoride glass fibers

    NASA Astrophysics Data System (ADS)

    Saad, Mohammed

    2012-03-01

    Fluoride glasses are the only material that transmit light from ultraviolet to mid-infrared and can be drawn into industrial optical fibers. The mechanical and optical properties of new indium fluoride glass fibers have been investigated. Multimode fiber 190 microns, has very high mechanical strength greater than 100 kpsi and optical loss as low as 45 dB/km between 2 and 4 microns. Unlike chalcogenide glass fibers, indium fluoride fiber has a wide transmission window from 0.3 to 5.5 microns without any absorption peak. Indium fluoride glass fibers are the technology of choice for all application requiring transmission up to 5 micron such as infrared contour measure (IRCM) and chemical sensing. Furthermore, Indium fluoride glasses have low phonon energy and can be heavily doped and co-doped whit rare-earth elements. Therefore they are very promising candidates for infrared fiber lasers.

  3. 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.

  4. 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.

  5. 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.

  6. Probability of foliar injury for Acer sp. based on foliar fluoride concentrations.

    PubMed

    McDonough, Andrew M; Dixon, Murray J; Terry, Debbie T; Todd, Aaron K; Luciani, Michael A; Williamson, Michele L; Roszak, Danuta S; Farias, Kim A

    2016-12-01

    Fluoride is considered one of the most phytotoxic elements to plants, and indicative fluoride injury has been associated over a wide range of foliar fluoride concentrations. The aim of this study was to determine the probability of indicative foliar fluoride injury based on Acer sp. foliar fluoride concentrations using a logistic regression model. Foliage from Acer nedundo, Acer saccharinum, Acer saccharum and Acer platanoides was collected along a distance gradient from three separate brick manufacturing facilities in southern Ontario as part of a long-term monitoring programme between 1995 and 2014. Hydrogen fluoride is the major emission source associated with the manufacturing facilities resulting with highly elevated foliar fluoride close to the facilities and decreasing with distance. Consistent with other studies, indicative fluoride injury was observed over a wide range of foliar concentrations (9.9-480.0 μg F(-) g(-1)). The logistic regression model was statistically significant for the Acer sp. group, A. negundo and A. saccharinum; consequently, A. negundo being the most sensitive species among the group. In addition, A. saccharum and A. platanoides were not statistically significant within the model. We are unaware of published foliar fluoride values for Acer sp. within Canada, and this research provides policy maker and scientist with probabilities of indicative foliar injury for common urban Acer sp. trees that can help guide decisions about emissions controls. Further research should focus on mechanisms driving indicative fluoride injury over wide ranging foliar fluoride concentrations and help determine foliar fluoride thresholds for damage.

  7. 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.

  8. Dietary fluoride supplements for children--the role of the physician.

    PubMed

    Alley, J W; Alderman, E J; Levy, S M; Kuthy, R A

    1989-09-01

    1. All children should receive one form of systemic fluoride and appropriate forms of topical fluoride. 2. If a child is not receiving optimally fluoridated water, the dentist or physician should prescribe dietary fluoride supplements (tablets or drops). 3. The correct dosage must be determined based on patient age and fluoride content of the patient's main water source(s). 4. Special attention is necessary concerning fluoride intake for children breast feeding or consuming infant formula. 5. To arrive at the correct fluoride dose, these steps should be followed: A. Always have a sample of the main drinking water source (usually home water) analyzed for the fluoride content before prescribing a fluoride supplement, if you do not have other specific knowledge of water fluoride content. The Medical College of Georgia (Department of Oral Biology - Dr. Whitford) provides water fluoride assay services. B. When the fluoride content of the water has been determined, the fluoride level and the child's age should be matched on Table 1 to arrive at the correct supplement dose. 6. Dr. Alderman, Director of the Office of Dental Health, Division of Public Health, Georgia Department of Human Resources, can provide lists of communities in Georgia that are optimally fluoridated.

  9. 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

  10. 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.

  11. Novel fluorogenic probe for fluoride ion based on the fluoride-induced cleavage of tert-butyldimethylsilyl ether

    NASA Astrophysics Data System (ADS)

    Yang, Xiao-Feng

    2007-06-01

    A highly sensitive and selective fluorogenic probe for fluoride ion, 4-methylumbelliferyl tert-butyldimethylsilyl ether (4-MUTBS), was designed and synthesized. 4-MUTBS was a weakly fluorescent compound and was synthesized via the one-step reaction of 4-MU with tert-butyldimethylsilyl chloride. Upon incubation with fluoride ion in acetone-water solution (7:3, v/v), the Si-O bond of 4-MUTBS was cleaved and highly fluorescent 4-methylumbelliferone (4-MU) was released, hence leading to the fluorescence increase of the reaction solution. The fluorescence increase is linearly with fluoride concentration in the range 50-8000 nmol l -1 with a detection limit of 19 nmol l -1 (3 σ). Because of the high affinity of silicon toward fluoride ion, the proposed probe shows excellent selectivity toward fluoride ion over other anions. The method has been successfully applied to the fluoride determination in toothpaste and tap water samples.

  12. 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.

  13. Fluoride analysis of human milk in remote areas of Thailand.

    PubMed

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

    2000-09-01

    The objective of this study was to measure the fluoride content in human milk collected from mothers living in remote areas of Thailand and to correlate it with fluoride concentrations in drinking water and water for domestic use. Four to five ml of breast milk were sampled from mothers living in villages where schools under the jurisdiction of the Department of Border Patrol Police were located. The schools were sampled by Multiple Stratified Cluster Random Sampling. Fluoride was determined by microdiffusion method. Statistical analysis were made by ANOVA and LSD test. Correlation between fluoride content in milk and water was assessed by Kendall's tau-b. The mean fluoride concentration in breast milk was 0.017+/-0.02 ppm. There was no difference in breast milk fluoride concentration between regions (p=0.6). No correlation was found between breast milk fluoride content and fluoride concentrations in either drinking water or water for domestic use (r(tau) = -0.09, p = 0.32, r(tau) = -0.04, p = 0.65 respectively).

  14. Fluoride in diet

    MedlinePlus

    ... broken through the gums have changes in the enamel that covers the teeth. Faint white lines or ... regarding fluoride intake from reconstituted infant formula and enamel fluorosis: a report of the American Dental Association ...

  15. Other Fluoride Products

    MedlinePlus

    ... relatively infrequent, generally at 3 to 12–month intervals, fluoride gel poses little risk for dental fluorosis, ... many hours. Varnishes must be reapplied at regular intervals with at least 2 applications per year required ...

  16. How Does Fluoride Work?

    MedlinePlus

    ... Fluoride is a natural element found in the earth's crust as well as in water and air. ... Activity: Teeth What Are Dentures? Contact Us Print Resources Send to a Friend Permissions Guidelines About KidsHealth ...

  17. 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.

  18. 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.

  19. 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.

  20. Effect of fluoridated water on intelligence in 10-12-year-old school children

    PubMed Central

    Aravind, A.; Dhanya, R. S.; Narayan, Ajay; Sam, George; Adarsh, V. J.; Kiran, M.

    2016-01-01

    Aim: The aim of the present study was to evaluate the relationship of drinking water fluoride levels with children's intelligence quotient (IQ). Materials and Methods: Water was collected from initially identified endemic fluoride regions according to the geological research of Government of India. Fluoride concentration of the water was assessed by utilizing fluoride ion selective electrode, Orion 9609BN, and categorized on the basis of fluoride concentration into low, medium, and high-fluoride regions, i.e., Virajpet (low fluoride level < 1.2 ppm), Banavara (Medium fluoride level 1.2–2 ppm), and Mastihalli (High fluoride levels > 3 ppm). Government school from all three villages were selected randomly and IQ levels were assessed by using Raven's Standard Progressive Matrices. This test was conducted on each child in the study sample. Results: A significant inverse relationship was found between the fluoride concentration in drinking water and IQ (r value = −0.204; P < 0.000). It was observed that IQ level was negatively correlated with fluoride concentration in drinking water. Conclusion: It is concluded that IQ level was negatively correlated with fluoride level in drinking water. Factors that might affect children's IQ need to be considered, and it is necessary to devise solutions for preventing the harmful effects of excessive intake of fluoride ion to the body. PMID:28217543

  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. The future of water fluoridation and other systemic fluorides.

    PubMed

    Horowitz, H S

    1990-02-01

    School and community water fluoridation, salt fluoridation, and use of dietary fluoride supplements have abundant scientific support as effective caries-preventive methods. Because caries has declined greatly in many developed countries from use of topical fluorides, the absolute caries reduction will be considerably smaller when systemic fluoride methods are implemented now than it was 20 to 40 years ago. For countries with most of the population living in cities with communal water supplies, community fluoridation is the most logical approach from the standpoints of cost-effectiveness and total caries-preventive impact. In countries with a mostly rural population without central water supplies, salt fluoridation is more practical. Dietary fluoride supplements can be recommended only for regions where neither water fluoridation nor salt fluoridation is possible, or as a temporary measure. Although divergent views exist concerning the relative caries-preventive effects of pre-eruptive and post-eruptive fluoride administration, the effectiveness of systemic fluoride methods for preventing dental caries remains unchallenged. Persuasive scientific and public health arguments exist to justify implementing and sustaining their use. The future of these methods will be influenced by the findings of new clinical and epidemiological research. Social, political, economic, and educational factors will be of equal, if not greater, importance. Perceptions of the current severity of dental caries as a health problem and of risks associated with preventing the problem may affect the future uses of systemic fluorides more than will recommendations of scientists.

  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 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.

  6. Permeability and fluoride release of lining materials containing amine fluorides.

    PubMed

    Nordbö, H; Eriksen, H M

    1976-11-01

    The addition of amine fluorides to a copal recin (Copalite) and a chlorine caoutchouc varnish (Pergut S-40) has been studied. The permeability of Copalite films was only slightly increased whereas the excellent film-forming qualities of Pergut S-40 were destroyed by the addition of fluorides. A high fluoride release was found initially from test films of the materials but within 2-3 weeks a decrease to very low fluoride levels was observed.

  7. Fluorides in groundwater and its impact on health.

    PubMed

    Shailaja, K; Johnson, Mary Esther Cynthia

    2007-04-01

    Fluoride is a naturally occurring toxic mineral present in drinking water and causes yellowing of teeth, tooth problems etc. Fluorspar, Cryolite and Fluorapatite are the naturally occurring minerals, from which fluoride finds its path to groundwater through infiltration. In the present study two groundwater samples, Station I and Station II at Hyderabad megacity, the capital of Andhra Pradesh were investigated for one year from January 2001 to December 2001. The average fluoride values were 1.37 mg/l at Station I and 0.91 mg/l at Station II. The permissible limit given by BIS (1983) 0.6-1.2 mg/l and WHO (1984) 1.5 mg/l for fluoride in drinking water. The groundwaters at Station I exceeded the limit while at Station II it was within the limits. The study indicated that fluoride content of 0.5 mg/l is sufficient to cause yellowing of teeth and dental problems.

  8. 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.

  9. 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.

  10. 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.

  11. Safety Evaluation of Fluoride Content in Tea Infusions Consumed in the Azores-a Volcanic Region with Water Springs naturally Enriched in Fluoride.

    PubMed

    Linhares, Diana Paula Silva; Garcia, Patrícia Ventura; Amaral, Leslie; Ferreira, Teresa; Dos Santos Rodrigues, Armindo

    2017-01-24

    Tea is the second most commonly consumed beverage in the world. It is well recognized that the consumption of tea in high quantities can promote the development of fluorosis. The main objective of this study is to estimate the exposure to fluoride in the Azores through drinking tea prepared with water from different volcanic locations, by i) investigating the fluoride (F) content of various commercial brands of tea (Camellia sinensis) marketed in Azores and ii) comparing tea releasing rates of F according to brewing time, considering the fluoride concentration in the different types of water used for the infusion. Fluoride contents were determined by ion-selective electrode in 30 samples of drinking water from three different locations and in 450 samples of tea (black and green tea) from three different brands. Fluoride concentration in water ranged from 0.29 to 1.56 ppm (Porto Formoso and Sete Cidades village, respectively). Fluoride concentrations increased with brewing time, reaching the highest values in the Azorean black and green tea infusions. For all the studied brands, a negative correlation was found between tea fluoride contents and the pH of the water used to prepare the infusion. Fluoride concentration in infusions was significantly associated with the background fluoride concentration in drinking water. Since the fluoride concentration in groundwater varies accordingly to the geological conditions and tea consumption can contribute to fluoride intake, it is important to define the limits for tea consumption, particularly in fluoride-rich areas. Graphical Abstract Fluoride concentrations in black and green tea for 3 minutes of brewing time and, association between fluoride concentration and pH with brewing time.

  12. 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)

  13. 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.

  14. 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; ...

    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

  15. 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.

  16. 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

    2016-03-05

    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.

  17. 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.

  18. Hydrogen bonding. Part 25. The nature of the hydrogen bond in hydroxytropenylium chloride (tropone hydrochloride)

    NASA Astrophysics Data System (ADS)

    Harmon, Kenneth M.; Cross, Joan E.; Toccalino, Patricia L.

    1988-08-01

    Hydroxytropenylium iodide and bromide contain normal electrostatic OH⋯X - hydrogen bonds. Hydroxytropenylium chloride, however, contains a hydrogen bond intermediate between the normal electrostatic type and the very strong covalent type, similar to the hydrogen bonds found in choline fluoride or the Type I C∞v hydrogen dihalide ions. Infrared comparisons with compounds previously studied demonstrate that the hydroxytropenylium ion is a stronger hydrogen bond donor than either choline cation or protonated betaine cation, and suggest that hydroxytropenylium fluoride, if it can be prepared, should contain a three-center covalent hydrogen bond.

  19. [Fluoride content of table salt in Mexico City].

    PubMed

    Maupomé Carvantes, G; Jaramillo Lanchero, R D; Andrade Delgado, L C; Juárez Reyes, P L; López Pérez, R; Sánchez Navarro, W; Sánchez Pérez, L; Vásquez Obregón, V H

    1995-09-01

    The fluoride content of a sample of bags of salt for sale in Mexico City was measured in order to estimate the proportion of marketed salt that contained the quantity of fluoride set by the National Program for Prevention of Dental Caries through Consumption of Fluoridated Table Salt. The effectiveness of that program had never been evaluated. In March 1993, bags of salt were obtained from 70 of the 3544 neighborhoods that make up Mexico City. The stores were selected by simple random sampling. Salt was likewise purchased from 20% of the 146 supermarkets and self-service stores in the city, also selected as a random sample. Then, blind measurement was done of the fluoride content of 221 bags of salt. The true content of this element was often found to be below the amount called for by the government. In addition, it did not coincide with the quantity indicated on the package label, which is a violation of the law.

  20. 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.

  1. Small molecule fluoride toxicity agonists.

    PubMed

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

    2015-04-23

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

  2. Small Molecule Fluoride Toxicity Agonists

    PubMed Central

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

    2015-01-01

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

  3. Heavy Metal Fluoride Glasses.

    DTIC Science & Technology

    1987-04-01

    relatively low refractive Indices in the visible range of about 1.5-1.9 and fairly good chemical resistance towards water and weak acids. Their...particularly interesting to compare with crystalline fluorides (Refs. 25, 37) such as 7800 spinel-type Li2NiF4 ; 7700 rutile-type NiF2 ; 7500 perovskite-type

  4. 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)

  5. 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

  6. 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).

  7. 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.

  8. [Elimination of fluoride in urine during fluoridation of salt and drinking water].

    PubMed

    Wespi, H J; Bürgi, W

    1982-07-17

    From 552 ambulatory gynecological patients in different parts of Switzerland the urinary excretion of fluorine was measured. The patients were classified into 4 groups according to origin: (1) 84 women were from the Canton Basel-Stadt. In this city water has been fluoridated since 1962; (2) 139 women from Canton Glarus. In this area a pilot study was under way using table and baker's salt, to both of which 250 mg F/kg had been added; (3) 128 women from Canton Aargau who were using a low dose fluoridated salt (90 mg F/kg); (4) 201 patients from Cantons Aargau and Tessin respectively who were consuming neither fluoridated water or salt acted as controls. Quantitation of ionized fluorine in urine was performed by means of the fluoride ion sensitive electrode in afternoon urine samples, thus eliminating the influence of sex difference and diurnal rhythm in fluorine excretion. The molar urinary fluorine concentration was related to the corresponding urinary creatinine concentration and expressed as mumol F per mmol creatinine. The fluoridation of salt or water was considered ideal when the excretion factor amounted to 6.29 mumol X mmol-1. The most important finding was that the Glarus females excrete higher levels of fluorine than the patients from Basel, though the difference was no significant. The fluoridation of salt with 90 mg F/kg is followed by an increase of the excretion factor from 2.58 to 3.65 mumol X mmol-1. It could also be demonstrated that in Canton Glarus, where salt with higher fluorine content is used, the excretion coefficient remains below the level believed to be toxic in the long run. It is concluded that salt fluoridation with 250 gm F/kg is safe. Furthermore, the excretion of fluorine in the control group seems to confirm that fluorine is a trace element of ubiquitous occurrence even excreted in urine of individuals who deliberately avoid fluorine as an additive to table salt or water.

  9. Mapping of fluoride endemic areas and assessment of fluoride exposure.

    PubMed

    Viswanathan, Gopalan; Jaswanth, A; Gopalakrishnan, S; Siva ilango, S

    2009-02-15

    The prevalence of fluorosis is mainly due to the consumption of more fluoride through drinking water. It is necessary to find out the fluoride endemic areas to adopt remedial measures to the people on the risk of fluorosis. The objectives of this study are to estimate the fluoride exposure through drinking water from people of different age group and to elucidate the fluoride endemic areas through mapping. Assessment of fluoride exposure was achieved through the estimation fluoride level in drinking water using fluoride ion selective electrode method. Google earth and isopleth technique were used for mapping of fluoride endemic areas. From the study it was observed that Nilakottai block of Dindigul district in Tamil Nadu is highly fluoride endemic. About 88% of the villages in this block have fluoride level more than the prescribed permissible limit in drinking water. Exposure of fluoride among different age groups was calculated in this block, which comprises 32 villages. The maximum estimated exposure doses were 0.19 mg/kg/day for infants, 0.17 mg/kg/day for children and 0.10 mg/kg/day for adults. When compared with adequate intake of minimal safe level exposure dose of 0.01 mg/kg/day for infants and 0.05 mg/kg/day for other age groups, a health risk due to fluorosis to the people in Nilakottai block has become evident. From the results, the people in Nilakottai block are advised to consume drinking water with fluoride level less than 1 mg/l. It has been recommended to the government authorities to take serious steps to supply drinking water with low fluoride concern for the fluorosis affected villages.

  10. Level of Fluoride in Soil, Grain and Water in Jalgaon District, Maharashtra, India

    PubMed Central

    Dodamani, Arun Suresh; Vishwakarma, Prashanth; Jadhav, Harish Chaitram; Khairnar, Mahesh Ravindra; Deshmukh, Manjiri Abhay; Wadgave, Umesh

    2017-01-01

    Introduction Fluoride has an influence on both oral as well as systemic health. The major source of fluoride to body is through drinking water as well as through diet. Staple diet mainly depends on local environmental factors, food grains grown locally, its availability etc. Determination of fluoride level in these food grains is important. So, estimation of the amount of fluoride in grains and its relation to the sources of fluoride used for their cultivation viz., soil and water is important. Aim To estimate the relation of fluoride concentration in grains (Jowar) with respect to that of soil and water used for their cultivation. Materials and Methods Fifteen samples each of soil, water and grains were collected using standardized method from the same farm fields of randomly selected villages of Jalgaon district. Fluoride ion concentration was determined in laboratory using SPADNS technique. Mean difference in fluoride levels in between the groups were analyzed using ANOVA and Post-Hoc Tukey test. Linear regression method was applied to analyse the association of the fluoride content of grain with water and soil. Results There was a significant difference in between mean fluoride levels of soil and water (p<0.001) and in between soil and grain (p<0.001); however, difference in between mean fluoride levels of water and grain was found to be non significant (p=0.591). Also fluoride levels in all the three groups showed significant association with each other. Conclusion Fluoride level of soil, grains and water should be adjusted to an optimum level. Soil has positive correlation with respect to uptake of fluoride by Jowar grains. So, Jowar grains with optimum fluoride content should be made available in the commercial markets so that oral and general health can be benefitted. PMID:28384970

  11. 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.

  12. Fluoride in drinking water and human urine in Southern Haryana, India.

    PubMed

    Singh, Bhupinder; Gaur, Shalini; Garg, V K

    2007-06-01

    The objective of this study was to determine the fluoride content in drinking water and urine samples of adolescent males aged 11-16 years living in Southern Haryana, India. A total of 30 drinking water sources in the studied habitations were assessed for fluoride contamination. Fluoride was estimated in the urine of 400 male children randomly selected from these habitations. The fluoride concentration in drinking water and urine samples was determined using USEPA fluoride ion selective electrode method. The mean fluoride concentration in drinking water samples of Pataudi, Haily Mandi and Harsaru villages was 1.68+/-0.35, 3.22+/-1.18 and 1.78+/-0.12 mg/l, respectively. The mean urinary fluoride concentration was 2.26+/-0.024 mg/l at Pataudi, 2.48+/-0.77 mg/l at Haily Mandi and 2.43+/-0.84 mg/l at Harsaru village. The higher fluoride levels in the urine of children may be associated to higher fluoride levels in drinking water. The accuracy of measurements was assessed with known addition method in water and urine. Mean fluoride recovery was 98.0 and 99.1% in water and urine. The levels obtained were reproducible with in +/-3% error limit.

  13. Magnesium and fluoride distribution in human cementum with age.

    PubMed

    Tsuboi, S; Nakagaki, H; Takami, Y; Eba, H; Kirkham, J; Robinson, C

    2000-12-01

    Sixty-two human teeth, obtained from subjects aged 11 to 80 years, were used to determine the magnesium and fluoride concentration and distribution with age in human cementum. Transverse sections were prepared from the root region of teeth. Samples, each 30 microm thick, were abraded in sequence from the cementum surface and the cemento-dentine junction by an abrasive micro-sampling technique. Magnesium concentrations were lower in the cementum surface, and increased towards the cemento-dentine junction (CDJ), while fluoride concentrations were higher in cementum surfaces and tended to decrease towards CDJ. Fluoride distribution patterns were similar to that reported earlier while average fluoride concentration increased with age, however, either no change or decreasing tendencies were observed with magnesium.

  14. [Operational control of water fluoridation in Niterói, Rio de Janeiro, Brazil].

    PubMed

    Maia, Lucianne Cople; Valença, Ana Maria Gondim; Soares, Eduardo Lúcio; Cury, Jaime Aparecido

    2003-01-01

    The aim of this study was to evaluate the operational control of water fluoridation at the city water supply plant in Niterói, Rio de Janeiro, Brazil, from January to December 2000. The water treatment supervisor filled out a questionnaire on the control of water fluoridation. In addition, water samples were collected every two weeks for fluoride analysis before and after treatment. Samples were analyzed by an independent laboratory using an ion-specific electrode. According to the water treatment supervisor, the entire process for controlling fluoride concentration in the water was rigorous and complied with Brazilian guidelines, but according to testing, 96% of samples were inadequate in terms of risks/benefits of fluoride use from water. The information obtained from the plant supervisor and the test data were thus mutually inconsistent. Based on these data, an independent water fluoride concentration control program is needed to ensure the benefits of dental caries prevention for the population.

  15. Cerium fluoride nanoparticles protect cells against oxidative stress.

    PubMed

    Shcherbakov, Alexander B; Zholobak, Nadezhda M; Baranchikov, Alexander E; Ryabova, Anastasia V; Ivanov, Vladimir K

    2015-05-01

    A novel facile method of non-doped and fluorescent terbium-doped cerium fluoride stable aqueous sols synthesis is proposed. Intense green luminescence of CeF3:Tb nanoparticles can be used to visualize these nanoparticles' accumulation in cells using confocal laser scanning microscopy. Cerium fluoride nanoparticles are shown for the first time to protect both organic molecules and living cells from the oxidative action of hydrogen peroxide. Both non-doped and terbium-doped CeF3 nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus.

  16. 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)

  17. 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

  18. Trace and ultratrace analysis of purified water samples and hydrogen peroxide solutions for phosphorus by flow-injection method.

    PubMed

    Li, Zenhai; Oshima, Mitsuko; Sabarudin, Akhmad; Motomizu, Shoji

    2005-03-01

    A highly sensitive fluorescence-quenching method for the determination of phosphorus based on the formation of an ion associate between molybdophosphate and Rhodamine B (RB) was developed. A simple flow-injection system coupled with a fluorescence detector was used to measure the fluorescence intensity at 560 nm and 580 nm as an excitation and an emission wavelength, respectively. The calibration graph for phosphorus showed a good linearity in the range of (0 - 1) x 10(-7) M (1 M = 1 mol L(-1)), and a detection limit of 1 x 10(-9) M (S/N = 3). The proposed method was successfully applied to the determination of ultratrace amounts of phosphorus in ultrapurified and purified water samples, and to the determination of trace amounts of phosphorus in commercially-available hydrogen peroxide solutions with satisfactory results.

  19. 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.

  20. 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.

  1. Chemical Composition and Microhardness of Human Enamel Treated with Fluoridated Whintening Agents. A Study in Situ

    PubMed Central

    Petta, Thais de Mendonça; do Socorro Batista de Lima Gomes, Yasmin; Antunes Esteves, Renata; do Carmo Freitas Faial, Kelson; Souza D`Almeida Couto, Roberta; Martins Silva, Cecy

    2017-01-01

    Background: Dental whitening has been increasingly sought out to improve dental aesthetics, but may cause chemical and morphological changes in dental enamel surfaces. Objective: Assess in situ the effects of high-concentration hydrogen peroxide with and without fluoride on human dental enamel using the ion chromatography test (IC) and the Knoop hardness test (KHN). Material and Methods: Nineteen enamel specimens were prepared using third human molars. These specimens were fixed on molars of volunteers and were divided into groups: OP38-Opalescence Boost PF38%, PO37-Pola Office 37.5% and CO-Control group. For chemical analysis (n= 3), the dentin layer was removed, keeping only the enamel, which was subjected to acidic digestion by microwave radiation. It was necessary to perform sample dilutions for the elements fluorine (F), calcium (Ca) and phosphorus (P) for quantification using the IC test. The KHN (n= 5) was performed before and after the treatments. Five indentations were made, separated by 100 µm, for each specimen using a load of 25 gf for 5 seconds in the microdurometer. The data were analyzed using ANOVA with a 5% significance level. Results: The OP38 group had the largest concentrations of F, Ca and P ions. The PO37 group showed the lowest concentrations of F and Ca ions. The average KHN was not significantly different between the OP38 and PO37 groups. Conclusion: Enamel whitened with hydrogen peroxide containing fluoride had greater concentrations of F, Ca and P ions. The presence of fluoride in the whitening agent did not influence the enamel microhardness.

  2. 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

  3. Carbon, hydrogen and nitrogen in carbonaceous chondrites Abundances and isotopic compositions in bulk samples

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1985-01-01

    Whole-rock samples of 25 carbonaceous chondrites were analyzed for contents of C, H and N and delta C-13, delta D and delta N-15. Inhomogeneous distribution of these isotopes within individual meteorites is pronounced in several cases. Few systematic intermeteorite trends were observed; N data are suggestive of isotopic inhomogeneity in the early solar system. Several chondrites revealed unusual compositions which would repay further, more detailed study. The data are also useful for classification of carbonaceous chondrites; N abundance and isotopic compositions can differentiate existing taxonomic groups with close to 100 percent reliability; Al Rais and Renazzo clearly constitute a discrete 'grouplet', and there are hints that both CI and CM groups may each be divisible into two subgroups.

  4. 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.

  5. Mapping of fluoride endemic areas and correlation studies of fluoride with other quality parameters of drinking water of Veppanapalli block of Dharmapuri district in Tamil Nadu.

    PubMed

    Karthikeyan, G; Sundarraj, A Shunmuga; Elango, K P

    2003-10-01

    193 drinking water samples from water sources of 27 panchayats of Veppanapalli block of Dharmapuri district of Tamil Nadu were analysed for chemical quality parameters. Based on the fluoride content of the water sources, fluoride maps differentiating regions with high / low fluoride levels were prepared using Isopleth mapping technique. The interdependence among the important chemical quality parameters were assessed using correlation studies. The experimental results of the application of linear and multiple regression equations on the influence of hardness, alkalinity, total dissolved solids and pH on fluoride are discussed.

  6. 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.

  7. High density fluoride glass calorimeter

    NASA Astrophysics Data System (ADS)

    Xie, Q.; Scheltzbaum, J.; Akgun, U.

    2014-04-01

    The unprecedented radiation levels in current Large Hadron Collider runs, and plans to even increase the luminosity creates a need for new detector technologies to be investigated. Quartz plates to replace the plastic scintillators in current LHC calorimeters have been proposed in recent reports. Quartz based Cherenkov calorimeters can solve the radiation damage problem, however light production and transfer have proven to be challenging. This report summarizes the results from a computational study on the performance of a high-density glass calorimeter. High-density, scintillating, fluoride glass, CHG3, was used as the active material. This glass has been developed specifically for hadron collider experiments, and is known for fast response time, in addition to high light yield. Here, the details of a Geant4 model for a sampling calorimeter prototype with 20 layers, and its hadronic as well as electromagnetic performances are reported.

  8. Crystal structure of μ-fluorido-bis­{(η4-cyclo­octa­diene)[hexa­fluorido­anti­monato(V)]platinum(II)} hexa­fluorido­anti­monate(V) hydrogen fluoride 0.75-solvate1

    PubMed Central

    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 η4-bound cyclo­octa­diene (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 inter­actions although no H atoms could be localized for the disordered solvent mol­ecules. The resulting hydrogen-bonded network is three-dimensional. PMID:26870575

  9. Potential fluoride contamination in the drinking water of Marks Nagar, Unnao district, Uttar Pradesh, India.

    PubMed

    Jha, S K; Nayak, A K; Sharma, Y K

    2010-06-01

    This study was conducted in the summer season (May, 2007). The fluoride concentration along with other physico-chemical parameters in ground water samples was determined in Marks Nagar of Unnao district, Uttar Pradesh (India), since it is the only source of drinking water for the villagers. The fluoride concentration in the water varied from 0.8 to 13.9 mgl(-1) with a mean of 4.02 mgl(-1). The correlation analysis revealed that fluoride had a positive correlation with pH, CO(3), HCO(3), and sodium adsorption ratio (SAR), whereas a negative correlation with Ca and Mg was found. A soil profile was also dug in the area to assess depth-wise fluoride content in the soil. The soil samples and underneath calcium carbonate (CaCO(3)) concretion were analyzed for fluoride content. The percent of soluble fluoride to total fluoride in the soil varied from 25.15 to 4.76% down the soil profile. The soluble fluoride was found to decrease with the increase in the clay content in the soil. The total leachable fluoride in CaCO(3) concretions was found to be 6.08%. It was inferred from this study that the soil and underneath layer of CaCO(3) concretions may be the potential source of fluoride contamination in the shallow drinking water sources of the area.

  10. 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.

  11. [Water fluoridation and public health].

    PubMed

    Barak, Shlomo

    2003-11-01

    Fluoridation in Israel was first mooted in 1973 and finally incorporated into law in November 2002 obligating the Ministry of Health to add fluoride to the nation's water supply. Epidemiology studies in the USA have shown that the addition of one part per million of fluoride to the drinking water reduced the caries rate of children's teeth by 50% to 60% with no side effects. Both the WHO in 1994 and the American Surgeon General's report of 2000 declared that fluoridation of drinking water was the safest and most efficient way of preventing dental caries in all age groups and populations. Opposition to fluoridation has arisen from "antifluoridation" groups who object to the "pollution" of drinking water by the addition of chemicals and mass medication in violation of the "Patient's Rights" law and the Basic Law of Human Dignity and Liberty. A higher prevalence of hip fractures in elderly osteoporotic women and osteosarcoma in teenagers has been reported in areas where excess fluoride exists in the drinking water. However, none of the many independent professional committees reviewing the negative aspects of fluoridation have found any scientific evidence associating fluoridation with any ill-effects or health problems. In Israel, where dental treatment is not included in the basket of Health Services, fluoridation is the most efficient and cheapest way of reducing dental disease, especially for the poorer members of the population.

  12. Effect of home-used water purifier on fluoride concentration of drinking water in southern Iran

    PubMed Central

    Jaafari-Ashkavandi, Zohreh; Kheirmand, Mehdi

    2013-01-01

    Background: Fluoride in drinking water plays a key role in dental health. Due to the increasing use of water-purifier, the effect of these devices on fluoride concentration of drinking water was evaluated. Materials and Methods: Drinking water samples were collected before and after passing through a home water-purifier, from four different water sources. The fluoride, calcium and magnesium concentration of the samples were measured using the quantitative spectrophotometery technique. Data were analyzed by the Wilcoxon test. P value < 0.1 was considered as significant. Results: The result showed that the concentration of fluoride was 0.05-0.61 ppm before purification and was removed completely afterward. Furthermore, other ions reduced significantly after treatment by the water purifier. Conclusion: This study revealed that this device decreases the fluoride content of water, an issue which should be considered in low and high-fluoridated water sources. PMID:24130584

  13. 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

  14. 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.

  15. Water fluoridation and osteoporotic fracture.

    PubMed

    Hillier, S; Inskip, H; Coggon, D; Cooper, C

    1996-09-01

    Osteoporotic fractures constitute a major public health problem. These fractures typically occur at the hip, spine and distal forearm. Their pathogenesis is heterogeneous, with contributions from both bone strength and trauma. Water fluoridation has been widely proposed for its dental health benefits, but concerns have been raised about the balance of skeletal risks and benefits of this measure. Fluoride has potent effects on bone cell function, bone structure and bone strength. These effects are mediated by the incorporation of fluoride ions in bone crystals to form fluoroapatite, and through an increase in osteoblast activity. It is believed that a minimum serum fluoride level of 100 ng/ml must be achieved before osteoblasts will be stimulated. Serum levels associated with drinking water fluoridated to 1 ppm are usually several times lower than this value, but may reach this threshold at concentrations of 4 ppm in the drinking water. Animal studies suggest no effect of low-level (0-3 ppm) fluoride intake on bone strength, but a possible decrease at higher levels. Sodium fluoride has been used to treat established osteoporosis for nearly 30 years. Recent trials of this agent, prescribed at high doses, have suggested that despite a marked increase in bone mineral density, there is no concomitant reduction in vertebral fracture incidence. Furthermore, the increase in bone density at the lumbar spine may be achieved at the expense of bone mineral in the peripheral cortical skeleton. As a consequence, high dose sodium fluoride (80 mg daily) is not currently used to treat osteoporosis. At lower doses, recent trials have suggested a beneficial effect on both bone density and fracture. The majority of epidemiological evidence regarding the effect of fluoridated drinking water on hip fracture incidence is based on ecological comparisons. Although one Finnish study suggested that hip fracture rates in a town with fluoridated water were lower than those in a matching town

  16. Destabilization effect of transition metal fluorides on sodium borohydride.

    PubMed

    Kalantzopoulos, Georgios N; Guzik, Matylda N; Deledda, Stefano; Heyn, Richard H; Muller, Jiri; Hauback, Bjørn C

    2014-10-14

    The effect of transition metal fluorides on the decomposition of NaBH4 has been investigated for NaBH4 ball milled with TiF3, MnF3 or FeF3. The compounds were examined by thermal programmed desorption with residual gas analysis, thermo gravimetric analysis and volumetric measurements using a Sieverts-type apparatus. The phase formation process during thermal decomposition was studied by in situ synchrotron radiation powder X-ray diffraction on the as-milled powders. NaBF4 was among the products in all mechano-chemical reactions. (11)B-NMR spectra analysis gave NaBF4 : NaBH4 ratios of 1 : 150 for Na-Ti, 1 : 40 for Na-Mn, and 1 : 10 for Na-Fe. Pure NaBH4 possessed a hydrogen release onset temperature of 430 °C. The hydrogen release in the NaBH4-MnF3 system began as low as 130 °C. FeF3 decreased the onset temperature to 161 °C and TiF3 to 200 °C. TiF3 reacted completely with NaBH4 below 320 °C. All the examined systems have negligible emissions of diborane species. H-sorption studies performed at selected temperatures above 300 °C exhibited relatively fast desorption kinetics. Partial hydrogen re-absorption was observed for the Na-Mn and Na-Fe samples.

  17. Effect of xylitol and fluoride on enamel erosion in vitro.

    PubMed

    Chunmuang, Siriwan; Jitpukdeebodintra, Suwanna; Chuenarrom, Chanya; Benjakul, Pojjanut

    2007-12-01

    This study aimed to determine the anti-erosive effects of xylitol, fluoride and a xylitol/fluoride combination used as an additive in an acidic drink or as mouthrinse after enamel was exposed to an acidic drink, in vitro. Human third molars were divided into 7 groups (A-G). Samples from groups A to D were immersed for 5 min in orange juice only (A), orange juice plus either 25% xylitol (B), F(-) 1 ppm (C) or a 25% xylitol/F(-) 1 ppm combination (D), respectively. Samples from groups E to G were immersed in orange juice for 5 min and then in either 40% xylitol (E), F(-) 227 ppm (F) or a 40% xylitol/F(-) 227 ppm combination (G), for 1 min respectively. This process was performed four times daily for 14 days. Mineral loss was determined from the lesion depth and surface hardness. Erosion depth progressively increased in all groups, except E, where erosion depth was significantly lower than group A. Surface microhardness progressively decreased in all groups, except E, where hardness was significantly higher than group A. This study demonstrated that addition of xylitol, fluoride or a xylitol/fluoride combination to an acidic drink or post-treatment with fluoride or a xylitol/fluoride combination could reduce, but not prevent, enamel erosion.

  18. Ultrastructural evaluation of enamel after dental bleaching associated with fluoride.

    PubMed

    Dominguez, John A; Bittencourt, Bruna; Michel, Milton; Sabino, Nilson; Gomes, João Carlos; Gomes, Osnara M M

    2012-08-01

    This study evaluated the effects on human enamel after two bleaching procedures: with a fluoridated bleaching agent and with topical fluoride application postbleaching. It used 43 enamel blocks (3 mm(2) ) that were ground flat (600-2,000 grit) and polished with polishing paste (one and one-fourth). Specimens were randomly divided into three groups according to the bleaching procedure: (1) control group, (2) hydrogen peroxide 35% (HPF) and topical application of fluoride 1.23%, and (3) HP 38% (OP) with fluoride in its composition. Bleaching agents were used according to the manufacturer's instructions. Three methodologies were used: nanoindentation, to observe surface hardness and elastic modulus; atomic force microscopy, to observe surface roughness (R(a) - R(z)); and scanning electron microscopy, to observe the enamel surface effects. Group OP had a decrease in the elastic modulus after bleaching, which was recovered at 14 days. An increased roughness (R(a); 32%) was observed on group HPF and had an increased erosion on enamel surface (67%). It was concluded that topical application of fluoride, after using the nonfluoridated whitening agent, increased the roughness values and erosion of enamel.

  19. Effects of flossing and rinsing with a fluoridated mouthwash after brushing with a fluoridated toothpaste on salivary fluoride clearance.

    PubMed

    Duckworth, R M; Horay, C; Huntington, E; Mehta, V

    2009-01-01

    The aims of this study were to test the hypothesis that flossing after brushing with a fluoridated toothpaste may lower salivary fluoride (F), and to evaluate the consequence of subsequent F mouthwash use. Twenty adults used 3 oral hygiene regimes in a randomised order: A, brushing with an NaF toothpaste; B, as A but followed by professional flossing; C, as B followed by rinsing with an NaF mouthwash. Saliva samples were collected up to 120 min after each regime and analysed for F. The mean area under the clearance curve value for regime C was statistically significantly greater than the corresponding values for A and B (p < 0.0001), which differed little. The regime that included the mouthwash may provide better anticaries protection.

  20. 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

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

    USGS Publications Warehouse

    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 δ2H 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 δ2H 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

  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. Tissue distributions of fluoride and its toxicity in the gills of a freshwater teleost, Cyprinus carpio.

    PubMed

    Cao, Jinling; Chen, Jianjie; Wang, Jundong; Wu, Xiangtian; Li, Yundong; Xie, Lingtian

    2013-04-15

    Fish take up fluoride directly from water and are susceptible to fluoride contamination of their environment. In this study, we examined the tissue distributions of fluoride and its toxicity in the gills of the common carp (Cyprinus carpio) chronically exposed to fluoride. Carp were exposed to a range of aqueous fluoride (35-124 mg/L) and sampled at 30, 60 and 90 days. The accumulation of fluoride in the tissues increased with the level and duration of exposure. Steady state was not achieved under the experimental conditions. The gills accumulated the highest levels of fluoride followed by the liver>brain>kidney>muscle>intestine. A dose-dependent inhibition was observed for the enzyme activities of Na(+)-K(+)-ATPase and Ca(2+)-ATPase in the gills after the fish were exposed for 90 days. Also, accumulation of fluoride was associated with the inhibition of superoxide dismutase (SOD) activities and a dose-dependent stimulation of malondialdehyde (MDA) levels in the gill tissues, suggesting that fluoride promoted oxidative stress in the fish. Microscopic examinations revealed injuries to gill tissues and chloride cells, with the severity of injury increasing with exposure concentration. These results suggest that chronic exposure to elevated concentrations of fluoride may induce toxicity in the common carp.

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

    PubMed

    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.

  6. Fluoride-based, low temperature solid electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Oh, Seajin; Otagawa, T.; Madou, M.

    Lanthanum fluoride electrolytes were tested to determine whether fluoride electrolytes can be used as fuel cell electrolytes at low temperatures. The planar-type fuel cell were operated in oxygen/hydrogen gases with nickel oxide/nickel as the anode and a perovskite structure oxide (La(0.6)Sr(0.4)CoO3) as the cathode. In order to reduce the fuel cell operating temperature while maintaining the highest possible current, various thin and thick film techniques were assessed. They include e-beam evaporation and dc plasma spray methods. Fuel cells incorporating plasma-sprayed LaF3 films yielded a short-circuit current density on the order of 0.4 mA/sq cm at 450 C, and the current density under an overpotential of 0.2V showed no sign of decay over 17 hours. In the co-ionic (fluoride and oxide ion) conduction mode, the lanthanum fluoride electrolyte based fuel cells could sustain current in oxygen/hydrogen gases.

  7. 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.

  8. Caries management with fluoride agents.

    PubMed

    Lam, Anty; Chu, C H

    2012-11-01

    Dental caries is the single most common, chronic oral disease of childhood. It is progressive and cumulative, and becomes more complex over time. The Surgeon General's Report on Oral Health revealed that more than 51 million school hours are lost each year as a result of dental problems. Contemporary caries management philosophy has changed from the traditional surgical approach to a medical model that emphasizes prevention. Among various strategies for caries prevention or reduction, fluoride therapy has been highly promoted. Various in-office and over-the-counter fluoride products are available for caries prevention. Dental professionals should identify and assess the caries risk level of patients and optimize the use of fluorides in caries management. Since multiple sources of fluoride exposure exist, a coordinated approach to fluoride delivery is essential.

  9. Coarse-Grained Conformational Sampling of Protein Structure Improves the Fit to Experimental Hydrogen-Exchange Data

    PubMed Central

    Devaurs, Didier; Antunes, Dinler A.; Papanastasiou, Malvina; Moll, Mark; Ricklin, Daniel; Lambris, John D.; Kavraki, Lydia E.

    2017-01-01

    Monitoring hydrogen/deuterium exchange (HDX) undergone by a protein in solution produces experimental data that translates into valuable information about the protein's structure. Data produced by HDX experiments is often interpreted using a crystal structure of the protein, when available. However, it has been shown that the correspondence between experimental HDX data and crystal structures is often not satisfactory. This creates difficulties when trying to perform a structural analysis of the HDX data. In this paper, we evaluate several strategies to obtain a conformation providing a good fit to the experimental HDX data, which is a premise of an accurate structural analysis. We show that performing molecular dynamics simulations can be inadequate to obtain such conformations, and we propose a novel methodology involving a coarse-grained conformational sampling approach instead. By extensively exploring the intrinsic flexibility of a protein with this approach, we produce a conformational ensemble from which we extract a single conformation providing a good fit to the experimental HDX data. We successfully demonstrate the applicability of our method to four small and medium-sized proteins. PMID:28344973

  10. Potential fluoride contamination in the drinking water of Naranji area, NorthWest Frontier Province, Pakistan.

    PubMed

    Shah, Mohammad Tahir; Danishwar, Shuhab

    2003-12-01

    The drinking water of Naranji village and surrounding areas of the NorthWest Frontier Province (NWFP), Pakistan, was analyzed for its fluoride content. The fluoride content of water samples from the springs in the Naranji village goes up to 13.52 mg kg(-1), which exceeds the permissible limit (1.5 mg kg(-1)) set by the World Health Organization (WHO). This study explores the source of fluoride contamination and attributes it to the alkaline rocks of the Ambela granitic complex and the Koga complex. The low-lying areas towards the south have a fluoride content within the permissible limit. The Naranji area therefore needs urgent remedial measures.

  11. 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.

  12. 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.

  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. Determination of Fluoride in Organic and Non-organic Wines.

    PubMed

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

    2016-12-27

    Fluorine is an element of great importance to human health, as it is considered to be an essential element. However, both a deficiency and an excess, it can cause various problems. It is for this reason that values have been established regarding the recommended daily intake (RDI) and acceptable daily intake (ADI). The largest source of incorporation of fluoride is water, but it can be found in other foods and beverages, such as vegetables, tea, and wine. The aim of the study was to establish the fluoride concentration in organic and non-organic wines from different appellations of origin of the Canary Islands and mainland Spain, in order to assess the contribution of fluoride and toxic risk. A total of 53 samples of red, white, and rosé wines, both organic and non-organic, from different appellations of origin were analyzed. They were analyzed by potentiometric determination with ion-selective electrode for fluoride using the method of standard addition. The wines analyzed are within the recommended limits set by the International Organisation of Vine and Wine. RDI is not exceeded for adults, taking into account the data provided by the Spanish Agency for Consumer Affairs, Food Safety and Nutrition on the average consumption of "table wines" in Spain. Fluoride intake from wine poses no risk to the health of adults. The fluoride concentration of organic and non-organic wines is within the range of 0.03 to 0.70 mg/L.

  15. 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…

  16. Synthesis and Crystallization Behavior of Fluoride Glasses

    DTIC Science & Technology

    1989-08-22

    metal fluoride glasses. Exploration of synthesis conditions for converting precursors to multicomponent oxide gels for conversion to heavy metal fluoride...glasses. Exploration of chemistries and conditions for converting multicomponent oxide gels to heavy metal fluoride glasses. Exploration of...chemical approaches to passivating the surfaces of heavy metal fluoride glasses. Exploration of the possibility of developing a computer model to describe

  17. Fluoride-induced chronic renal failure.

    PubMed

    Lantz, O; Jouvin, M H; De Vernejoul, M C; Druet, P

    1987-08-01

    Renal fluoride toxicity in human beings is difficult to assess in the literature. Although experimental studies and research on methoxyflurane toxicity have shown frank renal damage, observations of renal insufficiency related to chronic fluoride exposure are scarce. We report a case of fluoride intoxication related to potomania of Vichy water, a highly mineralized water containing 8.5 mg/L of fluoride. Features of fluoride osteosclerosis were prominent and end-stage renal failure was present. The young age of the patient, the long duration of high fluoride intake, and the absence of other cause of renal insufficiency suggest a causal relationship between fluoride intoxication and renal failure.

  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. Assessment of fluoride contaminations in groundwater of hard rock aquifers in Madurai district, Tamil Nadu (India)

    NASA Astrophysics Data System (ADS)

    Thivya, C.; Chidambaram, S.; Rao, M. S.; Thilagavathi, R.; Prasanna, M. V.; Manikandan, S.

    2015-07-01

    The fluoride contamination in drinking water is already gone to the alarming level and it needs the immediate involvement and attention of all people to solve this problem. Fluoride problem is higher in hard rock terrains in worldwide and Madurai is such type of hard rock region. Totally 54 samples were collected from the Madurai district of Tamilnadu with respect to lithology. The samples collected were analysed for major cations and anions using standard procedures. The higher concentration of fluoride is noted in the Charnockite rock types of northern part of the study area. 20 % of samples are below 0.5 ppm and 6 % of samples are above 1.5 ppm exceeding the permissible limit. The affinity between the pH and fluoride ions in groundwater suggests that dissolution of fluoride bearing minerals in groundwater. The higher concentration of fluoride ions are observed in the lower EC concentration. The isotopic study suggests that fluoride is geogenic in nature. In factor scores, fluoride is noted in association with pH which indicates the dissolution process.

  20. 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.

  1. Uranyl fluoride luminescence in acidic aqueous solutions

    SciTech Connect

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

    1996-08-01

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

  2. Fluoride release from new light-cured orthodontic bonding agents.

    PubMed

    McNeill, C J; Wiltshire, W A; Dawes, C; Lavelle, C L

    2001-10-01

    The purpose of this study was to compare the rates of fluoride release with time from 1 nonfluoridated and 3 fluoride-containing orthodontic bonding materials in distilled water and artificial saliva. Materials tested were Assure (Reliance Orthodontic Products, Itasca, Ill), Fuji Ortho LC (GC, Tokyo, Japan), Python (TP Orthodontics, LaPorte, Ind), and Transbond XT (3M Dental Products, Monrovia, Calif). Ten specimens of each material type were stored in distilled water, and 10 of each type were stored in artificial saliva at 37 degrees C. Fluoride release was measured with an ion-specific electrode. Readings were taken periodically for a total time period of 6 months. At day 1, Assure released the most fluoride into distilled water (66.2 microg/cm(2)) and into artificial saliva (65.8 microg/cm(2)), followed by Fuji Ortho LC (25.9 microg/cm(2); 18.8 microg/cm(2)), Python (6.3 microg/cm(2); 4.2 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The fluoride release rates were highest during the first days of testing, declining to lower but more stable levels. At the end of 6 months, Fuji Ortho LC released the most fluoride (3.8 microg/cm(2); 3.5 microg/cm(2)) followed by Assure (3.1 microg/cm(2); 2.8 microg/cm(2)), Python (2.6 microg/cm(2); 1.7 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The type of storage medium did not dramatically affect fluoride release. The second part of the study, undertaken after a year of sample storage, tested the 20 samples of Assure for a further 2-week period, after exposure to running and still distilled water. Although fluoride release rates declined with time, they were still higher than the 1.5 microg/cm(2) level that is referenced as inhibiting decalcification of enamel in a clinical environment. Release rates were similar in running and still water at all time points. Throughout the 6-month period, all 3 fluoride-containing materials had rates of fluoride release that could theoretically

  3. Spectral Diversity Crystalline Fluoride Lasers,

    DTIC Science & Technology

    1981-01-01

    2 4.-. i1.34 I R TUNABLE Table IX XeF Pumoe TM3 +: YLF :1 .Tm:YLF exhibits nearly ideal parameters for high energy operation aa3x10-20cm 2 ESAT 0cm e...host crystal, lithium yttrium fluoride, LiYF*4 ( YLF )" 1..0 Introductin Within the realm of crystalline laser materials,. the class of fluorides...on the host crystal, lithium yttrium fluoride, LiYF4 - often shortened as YLF . Tables I and 12 show the mechanical, thermal, and optical properties

  4. Strontium-90 fluoride data sheet

    SciTech Connect

    Fullam, H.T.

    1981-06-01

    This report is a compilation of available data and appropriate literature references on the properties of strontium-90 fluoride and nonradioactive strontium fluoride. The objective of the document is to compile in a single source pertinent data to assist potential users in the development, licensing, and use of /sup 90/SrF/sub 2/-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977.

  5. 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.

  6. 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.

  7. 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.

  8. Effects of fluoridated drinking water on dental caries in Australian adults.

    PubMed

    Slade, G D; Sanders, A E; Do, L; Roberts-Thomson, K; Spencer, A J

    2013-04-01

    Systematic reviews produce conflicting conclusions regarding dental caries-preventive effects of water fluoridation in adults. The authors investigated the relationship using data from the nationally representative 2004-2006 Australian National Survey of Adult Oral Health. Effects were compared between the pre-fluoridation cohort born before 1960 (n = 2,270) and the cohort born between 1960 and 1990 (n = 1,509), when widespread implementation of fluoridation increased population coverage from < 1% to 67%. Residential history questionnaires determined the percentage of each person's lifetime exposed to fluoridated water. Examiners recorded decayed, missing, and filled teeth (DMF-Teeth) and decayed and filled tooth surfaces (DF-Surfaces). Socio-demographic and preventive dental behaviors were included in multivariable least-squares regression models adjusted for potential confounding. In fully adjusted models, > 75% of lifetime exposure to fluoridation relative to < 25% of lifetime exposure was associated with 11% and 10% fewer DMF-Teeth in the pre-1960 (p < .0001) and 1960-1990 cohorts (p = .018), respectively. Corresponding reductions in DF-Surfaces were 30% (p < .001) and 21% (p < .001). Findings for intermediate fluoridation exposure suggested a dose-response relationship. Results were consistent in sensitivity analyses accounting for missing data. In this nationally representative sample of Australian adults, caries-preventive effects of water fluoridation were at least as great in adults born before widespread implementation of fluoridation as after widespread implementation of fluoridation.

  9. Salivary retention after application of fluoride gel using toothbrush or tray: a crossover trial.

    PubMed

    Ribeiro, Cecilia Claudia Costa; Lula, Estevam Carlos de Oliveira; Azevedo, Izabelle Maria Cabral de; Maia, Mariana de Figueiredo Lopes E; Lopes, Fernanda Ferreira

    2012-01-01

    Currently, there are no studies in the literature evaluating salivary fluoride retention after small amounts of fluoride gel are applied to children's teeth. Therefore, the objective of the present study was to compare salivary retention after gel application using a toothbrush or by traditional application with trays. In this crossover study, children with active caries (n = 10) were randomized into one of the following treatment groups: a) application of fluoride gel using a tray (control), or b) application of fluoride gel with a toothbrush (treatment). After a 7-day washout period, the treatments were inverted. Unstimulated saliva samples were collected at baseline and 0.5, 5, 15, 30, 60 and 120 minutes after acidulated phosphate fluoride (APF) gel application in order to analyze fluoride retention in saliva. The area under the curve (AUC) was also calculated. There were no differences in fluoride retention after application of small amounts of APF with a toothbrush compared to traditional gel application using trays at all time points studied, and no differences in AUC were observed (Student t-test, p > 0.05). These results suggest that application of fluoride gel in children using a toothbrush can be utilized as an option rather than traditional trays, since the same salivary retention of fluoride is obtained using a lower dose.

  10. Fluoride content of soft drinks, nectars, juices, juice drinks, concentrates, teas and infusions marketed in Portugal.

    PubMed

    Fojo, C; Figueira, M E; Almeida, C M M

    2013-01-01

    A potentiometric method using a fluoride combination ion-selective electrode was validated and used to analyse 183 samples, including soft drinks, juices, nectars, juice drinks, concentrates, teas and infusions marketed in Portugal. The fluoride levels were higher in extract-based soft drinks, juice drinks and juice, with fluoride values of 0.86 ± 0.35, 0.40 ± 0.24 and 0.37 ± 0.11 mg l⁻¹, respectively. The lowest fluoride concentration was found in infusion samples (0.12 ± 0.01 mg l⁻¹), followed by teas and carbonated soft drinks with fluoride concentrations of 0.16 ± 0.12 and 0.18 ± 0.07 mg l⁻¹, respectively. Nectars, concentrates and juice-based drinks had similar fluoride concentrations of 0.33 ± 0.16, 0.29 ± 0.12 and 0.25 ± 0.14 mg l⁻¹, respectively. The fluoride concentrations in all these samples would only contribute intakes below the acceptable daily intake (ADI = 0.05 mg kg⁻¹ body weight day⁻¹), indicating that, individually, these beverages cannot induce fluoride toxicity in the population group of children.

  11. 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.

  12. 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)

  13. 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

  14. 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.

  15. 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.

  16. Formation of phosphate-containing calcium fluoride at the expense of enamel, hydroxyapatite and fluorapatite.

    PubMed

    Christoffersen, J; Christoffersen, M R; Arends, J; Leonardsen, E S

    1995-01-01

    During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were investigated under well-defined conditions. pH and pF were monitored; calcium and phosphate concentrations were measured at selected times; the solid phases were examined by infra-red, X-ray diffraction and transmission electron microscopy. Precipitation of phosphate-containing calcium fluoride crystals, CaF2(P), can cause severe reduction in the calcium ion concentration and release of hydrogen ions from the precipitated phosphate. These reactions result in considerable dissolution of enamel, HAP and even of FAP. More of the added mineral dissolves with 50 mmol/l fluoride than with 10 mmol/l fluoride, mainly due to the greater reduction in calcium ion concentration. This work shows that phosphate-containing calcium fluoride is most likely an important compound to be considered in the caries process.

  17. Effect of Fluoride Gels on Microhardness and Surface Roughness of Bleached Enamel

    PubMed Central

    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. 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.

  20. Chronic fluoride toxicity: dental fluorosis.

    PubMed

    Denbesten, Pamela; Li, Wu

    2011-01-01

    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 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 dose-related decrease in cycles of ameloblast modulation from ruffle-ended 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 further

  1. Acute toxicity of ingested fluoride.

    PubMed

    Whitford, Gary Milton

    2011-01-01

    This chapter discusses the characteristics and treatment of acute fluoride toxicity as well as the most common sources of overexposure, the doses that cause acute toxicity, and factors that can influence the clinical outcome. Cases of serious systemic toxicity and fatalities due to acute exposures are now rare, but overexposures causing toxic signs and symptoms are not. The clinical course of systemic toxicity from ingested fluoride begins with gastric signs and symptoms, and can develop with alarming rapidity. Treatment involves minimizing absorption by administering a solution containing calcium, monitoring and managing plasma calcium and potassium concentrations, acid-base status, and supporting vital functions. Approximately 30,000 calls to US poison control centers concerning acute exposures in children are made each year, most of which involve temporary gastrointestinal effects, but others require medical treatment. The most common sources of acute overexposures today are dental products - particularly dentifrices because of their relatively high fluoride concentrations, pleasant flavors, and their presence in non-secure locations in most homes. For example, ingestion of only 1.8 ounces of a standard fluoridated dentifrice (900-1,100 mg/kg) by a 10-kg child delivers enough fluoride to reach the 'probably toxic dose' (5 mg/kg body weight). Factors that may influence the clinical course of an overexposure include the chemical compound (e.g. NaF, MFP, etc.), the age and acid-base status of the individual, and the elapsed time between exposure and the initiation of treatment. While fluoride has well-established beneficial dental effects and cases of serious toxicity are now rare, the potential for toxicity requires that fluoride-containing materials be handled and stored with the respect they deserve.

  2. 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

  3. 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

  4. 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.

  5. Selected mechanical properties of fluoride-releasing restorative materials.

    PubMed

    Iazzetti, G; Burgess, J O; Gardiner, D

    2001-01-01

    Mechanical properties, diametral tensile strength (DTS) and flexural strength (FS) of six fluoride releasing materials were measured and compared. The samples were prepared and tested according to ISO specifications. The materials included a glass ionomer (Fuji IX), a resin-modified glass ionomer (Photac-Fil), two compomers (F 2000; Dyract AP) and two composites (Solitaire; Tetric Ceram). The tests were performed after the materials were stored in distilled water (DTS) and phosphate buffered saline solution (FS) at 37 degrees C for 24 hours and one week. Fluoride-releasing composite resin had the highest flexural and diametral tensile strengths and were statistically stronger than compomers, followed by resin-modified glass ionomer and conventional glass ionomer. However, a notable exception to this general trend was Solitaire, a fluoride-releasing composite resin.

  6. 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.

  7. Taurine Ameliorates Renal Oxidative Damage and Thyroid Dysfunction in Rats Chronically Exposed to Fluoride.

    PubMed

    Adedara, Isaac A; Ojuade, Temini Jesu D; Olabiyi, Bolanle F; Idris, Umar F; Onibiyo, Esther M; Ajeigbe, Olufunke F; Farombi, Ebenezer O

    2017-02-01

    Excessive exposure to fluoride poses several detrimental effects to human health particularly the kidney which is a major organ involved in its elimination from the body. The influence of taurine on fluoride-induced renal toxicity was investigated in a co-exposure paradigm for 45 days using five groups of eight rats each. Group I rats received normal drinking water alone, group II rats were exposed to sodium fluoride (NaF) in drinking water at 15 mg/L alone, group III received taurine alone at a dose of 200 mg/kg group IV rats were co-administered with NaF and taurine (100 mg/kg), while group V rats were co-administered with NaF and taurine (200 mg/kg). Administration of taurine significantly reversed the fluoride-mediated decrease in absolute weight and organo-somatic index of the kidney in the exposed rats. Taurine significantly prevented fluoride-induced elevation in plasma urea and creatinine levels in the exposed rats. Moreover, taurine restored fluoride-mediated decrease in the circulatory concentrations of triiodothyronine, thyroxine, and the ratio of triiodothyronine to thyroxine. Taurine ameliorated fluoride-mediated decrease in renal antioxidant status by significantly enhancing the antioxidant enzyme activities as well as glutathione level in the exposed rats. Additionally, taurine inhibited fluoride-induced renal oxidative damage by markedly decreasing the hydrogen peroxide and malondialdehyde levels as well as improved the kidney architecture in the treated rats. Collectively, taurine protected against fluoride-induced renal toxicity via enhancement of thyroid gland function, renal antioxidant status, and histology in rats.

  8. Assessment of fluoride contamination in groundwater from Basara, Adilabad District, Telangana State, India

    NASA Astrophysics Data System (ADS)

    Narsimha, A.; Sudarshan, V.

    2016-10-01

    The major objective of this study was to locate the vulnerable areas in terms of fluoride contamination. A total of 34 groundwater samples were collected from major drinking water sources in rural areas of Basara, Telangana, and studied with reference to the distribution and hydrogeochemistry of fluoride. The geochemical trend of groundwater in the study area demonstrates that sodium is the dominant cation (Na+ > Ca2+ > Mg2+ > K+) and chloride is the dominant anion (Cl- > HCO3 - > SO4 2- > CO3 2- > NO3 - > F-). The fluoride concentration varied from 0.06 to 4.33 (1.13 ± 0.90) mg L-1 with the highest fluoride level at Karegaon village (4.33 mg L-1). Seven locations showed the presence of fluoride in excess of permissible levels.

  9. Retention of fluoride ions from aqueous solution using porous hydroxyapatite. Structure and conduction properties.

    PubMed

    Hammari, L E L; Laghzizil, A; Barboux, P; Lahlil, K; Saoiabi, A

    2004-10-18

    Synthetic porous calcium hydroxyapatite (noted p-HAp) treated with different fluoride concentrations at room temperature in the presence of carbonate, sodium chloride and phosphate-rich media was investigated. The fluoridation rate of the porous calcium hydroxyapatite was 89% using 1 mol/L [F(-)] solution compared with 30% for crystalline hydroxyapatite (c-HAp). The high specific surface area of p-HAp (235 m(2)g(-1)) compared with c-HAp sample (47 m(2)g(-1)) has an important effect on the removal of fluoride ions from aqueous solution, when p-HAp was treated with high fluoride concentration to produce calcium fluorohydroxyapatite materials. Fluoride adsorption on porous hydroxyapatites (p-HAp) modified their structural and conduction properties.

  10. Brushing abrasion of eroded bovine enamel pretreated with topical fluorides.

    PubMed

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

    2006-01-01

    Topical fluorides have been proposed for the prevention of erosive dental wear. This study evaluated the in vitro effect of a single professional application of 4% titanium tetrafluoride (TiF4), 1% amine fluoride (AmF) and 0.1% difluorosilane varnish (FV) in preventing wear due to combined erosion and brushing abrasion. One hundred and eight bovine enamel samples were used. Control groups were not pretreated with any product (C), pretreated with a fluoride-free varnish (FV-bl) or pretreated with fluoride varnish and subsequently submitted to varnish removal (FV-r). Wear was modeled by submitting the fluoride-treated and control groups to 3 cycles of the following regimens: erosion/remineralization (er/remin), abrasion/remineralization (abr/remin) or erosion/abrasion/remineralization (er/abr/remin). Erosion was simulated by immersion of the samples for 10 min in citric acid 50 mM (pH 3). Abrasion was carried out for 1 min (200 strokes, load 150 g) in a wear device. Remineralization (2 h artificial saliva) took place between the cycles. Two-way ANOVA showed that there was a significant interaction (pfluoride treatments and the wear regimens. Under er/remin a significant wear protective effect was found for the FV, FV-r and FV-bl groups. Abr/remin resulted in some enamel loss for the TiF4 and AmF groups, but the amounts lost were not statistically significant (p=0.185 and p=1.000, respectively). Under er/abr/remin all products showed a significant protective effect, except for TiF4. It was concluded that FV and AmF protected bovine enamel against erosion followed by brushing abrasion in vitro.

  11. [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.

  12. 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.

  13. Removal of fluoride ions from water by adsorption onto carbonaceous materials produced from coffee grounds.

    PubMed

    Ogata, Fumihiko; Tominaga, Hisato; Yabutani, Hitoshi; Kawasaki, Naohito

    2011-01-01

    Carbonaceous material for the removal of fluoride ions from water was prepared from coffee grounds (CGs) by calcination and subsequent HCl treatment. The characteristics of the CGs, including the surface area, mean pore diameter, pore volume, and surface functional groups were determined, and the morphological characteristics were evaluated using scanning electron microscopy. The adsorption isotherms, saturated amount of fluoride ions adsorbed, and the effect of contact time and temperature on the adsorption of fluoride ions were investigated for a sample of tap water. The specific surface area of CG calcined at 600° (CG600) was larger than that of CGs calcined at 400, 800, and 1000°. Phenolic, lactonic, and carboxyl groups were detected on the CG600 surface. The adsorption capacity of the carbonized CGs for fluoride was ranked in the order CG400 < CG1000 < CG800 < CG600 (where the numeral indicates the carbonization temperature), whereas virgin CG and CG600-NAT (not treated with hydrochloric acid solution) did not exhibit any adsorption ability for fluoride ions. The amount of fluoride ions adsorbed onto CG600 increased with increasing temperature and was consistent with chemical adsorption. The mechanism of adsorption of fluoride ions onto CG600 proceeded via ion exchange with chloride ions (1:1) present on the surface of CG600. The adsorption isotherms were fitted to the Freundlich and Langmuir equations. Moreover, CG600 showed an acceptable adsorption capacity for fluoride ions present in tap water.

  14. 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.

  15. 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.

  16. 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.

  17. Microcratering in Polyvinylidene Fluoride

    NASA Astrophysics Data System (ADS)

    Shu, Anthony John

    Dust is defined as macroparticles as small as a few molecules up to several micrometers in diameter. In the context of space exploration, it was originally seen only as a technical obstacle to applications; dust can damage instrument surfaces, coat mating surfaces preventing proper seals, and impair or obstruct measurements. Because of the ubiquity of dust in the solar system and its role in the origin of planets and other bodies, the study of dust and related phenomena has evolved to a scientific subdiscipline which can provide us insight into the origins and evolution of our solar system. In order to facilitate this, a hypervelocity dust accelerator has been built at the University of Colorado at Boulder and is being used to probe impact phenomena, dust mitigation techniques, dust detection techniques, and more. One such dust detector is a Polyvinylidene Fluoride (PVDF) dust detector. The PVDF dust detector is very lightweight and consumes little power. Due to these properties, PVDF detectors can potentially be used on any spacecraft to gain information on the local dust environment. It is not fully understood how this PVDF dust detector signal is generated, so at present can only be used as a dust counter. In this thesis I discuss the importance of the study of dust phenomena, describe the accelerator experiment, and describe a study conducted to determine the underlying physical principles of PVDF dust detectors. This included measuring crater size scaling laws, measuring the detailed shape of craters, and applying this data to simulations of the signals being generated by PVDF detectors.

  18. Fluoride Glass Fibres For Telecommunications

    NASA Astrophysics Data System (ADS)

    Maze, Gwenael; Cardin, Vincent; Poulain, Marcel

    1983-09-01

    Zirconium fluoride glasses are the best known and the most stable beryllium-free glasses. They offer numerous potential uses for I.R.-transmitting fibres and ultra-long repeaterless optical wave-guides. Various problems arise in the manufacturing of fluoride glass fibres, essentially because of the steep viscosity profile and the devitrification phenomena. This paper discusses the processes for manufacturing step-index preforms and for drawing fibres. Optical quality preforms have been obtained and fibres have been drawn over more than 1 km. A spectral loss measurement system has been constructed using fluoride glass optical components. Several curves showing the optical attenuation versus wavelength are presented and discussed. These fibres are now available for optical transmission in infra-red systems.

  19. 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…

  20. 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)

  1. 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.

  2. The effect of point-of-use water conditioning systems on community fluoridated water.

    PubMed

    Brown, M D; Aaron, G

    1991-01-01

    The purpose of this investigation was to determine the effect of several point-of-use water conditioning systems on the fluoride concentration in community fluoridated water. Point-of-use water conditioning systems attach at the sink to provide the user with protection from certain water contaminants. A sampling apparatus was constructed to allow collection of water samples before and after conditioning. The apparatus connected the following types of point-of-use water conditioning systems: a faucet water filter, a cellulose fiber filter, an activated carbon filter, a reverse osmosis system, and a distillation unit. These samples were tested by an independent laboratory using colorimetric determination of fluoride concentration. All point-of-use water conditioning systems tested caused a statistically significant reduction in fluoride (P less than .001). Of particular note were reductions in fluoride concentration by the activated carbon filter (81%), the reverse osmosis system (84%), and the distillation unit (99%). These reductions are clinically significant, and necessitate supplementation for optimal fluoride intake. Patients using these water conditioning systems should be advised to have their water tested, and to consider fluoride supplementation to ensure adequate benefit from this caries prevention method.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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.

  10. The determination of cobalt(II) at DME using catalytic hydrogen current technique in various water samples, agricultural materials and pharmaceuticals.

    PubMed

    Kanchi, S; Saraswathi, K; Venkatasubba Naidu, N

    2011-12-01

    Two novel and facile ligands ammonium piperidine dithiocarbamate (Amm Pip-DTC) and ammonium morpholine dithiocarbamate (Amm Mor-DTC) were synthesized for the development of rapid and cost effective catalytic hydrogen current technique to analyze cobalt(II) in the presence of NH(4)Cl-NH(4)OH at pH 7.8 and 8.4 with Amm Pip-DTC and Amm Mor-DTC. These ligands produce catalytic hydrogen currents with Co(II) at peak potentials -1.24 V and -1.44 V vs. SCE respectively. Quantitative experimental conditions are developed by studying effect of pH, supporting electrolyte (NH(4)Cl), ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the catalytic hydrogen current technique and compared it in terms of Student's t test and variance ratio f test with differential pulse polarographic (DPP) method. The developed technique was applied for the analysis of cobalt(II) in various water samples, agricultural materials and pharmaceuticals and the results obtained are in good agreement with the DPP data.

  11. 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.

  12. 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

  13. The influence of lifelong exposure to environmental fluoride on bone quality in humans

    NASA Astrophysics Data System (ADS)

    Chachra, Debbie

    The objective of this study was to determine if lifelong exposure to environmental sources of fluoride (including fluoridated water) had an effect on bone quality in humans. Ninety-two femoral heads were obtained from individuals undergoing total hip arthroplasty in regions with and without fluoridated water (Toronto and Montreal, respectively), so that the donors would have had a wide range of fluoride exposure. As the samples were obtained at surgery, the femoral heads were affected by osteoarthritis (75), osteoporosis (9) and other diseases. The fluoride content of cancellous bone was assessed by instrumental neutron activation analysis. A number of contributors to bone quality were assessed. The compressive and torsional mechanical properties were measured for cancellous cores excised from the centre of the femoral head. The architecture was assessed by image analysis of an x-ray of a 5 mm thick coronal section of the femoral head, as well as of histological sections taken from the superior (weightbearing) and the inferior (nonweightbearing) surface of the femoral head. The degree of mineralization was measured using backscattered electron imaging and microhardness, again at the superior and the inferior surface. Femoral heads from Toronto donors had a greater mean fluoride content than those from Montreal donors (1033 +/- 438 ppm vs. 643 +/- 220 ppm). However, the fluoride content of the Toronto donors ranged approximately twelve-fold (192--2264 ppm) and entirely contained the range of Montreal donors. Therefore, fluoridated water exposure is not the only determinant of fluoride content. The logarithm of the bone fluoride content increased with age. No substantive effect of fluoride, independent of age, was observed for the mechanical properties. Similarly, at the inferior surface, the architecture was affected by age but not by fluoride incorporation but the degree of mineralization was not affected by either. However, the degree of mineralization (measured

  14. Capillary electrophoresis with contactless conductivity detection for the quantification of fluoride in lithium ion battery electrolytes and in ionic liquids-A comparison to the results gained with a fluoride ion-selective electrode.

    PubMed

    Pyschik, Marcelina; Klein-Hitpaß, Marcel; Girod, Sabrina; Winter, Martin; Nowak, Sascha

    2017-02-01

    In this study, an optimized method using capillary electrophoresis (CE) with a direct contactless conductivity detector (C(4) D) for a new application field is presented for the quantification of fluoride in common used lithium ion battery (LIB) electrolyte using LiPF6 in organic carbonate solvents and in ionic liquids (ILs) after contacted to Li metal. The method development for finding the right buffer and the suitable CE conditions for the quantification of fluoride was investigated. The results of the concentration of fluoride in different LIB electrolyte samples were compared to the results from the ion-selective electrode (ISE). The relative standard deviations (RSDs) and recovery rates for fluoride were obtained with a very high accuracy in both methods. The results of the fluoride concentration in the LIB electrolytes were in very good agreement for both methods. In addition, the limit of detection (LOD) and limit of quantification (LOQ) values were determined for the CE method. The CE method has been applied also for the quantification of fluoride in ILs. In the fresh IL sample, the concentration of fluoride was under the LOD. Another sample of the IL mixed with Li metal has been investigated as well. It was possible to quantify the fluoride concentration in this sample.

  15. 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.

  16. 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)

  17. 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.

  18. 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)

  19. 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.

  20. Synchrotron radiation studies of beryllium fluoride glass

    NASA Astrophysics Data System (ADS)

    Williams, R. T.; Nagel, D. J.; Klein, P. H.; Weber, M. J.

    1980-07-01

    Beryllium fluoride glasses are possible materials for high power laser systems because of their low nonlinear refractive indexes. In addition the linear refractive index of BeF2 is extremely small, so that it may be of use in multilayer coatings for the ultraviolet. Reflectance of pure BeF2 glasses in the range 9 eV to 120 eV, as well as photoelectron spectra of the bulk glass in the valence band region were measured. Ultraviolet reflectivity and photoemission are useful measurements for indicating the ultimately achievable transmission edge since they sample very high densities of states, assumed intrinsic in nature. Both methods probe only the near surface region, so the hygroscopic nature of BeF2 presents a problem. An argon sputter etching gun was used to clean the samples in ultrahigh vacuum prior to measurement.

  1. Fissure seal or fluoride varnish?

    PubMed

    Deery, Christopher

    2016-09-01

    Data sourcesCochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry PlatformStudy selectionRandomised controlled trials (RCTs) with at least 12 months follow-up, in which fissure sealants, or fissure sealants together with fluoride varnishes, were compared with fluoride varnishes alone for preventing caries in occlusal surfaces of permanent teeth of children and adolescents.Data extraction and synthesisTwo reviewers independently screened search results, extracted data and assessed risk of bias of included studies. Studies were grouped and analysed on the basis of sealant material type (resin-based sealant and glass ionomer-based sealant, glass ionomer and resin-modified glass ionomer) and different follow-up periods. Odds ratio were calculated for caries or no caries on occlusal surfaces of permanent molar teeth. Mean differences were calculated for continuous outcomes and data. Evidence quality was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) methods.ResultsEight RCTs involving a total of 1747 children aged five to ten years of age were included. Three trials compared resin-based fissure sealant versus fluoride varnish. Results from two studies (358 children) after two years were combined. Sealants prevented more caries, pooled odds ratio (OR) = 0.69 (95%CI; 0.50 to 0.94). One trial with follow-up at four and nine years found that the caries-preventive benefit for sealants was maintained, with 26% of sealed teeth and 55.8% of varnished teeth having developed caries at nine years. Evidence for glass-ionomer sealants was of low quality. One split-mouth trial analysing 92 children at two-year follow-up found a significant difference in favour of resin-based fissure sealant together with fluoride varnish compared with fluoride varnish only (OR

  2. 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.

  3. 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.

  4. Metallic Hydrogen

    NASA Astrophysics Data System (ADS)

    Silvera, Isaac F.; Dias, Ranga; Noked, Ori; Salamat, Ashkan; Zaghoo, Mohamed

    2017-04-01

    One of the great challenges in condensed matter physics has been to produce metallic hydrogen (MH) in the laboratory. There are two approaches: solid molecular hydrogen can be compressed to high density at extreme pressures of order 5-6 megabars. The transition to MH should take place at low temperatures and is expected to occur as a structural first-order phase transition with dissociation of molecules into atoms, rather than the closing of a gap. A second approach is to produce dense molecular hydrogen at pressures of order 1-2 megabars and heat the sample. With increasing temperature, it was predicted that molecular hydrogen first melts and then dissociates to atomic metallic liquid hydrogen as a first-order phase transition. We have observed this liquid-liquid phase transition to metallic hydrogen, also called the plasma phase transition. In low-temperature studies, we have pressurized HD to over 3 megabars and observed two new phases. Molecular hydrogen has been pressurized to 4.2 megabars. A new phase transition has been observed at 3.55 megabars, but it is not yet metallic.

  5. 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.

  6. 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

  7. 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

  8. Hydrogen sulfide measurement by headspace-gas chromatography-mass spectrometry (HS-GC-MS): application to gaseous samples and gas dissolved in muscle.

    PubMed

    Varlet, Vincent; Giuliani, Nicole; Palmiere, Cristian; Maujean, Géraldine; Augsburger, Marc

    2015-01-01

    The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H(2)S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H(2)S measurement discussed in the literature was the absence of a specific H(2)S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D(2)S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D(2)S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N(2)O was chosen for use as an internal standard. This method allows precise measurements of H(2)S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the β-expectation tolerance interval is presented. Finally, this method was applied to quantify H(2)S in an actual case of H(2)S fatal intoxication.

  9. 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)...

  10. 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

  11. 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

  12. 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.

  13. Estimation of toothpaste fluoride intake in preschool children.

    PubMed

    do Nascimento, Helena Aguiar Ribeiro; Soares Ferreira, Jainara Maria; Granville-Garcia, Ana Flávia; de Brito Costa, Edja Maria Melo; Almeida Cavalcante, Ana Lúcia; Sampaio, Fábio Correia

    2013-01-01

    The objective of this study was to estimate the intake of toothpaste fluoride used by children aged 2 to 6 years (n=87) treated at a hospital of a medium-sized city (Campina Grande, PB) in the Northeastern region of Brazil. Data regarding sociodemographic characteristics of families and children's toothbrushing were collected from questionnaire-based interviews with parents/guardians, and the amount of fluoride used during toothbrushing was estimated using a precision scale for assessment of the risk of dental fluorosis, considering a cutoff value of 0.07 mgF/kg body weight/day. Fluoride content in the toothpastes was analyzed using a specific fluoride electrode. Data were analyzed using descriptive and inferential statistics using the chi-square and Fisher's exact tests (α=0.05). Considering the use of the derice, the risk of fluorosis in the children was 19.5%. There was significant association (p<0.05) between the risk of fluorosis, brushing frequency, type of derice and who performed the child's oral hygiene. It was concluded that a high percentage of children in the studied sample used toothpaste inappropriately and were at risk of developing dental fluorosis.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Fluoride contamination and fluorosis in rural community in the vicinity of a phosphate fertilizer factory in India.

    PubMed

    Pandey, J; Pandey, U

    2011-09-01

    We studied chronic fluoride intoxication in 10 villages of Udaipur receiving F emissions from phosphate fertilizer factories. Although fluoride remained below permissible limit in most of the drinking water samples, the incidence of fluorosis in adults as well as in children was surprisingly high. Khemli appeared to be the most affected village (with >48% cases) where, about 93% of 2 h air samples contained fluoride above 2.0 μg m(-3) and crops and vegetable F ranged from 27.5 to 143.4 μg g(-1). Concentrations of fluoride and inorganic P in urine showed asynchrony and were well linked with prevalence of fluorosis. The study indicated that air-borne fluoride was the major factor for higher prevalence of fluorosis in these rural areas.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Sampling, characterization, and remote sensing of aerosols formed in the atmospheric hydrolysis of uranium hexafluoride

    SciTech Connect

    Bostick, W.D.; McCulla, W.H.; Pickrell, P.W.

    1984-05-01

    When gaseous uranium hexafluoride (UF/sub 6/) is released into the atmosphere, it rapidly reacts with ambient moisture to form an aerosol of uranyl fluoride (UO/sub 2/F/sub 2/) and hydrogen fluoride (HF). As part of our Safety Analysis program, we have performed several experimental releases of HF/sub 6/ in contained volumes in order to investigate techniques for sampling and characterizing the aerosol materials. The aggregate particle morphology and size distribution have been found to be dependent upon several conditions, including the temperature of the UF/sub 6/ at the time of its release, the relative humidity of the air into which it is released, and the elapsed time after the release. Aerosol composition and settling rate have been investigated using stationary samplers for the separate collection of UO/sub 2/F/sub 2/ and HF and via laser spectroscopic remote sensing (Mie scatter and infrared spectroscopy). 25 refs., 16 figs., 5 tabs.

  9. 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
    % ...

  10. Compressive strength, fluoride release and recharge of fluoride-releasing materials.

    PubMed

    Xu, Xiaoming; Burgess, John O

    2003-06-01

    The compressive strength, fluoride releases and recharge profiles of 15 commercial fluoride-releasing restorative materials have been studied. The materials include glass ionomers (Fuji IX, Ketac Molar, Ketac Silver, and Miracle Mix), resin-modified glass ionomers (Fuji II LC Improved, Photac-Fil, and Vitremer), compomers (Compoglass, Dyract AP, F2000, and Hytac) and composite resins (Ariston pHc, Solitaire, Surefil and Tetric Ceram). A negative linear correlation was found between the compressive strength and fluoride release (r(2)=0.7741), i.e., restorative materials with high fluoride release have lower mechanical properties. The fluoride-releasing ability can be partially regenerated or recharged by using a topical fluoride agent. In general, materials with higher initial fluoride release have higher recharge capability (r(2)=0.7088). Five equations have been used in curve fitting to describe the cumulative fluoride release from different materials. The equation [F](c)=[F](I)(1-e(-bt))+betat best describes the cumulative fluoride release for most glass ionomers, resin-modified glass ionomers, and some high fluoride-releasing compomers and composites, whereas [F](c)=[F](I)/(t(1/2)+t)+alphat best describes the cumulative fluoride release for most compomers and composite resins. The clinic applications of different fluoride-releasing materials have also been discussed.

  11. 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.

  12. Topical use of fluorides for caries control.

    PubMed

    Pessan, Juliano Pelim; Toumba, Kyriacos Jack; Buzalaf, Marília Afonso Rabelo

    2011-01-01

    Since the early findings on the protective effects of fluoride present in drinking water upon caries incidence and prevalence, intensive research has been conducted in order to determine the benefits, safety, as well as the cost-effectiveness of other modalities of fluoride delivery. The present chapter reviews the various forms of topical fluoride use - professionally and self-applied - with special emphasis on clinical efficacy and possible side effects. The most widely used forms of fluoride delivery have been subject of several systematic reviews, providing strong evidence supporting the use of dentifrices, gels, varnishes and mouth rinses for the control of caries progression. Dentifrices with fluoride concentrations of 1,000 ppm and above have been shown to be clinically effective in caries prevention when compared to a placebo treatment, but the evidence regarding formulations with 450-550 ppm is still subject of debate. Therefore, the recommendation for low-fluoride dentifrice use must take into account both risks and benefits. The evidence for the combined use of two modalities of fluoride application in comparison to a single modality is still inconsistent, implying that more studies with adequate methodology are needed to determine the real benefits of each method. Considering the currently available evidence and risk-benefit aspects, it seems justifiable to recommend the use of fluoridated dentifrices to individuals of all ages, and additional fluoride therapy should also be targeted towards individuals at high caries risk.

  13. 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).

  14. Determination of Ammonium in Aqueous Samples by Gas Phase Light Scattering Using Hydrogen Chloride Gas as a Derivatizing Reagent Followed by Nondispersive Atomic Fluorescence Spectrometry.

    PubMed

    Duan, Xuchuan; Fang, Jinliang; Sun, Rui

    2017-01-01

    A sensitive method was developed for the determination of ammonium in an aqueous solution based on gas phase light scattering. In a stream of carrier gas, the gaseous ammonia from the alkalized solution formed a volatile ammonium chloride derivative by reacting with gaseous hydrogen chloride; the gaseous ammonium chloride was analyzed by nondispersive atomic fluorescence spectrometry. The mechanisms of the method are elucidated based on evaporative light scattering detection. Parameters such as temperature, amount of sodium hydroxide, and carrier gas flow rate were studied. Under optimal conditions, the detection limit of ammonium-nitrogen was 0.045 μg. The method was successfully applied to the determination of ammonium in certified reference materials, and tap and seawater samples.

  15. Cellulose supported layered double hydroxides for the adsorption of fluoride from aqueous solution.

    PubMed

    Mandal, S; Mayadevi, S

    2008-06-01

    Cellulose supported layered double hydroxides (CSLDHs) were synthesized and tested for adsorption of fluoride in aqueous medium. Three samples of cellulose supported LDHs were synthesized by varying the LDH loading on cellulose. The raw cellulose, unsupported LDH and cellulose supported LDHs were characterized by XRD, SEM and BET surface area. Batch adsorption as well as fixed-bed column experiments were performed for determining the fluoride adsorption characteristics of CSLDHs. The fluoride adsorption properties of CSLDHs were found to be superior to that of reported adsorbents, including activated alumina and carbon nanotubes. Defluoridation capacity of the CSLDHs was 2-4 times higher than that of unsupported LDH. The cellulose supported LDH, CSLDH-50, having an LDH loading of 27% showed maximum fluoride uptake capacity (5.29 mg g(-1) of CSLDH, 25.18 mg g(-1) of LDH) in fixed-bed column study.

  16. 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

  17. Long-term exposure to fluoride in drinking water and sister chromatid exchange frequency in human blood lymphocytes.

    PubMed

    Li, Y; Liang, C K; Katz, B P; Brizendine, E J; Stookey, G K

    1995-08-01

    The genetic toxicity of fluoride has been investigated extensively by various test systems. However, results obtained have been inconsistent. Fluoride has been reported to be non-genotoxic, genotoxic, and synergistic or antagonistic with certain mutagens. To date, there are no published human studies on the genotoxicity of fluoride. The purpose of this investigation was to determine genotoxic risks of long-term exposure to various concentrations of fluoride in drinking water in humans with normal or inadequate nutrition. Six groups of subjects with either normal or inadequate nutritional intakes were selected from areas of approximately 0.2, 1.0, or 4.8 ppm (10.5, 52.6, or 252.6 mumol/L) fluoride in water. The subjects had been continuous residents in the area for at least 35 years. Samples of drinking water, plasma, and urine were analyzed for fluoride content. Blood lymphocytes were examined to determine the frequency of sister chromatid exchange (SCE). Blood chemistry and electrolytes were also analyzed. The results showed that average daily fluoride intake as well as urine and plasma fluoride levels increased with increase in the fluoride content of the drinking water. The blood chemistry and electrolyte values were within the normal range for all populations, but several parameters were significantly different. While the numerical differences were small, the subjects with low fluoride in the water (0.11 and 0.23 ppm or 5.8 and 12.1 mumol/L) had significantly higher SCE frequencies than those with higher fluoride exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. 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.

  19. 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.

  20. 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.

  1. 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

    2013-11-04

    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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Fluoride intake and its safety among heavy tea drinkers in a British fluoridated city.

    PubMed

    Jenkins, G N

    1991-01-01

    Tea-drinking in very young children has been studied in a British city. The results suggested that the fluoride in tea would, in some cases, be sufficient to influence caries. Clinical findings to some extent supported this. The main purpose of the investigation reported here was to determine maximum possible fluoride intake in adults who were heavy tea drinkers in a fluoridated city and relate it to toxic thresholds. Heavy tea drinkers were traced through Health Visitors and voluntary organizations and the volumes and fluoride concentrations of their drinks were measured. Even the highest intake found (9 mg) is below the probable intake in Bartlett, Texas (8 ppm of fluoride), in relation to which no undesirable symptoms have been reported (Leone et al. 1954). This confirms the safety of fluoridation. The effects on fluoride concentration of evaporating soft and hard fluoride-containing waters to small bulk were compared. The results showed ceilings of 3 ppm of fluoride in hard water and about 14 ppm in soft water, much higher than the levels expected on the basis of the usually stated solubility of CaF2 (16 or 8 ppm of fluoride). However, under normal household conditions, it is most unlikely that dangerous levels of fluoride would be ingested from boiled water.

  7. 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.

  8. Review on fluoride, with special emphasis on calcium fluoride mechanisms in caries prevention.

    PubMed

    ten Cate, J M

    1997-10-01

    Low concentrations of fluoride have a beneficial effect on enamel and dentin de- and remineralization. After fluoride treatments, such as topical applications, rinses or dentifrices, salivary fluoride concentrations decrease exponentially in a biphasic manner to very low concentrations within a few hours. For treatments to be effective over periods longer than the brushing and the following salivary clearance, fluoride needs to be deposited and slowly released. Calcium fluoride (or like) deposits act in such a way, owing to a surface covering of phosphate and/or proteins, which makes the CaF2 less soluble under in vivo conditions than in a pure form in inorganic solutions. Moreover, due to the phosphate groups on the surface of the calcium fluoride globules, fluoride is assumed to be released with decreasing pH when the phosphate groups are protonated in the dental plaque.

  9. 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

  10. Does Fluoride Affect Serum Testosterone and Androgen Binding Protein with Age-Specificity? A Population-Based Cross-Sectional Study in Chinese Male Farmers.

    PubMed

    Duan, Leizhen; Zhu, Jingyuan; Wang, Keyan; Zhou, Guoyu; Yang, Yuejin; Cui, Liuxin; Huang, Hui; Cheng, Xuemin; Ba, Yue

    2016-12-01

    Many studies have demonstrated that exposure to excess fluoride was associated with a variety of diseases. Little is known about the variation of testosterone (T) levels caused by fluoride exposure. The aim of this study is to explore the association of fluoride exposure and age with serum T and androgen-binding protein (ABP) levels in male farmers. A cross-sectional study was conducted in a county of Henan Province, China, including high fluoride exposure from drinking water villages and control villages. Male farmers aged 18-55 years old who lived in these villages were recruited by cluster sampling and divided into a higher fluoride exposure group (HFG) and a lower fluoride exposure group (LFG) according to the level of urinary fluoride. Levels of T and ABP in serum were measured using chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) respectively. Markedly lower T levels were observed in male farmers from the HFG than in those from the LFG (t = 2.496, P < 0.05). Furthermore, younger farmers, 18-29 and 30-39 years old, may be the most likely to have lower T levels when exposed to fluoride (P < 0.05). No significant differences were observed in serum ABP levels in all male farmers between the two groups with different fluoride exposure. These results supported that excess fluoride exposure decreased serum T levels of male farmers with age-specificity.

  11. Fluoride effects: the two faces of janus.

    PubMed

    Gazzano, E; Bergandi, L; Riganti, C; Aldieri, E; Doublier, S; Costamagna, C; Bosia, A; Ghigo, D

    2010-01-01

    The behavior of fluoride ions in the human organism is a classic example of double-edged sword. On the one hand the daily supplementation with fluoride is undoubtedly an important preventing factor in protecting teeth from caries, and, as an important mitogenic stimulus for osteoblasts, it may enhance mineral deposition in bone, but on the other hand fluoride, above a threshold concentration, has been demonstrated to be toxic. We present here a brief review of fluoride metabolism and exposure, its use in caries prevention and its effects on bone, followed by an updating about the main hypotheses concerning its mechanism of action and toxicity. The effects of fluoride have been related mainly to its ability to evoke the activation of G proteins and the inhibition of phosphotyrosine phosphatases, leading to an intracellular increase of tyrosine phosphorylation and activation of the mitogen-activated protein kinase pathway, and its capacity to cause generation of reactive oxygen species. We present also a unifying hypothesis accounting for these apparently different effects, although the available experimental models and conditions are highly variable in the literature. A lot of experiments still need to be performed to clarify the positive and negative effects of fluoride. Finding the mechanisms accounting for fluoride toxicity is an important point: indeed, the use of fluoride has been proposed in the preparation of new biomaterials to be inserted in the bone, in order to improve their stable and safe integration.

  12. 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.

  13. Calcium fluoride formation on sound enamel using fluoride solutions with and without lactate.

    PubMed

    Harding, A M; Zero, D T; Featherstone, J D; McCormack, S M; Shields, C P; Proskin, H M

    1994-01-01

    The formation of calcium (Ca) fluoride (CaF2) on bovine enamel blocks during clinically relevant treatment times using neutral fluoride (F) solutions (0.26 mol/l F) with and without 0.1 mol/l lactate was investigated. Uncoated and pellicle-coated blocks were evaluated for alkali-soluble (1 mol/l KOH, three consecutive 24-hour treatments) Ca, PO4, and F after treatment by the F solutions for 0, 5, 15, 30, and 60 min. There was an overall time-related increase in F recovery, while Ca tended to remain at baseline levels. Less F was recovered from the pellicle-coated blocks. The addition of lactate to the F treatment solution did not result in an overall increase in alkali-soluble F recovery, but did result in the formation of cuboidal shaped crystals which closely approached the morphology of pure CaF2. A 1:2 stoichiometric ratio Ca:2F (mol:mol) was not established based on chemical analyses. The ultrastructural and elemental composition of surface deposits on the samples, as determined using scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy, established the presence of CaF2 after 24-hour F treatments; however, it was not possible to directly demonstrate the formation of CaF2 after clinically relevant treatment times.

  14. 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.

  15. Effects of daily fluoride exposures on fluoride release by glass ionomer-based restoratives.

    PubMed

    Freedman, Rick; Diefenderfer, Kim E

    2003-01-01

    It is well documented that glass ionomer cements absorb and release fluoride following single fluoride exposures. This study examined fluoride release among three glass ionomer-based restorative materials following multiple daily exposures to three topical fluoride regimens. Using a Delrin mold, 32 cylindrical specimens, each of a glass ionomer (Ketac-Fil), resin-modified glass ionomer (Photac-Fil) and polyacid-modified resin (Dyract AP) were created. Each specimen was subjected to one of four daily treatments (n = 8): (1) no fluoride treatment (control); (2) application of a fluoride dentifrice (1000 ppm) for one minute once daily; (3) application of the same dentifrice for one minute twice daily; (4) the same regimen as (3), plus immersion in a 0.05% sodium fluoride (NaF) mouth rinse (225 ppm) for one minute immediately following the second dentifrice application. Each specimen was suspended in a polyethylene test tube containing 1.0 ml demineralizing solution (pH 4.3) at 37 degrees C for six hours, then transferred to a new test tube containing 1.0 ml remineralizing solution (pH 7.0) at 37 degrees C for 18 hours. Fluoride treatments were completed at the time of transfer daily for seven days. Media solutions were buffered with equal volumes of TISAB II; fluoride levels were measured using a digital ion analyzer and fluoride electrode. Fluoride release decreased significantly from Day 1 to Day 3 for all materials regardless of fluoride treatment (Repeated Measures ANOVA, Tukey HSD, p < 0.05). All specimens released significantly more fluoride in demineralizing solution than in remineralizing solution. For Days 2-7, Treatment 4 produced greater fluoride release than both the control and Treatment 2 for all three materials (p < 0.05); For each material, the fluoride release produced by Treatments 3 and 4 was statistically similar on most days throughout the study. By Day 7, Photac-Fil demonstrated both the greatest total fluoride release and the greatest

  16. 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

  17. 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.

  18. Hydrogen mitigation in submerged arc welding

    NASA Astrophysics Data System (ADS)

    Klimowicz, Steven

    removes the moisture that is added by the water based binder. The second phase of the project was to modify the flux with fluoride additions to remove hydrogen from the arc while welding. The introduction of fluorine into the arc would lower the amount of hydrogen that may be absorbed as diffusible hydrogen by the weld metal. To select the fluorides a series of thermodynamic calculations were performed as well as simple tests to determine the fluorides behavior in a welding arc and flux. From these tests the following fluorides were selected to be used to be added to EM12K flux as oneweight percent additions: SrF 2, K2TiF6, K2SiF6, and LiF. Welds were then run with the experimental fluxes according to AWS A4.3 standard for diffusible hydrogen testing. From these tests it was found that none experimental fluxes were able to achieve a diffusible hydrogen content lower than the original EM12K flux. It was also found that fluoride reduction in a simple flux is a better predictor of fluoride effectiveness than decomposition temperature.

  19. 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

  20. 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.

  1. 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.

  2. Rotational Energy Transfer in Highly Vibrationally Excited Hydrogen Fluoride and Deuterium Fluoride.

    DTIC Science & Technology

    1983-03-16

    vibrational and rotational relaxation in HF(v - 2). These experiment ~ determine the magnitudes of the total vibrational relaxation rate constants for HF( ve 1...iterative fitting scheme which incorporates scaling relations among the rate constants. t.; Accession For NTIS GRA&I DTIC TAB Uiiannouic ed -. Just if...agrees fairly well with two others and a scaling law analysis. (R. A. Copeland, D. J. Pearson, J. Mt. Robinson, and F. F. Crim, J. Chem. Phys. 77, 3974

  3. 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.

  4. 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.

  5. 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

    2014-01-03

    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.

  6. 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.

  7. 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...

  8. 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...

  9. 21 CFR 872.6870 - Disposable fluoride tray.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  10. 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,…

  11. 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)

  12. Brushing abrasion of eroded dentin after application of sodium fluoride solutions.

    PubMed

    Attin, T; Zirkel, C; Hellwig, E

    1998-01-01

    The aim of the present in vitro study was to evaluate the influence of sodium fluoride solutions on brushing abrasion of eroded dentin. Dentin specimens were prepared from 60 bovine incisors. The specimens were embedded in acrylic resin, ground flat, polished and subsequently covered with tape exposing an area of 1.8 mm x 10.0 mm in the center of the exposed dentin. The samples were alternatingly stored in a demineralizing solution (5 min) and a remineralizing solution (1 min) for 5 times. The erosive soft drink Sprite light(R) served as a demineralizing solution and artificial saliva was used as a remineralizing solution. Prior to storage in artificial saliva 15 specimens were each treated for 1 min with 250 and 2,000 ppm fluoride solution, respectively. Fifteen specimens were treated with distilled water instead of the fluoride solution (= eroded controls). The remaining samples were neither eroded with the soft drink nor fluoridated (= uneroded controls). After each immersion in artificial saliva the specimens were submitted to abrasion in a toothbrushing machine. After 5 demineralization-remineralization brushing cycles the total amount of tooth wear due to erosion and subsequent abrasion was profilometrically evaluated. Statistical analysis revealed the significantly lowest wear in the uneroded controls and the highest amount of abrasion in the eroded controls. Application of the fluoride solutions increased the wear resistance of the eroded dentin specimens, showing significantly better protection by the high-concentration compared to the low-concentration solution. The susceptibility to abrasion of the eroded dentin specimens treated with the high-concentration fluoride solution did not differ significantly from the uneroded dentin samples. It is concluded that application of 2,000 ppm sodium fluoride solutions immediately before toothbrushing significantly reduces abrasion of eroded dentin in vitro.

  13. 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.

  14. 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.

  15. Relationship between water, urine and serum fluoride and fluorosis in school children of Jhajjar District, Haryana, India

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Lata, Suman; Yadav, Jyoti; Yadav, J. P.

    2016-10-01

    The present study was undertaken to determine the relationship between fluoride in water, urine and serum and dental fluorosis. The fluoride level in water and urine were measured spectrophotometrically by using acid zirconyl and SPADNS reagents, while the fluoride level in serum was determined by ion selective electrode meter. Dental fluorosis survey was conducted with the help of Performa prescribed by Rajiv Gandhi Drinking Water Mission and the use of Tooth Surface Index for Fluorosis. Mean fluoride values in water samples of Jhajjar City and Dadanpur and Dariyapur villages of Jhajjar District were measured to be 2.17 (range from 1.92 to 2.60 mg/L), 2.81 (range from 2.53 to 3.14 mg/L) and 2.22 mg/L (range from 1.63 to 3.33 mg/L), respectively. The mean fluoride values in the urine samples of children were found to be 1.51 (range from 0.05 to 2.64 mg/L), 1.71 (range from 0.69 to 2.80 mg/L) and 1.45 mg/L (range from 0.31 to 2.50 mg/L) at Jhajjar City and Dadanpur and Dariyapur sites, respectively. Serum fluoride was detected in the blood samples of children, who have high urinary fluoride at these three sites. The mean serum fluoride level was reported to be 0.15, 0.34 and 0.17 mg/L, respectively. A total of 842 children were also analyzed for dental fluorosis. The mean values of fluorosis-affected children in Jhajjar, Dadanpur and Dariyapur were 51.90, 94.63 and 36.84 %, respectively. A significantly positive correlation between water, urine, serum fluoride concentration and fluorosis was seen.

  16. Physiologic conditions affect toxicity of ingested industrial fluoride.

    PubMed

    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.

  17. 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

  18. 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

  19. 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.

  20. A comparative study of removal of fluoride from contaminated water using shale collected from different coal mines in India.

    PubMed

    Biswas, Gargi; Dutta, Manjari; Dutta, Susmita; Adhikari, Kalyan

    2016-05-01

    Low-cost water defluoridation technique is one of the most important issues throughout the world. In the present study, shale, a coal mine waste, is employed as novel and low-cost adsorbent to abate fluoride from simulated solution. Shale samples were collected from Mahabir colliery (MBS) and Sonepur Bazari colliery (SBS) of Raniganj coalfield in West Bengal, India, and used to remove fluoride. To increase the adsorption efficiency, shale samples were heat activated at a higher temperature and samples obtained at 550 °C are denoted as heat-activated Mahabir colliery shale (HAMBS550) and heat-activated Sonepur Bazari colliery shale (HASBS550), respectively. To prove the fluoride adsorption onto different shale samples and ascertain its mechanism, natural shale samples, heat-activated shale samples, and their fluoride-loaded forms were characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction study, and Fourier transform infrared spectroscopy. The effect of different parameters such as pH, adsorbent dose, size of particles, and initial concentration of fluoride was investigated during fluoride removal in a batch contactor. Lower pH shows better adsorption in batch study, but it is acidic in nature and not suitable for direct consumption. However, increase of pH of the solution from 3.2 to 6.8 and 7.2 during fluoride removal process with HAMBS550 and HASBS550, respectively, confirms the applicability of the treated water for domestic purposes. HAMBS550 and HASBS550 show maximum removal of 88.3 and 88.5 %, respectively, at initial fluoride concentration of 10 mg/L, pH 3, and adsorbent dose of 70 g/L.

  1. Palladium-citric acid-ammonium fluoride as a matrix modifier for overcoming of interferences occurring during the direct determination of Sn in aqua regia extracts from environmental samples by D2-ETAAS.

    PubMed

    Husáková, Lenka; Srámková, Jitka; Cernohorský, Tomás; Urbanová-Dolezalová, Iva

    2009-02-15

    When tin is to be determined in such a complex matrix like aqua regia extracts of environmental samples by electrothermal atomic absorption spectrometry (ETAAS), spectral interferences occur when deuterium-lamp (D(2)) background correction is used, even using high pyrolysis temperature of 1400 degrees C achieved with palladium with citric acid chemical modifier. We have found that the further addition of NH(4)F to palladium with citric acid chemical modifier is essential for overcoming the above-mentioned problems for which aluminium oxide is most probably responsible. It is supposed, that NH(4)F enables volatilization of the alumina matrix formed by hydrolysis from the chloride salt and interfering in a gas phase via the formation of AlF(3) which could be, in contrast to aluminium oxide, removed from the graphite furnace during the pyrolysis stage. Using the proposed chemical modifier, the direct and accurate determination of Sn in aqua regia extracts from rocks, soils and sediments is possible even when using matrix free standard solutions. This presumption was confirmed by the analysis of certified reference samples and by the comparison with inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS) method. Characteristic mass and LOD value for the original sample (10-microL aliquots of sample) was 17 pg and 0.055 microg g(-1), respectively.

  2. 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.

  3. 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

  4. 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.

  5. 76 FR 37129 - Determination That SODIUM FLUORIDE F 18 (Sodium Fluoride F-18) Injection, 10 to 200 Millicuries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-24

    ... HUMAN SERVICES Food and Drug Administration Determination That SODIUM FLUORIDE F 18 (Sodium Fluoride F... Drug Administration (FDA) has determined that SODIUM FLUORIDE F 18 (sodium fluoride F-18) injection, 10... effectiveness. This determination will allow FDA to approve abbreviated new drug applications (ANDAs) for...

  6. Influence of microwave heating on fluoride, chloride, nitrate and sulfate concentrations in water.

    PubMed

    Figueiredo, Eduardo Costa; Dias, Jailson Cardoso; Kubota, Lauro Tatsuo; Korn, Mauro; Oliveira, Pedro Vitoriano; Arruda, Marco Aurélio Zezzi

    2011-10-15

    This paper describes a study about the influence of microwave radiation using closed vessels on fluoride, chloride, nitrate and sulfate concentrations in aqueous media. The experiments were processed by heating water using PFA vessels and a microwave cavity oven, determining the anions by ion chromatography. The influence of the exposure time, the atmospheric composition, the kind of heating (water bath or microwave radiation) and the possible formation of hydrogen peroxide were investigated. The limits of quantification for fluoride, chloride, nitrate and sulfate were respectively of 0.17, 0.15, 0.55 and 0.57 μg L(-1), and precision, expressed as RSD, was <4% for all considered anions. The hydrogen peroxide was quantified by spectrophotometry, and the limit of quantification and precision were 24 μg L(-1) and <5% (n=10), respectively. The results demonstrate a significant increase in the anion concentration levels (between 63 and 89%) when microwave heating was used in comparison with heating by water bath. In addition, these changes observed can be mainly attributed to the species transfers, either between gaseous (atmospheric gases) and liquid (water) phases for nitrate, or between vessels walls and water for fluoride, chloride and sulfate. Additionally, hydrogen peroxide concentration higher than 45 μg L(-1) was determined when water was exposed to microwave radiation.

  7. Theoretical proton affinity and fluoride affinity of nerve agent VX.

    PubMed

    Bera, Narayan C; Maeda, Satoshi; Morokuma, Keiji; Viggiano, Al A

    2010-12-23

    Proton affinity and fluoride affinity of nerve agent VX at all of its possible sites were calculated at the RI-MP2/cc-pVTZ//B3LYP/6-31G* and RI-MP2/aug-cc-pVTZ//B3LYP/6-31+G* levels, respectively. The protonation leads to various unique structures, with H(+) attached to oxygen, nitrogen, and sulfur atoms; among which the nitrogen site possesses the highest proton affinity of -ΔE ∼ 251 kcal/mol, suggesting that this is likely to be the major product. In addition some H(2), CH(4) dissociation as well as destruction channels have been found, among which the CH(4) + [Et-O-P(═O)(Me)-S-(CH(2))(2)-N(+)(iPr)═CHMe] product and the destruction product forming Et-O-P(═O)(Me)-SMe + CH(2)═N(+)(iPr)(2) are only 9 kcal/mol less stable than the most stable N-protonated product. For fluoridization, the S-P destruction channel to give Et-O-P(═O)(Me)(F) + [S-(CH(2))(2)-N-(iPr)(2)](-) is energetically the most favorable, with a fluoride affinity of -ΔE ∼ 44 kcal. Various F(-) ion-molecule complexes are also found, with the one having F(-) interacting with two hydrogen atoms in different alkyl groups to be only 9 kcal/mol higher than the above destruction product. These results suggest VX behaves quite differently from surrogate systems.

  8. Hydrogen production

    NASA Technical Reports Server (NTRS)

    England, C.; Chirivella, J. E.; Fujita, T.; Jeffe, R. E.; Lawson, D.; Manvi, R.

    1975-01-01

    The state of hydrogen production technology is evaluated. Specific areas discussed include: hydrogen production fossil fuels; coal gasification processes; electrolysis of water; thermochemical production of hydrogen; production of hydrogen by solar energy; and biological production of hydrogen. Supply options are considered along with costs of hydrogen production.

  9. Fluoride

    MedlinePlus

    ... straight from the bottle or mixed with cereal, fruit juice, or other foods. Use a dropper or an ... mouth, chewed, or added to drinking water or fruit juice. Tablets also may be added to water for ...

  10. Fluoride Retention following the Professional Topical Application of 2% Neutral Sodium Fluoride Foam

    PubMed Central

    Song, Wenqun; Toda, Shinji; Komiyama, Eri; Komiyama, Karin; Arakawa, Yuki; He, Dawei; Arakawa, Hirohisa

    2011-01-01

    The objective of the present research was to determine the appropriate amount of fluoride to use professional topical application and the residual amounts of fluoride in the oral cavity using a 2% neutral sodium fluoride (NaF) foam with a dedicated tray. Using dentition study models, a method for determining the appropriate amount of NaF foam was investigated. In eight adult subjects, the appropriate amount of NaF foam, the concentration of fluoride in the saliva following professional topical application, and the amount of residual fluoride in the oral cavity following professional topical application was examined. The results indicated that the appropriate amount of NaF foam was approximately 0.8 g, the amount of residual fluoride in the oral cavity was approximately 25% of the amount of foam used. PMID:21754931

  11. Design Manual: Removal of Fluoride from Drinking Water ...

    EPA Pesticide Factsheets

    This document is an updated version of the Design Manual: Removal of Fluoride from Drinking Water Supplies by Activated Alumina (Rubel, 1984). The manual is an in-depth presentation of the steps required to design and operate a fluoride removal plant using activated alumina (AA), which is a reliable and cost-effective process for treating excess fluoride from drinking water supplies. Design Manual on removing fluoride from drinking water to support the fluoride MCL - manual

  12. 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.

  13. Enriched fluoride sorption using alumina/chitosan composite.

    PubMed

    Viswanathan, Natrayasamy; Meenakshi, S

    2010-06-15

    Alumina possesses an appreciable defluoridation capacity (DC) of 1566 mg F(-)/kg. In order to improve its DC, it is aimed to prepare alumina polymeric composites using the chitosan. Alumina/chitosan (AlCs) composite was prepared by incorporating alumina particles in the chitosan polymeric matrix, which can be made into any desired form viz., beads, candles and membranes. AlCs composite displayed a maximum DC of 3809 mg F(-)/kg than the alumina and chitosan (52 mg F(-)/kg). The fluoride removal studies were carried out in batch mode to optimize the equilibrium parameters viz., contact time, pH, co-anions and temperature. The equilibrium data was fitted with Freundlich and Langmuir isotherms to find the best fit for the sorption process. The calculated values of thermodynamic parameters indicate the nature of sorption. The surface characterisation of the sorbent was performed by FTIR, AFM and SEM with EDAX analysis. A possible mechanism of fluoride sorption by AlCs composite has been proposed. Suitability of AlCs composite at field conditions was tested with a field sample taken from a nearby fluoride-endemic village. This work provides a potential platform for the development of defluoridation technology.

  14. Mechanical Properties of Calcium Fluoride-Based Composite Materials

    PubMed Central

    Kleczewska, Joanna; Pryliński, Mariusz; Podlewska, Magdalena; Sokołowski, Jerzy; Łapińska, Barbara

    2016-01-01

    Aim of the study was to evaluate mechanical properties of light-curing composite materials modified with the addition of calcium fluoride. The study used one experimental light-curing composite material (ECM) and one commercially available flowable light-curing composite material (FA) that were modified with 0.5–5.0 wt% anhydrous calcium fluoride. Morphology of the samples and uniformity of CaF2 distribution were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Mechanical properties were tested after 24-hour storage of specimens in dry or wet conditions. Stored dry ECM enriched with 0.5–1.0 wt% CaF2 showed higher tensile strength values, while water storage of all modified ECM specimens decreased their tensile strength. The highest Vickers hardness tested after dry storage was observed for 2.5 wt% CaF2 content in ECM. The addition of 2.0–5.0 wt% CaF2 to FA caused significant decrease in tensile strength after dry storage and overall tensile strength decrease of modified FA specimens after water storage. The content of 2.0 wt% CaF2 in FA resulted in the highest Vickers hardness tested after wet storage. Commercially available composite material (FA), unmodified with fluoride addition, demonstrated overall significantly higher mechanical properties. PMID:28004001

  15. 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.

  16. Nuclear quantum effects and hydrogen bonding in liquids.

    PubMed

    Raugei, Simone; Klein, Michael L

    2003-07-30

    We have employed ab initio path integral molecular dynamics simulations to investigate the role of nuclear quantum effects on the strength of hydrogen bonds in liquid hydrogen fluoride. Nuclear quantum effects are shown to be responsible for a stronger hydrogen bond and an enhanced dipole-dipole interaction, which lead, in turn, to a shortening of the H...F intrachain distance. The simulation results are analyzed in terms of the electronic density shifts with respect to a purely classical treatment of the nuclei. The observed enhanced hydrogen-bond interaction, which arises from a coupling of intra- and intermolecular effects, should be a general phenomenon occurring in all hydrogen-bonded systems.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Hydrogen systems

    SciTech Connect

    Veziroglu, T.N.; Zhu, Y.; Bao, D.

    1985-01-01

    This book presents the papers given at a symposium on hydrogen fuels. Topics considered at the symposium included hydrogen from fossil fuels, electrolysis, photolytic hydrogen generation, thermochemical and photochemical methods of hydrogen production, catalysts, hydrogen biosynthesis, novel and hybrid methods of hydrogen production, storage and handling, metal hydrides and their characteristics, utilization, hydrogen fueled internal combustion engines, hydrogen gas turbines, hydrogen flow and heat transfer, fuel cells, synthetic hydrocarbon fuels, thermal energy transfer, hydrogen purification, research programs, economics, primary energy sources, environmental impacts, and safety.

  2. 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.

  3. Manufacture of high purity metal fluorides

    SciTech Connect

    Vance, J.M.

    1984-01-01

    The Oak Ridge Gaseous Diffusion Plant has been developing technologies of many kinds since the early forties. The primary purpose of this R and D was to reduce the amount of electrical power and capital expense associated with the enrichment of uranium in the 235 isotope. One area that has received a lot of attention is the chemistry of fluorine and metal fluorides. The producing facility at ORGDP is a chemical pilot plant which has been used through the years to demonstrate new processes. Presently existing in this facility are: absorption columns which have been used to remove trace quantities of krypton and oxides of nitrogen and sulfur from gas streams; a flame reactor that is being used to reduce isotopically altered sulfur hexafluoride for conversion to SO/sub 2/ which will be used in acid rain studies; an environmental hold system in which methods were developed to remove or neutralize environmental insulting compounds; a fluid bed reactor, and of course the tungsten hexafluoride process. A rhenium hexafluoride facility is also located in the pilot plant. It is basically the same as the tungsten line with three small muffles being used in place of the large WF6 reactor. The product from each process is heated and transferred to approved 5-inch shipping cylinders and transported to the analytical chemistry laboratory for sampling and analysis. These cylinders must be used for shipment and may require modification of the customer facility to accommodate them. Liquid samples are obtained from the product cylinders and a visual examination of the samples for color and melting temperature provides a good indication of the conversion. X-ray fluorescence is utilized to determine the amount of tungsten and the percent conversion to the hexafluoride is calculated from the weighed sample. Infrared in addition to mass spectrometer analyses are performed to verify the findings. The material is then analyzed by spectrographic methods for contaminants.

  4. The effect of fluoride surface modification of ceramic TiO2 on the surface properties and biological response of osteoblastic cells in vitro.

    PubMed

    Tiainen, H; Monjo, M; Knychala, J; Nilsen, O; Lyngstadaas, S P; Ellingsen, J E; Haugen, H J

    2011-08-01

    This study investigates the effect of fluoride surface modification on the surface properties of polycrystalline ceramic TiO(2) and the biological response of murine osteoblast cells to fluoride-modified TiO(2) in vitro. Fluoride concentrations up to 9 at.% were detected and the fluoride was found to bind to the surface in a ligand exchange reaction between surface hydroxyl groups and the fluoride anions from the HF. No significant changes in the surface topography were detected. In vitro experiments were performed in order to evaluate the biological response of the MC3T3-E1 cells to the fluoride-modified ceramic TiO(2) surfaces. No difference in the lactate dehydrogenase (LDH) activity was seen in comparison to unmodified samples, apart from the highest fluoride concentration (∼9 at.%) which was found to be more toxic to the cells. Real-time PCR analysis showed no conclusive evidence for the fluoride-induced promotion of osteoblast differentiation as no significant increase in the collagen-1, osteocalcin, or BMP-2 mRNA levels was detected on the fluoride-modified ceramic TiO(2) surfaces apart from one group, which showed an elevated osteocalcin level and higher number of cells. Since the observed grain boundary corrosion is also anticipated to reduce the mechanical properties of ceramic TiO(2), this surface modification method may not be an ideal method for improving the osteogenic response of ceramic TiO(2) scaffolds.

  5. Materials corrosion in molten lithium fluoride-sodium fluoride-potassium fluoride eutectic salt

    NASA Astrophysics Data System (ADS)

    Olson, Luke Christopher

    Static corrosion studies were undertaken to determine the compatibility of several candidate high temperature materials for a heat transfer loop in a molten alkali fluoride eutectic salt, LiF-NaF-KF: 46.5-11.5-42 mol % (commonly referred to as FLiNaK), as well as a molten chloride near eutectic salt, KCl-MgCl2: 68-32 mol %. Several high temperature alloys: Hastelloy-N, Hastelloy-X, Haynes-230, Inconel-617, and Incoloy-800H, Nb-1Zr, a nearly pure Ni alloy Ni-201, and a C/SiSiC ceramic were exposed to molten FLiNaK at 850°C for 500 h in sealed graphite crucibles under an argon cover gas. Corrosion occurred predominantly from dealloying of Cr from the Cr bearing alloys, an effect that was particularly pronounced at the grain boundaries. Corrosion was noted to occur from selective attack of the Si phase in the C/SiSiC ceramic. Alloy weight-loss/area due to molten fluoride salt exposure correlated with the initial Cr-content of the alloys, and was consistent with the Cr-content measured in the salts after corrosion tests. The alloys' weight-loss/area was also found to correlate to the concentration of carbon present in the nominally 20% Cr containing alloys, due to the formation of chromium carbide phases at the grain boundaries. The corrosion mechanisms for the chloride based salt were found to be similar to those observed in FLiNaK, but the chemical attack was found to be less aggressive. Sulfamate Ni electroplating and Mo plasma spraying of Fe-Ni-Cr alloy coupons was investigated to mitigate Cr dissolution. A chemical vapor deposited pyrolytic carbon and SiC coating was also investigated to protect the C/SiSiC composites. Results indicate that Ni-plating has the potential to provide protection against alloy corrosion in molten fluoride salts. Furthermore, the presence of a chromium-oxide interlayer at the interface of the Ni-plating and alloy substrate can further improve the efficacy of the Ni-plating. The pyrolytic carbon and SiC coating on the C/SiSiC composites

  6. 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.

  7. Effect of fluoride intoxication on the levels of intestinal antioxidants studied in rats.

    PubMed

    Shanthakumari, D; Srinivasalu, S; Subramanian, S

    2007-03-01

    High concentration of fluorine is noxious to the health of humans and animals. Analysis of fluoride in water samples meant for human consumption in the Vellore District of Tamil Nadu, India, revealed its presence above the permissible limit (4.56 ppm). The present study was aimed to investigate the toxic effects of oral administration of the water sample that contains the highest fluoride content on the status of pathophysiological parameters and lipid peroxidation in experimental rats. A positive control group orally treated with 4.5 ppm of fluoride was also included in the study. The assay of pathophysiological enzymes and histological observations made on the stomach and intestinal tissue have revealed the toxic effects of fluoride intoxication. The observed increase in the levels of thiobarbituric acid reactive substances (TBARS) both in plasma and in intestinal epithelium, with a concomitant decrease in both enzymatic and nonenzymatic antioxidants in the plasma of experimental rats, revealed that the altered antioxidant status during fluoride intoxication may be due to increased free radical generation.

  8. 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.

  9. Dental Fluorosis and Catalase Immunoreactivity of the Brain Tissues in Rats Exposed to High Fluoride Pre- and Postnatally.

    PubMed

    Güner, Şirin; Uyar-Bozkurt, Süheyla; Haznedaroğlu, Eda; Menteş, Ali

    2016-11-01

    This study evaluated dental fluorosis of the incisors and immunoreactivity in the brain tissues of rats given chronic fluoride doses pre- and postnatally. Female rats were given drinking water with 0, 30 or 100 ppm fluoride ad libitum throughout gestation and the nursing period. In addition, 63 male offspring were treated with the same water regimens as the mothers after weaning and were followed for 1, 3 or 5 months. The upper and lower incisors were collected, and all teeth were examined under a stereomicroscope and scored by two blinded examiners using a modified rodent enamel fluorosis index. Cortical, hippocampal and cerebellar brain samples were evaluated morphologically and immunohistochemically. All fluoride-treated pups were born with low body weight (p = 0.001). All animals from the fluoride groups had enamel fluorosis with defects of various degrees. The increase in the dental fluorosis scores in the fluoride treatment groups was significant (p < 0.01). The catalase immunoreactivity in the 30- and 100-ppm fluoride groups was significantly higher than that in the controls after 1, 3 and 5 months (p < 0.001). In conclusion, this study showed that rats with dental fluorosis had catalase immunoreactivity in the brain tissues, which may reflect the neurobehavioral toxicity of fluoride.

  10. Low-Cost, Robust, and Field Portable Smartphone Platform Photometric Sensor for Fluoride Level Detection in Drinking Water.

    PubMed

    Hussain, Iftak; Ahamad, Kamal Uddin; Nath, Pabitra

    2017-01-03

    Groundwater is the major source of drinking water for people living in rural areas of India. Pollutants such as fluoride in groundwater may be present in much higher concentration than the permissible limit. Fluoride does not give any visible coloration to water, and hence, no effort is made to remove or reduce the concentration of this chemical present in drinking water. This may lead to a serious health hazard for those people taking groundwater as their primary source of drinking water. Sophisticated laboratory grade tools such as ion selective electrodes (ISE) and portable spectrophotometers are commercially available for in-field detection of fluoride level in drinking water. However, such tools are generally expensive and require expertise to handle. In this paper, we demonstrate the working of a low cost, robust, and field portable smartphone platform fluoride sensor that can detect and analyze fluoride concentration level in drinking water. For development of the proposed sensor, we utilize the ambient light sensor (ALS) of the smartphone as light intensity detector and its LED flash light as an optical source. An android application "FSense" has been developed which can detect and analyze the fluoride concentration level in water samples. The custom developed application can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station. We envision that the proposed sensing technique could be useful for initiating a fluoride removal program undertaken by governmental and nongovernmental organizations here in India.

  11. Effects of fluoride treatment on phosphoric acid-etching in primary teeth: an AFM observation.

    PubMed

    Choi, Samjin; Rhee, Yeri; Park, Jeong-Hoon; Lee, Gi-Ja; Kim, Kyung-Sook; Park, Jae-Hong; Park, Young-Guk; Park, Hun-Kuk

    2010-07-01

    The aim of this study was to examine the effect of fluoride application on 37% phosphoric acid-etching by atomic force microscopy (AFM) in primary tooth samples based on a clinical protocol used in a pediatric dental hospital. Enamel samples were prepared from 36 exfoliated and non-carious primary teeth. Primary tooth samples were randomly assigned to one of the four groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. Group 1 received no fluoride application, Group 2 was pre-treated with fluoride and then received acid-etching 2 weeks later. One week separated the fluoride treatment and the acid-etching in Group 3, while Group 4 received acid-etching immediately after the fluoride treatment. The vestibular enamel surfaces of each primary tooth sample were scanned in air at a resolution of 512 x 512 pixels and a scan speed of 0.8 line/s. On the enamel surfaces of the primary teeth after APF pre-treatment, debris were observed although the teeth were smoother than they were prior to APF. As a result, it was concluded that APF treatment is responsible for decreased primary tooth surface roughness. The enamel surfaces etched for 20s showed that acid-etching was effective not only in removing scratches and debris, but also for evaluating enamel rod characteristics. Primary tooth enamel surfaces after etching showed minute structures caused by the decreased hydroxyapatite nanoparticle space, compared to those before etching. Also, acid-etching showed significantly increased roughness effects (p<0.0001, n=9). Finally, as more time elapsed after APF pre-treatment, the roughness was decreased to a lesser degree (p=0.005, n=9). We suggest that primary teeth etching 2 weeks after APF pre-treatment used clinically in pediatric hospitals may be effective to obtain properly etched enamel surfaces.

  12. 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

  13. Drinking water quality and fluoride concentration.

    PubMed

    Frazão, Paulo; Peres, Marco A; Cury, Jaime A

    2011-10-01

    This paper aimed to analyze the fluoride concentration in drinking water, taking into account the balance between the benefits and risks to health, in order to produce scientific backing for the updating of the Brazilian legislation. Systematic reviews studies, official documents and meteorological data were examined. The temperatures in Brazilian state capitals indicate that fluoride levels should be between 0.6 and 0.9 mg F/l in order to prevent dental caries. Natural fluoride concentration of 1.5 mg F/l is tolerated for consumption in Brazil if there is no technology with an acceptable cost-benefit ratio for adjusting/removing the excess. Daily intake of water with a fluoride concentration > 0.9 mg F/l presents a risk to the dentition among children under the age of eight years, and consumers should be explicitly informed of this risk. In view of the expansion of the Brazilian water fluoridation program to regions with a typically tropical climate, Ordinance 635/75 relating to fluoride added to the public water supply should be revised.

  14. Hydrogen Permeation Resistant Coatings

    SciTech Connect

    KORINKO, PAUL; ADAMS, THAD; CREECH, GREGGORY

    2005-06-15

    As the National Hydrogen Economy continues to develop and evolve the need for structural materials that can resist hydrogen assisted degradation will become critical. To date austenitic stainless steel materials have been shown to be mildly susceptible to hydrogen attack which results in lower mechanical and fracture strengths. As a result, hydrogen permeation barrier coatings may be applied to these ferrous alloys to retard hydrogen ingress. Hydrogen is known to be very mobile in materials of construction. In this study, the permeation resistance of bare stainless steel samples and coated stainless steel samples was tested. The permeation resistance was measured using a modular permeation rig using a pressure rise technique. The coating microstructure and permeation results will be discussed in this document as will some additional testing.

  15. 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.

  16. 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

  17. TD-DFT study on the excited-state proton transfer in the fluoride sensing of a turn-off type fluorescent chemosensor based on anthracene derivatives.

    PubMed

    Song, Ping; Ding, Jun-Xia; Chu, Tian-Shu

    2012-11-01

    The sensing mechanism for fluoride chemosensor based on anthracene structure has been investigated by DFT and TDDFT methods. The results show that the similar geometries in S(0) and S(1) states in the absence of the fluoride anion induce the local excited (LE) state over the anthracene moiety, which is responsible for the strong fluorescence. The fluorescence quenching phenomenon for F-coordinated complex can be explained by the photoinduced electron transfer (PET) process from benzylic amide to anthracene moiety. Moreover, the strong electronegativity for fluoride anion in the F-complex constructs the intermolecular hydrogen bond of N-H…F in the ground state. In contrast, the upper proton in the urea group close to phenyl group prefers to bind fluoride anion in S(1) state of the F-complex, and it presents excited-state proton transfer (ESPT) to form another hydrogen bond like N…H-F, which has been confirmed by natural bond orbital (NBO) analysis and the potential energy curve of S(1) state for the function of N-H bond. In this novel and efficient fluoride fluorescent chemosensor based on anthracene, the anthracene moiety is regarded as not only the fluorescent source, but the template for introducing the binding sites for fluoride anion.

  18. 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

  19. Fluoride - is it capable of fighting old and new dental diseases? An overview of existing fluoride compounds and their clinical applications.

    PubMed

    Brambilla, E

    2001-01-01

    Since researchers first became aware of the anticaries action of fluoride, they have been investigating the effect of this preventive agent in inhibiting or arresting caries development. Many forms of systemic or topical fluoride have been studied and tested for clinical application. Water, salt, milk fluoridation and the use of fluoride supplements were introduced for systemic fluoridation mainly using sodium fluoride. Solutions, gels, toothpastes and rinses of sodium fluoride, stannous fluoride, amine fluorides, acidulated phosphate fluoride and monofluorophosphate were used for topical fluoridation. More recently nonaqueous fluoride varnishes in an alcoholic solution of natural resins and difluorosilane agents in a polyurethane matrix were introduced. Although all of these fluoridation methods have a caries-preventive action, these benefits and the ease of application is variable. As fluoride is a key component of oral health promotion a coordinated approach on a community and individual basis seems to be needed to maximize the cost-benefit ratio of prevention.

  20. 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.

  1. Fluoride Selective Optical Sensor Based on Aluminum(III)-Octaethylporphyrin in Thin Polymeric Film: Further Characterization and Practical Application

    PubMed Central

    Badr, Ibrahim H. A.; Meyerhoff, Mark E.

    2008-01-01

    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-VIS 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 λmax of the porphyrin as well as 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 μM to 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

  2. 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.

  3. Widespread genetic switches and toxicity resistance proteins for fluoride.

    PubMed

    Baker, Jenny L; Sudarsan, Narasimhan; Weinberg, Zasha; Roth, Adam; Stockbridge, Randy B; Breaker, Ronald R

    2012-01-13

    Most riboswitches are metabolite-binding RNA structures located in bacterial messenger RNAs where they control gene expression. We have discovered a riboswitch class in many bacterial and archaeal species whose members are selectively triggered by fluoride but reject other small anions, including chloride. These fluoride riboswitches activate expression of genes that encode putative fluoride transporters, enzymes that are known to be inhibited by fluoride, and additional proteins of unknown function. Our findings indicate that most organisms are naturally exposed to toxic levels of fluoride and that many species use fluoride-sensing RNAs to control the expression of proteins that alleviate the deleterious effects of this anion.

  4. Mechanism of Electrophilic Fluorination with Pd(IV): Fluoride Capture and Subsequent Oxidative Fluoride Transfer†, ‡

    PubMed Central

    Brandt, Jochen R.; Lee, Eunsung; Boursalian, Gregory B.

    2013-01-01

    Electrophilic fluorinating reagents derived from fluoride are desirable for the synthesis of 18F-labeled molecules for positron emission tomography (PET). Here, we study the mechanism by which a Pd(IV)-complex captures fluoride and subsequently transfers it to nucleophiles. The intermediate Pd(IV)-F is formed with high rates even at the nano- to micromolar fluoride concentrations typical for radiosyntheses with 18F due to fast formation of an outer-sphere complex between fluoride and Pd(IV). The subsequent fluorine transfer from the Pd(IV)-F complex is proposed to proceed through an unusual SET/fluoride transfer/SET mechanism. The findings detailed in this manuscript provide a theoretical foundation suitable for addressing a more general approach for electrophilic fluorination with high specific activity 18F PET imaging. PMID:24376910

  5. Effects of Systemic Fluoride and in vitro Fluoride Treatment on Enamel Crystals

    PubMed Central

    Chen, H.; Czajka-Jakubowska, A.; Spencer, N.J.; Mansfield, J.F.; Robinson, C.; Clarkson, B.H.

    2008-01-01

    Systemically administered fluoride at a concentration of 75 ppm increases the surface roughness of developing enamel crystals in rats, which may be significant in advancing our understanding of the biological mechanism of fluorosis. Thus, the aim of this study was to investigate whether the increased surface roughness may be a result of surface restructuring by the direct action of fluoride at the crystal surface. We examined the fluoride dose-dependent roughening of enamel crystal surfaces in vivo, in the rat, and whether this roughening could be mimicked by the in vitro treatment of rat enamel crystals with neutral pH fluoride solutions. Our results showed that enamel crystal surface roughness increased after treatment with increasing fluoride ion concentrations, whether applied in vitro or administered systemically. This suggests a mechanism, alongside others, for the increased surface roughness of crystals in fluorotic enamel. PMID:17062747

  6. 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.

  7. 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 -.

  8. Facile nucleophilic fluorination reactions using tert-alcohols as a reaction medium: significantly enhanced reactivity of alkali metal fluorides and improved selectivity.

    PubMed

    Kim, Dong Wook; Jeong, Hwan-Jeong; Lim, Seok Tae; Sohn, Myung-Hee; Katzenellenbogen, John A; Chi, Dae Yoon

    2008-02-01

    Although protic solvents are generally not preferred for nucleophilic displacement reactions because of their partial positive charge and hydrogen-bonding capacity that solvate the nucleophile and reduce its reactivity, we recently reported a remarkably beneficial effect of using tertiary alcohols as a reaction media for nucleophilic fluorination with alkali metal fluorides, as well as fluorine-18 radiolabeling with [18F]fluoride ion for the preparation of PET radiopharmaceuticals. In this work, we investigate further the influence of the tert-alcohol reaction medium for nucleophilic fluorination with alkali metal fluorides by studying various interactions among tert-alcohols, the alkali metal fluoride (CsF), and the sulfonyloxy substrate. Factors such as hydrogen bonding between CsF and the tert-alcohol solvent, the formation of a tert-alcohol solvated fluoride, and hydrogen bonding between the sulfonate leaving group and the tert-alcohol appear to contribute to the dramatic increase in the rate of the nucleophilic fluorination reaction in the absence of any kind of catalyst. We found that fluorination of 1-(2-mesyloxyethyl)naphthalene (5) and N-5-bromopentanoyl-3,4-dimethoxyaniline (8) with Bu(4)N(+)F(-) in a tert-alcohol afforded the corresponding fluoro products in much higher yield than obtained by the conventional methods using dipolar aprotic solvents. The protic medium also suppresses formation of byproducts, such as alkenes, ethers, and cyclic adducts.

  9. Should the drinking water of Truro, Nova Scotia, be fluoridated? Water fluoridation in the 1990s.

    PubMed

    Ismail, A I; Shoveller, J; Langille, D; MacInnis, W A; McNally, M

    1993-06-01

    An epidemiological assessment of differences in caries and fluorosis prevalences between children in Truro (< 0.1 ppm) and Kentville (fluoridated at 1.1 ppm in 1991), Nova Scotia, Canada, was completed in 1991. Out of a total of 429 children, in grades 5 and 6, in the two towns in 1991, 219 (51%) were examined. Parents answered a self-administered questionnaire investigating the sources of drinking water used by the children since birth, residence history, use of fluoride supplements, dentifrices, and other fluoride products during the first 6 yr of the life. The examination criteria differentiated between non-cavitated and cavitated carious lesions. Dental fluorosis was measured using the TSIF index. Examiner agreement was excellent. Of the children examined, 80 (36.5%) drank water (fluoridated or non-fluoridated) from municipal water systems during the first 6 yr of life. The children were assigned into five groups based upon residence history and exposure to fluoridated water during the first 6 yr of life. The percentage difference in mean DMFS scores between children in the fluoridated and non-fluoridated groups is 17% (delta DMFS1 = 0.7) when non-cavitated carious lesions are included and 39% (delta DMFS2 = 1.1) when they are excluded. The differences are not statistically significant. The significant risk factors associated with the DMFS1 and DMFS2 scores identified by a stepwise multiple regression analysis are: education level of the father, gender, and number of years of reported use of toothpaste during the first 6 yr of life. Dental fluorosis (mainly TSIF score of 1) was present in 41.5% and 69.2% of the children in the non-fluoridated and fluoridated groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Radiation effects in fluoride glasses

    NASA Astrophysics Data System (ADS)

    Tanimura, K.; Sibley, W. A.; Suscavage, M.; Drexhage, M.

    1985-12-01

    Radiation-induced defects in Zr-based fluoride glasses have been characterized using optical absorption and electron spin resonance (ESR) techniques. The optical absorption bands due to interstitial fluorine atoms, the F2(-), FC1(-), C12(-) centers, and Zr(3+) centers have been identified by correlating optical absorption and ESR measurements. Polarized bleaching experiments indicate that the hole-type centers, and the Zr(3+) centers have anisotropic defect configurations. X-ray excitation at 14 K generates a broad, asymmetric emission band at 337 nm (3.68 eV), which is assigned to a localized-excited state similar to that for self-trapped excitons in halide crystals. The intensity of the X-ray induced emission provides further evidence that radiolysis defect production occurs in this material. The optical tail of the radiation-induced Zr(3+) absorption affects infrared transmission. Evidence is presented that the CC14 reactive-atmosphere process introduces a significant amount of Cl(-) (about 5 percent) in the glass.

  11. Synthesis and characterizations of a fluoride-releasing dental restorative material.

    PubMed

    Khan, Abdul Samad; Aamer, Sidra; Chaudhry, Aqif Anwar; Wong, Ferranti S L; Ur Rehman, Ihtesham

    2013-08-01

    The aim was to develop an obturating material which has the tendency to release fluoride and minimize interfaces with tooth. Nano-fluorapatite (nFA) powder was synthesized by sol-gel. The composite based on polyurethane (PU) was obtained by chemically binding the nFA (10, 15, 20%wt/wt) to the diisocyanate component by utilizing in-situ polymerization. The procedure involved stepwise addition of monomeric units of PU, and optimizing the reagent concentrations to synthesize composite. The structural, phase and morphological analysis of nFA was evaluated. The structural, fluoride release and in-vitro adhesion analysis with tooth structure of PU/nFA was conducted. For fluoride release analysis the samples were stored in artificial saliva and deionized water for periodical time intervals. Bond strength of composites was analyzed by push-out test. Chemical linkage was achieved between PU and nFA without intermediate coupling agent. The insignificant difference of fluoride release pattern was observed in artificial saliva and (p≥0.05) deionized water. The PU/nFA composite provided sustained release of fluoride over a long period of time. The composite showed more adhesion toward tooth structure with the increase in concentration of nFA. Bond strength of composite was in accordance with root canal filling material, hence, the material with anti-cariogenic properties can be used as an obturating material.

  12. Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore

    NASA Astrophysics Data System (ADS)

    Kebede, Beekam; Beyene, Abebe; Fufa, Fekadu; Megersa, Moa; Behm, Michael

    2016-03-01

    High concentrations of fluoride in drinking water is a public health concern globally and of critical importance in the Rift Valley region. As a low-cost water treatment option, the defluoridation capacity of locally available iron ore was investigated. Residence time, pH, agitation rate, particle size of the adsorbent, sorbent dose, initial fluoride concentration and the effect of co-existing anions were assessed. The sorption kinetics was found to follow pseudo-first-order rate and the experimental equilibrium sorption data fitted reasonably well to the Freundlich model. The sorption capacity of iron ore for fluoride was 1.72 mg/g and the equilibrium was attained after 120 min at the optimum pH of 6. The sorption study was also carried out at natural pH conditions using natural ground water samples and the fluoride level was reduced from 14.22 to 1.17 mg/L (below the WHO maximum permissible limit). Overall, we concluded that iron ore can be used in water treatment for fluoride removal in the Rift Valley region and beyond.

  13. Synthesis, characterization, and evaluation of simple aluminum-based adsorbents for fluoride removal from drinking water.

    PubMed

    Du, Junyi; Sabatini, David A; Butler, Elizabeth C

    2014-04-01

    Simple aluminum (hydr)oxides and layered double hydroxides were synthesized using common chemicals and equipment by varying synthesis temperature, concentrations of extra sulfate and citrate, and metal oxide amendments. Aluminum (hydr)oxide samples were aged at either 25 or 200°C during synthesis and, in some cases, calcined at 600 °C. Despite yielding increased crystallinity and mineral phase changes, higher temperatures had a generally negative effect on fluoride adsorption. Addition of extra sulfate during synthesis of aluminum (hydr)oxides led to significantly higher fluoride adsorption capacity compared to aluminum (hydr)oxides prepared with extra citrate or no extra ligands. X-ray diffraction results suggest that extra sulfate led to the formation of both pseudoboehmite (γ-AlOOH) and basaluminite (Al4SO4(OH)10⋅4H2O) at 200 °C; energy dispersive X-ray spectroscopy confirmed the presence of sulfur in this solid. Treatment of aluminum (hydr)oxides with magnesium, manganese, and iron oxides did not significantly impact fluoride adsorption. While layered double hydroxides exhibited high maximum fluoride adsorption capacities, their adsorption capacities at dissolved fluoride concentrations close to the World Health Organization drinking water guideline of 1.5 mg L(-1) were much lower than those for the aluminum (hydr)oxides.

  14. A coumarin based ICT probe for fluoride in aqueous medium with its real application.

    PubMed

    Upadhyay, K K; Mishra, Rakesh K; Kumar, Virendra; Chowdhury, P K Roy

    2010-06-30

    A new coumarin based hydrazone (receptor 1) synthesized by modifying one of our earlier reported receptor detected fluoride ion selectively through naked eye in aq. DMSO (5:95, v/v). It was also able to detect fluoride through naked eye in a toothpaste sample. The addition of 1 equiv. of fluoride as its tetrabutylammonium salt to the 5 x 10(-5) M aq. DMSO solution of the receptor 1 produced red color while the similar addition of acetate produced faint pink color. The dihydrogenphosphate and a variety of other anions were not able to produce any significant color change with receptor 1 under similar experimental conditions. The corresponding UV-vis measurements showed a bathochromic shifting of 455 nm band of receptor 1 to 514 and 484 nm for fluoride and acetate, respectively. The non-linear fittings of corresponding UV-vis titration data in 1:1 binding equation yielded association constants in 10(5):1 ratio for fluoride and acetate, respectively. The (1)H NMR titrations studies shade further light on their mode of binding with receptor 1. The quantum mechanical calculations through time dependant density functional theory (TD-DFT) using basis set b3lyp/6-311g** supported our experimental findings nicely.

  15. Association of hydrogeological factors in temporal variations of fluoride concentration in a crystalline aquifer in India

    NASA Astrophysics Data System (ADS)

    Sreedevi, P. D.; Ahmed, S.; Made, B.; Ledoux, E.; Gandolfi, J. M.

    2006-05-01

    The major part of groundwater in India is found in granitic aquifers. Fluoride in groundwater from a crystalline aquifer in a semi-arid region of granitic rocks in India, known as Maheshwaram watershed, was analyzed for spatial and temporal variability during 1999-2002 to assess the effect of hydrogeological factors on fluoride concentration. Samples were collected from 32 representative wells in the area for the pre- and post-monsoon seasons and analyzed for F content. The CHESS computer program was used to calculate ionic activities of aqueous species and the mineral saturation index (SI) for calcite and fluorite. The GARDENIA computer program was used to calculate the recharge values in the study area. The influences of dissolution kinetics of fluoride minerals and recharge from rainfall on fluoride concentration were of interest and results clearly indicate that fluoride content in groundwater depends on the interaction period of groundwater with host rock. Results could also be utilized for designing remedial measures particularly with dilution method in an optimal way.

  16. Antibacterial Properties of Calcium Fluoride-Based Composite Materials: In Vitro Study

    PubMed Central

    Zarzycka, Beata; Grzegorczyk, Janina; Sokołowski, Krzysztof; Półtorak, Konrad; Sokołowski, Jerzy

    2016-01-01

    The aim of the study was to evaluate antibacterial activity of composite materials modified with calcium fluoride against cariogenic bacteria S. mutans and L. acidophilus. One commercially available conventional light-curing composite material containing fluoride ions (F2) and two commercially available flowable light-curing composite materials (Flow Art and X-Flow) modified with 1.5, 2.5, and 5.0 wt% anhydrous calcium fluoride addition were used in the study. Composite material samples were incubated in 0.95% NaCl at 35°C for 3 days; then dilution series of S. mutans and L. acidophilus strains were made from the eluates. Bacteria dilutions were cultivated on media afterwards. Colony-forming unit per 1 mL of solution (CFU/mL) was calculated. Composite materials modified with calcium fluoride highly reduced (p < 0.001) bacteria growth compared to commercially available composite materials containing fluoride compounds. The greatest reduction in bacteria growth was observed for composite materials modified with 1.5% wt. CaF2. All three tested composite materials showed statistically greater antibacterial activity against L. acidophilus than against S. mutans. PMID:28053976

  17. New Autoinductive Cascade for the Optical Sensing of Fluoride: Application in the Detection of Phosphoryl Fluoride Nerve Agents.

    PubMed

    Sun, Xiaolong; Dahlhauser, Samuel D; Anslyn, Eric V

    2017-04-05

    A new autoinductive cascade employing benzoyl fluoride as a latent source of fluoride is reported for signal amplification and optical detection of fluoride. The autoinduction leads to a maximum 4-fold signal enhancement for each fluoride generated, as well as a self-propagating cycle that generates three fluorophores for each single fluoride released. A two-step integrated protocol creates a more rapid autoinductive cascade than previously reported, as well as a highly sensitive diagnostic assay for the ultratrace quantitation of a phosphoryl fluoride nerve agent surrogate.

  18. Zero-gravity growth of a sodium chloride-lithium fluoride eutectic mixture

    NASA Technical Reports Server (NTRS)

    Yue, A. S.; Yeh, C. W.; Yue, B. K.

    1982-01-01

    Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on Earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convective current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and Earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.

  19. Effect of fluoride on the morphology of calcium phosphate crystals grown on acid-etched human enamel.

    PubMed

    Fan, Y; Sun, Z; Moradian-Oldak, J

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2-10 microm wide) were formed. With 1-10 mg/l fluoride, arrays of denser needle-like nanocrystals (20-30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro.

  20. Effect of Fluoride on the Morphology of Calcium Phosphate Crystals Grown on Acid-Etched Human Enamel

    PubMed Central

    Fan, Y.; Sun, Z.; Moradian-Oldak, J.

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2–10 μm wide) were formed. With 1–10 mg/l fluoride, arrays of denser needle-like nanocrystals (20–30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro. PMID:19321991

  1. Stability of ammonium fluoride-treated Si(100)

    NASA Astrophysics Data System (ADS)

    Houston, Michael R.; Maboudian, Roya

    1995-09-01

    X-ray photoelectron spectroscopy (XPS) and contact angle analyses have been employed to investigate the chemical stability of silicon surfaces treated by an ammonium fluoride (NH4F) solution. Consistent with earlier results [Dumas and Chabal, Chem. Phys. Lett. 181, 537 (1991)], it is found that an NH4F final etch produces surfaces exhibiting lower oxygen and carbon contamination levels in comparison to the surfaces obtained with the traditional HF or buffered HF (BHF) etch. In conjunction with lower contamination levels, surfaces treated in ammonium fluoride show higher contact angles with water, indicating lower surface free energies. The Si-H surfaces produced by the ammonium fluoride etch were found to remain hydrophobic for weeks in air and showed no signs of oxidation for several days. After an induction period of about one week in air, oxidation began to occur in a more rapid fashion. The stability of the Si-H surfaces in water was also investigated, and it was found that the oxygen contamination levels measured by x-ray photoelectron spectroscopy were extremely sensitive to the final rinse time. An induction period of approximately one hour in water existed before any signs of oxidation were evident. Despite the fact that the NH4F-treated samples were initially cleaner than the HF-treated samples, both of these surfaces showed similar temporal behavior in air and water. We attribute this finding to the surface topographies produced by these treatments, as well as to the extreme sensitivity of the results to such factors as water rinse time.

  2. Observations of the freeze/thaw performance of lithium fluoride by motion picture photography

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Perry, W. D.

    1991-01-01

    To gain direct observation of the molten salt phase change, a novel containerless technique was developed where the high surface tension of lithium fluoride was used to suspend a bead of the molten salt inside a specially designed wire cage. By varying the current passing through the wire, the cage also served as a variable heat source. In this way, the freeze/thaw performance of the lithium fluoride could be photographed by motion picture photography without the influence of container walls. The motion picture photography of the lithium fluoride sample revealed several zones during the phase change, a solid zone and a liquid zone, as expected, and a slush zone that was predicted by thermal analysis modeling.

  3. A Comparative Evaluation of the Amount of Fluoride Release and Re-Release after Recharging from Aesthetic Restorative Materials: An in vitro Study

    PubMed Central

    Bansal, Ruchika

    2015-01-01

    Aim To measure the amount of fluoride released and re released after recharging from various restorative materials: Conventional Glass Ionomer Cement (Fuji II), Light Cure Resin Modified GIC (Fuji II LC), Giomer (Beautifil II), Compomer (Dyract). Materials and Methods Fifteen cylindrical specimens were prepared from each material. The specimens were immersed in 20 ml of deionized water. The amount of released fluoride was measured during the 1st day, 7th day and on the day15 by using specific fluoride electrode and an ion-analyser. After 15 days each material was divided into three Sub Groups of five samples each. Sub Group A served as control, Sub Group B was exposed to 2% NaF solution, Sub Group C to 1000ppm F toothpaste. The amount of fluoride re-released was measured during the 1st day, 7th day and on the day15 by using specific fluoride electrode and an ion-analyser. The results were statistically analysed using analysis of variance (one-way ANOVA) and Tukey Kramer multiple comparison tests (p≤0.05). Results Independent of the observation time period of the study the Conventional GIC released the highest amount of fluoride followed by RMGIC, Giomer and Compomer. The initial burst effect was seen with GIC’S but not with Giomer and Compomer. After topical fluoride application fluoride re release was highest in Sub Group B and GIC had a greater recharging ability followed by RMGIC, Giomer and Compomer. The fluoride re release was greatest on 1st day followed by rapid return to near exposure levels. Conclusion From the study it was concluded that, the initial Fluoride release was highest from Conventional GIC followed by Resin Modified GIC, Giomer and Compomer. The Fluoride re release was high when recharging with professional regime (2% NaF) as compared to home regime (Toothpaste). Conventional GIC had a greater recharging ability followed by Resin Modified GIC, Giomer and Compomer. PMID:26436037

  4. Application of crude extract of kohlrabi (Brassica oleracea gongylodes) as a rich source of peroxidase in the spectrofluorometric determination of hydrogen peroxide in honey samples.

    PubMed

    Manzoori, Jamshid L; Amjadi, Mohammad; Orooji, Maghsood

    2006-09-01

    Crude extract of kohlrabi (Brassica oleracea gongylodes) was prepared by a simple procedure and its enzymatic activity and total protein concentration were determined. It was found that this crude extract is a rich source of peroxidase (POx) and has high specific activity. Cross-linked polyvinylpyrrolidone was used as a stabilizer in the preparation of the crude extract. The POx activity of kohlrabi crude extract did not vary for at least 2 months when deoxygenated and stored at 4 degrees C. This extract was applied for the spectrofluorometric determination of hydrogen peroxide using homovanillic acid as a fluorogenic substrate. POx catalyzes the hydrogen peroxide oxidation of homovanillic acid to produce a dimer which shows strong fluorescence at 420 nm with excitation at 312 nm. In the optimum conditions, the calibration graph for hydrogen peroxide was linear up to 190 ng mL(-1), with a detection limit of 4.4 ng mL(-1). The relative standard deviation (RSD) was 1.48% for 50 ng mL(-1) hydrogen peroxide. The proposed method was successfully applied to the determination of hydrogen peroxide in honey. The concentration-time profile of H2O2 produced upon dilution of honey was studied and H2O2 contents of some different honeys from various areas of Iran were determined.

  5. Optical fluoride sensor based on monomer-dimer equilibrium of scandium(III)-octaethylporphyrin in a plasticized polymeric film.

    PubMed

    Kang, Youngjea; Kampf, Jeff W; Meyerhoff, Mark E

    2007-08-29

    A fluoride-selective optical sensor based on scandium(III)-octaethylporphyrin (Sc(III)OEP) as an ionophore within a plasticized PVC film is described. The presence of fluoride ion in the aqueous sample phase increases the formation of a difluoro-bridged Sc(III)OEP dimer species in the polymer film. The ability of the Sc(III) porphyrin to form the dimeric structure in the presence of fluoride is confirmed by UV-vis spectroscopy and X-ray crystallography. For more practical sensing applications, a pH chromoionophore (ETH 7075) is added to the plasticized PVC film along with Sc(III)OEP and the observed optical response is based on coextraction of protons with sample phase fluoride to create the dimeric porphyrin and a protonated chromoionophore species. The selectivity pattern observed is F- > ClO4(-), SCN-, NO3(-) > Br-, Cl-. Only organic salicylate is a significant interferent. Fast and reversible fluoride response is observed over the range of 10(-4) to 10(-2) M fluoride, allowing use of the sensing film in a waveguide configuration for flow-injection measurements.

  6. Vitamin A deficiency: An oxidative stress marker in sodium fluoride (NaF) induced oxidative damage in developing rat brain.

    PubMed

    Banala, Rajkiran Reddy; Karnati, Pratap Reddy

    2015-12-01

    Fluoride induced oxidative stress through depletion in levels of various anti-oxidants such as glutathione, superoxide dismutase (SOD), fat soluble vitamins (D and E) with increased levels of lipid peroxidation (LPO) and fluoride aggravate the damage in rodents as well as in humans. Vitamins A, a fat soluble vitamin possess antioxidant property which plays a significant role in scavenging the free radicals species similar to vitamin D and E. Vitamin A is involved in neural tissue development and plasticity. The growing evidence about vitamin A being antioxidant in different biological reactions formed the basis to determine the effect of fluoride on its levels. The present study was conducted in Wistar rat pups. The pregnant wistar rats were dosed with 20 ppm sodium fluoride (NaF) from day one of pregnancy till the pups were aged day 30. The serum was collected from developing rat pups on regular intervals (14th, 21st, 30th day) and vitamin A levels were analyzed by High performance liquid chromatography (HPLC). Body weights, Behavioural studies and spectrophotometric estimation of SOD, LPO in brain lysates were also performed. The results showed significant decrease (p<0.001) in vitamin A in fluoride induced samples in comparison to the control samples suggesting that decreased levels of vitamin A can be used as another marker in fluoride induced toxicity studies.

  7. The Northland fluoridation advocacy programme: an evaluation.

    PubMed

    Gowda, Sunitha; Thomas, David R

    2008-12-01

    On 20 July 2006, the Far North District Council resolved to fluoridate Kaitaia and Kaikohe. This was the first such initiative by any Territorial Local Authority (TLA) in New Zealand for 23 years, and resulted from a fluoridation advocacy programme. This paper describes the programme implementation, assesses its consistency with the principles of the Treaty of Waitangi, and critically examines the collaboration between the fluoride advocate and the key stakeholders. Process evaluation identified three main categories of programme implementation: policy advocacy, community action projects, and media advocacy. The collaboration of iwi, Maori health providers and the community suggests that the programme was consistent with the principles (partnership, participation and protection) ofthe Treaty ofWaitangi. Media advocacy played an important role in reflecting and engaging community views on fluoridation, and it influenced decision-making by the Far North District Council. The simultaneous, combined 'top-down and bottom-up' approach was an effective and successful strategy for fluoridation advocacy in the community. Less integrated approaches implemented on their own (such as the 'top down' approach in Whangarei and the 'bottom-up' approach in Dargaville) were not effective.

  8. The fin whale, a marine top consumer, exposes strengths and weaknesses of the use of fluoride as ecological tracer.

    PubMed

    Vighi, Morgana; García-Nisa, I; Borrell, A; Aguilar, A

    2015-05-01

    Fluoride is retained in bone tissues of animals and its availability in the environment varies between regions according to natural and anthropogenic sources. These properties suggest this element as a suitable tracer of origin, distribution or movements of animals. In marine environments, krill builds-up fluoride concentrations that are transferred to its predators. In this study we examine the ability of bone fluoride concentrations to discriminate two separate populations of a krill consumer, the fin whale. Background levels of the sampling areas (Western Iceland and North-Western Spain) were determined through the analysis of krill samples. As expected, due to the high load of volcanic-derived fluoride in Icelandic waters, krill from W Iceland showed much higher fluoride concentrations than that from NW Spain. Concentrations in whales' bone were correlated with sex and age, increasing linearly with age in females and showing significantly lower values and a different age-related pattern of accumulation in males. Fluoride concentrations in whales' bone were much higher than in krill, indicating accumulation of the element but, rather unexpectedly, the area of origin had no influence on concentrations. This apparent contradiction may be explained either by the integration in bone of food consumed in other areas, or by the activation of homeostatic responses at very high levels of fluoride exposure. It is concluded that fluoride can be a useful tracer only if age and sex data are integrated into the analysis, year-round information on diet is available and/or the investigated population is exposed to mild levels of this element.

  9. Dental fluorosis, fluoride in urine, and nutritional status in adolescent students living in the rural areas of Guanajuato, Mexico

    PubMed Central

    del Carmen, Aguilar-Díaz Fatima; Javier, de la Fuente-Hernández; Aline, Cintra-Viveiro Cristina

    2016-01-01

    Objective: The aim of this study was to assess urine fluoride concentration, nutritional status, and dental fluorosis in adolescent students living in the rural areas of Guanajuato, Mexico. Materials and Methods: A cross-sectional study was conducted including participants aged 11–20 years. The presence and severity of dental fluorosis was registered according to the Thylstrup and Fejerskov index (TFI) criteria. Anthropometric measures were also recorded. Urine sample of the first morning spot was recollected to assess urine fluoride concentration by using the potentiometric method with an ion-selective electrode. Water samples were also recollected and analyzed. Bivariate tests were performed to compare urine fluoride concentration according to different variables such as sex, body mass index, and TFI. Nonparametric tests were used. A logistic regression model was performed (SPSS® 21.0). Results: This study included 307 participants with a mean age of 15.6 ± 1.6; 62.5% of the participants showed normal weight. A total of 91.9% of the participants had dental fluorosis, and 61.6% had TFI > 4. Mean fluoride content in urine ranged between 0.5 and 6.65 mg/L, with a mean of 1.27 ± 1.2 mg/L. Underweight children showed greater urine fluoride concentration. The increment of urine fluoride was a related (OR = 1.40) to having severe dental fluorosis. Conclusions: Most of the studied population had moderate or severe dental fluorosis. Urine fluoride concentration was related to fluorosis severity and nutritional status. Underweight children showed greater urine fluoride concentration as well as severe dental fluorosis. PMID:28032042

  10. Hydrogenation apparatus

    DOEpatents

    Friedman, Joseph [Encino, CA; Oberg, Carl L [Canoga Park, CA; Russell, Larry H [Agoura, CA

    1981-01-01

    Hydrogenation reaction apparatus comprising a housing having walls which define a reaction zone and conduits for introducing streams of hydrogen and oxygen into the reaction zone, the oxygen being introduced into a central portion of the hydrogen stream to maintain a boundary layer of hydrogen along the walls of the reaction zone. A portion of the hydrogen and all of the oxygen react to produce a heated gas stream having a temperature within the range of from 1100.degree. to 1900.degree. C., while the boundary layer of hydrogen maintains the wall temperature at a substantially lower temperature. The heated gas stream is introduced into a hydrogenation reaction zone and provides the source of heat and hydrogen for a hydrogenation reaction. There also is provided means for quenching the products of the hydrogenation reaction. The present invention is particularly suitable for the hydrogenation of low-value solid carbonaceous materials to provide high yields of more valuable liquid and gaseous products.

  11. Measurement of internal substrate binding in dehaloperoxidase-hemoglobin by competition with the heme-fluoride binding equilibrium.

    PubMed

    Zhao, Jing; Moretto, Justin; Le, Peter; Franzen, Stefan

    2015-02-19

    The application of fluoride anion as a probe for investigating the internal substrate binding has been developed and applied to dehaloperoxidase-hemoglobin (DHP) from Amphitrite ornata. By applying the fluoride titration strategy using UV-vis spectroscopy, we have studied series of halogenated phenols, other substituted phenols, halogenated indoles, and several natural amino acids that bind internally (and noncovalently) in the distal binding pocket of the heme. This approach has identified 2,4-dibromophenol (2,4-DBP) as the tightest binding substrate discovered thus far, with approximately 20-fold tighter binding affinity than that of 4-bromophenol (4-BP), a known internally binding inhibitor in DHP. Combined with resonance Raman spectroscopy, we have confirmed that competitive binding equilibria exist between fluoride anion and internally bound molecules. We have further investigated the hydrogen bonding network of the active site of DHP that stabilizes the exogenous fluoride ligand. These measurements demonstrate a general method for determination of differences in substrate binding affinity based on detection of a competitive fluoride binding equilibrium. The significance of the binding that 2,4-dibromophenol binds more tightly than any other substrate is evident when the structural and mechanistic data are taken into consideration.

  12. Removing Fluoride Ions with Continously Fed Activated Alumina.

    ERIC Educational Resources Information Center

    Wu, Yeun C.; Itemaking, Isara Cholapranee

    1979-01-01

    Discussed is the mathematical basis for determining fluoride removal during water treatment with activated alumina. The study indicates that decreasing particle size decreases the pore diffusion effect and increases fluoride removal. (AS)

  13. Gramicidin D enhances the antibacterial activity of fluoride.

    PubMed

    Nelson, James W; Zhou, Zhiyuan; Breaker, Ronald R

    2014-07-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in Bacillus subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride.

  14. Global water fluoridation: what is holding us back?

    PubMed

    Botchey, Sally-Ann; Ouyang, Jing; Vivekanantham, Sayinthen

    2015-01-01

    Artificial water fluoridation was introduced more than 60 y ago as a public health intervention to control dental caries. Despite wide recommendations for its use from the World Health Organization (WHO) and studies showing the benefits of water fluoridation, many countries have opted out. Currently, only 25 countries, including the United Kingdom, the United States, and Australia have schemes for artificial water fluoridation. The issues faced in efforts to promote the global uptake of water fluoridation and the factors that affect the decision to implement it are unique in both developed and developing countries and must be explored. This article addresses the benefits and challenges of artificial water fluoridation. Further, it tackles the complexities faced with uptake of water fluoridation globally, such as ethical and political controversies and the use of alternative fluoride therapies. Potential future strategies to encourage the uptake of artificial water fluoridation are also discussed.

  15. Hydrogeochemical characterization of fluoride rich groundwater of Wailpalli watershed, Nalgonda District, Andhra Pradesh, India.

    PubMed

    Reddy, A G S; Reddy, D V; Rao, P N; Prasad, K Maruthy

    2010-12-01

    The groundwater of Nalgonda district is well known for its very high fluoride content for the past five decades. Many researchers have contributed their scientific knowledge to unravel causes for fluoride enrichment of groundwater. In the present paper, an attempt has been made to relate the high fluoride content in the groundwater to hydrogeochemical characterization of the water in a fracture hard rock terrain--the Wailpally watershed. Groundwater samples collected from all the major geomorphic units in pre- and post-monsoon seasons were analyzed for its major ion constituents such as Ca(2+), Mg(2+), Na(+), K(+), CO3-, HCO3-, Cl(-), SO4(-2), NO3-, and F(-). The groundwaters in the watershed have the average fluoride content of 2.79 mg/l in pre-monsoon and 2.83 mg/l in post-monsoon. Fluoride concentration in groundwater does not show perceptible change neither with time nor in space. The ionic dominance pattern is in the order of Na(+) > Ca(2+) > Mg(2+) > K(-) among cations and HCO3- Cl(-) > SO4(-2) NO3- F(-) among anions in pre-monsoon. In post-monsoon, Mg replaces Ca(2+) and NO3- takes the place of SO4(-2). The Modified Piper diagram reflect that the water belong to Ca(+2)-Mg(+2)-HCO3- to Na(+)-HCO3- facies. Negative chloralkali indices in both the seasons prove that ion exchange between Na(+) and K(+) in aquatic solution took place with Ca(+2) and Mg(+2) of host rock. The interpretation of plots for different major ions and molar ratios suggest that weathering of silicate rocks and water-rock interaction is responsible for major ion chemistry of groundwater in Wailpally watershed. Chemical characteristics and evolution of this fluoride-contaminated groundwater is akin to normal waters of other hard rock terrain; hence, it can be concluded that aquifer material play an important role in the contribution of fluoride in to the accompanying water. High fluoride content in groundwater can be attributed to the continuous water-rock interaction during the

  16. Risk Assessment Study of Fluoride Salts: Probability-Impact Matrix of Renal and Hepatic Toxicity Markers.

    PubMed

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

    2016-09-01

    The present risk assessment study of fluoride salts was conducted by oral administration of three different doses of sodium and potassium fluorides (NaF, KF) and zinc fluoride tetrahydrate (ZnF2 •4H2O) to male Wistar rats. The rats were divided into control and nine experimental groups, to which oral injections of 0.5 mL distilled water and 0.5 mL of fluoride solutions, respectively, were given. The dosage of fluoride compounds was adjusted to contain 2.1 mg (low-dose group, LG), 4.3 mg (mid-dose group, MG), and 5.4 mg fluoride per 200 g rat body weight (high-dose group, HG) corresponding to 5, 10, and 12.5 % of LD50 values for NaF. The 24-h urine volume, N-acetyl-β-D-glucosaminidase (NAG) and creatinine clearance (Ccr) were measured as markers of possible acute renal impact. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined in serum samples as markers of acute hepatic impact. The levels of serum and urinary fluoride were determined to evaluate fluoride bioavailability. The results reveal that higher doses of NaF, KF, and ZnF2 induced renal damage as indicated by higher urinary NAG (p < 0.05 with ≥90th percentile of control). High doses of ZnF2 also induced a significant Ccr decrease (p < 0.05 with ≤10th percentile of control). Low doses of NaF and mid-doses of ZnF2 induced polyuria (p < 0.05 with ≥90th percentile of control) while medium doses of NaF and low doses of KF also induced liver damage, as indicated by a high level of AST (p < 0.05 with ≥90th percentile of control). These findings suggest that oral administration of fluoride is a potential, dose-dependent risk factor of renal tubular damage.

  17. The effects of sodium fluoride and stannous fluoride on the surface roughness of intraoral magnet systems.

    PubMed

    Obatake, R M; Collard, S M; Martin, J; Ladd, G D

    1991-10-01

    Four types of intraoral magnets used for retention of overdentures and maxillofacial prostheses were exposed in vitro to SnF2 and NaF to determine the effects of fluoride rinses on surface roughness. The surface roughness (Ra) was measured, after simulated 1, 2, and 5 years' clinical exposure to fluoride (31, 62, and 155 hours). The mean change in Ra was calculated for each period of simulated exposure to fluoride for each magnet type. Two-way ANOVA was used to compare mean change in Ra between magnets within fluorides, and between fluorides within magnets. Paired t tests were used to compare mean change in Ra within fluorides within magnets. The mean change in Ra increased for all magnets after simulated 1, 2, and 5 years of exposure to SnF2 and NaF (p less than 0.03). Using the change in Ra as an indicator for corrosion, PdCo encapsulated SmCo5 magnets and their keepers demonstrated the least corrosion with either fluoride.

  18. Method for the analysis of total fluoride in fluoride-releasing dental varnishes.

    PubMed

    Carey, C M; Coleman, S S

    2014-01-01

    Today's fluoride-releasing varnishes (F-varnish) contain a wide variety of ingredients which present analytical challenges for measuring their total fluoride content. This study reports improved methods to measure fluoride content in F-varnishes. Six different commercially available F-varnishes that contain difluorosilane (0.1% F) or NaF (2.26% F) alone or in combination with calcium-phosphates were analyzed. In a vial, 1-3 drops (0.05-0.15 g) of varnish product was dispensed, dissolved in chloroform, equilibrated in TISAB and analyzed via fluoride ion-selective electrode. The average weight percentage of fluoride for all F-varnishes containing NaF ranged from 2.03 to 2.24% F, which is within 90% of the declared label concentration of 2.26% F. Analysis of the difluorosilane-containing product required an additional hydrolysis step. ANOVA found no significant difference between the 5% NaF varnishes at p < 0.05. This method for fluoride analysis yields reliable and reproducible results and can be used for a wide variety of F-varnishes. The standard uncertainty for this method is ±4%. This method may become the basis for national and international standards that ensure the F-varnish products used in clinical practice have the fluoride content declared in the product literature.

  19. Method for the Analysis of Total Fluoride in Fluoride-Releasing Dental Varnishes

    PubMed Central

    Carey, C.M.; Coleman, S.S.

    2016-01-01

    Today’s fluoride-releasing varnishes (F-varnish) contain a wide variety of ingredients which present analytical challenges for measuring their total fluoride content. This study reports improved methods to measure fluoride content in F-varnishes. Six different commercially available F-varnishes that contain difluorosilane (0.1% F) or NaF (2.26% F) alone or in combination with calcium-phosphates were analyzed. In a vial, 1–3 drops (0.05–0.15 g) of varnish product was dispensed, dissolved in chloroform, equilibrated in TISAB and analyzed via fluoride ion-selective electrode. The average weight percentage of fluoride for all F-varnishes containing NaF ranged from 2.03 to 2.24% F, which is within 90% of the declared label concentration of 2.26% F. Analysis of the difluorosilane-containing product required an additional hydrolysis step. ANOVA found no significant difference between the 5% NaF varnishes at p < 0.05. This method for fluoride analysis yields reliable and reproducible results and can be used for a wide variety of F-varnishes. The standard uncertainty for this method is ±4%. This method may become the basis for national and international standards that ensure the F-varnish products used in clinical practice have the fluoride content declared in the product literature. PMID:24557443

  20. Estimated fluoride doses from toothpastes should be based on total soluble fluoride.

    PubMed

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

    2013-11-01

    The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF) rather than levels of bioavailable fluoride (total soluble fluoride-TSF) in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80) or children's toothpaste (n = 78)). The estimated dose (mg F/day/Kg of body weight) of TF or TSF ingested was calculated from the chemical analysis of the toothpastes. Although the ingested dose of TF from the family toothpastes was higher than that from the children's toothpastes (0.074 ± 0.007 and 0.039 ± 0.003 mg F/day/Kg, respectively; p < 0.05), no difference between types of toothpaste was found regarding the ingested dose based on TSF (0.039 ± 0.005 and 0.039 ± 0.005 mg F/day/Kg, respectively; p > 0.05). The fluoride dose ingested by children from toothpastes may be overestimated if based on the TF of the product. This finding suggests that the ingested dose should be calculated based on TSF. Dose of TSF ingested by children is similar whether family or children's toothpaste is used.

  1. The future of fluorides and other protective agents in erosion prevention.

    PubMed

    Lussi, Adrian; Carvalho, Thiago Saads

    2015-01-01

    The effectiveness of fluoride in caries prevention has been convincingly proven. In recent years, researchers have investigated the preventive effects of different fluoride formulations on erosive tooth wear with positive results, but their action on caries and erosion prevention must be based on different requirements, because there is no sheltered area in the erosive process as there is in the subsurface carious lesions. Thus, any protective mechanism from fluoride concerning erosion is limited to the surface or the near surface layer of enamel. However, reports on other protective agents show superior preventive results. The mechanism of action of tin-containing products is related to tin deposition onto the tooth surface, as well as the incorporation of tin into the near-surface layer of enamel. These tin-rich deposits are less susceptible to dissolution and may result in enhanced protection of the underlying tooth. Titanium tetrafluoride forms a protective layer on the tooth surface. It is believed that this layer is made up of hydrated hydrogen titanium phosphate. Products containing phosphates and/or proteins may adsorb either to the pellicle, rendering it more protective against demineralization, or directly to the dental hard tissue, probably competing with H(+) at specific sites on the tooth surface. Other substances may further enhance precipitation of calcium phosphates on the enamel surface, protecting it from additional acid impacts. Hence, the future of fluoride alone in erosion prevention looks grim, but the combination of fluoride with protective agents, such as polyvalent metal ions and some polymers, has much brighter prospects.

  2. Fluoridation Status of U. S. Army Conus Installations

    DTIC Science & Technology

    1993-09-30

    optimal levels of fluoridation in order to derive maximum effectiveness and to prevent the development of dental fluorosis . ൜. DISTRIBUTION...of fluoridation in order to derive maximum effectiveness and to prevent the development of dental fluorosis . iv Background Water fluoridation has been...dental fluorosis . Although this report only informs the commanders on fluoride concentrations for a specific date, it should constitute the first step

  3. FLUORIDE: A REVIEW OF USE AND EFFECTS ON HEALTH

    PubMed Central

    Kanduti, Domen; Sterbenk, Petra; Artnik, Barbara

    2016-01-01

    Introduction: Appropriate oral health care is fundamental for any individual’s health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. Aim: The aim of our research was to review the literature about fluoride toxicity and to inform physicians, dentists and public health specialists whether fluoride use is expedient and safe. Methods: Data we used in our review were systematically searched and collected from web pages and documents published from different international institutions. Results: Fluoride occurs naturally in our environment but we consume it in small amounts. Exposure can occur through dietary intake, respiration and fluoride supplements. The most important factor for fluoride presence in alimentation is fluoridated water. Methods, which led to greater fluoride exposure and lowered caries prevalence, are considered to be one of the greatest accomplishments in the 20th century`s public dental health. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Fluoride can be transmitted through the plasma into the mother’s milk; however, the concentration is low. The most important action of fluoride is topical, when it is present in the saliva in the appropriate concentration. The most important effect of fluoride on caries incidence is through its role in the process of remineralization and demineralization of tooth enamel. Acute toxicity can occur after ingesting one or more doses of fluoride over a short time period which then leads to poisoning. Today, poisoning is mainly due to unsupervised ingestion of products for dental and oral hygiene and over-fluoridated water. Conclusion: Even though fluoride can be toxic in extremely high concentrations, it`s topical use is safe. The European Academy of Paediatric Dentistry (EAPD) recommends a preventive topical use of fluoride supplements because of their

  4. METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

    DOEpatents

    Koshland, D.E. Jr.; Willard, J.E.

    1961-08-01

    A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

  5. Contamination of fluoride in groundwater and its effect on human health: a case study in hard rock aquifers of Siddipet, Telangana State, India

    NASA Astrophysics Data System (ADS)

    Narsimha, A.; Sudarshan, V.

    2016-06-01

    Hydrogeochemical investigation has been carried out in the granitic terrain of Siddipet area, Medak district, Telangana State, India with an aim to understand the distribution of fluoride in the groundwater and to understand the relationship of fluoride with other major ions, and also to identify the high fluoride-bearing groundwater zones. 104 groundwater samples were analyzed in the study area for fluoride and other major ions like calcium, magnesium, chloride, carbonate, bicarbonate, sodium, potassium, sulfate, and nitrate in addition to pH and electrical conductivity. The studies revealed that the concentration of fluoride in groundwater is ranging from 0.2 to 2.2 mg L-1 with a mean of 1.1 mg L-1. Nearly 22 % of groundwater has more than the permissible limit of fluoride (1.5 mg L-1), which is responsible for the endemic dental fluorosis in the area concerned. Geochemical classification of groundwater shows that Na-HCO3, Ca-Cl, and Ca-HCO3-Na are the dominant hydrochemical facies. Gibbs diagram shows rock-water interaction dominance and evaporation dominance, which are responsible for the change in the quality of water in the hard rock aquifer of the study area. The groundwater in villages and its environs are affected by fluoride contamination, and consequently majority of the population living in these villages suffer from dental fluorosis. Hence, they are advised to consume drinking water which has less than 1.5 mg L-1 fluoride to avoid further fluorosis risks.

  6. Geochemical provenance and spatial distribution of fluoride in groundwater of Mayo Tsanaga River Basin, Far North Region, Cameroon: implications for incidence of fluorosis and optimal consumption dose.

    PubMed

    Fantong, Wilson Y; Satake, Hiroshi; Ayonghe, Samuel N; Suh, Emmanuel C; Adelana, Segun M A; Fantong, Emilia Bi S; Banseka, Hycinth S; Gwanfogbe, Cletus D; Woincham, Leonard N; Uehara, Yoshitoshi; Zhang, Jing

    2010-04-01

    The 500,000 inhabitants of Mayo Tsanaga River Basin are vulnerable to a "silent" fluorosis from groundwater consumption. For the first time, the groundwater is investigated for the purpose of identifying the provenance of fluoride and estimating an optimal dose of fluoride in the study area. Based on the fluoride content of groundwater, fluorine and major oxides abundances in rocks from the study area, mean annual atmospheric temperature, and on-site diagnosis of fluorosis in children, the following results and conclusions are obtained: Fluoride concentration in groundwater ranges from 0.19 to 15.2 mg/l. Samples with fluoride content of <1.5 mg/l show Ca-HCO(3) signatures, while those with fluoride >1.5 mg/l show a tendency towards Na-HCO(3) type. Fluor-apatite and micas in the granites were identified as the main provenance of fluoride in the groundwater through water-rock interactions in an alkaline medium. The optimal fluoride dose in drinking water of the study area should be 0.7 mg/l, and could be adjusted downward to a level of 0.6 mg/l due to the high consumption rate of groundwater, especially during drier periods.

  7. The effect of supplementation of calcium, vitamin D, boron, and increased fluoride intake on bone mechanical properties and metabolic hormones in rat.

    PubMed

    Ghanizadeh, G; Babaei, M; Naghii, Mohammad Reza; Mofid, M; Torkaman, G; Hedayati, M

    2014-04-01

    Evidence indicates that optimal nutrition plays a role in bone formation and maintenance. Besides major components of mineralization such as calcium, phosphorus, and vitamin D, other nutrients like boron and fluoride have beneficial role, too. In this study, 34 male Wistar rats were divided into five groups: control diet, fluoride, fluoride + boron, fluoride + calcium + vitamin D, and fluoride + boron + calcium + vitamin D. Boron equal to 1.23 mg, calcium and vitamin D equal to 210 mg + 55 IU and fluoride equal to 0.7 mg/rat/day was added to their drinking water for 8 weeks. Plasma blood samples and bones were collected. Findings are evidence that fluoride + boron intake revealed significant positive effects on bone mechanical properties and bone metabolic hormones. These findings suggest that combined intake of these two elements has beneficial effects on bone stiffness and breaking strength comparing to even calcium + vitamin D supplementation. This evidence dealing with health problems related to bone and skeletal system in humans should justify further investigation of the role of boron and fluoride with other elements in relation to bone.

  8. Association between Urine Fluoride and Dental Fluorosis as a Toxicity Factor in a Rural Community in the State of San Luis Potosi

    PubMed Central

    Jarquín-Yañez, Lizet; Mejía-Saavedra, José de Jesús; Molina-Frechero, Nelly; Gaona, Enrique; Rocha-Amador, Diana Olivia; López-Guzmán, Olga Dania; Bologna-Molina, Ronell

    2015-01-01

    Objective. The aim of this study is to investigate urine fluoride concentration as a toxicity factor in a rural community in the state of San Luis Potosi, Mexico. Materials and Methods. A sample of 111 children exposed to high concentrations of fluoride in drinking water (4.13 mg/L) was evaluated. Fluoride exposure was determined by measuring urine fluoride concentration using the potentiometric method with an ion selective electrode. The diagnosis of dental fluorosis was performed by clinical examination, and the severity of damage was determined using Dean's index and the Thylstrup-Fejerskov (TF) index. Results. The range of exposure in the study population, evaluated through the fluoride content in urine, was 1.1 to 5.9 mg/L, with a mean of 3.14 ± 1.09 mg/L. Dental fluorosis was present in all subjects, of which 95% had severe cases. Higher urine fluoride levels and greater degrees of severity occurred in older children. Conclusions. The results show that dental fluorosis was determined by the presence of fluoride exposure finding a high positive correlation between the severity of fluorosis and urine fluoride concentration and the years of exposure suggested a cumulative effect. PMID:25789336

  9. Pharmacokinetics of fluoride in toddlers after application of 5% sodium fluoride dental varnish.

    PubMed

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

    2014-09-01

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

  10. Magnetic levitation of condensed hydrogen

    NASA Technical Reports Server (NTRS)

    Paine, C. G.; Seidel, G. M.

    1991-01-01

    Liquid and solid molecular hydrogen has been levitated using a pair of small superconducting solenoids. The hydrogen samples, up to 3 mm in dimension, were trapped in a magnetic potential having either a discrete minimum or a minimum in the form of a ring 1 cm in diameter. The hydrogen could be moved about in the magnetic trap by applying an electric field.

  11. Fluoride in drinking water and its removal.

    PubMed

    Meenakshi; Maheshwari, R C

    2006-09-01

    Excessive fluoride concentrations have been reported in groundwaters of more than 20 developed and developing countries including India where 19 states are facing acute fluorosis problems. Various technologies are being used to remove fluoride from water but still the problem has not been rooted out. In this paper, a broad overview of the available technologies for fluoride removal and advantages and limitations of each one have been presented based on literature survey and the experiments conducted in the laboratory with several processes. It has been concluded that the selection of treatment process should be site specific as per local needs and prevailing conditions as each technology has some limitations and no one process can serve the purpose in diverse conditions.

  12. Hydrogen production from microbial strains

    DOEpatents

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  13. A new perspective on metals and other contaminants in fluoridation chemicals*

    PubMed Central

    Mullenix, Phyllis J

    2014-01-01

    Background: Fluoride additives contain metal contaminants that must be diluted to meet drinking water regulations. However, each raw additive batch supplied to water facilities does not come labeled with concentrations per contaminant. This omission distorts exposure profiles and the risks associated with accidents and routine use. Objectives: This study provides an independent determination of the metal content of raw fluoride products. Methods: Metal concentrations were analyzed in three hydrofluorosilicic acid (HFS) and four sodium fluoride (NaF) samples using inductively coupled plasma-atomic emission spectrometry. Arsenic levels were confirmed using graphite furnace atomic absorption analysis. Results: Results show that metal content varies with batch, and all HFS samples contained arsenic (4.9–56.0 ppm) or arsenic in addition to lead (10.3 ppm). Two NaF samples contained barium (13.3–18.0 ppm) instead. All HFS (212–415 ppm) and NaF (3312–3630 ppm) additives contained a surprising amount of aluminum. Conclusions: Such contaminant content creates a regulatory blind spot that jeopardizes any safe use of fluoride additives. PMID:24999851

  14. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  15. 40 CFR 60.242 - Standard for fluorides.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for fluorides. 60.242 Section... Industry: Granular Triple Superphosphate Storage Facilities § 60.242 Standard for fluorides. (a) On and... atmosphere from any affected facility any gases which contain total fluorides in excess of 0.25...

  16. 40 CFR 60.232 - Standard for fluorides.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Standard for fluorides. 60.232 Section... Industry: Triple Superphosphate Plants § 60.232 Standard for fluorides. On and after the date on which the... gases which contain total fluorides in excess of 100 g/megagram (Mg) of equivalent P2O5 feed (0.20...

  17. 40 CFR 60.212 - Standard for fluorides.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Standard for fluorides. 60.212 Section... Industry: Superphosphoric Acid Plants § 60.212 Standard for fluorides. (a) On and after the date on which... facility any gases which contain total fluorides in excess of 5.0 g/megagram (Mg) of equivalent P2O5...

  18. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... as Components of Articles Intended for Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used as articles or components of articles intended for repeated...

  19. 40 CFR 60.232 - Standard for fluorides.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for fluorides. 60.232 Section... Industry: Triple Superphosphate Plants § 60.232 Standard for fluorides. On and after the date on which the... gases which contain total fluorides in excess of 100 g/megagram (Mg) of equivalent P2O5 feed (0.20...

  20. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... as Components of Articles Intended for Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used as articles or components of articles intended for repeated...