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Sample records for fluoride volatility process

  1. 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.

  2. Nitrogen Trifluoride-Based Fluoride- Volatility Separations Process: Initial Studies

    SciTech Connect

    McNamara, Bruce K.; Scheele, Randall D.; Casella, Andrew M.; Kozelisky, Anne E.

    2011-09-28

    This document describes the results of our investigations on the potential use of nitrogen trifluoride as the fluorinating and oxidizing agent in fluoride volatility-based used nuclear fuel reprocessing. The conceptual process uses differences in reaction temperatures between nitrogen trifluoride and fuel constituents that produce volatile fluorides to achieve separations and recover valuable constituents. We provide results from our thermodynamic evaluations, thermo-analytical experiments, kinetic models, and provide a preliminary process flowsheet. The evaluations found that nitrogen trifluoride can effectively produce volatile fluorides at different temperatures dependent on the fuel constituent.

  3. VOLATILE FLUORIDE PROCESS FOR SEPARATING PLUTONIUM FROM OTHER MATERIALS

    DOEpatents

    Spedding, F.H.; Newton, A.S.

    1959-04-14

    The separation of plutonium from uranium and/or tission products by formation of the higher fluorides of uranium and/or plutonium is discussed. Neutronirradiated uranium metal is first convcrted to the hydride. This hydrided product is then treatced with fluorine at about 315 deg C to form and volatilize UF/sup 6/ leaving plutonium behind. The plutonium may then be separated by reacting the residue with fluorine at about 500 deg C and collecting the volatile plutonium fluoride thus formed.

  4. Volatile fluoride process for separating plutonium from other materials

    DOEpatents

    Spedding, F. H.; Newton, A. S.

    1959-04-14

    The separation of plutonium from uranium and/or fission products by formation of the higher fluorides off uranium and/or plutonium is described. Neutronirradiated uranium metal is first converted to the hydride. This hydrided product is then treated with fluorine at about 315 deg C to form and volatilize UF/sub 6/ leaving plutonium behind. Thc plutonium may then be separated by reacting the residue with fluorine at about 5004DEC and collecting the volatile plutonium fluoride thus formed.

  5. Fluid-bed fluoride volatility process recovers uranium from spent uranium alloy fuels

    NASA Technical Reports Server (NTRS)

    Barghusen, J. J.; Chilenskas, A. A.; Gunderson, G. E.; Holmes, J. T.; Jonke, A. A.; Kincinas, J. E.; Levitz, N. M.; Potts, G. L.; Ramaswami, D.; Stethers, H.; Turner, K. S.

    1967-01-01

    Fluid-bed fluoride volatility process recovers uranium from uranium fuels containing either zirconium or aluminum. The uranium is recovered as uranium hexafluoride. The process requires few operations in simple, compact equipment, and eliminates aqueous radioactive wastes.

  6. FLUORIDE VOLATILITY PROCESS FOR THE RECOVERY OF URANIUM

    DOEpatents

    Katz, J.J.; Hyman, H.H.; Sheft, I.

    1958-04-15

    The separation and recovery of uraniunn from contaminants introduced by neutron irradiation by a halogenation and volatilization method are described. The irradiated uranium is dissolved in bromine trifluoride in the liquid phase. The uranium is converted to the BrF/sub 3/ soluble urmium hexafluoride compound whereas the fluorides of certain contaminating elements are insoluble in liquid BrF/sub 3/, and the reaction rate of the BrF/sub 3/ with certain other solid uranium contamirnnts is sufficiently slower than the reaction rate with uranium that substantial portions of these contaminating elements will remain as solids. These solids are then separated from the solution by a distillation, filtration, or centrifugation step. The uranium hexafluoride is then separated from the balance of the impurities and solvent by one or more distillations.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. PROCESS FOR THE PRODUCTION OF AMMONIUM URANIUM FLUORIDE

    DOEpatents

    Ellis, A.S.; Mooney, R.B.

    1953-08-25

    This patent relates to the preparation of ammonium uranium fluoride. The process comprises adding a water soluble fluoride to an aqueous solution of a uranous compound containing an ammonium salt, and isolating the resulting precipitate. This patent relates to the manufacture of uranium tetnafluoride from ammonium uranium fluoride, NH/sub 4/UF/sub 5/. Uranium tetrafluoride is prepared by heating the ammonium uranium fluoride to a temperature at which dissociation occurs with liberation of ammonium fluoride. Preferably the process is carried out under reduced pressure, or in a current of an inert gas.

  12. 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.

  13. Asporin and the mineralization process in fluoride-treated rats.

    PubMed

    Houari, Sophia; Wurtz, Tilmann; Ferbus, Didier; Chateau, Danielle; Dessombz, Arnaud; Berdal, Ariane; Babajko, Sylvie

    2014-06-01

    Microarray analysis of odontoblastic cells treated with sodium fluoride has identified the asporin gene as a fluoride target. Asporin is a member of the small leucine-rich repeat proteoglycan/protein (SLRP) family that is believed to be important in the mineralization process. In this study, asporin expression and distribution were investigated by systematic analysis of dentin and enamel, with and without fluoride treatment. Specific attention was focused on a major difference between the two mineralized tissues: the presence of a collagenous scaffold in dentin, and its absence in enamel. Normal and fluorotic, continually growing incisors from Wistar rats treated with 2.5 to 7.5 mM sodium fluoride (NaF) were studied by immunochemistry, in situ hybridization, Western blotting, and RT-qPCR. Asporin was continuously expressed in odontoblasts throughout dentin formation as expected. Asporin was also found, for the first time, in dental epithelial cells, particularly in maturation-stage ameloblasts. NaF decreased asporin expression in odontoblasts and enhanced it in ameloblasts, both in vivo and in vitro. The inverse response in the two cell types suggests that the effector, fluoride, is a trigger that elicits a cell-type-specific reaction. Confocal and ultrastructural immunohistochemistry evidenced an association between asporin and type 1 collagen in the pericellular nonmineralized compartments of both bone and dentin. In addition, transmission electron microscopy revealed asporin in the microenvironment of all cells observed. Thus, asporin is produced by collagen-matrix-forming and non-collagen-matrix-forming cells but may have different effects on the mineralization process. A model is proposed that predicts impaired mineral formation associated with the deficiency and excess of asporin.

  14. Effects of Gravity on Processing Heavy Metal Fluoride Fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Workman, Gary L.; Smith, Guy A.

    1997-01-01

    The effects of gravity on the crystal nucleation of heavy metal fluoride fibers have been studied in preliminary experiments utilizing NASA's KC-135 reduced gravity aircraft and a microgravity sounding rocket flight. Commercially produced fibers were heated to the crystallization temperature in normal and reduced gravity. The fibers processed in normal gravity showed complete crystallization while the fibers processed in reduced gravity did not show signs of crystallization.

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

    DOEpatents

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

    1961-05-01

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

  16. GADOLINIUM SOLUBILITY AND VOLATILITY DURING DWPF PROCESSING

    SciTech Connect

    Reboul, S

    2008-01-30

    Understanding of gadolinium behavior, as it relates to potential neutron poisoning applications at the DWPF, has increased over the past several years as process specific data have been generated. Of primary importance are phenomena related to gadolinium solubility and volatility, which introduce the potential for gadolinium to be separated from fissile materials during Chemical Process Cell (CPC) and Melter operations. Existing data indicate that gadolinium solubilities under moderately low pH conditions can vary over several orders of magnitude, depending on the quantities of other constituents that are present. With respect to sludge batching processes, the gadolinium solubility appears to be highly affected by iron. In cases where the mass ratio of Fe:Gd is 300 or more, the gadolinium solubility has been observed to be low, one milligram per liter or less. In contrast, when the ratio of Fe:Gd is 20 or less, the gadolinium solubility has been found to be relatively high, several thousands of milligrams per liter. For gadolinium to serve as an effective neutron poison in CPC operations, the solubility needs to be limited to approximately 100 mg/L. Unfortunately, the Fe:Gd ratio that corresponds to this solubility limit has not been identified. Existing data suggest gadolinium and plutonium are not volatile during melter operations. However, the data are subject to inherent uncertainties preventing definitive conclusions on this matter. In order to determine if gadolinium offers a practical means of poisoning waste in DWPF operations, generation of additional data is recommended. This includes: Gd solubility testing under conditions where the Fe:Gd ratio varies from 50 to 150; and Gd and Pu volatility studies tailored to quantifying high temperature partitioning. Additional tests focusing on crystal aging of Gd/Pu precipitates should be pursued if receipt of gadolinium-poisoned waste into the Tank Farm becomes routine.

  17. The mechanism for production of beryllium fluoride from the product of ammonium fluoride processing of beryllium- containing raw material

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The technique of fluorite-phenacite-bertrandite ores from Russian Ermakovskoe deposit processing by ammonium bifluoride is described. To determine the temperature mode and the thermal dissociation mechanism of ammonium tetrafluoroberyllate (the product of ammonium-fluoride leaching of the ore) the TG/DTA have been carried out. By IR spectroscopy and XRD the semi-products of ammonium tetrafluoroberyllate thermal dissociation have been identified. The hygroscopic low-temperature beryllium fluoride forms higher than 380°C. The less hydroscopic form of BeF2 have been produced at 600°C.

  18. [A fluoride-sensor for kink structure in DNA condensation process].

    PubMed

    Liu, Yan-Hui; Zhang, Jing; Chen, Ying-Bing; Li, Yu-Pu; Hu, Lin

    2014-01-01

    Bloomfield has pointed out that the kink structure occurs for sharp bending during DNA condensation process, until now, which has not been proved by experiments. Using UV Spectrophotometer, the effects of fluoride and chlorine on the polyamine-DNA condensation system can be detected. Fluoride and chlorine both belong to the halogen family, but their effects on spermine-DNA condensation system are totally different. Fluoride ions make blue-shift and hyperchromicity appear in the spermine-DNA condensation system, but chlorine ions only make insignificant hyperchromicity happen in this system. Both fluoride ions and chlorine ions only make insignificant hyperchromicity happen in spermidine-DNA condensation system. Based on the distinguished character of fluoride, a fluoride-sensor for "kink" structure in DNA condensation was developed and the second kind of "kink" structure only appear in the spermine-DNA condensation system.

  19. 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.

  20. A Process for Making Bulk Heavy Metal Fluoride Glasses.

    DTIC Science & Technology

    This invention relates to the preparation of glasses, and, in particular, relates to the preparation of heavy metal fluoride glasses with...reproducible high optical qualities. Considerable effort has been expended to develop heavy metal fluoride glasses ( HMFG ) as a viable family of infrared

  1. Volatility: A hidden Markov process in financial time series

    NASA Astrophysics Data System (ADS)

    Eisler, Zoltán; Perelló, Josep; Masoliver, Jaume

    2007-11-01

    Volatility characterizes the amplitude of price return fluctuations. It is a central magnitude in finance closely related to the risk of holding a certain asset. Despite its popularity on trading floors, volatility is unobservable and only the price is known. Diffusion theory has many common points with the research on volatility, the key of the analogy being that volatility is a time-dependent diffusion coefficient of the random walk for the price return. We present a formal procedure to extract volatility from price data by assuming that it is described by a hidden Markov process which together with the price forms a two-dimensional diffusion process. We derive a maximum-likelihood estimate of the volatility path valid for a wide class of two-dimensional diffusion processes. The choice of the exponential Ornstein-Uhlenbeck (expOU) stochastic volatility model performs remarkably well in inferring the hidden state of volatility. The formalism is applied to the Dow Jones index. The main results are that (i) the distribution of estimated volatility is lognormal, which is consistent with the expOU model, (ii) the estimated volatility is related to trading volume by a power law of the form σ∝V0.55 , and (iii) future returns are proportional to the current volatility, which suggests some degree of predictability for the size of future returns.

  2. Baldovin-Stella stochastic volatility process and Wiener process mixtures

    NASA Astrophysics Data System (ADS)

    Peirano, P. P.; Challet, D.

    2012-08-01

    Starting from inhomogeneous time scaling and linear decorrelation between successive price returns, Baldovin and Stella recently proposed a powerful and consistent way to build a model describing the time evolution of a financial index. We first make it fully explicit by using Student distributions instead of power law-truncated Lévy distributions and show that the analytic tractability of the model extends to the larger class of symmetric generalized hyperbolic distributions and provide a full computation of their multivariate characteristic functions; more generally, we show that the stochastic processes arising in this framework are representable as mixtures of Wiener processes. The basic Baldovin and Stella model, while mimicking well volatility relaxation phenomena such as the Omori law, fails to reproduce other stylized facts such as the leverage effect or some time reversal asymmetries. We discuss how to modify the dynamics of this process in order to reproduce real data more accurately.

  3. Volatile processes in Triton's atmosphere and surface

    NASA Technical Reports Server (NTRS)

    Lunine, J. I.

    1992-01-01

    A basic model for latitudinal transport of nitrogen is reviewed focusing on its limitations and some complications associated with surface and atmospheric physics. Data obtained by 1989 Voyager encounter with the Neptune system revealed the complexity in the pure nitrogen transport which is caused by the nonuniform albedo of the frosts. It is concluded that Triton is similar to Mars in terms of the complexity of volatile transport and to understand Triton's surface-atmosphere system, Mars may be a very good analog.

  4. PROCESS OF PREPARING A FLUORIDE OF TETRAVLENT URANIUM

    DOEpatents

    Wheelwright, E.J.

    1959-02-17

    A method is described for producing a fluoride salt pf tetravalent uranium suitable for bomb reduction to metallic uranium. An aqueous solution of uranyl nitrate is treated with acetic acid and a nitrite-suppressor and then contacted with metallic lead whereby uranium is reduced from the hexavalent to the tetravalent state and soluble lead acetate is formed. Sulfate ions are then added to the solution to precipitate and remove the lead values. Hydrofluoric acid and alkali metal ions are then added causing the formation of an alkali metal uranium double-fluoride in which the uranium is in the tetravalent state. After recovery, this precipitate is suitable for using in the limited production of metallic uranium.

  5. VOLATILE CHLORIDE PROCESS FOR THE RECOVERY OF METAL VALUES

    DOEpatents

    Hanley, W.R.

    1959-01-01

    A process is presented for recovering uranium, iron, and aluminum from centain shale type ores which contain uranium in minute quantities. The ore is heated wiih a chlorinating agent. such as chlorine, to form a volatilized stream of metal chlorides. The chloride stream is then passed through granular alumina which preferentially absorbs the volatile uranium chloride and from which the uranium may later be recovered. The remaining volatilized chlorides, chiefly those of iron and aluminum, are further treated to recover chlorine gas for recycle, and to recover ferric oxide and aluminum oxide as valuable by-products.

  6. 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.

  7. Theoretical studies of volatile processes in the outer solar system

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.

    1991-01-01

    Four studies of volatile processes in the outer solar system are discussed. Researchers suggest that the convective and conductive regions of Triton's atmosphere join at the tropopause near 10 km. A model of volatile transport on Triton's surface was constructed that predicts that Triton's surface north of 15 degrees north latitude is experiencing deposition of nitrogen frosts, as are the bright portions of the south polar cap near the equator. Also discussed are numerical models of the evolution of Titan's surface and atmosphere. Results of a study of the rheology of ammonia-water liquids were applied to the icy satellites of the outer solar system. Finally, the researchers examined the frictional heating, sublimation, and re-condensation of grains free-falling into the solar nebula from a surrounding interstellar cloud. The sublimation model includes the effect of various volatile species and accounts for the poor radiating properties of small grains using Mie theory.

  8. Active non-volatile memory post-processing

    DOEpatents

    Kannan, Sudarsun; Milojicic, Dejan S.; Talwar, Vanish

    2017-04-11

    A computing node includes an active Non-Volatile Random Access Memory (NVRAM) component which includes memory and a sub-processor component. The memory is to store data chunks received from a processor core, the data chunks comprising metadata indicating a type of post-processing to be performed on data within the data chunks. The sub-processor component is to perform post-processing of said data chunks based on said metadata.

  9. Highly packed and aligned fluoride substituted hydroxyapatite via a surfactant-free process.

    PubMed

    Xia, Wei; Lausmaa, Jukka; Thomsen, Peter; Engqvist, Håkan

    2012-01-01

    Biomolecules and surfactants are believed to be the key factors for reconstruction of tooth enamel and preparation of fluoride hydroxyapatite coating with enamel-like structure on dental implants. We have developed an alternative surfactant-free biomimetic method to stimulate growth of fluoride substituted hydroxyapatite coatings with highly packed and aligned structure on metallic substrates. Oxidized titanium plates were chosen as the substrates. The biomimetic fluoride hydroxyapatite was prepared by immersing the pretreated Ti plates into the phosphate-buffered solution with Ca(2+), H(2)PO(4)(-), HPO(4)(2-), and F(-). The pH value was controlled at 7.4 at the beginning. Every titanium plate (10 mm × 10 mm × 1 mm) was soaked into 20 mL of ion doped phosphate buffered solution in sealed plastic bottles, kept at 37°C or 60°C without stirring for time periods of 1 day to 2 weeks. After immersion, the samples were removed from the solution, rinsed with deionized water and allowed to dry in air. The fluoride substituted hydroxyapatite layer, composed of needle-like crystallites with the diameter of 10-20 nm, was well-organized and tightly packed. XRD results showed a sharper and stronger (002) peak, which could be used to explain that there was a preferable orientation along the c axis. The coating could be reconstructed on the former layer if the mineralization process was repeated, and the structure of the coating could be preserved. The method could be used to construct well organized fluoride substitute hydroxyapatite coating on metal implants.

  10. Integrated biological and physiochemical treatment process for nitrate and fluoride removal.

    PubMed

    Mekonen, A; Kumar, P; Kumar, A

    2001-09-01

    The feasibility of an integrated biological and physiochemical water treatment process for nitrate and fluoride removal has been evaluated. It consisted of two sequencing batch reactors (SBRs) in series. Performance of the process in the treatment of 24 synthetic water samples having nitrate concentrations of 40, 80, 120, 160, 200, and 250 mg/l (as N) and fluoride concentrations of 6, 10, 15, and 20 mg/l at different combinations was studied. Denitrification followed by defluoridation proved to be the best sequence of treatment. In all cases nitrate could be reduced to an acceptable level of less than 10 mg/l (as N) at 3, 5, and 7 h hydraulic retention times (HRTs) depending on its initial concentration. Fluoride concentrations up to 15 mg/l associated with nitrate concentrations up to 80 mg/l (as N) could be reduced acceptable 1.5 mg/l by alum-PAC slurry using alum doses up 850 mg/l [as Al2(SO4)3 x 16H2O] along with 100 mg/l of powdered activated carbon (PAC). Additional alkalinity produced during denitrification was used up during defluoridation for maintenance of pH avoiding the need for lime addition. On the other hand, residual organics, turbidity, and sulfide present in the denitrified water are removed by alum and PAC at the defluoridation stage along with fluoride, eliminating the need for an additional post-treatment step. At higher nitrate concentrations (> or = 120 mg/l as N), the alkalinity produced at the denitrification stage was in the range of 715-1175 mg/l as CaCO3. This excessive alkalinity inhibited reduction of fluoride to the level of 1.5 mg/l at the defluoridation stage, using alum doses up to 900 mg/l along with 100 mg/l of PAC. In all cases a fluoride concentration of 20 mg/l in water could not be reduced to the acceptable level of 1.5 mg/l.

  11. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    SciTech Connect

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-04-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  12. Lipid oxidation volatiles absent in milk after selected ultrasound processing.

    PubMed

    Juliano, Pablo; Torkamani, Amir Ehsan; Leong, Thomas; Kolb, Veronika; Watkins, Peter; Ajlouni, Said; Singh, Tanoj Kumar

    2014-11-01

    Ultrasonic processing can suit a number of potential applications in the dairy industry. However, the impact of ultrasound treatment on milk stability during storage has not been fully explored under wider ranges of frequencies, specific energies and temperature applications. The effect of ultrasonication on lipid oxidation was investigated in various types of milk. Four batches of raw milk (up to 2L) were sonicated at various frequencies (20, 400, 1000, 1600 and 2000kHz), using different temperatures (4, 20, 45 and 63°C), sonication times and ultrasound energy inputs up to 409kJ/kg. Pasteurized skim milk was also sonicated at low and high frequency for comparison. In selected experiments, non-sonicated and sonicated samples were stored at 4°C and were drawn periodically up to 14days for SPME-GCMS analysis. The cavitational yield, characterized in all systems in water, was highest between 400kHz and 1000kHz. Volatile compounds from milk lipid oxidation were detected and exceeded their odor threshold values at 400kHz and 1000kHz at specific energies greater than 271kJ/kg in raw milk. However, no oxidative volatile compounds were detected below 230kJ/kg in batch systems at the tested frequencies under refrigerated conditions. Skim milk showed a lower energy threshold for oxidative volatile formation. The same oxidative volatiles were detected after various passes of milk through a 0.3L flow cell enclosing a 20kHz horn and operating above 90kJ/kg. This study showed that lipid oxidation in milk can be controlled by decreasing the sonication time and the temperature in the system depending on the fat content in the sample among other factors.

  13. 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 ...

  14. 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 ...

  15. Emission characteristics of volatile compounds during sludges drying process.

    PubMed

    Deng, Wen-Yi; Yan, Jian-Hua; Li, Xiao-Dong; Wang, Fei; Zhu, Xiao-Wan; Lu, Sheng-Yong; Cen, Ke-Fa

    2009-02-15

    The emission characteristics of volatile compounds (VCs) during municipal sewage sludge (MSS) and paper mill sludge (PMS) drying process were investigated through experiments conducted on a lab-scale tubular drying furnace and a pilot-scale paddle dryer, respectively. The result indicated that five kinds of VCs, i.e. CO(2), NH(3), C(7)H(16) (n-heptane), volatile fatty acids (VFAs) and CH(4) were emitted during the drying process. It was found that the NH(3) and CO(2) were the primary compound released from the MSS drying process. In the case of the PMS, the VFAs and CO(2) were the main compounds released. The temperature and water content of sludge had great effects on the emission rates of NH(3), C(7)H(16), CO(2) and VFAs. The pH and chemical oxygen demand (COD) of condensate from the paddle dryer were also studied. It showed that pH and COD of condensate from MSS were much higher than that from the PMS, and that the higher COD value of the MSS condensate interrelated to the higher ammonium and sulfur content of it.

  16. Simultaneous arsenic and fluoride removal from synthetic and real groundwater by electrocoagulation process: Parametric and cost evaluation.

    PubMed

    Thakur, Lokendra Singh; Mondal, Prasenjit

    2017-04-01

    Co-existence of arsenic and fluoride in groundwater has raised severe health issues to living being. Thus, the present research has been conducted for simultaneous removal of arsenic and fluoride from synthetic groundwater by using electrocoagulation process with aluminum electrode. Effects of initial pH, current density, run time, inter electrode distance and NaCl concentration over percentage removal of arsenic and fluoride as well as operating cost have been studied. The optimum experimental conditions are found to be initial pH: 7, current density: 10 A/m(2), run time: 95 min, inter electrode distance: 1 cm, NaCl concentration: 0.71 g/l for removal of 98.51% arsenic (initial concentration: 550 μg/l) and 88.33% fluoride (initial concentration: 12 mg/l). The concentration of arsenic and fluoride in treated water are found to be 8.19 μg/l and 1.4 mg/l, respectively, with an operating cost of 0.357 USD/m(3) treated water. Pseudo first and second order kinetic model of individual and simultaneous arsenic and fluoride removal in electrocoagulation have also been studied. Produced sludge characterization studies also confirm the presence of arsenic in As(III) form, and fluoride in sludge. The present electrocoagulation process is able to reduce the arsenic and fluoride concentration of synthetic as well as real groundwater to below 10 μg/l and 1.5 mg/l, respectively, which are maximum contaminant level of these elements in drinking water according to WHO guidelines.

  17. Engineering subtilisin into a fluoride-triggered processing protease useful for one-step protein purification.

    PubMed

    Ruan, Biao; Fisher, Kathryn E; Alexander, Patrick A; Doroshko, Viktoriya; Bryan, Philip N

    2004-11-23

    Subtilisin was engineered into a highly specific, processing protease, and the subtilisin prodomain was coengineered into an optimized recognition sequence. This involved five steps. First, a robust subtilisin mutant was created, which could tolerate the subsequent mutations needed for high specificity. Second, the substrate binding pocket was mutated to increase its sequence selectivity. Third, the subtilisin prodomain was engineered to direct cleavage to the junction of any protein fused to it. Fourth, the active site of subtilisin was engineered to kinetically isolate binding and cleavage reactions. Finally, specific anions were identified to trigger the processing reaction, with fluoride ions being particularly useful. The ability to isolate the binding and processing steps with a triggering mechanism created a protease with a virtual on-off switch. This allowed column-immobilized processing subtilisin to be used as both the affinity ligand and processing protease for one-step purification of proteins. Fusion proteins tagged with the engineered prodomain can be bound to the column and washed free of contaminants. Cleavage can be triggered by the addition of fluoride to release the pure target protein. The column is then regenerated by stripping off the tightly bound prodomain at pH 2.1. Ten proteins have been purified to date by this method.

  18. System of extraction of volatiles from soil using microwave processes

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C. (Inventor); Kaukler, William F. (Inventor)

    2013-01-01

    A device for the extraction and collection of volatiles from soil or planetary regolith. The device utilizes core drilled holes to gain access to underlying volatiles below the surface. Microwave energy beamed into the holes penetrates through the soil or regolith to heat it, and thereby produces vapor by sublimation. The device confines and transports volatiles to a cold trap for collection.

  19. A Heck-Matsuda Process for the Synthesis of β-Arylethenesulfonyl Fluorides: Selectively Addressable Bis-electrophiles for SuFEx Click Chemistry.

    PubMed

    Qin, Hua-Li; Zheng, Qinheng; Bare, Grant A L; Wu, Peng; Sharpless, K Barry

    2016-11-02

    A Heck-Matsuda process for the synthesis of the otherwise difficult to access compounds, β-arylethenesulfonyl fluorides, is described. Ethenesulfonyl fluoride (i.e., vinylsulfonyl fluoride, or ESF) undergoes β-arylation with stable and readily prepared arenediazonium tetrafluoroborates in the presence of the catalyst palladium(II) acetate to afford the E-isomer sulfonyl analogues of cinnamoyl fluoride in 43-97 % yield. The β-arylethenesulfonyl fluorides are found to be selectively addressable bis-electrophiles for sulfur(VI) fluoride exchange (SuFEx) click chemistry, in which either the alkenyl moiety or the sulfonyl fluoride group can be the exclusive site of nucleophilic attack under defined conditions, making these rather simple cores attractive for covalent drug discovery.

  20. Evolution of polyvinylidene fluoride (PVDF) hierarchical morphology during slow gelation process and its superhydrophobicity.

    PubMed

    Li, Xianfeng; Zhou, Chong; Du, Runhong; Li, Nana; Han, Xutong; Zhang, Yufeng; An, Shulin; Xiao, Changfa

    2013-06-26

    In the paper, we proposed an evolution process of polyvinylidene fluoride (PVDF) macromolecular aggregation in a mixed solvent through the simple and slow gelation process at room temperature. The mixed solvent is prepared with a room-temperature solvent and a high-temperature solvent. The evolution process can be terminated by quenching and exchanging with nonsolvent in a nonsolvent coagulation bath properly, and then the vivid petal-like nanostructure and microspherulite is formed simultaneously. This hierarchical morphology endows PVDF with superhydrophobic and self-cleaning properties, which is useful to PVDF coating and membrane materials. The evolution processes are investigated through the measurements of differential scanning calorimetry (DSC), X-ray diffraction (XRD). In addition, the rheological properties of solution, dry gel and wet gel, are explored.

  1. Migration Processes and Volatiles Inventory to the Inner Planets

    NASA Technical Reports Server (NTRS)

    Marov, M. Y.; Ipatov, S. I.

    2004-01-01

    Comets and asteroids colliding with the terrestrial planets can deliver volatiles and organic or prebiotic compounds to the planets, thereby depositing on the planets the fundamental building-blocks for life. The inner planets contain heavier and cosmically less abundant elements in an iron-silicate matrix than the giant planets. This can be caused by the following three mechanisms: uneven fractionation and condensation in the accretionary disk; unequal degree of degassing of the composed matter; and heterogeneous accretion. Asteroid-size bodies consisting of the last low-temperature condensates (similar to most primitive chondritic meteorites, and enriched in hydrated silicates and trapped gases) are believed to have fallen onto the inner planets during the process of the giant planets formation. The relative contribution of either endogenous (i.e. outgassing) or exogenous (i.e. asteroid/comet collisions) sources is difficult to assess, although it is constrained by the pattern of noble gas abundances in the planetary atmospheres.

  2. DECONTAMINATION OF PLUTONIUM FOR FLUORIDE AND CHLORIDE DURING OXALATE PRECIPITATION, FILTRATION AND CALCINATION PROCESSES

    SciTech Connect

    Kyser, E.

    2012-07-25

    Due to analytical limitations for the determination of fluoride (F) and chloride (Cl) in a previous anion exchange study, an additional study of the decontamination of Pu from F and Cl by oxalate precipitation, filtration and calcination was performed. Anion product solution from the previous impurity study was precipitated as an oxalate, filtered, and calcined to produce an oxide for analysis by pyrohydrolysis for total Cl and F. Analysis of samples from this experiment achieved the purity specification for Cl and F for the proposed AFS-2 process. Decontamination factors (DF's) for the overall process (including anion exchange) achieved a DF of {approx}5000 for F and a DF of {approx}100 for Cl. Similar experiments where both HF and HCl were spiked into the anion product solution to a {approx}5000 {micro}g /g Pu concentration showed a DF of 5 for F and a DF of 35 for Cl across the combined precipitation-filtration-calcination process steps.

  3. TDDFT study on the sensing mechanism of a fluorescent sensor for fluoride anion: Inhibition of the ESPT process.

    PubMed

    Li, Guang-Yue; Liu, Dong; Zhang, Hang; Li, Wei-Wei; Wang, Feng; Liang, Ying-Hua

    2015-01-01

    The fluoride-sensing mechanism of a reported salicylaldehyde-based sensor (J. Photochem. Photobiol. B 2014, 138, 75) has been investigated by the TDDFT method. The present theoretical study indicates that there is an excited-state proton transfer (ESPT) process from the phenolic O-H moiety to the neighbor N atom in the sensor. The added fluoride anion could capture the proton in the O-H moiety and the corresponding phenolic anion is formed, which could inhibit the ESPT process. The experimental UV/Vis and fluorescence spectra are well reproduced by the calculated vertical excitation energies. Frontier molecular orbital analysis indicates that the local excited state of phenolic anion is responsible for its enhanced fluorescence. Due to this reason, the sensor can be used to sense fluoride anion by monitoring the fluorescent change.

  4. 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

  5. Luminescence and electrical properties of solution-processed ZnO thin films by adding fluorides and annealing atmosphere

    SciTech Connect

    Choi, Sungho; Park, Byung-Yoon; Jung, Ha-Kyun

    2011-06-15

    Highlights: {yields} Systematic study of the fluorides doped solution-processed ZnO thin films via the luminescence and electrical behaviors. {yields} Defect-related visible emission bands are affected by annealing ambient and fluoride addition. {yields} Adding lithium fluoride followed by annealing in oxygen ambient leads to a controlled defect density with proper TFT performance. -- Abstract: To develop an efficient channel layer for thin film transistors (TFTs), understanding the defect-related luminescence and electrical property is crucial for solution-processed ZnO thin films. Film growth with the fluorides addition, especially using LiF, followed by the oxygen ambient post-annealing leads to decreased defect-related emission as well as enhanced switching property. The saturation mobility and current on/off ratio are 0.31 cm{sup 2} V{sup -1} s{sup -1} and 1.04 x 10{sup 3}. Consequently, we can visualize an optimized process condition and characterization method for solution-processed TFT based on the fluorine-doped ZnO film channel layer by considering the overall emission behavior.

  6. Determination of volatiles produced during radiation processing in Laurus cinnamomum

    NASA Astrophysics Data System (ADS)

    Salum, D. C.; Araújo, M. M.; Fanaro, G. B.; Purgatto, E.; Villavicencio, A. L. C. H.

    2009-07-01

    In order to protect food from pathogenic microorganisms as well as increase its shelf-life, while keeping sensorial properties (e.g., odor and taste), which are important properties required by spice buyers, it is necessary to analyze volatile formation from irradiation of medicinal and food herbs. Possible changes in the odor of these herbs are evaluated by characterizing different radiation doses and effects on sensorial properties, in order to allow better application of the irradiation technology. The aim of the present study was to analyze volatile formation on cinnamon ( Laurus cinnamomum) samples after gamma irradiation. These samples were irradiated into plastic packages using a 60Co facility. Radiation doses applied were 0, 5, 10, 15, 20 and 25 kGy. For the analysis of the samples, solid-phase microextraction (SPME) was applied, while for the analysis of volatile compounds, CG/MS. Spice irradiation showed the highest decrease in volatile compounds. For L. cinnamomum, the irradiation decreased volatile compounds by nearly 56% and 89.5%, respectively, comparing to volatile from a sample which had not been previously irradiated.

  7. 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.

  8. 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.

  9. Lead enhances fluoride influence on apoptotic processes in the HepG2 liver cell line.

    PubMed

    Gutowska, Izabela; Baranowska-Bosiacka, Irena; Siwiec, Ewa; Szczuko, Małgorzata; Kolasa, Agnieszka; Kondarewicz, Anna; Rybicka, Marta; Dunaj-Stańczyk, Małgorzata; Wiernicki, Ireneusz; Chlubek, Dariusz; Stachowska, Ewa

    2016-03-01

    Chronic long-term exposure to high levels of fluoride leads to fluorosis, manifested by skeletal fluorosis and damage to internal organs, including kidneys, liver, parathyroid glands, and brain. Excess fluoride can also cause DNA damage, trigger apoptosis, and change cell cycle. The effect of fluoride may be exacerbated by lead (Pb), a potent inhibitor of many enzymes and a factor causing apoptosis, still present in the environment in excessive amounts. Therefore, in this study, we investigated the effects of sodium fluoride (NaF) and/or lead acetate (PbAc) on development of apoptosis, cell vitality, and proliferation in the liver cell line HepG2. We examined hepatocytes from the liver cell line HepG2, incubated for 48 h with NaF, PbAc, and their mixture (NaF + PbAc), and used for measuring apoptosis, index of proliferation, and vitality of cells. Incubation of the hepatocytes with NaF or PbAc increased apoptosis, more when fluoride and Pb were used simultaneously. Vitality of the cells depended on the compound used and its concentration. Proliferation slightly increased and then decreased in a high fluoride environment; it decreased significantly after addition of Pb in a dose-dependent manner. When used together, fluoride inhibited the decreasing effect of Pb on cell proliferation.

  10. 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.

  11. 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.

  12. 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.

  13. [Evaluation of the repair process in mechanically injured rat bone stimulated by sodium fluoride with non-toxic doses].

    PubMed

    Białecki, P

    1999-01-01

    The influence of sodium fluoride on the course of repair process in the mechanically injured rat bone was studied. Thirty six male Wistar rats aged 5 months, weighing 460-540 g were investigated. The animals lived under standard conditions and were fed ad libidum with the standard LSM food including 0.7 mg/kg of fluorine on the average. The animals randomly divided into 3 groups that comprised study and control groups, 6 rats each. The rats in the first group were given water with 20 mg (1.05 mmol) of sodium fluoride per kg of body weight for 24 h over a period of 2 weeks--group Ia. In the second group--IIa--animals were given water with sodium fluoride at a dose of 1.5 mmol/kg b.w./24 h for a period of 4 weeks. In the third group--IIIa--the animals were given sodium fluoride in a dose of 1.5 mmol/kg b.w./24 h for a period of 6 weeks. The rats from the control groups I, II and III were given water without sodium fluoride for the period of 2, 4 and 6 weeks, respectively. At the beginning of the experiment a hole was drilled in both femoral bones in rat under barbiturate anaesthesia. According to the protocol the rats underwent ether euthanasia after 2, 4 and 6 weeks after surgery and the following samples were collected: blood from the heart for biochemical studies and both femoral bones for biochemical and histological studies. The following parameters were evaluated in blood serum: fluorine, calcium, magnesium contents, serum concentrations of urea, creatinine, bilirubin and activity levels of enzymes: aspartate aminotransferase, alanine aminotransferase, cholinesterase, base phosphatase. Fluorine, calcium magnesium and zinc contents were estimated in bone samples. The concentration of fluorine ions in animal serum after 2, 4 and 6 weeks of experiment increased significantly as compared with the corresponding controls. The highest fluorine concentrations were observed in serum of rats supplemented with NaF for 6 weeks. The fluorine concentrations in the bone

  14. Effect of annealing process on the phase formation in poly(vinylidene fluoride) thin films

    SciTech Connect

    Abdullah, Ibtisam Yahya; Yahaya, Muhammad; Jumali, Mohd Hafizuddin Haji; Shanshool, Haider Mohammed

    2014-09-03

    This work reports the initial study on the effect of annealing process on the crystalline phase of poly(vinylidene fluoride) (PVDF) thin film. PVDF powder was dissolved in N,N-dimethylformamide before spin-coated onto a glass substrate to form a film. The films were annealed at 30°C, 90°C and 110°C for 5 hrs. The crystalline phase of the powder PVDF as received was investigated by using XRD and FTIR techniques. Moreover, the crystalline phases of thin films after annealing were investigated by using the same techniques. XRD analysis showed that in powder form PVDF exists in α-phase. Each annealed PVDF thin films exhibited identical formation of three-phases material namely γ (as major phase) while α and β phases as the minor phases. The FTIR analysis showed that the powder form of PVDF exists in α and β phases. FTIR measurement further confirmed the XRD results implying that the annealing process has no significant effect on the phase formation in PVDF films.

  15. Predicting biodegradable volatile solids degradation profiles in the composting process.

    PubMed

    Mason, I G

    2009-02-01

    This paper presents a new method for the prediction of the pattern of biodegradable volatile solids (BVS) degradation in the composting process. The procedure is based on a re-arrangement of the heat balance around a composting system to numerically solve for the rate of BVS carbon (BVS-C) disappearance. Input data for the model was obtained from composting experiments conducted in a laboratory-scale, constant temperature difference (CTD) reactor simulating a section of an aerated static pile, and using a simulated feedstock comprising ostrich feed, shredded paper, finished compost and woodchips. These experiments also provided validation data in the form of exit gas CO(2) carbon (CO(2)-C) profiles. The model successfully predicted the generic shape of experimental substrate degradation profiles obtained from CO(2) measurements, but under the conditions and assumptions of the experiment, the profiles were quantitatively different, giving an over-estimate of BVS-C. Both measured CO(2)-C and predicted BVS-C profiles were moderately to well fitted by a single exponential function, with replicated rate coefficient values of 0.08 and 0.09 d(-1), and 0.06 and 0.07 d(-1), respectively. In order to explore the underlying shape of the profiles, measured and predicted data at varying temperature were corrected to a constant temperature of 40 degrees C, using the temperature correction function of Rosso et al. [Rosso, L., Lobry, J.R., and Flandrois, J.P., 1993. An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model. Journal of Theoretical Biology, 162, 447-463], with cardinal temperatures of 5, 59 and 85 degrees C. Multi-phase profiles were generated for both the measured CO(2)-C and the predicted BVS-C data in this case. However, when alternative cardinal temperatures of 5, 55 and 80 degrees C, or 5, 50 and 80 degrees C, were used, the predicted profiles assumed an exponential shape, and excellent fits were obtained using a

  16. Rare-earth-doped bifunctional alkaline-earth metal fluoride nanocrystals via a facile microwave-assisted process.

    PubMed

    Pang, Min; Liu, Dapeng; Lei, Yongqian; Song, Shuyan; Feng, Jing; Fan, Weiqiang; Zhang, Hongjie

    2011-06-20

    Rare-earth-doped magnetic-optic bifunctional alkaline-earth metal fluoride nanocrystals have been successfully synthesized via a facile microwave-assisted process. The as-prepared nanocrystals were monodisperse and could form stable colloidal solutions in polar solvents, such as water and ethanol. They show bright-green fluorescence emisson. Furthermore, Gd(3+)-doped ones exhibit paramagnetic behavior at room temperature and superparamagnetic behavior at 2 K.

  17. The role of volatiles and lithology in the impact cratering process

    NASA Astrophysics Data System (ADS)

    Kieffer, S. W.; Simonds, C. H.

    1980-02-01

    A survey of published descriptions of 32 of the largest, least eroded terrestrial impact structures shows that the amount of melt at craters in crystalline rocks is approximately two orders of magnitude greater than that at craters in sedimentary rocks. A model is proposed for the impact process, and it is examined whether the difference in melt abundance is due to differences in the amount of melt generated in various target materials or due to differences in the fate of the melt during late stages of the impact. The model accounts semiquantitatively for the effects of porosity and water and volatile content on the cratering process. Important features of the model are noted. Even if the recondensation of released volatiles is very efficient, the cumulative effect of repeated impacts on accreting planets would be to continually transfer volatiles toward the outer surface. By this process, volatiles might be enriched toward the outer layer of a growing planet.

  18. Inorganic analyses of volatilized and condensed species within prototypic Defense Waste Processing Facility (DWPF) canistered waste

    SciTech Connect

    Jantzen, C.M.

    1992-06-30

    The high-level radioactive waste currently stored in carbon steel tanks at the Savannah River Site (SRS) will be immobilized in a borosilicate glass in the Defense Waste Processing Facility (DWPF). The canistered waste will be sent to a geologic repository for final disposal. The Waste Acceptance Preliminary Specifications (WAPS) require the identification of any inorganic phases that may be present in the canister that may lead to internal corrosion of the canister or that could potentially adversely affect normal canister handling. During vitrification, volatilization of mixed (Na, K, Cs)Cl, (Na, K, Cs){sub 2}SO{sub 4}, (Na, K, Cs)BF{sub 4}, (Na, K){sub 2}B{sub 4}O{sub 7} and (Na,K)CrO{sub 4} species from glass melt condensed in the melter off-gas and in the cyclone separator in the canister pour spout vacuum line. A full-scale DWPF prototypic canister filled during Campaign 10 of the SRS Scale Glass Melter was sectioned and examined. Mixed (NaK)CI, (NaK){sub 2}SO{sub 4}, (NaK) borates, and a (Na,K) fluoride phase (either NaF or Na{sub 2}BF{sub 4}) were identified on the interior canister walls, neck, and shoulder above the melt pour surface. Similar deposits were found on the glass melt surface and on glass fracture surfaces. Chromates were not found. Spinel crystals were found associated with the glass pour surface. Reference amounts of the halides and sulfates were found retained in the glass and the glass chemistry, including the distribution of the halides and sulfates, was homogeneous. In all cases where rust was observed, heavy metals (Zn, Ti, Sn) from the cutting blade/fluid were present indicating that the rust was a reaction product of the cutting fluid with glass and heat sensitized canister or with carbon-steel contamination on canister interior. Only minimal water vapor is present so that internal corrosion of the canister, will not occur.

  19. Climate, atmosphere, and volatile inventory evolution: Polar processes, climate records, volatile inventories

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1988-01-01

    Climate change on Mars was driven by long term changes in the solar luminosity, variations in the partitioning of volatiles between the atmosphere and near-surface reservoirs, and astronomical variations in axial and orbital properties. There are important parallels between these drives for Mars and comparable ones for Earth. In the early history of the solar system, the Sun's luminosity was 25 to 30 percent lower than its current value. It is suggested that an early benign climate on Earth was due to the presence of much more carbon dioxide in its atmosphere at these early times than currently resides there. Such a partitioning of carbon dioxide, at the expense of the carbonate rock reservoir, may have resulted from a more vigorous tectonic and volcanic style at early times. Such a line of reasoning may imply that much more carbon dioxide was present in the Martian atmosphere during the planet's early history than resides there today. It is now widely recognized that astronomical variations of the Earth's axial and orbital characteristics have played a dominant role in causing the succession of glacial and interglacial periods characterizing the last several million years. The magnitude of the axial and eccentricity variations are much larger for Mars than for Earth. Such changes on Mars could result in sizeable variations in atmospheric pressure, dust storm activity, and the stability of perennial carbon dioxide and water ice polar caps. These quasi-periodic climate changes occur on periods of 100,000 to 1,000,000 years and may be recorded in the sedimentary layers of the polar layered terrain.

  20. Relation between volatility correlations in financial markets and Omori processes occurring on all scales

    NASA Astrophysics Data System (ADS)

    Weber, Philipp; Wang, Fengzhong; Vodenska-Chitkushev, Irena; Havlin, Shlomo; Stanley, H. Eugene

    2007-07-01

    We analyze the memory in volatility by studying volatility return intervals, defined as the time between two consecutive fluctuations larger than a given threshold, in time periods following stock market crashes. Such an aftercrash period is characterized by the Omori law, which describes the decay in the rate of aftershocks of a given size with time t by a power law with exponent close to 1. A shock followed by such a power law decay in the rate is here called Omori process. We find self-similar features in the volatility. Specifically, within the aftercrash period there are smaller shocks that themselves constitute Omori processes on smaller scales, similar to the Omori process after the large crash. We call these smaller shocks subcrashes, which are followed by their own aftershocks. We also show that the Omori law holds not only after significant market crashes as shown by Lillo and Mantegna [Phys. Rev. E 68, 016119 (2003)], but also after “intermediate shocks.” By appropriate detrending we remove the influence of the crashes and subcrashes from the data, and find that this procedure significantly reduces the memory in the records. Moreover, when studying long-term correlated fractional Brownian motion and autoregressive fractionally integrated moving average artificial models for volatilities, we find Omori-type behavior after high volatilities. Thus, our results support the hypothesis that the memory in the volatility is related to the Omori processes present on different time scales.

  1. The etching process of boron nitride by alkali and alkaline earth fluorides under high pressure and high temperature

    SciTech Connect

    Guo, W.; Ma, H.A.; Jia, X.

    2014-03-01

    Graphical abstract: - Highlights: • Appropriate etch processes of hBN and cBN under HPHT are proposed. • The degree of the crystallization of hBN was decreased. • A special cBN growth mechanism with a triangular unit is proposed. • Plate-shape cBN crystals with large ratio of length to thickness were obtained. • A strategy provides useful guidance for controlling the cBN morphology. - Abstract: Some new etching processes of hexagonal boron nitride (hBN) and cubic boron nitride (cBN) under high pressure and high temperature in the presence of alkali and alkaline earth fluorides have been discussed. It is found that hBN is etched distinctly by alkali and alkaline earth fluorides and the morphology of hBN is significantly changed from plate-shape to spherical-shape. Based on the “graphitization index” values of hBN, the degree of the crystallization of hBN under high pressure and high temperature decreases in the sequence of LiF > CaF{sub 2} > MgF{sub 2}. This facilitates the formation of high-quality cBN single crystals. Different etch steps, pits, and islands are observed on cBN surface, showing the strong etching by alkali and alkaline earth fluorides and the tendency of layer-by-layer growth. A special layer growth mechanism of cBN with a triangular unit has been found. Furthermore, the morphologies of cBN crystals are apparently affected by a preferential surface etching of LiF, CaF{sub 2} and MgF{sub 2}. Respectively, the plate-shape and tetrahedral cBN crystals can be obtained in the presence of different alkali and alkaline earth fluorides.

  2. Does Enzymatic Hydrolysis of Glycosidically Bound Volatile Compounds Really Contribute to the Formation of Volatile Compounds During the Oolong Tea Manufacturing Process?

    PubMed

    Gui, Jiadong; Fu, Xiumin; Zhou, Ying; Katsuno, Tsuyoshi; Mei, Xin; Deng, Rufang; Xu, Xinlan; Zhang, Linyun; Dong, Fang; Watanabe, Naoharu; Yang, Ziyin

    2015-08-12

    It was generally thought that aroma of oolong tea resulted from hydrolysis of glycosidically bound volatiles (GBVs). In this study, most GBVs showed no reduction during the oolong tea manufacturing process. β-Glycosidases either at protein or gene level were not activated during the manufacturing process. Subcellular localization of β-primeverosidase provided evidence that β-primeverosidase was located in the leaf cell wall. The cell wall remained intact during the enzyme-active manufacturing process. After the leaf cell disruption, GBV content was reduced. These findings reveal that, during the enzyme-active process of oolong tea, nondisruption of the leaf cell walls resulted in impossibility of interaction of GBVs and β-glycosidases. Indole, jasmine lactone, and trans-nerolidol were characteristic volatiles produced from the manufacturing process. Interestingly, the contents of the three volatiles was reduced after the leaf cell disruption, suggesting that mechanical damage with the cell disruption, which is similar to black tea manufacturing, did not induce accumulation of the three volatiles. In addition, 11 volatiles with flavor dilution factor ≥4(4) were identified as relatively potent odorants in the oolong tea. These results suggest that enzymatic hydrolysis of GBVs was not involved in the formation of volatiles of oolong tea, and some characteristic volatiles with potent odorants were produced from the manufacturing process.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Microwave Processing of Planetary Surfaces for Volatile Extraction

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William

    2011-01-01

    In-Situ Resource Utilization will be necessary for sustained exploration of space. Volatiles are present in planetary soils, but water by far has the strongest potential for effective utilization. The presence of water at the lunar poles, Mars, and possibly on Phobos opens the possibility of producing LOX for propellant. Water is also a useful radiation shielding material and water (and oxygen) are expendables that are also required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating soil effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on soil dielectric properties. Methods for measuring the complex electric permittivity and magnetic permeability are being developed and have been measured for some lunar soil simulants at 0.5, 2.45, and 10 GHz from room temperature down to liquid nitrogen temperature. A new method for delivery of microwaves deep into a planetary surface is being prototyped with laboratory experiments and modeled with COMSOL MultiPhysics. We have plans to set up a planetary testbed in a large vacuum chamber in the coming year. Recent results will be presented.

  8. Microwave Processing of Planetary Surfaces for the Extraction of Volatiles

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William

    2011-01-01

    In-Situ Resource Utilization will be necessary for sustained exploration of space. Volatiles are present in planetary soils, but water by far has the most potential for effective utilization. The presence of water at the lunar poles, Mars, and possibly on Phobos opens the possibility of producing LOX for propellant. Water is also a useful radiation shielding material , and valuable to replenish expendables (water and oxygen) required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating soil effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on soil dielectric properties. Methods for complex electric permittivity and magnetic permeability measurement are being developed and used for measurements of lunar soil simulants. A new method for delivery of microwaves deep into a planetary surface is being prototyped with laboratory experiments and modeled with COMSOL MultiPhysics. We are planning to set up a planetary testbed in a large vacuum chamber in the coming year. Recent results are discussed.

  9. 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, ...

  10. Influence of thermal processing on the volatile constituents of muskmelon puree.

    PubMed

    Priyanka, D; Sindhoora, S; Vijayanand, P; Kulkarni, S G; Nagarajan, S

    2015-05-01

    Muskmelon (Cucumis melo L) is an important tropical fruit cultivated widely in different parts of India. Fresh muskmelon has a delicate but characteristic flavor rendering the fruit with highly acceptable flavor. Processing and preservation of muskmelon puree requires thermal processing, which affects the volatile constituents. It is imperative to understand the flavor changes during thermal processing which would affect the quality of the processed and packed muskmelon puree. Muskmelon puree was subjected to different methods of thermal processing viz., heating, canning and packing in retort pouches and the volatile constituents were analyzed. Gas chromatography-mass spectrometry (GC-MS) indicated the presence of more than 49 volatile components in the muskmelon puree samples. Major volatile components identified using GC-MS analysis showed the presence of esters (27.29 %), aldehydes (18.57 %), Heterocyclic compounds (16.63 %), aliphatic alcohols (11.72 %), phenolic compounds (6.03 %) and sesquiterpenes (0.25 %) in the fresh samples. Aldehydes decreased and ester content increased in thermally processed muskmelon puree packed in cans and retort pouches. Aliphatic alcohols, Heterocyclic compounds and phenolic compounds decreased in puree processed in tin containers and retort pouches.

  11. Spillage of lunar polar crater volatiles onto adjacent terrains: The case for dynamic processes

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; Hurley, D. M.; Zimmerman, M. I.

    2015-05-01

    We present an investigation of the release and transport of lunar polar crater volatiles onto topside regions surrounding the cold traps. The volatiles are liberated via surface energization processes associated with the harsh space environment, including solar wind plasma sputtering and impact vaporization. We find that some fraction of these volatiles can migrate from crater floors onto topside regions (those regions directly adjacent to and above the polar crater floors), and that these surrounding terrains should contain a sampling of the material originating within the crater itself. It is concluded that the nature of the volatile content on crater floors can be obtained by sampling the surface volatiles that have migrated or "spilled out" onto the adjacent terrain. This "spillage" effect could make human or robotic prospecting for crater resources significantly easier, since an assessment may not require direct entry into the very harsh polar crater environment. We also suggest that there are dynamic processes actively operating on the crater floors, and we estimate their source rates assuming dynamic equilibrium of the observed water frost and our modeled loss rates.

  12. Potential Signatures of Semi-volatile Compounds Associated With Nuclear Processing

    SciTech Connect

    Probasco, Kathleen M.; Birnbaum, Jerome C.; Maughan, A. D.

    2002-06-01

    Semi-volatile chemicals associated with nuclear processes (e.g., the reprocessing of uranium to produce plutonium for nuclear weapons, or the separation of actinides from processing waste streams), can provide sticky residues or signatures that will attach to piping, ducting, soil, water, or other surface media. Volatile compounds, that are more suitable for electro-optical sensing, have been well studied. However, the semi-volatile compounds have not been well documented or studied. A majority of these semi-volatile chemicals are more robust than typical gaseous or liquid chemicals and can have lifetimes of several weeks, months, or years in the environment. However, large data gaps exist concerning these potential signature compounds and more research is needed to fill these data gaps so that important signature information is not overlooked or discarded. This report investigates key semi-volatile compounds associated with nuclear separations, identifies available chemical and physical properties, and discusses the degradation products that would result from hydrolysis, radiolysis and oxidation reactions on these compounds.

  13. Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, S.; Walsh, M.; Svrluga, R.; Thomas, M.

    2015-11-01

    Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation's ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface

  14. Method for removing volatile components from a ceramic article, and related processes

    DOEpatents

    Klug, Frederic Joseph; DeCarr, Sylvia Marie

    2002-01-01

    A method of removing substantially all of the volatile component in a green, volatile-containing ceramic article is disclosed. The method comprises freezing the ceramic article; and then subjecting the frozen article to a vacuum for a sufficient time to freeze-dry the article. Frequently, the article is heated while being freeze-dried. Use of this method efficiently reduces the propensity for any warpage of the article. The article is often formed from a ceramic slurry in a gel-casting process. A method for fabricating a ceramic core used in investment casting is also described.

  15. Process model for ammonia volatilization from anaerobic swine lagoons incorporating varying wind speeds and biogas bubbling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ammonia volatilization from treatment lagoons varies widely with the total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model integrating ammonia ...

  16. Changes in flavor volatile composition of oolong tea after panning during tea processing.

    PubMed

    Sheibani, Ershad; Duncan, Susan E; Kuhn, David D; Dietrich, Andrea M; Newkirk, Jordan J; O'Keefe, Sean F

    2016-05-01

    Panning is a processing step used in manufacturing of some varieties of oolong tea. There is limited information available on effects of panning on oolong tea flavors. The goal of this study was to determine effects of panning on flavor volatile compositions of oolong using Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O). SDE and SPME techniques were applied for extraction of volatiles in panned and unpanned teas. A total of 190 volatiles were identified from SDE and SPME extractions using GC-MS and GC-O. There were no significant differences (P > 0.05) in aldehyde or terpene contents of unpanned and panned tea. However, alcohols, ketones, acids and esters contents were significantly reduced by panning. Among 12 major volatiles previously used for identification and quality assessment of oolong tea, trans nerolidol, 2- hexenal, benzaldehyde, indole, gernaiol, and benzenacetaldehyde contents were significantly decreased (P < 0.05) by panning. Panning increased (P < 0.05) contents of linalool oxide, cis jasmone, and methyl salicylate. The GC-O study also showed an increase of aroma active compounds with sweet descriptions and decrease of aroma active compounds with fruity and smoky descriptions after panning. Panning significantly changes the volatile compositions of the tea and created new aroma active compounds. Results from this study can be used in quality assessment of panned oolong tea.

  17. 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.

  18. Design and development of sustainable remediation process for mitigation of fluoride contamination in ground water and field application for domestic use.

    PubMed

    Gwala, Poonam; Andey, Subhash; Nagarnaik, Pranav; Ghosh, Sarika Pimpalkar; Pal, Prashant; Deshmukh, Prashant; Labhasetwar, Pawan

    2014-08-01

    Decentralised household chemo defluoridation unit (CDU) was developed and designed based on a combination of coagulation and sorption processes. Chemo-defluoridation process was optimised to reduce use of chemicals and increase acceptability among beneficiaries without affecting palatability of water. Chemical dose optimization undertaken in the laboratory using jar test revealed the optimum calcium salt to initial fluoride ratio of 60 for fluoride removal. Performance of CDU was evaluated in the laboratory for removal efficiency, water quality parameters, filter bed cleaning cycle and desorption of fluoride. CDU evaluation in the laboratory with spiked water (5 mg/L) and field water (~4.2 mg/L) revealed treated water fluoride concentration of less than 1mg/L. Seventy five CDUs were installed in households at Sakhara Village, Yavatmal District in Maharashtra State of India. Monthly monitoring of CDUs for one year indicated reduction of the raw water fluoride concentration from around 4 mg/L to less than 1mg/L. Post implementation survey after regular consumption of treated drinking water by the users for one year indicated user satisfaction and technological sustainability.

  19. 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).

  20. Virtual volatility

    NASA Astrophysics Data System (ADS)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation strategy.

  1. Lipid oxidation in baked products: impact of formula and process on the generation of volatile compounds.

    PubMed

    Maire, Murielle; Rega, Barbara; Cuvelier, Marie-Elisabeth; Soto, Paola; Giampaoli, Pierre

    2013-12-15

    This paper investigates the effect of ingredients on the reactions occurring during the making of sponge cake and leading to the generation of volatile compounds related to flavour quality. To obtain systems sensitive to lipid oxidation (LO), a formulation design was applied varying the composition of fatty matter and eggs. Oxidation of polyunsaturated fatty acids (PUFA) and formation of related volatile compounds were followed at the different steps of cake-making. Optimised dynamic Solid Phase Micro Extraction was applied to selectively extract either volatile or semi-volatile compounds directly from the baking vapours. We show for the first time that in the case of alveolar baked products, lipid oxidation occurs very early during the step of dough preparation and to a minor extent during the baking process. The generation of lipid oxidation compounds depends on PUFA content and on the presence of endogenous antioxidants in the raw matter. Egg yolk seemed to play a double role on reactivity: protecting unsaturated lipids from oxidation and being necessary to generate a broad class of compounds of the Maillard reaction during baking and linked to the typical flavour of sponge cake.

  2. Shrinkage void formation and its effect on freeze and thaw processes of lithium and lithium-fluoride for space applications

    NASA Technical Reports Server (NTRS)

    Yang, Jae Y.; El-Genk, Mohamed S.

    1991-01-01

    The effects of shrinkage void forming during freezing of lithium and lithium fluoride on subsequent thaw processes are investigated using a numerical scheme that is based on a single (solid/liquid) cell approach. Results show that a void forming at the wall appreciably reduces the solid-liquid interface velocity, during both freeze and thaw, and causes a substantial rise in the wall temperature during thaw. However, in the case of Li, the maximum wall temperature was much lower than the melting temperature of PWC-11, which is used as the structure material in the SP-100 system. Hence, it is concluded that a formation of hot spots is unlikely during the startup or restart of the SP-100 system.

  3. Automated signal processing applied to volatile-based inspection of greenhouse crops.

    PubMed

    Jansen, Roel; Hofstee, Jan Willem; Bouwmeester, Harro; van Henten, Eldert

    2010-01-01

    Gas chromatograph-mass spectrometers (GC-MS) have been used and shown utility for volatile-based inspection of greenhouse crops. However, a widely recognized difficulty associated with GC-MS application is the large and complex data generated by this instrument. As a consequence, experienced analysts are often required to process this data in order to determine the concentrations of the volatile organic compounds (VOCs) of interest. Manual processing is time-consuming, labour intensive and may be subject to errors due to fatigue. The objective of this study was to assess whether or not GC-MS data can also be automatically processed in order to determine the concentrations of crop health associated VOCs in a greenhouse. An experimental dataset that consisted of twelve data files was processed both manually and automatically to address this question. Manual processing was based on simple peak integration while the automatic processing relied on the algorithms implemented in the MetAlign™ software package. The results of automatic processing of the experimental dataset resulted in concentrations similar to that after manual processing. These results demonstrate that GC-MS data can be automatically processed in order to accurately determine the concentrations of crop health associated VOCs in a greenhouse. When processing GC-MS data automatically, noise reduction, alignment, baseline correction and normalisation are required.

  4. METAL RECOVERY PROCESS

    DOEpatents

    Werner, L.B.; Hill, O.F.

    1957-12-01

    A process is presented for the separation of plutonium from the niobium oxide which is frequently used as a carrier precipitate to separate the plutonium from solutions of dissolved fuel elements. The niobium oxide, plutonium bearing precipitate is treated with hydrogen fluoride converting the niobium to the volatile pentafluoride, while the plutonium is changed into the substantially non- volatile plutonium tetrafluoride. After the niobium has been removed, the plutonium tetrafluoride is reacted with elemental fluorine, converting it to a higher plutonium fluoride and this may in turn be volitilized away from any residual impurities.

  5. The role of volatiles and lithology in the impact cratering process.

    USGS Publications Warehouse

    Werner, Kieffer S.; Simonds, C.H.

    1980-01-01

    A survey of published descriptions of 32 of the largest, least eroded terrestrial impact structures reveals that the amount of melt at craters in crystalline rocks is approximately 2 orders of magnitude greater than at craters in sedimentary rocks. In this paper we present a model for the impact process; calculations show that the volume of material shocked to pressures sufficient for melting should not be significantly different in sedimentary and crystalline rocks. We conclude that shock melt is formed in the early stages of the cratering process by impacts into rocks rich in volatiles but is destroyed by the cratering process. -from Authors

  6. Resource Prospector Instrumentation for Lunar Volatiles Prospecting, Sample Acquisition and Processing

    NASA Technical Reports Server (NTRS)

    Captain, J.; Elphic, R.; Colaprete, A.; Zacny, Kris; Paz, A.

    2016-01-01

    Data gathered from lunar missions within the last two decades have significantly enhanced our understanding of the volatile resources available on the lunar surface, specifically focusing on the polar regions. Several orbiting missions such as Clementine and Lunar Prospector have suggested the presence of volatile ices and enhanced hydrogen concentrations in the permanently shadowed regions of the moon. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was the first to provide direct measurement of water ice in a permanently shadowed region. These missions with other orbiting assets have laid the groundwork for the next step in the exploration of the lunar surface; providing ground truth data of the volatiles by mapping the distribution and processing lunar regolith for resource extraction. This next step is the robotic mission Resource Prospector (RP). Resource Prospector is a lunar mission to investigate 'strategic knowledge gaps' (SKGs) for in-situ resource utilization (ISRU). The mission is proposed to land in the lunar south pole near a permanently shadowed crater. The landing site will be determined by the science team with input from broader international community as being near traversable landscape that has a high potential of containing elevated concentrations of volatiles such as water while maximizing mission duration. A rover will host the Regolith & Environment Science and Oxygen & Lunar Volatile Extraction (RESOLVE) payload for resource mapping and processing. The science instruments on the payload include a 1-meter drill, neutron spectrometer, a near infrared spectrometer, an operations camera, and a reactor with a gas chromatograph-mass spectrometer for volatile analysis. After the RP lander safely delivers the rover to the lunar surface, the science team will guide the rover team on the first traverse plan. The neutron spectrometer (NS) and near infrared (NIR) spectrometer instruments will be used as prospecting tools to guide

  7. Impact of Anaerobic Digestion of Liquid Dairy Manure on Ammonia Volatilization Process

    NASA Astrophysics Data System (ADS)

    Koirala, K.

    2013-12-01

    The goal of this study was to determine the effect of anaerobic digestion (AD) on the mechanism of ammonia volatilization from liquid dairy manure, in storage or treatment lagoon, prior to land application. Physical-chemical properties of liquid dairy manure, which may affect ammonia volatilization process, were determined before and after AD. The properties of interest included: particle size distribution (PSD), total solids (TS), volatile solids (VS), viscosity, pH, total ammoniacal nitrogen (TAN), and ionic strength (IS). The overall mass transfer coefficient of ammonia (KoL) and the NH3 fraction of TAN (β) for the undigested (UD) and AD manures were then experimentally determined in a laboratory convective emission chamber (CEC) at a constant wind speed of 1.5 m s-1 and fixed air temperature of 25 °C at liquid manure temperatures of 15, 25, and 35 °C. The PSD indicated non-normal left skewed distribution for both AD and UD manures particles, suggestive of heavier concentrations of particles towards the lower particle size range. The volume median diameters (VMD) for solids from UD and AD were not significantly different (p= 0.65), but the geometric standard deviations (GSD) were significantly different (p = 0.001), indicating slightly larger particles but more widely distributed solids in UD than AD manure. Results also indicated significantly higher pH, TAN, ionic strength (IS) and viscosity in AD manure. The KoL and β for AD manure determined under identical conditions (air temperature, liquid temperature, and airflow) were significantly higher (p > 0.05) than for UD manure. Overall, these findings suggest that AD of dairy manure significantly increased initial ammonia volatilization potential from liquid dairy manure; with the largest increase (~62%) emanating from increased ammonium dissociation. The initial flux of ammonia, during the experiment period, was ~84% more from AD than in UD dairy manure. Keywords. Process based models, mass transfer

  8. 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

  9. Removal of fluoride from drinking water using modified ultrafine tea powder processed using a ball-mill

    NASA Astrophysics Data System (ADS)

    Cai, Huimei; Xu, Lingyun; Chen, Guijie; Peng, Chuanyi; Ke, Fei; Liu, Zhengquan; Li, Daxiang; Zhang, Zhengzhu; Wan, Xiaochun

    2016-07-01

    A low-cost and highly efficient biosorbent was prepared by loading zirconium(IV) onto ball-milled, ultrafine tea powder (UTP-Zr) for removal of fluoride from drinking water. To evaluate the fluoride adsorption capacity of UTP-Zr over a wide range of conditions, the biosorbent dosage, contact time, initial pH, initial fluoride concentration and presence of other ions were varied. UTP-Zr performed well over the considerably wide pH range of 3-10. The residual concentration of Zr in the treated water was below the limit of detection (0.01 mg/L). Fluoride adsorption by the UTP-Zr biosorbent followed the Langmuir model, with a maximum adsorption capacity of 12.43 mgF/g at room temperature. The fluoride adsorption kinetics fit the pseudo-second-order kinetic model. The synthesized biosorbent was characterized by BET, SEM, EDS, XRD and XPS to reveal how UTP-Zr interacts with fluoride. Results from this study demonstrated that UTP-based biosorbents will be useful and safe for the removal of fluoride from drinking water.

  10. Understanding the determinants of volatility clustering in terms of stationary Markovian processes

    NASA Astrophysics Data System (ADS)

    Miccichè, S.

    2016-11-01

    Volatility is a key variable in the modeling of financial markets. The most striking feature of volatility is that it is a long-range correlated stochastic variable, i.e. its autocorrelation function decays like a power-law τ-β for large time lags. In the present work we investigate the determinants of such feature, starting from the empirical observation that the exponent β of a certain stock's volatility is a linear function of the average correlation of such stock's volatility with all other volatilities. We propose a simple approach consisting in diagonalizing the cross-correlation matrix of volatilities and investigating whether or not the diagonalized volatilities still keep some of the original volatility stylized facts. As a result, the diagonalized volatilities result to share with the original volatilities either the power-law decay of the probability density function and the power-law decay of the autocorrelation function. This would indicate that volatility clustering is already present in the diagonalized un-correlated volatilities. We therefore present a parsimonious univariate model based on a non-linear Langevin equation that well reproduces these two stylized facts of volatility. The model helps us in understanding that the main source of volatility clustering, once volatilities have been diagonalized, is that the economic forces driving volatility can be modeled in terms of a Smoluchowski potential with logarithmic tails.

  11. Volatile, anthocyanidin, quality and sensory changes in rabbiteye blueberry from whole fruit through pilot plant juice processing.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: High antioxidant content and keen marketing have increased blueberry demand and increased local production which in turn mandates new uses for abundant harvests. Pilot scale processes were employed to investigate the anthocyanidin profiles, qualitative volatile compositions, and sensori...

  12. 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.

  13. To melt is not enough: Retention of volatile species through internal processing in icy bodies

    NASA Astrophysics Data System (ADS)

    Sarid, G.; Stewart-Mukhopadhyay, S.

    2014-07-01

    The outer Solar System hosts a vast population of small icy bodies, considered to be primitive remnants from the planet-formation epoch. Early thermal and collisional processes affected such planetesimals to varying degrees depending on the time scale and dynamics of early planet growth. Recent observations have revealed that many large (>˜1000 km in diameter) transneptunian objects (TNOs) exhibit features of crystalline water ice in their surface spectra [1], as well as spectral features of more volatile ices, such as methane or hydrated ammonia [2]. These telltale observations should be accounted for when considering the alteration history and bulk processing of dwarf planets and their icy progeny. We will discuss preliminary calculations of early evolution scenarios for small icy-rocky bodies formed beyond the water-ice snow line. Such objects should also contain non-negligible fractions of pre-organic volatile compounds. The volatile composition and interior structure of these objects may change considerably due to internal heating and/or collisional modification prior to settling in their current (relatively quiescent) dynamical niches. Our initial model for the objects in question is that of a porous aggregate of various volatile compounds (as ices or trapped gases) and refractory silicate-metal solid grains, comprising the bulk matrix [3]. Chemical compositions for these objects are taken from existing simulations of chemical and dynamical evolution of disk material [4]. The key volatile species (e.g., H_2O, CO, CO_2, NH_3, CH_4, and CH_3OH) are also the most commonly observed in comets [5], which are remnants of such an early planetesimal population. Thermal and chemical internal evolution is examined self-consistently, as the abundances and locations of all species evolve, and we record mass ratios, temperatures, pressures, and porosity variations. The presence of volatile species in the interior can affect the overall heat balance and accompanied phase

  14. Purex Processing of Dissolved Sand, Slag, and Crucible Containing High Levels of Boric Acid and Calcium Fluoride

    SciTech Connect

    Kyser, E.A.

    1998-05-01

    The plutonium solution obtained from the dissolution of SSC in F- Canyon will be high in fluoride. Flowsheet adjustments must be made to increase the plutonium extraction in the solvent extraction cycle to keep Pu losses from being excessive.

  15. 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

  16. 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

  17. Effect of suspended particles upon drying process of volatile droplet sitting on solid surface

    NASA Astrophysics Data System (ADS)

    Ueno, I.; Kochiya, K.

    Particle motion in volatile droplet on the solid surface especially the behavior of particles depositing in the vicinity of solid-liquid-gas boundary line contact line is focused This phenomenon is called as coffee stain problem Particle motion in the droplet is analyzed by reconstruction of spatio-temporal particle motion by applying three-dimensional particle tracking velocimetry 3-D PTV We discuss the effect of the suspended particles upon the drying process of the droplet Morphological discussion on the particles stuck on the solid surface after the dryout the droplet is also conducted

  18. Environmental guideline for the reduction of volatile organic compound emissions from the plastics processing industry

    SciTech Connect

    1997-12-31

    The purpose of this document is to provide guidance to environmental regulatory agencies, manufacturers, and operators of plastics processing plants regarding the means of reducing emissions containing volatile organic compounds (VOCs) which are released to the environment in the course of production. Sectors covered by the guideline are expanded polystyrene, cellular polyethylene foams, polyvinyl chloride, and reinforced plastics and composites made from thermoset polyester resins. The guideline focuses on the reduction of VOC emissions from processing and clean-up operations, the handling and storage of VOC-containing materials, and the handling and disposal of wastes. The guideline contains material, equipment, process, and operating standards for plastics processing facilities, record keeping and training standards, recommended operating practices, and testing protocols.

  19. On the connection between financial processes with stochastic volatility and nonextensive statistical mechanics

    NASA Astrophysics Data System (ADS)

    Queirós, S. M. D.; Tsallis, C.

    2005-11-01

    The GARCH algorithm is the most renowned generalisation of Engle's original proposal for modelising returns, the ARCH process. Both cases are characterised by presenting a time dependent and correlated variance or volatility. Besides a memory parameter, b, (present in ARCH) and an independent and identically distributed noise, ω, GARCH involves another parameter, c, such that, for c=0, the standard ARCH process is reproduced. In this manuscript we use a generalised noise following a distribution characterised by an index qn, such that qn=1 recovers the Gaussian distribution. Matching low statistical moments of GARCH distribution for returns with a q-Gaussian distribution obtained through maximising the entropy Sq=1-sumipiq/q-1, basis of nonextensive statistical mechanics, we obtain a sole analytical connection between q and left( b,c,qnright) which turns out to be remarkably good when compared with computational simulations. With this result we also derive an analytical approximation for the stationary distribution for the (squared) volatility. Using a generalised Kullback-Leibler relative entropy form based on Sq, we also analyse the degree of dependence between successive returns, zt and zt+1, of GARCH(1,1) processes. This degree of dependence is quantified by an entropic index, qop. Our analysis points the existence of a unique relation between the three entropic indexes qop, q and qn of the problem, independent of the value of (b,c).

  20. {sup 252}Cf-source-correlated transmission measurements for uranyl fluoride deposit in a 24-in.-OD process pipe

    SciTech Connect

    Uckan, T.; Mihalczo, J.T.; Valentine, T.E.; Mullens, J.A.; Wyatt, M.S.; Hannon, T.F.

    1998-06-01

    Characterization of a hydrated uranyl fluoride (UO{sub 2}F{sub 2}{center_dot}nH{sub 2}O) deposit in a 17-ft-long, 24-in.-OD process pipe at the former Oak Ridge Gaseous Diffusion Plant was successfully performed by using {sup 252}Cf-source-correlated time-of-flight (TOF) transmission measurements. These measurements of neutrons and gamma rays through the pipe from an external {sup 2521}Cf fission source were used to measure the deposit profile and its distribution along the pipe, the hydration (or H/U), and the total uranium mass. The measurements were performed with a source in an ionization chamber on one side of the pipe and detectors on the other. Scanning the pipe vertically and horizontally produced a spatial and time-dependent radiograph of the deposit in which transmitted gamma rays and neutrons were separated in time. The cross-correlation function between the source and the detector was measured with the Nuclear Weapons Identification System. After correcting for pipe effects, the deposit thickness was determined from the transmitted neutrons and H/U from the gamma rays. Results were consistent with a later intrusive observation of the shape and the color of the deposit; i.e., the deposit was annular and was on the top of the pipe at some locations, demonstrating the usefulness of this method for deposit characterization.

  1. An investigation of voids formation mechanisms and their effects on freeze and thaw processes of lithium and lithium fluoride

    NASA Technical Reports Server (NTRS)

    El-Genk, Mohamed S.; Yang, Jae-Young

    1991-01-01

    The mechanisms of void formation during the cooldown and freezing of lithium coolant within the primary loop of SP-100 type systems are investigated. These mechanisms are: (1) homogeneous nucleation; (2) heterogeneous nucleation; (3) normal segregation of helium gas dissolved in liquid lithium; and (4) shrinkage of lithium during freezing. To evaluate the void formation potential due to segregation, a numerical scheme that couples the freezing and mass diffusion processes in both the solid and liquid regions is developed. The results indicated that the formation of He bubbles is unlikely by either homogeneous or heterogeneous nucleation during the cooldown process. However, homogeneous nucleation of He bubbles following the segregation of dissolved He in liquid lithium ahead of the solid-liquid interface is likely to occur. Results also show that total volume of He void is insignificant when compared to that of shrinkage voids. In viewing this, the subsequent research focuses on the effects of shrinkage void forming during freezing of lithium on subsequent thaw processes are investigated using a numerical scheme that is based on a single (solid/liquid) cell approach. The cases of lithium-fluoride are also investigated to show the effect of larger volume shrinkage upon freezing on the freeze and thaw processes. Results show that a void forming at the wall appreciably reduces the solid-liquid interface velocity, during both freeze and thaw, and causes a substantial rise in the wall temperature during thaw. However, in the case of Li, the maximum wall temperature was much lower than the melting temperature of PWC-11, which is used as the structure material in the SP-100 system. Hence, it is included that a formation of hot spots is unlikely during the startup or restart of the SP-100 system.

  2. Optimization of process parameters for production of volatile fatty acid, biohydrogen and methane from anaerobic digestion.

    PubMed

    Khan, M A; Ngo, H H; Guo, W S; Liu, Y; Nghiem, L D; Hai, F I; Deng, L J; Wang, J; Wu, Y

    2016-11-01

    The anaerobic digestion process has been primarily utilized for methane containing biogas production over the past few years. However, the digestion process could also be optimized for producing volatile fatty acids (VFAs) and biohydrogen. This is the first review article that combines the optimization approaches for all three possible products from the anaerobic digestion. In this review study, the types and configurations of the bioreactor are discussed for each type of product. This is followed by a review on optimization of common process parameters (e.g. temperature, pH, retention time and organic loading rate) separately for the production of VFA, biohydrogen and methane. This review also includes additional parameters, treatment methods or special additives that wield a significant and positive effect on production rate and these products' yield.

  3. Influence of processing on the volatile profile of strawberry spreads made with isomaltulose.

    PubMed

    Peinado, I; Rosa, E; Heredia, A; Escriche, I; Andrés, A

    2013-05-01

    A new strawberry spread formulated with fructose and isomaltulose (replacing sucrose partially or totally) and a high percentage of fruit was developed in line with the new trend of healthier products. This work studies the influence of some process variables (percentage of sugar, pectin and citric acid, and time of thermal treatment) on the volatile profile of these spreads with different formulations. The ripeness of the raw strawberries influences the concentrations of some of the compounds in the spreads, such as isobutyl acetate, butyl butyrate, 3-hexen-1-yl acetate or propan-2-ol. The process conditions have an important effect on the volatile profiles. Most of the esters and alcohols decreased whereas 13 new compounds appear, mostly furans (furfural, 2-acetylfurane, 5-methyl furfural, mesifurane) and aldehydes (octanal, nonanal, decanal and benzaldeyhde). In general, the spreads formulated with sucrose-isomaltulose that contained higher levels of pectin and citric acid gave better results in the preservation of the original aromatic compounds in raw strawberries.

  4. 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.

  5. 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.

  6. Space-weathering processes and products on volatile-rich asteroids

    NASA Astrophysics Data System (ADS)

    Britt, D.; Schelling, P.; Consolmagno, G.; Bradley, T.

    2014-07-01

    Space weathering is a generic term for the effects on atmosphereless solid bodies in the solar system from a range of processes associated with direct exposure to the space environment. These include impact processes (shock, vaporization, fragmentation, heating, melting, and ejecta formation), radiation damage (from galactic and solar cosmic rays), solar-wind effects (irradiation, ion implantation, and sputtering), and the chemical reactions driven by these processes. The classic example of space weathering is the formation of the lunar spectral red slope associated with the production of nanophase Fe (npFe0) in the dusty lunar regolith (C.R. Chapman, 2004, Annual Review of Earth & Planet. Sci. 32, C.M. Pieters, 2000, MAPS 35). Similar npFe0 has been recovered from asteroid (25143) Itokawa and some asteroid classes do exhibit modest spectral red slopes (T. Noguchi, 2011, Science 333). Space weathering can be thought of as driven by a combination of the chemical environment of space (hard vacuum, low oxygen fugacity, solar-wind implantation of hydrogen) along with thermal energy supplied by micrometeorite impacts. The forward modeling of space weathering as thermodynamically-driven decomposition of common rock-forming minerals suggests the production of a range of daughter products: (1) The silicate products typically lose oxygen, other volatile elements (i.e., sulfur and sodium), and metallic cations, producing minerals that are typically more disordered and less optically active than the original parent materials. (2) The decomposed metallic cations form in nano-sized blebs including npFe0, on the surfaces or in condensing rims of mineral grains. This creates a powerful optical component as seen in the lunar red slope. Surfaces with exposed npFe0 are an ideal environment for catalyzing further reactions. (3) The liberated volatile elements and gases (O, S, Na) may form an observable exosphere (e.g., Moon and Mercury) and can either escape from the body or

  7. Observed glacier and volatile distribution on Pluto from atmosphere-topography processes

    NASA Astrophysics Data System (ADS)

    Bertrand, Tanguy; Forget, François

    2016-12-01

    Pluto has a variety of surface frosts and landforms as well as a complex atmosphere. There is ongoing geological activity related to the massive Sputnik Planitia glacier, mostly made of nitrogen (N2) ice mixed with solid carbon monoxide and methane, covering the 4-kilometre-deep, 1,000-kilometre-wide basin of Sputnik Planitia near the anti-Charon point. The glacier has been suggested to arise from a source region connected to the deep interior, or from a sink collecting the volatiles released planetwide. Thin deposits of N2 frost, however, were also detected at mid-northern latitudes and methane ice was observed to cover most of Pluto except for the darker, frost-free equatorial regions. Here we report numerical simulations of the evolution of N2, methane and carbon monoxide on Pluto over thousands of years. The model predicts N2 ice accumulation in the deepest low-latitude basin and the threefold increase in atmospheric pressure that has been observed to occur since 1988. This points to atmospheric-topographic processes as the origin of Sputnik Planitia’s N2 glacier. The same simulations also reproduce the observed quantities of volatiles in the atmosphere and show frosts of methane, and sometimes N2, that seasonally cover the mid- and high latitudes, explaining the bright northern polar cap reported in the 1990s and the observed ice distribution in 2015. The model also predicts that most of these seasonal frosts should disappear in the next decade.

  8. Observed glacier and volatile distribution on Pluto from atmosphere-topography processes.

    PubMed

    Bertrand, Tanguy; Forget, François

    2016-12-01

    Pluto has a variety of surface frosts and landforms as well as a complex atmosphere. There is ongoing geological activity related to the massive Sputnik Planitia glacier, mostly made of nitrogen (N2) ice mixed with solid carbon monoxide and methane, covering the 4-kilometre-deep, 1,000-kilometre-wide basin of Sputnik Planitia near the anti-Charon point. The glacier has been suggested to arise from a source region connected to the deep interior, or from a sink collecting the volatiles released planetwide. Thin deposits of N2 frost, however, were also detected at mid-northern latitudes and methane ice was observed to cover most of Pluto except for the darker, frost-free equatorial regions. Here we report numerical simulations of the evolution of N2, methane and carbon monoxide on Pluto over thousands of years. The model predicts N2 ice accumulation in the deepest low-latitude basin and the threefold increase in atmospheric pressure that has been observed to occur since 1988. This points to atmospheric-topographic processes as the origin of Sputnik Planitia's N2 glacier. The same simulations also reproduce the observed quantities of volatiles in the atmosphere and show frosts of methane, and sometimes N2, that seasonally cover the mid- and high latitudes, explaining the bright northern polar cap reported in the 1990s and the observed ice distribution in 2015. The model also predicts that most of these seasonal frosts should disappear in the next decade.

  9. Formation of Volatile Tea Constituent Indole During the Oolong Tea Manufacturing Process.

    PubMed

    Zeng, Lanting; Zhou, Ying; Gui, Jiadong; Fu, Xiumin; Mei, Xin; Zhen, Yunpeng; Ye, Tingxiang; Du, Bing; Dong, Fang; Watanabe, Naoharu; Yang, Ziyin

    2016-06-22

    Indole is a characteristic volatile constituent in oolong tea. Our previous study indicated that indole was mostly accumulated at the turn over stage of oolong tea manufacturing process. However, formation of indole in tea leaves remains unknown. In this study, one tryptophan synthase α-subunit (TSA) and three tryptophan synthase β-subunits (TSBs) from tea leaves were isolated, cloned, sequenced, and functionally characterized. Combination of CsTSA and CsTSB2 recombinant protein produced in Escherichia coli exhibited the ability of transformation from indole-3-glycerol phosphate to indole. CsTSB2 was highly expressed during the turn over process of oolong tea. Continuous mechanical damage, simulating the turn over process, significantly enhanced the expression level of CsTSB2 and amount of indole. These suggested that accumulation of indole in oolong tea was due to the activation of CsTSB2 by continuous wounding stress from the turn over process. Black teas contain much less indole, although wounding stress is also involved in the manufacturing process. Stable isotope labeling indicated that tea leaf cell disruption from the rolling process of black tea did not lead to the conversion of indole, but terminated the synthesis of indole. Our study provided evidence concerning formation of indole in tea leaves for the first time.

  10. Influence of the fabrication process and fluoride content on the tribocorrosion behaviour of Ti6Al4V biomedical alloy in artificial saliva.

    PubMed

    Licausi, M P; Igual Muñoz, A; Amigó Borrás, V

    2013-04-01

    Titanium and its alloys are widely used as dental implants due to their low density, excellent biocompatibility, mechanical properties and corrosion resistance. However, during their lifetime Ti6Al4V biomedical alloys are subjected to different mechanical actions (i.e., sliding or fretting), thus resulting in a tribocorrosion system, which is an irreversible material degradation process due to the combined effect of corrosion and wear. In this study, the tribo-electrochemical behavior of cast and sintered (by powder metallurgy) Ti6Al4V alloy in artificial human saliva solution without and with fluoride additions of 100ppm and 1000ppm and in an average industrial mouth wash solution with a 112ppm fluoride content have been investigated by different electrochemical techniques. The same tribocorrosion mechanisms were found in the cast and sintered titanium alloys, although slightly different wear debris behavior was observed. At low applied passive potentials, wear rates are similar to those obtained under equilibrium conditions (Open Circuit Potential). There exists a critical fluoride concentration above which corrosion and tribocorrosion rates increase.

  11. Power consumption and byproducts in electron beam and electrical discharge processing of volatile organic compounds

    SciTech Connect

    Penetrante, B.M.; Hsiao, M.C.; Bardsley, J.N.

    1996-02-20

    Among the new methods being investigated for the post-process reduction of volatile organic compounds (VOCs) in atmospheric-pressure air streams are based on non-thermal plasmas. Electron beam, pulsed corona and dielectric-barrier discharge methods are among the more extensively investigated techniques for producing non-thermal plasmas. In order to apply non-thermal plasmas in an industrial scale, it is important to establish the electrical power requirements and byproducts of the process. In this paper the authors present experimental results using a compact electron beam reactor, a pulsed corona and a dielectric-barrier discharge reactor. They have used these reactors to study the removal of a wide variety of VOCs. The effects of background gas composition and gas temperature on the decomposition chemistry have been studied. They present a description of the reactions that control the efficiency of the plasma process. They have found that pulsed corona and other types of electrical discharge reactors are most suitable only for processes requiring O radicals. For VOCs requiring copious amounts of electrons, ions, N atoms or OH radicals, the use of electron beam reactors is generally the best way of minimizing the electrical power consumption. Electron beam processing is remarkably more effective for all of the VOCs tested. For control of VOC emissions from dilute, large volume sources such as paint spray booths, cost analysis shows that the electron beam method is cost-competitive to thermal and catalytic methods that employ heat recovery or hybrid techniques.

  12. Effect of post harvest radiation processing and storage on the volatile oil composition and glucosinolate profile of cabbage.

    PubMed

    Banerjee, Aparajita; Variyar, Prasad S; Chatterjee, Suchandra; Sharma, Arun

    2014-05-15

    Effect of radiation processing (0.5-2 kGy) and storage on the volatile oil constituents and glucosinolate profile of cabbage was investigated. Among the volatile oil constituents, an enhancement in trans-hex-2-enal was noted on irradiation that was attributed to the increased liberation of precursor linolenic acid mainly from monogalactosyl diacyl glycerol (MGDG). Irradiation also enhanced sinigrin, the major glucosinolate of cabbage that accounted for the enhanced allyl isothiocyanate (AITC) in the volatile oils of the irradiated vegetable. During storage the content of trans-hex-2-enal increased immediately after irradiation and then returned to the basal value within 24h while the content of sinigrin and AITC increased post irradiation and thereafter remained constant during storage. Our findings on the enhancement in potentially important health promoting compounds such as sinigrin and AITC demonstrates that besides extending shelf life and safety, radiation processing can have an additional advantage in improving the nutritional quality of cabbage.

  13. [Occurrence and distribution of volatile organic compounds in conventional and advanced drinking water treatment processes].

    PubMed

    Chen, Xi-Chao; Luo, Qian; Chen, Hu; Wei, Zi; Wang, Zi-Jian; Xu, Ke-Wen

    2013-12-01

    A series of experiments were conducted to study the occurrence and distribution of volatile organic compounds (VOCs) in conventional and advanced drinking water treatment processes of 3 water treatment plants in Lianyungang City. Results showed that 30 compounds of 3 classes were detected from 67 kinds of VOCs in all the samples collected. The concentrations of carbonyl compounds, halogenated hydrocarbons and benzenes detected were in the ranges of 0.04-61.27, 0.02-35.61 and 0.07-2.33 microg x L(-1) respectively. Comparing the changes of different VOCs in three drinking water treatment plants, conventional chlorination process could effectively remove benzenes but meanwhile produced trihalomethanes (THMs). Additional advanced treatment ozonation-biological activated carbon process could decrease the formation of THMs during pre-chlorination but produced new risky contaminants like carbonyl compounds. The changes of VOCs in tap water were also investigated. It was found that carbonyl compounds produced by ozonation could be further transformed to THMs with residual chlorine. However, the health risks of all detected compounds in tap water were at a low level, except that the carcinogenic risk of crotonaldehydes (9.3 x 10(-5)-2.2 x 10(-4)) was slightly higher than the US EPA threshold (10(-6)-10(-4)).

  14. Improved process model for ammonia volatilization from anaerobic swine lagoons under varying wind speeds and gas bubbling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ammonia volatilization from treatment lagoons varies widely with the lagoon water total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model using a...

  15. Changes in volatile flavor components of guava juice with high-pressure treatment and heat processing and during storage.

    PubMed

    Yen, G C; Lin, H T

    1999-05-01

    The changes in volatile flavor components of guava juice during pressure processing (25 degrees C, 600 MPa, 15 min), heat processing (95 degrees C, 5 min), and storage at 4 and 25 degrees C were evaluated by purge and trap/gas chromatography/mass spectrometry. Esters were the major volatile fraction in guava juice, and alcohols were the second. Pressure processing could maintain the original flavor distribution of the juice. Heat processing (95 degrees C, 5 min) caused decreases in the majority of flavor components in the juice when compared with freshly extracted juice. High-pressure treatment at 600 MPa for 15 min can effectively sterilize microbes but partially inactivate enzymes of guava juice; therefore, volatile components in pressure-treated juice gradually changed during storage periods. Pressure-treated guava juice showed increases in methanol, ethanol, and 2-ethylfuran with decreases in the other components during storage period. Nevertheless, the volatile distribution of 600 MPa treated guava juice was similar to that of freshly extracted juice when stored at 4 degrees C for 30 days.

  16. 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.

  17. [Emission characteristics and safety evaluation of volatile organic compounds in manufacturing processes of automotive coatings].

    PubMed

    Zeng, Pei-Yuan; Li, Jian-Jun; Liao, Dong-Qi; Tu, Xiang; Xu, Mei-Ying; Sun, Guo-Ping

    2013-12-01

    Emission characteristics of volatile organic compounds (VOCs) were investigated in an automotive coating manufacturing enterprise. Air samples were taken from eight different manufacturing areas in three workshops, and the species of VOCs and their concentrations were measured by gas chromatography-mass spectrometry (GC-MS). Safety evaluation was also conducted by comparing the concentration of VOCs with the permissible concentration-short term exposure limit (PC-STEL) regulated by the Ministry of Health. The results showed that fifteen VOCs were detected in the indoor air of the automotive coatings workshop, including benzene, toluene, ethylbenzene, xylene, ethyl acetate, butyl acetate, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, trimethylbenzene and ethylene glycol monobutyl ether, Their concentrations widely ranged from 0.51 to 593.14 mg x m(-3). The concentrations of TVOCs were significantly different among different manufacturing processes. Even in the same manufacturing process, the concentrations of each component measured at different times were also greatly different. The predominant VOCs of indoor air in the workshop were identified to be ethylbenzene and butyl acetate. The concentrations of most VOCs exceeded the occupational exposure limits, so the corresponding control measures should be taken to protect the health of the workers.

  18. 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.

  19. 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 ...

  20. 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 ...

  1. 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)

  2. Thermodynamic constants for actinide oxides and oxyhydroxides relevant to actinide volatility calculations for thermal oxidation processes

    SciTech Connect

    Ebbinghaus, B.B.; Krikorian, O.H.

    1993-10-27

    The purpose of this report is to provide input of thermodynamic data on actinide volatilities to EERC for use in their computer code for modeling of metal volatilities in incinerators. It is also anticipated that the data may be documented later in an EPA sponsored ``Metals Bible.`` It should be noted that only upper limits for the volatility of PuO{sub 2}(s) due to PuO{sub 3}(g) and PuO{sub 2}(OH){sub 2}(g) and the volatility of AmO{sub 2} in PuO{sub 2}(s) due to AmO{sub 3}(g) and AmO{sub 2}(OH){sub 2}(g) could be set. The data on the americium vapor species are intended for calculations where AmO{sub 2} is present as a solid solution in PuO{sub 2}(s).

  3. Implications of internal processes in the interpretation of Titan's volatile inventory measured by Cassini-Huygens

    NASA Astrophysics Data System (ADS)

    Tobie, Gabriel; Gautier, D.; Hersant, F.; Lunine, J. I.

    2010-04-01

    Based on a series of data collected by Cassini-Huygens, we constrain the composition of the primordial bricks that formed Titan and quantify the chemical exchanges that occurred on Titan between the interior and the atmosphere since its accretion. Assuming that the bricks that formed Titan had a composition close to that of Enceladus and that of the planetesimals in the feeding zone of Saturn, we show that accretional melting generate an CH4-CO2-H2S - dominated atmosphere of more than 10 bars in equilibrium with a water ocean. The partial atmospheric pressure of ammonia remains low (< 0.01 bar for T< 300 K) owing to its high solubility in liquid water. Photochemical conversion of atmospheric ammonia into nitrogen is possible just after accretion but requires the water ocean remains in contact with the atmosphere during at least 10-50 millions of years. We show that most of the gas species, except N2 and 36Ar, released during accretion are likely to be re-incorporated in the interior during the post-accretional cooling phase, owing to efficient clathration at the water/ocean interface. During this process, xenon is predicted to be almost entirely removed from the primitive atmosphere and to be stored in the form of clathrate hydrate in the interior. The composition of gases released during the rest of the evolution is determined by the stability of each gas species relative to the clathrate phase and is expected to be dominated by CH4 and CO2, and to contain small amounts of argon and CO. It can be anticipated from our analysis that flows and deposits of CO2-rich materials would be associated to cryovolcanic events. Although the detection of 40Ar clearly support that interaction with the silicate phase has occurred during Titan's history, it is still unclear if significant chemical exchanges has occurred with the rocky core. Only detection of 38Ar and of the other noble gas isotopes by a future mission will permit to determine how the silicate phase has contributed

  4. Occupational exposure to volatile nitrosamines in foundries using the Ashland core-making process

    SciTech Connect

    Ducos, P.; Gaudin, R.; Maire, C.; Mavelle, T.; Bouchikhi, B.; Derby, G.

    1988-10-01

    Eight foundries using the Ashland process for the production of cores were surveyed to assess the occupational exposure to carcinogenic volatile nitrosamines. Personal and area samples were collected by means of artifact-free cartridges during the core-making and the molding/casting/shake-out operations. Analyses were carried out with gas chromatography/Hall detector and gas chromatography/TEA (thermal energy analyzer) for validation. The core-making workshops had the highest concentration for at least two nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosoethylmethylamine (NEMA), but the levels of NDMA never exceeded 0.35 microgram/m3 with an arithmetic mean between 0.23 and 0.02 microgram/m3. In a number of samplings, two other peaks, both on TEA and Hall detector, could not be identified. The foundries per se (molding/casting/shake-out) had lower nitrosamine levels (CNDMAmax = 0.15 microgram/m3, CNDMA less than 0.03 microgram/m3). For the first time NEMA was identified as an industrial contaminant in foundries but its concentration was always lower than that of NDMA. The nitrosamines found were presumably produced from dimethylethylamine (DMEA). Industries producing or using tertiary or secondary amines should be controlled for their possible nitrosamine contamination.

  5. Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes

    USGS Publications Warehouse

    Humphreys, Madeleine C.S.; Brooker, R; Fraser, D.C.; Burgisser, A; Mangan, Margaret T.; McCammon, C

    2015-01-01

    Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and degassing of volatile-rich magmas. This study sets out to investigate the effect of disequilibrium crustal processes that may involve coupled changes in H2O content and Fe oxidation state, by examining the degassing and hydration of sulphur-free rhyolites. We show that experimentally hydrated melts record strong increases in Fe3+/∑Fe with increasing H2O concentration as a result of changes in water activity. This is relevant for the passage of H2O-undersaturated melts from the deep crust towards shallow crustal storage regions, and raises the possibility that vertical variations in fO2 might develop within arc crust. Conversely, degassing experiments produce an increase in Fe3+/∑Fe with decreasing H2O concentration. In this case the oxidation is explained by loss of H2 as well as H2O into bubbles during decompression, consistent with thermodynamic modelling, and is relevant for magmas undergoing shallow degassing en route to the surface. We discuss these results in the context of the possible controls on fO2 during the generation, storage and ascent of magmas in arc settings, in particular considering the timescales of equilibration relative to observation as this affects the quality of the petrological record of magmatic fO2.

  6. 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. ...

  7. Bio-electrolytic sensor for rapid monitoring of volatile fatty acids in anaerobic digestion process.

    PubMed

    Jin, Xiangdan; Li, Xiaohu; Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

    2017-03-15

    This study presents an innovative biosensor that was developed on the basis of a microbial electrolysis cell for fast and reliable measurement of volatile fatty acids (VFA) during anaerobic digestion (AD) process. The bio-electrolytic sensor was first tested with synthetic wastewater containing varying concentrations of VFA. A linear correlation (R(2) = 0.99) between current densities (0.03 ± 0.01 to 2.43 ± 0.12 A/m(2)) and VFA concentrations (5-100 mM) was found. The sensor performance was then investigated under different affecting parameters such as the external voltage, VFA composition ratio, and ionic strength. Linear relationship between the current density and VFA concentrations was always observed. Furthermore, the bio-electrolytic sensor proved ability to handle interruptions such as the presence of complex organic matter, anode exposure to oxygen and low pH. Finally, the sensor was applied to monitor VFA concentrations in a lab-scale AD reactor for a month. The VFA measurements from the sensor correlated well with those from GC analysis which proved the accuracy of the system. Since hydrogen was produced in the cathode as byproduct during monitoring, the system could be energy self-sufficient. Considering the high accuracy, short response time, long-term stability and additional benefit of H2 production, this bio-electrolytic sensor could be a simple and cost-effective method for VFA monitoring during AD and other anaerobic processes.

  8. 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.

  9. Influence of partial replacement of NaCl with KCl on profiles of volatile compounds in dry-cured bacon during processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the influence of partial substitution of NaCl with KCl on the formation of volatile compounds in bacons during processing using a purge and trap dynamic headspace GC/MS system. Three substitutions were 0% KCl (I), 40% KCl (II), and 70% KCl (III). The profiles of the volatile ...

  10. 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

  11. APPLICATION OF VACUUM SALT DISTILLATION TECHNOLOGY FOR THE REMOVAL OF FLUORIDE

    SciTech Connect

    Pierce, R.; Pak, D.

    2011-08-10

    Vacuum distillation of chloride salts from plutonium oxide (PuO{sub 2}) and simulant PuO{sub 2} has been previously demonstrated at Department of Energy (DOE) sites using kilogram quantities of chloride salt. The apparatus for vacuum distillation contains a zone heated using a furnace and a zone actively cooled using either recirculated water or compressed air. During a vacuum distillation operation, a sample boat containing the feed material is placed into the apparatus while it is cool, and the system is sealed. The system is evacuated using a vacuum pump. Once a sufficient vacuum is attained, heating begins. Volatile salts distill from the heated zone to the cooled zone where they condense, leaving behind the non-volatile materials in the feed boat. The application of vacuum salt distillation (VSD) is of interest to the HB-Line Facility and the MOX Fuel Fabrication Facility (MFFF) at the Savannah River Site (SRS). Both facilities are involved in efforts to disposition excess fissile materials. Many of these materials contain chloride and fluoride salt concentrations which make them unsuitable for dissolution without prior removal of the chloride and fluoride salts. Between September 2009 and January 2011, the Savannah River National Laboratory (SRNL) and HB-Line designed, developed, tested, and successfully deployed a system for the distillation of chloride salts. Subsequent efforts are attempting to adapt the technology for the removal of fluoride. Fluoride salts of interest are less-volatile than the corresponding chloride salts. Consequently, an alternate approach is required for the removal of fluoride without significantly increasing the operating temperature. HB-Line Engineering requested SRNL to evaluate and demonstrate the feasibility of an alternate approach using both non-radioactive simulants and plutonium-bearing materials. Whereas the earlier developments targeted the removal of sodium chloride (NaCl) and potassium chloride (KCl), the current

  12. Nitrogen compounds in must and volatile profile of white wine: Influence of clarification process before alcoholic fermentation.

    PubMed

    Burin, Vívian Maria; Caliari, Vinícius; Bordignon-Luiz, Marilde T

    2016-07-01

    The aim of this study was to investigate the effect of adding a fining agent to the must in relation to the fermentation kinetics and the volatile composition of the wine produced. Three fining agents, bentonite, pectinolytic enzyme and silica were applied, separately, to samples of Chardonnay must. It was observed that the addition of a fining agent had a significant influence on the must and wine composition. The must clarified with bentonite showed the lowest nitrogen content and the enzyme addition led to the highest nitrogen content. During the fermentation process, a difference in the consumption rate was observed for each amino acid in relation to the fining agent used in the process. In relation to the volatile composition, the wine produced had different characteristics according to the fining agent added to the must, which was confirmed by separation of the samples using principal component analysis.

  13. 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.

  14. Manufacture and properties of fluoride cement

    NASA Astrophysics Data System (ADS)

    Malata-Chirwa, Charles David

    process. It was observed in the laboratory simulated production of fluoride cement, that the clinkering temperature is much lower (around 1 170 °C) compared to that for the production of ordinary Portland cement. The other observed differences were attributed to the different mineralogical composition as a result of fluoride incorporation into the cement. While fluorine content is very minimal in fluoride cement, not more than 2 %, the resulting cementitious products are altered significantly as was observed from the study. Part of the experimental results has been used as reference material in the preparation of a draft Malawi Standard on fluoride cement. This draft standard will be submitted to the Malawi Bureau of Standards for further processing before it can be officially endorsed as a Malawi Standard.

  15. Profiling analysis of volatile compounds from fruits using comprehensive two-dimensional gas chromatography and image processing techniques.

    PubMed

    Schmarr, Hans-Georg; Bernhardt, Jörg

    2010-01-22

    An image processing approach originating from the proteomics field has been transferred successfully to the processing of data obtained with comprehensive two-dimensional gas chromatographic separations data. The approach described here has proven to be a useful analytical tool for unbiased pattern comparison or profiling analyses, as demonstrated with the differentiation of volatile patterns ("aroma") from fruits such as apples, pears, and quince fruit. These volatile patterns were generated by headspace solid phase microextraction coupled to comprehensive two-dimensional gas chromatography (HS-SPME-GC x GC). The data obtained from GC x GC chromatograms were used as contour plots which were then converted to gray-scale images and analyzed utilizing a workflow derived from 2D gel-based proteomics. Run-to-run variations between GC x GC chromatograms, respectively their contour plots, have been compensated by image warping. The GC x GC images were then merged into a fusion image yielding a defined and project-wide spot (peak) consensus pattern. Within detected spot boundaries of this consensus pattern, relative quantities of the volatiles from each GC x GC image have been calculated, resulting in more than 700 gap free volatile profiles over all samples. These profiles have been used for multivariate statistical analysis and allowed clustering of comparable sample origins and prediction of unknown samples. At present state of development, the advantage of using mass spectrometric detection can only be realized by data processing off-line from the identified software packages. However, such information provides a substantial basis for identification of statistically relevant compounds or for a targeted analysis.

  16. Fates of chlorinated volatile organic compounds in aerobic biological treatment processes: the effects of aeration and sludge addition.

    PubMed

    Chen, Wei-Hsiang; Yang, Wen-Ben; Yuan, Chung-Shin; Yang, Jun-Chen; Zhao, Qing-Liang

    2014-05-01

    The emission of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs) is becoming an environmental issue of increasing concern. As biological treatment has been considered as one important approach for VOC removal, lab-scale batch experiments were conducted in this study to investigate the fates of four chlorinated hydrocarbons, including chloroform, carbon tetrachloride, trichloroethylene (TCE), and tetrachloroethylene (PERC), in the biological treatment processes with respect to the effects of aeration and sludge addition. The VOC concentrations in the phases of air, water, and sludge under four simulated treatment stages (the first sedimentation, the forepart and rear part of aerobic biological treatment, and the second sedimentation) were analyzed. The results were used to understand the three-phase partitioning of these compounds and to estimate their potentials for volatilization and biological sorption and degradation in these technologies with the concept of fugacity. It was observed that the VOCs were mainly present in the water phase through the experiments. The effects of aeration or sludge addition on the fates of these VOCs occurred but appeared to be relatively limited. The concentration distributions of the VOCs were well below the reported partitioning coefficients. It was suggested that these compounds were unsaturated in the air and sludge phases, enhancing their potentials for volatilization and biological sorption/degradation through the processes. However, the properties of these chlorinated VOCs such as the volatility, polarity, or even biodegradability caused by their structural characteristics (e.g., the number of chlorine, saturated or unsaturated) may represent more significant factors for their fates in the aerobic biological treatment processes. These findings prove the complication behind the current knowledge of VOC pollutions in WWTPs and are of help to manage the adverse impacts on the environment and public

  17. A process-based emission model of volatile organic compounds from silage sources on farms

    NASA Astrophysics Data System (ADS)

    Bonifacio, H. F.; Rotz, C. A.; Hafner, S. D.; Montes, F.; Cohen, M.; Mitloehner, F. M.

    2017-03-01

    Silage on dairy farms can emit large amounts of volatile organic compounds (VOCs), a precursor in the formation of tropospheric ozone. Because of the challenges associated with direct measurements, process-based modeling is another approach for estimating emissions of air pollutants from sources such as those from dairy farms. A process-based model for predicting VOC emissions from silage was developed and incorporated into the Integrated Farm System Model (IFSM, v. 4.3), a whole-farm simulation of crop, dairy, and beef production systems. The performance of the IFSM silage VOC emission model was evaluated using ethanol and methanol emissions measured from conventional silage piles (CSP), silage bags (SB), total mixed rations (TMR), and loose corn silage (LCS) at a commercial dairy farm in central California. With transport coefficients for ethanol refined using experimental data from our previous studies, the model performed well in simulating ethanol emission from CSP, TMR, and LCS; its lower performance for SB could be attributed to possible changes in face conditions of SB after silage removal that are not represented in the current model. For methanol emission, lack of experimental data for refinement likely caused the underprediction for CSP and SB whereas the overprediction observed for TMR can be explained as uncertainty in measurements. Despite these limitations, the model is a valuable tool for comparing silage management options and evaluating their relative effects on the overall performance, economics, and environmental impacts of farm production. As a component of IFSM, the silage VOC emission model was used to simulate a representative dairy farm in central California. The simulation showed most silage VOC emissions were from feed lying in feed lanes and not from the exposed face of silage storages. This suggests that mitigation efforts, particularly in areas prone to ozone non-attainment status, should focus on reducing emissions during feeding. For

  18. SCREENING PROCESSED MILK FOR VOLATILE ORGANIC COMPOUNDS USING VACUUM DISTILLATION/GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    EPA Science Inventory

    An adaptation of Office of Solid Waste and Emergency Response' Test Methods for Evaluating Solid Waste Physical/Chemical Methods (SW-846) method 8261 to analyze milk for an expanded list of volatile organic compounds is presented. The milk matriz exhibits a strong affinity for o...

  19. Thermogenic respiratory processes drive the exponential increase of volatile organic compound emissions in Macrozamia cycad cones.

    PubMed

    Terry, L Irene; Roemer, Robert B; Booth, David T; Moore, Chris J; Walter, Gimme H

    2016-07-01

    An important outcome of plant thermogenesis is increased emissions of volatiles that mediate pollinator behaviour. We investigated whether the large increase in emissions, mainly the monoterpene ß-myrcene (>90%), during daily thermogenic events of Macrozamia macleayi and lucida cycad cones are due solely to the influence of high cone temperatures or are, instead, a result of increased respiratory rates during thermogenesis. We concurrently measured temperature, oxygen consumption and ß-myrcene emission profiles during thermogenesis of pollen cones under typical environmental temperatures and during experimental manipulations of cone temperatures and aerobic conditions, all in the dark. The exponential rise in ß-myrcene emissions never occurred without a prior, large increase in respiration, whereas an increase in cone temperature alone did not increase emissions. When respiration during thermogenesis was interrupted by anoxic conditions, ß-myrcene emissions decreased. The increased emission rates are not a result of increased cone temperature per se (through increased enzyme activity or volatilization of stored volatiles) but are dependent on biosynthetic pathways associated with increased respiration during thermogenesis that provide the carbon, energy (ATP) and reducing compounds (NADPH) required for ß-myrcene production through the methylerythritol phosphate (MEP) pathway. These findings establish the significant contribution of respiration to volatile production during thermogenesis.

  20. Changes in physico-chemical properties and volatile compounds throughout the manufacturing process of dry-cured foal loin.

    PubMed

    Lorenzo, José M; Carballo, J

    2015-01-01

    Physico-chemical, textural, lipolytic and volatile compound changes that occur during the manufacture of dry-cured foal loin were studied. Hardness and chewiness increased significantly (P<0.001) from 1.67 kg and 0.48 kg ∗ mm to 18.33 kg and 5.01 kg∗mm, respectively during ripening process. The total average content of free fatty acid increased significantly (P<0.001), from 768.8 mg/100g of fat in the loins immediately after the seasoning period to 1271.1mg/100g of fat at the end of the drying-ripening period. In the final product, aldehydes became the dominant volatile compounds.

  1. Temporal variation, regional sources, and removal processes of volatile organic compounds in New England

    NASA Astrophysics Data System (ADS)

    Russo, Rachel S.

    This dissertation describes three research projects with the common objective of characterizing the influence of volatile organic compounds (VOCs) on air quality in New England using measurements made over multiple years (2002-2008) and from different sampling locations. The specific objectives include identifying sources (direct emission or secondary production), quantifying mixing ratios, and characterizing the chemical (i.e., oxidation, photolysis) and physical (i.e., transport, mixing) processes which regulate the distributions of VOCs in the troposphere over southeastern New Hampshire. Chapters 2 and 3 discuss the seasonal and interannual variability of nonmethane hydrocarbons (NMHCs), selected halocarbons, and alkyl nitrates using measurements from canister samples collected at Thompson Farm in Durham, NH throughout January 2004-February 2008. Several anthropogenic and biogenic sources of NMHCs and halocarbons were identified based on correlations with tracer compounds and comparisons with source signatures. Additionally, evidence for the dry deposition of alkyl nitrates of night was observed which is a previously unaccounted for removal mechanism. Analysis of alkyl nitrate/parent hydrocarbon ratios, measurements made onboard the NOAA R/V Ronald H. Brown during the 2002 New England Air Quality Study, and canister samples collected throughout the Great Bay estuary in August 2003 are presented to assess the relative contributions of anthropogenic and marine sources of alkyl nitrates. The research described in Chapter 4 used measurements of VOCs made at an inland (Thompson Farm) and an offshore (Appledore Island) site to identify evidence of chlorine initiated oxidation of VOCs, estimate chlorine atom (Cl) concentrations during two summers and for different transport sectors, and assess the potential influence of chlorine chemistry on the oxidative capacity of the troposphere over coastal New Hampshire. Comparable Cl concentrations were estimated using a novel

  2. Measurement of plutonium and americium volatilities under thermal process conditions. Final report

    SciTech Connect

    Krikorian, O.H.; Condit, R.H.; Fontes, A.S. Jr.; Fleming, D.L.; Magana, J.W.; Morris, W.F.; Adamson, M.G.

    1993-04-28

    We have used the transpiration method to measure volatilities of Pu and Am from PuO{sub 2}(s) and PuO{sub 2}/2% AmO{sub 2}(s) in the presence of steam and oxygen at temperatures of 1230--1430 K. We find the volatile species to be PuO{sub 2}(OH){sub 2}(g) and AmO{sub 2}(OH){sub 2}(g) at vapor pressures on the order of 10{sup {minus}10} atm and 10 {sup {minus}12} atm respectively under measurement conditions. For the Pu volatilization reaction, PuO{sub 2}(s) + 1/2 0{sub 2}(9) + H{sub 2}0(g) = PuO{sub 2}(OH){sub 2}(g), we obtain a free energy of reaction of {Delta}G{sup O}{sub T} = 231.3--0.0109 T in kj/mol, and for the Am volatilization reaction, AmO{sub 2}(s.s. in PuO{sub 2}) + 1/2 0{sub 2}(9) + H{sub 2}0(g) = AmO{sub 2}(OH){sub 2}(g), we obtain AG{sup O}{sub T} = 223.9--0.0109 T in kj/mol. We apply these results to the Rocky Flats Plant Fluidized Bed Incinerator to assess the amount of volatile Pu and Am produced in the secondary combustor chamber. Taking operating conditions of 550C combustor temperature, 40 kmols/h of total gas flow at 1 atm pressure, 0.1 atm 0{sub 2}(9), 0.05 atm H{sub 2}0(g), PuO{sub 2} (s) containing 200 ppm AmO{sub 2} in the bed, and 6000 h of operating time per year, gives volatilization rates of 7 {times} 10 {sup {minus}6}g Pu and 4 {times} 10 {sup {minus}9}g Am/y.

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

    PubMed

    Rirattanapong, Opas; Rirattanapong, Praphasri

    2016-01-01

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

  4. Zirconium fluoride glass - Surface crystals formed by reaction with water

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

    1984-01-01

    The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

  5. From quantum mechanics to finance: Microfoundations for jumps, spikes and high volatility phases in diffusion price processes

    NASA Astrophysics Data System (ADS)

    Henkel, Christof

    2017-03-01

    We present an agent behavior based microscopic model that induces jumps, spikes and high volatility phases in the price process of a traded asset. We transfer dynamics of thermally activated jumps of an unexcited/excited two state system discussed in the context of quantum mechanics to agent socio-economic behavior and provide microfoundations. After we link the endogenous agent behavior to price dynamics we establish the circumstances under which the dynamics converge to an Itô-diffusion price processes in the large market limit.

  6. Characteristics of yttrium fluoride and yttrium oxide coatings for plasma process equipment prepared by atmospheric plasma spraying

    NASA Astrophysics Data System (ADS)

    Lin, Tzu-Ken; Wuu, Dong-Sing; Huang, Shih-Yung; Wang, Wei-Kai

    2016-12-01

    In this study, yttrium fluoride (YF3) and yttrium oxide (Y2O3) coatings were prepared by an atmospheric plasma spraying technique and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). YF3 powders were sprayed at various plasma spraying powers of 9, 15, and 21 kW. The XRD result indicates that the YF3 coating shows preferred orientations and was well crystallized. The XPS results revealed a strong Y-F bond on the YF3 coating surface. A porosity value analysis showed that the porosity of the YF3 coating was lower than that of the Y2O3 coating. Moreover, the dielectric strength of the YF3 coating (22.65 kV/mm) was higher than that of the Y2O3 coating (14.42 kV/mm). This confirms that the YF3 coating exhibits a breakdown voltage of 4.97 kV, which is more than 1.5 times higher than that observed for the Y2O3 coating (3.29 kV). These results indicate that the YF3 coating has better mechanical and dielectric properties than the Y2O3 coating, indicating that the YF3 coating is a very attractive novel antiplasma and corrosion-resistant material.

  7. APPLICATION OF VACUUM SALT DISTILLATION TECHNOLOGY FOR THE REMOVAL OF FLUORIDE AND CHLORIDE FROM LEGACY FISSILE MATERIALS

    SciTech Connect

    Pierce, R.; Peters, T.

    2011-11-01

    Between September 2009 and January 2011, the Savannah River National Laboratory (SRNL) and the Savannah River Site (SRS) HB-Line Facility designed, developed, tested, and successfully deployed a production-scale system for the distillation of sodium chloride (NaCl) and potassium chloride (KCl) from plutonium oxide (PuO{sub 2}). Subsequent efforts adapted the vacuum salt distillation (VSD) technology for the removal of chloride and fluoride from less-volatile halide salts at the same process temperature and vacuum. Calcium chloride (CaCl{sub 2}), calcium fluoride (CaF{sub 2}), and plutonium fluoride (PuF{sub 3}) were of particular concern. To enable the use of the same operating conditions for the distillation process, SRNL employed in situ exchange reactions to convert the less-volatile halide salts to compounds that facilitated the distillation of halide without removal of plutonium. SRNL demonstrated the removal of halide from CaCl{sub 2}, CaF{sub 2} and PuF{sub 3} below 1000 C using VSD technology.

  8. 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.

  9. 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.

  10. Impact of thermal and nonthermal processing technologies on unfermented apple cider aroma volatiles.

    PubMed

    Azhu Valappil, Zareena; Fan, Xuetong; Zhang, Howard Q; Rouseff, Russell L

    2009-02-11

    Aroma composition and microbial quality of identical lots of apple cider treated by pulsed electric field (PEF), ultraviolet irradiation (UV), or thermal pasteurization stored at 4 degrees C were compared at 0 and 4 weeks. Conditions were optimized to achieve identical 5 log reductions in Escherichia coli K12 for each treatment. PEF and thermal pasteurization maintained acceptable microbial quality for 4 weeks, but UV samples fermented after 2 weeks. Twenty-eight volatiles were quantified using gas chromatography-mass spectrometry (GC-MS) and odor activity values (OAV) determined. OAVs of 69:hexyl acetate, 41:hexanal, 25:2-methylbutyl acetate, 23:2-methyl ethyl butyrate, and 14:2-(E)-hexenal were observed for the control cider. Significant differences (p < 0.05) in the levels of these odorants were observed between treated apple ciders only after 4 weeks of storage. Thermal samples lost 30% of the major ester and aldehyde volatiles during storage with significant decreases (p < 0.05) in butyl acetate, 2-methylbutyl acetate, hexanal, and 2-(E)-hexenal. In UV cider, hexanal and 2-(E)-hexenal were completely lost after 4 weeks of storage. Microbial spoilage in UV cider after 4 weeks of storage was chemically confirmed by the detection of the microbial metabolite 1,3-pentadiene. PEF cider lost <2% of its total ester and aldehydes after 4 weeks of storage and was preferred by 91% of the sensory panel over thermally treated cider.

  11. 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.

  12. 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.

  13. 40 CFR 60.202 - 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. 60.202 Section... Industry: Wet-Process Phosphoric Acid Plants § 60.202 Standard for fluorides. (a) On and after the date on... facility any gases which contain total fluorides in excess of 10.0 g/Mg of equivalent P2O5 feed (0.020...

  14. 40 CFR 60.202 - 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. 60.202 Section... Industry: Wet-Process Phosphoric Acid Plants § 60.202 Standard for fluorides. (a) On and after the date on... facility any gases which contain total fluorides in excess of 10.0 g/Mg of equivalent P2O5 feed (0.020...

  15. ALH85085: a unique volatile-poor carbonaceous chondrite with possible implications for nebular fractionation processes

    USGS Publications Warehouse

    Grossman, J.N.; Rubin, A.E.; MacPherson, G.J.

    1988-01-01

    Allan Hills 85085 is a unique chondrite with affinities to the Al Rais-Renazzo clan of carbonaceous chondrites. Its constituents are less than 50 ??m in mean size. Chondrules and microchondrules of all textures are present; nonporphyritic chondrules are unusually abundant. The mean compositions of porphyritic, nonporphyritic and barred olivine chondrules resemble those in ordinary chondrites except that they are depleted in volatile elements. Ca-, Al-rich inclusions are abundant and largely free of nebular alteration; they comprise types similar to those in CM and CO chondrites, as well as unique types. Calcium dialuminate occurs in several inclusions. Metal, silicate and sulfide compositions are close to those in CM-CO chondrites and Al Rais and Renazzo. C1-chondrite clasts and metal-rich "reduced" clasts are present, but opaque matrix is absent. Siderophile abundances in ALH85085 are extremely high (e.g., Fe Si = 1.7 ?? solar), and volatiles are depleted (e.g., Na Si = 0.25 ?? solar, S Si = 0.03 ?? solar). Nonvolatile lithophile abundances are similar to those in Al Rais, Renazzo, and CM and CO chondrites. ALH85085 agglomerated when temperatures in the nebula were near 1000 K, in the same region where Renazzo, Al Rais and the CI chondrites formed. Agglomeration of high-temperature material may thus be a mechanism by which the fractionation of refractory lithophiles occurred in the nebula. Chondrule formation must have occurred at high temperatures when clumps of precursors were small. After agglomeration, ALH85085 was annealed and lightly shocked. C1 and other clasts were subsequently incorporated during late-stage brecciation. ?? 1988.

  16. 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.

  17. Flavor characteristics of the juices from fresh market tomatoes differentiated from those from processing tomatoes by combined analysis of volatile profiles with sensory evaluation.

    PubMed

    Iijima, Yoko; Iwasaki, Yumi; Otagiri, Yuji; Tsugawa, Hiroshi; Sato, Tsuneo; Otomo, Hiroe; Sekine, Yukio; Obata, Akio

    2016-12-01

    Various commercial tomato juices with different flavors are available at markets worldwide. To clarify the marker compounds related to the flavor characteristics of tomato juice, we analyzed 15 pure commercial tomato juices by a combination of volatile profiling and sensory evaluation. The correlations among volatiles and the relationship between volatiles and sensory descriptors were elucidated by multivariate analyses. Consequently, the tomato juices made from fresh market tomatoes (including the popular Japanese tomato variety "Momotaro") were clearly separated from other juices made from processing tomatoes, by both the volatile composition and sensory profiles. cis-3-Hexenol, hexanal, and apocarotenoids negatively contributed to the juices from fresh market tomatoes, whereas Strecker aldehydes and furfural showed positive contributions to the juices. Accordingly, the sensory characteristics of juices from fresh market tomatoes were related to cooked and fruity flavors but not to green or fresh notes.

  18. 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.

  19. Charge-trap non-volatile memories fabricated by laser-enabled low-thermal budget processes

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Hsien; Shieh, Jia-Min; Pan, Fu-Ming; Yang, Chih-Chao; Shen, Chang-Hong; Wang, Hsing-Hsiang; Hsieh, Tung-Ying; Wu, Ssu-Yu; Wu, Meng-Chyi

    2015-11-01

    We fabricated charge-trap non-volatile memories (NVMs) using low thermal budget processes, including laser-crystallization of poly-Si thin film, chemical vapor deposition deposition of a stacked memory layer, and far-infrared-laser dopant activation. The thin poly-Si channel has a low defect-density at the interface with the bulk, resulting in a steep subthreshold swing for the NVM transistors. The introduction of the stacked SiO2/AlOxNy tunnel layer and the SiNx charge-trap layer with a gradient bandgap leads to reliable retention and endurance at low voltage for the NVMs. The low thermal budget processes are desirable for the integration of the nano-scaled NVMs into system on panels.

  20. Volatile Metabolites

    PubMed Central

    Rowan, Daryl D.

    2011-01-01

    Volatile organic compounds (volatiles) comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals) both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites. PMID:24957243

  1. Vehicular volatile organic compounds losses due to refueling and diurnal process in China: 2010-2050.

    PubMed

    Yang, Xiaofan; Liu, Huan; Cui, Hongyang; Man, Hanyang; Fu, Mingliang; Hao, Jiming; He, Kebin

    2015-07-01

    Volatile organic compounds (VOCs) are crucial to control air pollution in major Chinese cities since VOCs are the dominant factor influencing ambient ozone level, and also an important precursor of secondary organic aerosols. Vehicular evaporative emissions have become a major and growing source of VOC emissions in China. This study consists of lab tests, technology evaluation, emissions modeling, policy projections and cost-benefit analysis to draw a roadmap for China for controlling vehicular evaporative emissions. The analysis suggests that evaporative VOC emissions from China's light-duty gasoline vehicles were approximately 185,000 ton in 2010 and would peak at 1,200,000 ton in 2040 without control. The current control strategy implemented in China, as shown in business as usual (BAU) scenario, will barely reduce the long-term growth in emissions. Even if Stage II gasoline station vapor control policies were extended national wide (BAU+extended Stage II), there would still be over 400,000 ton fuel loss in 2050. In contrast, the implementation of on-board refueling vapor recovery (ORVR) on new cars could reduce 97.5% of evaporative VOCs by 2050 (BAU+ORVR/BAU+delayed ORVR). According to the results, a combined Stage II and ORVR program is a comprehensive solution that provides both short-term and long-term benefits. The net cost to achieve the optimal total evaporative VOC control is approximately 62 billion CNY in 2025 and 149 billion CNY in 2050.

  2. Volatile organic compounds in Arctic snow: concentrations and implications for atmospheric processes.

    PubMed

    Kos, Gregor; Kanthasami, Visahini; Adechina, Nafissa; Ariya, Parisa A

    2014-11-01

    The role of volatile organic compounds (VOC) in the snowpack for atmospheric oxidation, gas-particle transfer and aerosol formation remains poorly understood, partly due to a lack of methodology and unavailable data. We deployed solid phase micro-extraction (SPME) gas chromatography with flame ionization detection for measurement of halogenated, aromatic and oxygenated VOC in the snow pack in Alert, NU, Canada, a High Arctic site. Maximum concentrations in snow were 39 ± 6 μg L(-1) (styrene), indicating a potential VOC contribution to atmospheric oxidation and aerosol formation. Concurrently sampled air had concentrations of up to 1.0 ± 0.3 ng L(-1) (trichloroethene). Back trajectory data showed a change of air mass source region during a depletion event of several VOC in snow (e.g., trichloroethene and benzene). Snow profiles showed an enrichment of most compounds close to the surface. During a second study in Barrow, AK, USA VOC were quantified in snow and frost flowers in the Montreal lab. In Barrow work was carried out as part of the extensive OASIS (Ocean-Atmosphere-Sea Ice-Snowpack) field campaign. Maximum VOC concentrations were up to 1.3 ± 0.1 μg L(-1) (acetophenone). Bromoform in frost flowers averaged 0.19 ± 0.04 μg L(-1), indicating the potential to contribute to bromine generation through photolysis.

  3. The Search for a Volatile Human Specific Marker in the Decomposition Process.

    PubMed

    Rosier, E; Loix, S; Develter, W; Van de Voorde, W; Tytgat, J; Cuypers, E

    2015-01-01

    In this study, a validated method using a thermal desorber combined with a gas chromatograph coupled to mass spectrometry was used to identify the volatile organic compounds released during decomposition of 6 human and 26 animal remains in a laboratory environment during a period of 6 months. 452 compounds were identified. Among them a human specific marker was sought using principle component analysis. We found a combination of 8 compounds (ethyl propionate, propyl propionate, propyl butyrate, ethyl pentanoate, pyridine, diethyl disulfide, methyl(methylthio)ethyl disulfide and 3-methylthio-1-propanol) that led to the distinction of human and pig remains from other animal remains. Furthermore, it was possible to separate the pig remains from human remains based on 5 esters (3-methylbutyl pentanoate, 3-methylbutyl 3-methylbutyrate, 3-methylbutyl 2-methylbutyrate, butyl pentanoate and propyl hexanoate). Further research in the field with full bodies has to corroborate these results and search for one or more human specific markers. These markers would allow a more efficiently training of cadaver dogs or portable detection devices could be developed.

  4. Change in Color and Volatile Composition of Skim Milk Processed with Pulsed Electric Field and Microfiltration Treatments or Heat Pasteurization.

    PubMed

    Chugh, Anupam; Khanal, Dipendra; Walkling-Ribeiro, Markus; Corredig, Milena; Duizer, Lisa; Griffiths, Mansel W

    2014-04-23

    Non-thermal processing methods, such as pulsed electric field (PEF) and tangential-flow microfiltration (TFMF), are emerging processing technologies that can minimize the deleterious effects of high temperature short time (HTST) pasteurization on quality attributes of skim milk. The present study investigates the impact of PEF and TFMF, alone or in combination, on color and volatile compounds in skim milk. PEF was applied at 28 or 40 kV/cm for 1122 to 2805 µs, while microfiltration (MF) was conducted using membranes with three pore sizes (lab-scale 0.65 and 1.2 µm TFMF, and pilot-scale 1.4 µm MF). HTST control treatments were applied at 75 or 95 °C for 20 and 45 s, respectively. Noticeable color changes were observed with the 0.65 µm TFMF treatment. No significant color changes were observed in PEF-treated, 1.2 µm TFMF-treated, HTST-treated, and 1.4 µm MF-treated skim milk (p ≥ 0.05) but the total color difference indicated better color retention with non-thermal preservation. The latter did not affect raw skim milk volatiles significantly after single or combined processing (p ≥ 0.05), but HTST caused considerable changes in their composition, including ketones, free fatty acids, hydrocarbons, and sulfur compounds (p < 0.05). The findings indicate that for the particular thermal and non-thermal treatments selected for this study, better retention of skim milk color and flavor components were obtained for the non-thermal treatments.

  5. Influence of physicochemical parameters and high pressure processing on the volatile compounds of Serrano dry-cured ham after prolonged refrigerated storage.

    PubMed

    Martínez-Onandi, N; Rivas-Cañedo, A; Picon, A; Nuñez, M

    2016-12-01

    One hundred and three volatile compounds were detected by solid-phase microextraction followed by gas chromatography-mass spectrometry in 30 ripened Serrano dry-cured hams, submitted or not to high pressure processing (HPP) and afterwards held for 5months at 4°C. The effect of ham physicochemical parameters and HPP (600MPa for 6min) on volatile compounds was assessed. Physicochemical parameters primarily affected the levels of acids, alcohols, alkanes, esters, benzene compounds, sulfur compounds and some miscellaneous compounds. Intramuscular fat content was the physicochemical parameter with the most pronounced effect on the volatile fraction of untreated Serrano ham after refrigerated storage, influencing the levels of 38 volatile compounds while aw, salt content and salt-in-lean ratio respectively influenced the levels of 4, 4 and 5 volatile compounds. HPP treatment affected 21 volatile compounds, resulting in higher levels of alkanes and ketones and lower levels of esters and secondary alcohols, what might affect Serrano ham odor and aroma after 5months of refrigerated storage.

  6. 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 ...

  7. 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 ...

  8. 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 ...

  9. Emission of volatile organic compounds from domestic coal stove with the actual alternation of flaming and smoldering combustion processes.

    PubMed

    Liu, Chengtang; Zhang, Chenglong; Mu, Yujing; Liu, Junfeng; Zhang, Yuanyuan

    2017-02-01

    Volatile organic compounds (VOCs) emissions from the chimney of a prevailing domestic stove fuelled with raw bituminous coal were measured under flaming and smoldering combustion processes in a farmer's house. The results indicated that the concentrations of VOCs quickly increased after the coal loading and achieved their peak values in a few minutes. The peak concentrations of the VOCs under the smoldering combustion process were significantly higher than those under the flaming combustion process. Alkanes accounted for the largest proportion (43.05%) under the smoldering combustion, followed by aromatics (28.86%), alkenes (21.91%), carbonyls (5.81%) and acetylene (0.37%). The emission factors of the total VOCs under the smoldering combustion processes (5402.9 ± 2031.8 mg kg(-1)) were nearly one order of magnitude greater than those under the flaming combustion processes (559.2 ± 385.9 mg kg(-1)). Based on the VOCs emission factors obtained in this study and the regional domestic coal consumption, the total VOCs emissions from domestic coal stoves was roughly estimated to be 1.25 × 10(8) kg a(-1) in the Beijing-Tianjin-Hebei region.

  10. 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.

  11. 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.

  12. Off-flavor related volatiles in soymilk as affected by soybean variety, grinding, and heat-processing methods.

    PubMed

    Zhang, Yan; Guo, Shuntang; Liu, Zhisheng; Chang, Sam K C

    2012-08-01

    Off-flavor of soymilk is a barrier to the acceptance of consumers. The objectionable soy odor can be reduced through inhibition of their formation or through removal after being formed. In this study, soymilk was prepared by three grinding methods (ambient, cold, and hot grinding) from two varieties (yellow Prosoy and a black soybean) before undergoing three heating processes: stove cooking, one-phase UHT (ultrahigh temperature), and two-phase UHT process using a Microthermics direct injection processor, which was equipped with a vacuuming step to remove injected water and volatiles. Eight typical soy odor compounds, generated from lipid oxidation, were extracted by a solid-phase microextraction method and analyzed by gas chromatography. The results showed that hot grinding and cold grinding significantly reduced off-flavor as compared with ambient grinding, and hot grinding achieved the best result. The UHT methods, especially the two-phase UHT method, were effective to reduce soy odor. Different odor compounds showed distinct concentration patterns because of different formation mechanisms. The two varieties behaved differently in odor formation during the soymilk-making process. Most odor compounds could be reduced to below the detection limit through a combination of hot grinding and two-phase UHT processing. However, hot grinding gave lower solid and protein recoveries in soymilk.

  13. Process-specific emission characteristics of volatile organic compounds (VOCs) from petrochemical facilities in the Yangtze River Delta, China.

    PubMed

    Mo, Ziwei; Shao, Min; Lu, Sihua; Qu, Hang; Zhou, Mengyi; Sun, Jin; Gou, Bin

    2015-11-15

    Process-specific emission characteristics of volatile organic compounds (VOCs) from petrochemical facilities were investigated in the Yangtze River Delta, China. Source samples were collected from various process units in the petrochemical, basic chemical, and chlorinated chemical plants, and were measured using gas chromatography-mass spectrometry/flame ionization detection. The results showed that propane (19.9%), propene (11.7%), ethane (9.5%) and i-butane (9.2%) were the most abundant species in the petrochemical plant, with propene at much higher levels than in petrochemical profiles measured in other regions. Styrene (15.3%), toluene (10.3%) and 1,3-butadiene (7.5%) were the major species in the basic chemical industry, while halocarbons, especially dichloromethane (15.2%) and chloromethane (7.5%), were substantial in the chlorinated chemical plant. Composite profiles were calculated using a weight-average approach based on the VOC emission strength of various process units. Emission profiles for an entire petrochemical-related industry were found to be process-oriented and should be established considering the differences in VOC emissions from various manufacturing facilities. The VOC source reactivity and carcinogenic risk potential of each process unit were also calculated in this study, suggesting that process operations mainly producing alkenes should be targeted for possible controls with respect to reducing the ozone formation potential, while process units emitting 1,3-butadiene should be under priority control in terms of toxicity. This provides a basis for further measurements of process-specific VOC emissions from the entire petrochemical industry. Meanwhile, more representative samples should be collected to reduce the large uncertainties.

  14. Development of a headspace-solid phase micro extraction method to monitor changes in volatile profile of rose (Rosa hybrida, cv David Austin) petals during processing.

    PubMed

    Bianchi, Giulia; Nuzzi, Monica; Avitabile Leva, Alexa; Rizzolo, Anna

    2007-05-25

    In the present study, headspace solid phase microextraction combined to capillary gas chromatography (HS-SPME-GC) has been applied for the determination of changes in the volatile profile of rose petals (Rosa hybrida, cvs David Austin) following processing (heat treatment and addition as an ingredient to a food product--for example yoghurt). Four SPME fibres at two sampling temperatures (40 and 60 degrees C) with a sampling time of 30 min were examined. Volatile profiles were detected either by FID or/and by olfactometry (ODP-II, Gerstel). Fibre testing was performed using raw rose petals for sampling temperature selection and an 18 characteristic rose volatile standard mixture in water was used to compare fibre performances at the sampling temperature of 60 degrees C. Polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibre at the sampling temperature of 60 degrees C was the most suitable to sample the rose alcohols phenyl ethanol, citronellol, nerol, geraniol and eugenol, as assessed by GC-olfactometry, not only from raw petals, but also from processed rose petals and the food product. PDMS-DVB fibre also showed a desired low affinity to volatiles from yoghurt, which reduces the influence of food matrix on the volatile profile. The method was linear over two orders of magnitude and had satisfactory repeatability, with limits of detection for the rose alcohols ranging from <1 to 10 ng/ml concentration levels.

  15. Slab-derived halogens and noble gases illuminate closed system processes controlling volatile element transport into the mantle wedge

    NASA Astrophysics Data System (ADS)

    Kobayashi, Masahiro; Sumino, Hirochika; Nagao, Keisuke; Ishimaru, Satoko; Arai, Shoji; Yoshikawa, Masako; Kawamoto, Tatsuhiko; Kumagai, Yoshitaka; Kobayashi, Tetsuo; Burgess, Ray; Ballentine, Chris J.

    2017-01-01

    Halogen and noble gas systematics are powerful tracers of volatile recycling in subduction zones. We present halogen and noble gas compositions of mantle peridotites containing H2O-rich fluid inclusions collected at volcanic fronts from two contrasting subduction zones (the Avacha volcano of Kamchatka arc and the Pinatubo volcano of Luzon arcs) and orogenic peridotites from a peridotite massif (the Horoman massif, Hokkaido, Japan) which represents an exhumed portion of the mantle wedge. The aims are to determine how volatiles are carried into the mantle wedge and how the subducted fluids modify halogen and noble gas compositions in the mantle. The halogen and noble gas signatures in the H2O-rich fluids are similar to those of marine sedimentary pore fluids and forearc and seafloor serpentinites. This suggests that marine pore fluids in deep-sea sediments are carried by serpentine and supplied to the mantle wedge, preserving their original halogen and noble gas compositions. We suggest that the sedimentary pore fluid-derived water is incorporated into serpentine through hydration in a closed system along faults at the outer rise of the oceanic, preserving Cl/H2O and 36Ar/H2O values of sedimentary pore fluids. Dehydration-hydration process within the oceanic lithospheric mantle maintains the closed system until the final stage of serpentine dehydration. The sedimentary pore fluid-like halogen and noble gas signatures in fluids released at the final stage of serpentine dehydration are preserved due to highly channelized flow, whereas the original Cl/H2O and 36Ar/H2O ratios are fractionated by the higher incompatibility of halogens and noble gases in hydrous minerals.

  16. 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.

  17. 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.

  18. Natural attenuation of volatile organic compounds (VOCs) in the leachate plume of a municipal landfill: Using alkylbenzenes as process probes

    USGS Publications Warehouse

    Eganhouse, R.P.; Cozzarelli, I.M.; Scholl, M.A.; Matthews, L.L.

    2001-01-01

    More than 70 individual VOCs were identified in the leachate plume of a closed municipal landfill. Concentrations were low when compared with data published for other landfills, and total VOCs accounted for less than 0.1% of the total dissolved organic carbon. The VOC concentrations in the core of the anoxic leachate plume are variable, but in all cases they were found to be near or below detection limits within 200 m of the landfall. In contrast to the VOCs, the distributions of chloride ion, a conservative tracer, and nonvolatile dissolved organic carbon, indicate little dilution over the same distance. Thus, natural attentuation processes are effectively limiting migration of the VOC plume. The distribution of C2-3-benzenes, paired on the basis of their octanol-water partition coefficients and Henry's law constants, were systematically evaluated to assess the relative importance of volatilization, sorption, and biodegradation as attenuation mechanisms. Based on our data, biodegradation appears to be the process primarily responsible for the observed attenuation of VOCs at this site. We believe that the alkylbenzenes are powerful process probes that can and should be exploited in studies of natural attenuation in contaminated ground water systems.

  19. Energy Transfer Collisional Process Involving Heteromolecular Collisions Between Methyl Fluoride and N_2, Ar, He, CO_2, and Air

    NASA Astrophysics Data System (ADS)

    Phillips, Dane J.; Everitt, Henry O.

    2013-06-01

    Time resolved IR/THz double resonance (DR) spectroscopy has been performed with a Q-switched CO_2 laser and heterodyne THz detection. The rate constants associated with allowed rotational- and vibrational-state changing collisions of CH_3F with N_2, Ar, He, CO_2, and air are measured by monitoring the temporal evolution of the absorption strength for numerous rotational transitions as a function of pressure. Collision partner dependent energy transfer processes are studied and compared with homomolecular collisions. Energy transfer maps and associated collisional cross sections will be presented for each collision partner.

  20. The abundance and relative volatility of refractory trace elements in Allende Ca,Al-rich inclusions - Implications for chemical and physical processes in the solar nebula

    NASA Technical Reports Server (NTRS)

    Kornacki, Alan S.; Fegley, Bruce, Jr.

    1986-01-01

    The relative volatilities of lithophile refractory trace elements (LRTE) were determined using calculated 50-percent condensation temperatures. Then, the refractory trace-element abundances were measured in about 100 Allende inclusions. The abundance patterns found in Allende Ca,Al-rich inclusions (CAIs) and ultrarefractory inclusions were used to empirically modify the calculated LRTE volatility sequence. In addition, the importance of crystal-chemical effects, diffusion constraints, and grain transport for the origin of the trace-element chemistry of Allende CAIs (which have important implications for chemical and physical processes in the solar nebula) is discussed.

  1. Scalable processes for fabricating non-volatile memory devices using self-assembled 2D arrays of gold nanoparticles as charge storage nodes.

    PubMed

    Muralidharan, Girish; Bhat, Navakanta; Santhanam, Venugopal

    2011-11-01

    We propose robust and scalable processes for the fabrication of floating gate devices using ordered arrays of 7 nm size gold nanoparticles as charge storage nodes. The proposed strategy can be readily adapted for fabricating next generation (sub-20 nm node) non-volatile memory devices.

  2. Human intracranial high-frequency activity during memory processing: neural oscillations or stochastic volatility?

    PubMed

    Burke, John F; Ramayya, Ashwin G; Kahana, Michael J

    2015-04-01

    Intracranial high-frequency activity (HFA), which refers to fast fluctuations in electrophysiological recordings, increases during memory processing. Two views have emerged to explain this effect: (1) HFA reflects a synchronous signal, related to underlying gamma oscillations, that plays a mechanistic role in human memory and (2) HFA reflects an asynchronous signal that is a non-specific marker of brain activation. We review recent data supporting each of these views and conclude that HFA during memory processing is more consistent with an asynchronous signal. Memory-related HFA is therefore best conceptualized as a biomarker of neural activation that can functionally map memory with high spatial and temporal precision.

  3. 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.

  4. 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.

  5. Effects of air injection during sap processing on maple syrup color, chemical composition and flavor volatiles.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Air injection (AI) is a maple sap processing technology reported to increase the efficiency of maple syrup production by increasing production of more economically valuable light-colored maple syrup, and reducing development of loose scale mineral precipitates in syrup, and scale deposits on evapora...

  6. 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.

  7. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, John R.; Dunn, Jerry G.; Avens, Larry R.

    1987-01-01

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF.sub.4 is not further oxidized to AmF.sub.6 by the application of O.sub.2 F at room temperature, while plutonium compounds present in the americium sample are fluorinated to volatile PuF.sub.6, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride.

  8. Uncoupled hydrogen and volatile fatty acids generation in a two-step biotechnological anaerobic process fed with actual site wastewater.

    PubMed

    Monti, Matilde; Scoma, Alberto; Martinez, Gonzalo; Bertin, Lorenzo; Fava, Fabio

    2015-05-25

    Among agro-wastes, olive mill wastewater (OMW) truly qualifies as a high impact organic residue due to its biochemical-rich composition and high annual production. In the present investigation, dephenolized OMW (OMWdeph) was employed as the feedstock for a biotechnological two-stage anaerobic process dedicated to the production of biohydrogen and volatile fatty acids (VFAs), respectively. To this end, two identically configured packed-bed biofilm reactors were operated sequentially. In the first, the hydraulic retention time was set to 1 day, whereas in the second it was equal to 5 days. The rationale was to decouple the hydrolysis of the organic macronutrients held by the OMWdeph, so as to quantitatively generate a biogas enriched in H2 (first stage aim), for the acidogenesis of the residual components left after hydrolysis, to then produce a highly concentrated mixture of VFAs (second stage aim). Results showed that the generation of H2 and VFAs was effectively split, with carbohydrates and lipids, respectively, being the main substrates of the two processes. About 250 ml H2 L(-1) day(-1) was produced, corresponding to a yield of 0.36 mol mol(-1) of consumed carbohydrates (expressed as glucose equivalents). The overall concentration of VFAs in the acidogenic process was 13.80 g COD L(-1), so that 2.76 g COD L(-1) day(-1) was obtained. Second generation biorefineries use a selected fraction of an organic waste to conduct a microbiologically-driven pathway towards the generation of one target molecule. With the proposed approach, a greater value of the waste was attained, since the multi-purpose two-stage process did not entail competition for substrates between the first and the second steps.

  9. Volatile N-nitrosamines in Meat Products: Potential Precursors, Influence of Processing and Mitigation Strategies.

    PubMed

    De Mey, Eveline; De Maere, Hannelore; Paelinck, Hubert; Fraeye, Ilse

    2015-11-03

    Meat products can be contaminated with carcinogenic N-nitrosamines, which is ascribed to the reaction between a nitrosating agent, originating from nitrite or smoke, and a secondary amine, derived from protein and lipid degradation. Although in model systems it is demonstrated that many amine containing compounds can be converted to N-nitrosamines, the yield is dependent of reaction conditions (e.g. low pH and high temperature). In this paper the influence of the composition of the meat products (e.g. pH, aw, spices) and processing (e.g. ageing, ripening, fermentation, smoking, heat treatment and storage) on the presence and availability of the amine precursors and the N-nitrosamine formation mechanism is discussed. In addition, this paper explores the current N-nitrosamine mitigation strategies in order to obtain healthier and more natural meat products.

  10. NEAR-REAL-TIME MEASUREMENT OF TRACE VOLATILE ORGANIC COMPOUNDS FROM COMBUSTION PROCESSES USING AN ON-LINE GAS CHROMATOGRAPH

    EPA Science Inventory

    The U.S. EPA's current regulatory approach for combustion and incineration sources emphasizes the use of real-time continuous emission monitors (CEMs) for particulate, Metals, and volatile, semivolatile, and of nonvolatile organic compounds to monitor source emissions. Currently...

  11. H2S and volatile fatty acids elimination by biofiltration: clean-up process for biogas potential use.

    PubMed

    Ramírez-Sáenz, D; Zarate-Segura, P B; Guerrero-Barajas, C; García-Peña, E I

    2009-04-30

    In the present work, the main objective was to evaluate a biofiltration system for removing hydrogen sulfide (H(2)S) and volatile fatty acids (VFAs) contained in a gaseous stream from an anaerobic digestor (AD). The elimination of these compounds allowed the potential use of biogas while maintaining the methane (CH(4)) content throughout the process. The biodegradation of H(2)S was determined in the lava rock biofilter under two different empty bed residence times (EBRT). Inlet loadings lower than 200 g/m(3)h at an EBRT of 81 s yielded a complete removal, attaining an elimination capacity (EC) of 142 g/m(3)h, whereas at an EBRT of 31 s, a critical EC of 200 g/m(3)h was reached and the EC obtained exhibited a maximum value of 232 g/m(3)h. For 1500 ppmv of H(2)S, 99% removal was maintained during 90 days and complete biodegradation of VFAs was observed. A recovery of 60% as sulfate was obtained due to the constant excess of O(2) concentration in the system. Acetic and propionic acids as a sole source of carbon were also evaluated in the bioreactor at different inlet loadings (0-120 g/m(3)h) obtaining a complete removal (99%) for both. Microcosms biodegradation experiments conducted with VFAs demonstrated that acetic acid provided the highest biodegradation rate.

  12. 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

  13. 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)

  14. Influence of enamel matrix derivative (Emdogain) and sodium fluoride on the healing process in delayed tooth replantation: histologic and histometric analysis in rats.

    PubMed

    Poi, Wilson Roberto; Carvalho, Roberta Martinelli; Panzarini, Sônia Regina; Sonoda, Celso Koogi; Manfrin, Thais Mara; Rodrigues, Thais da Silveira

    2007-02-01

    Although it has already been shown that enamel matrix derivative (Emdogain) promotes periodontal regeneration in the treatment of intrabony periodontal defects, there is little information concerning its regenerative capacity in cases of delayed tooth replantation. To evaluate the alterations in the periodontal healing of replanted teeth after use of Emdogain, the central incisors of 24 Wistar rats (Rattus norvegicus albinus) were extracted and left on the bench for 6 h. Thereafter, the dental papilla and the enamel organ of each tooth were sectioned for pulp removal by a retrograde way and the canal was irrigated with 1% sodium hypochlorite. The teeth were assigned to two groups: in group I, root surface was treated with 1% sodium hypochlorite for 10 min (changing the solution every 5 min), rinsed with saline for 10 min and immersed in 2% acidulated-phosphate sodium fluoride for 10 min; in group II, root surfaces were treated in the same way as described above, except for the application of Emdogain instead of sodium fluoride. The teeth were filled with calcium hydroxide (in group II right before Emdogain was applied) and replanted. All animals received antibiotic therapy. The rats were killed by anesthetic overdose 10 and 60 days after replantation. The pieces containing the replanted teeth were removed, fixated, decalcified and paraffin-embedded. Semi-serial 6-microm-thick sections were obtained and stained with hematoxylin and eosin for histologic and histometric analyses. The use of 2% acidulated-phosphate sodium fluoride provided more areas of replacement resorption. The use of Emdogain resulted in more areas of ankylosis and was therefore not able to avoid dentoalveolar ankylosis. It may be concluded that neither 2% acidulated-phosphate sodium fluoride nor Emdogain were able to prevent root resorption in delayed tooth replantation in rats.

  15. 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.

  16. Pesticide Volatilization

    EPA Pesticide Factsheets

    We consider the risks posed when pesticides volatilize during or after application. The movement of vapors through the air is not the same as pesticide movement by spray drift, erosion, or windblown soil particles.

  17. Phase A design study of microgravity fluoride fiber puller

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Smith, Guy A.; Kosten, Susan

    1994-01-01

    Improved transmission properties for fluoride fibers due to space processing has great potential for commercial benefits. Phase A design study will determine conceptual feasibility and provide initial definition of the technical requirements and design issues for space.

  18. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, R.B.

    1987-05-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  19. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, Raoul B.

    1988-01-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  20. In-cloud processes of methacrolein under simulated conditions - Part 3: Hygroscopic and volatility properties of the formed secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Michaud, V.; El Haddad, I.; Liu, Yao; Sellegri, K.; Laj, P.; Villani, P.; Picard, D.; Marchand, N.; Monod, A.

    2009-07-01

    The hygroscopic and volatility properties of secondary organic aerosol (SOA) produced from the nebulization of solutions after aqueous phase photooxidation of methacrolein was experimentally studied in a laboratory, using a Volatility-Hygroscopicity Tandem DMA (VHTDMA). The obtained SOA were 80% 100°C-volatile after 5 h of reaction and only 20% 100°C-volatile after 22 h of reaction. The Hygroscopic Growth Factor (HGF) of the SOA produced from the nebulization of solutions after aqueous-phase photooxidation of methacrolein is 1.34-1.43, which is significantly higher than the HGF of SOA formed by gas-phase photooxidation of terpenes, usually found almost hydrophobic. These hygroscopic properties were confirmed for SOA formed by the nebulization of the same solutions where NaCl was added. The hygroscopic properties of the cloud droplet residuals decrease with the reaction time, in parallel with the formation of more refractory compounds. This decrease was mainly attributed to the 250°C-refractive fraction (presumably representative of the highest molecular weight compounds), which evolved from moderately hygroscopic (HGF of 1.52) to less hygroscopic (HGF of 1.36). Oligomerization is suggested as a process responsible for the decrease of both volatility and hygroscopicity with time. The NaCl seeded experiments enabled us to show that 19±4 mg L-1 of SOA was produced after 9.5 h of reaction and 41±9 mg L-1 after 22 h of in-cloud reaction. Because more and more SOA is formed as the reaction time increases, our results show that the reaction products formed during the aqueous-phase OH-oxidation of methacrolein may play a major role in the properties of residual particles upon the droplet's evaporation. Therefore, the specific physical properties of SOA produced during cloud processes should be taken into account for a global estimation of SOA and their atmospheric impacts.

  1. In-cloud processes of methacrolein under simulated conditions - Part 3: Hygroscopic and volatility properties of the formed Secondary Organic Aerosol

    NASA Astrophysics Data System (ADS)

    Michaud, V.; El Haddad, I.; Liu, Y.; Sellegri, K.; Laj, P.; Villani, P.; Picard, D.; Marchand, N.; Monod, A.

    2009-03-01

    The hygroscopic and volatility properties of SOA produced from the nebulization of solutions after aqueous phase photooxidation of methacrolein was experimentally studied in laboratory, using a Volatility-Hygroscopicity Tandem DMA (VHTDMA). The obtained SOA were 80% 100°C-volatile after 5 h of reaction and only 20% 100°C-volatile after 22 h of reaction. The Hygroscopic Growth Factor (HGF) of the SOA produced from the nebulization of solutions after aqueous-phase photooxidation of methacrolein is 1.34-1.43, which is significantly higher than the HGF of SOA formed by gas-phase phtooxidation of terpenes, usually found nearly hydrophobic. These hygroscopic properties were confirmed for SOA formed by the nebulization of the same solutions where NaCl was added. The hygroscopic properties of the cloud droplet residuals decrease with the reaction time, in parallel with the formation of more refractory compounds. This decrease was mainly attributed to the 250°C-refractive fraction (presumably representative of the highest molecular weigh compounds), evolved from moderately hygroscopic (HGF of 1.52) to less hygroscopic (HGF of 1.36). Oligomerization is suggested as a process responsible for the decrease of both volatility and hygroscopicity with time. The NaCl seeded experiments enabled us to show that 19±4 mg L-1 of SOA was produced after 9.5 h of reaction and 41±9 mg L-1 after 22 h of in-cloud reaction. Because more and more SOA is formed as the reaction time increases, our results show that the reaction products formed during the aqueous-phase OH-oxidation of methacrolein may play a major role in the properties of residual particles upon droplet's evaporation. Therefore, the specific physical properties of SOA produced during cloud processes should be taken into account for a global estimation of SOA and their atmospheric impacts.

  2. Fluorination process using catalyst

    DOEpatents

    Hochel, Robert C.; Saturday, Kathy A.

    1985-01-01

    A process for converting an actinide compound selected from the group consisting of uranium oxides, plutonium oxides, uranium tetrafluorides, plutonium tetrafluorides and mixtures of said oxides and tetrafluorides, to the corresponding volatile actinide hexafluoride by fluorination with a stoichiometric excess of fluorine gas. The improvement involves conducting the fluorination of the plutonium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF.sub.3, AgF.sub.2 and NiF.sub.2, whereby the fluorination is significantly enhanced. The improvement also involves conducting the fluorination of one of the uranium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF.sub.3 and AgF.sub.2, whereby the fluorination is significantly enhanced.

  3. Fluorination process using catalysts

    DOEpatents

    Hochel, R.C.; Saturday, K.A.

    1983-08-25

    A process is given for converting an actinide compound selected from the group consisting of uranium oxides, plutonium oxides, uranium tetrafluorides, plutonium tetrafluorides and mixtures of said oxides and tetrafluorides, to the corresponding volatile actinide hexafluoride by fluorination with a stoichiometric excess of fluorine gas. The improvement involves conducting the fluorination of the plutonium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF/sub 3/, AgF/sub 2/ and NiF/sub 2/, whereby the fluorination is significantly enhanced. The improvement also involves conducting the fluorination of one of the uranium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF/sub 3/ and AgF/sub 2/, whereby the fluorination is significantly enhanced.

  4. 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)

  5. On the volatility of volatility

    NASA Astrophysics Data System (ADS)

    Hsu, Stephen D. H.; Murray, Brian M.

    2007-07-01

    The Chicago Board Options Exchange (CBOE) Volatility Index, VIX, is calculated based on prices of out-of-the-money put and call options on the S&P 500 index (SPX). Sometimes called the “investor fear gauge”, the VIX is a measure of the implied volatility of the SPX, and is observed to be correlated with the 30-day realized volatility of the SPX. Changes in the VIX are observed to be negatively correlated with changes in the SPX. However, no significant correlation between changes in the VIX and changes in the 30-day realized volatility of the SPX are observed. We investigate whether this indicates a mispricing of options following large VIX moves, and examine the relation to excess returns from variance swaps. The sense in which the term “mispricing” is used is discussed in the paper.

  6. Relationship of fluoride in drinking water to other drinking water parameters

    SciTech Connect

    Lynch, C.F.

    1987-01-01

    Fluoride in drinking water and 32 other drinking water variables were evaluated in an epidemiologic study of 158 municipalities in the State of Iowa. The study included three study groups: two for controlled fluoridation and one for natural fluoride. Previous epidemiologic studies of fluoride in drinking water have rarely addressed other drinking water parameters. The results indicated that controlled fluoridation municipalities were more likely to have initiated other treatment practices such as chlorination. Natural fluoride drinking water concentrations were positively correlated with water source depth, and thereby related to other depth-associated variables such as radium 226, strontium, and nitrogen. Future epidemiologic studies evaluating the safety of fluoride in drinking water should address the potential for confounding by other water variables and treatment processes.

  7. Assessment of water contribution on total fluoride intake of various age groups of people in fluoride endemic and non-endemic areas of Dindigul District, Tamil Nadu, South India.

    PubMed

    Viswanathan, Gopalan; Gopalakrishnan, S; Siva Ilango, S

    2010-12-01

    The prevalence of fluorosis is mainly due to the intake of large quantities of fluoride through water. It is necessary to determine the contribution of water used for drinking and food processing and other diet sources on daily fluoride intake for finding the ways to reduce the excess fluoride intake than the minimum safe level intake of 0.05 mg/kg/day. The main objectives of this study are to determine the quantitative impact of water through drinking and cooking of food and beverages on total fluoride intake as well as to estimate the contribution of commonly consumed diet sources on total fluoride intake. Contribution of water on daily fluoride intake and estimation of total fluoride intake through the diet sources were accomplished through analysis of fluoride in drinking water, solid and liquid food items, Infant formulae, tea and coffee infusions using fluoride ion selective electrode. Determination of incidence of fluorosis in different fluoride endemic areas in Dindigul District of Tamil Nadu, South India is achieved through clinical survey. The percentage of daily fluoride intake through water is significantly higher for infants than children, adults and old age groups of people. The percentile scores of fluoride intake through water from drinking and cooking increases with increase of water fluoride level. The rate of prevalence of fluorosis is higher in adolescent girls and females than adolescent boys and males residing in high fluoride endemic areas. More than 60% of the total fluoride intake per day derived from water used for drinking and food processing. Hence the people residing in the fluoride endemic areas in Dindigul District of Tamil Nadu, South India are advised to take serious concern about the fluoride level of water used for drinking and cooking to avoid further fluorosis risks.

  8. 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.

  9. Novel approach for the determination of volatile compounds in processed onion by headspace gas chromatography-mass spectrometry (HS GC-MS).

    PubMed

    Colina-Coca, Clara; González-Peña, Diana; Vega, Estela; de Ancos, Begoña; Sánchez-Moreno, Concepción

    2013-01-15

    A novel headspace gas chromatography-mass spectrometry (HS GC-MS) method was developed for analysis of volatile compounds in onion (Allium cepa L. var. cepa, 'Recas'). MS was operated using full scan mode and selective ion monitoring (SIM) mode in order to quantify some specific compounds with increased sensitivity relative to full scan mode. The limits of detection and quantitation ranged from 0.01 to 0.10 μg/g and from 0.02 to 3.83 μg/g fresh weight, respectively, for studied compounds. The procedure allowed the identification of eighteen compounds and quantitation of nine compounds in the volatile fraction of onion, belonging mainly to di-, and trisulfides and aldehydes. These methods were applied to evaluate how high-pressure (HP) as a processing technology affects onion volatile compounds, responsible in part of the onion biological activity. Onion samples were treated at T1: 200 MPa/25°C/5 min, T2: 400 MPa/25°C/5 min and T3: 600 MPa/25°C/5 min (treatments). In addition, the difference among diced, freeze-dried and pulverized onions (groups) was studied, in order to select the process more adequate for better preserving volatile compounds. The results obtained in full scan mode showed that both main factors (group and treatment) had a significant effect (P<0.001). There were also significant differences between groups and treatments for all compounds, being the main effect of group more marked by HS GC-MS using selective ion monitoring (SIM) mode. For 2-methyl 2-pentenal, dimethyl trisulfide, and methyl propyl trisulfide it has been observed an increase in freeze-dried and pulverized onion samples compared with diced samples regardless the HP treatment. However, freeze-drying and pulverization processes affected the stability of propionaldehyde, 1-propanethiol, hexanal, dipropyl disulfide, and dipropyl trisulfide, diminishing their content regardless the HP treatment. HP at 200 and 400 MPa/25°C/5 min were the least detrimental treatments to the total

  10. 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.

  11. The history of public health use of fluorides in caries prevention

    PubMed Central

    Šket, Tea; Kukec, Andreja; Kosem, Rok

    2017-01-01

    Abstract Aim The aim of our study was to chronologically analyse various public health measures of fluoride use in caries prevention. Methods We systematically searched the PubMed database on the preventive role of fluorides in public health, published from 1984 to 2014. The search process was divided into four steps, where inclusion and exclusion criteria were defined. Qualitative methodology was used for the article analysis. In the research process, the described forms of F use, diversity of the described F agents, and the observed population group were analysed. Results In our systematic review, 40 relevant reviews were revealed. Fluorides have been used in many different forms, but only a few studies showed their significant role in public health. Water fluoridation was the most important public health measure. In the recent decades, the number of studies on topical fluorides is constantly rising. The most extensively described topical forms of fluorides are professionally applied fluoride agents and fluoride toothpaste for home-use. The use of fluoride containing toothpaste in caries prevention is a safe and successful public health measure (PHM) if their use is widespread, and it is recommended for all. The results on other topical forms of fluorides are insufficient to be suggested as an important PHM. Conclusions The role of fluorides in public health prevention has changed in accordance with the knowledge about the fluoride cariostatic mechanism. Previously the most important pre-eruptive effect of fluorides was supplemented by the post eruptive effect. Abundant evidence exists to show the effectiveness of systemic and topical fluorides. PMID:28289474

  12. [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.

  13. The evolution of immiscible silicate and fluoride melts: Implications for REE ore-genesis

    NASA Astrophysics Data System (ADS)

    Vasyukova, O.; Williams-Jones, A. E.

    2016-01-01

    The Mid-Proterozoic peralkaline Strange Lake pluton (Québec-Labrador, Canada) exhibits extreme enrichment in high field strength elements (HFSE), including the rare earth elements (REE), particularly in pegmatites. On the basis of a study of melt inclusions, we proposed recently that fluoride-silicate melt immiscibility played an important and perhaps dominant role in concentrating the REE within the pluton. Here we present further evidence for silicate-fluoride immiscibility at Strange Lake from a sample of the hypersolvus granite, which contains an inclusion composed largely of REE and HFSE minerals. The inclusion (∼5 cm in diameter) comprises a narrow rim containing chevkinite-(Ce) and zircon in a fluorite matrix, a core of fluorbritholite-(Ce) and bastnäsite-(Ce) and a transition zone between the rim and the core consisting of a fine-grained intergrowth of bastnäsite-(Ce), gagarinite-(Y) and fluorite. We propose that the inclusion formed as a result of silicate-fluoride immiscibility, which occurred early in the emplacement history of the Strange Lake pluton, and that it represents the fluoride melt. After separation of the two melts, the boundary between them acted as a locus of crystallisation, where crystals formed repeatedly due to heterogeneous (surface catalysed) nucleation. Zircon crystallised shortly after melt phase separation, and was followed by the growth of perthite together with arfvedsonite and quartz. As a result, the silicate melt surrounding the fluoride inclusion became enriched in volatiles that facilitated crystallisation of progressively larger crystals in the inclusion; large crystals of arfvedsonite and perthite were succeeded by even larger crystals of quartz. Massive crystallisation of chevkinite-(Ce) followed, forming the rim of the inclusion. The fluoride melt, which constituted the matrix to the silicate minerals and chevkinite-(Ce), crystallised after chevkinite-(Ce), forming fluorbritholite-(Ce) and fluorite. Aqueous fluid

  14. Flash Thermal Conditioning of Olive Pastes during the Oil Mechanical Extraction Process: Cultivar Impact on the Phenolic and Volatile Composition of Virgin Olive Oil.

    PubMed

    Veneziani, Gianluca; Esposto, Sonia; Taticchi, Agnese; Selvaggini, Roberto; Urbani, Stefania; Di Maio, Ilona; Sordini, Beatrice; Servili, Maurizio

    2015-07-08

    The concentration of phenolic and volatile compounds in virgin olive oil (VOO) is closely related to the different operative conditions applied to the mechanical extraction process of the olive oil. However, the great qualitative and quantitative variability of these compounds indicates an important role played by genetic and agronomic aspects. A heat exchanger was placed in front of a traditional, covered malaxer to study the impact of flash thermal conditioning (FTC) of olive paste on the quality of VOO, which is highly influenced by phenolic release and aroma generation. The VOO flash thermal conditioning of five major Italian cultivars showed a higher concentration of phenols (range of increase percentage, 9.9-37.3%) compared to the control trials, whereas the FTC treatment featured a differentiated impact on the volatile fractions, associated with the genetic origins of the olives.

  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. Current concepts on the theories of the mechanism of action of fluoride.

    PubMed

    ten Cate, J M

    1999-12-01

    The caries-preventive effect of fluoride is mainly attributed to the effects on demineralization/remineralization at the tooth oral fluids interface. Sub ppm levels of fluoride in saliva are effective in shifting the balance from demineralization, leading to caries, to remineralization. This is attributed to the fluoride-enhanced precipitation of calcium phosphates, and the formation of fluorhydroxyapatite in the dental tissues. Low fluoride levels are found in saliva after toothbrushing with fluoride containing dentifrices. Similar concentrations are ineffective in interfering with processes of growth and metabolism of bacteria, and also do not result in a significantly reduced dissolution of tooth mineral as a result of (firmly bound) fluoride incorporation. Comparative studies of fluoride efficacy have shown that higher concentrations in solution are needed in pH-cycling studies of dentine than in enamel to maintain the mineral balance or to induce remineralization. This is attributed to the greater solubility of the dentine and the smaller size of the dentine crystallites compared to enamel. Fluoride slow-release devices, in the form of fluoride-releasing restorative materials, may serve to increase the fluoride levels in saliva and plaque to levels at which caries can be prevented, also in high-risk patients. Research questions for the next millennium and future perspectives for fluoride applications should be found in the retention and slow release of fluoride after various combinations of fluoride treatment, the combination of fluoride and anti-microbial treatment, the individualization of caries prevention, and the combination of preventive schemes with new developments in caries diagnosis.

  17. 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.

  18. Performance of novel hydroxyapatite nanowires in treatment of fluoride contaminated water.

    PubMed

    He, Junyong; Zhang, Kaisheng; Wu, Shibiao; Cai, Xingguo; Chen, Kai; Li, Yulian; Sun, Bai; Jia, Yong; Meng, Fanli; Jin, Zhen; Kong, Lingtao; Liu, Jinhuai

    2016-02-13

    Novel ultralong hydroxyapatite (HAP) nanowires were successfully prepared for fluoride removal for the first time. The fluoride adsorption on the HAP nanowires was studied on a batch mode. The results revealed that the adsorption data could be well described by the Freundlich model, and the adsorption kinetic followed the pseudo-second-order model. The maximum of adsorption capacity was 40.65 mg/g at pH 7.0 when the fluoride concentration is 200mg/L. The thermodynamic parameters suggested that the adsorption of fluoride was a spontaneous endothermic process. The FT-IR, XPS and Zeta potential analysis revealed that both anion exchange and electrostatic interactions were involved in the adsorption of fluoride. Furthermore, the HAP nanowires were made into HAP membrane through a simple process of suction filtration. Membrane filtration experiments revealed that the fluoride removal capabilities depended on the membrane thickness, flow rate and initial concentration of fluoride. The as-prepared membrane could remove fluoride efficiently through continues filtration. The filtered water amount could reach 350, 192, and 64 L/m(2) when the fluoride concentrations were 4, 5 and 8 ppm, respectively, using the HAP membrane with only 150 μm thickness. The as-synthesized ultralong HAP nanowires were thus demonstrated to be very effective and biocompatible adsorbents for fluoride removal from contaminated water.

  19. Changes in headspace volatile concentrations of coffee brews caused by the roasting process and the brewing procedure.

    PubMed

    López-Galilea, Isabel; Fournier, Nicole; Cid, Concepción; Guichard, Elisabeth

    2006-11-01

    Headspace-solid-phase microextraction technique (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to characterize the aroma compounds of coffee brews from commercial conventional and torrefacto roasted coffee prepared by filter coffeemaker and espresso machine. A total of 47 volatile compounds were identified and quantified. Principal component analysis (PCA) was applied to differentiate coffee brew samples by volatile compounds. Conventional and torrefacto roasted coffee brews were separated successfully by principal component 1 (68.5% of variance), and filter and espresso ones were separated by principal component 2 (19.5% of variance). By GC olfactometry, a total of 34 aroma compounds have been perceived at least in half of the coffee extracts and among them 28 were identified, among which octanal was identified for the first time as a contributor to coffee brew aroma.

  20. 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.

  1. 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.

  2. PROCESS FOR CONTINUOUSLY SEPARATING IRRADIATION PRODUCTS OF THORIUM

    DOEpatents

    Hatch, L.P.; Miles, F.T.; Sheehan, T.V.; Wiswall, R.H.; Heus, R.J.

    1959-07-01

    A method is presented for separating uranium-233 and protactinium from thorium-232 containing compositions which comprises irradiating finely divided particles of said thorium with a neutron flux to form uranium-233 and protactinium, heating the neutron-irradiated composition in a fluorine and hydrogen atmosphere to form volatile fluorides of uranium and protactinium and thereafter separating said volatile fluorides from the thorium.

  3. [Fluoride effect on bone formation--an overview].

    PubMed

    Mohr, H

    1990-12-01

    The purpose of this review is to evaluate our present knowledge of fluoride effect on bone formation on basis of the literature. It is likely that fluoride affects the remodelling processes of the skeleton as well as growth related bone formation. During bone remodelling the amount of bone and osteoid tissue is increased by alteration of the balance between resorption and formation. This finding may be accompagnied by impaired mineralization. In studies of fluoride effect on growth related bone formation a number of quantitative histologic alterations have been observed. These include reduction in epiphyseal plate thickness and changes in cellular morphology as well as a retardation of mineralization. The pathogenetic mechanisms behind the observed effects and the variation in tissue response are still unexplained. Fluoride may have a direct cellular effect causing disturbances in cell morphology and metabolism, but the effects may also involve local supracellular mechanisms as well as the general homeostasis of the individual.

  4. Critical factors determining fluoride concentration in tea leaves produced from Anhui province, China.

    PubMed

    Cai, Huimei; Zhu, Xiaohui; Peng, Chuanyi; Xu, Wei; Li, Daxiang; Wang, Yijun; Fang, Shihui; Li, Yeyun; Hu, Shaode; Wan, Xiaochun

    2016-09-01

    This study investigated the fluoride present in tea plants (Camellia sinensis (L.) O. Kuntze) and its relationship to soils, varieties, seasons and tea leaf maturity. The study also explored how different manufacturing processes affect the leaching of fluoride into tea beverages. The fluoride concentration in the tea leaves was significantly correlate to the concentration of water-soluble fluoride in the soil. Different tea varieties accumulated different levels of fluoride, with varieties, Anji baicha having the highest and Nongkang zao having the lowest fluoride concentration. In eight different varieties of tea plant harvested over three tea seasons, fluoride concentration were highest in the summer and lowest in the spring in china. The fluoride concentration in tea leaves was directly related to the maturity of the tea leaves at harvest. Importantly, the tea manufacturing process did not introduced fluoride contamination. The leaching of fluoride was 6.8% and 14.1% higher in black and white tea, respectively, than in fresh tea leaves. The manufacturing step most affecting the leaching of fluoride into tea beverage was withering used in white, black and oolong tea rather than rolling or fermentation. The exposure and associated health risks for fluoride concentration in infusions of 115 commercially available teas from Chinese tea markets was determined. The fluoride concentration ranged from 5.0 to 306.0mgkg(-1), with an average of 81.7mgkg(-1). The hazard quotient (HQ) of these teas indicated that there was no risk of fluorosis from drinking tea, based on statistical analysis by Monte Carlo simulation.

  5. 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.

  6. Some Unusual Rheological Responses of Poly(Vinylidene Fluoride-Co-Hexafluoropropylene) Solutions in Dimethyl Acetamide and Their Effects on the Electrospinning Process

    NASA Astrophysics Data System (ADS)

    Seo, Jae Sik; Lee, Ki Hyun; Kim, Byoung Chul

    2008-07-01

    The rheological properties of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in dimethyl acetamide (DMAc) were investigated to obtain preliminary data for electrospinning. Intrinsic viscosity data suggested that solubility of PVDF-HFP was reduced with increasing temperature. Over the temperature range of 30 to 70 °C, the dynamic viscosity of the concentrated solutions was increased with increasing temperature and Bingham behavior became more noticed. In addition, increase of temperature and concentration of the solutions increased yield stress and relaxation time. Although the dynamic viscosity was increased with increasing temperature, electrospinning temperature had little effects on the resultant fiber morphology on the condition that other spinning conditions were identical.

  7. Estimating the importance of multi-phase processing on secondary organic aerosol based on a functional-group resolving volatility basis set approach

    NASA Astrophysics Data System (ADS)

    Knote, C. J.; Hodzic, A.; Aumont, B.; Madronich, S.

    2014-12-01

    Traditional understanding views secondary organic aerosol (SOA) formation in the atmosphere as continuous gas-phase oxidation of precursors such as isoprene, aromatics or alkanes. Recent research found that these oxidation products are also highly water soluble. It is further understood that the liquid-phase of cloud droplets as well as deliquesced particles could mediate SOA formation through chemistry in the aqueous-phase. While the effect of multi-phase processing has been studied in detailed for specific compounds like glyoxal or methylglyoxal, an integrated approach that considers the large number of individual compounds has been missing due to the complexity involved. In our work we explore the effects of multi-phase processing on secondary organic aerosol from an explicit modeling perspective.Volatility and solubility determine in which phase a given molecule will be found under given atmospheric conditions. Volatility has already been used to simplify the description of SOA formation in the gas-phase in what became known as the Volatility Basis Set approach (VBS). Compounds contributing to SOA formation are grouped by volatility and then treated as a whole. A number of studies extended the VBS by adding a second dimension like oxygen to carbon ratio or the mean oxidation state. In our work we use functional groups as second dimension.Using explicit oxidation chemistry modeling (GECKO-A) we derive SOA yields as well as their composition in terms of functional groups for commonly used precursors. We then investigate the effect of simply partitioning functional-group specific organic mass into cloud droplets and deliquesced aerosol based on their estimated solubility. Finally we apply simple chemistry in the aqueous-phase and relate changes in functional groups to changes in volatility and subsequent changes in partitioning between gas- and aerosol-phase.In our presentation we will explore the sensitivites of the multi-phase system in a box model setting with

  8. Evolution of Triton's volatile budget

    NASA Technical Reports Server (NTRS)

    Lunine, J. I.

    1993-01-01

    Triton's volatile budget provides important links to planetary formation processes in the cold outer solar nebula. However, the budget has been modified by processes subsequent to the accretion of this body. It is of interest to assess whether certain formation environments can be ruled out for Triton on the basis of its current volatile abundances, and also to quantify some of the post-accretional processes by which the abundances have been modified.

  9. 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.

  10. 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.

  11. 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…

  12. Mass Wasting and Ground Collapse in Terrains of Volatile-Rich Deposits as a Solar System-Wide Geological Process: The Pre-Galileo View

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Mellon, Michael T.; Zent, Aaron P.

    1996-01-01

    The polar terrains of Mars are covered in many places with irregular pits and retreating scarps, as are some of the surfaces of the outer-planet satellites. These features are interpreted by us as diagnostic of exogenic degradation due to the loss of a volatile rock-forming matrix or cement. In this study we propose that sublimation degradation is a plausible Solar Systemwide geological process. Candidate examples have been identified on Mars, Io, and Triton, and possibly Europa and Ganymede. We envision this process as having two end-member expressions (pits and scarps), for which we hypothesize two end-member mechanisms (massive localized lenses and areally extensive basal layers). In this study we focus on the role this process may play on the surfaces of the galilean satellites. Our principle modeling results are that for these satellites, H2S, CO2, and NH3 are the only viable candidate volatiles for sublimation degradation of landforms, in light of galilean satellite cosmochemistry. For Io's polar regions only H2S, and then only from slopes that face the Sun and have thin lags, is volatile enough to cause the observed sublimation-induced erosion at those latitudes. SO2 is not a viable candidate as an agent of erosion, especially for these polar landforms. In the case of Europa, only CO2 and H2S are viable candidates (given surface age constraints). Both species could be efficient eroders in nonpolar regions. H2S could generate erosion within the polar regions if the deposition and erosion conditions were essentially identical as those we invoked for Io's polar regions. For Ganymede (and Callisto) NH3 might be an agent of erosion in equatorial terrains of great age. The sublimation of CO2 and H2S is much more robust than NH3. The much slower rate of sublimation degradation from NH3 might be detectable by Galileo and used as a compositional indicator.

  13. 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

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. Effect of water fluoridation on the development of medial vascular calcification in uremic rats.

    PubMed

    Martín-Pardillos, Ana; Sosa, Cecilia; Millán, Ángel; Sorribas, Víctor

    2014-04-06

    Public water fluoridation is a common policy for improving dental health. Fluoride replaces the hydroxyls of hydroxyapatite, thereby improving the strength of tooth enamel, but this process can also occur in other active calcifications. This paper studies the effects of water fluoridation during the course of vascular calcification in renal disease. The effect of fluoride was studied in vitro and in vivo. Rat aortic smooth muscle cells were calcified with 2mM Pi for 5 days. Fluoride concentrations of 5-10 μM--similar to those found in people who drink fluoridated water--partially prevented calcification, death, and osteogene expression in vitro. The anticalcifying mechanism was independent of cell activity, matrix Gla protein, and fetuin A expressions, and it exhibited an IC50 of 8.7 μM fluoride. In vivo, however, fluoridation of drinking water at 1.5mg/L (concentration recommended by the WHO) and 15 mg/L dramatically increased the incipient aortic calcification observed in rats with experimental chronic kidney disease (CKD, 5/6-nephrectomy), fed a Pi-rich fodder (1.2% Pi). Fluoride further declined the remaining renal function of the CKD animals, an effect that most likely overwhelmed the positive effect of fluoride on calcification in vitro. Ultrastructural analysis revealed that fluoride did not modify the Ca/P atomic ratio, but it was incorporated into the lattice of in vivo deposits. Fluoride also converted the crystallization pattern from plate to rode-like structures. In conclusion, while fluoride prevents calcification in vitro, the WHO's recommended concentrations in drinking water become nephrotoxic to CKD rats, thereby aggravating renal disease and making media vascular calcification significant.

  20. 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.

  1. [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.

  2. 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.

  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. Grout formulation for disposal of low-level and hazardous waste streams containing fluoride

    DOEpatents

    McDaniel, E.W.; Sams, T.L.; Tallent, O.K.

    1987-06-02

    A composition and related process for disposal of hazardous waste streams containing fluoride in cement-based materials is disclosed. the presence of fluoride in cement-based materials is disclosed. The presence of fluoride in waste materials acts as a set retarder and as a result, prevents cement-based grouts from setting. This problem is overcome by the present invention wherein calcium hydroxide is incorporated into the dry-solid portion of the grout mix. The calcium hydroxide renders the fluoride insoluble, allowing the grout to set up and immobilize all hazardous constituents of concern. 4 tabs.

  6. VOLATILIZATION OF ALKYLBENZENES FROM WATER.

    USGS Publications Warehouse

    Rathbun, R.E.; Tai, D.Y.

    1985-01-01

    Volatilization is a physical process of importance in determining the fate of many organic compounds in streams and rivers. This process is frequently described by the conceptual-two-film model. The model assumes uniformly mixed water and air phases separated by thin films of water and air in which mass transfer is by molecular diffusion. Mass-transfer coefficients for the water and air films are related to an overall mass-transfer coefficient for volatilization through the Henry's law constant.

  7. 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.

  8. 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.

  9. 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)

  10. Capture and identification of the volatile components in crude and processed herbal medicines through on-line purge and trap technique coupled with GC × GC-TOF MS.

    PubMed

    Cao, Gang; Xu, Zhiwei; Wu, Xin; Li, Qingli; Chen, Xiaocheng

    2014-01-01

    This work aimed to investigate the volatile components in crude and processed herbal medicines (HMs). Using Atractylodis Macrocephalae Rhizoma (AMR) as a model HM, the volatile components were captured through on-line purge and trap technique and identified by using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF MS) system. A total of 224 and 171 volatile compounds were identified in crude and processed AMR samples, respectively. After frying with honey-bran, 52 compounds which were found in crude AMR samples disappeared in processed AMR samples, and 15 compounds were newly generated in processed AMR. The established method can be applied in different research areas such as HM and food processing.

  11. The interaction of zinc oxide-based dental cements with aqueous solutions of potassium fluoride.

    PubMed

    Pawluk, K; Booth, S E; Coleman, N J; Nicholson, J W

    2008-09-01

    The ability of zinc oxide-based dental cements (zinc phosphate and zinc polycarboxylate) to take up fluoride from aqueous solution has been studied. Only zinc phosphate cement was found to take up any measurable fluoride after 5 h exposure to the solutions. The zinc oxide filler of the zinc phosphate also failed to take up fluoride from solution. The key interaction for this uptake was thus shown to involve the phosphate groups of the set cement. However, whether this took the form of phosphate/fluoride exchange, or the formation of oxyfluoro-phosphate groups was not clear. Fluoride uptake followed radicaltime kinetics for about 2 h in some cases, but was generally better modelled by the Elovich equation, dq(t)/dt = alpha exp(-betaq(t)). Values for alpha varied from 3.80 to 2.48 x 10(4), and for beta from 7.19 x 10(-3) to 0.1946, though only beta showed any sort of trend, becoming smaller with increasing fluoride concentration. Fluoride was released from the zinc phosphate cements in processes that were diffusion based up to M(t)/M(infinity) of about 0.4. No further release occurred when specimens were placed in fresh volumes of deionised water. Only a fraction of the fluoride taken up was re-released, demonstrating that most of the fluoride taken up becomes irreversibly bound within the cement.

  12. Fluoride and nitrate removal from brackish groundwaters by batch-mode capacitive deionization.

    PubMed

    Tang, Wangwang; Kovalsky, Peter; He, Di; Waite, T David

    2015-11-01

    Capacitive deionization (CDI) is an emerging water desalination technology in which pairs of porous electrodes are electrically charged to remove ionic species from water. In this work, the feasibility of fluoride and nitrate removal from brackish groundwaters by batch-mode CDI was investigated. Initially, the effects of flow rate, initial fluoride concentration, and initial coexisting NaCl concentration on fluoride removal were studied. The steady-state fluoride concentration declined as the initial fluoride concentration decreased while initial NaCl concentration remained constant. Due to the competitive electrosorption between fluoride and chloride for limited pore surface sites, a higher initial chloride concentration resulted in a higher equilibrium dissolved fluoride concentration. A simplified one-dimensional transport model for dual anions was developed and found to reliably describe the dynamic process of removal of both fluoride and chloride ions in CDI cells over a range of well-defined operating conditions. Based on the ability of the model to describe fluoride removal, it was extended to description of nitrate removal from brackish groundwaters and also found to perform well. Thus, the approach to description of ion removal, at least in batch studies, appears robust and should assist in optimization of design and operating conditions such that optimal removal of trace ionic species is achieved even when high background concentrations of salt are present.

  13. THE EFFECT OF FLUORIDE ON CONVENTIONAL WATER TREATMENT USING ALUMINUM SULFATE

    EPA Science Inventory

    Based on the Information Collection Rule survey results of 600 large utilities, approximately 50% of them fluoridate their water and of those, 15-20% do so at the location of coagulant addition. In this case, the effect of fluoride on the coagulation process, floc properties, coa...

  14. Analytical Determination of Fluoride Ion Using Gran's Semi-Antilog Plot.

    ERIC Educational Resources Information Center

    Barnhard, Ralph J.

    1983-01-01

    A quantitative determination for fluoride ion using a commercially available fluoride electrode is described. The procedure referred to as known-addition is employed with the data processed on Gran's Plot Paper. Background information, experimental procedures, and advantages/disadvantages of the method are discussed. (JN)

  15. Discrimination of fluoride and phosphate contamination in central Florida for analyses of environmental effects

    NASA Technical Reports Server (NTRS)

    Coker, A. E.; Marshall, R.; Thomson, F.

    1972-01-01

    A study was made of the spatial registration of fluoride and phosphate pollution parameters in central Florida by utilizing remote sensing techniques. Multispectral remote sensing data were collected over the area and processed to produce multispectral recognition maps. These processed data were used to map land areas and waters containing concentrations of fluoride and phosphate. Maps showing distribution of affected and unaffected vegetation were produced. In addition, the multispectral data were processed by single band radiometric slicing to produce radiometric maps used to delineate areas of high ultraviolet radiance, which indicates high fluoride concentrations. The multispectral parameter maps and radiometric maps in combination showed distinctive patterns, which are correlated with areas known to be affected by fluoride and phosphate contamination. These remote sensing techniques have the potential for regional use to assess the environmental impact of fluoride and phosphate wastes in central Florida.

  16. A hybrid magnetic/complementary metal oxide semiconductor process design kit for the design of low-power non-volatile logic circuits

    NASA Astrophysics Data System (ADS)

    Di Pendina, G.; Prenat, G.; Dieny, B.; Torki, K.

    2012-04-01

    Since the advent of the MOS transistor, the performance of microelectronic circuits has followed Moore's law, stating that their speed and density would double every 18 months. Today, this trend tends to get out of breath: the continuously decreasing size of devices and increasing operation frequency result in power consumption and heating issues. Among the solutions investigated to circumvent these limitations, the use of non-volatile devices appears particularly promising. It allows easing, for example, the power gating technique, which consists in cutting-off the power supply of inactive blocks without losing information, drastically reducing the standby power consumption. In this approach, the advantages of magnetic tunnel junctions (MTJs) compared with other non-volatile devices allow one to design hybrid CMOS/magnetic circuits with high performance and new functionalities. Designing such circuits requires integrating MTJs in standard microelectronics design suites. This is performed by means of a process design kit (PDK) for the hybrid CMOS/magnetic technology. We present here a full magnetic PDK, which contains a compact model of the MTJ for electrical simulation, technology files for layout and physical verifications, and standard cells for the design of complex logic circuits and which is compatible with standard design suites. This PDK allows designers to accurately and comfortably design high-performance hybrid CMOS/magnetic logic circuits in the same way as standard CMOS circuits.

  17. Microwave-assisted chemical pre-treatment of waste sorghum leaves: Process optimization and development of an intelligent model for determination of volatile compound fractions.

    PubMed

    Rorke, Daneal C S; Suinyuy, Terence N; Gueguim Kana, E B

    2017-01-01

    This study reports the profiling of volatile compounds generated during microwave-assisted chemical pre-treatment of sorghum leaves. Compounds including acetic acid (0-186.26ng/g SL), furfural (0-240.80ng/g SL), 5-hydroxymethylfurfural (HMF) (0-19.20ng/g SL) and phenol (0-7.76ng/g SL) were detected. The reducing sugar production was optimized. An intelligent model based on Artificial Neural Networks (ANNs) was developed and validated to predict a profile of 21 volatile compounds under novel pre-treatment conditions. This model gave R(2)-values of up to 0.93. Knowledge extraction revealed furfural and phenol exhibited high sensitivity to acid- and alkali concentration and S:L ratio, while phenol showed high sensitivity to microwave duration and intensity. Furthermore, furfural production was majorly dependent on acid concentration and fit a dosage-response relationship model with a 2.5% HCl threshold. Significant non-linearities were observed between pre-treatment conditions and the profile of various compounds. This tool reduces analytical costs through virtual analytical instrumentation, improving process economics.

  18. Exposure of lima bean leaves to volatiles from herbivore-induced conspecific plants results in emission of carnivore attractants: active or passive process?

    PubMed

    Choh, Yasuyuki; Shimoda, Takeshi; Ozawa, Rika; Dicke, Marcel; Takabayashi, Junji

    2004-07-01

    There is increasing evidence that volatiles emitted by herbivore-damaged plants can cause responses in downwind undamaged neighboring plants, such as the attraction of carnivorous enemies of herbivores. One of the open questions is whether this involves an active (production of volatiles) or passive (adsorption of volatiles) response of the uninfested downwind plant. This issue is addressed in the present study. Uninfested lima bean leaves that were exposed to volatiles from conspecific leaves infested with the spider mite Tetranychus urticae, emitted very similar blends of volatiles to those emitted from infested leaves themselves. Treating leaves with a protein-synthesis inhibitor prior to infesting them with spider mites completely suppressed the production of herbivore-induced volatiles in the infested leaves. Conversely, inhibitor treatment to uninfested leaves prior to exposure to volatiles from infested leaves did not affect the emission of volatiles from the exposed, uninfested leaves. This evidence supports the hypothesis that response of the exposed downwind plant is passive. T. urticae-infested leaves that had been previously exposed to volatiles from infested leaves emitted more herbivore-induced volatiles than T. urticae-infested leaves previously exposed to volatiles from uninfested leaves. The former leaves were also more attractive to the predatory mite, Phytoseiulus persimilis, than the latter. This shows that previous exposure of plants to volatiles from herbivore-infested neighbors results in a stronger response of plants in terms of predator attraction when herbivores damage the plant. This supports the hypothesis that the downwind uninfested plant is actively involved. Both adsorption and production of volatiles can mediate the attraction of carnivorous mites to plants that have been exposed to volatiles from infested neighbors.

  19. 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.

  20. Volatile phytochemicals as mosquito semiochemicals

    PubMed Central

    Nyasembe, Vincent O.; Torto, Baldwyn

    2014-01-01

    Plant biochemical processes result in the release of an array of volatile chemical substances into the environment, some of which are known to play important plant fitness enhancing functions, such as attracting pollinators, thermal tolerance of photosynthesis, and defense against herbivores. Cunningly, phytophagous insects have evolved mechanisms to utilize these volatiles to their own advantage, either to colonize a suitable host for feeding, reproduction and oviposition or avoid an unsuitable one. The volatile compounds involved in plant–insect chemical interactions have been widely exploited in the management of agricultural pests. On the other hand, use of plant volatiles in the management of medically important insects is limited, mainly due to paucity of information on their role in disease vector–plant interactions. To date, a total of 29 plant volatile compounds from various chemical classes, including phenols, aldehydes, alcohols, ketones and terpenes, have been identified as mosquito semiochemicals. In this review, we present highlights of mosquito–plant interactions, the available evidence of nectar feeding, with particular emphasis on sources of plant attractants, methods of plant volatile collection and the candidate plant volatile compounds that attract mosquitoes to nectar sources. We also highlight the potential application of these phytochemical attractants in integrated mosquito management. PMID:25383131

  1. Design of the extraction process for terpenes and other volatiles from allspice by solid-phase microextraction and hydrodistillation.

    PubMed

    Bajer, Tomáš; Ligor, Magdalena; Ligor, Tomasz; Buszewski, Bogusław

    2016-02-01

    Methods for the separation and determination of terpenes (mono- and sesqui-) and phenylpropanoids such as eugenol and methyleugenol from samples of allspice berries have been developed. Chromatographic analyses of isolated groups of compounds were carried out by means of gas chromatography coupled with mass spectrometry. A comparison of various types of solid-phase microextraction fibers was performed. The highest yields of terpenes were extracted by polydimethylsiloxane and divinylbenzene/Carboxen/polydimethylsiloxane fibers (almost the same for these two fibers), approximately twice as much as by Carbowax/divinylbenzene fiber. The highest amounts of monoterpenes were extracted by divinylbenzene/Carboxen/polydimethylsiloxane fiber, and the highest amounts of sesquiterpenes were extracted by polydimethylsiloxane fiber. Moreover, the effect of water addition on extraction yields as well as time and temperature of extraction were tested. Aroma profiles of extracts obtained by solid-phase microextraction and essential oil obtained by hydrodistillation of allspice berries were compared. The aroma profile of the divinylbenzene/Carboxen/polydimethylsiloxane fiber extract was similar to the aroma profile of essential oil. Particular characteristics of volatile allspice matters were presented. The linear retention indices for each compound were calculated.

  2. Compound specific carbon and hydrogen stable isotope analyses of volatile organic compounds in various emissions of combustion processes.

    PubMed

    Vitzthum von Eckstaedt, Christiane D; Grice, Kliti; Ioppolo-Armanios, Marisa; Kelly, David; Gibberd, Mark

    2012-11-01

    This study presents carbon (δ(13)C) and hydrogen (δD) isotope values of volatile organic compounds (VOCs) in various emission sources using thermal desorption-gas chromatography-isotope ratio mass spectrometry (TD-GC-irMS). The investigated VOCs ranged from C6 to C10. Samples were taken from (i) car exhaust emissions as well as from plant combustion experiments of (ii) various C3 and (iii) various C4 plants. We found significant differences in δ values of analysed VOCs between these sources, e.g. δ(13)C of benzene ranged between (i) -21.7 ± 0.2 ‰, (ii) -27.6 ± 1.6 ‰ and (iii) -16.3 ± 2.2 ‰, respectively and δD of benzene ranged between (i) -73 ± 13 ‰, (ii) -111 ± 10 ‰ and (iii) -70 ± 24 ‰, respectively. Results of VOCs present in investigated emission sources were compared to values from the literature (aluminium refinery emission). All source groups could be clearly distinguished using the dual approach of δ(13)C and δD analysis. The results of this study indicate that the correlation of compound specific carbon and hydrogen isotope analysis provides the potential for future research to trace the fate and to determine the origin of VOCs in the atmosphere using thermal desorption compound specific isotope analysis.

  3. 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

  4. 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.

  5. Chronic Fluoride Toxicity: Dental Fluorosis

    PubMed Central

    DenBesten, Pamela; Li, Wu

    2012-01-01

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

  6. Change in Color and Volatile Composition of Skim Milk Processed with Pulsed Electric Field and Microfiltration Treatments or Heat Pasteurization †

    PubMed Central

    Chugh, Anupam; Khanal, Dipendra; Walkling-Ribeiro, Markus; Corredig, Milena; Duizer, Lisa; Griffiths, Mansel W.

    2014-01-01

    Non-thermal processing methods, such as pulsed electric field (PEF) and tangential-flow microfiltration (TFMF), are emerging processing technologies that can minimize the deleterious effects of high temperature short time (HTST) pasteurization on quality attributes of skim milk. The present study investigates the impact of PEF and TFMF, alone or in combination, on color and volatile compounds in skim milk. PEF was applied at 28 or 40 kV/cm for 1122 to 2805 µs, while microfiltration (MF) was conducted using membranes with three pore sizes (lab-scale 0.65 and 1.2 µm TFMF, and pilot-scale 1.4 µm MF). HTST control treatments were applied at 75 or 95 °C for 20 and 45 s, respectively. Noticeable color changes were observed with the 0.65 µm TFMF treatment. No significant color changes were observed in PEF-treated, 1.2 µm TFMF-treated, HTST-treated, and 1.4 µm MF-treated skim milk (p ≥ 0.05) but the total color difference indicated better color retention with non-thermal preservation. The latter did not affect raw skim milk volatiles significantly after single or combined processing (p ≥ 0.05), but HTST caused considerable changes in their composition, including ketones, free fatty acids, hydrocarbons, and sulfur compounds (p < 0.05). The findings indicate that for the particular thermal and non-thermal treatments selected for this study, better retention of skim milk color and flavor components were obtained for the non-thermal treatments. PMID:28234317

  7. Economic process to produce biohydrogen and volatile fatty acids by a mixed culture using vinasse from sugarcane ethanol industry as nutrient source.

    PubMed

    Sydney, Eduardo Bittencourt; Larroche, Christian; Novak, Alessandra Cristine; Nouaille, Regis; Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Letti, Luiz Alberto; Soccol, Vanete Thomaz; Soccol, Carlos Ricardo

    2014-05-01

    This work evaluates the potential of vinasse (a waste obtained at the bottom of sugarcane ethanol distillation columns) as nutrient source for biohydrogen and volatile fatty acids production by means of anaerobic consortia. Two different media were proposed, using sugarcane juice or molasses as carbon source. The consortium LPBAH1 was selected for fermentation of vinasse supplemented with sugarcane juice, resulting in a higher H2 yield of 7.14 molH2 molsucrose(-1) and hydrogen content in biogas of approx. 31%, while consortium LPBAH2 resulted in 3.66 molH2/molsucrose and 32.7% hydrogen content in biogas. The proposed process showed a rational and economical use for vinasse, a mandatory byproduct of the renewable Brazilian energy matrix.

  8. Zonation of volatile and major elements in basaltic melt inclusions: a snapshot of syn-eruptive processes

    NASA Astrophysics Data System (ADS)

    Newcombe, M.; Fabbrizio, A.; Zhang, Y.; Le Voyer, M.; Guan, Y.; Ma, C.; Eiler, J. M.; Saal, A. E.; Stolper, E. M.

    2011-12-01

    Significant zonation in volatile and major elements has been discovered in olivine-hosted melt inclusions (MIs) from glassy pillow margins from the Siqueiros Fracture Zone [samples previously studied in 1]. For the most part, components that are compatible in olivine (e.g. MgO) are depleted at the edges of the zoned MIs relative to their centers, whereas components that are incompatible in olivine (e.g. Al2O3, SiO2, Na2O, and S) are enriched near the MI edges. H2O and F are exceptions in that they are incompatible, yet in several MIs they are depleted near the olivine-melt boundary. FeO and CaO are also exceptions in that they show complex features attributable to uphill diffusion. Another complexity is the similarity between the shapes of the SiO2 and Na2O profiles (despite significant differences in measured self and tracer diffusivities of these components [2, 3]), suggesting that the diffusion of these components is strongly coupled. All MIs from this sample suite exhibit zoning profiles, as do a suite of MIs from the Galapagos Islands and the inclusions studied in [4], so this feature may be common in rapidly quenched, glassy inclusions. Preservation of strong zonation in the Siqueiros MIs suggests that it formed in response to crystallization of olivine on the walls of the MIs during or just prior to eruption because, based on known diffusion coefficients, such profiles would be erased by diffusion on time scales on the order of 1 hr. The MgO concentration profiles in several Siqueiros MIs have been used to constrain the cooling history of the inclusions using the results of [5]. The profiles are consistent with an initial slow cooling rate followed by a period of more rapid cooling over a total timescale of ~10 min. Given that they are incompatible in olivine, the observed decreases in the concentrations of H2O and F toward the edges of some Siqueiros inclusions could suggest either uphill diffusion of H2O and F (as observed for H2O in [6] in a granitic

  9. Pronounced reduction of fluoride exposure in free-ranging deer in North Bohemia (Czech Republic) as indicated by the biomarkers skeletal fluoride content and dental fluorosis.

    PubMed

    Kierdorf, Uwe; Bahelková, Petra; Sedláček, František; Kierdorf, Horst

    2012-01-01

    Wild deer have been recommended as bioindicators of fluoride pollution. We compared bone fluoride concentrations and prevalence and severity of dental fluorosis in free-ranging European roe deer (Capreolus capreolus) and red deer (Cervus elaphus) from five counties in the northwestern part of the Czech Republic that had been collected by hunters and whose mandibles were presented at trophy exhibitions in the years 1996/1997 ("early period") and 2009 ("late period"). Data on atmospheric fluoride deposition suggested that the deer from the early period had been exposed to markedly higher fluoride levels than those from the late period. We therefore predicted a decline in skeletal fluoride levels and prevalence of dental fluorosis for both species from the early to the late period. Fluoride concentrations were determined in the coronoid process of the mandible, and assessment of dental fluorosis was performed on the permanent cheek teeth. A pronounced drop in fluoride concentrations from the early period (roe deer (n = 157), median: 3147 mg F(-)/kg of dry bone; red deer (n = 127), median: 1263 mg F(-)/kg of dry bone) to the late period (roe deer (n = 117), median: 350 mg F(-)/kg of dry bone; red deer (n = 72), median: 288 mg F(-)/kg of dry bone) was recorded. Prevalence of dental fluorosis also markedly declined from the early to the late period (roe deer: from 93% to 12%, red deer: from 87% to 28%). The reduction of fluoride deposition in the study area and, in consequence, fluoride exposure of the resident deer populations, is attributed largely to the implementation of emission control devices in the brown coal-fired power plants located in North Bohemia from the mid 1990s onwards. The findings of the present study demonstrate that wild deer are well suited for monitoring temporal changes in fluoride pollution of their habitats.

  10. [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.

  11. EMERGING TECHNOLOGY BULLETIN: PROCESS FOR THE TREATMENT OF VOLATILE ORGANIC CARBON AND HEAVY-METAL- CONTAMINATED SOIL - INTERNATIONAL TECHNOLOGY CORPORATION

    EPA Science Inventory

    The batch steam distillation and metal extraction treatment process is a two-stage system that treats soils contaminated with organics and inorganics. This system uses conventional, readily available process equipment, and does not produce hazardous combustion products. Hazar...

  12. Multifractal diffusion entropy analysis on stock volatility in financial markets

    NASA Astrophysics Data System (ADS)

    Huang, Jingjing; Shang, Pengjian; Zhao, Xiaojun

    2012-11-01

    This paper introduces a generalized diffusion entropy analysis method to analyze long-range correlation then applies this method to stock volatility series. The method uses the techniques of the diffusion process and Rényi entropy to focus on the scaling behaviors of regular volatility and extreme volatility respectively in developed and emerging markets. It successfully distinguishes their differences where regular volatility exhibits long-range persistence while extreme volatility reveals anti-persistence.

  13. Fluoride removal by a continuous flow electrocoagulation reactor.

    PubMed

    Emamjomeh, Mohammad M; Sivakumar, Muttucumaru

    2009-02-01

    Long-term consumption of water containing excessive fluoride can lead to fluorosis of the teeth and bones. Electrocoagulation (EC) is an electrochemical technique, in which a variety of unwanted dissolved particles and suspended matter can be effectively removed from an aqueous solution by electrolysis. Continuous flow experiments with monopolar aluminium electrodes for fluoride removal were undertaken to investigate the effects of the different parameters such as: current density (12.5-50A/m(2)), flow rate (150-400 mL/min), initial pH (4-8), and initial fluoride concentration (5-25mg/L). The highest treatment efficiency was obtained for the largest current and the removal efficiency was found to be dependent on the current density, the flow rate and the initial fluoride concentration when the final pH ranged between 6 and 8. The composition of the sludge produced was analysed using the X-ray diffraction (XRD) spectrum. The strong presence of the aluminium hydroxide [Al(OH)(3)] in the above pH range, which maximizes the formation of aluminium fluoride hydroxide complex [Al(n)F(m)(OH)(3n-m)], is the main reason for defluoridation by electrocoagulation. The results obtained showed that the continuous flow electrocoagulation technology is an effective process for defluoridation of potable water supplies and could also be utilized for the defluoridation of industrial wastewater.

  14. Industrial Applications of Graphite Fluoride Fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Kucera, Donald

    1991-01-01

    Based on fluorination technology developed during 1934 to 1959, and the fiber technology developed during the 1970s, a new process was developed to produce graphite fluoride fibers. In the process, pitch based graphitized carbon fibers are at first intercalated and deintercalated several times by bromine and iodine, followed by several cycles of nitrogen heating and fluorination at 350 to 370 C. Electrical, mechanical, and thermal properties of this fiber depend on the fluorination process and the fluorine content of the graphite fluoride product. However, these properties are between those of graphite and those of PTFE (Teflon). Therefore, it is considered to be a semiplastic. The physical properties suggest that this new material may have many new and unexplored applications. For example, it can be a thermally conductive electrical insulator. Its coefficient of thermal expansion (CTE) can be adjusted to match that of silicon, and therefore, it can be a heat sinking printed circuit board which is CTE compatible with silicon. Using these fibers in printed circuit boards may provide improved electrical performance and reliability of the electronics on the board over existing designs. Also, since it releases fluorine at 300 C or higher, it can be used as a material to store fluorine and to conduct fluorination. This application may simplify the fluorination process and reduce the risk of handling fluorine.

  15. An Overview of Liquid Fluoride Salt Heat Transport Systems

    SciTech Connect

    Holcomb, David Eugene; Cetiner, Sacit M

    2010-09-01

    Heat transport is central to all thermal-based forms of electricity generation. The ever increasing demand for higher thermal efficiency necessitates power generation cycles transitioning to progressively higher temperatures. Similarly, the desire to provide direct thermal coupling between heat sources and higher temperature chemical processes provides the underlying incentive to move toward higher temperature heat transfer loops. As the system temperature rises, the available materials and technology choices become progressively more limited. Superficially, fluoride salts at {approx}700 C resemble water at room temperature being optically transparent and having similar heat capacity, roughly three times the viscosity, and about twice the density. Fluoride salts are a leading candidate heat-transport material at high temperatures. Fluoride salts have been extensively used in specialized industrial processes for decades, yet they have not entered widespread deployment for general heat transport purposes. This report does not provide an exhaustive screening of potential heat transfer media and other high temperature liquids such as alkali metal carbonate eutectics or chloride salts may have economic or technological advantages. A particular advantage of fluoride salts is that the technology for their use is relatively mature as they were extensively studied during the 1940s-1970s as part of the U.S. Atomic Energy Commission's program to develop molten salt reactors (MSRs). However, the instrumentation, components, and practices for use of fluoride salts are not yet developed sufficiently for commercial implementation. This report provides an overview of the current understanding of the technologies involved in liquid salt heat transport (LSHT) along with providing references to the more detailed primary information resources. Much of the information presented here derives from the earlier MSR program. However, technology has evolved over the intervening years, and

  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. Potential exposure and risk of fluoride intakes from tea drinks produced in Taiwan.

    PubMed

    Lung, Shih-Chun Candice; Cheng, Hui-Wen; Fu, Chi Betsy

    2008-03-01

    Tea is the second most commonly consumed drink in the world. Excess fluoride intakes from tea drinks may cause health effects. This work assesses infusible fluoride levels in popular tea sold in Taiwan and evaluates potential exposure factors. Lungjing, pouchong, tienguanyin, oolong, pureh, and black tea specimens were purchased from different counties in Taiwan. Fluoride levels were evaluated in one complete cycle of tea making as well as at different calcium carbonate contents in water, with glass or porcelain teapots, and with/without adding sugar. Oolong tea leaves in each manufacturing step were also analyzed for infusible fluoride. Potential fluoride intakes and risks are estimated based on a national survey. Among six kinds of tea, black tea had the highest fluoride concentrations (8.64+/-2.96 mg/l), whereas pureh (1.97+/-2.70 mg/l) had the lowest levels. Higher percentages of infusible fluoride can be rinsed away from tea leaves curved lengthways compared to those curved end-to-end in the first 2.5 min. The use of glass or porcelain teapots and calcium carbonate content (up to 400 mg/l) in water would not affect infusible fluoride levels, whereas adding sugar increased the infusible fluoride in the first few minutes. In addition, it was found that the critical step during the manufacturing process affecting the percentage of infusible fluoride was ball rolling rather than fermentation. Furthermore, intakes of high amounts (> or =5 l/week) of certain tea may result in excess risks of dental or skeletal fluorosis. Tea lovers could be exposed to excess fluoride and may be at risk of fluorosis.

  19. 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

  20. Benefits of a silica-based fluoride toothpaste containing o-cymen-5-ol, zinc chloride and sodium fluoride.

    PubMed

    Newby, Craig S; Rowland, Joanna L; Lynch, Richard J M; Bradshaw, David J; Whitworth, Darren; Bosma, Mary Lynn

    2011-08-01

    Fluoride toothpastes in conjunction with tooth brushing are used to clean teeth, control plaque build-up and for anti-caries benefits. Toothpastes are designed with attractive flavours and appearances to encourage regular prolonged use to maximise these benefits. The incorporation of additional ingredients into toothpaste is a convenient way to provide supplementary protection that fits into people's everyday oral care routine. Such ingredients should not compromise the primary health benefits of toothpaste nor discourage its use. o-Cymen-5-ol and zinc chloride have been incorporated into a sodium fluoride (NaF)/silica toothpaste at 0.1%w/w and 0.6%w/w respectively to provide additional benefits. These include improved gingival health maintenance, in terms of the reduction of plaque, gingival index and bleeding, and an immediate and long lasting reduction in volatile sulfur compounds (VSCs) measured on breath. These benefits can be attributed to the antimicrobial and neutralisation actions of the toothpaste. The use of established fluoride models demonstrated no compromise in NaF bioavailability. The toothpaste was formulated without compromising product aesthetics. The combination of o-cymen-5-ol and zinc chloride in toothpaste gave superior maintenance of gingival health and reduction in malodour related VSCs without compromising the primary health benefits of the toothpaste or diminishing attributes preferred for the product's use.

  1. 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)

  2. 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…

  3. 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)

  4. Volatile organic compound flux from manure of cattle fed diets differing in grain processing method and co-product inclusion

    NASA Astrophysics Data System (ADS)

    Hales, Kristin; Parker, David B.; Cole, N. Andy

    2015-01-01

    Odor emissions from livestock production have become increasingly important in the past decade. Odors derived from animal feeding operations are caused by odorous VOC emitted from the mixture of feces and urine, as well as feed and silage which may be experiencing microbial fermentation. Distillers grains are a by-product of corn grain fermentation used to produce fuel ethanol, and this industry has grown rapidly throughout the U.S. in past years. Therefore, the use of wet distillers grains with solubles (WDGS) in feedlot cattle diets has also increased. The objective of this research was to determine specific VOC emissions from feces and urine or a mixture of both, from cattle fed steam flaked or dry-rolled corn (DRC)-based diets containing either 0% or 30% WDGS. Flux of dimethyl trisulfide was greater from feces of cattle fed DRC than steam-flaked corn (SFC) diets. No other differences in flux from feces were detected across dietary treatments for phenol, 4-methylphenol, indole, skatole, dimethyl disulfide, and flux of volatile fatty acids (VFA) such as acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids (P > 0.15). Flux of skatole, acetic acid, and valeric acid from urine was greater for cattle fed SFC than DRC diets (P < 0.05). Moreover, dimethyl disulfide flux was greater for cattle fed DRC vs. SFC diets (P = 0.05). When evaluating WDGS inclusion in the diet, flux of acetic acid and heptanoic acid from urine was greater when cattle were fed diets containing 0% WDGS than 30% WDGS (P < 0.05). When combining urine and feces in the ratio in which they were excreted from the animal, flux of propionic acid was greater when cattle were fed DRC vs. SFC diets (P = 0.05). Based on these results, the majority of the VOC, VFA, and odor flux from cattle feeding operations is from the urine. Therefore, dietary strategies to reduce odor from cattle feeding facilities should primarily focus on reducing excretion of odorous compounds in the urine.

  5. The Oxidation State of Global Subduction Zone Basalts and its Relationship to Volatiles, Magmatic Processes, and Source Composition

    NASA Astrophysics Data System (ADS)

    Kelley, K. A.; Cottrell, E.

    2008-12-01

    Oxidation state is a central variable in magmatic systems. In subduction zones, the mantle wedge is exposed to hydrous fluids from an oxidized subducting plate, potentially driving a fundamental shift in the oxidation states of arc and back-arc basin magmas and their sources. Despite its importance, however, magmatic oxidation state and its relationship to conditions in the mantle source can be difficult to constrain. Here, we present new, in-situ μ-XANES analyses of Fe+3/ΣFe ratios, as an indicator of melt oxidation state, in natural, primitive pillow glasses from the Mariana, Lau, and Manus back-arc basins (MgO>6 wt.%; n=31) and a global suite of olivine-hosted arc melt inclusions (MI; MgO>4 wt.%; n=16). These new data show that back-arc basin basalts preserve Fe+3/ΣFe ratios of 0.14-0.21, more oxidized than MORB (Fe+3/ΣFe=0.11-0.17), and arc basalts range to even higher ratios of 0.17-0.36. Analysis of MI equilibrium with host olivine compositions indicates that either post-entrapment crystallization or outward Fe+2 diffusion may have occurred in the MI's studied, but the magnitude of these effects is small (9±5% change in FeO; see also Cottrell & Kelley, this mtg.). Coupled with new and existing major element, volatile (H2O±CO2, S, Cl, F), and trace element data, we also test the variation of melt oxidation state with indicators of extent of crystal fractionation and of mantle source composition. The arc and back-arc glasses capture a full range of natural, undegassed magmatic H2O concentrations (0.1-5.3 wt.%), and show a general, global increase in Fe+3/ΣFe with increasing H2O content, although the Mariana trough defines a trend distinct from the Manus and Lau basins. The Fe+3/ΣFe ratio does not correlate with Mg#, suggesting that the melt oxidation states are not controlled by the extent of crystal fractionation. In the Mariana trough, Fe+3/ΣFe does increase with increasing Ba and Sr concentrations, suggesting a direct link between melt oxidation

  6. Chemical differentiation of volatile compounds in crude and processed Atractylodis Macrocephalae Rhizoma by using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry combined with multivariate data analysis.

    PubMed

    Cao, Gang; Cai, Hao; Jiang, Jianping; Yao, Linjiang; Tu, Sicong; Wang, Lin; Ma, Xiaoqing; Cai, Baochang

    2014-05-01

    In the present study, comprehensive 2D GC-TOF-MS combined with multivariate data analysis was applied to analyze the differences of the volatile components in crude and processed Atractylodis Macrocephalae Rhizoma (AMR) samples. As a result, 26 compounds that were found in crude AMR samples disappeared in processed AMR samples, and 19 compounds were newly generated and identified in AMR after processing with wheat bran. Meanwhile, principal component analysis demonstrated that there were significant chemical differences between crude and processed AMR samples, and processing procedure caused obvious quantitative and qualitative changes of volatile components in AMR. The established method could be used to explain the chemical differentiation between crude and processed AMR, and to further understand the processing mechanism of herbal medicines.

  7. [Public water supply fluoridation in Brazil according to health sector leaders].

    PubMed

    Ferreira, Regina Glaucia Lucena Aguiar; Bógus, Cláudia Maria; Marques, Regina Auxiliadora de Amorim; Menezes, Léa Maria Bezerra de; Narvai, Paulo Capel

    2014-09-01

    Various groups have opposed water supply fluoridation in Brazil, while others have supported the measure based on scientific evidence. This article describes the perceptions of delegates to the 13th National Health Conference on mandatory fluoridation of the country's public water supply. Interviews were processed using collective subject discourse analysis. A certain degree of misinformation persists regarding basic characteristics of water fluoridation, which is frequently confused with chlorination. The delegates' discourses showed a continuing need for public awareness-raising regarding fluoridation and the delegates' desire that the National Congress not take measures impacting public health without consulting society's stakeholders. However, most of the interviewees agreed that to repeal mandatory water fluoridation or loosen the control of its implementation could increase the incidence of tooth decay in the population.

  8. Determination of bioavailable fluoride from sepiolite by "in vivo" digestibility assays.

    PubMed

    Suárez, P; Quintana, M C; Hernández, L

    2008-02-01

    This work presents a study of the bioavailability and distribution of fluoride in tissues of animals (Wistar rats) which were fed with a poultry feeding that contains sepiolite as an additive. The determination of fluoride concentration was carried out by potentiometric measurements using a fluoride selective electrode. The quantification was done using the standard addition method with enough accuracy and precision in all the assays. The results demonstrate that fluoride present in sepiolite is not bioavailable. The digestion process does not extract all the fluoride from sepiolite, so sepiolite can be use in poultry feedings without any risk. These studies have contributed to the discussions at EU level about extraction procedures and F(-) determination in feed material of mineral origin.

  9. 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.

  10. Advanced treatment of residual nitrogen from biologically treated coke effluent by a microalga-mediated process using volatile fatty acids (VFAs) under stepwise mixotrophic conditions.

    PubMed

    Ryu, Byung-Gon; Kim, Woong; Heo, Sung-Woon; Kim, Donghyun; Choi, Gang-Guk; Yang, Ji-Won

    2015-09-01

    This work describes the development of a microalga-mediated process for simultaneous removal of residual ammonium nitrogen (NH4(+)-N) and production of lipids from biologically treated coke effluent. Four species of green algae were tested using a sequential mixotrophic process. In the first phase-CO2-supplied mixotrophic condition-all microalgae assimilated NH4(+)-N with no evident inhibition. In second phase-volatile fatty acids (VFAs)-supplied mixotrophic condition-removal rates of NH4(+)-N and biomass significantly increased. Among the microalgae used, Arctic Chlorella sp. ArM0029B had the highest rate of NH4(+)-N removal (0.97 mg/L/h) and fatty acid production (24.9 mg/L/d) which were 3.6- and 2.1-fold higher than those observed under the CO2-supplied mixotrophic condition. Redundancy analysis (RDA) indicated that acetate and butyrate were decisive factors for increasing NH4(+)-N removal and fatty acid production. These results demonstrate that microalgae can be used in a sequential process for treatment of residual nitrogen after initial treatment of activated sludge.

  11. Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) mitigation in the pyrolysis process of waste tires using CO₂ as a reaction medium.

    PubMed

    Kwon, Eilhann E; Oh, Jeong-Ik; Kim, Ki-Hyun

    2015-09-01

    Our work reported the CO2-assisted mitigation of PAHs and VOCs in the thermo-chemical process (i.e., pyrolysis). To investigate the pyrolysis of used tires to recover energy and chemical products, the experiments were conducted using a laboratory-scale batch-type reactor. In particular, to examine the influence of the CO2 in pyrolysis of a tire, the pyrolytic products including C1-5-hydrocarbons (HCs), volatile organic carbons (VOCs), and polycyclic aromatic hydrocarbons (PAHs) were evaluated qualitatively by gas chromatography (GC) with mass spectroscopy (MS) as well as with a thermal conductivity detector (TCD). The mass balance of the pyrolytic products under various pyrolytic conditions was established on the basis of their weight fractions of the pyrolytic products. Our experimental work experimentally validated that the amount of gaseous pyrolytic products increased when using CO2 as a pyrolysis medium, while substantially altering the production of pyrolytic oil in absolute content (7.3-17.2%) and in relative composition (including PAHs and VOCs). Thus, the co-feeding of CO2 in the pyrolysis process can be considered an environmentally benign and energy efficient process.

  12. The variation of volatile fatty acid compositions in sewer length, and its effect on the process design of biological nutrient removal.

    PubMed

    Yun, Z; Yun, G H; Lee, H S; Yoo, T U

    2013-01-01

    The potential of enhanced biological phosphorus removal (EBPR) in biological nutrient removal (BNR) systems critically depends on the availability and types of volatile fatty acids (VFAs) in sewage. Although the characteristics of VFAs in sewage are strongly related with the biochemical transformations in the sewer system, they have not been studied thoroughly in terms of BNR process design. We have investigated the characteristics of VFAs in influent of nine sewage treatment plants which represent typical small to very large sewer systems in Korea. We found that influent total VFACOD (VFA as chemical oxygen demand) concentrations ranged from 20.4 to 65.2 mg/L. Acetic acid was a predominant VFA in sewage, and the propionic acid (HPr) portion averaged 38.7% of total VFACOD. However the sewage from longer sewer systems showed more HPr content, indicating that type of VFA varied with the total sewer length. The finding is a particularly important consideration for BNR process design since availability of HPr positively behaved to suppress the unfavorable growth of glycogen-accumulating organisms. The implication of these findings for BNR process design is discussed in this paper.

  13. PILOT-SCALE REMOVAL OF FLUORIDE FROM LEGACY PLUTONIUM MATERIALS USING VACUUM SALT DISTILLATION

    SciTech Connect

    Pierce, R. A.; Pak, D. J.

    2012-09-11

    Between September 2009 and January 2011, the Savannah River National Laboratory (SRNL) and HB-Line designed, developed, tested, and successfully deployed a system for the distillation of chloride salts. In 2011, SRNL adapted the technology for the removal of fluoride from fluoride-bearing salts. The method involved an in situ reaction between potassium hydroxide (KOH) and the fluoride salt to yield potassium fluoride (KF) and the corresponding oxide. The KF and excess KOH can be distilled below 1000{deg}C using vacuum salt distillation (VSD). The apparatus for vacuum distillation contains a zone heated by a furnace and a zone actively cooled using either recirculated water or compressed air. During a vacuum distillation operation, a sample boat containing the feed material is placed into the apparatus while it is cool, and the system is sealed. The system is evacuated using a vacuum pump. Once a sufficient vacuum is attaned, heating begins. Volatile salts distill from the heated zone to the cooled zone where they condense, leaving behind the non-volatile material in the feed boat. Studies discussed in this report were performed involving the use of non-radioactive simulants in small-scale and pilot-scale systems as well as radioactive testing of a small-scale system with plutonium-bearing materials. Aspects of interest include removable liner design considerations, boat materials, in-line moisture absorption, and salt deposition.

  14. 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.

  15. Heterogeneous processing of biomass burning aerosol proxies by OH radicals for a wide range of OH concentrations and detection of volatilization products

    NASA Astrophysics Data System (ADS)

    Slade, J. H.; Knopf, D. A.

    2012-12-01

    Biomass burning aerosol (BBA) constitutes the majority of primary organic aerosol found in the atmosphere, with emission rates comparable to fossil-fuel burning. BBA affects earth's radiative budget directly through absorption and scattering of radiation or indirectly by modifying cloud radiative properties, and impacts air quality. Quantifying BBA source strength and thus its effects on air quality, human health, and climate can be difficult since these organic particles can chemically transform during atmospheric transport, a process also termed aging, due to heterogeneous reactions with oxidants and radicals such as OH. In this work we investigate the reactive uptake of OH radicals by typical BBA compounds that also serve as molecular markers for source apportionment studies. Organic substrates of cellulose pyrolysis products such as levoglucosan (1,6-anhydro-β-glucopyranose, C6H10O5), resin acids such as abietic acid (1-phenanthrenecarboxylic acid, C20H30O2), and lignin decomposition products such as 5-nitroguaiacol (2-methoxy-5-nitrophenol, C7H7NO4) have been exposed to a wide range of OH concentrations (~107-1011 cm-3), in presence of O2 in a rotating wall flow reactor operated at 2-6 mbar coupled to a custom built chemical ionization mass spectrometer (CIMS). OH radicals were generated through H2 dissociation in an Evenson microwave resonant cavity operated at 2.45 GHz followed by reaction with O2 or NO2. In addition, potential volatilization of organic material due to heterogeneous oxidation by OH has been determined in-situ by monitoring the volatile organic compounds using a high resolution-proton transfer reaction-time of flight-mass spectrometer (HR-PTR-ToF-MS). The volatilization studies are conducted at 1 atm and OH is generated by O3 photolysis in the presence of H2O vapor and quantified using a photochemical box model as well as through reaction with a known concentration of isoprene (2-methyl-1,3-butadiene, C5H8). Reactive uptake validation

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. 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

  1. 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.

  2. 75 FR 60013 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Control of Volatile...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-29

    ... Volatile Organic Compounds Emissions From Industrial Solvent Cleaning Operations AGENCY: Environmental... consists of an addition to Maryland's Volatile Organic Compounds from Specific Processes Regulation... available control techniques (RACT) requirements for sources of volatile organic compounds (VOCs) covered...

  3. 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.

  4. 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

  5. Assessment of processes controlling the regional distribution of fluoride and arsenic in groundwater of the Pampeano Aquifer in the Del Azul Creek basin (Argentina)

    NASA Astrophysics Data System (ADS)

    Zabala, M. E.; Manzano, M.; Vives, L.

    2016-10-01

    Groundwater in the upper 50 m of the Pampeano Aquifer in the Del Azul Creek basin (Argentina) has F and As contents above the WHO safe drinking levels. This basin is situated to the SE of the Chaco-Pampean plain, in Buenos Aires Province. The Pampeano Aquifer is a major water source for all uses. The aim of the study is to assess the primary processes controlling the regional distribution of F and As in the most exploited part of the aquifer. The study involved sampling for chemical and isotopic analyses, interpretation of data with different methods (diagrams, bivariate analyses, mineral saturation states, Principal Component Analysis) and deduction of leading processes. Information about aquifer mineralogy and hydrogeochemical processes involved in F and As solubilization in the aquifer has been taken from previous works of the same and other authors. Groundwater salinity increases to the NE, in the direction of the regional groundwater flow. Chemical types evolve from Ca/Mg-HCO3 in the upper part of the basin, to Na-HCO3 in the middle part and to Na-ClSO4 and Na-Cl in the lower part. The regional distribution of F is controlled by hydrogeochemical processes. The distribution of As is controlled by two types of processes dominating in different areas: hydrogeochemical controls prevail in the low to moderately mineralized groundwater of the middle and lower parts of the basin; hydrogeological controls lead to the NE of the lower basin and beyond it. In the last zone there are abundant lagoons and seasonal flooding is frequent, making evapoconcentration an important process for groundwater mineralization. The main hydrogeochemical processes involved in both F and As distribution are cation exchange, with Na release and Ca uptake, carbonate dissolution and pH increase. Arsenic release induced by redox processes may play to the NE, but its results would be masked by the effect of evaporation.

  6. 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

  7. Contents of fluorides in vegetables from areas contaminated by industrial emissions: a preliminary report

    SciTech Connect

    Machoy, Z.; Samujlo, D.

    1981-01-01

    In vegetables grown in 1978 and 1979 near a chemical plant where phosphorites and apatites are processed, according to preliminary data, fluoride was significantly elevated in roots of carrots and parsley and in the leaves of parsley.

  8. Active Flash: Performance-Energy Tradeoffs for Out-of-Core Processing on Non-Volatile Memory Devices

    SciTech Connect

    Boboila, Simona; Kim, Youngjae; Vazhkudai, Sudharshan S; Desnoyers, Peter; Shipman, Galen M

    2012-01-01

    In this abstract, we study the performance and energy tradeoffs involved in migrating data analysis into the flash device, a process we refer to as Active Flash. The Active Flash paradigm is similar to 'active disks', which has received considerable attention. Active Flash allows us to move processing closer to data, thereby minimizing data movement costs and reducing power consumption. It enables true out-of-core computation. The conventional definition of out-of-core solvers refers to an approach to process data that is too large to fit in the main memory and, consequently, requires access to disk. However, in Active Flash, processing outside the host CPU literally frees the core and achieves real 'out-of-core' analysis. Moving analysis to data has long been desirable, not just at this level, but at all levels of the system hierarchy. However, this requires a detailed study on the tradeoffs involved in achieving analysis turnaround under an acceptable energy envelope. To this end, we first need to evaluate if there is enough computing power on the flash device to warrant such an exploration. Flash processors require decent computing power to run the internal logic pertaining to the Flash Translation Layer (FTL), which is responsible for operations such as address translation, garbage collection (GC) and wear-leveling. Modern SSDs are composed of multiple packages and several flash chips within a package. The packages are connected using multiple I/O channels to offer high I/O bandwidth. SSD computing power is also expected to be high enough to exploit such inherent internal parallelism within the drive to increase the bandwidth and to handle fast I/O requests. More recently, SSD devices are being equipped with powerful processing units and are even embedded with multicore CPUs (e.g. ARM Cortex-A9 embedded processor is advertised to reach 2GHz frequency and deliver 5000 DMIPS; OCZ RevoDrive X2 SSD has 4 SandForce controllers, each with 780MHz max frequency

  9. Facile fabrication of highly ordered poly(vinylidene fluoride-trifluoroethylene) nanodot arrays for organic ferroelectric memory

    NASA Astrophysics Data System (ADS)

    Fang, Huajing; Yan, Qingfeng; Geng, Chong; Chan, Ngai Yui; Au, Kit; Yao, Jianjun; Ng, Sheung Mei; Leung, Chi Wah; Li, Qiang; Guo, Dong; Wa Chan, Helen Lai; Dai, Jiyan

    2016-01-01

    Nano-patterned ferroelectric materials have attracted significant attention as the presence of two or more thermodynamically equivalent switchable polarization states can be employed in many applications such as non-volatile memory. In this work, a simple and effective approach for fabrication of highly ordered poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) nanodot arrays is demonstrated. By using a soft polydimethylsiloxane mold, we successfully transferred the 2D array pattern from the initial monolayer of colloidal polystyrene nanospheres to the imprinted P(VDF-TrFE) films via nanoimprinting. The existence of a preferred orientation of the copolymer chain after nanoimprinting was confirmed by Fourier transform infrared spectra. Local polarization switching behavior was measured by piezoresponse force microscopy, and each nanodot showed well-formed hysteresis curve and butterfly loop with a coercive field of ˜62.5 MV/m. To illustrate the potential application of these ordered P(VDF-TrFE) nanodot arrays, the writing and reading process as non-volatile memory was demonstrated at a relatively low voltage. As such, our results offer a facile and promising route to produce arrays of ferroelectric polymer nanodots with improved piezoelectric functionality.

  10. 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)...

  11. Effects of processing methods on composition and functionality of volatile components isolated from immature fruits of atemoya.

    PubMed

    Liu, Tai-Ti; Chao, Louis Kuo-Ping; Peng, Chi-Wei; Yang, Tsung-Shi

    2016-07-01

    Atemoya is one of the most important commercial fruits of the family Annonaceae. The immature fruits of atemoya amply produced from a fruit-thinning process is normally regarded as waste and discarded. This research aimed at studying antimicrobial, antioxidant, and anti-inflammatory activities of the essential oil (EO) isolated from the immature fruits to explore its potential application. The fruits were subjected to different drying methods: solar drying (SD), oven drying at 30°C (OD-30), and at 50°C (OD-50). The oven drying method gave a higher EO yield than the solar drying method. Spathulenol was the largest compound in the EO after the drying process. Antimicrobial effect was not affected by the different drying methods. Antioxidant activity of the EO was measured by DPPH, nitric oxide, and reducing power methods. The EOOD-50 exhibited a stronger antioxidant activity than EOSD and EOOD-30. The EO also showed an anti-inflammatory activity in a cell model.

  12. Sol gel-fluorination synthesis of amorphous magnesium fluoride

    NASA Astrophysics Data System (ADS)

    Krishna Murthy, J.; Groß, Udo; Rüdiger, Stephan; Kemnitz, Erhard; Winfield, John M.

    2006-03-01

    The sol-gel fluorination process is discussed for the reaction of magnesium alkoxides with HF in non-aqueous solvents to give X-ray amorphous nano-sized magnesium fluoride with high surface areas in the range of 150-350 m 2/g (HS-MgF 2). The H2 type hysteresis of nitrogen adsorption-desorption BET-isotherms is indicative for mesoporous solids. A highly distorted structure causes quite high Lewis acidity, shown by NH 3 temperature-programmed desorption (NH 3-TPD) and catalytic test reactions. XPS data of amorphous and conventionally crystalline MgF 2 are compared, both show octahedral coordination at the metal site. Thermal analysis, F-MAS NMR- and IR-spectroscopy give information on composition and structure of the precursor intermediate as well as of the final metal fluoride. The preparation of complex fluorides, M +MgF 3-, by the sol-gel route is reported. From the magnesium fluoride gel of the above process thin films for optical application are obtained by, e.g., spin coating.

  13. 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.

  14. 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.

  15. Generation and detection of metal ions and volatile organic compounds (VOCs) emissions from the pretreatment processes for recycling spent lithium-ion batteries.

    PubMed

    Li, Jia; Wang, Guangxu; Xu, Zhenming

    2016-06-01

    The recycling of spent lithium-ion batteries brings benefits to both economic and environmental terms, but it can also lead to contaminants in a workshop environment. This study focused on metals, non-metals and volatile organic compounds generated by the discharging and dismantling pretreatment processes which are prerequisite for recycling spent lithium-ion batteries. After discharging in NaCl solution, metal contents in supernate and concentrated liquor were detected. Among results of condition #2, #3, #4 and #5, supernate and concentrated liquor contain high levels of Na, Al, Fe; middle levels of Co, Li, Cu, Ca, Zn; and low levels of Mn, Sn, Cr, Zn, Ba, K, Mg, V. The Hg, Ag, Cr and V are not detected in any of the analyzed supernate. 10wt% NaCl solution was a better discharging condition for high discharge efficiency, less possible harm to environment. To collect the gas released from dismantled LIB belts, a set of gas collecting system devices was designed independently. Two predominant organic vapour compounds were dimethyl carbonate (4.298mgh(-1)) and tert-amylbenzene (0.749mgh(-1)) from one dismantled battery cell. To make sure the concentrations of dimethyl carbonate under recommended industrial exposure limit (REL) of 100mgL(-1), for a workshop on dismantling capacity of 1000kg spent LIBs, the minimum flow rate of ventilating pump should be 235.16m(3)h(-1).

  16. A Retrospective: Active Volatile-Driven Geologic Processes Across the Solar System—Lessons for Planetary Explorers

    NASA Astrophysics Data System (ADS)

    Soderblom, L. A.

    2014-12-01

    When Voyagers 1 and 2 left Earth in 1977, we had little clue as to the rich variety of activity we'd find on the outer Solar System moons. The moons of Jupiter, Saturn, Uranus, and Neptune would likely exhibit little geologic evolution¾much less even than our Moon. We expected battered, cratered, dead worlds. Like the Moon, Mars had showed volcanic activity in the geologic past, but ancient, heavily crater highlands dominated both surfaces. It seemed unlikely that we'd find even extinct volcanism in the cold, dead reaches of the outer Solar System. Voyager 1 shocked us by revealing Io's prolific ongoing volcanism. (Not all were surprised: just days earlier, Peale, Cassen, and Reynolds published a prediction that Io could be volcanically active). Europa, too, was a Voyager surprise; only a small handful of impact craters pocked its surface. It too had to be a geologically young body—likely still actively evolving. We have even found very recent geological activity on tiny cometary nuclei, where young flows have oozed forth across their surfaces. At Neptune, incredibly, Voyager 2 found eruptions on Triton's 37K polar cap—plumes driven by solar-heated nitrogen gas blasting dark dust and bright ice in 8-km-high columns. On Mars, "dark spiders" near the pole signaled similar active eruptions, in this case driven by pressurized carbon dioxide. Cassini witnessed a myriad of jets near tiny Enceladus' south pole, arising from an internal ocean evidently driven by active chemical processes and modulated by Saturn's proximity. Cassini revealed Titan to be Earth's alien twin, with a host of processes borrowed from textbooks on terrestrial geomorphology and meteorology. Akin to Earth's global hydrological cycle, Titan's runs on methane—methane rivers, seas, and rain abound. What lessons can we take from these active places into the next phase of exploration? When the Voyagers were launched, our naiveté allowed that only planet Earth was dynamically active. But exploring

  17. Influence of the process, season, and origin on volatile composition and antioxidant activity of Juniperus phoenicea L. leaves essential oils.

    PubMed

    Ennajar, Monia; Afloulous, Samia; Romdhane, Mehrez; Ibrahim, Hany; Cazaux, Sylvie; Abderraba, Manef; Raies, Aly; Bouajila, Jalloul

    2011-03-01

    Essential oils of Juniperus phoenicea L. leaves cultivated in 3 regions, Korbos, Matmata, and Tabarka of Tunisia were obtained by hydrodistillation (HD), steam distillation (SD), and Soxhlet (SH) extraction methods. The essential oils were analyzed and quantified by capillary gas chromatography using flame ionization detection (GC-FID) and mass spectrometry (GC-MS). The highest yield was observed in HD process (1.12%). Tabarka essential oil provided the best yield 0.79% compared to other regions. December month SD essential oil was the highest in oxygenated monoterpenes (52.7%). Nevertheless, SH essential oil showed a higher content in sesquitepenes hydrocarbons (64.5%). α-Terpinol (25.5%) was the main oxygenated component in Matmata juniper essential oil, extracted by SD. Moreover, the antioxidant activity of essential oils was evaluated using ABTS assays. The strongest antioxidant activity (IC(50) = 22.6 ± 0.7 mg/L) was obtained by the Matmata (October 2007) SD essential oil.

  18. Regional biogenic emissions of reactive volatile organic compounds (BVOC) from forests: First results on process studies, modelling and validation experiments (BEWA2000)

    NASA Astrophysics Data System (ADS)

    Rappenglück, B.; Bewa2000 Team

    2003-04-01

    The overall objective of the research consortia is to develop for a forest canopy a prognostic, validated emission model for primary and secondary volatile organic compounds (VOC) to be used for estimating regional biogenic emissions with a higher spatial and temporal resolution than present. To achieve this objective requires a better description of biosynthetic processes as well as chemical degradation mechanisms for reactive biogenic VOC in combination with a process-based model and latest vegetation specific land use information. Up to now several highlights were achieved within the different key activities. In the section model development a process-based isoprenoid emission model was supplemented with new differential equations especially taking into account the influence of transport-resistances for leaf gas-exchange. In biochemical process-studies related to the formation of isoprene in leaves it turned out that during daytime about 20-70% of the total carbon delivered to poplar leaves (photosynthesis + other sources) was derived from xylem-transported sugars. This finding indicates that xylem-delivered carbon may indeed act as a significant alternative carbon source for isoprenoid biosynthesis. First chemical process studies on the reaction of limonene with NO3 radicals (observed in the night and under low light conditions) in the EUPHORE (European Photoreactor) demonstrated a secondary particle formation. At the field site Waldstein (Fichtelgebirge) this reaction may result in maximum pinonealdhyde concentrations in the air and on particles observed in night periods. A first analysis of particle size distributions over the Norway spruce canopy showed the appearance of small particles (< 10nm) during early daytime. The first results demonstrate that the proposed approach of combining interdisciplinary field, laboratory and modelling exercises to address the complexity of the biosphere/atmosphere exchange of reactive trace gases will contribute

  19. Conference on Planetary Volatiles

    NASA Technical Reports Server (NTRS)

    Pepin, R. O. (Compiler); Oconnell, R. (Compiler)

    1982-01-01

    Initial and present volatile inventories and distributions in the Earth, other planets, meteorites, and comets; observational evidence on the time history of volatile transfer among reservoirs; and volatiles in planetary bodies, their mechanisms of transport, and their relation to thermal, chemical, geological and biological evolution are addressed.

  20. Conference on Planetary Volatiles

    NASA Technical Reports Server (NTRS)

    Hrametz, K.; Kofler, L.

    1982-01-01

    Initial and present volatile inventories and distributions in the Earth, other planets, meteorites, and comets; observational evidence on the time history of volatile transfer among reservoirs; and volatiles in planetary bodies, their mechanisms of transport, and their relation to thermal, chemical, geological and biological evolution were addressed.

  1. The effects of fluoride on cell migration, cell proliferation, and cell metabolism in GH4C1 pituitary tumour cells.

    PubMed

    Mendoza-Schulz, A; Solano-Agama, C; Arreola-Mendoza, L; Reyes-Márquez, B; Barbier, O; Del Razo, L M; Mendoza-Garrido, M E

    2009-10-28

    The consumption of drinking water rich in fluoride has toxic effects on the central nervous system. In cell biology research, fluoride is currently used as a phosphatase inhibitor. The aim of the present study was to evaluate the effect of fluoride on different physiological processes in GH4C1 pituitary tumour cells. We used a range of different fluoride concentrations, from levels below normal human serum concentrations (0.23 and 1.2 micromol/L) to those observed in chronically exposed persons (10.7 micromol/L) and above (107 and 1072 micromol/L). Treatment of 10.7 micromol/L fluoride resulted in a discrete induction of DNA synthesis, without a change in cell number. Cell migration, a behaviour stimulated by growth factors, was increased in cells treated with 2.4 micromol/L. At this fluoride concentration, changes in phosphorylation status of both cytoskeletal and cytosolic protein fractions, as well as in actin cytoskeletal arrangements were observed. The GH4C1 fluoride treated cells had significantly less cellular protein than control cells, suggesting an effect of fluoride on hormone secretion and protein synthesis in this endocrine cell. The bioreduction of MTT was significantly increased with a wide range of fluoride concentrations. With the highest fluoride concentration, 1072 micromol/L, all of the analysed parameters were significantly reduced, suggesting that this dose is highly toxic in GH4C1 cells. Our results show that biologically relevant concentrations of fluoride are capable of increasing cell migration in tumour cells, suggesting that exposure to fluoride could stimulate tumour invasion.

  2. Surface and interfacial effect of filler particle on electrical properties of polyvinyledene fluoride/nickel composites

    NASA Astrophysics Data System (ADS)

    Panda, Maheswar; Srinivas, V.; Thakur, A. K.

    2008-12-01

    The effect of processing conditions and filler particle size/surface area on the dielectric behavior of polyvinyledene fluoride/nickel composites is reported. Large enhancement of low frequency dielectric constant with reduction in metal particle size in a metal-polymer composite is observed. Enhancement in the dielectric constant has been attributed to increase in interfacial area and consequent interfacial polarization with reduction in metal particle size. The increased interparticle contacts from the nearest neighbors result in enhanced tunneling probability leading to lowering of percolation threshold for nanosized nickel/polyvinyledene fluoride composites as compared to micron nickel/polyvinyledene fluoride composites.

  3. 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.

  4. 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.

  5. Optimizing School-Based Health-Promotion Programmes: Lessons from a Qualitative Study of Fluoridated Milk Schemes in the UK

    ERIC Educational Resources Information Center

    Foster, Geraldine R. K.; Tickle, Martin

    2013-01-01

    Background and objective: Some districts in the United Kingdom (UK), where the level of child dental caries is high and water fluoridation has not been possible, implement school-based fluoridated milk (FM) schemes. However, process variables, such as consent to drink FM and loss of children as they mature, impede the effectiveness of these…

  6. Factors affecting the bioaccessibility of fluoride from seafood products.

    PubMed

    Rocha, R A; de la Fuente, B; Clemente, M J; Ruiz, A; Vélez, D; Devesa, V

    2013-09-01

    Fluoride is considered important for health because of its beneficial effect on the prevention of dental caries and on bone development in the child population. However, excessive intake has negative effects. The main pathway for exposure is oral, through consumption of drinking water, and some food products. Therefore its bioaccessibility (quantity of the element solubilized during the digestive process) is a parameter to be considered when estimating the risk/benefit associated with this element. The aim of the present study was to evaluate the influence of the digestion phase, gastrointestinal digestion factors (pH, pepsin and bile salt concentrations) and the presence of cations on the bioaccessibility of fluoride from seafood products. The results show that the solubilization of fluoride takes place entirely during the gastric phase. Its bioaccessibility is strongly influenced by conditions that favor the formation of insoluble complexes of fluoride with other elements present in the matrix. The factors that are most influential in reducing its bioaccessibility are the increase in pH in the gastric phase, the presence of cations, especially in the intestinal phase, and a low concentration of bile salts.

  7. Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

    NASA Technical Reports Server (NTRS)

    West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

    2007-01-01

    We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

  8. Securing non-volatile memory regions

    DOEpatents

    Faraboschi, Paolo; Ranganathan, Parthasarathy; Muralimanohar, Naveen

    2013-08-20

    Methods, apparatus and articles of manufacture to secure non-volatile memory regions are disclosed. An example method disclosed herein comprises associating a first key pair and a second key pair different than the first key pair with a process, using the first key pair to secure a first region of a non-volatile memory for the process, and using the second key pair to secure a second region of the non-volatile memory for the same process, the second region being different than the first region.

  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. 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

  13. 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.

  14. Radiotracer study of the preparation of high-purity lanthanum fluoride

    SciTech Connect

    Ewing, K.J.; Jaganathan, J.; Peitersen, L.; Aggarwal, I.D. ); Sommers, J.A.; Fahey, J.V. )

    1992-06-01

    This paper reports that the behavior of the impurities iron, cobalt, yttrium, and cerium is determined via radiotracer techniques for the preparation of high-purity lanthanum fluoride. The behavior of nickel and copper during the coprecipitation of a lanthanum nitrate solution is determined by graphite furnace atomic absorption spectrometric (GFAAS) analysis. There is no commercially available radiotracer for neodymium, a key impurity associated with absorption losses in fluoride glasses. However, the chemical behavior of neodymium and that of yttrium are very similar and, therefore, it is reasonable to assume that the behavior of yttrium throughout the processing is indicative of the behavior of neodymium. The concentrations of impurities in lanthanum nitrate, carbonate, and fluoride are estimated using the radiotracer and GFAAS data for each processing step. Results indicate that while high-purity lanthanum carbonate can be prepared, any impurities present in the lanthanum carbonate will be carried quantitatively into lanthanum fluoride upon hydrofluorination.

  15. 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.

  16. PREPARATION OF ANHYDROUS F-18 FLUORIDE, T. Tewson. Journal of Labelled Compounds and Radiopharmaceuticals S165; 52, Supplement 1 2009

    SciTech Connect

    Tewson, T.

    2009-07-01

    The original specific aims of the grant where cut back considerably as the study section reduced both the time and the budget for the project. The objective of the grant was to show that fluorine-18 fluoride could be prepared completely anhydrous and thus substantially more reactive than conventionally dried fluoride using the method of Sun and DiMagno. This method involved using conventionally dried fluoride to prepare an aromatic fluoride in which the aromatic ring is substituted with electron withdrawing groups. The aryl fluoride is then dried and purified and the fluoride is displaced with an anhydrous nucleophile. Using fluorine-19 and macroscopic scale reactions the reactions work well and give anhydrous fluoride salts that are both more reactive and more selective in their reactions than conventionally dried fluoride. The original substrate chosen for the reaction was bromopentacyanobenzene (1). This compound proved to be easy to make but very hard to purify. As an alternative hexabromobenzene, which is commercially available in high purity, was tried. This reacted cleanly with conventionally dried F-18 fluoride in acetonitrile to give [{sup 18}F]-fluoropentabromobenzene (2), which could be dried by passage of the solution over alumina, which also removed any unreacted fluoride. The fluorine-18 fluoride could be liberated from (2) by displacement with an anhydrous nucleophilic tetra-alkylammonium salt but the anion had to be chosen with considerable care. The reaction is potentially reversible especially as, on the no carrier added scale, there is inevitably an excess of hexabromobenzene and so the displacing nucleophile is chosen to deactivate the aromatic compound to further nucleophilic displacement reactions. To this end tetrabutylammonium azide and tetrabutylammonium phenolate have been tried. Both work but the phenolate is probably the better choice. The F-18 fluoride produced by this process is substantially more reactive than conventionally dried

  17. [Distribution of fluoride in the combustion products of coal].

    PubMed

    Liu, Jianzhong; Qi, Qingjie; Zhou, Junhu; Cao, Xinyu; Cen, Kefa

    2003-07-01

    The static distribution characteristic of fluoride in the combustion products of coal was studied by ashing procedure of coal, and the dynamic distribution characteristics of fluorine in the combustion products of coal in pulverized-coal-fired boiler and layer-burning boiler were investigated. Experimental results identified that fluorine in coal belong to volatile elements, fluorine in fly ash and bottom ash were non-rich. About 94.5% of the fluorine in coal emitted as gaseous-fluorine during coal combustion in pulverized-coal-fired boiler, and about 80% of the fluorine in coal emitted as gaseous-fluorine during coal combustion in layer-burning boiler. 55%-60% of the fluorine in fly ash of pulverized-coal-fired boiler were distributed in fly ash particles with a diameter of 74 microns-104 microns.

  18. Fluoride accumulation and bone strength in wild black-crowned night-herons

    USGS Publications Warehouse

    Henny, C.J.; Burke, P.M.

    1990-01-01

    Fluoride was measured in femurs of black-crowned night-herons (Nycticorax nycticorax) living adjacent to a phosphate processing complex near Pocatello, Idaho. Fluoride (ash wt.) in femurs ranged from 540 micrograms/g to 11,000 micrograms/g and increased (P = 0.0001) with age, but with no difference (P = 0.80) between sexes. Adult males (greater than or equal to 4 years) contained 5,409 micrograms/g compared to 6,042 micrograms/g for adult females. The tibiotarsus (= tibiae in text) increased in diameter with age (P = 0.015) in this study; fluoride was nearly related (P = 0.065) to the increase. As the diameter increased with age, wall thickness decreased (P = 0.011) suggesting excessive internal bone resorption, but fluoride concentrations were not implicated in the relationship (p = 0.64). The apparent increase in diameter and decrease in wall thickness may have partially neutralized each other's effects on strength. Although significantly higher concentrations of fluoride were present in adults than in Third Year herons, no significant change in bone strength (maximum load or modulus of rupture) was detected between the two age classes, but three of the four comparisons showed adults with less strength (i.e., a hint of diminished strength with age). The tibiae of Hatch Year birds were significantly weaker than documented in older age classes, but incomplete growth was thought responsible. The strong relationship between age and fluoride concentrations reduced our ability to separate a 'fluoride effect' from an 'age effect.' Other authors believed fluoride was responsible for an increase in bone diameter and the fluoride residues encountered in adults were within the range indicative of poisoning in cattle.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Fluoride accumulation and bone strength in wild black-crowned night-herons.

    PubMed

    Henny, C J; Burke, P M

    1990-01-01

    Fluoride was measured in femurs of black-crowned night-herons (Nycticorax nycticorax) living adjacent to a phosphate processing complex near Pocatello, Idaho. Fluoride (ash wt.) in femurs ranged from 540 micrograms/g to 11,000 micrograms/g and increased (P = 0.0001) with age, but with no difference (P = 0.80) between sexes. Adult males (greater than or equal to 4 years) contained 5,409 micrograms/g compared to 6,042 micrograms/g for adult females. The tibiotarsus (= tibiae in text) increased in diameter with age (P = 0.015) in this study; fluoride was nearly related (P = 0.065) to the increase. As the diameter increased with age, wall thickness decreased (P = 0.011) suggesting excessive internal bone resorption, but fluoride concentrations were not implicated in the relationship (p = 0.64). The apparent increase in diameter and decrease in wall thickness may have partially neutralized each other's effects on strength. Although significantly higher concentrations of fluoride were present in adults than in Third Year herons, no significant change in bone strength (maximum load or modulus of rupture) was detected between the two age classes, but three of the four comparisons showed adults with less strength (i.e., a hint of diminished strength with age). The tibiae of Hatch Year birds were significantly weaker than documented in older age classes, but incomplete growth was thought responsible. The strong relationship between age and fluoride concentrations reduced our ability to separate a "fluoride effect" from an "age effect." Other authors believed fluoride was responsible for an increase in bone diameter and the fluoride residues encountered in adults were within the range indicative of poisoning in cattle.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Polymorphism Control of Poly(vinylidene fluoride)

    NASA Astrophysics Data System (ADS)

    Zheng, Jianfen; He, Aihua; Li, Junxing; Han, Charles C.

    2008-03-01

    Poly(vinylidene fluoride) (PVDF) is well-known for its polymorphism, and can exhibit five different polymorphs depending on its processing conditions. The α-phase is the most common and stable polymorph and the β-phase is the most important one due to its piezoelectric and pyroelectric properties. Polymorphism control of PVDF has been realized through electrospinning. PVDF fibrous membranes with fiber diameter in the range of 100 nm to several micrometers were produced by electrospinning and the crystal phase of electrospun PVDF fibers can be adjusted at the same time. Through the control of electrospinning parameters such as the solvent and electrospinning temperature, PVDF fibrous membranes containing mainly α- or β- or γ-phase could be fabricated successfully.

  1. High dielectric permittivity and improved mechanical and thermal properties of poly(vinylidene fluoride) composites with low carbon nanotube content: effect of composite processing on phase behavior and dielectric properties

    NASA Astrophysics Data System (ADS)

    Sudheer Kumar, G.; Vishnupriya, D.; Chary, K. Suresh; Umasankar Patro, T.

    2016-09-01

    The composite processing technique and nanofiller concentration and its functionalization significantly alter the properties of polymer nanocomposites. To realize this, multi-walled carbon nanotubes (CNT) were dispersed in a poly(vinylidene fluoride) (PVDF) matrix at carefully selected CNT concentrations by two illustrious methods, such as solution-cast and melt-mixing. Notwithstanding the processing method, CNTs induced predominantly the γ-phase in PVDF, instead of the commonly obtained β-phase upon nanofiller incorporation, and imparted significant improvements in dielectric properties. Acid-treatment of CNT improved its dispersion and interfacial adhesion significantly with PVDF, and induced a higher γ-phase content and better dielectric properties in PVDF as compared to pristine CNT. Further, the γ-phase content was found to be higher in solution-cast composites than that in melt-mixed counterparts, most likely due to solvent-induced crystallization in a controlled environment and slow solvent evaporation in the former case. However, interestingly, the melt-mixed composites showed a significantly higher dielectric constant at the onset of the CNT networked-structure as compared to the solution-cast composites. This suggests the possible role of CNT breakage during melt-mixing, which might lead to higher space-charge polarization at the polymer-CNT interface, and in turn an increased number of pseudo-microcapacitors in these composites than the solution-cast counterparts. Notably, PVDF with 0.13 vol% (volume fraction, f c = 0.0013) of acid-treated CNTs, prepared by melt-mixing, displayed the relative permittivity of ˜217 and capacitance of ˜5430 pF, loss tangent of ˜0.4 at 1 kHz and an unprecedented figure of merit of ˜105. We suggest a simple hypothesis for the γ-phase formation and evolution of the high dielectric constant in these composites. Further, the high-dielectric composite film showed marked improvements in mechanical and thermal properties

  2. 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

  3. 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

  4. Dentifrice fluoride and abrasivity interplay on artificial caries lesions.

    PubMed

    Nassar, Hani M; Lippert, Frank; Eckert, George J; Hara, Anderson T

    2014-01-01

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

  5. 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.

  6. Chlorine and fluorine partition coefficients and abundances in sub-arc mantle xenoliths (Kamchatka, Russia): Implications for melt generation and volatile recycling processes in subduction zones

    NASA Astrophysics Data System (ADS)

    Bénard, A.; Koga, K. T.; Shimizu, N.; Kendrick, M. A.; Ionov, D. A.; Nebel, O.; Arculus, R. J.

    2017-02-01

    We report chlorine (Cl) and fluorine (F) abundances in minerals, interstitial glasses, and melt inclusions in 12 andesite-hosted, spinel harzburgite xenoliths and crosscutting pyroxenite veins exhumed from the sub-arc lithospheric mantle beneath Avacha volcano in the Kamchatka Arc (NE Russia). The data are used to calculate equilibrium mineral-melt partition coefficients (D mineral / melt) for Cl and F relevant to subduction-zone processes and unravel the history of volatile depletion and enrichment mechanisms in an arc setting. Chlorine is ∼100 times more incompatible in pyroxenes (DClmineral/melt = 0.005-0.008 [±0.002-0.003]) than F (DFmineral/melt = 0.50-0.57 [±0.21-0.24]), which indicates that partial melting of mantle sources leads to strong depletions in Cl relative to F in the residues. The data set in this study suggests a strong control of melt composition on DCl,Fpyroxene/melt, in particular H2O contents and Al/(Al + Si), which is in line with recent experiments. Fluorine is compatible in Ca-amphibole in the 'wet' sub-arc mantle (DFamphibole/melt = 3.5-3.7 [±1.5]) but not Cl (DClamphibole/melt = 0.03-0.05 [±0.01-0.03]), indicating that amphibole may fractionate F from Cl in the mantle wedge. The inter-mineral partition coefficients for Cl and F in this study are consistent amongst different harzburgite samples, whether they contain glass or not. In particular, disseminated amphibole hosts much of the Cl and F bulk rock budgets of spinel harzburgites (DClamphibole/pyroxene up to 14 and DFamphibole/pyroxene up to 40). Chlorine and fluorine are variably enriched (up to 1500 ppm Cl and 750 ppm F) in the parental arc picrite and boninite melts of primitive pyroxenite veins (and related melt inclusions) crosscutting spinel harzburgites.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. [18F]fluorination/decarbonylation: new route to aryl [18F]fluorides.

    PubMed

    Chakraborty, P K; Kilbourn, M R

    1991-01-01

    A new route to aryl [18F]fluorides without electron withdrawing ring substituents has been developed. [18F]Fluorobenzaldehydes, prepared from no-carrier-added (NCA) [18F]fluoride using nucleophilic aromatic substitution of fluoro or nitro groups, were decarbonylated using palladium on charcoal (Pd-C). By this approach 2-methoxy-4-nitrobenzaldehyde was converted to NCA 3-[18F]fluorophenol (25-30%, EOB) and 4-fluoro-2-methoxy-5-methylbenzaldehyde to carrier-added (CA) 3-[18F]fluoro-4-methylphenol (30-40%, EOB). Overall synthesis time was about 2 h. Since the 4-fluoro-2-methoxy-5-methylbenzaldehyde was in turn prepared by methylation and regiospecific formylation of 3-fluoro-4-methylphenol, the overall process represents use of a removable activating group for nucleophilic aromatic substitution with [18F]fluoride for preparation of CA and NCA aryl [18F]fluorides.

  20. Inhibition of Aspergillus niger phosphate solubilization by fluoride released from rock phosphate.

    PubMed

    Mendes, Gilberto de Oliveira; Vassilev, Nikolay Bojkov; Bonduki, Victor Hugo Araújo; da Silva, Ivo Ribeiro; Ribeiro, José Ivo; Costa, Maurício Dutra

    2013-08-01

    The simultaneous release of various chemical elements with inhibitory potential for phosphate solubilization from rock phosphate (RP) was studied in this work. Al, B, Ba, Ca, F, Fe, Mn, Mo, Na, Ni, Pb, Rb, Si, Sr, V, Zn, and Zr were released concomitantly with P during the solubilization of Araxá RP (Brazil), but only F showed inhibitory effects on the process at the concentrations detected in the growth medium. Besides P solubilization, fluoride decreased fungal growth, citric acid production, and medium acidification by Aspergillus niger. At the maximum concentration found during Araxá RP solubilization (22.9 mg F(-) per liter), fluoride decreased P solubilization by 55%. These findings show that fluoride negatively affects RP solubilization by A. niger through its inhibitory action on the fungal metabolism. Given that fluoride is a common component of RPs, the data presented here suggest that most of the microbial RP solubilization systems studied so far were probably operated under suboptimal conditions.

  1. The physical and chemical characteristics of particles in indoor air where high fluoride coal burning takes place

    SciTech Connect

    Gu, S.L.; Ji, R.D.; Cao, S.R. )

    1990-12-01

    In China, more than 10 million people suffer from fluorosis caused by the burning of high fluoride coal. Analysis of the particulate matters of indoor air from these fluorosis areas reveals a logarithmic distribution of particle sizes. The levels of F- and SO4(2-) adsorbed or absorbed on the particles ranged from 16.27 to 46.18 micrograms/m3 and from 244.7 to 374.6 micrograms/m3, respectively. Gaseous and soluble fluorides constituted a considerable proportion of the inorganic fluorides. Nevertheless, the level of F- in air was considered to be inadequate to cause the observed severity of fluorosis. It is speculated that additional intake of F- from contaminated foods might also be a major factor contributing to the fluorosis. Additionally, some volatile elements (e.g., sulfur and its derivatives) might have some relation to fluorosis of this type.

  2. Food price volatility

    PubMed Central

    Gilbert, C. L.; Morgan, C. W.

    2010-01-01

    The high food prices experienced over recent years have led to the widespread view that food price volatility has increased. However, volatility has generally been lower over the two most recent decades than previously. Variability over the most recent period has been high but, with the important exception of rice, not out of line with historical experience. There is weak evidence that grains price volatility more generally may be increasing but it is too early to say. PMID:20713400

  3. Method of making carbide/fluoride/silver composites

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor); Dellacorte, Christopher (Inventor)

    1991-01-01

    A composition containing 30 to 70 percent chromium carbide, 5 to 20 percent soft noble metal, 5 to 20 percent metal fluorides, and 20 to 60 percent metal binder is used in a powdered metallurgy process for the production of self-lubricating components, such as bearings. The use of the material allows the self-lubricating bearing to maintain its low friction properties over an extended range of operating temperatures.

  4. Iodine volatility. [PWR; BWR

    SciTech Connect

    Beahm, E.C.; Shockley, W.E.

    1984-01-01

    The ultimate aim of this program is to couple experimental aqueous iodine volatilities to a fission product release model. Iodine partition coefficients, for inorganic iodine, have been measured during hydrolysis and radiolysis. The hydrolysis experiments have illustrated the importance of reaction time on iodine volatility. However, radiolysis effects can override hydrolysis in determining iodine volatility. In addition, silver metal in radiolysis samples can react to form silver iodide accompanied by a decrease in iodine volatility. Experimental data are now being coupled to an iodine transport and release model that was developed in the Federal Republic of Germany.

  5. 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.

  6. 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.

  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. The Age of Lunar South Circumpolar Craters Haworth, Shoemaker, Faustini, and Shackleton: Implications for Regional Geology, Surface Processes, and Volatile Sequestration

    NASA Technical Reports Server (NTRS)

    Tye, A. R.; Fassett, C. I.; Head, J. W.; Mazarico, E.; Basilevsky, A. T.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2015-01-01

    The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size-frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D greater than or equal to 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D greater than or equal to 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slopedependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have approximately 1-2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have approximately 5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (approximately 3.5 Ga) crater retention ages of their

  13. The age of lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton: Implications for regional geology, surface processes, and volatile sequestration

    NASA Astrophysics Data System (ADS)

    Tye, A. R.; Fassett, C. I.; Head, J. W.; Mazarico, E.; Basilevsky, A. T.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.

    2015-07-01

    The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size-frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D ⩾ 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D ⩾ 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slope-dependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have ∼1-2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have ∼5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (∼3.5 Ga) crater retention ages of their floors suggests that any water ice that might have been deposited in

  14. Water Atomization of Barium Fluoride: Calcium Fluoride for Enhanced Flow Characteristics of PS304 Feedstock Powder Blend

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.; DellaCorte, Christopher

    2003-01-01

    PS304 is a plasma spray deposited solid lubricant coating with feedstock composed of NiCr, Cr2O3, Ag, and BaF2-CaF2 powders. The effects of rounded BaF2-CaF2 particles on the gravity-fed flow characteristics of PS304 feedstock have been investigated. The BaF2-CaF2 powder was fabricated by water atomization using four sets of process parameters. Each of these powders was then characterized by microscopy and classified by screening to obtain 45 to 106 micron particles and added incrementally from 0 to 10 wt% to the other constituents of the PS304 feedstock, namely nichrome, chromia, and silver powders. The relationship between feedstock flow rate, measured with the Hall flowmeter, and concentration of fluorides was found to be linear in each case. The slopes of the lines were between those of the linear relationships previously reported using angular and spherical fluorides and were closer to the relationship predicted using the rule of mixtures. The results offer a fluoride fabrication technique potentially more cost-effective than gas atomization processes or traditional comminution processes.

  15. Calcination process for radioactive wastes

    DOEpatents

    Kilian, Douglas C.

    1976-05-04

    The present invention provides a method for minimizing the volatilization of chlorides during solidification in a fluidized-bed calciner of liquids containing sodium, nitrate and chloride ions. Zirconium and fluoride are introduced into the liquid, and one-half mole of calcium nitrate is added per mole of fluoride present in the liquid mixture. The mixture is calcined in the fluidized-bed calciner at about 500.degree.C., producing a high bulk density calcine product containing the chloride, thus tying up the chloride in the solid product and minimizing chloride volatilization.

  16. Organometallic Chemical Vapor Deposition of ZrF4-Based Fluoride Glasses

    NASA Astrophysics Data System (ADS)

    Fujiura, Kazuo; Ohishi, Yasutake; Takahashi, Shiro

    1989-01-01

    By organometallic chemical vapor deposition (OMCVD), fluoride glasses in a ZrF4-BaF2 binary system are successfully synthesized. β-Diketone chelates of Zr and Ba as starting materials can be volatilized and completely fluorinated with HF gas into ZrF4-BaF2 compounds. 65 mol%ZrF4-35 mol%BaF2 powder synthesized by OMCVD is identified as homogeneous glass by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). By this method, ZrF4 is also obtained in an amorphous state. The OMCVD is available for preparation of fluoride glass, which is promising for optical fiber.

  17. 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.

  18. 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

  19. 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

  20. High performance fluoride optical coatings for DUV optics

    NASA Astrophysics Data System (ADS)

    Zhang, Lichao; Cai, Xikun

    2014-08-01

    In deep ultraviolet region that typical applications are used on the ArF wavelength, coated optics should meet stringent requirements of optical systems. To meet these requirements, systematical researches are carried out on fabrication and characterization methods of fluoride coatings. First, by optimizing of deposition processes, dense coatings with the refractive index of ~1.7 for LaF3 and ~1.4 for MgF2, together with extinction coefficients of ~2×10-4 on 193nm were realized. The transmission of AR coating for 193nm achieved by using optimized deposition techniques is 99.8%. Second, a method of designing shadowing masks was developed to solve the problem of correcting coating thickness distributions for complex DUV systems. By using the method, the thickness distribution error specification of 3% PV has been achieved on substrates with ~300mm diameters and large curvatures. Finally, the laser calorimetry method is used to evaluate the laser radiation stability of fluoride coatings. It is turned out that the damage coefficients of fluoride coatings, which are defined as the values of unrecoverable increase of the absorption during the laser irradiation process, are much lower than that of fused silica substrates. The above progresses could further support the realization of high performance DUV optical systems.

  1. 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.

  2. 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...

  3. Pyrolysis and volatilization of cocaine

    SciTech Connect

    Martin, B.R.; Lue, L.P.; Boni, J.P. )

    1989-05-01

    The increasing popularity of inhaling cocaine vapor prompted the present study, to determine cocaine's fate during this process. The free base of (3H)cocaine (1 microCi/50 mg) was added to a glass pipe, which was then heated in a furnace to simulate freebasing. Negative pressure was used to draw the vapor through a series of glass wool, ethanol, acidic, and basic traps. Air flow rate and temperature were found to have profound effects on the volatilization and pyrolysis of cocaine. At a temperature of 260 degrees C and a flow rate of 400 mL/min, 37% of the radioactivity remained in the pipe, 39% was found in the glass wool trap, and less than 1% in the remainder of the volatilization apparatus after a 10-min volatilization. Reducing the air flow rate to 100 mL/min reduced the amount of radioactivity collected in the glass wool trap to less than 10% of the starting material and increased the amount that remained in the pipe to 58%. GC/MS analysis of the contents of the glass wool trap after volatilization at 260 degrees C and a flow rate of 400 mL/min revealed that 60% of the cocaine remained intact, while approximately 6 and 2% of the starting material was recovered as benzoic acid and methylecgonidine, respectively. As the temperature was increased to 650 degrees C, benzoic acid and methylecgonidine accounted for 83 and 89% of the starting material, respectively, whereas only 2% of the cocaine remained intact. Quantitation of cocaine in the vapor during the course of volatilization revealed high concentrations during the first two min and low concentrations for the remaining time.

  4. Use of laterite for the removal of fluoride from contaminated drinking water.

    PubMed

    Sarkar, Mitali; Banerjee, Aparna; Pramanick, Partha Pratim; Sarkar, Asit R

    2006-10-15

    The effects of different operational variables on the mechanistic function of laterite in removal of fluoride have been investigated. Thermodynamic parameters such as free energy change, enthalpy, and entropy of the process, as well as the sorption isotherm, were evaluated. The extent of solute removal is determined by initial solute concentration, operational conditions, laterite dose, and solution pH. For a fixed set of experimental conditions, a model equation is developed from which the percent removal corresponding to each load of fluoride is determined. The mechanism of fluoride adsorption is governed by the zero point charge of laterite and follows a first-order rate equation. pH has a vital role influencing the surface characteristics of laterite. To simulate the flow dynamics, fluoride solution was run through a fixed bed column. The pattern of breakthrough curves for different influent fluoride concentration, pH, and column bed height was characterized. The column efficiency was tested from the bed depth-service time model. The elution of the retained fluoride was studied and the effectiveness of column operation was determined by the retention-elution cycles.

  5. Removal of fluoride by hydrous manganese oxide-coated alumina: performance and mechanism.

    PubMed

    Teng, Shao-Xiang; Wang, Shu-Guang; Gong, Wen-Xin; Liu, Xian-Wei; Gao, Bao-Yu

    2009-09-15

    A novel hydrous-manganese-oxide-coated alumina (HMOCA) material was prepared through a redox process. The adsorbent was characterized by SEM, BET surface area measurement, XRD, pH(PZC) measurement, FTIR spectroscopy, and XPS. The manganese oxides were amorphous and manganese existed mainly in the +IV oxidation state. Batch and column experiments were carried out to investigate the adsorption potential of the adsorbent. Fluoride adsorption onto HMOCA followed the pseudo-second-order equation well with a correlation coefficient greater than 0.99. Both external and intraparticle diffusion contributed to the rate of transfer and removal. The adsorption of fluoride was thought to take place mainly by ion-exchange. Optimum removal of fluoride occurred in a pH range of 4.0-6.0. The maximum adsorption capacity calculated from the Langmuir model was 7.09 mg/g. The presence of HCO(3)(-), SO(4)(2-) and PO(4)(3-) had negative effects on the adsorption of fluoride. The adsorbed fluoride can be released by alkali solution. Column studies were performed and 669 bed volumes were treated with the effluent fluoride under 1.0mg/L at an influent F(-) concentration of 5.0mg/L and flow rate of 2.39 m(3)/(m(2)h) (empty bed contact time=7.5 min).

  6. 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 ...

  7. 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

  8. Characterization and adsorption properties of a lanthanum-loaded magnetic cationic hydrogel composite for fluoride removal.

    PubMed

    Dong, Shuoxun; Wang, Yili

    2016-01-01

    In this study, a novel lanthanum-loaded magnetic cationic hydrogel (MCH-La) was synthesized for fluoride adsorption from drinking water. The adsorption kinetics, isotherms, and effects of pH and co-existing anions on fluoride uptake by MCH-La were evaluated. FTIR, Raman and XPS were used to analyze the fluoride adsorption mechanism of MCH-La. Results showed that MCH-La had positive zeta potential values of 23.6-8.0 mV at pH 3.0-11.0, with the magnitude of saturation magnetization up to 10.3 emu/g. The fluoride adsorption kinetics by MCH-La fitted well with the fractal-like-pseudo-second-order model, and the adsorption capacity reached 93% of the ultimate adsorption capacity within the first 10 min. The maximum fluoride adsorption capacity for MCH-La was 136.78 mg F(-)/g at an equilibrium fluoride concentration of 29.3 mg/L and pH 7.0. Equilibrium adsorption data showed that the Sips model was more suitable than the Langmuir and Freundlich models. MCH-La still had more than 100 mg of F(-)/g adsorption capacity at a strongly alkaline solution (pH > 10). The adsorption process was highly pH-dependent, and the optimal adsorption was attained at pH 2.8-4.0, corresponding to ligand exchange, electrostatic interactions, and Lewis acid-base interactions. With the exception of both anions of HCO3(-) and SiO4(4-), Cl(-), NO3(-), and SO4(2-) did not evidently prevent fluoride removal by MCH-La at their real concentrations in natural groundwater. The fluoride adsorption capacity of the regenerated MCH-La approached 70% of the fresh MCH-La from the second to fifth recycles. FTIR and Raman spectra revealed that C-O and CO functional groups on MCH contributed to the fluoride adsorption, this finding was also confirmed by the XPS F 1s spectra. Deconvolution of C 1s spectra before and after fluoride adsorption indicated that the carboxyl, anhydride, and phenol groups of MCH were involved in the fluoride removal.

  9. 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.

  10. Sulfate-doped Fe3O4/Al2O3 nanoparticles as a novel adsorbent for fluoride removal from drinking water.

    PubMed

    Chai, Liyuan; Wang, Yunyan; Zhao, Na; Yang, Weichun; You, Xiangyu

    2013-08-01

    A novel adsorbent of sulfate-doped Fe3O4/Al2O3 nanoparticles with magnetic separability was developed for fluoride removal from drinking water. The nanosized adsorbent was characterized and its performance in fluoride removal was evaluated. Kinetic data reveal that the fluoride adsorption was rapid in the beginning followed by a slower adsorption process, nearly 90% adsorption can be achieved within 20 min and only 10-15% additional removal occurred in the following 8 h. The fluoride adsorption isotherm was well described by Elovich model. The calculated adsorption capacity of this nanoadsorbent for fluoride by two-site Langmuir model was 70.4 mg/g at pH 7.0. Moreover, this nanoadsorbent performed well over a considerable wide pH range of 4-10, and the fluoride removal efficiencies reached up to 90% and 70% throughout the pH range of 4-10 with initial fluoride concentrations of 10 mg/L and 50 mg/L, respectively. The observed sulfate-fluoride displacement and decreased sulfur content on the adsorbent surface reveal that anion exchange process was an important mechanism for fluoride adsorption by the sulfate-doped Fe3O4/Al2O3 nanoparticles. Moreover, a shift of the pH of zero point charge (pHPZC) of the nanoparticles and surface analysis based on X-ray photoelectron spectroscopy (XPS) suggest the formation of inner-sphere fluoride complex at the aluminum center as another adsorption mechanism. With the exception of PO4(3-), other co-existing anions (NO3(-), Cl(-) and SO4(2-)) did not evidently inhibit fluoride removal by the nanoparticles. Findings of this study demonstrate the potential utility of the nanoparticles as an effective adsorbent for fluoride removal from drinking water.

  11. Effects of treatment with sodium fluoride and subsequent starvation on fluoride content of earthworms

    SciTech Connect

    Walton, K.C.

    1987-01-01

    The two experiments described here originated during a long-term investigation into the occurrence and movement of pollutant fluoride in a terrestrial ecosystem. Moles (Talpa europaea) whose diet consist largely of various species of earthworm Lumbricidae, are one of the species under investigation. Bone fluoride in moles was found to be higher, on average, than in foxes or small rodents. Moles probably acquire fluoride from their earthworm diet. Earthworms do not have any readily identifiable tissue in which to store large amounts of fluoride but, for their size, they have a considerable amount of soil in their gut, up oto 20% of their dry weight. Preliminary measurements of fluoride in whole earthworms suggested that observed levels could probably be accounted for by fluoride bound in the mineral part of contained soil and released during preparatory ashing. Two experiments to investigate this situation are described; here their aims were: to expose earthworms kept in soil to different concentrations of sodium fluoride; to measure resulting fluoride in earthworms when soil was removed from their gut by starvation for varying periods of time; and to compare amounts of fluoride in whole starved earthworms with those in starved earthworms from which remaining soil had also been physically removed by dissection and washing.

  12. Daily Fluoride Intake from Iranian Green Tea: Evaluation of Various Flavorings on Fluoride Release

    PubMed Central

    Maleki, Afshin; Daraei, Hiua; Mohammadi, Elham; Zandi, Shiva; Teymouri, Pari; Mahvi, Amir Hossien; Gharibi, Fardin

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

  13. Daily Fluoride Intake from Iranian Green Tea: Evaluation of Various Flavorings on Fluoride Release.

    PubMed

    Maleki, Afshin; Daraei, Hiua; Mohammadi, Elham; Zandi, Shiva; Teymouri, Pari; Mahvi, Amir Hossien; Gharibi, Fardin

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P < 0.05). However, the additives had no significant effect on the fluoride release into the infusions (P > 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers.

  14. 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.

  15. 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

  16. 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.

  17. Impact of high hydrostatic pressure on non-volatile and volatile compounds of squid muscles.

    PubMed

    Yue, Jin; Zhang, Yifeng; Jin, Yafang; Deng, Yun; Zhao, Yanyun

    2016-03-01

    The effects of high hydrostatic pressure processing (HHP at 200, 400 or 600MPa) on non-volatile and volatile compounds of squid muscles during 10-day storage at 4°C were investigated. HHP increased the concentrations of Cl(-) and volatile compounds, reduced the level of PO4(3-), but did not affect the contents of 5'-uridine monophosphate (UMP), 5'-guanosine monophosphate (GMP), 5'-inosine monophosphate (IMP), Na(+) and Ca(2+) in squids on Day 0. At 600MPa, squids had the highest levels of 5'-adenosine monophosphate, Cl(-) and lactic acid, but the lowest contents of CMP and volatile compounds on Day 10. Essential free amino acids and succinic acids were lower on Day 0 than on Day 10. HHP at 200MPa caused higher equivalent umami concentration (EUC) on Day 0, and the EUC decreased with increasing pressure on Day 10. Generally, HHP at 200MPa was beneficial for improving EUC and volatile compounds of squids.

  18. Arsenic and fluoride in the groundwater of Mexico.

    PubMed

    Armienta, M A; Segovia, N

    2008-08-01

    Concentrations of arsenic and fluoride above Mexican drinking water standards have been detected in aquifers of various areas of Mexico. This contamination has been found to be mainly caused by natural sources. However, the specific processes releasing these toxic elements into groundwater have been determined in a few zones only. Many studies, focused on arsenic-related health effects, have been performed at Comarca Lagunera in northern México. High concentrations of fluoride in water were also found in this area. The origin of the arsenic there is still controversial. Groundwater in active mining areas has been polluted by both natural and anthropogenic sources. Arsenic-rich minerals contaminate the fractured limestone aquifer at Zimapán, Central México. Tailings and deposits smelter-rich fumes polluted the shallow granular aquifer. Arsenic contamination has also been reported in the San Antonio-El Triunfo mining zone, southern Baja California, and Santa María de la Paz, in San Luis Potosí state. Even in the absence of mining activities, hydrogeochemistry and statistical techniques showed that arsenopyrite oxidation may also contaminate water, as in the case of the Independencia aquifer in the Mexican Altiplano. High concentrations of arsenic have also been detected in geothermal areas like Los Azufres, Los Humeros, and Acoculco. Prevalence of dental fluorosis was revealed by epidemiological studies in Aguascalientes and San Luis Potosí states. Presence of fluoride in water results from dissolution of acid-volcanic rocks. In Mexico, groundwater supplies most drinking water. Current knowledge and the geology of Mexico indicate the need to include arsenic and fluoride determinations in groundwater on a routine basis, and to develop interdisciplinary studies to assess the contaminant's sources in all enriched areas.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Inequalities in public water supply fluoridation in Brazil: An ecological study

    PubMed Central

    Gabardo, Marilisa CL; da Silva, Wander J; Olandoski, Marcia; Moysés, Simone T; Moysés, Samuel J

    2008-01-01

    Background The literature is scarce on the social and geographic inequalities in the access to and implementation of the fluoridation of public water supplies. This study adds knowledge to the Brazilian experience of the chronic privation of water and wastewater policies, access to potable water and fluoridation in the country. Thus, the aim of this study was to verify possible inequalities in the population's access to fluoridated drinking water in 246 Brazilian municipalities. Methods The information on the process of water fluoridation in the municipalities and in the macro region in which each municipality is located was obtained from the national epidemiological survey which was concluded in 2003. The data relating to the human development index at municipal level (HDI-M) and access to mains water came from the Brazilian Human Development Atlas, whilst the size of the population was obtained from a governmental source. The Fisher exact test (P < 0.05) was employed to identify significant associations between the explanatory variables and their ability to predict the principal outcomes of interest to this study, namely the presence or absence of the water fluoridation process in the municipalities as well as the length of time during which this measure has been implemented. Linear regression was used to observe the associations between the relevant variables in a multivariate environment. Results The results clearly showed that there is a relationship between municipalities with larger populations, located in more socio-economically advantaged regions and with better HDI-M, and where fluoridation is both present and has been implemented for a longer period of time (started before 1990). Conclusion The findings suggest that the aim of treating water with fluoride may not be being adequately achieved, requiring more effective strategies so that access to this measure can be expanded equitably. PMID:18402688

  4. Volatile Organic Compounds (VOCs)

    MedlinePlus

    ... United States Environmental Protection Agency Search Search Indoor Air Quality (IAQ) Share Facebook Twitter Google+ Pinterest Contact Us Volatile Organic Compounds' Impact on Indoor Air Quality On this page: Introduction Sources Health Effects Levels ...

  5. 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.

  6. Martian Volatiles and Isotopic Signatures

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    1997-01-01

    Data on martian volatiles gathered from Viking atmosphere measurements, modest groundbased spectra, shock-implanted atmospheric gases in martian (SNC) meteorites, trapped mantle gases in martian meteorites, and volatile-rich solid phases in martian meteorites, are presented. Atmospheric volatiles, surface volatiles, and isotopic chronologies are discussed, along with energetic particle interactions.

  7. 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.

  8. 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.

  9. 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.

  10. Does implied volatility of currency futures option imply volatility of exchange rates?

    NASA Astrophysics Data System (ADS)

    Wang, Alan T.

    2007-02-01

    By investigating currency futures options, this paper provides an alternative economic implication for the result reported by Stein [Overreactions in the options market, Journal of Finance 44 (1989) 1011-1023] that long-maturity options tend to overreact to changes in the implied volatility of short-maturity options. When a GARCH process is assumed for exchange rates, a continuous-time relationship is developed. We provide evidence that implied volatilities may not be the simple average of future expected volatilities. By comparing the term-structure relationship of implied volatilities with the process of the underlying exchange rates, we find that long-maturity options are more consistent with the exchange rates process. In sum, short-maturity options overreact to the dynamics of underlying assets rather than long-maturity options overreacting to short-maturity options.

  11. Influence of storage conditions on the formation of some volatile compounds in white fortified wines (Vins doux naturels) during the aging process.

    PubMed

    Cutzach, I; Chatonnet, P; Dubourdieu, D

    2000-06-01

    Sweet fortified wines, traditionally aged under strong oxidation conditions, have a characteristic aroma. An experimental study investigated the aging of white sweet fortified wines under various conditions. The development of various molecules, previously identified as characteristic of the aroma of this type of wine, was monitored by analysis. The development of these compounds during accelerated aging was affected by oxidation and the color of the wine. Aging in oak containers, variable storage temperatures, and variable modes of oxidation affect the formation of many of the volatile compounds responsible for the aging aroma of vins doux naturels (fortified wines). Furfural (1), 5-ethoxymethylfurfural (2), and sotolon (3) always reach concentrations above their perception thresholds in wood-aged wines, especially when new oak is used. The isomers of methyl-gamma-octalactone (4 and 5) are reliable indicators of aging in oak. Among the many identifiable volatile phenols, only the vanillin (7) content increases with aging, particularly if the container is made of wood and there is a high degree of oxidation. This molecule frequently reaches and even exceeds its perception threshold. We show here that vanillin and isomers of methyl-gamma-octalactone have a major impact on the aromas of fortified wines.

  12. 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.

  13. Unraveling the effect of primary versus secondary processes on the volatile content of MORB glasses: an example from the equatorial Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Le Voyer, M.; Hauri, E. H.; Kelley, K. A.; Cottrell, E.

    2012-12-01

    We report the volatile contents of 20 basaltic glasses from the 1987 cruise of the R/V Robert Conrad to the equatorial Mid-Atlantic Ridge (RC2806, 7°S-5°N). Schilling (pers. comm.) reported that these samples exploded, or "popped," on the deck of the ship, similar to what was reported for the 2πD43 popping rock [1]. We therefore anticipated that they may not have degassed significantly. The goal of this study is to discuss the origin of their volatiles (primary vs. secondary) and the amount of degassing. In terms of major, trace and isotopic compositions [2, 3, 4], the samples are very similar to the other basalts from this location, following the same along-ridge spatial variations, with a strong influence from the Sierra Leone plume at 1.7°N. Unlike 2πD43 (vesicularity of 17-18 vol% [1]), our samples have low vesicularities (< a few vol%, indicating fluid-saturation), more typical of MORBs. They contain 0.32-1.00 wt% H2O, 120-210 ppm CO2, 80-520 ppm F, 770-1200 ppm S and 60-320 ppm Cl dissolved in the glass (determined by SIMS). H2O, F, Cl and S are negatively correlated with MgO, indicating the influence of crystallization. To free ourselves from this effect, we compare each volatile element with a non-volatile trace element with similar incompatibility. First, using the Cl, K and Ti systematics, we determined that at least 4 out of the 20 samples have suffered from seawater-like contamination (assimilation of either pure seawater or an igneous component previously altered by seawater). Second, for the 16 uncontaminated samples, good correlations (R2≥0.9) between Cl and K, F and P, and H2O and Ce, indicate that Cl, F and H2O did not degass significantly. When plotted against the distance along the ridge axis, we find that the F/P (and Cl/K, to a smaller extent) increase with proximity to the Sierra Leone hotspot, and correlate with radiogenic isotopes. Thus these volatile enrichments reflect source variation. When plotted against Nb and Dy, respectively

  14. 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

  15. Role of the P-F bond in fluoride-promoted aqueous VX hydrolysis: an experimental and theoretical study.

    PubMed

    Marciano, Daniele; Columbus, Ishay; Elias, Shlomi; Goldvaser, Michael; Shoshanim, Ofir; Ashkenazi, Nissan; Zafrani, Yossi

    2012-11-16

    Following our ongoing studies on the reactivity of the fluoride ion toward organophosphorus compounds, we established that the extremely toxic and environmentally persistent chemical warfare agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is exclusively and rapidly degraded to the nontoxic product EMPA (ethyl methylphosphonic acid) even in dilute aqueous solutions of fluoride. The unique role of the P-F bond formation in the reaction mechanism was explored using both experimental and computational mechanistic studies. In most cases, the "G-analogue" (O-ethyl methylphosphonofluoridate, Et-G) was observed as an intermediate. Noteworthy and of practical importance is the fact that the toxic side product desethyl-VX, which is formed in substantial quantities during the slow degradation of VX in unbuffered water, is completely avoided in the presence of fluoride. A computational study on a VX-model, O,S-diethyl methylphosphonothioate (1), clarifies the distinctive tendency of aqueous fluoride ions to react with such organophosphorus compounds. The facility of the degradation process even in dilute fluoride solutions is due to the increased reactivity of fluoride, which is caused by the significant low activation barrier for the P-F bond formation. In addition, the unique nucleophilicity of fluoride versus hydroxide toward VX, in contrast to their relative basicity, is discussed. Although the reaction outcomes were similar, much slower reaction rates were observed experimentally for the VX-model (1) in comparison to VX.

  16. Temperature effect on the zeta potential and fluoride adsorption at the alpha-Al2O3/aqueous solution interface.

    PubMed

    López Valdivieso, A; Reyes Bahena, J L; Song, S; Herrera Urbina, R

    2006-06-01

    The effect of temperature and pH on the zeta potential of alpha-Al2O3 and adsorption of fluoride ions at the alpha-Al2O3/aqueous solution interface has been investigated through electrophoretic mobility measurements and adsorption studies, to delineate mechanisms involved in the removal of fluoride ions from water using alumina as adsorbent. When the temperature increases from 10 to 40 degrees C, the pH of the point of zero charge (pH(pzc)) shifts to smaller values, indicating proton desorption from the alumina surface. The pH(pzc) increases linearly with 1/T, which allowed estimation of the standard enthalpy change for the surface-deprotonation process. Fluoride ion adsorption follows a Langmuir-type adsorption isotherm and is affected by the electric charge at the alpha-Al2O3/aqueous solution interface and the surface density of hydroxyl groups. Such adsorption occurs through an exchange between fluoride ions and surface-hydroxyl groups and it depends on temperature, pH, and initial fluoride ion concentration. At 25 and 40 degrees C, maximum fluoride adsorption density takes place between pH 5 and 6. Increasing the temperature from 25 to 40 degrees C lowers the adsorption density of fluoride.

  17. 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

  18. 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

  19. 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.

  20. Kinetics of the degradation of SKF-12 rubber and analysis of the volatile products by the mass-spectrometric method

    SciTech Connect

    Khakimova, R.; Usmanov, K.U.; Eshbaev, F.

    1983-03-01

    Among synthetic polymers, the fluorine-containing rubbers SKF-32 and SKF-26 (copolymers of vinylidene fluoride with chlorotrifluoroethylene and hexafluoropropylene) occupy a special place. Their valuable properties (high thermal resistance, chemical resistance, and resistance to the action of aggressive media) have brought about the wide use of articles based on them in various branches of industry and the national economy. A study of the kinetics of the thermodynamic and thermo-oxidative degradation of the investigated specimens was carried out by the thermogravimetry method on the McBain balance over the range 603-623/sup 0/K. Mass-spectral analysis was applied to the volatile products. On the basis of the results obtained, we may conclude that a deep and detailed study of the kinetics of degradation and analysis of the volatile products by contempory methods affords the possibility of solving questions pertaining to the structural changes which take place in polymers during the process of various types of aging. Results of these studies can be used in further work on the application of the class of compounds based on benzofuran derivatives as thermo-stabilizers for other fluorine-containing polymers.

  1. Conditioning matrices from high level waste resulting from pyrochemical processing in fluorine salt

    SciTech Connect

    Grandjean, Agnes; Advocat, Thierry; Bousquet, Nicolas; Jegou, Christophe

    2007-07-01

    Separating the actinides from the fission products through reductive extraction by aluminium in a LiF/AlF{sub 3} medium is a process investigated for pyrometallurgical reprocessing of spent fuel. The process involves separation by reductive salt-metal extraction. After dissolving the fuel or the transmutation target in a salt bath, the noble metal fission products are first extracted by contacting them with a slightly reducing metal. After extracting the metal fission products, then the actinides are selectively separated from the remaining fission products. In this hypothesis, all the unrecoverable fission products would be conditioned as fluorides. Therefore, this process will generate first a metallic waste containing the 'reducible' fission products (Pd, Mo, Ru, Rh, Tc, etc.) and a fluorine waste containing alkali-metal, alkaline-earth and rare earth fission products. Immobilization of these wastes in classical borosilicate glasses is not feasible due to the very low solubility of noble metals, and of fluoride in these hosts. Alternative candidates have therefore been developed including silicate glass/ceramic system for fluoride fission products and metallic ones for noble metal fission products. These waste-forms were evaluated for their confinement properties like homogeneity, waste loading, volatility during the elaboration process, chemical durability, etc. using appropriate techniques. (authors)

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Industrial wastewaters often consist of a complex chemical cocktail with treatment of target contaminants complicated by adverse chemical reactions. The impact of metal ions (Cd2 +, Ba2 + and Mn2 +) on the kinetics of fluoride removal from solution by natural zeolite was investigated. In order to better understand the kinetics, the pseudo-second order (PSO), Hill (Hill 4 and Hill 5) and intra-particle diffusion (IPD) models were applied. Model fitting was compared using the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). The Hill models (Hill 4 and Hill 5) were found to be superior in describing the fluoride removal processes due to the sigmoidal nature of the kinetics. Results indicate that the presence of Mn (100 mg L- 1) and Cd (100 mg L- 1) respectively increases the rate of fluoride sorption by a factor of 28.3 and 10.9, the maximum sorption capacity is increased by 2.2 and 1.7. The presence of Ba (100 mg L- 1) initially inhibited fluoride removal and very poor fits were obtained for all models. Fitting was best described with a biphasic sigmoidal model with the degree of inhibition decreasing with increasing temperature suggesting that at least two processes are involved with fluoride sorption onto natural zeolite in the presence of Ba.

  3. Simultaneous removal of arsenic and fluoride from groundwater by coagulation-adsorption with polyaluminum chloride.

    PubMed

    Ingallinella, Ana M; Pacini, Virginia A; Fernández, Rubén G; Vidoni, Romina M; Sanguinetti, Graciela

    2011-01-01

    The ArCIS-UNR® arsenic and fluoride removal system which consists of a coagulation-adsorption process with initial pH adjustment and two filtration stages (up-flow gravel roughing filtration and rapid filtration), has been already described in previous studies. This process has been successfully implemented in full-scale plants in Argentina, with fluoride and total arsenic concentrations in raw water up to 2 mg/L and 200 μg/L, respectively. The aim of the present study is to optimize fluoride removal when it is >2.0 mg/L. The modifications proposed were to decrease the pH level to 6.4-6.6 at the roughing filter inlet and increase the pH level to 7.2-7.6 at the rapid filter inlet to decrease residual aluminum concentration. Laboratory and pilot scale studies were performed using natural water with fluoride concentrations ranging from 2.4 to 3.2 mg/L and arsenic concentrations from 60 to 90 μg/L. An optimal combination of operational parameters and the coagulant dose (polyaluminum chloride, PACl) was found, to achieve final concentrations of fluoride, arsenic and aluminum in treated water lower than those set by the regulations in force. Filtration run time was 10 to 12 hours; research studies are necessary to extend this period.

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

    PubMed

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

    2015-01-01

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

  5. 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)

  6. Effect of Fluoride Concentration on Reduction of Enamel Demineralization According to the Cariogenic Challenge.

    PubMed

    Noronha, Mayara Dos Santos; Romão, Dayse Andrade; Cury, Jaime Aparecido; Tabchoury, Cínthia Pereira Machado

    2016-01-01

    Fluoride present in toothpaste at 1,100 µg/g is considered effective on caries control. However, under high cariogenic challenge due to increasing sugar exposure, higher fluoride concentration (5,000 µg/g) could be necessary to compensate the unbalance on caries process. This was tested in a pH-cycling regimen, which evaluated the effect of fluoride concentration relative to toothpaste on reduction of enamel demineralization under conditions of two levels of cariogenic challenge. Enamel slabs (n=20) were subjected to two pH-cycling regimens, simulating 8x and 16x/day sugar exposure and were treated with solutions containing: 0 (no fluoride), 275 or 1,250 µg F/mL, resulting in 6 treatment groups: 4-h/0-F; 8-h/0-F; 4-h/275-F; 8-h/275-F; 4-h/1,250-F and 8-h/1,250-F. The 275 and 1,250 µg F/mL concentrations simulate mouth salivary dilution when 1,100 and 5,000 µg/g toothpastes are used. Enamel demineralization was assessed by surface (%SHL) and cross-sectional hardness. Fluoride taken up by enamel was also evaluated. Data were analyzed by ANOVA one-way and Tukey's test. The treatment with 1,250 µg F/mL significantly reduced %SHL compared with 275 µg F/mL (p<0.05), irrespective the level of cariogenic challenge (4-h/1,250-F vs. 4-h/275-F and 8-h/1,250-F vs 8-h/275-F comparisons, respectively). These data were supported by fluoride concentration found in enamel. These findings suggest that higher fluoride concentrations could partly compensate the greater caries risk under higher cariogenic challenge due to increasing sugar exposure.

  7. 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.

  8. Losses of components of fluoride-phosphate glasses in the course of synthesis

    SciTech Connect

    Galant, V.E.; Urusovskaya, L.N.

    1988-04-20

    The purpose of this work was to study component losses during synthesis of fluoride-phosphate glasses in the system Al(PO/sub 3/)/sub 3/-BaF/sub 2/-AlF/sub 3/-MeF/sub x/ in relation to the nature and concentration of the added fluoride. The composition of the original glass (mole %) was: Al(PO/sub 3/)/sub 3/ 22.80, BaF/sub 2/ 66.66, AlF/sub 3/ 10.54. From 1 to 35% of MeF (Me = Li, Na, K, Rb, Cs, Tl), and from 5 to 30 mole % of MeF/sub 2/ (Me = Mg, Ca, Sr, Zn, Cd, Ba), and from 5 to 35 mole % of MeF/sub 3/ (Me = Al, Ga, In, Sc, Y, La) was added to the original glass. A calculation method based on comparison of the glass compositions by synthesis and analysis was used for determination of component losses by volatilization during the melting. The authors dual investigation of the composition of the products of volatilization of the glass-forming system Al(PO/sub 3/)/sub 3/-BaF/sub 2/-AlF/sub 3/-MeF/sub x/ demonstrates that the principal volatilization products are the compounds POF/sub 3/, PF/sub 3/, and MeF/sub x/. Moreover, the volatile phase may contain PF/sub 3/, AlF/sub 3/, BaF/sub 2/, P/sub 2/O/sub 5/, and in the case of the system with TlF the complex compound TlSlF/sub 4/ may be formed.

  9. Volatile components and continental material of planets

    NASA Technical Reports Server (NTRS)

    Florenskiy, K. P.; Nikolayeva, O. V.

    1986-01-01

    It is shown that the continental material of the terrestrial planets varies in composition from planet to planet according to the abundances and composition of true volatiles (H20, CO2, etc.) in the outer shells of the planets. The formation of these shells occurs very early in a planet's evolution when the role of endogenous processes is indistinct and continental materials are subject to melting and vaporizing in the absence of an atmosphere. As a result, the chemical properties of continental materials are related not only to fractionation processes but also to meltability and volatility. For planets retaining a certain quantity of true volatile components, the chemical transformation of continental material is characterized by a close interaction between impact melting vaporization and endogeneous geological processes.

  10. Dynamic headspace analyses of residual volatiles in pharmaceuticals.

    PubMed

    Wampler, T P; Bowe, W A; Levy, E J

    1985-02-01

    Pharmaceutical preparations may be assayed for volatile organic compounds by purging them with a stream of inert carrier gas and collecting the organics onto a suitable sorbent material, from which they may be backflushed to a gas chromatograph. Compared to solvent extraction, the process offers advantages of increased sensitivity, ease of automation, and elimination of the solvent peak. Examples are given of three major sources of volatiles in pharmaceuticals, with the development of a method for quantitating the volatiles using an internal standard.

  11. Fractionation of moderately volatile elements in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Wasson, J. T.; Chou, C.-L.

    1974-01-01

    The CI chondrites are the most volatile-rich meteorites. Relative to the CI chondrites, the ordinary chondrites have lower abundances of refractory and volatile elements. Four types of fractionations are summarized in a table. Ordinary-chondrite/CI abundance ratios for moderately volatile elements in H- and L-group chondrites are presented in a graph. Possible explanations for the observed relations are considered, giving attention to several processes which could result in the separation of nebular solids and gases.

  12. Changes in physicochemical and biological properties of porcine bone derived hydroxyapatite induced by the incorporation of fluoride

    PubMed Central

    Qiao, Wei; Liu, Quan; Li, Zhipeng; Zhang, Hanqing; Chen, Zhuofan

    2017-01-01

    Abstract As the main inorganic component of xenogenic bone graft material, bone-derived biological apatite (BAp) has been widely used in implant dentistry, oral and maxillofacial surgery and orthopedics. However, BAp produced via calcination of animal bones still suffers from some drawbacks, such as insufficient mechanical strength and inadequate degradation rate, which impede its application. Fluoride is known to play important roles in both physiological and pathological processes of human hard tissues for its double effects on bones and teeth. In order to understand the effects of fluoride on the properties of BAp, as well as the mechanism behind them, porcine bone derived hydroxyapatite (PHAp) was prepared via thermal treatment, which was then fluoride incorporated at a series concentrations of sodium fluoride, and noted as 0.25-FPHAp, 0.50-FPHAp, and 0.75-FPHAp respectively. The physicochemical characteristics of the materials, including crystal morphology, crystallinity, functional groups, elemental composition, compressive strength, porosity and solubility, were then determined. The biological properties, such as protein adsorption and cell attachment, were also evaluated. It was found that the spheroid-like crystals of PHAp were changed into rod-like after fluoride substitution, resulting in a fluoride concentration-dependent increase in compressive strength, as well as a decreased porosity and solubility of the apatite. However, even though the addition of fluoride was demonstrated to enhance protein adsorption and cell attachment of the materials, the most favorable results were intriguingly achieved in FPHAp with the least fluoride content. Collectively, low level of fluoride incorporation is proposed promising for the modification of clinically used BAp based bone substitute materials, because of its being able to maintain a good balance between physicochemical and biological properties of the apatite. PMID:28243337

  13. Volatile and trace element composition of melt inclusions from the Lower Bandelier Tuff - implications for magma chamber processes and eruptive style

    SciTech Connect

    Dunbar, N.W.; Hervig, R.L. |

    1992-10-01

    The preeruptive volatile gradient that was present in the magma which produced the Lower Bandelier Tuff (LBT) is determined on the basis of an analysis of the H{sub 2}O, Cl, and F contents of melt inclusions (MIs) in LBT phenocrysts. The trace element contents of bulk pumice and MIs are measured in order to facilitate interpretation of the pristine nature of the MIs. The data show that there was a large gradient in the H2O content (hence density) of the magma between an H2O-saturated cap and the body of the chamber. The trace element analysis of the MIs and bulk rocks show that after the water gradient evolved, the chamber underwent about 40 percent eutectic fractional crystallization and was then intruded by a second rhyolitic magma at some time prior to eruption. 75 refs.

  14. Tetracycline removal and effect on the formation and degradation of extracellular polymeric substances and volatile fatty acids in the process of hydrogen fermentation.

    PubMed

    Hou, Guangying; Hao, Xiaoyan; Zhang, Rui; Wang, Jing; Liu, Rutao; Liu, Chunguang

    2016-07-01

    Many research indicate antibiotics show adverse effect on methane fermentation, while few research focus on their effect on hydrogen fermentation. The present study aimed to gain insight of the effect of antibiotics on hydrogen fermentation with waste sludge and corn straw as substrate. For this purpose, tetracycline, as a model, was investigated with regard to tetracycline removal, hydrogen production, interaction with extracellular polymeric substances (EPSs) of substrate and volatile fatty acids (VFAs) on concentration and composition. Results show that tetracycline could be removed efficiently by hydrogen fermentation, and relative low-dose tetracycline (200mg/l) exposure affects little on hydrogen production. While tetracycline exposure could change hydrogen fermentation from butyric acid-type to propionic acid-type depending on tetracycline level. Based upon three-dimensional excitation-emission matrix fluorescence spectroscopy and UV-vis tetracycline changed the component and content of EPSs, and static quenching was the main mechanism between EPSs with tetracycline.

  15. 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.

  16. 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)

  17. 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.

  18. 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.

  19. Microwave Extraction of Volatiles for Mars Science and ISRU

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaulker, William F.

    2012-01-01

    The greatest advantage of microwave heating for volatiles extraction is that excavation can be greatly reduced. Surface support operations would be simple consisting of rovers with drilling capability for insertion of microwaves down bore holes to heat at desired depths. The rovers would also provide support to scientific instruments for volatiles analysis and for volatiles collection and storage. The process has the potential for a much lower mass and a less complex system than other in-situ processes. Microwave energy penetrates the surface heating within with subsequent sublimation of water or decomposition of volatile containing minerals. On Mars the volatiles should migrate to the surface to be captured with a cold trap. The water extraction and transport process coupled with atmospheric CO2 collection could readily lead to a propellant production process, H2O + CO2 yields CH4 + O2.

  20. Volatile organic compound sensor system

    DOEpatents

    Schabron, John F.; Rovani, Jr., Joseph F.; Bomstad, Theresa M.; Sorini-Wong, Susan S.; Wong, Gregory K.

    2011-03-01

    Generally, this invention relates to the development of field monitoring methodology for new substances and sensing chemical warfare agents (CWAs) and terrorist substances. It also relates to a portable test kit which may be utilized to measure concentrations of halogenated volatile organic compounds (VOCs) in the field. Specifically it relates to systems for reliably field sensing the potential presence of such items while also distinguishing them from other elements potentially present. It also relates to overall systems and processes for sensing, reacting, and responding to an indicated presence of such substance, including modifications of existing halogenated sensors and arrayed sensing systems and methods.

  1. Volatile organic compound sensor system

    DOEpatents

    Schabron, John F.; Rovani, Jr., Joseph F.; Bomstad, Theresa M.; Sorini-Wong, Susan S.

    2009-02-10

    Generally, this invention relates to the development of field monitoring methodology for new substances and sensing chemical warfare agents (CWAs) and terrorist substances. It also relates to a portable test kit which may be utilized to measure concentrations of halogenated volatile organic compounds (VOCs) in the field. Specifically it relates to systems for reliably field sensing the potential presence of such items while also distinguishing them from other elements potentially present. It also relates to overall systems and processes for sensing, reacting, and responding to an indicated presence of such substance, including modifications of existing halogenated sensors and arrayed sensing systems and methods.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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)

  9. Efficient removal of fluoride by hierarchical MgO microspheres: Performance and mechanism study

    NASA Astrophysics Data System (ADS)

    Jin, Zhen; Jia, Yong; Luo, Tao; Kong, Ling-Tao; Sun, Bai; Shen, Wei; Meng, Fan-Li; Liu, Jin-Huai

    2015-12-01

    Hierarchical MgO microspheres assembled by numerous porous nanoplates were successfully obtained by annealing the precursors of magnesium carbonate hydroxide hydrate synthesized through a facile and cost-effective hydrothermal process at low temperature. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller measurements. The fluoride removal performance of the hierarchical MgO microspheres was investigated. The adsorption isotherm could be well fitted in Freundlich model, and the adsorption capacity was over 115.5 mg/g at pH 7. The absorbent also showed high fluoride removal ability in a wide pH range of 2-10, which is favorable for practical application. The effect of co-existing anions on fluoride removal was also investigated. The result indicated that the fluoride adsorption capacity was influenced when carbonate, bicarbonate and phosphate existed above the concentration of 50 mg/g. In addition, the adsorption mechanism was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A novel hydroxyl and carbonate co-exchange mechanism has been proposed for the first time. It can be found that fluoride ions could replace the surface carbonates which formed by the reaction of MgO and the adsorbed CO2 molecules, and then anchored on the MgO surface.

  10. Theoretical and NMR experimental insights on urea, thiourea and diindolyurea as fluoride carriers

    NASA Astrophysics Data System (ADS)

    Mendonça, João Guilherme P.; Silla, Josué M.; Andrade, Laize A. F.; Fernandes, Sergio A.; Cormanich, Rodrigo A.; Freitas, Matheus P.

    2016-06-01

    Urea and thiourea derivatives are widely known as anion transporters. The pristine urea and thiourea compounds were theoretically and spectroscopically evaluated as fluoride ligands, since transportation of F- is involved in many biochemical processes and this anion is suitable to be analyzed through NMR. Conformational changes induced by anions can be useful to probe ligand-anion complexation, but urea and thiourea do not undergo conformational isomerization. Thus, diindolylurea (DIU) was computationally investigated to search for its conformational preferences upon complexation with fluoride. Overall, the NMR proton signal for urea and thiourea moved downfield and broadened upon addition of one equivalent of fluoride anion in DMSO solution, indicating complexation. The 19F signal for the thiourea-F- mixture also shifted relative to the anion source. However, a J(N)H,F coupling constant was not observed, probably because of entropy and bulk solvation effects. In addition, the conformational preference of DIU changed drastically after simulated complexation with fluoride, in agreement with previous studies with other anions. This confirms the potential of urea derivatives as fluoride carriers.

  11. Hydrothermal synthesis and formation mechanism of hexagonal yttrium hydroxide fluoride nanobundles

    SciTech Connect

    Tian, Li; Sun, QiLiang; Zhao, RuiNi; He, HuiLin; Xue, JianRong; Lin, Jun

    2013-11-15

    Graphical abstract: The formation of yttrium hydroxide fluorides nanobundles can be expressed as a precipitation transformation from cubic NaYF{sub 4} to hexagonal NaYF{sub 4} and to hexagonal Y(OH){sub 2.02}F{sub 0.98} owing to ion exchange. - Highlights: • Novel Y(OH){sub 2.02}F{sub 0.98} nanobundles have been successfully prepared by hydrothermal method. • The branched nanobundles composed of numerous oriented-attached nanoparticles has been studied. • The growth mechanism is proposed to be ion exchange and precipitation transformation. - Abstract: This article presents the fabrication of hexagonal yttrium hydroxide fluoride nanobundles via one-pot hydrothermal process, using yttrium nitrate, sodium hydroxide and ammonia fluoride as raw materials to react in propanetriol solvent. The X-ray diffraction pattern clearly reveals that the grown product is pure yttrium hydroxide fluoride, namely Y(OH){sub 2.02}F{sub 0.98}. The morphology and microstructure of the synthesized product is testified to be nanobundles composed of numerous oriented-attached nanoparticles as observed from the field emission scanning electron microscopy (FESEM). The chemical composition was analyzed by the energy dispersive spectrum (EDS), confirming the phase transformation of the products which was clearly consistent with the result of XRD analysis. It is proposed that the growth of yttrium hydroxide fluoride nanobundles be attributed to ion exchange and precipitation transformation.

  12. 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.

  13. 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.

  14. 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.

  15. VOLATILE POLAR METABOLITES IN EXHALED BREATH CONDENSATE (EBC): COLLECTION AND ANALYSIS

    EPA Science Inventory

    Environmental exposures, individual activities, and disease states can perturb normal metabolic processes and be expressed as a change in the patterns of polar volatile organic compounds (PVOCs) present in biological fluids. We explore the measurement of volatile endogenous bioma...

  16. 75 FR 72963 - Approval and Promulgation of Air Quality Implementation Plans; Maryland; Control of Volatile...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-29

    ... Volatile Organic Compound Emissions From Industrial Solvent Cleaning Operations; Withdrawal of Direct Final... Organic Compounds from Specific Processes Regulation. Maryland Department of the Environment (MDE) adopted... technology (RACT) requirements for sources of volatile organic compounds (VOCs) covered by control...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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.

  4. 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...

  5. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 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...

  6. 40 CFR 60.212 - 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. 60.212 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...

  7. Health effects of fluoride pollution caused by coal burning.

    PubMed

    Ando, M; Tadano, M; Yamamoto, S; Tamura, K; Asanuma, S; Watanabe, T; Kondo, T; Sakurai, S; Ji, R; Liang, C; Chen, X; Hong, Z; Cao, S

    2001-04-23

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

  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. Resin-modified glass ionomer cements: fluoride release and uptake.

    PubMed

    Forsten, L

    1995-08-01

    The aim was to study the short- and long-term fluoride release from resin-modified glass ionomer cements (GIC). The aim was also to determine the effect of fluoride treatment of 9-month-old specimens, consistency of the mix, and pH of the environment on the fluoride release. GIC test specimens were continually exposed to running water, and the fluoride release was measured periodically by storing the specimens in 5 ml deionized water for 1 week and measuring the fluoride content of the solution. After 24 h, 1 month, 9 months, and 11 months in running water four of the six resin-modified GICs released as much as or more fluoride than the auto-curing GIC tested for comparison. Fluoride treatment after 9 months also increased the fluoride release of these four brands, as was the case with the conventional GIC. At 24 h and 1 month two of the resin-modified GICs released smaller amounts of fluoride than the other materials, and the fluoride treatment used on those had no or only a minimal effect. Thin consistency of a mix resulted in higher fluoride release for one resin-modified material than a thick mix. Low pH increased the fluoride release for all materials.

  10. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    SciTech Connect

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  11. 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

    process of percolation with fluoride-bearing country rocks under arid, low precipitation, and high evapotranspiration conditions.

  12. Fluoride-Induced Oxidative and Inflammatory Stress in Osteosarcoma Cells: Does It Affect Bone Development Pathway?

    PubMed

    Gandhi, Deepa; Naoghare, Pravin K; Bafana, Amit; Kannan, Krishnamurthi; Sivanesan, Saravanadevi

    2017-01-01

    Oxidative stress is reported to negatively affect osteoblast cells. Present study reports oxidative and inflammatory signatures in fluoride-exposed human osteosarcoma (HOS) cells, and their possible association with the genes involved in osteoblastic differentiation and bone development pathways. HOS cells were challenged with sublethal concentration (8 mg/L) of sodium fluoride for 30 days and analyzed for transcriptomic expression. In total, 2632 transcripts associated with several biological processes were found to be differentially expressed. Specifically, genes involved in oxidative stress, inflammation, osteoblastic differentiation, and bone development pathways were found to be significantly altered. Variation in expression of key genes involved in the abovementioned pathways was validated through qPCR. Expression of serum amyloid A1 protein, a key regulator of stress and inflammatory pathways, was validated through western blot analysis. This study provides evidence that chronic oxidative and inflammatory stress may be associated with the fluoride-induced impediment in osteoblast differentiation and bone development.

  13. TESTING OF 304L STAINLESS STEEL IN NITRIC ACID ENVIRONMENTS WITH FLUORIDES AND CHLORIDES

    SciTech Connect

    Mickalonis, J.

    2010-10-04

    Impure radioactive material processed in nitric acid solutions resulted in the presence of chlorides in a dissolver fabricated from 304L stainless steel. An experimental program was conducted to study the effects of chloride in nitric acid/fluoride solutions on the corrosion of 304L stainless steel. The test variables included temperature (80, 95, and 110 C) and the concentrations of nitric acid (6, 12, and 14 M), fluoride (0.01, 0.1, and 0.2 M) and chloride (100, 350, 1000, and 2000 ppm). The impact of welding was also investigated. Results showed that the chloride concentration alone was not a dominant variable affecting the corrosion, but rather the interaction of chloride with fluoride significantly affected corrosion.

  14. CURRENT STATUS OF INSTRUMENTATION FOR A FLUORIDE SALT HEAT TRANSPORT DEMONSTRATION LOOP

    SciTech Connect

    Kisner, Roger A; Holcomb, David Eugene

    2010-01-01

    A small forced convection liquid fluoride salt loop is under construction at Oak Ridge National Laboratory (ORNL) to examine the heat transfer behavior of FLiNaK in a heated pebble bed. Loop operation serves several purposes: (1) reestablishing the infrastructure necessary for fluoride salt loop testing, (2) demonstrating a wireless heating technique for simulating pebble type fuel, (3) demonstration of the integration of silicon carbide (SiC) and metallic components into a liquid salt loop, and (4) demonstration of the functionality of distinctive instrumentation required for liquid fluoride salts. Loop operation requires measurement of a broad set of process variables including temperature, flow, pressure, and level. Coolant chemistry measurements (as a corrosion indicator) and component health monitoring are also important for longer-term operation. Two dominating factors in sensor and instrument selection are the high operating temperature of the salt and its chemical environment.

  15. Fluoride and mineral redeposition in outermost layers of bovine enamel during surface softening.

    PubMed

    Rentsch, H; Merte, K; Zschau, H E; Plier, F; Otto, G; Vogt, J

    1990-01-01

    Mineral and fluoride concentration changes in the outermost layers of bovine enamel (depth less than 1 micron) were measured after demineralization in unbuffered hydroxyethylcellulose gels of pH = 5.4 with an intrinsic fluoride concentration of about 0.02 ppm. A combination of two nuclear analytical techniques, Rutherford backscattering spectrometry (RBS) and proton-induced gamma ray emission spectrometry (PIGE) was applied to determine the Ca/P molar ratios and F depth profiles, respectively. When compared to deeper layers, a reduced loss of mineral content is observed for the depth range of about 0-0.1 micron corresponding well with a F concentration increase from about 500 to about 5,000 ppm in the same range. These findings are interpreted as a fluoride-induced partial remineralization of the superficial surface layer during an overall demineralization process.

  16. Investigation on fixed bed column performance of fluoride adsorption by sugarcane charcoal.

    PubMed

    Mondal, N K; Bhaumik, R; Roy, P; Das, B; Datta, J K

    2013-11-01

    The present study explores the potentiality of sugarcane charcoal for fluoride removal from synthetic fluoride solution. Column adsorption experiments with respect to variation of flow rate, pH, initial concentration, and column depths were carried out. Sugarcane charcoal exhibited almost consistent scavenging capacity at various bed depths with a flow rate 4.34 ml min(-1). Maximum adsorption capacity of sugarcane charcoal was recorded 7.33 mg g(-1). The adsorption studies were simulated using Thomas and Bed depth service time model. Both the models consistently predict its characteristic parameters and describe the breakthrough profiles in the whole range of sorption process.

  17. Graphite Fluoride Fiber Composites For Heat Sinking

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

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

    PubMed

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

    2016-04-01

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

  19. [Chemical form changes of exogenous water solution fluoride and bioavailability in tea garden soil].

    PubMed

    Cai, Hui-Mei; Peng, Chuan-Yi; Chen, Jing; Hou, Ru-Yan; Wan, Xiao-Chun

    2013-11-01

    Pot experiments and the sequential extraction method were conducted to study the chemical form changes of exogenous water solution fluoride in tea garden soil and their contribution to fluoride accumulation of tea plant. The results showed that the background concentration of all chemical forms of fluoride had little changes with time treatment, which was in a relatively stable state. The exogenous water solution fluoride adding to the soils was rapidly transformed to other fractions. Under the 10 mg x kg(-1) fluoride treatment, the concentration of water solution fluoride increased firstly and then decreased with time treatment, the concentration of organic matter fluoride and Fe/Mn oxides fluoride decreased, the concentration of exchangeable fluoride was not different before and after the treatment (P > 0.05), and the concentration of residual fluoride was in a relatively stable state; under the 200 mg x kg(-1) fluoride treatment, the concentration of water solution fluoride, Fe/Mn oxides fluoride and organic matter fluoride decreased with time treatment, the concentration of exchangeable fluoride increased firstly and then decreased, showed no difference before and after the treatment (P > 0.05), and the concentration of residual fluoride increased, with some differences compared with 10 mg x kg(-1) fluoride treatment. The concentration of total fluoride in root, stem and leaf had significant differences under 0-10 mg x kg(-1) fluoride treatment (P < 0.05), while showed no difference from 10 to 100 mg x kg(-1) fluoride treatment (P > 0.05). Step regression analysis suggested the contribution of all chemical forms of fluoride to the concentration of water solution fluoride and total fluoride of root, stem and leaf had some differences, there was a remarkable regression relationship among the content of total fluoride in leaf and water solution fluoride, organic matter fluoride, Fe/Mn oxides fluoride and residual fluoride in soil, however, no significant

  20. Lunar volatiles: balancing science and resource development

    NASA Astrophysics Data System (ADS)

    Crider, Dana

    In the context of human exploration of the moon, the volatiles postulated to exist at the lunar poles have value as resources as well as scientific significance. Once sustained human operations commence on the moon, society will move from a paradigm in which examination of planetary materials has been unconstrained to one where use of those materials will support habitability and further exploration. A framework for the scientific investigation of lunar volatiles that allows for eventual economic exploitation can guide both activities and resolve the conflicts that will inevitably develop if the postulated lunar volatiles prove to be both extant and accessible. Scientific constraints on the framework include characterization at both poles of the isotopes, elements, and molecules in the volatiles, their relative and absolute abundances, and their horizontal and vertical distribution. A subset of this data is necessary in order to assess, develop, and initiate resource exploitation. In addition, the scientific record of volatiles in the cold traps can be contaminated by the cold-trapping of migrating volatiles released from operations elsewhere on the moon even if the indigenous, cold-trapped volatiles are not utilized. Possible decision points defining the transition from science-dominated to exploitation-dominated use include technology limits in the 70K environment, evolving science priorities (funding), and the resolution of major science issues. Inputs to policy development include any North vs. South Pole differences in volatile characteristics and the suitability of the volatiles to enable further scientific exploration of the moon. In the absence of national sovereignty on the moon, enforcement of any framework is an open question, particularly if science and commercial interests are in competition. The framework, processes, and precedent set by how we as a society choose to handle the scientific bounty and resource promise of lunar volatiles may eventually

  1. Accumulation of semi-volatile organic compounds in moss (Sphagnum Species) and spruce needles (Picea Mariana): Whole-leaf absorption vs. surface adsorption processes

    SciTech Connect

    Hornbuckle, K.C.; Eisenreich, S.J.

    1996-12-31

    Vapor exchange of semi-volatile organic compounds (SOCs) with plant surfaces may control the fate of SOCS far from their original sources. For example, plants may act as sinks for released SOCs by adsorbing the compounds and burying them upon the plant`s death. Evidence for this hypothesis lies in the accumulation of SOCs in peat moss. Alternatively, plants may act as temporary {open_quote}resting points{close_quote} for long-range transport of the compounds from warmer regions to cooler regions. Studies that show higher SOC concentrations in plants collected from cooler parts of the globe are evidence for this hypothesis. Whether vapor-phase SOCs are taken up or released by plants is expected to depend on characteristics of the compound, the plant, and the local climate. Theoretically, it has been predicted that temperature and SOC hydrophobicity should dominate vapor exchange. The effect of these two factors on vapor-plant exchange has been examined through two concurrent and related studies. The first study concerns the vapor SOC dynamics in a semi-remote forested bog in northern Minnesota. The second study concerns the measured distribution between vapor and plant-associated SOCs in the same bog.

  2. Synthesis of complex fluorides for optical applications

    NASA Astrophysics Data System (ADS)

    Stepleton, Seth Eugene

    Large single crystals of alkali metal fluorides are desirable for many reasons. Fluoride laser crystals have a wide transmission range and on account of their low phonon energies, many efficient laser emissions have been obtained from 285 nm to 4.34 microm.1,2 Inorganic fluoride single crystals feature large bandgaps, very wide optical transmittance ranges from vacuum-ultraviolet (VUV) to mid-IR wavelength regions, lower refractive indices than those of oxides, and typically lower phonon energies (which drastically reduce multiphonon relaxation rates of rare earth ions).3 The main goal of this work was to investigate the hydrothermal synthesis of alkali metal fluorides. Melt techniques have been used thoroughly to research a variety of fluoride systems and showed many phases that were inaccessible due to incongruent melting or phase stability. The existence of these phases was shown but never characterized or grown as a crystalline material. Solution growth in supercritical water was an ideal way to attempt the synthesis of novel compounds and phases. New synthetic routes to known phases and compounds also arose as a part of this work. Optically clear colorless crystals of K2BeF4 were synthesized up to 2 mm in size, and showed no phase transitions up to 1029 K, which suggests paraelectricitys at room temperature, contradicting previous reports.4 Attempts to incorporate a rare earth ion into the fluoroberyllate lattice proved unsuccessful however reactions between beryllium fluoride and lanthanide fluorides could be exploited as a synthetic route to single crystal rare earth fluorides. Hydrothermal reactions with KF produced crystals of three different phases: hexagonal KY2F7, trigonal KYF4 and orthorhombic K2YF5. All were optically clear, colorless crystals, with the K2YF5 crystals growing the largest. This compound is beneficial due to its application as a radiation dosimeter and laser host. 5,6 Optical quality colorless crystals of RbY2F7 and CsY2F7 up to 4 mm in

  3. Fluoride release from restorative materials.

    PubMed

    Basso, Gabriela Romanini; Della Bona, Alvaro; Gobbi, Delton Luiz; Cecchetti, Dileta

    2011-01-01

    The aim of this study was to evaluate in vitro fluoride (F) release from 4 restorative materials (3M ESPE): Ketak Molar Easymix [KME - conventional glass ionomer cement (GIC)]; Rely-X luting 2 [RL2 - resin-modified GIC (RMGIC)]; Vitremer (VIT- RMGIC); and Filtek Z250 [Z250 - negative control]. Disc-shaped specimens were fabricated according to the manufacturer's instructions and placed into 10 mL of reverse osmosis water at 37°C until the analyses were done using a liquid membrane for selective F ion electrode (Orion 710). F release was evaluated every 6 h in the first day and thereafter daily during 28 days (d). The results were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Mean F release and standard deviation values (in ppm) were: KME: 6 h- 0.34 ± 0.04; 24 h- 1.22 ± 0.30; 7 d- 0.29 ± 0.09; 14 d- 0.20 ± 0.04; 28 d- 0.16 ± 0.01; RL2: 6 h- 2.46 ± 0.48; 24 h-12.33 ± 2.93; 7 d- 1.37 ± 0.38; 14 d- 0.80 ± 0.13; 28 d- 0.80 ± 0.21; VIT: 6 h- 0.98 ± 0.35; 24 h- 4.35 ± 1.22; 7 d- 0.66 ± 0.23; 14 d- 0.40 ± 0.07; 28 d- 0.39 ± 0.08; Z250: 6 h- 0.029 ± 0.001; 24 h- 0.024 ± 0.009; 7 d- 0.023 ± 0.004; 14 d- 0.025 ± 0.001; 28 d- 0.028 ± 0.001. RL2 RMGIC released more F than the other materials in all periods. The greatest release of F occurred in the first 24 h.

  4. Configuration of Pluto's Volatile Ices

    NASA Astrophysics Data System (ADS)

    Grundy, William M.; Binzel, R. P.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earle, A. M.; Ennico, K.; Jennings, D. E.; Howett, C. J. A.; Linscott, I. R.; Lunsford, A. W.; Olkin, C. B.; Parker, A. H.; Parker, J. Wm; Protopapa, S.; Reuter, D. C.; Singer, K. N.; Spencer, J. R.; Stern, S. A.; Tsang, C. C. C.; Verbiscer, A. J.; Weaver, H. A.; Young, L. A.; Berry, K.; Buie, M. W.; Stansberry, J. A.

    2015-11-01

    We report on near-infrared remote sensing by New Horizons' Ralph instrument (Reuter et al. 2008, Space Sci. Rev. 140, 129-154) of Pluto's N2, CO, and CH4 ices. These especially volatile ices are mobile even at Pluto's cryogenic surface temperatures. Sunlight reflected from these ices becomes imprinted with their characteristic spectral absorption bands. The detailed appearance of these absorption features depends on many aspects of local composition, thermodynamic state, and texture. Multiple-scattering radiative transfer models are used to retrieve quantitative information about these properties and to map how they vary across Pluto's surface. Using parameter maps derived from New Horizons observations, we investigate the striking regional differences in the abundances and scattering properties of Pluto's volatile ices. Comparing these spatial patterns with the underlying geology provides valuable constraints on processes actively modifying the planet's surface, over a variety of spatial scales ranging from global latitudinal patterns to more regional and local processes within and around the feature informally known as Sputnik Planum. This work was supported by the NASA New Horizons Project.

  5. 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

  6. Some electronic and magnetic properties of Fluoride ion in Fluoride structure nanocrystals

    NASA Astrophysics Data System (ADS)

    Imtani, Ali Nasir

    2012-01-01

    We have investigated the effects of the environment potential around Fluoride ion on some important electronic and magnetic properties such as dipole polarisability, moment of oscillator strengths S(k) and magnetic susceptibility. The theoretical procedure is based on the variational-perturbation theory with two parameter trial functions incorporated in an ionic model. We estimate these properties in four cases for Fluoride ion; free ion, ion under different potentials, ion in the crystals and ion in nanocrystal, CdF2, CaF2, PbF2, SrF2 and BaF2. Our results indicate that these properties vary with ion environments and the free state of Fluoride ion has higher values and there is linearity behaviour of these properties with lattice constant. For Fluoride ion in nanocrystal, we have found that there is an extra parameter that can also affect the dipole polarisability, the number of ions in the structure.

  7. Red blood cell glucose metabolism in human chronic fluoride toxicity

    SciTech Connect

    Saralakumari, D.; Rao, P.R. )

    1991-12-01

    Fluoride is a well known inhibitor of many enzyme systems in vitro. The most widely studied classic example of fluoride inhibition is its potent inhibition of glycolysis, specifically its action on the enzyme enolase. Despite the plethora of in vitro studies on the effects of fluoride on the enzyme activity, there is a paucity of information concerning the in vivo metabolic lesions caused by the chronic toxic doses of fluoride in humans. The present study has been undertaken with a view to assess the changes in glucose metabolism and related enzymes in erythrocytes of humans consuming toxic doses of fluoride for prolonged periods.

  8. Fluorides - mode of action and recommendations for use.

    PubMed

    Lussi, Adrian; Hellwig, Elmar; Klimek, Joachim

    2012-01-01

    Various authors have shown that the caries decline in the industrialized countries during recent decades is based on the use of fluorides, of which local fluoride application in the form of fluoridated toothpastes is of primary importance. The caries-protective potential of fluorapatite is quite low; in contrast, dissolved fluorides in the vicinity of enamel are effective both in promoting remineralization and inhibiting demineralization. Considering the fact that the caries decline occurred at the same time that local fluoridation measures became widely used, the conclusion seems justified that regular application of F⁻ can inhibit caries.

  9. 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.

  10. Appropriate uses of fluorides for children: guidelines from the Canadian Workshop on the Evaluation of Current Recommendations Concerning Fluorides.

    PubMed Central

    Clark, D C

    1993-01-01

    OBJECTIVE: To prevent fluorosis caused by excessive fluoride ingestion by revising recommendations for fluoride intake by children. OPTIONS: Limiting fluoride ingestion from fluoridated water, fluoride supplements and fluoride dentifrices. OUTCOMES: Reduction in the prevalence of dental fluorosis and continued prevention of dental caries. EVIDENCE: Before the workshop, experts prepared comprehensive literature reviews of fluoride therapies, fluoride ingestion and the prevalence and causes of dental fluorosis. The papers, which were peer-reviewed, revised and circulated to the workshop participants, formed the basis of the workshop discussions. VALUES: Recommendations to limit fluoride intake were vigorously debated before being adopted as the consensus opinion of the workshop group. BENEFITS, HARMS AND COSTS: Decrease in the prevalence of dental fluorosis with continuing preventive effects of fluoride use. The only significant cost would be in preparing new, low-concentration fluoride products for distribution. RECOMMENDATIONS: Fluoride supplementation should be limited to children 3 years of age and older in areas where there is less than 0.3 ppm of fluoride in the water supply. Children in all areas should use only a "pea-sized" amount of fluoride dentifrice no more than twice daily under the supervision of an adult. VALIDATION: These recommendations are almost identical to changes to recommendations for the use of fluoride supplements recently proposed by a group of European countries. SPONSORS: The workshop was organized by Dr. D. Christopher Clark, of the University of British Columbia, and Drs. Hardy Limeback and Ralph C. Burgess, of the University of Toronto, and funded by Proctor and Gamble Inc., Toronto, the Medical Research Council of Canada and Health Canada (formerly the Department of National Health and Welfare). The recommendations were formally adopted by the Canadian Dental Association in April 1993. PMID:8261348

  11. Multivariate statistical analysis for fluoride occurrence in groundwater in the Northern region of Ghana.

    PubMed

    Salifu, A; Petrusevski, B; Ghebremichael, K; Buamah, R; Amy, G

    2012-10-01

    The presence of excess fluoride in groundwater in the Northern region of Ghana has resulted in the closure of many boreholes for drinking water supply to avoid the incidence of fluorosis and other related health effects. The fluoride concentration in 357 groundwater samples from the area ranged between 0.0 and 11.6mg/L, with a mean value of 1.13mg/L. Piper graphical classification, correlation coefficients, principal component analysis (PCA) and thermodynamic calculations were used as an approach to gain insight into the groundwater chemical composition and to help understand the dominant mechanisms influencing the occurrence of high fluoride waters. Spatial join procedure was used to examine the relationship between the underlying geology of the study area and fluoride distribution. Six groundwater types were identified for the area: Ca-Mg-HCO(3), Ca-Mg-SO(4), Na-Cl, Na-SO(4), Na-HCO(3) and mixed water type. PCA performed on the groundwater chemical data resulted in 4 principal components (PCs) explaining 72% of the data variance. The PCs represented the predominant processes controlling the groundwater chemistry in the study area which include; mineral dissolution reactions, ion exchange processes and evapotranspiration processes. PHREEQC calculations for saturation indices for the groundwater samples indicated they were largely saturated with respect to calcite and under-saturated with respect to fluorite, suggesting that dissolution of fluorite may be occurring in the areas where it is present. A review of the PCA results and an evaluation of the equilibrium state of the groundwater based on the saturation indices, suggest that some of the processes controlling the overall groundwater chemistry in the study area also influenced the fluoride enrichment. These predominant processes include the dissolution of the mineral fluorite, anion exchange processes (F(-)/OH(-)) involving clay minerals and evapotranspiration processes. Elevated fluoride levels in the study

  12. Multivariate statistical analysis for fluoride occurrence in groundwater in the Northern region of Ghana

    NASA Astrophysics Data System (ADS)

    Salifu, A.; Petrusevski, B.; Ghebremichael, K.; Buamah, R.; Amy, G.

    2012-10-01

    The presence of excess fluoride in groundwater in the Northern region of Ghana has resulted in the closure of many boreholes for drinking water supply to avoid the incidence of fluorosis and other related health effects. The fluoride concentration in 357 groundwater samples from the area ranged between 0.0 and 11.6 mg/L, with a mean value of 1.13 mg/L. Piper graphical classification, correlation coefficients, principal component analysis (PCA) and thermodynamic calculations were used as an approach to gain insight into the groundwater chemical composition and to help understand the dominant mechanisms influencing the occurrence of high fluoride waters. Spatial join procedure was used to examine the relationship between the underlying geology of the study area and fluoride distribution. Six groundwater types were identified for the area: Ca-Mg-HCO3, Ca-Mg-SO4, Na-Cl, Na-SO4, Na-HCO3 and mixed water type. PCA performed on the groundwater chemical data resulted in 4 principal components (PCs) explaining 72% of the data variance. The PCs represented the predominant processes controlling the groundwater chemistry in the study area which include; mineral dissolution reactions, ion exchange processes and evapotranspiration processes. PHREEQC calculations for saturation indices for the groundwater samples indicated they were largely saturated with respect to calcite and under-saturated with respect to fluorite, suggesting that dissolution of fluorite may be occurring in the areas where it is present. A review of the PCA results and an evaluation of the equilibrium state of the groundwater based on the saturation indices, suggest that some of the processes controlling the overall groundwater chemistry in the study area also influenced the fluoride enrichment. These predominant processes include the dissolution of the mineral fluorite, anion exchange processes (F-/OH-) involving clay minerals and evapotranspiration processes. Elevated fluoride levels in the study area were

  13. 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

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

    PubMed Central

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

    2013-01-01

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

  15. [Fluoride emission from different soil minerals at high temperatures].

    PubMed

    Wu, W; Xie, Z; Xu, J; Liu, C

    2001-03-01

    The emission characteristics of fluoride pollutants from montmorillonite, kaolinite, vermiculite, geothite and allophane were studied to elucidate the mechanism of fluoride-releasing from soils during brick and tile making at high temperatures from 300 degrees C to 1000 degrees C. The rate of fluoride emission varied with temperature, mineral type, heating time, specific surface area and cations added to minerals. The escape of crystalline water resulting from crystal lattice collapse at a certain high temperature was found to affect the rate of fluoride emission. Calcium compounds could decrease fluoride emission rate from montmorillonite. At 800 degrees C, the rate of fluoride emission from Ca-treated montmorillonite decreased by 59.6% compared to untreated montmorillonite. The order for fluoride-fixing capacity of the 5 calcium compounds at 800 degrees C was as follows: CaCO3 > CaO > Ca3(PO4)2 > Ca(OH)2 > CaSO4.

  16. Palladium-catalyzed substitution of allylic fluorides.

    PubMed

    Hazari, Amaruka; Gouverneur, Véronique; Brown, John M

    2009-01-01

    As unusual substrates for the Tsuji-Trost allylation reaction, allylic fluorides are responsive to palladium-catalyzed substitution. Their activity towards this reaction fits in the series OCO(2)Me>OBz>F>OAc. The classic stereoretention mechanism that involves sequential inversions does not operate in this case. Several distinct cases are considered.

  17. Surface crystallization of a fluoride glass

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Doremus, Robert H.

    1983-01-01

    Growth of crystals on the surface of a Zr-Ba-La fluoride glass was observed by optical and scanning electron microscopy. Small, dark crystal nucleated rapidly and grew to a size of about 10 microns; then they stopped growing, and wrinkled regions emerged, covering the entire crystal surface.

  18. Aqueous vinylidene fluoride polymer coating composition

    NASA Technical Reports Server (NTRS)

    Bartoszek, Edward J. (Inventor); Christofas, Alkis (Inventor)

    1978-01-01

    A water-based coating composition which may be air dried to form durable, fire resistant coatings includes dispersed vinylidene fluoride polymer particles, emulsified liquid epoxy resin and a dissolved emulsifying agent for said epoxy resin which agent is also capable of rapidly curing the epoxy resin upon removal of the water from the composition.

  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. 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