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Sample records for fluoride salts flinak

  1. Effect of moisture on corrosion of Ni-based alloys in molten alkali fluoride FLiNaK salt environments

    NASA Astrophysics Data System (ADS)

    Ouyang, Fan-Yi; Chang, Chi-Hung; You, Bo-Chien; Yeh, Tsung-Kuang; Kai, Ji-Jung

    2013-06-01

    We investigated the corrosion characteristics on several selected alloys at 600 and 700 °C in FLiNaK molten salts with different moisture contents. Hastelloys-N and Hastelloys-B3 exhibited better corrosion resistances, while Haynes 263 showed the poorest corrosion resistance. The mass loss of the tested alloys is primarily determined by the purity of FLiNaK salts; however, the effect of temperature becomes more important on the mass loss of the tested alloys in the non-purified FLiNaK salts. When the residual moisture is present in the FLiNaK salts, the mass losses of the tested alloys varied linearly with original Cr content plus one-third of Mo content. The results of structural characterization revealed that the tested alloys in the FLiNaK salts with higher moisture content would aggravate intergranular corrosion and pitting.

  2. Effects of SO42- ions on the corrosion of GH3535 weld joint in FLiNaK molten salt

    NASA Astrophysics Data System (ADS)

    Zhu, Yasheng; Qiu, Jie; Hou, Juan; Liu, Wenguan; Chen, Huaican; Ai, Hua; Yu, Guojun; Wang, Jianqiang; Zhou, Xingtai

    2017-08-01

    The present work studied the impact of SO42- ions on the corrosion behaviors of GH3535 weld joint in FLiNaK molten salt. The concentration of SO42- ions in the FLiNaK molten salt was controlled by adjusting the quantity of Na2SO4 added into the salt. Results indicate that the SO42- ions in the FLiNaK salt speed up the corrosion rate remarkably by promoting the dissolution of Cr from the alloy matrix into the salt. With the concentration of SO42- ions in the FLiNaK salt increases from 100 ppm to 1000 ppm, the weight losses and the Cr depletion layer depths of the corroded specimens increase linearly. Even in the case of the heavy corrosion attack caused by the SO42- ions, the corrosion performance is similar between the base zone and fusion zone in the GH3535 weld joint. It is demonstrated that the structural diversity caused by the welding process has little impact on the corrosion performances of GH3535 alloy in FLiNaK molten salt.

  3. Thermal performance analysis of a thermocline thermal energy storage system with FLiNaK molten salt

    NASA Astrophysics Data System (ADS)

    Liu, C.; Cheng, M. S.; Zhao, B. C.; Dai, Z. M.

    2017-01-01

    A thermocline thermal storage unit with a heat transfer fluid (HTF) of high-temperature molten salt is considered as one of the most promising methods of thermal storage due to its lower cost and smaller size. The main objective of this work is to analyze the transient behavior of the available molten salt FLiNaK used as the HTF in heat transfer and heat storage in a thermocline thermal energy storage (TES) system. Thermal characteristics including temperature profiles influenced by different inlet velocities of HTF and different void fractions of porous heat storage medium are analyzed. The numerical investigation on the heat storage and heat transfer characteristics of FLiINaK has been carried out. A comparison between two different molten salts, FLiNaK and Hitec, has been explored in this paper with regards to their charging and discharging operations. The results indicate the system with FLiNaK has a greater energy storage capability, a shorter charging time and a higher output power. The numerical investigation reveals heat storage and heat transfer characteristics of the thermocline TES system with FLiNaK, and provide important references for molten salt selection of the TES system in the future.

  4. The influence of FLiNaK salt impregnation on the mechanical properties of a 2D woven C/C composite

    NASA Astrophysics Data System (ADS)

    Zhang, Dongsheng; Xia, Huihao; Yang, Xinmei; Feng, Shanglei; Song, Jinliang; Zhou, Xingtai

    2017-03-01

    Impregnating of molten LiF-NaF-KF salt (LiF-NaF-KF: 46.5-11.5-42 mol%, FLiNaK) into a 2D woven C/C composite was performed at 650 °C under different pressure. The weight gain and mechanical properties change of the 2D woven C/C composite after FLiNaK salt impregnation were measured. The FLiNaK salt distribution into the 2D woven C/C composite was observed by X-ray computed tomography (X-ray CT) and scanning electron microscopy. The results showed that the weight gain of the 2D woven C/C composite increased with increasing impregnating pressure. In X-ray CT images, FLiNaK salt was distributed into the open pores and fissures among fiber bundles and neighboring plies. The interlaminar shear strength, compressive strength, and flexural strength of the 2D woven C/C composite increased with the increase of weight gain. The influence of FLiNaK salt impregnation on the mechanical properties was attributed to the coupling effect of re-densification of FLiNaK salt impregnation and residual stress formed in 2D woven C/C composite.

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

    NASA Astrophysics Data System (ADS)

    Olson, Luke Christopher

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

  6. Salt fluoridation: a review.

    PubMed

    Pollick, Howard F

    2013-06-01

    Salt fluoridation is sometimes suggested as a prospect for communities that have a low water fluoride concentration and have no possibility of implementing community water fluoridation. School-based milk fluoridation programs also are practiced in some countries as an alternative. This paper reviews the evidence of effectiveness in dental caries prevention and risks of dental fluorosis in countries where salt or milk fluoridation is practiced.

  7. Long-term corrosion behaviors of Hastelloy-N and Hastelloy-B3 in moisture-containing molten FLiNaK salt environments

    NASA Astrophysics Data System (ADS)

    Ouyang, Fan-Yi; Chang, Chi-Hung; Kai, Ji-Jung

    2014-03-01

    This study investigated long-term corrosion behaviors of Ni-based Hastelloy-N and Hastelloy-B3 under moisture-containing molten alkali fluoride salt (LiF-NaF-KF: 46.5-11.5-42%) environment at an ambient temperature of 700 °C. The Hastelloy-N and Hastelloy-B3 experienced similar weight losses for tested duration of 100-1000 h, which was caused by aggregate dissolution of Cr and Mo into FLiNaK salts. The corrosion rate of both alloys was high initially, but then reduced during the course of the test. The alleviated corrosion rate was due to the depletion of Cr and Mo near surface of the alloys and thus the long-term corrosion rate was controlled by diffusion of Cr and Mo outward to the alloy surface. The results of microstructural characterization revealed that the corrosion pattern for both alloys tended to be intergranular corrosion at early stage of corrosion test, and then transferred to general corrosion for longer immersion hours.

  8. Examination of Liquid Fluoride Salt Heat Transfer

    SciTech Connect

    Yoder Jr, Graydon L

    2014-01-01

    The need for high efficiency power conversion and energy transport systems is increasing as world energy use continues to increase, petroleum supplies decrease, and global warming concerns become more prevalent. There are few heat transport fluids capable of operating above about 600oC that do not require operation at extremely high pressures. Liquid fluoride salts are an exception to that limitation. Fluoride salts have very high boiling points, can operate at high temperatures and low pressures and have very good heat transfer properties. They have been proposed as coolants for next generation fission reactor systems, as coolants for fusion reactor blankets, and as thermal storage media for solar power systems. In each case, these salts are used to either extract or deliver heat through heat exchange equipment, and in order to design this equipment, liquid salt heat transfer must be predicted. This paper discusses the heat transfer characteristics of liquid fluoride salts. Historically, heat transfer in fluoride salts has been assumed to be consistent with that of conventional fluids (air, water, etc.), and correlations used for predicting heat transfer performance of all fluoride salts have been the same or similar to those used for water conventional fluids an, water, etc). A review of existing liquid salt heat transfer data is presented, summarized, and evaluated on a consistent basis. Less than 10 experimental data sets have been found in the literature, with varying degrees of experimental detail and measured parameters provided. The data has been digitized and a limited database has been assembled and compared to existing heat transfer correlations. Results vary as well, with some data sets following traditional correlations; in others the comparisons are less conclusive. This is especially the case for less common salt/materials combinations, and suggests that additional heat transfer data may be needed when using specific salt eutectics in heat transfer

  9. Salt fluoridation and oral health.

    PubMed

    Marthaler, Thomas M

    2013-11-01

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

  10. SiC coating: An alternative for the protection of nuclear graphite from liquid fluoride salt

    NASA Astrophysics Data System (ADS)

    He, Xiujie; Song, Jinliang; Tan, Jie; Zhang, Baoliang; Xia, Huihao; He, Zhoutong; Zhou, Xingtai; Zhao, Mingwen; Liu, Xiangdong; Xu, Li; Bai, Shuo

    2014-05-01

    SiC coating is produced on a nuclear graphite (NG) substrate using chemical vapor deposition at 1150 °C to protect it from molten salt diffusion. Infiltration studies, performed in molten FLiNaK salt under an argon atmosphere at 5 atm, show that uncoated NG exhibits significantly higher weight gain than SiC-coated NG. The continuous and compact SiC coating exhibits excellent infiltration resistance in liquid fluoride salt as confirmed by synchrotron radiation X-ray microbeam fluorescence.

  11. 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.

  12. Development of a Forced-Convection Liquid-Fluoride-Salt Test Loop

    SciTech Connect

    Yoder Jr, Graydon L; Wilson, Dane F; Peretz, Fred J; Wilgen, John B; Romanoski, Glenn R; Kisner, Roger A; Holcomb, David Eugene; Heatherly, Dennis Wayne; Aaron, Adam M

    2010-01-01

    A small forced-convection molten-fluoride-salt loop is being constructed at Oak Ridge National Laboratory to examine the heat transfer behavior of FLiNaK salt in a heated pebble bed. Objectives of the experiment include reestablishing infrastructure needed for fluoride-salt loop testing, developing a unique inductive heating technique for performing heat transfer (or other) experiments, measuring heat transfer characteristics in a liquid-fluoride-salt-cooled pebble bed, and demonstrating the use of silicon carbide (SiC) as a structural component for salt systems. The salt loop will consist of an Inconel 600 piping system, a sump-type pump, a SiC test section, and an air-cooled heat exchanger, as well as auxiliary systems needed to pre-heat the loop, transport salt into and out of the loop, and maintain an inert cover gas over the salt. A 30,000 Hz inductive heating system will be used to provide up to 250 kW of power to a 15 cm diameter SiC test section containing a packed bed of 3 cm graphite spheres. A SiC-to-Inconel 600 joint will use a conventional nickel/grafoil spiral wound gasket sandwiched between SiC and Inconel flanges. The loop system can provide up to 4.5 kg/s of salt flow at a head of 0.125 MPa and operate at a pressure just above atmospheric. Pebble Reynolds numbers of up to 2600 are possible with this configuration. A sump system is provided to drain and store the salt when not in use. Instrumentation on the loop will include pressure, temperature, and flow measurements, while the test section will be instrumented to provide pebble and FLiNaK temperatures.

  13. AN EXPERIMENT TO STUDY PEBBLE BED LIQUID-FLUORIDE-SALT HEAT TRANSFER

    SciTech Connect

    Yoder Jr, Graydon L; Aaron, Adam M; Heatherly, Dennis Wayne; Holcomb, David Eugene; Kisner, Roger A; McCarthy, Mike; Peretz, Fred J; Wilgen, John B; Wilson, Dane F

    2011-01-01

    A forced-convection liquid-fluoride-salt loop is being constructed at Oak Ridge National Laboratory (ORNL). This loop was designed as a versatile experimental facility capable of supporting general thermal/fluid/corrosion testing of liquid fluoride salts. The initial test configuration is designed to support the Pebble Bed Advanced High-Temperature Reactor and incorporates a test section designed to examine the heat transfer behavior of FLiNaK salt in a heated pebble bed. The loop is constructed of Inconel 600 and is capable of operating at up to 700oC. It contains a total of 72 kg of FLiNaK salt and uses an overhung impeller centrifugal sump pump that can provide FLiNaK flow at 4.5 kg/s with a head of 0.125 MPa. The test section is made of silicon carbide (SiC) and contains approximately 600 graphite spheres, 3 cm in diameter. The pebble bed is heated using a unique inductive technique. A forced induction air cooler removes the heat added to the pebble bed. The salt level within the loop is maintained by controlling an argon cover gas pressure. Salt purification is performed in batch mode by transferring the salt from the loop into a specially made nickel crucible system designed to remove oxygen, moisture and other salt impurities. Materials selection for the loop and test section material was informed by 3 months of Inconel 600 and SiC corrosion testing as well as tests examining subcomponent performance in the salt. Several SiC-to-Inconel 600 mechanical joint designs were considered before final salt and gas seals were chosen. Structural calculations of the SiC test section were performed to arrive at a satisfactory test section configuration. Several pump vendors provided potential loop pump designs; however, because of cost, the pump was designed and fabricated in-house. The pump includes a commercial rotating dry gas shaft seal to maintain loop cover gas inventory. The primary instrumentation on the loop includes temperature, pressure, and loop flow rate

  14. 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.

  15. An Experimental Test Facility to Support Development of the Fluoride Salt Cooled High Temperature Reactor

    SciTech Connect

    Yoder Jr, Graydon L; Aaron, Adam M; Cunningham, Richard Burns; Fugate, David L; Holcomb, David Eugene; Kisner, Roger A; Peretz, Fred J; Robb, Kevin R; Wilgen, John B; Wilson, Dane F

    2014-01-01

    The need for high-temperature (greater than 600 C) energy exchange and delivery systems is significantly increasing as the world strives to improve energy efficiency and develop alternatives to petroleum-based fuels. Liquid fluoride salts are one of the few energy transport fluids that have the capability of operating at high temperatures in combination with low system pressures. The Fluoride Salt-Cooled High-Temperature Reactor design uses fluoride salt to remove core heat and interface with a power conversion system. Although a significant amount of experimentation has been performed with these salts, specific aspects of this reactor concept will require experimental confirmation during the development process. The experimental facility described here has been constructed to support the development of the Fluoride Salt Cooled High Temperature Reactor concept. The facility is capable of operating at up to 700 C and incorporates a centrifugal pump to circulate FLiNaK salt through a removable test section. A unique inductive heating technique is used to apply heat to the test section, allowing heat transfer testing to be performed. An air-cooled heat exchanger removes added heat. Supporting loop infrastructure includes a pressure control system; trace heating system; and a complement of instrumentation to measure salt flow, temperatures, and pressures around the loop. The initial experiment is aimed at measuring fluoride salt heat transfer inside a heated pebble bed similar to that used for the core of the pebble bed advanced high-temperature reactor. This document describes the details of the loop design, auxiliary systems used to support the facility, the inductive heating system, and facility capabilities.

  16. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    SciTech Connect

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; Caja, Mario

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility of salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.

  17. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    SciTech Connect

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; Caja, Mario

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility of salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.

  18. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    DOE PAGES

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; ...

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility ofmore » salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.« less

  19. 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.

  20. Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zheng, Junyi; Lu, Yanling; Li, Zhijun; Zou, Yang; Yu, Xiaohan; Zhou, Xingtai

    2013-09-01

    Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (μ-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from μ-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys.

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

    PubMed

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

    2017-04-27

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

  2. Heat Transfer in Pebble-Bed Nuclear Reactor Cores Cooled by Fluoride Salts

    NASA Astrophysics Data System (ADS)

    Huddar, Lakshana Ravindranath

    underlining key distortions between the experimental and the prototypical conditions. This dissertation is broadly split into four parts. Firstly, the heat transfer phenomenology in the PB-FHR core was outlined. Although the viscous dissipation term and the thermal diffusion term (including thermal dispersion) were similar in magnitude, they were overshadowed by the advection term which was about 104 times bigger during normal operation and 105 times bigger during accident transients in which natural circulation becomes the main mode of fluid flow. Thus it is safe to neglect the viscous dissipation and the thermal diffusion terms in the PB-FHR core without a significant loss of accuracy. Secondly, separate effects tests (SET) were performed using simulant oils, and the results were compared to the prototypical conditions using flinak as the fluoride salt. The main purpose of these experiments was to study natural convection heat transfer and identify any distortions between the two cases. An isolated copper sphere was immersed in flinak and a parallel experiment was performed using simulant oil. A large discrepancy between the flinak and the oil was noted, due to distortions from assuming quasi-steady state conditions. A steady state experiment using a cylindrical heater immersed in oil was also performed, and the results compared to a similar experiment done at Oak Ridge National Laboratory (ORNL) using flinak. The Nusselt numbers matched within 10% for laminar flows. This supports the conclusion that natural convection similitude does exist for oils used in scaled experiments, allowing natural convection data to be used for for FHR and MSR modeling. This is important, due to the lack of significant experimental data showing natural convection in fluoride salts, so these SETs add to the overall understanding of their heat transfer properties. With the knowledge of the distortions between the oil and the salt, an experiment to measure heat transfer coefficients within a

  3. Fused Salt Electrodeposited TiB2 Coatings on High-Speed Steel Twist Drills

    DTIC Science & Technology

    1987-09-01

    this process was the ternary eutectic of lithium -, sodium-, and potassium-fluoride (FLINAK), melting at 842 0 F (454 0 C) with titanium and boron added...as fluotitanate (TiF6 ) and fluoborate (BF 4 ), respectively. The fused salt cell was operated under an inert gas enclosure ("dry box"). Four heavy

  4. Fluoride concentration of bottled water, tap water, and fluoridated salt from two communities in Mexico.

    PubMed

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

    2005-04-01

    To determine fluoride levels in bottled water, tap water, and fluoridated salt from two communities in Mexico. Stratified random collection of water and salt samples from Mexico City and Veracruz, Mexico for fluoride analysis. Samples were analysed using a combination fluoride ion-specific electrode. Results were compared using Student's t-test and mixed-model ANOVA. Water fluoride values were compared by type, community and collection area; salt fluoride values were compared by community and collection area. 197 tap water samples, 133 bottled water samples and 20 fluoridated salt samples were collected. The mean (+/- SD) fluoride content for all tap water was 0.20 +/- 0.17 microg F/g (ranging from 0.01 to 0.88 microg F/g) and 0.24 +/- 0.24 microg F/g for all bottled water (ranging from 0.01 to 2.80 microg F/g). This difference was not statistically significant. When results were analysed by city, the difference between tap water samples was statistically significant. Ten bottled water samples contained more than negligible fluoride (ranging from 0.7-2.8 microg F/g). Mean salt fluoride content was 230.0 +/- 49.8 microg F/g, which was within governmental regulation levels. Some water samples had amounts of fluoride exceeding the maximum recommended levels. Salt fluoride levels were within regulation limits. Monitoring of fluoride content of both bottled and tap water is strongly advised.

  5. The effect on human salivary fluoride concentration of consuming fluoridated salt-containing baked food items.

    PubMed

    Macpherson, L M; Stephen, K W

    2001-10-01

    Salt fluoridation is recognised world-wide as a proven and viable alternative means of consumer choice-related, community-based fluoridation where water fluoridation is either technically or politically impossible. However, as most salt consumed is contained within cooked food products, rather than sprinkled over prepared food at the table, the purpose of this study was to investigate the effects on salivary fluoride concentration of consuming baked food products prepared with 250 and 350 ppm fluoridated salt (as KF). Six food items were baked with (a) normal non-fluoridated salt, (b) 250 mg F/kg salt and (c) 350 mg F/kg salt. Eleven adult volunteers consumed these foodstuffs on separate occasions and salivary samples were collected for fluoride analyses before and at various time points (1-30 min) after eating. For most foodstuffs, small but significant increases in salivary fluoride concentration occurred for at least 5 min after ingestion of the fluoridated salt-containing items. Salivary fluoride concentrations peaked 1 or 2 min after eating, with highest values for the six test foods ranging from 0.16 to 0.25 ppm F, and from 0.18 to 0.44 ppm F for the 250 and 350 mg F/kg salt products, respectively. In all cases, salivary fluoride concentrations had returned to baseline by 20 min. The clinical significance of such small, short-term increases in salivary fluoride is uncertain, but the findings suggest that a more frequent intake of foods with fluoridated salt substituted for normal salt could help sustain slightly elevated salivary fluoride concentrations for more prolonged periods of the day, and might thus potentiate the cariostatic effects of saliva on tooth mineral.

  6. Protection of nuclear graphite toward liquid fluoride salt by isotropic pyrolytic carbon coating

    NASA Astrophysics Data System (ADS)

    He, Xiujie; Song, Jinliang; Xu, Li; Tan, Jie; Xia, Huihao; Zhang, Baoliang; He, Zhoutong; Gao, Lina; Zhou, Xingtai; Zhao, Mingwen; Zhu, Zhiyong; Bai, Shuo

    2013-11-01

    Infiltration studies were performed on uncoated nuclear graphite and isotropic pyrolytic carbon (PyC) coated graphite in molten FLiNaK salt at 650 °C under argon atmosphere at 1, 3 and 5 atm. Uncoated graphite shows weight gain more obviously than that of PyC coated graphite. Nuclear graphite with PyC coating exhibits excellent infiltration resistance in molten salt due to the small open porosity as conformed from scanning electron microscopy and mercury injection experiments.

  7. High Temperature Fluoride Salt Test Loop

    SciTech Connect

    Aaron, Adam M.; Cunningham, Richard Burns; Fugate, David L.; Holcomb, David Eugene; Kisner, Roger A.; Peretz, Fred J.; Robb, Kevin R.; Wilson, Dane F.; Yoder, Jr, Graydon L.

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  8. An Overview of Liquid Fluoride Salt Heat Transport Technology

    SciTech Connect

    Cetiner, Mustafa Sacit; Holcomb, David Eugene

    2010-01-01

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

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

    PubMed

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

    1995-09-01

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

  10. Liquid Fluoride Salt Experimentation Using a Small Natural Circulation Cell

    SciTech Connect

    Yoder Jr, Graydon L; Heatherly, Dennis Wayne; Williams, David F; Elkassabgi, Yousri M.; Caja, Joseph; Caja, Mario; Jordan, John; Salinas, Roberto

    2014-04-01

    A small molten fluoride salt experiment has been constructed and tested to develop experimental techniques for application in liquid fluoride salt systems. There were five major objectives in developing this test apparatus: Allow visual observation of the salt during testing (how can lighting be introduced, how can pictures be taken, what can be seen) Determine if IR photography can be used to examine components submerged in the salt Determine if the experimental configuration provides salt velocity sufficient for collection of corrosion data for future experimentation Determine if a laser Doppler velocimeter can be used to quantify salt velocities. Acquire natural circulation heat transfer data in fluoride salt at temperatures up to 700oC All of these objectives were successfully achieved during testing with the exception of the fourth: acquiring velocity data using the laser Doppler velocimeter. This paper describes the experiment and experimental techniques used, and presents data taken during natural circulation testing.

  11. 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

  12. Monitoring salt fluoridation programs through urinary excretion studies.

    PubMed

    Marthaler, Thomas M; Schulte, Andreas G

    2005-01-01

    This paper reviews problems associated with urinary collection for the estimation of fluoride exposure and recent findings in this context. After intake of a salted meal at noon, children aged 9 to 14 excreted on average 45 microgF/h. Morning and nocturnal excretions were only 16 microgF/h with the exception of those children who ate bread made with fluoridated salt (25 microF/h). Fluoride excretions in children consuming drinking water with 0.6 to 0.8 ppmF were similar, but the variations within the 24 h period were smaller. When it is not feasible to obtain reliable 24 h urinary collections, fairly precise extrapolations of 24 h excretions can be obtained from three separate collections lasting about 16 hours, which should cover morning, early afternoon and the whole night. Three- to six-year-old children benefitting from optimal fluoride supply through water or milk excreted approximately 0.35 to 0.40 mgF/24 h; this range seems to correspond to an optimal usage of fluorides. Studies on urinary fluoride excretion, like those on total fluoride intake, cannot be carried out on random samples. Due to the necessity of close cooperation of parents and children, such studies were done with "convenience" samples. In westernized countries with now low caries prevalence, intermittent high urinary excretions occur frequently. Possible sources are fluoride intake from concentrated oral care products (fluoride gels, fluoride chewing gums) or from dentifrices (containing 1000 to 1500 ppmF), mineral waters, industrial tea preparation or fluoride tablets (or other supplements). These problems do not affect the amount of fluoride in fingernail clippings which appear to be suitable for the routine monitoring of fluoride exposure.

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

    PubMed

    Wespi, H J; Bürgi, W

    1982-07-17

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

  14. [Ethical aspects of the fluoridation of water, salt, and milk].

    PubMed

    Rippe, K P

    2009-05-01

    The article discusses two ethical aspects of the fluoridation of water, salt, and milk. First, it considers whether fluoridation contradicts the right of self-determination. Second, it discusses the chances and risks of fluoridation. The answer to the first question depends on whether people can choose other options. Freedom of choice is not simply the right to choose between different options. It is a right which defends the moral integrity of persons. Nobody should be coerced to eat or drink something which he or she rejects morally. In the political sphere, personal rights of persons can be restricted if and only if it is necessary, if there is a public interest, and if the restriction of the right is reasonable. Regarding fluoridation, even in the best risk-chance scenario, some persons have to expect a net harm. Therefore, the reasoning in favor of fluoridation has to have a specific purpose. The proclaimed reasoning is that fluoridation will benefit the worst off and is therefore a demand of justice. But this argument fails as there are other options to benefit the worst off. Even in the best risk-chance scenario, only one option is morally permissible: the fluoridation of salt, which respects the freedom of choice.

  15. 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)

  16. Determination of thermal physical properties of alkali fluoride/carbonate eutectic molten salt

    NASA Astrophysics Data System (ADS)

    An, Xue-Hui; Cheng, Jin-Hui; Su, Tao; Zhang, Peng

    2017-06-01

    Molten salts used in high temperatures are more and more interested in the CSP for higher energy conversion efficiency. Thermal physical properties are the basic engineering data of thermal hydraulic calculation and safety analysis. Therefore, the thermophysical performances involving density, specific heat capacity, viscosity and thermal conductivity of FLiNaK, (LiNaK)2CO3 and LiF(NaK)2CO3 molten salts are experimentally determined and through comparison the general rules can be summarized. Density measurement was performed on the basis of Archimedes theory; specific heat capacity was measured using the DSC technique; viscosity was tested based on the rotating method; and the thermal conductivity was gained by laser flash method with combination of the density, specific heat capacity and thermal diffusivity through a formula. Finally, the energy storage capacity and figures of merit are calculated to evaluate their feasibility as TES and HFT media. The results show that FLiNaK has the largest energy storage capacity and best heat transfer performance, LiF(NaK)2CO3 is secondary, and (LiNaK)2CO3 has the smallest.

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

    PubMed

    Barker, Judith C; Guerra, Claudia; Gonzalez-Vargas, M Judy; Hoeft, Kristin S

    2016-01-01

    Compared to other population groups in the United States, caries (tooth decay) is a disproportionately prevalent disease among Latino populations, especially among low-income and rural sub-groups and children under five years of age. Fluoride is a primary preventive for caries. While water fluoridation is a major and effective public health means for delivering fluoride on a mass scale, it does not reach many rural areas or population groups such as Latinos who eschew drinking water from municipal sources. This study examines the acceptability to such groups of salt fluoridation, an alternate means of delivering fluoride long used on a global scale. An ethnographic study in California's rural Central Valley was performed. Thirty individual interviews and 5 focus groups (N = 61) were conducted in Spanish to investigate low-income Latino migrant caregivers' experiences, views and understandings of domestic salt, oral health, caries prevention and fluoride. Audio data were transcribed, translated, coded and thematically analyzed. Table salt was readily available and frequently consumed. Both adult and child daily sodium consumption was high. Despite a general feeling that it was good, and present in dentifrices or dietary supplements, most participants had little knowledge about fluoride. Concerns were raised about cardio-vascular and other possibly deleterious effects if an increase in salt consumption occurred because fluoridated salt was viewed as having 'extra' benefits. Once informed about fluoride's safety and role in caries prevention, most participants expressed willingness to use fluoridated salt, especially if it benefitted children. Reassurance about its safety and benefits, and demonstration of its taste, were important aspects of acceptance. Taste was paramount. Participants would not consume more fluoridated salt than their current salt as that would result in unpleasant changes in food flavor and taste. While salt fluoridation is acceptable, the

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

    PubMed

    Martínez-Mier, E A; Soto-Rojas, A E; Buckley, C M; Margineda, J; Zero, D T

    2009-12-01

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

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

    PubMed Central

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

    2010-01-01

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

  20. Corrosion Behavior of Alloys in Molten Fluoride Salts

    NASA Astrophysics Data System (ADS)

    Zheng, Guiqiu

    The molten fluoride salt-cooled high-temperature nuclear reactor (FHR) has been proposed as a candidate Generation IV nuclear reactor. This reactor combines the latest nuclear technology with the use of molten fluoride salt as coolant to significantly enhance safety and efficiency. However, an important challenge in FHR development is the corrosion of structural materials in high-temperature molten fluoride salt. The structural alloys' degradation, particularly in terms of chromium depletion, and the molten salt chemistry are key factors that impact the lifetime of nuclear reactors and the development of future FHR designs. In support of materials development for the FHR, the nickel base alloy of Hastelloy N and iron-chromium base alloy 316 stainless steel are being actively considered as critical structural alloys. Enriched 27LiF-BeF2 (named as FLiBe) is a promising coolant for the FHR because of its neutronic properties and heat transfer characteristics while operating at atmospheric pressure. In this study, the corrosion behavior of Ni-5Cr and Ni-20Cr binary model alloys, and Hastelloy N and 316 stainless steel in molten FLiBe with and without graphite were investigated through various microstructural analyses. Based on the understanding of the corrosion behavior and data of above four alloys in molten FLiBe, a long-term corrosion prediction model has been developed that is applicable specifically for these four materials in FLiBe at 700ºC. The model uses Cr concentration profile C(x, t) as a function of corrosion distance in the materials and duration fundamentally derived from the Fick's diffusion laws. This model was validated with reasonable accuracy for the four alloys by fitting the calculated profiles with experimental data and can be applied to evaluate corrosion attack depth over the long-term. The critical constant of the overall diffusion coefficient (Deff) in this model can be quickly calculated from the experimental measurement of alloys' weight

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

    PubMed Central

    Barker, Judith C.; Hoeft, Kristin S.

    2016-01-01

    Compared to other population groups in the United States, caries (tooth decay) is a disproportionately prevalent disease among Latino populations, especially among low-income and rural sub-groups and children under five years of age. Fluoride is a primary preventive for caries. While water fluoridation is a major and effective public health means for delivering fluoride on a mass scale, it does not reach many rural areas or population groups such as Latinos who eschew drinking water from municipal sources. This study examines the acceptability to such groups of salt fluoridation, an alternate means of delivering fluoride long used on a global scale. An ethnographic study in California’s rural Central Valley was performed. Thirty individual interviews and 5 focus groups (N = 61) were conducted in Spanish to investigate low-income Latino migrant caregivers’ experiences, views and understandings of domestic salt, oral health, caries prevention and fluoride. Audio data were transcribed, translated, coded and thematically analyzed. Table salt was readily available and frequently consumed. Both adult and child daily sodium consumption was high. Despite a general feeling that it was good, and present in dentifrices or dietary supplements, most participants had little knowledge about fluoride. Concerns were raised about cardio-vascular and other possibly deleterious effects if an increase in salt consumption occurred because fluoridated salt was viewed as having ‘extra’ benefits. Once informed about fluoride’s safety and role in caries prevention, most participants expressed willingness to use fluoridated salt, especially if it benefitted children. Reassurance about its safety and benefits, and demonstration of its taste, were important aspects of acceptance. Taste was paramount. Participants would not consume more fluoridated salt than their current salt as that would result in unpleasant changes in food flavor and taste. While salt fluoridation is acceptable

  2. Fluoride Salt-Cooled High-Temperature Reactor Development Roadmap

    SciTech Connect

    Holcomb, David Eugene; Flanagan, George F; Mays, Gary T; Pointer, William David; Robb, Kevin R; Yoder Jr, Graydon L

    2014-01-01

    Fluoride salt-cooled high-temperature reactors (FHRs) are an emerging reactor class with potentially advantageous performance characteristics and fully passive safety. This paper provides an overview of a technology development pathway for expeditious commercial deployment of first-generation FHRs. The paper describes the principal remaining FHR technology challenges and the development path needed to address the challenges. First-generation FHRs do not appear to require any technology breakthroughs, but will require significant technology development and demonstration. FHRs are currently entering early phase engineering development. As such, the development roadmap is not as technically detailed or specific as would be the case for a more mature reactor class. The higher cost of fuel and coolant; the lack of an approved licensing framework; the lack of qualified, salt-compatible structural materials; and the potential for tritium release into the environment are the most obvious issues that remain to be resolved.

  3. Effects of fluoride tablets on caries and fluorosis occurrence among 6- to 9-year olds using fluoridated salt.

    PubMed

    Meyer-Lueckel, H; Grundmann, E; Stang, A

    2010-08-01

    The aim of this retrospective cohort study was to investigate the association between the use of fluoride tablets among users of fluoridated salt and the occurrence of caries and fluorosis. We examined 583 school children aged 6-9 years in Berlin, Germany for caries-status (modified defs > or = 1; d(3)-level) and fluorosis occurrence on central incisors (TSIF > or = 1). Parents completed questionnaires about several sociodemographic and oral health related factors of the previous years. To adjust for confounding, we used log-risk regression and estimated relative risks (RR) and 95% confidence intervals. The mean modified defs was 3.2 (SD = 5.9) and 58% children were caries-free. Twenty-two per cent of the children revealed mild fluorosis (TSIF 1 and 2). Length of fluoride tablet use was inversely associated (adjusted for age and SES) with caries-status: 2-4 years: RR = 0.8, 95%CI: 0.7-1.0, > or =5 years: RR = 0.5, 95%CI 0.3-0.7 (reference: 0-1 year use). This inverse association could mainly be observed in children who consumed fluoridated salt as well. Relative risks for mild fluorosis were 1.8 (95%CI: 1.1-2.9) and 2.7 (95%CI: 1.6-4.5) for fluoride tablet use of 2-4 years and > or =5 years, respectively compared with 0-1 year use. Fluoride tablets seem to be effective in reducing the occurrence of caries in children with low caries levels in particular among those using fluoridated salt as well. However, fluoride tablets increase the occurrence of mild fluorosis in permanent incisors.

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

    DOEpatents

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

    1977-01-01

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

  5. Densities of some molten fluoride salt mixtures suitable for heat storage in space power applications

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1988-01-01

    Liquid densities were determined for a number of fluoride salt mixtures suitable for heat storage in space power applications, using a procedure that consisted of measuring the loss of weight of an inert bob in the melt. The density apparatus was calibrated with pure LiF and NaF at different temperatures. Density data for safe binary and ternary fluoride salt eutectics and congruently melting intermediate compounds are presented. In addition, a comparison was made between the volumetric heat storage capacity of different salt mixtures.

  6. Densities of some molten fluoride salt mixtures suitable for heat storage in space power applications

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1988-01-01

    Liquid densities were determined for a number of fluoride salt mixtures suitable for heat storage in space power applications, using a procedure that consisted of measuring the loss of weight of an inert bob in the melt. The density apparatus was calibrated with pure LiF and NaF at different temperatures. Density data for safe binary and ternary fluoride salt eutectics and congruently melting intermediate compounds are presented. In addition, a comparison was made between the volumetric heat storage capacity of different salt mixtures.

  7. Assessment of the Use of Nitrogen Trifluoride for Purifying Coolant and Heat Transfer Salts in the Fluoride Salt-Cooled High-Temperature Reactor

    SciTech Connect

    Scheele, Randall D.; Casella, Andrew M.

    2010-09-28

    This report provides an assessment of the use of nitrogen trifluoride for removing oxide and water-caused contaminants in the fluoride salts that will be used as coolants in a molten salt cooled reactor.

  8. Mesocarbon microbead based graphite for spherical fuel element to inhibit the infiltration of liquid fluoride salt in molten salt reactor

    NASA Astrophysics Data System (ADS)

    Zhong, Yajuan; Zhang, Junpeng; Lin, Jun; Xu, Liujun; Zhang, Feng; Xu, Hongxia; Chen, Yu; Jiang, Haitao; Li, Ziwei; Zhu, Zhiyong; Guo, Quangui

    2017-07-01

    Mesocarbon microbeads (MCMB) and quasi-isostatic pressing method were used to prepare MCMB based graphite (MG) for spherical fuel element to inhibit the infiltration of liquid fluoride salt in molten salt reactor (MSR). Characteristics of mercury infiltration and molten salt infiltration in MG were investigated and compared with A3-3 (graphite for spherical fuel element in high temperature gas cooled reactor) to identify the infiltration behaviors. The results indicated that MG had a low porosity about 14%, and an average pore diameter of 96 nm. Fluoride salt occupation of A3-3 (average pore diameter was 760 nm) was 10 wt% under 6.5 atm, whereas salt gain did not infiltrate in MG even up to 6.5 atm. It demonstrated that MG could inhibit the infiltration of liquid fluoride salt effectively. Coefficient of thermal expansion (CTE) of MG lies in 6.01 × 10-6 K-1 (α∥) and 6.15 × 10-6 K-1 (α⊥) at the temperature range of 25-700 °C. The anisotropy factor of MG calculated by CTE maintained below 1.02, which could meet the requirement of the spherical fuel element (below 1.30). The constant isotropic property of MG is beneficial for the integrity and safety of the graphite used in the spherical fuel element for a MSR.

  9. 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.

  10. Fluorosis and dental caries in Mexican schoolchildren residing in areas with different water fluoride concentrations and receiving fluoridated salt.

    PubMed

    García-Pérez, A; Irigoyen-Camacho, M E; Borges-Yáñez, A

    2013-01-01

    To explore the association between fluoride in drinking water and the prevalence and severity of fluorosis and dental caries in children living in communities receiving fluoridated salt. Participants were schoolchildren (n = 457) living in two rural areas of the State of Morelos, Mexico, where the water fluoride concentration was 0.70 or 1.50 ppm. Dental caries status was assessed using Pitts' criteria. Lesions that were classified as D3 (decayed) were identified to determine the decayed, missing, and filled teeth index (D3MFT). Fluorosis was assessed using the Thylstrup-Fejerskov Index (TFI). Information regarding drinking water source and oral hygiene practices (tooth brushing frequency, dentifrice use, and oral hygiene index) was obtained. The prevalence of fluorosis (TFI ≥1) in communities with 0.70 and 1.50 ppm water fluoride was 39.4 and 60.5% (p = 0.014), respectively, while the prevalence of more severe forms (TFI ≥4) was 7.9 and 25.5% (p < 0.001), respectively. The mean D3MFT was 0.49 (±1.01) in the 0.70 ppm community and 0.61 (±1.47) in the 1.50 ppm community (p = 0.349). A logistic regression model for caries (D3 >1) showed that higher fluorosis categories (TFI 5-6 OR = 6.81, p = 0.001) were associated with higher caries experience, adjusted by age, number of teeth present, tooth brushing frequency, bottled water use, and natural water fluoride concentration. The prevalence of fluorosis was associated with the water fluoride concentration. Fluorosis at moderate and severe levels was associated with a higher prevalence of dental caries, compared with lesser degrees of fluorosis. The impact of dental fluorosis should be considered in dental public health programs. Copyright © 2013 S. Karger AG, Basel.

  11. Disposition of the fluoride fuel and flush salts from the Molten Salt Reactor experiment at Oak Ridge National Laboratory

    SciTech Connect

    Peretz, F.J.

    1996-03-01

    The Molten Salt Reactor Experiment (MSRE) is an 8 MW reactor that was operated at Oak Ridge National Laboratory (ORNL) from 1965 through 1969. The reactor used a unique liquid salt fuel, composed of a mixture of LIF, BeF{sub 2}, ZrF{sub 4}, and UF{sub 4}, and operated at temperatures above 600{degrees}C. The primary fuel salt circulation system consisted of the reactor vessel, a single fuel salt pump, and a single primary heat exchanger. Heat was transferred from the fuel salt to a coolant salt circuit in the primary heat exchanger. The coolant salt was similar to the fuel salt, except that it contains only LiF (66%) and BeF, (34%). The coolant salt passed from the primary heat exchanger to an air-cooled radiator and a coolant salt pump, and then returned to the primary heat exchanger. Each of the salt loops was provided with drain tanks, located such that the salt could be drained out of either circuit by gravity. A single drain tank was provided for the non-radioactive coolant salt. Two drain tanks were provided for the fuel salt. Since the fuel salt contained radioactive fuel, fission products, and activation products, and since the reactor was designed such that the fuel salt could be drained immediately into the drain tanks in the event of a problem in the fuel salt loop, the fuel salt drain tanks were provided with a system to remove the heat generated by radioactive decay. A third drain tank connected to the fuel salt loop was provided for a batch of flush salt. This batch of salt, similar in composition to the coolant salt, was used to condition the fuel salt loop after it had been exposed to air and to flush the fuel salt loop of residual fuel salt prior to accessing the reactor circuit for maintenance or experimental activities. This report discusses the disposition of the fluoride fuel and flush salt.

  12. Fluoride

    MedlinePlus

    ... by teeth and helps to strengthen teeth, resist acid, and block the cavity-forming action of bacteria. Fluoride usually is prescribed for children and adults whose homes have water that is not fluoridated (already has fluoride added). ...

  13. Materials corrosion in molten LiF-NaF-KF eutectic salt under different reduction-oxidation conditions

    SciTech Connect

    Sellers, R. S.; Cheng, W. J.; Anderson, M. H.; Sridharan, K.; Wang, C. J.; Allen, T. R.

    2012-07-01

    Molten fluoride salts such as FLiNaK (LiF-NaF-KF: 46.5-11.5-42 mol %) have been proposed for use as secondary reactor coolants, media for transfer of high temperature process heat from nuclear reactors to chemical plants, and for concentrated solar power thermal energy storage. In molten fluoride salts, passive oxide films are chemically unstable, and corrosion is driven largely by the thermodynamically driven dissolution of alloying elements into the molten salt environment. Two alloys, Hastelloy{sup R} N and 316L stainless steel were exposed to molten FLiNaK salt in a 316L stainless steel crucible under argon cover gas for 1000 hours at 850 deg. C. Graphite was present in some of the crucibles with the goal of studying corrosion behavior of relevant reactor material combinations. In addition, a technique to reduce alloy corrosion through modification of the reduction-oxidation state was tested by the inclusion of zirconium to the system. Corrosion of 316L stainless steel was noted to occur primarily through surface depletion of chromium, an effect that was enhanced by the presence of graphite. Hastelloy{sup R} N experienced weight gain through electrochemical plating of corrosion products derived from the 316L stainless steel crucible. In the presence of zirconium, both alloys gained weight through plating of zirconium and as a result formed intermetallic layers. (authors)

  14. 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

  15. Engineering Database of Liquid Salt Thermophysical and Thermochemical Properties

    SciTech Connect

    Manohar S. Sohal; Matthias A. Ebner; Piyush Sabharwall; Phil Sharpe

    2010-03-01

    The purpose of this report is to provide a review of thermodynamic and thermophysical properties of candidate molten salt coolants, which may be used as a primary coolant within a nuclear reactor or heat transport medium from the Next Generation Nuclear Plant (NGNP) to a processing plant, for example, a hydrogen-production plant. Thermodynamic properties of four types of molten salts, including LiF-BeF2 (67 and 33 mol%, respectively; also known as FLiBe), LiF-NaF-KF (46.5, 11.5, and 52 mol%, also known as FLiNaK), and KCl-MgCl2 (67 and 33 mol%), and sodium nitrate-sodium nitrite-potassium nitrate (NaNO3–NaNO2–KNO3, (7-49-44 or 7-40-53 mol%) have been investigated. Limitations of existing correlations to predict density, viscosity, specific heat capacity, surface tension, and thermal conductivity, were identified. The impact of thermodynamic properties on the heat transfer, especially Nusselt number was also discussed. Stability of the molten salts with structural alloys and their compatibility with the structural alloys was studied. Nickel and alloys with dense Ni coatings are effectively inert to corrosion in fluorides but not so in chlorides. Of the chromium containing alloys, Hastelloy N appears to have the best corrosion resistance in fluorides, while Haynes 230 was most resistant in chloride. In general, alloys with increasing carbon and chromium content are increasingly subject to corrosion by the fluoride salts FLiBe and FLiNaK, due to attack and dissolution of the intergranular chromium carbide. Future research to obtain needed information was identified.

  16. Preparation of fluoride-substituted hydroxyapatite by a molten salt synthesis route.

    PubMed

    Zhang, Hui Gang; Zhu, Qingshan

    2006-08-01

    Fluoride-substituted hydroxyapatite (FHAp) with high thermal and morphologic stability was successfully prepared by a molten salt synthesis route. XRD patterns and FTIR spectra identified the synthesized powders as FHAp solid solution. The FHAp obtained with potassium sulfate as the flux showed the rod-like morphology without detectable decomposition up to 1300 degrees Celsius and the flux, sodium sulfate, led to the spheriodal FHAp. After investigating the effects of salt species on the FHAp morphologies, it was found that solubility was not the exclusive factor, which affected the morphological development of apatite powders, and the cations of molten salt species also played an important role.

  17. 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.

  18. 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.

  19. Molten fluoride salts incorporation into pristine and ion-modified carbon allotropes and metallic foils

    NASA Astrophysics Data System (ADS)

    Vacík, J.; Hnatowicz, V.; Ĉervená, J.; Mach, R.; Peka, I.

    1999-01-01

    Incorporation of molten fluoride salts into different carbon allotropes (glassy carbon, pyrolytic graphite etc.) and metallic foils (Ni, Ti, etc.), pristine and ion- treated substances, has been studied using non-destructive, depth sensitive nuclear analytical methods—Neutron Depth Profiling (NDP) and Rutherford Backscattering (RBS). Strong interaction between the molten LiF and LiF+KF+NaF salts and the tested materials was found. The results are of great interest for accelerator driven transmutation technology (ADTT) which is a promising way towards effective liquidation of nuclear wastes.

  20. Preparation and characterization of graphite fluorometallate salts and graphite fluorides by chemical and electrochemical methods

    SciTech Connect

    Lerner, M.M.

    1988-09-01

    Graphite intercalation compounds of main-group metal fluorides are prepared utilizing Cl/sub 2/ as an oxidizing agent. The action of Cl/sub 2/ with GeF/sub 4/ and Cl/sub 2//HF with either PF/sub 5/ or BF/sub 3/ on graphite produces fluorometallate salts. The relationship between the calculated enthalpy change for the reduction half-reaction and degree of intercalation is discussed. The electrochemical oxidation of graphite in 49% aqueous HF generates, at the oxidation limit, a 2nd stage graphite fluoride with a charge on carbon of C/sub 10/minus/14//sup /plus//. The fully-oxidized product is a 2nd stage analog of the planar-sheet graphite fluorides produced by the chemical or electrochemical fluorination of graphite in liquid anhydrous hydrogen fluoride (AHF). The fluorometallate salts prepared by electrochemical oxidation of graphite in an AHF/alkali metal fluorometallate salt (M = As, P, B, Sn) electrolyte are examined. The chemical fluorination of 2nd- and 3rd-stage C/sub x/AsF/sub 6/ salts with AHF/F/sub 2/ at ambient temperature produces a planar-sheet graphite fluoride phase with a C/F ratio as low as 1.3 along with a C/sub x/AsF/sub 6/ phase. The reaction of graphite with AHF/SnF/sub 4//F/sub 2/ results in the rapid disappearance of SnF/sub 4/, F/sub 2/ uptake, and color change of the solid from grey to blue-black. Graphite reacts with AHF/K/sub 2/MnF/sub 6/ in a stoichiometric ratio of at least 1 Mn for 6 C to produce MnF/sub 3/ and a C/sub x/F phase. The reaction of excess PF/sub 5/ with a well-evacuated C/sub x/BF/sub 4/ /center dot/ deltaBF/sub 3/ salt yields partial displacement of BF/sub 3/. When PF/sub 5/ /plus/ HF are employed, no BF/sub 3/ is displaced from the fluoroborate salt. 21 refs., 15 figs., 18 tabs.

  1. Considerations of Alloy N for Fluoride Salt-Cooled High-Temperature Reactor Applications

    SciTech Connect

    Ren, Weiju; Muralidharan, Govindarajan; Wilson, Dane F; Holcomb, David Eugene

    2011-01-01

    Fluoride Salt-Cooled High-Temperature Reactors (FHRs) are a promising new class of thermal-spectrum nuclear reactors. The reactor structural materials must possess high-temperature strength and chemical compatibility with the liquid fluoride salt as well as with a power cycle fluid such as supercritical water while remaining resistant to residual air within the containment. Alloy N was developed for use with liquid fluoride salts and it possesses adequate strength and chemical compatibility up to about 700 C. A distinctive property of FHRs is that their maximum allowable coolant temperature is restricted by their structural alloy maximum service temperature. As the reactor thermal efficiency directly increases with the maximum coolant temperature, higher temperature resistant alloys are strongly desired. This paper reviews the current status of Alloy N and its relevance to FHRs including its design principles, development history, high temperature strength, environmental resistance, metallurgical stability, component manufacturability, ASME codification status, and reactor service requirements. The review will identify issues and provide guidance for improving the alloy properties or implementing engineering solutions.

  2. 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.

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

    PubMed

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

    2016-09-01

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

  4. Intergranular fracture of lithium fluoride-22 percent calcium fluoride hypereutectic salt at 800 K

    NASA Technical Reports Server (NTRS)

    Raj, Subramanium V.; Whittenberger, J. Daniel

    1990-01-01

    Substantial strain-hardening was noted during the initial stages of deformation in constant-velocity compression tests conducted on as-cast samples of the LiF-22 mol pct CaF2 hypereutectic salt at 800 K. The deformed specimens exhibited extensive grain-boundary cracking and cavitation, suggesting that such cracking, in conjunction with interfacial sliding, is important for cavity nucleation at grain boundaries and at the LiF-CaF2 interfaces. Cavity growth and interlinkage occur through the preferential failure of the weaker LiF phase.

  5. Intergranular fracture of lithium fluoride-22 percent calcium fluoride hypereutectic salt at 800 K

    NASA Technical Reports Server (NTRS)

    Raj, Subramanium V.; Whittenberger, J. Daniel

    1990-01-01

    Substantial strain-hardening was noted during the initial stages of deformation in constant-velocity compression tests conducted on as-cast samples of the LiF-22 mol pct CaF2 hypereutectic salt at 800 K. The deformed specimens exhibited extensive grain-boundary cracking and cavitation, suggesting that such cracking, in conjunction with interfacial sliding, is important for cavity nucleation at grain boundaries and at the LiF-CaF2 interfaces. Cavity growth and interlinkage occur through the preferential failure of the weaker LiF phase.

  6. Production and release of ISOL beams from molten fluoride salt targets

    NASA Astrophysics Data System (ADS)

    Mendonca, T. M.; Hodak, R.; Ghetta, V.; Allibert, M.; Heuer, D.; Noah, E.; Cimmino, S.; Delonca, M.; Gottberg, A.; Kronberger, M.; Ramos, J. P.; Seiffert, C.; Stora, T.

    2014-06-01

    In the framework of the Beta Beams project, a molten fluoride target has been proposed for the production of the required 101318Ne/s. The production and extraction of such rates are predicted to be possible on a circulating molten salt with 160 MeV proton beams at close to 1 MW power. As a most important step to validate the concept, a prototype has been designed and investigated at CERN-ISOLDE using a static target unit. The target material consisted of a binary fluoride system, NaF:LiF (39:61 mol.%), with melting point at 649 °C. The production of Ne beams has been monitored as a function of the target temperature and proton beam intensity. The prototype development and the results of the first online tests with 1.4 GeV proton beam are presented in this paper.

  7. The determination of UO/sub 2/ and UF/sub 4/ in fused fluoride salts

    SciTech Connect

    Batiste, D.J.; Lee, D.A.

    1989-01-01

    The determination of uranium oxide solubilities in fused fluoride salts is important in the electrolytic preparation of uranium metal. This project was initiated to develop a method for the determination of UO/sub 2/ separately from UF/sub 4/ in UF/sub 4/-CaF/sub 2/-LiF fused salts. Previous methods used for the determination of UO/sub 2/ in fused fluoride salts involved inert gas fusions where oxygen was liberated as CO/sub 2/, and hydrofluorination where oxygen was released as H/sub 2/O; but the special equipment used for these procedures was no longer available. These methods assumed that all of the oxygen liberated was due to UO/sub 2/ and does not consider impurities from reagents and other oxygen sources that amount to a bias of approximately 0.3 wt %. This titrimetric method eliminates the bias by selectively extracting the UF/sub 4/ with a Na/sub 2/EDTA-H/sub 3/BO/sub 3/ solution. The remaining uranium oxide residue is treated and titrated gravimetrically to a potentiometric endpoint with NBS standard K/sub 2/Cr/sub 2/O/sub 7/. An aliquot of the Na/sub 2/EDTA-H/sub 3/BO/sub 3/ extract is also titrated gravimetrically to a potentiometric endpoint, this uranium component is determined and calculated as UF/sub 4/. 4 refs., 2 figs., 2 tabs.

  8. The prevalence of dental fluorosis in relation to water or salt fluoridation and reported use of fluoride toothpaste in school-age children.

    PubMed

    Sagheri, D; McLoughlin, J; Clarkson, J J

    2007-03-01

    To compare prevalence of dental fluorosis (DF) in permanent teeth in children whose domestic water supply was fluoridated since birth with that in a community where fluoridated salt was available. A second aim was to analyse the relationship between DF prevalence and reported use of fluoride toothpaste in early childhood. Cross-sectional study. A representative, random sample of 12-year-old children was examined in water fluoridated Dublin (Ireland) and non-water fluoridated Freiburg (Germany), where fluoridated salt was available. DF was recorded using the Dean's Index. The child's early experience of toothpaste use was recorded using a questionnaire. 377 children in Dublin and 322 children in Freiburg were examined. In Dublin 11.7% of the whole sample had a 'Questionable' level of DF, 9.8% had 'Very Mild', 3.7% had 'Mild' and 0.3% had 'Moderate' fluorosis. The corresponding percentages in Freiburg for all children were 10.9%, 4.0%, 3.4% and 0%. The results suggest that children in Dublin started brushing their teeth at an older age than in Freiburg, but no difference in DF levels was found between 'early' and 'late' users. Fisher's test revealed that the difference in DF levels between the two populations was statistically significant (p=0.03). The prevalence of aesthetically important DF ('Mild' and 'Moderate') was low and similar in both communities and considerably lower than the expected level at water fluoridation concentrations of 1 ppm. However, the prevalence of 'Very Mild' fluorosis was twice as frequent in Dublin than in Freiburg.

  9. The current status of fluoride salt cooled high temperature reactor (FHR) technology and its overlap with HIF target chamber concepts

    NASA Astrophysics Data System (ADS)

    Scarlat, Raluca O.; Peterson, Per F.

    2014-01-01

    The fluoride salt cooled high temperature reactor (FHR) is a class of fission reactor designs that use liquid fluoride salt coolant, TRISO coated particle fuel, and graphite moderator. Heavy ion fusion (HIF) can likewise make use of liquid fluoride salts, to create thick or thin liquid layers to protect structures in the target chamber from ablation by target X-rays and damage from fusion neutron irradiation. This presentation summarizes ongoing work in support of design development and safety analysis of FHR systems. Development work for fluoride salt systems with application to both FHR and HIF includes thermal-hydraulic modeling and experimentation, salt chemistry control, tritium management, salt corrosion of metallic alloys, and development of major components (e.g., pumps, heat exchangers) and gas-Brayton cycle power conversion systems. In support of FHR development, a thermal-hydraulic experimental test bay for separate effects (SETs) and integral effect tests (IETs) was built at UC Berkeley, and a second IET facility is under design. The experiments investigate heat transfer and fluid dynamics and they make use of oils as simulant fluids at reduced scale, temperature, and power of the prototypical salt-cooled system. With direct application to HIF, vortex tube flow was investigated in scaled experiments with mineral oil. Liquid jets response to impulse loading was likewise studied using water as a simulant fluid. A set of four workshops engaging industry and national laboratory experts were completed in 2012, with the goal of developing a technology pathway to the design and licensing of a commercial FHR. The pathway will include experimental and modeling efforts at universities and national laboratories, requirements for a component test facility for reliability testing of fluoride salt equipment at prototypical conditions, requirements for an FHR test reactor, and development of a pre-conceptual design for a commercial reactor.

  10. Estimated heats of fusion of fluoride salt mixtures suitable for thermal energy storage applications

    NASA Technical Reports Server (NTRS)

    Misra, A. K.; Whittenberger, J. D.

    1986-01-01

    The heats of fusion of several fluoride salt mixtures with melting points greater than 973 K were estimated from a coupled analysis of the available thermodynamic data and phase diagrams. Simple binary eutectic systems with and without terminal solid solutions, binary eutectics with congruent melting intermediate phases, and ternary eutectic systems were considered. Several combinations of salts were identified, most notable the eutectics LiF-22CaF2 and NaF-60MgF2 which melt at 1039 and 1273 K respectively which posses relatively high heats of fusion/gm (greater than 0.7 kJ/g). Such systems would seemingly be ideal candidates for the light weight, high energy storage media required by the thermal energy storage unit in advanced solar dynamic power systems envisioned for the future space missions.

  11. Fluoride Salt-Cooled High-Temperature Reactor Technology Development and Demonstration Roadmap

    SciTech Connect

    Holcomb, David Eugene; Flanagan, George F; Mays, Gary T; Pointer, William David; Robb, Kevin R; Yoder Jr, Graydon L

    2013-11-01

    Fluoride salt-cooled High-temperature Reactors (FHRs) are an emerging reactor class with potentially advantageous performance characteristics, and fully passive safety. This roadmap describes the principal remaining FHR technology challenges and the development path needed to address the challenges. This roadmap also provides an integrated overview of the current status of the broad set of technologies necessary to design, evaluate, license, construct, operate, and maintain FHRs. First-generation FHRs will not require any technology breakthroughs, but do require significant concept development, system integration, and technology maturation. FHRs are currently entering early phase engineering development. As such, this roadmap is not as technically detailed or specific as would be the case for a more mature reactor class. The higher cost of fuel and coolant, the lack of an approved licensing framework, the lack of qualified, salt-compatible structural materials, and the potential for tritium release into the environment are the most obvious issues that remain to be resolved.

  12. Preconceptual design of a fluoride high temperature salt-cooled engineering demonstration reactor: Motivation and overview

    SciTech Connect

    Qualls, A. Louis; Betzler, Benjamin R.; Brown, Nicholas R.; Carbajo, Juan J.; Greenwood, M. Scott; Hale, Richard; Harrison, Thomas J.; Powers, Jeffrey J.; Robb, Kevin R.; Terrell, Jerry; Wysocki, Aaron J.; Gehin, Jess C.; Worrall, Andrew

    2016-12-21

    Engineering demonstration reactors are nuclear reactors built to establish proof of concept for technology options that have never been built. Examples of engineering demonstration reactors include Peach Bottom 1 for high temperature gas-cooled reactors (HTGRs) and Experimental Breeder Reactor-II (EBR-II) for sodium-cooled fast reactors. Historically, engineering demonstrations have played a vital role in advancing the technology readiness level of reactor technologies. Our paper details a preconceptual design for a fluoride salt-cooled engineering demonstration reactor. The fluoride salt-cooled high-temperature reactor (FHR) demonstration reactor (DR) is a concept for a salt-cooled reactor with 100 megawatts of thermal output (MWt). It would use tristructural-isotropic (TRISO) particle fuel within prismatic graphite blocks. FLiBe (2 7LiF-BeF2) is the reference primary coolant. The FHR DR is designed to be small, simple, and affordable. Development of the FHR DR is a necessary intermediate step to enable near-term commercial FHRs. The design philosophy of the FHR DR was focused on safety, near-term deployment, and flexibility. Lower risk technologies are purposely included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated as an engineering demonstration with minimal risk and cost. These technologies include TRISO particle fuel, replaceable core structures, and consistent structural material selection for core structures and the primary and intermediate loops, and tube-and-shell primary-to-intermediate heat exchangers. Important capabilities to be demonstrated by building and operating the FHR DR include fabrication and operation of high temperature reactors; heat exchanger performance (including passive decay heat removal); pump performance; and reactivity control; salt chemistry control to maximize vessel life; tritium management; core design methodologies; salt procurement, handling, maintenance and ultimate disposal. It

  13. Preconceptual design of a fluoride high temperature salt-cooled engineering demonstration reactor: Motivation and overview

    DOE PAGES

    Qualls, A. Louis; Betzler, Benjamin R.; Brown, Nicholas R.; ...

    2016-12-21

    Engineering demonstration reactors are nuclear reactors built to establish proof of concept for technology options that have never been built. Examples of engineering demonstration reactors include Peach Bottom 1 for high temperature gas-cooled reactors (HTGRs) and Experimental Breeder Reactor-II (EBR-II) for sodium-cooled fast reactors. Historically, engineering demonstrations have played a vital role in advancing the technology readiness level of reactor technologies. Our paper details a preconceptual design for a fluoride salt-cooled engineering demonstration reactor. The fluoride salt-cooled high-temperature reactor (FHR) demonstration reactor (DR) is a concept for a salt-cooled reactor with 100 megawatts of thermal output (MWt). It would usemore » tristructural-isotropic (TRISO) particle fuel within prismatic graphite blocks. FLiBe (2 7LiF-BeF2) is the reference primary coolant. The FHR DR is designed to be small, simple, and affordable. Development of the FHR DR is a necessary intermediate step to enable near-term commercial FHRs. The design philosophy of the FHR DR was focused on safety, near-term deployment, and flexibility. Lower risk technologies are purposely included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated as an engineering demonstration with minimal risk and cost. These technologies include TRISO particle fuel, replaceable core structures, and consistent structural material selection for core structures and the primary and intermediate loops, and tube-and-shell primary-to-intermediate heat exchangers. Important capabilities to be demonstrated by building and operating the FHR DR include fabrication and operation of high temperature reactors; heat exchanger performance (including passive decay heat removal); pump performance; and reactivity control; salt chemistry control to maximize vessel life; tritium management; core design methodologies; salt procurement, handling, maintenance and ultimate

  14. 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.

  15. Heat Transfer Salts for Nuclear Reactor Systems - Chemistry Control, Corrosion Mitigation, and Modeling

    SciTech Connect

    Anderson, Mark; Sridharan, Kumar; Morgan, Dane; Peterson, Per; Calderoni, Pattrick; Scheele, Randall; Casekka, Andrew; McNamara, Bruce

    2015-01-22

    -evaluate thermophysical properties of flibe and flinak. Pacific Northwest National Laboratories has focused on evaluating the fluorinating gas nitrogen trifluoride as a potential salt purification agent. Work there was performed on removing hydroxides and oxides from flinak salt under controlled conditions. Lastly, the University of California Berkeley has spent considerable time designing and simulating reactor components with fluoride salts at high temperatures. Despite the hurdles presented by the innate chemical hazards, considerable progress has been made. The stage has been set to perform new research on salt chemical control which could advance the fluoride salt cooled reactor concept towards commercialization. What were previously thought of as chemical undesirable, but nuclear certified, alloys have been shown to be theoretically compatible with fluoride salts at high temperatures. This preliminary report has been prepared to communicate the construction of the basic infrastructure required for flibe, as well as suggest original research to performed at the University of Wisconsin. Simultaneously, the contents of this report can serve as a detailed, but introductory guide to allow anyone to learn the fundamentals of chemistry, engineering, and safety required to work with flibe salt.

  16. Fluoride pollution in a salt marsh: movement between soil, vegetation, and sheep

    SciTech Connect

    Baars, A.J.; van Beek, H.; Spierenburg, T.J.; de Graaf, G.J.; Beeftink, W.G.; Nieuwenhuize, J.; Boom, J.; Pekelder, J.J.

    1987-12-01

    The river Scheldt (southwestern part of The Netherlands) is responsible for a considerable pollution of its estuary with organic and inorganic waste, which becomes manifest particularly in the salt marshes. Of these marshes, the 3400 ha nature reserve of the Saeftinge sale marsh constitutes a representative example of such a valuable tidal brackish ecosystem. This marsh is partly grazed by sheep, thus contributing to its original character and assisting in the preservation of the local flora and fauna. Preceding reports indicated a significant degree of contamination with heavy metals, which were shown to enter food chains. The present study focuses on fluoride, an environmental contaminant known to be spread by water and air, and, although assumed to be beneficial in small quantities, a potential threat for plants and animals, particularly herbivores.

  17. Preliminary requirements for a Fluoride Salt-Cooled High-Temperature Test Reactor (FHTR)

    SciTech Connect

    Massie, M.; Forsberg, C.; Forget, B.; Hu, L. W.

    2012-07-01

    A Fluoride Salt-Cooled High-Temperature Test Reactor (FHTR) design is being developed at MIT to provide the first demonstration and test of a salt-cooled reactor using high-temperature fuel. The first step is to define the requirements. The top level requirements are (1) provide the confidence that a larger demonstration reactor is warranted and (2) develop the necessary data for a larger-scale reactor. Because requirements will drive the design of the FHTR, a significant effort is being undertaken to define requirements and understand the tradeoffs that will be required for a practical design. The preliminary requirements include specifications for design parameters and necessary tests of major reactor systems. Testing requirements include demonstration of components, systems, and procedures for refueling, instrumentation, salt temperature control to avoid coolant freezing, salt chemistry and volume control, tritium monitoring and control, and in-service inspection. Safety tests include thermal hydraulics, neutronics - including intrinsic core shutdown mechanisms such as Doppler feedback - and decay heat removal systems. Materials and coolant testing includes fuels (including mechanical wear and fatigue) and system corrosion behavior. Preliminary analysis indicates a thermal power output below 30 MW, an initial core using pebble-bed or prismatic-block fuel, peak outlet temperatures of at least 700 deg. C, and use of FLi{sup 7}Be ({sup 7}LiF-BeF{sub 2}) coolant. The option to change-out the reactor core, fuel type, and major components is being investigated. While the FHTR will be used for materials testing, its primary mission is as a reactor system performance test to enable the design and licensing of a FHR demonstration power reactor. (authors)

  18. Core Design Characteristics of the Fluoride Salt-Cooled High Temperature Demonstration Reactor

    SciTech Connect

    Brown, Nicholas R; Qualls, A L; Betzler, Benjamin R; Carbajo, Juan J; Greenwood, Michael Scott; Hale, Richard Edward; Harrison, Thomas J; Powers, Jeffrey J; Robb, Kevin R

    2016-01-01

    Fluoride salt-cooled high temperature reactors (FHRs) are a promising reactor technology option with significant knowledge gaps to implementation. One potential approach to address those technology gaps is via a small-scale demonstration reactor with the goal of increasing the technology readiness level (TRL) of the overall system for the longer term. The objective of this paper is to outline a notional concept for such a system, and to address how the proposed concept would advance the TRL of FHR concepts. Development of the proposed FHR Demonstration Reactor (DR) will enable commercial FHR deployment through disruptive and rapid technology development and demonstration. The FHR DR will close remaining gaps to commercial viability. Lower risk technologies are included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated within an acceptable budget and schedule. Important capabilities that will be demonstrated by building and operating the FHR DR include core design methodologies; fabrication and operation of high temperature reactors; salt procurement, handling, maintenance, and ultimate disposal; salt chemistry control to maximize vessel life; tritium management; heat exchanger performance; pump performance; and reactivity control. The FHR DR is considered part of a broader set of FHR technology development and demonstration efforts, some of which are already underway. Nonreactor test efforts (e.g., heated salt loops or loops using simulant fluids) can demonstrate many technologies necessary for commercial deployment of FHRs. The FHR DR, however, fulfills a crucial role in FHR technology development by advancing the technical maturity and readiness level of the system as a whole.

  19. An Analysis of Testing Requirements for Fluoride Salt Cooled High Temperature Reactor Components

    SciTech Connect

    Holcomb, David Eugene; Cetiner, Sacit M; Flanagan, George F; Peretz, Fred J; Yoder Jr, Graydon L

    2009-11-01

    This report provides guidance on the component testing necessary during the next phase of fluoride salt-cooled high temperature reactor (FHR) development. In particular, the report identifies and describes the reactor component performance and reliability requirements, provides an overview of what information is necessary to provide assurance that components will adequately achieve the requirements, and then provides guidance on how the required performance information can efficiently be obtained. The report includes a system description of a representative test scale FHR reactor. The reactor parameters presented in this report should only be considered as placeholder values until an FHR test scale reactor design is completed. The report focus is bounded at the interface between and the reactor primary coolant salt and the fuel and the gas supply and return to the Brayton cycle power conversion system. The analysis is limited to component level testing and does not address system level testing issues. Further, the report is oriented as a bottom-up testing requirements analysis as opposed to a having a top-down facility description focus.

  20. Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors

    SciTech Connect

    Yoder Jr, Graydon L; Elkassabgi, Yousri M.; De Leon, Gerardo I.; Fetterly, Caitlin N.; Ramos, Jorge A.; Cunningham, Richard Burns

    2012-02-01

    Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental

  1. Identification and evaluation of alternatives for the disposition of fluoride fuel and flush salts from the molten salt reactor experiment at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-08-15

    This document presents an initial identification and evaluation of the alternatives for disposition of the fluoride fuel and flush salts stored in the drain tanks at the Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory (ORNL). It will serve as a resource for the U.S. Department of Energy contractor preparing the feasibility study for this activity under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). This document will also facilitate further discussion on the range of credible alternatives, and the relative merits of alternatives, throughout the time that a final alternative is selected under the CERCLA process.

  2. [Dental fluorosis prevalence in eight cohorts of Mexicans born during the implementation of the Fluoridated Domestic Salt National Program].

    PubMed

    Casanova-Rosado, Alejandro José; Medina-Solís, Carlo Eduardo; Casanova-Rosado, Juan Fernando; Vallejos-Sánchez, Ana Alicia; de la Rosa-Santillana, Rubén; Mendoza-Rodríguez, Martha; Villalobos-Rodelo, Juan José; Maupomé, Gerardo

    2013-01-01

    to determine the effect of birth cohort on dental fluorosis in Mexican schoolchildren during the implementation of the national program to fluoridate domestic salt. in a cross-sectional study we examined 1,644 schoolchildren 6-13 years old born between 1985-1992 in Campeche, México; a community where there is negligible naturally available fluoride in water supplies. Dental fluorosis was assessed with the Dean’s index in the permanent dentition. Questionnaires were used to identify diverse socio-demographic and socio-economic variables. In the statistical analysis logistic regression was used. the prevalence of fluorosis was 15.5%. In the multivariate model,we observed fluorosis was associated with larger family sizes (OR: 0.91; 95% CI: 0.84-0.99) and female sex (OR: 0.74; 95%CI: 0.57-0.98). Furthermore, using the cohort of 1985 as a comparison group, no significant dental fluorosis differences were found with those born between 1986-1987; in contrast, in the cohorts born between 1989-1992 the risk of dental fluorosis increased by almost four times (p < 0.05). the prevalence of fluorosis was low compared to other studies in Mexico. In this community with negligible fluoride in water supplies the likelihood of dental fluorosis increased as the windows of susceptibility in birth cohorts were closer to the chronologic beginning of the national domestic salt fluoridation program in 1991. This trend was more apparent after 1991.

  3. Preparation of Ti3C2 and Ti2C MXenes by fluoride salts etching and methane adsorptive properties

    NASA Astrophysics Data System (ADS)

    Liu, Fanfan; Zhou, Aiguo; Chen, Jinfeng; Jia, Jin; Zhou, Weijia; Wang, Libo; Hu, Qianku

    2017-09-01

    Here we reported the preparation of Ti3C2 MXene and Ti2C MXene by etching Ti3AlC2 and Ti2AlC with various fluoride salts in hydrochloric acid (HCl), including lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), and ammonium fluoride (NH4F). As-prepared Ti2C was further delaminated by urea, dimethylsulfoxide or ammonium hydroxide. Based on theoretical calculation and XPS results, the type of positive ions (Li+, Na+, K+, or NH4+) in etchant solution affect the surface structure of prepared MXene, which, in turn, affects the methane adsorption properties of MXene. The highest methane adsorption capacity is 8.5 cm3/g for Ti3C2 and 11.6 cm3/g for Ti2C. MXenes made from LiF and NH4F can absorb methane under high pressure and can keep methane under normal pressure, these MXenes may have important application on capturing methane or other hazardous gas molecules. MXenes made from NaF and KF can absorb methane under high pressure and release methane under low pressure. They can have important application in the adsorb storage of nature gas.

  4. 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.

  5. Study on the electrochemical extraction of rare earth elements from FLINAK

    SciTech Connect

    Long, Dewu; Huang, Wei; Jiang, Feng; Tian, Lifang; Li, Qingnuan

    2013-07-01

    Electrochemical behaviors of rare earth elements, such as NdF{sub 3}, GdF{sub 3}, SmF{sub 3}, YF{sub 3}, and EuF{sub 3}, were investigated in a LiF-NaF-KF (46.5-11.5-42.0 mol %, FLINAK, m. p. 454 Celsius degrees) solvent. The results indicated that it is possible to extract Nd, Gd and Y directly by electrochemical deposition since the reductions of those cations to metal are located in the electrochemical window of the FLINAK eutectic, while the reductions of Sm and Eu metal are out of the range of the medium. Subsequently electro-deposition of Nd was carried out with two kinds of cathodic materials, namely, an inert cathode, Pt, and a reactive electrode, Cu. The collected products were characterized by various techniques revealing that a Nd-rich product was obtained. (authors)

  6. Nuclear data libraries assessment for modelling a small fluoride salt-cooled, high-temperature reactor

    NASA Astrophysics Data System (ADS)

    Mohamed, Hassan; Lindley, Benjamin; Parks, Geoffrey

    2017-01-01

    Nuclear data consists of measured or evaluated probabilities of various fundamental physical interactions involving the nuclei of atoms and their properties. Most fluoride salt-cooled high-temperature reactor (FHR) studies that were reviewed do not give detailed information on the data libraries used in their assessments. Therefore, the main objective of this data libraries comparison study is to investigate whether there are any significant discrepancies between main data libraries, namely ENDF/B-VII, JEFF-3.1 and JEF-2.2. Knowing the discrepancies, especially its magnitude, is important and relevant for readers as to whether further cautions are necessary for any future verification or validation processes when modelling an FHR. The study is performed using AMEC's reactor physics software tool, WIMS. The WIMS calculation is simply a 2-D infinite lattice of fuel assembly calculation. The comparison between the data libraries in terms of infinite multiplication factor, kinf and pin power map are presented. Results show that the discrepancy between JEFF-3.1 and ENDF/B-VII libraries is reasonably small but increases as the fuel depletes due to the data libraries uncertainties that are accumulated at each burnup step. Additionally, there are large discrepancies between JEF-2.2 and ENDF/B-VII because of the inadequacy of the JEF-2.2 library.

  7. Preliminary Demonstration Reactor Point Design for the Fluoride Salt-Cooled High-Temperature Reactor

    SciTech Connect

    Qualls, A. L.; Betzler, Benjamin R.; Brown, Nicholas R.; Carbajo, Juan; Greenwood, Michael Scott; Hale, Richard Edward; Harrison, Thomas J.; Powers, Jeffrey J.; Robb, Kevin R.; Terrell, Jerry W.

    2015-12-01

    Development of the Fluoride Salt-Cooled High-Temperature Reactor (FHR) Demonstration Reactor (DR) is a necessary intermediate step to enable commercial FHR deployment through disruptive and rapid technology development and demonstration. The FHR DR will utilize known, mature technology to close remaining gaps to commercial viability. Lower risk technologies are included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated within an acceptable budget and schedule. These technologies include tristructural-isotropic (TRISO) particle fuel, replaceable core structural material, the use of that same material for the primary and intermediate loops, and tube-and-shell heat exchangers. This report provides an update on the development of the FHR DR. At this writing, the core neutronics and thermal hydraulics have been developed and analyzed. The mechanical design details are still under development and are described to their current level of fidelity. It is anticipated that the FHR DR can be operational within 10 years because of the use of low-risk, near-term technology options.

  8. Fluoride Salt-Cooled High-Temperature Demonstration Reactor Point Design

    SciTech Connect

    Qualls, A. L.; Brown, Nicholas R.; Betzler, Benjamin R.; Carbajo, Juan; Hale, Richard Edward; Harrison, Thomas J.; Powers, Jeffrey J.; Robb, Kevin R.; Terrell, Jerry W.; Wysocki, Aaron J.

    2016-02-01

    The fluoride salt-cooled high-temperature reactor (FHR) demonstration reactor (DR) is a concept for a salt-cooled reactor with 100 megawatts of thermal output (MWt). It would use tristructural-isotropic (TRISO) particle fuel within prismatic graphite blocks. FLiBe (2 LiF-BeF2) is the reference primary coolant. The FHR DR is designed to be small, simple, and affordable. Development of the FHR DR is a necessary intermediate step to enable near-term commercial FHRs. Lower risk technologies are purposely included in the initial FHR DR design to ensure that the reactor can be built, licensed, and operated within an acceptable budget and schedule. These technologies include TRISO particle fuel, replaceable core structural material, the use of that same material for the primary and intermediate loops, and tube-and-shell primary-to-intermediate heat exchangers. Several preconceptual and conceptual design efforts that have been conducted on FHR concepts bear a significant influence on the FHR DR design. Specific designs include the Oak Ridge National Laboratory (ORNL) advanced high-temperature reactor (AHTR) with 3400/1500 MWt/megawatts of electric output (MWe), as well as a 125 MWt small modular AHTR (SmAHTR) from ORNL. Other important examples are the Mk1 pebble bed FHR (PB-FHR) concept from the University of California, Berkeley (UCB), and an FHR test reactor design developed at the Massachusetts Institute of Technology (MIT). The MIT FHR test reactor is based on a prismatic fuel platform and is directly relevant to the present FHR DR design effort. These FHR concepts are based on reasonable assumptions for credible commercial prototypes. The FHR DR concept also directly benefits from the operating experience of the Molten Salt Reactor Experiment (MSRE), as well as the detailed design efforts for a large molten salt reactor concept and its breeder variant, the Molten Salt Breeder Reactor. The FHR DR technology is most representative of the 3400 MWt AHTR

  9. Modification of polymorphisms in polyvinylidene fluoride thin films via water and hydrated salt.

    PubMed

    Song, Rui; Xia, Guangmei; Xing, Xueqing; He, Linghao; Zhao, Qiaoling; Ma, Zhi

    2013-07-01

    In this study, the effects of solvent and magnesium chloride hexahydrate (MgCl2·6H2O) on the polymorphism of polyvinylidene fluoride (PVDF) thin films were systematically investigated. Wherein, N,N-dimethylformamide (DMF) and water with different volume ratio were used as mixed solvents to obtain the solution casting films, P series. In addition, MgCl2·6H2O was comparatively added to prepare PVDF/MgCl2·6H2O hybrid films, P-M series. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimeter (DSC) were utilized to study the influence of the water content in the mixed solvents and the hydrated salt on crystallization behavior of PVDF. Further, the morphologic images from scanning electronic microscopy (SEM) and polarized optical microscopy (POM), as well as the pizoelectirc d33 test also supplies the corresponding evidences. As indicated, the water in the mixed solvent shows different effect on main crystal forms of PVDF. At low water content, the solvents may favor the polar phase (β- and γ-phase) mainly by hydrogen bonds interactions between PVDF and water, together with dipolar interactions between PVDF and DMF. At high water content, the nonsolvent water will impose confinement effect on polymer chain diffusion and crystal growth which facilitate the formation of α-phase PVDF. Moreover, magnesium chloride hexahydrate mainly functioned as the nucleation sites for PVDF crystallization. The result of small-angle X-ray scattering (SAXS) implies the content of water or MgCl2·6H2O has little impact on the structure of the long period.

  10. Carbide Coatings for Nickel Alloys, Graphite and Carbon/Carbon Composites to be used in Fluoride Salt Valves

    SciTech Connect

    Nagle, Denis; Zhang, Dajie

    2015-10-22

    The focus of this research was concerned with developing materials technology that supports the evolution of Generation IV Advanced High Temperature Reactor (AHTR) concepts. Specifically, we investigate refractory carbide coatings for 1) nickel alloys, and 2) commercial carbon-carbon composites (CCCs). Numerous compelling reasons have driven us to focus on carbon and carbide materials. First, unlike metals, the strength and modulus of CCCs increase with rising temperature. Secondly, graphite and carbon composites have been proven effective for resisting highly corrosive fluoride melts such as molten cryolite [Na₃AlF₆] at ~1000°C in aluminum reduction cells. Thirdly, graphite and carbide materials exhibit extraordinary radiation damage tolerance and stability up to 2000°C. Finally, carbides are thermodynamically more stable in liquid fluoride salt than the corresponding metals (i.e. Cr and Zr) found in nickel based alloys.

  11. Liquid Salts as Media for Process Heat Transfer from VHTR's: Forced Convective Channel Flow Thermal Hydraulics, Materials, and Coating

    SciTech Connect

    Sridharan, Kumar; Anderson, Mark; Allen, Todd; Corradini, Michael

    2012-01-30

    The goal of this NERI project was to perform research on high temperature fluoride and chloride molten salts towards the long-term goal of using these salts for transferring process heat from high temperature nuclear reactor to operation of hydrogen production and chemical plants. Specifically, the research focuses on corrosion of materials in molten salts, which continues to be one of the most significant challenges in molten salts systems. Based on the earlier work performed at ORNL on salt properties for heat transfer applications, a eutectic fluoride salt FLiNaK (46.5% LiF-11.5%NaF-42.0%KF, mol.%) and a eutectic chloride salt (32%MgCl2-68%KCl, mole %) were selected for this study. Several high temperature candidate Fe-Ni-Cr and Ni-Cr alloys: Hastelloy-N, Hastelloy-X, Haynes-230, Inconel-617, and Incoloy-800H, were exposed to molten FLiNaK with the goal of understanding corrosion mechanisms and ranking these alloys for their suitability for molten fluoride salt heat exchanger and thermal storage applications. The tests were performed at 850C for 500 h in sealed graphite crucibles under an argon cover gas. Corrosion was noted to occur predominantly from dealloying of Cr from the alloys, an effect that was particularly pronounced at the grain boundaries Alloy weight-loss 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 was also found to correlate to the concentration of carbon present for the nominally 20% Cr containing alloys, due to the formation of chromium carbide phases at the grain boundaries. Experiments involving molten salt exposures of Incoloy-800H in Incoloy-800H crucibles under an argon cover gas showed a significantly lower corrosion for this alloy than when tested in a graphite crucible. Graphite significantly accelerated alloy corrosion due to the reduction of Cr from solution by graphite and formation

  12. Purification and Chemical Control of Molten Li2BeF 4 for a Fluoride Salt Cooled Reactor

    NASA Astrophysics Data System (ADS)

    Kelleher, Brian Christopher

    Out of the many proposed generation IV, high-temperature reactors, the molten salt reactor (MSR) is one of the most promising. The first large scale MSR, the molten salt reactor experiment (MSRE), operated from 1965 to 1969 using Li2BeF4, or flibe, as a coolant and solvent for uranium fluoride fuel, at maximum temperatures of 654°C, for over 15000 hours. The MSRE experienced no concept breaking surprises and was considered a success. Newly proposed designs of molten salt reactors use solid fuels, making them less exotic compared to the MSRE. However, any molten salt reactor will require a great deal of research pertaining to the chemical and mechanical mastery of molten salts in order to prepare it for commercialization. To supplement the development of new molten salt reactors, approximately 100 kg of flibe was purified using the standard hydrofluorination process. Roughly half of the purified salt was lithium-7 enriched salt from the secondary loop of the MSRE. Purification rids the salt of impurities and reduces its capacity for corrosion, also known as the redox potential. The redox potential of flibe was measured at various stages of purification for the first time using a dynamic beryllium reference electrode. These redox measurements have been superimposed with metal impurities measurements found by neutron activation analysis. Lastly, reductions of flibe with beryllium metal have been investigated. Over reductions have been performed, which have shown to decrease redox potential while seemingly creating a beryllium-beryllium halide system. Recommendations of the lowest advisable redox potential for corrosion tests are included along with suggestions for future work.

  13. Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 to 1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.; Whittenberger, J. Daniel

    1987-01-01

    Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

  14. Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 - 1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.; Whittenberger, J. Daniel

    1987-01-01

    Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

  15. Pre-Conceptual Design of a Fluoride-Salt-Cooled Small Modular Advanced High Temperature Reactor (SmAHTR)

    SciTech Connect

    Greene, Sherrell R; Gehin, Jess C; Holcomb, David Eugene; Carbajo, Juan J; Ilas, Dan; Cisneros, Anselmo T; Varma, Venugopal Koikal; Corwin, William R; Wilson, Dane F; Yoder Jr, Graydon L; Qualls, A L; Peretz, Fred J; Flanagan, George F; Clayton, Dwight A; Bradley, Eric Craig; Bell, Gary L; Hunn, John D; Pappano, Peter J; Cetiner, Sacit M

    2011-02-01

    This document presents the results of a study conducted at Oak Ridge National Laboratory during 2010 to explore the feasibility of small modular fluoride salt-cooled high temperature reactors (FHRs). A preliminary reactor system concept, SmATHR (for Small modular Advanced High Temperature Reactor) is described, along with an integrated high-temperature thermal energy storage or salt vault system. The SmAHTR is a 125 MWt, integral primary, liquid salt cooled, coated particle-graphite fueled, low-pressure system operating at 700 C. The system employs passive decay heat removal and two-out-of-three , 50% capacity, subsystem redundancy for critical functions. The reactor vessel is sufficiently small to be transportable on standard commercial tractor-trailer transport vehicles. Initial transient analyses indicated the transition from normal reactor operations to passive decay heat removal is accomplished in a manner that preserves robust safety margins at all times during the transient. Numerous trade studies and trade-space considerations are discussed, along with the resultant initial system concept. The current concept is not optimized. Work remains to more completely define the overall system with particular emphasis on refining the final fuel/core configuration, salt vault configuration, and integrated system dynamics and safety behavior.

  16. Compact non-rock-salt structures in sodium fluoride cluster ions at specific sizes revealed by ion mobility mass spectrometry.

    PubMed

    Ohshimo, Keijiro; Takahashi, Tohru; Moriyama, Ryoichi; Misaizu, Fuminori

    2014-10-30

    Structures of small sodium fluoride cluster cations, Na(n)F(n-1)(+), have been determined for n = 5-23 by ion mobility mass spectrometry. In the mass spectrum of Na(n)F(n-1)(+) cluster ions measured after collisions in the ion-drift cell, cuboid ions with near-regular hexahedron such as n = 14 (3 × 3 × 3), 23 (3 × 3 × 5), 38 (3 × 5 × 5), 63 (5 × 5 × 5), and 88 (5 × 5 × 7) were predominantly observed as magic numbers. By comparison of the collision cross sections obtained from the ion mobility measurements with theoretical ones, we have experimentally shown that the ions of n = 7 and 10 have stable non-rock-salt type structures in which one sodium atom is encapsulated into the sodium fluoride cuboid lattice. The collision cross sections of n = 12 and 13 are almost equal to that of the n = 14 cuboid. A similar feature was also observed in collision cross sections of n = 21 and 22, which are equal to that of the n = 23 cuboid. These features indicate that the cluster ions of n = 12, 13, 21, and 22 have near-cuboid structures with some surface defects.

  17. Geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples, and its possible relationship with the prevalence of enamel fluorosis in children in four municipalities of the department of Huila (Colombia).

    PubMed

    Martignon, Stefania; Opazo-Gutiérrez, Mario Omar; Velásquez-Riaño, Möritz; Orjuela-Osorio, Iván Rodrigo; Avila, Viviana; Martinez-Mier, Esperanza Angeles; González-Carrera, María Clara; Ruiz-Carrizosa, Jaime Alberto; Silva-Hermida, Blanca Cecilia

    2017-06-01

    Fluoride is an element that affects teeth and bone formation in animals and humans. Though the use of systemic fluoride is an evidence-based caries preventive measure, excessive ingestion can impair tooth development, mainly the mineralization of tooth enamel, leading to a condition known as enamel fluorosis. In this study, we investigated the geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples in four endemic enamel fluorosis sentinel municipalities of the department of Huila, Colombia (Pitalito, Altamira, El Agrado and Rivera), and its possible relationship with the prevalence of enamel fluorosis in children. The concentration of fluoride in drinking water, table salt, active sediment, rock, and soil was evaluated by means of an ion selective electrode and the geochemical analyses were performed using X-ray fluorescence. Geochemical analysis revealed fluoride concentrations under 15 mg/kg in active sediment, rock and soil samples, not indicative of a significant delivery to the watersheds studied. The concentration of fluoride in table salt was found to be under the inferior limit (less than 180 μg/g) established by the Colombian regulations. Likewise, exposure doses for fluoride water intake did not exceed the recommended total dose for all ages from 6 months. Although the evidence does not point out at rocks, soils, fluoride-bearing minerals, fluoridated salt and water, the hypothesis of these elements as responsible of the current prevalence of enamel fluorosis cannot be discarded since, aqueducts might have undergone significant changes overtime.

  18. The effects of salt concentration and foulant surface charge on hydrocarbon fouling of a poly(vinylidene fluoride) microfiltration membrane.

    PubMed

    He, Zhengwang; Kasemset, Sirirat; Kirschner, Alon Y; Cheng, Yu-Heng; Paul, Donald R; Freeman, Benny D

    2017-06-15

    The effects of inorganic salts and organic hydrocarbons on membrane fouling are often investigated independently. However, in many cases, these foulants are commonly found together, and such mixtures are rarely the subject of fouling studies. In this study, crude oil-in-water emulsions were formulated at three different added NaCl concentrations, 0, 10(-3) and 10(-1) M. Surface properties, such as surface tension and surface charge, of these emulsions and a poly(vinylidene fluoride) (PVDF) microfiltration (MF) membrane were characterized. The Derjaguin-Landau-Verwey-Overbeek (DLVO) model was utilized to simulate membrane-oil droplet and oil layer-oil droplet surface interactions. The DLVO model qualitatively predicted increasing fouling propensity with increasing emulsion salt concentration. The PVDF MF membrane was challenged with crude oil-in-water emulsions in constant permeate flux crossflow fouling tests to characterize the fouling propensity of the various emulsions, and the results were consistent with the model predictions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Fluoride salts as phase change materials for thermal energy storage in the temperature range 1000-1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1988-01-01

    Eutectic compositions and congruently melting intermediate compounds in binary and ternary fluoride salt systems were characterized for potential use as latent heat of fusion phase change materials to store thermal energy in the temperature range 1000-1400 K. The melting points and eutectic compositions for many systems with published phase diagrams were experimentally verified and new eutectic compositions having melting points between 1000 and 1400 K were identified. Heats of fusion of several binary and ternary eutectics and congruently melting compounds were experimentally measured by differential scanning calorimetry. For a few systems in which heats of mixing in the melts have been measured, heats of fusion of the eutectics were calculated from thermodynamic considerations and good agreement was obtained between the measured and calculated values. Several combinations of salts with high heats of fusion per unit mass (greater than 0.7 kJ/g) have been identified for possible use as phase change materials in advanced solar dynamic space power applications.

  20. Fluoride salts as phase change materials for thermal energy storage in the temperature range 1000-1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1988-01-01

    Eutectic compositions and congruently melting intermediate compounds in binary and ternary fluoride salt systems were characterized for potential use as latent heat of fusion phase change materials to store thermal energy in the temperature range 1000-1400 K. The melting points and eutectic compositions for many systems with published phase diagrams were experimentally verified and new eutectic compositions having melting points between 1000 and 1400 K were identified. Heats of fusion of several binary and ternary eutectics and congruently melting compounds were experimentally measured by differential scanning calorimetry. For a few systems in which heats of mixing in the melts have been measured, heats of fusion of the eutectics were calculated from thermodynamic considerations and good agreement was obtained between the measured and calculated values. Several combinations of salts with high heats of fusion per unit mass (greater than 0.7 kJ/g) have been identified for possible use as phase change materials in advanced solar dynamic space power applications.

  1. Enrichment of fluoride in groundwater under the impact of saline water intrusion at the salt lake area of Yuncheng basin, northern China

    NASA Astrophysics Data System (ADS)

    Gao, Xubo; Wang, Yanxin; Li, Yilian; Guo, Qinghai

    2007-12-01

    Long-term intake of high-fluoride groundwater causes endemic fluorosis. This study, for the first time, discovered that the salt lake water intrusion into neighboring shallow aquifers might result in elevation of fluoride content of the groundwater. Two cross-sections along the groundwater flow paths were selected to study the geochemical processes controlling fluoride concentration in Yuncheng basin, northern China. There are two major reasons for the observed elevation of fluoride content: one is the direct contribution of the saline water; the other is the undersaturation of the groundwater with respect to fluorite due to salt water intrusion, which appears to be more important reason. The processes of the fluorine activity reduction and the change of Na/Ca ratio in groundwater induced by the intrusion of saline water favor further dissolution of fluorine-bearing mineral, and it was modeled using PHREEQC. With the increase in Na concentration (by adding NaCl or Na2SO4 as Na source, calcium content kept invariable), the increase of NaF concentration was rapid at first and then became slower; and the concentrations of HF, HF{2/-}, CaF+, and MgF+ were continuously decreasing. The geochemical conditions in the study area are advantageous to the complexation of F- with Na+ and the decline of saturation index of CaF2, regardless of the water type (Cl-Na or SO4-Na type water).

  2. Improving Dental Health of DOD Related Persons Assigned to Okinawa by Using Fluoridated Salt in Lieu of Water Fluoridation: A Comparative Analysis

    DTIC Science & Technology

    1999-04-01

    these stains and discolored (mottled) teeth were due to excess fluoride consumption. This condition, now known as fluorosis , was linked to consumption of...common inference is that optimal fluoride doses represent a trade off between dental fluorosis and dental caries. There is not universal agreement...intakes prior to two years of age escalates the risk of fluorosis and that doses as low as 0.03 to 0.04 mg Fl/kg bw may be connected to fluorosis in

  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. Anti-inflammatory effects of bamboo salt and sodium fluoride in human gingival fibroblasts--An in vitro study.

    PubMed

    Lee, Hye-Jin; Choi, Choong-Ho

    2015-06-01

    Dental caries preventive agents, such as sodium fluoride (NaF) and bamboo salt (BS), are known to cause cellular growth that is characterized by morphological and gene expression changes. This study was designed to investigate the dual effect of NaF and BS on interleukin (IL)-1β-induced gingival inflammation. Under in vitro experimental conditions, exposure to a subcytotoxic dose of IL-1β enhanced human gingival fibroblast inflammation, as characterized by increased levels of inflammation-associated proteins. A combination of NaF and BS significantly protected fibroblasts from IL-1β-induced cellular deterioration. Exposure to NaF and BS induced the cell growth and no changes in viability were found with the Lactate Dehydrogenase Assay (LDH) assay at the NaF and BS concentration analyzed. Molecular analysis demonstrated that NaF and BS increased resistance to inflammation by reduction of IL-1β, IL-8, and tumor necrosis factor (TNF)-α production. In addition, NaF and BS decreased the expression of IL-1β, IL-8, and TNF-α mRNA in IL-1β-induced human gingival fibroblast cells. The study identifies a new role for NaF and BS in the IL-1β-induced inflammation of gingival fibroblasts and provides a potential target for gingival protection.

  5. Corrosion of Ferritic Steels in High Temperature Molten Salt Coolants for Nuclear Applications

    SciTech Connect

    Farmer, J; El-Dasher, B; de Caro, M S; Ferreira, J

    2008-11-25

    Corrosion of ferritic steels in high temperature molten fluoride salts may limit the life of advanced reactors, including some hybrid systems that are now under consideration. In some cases, the steel may be protected through galvanic coupling with other less noble materials with special neutronic properties such a beryllium. This paper reports the development of a model for predicting corrosion rates for various ferritic steels, with and without oxide dispersion strengthening, in FLiBe (Li{sub 2}BeF{sub 4}) and FLiNaK (Li-Na-K-F) coolants at temperatures up to 800 C. Mixed potential theory is used to account for the protection of steel by beryllium, Tafel kinetics are used to predict rates of dissolution as a function of temperature and potential, and the thinning of the mass-transfer boundary layer with increasing Reynolds number is accounted for with dimensionless correlations. The model also accounts for the deceleration of corrosion as the coolants become saturated with dissolved chromium and iron. This paper also reports electrochemical impedance spectroscopy of steels at their corrosion potentials in high-temperature molten salt environments, with the complex impedance spectra interpreted in terms of the interfacial charge transfer resistance and capacitance, as well as the electrolyte conductivity. Such in situ measurement techniques provide valuable insight into the degradation of materials under realistic conditions.

  6. Fluoride-Salt-Cooled High-Temperature Reactor (FHR) for Power and Process Heat

    SciTech Connect

    Forsberg, Charles; Hu, Lin-wen; Peterson, Per; Sridharan, Kumar

    2015-01-21

    In 2011 the U.S. Department of Energy through its Nuclear Energy University Program (NEUP) awarded a 3- year integrated research project (IRP) to the Massachusetts Institute of Technology (MIT) and its partners at the University of California at Berkeley (UCB) and the University of Wisconsin at Madison (UW). The IRP included Westinghouse Electric Company and an advisory panel chaired by Regis Matzie that provided advice as the project progressed. The first sentence of the proposal stated the goals: The objective of this Integrated Research Project (IRP) is to develop a path forward to a commercially viable salt-cooled solid-fuel high-temperature reactor with superior economic, safety, waste, nonproliferation, and physical security characteristics compared to light-water reactors. This report summarizes major results of this research.

  7. Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

    NASA Astrophysics Data System (ADS)

    Deng, Bo; Yu, Yang; Zhang, Bowu; Yang, Xuanxuan; Li, Linfan; Yu, Ming; Li, Jingye

    2011-02-01

    Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

  8. Molten Salt Heat Transport Loop: Materials Corrosion and Heat Transfer Phenomena

    SciTech Connect

    Dr. Kumar Sridharan; Dr. Mark Anderson; Dr. Michael Corradini; Dr. Todd Allen; Luke Olson; James Ambrosek; Daniel Ludwig

    2008-07-09

    An experimental system for corrosion testing of candidate materials in molten FLiNaK salt at 850 degree C has been designed and constructed. While molten FLiNaK salt was the focus of this study, the system can be utilized for evaluation of materials in other molten salts that may be of interest in the future. Using this system, the corrosion performance of a number of code-certified alloys of interest to NGNP as well as the efficacy of Ni-electroplating have been investigated. The mechanisums underlying corrosion processes have been elucidated using scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy of the materials after the corrosion tests, as well as by the post-corrosion analysis of the salts using inductively coupled plasma (ICP) and neutron activation analysis (NAA) techniques.

  9. An experimental test plan for the characterization of molten salt thermochemical properties in heat transport systems

    SciTech Connect

    Pattrick Calderoni

    2010-09-01

    Molten salts are considered within the Very High Temperature Reactor program as heat transfer media because of their intrinsically favorable thermo-physical properties at temperatures starting from 300 C and extending up to 1200 C. In this context two main applications of molten salt are considered, both involving fluoride-based materials: as primary coolants for a heterogeneous fuel reactor core and as secondary heat transport medium to a helium power cycle for electricity generation or other processing plants, such as hydrogen production. The reference design concept here considered is the Advanced High Temperature Reactor (AHTR), which is a large passively safe reactor that uses solid graphite-matrix coated-particle fuel (similar to that used in gas-cooled reactors) and a molten salt primary and secondary coolant with peak temperatures between 700 and 1000 C, depending upon the application. However, the considerations included in this report apply to any high temperature system employing fluoride salts as heat transfer fluid, including intermediate heat exchangers for gas-cooled reactor concepts and homogenous molten salt concepts, and extending also to fast reactors, accelerator-driven systems and fusion energy systems. The purpose of this report is to identify the technical issues related to the thermo-physical and thermo-chemical properties of the molten salts that would require experimental characterization in order to proceed with a credible design of heat transfer systems and their subsequent safety evaluation and licensing. In particular, the report outlines an experimental R&D test plan that would have to be incorporated as part of the design and operation of an engineering scaled facility aimed at validating molten salt heat transfer components, such as Intermediate Heat Exchangers. This report builds on a previous review of thermo-physical properties and thermo-chemical characteristics of candidate molten salt coolants that was generated as part of the

  10. 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 ...

  11. 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.

  12. Optimal Fluoridation

    PubMed Central

    Lee, John R.

    1975-01-01

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

  13. Changes in dental caries prevalence in 12-year-old students in the State of Mexico after 9 years of salt fluoridation.

    PubMed

    Irigoyen, M E; Sánchez-Hinojosa, G

    2000-01-01

    The purpose of this study was to describe the dental caries experience in 12-year-old students in the State of Mexico and to detect changes after 9 years of salt fluoridation (1988-1997). The 1987 WHO dental caries criteria were used in both surveys. The population studied encompassed 2,275 12-year-old students in 1988, and 1,138 in 1997. The proportion of 'caries-free' children was 10. 3% in the first survey and 27.7% in the second one. The mean DMFT index was 4.39 (SD 2.9) in 1988 and 2.47 (SD 2.4) in 1997, the confidence interval of the differences between DMFT means was [95% CI 1.73, 2.11]; the caries reduction detected was 43.7%. The Unmet Restorative Index was 82.3% in 1988 and 72.8% in 1997. The results of the present study indicate that the oral health status of State of Mexico students has improved during the last decade; however, there is still a need for further caries reduction and an increment in access to dental treatment.

  14. Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

    NASA Astrophysics Data System (ADS)

    Cisneros, Anselmo Tomas, Jr.

    The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP

  15. Introduction of an interproximal mineralisation model to measure remineralisation caused by novel formulations containing calcium silicate, sodium phosphate salts and fluoride.

    PubMed

    Jones, Siân Bodfel; Davies, Maria; Chapman, Nicholas; Willson, Richard; Hornby, Kate; Joiner, Andrew; West, Nicola X

    2014-06-01

    To introduce a new interproximal mineralisation model and to investigate the effectiveness of novel toothpaste and dual phase gel formulations to remineralise acid softened enamel in a simulated interproximal environment. Specimens were positioned opposite each other with an approximately 100 μm space between enamel surfaces to simulate an interproximal environment. Target specimens were demineralised in 1% (w/v) citric acid, pH3.75. Specimens were daily immersed in artificial saliva (AS) for 1h, treated with formulations, re-immersed in AS for 6h, re-treated and re-immersed in AS for a further 1h. Study 1 evaluated prototype calcium silicate/phosphate fluoride toothpaste formulations. Study 2 evaluated novel calcium silicate/phosphate fluoride toothpaste and dual phase gel formulations. Both studies contained fluoridated and non-fluoridated controls. The surface microhardness of each target enamel block was measured following demineralisation and following days three, seven and fourteen for study one and after days one, three and seven for study two. This new mineralisation model was able to show increased remineralisation from calcium silicate/phosphate fluoride prototype formulations over fluoridated formulations alone, after three and seven days of treatment. Using this new model, the combined application of novel calcium silicate/phosphate fluoride toothpaste and novel calcium silicate/phosphate fluoride dual phase gel showed the greatest amount of remineralisation, which was significantly greater than sodium fluoride and non-fluoride controls. Employing a new interproximal mineralisation model successfully determined the remineralisation potential of novel calcium silicate/phosphate fluoride oral healthcare formulations. Modifying a mineralisation model to include specimens positioned in an interproximal environment allows us to better understand the remineralisation potential of oral healthcare products. It is important to minimise mineral loss at

  16. 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.

  17. SEPARATION OF PROTACTINIUM FROM MOLTEN SALT REACTOR FUEL COMPOSITIONS

    DOEpatents

    Shaffer, J.H.; Strain, J.E.; Cuneo, D.R.; Kelly, M.J.

    1963-11-12

    A method for selectively precipitating protactinium from a neutron- irradiated fused fluoride salt composition comprising at least one metal fluoride selected from the group consisting of an alkali metal fluoride and an alkaline earth metal fluoride containing dissolved thorium-232 values is presented. An inorganic metal oxide corresponding to any of the metal fluorides of the composition is also added. (AEC)

  18. Fluoride mouthrinses and fluoride varnishes.

    PubMed

    Petersson, L G

    1993-01-01

    The cariostatic efficacy of rinsing with a 0.05-0.2% neutral sodium fluoride solution has been clearly demonstrated, especially in supervised school-based programmes in moderate and high caries risk children. The cost-benefit effect, however, is questionable in populations with low caries prevalence, and fluoride rinsing programmes are gradually being replaced by more individual fluoride therapy comprising combinations of fluoride toothpastes, tablets, or varnishes. Fluoride varnishes were developed as individual alternatives to conventional topical fluoride application and are today gaining acceptance for clinical application. Two varnishes, Duraphat containing 5% wt NaF and Fluor Protector with 0.9% wt fluor silane, are available commercially. The clinical effects seem to depend mainly on application frequency, especially in high caries risk groups. The cost-benefit effect is high, but can be increased by delegating application to auxiliary personnel in conjunction with regular dental visits. Toxicologically both fluoride mouthrinses and fluoride varnishes are safe if used as directed.

  19. Removal of fluoride from fluoride contaminated industrial waste water by electrolysis.

    PubMed

    Joshi, Vijaya A; Nanoti, Madan V

    2003-01-01

    Wastewater containing fluoride are generally treated with lime or calcium salt supplemented with aluminium salts. Wastewater generated from different industries does not always behave in the same way due to the presence of interfering contaminants. A number of techniques have been developed and studied for the removal of excessive fluoride. Most of these are based on use of aluminium salt. In alum coagulation the sorption properties of product of hydrolysis of aluminium salts and capacity of fluoride for complex formation plays a very important role. These hydrolysis products of aluminium can be produced by passing direct current through aluminium electrode. The text presented in the paper deals with the various aspect of removal of fluoride by electrolysis using aluminium electrode from fluoride chemical based industrial wastewater.

  20. 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.

  1. 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.

  2. 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, ...

  3. Water fluoridation.

    PubMed

    Parnell, C; Whelton, H; O'Mullane, D

    2009-09-01

    This was to present a summary of the evidence from systematic reviews of the effectiveness and safety of water fluoridation. A search for relevant systematic reviews was conducted using the terms Fluoridation [Mesh] OR "water fluoridation" OR fluoridation OR (water AND fluoride) and was run from 01/01/2000 to 17/10/2008 in Pubmed, Embase, the Cochrane Database of Systematic Reviews and the Database of Abstracts of Reviews of Effects in the Cochrane Library. The quality of the systematic reviews was assessed using Scottish Intercollegiate Guideline Network (SIGN) methodology checklists for systematic reviews. Websites of guideline organisations were also searched for relevant evidence-based guidelines, which were appraised using the AGREE instrument. Of the 59 publications identified, 3 systematic reviews and 3 guidelines were included in this review. While the reviews themselves were of good methodological quality, the studies included in the reviews were generally of moderate to low quality. The results of the three reviews showed that water fluoridation is effective at reducing caries in children and adults. With the exception of dental fluorosis, no association between adverse effects and water fluoridation has been established. Water fluoridation reduces caries for all social classes, and there is some evidence that it may reduce the oral health gap between social classes. Water fluoridation, where technically feasible and culturally acceptable, remains a relevant and valid choice as a population measure for the prevention of dental caries.

  4. 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

  5. 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).

  6. Other Fluoride Products

    MedlinePlus

    ... What's this? Submit What's this? Submit Button Other Fluoride Products Recommend on Facebook Tweet Share Compartir On ... August 17, 2001;50(RR-14):1–42. Fluoride Products Fluoride Toothpaste Form Concentrations of fluoride in ...

  7. 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.

  8. Monitoring fluoride exposure with fingernail clippings.

    PubMed

    Whitford, Gary M

    2005-01-01

    The purpose of this review is to discuss new information regarding the relationship between the level of fluoride exposure and the corresponding fluoride concentrations in fingernail clippings. While there are several techniques available to extract fluoride from fingernails prior to analysis with the electrode, the HMDS-facilitated diffusion method is the most popular. Fluoride enters fingernails at the growth end and reaches the distal end approximately three months later. The fluoride concentration in the clipping reflects the average fluoride intake and plasma concentration during the period when the clipping was formed. Therefore, the concentration in the clipping is directly related to the average fluoride exposure that occurred during a 1-2 week period (depending on the length of the clipping) about three months ago and not to recent and possibly variable exposures that occur during the day. Published studies have demonstrated that fingernail fluoride concentrations reflect fluoride exposures from drinking water, toothpaste and the work environment and can be expected to do so for any source of intake including salt.

  9. Fluoridated Water

    MedlinePlus

    ... based on a review of more than 50 human epidemiological (population) studies produced over the past 40 years, concluded that optimal fluoridation of drinking water “does not pose a detectable cancer risk to humans” as evidenced by extensive human epidemiological data reported ...

  10. Impact of socio-demographic, socioeconomic, and water variables on dental fluorosis in adolescents growing up during the implementation of a fluoridated domestic salt program.

    PubMed

    Pontigo-Loyola, América P; Medina-Solís, Carlo E; Lara-Carrillo, Edith; Patiño-Marín, Nuria; Escoffié-Ramirez, Mauricio; Mendoza-Rodríguez, Martha; De La Rosa-Santillana, Rubén; Maupomé, Gerardo

    2014-01-01

    The objective of this study is to determine the impact of socio-demographic, socioeconomic, and other risk indicators on dental fluorosis (DF) among Mexican adolescents. A cross-sectional study was carried out in 1,538 adolescents 12 and 15 years of age in semi-rural communities located at high altitude (>2,000 m) and with high concentration of fluoride in water (1.38-3.07 ppm) in Hidalgo, Mexico. DF was determined by means of Dean's Index and all teeth were examined. Remaining variables were collected using a questionnaire. The adjusted final model was performed using ordered logistic regression. After adjusting for sex, the variables associated with DF were (p < 0.05): being 12 years old (OR = 1.10) versus 15 years old; having lived the first 6 years of life in El Llano (3.07 F ppm) (OR = 3.19) or San Marcos (1.38 F ppm) (OR = 1.63) versus Tula (1.42 F ppm); having public (OR = 1.35) or private health insurance (OR = 1.36) versus those without insurance; belonging to the lower quartiles of socioeconomic position (SEP) [1st quartile (OR = 2.48), 2nd quartile (OR = 1.81), 3rd quartile (OR = 1.49)] versus the highest quartile; having drunk tap water (OR = 1.83) or from a well or spring (OR = 2.30) versus those who drank water purchased in large containers or bottles. Demographic and socioeconomic variables were associated with DF. While better SEP appeared to play an important role in DF, a pattern of water intake associated with water purchased in large containers or bottles (which have different connotations to the use of bottled water in industrialized Western countries) did reduce DF risk in these high fluoride content, high altitude communities.

  11. 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.

  12. [Dental fluorosis prevalence in Mexican localities of 27 states and the D.F.: six years after the publication of the Salt Fluoridation Mexican Official Regulation].

    PubMed

    Betancourt-Lineares, Armandor; Irigoyen-Camacho, María Esther; Mejía-González, Adriana; Zepeda-Zapeda, Marco; Sánchez-Pérez, Leonor

    2013-01-01

    To identify the prevalence and severity of dental fluorosis in communities located in 28 states of Mexico. The National Dental Caries Survey 2001 (NDCS2001) data base was analyzed. The information of 26,893 students, ages 12 and 15 years old, of 27 states and the Federal District was examined. Dean's dental fluorosis index was applied by standardized examiners. The fluorosis prevalence and the Community Fluorosis Index (FCI) were calculated. The fluorosis prevalence was 27.9% (95% CI 24.4, 28.5). A statistical significance difference in the fluorosis prevalence was observed among the states studied (p < 0.0001). The lowest prevalence was detected in Morelos (3.2%) and the highest in Durango (88.8%). In 18 (64.3%) of the states included more than 90% of the participants showed very mild or lower levels of the dental fluorosis index. A low level of the FCI was found in the localities belonging to 19 (67.9%) of the states studied (FCI < 0.4). The lowest FCI was found in Colima, Yucatán and Morelos. The highest FCI were found in Durango, Zacatecas, Aguascalientes and San Luis Potosí (1 ≤ ICF). This information indicates that in these states dental fluorosis is a public health problem. Two-thirds of the states had localities with low prevalence of dental fluorosis; however, approximately, one-third of the states investigated the fluorosis levels showed the need of a reduction in fluoride exposure among the young population.

  13. The corrosion behavior of CVI SiC matrix in SiCf/SiC composites under molten fluoride salt environment

    NASA Astrophysics Data System (ADS)

    Wang, Hongda; Feng, Qian; Wang, Zhen; Zhou, Haijun; Kan, Yanmei; Hu, Jianbao; Dong, Shaoming

    2017-04-01

    High temperature corrosion behavior and microstructural evolution of designed chemical-vapor-infiltrated SiC matrix in SiC fiber reinforced SiC ceramic matrix composites in 46.5LiF-11.5NaF-42.0KF (mol. %) eutectic salt at 800 °C for various corrosion time was studied. Worse damage was observed as extending the exposure time, with the mass loss ratio increasing from 0.716 wt. % for 50 h to 5.914 wt. % for 500 h. The mass loss rate showed a trend of first decrease and then increase with the extended corrosion exposure. Compared with the near-stoichiometric SiC matrix layers, the O-contained boundaries between deposited matrix layers and the designed Si-rich SiC matrix layers were much less corrosion resistant and preferentially corroded. Liner relationship between the mass loss ratio and the corrosion time obtained from 50 h to 300 h indicated that the corrosion action was reaction-control process. Further corrosion would lead to matrix layer exfoliation and higher mass loss ratio.

  14. 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 ...

  15. Private Well Water and Fluoride

    MedlinePlus

    ... well. What do I need to know about fluoride and groundwater from a well? Fluoride is present ... well has less than the recommended level of fluoride for preventing tooth decay? The recommended fluoride level ...

  16. 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 ...

  17. Practitioner's guide to fluoride.

    PubMed

    Scheifele, Erik; Studen-Pavlovich, Deborah; Markovic, Nina

    2002-10-01

    The current health care trend is to provide evidence-based recommendations and treatment. Many literature reviews have shown fluoride's effectiveness against caries. The current use of fluoride in the prevention of dental caries is based on community, professional, and individual strategies. Personalized fluoride regimens should include a risk analysis and a review of the patient's current fluoride exposure. The future of fluoride may be found in its slow release and retention in the oral cavity through various modalities. Because of the many uncertainties still associated with fluoride, further research is needed.

  18. Organic Perfluorohalogenate Salts; New Energetic Materials

    DTIC Science & Technology

    2014-06-01

    Cesium Hexadecafluorotriiodide Ion In an earlier report Hargreaves reported the results of a study on the reaction of iodide salts with IF5. It is...as methathatical reactions (Reaction 4) with cesium IF6- initially produced colorless solids which upon standing at room temperature decomposed. It...of the cesium salt of a complex anion with tetramethylammonium fluoride in an appropriate solvent (Figure 18). The reaction of Cesium fluoride with

  19. 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. ...

  20. Fluoridation update 2014.

    PubMed

    Allukian, Myron; Wong, Chloe

    2014-01-01

    This year more than 4 million people living in 140 communities in Massachusetts will have the health and economic benefits of community water fluoridation. However Massachusetts is ranked only 37th in the country for fluoridation, with just 62 percent of the population on a public water supply living in fluoridated communities. Nationally, more than 210 million Americans, about 74.6 percent of the U.S. population on a community water supply live in fluoridated communities.

  1. Reviews of the environmental effects of pollutants. IX. Fluoride

    SciTech Connect

    Drury, J.S.; Ensminger, J.T.; Hammons, A.S.; Holleman, J.W.; Lewis, E.B.; Preston, E.L.; Shriner, C.R.; Towill, L.E.

    1980-09-01

    This study is a comprehensive, multidisciplinary review of the health and environmental effects of fluoride on microorganisms, plants, wild and domestic animals, and humans. More than 1000 references are cited. Human intake of fluoride is chiefly through the diet; drinking water is normally the largest single source. Low concentrations of fluoride in water (approximately 1 ppM) benefit mammalian systems, making bone and tooth apatite less soluble, but long-term ingestion of water containing more than 8 ppM fluoride causes fluorosis in humans. Fluoride salts are lethal to humans when ingested in doses of about 3 g or more. At concentrations normally encountered by the general public, fluoride is not teratogenic, mutagenic, or carcinogenic to humans, but chronic fluoride toxicosis of both livestock and wildlife is an important problem in many areas of the United States. The principal manifestations of chronic fluoride toxicosis in livestock are dental fluorosis, osteofluorosis, lameness, and impaired performance. Among domestic animals, dairy cattle are the most sensitive to excessive fluoride exposure.

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

    PubMed Central

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

    2014-01-01

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

  3. Cladding Alloys for Fluoride Salt Compatibility

    SciTech Connect

    Muralidharan, Govindarajan; Wilson, Dane F; Walker, Larry R; Santella, Michael L; Holcomb, David Eugene

    2011-06-01

    This report provides an overview of several candidate technologies for cladding nickel-based corrosion protection layers onto high-temperature structural alloys. The report also provides a brief overview of the welding and weld performance issues associated with joining nickel-clad nickel-based alloys. From the available techniques, two cladding technologies were selected for initial evaluation. The first technique is a line-of-sight method that would be useful for cladding large structures such as vessel interiors or large piping. The line-of-sight method is a laser-based surface cladding technique in which a high-purity nickel powder mixed into a polymer binder is first sprayed onto the surface, baked, and then rapidly melted using a high-power laser. The second technique is a vapor phase technique based on the nickel-carbonyl process that is suitable for cladding inaccessible surfaces such as the interior surfaces of heat exchangers. An initial evaluation for performed on the quality of nickel claddings processed using the two selected cladding techniques.

  4. [Arsenic (V) removal from drinking water by ferric salt and aluminum salt coagulation/microfiltration process].

    PubMed

    Li, Xiao-bo; Wu, Shui-bo; Gu, Ping

    2007-10-01

    Two lab-scale coagulation/microfiltration membrane reactors were used to compare the arsenic removal from drinking water by ferric salt and aluminum salt coagulation/microfiltration process. FeCl3 and Al2(SO4)3 were appointed as the coagulants. The results show that the arsenic removal efficiency of the two processes are almost equal. Arsenic concentration can be lowered from about 100 microg/L to below 10 microg/L and the lowest is 1.68 microg x L(-1). All of the turbidity of the treated water is less than 0.1 NTU. The concentrations of ferric, aluminum and SO4(2-) of the treated water are entirely satisfied the standard of drinking water. After treated by ferric salt process, pH value of the treated water is increased about 0.5. However, aluminum salt process does not change pH of the drinking water. The concentration ratio of the ferric salt process is 1,791 which is about 2.54 times of the aluminum salt process. Arsenic concentration of the sludge of ferric salt process is also higher greatly than that of the aluminum salt process. Therefore, the volume of the sludge produced by the ferric salt process is smaller than that of the aluminum salt process when equal amount of drinking water was treated. Accordingly, ferric salt process should be used when only high concentration arsenic existed in drinking water. On the other hand, fluoride also can be removed simultaneously while arsenic was removed by aluminum salt process. The amount of coagulant needed is the amount of coagulant required to remove fluoride separately. Fluoride can not be removed from drinking water by the ferric salt process. It was concluded that aluminum salt process should be used to remove arsenic and fluoride simultaneously from high arsenic and high fluoride coexisted drinking water.

  5. Fluoride and chlorhexidine release from filled resins.

    PubMed

    Shen, C; Zhang, N-Z; Anusavice, K J

    2010-09-01

    Resin-based materials that release either fluoride or chlorhexidine have been formulated for inhibiting caries activity. It is not known if the two agents, when incorporated into one material, would interact and affect their release potential. We hypothesized that the ratio of fluoride to chlorhexidine incorporated into a resin, and the pH of the storage medium, will affect their releases from the material. The material investigated contained 23 wt% of filler, and the ratios of calcium fluoride to chlorhexidine diacetate were 8/2, 5/5, and 2/8. The release was conducted in pH 4, 5, and 6 acetate buffers. The results showed that release of either agent increased as the pH of the medium decreased. The presence of fluoride salt substantially reduced the chlorhexidine release, while the presence of a specific quantity of chlorhexidine significantly increased fluoride release. This interaction can be utilized to optimize the release of either agent for therapeutic purposes.

  6. Fluoride and Chlorhexidine Release from Filled Resins

    PubMed Central

    Shen, C.; Zhang, N.-Z.; Anusavice, K.J.

    2010-01-01

    Resin-based materials that release either fluoride or chlorhexidine have been formulated for inhibiting caries activity. It is not known if the two agents, when incorporated into one material, would interact and affect their release potential. We hypothesized that the ratio of fluoride to chlorhexidine incorporated into a resin, and the pH of the storage medium, will affect their releases from the material. The material investigated contained 23 wt% of filler, and the ratios of calcium fluoride to chlorhexidine diacetate were 8/2, 5/5, and 2/8. The release was conducted in pH 4, 5, and 6 acetate buffers. The results showed that release of either agent increased as the pH of the medium decreased. The presence of fluoride salt substantially reduced the chlorhexidine release, while the presence of a specific quantity of chlorhexidine significantly increased fluoride release. This interaction can be utilized to optimize the release of either agent for therapeutic purposes. PMID:20581354

  7. The water fluoridation debate.

    PubMed

    McGrady, Michael G; Ellwood, Roger P; Pretty, Iain A

    2011-01-01

    Water fluoridation schemes have been employed for over 50 years. Water fluoridation has been a source of continuous debate between those who advocate its use as a public health measure and those who oppose it. There have been no new fluoridation schemes in the U.K. for nearly 30 years owing to principally legislative, but also geographic, financial, and political reasons. However, in early 2008, the U.K. Secretary of State for Health promoted the use of water fluoridation schemes for areas in England with the highest rates of decay. This article, the third and final article of three, aims to discuss the arguments surrounding water fluoridation and its continued relevance as a public health measure. This article aims to provide an update for general practitioners for the background and the current status of the water fluoridation debate and to enable them to answer non-clinical questions raised by patients.

  8. Bath Salts

    MedlinePlus

    ... Surgery? A Week of Healthy Breakfasts Shyness Bath Salts KidsHealth > For Teens > Bath Salts Print A A ... Someone Quit? Avoiding Bath Salts What Are Bath Salts? The name "bath salts" sounds innocent, but don' ...

  9. Fluoride in dental erosion.

    PubMed

    Magalhães, Ana Carolina; Wiegand, Annette; Rios, Daniela; Buzalaf, Marília Afonso Rabelo; Lussi, Adrian

    2011-01-01

    Dental erosion develops through chronic exposure to extrinsic/intrinsic acids with a low pH. Enamel erosion is characterized by a centripetal dissolution leaving a small demineralized zone behind. In contrast, erosive demineralization in dentin is more complex as the acid-induced mineral dissolution leads to the exposure of collagenous organic matrix, which hampers ion diffusion and, thus, reduces further progression of the lesion. Topical fluoridation inducing the formation of a protective layer on dental hard tissue, which is composed of CaF(2) (in case of conventional fluorides like amine fluoride or sodium fluoride) or of metal-rich surface precipitates (in case of titanium tetrafluoride or tin-containing fluoride products), appears to be most effective on enamel. In dentin, the preventive effect of fluorides is highly dependent on the presence of the organic matrix. In situ studies have shown a higher protective potential of fluoride in enamel compared to dentin, probably as the organic matrix is affected by enzymatical and chemical degradation as well as by abrasive influences in the clinical situation. There is convincing evidence that fluoride, in general, can strengthen teeth against erosive acid damage, and high-concentration fluoride agents and/or frequent applications are considered potentially effective approaches in preventing dental erosion. The use of tin-containing fluoride products might provide the best approach for effective prevention of dental erosion. Further properly designed in situ or clinical studies are recommended in order to better understand the relative differences in performance of the various fluoride agents and formulations. Copyright © 2011 S. Karger AG, Basel.

  10. 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. Copyright © 2013 S. Karger AG, Basel.

  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. 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.

  14. Perspectives in the effective use of fluoride in Asia.

    PubMed

    Petersen, P E; Phantumvanit, P

    2012-02-01

    Dental caries is the most prevalent chronic disease affecting human populations worldwide. The diverse disease patterns across and within countries are related to socio-behavioral determinants, demographic factors, environmental conditions, and the availability and accessibility of oral health services, in particular, exposure to disease prevention programs (Petersen, 2003, 2008a). Benefits of fluoride for caries prevention have been substantiated in many countries (Petersen and Lennon, 2004; Jones et al., 2005). In the second half of the 20th century, this focus shifted to the development and evaluation of fluoride toothpastes and rinses and, to a lesser extent, to alternatives to water fluoridation, such as salt and milk fluoridation. Most recently, efforts have been made to summarize this extensive database through systematic reviews of fluoride administration (McDonagh et al., 2000; Marinho et al., 2003; Australian Government, 2007). The Asian workshop held in Phan-Nga, Thailand, during March 22-24, 2011, aimed to discuss current information on fluoride and dental caries, as well as to try identifying barriers and opportunities that countries of Asia may have for implementing such programs. In addition, the intention was to give recommendations for including fluoride schemes within national public health programs.

  15. The role of fluoride in montmorillonite-catalyzed RNA synthesis.

    PubMed

    Aldersley, Michael F; Joshi, Prakash C

    2014-05-01

    The montmorillonite-catalyzed reactions of the 5'-phosphorimidazolide of adenosine in the presence of fluoride were investigated to complete our study on the effect of salts on this type of reaction. Both anions and cations have been found to influence the oligomerization reactions of the activated nucleotides, being used here as a model system for pre-biotic RNA synthesis. However, in total contrast to the behavior of the activated nucleotides in the presence of montmorillonite and other salts, alkali metal fluorides did not yield any detectable oligomerization products except in very dilute (<0.005 M) solutions of fluoride. Instead, 5'-phosphorofluoridates were formed. Their identity was confirmed by a combination of HPLC, mass spectrometry, synthesis, and NMR.

  16. The prevalence of fluorosis in children is associated with naturally occurring water fluoride concentration in Mexico.

    PubMed

    Mariño, Rodrigo

    2013-09-01

    Fluorosis and dental caries in Mexican schoolchildren residing in areas with different water fluoride concentrations and receiving fluoridated salt. Garcia-Perez A, Irigoyen-Carnacho ME, Borges-Yanez A. Caries Res 2013;47(4):299-308. Rodrigo Mariño Is there an association between the presence of dental fluorosis and fluoride concentration in drinking water? and Is there an association between the severity of fluorosis and dental caries experience in schoolchildren residing in two rural towns in Mexico (with water fluoride concentrations of 0.70 and 1.50 ppm) that also receive fluoridated salt? Government: National Council of Science and Technology (Consejo Nacional de Ciencia y Tecnologia, CONACYT) Other: Autonomous University, Xochimilco (Universidad Autonoma Metropolitana, UAM-X) TYPE OF STUDY/DESIGN: Cross-sectional Level 3: Other evidence Not applicable. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Molten salt bath circulation design for an electrolytic cell

    DOEpatents

    Dawless, Robert K.; LaCamera, Alfred F.; Troup, R. Lee; Ray, Siba P.; Hosler, Robert B.

    1999-01-01

    An electrolytic cell for reduction of a metal oxide to a metal and oxygen has an inert anode and an upwardly angled roof covering the inert mode. The angled roof diverts oxygen bubbles into an upcomer channel, thereby agitating a molten salt bath in the upcomer channel and improving dissolution of a metal oxide in the molten salt bath. The molten salt bath has a lower velocity adjacent the inert anode in order to minimize corrosion by substances in the bath. A particularly preferred cell produces aluminum by electrolysis of alumina in a molten salt bath containing aluminum fluoride and sodium fluoride.

  18. Molten salt bath circulation design for an electrolytic cell

    DOEpatents

    Dawless, R.K.; LaCamera, A.F.; Troup, R.L.; Ray, S.P.; Hosler, R.B.

    1999-08-17

    An electrolytic cell for reduction of a metal oxide to a metal and oxygen has an inert anode and an upwardly angled roof covering the inert mode. The angled roof diverts oxygen bubbles into an upcomer channel, thereby agitating a molten salt bath in the upcomer channel and improving dissolution of a metal oxide in the molten salt bath. The molten salt bath has a lower velocity adjacent the inert anode in order to minimize corrosion by substances in the bath. A particularly preferred cell produces aluminum by electrolysis of alumina in a molten salt bath containing aluminum fluoride and sodium fluoride. 4 figs.

  19. Fluoride availability from natural resources in The Gambia--implications for oral health care.

    PubMed

    Jordan, Rainer A; Markovic, Ljubisa; Gaengler, Peter

    2008-10-01

    Changing food patterns in combination with ineffective oral hygiene measures and insufficient bioavailability of fluoride from drinking water and other sources seem to impair the dental health status in developing countries, especially in the younger population. Therefore, preventive programmes in controlling dental caries progression should be based on local conditions. For mapping the drinking water fluoride content throughout The Gambia, samples of water from rural community wells, public water taps, commercial mineral water, and from the Gambia-River were measured. Additionally, fluoride concentrations of locally extracted table salt and green tea were determined. Showed the need for supplementary fluoride intake, because natural dietary fluoride availability is very low. Age-related recommendations for oral health care and for additional fluoride bioavailability are given, taking into account local socio-economic conditions in the Republic of The Gambia and similar developing countries.

  20. 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 ...

  1. Fluoridation: strategies for success.

    PubMed Central

    Isman, R

    1981-01-01

    Of 19 referenda on community water fluoridation held in the first six months of 1980, 17 were defeated. Among the postulated reasons are a growing distrust of government and the health establishment. The public remains largely ignorant of the purpose and benefits of fluoridation. The emotionalism surrounding the issue has made it difficult to generate public support outside of the health professions. Opponents have also learned to fight fluoridation with increasingly sophisticated techniques. Some of the strategies used in recent successful campaigns in Oakland, California, and Portland, Oregon are described; recommendations that can be applied to communities considering fluoridation include careful wording of ballot measures so they are unequivocally clear and simple; timing ballot measures with elections likely to draw the largest voter turnout; broadening the base of political and financial support; using a figurehead if possible; and making maximum use of the media. PMID:7246838

  2. 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 ...

  3. Fluoridation: strategies for success.

    PubMed

    Isman, R

    1981-07-01

    Of 19 referenda on community water fluoridation held in the first six months of 1980, 17 were defeated. Among the postulated reasons are a growing distrust of government and the health establishment. The public remains largely ignorant of the purpose and benefits of fluoridation. The emotionalism surrounding the issue has made it difficult to generate public support outside of the health professions. Opponents have also learned to fight fluoridation with increasingly sophisticated techniques. Some of the strategies used in recent successful campaigns in Oakland, California, and Portland, Oregon are described; recommendations that can be applied to communities considering fluoridation include careful wording of ballot measures so they are unequivocally clear and simple; timing ballot measures with elections likely to draw the largest voter turnout; broadening the base of political and financial support; using a figurehead if possible; and making maximum use of the media.

  4. 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.

  5. Caries inhibitory effect of fluoridated sugar in a trial in Indonesia.

    PubMed

    Mulyani, D; McIntyre, J

    2002-12-01

    In some regional areas of Indonesia, caries prevalence is increasing rapidly. As water, salt or milk fluoridation were not considered suitable for use throughout Indonesia, and fluoridated tooth paste is mostly too expensive, a fluoride co-crystallised sugar containing 10 ppm fluoride was prepared. Its efficacy in inhibiting caries development was tested in a field trial. The field trial was established in Medan, Sumatera. All dietary background data necessary to ensure the safety of a trial were collected. Subjects chosen were 176 children who were residents of two orphanages and a boarding school for children of poor rural families. The trial used a double-blind format. Close monitoring of fluoride consumption was maintained, and fluoride excretion rates were assessed six monthly by urinary fluoride analysis. Records of total tooth surface caries present initially and after 18 months of sugar supply showed that the children using fluoridated sugar had significantly fewer carious lesions than those who used normal sugar. This result indicates that sugar might be considered as a further vehicle for supplementary dietary fluoride in communities where there is a high caries prevalence or high caries risk and little exposure to fluoride.

  6. Hot filament technique for measuring the thermal conductivity of molten lithium fluoride

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Perry, William D.

    1990-01-01

    Molten salts, such as lithium fluoride, are attractive candidates for thermal energy storage in solar dynamic space power systems because of their high latent heat of fusion. However, these same salts have poor thermal conductivities which inhibit the transfer of heat into the solid phase and out of the liquid phase. One concept for improving the thermal conductivity of the thermal energy storage system is to add a conductive filler material to the molten salt. High thermal conductivity pitch-based graphite fibers are being considered for this application. Although there is some information available on the thermal conductivity of lithium fluoride solid, there is very little information on lithium fluoride liquid, and no information on molten salt graphite fiber composites. This paper describes a hot filament technique for determining the thermal conductivity of molten salts. The hot filament technique was used to find the thermal conductivity of molten lithium fluoride at 930 C, and the thermal conductivity values ranged from 1.2 to 1.6 W/mK. These values are comparable to the slightly larger value of 5.0 W/mK for lithium fluoride solid. In addition, two molten salt graphite fiber composites were characterized with the hot filament technique and these results are also presented.

  7. Developments in Molten Salt and Liquid-Salt-Cooled Reactors

    SciTech Connect

    Forsberg, Charles W.

    2006-07-01

    In the last 5 years, there has been a rapid growth in interest in the use of high-temperature (700 to 1000 deg C) molten and liquid fluoride salts as coolants in nuclear systems. This renewed interest is a consequence of new applications for high-temperature heat and the development of new reactor concepts. Fluoride salts have melting points between 350 and 500 deg C; thus, they are of use only in high-temperature systems. Historically, steam cycles with temperature limits of {approx}550 deg C have been the only efficient method to convert heat to electricity. This limitation produced few incentives to develop high-temperature reactors for electricity production. However, recent advances in Brayton gas turbine technology now make it possible to convert higher-temperature heat efficiency into electricity on an industrial scale and thus have created the enabling technology for more efficient nuclear reactors. Simultaneously, there is a growing interest in using high-temperature nuclear heat for the production of hydrogen and shale oil. Five nuclear-related applications are being investigated: (1) liquid-salt heat-transport systems in hydrogen and shale oil production systems; (2) the advanced high-temperature reactor, which uses a graphite-matrix coated-particle fuel and a liquid salt coolant; (3) the liquid-salt-cooled fast reactor which uses metal-clad fuel and a liquid salt coolant; (4) the molten salt reactor, with the fuel dissolved in the molten salt coolant; and (5) fusion energy systems. The reasons for the new interest in liquid salt coolants, the reactor concepts, and the relevant programs are described. (author)

  8. 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.

  9. 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.

  10. Recovery of protactinium from molten fluoride nuclear fuel compositions

    DOEpatents

    Baes, C.F. Jr.; Bamberger, C.; Ross, R.G.

    1973-12-25

    A method is provided for separating protactinium from a molten fluonlde salt composition consisting essentially of at least one alkali and alkaline earth metal fluoride and at least one soluble fluoride of uranium or thorium which comprises oxidizing the protactinium in said composition to the + 5 oxidation state and contacting said composition with an oxide selected from the group consisting of an alkali metal oxide, an alkaline earth oxide, thorium oxide, and uranium oxide, and thereafter isolating the resultant insoluble protactinium oxide product from said composition. (Official Gazette)

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

    PubMed

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

    2017-01-20

    The efficacy and safety of combined use of topical fluoride products are essential issues that must be monitored. To assess urinary excretion of fluoride after application of two different dental varnishes containing 2.26% fluoride in 3- to 4-year-old children and to compare the levels with and without parallel use of fluoride toothpaste. Fifteen healthy children were enrolled to a randomized crossover trial that was performed in two parts: Part I with twice-daily tooth brushing with fluoride toothpaste and Part II with twice-daily brushing with a non-fluoride toothpaste. After a 1-week run-in period, 0.1 mL of the two fluoride varnishes (Duraphat and Profluorid Varnish) was topically applied in a randomized order. Baseline and experimental urine was collected during 6-h periods. The fluoride content was determined with an ion-sensitive electrode. There was a statistically significant increase in the 6-h fluoride excretion after application of both experimental varnishes, with and without parallel use of fluoride toothpaste (P < 0.01). When fluoridated toothpaste was used, the mean fluoride excretion was 0.20 mg/6 h after application of Duraphat and 0.29 mg/6 h after application of Profluorid Varnish (P = 0.18). Topical applications of 0.1 mL of fluoride varnish significantly increased the 6-h fluoride excretion. As some individuals displayed excretion levels exceeding the optimal fluoride exposure, a restricted use of fluoride toothpaste in connection with the varnish applications would decrease fluoride exposure. © 2017 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

    PubMed

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

    2015-09-01

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

  13. Fluoride-containing restorative materials.

    PubMed

    Burke, F M; Ray, N J; McConnell, R J

    2006-02-01

    Dental practitioners are exposed to an increasing number of dental materials, which claim the benefits of fluoride release. The purpose of this paper is to critically review the literature of these materials. Glass ionomers, resin modified glass ionomers, compomers, resin composites, fissure sealants and amalgam are discussed. It is clear that a long-term measurable release of fluoride can be observed from certain restorative materials, in vitro, particularly glass ionomer cement, resin modified glass ionomer cement, fluoridated cements, fluoridated dental amalgam and certain fissure sealants. In general, the rate of fluoride release is not constant but exhibits a relatively rapid initial rate, which decreases with time. However, the fluoride release profiles may be dependent on specific formulation and on experimental design and sampling methods. These materials may feature greater longevity, a reduced incidence of marginal failure, an elevated concentration of fluoride in contingent plaque, together with an antibacterial action when compared with non-fluoride releasing materials. In addition, fluoride-releasing materials may perform better in caries inhibition in artificial caries model studies than non-fluoridated materials. While any, or all, of these anti-cariogenic effects may be associated with fluoride release, a direct relationship between fluoride release profiles and such effects has not been determined in vivo.

  14. Fluoride release from fluoride varnishes under acidic conditions.

    PubMed

    Lippert, F

    2014-01-01

    The aim was to investigate the in vitro fluoride release from fluoride varnishes under acidic conditions. Poly(methyl methacrylate) blocks (Perspex, n=3 per group) were painted with 80 ± 5 mg fluoride varnish (n=10) and placed into artificial saliva for 30 min. Then, blocks were placed into either 1% citric acid (pH 2.27) or 0.3% citric acid (pH 3.75) solutions (n=3 per solution and varnish) for 30 min with the solutions being replaced every 5 min. Saliva and acid solutions were analyzed for fluoride content. Data were analyzed using three-way ANOVA (varnish, solution, time). The three-way interaction was significant (p>0.0001). Fluoride release and release patterns varied considerably between varnishes. Fluoride release in saliva varied by a factor of more than 10 between varnishes. Some varnishes (CavityShield, Nupro, ProFluorid, Vanish) showed higher fluoride release in saliva than during the first 5 min of acid exposure, whereas other varnishes (Acclean, Enamel-Pro, MI Varnish, Vella) showed the opposite behavior. There was little difference between acidic solutions. Fluoride release from fluoride varnishes varies considerably and also depends on the dissolution medium. Bearing in mind the limitations of laboratory research, the consumption of acidic drinks after fluoride varnish application should be avoided to optimize the benefit/risk ratio.

  15. 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.

  16. Intake and metabolism of fluoride.

    PubMed

    Whitford, G M

    1994-06-01

    The purpose of this paper is to discuss the major factors that determine the body burden of inorganic fluoride. Fluoride intake 25 or more years ago was determined mainly by measurement of the concentration of the ion in the drinking water supply. This is not necessarily true today because of ingestion from fluoride-containing dental products, the "halo effect", the consumption of bottled water, and the use of water purification systems in the home. Therefore, the concentration of fluoride in drinking water may not be a reliable indicator of previous intake. Under most conditions, fluoride is rapidly and extensively absorbed from the gastrointestinal tract. The rate of gastric absorption is inversely related to the pH of the gastric contents. Overall absorption is reduced by calcium and certain other cations and by elevated plasma fluoride levels. Fluoride removal from plasma occurs by calcified tissue uptake and urinary excretion. About 99% of the body burden of fluoride is associated with calcified tissues, and most of it is not exchangeable. In general, the clearance of fluoride from plasma by the skeleton is inversely related to the stage of skeletal development. Skeletal uptake, however, can be positive or negative, depending on the level of fluoride intake, hormonal status, and other factors. Dentin fluoride concentrations tend to increase throughout life and appear to be similar to those in bone. Research to determine whether dentin is a reliable biomarker for the body burden of fluoride is recommended. The renal clearance of fluoride is high compared with other halogens. It is directly related to urinary pH. Factors that acidify the urine increase the retention of fluoride and vice versa. The renal clearance of fluoride decreases and tissue levels increase when the glomerular filtration rate is depressed on a chronic basis.

  17. Fluoride in weathered rock aquifers of southern India: Managed Aquifer Recharge for mitigation.

    PubMed

    Brindha, K; Jagadeshan, G; Kalpana, L; Elango, L

    2016-05-01

    Climatic condition, geology, and geochemical processes in an area play a major role on groundwater quality. Impact of these on the fluoride content of groundwater was studied in three regions-part of Nalgonda district in Telangana, Pambar River basin, and Vaniyar River basin in Tamil Nadu, southern India, which experience semi-arid climate and are predominantly made of Precambrian rocks. High concentration of fluoride in groundwater above 4 mg/l was recorded. Human exposure dose for fluoride through groundwater was higher in Nalgonda than the other areas. With evaporation and rainfall being one of the major contributors for high fluoride apart from the weathering of fluoride rich minerals from rocks, the effect of increase in groundwater level on fluoride concentration was studied. This study reveals that groundwater in shallow environment of all three regions shows dilution effect due to rainfall recharge. Suitable managed aquifer recharge (MAR) methods can be adopted to dilute the fluoride rich groundwater in such regions which is explained with two case studies. However, in deep groundwater, increase in fluoride concentration with increase in groundwater level due to leaching of fluoride rich salts from the unsaturated zone was observed. Occurrence of fluoride above 1.5 mg/l was more in areas with deeper groundwater environment. Hence, practicing MAR in these regions will increase the fluoride content in groundwater and so physical or chemical treatment has to be adopted. This study brought out the fact that MAR cannot be practiced in all regions for dilution of ions in groundwater and that it is essential to analyze the fluctuation in groundwater level and the fluoride content before suggesting it as a suitable solution. Also, this study emphasizes that long-term monitoring of these factors is an important criterion for choosing the recharge areas.

  18. 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

  19. 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.

  20. 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)

  1. 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

  2. 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

  3. 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)

  4. Other Fluoride Products

    MedlinePlus

    ... About CDC.gov . Oral Health home Oral Health Basics Children's Oral Health Protecting Your Child's Teeth Brush Up on Healthy Teeth Adult Oral Health ... concentration of fluoride in a small amount of material in close contact with the teeth for many hours. Varnishes must be reapplied at ...

  5. Fluoride Consumption and Its Impact on Oral Health

    PubMed Central

    Jiménez-Farfán, María Dolores; Hernández-Guerrero, Juan Carlos; Juárez-López, Lilia Adriana; Jacinto-Alemán, Luis Fernando; de la Fuente-Hernández, Javier

    2011-01-01

    Objective The purpose of this study was to evaluate caries and dental fluorosis among Mexican preschoolers and school-aged children in a non-endemic zone for fluorosis and to measure its biological indicators. Methods DMFT, DMFS, dmft, dmfs, and CDI indexes were applied. Fluoride urinary excretion and fluoride concentrations in home water, table salt, bottled water, bottled drinks, and toothpaste were determined. Results Schoolchildren presented fluorosis (CDI = 0.96) and dental caries (DMFT = 2.64 and DMFS = 3.97). Preschoolers presented dmft = 4.85 and dmfs = 8.80. DMFT and DMFS were lower in children with mild to moderate dental fluorosis (DF). Variable fluoride concentrations were found in the analyzed products (home water = 0.18–0.44 ppm F, table salt = 0–485 ppm F, bottled water = 0.18–0.47 ppm F, juices = 0.08–1.42 ppm F, nectars = 0.07–1.30 ppm F, bottled drinks = 0.10–1.70 ppm F, toothpaste = 0–2,053 ppm F). Mean daily fluoride excretion was 422 ± 176 μg/24 h for schoolchildren and 367 ± 150 μg/24 h for preschoolers. Conclusions Data from our study show that, despite values of excretion within an optimal fluoride intake range, the prevalence of caries was significant in both groups, and 60% of the 11- to 12-year-old children presented with dental fluorosis. In addition, variable fluoride concentrations in products frequently consumed by children were found. PMID:21318021

  6. 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.

  7. Long-range transport of fluoride in East Asia monitored at Noto Peninsula, Japan.

    PubMed

    Yang, Xiao-Yang; Yamada, Maromu; Tang, Ning; Lin, Jin-Ming; Wang, Wei; Kameda, Takayuki; Toriba, Akira; Hayakawa, Kazuichi

    2009-08-01

    Airborne particulate matter was collected at Wajima, the Noto Peninsula, Ishikawa, Japan by a high-volume air sampler with a quartz fiber filter every week from September 17, 2004 to September 16, 2005. The filter was newly changed every week. There are no major emission sources of atmospheric pollutants near the sampling site. Water-soluble fluoride anion extracted from the filters was analyzed by ion chromatography. The concentration of non-sea-salt fluoride was higher during the heating period of China (from October 15, 2004 to April 15, 2005), significantly higher during the period of Asian Dust (from the mid of April to the beginning of May in 2005), than that in the other seasons. This result suggests that the main contributor of fluoride in the period of Asian Dust was high-fluoride-concentrated soil from the arid area of China. A noticeable positive correlation (r=0.54, n=28, p<0.01) between the level of non-sea-salt fluoride and PAHs was observed, when only the data obtained during the period of Asian Dust was excluded. In view of the fact that PAHs emitted from Northeast China were long-range transported to Japan during the heating period of China, fluoride emitted from coal combustion long-range transported from the Asian continent to Japan during the same period appears to be another main source of fluoride.

  8. 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.

  9. 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)

  10. Use of fluorides in dental caries management.

    PubMed

    Chu, C H; Mei, May L; Lo, Edward C M

    2010-01-01

    Fluoride is commonly and widely used to prevent and even arrest caries. The clinical effects of fluorides depend on the chemical compounds utilized and the methods used to apply the fluoride ion to the surface of the tooth. Fluorosis has been reported in conjunction with increased doses of fluoride. A coordinated approach to fluoride delivery is essential to avoid the risk of fluorosis.

  11. 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)

  12. Water fluoridation and oral health.

    PubMed

    Harding, Máiréad Antoinette; O'Mullane, Denis Martin

    2013-11-01

    Water fluoridation, is the controlled addition of fluoride to the water supply, with the aim of reducing the prevalence of dental caries. Current estimates suggest that approximately 370 million people in 27 countries consume fluoridated water, with an additional 50 million consuming water in which fluoride is naturally occurring. A pre-eruptive effect of fluoride exists in reducing caries levels in pit and fissure surfaces of permanent teeth and fluoride concentrated in plaque and saliva inhibits the demineralisation of sound enamel and enhances the remineralisation of demineralised enamel. A large number of studies conducted worldwide demonstrate the effectiveness of water fluoridation. Objections to water fluoridation have been raised since its inception and centre mainly on safety and autonomy. Systematic reviews of the safety and efficacy of water fluoridation attest to its safety and efficacy; dental fluorosis identified as the only adverse outcome. Water fluoridation is an effective safe means of preventing dental caries, reaching all populations, irrespective of the presence of other dental services. Regular monitoring of dental caries and fluorosis is essential particularly with the lifelong challenge which dental caries presents. Copyright © 2013 by Academy of Sciences and Arts of Bosnia and Herzegovina.

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

    PubMed

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

    2014-08-01

    Interim and definitive restorations cemented with interim cements for a prolonged interval are susceptible to bacterial infiltration and caries formation. The purpose of this in vitro study was to evaluate the long-term fluoride release and solubility of aged ZnO-based interim cements enriched separately with 0.4% NaF and SnF2. Four different brands of cements (Tempbond, Tempbond NE, Procem, and Freegenol) were tested for fluoride release and solubility. For every test, 6 disk specimens of each cement with NaF and SnF2, and 6 with no fluoride enrichment (control) were fabricated, for a total of 72 specimens. The disks were incubated in deionized water. Fluoride ion release was recorded at 1, 7, 14, 21, 63, 91, and 182 days. Solubility was calculated as weight percent after 90 days of incubation. The data were analyzed by analysis of variance with repeated measures and the Tukey honestly significant difference post hoc test (P<.05). Cements mixed with fluorides released fluoride ions for at least 182 days. Cements mixed with NaF released more fluoride ions than those mixed with SnF2 (P<.001). The cumulative release rates from all the tested cements mixed with either NaF or SnF2 were linear with respect to t(½) (r>.97), indicating a diffusion-controlled fluoride release. Cement and fluoride types were the main affecting factors in fluoride ion release. The addition of fluorides slightly increased the solubility of the cements. Given their long-term sustained and diffusive controlled release, these fluorides, particularly NaF when mixed with ZnO-based interim cements, may be useful for caries prevention under provisionally cemented restorations. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. A review on fluoride varnishes: an alternative topical fluoride treatment.

    PubMed

    Clark, D C

    1982-06-01

    The in vitro, in vivo and clinical research on topical fluoride varnishes in surveyed. The probable mechanisms of action for fluoride varnishes is discussed and this effect demonstrated from the results of in vitro and in vivo research. Findings from clinical studies are summarized and selected results are used to estimate expected preventive effects from the treatment. The practical advantages and limitations of fluoride varnishes are also reviewed and indications for the future used of these preventive agents are considered.

  15. 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.

  16. Magnesium fluoride recovery method

    SciTech Connect

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

    1989-10-17

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

  17. Magnesium fluoride recovery method

    SciTech Connect

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

    1989-10-17

    This patent describes a method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag formed in the production of metallic uranium by the reduction of depleted uranium tetrafluoride with metallic magnesium in a retort wherein the slag contains the free metals magnesium and uranium and also oxides and fluorides of the metals, the slag having a radioactivity level of at least about 7,000 pCi/gm. The method comprises: grinding the slag to a median particle size of about 200 microns; contacting the ground slag in a reaction zone with an acid having a strength of from about 0.5 to 1.5 N for a time of from about 4 to about 20 hours in the presence of a catalytic amount of iron, the reaction zone being maintained at a temperature within the range of from about 60{degrees} to 90{degrees} C. and the weight of ratio of slag to acid being within the range of from about 1:2 to 1:6 to produce a liquid product and a particulate solid product; removing the liquid product; treating the particulate solid product; and repeating steps at least one more time to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 pCi/gm.

  18. Young children and fluoride toothpaste.

    PubMed

    Rock, W P

    1994-07-09

    Studies have shown a higher prevalence of enamel mottling in children who live in fluoridated areas than in those from low fluoride areas. It is possible that the additive effect of fluoride ingestion from water and toothpaste may be responsible since it is known that young children may swallow up to half of the toothpaste on the brush. Parents must supervise toothbrushing for young children, low fluoride paste should be used, and the brush merely smeared with paste. The commonly recommended pea-sized quantity may be too much.

  19. [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.

  20. 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

  1. INNER SALTS

    DTIC Science & Technology

    been characterized include: (1) mesomeric phosphonium salts possessing phototropic properties; (2) pentavalent phosphorus compounds; and (3) a...Products that have been characterized include: (1) mesomeric phosphonium salts possessing phototropic properties; (2) pentavalent phosphorus compounds; and (3) a mesomeric inner salt. (Author)

  2. 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.

  3. 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

  4. Enhanced enamel benefits from a novel toothpaste and dual phase gel containing calcium silicate and sodium phosphate salts.

    PubMed

    Hornby, Kate; Ricketts, Stephen R; Philpotts, Carole J; Joiner, Andrew; Schemehorn, Bruce; Willson, Richard

    2014-06-01

    To investigate the enamel health benefits of a novel toothpaste and a dual phase gel containing calcium silicate, sodium phosphate and fluoride. Enamel demineralisation was assessed using two pH cycling protocols with either lactic acid or citric acid as the acid challenge. Remineralisation of lactic acid softened and citric acid softened enamel was assessed using a number of protocols. All demineralisation and remineralisation evaluation was by surface microhardness measurements. The novel calcium silicate/phosphate fluoride toothpaste inhibited enamel demineralisation to a significantly (p<0.05) greater extent than control formulations, including a fluoride control. The novel calcium silicate/phosphate fluoride toothpaste also showed significant (p<0.05) remineralisation of lactic acid and citric acid softened enamel compared to fluoride and non-fluoride controls. The addition of the novel calcium silicate/phosphate fluoride dual phase gel provided enhanced remineralisation of citric acid softened enamel compared to fluoride and non-fluoride controls. These studies show that formulations containing calcium silicate, sodium phosphate salts and fluoride provide enhanced enamel demineralisation and remineralisation in vitro benefits. The novel oral care formulations containing calcium silicate, sodium phosphate salts and fluoride is a new approach to the protection of enamel from acid attacks and the repair of demineralised enamel, leading to increased dental hard tissue benefits. © 2014 Elsevier Ltd. All rights reserved.

  5. 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.

  6. Effect of impurities in industrial salts on aluminum scrap melting

    SciTech Connect

    Ye, J.; Sahai, Y.; Revet, A.

    1996-10-01

    Aluminum scrap such as Used Beverage Containers (UBC) is melted under a protective molten salt cover. An appropriate salt protects metal from oxidation, promotes coalescence of molten droplets, and separates clean metal from the oxide contamination. Generally, the salt compositions for aluminum scrap recycling are based on equimolar mixtures of NaCl and KCl. A small amount of fluoride is also added in the salt. In the past, laboratory research at universities and industrial laboratories have been limited to pure salts. However, the industrial salts have impurities such as sulfates and other insoluble materials. These impurities have a pronounced effect on the efficiency of the scrap remelting process. In this paper, the role of impurities in industrial salts in terms of their chemical interactions with the metal are summarized. The efficiency of different industrial grade salts containing varying amounts of sulfates and other insoluble impurities for scrap recycling is compared.

  7. 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.

  8. Tealeaves may release or absorb fluoride, depending on the fluoride content of water.

    PubMed

    Malde, Marian Kjellevold; Greiner-Simonsen, Rita; Julshamn, Kåre; Bjorvatn, Kjell

    2006-08-01

    As the tea plant (Camellia sinensis) is known to accumulate fluoride from the soil, the tealeaves may contain high concentrations of fluoride, which is easily released during infusion. In this study, we have tested the possible effect of original fluoride concentration in the water on the fluoride release from tea. Moreover, we wanted to test the possible capacity of tealeaves (commercially available tea) to absorb fluoride from high-fluoride water. In low-fluoride water, fluoride is easily released from tealeaves. Depending upon the fluoride content of the water, dried tealeaves are able also to absorb fluoride. Thus, if a cup of tea is made from high-fluoride water, the fluoride concentration of the infusion may actually be lower than the original fluoride concentration of the water.

  9. Compatibility of molten salts with advanced solar dynamic receiver materials

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Metal-coated graphite fibers are being considered as a thermal conductivity enhancement filler material for molten salts in solar dynamic thermal energy storage systems. The successful metal coating chosen for this application must exhibit acceptable wettability and must be compatible with the molten salt environment. Contact angle values between molten lithium fluoride and several metal, metal fluoride, and metal oxide substrates have been determined at 892 C using a modification of the Wilhelmy plate technique. Reproducible contact angles with repeated exposure to the molten LiF indicated compatibility.

  10. WET FLUORIDE SEPARATION METHOD

    DOEpatents

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

    1958-11-25

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

  11. Fluoride removal performance of a novel Fe-Al-Ce trimetal oxide adsorbent.

    PubMed

    Wu, Xiaomei; Zhang, Yu; Dou, Xiaomin; Yang, Min

    2007-11-01

    A trimetal oxide was developed as a fluoride adsorbent by coprecipitation of Fe(II), Al(III) and Ce(IV) salt solutions with a molar ratio of 1:4:1 under alkaline condition. The material retained amorphous structure and maintained relatively stable fluoride adsorption performance at calcination temperatures lower than 600 degrees C. The optimum pH range for fluoride adsorption was 6.0-6.5 and the adsorbent also showed high defluoridation ability around pH 5.5-7.0, which is preferable for actual application. A high fluoride adsorption capacity of 178 mg g(-1) was acquired under an equilibrium fluoride concentration of 84.5 mg l(-1), adsorbent dose of 150 mg l(-1) and pH 7.0. The adsorption isotherm could be better described by the two-site Langmuir model than the one-site model, suggesting the existence of two types of active sites on the adsorbent surface. Coexistence of high concentrations of phosphate or arsenate only led to partial inhibition of fluoride adsorption, which further suggests the existence of heterogeneous adsorption sites. Sulfate and chloride did not affect fluoride adsorption, and nitrate influenced it only when the concentration of NO(3)(-)-N exceeded 50 mg l(-1). A high desorption efficiency of 97% was achieved by treating fluoride loaded Fe-Al-Ce oxide with NaOH solution at pH 12.2. A column experiment using the adsorbent fabricated into 1mm pellets was performed at an initial fluoride concentration of 5.5 mg l(-1), space velocity of 5h(-1) and pH of 5.8, and 2240 bed volumes were treated with the effluent fluoride under 1.0 mg l(-1).

  12. Topical fluoride for caries prevention

    PubMed Central

    Weyant, Robert J.; Tracy, Sharon L.; Anselmo, Theresa (Tracy); Beltrán-Aguilar, Eugenio D.; Donly, Kevin J.; Frese, William A.; Hujoel, Philippe P.; Iafolla, Timothy; Kohn, William; Kumar, Jayanth; Levy, Steven M.; Tinanoff, Norman; Wright, J. Timothy; Zero, Domenick; Aravamudhan, Krishna; Frantsve-Hawley, Julie; Meyer, Daniel M.

    2015-01-01

    Background A panel of experts convened by the American Dental Association (ADA) Council on Scientific Affairs presents evidence-based clinical recommendations regarding professionally applied and prescription-strength, home-use topical fluoride agents for caries prevention. These recommendations are an update of the 2006 ADA recommendations regarding professionally applied topical fluoride and were developed by using a new process that includes conducting a systematic review of primary studies. Types of Studies Reviewed The authors conducted a search of MEDLINE and the Cochrane Library for clinical trials of professionally applied and prescription-strength topical fluoride agents—including mouthrinses, varnishes, gels, foams and pastes—with caries increment outcomes published in English through October 2012. Results The panel included 71 trials from 82 articles in its review and assessed the efficacy of various topical fluoride caries-preventive agents. The panel makes recommendations for further research. Practical Implications The panel recommends the following for people at risk of developing dental caries: 2.26 percent fluoride varnish or 1.23 percent fluoride (acidulated phosphate fluoride) gel, or a prescription-strength, home-use 0.5 percent fluoride gel or paste or 0.09 percent fluoride mouthrinse for patients 6 years or older. Only 2.26 percent fluoride varnish is recommended for children younger than 6 years. The strengths of the recommendations for the recommended products varied from “in favor” to “expert opinion for.” As part of the evidence-based approach to care, these clinical recommendations should be integrated with the practitioner's professional judgment and the patient's needs and preferences. PMID:24177407

  13. Effect of sodium fluoride on the morphological picture of the rat liver exposed to NaF in drinking water.

    PubMed

    Dabrowska, E; Letko, R; Balunowska, M

    2006-01-01

    Due to its efficacy in caries prophylaxis and easy application, sodium fluoride (NaF) is still used for caries prevention in the form of fluoridated drinking water, fluoride tablets, fluoridated salt or milk. Effect of fluorides on various metabolic levels in hard and soft tissues, namely respiration as well as carbohydrate, protein, enzymatic and vascular metabolism, can disturb detoxication of fluorine compounds administered orally. The study objective was morphological examination of the liver of young and mature rats exposed to NaF in drinking water from conception till maturity, as well as after its withdrawal. In the initial stage of the experiment, 30 female Wistar rats, 180-200 g body weight, were divided into 3 groups: one control and two experimental groups (I, II). Female rats in the experimental groups received fluorine in aqueous solutions of sodium fluoride (NaF) at a concentration of 10.6 mg NaF/dm3 (group I) and 32.0 mg NaF/dm3 (group II). The pathomorphological changes observed in the liver, particularly of young rats exposed,to fluorides at superoptimal doses can help determine to what degree oral fluoride caries prevention is safe and whether it should be implemented. The transitory nature of pathomorphological changes in hepatocytes indicates adaptive potentials or defence mechanisms against orally administered sodium fluoride.

  14. 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.

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  16. 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…

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. Advantages of liquid fluoride thorium reactor in comparison with light water reactor

    NASA Astrophysics Data System (ADS)

    Bahri, Che Nor Aniza Che Zainul; Majid, Amran Ab.; Al-Areqi, Wadeeah M.

    2015-04-01

    Liquid Fluoride Thorium Reactor (LFTR) is an innovative design for the thermal breeder reactor that has important potential benefits over the traditional reactor design. LFTR is fluoride based liquid fuel, that use the thorium dissolved in salt mixture of lithium fluoride and beryllium fluoride. Therefore, LFTR technology is fundamentally different from the solid fuel technology currently in use. Although the traditional nuclear reactor technology has been proven, it has perceptual problems with safety and nuclear waste products. The aim of this paper is to discuss the potential advantages of LFTR in three aspects such as safety, fuel efficiency and nuclear waste as an alternative energy generator in the future. Comparisons between LFTR and Light Water Reactor (LWR), on general principles of fuel cycle, resource availability, radiotoxicity and nuclear weapon proliferation shall be elaborated.

  2. Advantages of liquid fluoride thorium reactor in comparison with light water reactor

    SciTech Connect

    Bahri, Che Nor Aniza Che Zainul Majid, Amran Ab.; Al-Areqi, Wadeeah M.

    2015-04-29

    Liquid Fluoride Thorium Reactor (LFTR) is an innovative design for the thermal breeder reactor that has important potential benefits over the traditional reactor design. LFTR is fluoride based liquid fuel, that use the thorium dissolved in salt mixture of lithium fluoride and beryllium fluoride. Therefore, LFTR technology is fundamentally different from the solid fuel technology currently in use. Although the traditional nuclear reactor technology has been proven, it has perceptual problems with safety and nuclear waste products. The aim of this paper is to discuss the potential advantages of LFTR in three aspects such as safety, fuel efficiency and nuclear waste as an alternative energy generator in the future. Comparisons between LFTR and Light Water Reactor (LWR), on general principles of fuel cycle, resource availability, radiotoxicity and nuclear weapon proliferation shall be elaborated.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  5. 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.

  6. Synthesis of fluoride-releasing carbonate apatites for bone substitutes.

    PubMed

    Sogo, Yu; Ito, Atsuo; Yokoyama, Daiki; Yamazaki, Atsushi; LeGeros, Racquel Z

    2007-06-01

    Fluoride (F-)-substituted B-type carbonate hydroxyapatite (CHAP) powders were prepared for application as bone substitute materials having the ability to enhance bone formation and to suppress bone resorption due to the therapeutic effect of F-. F- was adsorbed on CHAP in a sodium fluoride solution followed by heating at 700 degrees C in carbon dioxide flow to substitute F- for the hydroxyl ion in the CHAP structure. The F- contents in the F-substituted CHAP powders were 16-22 times greater than that in normal adult human bones. The carbonate ion contents in the F-substituted CHAP powders corresponded to or were higher than that in normal adult human bones. F-substituted CHAP powder with CO3(2-) and F- contents of 11.03 and 0.66 wt%, respectively, slowly released F- in a physiological salt solution to a sufficiently high F- level. The F- concentration slowly increased and reached 67.20 +/- 4.81 microg l(-1), which was 1.5-9.3 times higher than that in the body fluid of normal adult humans, near the therapeutic window of F-, and far lower than the estimated toxic level. Therefore, the F-substituted CHAP can promote bone formation. The present F-substituted CHAP has the advantage of slow F- release over sodium fluoride and sodium monofluorophosphate which are highly soluble salts and cannot be sintered into a ceramic body.

  7. Analytical chemistry of aluminum salt cake

    SciTech Connect

    Graczyk, D.G.; Essling, A.M.; Huff, E.A.; Smith, F.P.; Snyder, C.T.

    1997-02-01

    Component phases of Al salt cake or products from processing salt cake, resist dissolution, a key first step in most analysis procedures. In this work (analysis support to a study of conversion of salt cake fines to value-added oxide products), analysis methods were adapted or devised for determining leachable salt, total halides (Cl and F), Al metal, and elemental composition. Leaching of salt cake fines was by ultrasonic agitation with deionized water. The leachate was analyzed for anions by ion chromatography and for cations by ICP-atomic emission spectroscopy. Only chloride could be measured in the anions, and charge balances between cations and chloride were near unity, indicating that all major dissolved species were chloride salts. For total halides, the chloride and fluorides components were first decomposed by KOH fusion, and the dissolved chloride and fluoride were measured by ion chromatography. Al metal in the fines was determined by a hydrogen evolution procedure adapted for submilligram quantities of metallic Al: the Al was reacted with HCl in a closed system containing a measured amount of high-purity He. After reaction, the H/He ratio was measured by mass spectroscopy. Recoveries of Al metal standards (about 30mg) averaged 93%. Comparison of the acid evolution with caustic reaction of the Al metal showed virtually identical results, but reaction was faster in the acid medium. Decomposition of the salt cake with mineral acids left residues that had to be dissolved by fusion with Na carbonate. Better dissolution was obtained by fusing the salt cake with Li tetraborate; the resulting solution could be used for accurate Al assay of salt cake materials by classical 8-hydroxyquinolate gravimetry.

  8. 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.

  9. 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

  10. Portland Water Fluoridation: A Newspaper Analysis.

    PubMed

    Bianchi, Allison; Bergren, Martha Dewey; Lewis, Patricia Ryan

    2017-03-01

    Portland, Oregon is the largest city in the United States without community water fluoridation (CWF). A newspaper analysis was conducted of the failed 2013 CWF campaign to evaluate anti-fluoridation and pro-fluoridation messaging provided by newspapers during the campaign. News content was categorized by type and slant (pro-fluoridation, anti-fluoridation, or neutral) and 34 variables were tabulated (23 anti-fluoridation, 11 pro-fluoridation). Results showed overall messaging was slightly pro-fluoridation, as compared to anti-fluoridation or neutral content (35%, 32%, and 33% respectively). Editorial content was 85% pro-fluoridation and 15% anti-fluoridation. The most frequent anti-fluoridation variables were alternatives to water fluoridation, mass/forced medication and concerns about the political process. Conversely, tooth decay and social justice were the most commonly cited pro-fluoridation variables. Newspapers can be influential in shaping public policy opinions in the fight for community water fluoridation. © 2016 Wiley Periodicals, Inc.

  11. Fluoride release from aged resin composites containing fluoridated glass filler.

    PubMed

    Itota, Toshiyuki; Al-Naimi, Omar T; Carrick, Thomas E; Yoshiyama, Masahiro; McCabe, John F

    2005-11-01

    The aim of this study was to evaluate the fluoride release from aged resin composites containing different types of fluoridated glass filler into both deionized distilled water and lactic acid solution. Three resin composites, UniFil S (containing fluoro-alumino-silicate glass filler), Reactmer (containing pre-reacted glass-ionomer filler) and Beautifil (containing both types of fillers) were used. A conventional glass-ionomer cement, Ketac-Fil, was used as a control. Five disk specimens of each material were prepared and aged in water for 10 weeks. After aging, specimens were immersed in deionized distilled water for a further 6 days and then in aqueous lactic acid (pH 4.0) for 2 days. This process was repeated twice more and the specimens were subsequently immersed in water for a further 12 days. Fluoride release was measured every 2 days throughout the post-aging period. The amount of fluoride release for aged UniFil S and Beautifil markedly increased in acid solution compared with water storage. The difference was not so great for aged Reactmer and Ketac-Fil. UniFil S and Beautifil gave significantly greater fluoride release in water following immersion in acid solution (p<0.05, two-way ANOVA and Scheffe's test), but Reactmer and Ketac-Fil showed no such increase in fluoride release after acid immersion. These results suggested that the nature of the fluoridated glass filler within a resin composite and the way in which the material interacts with an acidic environment affected the amount of fluoride released.

  12. Beryllium Interactions in Molten Salts

    SciTech Connect

    G. S. Smolik; M. F. Simpson; P. J. Pinhero; M. Hara; Y. Hatano; R. A. Anderl; J. P. Sharpe; T. Terai; S. Tanaka; D. A. Petti; D.-K. Sze

    2006-01-01

    Molten flibe (2LiF·BeF2) is a candidate as a cooling and tritium breeding media for future fusion power plants. Neutron interactions with the salt will produce tritium and release excess free fluorine ions. Beryllium metal has been demonstrated as an effective redox control agent to prevent free fluorine, or HF species, from reacting with structural metal components. The extent and rate of beryllium solubility in a pot design experiments to suppress continuously supplied hydrogen fluoride gas has been measured and modeled[ ]. This paper presents evidence of beryllium loss from specimens, a dependence of the loss upon bi-metal coupling, i.e., galvanic effect, and the partitioning of the beryllium to the salt and container materials. Various posttest investigative methods, viz., scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) were used to explore this behavior.

  13. 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.

  14. 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.

  15. 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)

  16. 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)

  17. Aminodifluorosulfinium Tetrafluoroborate Salts as Stable and Crystalline Deoxofluorinating Reagents

    PubMed Central

    2009-01-01

    Aminodifluorosulfinium tetrafluoroborate salts were found to act as efficient deoxofluorinating reagents when promoted by an exogenous fluoride source and, in most cases, exhibited greater selectivity by providing less elimination byproduct as compared to DAST and Deoxo-Fluor. Aminodifluorosulfinium tetrafluoroborates are easy handled crystalline salts that show enhanced thermal stability over dialkylaminosulfur trifluorides, are storage-stable, and unlike DAST and Deoxo-Fluor do not react violently with water. PMID:19799406

  18. Distribution coefficients of vitamin B2 in hydrophilic organic solvent-aqueous salt solution systems

    NASA Astrophysics Data System (ADS)

    Korenman, Ya. I.; Mokshina, N. Ya.; Zykov, A. V.

    2010-03-01

    Distribution coefficients of vitamin B2 in hydrophilic solvent ( n-butanol, isopropanol, acetone, ethyl acetate, and their mixtures)-aqueous salt (potassium chloride, sodium fluoride, and ammonium sulfate salting-out agents) solution systems were calculated. The synergic effect and optimum proportions of components in the solvent mixture for efficient extraction of vitamin B2 from aqueous solutions were established.

  19. The synthesis and structural characterization of novel transition metal fluorides

    SciTech Connect

    Casteel, W.J. Jr.

    1992-09-01

    High purity KMF[sub 6] and K[sub 2]MF[sub 6] salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF[sub 6]. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF[sub 4] is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF[sub 4] type cell are derived from X-ray powder data for ReF[sub 4] and OsF[sub 4]. Fluoride ion capture from KAgF[sub 4] provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF[sub 3] and redetermination of the AuF[sub 3] structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF[sub 3] is the mixed valence compound Ag[sup II]Ag[sub 2][sup III]F[sub 8]. Several new salts containing the (Ag - F)[sub n][sup n+] chain cation are prepared. The first linear (Ag - F)[sub n][sup n+] chain is observed in AgF[sup +]BF[sub 4 [sup [minus

  20. Viscosity of molten lithium, thorium and beryllium fluorides mixtures

    NASA Astrophysics Data System (ADS)

    Merzlyakov, Alexander V.; Ignatiev, Victor V.; Abalin, Sergei S.

    2011-12-01

    Considering development of Molten Salt Fast Reactor (MSFR) concept, following Molten Salt fluorides mixtures have been chosen as an object for viscosity studies in this work (in mol%): 78LiF-22ThF 4; 71LiF-27ThF 4-2BeF 2 and 75LiF-20ThF 4-5BeF 2. Additionally, the effect of the 3 mol% CeF 3 additives on viscosity of the molten 75LiF-20ThF 4-5BeF 2 (mol%) salt mixture has been investigated experimentally. The method of torsional oscillations of cylindrical crucible filled by molten fluorides mixture has been chosen for kinematic viscosity measurement at temperatures up to 800-850 °C. In temperature ranges, where melts behave as normal liquids, dependences on viscosity vs. temperature are received: ν = А exp [B/T(K)], where ν - kinematic viscosity, m 2/s; T - temperature, K. The kinematic viscosity Rout mean squares (RMS) estimated in the assumption about dispersion homoscedasticity is (0.04-0.12) × 10 -6 (m 2/s). Discrepancies left in the data of viscosity for molten mixtures of LiF, BeF 2 and ThF 4 received by different researchers need further investigations in this area to be continued.

  1. Selective Activation of Fluoroalkenes with N-Heterocyclic Carbenes: Synthesis of N-Heterocyclic Fluoroalkenes and Polyfluoroalkenyl Imidazolium Salts.

    PubMed

    Leclerc, Matthew C; Gorelsky, Serge I; Gabidullin, Bulat M; Korobkov, Ilia; Baker, R Tom

    2016-06-06

    Selective reactions between nucleophilic N,N'-diaryl-heterocyclic carbenes (NHCs) and electrophilic fluorinated alkenes afford NHC fluoroalkenes in high yields. These stable compounds undergo efficient and selective fluoride abstraction with Lewis acids to give polyfluoroalkenyl imidazolium salts. These salts react at Cβ with pyrrolidine to give ammonium fluoride-substituted salts, which give rise to conjugated imidazolium-enamine salts through loss of HF. Alternatively, reaction with 4-(dimethylamino)-pyridine provides a Cα-pyridinium-substituted NHC fluoroalkene. These compounds were studied using multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. Insight into their electronic structure and reactivity was gained through the use of DFT calculations.

  2. Chemistry and technology of Molten Salt Reactors - history and perspectives

    NASA Astrophysics Data System (ADS)

    Uhlíř, Jan

    2007-01-01

    Molten Salt Reactors represent one of promising future nuclear reactor concept included also in the Generation IV reactors family. This reactor type is distinguished by an extraordinarily close connection between the reactor physics and chemical technology, which is given by the specific features of the chemical form of fuel, representing by molten fluoride salt and circulating through the reactor core and also by the requirements of continuous 'on-line' reprocessing of the spent fuel. The history of Molten Salt Reactors reaches the period of fifties and sixties, when the first experimental Molten Salt Reactors were constructed and tested in ORNL (US). Several molten salt techniques dedicated to fresh molten salt fuel processing and spent fuel reprocessing were studied and developed in those days. Today, after nearly thirty years of discontinuance, a renewed interest in the Molten Salt Reactor technology is observed. Current experimental R&D activities in the area of Molten Salt Reactor technology are realized by a relatively small number of research institutions mainly in the EU, Russia and USA. The main effort is directed primarily to the development of separation processes suitable for the molten salt fuel processing and reprocessing technology. The techniques under development are molten salt/liquid metal extraction processes, electrochemical separation processes from the molten salt media, fused salt volatilization techniques and gas extraction from the molten salt medium.

  3. Fluoride bioavailability in saliva and plaque

    PubMed Central

    2012-01-01

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

  4. Studies of fluoride varnishes in Finland.

    PubMed

    Seppä, L

    1991-01-01

    Despite the artificial fluoridation of drinking water in Kuopio, part of the children have high caries incidence. We therefore started our studies on fluoride varnishes in 1977 in an attempt to find a feasible means of applying fluoride topically in children at high risk of caries. In our first trial, the sodium fluoride varnish Duraphat was found to be effective in preventing caries, but the effectiveness of the silane fluoride varnish Fluor Protector could not be unequivocally established, despite the fact that Fluor Protector deposited markedly more fluoride in enamel than Duraphat. In a second study in children in a low-fluoride area, use of Duraphat was found to be more effective than fortnightly fluoride rinses or Fluor Protector. Increasing the frequency of application from two to four times a year did not increase the effectiveness of Duraphat even in highly caries-prone children in a 2-year trial. On the basis of peak values of fluoride in parotid saliva after application, use of either fluoride varnishes was considered safe. Although the fluoride content of the enamel remained elevated for at least two years after discontinuation of treatment with both varnishes, the caries preventive effect did not continue after the applications were stopped. This shows that increasing the fluoride content of enamel is not the main mechanism by which fluoride varnishes prevent caries, and that the applications need to be continued as long as caries is a problem.

  5. Health effects of groundwater fluoride contamination.

    PubMed

    Nayak, Bishwajit; Roy, Madan Mohan; Das, Bhaskar; Pal, Arup; Sengupta, Mrinal Kumar; De, Shankar Prasad; Chakraborti, Dipankar

    2009-04-01

    The people in Berhait block, Sahibganj district, Jharkhand state, India, have been exposed chronically to fluoridecontaminated groundwater. Hereby, we report the clinical effects of chronic exposure to fluoride. The study population was a convenience sample of 342 adults and 258 children living in the affected area. All volunteers filled out questionnaires and were examined. Well water from the six affected villages and urine samples were analyzed for fluoride using an ion-sensitive electrode. Twenty nine percent of 89 well water samples had fluoride concentrations above the Indian permissible limit of fluoride in drinking water. Eighty-five children and 72 adults had clinical fluorosis. Urine fluoride concentrations in children were 0.758-2.88 mg/L whereas in adults they were 0.331-10.36 mg/L. Clinical effects of fluoride included abnormal tooth enamel in children; adults had joint pain and deformity of the limbs and spine, along with ligamentous calcifications and exostosis formations in seven patients. Elevated urine fluoride concentrations supported the clinical diagnosis of fluorosis. Owing to insufficient fluoride-safe wells and lack of awareness of the danger of fluoride toxicity, villagers often drink fluoride-contaminated water. Villagers of Berhait block, including children, are at risk from chronic fluoride toxicity. To combat the situation, villagers need fluoride-safe water, education, and awareness of the danger about fluoride toxicity.

  6. Fluoride content of tank water in Australia.

    PubMed

    Cochrane, N J; Hopcraft, M S; Tong, A C; Thean, H l; Thum, Y S; Tong, D E; Wen, J; Zhao, S C; Stanton, D P; Yuan, Y; Shen, P; Reynolds, E C

    2014-06-01

    The aims of this study were to: (1) analyse the fluoride content of tank water; (2) determine whether the method of water collection or storage influenced fluoride content; and (3) survey participant attitudes towards water fluoridation. Plastic tubes and a questionnaire were distributed through dentists to households with water tanks in Victoria. A midstream tank water sample was collected and fluoride analysed in triplicate using ion chromatography All samples (n = 123) contained negligible amounts of fluoride, with a mean fluoride concentration of <0.01 ppm (range: <0.01-0.18 ppm). No statistically significant association was found between fluoride content and variables investigated such as tank material, tank age, roof material and gutter material. Most people did not know whether their tank water contained fluoride and 40.8% preferred to have access to fluoridated water. The majority thought fluoride was safe and more than half of the respondents supported fluoridation. Fluoride content of tank water was well below the optimal levels for caries prevention. People who rely solely on tank water for drinking may require additional exposure to fluoride for optimal caries prevention. © 2014 Australian Dental Association.

  7. 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

  8. 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

  9. 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. Copyright © 2011 S. Karger AG, Basel.

  10. Cladding Alloys for Fluoride Salt Compatibility Final Report

    SciTech Connect

    Muralidharan, Govindarajan; Wilson, Dane F; Santella, Michael L; Holcomb, David Eugene

    2011-05-01

    This interim report provides an overview of several candidate technologies for cladding nickel-based corrosion protection layers onto high-temperature structural alloys. The report also provides a brief overview of the welding and weld performance issues associated with joining nickel-clad nickel-based alloys. From the available techniques, two cladding technologies were selected for initial evaluation. The first technique is a line-of-sight method that would be useful for coating large structures such as vessel interiors or large piping. The line-of-sight method is a laser-based surface cladding technique in which a high-purity nickel powder mixed into a polymer binder is first sprayed onto the surface, baked, and then rapidly melted using a high power laser. The second technique is a vapor phase technique based on the nickel-carbonyl process that is suitable for coating inaccessible surfaces such as the interior surfaces of heat exchangers. The final project report will feature an experimental evaluation of the performance of the two selected cladding techniques.

  11. Fluoride mouthrinses for preventing dental caries in children and adolescents.

    PubMed

    Marinho, Valeria C C; Chong, Lee Yee; Worthington, Helen V; Walsh, Tanya

    2016-07-29

    Fluoride mouthrinses have been used extensively as a caries-preventive intervention in school-based programmes and by individuals at home. This is an update of the Cochrane review of fluoride mouthrinses for preventing dental caries in children and adolescents that was first published in 2003. The primary objective is to determine the effectiveness and safety of fluoride mouthrinses in preventing dental caries in the child and adolescent population.The secondary objective is to examine whether the effect of fluoride rinses is influenced by:• initial level of caries severity;• background exposure to fluoride in water (or salt), toothpastes or reported fluoride sources other than the study option(s); or• fluoride concentration (ppm F) or frequency of use (times per year). We searched the following electronic databases: Cochrane Oral Health's Trials Register (whole database, to 22 April 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 3), MEDLINE Ovid (1946 to 22 April 2016), Embase Ovid (1980 to 22 April 2016), CINAHL EBSCO (the Cumulative Index to Nursing and Allied Health Literature, 1937 to 22 April 2016), LILACS BIREME (Latin American and Caribbean Health Science Information Database, 1982 to 22 April 2016), BBO BIREME (Bibliografia Brasileira de Odontologia; from 1986 to 22 April 2016), Proquest Dissertations and Theses (1861 to 22 April 2016) and Web of Science Conference Proceedings (1990 to 22 April 2016). We undertook a search for ongoing trials on the US National Institutes of Health Trials Register (http://clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform. We placed no restrictions on language or date of publication when searching electronic databases. We also searched reference lists of articles and contacted selected authors and manufacturers. Randomised or quasi-randomised controlled trials where blind outcome assessment was stated or

  12. Dental fluorosis: concentration of fluoride in drinking water and consumption of bottled beverages in school children.

    PubMed

    Pérez-Pérez, N; Torres-Mendoza, N; Borges-Yáñez, A; Irigoyen-Camacho, M E

    2014-01-01

    The purpose of the study was to identify dental fluorosis prevalence and to analyze its association with tap water fluoride concentration and beverage consumption in school children from the city of Oaxaca, who were receiving fluoridated salt. A cross-sectional study was performed on elementary public school children. Dean's Index was applied to assess dental fluorosis. The parents of the children who were studied completed a questionnaire about socio-demographic characteristics and type of beverages consumed by their children. A total of 917 school children participated in this study. Dental fluorosis prevalence was 80.8%. The most frequent fluorosis category was very mild (41.0%), and 16.4% of the children were in the mild category. The mean water fluoride concentration was 0.43 ppm (±0.12). No association was detected between tap water fluoride concentration and fluorosis severity. The multinomial regression model showed an association among the mild fluorosis category and age (OR = 1.25, [95% CI 1.04, 1.50]) and better socio-economic status (OR = 1.78, [95% CI 1.21, 2.60]), controlling for fluoride concentration in water. Moderate and severe fluorosis were associated with soft drink consumption (OR = 2.26, [95% IC 1.01, 5.09]), controlling for age, socio-economic status, and water fluoride concentration. The prevalence of fluorosis was high. Mild fluorosis was associated with higher socio-economic status, while higher fluorosis severity was associated with soft drink consumption.

  13. Crystal Structures of Diaryliodonium Fluorides and their Implications for Fluorination Mechanisms.

    PubMed

    Lee, Yong Sok; Chun, Joong-Hyun; Hodošček, Milan; Pike, Victor

    2017-01-31

    The radiofluorination of diaryliodonium salts is of value for producing radiotracers for positron emission tomography. We report crystal structures for two diaryliodonium fluorides. Whereas diphenyliodon um fluoride (1a) exists as a tetramer bridged by four fluoride ions, 2-methylphenyl(phenyl)iodonium fluoride (2a) forms a fluoride-bridged dimer that is further halogen-bonded to two other monomers. We discuss the topological relationships between the two and their implications for fluorination in solution. Both radiofluorination and NMR spectroscopy show that thermolysis of 2a gives 2-fluorotoluene and fluorobenzene in a 2 to 1 ratio that is in good agreement with the ratio observed from the radiofluorination of 2-methylphenyl(phenyl)iodonium chloride (2b). The constancy of the product ratio affirms that the fluorinations occur via the same two rapidly interconverting transition states whose energy difference dictates chemoselectivity. The quantum chemical studies with density functional theory at the level of B3LYP/DGDZVP provide deeper insight into the role of 'ortho effect' in the mechanism of fluorination. By utilizing the crystal structures of 1a and 2a, the mechanisms of fluoroarene formation from diaryliodonium fluorides in their monomeric, homodimeric, heterodimeric, and tetrameric states were also investigated. According to this analysis, we propose that oligomerization energy dictates whether the fluorination occurs through a monomeric or an oligomeric pathway.

  14. Novel graphite salts of high oxidizing potential

    SciTech Connect

    McCarron, E.M. III

    1980-08-01

    The intercalation of graphite by the third-transition-series metal hexafluorides has yielded the graphite salts, C/sub 8//sup +/OsF/sub 6//sup -/, C/sub 8//sup +/IrF/sub 6//sup -/ and C/sub 12//sup 2 +/PtF/sub 6//sup 2 -/. The fluoroplatinate salt represents the highest electron withdrawal from the graphite network yet achieved. Analogues to the Os and Ir salts have been obtained both by fluorination of Group V pentaflouride intercalates, C/sub 8/MF/sub 5/ (M = As, Sb), and by the interaction of the dioxygenyl salts with graphite (8C + O/sub 2/MF/sub 6/ ..-->.. C/sub 8/MF/sub 6/ + O/sub 2/+). Non-intercalating binary fluorides have been observed to intercalate in the presence of a fluorine-rich environment (e.g., 8C + PF/sub 5/ + 1/2 F/sub 2/ ..-->.. C/sub 8/PF/sub 6/). GeF/sub 4/, which also does not spontaneously intercalate graphite, has been observed to interact with graphite in the presence of 2 atmospheres of fluorine overpressure to give the fluoroplatinate salt analogue, C/sub 12//sup 2 +/GeF/sub 6//sup 2 -/. This material is in equilibrium with the pentafluorogermanate at ordinary pressures and temperatures. C/sub 12//sup 2 +/GeF/sub 6//sup 2 -/ ..-->.. C/sub 12//sup +/GeF/sub 5//sup -/ + 1/2 F/sub 2/. C/sub 12/GeF/sub 6/ must have an oxidizing potential close to that of fluorine itself. The graphite fluorometallate salts are both electronic and ionic (F/sup -/) conductors. For the C/sub 8//sup +/MF/sub 6//sup -/ salts, a maximum electronic conductivity an order of magnitude greater than the parent graphite has been observed for stage two. The high oxidizing potential, coupled with the fluoride ion transport capability of the graphite salts, has been exploited in the construction of solid-state galvanic cells. These cells use the graphite fluorometallate salts as electrode materials in combination with a superionic fluoride-ion-conducting solid electrolyte.

  15. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... the cylinder's water weight capacity. In place of the periodic volumetric expansion test, cylinders...

  16. [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.

  17. Lebanese children are iodine deficient and urinary sodium and fluoride excretion are weak positive predictors of urinary iodine.

    PubMed

    Ghattas, Hala; Francis, Sirine; El Mallah, Carla; Shatila, Dareen; Merhi, Karina; Hlais, Sani; Zimmermann, Michael; Obeid, Omar

    2017-03-01

    To assess iodine and fluoride status among Lebanese children. A nationally representative cross-sectional study of 6- to 10-year-old schoolchildren was conducted using multistage cluster sampling. Spot urine samples were collected from 1403 children, and urinary iodine, fluoride, creatinine and sodium levels were measured. Salt samples from markets (n = 30) were tested for iodine concentration by titration. Median urinary iodine concentration was 66.0 µg/l, indicating mild deficiency, and almost 75 % of Lebanese children had a urinary iodine concentration (UIC) <100 µg/l. UIC was higher among children from private schools and in areas of higher socioeconomic status. Most salt samples were fortified at levels far below the legislated requirement, and 56 % of samples contained less than 15 ppm iodine. Fluoride-to-creatinine ratio (F/Cr) was 0.250 (0.159-0.448) mg/g. There were weak positive correlations between UIC and urinary sodium (r (2) = 0.039, P value <0.001) and UIC and urinary fluoride (r (2) = 0.009, P value <0.001). Lebanese elementary school children are iodine deficient due to inadequately iodized salt. The weak correlation between UIC and urinary sodium suggests most dietary iodine does not come from iodized salt. The poor correlation between UIC and urinary fluoride suggests that fluoride intake is not affecting iodine metabolism. Efforts are needed in Lebanon to improve industry compliance with salt fortification through improved monitoring and enforcement of legislation.

  18. Acute toxicity of uranium hexafluoride, uranyl fluoride and hydrogen fluoride

    SciTech Connect

    Just, R.A.

    1988-01-01

    Uranium hexafluoride (UF/sub 6/) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO/sub 2/F/sub 2/) and hydrogen fluoride (HF). Uranium compounds such as UF/sub 6/ and UO/sub 2/F/sub 2/ exhibit both chemical toxicity and radiological effects, while HF exhibits only chemical toxicity. This paper describes the development of a methodology for assessing the human health consequences of a known acute exposure to a mixture of UF/sub 6/, UO/sub 2/F/sub 2/, and HF. 4 refs., 2 figs., 5 tabs.

  19. 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)

  20. 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)

  1. 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…

  2. 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)

  3. 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.

  4. 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.

  5. 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.

  6. Vitrification of IFR and MSBR halide salt reprocessing wastes

    SciTech Connect

    Siemer, D.D.

    2013-07-01

    Both of the genuinely sustainable (breeder) nuclear fuel cycles (IFR - Integral Fast Reactor - and MSBR - Molten Salt Breeder Reactor -) studied by the USA's national laboratories would generate high level reprocessing waste (HLRW) streams consisting of a relatively small amount ( about 4 mole %) of fission product halide (chloride or fluoride) salts in a matrix comprised primarily (about 95 mole %) of non radioactive alkali metal halide salts. Because leach resistant glasses cannot accommodate much of any of the halides, most of the treatment scenarios previously envisioned for such HLRW have assumed a monolithic waste form comprised of a synthetic analog of an insoluble crystalline halide mineral. In practice, this translates to making a 'substituted' sodalite ('Ceramic Waste Form') of the IFR's chloride salt-based wastes and fluoroapatite of the MSBR's fluoride salt-based wastes. This paper discusses my experimental studies of an alternative waste management scenario for both fuel cycles that would separate/recycle the waste's halide and immobilize everything else in iron phosphate (Fe-P) glass. It will describe both how the work was done and what its results indicate about how a treatment process for both of those wastes should be implemented (fluoride and chloride behave differently). In either case, this scenario's primary advantages include much higher waste loadings, much lower overall cost, and the generation of a product (glass) that is more consistent with current waste management practices. (author)

  7. Void control in the crystallization of lithium fluoride

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Perry, William D.

    1991-01-01

    The effect of tungsten-coated graphite fibers on the radiant heat transfer characteristics of salt-fiber composites was studied by measuring the onset of melting as a function of applied furnace power. As the fiber concentration was increased from 0 to 5.40 percent fiber by weight, the furnace temperature required to melt the lithium fluoride also increased. Upon cooling, each of the crystalline salt-fiber composites were cut open with a diamond saw to expose the void. Optical photographs of the voids revealed a trend in void location and size, with the largest void, and the least change in the outer dimension of the boule upon cooling, occurring in the sample with the most fiber.

  8. Community-oriented administration of fluoride for the prevention of dental caries: a summary of the current situation in Asia.

    PubMed

    Petersen, P E; Baez, R J; Lennon, M A

    2012-02-01

    Dental caries is the most prevalent chronic disease affecting human populations around the world. It is recognized that fluoride plays a significant role in dental caries reduction. Meanwhile, several low- and middle-income countries of Asia have not yet implemented systematic fluoride programs; contributing factors relate to misconceptions about the mechanisms of fluoride, low priority given to oral health in national health policy and strategic plans, and lack of interest among public health administrators. A workshop on the effective use of fluoride in Asia took place in Phang-Nga, Thailand, in 2011. A series of country presentations addressed some of the topics mentioned above; in addition, speakers from countries of the region provided examples of successful fluoride interventions and discussed program limitations, barriers encountered, and solutions, as well as possibilities for expanding coverage. Participants acknowledged that automatic fluoridation through water, salt, and milk is the most effective and equitable strategy for the prevention of dental caries. Concerns were expressed that government-subsidized community fluoride prevention programs may face privatization. In addition, the use of affordable fluoride-containing toothpastes should be encouraged. The workshop identified: strengths and weaknesses of ongoing community-based fluoride programs, as well as the interest of countries in a particular method; the requirement for World Health Organization (WHO) technical assistance on various aspects, including fluoridation process, feasibility studies, and implementation of effective epidemiological surveillance of the program; exchange of information; and the need for inter-country collaboration. It was acknowledged that program process and evaluation at the local and country levels need further dissemination. The meeting was co-sponsored by the World Health Organization, the International Association for Dental Research, and the World Dental Federation.

  9. The synthesis and structural characterization of novel transition metal fluorides

    SciTech Connect

    Casteel, Jr., William Jack

    1992-09-01

    High purity KMF6 and K2MF6 salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF6. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF4 is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF4 type cell are derived from X-ray powder data for ReF4 and OsF4. Fluoride ion capture from KAgF4 provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF3 and redetermination of the AuF3 structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF3 is the mixed valence compound AgIIAg2IIIF8. Several new salts containing the (Ag - F)$n+\\atop{n}$ chain cation are prepared. The first linear (Ag - F)$n+\\atop{n}$ chain is observed in AgF+BF4- which crystallizes in a tetragonal unit. AgFAuF4 has a triclinic unit cell and is isostructural with CuFAuF4. AgFAuF6 has an orthorhombic unit cell and appears to be isostructural with AgFAsF6. A second mixed valence silver fluoride, AgIIAgIIIF5, is prepared, which magnetic measurements indicate is probably an AgF+ salt. Magnetic data for all of the AgF+ salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic AG(II) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(II) and O2 to O2+. Reactions with C6F6 and C3F6 suggest an electron capture

  10. The synthesis and structural characterization of novel transition metal fluorides

    NASA Astrophysics Data System (ADS)

    Casteel, W. J., Jr.

    1992-09-01

    High purity KMF6 and K2MF6 salts (M = Mo, Re, Ru, Os, Ir, and Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF6. Fluoride ion capture by Lewis acids from the hexafluorometallate(IV)salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF4 is determined from x-ray synchrotron and neutron powder data. Unit cells based on the orthorhombic PdF4 type cell are derived from x-ray powder data for ReF4 and OsF4. Fluoride ion capture from KAgF4 provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF3 and redetermination of the AuF3 structure from x-ray synchrotron and neutron powder data demonstrate that the two are isostructural. The thermal decomposition product of AgF3 is the mixed valence compound Ag(+2)Ag2(+3)F8. Several new salts containing the (Ag-F)n(n+) chain cation are prepared. The first linear (Ag-F)n(n+) chain is observed in AgF(+)BF4(-) which crystallizes in a tetragonal unit. AgFAuF4 has a triclinic unit cell and is isostructural with CuFAuF4. AgFAuF6 has an orthorhombic unit cell and appears to be isostructural with AgFAsF6. A second mixed valence silver fluoride, Ag(+2)Ag(+3)F5, is prepared, which magnetic measurements indicate is probably an AgF(+) salt. Magnetic data for all of the AgF(+) salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic Ag(+3) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(+2) and O2 to O2(+). Reactions with C6F and C3F6 suggest an electron capture mechanism for cationic Ag(+2) oxidations.

  11. Water fluoridation as a public health measure.

    PubMed

    McGrady, Michael G; Ellwood, Roger P; Pretty, Iain A

    2010-12-01

    Water fluoridation schemes have been used as dental public health measures for over 50 years. This second paper in a series of three aims to provide a background to the history of water fluoridation schemes and the evidence base that led to their implementation. The article will also discuss the processes and chemicals involved in fluoridation during water treatment. This article aims to provide a summary for general practitioners of the history and evidence base for water fluoridation, to enable them to understand the role of water fluoridation in caries prevention and to be able to answer non-clinical questions raised by patients.

  12. 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. © 2013 Eur J Oral Sci.

  13. Oxidative aliphatic C-H fluorination with fluoride ion catalyzed by a manganese porphyrin.

    PubMed

    Liu, Wei; Huang, Xiongyi; Cheng, Mu-Jeng; Nielsen, Robert J; Goddard, William A; Groves, John T

    2012-09-14

    Despite the growing importance of fluorinated organic compounds in drug development, there are no direct protocols for the fluorination of aliphatic C-H bonds using conveniently handled fluoride salts. We have discovered that a manganese porphyrin complex catalyzes alkyl fluorination by fluoride ion under mild conditions in conjunction with stoichiometric oxidation by iodosylbenzene. Simple alkanes, terpenoids, and even steroids were selectively fluorinated at otherwise inaccessible sites in 50 to 60% yield. Decalin was fluorinated predominantly at the C2 and C3 methylene positions. Bornyl acetate was converted to exo-5-fluoro-bornyl acetate, and 5α-androstan-17-one was fluorinated selectively in the A ring. Mechanistic analysis suggests that the regioselectivity for C-H bond cleavage is directed by an oxomanganese(V) catalytic intermediate followed by F delivery via an unusual manganese(IV) fluoride that has been isolated and structurally characterized.

  14. Water fluoridation, osteoporosis, fractures--recent developments.

    PubMed

    Demos, L L; Kazda, H; Cicuttini, F M; Sinclair, M I; Fairley, C K

    2001-06-01

    Optimal (1ppm) water fluoridation is seen as the most socially equitable way to prevent dental caries, however concerns about the safety of fluoridation are periodically raised. Research on effects on bone published since the 1991 National Health and Medical Research Council report on water fluoridation was reviewed. Thirty-three studies were identified. Adverse effects in animal feeding studies were only seen at doses much greater than those currently used in artificial water fluoridation. The majority of animal studies showed no effect or a beneficial effect of low fluoride doses. The results of ecological studies were conflicting. One of the two cohort studies showed an increase in fracture incidence at fluoride levels four times greater than optimal water fluoridation and the other showed no effect after 20 years' optimal fluoridation. The cross-sectional studies showed a favourable effect on bone mineral density. The clinical trials predominantly showed increased bone density in several sites associated with fluoride treatment of 9-22.6mg fluoride per day for one-four years. These studies provide a substantial body of evidence that fluoride at up to 1ppm does not have an adverse effect on bone strength, bone mineral density or fracture incidence.

  15. Total and soluble fluoride content in commercial dentifrices in Chile.

    PubMed

    Carrera, Carola A; Giacaman, Rodrigo A; Muñoz-Sandoval, Cecilia; Cury, Jaime A

    2012-12-01

    Regardless of the total amount of fluoride (F) in a dentifrice, only the soluble fraction presents anti-caries activity and its concentration must be above 1000 ppm. No information regarding the quality of F in Chilean toothpastes is available. The aim of this study, therefore, was to determine the F concentration present in commercially-available toothpastes in Chile. Eighteen toothpastes of five different brands were tested, each purchased from three different chain drugstores in Chile. For each toothpaste, total, total soluble and ionic F concentrations were assessed and expressed as ppm of F (μg F/g). Among the dentifrices evaluated, 77.8% contained NaF (sodium fluoride), 16.7% MFP (monofluorphosphate) and 5.6% both types of F salts; 77.2% of the dentifrices showed similar total F content to that declared by the manufacturer in the labeling with only five with lower concentration than expected, beyond a 5% disagreement tolerance range. Total soluble F ranged from 958.8-1496.3 ppm (mean ± SD: 1270.5 ± 183.7). Five toothpastes showed lower total soluble F than total F. Only one toothpaste showed soluble salt levels below the recommended dose for this type of dentifrice. Most Chilean dentifrices evaluated contained soluble F within the range of 1000-1500 ppm and, therefore, may have anti-caries activity.

  16. Unusual hydrogen bonding in L-cysteine hydrogen fluoride.

    PubMed

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

    2015-08-01

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

  17. The role of fluoride in erosion therapy.

    PubMed

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

    2014-01-01

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

  18. Water fluoridation in Canada: past and present.

    PubMed

    Rabb-Waytowich, Danielle

    2009-07-01

    Water fluoridation remains a contentious issue in Canada and many communities choose not to fluoridate their water supply. As of 2007, 45.1% of the Canadian population had access to fluoridated water supplies. The main arguments for and against fluoridation have changed very little over the years, with supporters (including the World Health Organization and Health Canada) citing evidence that shows fluoridation as a safe and effective method of caries prevention, while detractors cite high costs and potential health risks. This article provides an historical overview and a current snapshot of water fluoridation in Canada. It concludes that the ultimate advantage of fluoridation is that it helps everyone in a community, regardless of socioeconomic status.

  19. Phosphate salts

    MedlinePlus

    ... taken by mouth or used as enemas. Indigestion. Aluminum phosphate and calcium phosphate are FDA-permitted ingredients ... Phosphate salts containing sodium, potassium, aluminum, or calcium are LIKELY SAFE for most people when taken by mouth short-term, when sodium phosphate is inserted into the ...

  20. Preliminary Safeguards Assessment for the Pebble-Bed Fluoride High-Temperature Reactor (PB-FHR) Concept

    SciTech Connect

    Disser, Jay; Arthur, Edward; Lambert, Janine

    2016-09-01

    This report examines a preliminary design for a pebble bed fluoride salt-cooled high temperature reactor (PB-FHR) concept, assessing it from an international safeguards perspective. Safeguards features are defined, in a preliminary fashion, and suggestions are made for addressing further nuclear materials accountancy needs.

  1. 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.

  2. 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)

  3. 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)

  4. 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.

  5. Determining the optimal fluoride concentration in drinking water for fluoride endemic regions in South India.

    PubMed

    Viswanathan, Gopalan; Jaswanth, A; Gopalakrishnan, S; Siva Ilango, S; Aditya, G

    2009-10-01

    Fluoride ion in drinking water is known for both beneficial and detrimental effects on health. The prevalence of fluorosis is mainly due to the intake of large quantities of fluoride through drinking water owing to more than 90% bioavailability. The objective of this study is to predict optimal fluoride level in drinking water for fluoride endemic regions by comprising the levels of fluoride and other water quality parameters in drinking water, prevalence of fluorosis, fluoride intake through water, food and beverages such as tea and coffee and also considering the progressive accumulation of fluoride in animal bones, by comparing with non fluoride endemic areas comprise of the same geological features with the aid of regression analysis. Result of this study shows that increase of fluoride level above 1.33 mg/l in drinking water increases the community fluorosis index (CFI) value more than 0.6, an optimum index value above which fluorosis is considered to be a public health problem. Regression plot between water fluoride and bone fluoride levels indicates that, every increase of 0.5mg/l unit of water fluoride level increases the bone fluoride level of 52 mg/kg unit within 2 to 3 years. Furthermore, the consumption of drinking water containing more than 0.65 mg/l of fluoride can raise the total fluoride intake per day more than 4 mg, which is the optimum fluoride dose level recommended for adults by the Agency for Toxic Substances and Disease Registry. From the result, the people in fluoride endemic areas in South India are advised to consume drinking water with fluoride level within the limit of 0.5 to 0.65 mg/l to avoid further fluorosis risk.

  6. Alimentary fluoride intake in preschool children

    PubMed Central

    2011-01-01

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

  7. 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

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

    PubMed

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

    2016-01-05

    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.

  9. 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

  10. 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

  11. Molten salts and nuclear energy production

    NASA Astrophysics Data System (ADS)

    Le Brun, Christian

    2007-01-01

    Molten salts (fluorides or chlorides) were considered near the beginning of research into nuclear energy production. This was initially due to their advantageous physical and chemical properties: good heat transfer capacity, radiation insensitivity, high boiling point, wide range solubility for actinides. In addition it was realised that molten salts could be used in numerous situations: high temperature heat transfer, core coolants with solid fuels, liquid fuel in a molten salt reactor, solvents for spent nuclear solid fuel in the case of pyro-reprocessing and coolant and tritium production in the case of fusion. Molten salt reactors, one of the six innovative concepts chosen by the Generation IV international forum, are particularly interesting for use as either waste incinerators or thorium cycle systems. As the neutron balance in the thorium cycle is very tight, the possibility to perform online extraction of some fission product poisons from the salt is very attractive. In this article the most important questions that must be addressed to demonstrate the feasibility of molten salt reactor will be reviewed.

  12. 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)...

  13. Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

    PubMed

    Bolis, Carlo; Härtli, Gian Peider; Lendenmann, Urs

    2015-01-01

    Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release. Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison. After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 μg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 μg F·cm-². The other products ranged between 12-16 μg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 μg F·cm-², respectively. The fluoride uptake of these two products was not statistically different. Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

  14. 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

  15. Focus on fluorides: update on the use of fluoride for the prevention of dental caries.

    PubMed

    Carey, Clifton M

    2014-06-01

    Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure. 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. 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. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    PubMed

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

    2007-03-01

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

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

    PubMed Central

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

    2013-01-01

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

  18. 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.

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

    PubMed

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

    2010-06-30

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

  20. 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... FLUORIDE F 18 injection, 10 to 200 mCi/mL, if all other legal and regulatory requirements are met. FOR...

  1. Fluoride content of infant formulae in Australia.

    PubMed

    Silva, M; Reynolds, E C

    1996-02-01

    The prevalence of dental fluorosis in Australia and the United States of America has increased in both optimally fluoridated and non-fluoridated areas. This has been attributed to an increase in the fluoride level of food and beverages through processing with fluoridated water, inadvertent ingestion of fluoride toothpaste, and the inappropriate use of dietary supplements. A major source of fluoride in infancy is considered to be infant formula which has been implicated as a risk factor for fluorosis in a number of studies. In this study the fluoride content of the infant formulae commonly used in Australia was determined. The acid diffusible fluoride of each powdered formula was isolated by microdiffusion and measured using a fluoride ion-specific electrode. The fluoride content of milk-based formulae ranged from 0.23 to 3.71 micrograms F/g and for soy-based formulae from 1.08 to 2.86 micrograms F/g. When reconstituted, according to the manufacturer's directions, with water not containing fluoride, the formulae ranged in fluoride content from 0.031 to 0.532 ppm, with the average fluoride content 0.240 ppm. Using average infant body masses and suggested volumes of formula consumption for infants 1-12 months of age, possible fluoride ingestion per kg body mass was estimated. None of the formulae, if reconstituted using water containing up to 0.1 ppm F, should provide a daily fluoride intake above the suggested threshold for fluorosis of 0.1 mg F/kg body mass. However, if reconstituted with water containing 1.0 ppm F they should all provide a daily fluoride intake of above the suggested threshold for fluorosis with intakes up to 2-3 times the recommended upper 'optimal' limit of 0.07 mg/kg body mass. Under these conditions the water used to reconstitute the formulae would provide 65-97 percent of the fluoride ingested. These figures are likely to be overestimates due to the intake of nutrients from other sources reducing formulae consumption and also due to the lower

  2. Salivary Fluoride Levels after Use of High-Fluoride Dentifrice

    PubMed Central

    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. PMID:25821849

  3. 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.

  4. Fluoride intake from fluids and urinary fluoride excretion by young children in Kuwait: a non-fluoridated community.

    PubMed

    Akpata, Enosakhare S; Behbehani, Jawad; Akbar, Jaber; Thalib, Lukman; Mojiminiyi, Olusegun

    2014-06-01

    To determine the pattern of fluid consumption, fluoride intake from the fluids and urinary fluoride excretion by children aged 1-9 years in Kuwait, a nonfluoridated community. Using the cluster sampling technique, children aged 1-9 years were chosen from 2000 randomly selected households in Kuwait. Questionnaires were then administered to their mothers to determine the children's daily fluid intake. Fluoride concentrations in tap water as well as all brands of bottled water and beverages consumed by the children were measured, using the fluoride ion-specific electrode. Fluoride excretion was determined in 400 randomly selected children, based on fluoride/creatinine ratio. The mean daily fluid consumption by the children was high, being 1115-1545 ml. About 40% of the fluid intake was plain (tap and bottled) water and approximately 10% of the children drank bottled water exclusively. Fluoride concentration in tap water was low (0.04±SD 0.02 ppm), but was higher in bottled water (0.28±SD 0.40 ppm). Mean daily fluoride ingestion from fluids was 0.013-0.018 mg/kg body weight (bw). Even after allowing for fluoride ingestion from other sources, mean daily fluoride ingestion was still below 0.1 mg/kg bw set by the United States of America Institute of Medicine as the lowest-observed-adverse-effect level for moderate enamel fluorosis in children aged up to 8 years. Furthermore, the mean daily urinary fluoride excretion of 128-220 μg was below the provisional standard of 360-480 μg for optimal fluoride usage by children aged 3-5 years. Fluoride ingestion from fluids and urinary fluoride excretion by the children were below the recommendations for optimal fluoride usage. Thus, there is room for an upward adjustment of fluoride level in public drinking water supplies in Kuwait, as a caries preventive measure. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Debating Water Fluoridation Before Dr. Strangelove.

    PubMed

    Carstairs, Catherine

    2015-08-01

    In the 1930s, scientists learned that small amounts of fluoride naturally occurring in water could protect teeth from decay, and the idea of artificially adding fluoride to public water supplies to achieve the same effect arose. In the 1940s and early 1950s, a number of studies were completed to determine whether fluoride could have harmful effects. The research suggested that the possibility of harm was small. In the early 1950s, Canadian and US medical, dental, and public health bodies all endorsed water fluoridation. I argue in this article that some early concerns about the toxicity of fluoride were put aside as evidence regarding the effectiveness and safety of water fluoridation mounted and as the opposition was taken over by people with little standing in the scientific, medical, and dental communities. The sense of optimism that infused postwar science and the desire of dentists to have a magic bullet that could wipe out tooth decay also affected the scientific debate.

  6. 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.

  7. Aluminum fluoride interactions with troponin C.

    PubMed Central

    Phan, B C; Reisler, E

    1993-01-01

    The increasing interest in the metal ion aluminum fluoride and beryllium fluoride complexes as phosphate analogs in the myosin ATPase reaction and in muscle fiber studies prompted the examination of their interactions with the regulatory system of troponin and tropomyosin. In this work, the effects of these metal ion analogs on the spectral properties of the Ca(2+)-binding subunit of troponin, troponin C (TnC), were examined. In contrast to beryllium fluoride which did not change the spectral properties of TnC, aluminum fluoride binding induced an increase in both the alpha-helicity and the tyrosine fluorescence of TnC and exposed a hydrophobic region on this protein for fluorescent probe binding. Aluminum fluoride also reduced the Ca2+ and/or Mg(2+)-induced changes on TnC. These results indicate a direct interaction of aluminum fluoride with TnC and merit consideration in designing muscle fiber experiments with this phosphate analog. PMID:8312488

  8. Silver diamine fluoride: a caries "silver-fluoride bullet".

    PubMed

    Rosenblatt, A; Stamford, T C M; Niederman, R

    2009-02-01

    The antimicrobial use of silver compounds pivots on the 100-year-old application of silver nitrate, silver foil, and silver sutures for the prevention and treatment of ocular, surgical, and dental infections. Ag(+) kills pathogenic organisms at concentrations of <50 ppm, and current/potential anti-infective applications include: acute burn coverings, catheter linings, water purification systems, hospital gowns, and caries prevention. To distill the current best evidence relative to caries, this systematic review asked: Will silver diamine fluoride (SDF) more effectively prevent caries than fluoride varnish? A five-database search, reference review, and hand search identified 99 human clinical trials in three languages published between 1966 and 2006. Dual review for controlled clinical trials with the patient as the unit of observation, and excluding cross-sectional, animal, in vitro studies, and opinions, identified 2 studies meeting the inclusion criteria. The trials indicated that SDF's lowest prevented fractions for caries arrest and caries prevention were 96.1% and 70.3%, respectively. In contrast, fluoride varnish's highest prevented fractions for caries arrest and caries prevention were 21.3% and 55.7%, respectively. Similarly, SDF's highest numbers needed to treat for caries arrest and caries prevention were 0.8 (95% CI=0.5-1.0) and 0.9 (95% CI=0.4-1.1), respectively. For fluoride varnish, the lowest numbers needed to treat for caries arrest and prevention were 3.7 (95% CI=3.4-3.9) and 1.1 (95% CI=0.7-1.4), respectively. Adverse events were monitored, with no significant differences between control and experimental groups. These promising results suggest that SDF is more effective than fluoride varnish, and may be a valuable caries-preventive intervention. As well, the availability of a safe, effective, efficient, and equitable caries-preventive agent appears to meet the criteria of both the WHO Millennium Goals and the US Institute of Medicine's criteria

  9. 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.

  10. 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.

  11. Magnesium Fluoride Reduction Vessel Liners

    DTIC Science & Technology

    1986-03-26

    Carolina Metals, the fluoride is reduced to power by means of a Mikro #2 hemmer mill (Figure 5). The material is then separated into the different...The jolter table previously referred to in the liner pro - ceasing operation, is the knockout station. As shown in Figure 36, the vessel is inverted...was much more extensive than normally performed to establish the quality of thý metal pro - duced using the MgF2 liners. There are no indications of

  12. Fluoride Glass Fiber Sources: Problems and Prospects

    DTIC Science & Technology

    2010-09-01

    Fluoride glass fiber sources: Problems and prospects Marcel Poulain and Gwenael Mazé Rennes University and Le V erre Fluoré Report Documentation Page...A 3. DATES COVERED - 4. TITLE AND SUBTITLE Fluoride glass fiber sources:Problems and prospects 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...Introduction 2 Fluoride glass technology 3 Specifications of active fibers 4 Achievements 5 Problems and prospects 6 Conclusion INTRODUCTION The

  13. 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.

  14. Plaque and saliva fluoride levels after placement of fluoride releasing pit and fissure sealants.

    PubMed

    Rajtboriraks, Daranee; Nakornchai, Siriruk; Bunditsing, Panit; Surarit, Rudee; Iemjarern, Piyarat

    2004-01-01

    The objectives of this study were to investigate the fluoride levels in plaque and saliva before and after applying fluoride-containing pit and fissure sealants, and compare the fluoride release of 2 types of sealants at the different time intervals. Eighteen children ages 6 to 9 years were randomly divided into 2 groups: Group 1--sealant containing fluorosilicate glass (Helioseal-F); and group 2--sealant containing methacryloyl fluoride-methyl methacrylate copolymer (Teethmate-F). Saliva and plaque samples were collected before and after the sealants were placed on their 4 first permanent molars. Fluoride levels were determined using the microdiffusion method. Fluoride concentrations before and after placing the sealants were analyzed by paired t test, and the fluoride concentrations between the 2 sealants were compared by t test, with the level of significance at 0.05. There was no significant difference between salivary fluoride levels before and after sealant placement application in both groups. The plaque fluoride level of Helioseal-F group at 24 hours was significantly higher than the baseline level (P = .03), and was not different afterwards. The plaque fluoride levels after sealant with Teethmate-F were not significantly different when compared to the baseline. However, there were no significant differences between salivary and plaque fluoride levels of the 2 groups at different time intervals. The groups sealed with sealant containing fluorosilicate glass showed significant increase of plaque fluoride level only at 24 hours after sealant placement.

  15. 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.

  16. 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
    % ...

  17. 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
    % ...

  18. Complete Sensitivity/Uncertainty Analysis of LR-0 Reactor Experiments with MSRE FLiBe Salt and Perform Comparison with Molten Salt Cooled and Molten Salt Fueled Reactor Models

    SciTech Connect

    Brown, Nicholas R.; Powers, Jeffrey J.; Mueller, Don; Patton, Bruce W.

    2016-12-01

    In September 2016, reactor physics measurements were conducted at Research Centre Rez (RC Rez) using the FLiBe (2 7LiF + BeF2) salt from the Molten Salt Reactor Experiment (MSRE) in the LR-0 low power nuclear reactor. These experiments were intended to inform on neutron spectral effects and nuclear data uncertainties for advanced reactor systems using FLiBe salt in a thermal neutron energy spectrum. Oak Ridge National Laboratory (ORNL), in collaboration with RC Rez, performed sensitivity/uncertainty (S/U) analyses of these experiments as part of the ongoing collaboration between the United States and the Czech Republic on civilian nuclear energy research and development. The objectives of these analyses were (1) to identify potential sources of bias in fluoride salt-cooled and salt-fueled reactor simulations resulting from cross section uncertainties, and (2) to produce the sensitivity of neutron multiplication to cross section data on an energy-dependent basis for specific nuclides. This report provides a final report on the S/U analyses of critical experiments at the LR-0 Reactor relevant to fluoride salt-cooled high temperature reactor (FHR) and liquid-fueled molten salt reactor (MSR) concepts. In the future, these S/U analyses could be used to inform the design of additional FLiBe-based experiments using the salt from MSRE. The key finding of this work is that, for both solid and liquid fueled fluoride salt reactors, radiative capture in 7Li is the most significant contributor to potential bias in neutronics calculations within the FLiBe salt.

  19. Fluoride assay methodology for carbonated beverages.

    PubMed

    Heilman, Judith R; Levy, Steven M; Wefel, James S; Patterson, Kristine Y; Cutrufelli, Rena; Pehrsson, Pamela R; Holden, Joanne M

    2006-01-01

    The purpose of this paper was to review different methodological techniques used for the assessment of fluoride in carbonated beverages, and compare results using a fluoride ion electrode direct read method with and without a prior decarbonation treatment. The carbonated beverages in this study were either purchased locally at grocery stores in Iowa City, Iowa, or purchased as part of a national representative sampling approach included in the National Fluoride Database and Intake Assessment Study (NFDIAS). The samples were compared with and without a decarbonating process. Soda pop and beer samples were analyzed by removing a 1-ml sample and adding a 1-ml buffer solution. The fluoride concentration of the sample and buffer combination was then determined using a fluoride ion specific electrode. There was no significant difference in the fluoride concentration of the samples with or without prior decarbonation. The mean absolute difference between the soda pop group with and without decarbonation was 0.01 ppm F, while results from the beer samples showed variation of 0.00 to 0.02 parts per million fluoride (ppm F). These differences were not statistically significant for the soda pop or beer groups (P=.50 and P=.74, respectively). Whether or not decarbonation was conducted prior to analysis, the fluoride assay results were the same. Therefore, decarbonation of soda pop and beer was deemed unnecessary prior to fluoride analysis.

  20. 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.

  1. High fluoride exposure in hemodialysis patients.

    PubMed

    Bello, V A; Gitelman, H J

    1990-04-01

    The observation of higher plasma flouride levels in our hemodialysis (HD) patients than our continuous ambulatory peritoneal dialysis (CAPD) patients (4.0 +/- 0.5 mumol/L [n = 17] v 2.5 +/- 0.3 mumol/L [n = 17], P less than 0.005) prompted an evaluation of fluoride metabolism during HD. We found that serum fluoride was completely ultrafiltrable across cuprophane membranes (99% +/- 4%) and that HD produced acute changes in plasma fluoride levels that correlated well with the fluoride gradient between plasma and dialysis fluid at the start of dialysis. Our HD fluids contained significantly higher fluoride concentrations than were present in commercially prepared peritoneal dialysis fluid. Our fluids are prepared from fluoridated tap water that is purified by reverse osmosis (RO). We conclude that the different concentrations of fluoride in our dialysis fluids account for the differences in the plasma flouride concentrations between our dialysis groups. Since many HD units rely on RO systems to purify fluoridated tap water, it is likely that many HD patients are being exposed inadvertently to increased concentrations of fluoride.

  2. Preparation of an experimental low-fluoride diet from single-cell organisms for rats and mice.

    PubMed

    Khalawan, S A; Elliott, J C; Fearnhead, R W

    1980-11-01

    1. A method for producing a standard low-fluoride diet from a green alga and yeast is described. Chlorella pyrenoidosa was grown in a culture medium prepared with distilled water and analytical grade chemical salts. The spent culture medium from the alga culture was reclaimed and replenished with salts and sucrose for the production of yeast, Saccharomyces cerevisiae. 2. The single-cell organisms were separated by centrifugation from their culture media and the dried cells were blended with sucrose, maize oil, cellulose and a salt mix to produce diet pellets for rats and mice. 3. The diet was readily accepted as food by rats and mice and it was found to contain 100-300 micrograms fluoride/kg dry weight. Two generations of rats and four generations of mice were bred on this diet. 4. The use of hydroxyapatite to reduce the fluoride content of the chemical used in the production of the alga and yeast biomass was investigated. Diet pellets prepared with this biomass contained 45-60 micrograms fluoride/kg dry weight.

  3. URINARY FLUORIDE OUTPUT IN CHILDREN FOLLOWING THE USE OF A DUAL-FLUORIDE VARNISH FORMULATION

    PubMed Central

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

    2009-01-01

    Objective: This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to Duraphat™. Material and methods: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM™). After 1-month interval (phase II), the same amount (0.2 mL) of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, Colgate™) was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (p<0.05). Results: There were significant differences in the urinary fluoride output between phases I and II. The use of Duofluorid XII did not significantly increase the urinary fluoride output, when compared to baseline levels. The application of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. Conclusions: The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe. PMID:19466247

  4. 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.

  5. Inventories and mobilization of unsaturated zone sulfate, fluoride, and chloride related to land use change in semiarid regions, southwestern United States and Australia

    USGS Publications Warehouse

    Scanlon, B.R.; Stonestrom, D.A.; Reedy, R.C.; Leaney, F.W.; Gates, J.; Cresswell, R.G.

    2009-01-01

    Unsaturated zone salt reservoirs are potentially mobilized by increased groundwater recharge as semiarid lands are cultivated. This study explores the amounts of pore water sulfate and fluoride relative to chloride in unsaturated zone profiles, evaluates their sources, estimates mobilization due to past land use change, and assesses the impacts on groundwater quality. Inventories of water-extractable chloride, sulfate, and fluoride were determined from borehole samples of soils and sediments collected beneath natural ecosystems (N = 4), nonirrigated ("rain-fed") croplands (N = 18), and irrigated croplands (N = 6) in the southwestern United States and in the Murray Basin, Australia. Natural ecosystems contain generally large sulfate inventories (7800-120,000 kg/ha) and lower fluoride inventories (630-3900 kg/ha) relative to chloride inventories (6600-41,000 kg/ha). Order-of-magnitude higher chloride concentrations in precipitation and generally longer accumulation times result in much larger chloride inventories in the Murray Basin than in the southwestern United States. Atmospheric deposition during the current dry interglacial climatic regime accounts for most of the measured sulfate in both U.S. and Australian regions. Fluoride inventories are greater than can be accounted for by atmospheric deposition in most cases, suggesting that fluoride may accumulate across glacial/ interglacial climatic cycles. Chemical modeling indicates that fluorite controls fluoride mobility and suggests that water-extractable fluoride may include some fluoride from mineral dissolution. Increased groundwater drainage/recharge following land use change readily mobilized chloride. Sulfate displacement fronts matched or lagged chloride fronts by up to 4 m. In contrast, fluoride mobilization was minimal in all regions. Understanding linkages between salt inventories, increased recharge, and groundwater quality is important for quantifying impacts of anthropogenic activities on groundwater

  6. Inventories and mobilization of unsaturated zone sulfate, fluoride, and chloride related to land use change in semiarid regions, southwestern United States and Australia

    NASA Astrophysics Data System (ADS)

    Scanlon, Bridget R.; Stonestrom, David A.; Reedy, Robert C.; Leaney, Fred W.; Gates, John; Cresswell, Richard G.

    2009-07-01

    Unsaturated zone salt reservoirs are potentially mobilized by increased groundwater recharge as semiarid lands are cultivated. This study explores the amounts of pore water sulfate and fluoride relative to chloride in unsaturated zone profiles, evaluates their sources, estimates mobilization due to past land use change, and assesses the impacts on groundwater quality. Inventories of water-extractable chloride, sulfate, and fluoride were determined from borehole samples of soils and sediments collected beneath natural ecosystems (N = 4), nonirrigated ("rain-fed") croplands (N = 18), and irrigated croplands (N = 6) in the southwestern United States and in the Murray Basin, Australia. Natural ecosystems contain generally large sulfate inventories (7800-120,000 kg/ha) and lower fluoride inventories (630-3900 kg/ha) relative to chloride inventories (6600-41,000 kg/ha). Order-of-magnitude higher chloride concentrations in precipitation and generally longer accumulation times result in much larger chloride inventories in the Murray Basin than in the southwestern United States. Atmospheric deposition during the current dry interglacial climatic regime accounts for most of the measured sulfate in both U.S. and Australian regions. Fluoride inventories are greater than can be accounted for by atmospheric deposition in most cases, suggesting that fluoride may accumulate across glacial/interglacial climatic cycles. Chemical modeling indicates that fluorite controls fluoride mobility and suggests that water-extractable fluoride may include some fluoride from mineral dissolution. Increased groundwater drainage/recharge following land use change readily mobilized chloride. Sulfate displacement fronts matched or lagged chloride fronts by up to 4 m. In contrast, fluoride mobilization was minimal in all regions. Understanding linkages between salt inventories, increased recharge, and groundwater quality is important for quantifying impacts of anthropogenic activities on groundwater

  7. [Influence of natural fluoride concentration in drinking water on dental health of first class pupils in an area with enhanced fluoride content at the beginning of the 21st century].

    PubMed

    Steinmeyer, R

    2011-08-01

    Since the end of the first half of the 20 (th) century it is well-known that fluoride concentrations in drinking water of about 1 ppm reduce the prevalence of dental caries by about 40-60%. This knowledge led to the fluoridation of drinking water during the second half of the 20 (th) century in many countries, including East Germany. Although the natural F (-) content in drinking water in Germany is usually very low, the eastern Eifel is one of the few larger areas in Germany with (nearly) optimal (0.7-1.0 ppm) or moderately enhanced (0.3-0.7 ppm) natural fluoride concentrations in drinking water. 30 years ago, in 1977, the caries prevalence of children of various age groups in the fluoride-rich areas of the eastern Eifel was established by Einwag to be about 40% lower than in adjacent fluoride-poor regions (0.1 ppm). Meanwhile fluoride has become available from many different sources for children of any age: e. g., toothpaste (with 500 ppm fluoride even for very young children who just got the first tooth), fluoridated salt, professional fluoride applications (paid by health insurances), the rising consumption of mineral waters (many of which have a fluoride content >0.3 ppm). This poses the question of the current influence of enhanced natural drinking water fluoride concentrations on caries prevalence in children. The results of the dental examinations of 9 555 pupils (6 or 7 years old) of the first classes of all 63 primary schools in the Landkreis Mayen-Koblenz from 5 years (2004/2005-2008/2009) are compared to the fluoride content of the drinking water. The data show no obvious correlation between dental health and fluoride concentration for any of the dental health parameters investigated. However, in spite of the low geographic resolution of social parameters, there was a notable connection between dental health status and sociodemographic indicators for the respective region. 30 years after the study by Einwag in the same region, the

  8. Fluorescent Sensing of Fluoride in Cellular System

    PubMed Central

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

    2015-01-01

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

  9. 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

  10. Fluoride in drinking water and dental fluorosis.

    PubMed

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

    2010-08-01

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

  11. 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

  12. Fluoride Concentration in Dentin of Exfoliated Primary Teeth as a Biomarker for Cumulative Fluoride Exposure

    PubMed Central

    dela Cruz, G.G.; Rozier, R.G.; Bawden, J.W.

    2008-01-01

    A biomarker for lifetime fluoride exposure would facilitate population-based research and policy making but currently does not exist. This study examined the suitability of primary tooth dentin as a biomarker by comparing dentin fluoride concentration and fluoride exposures. Ninety-nine children's exfoliated primary teeth were collected from 2 fluoridated and 2 fluoride-deficient communities in North Carolina. Coronal dentin was isolated by microdissection and fluoride concentration assayed using the microdiffusion, ion-specific electrode technique. Information on children's fluoride exposures since birth from drinking water, toothpaste, supplements, rinses, food and beverages was collected by a self-reported questionnaire administered to caregivers. Only a small portion of the variance (10%) in incisor dentin fluoride (mean 792, SD 402 mg/kg) was accounted for by the best linear regression model as evaluated by the adjusted R2. A moderate portion of the variance (60%) of molar dentin fluoride (mean 768, SD 489 mg/kg) was predicted by dietary fluoride supplement exposures, community of residence, and frequent tea consumption. Results for molars suggest that primary tooth dentin concentration may prove to be a satisfactory biomarker for fluoride exposure. PMID:18832828

  13. 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.

  14. An in vitro assessment of fluoride uptake by tooth enamel from four different fluoride dentifrices.

    PubMed

    Patil, V H; Anegundi, R T

    2014-10-01

    The aim of this study was to evaluate fluoride uptake by tooth enamel with four different fluoride dentifrices. Sixty human premolars extracted for orthodontic purpose were selected for the study. The teeth were covered with nail varnish leaving a window of 4 × 4 mm on the enamel surface of the buccal and lingual sides. The teeth were demineralised and were divided into four groups with 15 teeth in each group. The buccal window served as experimental and the lingual as control. The teeth were immersed in toothpaste slurry containing: sodium fluoride (Group A); sodium monofluorophosphate (Group B); stannous fluoride (Group C) and amine fluoride (Group D). The fluoride content in the etched superficial enamel layer in the windows was analysed using a fluoride ion-specific electrode. Within the parameters of this study, the uptake of fluoride was statistically significant in Group D (p < 0.05). The uptake of fluoride by tooth enamel in an increasing order was Group A < Group B < Group C < Group D. The study showed that enamel treated with amine fluoride had the highest fluoride uptake.

  15. 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.

  16. 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.

  17. Environmental evaluation of fluoride in drinking water at "Los Altos de Jalisco," in the central Mexico region.

    PubMed

    Hurtado, Roberto; Gardea-Torresdey, Jorge

    Naturally occurring fluoride has been detected and quantified in drinking water in several cities of the "Los Altos de Jalisco" (LAJ) region. LAJ is located in the northeastern part of the state of Jalisco-Mexico, covering an area of 16,410 km2 with a population of 696,318 in 20 municipalities. Drinking water comes mainly from groundwater aquifers, located in the Trans-Mexican Volcanic Belt, which is a volcanic region characterized by hydrothermal activity. Results indicated that water supply from 42% of the municipalities had a fluoride concentration over the Mexican standards of 1.5 mg/L. It is important to notice that there are three cities, Lagos de Moreno (1.66-5.88 mg/L F(-)), Teocaltiche (3.82-18.58 mg/L F(-)), and Encarnación de Díaz (2.58-4.40 mg/L F(-)) where all water samples resulted in fluoride concentration over the maximum contaminant level. The total population from these three cities is over 122,000 inhabitants. Another important city with high levels of fluoride in the water supply was Tepatitlán de Morelos (2 wells with 6.54 and 13.47 mg/L F(-)). In addition to water supply, 30 samples of brand-name bottled water were tested. Surprisingly, 8 samples (27%) demonstrated fluoride level over the standards, mainly Agua de Lagos with 5.27 mg/L. Fluoridated table salt (200-300 mg/kg F(-)) is another important source of fluoride. A large number of people living in the region, mainly school children, might be under adverse health risk because they are consuming contaminated drinking water. It is well known that long-term exposure to water with high levels of fluoride produces severe health problems.

  18. Tritium control and capture in salt-cooled fission and fusion reactors: Status, challenges, and path forward

    DOE PAGES

    Forsberg, Charles W.; Lam, Stephen; Carpenter, David M.; ...

    2017-01-24

    Three advanced nuclear power systems use liquid salt coolants that generate tritium and thus face the common challenges of containing and capturing tritium to prevent its release to the environment. The Fluoride-salt-cooled High-temperature Reactor (FHR) uses clean fluoride salt coolants and the same graphite-matrix coated-particle fuel as high-temperature gas-cooled reactors. Molten salt reactors (MSRs) dissolve the fuel in a fluoride or chloride salt with release of fission product tritium into the salt. In most FHR and MSR systems, the base-line salts contain lithium where isotopically separated 7Li is proposed to minimize tritium production from neutron interactions with the salt. Themore » Chinese Academy of Science plans to start operation of a 2-MWt molten salt test reactor by 2020. For high-magnetic-field fusion machines, the use of lithium enriched in 6Li is proposed to maximize tritium generation the fuel for a fusion machine. Advances in superconductors that enable higher power densities may require the use of molten lithium salts for fusion blankets and as coolants. Recent technical advances in these three reactor classes have resulted in increased government and private interest and the beginning of a coordinated effort to address the tritium control challenges in 700 °C liquid salt systems. We describe characteristics of salt-cooled fission and fusion machines, the basis for growing interest in these technologies, tritium generation in molten salts, the environment for tritium capture, models for high-temperature tritium transport in salt systems, alternative strategies for tritium control, and ongoing experimental work. Several methods to control tritium appear viable. Finally, limited experimental data is the primary constraint for designing efficient cost-effective methods of tritium control.« less

  19. 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

  20. Welsh water should reinstate fluoridation on Anglesey.

    PubMed

    Hulse, G; Kenrick, A; Thomas, C H; Thomas, A; Davies, D J; Lennon, M A

    1995-01-21

    In 1992, Welsh Water withdrew the successful water fluoridation scheme on Anglesey. Despite evidence of the benefits of water fluoridation and the rise in number of children with tooth decay since the scheme's withdrawal, Welsh Water is still not prepared to re-establish the scheme.

  1. Potentiometric Determination of Fluoride Concentration in Beers.

    PubMed

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

    2017-04-26

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

  2. 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.

  3. 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.

  4. 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.

  5. 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. Copyright © 2015. Published by Elsevier Inc.

  6. 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.

  7. Combinatorial incorporation of fluoride and cobalt ions into calcium phosphates to stimulate osteogenesis and angiogenesis.

    PubMed

    Birgani, Zeinab Tahmasebi; Gharraee, Nazli; Malhotra, Angad; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-02-29

    Bone healing requires two critical mechanisms, angiogenesis and osteogenesis. In order to improve bone graft substitutes, both mechanisms should be addressed simultaneously. While the individual effects of various bioinorganics have been studied, an understanding of the combinatorial effects is lacking. Cobalt and fluoride ions, in appropriate concentrations, are known to individually favor the vascularization and mineralization processes, respectively. This study investigated the potential of using a combination of fluoride and cobalt ions to simultaneously promote osteogenesis and angiogenesis in human mesenchymal stromal cells (hMSCs). Using a two-step biomimetic method, wells of tissue culture plates were coated with a calcium phosphate (CaP) layer without or with the incorporation of cobalt, fluoride, or both. In parallel, hMSCs were cultured on uncoated well plates, and cultured with cobalt and/or fluoride ions within the media. The results revealed that cobalt ions increased the expression of angiogenic markers, with the effects being stronger when the ions were added as a dissolved salt in cell medium as compared to incorporation into CaP. Cobalt ions generally suppressed the ALP activity, the expression of osteogenic genes, and the level of mineralization, regardless of delivery method. Fluoride ions, individually or in combination with cobalt, significantly increased the expression of many of the selected osteogenic markers, as well as mineral deposition. This study demonstrates an approach to simultaneously target the two essential mechanisms in bone healing: angiogenesis and osteogenesis. The incorporation of cobalt and fluoride into CaPs is a promising method to improve the biological performance of fully synthetic bone graft substitutes.

  8. Manufacture and properties of fluoride cement

    NASA Astrophysics Data System (ADS)

    Malata-Chirwa, Charles David

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

  9. Discovery of Interstellar Hydrogen Fluoride

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  10. 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.

  11. 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.

  12. 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.

  13. Differential Toxicities of Nickel Salts to the Nematode Caenorhabditis elegans.

    PubMed

    Meyer, Dean; Birdsey, Jennifer M; Wendolowski, Mark A; Dobbin, Kevin K; Williams, Phillip L

    2016-08-01

    This study focused on assessing whether nickel (Ni) toxicity to the nematode Caenorhabditis elegans was affected by the molecular structure of the Ni salt used. Nematodes were exposed to seven Ni salts [Ni sulfate hexahydrate (NiSO4·6H2O), Ni chloride hexahydrate (NiCl2·6H2O), Ni acetate tetrahydrate (Ni(OCOCH3)2·4H2O), Ni nitrate hexahydrate (N2NiO6·6H2O), anhydrous Ni iodide (NiI2), Ni sulfamate hydrate (Ni(SO3NH2)2·H2O), and Ni fluoride tetrahydrate (NiF2·4H2O)] in an aquatic medium for 24 h, and lethality curves were generated and analyzed. Ni fluoride, Ni iodide, and Ni chloride were most toxic to C. elegans, followed by Ni nitrate, Ni sulfamate, Ni acetate, and Ni sulfate. The LC50 values of the halogen-containing salts were statistically different from the corresponding value of the least toxic salt, Ni sulfate. This finding is consistent with the expected high bioavailability of free Ni ions in halide solutions. We recommend that the halide salts be used in future Ni testing involving aquatic invertebrates.

  14. Recent advancements in fluoride: A systematic review

    PubMed Central

    Bansal, Ankita; Ingle, Navin Anand; Kaur, Navpreet; Ingle, Ekta

    2015-01-01

    To review advancements of fluoride in dentistry, a search of 21 electronic databases and World Wide Web was conducted. Relevant journals were hand searched and further information was requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Fluoride has become an important tool in preventive dentistry. Current research is focused on the development of strategies to improve fluoride efficacy. Fluoride therapy in the form of varnish, gel, mouth rinse, or toothpaste has been used extensively as a caries-preventive intervention for over three decades. The purpose of this review is to inform the reader about new research related to the use of fluoride for the prevention of dental caries. PMID:26539383

  15. An assessment of bone fluoride and osteosarcoma.

    PubMed

    Kim, F M; Hayes, C; Williams, P L; Whitford, G M; Joshipura, K J; Hoover, R N; Douglass, C W

    2011-10-01

    The association between fluoride and risk for osteosarcoma is controversial. The purpose of this study was to determine if bone fluoride levels are higher in individuals with osteosarcoma. Incident cases of osteosarcoma (N = 137) and tumor controls (N = 51) were identified by orthopedic physicians, and segments of tumor-adjacent bone and iliac crest bone were analyzed for fluoride content. Logistic regression adjusted for age and sex and potential confounders of osteosarcoma was used to estimate odds ratios (OR) and 95% confidence intervals (CI). There was no significant difference in bone fluoride levels between cases and controls. The OR adjusted for age, gender, and a history of broken bones was 1.33 (95% CI: 0.56-3.15). No significant association between bone fluoride levels and osteosarcoma risk was detected in our case-control study, based on controls with other tumor diagnoses.

  16. Corrosion behavior of zirconia in acidulated phosphate fluoride

    PubMed Central

    Thomas, Anie; Sridhar, Sathyanarayanan; Aghyarian, Shant; Watkins-curry, Pilanda; Chan, Julia Y.; Pozzi, Alessandro; Rodrigues, Danieli C.

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media. Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study. PMID:27008257

  17. Prediction of the thermophysical properties of molten salt fast reactor fuel from first-principles

    NASA Astrophysics Data System (ADS)

    Gheribi, A. E.; Corradini, D.; Dewan, L.; Chartrand, P.; Simon, C.; Madden, P. A.; Salanne, M.

    2014-05-01

    Molten fluorides are known to show favourable thermophysical properties which make them good candidate coolants for nuclear fission reactors. Here we investigate the special case of mixtures of lithium fluoride and thorium fluoride, which act both as coolant and as fuel in the molten salt fast reactor concept. By using ab initio parameterised polarisable force fields, we show that it is possible to calculate the whole set of properties (density, thermal expansion, heat capacity, viscosity and thermal conductivity) which are necessary for assessing the heat transfer performance of the melt over the whole range of compositions and temperatures. We then deduce from our calculations several figures of merit which are important in helping the optimisation of the design of molten salt fast reactors.

  18. Thermal-hydraulics of internally heated molten salts and application to the Molten Salt Fast Reactor

    NASA Astrophysics Data System (ADS)

    Fiorina, Carlo; Cammi, Antonio; Luzzi, Lelio; Mikityuk, Konstantin; Ninokata, Hisashi; Ricotti, Marco E.

    2014-04-01

    The Molten Salt Reactors (MSR) are an innovative kind of nuclear reactors and are presently considered in the framework of the Generation IV International Forum (GIF-IV) for their promising performances in terms of low resource utilization, waste minimization and enhanced safety. A unique feature of MSRs is that molten fluoride salts play the distinctive role of both fuel (heat source) and coolant. The presence of an internal heat generation perturbs the temperature field and consequences are to be expected on the heat transfer characteristics of the molten salts. In this paper, the problem of heat transfer for internally heated fluids in a straight circular channel is first faced on a theoretical ground. The effect of internal heat generation is demonstrated to be described by a corrective factor applied to traditional correlations for the Nusselt number. It is shown that the corrective factor can be fully characterized by making explicit the dependency on Reynolds and Prandtl numbers. On this basis, a preliminary correlation is proposed for the case of molten fluoride salts by interpolating the results provided by an analytic approach previously developed at the Politecnico di Milano. The experimental facility and the related measuring procedure for testing the proposed correlation are then presented. Finally, the developed correlation is used to carry out a parametric investigation on the effect of internal heat generation on the main out-of-core components of the Molten Salt Fast Reactor (MSFR), the reference circulating-fuel MSR design in the GIF-IV. The volumetric power determines higher temperatures at the channel wall, but the effect is significant only in case of large diameters and/or low velocities.

  19. 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.

  20. Dental fluorosis in children exposed to multiple sources of fluoride: implications for school fluoridation programs.

    PubMed Central

    Rozier, R G; Dudney, G G

    1981-01-01

    Naturally occurring fluorides of varying levels made possible a study do determine if continuous, lifetime use of home drinking water fluoridated to optimum levels combined with the use of school fluoridated water beginning at school age causes objectionable levels of dental fluorosis as defined by Dr. H. Trendley Dean in 1936. Examinations were performed on 120 children who had fluoride concentrations in home well water ranging from 0.1 to 6.5 ppm and attended a school with a private water source containing 4.5 ppm natural fluoride (5.6 times the optimum for community fluoridation in the area). Fluorosis scores were calculated for each of four groups formed according to fluoride concentrations in home water supplies. The group with an average concentration of 0.87 ppm was found to have a Community Index of Dental Fluorosis well within Dean's normal limits. The results suggest that children consuming water at home containing the optimal fluoride concentration and drinking water at school containing the recommended fluoride level (4.5 times the optimum) are not at risk to dental fluorosis that impairs appearance. If this finding is corroborated by future clinical studies, the target population for school fluoridation can be expanded and the administration of these programs facilitated. PMID:7302108

  1. The Determination of Atmospheric Fluoride with a Specific Ion Electrode

    NASA Technical Reports Server (NTRS)

    Feldstein, M.; Levaggi, D. A.

    1971-01-01

    Atmospheric fluoride is collected on lime-coated filter paper exposed to the ambient atmosphere for 30-day periods. The fluoride is eluted from the paper and analyzed with the use of a fluoride specific ion electrode. The technique permits evaluation of potential fluoride sources in terms of downwind concentrations and provides a simple, rapid procedure for the analysis of large numbers of samples.

  2. 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)

  3. 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,…

  4. 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 to...

  5. 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 to...

  6. 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 to...

  7. 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)

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

    PubMed

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

    2017-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1985-05-01

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

  10. Tritium Control and Capture in Salt-Cooled Fission and Fusion Reactors: Status, Challenges, and Path Forward

    DOE PAGES

    Forsberg, Charles W.; Lam, Stephen; Carpenter, David M.; ...

    2017-02-26

    Three advanced nuclear power systems use liquid salt coolants that generate tritium and thus face the common challenges of containing and capturing tritium to prevent its release to the environment. The fluoride salt–cooled high-temperature reactor (FHR) uses clean fluoride salt coolants and the same graphite-matrix coated-particle fuel as high-temperature gas-cooled reactors. Molten salt reactors (MSRs) dissolve the fuel in a fluoride or chloride salt with release of fission product tritium into the salt. In most FHR and MSR systems, the baseline salts contain lithium where isotopically separated 7Li is proposed to minimize tritium production from neutron interactions with the salt.more » The Chinese Academy of Sciences plans to start operation of a 2-MW(thermal) molten salt test reactor by 2020. For high-magnetic-field fusion machines, the use of lithium enriched in 6Li is proposed to maximize tritium generation—the fuel for a fusion machine. Advances in superconductors that enable higher power densities may require the use of molten lithium salts for fusion blankets and as coolants. Recent technical advances in these three reactor classes have resulted in increased government and private interest and the beginning of a coordinated effort to address the tritium control challenges in 700°C liquid salt systems. In this paper, we describe characteristics of salt-cooled fission and fusion machines, the basis for growing interest in these technologies, tritium generation in molten salts, the environment for tritium capture, models for high-temperature tritium transport in salt systems, alternative strategies for tritium control, and ongoing experimental work. Several methods to control tritium appear viable. Finally, limited experimental data are the primary constraint for designing efficient cost-effective methods of tritium control.« less

  11. Tritium Control and Capture in Salt-Cooled Fission and Fusion Reactors: Status, Challenges, and Path Forward

    DOE PAGES

    Forsberg, Charles W.; Lam, Stephen; Carpenter, David M.; ...

    2017-02-26

    Three advanced nuclear power systems use liquid salt coolants that generate tritium and thus face the common challenges of containing and capturing tritium to prevent its release to the environment. The fluoride salt–cooled high-temperature reactor (FHR) uses clean fluoride salt coolants and the same graphite-matrix coated-particle fuel as high-temperature gas-cooled reactors. Molten salt reactors (MSRs) dissolve the fuel in a fluoride or chloride salt with release of fission product tritium into the salt. In most FHR and MSR systems, the baseline salts contain lithium where isotopically separated 7Li is proposed to minimize tritium production from neutron interactions with the salt.more » The Chinese Academy of Sciences plans to start operation of a 2-MW(thermal) molten salt test reactor by 2020. For high-magnetic-field fusion machines, the use of lithium enriched in 6Li is proposed to maximize tritium generation—the fuel for a fusion machine. Advances in superconductors that enable higher power densities may require the use of molten lithium salts for fusion blankets and as coolants. Recent technical advances in these three reactor classes have resulted in increased government and private interest and the beginning of a coordinated effort to address the tritium control challenges in 700°C liquid salt systems. We describe characteristics of salt-cooled fission and fusion machines, the basis for growing interest in these technologies, tritium generation in molten salts, the environment for tritium capture, models for high-temperature tritium transport in salt systems, alternative strategies for tritium control, and ongoing experimental work. In conclusion, several methods to control tritium appear viable. Limited experimental data are the primary constraint for designing efficient cost-effective methods of tritium control.« less

  12. 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

  13. 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.

  14. Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

    NASA Technical Reports Server (NTRS)

    Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

  15. Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

    NASA Technical Reports Server (NTRS)

    Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

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

    PubMed Central

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

    2006-01-01

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

  17. 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.

  18. Health protection: Fluoridation and dental health.

    PubMed Central

    1983-01-01

    Tooth decay, which affects 95 percent of Americans, is our most common health problem, costing an estimated +2 billion yearly for treatment. By the time children reach 17 years of age, 94 percent have experienced caries and 36 percent have lost one or more permanent teeth due to caries. Dental disease prevention embodies the spectrum of many activities from the fluoridation of community and school water supplies to the dental health education of the child and adult. At this stage of our knowledge, the most effective and cost-beneficial intervention is fluoridation. Fluoridation can reduce the incidence of dental caries by about 65 percent, reduce the need for multiple surface fillings, crowns and extractions, and significantly increase the number of children who are completely free of cavities. No other public health measure is as effective in building a decay-resistant tooth while being available to all without regard to education or socio-economic background. The number of people served by fluoridated water systems has increased steadily since its introduction. Currently, however, less than half of all Americans have access to fluoridated water. In areas where community water supplies are not fluoridated, school drinking water is seldom fluoridated despite evidence supporting the efficacy of this procedure. PMID:6414023

  19. Review of fluoride removal from drinking water.

    PubMed

    Mohapatra, M; Anand, S; Mishra, B K; Giles, Dion E; Singh, P

    2009-10-01

    Fluoride in drinking water has a profound effect on teeth and bones. Up to a small level (1-1.5mg/L) this strengthens the enamel. Concentrations in the range of 1.5-4 mg/L result in dental fluorosis whereas with prolonged exposure at still higher fluoride concentrations (4-10mg/L) dental fluorosis progresses to skeletal fluorosis. High fluoride concentrations in groundwater, up to more than 30 mg/L, occur widely, in many parts of the world. This review article is aimed at providing precise information on efforts made by various researchers in the field of fluoride removal for drinking water. The fluoride removal has been broadly divided in two sections dealing with membrane and adsorption techniques. Under the membrane techniques reverse osmosis, nanofiltration, dialysis and electro-dialysis have been discussed. Adsorption, which is a conventional technique, deals with adsorbents such as: alumina/aluminium based materials, clays and soils, calcium based minerals, synthetic compounds and carbon based materials. Studies on fluoride removal from aqueous solutions using various reversed zeolites, modified zeolites and ion exchange resins based on cross-linked polystyrene are reviewed. During the last few years, layered double oxides have been of interest as adsorbents for fluoride removal. Such recent developments have been briefly discussed.

  20. 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

  1. 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

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

    PubMed

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

    2006-09-01

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

  3. Application of fluoride iontophoresis to improve remineralization.

    PubMed

    Kim, H E; Kwon, H K; Kim, B I

    2009-10-01

    Iontophoresis is generally used to maximize the therapeutic action of drugs in medicine. This technique can be used to improve the remineralization effect of topical fluoride applications in dentistry. The aim of this study was to compare the remineralization effect of fluoride iontophoresis (FI) with the conventional fluoride application (CFA) method in vitro. Sixty bovine enamel specimens were divided into three groups: no fluoride treatment, CFA and FI. Fluoride was applied to the demineralized specimens for 4 min in each experimental group. The types of fluoride system used for application were 1.23% acidulated phosphate fluoride gel (12 300 p.p.m. F, pH 3.5) and 2% sodium fluoride solution (9050 p.p.m. F, pH 7) in the experimental groups. All the specimens were then placed in a remineralizing solution for 24 h. This cycle was repeated five times. An iontophoresis device (0.4 mA, 12 V) was used in the FI groups. The efficacy of this technique was evaluated by measuring changes in the surface microhardness and lesion depth of the specimens using confocal laser scanning microscope (CLSM). Data were analysed using anova and Tukey's post hoc test (P < 0.05). Although the FI groups showed higher DeltaVHN than the CFA groups, there were no significant differences between these fluoride application methods (P > 0.05). When the lesion depth was measured using CLSM imaging, there was also no significant difference between the FI and CFA groups (P > 0.05). In conclusion, FI was not significantly superior to CFA in terms of the remineralization effect.

  4. Adverse Effects of High Concentrations of Fluoride on Characteristics of the Ovary and Mature Oocyte of Mouse.

    PubMed

    Yin, Songna; Song, Chao; Wu, Haibo; Chen, Xin; Zhang, Yong

    2015-01-01

    Reproductive toxicity has been an exciting topic of research in reproductive biology in recent years. Soluble fluoride salts are toxic at high concentrations; their reproductive toxicity was assessed in this study by administering different fluoride salt concentrations to mice. Continuous feeding for five weeks resulted in damage to the histological architecture of ovaries. The expression of genes, including Dazl, Stra8, Nobox, Sohlh1, and ZP3 gene, associated with oocyte formation were much lower in the experimental group as compared with the control group. The number of in vitro fertilization of mature oocytes were also much lower in the experimental group as compared with control. Moreover, the fertility of female mice, as assessed by mating with normal male mice, was also lower in experimental compared with control groups. The expression of the oocyte-specific genes: Bmp15, Gdf9, H1oo, and ZP2, which are involved in oocyte growth and the induction of the acrosome reaction, decreased with the fluoride administration. DNA methylation and histone acetylation (H3K18ac and H3K9ac) are indispensable for germline development and genomic imprinting in mammals, and fluoride administration resulted in reduced levels of H3K9ac and H3K18ac in the experimental group as compared with the control group, as detected by immunostaining. Our results indicate that the administration of high concentrations of fluoride to female mice significantly reduced the number of mature oocytes and hampered their development and fertilization. Thus, this study lays a foundation for future studies on fluoride-induced reproductive disorders in women.

  5. 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

  6. A fluoride release-adsorption-release system applied to fluoride-releasing restorative materials.

    PubMed

    Suljak, J P; Hatibovic-Kofman, S

    1996-09-01

    This investigation compared the initial fluoride release and release following refluoridation of three resin-modified glass-ionomer cements (Photac-Fil Applicap, Vitremer, and Fuji II LC) and a new polyacid-modified resin composite material (Dyract). After daily flouride release was measured for 8 days, specimens were refluoridated in 1,000-ppm solutions of fluoride ion for 10 minutes and fluoride release was measured for 5 days. Two further 5-day refluoridation-release periods were carried out. All materials released fluoride initially. Photac released the most; Dyract released the least. Initial release was greatest over the first few days. All materials released significantly more fluoride for 24 to 48 hours after refluoridation. Less fluoride was released with each successive refluoridation for the three glass-ionomer cements. The release from the Dyract compomer remained at a comparatively constant and significantly lower level following each refluoridation.

  7. Electrolyte salts for power sources

    DOEpatents

    Doddapaneni, Narayan; Ingersoll, David

    1995-01-01

    Electrolyte salts for power sources comprising salts of phenyl polysulfonic acids and phenyl polyphosphonic acids. The preferred salts are alkali and alkaline earth metal salts, most preferably lithium salts.

  8. Electrolyte salts for power sources

    DOEpatents

    Doddapaneni, N.; Ingersoll, D.

    1995-11-28

    Electrolyte salts are disclosed for power sources comprising salts of phenyl polysulfonic acids and phenyl polyphosphonic acids. The preferred salts are alkali and alkaline earth metal salts, most preferably lithium salts. 2 figs.

  9. Extended storage-in-place or MSRE fuel salt and flush salt

    SciTech Connect

    Notz, K.J.

    1985-09-01

    The solidified fuel salt and flush salt from the Molten Salt Reactor Experiment (MSRE) have been stored at the Oak Ridge National Laboratory (ORNL) since the reactor was shut down in 1969. The fluoride salt eutectic, containing 37 kg of uranium plus plutonium and fission products, is safely contained in three heavy-walled Hastelloy tanks, which are located inside a reinforced concrete cell. Removal of these salts to a remote location is not feasible until an appropriate repository has been identified, built, and placed in operation. Since this may take many years, extended storage-in-place was critically evaluated. The evaluation, which involved a preliminary assessment of several options for enhancing the integrity of in-place storage, including containment improvements, the addition of chemical getters and neutron poisons, and entombment in concrete, showed that this approach was a rational and safe solution to the problem for the short term. Entombment is essentially nonreversible, but the other options are open-ended; they do not limit the future selection of a final disposal option. Specific actions and improvements that would enhance safe containment during extended storage and would also be of future benefit, regardless of which disposal option is finally selected, were identified. 20 refs., 5 figs., 22 tabs.

  10. 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.

  11. Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation.

    PubMed

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

    2017-10-01

    There are concerns that altered thyroid functioning could be the result of ingesting too much fluoride. Community water fluoridation (CWF) is an important source of fluoride exposure. Our objectives were to examine the association between fluoride exposure and (1) diagnosis of a thyroid condition and (2) indicators of thyroid functioning among a national population-based sample of Canadians. We analysed data from Cycles 2 and 3 of the Canadian Health Measures Survey (CHMS). Logistic regression was used to assess associations between fluoride from urine and tap water samples and the diagnosis of a thyroid condition. Multinomial logistic regression was used to examine the relationship between fluoride exposure and thyroid-stimulating hormone (TSH) level (low/normal/high). Other available variables permitted additional exploratory analyses among the subset of participants for whom we could discern some fluoride exposure from drinking water and/or dental products. There was no evidence of a relationship between fluoride exposure (from urine and tap water) and the diagnosis of a thyroid condition. There was no statistically significant association between fluoride exposure and abnormal (low or high) TSH levels relative to normal TSH levels. Rerunning the models with the sample constrained to the subset of participants for whom we could discern some source(s) of fluoride exposure from drinking water and/or dental products revealed no significant associations. These analyses suggest that, at the population level, fluoride exposure is not associated with impaired thyroid functioning in a time and place where multiple sources of fluoride exposure, including CWF, exist. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  12. Fast Spectrum Molten Salt Reactor Options

    SciTech Connect

    Gehin, Jess C; Holcomb, David Eugene; Flanagan, George F; Patton, Bruce W; Howard, Rob L; Harrison, Thomas J

    2011-07-01

    During 2010, fast-spectrum molten-salt reactors (FS-MSRs) were selected as a transformational reactor concept for light-water reactor (LWR)-derived heavy actinide disposition by the Department of Energy-Nuclear Energy Advanced Reactor Concepts (ARC) program and were the subject of a preliminary scoping investigation. Much of the reactor description information presented in this report derives from the preliminary studies performed for the ARC project. This report, however, has a somewhat broader scope-providing a conceptual overview of the characteristics and design options for FS-MSRs. It does not present in-depth evaluation of any FS-MSR particular characteristic, but instead provides an overview of all of the major reactor system technologies and characteristics, including the technology developments since the end of major molten salt reactor (MSR) development efforts in the 1970s. This report first presents a historical overview of the FS-MSR technology and describes the innovative characteristics of an FS-MSR. Next, it provides an overview of possible reactor configurations. The following design features/options and performance considerations are described including: (1) reactor salt options-both chloride and fluoride salts; (2) the impact of changing the carrier salt and actinide concentration on conversion ratio; (3) the conversion ratio; (4) an overview of the fuel salt chemical processing; (5) potential power cycles and hydrogen production options; and (6) overview of the performance characteristics of FS-MSRs, including general comparative metrics with LWRs. The conceptual-level evaluation includes resource sustainability, proliferation resistance, economics, and safety. The report concludes with a description of the work necessary to begin more detailed evaluation of FS-MSRs as a realistic reactor and fuel cycle option.

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

    PubMed

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

    2008-06-01

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

  14. 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

  15. 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.

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

    PubMed

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

    2014-06-01

    The purpose of this study was to investigate the effect of fluoridated glass fillers on fluoride release, recharge and the flexural properties of modified polymethylmethacrylate (PMMA). Specimens of PMMA denture base material with various loading of fluoridated glass fillers (0%, 1%, 2.5%, 5% and 10% by weight) were prepared. Flexural properties were evaluated on rectangular specimens (n = 10) aged in deionized water after 24 hours, 1 and 3 months. Disc specimens (n = 10) were aged for 43 days in deionized water and lactic acid (pH 4.0) and fluoride release was measured at numerous intervals. After ageing, specimens were recharged and fluoride re-release was recorded at 1, 3 and 7 days after recharge. Samples containing 2.5%, 5% and 10% glass fillers showed significantly (p < 0.05) greater levels of fluoride release compared with the control and 1% glass fillers specimens. All experimental specimens exhibited fluoride release in both media. The flexural strength of specimens decreased in proportion to the percentage filler inclusion with the modulus of elasticity values remaining within ISO Standard 1567. The modified PMMA with fluoridated glass fillers has the ability to release and re-release fluoride ion. Flexural strength decreased as glass filler uploading increased. © 2014 Australian Dental Association.

  17. Fluoride release from an orthodontic glass ionomer adhesive in vitro and enamel fluoride uptake in vivo.

    PubMed

    Chatzistavrou, Evangelia; Eliades, Theodore; Zinelis, Spiros; Athanasiou, Athanasios E; Eliades, George

    2010-04-01

    The objective of this study was to investigate the in-vitro fluoride release from a glass ionomer orthodontic bonding system (Fuji I, GC Corporation, Tokyo, Japan) over a 2-month period and the in-vivo enamel fluoride uptake after 6 months. Ten metal brackets were bonded with either glass ionomer or composite resin (Transbond XT, 3M Unitek, Monrovia, Calif; Light Cure), which served as controls, to recently extracted molars. The bonded teeth, cut at the level of their roots, were stored in distilled water that was renewed after every fluoride measurement at 1, 3, 7, 30, and 60 days. The in-vitro fluoride release was measured by using a fluoride ion-selective electrode, connected to an ion analyzer. Fifteen pairs of premolars were bonded with metal brackets with either the Fuji or the Transbond adhesive. Six months later, the teeth were extracted for orthodontic purposes, embedded in resin, and cross-sectioned, and the fluoride compositions between the outer and bulk enamel surfaces were evaluated with scanning electron microscopy and energy dispersive analysis. The results were analyzed with nonparametric 1-way analysis of variance (ANOVA) on ranks for in-vitro fluoride release and nonparametric 2-way ANOVA on ranks for in-vivo fluoride enamel uptake; group differences were investigated with the Holm-Sidak test at the .05 level. The Spearman rank correlation coefficient test was used to investigate the association between fluoride and aluminum levels in the interfaces of the specimens bonded. The initial burst of fluoride release observed for the Fuji adhesive after the first day of the experiment had a significant decrease with time, and it persisted throughout the monitoring period (60 days) (P <0.05). Fluoride concentrations were found in both the outer and deeper enamel surfaces, with the outer sites having 4 times higher fluoride relative to the bulk for the glass ionomer (P <0.05), and higher fluoride was found in the outer layers for the glass ionomer bonded

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

    PubMed

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

    2008-01-01

    The aim of this in vivo pilot study was to determine the concentration of fluoride retained intra-orally in saliva after flossing with dental floss impregnated with stannous fluoride (SnF(2)). Participants flossed their teeth ad libitum with 2 premeasured lengths of fluoridated dental floss. Expectorated saliva samples were collected in vials before flossing (PF), immediately postflossing(IPF), at 30 minutes (30), and 1 hour (60) after flossing for analysis with a fluoride-specific electrode and an Orion millivoltmeter. Postflossing samples were compared to the preflossing samples using ANOVA and Tukey's HSD. Differences between the PF and IPF group means were found to be statistically significant at p<0.01. No other significant differences were found between or among any of the groups. Salivary fluoride levels at 60 minutes (60) were similar to those prior to flossing (PF). It can be concluded that fluoride can be released from flossing with the tested SnF(2)-impregnated dental floss elevating salivary fluoride levels for at least 30 minutes. Use of this fluoride-containing dental floss offers an option for delivery of fluoride to individuals at risk for dental caries.

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

    PubMed

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

    2013-09-01

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

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

    PubMed

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

    2016-01-01

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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

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

  6. The hydrolysis of glycosyl fluorides by glycosidases

    PubMed Central

    Barnett, J. E. G.; Jarvis, W. T. S.; Munday, K. A.

    1967-01-01

    1. α-d- and β-d-Glucopyranosyl, α-d- and β-d-galactopyranosyl, α-d-mannopyranosyl and α-d-xylopyranosyl fluorides were hydrolysed specifically by the respective glycosidases from several sources. 2. Use of specific inhibitors with a mixture of glycosidases from Helix pomatia intestinal juice showed that each glycosyl fluoride was hydrolysed only by the respective glycosidase. α-d-Glucopyranosidase and α-d-xylopyranosidase activities were shown to be due to different enzymes. 3. Partially purified enzyme preparations containing only one of the glycosidase activities hydrolysed only the corresponding glycosyl fluoride. 4. The configuration at C-1 of α-d-mannopyranosyl fluoride was confirmed since it was hydrolysed by an α-d-mannosidase preparation that contained no detectable β-d-mannosidase activity. 5. An attempt to prepare o-nitrophenyl β-d-mannopyranoside led only to o-nitrophenyl α-d-mannopyranoside. PMID:5584010

  7. Study of fluoride corrosion of nickel alloys

    NASA Technical Reports Server (NTRS)

    Gunther, W. H.; Steindler, M. J.

    1969-01-01

    Report contains the results of an investigation of the corrosion resistance of nickel and nickel alloys exposed to fluorine, uranium hexafluoride, and volatile fission product fluorides at high temperatures. Survey of the unclassified literature on the subject is included.

  8. Synthesis and Crystallization Behavior of Fluoride Glasses

    DTIC Science & Technology

    1989-08-22

    investigator, Professor Uhlmann. It was initiated to explore the feasibility of wet chemical (sol-gel) methods for the synthesis of heavy metal fluoride glasses... synthesis routes to the preparation of metal-organic precursors for heavy metal fluoride glasses were developed. Particular attention was directed to...demonstrated. 8. Using wet chemical synthesis routes based on sol-gel methods , barrier layers having a broad range of chemistries were prepared; and

  9. 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.

  10. [The fight over water fluoridation in Israel].

    PubMed

    Vered, Y; Sgan-Cohen, H

    2002-04-01

    Water fluoridation in Israel was initially introduced on a municipal level in 1981. Legislation in favor of national water fluoridation was approved in 1998. Over the last year an increasing campaign against the fluoridation project has become more and more evident. The material published by the opponents to fluoridation, distributed in pamphlets, daily journals and mass media resources, illustrate as in the USA, an endless and unrestrained "duel" between opponents and supporters of fluoridation. In Israel, in contrast to the USA, referenda are unprecedented, therefore, the political "battle field" is transferred to the municipal authorities and the Knesset. The pivotal component of the Israeli opponents to fluoridation regards the public's health and safety. Unscientific publications appear regularly in the daily journals and electronic mass media with no reference of supporting studies ever mentioned. The inevitable question addressed in this article is what are the best ways of action to be taken by the supporters of fluoridation is Israel. The main and most important mode of action against this campaign is, undoubtedly, continuous persuasion. Nevertheless, the continuous daily struggle of the supporters must be in a world-wide frame and be adjusted to the different target groups of the public. An effective confrontation should include nation-wide available publications (internet, daily papers and multimedia) with special emphasis on the important subjects (e.g. evidence based care, significance of toxic doses and the value of social justice), in a format comprehensible to the public and its leaders. The American experience helps us to understand that the opposition to water fluoridation will not diminished but, on the contrary, is expected to strengthen. We must look forward with no illusions and establish ways of action and cooperation by learning from past experience and from that of our collaborators. This will serve as the basis for the ongoing frank and

  11. 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.

  12. The fluoridation status of U.S. public water supplies.

    PubMed Central

    Löe, H

    1986-01-01

    It has been 40 years since the first community in the United States added a regulated amount of fluoride to its public water supply to prevent tooth decay. Despite the proven benefits of fluoride, today only 61 percent of the U.S. population on public water supplies receives fluoridated water. Progress in fluoridating water is impeded by antifluoridation campaigns and a change in the way Federal funds are allocated for State and local fluoridation programs. Despite profluoridation efforts by the Public Health Service, American Dental Association, and other organizations, the well-publicized claims of fluoride hazards by opponents have prevented many communities from initiating water fluoridation and have caused other communities to discontinue their programs. The law and half a century of research are on the side of fluoridation, as are new scientific findings indicating that optimal amounts of fluoride may reduce the incidence or severity of osteoporosis. PMID:3083470

  13. Comparative uptake of fluoride ion into enamel from various topical fluorides in vitro.

    PubMed

    Pai, N; McIntyre, J; Tadic, N; Laparidis, C

    2007-03-01

    There are many forms of topical fluoride available today, making the decision as to which is most effective to manage the immediate caries risk problem at hand, very difficult. The objective of this project was to determine the concentration and pattern of fluoride ion uptake into enamel from a variety of categories of topical fluoride recently available in Australia. Extracted, intact molar teeth were sectioned to provide six plates of smooth surface enamel. Windows of enamel 2 x 6 mm were exposed to a variety of topical fluorides for periods simulating those used in vivo. Following drying, the slates of enamel were exposed to 2 ml of 0.1 M HCl as a chemical biopsy agent for incremental periods of time. The concentrations of fluoride ion in the biopsy solutions for both test and background (control) slates of enamel were determined directly using a fluoride combination selective electrode in conjunction with a high impedance pH meter. Cumulative amounts of fluoride were determined for each topical fluoride agent. The concentrations of fluoride ion taken up into enamel were generally proportional to those present in each agent. However, those from APF gel greatly exceeded the amounts taken up from NaF gel. Also, the concentrations taken up from some of the highly concentrated metal fluorides were surprisingly low. Prior etching of enamel increased uptake and prolonged application of APF gel provided no extra benefit. Some topical fluorides, e.g., APF gel, provided a greatly increased uptake and to a greater depth than other self-application products. However, the frequency of its use should be considered with caution where patients have glass-based restorations.

  14. Debating Water Fluoridation Before Dr. Strangelove

    PubMed Central

    2015-01-01

    In the 1930s, scientists learned that small amounts of fluoride naturally occurring in water could protect teeth from decay, and the idea of artificially adding fluoride to public water supplies to achieve the same effect arose. In the 1940s and early 1950s, a number of studies were completed to determine whether fluoride could have harmful effects. The research suggested that the possibility of harm was small. In the early 1950s, Canadian and US medical, dental, and public health bodies all endorsed water fluoridation. I argue in this article that some early concerns about the toxicity of fluoride were put aside as evidence regarding the effectiveness and safety of water fluoridation mounted and as the opposition was taken over by people with little standing in the scientific, medical, and dental communities. The sense of optimism that infused postwar science and the desire of dentists to have a magic bullet that could wipe out tooth decay also affected the scientific debate. PMID:26066938

  15. 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.

  16. Feasibility of the electrochemical way in molten fluorides for separating thorium and lanthanides and extracting lanthanides from the solvent

    NASA Astrophysics Data System (ADS)

    Chamelot, P.; Massot, L.; Hamel, C.; Nourry, C.; Taxil, P.

    2007-01-01

    An alternative way of reprocessing nuclear fuel by hydrometallurgy could be using treatment with molten salts, particularly fluoride melts. Moreover, one of the six concepts chosen for GEN IV nuclear reactors (Technology Roadmap - http://gif.inel.gov/roadmap/) is the molten salt reactor (MSR). The originality of the concept is the use of molten salts as liquid fuel and coolant. During the running of the reactor, fission products, particularly lanthanides, accumulate in the melt and have to be eliminated to optimise reactor operation. This study concerns the feasibility of the separation actinides-lanthanides-solvent by selectively electrodepositing the elements to be separated on an inert (Mo, Ta) or a reactive (Ni) cathodic substrate in molten fluoride media. The main results of this work lead to the conclusions that: The solvents to be used for efficient separation must be fluoride media containing lithium as cation. Inert substrates are suitable for actinide/lanthanide separation; nickel substrate is more suitable for the extraction of lanthanides from the solvent, owing to the depolarisation occurring in the cathodic process through alloy formation.

  17. Fluoride use in periodontal therapy: a review of the literature.

    PubMed

    Paine, M L; Slots, J; Rich, S K

    1998-01-01

    Although the relationship between fluoride and dental caries has been widely studied and definitively determined, the relationship between fluoride and periodontal health and disease is not clear. Conflicting studies in the literature either suggest routine fluoride usage as an adjunct to conventional periodontal therapy or argue against topical fluoride use on periodontally involved teeth. This review summarizes the literature that addresses the utility of fluoride in patients with periodontal disease and aims to advance a rational criterion for the use of fluorides in the management of periodontal diseases.

  18. Widespread Genetic Switches and Toxicity Resistance Proteins for Fluoride

    PubMed Central

    Weinberg, Zasha; Roth, Adam; Stockbridge, Randy B.; Breaker, Ronald R.

    2014-01-01

    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. PMID:22194412

  19. 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.

  20. Measurement of solubility of plutonium trifluoride and rare-earth fluorides in molten LiF-BeF{sub 2}-ZrF{sub 4}

    SciTech Connect

    Naumov, V.S.; Bychkov, A.V.; Kormilitsyn, M.V.

    1996-12-01

    Data on behavior of plutonium fluoride and fission products (FP) dissolved in fuel composition are needed to calculate the duration of an operating cycle of the ADTT facility (Accelerator-Driver Transmutation Technologies) and to determine the effect of their equilibrium concentrations on nuclear-physical characteristics of reactor operation. The data on the FP fluoride solubility in the molten salts are of great important for some industrial processes (electrolytical metal deposition, development of physical-chemical mean for processes of chemical technology, etc.) As noted above, some information on this question is given in monography and articles. Data concerning fluoride salts are given in reports. However, it was impossible to make the substantial analysis of mutual solubility of fluoride melts. The primary investigation of CeF{sub 3} and neodymium, samarium and lanthanum fluorides showed that the solubility of the melt LiF-BeF{sub 2} and LiF-BeF{sub 2}-ThF{sub 4} was a linear function of reverse temperature and increases from lanthanum to samarium in the row of rare-earth elements. Disagreement in estimation of plutonium trifluoride solubility and incomplete data on the solubility of rare-earth elements prompted this study.

  1. 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.

  2. 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.

  3. Fluoride uptake by proximal surfaces from professionally applied fluorides: an in vitro study.

    PubMed

    Kohli, K; Houpt, M; Shey, Z

    1997-01-01

    This study was performed to examine the uptake of fluoride by mesial enamel surfaces of extracted teeth from different types of topical fluoride. Forty-eight extracted human molars and twelve premolars were randomly divided into four groups and mounted in twelve wax blocks with five teeth in proximal contact in each block. Each group was treated for four minutes with either 1.23 percent acidulated phosphofluoride conventional gel, thixotropic gel, or foam in lined trays, or 2 percent neutral sodium fluoride solution applied with a cotton tip applicator. Acid-etch biopsies were performed three times to indicate the amount of fluoride uptake at three different depths. The results demonstrated that there was a statistically significant increase in fluoride uptake in the surface layer with both gels and foam (1150, 1058 and 1120 ppm F), whereas there was an insignificant increase with the fluoride solution (27 ppm F). In the deepest layer, the thixotropic fluoride produced the greatest fluoride uptake (919 ppm F) in comparison with the uptake from conventional gel (383 ppm F), foam (297 ppm F), or solution (118 ppm F).

  4. Renal fluoride excretion in children following topical application of fluoride varnish.

    PubMed

    García-Hoyos, F; Barbería, E; García-Camba, P; Varela, M

    2012-12-01

    To demonstrate that the application of dental fluoride varnishes in children increases urinary fluoride excretion. From a randomly assembled group of 42 children aged between 5 and 8 years, residing in a community with non-fluoridated water, spot urinary samples were taken before the topical application of dental fluoride varnish and 2 hours afterwards. In an age-matched control group of 16 children from the same community, who received no treatment, samples were taken the same way. The urinary excretion of fluoride was analysed by determining fluoride ion (F-) level and fluoride/creatinine (F/Cr) ratio in the urine. In the study group, the average pre- and post-treatment F/Cr ratios were 0.42 and 1.38 mg/g, respectively (p < .001). No significant changes were observed in the control group, which received no treatment. The average 2 hours afterward F/Cr ratios were 0.29 and 0.27 respectively (p = 0.426). The topical application of dental fluoride varnish leads to a significant increase in urine F-, which is attributable to the application of the product.

  5. 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.

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

    PubMed

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

    2000-03-01

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

  7. Molten Salt Fuel Cycle Requirements for ADTT Applications

    SciTech Connect

    Williams, D. F.; Del Cul, G. D.; Toth, L. M.

    1999-06-07

    The operation of an ADT system with the associated nuclear reactions has a profound effect upon the chemistry of the fuel - especially with regards to container compatibility and the chemical separations that may be required. The container can be protected by maintaining the redox chemistry within a relatively narrow, non-corrosive window. Neutron economy as well as other factors require a sophisticated regime of fission product separations. Neither of these control requirements has been demonstrated on the scale or degree of sophistication necessary to support an ADT device. We review the present situation with respect to fluoride salts, and focus on the critical issues in these areas which must be addressed. One requirement for advancement in this area - a supply of suitable materials - will soon be fulfilled by the remediation of ORNL's Molten Salt Reactor Experiment, and the removal of a total of 11,000 kg of enriched (Li-7 > 99.9%) coolant, flush, and fuel salts.

  8. Sources of dietary fluoride intake in 6-7-year-old English children receiving optimally, sub-optimally, and non-fluoridated water.

    PubMed

    Zohouri, Fatemeh V; Maguire, Anne; Moynihan, Paula J

    2006-01-01

    Due to increased consumption of pre-packaged drinks, tap water may no longer be the principal source of water intake and consequently fluoride intake. Little is known about the importance of solid foods as fluoride sources and how the relative contribution of foods/drinks to fluoride intake is affected by residing in fluoridated or non-fluoridated areas. This study investigated the relative contributions of different dietary sources to dietary fluoride intake and compared this in children residing in optimally artificially fluoridated, sub-optimally artificially fluoridated, and non-fluoridated areas. Thirty-three healthy children aged 6 years were recruited from fluoridated and non-fluoridated communities and categorised into three groups based on fluoride content of home tap water: optimally fluoridated (< or =0.7 mgF/L), sub-optimally fluoridated (> or =0.3 to < or =0.7 mgF/L) and non-fluoridated (50.3 mgF/L) drinking water. A 3-day dietary diary collected dietary information. Samples of foods/drinks consumed were collected and analyzed for fluoride content. Drinks provided 59%, 55% and 32% of dietary fluoride intake in optimally, sub-optimally and non-fluoridated areas respectively. Tap water, fruit squashes and cordials (extremely sweet non-alcoholic fruit flavoured drink concentrates) prepared with tap water, as well as cooked rice, pasta and vegetables were important sources of fluoride in optimally and sub-optimally fluoridated areas. Carbonated soft drinks and bread were the most important contributors to dietary fluoride intake in the non-fluoridated area. The main contributory sources to dietary fluoride differ between fluoridated and non-fluoridated areas. Estimating total fluoride intake from levels of fluoride in tap water alone is unlikely to provide a reliable quantitative measure of intake. Studies monitoring dietary fluoride exposure should consider intake from all foods and drinks.

  9. Pit and fissure sealants or fluoride varnishes?

    PubMed

    Paglia, L

    2016-09-01

    Despite the general advances in dental care, dental caries is still a global health problem affecting many children. Occlusal surfaces of first permanent molars are the most susceptible sites in the developing permanent dentition. Dentists should use sealants or fluoride varnish - as well as other means - to limit the onset of tooth decay. Application of sealants is a recommended procedure to prevent or control caries. Sealing occlusal surfaces of newly erupted permanent molars in children and teenagers delays caries onset up to 48 months compared with unsealed teeth. However longer follow-ups shows a reduction of the preventive effect [Tikhonova et al., 2015]. A review of 2013 pointed out how sealants are effective in high risk children, however information about the benefits of sealing in other conditions is still scant [Ahovuo-Saloranta et al., 2013]. Fluoride varnishes are frequently used to prevent early childhood caries and reduce caries increment in very young children [Weintraub et al., 2006] and in the most vulnerable populations, where the prevalence of caries is higher and specialist visits are occasional [Chu et al., 2010]. Many studies have reported the effectiveness of different types and forms of fluoride agents in preventing dental caries among children and adolescents [Divaris et al., 2013]. A review clarifies that professional application of a 5% sodium fluoride varnish leads to remineralisation of early enamel caries in children. Solutions of 38% silver diamine fluoride are effective in arresting active dentine caries [Gao et al., 2016]. The last systematic review [Ahovuo-Saloranta et al., 2016], comparing pit and fissure sealants with fluoride varnishes explains that the pooled estimate slightly favours resin sealants over fluoride varnishes at two years. At four and nine years, the only comparative study (with high drop-out rates) found more caries on fluoride-varnished occlusal surfaces than on resin-sealed surfaces. There is evidence

  10. 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

  11. [Remineralization of artificial root caries by fluoride dentifrice of different fluoride concentration in vitro].

    PubMed

    Liu, Hong-Chun; Yu, Shao-Jie; Hu, De-Yu

    2010-12-01

    Although the effectiveness of fluoride dentifrice in remineralizing enamel caries has been established, the optimum fluoride concentration for remineralization root caries has not been defined. The aim of this study was to assess and compare the effect of 1.1g/L, 1.45g/L and 5g/L fluoride dentifrices in remineralization of artificial root caries. Sound human tooth fragments obtained from the cervical portion of root were stored in a demineralization solution for 96h at 37 degrees centigrade to induce artificial root caries lesions. The fragments were then randomly divided into four treatment groups including 1.1g/L, 1.45g/L, 5g/L fluoride dentifrice group and non-fluoride dentifrice control group. The demineralized samples were pH-cycled through treatment solutions, acidic buffer and neutral buffer for 8 days at 6 cycles per day. The samples were evaluated using electrical caries monitor(ECM), polarized light microscopy (PLM) and confocal laser scanning microscopy (CLSM). The data was analyzed using ANOVA with SPSS13.0 software package. Variations of LgECM, total fluorescence and average fluorescence from CLSM after remineralization in fluoride dentifrice groups were significantly higher than those in the control group(P<0.05) Variations of LgECM, total fluorescence and average fluorescence from CLSM after remineralization in the 5g/L fluoride dentifrice group were significantly higher than those in the 1.1g/L and 1.45g/L fluoride dentifrice groups(P<0.05). PLM observation showed that a banding or deposit of mineral appeared within the lesions of specimens in the fluoride dentifrice groups. A wider mineral band was seen in the 5g/L fluoride dentifrice group than in the 1.1g/L and 1.45g/L fluoride dentifrice groups. Fluoride dentifrice is effective in remineralizing artificial root caries and 5g/L fluoride dentifrice has better effect than 1.1g/L and 1.45g/L fluoride dentifrices.

  12. 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.

  13. 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

  14. 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

  15. Salt tectonics on Venus

    SciTech Connect

    Wood, C.A.; Amsbury, D.

    1986-05-01

    The discovery of a surprisingly high deuterium/hydrogen ratio on Venus immediately led to the speculation that Venus may have once had a volume of surface water comparable to that of the terrestrial oceans. The authors propose that the evaporation of this putative ocean may have yielded residual salt deposits that formed various terrain features depicted in Venera 15 and 16 radar images. By analogy with models for the total evaporation of the terrestrial oceans, evaporite deposits on Venus should be at least tens to hundreds of meters thick. From photogeologic evidence and in-situ chemical analyses, it appears that the salt plains were later buried by lava flows. On Earth, salt diapirism leads to the formation of salt domes, anticlines, and elongated salt intrusions - features having dimensions of roughly 1 to 100 km. Due to the rapid erosion of salt by water, surface evaporite landforms are only common in dry regions such as the Zagros Mountains of Iran, where salt plugs and glaciers exist. Venus is far drier than Iran; extruded salt should be preserved, although the high surface temperature (470/sup 0/C) would probably stimulate rapid salt flow. Venus possesses a variety of circular landforms, tens to hundreds of kilometers wide, which could be either megasalt domes or salt intrusions colonizing impact craters. Additionally, arcurate bands seen in the Maxwell area of Venus could be salt intrusions formed in a region of tectonic stress. These large structures may not be salt features; nonetheless, salt features should exist on Venus.

  16. 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.

  17. 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)

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

    PubMed

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

    2016-07-01

    The long-term capability of resin sealants and glass ionomer cements to release fluoride is associated to a reduction in pit and fissure caries. The regular use of fluoride varnishes/toothpastes can result in the absorption of fluoride into the sealant. The objective of the present study was to assess the fluoride release/uptake capacities of different fissure sealants. Three different fissure sealants (Fuji Triage/GC, Fissurit FX/Voco and Grandio Seal/Voco) were examined. Ten discs of each material were prepared. Each disc was incubated with distilled water and then the solution analyzed for diluted for fluoride concentration, using a combination of fluoride electrode (OrionGP 1 S/N 13824, Orion Research Inc, Boston, MA, USA) connected to an expandable ion analyzer (Orion 720A, Orion Research Inc, Boston, MA, USA). Standard curves between 1 and 100 ppm F- were used to calibrate the electrode. Cumulative fluoride release was measured on days 1, 2, 3, 5, 7, 21, 35 and 49, then two different fluoride varnishes/pastes (Profluorid Varnish/Voco, MI Paste Plus/GC), were applied to the sealants tested, and fluoride release (after reuptake) was measured on days 56, 70 and 84. Kruskal Wallis test confirmed significant differences in fluoride release between Fuji Triage/GC and Fissurit FX/Voco and Grandio Seal/Voco from day 1 (P < 0.001). The application of fluoride varnish Profluorid Varnish enhanced the fluoride release for all sealants (P < 0.05). MI Paste Plus enhanced the fluoride release for all sealants except for Fuji Triage/GC (P > 0.05). The GIC-based sealant (Fuji Triage/GC) released significantly more fluoride than the resin sealants tested. The exposure to the fluoridated varnish (Profluorid Varnish) significantly recharged the sealants tested more than the CPP-ACPF toothpaste (MI Paste Plus). Fissure sealants, fluoride release, fluoride uptake, glass ionomer cements.

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

    PubMed

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

    2017-06-01

    Fluoride has been widely used for the prevention of dental caries since the mid-20th century. The aim of this study was to investigate the chronologic trends in studies on fluoride mechanisms of action against dental caries during the years 1950 to 2015. To this aim, queries such as "fluoride," "fluoride and demineralization," "fluoride and remineralization," "fluoride and (plaque or biofilms)," and "fluoride and (bacteria or microbials)" were submitted to PubMed to collect research article information, including titles, abstracts, publication dates, author affiliations, and publication journals. The article information that PubMed produced was then collected by an automatic web crawler and examined through informetrics and linguistic analyses. We found that the number of articles concerned with fluoride mechanisms of action against dental caries was 6,903 and gradually increased over time during the years 1950 to 2015. They were published by 1,136 journals-most notably, Caries Research and Journal of Dental Research. Of the articles published, those related to bacteria/microbials had a higher percentage (44%) than those dealing with plaque/biofilms, demineralization, and remineralization. With regard to the geographic distribution of authors, Europe and North America accounted for 65% of the articles during the years 1987 to 2015, although the number of authors in Asia sharply increased in recent years. Among the fluoride compounds, NaF was mentioned more frequently than SnF2, Na2PO3F, amine fluoride, and acidulated phosphate fluoride during the years 1986 to 2015. Water fluoridation received the most attention among the various fluoride application methods (toothpastes, mouthwashes, fluoride varnishes, and fluoride gels) during the same period. These results, obtained from employing informetrics and linguistic analyses, suggest that in studies on fluoride mechanisms of action, 1) the unbalanced geographic distribution of articles and 2) the heavy concentration of

  20. Molten salt electrolyte separator

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    A molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication.

  1. Retrospective salt tectonics

    SciTech Connect

    Jackson, M.P.A.

    1996-12-31

    The conceptual breakthroughs in understanding salt tectonics can be recognized by reviewing the history of salt tectonics, which divides naturally into three parts: the pioneering era, the fluid era, and the brittle era. The pioneering era (1856-1933) featured the search for a general hypothesis of salt diapirism, initially dominated by bizarre, erroneous notions of igneous activity, residual islands, in situ crystallization, osmotic pressures, and expansive crystallization. Gradually data from oil exploration constrained speculation. The effects of buoyancy versus orogeny were debated, contact relations were characterized, salt glaciers were discovered, and the concepts of downbuilding and differential loading were proposed as diapiric mechanisms. The fluid era (1933-{approximately}1989) was dominated by the view that salt tectonics resulted from Rayleigh-Taylor instabilities in which a dense fluid overburden having negligible yield strength sinks into a less dense fluid salt layer, displacing it upward. Density contrasts, viscosity contrasts, and dominant wavelengths were emphasized, whereas strength and faulting of the overburden were ignored. During this era, palinspastic reconstructions were attempted; salt upwelling below thin overburdens was recognized; internal structures of mined diapirs were discovered; peripheral sinks, turtle structures, and diapir families were comprehended; flow laws for dry salt were formulated; and contractional belts on divergent margins and allochthonous salt sheets were recognized. The 1970s revealed the basic driving force of salt allochthons, intrasalt minibasins, finite strains in diapirs, the possibility of thermal convection in salt, direct measurement of salt glacial flow stimulated by rainfall, and the internal structure of convecting evaporites and salt glaciers. The 1980`s revealed salt rollers, subtle traps, flow laws for damp salt, salt canopies, and mushroom diapirs.

  2. 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.

  3. The influence of saliva on the dissolution of calcium fluoride after application of different fluoride gels in vitro.

    PubMed

    Hellwig, Elmar; Polydorou, Olga; Lussi, Adrian; Kielbassa, Andrej M; Altenburger, Markus J

    2010-10-01

    To determine the formation and dissolution of calcium fluoride on the enamel surface after application of two fluoride gel-saliva mixtures. From each of 80 bovine incisors, two enamel specimens were prepared and subjected to two different treatment procedures. In group 1, 80 specimens were treated with a mixture of an amine fluoride gel (1.25% F-; pH 5.2; 5 minutes) and human saliva. In group 2, 80 enamel blocks were subjected to a mixture of sodium fluoride gel (1.25% F; pH 5.5; 5 minutes) and human saliva. Subsequent to fluoride treatment, 40 specimens from each group were stored in human saliva and sterile water, respectively. Ten specimens were removed after each of 1 hour, 24 hours, 2 days, and 5 days and analyzed according to potassium hydroxide-soluble fluoride. Application of amine fluoride gel resulted in a higher amount of potassium hydroxide-soluble fluoride than did sodium fluoride gel 1 hour after application. Saliva exerted an inhibitory effect according to the dissolution rate of calcium fluoride. However, after 5 days, more than 90% of the precipitated calcium fluoride was dissolved in the amine fluoride group, and almost all potassium hydroxide-soluble fluoride was lost in the sodium fluoride group. Calcium fluoride apparently dissolves rapidly, even at almost neutral pH. Considering the limitations of an in vitro study, it is concluded that highly concentrated fluoride gels should be applied at an adequate frequency to reestablish a calcium fluoride-like layer.

  4. 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)

  5. 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.

  6. Expansion of the proper use of systemic fluoride supplements.

    PubMed

    Levy, S M

    1986-01-01

    Systemic fluoride supplements, such as tablets and drops, are recommended as alternatives to community and school water fluoridation. Assay of patients' drinking water should be used to determine the water fluoride content. Supplements should be used only when the water fluoride level is found to be deficient. In this way, the appropriate dosage supplement can be determined and prescribed, and unnecessary risks of fluorosis can be avoided. Research has shown that many practitioners prescribe fluoride supplements, although relatively few practitioners assay patients' water supplies. Increased use of water assay and fluoride supplements is warranted if the dental profession is to continue its emphasis on prevention. This increase should be in conjunction with water fluoridation, topical fluorides, and pit and fissure sealants.

  7. Priorities to preserve fluoride uses: rationales and strategies.

    PubMed

    Frazier, P J

    1985-01-01

    Well-planned, new initiatives are required to preserve fluoride uses, especially water fluoridation. Discussed are barriers to fluoride promotion, evidence about public and health-care providers' knowledge and opinions about fluoride use and decision making, implications of sources of public information on fluorides, consequences to professionals and the public of being misinformed about fluorides, and four general strategies for promoting fluorides under varying conditions. Educational and political initiatives must be appropriate to state needs and conditions. Four broad categories of actions include: diagnosis and planning for education/promotion; public and professional education under both noncontroversial and controversial conditions, political persuasion where required, and changing the context of fluoridation decision making to prevent public referenda on public health measures.

  8. 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)

  9. 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.

  10. 21 CFR 100.155 - Salt and iodized salt.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Salt and iodized salt. 100.155 Section 100.155... FOR HUMAN CONSUMPTION GENERAL Specific Administrative Rulings and Decisions § 100.155 Salt and iodized salt. (a) For the purposes of this section, the term iodized salt or iodized table salt is...

  11. 21 CFR 100.155 - Salt and iodized salt.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Salt and iodized salt. 100.155 Section 100.155... FOR HUMAN CONSUMPTION GENERAL Specific Administrative Rulings and Decisions § 100.155 Salt and iodized salt. (a) For the purposes of this section, the term iodized salt or iodized table salt is...

  12. 21 CFR 100.155 - Salt and iodized salt.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Salt and iodized salt. 100.155 Section 100.155... FOR HUMAN CONSUMPTION GENERAL Specific Administrative Rulings and Decisions § 100.155 Salt and iodized salt. (a) For the purposes of this section, the term iodized salt or iodized table salt is...

  13. 21 CFR 100.155 - Salt and iodized salt.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Salt and iodized salt. 100.155 Section 100.155... FOR HUMAN CONSUMPTION GENERAL Specific Administrative Rulings and Decisions § 100.155 Salt and iodized salt. (a) For the purposes of this section, the term iodized salt or iodized table salt is...

  14. 21 CFR 100.155 - Salt and iodized salt.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Salt and iodized salt. 100.155 Section 100.155... FOR HUMAN CONSUMPTION GENERAL Specific Administrative Rulings and Decisions § 100.155 Salt and iodized salt. (a) For the purposes of this section, the term iodized salt or iodized table salt is...

  15. Relationship of naturally occurring fluoride in Carroll County, Maryland to aquifers, well depths, and fluoride supplementation prescribing behaviors.

    PubMed

    Osso, Diane; Tinanoff, Norman; Romberg, Elaine; Syme, Sheryl; Roberts, Michael

    2008-01-01

    Systemic fluorides are effective in the prevention of dental caries but over ingestion can lead to dental fluorosis. Fluoride supplements may be under-prescribed for children residing in areas where drinking water is derived from wells, because of a lack of knowledge of dental providers or the effort required to test wells for fluoride before prescribing supplements. The purpose of this study was to determine the possible factors associated with fluoride content of well water in a specific county in Maryland, and to determine whether there is a relationship between the amount of naturally occurring fluoride in the well water and the child's fluoride supplementation use. This study analyzed the fluoride prescribing behavior and the fluoride content of wells from a sample of 197 Carroll County, Md residents. Those individuals that answered a questionnaire about well depth and use of fluoride supplements subsequently were mailed a water testing kit. Water samples were tested for fluoride using a fluoride specific ion electrode. Derivations of well water supplies (aquifers) were obtained from a county geologist. Variance in well depth and aquifer type were correlated to the levels of naturally occurring fluoride. Supplementation practices of children residing in the participating sampled households were compared to results of fluoride analyses of individual wells. Results showed that Carroll County well water contains negligible to low levels of fluoride (0.08-0.24 ppm). Pearson r testing showed a positive relationship between well depth and fluoride, r = 0.23 (p < or = .01). ANOVA results showed no significant difference between the 3 aquifers fluoride, p = 0.23. Analysis of the supplementation behavior indicated that the majority (58%) of the children that should have received fluoride supplements were receiving the incorrect dosage or not being supplemented. Fluoride content of well water may be related to well depths. Fluoride supplementation practices generally

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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)

  1. 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

  2. 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

  3. 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.

  4. Fluoride and silver concentrations of silver diammine fluoride solutions for dental use.

    PubMed

    Mei, May Lei; Chu, Chun Hung; Lo, Edward Chin Man; Samaranayake, Lakshman Perera

    2013-07-01

    To determine the short-term stability of free fluoride ion concentrations and acidity (pH values) of three commercially available SDF solutions over time. Three SDF products for caries control were studied: Cariestop-12%, Cariestop-30% and Saforide-38%. Their expected fluoride ion concentrations were 14,200, 35,400 and 44,800 ppm, respectively. The fluoride ion concentrations were determined with an ion-selective electrode. The acidity was determined with a pH electrode. The measurements were performed when open and at 7 and 28 days. The mean fluoride ion concentrations of the freshly opened bottles were 12,525 ± 450, 13,200 ± 2060 and 55,800 ± 2536 ppm, respectively. The mean pH values were 9.4 ± 0.1, 10.4 ± 0.1 and 10.2 ± 0.2, respectively. No significant change (P > 0.05) in the fluoride ion concentrations or the acidity was detected after 7 or 28 days. The three SDF tested solutions were alkaline. The fluoride ion concentrations of Cariestop-30% and Saforide-38% were considerably different. The fluoride ion concentrations and acidity of the products demonstrated a short-term stability over 28 days. © 2012 John Wiley & Sons Ltd, BSPD and IAPD.

  5. 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. © 2014 S. Karger AG, Basel.

  6. A 2-year report on caries prevention by fluoride varnishes in a community with fluoridated water.

    PubMed

    Seppä, L; Tuutti, H; Luoma, H

    1981-04-01

    The benefit of semi-annual applications of sodium fluoride varnish (Duraphat) and silane fluoride varnish (Fluor Protector) was studied in 11-13 year-old children with life-long exposure to fluoridated drinking water (1-1.2 parts/10(6)). Annual clinical and radiographic examinations were made on 67 children in the Duraphat group and 71 children in the Fluor Protector group. Fluoride varnish was applied semi-annually using the half-mouth technique. At the end of 2 years, the mean overall DMFS-increments on the control side and test side of the Duraphat group were 5.0 and 3.8 (p less than 0.01), respectively, and of the Fluor Protector group 3.7 and 3.3 (NS). The caries reductions were 24% and 12%, respectively. Since there were no differences between initial mean DMFS scores of the groups, it was assumed that lower increments in the Fluor Protector group were due to Fluoride ions crossing the midline and providing protection on the control side as well. When increments in the Duraphat control side and the Fluor Protector test side were compared, the caries reduction of Fluor Protector was 35% (p less than 0.01). Fluoride varnishes provide additional benefit even when fluoride intake from drinking water is optimal.

  7. 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.

  8. Transmutation Scoping Studies for a Chloride Molten Salt Reactor

    SciTech Connect

    Heidet, Florent; Feng, Bo; Kim, Taek; Taiwo, Temitope

    2016-01-01

    Over the past few years, there has been strong renewed interest from private industry, mostly from start-up enterprises, in molten salt reactor (MSR) technologies because of the unique properties of this class of reactors. These are reactors in which the fuel is homogeneously mixed with the coolant in the form of liquid salts and is circulated continuously into and out of the active core region with on-line fuel management, salt treatment, and salt processing. In response to such wide-spread interest, Argonne National Laboratory is expanding its well-established reactor modelling and simulation expertise and infrastructure to enable detailed analysis and design of MSRs. The tools being developed are able to simulate the continuous fuel flow, the complex on-line fuel management and elemental removal processes (e.g., fission product removal) using depletion steps representative of a real MSR system. Leveraging these capabilities, a parametric study on the transmutation performance of a simplified actinide-burning MSR concept that uses a chloride-based salt was performed. This type of salt has attracted attention over the more commonly discussed fluoride-based salts since no tritium is produced as a result of irradiation and it is compatible with a fast neutron spectrum. The studies discussed in this paper examine the performance of a burner MSR design with a fixed core size and power density over a range of possible fuel salt molar ratios with NaCl-MgCl2 as the carrier salt. The intent is to quantify the impact on the required transuranics content of the make-up fuel, the actinide transmutation rates, and other performance characteristics for typical burner MSR designs.

  9. Evaluation of Fluorine-Trapping Agents for Use During Storage of the MSRE Fuel Salt

    SciTech Connect

    Brynestad, J.; Williams, D.F.

    1999-05-01

    A fundamental characteristic of the room temperature Molten Salt Reactor Experiment (MSRE) fuel is that the radiation from the retained fission products and actinides interacts with this fluoride salt to produce fluorine gas. The purpose of this investigation was to identify fluorine-trapping materials for the MSRE fuel salt that can meet both the requirement of interim storage in a sealed (gastight) container and the vented condition required for disposal at the Waste Isolation Pilot Plant (WIPP). Sealed containers will be needed for interim storage because of the large radon source that remains even in fuel salt stripped of its uranium content. An experimental program was undertaken to identify the most promising candidates for efficient trapping of the radiolytic fluorine generated by the MSRE fuel salt. Because of the desire to avoid pressurizing the closed storage containers, an agent that traps fluorine without the generation of gaseous products was sought.

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

    PubMed Central

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

    2014-01-01

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

  11. 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. Copyright © 2014 by the American Academy of Pediatrics.

  12. 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.

  13. Intraoral fluoride levels after use of conventional and high-fluoride dentifrices.

    PubMed

    Pessan, Juliano P; Conceição, Juliana M; Grizzo, Larissa T; Székely, Melinda; Fazakas, Zita; Buzalaf, Marília Ar

    2015-05-01

    This study aimed to evaluate saliva and plaque as indicators of intraoral fluoride (F) levels after the use of conventional and high-fluoride dentifrices. Subjects were randomly assigned to brush their teeth with conventional (1000 ppm F), high-fluoride (5000 ppm F), and placebo dentifrices (fluoride free) for 10 days, following a double-blind, crossover protocol. Saliva and plaque samples were collected on the morning of the 5(th) and 10th days, respectively at 1 and 12 h after brushing, and analyzed with an ion-selective electrode after HMDS-facilitated diffusion. Data were analyzed by two-way repeated measures ANOVA, Tukey's test and Spearman's correlation coefficient (p < 0.05). Plaque and salivary F levels were significantly increased after the use of conventional and high-fluoride dentifrices when compared to values obtained for placebo, except plaque 12 h after the use of conventional dentifrice. A positive and significant correlation was found between fluoride concentrations in plaque and saliva for both times of sample collection. Both indicators assessed were able to detect significant differences among treatments and between times after brushing. The use of a high-fluoride dentifrice is able to significantly increase intraoral fluoride levels throughout the day, being therefore a useful therapy for patients at high caries risk. A dentifrice with high fluoride concentration could be regarded as a useful therapy of F delivery for high caries-risk patients, since intraoral F levels were sustained throughout most of the day after using this formulation.

  14. Enhancement of fluoride release from glass ionomer cement following a coating of silver fluoride.

    PubMed

    Ariffin, Z; Ngo, H; McIntyre, J

    2006-12-01

    This study investigated the extent to which a coating of 10% silver fluoride (AgF) on discs of glass jonomer cements (GIGs) would enhance the release of fluoride ion into eluting solutions at varying pH. Forty discs each of Fuji LX, Fuji VII and of Vitrebond were prepared in a plastic mould. Twenty discs of each material were coated for 30 seconds with a 10% solution of AgF. Five discs each of coated and uncoated material were placed individually in 4m1 of differing eluant solutions. The eluant solutions comprised deionized distilled water (DDW) and three separate acetate buffered solutions at pH 7, pH 5 and pH 3. After 30 minutes the discs were removed and placed in five vials containing 4m1 of the various solutions for a further 30 minutes. This was repeated for further intervals of time up to 216 hours, and all eluant solutions were stored. Fluoride concentrations in the eluant solutions were estimated using a fluoride specific electrode, with TISAB IV as a metal ion complexing and ionic concentration adjustment agent. Cumulative fluoride release patterns were determined from the incremental data. The coating of AgF greatly enhanced the level of fluoride ion release from all materials tested. Of the uncoated samples, Vitrehond released the greater concentrations of fluoride ion, followed by Fuji VII. However, cumulative levels of fluoride released from coated samples of the GICs almost matched those from coated Vitrebond. It was concluded that a coating of 10% AgF on GICs and a resin modified GIC greatly enhanced the concentration of fluoride released from these materials. This finding might be applied to improving protection against recurrent caries, particularly in high caries risk patients, and in the atraumatic restorative technique (ART) of restoration placement.

  15. 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.

  16. 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.

  17. 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.

  18. 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 use...

  19. 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.

  20. 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...

  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. 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...

  3. 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.

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

    PubMed

    Attar, Nuray; Turgut, Melek D

    2003-01-01

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

  5. [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

  6. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. 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.

  8. Estimation of the development possibility of the ABC/ATW fuel cycle based on LiF-BeF{sub 2} fuel salt. Part 2

    SciTech Connect

    Bychkov, A.V.; Naumov, V.S.

    1994-12-31

    The aim of the first chapter was generalization of data on solubility and equilibrium states of fission product and actinide fluorides in fluoride salt melts-solvents and fuel composition melts based on LiF-BeF{sub 2} mixture which was proposed as fuel basis for ABC/ATW facility. The second chapter is devoted to description of processes proposed for the chemical-technological complex of the ABC/ATW facility and their physico-chemical peculiarities. The complex is responsible for the removal of fission products and actinides from irradiated fuel salt.

  9. Associations between oral health behavior and anxiety about water fluoridation and motivation to establish water fluoridation in Japanese residents.

    PubMed

    Furukawa, Sayaka; Hagiwara, Yoshinori; Taguchi, Chieko; Turumoto, Akihito; Kobayashi, Seigo

    2011-09-01

    Since 1972, community water fluoridation programs have not been practiced in Japan. Risk perception among the population plays an important role in the implementation of water fluoridation programs. The oral health behavior of Japanese children has changed, especially due to recent increases among children in the use of fluoridated products and fluoride applications by dentists. The purpose of this study was to examine the associations between oral health behavior, risk perception, and the desire to implement water fluoridation among Japanese residents. We distributed a questionnaire survey (response rate: 92.8%) to mothers with children aged two or three years (n = 573). There was a correlation between anxiety and level of motivation to implement water fluoridation (Spearman coefficient: 0.355, P < 0.001). Exposure to various fluoride experiences was higher in the "not anxious" group. The motivation level was significantly higher in subjects who had a better understanding of the effectiveness of fluoride, those who used fluoride tooth paste, and those whose children received fluoride applications from dentists. We conclude that increased knowledge of and experience with fluoride might help decrease the perception of risk and increase motivation for implementing water fluoridation among the general public.

  10. Advanced heat exchanger development for molten salts

    DOE PAGES

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; ...

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet materialmore » in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.« less

  11. Advanced heat exchanger development for molten salts

    SciTech Connect

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.

  12. SALT Science Conference 2015

    NASA Astrophysics Data System (ADS)

    Buckley, David; Schroeder, Anja

    2015-06-01

    The Southern African Large Telescope (SALT) has seen great changes in the last years following the beginning of full time science operations in 2011. The three first generation instruments, namely the SALTICAM imager, the Robert Stobie Spectrograph (RSS) and its multiple modes and finally in 2014, the new High Resolution Spectrograph (HRS), have commissioned it. The SALT community now eagerly anticipate the installation and commissioning of the near-infrared arm of RSS, likely to commence in 2016. The the third "Science with SALT" conference was held at the Stellenbosch Institute of Advanced Study from 1-5 June 2015. The goals of this conference were to: -Present and discuss recent results from SALT observations; -Anticipate scientific programs that will be carried out with new SALT instrumentation such as RSS-NIR; -Provide a scientific environment in which to foster inter-institutional and inter-facility collaborations between scientists at the different SALT partners; -Provide an opportunity for students and postdocs to become more engaged in SALT science and operations; -Encourage the scientific strategic planning that will be necessary to insure an important role for SALT in an era of large astronomical facilities in the southern hemisphere such as MeerKAT, the SKA, LSST, and ALMA; -Consider options for future instrumentation and technical development of SALT; and, -Present, discuss, and engage in the SALT Collateral Benefits program led by SAAO. Conference proceedings editors: David Buckley and Anja Schroeder

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

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

  15. 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.

  16. 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.

  17. l-Leucinium fluoride monohydrate

    PubMed Central

    Zeghouan, Ouahida; Bendjeddou, Lamia; Cherouana, Aouatef; Dahaoui, Slimane; Lecomte, Claude

    2012-01-01

    The asymmetric unit of the title hydrated salt, C6H14NO2 +·F−·H2O, contains a discrete cation with a protonated amino group, a halide anion and one water mol­ecule. The crystal structure is composed of double layers parallel to (010) held together by N—H⋯O, N—H⋯F, O—H⋯F and C—H⋯F hydrogen bonds, forming a two-dimensional network, and stacked along the c axis, viz. hydro­philic layers at z = 0 and 1/2 and hydro­phobic layers at z = 1/3 and 2/3. PMID:23125742

  18. 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

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

    PubMed

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

    2014-02-19

    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 (1)H 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).

  20. 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.