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Sample records for actinium fluorides

  1. Production of high-purity radium-223 from legacy actinium-beryllium neutron sources.

    Soderquist, Chuck Z; McNamara, Bruce K; Fisher, Darrell R

    2012-07-01

    Radium-223 is a short-lived alpha-particle-emitting radionuclide with potential applications in cancer treatment. Research to develop new radiopharmaceuticals employing (223)Ra has been hindered by poor availability due to the small quantities of parent actinium-227 available world-wide. The purpose of this study was to develop innovative and cost-effective methods to obtain high-purity (223)Ra from (227)Ac. We obtained (227)Ac from two surplus actinium-beryllium neutron generators. We retrieved the actinium/beryllium buttons from the sources and dissolved them in a sulfuric-nitric acid solution. A crude actinium solid was recovered from the solution by coprecipitation with thorium fluoride, leaving beryllium in solution. The crude actinium was purified to provide about 40 milligrams of actinium nitrate using anion exchange in methanol-water-nitric acid solution. The purified actinium was then used to generate high-purity (223)Ra. We extracted (223)Ra using anion exchange in a methanol-water-nitric acid solution. After the radium was separated, actinium and thorium were then eluted from the column and dried for interim storage. This single-pass separation produces high purity, carrier-free (223)Ra product, and does not disturb the (227)Ac/(227)Th equilibrium. A high purity, carrier-free (227)Th was also obtained from the actinium using a similar anion exchange in nitric acid. These methods enable efficient production of (223)Ra for research and new alpha-emitter radiopharmaceutical development. PMID:22697483

  2. Fluoride

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

  3. A new method for the determination of low-level actinium-227 in geological samples

    We developed a new method for the determination of 227Ac in geological samples. The method uses extraction chromatographic techniques and alpha-spectrometry and is applicable for a range of natural matrices. Here we report on the procedure and results of the analysis of water (fresh and seawater) and rock samples. Water samples were acidified and rock samples underwent total dissolution via acid leaching. A DGA (N,N,N',N'-tetra-n-octyldiglycolamide) extraction chromatographic column was used for the separation of actinium. The actinium fraction was prepared for alpha spectrometric measurement via cerium fluoride micro-precipitation. Recoveries of actinium in water samples were 80 ± 8 % (number of analyses n = 14) and in rock samples 70 ± 12 % (n = 30). The minimum detectable activities (MDA) were 0.017-0.5 Bq kg-1 for both matrices. Rock sample 227Ac activities ranged from 0.17 to 8.3 Bq kg-1 and water sample activities ranged from below MDA values to 14 Bq kg-1of 227Ac. From the analysis of several standard rock and water samples with the method we found very good agreement between our results and certified values. (author)

  4. Extraction of actinium with di-(2-ethylhexyl)phosphoric acid from hydrochloric and nitric acid solutions

    The extraction of actinium with HDEHP from Cl- and NO3- systems has been investigated. It was found that extraction of actinium from HCl solutions is much better than from HNO3 solutions. Stability constants of actinium complexes Ac(X-)+2 with Cl- and NO3- ligands were determined. Our results show that the actinium formed less stable complexes with Cl- than with NO3- ligands. 5 refs., 3 figs., 1 tab. (author)

  5. Fluoridated Water

    ... Cancer Prevention Overview–for health professionals Research Fluoridated Water On This Page What is fluoride, and where is it found? What is water fluoridation? When did water fluoridation begin in the ...

  6. The sorption of polonium, actinium and protactinium onto geological materials

    This paper describes a combined experimental and modeling program of generic sorption studies to increase confidence in the performance assessment for a potential high-level radioactive waste repository in Japan. The sorption of polonium, actinium and protactinium onto geological materials has been investigated. Sorption of these radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water was studied under reducing conditions at room temperature. In addition, the sorption of actinium and protactinium was investigated at 60 C. Thermodynamic chemical modeling was carried out to aid interpretation of the results

  7. Separation of Actinium 227 from the uranium minerals

    The purpose of this work was to separate Actinium 227, whose content is 18%, from the mineral carnotite found in Gomez Chihuahua mountain range in Mexico. The mineral before processing is is pre-concentrated and passed, first through anionic exchange resins, later the eluate obtained is passed through cationic resins. The resins were 20-50 MESH QOWEX and 100-200 MESH 50 X 8-20 in some cased 200-400 MESH AG 50W-X8, 1X8 in other cases. The eluates from the ionic exchange were electrodeposited on stainless steel polished disc cathode and platinum electrode as anode; under a current ODF 10mA for 2.5 to 5 hours and of 100mA for .5 of an hour. it was possible to identify the Actinium 227 by means of its descendents, TH-227 and RA-223, through alpha spectroscopy. Due to the radiochemical purity which the electro deposits were obtained the Actinium 227 was low and was not quantitatively determined. A large majority of the members of the natural radioactive series 3 were identified and even alpha energies reported in the literature with very low percentages of non-identified emissions were observed. We conclude that a more precise study is needed concerning ionic exchange and electrodeposit to obtain an Actinium 227 of radiochemical purity. (Author)

  8. Spectroscopic and computational investigation of actinium coordination chemistry.

    Ferrier, Maryline G; Batista, Enrique R; Berg, John M; Birnbaum, Eva R; Cross, Justin N; Engle, Jonathan W; La Pierre, Henry S; Kozimor, Stosh A; Lezama Pacheco, Juan S; Stein, Benjamin W; Stieber, S Chantal E; Wilson, Justin J

    2016-01-01

    Actinium-225 is a promising isotope for targeted-α therapy. Unfortunately, progress in developing chelators for medicinal applications has been hindered by a limited understanding of actinium chemistry. This knowledge gap is primarily associated with handling actinium, as it is highly radioactive and in short supply. Hence, Ac(III) reactivity is often inferred from the lanthanides and minor actinides (that is, Am, Cm), with limited success. Here we overcome these challenges and characterize actinium in HCl solutions using X-ray absorption spectroscopy and molecular dynamics density functional theory. The Ac-Cl and Ac-OH2O distances are measured to be 2.95(3) and 2.59(3) Å, respectively. The X-ray absorption spectroscopy comparisons between Ac(III) and Am(III) in HCl solutions indicate Ac(III) coordinates more inner-sphere Cl(1-) ligands (3.2±1.1) than Am(III) (0.8±0.3). These results imply diverse reactivity for the +3 actinides and highlight the unexpected and unique Ac(III) chemical behaviour. PMID:27531582

  9. Discovery of the actinium, thorium, protactinium, and uranium isotopes

    Fry, C; Thoennessen, M

    2012-01-01

    Currently, 31 actinium, 31 thorium, 28 protactinium, and 23 uranium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  10. Radium, thorium, and actinium extraction from seawater using an improved manganese-oxide-coated fiber

    Laboratory experiments were conducted to determine the efficiency with which improved manganese-oxide-coated acrylic fibers extract radium, thorium, and actinium from seawater. Tests were made using surface seawater spiked with 227Ac, 227Th and 223Ra. For sample volumes of approximately 30 liters and flow rates up to 0.5 liters per minute, radium and actinium are removed quantitatively. Approximately 80-95% of the thorium is removed under these same conditions. (Auth.)

  11. Bottled Water and Fluoride

    ... 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, ...

  12. Metal fluorides

    Systems formed by fluorides of alkali, alkali earth, rare earth elements, yttrium, zirconium, hafnium, bismuth, antimony are investigated with the aim of preparing new fluoride materials and studying their thermodynamic and other physical and chemical properties. The respective phase diagrams are plotted. On the basis of the research fluoroberyllate glasses with rare earth additions of improved qualities (moisture resistance, crystallization resistance, resistance against radiation up to 100 Mrad) are prepared. The rho-T-x phase diagrams of the systems studied show that many compounds are sublimated congruently at certain temperatures and incongruently - above them. The existence of congruently sublimated compounds and azeotropically sublimated compositions provides for the preparation of uniform optical films. In connection with the search for new materials-luminophores and matrices of optical quantum generators - the fluoride systems of alkali metals and lanthanides are studied; the formation of binary fluorides of M3LnF6, M2LnF5, MLnF4, MLn2F7, MLn3F10 compositions is established. To search for new solid electrolytes, the solid-phase interaction of Sb-and Bi trifluorides with their oxides and alakali metal fluorides is studied. The electric conductivity of the compounds obtained is studied

  13. Production of Actinium-225 via High Energy Proton Induced Spallation of Thorium-232

    The science of cancer research is currently expanding its use of alpha particle emitting radioisotopes. Coupled with the discovery and proliferation of molecular species that seek out and attach to tumors, new therapy and diagnostics are being developed to enhance the treatment of cancer and other diseases. This latest technology is commonly referred to as Alpha Immunotherapy (AIT). Actinium-225/Bismuth-213 is a parent/daughter alpha-emitting radioisotope pair that is highly sought after because of the potential for treating numerous diseases and its ability to be chemically compatible with many known and widely used carrier molecules (such as monoclonal antibodies and proteins/peptides). Unfortunately, the worldwide supply of actinium-225 is limited to about 1,000mCi annually and most of that is currently spoken for, thus limiting the ability of this radioisotope pair to enter into research and subsequently clinical trials. The route proposed herein utilizes high energy protons to produce actinium-225 via spallation of a thorium-232 target. As part of previous R and D efforts carried out at Argonne National Laboratory recently in support of the proposed US FRIB facility, it was shown that a very effective production mechanism for actinium-225 is spallation of thorium-232 by high energy proton beams. The base-line simulation for the production rate of actinium-225 by this reaction mechanism is 8E12 atoms per second at 200 MeV proton beam energy with 50 g/cm2 thorium target and 100 kW beam power. An irradiation of one actinium-225 half-life (10 days) produces ∼100 Ci of actinium-225. For a given beam current the reaction cross section increases slightly with energy to about 400 MeV and then decreases slightly for beam energies in the several GeV regime. The object of this effort is to refine the simulations at proton beam energies of 400 MeV and above up to about 8 GeV. Once completed, the simulations will be experimentally verified using 400 MeV and 8 GeV protons

  14. Production of Actinium-225 via High Energy Proton Induced Spallation of Thorium-232

    Harvey, James T.; Nolen, Jerry; Vandergrift, George; Gomes, Itacil; Kroc, Tom; Horwitz, Phil; McAlister, Dan; Bowers, Del; Sullivan, Vivian; Greene, John

    2011-12-30

    The science of cancer research is currently expanding its use of alpha particle emitting radioisotopes. Coupled with the discovery and proliferation of molecular species that seek out and attach to tumors, new therapy and diagnostics are being developed to enhance the treatment of cancer and other diseases. This latest technology is commonly referred to as Alpha Immunotherapy (AIT). Actinium-225/Bismuth-213 is a parent/daughter alpha-emitting radioisotope pair that is highly sought after because of the potential for treating numerous diseases and its ability to be chemically compatible with many known and widely used carrier molecules (such as monoclonal antibodies and proteins/peptides). Unfortunately, the worldwide supply of actinium-225 is limited to about 1,000mCi annually and most of that is currently spoken for, thus limiting the ability of this radioisotope pair to enter into research and subsequently clinical trials. The route proposed herein utilizes high energy protons to produce actinium-225 via spallation of a thorium-232 target. As part of previous R and D efforts carried out at Argonne National Laboratory recently in support of the proposed US FRIB facility, it was shown that a very effective production mechanism for actinium-225 is spallation of thorium-232 by high energy proton beams. The base-line simulation for the production rate of actinium-225 by this reaction mechanism is 8E12 atoms per second at 200 MeV proton beam energy with 50 g/cm2 thorium target and 100 kW beam power. An irradiation of one actinium-225 half-life (10 days) produces {approx}100 Ci of actinium-225. For a given beam current the reaction cross section increases slightly with energy to about 400 MeV and then decreases slightly for beam energies in the several GeV regime. The object of this effort is to refine the simulations at proton beam energies of 400 MeV and above up to about 8 GeV. Once completed, the simulations will be experimentally verified using 400 MeV and 8 Ge

  15. Fluoridation Basics

    ... level in water is not enough to prevent tooth decay; however, some groundwater and natural springs can have ... the tooth’s surface, or enamel. Water fluoridation prevents tooth decay by providing frequent and consistent contact with low ...

  16. Neutron-Induced Fission of Actinium-227, Protactinium-231 and Neptunium-237: Mass Distribution

    Results of radiochemical studies on the mass distribution in the neutron-induced fission of actinium-227, protactinium-231 and neptunium-237 have been presented. This work has been carried out as part of a programme to determine the mass distribution in the fission of heavy elements as a function of Z and A. All irradiations have been carried out in the core of the swimming-pool type reactor APSARA with cadmium shielding wherever necessary. Relative yields of several fission product nuclides have been obtained by a method involving a comparison of the fission product activities from the respective targets with those formed from uranium-235 simultaneously irradiated. Thermal-neutron fission yields of uranium-235 have been assumed. These results indicate a predominantly asymmetric mass distribution in all the three cases, and also a distinct though small symmetric peak in the case of actinium-227. (author)

  17. How Does Fluoride Work?

    ... the mid-1940s, communities started to put more fluoride in their water supplies to protect people against tooth decay. Fluoride ... might suggest supplements — which are like vitamins containing fluoride. Just how effective is fluoridated water? Thanks to it, dentists say half of kids ...

  18. Fluoride and Dental Health

    Nikiforuk, Gordon

    1988-01-01

    Studies conducted under the widest variety of controlled conditions attest to the safety, efficacy, and cost benefits of fluoridation. A program that combines the use of systemic and topical fluoride results in maximum benefits. The author of this article reviews the metabolism of fluoride and its mechanism of action, and discusses practical modes of employing fluoride in caries prevention with special emphasis on the use of fluoride supplements for infants and young children in areas of non-...

  19. Hair as Biomarker of Fluoride Exposure in a Fluoride Endemic Area and a Low Fluoridated Area

    Parimi, Nalini; V. Viswanath; Kashyap, Bina; Patil, Pavan Uday

    2013-01-01

    Aim: The aim of the present study was to determine whether hair could be used as biomarker of fluoride exposure. Materials and Methods: The study was carried out on 30 people living in an endemically fluoridated area and a low fluoridated area. Samples of hair from the occipital were taken and subjected to fluoride analysis by a fluoride ion electrode. Results: Lower fluoride levels in water supplies correlated with lower levels of fluoride in hair and more over higher fluoride levels in wate...

  20. Analysis of the gamma spectra of the uranium, actinium, and thorium decay series

    Momeni, M.H.

    1981-09-01

    This report describes the identification of radionuclides in the uranium, actinium, and thorium series by analysis of gamma spectra in the energy range of 40 to 1400 keV. Energies and absolute efficiencies for each gamma line were measured by means of a high-resolution germanium detector and compared with those in the literature. A gamma spectroscopy method, which utilizes an on-line computer for deconvolution of spectra, search and identification of each line, and estimation of activity for each radionuclide, was used to analyze soil and uranium tailings, and ore.

  1. Analysis of the gamma spectra of the uranium, actinium, and thorium decay series

    This report describes the identification of radionuclides in the uranium, actinium, and thorium series by analysis of gamma spectra in the energy range of 40 to 1400 keV. Energies and absolute efficiencies for each gamma line were measured by means of a high-resolution germanium detector and compared with those in the literature. A gamma spectroscopy method, which utilizes an on-line computer for deconvolution of spectra, search and identification of each line, and estimation of activity for each radionuclide, was used to analyze soil and uranium tailings, and ore

  2. Effect of fluoride dentifrices on salivary fluoride levels in children.

    Paul S; Tandon S; Murthy K

    1993-01-01

    Fluoride dentifrices are well accepted for their caries preventive effects. The fluoride concentration in the oral fluids after tooth brushing with fluoride dentifrices may have an important relationship to the caries reducing capacity. The present study was aimed to clinically evaluate the salivary fluoride retention of dentifrices containing low fluoride concentration in 50 children, aged 7-9 years before, during and after the use of fluoride toothpaste. Estimation of fluoride in saliva was...

  3. Fluoride glass fiber optics

    Aggarwal, Ishwar D

    1991-01-01

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

  4. Fluoride levels and osteosarcoma

    Simmi Kharb

    2012-01-01

    Full Text Available Context: Osteosarcoma is a rare malignant bone tumor, commonly occurring in the age group of 10 to 24 years. Recent reports have indicated that there is a link between fluoride exposure and osteosarcoma. Aims: The present study was planned to analyze serum levels of fluoride in patients of osteosarcoma and fluoride content of their drinking water. Settings and Design: The present study was carried out comparing 10 patients of osteosarcoma and 10 healthy volunteers (who served as controls. Materials and Methods: Serum and drinking water fluoride levels were estimated by ion selective electrode. Statistical analysis used: The data were computed as mean ± SD and Student′s t test was applied. Results: Both, the serum and drinking water fluoride levels, were significant by higher in patients with osteosarcoma as compared to controls (P < 0.05, P < 0.001, respectively. Conclusions: These results suggest a link between fluoride exposure and osteosarcoma.

  5. Fluoride toothpastes and fluoride mouthrinses for home use

    Andrew Rugg-Gunn; Jolan Bánóczy

    2013-01-01

    Objective. To provide a brief commentary review of fluoride-containing toothpastes and mouthrinses with emphasis on their use at home. Toothpastes and mouthrinses are just two of many ways of providing fluoride for the prevention of dental caries. The first investigations into incorporating fluoride into toothpastes and mouthrinses were reported in the middle 1940s. Unlike water fluoridation (which is ‘automatic fluoridation’), fluoride-containing toothpastes and fluoride-containing mouthrins...

  6. Fluoride and Oral Health.

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

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature. PMID:27352462

  7. Fluoride varnishes and enamel caries

    De Bruyn, Hugo

    1987-01-01

    Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical applications. Recently the importance of small amounts of fluoride in caries prevention and remineralization has been stressed and the importance of large arnounts of fluoride acquired in the teeth is ...

  8. In-source laser spectroscopy developments at TRILIS—towards spectroscopy on actinium and scandium

    Resonance Ionization Laser Ion Sources (RILIS) have become a versatile tool for production and study of exotic nuclides at Isotope Separator On-Line (ISOL) facilities such as ISAC at TRIUMF. The recent development and addition of a grating tuned spectroscopy laser to the TRIUMF RILIS solid state laser system allows for wide range spectral scans to investigate atomic structures on short lived isotopes, e.g., those from the element actinium, produced in uranium targets at ISAC. In addition, development of new and improved laser ionization schemes for rare isotope production at ISAC is ongoing. Here spectroscopic studies on bound states, Rydberg states and autoionizing (AI) resonances on scandium using the existing off-line capabilities are reported. These results allowed to identify a suitable ionization scheme for scandium via excitation into an autoionizing state at 58,104 cm − 1 which has subsequently been used for ionization of on-line produced exotic scandium isotopes.

  9. Fluoride and Water (For Parents)

    ... Story" 5 Things to Know About Zika & Pregnancy Fluoride and Water KidsHealth > For Parents > Fluoride and Water Print A ... thirds of 16- to 19-year-olds continue Fluoride and the Water Supply For more than 60 years, water fluoridation ...

  10. The cariostatic mechanisms of fluoride

    Kata Rošin-Grget; Kristina Peroš; Ivana Šutej; Krešimir Bašić

    2013-01-01

    This article discusses the possible cariostatic mechanisms of the action of fluoride. In the past, fluoride inhibition of caries was ascribed to reduced solubility of enamel due to incorporation of fluoride (F–) into the enamel minerals. The present evidence from clinical and laboratory studies suggests that the caries-preventive mode of action of fluoride is mainly topical. There is convincing evidence that fluoride has a major effect on demineralisation and remineralisation of dental hard t...

  11. Fluoride in diet

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

  12. Fluoride toothpastes and fluoride mouthrinses for home use

    Andrew Rugg-Gunn

    2013-11-01

    Full Text Available Objective. To provide a brief commentary review of fluoride-containing toothpastes and mouthrinses with emphasis on their use at home. Toothpastes and mouthrinses are just two of many ways of providing fluoride for the prevention of dental caries. The first investigations into incorporating fluoride into toothpastes and mouthrinses were reported in the middle 1940s. Unlike water fluoridation (which is ‘automatic fluoridation’, fluoride-containing toothpastes and fluoride-containing mouthrinses are, primarily, for home use and need to be purchased by the individual. By the 1960s, research indicated that fluoride could be successfully incorporated into toothpastes and clinical trials demonstrated their effectiveness. By the end of the 1970s, almost all toothpastes contained fluoride. The widespread use of fluoride-containing toothpastes is thought to be the main reason for much improved oral health in many countries. Of the many fluoride compounds investigated, sodium fluoride, with a compatible abrasive, is the most popular, although amine fluorides are used widely in Europe. The situation is similar for mouthrinses. Concentrations of fluoride (F, commonly found, are 1500 ppm (1500 μg F/g for toothpastes and 225 ppm (225 μg F/ml for mouthrinse. Several systematic reviews have concluded that fluoride-containing toothpastes and mouthrinses are effective, and that there is added benefit from their use with other fluoride delivery methods such as water fluoridation. Guidelines for the appropriate use of fluoride toothpastes and mouthrinses are available in many countries.Conclusion. Fluoride toothpastes and mouthrinses have been developed and extensive testing has demonstrated that they are effective and their use should be encouraged.

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

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

  14. Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

    Raeder, S.; Bastin, B.; Block, M.; Creemers, P.; Delahaye, P.; Ferrer, R.; Fléchard, X.; Franchoo, S.; Ghys, L.; Gaffney, L. P.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Luton, F.; Moore, I. D.; Martinez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

    2016-06-01

    To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

  15. Fluoridated elastomers: in vivo versus in vitro fluoride release

    Tinsley, D.; O'Dwyer, J. J.; Benson, P.E.

    2003-01-01

    OBJECTIVES: To compare (i) the in vivo release of fluoride from fluoridated elastomers to the in vitro release, and (ii) the residual fluoride content of the elastomers after 1 week in the mouth with and without fluoride toothpaste and mouthrinse. DESIGN: A prospective, longitudinal, cross-over study. Subjects and method: Six subjects were recruited by poster to take part in the study. Each subject had one premolar in each quadrant to which a bracket could be fixed and exemplar...

  16. Fluoride retention by kaolin clay

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

    1997-01-01

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

  17. Fluoride Uptake Level of the Enamel by a Fluoride Varnish and a Fluoride Gel (APF)

    Navabi B; Ansari G.; Khan Z; Kheirieh P.; Najafi B.

    2011-01-01

    Statement of Problem: Various forms of fluoride-contained products are used to increase the resistance of the tooth against caries for preventive purposes. Furthermore, studies demonstrated higher fluoride uptake with varnish and gel among the wide range of products.Purpose: This study compared fluoride uptake of Duraflor® varnish (Practicon Dent, USA) with fluoride gel (APF, Sultan®), used on the enamel surface of the intact teeth.Materials and Method: In this experimental in-vitro study, 2...

  18. Other Fluoride Products

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

  19. Salt fluoridation and oral health

    Thomas M. Marthaler

    2013-11-01

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

  20. Water fluoridation and oral health

    Máiréad Antoinette Harding

    2013-11-01

    Full Text Available 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. Conclusion: 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.

  1. Health Effects Associated with Water Fluoridation.

    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)

  2. Fluoride and dental caries

    Camilleri, George E.

    1998-01-01

    Fluorine was probably discovered by the chemist Scheele in 1771, and eventually isolated in 1886 by Moissan. Its presence in bones and teeth was initially disputed but eventually confirmed in the middle of the eighteenth century. In this article the author discusses the few epidemiological studies which confirm the relationship between fluoride concentration in drinking water, mottled enamel and the incidence of dental caries and also describes the Maltese scene in regards the caries level in...

  3. Fluoride in dental erosion

    Magalhães, A C; Wiegand, A.; Rios, D.; Buzalaf, M.A.R.; Lussi, A.

    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 l...

  4. Strontium-90 fluoride data sheet

    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 90SrF2-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977

  5. Fluoride remediation using floating macrophytes

    Naba Kumar Mondal; Ria Bhaumik; Uttiya Dey; Kartick Chandra Pal; Chittaranjan Das; Anindita Maitra; Jayanta Kumar Datta

    2014-01-01

    Six aquatic macrophytes, such as Pistia stratiotes, Ceratophyllum demersum, Nymphoides indica, Lemna major, Azolla pinnata,and Eichhornia crassipes were considered for remove fluoride from aqueous solution. Five different concentrations (10, 30, 50, and 100 ppm) of fluoride solution were taken in 1 L plastic container. Fixed weight (20 g) of macrophytes along with 500 ml fluoride solution was taken in each plastic container for 72 hours observation. Results demonstrated all the macrophytes sh...

  6. Fluoride Rinses, Gels and Foams

    Twetman, Svante; Keller, Mette K

    2016-01-01

    electronic search for literature published in English between 2003 and 2014. The included papers were assessed for their risk of bias and the results were narratively synthesized due to study heterogeneity. The quality of evidence was expressed according to GRADE. RESULTS: A total of 19 papers were included......, previously established in systematic reviews. The lack of clinical trials free from bias is, however, still a concern, especially for fluoride mouth rinses and fluoride foam. There is also a scientific knowledge gap on the benefit and optimal use of these fluoride supplements in combination with daily tooth...... brushing with fluoride toothpaste....

  7. Private Well Water and Fluoride

    ... it is the responsibility of the homeowner to know and understand the quality of the water from their well. The U.S. ... or area. Additional information on testing well water quality in private wells ... do I need to know about fluoride and groundwater from a well? Fluoride ...

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

    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…

  9. 49 CFR 173.163 - Hydrogen fluoride.

    2010-10-01

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

  10. Molten fluoride fuel salt chemistry

    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

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

    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 u...

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

    Souza, Daniela Correia Cavalcante; Marisa MALTZ; Lina Naomi HASHIZUME

    2014-01-01

    This single-blind, randomized, crossover study aimed at assessing the long-term fluoride concentrations in saliva and in dental biofilm after different home-use fluoride treatments. The study volunteers (n = 38) were residents of an area with fluoridated drinking water. They were administered four treatments, each of which lasted for one week: twice-daily placebo dentifrice, twice-daily fluoride dentifrice, twice-daily fluoride dentifrice and once-daily fluoride mouthrinse, and thrice-daily f...

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

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

    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 DuraphatTM. MATERIAL AND METHODS: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, s...

  14. Fluoride glass: Crystallization, surface tension

    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. Chronic Fluoride Toxicity: Dental Fluorosis

    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 enam...

  16. Method of aluminium fluoride manufacture

    The manufacture of aluminium fluoride is based on waste processing in uranium hexafluoride conversion to uranium oxides within the fuel cycle. The conversion is the stoichiometric conversion of uranium hexafluoride with aluminium nitrate to uranyl nitrate. This is extracted from the water phase by phosphoric acid trialkyl ester to an organic solvent and further processed. The discharge water phase is solidified by evaporation to solid aluminium fluoride and nitric acid. (M.S.)

  17. The fluoride content of bottled drinking waters.

    Toumba, K J; Levy, S; Curzon, M E

    1994-04-01

    Sales of bottled drinking waters in the United Kingdom have tripled over the last 5 years. The fluoride content of 12 bottled waters purchased from two Leeds supermarkets was determined by both the direct and acid diffusion methods and found to vary from 0.10-0.80 mg/l fluoride (ie ppm fluoride). This article shows that bottled drinking waters contain differing concentrations of fluoride. There is no apparent difference between the direct and acid diffusion methods for the determination of fluoride concentrations of drinking waters. The manufacturers' labelling of fluoride concentrations are mainly inaccurate. Dentists should be aware of the fluoride concentrations of the drinking water of their child patients, be they municipal or bottled drinking water, when prescribing fluoride supplements. Also, some parents are using bottled waters to prepare baby milk formulations which themselves may contain high levels of fluoride and subject their children to the risk of dental fluorosis. PMID:8186036

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

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

  19. Industrial fluoride pollution. Chronic fluoride poisoning in Cornwall Island cattle.

    Krook, L; Maylin, G A

    1979-04-01

    An aluminum plant on the south bank of the St. Lawrence river, southwest of Cornwall Island, Ontario, Canada, has emitted 0.816 metric tons of fluoride daily since 1973; considerably higher amounts were emitted from 1959 to 1973. The plant has been designated as the "major source of fluoride emissions impacting on Cornwall Island." Chronic fluoride poisoning in Cornwall island cattle was manifested clinically by stunted growth and dental fluorosis to a degree of severe interference with drinking and mastication. Cows died at or were slaughtered after the third pregnancy. The deterioration of cows did not allow further pregnancies. Fluoride concentrations in ash of biopsied coccygeal vertebrae increased significantly with age and were dependent on distance from and direction to the aluminum plant. Fluoride in bone ash of a 7-month old-fetus exceeded 500 ppm; fluoride thus was passed transplacentally. Analyses of fluoride in ash of bones obtained at necropsy of cattle from 4 months of age to 4 to 5 years of age showed increased amounts with age. Cancellous bone retained far higher amounts than cortical bone, a reflection of the normally higher metabolic rate of cancellous bone. Concentrations exceeding 10,000 ppm fluoride were recorded in cancellous bone of a 4-to 5-year-old cow. The target cells for fluoride in chronic fluorosis were shown to be the ameloblasts, the dental pulp cells and the odontoblasts and, in bone, primarily the resorbing osteocytes and also the osteoblasts. Atrophy and necrosis of the ameloblasts were responsible for enamel defects. The existing enamel showed brown discoloration from fluoride deposits. The pulp cells underwent fibrous and osseous metaplasia and necrosis of the ectopic bone occurred. The odontoblasts were atrophic and the dentin showed brown discoloration. The resorbing osteocytes were inactive and osteosclerosis resulted. This was especially pronounced in areas of normally great apposition, i.e. in the metaphyses. The epiphyseal

  20. Fluoridering af drikkevandet i Danmark?

    Arvin, Erik; Spliid, Henrik; Bruvo, M.; Bardow, A.; Ekstrand, K.

    2010-01-01

    Første gang sammenhængen mellem caries (huller i tænderne) og fluoridindholdet i drikkevand blev diskuteret i vandværkskredse i Danmark var ved årsmødet i 1958. Her blev det oplyst, at fluorid i drikkevand beskytter mod caries, men man konstaterede også, at der nok ikke var stemning for fluorid......-tilsætning til drikkevandet (fluoridering). Siden da er emnet ikke taget op. Formålet med dette indlæg er at besvare spørgsmålene: 1. Er der behov for fluoridering af drikkevandet i Danmark? 2. Er der alternativer? Hvordan påvirker blødgøring af vand og andre vandbehandlingsmetoder dental caries hos børn og unge......? Som baggrund herfor vil vi redegøre for resultaterne af et netop afsluttet studium af sammenhængen mellem caries og drikkevandets sammensætning, specielt m.h.t. luoridindholdet og vandets calciumindhold (hårdhed). Undersøgelsen bekræfter, at fluorid i drikkevand i væsentlig grad beskytter mod caries...

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

    Uranium hexafluoride (UF6) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO2F2) and hydrogen fluoride (HF). Uranium compounds such as UF6 and UO2F2 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 UF6, UO2F2, and HF. 4 refs., 2 figs., 5 tabs

  2. IMPACT OF FLUORIDE ON DENTAL HEALTH QUALITY

    Medjedovic, Eida; Medjedovic, Senad; Deljo, Dervis; Sukalo, Aziz

    2015-01-01

    Introduction: Fluoride is natural element that strengthens teeth and prevents their decay. Experts believe that the best way to prevent cavities is the use of fluoride from multiple sources. Studies even show that in some cases, fluoride can stop already started damage of the teeth. In children younger than 6 years fluoride is incorporated into the enamel of permanent teeth, making the teeth more resistant to the action of bacterial and acids in food. Goal: The aim of this study is to determi...

  3. Alimentary fluoride intake in preschool children

    Lencova Erika; Ivancakova Romana; Oganessian Edgar; Broukal Zdenek

    2011-01-01

    Abstract 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...

  4. Molten fluorides for nuclear applications

    Sylvie. Delpech

    2010-12-01

    Full Text Available The importance of pyrochemistry is being increasingly acknowledged and becomes unavoidable in the nuclear field. Molten salts may be used for fuel processing and spent fuel recycling, for heat transfer, as a homogeneous fuel and as a breeder material in fusion systems. Fluorides that are stable at high temperature and under high neutron flux are especially promising. Analysis of several field cases reveals that corrosion in molten fluorides is essentially due to the oxidation of metals by uranium fluoride and/or oxidizing impurities. The thermodynamics of this process are discussed with an emphasis on understanding the mass transfer in the systems, selecting appropriate metallic materials and designing effective purification methods.

  5. Fluoride: its role in dentistry

    Livia Maria Andaló Tenuta

    2010-01-01

    Full Text Available In spite of decades of research on fluoride and the recognition of its role as the cornerstone of dental caries reduction in the last fifty years, questions still arise on its use at community, self-applied and professional application levels. Which method of fluoride delivery should be used? How and when should it be used? How can its benefits be maximized and still reduce the risks associated with its use? These are only some of the challenging questions facing us daily. The aim of this paper is to present scientific background to understand the importance of each method of fluoride use considering the current caries epidemiological scenario, and to discuss how individual or combined methods can be used based on the best evidence available.

  6. Fluoride Uptake Level of the Enamel by a Fluoride Varnish and a Fluoride Gel (APF

    Navabi B.

    2011-07-01

    Full Text Available Statement of Problem: Various forms of fluoride-contained products are used to increase the resistance of the tooth against caries for preventive purposes. Furthermore, studies demonstrated higher fluoride uptake with varnish and gel among the wide range of products.Purpose: This study compared fluoride uptake of Duraflor® varnish (Practicon Dent, USA with fluoride gel (APF, Sultan®, used on the enamel surface of the intact teeth.Materials and Method: In this experimental in-vitro study, 20 intact pre-molar teeth extracted for orthodontic purposes were randomly assigned to two groups of 10 teeth. The teeth were sectioned into two mesial and distal halves as the control and experimental sides. Defined semi-circular areas on the enamel surface of the experimental halves were treated with gel or varnish for 1 hour. The sample halves were stored in artificial saliva for 24 hours at 37°c, etched for 30 seconds by 0.5 M perchloric acid, and washed by 0.2 m KOH after each etching process. Biopsies of the samples were obtained by Acid Etch Enamel Biopsy technique and the fluoride and calcium concentrations were calculated by potentiometer and spectrophotometer, respectively. Kolmogorov-smirnov, Paired t-test and Student t- test were used for statistical analyses.Results: The results demonstrated an increase in the enamel fluoride content after exposure of the teeth to both Duraflor® varnish and APF gel (Sultan®. The results of the paired t-test revealed significant differences between the experimental and control halves in both groups (varnish: p =0.002, gel: p =0.039. The fluoride uptake value in varnish and gel groups was 2069.78 ppm and 1050.99 ppm, respectively. The student t-test showed a statistically significant difference ( p =0.01.Conclusion: Both APF gel and Duraflor® varnish increased the fluoride content of the tooth enamel after application, although Duraflor® varnish had a higher fluoride uptake level than APF gel.

  7. Effect of fluoride on Treponema denticola.

    Hughes, C A; Yotis, W W

    1986-01-01

    The effect of fluoride on the growth of Treponema denticola was studied. Fluoride, at a concentration of 20 micrograms/ml, was found to suppress the growth of all three strains tested. Growth was completely inhibited by 40 micrograms of fluoride per ml.

  8. Fluoride in African groundwater: Occurrence and mitigation

    Vasak, S.; Griffioen, J.; Feenstra, L.

    2010-01-01

    Fluoride in groundwater has both natural and anthropogenic sources. Fluoride bearing minerals, volcanic gases and various industrial and agricultural activities can contribute to high concentrations. High intake of fluoride from drinking water is the main cause of fluorosis and may lead to many othe

  9. Ultraviolet transmission of fluoride glasses

    In recent years there has been a great deal of interest in infrared-transmitting materials. However, with the commercial interest in excimer lasers and collection and utilization of solar energy, there is an increased interest in UV transmitting materials. In the absence of impurities, it has been observed that fluoride glasses are potentially very good UV transmitters. This paper reports the effects of intense UV radiation on fluoride glasses of various composition and on the status of dopants in those glasses. Possible limitations for these materials as UV transmission media are discussed

  10. Groundwater seepage from the Ranger uranium mine tailings dam: radioisotopes of radium, thorium and actinium. Supervising Scientist report 106

    Monitoring of bores near the Ranger uranium mine tailings dam has revealed deterioration in water quality in several bores since 1983. In a group of bores to the north of the dam, increases have been observed of up to 500 times for sulphate concentrations and of up to 5 times for 226Ra concentrations. Results are presented here of measurements of members of the uranium, thorium and actinium decay series in borewater samples collected between 1985 and 1993. In particular, measurements of all four naturally-occurring radium isotopes have been used in an investigation of the mechanism of radium concentration changes. For the most seepage-affected bores the major findings of the study include: 228Ra/226Ra 223Ra /226Ra and 224Ra/228Ra ratios all increased over the course of the study; barium concentrations show high seasonal variability, being lower in November than May, but strontium concentrations show a steady increase with time. Calculations show that the groundwater is probably saturated with respect to barite but not with respect to celestite or anglesite; sulphide concentrations are low in comparison with sulphate, and are higher in November than in May; and 227Ac concentrations have increased with time, but do not account for the high 223Ra/226Ra ratios. It is concluded on the basis of these observations that increases in Ra isotope concentrations observed in a number of seepage-affected bores arise from increases in salinity leading to desorption of radium from adsorption sites in the vicinity of the bore rather by direct transport of radium from the tailings. Increased salinity is also causing the observed increases in 227Ac and strontium concentrations, while formation of a barite solid phase in the groundwater is causing the removal of some radium from solution. This is the cause of the increasing radium isotope ratios noted above

  11. Fluoride remediation using floating macrophytes

    Naba Kumar Mondal

    2014-04-01

    Full Text Available Six aquatic macrophytes, such as Pistia stratiotes, Ceratophyllum demersum, Nymphoides indica, Lemna major, Azolla pinnata,and Eichhornia crassipes were considered for remove fluoride from aqueous solution. Five different concentrations (10, 30, 50, and 100 ppm of fluoride solution were taken in 1 L plastic container. Fixed weight (20 g of macrophytes along with 500 ml fluoride solution was taken in each plastic container for 72 hours observation. Results demonstrated all the macrophytes show highest fluoride removal during 24 h to 48 h, but after 72 h their efficiency reduced drastically. The species N. indica showed better removal efficiency than other experimental macrophytes. In general, pigment measurement data indicated higher concentration at 72 h. However, Pistia sp. showed higher concentration of pigmentation at intermediate time interval (48 h. Higher level of dry weight to fresh weight ratio was recorded for L. major and A. pinnata at all concentrations, excepting at 10 ppm. In addition, all macrophytes showed lower RGR at higher concentration. Isotherm study indicated that macrophyte C. demersum is a good fitted with Freundlich and Langmuir isotherm whereas L. major with Langmuir isotherm during 24 hours.

  12. Global affordability of fluoride toothpaste

    Holmgren Christopher J

    2008-06-01

    Full Text Available Abstract 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.

  13. Alimentary fluoride intake in preschool children

    Lencova Erika

    2011-10-01

    Full Text Available Abstract 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

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

    Daniela Correia Cavalcante SOUZA

    2014-08-01

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

  15. Computer simulation of superionic fluorides

    Castiglione, M

    2000-01-01

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

  16. Discovery of Interstellar Hydrogen Fluoride

    Neufeld, D A; Schilke, P; Phillips, T G; 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 (LWS) 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 3E-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 ~ 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...

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

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

    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 met...

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

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

    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 topica...

  19. Comparison of salivary fluoride levels following use of dentifrices containing different concentrations of fluoride

    Nagpal D; Damle S

    2007-01-01

    Many industrialized countries have reported a decline in caries prevalence over the past few decades. These reductions have been related to the regular use of fluoride dentifrices. Fluoride dentifrices are the most cost-effective and efficient means of caries prevention. However, there have been concerns regarding the risk of fluorosis in children due to the ingestion of dentifrices. This has led to the use of dentifrices with low concentration of fluoride. Salivary fluoride levels after toot...

  20. Ruthenium olefin metathesis catalysts containing fluoride

    Guidone, Stefano; Songis, Olivier; Falivene, Laura; Nahra, Fady; Slawin, Alexandra Martha Zoya; Jacobsen, Heiko; Cavallo, Luigi; Cazin, Catherine S. J.

    2015-01-01

    The authors gratefully acknowledge the EC through the 7th framework program (grant CP-FP 211468-2 EUMET), the Royal Society (University Research Fellowship to CSJC) for financial support. The reaction of the ruthenium complex cis-Caz-1 with silver fluoride affords the first example of an active olefin metathesis pre-catalyst containing fluoride ligands. The cis geometry of the precursor complex is key to the successful fluoride exchange reaction. Computational studies highlight the stabili...

  1. Estuarine response of fluoride - Investigations in Azhikode Estuary

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

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

  2. Fluoride bioavailability in saliva and plaque

    Naumova Ella A; Kuehnl Phillip; Hertenstein Philipp; Markovic Ljubisa; Jordan Rainer A; Gaengler Peter; Arnold Wolfgang H

    2012-01-01

    Abstract 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 ...

  3. Gramicidin D enhances the antibacterial activity of fluoride

    Nelson1, James W.; ZHOU, ZHIYUAN; Breaker, Ronald R.

    2014-01-01

    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 B. subtilis and that the antibacterial activity of this compound...

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

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

    2014-01-01

    Previous reports found that some fluoride-containing dentifrices do not release effective concentrations of fluoride during brushing. Failure to release fluoride can be due to dentifrice matrix components that interfere with the solubilization of the fluoride salts during brushing. A new generation of dentifrices has the capability to precipitate beneficial fluoride salts during tooth brushing. Therefore, a method that assesses the potentially available fluoride during the 1-minute brushing i...

  5. Fluoride in cerebrospinal fluid of patients with fluorosis.

    Hu, Y H; Wu, S S

    1988-01-01

    The CSF fluoride level of individuals drinking water with normal fluoride content and of patients with endemic fluorosis were studied. For the purpose of studying the relationship between the dynamic equilibrium of the CSF fluoride and other body fluids, urine and blood fluoride were examined simultaneously. Fluoride was revealed in every CSF sample of the control group and its mean value was lower than that of the blood. The CSF fluoride concentration of patients with fluorosis was slightly ...

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

    Kelly Polido Kaneshiro Olympio

    2009-06-01

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

  7. HOUSEHOLD PURIFICATION OF FLUORIDE CONTAMINATED MAGADI (TRONA)

    Nielsen, Joan Maj; Dahi, Elian

    1997-01-01

    Purification of fluoride contaminated magadi is studied using bone char sorption and calcium precipitation. The bone char treatment is found to be workable both in columns and in batches where the magadi is dissolved in water prior to treatment. The concentrations in the solutions were 89 g magadi...... treatment method. A procedure for purification of fluoride contaminated magadi at household level is described....

  8. Growth of hollow nickel fluoride whiskers

    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-μm side. The wall thickness is 85 ± 20 μm.

  9. Reaction of uranyl fluoride with sodium fluoride in aqueous solution

    The formation of complex uranyl fluorides in the system NaF-VO2F2-H2O has been studied and some of their properties have been investigated. It has been shown that, depending on the mole ratio of the components (from 0.5:1 to 5:1), fluorouranylates Na(VO2)2F5x4H2O, Na3(VO2)2F7x2H2O, and Na3VO2F5 are formed. Infrared spectra have demonstrated that H2O molecules are not coordinated by the central atom. Dehydration of hydrated complexes proceeds in two stages. Non-aqueous Na3(VO2)2F5 melts at 540 deg C. The synthesized complexes are studied by X-ray structural analysis. The compositions of complex uranyl fluorides formed in the systems MF-VO2F2-H2O (M=Na,K,Rb,Cs,NH4, CN3H6) have been compared

  10. Determination of fluoride content in drinking water and tea infusions using fluoride ion selective electrode

    Rajković Miloš B.

    2007-01-01

    Full Text Available Potentiometric analysis of fluoride content (as F- ion in solutions by using fluoride ion-selective electrode is simple, reliable and cheap. Very small concentrations of fluoride-ions (to 10-6 mol/dm3 can be determined by fluoride selective electrode, with regulation of ion strength of a solution and control of concentration of hydroxide ions and interfering ions of metals. The influence of pH and complexing ions of metals can be successfully regulated by the TISAB solution and by preserving pH value in the range from 5.00 to 7.00. The content of fluorides in the samples can be determined by the method of direct potentiometer, and in the case of very low concentration by standard addition method. In this paper it was analyzed the determination of fluoride ions concentration in bottled mineral waters and water from Belgrade plumbing in two Belgrade districts (Palilula and Novi Beograd and in tea, by using the fluoride selective electrode. It was determined that the content of fluoride ions in bottled mineral water significantly differs from values given on declaration, and that content of fluoride ions varies over a period of time. The content of fluoride ions in water from plumbing in two Belgrade districts at the time of analysis was significantly increased and exceeded values given in Regulation for drinking water quality. The received results from the analysis of fluorides in teas show that fluorides exist in teas in different concentrations. There are also differences between the same kinds of tea, which is noted with mint (Mentha piperitae folium, as a consequence of differences between soils where it was planted. As taking of fluorides, according to World Health Organisation recommendation (WHO, is limited in the range from 2 to 4 mg per day, it is necessary to give the content of fluorides on all products that are used in human consumption.

  11. Niobium electrodeposition from molten fluorides

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

  12. Manufacture and properties of fluoride cement

    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

  13. Determination of Fluoride in Different Toothpaste Formulations

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

  14. Substoichiometric precipitation of fluoride with lanthanum

    The substoichiometric precipitation of fluoride with lanthanum was studied by using 18F and 140La tracers. It was found that fluoride could be precipitated substoichiometrically with lanthanum and the reaction ratio between fluoride and lanthanum was 3:1. The pH range at which fluoride can be separated subsotichiometrically with lanthanum is between 2 and 8. Barium and indium interfere in the precipitation of fluoride, but sodium, copper and manganese do not. Fluorosilicate can also be precipitated subsotichiometrically by using lanthanum as a precipitant and the reaction ratio between fluorosilicate and lanthanum was 1:2. This separation was applied for the determination of oxygen in silicon crystals. The concentration of oxygen measured in some silicon crystals was between 5 and 27 ppm and was in good agreement with those by non-destructive method and infrared spectrophotometry. (author)

  15. Recent advancements in fluoride: A systematic review

    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

  16. Method of treating fluoride contaminated wastes

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

    1988-04-05

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

  17. Fluoride Importance in Controlling Caries and Fluorosis

    Gaurav Solanki

    2012-04-01

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

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

    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. PMID:26188404

  19. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly(vinyl fluoride) resins. 175.270 Section 175... Substances for Use as Components of Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride... the purpose of this section, poly(vinyl fluoride) resins consist of basic resins produced by...

  20. Fluoride Programs in the School Setting: Preventive Dental Health.

    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)

  1. Evaluation of toxic action of fluorides on agricultural plants

    V. N. Grishko

    2007-03-01

    Full Text Available The toxicity of potassium fluoride, sodium fluoride and ammonium fluoride for pea, maize, oat and onion was studied. It was found that the level of the toxic influence had grown with increase of fluoride concentration in the media of growth (from 5 to 100 mg of F–/l. By increase of the toxic influence the agricultural crops are disposed in the following row: oat < onion < maize < pea. Ammonium fluoride demonstrates lesser toxicity, than potassium and sodium fluorides. Under low concentrations of fluoride compounds (5 and 10 mg of F–/l stimulation of roots growth is noted only for the oat.

  2. Fluoride

    ... is sometimes prescribed for other uses; ask your doctor or pharmacist for more information. ... on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. ...

  3. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Richard Sauerheber

    2013-01-01

    Full Text Available 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.

  4. New Insight on the Response of Bacteria to Fluoride

    Breaker, R R

    2012-01-01

    Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biolog...

  5. Current Concept on the Anticaries Fluoride Mechanism of the Action

    Rošin-Grget, K.; Linčir, I.

    2001-01-01

    The paper discusses a possible new concept of the role of fluoride and its mechanism of action in caries prevention. In the past fluoride inhibition of caries was ascribed to reduced solubility due to incorporation of fluoride (F–) into the enamel minerals (firmly bound fluoride or fluorapatite). Based on the new findings, it appears that fluoride, either released into or present in the fluid phase bathing the hard tissue, is more important for the reduction of caries developme...

  6. Topical fluoride as a cause of dental fluorosis in children

    Wong, MCM; Lo, ECM; Glenny, AM; Tsang, BWK; Worthington, HV; Marinho, VCC

    2009-01-01

    BACKGROUND: For many years, topical use of fluorides has gained greater popularity than systemic use of fluorides. A possible adverse effect associated with the use of topical fluoride is the development of dental fluorosis due to the ingestion of excessive fluoride by young children with developing teeth. OBJECTIVES: To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis. SEARCH STRATEGY: Electronic search of the Cochra...

  7. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Richard Sauerheber

    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 ...

  8. Technology of obtaining of cryolite and aluminium fluoride from alumina- and fluoride containing wastes of aluminium production

    This article is devoted to technology of obtaining of cryolite and aluminium fluoride from alumina- and fluoride containing wastes of aluminium production. Thus, the investigations on elaboration of technology of obtaining of cryolite and aluminium fluoride from alumina- and fluoride containing wastes of aluminium production by means of sulfuric acid decomposition method are carried out. The optimal parameters of technological processes are found. The physicochemical analysis of fluoride containing wastes is conducted. The flowsheet of obtaining of cryolite, aluminium fluoride and alumina from alumina- and fluoride containing wastes is presented.

  9. The Adsorption of Hydrogen Fluoride and Fluoride Ion on a Water Treatment Sludge

    Oh, Taek-Keun; Saeki, Kazutoshi

    2009-01-01

    The hydrogen fluoride (HF) and fluoride ion (F^-) adsorption potentials of a water treatment sludge were investigated in a batch mode as a function of pH, contact time, initial fluoride concentrations, and other co-existing anions. The maximum removal of total fluoride was apparently observed at pH 5.1, whereas HF or F^- adsorptions showed nearly 100% in pH range from 2.2 to 4.3. The HF or F^- adsorption by the water treatment sludge has occurred rapidly during the initial 5.60 min and therea...

  10. Determination of fluoride content in drinking water and tea infusions using fluoride ion selective electrode

    Rajković Miloš B.; Novaković Ivana D.

    2007-01-01

    Potentiometric analysis of fluoride content (as F- ion) in solutions by using fluoride ion-selective electrode is simple, reliable and cheap. Very small concentrations of fluoride-ions (to 10-6 mol/dm3) can be determined by fluoride selective electrode, with regulation of ion strength of a solution and control of concentration of hydroxide ions and interfering ions of metals. The influence of pH and complexing ions of metals can be successfully regulated by the TISAB solution and by preservin...

  11. Study of fluoride corrosion of nickel alloys

    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.

  12. Recent advancements in fluoride: A systematic review

    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 f...

  13. Fluoride removal from water by nano filtration

    As any oligo element, fluoride is necessary and beneficial for human health to low concentrations, but an excess amount of fluoride ions in drinking water has been known to cause undesirable effects, especially tooth and bones fluoro sis. The maximum acceptable concentration of fluoride in drinking water was fixed by the World Health Organization according to the climate in the range of 1 mg.L-1 to 1,2 mg.L-1. Many methods have been used to remove fluoride from water such as precipitation, adsorption, electrocoagulation and membrane processes. Technologies using membrane processes are being used in many applications, particularly for brackish water desalination. Nano filtration seems to be the best process for a good selective defluorination of fluorinated waters. The main objective of this work was to investigate the retention of fluoride anions by nano filtration. The first part of this study deals with the characterisation of the NF HL2514TF membrane. The influence of various experimental parameters such as initial fluoride content, feed pressure, permeate flux, ionic strength, type of cation associated to fluoride and pH were studied in the second part. Results show that the retention order for the salts tested was TR(Na2SO4) > TR(CaCl2) > TR(NaCl), showing a retention sequence inversely proportional to the salt diffusion coefficients in water. It was also shown that charge effects could not be neglected, and a titration experiments confirmed that the NF membrane carry a surplus of negatively charged groups. Fluoride retention exceeds 60 pour cent, and increases with increasing concentration, where the rejection mechanism is related to the dielectric effects. Speigler-Kedem model was applied to experimental results in the aim to determine phenomenological parametersσand Ps respectively, the reflexion coefficient of the membrane and the solute permeability of ions. The convective and diffusive parts of the mass transfer were quantified with predominance of the

  14. Debating Water Fluoridation Before Dr. Strangelove.

    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. PMID:26066938

  15. Well Waters Fluoride in Enugu, Nigeria

    EI Ugwuja

    2012-03-01

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

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

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

    2011-01-01

    Thermal water samples from Yellowstone National Park (YNP) have a wide range of pH (1-10), temperature, and high concentrations of fluoride (up to 50mg/l). High fluoride concentrations are found in waters with field pH higher than 6 (except those in Crater Hills) and temperatures higher than 50??C based on data from more than 750 water samples covering most thermal areas in YNP from 1975 to 2008. In this study, more than 140 water samples from YNP collected in 2006-2009 were analyzed for free-fluoride activity by ion-selective electrode (ISE) method as an independent check on the reliability of fluoride speciation calculations. The free to total fluoride concentration ratio ranged from 99% at high pH. The wide range in fluoride activity can be explained by strong complexing with H+ and Al3+ under acidic conditions and lack of complexing under basic conditions. Differences between the free-fluoride activities calculated with the WATEQ4F code and those measured by ISE were within 0.3-30% for more than 90% of samples at or above 10-6 molar, providing corroboration for chemical speciation models for a wide range of pH and chemistry of YNP thermal waters. Calculated speciation results show that free fluoride, F-, and major complexes (HF(aq)0, AlF2+, AlF2+ and AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-, FeF2+, FeF2+, MgF+ and BF2(OH)2- may comprise 1-10% when the concentrations of the appropriate components are high. According to the simulation results by PHREEQC and calculated results, the ratio of main fluoride species to total fluoride varies as a function of pH and the concentrations and ratios of F and Al. ?? 2011.

  17. Efficacy of silver diamine fluoride as an antibacterial as well as antiplaque agent compared to fluoride varnish and acidulated phosphate fluoride gel: An in vivo study

    Shalin Shah; Vijay Bhaskar; Karthik Venkataraghavan; Prashant Choudhary; M Ganesh; Krishna Trivedi

    2013-01-01

    Background: Silver diamine fluoride (SDF) is already proven as an antibacterial agent in vitro. Present study was formulated to compare the efficacy of SDF as an antibacterial as well as antiplaque agent in vivo with fluoride varnish and acidulated phosphate fluoride (APF) gel. Study Design: Total 123 children (male = 82, female = 41) were included in the study for a period of 18 months. Children were divided into three different groups-Group 1: SDF; Group 2: fluoride varnish; and Group 3...

  18. Chemisorption of uranium hexa-fluoride on sodium fluoride pellets

    This paper comprises kinetics of chemical reaction or rather chemisorption of uranium hexafluoride gas on sodium fluoride pellets. The chemisorption is essentially irreversible at room temperature, while the process reverses at high temperature above 280 deg C. This chemisorption process was experimentally conducted in static condition at room temperature and its kinetics was studied. In the experiments, practically pure UF6 was used and the effects of gas pressure and weight of NaF pellets, were studied. In this heterogenous reaction, in which diffusion through ash layer is followed by chemical reaction, the reaction part is instantaneous and is first order with respect to gas concentration. Since the process of chemisorption is not only pure chemical reaction but also gas diffusion through ash layer, the rate constant depreciates with the percentage loading of UF6 on NaF pellets. The kinetic equation for the above process has been established for a particular size of NaF pellets and pellet porosity. (author)

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

    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). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

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

    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). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

  1. Determination of Fluoride in the Bottled Drinking Waters in Iran

    Amanlou, Massoud; Hosseinpour, Maedeh; Azizian, Homa; Khoshayand, Mohammad Reza; Navabpoor, Mojtaba; Souri, Effat

    2010-01-01

    Fluoride is recognized as an effective agent for dental caries prevention. Generally, the main source of fluoride intake is drinking water. In this study, fluoride content in 18 commercial brands of bottled waters was investigated. Six samples from each batch of 18 Iranian commercial brands of bottled waters were supplied. The fluoride content of samples was analyzed by Fluoride Ion Selective Electrode. The mean ± SD fluoride content of the bottled waters was 0.202 ± 0.00152 mg/L with a range...

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

    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

  3. Global Measurements of Atmospheric Sulfuryl Fluoride

    Mühle, J.; Harth, C. M.; Salameh, P.; Miller, B. R.; Weiss, R. F.; Porter, L. W.; Fraser, P. J.; Greally, B. R.; O'Doherty, S.

    2006-12-01

    Sulfuryl fluoride (SO2F2) is used increasingly as a fumigant, but information about its emissions to the atmosphere is limited. Its atmospheric fate and lifetime are uncertain, with hydrolysis in the basic surface waters of the oceans a likely dominant sink, and its roles as a greenhouse gas and as a sulfur source to the stratosphere are unknown. We present here the first results of two years of high-frequency high-precision in situ observations of sulfuryl fluoride in the AGAGE (Advanced Global Atmospheric Gases Experiment) global measurement program. At La Jolla, California, baseline conditions are rarely achieved, and pollution events of up to 1.7 ppb (the exposure limit is 5 ppm) from nearby structural fumigation are common. At the Mace Head, Ireland, and Cape Grim, Tasmania, AGAGE stations, baseline conditions are observed with mixing ratios at the beginning of 2005 of ~1.0 ppt and ~0.9 ppt, respectively. Measured growth rates at these stations are ~0.06 ppt per year and ~0.04 ppt per year, respectively. Using these preliminary results and assuming no significant emissions in the southern hemisphere, a simple 2-box model can be used to estimate the tropospheric lifetime of sulfuryl fluoride as about one and a half decades, which is substantially longer than previous industry estimates. The corresponding modeled sulfuryl fluoride flux to the troposphere is ~2 x 109 g per year. Based on these initial measurements, the current global warming contribution of sulfuryl fluoride is likely small. Although the lifetime of sulfuryl fluoride is longer than that of carbonyl sulfide, sulfuryl fluoride is likely less important as source of sulfur to the stratosphere, due to its low atmospheric mixing ratio.

  4. Caries inhibition by fluoride-releasing primers.

    Kerber, L J; Donly, K J

    1993-10-01

    This study evaluated the caries inhibition of dentin primers with the addition of fluoride. Two standardized Class V preparations were placed in 20 molars, the gingival margin placed below the cementoenamel junction and the occlusal margin placed in enamel. Two dentin primers (Syntac and ScotchPrep) were placed in equal numbers of 20 preparations, according to manufacturer's instructions. Ammonium fluoride (10% by weight) was then added to these primers and they were placed in the remaining 20 preparations, opposing the non-fluoridated primer of the same system. All teeth were then restored with a non-fluoridated resin composite. All teeth were subjected to an artificial caries challenge (pH 4.2) for 5 days. Sections of 100 microns were obtained, photographed under polarized light microscopy, then demineralized areas were quantitated by digitization. Results demonstrated the mean areas (mm2 +/- S.D.) demineralization at 0.25 mm, 0.5 mm and 1.0 mm from the restoration margin to be: Syntac/fluoride (1.44 +/- 0.49, 1.68 +/- 0.54, 3.72 +/- 0.74); Syntac (1.99 +/- 0.58, 1.50 +/- 0.35, 2.98 +/- 1.26); ScotchPrep/fluoride (1.23 +/- 0.68, 1.55 +/- 0.64, 3.08 +/- 1.16); ScotchPrep (1.90 +/- 0.83, 1.71 +/- .038, 3.36 +/- 0.62). A paired t-test indicated primers with fluoride to demonstrate significantly less demineralization 0.25 mm from the restoration margin (P < 0.07). PMID:7880460

  5. Thermodynamic data-base for metal fluorides

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

  6. Thermodynamic data-base for metal fluorides

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

    2001-05-01

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

  7. Emissions of fluorides from welding processes.

    Szewczyńska, Małgorzata; Pągowska, Emilia; Pyrzyńska, Krystyna

    2015-11-01

    The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H. Vincent and D. Mark at the Institute of Occupational Medicine (IOM), personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-N-trimethylammonium bromide (CTAB) were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8μg/L and 24μg/L, respectively. The linear range of calibration was 0.01-10mg/L, which corresponds to 0.0001-0.1mg of fluorides per m(3) in collection of a 20L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20-1.82mg/m(3), while the inhalable fraction contained 0.23-1.96mg/m(3) of fluorides during an eight-hour working day in the welding room. PMID:26574102

  8. The kinetics of fluoride uptake by synthetic hydroxyapatite

    Takudzwa Gomwe

    2012-03-01

    Full Text Available The kinetics of fluoride uptake by synthetic hydroxyapatite from aqueous solution has been studied. Experiments involved exposing 0.1 g of synthetic hydroxyapatite to 5 cm3 of sodium fluoride solution in the concentration range 100-1000 ppm fluoride and determining fluoride concentration at regular time intervals with a fluoride ion-selective electrode. In all cases, uptake was found to follow pseudo-second order kinetics with correlation coefficients of at least 0.998; all systems equilibrated by 24 hours with equilibrium uptake values that varied with the initial fluoride concentration. The kinetic results differ from those previously reported for much lower concentrations of fluoride, but in the present case, the concentrations were of clinical relevance, as they are those used in fluoride-containing dental products. Further work is necessary to determine how well these findings model uptake by natural hydroxyapatite and hence the extent to which they might apply in vivo.

  9. Removing Fluoride Ions with Continously Fed Activated Alumina.

    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)

  10. A simple and colorimetric fluoride receptor and its fluoride-responsive organogel

    In this paper, a new p-nitrophenylhydrozine-based anion receptor 1 containing cholesterol group had been designed and synthesized. It could selectively recognize fluoride among different anions tested with color changes from pale yellow to red for visual detection. Simultaneously, it could gel in cyclohexane, and the gel was also fluoride-responsive. When treated with TBAF (tetra-n-butylammonium fluoride), the gel could undergo gel–sol transition accompanied by color, morphology and surface changes. The binding mechanism had been investigated by UV–vis and 1HNMR (proton nuclear magnetic resonance spectra) titrations. From SEM (scanning electron microscope), SAXS (small-angle X-ray scattering), IR (Infrared Spectroscopy) and CA (contact angle) experiments, it was indicated that the addition of F− could destroy the molecule assembly of host 1 in the gel state, thus resulting in the gel-to-sol transition due to the binding site competition effect. To the best of our knowledge, this was the simplest fluoride-responsive organogel with high selectivity. Highlights: ► A novel kind receptor for selective recognition of fluoride had been designed. ► Its organogel was also fluoride-responsive. ► This is the simplest fluoride-responsive organogel with high selectivity.

  11. Parabens do not increase fluoride uptake by dental enamel

    Vanessa Silva Tramontino; Daniela Labbate; Tabchoury, Cínthia Pereira Machado; Jaime Aparecido CURY

    2010-01-01

    Objective: To evaluate whether methylparaben and propylparaben, which present a similar chemical structure, increase fluoride uptake by demineralized dental enamel when present in buffered solutions. Methods: The study comprised an in vitro experiment using blocks of bovine dental enamel with artificial carious lesions. Enamel blocks were exposed to the following treatment (n=12): fluoride solution (200 ppm fluoride) - control; solution containing fluoride and 13 mM methylparaben; solution co...

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

    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

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

    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. PMID:25136045

  14. Preparation of uranium ingots from double fluorides

    A simple method has been developed for the preparation of uranium double fluorides and has given a new impetus to the study of the reduction of these compounds with a view to obtaining very pure uranium ingots. This reduction can be carried out using calcium or magnesium as the reducing agent, this latter metal being very interesting from the practical point of view. A comparative study of the heat balances of the reduction processes for the double fluorides and for uranium tetrafluoride has shown that reduction of the double fluorides is possible. The exact experimental conditions for these reductions have been determined. Our study has shown in particular that the reduction of the double salt UF4, CaF2 by magnesium leads to the production of small (20 to 500 g) samples of high-purity uranium with a yield of 99 per cent. (author)

  15. Uranyl fluoride luminescence in acidic aqueous solutions

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO2F2. Studies on the effect of added LiNO3 or Na2WO4·2H2O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF6 content of WF6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF6

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

    Vieira, A; Ruben, JL; Huysmans, MCDNJM

    2005-01-01

    This study aimed at evaluating the effect of 1 and 4% titanium tetrafluoride (TiF4) gels, amine fluoride (AmF) 1 and 0.25% and a fluoride varnish (FP) on the prevention of dental erosion. Two experimental groups served as controls, one with no pretreatment and another one pre-treated with a fluoride-free varnish (FP-blanco). Dental erosion was modelled using bovine enamel samples submitted to alternate cycles of acid exposure in citric acid and remineralization in artificial saliva. Calcium l...

  17. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    2010-04-01

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

  18. Cancer incidence and mortality in workers exposed to fluoride

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

    1992-01-01

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

  19. Coprecipitation of iron and silver with barium fluoride

    Distribution of trace contaminants of iron and silver at coprecipitation of barium fluoride is studied in present work. It is defined that iron almost completely coprecipitated with barium fluoride in wide range of ph 5.5-12. Silver coprecipitated with barium fluoride in ph range 4-7. The value of coprecipitation varies from 94% to 100%.

  20. Plasma processing of fluoride solutions of refractory rare metals

    Gutsol, A.F. [Institute of Chemistry and Technology of Less-Common Elements and Raw Materials, Murmanskaya oblast` (Russian Federation)

    1995-09-01

    Features of plasma processing of fluoride solutions of refractory metals were studied. It was shown that pyrohydrolysis of niobium, tantalum, and titanium fluorides occurs in the gas phase, thus providing fine oxide powders. The pyrohydrolysis of low-volatility zirconium fluoride occurs in the solid phase, yielding oxide particles corresponding to the size of initial droplets.

  1. Onderzoek naar de bepaling van fluoride in een doorstroomsysteem

    Neele J; Nagtegaal-Wouterse GWM; Reijnders HFR

    1989-01-01

    Een snelle methode voor de bepaling van fluoride in een doorstroomsysteem met potentiometrische detectie en een lage onderste analysegrens is ontwikkeld. De mate waarin fluoride uit fluoride-verbindingen wordt vrijgemaakt door complexvormende stoffen is gevolgd om vast te stellen hoeveel tijd hierv

  2. Synthesis of reagents for fluoride technologies

    Gordienko; P.; S.; Kolzunov; V.; A.; Dostovalov; V.; A.; Kaidalova; T.; A.

    2005-01-01

    Growing demand for fluorinating reagents to be used in rare-metal industry has stimulated conducting research in the field of production for these reagents. That is why the fluorinating reagents production has recently formed an independent segment of industry. Main industrial fluorinating reagents include hydrofluoric acid, anhydrous hydrogen fluoride, technical ammonium hydrodifluoride, fluorosilicic acid and its salts. To produce technical etching acid, fluor-spar with calcium fluoride content at least 92% is used in most cases. To produce anhydrous hydrogen fluoride, fluor-spar with calcium fluoride content 96 %-97 % is necessary. The fluorine-containing raw materials refinement from silica by means of flotation makes the fluorinating reagents production substantially more expensive. In this work we have attempted to process unconcentrated raw materials by fluorine removal in the form of volatile silicon tetrafluoride. In this process silicon tetrafluoride was recovered by liquid ammonia with subsequent hydrolysis of the formed ammonia hexafluorosilicate. Hydrolysis occurred according to the reaction:(NH4)2 SiF6 + 4NH3 + 2 H2O= 6NH4F+ SiO2 The products of the ammonia hexafluorosilicate hydrolysis included ammonia fluoride and amorphous silica gel ("white soot") as by-product. This "white soot" was of high purity-with main component content 99.95% and total admixture content 0.05%. Silica gel is a superfine material with specific surface of 267.6 m2/g and is recommended as filler in the production of rubber, plastics and for other applications.Ammonia fluoride was transformed into ammonia hydrodifluoride (main processing product) according to the reaction:2NH4F→NH3+NH4 HF2 It was stated that the NH4F: NH4 HF2 ratio depends on boiling point temperature-with its increase the ammonia hydrofluoride concentration in solution increases as well.

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

    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. PMID:26736058

  4. Micro-determination of fluoride by means of metallic sodium fusion and using fluoride-sensitive electrode.

    Roy J; Rane S; Ghani A; Chaudhury C

    1993-01-01

    A simple and accurate method to determine the content of fluoride in non-volatile organofluoro compounds or in biological samples has been developed. The method includes the metallic sodium fusion followed by quantitative estimation of fluoride using fluoride-sensitive electrode.

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

    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.

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

    Dhull K

    2009-03-01

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

  7. Manufacture of high purity low arsenic anhydrous hydrogen fluoride

    A process for manufacturing anhydrous hydrogen fluoride with reduced levels of arsenic impurity from arsenic contaminated anhydrous hydrogen fluoride is described which comprises: (a) contacting the anhydrous hydrogen fluoride with an effective amount of hydrogen peroxide to oxidize the arsenic impurity in the presence of a catalyst which comprises a catalytic amount of (i) molybdenum or an inorganic molybdenum compound and (ii) a phosphate compound, at a temperature and for a period of time sufficient to oxidize volatile trivalent arsenic impurities in the anhydrous hydrogen fluoride to non-volatile pentavalent arsenic compounds, and (b) distilling the resulting mixture and recovering anhydrous hydrogen fluoride with reduced levels of arsenic impurity

  8. Fluoride: a risk factor for inflammatory bowel disease?

    Follin-Arbelet, Benoit; Moum, Bjørn

    2016-09-01

    Although the association between inflammatory bowel disease (IBD) and oral hygiene has been noticed before, there has been little research on prolonged fluoride exposure as a possible risk factor. In the presented cases, exposure to fluoride seems indirectly associated with higher incidence of IBD. Fluoride toxicology and epidemiology documents frequent unspecific chronic gastrointestinal symptoms and intestinal inflammation. Efflux genes that confer resistance to environmental fluoride may select for IBD associated gut microbiota and therefore be involved in the pathogenesis. Together these multidisciplinary results argue for further investigation on the hypothesis of fluoride as a risk factor for IBD. PMID:27199224

  9. Fluoride inhibition of proton-translocating ATPases of oral bacteria.

    Sutton, S V; Bender, G R; Marquis, R E

    1987-01-01

    The ATPases of isolated membranes of lactic acid bacteria were found to be inhibited by fluoride in a complex manner. Among the enzymes tested, that of Streptococcus mutans GS-5 was the most sensitive to fluoride, and the initial rate of hydrolysis of ATP was reduced 50% by approximately 3 mM fluoride. The enzyme of Lactobacillus casei ATCC 4646 was the most resistant, and about 25 mM fluoride was required for 50% inhibition. The response to fluoride appeared to involve reversible, noncompeti...

  10. Oral Fluoride Including Drinking Water in Prevention of Tooth Decay

    Vitoria I

    2015-01-01

    Herein we present a review of the role of oral fluoride in the prevention of tooth decay, together with updated recommendations on fluoride supplements. Fluoridation of public drinking water is still considered effective, but the recommended level of fluoride is now 0.7 mg/L, compared with the previously recommended range of 0.7-1.2 mg/L. Oral fluoride supplements are currently not restricted to the children at high risk for tooth decay, but recommended initiate at 6 months&nbs...

  11. Actinide measurements by AMS using fluoride matrices

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

    2015-10-01

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

  12. THE DEVELOPMENT OF AN INDIGENOUS FLUORIDE FILTER

    Given that an essential component of the design is that it can be adapted for use throughout the world, the potential media investigated are those available in the regions containing fluoride contaminated groundwater. From the literature, wood charcoal, bone char, laterite and...

  13. Total Fluoride Intake by Children from a Tropical Brazilian City.

    Lima, Carolina V; Cury, Jaime A; Vale, Glauber C; Lima, Marina D M; Moura, Lúcia de Fátima A D; Moura, Marcoeli Silva de

    2015-01-01

    The main sources of fluoride intake by children are fluoridated water and toothpaste. Little has been studied regarding fluoride intake from these sources in regions with tropical climates and high temperatures throughout the year. This study aimed to determine the amount of fluoride ingested from diet and tooth brushing by children who live in a city with a tropical climate. Sixty-seven children from Teresina, Piauí, Brazil, took part in this study. The city's water supply was optimally fluoridated. The duplicate-diet method was used to determine the fluoride intake from diet. The intake of fluoride from dentifrice was determined by subtracting the amount of fluoride placed on the toothbrush and that recovered after brushing. The concentration of fluoride was measured using an ion-specific electrode and is expressed as milligrams/kilogram of body weight/day. The mean (±SD) total amount was 0.071 ± 0.036 mg F/kg body weight/day, and the relative contributions of diet and toothpaste were 0.025 ± 0.010 and 0.046 ± 0.035, respectively. The factors associated with fluoride intake from toothpaste were: use of children's toothpaste (p = 0.003), use of large amounts of toothpaste (p fluoride ingested by most children who live in a Brazilian city with a tropical climate is considered safe in terms of the risk of dental fluorosis. PMID:26655142

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

    Jaime A. Cury

    2013-11-01

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

  15. Estimation of atmospheric fluoride by limed filter papers

    The limed filter paper method of static sampling of atmospheric fluoride is reviewed in this report. Use of the technique, in conjunction with precise measurement of the absorbed fluoride and calibration with dynamic air sampling techniques, to estimate atmospheric fluoride levels, is considered to give only qualitative data (± 50%). The limed filter paper method is site specific due to variations in meteorological conditions. Its main value is to indicate seasonal and annual trends in fluoride exposure of vegetation. Subject to these considerations, the lower and upper limits of atmospheric fluoride exposure and the applicability to atmospheric fluoride estimation under routine or emergency fluoride release conditions are discussed, with special emphasis on the limiting factors

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

    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 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 dental fluorosis in areas where the fluoride concentration was high.

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

    Rirattanapong, Opas; Rirattanapong, Praphasri

    2016-01-01

    Abstract. In Thailand, the consumption of soy milk products is common but there is limited data about their fluoride content. The purpose of this study was to es- timate the fluoride content of soy milk products available in Thailand. Fluoride content was determined for 76 brands of soy milk using a F-ion-specific electrode. The fluoride concentrations ranged from 0.01 to 3.78 μg/ml. The fluoride content was not related to sugar content, soy bean content or the sterilization process. Among 3 brands of soy milk containing tea powder extract, the fluoride content was high (1.25 to 3.78 μg/ml). Most brands of soy milk tested in our study had fluoride content below the optimal daily intake but brands containing tea powder extract if consumed by children may increase their risk for fluorosis. PMID:27086437

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

    Suzely Adas Saliba MOIMAZ

    2013-01-01

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

  19. Effects of fluoridated milk on root dentin remineralization.

    Wolfgang H Arnold

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

  20. Fluoride uptake into the developing enamel and dentine of sheep incisors following daily ingestion of fluoridated milk or water

    The caries preventive action of fluoride is common knowledge, although some of the mechanisms involved remain equivocal. At present, raised local levels of fluoride at, or in, the surface of tooth enamel is the most commonly accepted explanation of the anti-cariogenic action of fluoride. However, fluoride incorporated as fluorapatite into the tooth during its formation remains a possible alternative or complementary anti-cariogenic mechanism. If so, regular ingestion of fluoride during tooth formation is beneficial. Although use of fluoridated water is the preferred method in public health programmes, access to suitable potable water is required, and often this in not feasible. Fresh, preserved, or dried cow's milk products are widely used as nutritional and dietary items in most populations, particularly for young children. Milk is a practical, controllable means for regular delivery of fluoride. Processing of milk is commonly centralised and uses standardised conditions, allowing easy supplementation of fluoride for distribution to communities. The purpose of this study was to resolve the question of availability of fluoride ingested in milk compared with fluoride ingested in water by measuring fluoride deposition in the developing permanent incisors of young sheep. Incisors were analysed using a proton microprobe. (author). 18 refs., 1 tabs., 3 figs

  1. Water Fluoridation: A Critical Review of the Physiological Effects of Ingested Fluoride as a Public Health Intervention

    Stephen Peckham

    2014-01-01

    Full Text Available Fluorine is the world’s 13th most abundant element and constitutes 0.08% of the Earth crust. It has the highest electronegativity of all elements. Fluoride is widely distributed in the environment, occurring in the air, soils, rocks, and water. Although fluoride is used industrially in a fluorine compound, the manufacture of ceramics, pesticides, aerosol propellants, refrigerants, glassware, and Teflon cookware, it is a generally unwanted byproduct of aluminium, fertilizer, and iron ore manufacture. The medicinal use of fluorides for the prevention of dental caries began in January 1945 when community water supplies in Grand Rapids, United States, were fluoridated to a level of 1 ppm as a dental caries prevention measure. However, water fluoridation remains a controversial public health measure. This paper reviews the human health effects of fluoride. The authors conclude that available evidence suggests that fluoride has a potential to cause major adverse human health problems, while having only a modest dental caries prevention effect. As part of efforts to reduce hazardous fluoride ingestion, the practice of artificial water fluoridation should be reconsidered globally, while industrial safety measures need to be tightened in order to reduce unethical discharge of fluoride compounds into the environment. Public health approaches for global dental caries reduction that do not involve systemic ingestion of fluoride are urgently needed.

  2. Effective use of fluorides for the prevention of dental caries in the 21st century

    Petersen, Poul Erik; Lennon, Michael A

    2004-01-01

    , due to changing living conditions and dietary habits, and inadequate exposure to fluorides. Research on the oral health effects of fluoride started around 100 years ago; the focus has been on the link between water and fluorides and dental caries and fluorosis, topical fluoride applications, fluoride...... toothpastes, and salt and milk fluoridation. Most recently, efforts have been made to summarize the extensive database through systematic reviews. Such reviews concluded that water fluoridation and use of fluoride toothpastes and mouthrinses significantly reduce the prevalence of dental caries. WHO recommends...... fluoridation schemes may be considered for prevention of dental caries....

  3. Fluoride content of clay minerals and argillaceous earth materials

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

    1977-01-01

    A reliable method, utilizing a fluoride ion-selective electrode, is described for the determination of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ??5% at different levels of fluoride concentration. Data are presented for various clay minerals and for the clays and shales. Fluoride values range from 44 ppm (0.0044%) for nontronite from Colfax, WA, to 51,800 ppm (5.18%) for hectorite from Hector, CA. In general, clays formed under hydrothermal conditions are relatively high in fluoride content, provided the hydrothermal waters are high in fluoride content. Besides hectorite, dickite from Ouray, CO, was found to contain more than 50 times as much fluoride (6700 ppm) as highly crystalline geode kaolinite (125 ppm). The clay stratum immediately overlying a fluorite mineralized zone in southern Illinois was found to have a higher fluoride content than the same stratum in a nonmineralized zone approximately 1 mile away. Nonmarine shales in contact with Australian coals were found to be lower in fluoride content than were marine shales in contact with Illinois coals. It is believed that, in certain instances, peak shifts on DTA curves of similar clay minerals are the result of significant differences in their fluoride content. ?? 1977.

  4. Community water fluoridation and caries prevention: a critical review.

    Pizzo, Giuseppe; Piscopo, Maria R; Pizzo, Ignazio; Giuliana, Giovanna

    2007-09-01

    The aim of this paper was to critically review the current role of community water fluoridation in preventing dental caries. Original articles and reviews published in English language from January 2001 to June 2006 were selected through MEDLINE database. Other sources were taken from the references of the selected papers. For the past 50 years community water fluoridation has been considered the milestone of caries prevention and as one of the major public health measures of the 20th century. However, it is now accepted that the primary cariostatic action of fluoride occurs after tooth eruption. Moreover, the caries reduction directly attributable to water fluoridation have declined in the last decades as the use of topical fluoride had become more widespread, whereas enamel fluorosis has been reported as an emerging problem in fluoridated areas. Several studies conducted in fluoridated and nonfluoridated communities suggested that this method of delivering fluoride may be unnecessary for caries prevention, particularly in the industrialized countries where the caries level has became low. Although water fluoridation may still be a relevant public health measure in poor and disadvantaged populations, the use of topical fluoride offers an optimal opportunity to prevent caries among people living in both industrialized and developing countries. PMID:17333303

  5. Parabens do not increase fluoride uptake by dental enamel

    Vanessa Silva Tramontino

    2010-04-01

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

  6. Urinary fluoride concentration as an estimator of welding fume exposure from basic electrodes.

    Sjörgren, B; Hedström, L; Lindstedt, G.

    1984-01-01

    Urinary fluoride concentrations have been measured in electric arc welders using basic electrodes. The fluoride concentration and the total welding fume concentration in air showed a linear relation with postshift urinary fluoride concentration. The measured concentrations were below internationally recommended postshift urinary fluoride concentrations believed to cause fluorosis. Biological monitoring by postshift urinary fluoride measurements is evaluated for the prediction of total welding...

  7. Analysis of differentially expressed genes between fluoride-sensitive and fluoride-endurable individuals in midgut of silkworm, Bombyx mori.

    Qian, Heying; Li, Gang; He, Qingling; Zhang, Huaguang; Xu, Anying

    2016-08-15

    Fluoride tolerance is an economically important trait of silkworm. Near-isogenic lines (NILs) of the dominant endurance to fluoride (Def) gene in Bombyx mori has been constructed before. Here, we analyzed the gene expression profiles of midgut of fluoride-sensitive and fluoride-endurable individuals of Def NILs by using high-throughput Illumina sequencing technology and bioinformatics tools, and identified differentially expressed genes between these individuals. A total of 3,612,399 and 3,567,631 clean tags for the libraries of fluoride-endurable and fluoride-sensitive individuals were obtained, which corresponded to 32,933 and 43,976 distinct clean tags, respectively. Analysis of differentially expressed genes indicates that 241 genes are differentially expressed between the two libraries. Among the 241 genes, 30 are up-regulated and 211 are down-regulated in fluoride-endurable individuals. Pathway enrichment analysis demonstrates that genes related to ribosomes, pancreatic secretion, steroid biosynthesis, glutathione metabolism, steroid biosynthesis, and glycerolipid metabolism are down-regulated in fluoride-endurable individuals. qRT-PCR was conducted to confirm the results of the DGE. The present study analyzed differential expression of related genes and tried to find out whether the crucial genes were related to fluoride detoxification which might elucidate fluoride effect and provide a new way in the fluorosis research. PMID:27106117

  8. The Effect of Calcium Pre-Rinse on Salivary Fluoride After 900 ppm Fluoride Mouthwash: A Randomized Clinical Trial

    Nahid Ramazani

    2013-01-01

    Full Text Available Objective: Calcium fluoride deposit during fluoride application. Uptake and retention of fluoride by saliva depends generally on the concentration of calcium. In this study, the ef-fect of calcium pre-rinse on salivary fluoride concentration after a 900 ppm fluoride mouthwash was investigated.Materials and Methods: This cross-over double-blind randomized clinical trial was con-ducted in a girls' dormitory in Zahedan University of Medical Sciences, southeast Iran. In this study, 42 female dental students were chosen using simple randomization. During the first phase, 21 subjects (group A used fluoride rinse (F regimen and the remaining (group B used calcium pre-rinse followed immediately by fluoride rinse (Ca + F regi-men. In the second phase, participants rinsed using the mouthwashes not previously used. Prior to each phase prophylaxis was performed and no fluoridated product was used dur-ing a two-week interval between the phases. Salivary samples were taken immediately be-fore (baseline, 1 and 12 hours after rinsing. The salivary fluoride concentration was de-termined using fluoride sensitive electrode. Repeated measures ANOVA was used for sta-tistical analysis and the significance level was set at P<0.05.Results: There was significant difference between fluoride concentrations at different time points (P< 0.001. Significant differences were observed when the different time points of two regimens were examined. In contrast to this, the baseline before using F regimen and the baseline before using Ca + F regimen did not show any significance (P= 0.070.Conclusion: Pre-rinsing with calcium before fluoride is recommended because of signifi-cant increases in salivary fluoride concentration.

  9. Revisiting the thermochemistry of chlorine fluorides

    Sánchez, H R

    2016-01-01

    In this work, accurate calculations of standard enthalpies of formation of chlorine fluorides (ClF$_n$, n=1--7; Cl$_2$F and Cl$_3$F$_2$) were performed through the isodesmic reactions scheme. It is argued that, for many chlorine fluorides, the gold standard method of quantum chemistry (CCSD(T)) is not capable to predict enthalpy values nearing chemical accuracy if atomization scheme is used. This is underpinned by a thorough analysis of total atomization energy results and the inspection of multireference features of these compounds. Other thermodynamic quantities were also calculated at different temperatures. In order to complement the energetic description, elimination curves were studied through density functional theory as a computationally affordable alternative to highly correlated wave function-based methods.

  10. Plutonium oxide obtainment from a plutonium fluoride

    The need to recover the Pu existing in the Alpha Facility for the experimental fabrication of mixed oxides fuel elements (U,Pu)O2, its recovery has been set up from the F4Pu available at the laboratory. To fulfill the strict specifications on fluorides in nuclear fuels, it was necessary to precisely adjust the purification phase. This paper describes the chemical process for the PuO2 obtainment from F4Pu. F4Pu was dissolved in nitric acid, adding aluminium nitrate. The concentration in the medium decreases due to the complexes formation with fluorides and this allows the full dissolution of the salt. Pu separation was carried out by the treatment with RESINE DOWEX in columns. After purification with successive washes in NO3H7M, Pu elution retained in the column was performed. Finally, it precipitated as Pu IV oxalate and PuO2 was obtained by calcination at 700 deg C. (Author)

  11. Fluoridation and tooth wear in Irish adults.

    Burke, F M

    2010-10-01

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

  12. The hydride fluoride crystal structure database, HFD

    Gingl, F.; Gelato, L.; Yvon, K. [Geneva Univ. (Switzerland). Lab. Crystallographie aux Rayons X

    1997-05-20

    HFD is a new data base containing crystal structure information on more than one thousand metal hydrides and fluorides. It includes space group, cell parameters, standardized atom positions, site occupancies and references. The compilation is critical as only refined crystal structures are considered and the data are checked for internal consistency. It is comprehensive as structural information is extracted from all major scientific journals, and it is continuously updated. HFD can be searched according to various criteria such as symmetry, chemical elements, composition etc. The primary motivation for creating HFD was to predict new metal hydrides and to study their structural analogies with metal fluorides. However, HFD can also be used for other applications such as the simulation of diffraction patterns and the drawing of crystal structures. (orig.) 13 refs.

  13. Fluoride solid electrolytes containing rare earth elements

    Viera Trnovcová; Pavel P. Fedorov; Ivan Furár

    2008-01-01

    Relations between the structure, ionic conductivity and dielectric properties of fluoride systems of different structures containing rare earth elements were presented. Superionic conductivities, by fluoride ions, of fluorite-structured (MF2-REF3, M=Ba, Pb, RE=La-Lu, Sc, Y), orthorhombic (REF3, RE=Tb-Er,Y), tysonite-structured (REF3-MF2, RE=La-Nd, M=Sr), monoclinic (BaRE2F8, RE=Ho-Yb, Y) fluoride single crystals and eutectic composites (LiF-REF3, RE=La-Gd,Y) were compared. Anisotropy of electrical properties of crystals with a lower symmetry was explained by modeling optimum ionic paths. For explanation of concentration dependences of fast ionic conductivity, models of aggregation of defects into clusters were proposed. In fluorite-structured crystals, the highest ionic conductivity was found for PbF2: 7 mol% ScF3 (at 500 K, σ500=0.13 S/cm). In tysonite-structured crystals, the highest ionic conductivity was found for LaF3: 3 mol% SrF2 (σ500=2.4×10-2 S/cm). Different types of coordination polyhedrons and their different linking in orthorhombic and tysonite structure explained large differences between conductivities in both structures. Eutectic systems, prepared as directionally solidified composites, enabled to study some orthorhombic fluoride phases (GdF3, SmF3), which cannot be prepared as single crystals. An influence of the orthorhombic-tysonite phase transition on the ionic conductivity was shown.

  14. Health protection: Fluoridation and dental health.

    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 knowl...

  15. Delivery Challenges for Fluoride, Chlorhexidine and Xylitol

    Featherstone, John DB

    2006-01-01

    The progression or reversal of dental caries is determined by the balance between pathological and protective factors. It is well established that a) fluoride inhibits demineralization and enhances remineralization, b) chlorhexidine reduces the cariogenic bacterial challenge, and c) xylitol is non-cariogenic and has antibacterial properties. The challenge that we face is how best to deliver these anti-caries entities at true therapeutic levels, over time, to favorably tip the caries balance. ...

  16. Effect of fluoride toothpastes on enamel demineralization

    Gintner Zeno

    2006-06-01

    Full Text Available Abstract Background It was the aim of this study to investigate the effect of four different toothpastes with differing fluoride compounds on enamel remineralization. Methods A 3 × 3 mm window on the enamel surface of 90 human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 6 groups and the lower half of the window was covered with varnish serving as control. The teeth were immersed in a toothpaste slurry containing: placebo tooth paste (group 1; remineralization solution (group 2; Elmex Anticaries (group 3; Elmex Sensitive (group 4; Blend-a-med Complete (group 5 and Colgate GRF (group 6. Ten teeth of each group were used for the determination of the F- content in the superficial enamel layer and acid solubility of enamel expressed in soluble phosphorus. Of 6 teeth of each group serial sections were cut and investigated with polarization light microscopy (PLM and quantitative energy dispersive X-ray analysis (EDX. Results The PLM results showed an increased remineralization of the lesion body in the Elmex Anticaries, Elmex Sensitive and Colgate GRF group but not in the Blend-a-med group. A statistically significant higher Ca content was found in the Elmex Anticaries group. The fluoride content in the superficial enamel layer was significantly increased in both Elmex groups and the Blend-a-med group. Phosphorus solubility was significantly decreased in both Elmex groups and the Blend-a-med group. Conclusion It can be concluded that amine fluoride compounds in toothpastes result in a clearly marked remineralization of caries like enamel lesions followed by sodium fluoride and sodium monofluorophosphate formulations.

  17. Necessity to review the Brazilian regulation about fluoride toothpastes

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

    2015-01-01

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

  18. [Problems of fluoride dosing to infants for dental fluorosis prevention].

    Davydov, B N; Borinskaia, E Iu; Kushnir, S M; Borinskiĭ, Iu N; Beliaev, V V

    2011-01-01

    Fluoride content in drinking water, breast milk, cow milk, additional food for newborns prepared with water containing different amount of fluoride was determined. Fluoride excretion in urine since the first days of birth and up to 4 months of postnatal development was investigated in breast and artificially fed infants. When a neonate was fed with breast milk, fluoride was received in the amount no more than 20 mkg/day. The additional food contained fluoride which water mainly had. Water with high level of fluorine increased its content in the additional food up to the values not comparable to those in breast milk that presented danger of dental fluorosis development. Data on fluorine content in drinking water were absolutely necessary to calculate daily fluorides consumption by infants and to prevent dental fluorosis. PMID:21378727

  19. The effective use of fluorides in public health

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

    2005-01-01

    , 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......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...

  20. High Fluoride Dentifrices for Elderly and Vulnerable Adults

    Ekstrand, Kim Rud

    The primary aim of this work is to present the available evidence that toothpastes containing >1,500 ppm fluoride (2,500-2,800 and 5,000 ppm F) provide an additional caries preventive effect on root caries lesions in elderly patients compared to traditional dentifrices (1,000-1,450 ppm F). The...... secondary aim of this paper is to discuss why high fluoride dentifrices in general should perform better than traditional F-containing toothpaste. When examining the few studies that have considered the preventive benefits of high fluoride products on root caries the relative risk appears to be around 0.......5, and the risk can thus be halved by exchanging traditional F-containing toothpaste for toothpaste containing 5,000 ppm F. There is reasonable evidence that high fluoride dentifrices significantly increase the fluoride concentration in saliva during the day and the fluoride concentration in plaque...

  1. Necessity to review the Brazilian regulation about fluoride toothpastes

    Jaime Aparecido Cury

    2015-01-01

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

  2. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  3. Distribution of fluoride in ground water of West Virginia

    Mathes, M.V.; Waldron, M.C.

    1993-01-01

    This report describes the results of a study by the U.S. Geological Survey, in cooperation with the West Virginia Geological and Economic Survey, to evaluate the distribution of fluoride in ground water of West Virginia. Fluoride is a natural chemical constituent in domestic and public water supplies in West Virginia. Fluoride concentrations of about 1.0 milligram per liter in drinking water are beneficial to dental health. Concentrations greater than 2.0 milligrams per liter, however, could harm teeth and bones. Fluoride concentra- tions in ground water of West Virginia range from less than 0.1 to 12 milligrams per liter. Fluoride concentrations that exceed 2.0 milligrams per liter are found in wells drilled to all depths, wells drilled in all topographic settings, and wells drilled into most geologic units. Most fluoride concentrations that exceed 2.0 milligrams per liter are located at sites clustered in the northwestern part of the State.

  4. Bone scintigraphy in fluoride treated osteoporosis

    Quantitative bone scintigraphy was performed on 23 white females with post-menopausal osteoporosis and vertebral compression fractures. These patients were then entered into a randomized, double-blind clinical trial or sodium fluoride therapy (NaF=14, placebo=9) which included repeat bone scintigraphy every six months. Scintigraphic images were acquired for 500K counts per image over the total body with computer acquisition over the posterior thoracic and lumbar spine. Images were obtained on a wide field-of-view gamma camera two hours after injecting 15 mCi of Tc-99m MDP. Data analysis showed a significant reduction in the activity ratio of abnormal vertebral body to normal vertebral body in those patients treated with sodium fluoride (paired t-test p=0.0095). No significant change was observed in the control group of (p=0.142). These results suggest that sodium fluoride therapy promotes more rapid healing of osteoporotic vertebral fractures. They also demonstrate the utility of serial quantitative bone scintigraphy in assessing osteoporotic patients with vertebral compression fractures

  5. The electric field gradient in fluorides

    The electric quadrupole hyperfine interaction was investigated for various fluorides by the time-differential observation of the perturbed γ angular correlation and the Kern-Hanle effect of the 197 keV radiation of the 5/2+ level in 19F. This level was excited by inelastic proton scattering. The dependence of the quadrupole coupling constant from the chemical bond of the atom to its ligands was measured in fluorides of two-valid transition elements and in pureley covalent molecules, as (CF2)sub(n) or SF6. The influence of radiation-induced defects in nonmetals was investigated for cubic fluorides between 80 K and 1050 K. For CaF2 two different field gradients are obtained with coupling constants between 27 MHz and 3 MHz. By measurements of the angular distribution for CaF2/PrF3 mixed crystals which contain a variable concentration of F- interstitials was shown that the appearance of the 3 MHz frequency is correlated with the concentration of F- interstitials in CaF2. (BHO)

  6. Biological effects data: Fluoride and sulfur dioxide

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

    1975-04-01

    The Alumax Pacific Aluminum Corporation has proposed construction of an aluminum reduction facility near Youngs Bay at Warrenton, Oregon. This report comprises one part of the final report to Alumax on a research project entitled, Physical, Chemical and Biological Studies of Youngs Bay.'' It presents data pertaining to the potential biological effects of fluoride and sulfur dioxide, two potentially hazardous plant-stack emissions, on selected aquatic species of the area. Companion volumes provide a description of the physical characteristics the geochemistry, and the aquatic animals present in Youngs Bay and adjacent ecosystems. An introductory volume provides general information and maps of the area, and summarizes the conclusions of all four studies. The data from the two phases of the experimental program are included in this report: lethal studies on the effects of selected levels of fluoride and sulfur dioxide on the survival rate of eleven Youngs Bay faunal species from four phyla, and sublethal studies on the effects of fluoride and sulfur dioxide on the rate of primary production of phytoplankton. 44 refs., 18 figs., 38 tabs.

  7. Studies on fluoride complexing of hexavalent actinides using a fluoride ion selective electrode

    Complex formation between actinide(VI) and fluoride ions in aqueous solutions was investigated using a fluoride ion selective electrode (F-ISE). As fairly high acidity used to suppress hydrolysis of the actinide(VI) ions, significant liquid junction potentials (Esub(j)) existed in the system. An iterative procedure was developed for computing free hydrogen ion concentration [Hsup(+)] as it colud not be measured directly, using data obtained with F-ISE. Esub(j) values were estimated from known [Hsup(+)] and the stability constants of fluoride complexes of actinide(VI) ions were calculated following King and Gallagher's method using a computer program. The stability constants were found to follow the order U(VI)>Np(VI)>Pu(VI). (author)

  8. A health risk assessment for fluoride in Central Europe

    Fordyce, Fiona; Vrana, K.; Zhovinsky, E.; Povoroznuk, V.; Toth, G.; Hope, B.C.; Iljinsky, U.; Baker, J.

    2007-01-01

    Like many elements, fluorine (which generally occurs in nature as fluoride) is beneficial to human health in trace amounts, but can be toxic in excess. The links between low intakes of fluoride and dental protection are well known; however, fluoride is a powerful calcium-seeking element and can interfere with the calcified structure of bones and teeth in the human body at higher concentrations causing dental or skeletal fluorosis. One of the main exposure routes is via drinking water and the ...

  9. Use of professionally administered topical fluorides in Asia

    Tenuta, LMA; Fox, CH; Lo, ECM

    2012-01-01

    Professionally applied topical fluoride varnish, gel, and solution have been shown to be effective in preventing and in arresting dental caries. Their use in different countries in Asia varies greatly and may not correlate with the dental caries situation of the populations in the countries. In the higher-income countries, use of fluoride varnish and gel is common among dental professionals. In contrast, the use of professionally administered topical fluorides is not common in the lower-incom...

  10. The status of community water fluoridation in the United States.

    Easley, M W

    1990-01-01

    Community water fluoridation has served the American public extremely well as the cornerstone of dental caries prevention activities for 45 years. The dental and general health benefits associated with the ingestion of water-borne fluorides have been well known by researchers for an even longer period. Continued research has repeatedly confirmed the safety, effectiveness, and efficiency of community water fluoridation in preventing dental caries for Americans regardless of age, race, ethnicit...

  11. Sodium fluoride influences the expression of keratins in cultured keratinocytes

    Prado, Euridice; Wurtz, Tilmann; Ferbus, Didier; Shabana, El-Hassan; FOREST, Nadine; Berdal, Ariane

    2010-01-01

    Epithelia in lung, skin, and kidney are often exposed to fluoride, and tissue damage in lung and kidney due to fluoride is well documented. Nevertheless, the biological effects of fluoride on epithelia are poorly investigated. In the present study, we report effects of sodium fluoride (NaF) on the differentiation of a human epithelial cell line, HaCaT. These cells may serve as a keratinocyte model, because they express a wide spectrum of keratins (Ks), and they associate into stratified tissu...

  12. Effects of oral doses of fluoride on nestling European starlings

    Fleming, W.J.; Grue, C.E.; Schuler, C.A.; Bunck, C.M.

    1987-01-01

    Nestling European starlings (Sturnus vulgaris), raised and fed by free-living adults, were given daily oral doses of either distilled water, 193 mg sodium as Na2CO3 per kg of body weight (sodium control group), or 6, 10, 13, 17,23, 30, 40, 80, 160 mg of the fluoride ion as NaF in distilled water per kg of body weight (mg/kg). Dosing began when nestlings were 24-48 hr old and continued for 16 days. The 24-hr LD50 of fluoride for day-old starlings was 50 mg/kg. The 16-day LD50 was 17 mg/kg. The sodium control group did not differ from the water control group with respect to any of the measured variables. Growth rates were significantly reduced in the 13 and 17 mg of fluoride/kg groups; weights of birds given higher dose levels were omitted from growth comparisons because of high, fluoride-induced mortality. Although pre-fledging weights for the 10, 13, and 17 mg of fluoride/kg groups averaged 3.6 to 8.6% less than controls at 17 days, this difference was not significant. Feather and bone growth of the fluoride and control groups were not different, except for keel length measured at 17 days of age which averaged less in the fluoride groups. Liver and spleen weights were not affected by fluoride treatments. No histological damage related to fluoride treatments was found in liver, spleen, or kidney. The logarithm of bone fluoride and magnesium concentration increased with the logarithm of increasing fluoride treatment levels and were significantly correlated with each other. Fluoride treatments had no effect on percent calcium or phosphorus in bone or plasma alkaline phosphatase activity. Oral doses of fluoride appear to be more toxic than equivalent dietary levels. Most birds probably acquire fluoride through their diet. Therefore, the results of the study may overestimate the potential effects of fluorides on songbirds living in fluoride-contaminated environments.

  13. Oxidative stress in cases of chronic fluoride intoxication

    Ailani, Vinita; R. C. Gupta; Gupta, Sunil Kumar; Gupta, Kapil

    2009-01-01

    This study was conducted to find out the level of oxidative stress and effect of supplementation of vitamin C, D and Calcium on levels of SOD, serum and urinary fluoride in children residing in endemic fluorosis area. For this the fluoride belt of Jaipur district was selected. The parameters selected were Super oxide dismutase, serum fluoride and urinary fluoride. The study was conducted on one hundred children, selected from four areas (25 from each area) consuming water containing 1.2, 2.4,...

  14. Total Fluoride Intake and Urinary Excretion in German Children Aged 3–6 Years

    Haftenberger, Marjolein; Viergutz, Gabriele; Neumeister, Volker; Hetzer, Gisela

    2014-01-01

    There have only been few investigations comparing total fluoride intake and the fluoride proportion excreted in urine in pre–school children. In addition, the results of available studies are conflicting. Total fluoride intake was assessed in 11 healthy children aged 3–6 years on 2 consecutive days and urinary fluoride excretion was determined. The duplicate–diet approach was used for the assessment of fluoride intake from solid and liquid foods. Fluoride intake from toothbrushing was calcula...

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

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

    2015-01-01

    An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taki...

  16. Scientific Opinion on Dietary Reference Values for fluoride

    EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA

    2013-08-01

    Full Text Available Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA derived Dietary Reference Values (DRVs for fluoride, which are provided as Adequate Intake (AI from all sources, including non-dietary sources. Fluoride is not an essential nutrient. Therefore, no Average Requirement for the performance of essential physiological functions can be defined. Nevertheless, the Panel considered that the setting of an AI is appropriate because of the beneficial effects of dietary fluoride on prevention of dental caries. The AI is based on epidemiological studies (performed before the 1970s showing an inverse relationship between the fluoride concentration of water and caries prevalence. As the basis for defining the AI, estimates of mean fluoride intakes of children via diet and drinking water with fluoride concentrations at which the caries preventive effect approached its maximum whilst the risk of dental fluorosis approached its minimum were chosen. Except for one confirmatory longitudinal study in US children, more recent studies were not taken into account as they did not provide information on total dietary fluoride intake, were potentially confounded by the use of fluoride-containing dental hygiene products, and did not permit a conclusion to be drawn on a dose-response relationship between fluoride intake and caries risk. The AI of fluoride from all sources (including non-dietary sources is 0.05 mg/kg body weight per day for both children and adults, including pregnant and lactating women. For pregnant and lactating women, the AI is based on the body weight before pregnancy and lactation. Reliable and representative data on the total fluoride intake of the European population are not available.

  17. Irradiation effects on microhardness of fluoridated and non-fluoridated bovine dentin

    The objective of this study was to evaluate the effects of irradiation on microhardness of dentin. Dentin blocks from the cervical region of bovine incisors were treated as follows: 1) no irradiation; 2) irradiation of specimens up to 60 Gy (2Gy/day, 5 days/week); 3) no irradiation, but fluoridation of specimens for 5 min/d; 4) irradiation of specimens and daily fluoridation. Knoop hardness number (KHN) of the control specimens was 62.63±14.75 (mean±SD). This was significantly different from the irradiated dentin samples (8.74±2.59 KHN). Hardness of the fluoridated dentin specimens was 11.19±1.95 KHN in the non-irradiated group and 10.03±2.75 KHN in the irradiated groups, respectively. Within the limitations of an in vitro study, it is concluded that dentin is severely affected by irradiation. This could be an explanation for the frequently observed side-effects of irradiation like loss of enamel, gap formation at the amelodentinal junction, and caries of the cervical region. Fluoridation with acidic gels decereases microhardness of dentin surface, and does not prevent softening due to radiation, when saliva is absent. (au)

  18. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO2 and tetroxide RuO4. Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO4 with CIF3 enabled us to prepare chloryl hexafluororuthenate (V), CIO2+ RuF6-, a new compound well identified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF2 with RuO4 gave the oxide tetrafluoride RuOF4, the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (700C) of RuOF4 is presumably RuF4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF2 with RuO2 probably leads to the formation of the new oxide fluoride RuO2F4. Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds

  19. Synthesis and characterization of ruthenium fluorides and oxide fluorides with high oxidation states

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO2 and tetroxide RuO4. Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO4 with CIF3 enabled us to prepare chloryl hexafluororuthenate (V), ClO2+ RuF6-, a new compound well idendified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF2 with RuO4 gave the oxide tetrafluoride RuOF4, the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (700C) of RuOF4 is presumably RuF4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF2 with RuO2 probably leads to the formation of the new oxide fluoride RuO2F4. Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds

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

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

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

  1. CAN FLUORIDATION AFFECT LEAD (II) IN POTABLE WATER? HEXAFLUOROSILICATE AND FLUORIDE EQUILIBRIA IN AQUEOUS SOLUTION

    Recent reports have attempted to show that fluoridating potable water is linked to increased levels of lead(II) in the blood. We examine these claims in light of the established science and critically evaluate their significance. The completeness of hexafluorosilicate hydrolysi...

  2. Optical restoration of irradiated lead fluoride crystals

    Due to its relatively high resistance to high radiation, lead fluoride (PbF2) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF2 crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF2 samples with 1.1 and 1.3 MeV γs from 60Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410 - 450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF2 samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching

  3. Optical restoration of irradiated lead fluoride crystals

    Due to its relatively high resistance to high radiation, lead fluoride (PbF2) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF2 crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF2 samples with 1.1 and 1.3 MeV γs from 60Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410 - 450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF2 samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching. (author)

  4. Optical Restoration of Lead Fluoride Crystals

    Due to its relatively high resistance to high radiation, lead fluoride (PbF2) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF2 crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF2 samples with 1.1 and 1.3 MeV gammas from 60Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410-450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF2 samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching.

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

    Solovyov, Vyacheslav; Wiesmann, Harold

    2009-11-24

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

  6. Fluoride and children's intelligence: a meta-analysis.

    Tang, Qin-Qing; Du, Jun; Ma, Heng-Hui; Jiang, Shao-Jun; Zhou, Xiao-Jun

    2008-01-01

    This paper presents a systematic review of the literature concerning fluoride that was carried out to investigate whether fluoride exposure increases the risk of low intelligence quotient (IQ) in China over the past 20 years. MEDLINE, SCI, and CNKI search were organized for all documents published, in English and Chinese, between 1988 and 2008 using the following keywords: fluorosis, fluoride, intelligence, and IQ. Further search was undertaken in the website www.fluorideresearch.org because this is a professional website concerning research on fluoride. Sixteen case-control studies that assessed the development of low IQ in children who had been exposed to fluoride earlier in their life were included in this review. A qualitative review of the studies found a consistent and strong association between the exposure to fluoride and low IQ. The meta-analyses of the case-control studies estimated that the odds ratio of IQ in endemic fluoride areas compared with nonfluoride areas or slight fluoride areas. The summarized weighted mean difference is -4.97 (95%confidence interval [CI] = -5.58 to -4.36; p < 0.01) using a fixed-effect model and -5.03 (95%CI = -6.51 to 3.55; p < 0.01) using a random-effect model, which means that children who live in a fluorosis area have five times higher odds of developing low IQ than those who live in a nonfluorosis area or a slight fluorosis area. PMID:18695947

  7. Fluoride uptake from restorative dental materials by human enamel

    The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials ; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19F (p, αγ) 16O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts 106. All materials, except the composite, increased clearly the fluoride content of the underlying enamel. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel. (author)

  8. Computational investigation of the role of fluoride in Tamao oxidations

    Mader, Mary M.; Norrby, Per-Ola

    2002-01-01

    The Tamao oxidation of alkoxysilanes was investigated computationally to determine the role of fluoride. a key additive. in this reaction. A sequence of fluoride equilibria as well as possible transition states. mediated by basic and neutral peroxide, respectively, were examined, and a potential...

  9. Fluoride Analysis. Training Module 5.200.2.77.

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with fluoride analysis procedures. Included are objectives, an instructor guide, student handouts, and a list of reference material. This module considers the determination of fluoride in water supplies using the SPANDS and electrode…

  10. Fluoride inhibits the response of bone cells to mechanical loading

    H.M.E. Willems; E.G.H.M. van den Heuvel; S. Castelein; J. Keverling Buisman; A.L.J.J. Bronckers; A.D. Bakker; J. Klein-Nulend

    2011-01-01

    The response of bone cells to mechanical loading is mediated by the cytoskeleton. Since the bone anabolic agent fluoride disrupts the cytoskeleton, we investigated whether fluoride affects the response of bone cells to mechanical loading, and whether this is cytoskeleton mediated. The mechano-respon

  11. Calculation of vapor pressure of fission product fluorides and oxyfluorides

    The equilibrium diagrams of the condensed phases - solid and liquid - and vapor phase are collected for the principal fluorides and oxyfluorides of fission product elements (atomic number from 30 to 66). These diagrams are used more particularly in fuel reprocessing by fluoride volatility process. Calculations and curves (vapor pressure in function of temperature) are processed using a computer program given in this report

  12. Electrorecovery of tantalum in molten fluorides

    Considering the privileged situation of Brazil as a productor of tantaliferous minerals, the authors have in view the development of a technology for production of metallic tantalum via molten salts electrolysis; this has the advantage of improving the aggregate value of exportation products, additionally to tantalum oxide and tantalum concentrates. Having in view the preliminary determintion of better conditions of temperature, electrolyte composition and current density for this process, electrolysis were conducted with a solvent composed of an eutetic mixture of lithium, sodium and potassium fluoride for dipotassium fluotantalate and occasionally for tantalum oxide. Current efficiencies as high as 83% were obtained in favoured conditions. (author)

  13. LUMINESCENCE IN POTENTIAL FLUORIDE GLASS LASERS

    Jørgensen, C.

    1987-01-01

    Fluoride glasses of the zirconium barium lanthanide type (invented Rennes, 1975) and lead gallium zinc (or manganese) type (invented Le Mans, 1979) show luminescence of lanthanide J-Levels situated at least 2000 cm-1 above the closest lower level (this limit is a few times larger in most other materials). Not only is the non-radiative de-excitation as weak as incrystalline LaF3 (studied by Weber) but energy transfer between neodymium and ytterbium (III), or from manganese (II), and to some ex...

  14. Fluoride microresonators for mid-IR applications

    Grudinin, Ivan S; Yu, Nan

    2016-01-01

    We study crystalline fluoride microresonators for mid-infrared applications. Whispering gallery mode resonators were fabricated with BaF$_2$, CaF$_2$ and MgF$_2$ crystals. The quality factors were measured at wavelengths of 1.56 {\\mu}m and 4.58 {\\mu}m. The impacts of fabrication technique, impurities, multiphonon absorption and surface water are investigated. It is found that MgF2 resonators have room temperature Q factor of $8.3\\times 10^6$ at wavelength of 4.58 {\\mu}m, limited by multiphonon absorption.

  15. Fluoride use in Controlling Dental Caries and Fluorosis

    Gaurav Solanki

    2012-07-01

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

  16. KINETICS OF SORPTION OF FLUORIDE ON CALCINED MAGNESITE IN BATCH

    Singano, J. J.; Mashauri, D. A.; Mtalo, F. W.;

    1997-01-01

    on first-order reaction with respect to the concentration of fluoride. The rate constant is directly proportional to the dosage. The model takes into accounts the lag time observed. The kinetical model can be described for any given dosage and initial fluoride concentration in the water. The reaction...... rate parameter, K, varies however slightly for different initial concentrations of fluoride in the water and different dosage of calcined magnesia. These relationships are described separately by two linear equations. It is discussed that the observed lag time is due to the fact that magnesia cannot......A series of sorption of fluoride on calcined magnesite are obtained from thermostatic pH-chemostat and jar test experiments. The fluoride removal is observed not to start instantly, as normal, but after a lag time of up to ½ an hour of contact time. A model for sorption kinetics is developed, based...

  17. Milk fluoridation for the prevention of dental caries

    Jolán Bánóczy

    2013-11-01

    Full Text Available The aim of this review is to give an overview of 55 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization which began in the early 1980s. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in various types of milk. Clinical trials were initiated in the 1980s – some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programmes. Conclusion. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. The amount of fluoride added to milk depends on background fluoride exposure and age of the children: commonly in the range 0.5 to 1.0 mg per day. An advantage of the method is that a precise amount of fluoride can be delivered under controlled conditions. The cost of milk fluoridation programmes is low, about € 2 to 3 per child per year. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk programme.

  18. Caries prevention through the fluoridation of milk. A review.

    Bánóczy, Jolán; Rugg-Gunn, Andrew J

    2007-10-01

    The aim of this review is to give an overview of 50 years experience of milk fluoridation and draw conclusions about the applicability of the method. Fluoridated milk was first investigated in the early 1950s, almost simultaneously in Switzerland, the USA and Japan. Stimulated by the favourable results obtained from these early studies, the establishment of The Borrow Dental Milk Foundation (subsequently The Borrow Foundation) in England gave an excellent opportunity for further research, both clinical and non-clinical, and a productive collaboration with the World Health Organization from the early 1980s onwards. Numerous peer-reviewed publications in international journals showed clearly the bioavailability of fluoride in milk, and increased concentrations of fluoride in saliva, dental plaque, dental enamel and dentine, and urine, after consumption of fluoridated milk. Clinical trials were initiated in the 1980s--some of these can be classed as randomised controlled trials, while most of the clinical studies were community preventive programs. These evaluations showed clearly that the optimal daily intake of fluoride in milk is effective in preventing dental caries. At present, milk fluoridation programs are running continuously in about ten countries of the world. Fluoridation of milk can be recommended as a caries preventive measure where the fluoride concentration in drinking water is suboptimal, caries experience in children is significant, and there is an existing school milk program. The program should aim to provide fluoridated milk for at least 200 days per year and should commence before the children are 4 years of age. PMID:18078140

  19. Fluoride-induced disruption of reproductive hormones in men

    Fluoride-induced reproductive effects have been reported in experimental models and in humans. However, these effects were found in heavily exposed scenarios. Therefore, in this work our objective was to study reproductive parameters in a population exposed to fluoride at doses of 3-27 mg/day (high-fluoride-exposed group--HFEG). Urinary fluoride levels, semen parameters, and reproductive hormones in serum (LH, FSH, estradiol, prolactin, inhibin-B, free and total testosterone) were measured. Results were compared with a group of individuals exposed to fluoride at lower doses: 2-13 mg/day (low-fluoride-exposed group-LFEG). A significant increase in FSH (P<0.05) and a reduction of inhibin-B, free testosterone, and prolactin in serum (P<0.05) were noticed in the HFEG. When HFEG was compared to LFEG, a decreased sensitivity was found in the FSH response to inhibin-B (P<0.05). A significant negative partial correlation was observed between urinary fluoride and serum levels of inhibin-B (r=-0.333, P=0.028) in LFEG. Furthermore, a significant partial correlation was observed between a chronic exposure index for fluoride and the serum concentrations of inhibin-B (r=-0.163, P=0.037) in HFEG. No abnormalities were found in the semen parameters studied in the present work, neither in the HFEG, nor in the LFEG. The results obtained indicate that a fluoride exposure of 3-27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs

  20. Hydrogen Fluoride in the Local Universe

    Monje, Raquel R.; Lis, Dariusz C.; Phillips, Thomas G.

    2015-01-01

    The Herschel Space Observatory has provided a unique opportunity to study hydride molecules with large rotational constant in the interstellar medium (ISM) within the nearby universe. Some of the key results from hydride studies with Herschel, and in particular with the Heterodyne Instrument for the Far-Infrared (HIFI), are the first detection at high spectral resolution of the fundamental J = 1 - 0 rotational transition of hydrogen fluoride (HF) at 1.232 THz, and the discovery of its ubiquitous nature within the ISM of the Milky Way galaxy and nearby galaxies. The remarkable Herschel/ HIFI results suggest, that the HF J = 1 - 0 transition promises to yield an extremely sensitive probe of the diffuse molecular gas along the lines of sight toward background far-infrared continuum sources and, as predicted earlier by chemical models, a valuable surrogate for molecular hydrogen in the nearby and high redshift universe. These and other interesting results on hydrogen fluoride from Herschel observations will be presented, as well as the results from follow-up studies from ground-base facilities on hydride molecules towards luminous lensed high-redshifted galaxies with strong submillimeter continuum.

  1. Polyvinylidene fluoride - a polymer as transducer material

    Polyvinylidene fluoride or PVDF is a flexible, thin piezo film and long chain semicrystalline polymer containing repeated of CH/sub 2/ - CH/sub 2/. In order to obtain desired piezoelectric properties PVDF is poled by subjecting it to high electric field. In poled PVDF piezoelectric constants have different values for each axis and one constant per axis. PVDF polymer exhibits generator and motor action. Usually 1000 A /sup o/ thick vacuum-deposited aluminum electrodes are formed on both sides of the sheet. Polymer material of PVDF can be used as a sensing element with temperature range of -40 /sup 0/ C to 100 /sup 0/C and a frequency range of 10/sup -3/ to 10/sup -9/ Hz. This paper includes as experimental observation of exciting aluminium open-ended tube at its resonance using PVDF transducer and maintained in this condition using phase lock loop or PLL. The tube is free to resonate when 9-micrometer thin polyvinylidene fluoride transducer is energized. It is observed that a film of such material can easily be used to produced the requisite vibrations in the tube. (author)

  2. Lanthanum fluoride nanoparticles for radiosensitization of tumors

    Kudinov, Konstantin; Bekah, Devesh; Cooper, Daniel; Shastry, Sathvik; Hill, Colin; Bradforth, Stephen; Nadeau, Jay

    2016-03-01

    Dense inorganic nanoparticles have recently been identified as promising radiosensitizers. In addition to dose enhancement through increased attenuation of ionizing radiation relative to biological tissue, scintillating nanoparticles can transfer energy to coupled photosensitizers to amplify production of reactive oxygen species, as well as provide UVvisible emission for optical imaging. Lanthanum fluoride is a transparent material that is easily prepared as nanocrystals, and which can provide radioluminescence at a number of wavelengths through simple substitution of lanthanum ions with other luminescent lanthanides. We have prepared lanthanum fluoride nanoparticles doped with cerium, terbium, or both, that have good spectral overlap with chlorine6 or Rose Bengal photosensitizer molecules. We have also developed a strategy for stable conjugation of the photosensitizers to the nanoparticle surface, allowing for high energy transfer efficiencies on a per molecule basis. Additionally, we have succeeded in making our conjugates colloidally stable under physiological conditions. Here we present our latest results, using nanoparticles and nanoparticle-photosensitizer conjugates to demonstrate radiation dose enhancement in B16 melanoma cells. The effects of nanoparticle treatment prior to 250 kVp x-ray irradiation were investigated through clonogenic survival assays and cell cycle analysis. Using a custom apparatus, we have also observed scintillation of the nanoparticles and conjugates under the same conditions that the cell samples are irradiated.

  3. Luminescence in potential fluoride glass lasers

    Fluoride glasses of the zirconium barium lanthanide type (invented Rennes, 1975) and lead gallium zinc (or manganese) type (invented Le Mans, 1979) show luminescence of lanthanide J-Levels situated at least 2000 cm-1 above the closest lower level (this limit is a few times larger in most other materials). Not only is the non-radiative de-excitation as weaK as in crystalline LaF3 (studied by Weber) but energy transfer between neodymium and ytterbium(III), or from manganese(II), and to some extent from chromium(III), to luminescent J-levels of neodymium(III), erbium(III) and thullium(III) is highly efficient even at low concentrations. One advantage for laser applications is that the lowest quartet state of manganese(II) has a life-time 10 to 15 milliseconds (like in many phosphate glasses and crystalline compounds) allowing energy transfer, extending by huge factors the average life-time of the emitting J-levels. Though the tera-watt lasers (Livermore, California, 1978) inducing deuterium-tritium fusion are silicate glass containing neodymium(III), fluoride glasses should be preferable for many purposes. The evaluation of laser parameters from small-scale experimentation is feasible

  4. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium

    Neetu Tyagi; Epsita Ghanti; Nikesh Gupta; N P Lalla; Rajamani Nagarajan

    2009-12-01

    Synthesis of mixed metal fluorides of the general formula, KMF3 (M = Mg, Mn, Co, Ni, Cu and Zn), possessing perovskite structure was investigated in non-aqueous medium. The fluorides were characterized by powder X-ray diffraction, FT–IR spectroscopy, thermal analysis, SEM and TEM. Monophasic cubic phases were obtained for the central metal ions such as Mg, Mn, Co, Ni, and Zn and a tetragonally distorted phase was observed for Cu. The usage of non-aqueous medium is advantageous for the bulk synthesis of these fluorides, since it eliminated the generation and handling of the hazardous HF that has usually been encountered during aqueous preparations. The average crystallite size of the fluorides obtained by this approach was estimated to be in the range of 9–30 nm. SEM micrographs of KZnF3 showed cubic morphology of perovskite phases. TEM studies on KCuF3 confirmed the presence of tetragonal distortion. The fluoride content was determined by titrimetry and found to be nearly stoichiometric. Some of these fluorides were found to be thermally stable up to 225°C in air. These fluorides were employed as fluorinating agents in organic fluorination reactions, thereby suggesting their possible utilization for selective fluorination of aliphatic and aromatic hydrofluorocarbons (HFCs) that are industrially relevant.

  5. Fluoride Levels of Mothers' Breast Milk in Egypt

    Ghada, Z A Soliman and Tamer M M Saad

    2012-01-01

    Full Text Available Introduction: Fluoride exists naturally in water sources and is derived from fluorine. It is well known that fluoride helps, prevent and even reverse the early stages of tooth decay. Aim: The aim of the present study was to determine the fluoride levels in plasma and breast milk of lactating mothers in Egypt (Cairo and Giza Governorate. Material and Methods: Two hundred healthy lactating mothers aged between 20-40 years old were asked to give plasma and milk samples voluntary. Breast milk samples were directly refrigerated until measurements. The fluoride concentrations of plasma, milk and drinking tap water were assessed using an ion-selective fluoride electrode combined with an ion analyzer. Results: The fluoride levels of plasma, breast milk and drinking tap water samples were 0.0207±0.012, 0.0111±0.0044 ppm, and 0.482±0.117 ppm, respectively. A significant direct correlation between fluoride content in breast milk and drinking tap water was found (r=0.858, p< 0.01.

  6. Amelioration of Fluoride Toxicity with the Use of Indigenous Inputs

    Maitra A.

    2013-08-01

    Full Text Available An assessment was undertaken to study the efficacy of bacterial consortia isolated from different sources viz. rhizosphere of rice plant, oil spill sites of a petrol pump and from the sludge of a pharmaceutical waste water drain against the impact of fluoride. The experiments were conducted with two crops. In this mung bean experiment Vigna radiata was selected as a test crop. The seeds were sown in the field with bacterial consortia, compost and reduced dose (25% less nitrogen than recommended dose of chemical fertilizer. After 30days of seed sowing (DAS, plants were collected from the field and dipped into the sodium fluoride solution with different concentrations for 48 hours. Thereafter, the impact of fluoride on chlorophyll, sugar, proline and relative water content (% were evaluated. Scanning electron microscopy (SEM of the stem section was performed. SEM studies revealed that anatomical structure deformed with 1.5 mg/l sodium fluoride solution. It was observed that such treatment combination during the sowing of crops leads to combat the impact of lower doses of sodium fluoride (0.2 mg/l. Another experiment was also conducted within plastic pots with and without bacterial consortia isolated from rhizosphere of rice plant and oil spilled soil of petrol pump with the same field soil. Each pot was filled with 5 kg of soil + 2lt of water (on the basis of soil saturation. Oryza sativa seedlings were transplanted with different strength of sodium fluoride solution (25 mgNaF/kg, 50 mgNaF/kg, 100 mgNaF/kg and 500mgNaF/kg within the above pots. In second experiment, rice plants dried in all pots after 500 mgNaF/kg concentration of sodium fluoride. In this pot experiment bacterial strain are capable of reducing fluoride content in soil as noted by measuring fluoride in the pot soil after the experiment.

  7. Fluoride and lead adsorption on carbon nanotubes

    WANG Shuguang; LI Yanhui

    2004-01-01

    The properties and applications of CNT have been studied extensively since Iijima discovered them in 1991[1,2]. They have exceptional mechanical properties and unique electrical property, highly chemical stability and large specific surface area. Thus far, they have widely potential applications in many fields. They can be used as reinforcing materials in composites[3], field emissions[4], hydrogen storage[5], nanoelectronic components[6], catalyst supports[7], adsorption material and so on. However, the study on the potential application of CNT, environmental protection field in particular, was hardly begun.Long[8] et al. reported that CNT had a significantly higher dioxin removal efficiency than that of activated carbon. The Langmuir adsorption constant is 2.7 × 1052, 1.3 × 1018 respectively. The results indicated that CNT is potential candidate for the removal of micro-organic pollutants. However, the reports on the CNT used as fluoride and heavy metal adsorbent are seldom.In this paper, A novel material, alumina supported on carbon nanotubes (Al2O3/CNT), was prepared from carbon nanotubes and Al(NO3)3. X-ray diffraction (XRD) spectra demonstrate that alumina is amorphous, and scanning electron microscope (SEM) images show that CNT and alumina are homogeneously mixed. Furthermore, the fluoride adsorption behavior on the surface of Al2O3/CNT has been investigated and compared with other adsorbents. The results indicate that Al2O3/CNT has a high adsorption capacity, with a saturation adsorption capacity of 39.4 mg/g. It is also found that the adsorption capacity of Al2O3/CNT is 3.0~4.5 times that of γ-Al2O3while almost equal to that of IRA-410 polymeric resin at 25 ℃. The adsorption isotherms of fluoride on Al2O3/CNT is fit the Freundlich equation well, optimal pH ranging from 5.0 to 9.0.Also in this paper, a novel material, modified carbon nanotubes (CNT), was prepared from carbon nanotubes and HNO3 under boiling condition. Infrared spectroscopy (IR

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

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

    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 preventi...

  9. Separation of volatile fluorides by selective desorption from granular inorganic fluorides

    Problems posed by the theory of gas mixtures separation by the method of selective desorption of components as applied to purification of uranium hexafluoride from some volatile impurity fluorides, i.e. WF6, MoF6, HF, are stated. Examples of calculation of WF6 - MoF6 mixture separation factor, as well as of composition of MoF6 stripping, depending on the composition of the initial WF6 - MoF6 mixture, are provided

  10. Fluoride reactions with dental enamel following different forms of fluoride supply

    The reactions with dental enamel of NaF as tablets dissolved in different beverages or supplied with NaCl, simulating domestic salt fluoridation, were studied in tests with enamel surfaces and enamel powder. It was confirmed that powdered enamel can react quite differently from enamel surfaces under certain conditions. Enamel surfaces took up much more fluoride (F) from orange juice than from water or milk, and neither the low pH nor the citrate content of the juice increased the formation of unstable CaF2 in the enamel, as judged from a KOH leaching test. The F uptake by enamel surfaces from 0.25 mM NaF in 175 mM NaCl, corresponding to a dish prepared with salt containing 500 parts/106 F, was about 80 percent greater than from the same NaF concentration in water. This NaCl concentration did not increase the formation of CaF2 in the enamel, as judged from the KOH test, while 350 mM NaCl caused a moderate increase. The investigations support the administration of NaF tablets with orange juice and the plans for domestic salt fluoridation. (author)

  11. Determination of fluoride with thorium nitrate by catalytic titration

    Amperometry, constant-current potentiometry and spectrophotometry were used to follow the course of catalytic titrations of fluoride and silicofluoride with thorium nitrate. The hydrogen peroxide-iodide system was used as the indicator reaction. Titrations were performed in 50% ethanolic acetate buffer, pH 3.6. Amounts of 3.70 to 6.85 mg of ammonium fluoride, 5.53 to 10.79 mg of potassium fluoride and 4.34 to 8.41 mg of sodium silicofluoride were determined with a maximum average deviation of 0.9%. The results obtained are in good agreement with those of comparable methods. (author)

  12. Spectrophotometric determination of fluorides in water with Hach equipment

    The spectrophotometric method for the determination of the fluoride ion in water, demineralized water, raw waters, laundry waters and waters treated with ion exchange resins , using the technique and the SPADNS coloring indicated in the operation manual of the Hach equipment is described. This method covers the determination of the fluoride ion in the range from 0 to 2 mg/l on 25 ml. of radioactive base sample. These limits can be variable if the size of the used aliquot one is changed for the final determination of the fluoride ion. (Author)

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

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

    2011-09-28

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

  14. Graphene Fluoride: A Stable Stoichiometric Graphene Derivative and its Chemical Conversion to Graphene

    Zbořil, Radek; Karlický, František; Bourlinos, Athanasios B.; Steriotis, Theodore A.; Athanasios K. Stubos; Georgakilas, Vasilios; Šafářová, Klára; Jančík, Dalibor; Trapalis, Christos; Otyepka, Michal

    2010-01-01

    Stoichoimetric graphene fluoride monolayers are obtained in a single step by the liquid-phase exfoliation of graphite fluoride with sulfolane. Comparative quantum-mechanical calculations reveal that graphene fluoride is the most thermodynamically stable of five studied hypothetical graphene derivatives; graphane, graphene fluoride, bromide, chloride, and iodide. The graphene fluoride is transformed into graphene via graphene iodide, a spontaneously decomposing intermediate. The calculated ban...

  15. Solubility of fluorides of alkaline earth metals and some rare earths in anhydrous trifluoroacetic acid

    Solubility of fluorides of alkaline earth and some rare earth metals in anhydrous trifluoroacetic acid is studied. For each type of fluoride solubility depends on the ionic radius of the cation. Solubility of fluorides of alkaline earth metals grows from magnesium to barium. All the fluorides in anhydrous trifluoroacetic acid form solvates. Solvates of strontium and scandium fluorides are shown to decompose at 110 and 150 deg C respectively

  16. Evaluation of efficacy caries prevent of stabilized fluoride dentifrices in students of medical university

    Марченко, Наталья Сергеевна; Політун, Антоніна Михайлівна; Терешина, Тетяна Петрівна

    2015-01-01

    Conducted laboratory and clinical evaluation of the efficacy of  stabilized fluoride dentifrice compared to without fluoride dentifrice, for the prevention of dental caries in students. Indexes stability of fluoride in dentifrice containing fluoride , concentration and  prolonged action ionized fluoride in saliva for the prevention of dental caries.Methods: Clinical and laboratory testing of dentifrice in vivo and in vitro research.Results: In clinical and laboratory testing of caries prevent...

  17. Change in fluoride content of Maltese tapwaters : implications for oral health

    Vella, Alfred J.; Borg, Vincent

    1989-01-01

    Dietary intake of fluoride is believed to be largely derived from drinking water. In Malta, tap water presently contains less fluoride than is found in naturally occurring ground water obtained from aquifers. Over 55% of water production comes from reverse osmosis and such water is practically fluoride-free. Before the introduction of reverse osmosis water into the water budget, fluoride levels measured from 10 different tap waters averaged 0.51 ppm F-. Now, fluoride content measured from 19 ...

  18. Determination of fluoride content in toothpaste using spectrophotometry

    Susanti Pudji Hastuti

    2013-09-01

    Full Text Available Background: Intake excessive fluoride in children’s teeth are generally marked with white and brown patches. Excessive fluoride of more than 4.0 mg/L can cause a person suffering from poisoning, fragility of the bones (osteoporosis, liver and kidney damage. Knowledge about the spectrophotometry for determination method of fluoride content in commercially available toothpaste is very few. Purpose: The purposes of study were to examine the suitable method for fluoride extraction and to determine out the accuracy, precision, linearity, and stability of the measurement method of fluoride content in toothpaste. Methods: The suitable F extraction method was determined by the comparison among 3 methods of extraction; e.g. the dried samples were immersed in (1 distilled water, (2 96% HCl, and (3 96% HNO3; and the validation methods of measurement were the maximum wavelength, standart curve, accuracy test, precision test, and stability test. Results: Result showed that the fluoride extraction by using the concentrated HNO3 was found to have the highest levels of fluoride, followed by hydrochloric acid dissolution (HCl and distilled water, while the method of validation showed that SPADNS revealed the acceptable accuracy. Precision has the RSD ≤ 2.00%. Furthermore the stability test result showed that the measurement of fluoride less than 2 hours was still reliable. Conclusion: The study suggested that the best result of fluoride extraction from toothpaste could be gained by using concentrate HNO3, and the spectrophotometer (UV-Vis Mini Shimadzu U-1240 and SPADNS have the acceptable accuracy.Latar Belakang: Pemasukan fluoride yang berlebihan pada gigi anak ditandai dengan bercak putih dan coklat. Fluoride lebih dari 4.0 mg / L dapat menyebabkan seseorang menderita keracunan , kerapuhan tulang (osteoporosis, kerusakan hati dan ginjal. Pengetahuan tentang spektrofotometri untuk metode penentuan kadar fluoride dalam pasta gigi yang tersedia secara

  19. Cerium fluoride crystals for calorimetry at LHC

    High-resolution homogeneous calorimetry is fully justified for part of the physics program at the Large Hadron Collider (LHC). The main design features of proposed CeF3 crystals for calorimetry for LHC are discussed. The severe constraints LHC imposes on detectors make the use of 'classical' crystals impossible. Therefore, a large R and D effort has been undertaken by the 'Crystal Clear' collaboration in order to find new, dense, fast and radiation hard crystals. A good candidate, cerium fluoride, has been identified and studied. It is interesting at this stage to review the specifications of scintillators for LHC and to see how well available data on CeF3 luminescence, decay time, light yield, optical transmission and resistance to radiation meet them. Milestones to reach before starting a large scale crystal production in view of the eventual construction of a calorimeter, are also discussed. (author) 15 refs., 15 figs., 1 tab

  20. Further results on cerium fluoride crystals

    A systematic investigation of the properties of cerium fluoride monocrystals has been performed by the 'Crystal Clear' collaboration in view of a possible use of such crystals for the construction of high precision electromagnetic calorimeters for the future generation of high luminosity accelerators. A large sample of different crystals grown by several producers has been studied. The spectroscopic characteristics, the transmission, luminescence and excitation spectra and the decay time curves are analysed. The light yield of the different crystals is measured with photomultipliers and Si photodiodes and compared to reference standards like BGO and NaI(Tl). The radiation damage behaviour is then presented for γ and neutron irradiations, at different doses and dose rates, including thermal and optical bleaching. (orig.)

  1. Further results on cerium fluoride crystals

    Anderson, S.; Auffray, E.; Aziz, T.; Baccaro, S.; Banerjee, S.; Bareyre, P.; Barone, L.E.; Borgia, B.; Boutet, D.; Burq, J.P.; Chemarin, M.; Chipaux, R.; Dafinei, I.; D' Atanasio, P.; De Notaristefani, F.; Dezillie, B.; Dujardin, C.; Dutta, S.; Faure, J.L.; Fay, J.; Ferrere, D.; Francescangeli, O.; Fuchs, B.A.; Ganguli, S.N.; Gillespie, G.; Goyot, M.; Gupta, S.K.; Gurtu, A.; Heck, J.; Herve, A.; Hillemanns, H.; Holdener, F.; Ille, B.; Joensson, L.; Kierstead, J.; Krenz, W.; Kway, W.; Le Goff, J.M.; Lebeau, M.; Lebrun, P.; Lecoq, P.; Lemoigne, Y.; Loomis, G.; Lubelsmeyer, K.; Madjar, N.; Majni, G.; El Mamouni, H.; Mangla, S.; Mares, J.A.; Martin, J.P.; Mattioli, M.; Mauger, G.J.; Mazumdar, K.; Mengucci, P.; Merlo, J.P.; Moine, B.; Nikl, N.; Pansart, J.P.; Pedrini, C.; Poinsignon, J.; Polak, K.; Raghavan, R.; Rebourgeard, P.; Rinaldi, D.; Rosa, J.; Rosowsky, A.; Sahuc, P.; Samsonov, V.; Sarkar, S.; Schegelski, V.; Schmitz, D.; Schneegans, M.; Seliverstov, D.; Stoll, S.; Sudhakar, K.; Sven; Crystal Clear Collaboration

    1993-08-15

    A systematic investigation of the properties of cerium fluoride monocrystals has been performed by the 'Crystal Clear' collaboration in view of a possible use of such crystals for the construction of high precision electromagnetic calorimeters for the future generation of high luminosity accelerators. A large sample of different crystals grown by several producers has been studied. The spectroscopic characteristics, the transmission, luminescence and excitation spectra and the decay time curves are analysed. The light yield of the different crystals is measured with photomultipliers and Si photodiodes and compared to reference standards like BGO and NaI(Tl). The radiation damage behaviour is then presented for [gamma] and neutron irradiations, at different doses and dose rates, including thermal and optical bleaching. (orig.)

  2. Chemical etching of polyvinylidene fluoride films

    The chemical etching of two types of polyvinylidene fluoride (PVDF) film irradiated with heavy ions was studied. Several etchants have been investigated in this work. It was found that for a solution of KOH+KMnO4 the radial etch rate (RER) is larger than for solutions used by other authors. This new solution for etching PVDF is used both for microfilter and for track detector purposes. Even alphas from a thick uranium foil register in solef PVDF by using this solution. As expected the RER for alphas is considerably lower than that for heavy ions. The diameter of the sandglass shaped pores at the surface of the film as a function of the etching time for various concentrations of KMnO4 and KOH and at different temperatures was measured. (author)

  3. Fluoridated toothpaste: usage and ingestion of fluoride by 4- to 6-yr-old children in England.

    Zohoori, Fatemeh V; Duckworth, Ralph M; Omid, Narges; O'Hare, William T; Maguire, Anne

    2012-10-01

    Fluoridated toothpaste is effective for dental caries control, yet may be a risk factor for dental fluorosis. This study aimed to quantify fluoride ingestion from toothpaste by children and to investigate the effects of age, gender, and social class on the amount of fluoride ingested per toothbrushing session. Sixty-one children, 4-6 yr of age, were recruited: 38 were from low socio-economic (LSE) areas of Newcastle, UK, and 23 were from high socio-economic (HSE) areas of Newcastle, UK. All expectorated saliva, rinse water (if used), and residual toothpaste were collected after brushing at home and were analysed for fluoride. Of the children, 74% and 69% from HSE and LSE areas, respectively, claimed that they brushed twice per day. The mean (SD) weight of toothpaste dispensed was 0.67 (0.36) g. The mean (SD) amount of fluoride ingested per toothbrushing session and per day was 17.0 (14.7) and 29.3 (32.8) μg kg(-1) of body weight, respectively. Daily fluoride intake per kilogram of body weight did not differ significantly between children from LSE and HSE areas. Fluoride intake per toothbrushing session was significantly influenced by weight of toothpaste, its fluoride concentration, and the child's age. Whilst the average amount of toothpaste used per toothbrushing session was more than twice the recommended amount (of 0.25 g), only one child had a daily fluoride intake that exceeded the tolerable upper intake level of 0.1 mg kg(-1) of body weight for this age group. PMID:22984999

  4. Using High Fluoride Concentration Products in Public Policy: A Rapid Review of Current Guidelines for High Fluoride Concentration Products.

    Douglas, Gail V A; Ramsdale, Martin P; Vinall-Collier, Karen; Csikar, Julia I

    2016-01-01

    Despite improvements in dental caries levels since the widespread introduction of fluoride toothpastes, it is still a disease which is considered to be a priority in many countries around the world. Individuals at higher risk of caries can be targeted with products with a high fluoride concentration to help reduce the amount and severity of the disease. This paper compares guidance from around the world on the use of products with a high fluoride concentration and gives examples of how guidance has been translated into activity in primary care dental practice. A rapid review of electronic databases was conducted to identify the volume and variation of guidance from national or professional bodies on the use of products with a high fluoride concentration. Fifteen guidelines published within the past 10 years and in English were identified and compared. The majority of these guidelines included recommendations for fluoride varnish use as well as for fluoride gels, while a smaller number offered guidance on high fluoride strength toothpaste and other vehicles. Whilst there was good consistency in recommendations for fluoride varnish in particular, there was sometimes a lack of detail in other areas of recommendation for other vehicles with a high fluoride concentration. There are good examples within the UK, such as the Childsmile project and Delivering Better Oral Health, which highlight that the provision of evidence-based guidance can be influential in directing scarce resources towards oral health improvements. Policy can be influenced by evidence-based national recommendations and used to help encourage dental professionals and commissioners and third-party payers to adopt higher levels of practices aimed at oral health improvement. PMID:27100106

  5. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Timothy A. DeVol

    2010-03-01

    Full Text Available This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

  6. Redox condition in molten fluoride salts Definition and control

    The loosely-used term 'redox condition' as applied to molten fluoride salts such as flibe is defined quantitatively as the fluorine potential. Several methods of controlling the property of the melt are discussed

  7. Physical and chemical properties of volatile ruthenium fluorides

    Available data are compiled published before 1977 on the preparation and the physical and chemical properties of ruthenium hexafluoride, ruthenium oxide tetrafluoride, ruthenium pentafluoride and ruthenium octa-fluoride. (author)

  8. Efficacy of silver diamine fluoride as an antibacterial as well as antiplaque agent compared to fluoride varnish and acidulated phosphate fluoride gel: An in vivo study

    Shalin Shah

    2013-01-01

    Full Text Available Background: Silver diamine fluoride (SDF is already proven as an antibacterial agent in vitro. Present study was formulated to compare the efficacy of SDF as an antibacterial as well as antiplaque agent in vivo with fluoride varnish and acidulated phosphate fluoride (APF gel. Study Design: Total 123 children (male = 82, female = 41 were included in the study for a period of 18 months. Children were divided into three different groups-Group 1: SDF; Group 2: fluoride varnish; and Group 3: APF gel. All subjects were evaluated via plaque score at 6 th , 12 th , and 18 th months as well as Streptococcus mutans counts in saliva at 72 h, 6 th , 12 th , and 18 th months of follow-up. Results: Significant reduction was found in plaque score as well as S. mutans counts irrespective of group division. On intergroup comparison, no statistically significant difference was found in plaque score, but significant reduction in S. mutans counts was found in Group 1 as compared with Groups 2 and 3, while no significant difference was found between Groups 2 and 3. Conclusion: In vivo application of SDF on enamel significantly decreases S. mutans counts as compared to fluoride varnish and APF gel.

  9. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    DeVol, Timothy A.; Basak Yazgan-Kukouz; Baris Kokuoz; DiMaio, Jeffrey R.; Kevin B. Sprinkle; James, Tiffany L.; Kucera, Courtney J.; Jacobsohn, Luiz G.; John Ballato

    2010-01-01

    This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE) doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP) that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminesc...

  10. Corrosion behavior of zirconia in acidulated phosphate fluoride

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

    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 charac...

  11. Corrosion behavior of zirconia in acidulated phosphate fluoride

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

    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 characteri...

  12. Fluoride Consumption and Its Impact on Oral Health

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

    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 (DM...

  13. Scientific Opinion on Dietary Reference Values for fluoride

    EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)

    2013-01-01

    Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for fluoride, which are provided as Adequate Intake (AI) from all sources, including non-dietary sources. Fluoride is not an essential nutrient. Therefore, no Average Requirement for the performance of essential physiological functions can be defined. Nevertheless, the Panel considered that the setting of an AI is appropriate because of the be...

  14. Thermodynamic investigation of fluoride salts for nuclear energy production

    Beilmann, Markus

    2013-01-01

    In this work thermodynamic properties of molten fluoride salts and salt mixtures are investigated. Fluoride salts have advantageous properties to be used in energy producing systems based on the conversion from heat to energy like i.e in Molten Salt Reactors. For this purpose it is very important to have detailed information about the heat capacity of the pure salts and salt mixtures. To get a better understanding about the heat capacity in mixtures drop calorimetry measurements of mixture...

  15. The economic value of Quebec’s water fluoridation program

    Tchouaket, Eric; Brousselle, Astrid; Fansi, Alvine; Dionne, Pierre Alexandre; Bertrand, Elise; Fortin, Christian

    2013-01-01

    Aim Dental caries is a major public health problem worldwide, with very significant deleterious consequences for many people. The available data are alarming in Canada and the province of Quebec. The water fluoridation program has been shown to be the most effective means of preventing caries and reducing oral health inequalities. This article analyzes the cost-effectiveness of Quebec’s water fluoridation program to provide decision-makers with economic information for assessing its usefulnes...

  16. Polyvinylidene fluoride based nanocomposites for the development of energy systems

    Pereira, J. Nunes

    2013-01-01

    The economic and environmental costs of current energy resources created the need to develop new methods to generate and store energy. In this sense, the development of polymer materials led to the emergence of a new generation of porous polymers for energy applications, which are typically described as “energy polymers”. The specific properties of poly(vinylidene fluoride) (PVDF) and its copolymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)), such as high diele...

  17. Quality of our groundwater resources: arsenic and fluoride

    Nordstrom, D. Kirk

    2011-01-01

    Groundwater often contains arsenic or fluoride concentrations too high for drinking or cooking. These constituents, often naturally occurring, are not easy to remove. The right combination of natural or manmade conditions can lead to elevated arsenic or fluoride which includes continental source rocks, high alkalinity and pH, reducing conditions for arsenic, high phosphate, high temperature and high silica. Agencies responsible for safe drinking water should be aware of these conditions, be prepared to monitor, and treat if necessary.

  18. Polyacrylamide supported SPADNS-zirconium resin for fluoride removal

    Fluoride contamination of groundwater, both anthropogenic and natural, is a major problem worldwide. In the present work a new adsorbent has been prepared by incorporating SPADNS (trisodium 2-parasulfophenylazo-1,8-dihydroxy-3,6-napthalenedisulfonate salt) into the acrylamide matrix. SPADNS was selected because it has strong complexating ability towards zirconium. The substrate was conditioned for selective fluoride ion sorption by forming zirconium complex with SPADNS. The adsorbent was characterized using FTlR and EDXRF analysis

  19. Electrochemistry of silicon in chloro-fluoride and carbonate melts

    Devyatkin S.V.

    2003-01-01

    Full Text Available The electrochemical behavior of K2SiF6 in chloro-fluoride melts and that of SiO2 in carbonate melts has been studied. Silicon, titanium silicides, boron silicide and ternary compounds Ti-Si-B have been deposited from chloro-fluoride melts. Only SiC was deposited from carbonate-silica melts under carbon dioxide atmosphere (that is, excessive pressure of CO2.

  20. Fluoride-assisted synthesis of bimodal microporous SSZ-13 zeolite.

    Zhu, Xiaochun; Kosinov, Nikolay; Hofmann, Jan P; Mezari, Brahim; Qian, Qingyun; Rohling, Roderigh; Weckhuysen, Bert M; Ruiz-Martínez, Javier; Hensen, Emiel J M

    2016-02-21

    The presence of small amount of fluoride in alkaline hydrothermal synthesis of SSZ-13 zeolite yields bimodal microporous particles with substantially improved performance in the methanol-to-olefins (MTO) reaction. Hydrocarbon uptake measurements and fluorescence microspectroscopy of spent catalysts demonstrate enhanced diffusion through micropores at the grain boundaries of nanocrystals running through the zeolite particles. Fluoride-assisted SSZ-13 synthesis is a cheap and scalable approach to optimize the performance of MTO zeolite catalysts. PMID:26810114

  1. Fluoride levels in commercial dentifrices and drinking Water in Algeria

    MERGHACHE, D.; BELLOUT, B.; MERGHACHE, S.; BOUCHERIT-ATMANI, Z.

    2011-01-01

    More and more scientific evidence show that fluorides have a cariostatic action to the plaque-saliva-tooth interface during cariogenous dissolution. Fluorides slow down demineralization and enhance remineralization. Their action is optimal, in the oral environment, when used at low concentrations on a continuous basis. The use of the fluorinated toothpastes during brushing of the teeth is a simple, rational method of daily topics application of fluorine, largely used in the context of prevent...

  2. Fluoride Concentration in Drinking Water Resources; North of Iran

    Amouei A.I. PhD,

    2016-03-01

    Full Text Available Aims Fluoride is one of the anions present in soil and water, and determining its level in drinking water is vital for preventing dental and bone diseases in societies. This research aimed to determine fluoride concentrations in drinking water sources of rural and urban areas of Babol City, Iran. Instrument & Methods This descriptive cross-sectional study was conducted in Babol City, Iran, in 2014. 384 water samples were taken from 43 wells and 3 springs in the rural areas, and from 20 wells, 3 water reservoirs, and the water distribution system in the urban areas. Fluoride concentrations of water samples were measured with a model DR2000 spectrophotometer using the standard SPADNS method. Data were entered to SPSS 16 software and were analyzed by ANOVA test. Findings The mean fluoride concentrations in the water samples of the deep wells were higher compared to those of the springs (p=0.01. The mean fluoride concentrations in the plains areas were higher compared to the mountainous regions (p=0.02. The mean fluoride concentrations in the wells of the urban areas, in the urban reservoirs, and in the urban water distribution system were 0.40±0.14, 0.39±0.15, and 0.40±0.15mg/l, respectively (p=0.07. Fluoride concentrations in water in urban areas during various seasons varied from 0.31 to 0.45mg/l (p=0.06. Conclusion Fluoride concentrations in all drinking water sources in urban and rural areas of Babol are less than the ranges recommended by WHO and Iranian national standards.

  3. EXPERIMENTAL STUDY AND NUMERICAL SIMULATION OF FLUORIDE IN SAND

    ZHANG Hong-mei; SU Bao-yu

    2006-01-01

    The transport and transformation of fluoride in sand were studied by using soil tank test under the condition of saturated water in this article. Based on the analysis of the laboratory experiments, the rules of fluorine transportation and transformation were simulated in sand by solving the advection-diffusion equation. Through comparison between computed results and observed data , it is shown that the established model and determined parameters could be used to simulate the fluoride transport in sand.

  4. Fluoride, aluminum, and phosphate kinetics in cryolite workers.

    Grandjean, P; Hørder, M; Thomassen, Y

    1990-01-01

    Exposure to cryolite (Na3AlF6) dust may result in skeletal fluorosis. Eight male workers at a cryolite concentrator participated in a 4-day study after 5 days of vacation. Dust exposures were 0.16 to 21.2 mg/m3. Urine was collected before work began and during two 4-hour periods. Preshift urine fluoride concentrations increased during the week. Fluoride concentrations in postshift urine and serum both correlated with the dust exposures. Serum fluoride concentrations decreased with a half-life of 3.3 to 6.9 hours after work. Fluoride clearance was 40.5 to 76.5 mL/min at urinary flow rates of 0.89 to 2.21 mL/min. Serum aluminum concentrations varied without relation to the exposure, but the urinary aluminum excretion correlated with the fluoride levels. Preshift serum-phosphate concentrations increased significantly during the week, possibly indicating changes in mineral metabolism. For monitoring of individual uptake of cryolite dust, serum fluoride measurements are most useful. PMID:2324845

  5. Fluoride and aluminum in teas and tea-based beverages

    Hayacibara Mitsue Fujimaki

    2004-01-01

    Full Text Available OBJECTIVE: To evaluate fluoride and aluminum concentration in herbal, black, ready-to-drink, and imported teas available in Brazil considering the risks fluoride and aluminum pose to oral and general health, respectively. METHODS: One-hundred and seventy-seven samples of herbal and black tea, 11 types of imported tea and 21 samples of ready-to-drink tea were divided into four groups: I-herbal tea; II-Brazilian black tea (Camellia sinensis; III-imported tea (Camellia sinensis; IV-ready-to-drink tea-based beverages. Fluoride and aluminum were analyzed using ion-selective electrode and atomic absorption, respectively. RESULTS: Fluoride and aluminum levels in herbal teas were very low, but high amounts were found in black and ready-to-drink teas. Aluminum found in all samples analyzed can be considered safe to general health. However, considering 0.07 mg F/kg/day as the upper limit of fluoride intake with regard to undesirable dental fluorosis, some teas exceed the daily intake limit for children. CONCLUSIONS: Brazilian and imported teas made from Camellia sinensis as well as some tea-based beverages are sources of significant amounts of fluoride, and their intake may increase the risk of developing dental fluorosis.

  6. Preparation of mixed rare earths modified chitosan for fluoride adsorption

    梁鹏; 张艺; 汪东风; 徐莹; 罗斓

    2013-01-01

    This paper described the fluoride removal from water using a new adsorbent namely mixed rare earths modified chitosan (CR). Mixed rare earths mainly contained La followed by Ce which was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). La(III)-modified chitosan (CL) was also prepared as control. For the batch technique, the effects of various parameters such as contact time, pH, adsorbent dose, initial fluoride concentration and co-ions on fluoride adsorption were studied. Fourier trans-form infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to characterize adsorbents. It was observed that the fluo-ride adsorption capacity of CR (3.72 mgF-/g) was higher than CL (3.16 mgF-/g) at 2 h. The presence of co-ions such as bicarbonate and carbonate greatly affected the fluoride adsorption from water. Characterization experiments indicated the successful chelation between mixed rare earths and chitosan. The possible fluoride adsorption mechanism of CR was explained by a chemical reaction.

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

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

    2016-05-01

    In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0-2mgl(-1). Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field. PMID:26874766

  8. Removal of fluoride from water using aluminium containing compounds

    M. Karthikeyan; K. P. Elango

    2009-01-01

    Batch adsorption studies were undertaken to assess the suitability of aluminium titanate (AT) and bismuth aluminate (BA) to remove fluoride ions from water.The effect of pH,dose of adsorbent,contact time,initial concentration,co-ions and temperature on fluoride removal efficiency were studied.The amounts of fluoride ions adsorbed,at 30℃ from 4 mg/L of fluoride ion solution,by AT and BA are 0.85 and 1.55 mg/g,respectively.The experimental data fitted well to the Freundlich and Langmuir isotherms.Thermodynamic parameters such as △H~0,△S~0 and △G~0 indicated that the removal of fluoride ions by AT is exothermic and non-spontaneous while that by BA is endothermic and spontaneous.Furrier transform infrared (FT-IR) analysis and X-ray diffraction (XRD) patterns of the adsorbent before and after adsorption indicated that fluoride ions are chemisorbed by these adsorbents.

  9. Water Fluoridation: A Critical Review of the Physiological Effects of Ingested Fluoride as a Public Health Intervention

    Stephen Peckham; Niyi Awofeso

    2014-01-01

    Fluorine is the world's 13th most abundant element and constitutes 0.08% of the Earth crust. It has the highest electronegativity of all elements. Fluoride is widely distributed in the environment, occurring in the air, soils, rocks, and water. Although fluoride is used industrially in a fluorine compound, the manufacture of ceramics, pesticides, aerosol propellants, refrigerants, glassware, and Teflon cookware, it is a generally unwanted byproduct of aluminium, fertilizer, and iron ore manuf...

  10. Using High Fluoride Concentration Products in Public Policy – A Rapid Review of Current Guidelines for High Fluoride Concentration products

    Douglas, GVA; Ramsdale, M; Vinall, K.; Csikar, J

    2016-01-01

    Despite improvements in caries levels since widespread introduction of fluoride toothpastes it remains a priority in many countries around the world. Higher caries risk individuals can be targeted with products with a high fluoride concentration to help reduce the amount and severity of disease. This paper compares guidance from around the world on the use of such products and gives examples of how guidance has been translated into activity in primary care dental practice. A rapid review of e...

  11. High Temperature Fluoride Salt Test Loop

    Aaron, Adam M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cunningham, Richard Burns [Univ. of Tennessee, Knoxville, TN (United States); Fugate, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holcomb, David Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kisner, Roger A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peretz, Fred J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yoder, Jr, Graydon L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

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

  12. Phytotoxicity of sodium fluoride and uptake of fluoride in willow trees.

    Clausen, Lauge Peter Westergaard; Karlson, Ulrich Gosewinkel; Trapp, Stefan

    2015-01-01

    The willow tree (Salix viminalis) toxicity test and a cress seed germination test (Lepidium sativum) were used to determine uptake of F and phytotoxicity of NaF. Concentrations in hydroponic solutions were 0-1000 mg F/L and 0-400 mg F/L in the preliminary and definitive test. A third test was done with soils collected from a fluoride-contaminated site at Fredericia, Denmark. The EC10, EC20 and EC50-values for inhibition of transpiration were determined to 38.0, 59.6 and 128.7 mg F/L, respectively. The toxicity test with soil showed strong inhibition for the sample with the highest fluoride concentration (405 mg free F per kg soil, 75 mg F per L soil solution). The seed germination and root elongation test with cress gave EC10, EC20 and EC50-values of 61.4, 105.0 and 262.8 mg F/L, respectively. At low external concentrations, fluoride was taken up more slowly than water and at high external concentrations at the same velocity. This indicates that an efflux pump becomes overloaded at concentrations above 210 mg F/L. Uptake kinetics were simulated with a non-linear mathematical model, and the Michaelis-Menten parameters were determined to half-saturation constant KM near 2 g F/L and maximum enzymatic removal rate vmax at 9 g/(kg d). PMID:25409250

  13. Chemico-therapeutic approach to prevention of dental caries. [using stannous fluoride gel

    Shannon, I. L.

    1975-01-01

    The program of chemical preventive dentistry is based primarily upon the development of a procedure for stabilizing stannous fluoride in solution by forcing it into glycerin. New topical fluoride treatment concentrates, fluoride containing gels and prophylaxis pastes, as well as a completely stable stannous fluoride dentifrice are made possible by the development of a rather complicated heat application method to force stannous fluoride into solution in glycerin. That the stannous fluoride is clinically effective in such a preparation is demonstrated briefly on orthodontic patients.

  14. The effect of different fluoride application methods on the remineralization of initial carious lesions

    Byeon, Seon Mi; Lee, Min Ho; Bae, Tae Sung

    2016-01-01

    Objectives The purpose of this study was to assess the effect of single and combined applications of fluoride on the amount of fluoride release, and the remineralization and physical properties of enamel. Materials and Methods Each of four fluoride varnish and gel products (Fluor Protector, FP, Ivoclar Vivadent; Tooth Mousse Plus, TM, GC; 60 Second Gel, A, Germiphene; CavityShield, CS, 3M ESPE) and two fluoride solutions (2% sodium fluoride, N; 8% tin(ii) fluoride, S) were applied on bovine t...

  15. Characterization of cerium fluoride nanocomposite scintillators

    Stange, Sy [Los Alamos National Laboratory; Esch, Ernst I [Los Alamos National Laboratory; Brown, Leif O [Los Alamos National Laboratory; Couture, Aaron J [Los Alamos National Laboratory; Mckigney, Edward A [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Gilbertson, Robert D [Los Alamos National Laboratory; Mccleskey, T Mark [Los Alamos National Laboratory; Reifarth, Rene [Los Alamos National Laboratory

    2009-01-01

    Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF{sub 3}) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

  16. Magnetic separation of uranium from magnesium fluoride

    The attraction or repulsion of particles by a magnetic gradient, based on the respective susceptibilities, provides the basis for physical separation of particles that are comprised predominantly of uranium from those that are predominantly magnesium fluoride (MgF2). To determine the effectiveness of this approach, a bench-scale magnetic separator from the S.G. Frantz Co., Inc. was used. In the Frantz Model L-1, particles are fed through a funnel onto a vibration tray and through a magnetic field. The specific design of the Frantz magnet causes the magnetic field strength to vary along the width of the magnet, setting up a gradient. The tray in the magnetic field is split at a point about half way down its length so that the separated material does not recombine. A schematic is presented of Frantz Model L-1 CN - the same magnet configured for high gradient magnetic separation of liquid-suspended particles. Here different pole pieces create a uniform magnetic field, and stainless steel wood in the canister between the pole pieces creates the high gradient. 1 ref., 6 figs., 2 tabs

  17. Characterization of cerium fluoride nanocomposite scintillators

    Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF3) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

  18. Thermodynamic data for treatment of fluoride

    To obtain uranium from Al2O3 with uranium by the electrolytic deduction method, the equilibrium potential of Ni(0)/Ni(2) in NaF-AlF3-Al2O3-NiF2 and its dependence on the concentration of Al2O3 were determined. On the coexistence system of Al2O3 and NiF2 in the molten salt, NiF2 was oxidized to NiO by the oxygen ion from Al2O3. Dependence of the equilibrium potential of Ni(0)/Ni(2) in NaF-AlF3-NiF2 on temperature was measured and the potential data were consistent with the Nernst equation, which showed the large effect of Al2O3 on oxidation of metallic fluoride in molten salt. These results proved that the stripping treatment of uranium in the coexistence system of Al2O3 by the electrolytic deduction method was difficult, because the effect of oxygen ion of Al2O3 was larger than the level of oxidation- reduction potential. (S.Y.)

  19. Magnetic separation of uranium from magnesium fluoride

    Hoegler, J.M.

    1987-01-01

    The attraction or repulsion of particles by a magnetic gradient, based on the respective susceptibilities, provides the basis for physical separation of particles that are comprised predominantly of uranium from those that are predominantly magnesium fluoride (MgF/sub 2/). To determine the effectiveness of this approach, a bench-scale magnetic separator from the S.G. Frantz Co., Inc. was used. In the Frantz Model L-1, particles are fed through a funnel onto a vibration tray and through a magnetic field. The specific design of the Frantz magnet causes the magnetic field strength to vary along the width of the magnet, setting up a gradient. The tray in the magnetic field is split at a point about half way down its length so that the separated material does not recombine. A schematic is presented of Frantz Model L-1 CN - the same magnet configured for high gradient magnetic separation of liquid-suspended particles. Here different pole pieces create a uniform magnetic field, and stainless steel wood in the canister between the pole pieces creates the high gradient. 1 ref., 6 figs., 2 tabs.

  20. Investigation of solubility of cesium, strontium, barium, rare-earth, uranium and americium fluorides in acid nitrosyl fluoride (NOFx3HF)

    Solubility of Am and other elements, which are fission products, in acid nitrosylfluoride has been studied. Cesium fluoride has maximum solubility; uranium tetrafluoride is also noticeably soluble; americium trifluoride is practically insoluble; fluorides of rare earth elements are slightly soluble in NOFx3HF. Analysis of the solid phase obtained after treating the mixture of the above fluorides with acid nitrosylfluoride has shown that cesium fluoride reacts with NOFx3HF with the formation of an acid salt (CsFxHF), whereas fluorides of alkaline and rare earth elements remain unchanged. The behaviour of a mixture of cesium, barium, and lanthanum fluorides in the process of three-multiple treating with acid nitrosylfluoride has been studied. It is shown that more than 98% of cesium fluoride and 5% of barium fluoride pass into the mother liquor while lanthanum fluoride remains completely in the solid phase. The data on americium fluoride solubility in acid nitrosylfluoride have indicated that it behaves in the same way as fluorides of rare earth elements; it is practically insoluble in HOFx3HF

  1. Profile of Fluoride Release from a Nanohybrid Composite Resin

    Raquel Assed Bezerra Silva

    2015-02-01

    Full Text Available The aim of this study was to evaluate in vitro the amount and profile of fluoride release from a fluoride-containing nanohybrid composite resin (Tetric® N-Ceram by direct potentiometry. Thirty specimens (5 mm diameter x 3 mm high; n=10/material were made of Tetric® N-Ceram, Vitremer® resin-modified glass ionomer cement (RMGIC (positive control or Filtek® Z350 nanofill composite resin (negative control. The specimens were stored individually in plastic tubes containing 1 mL of artificial saliva at 37°C, which was daily renewed during 15 days. At each renewal of saliva, the amount of fluoride ions released in the solution was measured using a fluoride ion-selective electrode with ion analyzer, and the values obtained in mV were converted to ppm (µg/mL. Data were analyzed statistically by ANOVA and Tukey’s post-hoc test at a significance level of 5%. The results showed that the resins Tetric® N-Ceram and Filtek® Z350 did not release significant amounts of fluoride during the whole period of evaluation (p>0.05. Only Vitremer® released significant amounts of fluoride ions during the 15 days of the experiment, with greater release in first 2 days (p0.05. In conclusion, the nanohybrid composite resin Tetric® N-Ceram did not present in vitro fluoride-releasing capacity throughout the 15 days of study.

  2. Stabilization of fluoroindate glasses by magnesium fluoride and other heavy metal fluorides

    B. J. Costa

    1998-06-01

    Full Text Available Their extended transparency in the IR makes them attractive for use as optical fibers for CO laser power delivery and optical amplification. This paper firstly describes the spectacular stabilizing effect of MgF2 on the binary system InF3-BaF2. The investigation of the InF3-BaF2-MgF2 system led to samples up to 5mm in thickness. Further optimization of this system was achieved by incorporation of limited amounts of other fluorides and resulted in increased resistence to devitrification. The second approach of this work was concerned to the investigation of the pseudo-ternary system InF3-GdF3-GaF3 at constant concentrations of ZnF2-SrF2-BaF2-NaF. Several compositions were studied in this system. The samples presented a better thermal stability when compared to other families of fluoride glasses. Therefore, these glasses seem to be very promising for the fabrication of special optical fibers. Thermal data are reported.

  3. Electrochemical properties of uranium, cerium, and zirconium in the lithium fluoride - barium fluoride eutectic

    The aim of this work has been to determine the possibility of carrying out an electrochemical analysis of the ions U4+, Ce3+, Zr4+ in a fluoride melt, and to obtain some of the electrochemical properties of these ions. It was first of all necessary to develop a method for purifying the LiF-BaF2 eutectic so as to have melts of sufficient purity for carrying out an electrochemical study using linear chrono-amperometry and chrono-potentiometry. The polarization curves recorded in solutions for the ions U4+, Ce3+, Zr4+ show that the systems U4+/U3+, Ce3+/Ce4+ and Zr4+/Zr are rapid. After it had been checked that mass transport on the electrode is controlled by diffusion, the diffusion coefficients for the ions Ce3+, U4+ and Zr4+ were determined. The oxidizing nature of the ion Ce4+ makes it possible to dissolve ceric oxide in the molten fluoride. Furthermore the existence of two zirconium oxyfluorides has been demonstrated, they appear after dissolution of the zirconia in a solution of zirconium tetrafluoride. From a practical point of view these results are of interest for the preparation of metals by electrolytic reduction of their oxides. (author)

  4. In vivo and in vitro studies of a cetylamine fluoride mouthrinse: evaluation of a device used for in vitro experiments

    CARVALHO Sílvia Magaly Sasso

    1999-01-01

    Full Text Available A mouthrinse containing cetylamine fluoride (230 ppm in fluoride was prepared for in vitro studies of fluoride clearance and adsorption by enamel and/or hydroxyapatite using a device that simulates the oral cavity. In vivo studies of fluoride clearance from this mouthrinse were conducted and compared with other fluoride sources. The amount of fluoride adsorbed to tooth blocks or powdered hydroxyapatite, both treated with this cetylamine fluoride mouthrinse once or twice a day, was determined. The results of these studies showed that it is possible to prepare a mouthrinse with cetylamine fluoride for alternative use by patients for the prevention and therapy of dental caries.

  5. An Overview of Liquid Fluoride Salt Heat Transport Systems

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

    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

  6. Recommendations for fluoride limits in drinking water based on estimated daily fluoride intake in the Upper East Region, Ghana.

    Craig, Laura; Lutz, Alexandra; Berry, Kate A; Yang, Wei

    2015-11-01

    Both dental and skeletal fluorosis caused by high fluoride intake are serious public health concerns around the world. Fluorosis is particularly pronounced in developing countries where elevated concentrations of naturally occurring fluoride are present in the drinking water, which is the primary route of exposure. The World Health Organization recommended limit of fluoride in drinking water is 1.5 mg F(-) L(-1), which is also the upper limit for fluoride in drinking water for several other countries such as Canada, China, India, Australia, and the European Union. In the United States the enforceable limit is much higher at 4 mg F(-) L(-1), which is intended to prevent severe skeletal fluorosis but does not protect against dental fluorosis. Many countries, including the United States, also have notably lower unenforced recommended limits to protect against dental fluorosis. One consideration in determining the optimum fluoride concentration in drinking water is daily water intake, which can be high in hot climates such as in northern Ghana. The results of this study show that average water intake is about two times higher in Ghana than in more temperate climates and, as a result, the fluoride intake is higher. The results also indicate that to protect the Ghanaian population against dental fluorosis, the maximum concentration of fluoride in drinking water for children under 6-8 years should be 0.6 mg F(-) L(-1) (and lower in the first two years of life), and the limit for older children and adults should be 1.0 mg F(-) L(-1). However, when considering that water treatment is not cost-free, the most widely recommended limit of 1.5 mg F(-) L(-1) - which is currently the limit in Ghana--may be appropriate for older children and adults since they are not vulnerable to dental fluorosis once the tooth enamel is formed. PMID:26058000

  7. Fluorides in groundwater and its impact on health.

    Shailaja, K; Johnson, Mary Esther Cynthia

    2007-04-01

    Fluoride is a naturally occurring toxic mineral present in drinking water and causes yellowing of teeth, tooth problems etc. Fluorspar, Cryolite and Fluorapatite are the naturally occurring minerals, from which fluoride finds its path to groundwater through infiltration. In the present study two groundwater samples, Station I and Station II at Hyderabad megacity, the capital of Andhra Pradesh were investigated for one year from January 2001 to December 2001. The average fluoride values were 1.37 mg/l at Station I and 0.91 mg/l at Station II. The permissible limit given by BIS (1983) 0.6-1.2 mg/l and WHO (1984) 1.5 mg/l for fluoride in drinking water. The groundwaters at Station I exceeded the limit while at Station II it was within the limits. The study indicated that fluoride content of 0.5 mg/l is sufficient to cause yellowing of teeth and dental problems. PMID:17915775

  8. On the solubility of rare earth fluorides in mineral acids

    The results of the investigation of rare earth fluoride solubility in a wide range of nitric acid concentrations are presented. The fluoride solubility monotonously increases with the nitric acid concentration and upon attaining a certain maximum again decreases. The maximum solubility region for all fluorides studied is located in definite concentration limits of the acid. The YF3 these values correspond to 2.0 g/l, for NdF3-2.32, SmF3 -2.25, PrF3 - 0.72, EuF3 - 1.66 g/l within the limits of 3.1-6.0 mol/l of nitric acid. Such course of the solubility curve is bound up with the change of hydrogen ion concentration in the solution. Solubility product values have been obtained for rare earth fluorides in the HNO3 concentration range from 0.42 to 1.3 mol/l. It is shown that rare earth fluorides have low solubility product values in nitric acid and their solubility product values depend on hydrogen ion concentration

  9. Improved fluoride volatility reprocessing for MOX fuel cycle

    Takahashi, M.; Fukasawa, T.; Sawa, T.; Yamashita, J.; Kamoshida, M.; Sasahira, A.; Kawamura, F. [Nuclear Systems Div., Hitachi, Ibaraki (Japan)

    2000-07-01

    Several countries had stopped developing fluoride volatility reprocessing method in the 1970's due to difficulties in recovering pure Pu. Although, nuclear societies recently favor dirty Pu (MOX). which has high proliferation resistance and needs remote fuel fabrication technologies. This situation reminded the authors to re-evaluate the fluoride volatility process. Preliminary investigation clarified that conventional fluoride volatility process could be simplified to recover dirty MOX and pure U from spent LWR fuels. Pure U is suitable to transfer it to re-enrichment (LWR cycle again), to storage certain period for future FBRs, and to dispose with relatively simple barrier. The improved process also enables to prepare directly the dirty MOX particles which are suitable for remote fuel fabrication (vibration packing). This paper describes the system of improved fluoride volatility reprocessing, and compatibility of each elemental process such as thermal decladding, two stage fluorination of U and U+Pu, U purification, direct conversion. of mixed fluoride into oxide particles and vibration packing fuel fabrication. (authors)

  10. A Review on Adsorption of Fluoride from Aqueous Solution

    Mirna Habuda-Stanić

    2014-09-01

    Full Text Available Fluoride is one of the anionic contaminants which is found in excess in surface or groundwater because of geochemical reactions or anthropogenic activities such as the disposal of industrial wastewaters. Among various methods used for defluoridation of water such as coagulation, precipitation, membrane processes, electrolytic treatment, ion-exchange, the adsorption process is widely used. It offers satisfactory results and seems to be a more attractive method for the removal of fluoride in terms of cost, simplicity of design and operation. Various conventional and non-conventional adsorbents have been assessed for the removal of fluoride from water. In this review, a list of various adsorbents (oxides and hydroxides, biosorbents, geomaterials, carbonaceous materials and industrial products and by-products and its modifications from literature are surveyed and their adsorption capacities under various conditions are compared. The effect of other impurities on fluoride removal has also been discussed. This survey showed that various adsorbents, especially binary and trimetal oxides and hydroxides, have good potential for the fluoride removal from aquatic environments.

  11. Fluoride and aluminum release from restorative materials using ion chromatography

    Zeynep Okte

    2012-02-01

    Full Text Available OBJECTIVE: The aim of this study was to determine the amounts of fluoride and aluminum released from different restorative materials stored in artificial saliva and double-distilled water. Material and METHODS: Cylindrical specimens (10 x 1 mm were prepared from 4 different restorative materials (Kavitan Plus, Vitremer, Dyract Extra, and Surefil. For each material, 20 specimens were prepared, 10 of which were stored in 5 mL artificial saliva and 10 of which were stored in 5 mL of double-distilled water. Concentrations of fluoride and aluminum in the solutions were measured using ion chromatography. Measurements were taken daily for one week and then weekly for two additional weeks. Data were analyzed using two-way ANOVA and Duncan's multiple range tests (p<0.05. RESULTS: The highest amounts of both fluoride and aluminum were released by the resin-modified glass ionomer cement Vitremer in double-distilled water (p<0.05. All materials released significantly more fluoride in double-distilled water than in artificial saliva (p<0.05. In artificial saliva, none of the materials were observed to release aluminum. CONCLUSION: It was concluded that storage media and method of analysis should be taken into account when the fluoride and aluminum release from dental materials is assessed.

  12. Assessment and control of nitrates and fluorides in the groundwater of Pakistan

    About 500 samples were analyzed for nitrate. Higher concentration was found from the cities of southern Punjab. For the city of Bahawalpur, the value varied from 8.2-40.3 mg/l as N. For Bahalwalnagar, the value ranged from 10.1-41.2 mg /I as N. For Sadiqabad, maximum values were obtained from Basti Mian Sahib and area surrounding the National Highway. The value ranged from 14.9-44.9 mg/ I. Control techniques are discussed. Out of total number of samples analyzed for fluoride, 43.5 % had fluoride < 0.5 mg/l, which require fluoridation, 26.4 % were in the desirable range, whereas, 29.7% had fluoride in excess which need de fluoridation. Investigation on the de fluoridation indicated that flocculation with alum was effective, but the efficiency was alkalinity dependent. For fluoridation, addition of fluoride in the tooth paste and mouthwash has proved to be effective. (author)

  13. Corrosion Behavior of Titanium Grade 7 in Fluoride-Containing NaCl Brines

    Lian, T; Whalen, M T; Wong, L

    2004-10-25

    The effects of fluoride on the corrosion behavior of Titanium Grade 7 (0.12-0.25% Pd) have been investigated. Up to 0.1 mol/L fluoride was added to the NaCl brines at 95 C, and three pH values of 4, 8, and 11 were selected for studying pH dependence of fluoride effects. It was observed that fluoride significantly altered the anodic polarization behavior, at all three pH values of 4, 8, and 11. Under acidic condition fluoride caused active corrosion. The corrosion of Titanium grade 7 was increased by three orders of magnitude when a 0.1 mol/L fluoride was added to the NaCl brines at pH 4, and the Pd ennoblement effect was not observed in acidic fluoride-containing environments. The effects of fluoride were reduced significantly when pH was increased to 8 and above.

  14. Caries status in 16 year-olds with varying exposure to water fluoridation in Ireland.

    Mullen, J

    2012-12-01

    Most of the Republic of Ireland\\'s public water supplies have been fluoridated since the mid-1960s while Northern Ireland has never been fluoridated, apart from some small short-lived schemes in east Ulster.

  15. A NOVEL BIO-WASTE INCORPORATED ALGINATE SORBENT FOR DE-FLUORIDATION OF WATER

    Carmalin Sophia Ayyappan

    2015-09-01

    Full Text Available This study evaluates the feasibility of using tamarind (Tamarindus indica seed powder for de-fluoridation of fluoride contaminated water. Batch study confirmed that tamarind seeds in dry powder form could remove 87% of fluoride from water. This bio-sorbent can be used effectively in areas where fluoride concentrations are above the permissible limits of 1.5 mg·l-1 as per WHO Standard, 1984. Tamarind seed powder was incorporated in a matrix of sodium alginate and made into gel-beads. The beads were tested for de-fluoridation efficiency by conducting column studies. The effect of various factors, such as flow rate, retention time, and the number of runs on the efficacy of fluoride removal was also studied. The results revealed that flow rate did not seem to have much effect on the percentage fluoride removal but the fluoride concentration decreased drastically upon greater retention time and multiple runs.

  16. Tetrabutylammonium fluoride promoted regiospecific reactions of trimethylsilyl-o-carborane with aldehydes

    Trimethylsilyl-o-carborane serves as o-carborane carbanion upon fluoride ion promoted reaction with carbonyl compounds. Thus, in the presence of tetrabutylammonium fluoride, trimethylsilyl-o-carborane undergoes facile, unprecedented, carbodesilylation with aromatic and aliphatic aldehydes. (author)

  17. Analyse van fluoride en fosfaat in complexe milieumatrices met capillaire zone elektroforese

    Staden JJ van; Hoop MAGT van den; LAC

    1996-01-01

    Dit onderzoek bestudeert de toepasbaarheid van een eerder ontwikkelde methode voor de analyse van fluoride en fosfaat op meer complexe matrices zoals oppervlaktewater, loogextracten, grondwater en stemflowwater. De storende waterstofcarbonaat-piek bij de bepaling van fluoride in loogextracten ko

  18. The Karlsruhe 4π barium fluoride detector

    A new experimental approach has been implemented for accurate measurements of neutron capture cross sections in the energy range from 5 to 200 keV. The Karlsruhe 4π Barium Fluoride Detector consists of 42 crystals shaped as hexagonal and pentagonal truncated pyramids forming a spherical shell with 10 cm inner radius and 15 cm thickness. All crystals are supplied with reflector and photomultiplier, thus representing independent gamma-ray detectors. Each detector module covers the same solid angle with respect to a gamma-ray source located in the centre. The energy resolution of the 4π detector is 14% at 662 keV and 7% at 2.5 MeV gamma-ray energy, the overall time reslution is 500 ps and the peak efficiency 90% at 1 MeV. The detector allows to register capture cascades with 95% probability above a threshold energy of 2.5 MeV in the sum energy spectrum. Neutrons are produced via the 7Li(p,n)7Be reaction using the pulsed proton beam of a Van de Graaff accelerator. The neutron spectrum can be taylored according to the experimental requirements in an energy range from 5 to 200 keV by choosing appropriate proton energies. A collimated neutron beam is passing through the detector and hits the sample in the centre. The energy of captured neutrons is determined via time of flight, the primary flight path being 77 cm. The combination of short primary flight path, a 10 cm inner radius of the spherical BaF2 shell, and the low capture cross section of barium allows to discriminate background due to capture of sample scattered neutrons in the scintillator by time of flight, leaving part of the neutron energy range completely undisturbed. (orig./HSI)

  19. Fluoride content and dependence on other elements in some geotermal waters in Republic of Macedonia

    Sijakova-Ivanova, Tena; Ambarkova, Vesna; Topitsogloy, Vassiliki; Zajkova-Paneva, Vesna

    2010-01-01

    The paper presents the results obtained for the fluoride content in some geothermal waters in Republic of Macedonia. The results made it possible to determine the dependence between fluoride and other chemical elements in the geothermal water. Fluoride content was determined with jon-analyser (EA 920 ORION) and Ion selective electrode for detection of trace fluoride. For chemical analysis was used 10% TISAB Alumina. Samples were collected in plastic bottles and kept in dark place ...

  20. Effect of high fluoride concentration in drinking water on children’s intelligence

    Seraj B.; Shahrabi M; Falahzade M; Falahzade F; Akhondi N.

    2006-01-01

    Background and Aim: Human and animal studies linking fluoride with diminished intelligence have been published. Although adverse effects of high intake of fluoride on intelligence and mental acuity continue to be reported, they are still controversial. The aim of this research was to investigate the relationship between fluoride in drinking water and children's intelligence. Materials and Methods: In this cross sectional study, 41 children were selected from the high fluoride area with 2...

  1. Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics

    Xiaojing Chen; Xiaohui Chen; Brauer, Delia S.; Rory M. Wilson; Hill, Robert G.; Natalia Karpukhina

    2014-01-01

    The bioactivity of a series of fluoride-containing sodium-free calcium and strontium phosphosilicate glasses has been tested in vitro. Glasses with high fluoride content were partially crystallised to apatite and other fluoride-containing phases. The bioactivity study was carried out in Tris and SBF buffers, and apatite formation was monitored by XRD, FTIR and solid state NMR. Ion release in solutions has been measured using ICP-OES and fluoride-ion selective electrode. The results show that...

  2. Kinetic Analysis of 18F-Fluoride PET Images of Breast Cancer Bone Metastases

    Doot, Robert K; Muzi, Mark; Peterson, Lanell M.; Schubert, Erin K; Gralow, Julie R.; Specht, Jennifer M.; Mankoff, David A.

    2010-01-01

    The most common site of metastasis for breast cancer is bone. Quantitative 18F-fluoride PET can estimate the kinetics of fluoride incorporation into bone as a measure of fluoride transport, bone formation, and turnover. The purpose of this analysis was to evaluate the accuracy and precision of 18F-fluoride model parameter estimates for characterizing regional kinetics in metastases and normal bone in breast cancer patients.

  3. Fluorescent naphthalene-based benzene tripod for selective recognition of fluoride in physiological condition

    Barun kumar Datta; Chirantan Kar; Gopal Das

    2015-02-01

    Aluminium complex of a naphthalene-based benzene tripod ligand system has been reported for the selective recognition of fluoride in aqueous medium in physiological condition. The ligand can selectively recognize Al3+ through enhancement in the fluorescence intensity and this in situ formed aluminium complex recognizes fluoride through quenching of fluorescence. The receptor system detects fluoride in nanomolar range. The sensing property was extended for practical utility to sense fluoride in tap water, pond water and river water.

  4. Synthesis and Characterization of New Antibacterial Fluoride-Releasing Monomer and Dental Composite

    Wang, Yapin; Samoei, George K.; LALLIER, THOMAS E.; Xu, Xiaoming

    2012-01-01

    A new dimethacrylate chelating monomer containing a BisGMA-like backbone structure and a bis(carboxymethyl)-L-lysine chelating group and its ternary zirconium-fluoride complex (antibacterial fluoride-releasing monomer) have been synthesized. The monomer structures were confirmed by 1H-NMR, 13C-NMR, and ES-MS analysis. Several experimental fluoride-releasing dental composites containing different quantities of the new antibacterial fluoride-releasing monomer were formulated and tested for fluo...

  5. Effects of fluoride in drinking water on health of deciduous teeth

    Blagojević Duška; Stojšin Ivana

    2004-01-01

    INTRODUCTION High incidence of decayed deciduous teeth, as well as lack of adequate therapy, makes tooth decay prevention very important. One of the simplest ways to reduce tooth decay is fluoridation of drinking water. The optimal concentration of fluoride in drinking water is 1 ppm/l, and many waters naturally contain this quantity. Waters in Vojvodina are mainly poor in fluoride, except in a few regions. It has long been postulated that fluoride has a prophyilactic effect during intrauteri...

  6. Absorption, distribution and excretion of inhaled hydrogen fluoride in the rat

    Morris, J.B.

    1979-01-01

    Rats were subjected to whole body HF exposure for 6 hrs or to nose-only HF exposure for 1 hr. Total and/or ionic fluoride concentrations in selected tissues were determined at various times following exposure. In rats sacrificed 6 hrs after whole body exposure, dose-dependent increases in lung, plasma, and kidney total and ionic fluoride concentration occurred. Rats excreted more fluoride in the urine after whole body exposure than could be explained by the amount of HF inhaled. Considerable evidence suggests that airborne HF deposits on fur and is then ingested due to preening activity. Urinary fluoride excretion was increased by nose-only exposure. The urinary fluoride excretion accounted for approximately twice the fluoride estimated to be inhaled during exposure. Tissue fluoride concentrations were elevated immediately after nose-only exposure. Fluoride concentrations in lung and kidney returned to control levels within 12 hrs. Plasma fluoride concentration was slightly elevated 24 hrs after the start of the 1 hr exposure but was at control levels at 96 hrs. Immediately following nose-only exposure, lung ionic fluoride concentrations were less than plasma ionic fluoride concentrations suggesting that the fluoride in the lung had reached that site via plasma transport rather than by inhalation. A dose-dependent increase in plasma ionic fluoride concentration occurred after upper respiratory tract HF exposure providing strong evidence that fluoride is absorbed systemically from that site. The plasma ionic fluoride concentration after upper respiratory tract exposure was of sufficient magnitude to account for the plasma fluoride concentrations observed in intact nose-only exposed rats. (ERB)

  7. Effect of sodium fluoride in maternal and offspring rats and its amelioration

    Sneha Panchal

    2014-03-01

    Full Text Available High fluoride content is known to cause dental and skeletal abnormalities. In addition, present review indicates that sodium fluoride consumption caused increased number of r=esorptions and dead foetuses. Various skeletal anomalies such as wavy ribs, presence of 14th ribs, lacking 6th sternebrae and incompete ossification of skull occur. All these changes could be due to oxidative stress caused by fluoride consumption. Fluoride-induced changes could be successfully ameliorated by cotreatment with vitamins and calcium.

  8. The Effect of Acute Fluoride Poisoning on Nitric Oxide and Methemoglobin Formation in the Guinea pig

    ŞİRELİ, Meltem

    2004-01-01

    To study the effect of acute fluoride poisoning on nitric oxide and methemoglobin formation, 250 mg/kg bw sodium fluoride was applied alone and verapamil was applied together with fluoride. Blood nitric oxide (Griess reaction) and calcium levels; hemoglobin, methemoglobin and hematocrit values; and erythrocyte counts were determined and compared with those of the controls. After the fluoride application it was found that there was a relative relationship between the increase in nitric oxide a...

  9. Reducing Exposure to High Fluoride Drinking Water in Estonia—A Countrywide Study

    Ene Indermitte; Astrid Saava; Enn Karro

    2014-01-01

    Fluoride is a naturally occurring contaminant in groundwater in Estonia. There are several regions in Estonia with fluoride contents in public water supplies as high as 7 mg/L. Long-term exposure to high-fluoride drinking water may have several adverse health effects, primarily dental fluorosis. The opportunities for exposure reduction rely highly on water treatment technologies. Since 2004 public water suppliers in Estonia have made efforts to diminish fluoride content in drinking water sys...

  10. Batch and Column Experiments on Fluoride Removal from Waters Using Modified Zeolite

    2000-01-01

    High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride-removing adsorbent. Batch and column experiments on fluoride removal using modified zeolites treated with hydrochloric acid,sodium hydroxide, sodium chloride and ferric chloride, respectively show that 0. 1 mol/L HCImodified zeolite can be used as an adsorbent for fluoride, with an adsorption capacity of 173. 16mg/kg.

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

    Yoder Jr, Graydon L [ORNL; Heatherly, Dennis Wayne [ORNL; Williams, David F [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; Caja, Joseph [Electrochemical Systems, Inc.; Caja, Mario [ORNL; Jordan, John [Texas A& M University, Kingsville; Salinas, Roberto [Texas A& M University, Kingsville

    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.

  12. Development of multifunctional chitosan beads for fluoride removal

    Chitosan beads (CB) which have negligible defluoridation capacity (DC) have been chemically modified by introducing multifunctional groups, viz., NH3+ and COOH groups by means of protonation and carboxylation in order to utilize both amine and hydroxyl groups for fluoride removal. The protonated cum carboxylated chitosan beads (PCCB) showed a maximum DC of 1800 mg F-/kg whereas raw chitosan beads displayed only 52 mg F-/kg. Sorption process was found to be independent of pH and slightly influenced in the presence of other common anions. The fluoride sorption on modified forms was reasonably explained by Freundlich and Langmuir isotherms. The sorbents were characterised by FTIR and SEM with EDAX analysis. The sorption process follows pseudo-second-order and intraparticle diffusion kinetic models. The suitability of PCCB has been tested with field sample collected from a nearby fluoride endemic area.

  13. Caries prevention with fluoride toothpaste in children: an update

    Twetman, S

    2009-01-01

    AIM: The aim was to examine recent literature and review the caries-preventive effect of fluoride toothpaste in children. METHODS: Based on three comprehensive systematic reviews published in 2003, a broad search of the PubMed and Cochrane library databases was conducted for papers published 2002...... significant caries-preventive effect in children compared with placebo (prevented fraction 24%). The effect was boosted by supervised tooth brushing, increased brushing frequency to twice daily, and use of a toothpaste concentration of 1,500 ppm fluoride. There were few studies of high quality reporting...... findings from the primary dentition. There were no studies available, and therefore insufficient evidence, on when to commence brushing with fluoride toothpaste as well as on the post-brushing behaviour. The use of "adult" toothpaste in very young children seemed to increase the risk for mild dental...

  14. Effects of chlorhexidine and fluoride on irradiated enamel and dentin.

    Soares, C J; Neiva, N A; Soares, P B F; Dechichi, P; Novais, V R; Naves, L Z; Marques, M R

    2011-05-01

    The effectiveness of mouthwash protocols in preventing gamma irradiation therapy damage to the ultimate tensile strength (UTS) of enamel and dentin is unknown. It was hypothesized that the use of chlorhexidine and fluoride mouthwash would maintain the UTS of dental structures. One hundred and twenty teeth were divided into 2 groups: irradiated (subjected to 60 Gy of gamma irradiation in daily increments of 2 Gy) and non-irradiated. They were then subdivided into 2 mouthwash protocols used 3 times per day: 0.12% chlorhexidine, 0.05% sodium fluoride, and control group (n = 10). The specimens were evaluated by microtensile testing. The results of the Tukey test (p Mouthwash with 0.12% chlorhexidine partially prevented the damage to the mechanical properties of the irradiated crown dentin, whereas the 0.05% sodium-fluoride-irradiated enamel showed UTS similar to that of non-irradiated enamel. PMID:21335538

  15. Sulfonyl fluoride inhibitors of fatty acid amide hydrolase.

    Alapafuja, Shakiru O; Nikas, Spyros P; Bharathan, Indu T; Shukla, Vidyanand G; Nasr, Mahmoud L; Bowman, Anna L; Zvonok, Nikolai; Li, Jing; Shi, Xiaomeng; Engen, John R; Makriyannis, Alexandros

    2012-11-26

    Sulfonyl fluorides are known to inhibit esterases. Early work from our laboratory has identified hexadecyl sulfonylfluoride (AM374) as a potent in vitro and in vivo inhibitor of fatty acid amide hydrolase (FAAH). We now report on later generation sulfonyl fluoride analogs that exhibit potent and selective inhibition of FAAH. Using recombinant rat and human FAAH, we show that 5-(4-hydroxyphenyl)pentanesulfonyl fluoride (AM3506) has similar inhibitory activity for both the rat and the human enzyme, while rapid dilution assays and mass spectrometry analysis suggest that the compound is a covalent modifier for FAAH and inhibits its action in an irreversible manner. Our SAR results are highlighted by molecular docking of key analogs. PMID:23083016

  16. Buffer modification in determination of fluoride using selective ion electrode

    Determination of Fluoride in the Lanonorm 1 as Standard Reference material for urine OOSA 52/53 was done by Fluoride Ion selective Electrode Preparation of TISB (Total Ionic Strength Adjustor Buffer) was modified with Sodium and Potassium Chloride Salt at the pH 5,3. Standard Solution had been made 2 ppb until 9.10 exp. 4 ppb F from NaF and KF salt. The pH of TISB was made 5.3 ISE Fluoride and Double junction Reference 3,5 M KCl in outer compartment had been Installed within Metrohm 654 Potentiometer for investigating potential. Best result sample with error 3,6 % was found by TISB Natrium which use KF as calibration standard solution. (author)

  17. Antimicrobial and fluoride release capacity of orthodontic bonding materials

    Erika Machado Caldeira

    2013-07-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the antimicrobial and fluoride releasing capacity of 3 bonding materials. MATERIAL AND METHODS: Thirty nine specimens with standardized surface smoothness and dimensions were prepared. The antimicrobial capacity of the materials against S. mutans, L. casei and C. albicans was evaluated by determining the percentage of growth inhibition of these microorganisms in an inoculated medium, obtained by optical density readouts on a spectrophotometer. The potential to interfere in microbial growth on the surface of the studied materials was observed by means of scanning electron microscopy (SEM. The fluoride release capacity in ultrapure water for 14 days was analyzed by means of ion chromatography. RESULTS: The PLUS group presented the highest percentage of microbial inhibition and the most contamination-free surface. The FUJI group presented the best fluoride release capacity. CONCLUSIONS: The TransbondTM Plus Color Change was the one that presented the best general behavior considering the evaluated aspects.

  18. Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation

    Waugh, Declan T.; Potter, William; Limeback, Hardy; Godfrey, Michael

    2016-01-01

    The Republic of Ireland (RoI) is the only European Country with a mandatory national legislation requiring artificial fluoridation of drinking water and has the highest per capita consumption of black tea in the world. Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, fifty four brands of the commercially available black tea bag products were purchased and the fluoride level in tea infusions tested by an ion-selective electrode method. The fluoride content in all brands tested ranged from 1.6 to 6.1 mg/L, with a mean value of 3.3 mg/L. According to our risk assessment it is evident that the general population in the RoI is at a high risk of chronic fluoride exposure and associated adverse health effects based on established reference values. We conclude that the culture of habitual tea drinking in the RoI indicates that the total cumulative dietary fluoride intake in the general population could readily exceed the levels known to cause chronic fluoride intoxication. Evidence suggests that excessive fluoride intake may be contributing to a wide range of adverse health effects. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population. PMID:26927146

  19. Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation.

    Waugh, Declan T; Potter, William; Limeback, Hardy; Godfrey, Michael

    2016-03-01

    The Republic of Ireland (RoI) is the only European Country with a mandatory national legislation requiring artificial fluoridation of drinking water and has the highest per capita consumption of black tea in the world. Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, fifty four brands of the commercially available black tea bag products were purchased and the fluoride level in tea infusions tested by an ion-selective electrode method. The fluoride content in all brands tested ranged from 1.6 to 6.1 mg/L, with a mean value of 3.3 mg/L. According to our risk assessment it is evident that the general population in the RoI is at a high risk of chronic fluoride exposure and associated adverse health effects based on established reference values. We conclude that the culture of habitual tea drinking in the RoI indicates that the total cumulative dietary fluoride intake in the general population could readily exceed the levels known to cause chronic fluoride intoxication. Evidence suggests that excessive fluoride intake may be contributing to a wide range of adverse health effects. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population. PMID:26927146

  20. An In Vitro Study of the Effect of Fluoridated Milk on Oral Bacterial Biofilms

    Pratten, J.; Bedi, R.; Wilson, M

    2000-01-01

    Microcosmic dental plaques were grown in artificial saliva and supplemented with either milk or fluoridated milk. The presence of fluoride in the milk increased the pH of the biofilms and reduced the proportions of streptococci, demonstrating that in this model, fluoridation of milk produces biofilms with reduced cariogenic potential.

  1. 40 CFR 142.61 - Variances from the maximum contaminant level for fluoride.

    2010-07-01

    ... level for fluoride. 142.61 Section 142.61 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... from the maximum contaminant level for fluoride. (a) The Administrator, pursuant to section 1415(a)(1... means generally available for achieving compliance with the Maximum Contaminant Level for fluoride....

  2. 76 FR 19001 - Sulfuryl Fluoride; Addendum to Proposed Order Granting Objections to Tolerances and Denying...

    2011-04-06

    ... the Proposed Order On January 19, 2011 (76 FR 3422, Jan. 19, 2011), EPA issued a proposed order... AGENCY 40 CFR Part 180 Sulfuryl Fluoride; Addendum to Proposed Order Granting Objections to Tolerances... supplementing its proposed order published January 19, 2011, regarding sulfuryl fluoride and fluoride...

  3. 40 CFR 141.208 - Special notice for exceedance of the SMCL for fluoride.

    2010-07-01

    ... SMCL for fluoride. 141.208 Section 141.208 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Drinking Water Violations § 141.208 Special notice for exceedance of the SMCL for fluoride. (a) When is the special notice to be given? Community water systems that exceed the fluoride secondary maximum...

  4. Spectrophotometric study of the reaction of zirconium with chrome Azurol S and fluoride

    A relatively simple and convenient procedure for the determination of small amounts of fluoride has been established. It is based on the decrease in absorbance when fluoride is added to a solution of the zirconium-Chrome Azurol S complex. Microgram amounts of fluoride can be determined with an error of better than about 2%. Some practical applications are presented. (author)

  5. Antireflection coatings for Si-base photoelectrical devices made of lanthanum, samarium and dysprosium fluorides

    Spectral dependences of light transmission through rare-element fluorides and the antireflection effect of the surface of silicon photoelectric converters with usage of the fluorides are investigated. It is established that fluoride films of lanthanum, samarium and dysprosium have a high transparency in the spectral reflection coefficient for a silicon surface up to 3.3-4.0%

  6. Contemporary perspective on the use of fluoride products in caries prevention

    J.M. ten Cate

    2013-01-01

    Dental caries has declined in the 40 years since fluoridated toothpastes were introduced. Much has been learned about why fluoride is so effective and how this knowledge can be used to optimise programmes for caries prevention. Fluoride works through enhancing the remineralisation of early stages of

  7. 76 FR 2383 - Proposed HHS Recommendation for Fluoride Concentration in Drinking Water for Prevention of Dental...

    2011-01-13

    ... HUMAN SERVICES Proposed HHS Recommendation for Fluoride Concentration in Drinking Water for Prevention... to recommendations for fluoride concentrations in drinking water. The U.S. Public Health Service... ranged from 0.7-1.2 mg/L. HHS proposes that community water systems adjust the amount of fluoride to...

  8. Fluoride Consumption and Its Impact on Oral Health

    Luis Fernando Jacinto-Alemán

    2011-01-01

    Full Text Available 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.

  9. Experimental testing of fluorides in the treatment of periodontal diseases

    Having received a periodontally pathogenic diet over a period of 2 months, Syrian hamsters exhibited a normalized incorporation of 45Ca and 32P into the mineral fraction and an enhancement of the distrubed incorporation of 32P and 14C-labelled lysine into the protein fraction of jaw and femoral bone tissues after enteral administration of fluoride. Electrophoretic treatment with Ca normalized the disturbed 32P and 14C-lysine incorporation into the protein fraction. The combined use of 2 therapeutic factors proved to be most favorable for both the mineral and the protein metabolism and reduced the negative effects caused by sole application of fluoride

  10. Investigation of In Vitro Effects of Fluoride on Bovine Sperm

    TANYILDIZI, Sadettin

    2002-01-01

    The in vitro effects of various concentrations of sodium fluoride on the percentages of motile spermatozoa and abnormal spermatozoa with the hyaluronidase activities of semen were investigated. Holstein bulls (n=20), aged between 4 and 5 years, were used in this study. The semen samples obtained from all animals were divided into five parts and one of them was used as the control sample. Sodium fluoride solutions were prepared at concentrations of 30, 60, 120 and 240mM and then these solutio...

  11. Thermoluminescent lithium fluorides dosemeters in personnel monitoring in the GDR

    Described are thermoluminescent (TL) dosemeters of lithium fluoride used in centralized personnel monitoring in the GDR. Results of large-scale experiment are presented to compare the accuracy of readings of lithium fluoride or teflon dosemeter and that of film dosemeters. 332 persons were controlled for the experiment. A phantom was irradiated simultaneously by X and gamma radiation. The experience in application of thermoluminescent dosemeters to personnel monitoring of radiation load of a whole body and body parts using rings is described. Two Types of TL ring dosemeters for measuring X, gamma and deta radiations are presented. Advantage and shortcomings of TL dosemeters are noted

  12. Reactivity of aminodeoxyalditols and derivatives in hydrogen fluoride

    Norrild, Jens Chr.

    -closure was obstructed, were treated with hydrogen fluoride in the presence of a carboxylic acid catalyst. The products from these reactions, including 2,6-anhydrides, were assigned. In case of 1-amino-1,6-dideoxy- or 1-benzylamino-1,3,6-trideoxy-hexitols very efficient and regioselective conversions to the......Reactions of a series of aminodeoxy-pentitols and -hexitols in anhydrous hydrogen fluoride with formic acid as catalyst gave the corresponding 2,5 and 3,6-anhydro-aminodeoxyhexitols respectively in yields of more than 95%. In the analogous reaction of 3-amino-3-deoxy-D-altritol a dianhydride...

  13. Stimulated Raman scattering in soft glass fluoride fibers

    Petersen, Christian; Dupont, Sune; Agger, Christian; Thøgersen, Jan; Bang, Ole; Keiding, Søren Rud

    2011-01-01

    We have measured the absolute Raman gain spectrum in short fluoride soft glass fibers with a pump wavelength of 1650nm. We found a peak gain of gR ¼ 4:0 2 × 10−14mW−1.......We have measured the absolute Raman gain spectrum in short fluoride soft glass fibers with a pump wavelength of 1650nm. We found a peak gain of gR ¼ 4:0 2 × 10−14mW−1....

  14. The dissolution of kaolin by acidic fluoride wastes

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

    1997-01-01

    The potential use of kaolin as a lining material for the storage of acidic and acidic fluoride wastes is investigated, No significant changes are observed gravimetrically or structurally for kaolin soaked under acidic conditions down to pH 2 for periods up to 90 days, Some release of aluminium was...... noted with decreasing pH, Severe kaolin dissolution was apparent, however, when soaked in solutions less than pH 3 to 4 with a fluoride concentration of 0.05 M. Aluminium-oxygen bonding in kaolin appears to be substantially more prone to hydrofluoric acid attack than does silicon-oxygen bonding...

  15. Stimulated Raman scattering in soft glass fluoride fibers

    Petersen, Christian; Dupont, Sune Vestergaard Lund; Agger, Christian; Thøgersen, Jan; Bang, Ole; Keiding, Søren Rud

    2011-01-01

    We have measured the absolute Raman gain spectrum in short fluoride soft glass fibers with a pump wavelength of 1650 nm. We found a peak gain of gR=4.0±2×10−14 m W−1.......We have measured the absolute Raman gain spectrum in short fluoride soft glass fibers with a pump wavelength of 1650 nm. We found a peak gain of gR=4.0±2×10−14 m W−1....

  16. Study by thermochromatography of fluorides of transuranium elements

    Thermochromatography was made suitable for fluoride study. So, an investigation of actinide tetrafluorides was accomplished from uranium to californium. Pentavalent and hexavalent fluorospecies of uranium, neptunium, plutonium and ruthenium were studied. Some new compounds have been identified in gaseous phase, whose: PuF5, PuOF3 and PaOF3. Furthermore, some presomptions as for the existence in gaseous phase of EsF4 and of an heptavalent fluorospecies of plutonium have been established. An important analogy between plutonium and ruthenium behaviour with fluorine have been shown, these results could explain the difficulties encountered in the fluoride-volatility processes

  17. Ion-assisted deposition of yttrium fluoride as a substitute for thorium fluoride: application to infrared antireflection coating on germanium

    Robic, Jean-Yves; Rolland, Bernard; Deutsch, Jean-Claude; Gallais, Patrick

    1994-11-01

    Yttrium fluoride has been proposed as a substitute for thorium fluoride in anti-reflection coatings for the infrared range. We have studied the ion assisted deposition (IAD) of YF3 in order to obtain dense and low absorbency layers in the 8 to 12 mm spectral window. Refractive index and extinction coefficient of this fluoride were determined from spectrophotometry measurements. We have then associated the YF3 with ZnS and Ge layers so as to obtain four layer anti-reflection coatings on germanium. The stress induced by each layer in the coating was measured and the sum was shown to be equal to the stress of the total coating. Eventually, an industrial, high efficiency, both side anti-reflection coating on germanium was developed using IAD YF3 film.

  18. EFFECT OF DAILY FLUORIDE EXPOSURE ON FLUORIDE RELEASE BY HIGH STRENGTH GLASS IONOMER RESTORATIVE MATERIAL USED WITH ATRAUMATIC RESTORATIVE TECHNIQUE: AN IN VITRO STUDY

    Hegde Mithra N.

    2012-04-01

    Full Text Available An in-vitro study was done to evaluate the effect of fluoride exposure, fluoride release and recharging capability by High strength Glass Ionomer restorative material used with Atraumatic restorative technique. 20 specimens were divided into four groups of five specimens each. The results showed that High strength Glass ionomer cements (Fuji IX release fluoride, the greatest release takes place between 24- 48 hours.High viscous High Strength Glass ionomer cements have the ability to recharge by external sources like fluoridated dentifrices and varnishes and thus acts as a fluoride reservoir. The recommendation that individuals with a high caries rate and glass ionomer restoration should have fluoride treatment with dentifrice and varnish seems appropriate.

  19. Extraction of tantalum (5) and niobium (5) by octanol from fluoride and fluoride-sulfuric acid solutions

    Extractability of octanol and tributylphosphate in the processes of tantalum (5) and niobium (5) extraction from their concentrated fluoride and fluoride-sulfuric acid solutions, as well as in the course of tantalum (5) and niobium (5) separation and purification, was compared. The use of octanol in the extraction technology of tantalum (5) and niobium (5) separation was shown to be effective. Stability of the extractant in long-time contact with process solutions was pointed out among its important advantages. A flowsheet of extractional separation and purification of niobium (5) and tantalum (5) using octanol, which permits preparation of the elements pure oxides, was proposed

  20. Fluoride content in bottled drinking waters, carbonated soft drinks and fruit juices in Davangere city, India

    Thippeswamy H; Kumar Nanditha; Anand S; Prashant G; Chandu G

    2010-01-01

    Background: The regular ingestion of fluoride lowers the prevalence of dental caries. The total daily intake of fluoride for optimal dental health should be 0.05-0.07 mg fluoride/kg body weight and to avoid the risk of dental fluorosis, the daily intake should not exceed a daily level of 0.10 mg fluoride/kg body weight. The main source of fluoride is from drinking water and other beverages. As in other countries, consumption of bottled water, juices and carbonated beverages has increased in o...

  1. On the assessment of hydroxyapatite fluoridation by means of Raman scattering

    Hydroxyapatite is the main mineral component of bones and teeth. Fluorapatite, a bioceramic that can be obtained from hydroxyapatite by chemical substitution of the hydroxide ions with fluoride, exhibits lower mineral solubility and larger mechanical strength. Despite the widespread use of fluoride against caries, a reliable technique for unambiguous assessment of fluoridation in in vitro tests is still lacking. Here we present a method to probe fluorapatite formation in fluoridated hydroxyapatite by combining Raman scattering with thermal annealing. In synthetic minerals, we found that effectively fluoride substituted hydroxyapatite transforms into fluorapatite only after heat treatment, due to the high activation energy for this first order phase transition.

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

    Ismail, Zainab Z; AbdelKareem, Hala N

    2015-11-01

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

  3. Fluoride rechargability of a non-resin auto-cured glass ionomer cement from a fluoridated dentifrice: An in vitro study

    A Rao

    2011-01-01

    Full Text Available Background: In addition to their fluoride-releasing properties, glass ionomer cement (GICs have the ability to reuptake and release fluorides from commonly used sources like fluoridated dentifrices. This property has the potential to provide a continuous low concentration of fluoride in the saliva aiding in caries prevention. The superior fluoride-recharging abilities of resin-modified GICs over conventional GICs have been documented. The manufacturer of a non-resin, auto-cured GIC (GC Fuji VII claims fluoride release from the product to be about six times that of conventional GIC. It was hypothesized that perhaps this high fluoride release could translate into a high reuptake and release, when exposed to a 1 000 ppm fluoridated dentifrice every day, thus providing increased fluoride levels in saliva. Aims: This study therefore examined fluoride-recharging abilities of the non-resin, auto-cured glass ionomer cement from a 1 000 ppm fluoridated dentifrice and compared it with resin-modified glass ionomer cement. Materials and Methods: Twelve glass ionomer discs each of resin-modified glass ionomer cement (GC Fuji II L C, Group 1 and the non-resin, auto-cured glass ionomer cement (GC Fuji VII, Group 2 were prepared with precise dimensions of 9 x 2 mm. The 12 specimens in each group were further subdivided into two subgroups of six each. Subgroup A involved no fluoride treatment (Control. Subgroup B involved application of a 1 000 ppm dentifrice for 2 minutes twice daily with a soft toothbrush. The disc-specimens were then suspended in airtight plastic bottles containing exactly 20 ml double distilled water. The fluoride concentration of the water in which the specimen discs were immersed was measured by means of a fluoride ion selective electrode connected to an ion selective electrode meter/digital ion analyzer at 1, 2, 7, 15, and 30 days. Statistical Analysis: It was performed using the Kruskal-Wallis Test. Results and Conclusion: Fuji VII

  4. Latest developments in non-fluoridated remineralizing technologies

    M Goswami

    2012-01-01

    Full Text Available The goal of modern dentistry is to manage non-cavitated carious lesions non-invasively through remineralization in an attempt to prevent disease progression, and to improve strength, esthetics, and function of teeth. The emphasis currently is being given to new technologies for enamel remineralization which suggest the changes in the understanding of dental caries. The aim of this paper is to review the contemporary non-fluoridated systems available for remineralization therapy and ideas for their implementation into clinical practice. A search of articles from "Pubmed" and "Medline" with the keywords Remineralization-demineralization, Casein derivatives, Non-fluoridated remineralizing agents was conducted. A total of 526 abstracts were collected, out of which 172 articles that discussed current technologies of non-fluoridated remineralizing agents were read and 33 most relevant articles were included in this paper. Casein phosphopeptide based technology has been established as a strong non-fluoridated remineralizing agent fulfilling all the criteria of an ideal remineralizing material.

  5. Effects of sodium fluoride on immune response in murine macrophages.

    De la Fuente, Beatriz; Vázquez, Marta; Rocha, René Antonio; Devesa, Vicenta; Vélez, Dinoraz

    2016-08-01

    Excessive fluoride intake may be harmful for health, producing dental and skeletal fluorosis, and effects upon neurobehavioral development. Studies in animals have revealed effects upon the gastrointestinal, renal and reproductive systems. Some of the disorders may be a consequence of immune system alterations. In this study, an in vitro evaluation is made of fluoride immunotoxicity using the RAW 264.7 murine macrophage line over a broad range of concentrations (2.5-75mg/L). The results show that the highest fluoride concentrations used (50-75mg/L) reduce the macrophage population in part as a consequence of the generation of reactive oxygen and/or nitrogen species and consequent redox imbalance, which in turn is accompanied by lipid peroxidation. A decrease in the expression of the antiinflammatory cytokine Il10 is observed from the lowest concentrations (5mg/L). High concentrations (50mg/L) in turn produce a significant increase in the proinflammatory cytokines Il6 and Mip2 from 4h of exposure. In addition, cell phagocytic capacity is seen to decrease at concentrations of ≥20mg/L. These data indicate that fluoride, at high concentrations, may affect macrophages and thus immune system function - particularly with regard to the inflammation autoregulatory processes, in which macrophages play a key role. PMID:26965474

  6. Fluoride volatility technology for reprocessing of irradiated oxide fuel

    A review of the scientific research works in the VNIIKhT on the spent oxide fuel reprocessing by the fluoride volatility technology is presented. Refining feasibilities of the basic stages of the fluoride volatility technology were investigated. Possibility of the release of the basic part of fission products with cinders on the fluorination stage was supported by the experimental results. Application of the fluorine sorbents (NaF, BaF2) means for the summary coefficient of the UF6 purification from fission products at a level of 107. Possibility of the deep plutonium recovery from the oxide fuel was shown. Results of the investigations into pyrohydrolysis of UF6 and mixture of UF6 and PuF6 with the oxide granulates production of the needed density with the content of fluorine 0.005 mass. % and oxygen coefficient 2 - 2.1 are performed. Recommendations on the fluoride volatility process application for the spent oxide fuel reprocessing of fast and light water reactors and prediction on the closed fuel cycle using fluoride volatility process were given with regard to new demands on fission products nonproliferation

  7. Some analytical aspects of the technologies using molten fluorides

    Analytical activities accompanying the development or a molten fluoride reactor can be divided into 3 groups: (i) Balance analyses of fissile and fertile isotopes and their isotope composition; (ii) Analytical control of the reactor process; and (iii) Special analyses and measurements for physical reactor parameters determination. The first group is formed by the precise determination of U, Pu, Th content and isotope composition. Both destructive and non-destructive methods are recommended. The suitable methods are the following: chemical methods (e.g. titrimetric methods), x-ray fluorescence and IDA with alpha- or mass-spectrometric ending. The mass-spectrometry, ICP-MS and gamma-spectrometry are preferred for the isotope analysis. The analyses important for operating reactor form the second group. There is the determination of important activation and fission products as: 233Pa, 137Cs, 90Sr, 144Ce, rare earth elements, transuranium elements, tritium etc. The methods commonly used are based on gamma-spectrometry, alpha-spectrometry, ICP-MS and LSC. In the last group the analyses used for the determination of reactor parameters or the chemical form of some elements in the melt of fluorides can be included. As an example the mass-spectrometric determination of the capture-to-fission ratio or the use of FTIR spectrometry for the determination of the chemical form of fluoride melt. The paper describes the results of measurements obtained for the systems similar to fluoride melts. The possibility of the methods application is discussed. (author)

  8. Efficacy of xylitol and fluoride mouthrinses on salivary mutans streptococci

    Arunakul, Malee; Thaweboon, Boonyanit; Thaweboon, Sroisiri; Asvanund, Yuwadee; Charoenchaikorn, Kesinee

    2011-01-01

    Objective To evaluate the level of salivary Mutans streptococci (MS) after rinsing with xylitol, fluoride, and a combination of xylitol and fluoride solutions, compared with distilled water. Methods Eighty healthy 8-9 years old subjects with high level of MS (> 105 CFU/mL) were equally divided into 4 groups. Subjects rinsed their mouths for 1 min with 10 mL of 0.05% (w/v) sodium fluoride (NaF), 12.5% (w/v) xylitol or 0.05% (w/v) NaF + 12.5% (w/v) xylitol 3 times daily over 10 weeks. Distilled water rinsed group served as a control. Paraffin-stimulated whole saliva samples were collected at baseline, 5 weeks, and 10 weeks after rinsing to determine the level of salivary MS by culturing on Mitis Salivarius Bacitracin agar. The statistical significance was calculated by Kruskal Wallis, Mann Whitney U, and Wilcoxon signed-rank tests at a significant level of P< 0.05. Results Significant reductions in MS count were observed in subjects using 0.05% NaF + 12.5% xylitol over other groups within 5 weeks and after 10 weeks and 12.5% xylitol alone after 10 weeks compared with baseline. Conclusions The present study provides evidence for the inhibitory effect of xylitol, used in combination with fluoride, delivered in the form of mouthrinse, on salivary MS in the group of schoolchildren. PMID:23569819

  9. Fluoride Varnish for Caries Prevention: Efficacy and Implementation.

    Bonetti, Debbie; Clarkson, Jan E

    2016-01-01

    Many reviews support fluoride varnish (FV) as a caries-inhibitory agent. Evidence from 6 Cochrane systematic reviews involving 200 trials and more than 80,000 participants further confirms the effectiveness of FV, applied professionally 2-4 times a year, for preventing dental caries in both primary and permanent teeth. The relative benefit of FV application seems to occur irrespective of baseline caries risk, baseline caries severity, background exposure to fluorides, use of fluoride toothpaste and application features such as prior prophylaxis, concentration of fluoride or frequency of application. While the efficacy of FV is acknowledged in clinical practice guidelines globally, the implementation of this recommendation may still be an issue. Factors that may facilitate FV application in the USA include Medicaid eligibility, relationships with dentists/community centers and strong cooperation and communication between physicians and support staff. Barriers include insufficient time to integrate oral health services into well-child visits, difficulty in applying FV (lack of skills/training) and resistance among colleagues and staff. Research in the UK/Scotland also suggests encouraging clinicians in their motivation to perform this treatment and addressing professional and parental concerns relating to possible negative consequences may be influential. Further research targeting cost-effectiveness and how FV in routine care may fit in with political agendas relating to, for example, inequalities in health care provision and access will also play a key part in stakeholder decisions to put resources into this issue. PMID:27100219

  10. Synthesis and characterization of uranium(VI) chloride fluorides

    Uranium (VI) chloride fluorides were synthesized by the reaction of liquid HCl and solid UF6 between -80 and -114 deg C. These dark red compounds are unstable above -40 to -60 deg C. The simplest formulas derived from compositional analysis are UF5Cl and UF4Cl2. (author)

  11. ADEQUACY OF SAMPLING TRAINS AND ANALYTICAL PROCEDURES USED FOR FLUORIDE

    Liquid nitrogen-cooled cold-traps were used to establish the collection efficiency for fluorides of two different source sampling trains at primary aluminum reduction plants and wet-process phosphoric acid plants. It was found that the glass frit filter support commonly used in s...

  12. Transference system of gaseous fluoride compounds for infrared spectrofotometric analysis

    A vacuum line design for transference of gaseous fluoride compounds involved in the uranium hexafluoride infrared analysis is presented. The text include specific comments about the characteristics of each component and about the possibilities of its acquisition in the national market. (author)

  13. Bioethical considerations about water fluoridation: a critical review.

    María Elisa Quinteros

    2016-08-01

    Full Text Available Dental caries is one of the oral pathologies with greater burden of disease in the Chilean population. Fluoridation of drinking water has been used as a caries prevention strategy. However, its application as a public policy has been questioned since its implementation. The aim of this article is to analyze whether fluoridation of drinking water is a justified measure in reducing the incidence and prevalence of caries from the perspective of bioethics, taking into account the current evidence on its effectiveness. The arguments reviewed are based on the belief that water fluoridation is effective and, in general terms, ethically acceptable. A recent systematic review concludes that there is not enough evidence to support fluoridation as a public policy. There is a gap of knowledge that ought to be closed so that public health authorities can assess the significance of the intervention and make a democratic decision on its continuation or suspension based on scientific evidence. This decision should be informed and disseminated within the community.

  14. Removal of fluoride contamination in water by three aquatic plants.

    Karmakar, Sukalpa; Mukherjee, Joydeep; Mukherjee, Somnath

    2016-01-01

    Phytoremediation, popularly known as 'green technology' has been employed in the present investigation to examine the potential of fluoride removal from water by some aquatic plants. Fluoride contamination in drinking water is very much prevalent in different parts of the world including India. Batch studies were conducted using some aquatic plants e.g., Pistia stratiotes, Eichhornia crassipes, and Spirodela polyrhiza which profusely grow in natural water bodies. The experimental data exhibited that all the above three aquatic floating macrophytes could remove fluoride to some relative degree of efficiency corresponding to initial concentration of fluoride 3, 5, 10, 20 mg/l after 10 days exposure time. Result showed that at lower concentration level i.e., 3 mg/L removal efficiency of Pistia stratiotes (19.87%) and Spirodela polyrhiza (19.23%) was found to be better as compared to Eichhornia crassipes (12.71%). Some of the physiological stress induced parameters such as chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, total protein, catalase, and peroxidase were also studied to explore relative damage within the cell. A marginal stress was imparted among all the plants for lower concentration values (3 mg/L), whereas at 20 mg/l, maximum damage was observed. PMID:26247406

  15. BEHAVIORAL CHANGES IN CATLA CATLA DUE TO FLUORIDATED TOOTHPASTE

    Akhilesh Verma

    2015-08-01

    Full Text Available Asmall project was carried out on behavioral Aalteration in Catla catla due to toothpaste which contained fluoride as one of the content. The behavioral changes in feeding, swimming movement, body orientation, opercular activity, gulping activity, mucus secretion and body coloration were observed.

  16. Slow-release fluoride devices: a literature review

    Juliano Pelim Pessan

    2008-08-01

    Full Text Available Although the prevalence of caries has decreased dramatically over the past decades, it has become a polarised disease, with most of subjects presenting low caries levels and few individuals accounting for most of the caries affected surfaces. Thus it become evident for the need of clinical approaches directed at these high-risk patients, in order to overcome problems related to compliance and low attendance at dental care centres. Slow-release fluoride devices were developed based on the inverse relationship existing between intra-oral fluoride levels and dental caries experience. The two main types of slow-release devices - copolymer membrane type and glass bead - are addressed in the present review. A substantial number of studies have demonstrated that these devices are effective in raising intra-oral F concentrations at levels able to reduce enamel solubility, resulting in a caries-protective effect. Studies in animals and humans demonstrated that the use of these devices was able to also protect the occlusal surfaces, not normally protected by conventional fluoride regimens. However, retention rates have been shown to be the main problem related to these devices and still requires further improvements. Although the results of these studies are very promising, further randomised clinical trials are needed in order to validate the use of these devices in clinical practice. The concept of continuously providing low levels of intra-oral fluoride has great potential for caries prevention in high caries-risk groups.

  17. Progress in development of Fluoride volatility reprocessing technology

    Uhlir, Jan; Marecek, Martin [Nuclear Research Institute Rez plc, CZ-250 68 Husinec - Rez 130 (Czech Republic); Precek, Martin [Nuclear Research Institute Rez plc, CZ-250 68 Husinec - Rez 130 (Czech Republic); Oregon State University, Corvallis, Oregon (United States)

    2008-07-01

    Fluoride Volatility Method is based on direct fluorination of powdered spent fuel with fluorine gas in a flame fluorination reactor, where the volatile fluorides (represented mainly by UF{sub 6}, partially NpF{sub 6}) are separated from the non-volatile ones (e.g. PuF{sub 4}, AmF{sub 3}, CmF{sub 3}, fluorides of majority of fission products). The method is regarded to be a promising advanced pyrochemical technology mainly for selected spent oxide fuels of advanced LWRs or Generation-IV fast reactors. The technology should be chiefly suitable for the reprocessing of advanced oxide fuels with inert matrices of very high burn-up and short cooling time, which can be hardly reprocessed by hydrometallurgical technologies. The current research and development work in the area of Fluoride Volatility Method is focused to the experimental program carried out at the semi-technological line called FERDA placed in radiochemical labs of the Nuclear Research Institute of the Czech Republic. (authors)

  18. Progress in development of Fluoride volatility reprocessing technology

    Fluoride Volatility Method is based on direct fluorination of powdered spent fuel with fluorine gas in a flame fluorination reactor, where the volatile fluorides (represented mainly by UF6, partially NpF6) are separated from the non-volatile ones (e.g. PuF4, AmF3, CmF3, fluorides of majority of fission products). The method is regarded to be a promising advanced pyrochemical technology mainly for selected spent oxide fuels of advanced LWRs or Generation-IV fast reactors. The technology should be chiefly suitable for the reprocessing of advanced oxide fuels with inert matrices of very high burn-up and short cooling time, which can be hardly reprocessed by hydrometallurgical technologies. The current research and development work in the area of Fluoride Volatility Method is focused to the experimental program carried out at the semi-technological line called FERDA placed in radiochemical labs of the Nuclear Research Institute of the Czech Republic. (authors)

  19. Effect of fluoride and chlorhexidine digluconate mouthrinses on plaque biofilms

    Rabe, Per; Twetman, Svante; Kinnby, Bertil;

    2015-01-01

    pre-molar region were worn by three subjects for 7 days. Control discs were removed before subjects rinsed with 0.1% chlorhexidine digluconate (CHX) or 0.2% sodium fluoride (NaF) for 1 minute. Biofilms were stained with Baclight Live/Dead and z-stacks of images created using confocal scanning laser...

  20. Mortality and cancer morbidity after heavy occupational fluoride exposure

    Grandjean, P; Juel, K; Jensen, Ole Møller

    1985-01-01

    A cohort of 431 male cryolite workers employed for at least six months between 1924 and 1961 was identified from personnel records at the Copenhagen cryolite factory. During this period, heavy fluoride exposure resulted in at least 74 cases of skeletal fluorosis. All workmen in the cohort were fo...

  1. Mathematical model of desublimation process of volatile metal fluorides

    Smolkin, P. А.; Buynovskiy, А. S.; Lazarchuk, V. V.; Matveev, А. А.; Sofronov, V. L.

    2007-01-01

    Mathematical model for calculation of optimal temperature desublimation in metal fluorides and the number of desublimation stages has been developed; it permits achieving the degree of base product recovery from gas-vapour mixture nearly to 100 %. Experimental checking of modeling results at uranium hexafluoride desublimation shows a good correlation with the theoretical data.

  2. Spectral-luminescent properties of zirconium fluoride glass with holmium

    Luminescent spectra of Ho containing zirconium fluoride glasses are the subject of the paper. ZrF4 glasses has a minimum of own losses in region of 2 μm. They are convenient for activation with Ho3+ ions which posses an intensive luminescence in this region (5I7→5I8 transition). (author)

  3. Electrodeposition of transuranic elements in molten fluoride media

    Huguet, Anne; Bourg, Stephane; Lacquement, Jerome [CEA Marcoule, DEN/DRCP/SCPS/LPP, Bat. 399, B.P. 17171, 30207 Bagnols-sur-Ceze (France); Ghetta, Veronique [IN2P3/LPSC, UMR 5821, 38026 Grenoble Cedex 1 (France); Fouletier, Jacques [ENSEEG/LEPMI, UMR 5631, B.P. 75, 38402 Saint Martin d' Heres (France)

    2008-07-01

    The aim of this work is to evaluate the performance of an electrolytic pyrochemical process for the An-Ln separation in molten fluoride media. The attempts of electrodeposition would be performed onto liquid bismuth. Additionally, this work represents an advance in the electrolytic methods as far as the electrolysis would be carried out onto a dropping bismuth electrode. (authors)

  4. Een ionchromatografische methode voor de bepaling van fluoride in water

    Beld WA van den; Cleven RFMJ; Neele J; LAC

    1998-01-01

    Dit rapport bevat resultaten van het onderzoek naar het ontwikkelen van een geautomatiseerde ionchromatografische methode voor de bepaling van fluoride, acetaat en formiaat in diverse waterige milieu's. Het onderzoek heeft geresulteerd in een betrouwbare, selectieve en gevoelige methode vo

  5. THE USE OF FLUORIDE CONTAINING MINERAL WATER IN WORT PRODUCTION

    Gunka Yonkova

    2011-12-01

    Full Text Available The present work aims to study the quality of wort produced using fluoride containing mineral water. The results show that the mineral water has a negative impact on the enzymatic destruction of starch, proteins, color intensity and pH of the wort. The changes of pH during mashing process using tap and mineral water was studied. The lower acidity of wort obtained using mineral water didn’t change during the brewing process. The fluoride content of beer is lower than 5 mg.L-1 when wort is produced using mineral and tap water in 1:1 ratio and citric acid for pH correction. At the same time, the final degree of fermentation, α-amine nitrogen content and the intensity of color of produced wort are close to the control sample. The changes in fluoride ion concentration are monitored using ion-selective potentiometry. The fluoride content is decreased from 5.7 to 4.75 mg.L-1, the most intense change is observed during the mashing process.

  6. CAN FLUORIDATION AFFECT WATER LEAD LEVELS AND LEAD NEUROTOXICITY?

    Recent reports have attempted to show that certain approaches to fluoridating potable water is linked to increased levels of lead(II) in the blood. We examine these claims in light of the established science and critically evaluate their significance. The completeness of nexafluo...

  7. Efficacy of xylitol and fluoride mouthrinses on salivary mutans streptococci

    Sroisiri Thaweboon; Yuwadee Asvanund; Kesinee Charoenchaikorn

    2011-01-01

    To evaluate the level of salivary Mutans streptococci (MS) after rinsing with xylitol, fluoride, and a combination of xylitol and fluoride solutions, compared with distilled water. Methods: Eighty healthy 8-9 years old subjects with high level of MS (> 105 CFU/mL) were equally divided into 4 groups. Subjects rinsed their mouths for 1 min with 10 mL of 0.05% (w/v) sodium fluoride (NaF), 12.5% (w/v) xylitol or 0.05% (w/v) NaF + 12.5% (w/v) xylitol 3 times daily over 10 weeks. Distilled water rinsed group served as a control. Paraffin-stimulated whole saliva samples were collected at baseline, 5 weeks, and 10 weeks after rinsing to determine the level of salivary MS by culturing on Mitis Salivarius Bacitracin agar. The statistical significance was calculated by Kruskal Wallis, Mann Whitney U, and Wilcoxon signed-rank tests at a significant level ofP< 0.05. Results: Significant reductions in MS count were observed in subjects using 0.05% NaF+ 12.5% xylitol over other groups within 5 weeks and after 10 weeks and 12.5% xylitol alone after 10 weeks compared with baseline. Conclusions: The present study provides evidence for the inhibitory effect of xylitol, used in combination with fluoride, delivered in the form of mouthrinse, on salivary MS in the group of schoolchildren.

  8. Effects of amine fluoride on biofilm growth and salivary pellicles

    Van der Mei, HC; Engels, E; de Vries, Jacob; Busscher, HJ

    2008-01-01

    The amine fluoride (AmF) N'-octadecyltrimethylendiamine-N, N,N'-tris(2-ethanol)-dihydrofluoride is a cationic antimicrobial which can have beneficial effects on plaque formation. Here, we determine changes in pellicle and bacterial cell surface properties of the strains Actinomyces naeslundii HM1, S

  9. Evaluation and modeling of the parameters affecting fluoride toxicity level in aquatic environments by bioassay method

    Hamid Reza Shamsollahi

    2014-04-01

    Full Text Available Background: Fluoride exists in various forms in nature and water resources. , The rising level of fluoride in water resources due to discharge of industrial effluents can cause toxicity in aquatic organisms. To prevent toxicity, it is necessary to determine maximum fluoride toxicity as well as effluent discharge limits. The aim of this study was to determine the maximum fluoride toxicity and the factors affecting fluoride toxicity to provide a model in order to determine the effluent discharge limits. Methods: Daphnia magna bioassay in the absence of confounding factors was used to determine the maximum level of fluoride toxicity. Then, bioassay was repeated in the presence of the confounding factors (hardness, temperature and exposure time to determine their effects. Results: In the absence of intervening factors, fluoride LC50 levels determined after 24, 48 and 72 hours exposure were 4.9, 46.5 and 38.7 mg/l, respectively.. Also, the influence of confounding factors on LC50 values was reported significant by Minitab software. Conclusion: Increasing the water hardness reduced fluoride toxicity, and increasing the water temperature and exposure time increased fluoride toxicity in aquatic environments. Therefore, while determining the wastewater discharge limit in terms of fluoride concentration, it is essential to take the effect of confounding factors on fluoride toxicity into account in order to prevent toxicity in the open water resources.

  10. The effect of different fluoride application methods on the remineralization of initial carious lesions

    2016-01-01

    Objectives The purpose of this study was to assess the effect of single and combined applications of fluoride on the amount of fluoride release, and the remineralization and physical properties of enamel. Materials and Methods Each of four fluoride varnish and gel products (Fluor Protector, FP, Ivoclar Vivadent; Tooth Mousse Plus, TM, GC; 60 Second Gel, A, Germiphene; CavityShield, CS, 3M ESPE) and two fluoride solutions (2% sodium fluoride, N; 8% tin(ii) fluoride, S) were applied on bovine teeth using single and combined methods (10 per group), and then the amount of fluoride release was measured for 4 wk. The electron probe microanalysis and the Vickers microhardness measurements were conducted to assess the effect of fluoride application on the surface properties of bovine teeth. Results The amount of fluoride release was higher in combined applications than in single application (p < 0.05). Microhardness values were higher after combined applications of N with FP, TM, and CS than single application of them, and these values were also higher after combined applications of S than single application of A (p < 0.05). Ca and P values were higher in combined applications of N with TM and CS than single application of them (p < 0.05). They were also increased after combined applications of the S with A than after single application (p < 0.05). Conclusions Combined applications of fluoride could be used as a basis to design more effective methods of fluoride application to provide enhanced remineralization. PMID:27200280

  11. Fluoride stimulates [3H]thymidine incorporation and alkaline phosphatase production by human osteoblasts

    The effect of sodium fluoride on alkaline phosphatase (ALP) release and [3H]thymidine uptake by human osteoblasts in culture was investigated. Sodium fluoride stimulated both ALP release and [3H]thymidine uptake at concentrations of sodium fluoride greater than 250 mumol/L. This stimulation was similar in magnitude to that induced by 1,25-dihydroxycholecalciferol. The fluoride-induced increase in ALP was inhibited by verapamil, a calcium channel blocker. We conclude that sodium fluoride stimulates osteoblasts to proliferate and to release ALP. This stimulation by fluoride is dependent on calcium influx. Fluoride-induced stimulation of human osteoblasts may be relevant to its effect in enhancing bone formation in patients with osteoporosis

  12. Pit and fissure sealants versus fluoride varnishes for preventing dental decay in children and adolescents

    Hiiri, Anne; Ahovuo-Saloranta, Anneli; Nordblad, Anne;

    2010-01-01

    BACKGROUND: The majority of the detected increment in dental caries among children and adolescents is confined to pit and fissure surfaces of first molars. OBJECTIVES: The objective of this study was to compare the effectiveness of pit and fissure sealants with fluoride varnishes in the prevention......-up found significantly more caries on the fluoride varnished tooth surfaces, compared to sealed plus fluoride varnished surfaces, with a RR of 0.36 (95% CI 0.21 to 0.61). AUTHORS' CONCLUSIONS: There was some evidence on the superiority of pit and fissure sealants over fluoride varnish application in the...... design; sealants versus fluoride varnish or sealants and fluoride varnish combination versus fluoride varnish alone; and subjects under 20 years of age. The primary outcome of interest was the increment in the numbers of carious occlusal surfaces of permanent premolars and molars. DATA COLLECTION AND...

  13. Fluoride concentrations in dental plaque and saliva after the use of a fluoride dentifrice preceded by a calcium lactate rinse.

    Pessan, Juliano P; Sicca, Cristina M; de Souza, Tatiana S; da Silva, Salete M B; Whitford, Gary M; Buzalaf, Marília A R

    2006-12-01

    Plaque fluoride concentrations ([F]) are directly related to plaque calcium concentrations [Ca]. Attempts to increase plaque F uptake from dentifrices or rinses have used methods designed to increase plaque [Ca] but with inconsistent results. This double-blind, double-crossover study tested the effect of a 150 mM calcium lactate rinse used prior to brushing with placebo or fluoridated dentifrices (1030 p.p.m. as NaF) on plaque and salivary [F] and [Ca]. Sixteen children (8-10 yr of age) were randomly assigned to four different groups according to the four treatments (placebo dentifrice or fluoridated dentifrice preceded by calcium lactate or deionized water prerinses). Plaque and saliva were collected 1 and 12 h after brushing on day 7 after starting to use the dentifrices. F was determined using the electrode and Ca was determined using atomic absorption spectrometry. Plaque and salivary [Ca] were not significantly increased after use of the calcium lactate prerinse, except for plaque [Ca] 1 h after the use of the placebo dentifrice. A significant increase in salivary [F] was associated with the calcium lactate prerinse only at 1 h after the use of the fluoridated dentifrice. The the calcium lactate prerinse did not significantly affect plaque [F] under any condition. PMID:17184230

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

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

    2016-07-01

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

  15. Effect of a 5000 ppm fluoride toothpaste and a 250 ppm fluoride mouth rinse on the demineralisation of dentin surfaces

    Altenburger Markus J

    2009-07-01

    Full Text Available Abstract Background The purpose of this study was to test the null hypothesis that there is no difference between the effect of (1 a 5000 ppm fluoride toothpaste, and (2 a 250 ppm fluoride mouth rinse on demineralized human dentin surfaces, against the alternative hypothesis of a difference. Findings Dentin specimens were obtained from the cervical regions of 45 extracted human third molars. Half the surface of each specimen was sealed with a self-etching adhesive system and served as the reference surface. The dentin specimens were randomly assigned to one of the three groups, 5000 ppm fluoride toothpaste (Duraphat, 250 ppm fluoride mouth rinse (Meridol and distilled water (negative control. An intraoral appliance was made for one volunteer. In each test cycle, 15 specimens were inserted in the appliance and worn for 24 hours a day, over a period of three weeks. Once daily, the appliance was immersed in the agent being tested; either toothpaste slurry, mouth rinse or distilled water for 60 seconds. Demineralization was assessed in terms of lesion depth (μm and mineral loss (vol. % × μm by transversal microradiography. Data analysis was accomplished using Kolmogorov-Smirnov test and ANOVA (SPSS 12.0. Statistically significant differences for mineral loss and lesion depth were found between the toothpaste and the mouth rinse as well as between the toothpaste and the control group, but not between the mouth rinse and the control group. Conclusion Within the limitations of this study, the results suggest that treatment of demineralised dentin with a toothpaste containing 5000 ppm fluoride may considerably reduce mineral loss and lesion depth on exposed dentin.

  16. Effect of High Water Fluoride Concentration on the Intellectual Development of Children in Makoo/Iran

    M Shadfar

    2012-01-01

    Full Text Available Objective: Prolonged excessive intake of fluoride during child’s growth and development stages has been associated with mental and physical problems.The aim of this study was to investigate the effect of excessive fluoride intake on the intelligence quotient (IQ of children living in five rural areas in Makoo/Iran.Materials and Methods: In this cross-sectional study, 293 children aged 6-11 years were selected from five villages in Makoo with normal fluoride (0.8±0.3 ppm, medium fluoride (3.1±0.9 ppm and high fluoride (5.2±1.1 ppm in their water supplies. The IQ of each child was measured by the Raven’s test. Educational and residential information and the medical history of each child was recorded by a questionnaire completed by the parents. Data were analyzed by ANOVA test with a significance level of 0.05.Results: The mean IQ scores decreased from 97.77±18.91 for the normal fluoride group to 89.03±12.99 for the medium fluoride group and to 88.58±16.01 for the high fluoride group (P=0.001.Conclusion: Children residing in areas with higher than normal water fluoride levels demonstrated more impaired development of intelligence. Thus, children’s intelligence may be affected by high water fluoride levels.

  17. The effect of water purification systems on fluoride content of drinking water

    Prabhakar A

    2008-03-01

    Full Text Available Objective: The purpose of the present study was to determine the effect of different water purification systems on the fluoride content of drinking water and to compare the efficacy of these water purification systems in reducing the fluoride content. Materials and Methods: Five different water purification systems were tested in this study. They were reverse osmosis, distillation, activated carbon, Reviva ® , and candle filter. The water samples in the study were of two types, viz, borewell water and tap water, these being commonly used by the people of Davangere City, Karnataka. The samples were collected before and after purification, and fluoride analysis was done using fluoride ion-specific electrode. Results: The results showed that the systems based on reverse osmosis, viz, reverse osmosis system and Reviva ® showed maximum reduction in fluoride levels, the former proving to be more effective than the latter; followed by distillation and the activated carbon system, with the least reduction being brought about by candle filter. The amount of fluoride removed by the purification system varied between the system and from one source of water to the other. Interpretation and Conclusion: Considering the beneficial effects of fluoride on caries prevention; when drinking water is subjected to water purification systems that reduce fluoride significantly below the optimal level, fluoride supplementation may be necessary. The efficacy of systems based on reverse osmosis in reducing the fluoride content of water indicates their potential for use as defluoridation devices.

  18. Effect of different frequencies of fluoride dentifrice and mouthrinse administration: an in situ study

    Daniela Correia Cavalcante Souza

    2010-12-01

    Full Text Available The effect of a combination of topical fluoridation methods for inhibition of enamel demineralization in the face of a cariogenic challenge has not been clearly established. This in situ crossover study aimed to assess whether the addition of daily use of fluoride mouthrinse (FR to that of fluoride dentifrice (FD is equivalent to increasing the frequency of FD application in terms of the effect on enamel demineralization and fluoride content. Over 3 phases of 14 days each, 12 volunteers wore appliances containing enamel blocks exposed to a 20 % sucrose solution 8 times/day. During each phase the blocks underwent one of the following treatments: 2x/day FD, 2x/day FD + 1x/day FR, and 3x/day FD. The blocks were assessed for hardness and fluoride content. Three x/day FD did not differ from 2x/day + 1x/day FR, however it enhanced demineralization protection when compared to 2x/day FD. All treatments produced an increase in enamel fluoride content compared to no treatment (sound blocks (p < 0.05, but the differences between them were not significant. The results of this study suggest that the daily use of fluoride mouthrinse combined with that of fluoride dentifrice has similar effects on enamel demineralization and fluoride content when compared to increasing the frequency of fluoride dentifrice use.

  19. Preparation and chemical crystallographic study of new hydrides and hydro-fluorides of ionic character

    Within the context of a growing interest in the study of reversible hydrides with the perspective of their application in hydrogen storage, this research thesis more particularly addressed the case of ternary hydrides and fluorides, and of hydro-fluorides. The author reports the development of a method of preparation of alkaline hydrides, of alkaline earth hydrides and of europium hydride, and then the elaboration of ternary hydrides. He addresses the preparation of caesium fluorides and of calcium or nickel fluorides, of Europium fluorides, and of ternary fluorides. Then, he addresses the preparation of hydro-fluorides (caesium, calcium, europium fluorides, and caesium and nickel fluorides). The author presents the various experimental techniques: chemical analysis, radio-crystallographic analysis, volumetric mass density measurement, magnetic measurements, ionic conductivity measurements, Moessbauer spectroscopy, and nuclear magnetic resonance. He reports the crystallographic study of some ternary alkaline and alkaline-earth hydrides (KH-MgH2, RbH-CaH2, CsH-CaH2, RbH-MgH2 and CsH-MgH2) and of some hydro-fluorides (CsCaF2H, EuF2H, CsNiF2H)

  20. Enhancing Fluoride: Clinical Human Studies of Alternatives or Boosters for Caries Management.

    Fontana, Margherita

    2016-01-01

    Dental caries remains a major public health problem, especially for certain high-risk population groups. The goal of this study was to assess the evidence regarding strategies meant to be used as alternatives or booster/supplements to fluoride for caries prevention and management. Articles were selected for inclusion if they had a prospective longitudinal design, with a fluoride control arm, and were conducted in human subjects. Of the included studies, 7/18 studies on calcium-based strategies favored the test product (the majority of studies included exposure of fluoride in all groups). All the arginine studies (8/8) included a combination of arginine and a calcium base, and concluded that this has the potential to significantly boost the performance of fluoride. The remaining included studies focused on the addition of microbial-related strategies to a fluoride-containing vehicle (2 xylitol studies and 1 study using a probiotic milk), and all favored the combination as a booster to fluoride. Thus, the current study did not identify evidence for any strategy to effectively be used as a substitute or alternative to fluoride, but identified some consistent evidence derived from the use of prebiotic strategies (primarily from use of arginine combined with calcium) to support their potential use to boost the mechanism of action of fluoride. Thus, fluoride-based strategies remain the standard for caries prevention and management, with some evidence that boosting the effects of fluoride by the use of prebiotic strategies is a promising possibility. PMID:27100833

  1. Protective effect of ascorbic acid and Ginkgo biloba against learning and memory deficits caused by fluoride.

    Jetti, Raghu; Raghuveer, C V; Mallikarjuna, Rao C

    2016-01-01

    Fluoride is present in the ground water, World Health Organization permitted level of fluoride in the ground water is 0.5 ppm. Tooth pastes, mouth washes, tea and sea fish are the sources of fluoride. Exposure to these multiple sources results in several adverse effects in addition to the fluorosis. The present study aimed to test the effect of vitamin C and Ginkgo biloba against the behavioural deficits caused by fluoride. Rats were divided into five groups with six animals in each group (n = 6). Control group received ordinary tap water with 0.5 ppm of fluoride, the remaining groups received 100 ppm of fluoride for 30 days prior to fluoride exposure. Two groups of animals received 100 mg/kg body weight of vitamin C and G. biloba for 15 days prior to fluoride exposure. After 45 days, behavioural studies (T-Maze, passive avoidance) were conducted on the experimental animals. The results of the present study showed no behavioural deficits in the control group of animals however, the rats that received fluoride water exhibited impairment in their spatial learning and memory deficits. The deficits are not marked in the vitamin C and G. biloba groups. To conclude chronic exposure to high levels of fluoride causes severe impairment in the spatial learning and memory, these deficits can be ameliorated with the vitamin C and G. biloba. PMID:24081631

  2. Fluoride in the drinking water of Pakistan and the possible risk of crippling fluorosis

    M. A. Tahir

    2013-02-01

    Full Text Available To explore the possibility of fluoride toxicity, 747 water samples were collected from surface water and groundwater sources of 16 major cities of Pakistan, adopting a uniform sampling design with distribution of samples: Lahore (79, Kasur (46, Faisalabad (30, Khushab (50, Chakwal (51, Mianwali (30, Jhelum (53, Bahawalpur (60, Karachi (60, Mirpur Khas (55, Peshawar (38, Risalpur (35, Quetta (81, Ziarat (21, Loralai (21, and Mastung (37. Comparison of analytical findings with WHO Guidelines of Drinking Water for Fluoride (i.e., 1.5 ppm has concluded that 16% of the monitored water sources have fluoride concentration beyond the permissible safe limit of 1.5 mg L−1 falling in the concentration range of 1.6–25 mg L−1. The highest fluoride contamination (22% is detected in the Balochistan province followed by 19% in Punjab province. Comparatively higher fluoride levels of > 20% in the groundwater sources like hand pumps supported the possibility of increased groundwater contamination as excessive fluoride concentrations are expected to come from calcium-poor aquifers and in areas where fluoride-bearing minerals are common or where cation exchange of sodium for calcium occurs. Field observations have also indicated the prevalence of fluoride-associated health implications in the study areas with excessive fluoride in water sources. Findings of this study have provided bidirectional vision for the epidemiological investigations as well as to mitigate the issues in the affected vicinities of fluoride-rich areas.

  3. Fluoride bioaccumulation by hydroponic cultures of camellia (Camellia japonica spp.) and sugar cane (Saccharum officinarum spp.).

    Camarena-Rangel, Nancy; Rojas Velázquez, Angel Natanael; Santos-Díaz, María del Socorro

    2015-10-01

    The ability of hydroponic cultures of camellia and sugar cane adult plants to remove fluoride was investigated. Plants were grown in a 50% Steiner nutrient solution. After an adaptation period to hydroponic conditions, plants were exposed to different fluoride concentrations (0, 2.5, 5 and 10 mg L(-1)). Fluoride concentration in the culture medium and in tissues was measured. In sugar cane, fluoride was mainly located in roots, with 86% of it absorbed and 14% adsorbed. Sugar cane plants removed 1000-1200 mg fluoride kg(-1) dry weight. In camellia plants the highest fluoride concentration was found in leaf. Roots accumulated fluoride mainly through absorption, which was 2-5 times higher than adsorption. At the end of the experiment, fluoride accumulation in camellia plants was 1000-1400 mgk g(-1) dry weight. Estimated concentration factors revealed that fluoride bioaccumulation is 74-221-fold in camellia plants and 100-500-fold in sugar cane plants. Thus, the latter appear as a suitable candidate for removing fluoride from water due to their bioaccumulation capacity and vigorous growth rate; therefore, sugar cane might be used for phytoremediation. PMID:25930125

  4. The interaction of polyacid-modified composite resins ("compomers" with aqueous fluoride solutions

    Reza Rohani

    2009-06-01

    Full Text Available OBJECTIVE : The aim of this study was to investigate how the release of fluoride from two compomers and a fluoridated composite resin was affected by exposure to KF solution. MATERIAL AND METHODS: Two compomers (Dyract AP and Compoglass F and one fluoridated composite (Wave were prepared as discs (6 mm diameter and 2 mm thick, curing with a standard dental lamp. They were then stored in either water or 0.5% KF for 1 week, followed by placement in water for periods of 1 week up to 5 weeks total. Fluoride was determined with and without TISAB (to allow complexed and decomplexed fluoride to be determined, and other ion release (Na, Ca, Al, Si, P was determined by ICP-OES. RESULTS: Specimens were found not to take up fluoride from 100 ppm KF solution in 24 h, but to release additional fluoride when stored for up to five weeks. Compomers released more fluoride cumulatively following exposure to KF solution (p<0.001, all of which was decomplexed, though initial (1 week values were not statistically significant for Dyract AP. Other ions showed no variations in release over 1 week, regardless of whether the specimens were exposed to KF. Unlike the compomers, Wave showed no change in fluoride release as a result of exposure to KF. CONCLUSIONS: Compomers are affected by KF solution, and release more fluoride (but not other ions after exposure than if stored in water.

  5. Effect of high fluoride concentration in drinking water on children’s intelligence

    Seraj B

    2006-07-01

    Full Text Available Background and Aim: Human and animal studies linking fluoride with diminished intelligence have been published. Although adverse effects of high intake of fluoride on intelligence and mental acuity continue to be reported, they are still controversial. The aim of this research was to investigate the relationship between fluoride in drinking water and children's intelligence. Materials and Methods: In this cross sectional study, 41 children were selected from the high fluoride area with 2.5mg/l (ppm fluoride in the drinking water and 85 children were selected from low fluoride area with 0.4mg/l (ppm fluoride in the drinking water. The intelligence quotient (IQ of each child was measured by the Raven's test. The history of illnesses affecting the nervous system, head trauma, birth weight (2.5kg or  2.5kg, residental history, age and sex of children were investigated by questionnaires completed by the children's parents. Data were analyzed by Chi-Square test with p<0.05 as the limit of significance. Results: In the high fluoride area the mean IQ of children (87.911 was significantly lower than in the low fluoride area (98.912.9 (P=0.025. Conclusion: Based on the findings of this study, exposure of children to high levels of fluoride may carry the risk of impaired development of intelligence.

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

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

    2016-09-01

    This study investigated the fluoride present in tea plants (Camellia sinensis (L.) O. Kuntze) and its relationship to soils, varieties, seasons and tea leaf maturity. The study also explored how different manufacturing processes affect the leaching of fluoride into tea beverages. The fluoride concentration in the tea leaves was significantly correlate to the concentration of water-soluble fluoride in the soil. Different tea varieties accumulated different levels of fluoride, with varieties, Anji baicha having the highest and Nongkang zao having the lowest fluoride concentration. In eight different varieties of tea plant harvested over three tea seasons, fluoride concentration were highest in the summer and lowest in the spring in china. The fluoride concentration in tea leaves was directly related to the maturity of the tea leaves at harvest. Importantly, the tea manufacturing process did not introduced fluoride contamination. The leaching of fluoride was 6.8% and 14.1% higher in black and white tea, respectively, than in fresh tea leaves. The manufacturing step most affecting the leaching of fluoride into tea beverage was withering used in white, black and oolong tea rather than rolling or fermentation. The exposure and associated health risks for fluoride concentration in infusions of 115 commercially available teas from Chinese tea markets was determined. The fluoride concentration ranged from 5.0 to 306.0mgkg(-1), with an average of 81.7mgkg(-1). The hazard quotient (HQ) of these teas indicated that there was no risk of fluorosis from drinking tea, based on statistical analysis by Monte Carlo simulation. PMID:27162130

  7. In vitro evaluation of fluoride products in the development of carious lesions in deciduous teeth

    Lucineide de Melo Santos

    2009-09-01

    Full Text Available The purpose of this study was to evaluate the effect of the application of fluoride products on the development of enamel caries in deciduous teeth. A total of 108 deciduous teeth were chosen for the study. Acid-resistant varnish was applied on the teeth, leaving only one area of 5 mm x 1 mm of dental enamel exposed. The teeth were allocated randomly to one of the following groups: 1 control - toothpaste without fluoride; 2 1.23% fluoride gel; 3 Duraflur fluoride varnish; 4 Duraphat fluoride varnish; 5 Fluorniz fluoride varnish; 6 Fluorphat fluoride varnish; 7 varnish with Duofluorid; 8 12% silver fluoride diamine (Cariestop; 9 children's fluoride toothpaste (500 ppm. The tested products were applied on the teeth according to the manufacturer's recommendations and the teeth were stored in a moist environment for 24 hours. Each group of teeth was then subjected to a pH cycling model for 14 days, after which the teeth were cut through the center for an analysis of the depth of the carious lesion by polarized light microscopy. Comparisons were made between the treatments and the control group. The mean lesion depth values were 318 μm ± 39 (control, 213 μm ± 27 (fluoride gel, 203 μm ± 34 (Duraflur, 133 μm ± 25 (Duraphat, 207 μm ± 27 (Fluor-niz, 212 μm ± 27 (Fluorphat, 210 ± 28 (Duofluorid, 146 ± 31 (Cariestop and 228 ± 24 (fluoride toothpaste. None of the products used here was able to completely prevent the formation of lesions. The highest cariostatic effect was achieved by fluoride varnish Duraphat and the lowest by the fluoride toothpaste.

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

    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

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

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

    2015-01-01

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

  10. A Comparison of Fluoride Uptake by Sound Enamel Following Application of Sodium Fluoride Mouthrinses and APF Gels Produced in Iran with Standardized Foreign Samples

    A Kowsari

    2002-02-01

    Full Text Available The goal of this investigation is to compare the extent of fluoride uptake by sound enamel following application of two commercial mouthrinses containing sodium fluoride (0.2% and a topical gel containing APF (1.23% produced in Iran with those of foreign standardized ones. Sixty extracted premolars were used. Each tooth was divided into two lingual and buccal halves, one half as control, the other one as experimental. Enamel biopsy technique (two- step acid etching was used to determine the concentration of fluoride and calcium in each sample. For data comparison and fluoride uptake estimation, the depths of layers with the use of linear regression analysis were standardized to 25 and 50um. The analysis showed that in Iranian mouthrinse no. 1, there is linear correlation between fluoride concentration and enamel depth, in both control and experimental group at the first and second layers, while, in other groups, this correlation was observed just at the first layer (superficial enamel layer. The greatest fluoride uptake was seen at Iranian mouthrinse no.2 and the least was seen at foreign mouthrinse no. 3. From among two APF gels, the greatest uptake was observed at gel no. 1 (Iranian. The results showed that all three Iranian products increase fluoride content of enamel, moreover the level of fluoride uptake, while applying Iranian products, in comparison with foreign ones, shows considerable increase.

  11. Effect of various rinsing protocols after use of amine fluoride/stannous fluoride toothpaste on the bacterial composition of dental plaque

    C. van Loveren; V.A.M. Gerardu; C.H. Sissons; M. van Bekkum; J.M. ten Cate

    2009-01-01

    This clinical study evaluated the effect of different oral hygiene protocols on the bacterial composition of dental plaque. After a 2-week period of using fluoride-free toothpaste, 30 participants followed three 1-week experimental protocols, each followed by 2-week fluoride-free washout periods in

  12. 高氟土壤的氟动力学吸附试验研究%Experiment on Fluoride Kinetics Adsorption of High Fluoride Soils

    段江飞; 刘浩; 时孟杰

    2014-01-01

    通过室内水土试验,研究山东高密高氟地区的土壤对氟的动力学吸附特性,并用典型的低氟土试验进行对比。从化学动力学的角度讨论高氟土壤对氟的吸附行为。高氟土壤对氟的吸附有其特殊性;高氟土壤对氟的吸附分为快、慢两个阶段;羟基是影响氟吸附的重要因素。%Through indoor soil test,the article is based on strudies fluorine kinetics adsorption of soils in high density flu-oride region of Shandong Province and comparing by low fluoride soil experiment.It discusses the way of Fluoride adsorp-tion by high fluoride soils from the point of chemical kinetics.The results show that fluoride adsorption by high fluoride soils has its particularity;the tendency of fluoride adsorption is faster at the first stage and slower at the second stage;Hydroxyl is one of the important factors to affect the fluoride adsorption.

  13. A composite modulated structure approach to the lanthanide oxide fluoride, uranium nitride fluoride and zirconium nitride fluoride solid-solution fields

    It is shown that the only generally applicable crystallographic approach to the anion excess, fluorite-related solid-solution fields reported in the zirconium nitride fluoride, uranium nitride fluoride and lanthanide oxide fluoride systems is a composite modulated structure approach. A TEM and powder XRD study has been made of the ZrNxF4-3x (0.906 Q ≅ 5.2, bQ ≅ 5.4, cQ ≅ 5.4 A, qQ -cQ* + [cH* - cQ*Q]) if the description used is based upon the Q sub-structure and B:Pmcm:s1 anti 1 {aH = aQ ≅ 5.2, bH 1/2bQ ≅ 2.7, cH=(p/q)cQ (pQ≅4.56 A, qH 1/2bH* + [cH* - cQ*]} if the description used is based upon the H sub-structure. The relationships between the reciprocal lattices of the component sub-structures are given by aH* = aQ*, bH* = 2bQ* and cH* ≅ 1.183cQ*. Fourier decomposition of the previously reported conventional superstructure refinement of one member of this solid-solution field, Zr108N98F138, has provided both underlying parent sub-structures as well as an approximation to the atomic modulation functions (AMF's) describing the mutual influence of the two parent sub-structures upon each other. In addition, such a Fourier decomposition has given an indication of the sorts of problems that will inevitably be encountered in accurately determining the appropriate AMF's when a conventional superstructure refinement of such composite modulated structures is attempted. (orig.)

  14. Mechanochemical-hydrothermal synthesis and characterization of fluoridated hydroxyapatite

    Fluoridated hydroxyapatite (FHAp) was successfully synthesized from the starting materials of CaCO3, CaHPO4.2H2O, and CaF2 via a mechanochemical-hydrothermal route. X-ray diffraction, infrared spectroscopy, surface area measurements, and scanning electron microscopy identified the resultant powders as FHAp nanocrystals with the specific surface areas of up to 114.72 m2/g. The mechanism study revealed that under such mechanochemical-hydrothermal conditions the formation reactions of FHAp were completed in two stages. The starting materials firstly reacted into a poorly crystallized calcium-deficient apatite and the complete incorporation of fluoride ions into apatite occurred in the second stage

  15. Observation of color center peaks in calcium fluoride

    Aoki, T. [LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704, USA (United States); Garvie, L.A.J. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Rez, P., E-mail: Peter.Rez@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)

    2015-06-15

    Alkali halides such as calcium fluoride all have color center defects that absorb light in the visible region. Using a moncochromator equipped, aberration corrected, scanning transmission electron microscope (STEM) we recorded spectra showing the time evolution of the generation of F and H centers in calcium fluoride. The final stage of electron beam irradiation is the formation of metallic calcium nanoparticles. High resolution low loss spectra for the Vacuum Ultraviolet region were also recorded. - Highlights: • Color center defects clearly identified by high resolution EELS of CaF{sub 2}. • Both F Centers and H Centers produced by electron beam irradiation. • Ultimately metallic calcium is left as evidenced by plasmon and density of states. • High resolution low loss (VUV) spectra also recorded.

  16. The dissolution of kaolin by acidic fluoride wastes

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

    1997-01-01

    The potential use of kaolin as a lining material for the storage of acidic and acidic fluoride wastes is investigated, No significant changes are observed gravimetrically or structurally for kaolin soaked under acidic conditions down to pH 2 for periods up to 90 days, Some release of aluminium was...... noted with decreasing pH, Severe kaolin dissolution was apparent, however, when soaked in solutions less than pH 3 to 4 with a fluoride concentration of 0.05 M. Aluminium-oxygen bonding in kaolin appears to be substantially more prone to hydrofluoric acid attack than does silicon-oxygen bonding......, resulting in a preferential release of aluminium over silicon into solution. The solution pH was found to decrease with the dissolution reaction as fluorosilicic acid was produced during the kaolin breakdown....

  17. Plant tissue hybrid electrode for determination of phosphate and fluoride

    Schubert, F.; Renneberg, R.; Scheller, F.W.; Kirstein, L.

    1984-08-01

    A biosensor for inorganic phosphate and fluoride has been developed by coupling a potato (Solanum tuberosum) tissue slice and immobilized glucose oxidase with a Clark oxygen electrode. Measurement is based on the inhibition by either ion of potato acid phosphates catalyzed glucose 6-phosphate hydrolysis. The precision is 1.7% and 6.5% and the lower detection limit 2.5 X 10/sup -5/ M and 1 X 10/sup -4/ M for phosphate and fluoride, respectively. For phosphate determination the hybrid sensor is stable for 28 days or 300 assays. With a higher limit of detection the sensor can be applied in a commercial enzyme electrode based device. Its application for phosphate determination in fertilizer and urine samples is described.

  18. Determination of boron, silica, fluoride, MBAS, phenols, cyanide and sulphide

    This study forms part of the NIWR's series of interlaboratory comparison studies involving southern African laboratories engaged in water and wastewater analysis, and is concerned with the analysis of synthetic water samples by 31 laboratories for boron, silica, fluoride, methylene blue active substances (MBAS), phenols, cyanide and sulphide. The results obtained are evaluated and discussed. Recognised standard methods, or modifications of these methods, were used for most of the determinations. Results from the boron, silica and fluoride determinations showed, in general, acceptable accuracy and precision. Results from the MBAS, phenols, cyanide and sulphide determinations were, however, somewhat widespread, and illustrated the difficulty in obtaining reliable results from the measurement of relatively low levels of these determinands

  19. Poly(vinylidene fluoride)/Clay Nanocomposites by Melt Compounding

    2008-01-01

    The crystalline structures, morphologies, and mechanical properties of poly(vinylidene fluoride)/clay nanocomposites were studied using X-ray diffraction(XRD), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR), polarized optical microscopy(POM), and tensile tests. The results of XRD and TEM show that organoclays are dispersed in the poly(vinylidene fluoride)(PVDF) matrix. A clay-induced crystal transformation from α-phase to β-phase of PVFD was confirmed by XRD and FTIR. Clay layers restricted the growth of spherulite. The tensile tests indicate that the tensile modulus and yield strength as well as the elongation at break decrease when clay is loaded.

  20. Perspectives in the effective use of fluoride in Asia

    Petersen, P E; Phantumvanit, P

    2012-01-01

    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......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...

  1. Fluoride glass starting materials - Characterization and effects of thermal treatment

    Chen, William; Dunn, Bruce; Shlichta, Paul; Neilson, George F.; Weinberg, Michael C.

    1987-01-01

    The production of heavy metal fluoride (HMF) glasses, and the effects of thermal treatments on the HMF glasses are investigated. ZrF4, BaF2, AlF3, LaF3, and NaF were utilized in the synthesis of zirconium-barium-lanthanum-aluminum-sodium fluoride glass. The purity of these starting materials, in particular ZrF4, is evaluated using XRD analysis. The data reveal that low temperature heating of ZrF4-H2O is effective in removing the water of hydration, but causes the production of ZrF4 and oxyfluorides; however, dehydration followed by sublimation results in the production of monoclinic ZrFe without water or oxyfluoride contaminants.

  2. Determination of fluoride in coal using pyrohydrolysis for analyte separation

    Dressler, V.L.; Pozebon, D.; Flores, E.L.M.; Paniz, J.N.G.; Flores, E.M.M. [Federal University of Santa Maria, Santa Maria (Brazil)

    2003-04-01

    A method for the determination of fluoride in coal using pyrohydrolysis for sample decomposition is proposed. An apparatus was constructed, and the influence of vanadium pentoxide (V{sub 2}O{sub 5}) as a catalyst for the pyrohydrolysis reaction was investigated. It was verified that V{sub 2}O{sub 5} does not influence the release of fluoride from coal. Certified and non-certified samples were analysed using an ion selective electrode (ISE) for analyte detection. Precise (RSD < 7%) and accurate ( recovery in accordance with certified values) results were obtained. The limit of quantification (LOQ) of the method was 5.0 {mu}gF/g of sample, using 20 mg of sample and a final dilution to 10 mL. The sample frequency was 5 samples h{sup -1}.

  3. Some metallic materials and fluoride salts for high temperature applications

    There has been a special Ni base alloy MONICR for high temperature applications in fluoride salt environments developed in the framework of the complex R and D program for the Molten Salt Reactor (MSR) - SPHINX (SPent Hot fuel Incinerator by Neutron fluX) concept development in the Czech Republic. Selected results of MONICR alloy tests and results of semi products fabrication from this alloy are discussed in the paper. The results of the structural materials tests are applied on semi-products and for the design of the testing devices as the autoclave in loop arrangement for high temperature fluoride salts applications. Material properties other Ni base alloys are compared to those of MONICR. Corrosion test results of the alloy A686 in the LiF - NaF - ZrF4 molten salt are provided and compared to the measured values of the polarizing resistance. (author)

  4. Trabecular stress fractures during fluoride therapy for osteoporosis

    Schnitzler, C.M.; Solomon, L.

    1985-10-01

    Joint pain and swelling in patients on fluoride therapy are generally attributed to rheumatic phenomena; however, their occurrence exclusively in the lower limbs suggests a mechanical cause. Eight patients receiving daily doses of sodium fluoride 1.09 mg/kg, elemental calcium 1 gm, and vitamin D 1000-2800 units for osteoporosis spontaneously developed 17 episodes of periarticular pain and swelling in the lower limbs. Radiographs taken within two weeks of the onset of pain were negative, but when repeated 4-6 weeks later showed features of healing stress fractures in the periarticular cancellous bone at the following sites: distal femur (2) proximal tibia (3), distal tibia (6), calcaneum (6). Bone scintigraphy was positive on five occasions, two before radiographic signs had appeared. (orig.).

  5. Radioluminescence of rare-earth doped potassium yttrium fluorides crystals

    The radioluminescence (RL) properties of K2YF5 crystals doped with Ce3+, Tb3+ and Dy3+ under ionizing irradiation excitation have been studied for the first time. The main objective of this work has been to assess the feasibility of using these crystals as detectors for fiberoptic radioluminescent dosimetry. In particular, it has been found that the RL intensity from both K2YF5:Tb (10%) and K2TbF5 is comparable to that from a commercial Al2O3:C crystal. Longer wavelength emission from these fluorides makes simple optical filtering technique possible to use in order to avoid the stem effect. Afterglow decay times for these fluorides have been found to be similar to that for Al2O3:C and, in particular, K2TbF5 does not show longer afterglow decay time compared to Al2O3:C.

  6. Observation of color center peaks in calcium fluoride

    Alkali halides such as calcium fluoride all have color center defects that absorb light in the visible region. Using a moncochromator equipped, aberration corrected, scanning transmission electron microscope (STEM) we recorded spectra showing the time evolution of the generation of F and H centers in calcium fluoride. The final stage of electron beam irradiation is the formation of metallic calcium nanoparticles. High resolution low loss spectra for the Vacuum Ultraviolet region were also recorded. - Highlights: • Color center defects clearly identified by high resolution EELS of CaF2. • Both F Centers and H Centers produced by electron beam irradiation. • Ultimately metallic calcium is left as evidenced by plasmon and density of states. • High resolution low loss (VUV) spectra also recorded

  7. Latest developments in non-fluoridated remineralizing technologies

    Goswami, M; Saha, S.; T R Chaitra

    2012-01-01

    The goal of modern dentistry is to manage non-cavitated carious lesions non-invasively through remineralization in an attempt to prevent disease progression, and to improve strength, esthetics, and function of teeth. The emphasis currently is being given to new technologies for enamel remineralization which suggest the changes in the understanding of dental caries. The aim of this paper is to review the contemporary non-fluoridated systems available for remineralization therapy and ideas for ...

  8. CONTRIBUTION OF MACROSCOPIC DIMENSION EFFECT TO PIEZOELFCTRICITY IN POLYVINYLIDENE FLUORIDE

    WEN Jianxun; TAKEO FURUKAWA

    1987-01-01

    In this paper, we have studied the piezoelectricity in the poled uniaxially drawn polyvinylidene fluoride. The piezoelectric constants d31, d32, da33 and Young's moduli 1/s11 and 1/s22 have been determined as a function of the remanent polarization Pr. The piezoelectric constants of the samples show a strong in-plane anisotropy. Such an anisotropy is mostly attributable to different Poisson's ratio. It is found that the piezoelectric activity mainly arises from macroscopic dimensional change.

  9. Vibrational Modes Analysis of Poly (Vinylidene Fluoride-Trifluoroethylene)

    李吉超; 王春雷; 钟维烈; 李正法

    2003-01-01

    The ground state geometry and vibrational modes of poly (vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]molecular chains have been investigated by ab initio molecular orbital calculation. The gauche bonds in P(VDFTrFE) are introduced by TrFE monomers. The vibrational modes are localized within all-trans segments. These results cause the infrared absorption weaker and diffused, and may be responsible for dielectric relaxation of the copolymers.

  10. Arsenic and fluoride in the groundwater of Mexico.

    Armienta, M A; Segovia, N

    2008-08-01

    Concentrations of arsenic and fluoride above Mexican drinking water standards have been detected in aquifers of various areas of Mexico. This contamination has been found to be mainly caused by natural sources. However, the specific processes releasing these toxic elements into groundwater have been determined in a few zones only. Many studies, focused on arsenic-related health effects, have been performed at Comarca Lagunera in northern México. High concentrations of fluoride in water were also found in this area. The origin of the arsenic there is still controversial. Groundwater in active mining areas has been polluted by both natural and anthropogenic sources. Arsenic-rich minerals contaminate the fractured limestone aquifer at Zimapán, Central México. Tailings and deposits smelter-rich fumes polluted the shallow granular aquifer. Arsenic contamination has also been reported in the San Antonio-El Triunfo mining zone, southern Baja California, and Santa María de la Paz, in San Luis Potosí state. Even in the absence of mining activities, hydrogeochemistry and statistical techniques showed that arsenopyrite oxidation may also contaminate water, as in the case of the Independencia aquifer in the Mexican Altiplano. High concentrations of arsenic have also been detected in geothermal areas like Los Azufres, Los Humeros, and Acoculco. Prevalence of dental fluorosis was revealed by epidemiological studies in Aguascalientes and San Luis Potosí states. Presence of fluoride in water results from dissolution of acid-volcanic rocks. In Mexico, groundwater supplies most drinking water. Current knowledge and the geology of Mexico indicate the need to include arsenic and fluoride determinations in groundwater on a routine basis, and to develop interdisciplinary studies to assess the contaminant's sources in all enriched areas. PMID:18335171

  11. Calculated energy response of lithium fluoride finger-tip dosimeters

    Calculations have been made of the energy response of the lithium fluoride thermoluminescent dosimeters being used at A.E.E. Winfrith for the measurement of radiation doses to the finger-tips of people handling radio-active materials. It is shown that the energy response is likely to be materially affected if the sachet in which the powder is held contains elements with atomic numbers much higher than 9 (e.g. if the sachet is made from polyvinyl chloride). (author)

  12. Amelioration of Fluoride Toxicity with the Use of Indigenous Inputs

    Maitra A; Datta J.K.; Mondal N.K.

    2013-01-01

    An assessment was undertaken to study the efficacy of bacterial consortia isolated from different sources viz. rhizosphere of rice plant, oil spill sites of a petrol pump and from the sludge of a pharmaceutical waste water drain against the impact of fluoride. The experiments were conducted with two crops. In this mung bean experiment Vigna radiata was selected as a test crop. The seeds were sown in the field with bacterial consortia, compost and reduced dose (25% less nitrogen than recommend...

  13. Radiation damage and photochromism in the alkaline earth fluorides

    Detailed mechanisms are proposed for the defect reactions occurring in irradiated alkaline earth fluorides. Both pure and doped crystals are considered. For the former, the models rationalise much of the experimental data, particularly the studies of Hayes and Lambourn. The discussion of doped crystals explains the origin of the pronounced effects of trivalent impurities. The mechanism of formation of photochromic centres is discussed and the observed temperature dependence of the stability of these defects is explained successfully. (author)

  14. Contribution to the study of ruthenium fluorides, oxyfluorides and oxides

    Studies on the dry processing of spent fuels reveal a poor ruthenium decontamination of plutonium. For a better understanding of this result a study of ruthenium fluorides, oxyfluorides and oxides is carried out here as follows: - bibliographical review; - thermochromatographic identification of the number and nature of compounds formed by fluorination of microquantities of ruthenium; - confirmation of the thermochromatographic results by two other analytical methods: thermogravimetry and infrared spectroscopy

  15. Physico-Mechanical Properties of New Electrospun Polyvinylidene Fluoride Nanocomposites

    Ramadan, Ahmed Abdelatty Issa

    2015-01-01

    This study aimed to prepare and characterize poly(vinylidene fluoride) (PVDF) nanofibres with the following additives: graphene oxide (GO), cellulose, and silver nanoparticles (Ag-NPs). Two types of solvents were used to prepare the virgin and composite materials: acetone and DMF, which lead to a porous surface of the nanofibres. Effect of combination of the additives and the effect of two salts (sodium chloride and tetraethyl ammonium chloride) was also considered. These nanofibres were prod...

  16. Galvanic corrosion between orthodontic wires and brackets in fluoride mouthwashes.

    Schiff, Nicolas; Boinet, Mickaël; Morgon, Laurent; Lissac, Michèle; Dalard, Francis; Grosgogeat, Brigitte

    2006-06-01

    The aim of this investigation was to determine the influence of fluoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution of Fusayama-Meyer artificial saliva and in two commercially available fluoride (250 ppm) mouthwashes, Elmex and Meridol. Corrosion resistance was assessed by inductively coupled plasma-atomic emission spectrometry (ICP-MS), analysis of released metal ions, and a scanning electron microscope (SEM) study of the metal surfaces after immersion of different wire-bracket pairs in the test solutions. The study was completed by an electrochemical analysis. Meridol mouthwash, which contains stannous fluoride, was the solution in which the NiTi wires coupled with the different brackets showed the highest corrosion risk, while in Elmex mouthwash, which contains sodium fluoride, the CuNiTi wires presented the highest corrosion risk. Such corrosion has two consequences: deterioration in mechanical performance of the wire-bracket system, which would negatively affect the final aesthetic result, and the risk of local allergic reactions caused by released Ni ions. The results suggest that mouthwashes should be prescribed according to the orthodontic materials used. A new type of mouthwash for use during orthodontic therapy could be an interesting development in this field. PMID:16428255

  17. Sodium Fluoride Inhibits MMP-2 and MMP-9

    Kato, M.T.; Bolanho, A.; Zarella, B.L.; Salo, T.; Tjäderhane, L.; Buzalaf, M.A.R.

    2014-01-01

    The importance of fluoride (F) in preventing dental caries by favorably interfering in the demineralization-remineralization processes is well-established, but its ability to inhibit matrix metalloproteinases (MMPs), which could also help to prevent dentin caries, has not been investigated. This study assessed the ability of F to inhibit salivary and purified human gelatinases MMPs-2 and -9. Saliva was collected from 10 healthy individuals. Pooled saliva was centrifuged, and supernatants were...

  18. Preparation of Polyvinylidene Fluoride (PVDF) Hollow Fiber Hemodialysis Membranes

    Qinglei Zhang; Xiaolong Lu; Lihua Zhao

    2014-01-01

    In this study, the polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS). The influences of PVDF membrane thickness and polyethylene glycol (PEG) content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum a...

  19. Tokyo dark matter search experiment with lithium fluoride bolometer

    An experiment to search for hypothetical neutralino dark matter using lithium fluoride bolometer array is underway. This bolometer array consists of eight pieces of 21 g LiF bolometers. Fluorine has large sensitivity for axially coupled neutralino compared with other nuclei. We report on the first results from the pilot run in a shallow depth site (15 m w.e.). From the measured energy spectra the exclusion limits for the cross section of the elastic neutralino scattering off protons are evaluated

  20. Plasma fluoride and bromide concentrations during occupational exposure to enflurane or halothane

    Carlsson, P.; Ekstrand, J.; Hallen, B.

    1985-10-01

    The plasma fluoride and bromide concentrations were studied in operating theatre personnel. When enflurane was used, the increase in plasma fluoride concentration could not be distinguished from normal individual variations, but the plasma bromide concentration increased significantly when halothane was used. Seven patients were exposed to enflurane in a concentration of 200 parts per million for 4 h. A significant increase in the plasma concentration of fluoride was observed. The peak concentrations of fluoride occurred during exposure and the increase lasted less than 12 h. The increase in fluoride concentration was larger at this trace concentration than reported after anesthetic concentrations. Cerebrospinal fluid (CSF) fluoride concentration was also studied; a smaller and delayed increase was found in CSF compared to plasma.

  1. Community-oriented administration of fluoride for the prevention of dental caries

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

    2012-01-01

    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......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...

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

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

    2008-01-01

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

  3. Fabrication and characterization of fluoridated hydroxyapatite nanopowders via mechanical alloying

    The aim of this work was preparation and characterization of fluoridated hydroxyapatite (FHA) nanopowders with different degrees of fluoridation via mechanical alloying (MA) method. FHA nanopowders with a chemical composition of Ca10(PO4)6OH2-xFx (where x values were selected equal to 0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized using a mixture of appropriate amounts of calcium hydroxide, phosphorous pentoxide, and calcium fluoride powders by 6 h of mechanical alloying at 300 rpm, using eight balls with a diameter of 20 mm, and the ball-to-powder weight ratio equal to 35:1. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and ICP-OES analysis techniques were utilized in order to evaluate phase composition, agglomerates size distribution, morphology and particle size, functional groups, and purity of synthesized FHA nanopowders. The FTIR result combined with the X-ray diffraction indicated that single phase of homogeneous FHA with the carbonate peaks in the FTIR spectrum could be prepared after 6 h MA. TEM photomicrograph revealed that obtained powder after 6 h of MA was composed of FHA nanoparticles (35-65 nm). The results of ICP-OES analysis illustrated that synthesized nanopowder could fulfill the requirement of ASTM F1185-88 to be used as a biomaterial.

  4. Corrosion resistant materials for fluorine and hydrogen fluoride

    Aluminum and Duralumin are resistant against fluorine and hydrogen fluoride up to 600 and 700 K, respectively. The resistance of nickel and its alloys, particularly monel, against fluorine and hydrogen fluoride is fairly good up to 900 and 800 K. During the attack of nickel-chromium alloys by fluorine between 1000 and 1300 K, it appears an inner fluorination similarly to the inner oxidation. The resistance of titanium in water-free liquid fluorine at lower temperatures with -1 is comparable to that of nickel and monel. However, the corrosion of titanium in gaseous fluorine amounts at 377 K only 0,0082 mm.a-1. In spite of their limited resistance against fluorine and hydrogen fluoride, very pure molybdenum and tungsten are employed as construction materials in the rocket technology because of their large strength at high temperatures if fluorine-hydrogen and fluorine-hydrazine flames are used. Lanthanum and calcium borides are only little attacked by fluorine hydrazine flames between 1400 and 1800 K; they are superior to all special grade alloys. The same is true in a lower temperature region (290-400 K) with fluorcarbon resins. Organic materials substitute in increasing extent metal alloys and non-metal inorganic materials. (orig.)

  5. Removal of fluoride from semiconductor wastewater by electrocoagulation-flotation.

    Hu, C Y; Lo, S L; Kuan, W H; Lee, Y D

    2005-03-01

    This work employs an anodic surfactant, sodium dodecyl sulfate (SDS), to improve the flotation performance of the electrocoagulation-flotation (ECF) process to treated fluoride containing semiconductor wastewater following calcium precipitation. The dissolved fluoride ions and CaF(2) particles in the wastewater after calcium precipitation were effectively removed in the ECF process simultaneously. The dosage of SDS required for ECF was much less than those for dispersed air flotation (DiAF) or dissolved air flotation (DAF) processes because the CaF(2) particles can be collected by hydro-fluoro-aluminum flocs in ECF. Thus, SDS only served as a frother to make the bubbles tiny and stable in the ECF defluoridation process. The interference of co-existing anions can be overcome by increasing the dosage of calcium ions and SDS. The optimum initial acidity for ECF is close to the initial fluoride concentration after calcium precipitation; the amount of SS removed dropped rapidly if the initial acidity exceeded the optimal value because the surface charge of the hydro-fluoro-aluminum particles increased. The initial acidity of the wastewater after calcium precipitation can be modified by changing the [Ca(OH)(2)]/[Ca(2+)](T) ratio and the appropriate ratio is approximately given by the acid dissociation constant of hydrofluoric acid and the initial pH of the wastewater before calcium precipitation. PMID:15743636

  6. Professionally applied topical fluoride: evidence-based clinical recommendations.

    2007-03-01

    With the dramatic increase in the amount of scientific information available about oral health, an evidence-based approach to oral health care and the practice of dentistry is necessary. There is a need to summarize, critique, and disseminate scientific evidence and to translate the evidence into a practical format that is used easily by dentists. The evidence-based clinical recommendations in this report were developed by an expert panel established by the American Dental Association Council on Scientific Affairs that evaluated the collective body of scientific evidence on the effectiveness of professionally applied topical fluoride for caries prevention. The recommendations are intended to assist dentists in clinical decision making. MEDLINE and the Cochrane Library were searched for systematic reviews and clinical studies of professionally applied topical fluoride-including gel, foam, and varnish-through October 2005. Panelists were selected on the basis of their expertise in the relevant subject matter. The recommendations are stratified by age groups and caries risk and indicate that periodic fluoride treatments should be considered for both children and adults who are at moderate or high risk of developing caries. Included in the clinical recommendations is a summary table that can be used as a chairside resource. The dentist, knowing the patient's health history and vulnerability to oral disease, is in the best position to make treatment decisions in the interest of each patient. These clinical recommendations must be balanced with the practitioner's professional expertise and the individual patient's preferences. PMID:17389574

  7. The influence of trace elements on fluoride uptake by teeth

    To investigate the effect of various trace elements on fluoride uptake by teeth, the concentrations of F and other trace elements have been simultaneously determined in different regions of the teeth from children of South Australia. Teeth cross sectioned along the median plane have been used in these investigations, and their inside enamel, dentine and amelodentinal junctions investigated separately for the trace elemental composition. Fluoride has been determined by observing the 6-7 MeV gammas for the 19F(p,αγ)16O reaction, C by activation through the 12C(3He,n)14O reaction, while other trace elements have been measured by the thick target PIXE technique. Linear correlation coefficients have been calculated between the F concentrations in teeth and those of other trace elements observed. Fluoride is found to correlate best with C, Cu and Pb, poorly with Fe, Sr, Ni and Ag, while with Br and Zn it has-ve coefficients. Student's t-test has been applied to the data to examine the significance of the variation of Fand other trace elements amongst different dental tissues from healthy and diseased teeth. (orig.)

  8. High Fluoride Concentration Toothpastes for Children and Adolescents.

    Pretty, Iain A

    2016-01-01

    The purpose of this review is to present the available evidence to support the use of dentifrices with high (>1,500 ppm) concentrations of fluoride to help in the prevention and treatment of caries in high-risk children and adolescents. Recent evidence from high-quality systematic reviews supports the dose-response relationship between caries prevention and fluoride levels, and there is good evidence from randomised clinical trials to support the use of high fluoride dentifrices. Such products are typically prescribed oral pharmaceuticals that require thorough risk assessment by the clinician and restricting use in those less than 6 years old to cases where the risk of severe morbidity caused by caries is greater than that of aesthetically objectionable fluorosis and which should mitigate the risk of fluorosis. Further research is required on the use of population- or community-based interventions using such products and currently, the evidence for dentifrices containing more than 2,900 ppm is weaker than for those containing 2,800 ppm or less. PMID:27101304

  9. Enriched fluoride sorption using alumina/chitosan composite

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

  10. Characterization and biocompatibility of fluoridated biphasic calcium phosphate ceramics

    Zhu, Z.L. [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Yu, H.Y. [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)], E-mail: yhyang6812@tfol.com; Zeng, Q. [Institute for Nanobiomedical Technology and Membrane Biology, Sichuan University, Chengdu 610041 (China); He, H.W. [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)

    2008-11-15

    Biphasic calcium phosphate ceramics (BCP) has been widely used in tooth and bone implants due to its excellent biocompatibility. Incorporation of fluorine ions in BCP has drawn much attention because of the beneficial role played by the fluorine ions in bone and tooth growth. The aim of this study was to obtain fluoridated biphasic calcium phosphate (FBCP) by immersing BCP into saturated ZnF{sub 2} solution with F{sup -} concentration of 3500 mg/l at different times. The phase and incorporation of fluoride into BCP were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The biomineralization and influence of FBCP on osteoblastic behavior were evaluated and compared with that of biphasic calcium phosphate (BCP). The results exhibited that the phase evolution of the BCP was affected by the fluoride incorporation and the FBCP significantly improved the differentiation and proliferation of osteoblasts. These findings suggest that the FBCP would be very useful as a bone reconstructive material.

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

    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

  12. Feasibility and costs of water fluoridation in remote Australian Aboriginal communities

    Ehsani Jonathon P

    2007-06-01

    Full Text Available Abstract Background Fluoridation of public water supplies remains the key potential strategy for prevention of dental caries. The water supplies of many remote Indigenous communities do not contain adequate levels of natural fluoride. The small and dispersed nature of communities presents challenges for the provision of fluoridation infrastructure and until recently smaller settlements were considered unfavourable for cost-effective water fluoridation. Technological advances in water treatment and fluoridation are resulting in new and more cost-effective water fluoridation options and recent cost analyses support water fluoridation for communities of less than 1,000 people. Methods Small scale fluoridation plants were installed in two remote Northern Territory communities in early 2004. Fluoride levels in community water supplies were expected to be monitored by local staff and by a remote electronic system. Site visits were undertaken by project investigators at commissioning and approximately two years later. Interviews were conducted with key informants and documentation pertaining to costs of the plants and operational reports were reviewed. Results The fluoridation plants were operational for about 80% of the trial period. A number of technical features that interfered with plant operation were identified and addressed though redesign. Management systems and the attitudes and capacity of operational staff also impacted on the effective functioning of the plants. Capital costs for the wider implementation of these plants in remote communities is estimated at about $US94,000 with recurrent annual costs of $US11,800 per unit. Conclusion Operational issues during the trial indicate the need for effective management systems, including policy and funding responsibility. Reliable manufacturers and suppliers of equipment should be identified and contractual agreements should provide for ongoing technical assistance. Water fluoridation units should

  13. Effects of Fluoride on the Interactions between Amelogenin and Apatite Crystals

    Tanimoto, K; Le, T; Zhu, L; Chen, J.; Featherstone, JDB; Li, W; Denbesten, P

    2008-01-01

    Fluorosed enamel is more porous and less mineralized, possibly related to altered amelogenin-modulated crystal growth. The purpose of this study was to examine the role of fluoride in interactions between amelogenin and apatite crystals. Recombinant human amelogenin (rhl74) was bound to carbonated hydroxyapatite containing various amounts of fluoride, and analyzed by protein assay, SDS PAGE, and AFM. Interactions between rh174 and fluoride were assayed by isothermal titration calorimetry (ITC...

  14. Obtaining and thermodynamic properties of cobalt fluoride tetrahydrate and cobalt hydroxycarbonate

    Present article is devoted to obtaining and thermodynamic properties of cobalt fluoride tetrahydrate and cobalt hydroxycarbonate. Therefore, the cobalt fluoride tetrahydrate (II) was obtained by the reaction of cobalt hydroxycarbonate(II) with hydrofluoric acid solutions of different concentrations. The enthalpy and adverse reactions was defined by means of calorimetry method. The enthalpy of formation of cobalt fluoride tetrahydrate (II) and cobalt hydroxycarbonate(II) was determined by thermochemical cycles.

  15. The role of fluoride in the preventive management of dentin hypersensitivity and root caries

    Petersson, Lars G.

    2012-01-01

    Objective The objectives were to bring light on fluoride to control dentin hypersensitivity (DHS) and prevent root caries. Materials and methods Search strategy included papers mainly published in PubMed, Medline from October 2000 to October 2011. Results Fluoride toothpaste shows a fair effect on sensitive teeth when combined with dentin fluid-obstructing agents such as different metal ions, potassium, and oxalates. Fluoride in solution, gel, and varnish give an instant and long-term relief ...

  16. Self-Reported Knowledge and Attitude of Dentists towards Prescription of Fluoride

    Yarahmadi, Zahra; Kharazifard, Mohammad Javad

    2015-01-01

    Objectives: This study aimed to assess the self-reported knowledge and attitude of dentists towards fluoride prescription. Materials and Methods: A questionnaire survey was conducted at the national annual dental congress in 2010 in Tehran-Iran. Dentists’ level of knowledge about the preventive effects of systemic and topical administration of fluoride was assessed as well as their attitudes towards its application. Self-reported practice for two paper patients (a child and an adult with high risk of dental caries) was assessed. Data were analyzed using SPSS, chi-square test and logistic regression. Results: A total of 347 dentists including 232 (73.4%) males and 84 (26.6%) females responded; 84.7% agreed/strongly agreed with addition of fluoride to water and 66% agreed with prescription of fluoride tablets/drops in fluoride-deficient areas. Fluoridated toothpastes were considered useful by 85.3%; this rate was 78.7% for fluoride rinse and 87.6% for fluoride varnish, foam or gel. The majority of dentists (67.4%) reported no access to clear guidelines on fluoride application; 83% considered fluoride to be effective for caries prevention in children less than 12 years and 39.2% believed it was useful for adults and adolescents; 50% of the respondents correctly managed the high-risk child and adult with respect to appropriate selection of fluoride product. Younger dentists (OR=0.94; 95% CI 0.8–0.9; P=0.043) and new graduates (OR=0.94; 95% CI 0.89–0.99; P=0.034) were more likely to correctly manage the high-risk child. Conclusion: Dentists had good knowledge and positive attitudes towards fluoride application. New graduates were more likely to correctly manage the young high-risk patient. PMID:27123013

  17. Fluorides for the prevention of early tooth decay (demineralised white lesions) during fixed brace treatment

    Benson, P.E.; Parkin, N.; Dyer, F.; Millett, D. T.; Furness, S.; P. Germain

    2013-01-01

    Demineralised white lesions (DWLs) can appear on teeth during fixed brace treatment because of early decay around the brackets that attach the braces to the teeth. Fluoride is effective in reducing decay in susceptible individuals in the general population. Individuals receiving orthodontic treatment may be prescribed various forms of fluoride treatment. This review compares the effects of various forms of fluoride used during orthodontic treatment on the development of DWLs. This is an updat...

  18. Fluoride Plus Functionalized β-TCP: A Promising Combination for Robust Remineralization

    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 ...

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

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

  20. Fluoride mapping during concentration of simulated high level radioactive liquid waste

    This paper provides brief account of the experimental studies performed to understand the behavior of fluoride ions during evaporation of simulated High Level Waste (HLW). The fluoride containing HLW will be generated during reprocessing of Thoria containing spent fuel. In order to finalize schematics and process flow sheets for management of such type of waste, it is important to understand behavior of fluoride at different stage of waste treatment including evaporation. (author)

  1. Combined influence of fluoride and biofilms on the biotribocorrosion behavior of titanium used for dental applications

    Cruz, H.; Henriques, Mariana; Teughels, Wim; Celis, Jean-Pierre; L. A. Rocha

    2015-01-01

    Dental implant failures occur mainly due to biofilm infections and mastication micro-movements or load stresses that may induce wear degradation. Dental implants microgaps are highly susceptible areas for biofilm formation and fluoride retention. Although fluoride is an antimicrobial agent widely used in caries prevention, its influence on biofilms under sliding wear remains unknown. The main aim of this work was to assess the effect of mixed biofilms and fluoride on the tribocorrosion behavi...

  2. A randomized clinical trial on arresting dentin caries in preschool children by topical fluorides

    Duangthip, Duangporn

    2015-01-01

    Introduction: Silver diammine fluoride (SDF) has been found to be effective in preventing and arresting dental caries in children. The annual or semi-annual application of SDF may not be practical in migratory populations or effective high caries risk patients. So far, no data are available about the effectiveness of intensive fluoride treatment in arresting dental caries in primary teeth. Objectives: This study aimed to compare the effectiveness of three topical fluoride application prot...

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

    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. PMID:26822219

  4. Fluoride removal from drinking water by adsorption using bone char as a biosorbent

    Ma, W; Ya, F.; Wang, R.; Zhao, Y. Q.

    2008-01-01

    As a biomass material, bone char was investigated for the feasibility to be used as a cost-effective biosorbent for fluoride removal from drinking water in groundwater environment. Based on the batch tests with natural tourmalin and active alumina being the reference adsorbents, BF (referring to bone char) has demonstrated a higher fluoride adsorption capacity. This capacity was found being increased with the increase of fluoride concentration. Furthermore, BF based column adsorption experime...

  5. Assessment of Available and Stable Fluoride in Four Widely-Used Toothpastes in the Iranian Market

    Jaber Yaghini; Sima Kiani; Shiva Mortazavi; Bahareh Haghshenas; Ahmad Mogharehabed

    2014-01-01

    Objective: Presence of available and stable fluoride in a dentifrice formulation is a major requirement for an anti-caries effect. Although the available fluoride concentration in Iranian dentifrices has been reported in previous studies, there is little information on its stability; which is dependent upon dentifrice formulation. This study was done to assess the fluoride ion concentration and stability in four widely used dentifrices in Iran. Materials and Methods: In this analytical study,...

  6. [Comparative in vitro evaluation of modern glass ionomer cements for adhesion strength and fluoride release].

    Zhitkov, M Yu; Rusanov, F S; Poyurovskaya, I Ya

    2016-01-01

    The study proved similar adhesion strength and fluoride release level in aqueous extracts of glass ionomer cements Cemion (VladMiVa, Russia), Glassin Rest (Omega-Dent, Russia), Cemfil 10 (StomaDent, Russia) and Fuji VIII (GC Corporation, Japan). Despite of close concentrations of fluoride in glasses, the rate of fluoride release in water from calcium and calcium-barium glasses is much higher than that of strontium glasses. PMID:27239999

  7. Electrochemistry of thorium fluoride in LiCl-KCl eutectic melts and methodology for speciation studies with fluorides ions

    This paper reports the electrochemical behavior of ThF4 in LiCl-KCl molten salt. It proposes a potentiometric method to determine the complexation constants of thorium (IV) with fluorides. The knowledge of these constants leads to calculate the speciation diagram of Th(IV) species as a function of the concentration of fluoride ions in the salt. These results were extrapolate to give an estimation of the activity coefficient of ThF4 in the molten salt LiF-ThF4 (77.5-22.5 mol%). This salt is retained for the molten salt fast reactor system, currently studied as a Generation IV concept in the domain of nuclear energy

  8. Fluor determination by alkaline hydrolysis of the uranium and thorium fluorides

    The alkaline hydrolysis of the uranium and thorium fluorides is studded and a new method for the determination of the fluoride, on the basis of a indirect volumetric titration with standard soda, is proposed. The compounds that may influence the hydrolysis of the uranium fluoride and that may be occasionally found in it as impurities are also studied. the method can be applied to the uranium fluoride except when there is a great quantity of F2UO2 or UO3 present in the sample. (Author) 20 refs

  9. Effect of High Water Fluoride Concentration on the Intellectual Development of Children in Makoo/Iran

    Shadfar, M.; B Seraj; M Shahrabi; Ahmadi, R.; M Fallahzadeh; H. Farrokh Eslamlu; M. J. Kharazifard

    2012-01-01

    Objective: Prolonged excessive intake of fluoride during child’s growth and development stages has been associated with mental and physical problems. The aim of this study was to investigate the effect of excessive fluoride intake on the intelligence quotient (IQ) of children living in five rural areas in Makoo/Iran. Materials and Methods: In this cross-sectional study, 293 children aged 6–11 years were selected from five villages in Makoo with normal fluoride (0.8±0.3 ppm), medium fluoride (...

  10. Fluoride level in drinking water resources of gorgan rural regions, 1385

    H Rahimzadeh

    2007-01-01

    Full Text Available Background and Objectives: Fluoride is one of the anions existed in water and soil. Its amount is not the same in different kind of water. Since the most of body's need to fluoride should be provided by drinking water, this study was aimed at determining the fluoride level in water supply of Gorgan rural regions. Materials and Methods: In this Cross-Sectional study, the subjects were all 67 water sources of the region. Every season, a one litter Sample was taken in a plastic Container and tested by SPADS Method. After Collecting and encoding the data, ANOVA was used to analyze. Results: The Findings shows that there are 4 springs and 63 wells which are Located in the mountainous (N=16 and flat (N= 47 regions. In every season, the average fluoride Level was lower than Standard Level (1.5 mg/L. The difference between fluoride Level of wells (0.39±0.15mg/L and springs (0.16± 0.13mg/L is Significant (p<0.05 the fluoride Level of mountainous wells is higher than wells located in flat regions (0.13mg/L. This deference was Significant (p<0.05. Conclusion: Based on The results revealing the fluoride Level of drinking water in Gorgan Rural region is less than international Standard, we recommend adding of Supplementary fluoride in foodstuffs of The people Living in This region. Key words: fluoride, drinking water resources, Gorgan, spring

  11. Development of an empirical model for fluoride removal from photovoltaic wastewater by electrocoagulation process

    Drouiche, Nadjib

    2011-05-01

    Electrocoagulation experiments were conducted with bipolar aluminium electrodes to determine the optimum conditions for the fluoride removal from synthetic photovoltaic wastewater. A high fluoride concentration in community water supplies can cause fluorosis which has a detrimental effect on human health in particular on teeth and bones. A full 23 factorial design of experiments was used to obtain the best conditions of fluoride removal from water solutions. The three factors considered were initial fluoride concentration, applied potential, and supporting electrolyte dosage. Two levels for each factor were used; supporting electrolyte (0 and 100), applied potential (10 and 30 V), and initial fluoride concentration (20 and 25 mg/L). Results showed that the optimum conditions for fluoride removal from photovoltaic wastewater containing an initial fluoride concentration of 20 mg/L were a supporting electrolyte dose of 100 mg/L and an applied potential of 30 V. These gave a residual fluoride concentration of 8.6 mg/L which was below the standard discharge limit. A mathematical equation showing the relation between residual fluoride concentration and the effective variables was also developed. © 2011 Desalination Publications. All rights reserved.

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

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

    2012-01-01

    Currently, there are no studies in the literature evaluating salivary fluoride retention after small amounts of fluoride gel are applied to children's teeth. Therefore, the objective of the present study was to compare salivary retention after gel application using a toothbrush or by traditional application with trays. In this crossover study, children with active caries (n = 10) were randomized into one of the following treatment groups: a) application of fluoride gel using a tray (control), or b) application of fluoride gel with a toothbrush (treatment). After a 7-day washout period, the treatments were inverted. Unstimulated saliva samples were collected at baseline and 0.5, 5, 15, 30, 60 and 120 minutes after acidulated phosphate fluoride (APF) gel application in order to analyze fluoride retention in saliva. The area under the curve (AUC) was also calculated. There were no differences in fluoride retention after application of small amounts of APF with a toothbrush compared to traditional gel application using trays at all time points studied, and no differences in AUC were observed (Student t-test, p > 0.05). These results suggest that application of fluoride gel in children using a toothbrush can be utilized as an option rather than traditional trays, since the same salivary retention of fluoride is obtained using a lower dose. PMID:23184162

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

    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. PMID:26278188

  14. Effect of fluoride on growth and acid production by Streptococcus mutans in dental plaque.

    Van der Hoeven, J S; Franken, H C

    1984-01-01

    The aim of this study was to measure the effect of fluoride on the production of organic acids by Streptococcus mutans in dental plaque. The effect was studied in a simplified model of dental plaque with gnotobiotic rats monoinfected with S. mutans Ny341. Adaptation of S. mutans to fluoride was induced by feeding one group of the rats on fluoride-containing diet and drinking water. No difference was found in the accumulation of S. mutans on the teeth between the fluoride-adapted and the contr...

  15. The effect of fluoride on the cellular uptake and pool of amino acids

    Fluoride decreased the initial uptake of 2-aminoisobutyric acid (AIB) in LS cells only in high (supralethal) concentrations and after several hours of exposure. The steady state level of AIB seemed somewhat more sensitive as it was halved after 23 hours exposure to 6mM-NaF. The cellular levels of some natural amino acids were also reduced by fluoride. However, cells resistant to fluoride showed equally lowered levels of amino acids, indicating that the observed effect of fluoride on cellular amino acid levels may be of little importance. (author)

  16. In vitro evaluation of fluoride products in the development of carious lesions in deciduous teeth

    Lucineide de Melo Santos; José Ivo Limeira dos Reis; Maria Perolina de Medeiros; Sheyla Moreira Ramos; Juliane Mendes de Araújo

    2009-01-01

    The purpose of this study was to evaluate the effect of the application of fluoride products on the development of enamel caries in deciduous teeth. A total of 108 deciduous teeth were chosen for the study. Acid-resistant varnish was applied on the teeth, leaving only one area of 5 mm x 1 mm of dental enamel exposed. The teeth were allocated randomly to one of the following groups: 1) control - toothpaste without fluoride; 2) 1.23% fluoride gel; 3) Duraflur fluoride varnish; 4) Duraphat fluor...

  17. Effects of Fluoride on Lipid Peroxidation, DNA Damage and Apoptosis in Human Embryo Hepatocytes

    AI-GUO WANG; TAO XIA; QI-LONG CHU; MING ZHANG; FANG LIU; XUE-MIN CHEN; KE-DI YANG

    2004-01-01

    Objective To investigate the effects of fluoride on lipid peroxidation, DNA damage and apoptosis in human embryo hepatocyte L-02 cells. Methods Lipid peroxide (LPO) level, reduced glutathione (GSH) content, DNA damage, apoptosis, and cell cycle analysis were measured after in vitro cultured L-02 cells were exposed to sodium fluoride at different doses (40 μg/mL, 80 μg/mL, and 160 μg/mL) for 24 hours. Results Fluoride caused an increase of LPO levels and a decrease of GSH content in L-02 cells. There appeared to be an obvious dose-effect relationship between the fluoride concentration and the observed changes. Fluoride also caused DNA damage and apoptosis and increased the cell number in S phase of cell cycle in the cells tested. There was a statistically significant difference in DNA damage and apoptosis when comparing the high dose of fluoride treated cells with the low dose of fluoride treated cells. Conclusion Fluoride can cause lipid peroxidation, DNA damage, and apoptosis in the L-02 cell experimental model and there is a significant positive correlation between fluoride concentration and these pathological changes.

  18. Caries-­preventive Effect of 1300ppm Fluoride and Carrageenan Containing Toothpaste

    Anton Rahardjo

    2013-07-01

    Full Text Available 72 1024x768 Various studies stated that the increase concentration of fluoride in toothpastes leads to the reduction of calcium loss in enamel. Objective: The purpose of this study was to test the difference between the effect of 1300ppm fluoride with carrageenan toothpaste and 1000ppm fluoride only toothpaste on roughness and hardness of enamel surface. Methods: Enamel specimens were obtained from 30 extracted human premolars. The enamel specimens were randomly assigned to one of the three groups, 1300ppm fluoride with carrageenan toothpaste, 1000ppm fluoride only toothpaste and toothpaste with no fluoride as a negative control. The samples were immersed in 1% citric acid with pH 4 for 150 seconds for demineralization, afterwards exposed to each toothpaste for 6 minutes. Results: The results demonstrated that toothpaste with 1300ppm fluoride with carregeenan has two times greater efficacy in triggering remineralization than toothpaste with 1000ppm fluoride only, with regards to surface roughness and hardness recovery in an in vitro caries model. Conclusion: The results suggested that treatment of enamel with toothpaste containing 1300ppm fluoride with carrageenan has high potential in inducing remineralization on enamel.DOI: 10.14693/jdi.v20i1.125

  19. Reducing Exposure to High Fluoride Drinking Water in Estonia—A Countrywide Study

    Ene Indermitte

    2014-03-01

    Full Text Available Fluoride is a naturally occurring contaminant in groundwater in Estonia. There are several regions in Estonia with fluoride contents in public water supplies as high as 7 mg/L. Long-term exposure to high-fluoride drinking water may have several adverse health effects, primarily dental fluorosis. The opportunities for exposure reduction rely highly on water treatment technologies. Since 2004 public water suppliers in Estonia have made efforts to diminish fluoride content in drinking water systems. A follow-up study on a country level was carried out in 2004–2012 to analyze the changes in population exposure to excessive (over 1.5 mg/L fluoride in drinking water and to get information about the reduction methods applied by public water supplies (PWS to optimize the fluoride levels in public water system. The results showed that bigger PWS have been more effective in fluoride reduction measures than small PWS. The main methods used to lower the fluoride content were reverse osmosis technology and replacement of water sources with new ones (new drilled wells. As a result of all the measures taken the overall high-fluoride exposure has been reduced substantially (82%.

  20. Study of Nd-Co alloy production by means of fluoride technique

    Fluoride method of neodymium-cobalt alloy preparation consisting in fluorination of cobalt-containing raw materials and calcium-thermal reduction of neodymium and cobalt fluorides mixture has been proposed, theoretically substantiated and studied. Results of thermodynamic, kinetic and phase studies of cobalt and neodymium oxides fluorination, as well as of joint reduction of neodymium and cobalt fluorides, are presented. Flowsheets of the facilities for producing the above-mentioned fluorides and alloys are described. Potentiality of producing Nd-Co alloy with a higher neodymium content (up to 85% compared with Nd-Fe alloy) and ingot yield of 93-95% is shown

  1. Determination of Fluoride and Some Metal Ion Levels in the Drinking Waters in Kayseri Province

    TOKALIOĞLU, Şerife; ŞAHİN, Uğur; Kartal, Şenol

    2001-01-01

    Fluorine is one of the most common elements in the Earth's crust. Fluoride is recognized to be the most effective caries-preventive agent. The main sources of fluoride for people are generally food and drinking water. For this reason, the fluoride and also the metal ion (Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn) concentrations in the drinking waters collected from the city center of Kayseri and its counties were investigated. In the determination of fluoride and of Na and ...

  2. Thermodynamics of the conversion of calcium and magnesium fluorides to the parent metal oxides and hydrogen fluoride

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

    1997-02-01

    The authors have used thermodynamic modeling to examine the reaction of calcium fluoride (CaF{sub 2}) and magnesium fluoride (MgF{sub 2}) with water (H{sub 2}O) at elevated temperatures. The calculated, equilibrium composition corresponds to the global free-energy minimum for the system. Optimum, predicted reaction temperatures and reactant mole ratios are reported for the recovery of hydrogen fluoride (HF), a valuable industrial feedstock. Complete conversion of MgF{sub 2} is found at 1,000 C and a ratio of 40 moles of H{sub 2}O per 1 mole of MgF{sub 2}. For CaF{sub 2}, temperatures as high as 1,400 C are required for complete conversion at a corresponding mole ratio of 40 moles of H{sub 2}O per 1 mole of CaF{sub 2}. The authors discuss the presence of minor chemical constituents as well as the stability of various potential container materials for the pyrohydrolysis reactions at elevated temperatures. CaF{sub 2} and MgF{sub 2} slags are available as wastes at former uranium production facilities within the Department of Energy Complex and other facilities regulated by the Nuclear Regulatory Commission. Recovery of HF from these wastes is an example of environmental remediation at such facilities.

  3. Screening biological traits and fluoride contents of native vegetations in arid environments to select efficiently fluoride-tolerant native plant species for in-situ phytoremediation.

    Boukhris, Asma; Laffont-Schwob, Isabelle; Mezghani, Imed; El Kadri, Lefi; Prudent, Pascale; Pricop, Anca; Tatoni, Thierry; Chaieb, Mohamed

    2015-01-01

    High fluoride pollution has been detected in the surrounding soils of the coastal superphosphate industries in the Gulf of Gabes (Southeast of Tunisia). A study was conducted in vicinity of factories analysing plant functional traits combined with plant fluoride accumulation and soil metal concentrations aiming to screen more efficiently native plant species tolerant to this pollution. Aerial parts of 18 plant species out of the 10 most abundant species per site were harvested on two polluted sites of Gabes and Skhira at the vicinity of the factories and on the less polluted site of Smara. Native plant species accumulated fluoride following the gradient of soil pollution. Fluoride contents of plant aerial parts ranged from 37 mg kg(-1) to 360 mg kg(-1) and five plant species were only found in the most polluted site. However these latter had low biomass and soil cover. Crossing biological traits and fluoride contents, a selection grid for potentially restorative plant species enabled the selection of three native perennials i.e. Rhanterium suaveolens, Atractylis serratuloides and, Erodium glaucophyllum as potential candidates for an in-situ phytoremediation program on arid fluoride-polluted sites. This approach may be used in other fluoride-polluted Mediterranean environments. PMID:25014764

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

    Itai, K

    1991-02-01

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

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

    Elias Nahum Salmerón-Valdés

    2016-01-01

    Full Text Available Context: The fluoride release of sealants in vitro shows a marked decrease. Giomers are distinguishable from manufactured resin-based sealants and contain prereacted glass-ionomer particles (PRG. Aims: To compare the amounts of fluoride released from the main pit and fissure of a resin-based sealant with that from a Giomer and to assess the abilities of the sealant and the Giomer to recharge when exposed to regular use of fluoride rinse. Materials and Methods: The readings for the fluoride concentration were carried out for 60 days using a fluoride ion-specific electrode. After this period, the samples were recharged using a fluoride mouth rinse. The amount of fluoride released after this recharge was determined for 5 days. The data were analyzed using Student′s t- and analysis of variance tests. Results: In general, all materials presented higher fluoride release in the first 24 h; G1 and G4 showed a higher fluoride release in this period. On the other hand, G3 and G1 presented the most constant fluoride release until the 8 th day, wherein all the sealants considerably decreased in the amount of fluoride released. Conclusion: G1 and G3 released higher concentrations of fluoride, although no significant differences were found. Giomers recharged in the first 24 h after polymerization presented an improved and sustained fluoride release.

  6. Histopathological Effects of Varied Fluoride Concentration on Cerebrum in Albino Rats

    Sajad Hamid

    2012-02-01

    Full Text Available Fluorides have been a cause of concern for scientists and environmentalists for the long because of their harmful effects on the human and animal life but the problem was highlighted during the twentieth century because of great increase in the human population and industrialization. Since fluorides accumulate in calcified and hard tissues of the body such as bone and teeth and can be detected easily in these tissues, so most of the previous studies focused on the effects of fluorides on these tissues. However, during the past decade researchers all over the world have felt that there is a need to study the effects of fluorides on various other tissues of the body including CNS as fluoride intake for prolonged period is known to cause abnormal behavioural pattern, grave implications for Alzheimer’s Disease, Dementia, Attention deficit disorder and reduced I.Q in children as the fluorides are known to cross blood brain barrier. Hence the present study has thrown light on the involvement of brain in chronic fluoride toxicity. The target organ of studied was cerebrum. In the Study, albino rats were exposed to 30 or 100 ppm fluoride (asNaF in drinking water for 3 months. Rats exposed to 30 ppm fluoride did not show any notable alterations in brain histology, whereas rats exposed to 100 ppm fluoride showed significant neurodegenerative changes in lhe motor cortex.Changes included decrease in size and number of neurons in all the regions, signs of chromatolysis and gliosis in the motor cortex. These histological changes suggest a toxic effect of high-fluoride intake & on chronic use. [J Interdiscipl Histopathol 2012; 1(1.000: 30-34

  7. A role for PERK in the mechanism underlying fluoride-induced bone turnover

    While it has been well-documented that excessive fluoride exposure caused the skeletal disease and osteoblasts played a critical role in the advanced skeletal fluorosis, the underlying mechanism that mediated these effects remain poorly understood. The present study was undertaken to examine the effect of fluoride on bone of rats and MC3T3-E1 cells in vitro. Herein we found pathological features of high bone turnover in fluoride-treated rats, which was supported by an increase of osteogenic and osteoclastogenic genes expression in different stages of fluoride exposure. The skeletal toxicity of fluoride was accompanied by activation of endoplasmic reticulum (ER) stress and subsequent unfolded protein response (UPR). A novel finding of this study was that expression of PKR-like endoplasmic reticulum kinase (PERK) was the same trend with receptor activator for nuclear factor-κ B ligand (RANKL), and NF-E2 p45-related factor 2 (Nrf2) was the same trend with Runt-related transcription factor 2 (Runx2) in bones of rats exposed to varied fluoride condition. Based on these data, we hypothesized that up-regulation of PERK probably played a role in mediating bone turnover induced by fluoride. Action of fluoride on MC3T3-E1 cells differentiation was demonstrated through analysis of alkaline phosphatase (ALP) activity and mineralized nodules formation. Meantime, an increase of binding immunoglobulin protein (BiP) expression indicated the active ER stress in cells exposed to various dose of fluoride. Blocking PERK expression using siRNA showed the obvious decrease of osteogenic and osteoclastogenic factors expression in MC3T3-E1 cells exposed to certain dose of fluoride that could positively stimulate osteoblastic viability. In conclusion these findings underscore the importance of PERK in modulating fluoride induced bone formation and bone resorption. Understanding the link between PERK and bone turnover could probe into the mechanism underlying different bone lesion of

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

    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. PMID:25749926

  9. Effects of fluoride in drinking water on health of deciduous teeth

    Blagojević Duška

    2004-01-01

    Full Text Available INTRODUCTION High incidence of decayed deciduous teeth, as well as lack of adequate therapy, makes tooth decay prevention very important. One of the simplest ways to reduce tooth decay is fluoridation of drinking water. The optimal concentration of fluoride in drinking water is 1 ppm/l, and many waters naturally contain this quantity. Waters in Vojvodina are mainly poor in fluoride, except in a few regions. It has long been postulated that fluoride has a prophyilactic effect during intrauterine life. Today a theory of greater local impact of fluoride as well as its role in de- and remineralization of solid tooth tissue. Material and methods This epidemiologocal study was performed in the area of Vojvodina, in places with various fluoride concentrations in drinking water (0.18 - 1.04 ppm/l. Dental examination was performed among 145 children, 6 years of age. For tooth decay detection dmf index was used. Results and discussion In places with low and optimal fluoride concentration in drinking water the percentage of children with decayed teeth is different, but without statistical significance. The percentage of affected deciduous teeth is high in all places. In places with low fluoride concentration it is 24.2 - 32.3%, in places with optimal concentration is 27 - 32%. Everidge value DMF in all places is between 4.7 - 6.4. These results show that optimal fluoride concentration in drinking water decreases the incidence of tooth decay, but this difference is not significant. CONCLUSION Presence of fluoride in drinking water doesn't affect health of deciduous teeth. Decreased incidence of decayed deciduous teeth can be achieved only with combined usage of fluoride (local and systemic, as well as with an intensive health education program.

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

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

    2014-09-01

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

  11. The Univali Dental students’ knowledge level about the prophylactic and therapeutic use of fluoride

    Cláudia GAZONI

    2010-06-01

    Full Text Available Introduction: The knowledge about fluoridated products enables the perception of conditions that make fluoride a toxic or beneficial element. Objective: To verify the knowledge about the prophylactic and therapeutic use of fluoride among students in the 7th, 8th and 9th semester of the Dentistry Course at the Vale do Itajaí University (Univali in the first semester of 2008. Material and methods: It was a transversal descriptive study that gathered primary data through a semi-structured questionnaire, approaching the students’ knowledge about the fluoride application methods, the recommendations and the fluoride concentrations of products used in the clinical routine, as well as the fluoride levels to which the patients are already exposed to.Results:82.75% of the interviewed students know the acute probable toxic dose (PTD and 43.68% of them know the chronic toxic dose Dental fluorosis was mentioned as a chronic clinica manifestation by 71.26% of the students.Professional topical fluoride application(PTFA is used by 90.80% of the students and 85.05% of them recognize that the amount of fluoride toothpaste used in brushing is a relevant factor for chronic intoxication. None student was aware of the fluoride concentration used in Itajaí community water supply, and 77.01% of the students comprehend that the main mode of action of fluoride is topical and primary.Conclusion:Despite the large amount of information about fluoride received by students during the curricular program,most of them do not know how to use it in their clinical practice and are not aware of toxicity, concentrations,indications and correct uses for each patient.

  12. Fluorides of five- and six-valence transuranium elements

    NpF6, PuF6 and AmF6 are the heaviest known hexafluorides. They are molecular compounds like the much better known UF6. Due to the high volatility they have been of special technological interest with respect to dry methods for the reprocessing of spent nuclear fuel. Material problems avoided the technological introduction of such processes, however. The transuranium hexafluorides are very reactive substances, they fit the following series of reactivity WF6 6 6 6 6 6 and OsF6 6 6. Controlled hydrolysis first yields the only recently discovered oxidetetrafluorides NpOF4 and PuOF4 wich is followed by the fomation of the dioxiddifluorides MeO2F2 - a class of compounds which is also known for Am, for which element no binary hexafluoride could be prepared. NpF5, the only transuranium pentafluoride, is obtained by reacting NpF6 with PF3 in liquid HE or as an intermediate by oxidizing NpF4 with KrF2 in HF. The reaction of PuF6 with PF3 in HF only yields PuF4. No ternary fluorides of hexavalent transuranium elements are known, but a few polynary oxidfluorides like KPuO2F3 have been characterized poorly. CsMe(V)F6, Rb2Me(V)F7 and Me3NpF8 (Me(I) = Na, RB) are the only ternary fluorides with pentavalent transuranium elements. It must be stated that there is only little knowledge on fluorides of hexa- and penta-valent transuranium elements what offers a broad area for new investigations - despite the experimental difficulties in handling these extremely reactive compounds of the high-radioactive elements. 43 refs., 5 figs., 6 tabs

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

    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.

  14. Behaviour of metals and alloys in molten fluoride media

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

  15. Fluoride inhibits the antimicrobial peroxidase systems in human whole saliva.

    Hannuksela, S; Tenovuo, J; Roger, V; Lenander-Lumikari, M; Ekstrand, J

    1994-01-01

    Fluoride (F-) ions at concentrations present in vivo at the plaque/enamel interface (0.05-10 mM) inhibited the activities of lactoperoxidase (LP), myeloperoxidase (MP) and total salivary peroxidase (TSP) in a pH- and dose-dependent way. The inhibition was observed only at pH or = 0.1 mM. At pH 5.5 LP activity was inhibited by 85% and MP by 34% with 10 mM F-. TSP activity was also inhibited only at low pH (5.5) by approximately 25%. Furthermore, the generation of the actual antimicrobial agent in vivo, hypothiocyanite (HOSCN/OSCN-), of the oral peroxidase systems was inhibited by F-, again at low pH (5.0-5.5) both in buffer (by 45%) and in saliva (by 15%). This inhibition was observed only with the highest F- concentrations studied (5-10 mM). Fluoridated toothpaste (with 0.10 or 0.14% F) mixed with saliva did not inhibit TSP or HOSCN/OSCN- generation. This may have been due to the 'buffering' effect of toothpaste which did not allow salivary pH to drop below 5.9. We conclude that the F- ions in acidic fluoride products, e.g. in gels or varnishes (but not in toothpastes), may have the potential to locally inhibit the generation of a nonimmune host defense factor, HOSCN/OSCN/SCN-, produced by oral peroxidase systems. The possible clinical significance of this finding remains to be shown. PMID:7850846

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

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

    2009-11-15

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

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

    Heslin, T.

    1974-01-01

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

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

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

    2015-07-01

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

  19. Impact and remedial strategy of Fluoride in Ground Water – A Review

    Bhagwan yadav

    2014-02-01

    Full Text Available According to WHO report 20% of the fluoride-affected villages in the whole world are in India, viz 33,231 villages are affected by fluoride in the country. Drinking water with excessive concentration of fluoride causes fluorosis which progresses gradually and becomes a crippling malady in the long run. It affects people of all age group, rich, rural, and urban population. It has attained a very alarming dimension. Rajasthan suffers both the problems of quantity and quality of water. In most part of the state groundwater is either saline or having high nitrates and fluoride content. Obviously, groundwater is the major source of drinking water and over 94% of the drinking water demand is met by groundwater. Fluoride concentrations beyond the standards cause dental and skeletal fluorosis. Fluoride toxicity can also cause non-skeletal diseases like aches and pain in the joints, non-ulcer dyspepsia, Polyurea and polydipsia, muscle weakness, fatigue, anemia with very low hemoglobin levels, etc besides other reasons. Many researchers have used various types of inexpensive and effective adsorption medium like clays, solid industrial wastes such as red mud, spent bleaching earths, spent catalysts and fly ash, activated alumina, carbonaceous materials, bone charcoal, natural and synthetic zeolites, etc. for the treatment of fluoride contamination. This paper presents a review, which focuses on the sources of fluoride in ground water, its impacts on health and different control measures.

  20. THE EFFECT OF FLUORIDE ON THE EFFECTIVENESS OF CONVENTIONAL COAGULATION/FLOCCULATION/SEDIMENTATION USING ALUMINUM SULFATE

    The Safe Drinking Water Act states that no drinking water facility is reuqired to fluoridate their water, however, any facility fluoridating their water is bound by the Maximum contaminant Level (MCL) of 4 mg/L. A survey of 600 large water utilities was conducted in conjunction w...

  1. Preventing Tooth Decay: A Guide for Implementing Self-Applied Fluoride in Schools.

    National Inst. of Dental Research (NIH), Bethesda, MD.

    This guidebook was developed to assist citizens in initiating programs to prevent tooth decay in young children through the use of fluoridation. It contains outlines for determining the needs of the school and community for fluoride in drinking water, and presents the various steps and activities that are necessary for developing and implementing…

  2. Fluoride-driven 'turn on' ESPT in the binding with a novel benzimidazole-based sensor.

    Liu, Kai; Zhao, Xiaojun; Liu, Qingxiang; Huo, Jianzhong; Zhu, Bolin; Diao, Shihua

    2015-01-01

    A novel fluorescence sensor (BIP) bearing NH and OH subunits displayed a highly selective and sensitive recognition property for fluoride over other anions. Fluoride-driven ESPT, poorly used in anion recognition and sensing, was suggested to be responsible for the fluorescence enhancement with a blue shift of 35 nm in the emission spectrum. PMID:25977729

  3. Some special features of the caries preventive effect of water-fluoridation

    Backer Dirks, O.; Houwink, B.; Kwant, G.W.

    1961-01-01

    In March 1953 water-fluoridation was started in Tiel, the Netherlands. From the caries numbers of three age classes the differences in caries inhibition for the various teeth and for the various tooth surfaces are shown after 5 1/2 of fluoridation. The free smooth surfaces (buccal and labial) show

  4. The Effect of Carbon Source and Fluoride Concentrations in the "Streptococcus Mutans" Biofilm Formation

    Paulino, Tony P.; Andrade, Ricardo O.; Bruschi-Thedei, Giuliana C. M.; Thedei, Geraldo, Jr.; Ciancaglini, Pietro

    2004-01-01

    The main objective of this class experiment is to show the influence of carbon source and of different fluoride concentrations on the biofilm formation by the bacterium "Streptococcus mutans." The observation of different biofilm morphology as a function of carbon source and fluoride concentration allows an interesting discussion regarding the…

  5. Origins of conductivity improvement in fluoride-enhanced silicon doping of ZnO films.

    Rashidi, Nazanin; Vai, Alex T; Kuznetsov, Vladimir L; Dilworth, Jonathan R; Edwards, Peter P

    2015-06-01

    Fluoride in spray pyrolysis precursor solutions for silicon-doped zinc oxide (SiZO) transparent conductor thin films significantly improves their electrical conductivity by enhancing silicon doping efficiency and not, as previously assumed, by fluoride doping. Containing only earth-abundant elements, SiZO thus prepared rivals the best solution-processed indium-doped ZnO in performance. PMID:25879727

  6. [Analysis of fluoride concentration in mineral waters in the Araraquara region in Brazil].

    Brandão, I M; Valsecki Júnior, A

    1998-10-01

    It has been shown that people of all ages can benefit from the topical and systemic effects of water fluoridation. However, the increase in consumption of bottled water, either to substitute for or supplement consumption of water from public sources, has implications for safe fluoride supplementation. Taking that into consideration, in 1995 we analyzed the fluoride content in 31 commercial brands of mineral water in the region of Araraquara, state of São Paulo, Brazil. Fluoride concentration as determined by our analysis was compared to the concentration of fluoride specified on each label. Only 25% of the products studied listed the fluoride concentration on their labels. In addition, among 31 mineral water brands, 26 listed the date when the chemical analysis to determine chemical composition had been performed. Of these, 20 had not been put through the annual chemical analysis determined by Brazilian law. Based on these results, if the mineral waters tested had been the only source of drinking water, fluoride supplementation would have been necessary in 69% of the samples analyzed. In the case of children up to 6 years of age who use products containing fluoride, such as topical gels, mouthwashes or toothpastes, supplementation should be recommended only if commercially bottled water is the only source of water used, not only for drinking but for cooking as well. PMID:9924506

  7. Exposure to Fluoride in Smelter Workers in a Primary Aluminum Industry in India

    A Singh

    2013-04-01

    Full Text Available Background: Fluoride is used increasingly in a variety of industries in India. Emission of fluoride dust and fumes from the smelters of primary aluminum producing industries is dissipated in the work environment and poses occupational health hazards.Objective: To study the prevalence of health complaints and its association with fluoride level in body fluids of smelter workers in a primary aluminum producing industry.Methods: In an aluminum industry, health status of 462 smelter workers, 60 supervisors working in the smelter unit, 62 non-smelter workers (control group 1 and 30 administration staff (control group 2 were assessed between 2007 and 2009. Their health complaints were recorded and categorized into 4 groups: 1 gastro-intestinal complaints; 2 non-skeletal manifestations; 3 skeletal symptoms; and (4 respiratory problems. Fluoride level in body fluids, nails, and drinking water was tested by an ion selective electrode; hemoglobin level was tested using HemoCue.Results: The total complaints reported by study groups were significantly higher than the control groups. Smelter workers had a significantly (pConclusions: Industrial emission of fluoride is not the only important sources of fluoride exposure—consumption of substance with high levels of fluoride is another important route of entry of fluoride into the body. Measurement of hemoglobin provides a reliable indicator for monitoring the health status of employees at risk of fluorosis.

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

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

  9. A niobium water target for routine production of [F-18]Fluoride with a MC 17 cyclotron

    Siikanen, J.; Ohlsson, T.; Medema, J.; Van-Essen, J.; Sandell, A.

    2013-01-01

    A [F-18]Fluoride water target was constructed for a Scanditronix MC 17 cyclotron, without a beam line, with a typical wide beam of similar to 30 x 5 mm(2). Niobium was used as target chamber material. One hour irradiation with 45 mu A protons yields about 110 GBq [F-18] Fluoride. The saturation yiel

  10. Design Manual: Removal of Fluoride from Drinking Water Supplies by Activated Alumina

    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)...

  11. Electrochemical properties of phosphorus compounds in fluoride melts

    Thisted, Elke William

    2003-01-01

    In the present work the behaviour of phosphorus species in fluoride-based melts was investigated. The motivation for the study was based on the deleterious effect of phosphorus on the aluminium production process. It is “known” that for each 100 ppm phosphorus (P) in the bath the current efficiency is reduced by 1%. In addition, the properties of cast alloys are influenced by the phosphorus content.The thesis contains a literature review on the chemistry of phosphorus with focus on its behavi...

  12. Measurements and simulations of Cherenkov light in lead fluoride crystals

    P. Achenbach(Mainz U., Inst. Phys); Baunack, S.; Grimm, K.; Hammel, T.; von Harrach, D.,; Ginja, A. Lopes; Maas, F. E.; Schilling, E.; Stroeher, H.

    2001-01-01

    The anticipated use of more than one thousand lead fluoride (PbF2) crystals as a fast and compact Cherenkov calorimeter material in a parity violation experiment at MAMI stimulated the investigation of the light yield (L.Y.) of these crystals. The number of photoelectrons (p.e.) per MeV deposited energy has been determined with a hybrid photomultiplier tube (HPMT). In response to radioactive sources a L.Y. between 1.7 and 1.9 p.e./MeV was measured with 4% statistical and 5% systematic error. ...

  13. Hydrostatic pressure dependence of elastic constants for lead fluoride crystal

    The variations of the second order elastic constants (SOEC) and longitudinal and shear moduli with hydrostatic pressure for the lead fluoride have been investigated theoretically, for the first time, by means of a three-body force potential (TBP) model. The significance of three-body interactions (TBI) has been clearly demonstrated in these investigations. The present TBP model has reproduced the pressure derivatives of the SOEC of PbF more satisfactorily than the shell model and other model calculations. (author). 24 refs, 3 figs, 2 tabs

  14. Resistance switching in polyvinylidene fluoride (PVDF) thin films

    Pramod, K.; Sahu, Binaya Kumar; Gangineni, R. B., E-mail: rameshg.phy@pondiuni.edu.in [Department of Physics, Pondicherry University, R. V. Nagar, Kalapet, Puducherry – 605014 (India)

    2015-06-24

    Polyvinylidene fluoride (PDVF), one of the best electrically active polymer material & an interesting candidate to address the electrical control of its functional properties like ferroelectricity, piezoelectricity, pyroelectricity etc. In the current work, with the help of spin coater and DC magnetron sputtering techniques, semi-crystallized PVDF thin films prominent in alpha phase is prepared in capacitor like structure and their electrical characterization is emphasized. In current-voltage (I-V) and resistance-voltage (R-V) measurements, clear nonlinearity and resistance switching has been observed for films prepared using 7 wt% 2-butanone and 7 wt% Dimethyl Sulfoxide (DMSO) solvents.

  15. Infrared study of γ irradiated fluoride optical fibers

    In order to develop infrared optical fiber systems in nuclear media, studies are made to know the behavior on line of fluoride glass optical fibers under irradiation. The increase of induced loss and the influence of the dose rate are given at 2.4 microns. Cycles of relaxation at room temperature and γ ray exposure allows an important bleaching and an unaffected kinetic of losses. Characterization of defects created by γ radiation on bulk of ZBLA glass is carried out by means of electron spin resonance (ESR). A linear kinetic of ESR signal with dose is observed and possible models for defects are discussed

  16. Corrosion Behavior of Alloys in Molten Fluoride Salts

    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

  17. Development of fluorides for high power laser optics

    The laser-assisted thermonuclear fusion program has significant needs for improved optical materials with high transmission in the ultraviolet, and with low values of nonlinear index of refraction. Lithium fluoride (LiF) possesses a combination of optical properties which are of potential use. Single-crystalline LiF is limited by low mechanical strength. In this program, we investigated the technique of press-forging to increase the mechanical strength. LiF single crystals were press-forged over the temperature range 300 to 6000C to produce fine-grained polycrystalline material

  18. Chemical treatment of ammonium fluoride solution in uranium reconversion plant

    A chemical procedure is described for the treatment of the filtrate, produced from the transformation of uranium hexafluoride (U F6) into ammonium uranyl carbonate (AUC). This filtrate is an intermediate product in the U F6 to uranium dioxide (U O2) reconversion process. The described procedure recovers uranium as ammonium peroxide fluoro uranate (APOFU) by precipitation with hydrogen peroxide (H2 O2), and as later step, its calcium fluoride (CaF2) co-precipitation. The recovered uranium is recycled to the AUC production plant. (author)

  19. Toxicity levels to humans during acute exposure to hydrogen fluoride

    A literature review was conducted of the acute toxicity of hydrogen fluoride (HF) with emphasis on the effects of inhalation of gaseous HF. The data and findings of the relevant references were summarized under four categories: animal studies, controlled human studies, community exposure and industrial exposure. These were critically reviewed and then lethal concentration-time relationships were developed for humans, corresponding to LCsub(LO), LCsub(10) and LCsub(50) levels. The effects of age, health and other physiological variables on the sensitivity to HF were discussed, as well as antagonistic and synergistic effects with other substances

  20. Resistance switching in polyvinylidene fluoride (PVDF) thin films

    Polyvinylidene fluoride (PDVF), one of the best electrically active polymer material & an interesting candidate to address the electrical control of its functional properties like ferroelectricity, piezoelectricity, pyroelectricity etc. In the current work, with the help of spin coater and DC magnetron sputtering techniques, semi-crystallized PVDF thin films prominent in alpha phase is prepared in capacitor like structure and their electrical characterization is emphasized. In current-voltage (I-V) and resistance-voltage (R-V) measurements, clear nonlinearity and resistance switching has been observed for films prepared using 7 wt% 2-butanone and 7 wt% Dimethyl Sulfoxide (DMSO) solvents