WorldWideScience

Sample records for ammonium fluorides

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

    Science.gov (United States)

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

    2016-06-01

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

  2. Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

    Institute of Scientific and Technical Information of China (English)

    由芳田; 黄世华; 时秋峰

    2010-01-01

    The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...

  3. Synthesis of uranium fluorides from uranium dioxide with ammonium bifluoride and ammonolysis of uranium fluorides to uranium nitrides

    Science.gov (United States)

    Yeamans, Charles Burnett

    This work presents the chemical conversion of uranium oxides to uranium fluorides, and their subsequent conversion to uranium nitrides. Uranium dioxide reacts with ammonium bifluoride at 20°C to form compound in the ammonium-uranium fluoride chemical system. This reaction occurs between solid uranium dioxide at the surface of the particles and ammonium fluoride vapor. A shrinking-sphere model demonstrated surface reaction kinetics, not mass transport by diffusion through the product layer, limit the reaction rate when the starting material consists of 100 mum uranium dioxide particles. Powder x-ray diffraction showed the reaction to be complete within 8 hours, with (NH4) 4UF8 the reaction product. High-resolution electron microcopy revealed the product is largely amorphous on a micrometer-scale, but contains well-formed crystal domains on the order of 10x10 nm. X-ray diffraction showed the reaction progresses though beta-NH4UF5, delta-(NH 4)2UF6, and gamma-(NH4)2UF6 intermediate phases before finally forming (NH4)4UF 8. Modeling the system as a series of first-order reaction suggested a fourth intermediate, possibly UF4, is likely to occur. The reaction of (NH4)4UF8 with ammonia gas at 800°C forms alpha-U2N3/UN2 solid solution products with a composition of UN1.83. The x-ray powder diffraction pattern of this product is the fcc pattern commonly referenced as that of UN2 and the lattice parameter was 0.53050 nm. Surface area increased by a factor of ten during ammonolysis, consistent with the action of a hydriding agent. The alpha-U2N 3/UN2 solid solution system formed contained 1 wt% UO 2 as an impurity. Upon subsequent heating to 1150°C for 4.5 hours under argon, the nitride sample formed UN with a UO2 impurity of 9 wt%. Based on the HRTEM images, oxidation in the UN product appears to be limited to within 20 nm of particle surfaces and grain boundaries.

  4. Catalytic degradation of the nerve agent VX by water-swelled polystyrene-supported ammonium fluorides.

    Science.gov (United States)

    Marciano, Daniele; Goldvaser, Michael; Columbus, Ishay; Zafrani, Yossi

    2011-10-21

    The catalytic degradation of the nerve agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) by water-swelled polymer-supported ammonium fluorides is described. VX (0.06-0.53 mol/mol F(-)) is rapidly degraded (t(1/2) ∼ 10-30 min) to form the "G-analogue" (O-ethyl methylphosphonofluoridate), which hydrolyzes (t(1/2) ∼ 1-1.5 h) to the nontoxic EMPA (ethyl methylphosphonic acid). The toxic desethyl-VX is not formed. The catalytic effect of fluoride is maintained even when 6 equiv of VX are loaded. GB (O-isopropyl methylphosphonofluoridate) and desethyl-VX agents are also degraded under these conditions.

  5. 氟化铵制备氟化钙最优条件研究%Optimized Conditions for Calcium Fluoride Preparation by Ammonium Fluoride

    Institute of Scientific and Technical Information of China (English)

    廖靖华; 王丽琼

    2014-01-01

    试验采用氟化铵与石灰石粉、石灰乳反应制取氟化钙,研究了反应温度、物料浓度、物料过量系数等各主要参数变化对氟化钙结晶、过滤速度、氟收率及其含量的影响,摸索出最优反应条件。%The ammonium fluoride was used during the experiment together with the limestone powder and lime milk to extract calcium fluoride through reaction.The reaction temperature,material concentration and excess coef-ficient were analyzed to find out their impact on the crystallization of calcium fluoride,filtering speed,fluoride yield and content.The optimized reaction conditions was explored.

  6. Fluoride

    Science.gov (United States)

    ... prescribed for children and adults whose homes have water that is not fluoridated (already has fluoride added). ... call your doctor immediately: unusual increase in saliva salty or soapy taste stomach pain upset stomach vomiting ...

  7. Preparation of conversion coating on Ti-6Al-4V alloy in mixed solution of phytic acid and ammonium fluoride through chemical modification

    Science.gov (United States)

    Li, Lanlan; He, Jian; Yang, Xu

    2016-05-01

    Conversion coatings on Ti-6Al-4V alloy was prepared through chemical modification in phytic acid and ammonium fluoride mixed solution. The influences of pH, time and the composition of solution on the microstructure of alloy surface were investigated. Scanning electron microscopy was used to observe the microstructure. The chemical composition of alloy surface before and after modification was investigated by energy dispersive X-ray spectroscopy. The results indicated that a conversion coating could be formed on the Ti-6Al-4V alloy in a mixed solution of phytic acid and ammonium fluoride, the growth and microstructure of the conversion coatings were critically dependent on the pH, time and concentration of phytic acid and ammonium fluoride. In 100 mg/ml phytic acid containing 125 mg/ml ammonium fluoride solution with a pH of 6, a compact conversion coating with the thickness of about 4.7 μm formed after 30 min immersion on Ti-6Al-4V alloy surface. The preliminary evaluation of bioactivity of conversion coating was performed by in vitro cell experiments. The results showed that this chemical modification method is a promising surface modification technique for Ti-6Al-4V alloy inplants.

  8. The study of the process of alkaline precipitation purification of solutions from silicon macroscales in the ammonium-fluoride processing of beryllium-containing materials

    Directory of Open Access Journals (Sweden)

    Dyachenko Alexander

    2016-01-01

    Full Text Available The ammonium-fluoride method of beryllium materials processing is examined. An analysis of the existing sulfuric-acid and fluoride processing scheme of beryllium-containing concentrates processing is described; advantages of the proposed ammonium-fluoride scheme and possible problems that may occur when testing a new technique are discussed. Studies on determining the effect of silicon macroscales on the behavior of beryllium in fluoride solutions at an increased pH, as well as on establishing the distribution of beryllium and silicon by phases in laboratory testing of the technology on model mixtures, are described. As a result of the studies, it is found that precipitation purification of solutions from silicon with a solution of ammonia is possible at a temperature of 20-25 °C. The paper presents data on the effect of an excessive concentration of ion-fluoride in a solution on the pH level of silicon precipitation; and on the hydrolysis degree of beryllium and silicon during the precipitation.

  9. Reuse of ammonium fluoride generated in the uranium hexafluoride conversion; Reutilizacao do fluoreto de amonio gerado na reconversao do hexafluoreto de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Silva Neto, J.B.; Carvalho, E.F. Urano de; Durazzo, M., E-mail: jbsneto@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Riella, H.G [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2010-07-01

    The Nuclear Fuel Centre of IPEN / CNEN - SP develops and manufactures dispersion fuel with high uranium concentration to meet the demand of the IEA-R1 reactor and future research reactors planned to be constructed in Brazil. The fuel uses uranium silicide (U{sub 3}Si{sub 2}) dispersed in aluminum. For producing the fuel, the processes for uranium hexafluoride (UF{sub 6}) conversion consist in obtaining U{sub 3}Si{sub 2} and / or U{sub 3}O{sub 8} through the preparation of intermediate compounds, among them ammonium uranyl carbonate - AUC, ammonium diuranate - DUA and uranium tetrafluoride - UF{sub 4}. This work describes a procedure for preparing uranium tetrafluoride by a dry route using as raw material the filtrate generated when producing routinely ammonium uranyl carbonate. The filtrate consists primarily of a solution containing high concentrations of ammonium (NH{sub 4}{sup +}), fluoride (F{sup -}), carbonate (CO{sub 3}{sup --}) and low concentrations of uranium. The procedure is basically the recovery of NH{sub 4}F and uranium, as UF{sub 4}, through the crystallization of ammonium bifluoride (NH{sub 4}HF{sub 2}) and, in a later step, the addition of UO{sub 2}, occurring fluoridation and decomposition. The UF{sub 4} obtained is further diluted in the UF{sub 4} produced routinely at IPEN / CNEN-SP by a wet route process. (author)

  10. Structural and Ionic Transport Properties of Protonic Conducting Solid Biopolymer Electrolytes Based on Carboxymethyl Cellulose Doped with Ammonium Fluoride.

    Science.gov (United States)

    Ramlli, M A; Isa, M I N

    2016-11-10

    Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transference number measurement (TNM) techniques were applied to investigate the complexation, structural, and ionic transport properties of and the dominant charge-carrier species in a solid biopolymer electrolyte (SBE) system based on carboxymethyl cellulose (CMC) doped with ammonium fluoride (NH4F), which was prepared via a solution casting technique. The SBEs were partially opaque in appearance, with no phase separation. The presence of interactions between the host polymer (CMC) and the ionic dopant (NH4F) was proven by FT-IR analysis at the C-O band. XRD spectra analyzed using Origin 8 software disclose that the degree of crystallinity (χc%) of the SBEs decreased with the addition of NH4F, indicating an increase in the amorphous nature of the SBEs. Analysis of the ionic transport properties reveals that the ionic conductivity of the SBEs is dependent on the ionic mobility (μ) and diffusion of ions (D). TNM analysis confirms that the SBEs are proton conductors.

  11. Ammonium iron(III phosphate(V fluoride, (NH40.5[(NH40.375K0.125]FePO4F, with ammonium partially substituted by potassium

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2009-01-01

    Full Text Available The title compound, ammonium potassium iron(III phosphate fluoride, (NH40.875K0.125FePO4F, is built from zigzag chains ∞1{[FeO4F2]7−}, with Fe3+ in a distorted octahedral coordination, extending along both the [011] and [0overline{1}1] directions. These chains are made up of alternating trans-[FeO4F2] and cis-[FeO4F2] octahedra via shared F-atom corners, and are linked by PO4 tetrahedra, resulting in an open-framework structure with channels along the [010] and [100] directions. There are two crystallographically independent ammonium sites: one in the [010] channels and the other, partially substituted by K+ ions, in the [100] channels. The ammonium in the [010] channels is fixed to the framework via eight hydrogen bonds (six N—H...O and two N—H...F.

  12. 由铵盐制备高纯氟化钡的工艺研究%Preparation technology of high purity barium fluoride from ammonium salt

    Institute of Scientific and Technical Information of China (English)

    许春晓; 刘晓红; 柯春兰; 章小明

    2011-01-01

    以氟化铵和氯化钡为原料,采用沉淀法制备了氟化钡.反应温度为25℃,反应时间为60min,氯化钡初始质量分数为10%,氟化铵与氯化钡物质的量比为2.2,m(洗水):m(滤饼)=10:1,可制备出纯度达99%以上的氟化钡.XRD谱图表明,样品氟化钡的所有衍射峰均与标准立方相氟化钡吻合,属立方晶系.该工艺流程简单,经济效益好.%Barium fluoride (BaF2 ) was prepared by precipitation method with ammonium fluoride and barium chloride as raw materials. BaF2 with purity of more than 99% can be prepared when reaction temperature is 25 ℃ ,reaction time is 60 rnin,initial mass fraction of barium chloride is 10% ,amount-of-substance ratio of ammonium fluoride to barium chloride is 2.2,and the mass ratio of washing water amount to filter cake amount = 10: 1. XRD pattern showed that all the diffraction peaks of barium fluoride sample were consistent with the standard cubic barium fluoride. Therefore it belongs to the cubic crystal system. The technology has short flow route and good economic benefits.

  13. Kagomé lattices as cathode: Effect of particle size and fluoride substitution on electrochemical lithium insertion in sodium- and ammonium Jarosites

    Science.gov (United States)

    Sandineni, Prashanth; Yaghoobnejad Asl, Hooman; Choudhury, Amitava

    2016-10-01

    Highly crystalline sodium and ammonium Jarosites, NaFe3(SO4)2(OH)6 and NH4Fe3(SO4)2(OH)6, have been synthesized employing hydrothermal synthesis routes. The structures consist of anionic layers of vertex-sharing FeO6 octahedra and SO4 tetrahedral units with interlayer space occupied by Na and ammonium ions, respectively. The corner-sharing FeO6 octahedral units form six and three rings similar to hexagonal tungsten bronze sheets also known as kagomé lattice. These sodium and ammonium Jarosites are thermally stable up to 400 °C and undergo facile electrochemical lithium insertion through the reduction of Fe3+ to Fe2+. Galvanostatic charge-discharge indicates that up to 2.25 and 2 lithium ions per formula unit can be inserted at an average voltage of 2.49 and 2.26 V to the sodium and the ammonium Jarosites, respectively, under slow discharge rate of C/50. The cycle-life and experimental achievable capacity show strong dependence on particle sizes and synthesis conditions. A small amount of fluoride substitution improves both achievable capacity and average voltage.

  14. Fermi level pinning characterisation on ammonium fluoride-treated surfaces of silicon by energy-filtered doping contrast in the scanning electron microscope

    Science.gov (United States)

    Chee, Augustus K. W.

    2016-08-01

    Two-dimensional dopant profiling using the secondary electron (SE) signal in the scanning electron microscope (SEM) is a technique gaining impulse for its ability to enable rapid and contactless low-cost diagnostics for integrated device manufacturing. The basis is doping contrast from electrical p-n junctions, which can be influenced by wet-chemical processing methods typically adopted in ULSI technology. This paper describes the results of doping contrast studies by energy-filtering in the SEM from silicon p-n junction specimens that were etched in ammonium fluoride solution. Experimental SE micro-spectroscopy and numerical simulations indicate that Fermi level pinning occurred on the surface of the treated-specimen, and that the doping contrast can be explained in terms of the ionisation energy integral for SEs, which is a function of the dopant concentration, and surface band-bending effects that prevail in the mechanism for doping contrast as patch fields from the specimen are suppressed.

  15. Selective inhibition of ammonium oxidation and nitrification-linked N2O formation by methyl fluoride and dimethyl ether

    Science.gov (United States)

    Miller, L.G.; Coutlakis, M.D.; Oremland, R.S.; Ward, B.B.

    1993-01-01

    Methyl fluoride (CH3F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH3F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO2- and N2O production from NH4+ in incubations of N. europaea, while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH2OH) by N. europaea and oxidation of NO2- by a Nitrobacter sp. were unaffected by CH3F or DME. In nitrifying soils, CH3F and DME inhibited N2O production. In field experiments with surface flux chambers and intact cores, CH3F reduced the release of N2O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH3F also resulted in decreased NO3- + NO2- levels and increased NH4+ levels in soils. CH3F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate- respiring bacterium, nor did it affect N2O metabolism in denitrifying soils. CH3F and DME will be useful in discriminating N2O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO2- and NO3- production.

  16. Uptake of fluoride by human surface enamel from ammonium bifluoride and consequent reduction in the penetration in vitro by caries-like lesions.

    Science.gov (United States)

    Tyler, J E; Poole, D F

    1984-01-01

    In-vitro fluoride uptake by mid-coronal, premolar enamel surfaces from topically-applied solutions of NH4HF2 was determined using a multi-electrode system for fluoride and calcium analyses. In tooth surfaces dehydrated with 100 per cent ethanol before the topical application of 1 per cent aqueous NH4HF2, there was a 2-3-fold increase in fluoride concentration up to a depth of 50 microns and fluoride enhancement to a total depth of 100 microns into the enamel. Caries-like lesions were induced in vitro in both treated and untreated enamel by the use of acidified, 6 per cent hydroxymethyl-cellulose gel containing 0.04 per cent hydroxyapatite at pH 4.5. After 120 days exposure, the mean depth of lesion penetration in the controls was 149 (+/- 34) microns. No lesions occurred in half the treated specimens; in specimens with lesions, the mean depth of penetration was 19 (+/- 3) microns. Thus, NH4HF2 was a potent inhibitor of caries-like lesion formation in vitro.

  17. Fluoridation Basics

    Science.gov (United States)

    ... Page Basic Information About Fluoride Benefits: Strong Teeth History of Fluoride in Water Cost: Saves Money, Saves Teeth Fluoride in the Water Today The mineral fluoride occurs naturally on earth and is released from rocks into the soil, ...

  18. Bottled Water and Fluoride

    Science.gov (United States)

    ... 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, ...

  19. Topaz concentrate desiliconization with ammonium bifluoride

    OpenAIRE

    Andreev, V. A.; Buynovskiy, A. S.; Andreev, Artyom Andreevich; Dyachenko, Alexander Nikolaevich

    2007-01-01

    Fluoridizing agent for the process of topaz concentrate desiliconization has been selected, topaz thermodynamic potentials have been appraised, thermodynamic probabilities of fluorination reaction of topaz concentrate main constituents have been calculated. The results of studying the concentrate desiliconization process with ammonium bifluoride by the methods of thermogravimetry, RFA, microphotography are presented

  20. Environmental fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Marier, J.R.; Rose, D.

    1971-01-01

    Modern-day man is probably exposed to more environmental fluoride than was heretofore suspected, and consideration must be given to the total ingestion from various sources as well as the types of fluoride present in air, foods, beverages, and other commodities. An effort should also be made to study the symptomology of chronic fluorine intoxication, especially the early non-skeletal manifestations of arthritic-like symptoms that may be complicated by metabolic and/or nutritional inadequacies. Finally, it must be emphasized again that dental fluorosis (i.e. mottling) will only be seen in subjects who have been exposed to fluoride during the time when the enamel of the permanent teeth is being formed, and its absence cannot be assumed to indicate freedom from other fluoride-induced effects including effects of organofluorides and their metabolites. 168 references.

  1. Other Fluoride Products

    Science.gov (United States)

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Other Fluoride Products Recommend on Facebook Tweet Share Compartir ... Use the information listed below to compare the other fluoride products that may lower the risk for ...

  2. PREPARATION AND CHARACTERIZATION OF STRONTIUM FLUORIDE POWDERS ACTIVATED BY NEODYMIUM FLUORIDE

    Directory of Open Access Journals (Sweden)

    S. V. Kuznetsov

    2015-07-01

    Full Text Available Subject of Study. The paper deals with preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry. Method. Nitrate of strontium, neodymium nitrate hexahydrate, with the content equal to 99. 99 % of the basic substance and ammonium fluoride were used as the source of substances. Activated powders of strontium fluoride were obtained by the method of deposition from aqueous solutions by washing the precipitate with a solution of ammonium fluoride, taken over 114 - 120% from stoichiometry. The washed precipitate was centrifuged for 5-7 min, dried in the air at 30-350 C. Heat treatment of the dried precipitate was carried out in two stages: the first stage at the temperature of 200- 2500 C for 0.5-1 hour, the second one at 550- 6000 C for 2-3 hours. X-ray analysis of the synthesized samples was carried out on a Bruker D8 Advance diffractometer, radiation Cu K. The size and shape measuring of the particles of activated strontium fluoride was carried out by means of electron microscope Carl Zeiss NVision 40. The content of neodymium in activated powders of strontium fluoride was determined by the method of spectral emission analysis on the device LEA - S500. Chemical analysis for determination of ammonium ion (NH4+ content in the obtained samples was performed by the method of Kjeldahl. Calculations of lattice parameters, size of coherent scattering regions and the values of micro-deformations were carried out by TOPAS program. Main Results. Preparation processes of ultradisperse, homogeneous powder Sr1-хNdхF2+х (х= 0.003-0.2, with use of ammonium fluoride as the fluorinating agent taken over 114-120 % from stoichiometry, provides obtaining the firm solution Sr1-x-yNdx(NH4yF2+x-y of the cubic fluorite structure. It has been found out that the morphology and size of the resulting product depend on the quantity of

  3. Spectrographic determination of impurities in ammonium hydrogen fluoride samples. II. Study of the behaviour of the added matrices; Determinacion espectrografica de impurezas en bibluoruro amonico. II. Estudio del comportamiento de las matrices adicionadas

    Energy Technology Data Exchange (ETDEWEB)

    Alduan, F. A.; Roca, M.; Capdevila, C.

    1979-07-01

    In order to account for the variations In the shape of the excitation-volatilization' curves and the values of the line intensities of the different impurities determined in ammonium bifluoride, the behaviour of the added matrices (graphite, 63203, GeO{sub 2}, MgO and ZnO) has been considered. With this aim the influence of the added matrices on the are discharge parameters (temperature and electronic concentration) and on the exhaustion rate of the electrode load as a function of the excitation time has been studied. On the other hand, the curve of variation of the line intensity of the metallic component of each matrix versus time has been obtained and the residues in the electrode cavity have been investigated by X-ray powder diffraction. (Author) 7 refs.

  4. Fluoride varnish or fluoride mouth rinse?

    DEFF Research Database (Denmark)

    Keller, M K; Klausen, B J; Twetman, S

    2016-01-01

    OBJECTIVE: In many Danish communities, school-based fluoride programs are offered to children with high caries risk in adjunct to tooth brushing. The purpose of this field trial was to compare the caries-preventive effectiveness of two different fluoride programs in 6-12 year olds. BASIC RESEARCH...... different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. INTERVENTIONS: One group received a semi-annual fluoride varnish applications (FV) and the other group continued with an existing program with fluoride mouth rinses once per...... in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program....

  5. Fluoride in diet

    Science.gov (United States)

    Diet - fluoride ... bones and teeth. Too much fluoride in the diet is very rare. Rarely, infants who get too ... of essential vitamins is to eat a balanced diet that contains a variety of foods from the ...

  6. Insensitive Ammonium Nitrate.

    Science.gov (United States)

    is reduced by replacing the ammonium nitrate with a solid solution of potassium nitrate in form III ammonium nitrate wherein the potassium nitrate...constitutes from more than zero to less than 50 weight percent of the solid solution . (Author)

  7. Fluoride glass fiber optics

    CERN Document Server

    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

  8. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Directory of Open Access Journals (Sweden)

    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.

  9. Synthesis of reagents for fluoride technologies

    Institute of Scientific and Technical Information of China (English)

    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.

  10. Elevated ammonium levels

    DEFF Research Database (Denmark)

    Søgaard, Rikke; Novak, Ivana; MacAulay, Nanna

    2012-01-01

    ]glutamate uptake and glutamate transport currents but had no effect on EAAT2. The maximal EAAT3-mediated glutamate transport current was increased but the apparent affinities for glutamate and Na(+) were unaltered. Ammonium did not affect EAAT3-mediated transient currents, indicating that EAAT3 surface expression...... was not enhanced. The ammonium-induced stimulation of EAAT3 increased with increasing extracellular pH, suggesting that the gaseous form NH(3) mediates the effect. An ammonium-induced intracellular alkalinization was excluded as the cause of the enhanced EAAT3 activity because 1) ammonium acidified the oocyte...... cytoplasm, 2) intracellular pH buffering with MOPS did not reduce the stimulation, and 3) ammonium enhanced pH-independent cysteine transport. Our data suggest that the ammonium-elicited uptake stimulation is not caused by intracellular alkalinization or changes in the concentrations of cotransported ions...

  11. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse......, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. CONCLUSIONS: This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam...

  12. PRODUCTION OF THORIUM FLUORIDE

    Science.gov (United States)

    Zachariasen, W.H.

    1959-08-11

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

  13. Fluoride varnishes and enamel caries

    NARCIS (Netherlands)

    Bruyn, Hugo de

    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 appl

  14. Salt fluoridation and oral health

    OpenAIRE

    Thomas M. Marthaler

    2013-01-01

    The aim of this paper is to make known the potential of fluoridated salt in community oral health programs, particularly in South Eastern Europe. Since 1922, the addition of iodine to salt has been successful in Switzerland. Goiter is virtually extinct. By 1945, the 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,...

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    the levels with and without parallel use of fluoride toothpaste. DESIGN: Fifteen healthy children were enrolled to a randomized crossover trial that was performed in two parts: Part I with twice-daily tooth brushing with fluoride toothpaste and Part II with twice-daily brushing with a non-fluoride toothpaste......: There was a statistically significant increase in the 6-h fluoride excretion after application of both experimental varnishes, with and without parallel use of fluoride toothpaste (P toothpaste was used, the mean fluoride excretion was 0.20 mg/6 h after application of Duraphat and 0.29 mg/6 h...... after application of Profluorid Varnish (P = 0.18). CONCLUSIONS: Topical applications of 0.1 mL of fluoride varnish significantly increased the 6-h fluoride excretion. As some individuals displayed excretion levels exceeding the optimal fluoride exposure, a restricted use of fluoride toothpaste...

  16. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    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 p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...

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

    Data.gov (United States)

    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...

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

    Data.gov (United States)

    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...

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

    Science.gov (United States)

    Nordbö, H; Eriksen, H M

    1976-11-01

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

  20. Heavy Metal Fluoride Glasses.

    Science.gov (United States)

    1987-04-01

    i 2N E ihhhhh1112h MEmhhhhEEEohhhhE I.’....momo 111111111’-20 LA ’Ll2. AFWL-TR-86-37 AFWL-TR- 86-37 oT C ,l C ’-’ N HEAVY METAL FLUORIDE GLASSES 0nI...Secwrit CkasmfcationJ HEAVY METAL FLUORIDE GLASSES 12. PERSONAL AUTHOR(S) Reisfield, Renata; and Eyal, Mrek 13. TYPE OF REPORT 113b. TIME COVERED 114...glasses containing about 50 mole% of ZrF4 [which can be replaced by HfF 4 or TIF 4 (Refs. 1-3) or heavy metal fluorides based on PbF2 and on 3d-group

  1. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after an el...... brushing with fluoride toothpaste....

  2. 四乙基氢氧化铵改性聚偏氟乙烯接枝聚丙烯酸油水分离膜的制备%Synthesis of Oil/Water Separation Membranes via Grafting Acrylic Acid onto Poly(vinylidene fluoride) Modified by Tetraethyl Ammonium Hydroxide†

    Institute of Scientific and Technical Information of China (English)

    闫凯波; 郭贵宝; 刘金彦

    2016-01-01

    使用四乙基氢氧化铵( TEAH)液相本体改性聚偏氟乙烯( PVDF),以过氧化苯甲酰( BPO)为引发剂,将丙烯酸( AA)接枝到改性PVDF骨架上,合成了聚偏氟乙烯接枝聚丙烯酸( PVDF-g-PAA)共聚物,通过浸没沉淀法制备了PVDF-g-PAA亲水性油水分离膜.通过傅里叶变换红外光谱( FTIR)、扫描电子显微镜( SEM)和过滤试验分析了膜的结构和分离性能.研究了不同接枝条件对PVDF-g-PAA膜接枝率的影响.同时,通过膜接枝率与膜表面接触角的关系确定最佳接枝条件.结果表明, TEAH使PVDF脱去HF产生碳碳双键且PAA接枝到改性的PVDF骨架上,膜内外孔隙分布均匀; PVDF-g-PAA膜的接触角随着接枝率的提高而降低.接枝单体AA含量为45%,接枝温度为85℃,接枝4 h制备的PVDF-g-PAA膜的接枝率为20.1%,孔隙度为65.3%,平均孔径为78.0 nm,接触角为57.5°,且在60 s内接触角降至14.3°;纯水通量提高到571.33 L/( m2·h),截留率和水通量恢复率分别达到94.3%和88.7%,且通量衰减率仅为9.8%.与纯PVDF膜相比, PVDF-g-PAA膜的分离性能显著提高.%Poly(vinylidene fluoride)-graft-poly(acrylic acid)(PVDF-g-PAA) membranes were prepared via phase bulk modification in tetraethyl ammonium hydroxide(TEAH) liquid, grafting acrylic acid(AA) onto PVDF by benzoyl peroxide( BPO) as a initiator. After that, the copolymer was casted into a flat membrane via immersion phase inversion. The chemical composition, morphology and the separation performance of the PVDF-g-PAA membrane were charaterized. Moreover, the effect of variable grafting conditions on grafting de-gree was investigated as well as the optimal surface contact angle for the grafting ration was obtained. It was proved that the PVDF was taken off HF to produce carbon double bonds and acrylic acid was grafted onto the modified PVDF backbones, forming a homogeneous pore distribution in interior and exterior of the membrane. The water contact angle of PVDF

  3. Relationships of human plasma fluoride and bone fluoride to age

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, F.M.; Tinanoff, N.; Moutinho, M.; Anstey, M.B.; Waziri, M.H.

    1976-04-01

    There is evidence that fluoride levels in plasma correlate with the fluoride content in bones. The authors determined whether or not fluoride in plasma and bones might correlate with age. In 41 in-patients at the University Hospital, Iowa City, 36 of whom had been residing in fluoridated communities plasma fluoride was determined in the fasting stage by the fluoride ion selective electrode. The teeth of these children were compared with those of a neighboring city where the natural fluoride content in drinking water was 0.1 ppm. For the second sampling 42 months following the beginning of the program only 10 and 11 year old children - who had been 6 and 7 years old at the beginning of the experiment - were selected. Twenty-five boys and girls in each group were compared with a similar group of children as controls. After 28 months (approximately 33 rinsing with sodium fluoride solution) the DMF index in the fluoride-treated children was 18.4% less than in the controls. In the second group among 10 and 11 year old children after 42 months with 55 rinsings the difference was 35.0%. The author acknowledged that factors other than applications of sodium fluoride may have contributed to the prevention of caries in the fluoride-treated groups.

  4. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... an 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...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse...

  5. Salt fluoridation and oral health

    Directory of Open Access Journals (Sweden)

    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.

  6. Health Effects Associated with Water Fluoridation.

    Science.gov (United States)

    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)

  7. Industrial fluoride pollution: chronic fluoride poisoning in Cornwall Island cattle

    Energy Technology Data Exchange (ETDEWEB)

    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 was designated as the major source of fluoride emissions impacting on Cornwall Island. Cattle located on this island showed signs of chronic fluoride poisoning. This poisoning was manifested clinically by stunted growth and dental fluorosis to a degree of severe interference with drinking and mastication. This Cornwall Island herds study indicates that the established tolerance level of fluoride for performance of dairy and beef cattle is not valid since the tolerance level was set based on experiments with healthy calves which were exposed to dietary fluoride from 3 to 4 months of age and not on cattle which were chronically exposed to fluoride from conception to death. 56 references.

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

    Science.gov (United States)

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

    2012-07-30

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

  9. Alternative process to produce UF{sub 4} using the effluent from ammonium uranyl carbonate route

    Energy Technology Data Exchange (ETDEWEB)

    Silva Neto, Joao B.; Garcia, Rafael Henrique Lazzari; Dal Vechio, Edvaldo, E-mail: jbsneto@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), SP (Brazil); Riella, Humberto G., E-mail: riella@enq.ufsc.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil); Instituto Nacional de Ciencias e Tecnologia de Reatores Nucleares Inovadores (INCT/CNPq) (Brazil); Carvalho, Elita F. Urano de; Durazzo, Michelangelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), SP (Brazil); Instituto Nacional de Ciencias e Tecnologia de Reatores Nucleares Inovadores (INCT/CNPq) (Brazil)

    2011-07-01

    The Nuclear Fuel Centre of IPEN / CNEN - SP develops and manufactures dispersion fuel with high uranium concentration. It meets the demand of the IEA-R1 reactor and future research reactors to be constructed in Brazil. The fuel uses uranium silicide (U{sub 3}Si{sub 2}) dispersed in aluminum. For producing the fuel, the process of uranium hexafluoride (UF{sub 6}) conversion consist in obtaining U{sub 3}Si{sub 2} and / or U{sub 3}O{sub 8} through the preparation of intermediate compounds, among them ammonium uranyl carbonate - AUC, ammonium diuranate - DUA and uranium tetrafluoride - UF{sub 4}. This work describes a procedure for preparing uranium tetrafluoride via a dry route, using as raw material the filtrate generated when ammonium uranyl carbonate is routinely produced. The filtrate consists mainly of a solution containing high concentrations of ammonium (NH{sup 4+}), fluoride (F{sup -}), carbonate (CO{sup 3-}) and low concentrations of uranium. The procedure consists in recovering NH{sup 4F} and uranium, as UF{sub 4}, through the crystallization of ammonium bifluoride (NH{sub 4}HF{sub 2}) and, in a later step, the addition of UO{sub 2}, occurring fluoridation and decomposition. The UF{sub 4} obtained is further diluted in the UF{sub 4} produced routinely at IPEN / CNEN-SP by a wet route process. (author)

  10. Fluoride-conversion synthesis of homogeneous actinide oxide solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Silva, G W Chinthaka M [ORNL; Hunn, John D [ORNL; Yeamans, Charles B. [University of California, Berkeley; Cerefice, Gary S. [University of Nevada, Las Vegas; Czerwinski, Ken R. [University of Nevada, Las Vegas

    2011-01-01

    Here, a novel route to synthesize (U, Th)O2 solid solutions at a relatively low temperature of 1100 C is demonstrated. First, the separate actinide oxides reacted with ammonium bifluoride to form ammonium actinide fluorides at room temperature. Subsequently, this mixture was converted to the actinide oxide solid solution using a two-phased heat treatment, first at 610 C in static air, then at 1100 C in flowing argon. Solid solutions obeying Vegard s Law were synthesized for ThO2 content from 10 to 90 wt%. Microscopy showed that the (U, Th)O2 solid solutions synthesized with this method to have considerably high crystallinity and homogeneity, suggesting the suitability of material thus synthesized for sintering into nuclear fuel pellets at low temperatures.

  11. Ammonium diphosphitoindate(III

    Directory of Open Access Journals (Sweden)

    Farida Hamchaoui

    2013-04-01

    Full Text Available The crystal structure of the title compound, NH4[In(HPO32], is built up from InIII cations (site symmetry 3m. adopting an octahedral environment and two different phosphite anions (each with site symmetry 3m. exhibiting a triangular–pyramidal geometry. Each InO6 octahedron shares its six apices with hydrogen phosphite groups. Reciprocally, each HPO3 group shares all its O atoms with three different metal cations, leading to [In(HPO32]− layers which propagate in the ab plane. The ammonium cation likewise has site symmetry 3m.. In the structure, the cations are located between the [In(HPO32]− layers of the host framework. The sheets are held together by hydrogen bonds formed between the NH4+ cations and the O atoms of the framework.

  12. Waterproofing Materials for Ammonium Nitrate

    Directory of Open Access Journals (Sweden)

    R.S. Damse

    2004-10-01

    Full Text Available This study explores the possibility of overcoming the problem of hygroscopicity of ammonium nitrate by coating the particles with selected waterproofing materials. Gravimetric analysis ofthe samples of ammonium nitrate coated with eight different waterproofing materials, vis-a-vis, uncoated ammonium nitrate, were conducted at different relative humidity and exposuretime. The results indicate that mineral jelly is the promising waterproofing material for ammonium nitrate among the materials tested, viz, calcium stearate, dioctyl phthalate, kaoline, diethylphthalate, dinitrotoluene, shelac varnish, and beeswax. Attempts were made to confirm the waterproofing ability of mineral jelly to ammonium nitrate using differential thermal analysisand x-ray diffraction patterns as an experimental tool. Suitability of mineral jelly as an additive for the gun propellant was also assessed on the basis of theoretical calculations using THERMprogram.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sivasankar, V., E-mail: vsivasankar@tce.edu [Department of Chemistry, Thiagarajar College of Engineering (Autonomous), Madurai 625015, Tamil Nadu (India); Rajkumar, S. [Department of Chemistry, Thiagarajar College of Engineering (Autonomous), Madurai 625015, Tamil Nadu (India); Murugesh, S. [Department of Chemistry, SACS M.A.V.M.M. Engineering College, Madurai 625301, Tamil Nadu (India); Darchen, A. [UMR CNRS No. 6226 Sciences Chimiques de Rennes, ENSCR, Avenue du General Leclerc, CS 50837, 35708 Rennes, Cedex 7 (France)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer The carbonization of Tamarind fruit shell improved its defluoridation efficiency. Black-Right-Pointing-Pointer Calcium carbonate particles were involved in the defluoridation process. Black-Right-Pointing-Pointer Adsorbent dose, pH, and fluoride concentration showed significant effects. Black-Right-Pointing-Pointer Maximum adsorption of fluoride was achieved at pH 7-8. Black-Right-Pointing-Pointer Prepared carbons were efficient in treating three natural waters. - Abstract: Tamarindus indica fruit shells (TIFSs) are naturally calcium rich compounds. They were impregnated with ammonium carbonate and then carbonized, leading to ammonium carbonate activated ACA-TIFS carbon. The resulting materials and carbon arising from virgin fruit shells V-TIFS were characterized and assayed as adsorbent for the removal of fluoride anions from groundwater. The fluoride scavenging ability of TIFS carbons was due to naturally dispersed calcium compounds. X-ray diffraction (XRD) showed that TIFS carbon contained a mixture of calcium oxalate and calcium carbonate. Batch studies on the fluoride removal efficiency of TIFS carbons with respect to contact time, pH, initial fluoride concentration, and co-ion interference were conducted. Applicability of various kinetic models (viz., pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich) and sorption isotherms were tested for batch techniques. The fluoride removal capacity of TIFS carbons was found to be 91% and 83% at a pH of 7.05 for V-TIFS and ACA-TIFS carbons, respectively. The practical applicability of TIFS carbons using groundwater samples was approved. The fluoride removal was greater in groundwater without hydrogen carbonate ions than those containing these ions. The characterizations of fluoride unloaded and loaded TIFS carbons were done by SEM and XRD studies.

  14. Ammonium Perchlorate and Ammonium Perchlorate- Hydroxyl Terminated Polybutadiene Simulated Combustion

    Directory of Open Access Journals (Sweden)

    Rene Francisco Boschi Gonçalves

    2012-03-01

    Full Text Available The combustion simulation of ammonium perchlorate was carried out with the software Chemkin, in two steps: the burning behavior of pure ammonium perchlorate and the one of formulated ammonium perchlorate with hydroxyl terminated polybutadiene binder. In both cases, the room pressure varied in order to verify its influence in the system. The burning environment conditions were diverse. During the combustion process, the data obtained from the kinetic chemistry simulation software were compiled. The flame structure can be described by the molar fraction of the burning products and the temperature evolution from the surface of the material.

  15. 49 CFR 173.163 - Hydrogen fluoride.

    Science.gov (United States)

    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...

  16. Fluoride-induced chronic renal failure.

    Science.gov (United States)

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

    1987-08-01

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

  17. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, Neil (Orinda, CA); Whalen, J. Marc (Corning, NY); Chacon, Lisa (Corning, NY)

    2000-12-12

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

  18. 21 CFR 184.1138 - Ammonium chloride.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium chloride. 184.1138 Section 184.1138 Food... Specific Substances Affirmed as GRAS § 184.1138 Ammonium chloride. (a) Ammonium chloride (NH4Cl, CAS Reg. No. 12125-02-9) is produced by the reaction of sodium chloride and an ammonium salt in solution....

  19. 21 CFR 184.1133 - Ammonium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium alginate. 184.1133 Section 184.1133 Food... Specific Substances Affirmed as GRAS § 184.1133 Ammonium alginate. (a) Ammonium alginate (CAS Reg. No. 9005.... Ammonium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  20. FLUORIDE TOXICITY – A HARSH REALITY

    Directory of Open Access Journals (Sweden)

    Bandlapalli Pavani

    2011-04-01

    Full Text Available There are many incidents of fluoride toxicity whether it is acute or chronic. Fluoride toxicity is an environmental hazard which arises from the upper layers of geological crust and is dissolved in water. Prolonged drinking of such water causes chronic fluoride toxicity. Use of fluoride containing compounds for various purposes such as dental products, metal, glass, refrigerator and chemical industries act as a source of fluoride poisoning and increase the risk of toxicity. This review reflects the deleterious effects of fluorides on various organs in the physiological system.

  1. Polishing of quartz by rapid etching in ammonium bifluoride.

    Science.gov (United States)

    Vallin, Orjan; Danielsson, Rolf; Lindberg, Ulf; Thornell, Greger

    2007-07-01

    The etch rate and surface roughness of polished and lapped AT-cut quartz subjected to hot (90, 110, and 130 degrees C), concentrated (50, 65, 80 wt %) ammonium bi-fluoride have been investigated. Having used principal component analysis to verify experimental solidity and analyze data, we claim with confidence that this parameter space does not, as elsewhere stated, allow for a polishing effect or even a preserving setting. Etch rates were found to correlate well, and possibly logarithmically, with temperature except for the hottest etching applied to lapped material. Roughness as a function of temperature and concentration behaved well for the lapped material, but lacked systematic variation in the case of the polished material. At the lowest temperature, concentration had no effect on etch rate or roughness. Future efforts are targeted at temperatures and concentrations closer to the solubility limit.

  2. Chronic fluoride toxicity: dental fluorosis.

    Science.gov (United States)

    Denbesten, Pamela; Li, Wu

    2011-01-01

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

  3. Rationally designed porous polystyrene encapsulated zirconium phosphate nanocomposite for highly efficient fluoride uptake in waters

    Science.gov (United States)

    Zhang, Qingrui; Du, Qing; Jiao, Tifeng; Zhang, Zhaoxiang; Wang, Sufeng; Sun, Qina; Gao, Faming

    2013-01-01

    Fluoride pollution in waters has engulfed worldwide regions and an excess of fluoride intake always causes skeletal fluorosis. Herein, a novel hybrid nanomaterial ZrP-MPN was fabricated for fluoride retention by encapsulating nano-ZrP onto macroporous polystyrene materials modified with quaternary ammonium groups. The as-obtained materials exhibited favorable removal of fluoride ions from aqueous solution in presence of common anions (SO42−/NO3−/Cl−) at high contents. Moreover outstanding sorption properties were also detected by involving series of commercial adsorbents (AA/magnetite/GFH/manganese sands) as references. Such satisfactory performances might be ascribed to the structural design of nanocomposite. (1) the CH2N+(CH3)3Cl groups enhances sorption diffusion and preconcentration in sorbent phase theoretically based on Donnan membrane principle; (2) the embedded ZrP nanoparticles also devotes to the efficient adsorption capacities due to its size-dependent specific properties. Additionally, the exhausted ZrP-MPN could be regenerated readily by alkaline solution. Thus, ZrP-MPN was a promising material for fluoride retention in waters. PMID:23989688

  4. Rationally designed porous polystyrene encapsulated zirconium phosphate nanocomposite for highly efficient fluoride uptake in waters

    Science.gov (United States)

    Zhang, Qingrui; Du, Qing; Jiao, Tifeng; Zhang, Zhaoxiang; Wang, Sufeng; Sun, Qina; Gao, Faming

    2013-08-01

    Fluoride pollution in waters has engulfed worldwide regions and an excess of fluoride intake always causes skeletal fluorosis. Herein, a novel hybrid nanomaterial ZrP-MPN was fabricated for fluoride retention by encapsulating nano-ZrP onto macroporous polystyrene materials modified with quaternary ammonium groups. The as-obtained materials exhibited favorable removal of fluoride ions from aqueous solution in presence of common anions (SO42-/NO3-/Cl-) at high contents. Moreover outstanding sorption properties were also detected by involving series of commercial adsorbents (AA/magnetite/GFH/manganese sands) as references. Such satisfactory performances might be ascribed to the structural design of nanocomposite. (1) the CH2N+(CH3)3Cl groups enhances sorption diffusion and preconcentration in sorbent phase theoretically based on Donnan membrane principle; (2) the embedded ZrP nanoparticles also devotes to the efficient adsorption capacities due to its size-dependent specific properties. Additionally, the exhausted ZrP-MPN could be regenerated readily by alkaline solution. Thus, ZrP-MPN was a promising material for fluoride retention in waters.

  5. Fluoride level in saliva after bonding orthodontic brackets with a fluoride containing adhesive

    NARCIS (Netherlands)

    Ogaard, B; Arends, J; Helseth, H; Dijkman, G; vanderKuijl, M

    1997-01-01

    The fluoride level in saliva is considered an important parameter in caries prevention. Elevation of the salivary fluoride level by a fluoride-releasing orthodontic bonding adhesive would most likely be beneficial in the prevention of enamel caries. In this study, the fluoride level in saliva was me

  6. Fluoridering af drikkevandet i Danmark?

    DEFF Research Database (Denmark)

    Arvin, Erik; Spliid, Henrik; Bruvo, M.;

    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...

  7. High-fluoride groundwater.

    Science.gov (United States)

    Rao, N Subba

    2011-05-01

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

  8. Microcratering in Polyvinylidene Fluoride

    Science.gov (United States)

    Shu, Anthony John

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

  9. Molten fluorides for nuclear applications

    Directory of Open Access Journals (Sweden)

    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.

  10. Fluoride: its role in dentistry

    Directory of Open Access Journals (Sweden)

    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.

  11. The Effect of Fluoride in Osteoporosis.

    Science.gov (United States)

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

    1987-01-01

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

  12. Fluoride in African groundwater: Occurrence and mitigation

    NARCIS (Netherlands)

    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

  13. 21 CFR 582.1141 - Ammonium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammonium phosphate. 582.1141 Section 582.1141 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1141 Ammonium phosphate. (a) Product. Ammonium phosphate (mono- and dibasic). (b)...

  14. 76 FR 46907 - Ammonium Nitrate Security Program

    Science.gov (United States)

    2011-08-03

    ... and fertilizer blends containing more than 15% by weight ammonium nitrate, except liquid fertilizers... concerning the detonability of ammonium nitrate; Comments on how likely ammonium nitrate fertilizer users would be to use an alternative fertilizer that is potentially less detonable, such as Sulf-N...

  15. 76 FR 11273 - Ammonium Nitrate From Russia

    Science.gov (United States)

    2011-03-01

    ... COMMISSION Ammonium Nitrate From Russia AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the suspended investigation on ammonium nitrate from Russia... investigation on ammonium nitrate from Russia would be likely to lead to continuation or recurrence of...

  16. 76 FR 47238 - Ammonium Nitrate From Russia

    Science.gov (United States)

    2011-08-04

    ... COMMISSION Ammonium Nitrate From Russia Determination On the basis of the record \\1\\ developed in the subject... order on ammonium nitrate from Russia would be likely to lead to continuation or recurrence of material... Commission are contained in USITC Publication 4249 (August 2011), entitled Ammonium Nitrate from...

  17. 21 CFR 582.7133 - Ammonium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammonium alginate. 582.7133 Section 582.7133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Ammonium alginate. (a) Product. Ammonium alginate. (b) Conditions of use. This substance is...

  18. Special Report: Fluoridation of Water.

    Science.gov (United States)

    Hileman, Bette

    1988-01-01

    Reviews the controversy regarding water fluoridation in the United States during the last 50 years. Discusses the current status; benefits; and health risks including skeletal fluorosis, kidney disease, hypersensitivity, mutagenic effects, birth defects, and cancer. Presents statistics and anecdotal accounts. (CW)

  19. Fissure seal or fluoride varnish?

    Science.gov (United States)

    Deery, Christopher

    2016-09-01

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

  20. Phase diagram of ammonium nitrate

    Science.gov (United States)

    Dunuwille, M.; Yoo, C. S.

    2014-05-01

    Ammonium Nitrate (AN) has often subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood -resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 17 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400 °C.

  1. Global affordability of fluoride toothpaste

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

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

    2014-01-01

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

  3. Synthesis and Fluorescence of Europium-Doped Barium Fluoride Cubic Nanocolumns

    Institute of Scientific and Technical Information of China (English)

    连洪州; 刘洁; 叶泽人; 石春山

    2004-01-01

    Europium-doped barium fluoride cubic nanocolumns were synthesized from the quaternary water in oil reverse microemulsions. In this process, the aqueous cores of water/cetyl trimethyl ammonium bromide(CTAB)/n-butanol/n-octane reverse microemulsions were used as microreactors for the precipitation of europium doped barium fluoride. XRD analysis shows that under the dopant concentration of 0.06%(molar fraction), the products are single phase. The result products are cubic column-like with about 30~50 nm edge length of cross section, and about 200 nm of length obtained from the transmission electron microscopy(TEM), and atomic force microscopy(AFM). Under the 0.06%(molar fraction) of dopant concentration, the fluorescence of Eu2+ and Eu3+ under the 589 of excitation wavelength is observed.

  4. Determination of Fluoride in Various Samples and Some Infusions Using a Fluoride Selective Electrode

    OpenAIRE

    TOKALIOĞLU, Şerife; Kartal, Şenol; ŞAHİN, Uğur

    2004-01-01

    The determination of fluoride in some environmental samples was performed using a fluoride ion-selective electrode. Fluoride concentrations were determined in drinking waters (from different provinces, districts and villages in Turkey), fruit juices, bottled water samples, toothpastes and tooth powders, liquors of Turkish coffee, coffee, linden, rose hip, and various brand tea infusions, and dust samples collected from the Erciyes University campus car park. The average fluoride conc...

  5. Fluoride Importance in Controlling Caries and Fluorosis

    OpenAIRE

    Gaurav Solanki

    2012-01-01

    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, se...

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

    NARCIS (Netherlands)

    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

  7. High fluoride exposure in hemodialysis patients.

    Science.gov (United States)

    Bello, V A; Gitelman, H J

    1990-04-01

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

  8. Synthesis of Chitosan Quaternary Ammonium Salts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A series of N-alkyl or N-aryl chitosan quaternary ammonium salts were prepared via Schiffs base intermediates. Quaternization of N-substituted chitosan derivatives was carried out using methyl iodide to produce water-soluble cationic chitosan quaternary ammonium salt. The products were characterized by IR, 1HNMR and elemental analysis. The degree of substitution of chitosan quaternary ammonium salt was calculated by elemental analysis.

  9. Effects of different kinds of fluorides on enolase and ATPase activity of a fluoride-sensitive and fluoride-resistant Streptococcus mutans strain

    NARCIS (Netherlands)

    van Loveren, C.; Hoogenkamp, M.A.; Deng, D.M.; ten Cate, J.M.

    2008-01-01

    Enolase and ATPase are sensitive to fluoride. It is unclear whether this sensitivity differs for F-sensitive and F-resistant cells or for different types of fluoride. Permeabilized cells of the fluoride-sensitive strain Streptococcus mutans C180-2 and its fluoride-resistant mutant strain C180-2 FR w

  10. The comparison of calculated transition probabilities with luminescence characteristics of erbium(III) in fluoride glasses and in the mixed yttrium-zirconium oxide crystal

    Science.gov (United States)

    Reisfeld, R.; Katz, G.; Jacoboni, C.; De Pape, R.; Drexhage, M. G.; Brown, R. N.; Jørgensen, C. K.

    1983-07-01

    Fluorozirconate glasses containing 2 mole% ErF 3 were prepared by melting the binary fluorides with ammonium bifluoride under an atmosphere of carbon tetrachloride and argon at 850°C. Absorption spectra of these glasses were obtained and the Judd-Ofelt parameters were calculated. Emission spectra and lifetimes of erbium in fluorozirconate glass, in lead-gallium-zinc fluoride glass, and in yttrium-zirconium oxide crystal were measured and compared with the theoretical calculations. Laser emission lines in these materials are deduced from these measurements. It is suggested that materials doped with erbium may serve as light sources for fiber optic waveguides made from the undoped materials.

  11. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed...

  12. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126...) WATERFRONT FACILITIES HANDLING OF DANGEROUS CARGO AT WATERFRONT FACILITIES § 126.28 Ammonium...

  13. Silicon microtubes made by immersing macroporous silicon into ammonium fluoride solution

    Energy Technology Data Exchange (ETDEWEB)

    Huanca, Danilo Roque, E-mail: droqueh@usp.br [Laboratorio de sensores e Dispositivos do Instituto de Física e Química da Universidade Federal de Itajubá, Avenida BPS, 1303, CEP 37500 903 Itajubá, MG (Brazil); Laboratório de Microeletrônica da Escola Politécnica da USP, Avenida Prof. Luciano Gualberto, travessa 3 n° 380, CEP 05508-900 São Paulo, SP (Brazil); Kim, Hae Yong [Laboratório de Processamento de Sinais da Escola Politécnica da USP, Avenida Prof. Luciano Gualberto, travessa 3 n° 380, CEP 05508-900 São Paulo, SP (Brazil); Salcedo, Walter Jaimes [Laboratório de Microeletrônica da Escola Politécnica da USP, Avenida Prof. Luciano Gualberto, travessa 3 n° 380, CEP 05508-900 São Paulo, SP (Brazil)

    2015-06-15

    In this paper, we report the fabrication of silicon microtubes (SMT) by electrochemical dissolution of macroporous silicon layers immersed into aqueous solution of NH{sub 4}F mixed with Na{sub 2}SO{sub 4}, at different pH levels (4.5–9.5). Well-defined SMT have been obtained at pH 6.5, 7.5 and 9.5, whereas for other pH levels, the surface of the porous structure becomes passivated or formation of needle-like structure occurs. The mean inner diameter and the thickness of walls of the tubes shown to be depended on the pH level of the solutions. In this investigation, we obtained silicon tubes with inner diameter from 0.2 to 2.0 μm with thickness wall from about 0.23 to 0.50 μm. The investigation of these structures indicates that for tube formation the pH level and predominance of the anisotropic dissolution are necessary conditions. The tube formation cannot be explained regarding the silicon dissolution mechanism. For this aim, the role of the space charge region must be regarded. The structural characterization of silicon tubes was achieved by X-ray diffraction (XRD), X-ray energy dispersive Spectroscopy (EDS) and Raman spectroscopy and the results pointed out that these tubes are constituted by crystalline silicon structures covered by a very thin silicon oxide film. In this paper, the formation mechanism of the SMT is also discussed, highlighting the role of the space charge region (SCR) and the pH level for tube formation. - Highlights: • We fabricate silicon microtubes using macroporous silicon as a starting material. • Depending on the pH level, well-defined tubes are formed or the surface is passivate. • It was identified that the key factors for tube formation are the pH level and the space charge region.

  14. Study of ammonium fluoride passivation time on CdZnTe bulk crystal wafers

    Energy Technology Data Exchange (ETDEWEB)

    Bensalah, H.; Crocco, J.; Carcelen, V.; Plaza, J.L.; Zheng, Q.; Dieguez, E. [Crystal Growth Laboratory, Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Marchini, L. [IMEM-CNR, Parma (Italy); Zanichelli, M. [Department of Physics, University of Parma (Italy); Dominguez, G.; Soriano, L. [Departamento de Fisica Aplicada and Instituto de Ciencias de Materiales Nicolas Cabrera, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2011-07-15

    The chemical etching and the passivation processes of CdZnTe wafers were studied. The treatment effects were tested through an X-Ray Photoelectron Spectroscopy (XPS) analysis and I-V measurement. The chemical etching in 2%Br-MeOH solution may effectively remove the damaged layer and improve the ohmic contact between CdZnTe wafer and Au electrodes making rich the surface with Te. After different etching times, the CdZnTe wafers were passivated with NH{sub 4}F/H{sub 2}O{sub 2}.CdZnTe wafer passivated immediately after etching showed the best passivation efficiency because the enriched Te on the surface was fully oxidized to TeO{sub 2}, which results in the thickest oxide layer, and the most stoichiometric surface. Also the surface leakage current was reduced in comparison with the sample passivated 24 h after etching. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Science.gov (United States)

    Jenkins, G N

    1991-01-01

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

  16. Equilibrium studies of sodium-ammonium potassium-ammonium, and calcium-ammonium exchanges on clinoptilolite zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Jama, M.A.; Yuecel, H. (Middle East Technical Univ., Ankara (Turkey))

    1989-12-01

    Forward and reverse ion-exchange isotherms for the binary sodium-ammonium, potassium-ammonium, and calcium-ammonium systems on clinoptilolite have been measured in aqueous solutions at a total concentration of 0.1 equiv/dm{sup 3} and at 298 K. Prior to exchange experiments it was attempted to prepare homoionic forms of the zeolite by exhaustive treatments with appropriate salt solutions of cations. With no binary exchanges, full replacement of the cation by the ammonium ion is observed, which conflicts with some earlier work on clinoptilolite. Despite the observed partial exchange levels, clinoptilolite shows a very high preference for ammonium ion over sodium and calcium but not over potassium. Thermodynamic values for the exchanges were calculated and compared with data in the literature. Both the selectivity and thermodynamic affinity sequence, in agreement with previous work reported in the literature, are K{sup +} > NH{sub 4}{sup +} > Na{sup +} > Ca{sup 2+}.

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

    Science.gov (United States)

    ten Cate, J M

    1997-10-01

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

  18. HOUSEHOLD PURIFICATION OF FLUORIDE CONTAMINATED MAGADI (TRONA)

    DEFF Research Database (Denmark)

    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....

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Diethylenetriaminium hexafluoridotitanate(IV fluoride

    Directory of Open Access Journals (Sweden)

    J. Lhoste

    2008-11-01

    Full Text Available The title compound, (C6H21N4[TiF6]F, was synthesized by the reaction of TiO2, tris(2-aminoethylamine, HF and ethanol at 463 K in a microwave oven. The crystal structure consists of two crystallographically independent [TiF6]2− anions, two fluoride anions and two triply-protonated tris(2-aminoethylamine cations. The Ti atoms are coordinated by six F atoms within slightly distorted octahedra. The anions and cations are connected by intermolecular N—H...F hydrogen bonds.

  1. Biodegradation of rocket propellant waste, ammonium perchlorate

    Science.gov (United States)

    Naqvi, S. M. Z.; Latif, A.

    1975-01-01

    The short term effects of ammonium perchlorate on selected organisms were studied. A long term experiment was also designed to assess the changes incurred by ammonium perchlorate on the nitrogen and chloride contents of soil within a period of 3 years. In addition, an attempt was made to produce methane gas from anaerobic fermentation of the aquatic weed, Alternanthera philoxeroides.

  2. Effects of ammonium concentration and charge exchange on ammonium recovery from high strength wastewater using a microbial fuel cell

    NARCIS (Netherlands)

    Kuntke, P.; Geleij, M.; Bruning, H.; Zeeman, G.; Hamelers, H.V.M.; Buisman, C.J.N.

    2011-01-01

    Ammonium recovery using a 2 chamber microbial fuel cell (MFC) was investigated at high ammonium concentration. Increasing the ammonium concentration (from 0.07 g to 4 g ammonium-nitrogen/L) by addition of ammonium chloride did not affect the performance of the MFC. The obtained current densities by

  3. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Science.gov (United States)

    2010-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  4. The nucleation kinetics of ammonium metavanadate precipitated by ammonium chloride

    Science.gov (United States)

    Du, Guangchao; Sun, Zhaohui; Xian, Yong; Jing, Han; Chen, Haijun; Yin, Danfeng

    2016-05-01

    The nucleation kinetics of ammonium metavanadate (NH4VO3) was investigated under conditions of the simulated process for precipitation of NH4VO3 from the vanadium-containing solution. Induction periods for the nucleation of NH4VO3 were experimentally determined as a function of supersaturation at temperatures from 30 to 45 °C. Using the classical nucleation theory, the interfacial tension between NH4VO3 and supersaturated solution, the nucleation rate and critical radius of nucleus for the homogeneous nucleation of NH4VO3 were estimated. With temperature increasing, the calculated interfacial tension gradually decreased from 29.78 mJ/m2 at 30 °C to 23.66 mJ/m2 at 45 °C. The nucleation rate was found to proportionally increase but the critical radius of nucleus exponentially decreased, with increase in supersaturation ratio at a constant temperature. The activation energy for NH4VO3 nucleation was obtained from the relationship between temperature and induction period, ranging from 79.17 kJ/mol at S=25 to 115.50 kJ/mol at S=15. FT-IR and Raman spectrum indicated that the crystals obtained in the precipitation process were NH4VO3.

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

    Science.gov (United States)

    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)

  6. Ammonium sulfate preparation from phosphogypsum waste

    Directory of Open Access Journals (Sweden)

    Abdel-Hakim T. Kandil

    2017-01-01

    Full Text Available The Egyptian phosphogypsum waste is treated using sulfuric acid prior the ammonium sulfate production. The relevant factors that would affect the removal efficiencies of some impurities are studied. The optimum conditions of the treatment are 8 M sulfuric acid solution and 1/4 solid/liquid ratio for 30 min contact time at 80 °C. Moreover, the optimum conditions of the ammonium sulfate preparation are 10 g of the suspended impure or purified phosphogypsum in 40 ml of 3% ammonium sulfate solution (as initiator, 1/4 solid/liquid ratio at pH7 at an addition of an excess ammonium carbonate, and 150 rpm stirring speed for 4.0 h contact time at 55 °C as well as the 5 mg of barium chloride is added to remove the radium in the ammonium sulfate product. Finally, the ammonium sulfate is crystallized and the chemical analysis of the product shows 20% nitrogen and 23.6% sulfur. Therefore, the purity of the obtained ammonium sulfate is 95% from the purified phosphogypsum.

  7. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Directory of Open Access Journals (Sweden)

    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.

  8. Fluoride Adsorption by Pumice from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Amir Hossein Mahvi

    2012-01-01

    Full Text Available Drinking water provides many vital elements for the human body, but the presence of some dissolved elements more than permissible concentration can endanger human health. Among the dissolved elements in drinking water, fluoride is noticeable, because both the very low or very high concentrations have adverse health impacts such as dental caries. Therefore, fluoride concentration should be kept in acceptable levels. In this study Pumice was used for fluoride removal. It was found that Fluoride sorption kinetic was fitted by pseudo-second-order model. The maximum sorption capacity of Pumice was found to be 13.51 mg/g at laboratory temperature (24°C. Maximum sorption study occurred at pH= 3. Results of Isotherm showed the fluoride sorption has been well fitted with Freundlich isotherm model. This study has demonstrated that Pumice can be used as effective adsorbents for fluoride removal from aqueous solutions. The adsorbent prepared in this study was cheap and efficient in removal of fluoride than other adsorbents.

  9. Current status of fluoride volatility method development

    Energy Technology Data Exchange (ETDEWEB)

    Uhlir, J.; Marecek, M.; Skarohlid, J. [UJV - Nuclear Research Institute, Research Centre Rez, CZ-250 68 Husinec - Rez 130 (Czech Republic)

    2013-07-01

    The Fluoride Volatility Method is based on a separation process, which comes out from the specific property of uranium, neptunium and plutonium to form volatile hexafluorides whereas most of fission products (mainly lanthanides) and higher transplutonium elements (americium, curium) present in irradiated fuel form nonvolatile tri-fluorides. Fluoride Volatility Method itself is based on direct fluorination of the spent fuel, but before the fluorination step, the removal of cladding material and subsequent transformation of the fuel into a powdered form with a suitable grain size have to be done. The fluorination is made with fluorine gas in a flame fluorination reactor, where the volatile fluorides (mostly UF{sub 6}) are separated from the non-volatile ones (trivalent minor actinides and majority of fission products). The subsequent operations necessary for partitioning of volatile fluorides are the condensation and evaporation of volatile fluorides, the thermal decomposition of PuF{sub 6} and the finally distillation and sorption used for the purification of uranium product. The Fluoride Volatility Method is considered to be a promising advanced pyrochemical reprocessing technology, which can mainly be used for the reprocessing of oxide spent fuels coming from future GEN IV fast reactors.

  10. Determination of the stability constant of Np(V) fluoride complex using a fluoride ion selective electrode

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, R.M.; Rizvi, G.H.; Chaudhuri, N.K.; Patil, S.K. (Bhabha Atomic Research Centre, Bombay (India). Radiochemistry Div.)

    1985-04-01

    Fluoride complexing of Np(V) was studied using fluoride ion selective electrode (F-ISE). Free fluoride ion concentrations in the presence of Np(V) were measured at 0.1 and 0.01M ionic strength. The data were used to calculate the stability constant of the fluoride complex of Np(V) and the values obtained are reported.

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

    Science.gov (United States)

    Suljak, J P; Hatibovic-Kofman, S

    1996-09-01

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

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

    Science.gov (United States)

    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 dental fluorosis in areas where the fluoride concentration was high.

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

    OpenAIRE

    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...

  14. Substrate specificity of Rhbg: ammonium and methyl ammonium transport.

    Science.gov (United States)

    Nakhoul, Nazih L; Abdulnour-Nakhoul, Solange M; Boulpaep, Emile L; Rabon, Edd; Schmidt, Eric; Hamm, L Lee

    2010-09-01

    Rhbg is a nonerythroid membrane glycoprotein belonging to the Rh antigen family. In the kidney, Rhbg is expressed at the basolateral membrane of intercalated cells of the distal nephron and is involved in NH4+ transport. We investigated the substrate specificity of Rhbg by comparing transport of NH3/NH4+ with that of methyl amine (hydrochloride) (MA/MA+), often used to replace NH3/NH4+, in oocytes expressing Rhbg. Methyl amine (HCl) in solution exists as neutral methyl amine (MA) in equilibrium with the protonated methyl ammonium (MA+). To assess transport, we used ion-selective microelectrodes and voltage-clamp experiments to measure NH3/NH4+- and MA/MA+-induced intracellular pH (pH(i)) changes and whole cell currents. Our data showed that in Rhbg oocytes, NH3/NH4+ caused an inward current and decrease in pH(i) consistent with electrogenic NH4+ transport. These changes were significantly larger than in H2O-injected oocytes. The NH3/NH4+-induced current was not inhibited in the presence of barium or in the absence of Na+. In Rhbg oocytes, MA/MA+ caused an inward current but an increase (rather than a decrease) in pH(i). MA/MA+ did not cause any changes in H2O-injected oocytes. The MA/MA+-induced current and pH(i) increase were saturated at higher concentrations of MA/MA+. Amiloride inhibited MA/MA+-induced current and the increase in pH(i) in oocytes expressing Rhbg but had no effect on control oocytes. These results indicate that MA/MA+ is transported by Rhbg but differently than NH3/NH4+. The protonated MA+ is likely a direct substrate whose transport resembles that of NH4+. Transport of electroneutral MA is also enhanced by expression of Rhbg.

  15. High density fluoride glass calorimeter

    Science.gov (United States)

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

    2014-04-01

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

  16. Growth, spectral, structural and mechanical properties of struvite crystal grown in presence of sodium fluoride

    Indian Academy of Sciences (India)

    K Suguna; M Thenmozhi; C Sekar

    2012-08-01

    Struvite or magnesium ammonium phosphate hexahydrate (MAP) is one of the components of urinary stone. Struvite stones are commonly found in women. It forms in human beings as a result of urinary tract infection with urea splitting organisms. These stones can grow rapidly forming “staghorn-calculi”, which is a painful urological disorder. Therefore, it is of prime importance to study the growth and inhibition of struvite crystals. The growth inhibition effect of struvite crystals in sodium metasilicate (SMS) gel in the presence of sodium fluoride has been carried out. Crystals obtained have been analysed by powder and single crystal XRD, SEM–EDX, FTIR and TG–DTA. The results show that the presence of fluoride significantly affects struvite crystal growth and the characteristics of the crystallites produced. The mechanical property of the grown crystals has been investigated by Vickers microhardness testing. Work hardening coefficient was found to be >1.6 for both pure and doped samples which suggests that the crystal belongs to the family of soft material. Presence of sodium fluoride further softened the crystal.

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

    Science.gov (United States)

    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 (pdental 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.

  18. Materials processing apparatus development for fluoride glass

    Science.gov (United States)

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

    1994-01-01

    Fluoride glasses have great potential for optical fiber communications due to the high transmittance when no microcrystallites occur during drawing operations. This work has developed apparatus to test the occurrence of microcrystallites during recrystallization in reduced gravity on the KC-135. The apparatus allows fluoride glass fiber, such as ZBLAN, to be melted and recrystallized during both the low and high g portions the parabolic flight.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Attar, Nuray; Turgut, Melek D

    2003-01-01

    Many fluoride-releasing dental materials are being sold on the basis of their cariostatic properties. However, the amount fluoride release of these materials is still uncertain. This study investigated the fluoride release and uptake characteristics of four flowable resin composites (Heliomolar Flow, Tetric Flow, Wave, Perma Flo), one flowable compomer (Dyract flow), one conventional glass ionomer cement mixed with two different powder/liquid ratios (ChemFlex Syringeable and ChemFlex Condensable), one packable resin composite (SureFil), one ion-releasing composite (Ariston pHc) and one resin-modified glass ionomer cement (Vitremer). Seven discs (6-mm diameter and 1.5-mm height) were prepared for each material. Each disc was immersed in 3.5 ml of deionized water within a plastic vial and stored at 37 degrees C. The deionized water was changed every 24 hours and the release of fluoride was measured for 30 days. At the end of this period, the samples were recharged with 2 ml of 1.23% acidulated phosphate fluoride (APF) gel for four minutes. Then, all samples were reassessed for an additional 10 days. The fluoride release of all samples was measured with a specific fluoride electrode and an ionanalyzer. Statistical analyses were conducted using two-way repeated measure ANOVA and Duncan's multiple range tests. For all tested materials, the greatest fluoride release was observed after the first day of the study (p0.05). Ariston pHc released the highest amount of fluoride, followed by ChemFlex Syringeable, Vitremer and ChemFlex Condensable. There were statistically significant differences among these materials (p<0.05). Fluoride release of all materials were significantly increased after the first day following refluoridation and Ariston pHc released the greatest among all materials (p<0.01). At the end of two days of refluoridation, the fluoride release rate for each material dropped quickly and stabilized within three days.

  1. Well Waters Fluoride in Enugu, Nigeria

    Directory of Open Access Journals (Sweden)

    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.

  2. Analysis of fluoride concentration in solutions prepared at dispensing pharmacies

    Directory of Open Access Journals (Sweden)

    Eduardo Pizzatto

    2011-07-01

    Full Text Available Introduction: Fluoride plays an important role in oral health promotion and is considered important in dental caries prevention both in children and adults. Fluoride is widely used at high-risk conditions of caries, when the use of fluoride-containing mouthwashes is recommended, considering that fluoride itself reduces the risk of dental caries. Objective: To evaluate the fluoride concentration in solutions prepared at different dispensing pharmacies in the city of Curitiba – PR, Brazil. Material and methods: The analysis of fluoride concentration was preformed through Ion Chromatography method (DIONEX. Results: The results obtained through this analysis showed that all solutions presented fluoride concentration above that required in the dentist’s prescription, varying between 5.48% and 24.02% more fluoride, at absolute concentration. Conclusion: This finding highlights the increasing risk of fluoride acute intoxication in cases of accidental ingestion of the solution.

  3. 77 FR 65532 - Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation: Notice of Rescission of...

    Science.gov (United States)

    2012-10-29

    ... International Trade Administration Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation: Notice... the antidumping duty order on solid fertilizer grade ammonium nitrate (ammonium nitrate) from the... Administrative Review: Solid Fertilizer Grade Ammonium Nitrate (Ammonium Nitrate) from the Russian...

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2000-03-01

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

  6. Plaque formation and lactic acid production after use of amine fluoride/stannous fluoride mouthrinse

    NARCIS (Netherlands)

    Gerardu, V.A.M.; Buijs, M.; Loveren, C. van; Cate, J.M. ten

    2007-01-01

    The aim of this study was lo determine the effects of 3 wk of daily rinsing with amine fluoride/stannous fluoride (AmF/SnF2) mouthrinse on plaque formation at buccal and interproximal sites, and on the acid production in plaque. in a randomized clinical trial with 30 participants. The amount of plaq

  7. Cancer incidence and mortality in workers exposed to fluoride

    DEFF Research Database (Denmark)

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

    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-exposed wor......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...

  8. Influence of the method of fluoride administration on toxicity and fluoride concentrations in Japanese quail

    Science.gov (United States)

    Fleming, W.J.; Schuler, C.A.

    1988-01-01

    Young Japanese quail (Coturnix japonica) were administered NaF for 16 d either in their diet or by esophageal intubation. Based on the total fluoride ion (Emg F-) intake over the l6-d experimental period, fluoride administered by intubation was at least six times more toxic than that fed in the diet. Dietary concentrations of 1,000 ppm F- (Emg F- for 16 d = approx. 144) produced no mortality, whereas intubated doses produced 73% or greater mortality in all groups administered 54 mg F- /kg/d or more (Emg F- for 16 d _ approx. 23 mg). GraphIc companson of the regression of log F- ppm in femurs/mg F- intake showed that fluoride levels in the femurs of quail administered fluoride by intubation were higher than in those administered fluoride in the diet.

  9. Natural Nitrogen—15 Abundance of Ammonium Nitrogen and Fixed Ammonium in Soils

    Institute of Scientific and Technical Information of China (English)

    SHISHU-LIAN; XINGGUANG-XI; 等

    1992-01-01

    The present article deals with the natural nitrogen-15 abundance of ammonium nitrogen and fixed ammonium in different soils.Variations in the natural 15N abundance of ammonium nitrogen mineralized in soils under anaerobic incubation condition were related to soil pH.The δ 15N of mineralizable N in acid soils was lower but that in neutral and calcareous soils was higher compared with the δ 15N of total N in the soils.A variation tendence was also found in the δ 15N of amino-acid N in the hydrolysates of soils.The natural 15N abundance of fixed ammonium was higher than that of total N in most surface soils and other soil horizons,indicating that the increase of δ 15N in the soil borizons beneath subsurface horizon of some forest soils and acid paddy soils was related to the higher δ 15N value of fixed ammonium in the soil.

  10. Calcium sulphate in ammonium sulphate solution

    Science.gov (United States)

    Sullivan, E.C.

    1905-01-01

    Calcium sulphate, at 25?? C., is two-thirds as soluble in dilute (o.i mol per liter) and twice as soluble in concentrated (3 mois per liter) ammonium sulphate solution as in water. The specific electric conductivity of concentrated ammonium sulphate solutions is lessened by saturating with calcium sulphate. Assuming that dissociation of ammonium sulphate takes place into 2NH4?? and SO4" and of calcium sulphate into Ca and SO4" only, and that the conductivity is a measure of such dissociation, the solubility of calcium sulphate in dilute ammonium sulphate solutions is greater than required by the mass-law. The conductivity of the dilute mixtures may be accurately calculated by means of Arrhenius' principle of isohydric solutions. In the data obtained in these calculations, the concentration of non-dissociated calcium sulphate decreases with increasing ammonium sulphate. The work as a whole is additional evidence of the fact that we are not yet in possession of all the factors necessary for reconciling the mass-law to the behavior of electrolytes. The measurements above described were made in the chemical laboratory of the University of Michigan.

  11. Reduction in Ammonium Ions in Sludge Liquor

    Directory of Open Access Journals (Sweden)

    Eglė Šlajūtė

    2013-12-01

    Full Text Available Liquor rejected from the centrifugation of the digested sludge can contain the concentrations of ammonium ions up to 1750 mg/L. These loads are usually returned to the intake of wastewater treatment plants (WWTP without additional treatment and can have a negative impact on biological wastewater and/or sludge treatment processes, e.g. phosphorus and nitrogen removal. This article deals with the use of naturally obtained sorbent, zeolite, in batch and column test procedure for removing ammonium from the rejected liquor. This research study was carried out using different sizes of zeolite particles: 0.8–1.6 mm and 1.6–2.5 mm. The highest efficiency of ammonium removal (up to 98 % was achieved by applying the zeolite particles of 0.8–1.6 mm.Article in Lithuanian

  12. Thermodynamic data-base for metal fluorides

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruël, Bianca H.M.; Engbersen, Johan F.J.; Reinhoudt, David N.

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  14. On the evaporation of ammonium sulfate solution

    Energy Technology Data Exchange (ETDEWEB)

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-07-16

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yu Xudong, E-mail: 081022009@fudan.edu.cn [College of Science, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Li Yajuan [College of Science, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Yin Yaobing; Yu Decai [College of Science, Hebei University of Engineering, 199 South street of Guangming, Handan 056038 (China)

    2012-08-01

    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 {sup 1}HNMR (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{sup -} 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: Black-Right-Pointing-Pointer A novel kind receptor for selective recognition of fluoride had been designed. Black-Right-Pointing-Pointer Its organogel was also fluoride-responsive. Black-Right-Pointing-Pointer This is the simplest fluoride-responsive organogel with high selectivity.

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

    Science.gov (United States)

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

    2013-11-01

    The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF) rather than levels of bioavailable fluoride (total soluble fluoride-TSF) in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80) or children's toothpaste (n = 78)). The estimated dose (mg F/day/Kg of body weight) of TF or TSF ingested was calculated from the chemical analysis of the toothpastes. Although the ingested dose of TF from the family toothpastes was higher than that from the children's toothpastes (0.074 ± 0.007 and 0.039 ± 0.003 mg F/day/Kg, respectively; p toothpaste was found regarding the ingested dose based on TSF (0.039 ± 0.005 and 0.039 ± 0.005 mg F/day/Kg, respectively; p > 0.05). The fluoride dose ingested by children from toothpastes may be overestimated if based on the TF of the product. This finding suggests that the ingested dose should be calculated based on TSF. Dose of TSF ingested by children is similar whether family or children's toothpaste is used.

  17. Vitrification of strontium-90 fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Strachan, D.M.; Schulz, W.W.

    1977-04-01

    At Hanford, strontium-90 is removed from high-level nuclear fuel reprocessing waste and converted to strontium-90 fluoride. This /sup 90/SrF/sub 2/ is doubly encapsulated in high-integrity containers which are placed under water in monitored storage pools. Conversion of /sup 90/SrF/sub 2/ to a more immobile compound may be necessary and/or desirable as part of the overall plan for the long-term management of Hanford Defense Wastes. Glasses containing up to 40 mass percent SrF/sub 2/ and having leach rates in the range 1 x 10/sup -8/ to 1 x 10/sup -5/ gram Sr/(m/sup 2/ . s) (1 x 10/sup -7/ to 1 x 10/sup -4/ g Sr/cm/sup 2/ . day)) have now been prepared. From 0.2 to 5 percent of the fluorine is volatilized during the melting of the glass batch at temperatures up to 1500/sup 0/K. At present, the heat generation limit for commercial glasses stored at a nuclear waste repository is 5 kW per canister. All glasses described here would exceed that limit by more than a factor of five. The stored /sup 90/SrF/sub 2/ may be treated separately from the bulk of Hanford waste, in which case it would be diluted to an acceptable power level with inert chemicals in the glass batch. Another option is to blend the /sup 90/SrF/sub 2/ with the bulk of the other Hanford wastes when those wastes are converted to some immobile form.

  18. Uses of sodium fluoride varnish in dental practice.

    Science.gov (United States)

    Chu, C H; Lo, Edward

    2008-06-01

    Fluoride varnish is developed to prolong the contact time between fluoride and tooth surface, so that the tooth becomes more resistant to caries attack. The active ingredient of fluoride varnish is usually 5% sodium fluoride, (22,600 ppm fluoride). Studies have found that fairly insoluble globules of calcium fluoride-like material formed on the tooth surface after topical fluoride application. These globules act as a reservoir of fluoride in the mouth for a prolonged period of time. Systematic reviews corroborate evidence for the efficacy of fluoride varnish in the prevention of dental caries. Sodium fluoride varnish is used to prevent caries development, arrest early enamel and even soft dentine caries through promotion of remineralization of carious tooth substance. It is also used to treat tooth hypersensitivity. Some use it as a provisional luting agent by itself or combined with other provisional luting agents for cementing provisional crowns. Fluoride varnish has recently gained much attention in dentistry because it is quick and easy to apply. It sets rapidly on teeth, and gagging and swallowing is unusual. Side-effects or complications of its use are rare. Studies show that fluoride varnish is safe for young children and the risk of dental fluorosis is minimal. The simplicity of its application makes it very suitable and practical for use in dental clinics and outreach dental services, especially in young children and in other special needs groups.

  19. 21 CFR 177.2510 - Polyvinylidene fluoride resins.

    Science.gov (United States)

    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...

  20. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Science.gov (United States)

    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) resins identified in this section may be safely used as components of food-contact coatings...

  1. Health effects of fluoride pollution caused by coal burning

    Energy Technology Data Exchange (ETDEWEB)

    Ando, M.; Tadano, M.; Yamamoto, S.; Tamura, K.; Chen, X. [Regional Environment Division, National Institute for Environmental Studies, Tsukuba, 305-0083 Ibaraki (Japan); Asanuma, S. [Japan Institute of Rural Medicine, Usuda, Nagano (Japan); Watanabe, T. [Saku Central Hospital, Usuda, Nagano (Japan); Kondo, T. [Matsumoto Dental College, Shiojiri, Nagano (Japan); Sakurai, S. [Otsuma Women' s University, Tama, Tokyo (Japan); Ji, R.; Liang, C.; Cao, S. [Institute of Environmental Health and Engineering, Beijing (China); Hong, Z. [Shanxi Maternity and Children' s Hospital, Taiyuan (China)

    2001-04-23

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

  2. Enhanced fluoride sorption by mechanochemically activated kaolinites.

    Science.gov (United States)

    Meenakshi, S; Sundaram, C Sairam; Sukumar, Rugmini

    2008-05-01

    Kaolinite clay obtained from the mines was processed and studied for its fluoride sorption capacity. The surface area of the clay mineral was increased from 15.11 m(2)/g (raw) to 32.43 m(2)/g (activated) by mechanochemical activation. Batch adsorption studies were conducted to optimize various equilibrating conditions like the effect of contact time, dosage, pH for both raw and micronized kaolinites (RK and MK). The effect of other interfering anions on the defluoridation capacity (DC) of the sorbents was studied. Sorption of fluoride by the sorbents was observed over a wide pH range of 3-11. The studies revealed there is an enhanced fluoride sorption on MK. FTIR and XRD were used for the characterization of the sorbent. The surface morphology of the clay material was observed using SEM. The adsorption of fluoride was studied at three different temperatures, viz., 303, 313 and 323 K. The sorption data obtained at optimized conditions were subjected to Freundlich and Langmuir isotherms. Sorption intensity (1/n) (0.770-0.810) has been evaluated using Freundlich isotherm, whereas the values of sorption capacity Q(0) (0.609, 0.714 and 0.782 mg/g) and binding energy b (0.158, 0.145 and 0.133 L/mg) at three different temperatures have been estimated using Langmuir isotherm. Adsorption process was found to be controlled by both Freundlich and Langmuir isotherms. Thermodynamic studies revealed that the sorption of fluoride on MK is endothermic and a spontaneous process. The kinetic studies indicate that the sorption of fluoride on MK follows pseudo-first-order and intraparticle diffusion models.

  3. Enhanced fluoride sorption by mechanochemically activated kaolinites

    Energy Technology Data Exchange (ETDEWEB)

    Meenakshi, S. [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Tamilnadu (India)], E-mail: drs_meena@rediffmail.com; Sundaram, C. Sairam [Department of Science and Humanities, Karaikal Polytechnic College, Karaikal 609609, Puducherry (India); Sukumar, Rugmini [Chemical Sciences and Technologies, Regional Research Laboratory, Trivandrum 695019, Kerala (India)

    2008-05-01

    Kaolinite clay obtained from the mines was processed and studied for its fluoride sorption capacity. The surface area of the clay mineral was increased from 15.11 m{sup 2}/g (raw) to 32.43 m{sup 2}/g (activated) by mechanochemical activation. Batch adsorption studies were conducted to optimize various equilibrating conditions like the effect of contact time, dosage, pH for both raw and micronized kaolinites (RK and MK). The effect of other interfering anions on the defluoridation capacity (DC) of the sorbents was studied. Sorption of fluoride by the sorbents was observed over a wide pH range of 3-11. The studies revealed there is an enhanced fluoride sorption on MK. FTIR and XRD were used for the characterization of the sorbent. The surface morphology of the clay material was observed using SEM. The adsorption of fluoride was studied at three different temperatures, viz., 303, 313 and 323 K. The sorption data obtained at optimized conditions were subjected to Freundlich and Langmuir isotherms. Sorption intensity (1/n) (0.770-0.810) has been evaluated using Freundlich isotherm, whereas the values of sorption capacity Q{sup 0} (0.609, 0.714 and 0.782 mg/g) and binding energy b (0.158, 0.145 and 0.133 L/mg) at three different temperatures have been estimated using Langmuir isotherm. Adsorption process was found to be controlled by both Freundlich and Langmuir isotherms. Thermodynamic studies revealed that the sorption of fluoride on MK is endothermic and a spontaneous process. The kinetic studies indicate that the sorption of fluoride on MK follows pseudo-first-order and intraparticle diffusion models.

  4. Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique

    Energy Technology Data Exchange (ETDEWEB)

    Mohapatra, M., E-mail: mamatamohapatra@yahoo.com [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Rout, K. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Singh, P. [Murdoch University, Perth, Western Australia (Australia); Anand, S. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India); Layek, S.; Verma, H.C. [Indian Institute of Technology, Kanpur (India); Mishra, B.K. [Institute of Minerals and Materials Technology, Acharyavihar, Bhubaneswar 751 013, Orissa (India)

    2011-02-28

    Mixed nano iron oxides powder containing goethite ({alpha}-FeOOH), hematite ({alpha}-Fe{sub 2}O{sub 3}) and ferrihydrite (Fe{sub 5}HO{sub 8}.4H{sub 2}O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, Moessbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55 deg. C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO{sub 4}{sup 2-} or Cl{sup -} adversely affected the adsorption of fluoride in the order of SO{sub 4}{sup 2-} > Cl{sup -}. The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. Moessbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%.

  5. Effects of Aromatic Ammoniums on Methyl Ammonium Lead Iodide Hybrid Perovskite Materials

    Directory of Open Access Journals (Sweden)

    Jianli Yang

    2017-01-01

    Full Text Available The introduction of bulky ammoniums into methyl ammonium lead iodide hybrid perovskites (MAPbI3 has emerged as a promising strategy to improve the properties of these materials. In the present work, we studied the effects of several aromatic ammoniums onto the structural, electronic, and optical properties of MAPbI3. Although powder XRD data suggest that the bulky cations are not involved in the bulk phase of the MAPbI3, a surprisingly large effect of the bulky cations onto the photoluminescence properties was observed.

  6. Review of Ammonium Dinitramide Toxicity Studies

    Science.gov (United States)

    2011-01-01

    reproductive toxicant in rats, causing implantation failure in early gestation; follow-on studies implied that ADN is embryotoxic . EPR studies indicated that...mutagenic. 15. SUBJECT TERMS Ammonium dinitramide, ADN, toxicity, reproductive, embryotoxic , genotoxicity 16. SECURITY CLASSIFICATION OF: U 17...reproductive studies, reproduction and fertility, pre-implantation and post-implantation studies, implied that ADN is embryotoxic . A mouse embryo

  7. Detonation characteristics of ammonium nitrate products

    NARCIS (Netherlands)

    Kersten, R.J.A.; Hengel, E.I.V. van den; Steen, A.C. van der

    2006-01-01

    The detonation properties of ammonium nitrate (AN) products depend on many factors and are therefore, despite the large amount of information on this topic, difficult to assess. In order to further improve the understanding of the safety properties of AN, the European Fertilizer Manufacturers Associ

  8. Synthesis of complex fluorides for optical applications

    Science.gov (United States)

    Stepleton, Seth Eugene

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

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Fluoride in Drinking Water -Its Effects and Removal

    Directory of Open Access Journals (Sweden)

    Ram Gopal

    1985-01-01

    Full Text Available Occurrence of fluoride in water, its metabolism, excretion. effect oingestion in human and cattle system and methods of fluoridation and defluoridation have been discussed. The presence of fluoride in waters occurring in India, with special reference to Rajasthan desert has been reviewed. Based on the survey and physico-chemical analyses of about 2,700 water samples of Rajasthan, distribution of fluoride in this area has been discussed wrth reference to drinking water standards. A water resources map showing concentrations of fluoride in four arid districts of Rajasthan is also presented.

  11. Multicolor tunability and upconversion enhancement of fluoride nanoparticles by oxygen dopant

    Science.gov (United States)

    Niu, Wenbin; Wu, Suli; Zhang, Shufen; Su, Liap Tat; Tok, Alfred Iing Yoong

    2013-08-01

    The ability to manipulate the upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is particularly important and highly desired due to their wide applications in color displays, multiplexing bioassays and multicolor imaging. Here, we developed a strategy for simultaneously tuning color output and enhancing upconversion emission of Yb/Er doped fluoride UCNPs, based on adjusting the oxygen doping level. The synthesis of multicolored multifunctional NaGdF4:Yb,Er UCNPs was used as the model host system to demonstrate this protocol. Ammonium nitrate (NH4NO3) was used as the oxygen source and added into the reaction system at the beginning stage of nucleation and growth process of fluoride UCNPs, which facilitates the formation of enough oxygen atoms and the diffusion of these into the fluoride host matrix. The results revealed that multicolour output and upconversion enhancement mainly resulted from the variation of phonon energy and crystal field symmetry of the host lattice, respectively. This strategy can be further expanded to other fluoride host matrices. As an example of an application, multicolored UCNPs were used as a color converter in light emitting diodes, which can effectively convert near-infrared light into visible light. It is expected that these multicolored UCNPs will be promising for applications in multiplexing biodetection, bioimaging (optical and magnetic resonance imaging) and other optical technologies, and the present method for the control of O2- doping may also be used in other functional nanomaterials.The ability to manipulate the upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is particularly important and highly desired due to their wide applications in color displays, multiplexing bioassays and multicolor imaging. Here, we developed a strategy for simultaneously tuning color output and enhancing upconversion emission of Yb/Er doped fluoride UCNPs, based

  12. ANALYSIS ON INFLUENCE REGULARITY OF THE AMMONIA-AMMONIUM LEACHING SYSTEM ON LEACHING RATE OF COPPER%不同氨-铵浸出体系对氧化铜矿铜浸出率影响规律的研究

    Institute of Scientific and Technical Information of China (English)

    毛莹博; 方建军; 文娅; 赵文娟; 王珊; 魏志聪

    2012-01-01

    In this paper, through a series of experiment studies about the different ammonia-ammonium coupling of leaching system for the effect of copper oxide ore leaching, a significant influence sequence of the different ammonia-ammonium coupling of leaching system on the leaching rate of copper is determined as following : ammonia-ammonium carbamate > ammonia-ammonium carbonate > ammonia-ammonium chloride > ammonia-ammonium fluoride > ammonia-ammonium bicarbonate > ammonia-ammonium sulfate. The ammonia-ammonium carbamate leaching system is adopted as the experiment study of high calcium and magnesium, low grade and argillaceous copper oxide ore in Xinjiang Water, and the copper leaching rate is as high as 85. 25% .%通过不同氨-铵浸出体系对氧化铜矿浸出影响的试验研究,确定了不同氨-铵浸出体系对铜浸出率的显著性影响顺序是:氨-氨基甲酸铵>氨-碳酸铵>氨-氯化铵>氨-氟化铵>氨-碳酸氢铵>氨-硫酸铵.采用氨-氨基甲酸铵浸出体系对新疆滴水高钙镁低品位泥质氧化铜矿进行浸出试验,铜浸出率高达85.25%.

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

    Science.gov (United States)

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

    2013-11-01

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

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

    Directory of Open Access Journals (Sweden)

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

    Science.gov (United States)

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

    1984-01-01

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

  16. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    Science.gov (United States)

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

    2016-01-01

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

  17. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    Directory of Open Access Journals (Sweden)

    Stefano Dugheri

    2016-01-01

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

  18. Oral fluoride retention after professional topical application in children with caries activity: comparison between 1.23% fluoride foam and fluoride gel

    Directory of Open Access Journals (Sweden)

    Cecília Claudia Costa Ribeiro

    2008-01-01

    Full Text Available Objective: This study evaluated fluoride retention in the saliva of children with caries activity after topical fluoride application in the form of gel and foam. Methods: A cross-sectional, blind and randomized study, conducted with ten caries-active children aged between 8 and 10 years, in two stage, with a washout interval of two weeks between them. The treatments consisted of: a application of 2mL acidulated phosphate fluoride of the gel type in a mold and b application of 2mL acidulated phosphate fluoride of the foam type in a mold. After the washout, the treatments were inverted. Non-stimulated saliva was collected from the children at the times of 5, 15, 30 and 60 minutes after topical fluoride application. For statistical analysis the Student’s-t test was used, with a level of significance of 5%. Results: Saliva analysis was performed using a fluoride-specific electrode (ISE25F/ Radiometer, Copenhagen, Denmark at the Aquatic Science Center of the Federal University of Marana, which revealed differences after 5 minutes (p=0.0055 and 15 minutes (p=0.0208. The topical application of fluoride in the gel form revealed a higher concentration of fluoride in the saliva. Conclusion: There were differences in the retention of fluoride in the saliva of children with caries activity after the topical application of fluoride gel and the topical application of fluoride foam after 5 and 15 minutes of their application. The topical application of fluoride foam is recommended, on the basis of the lower probability of toxicity during its use.

  19. 21 CFR 184.1141b - Ammonium phosphate, dibasic.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium phosphate, dibasic. 184.1141b Section 184... Listing of Specific Substances Affirmed as GRAS § 184.1141b Ammonium phosphate, dibasic. (a) Ammonium phosphate, dibasic ((NH4)2HPO4, CAS Reg. No. 7783-28-0) is manufactured by reacting ammonia with...

  20. 21 CFR 172.165 - Quaternary ammonium chloride combination.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Quaternary ammonium chloride combination. 172.165... HUMAN CONSUMPTION Food Preservatives § 172.165 Quaternary ammonium chloride combination. The food additive, quaternary ammonium chloride combination, may be safely used in food in accordance with...

  1. 78 FR 32690 - Certain Ammonium Nitrate From Ukraine

    Science.gov (United States)

    2013-05-31

    ... COMMISSION Certain Ammonium Nitrate From Ukraine Determination On the basis of the record \\1\\ developed in... antidumping duty order on certain ammonium nitrate from Ukraine would be likely to lead to continuation or... Publication 4396 (May 2013), entitled Certain Ammonium Nitrate from Ukraine: Investigation No....

  2. 21 CFR 184.1296 - Ferric ammonium citrate.

    Science.gov (United States)

    2010-04-01

    ... citrate (iron (III) ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid, followed by treatment with ammonium hydroxide, evaporating, and drying. The resulting product occurs in two forms depending on the stoichiometry of the initial reactants. (1) Ferric ammonium citrate (iron...

  3. Effects of fluoridated milk on root dentin remineralization.

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Quaternary ammonium compounds – New occupational hazards

    Directory of Open Access Journals (Sweden)

    Agnieszka Lipińska-Ojrzanowska

    2014-10-01

    Full Text Available Quaternary ammonium compounds (QACs, quats belong to organic ionic chemical agents which display unique properties of both surfactants and disinfectants. Their wide distribution in the work environment and also in private households brings about new occupational hazards. This paper reviews reports about the health effects of QACs. QACs could play a role of sensitizers and irritants to the skin and mucous membranes. It is suspected that particular QACs can display an immunologic crossreactivity between each other and with other chemical compounds containing ammonium ion, such as muscle relaxants widely used in anesthesia. They may promote the development of airway allergy, however, the background mechanisms are still unclear and need to be further investigated. Until now, a few cases of occupational asthma induced by QACs have been described and their involvement in contact dermatitis has been documented. The possibility of anaphylaxis due to QACs cannot be excluded as well. Med Pr 2014;65(5:675–682

  7. Detonation Properties of Ammonium Dinitramide (ADN)

    Science.gov (United States)

    Wätterstam, A.; Östmark, H.; Helte, A.; Karlsson, S.

    1999-06-01

    Ammonium Dinitramide, ADN, has a potential as an oxidizer for underwater high explosives. Pure ADN has a large reaction-zone length and shows a strong non-ideal behaviour. The work presented here is an extension of previous work.(Sensitivity and Performance Characterization of Ammonium Dinitramide (ADN). Presented at 11th International Detonation Symposium, Snowmass, CO, 1998.) Experiments for determining the detonation velocity as a function of inverse charge radius and density, reaction-zone length and curvature, and the detonation pressure are presented. Measurements of pressure indicates that no, or weak von-Neumann spike exists, suggesting an immediate chemical decomposition. Experimental data are compared with predicted using thermochemical codes and ZND-theory.

  8. Effects of long term exposure to hydrogen fluoride on grapevines

    Energy Technology Data Exchange (ETDEWEB)

    Murray, F.

    1984-01-01

    Grapevines Vitis vinifera L. Shiraz were exposed to hydrogen fluoride in open-top chambers for 189 days at mean atmospheric fluoride concentrations of 0.27, 0.17 or 0.07 ..mu..g HFm/sup -3/. Grapevines growing under ambient conditions outside the chambers were exposed to a mean atmospheric fluoride concentration of 0.08 ..mu..g HFm/sup -3/. The maximum leaf fluoride concentrations associated with these treatments were 62, 27, 9 and 15 ..mu..g Fg/sup -1/, respectively. Foliar necrosis was first observed on grapevines exposed to 0.27 and 0.17 ..mu..g HFm/sup -3/ after 83 and 99 days, respectively. Exposure to fluoride increased the fluoride content of berries and peduncles, and reduced leaf chlorophyll a and total chlorophyll concentration at both mid-season and harvest. Exposure to 0.17 ..mu..g HF m/sup -3/ was associated with higher total acid content of grapes than other treatments. Fluoride had no significant effect on bunch weight, number of bunches, grape yield, grape water or potential alcohol content, leaf chlorophyll b or leaf protein concentration. The high accumulation of fluoride in peduncles, but low fluoride accumulation in berries, suggests that the peduncle acts to block the translocation of fluoride from sites of uptake to the fruit. 42 references, 1 figure, 5 tables.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-04-01

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

  11. Parabens do not increase fluoride uptake by dental enamel

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  13. Fluoride ion encapsulation by Mg[superscript 2+] ions and phosphates in a fluoride riboswitch

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Aiming; Rajashankar, Kanagalaghatta R.; Patel, Dinshaw J. (Cornell); (MSKCC)

    2012-06-26

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A {sm_bullet} U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg{sup 2+} ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.

  14. Fluoride ion encapsulation by Mg2+ ions and phosphates in a fluoride riboswitch.

    Science.gov (United States)

    Ren, Aiming; Rajashankar, Kanagalaghatta R; Patel, Dinshaw J

    2012-05-13

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A•U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg(2+) ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.

  15. Mechanochemical synthesis, structure, and properties of solid solutions of alkaline earth metal fluorides: Ma1-xMbxF2 (M: Ca, Sr, Ba)

    Science.gov (United States)

    Heise, M.; Scholz, G.; Düvel, A.; Heitjans, P.; Kemnitz, E.

    2016-10-01

    The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides Ma1-xMbxF2 (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca1-xSrxF2 and Ba1-xSrxF2 samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and 19F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of 19F chemical shifts with the superposition model along with probability calculations for the intensity of the individual 19F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F- ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Revisiting the thermochemistry of chlorine fluorides

    CERN Document Server

    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.

  18. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    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.

  19. Fluoride complexation of element 104, rutherfordium.

    Science.gov (United States)

    Haba, Hiromitsu; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Nishinaka, Ichiro; Hirata, Masaru; Yaita, Tsuyoshi; Ichikawa, Shin-Ichi; Nagame, Yuichiro; Yasuda, Ken-Ichiro; Miyamoto, Yutaka; Kaneko, Tetsuya; Goto, Shin-Ichi; Ono, Sawako; Hirai, Toshiyuki; Kudo, Hisaaki; Shigekawa, Mitsuru; Shinohara, Atsushi; Oura, Yasuji; Nakahara, Hiromichi; Sueki, Keisuke; Kikunaga, Hidetoshi; Kinoshita, Norikazu; Tsuruga, Naoya; Yokoyama, Akihiko; Sakama, Minoru; Enomoto, Shuich; Schädel, Matthias; Brüchle, Willy; Kratz, Jens V

    2004-04-28

    Fluoride complexation of element 104, rutherfordium (Rf), produced in the 248Cm(18O,5n)261Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchange chromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the 18O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effects on the fluoride complexation of Rf.

  20. Necessity to review the Brazilian regulation about fluoride toothpastes.

    Science.gov (United States)

    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.

  1. Bone fluoride concentrations in beluga whales from Canada.

    Science.gov (United States)

    Mikaelian, I; Qualls, C W; De Guise, S; Whaley, M W; Martineau, D

    1999-04-01

    Beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary have been reported to have dental and bone abnormalities. To determine whether these lesions could be caused by high exposure to fluorides, we measured bone fluoride levels in eight beluga whales stranded on the shores of the St. Lawrence Estuary (Quebec, Canada), and in nine beluga whales killed by Inuit hunters in the Hudson Bay (North Western Territories, Canada). In both groups, fluoride concentrations were higher than those found in terrestrial mammals intoxicated by fluorides. Unexpectedly, fluoride concentration was significantly higher in beluga whales from the Hudson Bay (mean +/- SD: 10.365 +/- 1.098 ppm) than in beluga whales from the St. Lawrence Estuary (4.539 +/- 875 ppm) and was positively correlated with age in the latter population. Differences in diet might explain the differences in fluoride concentrations found between these two populations.

  2. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

    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. Fluoride contamination in rain water of Sigrauli region

    Energy Technology Data Exchange (ETDEWEB)

    Chaurasia, S.; Mishra, S.K. [Mahatma Gandhi Chitrakoot Gramodaya, Chitrakoot (India)

    2007-07-01

    In this paper fluoride was monitored in rain water during rainy season at seven locations of Sigrauli region in 2004. The sampling location covered the impact of industrial complex of the area, and its impact on surface water sources monitored for the fluoride, pH, and electrical conductivity. The higher concentration of fluoride in rain water was observed 2.03 mg/L at Dudhar and in ponds water highest value was 3.14 mg/L. This suggested that serious fluoride pollution is occurring in Singrauli region posing a threat to the health and livelihood of the people of the region. Fluoride transported by the air route from coal burning emissions of large thermal power plants concentrate in small geographical area, and industries. Fluoride pollution in Singrauli area deserve intensive scientific studies and urgent attention. 2 figs., 2 tabs.

  4. Viscosity estimation for slags containing calcium fluoride

    Institute of Scientific and Technical Information of China (English)

    Qifeng Shu; Jiayun Zhang

    2005-01-01

    Based on recently published experimental data, the Riboud model was modified for viscosity estimation of the slags containing calcium fluoride. The estimated values were in good agreement with measured data. Reasonable estimation can be achieved using the modified Riboud model for mould fluxes and ESR (eletro slag remelting) slags. Especially for ESR slags, the modified Riboud model can provide much more precise values than the original Riboud model.

  5. Fluoride glasses: properties, technology and applications

    OpenAIRE

    Poulain, M.

    2010-01-01

    Heavy Metal Fluoride Glasses (HMFG) make a group of specialty glasses that require a dry processing, purity control of starting materials and specific thermal procedures. Numerous glass compositions have been identified in different chemical systems: fluorozirconates, fluoroaluminates and fluoroindates. The most commonly used HMFG is the ZBLAN fluorozirconate glass that exhibits the largest stability against devitrification. By comparison to ZBLAN the IR cut-off wavelength is shorter in AlF3-...

  6. Effect of fluoride toothpastes on enamel demineralization

    Directory of Open Access Journals (Sweden)

    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.

  7. How and when to prescribe sodium fluoride.

    Science.gov (United States)

    Shambaugh, G E

    1989-03-01

    Sodium fluoride has now been used for 24 years in an effort to slow down or arrest sensorineural hearing nerve deterioration in patients with stapedial otosclerosis or after stapedectomy, as well as in patients with pure cochlear otosclerosis. Extensive clinical experience in thousands of patients with this therapy has demonstrated its value in arresting previously progressive sensorineural hearing loss. For a long time there were those who objected to this therapy on the basis that it had not been adequately proven by double-blind, placebo-controlled studies. They have been answered by Bretlau's study in Denmark and Fisch's from Switzerland; both investigators confirmed on small groups the value of sodium fluoride by double-blind, placebo-controlled studies. Extensive research by Professor Petrovic of Strasbourg while at our tissue culture laboratory at Northwestern University demonstrated the action of sodium fluoride on bone. A nicely designed study with radioactive strontium by Linthicum, House, and Althaus demonstrated its value in promoting maturation of a spongiotic focus. Today there is no reason to hesitate in prescribing this useful, effective, and safe medication to promote maturation of otospongiotic lesions, and thus to slow down or to arrest progression in sensorineural hearing loss.

  8. Color stability of esthetic restorative material after topical fluoride application

    OpenAIRE

    2015-01-01

    AIM: Present study was conducted to compare the effect of topical fluoride agents on color change of three aesthetic restorative materials. MATERIAL AND METHODS: Restorative material used were Ketac Fill type II (GIC), Filtek Z350(Composite) and Beuttifull II (Giomer). Topical Fluorides used were Pascal (1.23% APF gel) and Fluoride Varnish (Bifluoride). 24 samples of each restorative material were prepared, which were divided into 8 each, among three groups. Treatment of Group A with APF gel,...

  9. Inhibition of dentin demineralization by fluoride in vitro.

    Science.gov (United States)

    ten Cate, J M; Damen, J J; Buijs, M J

    1998-01-01

    Compared with the knowledge accumulated on enamel-fluoride interactions, relatively little data is available regarding fluoride effects on dentin. This applies to both laboratory and clinical studies into the efficacy of fluoride schemes for the prevention of root surface caries. This study aimed to determine the effects of fluoride and pH on the demineralization of dentin, such as to provide information necessary to develop preventive programmes. Bovine dentin blocks were subjected to undersaturated calcium- and phosphate-containing solutions in the pH range 4.0-6.0 with fluoride added at concentrations between 0.5 and 10 ppm. Non-fluoride solutions served as controls. Mineral loss was assessed chemically and by transversal microradiography. Comparisons were made with similar studies on enamel demineralization. The results showed that demineralization of dentin depends on both pH and fluoride concentration in the demineralizing solution. Inhibition of demineralization that could be relevant from a clinical point of view was found at fluoride values 5-10 times the corresponding values for enamel. Also rapid depletion of fluoride from the solutions was observed, indicating the high uptake capacity of dentin for fluoride. Lesion depth depended on pH of the solution while the fluoride levels were associated with the surface layer, both in mineral content and depth. For dentin we propose a demineralization mechanism where acid penetrates rapidly into the tissue, presumably through the tubules, after which the released calcium and phosphate is partly trapped by the inward diffusing fluoride. This leads to the formation of a surface layer, which may even be hypermineralized compared to sound dentin.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, R.M.; Chaudhuri, N.K.; Rizvi, G.H.; Patil, S.K.

    1985-08-01

    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 could 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). 18 refs.; 3 figs.; 9 tables.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-09-01

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

  12. Fluoride content in caffeinated, decaffeinated and herbal teas.

    Science.gov (United States)

    Chan, J T; Koh, S H

    1996-01-01

    The fluoride contents of infusions prepared from 44 different brands and types of teas were measured. Fluoride concentrations ranged from 0.34 to 3.71 ppm (mean = 1.50 ppm) in caffeinated tea infusions, 0.02-0.14 ppm (mean = 0.05 ppm) in herbal tea infusions, and 1.01-5.20 ppm (mean = 3.19) in decaffeinated tea infusions. This is the first report of the fluoride content of decaffeinated teas. The mean fluoride content of decaffeinated tea infusions is significantly (p decaffeination is the most likely explanation of the above observation.

  13. LiFePO_4/C via fluoride doping

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Non-stoichiometric compound fluoride-doped LiFePO4/C cathode materials were synthesized via solid-state reaction using MgF2 and AlF3 as dopant. The fluoride-doped LiFePO4/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical testing. The results show that the materials are well crystallized and fluoride doping cannot change the space structure of LiFePO4. Slight amounts of Fe2O3 with no fluoride impurity were ...

  14. [Allergy caused by sodium fluoride glycerin: a case report].

    Science.gov (United States)

    Ma, Jihong

    2012-04-01

    In recent years, though more and more ulcerations of oral mucosa caused by allergy to drug occurred clinically, allergy to sodium fluoride glycerin is extremely rare. A case of allergy to sodium fluoride glycerin occurred in Qianfoshan Campus Hospital of Shandong University. After treatment by sodium fluoride glycerin, there was mucosal edema, a large number of red miliary granules in buccal and palatal mucosa. After 3 hours, there were swallowing difficulties, but no breathing difficulties. Next day large ulcers of oral mucosa developed. The patient was cured 7 days after treatment. Fluoride-sensitive test result was positive.

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

    Science.gov (United States)

    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.

  16. Cariostatic effect of fluoride-containing restorative materials associated with fluoride gels on root dentin

    Directory of Open Access Journals (Sweden)

    Fernanda Tavares Borges

    2010-10-01

    Full Text Available Secondary caries is still the main cause of restoration replacement, especially on the root surface OBJECTIVE: This in vitro study evaluated the cariostatic effects of fluoride-containing restorative materials associated with fluoride gels, on root dentin. MATERIALS AND METHODS: A randomized complete block design was used to test the effects of the restorative systems, fluoride regimes and the interactions among them at different distances from restoration margins. Standardized cavities were prepared on 240 bovine root specimens and randomly assigned to 15 groups of treatments (n=16. Cavities were filled with the following restorative materials: Ketac-Fil (3M-ESPE; Vitremer (3M-ESPE; Dyract/Prime & Bond NT (Dentsply; Charisma/Gluma One Bond (Heraeus Kulzer and the control, Z250/Single Bond (3M-ESPE. The specimens were subjected to a pH-cycling model designed to simulate high-caries activity. During the cycles, 1.23% acidulated phosphate fluoride, 2.0% neutral sodium fluoride or deionized/distilled water (control was applied to the specimens for 4 min. The surface Knoop microhardness test was performed before (KHNi and after (KHNf the pH cycles at 100, 200 and 300 mm from the margins. Dentin microhardness loss was represented by the difference in initial and final values (KHNi - KHNf. Data were analyzed by Friedman's and Wilcoxon's tests, ANOVA and Tukey's test (α=5%. RESULTS: The interaction of restorative systems and topical treatments was not significant (p=0.102. Dentin microhardness loss was lowest closer to the restoration. Ketac-fil presented the highest cariostatic effect. Vitremer presented a moderate effect, while Dyract and Charisma did not differ from the control, Z250. The effects of neutral and acidulated fluoride gels were similar to each other and higher than the control. CONCLUSION: Conventional and resin-modified glass ionomer cements as well as neutral and acidulated fluoride gels inhibit the progression of artificial caries

  17. Stable Ammonium Bisulfate Clusters in the Atmosphere

    Science.gov (United States)

    Vehkamäki, Hanna; Napari, Ismo; Kulmala, Markku; Noppel, Madis

    2004-09-01

    Liquid drop model based equilibrium thermodynamics predicts that in the presence of even small ammonia concentrations practically all the atmospheric sulfuric acid molecules are bound to tiny, stable ammonium-bisulfate clusters. Hitherto sulfuric acid has been believed to form hydrates with water. Thermodynamic theory predicts correctly the hydrate formation observed experimentally. Results from ab initio computer simulations contradict the thermodynamic results and also the experimental findings for cluster formation in both sulfuric acid-water and ammonia-sulfuric acid-water mixtures.

  18. Exraction and separation of CERIUM(IV)/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    OpenAIRE

    Li, Y; J. G. He; X. X. Xue; Ru, H. Q.; X. W. Huang; Yang, H.

    2014-01-01

    In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  19. Effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting dentin caries in Chinese pre-school children

    OpenAIRE

    Chu, CH; Lo, ECM; Lin, HC

    2002-01-01

    Untreated dental caries in Chinese pre-school children is common. This prospective controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries. Three hundred seventy-five children, aged 3-5 years, with carious upper anterior teeth were divided into five groups. Children in the first and second groups received annual applications of silver diamine fluoride solution (44,800 ppm F). Sodium fluoride varnish (22,600 ppm F) was applied every ...

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

    Science.gov (United States)

    Light, Truman S.; Cappuccino, Carleton C.

    1975-01-01

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

  1. Synthesis of novel quaternary ammonium surfactants containing adamantane

    Institute of Scientific and Technical Information of China (English)

    Jian Wei Guo; Xing Zhong; Hua Zhu; Li Juan Feng; Ying De Cui

    2012-01-01

    A series of novel quaternary ammonium surfactants containing adamantane were designed and synthesized from 1-adamantanecarboxylic acid.The structures of target surfactants were confirmed by 1H NMR,elements analysis and FTIR.Surface properties of these surfactants were investigated.Due to the lipophilicity of adamantane,the critical micelle concentration (CMC) and C20 values of the synthesized quaternary ammonium surfactants are lower than that of conventional quaternary ammonium surfactants.

  2. Reassimilation of ammonium in Lotus japonicus.

    Science.gov (United States)

    Betti, Marco; García-Calderón, Margarita; Pérez-Delgado, Carmen M; Credali, Alfredo; Pal'ove-Balang, Peter; Estivill, Guillermo; Repčák, Miroslav; Vega, José M; Galván, Francisco; Márquez, Antonio J

    2014-10-01

    This review summarizes the most recent results obtained in the analysis of two important metabolic pathways involved in the release of internal sources of ammonium in the model legume Lotus japonicus: photorespiratory metabolism and asparagine breakdown mediated by aparaginase (NSE). The use of photorespiratory mutants deficient in plastidic glutamine synthetase (GS2) enabled us to investigate the transcriptomics and metabolomic changes associated with photorespiratory ammonium accumulation in this plant. The results obtained indicate the existence of a coordinate regulation of genes involved in photorespiratory metabolism. Other types of evidence illustrate the multiple interconnections existing among the photorespiratory pathway and other processes such as intermediate metabolism, nodule function, and secondary metabolism in this plant, all of which are substantially affected in GS2-deficient mutants because of the impairment of the photorespiratory cycle. Finally, the importance of asparagine metabolism in L. japonicus is highlighted because of the fact that asparagine constitutes the vast majority of the reduced nitrogen translocated between different organs of this plant. The different types of NSE enzymes and genes which are present in L. japonicus are described. There is a particular focus on the most abundant K(+)-dependent LjNSE1 isoform and how TILLING mutants were used to demonstrate by reverse genetics the importance of this particular isoform in plant growth and seed production.

  3. Ammonium nitrate: a promising rocket propellant oxidizer

    Science.gov (United States)

    Oommen; Jain

    1999-06-30

    Ammonium nitrate (AN) is extensively used in the area of fertilizers and explosives. It is present as the major component in most industrial explosives. Its use as an oxidizer in the area of propellants, however, is not as extensive as in explosive compositions or gas generators. With the growing demand for environmental friendly chlorine free propellants, many attempts have been made of late to investigate oxidizers producing innocuous combustion products. AN, unlike the widely used ammonium perchlorate, produces completely ecofriendly smokeless products. Besides, it is one of the cheapest and easily available compounds. However, its use in large rocket motors is restricted due to some of its adverse characteristics like hygroscopicity, near room temperature phase transformation involving a volume change, and low burning rate (BR) and energetics. The review is an attempt to consolidate the information available on the various issues pertaining to its use as a solid propellant oxidizer. Detailed discussions on the aspects relating to phase modifications, decomposition chemistry, and BR and energetics of AN-based propellants, are presented. To make the review more comprehensive brief descriptions of the history, manufacture, safety, physical and chemical properties and various other applications of the salt are also included. Copyright 1999 Elsevier Science B.V.

  4. Scientific Opinion on Dietary Reference Values for fluoride

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Yu, Xudong; Li, Yajuan; Yin, Yaobing; Yu, Decai

    2012-08-01

    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 (1)HNMR (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.

  6. Effects of alternating periods of high- and low- fluoride ingestion on dairy cattle

    Energy Technology Data Exchange (ETDEWEB)

    Suttie, J.W.; Carlson, J.R.; Faltin, E.C.

    1972-01-01

    Two- and five-month old Holstein heifers were exposed to different intake patterns of dietary fluoride for 6 years. None of the fluoride treatments affected growth rate or reproduction. There was no consistent effect on milk production. Plasma fluoride concentrations closely followed current fluoride intake. Urinary fluoride concentrations varied with intake but remained elevated during low intake. Skeletal fluoride retention was directly related to total fluoride intake and not to pattern of intake. The degree of dental fluorosis was related to the amount of fluoride fed and to the plasma fluoride concentration at the time each incisor was developing. The most severe effects of fluoride ingestion were in high and low intake. These animals had severly worn molar teeth, extensive osteofluorosis, and they experienced periods of extreme lameness. Short periods of high fluoride intake balanced by periods of lower intake were more damaging to cattle than constant exposure to the same average yearly intake.

  7. Obstacles to extending fluoridation in the United States.

    Science.gov (United States)

    Neenan, M E

    1996-09-01

    The purpose of this paper is two-fold: (1) to describe the current extent of water fluoridation in the United States; (2) to address the major obstacles to attaining 75 per cent fluoridation by the year 2000. While 62.1 per cent of the US population has access to fluoridated public water systems, more than 32 million people need to be added to the fluoridation census, primarily from the cities. The legal framework for implementing fluoridation is considered at the state level; a review of fluoridation actions at the local level is presented. The impact of forces affecting the extension of fluoridation in the United States is described: (1) demographic trends--urbanisation, race, ethnicity, language, immigration, age, education levels, housing, income and poverty levels; (2) external environmental forces/political climate; (3) media influence on public opinion and public policy; (4) voter apathy/lack of awareness of the benefits of fluoridation; (5) perceptions of risks vs. benefits; (6) lack of political campaign skills; and (7) legal issues.

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

    Science.gov (United States)

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

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

    NARCIS (Netherlands)

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

    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

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

    DEFF Research Database (Denmark)

    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...

  11. Mechanisms of action of fluoride for caries control

    NARCIS (Netherlands)

    Buzalaf, M.A.R.; Pessan, J.P.; Honório, H.M.; ten Cate, J.M.; Buzalaf, M.A.R.

    2011-01-01

    Fluoride was introduced into dentistry over 70 years ago, and it is now recognized as the main factor responsible for the dramatic decline in caries prevalence that has been observed worldwide. However, excessive fluoride intake during the period of tooth development can cause dental fluorosis. In o

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

    DEFF Research Database (Denmark)

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

    1997-01-01

    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, bas...

  13. Poisoning by coal smoke containing arsenic and fluoride

    Energy Technology Data Exchange (ETDEWEB)

    An, D.; He, Y.G.; Hu, Q.X. [Guizhou Sanitary and Epidemiological Station, Guiyang (China)

    1997-02-01

    An investigation was made into a disease involving skin pigmentation, keratosis of the hands and feet, dental discoloration, and generalized bone and joint pain, stiffness and rigidity, in the village of Bazhi, Zhijin County, Ghizhou Province, People`s Republic of China. Measurements were made of the arsenic and fluoride levels of coal, water, air, food, urine and hair in Bazhi and a control village, Xinzhai, in which coal with a low arsenic content was used. Up to 188 people, including children, in Bazhi and 752 in Xinzhai, were examined for the presence of chronic arsenium, skeletal fluorosis, dental fluorosis and electrocardiogram abnormalities. The coal in Bazhi was found to contain high levels of arsenic and fluoride resulting, after burning in homes without an adequate chimney systems, in pollution of air and food with arsenic and fluoride. The coal in Xinzhai did not cause arsenic pollution but did produce a higher level of fluoride pollution. It was concluded that the endemic disease in Bazhi was caused by pollution by coal smoke containing arsenic and fluoride. It is suggested that arsenic may act synergistically with fluoride so that a lower level of fluoride may produce fluoride toxicity with dental and skeletal fluorosis.

  14. Anti Streptococcus mutans non fluoride and fluoride containing sealants after adding nano-silver particles

    Directory of Open Access Journals (Sweden)

    Maryam Ghasempour

    2014-04-01

    Full Text Available   Background and Aims: Since recurrent caries are one of the major causes of failure in resin restorations, the production of antibacterial resin composites was always under investigation. The aim of this study was to evaluate the efficacy of fissure sealants containing nanosilver particles against the Streptococcus mutans.   Materials and Methods: In this experimental study, the antibacterial properties of two sealants (with fluoride (Clinpro 3M and without fluoride (Concise 3M was investigated with 0, 0.01, 0.02, 0.03, 0.04, 0.05% w/w after adding nano-silver using direct contact test. Sealants formed on the walls of 500ml micro tube and after curing, they left in contact with bacterial suspension. In periods of 3, 24, 48h, a 10 µl volume of liquid medium was placed in blood agar culture and after 24 h incubation at 37ºC, the number of S.mutans colony was counted by colony counter. Data were analyzed using ANOVA andT-test.   Results: Results reported sealants with fluoride comparing to non fluoride ones had significant effect on inhibition of S.mutans growth (P<0.001. The direct contact test demonstrated that by increasing the amount of nano particles, the bacterial growth was significantly diminished (P<0.001.   Conclusion: While sealants with fluoride demonstrated antibacterial effect, sealants with incorporation of higher weight percentage of nanosilver particles, had stronger and more significant antibacterial effect in direct contact test.

  15. Fluoride microresonators for mid-IR applications

    CERN Document Server

    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.

  16. Hydrogen fluoride overtone technology: Status review

    Science.gov (United States)

    Duncan, William A.; Patterson, Stanley P.; Graves, Bruce R.; Holloman, Miles E.; Sollee, Jeffrey L.

    The hydrogen fluoride (HF) overtone chemical laser concept is being developed as a shorter wavelength alternative to the well known HF fundamental chemical laser to achieve higher brightness space-based laser platforms. This paper provides a brief review of the overtone experimental data base and then concentrates on the design of versatile gain generator hardware for optimizing the Hypersonic Low-Temperature (HYLTE) nozzle concept for HF overtone laser performance. The paper also describes a recent high power demonstration of overtone lasing on a scalable gain generator device that is directly traceable to a space-based laser weapon, utilizing uncooled resonator optics.

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

    Science.gov (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, ethnicity, religion, educational status, or socioeconomic level. Despite the obvious benefits associated with this proven public health measure, slow progress has been made toward achieving the 1990 national fluoridation objectives as listed in "Promoting Health/Preventing Disease: Objectives for the Nation." This paper documents the lagging pace of community fluoridation by reviewing and analyzing data reported in "Fluoridation Census, 1985," a document published in late 1988 by the Public Health Service's Centers for Disease Control. Failure to attain the 1990 objectives is attributable to a combination of circumstances, including their low priority within many local, State, and Federal health agencies, inadequate funding at all levels of government, lack of a coordinated and focused national fluoridation effort, failure of most States to require fluoridation, lack of Federal legislation mandating fluoridation, general apathy of most health professional organizations toward fluoridation, misconceptions by the public about effectiveness and safety and, finally, unrelenting opposition by a highly vocal minority of the lay public. In addition, fluoridation successes have not been consistent among States, with wide variation in accomplishments documented in the reported data.While fluoridation still is one of the most cost effective public health measures available to local,State, and Federal public health agencies, it remains significantly underused nearly a half century after its

  18. The effective use of fluorides in public health

    DEFF Research Database (Denmark)

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

    2005-01-01

    Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research and developm......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 their families, and the issue of cost. We recommend that a community should use no more than one systemic fluoride (i.e. water or salt or milk fluoridation) combined with the use of fluoride toothpastes, and that the prevalence of dental fluorosis should be monitored in order to detect increases in or higher...

  19. Fluoride use in Controlling Dental Caries and Fluorosis

    Directory of Open Access Journals (Sweden)

    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.

  20. Assessment of groundwater quality with respect to fluoride.

    Science.gov (United States)

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

    2008-09-01

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

  1. Fluoride caused thyroid endocrine disruption in male zebrafish (Danio rerio).

    Science.gov (United States)

    Jianjie, Chen; Wenjuan, Xue; Jinling, Cao; Jie, Song; Ruhui, Jia; Meiyan, Li

    2016-02-01

    Excessive fluoride in natural water ecosystem has the potential to detrimentally affect thyroid endocrine system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of fluoride on growth performance, thyroid histopathology, thyroid hormone levels, and gene expressions in the HPT axis in male zebrafish (Danio rerio) exposed to different determined concentrations of 0.1, 0.9, 2.0 and 4.1 M of fluoride to investigate the effects of fluoride on thyroid endocrine system and the potential toxic mechanisms caused by fluoride. The results indicated that the growth of the male zebrafish used in the experiments was significantly inhibited, the thyroid microtrastructure was changed, and the levels of T3 and T4 were disturbed in fluoride-exposed male fish. In addition, the expressional profiles of genes in HPT axis displayed alteration. The expressions of all studied genes were significantly increased in all fluoride-exposed male fish after exposure for 45 days. The transcriptional levels of corticotrophin-releasing hormone (CRH), thyroid-stimulating hormone (TSH), thyroglobulin (TG), sodium iodide symporter (NIS), iodothyronine I (DIO1), and thyroid hormone receptor alpha (TRα) were also elevated in all fluoride-exposed male fish after 90 days of exposure, while the inconsistent expressions were found in the mRNA of iodothyronineⅡ (DIO2), UDP glucuronosyltransferase 1 family a, b (UGT1ab), transthyretin (TTR), and thyroid hormone receptor beta (TRβ). These results demonstrated that fluoride could notably inhibit the growth of zebrafish, and significantly affect thyroid endocrine system by changing the microtrastructure of thyroid, altering thyroid hormone levels and endocrine-related gene expressions in male zebrafish. All above indicated that fluoride could pose a great threat to thyroid endocrine system, thus detrimentally affected the normal function of thyroid of male zebrafish.

  2. Milk fluoridation for the prevention of dental caries

    Directory of Open Access Journals (Sweden)

    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.

  3. Unsteady growth of ammonium chloride dendrites

    Science.gov (United States)

    Martyushev, L. M.; Terentiev, P. S.; Soboleva, A. S.

    2016-02-01

    Growth of ammonium chloride dendrites from aqueous solution is experimentally investigated. The growth rate υ and the radius ρ of curvature of branches are measured as a function of the relative supersaturation Δ for steady and unsteady growth conditions. It is shown that the experimental results are quantitatively described by the dependences ρ=a/Δ+b, υ=cΔ2, where the factors for primary branches are a=(1.3±0.2)·10-7 m, b=(2.5±0.4)·10-7 m, and c=(2.2±0.3)·10-4 m/s. The factor c is found to be approximately 7 times smaller for the side branches than that for the primary branches.

  4. Efficient cellulose solvent: quaternary ammonium chlorides.

    Science.gov (United States)

    Kostag, Marc; Liebert, Tim; El Seoud, Omar A; Heinze, Thomas

    2013-10-01

    Pure quaternary tetraalkylammonium chlorides with one long alkyl chain dissolved in various organic solvents constitute a new class of cellulose solvents. The electrolytes are prepared in high yields and purity by Menshutkin quaternization, an inexpensive and easy synthesis route. The pure molten tetraalkylammonium chlorides dissolve up to 15 wt% of cellulose. Cosolvents, including N,N-dimethylacetamide (DMA), may be added in large excess, leading to a system of decreased viscosity. Contrary to the well-established solvent DMA/LiCl, cellulose dissolves in DMA/quaternary ammonium chlorides without any pretreatment. Thus, the use of the new solvent avoids some disadvantages of DMA/LiCl and ionic liquids, the most extensively employed solvents for homogeneous cellulose chemistry.

  5. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  6. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Ferric ammonium ferrocyanide. 73.1298 Section 73.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL...) Identity. (1) The color additive ferric ammonium ferrocyanide is the blue pigment obtained by...

  7. How to make a living from anaerobic ammonium oxidation

    NARCIS (Netherlands)

    Kartal, B.; De Almeida, N.M.; Maalcke, W.J.; Op den Camp, H.J.M.; Jetten, M.S.M.; Keltjens, J.T.

    2013-01-01

    Anaerobic ammonium-oxidizing (anammox) bacteria primarily grow by the oxidation of ammonium coupled to nitrite reduction, using CO2 as the sole carbon source. Although they were neglected for a long time, anammox bacteria are encountered in an enormous species (micro)diversity in virtually any anoxi

  8. Ammonium removal from landfill leachate by anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Cabeza, Adelaida [Department of Chemical Engineering, University of Cantabria, Avda. de los Castros s/n. 39005 Santander (Spain); Urtiaga, Ane [Department of Chemical Engineering, University of Cantabria, Avda. de los Castros s/n. 39005 Santander (Spain)]. E-mail: urtiaga@unican.es; Rivero, Maria-Jose [Department of Chemical Engineering, University of Cantabria, Avda. de los Castros s/n. 39005 Santander (Spain); Ortiz, Inmaculada [Department of Chemical Engineering, University of Cantabria, Avda. de los Castros s/n. 39005 Santander (Spain)

    2007-06-18

    The feasibility of removing ammonium from landfill leachates by electrochemical oxidation was studied. Raw leachates and biologically/physico-chemically pretreated leachates from a municipal landfill site were treated. Boron doped diamond was used as anode and stainless steel as cathode, both electrodes with an area of 70 cm{sup 2}. The effects of the applied current density (15-90 mA cm{sup -2}), the initial ammonium concentration (480-2000 mg L{sup -1}), and the initial chloride concentration were experimentally studied. Total ammonium removal was obtained after 360 min of processing and almost half of the initial ammonium nitrogen was oxidized to nitrate. On the other hand, the concentration of chloride enhanced the rate of ammonium oxidation. In addition, the amount of N-NH{sub 4} {sup +} transformed into N-NO{sub 3} {sup -} decreased when additional chloride was provided.

  9. Seasonal patterns of ammonium regeneration from size-fractionated microheterotrophs

    Science.gov (United States)

    Maguer, Jean-François; L'Helguen, Stéphane; Madec, Christian; Le Corre, Pierre

    1999-11-01

    Ammonium regeneration by size-fractionated plankton was measured for 1 year at a coastal station in the shallow well-mixed waters of the western English Channel. Rates of ammonium regeneration in the Journal of Plankton Research, 18, 355-370). Total ammonium regenerated in a year by the microheterotrophs was 15 g N m -2, equivalent to about 60% of the total nitrogen uptake. Microplankton (200-15 μm) accounted for about 50% of the regeneration measured between early spring and late summer. Percent contribution of nanoplankton to total ammonium regeneration varied considerably between the seasons, from very high (83-88%) levels in winter to very low (2-13%) levels in summer. Contribution by picoplankton (nano- and picoplankton fractions, appears to be different from that in deep well-mixed waters. Here, the relative contribution of ciliates and bacteria to ammonium regeneration shows little variation with an increase in macrozooplankton biomass.

  10. Neutralization of a sec-ammonium group unusually stabilized by the "rotaxane effect": synthesis, structure, and dynamic nature of a "free" sec-amine/crown ether-type rotaxane.

    Science.gov (United States)

    Nakazono, Kazuko; Takata, Toshikazu

    2010-12-10

    A fifteen-year riddle has been settled: neutralization, the most popular chemical event, of a crown ether/sec-ammonium salt-type rotaxane has been achieved and a completely nonionic crown ether/sec-amine-type rotaxane isolated. A [2]rotaxane was prepared as a typical substrate from a mixture of dibenzo[24]crown-8 ether (DB24C8) and sec-ammonium hexafluorophosphate (PF(6)) with a terminal hydroxy group through end-capping with 3,5-dimethylbenzoic anhydride in the presence of tributylphosphane as a catalyst in 90% yield. A couple of approaches to the neutralization of the ammonium rotaxane were investigated to isolate the free sec-amine-type rotaxane by decreasing the degree of thermodynamic and kinetic stabilities. One approach was the counteranion-exchange method in which the soft counterion PF(6)(-) was replaced with the fluoride anion by mixing with tetrabutylammonium fluoride, thus decreasing the cationic character of the ammonium moiety. Subsequent simple washing with a base allowed us to isolate the free sec-amine-type rotaxane in a quantitative yield. The other approach was a synthesis based on a protection/deprotection protocol. The acylation of the sec-ammonium moiety with 2,2,2-trichloroethyl chloroformate gave an N-carbamated rotaxane that could be deprotected by treating with zinc in acetic acid to afford the corresponding free sec-amine-type rotaxane in a quantitative yield. The structure of the free sec-amine-type rotaxane was fully confirmed by spectral and analytical data. The generality of the counteranion-exchange method was also confirmed through the neutralization of a bisammonium-type [3]rotaxane. The mechanism was studied from the proposed potential-energy diagram of the rotaxanes with special emphasis on the role of the PF(6)(-) counterion.

  11. 76 FR 19001 - Sulfuryl Fluoride; Addendum to Proposed Order Granting Objections to Tolerances and Denying...

    Science.gov (United States)

    2011-04-06

    ... treatments and for structural fumigation for which there is significant sulfuryl fluoride use and no readily... fluoride/fluoride tolerances for rice commodities associated with direct fumigation of rice that were... phosphine) rather than sulfuryl fluoride. (See Office of Prevention, Pesticides, and Toxic Substances,...

  12. CO2 capture from simulated fuel gas mixtures using semiclathrate hydrates formed by quaternary ammonium salts.

    Science.gov (United States)

    Park, Sungwon; Lee, Seungmin; Lee, Youngjun; Seo, Yongwon

    2013-07-02

    In order to investigate the feasibility of semiclathrate hydrate-based precombustion CO2 capture, thermodynamic, kinetic, and spectroscopic studies were undertaken on the semiclathrate hydrates formed from a fuel gas mixture of H2 (60%) + CO2 (40%) in the presence of quaternary ammonium salts (QASs) such as tetra-n-butylammonium bromide (TBAB) and fluoride (TBAF). The inclusion of QASs demonstrated significantly stabilized hydrate dissociation conditions. This effect was greater for TBAF than TBAB. However, due to the presence of dodecahedral cages that are partially filled with water molecules, TBAF showed a relatively lower gas uptake than TBAB. From the stability condition measurements and compositional analyses, it was found that with only one step of semiclathrate hydrate formation with the fuel gas mixture from the IGCC plants, 95% CO2 can be enriched in the semiclathrate hydrate phase at room temperature. The enclathration of both CO2 and H2 in the cages of the QAS semiclathrate hydrates and the structural transition that results from the inclusion of QASs were confirmed through Raman and (1)H NMR measurements. The experimental results obtained in this study provide the physicochemical background required for understanding selective partitioning and distributions of guest gases in the QAS semiclathrate hydrates and for investigating the feasibility of a semiclathrate hydrate-based precombustion CO2 capture process.

  13. 76 FR 49449 - Continuation of Antidumping Duty Order on Solid Fertilizer Grade Ammonium Nitrate From the...

    Science.gov (United States)

    2011-08-10

    ... Nitrate From the Russian Federation AGENCY: Import Administration, International Trade Administration... duty investigation on solid fertilizer grade ammonium nitrate (``ammonium nitrate'') from the Russian... and the ITC instituted a second sunset review of the ammonium nitrate suspended investigation....

  14. 76 FR 23569 - Termination of the Suspension Agreement on Solid Fertilizer Grade Ammonium Nitrate From the...

    Science.gov (United States)

    2011-04-27

    ... Nitrate From the Russian Federation and Notice of Antidumping Duty Order AGENCY: Import Administration... (``AD'') Investigation on Solid Fertilizer Grade Ammonium Nitrate from the Russian Federation (``the... determine whether imports of solid fertilizer grade ammonium nitrate (``ammonium nitrate'') from Russia...

  15. FLUORIDE SORPTION USING MORRINGA INDICA-BASED ACTIVATED CARBON

    Directory of Open Access Journals (Sweden)

    G. Karthikeyan, S. Siva Ilango

    2007-01-01

    Full Text Available Batch adsorption experiments using activated carbon prepared from Morringa Indica bark were conducted to remove fluoride from aqueous solution. A minimum contact time of 25 min was required for optimum fluoride removal. The influence of adsorbent, dose, pH, co-ions (cations and anions on fluoride removal by the activated carbon has been experimentally verified. The adsorption of fluoride was studied at 30 C, 40 C and 50 C. The kinetics of adsorption and adsorption isotherms at different temperatures were studied. The fluoride adsorption obeyed both Langmuir and Freundlich isotherms and followed a pseudo first order kinetic model. The thermodynamic studies revealed that the fluoride adsorption by Morringa Indica is an endothermic process indicating an increase in sorption rate at higher temperatures. The negative values of G indicate the spontaneity of adsorption. SEM and XRD studies confirmed the surface morphological characteristics of the adsorbent and the deposition of fluoride on the surface of the material.

  16. High Fluoride Dentifrices for Elderly and Vulnerable Adults

    DEFF Research Database (Denmark)

    Ekstrand, Kim Rud

    2016-01-01

    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 se......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 compared...

  17. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium

    Indian Academy of Sciences (India)

    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.

  18. Monitoring of fluoride in water samples using a smartphone

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Saurabh [Akvo Foundation (Netherlands); Krishnan, Sunderrajan [INREM Foundation (India); Rajkumar, Samuel; Halery, Nischal; Balkunde, Pradeep [Akvo Foundation (Netherlands)

    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 0–2 mg l{sup −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. - Highlights: • Fluoride is an inorganic pollutant in ground water, affecting human health. • A colorimetric method for measurement of fluoride in drinking water with smartphone • Measurement is by mixing water with zirconyl xylenol orange complex reagent. • Results are comparable with laboratory-based ion selective fluoride electrode method.

  19. Serum fluoride and sialic acid levels in osteosarcoma.

    Science.gov (United States)

    Sandhu, R; Lal, H; Kundu, Z S; Kharb, S

    2011-12-01

    Osteosarcoma is a rare malignant bone tumor most commonly occurring in children and young adults presenting with painful swelling. Various etiological factors for osteosarcoma are ionizing radiation, family history of bone disorders and cancer, chemicals (fluoride, beryllium, and vinyl chloride), and viruses. Status of fluoride levels in serum of osteosarcoma is still not clear. Recent reports have indicated that there is a link between fluoride exposure and osteosarcoma. Glycoproteins and glycosaminoglycans are an integral part of bone and prolonged exposure to fluoride for long duration has been shown to cause degradation of collagen and ground substance in bones. The present study was planned to analyze serum fluoride, sialic acid, calcium, phosphorus, and alkaline phosphatase levels in 25 patients of osteosarcoma and age- and sex-matched subjects with bone-forming tumours other than osteosarcoma and musculo-skeletal pain (controls, 25 each). Fluoride levels were analyzed by ISE and sialic acid was analyzed by Warren's method. Mean serum fluoride concentration was found to be significantly higher in patients with osteosarcoma as compared to the other two groups. The mean value of flouride in patients with other bone-forming tumors was approximately 50% of the group of osteosarcoma; however, it was significantly higher when compared with patients of group I. Serum sialic acid concentration was found to be significantly raised in patients with osteosarcoma as well as in the group with other bone-forming tumors as compared to the group of controls. There was, however, no significant difference in the group of patients of osteosarcoma when compared with group of patients with other bone-forming tumors. These results showing higher level of fluoride with osteosarcoma compared to others suggesting a role of fluoride in the disease.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

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

    2014-01-01

    The prevalence of dental caries (tooth decay) among preschool children is increasing, driven partially by an earlier age of onset of carious lesions. The American Academy of Pediatrics recommends application of 5% sodium fluoride varnish at intervals increasing with caries risk status, as soon as teeth are present. However, the varnishes are marketed for treatment of tooth sensitivity and are regulated as medical devices rather than approved by the US Food and Drug Administration for preventi...

  2. Fluoride and lead adsorption on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    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

  3. Fluoride gases damages on agricultural and ornamental plants

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, V.; Padalino, O.

    1968-01-01

    Reports are presented concerning fluoride gases from a brick furnace, damaging agricultural and ornamental plants: Prunus armeniaca L. var. Reale d'Imola, Vitis vinifera L. var. Cardinal, Gladiolus spp., Pinus pinea L., Iris germanica L., that are particularly sensitive to these gases. There are descriptions of the morphological alterations and the authors have proven the presence of fluoride in the chemically analyzed samples. There is a list of plants found near the brick furnace that have been classified as (I) highly sensitive; (II) moderately sensitive; (III) very little sensitivity; (IV) immune to fluoride gases. 10 references, 9 figures.

  4. Fluoride Varnish Efficacy in Preventing Early Childhood Caries

    OpenAIRE

    Weintraub, J.A.; Ramos-Gomez, F; Jue, B.; Shain, S.; Hoover, C I; Featherstone, J.D.B.; Gansky, S.A.

    2006-01-01

    To determine the efficacy of fluoride varnish (5% NaF, Duraphat®, Colgate) added to caregiver counseling to prevent early childhood caries, we conducted a two-year randomized, dental-examiner-masked clinical trial. Initially, 376 caries-free children, from low-income Chinese or Hispanic San Francisco families, were enrolled (mean age ± standard deviation, 1.8 ± 0.6 yrs). All families received counseling, and children were randomized to the following groups: no fluoride varnish, fluoride varni...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Subcellular localization of ammonium transporters in Dictyostelium discoideum

    Directory of Open Access Journals (Sweden)

    Davis Carter T

    2008-12-01

    Full Text Available Abstract Background With the exception of vertebrates, most organisms have plasma membrane associated ammonium transporters which primarily serve to import a source of nitrogen for nutritional purposes. Dictyostelium discoideum has three ammonium transporters, Amts A, B and C. Our present work used fluorescent fusion proteins to determine the cellular localization of the Amts and tested the hypothesis that the transporters mediate removal of ammonia generated endogenously from the elevated protein catabolism common to many protists. Results Using RFP and YFP fusion constructs driven by the actin 15 promoter, we found that the three ammonium transporters were localized on the plasma membrane and on the membranes of subcellular organelles. AmtA and AmtB were localized on the membranes of endolysosomes and phagosomes, with AmtB further localized on the membranes of contractile vacuoles. AmtC also was localized on subcellular organelles when it was stabilized by coexpression with either the AmtA or AmtB fusion transporter. The three ammonium transporters exported ammonia linearly with regard to time during the first 18 hours of the developmental program as revealed by reduced export in the null strains. The fluorescently tagged transporters rescued export when expressed in the null strains, and thus they were functional transporters. Conclusion Unlike ammonium transporters in most organisms, which import NH3/NH4+ as a nitrogen source, those of Dictyostelium export ammonia/ammonium as a waste product from extensive catabolism of exogenously derived and endogenous proteins. Localization on proteolytic organelles and on the neutral contractile vacuole suggests that Dictyostelium ammonium transporters may have unique subcellular functions and play a role in the maintenance of intracellular ammonium distribution. A lack of correlation between the null strain phenotypes and ammonia excretion properties of the ammonium transporters suggests that it is not

  7. [Reasons of high concentration ammonium in Yellow River, China].

    Science.gov (United States)

    Zhang, Xue-qing; Xia, Xing-hui; Yang, Zhi-feng

    2007-07-01

    Ammonium nitrogen contamination is one of the major problems of the Yellow River in China. The speciation, concentration and sources of nitrogen compounds as well as the water environment conditions of the Yellow River had been analyzed to study the reasons for the fact that the ammonium nitrogen concentration was above the water quality standard. In addition, laboratory experiments had been carried out to investigate the effects of suspended sediment (SS) on nitrification rate. The results indicated that the presence of SS could accelerate the nitrification process, therefore, the effects of SS on nitrification rate was not the reason for the high level of ammonium nitrogen in the river. The excessive and continuous input of nitrogen contaminants to the river was the fundamental reason for the high concentration of ammonium nitrogen. Organic and ammonium nitrogen with high concentration inhibitted the nitrification processes. When the initial NH4+ -N concentrations were 10.1, 18.4 and 28.2 mg/L, nitrification efficiencies were 17.4%, 13.0% and 2.5%, respectively. When the initial organic nitrogen concentrations were 5.5 and 8.6 mg/L, the maximum concentrations of ammonium nitrogen produced by the oxidation of organic nitrogen would reach 0.47 and 1.69 mg/L and they would last for 2 days and 6 days, respectively. The oxygen-consuming organics and toxic substance existing in the river water could inhibit the activity of nitrifying bacteria, and thus lead to the accumulation of ammonium nitrogen. In addition, the high pH value of river water resulted in the high concentration of nonionic ammonium nitrogen which would reduce the activity of nitrifying bacteria and decrease the nitrification rates. Besides, low river runoff, low SS content and low activity of nitrifying bacteria resulted in the high level of ammonium nitrogen of the river in the low water season.

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

    Science.gov (United States)

    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.

  9. Crystallization of heavy metal fluoride glasses

    Science.gov (United States)

    Bansal, Narottam P.; Bruce, Allan J.; Doremus, R. H.; Moynihan, C. T.

    1984-01-01

    The kinetics of crystallization of a number of fluorozirconate glasses were studied using isothermal and dynamic differential scanning calorimetry and X-ray diffraction. The addition of the fluorides LiF, NaF, AlF3, LaF3 to a base glass composition of ZrF4-BaF2 reduced the tendency to crystallize, probably by modifying the viscosity-temperature relation. ZrF4-BaF2-LaF3-AlF3-NaF glass was the most stable against devitrification and perhaps is the best composition for optical fibers with low scattering loss. Some glasses first crystallize out into metastable beta-BaZr2F10 and beta-BaZrF6 phases, which transform into the most stable alpha-phases when heated to higher temperatures. The size of the crystallites was estimated to be about 600 A from X-ray diffraction.

  10. Polymorphism Control of Poly(vinylidene fluoride)

    Science.gov (United States)

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

    2008-03-01

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

  11. Modelling an Ammonium Transporter with SCLS

    Directory of Open Access Journals (Sweden)

    Angelo Troina

    2009-10-01

    Full Text Available The Stochastic Calculus of Looping Sequences (SCLS is a recently proposed modelling language for the representation and simulation of biological systems behaviour. It has been designed with the aim of combining the simplicity of notation of rewrite systems with the advantage of compositionality. It also allows a rather simple and accurate description of biological membranes and their interactions with the environment.In this work we apply SCLS to model a newly discovered ammonium transporter. This transporter is believed to play a fundamental role for plant mineral acquisition, which takes place in the arbuscular mycorrhiza, the most wide-spread plant-fungus symbiosis on earth. Due to its potential application in agriculture this kind of symbiosis is one of the main focuses of the BioBITs project. In our experiments the passage of NH3 / NH4+ from the fungus to the plant has been dissected in known and hypothetical mechanisms; with the model so far we have been able to simulate the behaviour of the system under different conditions. Our simulations confirmed some of the latest experimental results about the LjAMT2;2 transporter. The initial simulation results of the modelling of the symbiosis process are promising and indicate new directions for biological investigations.

  12. Characterization of nanoscopic calcium fluoride films

    Science.gov (United States)

    Rehmer, A.; Kemnitz, E.

    2016-09-01

    Nano metal fluorides are appropriate materials for different applications e.g. heterogeneous catalysis, ceramic materials for laser applications and antireflective layers on glass, respectively. An easy way to synthesize such nano metal fluorides is the fluorolytic sol-gel synthesis which was developed some few years ago for HS-AlF3 [1] and MgF2.[2] CaF2 exhibits similar optical properties as MgF2, and thus, is a promising candidate for antireflective (AR) coatings. That means, CaF2 exhibits a lower refractive index (n500 = 1.44) as compared to common soda lime glass (n500 = 1.53). Hence, we present an easy synthesis approach toward nanoscaled CaF2 sols to fabricate finally AR-CaF2 films by dip coating. Irrespective of the choice of the calcium precursor, the CaF2 films are porous in comparison to thin dense CaF2 films which are generated by physical vapor deposition. The characterization of CaF2 films was performed by different analytical methods like HR-SEM, XPS, EDX, EP (ellipsometric porosimetry), DLS (dynamic light scattering) and CA (contact angle measurement). Beside the good optical and mechanical properties, we have investigated the surface properties of CaF2 films on glass and silicon wafer e.g. surface morphology with elemental composition, open porosity, zeta potentials at the surfaces as well as the free energy of interaction between water and the CaF2 film.

  13. Antimicrobial Polymeric Materials with Quaternary Ammonium and Phosphonium Salts

    Directory of Open Access Journals (Sweden)

    Yan Xue

    2015-02-01

    Full Text Available Polymeric materials containing quaternary ammonium and/or phosphonium salts have been extensively studied and applied to a variety of antimicrobial-relevant areas. With various architectures, polymeric quaternary ammonium/phosphonium salts were prepared using different approaches, exhibiting different antimicrobial activities and potential applications. This review focuses on the state of the art of antimicrobial polymers with quaternary ammonium/phosphonium salts. In particular, it discusses the structure and synthesis method, mechanisms of antimicrobial action, and the comparison of antimicrobial performance between these two kinds of polymers.

  14. Exraction and separation of CERIUM(IV/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    Directory of Open Access Journals (Sweden)

    Y. Li

    2014-07-01

    Full Text Available In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  15. A highly sensitive colorimetric and ratiometric sensor for fluoride ion

    Institute of Scientific and Technical Information of China (English)

    Zhao Wu Xu; Jin Tang; He Tian

    2008-01-01

    A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied.This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.

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

    NARCIS (Netherlands)

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

    2016-01-01

    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

  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

    Directory of Open Access Journals (Sweden)

    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.

  18. Quantitative measure for the "nakedness" of fluoride ion sources.

    Science.gov (United States)

    Christe, Karl O; Jenkins, H Donald Brooke

    2003-08-01

    A quantitative measure for the donor strength or "nakedness" of fluoride ion donors is presented. It is based on the free energy change associated with the transfer of a fluoride ion from the donor to a given acceptor molecule. Born-Haber cycle calculations were used to calculate both the free energy and the enthalpy change for this process. The enthalpy change is given by the sum of the fluoride ion affinity of the acceptor (as defined in strict thermodynamic convention) and the lattice energy difference (DeltaU(POT)) between the fluoride ion donor and the salt formed with the acceptor. Because, for a given acceptor, the fluoride affinity has a constant value, the relative enthalpy (and also the corresponding free energy) changes are governed exclusively by the lattice energy differences. In this study, BF(3), PF(5), AsF(5), and SbF(5) were used as the acceptors, and the following seven fluoride ion donors were evaluated: CsF, N(CH(3))(4)F (TMAF), N-methylurotropinium fluoride (MUF), hexamethylguanidinium fluoride (HMGF), hexamethylpiperidinium fluoride (HMPF), N,N,N-trimethyl-1-adamantylammonium fluoride (TMAAF), and hexakis(dimethylamino)phosphazenium fluoride (HDMAPF). Smooth relationships between the enthalpy changes and the molar volumes of the donor cations were found which asymptotically approach constant values for infinitely large cations. Whereas CsF is a relatively poor F(-) donor [(U(POT)(CsF) - U(POT)(CsSbF(6))) = 213 kJ mol(-)(1)], when compared to N(CH(3))(4)F [(U(POT)(TMAF) - U(POT)(TMASbF(6))) = 69 kJ mol(-)(1)], a 4 times larger cation (phosphazenium salt) and an infinitely large cation are required to decrease DeltaU(POT) to 17 and 0 kJ mol(-)(1), respectively. These results clearly demonstrate that very little is gained by increasing the cation size past a certain level and that secondary factors, such as chemical and physical properties, become overriding considerations.

  19. Fluoride varnish: a primary prevention tool for dental caries.

    Science.gov (United States)

    Ramaswami, Neerrajah

    2008-01-01

    Fluoride varnish is an effective tool that has been proven to prevent dental caries both in primary and permanent dentition. Its ease of use, acceptability and efficacy make it an important tool in the primary prevention of dental caries in high-caries-risk children. There has been an increase in third-party reimbursement for fluoride varnish applications in high-risk children and adults.

  20. Electric field dependence of crystallinity in poly(vinylidene fluoride)

    Energy Technology Data Exchange (ETDEWEB)

    Kepler, R.G.; Anderson, R.A.; Lagasse, R.R.

    1982-05-03

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  1. Electric Field Dependence of Crystallinity in Poly(Vinylidene Fluoride)

    Science.gov (United States)

    Kepler, R. G.; Anderson, R. A.; Lagasse, R. R.

    1982-05-01

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

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

    Science.gov (United States)

    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.

  3. Heterolysis of Dihydrogen by Silver Alkoxides and Fluorides.

    Science.gov (United States)

    Tate, Brandon K; Nguyen, Jenna T; Bacsa, John; Sadighi, Joseph P

    2015-07-01

    Alkoxide-bridged disilver cations react with dihydrogen to form hydride-bridged cations, releasing free alcohol. Hydrogenolysis of neutral silver fluorides affords hydride-bridged disilver cations as their bifluoride salts. These reactions proceed most efficiently when the supporting ligands are expanded N-heterocyclic carbenes (NHCs) derived from 6- and 7-membered cyclic amidinium salts. Kinetics studies show that silver fluoride hydrogenolysis is first-order in both silver and dihydrogen.

  4. Molten fluoride mixtures as possible fission reactor fuels

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, W.R.

    1978-01-01

    Molten mixtures of fluorides with UF/sub 4/ as a component have been used as combined fuel and primary heat transfer agent in experimental high-temperature reactors and have been proposed for use in breeders or converters of /sup 233/U from thorium. Such use places stringent and diverse demands upon the fluid fuel. A brief review of chemical behavior of molten fluorides is given to show some of their strengths and weaknesses for such service.

  5. EXPERIMENTAL STUDY AND NUMERICAL SIMULATION OF FLUORIDE IN SAND

    Institute of Scientific and Technical Information of China (English)

    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.

  6. 14N NQR and relaxation in ammonium nitrate

    Science.gov (United States)

    Stephenson, David

    2015-04-01

    The complete 14N nuclear quadrupole resonance (NQR) spectrum of ammonium nitrate is presented recorded using two double resonance techniques - double contact cross relaxation and zero field NQR. The spectra gave the quadrupole coupling constant (Qcc) and asymmetry parameter ( η) values for the nitro of 611 kHz, 0.229 and that for the ammonium nitrogen of 242 kHz, 0.835. The three relaxation transition probabilities have been determined for both the nitro and ammonium nitrogen atoms. The bi-exponential relaxation times (T 1) were measured at 295 K. The values for nitro are 16.9 s and 10.5 s and that of the ammonium are 23.0 s and 16.4 s.

  7. Synthesis and Antibacterial Activity of Novel Quaternary Ammonium Pyridoxine Derivatives.

    Science.gov (United States)

    Shtyrlin, Nikita V; Sapozhnikov, Sergey V; Koshkin, Sergey A; Iksanova, Alfiya G; Sabirov, Arthur H; Kayumov, Airat R; Nureeva, Aliya A; Zeldi, Marina I; Shtyrlin, Yurii G

    2015-01-01

    A series of 26 quaternary ammonium pyridoxine derivatives were synthesized and their cytotoxicity and antibacterial activities against clinically relevant bacterial strains were tested in vitro. The antibacterial activity of mono-ammonium salts increased with the rise of the lipophilicity and compound 3,3,5-trimethyl-8,8-dioctyl-1,7,8,9-tetrahydro-[1,3]dioxino[5,4-d]pyrrolo[3,4-b]pyridin-8-ium chloride (2d) reaches a maximum among them. Bis-ammonium salt of pyridoxine 4 with two dimethyloctylamine groups also demonstrated high antibacterial activity despite lower lipophilicity. The results of MTT assay indicated that HEK 293 cells were more sensitive than HSF to quaternary ammonium pyridoxine derivatives. Compounds 2d and 4 did not induce the damage of the DNA and might be of interest in the development of new antimicrobials.

  8. Direct esterification of ammonium salts of carboxylic acids

    Science.gov (United States)

    Halpern, Yuval

    2003-06-24

    A non-catalytic process for producing esters, the process comprising reacting an ammonium salt of a carboxylic acid with an alcohol and removing ammonia from the reaction mixture. Selectivities for the desired ester product can exceed 95 percent.

  9. Ammonium removal by modified zeolite from municipal wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ya-ping; GAO Ting-yao; JIANG Shang-ying; CAO Da-wen

    2004-01-01

    Ammonium removal by modified zeolite, H-form and Na-form zeolite, were examined by batch-type methods. The adsorption of ammonium on modified zeolite was exothermic process. The saturation adsorption capacity of ammonium on H-form and Na-form zeolite were 21.23 and 41.15 mg/g, respectively. After ten times adsorption- desorption-readsorption cycles the standard deviations of H-form and Na-form zeolite were 6.34% and 6.59%. The zeolite adsorption process has proved cost effective and practical in reducing ammonium by H-form and Na-form zeolite in municipal wastewater from concentration 27.68 mg/L to 2.80 mg/L and 5.91 mg/L.

  10. {sup 14}N NQR and relaxation in ammonium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Stephenson, David, E-mail: david.stephenson@sta.uwi.edu [University of the West Indies, Chemistry Department (Trinidad and Tobago)

    2015-04-15

    The complete {sup 14}N nuclear quadrupole resonance (NQR) spectrum of ammonium nitrate is presented recorded using two double resonance techniques – double contact cross relaxation and zero field NQR. The spectra gave the quadrupole coupling constant (Qcc) and asymmetry parameter (η) values for the nitro of 611 kHz, 0.229 and that for the ammonium nitrogen of 242 kHz, 0.835. The three relaxation transition probabilities have been determined for both the nitro and ammonium nitrogen atoms. The bi-exponential relaxation times (T {sub 1}) were measured at 295 K. The values for nitro are 16.9 s and 10.5 s and that of the ammonium are 23.0 s and 16.4 s.

  11. Fixed Ammonium Content and Maximum Capacity of Ammonium Fixation in Major Types of Tillage Soils in Hunan Province, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yang-zhu; HUANG Shun-hong; WAN Da-juan; HUANG Yun-xiang; ZHOU Wei-jun; ZOU Ying-bin

    2007-01-01

    In order to understand the status of fixed ammonium, fixed ammonium content, maximum capacity of ammonium fixation, and their influencing factors in major types of tillage soils of Hunan Province, China, were studied with sampling on fields, and laboratory incubation and determination. The main results are summarized as follows: (1) Content of fixed ammonium in the tested soils varies greatly with soil use pattern and the nature of parent material. For the paddy soils, it ranges from 135.4 ± 57.4 to 412.8±32.4 mg kg-1, with 304.7±96.7 mg kg-1 in average; while it ranges from 59.4 to 435.7 mg kg-1, with 230.1 ± 89.2 mg kg1 in average for the upland soils. The soils developed from limnic material and slate had higher fixed ammonium content than the soils developed from granite. The percentage of fixed ammonium to total N in the upland soils is always higher than that in the paddy soils. It ranges from 6.1 ± 3.6% to 16.6 ±4.6%, with 14.0% ± 5.1% in average for the paddy soils and it amounted to 5.8 ±2.0% to 40.1 ± 17.8%, with 23.5 ± 14.2% in average for upland soils. (2) The maximum capacity of ammonium fixation has the same trend with the fixed ammonium content in the tested soils. For all the tested soils, the percentage of recently fixed ammonium to maximum capacity of ammonium fixation is always bellow 20% and it may be due to the fact that the soils have high fertility and high saturation of ammonium-fixing site. (3) The clay content and clay composition in the tested soils are the two important factors influe ncing their fixed ammonium content and maximum capacity of ammonium fixation. The results showed that hydrous mica is the main 2:1 type clay mineral in <0.02 mm clay of the paddy soils, and its content in 0.02-0.002 mm clay is much higher than that in < 0.002 mm clay of the soils. The statistical analysis showed that both the fixed ammonium content and the maximum capacity of ammonium fixation of the paddy soils were positively correlated with

  12. Response of grapevines to fluoride under field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Murray, F.

    1983-07-01

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

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

    Science.gov (United States)

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

    2016-12-27

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

  14. Fluorides in caries prevention and control: empiricism or science.

    Science.gov (United States)

    Ten Cate, J M

    2004-01-01

    The caries-preventive effects of fluoride are beyond any reasonable doubt! Inclusion of fluoride use in caries prevention protocols has resulted in significant reduction in caries prevalence in the majority of the population. Nevertheless, even in low-caries prevalence populations up to 20% of individuals may suffer to an unacceptable degree from caries. In the history of caries research various phases can be discerned. Starting with the initial - laboratory - studies to reveal the mode of action of fluoride, attention later shifted to intra-oral studies and in situ product testing. Currently much emphasis is given to evidence-based dentistry and guidelines for clinical practice, which trend has also focussed the research on fluoride and caries. While on some topics, such as the efficacy of fluoride toothpastes, evidence is convincing, additional research is indicated to resolve remaining questions. One such question is that of high-prevalence individuals for which a comprehensive research programme focussing both on caries aetiological and behavioural aspects should be further developed. Efforts should continue to be directed at improving our understanding of fluoride, in particular on topics where success so far has failed.

  15. Phosphate reduction in a hydroxyapatite fluoride removal system

    Science.gov (United States)

    Egner, A.

    2012-12-01

    Fluorosis is a widespread disease that occurs as a result of excess fluoride consumption and can cause severe tooth and bone deformations. To combat fluorosis, several previous studies have examined the potential to replace traditional bone char filters with synthetic hydroxyapatite. Calcite particles with a synthetic hydroxyapatite coating have been shown to effectively removed fluoride, yet the low-cost method for forming these particles leaves high amounts of phosphate both in synthesis waste-water and in filter effluent. High phosphate in filter effluent is problematic because consumption of extremely high phosphate can leach calcium from bones, further exacerbating the fluoride effect. This study examines ways of reducing and reusing waste. In particular, a method of fluoride removal is explored in which fluorapatite coatings may be formed directly. In preliminary studies, batches of 4.1g of Florida limestone (<710 μm) were equilibrated with 100 mL of 10ppm fluoride. In a control batch containing lime but no added phosphate, 14% treatment was achieved, but with added phosphate, 100% treatment was achieved in all batches. Batches with lower levels of phosphate took longer to reach 100% treatment, ranging from less than 24 hours in the highest phosphate batches to approximately 42 hours in the lowest batches. The lower levels tested were well within reasonable levels for drinking water and reached 0ppm fluoride in 42 hours or less.

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

    Science.gov (United States)

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

    2015-01-01

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

  17. Removal of fluoride from water using aluminium containing compounds

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. High index fluoride materials for 193nm immersion lithography

    Science.gov (United States)

    Nawata, T.; Inui, Y.; Masada, I.; Nishijima, E.; Satoh, H.; Fukuda, T.

    2006-03-01

    We tried to investigate various kinds of metal fluoride materials which have higher gravity than CaF II and cubic crystal system, and we found out barium lithium fluoride (BaLiF 3) and potassium yttrium fluoride (KY 3F 10) as candidates for the last lens material. We have developed unique Czochralski (CZ) machines and techniques for the growth of large calcium fluoride single crystals. And we applied these technologies to the growth of fluoride high index materials. We have succeeded to grow the large BaLiF 3 single crystal with 120mm in diameter and a KY 3F 10 single crystal, and measured their basic properties such as refractive index, VUV transmittance, birefringence, and so on. As a result of our basic research, we found out that BaLiF 3 single crystal is transparent at VUV region, and the refractive index at 193nm is 1.64, and KY 3F 10 single crystal has the index of 1.59 at the wavelength of 193nm which is slightly higher than fused silica. We expect that these fluoride high index materials are useful for the last lens material of the next generation immersion lithography.

  2. Ammonium Metabolism Enzymes Aid Helicobacter pylori Acid Resistance

    OpenAIRE

    2014-01-01

    The gastric pathogen Helicobacter pylori possesses a highly active urease to support acid tolerance. Urea hydrolysis occurs inside the cytoplasm, resulting in the production of NH3 that is immediately protonated to form NH4+. This ammonium must be metabolized or effluxed because its presence within the cell is counterproductive to the goal of raising pH while maintaining a viable proton motive force (PMF). Two compatible hypotheses for mitigating intracellular ammonium toxicity include (i) th...

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

    Science.gov (United States)

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

    2010-01-01

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

  4. Mutagenicity of quaternary ammonium salts containing carbohydrate moieties

    Energy Technology Data Exchange (ETDEWEB)

    Dmochowska, Barbara [Department of Carbohydrate Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Piosik, Jacek; Woziwodzka, Anna [Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Kladki 24, 80-822 Gdansk (Poland); Sikora, Karol; Wisniewski, Andrzej [Department of Carbohydrate Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Wegrzyn, Grzegorz, E-mail: wegrzyn@biotech.univ.gda.pl [Department of Molecular Biology, University of Gdansk, Kladki 24, 80-822 Gdansk (Poland)

    2011-10-15

    Highlights: {yields} A series of quaternary ammonium salts containing carbohydrate moieties, with configuration D-galacto, D-gluco and D-manno, was synthesized and characterized. {yields} The quaternary ammonium salts containing carbohydrate moieties revealed potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. {yields} The N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. {yields} We suggest that quaternary ammonium salts may be more hazardous than previously supposed. - Abstract: Quaternary ammonium salts are widely used in industrial, agricultural, healthcare and domestic applications. They are believed to be safe compounds, with little or no health hazard to humans. However, in this report, we demonstrate that a series of newly synthesized quaternary ammonium salts containing carbohydrate moieties reveal potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. D-Gluco- and D-galacto-derivatives were found to have a higher mutagenic potential than D-manno-derivatives. Among the former groups of compounds, the N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. These results suggest that the safety of quaternary ammonium salts may be lower than previously supposed, indicating a need for testing such compounds for their mutagenicity.

  5. Cationic cellulose nanofibers from waste pulp residues and their nitrate, fluoride, sulphate and phosphate adsorption properties.

    Science.gov (United States)

    Sehaqui, Houssine; Mautner, Andreas; Perez de Larraya, Uxua; Pfenninger, Numa; Tingaut, Philippe; Zimmermann, Tanja

    2016-01-01

    Cationic cellulose nanofibers (CNF) having 3 different contents of positively charged quaternary ammonium groups have been prepared from waste pulp residues according to a water-based modification method involving first the etherification of the pulp with glycidyltrimethylammonium chloride followed by mechanical disintegration. The cationic nanofibers obtained were observed by scanning electron microscopy and the extent of the reaction was evaluated by conductometric titration, ζ-potential measurements, and thermogravimetric analyses. The cationic CNF had a maximum cationic charge content of 1.2mmolg(-1) and positive ζ-potential at various pH values. Sorption of negatively charged contaminants (fluoride, nitrate, phosphate and sulphate ions) and their selectivity onto cationic CNF have been evaluated. Maximum sorption of ∼0.6mmolg(-1) of these ions by CNF was achieved and selectivity adsorption studies showed that cationic CNF are more selective toward multivalent ions (PO4(3-) and SO4(2-)) than monovalent ions (F(-) and NO3(-)). In addition, we demonstrated that cationic CNF can be manufactured into permeable membranes capable of dynamic nitrate adsorption by utilizing a simple paper-making process.

  6. High Temperature Fluoride Salt Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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).

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

    Science.gov (United States)

    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.

  9. 40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.

    Science.gov (United States)

    2010-07-01

    ... ammonium nitrate subcategory. 418.40 Section 418.40 Protection of Environment ENVIRONMENTAL PROTECTION... Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of ammonium...

  10. 76 FR 39847 - Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation; Final Results of the...

    Science.gov (United States)

    2011-07-07

    ... International Trade Administration Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation; Final... investigation on solid fertilizer grade ammonium nitrate (``ammonium nitrate'') from the Russian Federation...: Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation, 64 FR 45236 (August 19, 1999)....

  11. Fluoride inhibition of Sporosarcina pasteurii urease: structure and thermodynamics.

    Science.gov (United States)

    Benini, Stefano; Cianci, Michele; Mazzei, Luca; Ciurli, Stefano

    2014-12-01

    Urease is a nickel-dependent enzyme and a virulence factor for ureolytic bacterial human pathogens, but it is also necessary to convert urea, the most worldwide used fertilizer, into forms of nitrogen that can be taken up by crop plants. A strategy to control the activity of urease for medical and agricultural applications is to use enzyme inhibitors. Fluoride is a known urease inhibitor, but the structural basis of its mode of inhibition is still undetermined. Here, kinetic studies on the fluoride-induced inhibition of urease from Sporosarcina pasteurii, a widespread and highly ureolytic soil bacterium, were performed using isothermal titration calorimetry and revealed a mixed competitive and uncompetitive mechanism. The pH dependence of the inhibition constants, investigated in the 6.5-8.0 range, reveals a predominant uncompetitive mechanism that increases by increasing the pH, and a lesser competitive inhibition that increases by lowering the pH. Ten crystal structures of the enzyme were independently determined using five crystals of the native form and five crystals of the protein crystallized in the presence of fluoride. The analysis of these structures revealed the presence of two fluoride anions coordinated to the Ni(II) ions in the active site, in terminal and bridging positions. The present study consistently supports an interaction of fluoride with the nickel centers in the urease active site in which one fluoride competitively binds to the Ni(II) ion proposed to coordinate urea in the initial step of the catalytic mechanism, while another fluoride uncompetitively substitutes the Ni(II)-bridging hydroxide, blocking its nucleophilic attack on urea.

  12. Profile of Fluoride Release from a Nanohybrid Composite Resin

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. An Overview of Liquid Fluoride Salt Heat Transport Systems

    Energy Technology Data Exchange (ETDEWEB)

    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

  15. An Overview of Liquid Fluoride Salt Heat Transport Systems

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Ida Anjomshoaa

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

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

    Science.gov (United States)

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

    2012-08-01

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

  19. Removal of fluoride ions from aqueous solution by waste mud

    Energy Technology Data Exchange (ETDEWEB)

    Kemer, Baris; Ozdes, Duygu; Gundogdu, Ali; Bulut, Volkan N.; Duran, Celal [Karadeniz Technical University, Faculty of Arts and Sciences, Department of Chemistry, 61080 Trabzon (Turkey); Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr [Erciyes University, Faculty of Arts and Sciences, Department of Chemistry, 38039 Kayseri (Turkey)

    2009-09-15

    The present study was carried out to assess the ability of original waste mud (o-WM) and different types of activated waste mud which are acid-activated (a-WM) and precipitated waste mud (p-WM), in order to remove excess of fluoride from aqueous solution by using batch technique. The p-WM exhibited greater performance than the others. Adsorption studies were conducted as a function of pH, contact time, initial fluoride concentration, adsorbent concentration, temperature, etc. Studies were also performed to understand the effect of some co-existing ions present in aqueous solutions. Adsorption process was found to be almost independent of pH for all types of waste mud. Among the kinetic models tested for p-WM, pseudo-second-order model fitted the kinetic data well with a perfect correlation coefficient value of 1.00. It was found that the adequate time for the adsorption equilibrium of fluoride was only 1 h. Thermodynamic parameters including the Gibbs free energy ({Delta}G{sup o}), enthalpy ({Delta}H{sup o}), and entropy ({Delta}S{sup o}) revealed that adsorption of fluoride ions on the p-WM was feasible, spontaneous and endothermic in the temperature range of 0-40 deg. C. Experimental data showed a good fit with the Langmuir and Freundlich adsorption isotherm models. Results of this study demonstrated the effectiveness and feasibility of WM for removal of fluoride ions from aqueous solution.

  20. Fractionation of bamboo hemicelluloses by graded saturated ammonium sulphate.

    Science.gov (United States)

    Guan, Ying; Zhang, Bing; Qi, Xian-Ming; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2015-09-20

    The hemicelluloses were isolated with 10% KOH at 25°C from dewaxed and delignified bamboo powder. The alkali-soluble hemicelluloses from Sinocalamus affinis were fractionated by ammonium sulphate precipitation method. The bamboo alkali-soluble hemicelluloses yielded seven hemicellulosic fractions obtained at 0, 5, 15, 25, 40, 55, and 70% saturation with ammonium sulphate. It was found that the more branched hemicelluloses were precipitated at higher ammonium sulphate concentrations (55 and 70%), the more linear hemicelluloses were precipitated at lower ammonium sulphate concentrations (0, 5, 15, 25, and 40%). The molecular weights of hemicellulosic fractions become lower from 35,270 (H0) to 18,680 (H70)gmol(-1) with the increasing concentrations of saturated ammonium sulphate from 0 to 70%. Based on the FT-IR, (1)H, (13)C and 2D HSQC NMR studies, the alkali-soluble hemicelluloses were 4-O-methyl-glucuronoarabinoxylans composed of the (1→4)-linked β-d-xylopyranosyl backbone with branches at O-3 of α-L-arabinofuranosyl or at O-2 of 4-O-methyl-α-d-glucuronic acid.

  1. A maritime pine antimicrobial peptide involved in ammonium nutrition.

    Science.gov (United States)

    Canales, Javier; Avila, Concepción; Cánovas, Francisco M

    2011-09-01

    A large family of small cysteine-rich antimicrobial peptides (AMPs) is involved in the innate defence of plants against pathogens. Recently, it has been shown that AMPs may also play important roles in plant growth and development. In previous work, we have identified a gene of the AMP β-barrelin family that was differentially regulated in the roots of maritime pine (Pinus pinaster Ait.) in response to changes in ammonium nutrition. Here, we present the molecular characterization of two AMP genes, PpAMP1 and PpAMP2, showing different molecular structure and physicochemical properties. PpAMP1 and PpAMP2 displayed different expression patterns in maritime pine seedlings and adult trees. Furthermore, our expression analyses indicate that PpAMP1 is the major form of AMP in the tree, and its relative abundance is regulated by ammonium availability. In contrast, PpAMP2 is expressed at much lower levels and it is not regulated by ammonium. To gain new insights into the function of PpAMP1, we over-expressed the recombinant protein in Escherichia coli and demonstrated that PpAMP1 strongly inhibited yeast growth, indicating that it exhibits antimicrobial activity. We have also found that PpAMP1 alters ammonium uptake, suggesting that it is involved in the regulation of ammonium ion flux into pine roots.

  2. Effects of bisphenol A on ammonium assimilation in soybean roots.

    Science.gov (United States)

    Sun, Hai; Wang, Li Hong; Zhou, Qing; Huang, Xiao Hua

    2013-12-01

    Bisphenol A (BPA), which is ubiquitous in the environment, is an example of an endocrine-disrupting compound (EDC). Ammonium assimilation has an important function in plant growth and development. However, insufficient information on the potential effect of BPA on ammonium assimilation in plants is available. In this study, the effects of BPA on ammonium assimilation in roots of soybean seedlings were investigated. During the stress period, 1.5 mg L(-1) of BPA improved glutamine synthetase (GS)/glutamate synthase (GOGAT) cycle and glutamate dehydrogenase (GDH) pathway in ammonium assimilation. The amino acid and the soluble protein contents increased in the soybeans. At 17.2 and 50.0 mg L(-1) of BPA, the GS/GOGAT cycle was inhibited and the GDH pathway was promoted. The amino acid content increased and the soluble protein content decreased. During the recovery period, the GS/GOGAT cycle and the GDH pathway recovered at 1.5 and 17.2 mg L(-1) of BPA but not at 50.0 mg L(-1) of BPA. The amino acid content continuously increased and the soluble protein content decreased compared with those in the control treatment. In summary, BPA treatment could affect the contents of soluble protein and amino acid in the soybean roots by regulating ammonium assimilation.

  3. Removing ammonium from water using modified corncob-biochar.

    Science.gov (United States)

    Vu, Thi Mai; Trinh, Van Tuyen; Doan, Dinh Phuong; Van, Huu Tap; Nguyen, Tien Vinh; Vigneswaran, Saravanamuthu; Ngo, Huu Hao

    2017-02-01

    Ammonium pollution in groundwater and surface water is of major concern in many parts of the world due to the danger it poses to the environment and people's health. This study focuses on the development of a low cost adsorbent, specifically a modified biochar prepared from corncob. Evaluated here is the efficiency of this new material for removing ammonium from synthetic water (ammonium concentration from 10 to 100mg/L). The characteristics of the modified biochar were determined by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that ammonium adsorption on modified biochar strongly depended on pH. Adsorption kinetics of NH4(+)-N using modified biochar followed the pseudo-second order kinetic model. Both Langmuir and Sips adsorption isotherm models could simulate well the adsorption behavior of ammonium on modificated biochar. The highest adsorption capacity of 22.6mg NH4(+)-N/g modified biochar was obtained when the biochar was modified by soaking it in HNO3 6M and NaOH 0.3M for 8h and 24h, respectively. The high adsorption capacity of the modified biochar suggested that it is a promising adsorbent for NH4(+)-N remediation from water.

  4. Difficultly Extractable Fixed Ammonium in Some Soils of China

    Institute of Scientific and Technical Information of China (English)

    CHENBIYUN; CHENGLILI; 等

    1999-01-01

    Ninety-three soil samples and 19 sedimentary rock samples collected from 21 provinces of China were analyzed for their contents of fixed ammonium and total N by Kjeldahl-HF method.Results showed that amount of difficultly extractable fixed ammonium(the fixed ammonium that is not determinable by Kjeldahl procedures commonly used for soils) in soils ranged from 0 to 202 mg kg-1,It was generally more than 50 mg kg-1 in soils in Changji and Turpan districts,Xinjiang,accounting for 3.2%-36.8% with an average of 13.9% of the total N.For some Orthents derived from purple shale and purple sandstone in Sichuan and Hunan provinces and Chao soils derived from secondary loess in Henan Province and Ningxia Autonomous Region it was generally around 30 mg kg-1,accounting for 4%-7% of the total soil N,and for most of the rest of soils studied,with the exception of some subsoils,no or trace difficultly extractable fixed ammonium could be detected.It was sugested that the difficultly extractable fixed ammonium was originated from parent rock,and for slightly weathered soils derived from parent materials rich in this form of N the Kjeldahl method might give underestimation of total soil N.

  5. Quaternary ammonium salt derivatives of allylphenols with peripheral analgesic effect

    Directory of Open Access Journals (Sweden)

    A. B de Oliveira

    1991-01-01

    Full Text Available Ammonium salt derivatives of natural allylphenols were synthesized with the purpose of obtaining potential peripheral analgesics. These drugs, by virtue of their physicochemical properties, would not be able to cross the blood brain barrier. Their inability to enter into the central nervous system (CNS should prevent several adverse effects observed with classical opiate analgesics (Ferreira et al., 1984. Eugenol (1 O-methyleugenol (5 and safrole (9 were submitted to nitration, reduction and permethylation, leading to the ammonium salts 4, 8 and 12. Another strategy applied to eugenol (1, consisting in its conversion to a glycidic ether (13, opening the epoxide ring with secondary amines and methylation, led to the ammonium salts 16 and 17. All these ammonium salts showed significant peripheral analgesic action, in modified version of the Randall-Sellito test (Ferreira et al. 1978, at non-lethal doses. The ammonium salt 8 showed an activity comparable to that of methylnalorphinium, the prototype of an ideal peripheral analgesic (Ferreira et al., 1984.

  6. Estimation of fluoride levels in various commercially available carbonated soft drinks in Chandigarh city, India

    Directory of Open Access Journals (Sweden)

    Mohit Bansal

    2015-01-01

    Full Text Available Introduction: Fluoride has a preventive action on dental caries. However, Excessive ingestion of fluoride from different sources can lead to the development of dental fluorosis. Aim: To estimate fluoride levels in various commercially available carbonated soft drinks available in Chandigarh city. Materials and Methods: Twelve different brands of commercially available soft drinks were purchased from three different places and divided into three groups. Fluoride levels were estimated using fluoride test strips Quantofix 37211 Fluka; Sigma-Aldrich. Results: Fluoride levels ranged from 0.12 to 0.42 mg/dl F with the maximum level in Thumbs up and least in Diet Pepsi. Conclusion: The levels of fluoride varied in various carbonated soft drinks analyzed. This could contribute significantly to the total fluoride intake from all sources and thus be an important risk factor for the development of dental fluorosis.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    LENUS (Irish Health Repository)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Indian Academy of Sciences (India)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    SnehaPanchal; RamtejJ. Verma

    2014-01-01

    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.

  15. Highly Selective Fluoride Recognition by a Simple Carbazole-based Hydrozone Derivative

    Institute of Scientific and Technical Information of China (English)

    TANG Li-jun; ZHAO Guo-you; HUANG Zhen-long; WANG Nan-nan; GUO Jiao-jiao

    2013-01-01

    A simple carbazole hydrozone derivative(1) was synthesized and used as an optical probe for fluoride recognition in CH3CN.Receptor 1 exhibited colorimetric and fluorescent dual-channel response to fluoride anions.Addition of fluoride to a receptor 1 solution in CH3CN induced a distinct color change from yellow to magenta,the solution also displayed significant fluorescence blue shift.Thus receptor 1 exhibited dual-channel responses to fluoride with a high selectivity and sensitivity.

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

    Science.gov (United States)

    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

  17. The biological activity of quaternary ammonium salts (QASs

    Directory of Open Access Journals (Sweden)

    Ewa Obłąk

    2010-04-01

    Full Text Available Quaternary ammonium salts (QASs, especially those of cationic surfactant character, are applied as antibacterial and antifungal disinfectants. QASs affect lipid-enveloped viruses, including human immunodeficiency virus (HIV and hepatitis B virus (HBV, but not non-enveloped viruses. These compounds are extensively used in domestic (as ingredients of shampoos, hair conditioners, agricultural (as fungicides, pesticides, insecticides, healthcare (as medications, and industrial applications (as biocides, fabric softeners, corrosion inhibitors. The extensive use of quaternary ammonium disinfectants in recent years has led to the development of resistance in microorganisms to these drugs. Thus [i]Staphylococcus[/i] [i]aureus[/i] strains contain the plasmid-carrying genes [i]qacA[/i] and [i]qacB [/i]encoding resistance to quaternary ammonium compounds and acriflavine. The membrane proteins QacA and QacB confer multidrug resistance by exporting the compound by the proton motive force which is generated by the transmembrane electrochemical proton gradient.

  18. [The biological activity of quaternary ammonium salts (QASs)].

    Science.gov (United States)

    Obłak, Ewa; Gamian, Andrzej

    2010-04-19

    Quaternary ammonium salts (QASs), especially those of cationic surfactant character, are applied as antibacterial and antifungal disinfectants. QASs affect lipid-enveloped viruses, including human immunodeficiency virus (HIV) and hepatitis B virus (HBV), but not non-enveloped viruses. These compounds are extensively used in domestic (as ingredients of shampoos, hair conditioners), agricultural (as fungicides, pesticides, insecticides), healthcare (as medications), and industrial applications (as biocides, fabric softeners, corrosion inhibitors). The extensive use of quaternary ammonium disinfectants in recent years has led to the development of resistance in microorganisms to these drugs. Thus Staphylococcus aureus strains contain the plasmid-carrying genes qacA and qacB encoding resistance to quaternary ammonium compounds and acriflavine. The membrane proteins QacA and QacB confer multidrug resistance by exporting the compound by the proton motive force which is generated by the transmembrane electrochemical proton gradient.

  19. Rocket Solid Propellant Alternative Based on Ammonium Dinitramide

    Directory of Open Access Journals (Sweden)

    Grigore CICAN

    2017-03-01

    Full Text Available Due to the continuous run for a green environment the current article proposes a new type of solid propellant based on the fairly new synthesized oxidizer, ammonium dinitramide (ADN. Apart of having a higher specific impulse than the worldwide renowned oxidizer, ammonium perchlorate, ADN has the advantage, of leaving behind only nitrogen, oxygen and water after decomposing at high temperatures and therefore totally avoiding the formation of hydrogen chloride fumes. Based on the oxidizer to fuel ratios of the current formulations of the major rocket solid booster (e.g. Space Shuttle’s SRB, Ariane 5’s SRB which comprises mass variations of ammonium perchlorate oxidizer (70-75%, atomized aluminum powder (10-18% and polybutadiene binder (12-20% a new solid propellant was formulated. As previously stated, the new propellant formula and its variations use ADN as oxidizer and erythritol tetranitrate as fuel, keeping the same polybutadiene as binder.

  20. Study on mechanism of isomerization between ammonium thiocyanate and thiourea

    Science.gov (United States)

    Zhang, Chao-Zhi; Niu, Meng-Xiao

    2016-12-01

    Application of ammonium thiocyanate that can be separated from wastewater in coking plant is limited. It may isomerize to thiourea which has widely applied in industry. However, the isomerization yield is low. Moreover, the isomerization temperature is more than 145 °C. In this paper, the isomerization was investigated. The mechanism of the isomerization was supposed based on quantum chemistry calculations. Ammonia was employed as a catalyst to lower isomerization temperature and improved the yield of thiourea in the isomerization reaction. Results of quantum chemical calculation and experiments support the supposed mechanism. The mechanism can be applied in production of thiourea from isomerization of ammonium thiocyanate. The paper suggests a useful way of resourcizing ammonium thiocyanate in wastewater.

  1. Enrichment culture of marine anaerobic ammonium oxidation (anammox) bacteria

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jie

    2016-01-01

    The present study investigates the enrichment of anaerobic ammonium oxidation (anammox) bacteria in the marine environment using sediment samples obtained from the East China Sea and discusses the nitrogen removal efficiency of marine anammox bioreactor. Enrichment of anammox bacteria with simultaneous removal of nitrite and ammonium ions was observed in the Anaerobic Sequencing Batch Reactor under a total nitrogen loading rate of 0.37kg-N m-3day-1. In this study, The nitrogen removal efficiency was up to 80% and the molar-reaction ratio of ammonium, nitrite and nitrate was 1.0:1.22:0.22 which was a little different from a previously reported ratio of 1.0:1.32:0.26 in a freshwater system.

  2. Performance of sulfate-dependent anaerobic ammonium oxidation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The performance of sulfate-dependent anaerobic ammonium oxidation was studied.The results showed that both SO42-and NH4+ were chemically stable under anaerobic conditions.They did not react with each other in the absence of biological catalyst(sludge).The anaerobic digested sludge cultivated in an anaerobic reactor for three years took on the ability of oxidizing ammonium with sulfate anaero-bically.The average reduction of sulfate and ammonium was 71.67 mg.L-1 and 56.82 mg.L-1 at high concentrations.The reaction between SO42-and NH4+ was difficult,though feasible,due to its low standard Gibbs free energy change.The experiment demonstrated that high substrate concentrations and low oxidation-reduction potential(ORP) may be favourable for the biological reaction.

  3. Performance of sulfate-dependent anaerobic ammo-nium oxidation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; ZHENG Ping; HE YuHui; JIN RenCun

    2009-01-01

    The performance of sulfate-dependent anaerobic ammonium oxidation was studied. The results showed that both SO42- and NH4+ were chemically stable under anaerobic conditions. They did not react with each other in the absence of biological catalyst (sludge). The anaerobic digested sludge cultivated in an anaerobic reactor for three years took on the ability of oxidizing ammonium with sulfate anaero-bically. The average reduction of sulfate and ammonium was 71.67 mg.L-1 and 56.82 mg.L-1 at high concentrations.The reaction between SO42- and NH4+ was difficult, though feasible, due to its low standard Gibbs free energy change. The experiment demonstrated that high substrate concentrations and low oxidation-reduction potential (ORP) may be favourable for the biological reaction.

  4. Influence of milk products on fluoride bioavailability in man.

    Science.gov (United States)

    Ekstrand, J; Ehrnebo, M

    1979-09-01

    The effect of milk products on the gastrointestinal absorption of fluoride from sodium fluoride tablets was studied in five healthy subjects. Two different diets were tested: (1) 250 ml standardized milk (3% fat) and (2) 500 ml of milk, 3 pieces of white bread with cheese and 150 ml of yoghurt. The 100% bioavailability of sodium fluoride tablets during fasting was greatly decreased by coadministration of milk products: with Diet 1 the absolute bioavailability calculated from combined plasma and urine data was in the range 50--79% and with Diet 2 it ranged from 50--71%. It is suggested that the decreased bioavailability produced by dairy products should be taken into account when establishing flouride dosage regimens for prophylaxis of caries.

  5. Antimicrobial and fluoride release capacity of orthodontic bonding materials

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Oral microflora in preschool children attending a fluoride varnish program

    DEFF Research Database (Denmark)

    Anderson, Maria; Grindefjord, Margaret; Dahllöf, Göran

    2016-01-01

    hundred seven 3-year-old children were enrolled from a cohort of 3403 preschool children taking part in a community based oral health project. Two hundred sixty-three of them had attended caries-preventive program with semi-annual applications of a fluoride varnish since the age of 1 year (test group......BACKGROUND: To compare the oral microflora in preschool children attending a fluoride varnish program with a reference group receiving a standard oral health program without fluoride varnish applications. A second aim was to relate the microbial composition to the caries prevalence. METHODS: Five......) while 237 had received standard preventive care (reference group). Oral samples were collected with a sterile swab and analysed with checkerboard DNA-DNA hybridization using 12 pre-determined bacterial probes. Caries and background data were collected from clinical examinations and questionnaires...

  8. Texture evolution and infrared optical properties of praseodymium fluoride films

    Science.gov (United States)

    Su, Wei-Tao; Li, Bin; Liu, Ding-Quan; Zhang, Feng-Shan

    2007-10-01

    Praseodymium fluoride (PrF3) thin films were deposited on Ge(1 1 1) and zinc selenide substrates by molybdenum boat evaporation method. The crystal structures of thin film were characterized using XRD technique and the texture coefficients were calculated. The texture of praseodymium fluoride films changes from (3 0 2) to (1 1 0) texture when the temperature increases from 100 °C to 250 °C. Drastic tensile stress makes all the films covered by a network of fine cracks with width of nanometer-scale. The infrared transmission spectrum was measured to investigate the optical properties for all the films. The optical constants of praseodymium fluoride film were determined by using Lorentz oscillator model in the range from 8000 cm-1 to 500 cm-1.

  9. Promoting social welfare through oral health: New Jersey's fluoridation experience.

    Science.gov (United States)

    Mendoza, Roger Lee

    2009-01-01

    This study examines the contentious public health policy of treating community water with fluoride in the United States. The question for scholarly investigation is why water fluoridation has been unsuccessful in several parts of the United States relative to the rest. It addresses this question by looking into the processes of scientific discovery and information dissemination, benefits and risks of science-based health policy, related issues of provision and production, and spatial dimensions of policy development. The case method based on New Jersey's experience in public water fluoridation, was opted for this study. We find that policy debates, which are confined to single key issues, tend to breed binary choices and bipolar debates and result in policy stalemates. Consumer accessibility and desirability of merit goods thus become sharply conflicting social welfare values. They undermine the intent of science-based policies and often make alternative and second-best policies more practical to adopt.

  10. 76 FR 2383 - Proposed HHS Recommendation for Fluoride Concentration in Drinking Water for Prevention of Dental...

    Science.gov (United States)

    2011-01-13

    ... concentration of fluoride in drinking water is that concentration that provides the best balance of protection... were limited to studies ] conducted after the introduction of other sources of fluoride, especially... apparent (McDonagh MS, et al, 2000b; Griffin SO, et al, 2007). Fluoride works primarily to prevent...

  11. Professionally applied fluoride gel in low-caries 10.5-year-olds.

    NARCIS (Netherlands)

    Truin, G.J.; Hof, M.A. van 't

    2005-01-01

    The question has been raised whether low-caries children regularly using fluoride toothpaste will benefit from the professional application of additional fluoride gel. To investigate the caries-reducing effect of semi-annually-applied neutral 1% sodium fluoride gel, we carried out a double-blind ran

  12. A method for producing controlled fluoride release from an orthodontic bracket.

    Science.gov (United States)

    Li, Song; Hobson, Ross S; Bai, Yuxing; Yan, Zhuoqun; Carrick, Thomas E; McCabe, John F

    2007-12-01

    The aim of this study was to manufacture and test, in vitro, a novel modification to provide fluoride-releasing orthodontic brackets. Thirty-two orthodontic brackets were drilled to produce a recess (approximately 1.3 mm in diameter and 0.7 mm in depth) at the centre of the bracket base. Four materials, with and without the addition of sodium fluoride, a glass ionomer cement (Ketac Cem micro), a resin-modified glass ionomer cement (RMGIC; GC Fuji Ortho LC), a zinc phosphate (Zinc Cement Improved), and a resin (Transbond XT) were used to fill the recess in the bracket base. Fluoride release was measured daily during the first week and then weekly for 10 weeks. An ion chromatograph with suppressed conductivity was used for free fluoride ion determination. Statistical analysis to determine the amount of flouride release was undertaken using analysis of variance and Tukey's test. During the first 2 weeks, the resin group, with the addition of 38 per cent sodium fluoride added, released significantly more free fluoride (P < 0.05), but after 2 weeks the fluoride release markedly decreased. After 5 weeks, the RMGIC group, with 15 per cent added sodium fluoride, had significantly higher (P < 0.05) daily fluoride release than the other groups. The findings demonstrated that an appropriate fluoridated material can be used as a fluoride-releasing reservoir in a modified orthodontic bracket to enable it to release fluoride over the period of fixed appliance treatment.

  13. Environmental characteristics of regional groundwater in relation to fluoride poisoning in North China

    Science.gov (United States)

    Liu, Yong; Zhu, Wan Hua

    1991-07-01

    More and more data indicated that high- or low-fluoride-bearing drinking water led to endemic diseases in which fluoride poisoning was caused by high levels of fluoride (fluoride ion content >1.0 mg/I) in drinking water. Fluoride poisoning in North China is characterized by pathological changes of bones and teeth. Much attention has been devoted to the study of fluoride-bearing groundwater in North China because regionally groundwater has been the main source of water supply, and fluoride poisoning has developed to the extent that it affects human health seriously. Results from the studies in North China summarized in this article indicate that regional high-fluoride-bearing groundwater has a regular distribution corresponding with the development of endemic fluoride poisoning and has something to do with paleogeographic and paleoclimatic conditions, geology, and hydrogeology, especially with types of hydrogeochemistry, pH value of groundwater, degree of mineralization, and so forth. High-fluoride-bearing groundwater in relation to fluorosis occurs mainly in North China, and many effective measures have been taken to reduce the fluoride content in drinking water and to cure the disease after analyzing the distribution and environmental characteristics of high-fluoride-bearing groundwater.

  14. Total and free fluoride in toothpastes from some non-established market economy countries.

    NARCIS (Netherlands)

    Loveren, C. van; Moorer, W.R.; Buijs, M.J.; Palenstein Helderman, W.H. van

    2005-01-01

    In 101 fluoride toothpastes, bought in local shops in Burkina Faso (n = 3), China (n = 5), Myanmar (n = 22), Nepal (n = 19), Philippines (n = 13), Syria (n = 22), Togo (n = 7) and Vietnam (n = 10), the total and free ionisable fluoride concentrations were established. The total fluoride concentratio

  15. Dental fluorosis and urinary fluoride in 10-12 years old adolescents of Bushehr port

    Directory of Open Access Journals (Sweden)

    Giti Javan

    2006-02-01

    Full Text Available Background: Fluoride increases tooth resistance to dental caries, but mild toxicity due to excessive ingestion of fluoride can cause dental fluorosis. Drinking water naturally contains fluoride and is a major source of fluoride. In Bushehr port, drinking water is supplied from limestone springs with normal fluoride levels but dental fluorosis is observed. Methods: A total of 95 native school children (between the ages of 10-12 years old were randomly selected from four Bushehr port regions. Dental fluorosis, height and weight were examined. Probable attributing factors of dental fluorosis were also questioned. A 16 to 18 hours urinary fluoride concentration was measured with a fluoride ion selective electrode. Results: Dental fluorosis in four upper incisors was apparent in 52.6 % of the subjects. The urinary fluoride concentration was 2.18 mg/lit. Fluoride concentration in drinking water of schools ranged from 0.41 to 0.58 mg/lit. Forty percent of subjects were caries free. Conclusion: In spite of the normal range of fluoride concentration in the drinking water of Bushehr, dental fluorosis and urinary fluoride concentration are higher than the recommended ranges. Therefore, it is necessary to further investigate the amount and effects of fluoride ingestion in residents of Bushehr province.

  16. Fluoride removal from diluted solutions by Donnan dialysis using full factorial design

    Energy Technology Data Exchange (ETDEWEB)

    Boubakri, Ali; Helali, Nawel; Tlili, Mohamed; Amor, Mohamed Ben [Center of Researches and Water Technologies, Soliman (Turkey)

    2014-03-15

    Excessive fluoride concentration in potable water can lead to fluorosis of teeth and bones. In the present study, Donnan dialysis (DD) is applied for the removal of fluoride ions from diluted sodium fluoride solutions. A four factor two level (2{sup 4}) full factorial design was used to investigate the influence of different physico-chemical parameters on fluoride removal efficiency (Y{sub F}) and fluoride flux (J{sub F}) through anion exchange membrane. The statistical design determines factors which have the important effects on Donnan dialysis performance and studies all interactions among the considered parameters. The four significant factors were initial fluoride concentration, feed flow rate, temperature and agitation speed. The experimental results and statistical analysis show that the temperature and agitation speed have positive effects on fluoride removal efficiency and the initial fluoride concentration has a negative effect. In the case of fluoride flux, feed flow rate and initial concentration are the main effect and all factors have a positive effect. The interaction between studied parameters was not negligible on two responses. A maximum fluoride removal of 75.52% was obtained under optimum conditions and the highest value of fluoride flux obtained was 2.4 mg/cm{sup 2}·h. Empirical regression models were also obtained and used to predict the flux and the fluoride removal profiles with satisfactory results.

  17. Steady state growth of E. Coli in low ammonium environment

    Science.gov (United States)

    Kim, Minsu; Deris, Barret; Zhang, Zhongge; Hwa, Terry

    2011-03-01

    Ammonium is the preferred nitrogen source for many microorganisms. In medium with low ammonium concentrations, enteric bacteria turn on the nitrogen responsive (ntr) genes to assimilate ammonium. Two proteins in E. coli, Glutamine synthetase (GS) and the Ammonium/methylammonium transporter AmtB play crucial roles in this regard. GS is the major ammonium assimilation enzyme below 1mM of NH4 + . AmtB is an inner membrane protein that transports NH4 + across the cell membrane against a concentration gradient. In order to study ammonium uptake at low NH4 + concentration at neutral pH, we developed a microfluidic flow chamber that maintains a homogenous nutrient environment during the course of exponential cell growth, even at very low concentration of nutrients. Cell growth can be accurately monitored using time-lapse microscopy. We followed steady state growth down to micro-molar range of NH4 + for the wild type and Δ amtB strains. The wild type strain is able to maintain the growth rate from 10mM down to a few uM of NH4 + , while the mutant exhibited reduced growth below ~ 20 ~uM of NH4 + . Simultaneous characterization of the expression levels of GS and AmtB using fluorescence reporters reveals that AmtB is turned on already at 1mM, but contributes to function only below ~ 30 ~uM in the wild-type. Down to ~ 20 ~uM of NH4 + , E.~coli can compensate the loss of AmtB by GS alone.

  18. Fluoride Consumption and Its Impact on Oral Health

    Science.gov (United States)

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

    2011-01-01

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

  19. Fluoride Consumption and Its Impact on Oral Health

    Directory of Open Access Journals (Sweden)

    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.

  20. Precipitation of phenyl and phenoxypenicillin from solutions using ammonium sulfate.

    Science.gov (United States)

    Luengo, J M

    1985-09-01

    An easy, rapid, and available method for separating 6-aminopenicillanic acid (6-APA), benzylpenicillin (penicillin G), and other related molecules from aqueous solutions or complex industrial broths is described. A high concentration of ammonium sulphate induces partially or totally the precipitation of the penicillin present in the solutions, while 6-APA, phenylacetic, and phenoxyacetic acid always remain in the supernatant. The filtration through No. 4 Pyrex glass-fiber filter or Whatman 3MM paper permits the separation of the compounds present in the supernatant from the other ones precipitated. The precipitated product was identified, in all cases, as ammonium penicillin. This method is described here for the first time.

  1. Determination of Ammonium Ion in Lake Water by Voltammetry

    Institute of Scientific and Technical Information of China (English)

    Wu Yun-hua; Fei Jun-jie; Dang Xue-ping; Hu Sheng-shui

    2004-01-01

    An electroanalytical method for the determination of armonium ion using a platinized platinum electrode is described. Under optimized analytical conditions, the linear range of the calibration graphs for ammonium ion is 3. 0×10(-5)-5.0×10-3 mol·L-1.The Method has been applide to the determination of ammonium ion in lake water samples and recoveries of 100%-103%0 are obtained. The results obtained are found to be in good agreement with spectrophotometric results.

  2. Aerosol isotopic ammonium signatures over the remote Atlantic Ocean

    Science.gov (United States)

    Lin, C. T.; Jickells, T. D.; Baker, A. R.; Marca, A.; Johnson, M. T.

    2016-05-01

    We report aerosol ammonium 15N signatures for samples collected from research cruises on the South Atlantic and Caribbean using a new high sensitivity method. We confirm a pattern of isotopic signals from generally light (δ15N -5 to -10‰), for aerosols with very low (ocean, to generally heavier values (δ15N +5 to +10‰), for aerosols collected in temperate and tropical latitudes and with higher ammonium concentrations (>2 nmol m-3). We discuss whether this reflects a mixing of aerosols from two end-members (polluted continental and remote marine emissions), or isotopic fractionation during aerosol transport.

  3. Mutagenic activity of quaternary ammonium salt derivatives of carbohydrates

    Science.gov (United States)

    Sikora, Karol; Woziwodzka, Anna; Piosik, Jacek; Podgórska, Beata

    2016-01-01

    Summary This paper presents a study on a series of quaternary ammonium salt (QAS) derivatives of glucopyranosides with an elongated hydrophobic hydrocarbon chain. The new N-[6-(β-D-glucopyranosyloxy)hexyl]ammonium bromides and their O-acetyl derivatives were analyzed via 1H and 13C NMR spectroscopy. The mutagenic activity of the newly synthesized QAS was investigated using two different techniques: The Vibrio harveyi luminescence assay and the Ames test. The obtained results support previous findings contesting QAS safety and indicate that QAS, specifically pyridinium derivatives, might be mutagenic. PMID:27559394

  4. Cytogenetic investigations on leucocytes of cattle intoxicated with fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, A.; Deknudt, G.; Decat, G.; Leonard, E.D.

    1977-04-01

    The sources of atmospheric fluoride include the burning of soft coal and the manufacturing of aluminium, steel, lead, copper, nickel, phosphate fertilizers, brick and pottery kilns. Cattle which grazed in the vicinity of a plant manufacturing enamel and which displayed signs of chronic fluoride poisoning such as osteosclerosis and mottled enamel or dental fluorosis were investigated for the presence of structural chromatid and chromosome aberrations. Venous blood was incubated for 48 h, and 100 cells were analyzed for each animal. No statistical difference in the incidence of such anomalies was observed between the controls and the intoxicated animals.

  5. Fluoride ion promoted deprotection and transesterification in nucleotide triesters.

    Science.gov (United States)

    Ogilvie, K K; Beaucage, S L

    1979-10-10

    Tetrabutylammonium fluoride will remove phenyl, trichloroethyl and cyanoethyl groups from nucleotides. In addition to the desired nucleotide products other results including chain cleavage, phosphofluoridates and cyanoethylated thymidine units may be obtained depending on the conditions used. Fluoride ion has been used to successfully exchange phenyl and trichloroethyl groups for methyl, ethyl and butyl groups in nucleotide triesters. This represents a rapid high yield route to a variety of phosphate esters. The synthesis of a novel nucleotide analogue in which two chains are bridged through their phosphates is described.

  6. Dutch fluoride concentration in perspective; Nederlandse fluoridenconcentratie in perspectief

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, B. [Tauw, Deventer (Netherlands); Van Dijk, C. [Wageningen UR, Wageningen (Netherlands); Van Doorn, W. [Royal Haskoning, Nijmegen (Netherlands)

    2009-08-15

    Recent jurisprudence shows that in grant permitting the non legal aspects of air quality requirements for fluorides should be expressly taken into account. During the decision-making process careful considerations should be made about emissions, background concentrations and possible effects of fluorides [mk]. [Dutch] Uit recente jurisprudentie is gebleken dat bij vergunningverlening nadrukkelijk rekening moet worden gehouden met de niet-wettelijke luchtkwaliteitseisen voor fluoriden. Bij besluitvorming dient een zorgvuldige afweging en motivering plaats te vinden over emissies, achtergrondconcentraties en mogelijke effecten van fluoriden.

  7. Perspectives in the effective use of fluoride in Asia

    DEFF Research Database (Denmark)

    Petersen, P E; Phantumvanit, P

    2012-01-01

    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...... 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...

  8. Stimulated Raman scattering in soft glass fluoride fibers

    DEFF Research Database (Denmark)

    Petersen, Christian; Dupont, Sune Vestergaard Lund; Agger, Christian;

    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....

  9. Stimulated Raman scattering in soft glass fluoride fibers

    DEFF Research Database (Denmark)

    Petersen, Christian; Dupont, Sune; Agger, Christian;

    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....

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

    OpenAIRE

    Gunka Yonkova; Vanja Zhivkova; Andriana Surleva

    2011-01-01

    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 prod...

  11. Recovery of protactinium from molten fluoride nuclear fuel compositions

    Science.gov (United States)

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

    1973-12-25

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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    DEFF Research Database (Denmark)

    Petersen, Poul Erik; Lennon, Michael A

    2004-01-01

    Despite great improvements in the oral health of populations across the world, problems still persist particularly among poor and disadvantaged groups in both developed and developing countries. According to the World Oral Health Report 2003, dental caries remains a major public health problem......, 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...

  14. Aqueous Media Oxidation of Alcohols with Ammonium Persulfate

    Institute of Scientific and Technical Information of China (English)

    IMANZADEH, Gholam Hassan; ZAMANLOO, Mohammad R.; MANSOORI, Yaghoob; KHODAYARI, Ali

    2007-01-01

    Oxidation of series of various primary and secondary alcohols to corresponding carbonyl compounds with ammonium persulfate in aqueous media was described. No over oxidation of primary alcohols to carboxylic acids and secondary alcohols to esters was observed. Under such conditions benzoin was converted to benzoic acid.

  15. New synthetic method and properties of ammonium dinitramide (ADN)

    Energy Technology Data Exchange (ETDEWEB)

    Hatano, H.; Onda, T.; Shi Ino, K.; Kiname, S.I. [Technical Center, Hosoya Kako, Osawa (Japan); Miyazaki, S.; Suzuki, S. [Research et Development Center, Nissan Motor Co, Saitama (Japan)

    1996-12-31

    Ammonium dinitramide (ADN) is one of the energetic materials, its hazard, however, has never been presented yet. In this paper, new synthetic method of ADN and its properties are contained. It has been found out that ADN has little hazard and is a safe energetic compound. (authors) 4 refs.

  16. 75 FR 14082 - Ammonium Salts of Fatty Acids (C8

    Science.gov (United States)

    2010-03-24

    ... diet of humans, animals, and plants and currently have Food and Drug Administration and EPA approved.../kg/day (6 times the limit dose of 1,000 mg/kg/day) on days 2 to 13 of pregnancy and musculo-skeletal... plants. Ammonium salts of fatty acid are not likely to persist in the environment and are expected to...

  17. Increase of water resistance of ammonium nitrate explosives

    Directory of Open Access Journals (Sweden)

    Zulkhair Mansurov

    2012-03-01

    Full Text Available Developed a method of kapsulating of ammonium nitrate with liquid paraffin increase finding explosives in water for 60 minutes. Placing explosives in the plastic shell, the explosive was, as in standing or running water during the day. When conducting field tests failures were absent.

  18. Characterization of ammonium polyuranate powders from a continuous precipitator

    Energy Technology Data Exchange (ETDEWEB)

    Oolman, T.

    1979-01-01

    Ammonium polyuranate powders produced in a continuous, well-mixed precipitator were characterized by means of electron microscopy. The powders were qualitatively analyzed with the scanning electron microscope and the elementary crystallites were quantivatively analyzed with the transmission electron microscope. The results were fit to a kinetic theory of continuous precipitation. A phase analysis was also preformed by x-ray powder diffraction.

  19. Synthetic receptors for ammonium ions using dynamic combinatorial chemistry

    NARCIS (Netherlands)

    Hamieh, Saleh

    2015-01-01

    The general topic of this dissertation is the development of synthetic receptors for organic ammonium ions in near physiological conditions using disulfide dynamic combinatorial chemistry (DCC). Chapter 1 explains the importance of this development and the associated difficulties when using the conv

  20. Carboxylates and the uptake of ammonium by excised maize roots

    NARCIS (Netherlands)

    Breteler, H.

    1975-01-01

    The effect of carboxylates (organic acid anions) on NH 4 uptake was studied by changing the carboxylate level of roots prior to uptake experi ments. Succinate was the most effective stimulator of ammonium uptake. The oxocarboxylates (α-oxoglutarate, oxaloacetate and

  1. Treating leachate mixture with anaerobic ammonium oxidation technology

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-guo; ZHOU Shao-qi

    2006-01-01

    Large amounts of ammonium and a low content of biodegradable chemical oxygen demand(COD) are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen after biochemical treatment.Treatment effect of anaerobic ammonium oxidation (anammox) process on the mixture of the leachate and its biochemical effluent was investigated. The results show that the average removal efficiencies of ammonium, nitric nitrogen and total nitrogen are 87.51%,74.95% and 79.59%, respectively, corresponding to the average ratio of removed nitric nitrogen to ammonium, i.e. 1.14 during the steady phase of anammox activity. The mean removal efficiency of COD is only 24.01% during the experimental period. The demand of total phosphorous for the anammox process is unobvious. Especially, the alkalinity and pH value of the effluent are close to those of the influent during the steady phase of anammox activity. In addition, it is demonstrated that the status of the anammox bioreactor can be indicated by the alkalinity and pH value during the course of the experiment. The anammox bioreactor has shown potential for nitrogen removal in the leachate mixture. However, COD and total phosphorous in the leachate mixture need further treatment for removal efficiencies of COD and total phosphorous are not good in the anammox bioreactor.

  2. Growth features of ammonium hydrogen -tartrate single crystals

    Indian Academy of Sciences (India)

    G Sajeevkumar; R Raveendran; B S Remadevi; Alexander Varghese Vaidyan

    2004-08-01

    Ammonium hydrogen -tartrate (-AHT) single crystals were grown in silica gel. The growth features of these crystals with variation of parameters like specific gravity of the gel, gel pH, acid concentrations, concentration of the feed solution and gel age were studied in detail.

  3. Global modeling of nitrate and ammonium aerosols using EQSAM3

    Science.gov (United States)

    Xu, L.; Penner, J. E.

    2009-12-01

    Atmospheric aerosols, particles suspending in air, are important as they affect human health, air quality, and visibility as well as climate. Sulfate, nitrate, ammonium, chloride and sodium are among the most important inorganic aerosol species in the atmosphere. These compounds are hygroscopic and absorb water under almost all ambient environmental conditions. The uptake of water alters the aerosol size, and causes water to become the constituent with the largest atmospheric aerosol mass, especially when the aerosols grow into fog, haze or clouds. Furthermore, several global model studies have demonstrated that rapid increases in nitrogen emissions could produce enough nitrate in aerosols to offset the expected decline in sulfate forcing by 2100 for the extreme IPCC A2 scenario (Bauer et al., 2007). Although nitrate and ammonium were identified as significant anthropogenic sources of aerosols by a number of modeling studies, most global aerosol models still exclude ammonium-nitrate when the direct aerosol forcing is studied. In this study, the computationally efficient equilibrium model, EQSAM3, is incorporated into the UMICH-IMPACT-nitrate model using the hybrid dynamical solution method (Feng and Penner, 2007). The partitioning of nitrate and ammonium along with the corresponding water uptake is evaluated by comparing the model to the EQUISOLVE II method used in Feng and Penner (2007). The model is also evaluated by comparison with the AERONET data base and satellite-based aerosol optical depths.

  4. Profiling the origin of ammonium nitrate: proof-of-principle

    NARCIS (Netherlands)

    Carol-Visser, J.; Farmache, M.A.; Heijden, A.E.D.M. van der

    2011-01-01

    In many Improvised Explosive Devices (IEDs) the main charge consists of ammonium nitrate (AN). For forensic reasons, screening for the origin of AN is of importance. By assessing specifi c characteristics, diff erent AN batches can be profi led, in this way providing extra information which could le

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-01-01

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

  7. Fluoride and abrasive content in commonly used dentifrices on the Kenyan market.

    Science.gov (United States)

    Mwaniki, D L; Opinya, G N

    1993-05-01

    About one decade ago, a heated debate on the appropriateness of fluoride dentifrices in Kenya culminated in the introduction of no-fluoride brands. Analysis of dentifrices that were available on the market in 1989/1990 confirmed two distinctly different categories, the fluoride and the low or no-fluoride types. Among the former, the mean ionic fluoride concentration ranged between 0.4 and 1.36 mg/g while the total fluoride concentration ranged between 1.15 and 114.68 mg/g. The low or no-fluoride dentifrices had less than 0.03 mg/g ionic fluoride and less than 2.14 mg/g total fluoride. The mean abrasive (powder) content ranged between 26.5 g% and 78.5 g%. The gel categories had markedly lower powder values than the pastes. The ash values of the powders ranged between 15.8 g% and 85 g% and did not have an obvious relationship with the powder content. Despite the obvious risk of increasing exposure to excessive fluoride among children, presently, the situation has reverted to the pre-debate time. Given the ubiquitous nature of ingestable fluoride in the region, provision of guidelines and guidance on the sale of dentifrices by the government and consumer organisations, and increased accountability of the manufacturers are recommended.

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

    Science.gov (United States)

    Panizzi, Mirvaine; Peres, Marco Aurélio

    2008-09-01

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

  9. The use of topical fluoride to prevent or reverse dental caries.

    Science.gov (United States)

    Jacobsen, Peter; Young, Douglas

    2003-01-01

    Topical fluoride has been the main stay of caries prevention for many decades. There are several mechanisms which make it beneficial including inhibiting demineralization, enhancing remineralization, and inhibiting bacterial growth. Topical fluoride is available in many different forms. The concentrations of various fluoride preparations range from 225 parts per million (ppm) fluoride in over-the-counter oral rinses to 22,600 ppm in the fluoride varnishes. The clinician must decide which type of topical preparation is best suited for their patient. Patients with high caries risk may benefit from prescription strength fluorides (along with the other chemical and dietary therapies described in this issue of Special Care in Dentistry). The application of fluoride varnish is an excellent topical form for those patients who have access to dental care and for whom it is difficult to comply with the use of other topical forms.

  10. Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Tanghong; Chen, Wei; Cheng, Lei; Bayliss, Ryan D.; Lin, Feng; Plews, Michael R.; Nordlund, Dennis; Doeff, Marca M.; Persson, Kristin A.; Cabana, Jordi

    2017-02-07

    Reversible intercalation reactions provide the basis for modern battery electrodes. Despite decades of exploration of electrode materials, the potential for materials in the nonoxide chemical space with regards to intercalation chemistry is vast and rather untested. Transition metal fluorides stand out as an obvious target. To this end, we report herein a new family of iron fluoride-based perovskite cathode materials AxK1–xFeF3 (A = Li, Na). By starting with KFeF3, approximately 75% of K+ ions were subsequently replaced by Li+ and Na+ through electrochemical means. X-ray diffraction and Fe X-ray absorption spectroscopy confirmed the existence of intercalation of alkali metal ions in the perovskite structure, which is associated with the Fe2+/3+ redox couple. A computational study by density functional theory showed agreement with the structural and electrochemical data obtained experimentally, which suggested the possibility of fluoride-based materials as potential intercalation electrodes. This study increases our understanding of the intercalation chemistry of ternary fluorides, which could inform efforts toward the exploration of new electrode materials.

  11. Spectroscopy and dynamics of rare earth doped fluorides

    NARCIS (Netherlands)

    Ebens, Willem Omco

    1995-01-01

    The defect structure of RE doped Fluorides has been studied along with the conductivity properties, using a variety of techniques, both experimental and theoretical. Two systems have been studied in detail, which represent two kinds of defect states for RE doped SrFr. The system SrFr:CeF, has been t

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

    Institute of Scientific and Technical Information of China (English)

    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.

  13. Magnetic frustration in ferric fluorides investigated by Moessbauer spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Greneche, J.-M. [UPRESA CNRS 6087, Faculte des Sciences, Universite du Maine, Laboratoire de Physique de l' Etat Condense (France)

    1999-11-15

    The origin of magnetic frustration in antiferromagnetic ionic systems is discussed in terms first of cationic topology and then of competing superexchange and supersuperexchange interactions. Some selected examples based on ferric fluorides and oxyfluorides are presented to illustrate both the origins of magnetic frustration and the contribution of zero-field and in-field Moessbauer experiments.

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

    DEFF Research Database (Denmark)

    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...... fluorosis in low-caries communities but not in socially deprived high-caries populations. CONCLUSIONS: The results reinforced the outstanding role of fluoride toothpaste as an effective caries preventive measure in children.......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...... of the study. The targeted papers were critically assessed concerning design, methodology and performance according to a pre-determined checklist. RESULTS: The initial search revealed 179 papers of which 15 met the inclusion criteria. There was strong evidence that daily use of fluoride toothpaste has...

  15. The dissolution of kaolin by acidic fluoride wastes

    DEFF Research Database (Denmark)

    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...

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

    Science.gov (United States)

    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.

  17. Slow-release fluoride devices: a literature review

    Directory of Open Access Journals (Sweden)

    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.

  18. Measuring Bone Metabolism with Fluoride PET: Methodological Considerations.

    Science.gov (United States)

    Apostolova, Ivayla; Brenner, Winfried

    2010-07-01

    In recent years the more widespread availability of PET systems and the development of hybrid PET/computed tomography (CT) imaging, allowing improved morphologic characterization of sites with increased tracer uptake, have improved the accuracy of diagnosis and strengthened the role of 18F-fluoride PET for quantitative assessment of bone pathology. This article reviews the role of 18F-fluoride PET in the skeleton, with a focus on (1) the underlying physiologic and pathophysiological processes of different conditions of bone metabolism and (2) methodological aspects of quantitative measurement of 18F-fluoride kinetics. Recent comparative studies have demonstrated that 18F-fluoride PET and, to an even greater extent, PET/CT are more accurate than 99mTc-bisphosphonate single-photon emission CT for the identification of malignant and benign lesions of the skeleton. Quantitative 18F-flouride PET has been shown valuable for direct non-invasive assessment of bone metabolism and monitoring response to therapy.

  19. Removal of Fluoride from Aqueous Solutions Using Chitosan Cryogels

    Directory of Open Access Journals (Sweden)

    Anete Jessica Arcos-Arévalo

    2016-01-01

    Full Text Available In this study, crosslinked chitosan cryogels (QE and chitosan’s cryogels modified with iron (QEFe were synthesized. They were characterized by BET, PZC, FTIR, and XPS spectroscopies. Results show a specific surface area of 36.67 and 29.17 m2g−1 and 7.0 and 6.1 of PZC for the cryogels QE and QEFe, respectively. FTIR results show the characteristic bands of amino and hydroxyl groups, while in the XPS analysis, interactions between iron and oxygen with fluorine were observed. The removal of fluoride at temperatures of 303, 313, and 323 K in cryogels was tested. The Ho model is the best fit for the experimental data, suggesting that there is a chemisorption process involved in the removal of fluoride. The Langmuir-Freundlich model is the best to represent the behavior of the cryogels, and it is used to sorbents with heterogeneous surfaces. A maximum fluoride adsorption capacity of 280 and 295 mg F−/g for QE and QEFe, respectively, at 303 K was obtained, showing that the removal of fluoride is favored by the iron incorporated in the polymer matrix of the cryogels. The thermodynamic parameters were obtained for both cryogels, where the values of ΔH° and ΔG° indicate that both systems are endothermic and nonspontaneous.

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

    NARCIS (Netherlands)

    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

  1. Elevated fluoride products enhance remineralization of advanced enamel lesions.

    Science.gov (United States)

    ten Cate, J M; Buijs, M J; Miller, C Chaussain; Exterkate, R A M

    2008-10-01

    Caries prevention might benefit from the use of toothpastes containing over 1500 ppm F. With few clinical studies available, the aim of this pH-cycling study was to investigate the dose response between 0 and 5000 ppm F of de- and remineralization of advanced (> 150 microm) enamel lesions. Treatments included sodium and amine fluoride, and a fluoride-free control. Mineral uptake and loss were assessed from solution calcium changes and microradiographs. Treatments with 5000 ppm F both significantly enhanced remineralization and inhibited demineralization when compared with treatments with 1500 ppm F. Slight differences in favor of amine fluoride over sodium fluoride were observed. The ratio of de- over remineralization rates decreased from 13.8 to 2.1 in the range 0 to 5000 ppm F. As much as 71 (6)% of the remineralized mineral was calculated to be resistant to dissolution during subsequent demineralization periods. With 5000-ppm-F treatments, more demineralizing episodes per day (10 vs. 2 for placebo) would still be repaired by remineralization.

  2. Hydrogen Fluoride in High-mass Star-forming Regions

    NARCIS (Netherlands)

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

    2012-01-01

    Hydrogen fluoride (HF) has been established to be an excellent tracer of molecular hydrogen in diffuse clouds. In denser environments, however, the HF abundance has been shown to be approximately two orders of magnitude lower. We present Herschel/HIFI observations of HF J = 1-0 toward two high-mass

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

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

    2007-01-01

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

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

    NARCIS (Netherlands)

    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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    in the 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  8. [(18)F]-Sodium fluoride uptake in Takayasu arteritis

    NARCIS (Netherlands)

    Alexanderson-Rosas, E; Monroy-Gonzalez, A G; Juarez-Orozco, Luis Eduardo; Martinez-Aguilar, M M; Estrada, E; Soldevilla, I; Garcia-Pérez, O; Soto-Lopez, M E

    2016-01-01

    BACKGROUND: While (18)F-fluorodeoxyglucose and (18)F-sodium fluoride with positron emission tomography relate with inflammation and calcification, their role in the assessment of patients with Takayasu arteritis has not yet been studied. METHODS: We present 5 patients with suspected active metabolic

  9. Electrospinning induced ferroelectricity in poly(vinylidene fluoride) fibers

    Science.gov (United States)

    Baji, Avinash; Mai, Yiu-Wing; Li, Qian; Liu, Yun

    2011-08-01

    Poly(vinylidene fluoride) (PVDF) fibers with diameters ranging from 70 to 400 nm are produced by electrospinning and the effect of fiber size on the ferroelectric β-crystalline phase is determined. Domain switching and associated ferro-/piezo-electric properties of the electrospun PVDF fibers were also determined. The fibers showed well-defined ferroelectric and piezoelectric properties.

  10. Mortality and cancer morbidity after heavy occupational fluoride exposure

    DEFF Research Database (Denmark)

    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...

  11. Maximizing ammonium nitrogen removal from solution using different zeolites.

    Science.gov (United States)

    Penn, Chad J; Warren, Jason G; Smith, Savannah

    2010-01-01

    Zeolite minerals are ideal for removing ammonium nitrogen (NH4(+)-N) from animal wastes, leachates, and industrial effluents. The objectives of this study were to compare NH4+ removal and kinetics among several commercially available zeolites under various conditions and determine if calorimetry could provide information regarding kinetics of NH4+ removal. Ammonium sorption onto potassium (K) saturated zeolites was compared using synthetic vs. natural swine effluent and with either traditional batch-shaken system or a "tea bag" approach in which zeolites were contained in a mesh sack and suspended in a solution of swine effluent. Ammonium sorption was measured at four retention times using a flow-through system, and the resulting heat response was measured using isothermal calorimetry. Ammonium removal was not significantly different in synthetic vs. natural swine effluent. Ammonium removal was lower in batch-stirred compared to batch-shaken systems, suggesting that diffusion between particles was rate-limiting in the former system. Flow-through cells possessing contact times > 100 s displayed greater NH4+ sorption than batch systems, suggesting that maintaining high NH4+ concentration in solution, removal of exchange products, and sufficient reaction time are critical to maximizing NH4+ removal by zeolites. Within 100 s after NH4+ addition, endothermic heat responses indicated that NH4(+)-K+ exchange had peaked; this was followed by significant heat rate reduction for 50 min. This confirmed findings of an initial fast NH4(+)-K+ exchange followed by a slower one and suggests the 100-s period of rapid reaction is an indicator of the minimum flow through retention time required to optimize NH4+ sorption to zeolites used in this study.

  12. Recycle use of magnesium ammonium phosphate to remove ammonium nitrogen from rare-earth wastewater.

    Science.gov (United States)

    Huang, H M; Xiao, X M; Yan, B

    2009-01-01

    This paper presents a recycle MAP process (magnesium ammonium phosphate) to remove NH4-N from a typical rare-earth wastewater. The optimum conditions for the MAP precipitation and recycle use of the MAP with a newly-designed process were investigated in laboratory. The results showed that the pH value and dosages of P (phosphate) and Mg reagents have a significant influence on NH4-N removal, with a maximum removal efficiency of 99.4% at the conditions of pH=9 and Mg:N:P molar ratio=1.2:1:1.2. In the process of recycle use of the MAP, adding some HCl to dissolve MAP decomposition residues could effectively enhance NH4-N removal. The NH4-N removal efficiency reached 99.6% by adding an HCl amount of H+:OH- molar ratio=0.8 into the reused MAP decomposition residues, whereas the NH4-N removal efficiency without addition of HCl was only 96.4%. Moreover, the residual PO4-P from the end of reaction was recovered and the optimum recovery efficiency was achieved at a Mg:P molar ratio=6 and pH=10. Under these optimum conditions, the residual NH4-N and PO4-P concentrations in the treated wastewater, through 6 times of the recycling, were less than 15 mg/L and 1 mg/L, respectively. On the basis of this, an economic evaluation of the recycling MAP was made, and this recycle process could save 48.6% cost used in the chemicals for treating per cubic meter of the rare-earth wastewater, compared to the conventional MAP process.

  13. Electrochemical oxidation of quaternary ammonium electrolytes : Unexpected side reactions in organic electrochemistry

    NARCIS (Netherlands)

    Nouri Nigjeh, Eslam; de Vries, Marcel; Bruins, Andries P.; Bischoff, Rainer; Permentier, Hjalmar P.

    2012-01-01

    Quaternary ammonium salts are among the most widely used electrolytes in organic electrochemistry, but there is little known about their unwanted side oxidation reactions. We have, therefore, studied the constant potential oxidation products of quaternary ammonium electrolytes using mass spectrometr

  14. Antibacterial activity of reactive quaternary ammonium compounds in solution and in nonleachable coatings

    NARCIS (Netherlands)

    Gozzelino, G.; Romero Tobar, D.E.; Chaitiemwong, N.; Hazeleger, W.C.; Beumer, R.R.

    2011-01-01

    Antibacterial polymers suitable for coating applications without leaching of the biocidal component have been obtained by UV copolymerization of acrylic resins with acrylic monomers containing quaternary ammonium moieties. Suitable reactive biocides, based on quaternary ammonium monomers (QAMs), end

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

    Science.gov (United States)

    ten Cate, J M

    1999-12-01

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

  16. Fluoride inhibition of Klebsiella aerogenes urease: mechanistic implications of a pseudo-uncompetitive, slow-binding inhibitor.

    Science.gov (United States)

    Todd, M J; Hausinger, R P

    2000-05-09

    Klebsiella aerogenes urease uses a dinuclear nickel active site to catalyze the hydrolysis of urea. Here, we describe the steady-state and pre-steady-state kinetics of urease inhibition by fluoride. Urease is slowly inhibited by fluoride in both the presence and absence of substrate. Steady-state rate studies yield parallel double-reciprocal plots; however, we show that fluoride interaction with urease is not compatible with classical uncompetitive inhibition. Rather, we propose that fluoride binds to an enzyme state (E) that is in equilibrium with resting enzyme (E) and produced during catalysis. Fluoride binding rates are directly proportional to inhibitor concentration. Substrate reduces both the rate of fluoride binding to urease and the rate of fluoride dissociation from the complex, consistent with urea binding to E and E.F in addition to E. Fluoride inhibition is pH-dependent due to a protonation event linked to fluoride dissociation. Fluoride binding is pH-independent, suggesting that fluoride anion, not HF, is the actual inhibitor. We assess the kinetic results in terms of the known protein crystal structure and evaluate possible molecular interpretations for the structure of the E state, the site of fluoride binding, and the factors associated with fluoride release. Finally, we note that the apparent uncompetitive inhibition by fluoride as reported for several other metalloenzymes may need to be reinterpreted in terms of fluoride interaction with the corresponding E states.

  17. 21 CFR 520.310 - Caramiphen ethanedisulfonate and ammonium chloride tablets.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Caramiphen ethanedisulfonate and ammonium chloride... § 520.310 Caramiphen ethanedisulfonate and ammonium chloride tablets. (a) Specifications. Each tablet contains 10 milligrams of 5st caramiphen ethanedisulfonate and 80 milligrams of ammonium chloride.1 1...

  18. 40 CFR 415.240 - Applicability; description of the ammonium chloride production subcategory.

    Science.gov (United States)

    2010-07-01

    ... ammonium chloride production subcategory. 415.240 Section 415.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Ammonium Chloride Production Subcategory § 415.240 Applicability; description of the ammonium chloride production subcategory. The provisions of this subpart are applicable to...

  19. 77 FR 21527 - Ammonium Nitrate From Russia: Correction to Notice of Opportunity To Request Administrative Review

    Science.gov (United States)

    2012-04-10

    ... International Trade Administration Ammonium Nitrate From Russia: Correction to Notice of Opportunity To Request... of the antidumping duty orders and inadvertently omitted Ammonium Nitrate from Russia, POR 5/2/2011-3... include the Ammonium Nitrate from Russia administrative review in the referenced notice. Dated: April...

  20. 77 FR 32669 - Ammonium Nitrate from Ukraine Institution of a Five-Year Review

    Science.gov (United States)

    2012-06-01

    ... COMMISSION Ammonium Nitrate from Ukraine Institution of a Five-Year Review AGENCY: United States... determine whether revocation of the antidumping duty order on ammonium nitrate from Ukraine would be likely... ammonium nitrate from Ukraine (66 FR 47451). Following the five-year reviews by Commerce and the...

  1. Effect of fluoride-free and fluoridated carbamide peroxide gels on the hardness and surface roughness of aesthetic restorative materials

    Directory of Open Access Journals (Sweden)

    Homayoon Alaghehmand

    2013-01-01

    Full Text Available Background: Bleaching products may show some side effects on soft and hard tissues and restorative materials in the oral cavity. This study evaluated the effect of carbamide peroxide gel with and without fluoride ions on the microhardness and surface roughness of tooth-colored restorative materials. Materials and Methods: In this in-vitro study, 76 cubic specimens (4 mm 3 × 4 mm 3 × 3 mm 3 were fabricated from 4 aesthetic A3-shade restorative materials. These materials consisted of two composite resins and two glass ionomers. The specimens made from each material were treated with the following surface treatments: 1. Control group: The specimens were not bleached and were stored in normal saline. Group 2. Fluoridated 20% carbamide peroxide gel, treated 3 h a day for 4 weeks. Group 3. Treated 1 h a day with fluoride-less 22% carbamide peroxide for two weeks. From each group, three other specimens were selected to be evaluated in terms of changes in surface roughness, under scanning electron microscopy (SEM. Results: In this study, fluoridated 20% carbamide peroxide gel increased the microhardness of the four aesthetic restorative materials. The fluoride-free carbamide peroxide 22% reduced the microhardness of the four used materials, which this change was significant for Vitremer and Amelogen. SEM analyses showed changes in surface roughness of glass ionomer specimens. Conclusion: The effect of bleaching on the microhardness of restorative materials is material dependent. Before the application of bleaching systems on the glass ionomer materials, the application of a protective barrier should be considered.

  2. Anaerobic ammonium oxidation, denitrification and dissimilatory nitrate reduction to ammonium in the East China Sea sediment

    Directory of Open Access Journals (Sweden)

    G. D. Song

    2013-03-01

    Full Text Available Benthic nitrogen transformation pathways were investigated in the sediment of the East China Sea in June of 2010 using the 15N isotope pairing technique. Slurry incubations indicated that denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA as well as nitrate release by nitrate storing organisms occurred in the East China Sea sediments. These four processes did not exist independently, the nitrate release therefore diluted the 15N labeling fraction of NO3−, a part of the 15NH4+ derived from DNRA also formed 30N2 via anammox. Therefore current methods of rate calculations led to over and underestimations of anammox and denitrification respectively. Following the procedure outlined in Thampdrup and Dalsgaard (2002, denitrification rates were slightly underestimated by on average 6% without regard to the effect of nitrate release, while this underestimation could be counteracted by the presence of DNRA. On the contrary, anammox rates calculated from 15NO3− experiment were significantly overestimated by 42% without considering nitrate release. In our study this overestimation could only be compensated 14% by taking DNRA into consideration. In a parallel experiment amended with 15NH4+ + 14NO3−, anammox rates were not significantly influenced by DNRA due to the high background of 15NH4+ addition. Excluding measurements in which bioirrigation was present, integrated denitrification rates decreased from 10 to 4 mmol N m−2 d−1 with water depth, while integrated anammox rates increased from 1.5 to 4.0 mmol N m−2 d−1. Consequently, the relative contribution of anammox to the total N-loss increased from 13% at the shallowest site near the Changjiang estuary to 50% at the deepest site on the outer shelf. This study represents the first time in which anammox has been demonstrated to play a significant role in benthic nitrogen cycling in the East China Sea sediment, especially on the outer shelf. N

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Sources et marché du sulfate d'ammonium Sources of and Market for Ammonium Sulfate

    Directory of Open Access Journals (Sweden)

    Loussouarn C.

    2006-11-01

    Full Text Available Engrais azoté le plus utilisé dans le monde jusqu'en 1970, le sulfate d'ammonium ne représente plus aujourd'hui que 4 % de la fertilisation azotée. Avec une teneur en azote de 21 % seulement, il a été peu à peu remplacé comme engrais universel par des produits plus concentrés, notamment l'urée et le nitrate d'ammonium. Obtenu pour plus de 40 % comme sous-produit dans la synthèse de monomères comme le caprolactame, l'acrylonitrile ou le méthacrylate de méthyle, et pour près de 10 % dans le traitement des gaz de cokerie, sa production dépend largement des développements du marché des fibres synthétiques, et, dans une moindre mesure, de la sidérurgie et de la métallurgie. Dans les pays développés, où la production est essentiellement fatale, le volume du marché est et sera plus fonction de la disponibilité du sulfate d'ammonium que de la demande ou de facteurs de marché; sa consommation ne résidera plus que dans des applications spécifiques pour lesquelles il sera bien adapté. Par contre, l'intérêt croissant pour compenser le déficit en soufre de certains sols, et les qualités agronomiques propres du sulfate d'ammonium laissent entrevoir la possibilité d'un essor de son utilisation dans certaines régions en voie de développernent. Ammonium sulfate was the most worldwide nitrogenous fertilizer used up to 1970. Today, it makes up only 4% of nitrogenous fertilization. With a nitrogen content of only 21%, it has gradually been replaced as a universal fertilizer by more concentrated products, particularly urea and ammonium nitrate. More than 40% of the ammonium sulfate is obtained as a by-product from the synthesis of monomers such as caprolactam, acrylonitrile or methyl methacrylate, and nearly 10% from coking gas processing. Its production depends extensively on the development of the market for synthetic fibers and, to a lesser extent, on the steel and metallurgical industries. In the industrialized countries

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

    Directory of Open Access Journals (Sweden)

    Judith C Barker

    Full Text Available 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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    NARCIS (Netherlands)

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

    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

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

    Institute of Scientific and Technical Information of China (English)

    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.

  14. The first barium tin(II) bromide fluoride

    Science.gov (United States)

    Dénès, Georges; Merazig, Hocine; Muntasar, Abdualhafeed; Porterfield, Robyn

    2014-04-01

    In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF2 and of BaBr2.2H2O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF2 - BaBr2 system, with the yield being maximum at X ≈ 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters ( δ = 3.68 mm/s, Δ = 0.99 mm/s) are similar to those of SnBrF and of Sn2BrF5, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift" that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals ( p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba2+ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.

  15. Synthesis, antimicrobial activity of lamotrigine and its ammonium derivatives

    Indian Academy of Sciences (India)

    Yong Qian; Peng-Cheng Lv; Lei Shi; Rui-Qin Fang; Zhong-Cheng Song; Hai-Liang Zhu

    2009-07-01

    Antiepileptic drug lamotrigine and its thirteen ammonium salt complexes (4a-4m) were synthesized and characterized by IR, elemental analysis, 1H-NMR, and MS spectral methods. Many of the ammonium salts (4a-4m) were first reported. Furthermore, the crystal structure of compound 3 was determined by single crystal X-ray diffraction analysis. All these complexes were tested in vitro for their antibacterial activity (Bacillus subtilis, Staphylococcus aureus, Enterococus faecalis, Escherichia coli, Pseudomonas aeruginosa and Enterobacter cloacae). The results indicated that most of the complexes showed good antibacterial activity against Gram-positive (B. subtilis, S. aureus and S. faecalis), but showed mild, even inactive against Gram-negative bacterial strains.

  16. Thorium adsorption behaviour on mixed ammonium lanthanum oxalate, LAOX

    Energy Technology Data Exchange (ETDEWEB)

    Valentini Ganzerli, M.T.; Maggi, L.; Crespi Caramella, V

    1999-07-01

    The cation-exchange properties of mixed ammonium lanthanum oxalate, LAOX, were studied by batch equilibration as a function of the concentration of some cations, such as alkaline earths or ammonium and of some anions and acids. The distribution coefficients for thorium are high, while U(VI) is not adsorbed over a large acidity range. Thus, the separation of thorium from uranium may be successfully carried out. The experimental conditions of adsorption, elution and recovery of thorium were investigated as well, by using chromatographic columns filled with LAOX, in order to set best the separation conditions from uranyl ions. Instrumental neutron activation analysis, ICP emission spectrometry and the UV spectrometry were used to evaluate the thorium, uranium and lanthanum concentrations00.

  17. Thermal stability assessment of anti-explosive ammonium nitrate

    Institute of Scientific and Technical Information of China (English)

    Lijin Shen; Xuguang Wang

    2005-01-01

    The explosivity experiment of anti-explosive ammonium nitrate (AEAN) shows that the explosive characteristic of AEAN is eliminated. The adiabatic decompositions of ammonium nitrate and AEAN were investigated with an accelerating rate calorimeter (ARC). The curves of thermal decomposition temperature and pressure versus time, self-heating rate and pressure versus temperature for two systems were obtained. The kinetic parameters such as apparent activation energy and pre-exponential factor were calculated.The safety of AEAN was analyzed. It was indicated that AEAN has a higher thermal stability than AN. At the same time, it can be shown that the elimination of its explosive characteristic is due to the improvement on the thermal stability of AEAN.

  18. Anaerobic ammonium oxidation in a bioreactor treating slaughterhouse wastewater

    Directory of Open Access Journals (Sweden)

    V. Reginatto

    2005-12-01

    Full Text Available Ammonium oxidation was thought to be an exclusively aerobic process; however, as recently described in the literature, it is also possible under anaerobic conditions and this process was named ANAMMOX. This work describes the operation of a system consisting of a denitrifying reactor coupled to a nitrifying reactor used for removal of nitrogen from slaughterhouse wastewater. During operation of the denitrifying reactor an average nitrogen ammonium removal rate of 50 mg/Ld was observed. This biomass was used to seed a second reactor, operated in repeated fed batch mode, fed with synthetic medium specific to the growth of bacteria responsible for the ANAMMOX process. The nitrogen loading rate varied between 33 and 67 mgN/Ld and average nitrogen removal was 95% and 40%, respectively. Results of fluorescence in situ hybridization (FISH confirmed the presence of anammox-like microorganisms in the enriched biomass.

  19. Preparation of nanodispersed titania using stabilized ammonium nitrate melts

    KAUST Repository

    Raciulete, Monica

    2010-10-01

    An expedite one-step approach using simple precursors has been proposed to obtain metallic oxide compounds and exemplified by preparation of highly dispersed TiO2. The technique consists in heating to 400500 °C of molten ammonium nitrate stabilized with an organic nitrogen-containing compound (urea, melamine, ammonium oxalate) and containing dissolved metal salt precursor (TiOCl2). The crystallites of the resulting TiO2 demonstrated variable size and shape as a function of stabilizer used. Their activity in photocatalytic oxidation of formic acid also depends on the nature of the stabilizer. The catalysts as-prepared showed high photocatalytic performance, superior to that of the Degussa P25 reference. Nitrogen containing stabilizers play a double role of increasing the process safety and modifying the properties of the solid products. © 2010 Elsevier Inc. All rights reserved.

  20. The nitrogen Sternheimer antishielding factor in the ammonium ion

    Science.gov (United States)

    Fowler, P. W.; Kelly, H. M.; Brown, R. J. C.

    1993-12-01

    Coupled Hartree-Fock calculations in various basis sets yield values in the range 6.7 to 6.8 for the Sternheimer antishielding factor (1 - γ ∞) of the nitrogen nucleus in the ammonium ion. These are in substantial agreement with the value of 9 that is obtained from a model of measured relaxation times in solid ammonium chloride when allowance is made for effects of the crystalline environment on the chloride ion Sternheimer antishielding factor. Other experimental estimates of the nitrogen Sternheimer factor are discussed. The new value is used to derive cation field gradients from measured quadrupole coupling constants in solid NH 4ReO 4 and NH 4IO 4.

  1. Ammonium sulphate precipitation overestimates titres of anti-peptide antisera.

    Science.gov (United States)

    Roth, B; Barkas, T

    1984-01-01

    Precipitation by 50% final saturation of ammonium sulphate, a method commonly used to estimate titres and affinity constants of antibodies, was found consistently to overestimate the titre of anti-peptide antisera when compared with other antibody precipitants. The effect could not be attributed to non-IgG fractions, and similar overestimations were found when pure IgG was used. We suggest that the lower values represent a more physiologically relevant estimation.

  2. Recovering germanium from coal ash by chlorination with ammonium chloride

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new process of enriching germanium from coal ash was developed. The process involves in mixing the coal ash and ammonium chloride and then roasting the mixture to produce germanium chloride that is then absorbed by dilute hydrochloric acid and hydrolyzed to germanium oxide. The germanium recovery reached to 80.2% at the optimum condition: mass ratio of NH4Cl/coal ash is 0.15, roasting temperature 400℃ and roasting time 90 min.

  3. Ammonium photo-production by heterocytous cyanobacteria: potentials and constraints.

    Science.gov (United States)

    Grizeau, Dominique; Bui, Lan Anh; Dupré, Catherine; Legrand, Jack

    2016-08-01

    Over the last decades, production of microalgae and cyanobacteria has been developed for several applications, including novel foods, cosmetic ingredients and more recently biofuel. The sustainability of these promising developments can be hindered by some constraints, such as water and nutrient footprints. This review surveys data on N2-fixing cyanobacteria for biomass production and ways to induce and improve the excretion of ammonium within cultures under aerobic conditions. The nitrogenase complex is oxygen sensitive. Nevertheless, nitrogen fixation occurs under oxic conditions due to cyanobacteria-specific characteristics. For instance, in some cyanobacteria, the vegetative cell differentiation in heterocyts provides a well-adapted anaerobic microenvironment for nitrogenase protection. Therefore, cell cultures of oxygenic cyanobacteria have been grown in laboratory and pilot photobioreactors (Dasgupta et al., 2010; Fontes et al., 1987; Moreno et al., 2003; Nayak & Das, 2013). Biomass production under diazotrophic conditions has been shown to be controlled by environmental factors such as light intensity, temperature, aeration rate, and inorganic carbon concentration, also, more specifically, by the concentration of dissolved oxygen in the culture medium. Currently, there is little information regarding the production of extracellular ammonium by heterocytous cyanobacteria. This review compares the available data on maximum ammonium concentrations and analyses the specific rate production in cultures grown as free or immobilized filamentous cyanobacteria. Extracellular production of ammonium could be coupled, as suggested by recent research on non-diazotrophic cyanobacteria, to that of other high value metabolites. There is little information available regarding the possibility for using diazotrophic cyanobacteria as cellular factories may be in regard of the constraints due to nitrogen fixation.

  4. Proton- and ammonium- sensing by histaminergic neurons controlling wakefulness.

    Directory of Open Access Journals (Sweden)

    Yvgenij eYanovsky

    2012-04-01

    Full Text Available Orexinergic and histaminergic neurons in the posterior hypothalamus are involved in the control of arousal. Extracellular levels of acid /CO2 are fundamental physicochemical signals controlling wakefulness and breathing. Acidification excites orexinergic neurons like the chemosensory neurons in the brain stem. Hypercapnia induces c-Fos expression, a marker for increased neuronal activity, in the rat histaminergic tuberomamillary nucleus (TMN, but the mechanisms of this excitation are unknown. Acid-sensing ion channels (ASICs are gated by protons and also by ammonium. Recordings in rat brain slices revealed now that acidification within the physiological range (pH from 7.3 to 7.0 as well as ammonium chloride (5mM excite histaminergic neurons. We detected variable combinations of 4 known types of ASICs in single TMN neurons, along with the pharmacological properties of pH-induced current. At pH 7.0 however, activation of ASICs in TMN neurons was negligible. Block of type I metabotropic glutamate receptors abolished proton- but not ammonium- induced excitation. Mouse TMN neurons were identified within a novel HDC-Cre transgenic reporter mouse line. In contrast to the rat these lacked pH 7.0-induced excitation and showed only a minimal response to the mGluR I agonist DHPG (0.5µM. Ammonium-induced excitation was similar in mouse and rat. Thus glutamate, which is released by glial cells and orexinergic axons amplifies CO2/acid-induced arousal through the recruitment of the histaminergic system in rat but not in mouse. These results are relevant for the understanding of neuronal mechanisms controlling H+/CO2-induced arousal in hepatic encephalopathy and obstructive sleep apnoea. The new HDC-Cre mouse model will be a useful tool for studying the physiological and pathophysiological roles of the histaminergic system.

  5. Nanomodified vermiculite NMV - a new material for recycling ammonium nitrogen

    Science.gov (United States)

    Rama, Miradije; Laiho, Taina; Eklund, Olav; Lehto, Kirsi; Shebanov, Alex; Smått, Jan-Henrik

    2016-04-01

    Vermiculites ((Mg,Fe,Al)3(Al,Si)4O10(OH)24H2O) are naturally occurring minerals from hydromica group with a high cation exchange capacity and large surface area. Since vermiculite is a hydrated mineral, its structure can be changed with heat. In this study vermiculite samples were heated in an oven until the interlayer distance of them diminished from 14 Å to 11.7 Å. This method for improving vermiculites intake of ammonium ions by heating, is an invention made at the University of Turku. Nanomodified vermiculite (NMV) is able to absorb up to 4.7 wt% of ammonium. NMV can be used as an efficient filter and immobilizer of ammonium in different environments. NMV has been efficiently tested on waste water from a biogas plant, human urine, combustion experiments, industrial chimneys, excrements from farms etc. Ammonium doped vermiculite (ADV) is further developed for fertilizer use. Performed experiments have testified the usability of ADV as a fertilizer. At first step the NMV was processed with the reject water from a biogas plant, were it absorbed NH4+ into the lattice. At second, the ADV was used as nutrient source for garden plants. Geraniums and begonias were used as test plants of the work. Plant growth rate was evaluated based on plant weight. Results showed that significant increase of the growth of geraniums and of begonias were observed when comparing to those cultivations where plants have got normal fertilization. Moreover, ADV has been tested as a fertilizer in greenhouse experiments with spruces and pines. After five months, the weight of the plants that had grown in a substrate containing ADV was 10 times the weight of plants growing in the reference substrate.

  6. Structural basis for Mep2 ammonium transceptor activation by phosphorylation.

    Science.gov (United States)

    van den Berg, Bert; Chembath, Anupama; Jefferies, Damien; Basle, Arnaud; Khalid, Syma; Rutherford, Julian C

    2016-04-18

    Mep2 proteins are fungal transceptors that play an important role as ammonium sensors in fungal development. Mep2 activity is tightly regulated by phosphorylation, but how this is achieved at the molecular level is not clear. Here we report X-ray crystal structures of the Mep2 orthologues from Saccharomyces cerevisiae and Candida albicans and show that under nitrogen-sufficient conditions the transporters are not phosphorylated and present in closed, inactive conformations. Relative to the open bacterial ammonium transporters, non-phosphorylated Mep2 exhibits shifts in cytoplasmic loops and the C-terminal region (CTR) to occlude the cytoplasmic exit of the channel and to interact with His2 of the twin-His motif. The phosphorylation site in the CTR is solvent accessible and located in a negatively charged pocket ∼30 Å away from the channel exit. The crystal structure of phosphorylation-mimicking Mep2 variants from C. albicans show large conformational changes in a conserved and functionally important region of the CTR. The results allow us to propose a model for regulation of eukaryotic ammonium transport by phosphorylation.

  7. Removal of chloridazon by natural and ammonium kerolite samples

    Science.gov (United States)

    Socías-Viciana, M. M.; Tévar de Fez, J.; Ureña-Amate, M. D.; González-Pradas, E.; Fernández-Pérez, M.; Flores-Céspedes, F.

    2006-06-01

    The adsorption of chloridazon (5-amino-4-chloro-2-phenylpyridazin-3(2H)-one) on natural and ammonium kerolite samples from aqueous solution at 10, 25 and 40 °C has been studied by using batch experiments. The experimental data points were fitted to the Langmuir equation in order to calculate the adsorption capacities ( Xm) of the samples; two straight lines were obtained, which indicates that the adsorption process takes place in two different stages. Values for Xm1 (first stage) ranged from 1.1 × 10 -2 mol kg -1 for natural kerolite at 40 °C up to 5.1 × 10 -2 mol kg -1 for ammonium kerolite at 10 °C and the values for Xm2 (second stage) ranged from 9.1 × 10 -2 mol kg -1 for natural kerolite at 40 °C up to 14 × 10 -2 mol kg -1 for natural kerolite at 10 °C. The adsorption experiments showed on the one hand, that the ammonium kerolite is more effective than natural kerolite to adsorb chloridazon in the range of temperature studied and on the other hand, that the lower temperature, the more effective the adsorption of chloridazon on the adsorbents studied.

  8. Extraction Factor Of Pure Ammonium Paratungstate From Tungsten Scraps

    Directory of Open Access Journals (Sweden)

    Pee J.-H.

    2015-06-01

    Full Text Available Typical oxidation process of tungsten scraps was modified by the rotary kiln with oxygen burner to increase the oxidation rate of tungsten scraps. Also to accelerate the solubility of solid oxidized products, the hydrothermal reflux method was adapted. By heating tungsten scraps in rotary kiln with oxygen burner at around 900° for 2hrs, the scraps was oxidized completely. Then oxidized products (WO3 and CoWO4 was fully dissolved in the solution of NaOH by hydrothermal reflux method at 150° for 2hrs. The dissolution rate of oxidized products was increased with increasing the reaction temperature and concentration of NaOH. And then CaWO4 and H2WO4 could be generated from the aqueous sodium tungstate solution. Ammonium paratungstate (APT also could be produced from tungstic acid using by aqueous ammonium solution. The morphologies (cubic and plate types of APT was controlled by the stirring process of purified solution of ammonium paratungstate.

  9. Ammonium nitrogen in fetuses of urea-treated sheep.

    Science.gov (United States)

    Yelverton, C C; Roller, M H; Swanson, R N

    1975-02-01

    Eight pregnant Southdown ewes were treated (by drench) with 12.5 ml of 3.3 M urea solution per kilogram of body weight, and ammonium nitrogen concentrations of blood and tissues of these ewes and their fetuses were measured and compared with those of control ewes (given water by drench) and their fetuses. Blood ammonium nitrogen (BAN) and tissue ammonium nitrogen (TAN) concentrations for liver, kidney, spleen, and muscle of ewes and fetuses were determined by an ion-exchange procedure. Samples of blood were collected before treatment, at 30, 90 and 150 minutes after treatment, and at death of the dam. The principal ewes had increasing BAN concentrations with time after drench, and their fetuses had significantly greater (P less than 0.01) BAN concentrations than fetuses from control ewes. All fetuses were alive after death of the dams and had lower TAN values than their dams. The differences in ammonia concentrations between ewes and fetuses were larger in the principal group than in the control group. Except for ewe muscle and fetal liver, all tissues of principals had significantly greater (P less than 0.01) TAN concentrations than those of controls. Muscle of principal ewes and hepatic tissues of their fetuses had greater (P less than 0.05) TAN concentrations than those of control ewes and their fetuses.

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

    Science.gov (United States)

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

    2012-01-01

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

  11. Effect of fluoride in drinking water on children′s intelligence in high and low fluoride areas of Delhi

    Directory of Open Access Journals (Sweden)

    Hansa Kundu

    2015-01-01

    Full Text Available Introduction: Fluoride is one of the indispensable elements for the living being. However, the intake of F above the threshold level can affect the central nervous system even before causing dental or skeletal fluorosis. Aim: The aim was to assess the effect of fluoride in drinking water on the intelligence quotient (IQ of 8-12 years old school going children residing in high and low Fluoride (F areas of Delhi. Materials and Methods: A total of 200 school children were selected, 100 from low F area and 100 from high F area. The IQ of the children was assessed using Ravens Standardized Progressive Matrices Test. Information for each child′s sociodemographic data, mother′s diet during pregnancy, duration of residency in the village, source of drinking water, and duration of drinking water from the source was entered on a specially designed proforma from mothers of children. Height and weight were also recorded for each child to assess the nutritional status. Independent t-test and Chi-square test was used to compare mean IQ scores in high and low fluoridated areas. Pearson′s correlation and multivariate linear regression were used to appraise the issue of all the study variables on IQ. Results: Comparison of mean IQ of children in both high (76.20 ± 19.10 and low F (85.80 ± 18.85 areas showed a significant difference (P = 0.013. Multiple regression analysis between child IQ and all other independent variables revealed that mother′s diet during pregnancy (P = 0.001 along with F in drinking water (P = 0.017 were the independent variables with the greatest explanatory power for child IQ variance (r2 = 0.417 without interaction with other variables. Conclusion: Fluoride in the drinking water was significantly related with the IQ of children. Along with fluoride, mother′s diet during pregnancy was also found to be significantly related with IQ of children. Researches in the same field are further advocated with large sample size and over a

  12. Sources of carrier F-19 in F-18 fluoride

    Science.gov (United States)

    Link, J. M.; Shoner, S. C.; Krohn, K. A.

    2012-12-01

    Fluorine-18 is used for many PET radiopharmaceuticals. Theoretically 18F should be carrier free and a good candidate for nanochemistry. However, 18F has 10 to 1000 times more stable fluorine atoms than radioactive atoms. In order to understand the source of carrier fluoride and other ions associated with 18F radiosynthesis, anion concentrations of different components of 18F target systems as well as solvents and chemicals used in radiosynthesis were measured. Results: The enriched water used for production of 18F had low levels of anions. In general, the sources of anions, particularly of fluoride, were the chemical reagents used for synthesis and trace contaminants in tubing, valves and fittings. A major component of contamination was nitrate from irradiation of dissolved nitrogen gas in the target water.

  13. Sources of carrier F-19 in F-18 fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Link, J. M.; Shoner, S. C.; Krohn, K. A. [University of Washington, Department of Radiology, Molecular Imaging Center, 1959 NE Pacific St., Box 356004, Seattle, WA 98195-6004 (United States)

    2012-12-19

    Fluorine-18 is used for many PET radiopharmaceuticals. Theoretically {sup 18}F should be carrier free and a good candidate for nanochemistry. However, {sup 18}F has 10 to 1000 times more stable fluorine atoms than radioactive atoms. In order to understand the source of carrier fluoride and other ions associated with {sup 18}F radiosynthesis, anion concentrations of different components of {sup 18}F target systems as well as solvents and chemicals used in radiosynthesis were measured. Results: The enriched water used for production of {sup 18}F had low levels of anions. In general, the sources of anions, particularly of fluoride, were the chemical reagents used for synthesis and trace contaminants in tubing, valves and fittings. A major component of contamination was nitrate from irradiation of dissolved nitrogen gas in the target water.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Quaternary ammonium salt N-(dodecyloxycarboxymethyl)-N,N,N-trimethyl ammonium chloride induced alterations in Saccharomyces cerevisiae physiology

    Indian Academy of Sciences (India)

    EWA OBŁĄK; AGATA PIECUCH; EWA MACIASZCZYK-DZIUBIŃSKA; DONATA WAWRZYCKA

    2016-12-01

    We investigated the influence of the quaternary ammonium salt (QAS) called IM (N-(dodecyloxycarboxymethyl)-N,N,N-trimethyl ammonium chloride) on yeast cells of the parental strain and the IM-resistant mutant (EO25 IMR)growth. The phenotype of this mutant was pleiotropic. The IMR mutant exhibited resistance to ethanol, osmotic shockand oxidative stress, as well as increased sensitivity to UV. Moreover, it was noted that mutant EO25 appears to havean increased resistance to clotrimazole, ketoconazole, fluconazole, nystatin and cycloheximide. It also toleratedgrowth in the presence of crystal violet, DTT and metals (selenium, tin, arsenic). It was shown that the presence ofIM decreased ergosterol level in mutant plasma membrane and increased its unsaturation. These results indicatechanges in the cell lipid composition. Western blot analysis showed the induction of Pma1 level by IM. RT-PCRrevealed an increased PMA1 expression after IM treatment.

  16. Evidence for surface nucleation: efflorescence of ammonium sulfate and coated ammonium sulfate aerosol particles

    Science.gov (United States)

    Ciobanu, V. Gabriela; Marcolli, Claudia; Krieger, Ulrich K.; Zuend, Andreas; Peter, Thomas

    2010-05-01

    Aerosol particles are ubiquitous in the atmosphere and can undergo different phase transitions, such as deliquescence and efflorescence. Using optical microscopy, we investigated the efflorescence of ammonium sulfate (AS) in supersaturated AS and 1:1 and 8:1 (by weight) poly(ethylene glycol)-400 (PEG-400)/AS particles, which were deposited as droplets with diameters in the 16 - 35 μm range on a hydrophobically coated slide. The PEG-400/AS particles that are exposed to decreasing relative humidity (RH) exhibit a liquid-liquid phase separation below 90 % RH with the PEG-400 phase surrounding the aqueous AS inner phase (Marcolli and Krieger, 2006; Ciobanu et al., 2009). Pure AS particles effloresced in the RH range from 36.3 to 43.7 % RH, in agreement with literature data (31 - 48 % RH). In contrast, 1:1 PEG-400/AS particles with diameters of the AS phase from 7.2 - 19.2 μm effloresced between 26.8 - 33.9 % RH and 8:1 PEG-400/AS particles with diameters of the AS phase from 1.8 - 7.3 μm between 24.3 - 29.3 % RH. Such low efflorescence relative humidity (ERH) values have never been reached before for AS particles of this size range. We show that neither a potential inhibition of water evaporation via anomalously slow diffusion through the PEG coating, nor the presence of low amounts of PEG-400 in the AS phase, nor different timescales between various experimental techniques could possibly explain the low AS ERH values of PEG-400/AS particles in our setup. High-speed photography of the efflorescence process allowed to monitor the proceeding of the AS crystallization fronts within the particles with millisecond time resolution. The nucleation locations were deduced based on the initial crystals growth locations. Statistical analysis of 31 and 19 efflorescence events for pure AS and 1:1 PEG-400/AS particles, respectively, identified the air/droplet/substrate contact line and the air/droplet interface as preferred nucleation locations in the case of pure AS particles

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

    Science.gov (United States)

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

    2003-01-01

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

  18. Growth kinetics of calcium fluoride at high supersaturation in a fluidized bed reactor.

    Science.gov (United States)

    Jiang, K; Zhou, K G; Yang, Y C; Du, H

    2014-01-01

    Crystallization process in a fluidized bed reactor (FBR) has been regarded as an environmentally friendly technology for the removal and recovery of fluoride from industrial wastewater. The growth kinetics of calcium fluoride at high supersaturation was studied for design, control, and operation of an FBR. The main variables, including supersaturation, superficial velocity, pH value, and particle size of seed that influenced the crystal growth were investigated. Then, a growth model was used to predict the linear growth rate of calcium fluoride at a high influent concentration of fluoride. The pressure difference in the FBR was used as a feature to characterize the growth rate of calcium fluoride. The aggregation and adsorption between seeds and fine particles were proven to be a possible mechanism for growth of calcium fluoride.

  19. Laparoscopic Repair of Morgagni Hernia Using Polyvinylidene Fluoride (PVDF) Mesh.

    Science.gov (United States)

    Godazandeh, Gholamali; Mortazian, Meysam

    2012-10-01

    We report the cases of two patients diagnosed with Morgagni hernia who presented with nonspecific abdominal symptoms. Both underwent laparoscopic surgery that used a dual-sided mesh, polyvinylidene fluoride (PVDF; Dynamesh IPOM®). The procedures were successful and both patients were discharged with no complications. There was no recurrence in 18 months of follow up.Herein is the report of these cases and a literature review.

  20. Effects of Gravity on Processing Heavy Metal Fluoride Fibers

    Science.gov (United States)

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

    1997-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    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.

  2. Fluoride toothpaste utilization behaviour among preschool children in Perlis, Malaysia

    OpenAIRE

    Tay, H.L.; Zainudin, I.S.; Jaafar, N.

    2009-01-01

    Background Very mild fluorosis is quite prevalent in children and one of the sources may be attributed to poor fluoride toothpaste utilization habits. Aim To investigate the frequency of toothbrushing, parental supervision, the person who usually applied the toothpaste, toothpaste swallowing and spitting habits, size of toothbrush, type of toothpaste used and amount of toothpaste used by shape and weight. Methodology Observational cross-sectional study of a representative random sample of 373...

  3. Modified zirconium-eriochrome cyanine R determination of fluoride

    Science.gov (United States)

    Thatcher, L.L.

    1957-01-01

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

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

    OpenAIRE

    Pereira, J. Nunes

    2013-01-01

    Tese de doutoramento em Física (especialidade em Ciências) 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 fl...

  5. Arsenic and fluoride in the groundwater of Mexico.

    Science.gov (United States)

    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.

  6. Laser-matrix-fluoride effects on enamel demineralization.

    Science.gov (United States)

    Hsu, C Y; Jordan, T H; Dederich, D N; Wefel, J S

    2001-09-01

    Laser and fluoride have been shown to inhibit enamel demineralization. However, the role of organic matrix and their interactions remains unclear. This study investigated the interaction among CO2 laser irradiation, fluoride, and the organic matrix on the demineralization of human enamel. Twenty-four molars were selected and cut into halves. One half of each tooth was depleted of its lipid and protein. The other half served as a matched control. Each tooth half had two window areas, treated with a 2.0% NaF gel. All left windows then received a laser treatment. Next, the tooth halves were subjected to a four-day pH-cycling procedure that created caries-like lesions. Tooth sections were cut from the windows, and microradiographs were used for quantification of the demineralization. The combined fluoride-laser treatment led to 98.3% and 95.1% reductions in mineral loss for enamel with and without organic matrix, respectively, when compared with sound enamel.

  7. High performance fluoride optical coatings for DUV optics

    Science.gov (United States)

    Zhang, Lichao; Cai, Xikun

    2014-08-01

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

  8. The effects of airborne fluorides on oral conditions in Morocco

    Energy Technology Data Exchange (ETDEWEB)

    Haikel, Y.; Cahen, P.M.; Turlot, J.C.; Frank, R.M. (Universite Louis Pasteur, Strasbourg (France))

    1989-08-01

    The purpose of this study was to determine the prevalence and severity of dental caries and dental fluorosis, as well as various other oral conditions, in 2378 subjects (ages seven to 60) living in the fluoridated area of Khouribga and the non-fluoridated area of Beni Mellal, Morocco. The community index of dental fluorosis (CFI) ranged from 1.99 to 2.80 in the high-fluoride area: Over 90% of the population was affected, and more than one-third of the subjects showed moderate dental fluorosis. However, in Beni Mellal, more than 96% of the dentate subjects examined were free of dental fluorosis, and the CFI of 0.02 was considered not significant. Significant differences were observed between the two areas with respect to caries prevalence. DMFT and DMFS indices were markedly lower in the fluorosis area of Khouribga. The oral conditions of subjects appeared to be better in Khouribga, where the gingival and calculus indices were significantly lower than in Beni Mellal. The analyses of covariance showed no significant differences in plaque accumulation (PI) between the Khouribga and Beni Mellal samples. However, a close statistical correlation was found between PI and GI in Beni Mellal and Khouribga.

  9. Mechanical Properties of Calcium Fluoride-Based Composite Materials

    Science.gov (United States)

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

    2016-01-01

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

  10. Mechanical Properties of Calcium Fluoride-Based Composite Materials

    Directory of Open Access Journals (Sweden)

    Monika Łukomska-Szymańska

    2016-01-01

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

  11. Calix[4]arene-Based New Neutral Sensors for Fluoride

    Institute of Scientific and Technical Information of China (English)

    LIU,Shun-Ying; MENG,Ling-Zhi; LIU,Xin; HE,Yong-Bing

    2004-01-01

    @@ The development of new receptors which can recognize neutral and charged species has attracted considerable interest in the recent past.[1] Anions such as fluoride, chloride, phosphate and carboxylate play crucial roles in a range of biological phenomena and are implicated in many disease states.[2] Investigations on molecular and/or ionic recognition by calixarenes and their derivatives as synthetic receptors have attracted increasing attention in supramolecular chemistry because of their modifiable structure.[3] However, calix[4]arenes-based neutral receptors containing thiourea and amide groups are still rare. In this paper, we report fluoride selective optical chemosensors 4 and 5, based on calix[4]arene thiourea and amide derivatives, which only show a remarkable absorption change in the presence of fluoride ions, while have no any change upon addition of other anions (Cl- Br-, I-, AcO- and H2PO4-). The association constants are 947 and 2883 mol·L-1, respectively. The synthesis of calix[4]arene derivatives 4 and 5 is outlined in the following Scheme 1.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fathi, M.H. [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 8415683111 (Iran, Islamic Republic of); Zahrani, E. Mohammadi [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 8415683111 (Iran, Islamic Republic of)], E-mail: emohamadizahrani@gmail.com

    2009-05-05

    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 Ca{sub 10}(PO{sub 4}){sub 6}OH{sub 2-x}F{sub x} (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.

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

    Directory of Open Access Journals (Sweden)

    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

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

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    Afsaneh Pakdaman

    2016-04-01

    Full Text Available 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.

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

    Science.gov (United States)

    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

  16. Water defluoridation by hydrotalcite and takovite and subsequent formation of new fluoride-bearing phases.

    Science.gov (United States)

    Guo, Qinghai; Guo, Qingshan

    2013-01-01

    Hydrotalcite, takovite and their calcination products were used to remove fluoride from water at various molar ratios of initial fluoride to solid (F(initial):hydrotalcite or F(initial):takovite) ranging from 0.1 to 2.0, and their theoretical fluoride uptake limit. X-Ray powder diffraction and 19F magic-angle spinning nuclear magnetic resonance spectra were used to characterize the solid samples and to investigate the fluoride removal mechanisms. Water defluoridation by uncalcined and calcined hydrotalcite attributes mainly to the intercalation of F- into their interlayers and adsorption of F- onto their external surfaces. The fluoride removal percent of calcined hydrotalcite are higher than those of uncalcined hydrotalcite at F(initial):hydrotalcite ratios varying between 0.1 and 1.5, whereas the situation is the reverse at a ratio of 2.0 in the 30 d sorption runs. It was induced by the precipitation of fluoride-bearing nordstrandite and sellaite during a long contact of high concentration fluoride solution with uncalcined hydrotalcite. In contrast, the sorption of fluoride by uncalcined and calcined takovite occurs predominantly on their external surfaces. Fluoride-bearing gibbsite or nordstrandite and NiF2 were formed as the fluoride solutions were treated by uncalcined takovite in the 30 d runs, which enhanced its defluoridation effect. The fluoride removal efficiency of calcined takovite is much lower than uncalcined takovite and calcined hydrotalcite, because the expected restoration of original layered structure of takovite did not happen during the reaction of calcined takovite with the fluoride solution.

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

    Science.gov (United States)

    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

  18. In vivo efficacy of tamarind (Tamarindus indica) fruit extract on experimental fluoride exposure in rats.

    Science.gov (United States)

    Dey, S; Swarup, D; Saxena, Anju; Dan, Ananya

    2011-12-01

    The study was undertaken to determine the efficacy of hydro-methanolic (1:1) extract of tamarind (Tamarindus indica L.) fruit pulp in removing body fluoride burden. Thirty rats were divided into five groups. Keeping no fluoride group as the control, rats of no treatment, low dose, middle dose and high dose groups received sodium fluoride orally at the rate of 200mg per kg body weight daily for 14 weeks. Rats of low dose, middle dose and high dose group simultaneously received tamarind fruit pulp extract at three doses, viz. 25 (low), 50 (medium) and 100mg (high) per kg body weight orally, respectively. Fluoride concentration in blood, urine and long bone of experimental rats was monitored to assess the efficacy of the extract. Mean serum fluoride concentration in fluoride exposed rats was 0.145 ± 0.009 and 0.783 ± 0.042 μg/ml on days 0 and 98. In comparison, fluoride concentrations in tamarind treated rats were 0.179 ± 0.021 and 0.633 ± 0.015; 0.179 ± 0.021 and 0.502 ± 0.025 and 0.176 ± 0.021 and 0.498 ± 0.030 μg/ml in low, medium and high dose groups, respectively on day 0 and day 98 of the experiment. There was a significant (p ≤ 0.01) increase in urinary fluoride excretion from day 28 onwards. The mean fluoride concentration in long bones of treated rats was significantly lower than the values recorded in fluoride exposed rats. These findings suggest that concomitant use of tamarind fruit pulp extract can reduce fluoride concentration in blood and bone and enhanced urinary excretion, indicating the ameliorative potential of fruits of tamarind in fluoride toxicity.

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

    OpenAIRE

    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...

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

    Jelenko, Ida; Pokorny, Boštjan

    2010-12-15

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2010-05-01

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

  4. Effects of fluoride on animals and plants in the south Safi zone

    Energy Technology Data Exchange (ETDEWEB)

    Kessabi, M.; Assimi, B.; Braun, J.P.

    1984-09-01

    Fluoride pollution caused by the factories processing natural phosphates 10 km south of Safi affects animals and plants. Fluoride concentrations are 4-10 times higher in contaminated plants than in plants from the non-polluted areas. Fluoride levels of 700 ppm, 280 ppm, 75 ppm, 25 ppm, and 1.6 ppm were found in grass, forage, straw, barley caryopses and drinking water, respectively. The ingestion of polluted plants and the inhalation of fluoride (as gases and dusts) induce a high daily intake in animals which show important signs and lesions of dental fluorosis. Serious toxicity signs were also observed in plants.

  5. Fluoride concentrations in industrialized beverages consumed by children in the city of Bauru, Brazil

    Directory of Open Access Journals (Sweden)

    Carolina Simonetti Lodi

    2007-06-01

    Full Text Available The increasing consumption of juices, soft drinks and teas among children has increased significantly fluoride ingestion at the age range of risk for development of dental fluorosis. Objective: The purpose of this study was to evaluate fluoride concentrations in some brands of industrialized beverages consumed by children in the city of Bauru, SP, Brazil. Material and Methods: 98 brands of beverages were analyzed, divided into 3 lots, comprising 36, 32 and 30 brands, respectively, for the first, second and third lots. Fluoride concentrations were determined by HMDS-facilitated diffusion, using a fluoride ion-specific electrode (Orion 9409. Results: Fluoride concentrations ranged between 0.04 and 1.76 µg F/mL. It was observed a wide variation in fluoride concentrations among the different brands, as well as the different lots of the same brand. There was no information on fluoride concentrations on the labels of any product. Conclusions: Some of the products analyzed could contribute significantly to the total fluoride intake and, thus, be important risk factors for development of dental fluorosis, which indicates the need of controlling the production of these beverages with respect to fluoride concentration.

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

    Science.gov (United States)

    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.

  7. Comparison of fluoride concentration in several types of green tea consumed in Iran

    Directory of Open Access Journals (Sweden)

    S. Maleki Kambakhsh

    2016-04-01

    Full Text Available Background: Tea is known as a source of fluoride that not only can prevent tooth decay but also can increase the risk of dental fluorosis in overuse or in combination with other sources of fluoride. Objective: The aim of this study was to compare the fluoride concentration in three brands of green tea consumed in Iran. Methods: This experimental study was conducted in Qazvin University of medical Science during 2012. Three brands of green tea (bag type and packed type were evaluated. Two bags of every bag type and two 1-gram samples of every packed type were selected. Each time, the samples were placed in 100 ml distilled boiling water and were restored in an incubator at 80 ºC. Three and ten minutes after tea brewing, the fluoride concentration of filtrated water was measured by chromatography and was recorded in milligram per liter. Data were analyzed using ANOVA and repeated measures ANOVA. Findings: The fluoride concentration in bag type green tea was more than packed type. The fluoride concentration was not different among three brands of green tea. The fluoride concentration after ten minutes brewing was not significantly different from the concentration after three minutes brewing. Conclusion: With regards to the results, it seems that green tea brand and the brewing time does not affect fluoride release. The fluoride release in bag type green tea is more than packed type.

  8. Caries-­preventive Effect of 1300ppm Fluoride and Carrageenan Containing Toothpaste

    Directory of Open Access Journals (Sweden)

    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

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

    OpenAIRE

    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...

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

    KAUST Repository

    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.

  11. Fluoride Removal From Drinking Water by Electrocoagulation Using Iron and Aluminum Electrodes

    Directory of Open Access Journals (Sweden)

    Takdastan

    2014-07-01

    Full Text Available Background Existence of fluoride in drinking water above the permissible level causes human skeletal fluorosis. Objectives Electrocoagulation by iron and aluminum electrodes was proposed for removing fluoride from drinking water. Materials and Methods Effects of different operating conditions such as treatment time, initial pH, applied voltage, type and number of electrodes, the spaces between aluminum and iron electrodes, and energy consumption during electrocoagulation were investigated in the batch reactor. Variable concentrations of fluoride solution were prepared by mixing proper amounts of sodium fluoride with deionized water. Results Experimental results showed that aluminum electrode is more effective in fluoride removal than iron, as in 40 minutes and initial pH of 7.5 at 20 V, the fluoride removal process reached to 97.86%. The final recommendable limit of fluoride (1.5 mg/L was obtained in 10 minutes at 20 V with the aluminum electrode. Conclusions In electrocoagulation with iron and aluminum electrodes, increase of voltage, number of electrodes and reaction time as well as decrease of the spaces between electrodes, enhanced the fluoride removal efficiency from drinking water. In addition the effect of pH and initial concentration of fluoride varied with types of electrodes.

  12. Caffeic acid, a phyto polyphenol mitigates fluoride induced hepatotoxicity in rats: A possible mechanism.

    Science.gov (United States)

    Kanagaraj, Vishnu Vignesh; Panneerselvam, Lakshmikanthan; Govindarajan, Vimal; Ameeramja, Jaishabanu; Perumal, Ekambaram

    2015-01-01

    Fluoride induced hepatotoxicity has been extensively studied in both humans and animals. However, the mechanism underlying in the hepatotoxicity of experimental fluorosis remains obscure. The severity of fluoride toxicity was reduced by oral administration of certain plant derived antioxidants. Caffeic acid (CA) a polyphenolic compound has diverse range of pharmacological activity in the biological system. Therefore, the present study was aimed to investigate the protective mechanism of CA, against fluoride induced hepatotoxicity in rats. The rats were treated with 300 ppm of NaF via drinking water ad libitum alone and in combination with CA at a dose of 50 mg/kg daily for 30 days by oral intubation. CA treatment significantly prevented fluoride induced hepatic damage as evident from the histopathological studies and declined levels of serum fluoride and liver marker enzymes. A significant decrease in the levels of enzymatic (SOD2, CAT, GPx, and GSTpi class) and nonenzymatic (GSH and Vitamin C) antioxidants along with increased ROS, lipid peroxidation, protein carbonyl content, and nitrate levels by fluoride were also prevented in these groups. In addition, CA inhibits fluoride induced apoptosis by altering the Bax and caspase-3p20 expressions. Further, fluoride induced upregulation of Nox4, p38α MAPK, Hsp60, and downregulation of Hsp27 are the indicators for the detection of oxidative damage, apoptosis, and mitochondrial stress was also modulated by CA. These findings reveal that CA supplementation has a protective effect against fluoride induced hepatotoxicity in rats.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    Dental caries is the most prevalent chronic disease affecting human populations around the world. It is recognized that fluoride plays a significant role in dental caries reduction. Meanwhile, several low- and middle-income countries of Asia have not yet implemented systematic fluoride programs...... 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...... need further dissemination. The meeting was co-sponsored by the World Health Organization, the International Association for Dental Research, and the World Dental Federation....

  14. Effects of Fluoride on Lipid Peroxidation, DNA Damage and Apoptosis in Human Embryo Hepatocytes

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Fluoride removal from groundwater by limestone treatment in presence of phosphoric acid.

    Science.gov (United States)

    Gogoi, Sweety; Nath, Suresh K; Bordoloi, Shreemoyee; Dutta, Robin K

    2015-04-01

    Fluoride removal from groundwater has been studied by addition of dilute phosphoric acid (PA) to the influent water before limestone treatment through laboratory plug-flow column experiments and bench-scale plug-flow pilot tests. In this PA-enhanced limestone defluoridation (PAELD) technique, fluoride is removed from 0.526 mM to 0.50-52.60 μM in 3 h with near neutral final pH. The presence of PA increases the fluoride removal capacity of limestone to 1.10 mg/g compared to 0.39 mg/g reported in its absence. The changes in fluoride removal with variation in initial PA concentration, initial fluoride concentration and the final pH have been found to be statistically significant with p < 0.05. The estimated recurring cost is US$ ≈0.58/m(3) water. Simple scrubbing and rinsing is a preferable method for regeneration of limestone as it is almost equally effective with lime or NaOH. Sorption of fluoride by calcium phosphates produced in situ in the reactor is the dominant mechanism of fluoride removal in the PAELD. Precipitation of CaF2 and sorption of fluoride by the limestone also contribute to the fluoride removal. High efficiency, capacity, safety, environment-friendliness, low cost and simplicity of operation make the PAELD a potential technique for rural application.

  16. Health effects of indoor fluoride pollution from coal burning in China

    Energy Technology Data Exchange (ETDEWEB)

    Ando, M.; Tadano, M.; Asanuma, S.; Tamura, K.; Matsushima, S.; Watanabe, T.; Kondo, T.; Sakurai, S.; Ji, R.D.; Liang, C.K.; Cao, S.R. [National Institute of Environmental Studies, Osaka (Japan). Division of Regional Environment

    1998-05-01

    The combustion of high fluoride-content coal as an energy resource for heating, cooking, and food drying is a major exhaust emission source of suspended particulate matter and fluoride. High concentrations of these pollutants have been observed in indoor air of coal-burning families in some rural areas in China. Because airborne fluoride has serious toxicological properties, fluoride pollution in indoor air and the prevalence of fluorosis have been analyzed in a fluorosis area and a healthy nonfluorosis area in China and in a rural area in Japan. In the fluorosis area in China, concentrations of urinary fluoride in the residents were much higher than in the nonfluorosis area in China and in the rural area in Japan. In the fluorosis area, almost all elementary and junior high school students 10-15 years of age had dental fluorosis. Osteosclerosis in the skeletal fluorosis patients was serious. Urinary deoxypyridinoline in rural residents in China was much higher than in rural residents in Japan. Data suggest that fluoride may stimulate both bone resorption and bone formation. Because indoor fluoride from combustion of coal is easily absorbed in stored food and because food consumption is a main source of fluoride exposure, it is necessary to reduce airborne fluoride and food contamination to prevent serious fluorosis in China.

  17. Plaque growth-inhibiting effects of an abrasive fluoride-chlorhexidine toothpaste and a fluoride toothpaste containing oxidative enzymes.

    Science.gov (United States)

    Etemadzadeh, H; Ainamo, J; Murtomaa, H

    1985-08-01

    The aim of this 4 times cross-over double-blind clinical trial was to test the plaque-inhibiting effect of 2 fluoride-containing toothpastes. One toothpaste contained 0.8% chlorhexidine together with amine fluoride (0.1% F degrees) and a suitable abrasive agent. The other contained 1.7 U/g glucose oxidase and 8.0 U/g amyloglucosidase, added to an amine fluoride (0.1% F degrees) toothpaste. 1% Hibitane dental gel was used as a positive and a conventional fluoride toothpaste (Vademecum MFP Fluor) as a negative control. 9 dental students, in a randomized sequence, applied the 4 dentifrices twice daily from Monday afternoon to Friday morning with cap splints, designed to cover the teeth and about 2 mm of gingiva. No other oral hygiene measures were allowed during the 4 test periods. On Fridays, the teeth were cleaned professionally and good oral hygiene was maintained during the week-ends. At the beginning and at the end of each test period, per student plaque thickness was recorded using the plaque index, the visible plaque index, and plaque fresh weight as parameters, and the area of plaque as related to the area of the tooth surface was recorded planimetrically and according to the PLQ index. The best plaque growth-inhibiting effect was recorded for the positive control (CHX) with the test chlorhexidine toothpaste (TX) as next best. The enzyme-containing toothpaste (TE) did not differ significantly from the negative control (C). All the significant differences in anti-plaque effect between the 4 toothpastes were obtained by recordings of plaque thickness and none on the basis of area of plaque.

  18. Fluoride release and bioactivity evaluation of glass ionomer: Forsterite nanocomposite

    Directory of Open Access Journals (Sweden)

    Fatemeh Sadat Sayyedan

    2013-01-01

    Full Text Available Background: The most important limitation of glass ionomer cements (GICs is the weak mechanical properties. Our previous research showed that higher mechanical properties could be achieved by addition of forsterite (Mg 2 SiO 4 nanoparticles to ceramic part of GIC. The objective of the present study was to fabricate a glass ionomer- Mg 2 SiO 4 nanocomposite and to evaluate the effect of addition of Mg 2 SiO 4 nanoparticles on bioactivity and fluoride release behavior of prepared nanocomposite. Materials and Methods: Forsterite nanoparticles were made by sol-gel process. X-ray diffraction (XRD technique was used in order to phase structure characterization and determination of grain size of Mg 2 SiO 4 nanopowder. Nanocomposite was fabricated via adding 3wt.% of Mg 2 SiO 4 nanoparticles to ceramic part of commercial GIC (Fuji II GC. Fluoride ion release and bioactivity of nanocomposite were measured using the artificial saliva and simulated body fluid (SBF, respectively. Bioactivity of specimens was investigated by Fourier transitioned-infrared spectroscopy (FTIR, scanning electronmicroscopy (SEM, Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES and registration of the changes in pH of soaking solution at the soaking period. Statistical analysis was carried out by one Way analysis of variance and differences were considered significant if P < 0.05. Results: The results of XRD analysis confirmed that nanocrystalline and pure Mg 2 SiO 4 powder was obtained. Fluoride ion release evaluation showed that the values of released fluoride ions from nanocomposite are somewhat less than Fuji II GC. SEM images, pH changes of the SBF and results of the ICP-OES and FTIR tests confirmed the bioactivity of the nanocomposite. Statistical analysis showed that the differences between the results of all groups were significant (P < 0.05. Conclusion: Glass ionomer- Mg 2 SiO 4 nanocomposite could be a good candidate for dentistry and orthopedic

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

    Science.gov (United States)

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

    2011-08-01

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

  20. Screening biological traits and fluoride contents of native vegetations in arid environments to select efficiently fluoride-tolerant native plant species for in-situ phytoremediation.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-07-01

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

  2. Influence of heterogeneous ammonium availability on bacterial community structure and the expression of nitrogen fixation and ammonium transporter genes during in situ bioremediation of uranium-contaminated groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Mouser, P.J.; N' Guessan, A.L.; Elifantz, H.; Holmes, D.E.; Williams, K.H.; Wilkins, M.J.; Long, P.E.; Lovley, D.R.

    2009-04-01

    The impact of ammonium availability on microbial community structure and the physiological status and activity of Geobacter species during in situ bioremediation of uranium-contaminated groundwater was evaluated. Ammonium concentrations varied by as much as two orders of magnitude (<4 to 400 {micro}M) across the study site. Analysis of 16S rRNA gene sequences suggested that ammonium influenced the composition of the microbial community prior to acetate addition with Rhodoferax species predominating over Geobacter species at the site with the highest ammonium, and Dechloromonas species dominating at sites with lowest ammonium. However, once acetate was added, and dissimilatory metal reduction was stimulated, Geobacter species became the predominant organisms at all locations. Rates of U(VI) reduction appeared to be more related to the concentration of acetate that was delivered to each location rather than the amount of ammonium available in the groundwater. In situ mRNA transcript abundance of the nitrogen fixation gene, nifD, and the ammonium importer gene, amtB, in Geobacter species indicated that ammonium was the primary source of nitrogen during in situ uranium reduction, and that the abundance of amtB transcripts was inversely correlated to ammonium levels across all sites examined. These results suggest that nifD and amtB expression by subsurface Geobacter species are closely regulated in response to ammonium availability to ensure an adequate supply of nitrogen while conserving cell resources. Thus, quantifying nifD and amtB expression appears to be a useful approach for monitoring the nitrogen-related physiological status of Geobacter species in subsurface environments during bioremediation. This study also emphasizes the need for more detailed analysis of geochemical/physiological interactions at the field scale, in order to adequately model subsurface microbial processes.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. CRYSTALLIZATION KINETICS OF AMMONIUM PERCHLORATE IN AN AGITATED VESSEL

    Directory of Open Access Journals (Sweden)

    Nahidh Kaseer

    2013-05-01

    Full Text Available 31Overall crystal growth kinetics for ammonium perchlorate in laboratory scale batch  agitated vessel crystallizer have been determined from batch experiments performed in an integral mode. The effects of temperature between 30-60ºC, seed size 0.07, 0.120 and 0.275 mm and stirrer speed 160, 340, and 480 rpm, on the kinetics of crystal growth were investigated. Two different methods, viz. polynomial fitting and initial derivative were used to predict the kinetics expression. In general both methods gave comparable results for growth kinetics estimation. The order of growth process is not more than two. The activation energy for crystal growth of ammonium perchlorate was determined and found  to be equal to 5.8 kJ/ mole.            Finally, the influence of the affecting parameters on the crystal growth rate gives general expression that had an obvious dependence of the growth rate on each variables of concern (temperature, seed size, and stirrer speed .The general overall growth rate expression had shown that super saturation is the most significant variable. While the positive dependence of the stirrer speed demonstrates the importance of the diffusional step in the growth rate model. Moreover, the positive dependence of the seed size demonstrate the importance of the surface integration  step in the growth rate model. All the studied variables tend to suggest that the growth rate characteristics  of ammonium perchlorate from aqueous solution commenced in a batch crystallizer are diffusion kinetic controlled process.

  5. Enhancement of luminescence in white emitting strontium fluoride core @ calcium fluoride shell nanoparticles.

    Science.gov (United States)

    Kumam, Nandini; Singh, Ningthoujam Premananda; Singh, Laishram Priyobarta; Srivastava, Sri Krishna

    2015-12-01

    Synthesis of lanthanide-doped fluoride SrF2:3Dy and SrF2:3Dy@CaF2 nanoparticles with different ratios of core to shell (1:0.5, 1:1 and 1:2) has been carried out by employing ethylene glycol route. X-ray diffraction (XRD) patterns reveal that the structure of the prepared nanoparticles was of cubical shape, which is also evident in TEM images. The size of the nanoparticles for core (SrF2:3Dy) is found to increase when core is covered by shell (CaF2). It is also evident from Fourier transform infrared spectroscopy (FTIR) that ethylene glycol successfully controls the growth and acts as a shape modifier by regulating growth rate. In the photoluminescence investigation, emission spectra of SrF2:3Dy is found to be highly enhanced when SrF2:3Dy is covered by CaF2 due to the decrease of cross relaxation amongst the Dy(3+)-Dy(3+) ions. Such type of enhancement of luminescence in homonanostructure SrF2:3Dy@CaF2 (core@shell) has not been studied so far, to the best of the authors' knowledge. This luminescent material exhibits prominently white light emitting properties as shown by the Commission Internationale d'Eclairage (CIE) chromaticity diagram. The calculated correlate colour temperature (CCT) values for SrF2:3Dy, SrF2:3Dy@CaF2 (1:0.05), SrF2:3Dy@CaF2 (1:1) and SrF2:3Dy@CaF2 (1:2) are 5475, 5476, 5384 and 5525 K, respectively, which lie in the cold white region. Graphical abstract White light emitting homonanostructure material SrF2:3Dy@CaF2(core@shell).

  6. The Properties of Ammonium Dinitramine (ADN): Part 2: Melt Casting

    Science.gov (United States)

    Hahma, A.; Edvinsson, H.; Östmark, H.

    2010-04-01

    A melt casting technique for ammonium dinitramine (ADN) and ADN/aluminum was developed. ADN proved relatively easy to cast, when 1% of magnesium oxide was used as a stabilizer and crystallization kernels. Densities of ADN/MgO 99/1 were 92 to 97% of theoretical mean density (TMD) and those of ADN/Al/MgO 64/35/1 were between 95 and 99% of TMD. Sedimentation of Al in the melt was prevented and the particle wetting was ensured by selecting a suitable particle size for Al. No gelling agents or other additives were used. The casting process and factors influencing it are discussed.

  7. Surge ammonium uptake in macroalgae from a coral atoll

    Digital Repository Service at National Institute of Oceanography (India)

    Raikar, V.; Wafar, M.V.M.

    Maintenance of high levels of biological productivity (up to several gC m-2 d-1) (Crossland et al., 1991) by coral atolls in oligotrophic oceanic waters with low ambient concentrations of N nutrients (typically of the order of few hundreds of nmols..., fish shoals migrating onto the reef could raise ambient ammonium concentrations in the vicinity of corals up to 0.9 ? M (Meyer et al., 1983) and area-specific N regeneration by actively feeding holothurians (Uthicke and Klumpp, 1998) could be in a...

  8. Further laboratory and theoretical investigations of ammonium dinitramide

    Energy Technology Data Exchange (ETDEWEB)

    Tulis, A.J.; Snelson, A. [IIT Research Institut, Chicago (United States); Heberlein, C.; Patel, D.L. [U.S. Army Cecom RD et E Center, NVESD (United States)

    1996-12-31

    Hydrogen and deuterated ammonium dinitramide have been vaporized under high vacuum and the IR matrix isolation spectra of the decomposition products obtained. Tentative vibration assignments have been made for HN(NO{sub 2}){sub 2} and DN(NO{sub 2}){sub 2} assuming a symmetrical non-planar structure in which the H or D is bonded to the central nitrogen atom. Other structures are also possible. Ab initio calculations have been made for the various structural isomers of hydrogen dinitramide. Vibration frequencies calculated for the hydrogenated and deuterated species are compared with the experimental values with the object of identifying the molecules` structure. (authors) 3 refs.

  9. Experimental study of the detonation of technical grade ammonium nitrate

    Science.gov (United States)

    Presles, Henri-Noël; Vidal, Pierre; Khasainov, Boris

    2009-11-01

    The detonation of technical grade ammonium nitrate at the density ρ=0.666 g/cm confined in PVC and steel tubes was experimentally studied. The results show that the detonation is self-sustained and steady in steel tubes with diameter as small as 12 mm. Critical detonation diameter lies between 8 and 12 mm in 2 mm thick steel tubes and between 55 and 81 mm in PVC tubes. These values testify a strong detonation sensitivity of this product. To cite this article: H.-N. Presles et al., C. R. Mecanique 337 (2009).

  10. Ammonium diamminesilver(I bis(5-chloro-2-hydroxybenzenesulfonate trihydrate

    Directory of Open Access Journals (Sweden)

    Zhao-Peng Deng

    2012-02-01

    Full Text Available The reaction of silver nitrate with 5-chloro-2-hydroxybenzenesulfonic acid in the presence of ammonia yielded the title salt, (NH4[Ag(NH32](C6H4ClO4S2·3H2O. The AgI ion shows linear coordination [N—Ag—N = 175.2 (1 °]. The ammonium and diamminesilver cations, the benzenesulfonate anion and the lattice water molecules interact through an intricate network of N—H...O and O—H...O hydrogen bonds to form a three-dimensional network.

  11. Fluoride influences nickel-titanium orthodontic wires' surface texture and friction resistance

    Science.gov (United States)

    Abbassy, Mona Aly

    2016-01-01

    Objectives: The aim of this study was to investigate the effects exerted by the acidulated fluoride gel on stainless steel and nickel-titanium (Ni-Ti) orthodontic wires. Materials and Methods: Sixty stainless steel and Ni-Ti orthodontic archwires were distributed into forty archwires used for in vitro study and twenty for in situ study. Fluoride was applied for 1 h in the in vitro experiment while it was applied for 5 min in the in situ experiment. The friction resistance of all wires with ceramic brackets before/after topical fluoride application was measured using a universal testing machine at 1 min intervals of moving wire. Moreover, surface properties of the tested wires before/after fluoride application and before/after friction test were examined by a scanning electron microscope (SEM). Dunnett's t-test was used to compare frictional resistance of as-received stainless steel wires and Ni-Ti wires to the wires treated by fluoride in vitro and in situ (P < 0.05). Two-way ANOVA was used to compare the effect of fluoride application and type of wire on friction resistance in vitro and in situ (P < 0.05). Results: Ni-Ti wires recorded significantly high friction resistance after fluoride application when compared to stainless steel wires in vitro, P < 0.05. Fluoride application did not significantly affect the friction resistance of the tested wires in situ, P < 0.05. SEM observation revealed deterioration of the surface texture of the Ni-Ti wires after fluoride application in vitro and in situ. Conclusions: The in vitro fluoride application caused an increase in friction resistance of Ni-Ti wires when compared to stainless steel wires. In vitro and in situ fluoride application caused deterioration in surface properties of Ni-Ti wires. PMID:27843886

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Matrix supported tailored polymer for solid phase extraction of fluoride from variety of aqueous streams

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Neha; Kumar, Sanjukta A.; Wagh, D.N. [Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Das, Sadananda; Pandey, Ashok K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Kumar, Sangita D., E-mail: sangdk@barc.gov.in [Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Reddy, A.V.R. [Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2012-01-30

    Highlights: Black-Right-Pointing-Pointer Th complexed with poly (bis[2-(methacryloyloxy)-ethyl]phosphate) as tailored polymer membranes. Black-Right-Pointing-Pointer Membranes offered high capacity and selectivity for fluoride in aqueous media. Black-Right-Pointing-Pointer Quantitative uptake (80 {+-} 5%) of fluoride. Black-Right-Pointing-Pointer Fast sorption kinetics. Black-Right-Pointing-Pointer Reusability of polymer membranes. - Abstract: Fluoride related health hazards (fluorosis) are a major environmental problem in many regions of the world. It affects teeth; skeleton and its accumulation over a long period can lead to changes in the DNA structure. It is thus absolutely essential to bring down the fluoride levels to acceptable limits. Here, we present a new inorganic-organic hybrid polymer sorbent having tailored fixed-sites for fluoride sorption. The matrix supported poly (bis[2-(methacryloyloxy)-ethyl]phosphate) was prepared by photo-initiator induced graft-polymerization in fibrous and microporous (sheet) host poly(propylene) substrates. These substrates were conditioned for selective fluoride sorption by forming thorium complex with phosphate groups on bis[2-methacryloyloxy)-ethyl] phosphate (MEP). These tailored sorbents were studied for their selectivity towards fluoride in aqueous media having different chemical conditions. The fibrous sorbent was found to take up fluoride with a faster rate (15 min for Almost-Equal-To 76% sorption) than the sheet sorbent. But, the fluoride loading capacity of sheet sorbent (4320 mg kg{sup -1}), was higher than fibrous and any other sorbent reported in the literature so far. The sorbent developed in the present work was found to be reusable after desorption of fluoride using NaOH solution. It was tested for solid phase extraction of fluoride from natural water samples.

  15. Analysis of the Role of Insulin Signaling in Bone Turnover Induced by Fluoride.

    Science.gov (United States)

    Liu, Qinyi; Liu, Hui; Yu, Xiuhua; Wang, Yan; Yang, Chen; Xu, Hui

    2016-06-01

    The role of insulin signaling on the mechanism underlying fluoride induced osteopathology was studied. We analyzed the expression of genes related with bone turnover and insulin signaling in rats treated by varying dose of fluoride with or without streptozotocin (STZ) in vivo. Furthermore, insulin receptor (InR) expression in MC3T3-E1 cells (pre-osteoblast cell line) was interfered with small interfering RNA (siRNA), and genes related with osteoblastic and osteoclastic differentiation were investigated in cells exposed to fluoride in vitro for 2 days. The in vivo study indicated the possible role of insulin in bone lesion induced by excessive amount of fluoride. Fluoride activated the InR and Insulin-like growth factor 1 (IGF1) signaling, which were involved in the mechanism underlying fluoride induced bone turnover. The TGFβ1 and Wnt10/β-catenin pathway took part in the mechanism of bone lesion induced by fluoride, and insulin probably modulated the TGFβ1 and β-catenin to exert action on bone turnover during the development of bone lesion. The in vitro study showed the concomitant decrease of OPG, osterix and OCN with inhibition of InR expression in osteoblast, and three genes still was low in cells co-treated with fluoride and InR siRNA, which suggested that fluoride probably stimulated the expression of OPG, osterix and OCN through InR signaling. In conclusion, insulin played the important role in bone lesion induced by excessive amount of fluoride through mediating InR receptor signaling, and IGF1 signaling probably exerted action on bone turnover caused by overdose of fluoride.

  16. Determination of ammonium bifluoride and ammonium fluoride in mixture by dual-indicator combined formaldehyde method%双指示剂结合甲醛法分步测定氟化氢铵及氟化铵

    Institute of Scientific and Technical Information of China (English)

    李贺军; 张承屏

    2014-01-01

    基于甲醛法无法准确测定氟化氢铵产品中氟化铵杂质的缺点,用双指示剂法对甲醛法进行改进.先以中性红-溴百里酚蓝为指示剂滴定溶液氟化氢铵的含量,再用酚酞为指示剂甲醛法测溶液中总NH4+量从而得出氟化铵含量,由此可实现氟化氢铵及其中氟化铵含量的分别测定.该方法操作简单,准确度高,加标回收率为99.7%~ 101.0%,最大相对偏差在±2.0%左右,具有较高的实用性.

  17. Controlling Magnetic and Ferroelectric Order Through Geometry: Synthesis, Ab Initio Theory, Characterization of New Multi-Ferric Fluoride Materials

    Energy Technology Data Exchange (ETDEWEB)

    Halasyamani, Shiv [Univ. of Houston, TX (United States); Fennie, Craig [Cornell Univ., Ithaca, NY (United States)

    2016-11-03

    We have focused on the synthesis, characterization, and ab initio theory on multi-functional mixed-metal fluorides. With funding from the DOE, we have successfully synthesized and characterized a variety of mixed metal fluoride materials.

  18. Biological removal of selenate and ammonium by activated sludge in a sequencing batch reactor.

    Science.gov (United States)

    Mal, J; Nancharaiah, Y V; van Hullebusch, E D; Lens, P N L

    2017-04-01

    Wastewaters contaminated by both selenium and ammonium need to be treated prior to discharge into natural water bodies, but there are no studies on the simultaneous removal of selenium and ammonium. A sequencing batch reactor (SBR) was inoculated with activated sludge and operated for 90days. The highest ammonium removal efficiency achieved was 98%, while the total nitrogen removal was 75%. Nearly a complete chemical oxygen demand removal efficiency was attained after 16days of operation, whereas complete selenate removal was achieved only after 66days. The highest total Se removal efficiency was 97%. Batch experiments showed that the total Se in the aqueous phase decreased by 21% with increasing initial ammonium concentration from 50 to 100mgL(-1). This study showed that SBR can remove both selenate and ammonium via, respectively, bioreduction and partial nitrification-denitrification and thus offer possibilities for treating selenium and ammonium contaminated effluents.

  19. Fluoride Release From Three Different Types of Giass- lonomer Cements After Exposure to Acidic and Neutral NaF Solution

    Directory of Open Access Journals (Sweden)

    Kousari A

    2000-06-01

    Full Text Available The purpose of this study was to assess the fluoride release of three fluoride- containing materials exposed to fluoride solutions. This study compared the initial fluoride release and release following re-fluoridation (neutral or acidic 2% NaF of three different filling materials, conventional glass ionomer cement (CG1C, resin- modified glass ionomer cement (RMGIC, polyacid- modified composite resin (PAMCR. Twenty discs of each material, measuring 2mm height and 6mm diameter, were suspended in separate vials of 2" laboratory artificial saliva. The amount of fluoride release was measured over two periods of 28 days each. Fluoride release was determined at 1,3,7,14 and 28 days of each period. Fluoride was measured with a fluoride ion- specific electrode and an ion analyzer previously calibrated with standard solution .T- test and ANOVA were used to evaluate the data. Fluoride release for all products at days 1 and 3 was significantly greater than the rest of the time intervals. Then, the fluoride release decreased significantly. CGIC released significantly more fluoride than the other products. This was followed by RMGIC, which exhibited significantly more fluoride release than PAMCR. In second period of experiment, the specimens were assigned to two subgroups often each. The samples exposed to two different solution of NaF (neutral or acidic. All groups showed the capacity of re-fluoridation and fluoride uptake. The specimens exposed to acidic NaF solution showed statistically more significant rechargeability than the neutral NaF solution. It may be concluded that glass ionomer cements act as a rechargeable slow fluoride release systems and as an effective caries preventive material in caries preventing programs for caries susceptible children.

  20. Relations of ammonium minerals at several hydrothermal systems in the western U.S.

    Science.gov (United States)

    Krohn, M. Dennis; Kendall, Carol; Evans, John R.; Fries, Terry L.

    1993-08-01

    Ammonium bound to silicate and sulfate minerals has recently been located at several major hydrothermal systems in the western U.S. utilizing newly-discovered near-infrared spectral properties. Knowledge of the origin and mineralogic relations of ammonium minerals at known hydrothermal systems is critical for the proper interpretation of remote sensing data and for testing of possible links to mineralization. Submicroscopic analysis of ammonium minerals from two mercury- and gold-bearing hot-springs deposits at Ivanhoe, Nevada and McLaughlin, California shows that the ammonium feldspar, buddingtonite, occurs as fine-grained euhedral crystals coating larger sulfide and quartz crystals. Ammonium feldspar seems to precipitate relatively late in the crystallization sequence and shows evidence for replacement of NH 4 + by K + or other monovalent cations. Some buddingtonite is observed in close association with mercury, but not with gold. Ammonioalunite is found in a variety of isolated crystal forms at both deposits. Nitrogen isotopic values for ammonium-bearing minerals show a 14‰ range in composition, precluding assignment of a specific provenance to the nitrogen. The correlations of nitrogen isotopic values with depth and ammonium content suggest some loss of nitrogen in the oxidizing supergene environment, possibly as a metastable mineral. The high ammonium content in these hydrothermal systems, the close association to mercury, and the small crystal size of the ammonium-bearing minerals all suggest that ammonium may be transported in a late-stage vapor phase or as an organic volatile. Such a process could lead to the formation of a non-carbonaceous organic aureole above a buried geothermal source. The discovery of a 10-km outcrop of ammonium minerals confirms that significant substitution of ammonium in minerals is possible over an extensive area and that remote sensing is a feasible means to detect such aureoles.