WorldWideScience

Sample records for mercury fluorides

  1. Mercury

    International Nuclear Information System (INIS)

    Vilas, F.; Chapman, C.R.; Matthews, M.S.

    1988-01-01

    Papers are presented on future observations of and missions to Mercury, the photometry and polarimetry of Mercury, the surface composition of Mercury from reflectance spectrophotometry, the Goldstone radar observations of Mercury, the radar observations of Mercury, the stratigraphy and geologic history of Mercury, the geomorphology of impact craters on Mercury, and the cratering record on Mercury and the origin of impacting objects. Consideration is also given to the tectonics of Mercury, the tectonic history of Mercury, Mercury's thermal history and the generation of its magnetic field, the rotational dynamics of Mercury and the state of its core, Mercury's magnetic field and interior, the magnetosphere of Mercury, and the Mercury atmosphere. Other papers are on the present bounds on the bulk composition of Mercury and the implications for planetary formation processes, the building stones of the planets, the origin and composition of Mercury, the formation of Mercury from planetesimals, and theoretical considerations on the strange density of Mercury

  2. 199Hg Moessbauer measurements on mercury, alloys and Hg-fluorides

    International Nuclear Information System (INIS)

    Wurtinger, W.; Kankeleit, E.

    1979-01-01

    The Moessbauer effect on the 158 keV 5/2 - -1/2 - transition in 199 Hg, of the order of 10 ppm, has been studied using the current integration technique. The isomer shift between the Hg(I)- and Hg(II)-fluorides as well as the quadrupole splitting in Hg 2 Pt and Hg 2 F 2 are interpreted in terms of relativistic Hartree-Fock-Slater and Molecular Orbital calculations. The following nuclear parameters could be derived: Δ[r 2 ] = (3.2+-1.1) 10 -3 fm 2 and Q(5/2 - ) = (-0.8+-0.4)b. Evidence for an oblate triaxially deformed 199 Hg nucleus is derived from particle plus rotor calculations. (orig.)

  3. Mercury

    NARCIS (Netherlands)

    de Vries, Irma

    2017-01-01

    Mercury is a naturally occurring metal that exists in several physical and chemical forms. Inorganic mercury refers to compounds formed after the combining of mercury with elements such as chlorine, sulfur, or oxygen. After combining with carbon by covalent linkage, the compounds formed are called

  4. Mercury

    Science.gov (United States)

    ... build up in fish, shellfish, and animals that eat fish. The nervous system is sensitive to all forms of mercury. Exposure to high levels can damage the brain and kidneys. Pregnant women can pass the mercury in their bodies to their babies. It is important to protect your family from ...

  5. Mercury

    Science.gov (United States)

    ... has set a limit of 2 parts of mercury per billion parts of drinking water (2 ppb). The Food and Drug Administration (FDA) has set a maximum permissible level of 1 part of methylmercury in a million ... of 0.1 milligram of organic mercury per cubic meter of workplace air (0.1 ...

  6. Mercury

    CERN Document Server

    Balogh, André; Steiger, Rudolf

    2008-01-01

    Mercury, the planet closest to the Sun, is different in several respects from the other three terrestrial planets. In appearance, it resembles the heavily cratered surface of the Moon, but its density is high, it has a magnetic field and magnetosphere, but no atmosphere or ionosphere. This book reviews the progress made in Mercury studies since the flybys by Mariner 10 in 1974-75, based on the continued research using the Mariner 10 archive, on observations from Earth, and on increasingly realistic models of its interior evolution.

  7. Fluoride and fluoridation.

    Science.gov (United States)

    Smith, G E

    1988-01-01

    To date, many of the ways of controlling tooth decay involve the use of fluorides. Either systemically via fluoridated water and tablets, or, topically, with fluoride-containing toothpaste and mouthrinses. There is now evidence that the prevalence of dental caries is declining in communities with unfluoridated water, as well as in those with fluoridated water. This phenomenon may be related to an increase of fluoride in the food chain; the unintentional ingestion of fluoride-containing dental health products; and the increasing contamination of the total environment with fluoride emissions and solid wastes from many industries. The apparent usefulness of fluoride as a preventive against dental caries does not mean that unnecessary exposure to the element should be tolerated. Fluoride at very low concentrations is phytotoxic and harmful to livestock; and in man, excessive intakes of fluoride over many years may lead to a well-defined disorder--skeletal fluorosis. In addition, a number of recent studies have suggested that fluoride may be genotoxic.

  8. Fluoridated Water

    Science.gov (United States)

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

  9. Spectrophotometric determination of fluoride in drinking water using ...

    African Journals Online (AJOL)

    2011-03-14

    Mar 14, 2011 ... A sensitive spectrophotometric determination of fluoride in drinking water has been developed using aluminium complexes ... Keywords: Fluoride analysis, spectrophotometric method, drinking water, aluminium triphenylmethane dye ..... mechanism at the mercury electrode in neutral and alkaline aque-.

  10. Fluoridation Basics

    Science.gov (United States)

    ... Water Today The mineral fluoride occurs naturally on earth and is released from rocks into the soil, ... where your state ranks in percent of the population that receives water with fluoride . Cost: Saves Money, ...

  11. Scandium fluorides

    International Nuclear Information System (INIS)

    Melnikov, P.; Nalin, M.; Messaddeq, Y.

    1997-01-01

    A new modification of scandium fluoride has been synthesised. The compound is deficient in fluorine, with the composition ScF 2.76 . It belongs to the tetragonal system, lattice parameters being a=3.792 and c=6.740 A and may be obtained at low temperatures by the decomposition of the precursor NH 4 ScF 4 . The reaction is topotactic, tetragonal parameters of the precursor are a=4.021 and c=6.744 A. Structural relationships with various fluorides and ammonium aminofluorides are discussed. This synthesis route with IR-assisted decomposition should be considered as a soft-chemistry approach. (orig.)

  12. Bottled Water and Fluoride

    Science.gov (United States)

    ... What's this? Submit What's this? Submit Button 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, ...

  13. Fluoride Nanoscintillators

    Directory of Open Access Journals (Sweden)

    Luiz G. Jacobsohn

    2011-01-01

    Full Text Available A preliminary investigation of the scintillation response of rare earth-doped fluoride nanoparticles is reported. Nanoparticles of CaF2 : Eu, BaF2 : Ce, and LaF3 : Eu were produced by precipitation methods using ammonium di-n-octadecyldithiophosphate (ADDP as a ligand that controls growth and lessens agglomeration. The structure and morphology were characterized by means of X-ray diffraction and transmission electron microscopy, while the scintillation properties of the nanoparticles were determined by means of X-ray and 241Am irradiation. The unique aspect of scintillation of nanoparticles is related to the migration of carriers in the nanoscintillator. Our results showed that even nanoparticles as small as ~4 nm in size effectively scintillate, despite the diffusion length of e-h pairs being considerably larger than the nanoparticles themselves, and suggest that nanoparticles can be used for radiation detection.

  14. Other Fluoride Products

    Science.gov (United States)

    ... Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States . MMWR , August 17, 2001; ... informed of both the benefit of protection against tooth decay and the possibility of dental fluorosis. Fluoride Gel and Foam Form Fluoride gel ...

  15. 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

  16. Mercury and Your Health

    Science.gov (United States)

    ... the Risk of Exposure to Mercury Learn About Mercury What is Mercury What is Metallic mercury? Toxicological Profile ToxFAQs Mercury Resources CDC’s National Biomonitoring Program Factsheet on Mercury ...

  17. Got Mercury?

    Science.gov (United States)

    Meyers, Valerie E.; McCoy, J. Torin; Garcia, Hector D.; James, John T.

    2009-01-01

    Many of the operational and payload lighting units used in various spacecraft contain elemental mercury. If these devices were damaged on-orbit, elemental mercury could be released into the cabin. Although there are plans to replace operational units with alternate light sources, such as LEDs, that do not contain mercury, mercury-containing lamps efficiently produce high quality illumination and may never be completely replaced on orbit. Therefore, exposure to elemental mercury during spaceflight will remain possible and represents a toxicological hazard. Elemental mercury is a liquid metal that vaporizes slowly at room temperature. However, it may be completely vaporized at the elevated operating temperatures of lamps. Although liquid mercury is not readily absorbed through the skin or digestive tract, mercury vapors are efficiently absorbed through the respiratory tract. Therefore, the amount of mercury in the vapor form must be estimated. For mercury releases from lamps that are not being operated, we utilized a study conducted by the New Jersey Department of Environmental Quality to calculate the amount of mercury vapor expected to form over a 2-week period. For longer missions and for mercury releases occurring when lamps are operating, we conservatively assumed complete volatilization of the available mercury. Because current spacecraft environmental control systems are unable to remove mercury vapors, both short-term and long-term exposures to mercury vapors are possible. Acute exposure to high concentrations of mercury vapors can cause irritation of the respiratory tract and behavioral symptoms, such as irritability and hyperactivity. Chronic exposure can result in damage to the nervous system (tremors, memory loss, insomnia, etc.) and kidneys (proteinurea). Therefore, the JSC Toxicology Group recommends that stringent safety controls and verifications (vibrational testing, etc.) be applied to any hardware that contains elemental mercury that could yield

  18. Fluoride and Oral Health.

    Science.gov (United States)

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

    2016-06-01

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

  19. [Fluoride release in children's toothpastes].

    Science.gov (United States)

    Sättler, M; Hanfland, D; Wetzel, W E

    1993-01-01

    Comparative investigations of six toothpastes for children obtainable on the German market were carried out to determine their bioavailable fluoride concentration in vitro and in vivo. Four products contained sodium monofluorophosphate, one sodium fluoride and another amine fluoride. The product containing sodium fluoride had, both in the toothpaste-saliva-mixture in the test-tube as well as in the aquadest-toothpaste-saliva-mixture, derived from the oral cavity the maximum proportion of dissolved fluoride (> 70%). The product containing amine fluoride still had > 45% of free fluoride, the sodium monofluorophosphate products however had 10% or less of free fluoride.

  20. Basic Information about Mercury

    Science.gov (United States)

    ... Your Environment Contact Us Share Basic Information about Mercury On this page: What is mercury? Emissions of ... Consumer products that traditionally contain mercury What is Mercury? Mercury is a naturally-occurring chemical element found ...

  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...... (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...

  2. 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

  3. fluoride iontophoresis versus topical fluoride application

    African Journals Online (AJOL)

    The process of influencing ionic motion by electrical cur- rent has been termed iontophoresis, electophoresis ... In iontophroresis, it is believed that fluoride ion is elec- trically driven deeper into the dentinal tubules. ..... the hydraulic conductance of Human Dentin, in vitro, J. Dent. Res. 1981; 60:686698. 6. Gillam D G. Clinical ...

  4. Preparation of bromine fluoride

    International Nuclear Information System (INIS)

    Domange, Pr; Duflo, J.

    1958-05-01

    This note addresses the preparation of bromine fluoride. It indicates the implemented process for the reaction, used products (fluorine and bromine), and column characteristics. It describes the operating mode. Apparatus drawing is provided

  5. 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...

  6. Mercury and Pregnancy

    Science.gov (United States)

    ... Home > Pregnancy > Is it safe? > Mercury and pregnancy Mercury and pregnancy E-mail to a friend Please ... vision problems. How can you be exposed to mercury? Mercury has several forms: It can be a ...

  7. 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...

  8. 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...

  9. Private Well Water and Fluoride

    Science.gov (United States)

    ... than the recommended level of fluoride for preventing tooth decay? The recommended fluoride level in drinking water for ... are higher than the recommended level for preventing tooth decay? In some regions in the United States, community ...

  10. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    Science.gov (United States)

    Barton, C.J.; Grimes, W.R.

    1960-01-01

    Molten-salt reactor fuel compositions consisting of mixtures of fluoride salts are reported. In its broadest form, the composition contains an alkali fluoride such as sodium fluoride, zirconium tetrafluoride, and a uranium fluoride, the latter being the tetrafluoride or trifluoride or a mixture of the two. An outstanding property of these fuel compositions is a high coeffieient of thermal expansion which provides a negative temperature coefficient of reactivity in reactors in which they are used.

  11. 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...

  12. Fluoride resistance in Streptococcus mutans

    NARCIS (Netherlands)

    Liao, Ying

    2017-01-01

    Fluoride has been used as the most effective anti-caries agent for over five decades. It functions not only on the dental hard tissues, but also as an antimicrobial agent. It is known that oral bacteria are able to develop resistance to fluoride, which may affect the effectiveness of fluoride in

  13. 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

    BACKGROUND: The efficacy and safety of combined use of topical fluoride products are essential issues that must be monitored. AIM: To assess urinary excretion of fluoride after application of two different dental varnishes containing 2.26% fluoride in 3- to 4-year-old children and to compare...... the levels with and without parallel use of fluoride toothpaste. 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....... After a 1-week run-in period, 0.1 mL of the two fluoride varnishes (Duraphat and Profluorid Varnish) was topically applied in a randomized order. Baseline and experimental urine was collected during 6-h periods. The fluoride content was determined with an ion-sensitive electrode. RESULTS...

  14. Magnetic interactions through fluoride

    DEFF Research Database (Denmark)

    Pedersen, Kasper Steen; Sigrist, Marc; Weihe, Høgni

    2014-01-01

    The nature of the magnetic interaction through fluoride in a simple, dinuclear manganese(III) complex (1), bridged by a single fluoride ion in a perfectly linear fashion, is established by experiment and density functional theory. The magnitude of the antiferromagnetic exchange interaction...... and the manganese(III) zero-field-splitting parameters are unambiguously determined by inelastic neutron scattering to yield J = 33.0(2) cm(-1) (Ĥ = JŜ1·Ŝ2 Hamiltonian definition) and single-ion D = -4.0(1) cm(-1). Additionally, high-field, high-frequency electron paramagnetic resonance and magnetic measurements...

  15. Small Molecule Fluoride Toxicity Agonists

    Science.gov (United States)

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

    2015-01-01

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

  16. 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.

  17. Salt fluoridation and oral health.

    Science.gov (United States)

    Marthaler, Thomas M

    2013-11-01

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

  18. Mercury's Messenger

    Science.gov (United States)

    Chapman, Clark R.

    2004-01-01

    Forty years after Mariner 2, planetary exploration has still only just begun, and many more missions are on drawing boards, nearing the launch pad, or even en route across interplanetary space to their targets. One of the most challenging missions that will be conducted this decade is sending the MESSENGER spacecraft to orbit the planet Mercury.…

  19. Mercury Report-Children's exposure to elemental mercury

    Science.gov (United States)

    ... gov . Mercury Background Mercury Report Additional Resources Mercury Report - Children's Exposure to Elemental Mercury Recommend on Facebook ... I limit exposure to mercury? Why was the report written? Children attending a daycare in New Jersey ...

  20. Comparison of Fluoridated Miswak and Toothbrushing with Fluoridated Toothpaste on Plaque Removal and Fluoride Release.

    Science.gov (United States)

    Baeshen, Hosam; Salahuddin, Sabin; Dam, Robel; Zawawi, Khalid H; Birkhed, Dowen

    2017-04-01

    Dental caries and periodontal diseases are all induced by oral biofilm (dental plaque). This study was conducted to evaluate if fluoride-impregnated miswak is as effective in plaque removal and fluoride release as toothbrushing with fluoride toothpaste. This single-blind, randomized, crossover study was conducted at the Department of Cariology, University of Gothenburg, Gothenburg, Sweden, from February 2010 to January 2011. Fifteen healthy subjects participated in this study. The participants were instructed to use the following: (1) 0.5% NaF-impregnated miswak, (2) nonfluoridated miswak, (3) toothbrush with nonfluoride toothpaste, and (4) toothbrush with 1450 ppm fluoride toothpaste. Each method was used twice a day for 1 week after which plaque amount and fluoride concentration in resting saliva were measured. There was a 1-week washout period between each method. No significant difference between miswak and tooth-brushing was found regarding plaque removal on buccal and lingual surfaces. A somewhat higher fluoride concentration in resting saliva was found after using impregnated miswak when compared with toothbrushing with fluoride toothpaste (p toothbrushing showed the same plaque removing effect on buccal and lingual surfaces. Miswak impregnated with 0.5% NaF resulted in a higher concentration of fluoride in saliva than brushing with 1450 ppm fluoride toothpaste. Miswak impregnated with 0.5% NaF and toothbrushing results in comparable plaque removal and about the same fluoride concentration in saliva even it was somewhat higher for impregnated miswak.

  1. Physiology and toxicity of fluoride

    Directory of Open Access Journals (Sweden)

    Dhar Vineet

    2009-01-01

    Full Text Available Fluoride has been described as an essential element needed for normal development and growth of animals and extremely useful for human beings. Fluoride is abundant in the environment and the main source of fluoride to humans is drinking water. It has been proved to be beneficial in recommended doses, and at the same time its toxicity at higher levels has also been well established. Fluoride gets accumulated in hard tissues of the body and has been know to play an important role in mineralization of bone and teeth. At high levels it has been known to cause dental and skeletal fluorosis. There are suggested effects of very high levels of fluoride on various body organs and genetic material. The purpose of this paper is to review the various aspects of fluoride and its importance in human life.

  2. Magnesium fluoride recovery method

    International Nuclear Information System (INIS)

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

    1989-01-01

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

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

    Science.gov (United States)

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

    2014-08-01

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

  4. Environmental mercury problem

    Energy Technology Data Exchange (ETDEWEB)

    D' Itri, F.M.

    1972-01-01

    The urgent need to eliminate or greatly reduce the discharge of mercury into the environment is paramount to the health and well being of man. That all forms of mercury are hazardous is widely recognized, but what is more devastating to our society is that all forms of mercury appear to have the potential to be converted in to highly toxic monomethylmercury, or dimethylmercury. This paper examined the historical uses of mercury, the background concentrations of mercury, the analytical methods for the determination of mercury, the contamination of the food chain by mercury, the biological methylation of mercury, the decontamination and restoration of mercury polluted areas, the epidemiology and toxicology of mercury, and the chronology of the world's mercury poisoning problem.

  5. Fluoride Content in Alcoholic Drinks.

    Science.gov (United States)

    Goschorska, Marta; Gutowska, Izabela; Baranowska-Bosiacka, Irena; Rać, Monika Ewa; Chlubek, Dariusz

    2016-06-01

    The aim of the study was to determine the role of alcoholic drinks as a potential source of dietary fluoride by means of measuring fluoride levels in selected alcoholic drinks available on the Polish market that are also diverse in terms of the percentage content of ethanol. The study was conducted on 48 types of drinks with low, medium, and high alcohol content available on the Polish market and offered by various manufacturers, both Polish and foreign. Fluoride concentrations in individual samples were measured by potentiometric method with a fluoride ion-selective electrode. The highest fluoride levels were determined in the lowest percentage drinks (less than 10 % v/v ethanol), with the lowest fluoride levels observed in the highest percentage drinks (above 40 % v/v ethanol). In terms of types of alcoholic drinks, the highest fluoride levels were determined in beers and wines, while the lowest levels were observed in vodkas. These data confirm the fact that alcoholic beverages need to be considered as a significant source of fluoride delivered into the body.

  6. Mercury contamination extraction

    Science.gov (United States)

    Fuhrmann, Mark [Silver Spring, MD; Heiser, John [Bayport, NY; Kalb, Paul [Wading River, NY

    2009-09-15

    Mercury is removed from contaminated waste by firstly applying a sulfur reagent to the waste. Mercury in the waste is then permitted to migrate to the reagent and is stabilized in a mercury sulfide compound. The stable compound may then be removed from the waste which itself remains in situ following mercury removal therefrom.

  7. Bioactivity and fluoride release of strontium and fluoride modified Biodentine.

    Science.gov (United States)

    Simila, Hazel O; Karpukhina, Natalia; Hill, Robert G

    2018-01-01

    Biodentine™ is a novel tricalcium silicate based material used both as a coronal dentine replacement and in pulp therapy. Its multiple use in sealing perforations, pulp capping and as a temporary restoration arises from its ability to promote dentine formation and to confer an excellent marginal seal. However, there is still room for improvement of this cement as it lacks the anticariogenic effect typically conferred by fluoride ion release as seen in glass ionomer cement based dental materials. Therefore, this study was conducted to investigate the impact of bioactive glass addition to Biodentine™. was to compare the apatite formation capacity, specificity of the apatite type formed and fluoride ion release by Biodentine™ cements that have been modified by three different compositions of bioactive glasses. High fluoride, high strontium and high fluoride plus strontium containing bioactive glasses were synthesized, incorporated into Biodentine™ powder and four types of cements prepared. These cements were immersed in phosphate buffered saline solution and incubated for a period of 3 and 24h, 3, 7 and 14 days. Fourier transform infra-red spectroscopy, X-ray diffraction, magic angle spinning nuclear magnetic resonance and fluoride ion release studies were performed. Bioactive glass addition to Biodentine™ led to pronounced formation of apatite. Where the bioactive glass contained fluoride, fluorapatite and fluoride ion release were demonstrated. Eliciting fluorapatite formation and fluoride ion release from Biodentine™ is an important development as fluoride is known to have antibacterial and anticariogenic effects. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2011-01-01

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

  9. 49 CFR 173.163 - Hydrogen fluoride.

    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 in...

  10. Growth of fluoride treated Kalanchoe pinnata plants

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, H.N.; Applegate, H.G.

    1962-01-01

    Kalanchoe pinnata plants can absorb fluoride through roots. The absorption is related to the amount of fluoride applied to the soil. There appeared to be a relationship between the amount of fluoride adsorbed and the subsequent growth of the plants. Plants which adsorbed the largest amounts of fluoride had the greatest increase in growth.

  11. Mercury Quick Facts: Health Effects of Mercury Exposure

    Science.gov (United States)

    Mercury Quick Facts Health Effects of Mercury Exposure What is Elemental Mercury? Elemental (metallic) mercury is the shiny, silver-gray metal found in thermometers, barometers, and thermostats and other ...

  12. Curcumin based optical sensing of fluoride in organo-aqueous media using irradiation technique

    Science.gov (United States)

    Venkataraj, Roopa; Radhakrishnan, P.; Kailasnath, M.

    2017-06-01

    The present work describes the degradation of natural dye Curcumin in organic-aqueous media upon irradiation by a multi-wavelength source of light like mercury lamp. The presence of anions in the solution leads to degradation of Curcumin and this degradation is especially enhanced in the case of fluoride ion. The degradation of Curcumin is investigated by studying the change in its absorption and fluorescence characteristics in organoaqueous solution upon irradiation. A broad detection range of fluoride ranging from 2.3×10-6-2.22×10-3 M points to the potential of the method of visible light irradiation enabling aqueous based sensing of fluoride using Curcumin.

  13. Physical properties of thorium fluoride

    International Nuclear Information System (INIS)

    Van Uitert, L.G.; Guggenheim, H.J.; O'Bryan, H.M.; Warner, A.W. Jr.; Brownlow, D.; Bernstein, J.L.; Pasteur, G.A.; Johnson, L.F.

    1976-01-01

    Thorium fluoride has many properties that make it of interest for infrared windows. It is transparent to about eleven microns, is unaffected by moisture, has a moderate hardness, and suffers little dimensional change upon heating

  14. Minamata Convention on Mercury

    Science.gov (United States)

    On November 6, 2013 the United States signed the Minamata Convention on Mercury, a new multilateral environmental agreement that addresses specific human activities which are contributing to widespread mercury pollution

  15. Mercury in Your Environment

    Science.gov (United States)

    Basic information about mercury, how it gets in the air, how people are exposed to it and health effects associated with exposure; what EPA and other organizations are doing to limit exposures; what citizens should know to minimize exposures and to reduce mercury in the environment; and information about products that contain mercury.

  16. Intentional intravenous mercury injection

    African Journals Online (AJOL)

    Three forms of mercury exist: elemental, inorganic and organic, all of which may be toxic with clinical consequences, depending on the type of exposure. Elemental mercury poisoning usually occurs via vapour inhalation, as mercury is well absorbed through the lungs. The central nervous system is then the major site of ...

  17. Chronic Fluoride Toxicity: Dental Fluorosis

    Science.gov (United States)

    DenBesten, Pamela; Li, Wu

    2012-01-01

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

  18. Fluoride bioavailability in saliva and plaque

    Science.gov (United States)

    2012-01-01

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

  19. 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

    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

  20. Urinary fluoride excretion in preschool children after intake of fluoridated milk and use of fluoride-containing toothpaste

    DEFF Research Database (Denmark)

    Norman, M; Twetman, S; Hultgren Talvilahti, A

    2017-01-01

    Objective: To assess the urinary fluoride excretion in preschool children after drinking fluoridated milk with 0.185 mg F and 0.375 mg F and to study the impact of use of fluoride toothpaste. Basic research design: Double-blind cross-over study. Participants: Nine healthy children, 2.5-4.5 years...

  1. Water Fluoridation Reporting System (Public Water Systems)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Water Fluoridation Reporting System (WFRS) has been developed to provide tools to assist states in managing fluoridation programs. WFRS is designed to track all...

  2. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    OpenAIRE

    Dugheri, Stefano; Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Mucci, Nicola; 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 impre...

  3. Effects of fluorides on plants

    Energy Technology Data Exchange (ETDEWEB)

    Yamazoe, F.

    1975-11-01

    Fluorine compounds known to be air pollutants, such as hydrogen fluoride and silicon tetrachloride, are highly poisonous to plants even at ppm - ppb levels. As solid microparticles, acidic sodium fluoride and cryolite cause problems by adhering to plant leaves and absorbing into plant bodies. Plants are classified by their susceptibility to hydrogen fluoride: gladiolus, apricot, buckwheat, turnip and Vaccinium vitis-idaea are most susceptible showing slight injury at less than 5 ppb for 7-9 days; maize, pepper, and dahlia are fairly susceptible, followed by azalea, rose, lilac, and alfalfa, then by oak and tomato. Gladiolus is used as an indicator plant. The exposure factor for one species was known. The symptoms of plants exposed to gaseous fluorine compounds are described in detail at various concentrations. The causal mechanism of the injuries due to fluorine compounds is described in detail, with the method of determining the fluorine content of plant parts. 7 references.

  4. Anhydrous hydrogen fluoride electrolyte battery. [Patent application

    Science.gov (United States)

    Not Available

    1972-06-26

    It is an object of the invention to provide a primary cell or battery using ammonium fluoride--anhydrous hydrogen fluoride electrolyte having improved current and power production capabilities at low temperatures. It is operable at temperatures substantially above the boiling point of hydrogen fluoride. (GRA)

  5. FLUORIDE REMOVAL BY ADSORPTION ON THERMALLY ...

    African Journals Online (AJOL)

    Preferred Customer

    capability. Speciation analysis reveals that at low initial fluoride concentrations the dissolution of gibbsite is facilitated by the adsorption of fluoride onto gibbsite. This may result in the formation of aluminum fluoro complexes in water. KEY WORDS: Fluoride removal, Laterite soils, Speciation analysis, Adsorption capacity, ...

  6. Mercury evaporation from amalgams with varied mercury contents.

    Science.gov (United States)

    Ohmoto, K; Nakajima, H; Ferracane, J L; Shintani, H; Okabe, T

    2000-09-01

    This study examined the relationship between mercury content and mercury evaporation from amalgams during setting. Two different types of commercial high-copper amalgams (single composition and admixed types) were used. Cylindrical specimens of each amalgam were prepared with five different mercury contents according to ADA Specification No.1. Specimens were also prepared by hand condensation. Mercury evaporation from amalgam specimens maintained at 37 degrees C was measured using a gold film mercury analyzer from 10 min after the end of trituration until the mercury concentration in air reached an undetectable level. The mercury content more clearly influenced the mercury evaporation from the admixed type amalgam specimens when the mercury content decreased below the manufacturers' recommended trituration conditions. Triturating with less mercury than the manufacturers' recommended amount cannot lower the evaporation of mercury from freshly made amalgam. Proper condensing procedures can minimize the mercury evaporation from the amalgam surface.

  7. Fluoride Iontophoresis Versus Topical Fluoride Application In The ...

    African Journals Online (AJOL)

    Material and Methods: Test teeth received a 2% neutral solution of sodium fluoride using Desensitron II Iontophoresis device with current and the control teeth received the solution on the device without current. Thirteen patients comprising eight females and five males who complained of tooth hypersensitivity participated in ...

  8. Mercury balance analysis

    International Nuclear Information System (INIS)

    Maag, J.; Lassen, C.; Hansen, E.

    1996-01-01

    A detailed assessment of the consumption of mercury, divided into use areas, was carried out. Disposal and emissions to the environment were also qualified. The assessment is mainly based on data from 1992 - 1993. The most important source of emission of mercury to air is solid waste incineration which is assessed in particular to be due to the supply of mercury in batteries (most likely mercury oxide batteries from photo equipment) and to dental fillings. The second most important source of mercury emission to air is coal-fired power plants which are estimated to account for 200-500 kg of mercury emission p.a. Other mercury emissions are mainly related to waste treatment and disposal. The consumption of mercury is generally decreasing. During the period from 1982/83 - 1992-93, the total consumption of mercury in Denmark was about halved. This development is related to the fact that consumption with regard to several important use areas (batteries, dental fillings, thermometers etc.) has been significantly reduced, while for other purposes the use of mercury has completely, or almost disappeared, i.e. (fungicides for seed, tubes etc.). (EG)

  9. Contribution to the study of the intermediate fluorides of uranium

    International Nuclear Information System (INIS)

    Nguyen-Hoang, Nghi

    1961-10-01

    The reaction of gaseous uranium hexafluoride with solid uranium tetrafluoride has been studied between 20 and 300 deg. C. The intermediate fluorides resulting from this reaction were prepared and then identified by chemical analysis and Debye-Scherrer diagrams. Their magnetic susceptibility and action on various common solvents were determined. The kinetic study was carried out up to 45 deg. C at a constant gas pressure equal to 17,7 mm of mercury. The experimental results indicate that the reaction, limited by the diffusion process of ionic reactants, obeys the kinetic law: L (1 - C) = k√t. The observed rate constant K and the diffusion coefficient D vary with the temperature according to the expressions: K min -1/2 = - (1,88 ± 0,22) 10 8 exp[-(14100 ± 1400 cal/mole)/(RT)]; D cm 2 sec -1 = (1,15 ± 0,51) 10 6 exp[-(30200 ± 5700 cal/mole)/(RT)]. (author) [fr

  10. Process for low mercury coal

    Science.gov (United States)

    Merriam, Norman W.; Grimes, R. William; Tweed, Robert E.

    1995-01-01

    A process for producing low mercury coal during precombustion procedures by releasing mercury through discriminating mild heating that minimizes other burdensome constituents. Said mercury is recovered from the overhead gases by selective removal.

  11. Fluoride and Water (For Parents)

    Science.gov (United States)

    ... a safe and cost-effective way to reduce dental caries. Today, water fluoridation is estimated to reduce tooth ... rinses. But older kids at high risk for tooth decay may benefit from them. ... history of dental disease, recent periodontal surgery or disease, or a ...

  12. 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)

  13. The role of fluoride in erosion therapy.

    Science.gov (United States)

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

    2014-01-01

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

  14. Mercury is Moon's brother

    International Nuclear Information System (INIS)

    Ksanfomalifi, L.V.

    1976-01-01

    The latest information on Mercury planet is presented obtained by studying the planet with the aid of radar and space vehicles. Rotation of Mercury about its axis has been discovered; within 2/3 of its year it executes a complete revolution about its axis. In images obtained by the ''Mariner-10'' Mercurys surface differs little from that of the Moon. The ''Mariner-10'' has also discovered the Mercurys atmosphere, which consists of extremely rarefied helium. The helium is continuously supplied to the planet by the solar wind. The Mercury's magnetic field has been discovered, whose strength is 35 x 10 -4 at the Equator and 70 x 10 -4 E at the poles. The inclination of the dipole axis to the Mercury's rotation axis is 7 deg

  15. Alimentary fluoride intake in preschool children

    Science.gov (United States)

    2011-01-01

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

  16. Peru Mercury Inventory 2006

    Science.gov (United States)

    Brooks, William E.; Sandoval, Esteban; Yepez, Miguel A.; Howard, Howell

    2007-01-01

    In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has long been mined and used in South America for artisanal gold mining and imported for chlor-alkali production, dental amalgam, and other uses. The U.S. Geological Survey (USGS) provides information on domestic and international mercury production, trade, prices, sources, and recycling in its annual Minerals Yearbook mercury chapter. Therefore, in response to UNEP-Chemicals, the USGS, in collaboration with the Economic Section of the U.S. Embassy, Lima, has herein compiled data on Peru's exports, imports, and byproduct production of mercury. Peru was selected for this inventory because it has a 2000-year history of mercury production and use, and continues today as an important source of mercury for the global market, as a byproduct from its gold mines. Peru is a regional distributor of imported mercury and user of mercury for artisanal gold mining and chlor-alkali production. Peruvian customs data showed that 22 metric tons (t) of byproduct mercury was exported to the United States in 2006. Transshipped mercury was exported to Brazil (1 t), Colombia (1 t), and Guyana (1 t). Mercury was imported from the United States (54 t), Spain (19 t), and Kyrgyzstan (8 t) in 2006 and was used for artisanal gold mining, chlor-alkali production, dental amalgam, or transshipment to other countries in the region. Site visits and interviews provided information on the use and disposition of mercury for artisanal gold mining and other uses. Peru also imports mercury-containing batteries, electronics and computers, fluorescent lamps, and thermometers. In 2006, Peru imported approximately 1,900 t of a wide variety of fluorescent lamps; however, the mercury contained in these lamps, a minimum of approximately 76 kilograms (kg), and in

  17. Modeling Mercury in Proteins

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jeremy C [ORNL; Parks, Jerry M [ORNL

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively non-toxic, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. Here we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.

  18. Focus on Fluorides: Update on the Use of Fluoride for the Prevention of Dental Caries

    Science.gov (United States)

    Carey, Clifton M.

    2014-01-01

    Declarative Title: Improving the efficacy of fluoride therapies reduces dental caries and lowers fluoride exposure. Background Fluoride is delivered to the teeth systemically or topically to aid in the prevention of dental caries. Systemic fluoride from ingested sources is in blood serum and can be deposited only in teeth that are forming in children. Topical fluoride is from sources such as community water, processed foods, beverages, toothpastes, mouthrinses, gels, foams, and varnishes. The United States Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) have proposed changes in their long standing recommendations for the amount of fluoride in community drinking water in response to concerns about an increasing incidence of dental fluorosis in children. Current research is focused on the development of strategies to improve fluoride efficacy. The purpose of this update is to inform the reader about new research and policies related to the use of fluoride for the prevention of dental caries. Methods Reviews of the current research and recent evidence based systematic reviews on the topics of fluoride are presented. Topics discussed include: updates on community water fluoridation research and policies; available fluoride in dentifrices; fluoride varnish compositions, use, and recommendations; and other fluoride containing dental products. This update provides insights into current research and discusses proposed policy changes for the use of fluoride for the prevention of dental caries. Conclusions The dental profession is adjusting their recommendations for fluoride use based on current observations of the halo effect and subsequent outcomes. The research community is focused on improving the efficacy of fluoride therapies thus reducing dental caries and lowering the amount of fluoride required for efficacy. PMID:24929594

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

    Science.gov (United States)

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

    2009-01-01

    This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to Duraphat. The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM). After 1-month interval (phase II), the same amount (0.2 mL) of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, Colgate) was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (papplication of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.

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

    Science.gov (United States)

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

    2013-01-01

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

  1. Intentional intravenous mercury injection

    African Journals Online (AJOL)

    In this case report, intravenous complications, treatment strategies and possible ... Mercury toxicity is commonly associated with vapour inhalation or oral ingestion, for which there exist definite treatment options. Intravenous mercury ... personality, anxiousness, irritability, insomnia, depression and drowsi- ness.[1] However ...

  2. International mercury conference

    CSIR Research Space (South Africa)

    Leaner, J

    2006-10-01

    Full Text Available Mercury (Hg) affects human health and the environment, it calls for immediate action. Action is needed at local, regional and international level to reduce the risk associated with mercury, which is a global international problem, as it is a...

  3. Mercury's shifting, rolling past

    OpenAIRE

    Trulove, Susan

    2008-01-01

    Patterns of scalloped-edged cliffs or lobate scarps on Mercury's surface are thrust faults that are consistent with the planet shrinking and cooling with time. However, compression occurred in the planet's early history and Mariner 10 images revealed decades ago that lobate scarps are among the youngest features on Mercury. Why don't we find more evidence of older compressive features?

  4. MESSENGER: Exploring Mercury's Magnetosphere

    Science.gov (United States)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  5. Global Mercury Assessment 2013

    International Development Research Centre (IDRC) Digital Library (Canada)

    mercury pollution. This summary report and the accompanying. Technical Background Report for the Global. Mercury Assessment 2013 are developed in response to Decision 25/5, paragraph ... The use of different pollution control technologies in different ...... vegetation, snow, freshwater, and seawater. One of the largest ...

  6. Groundwater fluoride contamination: A reappraisal

    Directory of Open Access Journals (Sweden)

    Amlan Banerjee

    2015-03-01

    Full Text Available Dissolution of fluorite (CaF2 and/or fluorapatite (FAP [Ca5(PO43F], pulled by calcite precipitation, is thought to be the dominant mechanism responsible for groundwater fluoride (F− contamination. Here, one dimensional reactive–transport models are developed to test this mechanism using the published dissolution and precipitation rate kinetics for the mineral pair FAP and calcite. Simulation results correctly show positive correlation between the aqueous concentrations of F− and CO32− and negative correlation between F− and Ca2+. Results also show that precipitation of calcite, contrary to the present understanding, slows down the FAP dissolution by 106 orders of magnitude compared to the FAP dissolution by hydrolysis. For appreciable amount of fluoride contamination rock–water interaction time must be long and of order 106 years.

  7. Computer simulation of superionic fluorides

    CERN Document Server

    Castiglione, M

    2000-01-01

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

  8. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    Science.gov (United States)

    Fries, B.A.

    1959-11-10

    A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

  9. Thermodynamic data for uranium fluorides

    International Nuclear Information System (INIS)

    Leitnaker, J.M.

    1983-03-01

    Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF 4 and UF 6 , including UF 4 (solid and gas), U 4 F 17 (solid), U 2 F 9 (solid), UF 5 (solid and gas), U 2 F 10 (gas), and UF 6 (solid, liquid, and gas). Included are thermal function - the heat capacity, enthalpy, and free energy function, heats of formation, and vaporization behavior

  10. Compton profile of calcium fluoride

    International Nuclear Information System (INIS)

    Vijayakumar, R.; Rajasekaran, L.; Ramamurthy, N.; Shivaramu

    2003-01-01

    Full text: The Compton profile of polycrystalline calcium fluoride is measured using 661.6 keV γ- radiation from a 137 Cs source. The experimental data are compared with HF-LCAO model calculation computed using CRYSTAL98 program, Hartree-Fock free atom theoretical values and with the other available experimental data. Experimental results are found to be in good agreement with the HF-LCAO model calculations and in qualitative agreement with Hartree-Fock free atom theoretical values

  11. Fluoride Supplementation Adherence and Barriers in a Community Without Water Fluoridation.

    Science.gov (United States)

    Flood, Shannon; Asplund, Karin; Hoffman, Benjamin; Nye, Allison; Zuckerman, Katharine E

    2017-04-01

    To prevent early childhood caries, the American Dental Association recommends oral fluoride supplementation for children in communities lacking water fluoridation who are at high caries risk. However, patient adherence to oral fluoride supplementation has not been studied in this population. This study assessed adherence to oral fluoride and barriers to adherence in a community lacking water fluoridation. A self-administered survey was completed in a systematic sample of 209 parents of children aged 6 months to 4 years, during a primary care visit in an urban academic medical center. Participants reported frequency of administering oral fluoride to their children, as well as agreement or disagreement with proposed barriers to supplementation. Bivariate and multivariate analyses were used to assess adherence with oral supplementation and the association of barriers to supplementation and child receipt of fluoride on the day before. More than half of parents either had not or did not know if their child had received fluoride on the day before. Approximately 1 in 4 of parents had given fluoride in 0 of the previous 7 days. Difficulty remembering to give fluoride and agreeing that the child does not need extra fluoride were associated with not receiving fluoride on the day before. Adherence to oral fluoride supplementation in the primary care setting is low. Difficulty remembering to give fluoride daily is the greatest barrier to adherence. Further research on interventions to reduce common barriers is needed to increase fluoride administration and reduce early childhood caries in communities lacking water fluoridation. Copyright © 2016 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

  12. Municipal actions to reduce mercury

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-03-15

    This paper presented proper management practices for products containing mercury. The measures can help reduce mercury releases, occupational exposure and mercury spills, thereby preventing impacts on human health and the environment. Despite mercury's toxic nature, many common products that contain mercury are commercially available. These include thermostats, thermometers, fluorescent lamps, pressure measuring devices, electrical switches and relays, and dental amalgam. Mercury emissions are also associated with base metal smelting, waste incineration and coal-fired power generation. Mercury in the environment is a global issue, because it can travel in the atmosphere on wind currents. The actions taken by municipalities to address the issue include reducing or eliminating mercury releases from internal municipal operations and sources within the community. This document provided guidance on how to develop a Municipal Mercury Elimination Policy and Plan that will help reduce mercury releases. It presented information and case studies that will help municipalities manage mercury-containing products found in municipal buildings and street lighting. Information on sources of mercury from within the community was presented along with case studies that can help municipalities determine where community action is needed to reduce mercury releases. The 5 modules of this document were intended to help municipalities identify priorities, timelines and budget requirements for mercury initiatives. It was emphasized that municipalities that adopt a Municipal Mercury Elimination Policy and Plan formally commit to reducing and eliminating mercury from the environment. tabs., figs.

  13. Getting Mercury out of Schools.

    Science.gov (United States)

    1999

    This guide was prepared while working with many Massachusetts schools to remove items that contain mercury and to find suitable alternatives. It contains fact sheets on: mercury in science laboratories and classrooms, mercury in school buildings and maintenance areas, mercury in the medical office and in medical technology classrooms in vocational…

  14. Assessing fluoride levels of carbonated soft drinks.

    Science.gov (United States)

    Heilman, J R; Kiritsy, M C; Levy, S M; Wefel, J S

    1999-11-01

    Dental fluorosis occurs as a result of excessive total fluoride intake during tooth development. Some children may receive substantial intake from soft drinks, but few studies have reported fluoride levels in soft drinks. The authors examined the fluoride concentrations of 332 soft drinks. Soft drinks were purchased from Iowa grocery stores. To identify production sites, the authors recorded product details and batch numbers. After decarbonating the drinks, the authors assayed samples for fluoride content using a fluoride ion-specific electrode, and reported the results in parts per million, or ppm, using appropriate standards and duplicate assessments. Descriptive statistics were used to summarize the findings. The fluoride levels of the products ranged from 0.02 to 1.28 ppm, with a mean level of 0.72 ppm. Fluoride levels exceeded 0.60 ppm for 71 percent of the products. Results varied substantially by production site, even within the same company and for the same product. There were no substantial differences between flavors or between diet and regular soft drinks. The majority of soft drinks had fluoride levels exceeding 0.60 ppm. Variation in fluoride levels probably is due largely to the different water sources used in production. With no fluoride levels marked on the soft drink products or easily available from the manufacturers, it is not possible for clinicians or consumers to directly estimate fluoride ingestion from carbonated beverages. Therefore, to reduce the risk of dental fluorosis, dental and medical practitioners should be cautious about prescribing dietary fluoride supplements to preschool-aged children in nonfluoridated areas who consume large quantities of carbonated soft drinks.

  15. Estuarine response of fluoride - Investigations in Azhikode Estuary

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  16. Study of fluoride in polluted and unpolluted estuarine environments

    Digital Repository Service at National Institute of Oceanography (India)

    Zingde, M.D.; Mandalia, A.V.

    Mindhola river estuary, which receives industrial waste containing high concentrations of fluoride, and Purna River estuary, which is free from fluoride contamination, have been investigated. While fluoride behaved conservatively in Purna River...

  17. Mercury's Dynamic Magnetic Tail

    Science.gov (United States)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

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

    Directory of Open Access Journals (Sweden)

    Kelly Polido Kaneshiro Olympio

    2009-06-01

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

  19. Inorganic: the other mercury.

    Science.gov (United States)

    Risher, John F; De Rosa, Christopher T

    2007-11-01

    There is a broad array of mercury species to which humans may be exposed. While exposure to methylmercury through fish consumption is widely recognized, the public is less aware of the sources and potential toxicity of inorganic forms of mercury. Some oral and laboratory thermometers, barometers, small batteries, thermostats, gas pressure regulators, light switches, dental amalgam fillings, cosmetic products, medications, cultural/religious practices, and gold mining all represent potential sources of exposure to inorganic forms of mercury. The route of exposure, the extent of absorption, the pharmacokinetics, and the effects all vary with the specific form of mercury and the magnitude and duration of exposure. If exposure is suspected, a number of tissue analyses can be conducted to confirm exposure or to determine whether an exposure might reasonably be expected to be biologically significant. By contrast with determination of exposure to methylmercury, for which hair and blood are credible indicators, urine is the preferred biological medium for the determination of exposure to inorganic mercury, including elemental mercury, with blood normally being of value only if exposure is ongoing. Although treatments are available to help rid the body of mercury in cases of extreme exposure, prevention of exposure will make such treatments unnecessary. Knowing the sources of mercury and avoiding unnecessary exposure are the prudent ways of preventing mercury intoxication. When exposure occurs, it should be kept in mind that not all unwanted exposures will result in adverse health consequences. In all cases, elimination of the source of exposure should be the first priority of public health officials.

  20. Recovery of mercury from mercury compounds via electrolytic methods

    Science.gov (United States)

    Grossman, Mark W.; George, William A.

    1988-01-01

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg.sub.2 Cl.sub.2 employing as the electrolyte solution a mixture of HCl and H.sub.2 O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H.sub.2 O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds.

  1. CORRELATION AMONG FLUORIDE AND METALS IN IRRIGATION ...

    African Journals Online (AJOL)

    Preferred Customer

    include the following: the industrial production and use of chemicals and phosphate fertilizers. Phosphate ... and distribution pattern fluoride in Ethiopian Rift Valley water [7, 8], fluoride binding capacity of different types .... sample was transferred in to labeled, pre-cleaned plastic bottles after rinsing with the water sample and ...

  2. Biomonitoring Equivalents for interpretation of urinary fluoride.

    Science.gov (United States)

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

    2015-06-01

    Exposure to fluoride is widespread due to its natural occurrence in the environment and addition to drinking water and dental products for the prevention of dental caries. The potential health risks of excess fluoride exposure include aesthetically unacceptable dental fluorosis (tooth mottling) and increased skeletal fragility. Numerous organizations have conducted risk assessments and set guidance values to represent maximum recommended exposure levels as well as recommended adequate intake levels based on potential public health benefits of fluoride exposure. Biomonitoring Equivalents (BEs) are estimates of the average biomarker concentrations corresponding to such exposure guidance values. The literature on daily urinary fluoride excretion rates as a function of daily fluoride exposure was reviewed and BE values corresponding to the available US and Canadian exposure guidance values were derived for fluoride in urine. The derived BE values range from 1.1 to 2.1mg/L (1.2-2.5μg/g creatinine). Concentrations of fluoride in single urinary spot samples from individuals, even under exposure conditions consistent with the exposure guidance values, may vary from the predicted average concentrations by several-fold due to within- and across-individual variation in urinary flow and creatinine excretion rates and due to the rapid elimination kinetics of fluoride. Thus, the BE values are most appropriately applied to screen population central tendency estimates for biomarker concentrations rather than interpretation of individual spot sample concentrations. Copyright © 2015. Published by Elsevier Inc.

  3. Potentiometric Determination of Fluoride Concentration in Beers.

    Science.gov (United States)

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

    2018-01-01

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

  4. Hydrogeochemical framework and factor analysis of fluoride ...

    African Journals Online (AJOL)

    Fluoride contamination of groundwater within the Savelugu-Nanton District was assessed using hydrogeochemical framework and multivariate statistical approach. Eighty-one (No) boreholes were sampled for quality assessment in May and June 2008. The main objective of this study was to assess the fluoride levels in ...

  5. Fluoride ions vs removal technologies: A study

    Directory of Open Access Journals (Sweden)

    Jagvir Singh

    2016-11-01

    Full Text Available Literature reported that drinking water is a precious and scarce resource and it has to be protected and kept free from any kind of contamination. Further, it has to be used carefully without wasting. Literature also reported that fluoride bearing rocks are abundant in India, as a result, fluoride leaches out and contaminates the adjacent water and soil resources. A high concentration of fluoride ions in ground water increases up to more than 30 mg/L. This high concentration of fluoride ions causes many harmful and dangerous effects on our datum. Fluoride ions in larger quantities i.e. 20–80 mg/day taken over a period of 10–20 years result in crippling and skeletal fluorosis, severely damaging the bone. In the present scenario, there is a continuously increasing worldwide concern for the development of fluoride treatment technologies. Possibilities of reducing the high fluorine content in groundwater are by defluorination process/dilution with the surface water which is a very simple technique but the addition of Ca2+ ions to a solution in contact with fluorite when experimented in distilled water caused an appreciable decrease in fluoride concentration. In this review article, we emphasized the relationship between high concentrations of fluoride ions and their compounds and their health impact.

  6. Cycling of fluoride in a mangrove community near a fluoride emission source. [Avicennia marina (Forski)

    Energy Technology Data Exchange (ETDEWEB)

    Murray, F.

    1985-04-01

    A comparison of stands of immature grey mangroves, Avicennia marina (Forsk.) Vierh., growing near a fluoride emission source (Kooragang Island, Australia) and a relatively unpolluted area (Gosford) showed that A. marina can accumulate high concentrations of fluoride particularly in leaves, generally without visible injury. Fluoride input to the Kooragang Island ecosystem as bulk deposition of gaseous and particulate fluoride was found to be 0.31 g m/sup -2/ yr/sup -1/ and this varied with the distance and direction of each site in relation to fluoride emission sources. The above-ground biomass at both sites was practically identical but the fluoride concentration of leaves and branches were almost two orders of magnitude greater at Kooragang Island than at Gosford. A comparison of plant litterfall, fluoride concentration and fluoride deposition in litterfall at the Kooragang Island site and at Fullerton Cove showed that although litterfall rates were similar the rates of fluoride deposition in litterfall were also two orders of magnitude different due to the differences in fluoride concentration in all components of plant litter at the two sites. These litterfall rates are similar to other data reported for mangrove litter production at the same latitude. As a consequence of fluoride input by litterfall, wet deposition and dry deposition buffer-extractable fluoride concentrations in soils at Kooragang Island were generally within the range 4-15 ..mu..gF g/sup -1/. At Fullerton Cove and Gosford the buffer-extractable fluoride concentrations in soil were relatively constant with mean fluoride concentrations of 2.0 and 1.9 ..mu..gF g/sup -1/ respectively. Mangrove communities may export up to 25 kg ha /sup 1/ day /sup 1/ of detritus to estuarine food webs of commercial and ecological importance.

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

    Science.gov (United States)

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

    2014-01-01

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

  8. The tectonics of Mercury

    International Nuclear Information System (INIS)

    Melosh, H.J.; Mckinnon, W.B.

    1988-01-01

    The probable tectonic history of Mercury and the relative sequence of events are discussed on the basis of data collected by the Mariner-10 spacecraft. Results indicate that Mercury's tectonic activity was confined to its early history; its endogenic activity was principally due to a small change in the shape of its lithosphere, caused by tidal despinning, and a small change in area caused by shrinkage due to cooling. Exogenic processes, in particular the impact activity, have produced more abundant tectonic features. Many features associated with the Caloris basin are due to loading of Mercury's thick lithosphere by extrusive lavas or subsidence due to magma withdrawal. It is emphasized that tectonic features observed on Mercury yield insight into the earliest tectonic events on planets like Mars and, perhaps, the earth, where subsequent events obscured or erased the most ancient tectonic records

  9. Thermodynamic data for uranium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Leitnaker, J.M.

    1983-03-01

    Self-consistent thermodynamic data have been tabulated for uranium fluorides between UF/sub 4/ and UF/sub 6/, including UF/sub 4/ (solid and gas), U/sub 4/F/sub 17/ (solid), U/sub 2/F/sub 9/ (solid), UF/sub 5/ (solid and gas), U/sub 2/F/sub 10/ (gas), and UF/sub 6/ (solid, liquid, and gas). Included are thermal function - the heat capacity, enthalpy, and free energy function, heats of formation, and vaporization behavior.

  10. Niobium electrodeposition from molten fluorides

    International Nuclear Information System (INIS)

    Sartori, A.F.

    1987-01-01

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

  11. Measurement of fluoride in bone

    International Nuclear Information System (INIS)

    Mernagh, J.R.; Harrision, J.E.; Hancock, R.; McNeill, K.G.

    1977-01-01

    The fluorine concentration in bone biopsy samples was measured by neutron activation analysis. The fluorine content was expressed in terms of the calcium content. Samples were irradiated in a reactor to induce the 19 F(n,γ) 20 F and 48 Ca(n,γ) 49 Ca reactions and after rapid transport from the reactor the resulting activities were measured with a Ge(Li) detector. Reproducibility was better than 10% for the F/Ca ratio. The detection limit for F is 50 μg. This nondestructive technique will be used to assess the effect of fluoride therapy on bone metabolism of patients with idiopathic osteoporosis. (author)

  12. Mercury CEM Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John F. Schabron; Joseph F. Rovani; Susan S. Sorini

    2007-03-31

    The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapor pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.

  13. Mercury in human hair

    International Nuclear Information System (INIS)

    Kapauan, P.A.; Cruz, C.C.; Verceluz, F.P.

    1980-10-01

    The analysis of mercury (Hg) in scalp hair obtained from individuals residing in five different localities in the Philippines - Metro Manila, Naga City in Bicol, Bataan, Oriental Mindoro, and Palawan is presented. An overall mean of 1.46 ug/g of hair was obtained for all samples excluding those from Palawan and represents a baseline value.'' In terms of the mercury levels found in hair, the Honda Bay area in Palawan is, relatively, a ''contaminated area.'' (author)

  14. Determination of Fluoride in Different Toothpaste Formulations

    International Nuclear Information System (INIS)

    Kamau, N.G.; Njoroge, M.; Njau, M.

    1998-01-01

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

  15. Fluoride Importance in Controlling Caries and Fluorosis

    Directory of Open Access Journals (Sweden)

    Gaurav Solanki

    2012-04-01

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

  16. Method and apparatus for monitoring mercury emissions

    Science.gov (United States)

    Durham, Michael D.; Schlager, Richard J.; Sappey, Andrew D.; Sagan, Francis J.; Marmaro, Roger W.; Wilson, Kevin G.

    1997-01-01

    A mercury monitoring device that continuously monitors the total mercury concentration in a gas. The device uses the same chamber for converting speciated mercury into elemental mercury and for measurement of the mercury in the chamber by radiation absorption techniques. The interior of the chamber is resistant to the absorption of speciated and elemental mercury at the operating temperature of the chamber.

  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 (p<0.001). Necropsy examinations of all six species from the high-fluoride area near the smelter revealed dental lesions considered characteristic of dental fluorosis in eutherian mammals. Within the high-fluoride area, 67% of individuals across the six species showed dental enamel lesions, compared to 3% in the low-fluoride areas. Molars that erupted before weaning were significantly less likely to display pathological lesions than those developing later, and molars in the posterior portion of the dental arcade were more severely fluorotic than anterior molars in all six species. The severity of dental lesions was positively associated with increasing bone fluoride levels in all species, revealing a potential biomarker of excess fluoride exposure. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Mercury pollution in Malaysia.

    Science.gov (United States)

    Hajeb, Parvaneh; Jinap, S; Ismail, Ahmad; Mahyudin, Nor Ainy

    2012-01-01

    Although several studies have been published on levels of mercury contamination of the environment, and of food and human tissues in Peninsular Malaysia, there is a serious dearth of research that has been performed in East Malaysia (Sabah and Sarawak). Industry is rapidly developing in East Malaysia, and, hence, there is a need for establishing baseline levels of mercury contamination in environmental media in that part of the country by performing monitoring studies. Residues of total mercury and inorganic in food samples have been determined in nearly all previous studies that have been conducted; however, few researchers have analyzed samples for the presence of methlymercury residues. Because methylmercury is the most toxic form of mercury, and because there is a growing public awareness of the risk posed by methylmercury exposure that is associated with fish and seafood consumption, further monitoring studies on methylmercury in food are also essential. From the results of previous studies, it is obvious that the economic development in Malaysia, in recent years, has affected the aquatic environment of the country. Primary areas of environmental concern are centered on the rivers of the west Peninsular Malaysian coast, and the coastal waters of the Straits of Malacca, wherein industrial activities are rapidly expanding. The sources of existing mercury input to both of these areas of Malaysia should be studied and identified. Considering the high levels of mercury that now exists in human tissues, efforts should be continued, and accelerated in the future, if possible, to monitor mercury contamination levels in the coastal states, and particularly along the west Peninsular Malaysian coast. Most studies that have been carried out on mercury residues in environmental samples are dated, having been conducted 20-30 years ago; therefore, the need to collect much more and more current data is urgent. Furthermore, establishing baseline levels of mercury exposure to

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

    Science.gov (United States)

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

    2017-09-01

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

  20. Fabrication of mercury target vessel

    International Nuclear Information System (INIS)

    Wakui, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Futakawa, Masatoshi; Hayashi, Ryoichi; Uchiyama, Naoyoshi; Okamoto, Yoshinao; Nakamura, Koji

    2010-03-01

    The construction of materials and life science experimental facility in J-PARC (Japan Proton Accelerator Complex) project had been completed and accepted pulsed proton beams with low power. Since 2003, the detailed design, fabrication and examination for the mercury target vessel as a pulsed neutron source were carried out by the vender. The mercury target vessel consists of triple-walled structure in order to prevent the leak of mercury to outside at the failure of the mercury vessel and to remove the heat of the safety hull, which covers the mercury vessel, due to the injection of the pulsed proton beams. The high fabrication accuracy is required for the mercury target vessel assembled by the welding, because there are the relationships between the mercury target vessel and other components (target trolley, target storage container, flange of helium vessel, reflector and water-cooled shield). At each fabrication step, the examinations for the mercury target vessel with multi-walled structure were required. In this report, the required specification and basic structure of parts in the mercury target vessel are described and the fabrication procedure of the mercury target vessel by the vender is reported. In the fabrication of the mercury target vessel, there were many troubles such as large deformation due to the welding and then the vender repaired and brought the mercury target vessel to completion. Furthermore, improvements for the design and fabrication of the mercury target are reported. (author)

  1. Fluoride removal by adsorption on thermally treated lateritic soils ...

    African Journals Online (AJOL)

    The ability of lateritic soils to remove fluoride from water has been studied. Important issues considered in the study include the relation between the mineral composition of soils and their ability to remove fluoride, the effect of thermal treatment of the soil on fluoride removal; the predominant fluoride containing species ...

  2. Studies on the comparative effect of sodium fluoride on collagen ...

    African Journals Online (AJOL)

    Fluoride is an essential element for the normal development and growth of human beings. The main source of fluoride for humans is the intake of groundwater. At high levels, fluoride causes dental and skeletal fluorosis. In this study, control and sodium fluoride (NaF) treated groups of rats had significant (p < 0.05) higher ...

  3. Mercury Emissions: The Global Context

    Science.gov (United States)

    Mercury emissions are a global problem that knows no national or continental boundaries. Mercury that is emitted to the air can travel thousands of miles in the atmosphere before it is eventually deposited back to the earth.

  4. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Science.gov (United States)

    Sauerheber, Richard

    2013-01-01

    The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings. PMID:23840230

  5. Fluoride

    Science.gov (United States)

    Advance White® ... Simply White® ... In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has ...

  6. Mercury's magnetic field and interior

    International Nuclear Information System (INIS)

    Connerney, J.E.P.; Ness, N.F.

    1988-01-01

    The magnetic-field data collected on Mercury by the Mariner-10 spacecraft present substantial evidence for an intrinsic global magnetic field. However, studies of Mercury's thermal evolution show that it is most likely that the inner core region of Mercury solidified or froze early in the planet's history. Thus, the explanation of Mercury's magnetic field in the framework of the traditional planetary dynamo is less than certain

  7. Recognition and sensing of fluoride anion.

    Science.gov (United States)

    Cametti, Massimo; Rissanen, Kari

    2009-05-28

    Fluoride anion recognition is attracting a mounting interest in the scientific community due to its duplicitous nature. It is a useful chemical for many industrial applications, and it has been used in human diet, but, recently it has been accused for several human pathologies. Here we describe the ample panorama of different approaches the chemists world-wide have employed to face the challenge of fluoride binding, and we outline some of the research which in our view can contribute to the development of this field, especially when fluoride binding has to be achieved in highly competitive protic solvents and water.

  8. Reference Atmosphere for Mercury

    Science.gov (United States)

    Killen, Rosemary M.

    2002-01-01

    We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

  9. Mercury content of edible mushrooms

    Energy Technology Data Exchange (ETDEWEB)

    Woidich, H.; Pfannhauser, W.

    1975-05-01

    The mercury content of edible fungi is different. Relatively high burdened are Boletus and Agaricus campestris. A minimum of mercury is found in Russula, Agaricus bisporus and Cantharellus cibarius. The possibilities of mercury uptake and the potential cumulation mechanism is discussed. 8 references, 3 tables.

  10. Mercury (Environmental Health Student Portal)

    Science.gov (United States)

    ... Water Waterborne Diseases & Illnesses Water Cycle Water Treatment Mercury The Basics Mercury — sometimes called quicksilver — is a natural metal. It’s ... to breathe it in without knowing it. When mercury combines with other chemical elements, it creates compounds, ...

  11. Fluoride exposure and reported learning disability diagnosis among Canadian children: Implications for community water fluoridation.

    Science.gov (United States)

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

    2017-09-14

    Recent studies have connected increased fluoride exposure with increased risk of neurodevelopmental-related outcomes, such as ADHD (attention deficit hyperactivity disorder) and lower IQ in children. Our primary objective was to examine the association between fluoride exposure and reported diagnosis of a learning disability among a population-based sample of Canadian children aged 3-12 years. We analyzed data from Cycles 2 and 3 of the Canadian Health Measures Survey. Four measures of fluoride exposure were available: 1) urinary fluoride (μmol/L), 2) creatinine-adjusted urinary fluoride (μmol/mmol), 3) specific gravity-adjusted urinary fluoride (μmol/L), and 4) fluoride concentration of tap water (mg/L) (Cycle 3 only). Diagnosis of a learning disability (yes/no) was based on parental- or self-report. Associations were examined using logistic regression (where possible), unadjusted and adjusted for covariates. When Cycles 2 and 3 were examined separately, reported learning disability diagnosis was not significantly associated with any measure of fluoride exposure in unadjusted or adjusted models. When Cycles 2 and 3 were combined, a small but statistically significant effect was observed such that children with higher urinary fluoride had higher odds of having a reported learning disability in the adjusted model (p = 0.03). However, the association was not observed in models that used creatinine-adjusted urinary fluoride and specific gravity-adjusted urinary fluoride, which are believed to be more accurate measures due to their correction for urinary dilution. Overall, there did not appear to be a robust association between fluoride exposure and parental- or self-reported diagnosis of a learning disability among Canadian children.

  12. Sensing Mercury for Biomedical and Environmental Monitoring

    Directory of Open Access Journals (Sweden)

    Julia Xiaojun Zhao

    2009-07-01

    Full Text Available Mercury is a very toxic element that is widely spread in the atmosphere, lithosphere, and surface water. Concentrated mercury poses serious problems to human health, as bioaccumulation of mercury within the brain and kidneys ultimately leads to neurological diseases. To control mercury pollution and reduce mercury damage to human health, sensitive determination of mercury is important. This article summarizes some current sensors for the determination of both abiotic and biotic mercury. A wide array of sensors for monitoring mercury is described, including biosensors and chemical sensors, while piezoelectric and microcantilever sensors are also described. Additionally, newly developed nanomaterials offer great potential for fabricating novel mercury sensors. Some of the functional fluorescent nanosensors for the determination of mercury are covered. Afterwards, the in vivo determination of mercury and the characterization of different forms of mercury are discussed. Finally, the future direction for mercury detection is outlined, suggesting that nanomaterials may provide revolutionary tools in biomedical and environmental monitoring of mercury.

  13. Chlorophytum susceptibility to fluoride injury

    Energy Technology Data Exchange (ETDEWEB)

    Matkin, O.A.

    1977-01-01

    Experiments were performed to investigate the cause of leaf tip burn in Chlorophytum using varying concentrations of F. Only one case of superimposed fluoride exposure was evaluated. All other mediums were considered safely low in F. Analyses of foliage at the conclusion of the trials showed relatively low and safe concentrations of F in all treatments. The most important observation was that none of the treatments produced any measurable degree of leaf tip burn. The surprising result was that irrigation water fortified with F failed to produce any adverse reaction. It was concluded that much of the injury to Chlorophytum previously attributed to F was probably due to unfavorable cultural conditions, rather than F.

  14. REDUCTION OF FLUORIDE TO METAL

    Science.gov (United States)

    Carlson, O.N.; Schmidt, F.A.; Spedding, F.H.

    1960-08-30

    A process is given for making yttrium metal by reducing yttrium fluoride with calcium plus magnesium. Calcium is added in an excess of from 10 to 20% and magnesium in a quantity to yield a magnesium--yttrium alloy containing from 12 to 25% magnesium when the reaction mass is heated in an inert atmosphere at from 900 to 1106 deg C, but preferably above the melting point of the alloy. Calcium chloride may be added so as to obtain a less viscous slag containing from 30 to 60% calcium chloride. After removal of the slag the alloy is vacuum-heated at about 1100 deg C for volatilization of the magnesium and calcium.

  15. Fluoride release, recharge and mechanical property stability of various fluoride-containing resin composites.

    Science.gov (United States)

    Naoum, S; Ellakwa, A; Martin, F; Swain, M

    2011-01-01

    To determine the fluoride release and recharge of three fluoride-containing resin composites when aged in deionized water (pH 6.5) and lactic acid (pH 4.0) and to assess mechanical properties of these composites following aging. Three fluoride-containing resin composites were analyzed in this study; a new giomer material named Beautifil II, Gradia Direct X, and Tetric EvoCeram. A glass ionomer cement, Fuji IX Extra, was also analyzed for comparison. Specimens were fabricated for two test groups: group 1 included 10 disc specimens initially aged 43 days in deionized water (five specimens) and lactic acid (five specimens). The fluoride release from these specimens was measured using a fluoride-specific electrode on nine specific test days during the aging period. Following 49 days of aging, each specimen was recharged in 5000 ppm neutral sodium fluoride solution for 5 minutes. Specimen recharge was then repeated on a weekly basis for 3 weeks. The subsequent fluoride rerelease was measured at 1, 3, and 7 days after each recharge episode. Group 2 included six disc specimens aged for 3 months in deionized water (three specimens) and lactic acid (three specimens). The hardness and elastic modulus of each specimen was measured using nano-indentation at intervals of 24 hours, 1 month, and 3 months after fabrication. Two-way factorial analysis of variance (ANOVA) and post-hoc (Tukey) testing was used to assess the influence of storage media (two levels) and composite type (three levels) on the fluoride release, fluoride rerelease, hardness, and elastic modulus of the assessed materials. The level of significance was set at p=0.05. All three composites demonstrated fluoride release and recharge when aged in both deionized water and lactic acid. The cumulative fluoride released from Beautifil II into both media was substantially greater than the fluoride released from Gradia Direct X and Tetric EvoCeram after 43 days aging and was significantly (ptest) greater during several

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

    Science.gov (United States)

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

    2008-06-01

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

  17. Water displacement mercury pump

    Science.gov (United States)

    Nielsen, M.G.

    1984-04-20

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  18. Removal of fluoride from aqueous nitric acid

    International Nuclear Information System (INIS)

    Pruett, D.J.; Howerton, W.B.; Mailen, J.C.

    1981-06-01

    Several methods for removing fluoride from aqueous nitric acid were investigated and compared with the frequently used aluminum nitrate-calcium nitrate (Ca 2+ -Al 3+ ) chemical trap-distillation system. Zirconium oxynitrate solutions were found to be superior in preventing volatilization of fluoride during distillation of the nitric acid, producing decontamination factors (DFs) on the order of 2 x 10 3 (vs approx. 500 for the Ca 2+ -Al 3+ system). Several other metal nitrate systems were tested, but they were less effective. Alumina and zirconia columns proved highly effective in removing HF from HF-HNO 3 vapors distilled through the columns; fluoride DFs on the order of 10 6 and 10 4 , respectively, were obtained. A silica gel column was very effective in adsorbing HF from HF-HNO 3 solutions, producing a fluoride DF of approx. 10 4

  19. Mercury CEM Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John Schabron; Joseph Rovani; Mark Sanderson

    2008-02-29

    Mercury continuous emissions monitoring systems (CEMS) are being implemented in over 800 coal-fired power plant stacks. The power industry desires to conduct at least a full year of monitoring before the formal monitoring and reporting requirement begins on January 1, 2009. It is important for the industry to have available reliable, turnkey equipment from CEM vendors. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The generators are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 requires that calibration be performed with NIST-traceable standards (Federal Register 2007). Traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued an interim traceability protocol for elemental mercury generators (EPA 2007). The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The document is divided into two separate sections. The first deals with the qualification of generators by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the generator models that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma/mass spectrometry performed by NIST in Gaithersburg, MD. The

  20. Fluoride method for silicon determination i silicovadium

    International Nuclear Information System (INIS)

    Komarnitskaya, N.N.; Sergeev, K.I.; Shamraj, Z.Ya.

    1977-01-01

    The method used was based on formation of a silicon-potassium fluoride-sodium sediment in strongly acid medium in the presence of excess potassium chloride which decreased the sediment solubility. The sediment was dissolved in hot water to titrate the resultant hydrofluoric acid with a caustic potash solution in the presence of phenolphthalein. Gravity hydrochloric and volumetric fluoride methods were used to compare the results of silicon estimation

  1. FLUORIDE LEVELS IN COMMERCIALLY AVAILABLE RICE IN ...

    African Journals Online (AJOL)

    Preferred Customer

    2013-05-05

    May 5, 2013 ... E-mail: bscv2006@yahoo.com. FLUORIDE LEVELS IN .... Varying levels of several metals such as Na, K, Ca, Mg, Fe, Mn, Zn, Ni, Co, Cd, and Pb [21, 28-. 33] in different types of rice .... was 0.2 mg/L, and in tap water added fluoride to the levels of 3, 6 and 10 mg F/L. Difference in amount of water used and ...

  2. Recovery of fluoride ion selective electrode

    International Nuclear Information System (INIS)

    Monteiro, R.P.G.

    1988-01-01

    A recovery procedure of fluoride ion selective electrode based upon the body radiography of inactive electrode and introduction of suitable internal regeneration solution, is developed. The recovered electrode was tested in standard solutions of fluoride ions (10 sup5) to 10 -1M showing as good performance as the new one. The fluor determination by potentiometric measurements with selective electrode is used in nuclear fuel cycle for quality control of thorium and uranium mixed oxide pellets and pellets of uranium dioxides. (author) [pt

  3. Well Waters Fluoride in Enugu, Nigeria

    Directory of Open Access Journals (Sweden)

    ISI Ogbu

    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.

  4. Fluoride loaded polymeric nanoparticles for dental delivery.

    Science.gov (United States)

    Nguyen, Sanko; Escudero, Carlos; Sediqi, Nadia; Smistad, Gro; Hiorth, Marianne

    2017-06-15

    The overall aim of the present paper was to develop fluoride loaded nanoparticles based on the biopolymers chitosan, pectin, and alginate, for use in dental delivery. First, the preparation of nanoparticles in the presence of sodium fluoride (NaF) as the active ingredient by ionic gelation was investigated followed by an evaluation of their drug entrapment and release properties. Chitosan formed stable, spherical, and monodisperse nanoparticles in the presence of NaF and tripolyphoshate as the crosslinker, whereas alginate and pectin were not able to form any definite nanostructures in similar conditions. The fluoride loading capacity was found to be 33-113ppm, and the entrapment efficiency 3.6-6.2% for chitosan nanoparticles prepared in 0.2-0.4% (w/w) NaF, respectively. A steady increase in the fluoride release was observed for chitosan nanoparticles prepared in 0.2% NaF both in pH5 and 7 until it reached a maximum at time point 4h and maintained at this level for at least 24h. Similar profiles were observed for formulations prepared in 0.4% NaF; however the fluoride was released at a higher level at pH5. The low concentration, but continuous delivery of fluoride from the chitosan nanoparticles, with possible expedited release in acidic environment, makes these formulations highly promising as dental delivery systems in the protection against caries development. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. THE USE OF FLUORIDE AND ITS EFFECT ON HEALTH

    Directory of Open Access Journals (Sweden)

    Domen Kanduti

    2016-07-01

    Full Text Available Appropriate oral health care is fundamental for any individual’s health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. Fluoride occurs naturally in our environment and is always present in our lives. However, the concentration differs from area to area. Exposure can occur through diet, respiration and fluoride supplements. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Drinking water in Slovenia is not fluoridated; the amount of naturally present fluoride is very low. Fluoride can be toxic in extremely high concentrations. The most important effect of fluoride on caries incidence is through its role in the process of remineralisation and demineralisation of tooth enamel. The European Academy of Paediatric Dentistry (EAPD recommends a preventive topical use of fluoride supplements because of their cariostatic effect. 

  6. Electrochemical Extraction of Rare Earth Metals in Molten Fluorides : Conversion of Rare Earth Oxides into Rare Earth Fluorides Using Fluoride Additives

    NARCIS (Netherlands)

    Abbasalizadeh, A.; Malfliet, Annelies; Seetharaman, Seshadri; Sietsma, J.; Yang, Y.

    2017-01-01

    In the present research on rare earth extraction from rare earth oxides (REOs), conversion of rare earth oxides into rare earth fluorides with fluoride fluxes is investigated in order to overcome the problem of low solubility of the rare earth oxides in molten fluoride salts as well as the formation

  7. Method and apparatus for sampling atmospheric mercury

    Science.gov (United States)

    Trujillo, Patricio E.; Campbell, Evan E.; Eutsler, Bernard C.

    1976-01-20

    A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

  8. Mercury analysis in hair

    DEFF Research Database (Denmark)

    Esteban, Marta; Schindler, Birgit Karin; Jiménez, José Antonio

    2015-01-01

    laboratories. Training sessions were organized for field workers and four external quality-assessment exercises (ICI/EQUAS), followed by the corresponding web conferences, were organized between March 2011 and February 2012. ICI/EQUAS used native hair samples at two mercury concentration ranges (0...

  9. Mercury exposure in Ireland

    DEFF Research Database (Denmark)

    Cullen, Elizabeth; Evans, David S; Davidson, Fred

    2014-01-01

    of a study to Coordinate and Perform Human Biomonitoring on a European Scale (DEMOCOPHES) pilot biomonitoring study. METHODS: Hair mercury concentrations were determined from a convenience sample of 120 mother/child pairs. Mothers also completed a questionnaire. Rigorous quality assurance within DEMOCOPHES...

  10. Metabolic models for methyl and inorganic mercury

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, S.R.; Purdue, P.

    1984-03-01

    Following the outbreak of mercury poisoning in Minimata, Japan (1953-60), much work has been done on the toxicology of mercury - in particular methyl mercury. In this paper, the authors derive two compartmental models for the metabolism of methyl mercury and inorganic mercury based upon the data which have been collected since 1960.

  11. Fluoride release and cariostatic potential of orthodontic adhesives with and without daily fluoride rinsing

    NARCIS (Netherlands)

    Chin, Yeen; Sandham, John; Rumachik, Elena N.; Ruben, Jan L.; Huysmans, Marie-Charlotte D. N. J. M.

    2009-01-01

    Introduction: In this study, we aimed to evaluate the fluoride-release profiles and caries lesion development in an enamel model with brackets cemented with 4 orthodontic adhesives with and without daily fluoride exposure. Methods: Four orthodontic adhesives (Ketac Cem mu, 3M ESPE, Seefeld, Germany;

  12. 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

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

    Science.gov (United States)

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

    2014-06-01

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

  14. Fluoride release and recharge abilities of contemporary fluoride-containing restorative materials and dental adhesives.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Koliniotou-Koumpia, Eugenia; Helvatzoglou-Antoniades, Maria; Kotsanos, Nikolaos

    2013-01-01

    The aim of this study was to evaluate the fluoride release of five fluoride-releasing restorative materials and three dental adhesives, before and after NaF solution treatment. Five restorative materials (Fuji IX GP, GC Corp.; Ketac N100, 3M ESPE; Dyract Extra, Dentsply; Beautifil II, Shofu Inc.; Wave, SDI) and three dental adhesives (Stae, SDI; Fluorobond II - Shofu Inc.; Prime & Bond NT, Dentsply) were investigated before and after NaF solution treatment. A fluoride ion-selective electrode was to measure fluoride concentrations. During the 86-day period before NaF solution treatment, Fuji IX GP released the highest amount of fluoride among the restorative materials while Prime & Bond NT was the highest among the dental adhesives. After NaF solution treatment, Fuji IX GP again ranked the highest in fluoride release among the restorative materials while Fluorobond II ranked the highest among dental adhesives. It was concluded that the compositions and setting mechanisms of fluoride-containing dental materials influenced their fluoride release and recharge abilities.

  15. 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

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

    Science.gov (United States)

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

    2008-01-01

    The aim of this in vivo pilot study was to determine the concentration of fluoride retained intra-orally in saliva after flossing with dental floss impregnated with stannous fluoride (SnF(2)). Participants flossed their teeth ad libitum with 2 premeasured lengths of fluoridated dental floss. Expectorated saliva samples were collected in vials before flossing (PF), immediately postflossing(IPF), at 30 minutes (30), and 1 hour (60) after flossing for analysis with a fluoride-specific electrode and an Orion millivoltmeter. Postflossing samples were compared to the preflossing samples using ANOVA and Tukey's HSD. Differences between the PF and IPF group means were found to be statistically significant at pflossing (PF). It can be concluded that fluoride can be released from flossing with the tested SnF(2)-impregnated dental floss elevating salivary fluoride levels for at least 30 minutes. Use of this fluoride-containing dental floss offers an option for delivery of fluoride to individuals at risk for dental caries.

  17. [Mercury in vaccines].

    Science.gov (United States)

    Hessel, Luc

    2003-01-01

    Thiomersal, also called thimerosal, is an ethyl mercury derivative used as a preservative to prevent bacterial contamination of multidose vaccine vials after they have been opened. Exposure to low doses of thiomersal has essentially been associated with hypersensitivity reactions. Nevertheless there is no evidence that allergy to thiomersal could be induced by thiomersal-containing vaccines. Allergy to thiomersal is usually of delayed-hypersensitivity type, but its detection through cutaneous tests is not very reliable. Hypersensitivity to thiomersal is not considered as a contraindication to the use of thiomersal-containing vaccines. In 1999 in the USA, thiomersal was present in approximately 30 different childhood vaccines, whereas there were only 2 in France. Although there were no evidence of neurological toxicity in infants related to the use of thiomersal-containing vaccines, the FDA considered that the cumulative dose of mercury received by young infants following vaccination was high enough (although lower than the FDA threshold for methyl mercury) to request vaccine manufacturers to remove thiomersal from vaccine formulations. Since 2002, all childhood vaccines used in Europe and the USA are thiomersal-free or contain only minute amounts of thiomersal. Recently published studies have shown that the mercury levels in the blood, faeces and urine of children who had received thiomersal-containing vaccines were much lower than those accepted by the American Environmental Protection Agency. It has also been demonstrated that the elimination of mercury in children was much faster than what was expected on the basis of studies conducted with methyl mercury originating from food. Recently, the hypothesis that mercury contained in vaccines could be the cause of autism and other neurological developmental disorders created a new debate in the medical community and the general public. To date, none of the epidemiological studies conducted in Europe and elsewhere

  18. Mercury Information Clearinghouse

    Energy Technology Data Exchange (ETDEWEB)

    Chad A. Wocken; Michael J. Holmes; Dennis L. Laudal; Debra F. Pflughoeft-Hassett; Greg F. Weber; Nicholas V. C. Ralston; Stanley J. Miller; Grant E. Dunham; Edwin S. Olson; Laura J. Raymond; John H. Pavlish; Everett A. Sondreal; Steven A. Benson

    2006-03-31

    The Canadian Electricity Association (CEA) identified a need and contracted the Energy & Environmental Research Center (EERC) to create and maintain an information clearinghouse on global research and development activities related to mercury emissions from coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals{reg_sign} (CATM{reg_sign}) Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive quarterly information updates that provide a detailed assessment of developments in the various areas of mercury monitoring, control, policy, and research. A total of eight topical reports were completed and are summarized and updated in this final CEA quarterly report. The original quarterly reports can be viewed at the CEA Web site (www.ceamercuryprogram.ca). In addition to a comprehensive update of previous mercury-related topics, a review of results from the CEA Mercury Program is provided. Members of Canada's coal-fired electricity generation sector (ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova Scotia Power Inc., Ontario Power Generation, SaskPower, and TransAlta) and CEA, have compiled an extensive database of information from stack-, coal-, and ash-sampling activities. Data from this effort are also available at the CEA Web site and have provided critical information for establishing and reviewing a mercury standard for Canada that is protective of environment and public health and is cost-effective. Specific goals outlined for the CEA mercury program included the following: (1) Improve emission inventories and develop management options through an intensive 2-year coal-, ash-, and stack-sampling program; (2) Promote effective stack testing through the development of guidance material and the support of on-site training on the Ontario Hydro method for employees, government representatives, and contractors on an as-needed basis; (3) Strengthen laboratory analytical capabilities through

  19. Small Mercury Relativity Orbiter

    Science.gov (United States)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  20. Fluoride concentration in urine after silver diamine fluoride application on tooth enamel

    Science.gov (United States)

    Sari, D. L.; Bahar, A.; Gunawan, H. A.; Adiatman, M.; Rahardjo, A.; Maharani, D. A.; Toptanci, I. R.; Yavuz, I.

    2017-08-01

    Silver Diammine Fluoride (SDF), which contains fluoride, is known to inhibit tooth enamel demineralization and increase fluoride concentrations in saliva and urine. The aim of this study is to analyze the fluoride concentration in urine after application of SDF on tooth enamel. Urine from four subjects was collected prior to, 30 minutes after, and two and three hours after the application of SDF, and an ion-selective electrode was used to measure the fluoride concentrations. There was no significant difference between time 1 and time 2, time 1 and time 3, time 1 and time 4, time 2 and 3 (p > 0.05), and there was a significant difference between time 2 and time 4 as well as time 3 and time 4 (p SDF.

  1. 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.

  2. Mercury Phase II Study - Mercury Behavior in Salt Processing Flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Jain, V. [Savannah River Remediation, LLC., Aiken, SC (United States); Shah, H. [Savannah River Remediation, LLC., Aiken, SC (United States). Sludge and Salt Planning; Bannochie, C. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Wilmarth, W. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-25

    Mercury (Hg) in the Savannah River Site Liquid Waste System (LWS) originated from decades of canyon processing where it was used as a catalyst for dissolving the aluminum cladding of reactor fuel. Approximately 60 metric tons of mercury is currently present throughout the LWS. Mercury has long been a consideration in the LWS, from both hazard and processing perspectives. In February 2015, a Mercury Program Team was established at the request of the Department of Energy to develop a comprehensive action plan for long-term management and removal of mercury. Evaluation was focused in two Phases. Phase I activities assessed the Liquid Waste inventory and chemical processing behavior using a system-by-system review methodology, and determined the speciation of the different mercury forms (Hg+, Hg++, elemental Hg, organomercury, and soluble versus insoluble mercury) within the LWS. Phase II activities are building on the Phase I activities, and results of the LWS flowsheet evaluations will be summarized in three reports: Mercury Behavior in the Salt Processing Flowsheet (i.e. this report); Mercury Behavior in the Defense Waste Processing Facility (DWPF) Flowsheet; and Mercury behavior in the Tank Farm Flowsheet (Evaporator Operations). The evaluation of the mercury behavior in the salt processing flowsheet indicates, inter alia, the following: (1) In the assembled Salt Batches 7, 8 and 9 in Tank 21, the total mercury is mostly soluble with methylmercury (MHg) contributing over 50% of the total mercury. Based on the analyses of samples from 2H Evaporator feed and drop tanks (Tanks 38/43), the source of MHg in Salt Batches 7, 8 and 9 can be attributed to the 2H evaporator concentrate used in assembling the salt batches. The 2H Evaporator is used to evaporate DWPF recycle water. (2) Comparison of data between Tank 21/49, Salt Solution Feed Tank (SSFT), Decontaminated Salt Solution Hold Tank (DSSHT), and Tank 50 samples suggests that the total mercury as well as speciated

  3. Mercury Phase II Study - Mercury Behavior in Salt Processing Flowsheet

    International Nuclear Information System (INIS)

    Jain, V.; Shah, H.; Wilmarth, W. R.

    2016-01-01

    Mercury (Hg) in the Savannah River Site Liquid Waste System (LWS) originated from decades of canyon processing where it was used as a catalyst for dissolving the aluminum cladding of reactor fuel. Approximately 60 metric tons of mercury is currently present throughout the LWS. Mercury has long been a consideration in the LWS, from both hazard and processing perspectives. In February 2015, a Mercury Program Team was established at the request of the Department of Energy to develop a comprehensive action plan for long-term management and removal of mercury. Evaluation was focused in two Phases. Phase I activities assessed the Liquid Waste inventory and chemical processing behavior using a system-by-system review methodology, and determined the speciation of the different mercury forms (Hg+, Hg++, elemental Hg, organomercury, and soluble versus insoluble mercury) within the LWS. Phase II activities are building on the Phase I activities, and results of the LWS flowsheet evaluations will be summarized in three reports: Mercury Behavior in the Salt Processing Flowsheet (i.e. this report); Mercury Behavior in the Defense Waste Processing Facility (DWPF) Flowsheet; and Mercury behavior in the Tank Farm Flowsheet (Evaporator Operations). The evaluation of the mercury behavior in the salt processing flowsheet indicates, inter alia, the following: (1) In the assembled Salt Batches 7, 8 and 9 in Tank 21, the total mercury is mostly soluble with methylmercury (MHg) contributing over 50% of the total mercury. Based on the analyses of samples from 2H Evaporator feed and drop tanks (Tanks 38/43), the source of MHg in Salt Batches 7, 8 and 9 can be attributed to the 2H evaporator concentrate used in assembling the salt batches. The 2H Evaporator is used to evaporate DWPF recycle water. (2) Comparison of data between Tank 21/49, Salt Solution Feed Tank (SSFT), Decontaminated Salt Solution Hold Tank (DSSHT), and Tank 50 samples suggests that the total mercury as well as speciated

  4. A mercury transport and fate model (LM2-mercury) for mass budget assessment of mercury cycling in Lake Michigan

    Science.gov (United States)

    LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

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

    Science.gov (United States)

    Hardt, H; Lamport, D T

    1982-04-01

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

  6. Mercury Exposure and Heart Diseases.

    Science.gov (United States)

    Genchi, Giuseppe; Sinicropi, Maria Stefania; Carocci, Alessia; Lauria, Graziantonio; Catalano, Alessia

    2017-01-12

    Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system.

  7. Mercury Exposure and Heart Diseases

    Directory of Open Access Journals (Sweden)

    Giuseppe Genchi

    2017-01-01

    Full Text Available Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system.

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

    Science.gov (United States)

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

    2017-11-01

    Fluoride has been widely used for the prevention of dental caries since the mid-20th century. The aim of this study was to investigate the chronologic trends in studies on fluoride mechanisms of action against dental caries during the years 1950 to 2015. To this aim, queries such as "fluoride," "fluoride and demineralization," "fluoride and remineralization," "fluoride and (plaque or biofilms)," and "fluoride and (bacteria or microbials)" were submitted to PubMed to collect research article information, including titles, abstracts, publication dates, author affiliations, and publication journals. The article information that PubMed produced was then collected by an automatic web crawler and examined through informetrics and linguistic analyses. We found that the number of articles concerned with fluoride mechanisms of action against dental caries was 6,903 and gradually increased over time during the years 1950 to 2015. They were published by 1,136 journals-most notably, Caries Research and Journal of Dental Research. Of the articles published, those related to bacteria/microbials had a higher percentage (44%) than those dealing with plaque/biofilms, demineralization, and remineralization. With regard to the geographic distribution of authors, Europe and North America accounted for 65% of the articles during the years 1987 to 2015, although the number of authors in Asia sharply increased in recent years. Among the fluoride compounds, NaF was mentioned more frequently than SnF 2 , Na 2 PO 3 F, amine fluoride, and acidulated phosphate fluoride during the years 1986 to 2015. Water fluoridation received the most attention among the various fluoride application methods (toothpastes, mouthwashes, fluoride varnishes, and fluoride gels) during the same period. These results, obtained from employing informetrics and linguistic analyses, suggest that in studies on fluoride mechanisms of action, 1) the unbalanced geographic distribution of articles and 2) the heavy

  9. Mercury's exosphere: observations during MESSENGER's First Mercury flyby.

    Science.gov (United States)

    McClintock, William E; Bradley, E Todd; Vervack, Ronald J; Killen, Rosemary M; Sprague, Ann L; Izenberg, Noam R; Solomon, Sean C

    2008-07-04

    During MESSENGER's first Mercury flyby, the Mercury Atmospheric and Surface Composition Spectrometer measured Mercury's exospheric emissions, including those from the antisunward sodium tail, calcium and sodium close to the planet, and hydrogen at high altitudes on the dayside. Spatial variations indicate that multiple source and loss processes generate and maintain the exosphere. Energetic processes connected to the solar wind and magnetospheric interaction with the planet likely played an important role in determining the distributions of exospheric species during the flyby.

  10. Recovery of mercury from acid waste residues

    Science.gov (United States)

    Greenhalgh, Wilbur O.

    1989-12-05

    Mercury can be recovered from nitric acid-containing fluids by reacting the fluid with aluminum metal to produce mercury metal, and then quenching the reactivity of the nitric acid prior to nitration of the mercury metal.

  11. Mercury Poisoning Linked to Skin Products

    Science.gov (United States)

    ... Products For Consumers Home For Consumers Consumer Updates Mercury Poisoning Linked to Skin Products Share Tweet Linkedin ... and, in some situations, criminal prosecution. Dangers of Mercury Exposure to mercury can have serious health consequences. ...

  12. Viscosity of Molten Alkaline-Earth Fluorides

    Science.gov (United States)

    Takeda, Osamu; Hoshino, Yosuke; Anbo, Yusuke; Yanagase, Kei-ichi; Aono, Masahiro; Sato, Yuzuru

    2015-04-01

    The viscosities of molten alkaline-earth fluorides were measured using the oscillating crucible method, which is especially suitable for measuring molten salts with low viscosity. The results showed a good Arrhenius linearity over a wide temperature range. The measured viscosities and activation energies increased in the following order: . Judging by the charge density, the viscosity of alkaline-earth fluorides should increase from molten to . However, the results indicate a different tendency, which may be explained by a Coulomb force that is very strong. The low viscosity of can be attributed to a decreased cohesive force, due to a partial loss of the Coulomb force caused by a higher charge density of the material. The viscosities were also compared to those of molten alkali fluorides and alkaline-earth chlorides. The viscosities of molten alkaline-earth fluorides were higher than those of molten alkali fluorides and alkaline-earth chlorides. The viscosity determined in this study was compared to literature values and showed a reasonable value in the relatively low-viscosity region.

  13. Emissions of fluorides from welding processes.

    Science.gov (United States)

    Szewczyńska, Małgorzata; Pągowska, Emilia; Pyrzyńska, Krystyna

    2015-11-01

    The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H. Vincent and D. Mark at the Institute of Occupational Medicine (IOM), personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-N-trimethylammonium bromide (CTAB) were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8μg/L and 24μg/L, respectively. The linear range of calibration was 0.01-10mg/L, which corresponds to 0.0001-0.1mg of fluorides per m(3) in collection of a 20L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20-1.82mg/m(3), while the inhalable fraction contained 0.23-1.96mg/m(3) of fluorides during an eight-hour working day in the welding room. Copyright © 2015. Published by Elsevier B.V.

  14. 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.

  15. Thermodynamic data-base for metal fluorides

    International Nuclear Information System (INIS)

    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

  16. Influences of charcoal and bamboo charcoal amendment on soil-fluoride fractions and bioaccumulation of fluoride in tea plants.

    Science.gov (United States)

    Gao, Hongjian; Zhang, Zhengzhu; Wan, Xiaochun

    2012-10-01

    High levels of fluoride in tea plants pose a potential health risk to humans who drink tea. It has been demonstrated that tea plant fluoride is closely related to the available fluoride in soil. But approaches that could be used to regulate the availability of fluoride in soil have been rarely seen. This study aims to investigate how the addition of charcoal and bamboo charcoal affected soil fluoride availability and bioaccumulation of fluoride in tea plants. In a microcosm experiment, tea plants were grown in the tea garden soil mixed with different amounts of charcoal and bamboo charcoal [that is, 0.5, 1.0, 2.5, and 5.0 % (w/w)]. Soil-fluoride fractions and fluoride accumulated in tea plants were determined using the sequential extraction and ion selective electrode method. Obtained results showed that both charcoal and bamboo charcoal additions significantly enhanced the concentrations of Fe/Mn oxide-bound fluoride, but significantly reduced the concentrations of water-soluble and exchangeable fluoride (p Charcoal and bamboo charcoal additions also significantly decreased the amounts of fluoride in tea roots and tea leaves (p charcoal and bamboo charcoal had no impacts on the tea quality, as indexed by the concentrations of polysaccharides, polyphenols, amino acids, and caffeine in tea leaves. These results suggested that application of charcoal and bamboo charcoal may provide a useful method to reduce the availability of fluoride in soil and the subsequent fluoride uptake by tea plants.

  17. State and National Water Fluoridation System (Public Water Systems)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Water Fluoridation Reporting System (WFRS) has been developed to provide tools to assist states in managing fluoridation programs. WFRS is designed to track all...

  18. Mercury, Vaccines, and Autism

    Science.gov (United States)

    Baker, Jeffrey P.

    2008-01-01

    The controversy regarding the once widely used mercury-containing preservative thimerosal in childhood vaccines has raised many historical questions that have not been adequately explored. Why was this preservative incorporated in the first place? Was there any real evidence that it caused harm? And how did thimerosal become linked in the public mind to the “autism epidemic”? I examine the origins of the thimerosal controversy and their legacy for the debate that has followed. More specifically, I explore the parallel histories of three factors that converged to create the crisis: vaccine preservatives, mercury poisoning, and autism. An understanding of this history provides important lessons for physicians and policymakers seeking to preserve the public’s trust in the nation’s vaccine system. PMID:18172138

  19. Mercury in Canadian crude oil

    International Nuclear Information System (INIS)

    Hollebone, B.P.

    2005-01-01

    Estimates for average mercury concentrations in crude oil range widely from 10 ng/g of oil to 3,500 ng/g of oil. With such a broad range of estimates, it is difficult to determine the contributions of the petroleum sector to the total budget of mercury emissions. In response to concerns that the combustion of petroleum products may be a major source of air-borne mercury pollution, Environment Canada and the Canadian Petroleum Products Institute has undertaken a survey of the average total mercury concentration in crude oil processed in Canadian refineries. In order to calculate the potential upper limit of total mercury in all refined products, samples of more than 30 different types of crude oil collected from refineries were measured for their concentration of mercury as it enters into a refinery before processing. High temperature combustion, cold vapour atomic absorption and cold vapour atomic fluorescence were the techniques used to quantify mercury in the samples. The results of the study provide information on the total mass of mercury present in crude oil processed in Canada each year. Results can be used to determine the impact of vehicle exhaust emissions to the overall Canadian mercury emission budget. 17 refs., 2 tabs., 2 figs

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

    Science.gov (United States)

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

    2014-01-01

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

  1. Method for mercury refinement

    Science.gov (United States)

    Grossman, M.W.; Speer, R.; George, W.A.

    1991-04-09

    The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

  2. Apparatus for mercury refinement

    Science.gov (United States)

    Grossman, M.W.; Speer, R.; George, W.A.

    1991-07-16

    The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

  3. Apparatus for mercury refinement

    International Nuclear Information System (INIS)

    Grossman, M.W.; Speer, R.; George, W.A.

    1991-01-01

    The effluent from mercury collected during the photochemical separation of the 196 Hg isotope is often contaminated with particulate mercurous chloride, Hg 2 Cl 2 . The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg 2 Cl 2 contaminant. The present invention is particularly directed to such filtering. 5 figures

  4. Method for scavenging mercury

    Science.gov (United States)

    Chang, Shih-ger [El Cerrito, CA; Liu, Shou-heng [Kaohsiung, TW; Liu, Zhao-rong [Beijing, CN; Yan, Naiqiang [Berkeley, CA

    2009-01-20

    Disclosed herein is a method for removing mercury from a gas stream comprising contacting the gas stream with a getter composition comprising bromine, bromochloride, sulphur bromide, sulphur dichloride or sulphur monochloride and mixtures thereof. In one preferred embodiment the getter composition is adsorbed onto a sorbent. The sorbent may be selected from the group consisting of flyash, limestone, lime, calcium sulphate, calcium sulfite, activated carbon, charcoal, silicate, alumina and mixtures thereof. Preferred is flyash, activated carbon and silica.

  5. Magnetic field of Mercury

    International Nuclear Information System (INIS)

    Jackson, D.J.; Beard, D.B.

    1977-01-01

    The geomagnetic field, suitably scaled down and parameterized, is shown to give a very good fit to the magnetic field measurements taken on the first and third passes of the Mariner 10 space probe past Mercury. The excellence of the fit to a reliable planetary magnetospheric model is good evidence that the Mercury magnetosphere is formed by a simple, permanent, intrinsic planetary magnetic field distorted by the effects of the solar wind. The parameters used for a best fit to all the data are (depending slightly on the choice of data) 2.44--2.55 for the ratio of Mercury's magnetic field strength at the subsolar point to that of the earth's subsolar point field (this results in a dipole moment of 170 γR/sub M/ 3 (R/sub M/ is Mercury Radius), i.e., 2.41 x 10 22 G cm 3 in the same direction as the earth's dipole), approx.-113 γR/sub M/ 4 for the planetary quadrupole moment parallel to the dipole moment, 10degree--17degree for the tilt of the planet dipole toward the sun, 4.5degree for the tilt of the dipole toward dawn, and 2.5degree--7.6degree aberration angle for the shift in the tail axis from the planet-sun direction because of the planet's orbital velocity. The rms deviation overall for the entire data set compared with the theoretical fitted model for the magnetic field strength was 17 γ (approx.4% of the maximum field measured). If the data from the first pass that show presumed strong time variations are excluded, the overall rms deviation for the field magnitude is only 10 γ

  6. The planet Mercury (1971)

    Science.gov (United States)

    1972-01-01

    The physical properties of the planet Mercury, its surface, and atmosphere are presented for space vehicle design criteria. The mass, dimensions, mean density, and orbital and rotational motions are described. The gravity field, magnetic field, electromagnetic radiation, and charged particles in the planet's orbit are discussed. Atmospheric pressure, temperature, and composition data are given along with the surface composition, soil mechanical properties, and topography, and the surface electromagnetic and temperature properties.

  7. HOUSEHOLD PURIFICATION OF FLUORIDE CONTAMINATED MAGADI (TRONA)

    DEFF Research Database (Denmark)

    Nielsen, Joan Maj; Dahi, Elian

    1997-01-01

    Purification of fluoride contaminated magadi is studied using bone char sorption and calcium precipitation. The bone char treatment is found to be workable both in columns and in batches where the magadi is dissolved in water prior to treatment. The concentrations in the solutions were 89 g magadi....../L and 95 and 400 mg F/L respectively in natural and synthetic solutions. The fluoride removal capacities observed were 4.6 mg F/g bone char for the column system and 2.7 mg F/g bone char for the batch system in case of synthetic magadi solution. It is however concluded that the batch system is the best...... treatment method. A procedure for purification of fluoride contaminated magadi at household level is described....

  8. Preparation of uranium ingots from double fluorides

    International Nuclear Information System (INIS)

    Le Boulbin, E.

    1967-05-01

    A simple method has been developed for the preparation of uranium double fluorides and has given a new impetus to the study of the reduction of these compounds with a view to obtaining very pure uranium ingots. This reduction can be carried out using calcium or magnesium as the reducing agent, this latter metal being very interesting from the practical point of view. A comparative study of the heat balances of the reduction processes for the double fluorides and for uranium tetrafluoride has shown that reduction of the double fluorides is possible. The exact experimental conditions for these reductions have been determined. Our study has shown in particular that the reduction of the double salt UF 4 , CaF 2 by magnesium leads to the production of small (20 to 500 g) samples of high-purity uranium with a yield of 99 per cent. (author) [fr

  9. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  10. Mercury removal sorbents

    Science.gov (United States)

    Alptekin, Gokhan

    2016-03-29

    Sorbents and methods of using them for removing mercury from flue gases over a wide range of temperatures are disclosed. Sorbent materials of this invention comprise oxy- or hydroxyl-halogen (chlorides and bromides) of manganese, copper and calcium as the active phase for Hg.sup.0 oxidation, and are dispersed on a high surface porous supports. In addition to the powder activated carbons (PACs), this support material can be comprised of commercial ceramic supports such as silica (SiO.sub.2), alumina (Al.sub.2O.sub.3), zeolites and clays. The support material may also comprise of oxides of various metals such as iron, manganese, and calcium. The non-carbon sorbents of the invention can be easily injected into the flue gas and recovered in the Particulate Control Device (PCD) along with the fly ash without altering the properties of the by-product fly ash enabling its use as a cement additive. Sorbent materials of this invention effectively remove both elemental and oxidized forms of mercury from flue gases and can be used at elevated temperatures. The sorbent combines an oxidation catalyst and a sorbent in the same particle to both oxidize the mercury and then immobilize it.

  11. 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...

  12. Examination of Reviews-Outcomes of Community Water Fluoridation ...

    African Journals Online (AJOL)

    There is a relationship between the concentration of water fluoridation of quantity higher than 1 ppm and the incidence of dental fluorosis. It was also observed that there is no relationship between fluoridation and cancer or bone fracture, or any other effects. As fluoridation of water is of immense benefit to a community with ...

  13. Fluoride removal performance of phosphoric acid treated lime ...

    African Journals Online (AJOL)

    Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system operations. In the continuous column operations, fluoride removal performance was ...

  14. Fluoride removal performance of phosphoric acid treated lime ...

    African Journals Online (AJOL)

    2010-11-25

    Nov 25, 2010 ... Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system opera- tions. In the continuous column operations, fluoride removal ...

  15. COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

    Science.gov (United States)

    Seaborg, G.T.

    1960-08-01

    A method is given for precipitating alkali metal plutonium fluorides. such as KPuF/sub 5/, KPu/sub 2/F/sub 9/, NaPuF/sub 5/, and RbPuF/sub 5/, from an aqueous plutonium(IV) solution by adding hydrogen fluoride and alkali-metal- fluoride.

  16. 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.

  17. some factors influencing the free fluoride content in black tea

    African Journals Online (AJOL)

    ACSS

    that is more resistant to erosion by plaque acid and demonstrates a lower surface energy which makes plaque adhesion more difficult. However, excessive intake ... fluoride-halide complexes present in the soil decompose into aluminium and fluoride ions, enhancing their availability to tea plants. The free fluoride ion is then ...

  18. Modelling the Effects of Competing Anions on Fluoride Removal by ...

    African Journals Online (AJOL)

    Fe2O3 nano particles supported on functionalized poly-acrylonitrile was prepared. PAN-oxime-nano Fe2O3 was characterized by XRD, FTIR andTEMand used for fluoride adsorption. The adsorption capacity increased with increasing initial fluoride concentration and reaction time. Fluoride-removal performance of ...

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

    Science.gov (United States)

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

    2017-04-27

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

  20. Fluoride levels in commercially available rice in Ethiopia | Tegegne ...

    African Journals Online (AJOL)

    Alkaline fusion was used for sample preparation of six varieties for both the raw rice and rice cooked with tap water and fluoridated water. Fluoride levels ranged from 0.1-5.5 mg/kg in raw rice sample. Rice which was cooked with different fluoride levels of water showed increment depending on the method of cooking.

  1. Fluoride removal studies in water using natural materials : technical ...

    African Journals Online (AJOL)

    ℓ-1 of fluoride was passed through the column and the variation of fluoride removal for a known rate of flow was studied. Correlation analysis of defluoridation capacity with time was done and an attempt has been made to classify them accordingly. The study reveals that red soil has good fluoride removal capacity followed ...

  2. An inter-laboratory comparative study of fluoride determination in ...

    African Journals Online (AJOL)

    South Africa is on the brink of implementation of mandatory fluoridation of municipal water following the final approval by Parliament in 2001. The ability to accurately measure fluoride in water is an obvious prerequisite for the safe and effective implementation of water fluoridation. This paper evaluates the current status of ...

  3. The accuracy of fluoride measurement in water and its implications ...

    African Journals Online (AJOL)

    The accurate measurement of the fluoride concentration in water is an essential prerequisite to stay within the allowable dosing tolerances required by the South African water fluoridation legislation. In the absence of reliable error estimates for fluoride measurement in natural water samples, a study was conducted utilising ...

  4. Geographical mapping of fluoride levels in drinking water sources in ...

    African Journals Online (AJOL)

    Background: Knowledge of fluoride levels in drinking water is of importance in dental public health, yet this information is lacking, at national level, in Nigeria. Objective: To map out fluoride levels in drinking water sources in Nigeria. Materials and Methods: Fluoride levels in drinking water sources from 109 randomly ...

  5. Spatial analysis of fluoride concentrations in drinking water and ...

    African Journals Online (AJOL)

    Namibia, the driest country in sub-Saharan Africa, is largely reliant on groundwater for its potable water demand and groundwater is a major source of naturally-occurring fluoride. This study assessed the spatial distribution of fluoride in potable water and appraised the population at risk for high fluoride intake. Analysis of ...

  6. Fluoride removal from aqueous solution by pumice: case study on ...

    African Journals Online (AJOL)

    The fluoride removal from synthetic water by pumice was studied at batch experiments in this study. The effect of pH, contact time, fluoride concentration and adsorbent dose on the fluoride sequestration was investigated. The optimum conditions were studied on Kuhbonan water as a case study. The results showed that ...

  7. 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 use...

  8. Graphite Fluoride Fiber Composites For Heat Sinking

    Science.gov (United States)

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

    1989-01-01

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

  9. Fabrication of dense panels in lithium fluoride

    International Nuclear Information System (INIS)

    Farcy, P.; Roger, J.; Pointud, R.

    1958-04-01

    The authors report a study aimed at the fabrication of large and dense lithium fluoride panels. This sintered lithium fluoride is then supposed to be used for the construction of barriers of protection against a flow of thermal neutrons. They briefly present the raw material which is used under the form of chamotte obtained through a pre-sintering process which is also described. Grain size measurements and sample preparation are indicated. Shaping, drying, and thermal treatment are briefly described, and characteristics of the sintered product are indicated

  10. Giant flexoelectricity in polyvinylidene fluoride films

    Energy Technology Data Exchange (ETDEWEB)

    Baskaran, Sivapalan; Ramachandran, Narayanan; He Xiangtong; Thiruvannamalai, Sankar; Lee, Ho Joon; Heo, Hyun [Department of Mechanical and Aerospace Engineering, State University of New York, Buffalo, NY 14260 (United States); Chen Qin [GE Global Research Center, 1 Research Circle, Niskayuna, NY 12309 (United States); Fu, John Y., E-mail: youweifu@buffalo.ed [Department of Mechanical and Aerospace Engineering, State University of New York, Buffalo, NY 14260 (United States)

    2011-05-16

    Recent studies have shown that giant flexoelectricity may exist in certain elastomers with bent-core molecular structures, which contradicts the previous theoretical estimation that the flexoelectric coupling is small in those materials. In this Letter, we report an analogous phenomenon, i.e., the giant direct flexoelectric effect, observed in a polyvinylidene fluoride (PVDF) film. Our experimental studies indicate that such an enhanced flexoelectric effect might be induced by the interaction between the energy couplings of the apolar and the polar molecular structures of the polymer film under elastic deformation. - Highlights: Polyvinylidene fluoride (PVDF) film with not fully crystallized {alpha}- and {beta}-phases. Flexoelectric measurement. Giant direct flexoelectric effect in PVDF.

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

    Science.gov (United States)

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

    2016-04-01

    Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Mercury's Magnetic Field

    Science.gov (United States)

    Johnson, C. L.

    2014-12-01

    Mercury is the only inner solar system body other than Earth to possess an active core dynamo-driven magnetic field and the only planet with a small, highly dynamic magnetosphere. Measurements made by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have provided a wealth of data on Mercury's magnetic field environment. Mercury's weak magnetic field was discovered 40 years ago by the Mariner 10 spacecraft, but its large-scale geometry, strength and origin could not be definitively established. MESSENGER data have shown that the field is dynamo-generated and can be described as an offset axisymmetric dipole field (hereafter OAD): the magnetic equator lies ~0.2 RM (RM = 2440 km) north of the geographic equator and the dipole moment is 2.8 x1019 Am2 (~0.03% that of Earth's). The weak internal field and the high, but variable, solar wind ram pressure drive vigorous magnetospheric dynamics and result in an average distance from the planet center to the sub-solar magnetopause of only 1.42 RM. Magnetospheric models developed with MESSENGER data have allowed re-analysis of the Mariner 10 observations, establishing that there has been no measureable secular variation in the internal field over 40 years. Together with spatial power spectra for the OAD, this provides critical constraints for viable dynamo models. Time-varying magnetopause fields induce secondary core fields, the magnitudes of which confirm the core radius estimated from MESSENGER gravity and Earth-based radar data. After accounting for large-scale magnetospheric fields, residual signatures are dominated by additional external fields that are organized in the local time frame and that vary with magnetospheric activity. Birkeland currents have been identified, which likely close in the planetary interior at depths below the base of the crust. Near-periapsis magnetic field measurements at altitudes greater than 200 km have tantalizing hints of crustal fields, but crustal

  13. Effects of tannin-fluoride and milk-fluoride mixture on human enamel erosion from inappropriately chlorinated pool water.

    Science.gov (United States)

    Boonviriya, Sumalee; Tannukit, Sissada; Jitpukdeebodintra, Suwanna

    2017-01-01

    This in vitro study aimed to investigate the efficacy of tannin-fluoride and milk-fluoride mixtures on human enamel erosion after exposure to inappropriately chlorinated pool water. Enamel specimens were immersed in swimming pool water (pH 2.7) for 30 min and in each test reagent for 4 min once a day for 60 consecutive days (group I: control, group II: tannin-fluoride, group III: milk-fluoride, group IV: tannin-fluoride before and milk-fluoride after erosive challenge, and group V: milk containing tannin-fluoride before and after erosive exposure). Surface microhardness was assessed on days 0, 30, and 60. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were performed after treatment of samples for 60 days. Surface microhardness of experimental groups was ranked as follows: group III > group IV-group V > group II > group I (P erosive enamel surface after treatment with tannin-fluoride and milk-fluoride mixtures. Furthermore, EPMA profiles showed decrease of phosphorus and increase of fluoride content in groups II and IV. In conclusion, we demonstrated that treatment with fluoridated milk with or without tannin-fluoride has protective effects against enamel erosion caused by low-pH swimming pool water.

  14. 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.

  15. Caries development after substitution of supervised fluoride rinses and toothbrushings by unsupervised use of fluoride toothpaste.

    Science.gov (United States)

    Karjalainen, S; Eriksson, A L; Ruokola, M; Toivonen, A

    1994-12-01

    In a nonfluoridated community of Finland, where fortnightly fluoride rinsing with 0.2% sodium fluoride has been used for nearly two decades, a total of 313 children 7-8 yr old were recruited and randomly divided into two groups. 206 children completed the 3-yr trial. The control group (n = 94) participated in the rinsing program which included supervised toothbrushings, while the test group (n = 112) received a new fluoride toothpaste tube (0.15% F) for home use every second month. Annual dental recordings, treatment plannings and the treatment itself were all carried out by one clinician. At the end of the study the number of caries-free children of the toothpaste group was lower (P toothpaste may not be a sufficient substitute for the school-based fortnightly fluoride rinses and supervised toothbrushings in caries prevention of children with erupting permanent teeth.

  16. Data on fluoride contents in groundwater of Bushehr province, Iran

    Directory of Open Access Journals (Sweden)

    Sina Dobaradaran

    2018-04-01

    Full Text Available In this article, we measured the levels of fluoride in groundwater. The samples were taken from groundwater in Bushehr's province, Iran. After the collection of samples, the concentration levels of fluoride were determined by the standard SPADNS method using spectrometer. The mean concentration levels of fluoride in water of all stations were higher than the WHO drinking water guideline. Microsoft Office Excel 2016 was used for calculation of mean values. The mean concentration level of fluoride instatement were in the range of 1.52 to 3.64 mg l-1. Keywords: Bushehr, Drinking water, Fluoride, Groundwater, Spectrometer

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

    Science.gov (United States)

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

    2017-06-01

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

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

    Science.gov (United States)

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

    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 50 mg/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">HF(aq)0, AlF2+, AlF2+">AlF2+and AlF30">AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-">AlF4-, FeF2+, FeF2+">FeF2+, MgF+ and BF2(OH)2-">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.

  19. Mercury: Exploration of a Planet

    Science.gov (United States)

    1976-01-01

    The flight of the Mariner 10 spacecraft to Venus and Mercury is detailed in animation and photography. Views of Mercury are featured. Also included is animation on the origin of the solar system. Dr. Bruce C. Murray, director of the Jet Propulsion Laboratory, comments on the mission.

  20. Rotation of the planet mercury.

    Science.gov (United States)

    Jefferys, W H

    1966-04-08

    The equations of motion for the rotation of Mercury are solved for the general case by an asymptotic expansion. The findings of Liu and O'Keefe, obtained by numerical integration of a special case, that it is possible for Mercury's rotation to be locked into a 2:3 resonance with its revolution, are confirmed in detail. The general solution has further applications.

  1. 49 CFR 173.164 - Mercury (metallic and articles containing mercury).

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Mercury (metallic and articles containing mercury... Than Class 1 and Class 7 § 173.164 Mercury (metallic and articles containing mercury). (a) For transportation by aircraft, mercury must be packaged in packagings which meet the requirements of part 178 of...

  2. Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey

    OpenAIRE

    D J Veeresh; Umesh Wadgave

    2014-01-01

    Introduction: The major reason for decline in dental caries across globe is because of widespread use of fluoride dentifrices. For a fluoride dentifrice to be effective in the control of dental caries, an adequate concentration of the fluoride must be soluble. Objective: To assess soluble fluoride and total fluoride content in selected commercial dentifrices in Davangere. Materials and Methods: The soluble fluoride and total fluoride content in six selected commercial dentifrices in Davangere...

  3. Mercury concentration in bivalve molluscs

    Directory of Open Access Journals (Sweden)

    Szkoda Józef

    2015-09-01

    Full Text Available A total of 85 mussel samples of eight species were examined. Analysis of mercury in the freeze-dried samples was carried out by atomic absorption spectrometry method using direct mercury analyser AMA 254. The analytical procedure for determination of mercury was covered by the quality assurance programme of research and participation in national and international proficiency tests. Concentrations of total mercury in all investigated samples were found to be generally low, in the range of 0.033-0.577 mg/kg of dry weight and of 0.003-0.045 mg/kg of wet weight. The results indicate that obtained levels of mercury in bivalve molluscs are not likely to pose a risk to the health of consumers.

  4. Mercury: Beethoven Quadrangle, H-7

    Science.gov (United States)

    2000-01-01

    Mercury: Computer Photomosaic of the Beethoven Quadrangle, H-7 The Beethoven Quadrangle, named for the 19th century classical German composer, lies in Mercury's Equatorial Mercator located between longitude 740 to 1440. The Mariner 10 spacecraft imaged the region during its initial flyby of the planet. The Image Processing Lab at NASA's Jet Propulsion Laboratory produced this photomosaic using computer software and techniques developed for use in processing planetary data. The images used to construct the Beethoven Quadrangle were taken as Mariner 10 flew passed Mercury. The Mariner 10 spacecraft was launched in 1974. The spacecraft took images of Venus in February 1974 on the way to three encounters with Mercury in March and September 1974 and March 1975. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth and the Moon during its mission. The Mariner 10 Mission was managed by the Jet Propulsion Laboratory for NASA's Office of Space Science in Washington, D.C.

  5. 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.

  6. The effect of fluoride application on fluoride release and the antibacterial action of glass ionomers.

    Science.gov (United States)

    Seppä, L; Forss, H; Ogaard, B

    1993-09-01

    The aim of this study was to investigate whether the release of fluoride and the antimicrobial effect of freshly mixed glass ionomers could be prolonged by application of fluoride on aged material. Test slabs of freshly mixed and aged (14 d in water) conventional and silver glass ionomer (Ketac-Fil and Ketac-Silver, Espe, Seefeld, Germany) and composite (Silux Plus, 3M, St. Paul, MN) were fitted into the bottom of a test tube. A layer of S. mutans Ingbritt cells was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% sucrose solution. After the incubation, pH, F, and Ca contents of the fluid phase, and F, Mg, P, and K contents of the cells were determined. The aged glass-ionomer samples were then covered with toothpaste (0.1% F) or with fluoride gel (1.25% F), and the composite samples with fluoride gel. After being thoroughly rinsed, S. mutans cells were incubated on the samples as above. The pH fall was significantly inhibited by freshly mixed glass ionomers, and there were changes in cellular cation and phosphorus contents. Large amounts of fluoride were found in the fluid and cells. For old glass ionomers, no inhibitory effect on pH fall could be seen. Fluoride release had decreased to a low level.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Fluoride varnish or fluoride mouth rinse? A comparative study of two school-based programs.

    Science.gov (United States)

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

    2016-03-01

    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. Clinical controlled trial. The 2-year study was conducted in Public Dental Clinics in a multicultural low-socioeconomic suburban area of Odense, Denmark with an elevated prevalence of caries compared to the city average. 1,018 children (aged 6-12 years) from 9 different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. 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 week (FMR). All children received oral hygiene instructions and comprehensive dental care at the local Public Dental Clinics throughout the study period. Increment of caries lesions in permanent teeth at both cavitated and initial caries levels. The groups were balanced at baseline. After two years, 961 children (94.4%) were reexamined. The FV group showed a mean DMFS increment of 0.36 compared to 0.41 in the FMR group. The corresponding values for initial caries lesions were 0.83 and 0.91 respectively. There were no statistically significant differences in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program.

  8. 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.

    2013-01-01

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

  9. Diffusion of fluoride in bovine enamel

    International Nuclear Information System (INIS)

    Flim, G.J.; Arends, J.; Kolar, Z.

    1976-01-01

    The uptake of 18 F and the penetration of both F and 18 F in bovine enamel was investigated. Sodium fluoride solutions buffered at pH 7 were employed. The uptake of 18 F was measured by a method described by R. Duckworth and M. Braden, Archs. Oral. Biol., 12(1967), pp. 217-230. The penetration concentration profiles of fluoride (F, 18 F) in the enamel were measured by a sectioning technique. The 18 F uptake in enamel was proportional to approximately tsup(3/4); t being the uptake time. The 18 F concentration as a function of the position in the enamel can be described by: c*(x,t) = c 0 *(t)exp[-α*(t)x]. After correction for the initial fluoride concentration in enamel, for unlabelled fluoride the same dependency is obtained. A model based on simultaneous diffusion and chemical reaction in the pores and diffusion into the hydroxyapatite crystallites will be presented. The results show that diffusion coefficients of the pores are approximately equal to 10 -10 cm 2 s -1 and in the apatite crystallites approximately equal to 10 -17 cm 2 s -1 . The limitations and the approximations of the model are discussed

  10. Geochemical assessment of fluoride enrichment and nitrate ...

    Indian Academy of Sciences (India)

    62

    minerals. By reducing the consumption of fertilizer and stress over groundwater, the water quality can be improved. Key Word- Hydro-geochemistry, Fluoride, ... source (industries effluent, fertilizer industry and fertilizer used in agriculture field) influences ...... groundwater of the Taiyuan basin, Northern China; J. Geochem.

  11. Unconventional fluoride conversion coating preparation and characterization

    Czech Academy of Sciences Publication Activity Database

    Drábiková, J.; Fintová, Stanislava; Tkacz, J.; Doležal, P.; Wasserbauer, J.

    2017-01-01

    Roč. 64, č. 6 (2017), s. 613-619 ISSN 0003-5599 Institutional support: RVO:68081723 Keywords : fluoride conversion coating * magnesium * corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 0.364, year: 2016 http://www.emeraldinsight.com/doi/abs/10.1108/ACMM-02-2017-1757

  12. 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

  13. FLUORIDE REDUCTION FROM WATER BY PRECIPITATION WITH ...

    African Journals Online (AJOL)

    2013-12-31

    Dec 31, 2013 ... standards, which indicated that the consumption of high fluoride water for long periods causes health complications ... has been done with different salts of calcium and determination of optimal conditions of ... temperature T were measured, after that different amount of the same salt was added to each cup .

  14. Fluoride treatment in corticosteroid induced osteoporosis.

    OpenAIRE

    Rejou, F; Dumas, R; Belon, C; Meunier, P J; Edouard, C

    1986-01-01

    Severe osteoporosis with multiple vertebral fractures occurred in two girls receiving prolonged high dose corticosteroids for relapsing dermatomyositis. Sodium fluoride, supplemented with calcium and vitamin D, helped control secondary osteoporosis in one case and should be considered as part of the curative treatment of corticoid induced osteoporosis.

  15. Uranium fluorides analysis. Titanium spectrophotometric determination

    International Nuclear Information System (INIS)

    Anon.

    Titanium determination in uranium hexafluoride in the range 0.7 to 100 microgrammes after transformation of uranium fluoride in sulfate. Titanium is separated by extraction with N-benzoylphenylhydroxylamine, reextracted by hydrochloric-hydrofluoric acid. The complex titanium-N-benzoylphenylhydroxylamine is extracted by chloroform. Spectrophotometric determination at 400 nm [fr

  16. CORRELATION AMONG FLUORIDE AND METALS IN IRRIGATION ...

    African Journals Online (AJOL)

    Preferred Customer

    The levels of fluoride and selected metals in Ethiopian Rift Valley soils and irrigation water in the nearby sources were ... exhaust fumes, process waters and waste from various industrial processes [1]. The uses of ... into four sub-systems: Lake Rudolf, Chew Bahir, the Main Ethiopian Rift (MER) and the Afar. The seismically ...

  17. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride.

    Science.gov (United States)

    Dugheri, Stefano; Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Mucci, Nicola; 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  μ g/filter), and linearity (2.0-4000  μ g/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. 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.

  19. Fluoride in dental biofilm and saliva

    DEFF Research Database (Denmark)

    Larsen, Line Staun

    mellem fluoridkoncentrationerne i biofilmsediment og fordeling af caries mellem regioner. Forskere anbefales at være opmærksomme på de intra-orale forskelle i fluoridkoncentrationer mellem regioner samt sikre balancering af effekten af region, når der indsamles dental biofilm til fluoridanalyse. I det...... biofilmsediment. Dette indikerer at brugen af 5.000 ppm fluorid tandpasta kan føre til forbedret carieskontrol. Det var påfaldende, at en næsten tre en halv ganges forøgelse af fluorideksponeringen kun førte til en fordobling af fluoridbaggrundsniveauerne. Ph.d.-projektets mest overraskende fund er......, at akkumuleringen af fluorid i biofilmsedimentet målt over en time efter en mundskylning med fluorid knapt viste nogen forskel mellem 1.500 og 5.000 ppm fluorid mundskyllevæskerne. Yderligere studier må udforske dette fund og kliniske undersøgelser er påkrævet for at klarlægge de mulige kliniske konsekvenser af de...

  20. ADSORPTIVE REMOVAL OF FLUORIDE FROM WATER USING ...

    African Journals Online (AJOL)

    Preferred Customer

    It requires high capital investment cost and high energy consumption, and is not economical as in the case of the ..... and Temkin isotherm. Freundlich isotherm model assumes unlimited sorption sites which .... energy 13.15 kJ mol-1, which indicates the fluoride removal by nano-AlOOH is chemisorption process. Adsorption ...

  1. Sorption of sulfuryl fluoride by food commodities.

    Science.gov (United States)

    Sriranjini, Venkata-rao; Rajendran, Somiahnadar

    2008-08-01

    The use of sulfuryl fluoride, a structural fumigant for termite and woodborer control, has recently been expanded to treating stored food commodities and food facilities. There is, however, a lack of data on the sorption of sulfuryl fluoride by food commodities. Knowledge about sorption is important in the context of effective treatment and residues. When sulfuryl fluoride was applied at a dose of 50 g m(-3) to various food commodities (total 68) with 300 g per replicate in 0.75 L gas wash bottles (fumigation chambers) at 25 +/- 1 degrees C, in most cases (81%) the gas concentrations in the free space of the commodities exceeded 50 g m(-3) (range 51-80 g m(-3)) at the end of 24 h exposure. In chambers without the substrate, an average concentration of 49.7 g m(-3) was recorded. About 54% of the commodities showed low-level ( 50%). The latter include white oats (terminal gas concentration 17.8 g m(-3)), some of the decorticated split pulses (24.0-29.3 g m(-3)), chickpea flour (26.3 g m(-3)), dried ginger (29.0 g m(-3)), refined wheat flour (30.3 g m(-3)) and coriander powder (40.5 g m(-3)). In unfumigated control commodities, owing to interfering volatiles, Fumiscope readings in the range 0-13 were noted. Sulfuryl fluoride has the advantage of a low or moderate level of sorption with the majority of the food commodities.

  2. Adverse effects of fluoride towards thyroid hormone metabolism

    Directory of Open Access Journals (Sweden)

    Enggar Abdullah Idris MZ

    2008-03-01

    Full Text Available An easily ionized fluoride compound like Sodium Fluoride (NaF has been used thus far as a dental caries prevention substance. However, fluoride ions also have a negative effect because it is very toxic. Several types of research on the effect of fluoride on guinea pigs and human beings indicate the presence synthesis obstruction of T3 and T4 that causes declined production, known as hypothyroidism. Hypothyroidism condition may obstruct tissue growth process and metabolism so as to impact various body organ systems. Preventive efforts against hypothyroidism caused by fluoride include avoiding diffusible fluoride compound intake, like NaF, in a long run systemic use, whereas efforts to overcome fluoride intoxication include consuming food that is rich in calcium, vitamin D, and antioxidant.

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

    Science.gov (United States)

    Rirattanapong, Opas; Rirattanapong, Praphasri

    2016-01-01

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

  4. Human Exposure and Health Effects of Inorganic and Elemental Mercury

    OpenAIRE

    Park, Jung-Duck; Zheng, Wei

    2012-01-01

    Mercury is a toxic and non-essential metal in the human body. Mercury is ubiquitously distributed in the environment, present in natural products, and exists extensively in items encountered in daily life. There are three forms of mercury, i.e., elemental (or metallic) mercury, inorganic mercury compounds, and organic mercury compounds. This review examines the toxicity of elemental mercury and inorganic mercury compounds. Inorganic mercury compounds are water soluble with a bioavailability o...

  5. Methods for dispensing mercury into devices

    Science.gov (United States)

    Grossman, Mark W.; George, William A.

    1987-04-28

    A process for dispensing mercury into devices which requires mercury. Mercury is first electrolytically separated from either HgO or Hg.sub.2 Cl.sub.2 and plated onto a cathode wire. The cathode wire is then placed into a device requiring mercury.

  6. 21 CFR 872.3700 - Dental mercury.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental mercury. 872.3700 Section 872.3700 Food and... DENTAL DEVICES Prosthetic Devices § 872.3700 Dental mercury. (a) Identification. Dental mercury is a device composed of mercury intended for use as a component of amalgam alloy in the restoration of a...

  7. 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.

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

    Science.gov (United States)

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

    2016-07-01

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

  9. 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.

  10. Fluorescent sensor for mercury

    Science.gov (United States)

    Wang, Zidong [Urbana, IL; Lee, Jung Heon [Evanston, IL; Lu, Yi [Champaign, IL

    2011-11-22

    The present invention provides a sensor for detecting mercury, comprising: a first polynucleotide, comprising a first region, and a second region, a second polynucleotide, a third polynucleotide, a fluorophore, and a quencher, wherein the third polynucleotide is optionally linked to the second region; the fluorophore is linked to the first polynucleotide and the quencher is linked to the second polynucleotide, or the fluorophore is linked to the second polynucleotide and the quencher is linked to the first polynucleotide; the first region and the second region hybridize to the second polynucleotide; and the second region binds to the third polynucleotide in the presence of Hg.sup.2+ ions.

  11. Increased mercury emissions from modern dental amalgams

    OpenAIRE

    Bengtsson, Ulf G.; Hylander, Lars D.

    2017-01-01

    All types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor ...

  12. Mercury toxicity and neurodegenerative effects.

    Science.gov (United States)

    Carocci, Alessia; Rovito, Nicola; Sinicropi, Maria Stefania; Genchi, Giuseppe

    2014-01-01

    Mercury is among the most toxic heavy metals and has no known physiological role in humans. Three forms of mercury exist: elemental, inorganic and organic. Mercury has been used by man since ancient times. Among the earliest were the Chinese and Romans, who employed cinnabar (mercury sulfide) as a red dye in ink (Clarkson et al. 2007). Mercury has also been used to purify gold and silver minerals by forming amalgams. This is a hazardous practice, but is still widespread in Brazil's Amazon basin, in Laos and in Venezuela, where tens of thousands of miners are engaged in local mining activities to find and purify gold or silver. Mercury compounds were long used to treat syphilis and the element is still used as an antiseptic,as a medicinal preservative and as a fungicide. Dental amalgams, which contain about 50% mercury, have been used to repair dental caries in the U.S. since 1856.Mercury still exists in many common household products around the world.Examples are: thermometers, barometers, batteries, and light bulbs (Swain et al.2007). In small amounts, some organo mercury-compounds (e.g., ethylmercury tiosalicylate(thimerosal) and phenylmercury nitrate) are used as preservatives in some medicines and vaccines (Ballet al. 2001).Each mercury form has its own toxicity profile. Exposure to Hg0 vapor and MeHg produce symptoms in CNS, whereas, the kidney is the target organ when exposures to the mono- and di-valent salts of mercury (Hg+ and Hg++, respectively)occur. Chronic exposure to inorganic mercury produces stomatitis, erethism and tremors. Chronic MeHg exposure induced symptoms similar to those observed in ALS, such as the early onset of hind limb weakness (Johnson and Atchison 2009).Among the organic mercury compounds, MeHg is the most biologically available and toxic (Scheuhammer et a!. 2007). MeHg is neurotoxic, reaching high levels of accumulation in the CNS; it can impair physiological function by disrupting endocrine glands (Tan et a!. 2009).The most

  13. Mercury kinetics in marine zooplankton

    International Nuclear Information System (INIS)

    Fowler, S.W.; Heyraud, M.; LaRosa, J.

    1976-01-01

    Mercury, like many other heavy metals, is potentially available to marine animals by uptake directly from water and/or through the organisms food. Furthermore, bioavailability, assimilation and subsequent retention in biota may be affected by the chemical species of the element in sea water. While mercury is known to exist in the inorganic form in sea water, recent work has indicated that, in certain coastal areas, a good portion of the total mercury appears to be organically bound; however, the exact chemical nature of the organic fraction has yet to be determined. Methyl mercury may be one constituent of the natural organically bound fraction since microbial mechanisms for in situ methylation of mercury have been demonstrated in the aquatic environment. Despite the fact that naturally produced methyl mercury probably comprises only a small fraction of an aquatic ecosystem, the well-documented toxic effects of this organo-mercurial, caused by man-made introductions into marine food chains, make it an important compound to study

  14. Atmospheric mercury footprints of nations.

    Science.gov (United States)

    Liang, Sai; Wang, Yafei; Cinnirella, Sergio; Pirrone, Nicola

    2015-03-17

    The Minamata Convention was established to protect humans and the natural environment from the adverse effects of mercury emissions. A cogent assessment of mercury emissions is required to help implement the Minamata Convention. Here, we use an environmentally extended multi-regional input-output model to calculate atmospheric mercury footprints of nations based on upstream production (meaning direct emissions from the production activities of a nation), downstream production (meaning both direct and indirect emissions caused by the production activities of a nation), and consumption (meaning both direct and indirect emissions caused by final consumption of goods and services in a nation). Results show that nations function differently within global supply chains. Developed nations usually have larger consumption-based emissions than up- and downstream production-based emissions. India, South Korea, and Taiwan have larger downstream production-based emissions than their upstream production- and consumption-based emissions. Developed nations (e.g., United States, Japan, and Germany) are in part responsible for mercury emissions of developing nations (e.g., China, India, and Indonesia). Our findings indicate that global mercury abatement should focus on multiple stages of global supply chains. We propose three initiatives for global mercury abatement, comprising the establishment of mercury control technologies of upstream producers, productivity improvement of downstream producers, and behavior optimization of final consumers.

  15. Method for removal and stabilization of mercury in mercury-containing gas streams

    Science.gov (United States)

    Broderick, Thomas E.

    2005-09-13

    The present invention is directed to a process and apparatus for removing and stabilizing mercury from mercury-containing gas streams. A gas stream containing vapor phase elemental and/or speciated mercury is contacted with reagent, such as an oxygen-containing oxidant, in a liquid environment to form a mercury-containing precipitate. The mercury-containing precipitate is kept or placed in solution and reacts with one or more additional reagents to form a solid, stable mercury-containing compound.

  16. Dietary fluoride intake from infant and toddler formulas in Poland.

    Science.gov (United States)

    Opydo-Szymaczek, Justyna; Opydo, Jadwiga

    2011-08-01

    Risk of enamel fluorosis associated with excessive fluoride intake during infancy and early childhood has been widely reported in literature. Results of several studies indicate that infant formula consumption, especially in the form of powdered concentrate, may appreciably increase children's fluoride exposure in optimally fluoridated communities. The aim of the study was to measure fluoride content of infant and toddler formulas available in Poland and to discuss implications of the results. Twenty nine brands of powdered formulas were evaluated. Analyzes were performed with the use of ionselective fluoride electrode (09-37 type) and a RAE 111 chloride-silver reference electrode (MARAT). Results revealed that concentration of fluoride in all products was low (mean 29.0 μg/100 g), and that the formula itself is not a significant source of fluoride exposure. However, when reconstituted with water containing more than 0.5 ppm of fluoride, starting formulas and follow-on formulas may provide a daily fluoride intake of above the suggested threshold for fluorosis. Thus, fully formula-fed infants consuming mother milk substitutes prepared with optimally fluoridated water may be at increased risk of dental fluorosis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Effects of different amine fluoride concentrations on enamel remineralization.

    Science.gov (United States)

    Naumova, E A; Niemann, N; Aretz, L; Arnold, W H

    2012-09-01

    The aim of this study was to investigate the effects of decreasing fluoride concentrations on repeated demineralizing challenges on human enamel. In 24 teeth, 3mm×3mm windows were prepared on the buccal and lingual sides and treated in a cycling demineralization-remineralization model. Remineralization was achieved with 100, 10 and 0.1 ppm fluoride from anime fluoride. Coronal sections were cut through the artificial lesions, and three sections per tooth were investigated using polarized light microscopy and scanning electron microscopy with quantitative element analysis. The morphology of the lesions was studied, and the extensions of the superficial layer and the body of the lesion were measured. Using element analysis, the Ca, P and F content were determined. The body of the lesion appeared remineralized after application of 100 ppm fluoride, while remineralization of the lesion was less successful after application of 10 and 0.1 ppm fluoride. The thickness of the superficial layer increased with decreasing fluoride concentrations, and also the extension of the body of the lesion increased. Ca and P content increased with increasing fluoride concentrations. The effectiveness of fluoride in enamel remineralization increased with increasing fluoride concentration. A consistently higher level of fluoride in saliva should be a goal in caries prevention. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2013-07-01

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

  19. Release of fluoride from orthodontic adhesives and penetration into enamel.

    Science.gov (United States)

    Suebsureekul, Panita; Viteporn, Smorntree

    2017-05-01

    The purpose of this work was to compare fluoride release from three orthodontic adhesives and fluoride penetration into the enamel surface. A total of 156 extracted human premolar teeth were randomly assigned to three experimental groups and one control group (without bonding) with 39 teeth per group. Brackets were bonded to teeth using Fuji Ortho LC ® , Illuminate ® , or Light Bond ® . The amount of fluoride released (ppm) into artificial saliva was measured by a fluoride ion-selective electrode connected to an ion analyzer on days 1, 3, 7, and 30. Fluoride penetration was investigated after 1, 2, and 3 months; 13 teeth of each group were randomly selected at every period of study and sectioned across the center of the bracket. The surface of the cross-section was studied under the scanning electron microscope, and the fluoride concentration (weight%) at 1, 2, and 3 µm below the outer enamel surface was determined by energy-dispersive X-ray microanalysis. On days 1, 3, 7, and 30, the mean cumulative fluoride release from the three orthodontic adhesives were significantly different (p fluoride, followed by Fuji Ortho LC ® and Light Bond ® . After 1, 2, and 3 months, fluoride penetration into enamel was only found from Fuji Ortho LC ® . The fluoride concentration decreased with depth but there were no significant differences (p > 0.05) over time at all depths. The in vitro study indicated that fluoride release is a common property of the three fluoride-releasing orthodontic adhesives: Illuminate ® , Fuji Ortho LC ® , and Light Bond ® . However, detectable fluoride penetration is a specific property of Fuji Ortho LC ® . Further clinical studies should be undertaken to investigate the benefit of the two adhesives Illuminate ® and Fuji Ortho LC ® on protection of enamel demineralization.

  20. 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.

  1. Exploring Mercury: The Iron Planet

    OpenAIRE

    Stevenson, David J.

    2004-01-01

    Planet Mercury is both difficult to observe and difficult to reach by spacecraft. Just one spacecraft, Mariner 10, flew by the planet 30 years ago. An upcoming NASA mission, MESSENGER, will be launched this year and will go into orbit around Mercury at the end of this decade. A European mission is planned for the following decade. It's worth going there because Mercury is a strange body and the history of planetary exploration has taught us that strangeness gives us insight into planetary ori...

  2. MESSENGER'S First Flyby of Mercury

    Science.gov (United States)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. An overview of the MESSENGER mission and its January 14th close flyby of Mercury will be provided. Primary science objectives and the science instrumentation will be described. Initial results from MESSENGER'S first flyby on January 14th, 2008 will be discussed with an emphasis on the magnetic field and charged particle measurements.

  3. Distribution and retention of organic and inorganic mercury in methyl mercury-treated neonatal rats

    International Nuclear Information System (INIS)

    Thomas, D.J.; Fisher, H.L.; Sumler, M.R.; Hall, L.L.; Mushak, P.

    1988-01-01

    Seven-day-old Long Evans rats received one mumol of 203 Hg-labeled methyl mercury/kg sc and whole body retention and tissue distribution of organic and inorganic mercury were examined for 32 days postdosing. Neonates cleared mercury slowly until 10 days postdosing when the clearance rate abruptly increased. During the interval when whole body clearance of mercury was extremely slow, methyl mercury was metabolized to inorganic mercury. Peak concentration of mercury in kidney occurred at 2 days postdosing. At 32 days postdosing, 8% of mercury in kidney was in an organic from. Liver mercury concentration peaked at 2 days postdosing and organic mercury accounted for 38% at 32 days postdosing. Brain concentrations of mercury peaked at 2 days postdosing. At 10 days postdosing, organic mercury accounted for 86% of the brain mercury burden, and, at 32 days postdosing, for 60%. The percentage of mercury body burden in pelt rose from 30 to 70% between 1 and 10 days postdosing. At 32 days postdosing pelt contained 85% of the body burden of mercury. At all time points, about 95% of mercury in pelt was in an organic form. Compartmental analysis of these data permitted development of a model to describe the distribution and excretion of organic and inorganic mercury in methyl mercury-treated neonatal rats

  4. Spatial distribution mapping of drinking water fluoride levels in Karnataka, India: fluoride-related health effects.

    Science.gov (United States)

    Chowdhury, Chitta R; Shahnawaz, Khijmatgar; Kumari, Divya; Chowdhury, Avidyuti; Bedi, Raman; Lynch, Edward; Harding, Stewart; Grootveld, Martin

    2016-11-01

    (1) To estimate the concentrations of fluoride in drinking water throughout different zones and districts of the state of Karnataka. (2) To investigate the variation of fluoride concentration in drinking water from different sources, and its relationships to daily temperature and rainfall status in the regional districts. (3) To develop an updated fluoride concentration intensity map of the state of Karnataka, and to evaluate these data in the context of fluoride-related health effects such as fluorosis and their prevalence. Aqueous standard solutions of 10, 100 and 1,000 ppm fluoride (F - ) were prepared with analytical grade Na + /F - and a buffer; TISAB II was incorporated in both calibration standard and analysis solutions in order to remove the potentially interfering effects of trace metal ions. This analysis was performed using an ion-selective electrode (ISE), and mean determination readings for n = 5 samples collected at each Karnataka water source were recorded. The F - concentration in drinking water in Karnataka state was found to vary substantially, with the highest mean values recorded being in the north-eastern zone (1.61 ppm), and the lowest in the south-western one (only 0.41 ppm). Analysis of variance (ANOVA) demonstrated that there were very highly significant 'between-zone' and 'between-districts-within-zones' sources of variation (p water source F - levels within this state. The southern part of Karnataka has low levels of F - in its drinking water, and may require fluoridation treatment in order to mitigate for dental caries and further ailments related to fluoride deficiency. However, districts within the north-eastern region have contrastingly high levels of fluoride, an observation which has been linked to dental and skeletal fluorosis. This highlights a major requirement for interventional actions in order to ensure maintenance of the recommended range of fluoride concentrations (0.8-1.5 ppm) in Karnataka's drinking water

  5. 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.

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

    Science.gov (United States)

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

    2012-01-01

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswicthes, 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 Mg2+ ions, which in turn are octahedrally coordinated to waters and five inwardly-pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state defines how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch most likely functions in gene regulation through a transcription termination mechanism. PMID:22678284

  7. 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.

  8. Giant flexoelectricity in polyvinylidene fluoride films

    International Nuclear Information System (INIS)

    Baskaran, Sivapalan; Ramachandran, Narayanan; He Xiangtong; Thiruvannamalai, Sankar; Lee, Ho Joon; Heo, Hyun; Chen Qin; Fu, John Y.

    2011-01-01

    Recent studies have shown that giant flexoelectricity may exist in certain elastomers with bent-core molecular structures, which contradicts the previous theoretical estimation that the flexoelectric coupling is small in those materials. In this Letter, we report an analogous phenomenon, i.e., the giant direct flexoelectric effect, observed in a polyvinylidene fluoride (PVDF) film. Our experimental studies indicate that such an enhanced flexoelectric effect might be induced by the interaction between the energy couplings of the apolar and the polar molecular structures of the polymer film under elastic deformation. - Highlights: → Polyvinylidene fluoride (PVDF) film with not fully crystallized α- and β-phases. → Flexoelectric measurement. → Giant direct flexoelectric effect in PVDF.

  9. Elimination of mercury in health care facilities.

    Science.gov (United States)

    2000-03-01

    Mercury is a persistent, bioaccumulative toxin that has been linked to numerous health effects in humans and wildlife. It is a potent neurotoxin that may also harm the brain, kidneys, and lungs. Unborn children and young infants are at particular risk for brain damage from mercury exposure. Hospitals' use of mercury in chemical solutions, thermometers, blood pressure gauges, batteries, and fluorescent lamps makes these facilities large contributors to the overall emission of mercury into the environment. Most hospitals recognize the dangers of mercury. In a recent survey, four out of five hospitals stated that they have policies in place to eliminate the use of mercury-containing products. Sixty-two percent of them require vendors to disclose the presence of mercury in chemicals that the hospitals purchase. Only 12 percent distribute mercury-containing thermometers to new parents. Ninety-two percent teach their employees about the health and environmental effects of mercury, and 46 percent teach all employees how to clean up mercury spills. However, the same study showed that many hospitals have not implemented their policies. Forty-two percent were not aware whether they still purchased items containing mercury. In addition, 49 percent still purchase mercury thermometers, 44 percent purchase mercury gastrointestinal diagnostic equipment, and 64 percent still purchase mercury lab thermometers.

  10. The effective use of fluorides in public health

    DEFF Research Database (Denmark)

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

    2005-01-01

    and development was concerned with waterborne fluorides, both naturally occurring and added, and their effects on the prevalence and incidence of dental caries and dental fluorosis. In the latter half of the 20th century, the focus of research was on fluoride toothpastes and mouth rinses. More recently...... 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......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...

  11. 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. PMID:26487295

  12. Fluoride content of clay minerals and argillaceous earth materials

    Science.gov (United States)

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

    1977-01-01

    A reliable method, utilizing a fluoride ion-selective electrode, is described for the determination of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ±5% at different levels of fluoride concentration.Data are presented for various clay minerals and for the geode kaolinite (125 ppm). The clay stratum immediately overlying a fluorite mineralized zone in southern Illinois was found to have a higher fluoride content than the same stratum in a nonmineralized zone approximately 1 mile away. Nonmarine shales in contact with Australian coals were found to be lower in fluoride content than were marine shales in contact with Illinois coals.It is believed that, in certain instances, peak shifts on DTA curves of similar clay minerals are the result of significant differences in their fluoride content.

  13. Mercury pollution: a transdisciplinary treatment

    National Research Council Canada - National Science Library

    Zuber, Sharon L; Newman, Michael C

    2012-01-01

    .... Also included are smaller case studies, such as the Minamata tragedy, fish consumption, and international treaties"-- "Mercury is the gravest chemical pollutant problem of our time, and this is...

  14. Origin and composition of Mercury

    International Nuclear Information System (INIS)

    Lewis, J.S.

    1988-01-01

    The predictions of the expected range of composition of Mercury at the time of its formation made on the basis of a suite of condensation-accretion models of Mercury spanning a range of condensation temperature and accretion sampling functions appropriate to Mercury are examined. It is concluded that these compositonal models can, if modified to take into account the nonselective loss of most of the silicate component of the planet during accretion, provide compositional predictions for the Weidenschilling (1978, 1980) mechanism for the accretion of a metal-rich Mercury. The silicate portion would, in this case, contain 3.6 to 4.5 percent alumina, roughly 1 percent of alkali oxides, and between 0.5 and 6 percent FeO

  15. Fluoride complexation of rutherfordium (Rf, element 104)

    International Nuclear Information System (INIS)

    Strub, E.; Kratz, J.V.; Kronenberg, A.; Naehler, A.; Thoerle, P.; Zauner, S.; Bruechle, W.; Jaeger, E.; Schaedel, M.; Schausten, B.; Schimpf, E.; Zongwei, L.; Kirbach, U.; Schumann, D.; Jost, D.; Tuerler, A.; Asai, M.; Nagame, Y.; Sakama, M.; Tsukada, K.; Gaeggeler, H.W.; Glatz, J.P.

    2000-01-01

    The fluoride complexation of the group-4 elements Zr, Hf and Rf, and of the pseudo-homolog Th, has been investigated in mixed HNO 3 /HF solutions by studying K d values on both cation exchange resins (CIX) and anion exchange resins (AIX) using the automated rapid chemistry apparatus ARCA. On the CIX, the four elements are strongly retained as cations below 10 -3 M HF. For Zr and Hf, the decrease of the K d values due to the formation of fluoride complexes occurs between 10 -3 M HF and 10 -2 M HF. For Rf and Th, this decrease is observed at one order of magnitude higher HF concentrations. On the AIX, for Zr and Hf, a rise of the K d values due to the formation of anionic fluoride complexes is observed between 10 -3 M HF and 10 -2 M HF, i.e. in the same range of HF concentrations where the decrease of the K d values on the CIX is observed, yielding a consistent picture. For Rf and Th, on the AIX, no rise of the K d values is observed even if the HF concentration is increased up to 1 M. By varying the concentration of the counter ion NO 3 - which is competing for the binding sites on the AIX resin, it could be shown, nevertheless, that Rf does form anionic fluoride complexes. Apparently, there is a more specific competition of NO 3 - with respect to [RfF x ] (x-4)- than with [ZrF y ] (y-4)- and [HfF z ] (z-4)- . (orig.)

  16. Localized surface plasmon resonance mercury detection system and methods

    Science.gov (United States)

    James, Jay; Lucas, Donald; Crosby, Jeffrey Scott; Koshland, Catherine P.

    2016-03-22

    A mercury detection system that includes a flow cell having a mercury sensor, a light source and a light detector is provided. The mercury sensor includes a transparent substrate and a submonolayer of mercury absorbing nanoparticles, e.g., gold nanoparticles, on a surface of the substrate. Methods of determining whether mercury is present in a sample using the mercury sensors are also provided. The subject mercury detection systems and methods find use in a variety of different applications, including mercury detecting applications.

  17. Fluoride varnish may improve white spot lesions.

    Science.gov (United States)

    Stafford, Gary L

    2011-12-01

    A randomised, parallel-group, controlled clinical trial. The test group had fluoride varnish applied onto the tooth surfaces with WSLs using a miniature cotton swab or brush and advised not to brush for four hours. The control group had saline solution applied. Status of the WSLs were assessed using a DIAGNOdent pen (KaVo, Biberach, Germany). Of the 110 participants recruited, 14 dropped out between the debonding and the six-month recall visit. There were statistically significant differences between the mean DIAGNOdent readings of the two groups at the three-month (P<0.05) and at the six-month follow-up visits (P<0.01). No adverse response or safety concerns in the use of fluoride varnish were reported by any of the subjects. A greater decrease in DIAGNOdent pen readings was found in the test group during the first six months after debonding. This may be taken to imply an improvement in the WSLs. Thus, topical fluoride varnish application appears to be a good method to treat WSLs and should be advocated as a routine measure after orthodontic treatment.

  18. Biological effects data: Fluoride and sulfur dioxide

    Energy Technology Data Exchange (ETDEWEB)

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

    1975-04-01

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

  19. Mercury Toolset for Spatiotemporal Metadata

    Science.gov (United States)

    Devarakonda, Ranjeet; Palanisamy, Giri; Green, James; Wilson, Bruce; Rhyne, B. Timothy; Lindsley, Chris

    2010-06-01

    Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily)harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

  20. Mercury Toolset for Spatiotemporal Metadata

    Science.gov (United States)

    Wilson, Bruce E.; Palanisamy, Giri; Devarakonda, Ranjeet; Rhyne, B. Timothy; Lindsley, Chris; Green, James

    2010-01-01

    Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily) harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

  1. 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......, a possible residual effect of fluoride cannot be excluded. However, any major carcinogenic effect of heavy fluoride exposure would be very unlikely....

  2. 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 fo......, a possible residual effect of fluoride cannot be excluded. However, any major carcinogenic effect of heavy fluoride exposure would be very unlikely....

  3. Onderzoek naar de bepaling van fluoride in een doorstroomsysteem

    OpenAIRE

    Neele J; Nagtegaal-Wouterse GWM; Reijnders HFR

    1989-01-01

    Een snelle methode voor de bepaling van fluoride in een doorstroomsysteem met potentiometrische detectie en een lage onderste analysegrens is ontwikkeld. De mate waarin fluoride uit fluoride-verbindingen wordt vrijgemaakt door complexvormende stoffen is gevolgd om vast te stellen hoeveel tijd hiervoor nodig is. Enkele methode-karakteristieken zoals herhaalbaarheid, onderste analysegrens, bovenste analysegrens, storing door enige componenten en vergelijkbaarheid zijn bepaald. In een volume van...

  4. Approaches to the accurate characterization of high purity metal fluorides and fluoride glasses

    Science.gov (United States)

    Beary, E. S.; Paulsen, P. J.; Rains, T. C.; Ewing, K. J.; Jaganathan, J.; Aggarwal, I.

    1990-11-01

    The analytical challenges posed by the measurement of trace contaminants in high purity metal fluorides require that innovative chemical preparation procedures be used to enhance existing instrumental techniques. The instrumental techniques used to analyze these difficult matrices must be sensitive enough to detect extremely low levels of trace impurities, and the background interferences derived from the matrix (metal fluoride or glass) must be minimized. A survey of analytical techniques that have the necessary characteristics to analyze these materials will be given. In addition, means of controlling the chemical blank will be presented. Mass and atomic spectrometric techniques will be discussed, specifically graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Analytical procedures using GFAAS and ICP-MS have been developed to determine sub ppb (part per billion) levels of contaminants in high purity fluoride materials.

  5. 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

    on first-order reaction with respect to the concentration of fluoride. The rate constant is directly proportional to the dosage. The model takes into accounts the lag time observed. The kinetical model can be described for any given dosage and initial fluoride concentration in the water. The reaction rate...... parameter, K, varies however slightly for different initial concentrations of fluoride in the water and different dosage of calcined magnesia. These relationships are described separately by two linear equations. It is discussed that the observed lag time is due to the fact that magnesia cannot remove...... fluoride without hydrolysis, and it is probably this hydrolysis which constraint the start of the removal....

  6. 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.

  7. Formulation and Characterization of Antibacterial Fluoride-releasing Sealants

    Science.gov (United States)

    Fan, Yuwei; Townsend, Janice; Wang, Yapin; Lee, Eun Chee; Evans, Katie; Hender, Erica; Hagan, Joseph L.; Xu, Xiaoming

    2013-01-01

    Purpose The purpose of this study was to formulate and characterize experimental antibacterial fluoride-releasing sealants and compare them with commercial sealants for fluoride release, recharge, adhesion, and microleakage. Methods Two experimental sealants (Exp-1, Exp-2) containing a synthesized antibacterial fluoride-releasing monomer and fluoride-releasing filler were formulated. Exp-2 also contained NovaMin nanoparticles. Commercial sealants Clinpro (CL) FluoroShield (FS), and SeLECT Defense (E34) were also included. Fluoride release from disk samples in deionized water was measured daily using an ion-selective electrode for 14 days, and after recharging with Neutra-Foam (2.0% sodium fluoride), fluoride was measured for 5 days. Microtensile bonding strengths (MTBS) to enamel were tested after 24-hour storage in water at 37°C or thermocycling 5-55°C for 1,000 cycles. A microleakage test was conducted on extracted teeth using a dye-penetration method. The data were analyzed using analysis of variance with the Tukey’s honestly significant difference test and Kruskal-Wallis test. Results Exp-1 and Exp-2 had significantly higher fluoride release and recharge capabilities than CL and FL (P<.05). All tested sealants had similar MTBS before and after thermocycling. Exp-2 and Exp-1 had significantly lower microleakage scores (P<.05) than other groups. Conclusion The experimental sealants had higher fluoride release and recharge capabilities and similar or better retention than commercial sealants. PMID:23635887

  8. Fluoride content and labelling of toothpastes marketed in India.

    Science.gov (United States)

    Thakkar, V P; Rao, A; Rajesh, G; Shenoy, R; Pai, M

    2015-09-01

    To enumerate the fluoride content and labelling practices of toothpastes marketed in India and to determine if the content is in accordance with the information provided on the packaging. In vitro analysis of total and free available fluoride in 5 adult and 5 children's fluoride toothpastes in India using fluoride ion electrode. Information on the tube and carton was checked to assess the labelling. The mean Total Fluoride concentrations (TF) in the toothpastes labelled 1,000 ppm, 500ppm and 458 ppm were 1,000, 500 and 449mg/L (sd values 3, 5 and 4mg/L) respectively. The toothpastes' Total Soluble Fluoride (TSF) concentration was generally slightly less than the TF concentration. Overall mean percentage of TSF concentration was 94% sd 9%. The mean percentage of TSF concentration in SMFP (sodium monofluorophosphate)/CaCO3 (calcium carbonate) containing toothpastes was 86% sd 16% while that in NaF (sodium fluoride)/Si (silica) based toothpastes was 98% sd 1% and 95% sd 1% in the remaining toothpastes with unknown abrasive. NaF/Si based toothpastes had more TSF concentration than the others (ptoothpastes. The available fluoride content of one of the ten toothpastes was substantially less than the total fluoride content. Although the toothpastes were labelled following the guidelines of the regulatory body of India, 3 of the 10 failed to mention the abrasive present.

  9. The effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation.

    Science.gov (United States)

    Lippert, Frank

    2017-08-01

    The aim was to investigate the effects of fluoride, strontium, theobromine and their combinations on caries lesion rehardening and fluoridation (EFU) under pH cycling conditions. Human enamel specimens were demineralized at 37°C for 24h using a pH 5.0 solution containing 50mM lactic acid and 0.2% Carbopol 907 which was 50% saturated with respect to hydroxyapatite. Lesions were assigned to nine treatment groups (n=16) based on Knoop surface microhardness indentation length. aqueous solutions were: placebo, 11.9mM sodium fluoride (F), 23.8mM sodium fluoride (2×F), 1.1mM strontium chloride hexahydrate (Sr), 1.1mM F theobromine, Sr+theobromine, F+Sr, F+theobromine, F+Sr+theobromine. Lesions were pH cycled for 5d (daily protocol: 3×1min-treatment; 2×60min-demineralization; 4×60min & overnight-artificial saliva). Knoop indentation length was measured again and%surface microhardness recovery (%SMHr) calculated. EFU was determined using the acid-etch technique. Data were analysed using ANOVA. Model showed fluoride dose-response for both variables (2×F>F>placebo). For%SMHr, F+Sr+/-theobromine resulted in more rehardening than F, however less than 2×F. F+theobromine was similar to F. For EFU, F+Sr was inferior to F, F+theobromine and F+Sr+theobromine which were similar and inferior to 2×F. In absence of fluoride, Sr, theobromine or Sr+theobromine were virtually indistinguishable from placebo and inferior to F. It can be concluded that a) strontium aids rehardening but not EFU and only in presence of fluoride; b) theobromine does not appear to offer any anti-caries benefits in this model; c) there are no synergistic effects between strontium and theobromine in the presence or absence of fluoride. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    BORGES, Fernanda Tavares; CAMPOS, Wagner Reis da Costa; MUNARI, Lais Sant'ana; MOREIRA, Allyson Nogueira; PAIVA, Saul Martins; MAGALHÃES, Claudia Silami

    2010-01-01

    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 highcaries 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 adjacent to

  11. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  12. Autometallographic tracing of mercury in frog liver

    International Nuclear Information System (INIS)

    Loumbourdis, N.S.; Danscher, G.

    2004-01-01

    The distribution of mercury in the liver of the frog Rana ridibunda with the autometallographic method was investigated. The mercury specific autometallographic (HgS/Se AMG ) technique is a sensitive histochemical approach for tracing mercury in tissues from mercury-exposed organisms. Mercury accumulates in vivo as mercury sulphur/mercury selenium nanocrystals that can be silver-enhanced. Thus, only a fraction of the Hg can be visualized. Six animals were exposed for one day and another group of six animals for 6 days in 1 ppm mercury (as HgCI 2 ) dissolved in fresh water. A third group of six animals, served as controls, were sacrificed the day of arrival at the laboratory. First, mercury appears in the blood plasma and erythrocytes. Next, mercury moves to hepatocytes and in the apical part of the cells, that facing bile canaliculi. In a next step, mercury appears in the endothelial and Kupffer cells. It seems likely that, the mercury of hepatocytes moves through bile canaliculi to the gut, most probably bound to glutathione and/or other similar ligands. Most probably, the endothelial and Kupffer cells comprise the first line of defense against metal toxicity. - Frogs can be good bioindicators of mercury

  13. 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

  14. Mercury: Aspects of its ecology and environmental toxicity. [physiological effects of mercury compound contamination of environment

    Science.gov (United States)

    Siegel, S. M.

    1973-01-01

    A study was conducted to determine the effects of mercury pollution on the environment. The possible sources of mercury contamination in sea water are identified. The effects of mercury on food sources, as represented by swordfish, are analyzed. The physiological effects of varying concentrations of mercury are reported. Emphasis is placed on the situation existing in the Hawaiian Islands.

  15. Groundwater Modeling Of Mercury Pollution At A Former Mercury Cell Chlor Alkali Facility In Pavoldar, Kazakhstan

    Science.gov (United States)

    In Kazakhstan, there is a serious case of mercury pollution near the city of Pavlodar from an old mercury cell chlor-alkali plant. The soil, sediment, and water is severly contaminated with mercury and mercury compounds as a result of the industrial activity of this chemical pla...

  16. Effect of brushing on fluoride release from 3 bracket adhesives.

    Science.gov (United States)

    Staley, Robert N; Mack, Steven J; Wefel, James S; Vargas, Marcos A; Jakobsen, Jane R

    2004-09-01

    The purpose of this in vitro study was to compare fluoride ion release from 3 orthodontic bracket adhesives with and without brushing the bracketed teeth with a fluoridated dentifrice. The bracket adhesives included a light-cured composite resin (Transbond; 3M Unitek, Monrovia, Calif), a fluoride-releasing composite resin (Advance; L D Caulk Division, Dentsply International, Milford, Del), and a resin-modified glass ionomer (Fuji Ortho LC; GC America, Alsip, Ill). The teeth in the control group were not bonded with brackets. Sixty extracted human teeth were randomly assigned to 6 groups of 10 each: (1) Transbond, brushed; (2) Advance, brushed; (3) Advance, not brushed; (4) Fuji, brushed; (5) Fuji, not brushed; and (6) control, brushed. After bonding, each tooth was placed in a sealed plastic test tube containing 4 ml of deionized water. The toothpaste used in brushing contained 0.15% weight per volume sodium fluoride, 1500 parts per million parts fluoride (Winter-fresh gel; Colgate-Palmolive Co., New York, NY). Brushing began 24 hours after the teeth were bonded and placed in deionized water. After brushing, the teeth were thoroughly rinsed with deionized water and returned to a sealed test tube. Fluoride measurements were taken before brushing began, at intervals of 72 hours for 22 days, and 90 and 93 days after bonding. Findings included: (1) brushing significantly increased the release of fluoride ions from the teeth in the composite resin and control groups, (2) the enamel crowns of the unbonded control teeth absorbed and re-released a substantial amount of fluoride ions obtained from the toothpaste, (3) the brushed group of teeth bonded with the fluoride-releasing composite resin released significantly more fluoride on the last 4 days that measurements were taken after brushing than the nonbrushed group bonded with the same adhesive, (4) the brushed group of teeth bonded with the resin-modified glass ionomer released significantly more fluoride on the last 4

  17. Sorption of mercury on chemically synthesized polyaniline

    International Nuclear Information System (INIS)

    Remya Devi, P.S.; Verma, R.; Sudersanan, M.

    2006-01-01

    Sorption of inorganic mercury (Hg 2+ ) and methyl mercury, on chemically synthesized polyaniline, in 0.1-10N HCl solutions has been studied. Hg 2+ is strongly sorbed at low acidities and the extent of sorption decreases with increase in acidity. The sorption of methyl mercury is very low in the HCl concentration range studied. Sorption of Hg 2+ on polyaniline in 0.1-10N LiCl and H 2 SO 4 solutions has also been studied. The analysis of the data indicates that the sorption of Hg 2+ depends on the degree of protonation of polyaniline and the nature of mercury(II) chloride complexes in solution. X-ray photoelectron spectroscopy analysis (XPS) of polyaniline sorbed with mercury show that mercury is bound as Hg 2+ . Sorbed mercury is quantitatively eluted from polyaniline with 0.5N HNO 3 . Polyaniline can be used for separation and pre-concentration of inorganic mercury from aqueous samples. (author)

  18. EPA Leadership in the Global Mercury Partnership

    Science.gov (United States)

    The Global Mercury Partnership is a voluntary multi-stakeholder partnership initiated in 2005 to take immediate actions to protect human health and the environment from the releases of mercury and its compounds to the environment.

  19. Mercury-Containing Devices and Demolition

    Science.gov (United States)

    Some items inside residential buildings contain mercury, which poses a persistent and toxic human health and environmental threat. These materials should be carefully salvaged for proper recycling to prevent mercury contamination prior to demolition.

  20. Health Effects of Exposures to Mercury

    Science.gov (United States)

    ... Mercury in Your Environment Contact Us Share Health Effects of Exposures to Mercury Related Health Information for ... About PDF ; discussion starts on page 20) Methylmercury Effects Effects on People of All Ages Exposure to ...

  1. The effect of longterm exposure to mercury on the bacterial community in marine sediment

    DEFF Research Database (Denmark)

    Rasmussen, Lasse Dam; Sørensen, Søren Johannes

    1998-01-01

    Mercury pollution, bacteria, diversity, mercury resistance, antibiotic resistance, plasmid abundance......Mercury pollution, bacteria, diversity, mercury resistance, antibiotic resistance, plasmid abundance...

  2. Method for the removal and recovery of mercury

    Science.gov (United States)

    Easterly, Clay E.; Vass, Arpad A.; Tyndall, Richard L.

    1997-01-01

    The present invention is an enhanced method for the removal and recovery of mercury from mercury-contaminated matrices. The method involves contacting a mercury-contaminated matrix with an aqueous dispersant solution derived from specific intra-amoebic isolates to release the mercury from the mercury-contaminated matrix and emulsify the mercury; then, contacting the matrix with an amalgamating metal from a metal source to amalgamate the mercury to the amalgamating metal; removing the metallic source from the mercury-contaminated matrix; and heating the metallic source to vaporize the mercury in a closed system to capture the mercury vapors.

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

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-01-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), ClO 2 + RuF 6 - , a new compound well idendified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

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

    International Nuclear Information System (INIS)

    Meublat, L.

    1989-10-01

    The synthesis of ruthenium fluorides and oxide fluorides with high oxidation states was attempted from dioxide RuO 2 and tetroxide RuO 4 . Three fluorinating agents were used: fluorine, chlorine trifluoride and krypton difluoride. The reactions were achieved in anhydrous hydrogen fluoride at room temperature. Thus, the reaction of RuO 4 with CIF 3 enabled us to prepare chloryl hexafluororuthenate (V), CIO 2 + RuF 6 - , a new compound well identified by vibrational spectroscopy (infra-red and Raman), the structure of which was determined. The reaction of KrF 2 with RuO 4 gave the oxide tetrafluoride RuOF 4 , the previously published syntheses and properties of which were not in agreement with each other. This compound was definitely characterized here by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. The product of thermal decomposition (70 0 C) of RuOF 4 is presumably RuF 4 since only oxygen is liberated during this decomposition. At last, the reaction of KrF 2 with RuO 2 probably leads to the formation of the new oxide fluoride RuO 2 F 4 . Indeed, no oxygen is given off during this reaction, the chemical analysis of the red-orange coloured solid residue is almost in agreement with the one proposed and its infra-red absorption spectrum indicates the presence of ruthenium-oxygen and ruthenium-terminal and bridging fluorine bonds [fr

  5. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2004-12-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.

  6. Mercury Continuous Emmission Monitor Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John Schabron; Eric Kalberer; Ryan Boysen; William Schuster; Joseph Rovani

    2009-03-12

    Mercury continuous emissions monitoring systems (CEMs) are being implemented in over 800 coal-fired power plant stacks throughput the U.S. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor calibrators/generators. These devices are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 and vacated by a Federal appeals court in early 2008 required that calibration be performed with NIST-traceable standards. Despite the vacature, mercury emissions regulations in the future will require NIST traceable calibration standards, and EPA does not want to interrupt the effort towards developing NIST traceability protocols. The traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued a conceptual interim traceability protocol for elemental mercury calibrators. The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The EPA traceability protocol document is divided into two separate sections. The first deals with the qualification of calibrator models by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the calibrators that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma

  7. Mercury detection with thermal neutrons

    International Nuclear Information System (INIS)

    Bell, Z.W.

    1994-01-01

    This report describes the work performed to design a gauge to detect mercury concealed within walls, floors, pipes, and equipment inside a building. The project arose out of a desire to decontaminate and decommission (D ampersand D) a building in which mercury had been used as part of a chemical process. The building contains plumbing and equipment, some with residual mercury even after draining, sumps, and hollow walls. So that releases of mercury to the environment might be minimized during D ampersand D activities, it was considered advisable to locate pockets of mercury that may have collected in concealed spaces so that they might be drained in a controlled fashion prior to the application of the wrecking ball or sledge hammer. The detection of such pockets within a building presents some problems not ordinarily encountered in a laboratory environment. Often, only a single side of a wall or pipe is accessible. This condition disqualifies transmission gauges (such as conventional x radiography) in which a probe is sent through the volume under test (VUT) from one side and its passage or attenuation is detected on the opposite side. A robust, one-sided system was needed

  8. Mercury bioaccumulation in the Mediterranean

    Directory of Open Access Journals (Sweden)

    Cinnirella S.

    2013-04-01

    Full Text Available This study details mercury pollution within the food chain of the Mediterranean by analysing the most comprehensive mercury dataset available for biota and water measurements. In this study we computed a bioaccumulation factor (BAF for datasets in the existing mercury-related scientific literature, in on-going programs, and in past measurement campaigns. Preliminary results indicate a major lack of information, making the outcome of any assessment very uncertain. Importantly, not all marine eco-regions are (or have ever been covered by measurement campaigns. Most lacking is information associated with the South-Eastern part of the Mediterranean, and in several eco-regions it is still impossible to reconstruct a trophic net, as the required species were not accounted for when mercury measurements were taken. The datasets also have additional temporal sampling problems, as species were often not sampled systematically (but only sporadically during any given sampling period. Moreover, datasets composed of mercury concentrations in water also suffer from similar geographic limitations, as they are concentrated in the North-Western Mediterranean. Despite these concerns, we found a very clear bioaccumulation trend in 1999, the only year where comprehensive information on both methylmercury concentrations in water and biota was available.

  9. Fluoride in black and green tea ( Camellia sinensis ) infusions in ...

    African Journals Online (AJOL)

    The fluoride contents in the infusions of 21 commercially available Ethiopian and imported black and green tea brands; in leaf and bag forms was determined by a fluoride ion-selective electrode method. Of the samples analyzed twelve were products from Ethiopia and the remaining nine were imported tea brands.

  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. 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.

  12. Spectrophotometric determination of fluoride in drinking water using ...

    African Journals Online (AJOL)

    A sensitive spectrophotometric determination of fluoride in drinking water has been developed using aluminium complexes of triphenylmethane dyes (chrome azurol B and malachite green) as spectrophotometric reagents. The method allowed a reliable determination of fluoride in the range of 0.5–4.0 mg·l-1 for chrome ...

  13. Fluoride release by glass ionomer cements, compomer and giomer

    Directory of Open Access Journals (Sweden)

    Sayed Mostafa Mousavinasab

    2009-01-01

    Conclusion:Fuji IX, Fuji VII, Fuji IX Extra, and Fuji II LC released higher amounts of fluoride compared to Beautifil and Dyract Extra in this study. It seems that the extent of the glass ionomer matrix plays an important role in determining the fluoride releasing ability of glass ionomer cement materials.

  14. Fluoride uptake from restorative dental materials by human enamel

    International Nuclear Information System (INIS)

    Forsten, L.; Rytoemaa, I.; Anttila, A.; Keinonen, J.

    1976-01-01

    The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials ; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19 F (p, αγ) 16 O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts 10 6 . All materials, except the composite, increased clearly the fluoride content of the underlying enamel. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel. (author)

  15. Radiation-induced grafting of vinyl fluoride to polyacrylonitrile fibers

    International Nuclear Information System (INIS)

    Asamov, M.K.; Ziyaev, A.L.; Yul'chibaev, A.A.; Usmanov, Kh.U.

    1981-01-01

    Experimental data on gamma-radiation grafting of vinyl fluoride to polyacrylonitrile fibers in the presence of some organic liquids are given. It is shown, that the presence of chloroform vapours in the system produce sensitizing effect. Grafting of vinyl fluoride to polyacrylonitrile fibers considerably increases their thermal stability, lengthening and decreases shrinkage [ru

  16. Study of Fluoride Glasses Devitrification-Based Magnesium ...

    African Journals Online (AJOL)

    The kinetics of devitrification of fluoride glasses stabilized by magnesium fluoride when heated for some time between the glass transition and melting temperatures. The crystallization kinetics of AlF3-YF3-PbF2-CdF2-MgF2 glass prepared by melting the halide powders were studied by differential scanning calorimetry ...

  17. Characterization and fluoride uptake studies of nano-scale iron ...

    African Journals Online (AJOL)

    ... the studied concentration range of 10-30 mg/L. The high loading capacity points towards the potential of this adsorbent for fluoride removal from aqueous streams. Keywords: Fluoride, nano-iron oxide hydroxide, adsorption, kinetics, isotherm study. International Journal of Engineering, Science and Technology, Vol. 2, No.

  18. Studies on the comparative effect of sodium fluoride on collagen ...

    African Journals Online (AJOL)

    use

    2011-12-12

    Dec 12, 2011 ... The fluoride ion comes from the element fluorine. Fluo- rine, the 17th most abundant element in the earth's crust, is a gas and never occurs in a free state in nature. Fluorine exists only in combination with other elements as fluoride compounds, which are constituents of mine- rals in rocks and soil (Dhar and ...

  19. Fluoride distribution in different environmental segments at Hirakud ...

    African Journals Online (AJOL)

    Administrator

    distances from the pollution source. Fluoride levels in surface water varies according to geographical location and proximity to emission sources. Surface water concentrations generally range from 0.01 - 0.3 ppm. Seawater contains more fluoride than fresh water, with concentrations ranging from 1.2 - 1.5 mg/l. Higher levels.

  20. The uptake of hydrogen fluoride by a forest

    International Nuclear Information System (INIS)

    Murphy, C.E. Jr.

    1980-01-01

    A mathematical model of hydrogen fluoride (HF) deposition and accumulation of fluoride in a Eucalyptus rostrata forest has been developed. The model is based on tree physiology and meteorological principles. The data base for the model was derived from a literature survey of the physiological characteristics of E. rostrata and similar eucalyptus species and from current knowledge of meteorological processes in plant canopies

  1. Influence of fluoride on the electrochemical behvior of a new ...

    African Journals Online (AJOL)

    % NaCl as well as in 0.9%NaCl containing fluoride and even in acidified 0.9% NaCl free of fluoride ion. Very low corrosion current densities and high impedance values were obtained, indicating the passive behavior of the alloy. An active state ...

  2. Fluoride removal from water by zirconium (IV) doped chitosan bio ...

    African Journals Online (AJOL)

    Water containing fluoride above 1.5 mg/L leads to health and environmental harms that creates skeletal and dental fluorosis. Adsorption technique prominently removes fluoride from water and its competence is reliant on development of recyclable, environmentally benign adsorbents. Many reported sorbents for ...

  3. Optical detection of sodium salts of fluoride, acetate and phosphate ...

    Indian Academy of Sciences (India)

    cal systems and they are also of health concern.1,2 Many synthetic chromogenic and/or fluorogenic sensors for fluoride ... not applicable in many bio-analytical applications. Of course, colourimetric detection of fluoride in ..... Hursthouse M B, Light M E, Shi A J 2002 Chem. Commun. 758; (c) Camiolo S, Gale P A, Hursthouse.

  4. The occurrence of fluoride in South African groundwater: A water ...

    African Journals Online (AJOL)

    The fluoride data were obtained by extracting fluoride groundwater quality data from DWAF's Water Management Systems (WMS) database. STATISTICA and ARCVIEW were used to process the data. The dental fluorosis data were obtained from a field study conducted by the Department of Health. The degree of dental ...

  5. Potential groundwater contamination by fluoride from two South ...

    African Journals Online (AJOL)

    A study to investigate the fluoride content in two South African phosphogypsums, Kynoch and Omnia, and the potential threat to water sources was undertaken. Kynoch and Omnia phosphogypsums were found to consist of fluoride in the region of 0.12% and 0.03% by mass, respectively. The phosphogypsum samples were ...

  6. Equilibrium Studies of Fluoride Adsorption onto a Ferric Poly ...

    African Journals Online (AJOL)

    Michael Horsfall

    2 CURRENT ADDRESS: Department of Chemistry, Bondo University College, P.O. Box 210 -40601, Bondo, Kenya. 3 Department of ... KEYWORDS: Adsorption isotherms; Equilibrium analysis; Ferric poly−mineral; Fluoride adsorption; Water fluoride .... rapid phase to a maximum of about 75% at 60 min. Similar trends could ...

  7. Fluoride Removal from Water by Reverse Osmosis Membrane

    Directory of Open Access Journals (Sweden)

    Sara Namavar

    2013-09-01

    Full Text Available As fluoride concentration in drinking water is one of the effective parameters in human health, finding the way to remove excess amount of fluoride from drinking water is very important in water supply projects. Today, with developing in technology and finding new methods, the use of membrane technology for producing fresh water get improved. In this study the efficiency of reverse osmosis method to remove fluoride from water was investigated. Initial concentration of fluoride, sulfate and electrical conductivity in feed water and the effect of associated cation with fluoride ion were studied. All tests adapted from “Standard Methods for Examination of Water and Wastewater”. Determination of fluoride concentration was done according the standard SPANDS method by using a spectrophotometer DR/5000. Obtain results show that with increasing in concentration of fluoride and sulfate and electrical conductivity in feed water the efficiency of RO membrane to remove fluoride reduced. In addition, this efficiency for CaF2 was higher than NaF.

  8. Equilibrium Studies of Fluoride Adsorption onto a Ferric Poly ...

    African Journals Online (AJOL)

    African countries along the Great Rift Valley are among areas of the world where excess fluoride in water sources is a major public health problem. In this work, the removal of fluoride (F) from water solutions using a ferric poly-mineral (FPM) from Kenya was therefore studied using batch adsorption experiments. The effect of ...

  9. Household water sources and their contribution towards fluoride ...

    African Journals Online (AJOL)

    Fluoride is regarded as an essential element for the formation of healthy bones and teeth. However, high fluoride levels in drinking water have been associated with high incidences of dental fluorosis. A 1996–1997 study in Njoro Division, Nakuru District, established that the groundwater used for cooking and drinking, ...

  10. Fluoride Analysis. Training Module 5.200.2.77.

    Science.gov (United States)

    Kirkwood Community Coll., Cedar Rapids, IA.

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

  11. 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.; Buisman, J.K.; 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

  12. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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 characte- rized by powder X-ray diffraction, FT–IR spectroscopy, thermal analysis, SEM and TEM. Monophasic cubic.

  13. 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

  14. comparative study of fluoride in alcornea cordifolia and commercial

    African Journals Online (AJOL)

    Quantum

    2013-07-31

    Jul 31, 2013 ... the analysis of cordifolia for fluoride and its percentage composition. ... Krook, 2006) and reduced intelligence in children (Li et al., 1995; Ziang et al., ... Qualitative analysis. Preliminary test for fluoride in A. cordifolia was carried out by drop- wise addition of concentrated sulphuric acid to the extract. An oily.

  15. Mineral resource of the month: mercury

    Science.gov (United States)

    ,

    2012-01-01

    The article offers information on mercury, a mineral commodity used in industrial and small-scale gold mining applications. Mercury has been reported to be used for amalgamation with gold since the Roman times. Mercury from cinnabar from Almadén, Spain has been used by Romans and has been continued to be used through the Middle Ages and the Colonial era.

  16. 40 CFR 721.10068 - Elemental mercury.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Elemental mercury. 721.10068 Section... Substances § 721.10068 Elemental mercury. (a) Definitions. The definitions in § 721.3 apply to this section... elemental mercury (CAS. No. 7439-97-6) is subject to reporting under this section for the significant new...

  17. 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.

  18. Electrorecovery of tantalum in molten fluorides

    International Nuclear Information System (INIS)

    Espinola, A.; Dutra, A.J.B.; Silva, F.T. da

    1988-01-01

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

  19. Scintillation of rare earth doped fluoride nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

    2011-09-12

    The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

  20. Prevention of dental caries through the effective use of fluoride

    DEFF Research Database (Denmark)

    Petersen, Poul Erik

    2016-01-01

    Background: The World Health Organization (WHO) emphasizes that dental caries is a severe public health problem across the world. The current global and regional patterns of dental caries reflect distinct risk profiles of countries which relate to the structure of the society, living conditions......, lifestyles, and the existence of preventive oral health programmes. Research conducted in high income countries documents that systematic use of fluoride reduces the burden of dental caries; such research is scarce in low and middle income countries. Objectives: This article reviews the evidence on effective...... use of fluoride, highlights the public health approach to fluoridation, and clarifies how automatic fluoridation contributes to breaking social inequities in dental caries. Data collection: Scientific publications on fluoride administration stored in PubMed/Medline and caries data from the WHO...

  1. 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...

  2. 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.

  3. How Tiny Collisions Shape Mercury

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    If space rocks are unpleasant to encounter, space dust isnt much better. Mercurys cratered surface tells of billions of years of meteoroid impacts but its thin atmosphere is what reveals its collisional history with smaller impactors. Now new research is providing a better understanding of what were seeing.Micrometeoroids Ho!The inner solar system is bombarded by micrometeoroids, tiny particles of dust (on the scale of a tenth of a millimeter) emitted by asteroids and comets as they make their closest approach to the Sun. This dust doesnt penetrateEarths layers of atmosphere, but the innermost planet of our solar system, Mercury, doesnt have this convenient cushioning.Just as Mercury is affected by the impacts of large meteoroids, its also shaped by the many smaller-scale impacts it experiences. These tiny collisions are thought to vaporize atoms and molecules from the planets surface, which quickly dissociate. This process adds metals to Mercurys exosphere, the planets extremely tenuous atmosphere.Modeling PopulationsDistribution of the directions from which meteoroids originate before impacting Mercurys surface, as averaged over its entire orbit. Local time of 12 hr corresponds to the Sun-facing side. A significant asymmetry is seen between the dawn (6 hrs) and dusk (18 hrs) rates. [Pokorn et al. 2017]The metal distribution in the exosphere provides a way for us to measure the effect of micrometeoroid impacts on Mercury but this only works if we have accurate models of the process. A team of scientists led by Petr Pokorn (The Catholic University of America and NASA Goddard SFC) has now worked to improve our picture of micrometeoroid impact vaporization on Mercury.Pokorn and collaborators argue that two meteoroid populations Jupiter-family comets (short-period) and Halley-type comets (long-period) contribute the dust for the majority of micrometeoroid impacts on Mercury. The authors model the dynamics and evolution of these two populations, reproducing the

  4. 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.

  5. Relationship between enamel fluorosis severity and fluoride content.

    Science.gov (United States)

    Martinez-Mier, Esperanza A; Shone, Devin B; Buckley, Christine M; Ando, Masatoshi; Lippert, Frank; Soto-Rojas, Armando E

    2016-03-01

    Enamel fluorosis is a hypomineralization caused by chronic exposure to high levels of fluoride during tooth development. Previous research on the relationship between enamel fluoride content and fluorosis severity has been equivocal. The current study aimed at comparing visually and histologically assessed fluorosis severity with enamel fluoride content. Extracted teeth (n=112) were visually examined using the Thylstrup and Fejerskov Index for fluorosis. Eruption status of each tooth was noted. Teeth were cut into 100 μm slices to assess histological changes with polarized light microscopy. Teeth were categorized as sound, mild, moderate, or severe fluorosis, visually and histologically. They were cut into squares (2 × 2 mm) for the determination of fluoride content (microbiopsy) at depths of 30, 60 and 90 μm from the external surface. Erupted teeth with severe fluorosis had significantly greater mean fluoride content at 30, 60 and 90 μm than sound teeth. Unerupted teeth with mild, moderate and severe fluorosis had significantly greater mean fluoride content than sound teeth at 30 μm; unerupted teeth with mild and severe fluorosis had significantly greater mean fluoride content than sound teeth at 60 μm, while only unerupted teeth severe fluorosis had significantly greater mean fluoride content than sound teeth at 90 μm. Both erupted and unerupted severely fluorosed teeth presented higher mean enamel fluoride content than sound teeth. Data on fluoride content in enamel will further our understanding of its biological characteristics which play a role in the management of hard tissue diseases and conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Are fluoride releasing dental materials clinically effective on caries control?

    Science.gov (United States)

    Cury, Jaime Aparecido; de Oliveira, Branca Heloisa; dos Santos, Ana Paula Pires; Tenuta, Livia Maria Andaló

    2016-03-01

    (1) To describe caries lesions development and the role of fluoride in controlling disease progression; (2) to evaluate whether the use of fluoride-releasing pit and fissure sealants, bonding orthodontic agents and restorative materials, in comparison to a non-fluoride releasing material, reduces caries incidence in children or adults, and (3) to discuss how the anti-caries properties of these materials have been evaluated in vitro and in situ. The search was performed on the Cochrane Database of Systematic Reviews and on Medline via Pubmed. Caries is a biofilm-sugar dependent disease and as such it provokes progressive destruction of mineral structure of any dental surface - intact, sealed or restored - where biofilm remains accumulated and is regularly exposed to sugar. The mechanism of action of fluoride released from dental materials on caries is similar to that of fluoride found in dentifrices or other vehicles of fluoride delivery. Fluoride-releasing materials are unable to interfere with the formation of biofilm on dental surfaces adjacent to them or to inhibit acid production by dental biofilms. However, the fluoride released slows down the progression of caries lesions in tooth surfaces adjacent to dental materials. This effect has been clearly shown by in vitro and in situ studies but not in randomized clinical trials. The anti-caries effect of fluoride releasing materials is still not based on clinical evidence, and, in addition, it can be overwhelmed by fluoride delivered from dentifrices. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. High Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    Science.gov (United States)

    Weldesenbet, S. F.; Wohnlich, S.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS ( 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (surface system is simulated with sediment-packed column leached by flowing water and applying temporary interruption of flow during the experiment. The result indicated that a sharp increase of fluoride concentration (up to 58mg/kg) observed in leachates before one pore-volume of water eluted from the column. The concentration of leached fluoride consequently declined with the increased flowing pore-volume of water and finally the lowest concentrations of leached fluoride occurred in the end of the experiment. Flow interruption during column leaching experiment causes a noticeable fluoride concentration perturbation due to the heterogeneity of the sediment.

  8. Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    Science.gov (United States)

    Weldesenbet, S. F.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS ( 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (surface system is simulated with sediment-packed column leached by flowing water and applying temporary interruption of flow during the experiment. The result indicated that a sharp increase of fluoride concentration (up to 58mg/kg) observed in leachates before one pore-volume of water eluted from the column. The concentration of leached fluoride consequently declined with the increased flowing pore-volume of water and finally the lowest concentrations of leached fluoride occurred in the end of the experiment. Flow interruption during column leaching experiment causes a noticeable fluoride concentration perturbation due to the heterogeneity of the sediment.

  9. Control of mercury emissions: policies, technologies, and future trends

    OpenAIRE

    Rhee, Seung-Whee

    2015-01-01

    Seung-Whee Rhee Department of Environmental Engineering, Kyonggi University, Suwon, Republic of Korea Abstract: Owing to the Minamata Convention on Mercury and the Global Mercury Partnership, policies and regulations on mercury management in advanced countries were intensified by a mercury phaseout program in the mercury control strategy. In developing countries, the legislative or regulatory frameworks on mercury emissions are not established specifically, but mercury management is designed...

  10. Canadian mercury inventories: the missing pieces

    Energy Technology Data Exchange (ETDEWEB)

    Hagreen, L.A.; Lourie, B.A. [Summerhill Group, Toronto, ON (Canada)

    2004-07-01

    Research was conducted to determine the significance of the deliberate use of mercury in products in Canada and the associated releases from these sources. Through a combination of literature review and new calculations, the reservoir, flux, and releases of mercury from eight product sources were calculated, and these results compared to historical Canadian inventories. Mercury contributions from the waste sector were also assessed and compared to total Canadian mercury releases and to mercury releases from coal-fired generating stations. Results suggest the use and release of mercury associated with its use in products is 4.5 times what previous inventories indicate. Including dental amalgam and sewage sludge, the total releases of mercury to all environmental compartments in Canada totals 20 tonnes per year. This accounts for less than one-half of the 44 tonnes per year of mercury released from mercury waste disposal each year in Canada. Waste mercury contributions from hazardous waste imports, unknown product sources, and incomplete information on the use of mercury in known products may account for this discrepancy. Waste-related mercury releases and transfers for disposal and recycling are 11 times greater than that of electricity generation in Canada. Results indicate that Canadian inventories have underestimated the significance of mercury use and release associated with products, calling into question the current priorities for mercury management. This paper was developed as part of a panel session at the International Joint Commission 'Mercury in the Ecosystem' workshop, February 26-27, 2003, Windsor, ON, Canada, as a complement to the information on Canadian Inventories presented by Luke Trip (Senes Consulting, Ottawa, ON, Canada).

  11. Sodium Velocity Maps on Mercury

    Science.gov (United States)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  12. Apparatus for control of mercury

    Science.gov (United States)

    Downs, William; Bailey, Ralph T.

    2001-01-01

    A method and apparatus for reducing mercury in industrial gases such as the flue gas produced by the combustion of fossil fuels such as coal adds hydrogen sulfide to the flue gas in or just before a scrubber of the industrial process which contains the wet scrubber. The method and apparatus of the present invention is applicable to installations employing either wet or dry scrubber flue gas desulfurization systems. The present invention uses kraft green liquor as a source for hydrogen sulfide and/or the injection of mineral acids into the green liquor to release vaporous hydrogen sulfide in order to form mercury sulfide solids.

  13. Coal fired flue gas mercury emission controls

    CERN Document Server

    Wu, Jiang; Pan, Weiguo; Pan, Weiping

    2015-01-01

    Mercury (Hg) is one of the most toxic heavy metals, harmful to both the environment and human health. Hg is released into the atmosphere from natural and anthropogenic sources and its emission control has caused much concern. This book introduces readers to Hg pollution from natural and anthropogenic sources and systematically describes coal-fired flue gas mercury emission control in industry, especially from coal-fired power stations. Mercury emission control theory and experimental research are demonstrated, including how elemental mercury is oxidized into oxidized mercury and the effect of

  14. Marine biogeochemistry of mercury

    International Nuclear Information System (INIS)

    Gill, G.A.

    1986-01-01

    Noncontaminating sample collection and handling procedures and accurate and sensitive analysis methods were developed to measure sub-picomolar Hg concentrations in seawater. Reliable and diagnostic oceanographic Hg distributions were obtained, permitting major processes governing the marine biogeochemistry of Hg to be identified. Mercury concentrations in the northwest Atlantic, central Pacific, southeast Pacific, and Tasman Sea ranged from 0.5 to 12 pM. Vertical Hg distributions often exhibited a maximum within or near the main thermocline. At similar depths, Hg concentrations in the northwest Atlantic Ocean were elevated compared to the N. Pacific Ocean. This pattern appears to result from a combination of enhanced supply of Hg to the northwest Atlantic by rainfall and scavenging removal along deep water circulation pathways. These observations are supported by geochemical steady-state box modelling which predicts a relatively short mean residence time for Hg in the oceans; demonstrating the reactive nature of Hg in seawater and precluding significant involvement in nutrient-type recyclic. Evidence for the rapid removal of Hg from seawater was obtained at two locations. Surface seawater Hg measurements along 160 0 W (20 0 N to 20 0 S) showed a depression in the equatorial upwelling area which correlated well with the transect region exhibiting low 234 Th/ 238 U activity ratios. This relationship implies that Hg will be scavenged and removed from surface seawater in biologically productive oceanic zones. Further, a broad minimum in the vertical distribution of Hg was observed to coincide with the intense oxygen minimum zone in the water column in coastal waters off Peru

  15. Industrial Applications of Graphite Fluoride Fibers

    Science.gov (United States)

    Hung, Ching-Cheh; Kucera, Donald

    1991-01-01

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

  16. Quantitative Determination of Lattice Fluoride Effects on the Solubility and Crystallinity of Carbonated Apatites with Incorporated Fluoride

    Science.gov (United States)

    Yan, Guang; Moribe, Kunikazu; Otsuka, Makoto; Papangkorn, Kongnara; Higuchi, William I.

    2013-01-01

    The purpose of this study was to evaluate quantitatively the effects of fluoride on the solubility and crystallinity of carbonated apatites (CAPs) after its incorporation into the crystal lattice using the metastable equilibrium solubility (MES) distribution method. Fluoride incorporated CAPs (F-CAPs) of two different carbonate levels (3% and 5%) and fluoride contents from 0 to 20,000 μg/g were synthesized. X-ray diffraction experiments and Rietveld analysis were conducted to obtain crystallite microstrain and unit cell parameters. Acetate buffer MES solution media were prepared at two solution fluoride concentrations (0.2 mg/L and 2.0 mg/L) and at two pHs (5.0 and 5.7). The unit cell a-axis values of the F-CAPs were found to decrease as the fluoride content increased; consistent with the fluoride being incorporated into the crystal lattice. The fluoride concentrations in the MES solution media were high enough to provide a “swamping” effect such that the fluoride released from the F-CAPs during dissolution was minimal in changing the solution fluoride concentration. Employing the MES distribution superposition method, it was shown that the surface complex possessing the fluorapatite (FAP) stoichiometry (Ca10(PO4)6F2) accounted for the MES distribution behavior of all experiments. In addition, the mean pIFAP [the value of −log(aca 10PO46aF2) calculated from ionic activity product based on FAP stoichiometry of the MES dissolution media in which 50% of the F-CAP had dissolved] correlated well with the crystallite microstrain parameters of the F-CAPs. The incorporated fluoride in the F-CAPs showed only modest effects on F-CAP crystallinity and solubility. PMID:23235353

  17. Environmental contamination and risk assessment of mercury from a historic mercury mine located in southwestern China.

    Science.gov (United States)

    Li, Yonghua

    2013-02-01

    A field survey of mercury pollution in environmental media and human hair samples obtained from residents living in the area surrounding the Chatian mercury mine (CMM) of southwestern China was conducted to evaluate the health risks of mercury to local residents. The results showed that mine waste, and tailings in particular, contained high levels of mercury and that the maximum mercury concentration was 88.50 μg g(-1). Elevated mercury levels were also found in local surface water, paddy soil, and paddy grain, which may cause severe health problems. The mercury concentration of hair samples from the inhabitants of the CMM exceeded 1.0 μg g(-1), which is the limit recommended by the US EPA. Mercury concentrations in paddy soil were positively correlated with mercury concentrations in paddy roots, stalks, and paddy grains, which suggested that paddy soil was the major source of mercury in paddy plant tissue. The average daily dose (ADD) of mercury for local adults and preschool children via oral exposure reached 0.241 and 0.624 μg kg(-1) body weight per day, respectively, which is approaching or exceeds the provisional tolerable daily intake. Among the three oral exposure routes, the greatest contributor to the ADD of mercury was the ingestion of rice grain. Open-stacked mine tailings have resulted in heavy mercury contamination in the surrounding soil, and the depth of appreciable soil mercury concentrations exceeded 100 cm.

  18. Mercury accumulation plant Cyrtomium macrophyllum and its potential for phytoremediation of mercury polluted sites.

    Science.gov (United States)

    Xun, Yu; Feng, Liu; Li, Youdan; Dong, Haochen

    2017-12-01

    Cyrtomium macrophyllum naturally grown in 225.73 mg kg -1 of soil mercury in mining area was found to be a potential mercury accumulator plant with the translocation factor of 2.62 and the high mercury concentration of 36.44 mg kg -1 accumulated in its aerial parts. Pot experiments indicated that Cyrtomium macrophyllum could even grow in 500 mg kg -1 of soil mercury with observed inhibition on growth but no obvious toxic effects, and showed excellent mercury accumulation and translocation abilities with both translocation and bioconcentration factors greater than 1 when exposed to 200 mg kg -1 and lower soil mercury, indicating that it could be considered as a great mercury accumulating species. Furthermore, the leaf tissue of Cyrtomium macrophyllum showed high resistance to mercury stress because of both the increased superoxide dismutase activity and the accumulation of glutathione and proline induced by mercury stress, which favorited mercury translocation from the roots to the aerial parts, revealing the possible reason for Cyrtomium macrophyllum to tolerate high concentration of soil mercury. In sum, due to its excellent mercury accumulation and translocation abilities as well as its high resistance to mercury stress, the use of Cyrtomium macrophyllum should be a promising approach to remediating mercury polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Mercury emission monitoring on municipal waste combustion

    International Nuclear Information System (INIS)

    Braun, H.; Gerig, A.

    1991-01-01

    In waste incineration, mercury is the only heavy metal to be released as a gas, mostly as mercury(II) chloride, because of its high volatility. Continuous emission monitoring is possible only when mercury occurs in its elemental form. This paper reports on various possibilities of converting Hg(II) into Hg(0) that has been studied and tested on a laboratory scale and in the TAMARA refuse incineration pilot facility. Continuous mercury emission measurement appears to be possible, provided mercury is converted in the flue gas condensate precipitated. The measuring results obtained on two municipal solid waste and on one sewage treatment sludge incineration plants show that the mercury monitor is a highly sensitive and selective continuously working instrument for mercury emission monitoring

  20. Fate of mercury in the Arctic (FOMA)

    DEFF Research Database (Denmark)

    Skov, H.; Christensen, J.; Asmund, G.

    This report is the final reporting of the project FONA, funded by the Danish Environmental Protection Agency with means from the MIKA/DANCEA funds for Environmental Support to the Arctic Region. The aim of the project is to study the intercompartment mercury transport chain in the arctic area. From...... atmospheric deposition of mercury on sea surfaces to uptake in marine organisms, bio-accumulation, and finally mercury levels in mammals. The studies in the project are focused on the behaviour of mercury during the spring period where special phenomena lead to an enhanced deposition of mercury in the Arctic...... environment, at a time where the marine ecosystem is particularly active. The studies also include a comprehensive time trend study of mercury in top carnivore species. Each of these studies contributes towards establishing the knowledge necessary to develop a general model for transport and uptake of mercury...

  1. Correlation among fluoride and metals in irrigation water and soils of ...

    African Journals Online (AJOL)

    Correlation among fluoride and metals in irrigation water and soils of Ethiopian Rift Valley. ... The fluoride concentrations in water samples were found in the range of 0.14-8.0 mg/L which is below the WHO limit of fluoride concentration for irrigation (less than 10 mg/L). ... KEY WORDS: Fluoride, Metals, Water, Soil, Ethiopia.

  2. Mercury in the environment : a review

    International Nuclear Information System (INIS)

    Goodarzi, F.

    2000-01-01

    Both geogenic and anthropogenic sources are responsible for the input of mercury into the environment. However, mercury comes mostly from geogenic sources and is found naturally in air, water and soil. Crustal degassing results in emission of mercury into the atmosphere. Mercury in water and soil is due mostly to input from sedimentary rocks. Mercury in lake sediments is related mainly to input by country rock and anthropogenic activities such as agriculture. The mercury content of coal is similar to or less than the amount found in the earths crust. Natural charcoal is also able to capture mercury at low temperature combustion. The amount of mercury emitted from the stack of coal-fired power plants is related to the nature of the milled coal and its mineralogical and elemental content. Mercury emissions originating from the combustion of coal from electric utility power plants are considered to be among the greatest contributors to global mercury air emissions. In order to quantify the impact the electric power industry has on the environment, information regarding mercury concentrations in coal and their speciation is needed. For this reason the author examined the behaviour of mercury in three coal samples ashed at increasing temperatures. Mercury removal from coal-fired power plants ranges from 10 to 50 per cent by fabric filters and 20 to 95 per cent by FGD systems. This data will help in regulating emissions of hazardous air pollutants from electric utility steam generating units and will potentially provide insight into the industry's contribution to the global mercury burden. 50 refs

  3. Mercury biogeochemistry: Paradigm shifts, outstanding issues and research needs

    Science.gov (United States)

    Sonke, Jeroen E.; Heimbürger, Lars-Eric; Dommergue, Aurélien

    2013-05-01

    Half a century of mercury research has provided scientists and policy makers with a detailed understanding of mercury toxicology, biogeochemical cycling and past and future impacts on human exposure. The complexity of the global biogeochemical mercury cycle has led to repeated and ongoing paradigm shifts in numerous mercury-related disciplines and outstanding questions remain. In this review, we highlight some of the paradigm shifts and questions on mercury toxicity, the risks and benefits of seafood consumption, the source of mercury in seafood, and the Arctic mercury cycle. We see a continued need for research on mercury toxicology and epidemiology, for marine mercury dynamics and ecology, and for a closer collaboration between observational mercury science and mercury modeling in general. As anthropogenic mercury emissions are closely tied to the energy cycle (in particular coal combustion), mercury exposure to humans and wildlife are likely to persist unless drastic emission reductions are put in place.

  4. Crystal growth of fluoridated hydroxyapatites inhibited in the presence of gelatin.

    Science.gov (United States)

    Okazaki, M; Takahashi, J; Kumura, H

    1989-12-01

    Three types of fluoridated hydroxyapatites were synthesized in the presence of low concentrations of gelatin solution. The crystallinity of gelatin-free fluoridated hydroxyapatites increased at high degree of fluoridation, after it showed complex behavior at lower fluoride content. However, increasing of gelatin concentration in the solution, the crystallinity decreased, especially at high fluoride content. Chemical analysis and a- and c-axis dimensions showed no significant difference among those series, and gelatin contents in the precipitates were negligible when compared with the supplied amounts. These results suggest that gelatin may inhibit the crystal growth of fluoridated apatites only as a surrounding factor, overcoming the promoting action of fluoride.

  5. Mercury erosion experiments for spallation target system

    International Nuclear Information System (INIS)

    Kinoshita, Hidetaka; Kaminaga, Masanori; Haga, Katsuhiro; Hino, Ryutaro

    2003-01-01

    The Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a plan to construct the spallation neutron source at the Tokai Research Establishment, JAERI, under the High-Intensity Proton Accelerator Project (J-PARC). A mercury circulation system has been designed so as to supply mercury to the target stably under the rated flow rate of 41 m 3 /hr. Then, it was necessary to confirm a mercury pump performance from the viewpoint of making the mercury circulation system feasible, and more, to investigate erosion rate under the mercury flow as well as an amount of mercury remained on the surface after drain from the viewpoints of mechanical strength relating to the lifetime and remote handling of mercury components. The mercury pump performance was tested under the mercury flow conditions by using an experimental gear pump, which had almost the same structure as a practical mercury pump to be expected in the mercury circulation system, and the erosion rates in a mercury pipeline as well as the amount of mercury remained on the surface were also investigated. The discharged flow rates of the experimental gear pump increased linearly with the rotation speed, so that the gear pump would work as the flow meter. Erosion rates obtained under the mercury velocity less than 1.6 m/s was found to be so small that decrease of pipeline wall thickness would be 390 μm after 30-year operation under the rated mercury velocity of 0.7 m/s. For the amount of remaining mercury on the pipeline, remaining rates of weight and volume were estimated at 50.7 g/m 2 and 3.74 Hg-cm 3 /m 2 , respectively. Applying these remaining rates of weight and volume to the mercury target, the remaining mercury was estimated at about 106.5 g and 7.9 cm 3 . Radioactivity of this remaining mercury volume was found to be three-order lower than that of the target casing. (author)

  6. 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.

  7. Solubility and fluoride release in ionomers and compomers.

    Science.gov (United States)

    Bertacchini, S M; Abate, P F; Blank, A; Baglieto, M F; Macchi, R L

    1999-03-01

    The degree of solubility and the fluoride release of glass-ionomer cements and "compomers" were determined as a function of time. Three conventional glass-ionomer cements, three hybrid ionomers, and two compomers were included in the study. Disk-shaped specimens were prepared and immersed in a lactic acid solution. Solubility was evaluated from determinations of loss of mass as a function of time. To evaluate fluoride release, similar specimens were immersed in 50 mL of deionized water to which 50 mL of buffer solution was added. A fluoride ion detector was used to read the concentration of fluoride ion in the overall solution at different times after immersion. Material and time factors had a significant influence on results. The compomers showed less corrosion and fluoride release than the ionomers. Some correlation was found between solubility and fluoride leakage values. Components of both the ionomers and compomers that were studied can dissolve in water. The materials leak fluoride ions in amounts that differ according to the characteristics of the individual products.

  8. Statistical modeling of global geogenic fluoride contamination in groundwaters.

    Science.gov (United States)

    Amini, Manouchehr; Mueller, Kim; Abbaspour, Karim C; Rosenberg, Thomas; Afyuni, Majid; Møller, Klaus N; Sarr, Mamadou; Johnson, C Annette

    2008-05-15

    The use of groundwater with high fluoride concentrations poses a health threat to millions of people around the world. This study aims at providing a global overview of potentially fluoride-rich groundwaters by modeling fluoride concentration. A large database of worldwide fluoride concentrations as well as available information on related environmental factors such as soil properties, geological settings, and climatic and topographical information on a global scale have all been used in the model. The modeling approach combines geochemical knowledge with statistical methods to devise a rule-based statistical procedure, which divides the world into 8 different "process regions". For each region a separate predictive model was constructed. The end result is a global probability map of fluoride concentration in the groundwater. Comparisons of the modeled and measured data indicate that 60-70% of the fluoride variation could be explained by the models in six process regions, while in two process regions only 30% of the variation in the measured data was explained. Furthermore, the global probability map corresponded well with fluorotic areas described in the international literature. Although the probability map should not replace fluoride testing, it can give a first indication of possible contamination and thus may support the planning process of new drinking water projects.

  9. Protection From Dental Erosion: All Fluorides are Not Equal.

    Science.gov (United States)

    Faller, Robert V; Noble, Warden H

    2018-03-01

    All fluoride sources help strengthen teeth against bacterial acids that cause caries. However, excessive exposure to dietary acids, which can result in dental erosion, presents a more aggressive level of challenge compared to caries. Despite the fact that almost all toothpastes contain fluoride, both the incidence and prevalence of dental erosion appear to be on the rise. This article: (1) describes key differences between caries and dental erosion and the ability of different fluoride sources to help prevent erosion; (2) discusses the importance of the evaluation of patients for dental erosion at the earliest stages using the Basic Erosive Wear Examination scoring system to help assess and educate patients; and (3) provides evidence-based information for making specific recommendations to patients with dental erosion. The objective of this article is to assess the comparative ability of fluoride agents to protect against dental erosion. Though all fluorides are able to help strengthen teeth against cariogenic acids, not all available sources of fluoride provide the same level of erosion protection. Daily use of a stabilized stannous fluoride dentifrice has been shown to provide the most effective means of protecting teeth against the increasing risk of dental erosion and erosive tooth wear.

  10. Fluoride intake of children: considerations for dental caries and dental fluorosis.

    Science.gov (United States)

    Buzalaf, Marília Afonso Rabelo; Levy, Steven Marc

    2011-01-01

    Caries incidence and prevalence have decreased significantly over the last few decades due to the widespread use of fluoride. However, an increase in the prevalence of dental fluorosis has been reported simultaneously in both fluoridated and non-fluoridated communities. Dental fluorosis occurs due to excessive fluoride intake during the critical period of tooth development. For the permanent maxillary central incisors, the window of maximum susceptibility to the occurrence of fluorosis is the first 3 years of life. Thus, during this time, a close monitoring of fluoride intake must be accomplished in order to avoid dental fluorosis. This review describes the main sources of fluoride intake that have been identified: fluoridated drinking water, fluoride toothpaste, dietary fluoride supplements and infant formulas. Recommendations on how to avoid excessive fluoride intake from these sources are also given. Copyright © 2011 S. Karger AG, Basel.

  11. Touchstones and mercury at Hedeby

    Czech Academy of Sciences Publication Activity Database

    Ježek, Martin; Holub, M.

    2014-01-01

    Roč. 89, č. 1 (2014), s. 193-204 ISSN 0079-4848 Institutional support: RVO:67985912 Keywords : Hedeby * Viking Age * grave goods * touchstone * precious metal * mercury * chemical microanalysis * archaeometallurgy Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 0.278, year: 2014

  12. PERCEPTION OF MERCURY RISK INFORMATION

    Science.gov (United States)

    Approximately 8% of American women have blood Mercury levels exceeding the EPA reference dose (a dose below which symptoms would be unlikely). The children of these women are at risk of neurological deficits (lower IQ scores) primarily because of the mother's consumption of conta...

  13. A downstream voyage with mercury

    Science.gov (United States)

    Heinz, Gary

    2016-01-01

    Retrospective essay for the Bulletin of Environmental Contamination and Toxicology.As I look back on my paper, “Effects of Low Dietary Levels of Methyl Mercury on Mallard Reproduction,” published in 1974 in the Bulletin of Environmental Contamination and Toxicology, a thought sticks in my mind. I realize just how much my mercury research was not unlike a leaf in a stream, carried this way and that, sometimes stalled in an eddy, restarted, and carried downstream at a pace and path that was not completely under my control. I was hired in 1969 by the Patuxent Wildlife Research Center to study the effects of environmental pollutants on the behavior of wildlife. A colleague was conducting a study on the reproductive effects of methylmercury on mallards (Anas platyrhynchos), and he offered to give me some of the ducklings. I conducted a pilot study, testing how readily ducklings approached a tape-recorded maternal call. Sample sizes were small, but the results suggested that ducklings from mercury-treated parents behaved differently than controls. That’s how I got into mercury research—pretty much by chance.

  14. Venus and Mercury as Planets

    Science.gov (United States)

    1974-01-01

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described.

  15. Venus and Mercury as planets

    International Nuclear Information System (INIS)

    1974-01-01

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described

  16. 76 FR 75446 - Amendment of Class E Airspace; Mercury, NV

    Science.gov (United States)

    2011-12-02

    ...-0894; Airspace Docket No. 11-AWP-14] Amendment of Class E Airspace; Mercury, NV AGENCY: Federal... Mercury, Desert Rock Airport, Mercury, NV. Decommissioning of the Mercury Non-Directional Beacon (NDB) at Mercury, Desert Rock Airport has made this action necessary for the safety and management of Instrument...

  17. Water fluoridation and the quality of information available online.

    Science.gov (United States)

    Frangos, Zachary; Steffens, Maryke; Leask, Julie

    2018-02-13

    The Internet has transformed the way in which people approach their health care, with online resources becoming a primary source of health information. Little work has assessed the quality of online information regarding community water fluoridation. This study sought to assess the information available to individuals searching online for information, with emphasis on the credibility and quality of websites. We identified the top 10 web pages returned from different search engines, using common fluoridation search terms (identified in Google Trends). Web pages were scored using a credibility, quality and health literacy tool based on Global Advisory Committee on Vaccine Safety (GAVCS) and Center for Disease Control and Prevention (CDC) criteria. Scores were compared according to their fluoridation stance and domain type, then ranked by quality. The functionality of the scoring tool was analysed via a Bland-Altman plot of inter-rater reliability. Five-hundred web pages were returned, of which 55 were scored following removal of duplicates and irrelevant pages. Of these, 28 (51%) were pro-fluoridation, 16 (29%) were neutral and 11 (20%) were anti-fluoridation. Pro, neutral and anti-fluoridation pages scored well against health literacy standards (0.91, 0.90 and 0.81/1 respectively). Neutral and pro-fluoridation web pages showed strong credibility, with mean scores of 0.80 and 0.85 respectively, while anti-fluoridation scored 0.62/1. Most pages scored poorly for content quality, providing a moderate amount of superficial information. Those seeking online information regarding water fluoridation are faced with comprehensible, yet poorly referenced, superficial information. Sites were credible and user friendly; however, our results suggest that online resources need to focus on providing more transparent information with appropriate figures to consolidate the information. © 2018 FDI World Dental Federation.

  18. 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.

  19. Monitoring of fluoride in water samples using a smartphone

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 −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.

  20. 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.

  1. Metal Fluoride Complexes of Na,K-ATPase

    Science.gov (United States)

    Cornelius, Flemming; Mahmmoud, Yasser A.; Toyoshima, Chikashi

    2011-01-01

    The Na,K-ATPase belongs to the P-type ATPase family of primary active cation pumps. Metal fluorides like magnesium-, beryllium-, and aluminum fluoride act as phosphate analogues and inhibit P-type ATPases by interacting with the phosphorylation site, stabilizing conformations that are analogous to specific phosphoenzyme intermediates. Cardiotonic steroids like ouabain used in the treatment of congestive heart failure and arrhythmias specifically inhibit the Na,K-ATPase, and the detailed structure of the highly conserved binding site has recently been described by the crystal structure of the shark Na,K-ATPase in a state analogous to E2·2K+·Pi with ouabain bound with apparently low affinity (1). In the present work inhibition, and subsequent reactivation by high Na+, after treatment of shark Na,K-ATPase with various metal fluorides are characterized. Half-maximal inhibition of Na,K-ATPase activity by metal fluorides is in the micromolar range. The binding of cardiotonic steroids to the metal fluoride-stabilized enzyme forms was investigated using the fluorescent ouabain derivative 9-anthroyl ouabain and compared with binding to phosphorylated enzyme. The fastest binding was to the Be-fluoride stabilized enzyme suggesting a preformed ouabain binding cavity, in accord with results for Ca-ATPase where Be-fluoride stabilizes the E2-P ground state with an open luminal ion access pathway, which in Na,K-ATPase could be a passage for ouabain. The Be-fluoride stabilized enzyme conformation closely resembles the E2-P ground state according to proteinase K cleavage. Ouabain, but not its aglycone ouabagenin, prevented reactivation of this metal fluoride form by high Na+ demonstrating the pivotal role of the sugar moiety in closing the extracellular cation pathway. PMID:21708939

  2. Spectrophotometric determination of fluorides in water with Hach equipment

    International Nuclear Information System (INIS)

    Acosta L, E.

    1994-11-01

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

  3. 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.

  4. Sources of fluoride pollution in Kasur district, Pakistan

    International Nuclear Information System (INIS)

    Khan, I.H.; Haq, M.M.I.

    2005-01-01

    Serious bone problems were reported in certain localities in Pakistan due to contamination of drinking water by fluoride pollution. Against WHO recommended threshold limit of 0.7 mg/L, about 40 mg/L of fluoride is determined by ion chromatographic technique of HPLC. The compositions of pollutants were investigated in the present study by examination the chemical and mineralogical studies of water and soil samples. It is found that main problem in Manga Mandi area of District Kasur, was caused due to the decomposition of phosphorus containing minerals in soil under acidic conditions. The other sources of fluoride contamination in different areas of Pakistan is being investigated. (author)

  5. The Plasma Environment at Mercury

    Science.gov (United States)

    Raines, James M.; Gershman, Daniel J.; Zurbuchen, Thomas H.; Gloeckler, George; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Krimigis, Stamatios M.; Killen, Rosemary M.; Sarantos, Menalos; hide

    2011-01-01

    Mercury is the least explored terrestrial planet, and the one subjected to the highest flux of solar radiation in the heliosphere. Its highly dynamic, miniature magnetosphere contains ions from the exosphere and solar wind, and at times may allow solar wind ions to directly impact the planet's surface. Together these features create a plasma environment that shares many features with, but is nonetheless very different from, that of Earth. The first in situ measurements of plasma ions in the Mercury space environment were made only recently, by the Fast Imaging Plasma Spectrometer (FIPS) during the MESSENGER spacecraft's three flybys of the planet in 2008-2009 as the probe was en route to insertion into orbit about Mercury earlier this year. Here. we present analysis of flyby and early orbital mission data with novel techniques that address the particular challenges inherent in these measurements. First. spacecraft structures and sensor orientation limit the FIPS field of view and allow only partial sampling of velocity distribution functions. We use a software model of FIPS sampling in velocity space to explore these effects and recover bulk parameters under certain assumptions. Second, the low densities found in the Mercury magnetosphere result in a relatively low signal-to-noise ratio for many ions. To address this issue, we apply a kernel density spread function to guide removal of background counts according to a background-signature probability map. We then assign individual counts to particular ion species with a time-of-flight forward model, taking into account energy losses in the carbon foil and other physical behavior of ions within the instrument. Using these methods, we have derived bulk plasma properties and heavy ion composition and evaluated them in the context of the Mercury magnetosphere.

  6. Chemical form matters: differential accumulation of mercury following inorganic and organic mercury exposures in zebrafish larvae.

    Science.gov (United States)

    Korbas, Malgorzata; Macdonald, Tracy C; Pickering, Ingrid J; George, Graham N; Krone, Patrick H

    2012-02-17

    Mercury, one of the most toxic elements, exists in various chemical forms each with different toxicities and health implications. Some methylated mercury forms, one of which exists in fish and other seafood products, pose a potential threat, especially during embryonic and early postnatal development. Despite global concerns, little is known about the mechanisms underlying transport and toxicity of different mercury species. To investigate the impact of different mercury chemical forms on vertebrate development, we have successfully combined the zebrafish, a well-established developmental biology model system, with synchrotron-based X-ray fluorescence imaging. Our work revealed substantial differences in tissue-specific accumulation patterns of mercury in zebrafish larvae exposed to four different mercury formulations in water. Methylmercury species not only resulted in overall higher mercury burdens but also targeted different cells and tissues than their inorganic counterparts, thus revealing a significant role of speciation in cellular and molecular targeting and mercury sequestration. For methylmercury species, the highest mercury concentrations were in the eye lens epithelial cells, independent of the formulation ligand (chloride versusl-cysteine). For inorganic mercury species, in absence of l-cysteine, the olfactory epithelium and kidney accumulated the greatest amounts of mercury. However, with l-cysteine present in the treatment solution, mercuric bis-l-cysteineate species dominated the treatment, significantly decreasing uptake. Our results clearly demonstrate that the common differentiation between organic and inorganic mercury is not sufficient to determine the toxicity of various mercury species.

  7. Chemical Form Matters: Differential Accumulation of Mercury Following Inorganic and Organic Mercury Exposures in Zebrafish Larvae

    Energy Technology Data Exchange (ETDEWEB)

    Korbas, Malgorzata; MacDonald, Tracy C.; Pickering, Ingrid J.; George, Graham N.; Krone, Patrick H. (Saskatchewan)

    2013-04-08

    Mercury, one of the most toxic elements, exists in various chemical forms each with different toxicities and health implications. Some methylated mercury forms, one of which exists in fish and other seafood products, pose a potential threat, especially during embryonic and early postnatal development. Despite global concerns, little is known about the mechanisms underlying transport and toxicity of different mercury species. To investigate the impact of different mercury chemical forms on vertebrate development, we have successfully combined the zebrafish, a well-established developmental biology model system, with synchrotron-based X-ray fluorescence imaging. Our work revealed substantial differences in tissue-specific accumulation patterns of mercury in zebrafish larvae exposed to four different mercury formulations in water. Methylmercury species not only resulted in overall higher mercury burdens but also targeted different cells and tissues than their inorganic counterparts, thus revealing a significant role of speciation in cellular and molecular targeting and mercury sequestration. For methylmercury species, the highest mercury concentrations were in the eye lens epithelial cells, independent of the formulation ligand (chloride versus L-cysteine). For inorganic mercury species, in absence of L-cysteine, the olfactory epithelium and kidney accumulated the greatest amounts of mercury. However, with L-cysteine present in the treatment solution, mercuric bis-L-cysteineate species dominated the treatment, significantly decreasing uptake. Our results clearly demonstrate that the common differentiation between organic and inorganic mercury is not sufficient to determine the toxicity of various mercury species.

  8. Determination of fluoride content in toothpaste using spectrophotometry

    Directory of Open Access Journals (Sweden)

    Susanti Pudji Hastuti

    2013-09-01

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

  9. Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: arsenic, manganese, fluoride, iron, and uranium.

    Science.gov (United States)

    Bacquart, Thomas; Frisbie, Seth; Mitchell, Erika; Grigg, Laurie; Cole, Christopher; Small, Colleen; Sarkar, Bibudhendra

    2015-06-01

    In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

  10. Mercury emission from crematories in Japan

    Directory of Open Access Journals (Sweden)

    M. Takaoka

    2010-04-01

    Full Text Available Anthropogenic sources of mercury emissions have a significant impact on global pollution. Therefore, finding uncharacterised sources and assessing the emissions from these sources are important. However, limited data are available worldwide on mercury emissions from crematories. In Japan, 99.9% of dead bodies are cremated, which is the highest percentage in the world, and more than 1600 crematories are in operation. We thus focused on emissions from crematories in Japan. The number of targeted facilities was seven, and we used continuous emission monitoring to measure the mercury concentrations and investigate mercury behaviour. The total mercury concentrations in stack gases were a few μg/Nm3 (normal cubic meters. Considering the time profile of mercury and its species in cremations, the findings confirmed that the mercury in stack gas originated from dental amalgam. The amount of mercury emissions was calculated using the total concentration and gas flow rate. Furthermore, the annual amount of mercury emission from crematories in Japan was estimated by using the total number of corpses. The emission amount was considerably lower than that estimated in the United Kingdom. From statistical analyses on population demographics and measurements, future total emissions from crematories were also predicted. As a result, the amount of mercury emitted by crematories will likely increase by 2.6-fold from 2007 to 2037.

  11. Environmental Mercury and Its Toxic Effects

    Directory of Open Access Journals (Sweden)

    Kevin M. Rice

    2014-03-01

    Full Text Available Mercury exists naturally and as a man-made contaminant. The release of processed mercury can lead to a progressive increase in the amount of atmospheric mercury, which enters the atmospheric-soil-water distribution cycles where it can remain in circulation for years. Mercury poisoning is the result of exposure to mercury or mercury compounds resulting in various toxic effects depend on its chemical form and route of exposure. The major route of human exposure to methylmercury (MeHg is largely through eating contaminated fish, seafood, and wildlife which have been exposed to mercury through ingestion of contaminated lower organisms. MeHg toxicity is associated with nervous system damage in adults and impaired neurological development in infants and children. Ingested mercury may undergo bioaccumulation leading to progressive increases in body burdens. This review addresses the systemic pathophysiology of individual organ systems associated with mercury poisoning. Mercury has profound cellular, cardiovascular, hematological, pulmonary, renal, immunological, neurological, endocrine, reproductive, and embryonic toxicological effects.

  12. Fluoride Rinses, Gels and Foams: An Update of Controlled Clinical Trials.

    Science.gov (United States)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    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. 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. 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, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam, previously established in systematic reviews. The lack of clinical trials free from bias is, however, still a concern, especially for fluoride mouth rinses and fluoride foam. There is also a scientific knowledge gap on the benefit and optimal use of these fluoride supplements in combination with daily tooth brushing with fluoride toothpaste. © 2016 The Author(s) Published by S. Karger AG, Basel.

  13. Mercury emissions from municipal solid waste combustors

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    This report examines emissions of mercury (Hg) from municipal solid waste (MSW) combustion in the United States (US). It is projected that total annual nationwide MSW combustor emissions of mercury could decrease from about 97 tonnes (1989 baseline uncontrolled emissions) to less than about 4 tonnes in the year 2000. This represents approximately a 95 percent reduction in the amount of mercury emitted from combusted MSW compared to the 1989 mercury emissions baseline. The likelihood that routinely achievable mercury emissions removal efficiencies of about 80 percent or more can be assured; it is estimated that MSW combustors in the US could prove to be a comparatively minor source of mercury emissions after about 1995. This forecast assumes that diligent measures to control mercury emissions, such as via use of supplemental control technologies (e.g., carbon adsorption), are generally employed at that time. However, no present consensus was found that such emissions control measures can be implemented industry-wide in the US within this time frame. Although the availability of technology is apparently not a limiting factor, practical implementation of necessary control technology may be limited by administrative constraints and other considerations (e.g., planning, budgeting, regulatory compliance requirements, etc.). These projections assume that: (a) about 80 percent mercury emissions reduction control efficiency is achieved with air pollution control equipment likely to be employed by that time; (b) most cylinder-shaped mercury-zinc (CSMZ) batteries used in hospital applications can be prevented from being disposed into the MSW stream or are replaced with alternative batteries that do not contain mercury; and (c) either the amount of mercury used in fluorescent lamps is decreased to an industry-wide average of about 27 milligrams of mercury per lamp or extensive diversion from the MSW stream of fluorescent lamps that contain mercury is accomplished.

  14. Mercury exposure from interior latex paint.

    Science.gov (United States)

    Agocs, M M; Etzel, R A; Parrish, R G; Paschal, D C; Campagna, P R; Cohen, D S; Kilbourne, E M; Hesse, J L

    1990-10-18

    Many paint companies have used phenylmercuric acetate as a preservative to prolong the shelf life of interior latex paint. In August 1989, acrodynia, a form of mercury poisoning, occurred in a child exposed to paint fumes in a home recently painted with a brand containing 4.7 mmol of mercury per liter (at that time the Environmental Protection Agency's recommended limit was 1.5 mmol or less per liter). To determine whether the recent use of that brand of paint containing phenylmercuric acetate was associated with elevated indoor-air and urinary mercury concentrations, we studied 74 "exposed" persons living in 19 homes recently painted with the brand and 28 "unexposed" persons living in 10 homes not recently painted with paint containing mercury. The paint samples from the homes of exposed persons contained a median of 3.8 mmol of mercury per liter, and air samples from the homes had a median mercury content of 10.0 nmol per cubic meter (range, less than 0.5 to 49.9). No mercury was detected in paint or air samples from the homes of unexposed persons. The median urinary mercury concentration was higher in the exposed persons (4.7 nmol of mercury per millimole of creatinine; range, 1.4 to 66.5) than in the unexposed persons (1.1 nmol per millimole; range, 0.02 to 3.9; P less than 0.001). Urinary mercury concentrations within the range that we found in exposed persons have been associated with symptomatic mercury poisoning. We found that potentially hazardous exposure to mercury had occurred among persons whose homes were painted with a brand of paint containing mercury at concentrations approximately 2 1/2 times the Environmental Protection Agency's recommended limit.

  15. Corrosion study in molten fluoride salt

    International Nuclear Information System (INIS)

    Keny, S.J.; Kumbhar, A.G.; Rangarajan, S.; Gupta, V.K.; Maheshwari, N.K.; Vijayan, P.K.

    2013-01-01

    Corrosion behaviors of two alloys viz. Inconel 625 and Inconel 617 were tested in molten fluoride salts of lithium, sodium and potassium (FLiNaK) in the temperature range of 550-750 ℃ in a nickel lined Inconel vessel. Electrochemical polarization (Tafel plot) technique was used for this purpose. For both alloys, the corrosion rate was found to increase sharply beyond 650 ℃ . At 600 ℃ , Inconel 625 showed a decreasing trend in the corrosion rate over a period of 24 hours, probably due to changes in the surface conditions. After fifteen days, re-testing of Inconel 625 in the same melt showed an increase in the corrosion rate. Inconel 625 was found to be more corrosion resistant than Inconel 617. (author)

  16. Electrocrystallisation of tantalum in molten fluoride media

    Energy Technology Data Exchange (ETDEWEB)

    Massot, L. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques et Materiaux, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex (France)]. E-mail: massot@chimie.ups-tlse.fr; Chamelot, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques et Materiaux, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex (France); Palau, P. [Pechiney CRV-UR GP, Parc Economique Centr' Alp, BP27, 38340 Voreppe (France); Taxil, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques et Materiaux, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex (France)

    2005-09-20

    The electrochemical nucleation of tantalum in molten alkaline fluoride media is investigated using chronoamperometry in the 670-750 deg C temperature range to optimize the operating conditions for preparing tantalum coatings for anode materials. Chronoamperometric results show that the electrodeposition process involves progressive nucleation with diffusion-controlled growth of the nuclei, which was confirmed by scanning electron microscopy. The influence of the temperature and the overpotential on the nucleation site densities is considered. Once the deposit has been obtained, plotting the roughness of the tantalum coatings as a function of the current densities reveals a minimum at about 80 mA/cm{sup 2}. This minimum is considered by the authors as a consequence of the progressive nucleation.

  17. RECOVERY OF MERCURY FROM CONTAMINATED LIQUID WASTES

    Energy Technology Data Exchange (ETDEWEB)

    Robin M. Stewart

    1999-09-29

    Mercury was widely used in U.S. Department of Energy (DOE) weapons facilities, resulting in a broad range of mercury-contaminated wastes and wastewaters. Some of the mercury contamination has escaped to the local environment, particularly at the Y-12 Plant in Oak Ridge, Tennessee, where approximately 330 metric tons of mercury were discharged to the environment between 1953 and 1963 (TN & Associates, 1998). Effective removal of mercury contamination from water is a complex and difficult problem. In particular, mercury treatment of natural waters is difficult because of the low regulatory standards. For example, the Environmental Protection Agency has established a national ambient water quality standard of 12 parts-per-trillion (ppt), whereas the standard is 1.8 ppt in the Great Lakes Region. In addition, mercury in the environment is typically present in several different forms, but sorption processes are rarely effective with more than one or two of these forms. To meet the low regulatory discharge limits, an effective sorption process must be able to address all forms of mercury present in the water. One approach is to apply different sorbents in series depending on the mercury speciation and the regulatory discharge limits. ADA Technologies, Inc. has developed four new sorbents to address the variety of mercury species present in industrial discharges and natural waters. Three of these sorbents have been field tested on contaminated creek water at the Y-12 Plant. Two of these sorbents have been successfully demonstrated very high removal efficiencies for soluble mercury species, reducing mercury concentrations at the outlet of a pilot-scale system to less than 12 ppt for as long as six months. The other sorbent tested at the Y-12 Plant targeted colloidal mercury not removed by standard sorption or filtration processes. At the Y-12 Plant, colloidal mercury appears to be associated with iron, so a sorbent that removes mercury-iron complexes in the presence of a

  18. [Incidence of caries in the Canton Waadt (Vaud) after the change from fluoride tablets to fluoridization of salt].

    Science.gov (United States)

    Marthaler, T M; Crousaz, P; Meyer, R; Regolati, B; Robert, A

    1975-01-01

    This report shows results of a survey on dental caries in the Canton of Vaud in the years 1970 and 1974. In this canton fluoridation was carried out by means of fluoride tablets distributed at school until 1969/70 and in subsequent years by adding 250 mg F/kg fluoride to domestic salt. For comparison, results from adjoining and other cantons are also presented. In 1970 the 3 communities in the Canton of Vaud (Moudon, Grandson and Vevey) showed a remarkably low overall caries level due to the distribution of fluoride tablets, supplemented in Grandson with regular brushings with fluoride solution. When the fluoride tablets were discontinued in 1968/70 and fluoridated domestic salt containing 250 mg F/kg NaCl was introduced, caries incidence reached an even lower level. In these 3 communities caries prevalence fell to the lowest level reached, so far, by means of preventive measures in Bettlach (Canton of Solothurn, toothbrushing with fluoride solutions 6 times per year combined with information, fluoride tablets on every school day, and in addition consumption of table salt fluoridated at a suboptimal level of 90 ppm). The children in the control communities Romont (Canton of Fribourg), St-Aubin (Canton of Neuchâtel) and Châtel-St-Denis (Canton of Fribourg) also showed decreases of caries levels from 1970 to 1974. This decrease can be attributed to the distribution of fluoride tablets started at the schools of this community in the late sixties. Caries incidence in the age spans 8 to 12 and 10 to 14 years was estimated. Children from the Canton of Vaud where fluoridated table salt was practically the only preventive measure showed a smaller DMF increase than those from the cantons Fribourg and Neuchâtel. By means of a method combining DMF means of various age groups it was possible to obtain sufficiently large numbers of children for a study of the caries prevalence in each community. All communities showed a decrease of caries levels. In the Canton of Vaud this

  19. 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.

  20. An Epidemiological Study of Mercury Sensitization

    Directory of Open Access Journals (Sweden)

    Kazuhiro Sato

    1997-01-01

    Full Text Available Mercury sensitization has been historically in question and may be related to recent increases of type I allergic diseases. To clarify the epidemiological factors of mercury sensitization, we investigated factors relating to mercury sensitization in 215 medical students. Their allergic symptoms, family histories and lifestyles were studied by questionnaire. Patch tests were performed with HgCI2 (0.05% aq. and NiS04 (5% aq.. Anti- Dermatophagoides and anti-Crypfomeria pollen IgE antibodies in sera were also measured. Urinary mercury concentrations were measured in 25 mercury sensitized and 44 non-sensitized subjects (controls. Hair mercury concentrations were also measured in 19 sensitized and 22 non-sensitized subjects. While the positive rate of nickel was 6.0% (13/215, that of mercury was high (13.0%; 28/215. The subjects' individual histories of allergic rhinitis, eczema, urticaria and allergic conjunctivitis were significantly associated with family histories of these conditions (P<0.01, P<0.005 and P<0.005, respectively, as reported in the literature. However, no allergen- specific antibody positivity or past history of allergic disease was associated with mercury sensitization. Mercury sensitized subjects had experienced eczema caused by cosmetics, shampoos, soaps and haircreams significantly more frequently (P<0.05. The history of mercurochrome usage was not associated with mercury sensitization. The number of teeth treated with metals in mercury sensitized subjects was significantly higher than that in the control group (6.8±4.3 vs 4.8±1; P<0.05. There were significant differences in urinary mercury concentrations (specific gravity adjusted levels between mercury sensitized subjects and non-sensitized subjects (2.0±0.9 and 1.3±0.6 (xg/L, respectively; P<0.001. There were also significant differences in hair mercury concentrations between mercury sensitized and non-sensitized subjects (2.0±0.9 and 1.2±0.5 μg/g, respectively; P<0

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

    Science.gov (United States)

    Wong, May Cm; Glenny, Anne-Marie; Tsang, Boyd Wk; Lo, Edward Cm; Worthington, Helen V; Marinho, Valeria Cc

    2010-01-20

    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. To describe the relationship between the use of topical fluorides in young children and the risk of developing dental fluorosis. Electronic search of the Cochrane Oral Health Group Trials Register, CENTRAL, MEDLINE, EMBASE, BIOSIS, Dissertation Abstracts and LILACS/BBO. Reference lists from relevant articles were searched. Date of the most recent searches: 9th March 09. Randomised controlled trials (RCTs), quasi-RCTs, cohort studies, case-control studies and cross-sectional surveys, in which fluoride toothpastes, mouthrinses, gels, foams, paint-on solutions, and varnishes were compared to an alternative fluoride treatment, placebo or no intervention group. Children under the age of 6 years at the time topical fluorides were used. Data from all included studies were extracted by two review authors. Risk ratios for controlled, prospective studies and odds ratios for case-control studies or cross-sectional surveys were extracted or calculated. Where both adjusted and unadjusted risk ratios or odds ratios were presented, the adjusted value was included in the meta-analysis. 25 studies were included: 2 RCTs, 1 cohort study, 6 case-control studies and 16 cross-sectional surveys. Only one RCT was judged to be at low risk of bias. The other RCT and all observational studies were judged to be at moderate to high risk of bias. Studies were included in four intervention/exposure comparisons. A statistically significant reduction in fluorosis was found if brushing of a child's teeth with fluoride toothpaste commenced after the age of 12 months odds ratio 0.70 (random-effects: 95% confidence interval 0.57 to 0.88) (data from observational studies). Inconsistent statistically significant

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

    DEFF Research Database (Denmark)

    Anderson, Maria; Grindefjord, Margaret; Dahllöf, Göran

    2016-01-01

    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...... 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......-annual fluoride varnish applications did not seem to significantly influence the oral microflora in preschool children. TRIAL REGISTRATION: www.controlled-trials.com (ISRCTN35086887) 20131216 'retrospectively registered'....

  3. Water fluoridation for the prevention of dental caries.

    Science.gov (United States)

    Iheozor-Ejiofor, Zipporah; Worthington, Helen V; Walsh, Tanya; O'Malley, Lucy; Clarkson, Jan E; Macey, Richard; Alam, Rahul; Tugwell, Peter; Welch, Vivian; Glenny, Anne-Marie

    2015-06-18

    Dental caries is a major public health problem in most industrialised countries, affecting 60% to 90% of school children. Community water fluoridation was initiated in the USA in 1945 and is currently practised in about 25 countries around the world; health authorities consider it to be a key strategy for preventing dental caries. Given the continued interest in this topic from health professionals, policy makers and the public, it is important to update and maintain a systematic review that reflects contemporary evidence. To evaluate the effects of water fluoridation (artificial or natural) on the prevention of dental caries.To evaluate the effects of water fluoridation (artificial or natural) on dental fluorosis. We searched the following electronic databases: The Cochrane Oral Health Group's Trials Register (to 19 February 2015); The Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2015); MEDLINE via OVID (1946 to 19 February 2015); EMBASE via OVID (1980 to 19 February 2015); Proquest (to 19 February 2015); Web of Science Conference Proceedings (1990 to 19 February 2015); ZETOC Conference Proceedings (1993 to 19 February 2015). We searched the US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization's WHO International Clinical Trials Registry Platform for ongoing trials. There were no restrictions on language of publication or publication status in the searches of the electronic databases. For caries data, we included only prospective studies with a concurrent control that compared at least two populations - one receiving fluoridated water and the other non-fluoridated water - with outcome(s) evaluated at at least two points in time. For the assessment of fluorosis, we included any type of study design, with concurrent control, that compared populations exposed to different water fluoride concentrations. We included populations of all ages that received fluoridated water (naturally or artificially

  4. Ratiometric fluorescence signalling of fluoride ions by an ...

    Indian Academy of Sciences (India)

    Keywords. Chemosensor; ratiometric fluorescence signalling; fluoride ion; proton transfer; density functional calculation. ... Ravi Kumar Kanaparthi1 Anunay Samanta1. School of Chemistry, University of Hyderabad, Hyderabad 500 046; Training School, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 ...

  5. Readying Community Water Fluoridation Advocates through Training, Surveillance, and Empowerment.

    Science.gov (United States)

    Veschusio, C; Jones, M K; Mercer, J; Martin, A B

    2017-11-10

    This paper describes the Community Water Fluoridation Advocacy Training Project that was designed to develop networks of community water fluoridation advocates in rural communities. The South Carolina (SC) Department of Health and Environmental Control Division of Oral Health staff and the SC Dental Association were responsible for developing and facilitating the training sessions for key policy influencers, which included medical and dental providers, early childhood educators, and water system operators and managers. Findings from the post-training survey indicate that participants increased their knowledge and skills to discuss the impact of water fluoridation on the dental health of community residents. Participants identified a need for online access to water fluoridation education and advocacy materials. Dental public health competencies illustrated: communication and collaboration with groups and individuals, and advocate, implement and evaluate public health policy, legislation and regulations. Copyright© 2017 Dennis Barber Ltd.

  6. [Pharmacokinetic study of various fluoride compounds in rats].

    Science.gov (United States)

    Solymosi, G; Kertész, P; Ritlop, B; Bánóczy, J

    1992-02-01

    The fluoride excretion of 40 rats has been monitored after the consumption of drinking water containing NaF, CaF2 and CaF2 + alum (KRl/SO4/2. The fluoride excretion of the animals containing NaF and CaF2 + alum increased in a significant extent. No significant difference could be found in the fluoride excretion of the two groups. Statistically no significant increase has been observed in the fluoride ion excretion after the consumption of CaF2. These results suggest that by systemic intake of CaF2, no CaF2 absorbtion can be observed. So those undesirable gastric mucosa side effects that can be observed or presumed by the intake of NaF and CaF2 + alum are presumably neglibile.

  7. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing

    Indian Academy of Sciences (India)

    withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  8. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing ...

    Indian Academy of Sciences (India)

    withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  9. 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.

  10. Chemical Emergency Preparedness and Prevention Advisory: Hydrogen Fluoride

    Science.gov (United States)

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

  11. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Science.gov (United States)

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

    2010-01-01

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

  12. Latest developments in non-fluoridated remineralizing technologies.

    Science.gov (United States)

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

    2012-01-01

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

  13. Theoretical study of H center in lithium fluoride

    International Nuclear Information System (INIS)

    Muniz, R.B.

    1977-03-01

    A phenomenological model for the electronic description of the H center in lithium fluoride is presented. Problems concerning the calculation of the hyperfine dipolar constants are also discussed, as well as ways to overcome them. (Author) [pt

  14. Preparation of rare earth fluorides from apatite concentrate

    International Nuclear Information System (INIS)

    Mulyarchuk, I.F.; Voloshchenko, M.V.; Zen'kovich, E.G.; Sumenkova, V.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Lit'ya)

    1980-01-01

    The processes of preparation of the rare earths element sum from apatite concentrate of the Khibins, connected with preliminary extraction of rare earth phosphates from nitric acid extract using solvent extraction or direct precipitation from the extract by solution of potassium and ammonium fluorides. The sequence of the processes of the first variant is the following: solvent extraction of rare earths by tributylphosphate from clarified nitric acid extract of apatite with subsequent reextraction of rare earths with water and precipitation of rare earth phosphates from aqueous solution during neutralization by ammonia. In case of fluoride preparation from rare earth phosphate the main attention is paid to precipitation and filtration of fluorides. Technological scheme and cost price of industry for the production of 1800 t of rare earth trifluorides a year are calculated. When taking account of TBP losses according to its solubility the industry cost price is 1O times lower the modern cost of rare earth fluorides

  15. Mercury Phase II Study - Mercury Behavior across the High-Level Waste Evaporator System

    Energy Technology Data Exchange (ETDEWEB)

    Bannochie, C. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Crawford, C. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Jackson, D. G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Shah, H. B. [Savannah River Remediation, LLC., Aiken, SC (United States); Jain, V. [Savannah River Remediation, LLC., Aiken, SC (United States); Occhipinti, J. E. [Savannah River Remediation, LLC., Aiken, SC (United States); Wilmarth, W. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-06-17

    The Mercury Program team’s effort continues to develop more fundamental information concerning mercury behavior across the liquid waste facilities and unit operations. Previously, the team examined the mercury chemistry across salt processing, including the Actinide Removal Process/Modular Caustic Side Solvent Extraction Unit (ARP/MCU), and the Defense Waste Processing Facility (DWPF) flowsheets. This report documents the data and understanding of mercury across the high level waste 2H and 3H evaporator systems.

  16. Assessing Mercury and Methylmercury Bioavailability in Sediment Pore Water Using Mercury-Specific Hydrogels

    Science.gov (United States)

    2015-06-01

    FINAL REPORT Assessing Mercury and Methylmercury Bioavailability in Sediment Pore Water Using Mercury -Specific Hydrogels SERDP Project ER-1771...From - To) 2010-2015 4. TITLE AND SUBTITLE Assessing Mercury and Methylmercury Bioavailability in 5a. CONTRACT NUMBER W912HQ-10-C-0069 Sediment...Using Mercury -Specific DGTs 5b. GRANT NUMBER ER-1771 5c. PROGRAM ELEMENT NUMBER NA 6. AUTHOR(S) Magar, Victor S.*, Steenhaut, Nicholas

  17. Mercury concentrations at a historically mercury-contaminated site in KwaZulu-Natal, South Africa

    CSIR Research Space (South Africa)

    Williams, CR

    2011-02-01

    Full Text Available . Biogeochem., 43:237?257 Barrat GJ, Combrink J (2002) An Assessment of the degree of mercury (Hg) bio-transformation in two river systems following discharges from a mercury recovery plant. Water SA Special Edition: WISA Proceedings 2002 Benoit JM... in mercury and methylmercury biogeochemical cycling and bioaccumulation within shallow estuaries. PhD thesis, University of Maryland, College Park Kim E-H, Mason RP, Porter ET, Soulen HL (2006) The impact of resuspension on sediment mercury dynamics...

  18. Amended Silicated for Mercury Control

    Energy Technology Data Exchange (ETDEWEB)

    James Butz; Thomas Broderick; Craig Turchi

    2006-12-31

    Amended Silicates{trademark}, a powdered, noncarbon mercury-control sorbent, was tested at Duke Energy's Miami Fort Station, Unit 6 during the first quarter of 2006. Unit 6 is a 175-MW boiler with a cold-side electrostatic precipitator (ESP). The plant burns run-of-the-river eastern bituminous coal with typical ash contents ranging from 8-15% and sulfur contents from 1.6-2.6% on an as-received basis. The performance of the Amended Silicates sorbent was compared with that for powdered activated carbon (PAC). The trial began with a period of baseline monitoring during which no sorbent was injected. Sampling during this and subsequent periods indicated mercury capture by the native fly ash was less than 10%. After the baseline period, Amended Silicates sorbent was injected at several different ratios, followed by a 30-day trial at a fixed injection ratio of 5-6 lb/MMACF. After this period, PAC was injected to provide a comparison. Approximately 40% mercury control was achieved for both the Amended Silicates sorbent and PAC at injection ratios of 5-6 lbs/MMACF. Higher injection ratios did not achieve significantly increased removal. Similar removal efficiencies have been reported for PAC injection trials at other plants with cold-side ESPs, most notably for plants using medium to high sulfur coal. Sorbent injection did not detrimentally impact plant operations and testing confirmed that the use of Amended Silicates sorbent does not degrade fly ash quality (unlike PAC). The cost for mercury control using either PAC or Amended Silicates sorbent was estimated to be equivalent if fly ash sales are not a consideration. However, if the plant did sell fly ash, the effective cost for mercury control could more than double if those sales were no longer possible, due to lost by-product sales and additional cost for waste disposal. Accordingly, the use of Amended Silicates sorbent could reduce the overall cost of mercury control by 50% or more versus PAC for locations where

  19. Chitosan microparticles for the controlled delivery of fluoride.

    Science.gov (United States)

    Keegan, Gemma M; Smart, John D; Ingram, Matthew J; Barnes, Lara-Marie; Burnett, Gary R; Rees, Gareth D

    2012-03-01

    To manufacture and characterise chitosan/fluoride microparticles prepared by spray drying and assess their utility as controlled release vehicles for fluoride. Microparticles were manufactured from dispersions containing 1.0% and 2.0% (w/v) chitosan and 0.20% or 0.40% (w/v) NaF in the absence/presence of glutaraldehyde. Particle size distributions were determined using laser diffraction; fluoride loading and release were determined by ion-selective electrode. Release profiles were studied in isotonic media (pH 5.5) over 360 min; microparticles exhibiting greatest cumulative fluoride release were further evaluated at pH 4.0 and 7.0. Particle morphology was investigated using environmental scanning electron microscopy. Bioadhesion parameters were determined with a texture-probe analyser. Microparticles exhibited low polydispersity and volume mean diameters (VMDs) <6 μm. VMDs increased on doubling the chitosan/fluoride concentrations but were largely independent of glutaraldehyde concentration. Recovered yields were inversely proportional to dispersion viscosity due to compromised fluid atomisation; adding NaF reduced viscosity and improved yields. Best-case entrapment efficiency and NaF loading were 84.1% and 14%, respectively. Release profiles were biphasic, releasing 40-60% of the total fluoride during the first 600 s, followed by a prolonged release phase extending out to 6h. Incorporation of 0.40% NaF to the 2.0% chitosan dispersion yielded microparticles with reduced bioadhesive parameters (F(max) and WOA) versus the chitosan-only control whilst retaining significant bioadhesive potential. Bioadhesive chitosan/fluoride microparticles manufactured using a spray-drying protocol have been extensively characterised and further opportunity for optimisation identified. These microparticles may provide a means of increasing fluoride uptake from oral care products to provide increased protection against caries, however further work is required to demonstrate this

  20. Percolation of cadmium across a mercury film

    International Nuclear Information System (INIS)

    Malek, K.; Gobal, F.

    2003-01-01

    Electrodeposition/dissolution of cadmium onto a film of mercury shows some deviations from the natural liquidity of mercury caused by the reduction of Cd onto it. Percolation and fractal analyzes were done on the surface and the bulk of the mercury film during diffusion of Cd species (atoms). These show that the fractal dimensions of the Cd-inserted mercury film are about 2.11 and 2.54 near the surface of the mercury film and at deeper points inside the film, respectively. The insertion process has a negligible effect on the surface morphology of the mercury film and there is a phase transition in the bulk, as well as a geometrical transition during the Cd-insertion (de-insertion) process. This corresponds to a percolation threshold of about 0.2 mol l -1 Cd content

  1. Mercury in dated Greenland marine sediments

    DEFF Research Database (Denmark)

    Asmund, G.; Nielsen, S.P.

    2000-01-01

    Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age...... of the sediment for the youngest 100 years. As a rule the mercury decreased with depth in the sediment with various degrees of significance. The increase of the mercury flux during the last 100 years is roughly a doubling. The increase may be of anthropogenic origin as it is restricted to the last 100 years....... In four cores the concentration of manganese was found also to increase in the top layers indicating diagenesis. In the other cases the higher concentrations were not accompanied by higher manganese concentrations. The mercury flux to the sediment surface was generally proportional to the Pb-210 flux...

  2. Human accumulation of mercury in Greenland

    DEFF Research Database (Denmark)

    Johansen, P.; Mulvad, G.; Pedersen, H. S.

    2007-01-01

    In the Arctic, the traditional diet exposes its people to a high intake of mercury especially from marine mammals. To determine whether the mercury is accumulated in humans, we analyzed autopsy samples of liver, kidney and spleen from adult ethnic Greenlanders who died between 1990 and 1994 from...... a wide range of causes, natural and violent. Liver, kidney and spleen samples from between 33 and 71 case subjects were analyzed for total mercury and methylmercury, and liver samples also for selenium. Metal levels in men and women did not differ and were not related to age except in one case, i.......e. for total mercury in liver, where a significant declining concentration with age was observed. The highest total mercury levels were found in kidney followed by liver and spleen. Methylmercury followed the same pattern, but levels were much lower, constituting only 19% of the total mercury concentration...

  3. Acclimation of subsurface microbial communities to mercury

    DEFF Research Database (Denmark)

    de Lipthay, Julia R; Rasmussen, Lasse D; Øregaard, Gunnar

    2008-01-01

    We studied the acclimation to mercury of bacterial communities of different depths from contaminated and noncontaminated floodplain soils. The level of mercury tolerance of the bacterial communities from the contaminated site was higher than those of the reference site. Furthermore, the level...... of mercury tolerance and functional versatility of bacterial communities in contaminated soils initially were higher for surface soil, compared with the deeper soils. However, following new mercury exposure, no differences between bacterial communities were observed, which indicates a high adaptive potential...... of the subsurface communities, possibly due to differences in the availability of mercury. IncP-1 trfA genes were detected in extracted community DNA from all soil depths of the contaminated site, and this finding was correlated to the isolation of four different mercury-resistance plasmids, all belonging...

  4. SITUATION OF FLUORIDES RATE IN WATERS AND MAJOR ...

    African Journals Online (AJOL)

    31 déc. 2010 ... by fluoride ions in the waters of the region (Fluorosis Dental and skeletal). This study proposes, the estimated daily intake of fluoride from its water .... Le fluor est dosé par la méthode potentiométrique (NF T 90-004) grâce à une électrode spécifique aux ions fluorures. La mesure du potentiel a été effectuée ...

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

    Directory of Open Access Journals (Sweden)

    Devyatkin S.V.

    2003-01-01

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

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

    OpenAIRE

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

    2011-01-01

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

  7. Estimation of Toothpaste Fluoride Intake in Preschool Children

    OpenAIRE

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

    2013-01-01

    The objective of this study was to estimate the intake of toothpaste fluoride used by children aged 2 to 6 years (n=87) treated at a hospital of a medium-sized city (Campina Grande, PB) in the Northeastern region of Brazil. Data regarding sociodemographic characteristics of families and children's toothbrushing were collected from questionnaire-based interviews with parents/guardians, and the amount of fluoride used during toothbrushing was estimated using a precision scale for assessment of ...

  8. 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.

  9. Quality of our groundwater resources: Arsenic and fluoride

    Science.gov (United States)

    Nordstrom, D. Kirk

    2011-01-01

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

  10. Fluoride concentration in dentine as a biomarker of fluoride intake in European roe deer (Capreolus capreolus) - an electron-microprobe study.

    Science.gov (United States)

    Richter, Heiko; Kierdorf, Uwe; Richards, Alan; Melcher, Frank; Kierdorf, Horst

    2011-08-01

    Fluoride concentration in dentine has been recommended as the best marker for the level of chronic fluoride intake and the most suitable indicator of an individual's total body burden of fluoride. We analysed fluoride concentrations in the dentine of cheek teeth of European roe deer from fluoride-polluted habitats to retrospectively assess the level of fluoride uptake into the tissue. Thereby, we tested the hypothesis of the existence of mechanisms that limit fluoride intake of individuals and fluoride exposure of forming dental hard tissues during the late foetal and early postnatal periods in the species. Using electron-microprobe analysis, fluoride profiles were obtained on sectioned P(4)s, M(1)s, and M(3)s from individuals exhibiting pronounced dental fluorosis. Fluoride concentrations were compared between early formed (peripheral) and late-formed (juxtapulpal) dentine both within single teeth and amongst the three different teeth studied. Peripheral dentine of the M(1), which is formed during the late foetal and early postnatal periods, exhibited markedly lower fluoride concentrations than juxtapulpal dentine of the same tooth and both, peripheral and juxtapulpal dentine of P(4) and M(3) that are formed post-weaning. Our study provides strong support for the hypothesis that in the European roe deer the prenatal and early postnatal (pre-weaning) stages of dental development are (largely) protected against exposure to excess fluoride. This is attributed to the operation of certain protective mechanisms during these periods. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Thiosulphate assisted phytoextraction of mercury contaminated soils at the Wanshan Mercury Mining District, Southwest China

    Directory of Open Access Journals (Sweden)

    J. Wang

    2013-10-01

    Full Text Available Wanshan, known as the “Mercury Capital” of China, is located in the Southwest of China. Due to the extensive mining and smelting works in the Wanshan area, the local ecosystem has been serious contaminated with mercury. In the present study, a number of soil samples were taken from the Wanshan mercury mining area and the mercury fractionations in soils were analyzed using sequential extraction procedure technique. The obtained results showed that the dominate mercury fractions (represent 95% of total mercury were residual and organic bound mercury. A field trial was conducted in a mercury polluted farmland at the Wanshan mercury mine. Four plant species Brassica juncea Czern. et Coss.var. ASKYC (ASKYC, Brassica juncea Czern. et Coss.var.DPDH (DPDH, Brassica juncea Czern. et Coss.var.CHBD(CHBD, Brassica juncea Czern. et Coss.var.LDZY (LDZY were tested their ability to extract mercury from soil with thiosulphate amendment. The results indicated that the mercury concentration in the roots and shoots of the four plants were significantly increased with thiosulphate treatment. The mercury phytoextraction yield of ASKYC, DPDH, CHBD and LDZY were 92, 526, 294 and 129 g/ha, respectively

  12. Blood Mercury Levels of Zebra Finches Are Heritable: Implications for the Evolution of Mercury Resistance.

    Directory of Open Access Journals (Sweden)

    Kenton A Buck

    Full Text Available Mercury is a ubiquitous metal contaminant that negatively impacts reproduction of wildlife and has many other sub-lethal effects. Songbirds are sensitive bioindicators of mercury toxicity and may suffer population declines as a result of mercury pollution. Current predictions of mercury accumulation and biomagnification often overlook possible genetic variation in mercury uptake and elimination within species and the potential for evolution in affected populations. We conducted a study of dietary mercury exposure in a model songbird species, maintaining a breeding population of zebra finches (Taeniopygia guttata on standardized diets ranging from 0.0-2.4 μg/g methylmercury. We applied a quantitative genetics approach to examine patterns of variation and heritability of mercury accumulation within dietary treatments using a method of mixed effects modeling known as the 'animal model'. Significant variation in blood mercury accumulation existed within each treatment for birds exposed at the same dietary level; moreover, this variation was highly repeatable for individuals. We observed substantial genetic variation in blood mercury accumulation for birds exposed at intermediate dietary concentrations. Taken together, this is evidence that genetic variation for factors affecting blood mercury accumulation could be acted on by selection. If similar heritability for mercury accumulation exists in wild populations, selection could result in genetic differentiation for populations in contaminated locations, with possible consequences for mercury biomagnification in food webs.

  13. Radioactive mercury distribution in biological fluids and excretion in human subjects after inhalation of mercury vapor

    International Nuclear Information System (INIS)

    Cherian, M.G.; Hursh, J.B.; Clarkson, T.W.; Allen, J.

    1978-01-01

    The distribution of mercury in red blood cells (RBCs) and plasma, and its excretion in urine and feces are described in five human subjects during the first 7 days following inhalation of radioactive mercury vapor. A major portion (98%) of radioactive mercury in whole blood is initially accumulated in the RBCs and is transferred partly to the plasma compartment until the ratio of mercury in RBCs to plasma is about 2 within 20 h. The cumulative urinary and fecal excretion of mercury for 7 days is about 11.6% of the retained dose, and is closely related to the percent decline in body burden of mercury. There is little correlation between either the urinary excretion and plasma radioactivity of mercury, or the specific activities of urine and plasma mercury, suggesting a mechanism other than a direct glomerular filtration involved in the urinary excretion of recently exposed mercury. These studies suggest that blood mercury levels can be used as an index of recent exposure, while urinary levels may be an index of renal concentration of mercury. However, there is no reliable index for mercury concentration in the brain

  14. Thiosulphate assisted phytoextraction of mercury contaminated soils at the Wanshan Mercury Mining District, Southwest China

    Directory of Open Access Journals (Sweden)

    J Wang

    2013-10-01

    Full Text Available Wanshan, known as the “Mercury Capital” of China, is located in the Southwest of China. Due to the extensive mining and smelting works in the Wanshan area, the local ecosystem has been serious contaminated with mercury. In the present study, a number of soil samples were taken from the Wanshan mercury mining area and the mercury fractionations in soils were analyzed using sequential extraction procedure technique. The obtained results showed that the dominate mercury fractions (represent 95% of total mercury were residual and organic bound mercury. A field trial was conducted in a mercury polluted farmland at the Wanshan mercury mine. Four plant species Brassica juncea Czern. et Coss.var. ASKYC (ASKYC, Brassica juncea Czern. et Coss.var.DPDH (DPDH, Brassica juncea Czern. et Coss.var.CHBD(CHBD, Brassica juncea Czern. et Coss.var.LDZY (LDZY were tested their ability to extract mercury from soil with thiosulphate amendment. The results indicated that the mercury concentration in the roots and shoots of the four plants were significantly increased with thiosulphate treatment. The mercury phytoextraction yield of ASKYC, DPDH, CHBD and LDZY were 92, 526, 294 and 129 g/ha, respectively.

  15. STRESS SENSITIVITY OF MERCURY INJECTION MEASUREMENTS

    OpenAIRE

    Guise, P; Grattoni, C; Allshorn, S; Fisher, QJ; Schiffer, A

    2017-01-01

    Many petrophysical properties (e.g. permeability, electrical resistivity etc.) of tight rocks are very stress sensitive. However, most mercury injection measurements are made using an instrument that does not apply a confining pressure to the samples. Here we further explore the implications of the use and analysis of data from mercury injection porosimetry or mercury capillary pressure measurements (MICP). Two particular aspects will be discussed. First, the effective stress acting on sample...

  16. Mercury in polar bears from Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Lentfer, J.W.; Galster, W.A.

    1987-04-01

    Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

  17. Process for removing mercury from aqueous solutions

    Science.gov (United States)

    Googin, John M.; Napier, John M.; Makarewicz, Mark A.; Meredith, Paul F.

    1986-01-01

    A process for removing mercury from water to a level not greater than two parts per billion wherein an anion exchange material that is insoluble in water is contacted first with a sulfide containing compound and second with a compound containing a bivalent metal ion forming an insoluble metal sulfide. To this treated exchange material is contacted water containing mercury. The water containing not more than two parts per billion of mercury is separated from the exchange material.

  18. Surface composition of Mercury from reflectance spectrophotometry

    Science.gov (United States)

    Vilas, Faith

    1988-01-01

    The controversies surrounding the existing spectra of Mercury are discussed together with the various implications for interpretations of Mercury's surface composition. Special attention is given to the basic procedure used for reducing reflectance spectrophotometry data, the factors that must be accounted for in the reduction of these data, and the methodology for defining the portion of the surface contributing the greatest amount of light to an individual spectrum. The application of these methodologies to Mercury's spectra is presented.

  19. 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.

  20. 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

    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. 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. 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. 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.

  1. 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

    2017-07-01

    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.

  2. Does fluoride in drinking water delay tooth eruption?

    Science.gov (United States)

    Jolaoso, Ismail Adeyemi; Kumar, Jayanth; Moss, Mark E

    2014-01-01

    The objectives of this study are to determine the effect of fluoride exposure on permanent tooth eruption patterns as well as to understand its effect on caries attack rate by accounting for the number of erupted tooth surfaces. We analyzed data from the 1986-1987 National Survey of Oral Health of US Schoolchildren to determine the mean number of erupted permanent teeth and permanent first molars according to fluoride level in drinking water. The analysis included 13,348 children aged 5-17 years with a history of single residence. We also estimated the attack rate (decayed, missing, and filled surfaces/surfaces at risk) for fluoride deficient, suboptimal, and optimally fluoridated areas adjusting for covariates. Multivariable statistical analyses were performed to control for potential confounders. By age 7, almost all permanent first molars had erupted. The adjusted mean number of erupted permanent first molars per child were 3.81, 3.67, and 3.92 in areas with erupted teeth. Exposure to fluoride in drinking water did not delay the eruption of permanent teeth. The observed difference in dental caries experience among children exposed to different fluoride levels could not be explained by the timing of eruption of permanent teeth. © 2014 American Association of Public Health Dentistry.

  3. Fluoride varnishes containing sodium trimetaphosphate reduce enamel demineralization in vitro.

    Science.gov (United States)

    Manarelli, Michele M; Delbem, Alberto C B; Báez-Quintero, Liliana Carolina; de Moraes, Felipe Ricardo N; Cunha, Robson F; Pessan, Juliano P

    2017-07-01

    This study evaluated the effects of fluoride varnishes containing sodium trimetaphosphate (TMP) on bovine enamel demineralization in vitro. Enamel bovine discs were randomly assigned into six groups (n = 20/group): placebo, 2.5% NaF, 2.5% NaF/5% TMP, 5% NaF, 5% NaF/5% TMP, and a commercial formulation (Duraphat, 5% NaF). Varnishes were applied on all enamel discs and kept for 6 h. Loosely and firmly bound fluoride formed on/in enamel after treatment were analyzed in 10 discs from each group. The other 10 discs were subjected to a pH-cycling regimen for 7 days, and analyzed for surface (SH) and cross-sectional hardness (ΔKHN), as well as for loosely and firmly bound fluoride in/on enamel. Data were analyzed by analysis of variance (ANOVA) followed by Student-Newman-Keuls' test (p fluoridated varnishes containing TMP promoted significantly lower SH change and ΔKHN when compared with their counterparts without TMP. Loosely and firmly bound fluoride was significantly lower in groups treated with varnishes containing TMP. TMP and fluoride added to varnishes have a synergistic effect against enamel demineralization in vitro.

  4. Risk assessment of fluoride exposure in drinking water of Tunisia.

    Science.gov (United States)

    Guissouma, Wiem; Hakami, Othman; Al-Rajab, Abdul Jabbar; Tarhouni, Jamila

    2017-06-01

    The presence of fluoride in drinking water is known to reduce dental cavities among consumers, but an excessive intake of this anion might leads to dental and skeletal fluorosis. This study reports a complete survey of the fluoridated tap water taken from 100 water consumption points in Tunisia. The fluoride concentrations in tap water were between 0 and 2.4 mg L -1 . Risk assessment of Fluoride exposure was assessed depending on the age of consumers using a four-step method: hazard identification, toxicity reference values selection (TRVs), daily exposure assessment, and risk characterization. Our findings suggest that approximately 75% of the Tunisian population is at risk for dental decay, 25% have a potential dental fluorosis risk, and 20% might have a skeletal fluorosis risk according to the limits of fluoride in drinking water recommended by WHO. More investigations are recommended to assess the exposure risk of fluoride in other sources of drinking water such as bottled water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Effect of fluoride addition on the properties of dental alginate impression materials.

    Science.gov (United States)

    Lee, Yong-Keun; Lim, Bum-Soon; Kim, Cheol-We

    2004-03-01

    Fluoride-containing dental alginate impression materials can exert a considerable reduction in enamel solubility. The objective was to evaluate the effects of fluoride addition in the alginate impression materials on the properties and subsequent release of fluoride. Four experimental alginate impression materials were studied. Materials were mixed with distilled water (control) or 100-ppm fluoride solution. One or two percent NaF, or 1% SnF2 was added to the materials, which were mixed with distilled water. Fluoride release, flexibility, recovery from deformation, setting time, compressive strength and elastic modulus were determined in accordance with the ISO 1563 and ANSI/ADA Spec. 18. Fluoride release increased after addition of fluoride, and the released amount was 0.762-14.761 ppm. Addition of NaF or SnF2 resulted in higher fluoride release than the control group (p alginate impression material may result in effective release of fluoride without deteriorating the properties of material itself.

  6. Accumulation of mercury in selected plant species grown in soils contaminated with different mercury compounds

    International Nuclear Information System (INIS)

    Su, Yi; Han, Fengxiang; Shiyab, Safwan; Chen, Jian; Monts, David L.

    2007-01-01

    The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy (DOE) sites, where mercury contamination is a major concern. In order to cost effectively implement mercury remediation efforts, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds.. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal-accumulating plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl 2 , and Hg(NO 3 ) 2 , were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation, and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots ( 2 powder, respectively; no visual stress symptoms were observed. We also studied mercury phyto-remediation using aged soils that contained HgS, HgCl 2 , or Hg(NO 3 ) 2 . We have found that up to hundreds

  7. Structural study of chlorine tri-fluoride and bromine penta-fluoride in liquid and solid phase

    International Nuclear Information System (INIS)

    Rousson, R.

    1973-01-01

    This research thesis reports the structural study of chlorine tri-fluoride and bromine penta-fluoride between 20 C and about -265 C. After some generalities on these compounds and a presentation of the experimental technique, the author reports and discusses results obtained with these both compounds: Raman spectrum for the liquid and for the solid phase, infrared spectrum for the solid phase, calorimetric measurements. In the case of chlorine tri-fluoride, the author studies the evolution of the liquid spectrum with temperature, shows the existence of an intermediate solid phase, and compares results obtained by Raman spectroscopy and nuclear magnetic resonance. He also applies to bromine penta-fluoride an analysis of normal coordinates of a XF 5 molecule: relationship between force constants and vibration frequencies, application of Wilson method, resolution of the molecular equation, determination of normal vibration modes [fr

  8. The Messenger Mission to Mercury

    CERN Document Server

    Domingue, D. L

    2007-01-01

    NASA’s MESSENGER mission, launched on 3 August, 2004 is the seventh mission in the Discovery series. MESSENGER encounters the planet Mercury four times, culminating with an insertion into orbit on 18 March 2011. It carries a comprehensive package of geophysical, geological, geochemical, and space environment experiments to complete the complex investigations of this solar-system end member, which begun with Mariner 10. The articles in this book, written by the experts in each area of the MESSENGER mission, describe the mission, spacecraft, scientific objectives, and payload. The book is of interest to all potential users of the data returned by the MESSENGER mission, to those studying the nature of the planet Mercury, and by all those interested in the design and implementation of planetary exploration missions.

  9. Augustus as Mercury at last

    Directory of Open Access Journals (Sweden)

    Paulo Martins

    2017-07-01

    Full Text Available My purpose in this paper is to investigate and to analyse the representation of Augustus as Mercury, and what this association may suggest and mean to the Romans from both the urbs and the prouinciae, focusing the epigraphy, the numismatic, and the literature. Furthermore, I review three researches that someway work this problem: Bandinelli, Zanker and Martins. Even though the associations between divinities and rulers were very common – Augustus represented as Apollo, Jupiter or Neptune; Tiberius as Apollo; Claudius as Jupiter; or Commodus as Hercules –, the discussion on the relationship between Augustus and Mercury is very rare in recent bibliography. The latest relevant research on this subject dates back to the first half of the twentieth century. Chittenden’s work on numismatic and Grether’s article on epigraphy are both very important. Thus, new evidences must be considered, so that we can further investigate these representations in the Roman world.

  10. Mercury dosing solutions for fluorescent lamps

    Energy Technology Data Exchange (ETDEWEB)

    Corazza, A; Boffito, C [SAES Getters S.p.A., Viale Italia 77, Lainate (MI) 20020 (Italy)], E-mail: alessio_corazza@saes-group.com

    2008-07-21

    A review of the different technologies used to dose mercury in fluorescent lamps is presented. Conventional liquid mercury dosing is gradually being replaced with more reliable and environmentally friendly solutions that enable a significant reduction of the amount of mercury introduced in the lamp, so as to cope with more stringent regulations issued to minimize the environmental impact of exhausted lamps. This paper will review the most advanced novel methods to assure an accurate and fine dosing of mercury in fluorescent lamps, especially focusing on solutions based on the use of solid alloys.

  11. Sorbents for mercury removal from flue gas

    Energy Technology Data Exchange (ETDEWEB)

    Granite, Evan J.; Hargis, Richard A.; Pennline, Henry W.

    1998-01-01

    A review of the various promoters and sorbents examined for the removal of mercury from flue gas is presented. Commercial sorbent processes are described along with the chemistry of the various sorbent-mercury interactions. Novel sorbents for removing mercury from flue gas are suggested. Since activated carbons are expensive, alternate sorbents and/or improved activated carbons are needed. Because of their lower cost, sorbent development work can focus on base metal oxides and halides. Additionally, the long-term sequestration of the mercury on the sorbent needs to be addressed. Contacting methods between the flue gas and the sorbent also merit investigation.

  12. Risk assessment of mercury contaminated sites

    International Nuclear Information System (INIS)

    Hempel, M.

    1993-01-01

    At two sites, highly contaminated with mercury, risk assessment was executed. Methods were developed to determine organomercury compounds in water, air and soil. Toxicity tests demonstrated the high toxicity of organomercury compounds compared to inorganic mercury. Besides highly toxic methylmercury, ethylmercury was found in soils close to a chemical plant in Marktredwitz. In ultrafiltration-experiments mercury showed great affinity to high molecular substances in water. Lysimeter-experiments proved, that organomercury compounds are adsorbed and transformed to inorganic and elemental mercury. (orig.) [de

  13. Alkaline sorbent injection for mercury control

    Science.gov (United States)

    Madden, Deborah A.; Holmes, Michael J.

    2002-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  14. Apparatus for isotopic alteration of mercury vapor

    Science.gov (United States)

    Grossman, Mark W.; George, William A.; Marcucci, Rudolph V.

    1988-01-01

    An apparatus for enriching the isotopic Hg content of mercury is provided. The apparatus includes a reactor, a low pressure electric discharge lamp containing a fill including mercury and an inert gas. A filter is arranged concentrically around the lamp. In a preferred embodiment, constant mercury pressure is maintained in the filter by means of a water-cooled tube that depends from it, the tube having a drop of mercury disposed in it. The reactor is arranged around the filter, whereby radiation from said lamp passes through the filter and into said reactor. The lamp, the filter and the reactor are formed of a material which is transparent to ultraviolet light.

  15. Identification of elemental mercury in the subsurface

    Science.gov (United States)

    Jackson, Dennis G

    2015-01-06

    An apparatus and process is provided for detecting elemental mercury in soil. A sacrificial electrode of aluminum is inserted below ground to a desired location using direct-push/cone-penetrometer based equipment. The insertion process removes any oxides or previously found mercury from the electrode surface. Any mercury present adjacent the electrode can be detected using a voltmeter which indicates the presence or absence of mercury. Upon repositioning the electrode within the soil, a fresh surface of the aluminum electrode is created allowing additional new measurements.

  16. Coal fired flue gas mercury emission controls

    International Nuclear Information System (INIS)

    Wu, Jiang; Pan, Weiguo; Cao, Yan; Pan, Weiping

    2015-01-01

    Mercury (Hg) is one of the most toxic heavy metals, harmful to both the environment and human health. Hg is released into the atmosphere from natural and anthropogenic sources and its emission control has caused much concern. This book introduces readers to Hg pollution from natural and anthropogenic sources and systematically describes coal-fired flue gas mercury emission control in industry, especially from coal-fired power stations. Mercury emission control theory and experimental research are demonstrated, including how elemental mercury is oxidized into oxidized mercury and the effect of flue gas contents on the mercury speciation transformation process. Mercury emission control methods, such as existing APCDs (air pollution control devices) at power stations, sorbent injection, additives in coal combustion and photo-catalytic methods are introduced in detail. Lab-scale, pilot-scale and full-scale experimental studies of sorbent injection conducted by the authors are presented systematically, helping researchers and engineers to understand how this approach reduces the mercury emissions in flue gas and to apply the methods in mercury emission control at coal-fired power stations.

  17. Ocular disorders among workers exposed to mercury.

    Science.gov (United States)

    Gabal, M S; Raslan, O A

    1995-01-01

    Mercury vapor exposed workers may show ocular changes, as well as other systems affection. A sample of 84 workers in preparing mercury fulminate were examined for conjunctival corneal and lenticular manifestation of long duration exposure, together with mercury urinary output. Lens changes were found in 50% of the involved workers while keratopathy as recorded in 34.5% of them. No statistically significant association was found between the occurrence of eye lesions and levels of urinary elimination of mercury. These results suggest local absorption of this element is most probably the underlying cause of ocular affection.

  18. Increased mercury emissions from modern dental amalgams.

    Science.gov (United States)

    Bengtsson, Ulf G; Hylander, Lars D

    2017-04-01

    All types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor than the low copper amalgams used before the 1970s. High copper amalgams has been developed with focus on mechanical strength and corrosion resistance, but has been sub-optimized in other aspects, resulting in increased instability and higher emission of mercury vapor. This has not been presented to policy makers and scientists. Both low and high copper amalgams undergo a transformation process for several years after placement, resulting in a substantial reduction in mercury content, but there exist no limit for maximum allowed emission of mercury from dental amalgams. These modern high copper amalgams are nowadays totally dominating the European, US and other markets, resulting in significant emissions of mercury, not considered when judging their suitability for dental restoration.

  19. Side effects of mercury in dental amalgam

    Directory of Open Access Journals (Sweden)

    Titiek Berniyanti

    2008-03-01

    Full Text Available Dental amalgam is an alloy composed of mixture of approximately equal parts of elemental liquid mercury and an alloy powder. The popularity of amalgam arises from excellent long term performance, ease of use and low cost. Despite the popularity of dental amalgam as restorative material, there have been concerns regarding the potential adverse health and environmental effects arising from exposure to mercury in amalgam. They have long been believed to be of little significance as contributors to the overall body burden of mercury, because the elemental form of mercury is rapidly consumed in the setting reaction of the restoration. In 1997, 80% of dentist in Indonesia still using amalgam as an alternative material, and 60% of them treat the rest of unused amalgam carelessly. In recent years, the possible environmental and health impact caused by certain routines in dental practice has attracted attention among regulators. As part of point source reduction strategies, the discharge of mercury/amalgam-contaminated wastes has been regulated in a number of countries, even though it has been documented that by adopting appropriate mercury hygiene measures, the impact of amalgam use in dentistry is minimal. The purpose of this paper is to examine on studies that relate mercury levels in human to the presence of dental amalgams. It is concluded that even though mercury used in filling is hazardous, if normal occupational recommendations for proper mercury hygiene routines and source of reduction strategies are followed, no occupational health risk can be assumed.

  20. Observations of Mercury in 1988 and 1989

    International Nuclear Information System (INIS)

    Schmude, R.W. Jr.

    1990-01-01

    A visual study of the planet Mercury was carried out in May 1988 and in April and May 1989. Most of the observations were made with the 35.5-cm telescope at the Texas A ampersand M University Observatory. This report presents drawings and a map of Mercury that covers the longitude range of 195-285 deg. One important finding was that a polarizing filter combined with color filters gives a sharper view of the planet. It is also concluded that high-resolution images of Mercury's terminator, either as seen from the earth or with the Hubble Space Telescope, can provide information about Mercury's topography. 10 refs

  1. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  2. EDITORIAL: Mercury-free discharges for lighting

    Science.gov (United States)

    Haverlag, M.

    2007-07-01

    This special Cluster of articles in Journal of Physics D: Applied Physics covers the subject of mercury-free discharges that are being investigated by different light source researchers, as an alternative to existing mercury-containing lamps. The main driving force to move away from mercury-containing discharge light sources is connected to the environmentally unfriendly nature of mercury. After inhalation or direct contact, severe mercury exposure can lead to damage to human brain cells, the kidneys, the liver and the nervous system. For this reason, the use of mercury in products is becoming more and more restricted by different governmental bodies. In the lighting industry, however, many products still make use of mercury, for different reasons. The main reason is that mercury-containing products are, in most cases, more efficient than mercury-free products. For a realistic comparison of the environmental impact, the mercury-contamination due to electricity production must be taken into account, which depends on the type of fuel being used. For an average European fuel-mix, the amount of mercury that is released into the environment is around 29 μg kWh-1. This means that a typical 30 W TL lamp during a lifetime of 20,000 hours will release a total of about 20 mg mercury due to electricity production, which exceeds the total mercury dose in the lamp (more and more of which is being recycled) by a factor of 5-10 for a modern TL lamp. This illustrates that, quite apart from other environmental arguments like increased CO2 production, mercury-free alternatives that use more energy can in fact be detrimental for the total mercury pollution over the lifetime of the lamp. For this reason, the lighting industry has concentrated on lowering the mercury content in lamps as long as no efficient alternatives exist. Nevertheless, new initiatives for HID lamps and fluorescent lamps with more or less equal efficiency are underway, and a number of them are described in this

  3. Rapid Monitoring of Mercury in Air from an Organic Chemical Factory in China Using a Portable Mercury Analyzer

    OpenAIRE

    Yasutake, Akira; Cheng, Jin Ping; Kiyono, Masako; Uraguchi, Shimpei; Liu, Xiaojie; Miura, Kyoko; Yasuda, Yoshiaki; Mashyanov, Nikolay

    2011-01-01

    A chemical factory, using a production technology of acetaldehyde with mercury catalysis, was located southeast of Qingzhen City in Guizhou Province, China. Previous research showed heavy mercury pollution through an extensive downstream area. A current investigation of the mercury distribution in ambient air, soils, and plants suggests that mobile mercury species in soils created elevated mercury concentrations in ambient air and vegetation. Mercury concentrations of up to 600 ng/m3 in air o...

  4. Multiscale geomorphometric modeling of Mercury

    Science.gov (United States)

    Florinsky, I. V.

    2018-02-01

    Topography is one of the key characteristics of a planetary body. Geomorphometry deals with quantitative modeling and analysis of the topographic surface and relationships between topography and other natural components of landscapes. The surface of Mercury is systematically studied by interpretation of images acquired during the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. However, the Mercurian surface is still little explored by methods of geomorphometry. In this paper, we evaluate the Mercury MESSENGER Global DEM MSGR_DEM_USG_SC_I_V02 - a global digital elevation model (DEM) of Mercury with the resolution of 0.015625° - as a source for geomorphometric modeling of this planet. The study was performed at three spatial scales: the global, regional (the Caloris basin), and local (the Pantheon Fossae area) ones. As the initial data, we used three DEMs of these areas with resolutions of 0.25°, 0.0625°, and 0.015625°, correspondingly. The DEMs were extracted from the MESSENGER Global DEM. From the DEMs, we derived digital models of several fundamental morphometric variables, such as: slope gradient, horizontal curvature, vertical curvature, minimal curvature, maximal curvature, catchment area, and dispersive area. The morphometric maps obtained represent peculiarities of the Mercurian topography in different ways, according to the physical and mathematical sense of a particular variable. Geomorphometric models are a rich source of information on the Mercurian surface. These data can be utilized to study evolution and internal structure of the planet, for example, to visualize and quantify regional topographic differences as well as to refine geological boundaries.

  5. 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

  6. Formation of Fluorohydroxyapatite with Silver Diamine Fluoride.

    Science.gov (United States)

    Mei, M L; Nudelman, F; Marzec, B; Walker, J M; Lo, E C M; Walls, A W; Chu, C H

    2017-09-01

    Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared-calcium phosphate (CaCl 2 ·2H 2 O + K 2 HPO 4 in buffer solution) and SDF (Ag[NH 3 ] 2 F in buffer solution). After incubation at 37 o C for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with

  7. Fluoride accumulation in soil and vegetation in the vicinity of brick fields.

    Science.gov (United States)

    Jha, S K; Nayak, A K; Sharma, Y K; Mishra, V K; Sharma, D K

    2008-04-01

    Fluoride in the soil and vegetation in the vicinity of brick field in the suburb of Lucknow, India was estimated. The water soluble fluoride (1:1) in the surface soil ranged from 0.59 ppm to 2.74 ppm where as CaCl(2) extractable fluoride ranged from 0.69 ppm to 3.18 ppm. The mean total fluoride concentration in surface soil varied from 322 microg g(-1) to 456 microg g(-1). The local vegetations grown in the area found to accumulate air borne fluoride from the brick field. The fluoride accumulation in the vegetation followed the order Mentha arvensis > Spinacea oleracea > Luffa cylindrical.

  8. The efficacy of amine fluoride/stannous fluoride in the suppression of morning breath odour.

    Science.gov (United States)

    Quirynen, Marc; Avontroodt, Pieter; Soers, Catherine; Zhao, Hong; Pauwels, Martine; Coucke, Wim; van Steenberghe, Daniel

    2002-10-01

    Breath odour is a complaint encountered worldwide, often linked to microbial overload in the oral cavity. This double blind, crossover, randomised study assessed the efficacy of several antiseptic mouthrinses or slurry vs. a control solution in the prevention of morning bad breath during an experimental period of 7 days without mechanical plaque control. Sixteen dental students with a healthy periodontium abolished, after a thorough professional cleaning, all means of mechanical plaque control during five experimental periods of 7 days, interleaved by washout periods of at least 3 weeks. During each experimental period, as the only oral hygiene measure, the students rinsed twice a day with one of the following formulations (in a randomised order): a 0.2% chlorhexidine-alcohol mouthrinse (CHX-Alc), a 0.05% CHX + 0.05% cetylpyridinium chloride + 0.14% zinc lactate mouthrinse (CHX-CPC-Zn), an amine fluoride/stannous fluoride (125 ppm F-/125 ppm F-) containing mouthrinse (AmF/SnF2Mr), a slurry of a tooth paste (AmF/SnF2Sl) containing amine fluoride (350 ppm F-) and stannous fluoride (1050 ppm F-) and a placebo solution (placebo). At days 0, 3 and 7, morning breath was scored via VSC level measurements of the mouth air, and organoleptic ratings of the mouth air and tongue coating. At the same visits both the degree of gingival inflammation and the de novo plaque formation were rated. At the end of each period a questionnaire for subjective ratings was completed and microbiological samples were taken from the tongue dorsum, the saliva and the supragingival plaque for anaerobic and aerobic culturing. Although oral hygiene during the experimental periods was limited to rinsing, bad breath parameters systematically improved (P or= 0.5 log reduction with a superiority (P plaque formation was significantly (P products. The CHX-Alc solution scored significantly worse for the subjective evaluation (questionnaires) concerning taste and sensitivity of tongue). The results of this

  9. Colorimetric determination of the fluoride ion - application to uranium metal and to uranous fluoride

    International Nuclear Information System (INIS)

    Hering, H.; Hure, J.; Legrand, S.

    1949-12-01

    In the determination described for fluoride in U metal, the U is brought into H 2 SO 4 solution by anodic oxidation, the fluo-silicic acid is distilled by entrainment in water vapor, and the F ion is determined in the distillate by using the fact that it complexes Zr and thus prevents the formation of the Zr-alizarin S lake. For F ion in UF 4 , the compound is dissolved in a Na 2 CO 3 -H 2 O 2 mixture, and F is determined in the solution by the colorimetric method described. (author)

  10. Method to separate hydrogen fluoride from an uranium hexafluoride-hydrogen fluoride mixture

    International Nuclear Information System (INIS)

    Pfistermeister, M.; Jokar, J.

    1978-01-01

    It is difficult to separate off HF in the purification of UF 6 from additional compounds. According to the invention, it is possible without too greater effort to form the hardly volatile tri-(perfluorobutyl)-ammonium fluoride by adding a perfluorate amine or a derivate of it, and then to separate off the UF 6 from the adduct by simple distillation or sublimation. The adduct can be easily split again with NaOH, so that the amine can be used again without loss. (RW) [de

  11. Method to separate off hydrogen fluoride from a uranium hexafluoride-hydrogen fluoride mixture

    International Nuclear Information System (INIS)

    Pfistermeister, M.; Jokar, J.

    1979-01-01

    There have been sofar difficulties involved in separating off HF when purifying UF 6 . According to the invention, this can be achieved without great expenditure if one adds a perfluorated amine or derivative of it to the UF 6 -HF mixture. The UF 6 can be separated by simple distillation or sublimation from the hardly-volatile formed tri-(perfluoro-butyl) ammonium fluoride. The adduct formed can be easily split again with NaOH so that the amine can be recycled without loss. (UWI) [de

  12. Maternal transfer of mercury to songbird eggs.

    Science.gov (United States)

    Ackerman, Joshua T; Hartman, C Alex; Herzog, Mark P

    2017-11-01

    We evaluated the maternal transfer of mercury to eggs in songbirds, determined whether this relationship differed between songbird species, and developed equations for predicting mercury concentrations in eggs from maternal blood. We sampled blood and feathers from 44 house wren (Troglodytes aedon) and 34 tree swallow (Tachycineta bicolor) mothers and collected their full clutches (n = 476 eggs) within 3 days of clutch completion. Additionally, we sampled blood and feathers from 53 tree swallow mothers and randomly collected one egg from their clutches (n = 53 eggs) during mid to late incubation (6-10 days incubated) to evaluate whether the relationship varied with the timing of sampling the mother's blood. Mercury concentrations in eggs were positively correlated with mercury concentrations in maternal blood sampled at (1) the time of clutch completion for both house wrens (R 2  = 0.97) and tree swallows (R 2  = 0.97) and (2) during mid to late incubation for tree swallows (R 2  = 0.71). The relationship between mercury concentrations in eggs and maternal blood did not differ with the stage of incubation when maternal blood was sampled. Importantly, the proportion of mercury transferred from mothers to their eggs decreased substantially with increasing blood mercury concentrations in tree swallows, but increased slightly with increasing blood mercury concentrations in house wrens. Additionally, the proportion of mercury transferred to eggs at the same maternal blood mercury concentration differed between species. Specifically, tree swallow mothers transferred 17%-107% more mercury to their eggs than house wren mothers over the observed mercury concentrations in maternal blood (0.15-1.92 μg/g ww). In contrast, mercury concentrations in eggs were not correlated with those in maternal feathers and, likewise, mercury concentrations in maternal blood were not correlated with those in feathers (all R 2  mercury concentrations from maternal blood to eggs

  13. Recovery of Mercury From Contaminated Liquid Wastes

    International Nuclear Information System (INIS)

    1998-01-01

    The Base Contract program emphasized the manufacture and testing of superior sorbents for mercury removal, testing of the sorption process at a DOE site, and determination of the regeneration conditions in the laboratory. During this project, ADA Technologies, Inc. demonstrated the following key elements of a successful regenerable mercury sorption process: (1) sorbents that have a high capacity for dissolved, ionic mercury; (2) removal of ionic mercury at greater than 99% efficiency; and (3) thermal regeneration of the spent sorbent. ADA's process is based on the highly efficient and selective sorption of mercury by noble metals. Contaminated liquid flows through two packed columns that contain microporous sorbent particles on which a noble metal has been finely dispersed. A third column is held in reserve. When the sorbent is loaded with mercury to the point of breakthrough at the outlet of the second column, the first column is taken off-line and the flow of contaminated liquid is switched to the second and third columns. The spent column is regenerated by heating. A small flow of purge gas carries the desorbed mercury to a capture unit where the liquid mercury is recovered. Laboratory-scale tests with mercuric chloride solutions demonstrated the sorbents' ability to remove mercury from contaminated wastewater. Isotherms on surrogate wastes from DOE's Y-12 Plant in Oak Ridge, Tennessee showed greater than 99.9% mercury removal. Laboratory- and pilot-scale tests on actual Y-12 Plant wastes were also successful. Mercury concentrations were reduced to less than 1 ppt from a starting concentration of 1,000 ppt. The treatment objective was 50 ppt. The sorption unit showed 10 ppt discharge after six months. Laboratory-scale tests demonstrated the feasibility of sorbent regeneration. Results show that sorption behavior is not affected after four cycles

  14. Worldwide trend of atmospheric mercury since 1995

    Directory of Open Access Journals (Sweden)

    F. Slemr

    2011-05-01

    Full Text Available Concern about the adverse effects of mercury on human health and ecosystems has led to tightening emission controls since the mid 1980s. But the resulting mercury emissions reductions in many parts of the world are believed to be offset or even surpassed by the increasing emissions in rapidly industrializing countries. Consequently, concentrations of atmospheric mercury are expected to remain roughly constant. Here we show that the worldwide atmospheric mercury concentrations have decreased by about 20 to 38 % since 1996 as indicated by long-term monitoring at stations in the Southern and Northern Hemispheres combined with intermittent measurements of latitudinal distribution over the Atlantic Ocean. The total reduction of the atmospheric mercury burden of this magnitude within 14 years is unusually large among most atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant anthropogenic emissions over this period. This suggests a major shift in the biogeochemical cycle of mercury including oceans and soil reservoirs. Decreasing reemissions from the legacy of historical mercury emissions are the most likely explanation for this decline since the hypothesis of an accelerated oxidation rate of elemental mercury in the atmosphere is not supported by the observed trends of other trace gases. Acidification of oceans, climate change, excess nutrient input and pollution may also contribute by their impact on the biogeochemistry of ocean and soils. Consequently, models of the atmospheric mercury cycle have to include soil and ocean mercury pools and their dynamics to be able to make projections of future trends.

  15. Mercury Methylation and Detoxification by Novel Microorganisms in Mercury Enriched Mesothermal Springs

    Science.gov (United States)

    Gionfriddo, C. M.; Krabbenhoft, D. P.; Stott, M.; Wick, R. R.; Schultz, M. B.; Holt, K. E.; Moreau, J. W.

    2015-12-01

    Hot springs and fumaroles release significant quantities of aqueous and gaseous mercury into the environment. Yet few studies have looked at the microbial underpinnings of mercury transformations in geothermal settings. Recent advancements in culture-independent molecular techniques, such as ultra-high-throughput sequencing, allow us to delve deeply into the functional and phylogenetic make-up of these extreme environments. Here we present results from deep metagenomic sequencing of geothermal microbial communities cycling mercury, focussing on the connections between putative metabolisms and mercury methylation, and the evolution of the mer-operon. Presented are data from two adjacent, acidic (pHNew Zealand), extremely enriched in total mercury (>1000 ng L-1), and varying methylmercury concentrations (1-10 ng L-1). Microbial communities of both springs are dominated by mercury resistant acidophilic, sulfur- and iron-cycling microbes: Acidithiobacillus, Thiomonas, and Thermoplasma. Mercury methylation genes (hgcAB) were only detected in the cooler spring (ΔT~10 °C), with an order of magnitude greater methylmercury (10 ng L-1). The hgcAB genes have no known closest relatives (40°C), and methylmercury concentration. We conclude that the relative amount of mercury methylation in each hot spring is controlled by the presence of methylating bacteria and archaea, the release of bioavailable mercury species from sulfide minerals, counterbalanced by microbial mercury demethylation and reduction and mercury sulfide mineralization.

  16. Mercury rising : mercury emissions from Ontario Power Generation's coal-fired plants

    International Nuclear Information System (INIS)

    Rang, S.

    2004-09-01

    Ontario Power Generation (OPG) operates 5 coal-fired power plants which are the largest single source of mercury emissions in Ontario. Mercury is a persistent, bioaccumulative neurotoxin which is considered toxic under the Canadian Environmental Protection Act. This report examines the health and environmental impacts of mercury, and the trends for mercury emission in Ontario. In 2002, the 5 coal-fired plants emitted 527 kg of mercury into the atmosphere and contributed 39 per cent of the total amount of mercury emitted into the air. While many other sectors have reduced their mercury emissions since 1988, Ontario's coal-fired plants have lagged behind and have actually increased mercury emissions by 16 per cent since 1988. This paper suggests that phasing out OPG coal-fired plants by 2007 could lead to a 39 per cent reduction in airborne mercury emissions. It would also allow Ontario to achieve the Canada Wide Standard for mercury emissions 3 years early, and would help both Ontario and Canada meet air pollution reduction commitments under international agreements. It was noted that phasing out coal-fired power plants by one-third will help Ontario achieve its goal of a 90 per cent reduction in mercury emissions by 2010. It was suggested that alternative power sources can offer a wide range of environmental advantages. 16 refs., 3 tabs., 2 figs

  17. Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2

    Energy Technology Data Exchange (ETDEWEB)

    Tuzen, Mustafa, E-mail: m.tuzen@gmail.com [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Uluozlu, Ozgur Dogan [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Karaman, Isa [Gaziosmanpasa University, Faculty of Science and Arts, Biology Department, 60250 Tokat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey)

    2009-09-30

    A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L{sup -1} HCl for methyl mercury and 2 mol L{sup -1} HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g{sup -1}. The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L{sup -1}. Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

  18. Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2

    International Nuclear Information System (INIS)

    Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Karaman, Isa; Soylak, Mustafa

    2009-01-01

    A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L -1 HCl for methyl mercury and 2 mol L -1 HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g -1 . The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L -1 . Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

  19. Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

    Energy Technology Data Exchange (ETDEWEB)

    Bacquart, Thomas [Better Life Laboratories, Calais, VT (United States); Frisbie, Seth [Better Life Laboratories, Calais, VT (United States); Department of Chemistry and Biochemistry, Norwich University, Northfield, VT (United States); Mitchell, Erika [Better Life Laboratories, Calais, VT (United States); Grigg, Laurie [Department of Earth and Environmental Science, Norwich University, Northfield, VT (United States); Cole, Christopher [Department of Chemistry and Biochemistry, Norwich University, Northfield, VT (United States); Small, Colleen [Vermont Department of Health Laboratory, Burlington, VT (United States); Sarkar, Bibudhendra, E-mail: bsarkar@sickkids.ca [Department of Molecular Structure and Function, The Research Institute of The Hospital for Sick Children, University of Toronto, Toronto, Ontario (Canada); Department of Biochemistry, University of Toronto, Toronto, Ontario (Canada)

    2015-06-01

    In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

  20. Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

    International Nuclear Information System (INIS)

    Bacquart, Thomas; Frisbie, Seth; Mitchell, Erika; Grigg, Laurie; Cole, Christopher; Small, Colleen; Sarkar, Bibudhendra

    2015-01-01

    In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

  1. Effect of sodium fluoride on bone density in chickens.

    Science.gov (United States)

    Lundy, M W; Russell, J E; Avery, J; Wergedal, J E; Baylink, D J

    1992-05-01

    In addition to increasing bone volume, fluoride has been demonstrated to increase ash weight and mineral density. To determine whether newly formed or older bone is most affected by fluoride treatment, bone from chickens receiving fluoridated water was fractionated into lower density (recently formed) and higher density (more mature) specific gravity fractions. Fluoride was administered to the chickens for different lengths of time (4 or 13 weeks) or at varying doses for a 4-week period (0, 4.2, 16.8 mmol/liter drinking water). Fluoride treatment caused a shift in the mineral density profile, showing an increased proportion of mineral distribution in the more mature, higher density fractions. To determine whether this density gradient shift was due to increased maturation rate of bone or decreased resorption and mineralization rates, [3H]proline and 45Ca were injected 5 days and 24 hours prior to sacrifice, respectively. The distributions of both 3H or 45Ca, as percentages of total counts incorporated, were shifted by fluoride treatment into more mature, higher density fractions. Expressing the number of counts as a percent of the bone in each fraction (total hydroxyproline or Ca) revealed an increased incorporation of both 3H and 45Ca into the higher specific gravity fractions 2.0-2.2. These results suggest that fluoride treatment increases bone maturation and the rate of secondary mineralization in the cortical bone. Such changes in the quality of more mature, well-mineralized bone, in humans as well as animals, may have a significant influence on brittleness and strength.

  2. 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.

  3. Fluoride potentiates tubulointerstitial nephropathy caused by unilateral ureteral obstruction.

    Science.gov (United States)

    Kido, Takamasa; Tsunoda, Masashi; Sugaya, Chiemi; Hano, Hiroshi; Yanagisawa, Hiroyuki

    2017-12-01

    The contamination of ground water by fluoride has been reported worldwide. Most fluoride (approximately 70%) is filtered by the kidneys; humans or experimental animals with renal damage therefore may be more affected by fluoride exposure than those with normal kidney function. Tubulointerstitial fibrosis, which involves macrophage-promoted extracellular matrix production and myofibroblast migration, can be induced in rats by unilateral ureteral obstruction (UUO). We examined the effects of fluoride exposure on tubulointerstitial fibrosis in the obstructed kidney of UUO rats. The left ureters of 6-week-old male rats were ligated using silk sutures. Fluoride was then administered for 2 weeks at doses of 0, 75, and 150ppm in the drinking water. Real-time polymerase chain reaction was performed to analyze transforming growth factor beta 1 (TGF-β 1 ) transcription; histological and immunohistochemical staining were used to identify positive areas within the renal cortex and staining-positive cells by image analysis. Significant increases were observed in the obstructed kidneys of UUO rats exposed to 150ppm fluoride (compared to 0ppm) for areas or number of cells that stained with Masson trichrome or with antibodies against collagen type I, alpha-smooth muscle actin (α-SMA, a myofibroblast marker), ED1, ED2, and ED3 (macrophage markers), and TGF-β 1 . Taken together, these observations suggested that fluoride exacerbates tuburointerstitial nephropathy resulting from UUO, and that this effect occurs via activation of the M2 macrophage-TGF-β1-fibroblast/myofibroblast-collagen synthesis pathway. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Human Exposure and Health Effects of Inorganic and Elemental Mercury

    Science.gov (United States)

    Zheng, Wei

    2012-01-01

    Mercury is a toxic and non-essential metal in the human body. Mercury is ubiquitously distributed in the environment, present in natural products, and exists extensively in items encountered in daily life. There are three forms of mercury, i.e., elemental (or metallic) mercury, inorganic mercury compounds, and organic mercury compounds. This review examines the toxicity of elemental mercury and inorganic mercury compounds. Inorganic mercury compounds are water soluble with a bioavailability of 7% to 15% after ingestion; they are also irritants and cause gastrointestinal symptoms. Upon entering the body, inorganic mercury compounds are accumulated mainly in the kidneys and produce kidney damage. In contrast, human exposure to elemental mercury is mainly by inhalation, followed by rapid absorption and distribution in all major organs. Elemental mercury from ingestion is poorly absorbed with a bioavailability of less than 0.01%. The primary target organs of elemental mercury are the brain and kidney. Elemental mercury is lipid soluble and can cross the blood-brain barrier, while inorganic mercury compounds are not lipid soluble, rendering them unable to cross the blood-brain barrier. Elemental mercury may also enter the brain from the nasal cavity through the olfactory pathway. The blood mercury is a useful biomarker after short-term and high-level exposure, whereas the urine mercury is the ideal biomarker for long-term exposure to both elemental and inorganic mercury, and also as a good indicator of body burden. This review discusses the common sources of mercury exposure, skin lightening products containing mercury and mercury release from dental amalgam filling, two issues that happen in daily life, bear significant public health importance, and yet undergo extensive debate on their safety. PMID:23230464

  5. Diffusion of hydrogen fluoride in solid parahydrogen.

    Science.gov (United States)

    Ooe, Hiroki; Miyamoto, Yuki; Kuma, Susumu; Kawaguchi, Kentarou; Nakajima, Kyo; Nakano, Itsuo; Sasao, Noboru; Tang, Jian; Taniguchi, Takashi; Yoshimura, Motohiko

    2013-06-07

    We studied diffusion of hydrogen fluoride (HF) in solid parahydrogen (pH2) around 4 K. Diffusion rates were determined from time dependence of FT-IR spectra of HF monomers. The absorption of HF monomers shows temporal decay due to dimerization reaction via diffusion. It was found that the rates are affected by the sample temperature, the initial HF concentration, and annealing of samples. The observed non-Arrhenius-type temperature dependence suggests that the diffusion is dominated by a quantum tunneling process, that is, "quantum diffusion." Deceleration of the diffusion in condensed samples and acceleration in annealed samples were also observed. These results can be attributed to the fact that lower periodicity of samples due to impurities or defects suppresses the quantum tunneling. It seems to be difficult to explain the observed dependences by three possible diffusion mechanisms, exchange of chemical bonds, direct cyclic exchange, and exchange with mobile vacancy. Therefore, we propose a hypothetical mechanism by exchange of vacancies originating from quantum effect.

  6. Deuterium fluoride laser technology and demonstrators

    Science.gov (United States)

    Wilson, Gerald; Graves, Bruce R.; Patterson, Stanley P.; Wank, Robert H.

    2004-09-01

    Deuterium fluoride (DF) lasers have been under development since about 1970. Their intrinsic ability to store high levels of energy internally plus their ability to quickly dispose of waste heat by the convective flow of exhaust gases make this type of laser attractive to the Army for producing high power levels for an air and missile defense weapon system. This paper reviews the basic principles of a DF laser, the chemistry and spectroscopy associated with producing an excited DF lasing molecule, and the generation of a high power laser beam. This paper also reviews the development history of DF lasers and early lethality demonstrations. This includes a detailed discussion of the Army"s recent Tactical High Energy Laser (THEL) Demonstrator, its architecture and successes during engagements of in-flight rockets and artillery projectiles. The Army is moving forward in developing a new generation, high power DF laser weapon system, the Mobile Tactical High Energy Laser (MTHEL). This system will provide our soldiers protection in the future against a variety of airborne threats.

  7. Ground-State of Hydrogen Fluoride

    Science.gov (United States)

    Bowen, Samuel P.; Fessatidis, Vassilios; Celi, Christina; Mancini, Jay D.

    2001-03-01

    The study of the ground-state properties of molecular systems has long been the focus of both quantum chemists as well as physicists. In general, most of the calculational methods are dependent on the use of high-power computers to generate large basis states. Such schemes as the full-configuration-interaction method, coupled-pair functionals and its modification, Moller-Plesset perturbation theory as well as both the restricted and unrestricted Hartree-Fock schemes have been used not only for ground-state calculations but also to calculate electron correlation energies. In general such schemes are limited to those bases which are constructed from single Slatter determinant. Here we wish to study the ground-state of hydrogen fluoride(HF) using the recently developed canonical sequence scheme which is a calculational cousin of the Connected Moments Expansion of Cioslowski. Comparisons are then made with other methods [for example P.J. Knowles Chem. Phys. Lett. 134, 512 (1987)].

  8. Advanced Carbon Fluorides For Primary Lithium Batteries

    Directory of Open Access Journals (Sweden)

    Guérin K.

    2017-01-01

    Full Text Available Li-CFx battery using a specific fluorinated nanocarbon as cathode material exhibits a capacity exceeding the expected theoretical value when used as an electrode material in primary lithium battery. Carbon nanodiscs were partially fluorinated by atomic fluorine released by thermal decomposition of TbF4, and the capacity of this material was up to 1180 mAh.g−1, whereas a theoretical value of 847 mAh.g−1 for the CF0.95 sample was calculated. The obtained value is also higher than the maximum one of 865 mAh.g−1 expected for CF1 carbon fluorides. The discharge mechanism was investigated using mainly SEM and solid state NMR in order to understand this “extracapacity”. Both the unfluorinated carbon and the LiF covering, which is formed outside the carbon lattice during the discharge mechanism, play a key role for the achievement of the extracapacity by the consumption of Li+ to form Li2F+ species stabilized by the carbon host structure formed after the electrochemical defluorination.

  9. Sexual differences in the excretion of organic and inorganic mercury by methyl mercury-treated rats

    International Nuclear Information System (INIS)

    Thomas, D.J.; Fisher, H.L.; Sumler, M.R.; Mushak, P.; Hall, L.L.

    1987-01-01

    Adult male and female Long Evans rats received 1 mumole of methyl ( 203 Hg) mercuric chloride per kilogram sc. Whole-body retention of mercury and excretion of organic and inorganic mercury in urine and feces were monitored for 98 days after dosing. Females cleared mercury from the body more rapidly than did males. The major route of mercury excretion was feces. By 98 days after dosing, cumulative mercury excretion in feces accounted for about 51% of the dose in males and about 54% of the dose in females. For both sexes, about 33% of the dose was excreted in feces as inorganic mercury. Cumulative excretion of organic mercury in feces accounted for about 18 and 21% of the dose in males and females, respectively. Urinary excretion of mercury was quantitatively a smaller route for mercury clearance but important sexual differences in loss by this route were found. Over the 98-day experimental period, males excreted in urine about 3.2% of the dose and females excreted 7.5%. Cumulative organic Hg excretion in urine accounted for 1.8% of the dose in males and 5.3% of the dose in females. These sexual differences in urinary and fecal excretion of organic and inorganic mercury following methyl mercury treatment were consistent with previous reports of sexual differences in mercury distribution and retention in methyl mercury-treated rats, particularly sexual differences in organic mercury uptake and retention in the kidney. Relationships between body burdens of organic or inorganic Hg and output of these forms of Hg in urine and feces were also found to be influenced by the interval after MeHg treatment and by sex. Relationship between concentration of Hg in liver and feces and in kidney and urine differed for organic and inorganic Hg and depended upon sexual status and interval after MeHg treatment

  10. Groundwater fluoride contamination, probable release, and containment mechanisms: a review on Indian context.

    Science.gov (United States)

    Mukherjee, Indrani; Singh, Umesh Kumar

    2018-03-23

    Fluoride contamination in the groundwater has got great attention in last few decades due to their toxicity, persistent capacity and accumulation in human bodies. There are several sources of fluoride in the environment and different pathways to enter in the drinking water resources, which is responsible for potential effect on human health. Presence of high concentration of fluoride ion in groundwater is a major issue and it makes the water unsuitable for drinking purpose. Availability of fluoride in groundwater indicates various geochemical processes and subsurface contamination of a particular area. Fluoride-bearing aquifers, geological factors, rate of weathering, ion-exchange reaction, residence time and leaching of subsurface contaminants are major responsible factors for availability of fluoride in groundwater. In India, several studies have reported that the groundwater of several states are contaminated with high fluoride. The undesirable level of fluoride in groundwater is one of the most natural groundwater quality problem, which affects large portion of arid and semiarid regions of India. Rajasthan, Andhra Pradesh, Telangana, Tamil Nadu, Gujarat, and West Bengal are the relatively high-fluoride-contaminated states in India. Chronic ingestion of high doses of fluoride-rich water leads to fluorosis on human and animal. Over 66 million Indian populations are at risk due to excess fluoride-contaminated water. Therefore, groundwater contamination subject to undesirable level of fluoride needs urgent attention to understand the role of geochemistry, hydrogeology and climatic factors along with anthropogenic inputs in fluoride pollution.

  11. Increased Mercury Bioaccumulation Follows Water Quality Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Bogle, M.A.; Peterson, M.J.; Smith, J.G.; Southworth, G.R.

    1999-09-15

    Changes in physical and chemical characteristics of aquatic habitats made to reduce or eliminate ecological risks can sometimes have unforeseen consequences. Environmental management activities on the U.S. Dept. of Energy reservation in Oak Ridge, Tennessee,have succeeded in improving water quality in streams impacted by discharges fi-om industrial facilities and waste disposal sites. The diversity and abundance of pollution-sensitive components of the benthic macroinvertebrate communities of three streams improved after new waste treatment systems or remedial actions reduced inputs of various toxic chemicals. Two of the streams were known to be mercury-contaminated from historical spills and waste disposal practices. Waterborne mercury concentrations in the third were typical of uncontaminated systems. In each case, concentrations of mercury in fish, or the apparent biological availability of mercury increased over the period during which ecological metrics indicated improved water quality. In the system where waterborne mercury concentrations were at background levels, increased mercury bioaccumulation was probably a result of reduced aqueous selenium concentrations; however, the mechanisms for increased mercury accumulation in the other two streams remain under investigation. In each of the three systems, reduced inputs of metals and inorganic anions was followed by improvements in the health of aquatic invertebrate communities. However, this reduction in risk to aquatic invertebrates was accompanied by increased risk to humans and piscivorous wildlife related to increased mercury concentrations in fish.

  12. Increased Mercury Bioaccumulation Follows Water Quality Improvement

    International Nuclear Information System (INIS)

    Bogle, M.A.; Peterson, M.J.; Smith, J.G.; Southworth, G.R.

    1999-01-01

    Changes in physical and chemical characteristics of aquatic habitats made to reduce or eliminate ecological risks can sometimes have unforeseen consequences. Environmental management activities on the U.S. Dept. of Energy reservation in Oak Ridge, Tennessee,have succeeded in improving water quality in streams impacted by discharges fi-om industrial facilities and waste disposal sites. The diversity and abundance of pollution-sensitive components of the benthic macroinvertebrate communities of three streams improved after new waste treatment systems or remedial actions reduced inputs of various toxic chemicals. Two of the streams were known to be mercury-contaminated from historical spills and waste disposal practices. Waterborne mercury concentrations in the third were typical of uncontaminated systems. In each case, concentrations of mercury in fish, or the apparent biological availability of mercury increased over the period during which ecological metrics indicated improved water quality. In the system where waterborne mercury concentrations were at background levels, increased mercury bioaccumulation was probably a result of reduced aqueous selenium concentrations; however, the mechanisms for increased mercury accumulation in the other two streams remain under investigation. In each of the three systems, reduced inputs of metals and inorganic anions was followed by improvements in the health of aquatic invertebrate communities. However, this reduction in risk to aquatic invertebrates was accompanied by increased risk to humans and piscivorous wildlife related to increased mercury concentrations in fish

  13. A Challenging Case of Acute Mercury Toxicity

    Directory of Open Access Journals (Sweden)

    Ali Nayfeh

    2018-01-01

    Full Text Available Background. Mercury exists in multiple forms: elemental, organic, and inorganic. Its toxic manifestations depend on the type and magnitude of exposure. The role of colonoscopic decompression in acute mercury toxicity is still unclear. We present a case of acute elemental mercury toxicity secondary to mercury ingestion, which markedly improved with colonoscopic decompression. Clinical Case. A 54-year-old male presented to the ED five days after ingesting five ounces (148 cubic centimeters of elemental mercury. Examination was only significant for a distended abdomen. Labs showed elevated serum and urine mercury levels. An abdominal radiograph showed radiopaque material throughout the colon. Succimer and laxatives were initiated. The patient had recurrent bowel movements, and serial radiographs showed interval decrease of mercury in the descending colon with interval increase in the cecum and ascending colon. Colonoscopic decompression was done successfully. The colon was evacuated, and a repeat radiograph showed decreased hyperdense material in the colon. Three months later, a repeat radiograph showed no hyperdense material in the colon. Conclusion. Ingested elemental mercury can be retained in the colon. Although there are no established guidelines for colonoscopic decompression, our patient showed significant improvement. We believe further studies on this subject are needed to guide management practices.

  14. The influence of floodplains on mercury availability

    Energy Technology Data Exchange (ETDEWEB)

    Wallschlaeger, D.; Wilken, R.D. [GKSS Research Center, Geesthacht (Germany). Inst. of Physical and Chemical Analytics

    1997-09-01

    The floodplains of the German river Elbe affect the mercury distribution in the river system in two different ways: they act both as a medium-term sink and as a long-term source. The large amounts of mercury deposited onto the floodplains during annual floodings are first effectively fixed in the soils, rendering them basically unavailable. Sequential extraction experiments reveal that only a small fraction of the mercury (< 3%) is present in available forms, whereas the vast majority is associated with humic substances or present in sulfidic binding forms. After deposition, a small fraction of the total mercury is gradually remobilized into the aqueous phase bound passively to water-soluble humic acids. The availability of mercury in these complexes is still low, since environmental influences such as changes in pH or redox potential and competition with other cations do not cause any mercury liberation. In the next step, reactions in the aqueous phase lead to the formation of the highly available volatile species Hg{sup 0} and dimethylmercury (DMM). Their evaporation gives rise to a strong mercury flux from the floodplains into the atmosphere. Preliminary mass balances indicate that the majority of the deposited mercury stays bound in the floodplain soils, while small amounts are emitted back into the river`s ecosystem. Atmospheric emission is more important as a remobilization pathway than aquatic export.

  15. OCCURENCE OF MERCURY IN PET FOOD

    Directory of Open Access Journals (Sweden)

    M.C. Abete

    2013-02-01

    Full Text Available Mercury levels in 61 complete pet feed containing fish were evaluated. In five samples a mercury content exceeding the maximum residues level (0.4 mg/kg was detected. The statistical evaluation didn’t show a significant correlation between the percentage of fish in feedingstuffs and the contamination level.

  16. Hair mercury measurement in Egyptian autistic children

    African Journals Online (AJOL)

    Farida El-baz

    Abstract Background: A review of medical literature has shown that exposure to mercury, whether organic or inorganic, can give rise to the symptoms and traits defining or commonly found in autism spectrum disorders (ASD). Mercury can cause impairments in social interaction, commu- nication difficulties, and repetitive ...

  17. Terahertz oscillations in mercury cuprate superconductors

    Indian Academy of Sciences (India)

    Abstract. It has been recently reported that the three-dimensional Bose–Einstein con- densation of the quasi-particles is valid for the mercury cuprates at liquid helium tem- perature. In this study, the validity of the interlayer theory in three dimensions has been investigated for optimally oxygen-doped mercury cuprates at the ...

  18. Mercury poisoning | Shamley | South African Medical Journal

    African Journals Online (AJOL)

    The diagnosis of mercury poisoning requires a high index of suspicion. Mercury poisoning in a patient involved in illicit gold extraction is reported and 6 other cases considered. Some of the clinical features and treatment of this condition are discussed. S Afr Med J 1989; 76: 114-116 ...

  19. Mercury soil surveys: a good reconnaissance tool

    Energy Technology Data Exchange (ETDEWEB)

    Stone, C.; Ruscetta, C.A.; Foley, D. (eds.)

    1981-05-01

    Three examples of mercury soil surveys are discussed, along with the gravity data. An excellent correlation was found in southern Arizona between buried structures revealed by gravity and mercury soil surveys. The advantages of the latter over the former as a reconnaissance tool are listed. (MHR)

  20. Intentional intravenous mercury injection | Yudelowitz | South African ...

    African Journals Online (AJOL)

    Intravenous mercury injection is rarely seen, with few documented cases. Treatment strategies are not clearly defined for such cases, although a few options do show benefit. This case report describes a 29-year-old man suffering from bipolar disorder, who presented following self-inflicted intravenous injection of mercury.