WorldWideScience

Sample records for bromine fluorides

  1. Bromine

    Czech Academy of Sciences Publication Activity Database

    Pavelka, Stanislav

    2. Weinheim : WileyVCH, 2004 - (Merian, E.; Anke, M.; Ihnat, M.; Stoeppler, M.), s. 1445-1455 ISBN 3-527-30459-2. - (3) Institutional research plan: CEZ:AV0Z5011922 Keywords : bromine * analysis * biological relevance Subject RIV: CA - Inorganic Chemistry

  2. Fluoride

    Science.gov (United States)

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

  3. Bromine Safety

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, B

    2001-04-09

    The production and handling in 1999 of about 200 million kilograms of bromine plus substantial derivatives thereof by Great Lakes Chemical Corp. and Albemarle Corporation in their southern Arkansas refineries gave OSHA Occupational Injury/Illness Rates (OIIR) in the range of 0.74 to 1.60 reportable OIIRs per 200,000 man hours. OIIRs for similar industries and a wide selection of other U.S. industries range from 1.6 to 23.9 in the most recent OSHA report. Occupational fatalities for the two companies in 1999 were zero compared to a range in the U.S.of zero for all computer manufacturing to 0.0445 percent for all of agriculture, forestry and fishing in the most recent OSHA report. These results show that bromine and its compounds can be considered as safe chemicals as a result of the bromine safety standards and practices at the two companies. The use of hydrobromic acid as an electrical energy storage medium in reversible PEM fuel cells is discussed. A study in 1979 of 20 megawatt halogen working fluid power plants by Oronzio de Nora Group found such energy to cost 2 to 2.5 times the prevailing base rate at that time. New conditions may reduce this relative cost. The energy storage aspect allows energy delivery at maximum demand times where the energy commands premium rates. The study also found marginal cost and performance advantages for hydrobromic acid over hydrochloric acid working fluid. Separate studies in the late 70s by General Electric also showed marginal performance advantages for hydrobromic acid.

  4. Fluoridated Water

    Science.gov (United States)

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

  5. Bottled Water and Fluoride

    Science.gov (United States)

    ... Fluoridation Journal Articles for Community Water Fluoridation Bottled Water Recommend on Facebook Tweet Share Compartir Consumers drink ... questions about bottled water and fluoride. Does bottled water contain fluoride? Bottled water products may contain fluoride, ...

  6. Metal fluorides

    International Nuclear Information System (INIS)

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

  7. Fluoridation Basics

    Science.gov (United States)

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

  8. How Does Fluoride Work?

    Science.gov (United States)

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

  9. Fluoride and Dental Health

    OpenAIRE

    Nikiforuk, Gordon

    1988-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    OpenAIRE

    Paul S; Tandon S; Murthy K

    1993-01-01

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

  12. 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

  13. Two new brominated diterpenes from Laurencia decumbens

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Two new brominated diterpenes, namely, laurendecumtriol and 11-deacetylpinnaterpene C, were isolated and identified from the marine red alga Laurencia decumbens. Their structures were established on the basis of various NMR spectroscopic techniques and HR-ESI-MS analyses.

  14. Bromine accumulation in acidic black colluvial soils

    Science.gov (United States)

    Cortizas, Antonio Martínez; Vázquez, Cruz Ferro; Kaal, Joeri; Biester, Harald; Casais, Manuela Costa; Rodríguez, Teresa Taboada; Lado, Luis Rodríguez

    2016-02-01

    Recent investigations showed that bromine is incorporated to soil organic matter (SOM), its content increasing with humification. But few research was done on its long-term accumulation and the role played by pedogenetic processes, as those involved in organic matter stabilization. We investigated bromine content and distribution in four deep, acidic, organic-rich, Holocene soils from an oceanic area of Western Europe. Bromine concentrations (93-778 μg g-1) in the silt + clay (area, and total estimated retention was low (6-16%). The degree of SOM bromination, expressed as the Br/C molar ratio, varied between 0.03 and 1.20 mmol Br/mol C. The ratio was highly correlated (n = 23, r2 0.88, p pool of metal-clay-stabilized organic matter.

  15. Fluoride levels and osteosarcoma

    Directory of Open Access Journals (Sweden)

    Simmi Kharb

    2012-01-01

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

  16. Fluoride toothpastes and fluoride mouthrinses for home use

    OpenAIRE

    Andrew Rugg-Gunn; Jolan Bánóczy

    2013-01-01

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

  17. 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. PMID:27352462

  18. Fluoride varnishes and enamel caries

    OpenAIRE

    De Bruyn, Hugo

    1987-01-01

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

  19. 40 CFR 721.3085 - Brominated phthalate ester.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated phthalate ester. 721.3085... Substances § 721.3085 Brominated phthalate ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as brominated phthalate ester (PMN P-90-581)...

  20. 40 CFR 721.9740 - Brominated triazine derivative.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated triazine derivative. 721... Substances § 721.9740 Brominated triazine derivative. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated triazine...

  1. Fluoride and Water (For Parents)

    Science.gov (United States)

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

  2. Hormonal activities of new brominated flame retardants

    Czech Academy of Sciences Publication Activity Database

    Ezechiáš, Martin; Svobodová, Kateřina; Cajthaml, Tomáš

    2012-01-01

    Roč. 87, č. 7 (2012), s. 820-824. ISSN 0045-6535 R&D Projects: GA ČR GA104/09/0694 Institutional research plan: CEZ:AV0Z50200510 Keywords : Brominated flame retardants * 2,4,6-Tribromophenol * Endocrine disruptors Subject RIV: EE - Microbiology, Virology Impact factor: 3.137, year: 2012

  3. The cariostatic mechanisms of fluoride

    OpenAIRE

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

    2013-01-01

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

  4. Fluoride in diet

    Science.gov (United States)

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

  5. Fluoride toothpastes and fluoride mouthrinses for home use

    Directory of Open Access Journals (Sweden)

    Andrew Rugg-Gunn

    2013-11-01

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

  6. Symproportionation versus Disproportionation in Bromine Redox Systems

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: • The disproportionation and symproportionation of bromine in different media is presented. • All the redox systems are elaborated according to the principles of the generalized approach to electrolytic redox systems (GATES/GEB). • All physicochemical knowledge is involved in the algorithm applied for this purpose. • The graphical representation of the systems is the basis of gaining the detailed physicochemical knowledge on the systems in question. -- Abstract: The paper refers to dynamic (titration) redox systems where symproportionation or disproportionation of bromine species occur. The related systems are modeled according to principles assumed in the Generalized Approach to Electrolytic Redox Systems (GATES), with Generalized Electron Balance (GEB) concept involved in the GATES/GEB software. The results obtained from calculations made with use of iterative computer programs prepared according to MATLAB computational software, are presented graphically, as 2D and 3D graphs

  7. Membrane-less hydrogen bromine flow battery

    CERN Document Server

    Braff, W A; Buie, C R

    2014-01-01

    In order for the widely discussed benefits of flow batteries for electrochemical energy storage to be applied at large scale, the cost of the electrochemical stack must come down substantially. One promising avenue for reducing stack cost is to increase the system power density while maintaining efficiency, enabling smaller stacks. Here we report on a membrane-less, hydrogen bromine laminar flow battery as a potential high power density solution. The membrane-less design enables power densities of 0.795 W cm$^{-2}$ at room temperature and atmospheric pressure, with a round-trip voltage efficiency of 92\\% at 25\\% of peak power. Theoretical solutions are also presented to guide the design of future laminar flow batteries. The high power density achieved by the hydrogen bromine laminar flow battery, along with the potential for rechargeable operation, will translate into smaller, inexpensive systems that could revolutionize the fields of large-scale energy storage and portable power systems.

  8. Brominated flame retardants and endocrine disruption

    OpenAIRE

    Vos, J G; Becher, G; Berg, van den, C.A.; Boer; Leonards, P.E.G.

    2003-01-01

    From an environmental point of view, an increasing important group of organohalogen compounds are the brominated flame retardants (BFRs), which are widely used in polymers and textiles and applied in construction materials, furniture, and electronic equipment. BFRs with the highest production volume are the polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBP-A), and hexabromocyclododecane (HBCD). Because of their persistence and low biodegradation profile, several of the PBDE ...

  9. 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...

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

    OpenAIRE

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

    2003-01-01

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

  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 pH and...

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

    OpenAIRE

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

    2011-01-01

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

  13. Controlled Grafting of Poly(methyl methacrylate) Brushes on Poly(vinylidene fluoride) Powders by Surface-initiated Atom Transfer Radical Polymerization

    Institute of Scientific and Technical Information of China (English)

    TANG Zhaoqi; LI Wei; LIU Lanqin; HUANG Lei; ZHOU Jin; YU Haiyin

    2009-01-01

    Controlled grafting of well-defined polymer brushes of methyl methacrylate (MMA) on the poly(vinylidene fluoride) (PVDF) powders was carded out by the surface-initiated atom transfer radical polymerization (ATRP). The ATRP initiator was anchored on the PVDF surface by alkaline treatment, followed by UV-induced bromination; then methyl methacrylate (MMA) was grafted onto the brominated PVDF by the ATRP technique. The chemical composition changes of PVDF were characterized by Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS results clearly indicated the successful graft of poly(methyl methacrylate) onto the PVDF surface.

  14. Brominated thiophenes as precursors in the preparation of brominated and arylated anthraquinones.

    Science.gov (United States)

    Thiemann, Thies; Tanaka, Yasuko; Iniesta, Jesus

    2009-01-01

    Brominated anthraquinones can be synthesized directly from bromothiophenes when these are reacted with 1,4-naphthoquinones in the presence of meta-chloroperoxybenzoic acid. The bromoanthraquinones are versatile building blocks in the preparation of arylated anthraquinones and of extended pi-systems with interspersed anthraquinone units. PMID:19305356

  15. Brominated Thiophenes as Precursors in the Preparation of Brominated and Arylated Anthraquinones

    Directory of Open Access Journals (Sweden)

    Thies Thiemann

    2009-03-01

    Full Text Available Brominated anthraquinones can be synthesized directly from bromothiophenes when these are reacted with 1,4-naphthoquinones in the presence of meta-chloroperoxybenzoic acid. The bromoanthraquinones are versatile building blocks in the preparation of arylated anthraquinones and of extended π-systems with interspersed anthraquinone units.

  16. Brominated Thiophenes as Precursors in the Preparation of Brominated and Arylated Anthraquinones

    OpenAIRE

    Thies Thiemann; Jesus Iniesta; Yasuko Tanaka

    2009-01-01

    Brominated anthraquinones can be synthesized directly from bromothiophenes when these are reacted with 1,4-naphthoquinones in the presence of meta-chloroperoxybenzoic acid. The bromoanthraquinones are versatile building blocks in the preparation of arylated anthraquinones and of extended π-systems with interspersed anthraquinone units.

  17. Other Fluoride Products

    Science.gov (United States)

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

  18. The BRomine, Ozone, and Mercury EXperiment (BROMEX)

    Science.gov (United States)

    Nghiem, S. V.; Shepson, P. B.; Simpson, W. R.; Perovich, D. K.; Sturm, M.; Douglas, T. A.; Rigor, I. G.; Clemente-Colon, P.; Burrows, J. P.; Richter, A.; Bottenheim, J. W.; Steffen, A.; Barber, D. G.; Kaleschke, L.; Hall, D. K.; Markus, T.; Eicken, H.; Neumann, G.

    2011-12-01

    In the decade of the 2000s, Arctic perennial (multi-year) sea ice has diminished drastically, whereas seasonal (first-year) sea ice has become the dominant ice class. This change effectively increases the overall surface salinity of the sea ice cover and in the overlying snowpack. Satellite results in 2010 and 2011 show the extent of perennial sea ice remains minimal with significant bromine explosions in the springtime. Key science questions still remain to be answered to understand the impact of the Arctic perennial sea ice reduction on low-atmospheric physical and chemical processes. Of the highest priority is to investigate the impact on bromine explosion events that lead to depletion of ozone and gaseous elementary mercury in the atmosphere. With that objective, we present the development of the BRomine, Ozone, and Mercury EXperiment in (BROMEX) in spring 2012 around Barrow, extending out to 200 km offshore and inland. In BROMEX, chemical, sea ice, snow, and ocean measurements will be made across sea ice leads both upwind and downwind areas of newly opened leads. Chemical-measurement buoys and other types of buoys will be deployed with helicopter flights to both sides of the leads. Various flight patterns of aircraft carrying ozone and bromine-measuring sensors will be used to characterize the chemical distribution over sea ice, land, and mountainous regions. Our approach will use data from multiple satellite instruments including MODIS, AMSR-E, QuikSCAT, GOME-2, SCIAMACHY, OMI, RADARSAT-2, Envisat ASAR, TerraSAR-X, TanDEM-X, SMOS, CryoSat-2 altimeter, and Oceansat-2 scatterometer. Moreover, results from recent field campaigns such as the IPY OASIS, INCATPA, CFL, SALT, and IceBridge, from sea ice and snow products generated by the U.S. Naval and National Ice Center, from NASA cryospheric observations, and from surface observation networks such as SIZONet will be utilized together with new measurements from BROMEX. Further collaborations with the international

  19. Synthesis, physical and chemical properties, and potential applications of graphite fluoride fibers

    Science.gov (United States)

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

    1987-01-01

    Graphite fluoride fibers can be produced by fluorinating pristine or intercalated graphite fibers. The higher the degree of graphitization of the fibers, the higher the temperature needed to reach the same degree of fluorination. Pitched based fibers were fluorinated to flourine-to-carbon atom rations between 0 and 1. The graphite fluoride fibers with a fluorine-to-carbon atom ration near 1 have extensive visible structural damage. On the other hand, fluorination of fibers pretreated with bromine or fluorine and bromine result in fibers with a fluorine-to-carbon atom ratio nearly equal to 0.5 with no visible structural damage. The electrical resistivity of the fibers is dependent upon the fluorine to carbon atom ratio and ranged from .01 to 10 to the 11th ohm/cm. The thermal conductivity of these fibers ranged from 5 to 73 W/m-k, which is much larger than the thermal conductivity of glass, which is the regular filler in epoxy composites. If graphite fluoride fibers are used as a filler in epoxy or PTFE, the resulting composite may be a high thermal conductivity material with an electrical resistivity in either the insulator or semiconductor range. The electrically insulating product may provide heat transfer with lower temperature gradients than many current electrical insulators. Potential applications are presented.

  20. 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.

  1. Formation of THMs and HANs during bromination of Microcystis aeruginosa

    Institute of Scientific and Technical Information of China (English)

    Yunzhu Pu; Lingzhao Kong; Xin Huang; Guoji Ding; Naiyun Gao

    2013-01-01

    Bromine-contained disinfectants and biocides are widely used in swimming pools,recreational waters and cooling towers.The objective of this study was to evaluate the formation of thrihalomethanes (THMs) and haloacetonitriles (HANs) and their cytotoxicity in algae solutions during free bromine disinfection.Disinfection by-products formation potential experiments were conducted using modelsolutions containing 7mg/L (as total organic carbon) Microcystis aeruginosa cells.Effects of free bromine dosage,pH and ammonia were investigated.The results showed that brominated disinfection by-products were the major products when free bromine was applied.The total THMs formed during bromination was much as that formed during chlorination,whereas HANs were elevated by using bromination instead of chlorination.Dibromoacetonitrice (C2H2NBr2) and bromoform (CHBr3) were the only detected species during free bromine disinfection.The production of C2H2NBr2 and CHBr3 increased with disinfectant dosage but decreased with dosing ammonia.CHBr3 increased with the pH changing from 5 to 9.However,C2H2NBr2 achieved the highest production at neutral pH,which was due to a joint effect of variation in hydrolysis rate and free bromine reactivity.The hydrolysis of C2H2NBr2 was basecatalytic and nearly unaffected by disinfectant.Finally,estimation of cytotoxicity of the disinfected algae solutions showed that HANs formation was responsible for the majority of toxicity.Considering its highest toxicity among the measured disinfection by-products,the elevated C2H2NBr2 should be considered when using bromine-related algaecide.

  2. New infrared spectroscopic database for bromine nitrate

    Science.gov (United States)

    Wagner, Georg; Birk, Manfred

    2016-08-01

    Fourier transform infrared measurements of bromine nitrate have been performed in the spectral region 675-1400 cm-1 at 0.014 cm-1 spectral resolution. Absorption cross sections were derived from 38 spectra covering the temperature range from 203 to 296 K and air pressure range from 0 to 190 mbar. For line-by-line analysis, further spectra were recorded at 0.00094 cm-1 spectral resolution at 223 and 293 K. The sample was synthesized from ClONO2 and Br2. Band strengths of the bands ν3 around 803 cm-1 and ν2 around 1286 cm-1 were determined from three pure BrONO2 measurements at different temperatures and pressures. Number densities in the absorption cell were derived from pressure measurements of the purified sample taking into account small amounts of impurities determined spectroscopically. Resulting band strengths are Sν3 = 2.872(52) × 10-17 cm2 molec-1 cm-1 and Sν2 = 3.63(15) × 10-17 cm2 molec-1 cm-1. Absorption cross sections of all measurements were scaled to these band strengths. Further data reduction was achieved with an interpolation scheme based on two-dimensional polynomials in ln(pressure) and temperature. The database is well-suited for remote-sensing application and should reduce the atmospheric bromine nitrate error budget substantially.

  3. Water fluoridation and oral health

    Directory of Open Access Journals (Sweden)

    Máiréad Antoinette Harding

    2013-11-01

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

  4. Health Effects Associated with Water Fluoridation.

    Science.gov (United States)

    Richmond, Virginia L.

    1979-01-01

    Discussion is presented concerning fluoridation of water supplies. Correlation between fluoride in drinking water and improved dental health is reviewed. Relationship is expressed between fluoridation and reduced tooth decay. Use of fluoride in treating skeletal disorders is discussed. Author advocates fluoridating water supplies. (SA)

  5. Fluoride and dental caries

    OpenAIRE

    Camilleri, George E.

    1998-01-01

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

  6. Fluoride in dental erosion

    OpenAIRE

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

    2011-01-01

    Dental erosion develops through chronic exposure to extrinsic/intrinsic acids with a low pH. Enamel erosion is characterized by a centripetal dissolution leaving a small demineralized zone behind. In contrast, erosive demineralization in dentin is more complex as the acid-induced mineral dissolution leads to the exposure of collagenous organic matrix, which hampers ion diffusion and, thus, reduces further progression of the lesion. Topical fluoridation inducing the formation of a protective l...

  7. Strontium-90 fluoride data sheet

    International Nuclear Information System (INIS)

    This report is a compilation of available data and appropriate literature references on the properties of strontium-90 fluoride and nonradioactive strontium fluoride. The objective of the document is to compile in a single source pertinent data to assist potential users in the development, licensing, and use of 90SrF2-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977

  8. Fluoride remediation using floating macrophytes

    OpenAIRE

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

    2014-01-01

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

  9. Ruthenium-Catalyzed meta-Selective C—H Bromination

    Science.gov (United States)

    Teskey, Christopher J; Lui, Andrew Y W; Greaney, Michael F

    2015-01-01

    The first example of a transition-metal-catalyzed, meta-selective C–H bromination procedure is reported. In the presence of catalytic [{Ru(p-cymene)Cl2}2], tetrabutylammonium tribromide can be used to functionalize the meta C–H bond of 2-phenylpyridine derivatives, thus affording difficult to access products which are highly predisposed to further derivatization. We demonstrate this utility with one-pot bromination/arylation and bromination/alkenylation procedures to deliver meta-arylated and meta-alkenylated products, respectively, in a single step. PMID:26288217

  10. Ruthenium-Catalyzed meta-Selective C—H Bromination

    OpenAIRE

    Teskey, Christopher J; Lui, Andrew Y W; Greaney, Michael F.

    2015-01-01

    The first example of a transition-metal-catalyzed, meta-selective C–H bromination procedure is reported. In the presence of catalytic [{Ru(p-cymene)Cl2}2], tetrabutylammonium tribromide can be used to functionalize the meta C–H bond of 2-phenylpyridine derivatives, thus affording difficult to access products which are highly predisposed to further derivatization. We demonstrate this utility with one-pot bromination/arylation and bromination/alkenylation procedures to deliver meta-arylated and...

  11. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

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

  12. Magnetic Trapping of Cold Bromine Atoms

    CERN Document Server

    Rennick, C J; Doherty, W G; Softley, T P

    2014-01-01

    Magnetic trapping of bromine atoms at temperatures in the milliKelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br$_2$ molecules in a molecular beam. The lab-frame velocity of Br atoms is controlled by the wavelength and polarization of the photodissociation laser. Careful selection of the wavelength results in one of the pair of atoms having sufficient velocity to exactly cancel that of the parent molecule, and it remains stationary in the lab frame. A trap is formed at the null point between two opposing neodymium permanent magnets. Dissociation of molecules at the field minimum results in the slowest fraction of photofragments remaining trapped. After the ballistic escape of the fastest atoms, the trapped slow atoms are only lost by elastic collisions with the chamber background gas. The measured loss rate is consistent with estimates of the total cross section for only those collisions transferring sufficient kinetic energy to overcome the trapping potential...

  13. The metabolism and de-bromination of bromotyrosine in vivo

    NARCIS (Netherlands)

    A.R. Mani (Ali); J.C. Moreno (José C.); T.J. Visser (Theo J.); K.P. Moore (Kevin P.)

    2016-01-01

    textabstractDuring inflammation, leukocyte-derived eosinophil peroxidase catalyses the formation of hypobromous acid, which can brominate tyrosine residues in proteins to form bromotyrosine. Since eosinophils are involved in the pathogenesis of allergic reactions, such as asthma, urinary bromotyrosi

  14. Bromine number should replace FIA in gasoline olefins testing

    International Nuclear Information System (INIS)

    Fluorescent indicator adsorption (FIA) analysis, the ASTM test method proposed by the U.S. Environmental Protection Agency (EPA) for monitoring olefins in reformulated gasoline, is subject to significant bias and imprecision. This paper reports on a more accurate, environmentally pertinent measure of olefin content in reformulated gasoline is bromine number another ASTM method. Petroleum chemists should therefore work together with the EPA to select and optimize a bromine number procedure specifically designed for reformulated gasoline to replace FIA

  15. Private Well Water and Fluoride

    Science.gov (United States)

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

  16. 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…

  17. 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...

  18. Molten fluoride fuel salt chemistry

    International Nuclear Information System (INIS)

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established

  19. Probing the tropical tropopause layer for organic and inorganic bromine

    Science.gov (United States)

    Werner, Bodo; Pfeilsticker, Klaus; Atlas, Elliot; Cheung, Ross; Chipperfield, Martyn; Colosimo, Fedele; Deutschmann, Tim; Elkins, Jim; Fahey, David; Feng, Wu; Festa, James; Gao, Ru-Shan; Hossaini, Ryan; Navarro, Maria; Raecke, Rasmus; Scalone, Lisa; Spolaor, Max; Thornberry, Troy; Tsai, Catalina; Stutz, Jochen

    2016-04-01

    Bromine chemistry impacts the levels of ozone in the upper troposphere and the stratosphere. An accurate quantitative understanding of the sources, sinks, and chemical transformation of bromine species is thus important to understand the photochemistry and budget of bromine in the tropical upper troposphere, tropopause layer and lowermost stratosphere (UT/TTL/LS). These regions are also known to serve as a gateway for delivery of ozone depleting gases to the stratosphere. CH3Br, halons, short-lived organic bromine precursors (VSLS), such as CHBr3, CH2Br2, and possibly inorganic product gases have been identified as the main bromine gases delivered to the stratosphere. However, many important details of the transport and delivery of VSLS and inorganic bromine compounds through the TTL are still uncertain. Moreover, a number of chemical processes, including the transformation of the source gases and cycling of inorganic bromine species at low ambient temperature and on ice particles are also poorly understood. The presentation reports measurements of CH4, O3, NO2, and BrO performed by different instruments and techniques during the 2013 NASA-ATTREX flights in the TTL and LS. The interpretation of our measurements is supported by chemical transport model (SLIMCAT) simulations. SLIMCAT results, in conjunction with extensive radiative transfer calculations using the Monte Carlo model McArtim, also are used to improve retrieval of O3, NO2, and BrO concentrations from limb scattered sunlight measurements made with the Differential Optical Absorption Spectroscopy (DOAS) technique during ATTREX. The chemical transport model also allows us to attribute observed concentration variations to transport and to photochemical processes. When properly accounting for the transport-related concentration variations in methane and ozone, we find that measured BrO mostly agrees with model simulations. An exception are regions where the contribution of the short-lived CH2Br2 or the

  20. Bromine pretreated chitosan for adsorption of lead (II) from water

    Indian Academy of Sciences (India)

    Rajendra Dongre; Minakshi Thakur; Dinesh Ghugal; Jostna Meshram

    2012-10-01

    Pollution by heavy metals like lead (II) is responsible for health hazards and environmental degradation. Adsorption is a prevalent method applied for removal of heavy metal pollutants from water. This study explored adsorption performances of 30% bromine pretreated chitosan for lead (II) abatement from water. Bromine pretreatment alters porosity and specific surface area of chitosan by means of physicochemical interaction with cationic sites of chitosan skeleton, besides imparting anionic alteration at amino linkages of chitosan, to remove lead (II) by chemical interactions on superfluous active sites as characterized by FTIR, SEM, DTA and elemental analysis. Lead adsorptions were studied in batch mode by varying parameters viz. pH, bromine loading, sorbent dosage, initial lead concentration, contact time and temperature. The adsorption equilibrium data was well fitted to Freundlich isotherm and maximum sorption capacity of 30% bromine pretreated chitosan sorbent was 1.755 g/kg with 85–90% lead removal efficiency. Though cost and applicability of sorbent is unproven, yet contrast to raw chitosan derivatives, activated carbons and some resins, 30% bromine pretreated chitosan endow benign and efficient lead abatement technique.

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

    OpenAIRE

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

    2008-01-01

    A biomarker for lifetime fluoride exposure would facilitate population-based research and policy making but currently does not exist. This study examined the suitability of primary tooth dentin as a biomarker by comparing dentin fluoride concentration and fluoride exposures. Ninety-nine children's exfoliated primary teeth were collected from 2 fluoridated and 2 fluoride-deficient communities in North Carolina. Coronal dentin was isolated by microdissection and fluoride concentration assayed u...

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

    OpenAIRE

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

    2014-01-01

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

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

    OpenAIRE

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

    2009-01-01

    OBJECTIVE: This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to DuraphatTM. MATERIAL AND METHODS: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, s...

  4. Levels and trends of brominated flame retardants in the European environment

    NARCIS (Netherlands)

    Law, R.J.; Allchin, C.R.; Boer, de J.; Covaci, A.; Herzke, D.; Lepom, P.; Morris, S.; Tronczynski, J.; Wit, de C.A.

    2006-01-01

    In this paper, we review those data which have recently become available for brominated flame retardants (particularly the brominated diphenyl ethers (BDEs) and hexabromocyclododecane (HBCD)) in samples from the European environment. Environmental compartments studied comprise the atmosphere, sedime

  5. Fluoride glass: Crystallization, surface tension

    Science.gov (United States)

    Doremus, R. H.

    1988-01-01

    Fluoride glass was levitated acoustically in the ACES apparatus on STS-11, and the recovered sample had a different microstructure from samples cooled in a container. Further experiments on levitated samples of fluoride glass are proposed. These include nucleation, crystallization, melting observations, measurement of surface tension of molten glass, and observation of bubbles in the glass. Ground experiments are required on sample preparation, outgassing, and surface reactions. The results should help in the development and evaluation of containerless processing, especially of glass, in the development of a contaminent-free method of measuring surface tensions of melts, in extending knowledge of gas and bubble behavior in fluoride glasses, and in increasing insight into the processing and properties of fluoride glasses.

  6. Chronic Fluoride Toxicity: Dental Fluorosis

    OpenAIRE

    DenBesten, Pamela; Li, Wu

    2011-01-01

    Dental fluorosis occurs as a result of excess fluoride ingestion during tooth formation. Enamel fluorosis and primary dentin fluorosis can only occur when teeth are forming, and therefore fluoride exposure (as it relates to dental fluorosis) occurs during childhood. In the permanent dentition, this would begin with the lower incisors, which complete mineralization at approximately 2–3 years of age, and end after mineralization of the third molars. The white opaque appearance of fluorosed enam...

  7. Method of aluminium fluoride manufacture

    International Nuclear Information System (INIS)

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

  8. The fluoride content of bottled drinking waters.

    Science.gov (United States)

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

    1994-04-01

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

  9. An Efficient and Facile Methodology for Bromination of Pyrimidine and Purine Nucleosides with Sodium Monobromoisocyanurate (SMBI

    Directory of Open Access Journals (Sweden)

    Roger Stromberg

    2013-10-01

    Full Text Available An efficient and facile strategy has been developed for bromination of nucleosides using sodium monobromoisocyanurate (SMBI. Our methodology demonstrates bromination at the C-5 position of pyrimidine nucleosides and the C-8 position of purine nucleosides. Unprotected and also several protected nucleosides were brominated in moderate to high yields following this procedure.

  10. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

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

    OpenAIRE

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

    2016-01-01

    It was the aim of this study to investigate differences in fluoride bioavailability in different oral areas after the application of amine fluoride (AmF) and sodium fluoride (NaF). The null hypothesis suggested no differences in the fluoride bioavailability. The tongue coating was removed and biofilm samples from the palate, oral floor and cheeks were collected. All subjects brushed their teeth with toothpaste containing AmF or NaF. Specimens were collected before, as well as immediately afte...

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

    Science.gov (United States)

    Krook, L; Maylin, G A

    1979-04-01

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

  13. Fluoridering af drikkevandet i Danmark?

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  14. Brominated Dioxins: Little-Known New Health Hazards - A Review

    Directory of Open Access Journals (Sweden)

    Piskorska-Pliszczyńska Jadwiga

    2014-10-01

    Full Text Available This article reviews the present state of the science concerning the polybrominated dibenzo-p-dioxins (PBDDs and dibenzofurans (PBDFs. Everywhere in the world people are exposed to anthropogenic origin chemicals. Some of them are long-lived organic compounds, which persist over the years in the environment. Persistent organic pollutants, such as organohalogen compounds, accumulate in environmental and biological compartments and have adverse effects on the health of humans and animals. Little is known about the brominated and mixed chloro/bromo dioxin and furans. Existing literature suggests that brominated dioxins and furans have similar toxicity profiles to their chlorinated analogues. The exposure data are extremely limited, showing a major data gap in estimating the potential environmental and health risk of these chemicals. The rapid increase in the use of brominated flame retardants (the main source of these pollutants has raised the level of concern over environmental and health damage from brominated dioxins and furans. It is likely that human as well as wildlife exposure to these contaminants will increase with their greater use. The findings reported here present strong evidence of the PBDDs and PBDFs as an emerging new class of contaminants.

  15. Ecotoxicity and biodegradability of new brominated flame retardants: A review

    Czech Academy of Sciences Publication Activity Database

    Ezechiáš, Martin; Covino, Stefano; Cajthaml, Tomáš

    2014-01-01

    Roč. 110, č. 2 (2014), s. 153-167. ISSN 0147-6513 R&D Projects: GA MŠk(CZ) EE2.3.30.0003; GA TA ČR TE01020218 Institutional support: RVO:61388971 Keywords : Ecotoxicity * brominated flame retardants * biodegradation * review Subject RIV: EE - Microbiology, Virology Impact factor: 2.762, year: 2014

  16. Discovery of Zinc, Selenium, Bromine, and Neodymium Isotopes

    OpenAIRE

    J.L. Gross; Claes, J.; Kathawa, J.; Thoennessen, M

    2010-01-01

    Currently, thirty-two zinc, thirty-two selenium, twenty-nine bromine and thirty-one neodymium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  17. 21 CFR 180.30 - Brominated vegetable oil.

    Science.gov (United States)

    2010-04-01

    ... “Food Chemicals Codex,” 3d Ed. (1981), pp. 40-41, which is incorporated by reference, except that free... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Brominated vegetable oil. 180.30 Section 180.30 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED)...

  18. Discovery of zinc, selenium, bromine, and neodymium isotopes

    International Nuclear Information System (INIS)

    Currently, thirty-two zinc, thirty-two selenium, twenty-nine bromine, and thirty-one neodymium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  19. Bromine provides new weapons to combat mercury emissions

    Energy Technology Data Exchange (ETDEWEB)

    Hardtke, W. [Albermarle Europe (Germany)

    2011-04-15

    Brominated powdered activated carbon has been demonstrated to capture over 90% of mercury emissions from coal fired plants, operating at high temperatures and capturing the metal in concrete-friendly, non-leaching forms to help tackle a rising global health threat. 6 refs., 5 figs.

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

    International Nuclear Information System (INIS)

    Uranium hexafluoride (UF6) released into the atmosphere will react rapidly with moisture in the air to form the hydrolysis products uranyl fluoride (UO2F2) and hydrogen fluoride (HF). Uranium compounds such as UF6 and UO2F2 exhibit both chemical toxicity and radiological effects, while HF exhibits only chemical toxicity. This paper describes the development of a methodology for assessing the human health consequences of a known acute exposure to a mixture of UF6, UO2F2, and HF. 4 refs., 2 figs., 5 tabs

  1. IMPACT OF FLUORIDE ON DENTAL HEALTH QUALITY

    OpenAIRE

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

    2015-01-01

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

  2. Alimentary fluoride intake in preschool children

    OpenAIRE

    Lencova Erika; Ivancakova Romana; Oganessian Edgar; Broukal Zdenek

    2011-01-01

    Abstract Background The knowledge of background alimentary fluoride intake in preschool children is of utmost importance for introducing optimal and safe caries preventive measures for both individuals and communities. The aim of this study was to assess the daily fluoride intake analyzing duplicate samples of food and beverages. An attempt was made to calculate the daily intake of fluoride from food and swallowed toothpaste. Methods Daily alimentary fluoride intake was measured in a group of...

  3. Molten fluorides for nuclear applications

    Directory of Open Access Journals (Sweden)

    Sylvie. Delpech

    2010-12-01

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

  4. Fluoride: its role in dentistry

    Directory of Open Access Journals (Sweden)

    Livia Maria Andaló Tenuta

    2010-01-01

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

  5. Bromine measurements in ozone depleted air over the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    J. A. Neuman

    2010-07-01

    Full Text Available In situ measurements of ozone, photochemically active bromine compounds, and other trace gases over the Arctic Ocean in April 2008 are used to examine the chemistry and geographical extent of ozone depletion in the arctic marine boundary layer (MBL. Data were obtained from the NOAA WP-3D aircraft during the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC study and the NASA DC-8 aircraft during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS study. Fast (1 s and sensitive (detection limits at the low pptv level measurements of BrCl and BrO were obtained from three different chemical ionization mass spectrometer (CIMS instruments, and soluble bromide was measured with a mist chamber. The CIMS instruments also detected Br2. Subsequent laboratory studies showed that HOBr rapidly converts to Br2 on the Teflon instrument inlets. This detected Br2 is identified as active bromine and represents a lower limit of the sum HOBr + Br2. The measured active bromine is shown to likely be HOBr during daytime flights in the arctic. In the MBL over the Arctic Ocean, soluble bromide and active bromine were consistently elevated and ozone was depleted. Ozone depletion and active bromine enhancement were confined to the MBL that was capped by a temperature inversion at 200–500 m altitude. In ozone-depleted air, BrO rarely exceeded 10 pptv and was always substantially lower than soluble bromide that was as high as 40 pptv. BrCl was rarely enhanced above the 2 pptv detection limit, either in the MBL, over Alaska, or in the arctic free troposphere.

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

    Directory of Open Access Journals (Sweden)

    Navabi B.

    2011-07-01

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

  7. Effect of fluoride on Treponema denticola.

    OpenAIRE

    Hughes, C A; Yotis, W W

    1986-01-01

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

  8. Fluoride in African groundwater: Occurrence and mitigation

    NARCIS (Netherlands)

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

    2010-01-01

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

  9. Ultraviolet transmission of fluoride glasses

    International Nuclear Information System (INIS)

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

  10. Why does bromine square palladium off? An ab initio study of brominated palladium and its nanomorphology.

    Science.gov (United States)

    Yoo, Su-Hyun; Lee, Ji-Hwan; Delley, Bernard; Soon, Aloysius

    2014-09-14

    A first-principles description and prediction of brominated nanocrystals of Pd is presented. In particular, we conducted an extensive study of the adsorption behaviour of Br on various Pd surfaces (including both low and high Miller-index surfaces) as a function of its surface coverage. By coupling our calculated surface energies with ab initio (electrochemical) thermodynamics and the Gibbs-Wulff shape model, we find that the relative stability of the Pd surfaces is strongly modified by Br, allowing high Miller-index surfaces of Pd (namely the (210) surface) to become competitively favourable at moderate concentrations of Br. We also show that Pd nanoparticles assume a cube-like crystal shape at high concentrations of Br, exposing mainly the (100) facets with a Br surface coverage of 0.5 ML. This not only confirms and explains recent solution synthesis results, but also provides a quantitative atomic picture of the exposed surface facets, which is crucial in understanding the local surface chemistry of shape-controlled nanoparticles for better nanocatalyst design. PMID:25075669

  11. Occurrence of bromine in fluidised bed combustion of solid recovered fuel

    Energy Technology Data Exchange (ETDEWEB)

    Vainikka, P.

    2011-12-15

    Corrosive ash species are the single most important factor limiting the electric efficiency of steam boiler plants fired with waste or biomass. Chlorine has been found to have a central role in the chemistry involved as it reduces the melting temperature of ash, forms corrosive vapour and gas species in the furnace and halogenated deposits on boiler heat transfer surfaces. In this context chlorine has been extensively researched. At the time of writing this thesis there was hardly any published data available on the occurrence of bromine (Br) in the aforementioned context. The objective of this work was to review the occurrence of bromine in solid fuels and characterise the behaviour of bromine in full-scale fluidised bed combustion. The review on the occurrence of bromine in solid fuels revealed that in anthropogenic wastes bromine is mainly found in connection to flame retarded substances. Several weight percentages of bromine can be found in plastics treated with brominated flame retardants (BFRs). Bromine is typically found some 100-200 mg kg-1 in mixed municipal solid wastes (MSW). Bromine may be enriched in fuels with high share of plastics, such as solid recovered fuel (SRF) or refuse derived fuel (RDF). Up to 2000 mg kg-1 was found as a monthly average in SRF, typical levels being 20-200 mg kg-1. Wastewater sludge from paper mills may contain bromine 20-100 mg kg-1 due the use of bromine based biocides. In other fuels bromine may be found in significant amounts in marine influenced coal deposits and peat as well as in biomass treated with brominated pesticides. In the experimental part SRF, spruce bark and wastewater sludge from a paper mill were co-fired in a full- scale bubbling fluidised bed (BFB) boiler, and the collected fuels, aerosols and waterwall deposits were analysed with the focus on the fate of bromine. Bromine was mainly found to form water soluble high vapour pressure alkali metal halides in the furnace - in the form of KBr(g) and NaBr(g) as

  12. Fluoride remediation using floating macrophytes

    Directory of Open Access Journals (Sweden)

    Naba Kumar Mondal

    2014-04-01

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

  13. Global affordability of fluoride toothpaste

    Directory of Open Access Journals (Sweden)

    Holmgren Christopher J

    2008-06-01

    Full Text Available Abstract Objective Dental caries remains the most common disease worldwide and the use of fluoride toothpaste is a most effective preventive public health measure to prevent it. Changes in diets following globalization contribute to the development of dental caries in emerging economies. The aim of this paper is to compare the cost and relative affordability of fluoride toothpaste in high-, middle- and low-income countries. The hypothesis is that fluoride toothpaste is not equally affordable in high-, middle- and low-income countries. Methods Data on consumer prices of fluoride toothpastes were obtained from a self-completion questionnaire from 48 countries. The cost of fluoride toothpaste in high-, middle- and low-income countries was compared and related to annual household expenditure as well as to days of work needed to purchase the average annual usage of toothpaste per head. Results The general trend seems to be that the proportion of household expenditure required to purchase the annual dosage of toothpaste increases as the country's per capita household expenditure decreases. While in the UK for the poorest 30% of the population only 0.037 days of household expenditure is needed to purchase the annual average dosage (182.5 g of the lowest cost toothpaste, 10.75 days are needed in Kenya. The proportion of annual household expenditure ranged from 0.02% in the UK to 4% in Zambia to buy the annual average amount of lowest cost toothpaste per head. Conclusion Significant inequalities in the affordability of this essential preventive care product indicate the necessity for action to make it more affordable. Various measures to improve affordability based on experiences from essential pharmaceuticals are proposed.

  14. Alimentary fluoride intake in preschool children

    Directory of Open Access Journals (Sweden)

    Lencova Erika

    2011-10-01

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

  15. Endocrine effects of some new brominated flame retardants

    Czech Academy of Sciences Publication Activity Database

    Ezechiáš, Martin; Svobodová, Kateřina; Cajthaml, Tomáš

    Praha : VŠCHT, 2012. s. 77-78. ISBN 978-80-7080-811-5. [Průmyslová ekologie /3./. 20.03.2012-23.03.2012, Hustopeče u Brna] R&D Projects: GA ČR GA104/09/0694 Institutional research plan: CEZ:AV0Z50200510 Keywords : Brominated flame retardants * Endocrine disruptors Subject RIV: EE - Microbiology, Virology

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

    Directory of Open Access Journals (Sweden)

    Daniela Correia Cavalcante SOUZA

    2014-08-01

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

  17. Measurement-based modeling of bromine chemistry in the boundary layer: 1. Bromine chemistry at the Dead Sea

    OpenAIRE

    Tas, E.; Peleg, M.; D. U. Pedersen; Matveev, V; Pour Biazar, A.; Luria, M.

    2006-01-01

    International audience The Dead Sea is an excellent natural laboratory for the investigation of Reactive Bromine Species (RBS) chemistry, due to the high RBS levels observed in this area, combined with anthropogenic air pollutants up to several ppb. The present study investigated the basic chemical mechanism of RBS at the Dead Sea using a numerical one-dimensional chemical model. Simulations were based on data obtained from comprehensive measurements performed at sites along the Dead Sea. ...

  18. High selectively oxidative bromination of toluene derivatives by the H2O2-HBr system

    Institute of Scientific and Technical Information of China (English)

    Jie Ju; Yu Jin Li; Jian Rong Gao; Jian Hong Jia; Liang Han; Wei Jian Sheng; Yi Xia Jia

    2011-01-01

    An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals. Various substituted toluenes (NO2,Cl, Br, H, CH3) were high selectively brominated at the benzyl position for monobromination in CH2C12 at ice water with catalyst free. This simple but effective bromination of toluene derivatives with an aqueous H2O2-HBr system is characterized with the use of inexpensive reagents and a lower impact on the environment, which make it a good alternative to the existing bromination methods.

  19. 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...

  20. Discovery of Interstellar Hydrogen Fluoride

    CERN Document Server

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

    1997-01-01

    We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2 - 1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of 3E-10 relative to H2. If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for ~ 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously...

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

    OpenAIRE

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

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography met...

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

    OpenAIRE

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

    2011-01-01

    The objective of the present research was to determine the appropriate amount of fluoride to use professional topical application and the residual amounts of fluoride in the oral cavity using a 2% neutral sodium fluoride (NaF) foam with a dedicated tray. Using dentition study models, a method for determining the appropriate amount of NaF foam was investigated. In eight adult subjects, the appropriate amount of NaF foam, the concentration of fluoride in the saliva following professional topica...

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

    OpenAIRE

    Nagpal D; Damle S

    2007-01-01

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

  4. Ruthenium olefin metathesis catalysts containing fluoride

    OpenAIRE

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

    2015-01-01

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

  5. 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...

  6. Fluoride bioavailability in saliva and plaque

    OpenAIRE

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

    2012-01-01

    Abstract Background Different fluoride formulations may have different effects on caries prevention. It was the aim of this clinical study to assess the fluoride content, provided by NaF compared to amine fluoride, in saliva and plaque. Methods Eight trained volunteers brushed their teeth in the morning for 3 minutes with either NaF or amine fluoride, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva and ...

  7. New insight into photo-bromination processes in saline surface waters: The case of salicylic acid

    International Nuclear Information System (INIS)

    It was shown, through a combination of field and laboratory observations, that salicylic acid can undergo photo-bromination reactions in sunlit saline surface waters. Laboratory-scale experiments revealed that the photochemical yields of 5-bromosalicylic acid and 3,5-dibromosalicylic acid from salicylic acid were always low (in the 4% range at most). However, this might be of concern since these compounds are potential inhibitors of the 20α-hydroxysteroid dehydrogenase enzyme, with potential implications in endocrine disruption processes. At least two mechanisms were involved simultaneously to account for the photo-generation of brominated substances. The first one might involve the formation of reactive brominated radical species (Br·, Br2·−) through hydroxyl radical mediated oxidation of bromide ions. These ions reacted more selectively than hydroxyl radicals with electron-rich organic pollutants such as salicylic acid. The second one might involve the formation of hypobromous acid, through a two electron oxidation of bromine ions by peroxynitrite. This reaction was catalyzed by nitrite, since these ions play a crucial role in the formation of nitric oxide upon photolysis. This nitric oxide further reacts with superoxide radical anions to yield peroxynitrite and by ammonium through the formation of N-bromoamines, probably due to the ability of N-bromoamines to promote the aromatic bromination of phenolic compounds. Field measurements revealed the presence of salicylic acid together with 5-bromosalicylic and 3,5-dibromosalicylic acid in a brackish coastal lagoon, thus confirming the environmental significance of the proposed photochemically induced bromination pathways. -- Highlights: ► Brominated derivatives of salicylic acid were detected in a brackish lagoon. ► A photochemical pathway was hypothesized to account for bromination of salicylic acid. ► Radical bromine species are partly responsible for the bromination process. ► Hypobromous acid might

  8. Gramicidin D enhances the antibacterial activity of fluoride

    OpenAIRE

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

    2014-01-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in B. subtilis and that the antibacterial activity of this compound...

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

    OpenAIRE

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

    2014-01-01

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

  10. Fluoride in cerebrospinal fluid of patients with fluorosis.

    OpenAIRE

    Hu, Y H; Wu, S S

    1988-01-01

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

  11. 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.

  12. Bayesian statistical modeling of disinfection byproduct (DBP) bromine incorporation in the ICR database.

    Science.gov (United States)

    Francis, Royce A; Vanbriesen, Jeanne M; Small, Mitchell J

    2010-02-15

    Statistical models are developed for bromine incorporation in the trihalomethane (THM), trihaloacetic acids (THAA), dihaloacetic acid (DHAA), and dihaloacetonitrile (DHAN) subclasses of disinfection byproducts (DBPs) using distribution system samples from plants applying only free chlorine as a primary or residual disinfectant in the Information Collection Rule (ICR) database. The objective of this study is to characterize the effect of water quality conditions before, during, and post-treatment on distribution system bromine incorporation into DBP mixtures. Bayesian Markov Chain Monte Carlo (MCMC) methods are used to model individual DBP concentrations and estimate the coefficients of the linear models used to predict the bromine incorporation fraction for distribution system DBP mixtures in each of the four priority DBP classes. The bromine incorporation models achieve good agreement with the data. The most important predictors of bromine incorporation fraction across DBP classes are alkalinity, specific UV absorption (SUVA), and the bromide to total organic carbon ratio (Br:TOC) at the first point of chlorine addition. Free chlorine residual in the distribution system, distribution system residence time, distribution system pH, turbidity, and temperature only slightly influence bromine incorporation. The bromide to applied chlorine (Br:Cl) ratio is not a significant predictor of the bromine incorporation fraction (BIF) in any of the four classes studied. These results indicate that removal of natural organic matter and the location of chlorine addition are important treatment decisions that have substantial implications for bromine incorporation into disinfection byproduct in drinking waters. PMID:20095529

  13. Accurate measurement of bromine contents in plastic samples by instrumental neutron activation analysis.

    Science.gov (United States)

    Kim, I J; Lee, K S; Hwang, E; Min, H S; Yim, Y H

    2013-03-26

    Accurate measurements of bromine contents in plastic samples were made by the direct comparator instrumental neutron activation analysis (INAA). Individual factors affecting the measurements were comprehensively evaluated and compensated, including the volatility loss of bromine from standard comparators, the background bromine level in the filter papers used for preparation of the standard comparators, nuclear interference, γ-ray spectral interference and the variance among replicates of the samples. Uncertainty contributions from those factors were thoroughly evaluated and included in the uncertainty budgeting of the INAA measurement. (81)Br was chosen as the target isotope, and the INAA measurements for bromine were experimentally confirmed to exhibit good linearity within a bromine content range of 10-170 μg. The established method has been applied to the analysis of eight plastic samples: four commercially available certified reference materials (CRMs) of polyethylene and polystyrene and four acrylonitrile butadiene styrene (ABS) samples prepared as the candidate reference materials (KRISS CRM 113-01-012, -013, -014 and -015). The bromine contents of the samples were calculated at three different γ-ray energies and compared, showing good agreement. The results of the four CRMs also showed good consistency with their certified values within the stated uncertainties. Finally, the bromine contents of the ABS samples were determined with expanded uncertainties (at a 95% level of confidence) between 2.5% and 5% in a bromine content range of 25-900 mg kg(-1). PMID:23498117

  14. The Evolution of a Green Chemistry Laboratory Experiment: Greener Brominations of Stilbene

    Science.gov (United States)

    McKenzie, Lallie C.; Huffman, Lauren M.; Hutchison, James E.

    2005-01-01

    The use of green metrics to compare three bromination laboratory procedures demonstrates the effectiveness of an incremental greening process for chemistry curricula. Due to this process, the bromination of alkenes can be introduced to students through the use of a safe, effective, modern practice.

  15. 40 CFR 721.775 - Brominated aromatic com-pound (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated aromatic com-pound (generic name). 721.775 Section 721.775 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.775 Brominated aromatic com-pound (generic name). (a)...

  16. Biosynthesis of brominated tyrosine metabolites by Aplysina fistularis.

    Science.gov (United States)

    Carney, J R; Rinehart, K L

    1995-07-01

    The biosynthesis of brominated tyrosine metabolites by the marine sponge Aplysina fistularis was investigated. [U-14C]-L-Tyrosine, [U-14C]-L-3-bromotyrosine, and [U-14C]-L-3,5-dibromotyrosine were incorporated into both dibromoverongiaquinol [1] and aeroplysinin-1 [2], and [methyl-14C]methionine was specifically incorporated into the O-methyl group group of 2. [Methyl-14C]-L-O-methyltyrosine, [methyl-14C]-L-3,5-dibromo-O-methyltyrosine, and several putative nitrile precursors were not incorporated into 1 or 2. PMID:7561906

  17. Future chlorine-bromine loading and ozone depletion

    Science.gov (United States)

    Prather, Michael J.; Ibrahim, Abdel Moneim; Sasaki, Toru; Stordal, Frode; Visconti, Guido

    1991-01-01

    The prediction of future ozone requires three elements: (1) a scenario for the net emissions of chemically and radiatively active trace gases from the land and oceans; (2) a global atmospheric model that projects the accumulation of these gases; and (3) a chemical transport model that describes the distribution of ozone for a prescribed atmospheric composition and climate. This chapter, of necessity, presents models for all three elements and focuses on the following: (1) atmospheric abundance of chlorine and bromine in the form of halocarbons; and (2) the associated perturbations to stratospheric ozone.

  18. Research on the phenomenon of graphitization. Crystallographic study - Study of bromine sorption

    International Nuclear Information System (INIS)

    This research thesis reports the study of the mechanism of graphitization of carbon by using X-ray diffraction analysis and the physical and chemical study of lamellar reactions between carbon and bromine. The author first presents generalities and results of preliminary studies (meaning of graphitization, presentation of the various carbon groups and classes), and then reports the study of the graphitization of compact carbons (soft carbons). More precisely, he reports the crystallographic study of partially graphitized carbons: methods and principles, experimental results and their analysis, discussion of the graphitization mechanism. In the next part, the author reports the study of bromine sorption on carbons: experimental method, isotherms of a natural graphite and of a graphitized carbon, structure of carbon-bromine complexes, isotherms of graphitizable carbons and of all other carbons, distribution of bromine layers in partially graphitized carbons, bromine sorption and Fermi level

  19. Labeling of receptor ligands with bromine radionuclides. Progress report, March 1, 1981-February 28, 1982

    International Nuclear Information System (INIS)

    In recent years there has been an interest in the use of various radioisotopes of bromine as labels for radiopharmaceuticals. Although radioisotopes of iodine have been used extensively as radiopharmaceutical labels, there are several advantages associated with the use of radiobromine as a label, due primarily to increased stability of bonds to the radiohalide and smaller steric perturbation resulting from substitution of the radiohalide. Methods of attaching radiobromine to receptor ligands with the potential of mapping estrogen receptors in mammary tumors and uteri were studied. Two ligands were studied extensively in vitro and in animal models; preliminary studies were also carried out in humans. To date, the only radioisotope of bromine used was bromine-77. In addition, a series of model compounds were labeled with bromine-77 using a recently described method for rapid bromination; the scope and limitations of this new rapid radiobromination technique were evaluated

  20. 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...... treatment method. A procedure for purification of fluoride contaminated magadi at household level is described....

  1. Growth of hollow nickel fluoride whiskers

    International Nuclear Information System (INIS)

    Hollow nickel fluoride whiskers have been obtained by condensation from the vapor phase onto a platinum substrate in a flow of hydrogen fluoride. Crystals up to 5 mm in length have a square cross section with a 300 ± 30-μm side. The wall thickness is 85 ± 20 μm.

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2007-01-01

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

  4. Niobium electrodeposition from molten fluorides

    International Nuclear Information System (INIS)

    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)

  5. Manufacture and properties of fluoride cement

    Science.gov (United States)

    Malata-Chirwa, Charles David

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

  6. Determination of Fluoride in Different Toothpaste Formulations

    International Nuclear Information System (INIS)

    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

  7. Substoichiometric precipitation of fluoride with lanthanum

    International Nuclear Information System (INIS)

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

  8. Recent advancements in fluoride: A systematic review

    Science.gov (United States)

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

    2015-01-01

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

  9. Method of treating fluoride contaminated wastes

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-04-05

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

  10. 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.

  11. Algae form brominated organic compounds in surface waters

    Energy Technology Data Exchange (ETDEWEB)

    Huetteroth, A.; Putschew, A.; Jekel, M. [Tech. Univ. Berlin (Germany)

    2004-09-15

    Monitoring of organic halogen compounds, measured as adsorbable organic bromine (AOBr) revealed seasonal high concentrations of organic bromine compounds in a surface water (Lake Tegel, Berlin, Germany). Usually, in late summer, concentrations are up to five times higher than during the rest of the year. The AOBr of the lake inflows (throughout the year less then 6 {mu}g/L) were always lower then those in the lake, which indicates a production of AOBr in the lake. A correlation of the AOBr and chlorophyll-a concentration (1) in the lake provides first evidence for the influence of phototrophic organisms. The knowledge of the natural production of organohalogens is relatively recent. Up to now there are more then 3800 identified natural organohalogen compounds that have been detected in marine plants, animals, and bacteria and also in terrestrial plants, fungi, lichen, bacteria, insects, some higher animals, and humans. Halogenated organic compounds are commonly considered to be of anthropogenic origin; derived from e.g. pharmaceuticals, herbicides, fungicides, insecticides, flame retardants, intermediates in organic synthesis and solvents. Additionally they are also produced as by-products during industrial processes and by waste water and drinking water disinfection. Organohalogen compounds may be toxic, persistent and/or carcinogenic. In order to understand the source and environmental relevance of naturally produced organobromine compounds in surface waters, the mechanism of the formation was investigated using batch tests with lake water and algae cultures.

  12. Brominated dioxins and dibenzofurans in human adipose tissue. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, P.H.; Stanley, J.S.; Bauer, K.; Ayling, R.E.; Thornburg, K.R.

    1990-04-11

    The report describes the analytical efforts for the determination of polybrominated dioxins (PBDDs) and furans (PBDFs) in human adipose tissues. Data on the precision and accuracy of the method for three tetra- through hexabrominated dioxins and three tetra- through hexabrominated furans (specific 2,3,7,8-substituted isomers) were generated from the analysis of 5 unspiked and 10 spiked (5 replicates at 2 spike levels) adipose tissue samples that were included with the analysis of the FY 1987 samples. In addition, data are presented on the results of the analysis of 48 composite samples for the six specific PBDD and PBDF compounds. The targeted 2,3,7,8-substituted PBDDs and PBDFs were not detected in any of the samples except those prepared as spiked QC materials. The detection limits calculated for the tetrabromo congeners in the samples ranged from 0.46 to 8.9 pg/g (lipid basis). The detection limits for the higher brominated congeners were typically greater than that observed for the tetrabrominated compounds. There is some evidence for the presence of other brominated compounds in the adipose tissue samples. Specifically, responses were noted that correspond to the qualitative criteria for polybrominated diphenyl ethers (hexa through octabromo).

  13. Comparative environmental analysis of waste brominated plastic thermal treatments

    International Nuclear Information System (INIS)

    The aim of this research activity is to investigate the environmental impact of different thermal treatments of waste electric and electronic equipment (WEEE), applying a life cycle assessment methodology. Two scenarios were assessed, which both allow the recovery of bromine: (A) the co-combustion of WEEE and green waste in a municipal solid waste combustion plant, and (B) the staged-gasification of WEEE and combustion of produced syngas in gas turbines. Mass and energy balances on the two scenarios were set and the analysis of the life cycle inventory and the life cycle impact assessment were conducted. Two impact assessment methods (Ecoindicator 99 and Impact 2002+) were slightly modified and then used with both scenarios. The results showed that scenario B (staged-gasification) had a potentially smaller environmental impact than scenario A (co-combustion). In particular, the thermal treatment of staged-gasification was more energy efficient than co-combustion, and therefore scenario B performed better than scenario A, mainly in the impact categories of 'fossil fuels' and 'climate change'. Moreover, the results showed that scenario B allows a higher recovery of bromine than scenario A; however, Br recovery leads to environmental benefits for both the scenarios. Finally the study demonstrates that WEEE thermal treatment for energy and matter recovery is an eco-efficient way to dispose of this kind of waste

  14. 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. PMID:26188404

  15. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Science.gov (United States)

    2010-04-01

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

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

    Science.gov (United States)

    Rebich, Theodore, Jr.; And Others

    1982-01-01

    Two types of school-based programs that increase students' use of fluoride for preventive dental health are described. In fluoride mouthrinse programs, teachers give their students a fluoride solution once a week in a paper cup. In areas where the level of fluoride in the water supply is insufficient, the flouride tablet program is used. (JN)

  17. Pulse radiolysis studies of the reactions of bromine atoms and dimethyl sulfoxide-bromine atom complexes with alcohols

    International Nuclear Information System (INIS)

    Dimethylsulfoxide (DMSO)-Br complexes were generated by pulse radiolysis of DMSO/bromomethane mixtures and the formation mechanism and spectral characteristics of the formed complexes were investigated in detail. The rate constant for the reaction of bromine atoms with DMSO and the extinction coefficient of the complex were obtained to be 4.6x109 M-1 s-1 and 6300 M-1 cm-1 at the absorption maximum of 430 nm. Rate constants for the reaction of bromine atoms with a series of alcohols were determined in CBrCl3 solutions applying a competitive kinetic method using the DMSO-Br complex as the reference system. The obtained rate constants were ∼108 M-1 s-1, one or two orders larger than those reported for highly polar solvents. Rate constants of DMSO-Br complexes with alcohols were determined to be ∼ 107 M-1 s-1. A comparison of the reactivities of Br atoms and DMSO-Br complexes with those of chlorine atoms and chlorine atom complexes which are ascribed to hydrogen abstracting reactants strongly indicates that hydrogen abstraction from alcohols is not the rate determining step in the case of Br atoms and DMSO-Br complexes

  18. Evaluation of toxic action of fluorides on agricultural plants

    Directory of Open Access Journals (Sweden)

    V. N. Grishko

    2007-03-01

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

  19. Fluoride

    Science.gov (United States)

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

  20. Effects of bromination on the viscoelastic response of vinyl ester nanocomposites

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Fire, smoke and toxicity are of significant concern for composite materials used in marine applications. Bromination of vinyl ester resin imparts fire retardancy as manifested by a reduction in the amount of smoke, carbon monoxide, and corrosive combustion products. In this research, the viscoelastic properties, modulus (stiffness and damping (energy dissipation, of 1.25 and 2.5 wt. percent nanoclay and exfoliated graphite nanoplatelet (xGnP reinforced non-brominated and brominated vinyl ester have been studied over a range of temperature and frequency. Effects of frequency on the viscoelastic behavior were investigated using a Dynamic Mechanical Analyzer (DMA by sweeping the frequency over three decades: 0.01, 0.1, 1 and 10 Hz, and temperature range from 30–150°C at a step rate of 4°C per minute. Master curves were generated by time-temperature superposing the experimental data at a reference temperature. The nano reinforced composites showed a drop in initial storage modulus with bromination. Nanocomposites with 1.25 and 2.5 wt. percent graphite had the highest storage modulus among brominated specimens. Bromination was also found to significantly increase the glass transition temperature (Tg and damping for all nanocomposites. Among the brominated specimens, 1.25 wt. Percent graphite platelet reinforced vinyl ester exhibited the best viscoelastic response with high damping and glass transition temperature, along with superior storage modulus over a longer time period.

  1. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Directory of Open Access Journals (Sweden)

    Richard Sauerheber

    2013-01-01

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

  2. Determination of bromide, chloride, fluoride, nitrate and sulphate by ion chromatography: comparisons of methodologies for rainfall, cloud water and river waters at the Plynlimon catchments of mid-Wales

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The results of determination of bromide, chloride, fluoride, nitrate and sulphate using ion chromatography (IC are compared with those obtained by colorimetric and inductively coupled plasma optical emission spectroscopy (ICPOES for rainfall, cloud water and stream waters in the Plynlimon experimental catchments of mid-Wales. For bromide, the concentrations determined by IC are lower than those for the colorimetric method used; the colorimetric method probably determined bromide plus organo-bromine compounds. It is suggested that the values determined by the colorimetric method be termed dissolved labile bromine (DLBr. The study shows that sulphate is the overriding form of sulphur in the waters. For chloride and nitrate, measurements by both methods approach a 1:1 relationship that is barely statistically significantly different from unity. For fluoride, the IC method gives lower values than the colorimetric, especially for the stream waters. However, the colorimetric method determines total fluorine so that a difference is to be expected (for example, fluoride strongly complexes with aluminium that is present, especially in the streamwater.

  3. The contribution of anthropogenic bromine emissions to past stratospheric ozone trends: a modelling study

    Directory of Open Access Journals (Sweden)

    B.-M. Sinnhuber

    2009-04-01

    Full Text Available Bromine compounds play an important role in the depletion of stratospheric ozone. We have calculated the changes in stratospheric ozone in response to changes in the halogen loading over the past decades, using a two-dimensional (latitude/height model constrained by source gas mixing ratios at the surface. Model calculations of the decrease of total column ozone since 1980 agree reasonably well with observed ozone trends, in particular when the contribution from very short-lived bromine compounds is included. Model calculations with bromine source gas mixing ratios fixed at 1959 levels, corresponding approximately to a situation with no anthropogenic bromine emissions, show an ozone column reduction between 1980 and 2005 at Northern Hemisphere mid-latitudes of only ≈55% compared to a model run including all halogen source gases. In this sense anthropogenic bromine emissions are responsible for ≈45% of the model estimated column ozone loss at Northern Hemisphere mid-latitudes. However, since a large fraction of the bromine induced ozone loss is due to the combined BrO/ClO catalytic cycle, the effect of bromine would have been smaller in the absence of anthropogenic chlorine emissions. The chemical efficiency of bromine relative to chlorine for global total ozone depletion from our model calculations, expressed by the so called α-factor, is 64 on an annual average. This value is much higher than previously published results. Updates in reaction rate constants can explain only part of the differences in α. The inclusion of bromine from very short-lived source gases has only a minor effect on the global mean α-factor.

  4. New Insight on the Response of Bacteria to Fluoride

    OpenAIRE

    Breaker, R R

    2012-01-01

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

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

    OpenAIRE

    Rošin-Grget, K.; Linčir, I.

    2001-01-01

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

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

    OpenAIRE

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

    2009-01-01

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

  7. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    OpenAIRE

    Richard Sauerheber

    2013-01-01

    The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity ...

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Oh, Taek-Keun; Saeki, Kazutoshi

    2009-01-01

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

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

    OpenAIRE

    Rajković Miloš B.; Novaković Ivana D.

    2007-01-01

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

  11. Enhancement of the carbon electrode capacitance by brominated hydroquinones

    Science.gov (United States)

    Gastol, Dominika; Walkowiak, Jedrzej; Fic, Krzysztof; Frackowiak, Elzbieta

    2016-09-01

    This paper presents supercapacitors utilizing new redox-active electrolytes with bromine species. Two sources of Br specimen were investigated, i.e. dibromodihydroxybenzene dissolved in KOH and potassium bromide dissolved in KOH with hydroxybenzene additive. KOH-activated carbon, exhibiting a well-developed porosity, was incorporated as an electrode material. The tested systems revealed a capacitance enhancement explained by Br- and partial BrO3- redox activity. The optimisation of the electrolyte concentration resulted in a capacitance value of 314 F g-1 achieved at 1.1 V voltage range. Good cyclability performance (11% capacitance loss) combined with a high capacitance value (244 F g-1) were obtained for the system operating in 0.2 mol L- 1 C6H4Br2O2 in 2 mol L-1 KOH electrolytic solution.

  12. Study of fluoride corrosion of nickel alloys

    Science.gov (United States)

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

    1969-01-01

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

  13. Recent advancements in fluoride: A systematic review

    OpenAIRE

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

    2015-01-01

    To review advancements of fluoride in dentistry, a search of 21 electronic databases and World Wide Web was conducted. Relevant journals were hand searched and further information was requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Fluoride has become an important tool in preventive dentistry. Current research is f...

  14. Fluoride removal from water by nano filtration

    International Nuclear Information System (INIS)

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

  15. Debating Water Fluoridation Before Dr. Strangelove.

    Science.gov (United States)

    Carstairs, Catherine

    2015-08-01

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

  16. Well Waters Fluoride in Enugu, Nigeria

    Directory of Open Access Journals (Sweden)

    EI Ugwuja

    2012-03-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

  18. Preparation and evaluation of composite membranes for zinc/bromine storage batteries

    Science.gov (United States)

    Arnold, Charles, Jr.; Assink, Roger A.

    Low coulombic efficiencies of zinc/bromine redox batteries were attributed to migration of bromine and negatively charged bromine moieties through the microporous separator used to separate the catholyte from the anolyte. While it was demonstrated that improvements in coulombic efficiency can be achieved by replacing the microporous separator with a cationic ion exchange membrane, these membranes are expensive and/or not sufficiently conductive to be practicable. It was found that the rate of bromine permeation can be reduced by two orders of magnitude with minimal decreases in conductivity by impregnating commercial microporous polyethylene type separators with sulfonated polysulfone, a cationic polyelectrolyte that was developed in earlier work for other redox storage batteries.

  19. A Novel Protocol for the Regioselective Bromination of Primary Alcohols in Unprotected Carbohydrates or Glycosides

    Institute of Scientific and Technical Information of China (English)

    薛伟华; 张立芬

    2012-01-01

    The regioselective and efficient bromination of primary hydroxyl groups in unprotected carbohydrates or glycosides is successfully achieved by using (chloro-phenylthio-methylene)dimethylammoniumchloride (CPMA) in the presence of tetrabutylammonium bromide (TBAB) in dry DMF.

  20. Evaluation of carbon cryogels used as cathodes for non-flowing zinc-bromine storage cells

    Energy Technology Data Exchange (ETDEWEB)

    Ayme-Perrot, David; Walter, Serge; Gabelica, Zelimir [Groupe Securite et Ecologie Chimiques (GSEC), ENSCMu, 3 rue Alfred Werner, F-68093 Mulhouse Cedex (France); Valange, Sabine [Laboratoire de Catalyse en Chimie Organique (LACCO), ESIP, 40 Avenue du Recteur Pineau, F-86022 Poitiers Cedex (France)

    2008-01-03

    Monolithic megaloporous carbon cryogels were examined for their potential applications as cathodic electrodes in secondary zinc-bromine cells. This work investigates the possibility of using their particular macroporous texture as microscopic bromine tanks in a zinc/bromine battery. The electrochemical behaviour of a cell based upon such a Br{sub 2} electrode was studied and discussed in terms of energy yields, energy storage capability and cycle life. Good storages (over 20 Wh kg{sup -1}) could be obtained during the first 2 h of cell charging for currents between 10 and 20 mA g{sup -1}. The energy yield remains almost constant during a fairly large number of cycles, basically for weak charges (e.g. 25 C g{sup -1}). Our findings show that the good cyclability of the cathodic electrode is a consequence of the liquid state of the active bromine phase. (author)

  1. Dynamic dielectric properties and the γ transition of bromine doped polyacrylonitrile

    Directory of Open Access Journals (Sweden)

    2007-10-01

    Full Text Available Based on monitoring the γ process (the lowest temperature-relaxation in polyacrylonitrile (PAN by dynamic dielectric spectroscopy, new evidence for the formation of a charge transfer complex between bromine dopants and nitrile groups is presented. The experimental work is carried out on PAN and nitrile polymerized PAN with and without bromine doping and the effects of these factors on the γ process are measured. Nitrile polymerization results in diminishing of the γ process and in a 15% increase in its activation energy, whereas bromine doping produces splitting of the original γ process in PAN – coupled with a significant activation energy increase – and its complete disappearance in nitrile polymerized PAN. Both the splitting of the γ process and the higher activation energy reflect bromine-nitrile adduct formation..

  2. Strand breaks in plasmid DNA, natural and brominated, by low-energy X-rays

    International Nuclear Information System (INIS)

    Single- and double-strand breaks were measured in Col E1 plasmid DNA, natural and partially brominated, irradiated with monoenergetic X-rays (from a synchrotron radiation source) on both sides of the K-absorption edge for Br. The fraction of the undamaged supercoiled form decreased exponentially with the photon dose; its yield in the brominated DNA did not exhibit any energy-dependence. This result is consistent with the calculated relative contributions of photoelectric interactions with individual component atoms which show that an electron flux originating in light atoms outweighs that from bromine. However, X-rays of energy above the Br K-edge appear slightly more efficient in producing double-strand breaks. This result seems to suggest that the positive charge and submolecular effects associated with the photo-absorption in bromine play some role in damaging processes, besides the initial distribution of deposited electron energy. (author)

  3. Bromine determination by neutron activation analysis and its distribution in the atmosphere

    International Nuclear Information System (INIS)

    Bromine, one of the main participants in ozone layer destruction, is 10 to 100 times more effective than chlorine. There are two principal sources of methyl bromide emissions: the oceans and some pesticides that are used in farming. Bromine was detected in 'premium' and 'magna sin' gasolines (2.86±0.96 and 1.54±0.38 ppm, respectively) as well as in condensed water found in exhaust pipes of vehicles. In addition, samples of rainwater were also analyzed to determine atmospheric bromine concentration. In water samples Br concentrations ranging from 2.09 to 0.06 ppm were found. The techniques utilised were neutron activation analysis and high voltage electrophoresis, the latter to determine the chemical form of bromine in condensed water samples. Finally, suspended particles from rainwater were also analysed by scanning electron microscopy (SEM). (author)

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

    OpenAIRE

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

    2013-01-01

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

  5. New insight into photo-bromination processes in saline surface waters: The case of salicylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tamtam, Fatima; Chiron, Serge, E-mail: serge.chiron@msem.univ-montp2.fr

    2012-10-01

    It was shown, through a combination of field and laboratory observations, that salicylic acid can undergo photo-bromination reactions in sunlit saline surface waters. Laboratory-scale experiments revealed that the photochemical yields of 5-bromosalicylic acid and 3,5-dibromosalicylic acid from salicylic acid were always low (in the 4% range at most). However, this might be of concern since these compounds are potential inhibitors of the 20{alpha}-hydroxysteroid dehydrogenase enzyme, with potential implications in endocrine disruption processes. At least two mechanisms were involved simultaneously to account for the photo-generation of brominated substances. The first one might involve the formation of reactive brominated radical species (Br{center_dot}, Br{sub 2}{center_dot}{sup -}) through hydroxyl radical mediated oxidation of bromide ions. These ions reacted more selectively than hydroxyl radicals with electron-rich organic pollutants such as salicylic acid. The second one might involve the formation of hypobromous acid, through a two electron oxidation of bromine ions by peroxynitrite. This reaction was catalyzed by nitrite, since these ions play a crucial role in the formation of nitric oxide upon photolysis. This nitric oxide further reacts with superoxide radical anions to yield peroxynitrite and by ammonium through the formation of N-bromoamines, probably due to the ability of N-bromoamines to promote the aromatic bromination of phenolic compounds. Field measurements revealed the presence of salicylic acid together with 5-bromosalicylic and 3,5-dibromosalicylic acid in a brackish coastal lagoon, thus confirming the environmental significance of the proposed photochemically induced bromination pathways. -- Highlights: Black-Right-Pointing-Pointer Brominated derivatives of salicylic acid were detected in a brackish lagoon. Black-Right-Pointing-Pointer A photochemical pathway was hypothesized to account for bromination of salicylic acid. Black

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

    International Nuclear Information System (INIS)

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

  7. Bromine as a Potential Threat to the Aquatic Environment in Areas of Mining Operations

    OpenAIRE

    Winid Bogumiła

    2013-01-01

    Fresh water normally contains limited quantities of bromine. The average content of bromine in the surface and groundwater active exchange zone generally does not exceed 200 μg/dm3 (0.2 mg/dm3). Mineralized waters, including some specific therapeutic waters, thermal waters, and brines, may contain bromides in amounts greater than in ordinary groundwater. Bromides will penetrate into groundwater and surface water due to salty groundwater inflow. In areas of mining operations, the management of...

  8. Complete Reductive Dehalogenation of Brominated Biphenyls by Anaerobic Microorganisms in Sediment

    OpenAIRE

    Bedard, Donna L.; Van Dort, Heidi M.

    1998-01-01

    We sought to determine whether microorganisms from the polychlorinated biphenyl (PCB)-contaminated sediment in Woods Pond (Lenox, Mass.) could dehalogenate brominated biphenyls. The PCB dechlorination specificities for the microorganisms in this sediment have been well characterized. This allowed us to compare the dehalogenation specificities for brominated biphenyls and chlorinated biphenyls within a single sediment. Anaerobic sediment microcosms were incubated separately at 25°C with 16 dif...

  9. Characterization and cyclic performance of membranes in hydrogen-bromine battery

    OpenAIRE

    Hugo, Yohanes

    2015-01-01

    A large renewable energy integration needs to be coupled with a low cost energy storage technology. One of the promising energy storage alternatives for the commercial market segment is the hydrogen bromine flow battery. Although the technology has been explored since 1980, the development of the hydrogen bromine flow battery system is still in the research phase due to the system complexity, the safety aspect, and technical problems. The literature review revealed that costs of the system an...

  10. Performance and Degradation of A Lithium-Bromine Rechargeable Fuel Cell Using Highly Concentrated Catholytes

    OpenAIRE

    Bai, Peng; Bazant, Martin Z.

    2016-01-01

    Lithium-air batteries have been considered as ultimate solutions for the power source of long-range electrified transportation, but state-of-the-art prototypes still suffer from short cycle life, low efficiency and poor power output. Here, a lithium-bromine rechargeable fuel cell using highly concentrated bromine catholytes is demonstrated with comparable specific energy, improved power density, and higher efficiency. The cell is similar in structure to a hybrid-electrolyte Li-air battery, wh...

  11. Bromine atom production and chain propagation during springtime Arctic ozone depletion events in Barrow, Alaska

    OpenAIRE

    Thompson, Chelsea R.; Shepson, Paul B.; Liao, Jin; Huey, L. Greg; Cantrell, Chris; Flocke, Frank; Orlando, John

    2016-01-01

    Ozone depletion events (ODEs) in the Arctic are primarily controlled by a bromine radical-catalyzed destruction mechanism that depends on the efficient production and recycling of Br atoms. Numerous laboratory and modeling studies have suggested the importance of heterogeneous recycling of Br through HOBr reaction with bromide on saline surfaces. However, the gas-phase regeneration of bromine atoms through BrO-BrO radical reactions has been assumed to be an efficient, if not dominant, pa...

  12. Gaia Paradigm: A Biotic Origin Of The Polar Sunrise Arctic Bromine Explosion

    OpenAIRE

    Iudin, M.

    2008-01-01

    The main attention is given to discussion of the natural causes and regularities of the Arctic bromine pollution. We make notice of marine microbial organisms and their metabolism as a prime driving force for the elemental biogeochemical cycles. One of the important conclusions of this study is on similarity between ocean bromine concentrating as by-product of the marine microbial activities and nitrogen fixation by soil bacteria. In both cases, microbial organisms and their food webs maintai...

  13. Springtime surface ozone fluctuations at high Arctic latitudes and their possible relationship to atmospheric bromine

    Science.gov (United States)

    Oltmans, Samuel J.; Sheridan, Patrick J.; Schnell, Russell C.; Winchester, John W.

    1988-01-01

    At high Arctic stations such as Barrow, Alaska, springtime near-surface ozone amounts fluctuate between the highest and lowest values seen during the course of the year. Episodes when the surface ozone concentration is essentially zero last up to several days during this time of year. In the Arctic Gas and Aerosol Sampling Program (AGASP-I and AGASP-II) in 1983 and 1986, it was found that ozone concentrations often showed a very steep gradient in altitude with very low values near the surface. The cold temperatures, and snow-covered ground make it unlikely that the surface itself would rapidly destroy significant amounts of ozone. The AGASP aircraft measurements that found low ozone concentrations in the lowest layers of the troposphere also found that filterable excess bromine (the amount of bromine in excess of the sea salt component) in samples collected wholly or partially beneath the temperature inversion had higher bromine concentrations than other tropospheric samples. Of the four lowest ozone minimum concentrations, three of them were associated with the highest bromine enrichments. Surface measurements of excess filterable bromine at Barrow show a strong seasonal dependence with values rising dramatically early in March, then declining in May. The concentration of organic bromine gases such as bromoform rise sharply during the winter and then begin to decline after March with winter and early spring values at least three times greater than the summer minimum.

  14. Addition of bromine as a diagnostic gas to inertial confinement fusion target microspheres

    International Nuclear Information System (INIS)

    Currently, direct fuel rho r measurements on Inertial Confinement Fusion (ICF) targets by neutron activation of the argon tracer gas mixed with the DT fuel would require a 100 fold increase in neutron yield. Bromine, on the other hand, has excellent properties for neutron activation analysis at neutron yields of 10two' to 108, when present at an internal pressure of from 0.1 to 0.2 atmospheres. Bromine addition is accomplished in a 2 furnace system using the dried-gel method of microsphere production. An upper furnace operated at 15000C is separated from a lower furnace by a cooled zone. The lower furnace is filled with bromine gas and operated at approximately 12500C. The upper furnace is the glass production furnace. The cooled zone in between the upper and lower furnace is to prevent the hot bromine gas from rising into the upper furnace. The microspheres pass through the cooled zone and immediately into the 12500C bromine furnace where the bromine permeates into the spheres

  15. Photothermally induced bromination of carbon/polymer bipolar plate materials for fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Martin; Franzka, Steffen [Fakultät für Chemie, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Carl-Benz-Straße 199, 47057 Duisburg (Germany); Cappuccio, Franco; Peinecke, Volker; Heinzel, Angelika [Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Carl-Benz-Straße 199, 47057 Duisburg (Germany); Zentrum für BrennstoffzellenTechnik (ZBT), Carl-Benz-Straße 201, 47057 Duisburg (Germany); Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Fakultät für Chemie, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Carl-Benz-Straße 199, 47057 Duisburg (Germany)

    2015-05-01

    Graphical abstract: - Highlights: • Photothermal laser bromination of carbon/polymer materials is demonstrated. • Using a microfocused laser functionalized domains with diameters of 5 μm and 100 μm and more can be fabricated. • Bromine groups can be transformed in a variety of other chemical functionalities, i.e. amine groups. • Depending on the chemical functionality, the local chemical affinity and wettability is changed. • The routine can be applied to standard bipolar plate materials used for fuel cell applications. - Abstract: A facile photothermal procedure for direct functionalization of carbon/polymer bipolar plate materials is demonstrated. Through irradiation with a microfocused beam of an Ar{sup +}-laser at λ = 514 nm in gaseous bromine and distinct laser powers and pulse lengths local bromination of the carbon/polymer material takes place. At a 1/e spot diameter of 2.1 μm, functionalized surface areas with diameters down to 5 μm are fabricated. In complementary experiments large-area bromination is investigated using an ordinary tungsten lamp. For characterization contact angle goniometry, X-ray photoelectron spectroscopy and electron microscopy in conjunction with labeling techniques are employed. After irradiation bromine groups can easily be substituted by other chemical functionalities, e.g. azide and amine groups. This provides a facile approach in order to fabricate surface patterns and gradient structures with varying wetting characteristics. Mechanistic aspects and prospects of photothermal routines in micropatterning of carbon/polymer materials are discussed.

  16. Photothermally induced bromination of carbon/polymer bipolar plate materials for fuel cell applications

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Photothermal laser bromination of carbon/polymer materials is demonstrated. • Using a microfocused laser functionalized domains with diameters of 5 μm and 100 μm and more can be fabricated. • Bromine groups can be transformed in a variety of other chemical functionalities, i.e. amine groups. • Depending on the chemical functionality, the local chemical affinity and wettability is changed. • The routine can be applied to standard bipolar plate materials used for fuel cell applications. - Abstract: A facile photothermal procedure for direct functionalization of carbon/polymer bipolar plate materials is demonstrated. Through irradiation with a microfocused beam of an Ar+-laser at λ = 514 nm in gaseous bromine and distinct laser powers and pulse lengths local bromination of the carbon/polymer material takes place. At a 1/e spot diameter of 2.1 μm, functionalized surface areas with diameters down to 5 μm are fabricated. In complementary experiments large-area bromination is investigated using an ordinary tungsten lamp. For characterization contact angle goniometry, X-ray photoelectron spectroscopy and electron microscopy in conjunction with labeling techniques are employed. After irradiation bromine groups can easily be substituted by other chemical functionalities, e.g. azide and amine groups. This provides a facile approach in order to fabricate surface patterns and gradient structures with varying wetting characteristics. Mechanistic aspects and prospects of photothermal routines in micropatterning of carbon/polymer materials are discussed

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

    Science.gov (United States)

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

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

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

    Science.gov (United States)

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

    2016-01-01

    With increased awareness of the health benefits of the compounds in green tea, especially polyphenols, its consumption is rising. The main purpose of this study is to determine the effect of different additives on the released fluoride into tea liquor and also daily fluoride intake. The concentrations of fluoride, nitrate, sulfate, and chloride were measured in 15 different flavored green teas (Refah-Lahijan). The fluoride and other anion concentrations were measured by ion chromatography method. The data were analyzed with Statistical Package for the Social Sciences version 16.0. The results showed that the minimum and maximum concentrations of fluoride in the green tea infusions were 0.162 mg/L (cinnamon-flavored green tea) and 3.29 mg/L (bagged peach-flavored green tea), respectively. The mean concentration of fluoride in the green tea leaves was 52 mg/kg, and approximately 89% of the fluoride was released from the green tea leaves into the infusions after brewing. The fluoride concentrations varied significantly among the examined green teas (P 0.05). Finally, drinking of the studied green teas cannot make a significant contribution to the daily dietary intake of F for consumers. PMID:27042093

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

    OpenAIRE

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

    2010-01-01

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

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

    Science.gov (United States)

    Talwar, Manjit; Tewari, Amrit; Chawla, H. S.; Sachdev, Vinod

    2016-01-01

    Objective: To assess the availability of fluoride concentration in saliva following the use of fluoride mouthrinse and dentifrice. Materials and Methods: The experiment was carried out in 7–15 year-old school children of Chandigarh (n = 90). The children were nonfluoride users. Baseline saliva samples were collected. The subjects were exposed to two test agents, i.e., fluoride mouthrinse (0.05%, 225 ppm F) and dentifrice (1000 ppm F) for 7 days and on the day 8, saliva samples were collected over a 20 hrs period. Wash out period of 31/2 months was there before the subjects were exposed to the second test agent. Fluoride in saliva was estimated using fluoride ion-specific electrode. Written informed consent was taken. Statistical Analysis: Kolmogorov–Smirnov test was applied to test the normality of the variables. Mann–Whitney U-test was used to compare the fluoride concentration available in saliva at respective time intervals subsequent to use of the two test agents. Results: Fluoride concentration was elevated in saliva compared to baseline for both the test agents. Fluoride mouthrinse (0.05% sodium fluoride [NaF]) and dentifrice (1000 ppm monofluorophosphate [MFP]) showed a biphasic clearance. Peak in saliva occurred at 15 mins postuse. Night-time use resulted in higher concentration of fluoride in saliva compared to baseline. There was statistically significantly higher fluoride concentration available in saliva for the dentifrice at 5 hrs, 10 hrs, and 20 hrs postuse (P < 0.05). Conclusion: Subsequent to the use of NaF (0.05%) daily mouthrinse and MFP dentifrice (1000 ppm) the fluoride concentration in saliva remained elevated to a level of 0.12 ppm for mouthrinse and 0.14 ppm for dentifrice compared to baseline (0.03 ppm) up to 20 hrs postuse. The therapeutic window though not yet established but suggested is 0.1–1 ppm for prevention of demineralization, indicating that daily use of fluoride mouthrinse and dentifrice provides fluoride concentration in

  1. Global Measurements of Atmospheric Sulfuryl Fluoride

    Science.gov (United States)

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

    2006-12-01

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

  2. Caries inhibition by fluoride-releasing primers.

    Science.gov (United States)

    Kerber, L J; Donly, K J

    1993-10-01

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

  3. Utilization of a Green Brominating Agent for the Spectrophotometric Determination of Pipazethate HCl in Pure Form and Pharmaceutical Preparations

    OpenAIRE

    Ayman A. Gouda

    2013-01-01

    Five simple, accurate, and sensitive spectrophotometric methods (A–E) have been described for the indirect assay of pipazethate HCl (PZT) either in pure form or in pharmaceutical preparations. The proposed methods are based on the bromination of pipazethate HCl with a solution of excess bromate-bromide mixture in hydrochloric acid medium and subsequent estimation of the residual bromine by different reaction schemes. In the first three methods (A–C), the determination of the residual bromine ...

  4. Thermodynamic data-base for metal fluorides

    International Nuclear Information System (INIS)

    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

  5. 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.

  6. 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. PMID:26574102

  7. The kinetics of fluoride uptake by synthetic hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Takudzwa Gomwe

    2012-03-01

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

  8. Removing Fluoride Ions with Continously Fed Activated Alumina.

    Science.gov (United States)

    Wu, Yeun C.; Itemaking, Isara Cholapranee

    1979-01-01

    Discussed is the mathematical basis for determining fluoride removal during water treatment with activated alumina. The study indicates that decreasing particle size decreases the pore diffusion effect and increases fluoride removal. (AS)

  9. Antimycobacterial brominated metabolites from two species of marine sponges.

    Science.gov (United States)

    de Oliveira, Maria Fernanda; de Oliveira, Jaine Honorata; Galetti, Fabio C; de Souza, Ana Olívia; Silva, Célio Lopes; Hajdu, Eduardo; Peixinho, Solange; Berlinck, Roberto G

    2006-04-01

    A screening of 500 crude extracts of marine invertebrates against the growth of Mycobacterium tuberculosis H37Rv yielded MeOH extracts of the sponges Aplysina cauliformis and Pachychalina sp. with significant activity. Further bioassay-guided fractionation of both crude extracts led to the isolation of four bromine-containing metabolites. The known (+)-fistularin-3 (1) and 11-deoxyfistularin-3 (2), and the new compound 2-(3-amino-2,4-dibromo-6-hydroxyphenyl)acetic acid (3) were isolated from the sponge A. cauliformis, while the new bromotyrosine-derived 3-(3,5-dibromo-4-methoxyphenyl)-2-methoxy- N-methylpropan-1-ammonium (4) was isolated from Pachychalina sp. Compound 4 exhibited weak antimycobacterial activity while compounds 1-3 displayed activity against Mycobacterium tuberculosis H37Rv, with MICs of 7.1, 7.3 and 49 microM, respectively. Compounds 1 and 2 also exhibited low cytotoxicity against J744 macrophages, indicating that both 1 and 2 are interesting leads for the development of new anti-tuberculosis agents. PMID:16557458

  10. Excited atomic bromine energy transfer and quenching mechanisms

    Science.gov (United States)

    Johnson, Ray O.

    1993-08-01

    Pulsed and steady-state photolysis experiments have been conducted to determine the rate coefficients for collisional deactivation of the spin-orbit excited state of atomic bromine, Br((sup 2)P(sub 1/2)). Pulsed lifetime studies for quenching by Br2 and CO2 established absolute rate coefficients at room temperature of k(sub Br2) = 1.2 +/- 0.1 x 10(exp-12) and k(sub CO2) = 1.5 +/0.2 x 10(exp-11) cu cm/molecule-s. Steady-state photolysis methods were used to determine the quenching rates for the rare gases, N2, 02, H2, D2, NO, NO2, N2O, SF6, CF4, CH4, CO, CO2, COS, SO2, H2S, HBr, HC1, and HI relative to that for Br2. Quenching rate temperature dependence was examined for Br2, CO2, N2O, HCl, COS, NO, and NO2 for temperatures from 300 to 420 K. Diffusion and three body effects were examined in order to determine the slowest relative quenching rate measurable by this experimental technique.

  11. Untypical bromine corrosion in boilers co-firing biomass

    Directory of Open Access Journals (Sweden)

    A. Hernas

    2012-09-01

    Full Text Available Purpose: The aim of this study was to determine the untypical corrosion resistance of rotary air preheaters in a biomass co-fired power plant.Design/methodology/approach: The selected results of some components of regenerative rotary air preheaters in a biomass co-fired power plant are presented. The macro and microstructure of corroded components of a LUVO preheater after 3 years of service are presented. The chemical composition of corrosion products was determined by X-ray microanalysis.Findings: Data concerning toxicity and identification of PBDEs (Polibrominated diphenyl ethers in the biomass is very limited. The presented research provides information and the proposed corrosion reaction mechanism in environments containing biomass with aggressive compounds like Cl, Si, H and Br.Research limitations/implications: An extended research on PBDEs in power plant fuels is necessary to give a full assessment of the corrosion mechanism in the presented environment; obligatory classification of the co-fired biomass.Originality/value: Firstly, an assessment of the danger for boiler materials co-firing biomass containing brominated organic flame and presentation of the reaction during the corrosion process and degradation of power boiler components in the presented environment. Secondly, the highlighting of the problem that there is a need to properly select and determine the chemical composition of the biomass used.

  12. Hydrogen cycle employing calcium-bromine and electrolysis

    International Nuclear Information System (INIS)

    The Secure Transportable Autonomous Reactor (STAR) project is part of the U.S. Department of Energy's (DOE's) Nuclear Energy Research Initiative (NERI) to develop Generation IV nuclear reactors that will supply high-temperature heat at over 800 C. The NERI project goal is to develop an economical, proliferation-resistant, sustainable, nuclear-based energy supply system based on a modular-sized fast reactor that is passively safe and cooled with heavy liquid metal. STAR consists of: (1) A combined thermochemical water-splitting cycle to generate hydrogen, (2) A steam turbine cycle to generate electricity, and (3) An optional capability to produce potable water from brackish or salt water. However, there has been limited reporting on critical elements of the thermochemical cycle: (1) establishing chemical reaction kinetics and operating pressures and (2) addressing materials issues for hydrogen production. This paper reviews the thermodynamic basis for a three-stage Calcium-Bromine water-splitting cycle based on the University of Tokyo Cycle No.3 [UT-3] and discusses the further chemistry work that is required to develop an economical process including modifying UT-3 to incorporate HBr dissociation

  13. Modelling chemistry over the Dead Sea: bromine and ozone chemistry

    Directory of Open Access Journals (Sweden)

    L. Smoydzin

    2009-02-01

    Full Text Available Measurements of O3 and BrO concentrations over the Dead Sea indicate that Ozone Depletion Events (ODEs, widely known to happen in polar regions, are also likely to occur over the Dead Sea due to the very high bromine content of the Dead Sea water. However, we show that BrO and O3 levels as they are detected cannot solely be explained by high Br levels in the Dead Sea water and the release of gas phase halogen species out of sea borne aerosol particles and their conversion to reactive halogen species. It is likely that other sources for reactive halogen compounds are needed to explain the observed concentrations for BrO and O3. To explain the chemical mechanism taking place over the Dead Sea leading to BrO levels of several pmol/mol we used the single column model MISTRA which calculates microphysics, meteorology, gas and aerosol phase chemistry. We performed pseudo Lagrangian studies by letting the model column first move over the desert which surrounds the Dead Sea region and then let it move over the Dead Sea itself. To include an additional source for gas phase halogen compounds, gas exchange between the Dead Sea water and the atmosphere is treated explicitly. Model calculations indicate that this process has to be included to explain the measurements.

  14. Modelling chemistry over the Dead Sea: bromine and ozone chemistry

    Directory of Open Access Journals (Sweden)

    R. von Glasow

    2009-07-01

    Full Text Available Measurements of O3 and BrO concentrations over the Dead Sea indicate that Ozone Depletion Events (ODEs, widely known to happen in polar regions, are also occuring over the Dead Sea due to the very high bromine content of the Dead Sea water. However, we show that BrO and O3 levels as they are detected cannot solely be explained by high Br levels in the Dead Sea water and the release of gas phase halogen species out of sea borne aerosol particles and their conversion to reactive halogen species. It is likely that other sources for reactive halogen compounds are needed to explain the observed concentrations for BrO and O3. To explain the chemical mechanism taking place over the Dead Sea leading to BrO levels of several pmol/mol we used the one-dimensional model MISTRA which calculates microphysics, meteorology, gas and aerosol phase chemistry. We performed pseudo Lagrangian studies by letting the model column first move over the desert which surrounds the Dead Sea region and then let it move over the Dead Sea itself. To include an additional source for gas phase halogen compounds, gas exchange between the Dead Sea water and the atmosphere is treated explicitly. Model calculations indicate that this process has to be included to explain the measurements.

  15. Non-polar halogenated natural products bioaccumulated in marine samples. II. Brominated and mixed halogenated compounds.

    Science.gov (United States)

    Vetter, Walter; Jun, Wu

    2003-07-01

    Several identified and potential natural brominated bioaccumulative compounds were studied in this work. 4,6-dibromo-2-(2('),4(')-dibromo)phenoxyanisole (BC-2) previously detected in Australian marine mammals and isolated from sponges, was synthesized. Two byproducts (a tetrabromo isomer and a tribromo congener) were investigated as well. The byproducts of the synthesis were not identified in the environmental samples investigated. Previously described natural brominated compounds (BC-1, BC-2, BC-3, BC-10, BC-11, MHC-1) and anthropogenic brominated diphenyl ethers (BDE-47, BDE-99, BDE-100, BDE-154) were detected in a sample of human milk. The sample was from a woman from the Faeroe Islands who frequently consumed fish as well as whale blubber and meat. The most abundant compound originated from the natural tetrabromo phenoxyanisole BC-3 which may have a 3:1 distribution of bromine on the two phenyl units. This sample also accumulated a dibromochloroanisole, as well as a previously unknown mixed halogenated compound (MHC-X) and an unknown, most likely aromatic brominated compound. Co-elutions on a DB-5 column were found for BDE-99 and BC-11 as well as BDE-154 and the unknown brominated compound. This suggests that quantification of these two compounds has to be carried out carefully.Two samples of lower trophic level, namely Baltic cod liver and Mexican mussel tissue, were investigated as well. The cod liver samples contained BDE congeners but also abundant signals for the natural 2,3,3('),4,4('),5,5(')-heptachloro-1(')-methyl-1,2(')-bipyrrole Q1 and tribromoanisole (TBA). The mussel sample contained Q1, TBA, another halogenated anisole, BC-1, BC-2, and BC-3, as well as additional, potential natural brominated compounds in the elution range of tribromophenoxyanisoles. PMID:12738265

  16. Impact of deep convection and dehydration on bromine loading in the upper troposphere and lower stratosphere

    Directory of Open Access Journals (Sweden)

    J. Aschmann

    2011-03-01

    Full Text Available Stratospheric bromine loading due to very short-lived substances is investigated with a three-dimensional chemical transport model over a period of 21 years using meteorological input data from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis from 1989 to the end of 2009. Within this framework we analyze the impact of dehydration and deep convection on the amount of stratospheric bromine using an idealized and a detailed full chemistry approach. We model the two most important brominated short-lived substances, bromoform (CHBr3 and dibromomethane (CH2Br2, assuming a uniform convective detrainment mixing ratio of 1 part per trillion by volume (pptv for both species. The contribution of very short-lived substances to stratospheric bromine varies drastically with the applied dehydration mechanism and the associated scavenging of soluble species ranging from 3.4 pptv in the idealized setup up to 5 pptv using the full chemistry scheme. In the latter case virtually the entire amount of bromine originating from very short-lived source gases is able to reach the stratosphere thus rendering the impact of dehydration and scavenging on inorganic bromine in the tropopause insignificant. Furthermore, our long-term calculations show that the mixing ratios of very short-lived substances are strongly correlated to convective activity, i.e. intensified convection leads to higher amounts of very short-lived substances in the upper troposphere/lower stratosphere especially under extreme conditions like El Niño seasons. However, this does not apply to the inorganic brominated product gases whose concentrations are anti-correlated to convective activity mainly due to convective dilution and possible scavenging, depending on the applied approach.

  17. Impact of deep convection and dehydration on bromine loading in the upper troposphere and lower stratosphere

    Directory of Open Access Journals (Sweden)

    J. Aschmann

    2011-01-01

    Full Text Available Stratospheric bromine loading due to very short-lived substances is investigated with a three-dimensional chemical transport model over a period of 21 years using meteorological input data from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis from 1989 to the end of 2009. Within this framework we analyze the impact of dehydration and deep convection on the amount of stratospheric bromine using an idealized and a detailed full chemistry approach. We model the two most important brominated short-lived substances, bromoform (CHBr3 and dibromomethane (CH2Br2, assuming a uniform detrainment mixing ratio of 1 part per trillion by volume (pptv for both species. The contribution of very short-lived substances to stratospheric bromine varies drastically with the applied dehydration mechanism and the associated scavenging of soluble species ranging from 3.4 pptv in the idealized setup up to 5 pptv using the full chemistry scheme. In the latter case virtually the entire amount of bromine originating from very short-lived source gases is able to reach the stratosphere thus rendering the impact of dehydration and scavenging on inorganic bromine in the tropopause insignificant. Furthermore, our long-term calculations show that the mixing ratios of very short-lived substances are strongly correlated to convective activity, i.e. intensified convection leads to higher amounts of very short-lived substances in the upper troposphere/lower stratosphere especially under extreme conditions like El Niño seasons. However, this does not apply to the inorganic brominated product gases whose concentrations are anti-correlated to convective activity mainly due to convective dilution and possible scavenging, depending on the applied approach.

  18. An exemplary case of a bromine explosion event linked to cyclone development in the Arctic

    Science.gov (United States)

    Blechschmidt, A.-M.; Richter, A.; Burrows, J. P.; Kaleschke, L.; Strong, K.; Theys, N.; Weber, M.; Zhao, X.; Zien, A.

    2016-02-01

    Intense, cyclone-like shaped plumes of tropospheric bromine monoxide (BrO) are regularly observed by GOME-2 on board the MetOp-A satellite over Arctic sea ice in polar spring. These plumes are often transported by high-latitude cyclones, sometimes over several days despite the short atmospheric lifetime of BrO. However, only few studies have focused on the role of polar weather systems in the development, duration and transport of tropospheric BrO plumes during bromine explosion events. The latter are caused by an autocatalytic chemical chain reaction associated with tropospheric ozone depletion and initiated by the release of bromine from cold brine-covered ice or snow to the atmosphere. In this manuscript, a case study investigating a comma-shaped BrO plume which developed over the Beaufort Sea and was observed by GOME-2 for several days is presented. By making combined use of satellite data and numerical models, it is shown that the occurrence of the plume was closely linked to frontal lifting in a polar cyclone and that it most likely resided in the lowest 3 km of the troposphere. In contrast to previous case studies, we demonstrate that the dry conveyor belt, a potentially bromine-rich stratospheric air stream which can complicate interpretation of satellite retrieved tropospheric BrO, is spatially separated from the observed BrO plume. It is concluded that weather conditions associated with the polar cyclone favoured the bromine activation cycle and blowing snow production, which may have acted as a bromine source during the bromine explosion event.

  19. Measurement-based modeling of bromine chemistry in the boundary layer: 1. Bromine chemistry at the Dead Sea

    Directory of Open Access Journals (Sweden)

    A. Pour Biazar

    2006-06-01

    Full Text Available The Dead Sea is an excellent natural laboratory for the investigation of Reactive Bromine Species (RBS chemistry, due to the high RBS levels observed in this area, combined with anthropogenic air pollutants up to several ppb. The present study investigated the chemical mechanism of RBS at the Dead Sea using a numerical one-dimensional chemical model. Simulations were based on data obtained from comprehensive measurements performed at sites along the Dead Sea. The simulations showed that the high BrO levels measured frequently at the Dead Sea could only partially be attributed to the highly concentrated Br− present in the Dead Sea water. Further, the RBS activity at the Dead Sea cannot solely be explained by a pure gas phase mechanism. This paper presents a chemical mechanism which can account for the observed chemical activity at the Dead Sea, with the addition of only two heterogeneous processes: the "Bromine Explosion" mechanism and the heterogeneous decomposition of BrONO2. Ozone frequently dropped below a threshold value of ~1 to 2 ppbv at the Dead Sea evaporation ponds, and in such cases, O3 became a limiting factor for the production of BrOx (BrO+Br. The entrainment of O3 fluxes into the evaporation ponds was found to be essential for the continuation of RBS activity, and to be the main reason for the positive correlation observed between BrO and O3 at low O3 concentrations, and for the jagged diurnal pattern of BrO observed in the Dead Sea area. The present study has shown that the heterogeneous decomposition of BrONO2 has the potential to greatly affect the RBS activity in areas under anthropogenic influence, mainly due to the positive correlation between the rate of this process and the levels of NO2. Further investigation of the influence of the decomposition of BrONO2 may be especially important in understanding the RBS activity at mid-latitudes.

  20. Measurement-based modeling of bromine chemistry in the boundary layer: 1. Bromine chemistry at the Dead Sea

    Directory of Open Access Journals (Sweden)

    E. Tas

    2006-01-01

    Full Text Available The Dead Sea is an excellent natural laboratory for the investigation of Reactive Bromine Species (RBS chemistry, due to the high RBS levels observed in this area, combined with anthropogenic air pollutants up to several ppb. The present study investigated the basic chemical mechanism of RBS at the Dead Sea using a numerical one-dimensional chemical model. Simulations were based on data obtained from comprehensive measurements performed at sites along the Dead Sea. The simulations showed that the high BrO levels measured frequently at the Dead Sea could only partially be attributed to the highly concentrated Br− present in the Dead Sea water. Furthermore, the RBS activity at the Dead Sea cannot solely be explained by a pure gas phase mechanism. This paper presents a chemical mechanism which can account for the observed chemical activity at the Dead Sea, with the addition of only two heterogeneous processes: the "Bromine Explosion" mechanism and the heterogeneous decomposition of BrONO2. Ozone frequently dropped below a threshold value of ~1 to 2 ppbv at the Dead Sea evaporation ponds, and in such cases, O3 became a limiting factor for the production of BrOx (BrO+Br. The entrainment of O3 fluxes into the evaporation ponds was found to be essential for the continuation of RBS activity, and to be the main reason for the jagged diurnal pattern of BrO observed in the Dead Sea area, and for the positive correlation observed between BrO and O3 at low O3 concentrations. The present study has shown that the heterogeneous decomposition of BrONO2 has a great potential to affect the RBS activity in areas influenced by anthropogenic emissions, mainly due to the positive correlation between the rate of this process and the levels of NO2. Further investigation of the influence of the decomposition of BrONO2 may be especially important in understanding the RBS activity at mid-latitudes.

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

    International Nuclear Information System (INIS)

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

  2. Parabens do not increase fluoride uptake by dental enamel

    OpenAIRE

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

    2010-01-01

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

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

    Science.gov (United States)

    Kanduti, Domen; Sterbenk, Petra; Artnik, Barbara

    2016-01-01

    Introduction: Appropriate oral health care is fundamental for any individual’s health. Dental caries is still one of the major public health problems. The most effective way of caries prevention is the use of fluoride. Aim: The aim of our research was to review the literature about fluoride toxicity and to inform physicians, dentists and public health specialists whether fluoride use is expedient and safe. Methods: Data we used in our review were systematically searched and collected from web pages and documents published from different international institutions. Results: Fluoride occurs naturally in our environment but we consume it in small amounts. Exposure can occur through dietary intake, respiration and fluoride supplements. The most important factor for fluoride presence in alimentation is fluoridated water. Methods, which led to greater fluoride exposure and lowered caries prevalence, are considered to be one of the greatest accomplishments in the 20th century`s public dental health. During pregnancy, the placenta acts as a barrier. The fluoride, therefore, crosses the placenta in low concentrations. Fluoride can be transmitted through the plasma into the mother’s milk; however, the concentration is low. The most important action of fluoride is topical, when it is present in the saliva in the appropriate concentration. The most important effect of fluoride on caries incidence is through its role in the process of remineralization and demineralization of tooth enamel. Acute toxicity can occur after ingesting one or more doses of fluoride over a short time period which then leads to poisoning. Today, poisoning is mainly due to unsupervised ingestion of products for dental and oral hygiene and over-fluoridated water. Conclusion: Even though fluoride can be toxic in extremely high concentrations, it`s topical use is safe. The European Academy of Paediatric Dentistry (EAPD) recommends a preventive topical use of fluoride supplements because of their

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

    Science.gov (United States)

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

    2014-09-01

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

  5. Preparation of uranium ingots from double fluorides

    International Nuclear Information System (INIS)

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

  6. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Vieira, A; Ruben, JL; Huysmans, MCDNJM

    2005-01-01

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

  8. 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...

  9. Cancer incidence and mortality in workers exposed to fluoride

    DEFF Research Database (Denmark)

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

    1992-01-01

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

  10. Coprecipitation of iron and silver with barium fluoride

    International Nuclear Information System (INIS)

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

  11. Plasma processing of fluoride solutions of refractory rare metals

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  12. Onderzoek naar de bepaling van fluoride in een doorstroomsysteem

    NARCIS (Netherlands)

    Neele J; Nagtegaal-Wouterse GWM; Reijnders HFR

    1989-01-01

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

  13. Synthesis of reagents for fluoride technologies

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  14. 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. PMID:26736058

  15. Brominated skeletal components of the marine demosponges, Aplysina cavernicola and Ianthella basta: analytical and biochemical investigations.

    Science.gov (United States)

    Kunze, Kurt; Niemann, Hendrik; Ueberlein, Susanne; Schulze, Renate; Ehrlich, Hermann; Brunner, Eike; Proksch, Peter; van Pée, Karl-Heinz

    2013-04-01

    Demosponges possess a skeleton made of a composite material with various organic constituents and/or siliceous spicules. Chitin is an integral part of the skeleton of different sponges of the order Verongida. Moreover, sponges of the order Verongida, such as Aplysina cavernicola or Ianthella basta, are well-known for the biosynthesis of brominated tyrosine derivates, characteristic bioactive natural products. It has been unknown so far whether these compounds are exclusively present in the cellular matrix or whether they may also be incorporated into the chitin-based skeletons. In the present study, we therefore examined the skeletons of A. cavernicola and I. basta with respect to the presence of bromotyrosine metabolites. The chitin-based-skeletons isolated from these sponges indeed contain significant amounts of brominated compounds, which are not easily extractable from the skeletons by common solvents, such as MeOH, as shown by HPLC analyses in combination with NMR and IR spectroscopic measurements. Quantitative potentiometric analyses confirm that the skeleton-associated bromine mainly withstands the MeOH-based extraction. This observation suggests that the respective, but yet unidentified, brominated compounds are strongly bound to the sponge skeletons, possibly by covalent bonding. Moreover, gene fragments of halogenases suggested to be responsible for the incorporation of bromine into organic molecules could be amplified from DNA isolated from sponge samples enriched for sponge-associated bacteria. PMID:23595055

  16. Removal of brominated flame retardant from electrical and electronic waste plastic by solvothermal technique

    International Nuclear Information System (INIS)

    Highlights: ► A process for brominated flame retardants (BFRs) removal in plastic was established. ► The plastic became bromine-free with the structure maintained after this treatment. ► BFRs transferred into alcohol solvent were easily debrominated by metallic copper. - Abstract: Brominated flame retardants (BFRs) in electrical and electronic (E and E) waste plastic are toxic, bioaccumulative and recalcitrant. In the present study, tetrabromobisphenol A (TBBPA) contained in this type of plastic was tentatively subjected to solvothermal treatment so as to obtain bromine-free plastic. Methanol, ethanol and isopropanol were examined as solvents for solvothermal treatment and it was found that methanol was the optimal solvent for TBBPA removal. The optimum temperature, time and liquid to solid ratio for solvothermal treatment to remove TBBPA were 90 °C, 2 h and 15:1, respectively. After the treatment with various alcohol solvents, it was found that TBBPA was finally transferred into the solvents and bromine in the extract was debrominated catalyzed by metallic copper. Bisphenol A and cuprous bromide were the main products after debromination. The morphology and FTIR properties of the plastic were generally unchanged after the solvothermal treatment indicating that the structure of the plastic maintained after the process. This work provides a clean and applicable process for BFRs-containing plastic disposal.

  17. Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

    Science.gov (United States)

    Baldwin, Richard S.

    1987-01-01

    The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

  18. The bromine enhancement ratio in mammalian cells in vitro and experimental mouse tumours

    International Nuclear Information System (INIS)

    Human kidney cells in culture and cells of mouse sarcoma-180 were allowed to incorporate bromine into their DNA. Cultured cells with and without incorporated BUdR were irradiated with electromagnetic radiations ranging in energy from 12 keV X-rays to 60Co γ-rays to find out whether or not there exists any energy dependence of the bromine dose enhancement ratio BER. Such a dependence should show in the immediate neighbourhood of the K-absorption edge of bromine (13.5 keV). Any influence of the Auger effect triggered in bromine by external irradiation should show by a significant increase of the BER for energies rising from slightly below to slight above the bromine K-edge. Values of D37, D0 and the extrapolation numbers of the cell survival curves served as biological endpoints. Measured values of BER ranged from 1.12-2.00 without any significant dependence on energy. A weakly pronounced peak was found for 50 kV X-rays of 26 keV mean energy. Sarcoma-180 were irradiated with 14 keV X-rays and 60C γ-rays. BUdR was administered i.v., i.p. and directly into the tumours in quantities of up to 1 ml of a 10-3M solution. (Auth.)

  19. Bromine and bromide content in soils: Analytical approach from total reflection X-ray fluorescence spectrometry.

    Science.gov (United States)

    Gallardo, Helena; Queralt, Ignasi; Tapias, Josefina; Candela, Lucila; Margui, Eva

    2016-08-01

    Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water. PMID:27179429

  20. Brominated Skeletal Components of the Marine Demosponges, Aplysina cavernicola and Ianthella basta: Analytical and Biochemical Investigations

    Directory of Open Access Journals (Sweden)

    Eike Brunner

    2013-04-01

    Full Text Available Demosponges possess a skeleton made of a composite material with various organic constituents and/or siliceous spicules. Chitin is an integral part of the skeleton of different sponges of the order Verongida. Moreover, sponges of the order Verongida, such as Aplysina cavernicola or Ianthella basta, are well-known for the biosynthesis of brominated tyrosine derivates, characteristic bioactive natural products. It has been unknown so far whether these compounds are exclusively present in the cellular matrix or whether they may also be incorporated into the chitin-based skeletons. In the present study, we therefore examined the skeletons of A. cavernicola and I. basta with respect to the presence of bromotyrosine metabolites. The chitin-based-skeletons isolated from these sponges indeed contain significant amounts of brominated compounds, which are not easily extractable from the skeletons by common solvents, such as MeOH, as shown by HPLC analyses in combination with NMR and IR spectroscopic measurements. Quantitative potentiometric analyses confirm that the skeleton-associated bromine mainly withstands the MeOH-based extraction. This observation suggests that the respective, but yet unidentified, brominated compounds are strongly bound to the sponge skeletons, possibly by covalent bonding. Moreover, gene fragments of halogenases suggested to be responsible for the incorporation of bromine into organic molecules could be amplified from DNA isolated from sponge samples enriched for sponge-associated bacteria.

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

    OpenAIRE

    Roy J; Rane S; Ghani A; Chaudhury C

    1993-01-01

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

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

    Science.gov (United States)

    Imtani, Ali Nasir

    2012-01-01

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

  3. 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.

  4. Human health risk associated with brominated flame-retardants (BFRs).

    Science.gov (United States)

    Lyche, Jan L; Rosseland, Carola; Berge, Gunnar; Polder, Anuschka

    2015-01-01

    The purposes of this review are to assess the human exposure and human and experimental evidence for adverse effects of brominated flame-retardants (BFRs) with specific focus on intake from seafood. The leakage of BFRs from consumer products leads to exposure of humans from fetal life to adulthood. Fish and fish products contain the highest levels of BFRs and dominate the dietary intake of frequent fish eaters in Europe, while meat, followed by seafood and dairy products accounted for the highest US dietary intake. House dust is also reported as an important source of exposure for children as well as adults. The levels of BFRs in the general North American populations are higher than those in Europe and Japan and the highest levels are detected in infants and toddlers. The daily intake via breast milk exceeds the RfD in 10% of US infants. BFRs including PBDEs, HBCDs and TBBP-A have induced endocrine-, reproductive- and behavior effects in laboratory animals. Furthermore, recent human epidemiological data demonstrated association between exposure to BFRs and similar adverse effects as observed in animal studies. Fish including farmed fish and crude fish oil for human consumption may contain substantial levels of BFRs and infants and toddlers consuming these products on a daily basis may exceed the tolerable daily intake suggesting that fish and fish oil alone represent a risk to human health. This intake comes in addition to exposure from other sources (breast milk, other food, house dust). Because potential harmful concentrations of BFRs and other toxicants occur in fish and fish products, research on a wider range of products is warranted, to assess health hazard related to the contamination of fish and fish products for human consumption. PMID:25454234

  5. Manufacture of high purity low arsenic anhydrous hydrogen fluoride

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Follin-Arbelet, Benoit; Moum, Bjørn

    2016-09-01

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

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

    OpenAIRE

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

    1987-01-01

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

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

    OpenAIRE

    Vitoria I

    2015-01-01

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

  9. Determination of bromine contents in blood and hair of workers exposed to methyl by radioactivation analysis method bromide

    International Nuclear Information System (INIS)

    The bromine contained in blood and hair samples obtained from workers exposed to methyl bromide was analyzed by nondestructive activation analysis. The samples were irradiated for 1 min in pneumatic irradiation facility of Kyoto University research reactor with an estimated thermal neutron flux density at 2 x 1013 n.cm-2.sec-1. The irradiation was counted with Ge(Li) detector. The duration of measurement of radionuclide bromine in blood and hair was 200 sec within 2 - 10 min after irradiation. The bromine content of serum sample obtained from a worker suspected of methyl bromide poisoning was found to be 412 μg/g on 13 days apart from exposure to methyl bromide. The biological half-life of bromine in this case was found to be about 16 days. Then bromine contents in serum and hair samples obtained from workers exposed to methyl bromide were found to be 1.7 and 2.6 times higher respectively than those of nonexposed workers. Any correlations of bromine contents were not observed between serum and hair samples obtained from workers exposed to methyl bromide, nor between bromine amount in the serum of workers exposed to methyl bromide and the terms exposed to it, but statistically significant positive correlation was observed between bromine amount in the hair of workers exposed to methyl bromide and the terms exposed to it. (author)

  10. Actinide measurements by AMS using fluoride matrices

    Science.gov (United States)

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

    2015-10-01

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

  11. THE DEVELOPMENT OF AN INDIGENOUS FLUORIDE FILTER

    Science.gov (United States)

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

  12. Bromine-77-labeled estrogen receptor-binding radiopharmaceuticals for breast tumor imaging

    International Nuclear Information System (INIS)

    Two derivatives of 16α-bromoestradiol, both with and without an 11β-methoxy substituent, have been labeled with bromine-77 and evaluated as potential breast tumor imaging agents. Extensive characterization of these radiotracers in animal models has demonstrated their effective concentration in estrogen target tissues. Preliminary clinical studies have demonstrated the potential of radiolabeled estrogens for breast tumor imaging; however, the suboptimal decay properties of bromine-77 limit the utility of these agents in imaging studies. These results with 77-Br-labeled estrogens suggest that estrogen derivatives labeled with other radionuclides should provide enhanced image resolution with various imaging devices. Although the decay characteristics of bromine-77 are such that it is not ideally suited to imaging with conventional gamma cameras, it may be a useful radionuclide for therapeutic applications

  13. Determination by neutron activation analysis of loss of arsenic, antimony, bromine and mercury during lyophilization

    International Nuclear Information System (INIS)

    Neutron activation analysis has been used to monitor the loss of arsenic, as dimethylarsinic acid, (CH3)2AsOOH, or as sodium arsenate (Na2HAsO4.7H2O), antimony (as potassium antimony, tartrate, KSbC4O7.1/2H2O) and bromine (as bromide ion) during lyophilization of acidified and neutral aqueous synthetic and environmental samples. Losses of Sb and As ranged from zero to 60%, while losses of bromine were constant (at 91%) in acidic solutions. The variable losses of As and Sb were due solely to the presence of and partial decomposition of the (CH3)2AsOOH. Electrochemical oxidation of Br- to Br2 is responsible for the high losses of bromine. In addition losses of mercury (as methylmercuric chloride) were 1O0% in both acidic and neutral aqueous synthetic samples during lyophilization. (author)

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

    Science.gov (United States)

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

    2015-01-01

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

  15. 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.

  16. Estimation of atmospheric fluoride by limed filter papers

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Msonda, K. W. M.; Masamba, W. R. L.; Fabiano, E.

    A study was carried out to determine fluoride concentration in groundwaters of Nathenje area situated in Lilongwe District in the central region of Malawi. Water samples were collected from 176 boreholes and shallow wells during different months in 2001 and 2002. Samples were then analysed for fluoride by using a fluoride electrode and an ion selective meter. The results showed that fluoride concentrations for the rainy season varied from part of Nathenje had high fluoride concentration of between 2 and 7.02 mg/l and these high fluoride values seemed to extend eastwards beyond the boundary of the study area. However, the southern and western parts had dental fluorosis in areas where the fluoride concentration was high.

  18. 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. PMID:27086437

  19. Regional variation and possible sources of brominated contaminants in breast milk from Japan

    International Nuclear Information System (INIS)

    This study focuses on the regional trends and possible sources of brominated organic contaminants accumulated in breast milk from mothers in southeastern (Okinawa) and northwestern (Hokkaido) areas of Japan. For persistent brominated flame retardants, polybrominated diphenyl ethers (PBDEs; major components, BDE-47 and BDE-153) were distributed at higher levels in mothers from Okinawa (mean, 2.1 ng/g lipid), while hexabromobenzene (HeBB) and its metabolite 1,2,4,5-tetrabromobenzene were more abundantly detected in mothers from Hokkaido (0.86 and 2.6 ng/g lipid), suggesting that there are regional differences in their exposure in Japan. We also detected naturally produced brominated compounds, one of which was identified as 2′-methoxy-2,3′,4,5′-tetrabromodiphenyl ether (2′-MeO-BDE68) at higher levels in mothers from Okinawa (0.39 ng/g lipid), while the other was identified as 3,3′,4,4′-tetrabromo-5,5′-dichloro-2,2′-dimethyl-1,1′-bipyrrole in mothers from Hokkaido (0.45 ng/g lipid). The regional variation may be caused by source differences, i.e. southern seafood for MeO-PBDEs and northern biota for halogenated bipyrroles in the Japanese coastal water. - Highlights: ► In this study, we detected brominated organic contaminants in Japanese breast milk. ► Naturally produced brominated organic contaminants were also detected. ► Northern and southern Japan showed regional differences in these contaminants. ► Exposure to the contaminants is suggested to arise from different specific sources. - Brominated organic contaminants were detected in Japanese breast milk.

  20. 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.

  1. 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.

  2. Dichlorinated and Brominated Rugulovasines, Ergot Alkaloids Produced by Talaromyces wortmannii

    DEFF Research Database (Denmark)

    Soman De Medeiros, Lívia; da Silva, José Vinícius; Abreu, Lucas Magalhães;

    2015-01-01

    . Brominated rugulovasines were also detected when the microbial incubation medium was supplemented with bromine sources. Studies from 1D/2D NMR and HRMS spectroscopy data allowed the structural elucidation of the dichlorinated compounds, while tandem MS/HRMS data analysis supported the rationalization of......UHPLC-DAD-HRMS based dereplication guided the detection of new halogenated alkaloids co-produced by Talaromyces wortmannii. From the fungal growth in large scale, the epimers 2,8-dichlororugulovasines A and B were purified and further identified by means of a HPLC-SPE/NMR hyphenated system...

  3. Photochemical bromination of substituted indan-1-one derivatives: synthesis of new polybromoindan-1-one derivatives

    OpenAIRE

    KUŞ, Nermin Şimşek

    2009-01-01

    The photobromination of substituted indan derivatives was studied. Four products, 2,3-dibromo-inden-1-one (5), trans-2,3-dibromoindan-1-one (6), 2,2-dibromoindan-1,3-dione (7) and 2,2-dibromoindan-1-one (8), were obtained by the bromination of indan-1-one (4). The bromination of 2-methyl indanone (9) and 3-methyl-indanone (13) gave the corresponding monobromo, dibromo, and tribromo compounds in high yield. 4-Nitro indan (16) was tribrominated under same condition reaction. The stru...

  4. Effect of Brominated Furanones on the Formation of Biofilm by Escherichia coli on Polyvinyl Chloride Materials

    OpenAIRE

    Lianhua, Ye; Yunchao, Huang; Geng, Xu; Youquang, Zhou; Guangqiang, Zhao; Yujie, Lei

    2013-01-01

    To study the influence of brominated furanones on the biofilm (BF) formation by Escherichia coli (E. coli) on polyvinyl chloride (PVC) material, and to provide new ways of surface modification of materials to clinically prevent biomaterial centered infection. Three brominated furanones, dissolved in ethanol, furanone-1(3,4-dibromo-5-hydroxyl-furanone), furanone-2(4-bromo-5-(4-methoxypheny)-3-(methylamino)-furanone), and furanone-3(3,4-dibromo-5,5-dimethoxypheny-2(5H)-furanone) with representa...

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Stephen Peckham

    2014-01-01

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

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

    DEFF Research Database (Denmark)

    Petersen, Poul Erik; Lennon, Michael A

    2004-01-01

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

  8. Fluoride content of clay minerals and argillaceous earth materials

    Science.gov (United States)

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

    1977-01-01

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

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

    Science.gov (United States)

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

    2007-09-01

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

  10. 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.

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

    OpenAIRE

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

    1984-01-01

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

  12. Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

    OpenAIRE

    Han Wang; Kun Wen; Nurbiya Nurahmat; Yan Shao; He Zhang; Chao Wei; Ya Li; Yongjia Shen; Zhihua Sun

    2012-01-01

    By using ionic liquids as solvents, the chlorination or bromination of unprotected anilines at the para-position can be achieved in high yields with copper halides under mild conditions, without the need for potentially hazardous operations such as supplementing oxygen or gaseous HCl.

  13. Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

    Directory of Open Access Journals (Sweden)

    Han Wang

    2012-05-01

    Full Text Available By using ionic liquids as solvents, the chlorination or bromination of unprotected anilines at the para-position can be achieved in high yields with copper halides under mild conditions, without the need for potentially hazardous operations such as supplementing oxygen or gaseous HCl.

  14. Kinetics of aerobic cometabolic biodegradation of chlorinated and brominated aliphatic hydrocarbons: A review.

    Science.gov (United States)

    Jesus, João; Frascari, Dario; Pozdniakova, Tatiana; Danko, Anthony S

    2016-05-15

    This review analyses kinetic studies of aerobic cometabolism (AC) of halogenated aliphatic hydrocarbons (HAHs) from 2001-2015 in order to (i) compare the different kinetic models proposed, (ii) analyse the estimated model parameters with a focus on novel HAHs and the identification of general trends, and (iii) identify further research needs. The results of this analysis show that aerobic cometabolism can degrade a wide range of HAHs, including HAHs that were not previously tested such as chlorinated propanes, highly chlorinated ethanes and brominated methanes and ethanes. The degree of chlorine mineralization was very high for the chlorinated HAHs. Bromine mineralization was not determined for studies with brominated aliphatics. The examined research period led to the identification of novel growth substrates of potentially high interest. Decreasing performance of aerobic cometabolism were found with increasing chlorination, indicating the high potential of aerobic cometabolism in the presence of medium- and low-halogenated HAHs. Further research is needed for the AC of brominated aliphatic hydrocarbons, the potential for biofilm aerobic cometabolism processes, HAH-HAH mutual inhibition and the identification of the enzymes responsible for each aerobic cometabolism process. Lastly, some indications for a possible standardization of future kinetic studies of HAH aerobic cometabolism are provided. PMID:26874310

  15. Performance and Degradation of A Lithium-Bromine Rechargeable Fuel Cell Using Highly Concentrated Catholytes

    CERN Document Server

    Bai, Peng

    2016-01-01

    Lithium-air batteries have been considered as ultimate solutions for the power source of long-range electrified transportation, but state-of-the-art prototypes still suffer from short cycle life, low efficiency and poor power output. Here, a lithium-bromine rechargeable fuel cell using highly concentrated bromine catholytes is demonstrated with comparable specific energy, improved power density, and higher efficiency. The cell is similar in structure to a hybrid-electrolyte Li-air battery, where a lithium metal anode in nonaqueous electrolyte is separated from aqueous bromine catholytes by a lithium-ion conducting ceramic plate. The cell with a flat graphite electrode can discharge at a peak power density around 9mW cm-2 and in principle could provide a specific energy of 791.8 Wh kg-1, superior to most existing cathode materials and catholytes. It can also run in regenerative mode to recover the lithium metal anode and free bromine with 80-90% voltage efficiency, without any catalysts. Degradation of the sol...

  16. On the bromination of the dihydroazulene/vinylheptafulvene photo-/thermoswitch

    DEFF Research Database (Denmark)

    Mazzanti, Virginia; Cacciarini, Martina; Broman, Søren Lindbæk;

    2012-01-01

    Background: The dihydroazulene (DHA)/vinylheptafulvene (VHF) system (with two cyano groups at C1) functions as a photo-/thermoswitch. Direct ionic bromination of DHA has previously furnished a regioselective route to a 7,8-dibromide, which by elimination was converted to a 7-bromo-substituted DHA...

  17. Photothermally induced bromination of carbon/polymer bipolar plate materials for fuel cell applications

    Science.gov (United States)

    Schade, Martin; Franzka, Steffen; Cappuccio, Franco; Peinecke, Volker; Heinzel, Angelika; Hartmann, Nils

    2015-05-01

    A facile photothermal procedure for direct functionalization of carbon/polymer bipolar plate materials is demonstrated. Through irradiation with a microfocused beam of an Ar+-laser at λ = 514 nm in gaseous bromine and distinct laser powers and pulse lengths local bromination of the carbon/polymer material takes place. At a 1/e spot diameter of 2.1 μm, functionalized surface areas with diameters down to 5 μm are fabricated. In complementary experiments large-area bromination is investigated using an ordinary tungsten lamp. For characterization contact angle goniometry, X-ray photoelectron spectroscopy and electron microscopy in conjunction with labeling techniques are employed. After irradiation bromine groups can easily be substituted by other chemical functionalities, e.g. azide and amine groups. This provides a facile approach in order to fabricate surface patterns and gradient structures with varying wetting characteristics. Mechanistic aspects and prospects of photothermal routines in micropatterning of carbon/polymer materials are discussed.

  18. Bromine-82 Labelling of Human Serum Albumin, Insulin and Fibrinogen by Electrochemical Means

    International Nuclear Information System (INIS)

    The authors describe results obtained with a method using bromine-82 to label human serum albumin, fibrinogen and insulin, three organic substances of special importance in diagnostics and biological research. The method involves electrolytic bromination in an aqueous solution; this is performed in an electrolysis cell, whose anodic zone containing the substance to be labelled is partitioned from the cathodic zone by a dialysis membrane. For each of the three substances mentioned, the degree of bromination produced by a direct current (200, 200, 300 x 10-6 Å) was studied as a function of anode potential in 10-3 and 10-4 M solutions of NH4Br, the amount of bromine-labelled substance formed being checked by radio electrophoresis for various anodic potential values differing from each other by 50 mV. By immuno- electrophoresis it was ascertained that denaturation of albumin and fibrinogen only starts at anodic potential values for which the degree of labelling is already very high as compared with that yielded by chemical methods of labelling. The method here described has the advantage of rapid execution and is well suited to remote handling in a shielded zone. (author)

  19. Microbial degradation of the brominated flame retardant TBNPA by groundwater bacteria: laboratory and field study.

    Science.gov (United States)

    Balaban, Noa; Bernstein, Anat; Gelman, Faina; Ronen, Zeev

    2016-08-01

    In the present study, the biodegradation of the brominated flame retardant tribromoneopentylalcohol (TBNPA) by a groundwater enrichment culture was investigated using a dual carbon ((13)C/(12)C)- bromine ((81)Br/(79)Br) stable isotope analysis. An indigenous aerobic bacterial consortium was enriched from the polluted groundwater underlying an industrial site in the northern Negev Desert, Israel, where TBNPA is an abundant pollutant. Aerobic biodegradation was shown to be rapid, with complete debromination within a few days, whereas anaerobic biodegradation was not observed. Biodegradation under aerobic conditions was accompanied by a significant carbon isotope effect with an isotopic enrichment factor of ɛCbulk = -8.8‰ ± 1.5‰, without any detectable bromine isotope fractionation. It was found that molecular oxygen is necessary for biodegradation to occur, suggesting an initial oxidative step. Based on these results, it was proposed that H abstraction from the C-H bond is the first step of TBNPA biodegradation under aerobic conditions, and that the C-H bond cleavage results in the formation of unstable intermediates, which are rapidly debrominated. A preliminary isotopic analysis of TBNPA in the groundwater underlying the industrial area revealed that there are no changes in the carbon and bromine isotope ratio values downstream of the contamination source. Considering that anoxic conditions prevail in the groundwater of the contaminated site, the lack of isotope shifts in TBNPA indicates the lack of TBNPA biodegradation in the groundwater, in accordance with our findings. PMID:27183339

  20. Electron stimulated desorption of anions from native and brominated single stranded oligonucleotide trimers

    Energy Technology Data Exchange (ETDEWEB)

    Polska, Katarzyna; Rak, Janusz [Department of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Bass, Andrew D.; Cloutier, Pierre; Sanche, Leon [Research Group in the Radiation Sciences, Faculty of Medicine, Universite de Sherbrooke, Sherbrooke, Quebec J1H 5N4 (Canada)

    2012-02-21

    We measured the low energy electron stimulated desorption (ESD) of anions from thin films of native (TXT) and bromine monosubstituted (TBrXT) oligonucleotide trimers deposited on a gold surface (T = thymidine, X = T, deoxycytidine (C), deoxyadenosine (A) or deoxyguanosine (G), Br = bromine). The desorption of H{sup -}, CH{sub 3}{sup -}/NH{sup -}, O{sup -}/NH{sub 2}{sup -}, OH{sup -}, CN{sup -}, and Br{sup -} was induced by 0 to 20 eV electrons. Dissociative electron attachment, below 12 eV, and dipolar dissociation, above 12 eV, are responsible for the formation of these anions. The comparison of the results obtained for the native and brominated trimers suggests that the main pathways of TBrXT degradation correspond to the release of the hydride and bromide anions. Significantly, the presence of bromine in oligonucleotide trimers blocks the electron-induced degradation of nuclobases as evidenced by a dramatic decrease in CN{sup -} desorption. An increase in the yields of OH{sup -} is also observed. The debromination yield of particular oligonucleotides diminishes in the following order: BrdU > BrdA > BrdG > BrdC. Based on these results, 5-bromo-2{sup '}-deoxyuridine appears to be the best radiosensitizer among the studied bromonucleosides.

  1. Assessment of the zinc-bromine battery for utility load leveling. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Will, F. G.; Iacovangelo, C. D.; Jackowski, J. S.; Secor, F. W.

    1978-03-15

    The technical and economic prospects of zinc-bromine batteries employing Nafion/sup R*/ fluorinated ion exchange membranes was evaluated. The applicability and performance limits of a variety of materials and concepts were explored, noval all-carbon electrode structures developed and tested in cells of up to 36 w-hr size, and a system design and cost analysis was performed.

  2. Biodegradation of brominated aromatics by cultures and laccase of Trametes versicolor

    Czech Academy of Sciences Publication Activity Database

    Uhnáková, Bronislava; Petříčková, Alena; Biedermann, David; Homolka, Ladislav; Vejvoda, Vojtěch; Bednář, P.; Papoušková, B.; Šulc, Miroslav; Martínková, Ludmila

    2009-01-01

    Roč. 76, č. 6 (2009), s. 826-832. ISSN 0045-6535 R&D Projects: GA MŠk 2B06151 Institutional research plan: CEZ:AV0Z50200510 Keywords : Brominated phenols * Tetrabromobisphenol A * Laccase Subject RIV: CE - Biochemistry Impact factor: 3.253, year: 2009

  3. Thermoelectric properties of bromine filled CoSb3 skutterudite

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, Brenden R.; Crawford, Caitlin M.; McKinney, Robert W.; Parilla, Philip A.; Toberer, Eric S.

    2016-01-01

    Historically, the improved thermoelectric performance of skutterudite compounds has largely been driven by the incorporation of electropositive donors on interstitial sites. These 'rattlers' serve to optimize both electronic and thermal properties by tuning the carrier concentration and scattering phonons. In this work, we show that interstitial bromine can be incorporated into CoSb3 and assess the impact on electronic and thermal transport. In contrast to prior high pressure syntheses with iodine, interstitial bromine incorporation is achieved at ambient pressure. Transport properties are stable up to at least 375 degrees C. Bromine serves as an electronegative acceptor and can induce degenerate (>5 x 1019 cm-3) hole densities. In contrast to other p-type skutterudite compositions, bromine preserves the intrinsically high hole mobility of CoSb3 while significantly reducing the lattice thermal conductivity. The development of a stable p-type dopant for the interstitial filler site enables the development of skutterudites with both donor and acceptor interstitials to maximize phonon scattering while maintaining the high mobility of CoSb3.

  4. XAS AND XPS CHARACTERIZATION OF MERCURY BINDING ON BROMINATED ACTIVATED CARBON

    Science.gov (United States)

    Brominated powdered activated carbon sorbents have been shown to e quite effective for mercury capture when injected into the flue gas duct at coal-fired power plants and are especially useful when buring Western low-chlorine subbituminous coals. X-ray absorption spectroscopy (X...

  5. Ullmann-type coupling of brominated tetrathienoanthracene on copper and silver

    Czech Academy of Sciences Publication Activity Database

    Gutzler, R.; Cardenas, L.; Lipton-Duffin, J.; El Garah, M.; Dinca, L.E.; Szakacs, C.E.; Fu, Ch.; Gallagher, M.; Vondráček, Martin; Rybachuk, M.; Perepichka, D.F.; Rosei, F.

    2014-01-01

    Roč. 6, č. 5 (2014), 2660-2668. ISSN 2040-3364 R&D Projects: GA MŠk(CZ) LM2011029 Institutional support: RVO:68378271 Keywords : Ullmann reaction * brominated tetrathienoanthracene * high resolution photoemission * STM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.394, year: 2014

  6. Surface characteristics of photoaligned polyimide film interfacial reacted with bromine or ethanethiol

    International Nuclear Information System (INIS)

    The surface characteristics of polyimide films containing cinnamate groups which promote the uniform alignment in adjacent liquid crystal (LC) upon photodimerization by linearly polarized ultraviolet (LPUV) lights were studied [M. Schadt, K. Schmitt, V. Koznikov, V. Chignirov, Jpn. J. Appl. Phys. 31 (1992) 2155. ]. But photoalignment methods have an image sticking problem by un-reacted photosensitive functional groups, which can be a severe defect to achieve high reliability of liquid crystal display (LCD) panels. So the un-reacted photosensitive functional groups were deactivated using bromine or ethanethiol. Bromine and ethanethiol lead to the formation of carbon-bromine or carbon-sulfur bonds from carbon-carbon double bonds. The interfacial reaction of bromine or ethanethiol on the polyimide surface has been studied using in situ X-ray photoelectron spectroscopy (XPS). The change of surface tension was observed by using a contact angle analyzer. The photoelastic modulator (PEM) was used to analyze the optical anisotropy on the polyimide surface. Also, the atomic force microscopy (AFM) was used to observe the morphology of polyimide surface [K. Rajesh, M.K. Ram, S.C. Jain, S.B. Samanta, A.V. Narliker, Thin Solid Films 325 (1998) 251.

  7. METABOLISM OF BROMINATED FLAME RETARDANTS IN HUMAN ASTROCYTES AND EFFECTS ON THYROID HORMONE HOMEOSTASIS

    Science.gov (United States)

    In this proposed study, hydroxylated PBDEs and brominated phenols likely will be formed in astrocytes as a result of cytochrome p450-mediated metabolism. Previous studies have shown that polychlorinated biphenyls (PCBs) affect the regulation of thyroid hormones at the bloo...

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

    Science.gov (United States)

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

    2016-08-15

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

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

    Directory of Open Access Journals (Sweden)

    Nahid Ramazani

    2013-01-01

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

  10. Revisiting the thermochemistry of chlorine fluorides

    CERN Document Server

    Sánchez, H R

    2016-01-01

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

  11. Plutonium oxide obtainment from a plutonium fluoride

    International Nuclear Information System (INIS)

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

  12. 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.

  13. The hydride fluoride crystal structure database, HFD

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-05-20

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

  14. Bromine release from blowing snow and its impact on tropospheric chemistry

    Science.gov (United States)

    Griffiths, Paul; Yang, Xin; Abraham, N. Luke; Archibald, Alexander; Pyle, John

    2016-04-01

    In the last two decades, significant depletion of boundary layer ozone (ozone depletion events, ODEs) has been observed in both Arctic and Antarctic spring. ODEs are attributed to catalytic destruction by bromine radicals (Br plus BrO), especially during bromine explosion events (BEs), when high concentrations of BrO periodically occur. The source of bromine and the mechanism that sustains the high BrO levels are still the subject of study. Recent work by Pratt et al. (2013) posits Br2 production within saline snow and sea ice which leads to sudden ODEs. Previously, Yang et al. (2008) suggested snow could provide a source of (depleted) sea-salt aerosol if wicked from the surface of ice. They suggest that rapid depletion of bromide from the aerosol will constitute a source of photochemical Bry. Given the large sea ice extent in polar regions, this may constitute a significant source of sea salt and bromine in the polar lower atmosphere. While bromine release from blowing snow is perhaps less likely to trigger sudden ODEs, it may make a contribution to regional scale processes affecting ozone levels. Currently, the model parameterisations of Yang et al. assumes that rapid release of bromine occurs from fresh snow on sea ice during periods of strong wind. The parameterisation depends on an assumed sea-salt aerosol distribution generated via sublimation of the snow above the boundary layer, as well as taking into account the salinity of the snow. In this work, we draw on recent measurements by scientists from the British Antarctic Survey during a cruise aboard the Polarstern in the southern oceans. This has provided an extensive set of measurements of the chemical and physical characteristics of blowing snow over sea ice, and of the aerosol associated with it. Based on the observations, we have developed an improved parameterisation of the release of bromine from blowing snow. The paper presents results from the simulation performed using the United Kingdom Chemistry

  15. Fluoride solid electrolytes containing rare earth elements

    Institute of Scientific and Technical Information of China (English)

    Viera Trnovcová; Pavel P. Fedorov; Ivan Furár

    2008-01-01

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

  16. Health protection: Fluoridation and dental health.

    OpenAIRE

    1983-01-01

    Tooth decay, which affects 95 percent of Americans, is our most common health problem, costing an estimated +2 billion yearly for treatment. By the time children reach 17 years of age, 94 percent have experienced caries and 36 percent have lost one or more permanent teeth due to caries. Dental disease prevention embodies the spectrum of many activities from the fluoridation of community and school water supplies to the dental health education of the child and adult. At this stage of our knowl...

  17. Delivery Challenges for Fluoride, Chlorhexidine and Xylitol

    OpenAIRE

    Featherstone, John DB

    2006-01-01

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

  18. Effect of fluoride toothpastes on enamel demineralization

    Directory of Open Access Journals (Sweden)

    Gintner Zeno

    2006-06-01

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

  19. 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

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

    Science.gov (United States)

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

    2011-01-01

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

  1. The effective use of fluorides in public health

    DEFF Research Database (Denmark)

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

    2005-01-01

    , systematic reviews summarizing these extensive databases have indicated that water fluoridation and fluoride toothpastes both substantially reduce the prevalence and incidence of dental caries. We present four case studies that illustrate the use of fluoride in modern public health practice, focusing on......Dental caries remain a public health problem for many developing countries and for underprivileged populations in developed countries. This paper outlines the historical development of public health approaches to the use of fluoride and comments on their effectiveness. Early research and...... development was concerned with waterborne fluorides, both naturally occurring and added, and their effects on the prevalence and incidence of dental caries and dental fluorosis. In the latter half of the 20th century, the focus of research was on fluoride toothpastes and mouth rinses. More recently...

  2. High Fluoride Dentifrices for Elderly and Vulnerable Adults

    DEFF Research Database (Denmark)

    Ekstrand, Kim Rud

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

  3. Necessity to review the Brazilian regulation about fluoride toothpastes

    Directory of Open Access Journals (Sweden)

    Jaime Aparecido Cury

    2015-01-01

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

  4. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  5. Distribution of fluoride in ground water of West Virginia

    Science.gov (United States)

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

    1993-01-01

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

  6. Bone scintigraphy in fluoride treated osteoporosis

    International Nuclear Information System (INIS)

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

  7. The electric field gradient in fluorides

    International Nuclear Information System (INIS)

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

  8. 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.

  9. Monitoring of WEEE plastics in regards to brominated flame retardants using handheld XRF

    International Nuclear Information System (INIS)

    Highlights: • Specification of an empirical factor for conversion from bromine to PBB and PBDE. • The handheld XRF device was validated for this particular application. • A very large number of over 4600 pieces of monitor housings was analysed. • The recyclable fraction mounts up to 85% for TV but only 53% of PC waste plastics. • A high percentage of pieces with bromine contents of over 50,000 ppm was obtained. - Abstract: This contribution is focused on the on-site determination of the bromine content in waste electrical and electronic equipment (WEEE), in particular waste plastics from television sets (TV) and personal computer monitors (PC) using a handheld X-ray fluorescence (XRF) device. The described approach allows the examination of samples in regards to the compliance with legal specifications for polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) directly after disassembling and facilitates the sorting out of plastics with high contents of brominated flame retardants (BFRs). In all, over 3000 pieces of black (TV) and 1600 pieces of grey (PC) plastic waste were analysed with handheld XRF technique for this study. Especially noticeable was the high percentage of pieces with a bromine content of over 50,000 ppm for TV (7%) and PC (39%) waste plastics. The applied method was validated by comparing the data of handheld XRF with results obtained by GC–MS. The results showed the expected and sufficiently accurate correlation between these two methods. It is shown that handheld XRF technique is an effective tool for fast monitoring of large volumes of WEEE plastics in regards to BFRs for on-site measurements

  10. Monitoring of WEEE plastics in regards to brominated flame retardants using handheld XRF

    Energy Technology Data Exchange (ETDEWEB)

    Aldrian, Alexia, E-mail: alexia.aldrian@unileoben.ac.at [Chair of Waste Processing Technology and Waste Management, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Ledersteger, Alfred, E-mail: a.ledersteger@saubermacher.at [Saubermacher Dienstleistungs AG, Hans-Roth-Straße 1, 8073 Feldkirchen bei Graz (Austria); Pomberger, Roland, E-mail: roland.pomberger@unileoben.ac.at [Chair of Waste Processing Technology and Waste Management, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria)

    2015-02-15

    Highlights: • Specification of an empirical factor for conversion from bromine to PBB and PBDE. • The handheld XRF device was validated for this particular application. • A very large number of over 4600 pieces of monitor housings was analysed. • The recyclable fraction mounts up to 85% for TV but only 53% of PC waste plastics. • A high percentage of pieces with bromine contents of over 50,000 ppm was obtained. - Abstract: This contribution is focused on the on-site determination of the bromine content in waste electrical and electronic equipment (WEEE), in particular waste plastics from television sets (TV) and personal computer monitors (PC) using a handheld X-ray fluorescence (XRF) device. The described approach allows the examination of samples in regards to the compliance with legal specifications for polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) directly after disassembling and facilitates the sorting out of plastics with high contents of brominated flame retardants (BFRs). In all, over 3000 pieces of black (TV) and 1600 pieces of grey (PC) plastic waste were analysed with handheld XRF technique for this study. Especially noticeable was the high percentage of pieces with a bromine content of over 50,000 ppm for TV (7%) and PC (39%) waste plastics. The applied method was validated by comparing the data of handheld XRF with results obtained by GC–MS. The results showed the expected and sufficiently accurate correlation between these two methods. It is shown that handheld XRF technique is an effective tool for fast monitoring of large volumes of WEEE plastics in regards to BFRs for on-site measurements.

  11. Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

    Directory of Open Access Journals (Sweden)

    C. R. Thompson

    2014-11-01

    Full Text Available The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, detection of atmospheric I2. Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, constrained with measurements from the 2009 OASIS field campaign in Barrow, Alaska. We simulated a 7 day period during late March that included a full ozone depletion event lasting 3 days and subsequent ozone recovery to study the interactions of halogen radicals under these different conditions. In addition, the effects of iodine added to our base model were investigated. While bromine atoms were primarily responsible for ODEs, chlorine and iodine were found to enhance the depletion rates and iodine was found to be more efficient per atom at depleting ozone than Br. The interaction between chlorine and bromine is complex, as the presence of chlorine can increase the recycling and production of Br atoms, while also increasing reactive bromine sinks under certain conditions. Chlorine chemistry was also found to have significant impacts on both HO2 and RO2. The results of this work highlight the need for future studies on the production mechanisms of Br2 and Cl2, as well as on the potential

  12. Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

    Science.gov (United States)

    Thompson, C. R.; Shepson, P. B.; Liao, J.; Huey, L. G.; Apel, E. C.; Cantrell, C. A.; Flocke, F.; Orlando, J.; Fried, A.; Hall, S. R.; Hornbrook, R. S.; Knapp, D. J.; Mauldin, R. L., III; Montzka, D. D.; Sive, B. C.; Ullmann, K.; Weibring, P.; Weinheimer, A.

    2015-08-01

    The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indications of active iodine chemistry through observed enhancements in filterable iodide, probable detection of tropospheric IO, and recently, observation of snowpack photochemical production of I2. Despite decades of research, significant uncertainty remains regarding the chemical mechanisms associated with the bromine-catalyzed depletion of ozone, as well as the complex interactions that occur in the polar boundary layer due to halogen chemistry. To investigate this, we developed a zero-dimensional photochemical model, constrained with measurements from the 2009 OASIS field campaign in Barrow, Alaska. We simulated a 7-day period during late March that included a full ozone depletion event lasting 3 days and subsequent ozone recovery to study the interactions of halogen radicals under these different conditions. In addition, the effects of iodine added to our Base Model were investigated. While bromine atoms were primarily responsible for ODEs, chlorine and iodine were found to enhance the depletion rates and iodine was found to be more efficient per atom at depleting ozone than Br. The interaction between chlorine and bromine is complex, as the presence of chlorine can increase the recycling and production of Br atoms, while also increasing reactive bromine sinks under certain conditions. Chlorine chemistry was also found to have significant impacts on both HO2 and RO2, with organic compounds serving as the primary reaction partner for Cl atoms. The results of this work highlight the need for future

  13. A case study of a transported bromine explosion event in the Canadian high arctic

    Science.gov (United States)

    Zhao, X.; Strong, K.; Adams, C.; Schofield, R.; Yang, X.; Richter, A.; Friess, U.; Blechschmidt, A.-M.; Koo, J.-H.

    2016-01-01

    Ozone depletion events in the polar troposphere have been linked to extremely high concentrations of bromine, known as bromine explosion events (BEE). However, the optimum meteorological conditions for the occurrence of these events remain uncertain. On 4-5 April 2011, a combination of both blowing snow and a stable shallow boundary layer was observed during a BEE at Eureka, Canada (86.4°W, 80.1°N). Measurements made by a Multi-Axis Differential Optical Absorption Spectroscopy spectrometer were used to retrieve BrO profiles and partial columns. During this event, the near-surface BrO volume mixing ratio increased to ~20 parts per trillion by volume, while ozone was depleted to ~1 ppbv from the surface to 700 m. Back trajectories and Global Ozone Monitoring Experiment-2 satellite tropospheric BrO columns confirmed that this event originated from a bromine explosion over the Beaufort Sea. From 30 to 31 March, meteorological data showed high wind speeds (24 m/s) and elevated boundary layer heights (~800 m) over the Beaufort Sea. Long-distance transportation (~1800 km over 5 days) to Eureka indicated strong recycling of BrO within the bromine plume. This event was generally captured by a global chemistry-climate model when a sea-salt bromine source from blowing snow was included. A model sensitivity study indicated that the surface BrO at Eureka was controlled by both local photochemistry and boundary layer dynamics. Comparison of the model results with both ground-based and satellite measurements confirmed that the BEE observed at Eureka was triggered by transport of enhanced BrO from the Beaufort Sea followed by local production/recycling under stable atmospheric shallow boundary layer conditions.

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

    International Nuclear Information System (INIS)

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

  15. A health risk assessment for fluoride in Central Europe

    OpenAIRE

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

    2007-01-01

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

  16. Use of professionally administered topical fluorides in Asia

    OpenAIRE

    Tenuta, LMA; Fox, CH; Lo, ECM

    2012-01-01

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

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

    OpenAIRE

    Easley, M W

    1990-01-01

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

  18. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-12-01

    Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by

  19. The effect of bromination of carbon fibers on the coefficient of thermal expansion of graphite fiber-epoxy composites

    Science.gov (United States)

    Jaworske, D. A.; Maciag, C.

    1987-01-01

    To examine the effect of bromination of carbon fibers on the coefficient of thermal expansion (CTE) of carbon fiber epoxy composites, several pristine and brominated carbon fiber-epoxy composite samples were subjected to thermomechanical analysis. The CTE's of these samples were measured in the uniaxial and transverse directions. The CTE was dominated by the fibers in the uniaxial direction, while it was dominated by the matrix in the transverse directions. Bromination had no effect on the CTE of any of the composites. In addition, the CTE of fiber tow was measured in the absence of a polymer matrix, using an extension probe. The results from this technique were inconclusive.

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

    OpenAIRE

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

    2010-01-01

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

  1. 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.

  2. Oxidative stress in cases of chronic fluoride intoxication

    OpenAIRE

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

    2009-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

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

    OpenAIRE

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

    2015-01-01

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

  5. Combustion and inorganic bromine emission of waste printed circuit boards in a high temperature furnace

    International Nuclear Information System (INIS)

    Highlights: ► The combustion efficiency of waste printed circuit boards (PCBs) depends on temperature, excess air factor, and high temperature zone residence time. Temperature has the most significant impact. Under the proposed condition, combustion of waste PCBs alone is quite complete within the furnace. ► High temperature prompts a more complete bromine release and conversion. When temperature is high enough, 99.9% organobrominated compounds, the potential precursors for brominated dixoins formation, are destroyed efficiently and convert to inorganic bromine in flue gas, as HBr and Br2. ► Temperature has crucial influence over the inhibition of HBr conversion to Br2, while the oxygen partial pressure plays a reverse role in the conversion to a very small extent. Increasing temperature will decrease the volume percentage ratio of Br2/HBr in flue gas greatly. ► The thermodynamic equilibrium approach of bromine conversion was investigated. The two forms of inorganic bromine in flue gas substantially reach thermodynamic equilibrium within 0.25 s. Under the proposed operating condition, the reaction of Br transfer and conversion finish. - Abstract: High temperature combustion experiments of waste printed circuit boards (PCBs) were conducted using a lab-scale system featuring a continuously-fed drop tube furnace. Combustion efficiency and the occurrence of inorganic bromine (HBr and Br2) were systematically studied by monitoring the main combustion products continuously. The influence of furnace temperature (T) was studied from 800 to 1400 °C, the excess air factor (EAF) was varied from 1.2 to 1.9 and the residence time in the high temperature zone (RTHT) was set at 0.25, 0.5, or 0.75 s. Combustion efficiency depends on temperature, EAF and RTHT; temperature has the most significant effect. Conversion of organic bromine from flame retardants into HBr and Br2 depends on temperature and EAF. Temperature has crucial influence over the ratio of HBr to Br2

  6. Scientific Opinion on Dietary Reference Values for fluoride

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA

    2013-08-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

  12. Optical restoration of irradiated lead fluoride crystals

    International Nuclear Information System (INIS)

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

  13. Optical restoration of irradiated lead fluoride crystals

    International Nuclear Information System (INIS)

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

  14. Optical Restoration of Lead Fluoride Crystals

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Solovyov, Vyacheslav; Wiesmann, Harold

    2009-11-24

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

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

    Science.gov (United States)

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

    2008-01-01

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

  17. Fluoride uptake from restorative dental materials by human enamel

    International Nuclear Information System (INIS)

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

  18. 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...

  19. 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…

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    International Nuclear Information System (INIS)

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

  2. Electrorecovery of tantalum in molten fluorides

    International Nuclear Information System (INIS)

    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)

  3. LUMINESCENCE IN POTENTIAL FLUORIDE GLASS LASERS

    OpenAIRE

    Jørgensen, C.

    1987-01-01

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

  4. Fluoride microresonators for mid-IR applications

    CERN Document Server

    Grudinin, Ivan S; Yu, Nan

    2016-01-01

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

  5. Distribution of brominated compounds within the sponge Aplysina aerophoba: coupling of X-ray microanalysis with cryofixation techniques.

    Science.gov (United States)

    Turon, X; Becerro, M A; Uriz, M J

    2000-08-01

    The major secondary metabolites of the sponge Aplysina aerophoba are brominated compounds. X-ray energy dispersive microanalysis was therefore used to locate secondary metabolites via the Br signal in energy emission spectra from sponge sections. To test the reliability of this method in the face of the loss or redistribution of metabolites during processing, we compared the results obtained by conventional aldehyde fixation with those obtained by cryofixation and cryosubstitution with and without cryoembedding. Bromine appeared to be concentrated in two sponge structures, viz. fibres and spherulous cells, when cryofixed material was examined. However, X-ray microanalysis failed to demonstrate the presence of bromine in spherulous cells in chemically fixed samples, showing the need for cryotechniques to avoid the loss of compounds. Cryofixation plus cryosubstitution methods performed best regarding structural preservation and the immobilization of metabolites. The presence of bromine in the spherulous cells suggests that this cell type is the producer of the secondary metabolites, as described for other sponge species. Nevertheless, the presence of bromine in sponge fibres indicates that they can accumulate metabolic substances, although we have been unable to assess whether the chemicals are in their original form or in a modified state within the fibres. A. aerophoba has both bacterial and cyanobacterial symbionts in its mesohyl; the absence of brominated compounds in them contrasts with previous findings in other sponges with prokaryote symbionts. PMID:10955726

  6. 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.

  7. 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......A series of sorption of fluoride on calcined magnesite are obtained from thermostatic pH-chemostat and jar test experiments. The fluoride removal is observed not to start instantly, as normal, but after a lag time of up to ½ an hour of contact time. A model for sorption kinetics is developed, based...

  8. Molten-Phase Hydrolysis Stage Analysis and Experiments for the Calcium Bromine Thermochemical Cycle

    International Nuclear Information System (INIS)

    The goal of the United States Department of Energy Nuclear Hydrogen Initiative as linked with the Generation IV Nuclear Energy Systems Initiative for Gas Reactor Deployment is to develop a cost-effective, proliferation-resistant, low-greenhouse-gas emissions, and sustainable, nuclear-based energy supply system. The calcium-bromine cycle under development at Argonne National Laboratory combines both experimental and modeling studies of a novel continuous 'hybrid' cycle for hydrogen production, where 'hybrid' means that both nuclear heat and electricity are employed. Engineering the calcium-bromine cycle for continuous operation should facilitate its practical development since there will be an inherent advantage to using components and materials which will operate in a constant, non-cycling chemical and thermal environment. This paper focuses on the first and important calcium bromide hydrolysis stage to generate hydrogen bromide, which when split by electrolysis, produces hydrogen. (authors)

  9. Co-doping of Potassium and Bromine in Carbon Nanotubes: A Density Functional Theory Study

    Institute of Scientific and Technical Information of China (English)

    XIAO Yong; YAN xiao-Hong; DING Jian-Wen

    2007-01-01

    We investigate the co-doping of potassium and bromine in singlewalled carbon nanotubes (SWCNTs)and doublewalled carbon nanotubes(DWCNTs)based on density functional theory.In the co-doped(6,O)SWCNTs,the 4s electron of potassium is transferred to nanotube and Br,leading to the n-type feature of SWCNTs.When potassium is intercalated into inner tube and bromine is put on outer tube,the positive and negative charges reside on the outer and inner tubes of the(7.0)@(16,0)DWCNT,respectively.It is expected that DWCNTs would be an ideal candidate for p-n junction and diode applications.

  10. Stratospheric ozone depletion and future levels of atmospheric chlorine and bromine

    Science.gov (United States)

    Prather, Michael J.; Watson, Robert T.

    1990-01-01

    The rise in atmospheric chlorine levels caused by the emission of chlorofluorocarbons and other halocarbons is thought to be the main cause of the appearance of the Antarctic ozone 'hole' in the late 1970s, and the more modest ozone depletion observed over parts of the Northern Hemisphere. Atmospheric bromine, also associated with halocarbon emissions, is believed to contribute to ozone depletion. Over the next decade, further increases in these compounds are inevitable. Model calculations show that by the end of the next century, atmospheric chlorine and bromine levels may return to those prevalent before the onset of the ozone hole, but only if more stringent regulations are applied to halocarbon production than those currently proposed.

  11. First measurements of total chlorine and bromine in the lower stratosphere

    International Nuclear Information System (INIS)

    A total halogen collection system employing ultra-pure activated charcoal traps has been developed for use in the stratosphere aboard aircraft and balloon sampling platforms. Neutron activation techniques for low-level chlorine, bromine, and iodine analysis within the activated charcoal sampling matrix were developed. Initial results from six aircraft flights and one balloon mission in the lower stratosphere are presented for latitudes ranging from 160N to 670N. Little variability was observed in twelve total, gaseous and particulate chlorine (Cl/sub tot/) determinations as a function of latitude at 20 km with values ranging between 2.7 +- 9 ppbV and 3.2 +- .7 ppbV. Five total bromine (Br/sub tot/) values showed substantial variability ranging from 7 +- 4 pptV to 40 +- 11 pptV. No iodine was observed in any samples but a calculated I/sub tot/ upper limit of < 3 pptV was determined

  12. 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.

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

    Science.gov (United States)

    Bánóczy, Jolán; Rugg-Gunn, Andrew J

    2007-10-01

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

  14. Fluoride-induced disruption of reproductive hormones in men

    International Nuclear Information System (INIS)

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

  15. Occupational exposure to brominated flame retardants : With emphasis on polybrominated diphenyl ethers

    OpenAIRE

    Thuresson, Kaj

    2004-01-01

    Brominated flame retardants (BFRs) are a diverse group of chemicals, which are used to slow down or inhibit the development of fires. BFRs are incorporated into a wide range of consumer products that are considered as potential fire hazards, such as TV-sets, household appliances, computers, and textiles. The production and use of BFRs is extensive and consists of mainly tetrabromobisphenol A (TBBPA), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecan (HBCD). BFRs in general, but...

  16. Assessing oestrogenic effects of brominated flame retardants Hexabromocyclododecane and Tetrabromobisphenol A on MCF-7 cells

    Czech Academy of Sciences Publication Activity Database

    Dorosh, Andriy; Děd, Lukáš; Elzeinová, Fatima; Pěknicová, Jana

    2010-01-01

    Roč. 56, - (2010), s. 35-39. ISSN 0015-5500 R&D Projects: GA MŠk(CZ) 1M06011; GA MŠk(CZ) 2B06151 Institutional research plan: CEZ:AV0Z50520701 Keywords : endocrine disruptors * BRF - brominated flame retardant * MCF-7 cells * TFF1 - trefoil factor Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 0.729, year: 2010

  17. Brominated Skeletal Components of the Marine Demosponges, Aplysina cavernicola and Ianthella basta: Analytical and Biochemical Investigations

    OpenAIRE

    Eike Brunner; Peter Proksch; Hermann Ehrlich; Renate Schulze; Susanne Ueberlein; Hendrik Niemann; Kurt Kunze; Karl-Heinz van Pée

    2013-01-01

    Demosponges possess a skeleton made of a composite material with various organic constituents and/or siliceous spicules. Chitin is an integral part of the skeleton of different sponges of the order Verongida. Moreover, sponges of the order Verongida, such as Aplysina cavernicola or Ianthella basta, are well-known for the biosynthesis of brominated tyrosine derivates, characteristic bioactive natural products. It has been unknown so far whether these compounds are exclusively present in the ce...

  18. Reductive Dehalogenation of Brominated Phenolic Compounds by Microorganisms Associated with the Marine Sponge Aplysina aerophoba

    OpenAIRE

    Ahn, Young-Beom; Rhee, Sung-Keun; Fennell, Donna E.; Kerkhof, Lee J.; Hentschel, Ute; Häggblom, Max M.

    2003-01-01

    Marine sponges are natural sources of brominated organic compounds, including bromoindoles, bromophenols, and bromopyrroles, that may comprise up to 12% of the sponge dry weight. Aplysina aerophoba sponges harbor large numbers of bacteria that can amount to 40% of the biomass of the animal. We postulated that there might be mechanisms for microbially mediated degradation of these halogenated chemicals within the sponges. The capability of anaerobic microorganisms associated with the marine sp...

  19. Ship-source pollution by polychlorinated biphenyls and brominated flame retardants

    OpenAIRE

    ČULIN, Jelena; Bielić, Toni

    2015-01-01

    Polychlorinated biphenyls (PCBs) and brominated flame retardants (BFRs) are groups of anthropogenic contaminants that have been routinely used in many applications for several decades. Prior to the discovery of their detrimental health effects and subsequent implementation of regulatory measures they were widely applied in shipbuilding. They are still found onboard active and inactive ships and pose a risk to human and environment. Therefore, it is important to continue to carry out preven...

  20. Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

    Directory of Open Access Journals (Sweden)

    J. P. Parrella

    2012-04-01

    Full Text Available We present a new model for the global tropospheric chemistry of inorganic bromine (Bry coupled to oxidant-aerosol chemistry in the GEOS-Chem chemical transport model (CTM. Sources of tropospheric Bry include debromination of sea-salt aerosol, photolysis and oxidation of short-lived bromocarbons, and transport from the stratosphere. Comparison to a GOME-2 satellite climatology of tropospheric BrO columns shows that the model can reproduce the observed increase of BrO with latitude, the northern mid-latitudes maximum in winter, and the Arctic maximum in spring. This successful simulation is contingent on the HOBr + HBr reaction taking place in aqueous aerosols and ice clouds. Bromine chemistry in the model decreases tropospheric ozone concentrations by <1−8 nmol mol−1 (6.5% globally, with the largest effects in the northern extratropics in spring. The global mean tropospheric OH concentration decreases by 4%. Inclusion of bromine chemistry improves the ability of global models (GEOS-Chem and p-TOMCAT to simulate observed 19th-century ozone and its seasonality. Bromine effects on tropospheric ozone are comparable in the present-day and pre-industrial atmospheres so that estimates of anthropogenic radiative forcing are minimally affected. Br atom concentrations are 40% higher in the pre-industrial atmosphere due to lower ozone, which would decrease by a factor of 2 the atmospheric lifetime of elemental mercury against oxidation by Br. This suggests that historical anthropogenic mercury emissions may have mostly deposited to northern mid-latitudes, enriching the corresponding surface reservoirs. The persistent rise in background surface ozone at northern mid-latitudes during the past decades could possibly contribute to the observations of elevated mercury in subsurface waters of the North Atlantic.

  1. Tropospheric bromine chemistry: implications for present and pre-industrial ozone and mercury

    Directory of Open Access Journals (Sweden)

    J. P. Parrella

    2012-08-01

    Full Text Available We present a new model for the global tropospheric chemistry of inorganic bromine (Bry coupled to oxidant-aerosol chemistry in the GEOS-Chem chemical transport model (CTM. Sources of tropospheric Bry include debromination of sea-salt aerosol, photolysis and oxidation of short-lived bromocarbons, and transport from the stratosphere. Comparison to a GOME-2 satellite climatology of tropospheric BrO columns shows that the model can reproduce the observed increase of BrO with latitude, the northern mid-latitudes maximum in winter, and the Arctic maximum in spring. This successful simulation is contingent on the HOBr + HBr reaction taking place in aqueous aerosols and ice clouds. Bromine chemistry in the model decreases tropospheric ozone mixing ratios by <1–8 nmol mol−1 (6.5% globally, with the largest effects in the northern extratropics in spring. The global mean tropospheric OH concentration decreases by 4%. Inclusion of bromine chemistry improves the ability of global models (GEOS-Chem and p-TOMCAT to simulate observed 19th-century ozone and its seasonality. Bromine effects on tropospheric ozone are comparable in the present-day and pre-industrial atmospheres so that estimates of anthropogenic radiative forcing are minimally affected. Br atom concentrations are 40% higher in the pre-industrial atmosphere due to lower ozone, which would decrease by a factor of 2 the atmospheric lifetime of elemental mercury against oxidation by Br. This suggests that historical anthropogenic mercury emissions may have mostly deposited to northern mid-latitudes, enriching the corresponding surface reservoirs. The persistent rise in background surface ozone at northern mid-latitudes during the past decades could possibly contribute to the observations of elevated mercury in subsurface waters of the North Atlantic.

  2. A comparison of the virucidal properties of chlorine, chlorine dioxide, bromine chloride and iodine.

    OpenAIRE

    Taylor, G R; Butler, M

    1982-01-01

    Chlorine dioxide, bromine chloride and iodine were compared with chlorine as virucidal agents. Under optimal conditions all disinfectants were effective at low concentrations, but each disinfectant responded differently to acidity and alkalinity. Disinfection by chlorine was impaired by the presence of ammonia, but the other disinfectants retained much of their potency. Disinfection of poliovirus by iodine resulted in structural changes in the virions as seen by electron micrroscopy, but the ...

  3. Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

    OpenAIRE

    N. Bobrowski; Giuffrida, G

    2012-01-01

    Over a 3-yr period, from 2006 to 2009, frequent scattered sunlight DOAS measurements were conducted at Mt. Etna at a distance of around 6 km downwind from the summit craters. During the same period and in addition to these measurements, volcanic observations were made by regularly visiting various parts of Mt. Etna. Here, results from these measurements and observations are presented and their relation is discussed. The focus of the investigation is the bromine monoxide/sulphur dioxide (BrO ...

  4. Mercury oxidation from bromine chemistry in the free troposphere over the southeastern US

    OpenAIRE

    S. Coburn; Dix, B.; Edgerton, E.; Holmes, C. D; Kinnison, D.; Liang, Q; A. ter Schure; Wang, S.; R. Volkamer

    2015-01-01

    The elevated deposition of atmospheric mercury over the Southeastern United States is currently not well understood. Here we measure partial columns and vertical profiles of bromine monoxide (BrO) radicals, a key component of mercury oxidation chemistry, to better understand the processes and altitudes at which mercury is being oxidized in the atmosphere. We use the data from a ground-based MAX-DOAS instrument located at a coastal site ~ 1 km from the Gulf o...

  5. Toxicity of brominated flame retardants with focus on retinoid system disturbances

    OpenAIRE

    Litens Karlsson, Sabina

    2015-01-01

    Background: Brominated flame retardants (BFR) are detected in the environment and biota all over the world. They contribute to the human body burden of industrial chemicals and exposure is mainly via food. Indoor dust contributes substantially in some exposure situations, which involve small children. Regulatory restrictions and bans have been introduced as some BFRs can impact proper development, potentially via the endocrine system. Objectives: The study aim was to clarify the role of...

  6. Volcanic plumes: Evaluation of spectroscopic measurements, early detection, and bromine chemistry

    OpenAIRE

    Vogel, Leif

    2011-01-01

    Volcanos emit inter alia highly reactive chemical compounds, which influence the atmosphere on a local, regional and global scale. Subject of this study are measurements of volcanic plumes via differential optical absorption spectroscopy (DOAS). A new tool for analysis and optimisation of evaluation schemes was developed, which is applicable to any DOAS measurement. Measurements of bromine monoxide (BrO) and sulphur dioxide (SO2 ) are presented, which were gathered at Mt. Etna (Italy) and Pac...

  7. Thermal Recycling of Brominated Flame Retardants with Fe2O3.

    Science.gov (United States)

    Altarawneh, Mohammednoor; Ahmed, Oday H; Jiang, Zhong-Tao; Dlugogorski, Bogdan Z

    2016-08-01

    Plastics containing brominated flame retardants (BFRs) constitute the major fraction of nonmetallic content in e-waste. Co-pyrolysis of BFRs with hematite (Fe2O3) represents a viable option for the thermal recycling of BFRs. Consensus of experimental findings confirms the excellent bromine fixation ability of Fe2O3 and the subsequent formation of iron bromides. This contribution provides a comprehensive mechanistic account of the primary reactions between a cluster model of Fe2O3 and major bromine-bearing products from the decomposition of tetrabromobisphenol A (TBBA), the most commonly deployed BFR. We estimate the thermo-kinetic parameters for interactions of Fe2O3 with HBr, brominated alkanes and alkenes, bromobenzene, and bromophenol. Dissociative addition of HBr at a Fe-O bond proceeds through a trivial barrier of 8.2 kcal/mol with fitted parameters in the Arrhenius equation of k(T) = 7.96 × 10(11) exp(-6400/RT) s(-1). The facile and irreversible nature for HBr addition to Fe2O3 accords with the experimentally reported 90% reduction in HBr emission when Fe2O3 interacts with TBBA pyrolysates. A detailed kinetic analysis indicates that, transformation of Fe2O3 into iron bromides and oxybromides occurs via successive addition of HBr to Fe(Br)-O(H) entities. Elimination of a water molecule proceeds through an intramolecular H transfer. A direct elimination one-step mechanism operates in the dehydrohalogenation of bromoethane into ethene over Fe2O3. Dissociative decomposition and direct elimination channels assume comparable reaction rates in formation of acetylene from vinyl bromide. Results from this study provide an atomic-based insight into a promising thermal recycling route of e-waste. PMID:27366936

  8. Brominated Biphenyls Prime Extensive Microbial Reductive Dehalogenation of Aroclor 1260 in Housatonic River Sediment

    OpenAIRE

    Bedard, Donna L.; Van Dort, Heidi; DeWeerd, Kim A.

    1998-01-01

    The upper Housatonic River and Woods Pond (Lenox, Mass.), a shallow impoundment on the river, are contaminated with polychlorinated biphenyls (PCBs), the residue of partially dechlorinated Aroclor 1260. Certain PCB congeners have the ability to activate or “prime” anaerobic microorganisms in Woods Pond sediment to reductively dehalogenate the Aroclor 1260 residue. We proposed that brominated biphenyls might have the same effect and tested the priming activities of 14 mono-, di-, and tribromin...

  9. The bromination Hypocrellin A and the spectra character of the reaction of gelatin with the derivative

    International Nuclear Information System (INIS)

    The bromination derivates of hypocrellin A (Br-HA) was prepared in this paper, and the photodynamic activity also was appraised. UV-Vis spectroscopy and Fluorescence spectrophotometer were employed to detect the reaction of Br-HA with gelatin. The result shown the Br-HA can react with gelatin, and the HA-Br also photodegraded the pyridinoline cross-link formation in gelatin.

  10. Reactive airways dysfunction and systemic complaints after mass exposure to bromine.

    OpenAIRE

    Woolf, A; Shannon, M.

    1999-01-01

    Occasionally children are the victims of mass poisoning from an environmental contaminant that occurs due to an unexpected common point source of exposure. In many cases the contaminant is a widely used chemical generally considered to be safe. In the following case, members of a sports team visiting a community for an athletic event were exposed to chemicals while staying at a local motel. Bromine-based sanitizing agents and other chemicals such as hydrochloric acid, which were used in exces...

  11. On bromine, nitrogen oxides and ozone depletion in the tropospheric plume of Erebus volcano (Antarctica)

    OpenAIRE

    Boichu, Marie; Oppenheimer, Clive; Roberts, Tjarda J.; V. I. Tsanev; Kyle, Philip R

    2011-01-01

    International audience Since the discovery of bromine oxide (BrO) in volcanic emissions, there has been speculation concerning its role in chemical evolution and notably ozone depletion in volcanic plumes. We report the first measurements using Differential Optical Absorption Spectroscopy (DOAS) of BrO in the tropospheric plume of the persistently degassing Erebus volcano (Antarctica). These are the first observations pertaining to emissions from an alkaline phonolitic magma. The observed ...

  12. Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

    OpenAIRE

    Thompson, C. R.; P. B. Shepson; Liao, J.; Huey, L.G.; E. C. Apel; Cantrell, C. A.; Flocke, F.; Orlando, J.; Fried, A.; Hall, S. R; R. S. Hornbrook; D. J. Knapp; Mauldin III, R. L; Montzka, D. D.; B. C. Sive

    2014-01-01

    The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there ha...

  13. Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska

    OpenAIRE

    Thompson, C. R.; P. B. Shepson; Liao, J.; Huey, L.G.; E. C. Apel; Cantrell, C. A.; Flocke, F.; Orlando, J.; Fried, A.; Hall, S. R; R. S. Hornbrook; D. J. Knapp; Mauldin III, R. L; Montzka, D. D.; B. C. Sive

    2015-01-01

    The springtime depletion of tropospheric ozone in the Arctic is known to be caused by active halogen photochemistry resulting from halogen atom precursors emitted from snow, ice, or aerosol surfaces. The role of bromine in driving ozone depletion events (ODEs) has been generally accepted, but much less is known about the role of chlorine radicals in ozone depletion chemistry. While the potential impact of iodine in the High Arctic is more uncertain, there have been indicatio...

  14. Brominated and organophosphate flame retardants in selected consumer products on the Japanese market in 2008

    International Nuclear Information System (INIS)

    Highlights: → We examined the flame retardants in electronics, curtains, wallpaper and insulator. → Use of alternative brominated and organophosphate flame retardants was suggested. → All the products investigated also contained PBDEs, TBBPA and polybromophenols. → Incorporation of recycled materials containing hazardous substance was suggested. - Abstract: The concentrations of traditional brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) in new consumer products, including electronic equipment, curtains, wallpaper, and building materials, on the Japanese market in 2008 were investigated. Although some components of the electronic equipment contained bromine at concentrations on the order of percent by weight, as indicated by X-ray fluorescence analysis, the bromine content could not be fully accounted for by the BFRs analyzed in this study, which included polybrominated diphenylethers, decabromodiphenyl ethane, tetrabromobisphenol A, polybromophenols, and hexabromocyclododecanes. These results suggest the use of alternative BFRs such as newly developed formulations derived from tribromophenol, tetrabromobisphenol A, or both. Among the 11 OPFRs analyzed, triphenylphosphate was present at the highest concentrations in all the products investigated, which suggests the use of condensed-type OPFRs as alternative flame retardants, because they contain triphenylphosphate as an impurity. Tripropylphosphate was not detected in any samples; and trimethylphosphate, tributyl tris(2-butoxyethyl)phosphate, and tris(1,3-dichloro-2-propyl)phosphate were detected in only some components and at low concentrations. Note that all the consumer products evaluated in this study also contained traditional BFRs in amounts that were inadequate to impart flame retardancy, which implies the incorporation of recycled plastic materials containing BFRs that are of global concern.

  15. Simultaneous determination of bromine and iodine in the rat thyroid by short-term INAA

    Czech Academy of Sciences Publication Activity Database

    Pavelka, Stanislav; Vobecký, Miloslav; Babický, Arnošt

    Tokyo: Tokyo Metropolitan University, 2007. s. 118-118. [International Conference on Modern Trends in Activation Analysis /12./. 16.09.2007-21.09.2007, Hachioji] R&D Projects: GA AV ČR(CZ) KJB401630701 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z40310501 Keywords : spo2 * bromine * iodine * thyroid gland Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition

  16. Detailed modeling of the atmospheric degradation mechanism of very-short lived brominated species

    OpenAIRE

    G. Krysztofiak; Catoire, Valéry; Poulet, G.; Marécal, V.; Pirre, Michel; Louis, F.; Canneaux, S.; B. Josse

    2012-01-01

    International audience Detailed chemical reaction schemes for the atmospheric degradations of the very short-lived species (VSLS) bromoform (CHBr3) and dibromomethane (CH2Br2) have been established. These degradation schemes have been implemented in the meteorological/tracer transport model CATT-BRAMS used in the present case as pseudo one-dimensional model with chemistry of CH4, CO, HOx, NOx, NOy and Ox. They include the main possible reactions of the intermediate brominated peroxy radica...

  17. Meteorological controls on the vertical distribution of bromine monoxide in the lower troposphere

    OpenAIRE

    Peterson, P K; Simpson, W. R.; K. A. Pratt; P. B. Shepson; U. Frieß; J. Zielcke; Platt, U.; Walsh, S J; S. V. Nghiem

    2014-01-01

    Multiple axis differential absorption spectroscopy (MAX-DOAS) measurements of bromine monoxide (BrO) probed the vertical structure of halogen activation events during March–May 2012 at Barrow, Alaska. An analysis of the BrO averaging kernels and degrees of freedom obtained by optimal-estimation-based inversions from raw MAX-DOAS measurements reveals the information is best represented by reducing the retrieved BrO profile to two ...

  18. Formation and chemical reactivity of carbon fibers prepared by defluorination of graphite fluoride

    Science.gov (United States)

    Hung, Ching-Cheh

    1994-01-01

    Defluorination of graphite fluoride (CFX) by heating to temperatures of 250 to 450 C in chemically reactive environments was studied. This is a new and possibly inexpensive process to produce new carbon-based materials. For example, CF 0.68 fibers, made from P-100 carbon fibers, can be defluorinated in BrH2C-CH = CH-CH2Br (1,4-dibromo-2butene) heated to 370 C, and graphitized to produce fibers with an unusually high modulus and a graphite layer structure that is healed and cross-linked. Conversely, a sulfur-doped, visibly soft carbon fiber was produced by defluorinating CF 0.9 fibers, made from P-25, in sulfur (S) vapor at 370 C and then heating to 660 C in nitrogen (N2). Furthermore, defluorination of the CF 0.68 fibers in bromine (Br2) produced fragile, structurally damaged carbon fibers. Heating these fragile fibers to 1100 C in N2 caused further structural damage, whereas heating to 150 C in bromoform (CHBr3) and then to 1100 C in N2 healed the structural defects. The defluorination product of CFX, tentatively called activated graphite, has the composition and molecular structure of graphite, but is chemically more reactive. Activated graphite is a scavenger of manganese (Mn), and can be intercalated with magnesium (Mg). Also, it can easily collect large amounts of an alloy made from copper (Cu) and type 304 stainless steel to form a composite. Finally, there are indications that activated graphite can wet metals or ceramics, thereby forming stronger composites with them than the pristine carbon fibers can form.

  19. MISCIBILITY AND MORPHOLOGY OF THIN FILMS OF BLENDS OF POLYSTYRENE WITH BROMINATED POLYSTYRENES: EFFECTS OF VARYING THE MOLECULAR WEIGHT,BROMINATION DEGREE AND ANNEALING

    Institute of Scientific and Technical Information of China (English)

    Rui Song; De-bin Yang; Ling-hao He; Guang-tao Yao

    2006-01-01

    Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poly(styrene-co-p-bromo-styrene), I.e.,PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised. In this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy (AFM). In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Mw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film.

  20. Effect of Bromine Substitution on Human Dermal Absorption of Polybrominated Diphenyl Ethers.

    Science.gov (United States)

    Abdallah, Mohamed Abou-Elwafa; Pawar, Gopal; Harrad, Stuart

    2015-09-15

    Human dermal absorption of eight mono- to deca-brominated diphenyl ethers (PBDEs) was investigated for the first time using EPISKIN human skin equivalent tissue. Using a standard in vitro protocol, EPISKIN tissues mounted in specially designed diffusion cells were exposed to the target PBDEs for 24 h. Estimated steady-state flux (Jss) and permeation coefficients (Papp) across the skin increased with decreasing bromine substitution from BDE-153 (Papp = 4.0 × 10(-4) cm/h) to BDE-1 (Papp = 1.1 × 10(-2) cm/h). This was accompanied by an increase in the time required to traverse the skin tissue into the receptor fluid (lag time) from 0.25 h for BDE-1 to 1.26 h for BDE-153. Papp values for the studied PBDEs were correlated significantly (P water solubility and log KOW. While less brominated congeners achieved faster dermal penetration, higher PBDEs displayed greater accumulation within the skin tissue. The PBDEs thus accumulated represent a contaminant depot from which they may be slowly released to the systemic circulation over a prolonged period. Maximal percutaneous penetration was observed for BDE-1 (∼ 30% of the applied 500 ng/cm(2) dose). Interestingly, BDE-183 and BDE-209 showed very low dermal absorption, exemplified by a failure to reach the steady state within the 24 h exposure period that was studied. PMID:26301594

  1. Effects of Assistant Solvents and Mixing Intensity on the Bromination Process of Butyl Rubber

    Institute of Scientific and Technical Information of China (English)

    王伟; 邹海魁; 初广文; 向阳; 彭晗; 陈建峰

    2014-01-01

    A slow bromination process of butyl rubber (IIR) suffers from low efficiency and low selectivity (S) of target-product. To obtain suitable approach to intensify the process, effects of assistant solvents and mixing inten-sity on the bromination process were systemically studied in this paper. The reaction process was found constantly accelerated with the increasing dosage and polarity of assistant solvent. Hexane with 30%(by volume) dichloro-methane was found as the suitable solvent component, where the stable conversion of 1,4-isoprene transferring to target product (xA1s) of 80.2%and the corresponding S of 91.2%were obtained in 5 min. The accelerated reaction process was demonstrated being remarkably affected by mixing intensity until the optimal stirring rate of 1100 r·min-1 in a stirred tank reactor. With better mixing condition, a further intensification of the process was achieved in a ro-tating packed bed (RPB) reactor, where xA1s of 82.6% and S of 91.9% were obtained in 2 min. The usage of the suitable solvent component and RPB has potential application in the industrial bromination process intensification.

  2. Monitoring of WEEE plastics in regards to brominated flame retardants using handheld XRF.

    Science.gov (United States)

    Aldrian, Alexia; Ledersteger, Alfred; Pomberger, Roland

    2015-02-01

    This contribution is focused on the on-site determination of the bromine content in waste electrical and electronic equipment (WEEE), in particular waste plastics from television sets (TV) and personal computer monitors (PC) using a handheld X-ray fluorescence (XRF) device. The described approach allows the examination of samples in regards to the compliance with legal specifications for polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) directly after disassembling and facilitates the sorting out of plastics with high contents of brominated flame retardants (BFRs). In all, over 3000 pieces of black (TV) and 1600 pieces of grey (PC) plastic waste were analysed with handheld XRF technique for this study. Especially noticeable was the high percentage of pieces with a bromine content of over 50,000ppm for TV (7%) and PC (39%) waste plastics. The applied method was validated by comparing the data of handheld XRF with results obtained by GC-MS. The results showed the expected and sufficiently accurate correlation between these two methods. It is shown that handheld XRF technique is an effective tool for fast monitoring of large volumes of WEEE plastics in regards to BFRs for on-site measurements. PMID:25464945

  3. Computer simulation of the cluster destruction of stratospheric ozone by bromine

    Institute of Scientific and Technical Information of China (English)

    A.E.Galashev; O.R.Rakhmanova

    2012-01-01

    The interaction of (Br-)i(H2O)50-i,0≤i≤6 clusters with oxygen and ozone molecules is investigated by the method of molecular dynamics simulation.The ozone molecules as well as the bromine ions do not leave the cluster during the calculation of 25 ps.The ability of the cluster containing molecular oxygen to absorb the infrared (IR)radiation is reduced in the frequency range of 0 ≤ ω ≤ 3500 cm-1 when the number of the bromine ions in the cluster grows.The intensity of the Raman spectrum is not changed significantly when the Br-ions are added to the ozonecontaining system.The power of the emitted IR radiation is increased when the number of bromine ions grows in the oxygen-containing system.The data obtained in this study on the IR and the Raman spectra of the water clusters that contain ozone,oxygen,and Br-can be used to develop an investigation of the mechanisms of ozone depletion.

  4. Measurement and human exposure assessment of brominated flame retardants in household products from South China

    International Nuclear Information System (INIS)

    Brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs), and decabromodiphenyl ethane (DBDPE) were examined in household products in the Pearl River Delta, South China, including electronic appliances, furniture and upholstery, car interiors, and raw materials for electronics. The concentrations of PBDEs derived from penta-BDE mixture were much lower (<111 ng/g) than those for octa- and deca-BDE commercially derived PBDEs, with maximum values of 15,107 and 1,603,343 ng/g, respectively, in all the household products. Our findings suggest the recycling of old electronic products and their reuse might be also a potential important source of discontinued PBDEs to the environment. DBDPE was found in 20.0% of all the samples, ranging from 311 to 268,230 ng/g. PBDE congener profiles in both the household products and raw materials suggest that some less brominated BDEs in the environment may be derived from the decomposition of higher brominated PBDEs in PBDE-containing products in process of the manufacturing, use and/or recycling. Human exposure to PBDEs from household products via inhalation ranged from 175 to 612 pg/kg bw day, accounting for a small proportion of the total daily exposure via indoor inhalation. Despite the low deleterious risk associated with household products with regard to PBDEs, they are of special concern because of the relatively higher exposures observed for young children and further work is required.

  5. Computer simulation of the cluster destruction of stratospheric ozone by bromine

    International Nuclear Information System (INIS)

    The interaction of (Br−)i(H2O)50−i, 0 ≤ i ≤ 6 clusters with oxygen and ozone molecules is investigated by the method of molecular dynamics simulation. The ozone molecules as well as the bromine ions do not leave the cluster during the calculation of 25 ps. The ability of the cluster containing molecular oxygen to absorb the infrared (IR) radiation is reduced in the frequency range of 0 ≤ ω ≤ 3500 cm−1 when the number of the bromine ions in the cluster grows. The intensity of the Raman spectrum is not changed significantly when the Br− ions are added to the ozone-containing system. The power of the emitted IR radiation is increased when the number of bromine ions grows in the oxygen-containing system. The data obtained in this study on the IR and the Raman spectra of the water clusters that contain ozone, oxygen, and Br− can be used to develop an investigation of the mechanisms of ozone depletion

  6. Bromine recovery in residual solutions generated in the 15 N isotopic determination methodology (Rittenberg, 1946)

    International Nuclear Information System (INIS)

    The isotopic determination of 15 N (Rittenberg, 1946) is a methodology used in the Laboratory of Isotope Stable (CENA/USP). In this procedure, in the oxidation of nitrogen species for N2, solution of Li Br O is used, generating as residue 50 L y-1 of solution contends Li Br and Li Br O. Seeking to recover the bromine contained in that residue, very toxic substance, a special line was built composed by reaction balloons (1 and 2 liters), addition funnel, gas flow regulator and connections in glass. In the system proposed, after the acidification (sulfuric acid) of the alkaline residual solution, the liberated bromine (Br2) it was then dragged by flow of nitrogen and reacted with solution of LiOH. That reaction facilitated the production of Li Br O in solution (Efficiency = 82±2%), that was reused later on same analytic procedure. The high cost of the liquid bromine is another attractiveness that corroborates the employment of the developed procedure. They took place isotopic determinations using the recovered solutions and prepared, and the observed values didn't show statistical difference (T test of Student). The presented procedure is part of the Management Program of Chemical Residues of CENA/USP, which seeks to destine the residues of responsibility of the institution appropriately, forming professionals to the practices of environmental management. (author)

  7. A satellite based study of tropospheric bromine explosion events and their linkages to polar cyclone development

    Science.gov (United States)

    Blechschmidt, Anne-Marlene; Richter, Andreas; Burrows, John P.; Kaleschke, Lars; Strong, Kimberly; Theys, Nicolas; Weber, Mark; Zhao, Xiaoyi; Zien, Achim; Hodges, Kevin I.

    2016-04-01

    Intense, cyclone-like shaped plumes of tropospheric bromine monoxide (BrO) are regularly observed by the UV-vis satellite instruments GOME-2/MetOp-A and SCIAMACHY/Envisat over Arctic and Antarctic sea ice in polar spring. The plumes are associated with an autocatalytic chemical chain reaction involving tropospheric ozone depletion and initiated by the release of bromine from cold brine-covered ice or snow to the atmosphere. This influences atmospheric chemistry as it affects the oxidising capacity of the troposphere through OH production and may also influence the local weather/temperature of the polar atmosphere, as ozone is a major greenhouse gas. Here, we make combined use of satellite retrievals and numerical model simulations to study individual BrO plume cases in the polar atmosphere. In agreement with previous studies, our analysis shows that the plumes are often transported by high latitude cyclones, sometimes over several days despite the short atmospheric lifetime of BrO. Moreover, general characteristics of bromine explosion events linked to transport by polar weather systems, such as frequency, spatial distribution and favourable weather conditions are derived based on a new detection method. Our results show that BrO cyclone transport events are by far more common in the Antarctic than in the Arctic.

  8. Hydrogen Fluoride in the Local Universe

    Science.gov (United States)

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

    2015-01-01

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

  9. Polyvinylidene fluoride - a polymer as transducer material

    International Nuclear Information System (INIS)

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

  10. Lanthanum fluoride nanoparticles for radiosensitization of tumors

    Science.gov (United States)

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

    2016-03-01

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

  11. Luminescence in potential fluoride glass lasers

    International Nuclear Information System (INIS)

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

  12. Surface Snowpack Key to Bromine Activation in a Changing Arctic Environment

    Science.gov (United States)

    Pratt, Kerri; Custard, Kyle; Shepson, Paul; Douglas, Thomas; Pöhler, Denis; Stephan, General; Zielcke, Johannes; Simpson, William; Platt, Ulrich; von Glasow, Roland; Tanner, David; Huey, L. Gregory; Carlsen, Mark; Stirm, Brian

    2013-04-01

    Arctic sea ice is rapidly declining and transforming from a multiyear ice pack to thinner, more saline, seasonal ice, which has important implications for Arctic atmospheric composition. Following springtime polar sunrise, "ozone depletion events", attributed to bromine chemistry, lead to episodic decreases in lower tropospheric ozone concentrations to near zero, concurrent with mercury depletion and deposition. Despite our increasing understanding of the spatial variability of BrO and possible reaction pathways based on laboratory studies, important questions remain regarding the most efficient sources of and mechanisms for Arctic halogen activation. During the March-April 2012 BRomine, Ozone, and Mercury EXperiment (BROMEX) in Barrow, Alaska, outdoor chamber experiments with snow and ice samples were conducted. Ozone was added as the precursor oxidant, and the samples were investigated with and without ambient sunlight. Samples included first-year sea ice, brine icicles, several layers of snow above first-year sea ice, and seasonal snow above the tundra. Chemical ionization mass spectrometry was utilized to monitor Br2 production. Tundra snow and surface snow above sea ice produced the most Br2, with no production resulting from sea ice and basal snow directly above sea ice. Overall, the most efficient Br2 production was observed from snow samples characterized by lower pH and higher bromide/chloride ratios. Br2 was only observed in the presence of sunlight, indicating the role of snowpack photochemical reactions and the hydroxyl radical in its production. Br2 production via the surface snowpack explains previously-observed BrO enhancements above sea ice, as well as observations of inland tundra hotspots in measured BrO by aircraft-based nadir MAX-DOAS (Multi Axis-Differential Optical Absorption Spectroscopy) measurements, conducted during BROMEX. The findings indicate that atmospherically processed snow is likely a major source of Arctic bromine release, which

  13. Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

    Directory of Open Access Journals (Sweden)

    G. Giuffrida

    2012-12-01

    Full Text Available Over a 3-yr period, from 2006 to 2009, frequent scattered sunlight DOAS measurements were conducted at Mt. Etna at a distance of around 6 km downwind from the summit craters. During the same period and in addition to these measurements, volcanic observations were made by regularly visiting various parts of Mt. Etna. Here, results from these measurements and observations are presented and their relation is discussed. The focus of the investigation is the bromine monoxide/sulphur dioxide (BrO / SO2 ratio, and its variability in relation to volcanic processes. That the halogen/sulphur ratio can serve as a precursor or indicator for the onset of eruptive activity was already proposed by earlier works (e.g. Noguchi and Kamiya 1963; Menyailov, 1975; Pennisi and Cloarec, 1998; Aiuppa et al., 2002. However, there is still a limited understanding today because of the complexity with which halogens are released, depending on magma composition and degassing conditions. Our understanding of these processes is far from complete, for example of the rate and mechanism of bubble nucleation, growth and ascent in silicate melts (Carroll and Holloway, 1994, the halogen vapour-melt partitioning and the volatile diffusivity in the melt (Aiuppa et al., 2009. With this study we aim to add one more piece to the puzzle of what halogen/sulphur ratios might tell about volcanic activities. Our data set shows an increase of the BrO / SO2 ratio several weeks prior to an eruption, followed by a decline before and during the initial phase of eruptive activities. Towards the end of activity or shortly thereafter, the ratio increases to baseline values again and remains more or less constant during quiet phases. To explain the observed evolution of the BrO / SO2 ratio, a first empirical model is proposed. This model suggests that bromine, unlike chlorine and fluorine, is less soluble in the magmatic melt than sulphur. By using the DOAS method to determine SO2, we actually

  14. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium

    Indian Academy of Sciences (India)

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

    2009-12-01

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

  15. Fluoride Levels of Mothers' Breast Milk in Egypt

    Directory of Open Access Journals (Sweden)

    Ghada, Z A Soliman and Tamer M M Saad

    2012-01-01

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

  16. 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.

  17. Fluoride and lead adsorption on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Shuguang; LI Yanhui

    2004-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  1. Determination of fluoride with thorium nitrate by catalytic titration

    International Nuclear Information System (INIS)

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

  2. Spectrophotometric determination of fluorides in water with Hach equipment

    International Nuclear Information System (INIS)

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

    OpenAIRE

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

    2010-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2015-01-01

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

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

    OpenAIRE

    Vella, Alfred J.; Borg, Vincent

    1989-01-01

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

  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. Cerium fluoride crystals for calorimetry at LHC

    International Nuclear Information System (INIS)

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

  10. Further results on cerium fluoride crystals

    International Nuclear Information System (INIS)

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

  11. Further results on cerium fluoride crystals

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-08-15

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

  12. Chemical etching of polyvinylidene fluoride films

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-10-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  15. 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.

  16. Redox condition in molten fluoride salts Definition and control

    International Nuclear Information System (INIS)

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

  17. Physical and chemical properties of volatile ruthenium fluorides

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Shalin Shah

    2013-01-01

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

  19. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    OpenAIRE

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

    2010-01-01

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

  20. Corrosion behavior of zirconia in acidulated phosphate fluoride

    OpenAIRE

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

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were charac...

  1. Corrosion behavior of zirconia in acidulated phosphate fluoride

    OpenAIRE

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

    2016-01-01

    ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characteri...

  2. Fluoride Consumption and Its Impact on Oral Health

    OpenAIRE

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

    2011-01-01

    Objective. The purpose of this study was to evaluate caries and dental fluorosis among Mexican preschoolers and school-aged children in a non-endemic zone for fluorosis and to measure its biological indicators. Methods. DMFT, DMFS, dmft, dmfs, and CDI indexes were applied. Fluoride urinary excretion and fluoride concentrations in home water, table salt, bottled water, bottled drinks, and toothpaste were determined. Results. Schoolchildren presented fluorosis (CDI = 0.96) and dental caries (DM...

  3. Scientific Opinion on Dietary Reference Values for fluoride

    OpenAIRE

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

    2013-01-01

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

  4. Thermodynamic investigation of fluoride salts for nuclear energy production

    OpenAIRE

    Beilmann, Markus

    2013-01-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    OpenAIRE

    Pereira, J. Nunes

    2013-01-01

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

  7. 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.

  8. Polyacrylamide supported SPADNS-zirconium resin for fluoride removal

    International Nuclear Information System (INIS)

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

  9. 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.

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

    Science.gov (United States)

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

    2016-02-21

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

  11. 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...

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

    Directory of Open Access Journals (Sweden)

    Amouei A.I. PhD,

    2016-03-01

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

  13. EXPERIMENTAL STUDY AND NUMERICAL SIMULATION OF FLUORIDE IN SAND

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-mei; SU Bao-yu

    2006-01-01

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

  14. Production of HBR from bromine and steam for off-peak electrolytic hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Schlief, R.E.; Hanrahan, R.J.; Stoy, M.A. [Univ. of Florida, Gainesville, FL (United States)] [and others

    1995-09-01

    Progress is reported on the development of a renewable energy source based solar-electrolytic system for production of hydrogen and oxygen. It employs water, bromine, solar energy and supplemental electrical power. The concept is being developed by Solar Reactor Technologies, Inc., (SRT), with the U.S. Department of Energy (DOE). An overview of the nature and objectives of this program is provided here, and technical progress made during the first (three-month) performance period of the Phase I work effort is reported. The SRT concept entails (1) absorption of concentrated solar radiation by bromine vapor Br{sub 2(g)} in a high-temperature reactor producing Br{sub (g)} atoms, (2) reaction of Br{sub (g)} with water yielding hydrogen bromide (HBr), and (3) electrolysis of stored hydrogen bromide for production of H{sub 2(g)} and recovery of Br{sub 2(I)}. Incorporation of solar radiation in the primary photochemical step (1) reduces by 50 - 70% the electrical power required to split water. The SRT concept is very attractive from an economic viewpoint as well. The reversible fuel cell, employed in the SRT electrolysis concept is capitalized via its use in load leveling by the utility. A 1 kW solar reactor was designed and constructed during the first three-month performance period by SRT personnel at the University of Florida, Gainesville. It was employed in taking survey data of the reaction between bromine and steam at temperatures between 900 and 1300 K. This reaction was run under purely thermal conditions, i.e. in the absence of solar photons. The experimental data are reported and interpreted employing concomitant thermodynamic calculations. The anticipated improvement is discussed briefly as well as the effect of a photochemical boost to the reaction. The amount of this enhancement will be studied in the next three month performance period.

  15. Molecular simulations and density functional theory calculations of bromine in clathrate hydrate phases

    International Nuclear Information System (INIS)

    Bromine forms a tetragonal clathrate hydrate structure (TS-I) very rarely observed in clathrate hydrates of other guest substances. The detailed structure, energetics, and dynamics of Br2 and Cl2 in TS-I and cubic structure I (CS-I) clathrate hydrates are studied in this work using molecular dynamics and quantum chemical calculations. X-ray diffraction studies show that the halogen-water–oxygen distances in the cages of these structures are shorter than the sum of the van der Waals radii of halogen and oxygen atoms. This suggests that the stabilizing effects of halogen bonding or other non-covalent interactions (NCIs) may contribute to the formation of the unique tetragonal bromine hydrate structure. We performed molecular dynamics simulations of Br2 and Cl2 clathrate hydrates using our previously developed five-site charge models for the dihalogen molecules [Dureckova et al. Can. J. Chem. 93, 864 (2015)] which reproduce the computed electrostatic potentials of the dihalogens and account for the electropositive σ-hole of the halogen bond donor (the dihalogen). Analysis of the radial distribution functions, enthalpies of encapsulation, velocity and orientation autocorrelation functions, and polar angle distributions are carried out for Br2 and Cl2 guests in various cages to contrast the properties of these guests in the TS-I and CS-I phases. Quantum chemical partial geometry optimizations of Br2 and Cl2 guests in the hydrate cages using the M06-2X functional give short halogen-water distances compatible with values observed in X-ray diffraction experiments. NCI plots of guest-cage structures are generated to qualitatively show the relative strength of the non-bonding interactions between dihalogens and water molecules. The differences between behaviors of Br2 and Cl2 guests in the hydrate cages may explain why bromine forms the unique TS-I phase

  16. Trophic transfer of naturally produced brominated aromatic compounds in a Baltic Sea food chain.

    Science.gov (United States)

    Dahlgren, Elin; Lindqvist, Dennis; Dahlgren, Henrik; Asplund, Lillemor; Lehtilä, Kari

    2016-02-01

    Brominated aromatic compounds (BACs) are widely distributed in the marine environment. Some of these compounds are highly toxic, such as certain hydroxylated polybrominated diphenyl ethers (OH-PBDEs). In addition to anthropogenic emissions through use of BACs as e.g. flame retardants, BACs are natural products formed by marine organisms such as algae, sponges, and cyanobacteria. Little is known of the transfer of BACs from natural producers and further up in the trophic food chain. In this study it was observed that total sum of methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and OH-PBDEs increased in concentration from the filamentous red alga Ceramium tenuicorne, via Gammarus sp. and three-spined stickleback (Gasterosteus aculeatus) to perch (Perca fluviatilis). The MeO-PBDEs, which were expected to bioaccumulate, increased in concentration accordingly up to perch, where the levels suddenly dropped dramatically. The opposite pattern was observed for OH-PBDEs, where the concentration exhibited a general trend of decline up the food web, but increased in perch, indicating metabolic demethylation of MeO-PBDEs. Debromination was also indicated to occur when progressing through the food chain resulting in high levels of tetra-brominated MeO-PBDE and OH-PBDE congeners in fish, while some penta- and hexa-brominated congeners were observed to be the dominant products in the alga. As it has been shown that OH-PBDEs are potent disruptors of oxidative phosphorylation and that mixtures of different congener may act synergistically in terms of this toxic mode of action, the high levels of OH-PBDEs detected in perch in this study warrants further investigation into potential effects of these compounds on Baltic wildlife, and monitoring of their levels. PMID:26517387

  17. The measurement of bromine monoxide from Fairbanks, AK and comparison with OMI/AURA

    Science.gov (United States)

    Mount, G. H.; Spinei, E.; Herman, J. R.; Cede, A.; Abuhassan, N.; Simpson, W. R.; McPeters, R. D.; Bhartia, P. K.; Johnson, B. J.; Salawitch, R. J.; Canty, T. P.; Chance, K.; Kurosu, T. P.; Suleiman, R. M.

    2011-12-01

    Enhanced column bromine monoxide in the Arctic has been observed by satellites for some time and is related to bromine "hotspots" that result in nearly complete removal of surface ozone in springtime. Salawitch et al. (2010) have demonstrated that these enhancements show little relation, at times, to satellite-enhanced column BrO. Several recent studies have shown that closure of the budget for total column BrO is achieved by summing observed tropospheric partial column BrO with a calculated stratospheric partial column that accounts for the supply of 7 ppt of Bry from natural, short-lived biogenic bromocarbons to the lowermost stratosphere. However, the burden of Bry in the upper stratosphere in these studies, 26 ppt, is at the upper limit of Bry levels inferred from upper stratospheric BrO. A ground-based NASA-sponsored field campaign was held in Fairbanks, AK in March and April 2011 to measure bromine monoxide and other trace gases by direct sun and multi-axis scattered skylight in combination with daily ozonesondes and OMI/AURA satellite data of BrO. The tropospheric contribution to column BrO should be near zero at this time/location. The campaign was therefore focused on defining the stratospheric BrO burden and evaluating the accuracy of total column BrO reported by OMI. The comparison of the ground-based BrO data with the OMI data is reported. Additionally, the DOAS derivation of BrO is explored using various spectral fitting windows and an error budget compiled showing the sensitivity of the deduced BrO vertical column with instrument-dependent spectral window.

  18. Thermodynamic properties of bromine fluorene derivatives: An experimental and computational study

    International Nuclear Information System (INIS)

    Highlights: • Vapour pressures of two bromine derivatives of fluorene were measured. • Combustion energies of two bromine derivatives of fluorene were determined. • Standard molar ΔH, ΔS and ΔG of sublimation and vapourisation were derived. • Standard molar ΔH, ΔS and ΔG of formation in crystal and gas phases were calculated. • Gas phase ΔH of formation was also estimated by quantum chemical calculations. - Abstract: This report presents a comprehensive experimental and computational study of the thermodynamic properties of two bromine fluorene derivatives: 2-bromofluorene and 2,7-dibromofluorene. The standard (p° = 0.1 MPa) molar enthalpies of formation in the crystalline phase of these compounds were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by rotating bomb combustion calorimetry. The vapour pressures of the crystalline phase of the two compounds were measured using the Knudsen effusion method and a static method that has also been used to measure the liquid vapour pressures of 2-bromofluorene. From these results the standard molar enthalpies, entropies and Gibbs energies of sublimation of the two compounds studied and of vapourisation of 2-bromofluorene were derived. The enthalpies and temperatures of fusion were determined from DSC experiments. Derived results of standard enthalpies and Gibbs energies of formation, in both gaseous and crystalline phases, were compared with the ones reported in the literature for fluorene. The experimental values of the gas-phase enthalpies of formation of each compound were compared with estimates based on density functional theory calculations using the B3LYP hybrid exchange–correlation energy functional with the 6-311++G(d,p) basis set

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

    Science.gov (United States)

    Grandjean, P; Hørder, M; Thomassen, Y

    1990-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Hayacibara Mitsue Fujimaki

    2004-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    梁鹏; 张艺; 汪东风; 徐莹; 罗斓

    2013-01-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

  3. Removal of fluoride from water using aluminium containing compounds

    Institute of Scientific and Technical Information of China (English)

    M. Karthikeyan; K. P. Elango

    2009-01-01

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

  4. With bromine against mercury. Reduction of emission of mercury from combustion gases by 90 % minimally; Mit Brom gegen Quecksilber. Hg-Emissionen aus Verbrennungsabgasen um mindestens 90 % senken

    Energy Technology Data Exchange (ETDEWEB)

    Kanefke, Rico [Currenta GmbH und Co. OHG, Leverkusen (Germany)

    2009-01-15

    Emission of mercury is a global problem. If mercury once arrived into the environment, it remains there for a long period of time and increasingly becomes a strain for humans. In particular, the combustion of coal releases mercury. Under this aspect, the author of the contribution under consideration reports on a new procedure to an almost complete separation of mercury from exhaust gases. The complete oxidation of mercury in the flue gas is the basis to the improved separation of mercury. During bromination of mercury in the cooling down flue gas of boilers, mercury bromide is developed. Bromine is given as a bromine compound such as calcium bromide to the fuel such as coal. At temperatures greater than 1,000 Celsius, at first hydrogen bromide is developed which is converted to bromine by means of the bromine-Deacon-process during cooling. At temperatures below 100 Celsius, the formed bromine reacts with sulphur dioxide so that bromine is available in the entire reaction vessel for the oxidation of mercury. With comparable amount of SO{sub 2}, the oxidation of mercury with bromine is at least 25 times more efficient than the oxidation with chlorine. After this, mercury bromide is separated in the wet scrubber and precipitated during the treatment of rinsing water. Then the resulting mercury sulphide is separated as a filter cake from the water and spent on the dump. Thus, mercury is withdrawn from the atmospheric mercury cycle.

  5. Assessment of PCDD/F and PBDD/F Emissions from Coal-fired Power Plants during Injection of Brominated Activated Carbon for Mercury Control

    Science.gov (United States)

    The effect of the injection of brominated powdered activated carbon (Br-PAC) on the emission of brominated and chlorinated dioxins and furans in coal combustion flue gas has been evaluated. The tests were performed at two U.S. Department of Energy (DOE) demonstration sites where ...

  6. Reaction modelling of Iron Oxide Bromination in the UT-3 thermochemical cycle for Hydrogen production from water

    International Nuclear Information System (INIS)

    Analysis modelling of the iron oxide bromination had been carried out using experiment data from the iron oxide bromination in the UT-3 thermochemical cycle. Iron oxide in the form of pellets were made of the calcination of the mixture of iron oxide, silica, graphite and cellulose at 1473 K. Thermobalance reactor was used to study the kinetic reactions of the iron oxide bromination at a temperature of 473 K for 2 - 6 hours. The data collected from the experiments were used as input for the common models. However, none of these models could not explain the result of the experiments. A new model, a combination of two kinetic reactions : exposed particle and coated particle was created and worked successfully

  7. Origin of bromine in ancient sutras of the Otani collection. PIXE application to preservation of cultural assets

    International Nuclear Information System (INIS)

    Some small fragments of rag paper - made more than a thousand and a few hundred years ago, and excavated at Turfan, west of China by the Otani-expedition dispatched there during the late Meiji and the Taisho eras - were measured by PIXE. Bromine was highly detected in all of these ancient fragments and modern paper samples that had been placed together with these Turfan manuscripts. In other paper samples, bromine could not be detected (H+, 4 MeV, 50 μC and H+, 2 MeV, 100 μC) and their average concentration was about 1.1 ppm (S.D. = 1.11 ppm, N = 15, 0.3 - 3.4 ppm). The bromine contamination of ancient sutras is mainly caused by larvicide of methyl bromide, and the observation suggests that the ancient manuscripts might be spoiled gradually by agricultural chemicals for protecting them from vermin. (author)

  8. Enriched concentrations of bromine, chlorine, and iodine in urban rainfall as determined by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Concentrations of bromine, chlorine and iodine were determined in bulk rain as part of a detailed urban monitoring program. Instrumental neutron activation gives simultaneous non-destructive analysis of these halogens with detection limits of 2, 30 and 1 ng/g for bromine, chlorine, and iodine, respectively. Results for enrichment factor calculations based on crustal, seawater and lake water reference elements were somewhat contradictory. Elemental ratios of Br/Cl, I/Cl, Br/Pb, and Cl/Pb, together with an analysis of chlorine in urban surface materials, support the suggestions that local anthropogenic sources may cause the high bromine and chlorine concentrations observed in urban precipitation while fractionation from an oceanic source is likely responsible for high iodine concentrations. (author)

  9. Magnetically enhanced triode etching of large area silicon membranes in a molecular bromine plasma

    International Nuclear Information System (INIS)

    The optimization of a process for etching 125 mm silicon membranes formed on 150 mm wafers and bonded to Pyrex rings is discussed. A magnetically enhanced triode etching system was designed to provide an intense, remote plasma surrounding the membrane while, at the same time, suppressing the discharge over the membrane itself. For the optimized molecular bromine process, the silicon etch rate is 40 nm/min and the selectivity relative to SiO2 is 160:1. 14 refs., 6 figs

  10. Neutron Activation Analysis of Vanadium, Copper, Zinc, Bromine and Iodine in Pyura Microcosmus

    International Nuclear Information System (INIS)

    Most of the tunicates seem to accumulate vanadium more energetically than other marine organisms. However, there is a very great variation within the group. Maximum amounts of vanadium were found in the Ascididae family whereas in some species of the Pyuridae family vanadium was apparently absent. This paper describes the simple and rapid determination by activation analysis of vanadium, copper, zinc, bromine and iodine in Pyura microcosmus, a species of the Pyuridae family. The same elements were also investigated in the environmental sea-water. Samples of P. microcosmus and sea-water were collected from a point about 15 m below the surface in the Saronic Gulf near Athens. All irradiations of samples and standards were carried out with the DEMOCRITUS Reactor of the Nuclear Research Centre of Greece, at a neutron flux of 2 x 1011 n/cm2s. The time of irradiation with the pneumatic transfer system ranged from 1 to 25 min, depending on the element being determined. After irradiation and addition of inactive carriers, the radioisotopes of interest were isolated by fast radiochemical procedures based on solvent extraction techniques. Vanadium and copper were extracted as cupferrates into chloroform, and zinc was extracted with 8% methyldioctylamine into trichloroethylene. Bromine and iodine were distilled first and then separated from each other by selective redox and extraction procedures. The photopeak areas of 52V, 64Cu, 69mZn, 82Br and 128I were measured by means of a multichannel analyser and compared with those of standards of the above radionuclides processed in the same manner. After irradiation the time to complete the analysis ranged from 5 to 35 min depending on the element being determined. The quantities of the elements determined in P. microcosmus, expressed in micrograms per gram of dry matter, were: vanadium 1.0, copper 7.5, iodine 14.1, bromine 406 and zinc 702. The per cent concentration of the same elements found in the sea-water was as follows

  11. SYNTHESIS AND GREEN BROMINATION OF SOME CHALCONES AND THEIR ANTIMICROBIAL SCREENING

    Directory of Open Access Journals (Sweden)

    Mayur R. Adokar

    2013-04-01

    Full Text Available Chalcones are the versatile molecules having the structural flexibility which permits structural transformations into flavonoids, flavanones, pyrazoles, oxazoles, pyrimidines etc. Changes in their structure have offered the development of new medicinal agents having improved pharmacological potency. Their derivatives have attracts increasing attention due to numerous pharmacological potential. In the present communication we report the synthesis of chalcones from various acetophenone derivatives with different aromatic aldehydes and green chemistry approach to their bromination with the help of Tetrabutylammonium Tribromide (TBATB. All the synthesized chalcone dibromides were screened for their antimicrobial activity against Aspergillus flavus, Rhizopus sp., Fusarium solani and Aspergillus niger.

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

    OpenAIRE

    Stephen Peckham; Niyi Awofeso

    2014-01-01

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

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

    OpenAIRE

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

    2016-01-01

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

  14. 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

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

    Science.gov (United States)

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

    2015-01-01

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

  16. Levels of persistent fluorinated, chlorinated and brominated compounds in human blood collected in Sweden in 1997-2000

    Energy Technology Data Exchange (ETDEWEB)

    Lindstroem, G.; Kaerrman, A.; Bavel, B. van [MTM Research Centre, Oerebro Univ. (Sweden); Hardell, L. [Dept. of Oncology, Univ. Hospital, Oerebro (Sweden); Hedlund, B. [Environmental Monitoring Section, Swedish EPA, Stockholm (Sweden)

    2004-09-15

    Levels of persistent fluorinated, chlorinated and brominated compounds in blood collected from the Swedish population have been determined in connection with several exposure and monitoring studies at the MTM Research Centre. A data base with 631 individual congener specific measurements on halogenated POPs such as dioxins, PCBs, HCB, DDE, chlordanes, PBDEs and PFAs including information on residency, age, BMI, diet, occupation, number of children, smoking habits, immunological status etc. has been compiled from samples collected between 1994 and 2004. A brief overview focusing on levels of some persistent chlorinated, brominated and fluorinated, compounds in blood collected in a background population group (n=83) in 1997-2000 is given here.

  17. Price Wars and the Stability of Collusion: A Study of the Pre-World War I Bromine Industry

    OpenAIRE

    Margaret Levenstein

    1993-01-01

    Bromine producers colluded to raise prices and profits during most of the period between 1885 and 1914. Collusion was punctuated by price wars in which prices fell sharply. The characteristics of these price wars are compared with those in the Green-Porter and Abreu- Pearce-Stachetti models. Some of the bromine price wars resulted from the imperfect monitoring problems in these models. Those price wars were short and mild. More severe price wars were part of a bargaining process, in which fir...

  18. Synchrotron X-ray fluorescence studies of a bromine-labelled cyclic RGD peptide interacting with individual tumor cells

    International Nuclear Information System (INIS)

    The first example of synchrotron X-ray fluorescence imaging of cultured mammalian cells in cyclic peptide research is reported. The study reports the first quantitative analysis of the incorporation of a bromine-labelled cyclic RGD peptide and its effects on the biodistribution of endogenous elements (for example, K and Cl) within individual tumor cells. The first example of synchrotron X-ray fluorescence imaging of cultured mammalian cells in cyclic peptide research is reported. The study reports the first quantitative analysis of the incorporation of a bromine-labelled cyclic RGD peptide and its effects on the biodistribution of endogenous elements (for example, K and Cl) within individual tumor cells

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

    Science.gov (United States)

    Shannon, I. L.

    1975-01-01

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

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

    OpenAIRE

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

    2016-01-01

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

  1. Characterization of cerium fluoride nanocomposite scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  2. Magnetic separation of uranium from magnesium fluoride

    International Nuclear Information System (INIS)

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

  3. Characterization of cerium fluoride nanocomposite scintillators

    International Nuclear Information System (INIS)

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

  4. Thermodynamic data for treatment of fluoride

    International Nuclear Information System (INIS)

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

  5. Magnetic separation of uranium from magnesium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Hoegler, J.M.

    1987-01-01

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

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

    International Nuclear Information System (INIS)

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

  7. Occurrence and risk assessment of organophosphorus and brominated flame retardants in the River Aire (UK)

    International Nuclear Information System (INIS)

    This study presents the occurrence and risk of PBDEs, new brominated and organophosphorus flame retardants along a river affected by urban and industrial pressures (River Aire, UK). Tris(2-choroethyl) phosphate (TCEP), tris(2-chloro-1-methylethyl) phosphate (TCPP), tris[2-chloro-1-(chloromethyl)ethyl] phosphate (TDCP) and triphenyl phosphate (TPhP) were detected in all samples, with TCPP present at the highest concentrations, ranging from 113 to 26 050 ng L-1. BDE-209 was detected in most of the sampled sites, ranging from 17 to 295 ng L−1, while hexabromobenzene (HBB) and pentabromoethyl benzene (PBEB) were seldom detected. A risk quotients based on predicted no effect concentrations (PNEC) and flame retardants water concentration proved significant risk for adverse effects for algae, Daphnia and fish in sites close to industrial and urban sewage discharges. This study provides a protocol for the risk estimation of priority and new generation flame retardants based on river concentrations and toxicological values. -- Highlights: •Brominated and organophosphorus flame retardants were monitored in River Aire (UK). •BDE-209 and organophosphorus flame retardants were detected at high concentrations. •A risk assessment was performed based on water concentration and acute toxicity data. •Low to significant risk for adverse effects was observed for algae, fish and Daphnia. -- Organophosphorus flame retardants and BDE-209 were detected at high concentrations along River Aire (UK) and a risk assessment indicated significant risk for adverse effects to aquatic organisms

  8. Iodine-123 and bromine-75 production and development program at Juelich

    International Nuclear Information System (INIS)

    The iodine-123 and bromine-75 production and development program at the Nuclear Research Center in Juelich as of 1982 is described, and examples of recent 123I- and 75Br-analogue tracers that have been developed to the level of clinical trial are given. Iodine-123 is produced via the 127I(d,6n)123Xe → 123I process and by the 124Te(p,2n)123I and 122Te(d,n)123I reactions. These production methods are critically reviewed. Bromine-75-labeled benzodiazenes have been prepared for in vivo mapping of benzodiazepine receptor sites. The 7-(75Br)-5-(2-fluorophenyl)-1-methyl-1,3-dihydro-2H-1,4-benzodiazepine-2-one (BFB) was prepared with a specific activity of > 104 Ci/mmole. Finally, preparation and applications of the halogenated amino acid L-3-(123I)-iodo-α-methyltyrosine (IMT) and the analogous 75Br compound (BMT) are reported. Both IMT and BMT have been successfully applied for pancreas imaging and tomography, and IMT has been used for imaging both melanotic and amelanotic malignant melanoma of the eye

  9. Brominated diphenyl ethers in the sediments, porewater, and biota of the Chesapeake Bay, USA

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K.; Klosterhaus, S.; Liebert, D.; Stapleton, H. [Maryland Univ., Solomons, MD (United States)

    2004-09-15

    Levels of brominated diphenyl ethers (BDEs) are rapidly increasing in the environment, and in a short time these chemicals have evolved from 'emerging contaminants' to globally-distributed organic pollutants. Recent research demonstrates BDEs are sufficiently stable to be transported long distances in the environment and to accumulate in higher trophic levels. Photolysis and metabolism appear to be dominant loss processes for the parent compounds, generating a variety of lower brominated diphenyl ethers, hydroxylated metabolites, and other products. BDEs are hydrophobic, and therefore their transport in aquatic systems is likely controlled by sorption to sediments and perhaps exchange across the air-water interface. To date, few studies have examined the geochemistry of BDEs in natural waters. In this paper, we review our recent measurements of BDEs in the Chesapeake Bay, a shallow, productive estuary in eastern North America. We focus on the distribution of BDE congeners sediment, porewater, and in faunal benthos along a contamination gradient downstream from a wastewater treatment plant and on the spatial distribution of BDEs in bottom-feeding and pelagic fish species.

  10. Levelized cost of energy and sensitivity analysis for the hydrogen-bromine flow battery

    Science.gov (United States)

    Singh, Nirala; McFarland, Eric W.

    2015-08-01

    The technoeconomics of the hydrogen-bromine flow battery are investigated. Using existing performance data the operating conditions were optimized to minimize the levelized cost of electricity using individual component costs for the flow battery stack and other system units. Several different configurations were evaluated including use of a bromine complexing agent to reduce membrane requirements. Sensitivity analysis of cost is used to identify the system elements most strongly influencing the economics. The stack lifetime and round-trip efficiency of the cell are identified as major factors on the levelized cost of electricity, along with capital components related to hydrogen storage, the bipolar plate, and the membrane. Assuming that an electrocatalyst and membrane with a lifetime of 2000 cycles can be identified, the lowest cost market entry system capital is 220 kWh-1 for a 4 h discharge system and for a charging energy cost of 0.04 kWh-1 the levelized cost of the electricity delivered is 0.40 kWh-1. With systems manufactured at large scales these costs are expected to be lower.

  11. Dissolution of brominated epoxy resins by dimethyl sulfoxide to separate waste printed circuit boards.

    Science.gov (United States)

    Zhu, Ping; Chen, Yan; Wang, Liangyou; Qian, Guangren; Zhang, Wei Jie; Zhou, Ming; Zhou, Jin

    2013-03-19

    Improved methods are required for the recycling of waste printed circuit boards (WPCBs). In this study, WPCBs (1-1.5 cm(2)) were separated into their components using dimethyl sulfoxide (DMSO) at 60 °C for 45 min and a metallographic microscope was used to verify their delamination. An increased incubation time of 210 min yielded a complete separation of WPCBs into their components, and copper foils and glass fibers were obtained. The separation time decreased with increasing temperature. When the WPCB size was increased to 2-3 cm(2), the temperature required for complete separation increased to 90 °C. When the temperature was increased to 135 °C, liquid photo solder resists could be removed from the copper foil surfaces. The DMSO was regenerated by rotary decompression evaporation, and residues were obtained. Fourier transform infrared spectroscopy (FT-IR), thermal analysis, nuclear magnetic resonance, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to verify that these residues were brominated epoxy resins. From FT-IR analysis after the dissolution of brominated epoxy resins in DMSO it was deduced that hydrogen bonding may play an important role in the dissolution mechanism. This novel technology offers a method for separating valuable materials and preventing environmental pollution from WPCBs. PMID:23398278

  12. Stable bromine isotopic composition of methyl bromide released from plant matter

    Science.gov (United States)

    Horst, Axel; Holmstrand, Henry; Andersson, Per; Thornton, Brett F.; Wishkerman, Asher; Keppler, Frank; Gustafsson, Örjan

    2014-01-01

    Methyl bromide (CH3Br) emitted from plants constitutes a natural source of bromine to the atmosphere, and is a component in the currently unbalanced global CH3Br budget. In the stratosphere, CH3Br contributes to ozone loss processes. Studies of stable isotope composition may reduce uncertainties in the atmospheric CH3Br budget, but require well-constrained isotope fingerprints of the source end members. Here we report the first measurements of stable bromine isotopes (δ81Br) in CH3Br from abiotic plant emissions. Incubations of both KBr-fortified pectin, a ubiquitous cell-stabilizing macromolecule, and of a natural halophyte (Salicornia fruticosa), yielded an enrichment factor (ε) of -2.00 ± 0.23‰ (1σ, n = 8) for pectin and -1.82 ± 0.02‰ (1σ, n = 4) for Salicornia (the relative amount of the heavier 81Br was decreased in CH3Br compared to the substrate salt). For short incubations, and up to 10% consumption of the salt substrate, this isotope effect was similar for temperatures from 30 up to 300 °C. For longer incubations of up to 90 h at 180 °C the δ81Br values increased from -2‰ to 0‰ for pectin and to -1‰ for Salicornia. These δ81Br source signatures of CH3Br formation from plant matter combine with similar data for carbon isotopes to facilitate multidimensional isotope diagnostics of the CH3Br budget.

  13. Synthesis of α-Bromine- Terminated Polystyrene Macroinitiator and Its Initiation of MMA Polymerization by ATRP

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the present paper the synthesis of block copolymers via the transformation from living anionic polymerization (LAP) to atom transfer radical polymerization (ATRP) was described. Α-Bromine-terminated polystyrenes(PStBr) in the LAP step was prepared by using n-BuLi as initiator, tetrahydrofuran (THF) as the activator, α-methylstyrene (α-MeSt) as the capping group and liquid bromine (Br2) as the bromating agent. The effects of reaction conditions such as the amounts of α-MeSt, THF, and Br2 as well as molecular weight of polystyrene on the bromating efficiency (BE) and coupling extent (CE) were examined. The present results show that the yield of PStBr obtained was more than 93.8% and the coupling reaction was substantially absent. PStBr was further used as the macroinitiator in the polymerization of methyl-methacrylate(MMA) in the presence of copper(Ⅰ) halogen and 2,2-bipyridine(bpy) complexes. It was found that the molecular weight of the resulted PSt-b-PMMA increased linearly with the increase of the conversion of MMA and the polydispersity was 1.2-1.6. The structures of PStBr and P(St-b-MMA) were characterized by 1H NMR spectra.

  14. Ultrafast optical limiting properties and transient dynamics of symmetrical phenoxazinium bromine salt

    Science.gov (United States)

    Xiao, Zhengguo; Ge, Jianfeng; Li, Zhongguo; Wu, Xingzhi; Fang, Yu; Shi, Guang; Zhang, Xueru; Wang, Yuxiao; Song, Yinglin

    2015-12-01

    A symmetrical phenoxazinium bromine salt with resonant D-π-D structure was prepared and spectroscopically characterized. The ultrafast nonlinear optical (NLO) response of the compound dissolved in DMF was investigated using open aperture Z-scan method with 190 fs laser pulses at 515 nm. And the photo-physical dynamics of the compound was studied using transient absorption spectra at femtosecond time regime. The titled sample showed strong reverse saturable absorption (RSA) at 515 nm. Transient absorption results demonstrated that the compound exhibited RSA signals at 478-580 nm and SA signals at 600-780 nm. A simplified three-energy-level model was used to determine the photo-physical parameters. And the excited-state lifetime was evaluated to be around one nanosecond. Our results show that the phenoxazinium bromine salt has a large ratio of singlet excited-state absorption cross-section to that of ground state cross-section (18.7), indicating it is a candidate material for future ultrafast optical limiters.

  15. Natural solar photolysis of total organic chlorine, bromine and iodine in water.

    Science.gov (United States)

    Abusallout, Ibrahim; Hua, Guanghui

    2016-04-01

    Municipal wastewater has been increasingly used to augment drinking water supplies due to the growing water scarcity. Wastewater-derived disinfection byproducts (DBPs) may negatively affect the aquatic ecosystems and human health of downstream communities during water reuse. The objective of this research was to determine the degradation kinetics of total organic chlorine (TOCl), bromine (TOBr) and iodine (TOI) in water by natural sunlight irradiation. Outdoor solar photolysis experiments were performed to investigate photolytic degradation of the total organic halogen (TOX) formed by fulvic acid and real water and wastewater samples. The results showed that TOX degradation by sunlight irradiation followed the first-order kinetics with half-lives in the range of 2.6-10.7 h for different TOX compounds produced by fulvic acid. The TOX degradation rates were generally in the order of TOI > TOBr ≅ TOCl(NH2Cl) > TOCl(Cl2). High molecular weight TOX was more susceptible to solar photolysis than corresponding low molecular weight halogenated compounds. The nitrate and sulfite induced indirect TOX photolysis rates were less than 50% of the direct photolysis rates under the conditions of this study. Fulvic acid and turbidity in water reduced TOX photodegradation. These results contribute to a better understanding of the fate of chlorinated, brominated and iodinated DBPs in surface waters. PMID:26841230

  16. Novel Spectrophotometric Method for Determination of Macro-paracetamol via Reaction with Bromine

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The reaction between Br2 and paracetamol(p-AAP) leads to the formation of a coloured product, which can be used for spectrophotometric determination of the p-AAP content in its pure form and in different pharmaceutical preparations with p-AAP. The stoichiometric composition of the reaction was found to be n(p-AAP)∶n(bromine)=1∶3. The effects of pH and time on the spectra of p-AAP-bromine redox reaction product were studied. The interference of different additives on the measured spectra of the obtained product was also studied. The results obtained by the present method were compared with those obtained by the standard method. The F- and t- test values were calculated for both of the applied procedures and they met a confidence level of 99%. The proposed procedure actually needs no separation of these drugs from their sources before analysis and was unaffected by interference of other phenolic compounds. The proposed method is simpler and faster than the repoeted ones.

  17. Selected chlorobornanes, polychlorinated naphthalenes and brominated flame retardants in Bjornoya (Bear Island) freshwater biota

    International Nuclear Information System (INIS)

    Levels of selected sparsely investigated persistent organic pollutants (POPs) have been measured in organisms from two Arctic lakes on Bjornoya (Bear Island). Elevated levels of chlorobornanes (CHBs) (up to 46.7 ng/g wet weight=ww), polybrominated diphenyl ethers (PBDEs) (up to 27.2 ng/g ww), polybrominated biphenyls (PBBs) (up to 1.1 ng/g ww) and polychlorinated naphthalenes (PCNs, only 4 congeners) (up to 62.7 pg/g ww), were measured in biota from Lake Ellasjoen. In Lake Oyangen, located only 5 km north of Ellasjoen, levels of these contaminants were significantly lower. δ15N-values were 7-10%o higher in organisms from Ellasjoen as compared to Oyangen. This is attributed to biological inputs related to seabird activities. The present study illustrates that contaminants such as CHBs, brominated flame retardants and PCNs accumulate in the Ellasjoen food web in a manner similar to PCBs and conventional organochlorine pesticides. Transport mechanisms that control PCB and DDT distributions, i.e. atmospheric long-range transport and biotransport by seabirds, are also relevant for the contaminants investigated in the present study. - Elevate levels of chlorobornanes, polychlorinated naphthalenes and brominated flame retardants have been measured in biota from a Norwegian Arctic lake

  18. Development of Zinc/Bromine Batteries for Load-Leveling Applications: Phase 2 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    CLARK,NANCY H.; EIDLER,PHILLIP

    1999-10-01

    This report documents Phase 2 of a project to design, develop, and test a zinc/bromine battery technology for use in utility energy storage applications. The project was co-funded by the U.S. Department of Energy Office of Power Technologies through Sandia National Laboratories. The viability of the zinc/bromine technology was demonstrated in Phase 1. In Phase 2, the technology developed during Phase 1 was scaled up to a size appropriate for the application. Batteries were increased in size from 8-cell, 1170-cm{sup 2} cell stacks (Phase 1) to 8- and then 60-cell, 2500-cm{sup 2} cell stacks in this phase. The 2500-cm{sup 2} series battery stacks were developed as the building block for large utility battery systems. Core technology research on electrolyte and separator materials and on manufacturing techniques, which began in Phase 1, continued to be investigated during Phase 2. Finally, the end product of this project was a 100-kWh prototype battery system to be installed and tested at an electric utility.

  19. Tropospheric Bromine Chemistry: Implications for Present and Pre-industrial Ozone and Mercury

    Science.gov (United States)

    Parella, J. P.; Jacob, D. J.; Liang, Q.; Zhang, Y.; Mickley, L. J.; Miller, B.; Evans, M. J.; Yang, X.; Pyle, J. A.; Theys, N.; VanRoozendael, M.

    2012-01-01

    We present a new model for the global tropospheric chemistry of inorganic bromine (Bry) coupled to oxidant-aerosol chemistry in the GEOS-Chem chemical transport model (CTM). Sources of tropospheric Bry include debromination of sea-salt aerosol, photolysis and oxidation of short-lived bromocarbons, and transport from the stratosphere. Comparison to a GOME-2 satellite climatology of tropospheric BrO columns shows that the model can reproduce the observed increase of BrO with latitude, the northern mid-latitudes maximum in winter, and the Arctic maximum in spring. This successful simulation is contingent on the HOBr + HBr reaction taking place in aqueous aerosols and ice clouds. Bromine chemistry in the model decreases tropospheric ozone mixing ratios by mercury against oxidation by Br. This suggests that historical anthropogenic mercury emissions may have mostly deposited to northern mid-latitudes, enriching the corresponding surface reservoirs. The persistent rise in background surface ozone at northern mid-latitudes during the past decades could possibly contribute to the observations of elevated mercury in subsurface waters of the North Atlantic.

  20. Small mammal populations in Maryland meadows during four years of herbicide (Brominal? ) applications

    Science.gov (United States)

    Clark, D.R., Jr.; Moulton, C.A.; Hines, J.E.; Hoffman, D.J.

    1996-01-01

    The herbicide Brominal? was applied at the recommended rate to one plot in each of three paired 0.6-ha plots; the other three plots were used as controls. Plots were sprayed once in the fall of 1988 and 1989 and twice in the spring of 1990 and 1991. Small mammals were trapped three times during each activity season (April?October) to obtain population estimates before and after spraying and in the spring preceding fall spraying or the fall following spring spraying. Population estimates immediately after spraying gave no evidence of direct mortality. By 1991, dicot vegetation on treated plots was suppressed and mean numbers of meadow voles (Microtus pennsylvanicus) were less than on control plots. Because meadow voles favor dicots over monocots in their diet, reduced availability of dicots may have been related to the smaller vole population estimates. Species diversity of small mammals was negatively correlated with size of vole populations, but was not different between treated and control plots. Brominal apparently induced opaque corneas in nine voles. The condition was found in two voles too small to have been conceived at the time of the last previous spray nearly 8 months earlier, suggesting exposure to residue alone.

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    B. J. Costa

    1998-06-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    CARVALHO Sílvia Magaly Sasso

    1999-01-01

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

  5. An Overview of Liquid Fluoride Salt Heat Transport Systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

  7. Fluorides in groundwater and its impact on health.

    Science.gov (United States)

    Shailaja, K; Johnson, Mary Esther Cynthia

    2007-04-01

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

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

    International Nuclear Information System (INIS)

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

  9. Improved fluoride volatility reprocessing for MOX fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  10. A Review on Adsorption of Fluoride from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Mirna Habuda-Stanić

    2014-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Zeynep Okte

    2012-02-01

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

  12. Accumulation of organochlorines and brominated flame retardants in estuarine and marine food chains: Field measurements and model calculations

    NARCIS (Netherlands)

    Veltman, K.; Hendriks, J.; Huijbregts, M.; Leonards, P.E.G.; Heuvel-Greve, van den M.J.; Vethaak, D.

    2005-01-01

    Food chain accumulation of organochlorines and brominated flame retardants in estuarine and marine environments is compared to model estimations and fresh water field data. The food chain consists of herbivores, detritivores and primary and secondary carnivores i.e. fish, fish-eating birds and marin

  13. Corrosion mechanism of 13Cr stainless steel in completion fluid of high temperature and high concentration bromine salt

    International Nuclear Information System (INIS)

    Highlights: • The corrosion behavior of 13Cr steel exposed to bromine salt completion fluid containing high concentration bromine ions was investigated. • There are passive circles around pits on the 13Cr steel surface after 7 d of exposure. • Macroscopic galvanic corrosion formed between the passive halo and the pit. • The mechanism of pitting corrosion on 13Cr stainless steel exposed to heavy bromine brine was established. - Abstract: A series of corrosion tests of 13Cr stainless steel were conducted in a simulated completion fluid environment of high temperature and high concentration bromine salt. Corrosion behavior of specimens and the component of corrosion products were investigated by means of scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The results indicate that 13Cr steel suffers from severe local corrosion and there is always a passive halo around every pit. The formation mechanism of the passive halo is established. OH− ligand generates and adsorbs in a certain scale because of abundant OH− on the surface around the pits. Passive film forms around each pit, which leads to the occurrence of passivation in a certain region. Finally, the dissimilarities in properties and morphologies of regions, namely the pit and its corresponding passive halo, can result in different corrosion sensitivities and may promote the formation of macroscopic galvanic pairs

  14. Corrosion mechanism of 13Cr stainless steel in completion fluid of high temperature and high concentration bromine salt

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yan [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083 (China); Xu, Lining, E-mail: xulining@ustb.edu.cn [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083 (China); Lu, Minxu [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083 (China); Meng, Yao [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhu, Jinyang; Zhang, Lei [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083 (China)

    2014-09-30

    Highlights: • The corrosion behavior of 13Cr steel exposed to bromine salt completion fluid containing high concentration bromine ions was investigated. • There are passive circles around pits on the 13Cr steel surface after 7 d of exposure. • Macroscopic galvanic corrosion formed between the passive halo and the pit. • The mechanism of pitting corrosion on 13Cr stainless steel exposed to heavy bromine brine was established. - Abstract: A series of corrosion tests of 13Cr stainless steel were conducted in a simulated completion fluid environment of high temperature and high concentration bromine salt. Corrosion behavior of specimens and the component of corrosion products were investigated by means of scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The results indicate that 13Cr steel suffers from severe local corrosion and there is always a passive halo around every pit. The formation mechanism of the passive halo is established. OH{sup −} ligand generates and adsorbs in a certain scale because of abundant OH{sup −} on the surface around the pits. Passive film forms around each pit, which leads to the occurrence of passivation in a certain region. Finally, the dissimilarities in properties and morphologies of regions, namely the pit and its corresponding passive halo, can result in different corrosion sensitivities and may promote the formation of macroscopic galvanic pairs.

  15. Exposure to brominated trihalomethanes in water during pregnancy and micronuclei frequency in maternal and cord blood lymphocytes

    DEFF Research Database (Denmark)

    Stayner, Leslie Thomas; Pedersen, Marie; Patelarou, Evridiki;

    2014-01-01

    BACKGROUND: Water disinfection by-products have been associated with an increased cancer risk. Micronuclei (MN) frequency in lymphocytes is a marker of genomic damage and can predict adult cancer risk. OBJECTIVE: We evaluated maternal exposure to drinking water brominated trihalomethanes (BTHM) i...

  16. Preparation of bromine-77 labelled monoclonal anti-hPLAP [human placental alkaline phosphatase] antibody using chloramine-T

    International Nuclear Information System (INIS)

    A tumor-associated monoclonal antibody, named 7E8 and raised against human placental alkaline phosphatase (hPLAP), is labelled with bromine-77 by means of chloramine-T. The paper describes optimum radiobromination conditions resulting in 34 % radiochemical yield of labelled antibody with more than 90 % immunoreactivity. (author)

  17. Prenatal Exposure to Organohalogens, Including Brominated Flame Retardants, Influences Motor, Cognitive, and Behavioral Performance at School Age

    NARCIS (Netherlands)

    Roze, Elise; Meijer, Lisethe; Bakker, Attie; Van Braeckel, Koenraad N. J. A.; Sauer, Pieter J. J.; Bos, Arend F.

    2009-01-01

    BACKGROUND: Organohalogen compounds (OHCs) are known to have neurotoxic effects on the developing brain. OBJECTIVE: We investigated the influence of prenatal exposure to OHCs, including brominated flame retardants, on motor, cognitive, and behavioral outcome in healthy children of school age. METHOD

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-10-25

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

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

    LENUS (Irish Health Repository)

    Mullen, J

    2012-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Carmalin Sophia Ayyappan

    2015-09-01

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

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

    International Nuclear Information System (INIS)

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

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

    NARCIS (Netherlands)

    Staden JJ van; Hoop MAGT van den; LAC

    1996-01-01

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

  4. The Karlsruhe 4π barium fluoride detector

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2010-01-01

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

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

    OpenAIRE

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

    2006-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

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

    OpenAIRE

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

    2010-01-01

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

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

    Indian Academy of Sciences (India)

    Barun kumar Datta; Chirantan Kar; Gopal Das

    2015-02-01

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

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

    OpenAIRE

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

    2012-01-01

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

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

    OpenAIRE

    Blagojević Duška; Stojšin Ivana

    2004-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.B.

    1979-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Sneha Panchal

    2014-03-01

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

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

    OpenAIRE

    ŞİRELİ, Meltem

    2004-01-01

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

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

    OpenAIRE

    Ene Indermitte; Astrid Saava; Enn Karro

    2014-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-01

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

  18. Development of multifunctional chitosan beads for fluoride removal

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Twetman, S

    2009-01-01

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

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

    Science.gov (United States)

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

    2011-05-01

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