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Sample records for silver uranium fluoride

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

    PubMed

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

    2009-02-01

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

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

    SciTech Connect

    Just, R.A.

    1988-01-01

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

  3. Fluid-bed fluoride volatility process recovers uranium from spent uranium alloy fuels

    NASA Technical Reports Server (NTRS)

    Barghusen, J. J.; Chilenskas, A. A.; Gunderson, G. E.; Holmes, J. T.; Jonke, A. A.; Kincinas, J. E.; Levitz, N. M.; Potts, G. L.; Ramaswami, D.; Stethers, H.; hide

    1967-01-01

    Fluid-bed fluoride volatility process recovers uranium from uranium fuels containing either zirconium or aluminum. The uranium is recovered as uranium hexafluoride. The process requires few operations in simple, compact equipment, and eliminates aqueous radioactive wastes.

  4. PROCESS FOR THE PRODUCTION OF AMMONIUM URANIUM FLUORIDE

    DOEpatents

    Ellis, A.S.; Mooney, R.B.

    1953-08-25

    This patent relates to the preparation of ammonium uranium fluoride. The process comprises adding a water soluble fluoride to an aqueous solution of a uranous compound containing an ammonium salt, and isolating the resulting precipitate. This patent relates to the manufacture of uranium tetnafluoride from ammonium uranium fluoride, NH/sub 4/UF/sub 5/. Uranium tetrafluoride is prepared by heating the ammonium uranium fluoride to a temperature at which dissociation occurs with liberation of ammonium fluoride. Preferably the process is carried out under reduced pressure, or in a current of an inert gas.

  5. PROCESS OF PREPARING A FLUORIDE OF TETRAVLENT URANIUM

    DOEpatents

    Wheelwright, E.J.

    1959-02-17

    A method is described for producing a fluoride salt pf tetravalent uranium suitable for bomb reduction to metallic uranium. An aqueous solution of uranyl nitrate is treated with acetic acid and a nitrite-suppressor and then contacted with metallic lead whereby uranium is reduced from the hexavalent to the tetravalent state and soluble lead acetate is formed. Sulfate ions are then added to the solution to precipitate and remove the lead values. Hydrofluoric acid and alkali metal ions are then added causing the formation of an alkali metal uranium double-fluoride in which the uranium is in the tetravalent state. After recovery, this precipitate is suitable for using in the limited production of metallic uranium.

  6. Preparation of thin film silver fluoride electrodes from constituent elements

    NASA Technical Reports Server (NTRS)

    Odonnell, P. M.

    1972-01-01

    The feasibility of preparing thin-film metal fluoride electrodes from the elemental constituents has been demonstrated. Silver fluoride cathodes were prepared by deposition of silver on a conducting graphite substrate followed by fluorination under controlled conditions using elemental fluorine. The resulting electrodes were of high purity, and the variables such as size, shape, and thickness were easily controlled.

  7. Magnetic separation of uranium from magnesium fluoride

    SciTech Connect

    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.

  8. FLUORIDE VOLATILITY PROCESS FOR THE RECOVERY OF URANIUM

    DOEpatents

    Katz, J.J.; Hyman, H.H.; Sheft, I.

    1958-04-15

    The separation and recovery of uraniunn from contaminants introduced by neutron irradiation by a halogenation and volatilization method are described. The irradiated uranium is dissolved in bromine trifluoride in the liquid phase. The uranium is converted to the BrF/sub 3/ soluble urmium hexafluoride compound whereas the fluorides of certain contaminating elements are insoluble in liquid BrF/sub 3/, and the reaction rate of the BrF/sub 3/ with certain other solid uranium contamirnnts is sufficiently slower than the reaction rate with uranium that substantial portions of these contaminating elements will remain as solids. These solids are then separated from the solution by a distillation, filtration, or centrifugation step. The uranium hexafluoride is then separated from the balance of the impurities and solvent by one or more distillations.

  9. A EPR Investigation of Atomic Silver and Divalent Silver in Irradiated Single Crystal of Potassium Fluoride Doped with Silver Fluoride

    NASA Astrophysics Data System (ADS)

    Yu, Cheng

    The electron paramagnetic resonance absorption spectra of a singly ionized diatomic fluoride molecule -ion F_2^-, atomic silver Ag^0 and divalent silver Ag ^{2+} contained in single crystals of potassium fluoride have been re-examined at X-band wavelengths. The F_2^- and Ag^0 centers are produced simultaneously by gamma-irradiation at liquid nitrogen temperature. The divalent silver Ag^{2+} centers are formed by subsequently warming the irradiated samples to room temperature for a few hours and then cooling to 77 K. All field strength positions of resonance absorption lines observed at low temperatures have been satisfactorily predicted by computer simulation. The high degree of resolution exhibited by the spectra is due in part to the large nuclear magnetic moment of fluorine and in part to the fact that spectral lines in KF are narrow compared to those of similar systems in other alkali halide crystals. For an atomic silver, the hexafluoride cluster is cubic. By contrast, the divalent silver center is tetragonally distorted along a crystal cube edge as a consequence of the Jahn-Teller effect. Unexpected splittings of the central lines in the resonance absorption spectrum of divalent silver are observed and interpreted as being due to second order perturbation effects.

  10. Carbide/fluoride/silver self-lubricating composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor)

    1988-01-01

    A self-lubricating, friction and wear reducing composite material for use over a wide temperature spectrum from cryogenic temperature to about 900.degree. C. in a chemically reactive environment comprising silver, barium fluoride/calcium fluoride eutectic, and metal bonded chromium carbide.

  11. Carbide-fluoride-silver self-lubricating composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor)

    1987-01-01

    A self-lubricating, friction and wear reducing composite material is described for use over a wide temperature spectrum from cryogenic temperature to about 900 C in a chemically reactive environment comprising silver, barium fluoride/calcium fluoride eutectic, and metal bonded chromium carbide.

  12. Uranium fluoride and metallic uranium as target materials for heavy-element experiments at SHIP

    NASA Astrophysics Data System (ADS)

    Kindler, Birgit; Ackermann, Dieter; Hartmann, Willi; Heßberger, Fritz Peter; Hofmann, Sigurd; Hübner, Annett; Lommel, Bettina; Mann, Rido; Steiner, Jutta

    2008-06-01

    In this contribution we describe the production and application of uranium targets for synthesis of heavy elements. The targets are prepared from uranium fluoride (UF 4) and from metallic uranium with thin carbon foils as backing. Targets of UF 4 were produced by thermal evaporation in a similar way as the frequently applied targets out of Bi, Bi 2O 3, Pb, PbS, SmF 3, and NdF 3, prepared mostly from isotopically enriched material [Birgit Kindler, et al., Nucl. Instr. and Meth. A 561 (2006) 107; Bettina Lommel, et al., Nucl. Instr. and Meth. A 561 (2006) 100]. In order to use more intensive beams and to avoid scattering of the reaction products in the target, metallic uranium is favorable. However, evaporation of metallic uranium is not feasible at a sustainable yield. Therefore, we established magnetron sputtering of metallic uranium. We describe production and properties of these targets. First irradiation tests show promising results.

  13. Formation of Fluorohydroxyapatite with Silver Diamine Fluoride.

    PubMed

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

    2017-09-01

    Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared-calcium phosphate (CaCl2·2H2O + K2HPO4 in buffer solution) and SDF (Ag[NH3]2F in buffer solution). After incubation at 37 (o)C for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with reduced

  14. Removal of fluoride and uranium by nanofiltration and reverse osmosis: a review.

    PubMed

    Shen, Junjie; Schäfer, Andrea

    2014-12-01

    Inorganic contamination in drinking water, especially fluoride and uranium, has been recognized as a worldwide problem imposing a serious threat to human health. Among several treatment technologies applied for fluoride and uranium removal, nanofiltration (NF) and reverse osmosis (RO) have been studied extensively and proven to offer satisfactory results with high selectivity. In this review, a comprehensive summary and critical analysis of previous NF and RO applications on fluoride and uranium removal is presented. Fluoride retention is generally governed by size exclusion and charge interaction, while uranium retention is strongly affected by the speciation of uranium and size exclusion usually plays a predominant role for all species. Adsorption on the membrane occurs as some uranium species interact with membrane functional groups. The influence of operating conditions (pressure, crossflow velocity), water quality (concentration, solution pH), solute–solute interactions, membrane characteristics and membrane fouling on fluoride and uranium retention is critically reviewed.

  15. Chemical analysis of uranium compounds. [For Fe, Ni, fluoride

    SciTech Connect

    Jarabek, R.J.

    1987-10-01

    Research and development studies relating to gaseous diffusion plants require expertise in the analysis of uranium and its compounds. Synthesis of these compounds along with subsequent use necessitates a means of identification in addition to X-ray diffraction patterns normally obtained. Analyses for fluoride, nickel, and iron have been developed to supplement the analysis for U/sup +4/ and U total previously developed. The fluoride is determined by pyrolysis, with subsequent acid-base titration. Nickel is analyzed by precipitation with dimethylglyoxime following complexation of the uranium with citric acid. Iron is analyzed iodometrically following an ammonium hydroxide-ammonium carbonate separation process from the uranium. High precision and accuracy can be obtained on these procedures using low-cost, wet chemical methods. Expensive computerized equipment is not needed. Uranium compounds analyzed include UF/sub 5/, UO/sub 2/F/sub 2/, U/sub 3/O/sub 8/, and U/sub 2/F/sub 9/.

  16. Silver Diamine Fluoride Treatment Considerations in Children's Caries Management.

    PubMed

    Crystal, Yasmi O; Niederman, Richard

    2016-11-15

    By arresting and preventing caries, silver diamine fluoride (SDF) offers an alternate care path for patients for whom traditional restorative treatment is not immediately available. Current data from controlled clinical trials encompassing more than 3,900 children indicate that biannual application of SDF reduces progression of current caries and risk of subsequent caries. The purpose of this paper was to highlight the best evidence from systematic reviews and clinical trials for clinicians to consider the benefits, risks, and limitations as they implement silver diamine fluoride therapy on young children.

  17. Nano Silver Fluoride for preventing caries.

    PubMed

    Burns, Jacky; Hollands, Kate

    2015-03-01

    Randomised controlled trial, double blind, in a community setting. School children with active caries in primary teeth and no pulpal exposure, fistula or decay in permanent teeth were chosen. Caries and unsupported enamel were left as found and cotton wool rolls were used for isolation. Two drops of NSF or one drop of water were applied to the tooth with a microbrush for two minutes, once in a 12-month period. At one week, five months and 12 months the presence of active caries, as classified using International Caries Detection and Assessment System (ICDAS II) criteria, was measured. If a blunt probe easily penetrated dentine with light force, active caries was recorded and taken to be a failure. One hundred and thirty primary teeth in 60 children with a mean age of 6.31 (± 0.60) were randomised. Sixty-three teeth were in the NSF group and 67 in the control group. After one week there were no losses, at the five-month follow up eight teeth were lost from the NSF group due to exfoliation or extraction and five from the control group. At twelve months a further five teeth were lost from the NSF group and 13 from the control group.At the one week follow up there was a 19% failure rate in the NSF group compared to 100% in the control group. At the five month recall this was 27.3% NSF compared to 72.6% water and at the final recall there was a 33.3% NSF failure rate and 65.3% control failure rate. The preventative fraction at this point was 50% and the NNT 3.12. All were statistically significant results (p= <0.05). The annual application of NSF solution was more effective in hardening and arresting dentine caries in primary teeth than the placebo. The effectiveness of NSF was found to be similar to silver diamine fluoride when applied once a year, but did not stain the dental tissue black and had no metallic taste. The application is simple, does not require a clinical setting and is inexpensive. NSF was demonstrated to be effective in arresting caries in children in

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

    PubMed

    Ariffin, Z; Ngo, H; McIntyre, J

    2006-12-01

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

  19. Silver diamine fluoride (SDF) may be better than fluoride varnish and no treatment in arresting and preventing cavitated carious lesions.

    PubMed

    Beltrán-Aguilar, Eugenio D

    2010-06-01

    Silver diamine fluoride: A caries "silver-fluoride bullet." Rosenblatt A, Stamford TCM, Niederman R. J Dent Res 2009;88(2):116-25. Eugenio D. Beltrán-Aguilar, DMD, MPH, MS, DrPH, Diplomate ABDPH PURPOSE/QUESTION: The authors conducted a systematic review of clinical studies on the effectiveness of silver diamine fluoride to arrest and prevent dental caries at the cavitated level. NIH Grant (DOI:10.1177/0022034508329406) Systematic review Level 2: Limited-quality patient-oriented evidence STRENGTH OF THE RECOMMENDATION GRADE: Grade B: Limited-quality patient-oriented evidence.

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

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

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

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

    PubMed

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

    2013-07-01

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

  2. Effect of laser irradiation on the fluoride uptake of silver diamine fluoride treated dentine.

    PubMed

    Mei, May L; Ito, Leticia; Zhang, C F; Lo, Edward C M; Chu, C H

    2015-04-01

    This study aimed to evaluate the fluoride uptake of dentine treated with a 38 % silver diamine fluoride (SDF) solution and laser irradiation at sub-ablative energy levels. Fifteen human dentine slices were prepared and divided into four samples each. Four types of laser were chosen: CO2 (10,600 nm), Er:YAG (2,940 nm), Nd:YAG (1,064 nm) and Diode (810 nm). First, the four samples from 12 of the dentine slices were treated with SDF, and then irradiated by one of the four types of laser at three different settings. One sample was untreated and acted as a control. The setting that rendered the highest fluoride uptake was selected. Second, the remaining dentine slices were treated with SDF and irradiated by the four lasers with the selected settings. Fluoride uptake was assessed using Energy Dispersive X-ray Spectrometry at the dentine surface and up to 20 μm below the surface. The selected settings were CO2 irradiation at 1.0 W for 1 s, Er:YAG irradiation at 0.5 W for 20 s, Nd:YAG irradiation at 2.0 W for 1 s and diode irradiation at 3.0 W for 3 s. The fluoride content (weight %) at the dentine surface following CO2, Er:YAG, Nd:YAG and diode irradiation was 6.91 ± 3.15, 4.09 ± 1.19, 3.35 ± 2.29 and 1.73 ± 1.04, respectively. CO2 and Er:YAG irradiation resulted in higher fluoride uptake than Nd:YAG and diode irradiation at all levels (p < 0.05). CO2 laser and Er:YAG laser irradiation rendered higher fluoride uptake in the SDF-treated dentine than Nd:YAG laser and diode laser irradiation.

  3. Clinical Use of Silver Diamine Fluoride in Dental Treatment.

    PubMed

    Mei, May L; Lo, Edward Chin-Man; Chu, Chun-Hung

    2016-02-01

    The use of a topical fluoride solution, namely silver diamine fluoride (SDF), in dental treatment has been drawing increasing attention. SDF has been used in some countries in Asia, including Japan and China, as a caries-arresting and anti-hypersensitivity agent. It was recently cleared by the Food and Drug Administration in the United States as a fluoride to manage hypersensitive teeth. Topical application of SDF is a noninvasive procedure that is quick and simple to use. Promising results of laboratory studies and clinical trials have suggested that SDF is more effective than other fluoride agents to halt the caries process. A review concluded that SDF is a safe, effective, efficient, and equitable caries control agent that has a potentially broad application in dentistry and may meet the criteria of both the WHO Millennium Development Goals and the US Institute of Medicine's criteria for 21st century medical care. This article provides an overview of the clinical use of SDF in dental treatment.

  4. The inhibitory effects of silver diamine fluorides on cysteine cathepsins.

    PubMed

    Mei, May L; Ito, L; Cao, Y; Li, Q L; Chu, C H; Lo, Edward C M

    2014-03-01

    The expression of cysteine cathepsins in human carious dentine suggests that this enzyme contributes to the collagen degradation in caries progress. This study investigated whether silver diamine fluoride (SDF) inhibited the activity of cysteine cathepsins. Three commercial SDF solutions with concentrations at 38%, 30% and 12% were studied. Two fluoride solutions with the same fluoride ion (F(-)) concentrations as the 38% and 12% SDF solutions, and 2 silver solutions with the same silver ion (Ag(+)) concentrations as the 38% and 12% SDF solutions were prepared. Five samples of each experimental solution were used to study their inhibitory effect on two cathepsins (B and K) using cathepsin assay kits. Positive control contained assay buffer and cathepsins dilution was used to calculate the percentage inhibition (difference between the mean readings of the test solution and control solution divided by that of the control group). The percentage inhibition of 38%, 30% and 12% SDF on cathepsin B were 92.0%, 91.5% and 90.3%, respectively (p<0.001); on cathepsin K were 80.6%, 78.5% and 77.9%, respectively (p<0.001). Ag(+) exhibited the inhibitory effect against both cathepsin B and K with or without the presence of F(-) (p<0.01). The solutions containing Ag(+) have significantly higher inhibitory effect than the solutions containing F(-) only (p<0.01). According to this study, SDF solution at all 3 tested concentrations significantly inhibited the activity of cathepsin B and K. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  5. Silver Diamine Fluoride in Pediatric Dentistry Training Programs: Survey of Graduate Program Directors.

    PubMed

    Nelson, Travis; Scott, Joanna M; Crystal, Yasmi O; Berg, Joel H; Milgrom, Peter

    2016-01-01

    The purpose of this study was to investigate practice, teaching, and perceived barriers to the use of silver diamine fluoride and other caries control agents in U.S. pediatric dentistry residency programs. A 14-question survey regarding use and teaching of caries control agents was sent via email to residency program directors in 2015. Survey participants responded, using a web-based survey tool, by completing a paper and pencil survey instrument, or by interview. Surveys were completed by 74 directors or associate directors (87 percent adjusted response rate). More than a quarter (25.7 percent) reported use of silver diamine fluoride, with 68.9 percent expecting to increase use. The use of silver diamine fluoride was not associated with region or program type. Programs reported commonly used caries control agents of fluoride varnish (100 percent), acidulated phosphate fluoride foam (48.6 percent), silver nitrate (9.5 percent), and povidone iodine (1.3 percent). Most felt silver diamine fluoride should be used only with high-risk patients (89.2 percent), and the majority agreed it could be used in primary and permanent teeth. The most frequently reported barrier to use of silver diamine fluoride was parental acceptance (91.8 percent). Silver diamine fluoride is being rapidly adopted in graduate pediatric dentistry training programs, with the majority expecting to incorporate it into their teaching clinics and curricula.

  6. Short term serum pharmacokinetics of diammine silver fluoride after oral application.

    PubMed

    Vasquez, Elsa; Zegarra, Graciela; Chirinos, Edgar; Castillo, Jorge L; Taves, Donald R; Watson, Gene E; Dills, Russell; Mancl, Lloyd L; Milgrom, Peter

    2012-12-31

    There is growing interest in the use of diammine silver fluoride (DSF) as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized. This preliminary study determined the applied doses (3 teeth treated), maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL). Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively. Fluoride exposure was below the U.S. Environmental Protection Agency (EPA) oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults. NCT01664871.

  7. Silver copper fluoride: A novel perovskite cathode for lithium batteries

    NASA Astrophysics Data System (ADS)

    Tong, Wei; Amatucci, Glenn G.

    2017-09-01

    An electrochemically active nanostructured silver copper fluoride (SCF) perovskite, AgCuF3, was synthesized via a mechanochemical reaction between AgF and CuF2 precursors. Phase composition and electrochemical properties of the SCF perovskites produced under various synthetic parameters were studied. The optimum SCF perovskite sample exhibited an appreciable electrochemical performance through the use of conductive carbon matrix in a primary lithium half cell. A high specific capacity of 270 mAh g-1 was achieved at a cutoff voltage of 2 V with 190 mAh g-1 above 3 V, leading to a total volumetric energy density of 3666 Wh L-1 at >3 V and 4848 Wh L-1 at >2 V.

  8. UCSF Protocol for Caries Arrest Using Silver Diamine Fluoride: Rationale, Indications, and Consent

    PubMed Central

    Horst, Jeremy A; Ellenikiotis, Hellene; Milgrom, Peter M

    2016-01-01

    The Food and Drug Administration recently cleared silver diamine fluoride for reducing tooth sensitivity. Clinical trials document arrest and prevention of dental caries by silver diamine fluoride; this off-label use is now permissible and appropriate under U.S. law. A CDT code was approved for caries arresting medicaments for 2016 to facilitate documentation and billing. We present a systematic review, clinical indications, clinical protocol, and consent procedure to guide application for caries arrest treatment. PMID:26897901

  9. UCSF Protocol for Caries Arrest Using Silver Diamine Fluoride: Rationale, Indications and Consent.

    PubMed

    Horst, Jeremy A; Ellenikiotis, Hellene; Milgrom, Peter L

    2016-01-01

    The Food and Drug Administration recently cleared silver diamine fluoride for reducing tooth sensitivity. Clinical trials document arrest and prevention of dental caries by silver diamine fluoride. This off-label use is now permissible and appropriate under U.S. law. A CDT code was approved for caries arresting medicaments for 2016 to facilitate documentation and billing. We present a systematic review, clinical indications, clinical protocol and consent procedure to guide application for caries arrest treatment.

  10. The short-term effects of diammine silver fluoride on tooth sensitivity: a randomized controlled trial.

    PubMed

    Castillo, J L; Rivera, S; Aparicio, T; Lazo, R; Aw, T-C; Mancl, L L; Milgrom, P

    2011-02-01

    Tooth sensitivity is a common clinical problem. This multi-center randomized clinical trial assessed the effectiveness and safety of topical diammine silver fluoride. From two sites (Lima and Cusco, Peru), 126 adults with at least one tooth sensitive to compressed air were randomly assigned to either the experimental treatment or sterile water, and pain was assessed by means of a 100-mm visual analogue scale at 24 hours and 7 days. The diammine silver fluoride reduced pain at 7 days at both sites. At the Lima site, the average change in pain scores between baseline and day 7 for the silver fluoride group was -35.8 (SD = 27.7) mm vs. 0.4 (SD = 16.2) mm for the control group (P < 0.001). In Cusco, the average change in pain scores for the silver fluoride group was -23.4 (SD = 21.0) mm and -5.5 (18.1) mm for the control group (P = 0.002). No tissue ulceration, white changes, or argyria was observed. A small number of participants in the silver fluoride group experienced a mild but transient increase in erythema in the gingiva near the tooth. No changes were observed in the Gingival Index. We concluded that diammine silver fluoride is a clinically effective and safe tooth desensitizer.

  11. PRECIPITATION OF URANIUM PEROXIDE OF LOW FLUORIDE CONTENT FROM SOLUTIONS CONTAINING FLUORIDES

    DOEpatents

    King, E.J.; Clark, H.M.

    1958-08-12

    S>A method is described for the preparation of fluoride free uraniunn peroxide precipitates, even though the solution from which the precipitation is made is contaminated with fluorides. This is accomplished by add ing aluminum ions to the solution, where they complex any fluoride present and prevent its precipitation with the uramum peroxide.

  12. Short term serum pharmacokinetics of diammine silver fluoride after oral application

    PubMed Central

    2012-01-01

    Background There is growing interest in the use of diammine silver fluoride (DSF) as a topical agent to treat dentin hypersensitivity and dental caries as gauged by increasing published research from many parts of the world. While DSF has been available in various formulations for many years, most of its pharmacokinetic aspects within the therapeutic concentration range have never been fully characterized. Methods This preliminary study determined the applied doses (3 teeth treated), maximum serum concentrations, and time to maximum serum concentration for fluoride and silver in 6 adults over 4 h. Fluoride was determined using the indirect diffusion method with a fluoride selective electrode, and silver was determined using inductively coupled plasma-mass spectrometry. The mean amount of DSF solution applied to the 3 teeth was 7.57 mg (6.04 μL). Results Over the 4 hour observation period, the mean maximum serum concentrations were 1.86 μmol/L for fluoride and 206 nmol/L for silver. These maximums were reached 3.0 h and 2.5 h for fluoride and silver, respectively. Conclusions Fluoride exposure was below the U.S. Environmental Protection Agency (EPA) oral reference dose. Silver exposure exceeded the EPA oral reference dose for cumulative daily exposure over a lifetime, but for occasional use was well below concentrations associated with toxicity. This preliminary study suggests that serum concentrations of fluoride and silver after topical application of DSF should pose little toxicity risk when used in adults. Clinical trials registration NCT01664871. PMID:23272643

  13. Abnormally high fluoride levels in commercial preparations of 40 per cent silver fluoride solution: contraindications for use in children.

    PubMed

    Gotjamanos, T; Orton, V

    1998-12-01

    Although a 40 per cent solution of silver fluoride would be expected to contain 6 per cent fluoride (60,000 ppm), F-levels of 100,000 ppm and 120,000 ppm were found in 14 commercial samples analysed at The University of Western Australia in 1993 and 1994. To determine whether F-levels in 40 per cent AgF preparations have remained high, the present investigation was aimed at analysing different batches of commercial preparations obtained more recently. Fluoride ion analysis was carried out on 24 AgF samples using the Ion-Selective Electrode technique. Independent analyses of the same samples were carried out by a private chemical testing laboratory (Genalysis). Ten samples supplied by Agson Chemical Export were found to contain between 75,000 and 100,000 ppm F-: Genalysis reported 80,000 to 120,000 ppm. Fourteen samples supplied by Southern Dental Industries were found to contain between 70,000 and 120,000 ppm F-; Genalysis reported 88,000 to 108,000 ppm F-. These results confirm significantly higher than expected F-levels (ANOVA p < 0.05) in commercial preparations of 40 per cent AgF. The solutions tested were found to contain a mixture of ammonium fluoride, sodium or potassium fluoride, and silver fluoride. The additional presence of silver difluoride and hydrofluoric acid resulting from the manufacturing process has been suggested as an explanation for the much higher than expected levels of fluoride ion. In view of possible toxicity of 40 per cent AgF in young children, it is concluded that such a highly concentrated solution should not be used clinically; instead, lower strength AgF solutions should be investigated for their efficacy in caries treatment.

  14. Efficacy of silver diamine fluoride for Arresting Caries Treatment.

    PubMed

    Yee, R; Holmgren, C; Mulder, J; Lama, D; Walker, D; van Palenstein Helderman, W

    2009-07-01

    Arresting Caries Treatment (ACT) has been proposed to manage untreated dental caries in children. This prospective randomized clinical trial investigated the caries-arresting effectiveness of a single spot application of: (1) 38% silver diamine fluoride (SDF) with tannic acid as a reducing agent; (2) 38% SDF alone; (3) 12% SDF alone; and (4) no SDF application in primary teeth of 976 Nepalese schoolchildren. The a priori null hypothesis was that the different treatments have no effect in arresting active cavitated caries. Only the single application of 38% SDF with or without tannic acid was effective in arresting caries after 6 months (4.5 and 4.2 mean number of arrested surfaces; p < 0.001), after 1 year (4.1 and 3.4; p < 0.001), and after 2 years (2.2 and 2.1; p < 0.01). Tannic acid conferred no additional benefit. ACT with 38% SDF provides an alternative when restorative treatment for primary teeth is not an option.

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

    PubMed

    Chu, C H; Lo, E C M; Lin, H C

    2002-11-01

    Untreated dental caries in Chinese pre-school children is common. This prospective controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries. Three hundred seventy-five children, aged 3-5 years, with carious upper anterior teeth were divided into five groups. Children in the first and second groups received annual applications of silver diamine fluoride solution (44,800 ppm F). Sodium fluoride varnish (22,600 ppm F) was applied every three months to the lesions of children in the third and fourth groups. For children in the first and third groups, soft carious tissues were removed prior to fluoride application. The fifth group was the control. Three hundred eight children were followed for 30 months. The respective mean numbers of arrested carious tooth surfaces in the five groups were 2.5, 2.8, 1.5, 1.5, and 1.3 (p < 0.001). Silver diamine fluoride was found to be effective in arresting dentin caries in primary anterior teeth in pre-school children.

  16. Effectiveness of silver diamine fluoride in caries prevention and arrest: a systematic literature review.

    PubMed

    Contreras, Violeta; Toro, Milagros J; Elías-Boneta, Augusto R; Encarnación-Burgos, Angeliz

    2017-01-01

    This study aimed to evaluate the scientific evidence regarding the effectiveness of silver diamine fluoride (SDF) in preventing and arresting caries in the primary dentition and permanent first molars. A systematic review (SR) was performed by 2 independent reviewers using 3 electronic databases (PubMed, ScienceDirect, and Scopus). The database search employed the following key words: "topical fluorides" AND "children" AND "clinical trials"; "topical fluorides" OR "silver diamine fluoride" AND "randomized controlled trial"; "silver diamine fluoride" AND "children" OR "primary dentition" AND "tooth decay"; "silver diamine fluoride" OR "sodium fluoride varnish" AND "early childhood caries"; and "silver diamine fluoride" AND "children". Inclusion criteria were articles published in English, from 2005 to January 2016, on clinical studies using SDF as a treatment intervention to evaluate caries arrest in children with primary dentition and/or permanent first molars. Database searches provided 821 eligible publications, of which 33 met the inclusion criteria. After the abstracts were prescreened, 25 articles were dismissed based on exclusion criteria. The remaining 8 full-text articles were assessed for eligibility. Of these, 7 publications were included in the SR. These included 1 study assessing the effectiveness of SDF at different concentrations; 3 studies comparing SDF with other interventions; 2 investigations comparing SDF at different application frequencies and with other interventions; and 1 study comparing semiannual SDF applications versus a control group. The literature indicates that SDF is a preventive treatment for dental caries in community settings. At concentrations of 30% and 38%, SDF shows potential as an alternative treatment for caries arrest in the primary dentition and permanent first molars. To establish guidelines, more studies are needed to fully assess the effectiveness of SDF and to determine the appropriate application frequency.

  17. Prevention of secondary caries by silver diamine fluoride.

    PubMed

    Mei, May Lei; Zhao, Irene Shuping; Ito, Leticia; Lo, Edward Chin-Man; Chu, Chun-Hung

    2016-04-01

    This study aimed to investigate the use of 38% silver diamine fluoride (SDF) as a treatment for preventing secondary caries in glass ionomer cement (GIC) and composite resin (CR) restorations. Six extracted human sound premolars were collected. Four cavities (4 × 2 × 2 mm(3) ) were prepared on each premolar and then allocated to the following restoration groups: group 1, SDF conditioning and GIC restoration; group 2, GIC restoration; group 3, SDF conditioning and CR restoration; and group 4, CR restoration. After thermal cycling and sterilisation, the teeth were soaked in a 5% sucrose solution containing Streptococcus mutans and Lactobacillus acidophilus for 28 days. Micro-computed tomography was used to study demineralisation. The outer lesion depth (OLD) and wall lesion depth (WLD) of the tooth-restoration interface were measured. The OLD and WLD were directly related to the extent of secondary caries. Two-way analysis of variance was used to analyse the effects of SDF conditioning and restorative materials on OLD. The mean ± standard deviation OLD values were 156 ± 45 μm, 235 ± 33 μm, 153 ± 20 μm and 232 ± 24 μm for groups 1-4, respectively. The OLD was less in restorations with SDF conditioning (P < 0.001) than in those without SDF conditioning. No interaction effect on OLD was found between the restorative materials and SDF conditioning (P = 0.062). The WLD was detected only in groups 3 and 4. Conditioning with 38% SDF can increase resistance of GIC and CR restorations to secondary caries. © 2015 FDI World Dental Federation.

  18. Effect of fluoridated varnish and silver diamine fluoride solution on enamel demineralization: pH-cycling study.

    PubMed

    Delbem, Alberto Carlos Botazzo; Bergamaschi, Maurício; Sassaki, Kikue Takebayashi; Cunha, Robson Frederico

    2006-04-01

    In the present investigation, the anticariogenic effect of fluoride released by two products commonly applied in infants was evaluated. Bovine sound enamel blocks were randomly allocated to each one of the treatment groups: control (C), varnish (V) and diamine silver fluoride solution (D). The blocks were submitted to pH cycles in an oven at 37 degrees C. Next, surface and cross-sectional microhardness were assessed to calculate the percentage loss of surface microhardness (%SML) and the mineral loss (deltaZ). The fluoride present in enamel was also determined. F/Px10(-3) (ANOVA, p<0.05) in the 1st layer of enamel before pH-cycling were (C, V and D): 1.61; 21.59 and 3.98. The %SMH (Kruskal-Wallis, p<0.05) were: -64.0, -45.2 and -53.1. %deltaZ values (ANOVA, p<0.05) were: -18.7 feminine, -7.7 and -17.3 feminine. The data suggested that the fluoride released by varnish showed greater interaction with sound enamel and provided less mineral loss when compared with silver diamine solution.

  19. EFFECT OF FLUORIDATED VARNISH AND SILVER DIAMINE FLUORIDE SOLUTION ON ENAMEL DEMINERALIZATION: pH-CYCLING STUDY

    PubMed Central

    Delbem, Alberto Carlos Botazzo; Bergamaschi, Maurício; Sassaki, Kikue Takebayashi; Cunha, Robson Frederico

    2006-01-01

    Objective: In the present investigation, the anticariogenic effect of fluoride released by two products commonly applied in infants was evaluated. Methods: Bovine sound enamel blocks were randomly allocated to each one of the treatment groups: control (C), varnish (V) and diamine silver fluoride solution (D). The blocks were submitted to pH cycles in an oven at 37°C. Next, surface and cross-sectional microhardness were assessed to calculate the percentage loss of surface microhardness (%SML) and the mineral loss (∆Z). The fluoride present in enamel was also determined. Results: F/Px10-3(ANOVA, p<0.05) in the 1stlayer of enamel before pH-cycling were (C, V and D): 1.61a; 21.59band 3.98c. The %SMH (Kruskal-Wallis, p<0.05) were: - 64.0a, -45.2band -53.1c. %∆Z values (ANOVA, p<0.05) were: -18.7a, -7.7band -17.3a. Conclusion: The data suggested that the fluoride released by varnish showed greater interaction with sound enamel and provided less mineral loss when compared with silver diamine solution. PMID:19089037

  20. Parental perceptions and acceptance of silver diamine fluoride staining.

    PubMed

    Crystal, Yasmi O; Janal, Malvin N; Hamilton, Dylan S; Niederman, Richard

    2017-07-01

    The caries arrest that can be achieved by using silver diamine fluoride (SDF) offers a minimally invasive and inexpensive alternative to traditional restorative caries treatment. The authors evaluated how the dentinal staining that is associated with SDF influences the acceptance of this treatment among parents of young children in the New York City metropolitan area. The authors invited the parents of children who had experienced dental caries and who had appointments at the New York University Pediatric Dentistry Clinic and at several private clinics in New Jersey to participate in a Web-based survey designed to assess parents' demographics, perceptions of photographs of SDF-treated carious teeth, and acceptability of treatment in different behavior management scenarios. Ninety-eight mothers and 22 fathers from diverse backgrounds participated. Most parents (67.5%) judged SDF staining on the posterior teeth to be esthetically tolerable, but only 29.7% of parents made this same judgment about anterior teeth (P < .001). In the absence of their child having behavioral barriers to conventional restorations, 53.6% of parents reported that they were likely to choose SDF to treat their child's posterior teeth, but only 26.9% of parents were likely to choose SDF to treat their child's anterior teeth. As the number of children's behavioral barriers increased, so did the parents' level of acceptance. In extreme cases, in which parents had to decide whether their children should undergo general anesthesia during treatment, parents' acceptance rate of SDF as a treatment method increased to 68.5% on posterior teeth and to 60.3% on anterior teeth. Parents' acceptance of the treatment also varied according to their socioeconomic status. Staining on posterior teeth was more acceptable than staining on anterior teeth. Although staining on anterior teeth was undesirable, most parents preferred this option to advanced behavioral techniques such as sedation or general anesthesia

  1. 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.

    PubMed

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

    2013-01-01

    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. 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. 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. In vivo application of SDF on enamel significantly decreases S. mutans counts as compared to fluoride varnish and APF gel.

  2. Reactions of aluminum with uranium fluorides and oxyfluorides

    SciTech Connect

    Leitnaker, J.M.; Nichols, R.W.; Lankford, B.S.

    1991-12-31

    Every 30 to 40 million operating hours a destructive reaction is observed in one of the {approximately}4000 large compressors that move UF{sub 6} through the gaseous diffusion plants. Despite its infrequency, such a reaction can be costly in terms of equipment and time. Laboratory experiments reveal that the presence of moderate pressures of UF{sub 6} actually cools heated aluminum, although thermodynamic calculations indicate the potential for a 3000-4000{degrees}C temperature rise. Within a narrow and rather low (<100 torr; 1 torr = 133.322 Pa) pressure range, however, the aluminum is seen to react with sufficient heat release to soften an alumina boat. Three things must occur in order for aluminum to react vigorously with either UF{sub 6} or UO{sub 2}F{sub 2}. 1. An initiating source of heat must be provided. In the compressors, this source can be friction, permitted by disruption of the balance of the large rotating part or by creep of the aluminum during a high-temperature treatment. In the absence of this heat source, compressors have operated for 40 years in UF{sub 6} without significant reaction. 2. The film protecting the aluminum must be breached. Melting (of UF{sub 5} at 620 K or aluminum at 930 K) can cause such a breach in laboratory experiments. In contrast, holding Al samples in UF{sub 6} at 870 K for several hours produces only moderate reaction. Rubbing in the cascade can undoubtedly breach the protective film. 3. Reaction products must not build up and smother the reaction. While uranium products tend to dissolve or dissipate in molten aluminum, AIF{sub 3} shows a remarkable tendency to surround and hence protect even molten aluminum. Hence the initial temperature rise must be rapid and sufficient to move reactants into a temperature region in which products are removed from the reaction site.

  3. Randomized clinical trial on arresting dental root caries through silver diamine fluoride applications in community-dwelling elders.

    PubMed

    2016-10-07

    The immediate application of potassium iodide to dental root caries treated with silver diamine fluoride improved the colour of the lesion from black to bright yellow, but this colour change was only short lived.

  4. National uranium resource evaluation: Silver City Quadrangle, New Mexico and Arizona

    SciTech Connect

    O'Neill, A J; Thiede, D S

    1982-05-01

    Reconnaissance and detailed geologic, geochemical, and radiometric studies were conducted throughout the Silver City Quadrangle, New Mexico and Arizona, to identify environments and delineate areas favorable for the occurrence of uranium deposits using National Uranium Resource Evaluation criteria. Surface and limited subsurface studies were augmented by aerial radiometric and hydrogeochemical and stream-sediment reconnaissance surveys. Results of the investigations indicate several areas favorable for magmatic-hydrothermal uranium deposits. They include Precambrian granitic, gneissic, and diabasic rocks; the Cretaceous Beartooth Quartzite where it overlies Precambrian granite; certain Laramide to mid-Tertiary monzonitic rocks; and Tertiary volcanic rocks adjacent to a quartz monzonitic stock. Studies also indicate environments favorable for allogenic deposits in the Tyrone laccolith and for uranium deposits in upper Cenozoic volcaniclastic lacustrine rocks. Formations judged unfavorable for magmatic-hydrothermal uranium deposits include large areas of Precambrian granitic and metamorphic rocks, almost all Laramide and mid-Tertiary intrusive rocks, and intruded Paleozoic and Cretaceous carbonate rocks. Precambrian metamorphic rocks are also considered unfavorable for contact metasomatic as well as for unconformity-related and vein-type uranium deposits. The entire Paleozoic and Cretaceous sedimentary section is considered unfavorable for sandstone and marine-black-shale uranium deposits. Moreover, mid-Tertiary rocks were judged unfavorable for volcanogenic uranium deposits, and upper Cenozoic basin-fill and surficial deposits are unfavorable for sandstone-type deposits and for uranium deposits associated with volcaniclastic lacustrine environments.

  5. Silver Plume Granite; possible source of uranium in sandstone uranium deposits, Tallahassee Creek and High Park areas, Fremont and Teller counties, Colorado

    USGS Publications Warehouse

    Hills, F.A.; Dickinson, K.A.

    1982-01-01

    Anomalously high concentrations of thorium and of the light rare earth elements lanthanum and cerium suggest that the actinides and light lanthanides were enriched to an abnormal degree by the magmatic processes that formed the Proterozoic Y Silver Plume Granite in areas adjoining Tallahassee Creek and High Park. However, no such enrichment is found in the Proterozoic X Boulder Creek Granodiorite. Although uranium presently does not appear to be significantly enriched in sampled outcrops of Silver Plume Granite, a large part of the original uranium content of Silver Plume may have been removed by oxidizing ground waters, leaving behind mainly the uranium bound in resistate minerals such as zircon and monazite. Lead isotopic compositions of acid leachate from barren shale and sandstone associated with the Hansen uranium deposit (Tallahassee Creek area) indicate that (1) the predominant source of acid-soluble lead is 1410 m.y: old (Silver Plume age); (2) the source of the lead is characterized by Th/U around 1 (this ratio in the source may apply to soluble minerals only and may exclude thorium and uranium in resistate minerals), and the mean uranium content of this source may be as high as 30 ppm; and (3) at the time of sediment deposition, a paleohydrologic system existed that was capable of transporting Silver Plume lead and, therefore, Silver Plume uranium to the Hansen deposit. Although a significant contribution of uranium from Tertiary volcanic rocks cannot be ruled out and is even probable (Dickinson and Hills, 1982), it appears probable that some of the uranium in deposits of the Tallahassee Creek area was derived from Silver Plume Granite.

  6. The inhibitory effects of silver diamine fluoride at different concentrations on matrix metalloproteinases.

    PubMed

    Mei, May L; Li, Q L; Chu, C H; Yiu, Cynthia K Y; Lo, Edward C M

    2012-08-01

    To study the inhibitory effect of various commercially available concentrations of silver diamine fluoride (SDF) solutions on matrix metalloproteinases (MMPs). Three SDF solutions with concentrations at 38%, 30% and 12% were studied. Two sodium fluoride (NaF) solutions at 10% and 3% were prepared, and they had the same fluoride ion concentrations as 38% and 12% SDF, respectively. Two silver nitrate (AgNO(3)) solutions at 42% and 13% were also prepared, and they had the same silver ion concentrations as 38% and 12% SDF, respectively. Ten samples of each experimental solution were used to study their inhibitory effect on three MMPs, which were MMP-2 (gelatinase A), MMP-8 (neutrophil collagenase) and MMP-9 (gelatinase B) using MMP assay kits. Positive control containing assay buffer at pH 9 and MMPs dilution was used to calculate the percentage inhibition. The percentage inhibition of 38%, 30% and 12% SDF on MMP-2 were 79%, 60% and 17%, respectively (p<0.001); on MMP-8 were 94%, 85% and 77%, respectively (p<0.001); on MMP-9 were 82%, 65% and 60%, respectively (p<0.001). The percentage inhibition on MMP-2, MMP-8 and MMP-9 by 38% SDF was significantly higher than the corresponding percentage inhibition by 10% NaF and 42% AgNO(3). Greater inhibitory effect on MMPs was found with higher concentration of SDF solution. SDF had more inhibition on MMPs than solutions of NaF and AgNO(3) containing equivalent concentration of fluoride and silver ions, respectively. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Limited Evidence Links Silver Diamine Fluoride and Caries Arrest in Children.

    PubMed

    Gold, Jaana

    2017-09-01

    Clinical trials of silver diamine fluoride in arresting caries among children: A systematic review. Gao SS, Zhao IS, Hiraishi N, Duangthi D, Mei ML, Lo ECM, Chu CH. JDR-CTR 2016;1:201-10. Academic research funding from the General Research Fund of the Research Grants Council of Hong Kong TYPE OF STUDY/DESIGN: Systematic review and meta-analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Method of making carbide/fluoride/silver composites

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor); Dellacorte, Christopher (Inventor)

    1991-01-01

    A composition containing 30 to 70 percent chromium carbide, 5 to 20 percent soft noble metal, 5 to 20 percent metal fluorides, and 20 to 60 percent metal binder is used in a powdered metallurgy process for the production of self-lubricating components, such as bearings. The use of the material allows the self-lubricating bearing to maintain its low friction properties over an extended range of operating temperatures.

  9. Uranium resources in the Silver Reef (Harrisburg) district, Washington County, Utah

    USGS Publications Warehouse

    Stugard, Frederick

    1951-01-01

    The Silver Reef district is near Leeds, about 16 miles north of St. George, Utah. The major structural feature of the district is the Virgin anticline, a fold extending southwestward toward St. George. The anticline has been breached by erosion, and sandstone hogbacks or 'reefs' are carved from the Shinarump conglomerate mud sandstone members of the Chinle formation, both of Triassic age. Thirteen occurrences of uranium-vanadium minerals, all within the Tecumseh sandstone, which is the upper part of the Silver Reef sandstone member of the Chinle formation, have been examined over an area about 1.75 miles wide and 3 miles long. Two shipments of uranium-vanadium ore have been produced from the Chloride Chief and Silver Point claims. Samples from the deposits contain as much as 0.94 percent U3O8. The ore contains several times as much vanadium oxide as uranium, some copper, and traces of silver. It occurs in thinly bedded cross-bedded shales and sandstones within the fluviatile Tecumseh sandstone member of the Chinle formation. The ore beds are lenticular and are localized 2 near the base, center, and top of this sandstone member. The uranium-vanadium ore contains several yellow and green minerals not yet identified; the occurrences are similar to, but not associated with, the cerargyrite ore that made the district famous from 1879 to 1909.

  10. Anti-microbial efficiency of silver diamine fluoride as an endodontic medicament - An ex vivo study.

    PubMed

    Mathew, Vinod B; Madhusudhana, Koppolu; Sivakumar, Nuvulla; Venugopal, Thangala; Reddy, Redderu K

    2012-07-01

    Antisepsis achieved through appropriate use of irrigants is essential for endodontic success. Identification of newer anti-bacterial agents gives alternatives to clean the canal as eradication of the infection prior to obturation does affect prognosis. Comparison of the anti-bacterial action of 3.8% silver diamine fluoride and 2% chlorhexidine gluconate against Enterococcus faecalis in root canals. Forty-four single-rooted teeth were decoronated, and the root section was enlarged with peeso-reamer (No: 3) to standardize length and diameter. The samples were then autoclaved and divided into two study groups and two control groups. Enterococcus faecalis ATCC 29212 was inoculated into all test samples for 72 hours. The samples were enlarged with peeso-reamer (No: 5) after placement of respective medicament for 24 hours. Shavings were collected and inoculated on Brain Heart Infusion agar for 24 hrs to measure the colony forming units. Both 3.8% silver diamine fluoride and 2% chlorhexidine showed a superior capacity to sterilize the root canals than control groups. The use of silver diamine fluoride as an endodontic irrigant is feasible as it can effectively remove the microbes present in the canal and circumpulpal dentin.

  11. Fluoride

    MedlinePlus

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

  12. Effectiveness of silver diamine fluoride in caries prevention and arrest: a systematic literature review

    PubMed Central

    Contreras, Violeta; Toro, Milagros J.; Elías-Boneta, Augusto R.; Encarnación-Burgos, Angeliz

    2017-01-01

    This study aimed to evaluate the scientific evidence regarding the effectiveness of silver diamine fluoride (SDF) in preventing and arresting caries in the primary dentition and permanent first molars. A systematic review (SR) was performed by 2 independent reviewers using 3 electronic databases (PubMed, ScienceDirect, and Scopus). The database search employed the following key words: “topical fluorides” AND “children” AND “clinical trials”; “topical fluorides” OR “silver diamine fluoride” AND “randomized controlled trial”; “silver diamine fluoride” AND “children” OR “primary dentition” AND “tooth decay”; “silver diamine fluoride” OR “sodium fluoride varnish” AND “early childhood caries”; and “silver diamine fluoride” AND “children”. Inclusion criteria were articles published in English, from 2005 to January 2016, on clinical studies using SDF as a treatment intervention to evaluate caries arrest in children with primary dentition and/or permanent first molars. Database searches provided 821 eligible publications, of which 33 met the inclusion criteria. After the abstracts were prescreened, 25 articles were dismissed based on exclusion criteria. The remaining 8 full-text articles were assessed for eligibility. Of these, 7 publications were included in the SR. These included 1 study assessing the effectiveness of SDF at different concentrations; 3 studies comparing SDF with other interventions; 2 investigations comparing SDF at different application frequencies and with other interventions; and 1 study comparing semiannual SDF applications versus a control group. The literature indicates that SDF is a preventive treatment for dental caries in community settings. At concentrations of 30% and 38%, SDF shows potential as an alternative treatment for caries arrest in the primary dentition and permanent first molars. To establish guidelines, more studies are needed to fully assess the effectiveness of SDF and to

  13. Physical exploration for uranium during 1951 in the Silver Reef district, Washington County, Utah

    USGS Publications Warehouse

    Stugard, Frederick

    1954-01-01

    During 1951 a joint exploration program of the most promising uraniferous areas in the Silver Reef district was made by the U.S. Geological Survey and the U.S. atomic Energy Commission. A U.S. Bureau of Mines drill crew, on contract to the Atomic Energy Commission, did 2,450 feet of diamond drilling under the geological supervision of the U.S. Geological Survey. The purpose of the drilling was to delineate broadly the favorable ground for commercial development of the uranium deposits. Ten drill holes were located around Pumpkin Point, which is the northeastern end of Buckeye Reef, to probe for extensions of small ore sheets mined on the Point in fine-grained sandstones of the Chinle formation. Three additional holes were located around Tecumseh Hill to probe for extensions of the small showings of uranium-bearing rocks of Buckeye Reef. Only one trace of uranium mineral was detected in the 13 drill holes by logging of drill cores, gamma-ray logging of the holes, and analysis of many core splits from favorable lithology. Extensive traversing with Geiger counters throughout the district and detailed geologic mapping of areas on Buckeye Reef and on East Reef indicate that the chances of discovering significant uranium deposits in the Silver Reef district are very poor, because of: highly variable lithology, closely faulted structure, and obliteration of the shallow uranium-bearing lenses by silver mining. Most of the available ore in the district was in the Pumpkin Point area and has been mined during 1950 to 1953. No ore reserves can be computed for the district before further development work. The most favorable remaining area in the district is now being explored by the operators with Atomic Energy Commission supervision.

  14. An alternate technique of care using silver fluoride followed by stannous fluoride in the management of root caries in aged care.

    PubMed

    Deutsch, Alan

    2016-01-01

    An alternate technique of care to prevent, arrest and manage root caries using aqueous silver fluoride followed by stannous fluoride (AgF+SnF2) in aged care is demonstrated by three case studies. With increasing age, the inability to maintain ones own oral care from dementia, illness or frailty and polypharmacy induced salivary gland hypofunction will result in dental caries becoming a progessively greater burden for the elderly. Future generations of elders will live longer and need to maintain many more teeth longer than earlier generations. Both silver diamine fluoride (SDF)and AgF+SnF2 arrest and prevent caries and are easy to use in residential aged care facilities. Clinical differences between SDF and AgF+SnF2 are discussed. However, in aged care, AgF+SnF2 may offer advantages over SDF. AgF+SnF2 used to arrest and prevent caries in children can be modified to provide effective but minimally invasive care for an ageing and frail population. These techniques are rapid, inexpensive and nonthreatening suited to treat frail elders, dementia patients exhibiting challenging behaviours and patients with multiple rapidly progressing decay. Silver fluoride, applied before placing glass-ionomer cement (GIC) restorations is an important adjunct to the atraumatic restorative technique and may retard caries reactivation more than GIC used alone.

  15. Antimicrobial and cytotoxicity evaluation of colloidal chitosan - silver nanoparticles - fluoride nanocomposites.

    PubMed

    Freire, Priscila L L; Albuquerque, Allan J R; Farias, Isabela A P; da Silva, Teresinha Gonçalves; Aguiar, Jaciana Santos; Galembeck, André; Flores, Miguel A P; Sampaio, Fabio C; Stamford, Thayza Christina Montenegro; Rosenblatt, Aronita

    2016-12-01

    The present study aimed to evaluate the antimicrobial activity and cytotoxicity of colloidal chitosan - silver nanoparticle - fluoride nanocomposites (CChAgNpFNc), with different silver nanoparticle shapes and sizes. The syntheses of CChAgNpFNc were performed with silver nitrate added to a chitosan solution, addition of a sodium borohydride solution and solid sodium fluoride. Solution of ascorbic acid was added to synthesize larger silver nanoparticles. CChAgNpFNc obtained: S1- 100% spherical, 8.7±3.1nm; S2- 97% spherical, 15.0±7.9nm and 2.5% triangular, 22.2±9.5nm; S3- 77.3% spherical, 31.8±10.4nm, 15.9% triangular, 27.1±10.1nm and 6.8% elliptical, 33.2±7.8nm; and S4- 75.2% spherical, 43.2±14.3nm; 23.3% triangular 38.2±14.8nm, and 1.5% elliptical 38.4±11.6nm. The CChAgNpFNc showed antimicrobial activity against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans, by microdilution technique. The influence on the growth of microorganisms was evaluated using a fluorescence assay, and showed an increasing lag phase and a decreasing log phase. Cytotoxicity was investigated using Artemia salina and MTT assays. The S3 and S4 samples exhibited low cytotoxicity. The S1 and S2 samples inhibited murine macrophages and revealed lethal dose concentrations above 1000mg/mL that were classified as moderately toxic. Thus, CChAgNpFNc are potential options for the control of multiple-drug-resistant microorganisms and do not represent substantial risks to human health. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Antimicrobial efficacy of 3.8% silver diamine fluoride and its effect on root dentin.

    PubMed

    Hiraishi, Noriko; Yiu, Cynthia K Y; King, Nigel M; Tagami, Junji; Tay, Franklin R

    2010-06-01

    This study investigated the use of 3.8% silver diamine fluoride (Ag[NH3]2F) as an antibacterial agent against Enterococcus faecalis biofilms and its ability to penetrate dentinal tubules by the formation of silver salts. Biofilms were generated on membrane filter discs and subjected to 15-minute and 60-minute exposure times with 3.8% Ag(NH3)2F, saturated Ca(OH)2, 5.25% NaOCl (negative control), and 0.9% NaCl (positive control). Cleaned and shaped radicular dentin were applied with Ag(NH3)2F for 24, 48, and 72 hours. The presence of silver salts on the dentin surface was examined using low-pressure scanning electron microscopy. Both NaOCl and Ag(NH3)2F were effective against E. faecalis biofilms, with no significant difference in reduction of microorganisms for both exposure times. Silver deposits were present on 66.5% of the radicular dentin surfaces after 72-hour application of Ag(NH3)2F as simulated interappointment dressings. Penetration of the silver deposits was observed at most 40 microm into dentinal tubules after smear layer removal. Ag(NH3)2F has potential to be used as an antimicrobial root canal irrigant or interappointment dressing, especially in locations in which potential browning/blackening of dentin by metallic silver is not a major concern. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Effect of silver diamine fluoride and potassium iodide on residual bacteria in dentinal tubules.

    PubMed

    Hamama, H H; Yiu, C K; Burrow, M F

    2015-03-01

    This study evaluated the antimicrobial effect of a silver diamine fluoride (SDF)/potassium iodide (KI) product (Riva Star) on the viability of intratubular bacteria. Forty-five dentine discs prepared from caries-free maxillary premolars were randomly divided into nine groups. Group 1 (negative control) contained non-infected sound dentine discs. The remaining discs were infected with Streptococcus mutans suspension and received dentine treatments as follows: Group 2 (positive control), discs were left untreated; Group 3 SDF/KI (Riva Star); Group 4 chlorhexidine (CHX); Group 5 CHX+SDF/KI; Group 6 Carisolv; Group 7 Carisolv+SDF/KI; Group 8 Papacarie, and Group 9 Papacarie+SDF/KI. The discs were then fractured into two halves, stained with fluorescent LIVE/DEAD stain and observed using confocal laser scanning microscopy. SDF/KI exhibited a potent antibacterial effect, as represented by a significantly higher percentage of dead bacteria, in comparison with Carisolv and Papacarie (p<0.05). The application of SDF/KI following Carisolv and Papacarie chemomechanical caries removel gels significantly reduced the viability of intra-tubular bacteria in these groups. The use of the silver diamine fluoride/potassium iodide product is effective in reducing the numbers of S. mutans in dentinal tubules infected with this organism. © 2015 Australian Dental Association.

  18. A systematic review of silver diamine fluoride: Effectiveness and application in older adults.

    PubMed

    Hendre, Amruta D; Taylor, George W; Chávez, Elisa M; Hyde, Susan

    2017-08-15

    This systematic review examines the effectiveness of silver diamine fluoride (SDF) in the management of caries in older adults. Silver diamine fluoride has been extensively researched and proven effective for caries prevention and arrest in children. Limited studies support its effectiveness in adult and older adult populations. Multiple databases were searched according to specified inclusion-exclusion criteria. Quality assessment used modified Centre for Evidence-Based Medicine worksheets. Three randomised controlled trials were identified that addressed the effectiveness of SDF on root caries in older adults, but none addressed coronal caries. Root caries prevented fraction and arrest rate for SDF were significantly higher than placebo. The prevented fraction for caries prevention for SDF compared to placebo was 71% in a 3-year study and 25% in a 2-year study. The prevented fraction for caries arrest for SDF was 725% greater in a 24-month study and 100% greater than placebo in a 30-month study. No severe adverse effects were observed. This systematic review evaluates the use of SDF for both root caries prevention and arrest in older adults. Existing reports of SDF trials support effectiveness in root caries prevention and arrest, remineralization of deep occlusal lesions and treatment of hypersensitive dentin. © 2017 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.

  19. Effect of Silver Diamine Fluoride (SDF) Application on Microtensile Bonding Strength of Dentin in Primary Teeth.

    PubMed

    Wu, Di I; Velamakanni, Saalini; Denisson, Joseph; Yaman, Peter; Boynton, James R; Papagerakis, Petros

    2016-01-01

    The purpose of this study was to investigate the effect of silver diamine fluoride (SDF) on the microtensile bonding strength of resin composite to the dentin of primary molars. Twelve primary molars were randomly assigned to either the control or the SDF groups, and microtensile bonding strength (mTBS) was measured. The surface morphology was evaluated by visual inspection and scanning electron microscopy (SEM) imaging. The mean±(SD) value of mTBS in the control and SDF group was 162.09±81.08 and 139.85±88.53, respectively (P=0.402). SEM images showed that, in the control group, the majority of the fractures occurred at the adhesive-dentin conjunction, while in the SDF group failure mostly occurred within the adhesives. Pretreating dentin with 38 percent silver diamine fluoride does not affect the bonding strength of composite resin to dentin. The fracture patterns observed suggest that bonding strength might be stronger between the adhesive and the SDF-applied dentin. Our data suggest that SDF can be used as a dentin pretreatment prior to resin restoration potentially contributing to secondary caries prevention in primary teeth.

  20. Inhibitory effect of silver diamine fluoride on dentine demineralisation and collagen degradation.

    PubMed

    Mei, May L; Ito, L; Cao, Y; Li, Q L; Lo, Edward C M; Chu, C H

    2013-09-01

    To investigate the inhibitory effects of 38% silver diamine fluoride (SDF) on demineralised dentine. Human dentine blocks were demineralised and allocated to four groups: SF, F, S and W. The blocks in group SF received a topical application of 38% SDF solution (253,900ppm Ag, 44,800ppm F), group F received a 10% sodium fluoride solution (44,800ppm F), group S received a 42% silver nitrate solution (253,900ppm Ag) and group W received deionised water (control). They were subjected to pH cycling using demineralisation solution (pH 5) and remineralisation solution (pH 7) for 8 days. The surface morphology, crystal characteristics, lesion depth and collagen matrix degradation of the specimens were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-CT testing and spectrophotometry with a hydroxyproline assay. The surface morphology under SEM showed evident demineralisation with exposed collagen in groups S and W, but not in group SF. Clusters of granular spherical grains were observed in the cross-sections of specimens in groups SF and F. XRD revealed precipitates of silver chloride in groups SF and S. The mean lesion depths (±SD) of groups SF, F, S and W were 182 ± 32μm, 204 ± 26μm, 259 ± 42μm and 265 ± 40μm, respectively (SDF, F

  1. Physical exploration for uranium during 1951 in the Silver Reef district, Washington County, Utah

    USGS Publications Warehouse

    Stugard, Frederick

    1953-01-01

    During 1951 a joint exploration program of the most promising uraniferous areas in the Silver Reef district was made by the U.S. Geological Survey and the u.S. Atomic Energy Commission.  A U.S. Bureau of Mines drill crew, on contract to the Atomic Energy Commission, did 2,450 feet of diamond drilling under the geological supervision of the U.S. Geological Survey.  The purpose of the drilling was to delineate broadly the favorable ground for commercial development of the uranium depostis.  Ten drill holes were located around Pumpkin Point, which is the northeastern end of Buckeye Reef, to probe for extensions of small ore shootsmined on the Point in fine-grained sandstones of the Chinle formation.  Three additional holes were located around teh Tecumseh Hill to prbe for extensions of the small showings of uranium-bearing rocks of Buckeye Reef.

  2. Facet-mediated growth of silver nanoparticles on biaxial calcium fluoride nanorod arrays

    NASA Astrophysics Data System (ADS)

    Auer, Mathias; Ye, Dexian

    2017-01-01

    The surface orientation of metal nanoparticles is critical to their physical and chemical properties. This study aims on the understanding of the effect of surface orientation as well as heterogeneous epitaxy of metal nanoparticles at an interface between two materials with a large lattice mismatch. Silver nanoparticles of different diameters were grown on arrays of calcium fluoride (CaF2) nanorods using oblique angle deposition as a model system for this study. Scanning electron microscopy and transmission electron microscopy (TEM) imaging were used to verify that the nanoparticles were selectively grown on the desired {111} facets of the nanorod tips. Using selected area diffraction and dark field imaging in TEM, it was shown that the nanoparticles were grown at a (111) orientation at the CaF2 interface with large lattice strains. Thus biaxially textured CaF2 nanorod arrays can be used as a catalytic support.

  3. Evaluation of silver diamine fluoride application in children and factors associated with arrested caries survival

    NASA Astrophysics Data System (ADS)

    Chandra, L.; Rahardjo, A.; Adiatman, M.; Darwita, R.; Maharani, D. A.; Callea, M.

    2017-08-01

    Dental caries is one of the most prevalent infectious diseases in children in Indonesia. Therefore, a solution to overcome caries is needed. Evaluate Silver diamine fluoride (SDF) application for overcoming caries in children and determine factors related to the percentage of arrested caries after SDF application. Cohort study for evaluation and a cross-sectional study; 115 children aged 3-5 years who had active dentin caries were the subjects. Caries risk factors were measured by questionnaires filled out by subjects’ parents. Active caries treated with SDF had odds ratios of 9.9 and 6.8 of being arrested after 3 and 10 months, respectively, when compared with those not treated. Conclusion: SDF is effective in arresting caries and decreasing toothaches suffered by children, thus potentially increasing children’s quality of life.

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

    PubMed

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

    2015-06-01

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

  5. Penetration Potential of a Silver Diamine Fluoride Solution on Dentin Surfaces. An Ex Vivo Study.

    PubMed

    Willershausen, Ines; Schulte, Daniel; Azaripour, Adriano; Weyer, Veronica; Briseño, Benjamin; Willershausen, Brita

    2015-01-01

    Occurrence of open dentinal tubules as a cause of dental hypersensitivity is a very common pnenomenon in patients. The aim of this in vitro study was to assess the effect of a silver diamine fluoride solution (Ag(NH3)2 F) on human dentin samples. A total of five fully retained wisdom teeth were selected for this study. The crowns of the teeth were separated from the roots and the occlusal enamel surface was removed. All dentin samples were treated for 60 seconds with phosphoric acid (36%) and rinsed thoroughly to remove the smear layer. Then the desensitizing agent (Riva Star, SDI; 38% Ag(NH3)2 F) was placed according to the manufacturer's instruction. Three dentin samples were prepared for element analysis using an electron beam microprobe analyzer (JEOL JXA 8900RL). The Ag concentrations in the dentin samples were measured in depths ranging from 5 to 40 μm. The other two dentin samples were vertically fractured and accordingly prepared for visualization with SEM (Zeiss DSM). The application of the desensitizing agent on the dentin areas demonstrated an increased Ag concentration (JEOL JXA 8900RL). On the dentin surface an Ag concentration of 1.7 weight % (? 0.7) was measured, but at a depth of 20 μm only 0.3 weight % (± 0.1) were detected. In depths greater than 40 μm the Ag concentration was below the detection limit. The SEM results showed that deposits could be found in a covering on the dentin layer and in the dentinal tubules to a depth of 20 μm. In this ex vivo study, the effect of silver diamine fluoride on dentin surfaces could be demonstrated. The desensitizing agent formed a film on the dentin surface and in some dentinal tubules deposits were detected. These findings can explain a certain desensitizing effect, but a direct translation to in vivo conditions can only be done with caution.

  6. Silver diamine fluoride and education to prevent and arrest root caries among community-dwelling elders.

    PubMed

    Zhang, W; McGrath, C; Lo, E C M; Li, J Y

    2013-01-01

    Root caries among elderly communities is of growing public health concern globally. This controlled clinical trial investigated the effectiveness of silver diamine fluoride and oral health education in preventing and arresting root caries. Two hundred sixty-six elderly subjects who had at least 5 teeth with exposed root surfaces and did not have serious life-threatening medical diseases were allocated to 3 groups according to a computer-generated random list: group 1 (the control group) received oral hygiene instructions (OHI) annually; group 2 received OHI and silver diamine fluoride (SDF) application annually, and group 3 was given OHI and SDF application annually, plus an oral health education (OHE) programme every 6 months. Two hundred twenty-seven elderly subjects were followed for 24 months. The mean numbers of new root caries surfaces in groups 1, 2 and 3 were 1.33, 1.00 and 0.70, respectively (ANOVA, p < 0.05). Group 3 had fewer root surfaces with new caries than group 1 (Scheffé multiple-comparison test, p < 0.05). The mean numbers of arrested root caries surfaces in groups 1, 2 and 3 were 0.04, 0.28 and 0.33, respectively (ANOVA, p < 0.01). Group 3 and group 2 had a greater number of active root caries surfaces which became arrested than group 1 (Scheffé multiple-comparison test, p < 0.05). Annual application of SDF together with biannual OHE was effective in preventing new root caries and arresting root caries among community-dwelling elderly subjects. Copyright © 2013 S. Karger AG, Basel.

  7. Mechanisms of silver diamine fluoride on arresting caries: a literature review.

    PubMed

    Zhao, Irene Shuping; Gao, Sherry Shiqian; Hiraishi, Noriko; Burrow, Michael Francis; Duangthip, Duangporn; Mei, May Lei; Lo, Edward Chin-Man; Chu, Chun-Hung

    2017-05-21

    To review the evidence regarding the mechanisms of silver diamine fluoride (SDF) for arresting caries. A literature search was conducted using the keywords silver diamine fluoride, and its alternative names, in seven databases: PubMed, Embase and Scopus (English); China National Knowledge Infrastructure (Chinese); Bilioteca Virtual em Saude (Portuguese); Biblioteca Virtual en Salud Espana (Spanish); and Ichushi-Web (Japanese). The titles and abstracts were screened. Full texts were retrieved for publications that studied mechanisms of actions of SDF, including its effects on remineralisation of carious lesions and on cariogenic bacteria. A total of 1,123 publications were identified. Twenty-nine articles were included and they investigated the effect of SDF on cariogenic bacteria and dental hard tissues. Eleven studies investigated the antibacterial properties of SDF. They found that SDF was bactericidal to cariogenic bacteria, mainly Streptococcus mutans. It inhibited the growth of cariogenic biofilms on teeth. Twenty studies reported the remineralisation of demineralised enamel or dentine by SDF. They found that mineral loss of demineralised enamel and dentine was reduced after SDF treatment. A highly mineralised surface rich in calcium and phosphate was formed on arrested carious lesions. Four studies examined the effect of SDF on dentine collagen. They found that SDF inhibited collagenases (matrix metalloproteinases and cysteine cathepsins) and protected dentine collagen from destruction. SDF is a bactericidal agent and reduces the growth of cariogenic bacteria. It inhibits demineralisation and promotes the remineralisation of demineralised enamel and dentine. It also hampers degradation of the dentine collagen. © 2017 FDI World Dental Federation.

  8. Promoting caries arrest in children with silver diamine fluoride: a review.

    PubMed

    Chu, C H; Lo, E C M

    2008-01-01

    Although there has been a decrease in the prevalence and the severity of dental caries in children over the past few decades, the benefits have not been equally shared by many low-income or underserved children in many industrialised countries, or children in developing countries. Dental caries is still the most common and challenging dental disease in children for a clinician to treat. Silver diamine fluoride (SDF) has been in use to arrest dental caries in many countries. A 38% (44,800 ppm fluoride ions) SDF solution is commonly used to arrest caries in primary teeth of children, especially those children who are young and difficult to manage. Application of SDF to arrest dental caries is a non-invasive procedure that is quick and simple to use. However, it stains the carious teeth and turns the arrested caries black. It also has an unpleasant metallic taste that is not liked by patients, especially children. The low cost of SDF and its simplicity in application suggest that SDF is an appropriate therapeutic agent for use in community dental health projects. Reports of available studies found no severe pulpal damage after SDF application. The current literature suggests that SDF can be an effective agent in preventing new caries and in arresting dental caries in the primary teeth of the children. It can be used to arrest caries progression in very young children who are less cooperative, and it allows definitive restoration to be performed when they grow older and become more receptive to dental procedures.

  9. Silver Diamine Fluoride remineralized artificial incipient caries in permanent teeth after bacterial pH-cycling in-vitro.

    PubMed

    Punyanirun, Kulnipa; Yospiboonwong, Thanida; Kunapinun, Thansinee; Thanyasrisung, Panida; Trairatvorakul, Chutima

    2017-09-13

    To investigate the remineralizing effect of 38% silver diamine fluoride (SDF) application on enamel artificial caries in adjunct to 1000ppm fluoride toothpaste compared with fluoride toothpaste alone by analyzing the mineral density, depth of remineralization, and remineralization percentage of the lesions. Eighteen artificial caries slabs were created from the proximal surfaces of nine chemically demineralized premolars. The slabs were scanned by Micro-Computed Tomography (Micro-CT) to determine the baseline mineral density of the initial lesions and randomly allocated into 2 groups. The test group was applied with 38% SDF in adjunct to fluoride toothpaste and the control group was treated with fluoride toothpaste alone. The specimens underwent bacterial pH-cycling for 5 d and were re-evaluated using Micro-CT. The pre-treatment and post-treatment mineral densities were plotted and the areas under the curves were used to calculate the remineralization percentage of both groups. Mineral density significantly increased in both groups after pH-cycling (p<0.05) although to different depths (control group=260μm, test group=300μm). The test group demonstrated a significantly higher mineral density to a depth of 120μm and higher remineralization percentage (p<0.05) compared with the control group. The adjunctive use of 38% SDF enhances the remineralization of initial carious lesions based on mineral density, depth, and remineralization percentage compared with the use of 1000ppm fluoride toothpaste alone. SDF might be used as an adjunct to fluoride toothpaste to remineralize incipient caries lesions on smooth tooth surfaces. In non-compliant patients, the application of 38% SDF might be used as an adjunct to fluoride toothpaste, to remineralize incipient caries lesions of permanent teeth where esthetics is not a concern. 270W. Copyright © 2017. Published by Elsevier Ltd.

  10. Anti-microbial efficiency of silver diamine fluoride as an endodontic medicament – An ex vivo study

    PubMed Central

    Mathew, Vinod B.; Madhusudhana, Koppolu; Sivakumar, Nuvulla; Venugopal, Thangala; Reddy, Redderu K.

    2012-01-01

    Context: Antisepsis achieved through appropriate use of irrigants is essential for endodontic success. Identification of newer anti-bacterial agents gives alternatives to clean the canal as eradication of the infection prior to obturation does affect prognosis. Objective: Comparison of the anti-bacterial action of 3.8% silver diamine fluoride and 2% chlorhexidine gluconate against Enterococcus faecalis in root canals. Materials and Methods: Forty-four single-rooted teeth were decoronated, and the root section was enlarged with peeso-reamer (No: 3) to standardize length and diameter. The samples were then autoclaved and divided into two study groups and two control groups. Enterococcus faecalis ATCC 29212 was inoculated into all test samples for 72 hours. The samples were enlarged with peeso-reamer (No: 5) after placement of respective medicament for 24 hours. Shavings were collected and inoculated on Brain Heart Infusion agar for 24 hrs to measure the colony forming units. Results: Both 3.8% silver diamine fluoride and 2% chlorhexidine showed a superior capacity to sterilize the root canals than control groups. Conclusion: The use of silver diamine fluoride as an endodontic irrigant is feasible as it can effectively remove the microbes present in the canal and circumpulpal dentin. PMID:23293478

  11. An ex vivo study of arrested primary teeth caries with silver diamine fluoride therapy.

    PubMed

    Mei, May L; Ito, L; Cao, Y; Lo, Edward C M; Li, Q L; Chu, C H

    2014-04-01

    This ex vivo study compared the physico-chemical structural differences between primary carious teeth biannually treated with silver diamine fluoride (SDF) and carious teeth without such treatment. Twelve carious primary upper-central incisors were collected from 6-year-old children. Six teeth had arrested caries after 24-month biannual SDF applications and 6 had active caries when there was no topical fluoride treatment. The mineral density, elemental contents, surface morphology, and crystal characteristics were assessed by micro-computed tomography (micro-CT), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Micro-CT examination revealed a superficial opaque band approximately 150μm on the arrested cavitated dentinal lesion. This band was limited in the active carious lesion. EDX examination detected a higher intensity of calcium and phosphate of 150μm in the surface zone than in the inner zone, but this zone was restricted in the active cavitated dentinal lesion. SEM examination indicated that the collagens were protected from being exposed in the arrested cavitated dentinal lesion, but were exposed in the active cavitated dentinal lesion. TEM examination suggested that remineralised hydroxyapatites were well aligned in the arrested cavitated dentinal lesion, while those in the active cavitated dentinal lesion indicated a random apatite arrangement. A highly remineralised zone rich in calcium and phosphate was found on the arrested cavitated dentinal lesion of primary teeth with an SDF application. The collagens were protected from being exposed in the arrested cavitated dentinal lesion. Clinical SDF application positively influences dentine remineralisation. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. URANIUM RECOVERY PROCESS

    DOEpatents

    Bailes, R.H.; Long, R.S.; Olson, R.S.; Kerlinger, H.O.

    1959-02-10

    A method is described for recovering uranium values from uranium bearing phosphate solutions such as are encountered in the manufacture of phosphate fertilizers. The solution is first treated with a reducing agent to obtain all the uranium in the tetravalent state. Following this reduction, the solution is treated to co-precipitate the rcduced uranium as a fluoride, together with other insoluble fluorides, thereby accomplishing a substantially complete recovery of even trace amounts of uranium from the phosphate solution. This precipitate usually takes the form of a complex fluoride precipitate, and after appropriate pre-treatment, the uranium fluorides are leached from this precipitate and rccovered from the leach solution.

  13. Electrical behavior and positive temperature coefficient effect of graphene/polyvinylidene fluoride composites containing silver nanowires

    PubMed Central

    2014-01-01

    Polyvinylidene fluoride (PVDF) composites filled with in situ thermally reduced graphene oxide (TRG) and silver nanowire (AgNW) were prepared using solution mixing followed by coagulation and thermal hot pressing. Binary TRG/PVDF nanocomposites exhibited small percolation threshold of 0.12 vol % and low electrical conductivity of approximately 10-7 S/cm. Hybridization of TRGs with AgNWs led to a significant improvement in electrical conductivity due to their synergistic effect in conductivity. The bulk conductivity of hybrids was higher than a combined total conductivity of TRG/PVDF and AgNW/PVDF composites at the same filler loading. Furthermore, the resistivity of hybrid composites increased with increasing temperature, giving rise to a positive temperature coefficient (PTC) effect at the melting temperature of PVDF. The 0.04 vol % TRG/1 vol % AgNW/PVDF hybrid exhibited pronounced PTC behavior, rendering this composite an attractive material for making current limiting devices and temperature sensors. PMID:25114661

  14. Electronic solution spectra for uranium and neptunium in oxidation states (III) to (VI) in anhydrous hydrogen fluoride

    SciTech Connect

    Baluka, M.; Edelstein, N.; O'Donnell, T. A.

    1981-10-01

    In this paper, spectra have been recorded for solutions in anhydrous hydrogen fluoride (AHF) of uranium and neptunium in oxidation states III to VI. The spectra for U(III), Np(III), and Np(IV) in AHF are very similar to those in acidified aqueous solution, but that for U(IV) suggests that the cationic species is UF22+. The AHF spectra for the elements in oxidation states V and VI are not comparable with those of the formally analogous aqueous solutions, where the elements exist as well-defined dioxo cations. Nonetheless, the AHF spectra can be related to spectra in the gas phase, in the solid state or in nonaqueous solvents for each element in its appropriate oxidation state.

  15. Effect of temperature on the complexation of Uranium(VI) with fluoride in aqueous solutions

    SciTech Connect

    Tian, Guoxin; Rao, Linfeng

    2009-05-18

    Complexation of U(VI) with fluoride at elevated temperatures in aqueous solutions was studied by spectrophotometry. Four successive complexes, UO{sub 2}F{sup +}, UO{sub 2}F{sub 2}(aq), UO{sub 2}F{sub 3}{sup -}, and UO{sub 2}F{sub 4}{sup 2-}, were identified, and the stability constants at 25, 40, 55, and 70 C were calculated. The stability of the complexes increased as the temperature was elevated. The enthalpies of complexation at 25 C were determined by microcalorimetry. Thermodynamic parameters indicate that the complexation of U(VI) with fluoride in aqueous solutions at 25 to 70 C is slightly endothermic and entropy-driven. The Specific Ion Interaction (SIT) approach was used to obtain the thermodynamic parameters of complexation at infinite dilution. Structural information on the U(VI)/fluoride complexes was obtained by extended X-ray absorption fine structure spectroscopy.

  16. Antibacterial effects of silver diamine fluoride on multi-species cariogenic biofilm on caries

    PubMed Central

    2013-01-01

    Backgrounds Silver diamine fluoride (SDF) has clinical success in arresting dentin caries, this study aimed to investigate its mechanism of action. Methods Using a computer-controlled artificial mouth, we studied the effect of 38% SDF on cariogenic biofilms and dentin carious lesions. We used five common cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus rhamnosus and Actinomyces naeslundii) to form a cariogenic biofilm that generated carious lesions with a depth of approximately 70 um on human dentin blocks. We applied 38% SDF to the lesions in the test group and water to those in the control group. The blocks were incubated in the artificial mouth for 21 days before evaluation. Microbial kinetics, architecture, viability and distribution were evaluated every 7 days using colony forming unit (CFU), scanning electron microscopy and confocal laser scanning microscopy. The physical properties of the carious lesions were evaluated with microhardness testing, energy dispersive spectroscopy (EDS) and Fourier transform infra-red spectroscopy (FTIR). Results The CFU results revealed fewer colony forming units in the test group compared with the control group (p < 0.01). Scanning electron microscopy and confocal microscopy showed less bacterial growth in the test group, and confluent cariogenic biofilm in the control group (p < 0.01). The microhardness and weight percentages of calcium and phosphorus in the test group from the outermost 50mum were higher than in the control group (p < 0.05). EDS showed that calcium and phosphous were higher in outer 50 mum in test groups than in the control FTIR revealed less exposed collagen I in the test lesions compared with the control group (p < 0.01). Conclusions 38% SDF inhibits multi-species cariogenic biofilm formation on dentin carious lesions and reduces the demineralization process. PMID:23442825

  17. In vitro antibacterial activity of silver diamine fluoride in different concentrations.

    PubMed

    de Almeida, Leopoldina de F D; Cavalcanti, Yuri W; Valença, Ana M G

    2011-01-01

    The antibacterial activity of Silver Diamine Fluoride - SDF -(Cariestop), at commercial concentrations of 12% and 30%, was evaluated against clinical and pattern strains (ATCC 25175) of S. mutans. Clinical isolates were obtained from the saliva of six children attending the Pediatric Dentistry Clinic UFPB, being grouped as follows: GI- low risk and caries activity, GII- high risk and caries activity. Once sown, the strains were isolated from Mitis-Salivarius Agar and divided into seven groups - M1 (pattern strain) to M7. The antibacterial activity was determined by maximum inhibitory dilution (MID) by the agar diffusion method, using serial dilutions (1:1 to 1:32) and the pure formulations of SDF and chlorhexidine 0.12% (positive control). After incubation, the inhibition zones were measured. The bactericidal and bacteriostatic actions of pure substances and in their respective MIDs were evaluated by test of germicidal power using glass specimens, after inoculation by the strains and incubation for 24 hours in BHI broth. Each specimen was exposed to chlorhexidine and to SDF for 30s, 3min, 30min and 1h, then incubated for 24 h in BHI broth. The samples were subcultured in Mitis-Salivarius Agar to evaluate the bactericidal or bacteriostatic activity of the substances. The data were analyzed in a comparative-descriptive method. The Cariestop 30% was effective until the last dilution (1:32) on all strains. For Cariestop 12%, the MIDs corresponded to last dilution (1:32) in almost all samples, except for M3 (1:8). Chlorhexidine showed DIM in the last concentrations (1:32) on five samples, and in the concentration 1:8 for M3 and M7. As evidence of the germicidal power the substances had bactericidal activity at all times analyzed. It was concluded that the cariostatic showed antibacterial activity when compared to chlorhexidine and these two substances presented bactericidal action against the strains at all contact times.

  18. Effect and acceptance of silver diamine fluoride treatment on dental caries in primary teeth.

    PubMed

    Clemens, Jennifer; Gold, Jaana; Chaffin, Jeffrey

    2017-07-27

    Silver diamine fluoride (SDF) treatment has been identified as a potential solution to address the dental public health issues of untreated dental caries and insufficient access to care. The current study assessed the effectiveness of 38 percent SDF in arresting active dental caries lesions and in reducing or preventing associated dental pain and infections in young, at-risk children. We enrolled 32 children aged 2-5 years with 118 active caries lesions in primary teeth from a community dental clinic in Oregon. After baseline examinations, carious lesions were treated with 1-2 applications of 38 percent SDF. Children were re-evaluated at 3-week and 3-month recalls to assess color and consistency changes in lesions (soft/hard). Parents were interviewed regarding symptoms of pain or infection and were surveyed regarding subjective feelings about SDF. Of 102 lesions (16 excluded from analyses), 100 were found to be arrested at first recall and all at second recall. The duration of SDF application was not associated with arrest of decay (P = 0.68). No incidence of pain or infection of an SDF-treated tooth was recorded. Parental impression of ease of application, taste, and esthetics was favorable. Our results suggested SDF was effective in arresting active caries lesions in primary teeth in young children and was well accepted by parents. SDF offers an easy and highly efficient nonsurgical alternative treatment to traditional restorative dental treatment in young children, and it has great potential to aid the dental public health community to address dental caries in at-risk populations. © 2017 American Association of Public Health Dentistry.

  19. Antibacterial effects of silver diamine fluoride on multi-species cariogenic biofilm on caries.

    PubMed

    Mei, May Lei; Li, Quan-li; Chu, Chun-Hung; Lo, Edward Chin-Man; Samaranayake, Lakshman Perera

    2013-02-26

    Silver diamine fluoride (SDF) has clinical success in arresting dentin caries, this study aimed to investigate its mechanism of action. Using a computer-controlled artificial mouth, we studied the effect of 38% SDF on cariogenic biofilms and dentin carious lesions. We used five common cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus rhamnosus and Actinomyces naeslundii) to form a cariogenic biofilm that generated carious lesions with a depth of approximately 70 um on human dentin blocks. We applied 38% SDF to the lesions in the test group and water to those in the control group. The blocks were incubated in the artificial mouth for 21 days before evaluation. Microbial kinetics, architecture, viability and distribution were evaluated every 7 days using colony forming unit (CFU), scanning electron microscopy and confocal laser scanning microscopy. The physical properties of the carious lesions were evaluated with microhardness testing, energy dispersive spectroscopy (EDS) and Fourier transform infra-red spectroscopy (FTIR). The CFU results revealed fewer colony forming units in the test group compared with the control group (p < 0.01). Scanning electron microscopy and confocal microscopy showed less bacterial growth in the test group, and confluent cariogenic biofilm in the control group (p < 0.01). The microhardness and weight percentages of calcium and phosphorus in the test group from the outermost 50mum were higher than in the control group (p < 0.05). EDS showed that calcium and phosphous were higher in outer 50 mum in test groups than in the control FTIR revealed less exposed collagen I in the test lesions compared with the control group (p < 0.01). 38% SDF inhibits multi-species cariogenic biofilm formation on dentin carious lesions and reduces the demineralization process.

  20. Effect of silver diamine fluoride on microtensile bond strength to dentin.

    PubMed

    Quock, R L; Barros, J A; Yang, S W; Patel, S A

    2012-01-01

    The aim of this in vitro study was to investigate the effect of the cariostatic and preventive agent silver diamine fluoride (SDF) on the microtensile bond strength of resin composite to dentin. Forty-two caries-free, extracted molars were flattened occlusally and apically using a diamond saw, and the exposed occlusal dentin was polished with a series of silicon carbide papers, all under water irrigation. The teeth were then randomly divided into six groups of seven teeth each that were treated as follows: 1) Peak SE self-etch bonding agent; 2) 12% SDF + Peak SE; 3) 38% SDF + Peak SE; 4) Peak LC etch-and-rinse bonding agent; 5) 12% SDF + Peak LC; and 6) 38% SDF + Peak LC. Four-millimeter buildups of Amelogen Plus were incrementally placed on all teeth; after a 24-hour storage period in distilled water, the specimens were sectioned perpendicular to the adhesive interface to produce beams of cross-sectional surface area measuring approximately 1 mm(2). The beams were placed on a microtensile testing machine, which utilized a single-speed pump motor and force gauge at 20 kgf × 0.01 second to record maximum tensile force before failure occurred. Two-way analysis of variance and post hoc Tukey tests were performed to compare the effects of the SDF on microtensile bond strength, with statistical significance set at α = 0.05. None of the experimental groups treated with different concentrations of SDF showed a significant difference in bond strength compared to the control groups, and there was no significant difference in bond strength between self-etch and etch-and-rinse groups. However, the effect of SDF on self-etch bonded teeth compared to etch-and-rinse bonded teeth was statistically significant (p=0.0363), specifically at the 12% concentration. SDF does not adversely affect the bond strength of resin composite to noncarious dentin.

  1. Randomized Clinical Trial of 12% and 38% Silver Diamine Fluoride Treatment.

    PubMed

    Fung, M H T; Duangthip, D; Wong, M C M; Lo, E C M; Chu, C H

    2017-08-01

    This 30-mo randomized clinical trial compared the effectiveness of 2 concentrations (12% or 38%) of silver diamine fluoride (SDF) and 2 periodicity of application (once or twice a year) in arresting cavitated dentin caries in primary teeth. Children aged 3 to 4 y who had at least 1 active cavitated caries lesion were enrolled and randomly allocated into 4 groups for intervention. Group 1 had 12% SDF applied annually (every 12 mo), group 2 had 12% SDF applied semiannually (every 6 mo), group 3 had 38% SDF applied annually, and group 4 had 38% SDF applied semiannually. Clinical examinations were performed semiannually in kindergarten by a single examiner to investigate whether the SDF-treated caries became arrested. A total of 888 children with 4,220 decayed tooth surfaces received SDF application at baseline, and 799 (90.0%) children with 3,790 surfaces (89.8%) were evaluated at the 30-mo examination. The caries arrest rates were 55.2%, 58.6%, 66.9%, and 75.7% for groups 1, 2, 3, and 4, respectively ( P < 0.001). Caries treated with 38% SDF had a higher chance of becoming arrested than those treated with 12% SDF (odds ratio [OR], 1.98; 95% confidence interval [CI], 1.51-2.60, P < 0.001). The interaction between frequency of SDF application and visible plaque index (VPI) score was significant ( P = 0.017). Among those children who received annual SDF application, children with a higher VPI score had a lower chance to have their caries become arrested (OR, 0.59, 95% CI, 0.49-0.72). In conclusion, SDF at a concentration of 38% is more effective than that of 12% in arresting active caries in primary teeth. For children with poor oral hygiene, caries arrest rate of SDF treatment can be increased by increasing the frequency of application from annually to semiannually ( ClinicalTrials.gov NCT02385474).

  2. Silver diamine fluoride and glass ionomer differentially remineralize early caries lesions, in situ.

    PubMed

    Nantanee, Ratichanok; Santiwong, Busayarat; Trairatvorakul, Chutima; Hamba, Hidenori; Tagami, Junji

    2016-07-01

    The aim of the present study was to evaluate the percent mean mineral density (MD) change of early caries lesions after the application of silver diamine fluoride (SDF) or glass ionomer cement (GIC). This double-blind, crossover study involved two experimental phases of 28 days each. Thirty-two pairs of enamel slabs were created from the proximal surfaces of 16 premolars. Each pair of artificial carious slabs was randomly divided into the control or test group (38 % SDF or GIC). The slabs were attached to orthodontic brackets and bonded to the maxillary first permanent molars of 16 subjects for 28 days. After a 7-day washout period between phases, the subjects received the other material for the second phase. The mean MD of the lesions was measured by microcomputed tomography. SDF yielded a percent mean MD increase at a depth of 0-84 μm, although increase in the GIC group was observed at a depth of 24-108 μm. The percent mean MD changes of the SDF and GIC groups were similar (p = 0.100) and significantly higher than in control (p < 0.001, p = 0.003, respectively). The two materials increased the percent mean MD change of early proximal caries lesions to a similar extent, but with different spatial patterns. Due to deeper level of GIC remineralization, the refractive index of the GIC applied enamel might be closer to sound enamel. Hence, GIC is recommended for remineralization of anterior teeth. SDF staining makes it unsuitable for use in anterior teeth; thus, it is reserved for use in posterior teeth.

  3. Calcium fluoride window mounting

    NASA Astrophysics Data System (ADS)

    Berger, D. Douglas

    1982-10-01

    A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.

  4. Pulp response to high fluoride releasing glass ionomer, silver diamine fluoride, and calcium hydroxide used for indirect pulp treatment: An in-vivo comparative study

    PubMed Central

    Korwar, Atish; Sharma, Sidhartha; Logani, Ajay; Shah, Naseem

    2015-01-01

    Aims and Objectives: The study aims at determining pulp response of two high fluoride releasing materials silver diamine fluoride (SDF) and Type VII glass ionomer cement (GIC) when used as indirect pulp treatment (IPT) materials. Materials and Methods: Deep Class V cavities were made on four first premolars indicated for extraction for orthodontic reasons. SDF, Type VII GIC, and calcium hydroxide base are given in three premolars, and one is kept control. Premolars were extracted 6 weeks after the procedure and subjected to histopathological examination to determine the pulp response. The results were analyzed using Chi-square test. Results: No inflammatory changes were observed in any of the groups. Significantly more number of specimens in SDF and Type VII GIC groups showed tertiary dentin deposition (TDD) when compared to control group. No significant difference was seen in TDD when intergroup comparison was made. Odontoblasts were seen as short cuboidal cells with dense basophilic nucleus in SDF and Type VII GIC group. Conclusion: The study demonstrated TDD inducing ability of SDF and Type VII GIC and also established the biocompatibility when used as IPT materials. PMID:26321822

  5. Pulp response to high fluoride releasing glass ionomer, silver diamine fluoride, and calcium hydroxide used for indirect pulp treatment: An in-vivo comparative study.

    PubMed

    Korwar, Atish; Sharma, Sidhartha; Logani, Ajay; Shah, Naseem

    2015-01-01

    The study aims at determining pulp response of two high fluoride releasing materials silver diamine fluoride (SDF) and Type VII glass ionomer cement (GIC) when used as indirect pulp treatment (IPT) materials. Deep Class V cavities were made on four first premolars indicated for extraction for orthodontic reasons. SDF, Type VII GIC, and calcium hydroxide base are given in three premolars, and one is kept control. Premolars were extracted 6 weeks after the procedure and subjected to histopathological examination to determine the pulp response. The results were analyzed using Chi-square test. No inflammatory changes were observed in any of the groups. Significantly more number of specimens in SDF and Type VII GIC groups showed tertiary dentin deposition (TDD) when compared to control group. No significant difference was seen in TDD when intergroup comparison was made. Odontoblasts were seen as short cuboidal cells with dense basophilic nucleus in SDF and Type VII GIC group. The study demonstrated TDD inducing ability of SDF and Type VII GIC and also established the biocompatibility when used as IPT materials.

  6. JACKETING URANIUM

    DOEpatents

    Saller, H.A.; Keeler, J.R.

    1959-07-14

    The bonding to uranium of sheathing of iron or cobalt, or nickel, or alloys thereof is described. The bonding is accomplished by electro-depositing both surfaces to be joined with a coating of silver and amalgamating or alloying the silver layer with mercury or indium. Then the silver alloy is homogenized by exerting pressure on an assembly of the uranium core and the metal jacket, reducing the area of assembly and heating the assembly to homogenize by diffusion.

  7. Adhesiveness of glass ionomer cement containing tannin-fluoride preparation (HY agent) to dentin--an evaluation of adding various ratios of HY agent and combination with application diammine silver fluoride.

    PubMed

    Yamaga, M; Koide, T; Hieda, T

    1993-06-01

    We bonded a glass ionomer cement (GIC) containing various amounts of incorporated tannin-fluoride preparation (HY agent) to bovine dentin and investigated the effect of the ratio of incorporated preparations and the changes in bond strength over time. HY agent was incorporated into the powder at 0% (HY0), 1.5% (HY1.5), 5.0% (HY5), and 10.0% (HY10) by weight. The shear bond strength and percent of the cohesive failure were measured. Similar tests were performed on samples where diammine silver fluoride was applied to the dentin prior to placing the cement. It was found that the bond strength on the first day was increased by incorporating 1.5% of the HY agent in the GIC. The combined use of diammine silver fluoride increased the bond strength of the GIC.

  8. Process for electroslag refining of uranium and uranium alloys

    DOEpatents

    Lewis, P.S. Jr.; Agee, W.A.; Bullock, J.S. IV; Condon, J.B.

    1975-07-22

    A process is described for electroslag refining of uranium and uranium alloys wherein molten uranium and uranium alloys are melted in a molten layer of a fluoride slag containing up to about 8 weight percent calcium metal. The calcium metal reduces oxides in the uranium and uranium alloys to provide them with an oxygen content of less than 100 parts per million. (auth)

  9. Geology of the area adjacent to the Free Enterprise uranium-silver Mine, Boulder District, Jefferson County, Montana

    USGS Publications Warehouse

    Roberts, W.A.; Gude, A.J.

    1952-01-01

    Uranium minerals.occur in pods associated with cryptocrystalline silica, silver minerals, and scattered sulfide mineral grains in a hydrothermal vein that cuts quartz monzonite and alaskite at the Free Enterprise mine, 2 miles west of Boulder, Mont. The Free Enterprise vein is one of many silicified reef-like structures in this area, most of which trend about N. 60° E. The cryptocrystalline silica zones of the area are lenticular and are bordered by an altered zone where quartz monzonite is the wall rock. No alteration was noticed where alaskite is adjacent to silica zones. No uranium minerals were observed at the surface, but radioactivity anomalies were noted at 57 outcrops. Underground mining has shown that leaching by downward percolating waters has removed most of the uranium from the near-surface part of the Free Enterprise vein and probably has enriched slightly, parts of the vein and the adjacent wall rock from the bottom of the leached zone to the ground-water level. It is possible that other veins that show low to moderate radioactivity at the surface may contain significant concentrations of uranium minerals at relatively shallow depth. The quartz monzonite appears to be a more favorable host rock for the cryptocrystalline silica and associated uranium minerals than the alaskite. The alaskite occurs as vertical_dikes plug-like masses, and as irregularly shaped, gently dipping masses that are believed to have been intruded into open fractures formed during the cooling of the quartz monzonite.

  10. Direct electrochemical reduction of solid uranium oxide in molten fluoride salts

    NASA Astrophysics Data System (ADS)

    Gibilaro, Mathieu; Cassayre, Laurent; Lemoine, Olivier; Massot, Laurent; Dugne, Olivier; Malmbeck, Rikard; Chamelot, Pierre

    2011-07-01

    The direct electrochemical reduction of UO 2 solid pellets was carried out in LiF-CaF 2 (+2 mass.% Li 2O) at 850 °C. An inert gold anode was used instead of the usual reactive sacrificial carbon anode. In this case, oxidation of oxide ions present in the melt yields O 2 gas evolution on the anode. Electrochemical characterisations of UO 2 pellets were performed by linear sweep voltammetry at 10 mV/s and reduction waves associated to oxide direct reduction were observed at a potential 150 mV more positive in comparison to the solvent reduction. Subsequent, galvanostatic electrolyses runs were carried out and products were characterised by SEM-EDX, EPMA/WDS, XRD and microhardness measurements. In one of the runs, uranium oxide was partially reduced and three phases were observed: nonreduced UO 2 in the centre, pure metallic uranium on the external layer and an intermediate phase representing the initial stage of reduction taking place at the grain boundaries. In another run, the UO 2 sample was fully reduced. Due to oxygen removal, the U matrix had a typical coral-like structure which is characteristic of the pattern observed after the electroreduction of solid oxides.

  11. Uranium*

    NASA Astrophysics Data System (ADS)

    Grenthe, Ingmar; Drożdżyński, Janusz; Fujino, Takeo; Buck, Edgar C.; Albrecht-Schmitt, Thomas E.; Wolf, Stephen F.

    Uranium compounds have been used as colorants since Roman times (Caley, 1948). Uranium was discovered as a chemical element in a pitchblende specimen by Martin Heinrich Klaproth, who published the results of his work in 1789. Pitchblende is an impure uranium oxide, consisting partly of the most reduced oxide uraninite (UO2) and partly of U3O8. Earlier mineralogists had considered this mineral to be a complex oxide of iron and tungsten or of iron and zinc, but Klaproth showed by dissolving it partially in strong acid that the solutions yielded precipitates that were different from those of known elements. Therefore he concluded that it contained a new element (Mellor, 1932); he named it after the planet Uranus, which had been discovered in 1781 by William Herschel, who named it after the ancient Greek deity of the Heavens.

  12. PREPARATION OF URANIUM HEXAFLUORIDE

    DOEpatents

    Lawroski, S.; Jonke, A.A.; Steunenberg, R.K.

    1959-10-01

    A process is described for preparing uranium hexafluoride from carbonate- leach uranium ore concentrate. The briquetted, crushed, and screened concentrate is reacted with hydrogen fluoride in a fluidized bed, and the uranium tetrafluoride formed is mixed with a solid diluent, such as calcium fluoride. This mixture is fluorinated with fluorine and an inert diluent gas, also in a fluidized bed, and the uranium hexafluoride obtained is finally purified by fractional distillation.

  13. An improved fluorimeter for the determination of uranium in fluoride melts

    USGS Publications Warehouse

    Fletcher, Mary H.; May, Irving

    1950-01-01

    The Model R fluorimeter has been modified to increase its stability and sensitivity. The new instrument* is about ten times as sensitive as the original fluorimeter, but it can also be employed conveniently at a sensitivity level comparable to or less than that of the Model R fluorimeter. *The modified fluorimeter described here was developed in the latter half of 1948 and has since been in constant use in the laboratory for routine analysis. Although it is now being superseded to a large extent by a more recently developed transmission fluorimeter, the modified fluorimeter is a very useful tool for many types of analysis. (Fletcher, M. H., May, Irving, and Slavin, Morris, A transmission fluorimeter for use in the fluorimetric method of analysis for uranium: Trace Elements Investigations Report 104, August 1949.)

  14. Randomized clinical trial on effectiveness of silver diamine fluoride and glass ionomer in arresting dentine caries in preschool children.

    PubMed

    Zhi, Qing Hui; Lo, Edward Chin Man; Lin, Huan Cai

    2012-11-01

    To compare the effectiveness of annual topical application of silver diamine fluoride (SDF) solution, semi-annual topical application of SDF solution, and annual application of a flowable high fluoride-releasing glass ionomer in arresting active dentine caries in primary teeth. A total of 212 children, aged 3-4 years, were randomly allocated to one of three groups for treatment of carious dentine cavities in their primary teeth: Gp1-annual application of SDF, Gp2-semi-annual application of SDF, and Gp3-annual application of glass ionomer. Follow-up examinations were carried out every six months to assess whether the treated caries lesions had become arrested. After 24 months, 181 (85%) children remained in the study. The caries arrest rates were 79%, 91% and 82% for Gp1, Gp2 and Gp3, respectively (p=0.007). In the logistic regression model using GEE to adjust for clustering effect, higher caries arrest rates were found in lesions treated in Gp2 (OR=2.98, p=0.007), those in anterior teeth (OR=5.55, p<0.001), and those in buccal/lingual smooth surfaces (OR=15.6, p=0.004). Annual application of either SDF solution or high fluoride-releasing glass ionomer can arrest active dentine caries. Increasing the frequency of application to every 6 months can increase the caries arrest rate of SDF application. Arrest of active dentine caries in primary teeth by topical application of SDF solution can be enhanced by increasing the frequency of application from annually to every 6 months, whereas annual paint-on of a flowable glass ionomer can also arrest active dentine caries and may provide a more aesthetic outcome. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Arresting simulated dentine caries with adjunctive application of silver nitrate solution and sodium fluoride varnish: an in vitro study.

    PubMed

    Zhao, Irene Shuping; Mei, May Lei; Li, Quan-Li; Lo, Edward Chin Man; Chu, Chun-Hung

    2017-08-01

    The aim of this in vitro study was to assess the ability of silver nitrate solution, followed by sodium fluoride varnish, to arrest caries. Dentine slices were prepared and demineralised. Each slice was cut into three specimens for three groups (SF, SDF and W). Specimens of the SF group received topical application of 25% silver nitrate solution followed by 5% sodium fluoride varnish. The SDF group received topical application of 38% silver diamine fluoride solution (positive control). Specimens of the W group received deionised water (negative control). All specimens were subjected to pH cycling for 8 days. Dentine surface morphology, crystal characteristics, carious lesion depth and collagen matrix degradation were evaluated by scanning electron microscopy, X-ray diffraction, X-ray microtomography and spectrophotometry with a hydroxyproline assay. Scanning electron microscopy showed that dentine collagen was exposed in group W, but not in groups SF and SDF, while clusters of granular spherical grains were formed in groups SF and SDF. The mean lesion depths (±standard deviation) of groups SF, SDF and W were 128 ± 19, 135 ± 24 and 258 ± 53 μm, respectively (SF, SDF < W; P < 0.001). The X-ray diffraction analysis indicated that silver chloride was formed in groups SF and SDF. The concentration of hydroxyproline released from the dentine matrix was significantly lower in groups SF and SDF than in group W (P < 0.05). The results of this in vitro study indicate that the use of silver nitrate solution and sodium fluoride varnish is effective in inhibiting dentine demineralisation and dentine collagen degradation. © 2017 FDI World Dental Federation.

  16. Method for the recovery of uranium values from uranium tetrafluoride

    DOEpatents

    Kreuzmann, Alvin B.

    1983-01-01

    The invention is a novel method for the recovery of uranium from dry, particulate uranium tetrafluoride. In one aspect, the invention comprises reacting particulate uranium tetrafluoride and calcium oxide in the presence of gaseous oxygen to effect formation of the corresponding alkaline earth metal uranate and alkaline earth metal fluoride. The product uranate is highly soluble in various acidic solutions wherein the product fluoride is virtually insoluble therein. The product mixture of uranate and alkaline earth metal fluoride is contacted with a suitable acid to provide a uranium-containing solution, from which the uranium is recovered. The invention can achieve quantitative recovery of uranium in highly pure form.

  17. Method for the recovery of uranium values from uranium tetrafluoride

    DOEpatents

    Kreuzmann, A.B.

    1982-10-27

    The invention is a novel method for the recovery of uranium from dry, particulate uranium tetrafluoride. In one aspect, the invention comprises reacting particulate uranium tetrafluoride and calcium oxide in the presence of gaseous oxygen to effect formation of the corresponding alkaline earth metal uranate and alkaline earth metal fluoride. The product uranate is highly soluble in various acidic solutions whereas the product fluoride is virtually insoluble therein. The product mixture of uranate and alkaline earth metal fluoride is contacted with a suitable acid to provide a uranium-containing solution, from which the uranium is recovered. The invention can achieve quantitative recovery of uranium in highly pure form.

  18. Topical Silver Diamine Fluoride for Dental Caries Arrest in Preschool Children: A Randomized Controlled Trial and Microbiological Analysis of Caries Associated Microbes and Resistance Gene Expression.

    PubMed

    Milgrom, Peter; Horst, Jeremy A; Ludwig, Sharity; Rothen, Marilynn; Chaffee, Benjamin W; Lyalina, Svetlana; Pollard, Katherine S; DeRisi, Joseph L; Mancl, Lloyd

    2017-08-30

    The Stopping Cavities Trial investigated effectiveness and safety of 38% silver diamine fluoride in arresting caries lesions. The study was a double-blind randomized placebo-controlled superiority trial with 2 parallel groups. The sites were Oregon preschools. Sixty-six preschool children with ≥1 lesion were enrolled. Silver diamine fluoride (38%) or placebo (blue-tinted water), applied topically to the lesion. The primary endpoint was caries arrest (lesion inactivity, Nyvad criteria) 14-21days post intervention. Dental plaque was collected from all children, and microbial composition was assessed by RNA sequencing from 2 lesions and 1 unaffected surface before treatment and at follow-up for 3 children from each group. Average proportion of arrested caries lesions in the silver diamine fluoride group was higher (0.72; 95% CI; 0.55, 0.84) than in the placebo group (0.05; 95% CI; 0.00, 0.16). Confirmatory analysis using generalized estimating equation log-linear regression, based on the number of arrested lesions and accounting for the number of treated surfaces and length of follow-up, indicates the risk of arrested caries was significantly higher in the treatment group (relative risk, 17.3; 95% CI: 4.3 to 69.4). No harms were observed. RNA sequencing analysis identified no consistent changes in relative abundance of caries-associated microbes, nor emergence of antibiotic or metal resistance gene expression. Topical 38% silver diamine fluoride is effective and safe in arresting cavities in preschool children. The treatment is applicable to primary care practice and may reduce the burden of untreated tooth decay in the population. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  19. Process for converting magnesium fluoride to calcium fluoride

    DOEpatents

    Kreuzmann, A.B.; Palmer, D.A.

    1984-12-21

    This invention is a process for the conversion of magnesium fluoride to calcium fluoride whereby magnesium fluoride is decomposed by heating in the presence of calcium carbonate, calcium oxide or calcium hydroxide. Magnesium fluoride is a by-product of the reduction of uranium tetrafluoride to form uranium metal and has no known commercial use, thus its production creates a significant storage problem. The advantage of this invention is that the quality of calcium fluoride produced is sufficient to be used in the industrial manufacture of anhydrous hydrogen fluoride, steel mill flux or ceramic applications.

  20. The uranium-bearing nickel-cobalt-native silver deposits in the Black Hawk district, Grant County, New Mexico

    USGS Publications Warehouse

    Gillerman, Elliot; Whitebread, Donald H.

    1953-01-01

    The Black Hawk (Bullard Peak) district, Grant County, N. Mex., is 21 miles by road west of Silver City. From 1881 to 1893 more than $1,000,000.00 of high-grade silver ore is reported to have been shipped from the district. Since 1893 there has been no mining in the district except during a short period in 1917 when the Black Hawk mine was rehabilitated. Pre-Cambrian quartz diorite gneiss, which contains inclusions of quartzite, schist, monzonite, and quartz monzonite, is the most widespread rock in the district. The quartz diorite gneiss is intruded by many pre-Cambrian and younger rocks, including diorite granite, diabase, monzonite porphyry and andesite and is overlain by the Upper Cretaceous Beartooth quartzite. The monzonite porphyry, probably of late Cretaceous or early Tertiary age, forms a small stock along the northwestern edge of the district and numerous dikes and irregular masses throughout the district. The ore deposits are in fissure veins that contain silver, cobalt, and uranium. The ore minerals, which include native silver, niccolite, millerite, skutterudite, nickel skutterudite, bismuthinite, pitchblende, and sphalerite, are in a carbonate gangue in narrow, persistent veins, most of which trend northeasterly. Pitchblende has been identified in the Black Hawk and the Alhabra deposits and unidentified radioactive minerals were found at five other localities. The deposits that contain the radioactive minerals constitude a belt 600 to 1,500 feet wide that trends about N. 45° E., and is approximately parallel to the southeastern boundary of the monzonite porphyry stock. All the major ore deposits are in the quartz diorite gneiss in close proximity to the monzonite porphyry. The ore deposits are similar to the deposits at Great Bear Lake, Canada, and Joachimstahl, Czechoslovakia.

  1. The chemistry of the uranium oxyfluorides

    SciTech Connect

    Manuta, D.M.

    1995-12-31

    Uranuim oxyfluorides result from the hydrolysis of uranium hexafluoride. The ratio of water to uranium hexafluoride determines the uranium oxyfluoride product formed. Uranyl fluoride is the most important of the compounds formed.

  2. Randomized clinical trial on arresting dental root caries through silver diammine fluoride applications in community-dwelling elders.

    PubMed

    Li, R; Lo, E C M; Liu, B Y; Wong, M C M; Chu, C H

    2016-08-01

    To investigate the effectiveness of silver diammine fluoride (SDF) solution application in arresting dental root caries and to assess the color of arrested caries lesions. This study was conducted in elderly centers in Hong Kong. A total of 83 elders with 157 root surfaces with active caries lesion were randomly allocated into 3 groups: Gp1 (placebo control)-annual application of soda water; Gp2-annual application of SDF solution; Gp3-annual application of SDF solution immediately followed by potassium iodide (KI) solution. Color of the arrested root caries lesion was assessed with reference to PANTONE color plates and classified into one of the followings: yellow (7401U); light brown (1245U); dark brown (4635U); and black (Black U). Status of root surfaces was assessed every 6 months by the same independent examiner. After 30 months, 100 (64%) of the included root caries lesions were reviewed. The arrest rates of root caries were 45%, 90%, and 93% in Gp1 (control), Gp2 (SDF) and Gp3 (SDF/KI), respectively (χ(2) test, p<0.001). Pairwise comparisons showed elders in the control group had a lower proportion of the active root caries changed to arrested (p<0.001) and the proportions of root caries being arrested in the SDF and SDF/KI groups were not significantly different (p>0.05). The distributions of arrested caries lesions by color were not significantly different between the SDF and SDF/KI groups (χ(2) test, p>0.05). Application of SDF solution, with or without application of KI afterwards, is effective in arresting root caries among elders in a water fluoridated area. In the long term, blackening of arrested root caries is not reduced by immediate application of KI after the application of SDF. In a water fluoridated area, annual application of SDF solution or SDF/KI solution can arrest dental root caries in elders. In the long term, application of KI does not reduce the blackening of arrested caries lesions caused by SDF. Copyright © 2016 The Authors

  3. Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes.

    PubMed

    De Gusseme, Bart; Hennebel, Tom; Christiaens, Eline; Saveyn, Hans; Verbeken, Kim; Fitts, Jeffrey P; Boon, Nico; Verstraete, Willy

    2011-02-01

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag(0)) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag(0) particles, preventing aggregation during encapsulation. In this study, bio-Ag(0) was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag(0) and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag(+) from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag(0)(powder) m(-2) in a submerged plate membrane reactor operated at a flux of 3.1 L m(-2) h(-1). Upon startup, the silver concentration in the effluent initially increased to 271 μg L(-1) but after filtration of 31 L m(-2), the concentration approached the drinking water limit ( = 100 μg L(-1)). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m(-2) h(-1), showing the potential of this membrane technology for water disinfection on small scale.

  4. Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes

    SciTech Connect

    Gusseme, B.D.; Fitts, J.; Hennebel, T.; Christiaens, E.; Saveyn, H.; Verbeken, K.; Boon, N.; Verstraete, W.

    2011-03-01

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sub powder}{sup 0} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {micro}g L{sup -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {micro}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale. In biogenic silver, silver nanoparticles are attached to a bacterial carrier matrix. Bio-Ag{sup 0} was successfully immobilized in PVDF membranes using immersion-precipitation. The antiviral activity of this material was demonstrated in a plate membrane reactor. The antimicrobial mechanism was most probably related to the slow release of Ag{sup +} ions. The membranes can be applied for treatment of limited volumes of contaminated water.

  5. Structural, Elastic, Electronic and Optical Properties of LaOAgS-Type Silver Fluoride Chalcogenides: First-Principles Study

    NASA Astrophysics Data System (ADS)

    Boudiaf, K.; Bouhemadou, A.; Boudrifa, O.; Haddadi, K.; Saoud, F. Saad; Khenata, R.; Al-Douri, Y.; Bin-Omran, S.; Ghebouli, M. A.

    2017-07-01

    First-principles density functional calculations were performed to investigate the structural parameters, elastic moduli and related properties, electronic band structure and optical properties of three LaOAgS-type barium silver fluoride chalcogenides BaAg ChF ( Ch denotes the chalcogenides S, Se and Te). The calculated structural parameters are in good accordance with the existing experimental data. The single-crystal and polycrystal elastic moduli were determined via the strain-stress technique. The investigated compounds show a strong anisotropic behaviour of the structural and elastic parameters. The calculated electronic band structure using the Tran-Blaha modified Becke-Johnson potential reveals that the three considered systems are large direct band gap semiconductors. The assignments of the energy band electronic states and chemical bonding character were accomplished with the help of the l-decomposed atomic densities of states diagrams. Frequency-dependent polarized optical functions were computed for an energy range from 0 eV to 30 eV. The microscopic origin of the electronic states that is responsible for the optical spectra structures were determined. The optical spectra exhibit a considerable anisotropy. Several trends in the variation of the considered physical properties with the atomic number Z of the chalcogenide Ch element in the BaAg ChF series are observed.

  6. Effects of silver diamine fluoride on dentine carious lesions induced by Streptococcus mutans and Actinomyces naeslundii biofilms.

    PubMed

    Chu, Chun Hung; Mei, Lei; Seneviratne, Chaminda Jayampath; Lo, Edward Chin Man

    2012-01-01

    BACKGROUND. Silver diamine fluoride (SDF) has been shown to be a successful treatment for arresting caries. However, the mechanism of SDF is to be elucidated. AIM. To characterize the effects of SDF on dentine carious induced by Streptococcus mutans and Actinomyces naeslundii. DESIGN.  Thirty-two artificially demineralized human dentine blocks were inoculated: 16 with S. mutans and 16 with A. naeslundii. Either SDF or water was applied to eight blocks in each group. Biofilm morphology, microbial kinetics and viability were evaluated by scanning electron microscopy, colony forming units, and confocal microscopy. The crosssection of the dentine carious lesions were assessed by microhardness testing, scanning electron microscopy with energy-dispersive x-ray spectroscopy and Fourier transform infrared spectroscopy. RESULTS. Biofilm counts were reduced in SDF group than control (P < 0.01). Surfaces of carious lesions were harder after SDF application than after water application (P < 0.05), in S. mutans group, Ca and P weight percentage after SDF application than after water application (P < 0.05). Lesions showed a significantly reduced level of matrix to phosphate after SDF treatment (P < 0.05). CONCLUSION. Present study showed that SDF posses an anti-microbial activity against cariogenic biofilm of S. mutans or A. naeslundii formed on dentine surfaces. SDF slowed down demineralization of dentine. This dual activity could be the reason behind clinical success of SDF. © 2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.

  7. Virus Disinfection in Water by Biogenic Silver Immobilized in Polyvinylidene Fluoride Membranes

    SciTech Connect

    B De Gusseme; T Hennebel; E Christiaens; H Saveyn; K Verbeken; J Fitts; N Boon; W Vertraete

    2011-12-31

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sup 0}{sub powder} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {mu}g L{sub -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {mu}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale.

  8. METHOD OF PRODUCING URANIUM METAL BY ELECTROLYSIS

    DOEpatents

    Piper, R.D.

    1962-09-01

    A process is given for making uranium metal from oxidic material by electrolytic deposition on the cathode. The oxidic material admixed with two moles of carbon per one mole of uranium dioxide forms the anode, and the electrolyte is a mixture of from 40 to 75% of calcium fluoride or barium fluoride, 15 to 45% of uranium tetrafluoride, and from 10 to 20% of lithium fluoride or magnesium fluoride; the temperature of the electrolyte is between 1150 and 1175 deg C. (AEC)

  9. Silver- and fluoride-containing mesoporous bioactive glasses versus commonly used antibiotics: Activity against multidrug-resistant bacterial strains isolated from patients with burns.

    PubMed

    Gholipourmalekabadi, M; Sameni, M; Hashemi, A; Zamani, F; Rostami, A; Mozafari, M

    2016-02-01

    The wound healing process is frequently associated with a number of major clinical challenges, due to the failure of commonly used antibiotics as a remedy for wounds. There have always been fascinating questions about the novel applications of bioactive glasses (BGs) and it is expected that in the next few years these types of materials may play an important role in many aspects of soft tissue regeneration. This research focuses on the feasibility of using silver- and fluoride-containing BGs against multidrug-resistant bacterial strains isolated from patients with burns. According to the results obtained, fluoride did not exhibit antibacterial activity against the tested bacteria, while both 1% and 2% silver-containing BGs inhibited the bacterial growth. It is an important finding that 1% silver-containing BGs showed a potential antibacterial activity without any toxicity against fibroblasts, suggesting that this class of BGs could play a key role in the prevention of infection, reduction of pain, and removal of excessive exudates. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

  10. Prevention of dentine caries using silver diamine fluoride application followed by Er:YAG laser irradiation: an in vitro study.

    PubMed

    Mei, May L; Ito, Leticia; Chu, C H; Lo, Edward C M; Zhang, C F

    2014-11-01

    To evaluate the preventive effect of Er:YAG laser (EYL) irradiation followed by silver diamine fluoride (SDF) application on dentine with cariogenic biofilm challenge. Twenty-four dentine slices were prepared from extracted sound human third molars. Each slice was cut into four parts for SDF application, followed by EYL irradiation (group SL), SDF application (group S), EYL irradiation (group L) and water (group W). The specimens were subjected to cariogenic biofilm challenge for 12 h, followed by immersion in a buffered remineralising solution containing calcium chloride and sodium hypophosphate for 12 h at 37 °C. Surface morphological changes in the specimens were examined using scanning electronic microscopy. Elemental analysis was performed using energy-dispersive X-ray spectrometry. Micro-mechanical properties were investigated by nano-indentation. The specimen surfaces of groups SL and L showed laser melting contours with narrowed dentinal orifices. Group S showed a partial tubular occlusion. A porous surface was observed in group W, indicating demineralisation. The mean (SD) fluoride weight percentages were 3.93 (0.91), 3.10 (0.61), 0.17 (0.09) and 0.32 (0.07) in groups SL, S, L and W, respectively, (p < 0.001; SL, S > L, W). The mean (SD) micro-hardness values in GPa were 1.84 (0.22), 0.49 (0.13), 0.41 (0.11) and 0.30 (0.06) in groups SL, S, L and W, respectively, (p < 0.001; SL > S > L, W). The mean (SD) elastic moduli in GPa were 75.1 (7.2), 20.0 (1.3), 24.3 (5.2) and 20.2 (2.8) in groups SL, S, L and W, respectively, (p < 0.001; SL > S, L, W). SDF application followed by EYL irradiation on a dentine surface increased its resistance to cariogenic biofilm challenge.

  11. Prediction of Extremely Strong Antiferromagnetic Superexchange in Silver(II) Fluorides: Challenging the Oxocuprates(II).

    PubMed

    Kurzydłowski, Dominik; Grochala, Wojciech

    2017-08-14

    Strong magnetic coupling between the spins of unpaired electrons is an essential ingredient of many fascinating physical phenomena. Here we report calculations using the hybrid HSE06 functional of magnetic superexchange constants, J, for a series of low-dimensional Cu(II) and Ag(II) binary and ternary systems with fluoride and oxide ligands. The calculations correctly reproduce the sign and size of the magnetic superexchange constants for prototypical antiferromagnetic (AFM) 1D (J1D ) and 2D (J2D ) systems, while overestimating the absolute values of J by about 11 %. We find that [AgF][BF4 ], a quasi-1D system with linear infinite [Ag(II) F(+) ] chains, is predicted to exhibit an unprecedented strong AFM superexchange via one atom (F), with J1D about -300 meV. Compression of [AgF][BF4 ] to 10 GPa should lead to a further increase in AFM interactions with J1D reaching -360 meV at 10 GPa. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Caries arresting effect of silver diamine fluoride on dentine carious lesion with S. mutans and L. acidophilus dual-species cariogenic biofilm

    PubMed Central

    Mei, May L.; Low, Kan H.; Che, Ching M.; Lo, Edward CM.

    2013-01-01

    Objectives: This in vitro study investigated the effects of silver diamine fluoride (SDF) on dentine carious lesion with cariogenic biofilm. Study Design: Thirty human dentine blocks were inoculated with Streptococcus mutans and Lactobacillus acidophilus dual-species biofilm to create carious lesion. They were equally divided into test and control group to receive topical application of SDF and water. After incubation anaerobically using micro-well plate at 37oC for 7 days, the biofilms were evaluated for kinetics, morphology and viability by colony forming units (CFU), scanning electron microscopy (SEM), and confocal microscopy (CLSM), respectively. The carious lesion underwent crystal characteristics analysis, evaluation of the changes in chemical structure and density of collagen fibrils using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and immune-labeling. Results: The log CFU of S. mutans and L. acidophilus in the test group was significantly lower than control group. SEM and CLSM showed confluent biofilm in control group, but not in test group. XRD showed the loss of crystallinity of dentine due to the dissolution of hydroxyapatite crystal structure in test group was less than control group. FTIR showed that log [Amide I: HPO42-] for test vs. control group was 0.31±0.10 vs. 0.57±0.13 (p<0.05). The gold-labeling density in test vs. control group was 8.54±2.44/µm2 vs. 12.91±4.24/µm2 (p=0.04). Conclusions: SDF had antimicrobial activity against the cariogenic biofilms and reduced demineralization of dentine. Key words:Caries, caries arrest, dentine, silver, silver diamine fluoride, fluoride, biofilm,cariogenic. PMID:23722131

  13. Pharmacological and toxicological effects of co-exposure of human gingival fibroblasts to silver nanoparticles and sodium fluoride

    PubMed Central

    Inkielewicz-Stepniak, Iwona; Santos-Martinez, Maria Jose; Medina, Carlos; Radomski, Marek W

    2014-01-01

    Background Silver nanoparticles (AgNPs) and fluoride (F) are pharmacological agents widely used in oral medicine and dental practice due to their anti-microbial/anti-cavity properties. However, risks associated with the co-exposure of local cells and tissues to these xenobiotics are not clear. Therefore, we have evaluated the effects of AgNPs and F co-exposure on human gingival fibroblast cells. Methods Human gingival fibroblast cells (CRL-2014) were exposed to AgNPs and/or F at different concentrations for up to 24 hours. Cellular uptake of AgNPs was examined by transmission electron microscopy. Downstream inflammatory effects and oxidative stress were measured by real-time quantitative polymerase chain reaction (PCR) and reactive oxygen species (ROS) generation. Cytotoxicity and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and real-time quantitative PCR and flow cytometry, respectively. Finally, the involvement of mitogen-activated protein kinases (MAPK) was studied using Western blot. Results We found that AgNPs penetrated the cell membrane and localized inside the mitochondria. Co-incubation experiments resulted in increased oxidative stress, inflammation, and apoptosis. In addition, we found that co-exposure to both xenobiotics phosphorylated MAPK, particularly p42/44 MAPK. Conclusion A combined exposure of human fibroblasts to AgNPs and F results in increased cellular damage. Further studies are needed in order to evaluate pharmacological and potentially toxicological effects of AgNPs and F on oral health. PMID:24729703

  14. Synthesis, structure, and reactivity of high oxidation state silver fluorides and related compounds

    SciTech Connect

    Lucier, George Michael

    1995-05-01

    This thesis has been largely concerned with defining the oxidizing power of Ag(III) and Ag(II) in anhydrous hydrogen fluoride (aHF) solution. Emphasis was on cationic species, since in a cation the electronegativity of a given oxidation state is greatest. Cationic Ag(III) solv has a short half life at ordinary temperatures, oxidizing the solvent to elemental fluorine with formation of Ag(II). Salts of such a cation have not yet been preparable, but solutions which must contain such a species have proved to be effective and powerful oxidizers. In presence of PtF6-, RuF6-, or RhF6-, Ag(III) solv effectively oxidizes the anions to release the neutral hexafluorides. Such reactivity ranks cationic Ag(III) as the most powerfully oxidizing chemical agent known as far. Unlike its trivalent relative Ag (II) solv is thermodynamically stable in acid aHF. Nevertheless, it oxidizes IrF6- to IrF6 at room temperature, placing its oxidizing potential not more than 2 eV below that of cationic Ag(III). Range of Ag2+ (MF6-2 salts attainable in aHF has been explored. An anion must be stable with respect to electron loss to Ag2+. The anion must also be a poor F- donor; otherwise, either AgF+ salts or AgF2 are generated.

  15. Use of silver diamine fluoride for the maintenance of dental prostheses in a high caries-risk patient: A medical management approach.

    PubMed

    Giusti, Lola; Steinborn, Cathrine; Steinborn, Maya

    2017-09-06

    A technique for using silver diamine fluoride (SDF) as part of a regimen to help maintain dental prostheses in a patient with scleroderma and at high risk of caries is presented. Medically compromised, xerostomic, or elderly patients generally face greater risk of caries and specifically with prosthetic retainer teeth. SDF is a minimally invasive solution to this problem. A technique is described for using SDF to arrest and prevent new caries with the goal of maintaining fixed and removable prostheses and supporting teeth in a cost-effective manner. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Toxic influence of silver and uranium salts on activated sludge of wastewater treatment plants and synthetic activated sludge associates modeled on its pure cultures.

    PubMed

    Tyupa, Dmitry V; Kalenov, Sergei V; Skladnev, Dmitry A; Khokhlachev, Nikolay S; Baurina, Marina M; Kuznetsov, Alexander Ye

    2015-01-01

    Toxic impact of silver and uranium salts on activated sludge of wastewater treatment facilities has been studied. Some dominating cultures (an active nitrogen fixer Agrobacterium tumifaciens (A.t) and micromyces such as Fusarium nivale, Fusarium oxysporum, and Penicillium glabrum) have been isolated and identified as a result of selection of the activated sludge microorganisms being steadiest under stressful conditions. For these cultures, the lethal doses of silver amounted 1, 600, 50, and 300 µg/l and the lethal doses of uranium were 120, 1,500, 1,000, and 1,000 mg/l, respectively. A.tumifaciens is shown to be more sensitive to heavy metals than micromyces. Synthetic granular activated sludge was formed on the basis of three cultures of the isolated micromyces steadiest against stress. Its granules were much more resistant to silver than the whole native activated sludge was. The concentration of silver causing 50 % inhibition of synthetic granular activated sludge growth reached 160-170 μg/l as far as for the native activated sludge it came only to 100-110 μg/l.

  17. Method for converting uranium oxides to uranium metal

    DOEpatents

    Duerksen, Walter K.

    1988-01-01

    A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

  18. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    DOEpatents

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

    1960-01-01

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

  19. ELECTROLYTIC PRODUCTION OF URANIUM TETRAFLUORIDE

    DOEpatents

    Lofthouse, E.

    1954-08-31

    This patent relates to electrolytic methods for the production of uranium tetrafluoride. According to the present invention a process for the production of uranium tetrafluoride comprises submitting to electrolysis an aqueous solution of uranyl fluoride containing free hydrofluoric acid. Advantageously the aqueous solution of uranyl fluoride is obtained by dissolving uranium hexafluoride in water. On electrolysis, the uranyl ions are reduced to uranous tons at the cathode and immediately combine with the fluoride ions in solution to form the insoluble uranium tetrafluoride which is precipitated.

  20. New proposal of silver diamine fluoride use in arresting approximal caries: study protocol for a randomized controlled trial.

    PubMed

    Mattos-Silveira, Juliana; Floriano, Isabela; Ferreira, Fernanda R; Viganó, Maria E F; Frizzo, M A; Reyes, Alessandra; Novaes, Tatiane F; Moriyama, Caroline M; Raggio, Daniela P; Imparato, José C P; Mendes, Fausto M; Braga, Mariana M

    2014-11-19

    Approximal surfaces are a challenge to caries lesions control. Silver diamine fluoride (SDF) is a simple,low-cost and promisor intervention for arresting caries lesions, but it has never been tested on approximal surfaces. Our aim is to evaluate the efficacy and cost-efficacy of SDF in arresting initial lesions compared to resin infiltration and exclusively flossing (control group). Our second aim is to assess discomfort and satisfaction regarding interventions. This is a randomized clinical trial, double-blinded, placebo-controlled study. Children/adolescents presenting at least one approximal initial caries lesion in primary molars/permanent premolars and molars will be included. Surfaces with advanced dentine lesions identified by radiography and participants who refuse to participate or present negative behaviors will be excluded. A minimum sample size of 504 surfaces will be required for each subgroup. Individuals will be randomly allocated in three groups of interventions: SDF, resin infiltration, and control group. Depending on the allocation, the patients will receive the active treatment and respective placebo therapies. All patients will be oriented to daily flossing the included surfaces. Our primary outcome will be caries progression by clinical and radiographic examinations. Appointments will be timed and costs of materials will be considered to calculate cost-efficacy. Patient discomfort will be assessed after interventions. Parent and patient satisfaction with the treatment will be collected after treatment and in the last follow-up visit. Individuals will be assessed at 1 and 3 months after treatment to evaluate dental biofilm and at 6, 12, and 24 months to assess caries progression by visual examination and/or radiography. Multilevel analyses will be used to verify if the type of treatment influenced on the tested outcomes. Costs will be compared and analyses of cost-efficacy will be performed. Poisson analysis will test the association between

  1. Uranium hexafluoride liquid thermal expansion, elusive eutectic with hydrogen fluoride, and very first production using chlorine trifluoride

    SciTech Connect

    Rutledge, G.P.

    1991-12-31

    Three unusual incidents and case histories involving uranium hexafluoride in the enrichment facilities of the USA in the late 1940`s and early 1950`s are presented. The history of the measurements of the thermal expansion of liquids containing fluorine atoms within the molecule is reviewed with special emphasis upon uranium hexafluoride. A comparison is made between fluorinated esters, fluorocarbons, and uranium hexafluoride. The quantitative relationship between the thermal expansion coefficient, a, of liquids and the critical temperature, T{sub c} is presented. Uranium hexafluoride has an a that is very high in a temperature range that is used by laboratory and production workers - much higher than any other liquid measured. This physical property of UF{sub 6} has resulted in accidents involving filling the UF{sub 6} containers too full and then heating with a resulting rupture of the container. Such an incident at a uranium gaseous diffusion plant is presented. Production workers seldom {open_quotes}see{close_quotes} uranium hexafluoride. The movement of UF{sub 6} from one container to another is usually trailed by weight, not sight. Even laboratory scientists seldom {open_quotes}see{close_quotes} solid or liquid UF{sub 6} and this can be a problem at times. This inability to {open_quotes}see{close_quotes} the UF{sub 6}-HF mixtures in the 61.2{degrees}C to 101{degrees}C temperature range caused a delay in the understanding of the phase diagram of UF{sub 6}-HF which has a liquid - liquid immiscible region that made the eutectic composition somewhat elusive. Transparent fluorothene tubes solved the problem both for the UF{sub 6}-HF phase diagram as well as the UF{sub 6}-HF-CIF{sub 3} phase diagram with a miscibility gap starting at 53{degrees}C. The historical background leading to the first use of CIF{sub 3} to produce UF{sub 6} in both the laboratory and plant at K-25 is presented.

  2. PRODUCTION OF URANIUM

    DOEpatents

    Spedding, F.H.; Wilhelm, H.A.; Keller, W.H.

    1958-04-15

    The production of uranium metal by the reduction of uranium tetrafluoride is described. Massive uranium metal of high purily is produced by reacting uranium tetrafluoride with 2 to 20% stoichiometric excess of magnesium at a temperature sufficient to promote the reaction and then mantaining the reaction mass in a sealed vessel at temperature in the range of 1150 to 2000 d C, under a superatomospheric pressure of magnesium for a period of time sufficient 10 allow separation of liquid uranium and liquid magnesium fluoride into separate layers.

  3. Remineralizing efficacy of silver diamine fluoride and glass ionomer type VII for their proposed use as indirect pulp capping materials – Part II (A clinical study)

    PubMed Central

    Sinha, N; Gupta, A; Logani, A; Shah, N

    2011-01-01

    Aim: To evaluate in vivo the remineralizing efficacy of silver diamine fluoride (SDF), glass ionomer Type VII (GC VII) and calcium hydroxide (Dycal). Materials and Methods: 60 subjects in the age group of 18-35 years, matching the inclusion criteria and having deep carious lesions in the permanent first and second molars were selected. The teeth were aseptically opened under rubber dam and after gross caries removal, approximately 0.4mg of soft discolored dentin was removed with a sharp spoon excavator from the mesial or distal aspect of the cavity. The test material was randomly selected and applied in a thickness of 1.5-2mm and the cavity sealed with cavit. The patients were followed up at regular intervals with radiographic evaluation at 12 weeks. At 3 months the temporary restoration was removed and dentin samples were collected from the other half of the cavity which was left in the first appointment. Atomic absorption spectrophotometry, Colorimetric test using UV-vis spectrometer and potentiometric titration were used for determining calcium, phosphorous and fluoride respectively. Results: Almost equivalent rise in the percentage of calcium level was seen in GC VII and Ca(OH)2 groups, followed by SDF group. Highest percentage rise in phosphate ions was seen in GC VII group followed by SDF group and Ca(OH)2 group. Highest percentage of fluoride rise was seen in GC VII group followed by SDF group and Ca(OH)2 group. Conclusions: The results indicated that both GC VII and SDF can be potential indirect pulp capping materials. PMID:22025824

  4. Remineralizing efficacy of silver diamine fluoride and glass ionomer type VII for their proposed use as indirect pulp capping materials - Part II (A clinical study).

    PubMed

    Sinha, N; Gupta, A; Logani, A; Shah, N

    2011-07-01

    To evaluate in vivo the remineralizing efficacy of silver diamine fluoride (SDF), glass ionomer Type VII (GC VII) and calcium hydroxide (Dycal). 60 subjects in the age group of 18-35 years, matching the inclusion criteria and having deep carious lesions in the permanent first and second molars were selected. The teeth were aseptically opened under rubber dam and after gross caries removal, approximately 0.4mg of soft discolored dentin was removed with a sharp spoon excavator from the mesial or distal aspect of the cavity. The test material was randomly selected and applied in a thickness of 1.5-2mm and the cavity sealed with cavit. The patients were followed up at regular intervals with radiographic evaluation at 12 weeks. At 3 months the temporary restoration was removed and dentin samples were collected from the other half of the cavity which was left in the first appointment. Atomic absorption spectrophotometry, Colorimetric test using UV-vis spectrometer and potentiometric titration were used for determining calcium, phosphorous and fluoride respectively. Almost equivalent rise in the percentage of calcium level was seen in GC VII and Ca(OH)(2) groups, followed by SDF group. Highest percentage rise in phosphate ions was seen in GC VII group followed by SDF group and Ca(OH)(2) group. Highest percentage of fluoride rise was seen in GC VII group followed by SDF group and Ca(OH)(2) group. The results indicated that both GC VII and SDF can be potential indirect pulp capping materials.

  5. Caries preventive efficacy of silver diammine fluoride (SDF) and ART sealants in a school-based daily fluoride toothbrushing program in the Philippines.

    PubMed

    Monse, Bella; Heinrich-Weltzien, Roswitha; Mulder, Jan; Holmgren, Christopher; van Palenstein Helderman, Wim H

    2012-11-21

    Occlusal surfaces of erupting and newly erupted permanent molars are particularly susceptible to caries.The objective of the study was to assess and compare the effect of a single application of 38% SDF with ART sealants and no treatment in preventing dentinal (D3) caries lesions on occlusal surfaces of permanent first molars of school children who participated in a daily school-based toothbrushing program with fluoride toothpaste. The prospective community clinical trial in the Philippines was conducted over a period of 18 months and included 704 six- to eight-year-old school children in eight public elementary schools with a daily school-based fluoride toothpaste brushing program. Children were randomly assigned for SDF application or ART sealant treatment. Children from two of the eight schools did not receive SDF or ART sealant treatment and served as controls. SDF or ART sealant treatment was applied on sound occlusal surfaces of permanent first molars. Surfaces that were originally defined as sound at baseline but which changed to dentinal (D3) caries lesions were defined as surfaces with new caries (caries increment). Non-compliance to the daily toothbrushing program in three schools offered the opportunity to analyze the caries preventive effect of SDF and sealants separately in fluoride toothpaste brushing and in non-toothbrushing children. In the brushing group, caries increment in the SDF treatment group was comparable with the non-treatment group but caries increment in the sealant group was lower than in the non-treatment group with a statistically significant lower hazard ratio of 0.12 (0.02-0.61). In the non-brushing group, caries increment in the SDF treatment group and the sealant group was lower than the non-treatment group but the hazard ratio was only statistically significant for the sealant group (HR 0.33; 0.20-0.54). Caries increment was lower in toothbrushing children than in non-toothbrushing children. Hazard ratios reached statistical

  6. Caries preventive efficacy of silver diammine fluoride (SDF) and ART sealants in a school-based daily fluoride toothbrushing program in the Philippines

    PubMed Central

    2012-01-01

    Background Occlusal surfaces of erupting and newly erupted permanent molars are particularly susceptible to caries. The objective of the study was to assess and compare the effect of a single application of 38% SDF with ART sealants and no treatment in preventing dentinal (D3) caries lesions on occlusal surfaces of permanent first molars of school children who participated in a daily school-based toothbrushing program with fluoride toothpaste. Methods The prospective community clinical trial in the Philippines was conducted over a period of 18 months and included 704 six- to eight-year-old school children in eight public elementary schools with a daily school-based fluoride toothpaste brushing program. Children were randomly assigned for SDF application or ART sealant treatment. Children from two of the eight schools did not receive SDF or ART sealant treatment and served as controls. SDF or ART sealant treatment was applied on sound occlusal surfaces of permanent first molars. Surfaces that were originally defined as sound at baseline but which changed to dentinal (D3) caries lesions were defined as surfaces with new caries (caries increment). Non-compliance to the daily toothbrushing program in three schools offered the opportunity to analyze the caries preventive effect of SDF and sealants separately in fluoride toothpaste brushing and in non-toothbrushing children. Results In the brushing group, caries increment in the SDF treatment group was comparable with the non-treatment group but caries increment in the sealant group was lower than in the non-treatment group with a statistically significant lower hazard ratio of 0.12 (0.02-0.61). In the non-brushing group, caries increment in the SDF treatment group and the sealant group was lower than the non-treatment group but the hazard ratio was only statistically significant for the sealant group (HR 0.33; 0.20-0.54). Caries increment was lower in toothbrushing children than in non-toothbrushing children. Hazard

  7. Silver

    Integrated Risk Information System (IRIS)

    Silver ; CASRN 7440 - 22 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  8. Maps showing distribution of pH, copper, zinc, fluoride, uranium, molybdenum, arsenic, and sulfate in water, Richfield 1 degree by 2 degrees Quadrangle, Utah

    USGS Publications Warehouse

    McHugh, J.B.; Miller, W.R.; Ficklin, W.H.

    1984-01-01

    These maps show the regional distribution of copper, zinc, arsenic, molybdenum, uranium, fluoride, sulfate, and pH in surface and ground water from the Richfield 1° x 2° quadrangle. This study supplements (Miller and others, 1984a-j) the regional drainage geochemical study done for the Richfield quadrangle under the U.S. Geological Survey’s Conterminuous United States Mineral Assessment Program (CUSMAP). Regional sampling was designed to define broad geochemical patterns and trends which can be used, along with geologic and geophysical data, to assess the mineral resource potential of the Richfield quadrangle. Analytical data used in compiling this report were published previously (McHugh and others, 1981). The Richfield quadrangle in west-central Utah covers the eastern part of the Pioche-Marysvale igneous and mineral belt that extends from the vicinity of Pioche in southeastern Nevada, east-northeastward for 250 km into central Utah. The western two-thirds of the Richfield quadrangle is in the Basin and Range Province, and the eastern third in the High Plateaus of Utah subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of latest Precambrian and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrane into a series of north-trending fault blocks; the uplifted mountain areas were deeply eroded and the resulting debris deposited in the adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed during igneous activity in the middle and late Cenozoic time.

  9. Variable dimensionality in the uranium fluoride/2-methyl-piperazine system: Synthesis and structures of UFO-5, -6, and -7; Zero-, one-, and two-dimensional materials with unprecedented topologies

    SciTech Connect

    Francis, R.J.; Halasyamani, P.S.; Bee, J.S.; O'Hare, D.

    1999-02-24

    Recently, low temperature (T < 300 C) hydrothermal reactions of inorganic precursors in the presence of organic cations have proven highly productive for the synthesis of novel solid-state materials. Interest in these materials is driven by the astonishingly diverse range of structures produced, as well as by their many potential materials chemistry applications. This report describes the high yield, phase pure hydrothermal syntheses of three new uranium fluoride phases with unprecedented structure types. Through the systematic control of the synthesis conditions the authors have successfully controlled the architecture and dimensionality of the phase formed and selectively synthesized novel zero-, one-, and two-dimensional materials.

  10. PRODUCTION OF URANIUM

    DOEpatents

    Ruehle, A.E.; Stevenson, J.W.

    1957-11-12

    An improved process is described for the magnesium reduction of UF/sub 4/ to produce uranium metal. In the past, there have been undesirable premature reactions between the Mg and the bomb liner or the UF/sub 4/ before the actual ignition of the bomb reaction. Since these premature reactions impair the yield of uranium metal, they have been inhibited by forming a protective film upon the particles of Mg by reacting it with hydrated uranium tetrafluoride, sodium bifluoride, uranyl fluoride, or uranium trioxide. This may be accomplished by adding about 0.5 to 2% of the additive to the bomb charge.

  11. Magnesium fluoride recovery method

    SciTech Connect

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

    1989-10-17

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

  12. Magnesium fluoride recovery method

    SciTech Connect

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

    1989-10-17

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

  13. Fluoridation Basics

    MedlinePlus

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Water Fluoridation Basics Recommend on Facebook Tweet Share Compartir ... because of tooth decay. History of Fluoride in Water In the 1930s, scientists examined the relationship between ...

  14. Occurrence of copper, gold, silver,uranium, tungsten, tin ore deposits in the Late Proterozoic aulacogen mobile melt of southeast China

    SciTech Connect

    Ma, X.H.

    1985-01-01

    In the early period of the late Proterozoic Era (1100 m.y. +/-) an aulacogen mobile belt was formed in the southeast of China. It extends about 1000 km crossing the Yantze Platform and Jiangnan Foldbelt in NNE-NE direction and adjoins the south China geosyncline basement. This belt shows some features of geology and mineralization similar to the Adelaide geosyncline and the Zambia-Zaire Copper-uranium belt. Within the belt, there are about 9000 to 12,000 m polystratotype strata and continuous sediments of the Late Proterozoic Erathem, including alkaline and meta-alkaline volcanic products of 4 epochs of mainly marine facies. A great number of ore-forming elements, such as Cu, U, Pb, Zn, Au, Ag, Fe, Co, Ni, Mn, P, and W, Sn, TR etc., were deposited and enriched in the whole volcano-sedimentary sequency at various times and in various places. A few of them have become syngenetic deposits, but most of them have been transformed into large-scale ore deposits or mineralization fields or areas of copper and gold, lead-zinc and silver, uranium, tungsten, tin, and other metals.

  15. Removal of uranium from aqueous HF solutions

    DOEpatents

    Pulley, Howard; Seltzer, Steven F.

    1980-01-01

    This invention is a simple and effective method for removing uranium from aqueous HF solutions containing trace quantities of the same. The method comprises contacting the solution with particulate calcium fluoride to form uranium-bearing particulates, permitting the particulates to settle, and separting the solution from the settled particulates. The CaF.sub.2 is selected to have a nitrogen surface area in a selected range and is employed in an amount providing a calcium fluoride/uranium weight ratio in a selected range. As applied to dilute HF solutions containing 120 ppm uranium, the method removes at least 92% of the uranium, without introducing contaminants to the product solution.

  16. Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C

    NASA Technical Reports Server (NTRS)

    Wagner, R. C.; Sliney, Harold E.

    1986-01-01

    A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start-stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 748. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-Psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rPm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

  17. Effects of silver and group 2 fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearing to 650 deg C

    NASA Technical Reports Server (NTRS)

    Wagner, R. C.; Sliney, H. E.

    1984-01-01

    A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start/stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 718. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The addtitional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

  18. Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C

    NASA Technical Reports Server (NTRS)

    Wagner, R. C.; Sliney, Harold E.

    1986-01-01

    A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start-stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 748. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-Psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rPm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

  19. Efficacy of silver diamine fluoride for caries reduction in primary teeth and first permanent molars of schoolchildren: 36-month clinical trial.

    PubMed

    Llodra, J C; Rodriguez, A; Ferrer, B; Menardia, V; Ramos, T; Morato, M

    2005-08-01

    We hypothesized that the six-monthly application of silver diamine fluoride (SDF) can arrest the development of caries in the deciduous dentition of six-year-old schoolchildren and prevent caries in their first permanent molars. A prospective controlled clinical trial was conducted on the efficacy of a 38% SDF solution for caries reduction. Four hundred and twenty-five six-year-old children were divided into two groups: One group received SDF solution in primary canines and molars and first permanent molars every 6 mos for 36 mos. The second group served as controls. The 36-month follow-up was completed by 373 children. The mean number of new decayed surfaces appearing in primary teeth during the study was 0.29 in the SDF group vs. 1.43 in controls. The mean of new decayed surfaces in first permanent molars was 0.37 in the SDF group vs. 1.06 in controls. The SDF solution was found to be effective for caries reduction in primary teeth and first permanent molars in schoolchildren.

  20. Arresting rampant dental caries with silver diamine fluoride in a young teenager suffering from chronic oral graft versus host disease post-bone marrow transplantation: a case report

    PubMed Central

    2014-01-01

    Background Rampant caries is an advanced and severe dental disease that affects multiple teeth. This case describes the management of rampant caries in a young teenager suffering from chronic oral graft versus host disease after allogeneic bone marrow transplantation. Case presentation A 14-year-old Chinese boy suffering from β–thalassemia major was referred to the dental clinic for the management of rampant dental caries. An oral examination revealed pale conjunctiva, bruising of lips, and depapillation of tongue indicating an underlying condition of anemia. The poor oral condition due to topical and systemic immunosuppressants was seriously aggravated, and rampant caries developed rapidly, affecting all newly erupted, permanent teeth. The teeth were hypersensitive and halitosis was apparent. Strategies for oral health education and diet modification were given to the patient. Xylitol chewing gum was used to stimulate saliva flow to promote remineralization of teeth. Silver diamine fluoride was topically applied to arrest rampant caries and to relieve pain from hypersensitivity. Carious teeth with pulpal involvement were endodontically treated. Stainless steel crowns were provided on molars to restore chewing function, and polycarbonate crowns were placed on premolars, upper canines and incisors. Conclusion This case report demonstrates success in treating a young teenager with severe rampant dental decay by contemporary caries control and preventive strategy. PMID:24383434

  1. Arresting rampant dental caries with silver diamine fluoride in a young teenager suffering from chronic oral graft versus host disease post-bone marrow transplantation: a case report.

    PubMed

    Chu, Chun-Hung; Lee, Angeline Hui-Cheng; Zheng, Liwu; Mei, May Lei; Chan, Godfrey Chi-Fung

    2014-01-03

    Rampant caries is an advanced and severe dental disease that affects multiple teeth. This case describes the management of rampant caries in a young teenager suffering from chronic oral graft versus host disease after allogeneic bone marrow transplantation. A 14-year-old Chinese boy suffering from β-thalassemia major was referred to the dental clinic for the management of rampant dental caries. An oral examination revealed pale conjunctiva, bruising of lips, and depapillation of tongue indicating an underlying condition of anemia. The poor oral condition due to topical and systemic immunosuppressants was seriously aggravated, and rampant caries developed rapidly, affecting all newly erupted, permanent teeth. The teeth were hypersensitive and halitosis was apparent. Strategies for oral health education and diet modification were given to the patient. Xylitol chewing gum was used to stimulate saliva flow to promote remineralization of teeth. Silver diamine fluoride was topically applied to arrest rampant caries and to relieve pain from hypersensitivity. Carious teeth with pulpal involvement were endodontically treated. Stainless steel crowns were provided on molars to restore chewing function, and polycarbonate crowns were placed on premolars, upper canines and incisors. This case report demonstrates success in treating a young teenager with severe rampant dental decay by contemporary caries control and preventive strategy.

  2. METHOD AND FLUX COMPOSITION FOR TREATING URANIUM

    DOEpatents

    Foote, F.

    1958-08-23

    ABS>A flux composition is described fer use with molten uranium or uranium alloys. The flux consists of about 46 weight per cent calcium fiuoride, 46 weight per cent magnesium fluoride and about 8 weight per cent of uranium tetrafiuoride.

  3. PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM

    DOEpatents

    Connick, R.E.; Gofman, J.W.; Pimentel, G.C.

    1959-11-10

    Processes are described for preparing plutonium, particularly processes of separating plutonium from uranium and fission products in neutron-irradiated uraniumcontaining matter. Specifically, plutonium solutions containing uranium, fission products and other impurities are contacted with reducing agents such as sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ferrous ion whereby the plutoninm is reduced to its fluoride-insoluble state. The reduced plutonium is then carried out of solution by precipitating niobic oxide therein. Uranium and certain fission products remain behind in the solution. Certain other fission products precipitate along with the plutonium. Subsequently, the plutonium and fission product precipitates are redissolved, and the solution is oxidized with oxidizing agents such as chlorine, peroxydisulfate ion in the presence of silver ion, permanganate ion, dichromate ion, ceric ion, and a bromate ion, whereby plutonium is oxidized to the fluoride-soluble state. The oxidized solution is once again treated with niobic oxide, thus precipitating the contamirant fission products along with the niobic oxide while the oxidized plutonium remains in solution. Plutonium is then recovered from the decontaminated solution.

  4. Study of fluoride corrosion of nickel alloys

    NASA Technical Reports Server (NTRS)

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

    1969-01-01

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

  5. Effect of Silver Diamine Fluoride and Potassium Iodide Treatment on Secondary Caries Prevention and Tooth Discolouration in Cervical Glass Ionomer Cement Restoration

    PubMed Central

    Zhao, Irene Shuping; Mei, May Lei; Burrow, Michael F.; Lo, Edward Chin-Man; Chu, Chun-Hung

    2017-01-01

    This study investigated the effect of silver diamine fluoride (SDF) and potassium iodide (KI) treatment on secondary caries prevention and tooth discolouration in glass ionomer cement (GIC) restoration. Cervical GIC restorations were done on 30 premolars with: Group 1, SDF + KI; Group 2, SDF (positive control); Group 3, no treatment (negative control). After cariogenic biofilm challenge, the demineralisation of dentine adjacent to the restoration was evaluated using micro-computed tomography (micro-CT) and Fourier transform infrared (FTIR) spectroscopy. The colour of dentine adjacent to the restoration was assessed using CIELAB system at different time points. Total colour change (∆E) was calculated and was visible if ∆E > 3.7. Micro-CT showed the outer lesion depths for Groups 1, 2 and 3 were 91 ± 7 µm, 80 ± 7 µm and 119 ± 8 µm, respectively (p < 0.001; Group 2 < Group 1 < Group 3). FTIR found that there was a significant difference in amide I-to-hydrogen phosphate ratio among the three groups (p < 0.001; Group 2 < Group 1 < Group 3). ∆E of Groups 1, 2 and 3 after biofilm challenge were 22.5 ± 4.9, 70.2 ± 8.3 and 2.9 ± 0.9, respectively (p < 0.001; Group 3 < Group 1 < Group 2). SDF + KI treatment reduced secondary caries formation on GIC restoration, but it was not as effective as SDF treatment alone. Moreover, a perceptible staining on the restoration margin was observed, but the intensity of discolouration was less than that with solely SDF treatment. PMID:28178188

  6. Caries arresting effect of silver diamine fluoride on dentine carious lesion with S. mutans and L. acidophilus dual-species cariogenic biofilm.

    PubMed

    Mei, May-Lei; Chu, Chun-Hung; Low, Kan-Hung; Che, Ching-Ming; Lo, Edward-Chin-Man

    2013-11-01

    This in vitro study investigated the effects of silver diamine fluoride (SDF) on dentine carious lesion with cariogenic biofilm. Thirty human dentine blocks were inoculated with Streptococcus mutans and Lactobacillus acidophilus dual-species biofilm to create carious lesion. They were equally divided into test and control group to receive topical application of SDF and water. After incubation anaerobically using micro-well plate at 37oC for 7 days, the biofilms were evaluated for kinetics, morphology and viability by colony forming units (CFU), scanning electron microscopy (SEM), and confocal microscopy (CLSM), respectively. The carious lesion underwent crystal characteristics analysis, evaluation of the changes in chemical structure and density of collagen fibrils using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and immune-labeling. The log CFU of S. mutans and L. acidophilus in the test group was significantly lower than control group. SEM and CLSM showed confluent biofilm in control group, but not in test group. XRD showed the loss of crystallinity of dentine due to the dissolution of hydroxyapatite crystal structure in test group was less than control group. FTIR showed that log [Amide I: HPO42-] for test vs. control group was 0.31±0.10 vs. 0.57±0.13 (p<0.05). The gold-labeling density in test vs. control group was 8.54±2.44/µm2 vs. 12.91±4.24/µm2 (p=0.04). SDF had antimicrobial activity against the cariogenic biofilms and reduced demineralization of dentine.

  7. Effect of Silver Diamine Fluoride and Potassium Iodide Treatment on Secondary Caries Prevention and Tooth Discolouration in Cervical Glass Ionomer Cement Restoration.

    PubMed

    Zhao, Irene Shuping; Mei, May Lei; Burrow, Michael F; Lo, Edward Chin-Man; Chu, Chun-Hung

    2017-02-06

    This study investigated the effect of silver diamine fluoride (SDF) and potassium iodide (KI) treatment on secondary caries prevention and tooth discolouration in glass ionomer cement (GIC) restoration. Cervical GIC restorations were done on 30 premolars with: Group 1, SDF + KI; Group 2, SDF (positive control); Group 3, no treatment (negative control). After cariogenic biofilm challenge, the demineralisation of dentine adjacent to the restoration was evaluated using micro-computed tomography (micro-CT) and Fourier transform infrared (FTIR) spectroscopy. The colour of dentine adjacent to the restoration was assessed using CIELAB system at different time points. Total colour change (∆E) was calculated and was visible if ∆E > 3.7. Micro-CT showed the outer lesion depths for Groups 1, 2 and 3 were 91 ± 7 µm, 80 ± 7 µm and 119 ± 8 µm, respectively (p < 0.001; Group 2 < Group 1 < Group 3). FTIR found that there was a significant difference in amide I-to-hydrogen phosphate ratio among the three groups (p < 0.001; Group 2 < Group 1 < Group 3). ∆E of Groups 1, 2 and 3 after biofilm challenge were 22.5 ± 4.9, 70.2 ± 8.3 and 2.9 ± 0.9, respectively (p < 0.001; Group 3 < Group 1 < Group 2). SDF + KI treatment reduced secondary caries formation on GIC restoration, but it was not as effective as SDF treatment alone. Moreover, a perceptible staining on the restoration margin was observed, but the intensity of discolouration was less than that with solely SDF treatment.

  8. Prevention of secondary caries using silver diamine fluoride treatment and casein phosphopeptide-amorphous calcium phosphate modified glass-ionomer cement.

    PubMed

    Zhao, Irene Shuping; Mei, May Lei; Burrow, Michael F; Lo, Edward Chin-Man; Chu, Chun-Hung

    2017-02-01

    To study the effect of silver diamine fluoride (SDF) treatment and incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a glass-ionomer cement (GIC) to prevent secondary caries. A cervical cavity was prepared on 32 premolars for the following restoration groups: group 1, conventional GIC restoration; group 2, SDF (38%) treatment and conventional GIC restoration; group 3, CPP-ACP (3%) modified GIC; and group 4, SDF treatment and CPP-ACP modified GIC. The restored teeth were thermal-cycled before undergoing a multi-species cariogenic biofilm challenge. The restored teeth were examined by micro-computed tomography (micro-CT), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and Fourier transform infrared (FTIR) spectroscopy. Data were analyzed by two-way ANOVA. Micro-CT determined outer lesion depths for groups 1-4 were: 123±6μm, 87±7μm, 79±3μm and 68±5μm respectively. An interaction effect on the outer lesion depth was found between the restorative materials and SDF treatment (p<0.001). Both SDF treatment and modification with CPP-ACP had a significant effect on outer lesion depth (p<0.001). SEM/EDX showed an increase of calcium and phosphorus at the root dentine adjacent to the restoration in groups 3 and 4 (CPP-ACP modified GIC). FTIR revealed that SDF treatment and CPP-ACP modified GIC had a significant effect on amide I-to-hydrogen phosphate ratio on the material-root interface (p=0.001). SDF treatment and incorporation of CPP-ACP into GIC restorative material can prevent secondary root caries development. The results provide useful information to dentists in formulating clinical management protocols and material when treating root caries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Magnesium fluoride recovery method

    DOEpatents

    Gay, Richard L.; McKenzie, Donald E.

    1989-01-01

    A method of obtaining magnesium fluoride substantially free from radioactive uranium from a slag containing the same and having a radioactivity level of at least about 7000 pCi/gm. The slag is ground to a particle size of about 200 microns or less. The ground slag is contacted with an acid under certain prescribed conditions to produce a liquid product and a particulate solid product. The particulate solid product is separated from the liquid and treated at least two more times with acid to produce a solid residue consisting essentially of magnesium fluoride substantially free of uranium and having a residual radioactivity level of less than about 1000 pCi/gm. In accordance with a particularly preferred embodiment of the invention a catalyst and an oxidizing agent are used during the acid treatment and preferably the acid is sulfuric acid having a strength of about 1.0 Normal.

  10. Optimal Fluoridation

    PubMed Central

    Lee, John R.

    1975-01-01

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

  11. Volatile fluoride process for separating plutonium from other materials

    DOEpatents

    Spedding, F. H.; Newton, A. S.

    1959-04-14

    The separation of plutonium from uranium and/or fission products by formation of the higher fluorides off uranium and/or plutonium is described. Neutronirradiated uranium metal is first converted to the hydride. This hydrided product is then treated with fluorine at about 315 deg C to form and volatilize UF/sub 6/ leaving plutonium behind. Thc plutonium may then be separated by reacting the residue with fluorine at about 5004DEC and collecting the volatile plutonium fluoride thus formed.

  12. VOLATILE FLUORIDE PROCESS FOR SEPARATING PLUTONIUM FROM OTHER MATERIALS

    DOEpatents

    Spedding, F.H.; Newton, A.S.

    1959-04-14

    The separation of plutonium from uranium and/or tission products by formation of the higher fluorides of uranium and/or plutonium is discussed. Neutronirradiated uranium metal is first convcrted to the hydride. This hydrided product is then treatced with fluorine at about 315 deg C to form and volatilize UF/sup 6/ leaving plutonium behind. The plutonium may then be separated by reacting the residue with fluorine at about 500 deg C and collecting the volatile plutonium fluoride thus formed.

  13. An ex vivo study to evaluate the remineralizing and antimicrobial efficacy of silver diamine fluoride and glass ionomer cement type VII for their proposed use as indirect pulp capping materials – Part I

    PubMed Central

    Gupta, A; Sinha, N; Logani, A; Shah, N

    2011-01-01

    Aim: Indirect pulp capping (IPC) preserves the pulp vitality by disinfecting and remineralizing remaining carious dentin. In the present study, glass ionomer (GC, FUJI VII) and silver diamine fluoride (SDF) were tested and compared to calcium hydroxide for their antimicrobial efficacy and remineralizing potential. Materials and Methods: Dentin disks prepared from 45 freshly extracted first premolars were divided into three groups (n = 15). Each disk was cut into two equal parts, in which one half formed the control. Thirty dentin samples were used for ion estimation and the other 15 for microhardness testing. Atomic absorption spectrophotometry, colorimetric and potentiometric titration analyses were performed for calcium, phosphate and fluoride ion detection, respectively. The antimicrobial efficacy was analyzed using pure culture of Streptococcus mutans and mixed flora. Results: Increase in the levels of calcium and phosphate ions was the highest in calcium hydroxide group. Both SDF and GC VII groups showed significant increase in fluoride ion levels. Samples treated with GC VII showed maximum increase in micro hardness. The highest zone of bacterial inhibition was found with SDF group. Conclusions: This in vitro study documented the remineralizing, re-hardening and antimicrobial efficacy of both SDF and GC VII and hence can act as effective IPC materials. PMID:21814348

  14. An ex vivo study to evaluate the remineralizing and antimicrobial efficacy of silver diamine fluoride and glass ionomer cement type VII for their proposed use as indirect pulp capping materials - Part I.

    PubMed

    Gupta, A; Sinha, N; Logani, A; Shah, N

    2011-04-01

    Indirect pulp capping (IPC) preserves the pulp vitality by disinfecting and remineralizing remaining carious dentin. In the present study, glass ionomer (GC, FUJI VII) and silver diamine fluoride (SDF) were tested and compared to calcium hydroxide for their antimicrobial efficacy and remineralizing potential. Dentin disks prepared from 45 freshly extracted first premolars were divided into three groups (n = 15). Each disk was cut into two equal parts, in which one half formed the control. Thirty dentin samples were used for ion estimation and the other 15 for microhardness testing. Atomic absorption spectrophotometry, colorimetric and potentiometric titration analyses were performed for calcium, phosphate and fluoride ion detection, respectively. The antimicrobial efficacy was analyzed using pure culture of Streptococcus mutans and mixed flora. Increase in the levels of calcium and phosphate ions was the highest in calcium hydroxide group. Both SDF and GC VII groups showed significant increase in fluoride ion levels. Samples treated with GC VII showed maximum increase in micro hardness. The highest zone of bacterial inhibition was found with SDF group. This in vitro study documented the remineralizing, re-hardening and antimicrobial efficacy of both SDF and GC VII and hence can act as effective IPC materials.

  15. URANIUM RECOVERY PROCESS

    DOEpatents

    Stevenson, J.W.; Werkema, R.G.

    1959-07-28

    The recovery of uranium from magnesium fluoride slag obtained as a by- product in the production of uranium metal by the bomb reduction prccess is presented. Generally the recovery is accomplished by finely grinding the slag, roasting ihe ground slag air, and leaching the roasted slag with a hot, aqueous solution containing an excess of the sodium bicarbonate stoichiometrically required to form soluble uranium carbonate complex. The roasting is preferably carried out at between 425 and 485 deg C for about three hours. The leaching is preferably done at 70 to 90 deg C and under pressure. After leaching and filtration the uranium may be recovered from the clear leach liquor by any desired method.

  16. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods.

  17. Studies of Recovery Processes for Western Uranium Bearing Ores: III. The Recovery of Uranium and Vanadium from Acid Leach Liquid Liquors of Carnotite Ores,

    DTIC Science & Technology

    2007-11-02

    Tests are reported on hydrolytic precipitation of uranium and precipitation of uranyl, arsenate, and vanadate; uranium peroxide; uranous fluoride, oxalate, and p-toluenesulfinate; and ferrous, ferric, and lead vanadates.

  18. PROCESS FOR PRODUCTION OF URANIUM

    DOEpatents

    Crawford, J.W.C.

    1959-09-29

    A process is described for the production of uranium by the autothermic reduction of an anhydrous uranium halide with an alkaline earth metal, preferably magnesium One feature is the initial reduction step which is brought about by locally bringing to reaction temperature a portion of a mixture of the reactants in an open reaction vessel having in contact with the mixture a lining of substantial thickness composed of calcium fluoride. The lining is prepared by coating the interior surface with a plastic mixture of calcium fluoride and water and subsequently heating the coating in situ until at last the exposed surface is substantially anhydrous.

  19. RECOVERY OF URANIUM VALUES FROM RESIDUES

    DOEpatents

    Schaap, W.B.

    1959-08-18

    A process is described for the recovery of uranium from insoluble oxide residues resistant to repeated leaching with mineral acids. The residue is treated with gaseous hydrogen fluoride, then with hydrogen and again with hydrogen fluoride, preferably at 500 to 700 deg C, prior to the mineral acid leaching.

  20. PRODUCTION OF URANIUM HEXAFLUORIDE

    DOEpatents

    Fowler, R.D.

    1957-08-27

    A process for the production of uranium hexafluoride from the oxides of uranium is reported. In accordance with the method, the higher oxides of uranium may be reduced to uranium dioxide (UO/sub 2/), the latter converted into uranium tetrafluoride by reaction with hydrogen fluoride, and the UF/sub 4/ converted to UF/sub 6/ by reaction with a fluorinating agent, such as CoF/sub 3/. The UO/sub 3/ or U/sub 3/O/sub 8/ is placed in a reac tion chamber in a copper boat or tray enclosed in a copper oven, and heated to 500 to 650 deg C while hydrogen gas is passed through the oven. After nitrogen gas is used to sweep out the hydrogen and the water vapor formed, and while continuing to inaintain the temperature between 400 deg C and 600 deg C, anhydrous hydrogen fluoride is passed through. After completion of the conversion of UO/sub 2/ to UF/sub 4/ the temperature of the reaction chamber is lowered to about 400 deg C or less, the UF/sub 4/ is mixed with the requisite quantity of CoF/sub 3/, and after evacuating the chamber, the mixture is heated to 300 to 400 deg C, and the resulting UF/sub 6/ is led off and delivered to a condenser.

  1. PREPARATION OF URANIUM TRIOXIDE

    DOEpatents

    Buckingham, J.S.

    1959-09-01

    The production of uranium trioxide from aqueous solutions of uranyl nitrate is discussed. The uranium trioxide is produced by adding sulfur or a sulfur-containing compound, such as thiourea, sulfamic acid, sulfuric acid, and ammonium sulfate, to the uranyl solution in an amount of about 0.5% by weight of the uranyl nitrate hexahydrate, evaporating the solution to dryness, and calcining the dry residue. The trioxide obtained by this method furnished a dioxide with a considerably higher reactivity with hydrogen fluoride than a trioxide prepared without the sulfur additive.

  2. Carcinogenesis of Depleted Uranium Fragments.

    DTIC Science & Technology

    1996-02-01

    P. W. Morrow, B. J. Panner and R. B. Baggs (eds.): Nephrotoxicity of Uranyl Fluoride and Reversibility of Renal Injury in the Rat. NUREG /CR-4951...Accidental Exposure to Uranium Hexafluoride. NUREG /CR-5566, PNL-7328, Prepared for U.S. Nuclear Regulatory Commission, Washington, DC, 1990. Foulkes, E. C...Hydrolysis Products of Uranium Hexafluoride, NUREG /CR-2268, RH, Prepared for Division of Health Siting and Waste Management, Washington, DC, 1982. 20 Nothdurft

  3. The effectiveness of the biannual application of silver nitrate solution followed by sodium fluoride varnish in arresting early childhood caries in preschool children: study protocol for a randomised controlled trial.

    PubMed

    Chu, Chun-Hung; Gao, Sherry Shiqian; Li, Samantha Ky; Wong, May Cm; Lo, Edward Cm

    2015-09-25

    The application of 38 % silver diamine fluoride (SDF) has been shown to be effective in arresting early childhood caries (ECC). Since SDF is not available in certain countries, some dentists use adjunctive application of 25 % silver nitrate (AgNO3) and 5 % sodium fluoride (NaF) to arrest ECC. This randomised controlled trial will systematically compare the efficacy of a 25 % AgNO3 solution followed by 5 % NaF varnish with that of a 38 % SDF solution in arresting ECC when applied at half-yearly intervals over a 30-month period. This study is a randomised, double-blinded, non-inferiority clinical trial. The hypothesis tested is that adjunctive application of 25 % AgNO3 followed by 5 % NaF is at least not appreciably worse than a 38 % SDF in arresting ECC. Approximately 3100 kindergarten children aged 3-4 years will be screened and at least 1070 children with caries will be recruited. This sample size is sufficient for an appropriate statistical analysis (power at 90 % (β = 0.10) with a 2-sided type-I error of α = 0.05), allowing for an overall 20 % drop-out rate. The children will be randomly allocated into 2 groups to treat their caries over a 30-month period: Group A - biannual adjunctive application of a 25 % AgNO3 solution and a 5 % NaF varnish, and Group B - biannual adjunctive application of a 38 % SDF solution followed by a placebo varnish. Clinical examinations will be conducted at 6-month intervals. Primary outcome measured is the number of active caries surfaces which are arrested. Information on confounding factors such as oral hygiene habits will be collected through a parental questionnaire. We expect that adjunctive application of 25 % AgNO3 solution and 5 % NaF varnish and of 38 % SDF solution can both effectively arrest ECC. Lower concentrations of silver and fluoride are contained in 25 % AgNO3 and 5 % NaF, respectively, than in 38 % SDF; therefore, AgNO3/NaF are more favourable for use in young children. Because its use for caries management is

  4. Mild hydrothermal crystal growth of new uranium(IV) fluorides, Na3.13Mg1.43U6F30 and Na2.50Mn1.75U6F30: Structures, optical and magnetic properties

    NASA Astrophysics Data System (ADS)

    Yeon, Jeongho; Smith, Mark D.; Tapp, Joshua; Möller, Angela; zur Loye, Hans-Conrad

    2016-04-01

    Two new uranium(IV) fluorides, Na3.13Mg1.43U6F30 (1) and Na2.50Mn1.75U6F30 (2), were synthesized through an in situ mild hydrothermal route, and were structurally characterized by single crystal X-ray diffraction. The compounds exhibit complex crystal structures composed of corner- or edge-shared UF9 and MF6 (M=Mg, Mn) polyhedra, forming hexagonal channels in the three-dimensional framework, in which ordered or disordered divalent metal and sodium atoms reside. The large hexagonal voids contain the nearly regular M(II)F6 octahedra and sodium ions, whereas the small hexagonal cavities include M(II) and sodium ions on a mixed-occupied site. Magnetic susceptibility measurements yielded effective magnetic moments of 8.36 and 11.6 μB for 1 and 2, respectively, confirming the presence and oxidation states of U(IV) and Mn(II). The large negative Weiss constants indicate the spin gap between a triplet and a singlet state in the U(IV). Magnetization data as a function of applied fields revealed that 2 exhibits paramagnetic behavior due to the nonmagnetic singlet ground state of U(IV) at low temperature. UV-vis diffuse reflectance and X-ray photoelectron spectroscopy data were also analyzed.

  5. Fluoride mouthrinses and fluoride varnishes.

    PubMed

    Petersson, L G

    1993-01-01

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

  6. Effect of silver diamine fluoride and ammonium hexafluorosilicate applications with and without Er:YAG laser irradiation on the microtensile bond strength in sound and caries-affected dentin.

    PubMed

    Kucukyilmaz, Ebru; Savas, Selcuk; Akcay, Merve; Bolukbasi, Basak

    2016-01-01

    Cariostatic and preventive agents are applied to create caries-resistant dentin surfaces and may affect subsequent resin bonding. The aim of this study was to investigate the effect of different agents with and without Er:YAG laser irradiation on the microtensile bond strength (µTBS) of resin composite to sound dentin (SD) and caries-affected dentin (CAD), and to assess the morphological and chemical changes in the specimens. Ninety-six extracted molar teeth were divided into a control group (deionized water) and two experimental groups (ammonium hexafluorosilicate [SiF], silver diamine fluoride [SDF]), that subdivided according to different conditions (SD, CAD, SD+laser irradiation, CAD+laser irradiation). After treatment procedures, the teeth were restored and the µTBS was tested with a universal testing machine. Morover, 144 teeth were prepared and after treatment modalities; morphological changes of the surface were investigated and elemental analyses were performed using scanning electron microscope/energy dispersive spectroscopy (SEM-EDS). The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. SDF and SiF applications reduced the µTBS values in both the SD and CAD subgroups (P < 0.05). Laser irradiation increased the µTBS values in the SiF group and the values were adversely affected in the SDF group (P < 0.05). Fluoride content of the specimens increased in all of the treatment groups, compared with the control group. Silver content was detected only in the SDF group, and silicon was detected only in the SiF group. The µTBS values of resin composite, surface morphology and chemical characteristics of dentin were affected by the material type, dentin condition and laser irradiation and the use of SiF and SDF solutions under the resin restorations do not seem appropriate. © 2016 Wiley Periodicals, Inc.

  7. U3F12(H2O), a noncentrosymmetric uranium(IV) fluoride prepared via a convenient in situ route that creates U4+ under mild hydrothermal conditions.

    PubMed

    Yeon, Jeongho; Smith, Mark D; Sefat, Athena S; Tran, T Thao; Halasyamani, P Shiv; zur Loye, Hans-Conrad

    2013-08-05

    A new noncentrosymmetric U(4+)-containing fluoride, U3F12(H2O), has been synthesized via a mild hydrothermal route and its crystal structure determined by single-crystal X-ray diffraction. The material exhibits a complex three-dimensional structure that is based on [U6F33(H2O)2)](9-) hexanuclear building units consisting of corner- and edge-shared UF8, UF9, and UOF7 polyhedra. Powder second-harmonic generation (SHG) measurements revealed that the SHG efficiency for U3F12(H2O) is comparable to that of α-SiO2. Magnetic susceptibility measurements indicated that the U(4+)(f(2))-containing material exhibits a singlet ground state at low temperature. IR and UV-vis reflectance spectra were obtained, and the thermal behavior was investigated by thermogravimetric analysis.

  8. WET FLUORIDE SEPARATION METHOD

    DOEpatents

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

    1958-11-25

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

  9. METHOD OF PREPARING METAL FLUORIDES

    DOEpatents

    Katz, J.J.; Sheft, I.

    1959-08-11

    A method is presented for preparing the halides of elements which are relatively non-reactive with halogenating agents. The method involves reacting a mixture of an oxygen containing salt of a difficulty halogenated metal with an oxygen containing salt of an easily halogenated metal with a halogenating agent. Accordingly plutonium tetrafluoride is produced by reacting a mixture of plutonium dioxide and uranium octaoxide with bromine trifluoride. The reaction proceeds smoothly at moderate temperatures and the resulting plutonium trifluoride may be readily separated from many impurities which form volatile fluorides by volatilizing these volatile fluorides from the reaction chamber.

  10. Electroformation of uranium hemispherical shells

    SciTech Connect

    Marshall, S.L.; Redey, L.; Vandegrift, G.F.; Vissers, D.R.

    1989-11-01

    This effort was directed at developing an electrochemical process for forming uniform and dendrite-free deposits of uranium from molten salts. This process is to be used for the electroformation of free-standing hemispherical shells of uranium for nuclear applications. Electrodeposition of uranium onto a substrate was accomplished with a fused chloride mixture containing 42 wt% UCl{sub 3} and a fused chloride-fluoride mixture containing 4 wt % UF{sub 4}. Under pulsed potential control at 504{degree}C, the chloride-fluoride mixture yielded the widest range of plating conditions for which dendrites could be avoided. Bipolar current pulse plating with both electrolytes gave good results, and successful application of this technique to a large tubular cathode has been demonstrated. 24 refs., 10 figs.

  11. Compressive strength, fluoride release and recharge of fluoride-releasing materials.

    PubMed

    Xu, Xiaoming; Burgess, John O

    2003-06-01

    The compressive strength, fluoride releases and recharge profiles of 15 commercial fluoride-releasing restorative materials have been studied. The materials include glass ionomers (Fuji IX, Ketac Molar, Ketac Silver, and Miracle Mix), resin-modified glass ionomers (Fuji II LC Improved, Photac-Fil, and Vitremer), compomers (Compoglass, Dyract AP, F2000, and Hytac) and composite resins (Ariston pHc, Solitaire, Surefil and Tetric Ceram). A negative linear correlation was found between the compressive strength and fluoride release (r(2)=0.7741), i.e., restorative materials with high fluoride release have lower mechanical properties. The fluoride-releasing ability can be partially regenerated or recharged by using a topical fluoride agent. In general, materials with higher initial fluoride release have higher recharge capability (r(2)=0.7088). Five equations have been used in curve fitting to describe the cumulative fluoride release from different materials. The equation [F](c)=[F](I)(1-e(-bt))+betat best describes the cumulative fluoride release for most glass ionomers, resin-modified glass ionomers, and some high fluoride-releasing compomers and composites, whereas [F](c)=[F](I)/(t(1/2)+t)+alphat best describes the cumulative fluoride release for most compomers and composite resins. The clinic applications of different fluoride-releasing materials have also been discussed.

  12. Dentifrice Fluoride

    NASA Astrophysics Data System (ADS)

    Rakita, Philip E.

    2004-05-01

    The effectiveness of the fluoride ion in lowering the incidence of dental caries is a major factor in the field of dental health. Observations and research studies in the first half of the 20th century have lead to the widespread adoption of fluoridated water and the use of inorganic fluoride compounds in oral care products, such as toothpaste and dental rinses. This article provides a brief review of the types of compounds used and the chemistry involved.

  13. Bottled Water and Fluoride

    MedlinePlus

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

  14. Water fluoridation.

    PubMed

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

    2009-09-01

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

  15. METHOD FOR DISSOLVING ZIRCONIUM-URANIUM COMPOSITIONS

    DOEpatents

    Gens, T.A.

    1961-07-18

    A method is descrioed for treating a zirconium-- uranium composition to form a stable solution from which uranium and other values may be extracted by contacting the composition with at least a 4 molar aqueous solution of ammonium fluoride at a temperature of about 100 deg C, adding a peroxide, in incremental amounts, to the heated solution throughout the period of dissolution until all of the uranium is converted to soluble uranyl salt, adding nitric acid to the resultant solution to form a solvent extraction feed solution to convert the uranyl salt to a solvent extractable state, and thereafter recovering the uranium and other desired values from the feed solution by solvent extraction.

  16. Mortality among uranium enrichment workers

    SciTech Connect

    Brown, D.P.; Bloom, T.

    1987-01-01

    A retrospective cohort mortality study was conducted on workers at the Portsmouth Uranium Enrichment facility in Pike County, Ohio, in response to a request from the Oil, Chemical and Atomic Workers International Local 3-689 for information on long-term health effects. Primary hazards included inhalation exposure to uranyl fluoride containing uranium-235 and uranium-234, technetium-99 compounds, and hydrogen-fluoride. Uranium-238 presented a nephrotoxic hazard. Statistically significant mortality deficits based on U.S. death rates were found for all causes, accidents, violence, and diseases of nervous, circulatory, respiratory, and digestive systems. Standardized mortality rates were 85 and 54 for all malignant neoplasms and for other genitourinary diseases, respectively. Deaths from stomach cancer and lymphatic/hematopoietic cancers were insignificantly increased. A subcohort selected for greatest potential uranium exposure has reduced deaths from these malignancies. Insignificantly increased stomach cancer mortality was found after 15 years employment and after 15 years latency. Routine urinalysis data suggested low internal uranium exposures.

  17. PROCESS FOR PRODUCING URANIUM HEXAFLUORIDE

    DOEpatents

    Fowler, R.D.

    1957-10-22

    A process for the production of uranium hexafluoride from the oxides of uranium is reported. In accordance with the method the higher oxides of uranium may be reduced to uranium dioxide (UO/sub 2/), the latter converted into uranium tetrafluoride by reaction with hydrogen fluoride, and the UF/sub 4/ convented to UF/sub 6/ by reaction with a fluorinating agent. The UO/sub 3/ or U/sub 3/O/sub 8/ is placed in a reaction chamber in a copper boat or tray enclosed in a copper oven, and heated to 500 to 650 deg C while hydrogen gas is passed through the oven. The oven is then swept clean of hydrogen and the water vapor formed by means of nitrogen and then while continuing to maintain the temperature between 400 and 600 deg C, anhydrous hydrogen fluoride is passed through. After completion of the conversion to uranium tetrafluoride, the temperature of the reaction chamber is lowered to ahout 400 deg C, and elemental fluorine is used as the fluorinating agent for the conversion of UF/sub 4/ into UF/sub 6/. The fluorine gas is passed into the chamber, and the UF/sub 6/ formed passes out and is delivered to a condenser.

  18. Protactinium Fluorides, the New Class, MPaF6.

    PubMed

    Asprey, L B; Penneman, R A

    1964-08-28

    Complex fluorides of protactinium having a Pa/M ratio of one (where M = K, Rb, or NH(4)) have been prepared from concentrated solutions of HF. These MPaF(6) compounds are isostructural with the corresponding compounds of pentavalent uranium but not with the tantalum analogs. The size of protactinium (V) is but slightly larger than that of uranium (V).

  19. PROCESS FOR TREATING VOLATILE METAL FLUORIDES

    DOEpatents

    Rudge, A.J.; Lowe, A.J.

    1957-10-01

    This patent relates to the purification of uranium hexafluoride, made by reacting the metal or its tetrafluoride with fluorine, from the frequently contained traces of hydrofluoric acid. According to the present process, UF/sub 6/ containing as an impurity a small amount of hydrofluoric acid, is treated to remove such impurity by contact with an anhydrous alkali metal fluoride such as sodium fluoride. In this way a non-volatile complex containing hydrofluoric acid and the alkali metal fluoride is formed, and the volatile UF /sub 6/ may then be removed by distillation.

  20. Current status of fluoride volatility method development

    SciTech Connect

    Uhlir, J.; Marecek, M.; Skarohlid, J.

    2013-07-01

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

  1. Thermodynamic modeling of hydrogen fluoride production relevant to actinide residue treatment

    SciTech Connect

    West, M.H.; Axler, K.M.

    1995-02-01

    This report addresses issues specific to generation of hydrogen fluoride via reaction of calcium fluoride with sulfuric acid. This process has been established on a commercial scale and is under consideration for treatment of calcium fluoride residues from uranium processing. Magnesium fluoride slags are also available as a product of uranium processing. The technique of using sulfuric acid for the production of hydrogen fluoride from magnesium fluoride is also under consideration as a residue processing scheme. In the current study, thermodynamic modeling was used to investigate these chemical processing systems. Results presented herein reveal information relevant to selection of processing temperatures and conditions. Details include predicted effects in system composition based on operating temperatures for both the calcium fluoride and the magnesium fluoride systems.

  2. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F.; Sparrow, Robert W.

    1991-01-01

    The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

  3. Other Fluoride Products

    MedlinePlus

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

  4. URANIUM RECOVERY

    DOEpatents

    Fitch, F.T.; Cruikshank, A.J.

    1958-10-28

    A process for recovering uranium from a solution of a diethyl dithiocarbaruate of uranium in an orgakic solvent substantially immiscible with water is presented. The process comprises brlnging the organic solutlon into intimate contact wlth an aqueous solution of ammonium carbonate, whereby the uranium passes to the aqueous carbonate solution as a soluble uranyl carbonate.

  5. Method for cleaning bomb-reduced uranium derbies

    DOEpatents

    Banker, J.G.; Wigginton, H.L.; Beck, D.E.; Holcombe, C.E.

    The concentration of carbon in uranium metal ingots induction cast from derbies prepared by the bomb-reduction of uranium tetrafluoride in the presence of magnesium is effectively reduced to less than 100 ppM by removing residual magnesium fluoride from the surface of the derbies prior to casting. This magnesium fluoride is removed from the derbies by immersing them in an alkali metal salt bath which reacts with and decomposes the magnesium fluoride. A water quenching operation followed by a warm nitric acid bath and a water rinse removes the residual salt and reaction products from the derbies.

  6. Method for cleaning bomb-reduced uranium derbies

    DOEpatents

    Banker, John G.; Wigginton, Hubert L.; Beck, David E.; Holcombe, Cressie E.

    1981-01-01

    The concentration of carbon in uranium metal ingots induction cast from derbies prepared by the bomb-reduction of uranium tetrafluoride in the presence of magnesium is effectively reduced to less than 100 ppm by removing residual magnesium fluoride from the surface of the derbies prior to casting. This magnesium fluoride is removed from the derbies by immersing them in an alkali metal salt bath which reacts with and decomposes the magnesium fluoride. A water quenching operation followed by a warm nitric acid bath and a water rinse removes the residual salt and reaction products from the derbies.

  7. Electrolytic process for preparing uranium metal

    DOEpatents

    Haas, Paul A.

    1990-01-01

    An electrolytic process for making uranium from uranium oxide using Cl.sub.2 anode product from an electrolytic cell to react with UO.sub.2 to form uranium chlorides. The chlorides are used in low concentrations in a melt comprising fluorides and chlorides of potassium, sodium and barium in the electrolytic cell. The electrolysis produces Cl.sub.2 at the anode that reacts with UO.sub.2 in the feed reactor to form soluble UCl.sub.4, available for a continuous process in the electrolytic cell, rather than having insoluble UO.sub.2 fouling the cell.

  8. National uranium resource evaluation, Kalispell Quadrangle, Montana

    SciTech Connect

    Fleshman, B.R.; Siegmund, B.L.

    1982-03-01

    The Kalispell Quadrangle, Montana, was evaluated using criteria developed for the National Uranium Resource Evaluation program for the purpose of identifying and delineating areas containing geologic environments favorable for uranium deposits. Reconnaissance and detailed investigations included the evaluation of reported uranium occurrences, geochemical sampling, and field evaluation of hydrogeochemical and stream-sediment anomalies. Results of the investigations indicate that two areas have potential for uranium deposits in or related to plutonic rocks. Both areas contain peralkaline plutonic rocks and are possibly spatially and genetically related to a larger alkaline-ultramafic complex. The nonradioactive plutonic rocks of the Bobtail stock are possibly related to this larger complex but are considered unfavorable for uranium deposits. Precambrian volcanic and metasedimentary rocks outside areas containing polymetallic vein-type silver-lead-zinc enrichment are also considered unfavorable for uranium deposits. Paleozoic, Mesozoic, and Cenozoic sedimentary rocks and Quaternary deposits are also unfavorable.

  9. Evaluation of microshear bond strength and nanoleakage of etch-and-rinse and self-etch adhesives to dentin pretreated with silver diamine fluoride/potassium iodide: An in vitro study.

    PubMed

    Selvaraj, Karthik; Sampath, Vidhya; Sujatha, V; Mahalaxmi, S

    2016-01-01

    The aim of this in vitro study was to comparatively evaluate the microshear bond strength (MSBS) of etch-and-rinse and self-etch (ER and SE) bonding systems to dentin pretreated with silver diamine fluoride/potassium iodide (SDF/KI) and nanoleakage at the resin-dentin interface using transmission electron microscope (TEM). Seventy-two dentin slabs of 3 mm thickness were prepared from extracted human permanent third molars and divided into four groups (n = 18) based on the dentin surface treatment as follows: (1) ER adhesive bonding without dentin pretreatment; (2) SDF/KI pretreatment of dentin followed by ER adhesive bonding; (3) SE adhesive bonding without dentin pretreatment; and (4) SDF/KI pretreatment of dentin followed by SE adhesive bonding. Resin composite was built on the dentin slabs to a height of 4 mm incrementally, and dentin-composite beams of approximately 1 mm 2 cross-sectional area were prepared. The beams were subjected to MSBS analysis, and the fractured surface was observed under scanning electron microscope to determine the mode of failure. The resin-dentin interface was examined under TEM for evaluation of nanoleakage. One-way ANOVA followed by Tukey's post hoc multiple comparison tests. Pretreatment of dentin with SDF/KI increased the MSBS of ER and SE adhesives, though not statistically significant, except between Groups 2 and 3. In all the groups, the predominant mode of failure was adhesive followed by cohesive in resin, mixed and cohesive in dentin. TEM examination of resin-dentin interface showed that pretreatment with 38% SDF/KI reduced nanoleakage regardless of the type of bonding system used. Pretreatment of dentin with SDF/KI minimized nanoleakage at the resin-dentin interface without adversely affecting the bond strength of resin composite to dentin.

  10. SEPARATION OF PLUTONIUM VALUES FROM URANIUM AND FISSION PRODUCT VALUES

    DOEpatents

    Maddock, A.G.; Booth, A.H.

    1960-09-13

    Separation of plutonium present in small amounts from neutron irradiated uranium by making use of the phenomenon of chemisorption is described. Plutonium in the tetravalent state is chemically absorbed on a fluoride in solid form. The steps for the separation comprise dissolving the irradiated uranium in nitric acid, oxidizing the plutonium in the resulting solution to the hexavalent state, adding to the solution a soluble calcium salt which by the common ion effect inhibits dissolution of the fluoride by the solution, passing the solution through a bed or column of subdivided calcium fluoride which has been sintered to about 8OO deg C to remove the chemisorbable fission products, reducing the plutonium in the solution thus obtained to the tetravalent state, and again passing the solution through a similar bed or column of calcium fluoride to selectively absorb the plutonium, which may then be recovered by treating the calcium fluoride with a solution of ammonium oxalate.

  11. METHOD OF PREPARING URANIUM PENTA-FLUORIDE

    DOEpatents

    Hobbs, W.E.

    1962-05-22

    This invention relates to a method for the preparation of UF/sub 5/, Gaseous UF/sub 6/ and gaseous HBr are contacted under anhydrous conditions and at a UF/sub 6/-to-HBr molar ratio of at least approximately 1.7. Beta UF/sub 5/ is obtained at a reaction temperature under 125 deg C, alpha UF5 at a temperature over 1505 deg C, and a mixture of the alpha and beta forms at intermediate (125 te 150 DELTA Etemperatures. (AEC)

  12. Fluoridated Water

    MedlinePlus

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

  13. Treatment of effluents from uranium oxide production.

    PubMed

    Ladeira, A C Q; Gonçalves, J S; Morais, C A

    2011-01-01

    The nuclear fuel cycle comprises a series of industrial processes which involve the production of electricity from uranium in nuclear power reactors. In Brazil the conversion of uranium hexafluoride (UF6) into uranium dioxide (UO2) takes place in Resende (RJ) at the Nuclear Fuel Factory (FCN). The process generates liquid effluents with significant concentrations of uranium, which might be treated before being discharged into the environment. This study investigates the recovery of uranium from three distinct liquid effluents: one with a high carbonate content and the other with an elevated fluoride concentration. This paper also presents a study on carbonate removal from an effluent that consists of a water-methanol solution generated during the filtration of the yellow cake (ammonium uranyl tricarbonate). The results showed that: (1) the uranium from the carbonated solution can be recovered through the ion exchange technique using the strong base anionic resin IRA 910-U, as the carbonate has been removed as CO2 after heating; (2) the most suitable technique to recover uranium from the fluoride solution is its precipitation as (NH4)2UO4F2 (ammonium fluorouranate peroxide), (3) the solution free of carbonate can be added to the fluoride solution and the uranium from the final solution can be recovered by precipitation as ammonium fluorouranate peroxide as well; (4) the carbonate from the water-methanol solution can be recovered as calcium carbonate through the addition of calcium chloride, or it can be recovered as ammonium sulphate through the addition of sulphuric acid. The ammonium sulphate product can be used as a fertilizer.

  14. Determination of Fluoride and Chloride in NU Sample Matrices by Ion Chromatography

    SciTech Connect

    Ray, R.

    2003-05-21

    This study is a demonstration of fluoride and chloride determinations in natural uranium (NU) sample matrices as part of technical task request FSS-ALD-2002-00025 deliverable from Central Laboratory Services.

  15. Determination of Fluoride and Chloride in LEU Sample Matrices by Ion Chromatography

    SciTech Connect

    Ray, R.

    2002-12-06

    This study is a demonstration of fluoride and chloride determinations in Low Enriched Uranium sample matrices as part of technical task request FSS-ALD-2002-00025 deliverable from Central Laboratory Services.

  16. Caries remineralisation and arresting effect in children by professionally applied fluoride treatment - a systematic review.

    PubMed

    Gao, Sherry Shiqian; Zhang, Shinan; Mei, May Lei; Lo, Edward Chin-Man; Chu, Chun-Hung

    2016-02-01

    As a low-cost and easily operated treatment, the use of professionally applied topical fluoride was approved for preventing dental caries and remineralising early enamel caries or white spot lesions. It is also used to arrest dentine caries. The aim of this study is to investigate the clinical efficacy of professional fluoride therapy in remineralising and arresting caries in children. A systematic search of publications from 1948 to 2014 was conducted using four databases: PubMed, Cochrane Library, ISI Web of Science and Embase. The key words used were (fluoride) AND (remineralisation OR remineralization OR arresting) AND (children caries OR early childhood caries). The title and abstract of initially identified publications were screened. Clinical trials about home-use fluorides, laboratory studies, case reports, reviews, non-English articles and irrelevant studies were excluded. The full texts of the remaining papers were retrieved. Manual screening was conducted on the bibliographies of the remaining papers to identify relevant articles. A total of 2177 papers were found, and 17 randomised clinical trials were included in this review. Ten studies investigated the remineralising effect on early enamel caries using silicon tetrafluoride, fluoride gel, silver diamine fluoride or sodium fluoride. Seven studies reported an arresting effect on dentine caries using silver diamine fluoride or nano-silver fluoride. Meta-analysis was performed on four papers using 5 % sodium fluoride varnish to remineralise early enamel caries, and the overall percentage of remineralised enamel caries was 63.6 % (95 % CI: 36.0 % - 91.2 %; p < 0.001). Meta-analysis was also performed on five papers using 38 % silver diamine fluoride to arrest dentine caries and the overall proportion of arrested dentine caries was 65.9 % (95 % CI: 41.2 % - 90.7 %; p < 0.001). Professionally applied 5 % sodium fluoride varnish can remineralise early enamel caries and 38 % silver diamine fluoride is

  17. Uranium in Wheeler Basin, Grand County, Colorado

    USGS Publications Warehouse

    Young, E.J.

    1982-01-01

    Two kinds of radioactive anomalies are found in Wheeler Basin, both of which consist of biotite concentrations in Precambrian rocks, but the ones in migmatized biotite gneiss contain uraninite and the ones in Silver Plume Granite probably do not. At least 18 new uranium occurrences were found, most of which are less than a square meter. These discoveries enlarge the uraniferous area reported by Young and Hauff in 1975. Uranium in these biotite concentrations occurs in several modes: as uraninite grains; in accessory minerals, such as zircon; in fractures in plagioclase; and along grain boundaries and in cleavage openings in mica. Uranium mineralogy in the fractures, grain boundaries, and micas is not known. Yellow, secondary uranium minerals are seen locally on outcrop. Relative to crustal abundance, the radioactive biotite concentrations in migmatized biotite gneiss show depletion in Ca, Sr, Na, and, locally, Cu, but pronounced enrichment in U and Mo, and moderate enrichment in Pb, Ag, Th, and REE. The radioactive biotite concentrations in the Silver Plume Granite show pronounced enrichment in Th, and moderate enrichment in U, Sn, Zr, and Ag. Enrichment in light REE predominates over heavy REE. As U is more abundant in biotite concentrations in migmatized biotite gneiss than in biotite concentrations in Silver Plume Granite, I have concluded that U in the migmatized biotite gneiss was present before intrusion of the Silver Plume Granite, and that metamorphic effects of the Silver Plume intrusion remobilized U to form pockets of enrichment (biotite concentrations).

  18. Recovery of protactinium from molten fluoride nuclear fuel compositions

    DOEpatents

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

    1973-12-25

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

  19. URANIUM COMPOSITIONS

    DOEpatents

    Allen, N.P.; Grogan, J.D.

    1959-05-12

    This patent relates to high purity uranium alloys characterized by improved stability to thermal cycling and low thermal neutron absorption. The high purity uranium alloy contains less than 0.1 per cent by weight in total amount of any ore or more of the elements such as aluminum, silicon, phosphorous, tin, lead, bismuth, niobium, and zinc.

  20. Optical properties of ammonium uranyl fluoride characterized by photoluminescence and photoacoustic spectroscopy.

    PubMed

    Gupta, Santosh K; Dhobale, A R; Natarajan, V; Godbole, S V

    2014-01-03

    PL and PAS studies were performed on uranyl compounds viz. uranium oxalate, uranium fluoride and ammonium uranyl fluoride. PL and PAS spectrum of ammonium uranyl fluoride is being reported for the first time. Ammonium uranyl fluoride is blue shifted with respect to uranyl fluoride, as a result of ammonium bonding. The vibronic separations were determined in the excited state and the ground state using excitation/PA spectra and emission spectra respectively. Fluorescence decay data could be fitted only with biexponential decay in all of these compounds indicating the presence of two different environments in these compounds. Low temperature luminescence leads to enhancement in emission intensity and lifetime value. The temperature dependence studies of average fluorescence lifetimes of ammonium uranyl are described in this paper. Based on this studies activation energy value for ammonium uranyl fluoride at which (3)∏ and (1)Σ potential surfaces will cross is calculated.

  1. Fluoride absorption: independence from plasma fluoride levels

    SciTech Connect

    Whitford, G.M.; Williams, J.L.

    1986-04-01

    The concept that there are physiologic mechanisms to homeostatically regulate plasma fluoride concentrations has been supported by results in the literature suggesting an inverse relationship between plasma fluoride levels and the absorption of the ion from the gastrointestinal tract of the rat. The validity of the relationship was questioned because of possible problems in the experimental design. The present work used four different methods to evaluate the effect of plasma fluoride levels on the absorption of the ion in rats: (i) the percentage of the daily fluoride intake that was excreted in the urine; (ii) the concentration of fluoride in femur epiphyses; (iii) the net areas under the time-plasma fluoride concentration curves after intragastric fluoride doses; and (iv) the residual amounts or fluoride in the gastrointestinal tracts after the intragastric fluoride doses. None of these methods indicated that plasma fluoride levels influence the rate or the degree or fluoride absorption. It was concluded that, unless extremely high plasma fluoride levels are involved (pharmacologic or toxic doses), the absorption of the ion is independent of plasma levels. The results provide further evidence that plasma fluoride concentrations are not homeostatically regulated.

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

    PubMed

    Opydo-Szymaczek, Justyna; Opydo, Jadwiga

    2011-08-01

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

  3. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, G.G.; Kato, T.R.; Schonegg, E.

    1985-04-11

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

  4. DIRECT INGOT PROCESS FOR PRODUCING URANIUM

    DOEpatents

    Leaders, W.M.; Knecht, W.S.

    1960-11-15

    A process is given in which uranium tetrafluoride is reduced to the metal with magnesium and in the same step the uranium metal formed is cast into an ingot. For this purpose a mold is arranged under and connected with the reaction bomb, and both are filled with the reaction mixture. The entire mixture is first heated to just below reaction temperature, and thereafter heating is restricted to the mixture in the mold. The reaction starts in the mold whereby heat is released which brings the rest of the mixture to reaction temperature. Pure uranium metal settles in the mold while the magnesium fluoride slag floats on top of it. After cooling, the uranium is separated from the slag by mechanical means.

  5. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-10-07

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  6. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-01-01

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  7. PROCESS FOR DISSOLVING BINARY URANIUM-ZIRCONIUM OR ZIRCONIUM-BASE ALLOYS

    DOEpatents

    Jonke, A.A.; Barghusen, J.J.; Levitz, N.M.

    1962-08-14

    A process of dissolving uranium-- zirconium and zircaloy alloys, e.g. jackets of fuel elements, with an anhydrous hydrogen fluoride containing from 10 to 32% by weight of hydrogen chloride at between 400 and 450 deg C., preferably while in contact with a fluidized inert powder, such as calcium fluoride is described. (AEC)

  8. Salt fluoridation: a review.

    PubMed

    Pollick, Howard F

    2013-06-01

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

  9. Silver Sulfadiazine

    MedlinePlus

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  10. Fluoride and Water (For Parents)

    MedlinePlus

    ... Your 1- to 2-Year-Old Fluoride and Water KidsHealth > For Parents > Fluoride and Water A A ... to 19-year-olds continue Fluoride and the Water Supply For more than 60 years, water fluoridation ...

  11. Private Well Water and Fluoride

    MedlinePlus

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

  12. Fluoride and Water (For Parents)

    MedlinePlus

    ... Your 1- to 2-Year-Old Fluoride and Water KidsHealth > For Parents > Fluoride and Water Print A ... to 19-year-olds continue Fluoride and the Water Supply For more than 60 years, water fluoridation ...

  13. Practitioner's guide to fluoride.

    PubMed

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

    2002-10-01

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

  14. Uranium bombs

    NASA Astrophysics Data System (ADS)

    DeGroot, Gerard

    2009-11-01

    Enrico Fermi was a brilliant physicist, but he did occasionally get things wrong. In 1934 he famously bombarded a sample of uranium with neutrons. The result was astounding: the experiment had, Fermi concluded, produced element 93, later called neptunium. The German physicist Ida Noddack, however, came to an even more spectacular conclusion, namely that Fermi had split the uranium nucleus to produce lighter elements. Noddack's friend Otto Hahn judged that idea preposterous and advised her to keep quiet, since ridicule could ruin a female physicist. She ignored that advice, and was, indeed, scorned.

  15. Mild hydrothermal crystal growth of new uranium(IV) fluorides, Na{sub 3.13}Mg{sub 1.43}U{sub 6}F{sub 30} and Na{sub 2.50}Mn{sub 1.75}U{sub 6}F{sub 30}: Structures, optical and magnetic properties

    SciTech Connect

    Yeon, Jeongho; Smith, Mark D.; Tapp, Joshua; Möller, Angela; Loye, Hans-Conrad zur

    2016-04-15

    Two new uranium(IV) fluorides, Na{sub 3.13}Mg{sub 1.43}U{sub 6}F{sub 30} (1) and Na{sub 2.50}Mn{sub 1.75}U{sub 6}F{sub 30} (2), were synthesized through an in situ mild hydrothermal route, and were structurally characterized by single crystal X-ray diffraction. The compounds exhibit complex crystal structures composed of corner- or edge-shared UF{sub 9} and MF{sub 6} (M=Mg, Mn) polyhedra, forming hexagonal channels in the three-dimensional framework, in which ordered or disordered divalent metal and sodium atoms reside. The large hexagonal voids contain the nearly regular M(II)F{sub 6} octahedra and sodium ions, whereas the small hexagonal cavities include M(II) and sodium ions on a mixed-occupied site. Magnetic susceptibility measurements yielded effective magnetic moments of 8.36 and 11.6 µ{sub B} for 1 and 2, respectively, confirming the presence and oxidation states of U(IV) and Mn(II). The large negative Weiss constants indicate the spin gap between a triplet and a singlet state in the U(IV). Magnetization data as a function of applied fields revealed that 2 exhibits paramagnetic behavior due to the nonmagnetic singlet ground state of U(IV) at low temperature. UV–vis diffuse reflectance and X-ray photoelectron spectroscopy data were also analyzed. - Graphical abstract: Two new quaternary U(IV) fluorides, Na{sub 3.13}Mg{sub 1.43}U{sub 6}F{sub 30} and Na{sub 2.50}Mn{sub 1.75}U{sub 6}F{sub 30}, were crystallized via an in situ reduction step of U(VI) to U(IV) under mild hydrothermal conditions. The compounds show complex crystal structures based on the 3-D building block of U{sub 6}F{sub 30}. Magnetic property measurements revealed that the U(IV) exhibits a nonmagnetic singlet ground state at low temperature with a spin gap. - Highlights: • Na{sub 3.13}Mg{sub 1.43}U{sub 6}F{sub 30} and Na{sub 2.50}Mn{sub 1.75}U{sub 6}F{sub 30} have been synthesized and characterized. • The U(IV) fluorides exhibit complex three-dimensional crystal structures. • The

  16. Machining of uranium and uranium alloys

    SciTech Connect

    Morris, T.O.

    1981-12-14

    Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures.

  17. Uranium, natural

    Integrated Risk Information System (IRIS)

    Uranium , natural ; CASRN 7440 - 61 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

  18. URANIUM ALLOYS

    DOEpatents

    Seybolt, A.U.

    1958-04-15

    Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

  19. How Does Fluoride Work?

    MedlinePlus

    ... Work? A A A There's fluoride in your toothpaste and even in your water. But how does ... enamel from plaque and sugars. By using fluoride toothpaste, for instance, everyone can enjoy some cavity protection. ...

  20. Oxidation state determination of uranium in various uranium oxides: Photoacoustic spectroscopy complimented by photoluminescence studies

    NASA Astrophysics Data System (ADS)

    Gupta, Santosh K.; Dhobale, A. R.; Kumar, M.; Godbole, S. V.; Natarajan, V.

    2015-03-01

    Photoacoustic spectroscopy (PAS) has been utilized for the determination of U(IV). Initial experiments were carried out for determination of U(IV) in uranium tetra fluoride, and were further extended to the determination of U(IV) in uranium oxide samples having various O/M ratios like UO2.00, UO2.17, U3O8, and U3O7. All these oxides, since dark gray/black in color, were having featureless spectra in the visible region, hence solid state reaction of uranium oxide with ammonium bi-fluoride was utilized for the formation of U(IV) and U(VI) oxyfluorides, having narrow well resolved spectra, prior to estimation by Photoacoustic spectroscopy technique. The strong absorption for U(IV) complex at 630 nm was monitored using a He-Ne laser resulting in good sensitivity for determination of U(IV). It was observed that fluorinated uranium dioxide (UO2) is having spectra similar to U(IV); fluorinated uranium trioxide (UO3) is having spectra of uranyl only whereas Triuranium octoxide (U3O8) spectra consist of both U(IV) and uranyl component. This was further supported by photoluminescence studies.

  1. Uranium industry annual 1996

    SciTech Connect

    1997-04-01

    The Uranium Industry Annual 1996 (UIA 1996) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1996 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. Data on uranium raw materials activities for 1987 through 1996 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2006, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. A feature article, The Role of Thorium in Nuclear Energy, is included. 24 figs., 56 tabs.

  2. Fluoridation update 2014.

    PubMed

    Allukian, Myron; Wong, Chloe

    2014-01-01

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

  3. Fluoride content of beverages intended for infants and young children in Poland.

    PubMed

    Opydo-Szymaczek, Justyna; Opydo, Jadwiga

    2010-10-01

    Results of the studies indicate that fluoride content in beverages may be highly variable and children can consume substantial amounts of fluoride with these products. Ingestion of excessive fluoride during infancy and early childhood may cause dental fluorosis of permanent maxillary central incisors--the most aesthetically important teeth. The aim of this study was to determine the fluoride content in Polish beverages designed for infants and young children nutrition. Forty-three brands of juices and juice-flavored drinks and 23 instant teas were evaluated. Analyses were performed with the use of ion-selective fluoride electrode (09-37 type) and a RAE 111 chloride-silver reference electrode (MARAT). Fluoride concentrations in most beverages did not exceed 0.3 ppm. However, in three beverages containing tea extract levels of fluoride were higher (0.35-1.14 ppm). Consumption of these beverages could significantly increase child's fluoride exposure. Therefore, the need exists for continuous monitoring of fluoride levels in products intended for children. Listing fluoride content on beverages would be desirable. Knowledge about possible fluoride ingestion from dietary sources permits the clinician to recommend the safest schedule of fluoride treatment so as the optimal caries preventive effect can be obtained and the risk of dental fluorosis reduced.

  4. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed...) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed. The term uranium feed or natural uranium feed means natural uranium in the form of UF6 suitable for uranium...

  5. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Uranium feed; natural uranium feed...) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed. The term uranium feed or natural uranium feed means natural uranium in the form of UF6 suitable for uranium...

  6. Pit and fissure sealants or fluoride varnishes?

    PubMed

    Paglia, L

    2016-09-01

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

  7. Production of sintered porous metal fluoride pellets

    DOEpatents

    Anderson, L.W.; Stephenson, M.J.

    1973-12-25

    Porous pellets characterized by a moderately reactive crust and a softer core of higher reactivity are produced by forming agglomerates containing a metal fluoride powder and a selected amount ofwater. The metal fluoride is selected to be sinterable and essentially non-reactive with gaseous fluorinating agents. The agglomerates are contacted with a gaseous fluorinating agent under controlled conditions whereby the heat generated by localized reaction of the agent and water is limited to values effccting bonding by localized sintering. Porous pellets composed of cryolite (Na/sub 3/AlF/sub 6/) can be used to selectively remove trace quantities of niobium pentafluoride from a feed gas consisting predominantly of uranium hexafluoride. (Official Gazette)

  8. Derived enriched uranium market

    SciTech Connect

    Rutkowski, E.

    1996-12-01

    The potential impact on the uranium market of highly enriched uranium from nuclear weapons dismantling in the Russian Federation and the USA is analyzed. Uranium supply, conversion, and enrichment factors are outlined for each country; inventories are also listed. The enrichment component and conversion components are expected to cause little disruption to uranium markets. The uranium component of Russian derived enriched uranium hexafluoride is unresolved; US legislation places constraints on its introduction into the US market.

  9. Method for monitoring stack gases for uranium activity

    DOEpatents

    Beverly, C.R.; Ernstberger, E.G.

    1985-07-03

    A method for monitoring the stack gases of a purge cascade of gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases. 1 fig.

  10. Method for monitoring stack gases for uranium activity

    DOEpatents

    Beverly, Claude R.; Ernstberger, Harold G.

    1988-01-01

    A method for monitoring the stack gases of a purge cascade of a gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases.

  11. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

    SciTech Connect

    Ward, Jesse D.; Bowden, Mark; Tom Resch, C.; Eiden, Gregory C.; Pemmaraju, C. D.; Prendergast, David; Duffin, Andrew M.

    2017-01-01

    Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Non-destructive chemical analyses of these compounds is important for process and environmental monitoring and X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. These compounds have unique spectral signatures that can be used to identify unknown samples.

  12. 10 CFR Appendix J to Part 110 - Illustrative List of Uranium Conversion Plant Equipment and Plutonium Conversion Plant Equipment...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... conversion of uranium fluorides to UO2. Many key equipment items for uranium conversion plants are common to... the hot effluent gases by passing the effluent stream through a cold trap cooled to -10°C. The process... common to several segments of the chemical process industry. For example, the types of equipment employed...

  13. 10 CFR Appendix J to Part 110 - Illustrative List of Uranium Conversion Plant Equipment and Plutonium Conversion Plant Equipment...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... conversion of uranium fluorides to UO2. Many key equipment items for uranium conversion plants are common to... the hot effluent gases by passing the effluent stream through a cold trap cooled to -10°C. The process... common to several segments of the chemical process industry. For example, the types of equipment employed...

  14. Screenable silver and base metal solar cell contacts

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1980-01-01

    The metallurgical soundness of the all-metal screenable thick film electrode system is established for silver and copper electrodes. Silver fluoride was identified as a successful etchant material and is found most effective in the liquid phase (435-460 C). Best results were achieved with the eutectic alloys of dopants and semiconductors. The air-fired silver inks were strongly adherent, rugged, and solderable, whereas the hydrogen-fired silver inks had very poor adhesion. A two-step firing process was devised in which copper inks containing silver fluoride were activated in a nitrogen atmosphere, with sintering done at the same or higher temperatures in hydrogen. Good solar cells were made using the copper paste back contacts demonstrating that the electrodes are not the limiting factors in efficiency.

  15. Insights into the fluoride-resistant regulation mechanism of Acidithiobacillus ferrooxidans ATCC 23270 based on whole genome microarrays.

    PubMed

    Ma, Liyuan; Li, Qian; Shen, Li; Feng, Xue; Xiao, Yunhua; Tao, Jiemeng; Liang, Yili; Yin, Huaqun; Liu, Xueduan

    2016-10-01

    Acidophilic microorganisms involved in uranium bioleaching are usually suppressed by dissolved fluoride ions, eventually leading to reduced leaching efficiency. However, little is known about the regulation mechanisms of microbial resistance to fluoride. In this study, the resistance of Acidithiobacillus ferrooxidans ATCC 23270 to fluoride was investigated by detecting bacterial growth fluctuations and ferrous or sulfur oxidation. To explore the regulation mechanism, a whole genome microarray was used to profile the genome-wide expression. The fluoride tolerance of A. ferrooxidans cultured in the presence of FeSO4 was better than that cultured with the S(0) substrate. The differentially expressed gene categories closely related to fluoride tolerance included those involved in energy metabolism, cellular processes, protein synthesis, transport, the cell envelope, and binding proteins. This study highlights that the cellular ferrous oxidation ability was enhanced at the lower fluoride concentrations. An overview of the cellular regulation mechanisms of extremophiles to fluoride resistance is discussed.

  16. Uranium Industry Annual, 1992

    SciTech Connect

    Not Available

    1993-10-28

    The Uranium Industry Annual provides current statistical data on the US uranium industry for the Congress, Federal and State agencies, the uranium and electric utility industries, and the public. The feature article, ``Decommissioning of US Conventional Uranium Production Centers,`` is included. Data on uranium raw materials activities including exploration activities and expenditures, resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities including domestic uranium purchases, commitments by utilities, procurement arrangements, uranium imports under purchase contracts and exports, deliveries to enrichment suppliers, inventories, secondary market activities, utility market requirements, and uranium for sale by domestic suppliers are presented in Chapter 2.

  17. The water fluoridation debate.

    PubMed

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

    2011-01-01

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

  18. Fluoride and Oral Health.

    PubMed

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

    2016-06-01

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

  19. PRODUCTION OF URANIUM MONOCARBIDE

    DOEpatents

    Powers, R.M.

    1962-07-24

    A method of making essentially stoichiometric uranium monocarbide by pelletizing a mixture of uranium tetrafluoride, silicon, and carbon and reacting the mixture at a temperature of approximately 1500 to 1700 deg C until the reaction goes to completion, forming uranium monocarbide powder and volatile silicon tetrafluoride, is described. The powder is then melted to produce uranium monocarbide in massive form. (AEC)

  20. PRODUCTION OF URANIUM TETRACHLORIDE

    DOEpatents

    Calkins, V.P.

    1958-12-16

    A process is descrlbed for the production of uranium tetrachloride by contacting uranlum values such as uranium hexafluoride, uranlum tetrafluoride, or uranium oxides with either aluminum chloride, boron chloride, or sodium alumlnum chloride under substantially anhydrous condltlons at such a temperature and pressure that the chlorldes are maintained in the molten form and until the uranium values are completely converted to uranlum tetrachloride.

  1. Remineralisation and arresting caries in children with topical fluorides.

    PubMed

    Gugnani, Neeraj; Gugnani, Shalini

    2017-06-23

    Data sourcesThe Cochrane Library, PubMed, Embase and the ISI Web of Science.Study selectionEnglish language clinical trials in children with outcome measures including the remineralisation or arresting effect of caries by professional fluoride treatment were considered.Data extraction and synthesisTwo reviewers screened the studies and assessed risk of bias. Random effects meta-analysis was conducted.ResultsSeventeen studies were included, ten focused on remineralisation, seven on arresting carious lesions. Meta-analysis of four studies using 5% fluoride varnish found a 63.6% (95% CI; 36.0% - 91.2%) remineralisation of early enamel caries. For five studies using 38% silver diamine fluoride solution meta-analysis found 65.9% (95% CI; 41.2% - 90.7%) of caries arrested.ConclusionsProfessionally applied 5% sodium fluoride varnish shows the capability to remineralise early enamel caries in children. Silver diamine fluoride solution at 38% is effective in arresting active dentine caries. Because the number of clinical trials that studied the arresting effect of dental caries is limited, more clinical trials should be performed.

  2. URANIUM EXTRACTION

    DOEpatents

    Harrington, C.D.; Opie, J.V.

    1958-07-01

    The recovery of uranium values from uranium ore such as pitchblende is described. The ore is first dissolved in nitric acid, and a water soluble nitrate is added as a salting out agent. The resulting feed solution is then contacted with diethyl ether, whereby the bulk of the uranyl nitrate and a portion of the impurities are taken up by the ether. This acid ether extract is then separated from the aqueous raffinate, and contacted with water causing back extractioa of the uranyl nitrate and impurities into the water to form a crude liquor. After separation from the ether extract, this crude liquor is heated to about 118 deg C to obtain molten uranyl nitrate hexahydratc. After being slightly cooled the uranyl nitrate hexahydrate is contacted with acid free diethyl ether whereby the bulk of the uranyl nitrate is dissolved into the ethcr to form a neutral ether solution while most of the impurities remain in the aqueous waste. After separation from the aqueous waste, the resultant ether solution is washed with about l0% of its volume of water to free it of any dissolved impurities and is then contacted with at least one half its volume of water whereby the uranyl nitrate is extracted into the water to form an aqueous product solution.

  3. Magnetic separation of uranium from waste materials

    SciTech Connect

    Hoegler, J.M.

    1987-01-01

    Criteria were developed for selection of candidate wastes for testing magnetic separation of uranium and/or other paramagnetic materials. A survey of Department of Energy (DOE) hazardous wastes was conducted to determine good candidates for bench-scale magnetic separation tests. Representatives of 21 DOE sites were contacted, and materials were identified as potential candidates for magnetic separation. To date, seven samples have been obtained and tested for separability of uranium with a bench-scale magnetic assaying device. The samples tested have been obtained from the K-1401B and K-1401C ponds in Oak Ridge, Tennessee; from waste piles in Maywood, New Jersey; from North and South Ponds in Richland, Washington; and from magnesium fluoride drums in Fernald, Ohio. The magnetic device utilized in these tests can be used in a deflective mode with dry particulate samples or a matrix-gradient mode with either dry particulate or liquid-suspended materials. Uranium separation from magnesium fluoride has shown exceptionally good performance in both wet and dry systems and could be an important application of the technology. 13 figs., 6 tabs.

  4. DECONTAMINATION OF URANIUM

    DOEpatents

    Feder, H.M.; Chellew, N.R.

    1958-02-01

    This patent deals with the separation of rare earth and other fission products from neutron bombarded uranium. This is accomplished by melting the uranium in contact with either thorium oxide, maguesium oxide, alumnum oxide, beryllium oxide, or uranium dioxide. The melting is preferably carried out at from 1150 deg to 1400 deg C in an inert atmosphere, such as argon or helium. During this treatment a scale of uranium dioxide forms on the uranium whtch contains most of the fission products.

  5. Influence of anionic species on uranium separation from acid mine water using strong base resins.

    PubMed

    Ladeira, Ana Claudia Queiroz; Gonçalves, Carlos Renato

    2007-09-30

    The presence of uranium and other elements in high concentrations in acid mine drainage at Poços de Caldas Uranium Mine (Brazil) is a matter of concern. The acid water pH is around 2.7, the uranium concentration is in the range of 6-14 mg L(-1), sulfate concentration near 1400 mg L(-1), fluoride 140 mg L(-1) and iron 180 mg L(-1). In this solution, where sulfate is present in elevated concentrations, uranium is basically in the form of UO(2)(SO(4))(3)(4-). This study investigated the separation of uranium from the other anions present in the acid water under batch and column mode using ion exchange technique. The pH studied was 2.7 and 3.9. Two strong base anionic resins were tested. The influence of ions, commonly found in acid waters like sulfate and fluoride, on ion exchange process was also assessed. Equilibrium studies were carried out to determine the maximum adsorption capacities of the resins. The resins showed a significant capacity for uranium uptake which varied from 66 to 108 mg g(-1) for IRA 910U and 53 to 79 mg g(-1) for Dowex A. The results also showed that SO(4)(2-) is the most interfering ion and it had a deleterious effect on the recovery in the pH range studied. Fluoride did not affect uranium removal.

  6. Fluoride in dental erosion.

    PubMed

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

    2011-01-01

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

  7. Fluorides and non-fluoride remineralization systems.

    PubMed

    Amaechi, Bennett T; van Loveren, Cor

    2013-01-01

    Caries develops when the equilibrium between de- and remineralization is unbalanced favoring demineralization. De- and remineralization occur depending on the degree of saturation of the interstitial fluids with respect to the tooth mineral. This equilibrium is positively influenced when fluoride, calcium and phosphate ions are added favoring remineralization. In addition, when fluoride is present, it will be incorporated into the newly formed mineral which is then less soluble. Toothpastes may contain fluoride and calcium ions separately or together in various compounds (remineralization systems) and may therefore reduce demineralization and promote remineralization. Formulating all these compounds in one paste may be challenging due to possible premature calcium-fluoride interactions and the low solubility of CaF2. There is a large amount of clinical evidence supporting the potent caries preventive effect of fluoride toothpastes indisputably. The amount of clinical evidence of the effectiveness of the other remineralization systems is far less convincing. Evidence is lacking for head to head comparisons of the various remineralization systems. Copyright © 2013 S. Karger AG, Basel.

  8. URANIUM DECONTAMINATION

    DOEpatents

    Buckingham, J.S.; Carroll, J.L.

    1959-12-22

    A process is described for reducing the extractability of ruthenium, zirconium, and niobium values into hexone contained in an aqueous nitric acid uranium-containing solution. The solution is made acid-deficient, heated to between 55 and 70 deg C, and at that temperature a water-soluble inorganic thiosulfate is added. By this, a precipitate is formed which carries the bulk of the ruthenium, and the remainder of the ruthenium as well as the zirconium and niobium are converted to a hexone-nonextractable form. The rutheniumcontaining precipitate can either be removed from the solu tion or it can be dissolved as a hexone-non-extractable compound by the addition of sodium dichromate prior to hexone extraction.

  9. PRODUCTION OF THORIUM FLUORIDE

    DOEpatents

    Zachariasen, W.H.

    1959-08-11

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

  10. Indium fluoride glass fibers

    NASA Astrophysics Data System (ADS)

    Saad, Mohammed

    2012-03-01

    Fluoride glasses are the only material that transmit light from ultraviolet to mid-infrared and can be drawn into industrial optical fibers. The mechanical and optical properties of new indium fluoride glass fibers have been investigated. Multimode fiber 190 microns, has very high mechanical strength greater than 100 kpsi and optical loss as low as 45 dB/km between 2 and 4 microns. Unlike chalcogenide glass fibers, indium fluoride fiber has a wide transmission window from 0.3 to 5.5 microns without any absorption peak. Indium fluoride glass fibers are the technology of choice for all application requiring transmission up to 5 micron such as infrared contour measure (IRCM) and chemical sensing. Furthermore, Indium fluoride glasses have low phonon energy and can be heavily doped and co-doped whit rare-earth elements. Therefore they are very promising candidates for infrared fiber lasers.

  11. Uranium industry annual 1994

    SciTech Connect

    1995-07-05

    The Uranium Industry Annual 1994 (UIA 1994) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing during that survey year. The UIA 1994 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. It contains data for the 10-year period 1985 through 1994 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data collected on the ``Uranium Industry Annual Survey`` (UIAS) provide a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1994, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. A feature article, ``Comparison of Uranium Mill Tailings Reclamation in the United States and Canada,`` is included in the UIA 1994. Data on uranium raw materials activities including exploration activities and expenditures, EIA-estimated resources and reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities, including purchases of uranium and enrichment services, and uranium inventories, enrichment feed deliveries (actual and projected), and unfilled market requirements are shown in Chapter 2.

  12. Uranium industry annual 1998

    SciTech Connect

    1999-04-22

    The Uranium Industry Annual 1998 (UIA 1998) provides current statistical data on the US uranium industry`s activities relating to uranium raw materials and uranium marketing. It contains data for the period 1989 through 2008 as collected on the Form EIA-858, ``Uranium Industry Annual Survey.`` Data provides a comprehensive statistical characterization of the industry`s activities for the survey year and also include some information about industry`s plans and commitments for the near-term future. Data on uranium raw materials activities for 1989 through 1998, including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment, are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2008, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, and uranium inventories, are shown in Chapter 2. The methodology used in the 1998 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. The Form EIA-858 ``Uranium Industry Annual Survey`` is shown in Appendix D. For the readers convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix E along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 24 figs., 56 tabs.

  13. Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Khaydarov, R. R.; Khaydarov, R. A.; Estrin, Y.; Evgrafova, S.; Scheper, T.; Endres, C.; Cho, S. Y.

    The bactericidal effect of silver nanoparticles obtained by a novel electrochemical method on Escherichia coli, Staphylococcus aureus, Aspergillus niger and Penicillium phoeniceum cultures has been studied. The tests conducted have demonstrated that synthesized silver nanoparticles — when added to water paints or cotton fabrics — show a pronounced antibacterial/antifungal effect. It was shown that smaller silver nanoparticles have a greater antibacterial/antifungal efficacy. The paper also provides a review of scientific literature with regard to recent developments in the field of toxicity of silver nanoparticles and its effect on environment and human health.

  14. Evaluation of a laser-induced fluorescence system for uranium analysis

    SciTech Connect

    White, L.E.

    1980-05-01

    A laser-induced fluorescence method for total uranium analysis of industrial process waters, waste waters, and leachates has been evaluated as a possible alternative for the normal, sodium fluoride and lithium fluoride, flame-fusion fluorescence method currently employed. Since the lower reporting limit of the laser fluorometer is on the order of 0.05 ..mu..g/L, samples for normal analysis can usually be diluted from 100 to 1000 fold which virtually eliminates interferences from quenching substances. Also, since the uranium determination is done in aqueous solution, laser-induced fluorescence entirely eliminates the need for organic extraction and the subsequent fusion process.

  15. PRODUCTION OF PURIFIED URANIUM

    DOEpatents

    Burris, L. Jr.; Knighton, J.B.; Feder, H.M.

    1960-01-26

    A pyrometallurgical method for processing nuclear reactor fuel elements containing uranium and fission products and for reducing uranium compound; to metallic uranium is reported. If the material proccssed is essentially metallic uranium, it is dissolved in zinc, the sulution is cooled to crystallize UZn/sub 9/ , and the UZn/sub 9/ is distilled to obtain uranium free of fission products. If the material processed is a uranium compound, the sollvent is an alloy of zinc and magnesium and the remaining steps are the same.

  16. Uranophane at Silver Cliff mine, Lusk, Wyoming

    USGS Publications Warehouse

    Wilmarth, Verl R.; Johnson, D.H.

    1954-01-01

    The uranium deposit at the Silver Cliff mine near Lusk, Wyo., consists primarily of uranophane which occurs as fracture fillings and small replacement pockets in faulted and fractured calcareous sandstone of Cambrian (?) age. The country rock in the vicinity of the mine is schist of pre-Cambrian age intruded by pegmatite dikes and is unconformably overlain by almost horizontal sandstone of Cambrian(?) age. The mine is on the southern end of the Lusk Dome, a local structure probably related to the Hartville uplift. In the immediate vicinity of the mine, the dome is cut by the Silver Cliff fault, a north-trending high-angle reverse fault about 1,200 feet in length with a stratigraphic throw of 70 feet. Uranophane, metatorbernite, pitchblende, calcite, native silver, native copper, chalcocite, azurite, malachite, chrysocolla, and cuprite have been deposited in fractured sandstone. The fault was probably mineralized throughout its length, but because of erosion, the mineralized zone is discontinuous. The principal ore body is about 800 feet long. The width and depth of the mineralized zone are not accurately known but are at least 20 feet and 60 feet respectively. The uranium content of material sampled in the mine ranges from 0.001 to 0.23 percent uranium, whereas dump samples range from 0.076 to 3.39 percent uranium.

  17. Resin-modified glass ionomer cements: fluoride release and influence on Streptococcus mutans growth.

    PubMed

    Friedl, K H; Schmalz, G; Hiller, K A; Shams, M

    1997-02-01

    The aims of the present study were to measure the fluoride release of 1 glass ionomer cement, 1 cermet, 3 resin-modified glass ionomer cements and 1 compomer, and to determine the influence of each material on bacterial growth. Test specimens were eluted in saline for 180 days. Every 2 days, the specimens were transferred into fresh saline and the fluoride content of the solution was measured. Furthermore, 48-h, 14-d, 90-d, and 180-d eluates were inoculated with Streptococcus mutans and bacterial growth was recorded nephelometrically. Fluoride release dropped significantly over time for each material with values between 6.2 (Ketac-Silver) and 29.3 (Photac-Fil) ppm after 48 h to values between 0.6 (Ketac-Silver) and 1.7 (Ketac-Fil, Vitremer) ppm after 180 days. Each material reduced bacterial growth at each time of examination, but the effect decreased significantly over time with a maximum growth of 71.7% (Ketac-Fil) to 85.6% (Ketac-Silver) after 48 h and 94.7 (Vitremer) to 99.0% (Ketac-Silver) after 180 days (growth control = 100%). Both Ketac-Silver and Dyract showed a significantly lower inhibiting effect on bacterial growth than the other materials. The tested materials showed a good correlation between fluoride release and influence on bacterial growth. However, both effects dropped dramatically over the 180-days period.

  18. Radiolytic Effects on Fluoride Impurities in a U{sub 3}O{sub 8} Matrix

    SciTech Connect

    Icenhour, A.S.

    2000-05-01

    The safe handling and storage of radioactive materials require an understanding of the effects of radiolysis on those materials. Radiolysis may result in the production of gases (e.g., corrosives) or pressures that are deleterious to storage containers. A study has been performed to address these concerns as they relate to the radiolysis of residual fluoride compounds in uranium oxides.

  19. Uranium provinces of North America; their definition, distribution, and models

    USGS Publications Warehouse

    Finch, Warren Irvin

    1996-01-01

    Uranium resources in North America are principally in unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits. Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate and unconformity-related deposits are, respectively, in the Blind River?Elliot Lake (BRELUP) and the Athabasca Basin (ABUP) Uranium Provinces in Canada. Sandstone uranium deposits are of two principal subtypes, tabular and roll-front. Tabular sandstone uranium deposits are mainly in upper Paleozoic and Mesozoic rocks in the Colorado Plateau Uranium Province (CPUP). Roll-front sandstone uranium deposits are in Tertiary rocks of the Rocky Mountain and Intermontane Basins Uranium Province (RMIBUP), and in a narrow belt of Tertiary rocks that form the Gulf Coastal Uranium Province (GCUP) in south Texas and adjacent Mexico. Volcanic uranium deposits are concentrated in the Basin and Range Uranium Province (BRUP) stretching from the McDermitt caldera at the Oregon-Nevada border through the Marysvale district of Utah and Date Creek Basin in Arizona and south into the Sierra de Pe?a Blanca District, Chihuahua, Mexico. Uraniferous phosphorite occurs in Tertiary sediments in Florida, Georgia, and North and South Carolina and in the Lower Permian Phosphoria Formation in Idaho and adjacent States, but only in Florida has economic recovery been successful. The Florida Phosphorite Uranium Province (FPUP) has yielded large quantities of uranium as a byproduct of the production of phosphoric acid fertilizer. Economically recoverable quantities of copper, gold, molybdenum, nickel, silver, thorium, and vanadium occur with the uranium deposits in some provinces. Many major epochs of uranium mineralization occurred in North America. In the BRELUP, uranium minerals were concentrated in placers during the Early Proterozoic (2,500?2,250 Ma). In the ABUP, the unconformity-related deposits were most likely formed

  20. Uranium provinces of North America; their definition, distribution, and models

    USGS Publications Warehouse

    Finch, Warren Irvin

    1996-01-01

    Uranium resources in North America are principally in unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits. Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate and unconformity-related deposits are, respectively, in the Blind River–Elliot Lake (BRELUP) and the Athabasca Basin (ABUP) Uranium Provinces in Canada. Sandstone uranium deposits are of two principal subtypes, tabular and roll-front. Tabular sandstone uranium deposits are mainly in upper Paleozoic and Mesozoic rocks in the Colorado Plateau Uranium Province (CPUP). Roll-front sandstone uranium deposits are in Tertiary rocks of the Rocky Mountain and Intermontane Basins Uranium Province (RMIBUP), and in a narrow belt of Tertiary rocks that form the Gulf Coastal Uranium Province (GCUP) in south Texas and adjacent Mexico. Volcanic uranium deposits are concentrated in the Basin and Range Uranium Province (BRUP) stretching from the McDermitt caldera at the Oregon-Nevada border through the Marysvale district of Utah and Date Creek Basin in Arizona and south into the Sierra de Peña Blanca District, Chihuahua, Mexico. Uraniferous phosphorite occurs in Tertiary sediments in Florida, Georgia, and North and South Carolina and in the Lower Permian Phosphoria Formation in Idaho and adjacent States, but only in Florida has economic recovery been successful. The Florida Phosphorite Uranium Province (FPUP) has yielded large quantities of uranium as a byproduct of the production of phosphoric acid fertilizer. Economically recoverable quantities of copper, gold, molybdenum, nickel, silver, thorium, and vanadium occur with the uranium deposits in some provinces.Many major epochs of uranium mineralization occurred in North America. In the BRELUP, uranium minerals were concentrated in placers during the Early Proterozoic (2,500–2,250 Ma). In the ABUP, the unconformity-related deposits were most likely

  1. METHOD FOR PURIFYING URANIUM

    DOEpatents

    Knighton, J.B.; Feder, H.M.

    1960-04-26

    A process is given for purifying a uranium-base nuclear material. The nuclear material is dissolved in zinc or a zinc-magnesium alloy and the concentration of magnesium is increased until uranium precipitates.

  2. NICKEL COATED URANIUM ARTICLE

    DOEpatents

    Gray, A.G.

    1958-10-01

    Nickel coatings on uranium and various methods of obtaining such coatings are described. Specifically disclosed are such nickel or nickel alloy layers as barriers between uranium and aluminum- silicon, chromium, or copper coatings.

  3. Silver-catalyzed late-stage fluorination.

    PubMed

    Tang, Pingping; Furuya, Takeru; Ritter, Tobias

    2010-09-01

    Carbon-fluorine bond formation by transition metal catalysis is difficult, and only a few methods for the synthesis of aryl fluorides have been developed. All reported transition-metal-catalyzed fluorination reactions for the synthesis of functionalized arenes are based on palladium. Here we present silver catalysis for carbon-fluorine bond formation. Our report is the first example of the use of the transition metal silver to form carbon-heteroatom bonds by cross-coupling catalysis. The functional group tolerance and substrate scope presented here have not been demonstrated for any other fluorination reaction to date.

  4. PROCESS OF PURIFYING URANIUM

    DOEpatents

    Seaborg, G.T.; Orlemann, E.F.; Jensen, L.H.

    1958-12-23

    A method of obtaining substantially pure uranium from a uranium composition contaminated with light element impurities such as sodium, magnesium, beryllium, and the like is described. An acidic aqueous solution containing tetravalent uranium is treated with a soluble molybdate to form insoluble uranous molybdate which is removed. This material after washing is dissolved in concentrated nitric acid to obtaln a uranyl nitrate solution from which highly purified uranium is obtained by extraction with ether.

  5. Uranium industry annual 1995

    SciTech Connect

    1996-05-01

    The Uranium Industry Annual 1995 (UIA 1995) provides current statistical data on the U.S. uranium industry`s activities relating to uranium raw materials and uranium marketing. The UIA 1995 is prepared for use by the Congress, Federal and State agencies, the uranium and nuclear electric utility industries, and the public. It contains data for the period 1986 through 2005 as collected on the Form EIA-858, ``Uranium Industry Annual Survey``. Data collected on the ``Uranium Industry Annual Survey`` provide a comprehensive statistical characterization of the industry`s plans and commitments for the near-term future. Where aggregate data are presented in the UIA 1995, care has been taken to protect the confidentiality of company-specific information while still conveying accurate and complete statistical data. Data on uranium raw materials activities for 1986 through 1995 including exploration activities and expenditures, EIA-estimated reserves, mine production of uranium, production of uranium concentrate, and industry employment are presented in Chapter 1. Data on uranium marketing activities for 1994 through 2005, including purchases of uranium and enrichment services, enrichment feed deliveries, uranium fuel assemblies, filled and unfilled market requirements, uranium imports and exports, and uranium inventories are shown in Chapter 2. The methodology used in the 1995 survey, including data edit and analysis, is described in Appendix A. The methodologies for estimation of resources and reserves are described in Appendix B. A list of respondents to the ``Uranium Industry Annual Survey`` is provided in Appendix C. For the reader`s convenience, metric versions of selected tables from Chapters 1 and 2 are presented in Appendix D along with the standard conversion factors used. A glossary of technical terms is at the end of the report. 14 figs., 56 tabs.

  6. Fluoride ion recognition by chelating and cationic boranes.

    PubMed

    Hudnall, Todd W; Chiu, Ching-Wen; Gabbaï, François P

    2009-02-17

    Because of the ubiquity of fluoride ions and their potential toxicity at high doses, researchers would like to design receptors that selectively detect this anion. Fluoride is found in drinking water, toothpaste, and osteoporosis drugs. In addition, fluoride ions also can be detected as an indicator of uranium enrichment (via hydrolysis of UF(6)) or of the chemical warfare agent sarin, which releases the ion upon hydrolysis. However, because of its high hydration enthalpy, the fluoride anion is one of the most challenging targets for anion recognition. Among the various recognition strategies that are available, researchers have focused a great deal of attention on Lewis acidic boron compounds. These molecules typically interact with fluoride anions to form the corresponding fluoroborate species. In the case of simple triarylboranes, the fluoroborates are formed in organic solvents but not in water. To overcome this limitation, this Account examines various methods we have pursued to increase the fluoride-binding properties of boron-based receptors. We first considered the use of bifunctional boranes, which chelate the fluoride anion, such as 1,8-diborylnaphthalenes or heteronuclear 1-boryl-8-mercurio-naphthalenes. In these molecules, the neighboring Lewis acidic atoms can cooperatively interact with the anionic guest. Although the fluoride binding constants of the bifunctional compounds exceed those of neutral monofunctional boranes by several orders of magnitude, the incompatibility of these systems with aqueous media limits their utility. More recently, we have examined simple triarylboranes whose ligands are decorated by cationic ammonium or phosphonium groups. These cationic groups increase the electrophilic character of these boranes, and unlike their neutral analogs, they are able to complex fluoride in aqueous media. We have also considered cationic boranes, which form chelate complexes with fluoride anions. Our work demonstrates that Coulombic and chelate

  7. Assessment of liquid disposal originated by uranium enrichment at Aramar Experimental Center São Paulo--Brazil.

    PubMed

    Gerenutti, Marli; Gonçalves, Marcos Moisés; Rissato, Sandra Regina; de Oliveira, José Martins; dos Santos Reigota, Marco Antonio; Galhiane, Mário Sergio

    2012-07-01

    This work presents a liquid disposal monitoring originated from uranium enrichment process at Aramar Experimental Center from 1990 to 1998. Assessment of uranium, fluorides, ammoniacal nitrogen, chemical oxygen demand, and pH measurements were made in water samples and compared with results achieved in other countries, as North America and India. The liquid disposal evaluation, generated by uranium enrichment process, showed low levels, considering most parameters established by Federal and State Legislation, aiming environmental pollution control. However, uranium levels were above the limits established by Conselho Nacional do Meio Ambiente, Environment Protection Agency and mainly by the World Health Organization.

  8. PRODUCTION OF URANIUM TETRAFLUORIDE

    DOEpatents

    Shaw, W.E.; Spenceley, R.M.; Teetzel, F.M.

    1959-08-01

    A method is presented for producing uranium tetrafluoride from the gaseous hexafluoride by feeding the hexafluoride into a high temperature zone obtained by the recombination of molecularly dissociated hydrogen. The molal ratio of hydrogen to uranium hexnfluoride is preferably about 3 to 1. Uranium tetrafluoride is obtained in a finely divided, anhydrous state.

  9. How Does Fluoride Work?

    MedlinePlus

    ... Fluoride is a natural element found in the earth's crust as well as in water and air. ... Activity: Teeth What Are Dentures? Contact Us Print Resources Send to a Friend Permissions Guidelines About KidsHealth ...

  10. Fluoridation: strategies for success.

    PubMed Central

    Isman, R

    1981-01-01

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

  11. Fluoride in diet

    MedlinePlus

    ... broken through the gums have changes in the enamel that covers the teeth. Faint white lines or ... regarding fluoride intake from reconstituted infant formula and enamel fluorosis: a report of the American Dental Association ...

  12. Fluoridation: strategies for success.

    PubMed

    Isman, R

    1981-07-01

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

  13. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  14. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  15. PROCESS OF RECOVERING URANIUM

    DOEpatents

    Carter, J.M.; Larson, C.E.

    1958-10-01

    A process is presented for recovering uranium values from calutron deposits. The process consists in treating such deposits to produce an oxidlzed acidic solution containing uranium together with the following imparities: Cu, Fe, Cr, Ni, Mn, Zn. The uranium is recovered from such an impurity-bearing solution by adjusting the pH of the solution to the range 1.5 to 3.0 and then treating the solution with hydrogen peroxide. This results in the precipitation of uranium peroxide which is substantially free of the metal impurities in the solution. The peroxide precipitate is then separated from the solution, washed, and calcined to produce uranium trioxide.

  16. URANIUM SEPARATION PROCESS

    DOEpatents

    Hyde, E.K.; Katzin, L.I.; Wolf, M.J.

    1959-07-14

    The separation of uranium from a mixture of uranium and thorium by organic solvent extraction from an aqueous solution is described. The uranium is separrted from an aqueous mixture of uranium and thorium nitrates 3 N in nitric acid and containing salting out agents such as ammonium nitrate, so as to bring ihe total nitrate ion concentration to a maximum of about 8 N by contacting the mixture with an immiscible aliphatic oxygen containing organic solvent such as diethyl carbinol, hexone, n-amyl acetate and the like. The uranium values may be recovered from the organic phase by back extraction with water.

  17. URANIUM RECOVERY PROCESS

    DOEpatents

    Yeager, J.H.

    1958-08-12

    In the prior art processing of uranium ores, the ore is flrst digested with nitric acid and filtered, and the uranium values are then extracted tom the filtrate by contacting with an organic solvent. The insoluble residue has been processed separately in order to recover any uranium which it might contain. The improvement consists in contacting a slurry, composed of both solution and residue, with the organic solvent prior to filtration. Tbe result is that uranium values contained in the residue are extracted along with the uranium values contained th the solution in one step.

  18. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed. The...

  19. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed. The...

  20. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed. The...

  1. Fluoride content of infant foods.

    PubMed

    Steele, Jaime L; Martinez-Mier, E Angeles; Sanders, Brian J; Jones, James E; Jackson, Richard D; Soto-Rojas, Armando E; Tomlin, Angela M; Eckert, George J

    2014-01-01

    Excessive fluoride consumption during the first 2 years of life is associated with an increased risk of dental fluorosis. Estimates of fluoride intake from various sources may aid in determining a child's risk for developing fluorosis. This study sought to assess the fluoride content of commercially available foods for infants, and to guide dentists who are advising parents of young children about fluoride intake. Three samples each of 20 different foods (including fruits and vegetables, as well as chicken, turkey, beef/ham, and vegetarian dinners) from 3 manufacturers were analyzed (in duplicate) for their fluoride content. Among the 360 samples tested, fluoride concentration ranged from 0.007-4.13 μg fluoride/g food. All foods tested had detectable amounts of fluoride. Chicken products had the highest mean levels of fluoride, followed by turkey products. Consuming >1 serving per day of the high fluoride concentration products in this study would place children over the recommended daily fluoride intake. Fluoride from infant foods should be taken into account when determining total daily fluoride intake.

  2. Possible uranium mineralization, Mineral Mountains, Utah

    USGS Publications Warehouse

    Miller, W. Roger; McHugh, John B.; Ficklin, Walter H.

    1979-01-01

    The Mineral Mountains block in west-central Utah is a horst whose core stands structurally high relative to all nearby basin-and-range fault blocks. Rocks of the Mineral Mountains range from Precambrian to Quaternary in age, but mostly consist of Tertiary granitic rocks. The range lies with the Wah Wah-Tusher mineral belt. Lead, silver, gold, and tungsten have been mined commercially. During a geochemical survey conducted in the summer of 1978, 30 water samples and 29 stream-sediment samples were collected from the Mineral Mountains area. The interpretation of simple plots of uranium concentrations and the results of a Q-mode factor analysis indicate that potential exists for uranium mineral deposits within the Mineral Mountains. The most favorable areas are in the granitic pluton near its contacts with sedimentary and metamorphic rocks. The most likely source of the uranium anomalies is uraninite-bearing epigenic veins along faults and fractures within the pluton. Three hypothetical models are proposed to account for the uranium mineralization.

  3. Russell-Silver syndrome

    MedlinePlus

    Silver-Russell syndrome; Silver syndrome; RSS; Russell-Silver syndrome ... Organization for Rare Disorders -- rarediseases.org/rare-diseases/russell-silver-syndrome NIH/NLM Genetics Home Reference -- ghr. ...

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

    PubMed

    Nordbö, H; Eriksen, H M

    1976-11-01

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

  5. Disinfection of Spacecraft Potable Water Systems by Passivation with Ionic Silver

    NASA Technical Reports Server (NTRS)

    Birmele, Michele N.; McCoy, LaShelle e.; Roberts, Michael S.

    2011-01-01

    Microbial growth is common on wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and physical disinfection methods. Advanced control technologies are needed to limit microorganisms and increase the reliability of life support systems required for long-duration human missions. Silver ions and compounds are widely used as antimicrobial agents for medical applications and continue to be used as a residual biocide in some spacecraft water systems. The National Aeronautics and Space Administration (NASA) has identified silver fluoride for use in the potable water system on the next generation spacecraft. Due to ionic interactions between silver fluoride in solution and wetted metallic surfaces, ionic silver is rapidly depleted from solution and loses its antimicrobial efficacy over time. This report describes research to prolong the antimicrobial efficacy of ionic silver by maintaining its solubility. Three types of metal coupons (lnconel 718, Stainless Steel 316, and Titanium 6AI-4V) used in spacecraft potable water systems were exposed to either a continuous flow of water amended with 0.4 mg/L ionic silver fluoride or to a static, pre-treatment passivation in 50 mg/L ionic silver fluoride with or without a surface oxidation pre-treatment. Coupons were then challenged in a high-shear, CDC bioreactor (BioSurface Technologies) by exposure to six bacteria previously isolated from spacecraft potable water systems. Continuous exposure to 0.4 mg/L ionic silver over the course of 24 hours during the flow phase resulted in a >7-log reduction. The residual effect of a 24-hour passivation treatment in 50 mg/L of ionic silver resulted in a >3-log reduction, whereas a two-week treatment resulted in a >4-log reduction. Results indicate that 0.4 mg/L ionic silver is an effective biocide against many bacteria and that a prepassivation of metal surfaces with silver can provide additional microbial control.

  6. Welding of uranium and uranium alloys

    SciTech Connect

    Mara, G.L.; Murphy, J.L.

    1982-03-26

    The major reported work on joining uranium comes from the USA, Great Britain, France and the USSR. The driving force for producing this technology base stems from the uses of uranium as a nuclear fuel for energy production, compact structures requiring high density, projectiles, radiation shielding, and nuclear weapons. This review examines the state-of-the-art of this technology and presents current welding process and parameter information. The welding metallurgy of uranium and the influence of microstructure on mechanical properties is developed for a number of the more commonly used welding processes.

  7. Uranium hexafluoride public risk

    SciTech Connect

    Fisher, D.R.; Hui, T.E.; Yurconic, M.; Johnson, J.R.

    1994-08-01

    The limiting value for uranium toxicity in a human being should be based on the concentration of uranium (U) in the kidneys. The threshold for nephrotoxicity appears to lie very near 3 {mu}g U per gram kidney tissue. There does not appear to be strong scientific support for any other improved estimate, either higher or lower than this, of the threshold for uranium nephrotoxicity in a human being. The value 3 {mu}g U per gram kidney is the concentration that results from a single intake of about 30 mg soluble uranium by inhalation (assuming the metabolism of a standard person). The concentration of uranium continues to increase in the kidneys after long-term, continuous (or chronic) exposure. After chronic intakes of soluble uranium by workers at the rate of 10 mg U per week, the concentration of uranium in the kidneys approaches and may even exceed the nephrotoxic limit of 3 {mu}g U per gram kidney tissue. Precise values of the kidney concentration depend on the biokinetic model and model parameters assumed for such a calculation. Since it is possible for the concentration of uranium in the kidneys to exceed 3 {mu}g per gram tissue at an intake rate of 10 mg U per week over long periods of time, we believe that the kidneys are protected from injury when intakes of soluble uranium at the rate of 10 mg U per week do not continue for more than two consecutive weeks. For long-term, continuous occupational exposure to low-level, soluble uranium, we recommend a reduced weekly intake limit of 5 mg uranium to prevent nephrotoxicity in workers. Our analysis shows that the nephrotoxic limit of 3 {mu}g U per gram kidney tissues is not exceeded after long-term, continuous uranium intake at the intake rate of 5 mg soluble uranium per week.

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

    PubMed

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

    2017-01-20

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

  9. Bioremediation of uranium contamination with enzymatic uranium reduction

    USGS Publications Warehouse

    Lovley, D.R.; Phillips, E.J.P.

    1992-01-01

    Enzymatic uranium reduction by Desulfovibrio desulfuricans readily removed uranium from solution in a batch system or when D. desulfuricans was separated from the bulk of the uranium-containing water by a semipermeable membrane. Uranium reduction continued at concentrations as high as 24 mM. Of a variety of potentially inhibiting anions and metals evaluated, only high concentrations of copper inhibited uranium reduction. Freeze-dried cells, stored aerobically, reduced uranium as fast as fresh cells. D. desulfuricans reduced uranium in pH 4 and pH 7.4 mine drainage waters and in uraniumcontaining groundwaters from a contaminated Department of Energy site. Enzymatic uranium reduction has several potential advantages over other bioprocessing techniques for uranium removal, the most important of which are as follows: the ability to precipitate uranium that is in the form of a uranyl carbonate complex; high capacity for uranium removal per cell; the formation of a compact, relatively pure, uranium precipitate.

  10. The isotopic ratio measurement of uranium in the form of hydrolyzed uranium hexafluoride by inductively coupled plasma multiple collector mass spectrometry

    SciTech Connect

    Walder, A.J.; Hodgson, T.

    1995-12-31

    An inductively coupled plasma-multiple collector-mass spectrometer (ICP-MC-MS) has been used to measure the isotopic composition of uranium in three solutions of uranium hexafluoride. The {sup 235}U:{sup 238}U ratio of each sample solution ranged from approximately 0.007 to 0.03 to 1.0. The measurements are linear over this range and the precision and accuracy are comparable, if not superior, to that obtained by thermal ionization mass spectrometry (TIMS). However, acceptable isotopic ratio measurement of uranium hexafluoride solutions is not possible by TIMS because the presence of fluoride ions severely limits analytical precision. Hence, the fluoride must be removed prior to analysis. This necessitates a chemical purification stage which adds both time and expense to the measurement process. This study reports direct, high precision, accurate uranium isotope ratio measurements on solutions of uranium hexafluoride. The instrumental time required for the analysis of 15 uranium samples with the ICP-MC-MS totals 135 min. This compares with an estimated time requirement of 600 min by TIMS and a time of 900 min by UF{sub 6} gas mass spectrometry.

  11. Fluoride-containing restorative materials.

    PubMed

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

    2006-02-01

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

  12. Uranium purchases report 1992

    SciTech Connect

    Not Available

    1993-08-19

    Data reported by domestic nuclear utility companies in their responses to the 1991 and 1992 ``Uranium Industry Annual Survey,`` Form EIA-858, Schedule B ``Uranium Marketing Activities,are provided in response to the requirements in the Energy Policy Act 1992. Data on utility uranium purchases and imports are shown on Table 1. Utility enrichment feed deliveries and secondary market acquisitions of uranium equivalent of US DOE separative work units are shown on Table 2. Appendix A contains a listing of firms that sold uranium to US utilities during 1992 under new domestic purchase contracts. Appendix B contains a similar listing of firms that sold uranium to US utilities during 1992 under new import purchase contracts. Appendix C contains an explanation of Form EIA-858 survey methodologies with emphasis on the processing of Schedule B data.

  13. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

    1995-06-06

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

  14. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

    1995-01-01

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

  15. Estimation of uranium in columbite-tantalite samples: A method for sample solution preparation for fluorimetric estimation.

    PubMed

    Balaji, B K; Premadas, A; Ramanaiah, G V

    1984-10-01

    A method has been developed for obtaining a clear solution of columbite-tantalite samples in nitric acid medium before the fluorimetric estimation of uranium. Ammonium hydrogen fluoride is used to keep tantalum, niobium and titanium dissolved in the acid medium. The excess of fluoride is complexed with boric acid. The method has been successfully applied to a number of synthetic and natural columbite-tantalite samples.

  16. Fluoride release from fluoride varnishes under acidic conditions.

    PubMed

    Lippert, F

    2014-01-01

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

  17. Preparation of uranium compounds

    DOEpatents

    Kiplinger, Jaqueline L; Montreal, Marisa J; Thomson, Robert K; Cantat, Thibault; Travia, Nicholas E

    2013-02-19

    UI.sub.3(1,4-dioxane).sub.1.5 and UI.sub.4(1,4-dioxane).sub.2, were synthesized in high yield by reacting turnings of elemental uranium with iodine dissolved in 1,4-dioxane under mild conditions. These molecular compounds of uranium are thermally stable and excellent precursor materials for synthesizing other molecular compounds of uranium including alkoxide, amide, organometallic, and halide compounds.

  18. Metals fact sheet - uranium

    SciTech Connect

    1996-04-01

    About 147 million pounds of this radioactive element are consumed annually by the worldwide nuclear power and weapons industries, as well as in the manufacture of ceramics and metal products. The heaviest naturally occurring element, uranium is typically found in intrusive granites, igneous and metamorphic veins, tabular sedimentary deposits, and unconformity-related structures. This article discusses the geology, exploitation, market, and applications of uranium and uranium ores.

  19. Nonmilitary applications of uranium

    SciTech Connect

    Polson, C.E.; Blasch, E.B.

    1981-01-01

    Uranium and its alloys should be considered for any application where weight and/or strength is required, or where weight to volume is important. There is considerable literature on uranium and its alloys. The fear of handling metallic uranium should not be a factor. It is the least hazardous of all long-lived isotopes. Sound industrial hygiene practices will provide adequate protection. In general, safety controls are similar to those required for other heavy metals.

  20. PREPARATION OF ANHYDROUS CERIUM CHLORIDE, URANIUM BROMIDE OR PLUTONIUM FLUORIDE

    DOEpatents

    Marmon, K.M.; Wichers, E.

    1961-05-01

    A process is given for preparing anhydrous metal halides and converting metal oxalates to anhydrous metal halides which are free from oxyhalides. In accordance with one embodiment of the invention, cerous chloride is prepared by passing hydrogen chloride gas over hydrated cerous oxalate below lOO deg C until no more gas is absorbed and then continuing the treatmert at higher temperatures.

  1. Antibacterial Silver

    PubMed Central

    Clement, Julia L.; Jarrett, Penelope S.

    1994-01-01

    The antibacterial activity of silver has long been known and has found a variety of applications because its toxicity to human cells is considerably lower than to bacteria. The most widely documented uses are prophylactic treatment of burns and water disinfection. However, the mechanisms by which silver kills cells are not known. Information on resistance mechanisms is apparently contradictory and even the chemistry of Ag+ in such systems is poorly understood. Silver binds to many cellular components, with membrane components probably being more important than nucleic acids. It is difficult to know whether strong binding reflects toxicity or detoxification: some sensitive bacterial strains have been reported as accumulating more silver than the corresponding resistant strain, in others the reverse apparently occurs. In several cases resistance has been shown to be plasmid mediated. The plasmids are reported as difficult to transfer, and can also be difficult to maintain, as we too have found. Attempts to find biochemical differences between resistant and sensitive strains have met with limited success: differences are subtle, such as increased cell surface hydrophobicity in a resistant Escherichia coli. Some of the problems are due to defining conditions in which resistance can be observed. Silver(I) has been shown to bind to components of cell culture media, and the presence of chloride is necessary to demonstrate resistance. The form of silver used must also be considered. This is usually water soluble AgNO3, which readily precipitates as AgCl. The clinically preferred compound is the highly insoluble silver sulfadiazine, which does not cause hypochloraemia in burns. It has been suggested that resistant bacteria are those unable to bind Ag+ more tightly than does chloride. It may be that certain forms of insoluble silver are taken up by cells, as has been found for nickel. Under our experimental conditions, silver complexed by certain ligands is more cytotoxic

  2. Antibacterial silver.

    PubMed

    Clement, J L; Jarrett, P S

    1994-01-01

    The antibacterial activity of silver has long been known and has found a variety of applications because its toxicity to human cells is considerably lower than to bacteria. The most widely documented uses are prophylactic treatment of burns and water disinfection. However, the mechanisms by which silver kills cells are not known. Information on resistance mechanisms is apparently contradictory and even the chemistry of Ag(+) in such systems is poorly understood.Silver binds to many cellular components, with membrane components probably being more important than nucleic acids. It is difficult to know whether strong binding reflects toxicity or detoxification: some sensitive bacterial strains have been reported as accumulating more silver than the corresponding resistant strain, in others the reverse apparently occurs. In several cases resistance has been shown to be plasmid mediated. The plasmids are reported as difficult to transfer, and can also be difficult to maintain, as we too have found. Attempts to find biochemical differences between resistant and sensitive strains have met with limited success: differences are subtle, such as increased cell surface hydrophobicity in a resistant Escherichia coli.Some of the problems are due to defining conditions in which resistance can be observed. Silver(I) has been shown to bind to components of cell culture media, and the presence of chloride is necessary to demonstrate resistance. The form of silver used must also be considered. This is usually water soluble AgNO(3), which readily precipitates as AgCl. The clinically preferred compound is the highly insoluble silver sulfadiazine, which does not cause hypochloraemia in burns. It has been suggested that resistant bacteria are those unable to bind Ag(+) more tightly than does chloride. It may be that certain forms of insoluble silver are taken up by cells, as has been found for nickel. Under our experimental conditions, silver complexed by certain ligands is more

  3. Intake and metabolism of fluoride.

    PubMed

    Whitford, G M

    1994-06-01

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

  4. Forensic analysis of uranium

    SciTech Connect

    Stoyer, N.J.; Moody, K.J.

    1996-10-01

    As more and more offers for illicit {open_quotes}Black Market{close_quotes} radioactive materials are found, the forensic information contained within the radioactive material itself becomes more important. Many {open_quotes}Black Market{close_quotes} offers are for uranium in various forms and enrichments. Although most are scams, some countries have actually interdicted enriched uranium. We will discuss the forensic information that can be obtained from materials containing uranium along with examples of data that has been determined from analysis of uranium samples obtained from legitimate sources.

  5. URANIUM RECOVERY PROCESS

    DOEpatents

    Kaufman, D.

    1958-04-15

    A process of recovering uranium from very low-grade ore residues is described. These low-grade uraniumcontaining hydroxide precipitates, which also contain hydrated silica and iron and aluminum hydroxides, are subjected to multiple leachings with aqueous solutions of sodium carbonate at a pH of at least 9. This leaching serves to selectively extract the uranium from the precipitate, but to leave the greater part of the silica, iron, and aluminum with the residue. The uranium is then separated from the leach liquor by the addition of an acid in sufficient amount to destroy the carbonate followed by the addition of ammonia to precipitate uranium as ammonium diuranate.

  6. Uranium Dispersion & Dosimetry Model.

    SciTech Connect

    MICHAEL,; MOMENI, H.

    2002-03-22

    The Uranium Dispersion and Dosimetry (UDAD) program provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility such as a uranium mine or mill. Only transport through the air is considered. Exposure results from inhalation, external irradiation from airborne and ground-deposited activity, and ingestion of foodstuffs. Individual dose commitments, population dose commitments, and environmental dose commitments are computed. The program was developed for application to uranium mining and milling; however, it may be applied to dispersion of any other pollutant.

  7. COATING URANIUM FROM CARBONYLS

    DOEpatents

    Gurinsky, D.H.; Storrs, S.S.

    1959-07-14

    Methods are described for making adherent corrosion resistant coatings on uranium metal. According to the invention, the uranium metal is heated in the presence of an organometallic compound such as the carbonyls of nickel, molybdenum, chromium, niobium, and tungsten at a temperature sufficient to decompose the metal carbonyl and dry plate the resultant free metal on the surface of the uranium metal body. The metal coated body is then further heated at a higher temperature to thermally diffuse the coating metal within the uranium bcdy.

  8. METHOD OF ROLLING URANIUM

    DOEpatents

    Smith, C.S.

    1959-08-01

    A method is described for rolling uranium metal at relatively low temperatures and under non-oxidizing conditions. The method involves the steps of heating the uranium to 200 deg C in an oil bath, withdrawing the uranium and permitting the oil to drain so that only a thin protective coating remains and rolling the oil coated uranium at a temperature of 200 deg C to give about a 15% reduction in thickness at each pass. The operation may be repeated to accomplish about a 90% reduction without edge cracking, checking or any appreciable increase in brittleness.

  9. URANIUM LEACHING AND RECOVERY PROCESS

    DOEpatents

    McClaine, L.A.

    1959-08-18

    A process is described for recovering uranium from carbonate leach solutions by precipitating uranium as a mixed oxidation state compound. Uranium is recovered by adding a quadrivalent uranium carbon;te solution to the carbonate solution, adjusting the pH to 13 or greater, and precipitating the uranium as a filterable mixed oxidation state compound. In the event vanadium occurs with the uranium, the vanadium is unaffected by the uranium precipitation step and remains in the carbonate solution. The uranium-free solution is electrolyzed in the cathode compartment of a mercury cathode diaphragm cell to reduce and precipitate the vanadium.

  10. Uranium deposits in Grant County, New Mexico

    USGS Publications Warehouse

    Granger, Harry C.; Bauer, Herman L.; Lovering, Tom G.; Gillerman, Elliot

    1952-01-01

    The known uranium deposits of Grant county, N. Mex., are principally in the White Signal and Black Hawk districts. Both districts are within a northwesterly-trending belt of pre-Cambrian rocks, composed chiefly of granite with included gneisses, schists, and quartzites. Younger dikes and stocks intrude the pre-Cambrian complex. The White Signal district is on the southeast flanks of the Burro Mountains; the Black Hawk district is about 18 miles northwest of the town of White Signal. In the White Signal district the seconday uranium phosphates--autunite and torbernite--occur as fracture coatings and disseminations in oxidized parts of quartz-pyrite veins, and in the adjacent mafic dikes and granites; uraniferous limonite is common locally. Most of the known uraniferous deposits are less that 50 feet in their greatest dimension. The most promising deposits in the district are on the Merry Widow and Blue Jay claims. The richest sample taken from the Merry Widow mine contained more than 2 percent uranium and a sample from the Blue Jay property contained as much as 0.11 percent; samples from the other properties were of lower grade. In the Black Hawk district pitchblende is associated with nickel, silver, and cobalt minerals in fissure veins. The most promising properties in the Black Hawk district are the Black Hawk, Alhambra, and Rose mines. No uranium analyses from this district were available in 1951. There are no known minable reserves of uranium ore in either district, although there is some vein material at the Merry Widow mine of ore grade, if a market were available in the region.

  11. Small Molecule Fluoride Toxicity Agonists

    PubMed Central

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

    2015-01-01

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

  12. Small molecule fluoride toxicity agonists.

    PubMed

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

    2015-04-23

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

  13. Uranium industry annual 1993

    SciTech Connect

    Not Available

    1994-09-01

    Uranium production in the United States has declined dramatically from a peak of 43.7 million pounds U{sub 3}O{sub 8} (16.8 thousand metric tons uranium (U)) in 1980 to 3.1 million pounds U{sub 3}O{sub 8} (1.2 thousand metric tons U) in 1993. This decline is attributed to the world uranium market experiencing oversupply and intense competition. Large inventories of uranium accumulated when optimistic forecasts for growth in nuclear power generation were not realized. The other factor which is affecting U.S. uranium production is that some other countries, notably Australia and Canada, possess higher quality uranium reserves that can be mined at lower costs than those of the United States. Realizing its competitive advantage, Canada was the world`s largest producer in 1993 with an output of 23.9 million pounds U{sub 3}O{sub 8} (9.2 thousand metric tons U). The U.S. uranium industry, responding to over a decade of declining market prices, has downsized and adopted less costly and more efficient production methods. The main result has been a suspension of production from conventional mines and mills. Since mid-1992, only nonconventional production facilities, chiefly in situ leach (ISL) mining and byproduct recovery, have operated in the United States. In contrast, nonconventional sources provided only 13 percent of the uranium produced in 1980. ISL mining has developed into the most cost efficient and environmentally acceptable method for producing uranium in the United States. The process, also known as solution mining, differs from conventional mining in that solutions are used to recover uranium from the ground without excavating the ore and generating associated solid waste. This article describes the current ISL Yang technology and its regulatory approval process, and provides an analysis of the factors favoring ISL mining over conventional methods in a declining uranium market.

  14. Ferrimyoglobin-Fluoride.

    ERIC Educational Resources Information Center

    Russo, Steven O.; Hanania, George I. H.

    1990-01-01

    Described is an experiment which is designed to investigate the reaction of the protein ferrimyoglobin with fluoride. The activity uses readily available apparatus and the technique of optical absorbance for measurement of concentrations. Experimental design, procedures, and treatment of the equilibrium data are detailed. (CW)

  15. Heavy Metal Fluoride Glasses.

    DTIC Science & Technology

    1987-04-01

    relatively low refractive Indices in the visible range of about 1.5-1.9 and fairly good chemical resistance towards water and weak acids. Their...particularly interesting to compare with crystalline fluorides (Refs. 25, 37) such as 7800 spinel-type Li2NiF4 ; 7700 rutile-type NiF2 ; 7500 perovskite-type

  16. Fluorine (soluble fluoride)

    Integrated Risk Information System (IRIS)

    Fluorine ( soluble fluoride ) ; CASRN 7782 - 41 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for No

  17. Ferrimyoglobin-Fluoride.

    ERIC Educational Resources Information Center

    Russo, Steven O.; Hanania, George I. H.

    1990-01-01

    Described is an experiment which is designed to investigate the reaction of the protein ferrimyoglobin with fluoride. The activity uses readily available apparatus and the technique of optical absorbance for measurement of concentrations. Experimental design, procedures, and treatment of the equilibrium data are detailed. (CW)

  18. Other Fluoride Products

    MedlinePlus

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

  19. Salt fluoridation and oral health.

    PubMed

    Marthaler, Thomas M

    2013-11-01

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

  20. Mapping of fluoride endemic areas and assessment of fluoride exposure.

    PubMed

    Viswanathan, Gopalan; Jaswanth, A; Gopalakrishnan, S; Siva ilango, S

    2009-02-15

    The prevalence of fluorosis is mainly due to the consumption of more fluoride through drinking water. It is necessary to find out the fluoride endemic areas to adopt remedial measures to the people on the risk of fluorosis. The objectives of this study are to estimate the fluoride exposure through drinking water from people of different age group and to elucidate the fluoride endemic areas through mapping. Assessment of fluoride exposure was achieved through the estimation fluoride level in drinking water using fluoride ion selective electrode method. Google earth and isopleth technique were used for mapping of fluoride endemic areas. From the study it was observed that Nilakottai block of Dindigul district in Tamil Nadu is highly fluoride endemic. About 88% of the villages in this block have fluoride level more than the prescribed permissible limit in drinking water. Exposure of fluoride among different age groups was calculated in this block, which comprises 32 villages. The maximum estimated exposure doses were 0.19 mg/kg/day for infants, 0.17 mg/kg/day for children and 0.10 mg/kg/day for adults. When compared with adequate intake of minimal safe level exposure dose of 0.01 mg/kg/day for infants and 0.05 mg/kg/day for other age groups, a health risk due to fluorosis to the people in Nilakottai block has become evident. From the results, the people in Nilakottai block are advised to consume drinking water with fluoride level less than 1 mg/l. It has been recommended to the government authorities to take serious steps to supply drinking water with low fluoride concern for the fluorosis affected villages.

  1. Uranium deposits of the northern part of the Boulder Batholith, Montana

    USGS Publications Warehouse

    Becraft, George E.

    1955-01-01

    Uranium minerals and radioactivity anomalies occur in many silver-lead veins and chalcedony veins and vein zones in the Boulder batholith of southwestern Montanao Pitchblende has been identified in a few silver-lead veins. These veins occupy shear zones along which there is no evidence of large-scale lateral displacement. The wall rock adjacent to the veins is intensely silicified and sencitized quartz monzonite and granodiortte. The veins have yielded substantial quantities of lead, silver, zinc, and gold. The silver-lead veins consist principal1y of galena, spha1erite, tetrahedrite, cha1copyrite and pyrite in a gangue of light to dark gray quartz, altered rock, gouge, and subordinate chalcedony and carbonate minerals. No anomalous radioactivity nor uranium minerals have been found in similar veins in pre-batholithic rocks of the area. Chalcedony veins and vein zones, some of which are ttraniferous, are distinctly different from the silver-lead veins and, with a single except1on, are known only in the batholith. The chalcedony vein zones consist of one or more discontinuous stringers or veins of cha1cedony and microcrystalline quartz in silicified and sericitized quartz monzonite and granodiorite, and in less strongly altered alaskite. On1y small amounts of silver ore have been produced from these chalcedony veins and vein zones. All of the veins are ear1y Tertiary in age, but the silver-lead veins probably are older than the chalcedony veins. Uranium is closely associated with chalcedory and microcrystalline quartz in both types of veins. This association suggests that all of the uranium in the area is of the same age. If so, some of the silver-lead veins must have been reopened during the period of chalcedony vein formation.

  2. Removal of uranium and fluorine from wastewater by double-functional microsphere adsorbent of SA/CMC loaded with calcium and aluminum

    NASA Astrophysics Data System (ADS)

    Wu, Liping; Lin, Xiaoyan; Zhou, Xingbao; Luo, Xuegang

    2016-10-01

    A novel dual functional microsphere adsorbent of alginate/carboxymethyl cellulose sodium composite loaded with calcium and aluminum (SA/CMC-Ca-Al) is prepared by an injection device to remove fluoride and uranium, respectively, from fluoro-uranium mixed aqueous solution. Batch experiments are performed at different conditions: pH, temperature, initial concentration and contact time. The results show that the maximum adsorption amount for fluoride is 35.98 mg/g at pH 2.0, 298.15 K concentration 100 mg/L, while that for uranium is 101.76 mg/g at pH 4.0, 298.15 K concentration 100 mg/L. Both of the adsorption process could be well described by Langmuir model. The adsorption kinetic data is fitted well with pseudo-first-order model for uranium and pseudo-second-order model for fluoride. Thermodynamic parameters are also evaluated, indicating that the adsorption of uranium on SA/CMC-Ca-Al is a spontaneous and exothermic process, while the removal of fluoride is non-spontaneous and endothermic process. The mechanism of modification and adsorption process on SA/CMC-Ca-Al is characterized by FT-IR, SEM, EDX and XPS. The results show that Ca (II) and Al (III) are loaded on SA/CMC through ion-exchange of sodium of SA/CMC. The coordination reaction and ion-exchange happen during the adsorption process between SA/CMC-Ca-Al and uranium, fluoride. Results suggest that the SA/CMC-Ca-Al adsorbent has a great potential in removing uranium and fluoride from aqueous solution.

  3. Uranium and Thorium

    ERIC Educational Resources Information Center

    Finch, Warren I.

    1978-01-01

    The results of President Carter's policy on non-proliferation of nuclear weapons are expected to slow the growth rate in energy consumption, put the development of the breeder reactor in question, halt plans to reprocess and recycle uranium and plutonium, and expand facilities to supply enriched uranium. (Author/MA)

  4. URANIUM SEPARATION PROCESS

    DOEpatents

    McVey, W.H.; Reas, W.H.

    1959-03-10

    The separation of uranium from an aqueous solution containing a water soluble uranyl salt is described. The process involves adding an alkali thiocyanate to the aqueous solution, contacting the resulting solution with methyl isobutyl ketons and separating the resulting aqueous and organic phase. The uranium is extracted in the organic phase as UO/sub 2/(SCN)/sub/.

  5. Uranium: A Dentist's perspective

    PubMed Central

    Toor, R. S. S.; Brar, G. S.

    2012-01-01

    Uranium is a naturally occurring radionuclide found in granite and other mineral deposits. In its natural state, it consists of three isotopes (U-234, U-235 and U-238). On an average, 1% – 2% of ingested uranium is absorbed in the gastrointestinal tract in adults. The absorbed uranium rapidly enters the bloodstream and forms a diffusible ionic uranyl hydrogen carbonate complex (UO2HCO3+) which is in equilibrium with a nondiffusible uranyl albumin complex. In the skeleton, the uranyl ion replaces calcium in the hydroxyapatite complex of the bone crystal. Although in North India, there is a risk of radiological toxicity from orally ingested natural uranium, the principal health effects are chemical toxicity. The skeleton and kidney are the primary sites of uranium accumulation. Acute high dose of uranyl nitrate delays tooth eruption, and mandibular growth and development, probably due to its effect on target cells. Based on all previous research and recommendations, the role of a dentist is to educate the masses about the adverse effects of uranium on the overall as well as the dental health. The authors recommended that apart from the discontinuation of the addition of uranium to porcelain, the Public community water supplies must also comply with the Environmental Protection Agency (EPA) standards of uranium levels being not more than 30 ppb (parts per billion). PMID:24478959

  6. International uranium market

    SciTech Connect

    Neff, T.L.; Jacoby, H.D.

    1980-12-01

    The international uranium market is affected by many of the same concerns that now attend all trade in energy: the adequacy of the resource base, price uncertainty, and worries about security of access. Uranium, like energy generally, is now a strategic commodity for reasons of economic security. Uranium is also the subject of international security concerns because of its association with the proliferation of nuclear weapons. Proliferation is a subject of disagreement among nations - with some arguing that access to uranium or enriched fuel should be coupled to restraint in technological decisions and acceptance of wide-ranging safeguards; the net result is yet another dimension of uncertainty about an energy commodity that many nations feel is vital to their future. These security concerns are related to the nature and behavior of the international market for nuclear fuels. Without adequate information, the worst is usually assumed. Thus, a clearer view of the nature of supply and demand, of government policy formulation, and of market functioning can help relieve at least some of the security worries felt by those in charge of national energy policies. It is the purpose of this paper to improve this understanding. The following topics are discussed: Uranium Demand; Uranium Supply; Major Uranium Producers - Australia, Canada, South Africa, Namibia, Niger; Major Consumers - Japan, France, West Germany; The Uranium Market; and Issues and Implications.

  7. Uranium and Thorium

    ERIC Educational Resources Information Center

    Finch, Warren I.

    1978-01-01

    The results of President Carter's policy on non-proliferation of nuclear weapons are expected to slow the growth rate in energy consumption, put the development of the breeder reactor in question, halt plans to reprocess and recycle uranium and plutonium, and expand facilities to supply enriched uranium. (Author/MA)

  8. DECONTAMINATION OF URANIUM

    DOEpatents

    Spedding, F.H.; Butler, T.A.

    1962-05-15

    A process is given for separating fission products from uranium by extracting the former into molten aluminum. Phase isolation can be accomplished by selectively hydriding the uranium at between 200 and 300 deg C and separating the hydride powder from coarse particles of fissionproduct-containing aluminum. (AEC)

  9. 16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. VIEW OF THE ENRICHED URANIUM RECOVERY SYSTEM. ENRICHED URANIUM RECOVERY PROCESSED RELATIVELY PURE MATERIALS AND SOLUTIONS AND SOLID RESIDUES WITH RELATIVELY LOW URANIUM CONTENT. URANIUM RECOVERY INVOLVED BOTH SLOW AND FAST PROCESSES. (4/4/66) - Rocky Flats Plant, General Manufacturing, Support, Records-Central Computing, Southern portion of Plant, Golden, Jefferson County, CO

  10. Health Effects Associated with Water Fluoridation.

    ERIC Educational Resources Information Center

    Richmond, Virginia L.

    1979-01-01

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

  11. Use of fluorides in dental caries management.

    PubMed

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

    2010-01-01

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

  12. Health Effects Associated with Water Fluoridation.

    ERIC Educational Resources Information Center

    Richmond, Virginia L.

    1979-01-01

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

  13. METHOD FOR PURIFYING URANIUM

    DOEpatents

    Kennedy, J.W.; Segre, E.G.

    1958-08-26

    A method is presented for obtaining a compound of uranium in an extremely pure state and in such a condition that it can be used in determinations of the isotopic composition of uranium. Uranium deposited in calutron receivers is removed therefrom by washing with cold nitric acid and the resulting solution, coataining uranium and trace amounts of various impurities, such as Fe, Ag, Zn, Pb, and Ni, is then subjected to various analytical manipulations to obtain an impurity-free uranium containing solution. This solution is then evaporated on a platinum disk and the residue is ignited converting it to U2/sub 3//sub 8/. The platinum disk having such a thin film of pure U/sub 2/O/sub 8/ is suitable for use with isotopic determination techaiques.

  14. Uranium dioxide electrolysis

    DOEpatents

    Willit, James L [Batavia, IL; Ackerman, John P [Prescott, AZ; Williamson, Mark A [Naperville, IL

    2009-12-29

    This is a single stage process for treating spent nuclear fuel from light water reactors. The spent nuclear fuel, uranium oxide, UO.sub.2, is added to a solution of UCl.sub.4 dissolved in molten LiCl. A carbon anode and a metallic cathode is positioned in the molten salt bath. A power source is connected to the electrodes and a voltage greater than or equal to 1.3 volts is applied to the bath. At the anode, the carbon is oxidized to form carbon dioxide and uranium chloride. At the cathode, uranium is electroplated. The uranium chloride at the cathode reacts with more uranium oxide to continue the reaction. The process may also be used with other transuranic oxides and rare earth metal oxides.

  15. Uranium triamidoamine chemistry.

    PubMed

    Gardner, Benedict M; Liddle, Stephen T

    2015-07-07

    Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren-uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium-metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren-uranium complexes.

  16. URANIUM PRECIPITATION PROCESS

    DOEpatents

    Thunaes, A.; Brown, E.A.; Smith, H.W.; Simard, R.

    1957-12-01

    A method for the recovery of uranium from sulfuric acid solutions is described. In the present process, sulfuric acid is added to the uranium bearing solution to bring the pH to between 1 and 1.8, preferably to about 1.4, and aluminum metal is then used as a reducing agent to convert hexavalent uranium to the tetravalent state. As the reaction proceeds, the pH rises amd a selective precipitation of uranium occurs resulting in a high grade precipitate. This process is an improvement over the process using metallic iron, in that metallic aluminum reacts less readily than metallic iron with sulfuric acid, thus avoiding consumption of the reducing agent and a raising of the pH without accomplishing the desired reduction of the hexavalent uranium in the solution. Another disadvantage to the use of iron is that positive ferric ions will precipitate with negative phosphate and arsenate ions at the pH range employed.

  17. Silver cyanide

    Integrated Risk Information System (IRIS)

    Silver cyanide ; CASRN 506 - 64 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  18. Water fluoridation and oral health.

    PubMed

    Harding, Máiréad Antoinette; O'Mullane, Denis Martin

    2013-11-01

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

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

    PubMed

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

    2014-08-01

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

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

    PubMed

    Clark, D C

    1982-06-01

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

  1. Microhardness of dentine in primary teeth after topical fluoride applications.

    PubMed

    Chu, C H; Lo, Edward C M

    2008-06-01

    This study measured the microhardness of arrested dentinal caries on primary teeth receiving regular fluoride applications after 30 months. Caries on primary upper anterior teeth of preschool children were randomly assigned to receive 38% silver diamine fluoride every 12 months or 5% sodium fluoride varnish every 3 months. Lesions that were hard on probing were considered arrested. At 30 months, very mobile teeth were extracted, sectioned, and polished and they underwent Knoop hardness number (KHN) measurements at sites below the surface at the center of the carious lesion every 25 microm toward the pulp. Three sets of measurements were made on parallel tracks approximately 150-200 microm apart, and the median KHN at each depth were analyzed. Five arrested and five soft carious lesions were examined. Within the outer 25-200 microm, the median KHN of arrested carious lesions (range, 20-46 or 196-451 MPa) were greater than those of soft carious lesions (range, 5-20, or 49-196 MPa). The difference between them, however, was not statistically significant. At a distance of 225 microm or more from the surface of the lesion, the median KHN of both groups were between 20 and 30 (196-294 MPa). The outermost dentinal surface of carious lesions that had been arrested by topical fluoride application was harder than that of active carious lesions. At a distance of 225 microm or more from the lesion surface, the microhardness of both arrested and soft dentinal caries was similar.

  2. Magnetic behaviour of layered Ag(II) fluorides

    NASA Astrophysics Data System (ADS)

    McLain, Sylvia E.; Dolgos, Michelle R.; Tennant, D. Alan; Turner, John F. C.; Barnes, Ted; Proffen, Thomas; Sales, Brian C.; Bewley, Robert I.

    2006-07-01

    Fluoride phases that contain the spin-1/2 4d9 Ag(II) ion have recently been predicted to have interesting or unusual magnetochemistry, owing to their structural similarity to the 3d9 Cu(II) cuprates and the covalence associated with this unusual oxidation state of silver. Here we present a comprehensive study of structure and magnetism in the layered Ag(II) fluoride Cs2AgF4, using magnetic susceptometry, inelastic neutron scattering techniques and both X-ray and neutron powder diffraction. We find that this material is well described as a two-dimensional ferromagnet, in sharp contrast to the high-TC cuprates and a previous report in the literature. Analyses of the structural data show that Cs2AgF4 is orbitally ordered at all temperatures of measurement. Therefore, we suggest that orbital ordering may be the origin of the ferromagnetism we observe in this material.

  3. PROCESS OF RECOVERING URANIUM

    DOEpatents

    Kilner, S.B.

    1959-12-29

    A method is presented for separating and recovering uranium from a complex mixure of impurities. The uranium is dissolved to produce an aqueous acidic solution including various impurities. In accordance with one method, with the uranium in the uranyl state, hydrogen cyanide is introduced into the solution to complex the impurities. Subsequently, ammonia is added to the solution to precipitate the uraniunn as ammonium diuranate away from the impurities in the solution. Alternatively, the uranium is precipitated by adding an alkaline metal hydroxide. In accordance with the second method, the uranium is reduced to the uranous state in the solution. The reduced solution is then treated with solid alkali metal cyanide sufficient to render the solution about 0.1 to 1.0 N in cyanide ions whereat cyanide complex ions of the metal impurities are produced and the uranium is simultaneously precipituted as uranous hydroxide. Alternatively, hydrogen cyanide may be added to the reduced solution and the uranium precipitated subsequently by adding ammonium hydroxide or an alkali metal hydroxide. Other refinements of the method are also disclosed.

  4. India's Worsening Uranium Shortage

    SciTech Connect

    Curtis, Michael M.

    2007-01-15

    As a result of NSG restrictions, India cannot import the natural uranium required to fuel its Pressurized Heavy Water Reactors (PHWRs); consequently, it is forced to rely on the expediency of domestic uranium production. However, domestic production from mines and byproduct sources has not kept pace with demand from commercial reactors. This shortage has been officially confirmed by the Indian Planning Commission’s Mid-Term Appraisal of the country’s current Five Year Plan. The report stresses that as a result of the uranium shortage, Indian PHWR load factors have been continually decreasing. The Uranium Corporation of India Ltd (UCIL) operates a number of underground mines in the Singhbhum Shear Zone of Jharkhand, and it is all processed at a single mill in Jaduguda. UCIL is attempting to aggrandize operations by establishing new mines and mills in other states, but the requisite permit-gathering and development time will defer production until at least 2009. A significant portion of India’s uranium comes from byproduct sources, but a number of these are derived from accumulated stores that are nearing exhaustion. A current maximum estimate of indigenous uranium production is 430t/yr (230t from mines and 200t from byproduct sources); whereas, the current uranium requirement for Indian PHWRs is 455t/yr (depending on plant capacity factor). This deficit is exacerbated by the additional requirements of the Indian weapons program. Present power generation capacity of Indian nuclear plants is 4350 MWe. The power generation target set by the Indian Department of Atomic Energy (DAE) is 20,000 MWe by the year 2020. It is expected that around half of this total will be provided by PHWRs using indigenously supplied uranium with the bulk of the remainder provided by breeder reactors or pressurized water reactors using imported low-enriched uranium.

  5. SULPHUR DIOXIDE LEACHING OF URANIUM CONTAINING MATERIAL

    DOEpatents

    Thunaes, A.; Rabbits, F.T.; Hester, K.D.; Smith, H.W.

    1958-12-01

    A process is described for extracting uranlum from uranium containing material, such as a low grade pitchblende ore, or mill taillngs, where at least part of the uraniunn is in the +4 oxidation state. After comminuting and magnetically removing any entrained lron particles the general material is made up as an aqueous slurry containing added ferric and manganese salts and treated with sulfur dioxide and aeration to an extent sufficient to form a proportion of oxysulfur acids to give a pH of about 1 to 2 but insufficient to cause excessive removal of the sulfur dioxide gas. After separating from the solids, the leach solution is adjusted to a pH of about 1.25, then treated with metallic iron in the presence of a precipitant such as a soluble phosphate, arsonate, or fluoride.

  6. Infrared emission spectra or uranium and thorium

    SciTech Connect

    Palmer, B.A.; Phillips, M.V.; Engleman, R. Jr.

    1983-01-01

    The region between 1 and 5.5 ..mu..m has been observed with a high-resolution Fourier transform spectrometer. See-through hollow cathode lamps with calcium fluoride windows were operated at high current. Special precautions were required to minimize interference by blackbody radiation from the hot cathode. Observed lines were measured to an absolute accuracy of about 0.001 cm/sup -1/ and about 5% relative intensity accuracy. The argon carrier gas lines were readily distinguished by their much wider Doppler-broadened linewidths. Many lines were assigned to neutral or singly-ionized thorium on the basis of predicted transition wavenumbers calculated from accurate level lists. However, many lines remain to be assigned. This new spectral data connects to, and extends similar, spectral information given in our uranium and thorium atlases which cover the ultraviolet and visible regions.

  7. Young children and fluoride toothpaste.

    PubMed

    Rock, W P

    1994-07-09

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

  8. [Water fluoridation and public health].

    PubMed

    Barak, Shlomo

    2003-11-01

    Fluoridation in Israel was first mooted in 1973 and finally incorporated into law in November 2002 obligating the Ministry of Health to add fluoride to the nation's water supply. Epidemiology studies in the USA have shown that the addition of one part per million of fluoride to the drinking water reduced the caries rate of children's teeth by 50% to 60% with no side effects. Both the WHO in 1994 and the American Surgeon General's report of 2000 declared that fluoridation of drinking water was the safest and most efficient way of preventing dental caries in all age groups and populations. Opposition to fluoridation has arisen from "antifluoridation" groups who object to the "pollution" of drinking water by the addition of chemicals and mass medication in violation of the "Patient's Rights" law and the Basic Law of Human Dignity and Liberty. A higher prevalence of hip fractures in elderly osteoporotic women and osteosarcoma in teenagers has been reported in areas where excess fluoride exists in the drinking water. However, none of the many independent professional committees reviewing the negative aspects of fluoridation have found any scientific evidence associating fluoridation with any ill-effects or health problems. In Israel, where dental treatment is not included in the basket of Health Services, fluoridation is the most efficient and cheapest way of reducing dental disease, especially for the poorer members of the population.

  9. Depleted uranium management alternatives

    SciTech Connect

    Hertzler, T.J.; Nishimoto, D.D.

    1994-08-01

    This report evaluates two management alternatives for Department of Energy depleted uranium: continued storage as uranium hexafluoride, and conversion to uranium metal and fabrication to shielding for spent nuclear fuel containers. The results will be used to compare the costs with other alternatives, such as disposal. Cost estimates for the continued storage alternative are based on a life-cycle of 27 years through the year 2020. Cost estimates for the recycle alternative are based on existing conversion process costs and Capital costs for fabricating the containers. Additionally, the recycle alternative accounts for costs associated with intermediate product resale and secondary waste disposal for materials generated during the conversion process.

  10. Recovery of uranium values

    DOEpatents

    Brown, K. B.; Crouse, Jr., D. J.; Moore, J. G.

    1959-03-10

    A liquid-liquid extraction method is presented for recovering uranium values from an aqueous acidic solution by means of certain high molecular weight amine fn the amine classes of primary, secondary, heterocyclic secondary, tertiary, or heterocyclic tertiary. The uranium bearing aqueous acidic solution is contacted with the selected anine dissolved in a nonpolar waterimmiscible organfc solvent such as kerosene. The uranium which is substantially completely extracted by the organic phase may be stripped therefrom by water, and recovered from the aqueous phase by treatment into ammonia to precipitate ammonium diuranate.

  11. RECOVERY OF URANIUM VALUES

    DOEpatents

    Brown, K.B.; Crouse, D.J. Jr.; Moore, J.G.

    1959-03-10

    A liquid-liquid extraction method is presented for recovering uranium values from an aqueous acidic solution by means of certain high molecular weight amine in the amine classes of primary, secondary, heterocyclic secondary, tertiary, or heterocyclic tertiary. The uranium bearing aqueous acidic solution is contacted with the selected amine dissolved in a nonpolar water-immiscible organic solvent such as kerosene. The uranium which is substantially completely exiracted by the organic phase may be stripped therefrom by waters and recovered from the aqueous phase by treatment into ammonia to precipitate ammonium diuranate.

  12. Kinetics and mechanism of the reaction of uranium hexafluoride and tritium

    NASA Astrophysics Data System (ADS)

    Maienschein, Jon L.; Sunderland, William E.

    1985-03-01

    Using infrared analysis, we found that the reaction rate of gaseous uranium hexafluoride and tritium is determined solely by the rate at which energy from the radioactive decay of tritium is absorbed in the reaction mixture. Because uranium hexafluoride and tritium absorb β-energy with different efficiencies, the reaction rate is somewhat dependent on the initial reactant concentrations. Reaction products include uranium subfluorides and tritium fluoride. A radiochemistry model has been developed that includes β-energy production and absorption in the gas phase to allow calculation of the reaction yield per ion pair formed. With this model it was found that the reaction mechanism does not include lengthy chain propagation steps-only about 10 uranium hexafluoride molecules are consumed for each ion-pair formed in the gas phase. Many possible reaction steps are suggested that could contribute to the observed overall mechanism.

  13. CONTINUOUS PRECIPITATION METHOD FOR CONVERSION OF URANYL NITRATE TO URANIUM HEXAFLUORIDE

    DOEpatents

    Reinhart, G.M.; Collopy, T.J.

    1962-11-13

    A continuous precipitation process is given for converting a uranyl nitrate solution to uranium tetrafluoride. A stream of the uranyl nitrate solution and a stream of an aqueous ammonium hydroxide solution are continuously introduced into an agitated reaction zone maintained at a pH of 5.0 to 6.5. Flow rates are adjusted to provide a mean residence time of the resulting slurry in the reaction zone of at least 30 minutes. After a startup period of two hours the precipitate is recovered from the effluent stream by filtration and is converted to uranium tetrafluoride by reduction to uranium dioxide with hydrogen and reaction of the uranium dioxide with anhydrous hydrogen fluoride. (AEC)

  14. Water fluoridation and osteoporotic fracture.

    PubMed

    Hillier, S; Inskip, H; Coggon, D; Cooper, C

    1996-09-01

    Osteoporotic fractures constitute a major public health problem. These fractures typically occur at the hip, spine and distal forearm. Their pathogenesis is heterogeneous, with contributions from both bone strength and trauma. Water fluoridation has been widely proposed for its dental health benefits, but concerns have been raised about the balance of skeletal risks and benefits of this measure. Fluoride has potent effects on bone cell function, bone structure and bone strength. These effects are mediated by the incorporation of fluoride ions in bone crystals to form fluoroapatite, and through an increase in osteoblast activity. It is believed that a minimum serum fluoride level of 100 ng/ml must be achieved before osteoblasts will be stimulated. Serum levels associated with drinking water fluoridated to 1 ppm are usually several times lower than this value, but may reach this threshold at concentrations of 4 ppm in the drinking water. Animal studies suggest no effect of low-level (0-3 ppm) fluoride intake on bone strength, but a possible decrease at higher levels. Sodium fluoride has been used to treat established osteoporosis for nearly 30 years. Recent trials of this agent, prescribed at high doses, have suggested that despite a marked increase in bone mineral density, there is no concomitant reduction in vertebral fracture incidence. Furthermore, the increase in bone density at the lumbar spine may be achieved at the expense of bone mineral in the peripheral cortical skeleton. As a consequence, high dose sodium fluoride (80 mg daily) is not currently used to treat osteoporosis. At lower doses, recent trials have suggested a beneficial effect on both bone density and fracture. The majority of epidemiological evidence regarding the effect of fluoridated drinking water on hip fracture incidence is based on ecological comparisons. Although one Finnish study suggested that hip fracture rates in a town with fluoridated water were lower than those in a matching town

  15. National Uranium Resource Evaluation: Denver Quadrangle, Colorado

    SciTech Connect

    Hills, F.A.; Dickinson, K.A.; Nash, J.T.; Otton, J.K.; Dodge, H.W.; Granger, H.C.; Robinson, K.; McDonnell, J.R.; Yancey, C.L.

    1982-09-01

    Nine areas in the Denver 1/sup 0/ x 2/sup 0/ Quadrangle, Colorado have been identified as favorable for the occurrence of uranium deposits containing a minimum of 100 tons U/sub 3/O/sub 8/ at grades of 0.01% or better. Six of these areas are in metamorphic and igneous rocks of the Front Range, one is in sedimentary rocks of South Park, and two are in sedimentary rocks of the Great Plains. Favorable areas and the classes of deposits for which they are thought to be favorable are: Area A, The Foothills Favorable Environment (700 km/sup 2/ to a depth of 1500 m); Areas B-D, The Silver Plume Granite Favorable Environment; Area E, Southern Elkhorn Upthrust Favorable Environment; Area F, South Park Favorable Environments (27 km/sup 2/ in units of variable thickness); Area G, Dawson Arkose Favorable Environment (3600 km/sup 2/ with an estimated thickness of 50 m); and Area H, Fox Hills Formation Favorable Environment (700 km/sup 2/ with an estimated thickness of 38 m). Other areas and environments in the Denver Quadrangle have uranium occurences and some have yielded small amounts of uranium ore in the past (for example the Central City district). These areas are ranked as unfavorable because in our judgment the evidence does not suggest favorability for deposits of the minimum size. However, neither empirical data nor genetic models for uranium deposits are adequate presently to make determinations of favorability with confidence, and changes of rank are to be expected in the future.

  16. Time-dependent water dynamics in hydrated uranyl fluoride

    DOE PAGES

    Miskowiec, Andrew J.; Anderson, Brian B.; Herwig, Kenneth W.; ...

    2015-09-15

    In this study, uranyl fluoride is a three-layer, hexagonal structure with significant stacking disorder in the c-direction. It supports a range of unsolved ‘thermodynamic’ hydrates with 0–2.5 water molecules per uranium atom, and perhaps more. However, the relationship between water, hydrate crystal structures, and thermodynamic results, collectively representing the chemical pathway through these hydrate structures, has not been sufficiently elucidated. We used high-resolution quasielastic neutron scattering to study the dynamics of water in partially hydrated uranyl fluoride powder over the course of 4 weeks under closed conditions. The spectra are composed of two quasielastic components: one is associated with translationalmore » diffusive motion of water that is approximately five to six times slower than bulk water, and the other is a slow (on the order of 2–300 ps), spatially bounded water motion. The translational component represents water diffusing between the weakly bonded layers in the crystal, while the bounded component may represent water trapped in subnanometre ‘pockets’ formed by the space between uranium-centred polymerisation units. Complementary neutron diffraction measurements do not show any significant structural changes, suggesting that a chemical conversion of the material does not occur in the thermodynamically isolated system on this timescale.« less

  17. Time-dependent water dynamics in hydrated uranyl fluoride

    SciTech Connect

    Miskowiec, Andrew J.; Anderson, Brian B.; Herwig, Kenneth W.; Huq, Ashfia; Mamontov, Eugene; Rondinone, Adam; Trowbridge, Lee D.

    2015-09-15

    In this study, uranyl fluoride is a three-layer, hexagonal structure with significant stacking disorder in the c-direction. It supports a range of unsolved ‘thermodynamic’ hydrates with 0–2.5 water molecules per uranium atom, and perhaps more. However, the relationship between water, hydrate crystal structures, and thermodynamic results, collectively representing the chemical pathway through these hydrate structures, has not been sufficiently elucidated. We used high-resolution quasielastic neutron scattering to study the dynamics of water in partially hydrated uranyl fluoride powder over the course of 4 weeks under closed conditions. The spectra are composed of two quasielastic components: one is associated with translational diffusive motion of water that is approximately five to six times slower than bulk water, and the other is a slow (on the order of 2–300 ps), spatially bounded water motion. The translational component represents water diffusing between the weakly bonded layers in the crystal, while the bounded component may represent water trapped in subnanometre ‘pockets’ formed by the space between uranium-centred polymerisation units. Complementary neutron diffraction measurements do not show any significant structural changes, suggesting that a chemical conversion of the material does not occur in the thermodynamically isolated system on this timescale.

  18. Depleted Uranium: Technical Brief

    EPA Pesticide Factsheets

    This technical brief provides accepted data and references to additional sources for radiological and chemical characteristics, health risks and references for both the monitoring and measurement, and applicable treatment techniques for depleted uranium.

  19. Uranium Location Database Compilation

    EPA Pesticide Factsheets

    EPA has compiled mine location information from federal, state, and Tribal agencies into a single database as part of its investigation into the potential environmental hazards of wastes from abandoned uranium mines in the western United States.

  20. PURIFICATION OF URANIUM FUELS

    DOEpatents

    Niedrach, L.W.; Glamm, A.C.

    1959-09-01

    An electrolytic process of refining or decontaminating uranium is presented. The impure uranium is made the anode of an electrolytic cell. The molten salt electrolyte of this cell comprises a uranium halide such as UF/sub 4/ or UCl/sub 3/ and an alkaline earth metal halide such as CaCl/sub 2/, BaF/sub 2/, or BaCl/sub 2/. The cathode of the cell is a metal such as Mn, Cr, Co, Fe, or Ni which forms a low melting eutectic with U. The cell is operated at a temperature below the melting point of U. In operation the electrodeposited uranium becomes alloyed with the metal of the cathode, and the low melting alloy thus formed drips from the cathode.

  1. 300 AREA URANIUM CONTAMINATION

    SciTech Connect

    BORGHESE JV

    2009-07-02

    {sm_bullet} Uranium fuel production {sm_bullet} Test reactor and separations experiments {sm_bullet} Animal and radiobiology experiments conducted at the. 331 Laboratory Complex {sm_bullet} .Deactivation, decontamination, decommissioning,. and demolition of 300 Area facilities

  2. Uranium purchases report 1993

    SciTech Connect

    Not Available

    1994-08-10

    Data reported by domestic nuclear utility companies in their responses to the 1991 through 1993 ``Uranium Industry Annual Survey,`` Form EIA-858, Schedule B,`` Uranium Marketing Activities,`` are provided in response to the requirements in the Energy Policy Act 1992. Appendix A contains an explanation of Form EIA-858 survey methodologies with emphasis on the processing of Schedule B data. Additional information published in this report not included in Uranium Purchases Report 1992, includes a new data table. Presented in Table 1 are US utility purchases of uranium and enrichment services by origin country. Also, this report contains additional purchase information covering average price and contract duration. Table 2 is an update of Table 1 and Table 3 is an update of Table 2 from the previous year`s report. The report contains a glossary of terms.

  3. Uranium concentrations in asparagus

    SciTech Connect

    Tiller, B.L.; Poston, T.M.

    1992-05-01

    Concentrations of uranium were determined in asparagus collected from eight locations near and ten locations on the Hanford Site southcentral Washington State. Only one location (Sagemoor) had samples with elevated concentrations. The presence of elevated uranium in asparagus at Sagemoor may be explained by the elevated levels in irrigation water. These levels of uranium are comparable to levels previously reported upstream and downstream of the 300-FF-1 Operable Unit on the Hanford Site (0.0008 {mu}g/g), but were below the 0.020-{mu}g/g level reported for brush collected at Sagemoor in a 1982 study. Concentrations at all other onsite and offsite sample locations were considerably lower than concentrations reported immediately upstream and downstream of the 300-FF-1 Operable Unit. Using an earlier analysis of the uranium concentrations in asparagus collected from the Hanford Site constitutes a very small fraction of the US Department of Energy effective dose equivalent limit of 100 mrem.

  4. Drinking water fluoridation and bone.

    PubMed

    Allolio, B; Lehmann, R

    1999-01-01

    Drinking water fluoridation has an established role in the prevention of dental caries, but may also positively or negatively affect bone. In bone fluoride is incorporated into hydroxylapatite to form the less soluble fluoroapatite. In higher concentrations fluoride stimulates osteoblast activity leading to an increase in cancellous bone mass. As optimal drinking water fluoridation (1 mg/l) is widely used, it is of great interest, whether long-term exposition to artificial water fluoridation has any impact on bone strength, bone mass, and -- most importantly -- fracture rate. Animal studies suggest a biphasic pattern of the effect of drinking water fluoridation on bone strength with a peak strength at a bone fluoride content of 1200 ppm followed by a decline at higher concentrations eventually leading to impaired bone quality. These changes are not paralleled by changes in bone mass suggesting that fluoride concentrations remain below the threshold level required for activation of osteoblast activity. Accordingly, in most epidemiological studies in humans bone mass was not altered by optimal drinking water fluoridation. In contrast, studies on the effect on hip fracture rate gave conflicting results ranging from an increased fracture incidence to no effect, and to a decreased fracture rate. As only ecological studies have been performed, they may be biased by unknown confounding factors -- the so-called ecological fallacy. However, the combined results of these studies indicate that any increase or decrease in fracture rate is likely to be small. It has been calculated that appropriately designed cohort studies to solve the problem require a sample size of >400,000 subjects. Such studies will not be performed in the foreseeable future. Future investigations in humans should, therefore, concentrate on the effect of long-term drinking water fluoridation on bone fluoride content and bone strength.

  5. ANODIC TREATMENT OF URANIUM

    DOEpatents

    Kolodney, M.

    1959-02-01

    A method is presented for effecting eloctrolytic dissolution of a metallic uranium article at a uniform rate. The uranium is made the anode in an aqueous phosphoric acid solution containing nitrate ions furnished by either ammonium nitrate, lithium nitrate, sodium nitrate, or potassium nitrate. A stainless steel cathode is employed and electrolysls carried out at a current density of about 0.1 to 1 ampere per square inch.

  6. URANIUM SEPARATION PROCESS

    DOEpatents

    Lyon, W.L.

    1962-04-17

    A method of separating uranium oxides from PuO/sub 2/, ThO/sub 2/, and other actinide oxides is described. The oxide mixture is suspended in a fused salt melt and a chlorinating agent such as chlorine gas or phosgene is sparged through the suspension. Uranium oxides are selectively chlorinated and dissolve in the melt, which may then be filtered to remove the unchlorinated oxides of the other actinides. (AEC)

  7. Uranium purchases report 1994

    SciTech Connect

    1995-07-01

    US utilities are required to report to the Secretary of Energy annually the country of origin and the seller of any uranium or enriched uranium purchased or imported into the US, as well as the country of origin and seller of any enrichment services purchased by the utility. This report compiles these data and also contains a glossary of terms and additional purchase information covering average price and contract duration. 3 tabs.

  8. Worldwide developments in uranium

    SciTech Connect

    Hoellen, E.E.

    1987-05-01

    World uranium production will continue to change in most major producing nations. Canadian production will increase and will be increasingly dominated by western producers as eastern Canadian high-cost production declines. Australian production will increase as major projects come into operation before 2000. US production will stabilize through the end of the century. South African production will be dependent upon the worldwide support for economic sanctions. China's entry into the world market injects yet another variable into the already cloudy supply picture. Many risks and uncertainties will face uranium producers through the 1980s. Recognizing that the uranium industry is not a fast-growing market, many existing and potential producers are seeking alternate investment courses, causing a restructuring of the world uranium production industry in ways not anticipated even a few years ago. During the restructuring process, world uranium production will most likely continue to exceed uranium consumption, resulting in a further buildup of world uranium inventories. Inventory sales will continue to redistribute this material. As inventory selling runs its course, users will turn to normal sources of supply, stimulating additional production to meet needs. Stimulation in the form of higher prices will be determined by how fast producers are willing and able to return to the market. Production costs are expected to have an increasing impact as it has become apparent that uranium resources are large in comparison to projected consumption. Conversely, security-of-supply issues have seemed to be of decreasing magnitude as Canada, Australia, and other non-US producers continue to meet delivery commitments.

  9. URANIUM EXTRACTION PROCESS

    DOEpatents

    Baldwin, W.H.; Higgins, C.E.

    1958-12-16

    A process is described for recovering uranium values from acidic aqueous solutions containing hexavalent uranium by contacting the solution with an organic solution comprised of a substantially water-immiscible organlc diluent and an organic phosphate to extract the uranlum values into the organic phase. Carbon tetrachloride and a petroleum hydrocarbon fraction, such as kerosene, are sultable diluents to be used in combination with organlc phosphates such as dibutyl butylphosphonate, trlbutyl phosphine oxide, and tributyl phosphate.

  10. Toxicity of Depleted Uranium

    DTIC Science & Technology

    1997-02-01

    Exposure to Uranium Hexafluoride NUREG /CR- 5566, PNL-7328, Prepared for US Nuclear Regulatory Commission, Washington, DC, 1990. 27. Thun MJ, Baker DB... NUREG /CR-495 1, Prepared for US Nuclear Regulatory Commission, Washington, DC, 1987. 31. Morrow PE, Leach LJ, Smith FA, Goloin RM, Scott JB, Belter HD...of Uranium Hexafluoride, NUREG /CR- 2268, RH, Prepared for Division of Health Siting and Waste Management, Washington, DC, 1982. 32. Eidson AF, Damon

  11. Soviet uranium supply capability

    SciTech Connect

    1990-02-01

    For many years, only limited information concerning uranium deposits in the USSR has been available from Soviet sources. The Soviet Union has, however, cooperated in some past efforts to promote interaction with the international scientific community. For example, in 1984 the Soviet Union hosted the 27th International Geological Congress (IGC). The uranium portion included 50 papers, primarily on uranium deposits in sandstone and metamorphic rocks, presented to about 300 members. The IGC sponsored almost 400 geology field trips, the most noteworthy of which was a five-day trip to the Krivoi Rog iron and uranium district in the south-central Ukraine, including visits to two open-pit iron mines and the underground Novaya uranium mine in Zholtye Vody. That conference was reported in detail on the October 1984 NUEXCO Monthly Report. Some other information that has been made available over the years is contained in the April 1985 Report discussion of uranium deposit classifications. Advanced processing technology, low-cost labor, by-product and co-product recovery, and the large existing production capacity enable MAEI to produce nuclear fuel at low cost. The Soviet Union`s reserve base, technological development, and production experience make it one of the world`s leading producers of nuclear fuel. As additional information is made available for publication, NUEXCO will present updated reports on the nuclear fuel cycle facilities in the Soviet Union.

  12. Fluoride Content in Alcoholic Drinks.

    PubMed

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

    2016-06-01

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

  13. Volumetric determination of uranium using titanous sulfate as reductant before oxidimetric titration

    USGS Publications Warehouse

    Wahlberg, James S.; Skinner, Dwight L.; Rader, Lewis F.

    1956-01-01

    A new method for determining uranium in samples containing 0.05 percent or more U3O8, using titanous sulfate as reducing agent, is much shorter, faster, and has fewer interferences than conventional methods using reductor columns. The sample is dissolved with sulfuric, nitric, perchloric, and hydrofluoric acids. Elements that would otherwise form insoluble fluorides are kept in solution by complexing the fluoride ion with boric acid. A precipitation is made with cupferron to remove interfering elements. The solution is filtered to remove the precipitated cupferrates instead of extracting them with chloroform as is usually done. Filtration is preferred to extraction because any niobium that may be in solution forms an insoluble cupferrate that may be removed by filtering but is very difficult to extract with chloroform. Excess cupferron is destroyed by oxidizing with nitric and perchloric acids, and evaporating to dense fumes of sulfuric acid. The uranium is reduced to U(IV) by the addition of titanous sulfate, with cupric sulfate used as an indicator of the completeness of the reduction. Metallic copper is formed when all the uranium is reduced. The reduced copper is then reoxidized by the addition of mercuric perchlorate, an excess of ferric sulfate added, and the solution titrated immediately with standard ceric sulfate with ferroin as an indicator. Precision of the method compared favorable with methods in common use, both for uranium ores and for most types of uranium-rich materials.

  14. Electrochemical separation of aluminum from uranium for research reactor spent nuclear fuel applications.

    SciTech Connect

    Slater, S. A.; Willit, J. L.; Gay, E. C.; Chemical Engineering

    1999-01-01

    Researchers at Argonne National Laboratory (ANL) are developing an electrorefining process to treat aluminum-based spent nuclear fuel by electrochemically separating aluminum from uranium. The aluminum electrorefiner is modeled after the high-throughput electrorefiner developed at ANL. Aluminum is electrorefined, using a fluoride salt electrolyte, in a potential range of -0.1 V to -0.2 V, while uranium is electrorefined in a potential range of -0.3 V to -0.4 V; therefore, aluminum can be selectively separated electrochemically from uranium. A series of laboratory-scale experiments was performed to demonstrate the aluminum electrorefining concept. These experiments involved selecting an electrolyte (determining a suitable fluoride salt composition); selecting a crucible material for the electrochemical cell; optimizing the operating conditions; determining the effect of adding alkaline and rare earth elements to the electrolyte; and demonstrating the electrochemical separation of aluminum from uranium, using a U-Al-Si alloy as a simulant for aluminum-based spent nuclear fuel. Results of the laboratory-scale experiments indicate that aluminum can be selectively electrotransported from the anode to the cathode, while uranium remains in the anode basket.

  15. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ward, Jesse D.; Bowden, Mark; Tom Resch, C.; Eiden, Gregory C.; Pemmaraju, C. D.; Prendergast, David; Duffin, Andrew M.

    2017-01-01

    Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Chemical analyses of these compounds are important for process and environmental monitoring. X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. The effect of hydration state on the sample, a potential complication in interpreting oxygen K-edge spectra, is discussed. These compounds have unique spectral signatures that can be used to identify unknown samples.

  16. Caries management with fluoride agents.

    PubMed

    Lam, Anty; Chu, C H

    2012-11-01

    Dental caries is the single most common, chronic oral disease of childhood. It is progressive and cumulative, and becomes more complex over time. The Surgeon General's Report on Oral Health revealed that more than 51 million school hours are lost each year as a result of dental problems. Contemporary caries management philosophy has changed from the traditional surgical approach to a medical model that emphasizes prevention. Among various strategies for caries prevention or reduction, fluoride therapy has been highly promoted. Various in-office and over-the-counter fluoride products are available for caries prevention. Dental professionals should identify and assess the caries risk level of patients and optimize the use of fluorides in caries management. Since multiple sources of fluoride exposure exist, a coordinated approach to fluoride delivery is essential.

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

    PubMed

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

    2006-08-01

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

  18. In vitro comparative fluoride release, and weight and volume change in light-curing and self-curing glass ionomer materials.

    PubMed

    Wandera, A; Spencer, P; Bohaty, B

    1996-01-01

    The purpose of this study was to evaluate and compare in vitro fluoride release from and weight and volume changes of Photac-Fil, a light-curing polymaleinate restorative glass ionomer, with Ketac-Fil, a self-curing glass ionomer, and Ketac-Silver, a metal reinforced glass ionomer. Five discs of each material, measuring 2 mm height and 5 mm diameter, were suspended in separate vials of distilled water and laboratory artificial saliva. Fluoride release into the solutions was measured using a calibrated fluoride-sensitive ion meter initially at 24 hr and then weekly from 1 to 9 weeks. These results were evaluated statistically using repeated measures analysis of variance. Volumes and weights were recorded at the start and end of the experiment and analyzed using the paired t-test. Photac-Fil released similar amounts of fluoride to Ketac-Silver, but significantly less than Ketac-Fil in distilled water (P < or = 0.05). In artificial saliva, Photac-Fil released similar amounts to Ketac-Fil, but significantly more than Ketac-Silver (P < or = 0.05). Photac-Fil volume increased in distilled water and artificial saliva (P < or = 0.05) as did Ketac-Fil and Ketac-Silver in artificial saliva (P < or = 0.05). The only material that demonstrated significant net weight increase was Ketac-Silver in artificial saliva (P < or = 0.05). In summary, differences in fluoride release between these three glass ionomer materials varied as a function of the media in which they were stored. Whereas Ketac-Fil exhibited significantly greater fluoride release than the other materials in distilled water, in artificial saliva Ketac-Fil and Photac-Fil exhibited comparable fluoride release. Dimensional change, as evaluated by volume and weight differences, was also affected by storage media.

  19. Topical fluoride for caries prevention

    PubMed Central

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

    2015-01-01

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

  20. Process for electrolytically preparing uranium metal

    DOEpatents

    Haas, Paul A.

    1989-08-01

    A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

  1. Process for electrolytically preparing uranium metal

    DOEpatents

    Haas, Paul A.

    1989-01-01

    A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

  2. Determination of Stability Constants of Hydrogen and Aluminum Fluorides with a Fluoride-Selective Electrode

    SciTech Connect

    Baumann, E.W.

    2003-01-06

    The ability to directly determine free fluoride ion concentration (or mean activity) simplifies gathering and interpretation of experimental data for studies of metal complexes. In this work, the new lanthanum fluoride electrode was used to measure free fluoride ion in an investigation of the hydrogen-fluoride and aluminum-fluoride systems in NH4NO3.

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  5. Influence of uranium hydride oxidation on uranium metal behaviour

    SciTech Connect

    Patel, N.; Hambley, D.; Clarke, S.A.; Simpson, K.

    2013-07-01

    This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

  6. The effect of solubility on inhaled uranium compound clearance: a review.

    PubMed

    Eidson, A F

    1994-07-01

    Research on inhaled industrial uranium compounds has shown that solubility influences the target organ, the toxic response, and the mode of uranium excretion. Consideration of physical chemical properties indicates that the dissolution of industrial uranium oxides is expected to be strongly dependent on process history, and that dissolved uranium exists in vivo in the hexavalent state regardless of the oxidation state of the inhaled compound. The overall clearance rate of uranium compounds from the lung reflects both mechanical and dissolution processes. Mechanical clearance rates are highly variable among individual workers studied, but dissolution rates of inhaled compounds are similar among the mammalian species studied. Results from experiments in vivo and accidental worker exposures indicate that the uptake of dissolved uranium from the lung is more rapid than the dissolution rate of most industrial uranium compounds. These results indicate that the absorption rate of inhaled uranium can be approximated by the dissolution rate of most industrial compounds. Dissolution rates of UF6 and UO2(NO3)2 are more rapid than the mechanical clearance rates and dominate the overall lung clearance rate. UF4, UO3, and ammonium diuranate have intermediate dissolution rates that are similar to mechanical clearance rates and exhibit high variability among uranium specimens. U3O8 and UO2 have slow dissolution rates such that pulmonary clearance rates are dominated by mechanical processes. Industrial uranium ores, oxides, and fluorides are often variable mixtures of relatively soluble and insoluble fractions. Dissolution rates measured in vitro can be used with biokinetics models to reduce the uncertainties in dosimetry associated with inhalation exposures to mixtures.

  7. The Dissolution of Uranium Oxides in HB-Line Phase 1 Dissolvers

    SciTech Connect

    Gray, J.H.

    2003-08-28

    A series of characterization and dissolution studies has been performed to define flowsheet conditions for the dissolution of uranium oxide materials in dissolvers. The samples selected for analysis were uranium oxide materials. The selection of these uranium oxide materials for characterization and dissolution studies was based on high enriched uranium content and trace levels of plutonium. Test results from the characterization study identified ferric oxide (Fe2O3) and iron/chromium/nickel (Fe/Cr/Ni) particles as impurities along with the tri-uranium oxide (U3O8) and uranium trioxide (UO3). The weight percent uranium in this material was found to vary depending on the impurity content. The trace impurity plutonium appears to be associated with the Fe/Cr/Ni particles. A small amount of absorbed moisture and waters of hydration is present. Most of the uranium oxides easily dissolved in low-molar nitric acid solutions without fluoride within one to two hours at solution temperature s between 60-80 degrees C. A small amount of residue remained following this dissolution step. To assure complete dissolution of uranium from these oxide materials, an additional dissolution step at 90 degrees C to boiling for at least one to two hours has been suggested. Only trace amounts of iron associated with Fe2O3 and Fe/Cr/Ni particles will dissolve during the dissolution steps. Neither hydrogen nor heat will be generated during the dissolution of these uranium oxide materials in nitric acid solutions. Some brown nitrogen dioxide (NO2) fumes will be generated during the dissolution of U3O8.

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

    SciTech Connect

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

    1989-01-01

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

  9. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  10. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  11. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  12. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Hydrogen fluoride. 173.163 Section 173.163... Hydrogen fluoride. (a) Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged as follows: (1) In... filling ratio of 0.84. (b) A cylinder removed from hydrogen fluoride service must be condemned...

  13. Thermodynamics of the conversion of calcium and magnesium fluorides to the parent metal oxides and hydrogen fluoride

    SciTech Connect

    West, M.H.; Axler, K.M.

    1997-02-01

    The authors have used thermodynamic modeling to examine the reaction of calcium fluoride (CaF{sub 2}) and magnesium fluoride (MgF{sub 2}) with water (H{sub 2}O) at elevated temperatures. The calculated, equilibrium composition corresponds to the global free-energy minimum for the system. Optimum, predicted reaction temperatures and reactant mole ratios are reported for the recovery of hydrogen fluoride (HF), a valuable industrial feedstock. Complete conversion of MgF{sub 2} is found at 1,000 C and a ratio of 40 moles of H{sub 2}O per 1 mole of MgF{sub 2}. For CaF{sub 2}, temperatures as high as 1,400 C are required for complete conversion at a corresponding mole ratio of 40 moles of H{sub 2}O per 1 mole of CaF{sub 2}. The authors discuss the presence of minor chemical constituents as well as the stability of various potential container materials for the pyrohydrolysis reactions at elevated temperatures. CaF{sub 2} and MgF{sub 2} slags are available as wastes at former uranium production facilities within the Department of Energy Complex and other facilities regulated by the Nuclear Regulatory Commission. Recovery of HF from these wastes is an example of environmental remediation at such facilities.

  14. Fluoride-induced chronic renal failure.

    PubMed

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

    1987-08-01

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

  15. METHOD OF RECOVERING URANIUM COMPOUNDS

    DOEpatents

    Poirier, R.H.

    1957-10-29

    S>The recovery of uranium compounds which have been adsorbed on anion exchange resins is discussed. The uranium and thorium-containing residues from monazite processed by alkali hydroxide are separated from solution, and leached with an alkali metal carbonate solution, whereby the uranium and thorium hydrorides are dissolved. The carbonate solution is then passed over an anion exchange resin causing the uranium to be adsorbed while the thorium remains in solution. The uranium may be recovered by contacting the uranium-holding resin with an aqueous ammonium carbonate solution whereby the uranium values are eluted from the resin and then heating the eluate whereby carbon dioxide and ammonia are given off, the pH value of the solution is lowered, and the uranium is precipitated.

  16. Carbide/Fluoride/Silver Self-Lubricating Composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1987-01-01

    Bearing coatings survive at operating temperatures up to 870 degrees C. PS200 composite self-lubricating coating for bearing applications operating at temperatures above failure points of traditional solid lubricants. Excellent friction and wear performance in oxidizing atmospheres up to 1,600 degrees F and reducing atmospheres up to 1,400 degrees F. Performance needed for development of advanced heat engines as adiabatic diesel and Stirling engine.

  17. Carbide/Fluoride/Silver Self-Lubricating Composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1987-01-01

    Bearing coatings survive at operating temperatures up to 870 degrees C. PS200 composite self-lubricating coating for bearing applications operating at temperatures above failure points of traditional solid lubricants. Excellent friction and wear performance in oxidizing atmospheres up to 1,600 degrees F and reducing atmospheres up to 1,400 degrees F. Performance needed for development of advanced heat engines as adiabatic diesel and Stirling engine.

  18. High-pressure structural behaviour of silver(I) fluoride

    NASA Astrophysics Data System (ADS)

    Hull, S.; Berastegui, P.

    1998-09-01

    The high-pressure structural behaviour of AgF has been studied by the powder neutron diffraction technique. The material undergoes a pressure-induced transition at 2.70(2) GPa from the rocksalt structure to the CsCl-type arrangement with a volume change of 0953-8984/10/36/005/img1. On decreasing pressure, the reverse 0953-8984/10/36/005/img2 transition occurs via an intermediate phase possessing the hexagonal anti-NiAs structure. A plausible structural model to explain this observation is provided, together with a discussion of the relative stability of the (anti-) NiAs arrangement as a high-pressure polymorph in binary MX compounds.

  19. AgF X 1Σ+ Silver fluoride

    NASA Astrophysics Data System (ADS)

    Hüttner, W.

    This document is part of Subvolume A1 'Diamagnetic Diatomic Molecules. Part 1' of Volume 29 'Molecular Constants Mostly from Microwave, Molecular Beam, and Sub-Doppler Laser Spectroscopy' of Landolt-Börnstein - Group II 'Molecules and Radicals'.

  20. Microbial reduction of uranium

    USGS Publications Warehouse

    Lovley, D.R.; Phillips, E.J.P.; Gorby, Y.A.; Landa, E.R.

    1991-01-01

    REDUCTION of the soluble, oxidized form of uranium, U(VI), to insoluble U(IV) is an important mechanism for the immobilization of uranium in aquatic sediments and for the formation of some uranium ores1-10. U(VI) reduction has generally been regarded as an abiological reaction in which sulphide, molecular hydrogen or organic compounds function as the reductant1,2,5,11. Microbial involvement in U(VI) reduction has been considered to be limited to indirect effects, such as microbial metabolism providing the reduced compounds for abiological U(VI) reduction and microbial cell walls providing a surface to stimulate abiological U(VI) reduction1,12,13. We report here, however, that dissimilatory Fe(III)-reducing microorganisms can obtain energy for growth by electron transport to U(VI). This novel form of microbial metabolism can be much faster than commonly cited abiological mechanisms for U(VI) reduction. Not only do these findings expand the known potential terminal electron acceptors for microbial energy transduction, they offer a likely explanation for the deposition of uranium in aquatic sediments and aquifers, and suggest a method for biological remediation of environments contaminated with uranium.

  1. Uranium hexafluoride handling. Proceedings

    SciTech Connect

    Not Available

    1991-12-31

    The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF{sub 6} from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride. Selected papers were processed separately for inclusion in the Energy Science and Technology Database.

  2. Uranium deposits of Brazil

    SciTech Connect

    1991-09-01

    Brazil is a country of vast natural resources, including numerous uranium deposits. In support of the country`s nuclear power program, Brazil has developed the most active uranium industry in South America. Brazil has one operating reactor (Angra 1, a 626-MWe PWR), and two under construction. The country`s economic challenges have slowed the progress of its nuclear program. At present, the Pocos de Caldas district is the only active uranium production. In 1990, the Cercado open-pit mine produced approximately 45 metric tons (MT) U{sub 3}O{sub 8} (100 thousand pounds). Brazil`s state-owned uranium production and processing company, Uranio do Brasil, announced it has decided to begin shifting its production from the high-cost and nearly depleted deposits at Pocos de Caldas, to lower-cost reserves at Lagoa Real. Production at Lagoa Real is schedules to begin by 1993. In addition to these two districts, Brazil has many other known uranium deposits, and as a whole, it is estimated that Brazil has over 275,000 MT U{sub 3}O{sub 8} (600 million pounds U{sub 3}O{sub 8}) in reserves.

  3. Magnesium reduction of uranium oxide

    SciTech Connect

    Elliott, G.R.B.

    1985-08-13

    A method and apparatus are provided for reducing uranium oxide with magnesium to form uranium metal. The reduction is carried out in a molten-salt solution of density greater than 3.4 grams per cubic centimeter, thereby allowing the uranium product to sink and the magnesium oxide byproduct to float, consequently allowing separation of product and byproduct.

  4. Uranium immobilization and nuclear waste

    SciTech Connect

    Duffy, C.J.; Ogard, A.E.

    1982-02-01

    Considerable information useful in nuclear waste storage can be gained by studying the conditions of uranium ore deposit formation. Further information can be gained by comparing the chemistry of uranium to nuclear fission products and other radionuclides of concern to nuclear waste disposal. Redox state appears to be the most important variable in controlling uranium solubility, especially at near neutral pH, which is characteristic of most ground water. This is probably also true of neptunium, plutonium, and technetium. Further, redox conditions that immobilize uranium should immobilize these elements. The mechanisms that have produced uranium ore bodies in the Earth's crust are somewhat less clear. At the temperatures of hydrothermal uranium deposits, equilibrium models are probably adequate, aqueous uranium (VI) being reduced and precipitated by interaction with ferrous-iron-bearing oxides and silicates. In lower temperature roll-type uranium deposits, overall equilibrium may not have been achieved. The involvement of sulfate-reducing bacteria in ore-body formation has been postulated, but is uncertain. Reduced sulfur species do, however, appear to be involved in much of the low temperature uranium precipitation. Assessment of the possibility of uranium transport in natural ground water is complicated because the system is generally not in overall equilibrium. For this reason, Eh measurements are of limited value. If a ground water is to be capable of reducing uranium, it must contain ions capable of reducing uranium both thermodynamically and kinetically. At present, the best candidates are reduced sulfur species.

  5. PROCESS OF PREPARING URANIUM CARBIDE

    DOEpatents

    Miller, W.E.; Stethers, H.L.; Johnson, T.R.

    1964-03-24

    A process of preparing uranium monocarbide is de scribed. Uranium metal is dissolved in cadmium, zinc, cadmium-- zinc, or magnesium-- zinc alloy and a small quantity of alkali metal is added. Addition of stoichiometric amounts of carbon at 500 to 820 deg C then precipitates uranium monocarbide. (AEC)

  6. Strontium-90 fluoride data sheet

    SciTech Connect

    Fullam, H.T.

    1981-06-01

    This report is a compilation of available data and appropriate literature references on the properties of strontium-90 fluoride and nonradioactive strontium fluoride. The objective of the document is to compile in a single source pertinent data to assist potential users in the development, licensing, and use of /sup 90/SrF/sub 2/-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977.

  7. Molten fluoride fuel salt chemistry

    SciTech Connect

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1994-09-01

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

  8. Spectral Diversity Crystalline Fluoride Lasers,

    DTIC Science & Technology

    1981-01-01

    2 4.-. i1.34 I R TUNABLE Table IX XeF Pumoe TM3 +: YLF :1 .Tm:YLF exhibits nearly ideal parameters for high energy operation aa3x10-20cm 2 ESAT 0cm e...host crystal, lithium yttrium fluoride, LiYF*4 ( YLF )" 1..0 Introductin Within the realm of crystalline laser materials,. the class of fluorides...on the host crystal, lithium yttrium fluoride, LiYF4 - often shortened as YLF . Tables I and 12 show the mechanical, thermal, and optical properties

  9. PROCESS FOR RECOVERING URANIUM

    DOEpatents

    MacWood, G.E.; Wilder, C.D.; Altman, D.

    1959-03-24

    A process is described for recovering uranium from deposits on stainless steel liner surfaces of calutrons. The deposit is removed from the stainless steel surface by washing with aqueous nitric acid. The solution obtained containing uranium, chromium, nickels copper, and iron is treated with excess of ammonium hydroxide to precipitatc the uranium, irons and chromium and convert thc nickel and copper to soluble ammonia complexions. The precipitated material is removed, dried, and treated with carbon tetrachloride at an elevated temperature of about 500 to 600 deg C to form a vapor mixture of UCl/sub 4/, UCl/sub 5/, FeCl/ sub 3/, and CrCl/sub 4/. The UCl/sub 4/ is separated from this vapor mixture by selective fractional condensation at a temprrature of about 300 to400 deg C.

  10. Process for recovering uranium

    DOEpatents

    MacWood, G. E.; Wilder, C. D.; Altman, D.

    1959-03-24

    A process useful in recovering uranium from deposits on stainless steel liner surfaces of calutrons is presented. The deposit is removed from the stainless steel surface by washing with aqueous nitric acid. The solution obtained containing uranium, chromium, nickel, copper, and iron is treated with an excess of ammonium hydroxide to precipitnte the uranium, iron, and chromium and convert the nickel and copper to soluble ammonio complexions. The precipitated material is removed, dried and treated with carbon tetrachloride at an elevated temperature of about 500 to 600 deg C to form a vapor mixture of UCl/ sub 4/, UCl/sub 5/, FeCl/sub 3/, and CrCl/sub 4/. The UCl/sub 4/ is separated from this vapor mixture by selective fractional condensation at a temperature of about 500 to 400 deg C.

  11. EXTRACTION OF URANIUM

    DOEpatents

    Kesler, R.D.; Rabb, D.D.

    1959-07-28

    An improved process is presented for recovering uranium from a carnotite ore. In the improved process U/sub 2/O/sub 5/ is added to the comminuted ore along with the usual amount of NaCl prior to roasting. The amount of U/sub 2/O/ sub 5/ is dependent on the amount of free calcium oxide and the uranium in the ore. Specifically, the desirable amount of U/sub 2/O/sub 5/ is 3.2% for each 1% of CaO, and 5 to 6% for each 1% of uranium. The mixture is roasted at about 1560 deg C for about 30 min and then leached with a 3 to 9% aqueous solution of sodium carbonate.

  12. Portland Water Fluoridation: A Newspaper Analysis.

    PubMed

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

    2017-03-01

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

  13. LSPR based fiber optic sensor for fluoride impurity sensing in potable water

    NASA Astrophysics Data System (ADS)

    Tambe, Abhay; Kumbhaj, S.; Lalla, N. P.; Sen, P.

    2016-10-01

    We have designed localised surface plasmon resonance (LSPR) based fiber optic sensor. Silver nanoparticles are deposited on a few centimetre length of bare core at the middle part of plastic clad silica fiber by means of a simple and low cost laser induced nanoparticle deposition technique. The nanoparticle deposition was confirmed by TEM analysis. The nanoparticle coated fiber is used to design the sensor and the response of sensor was studied to sense fluoride impurity in water.

  14. Oxidative aliphatic C-H fluorination with manganese catalysts and fluoride ion.

    PubMed

    Liu, Wei; Huang, Xiongyi; Groves, John T

    2013-12-01

    Fluorination is a reaction that is useful in improving the chemical stability and changing the binding affinity of biologically active compounds. The protocol described here can be used to replace aliphatic, C(sp(3))-H hydrogen in small molecules with fluorine. Notably, isolated methylene groups and unactivated benzylic sites are accessible. The method uses readily available manganese porphyrin and manganese salen catalysts and various fluoride ion reagents, including silver fluoride (AgF), tetrabutylammonium fluoride and triethylamine trihydrofluoride (TREAT·HF), as the source of fluorine. Typically, the reactions afford 50-70% yield of mono-fluorinated products in one step. Two representative examples, the fragrance component celestolide and the nonsteroidal anti-inflammatory drug ibuprofen, are described; they produced useful isolated quantities (250-300 mg, ~50% yield) of fluorinated material over periods of 1-8 h. The procedures are performed in a typical fume hood using ordinary laboratory glassware. No special precautions to rigorously exclude water are required.

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

    PubMed

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

    2005-11-01

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

  16. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    DOEpatents

    Bartlett, Neil; Whalen, J. Marc; Chacon, Lisa

    2000-12-12

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

  17. Solubility characterization of airborne uranium from a uranium recycling plant.

    PubMed

    Metzger, Robert; Cole, Leslie

    2004-07-01

    Solubility profiles of uranium dusts in a uranium recycling plant were determined by performing in vitro solubility tests on breathing zone air samples conducted in all process areas of the processing plant. The recycling plant produces high density shields, closed end tubes that are punched and formed from uranium sheet metal, and high-fired uranium oxide, which is used as a catalyst. The recycled uranium is cut and melted in a vacuum furnace, and part of the molten uranium is poured into molds for further processing. Air samples were taken in process areas under normal working conditions. The dissolution rate of the uranium in a simulant solution of extracellular airway lining fluid (Gamble's solution) was then determined over the next 28 d. Airborne uranium in the oxide section of the plant was found to be highly insoluble with 99% of the uranium having a dissolution half time in excess of 100 d. The solubility of the airborne uranium in other areas of the facility was only slightly more soluble with over 90% of the airborne uranium having dissolution half times in excess of 90 d.

  18. PROCESS OF RECOVERING URANIUM

    DOEpatents

    Price, T.D.; Jeung, N.M.

    1958-06-17

    An improved precipitation method is described for the recovery of uranium from aqueous solutions. After removal of all but small amounts of Ni or Cu, and after complexing any iron present, the uranium is separated as the peroxide by adding H/sub 2/O/sub 2/. The improvement lies in the fact that the addition of H/sub 2/O/sub 2/ and consequent precipitation are carried out at a temperature below the freezing; point of the solution, so that minute crystals of solvent are present as seed crystals for the precipitation.

  19. PRODUCTION OF URANIUM TUBING

    DOEpatents

    Creutz, E.C.

    1958-04-15

    The manufacture of thin-walled uranium tubing by the hot-piercing techique is described. Uranium billets are preheated to a temperature above 780 d C. The heated billet is fed to a station where it is engaged on its external surface by three convex-surfaced rotating rollers which are set at an angle to the axis of the billet to produce a surface friction force in one direction to force the billet over a piercing mandrel. While being formed around the mandrel and before losing the desired shape, the tube thus formed is cooled by a water spray.

  20. Corrosion-resistant uranium

    DOEpatents

    Hovis, Jr., Victor M.; Pullen, William C.; Kollie, Thomas G.; Bell, Richard T.

    1983-01-01

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

  1. TREATMENT OF URANIUM SURFACES

    DOEpatents

    Slunder, C.J.

    1959-02-01

    An improved process is presented for prcparation of uranium surfaces prior to electroplating. The surfacc of the uranium to be electroplated is anodized in a bath comprising a solution of approximately 20 to 602 by weight of phosphoric acid which contains about 20 cc per liter of concentrated hydrochloric acid. Anodization is carried out for approximately 20 minutes at a current density of about 0.5 amperes per square inch at a temperature of about 35 to 45 C. The oxidic film produced by anodization is removed by dipping in strong nitric acid, followed by rinsing with water just prior to electroplating.

  2. Recovery of Uranium Fragments

    NASA Astrophysics Data System (ADS)

    James, H. R.; McElrue, D. H.; Winter, R. E.

    2002-07-01

    We describe a theory for calculating the penetration of fragments into foam. Comparisons with regular projectiles show that the drag term is similar in value to the analogous term in aerodynamics. This, plus the simple model used to describe porosity, enables the theory to be used in predicting the levels of stress present when uranium fragments are arrested in foam catchers. Consequently the theory can be used to assist in the design of catchers which will not distort uranium fragments travelling at 1-3 km/s. The theory is tested against experiments using some current designs.

  3. Corrosion-resistant uranium

    DOEpatents

    Hovis, V.M. Jr.; Pullen, W.C.; Kollie, T.G.; Bell, R.T.

    1981-10-21

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

  4. Germylmercury complex of uranium

    SciTech Connect

    Bochkarev, M.N.; Bochkarev, L.N.; Kalinina, G.S.; Razuvaev, G.A.; Sevast'yanov, V.G.

    1983-09-01

    The authors have established that metallic uranium reacts with ((C/sub 6/F/sub 5/)/sub 3/Ge)/sub 3/Hg at about 20/sup 0/C in a medium of 1,2-dimethoxyethane (DME). The reaction was complete after 3 h by the separation of metallic mercury (100 %) and by the formation of the heptakis (tris(pentafluoro-phenyl)germyl) dimercurate of uranium (((C/sub 6/F/sub 5/)/sub 3/Ge)/sub 7/Hg/sub 2/)U3DME (i), 81%. 1 reference.

  5. METHOD OF ELECTROPOLISHING URANIUM

    DOEpatents

    Walker, D.E.; Noland, R.A.

    1959-07-14

    A method of electropolishing the surface of uranium articles is presented. The process of this invention is carried out by immersing the uranium anticle into an electrolyte which contains from 35 to 65% by volume sulfuric acid, 1 to 20% by volume glycerine and 25 to 50% by volume of water. The article is made the anode in the cell and polished by electrolyzing at a voltage of from 10 to 15 volts. Discontinuing the electrolysis by intermittently withdrawing the anode from the electrolyte and removing any polarized film formed therein results in an especially bright surface.

  6. The truth about silver.

    PubMed

    Ovington, Liza G

    2004-09-01

    Interest in silver as a topical agent in wound healing is undergoing a renaissance. Having basic information regarding silver's chemical properties and potential actions in the wound bed is important to its appropriate clinical use. Such information is also relevant to the interpretation of silver's in vitro antimicrobial (antiseptic) effects, which in turn relate to issues involved in the evaluation of the clinical effects of silver in vivo. Gaining an understanding of the basic science of silver products and the different challenges inherent to in vitro versus in vivo antimicrobial evaluations will allow clinicians to address several key questions inherent when considering the use of silver as a topical antimicrobial: 1) Are there different forms of silver? 2) How does the amount of silver released into the wound environment correlate with clinical benefit? 3) How does the rate of silver release correlate with clinical benefit?

  7. Bone char with antibacterial properties for fluoride removal: Preparation, characterization and water treatment.

    PubMed

    Delgadillo-Velasco, Lorena; Hernández-Montoya, Virginia; Cervantes, Francisco J; Montes-Morán, Miguel A; Lira-Berlanga, Diana

    2017-10-01

    In the present work, it was established a new method for the preparation of bone chars with a double purpose, i.e., the removal of fluoride from water and the antibacterial character. These adsorbents were obtained by doping a commercial bone char with Ag using different reagents. The optimal conditions for the enrichment with silver were established by following the Taguchi method and using as response variable the removal of fluoride from water. Optimal bone chars were thus prepared and they were characterized using FT-IR spectroscopy, SEM/EDX analysis, adsorption isotherms of N2 at -196 °C and X-ray diffraction. All adsorbents were used in the removal of fluoride from water and the antibacterial character was assessed using the technique of total viable count employing standard solutions of Escherichia coli and drinking water. Results clearly indicated that doping of bone chars with silver provides with suitable antibacterial properties, however the fluoride adsorption capacity was not affected by the presence of Ag° on the carbon surface. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. In vitro fluoride release from a different kind of conventional and resin modified glass-ionomer cements.

    PubMed

    Selimović-Dragaš, Mediha; Hasić-Branković, Lajla; Korać, Fehim; Đapo, Nermin; Huseinbegović, Amina; Kobašlija, Sedin; Lekić, Meliha; Hatibović-Kofman, Šahza

    2013-08-01

    Fluoride release is important characteristic of glass-ionomer cements. Quantity of fluoride ions released from the glass-ionomer cements has major importance in definition of their biological activity. The objectives of this study were to define the quantity of fluoride ions released from the experimental glass-ionomer cements and to define the effect of fluoride ions released from the experimental glass-ionomer cements on their cytotoxicity. Concentrations of the fluoride ions released in the evaluated glass-ionomer cements were measured indirectly, by the fluoride-selective WTW, F500 electrode potential, combined with reference R503/D electrode. Statistical analyses of F-ion concentrations released by all glass-ionomers evaluated at two time points, after 8 and after 24 hours, show statistically higher fluoride releases from RMGICs: Vitrebond, Fuji II LC and Fuji Plus, when compared to conventional glass-ionomer cements: Fuji Triage, Fuji IX GP Fast and Ketac Silver, both after 8 and after 24 hours. Correlation coefficient between concentrations of fluoride ion released by evaluated glass-ionomer cements and cytotoxic response of UMR-106 osteoblast cell-line are relatively high, but do not reach levels of biological significance. Correlation between concentrations of fluoride ion released and cytotoxic response of NIH3T3 mouse fibroblast cell line after 8 hours is high, positive and statistically significant for conventional GICs, Fuji Triage and Fuji IX GP Fast, and RMGIC, Fuji II LC. Statistically significant Correlation coefficient between concentrations of fluoride ion released and cytotoxic response of NIH3T3 cell line after 24 hours is defined for RMGIC Fuji II LC only.

  9. RECOVERY OF URANIUM FROM PITCHBLENDE

    DOEpatents

    Ruehle, A.E.

    1958-06-24

    The decontamination of uranium from molybdenum is described. When acid solutions containing uranyl nitrate are contacted with ether for the purpose of extracting the uranium values, complex molybdenum compounds are coextracted with the uranium and also again back-extracted from the ether with the uranium. This invention provides a process for extracting uranium in which coextraction of molybdenum is avoided. It has been found that polyhydric alcohols form complexes with molybdenum which are preferentially water-soluble are taken up by the ether extractant to only a very minor degree. The preferred embodiment of the process uses mannitol, sorbitol or a mixture of the two as the complexing agent.

  10. High loading uranium fuel plate

    DOEpatents

    Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry R.

    1990-01-01

    Two embodiments of a high uranium fuel plate are disclosed which contain a meat comprising structured uranium compound confined between a pair of diffusion bonded ductile metal cladding plates uniformly covering the meat, the meat having a uniform high fuel loading comprising a content of uranium compound greater than about 45 Vol. % at a porosity not greater than about 10 Vol. %. In a first embodiment, the meat is a plurality of parallel wires of uranium compound. In a second embodiment, the meat is a dispersion compact containing uranium compound. The fuel plates are fabricated by a hot isostatic pressing process.

  11. STRIPPING OF URANIUM FROM ORGANIC EXTRACTANTS

    DOEpatents

    Crouse, D.J. Jr.

    1962-09-01

    A liquid-liquid extraction method is given for recovering uranium values from uranium-containing solutions. Uranium is removed from a uranium-containing organic solution by contacting said organic solution with an aqueous ammonium carbonate solution substantially saturated in uranium values. A uranium- containing precipitate is thereby formed which is separated from the organic and aqueous phases. Uranium values are recovered from this separated precipitate. (AE C)

  12. Water Atomization of Barium Fluoride: Calcium Fluoride for Enhanced Flow Characteristics of PS304 Feedstock Powder Blend

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.; DellaCorte, Christopher

    2003-01-01

    PS304 is a plasma spray deposited solid lubricant coating with feedstock composed of NiCr, Cr2O3, Ag, and BaF2-CaF2 powders. The effects of rounded BaF2-CaF2 particles on the gravity-fed flow characteristics of PS304 feedstock have been investigated. The BaF2-CaF2 powder was fabricated by water atomization using four sets of process parameters. Each of these powders was then characterized by microscopy and classified by screening to obtain 45 to 106 micron particles and added incrementally from 0 to 10 wt% to the other constituents of the PS304 feedstock, namely nichrome, chromia, and silver powders. The relationship between feedstock flow rate, measured with the Hall flowmeter, and concentration of fluorides was found to be linear in each case. The slopes of the lines were between those of the linear relationships previously reported using angular and spherical fluorides and were closer to the relationship predicted using the rule of mixtures. The results offer a fluoride fabrication technique potentially more cost-effective than gas atomization processes or traditional comminution processes.

  13. Effects of zinc fluoride on inhibiting dentin demineralization and collagen degradation in vitro: A comparison of various topical fluoride agents.

    PubMed

    Thanatvarakorn, Ornnicha; Islam, Md Sofiqul; Nakashima, Syozi; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

    2016-10-01

    Root caries is developed because of demineralization followed by enzymatic collagen degradation. This in vitro study aimed to examine the inhibitory efficacy of ZnF2 on dentin demineralization and collagen degradation. Bovine dentin specimens were treated either with ZnF2 or HCl-acidified ZnF2 (ZnF2/HCl) and then demineralized. Anti-demineralization efficacy was assessed by TMR as mineral loss (ΔZ). The efficacy was compared with silver diammine fluoride (SDF), KF, and acidulated phosphate fluoride (APF). For evaluating anti-collagen degradation, EDTA-demineralized dentin specimens were treated by one of four fluoride agents [SDF, APF, ZnF2/HCl, NaF] followed by collagenase challenge. The eroded depth of collagen layer in the lesion was assessed using optical microscope. ΔZ of SDF, KF, ZnF2/HCl, and APF were significantly lower compared with ZnF2 and Control (no treatment). Regarding anti-collagen degradation, SDF and ZnF2/HCl demonstrated a significant difference in the eroded depth compared with Control. Although SDF possessed higher efficacy, ZnF2/HCl might be beneficial as a staining-free agent.

  14. Fluoride glass: Crystallization, surface tension

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1988-01-01

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

  15. Do Fluoride Ions Protect Teeth?

    ERIC Educational Resources Information Center

    Parkin, Christopher

    1998-01-01

    Begins with the procedure and results from an investigation on the effect of fluoride on the reaction between eggshell (substitute teeth) and dilute ethanoic acid. Describes an elegantly modified and improvised apparatus. (DDR)

  16. Do Fluoride Ions Protect Teeth?

    ERIC Educational Resources Information Center

    Parkin, Christopher

    1998-01-01

    Begins with the procedure and results from an investigation on the effect of fluoride on the reaction between eggshell (substitute teeth) and dilute ethanoic acid. Describes an elegantly modified and improvised apparatus. (DDR)

  17. Uranium, soluble salts

    Integrated Risk Information System (IRIS)

    Uranium , soluble salts ; no CASRN Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  18. Uranium Reduction by Clostridia

    SciTech Connect

    Francis, A.J.; Dodge, Cleveland J.; Gillow, Jeffrey B.

    2006-04-05

    The FRC groundwater and sediment contain significant concentrations of U and Tc and are dominated by low pH, and high nitrate and Al concentrations where dissimilatory metal reducing bacterial activity may be limited. The presence of Clostridia in Area 3 at the FRC site has been confirmed and their ability to reduce uranium under site conditions will be determined. Although the phenomenon of uranium reduction by Clostridia has been firmly established, the molecular mechanisms underlying such a reaction are not very clear. The authors are exploring the hypothesis that U(VI) reduction occurs through hydrogenases and other enzymes (Matin and Francis). Fundamental knowledge of metal reduction using Clostridia will allow us to exploit naturally occurring processes to attenuate radionuclide and metal contaminants in situ in the subsurface. The outline for this report are as follows: (1) Growth of Clostridium sp. under normal culture conditions; (2) Fate of metals and radionuclides in the presence of Clostridia; (3) Bioreduction of uranium associated with nitrate, citrate, and lepidocrocite; and (4) Utilization of Clostridium sp. for immobilization of uranium at the FRC Area 3 site.

  19. URANIUM RECOVERY PROCESS

    DOEpatents

    Hyman, H.H.; Dreher, J.L.

    1959-07-01

    The recovery of uranium from the acidic aqueous metal waste solutions resulting from the bismuth phosphate carrier precipitation of plutonium from solutions of neutron irradiated uranium is described. The waste solutions consist of phosphoric acid, sulfuric acid, and uranium as a uranyl salt, together with salts of the fission products normally associated with neutron irradiated uranium. Generally, the process of the invention involves the partial neutralization of the waste solution with sodium hydroxide, followed by conversion of the solution to a pH 11 by mixing therewith sufficient sodium carbonate. The resultant carbonate-complexed waste is contacted with a titanated silica gel and the adsorbent separated from the aqueous medium. The aqueous solution is then mixed with sufficient acetic acid to bring the pH of the aqueous medium to between 4 and 5, whereby sodium uranyl acetate is precipitated. The precipitate is dissolved in nitric acid and the resulting solution preferably provided with salting out agents. Uranyl nitrate is recovered from the solution by extraction with an ether such as diethyl ether.

  20. URANIUM SOLVENT EXTRACTION PROCESS

    DOEpatents

    Harrington, C.D.

    1959-09-01

    A method is given for extracting uranium values from ores of high phosphate content consisting of dissolving them in aqueous nitric acid, adjusting the concentration of the aqueous solution to about 2 M with respect to nitric acid, and then contacting it with diethyl ether which has previously been made 1 M with respect to nitric acid.

  1. Uranium Location Database

    EPA Pesticide Factsheets

    A GIS compiled locational database in Microsoft Access of ~15,000 mines with uranium occurrence or production, primarily in the western United States. The metadata was cooperatively compiled from Federal and State agency data sets and enables the user to conduct geographic and analytical studies on mine impacts on the public and environment.

  2. Roessing Uranium Limited

    SciTech Connect

    1991-04-01

    The government of Namibia, celebrating the first anniversary (Marsh 21) of the country`s independence from South African rule, is looking to Roessing Uranium Limited (RUL) to improve the economic health of the country. RUL is Namibia`s largest employer, producer of one third of the country`s exports and 13 percent of its domestic product. The Roessing mine is the second largest uranium mine in the world, producing over 108 million pounds U{sub 3}O{sub 8} from 1976 through 1989, and still holding an estimated 322 million pounds in reserves. Yet Roessing is one of the lowest grade uranium deposits ever commercially exploited, with an average grade of only 0.035 w/o U{sub 3}O{sub 8}. To efficiently develop such a low-grade deposit, RUL uses extensive real-time cost analysis systems and has the highest rock production rate (ore plus waste) of any uranium mine in the world, over 300 thousand tons per day.

  3. The neurotoxicology of uranium.

    PubMed

    Dinocourt, Céline; Legrand, Marie; Dublineau, Isabelle; Lestaevel, Philippe

    2015-11-04

    The brain is a target of environmental toxic pollutants that impair cerebral functions. Uranium is present in the environment as a result of natural deposits and release by human applications. The first part of this review describes the passage of uranium into the brain, and its effects on neurological functions and cognitive abilities. Very few human studies have looked at its cognitive effects. Experimental studies show that after exposure, uranium can reach the brain and lead to neurobehavioral impairments, including increased locomotor activity, perturbation of the sleep-wake cycle, decreased memory, and increased anxiety. The mechanisms underlying these neurobehavioral disturbances are not clearly understood. It is evident that there must be more than one toxic mechanism and that it might include different targets in the brain. In the second part, we therefore review the principal mechanisms that have been investigated in experimental models: imbalance of the anti/pro-oxidant system and neurochemical and neurophysiological pathways. Uranium effects are clearly specific according to brain area, dose, and time. Nonetheless, this review demonstrates the paucity of data about its effects on developmental processes and the need for more attention to the consequences of exposure during development.

  4. Diffusion of uranium hexafluoride

    NASA Astrophysics Data System (ADS)

    Winkelmann, J.

    This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of uranium hexafluoride

  5. Modified sodium diuranate process for the recovery of uranium from uranium hexafluoride transport cylinder wash solution

    NASA Astrophysics Data System (ADS)

    Meredith, Austin Dean

    to a uranyl peroxide (UO4) precipitate product. Evaluation of operating technique, uranium recovery efficiency, and final product purity were part of each experiment. Evaluation of a technique for removing fluoride from the diuranate precipitation byproduct filtrate using granular calcite was also included at the end of the uranium recovery testing. It was observed that precipitation of sodium diuranate (SDU) was very nearly complete at a pH of 11-12, using room temperature conditions. Uranium residuals in the filtrate ranged from 3.6 - 19.6 ppm, meaning almost complete precipitation as SDU. It was postulated and then verified that a tailing reaction occurs in the SDU precipitation, which necessitates a digestion period of about 2 hours to complete the precipitation. Further, it was shown, during this phase of the process, that a partial precipitation step at pH 5.5 did not adequately separate iron contamination due to an overlap of uranium and iron precipitations at that condition. Carbonate extraction of the SDU required an extended (3-4 hours) digestion at 40°C and pH 7-8 to complete, with sodium bicarbonate found to be the preferred extractant. The carbonate extraction was also proven to successfully separate the iron contamination from the uranium. Potassium-based chemistry did produce a potassium diuranate (KDU) analogue of SDU, but the subsequent carbonate extraction using either potassium bicarbonate or potassium carbonate proved to be too difficult and was incomplete. The potassium testing was terminated at this step. The uranyl peroxide precipitation was found to operate best at pH 3.5 - 4.0, at room temperature, and required an expected, extended digestion period of 8 -10 hours. The reaction was nearly complete at those conditions, with a filtrate residual ranging from 2.4 to 36.8 ppmU. The uranyl peroxide itself was very pure, with impurity averages at a very low 0.8 ppmNa and 0.004 ppmFe. ASTM maximum levels are 20 ppmNa and 150 ppmFe. Fluoride removal

  6. UV-Shifted Durable Silver Coating for Astronomical Mirrors

    SciTech Connect

    Thomas, N.L.; Wolfe, J.

    2000-06-01

    Silver has the highest reflectance of all of the metals, but it tarnishes in the presence of sulfides, chlorides, and oxides in the atmosphere. Also, the silver reflectance is very low at wavelengths below 400 nm making aluminum more desirable mirror coating for the UV region. They have found a way to prevent silver tarnishing by sandwiching the silver layer between two thin layers of NiCrN{sub x}, and to extend the metal's high reflectance down to 200 nm by depositing the (thin) Ag layer on top of Al. Thus, the uv is transmitted through the thin Ag layer below 400 nm wavelength, and is reflected from the Al layer underneath. This UV-shifted durable coating provides a valuable alternative to the aluminum coating for telescope mirror coatings where high throughput and durability are important considerations. The throughput for a telescope with, say, six reflections from silver coatings is (0.97){sup 6} = 83% compared to (0.92){sup 6} = 60% for aluminum coatings, or 28% less. The use of silver coatings allows more photons to be collected by primary mirror. Aluminum also has a reflectance dip at 850 nm caused by inter-band transitions which is eliminated by placing the thin Ag layer on top. This paper describes a non-tarnishing silver coating having high reflectance down into the UV region. The average specular reflectance is 70%-97% in the near-UV, 95%-99% in the visible region, and {ge} 99% in the infrared region covering the total wavelength range 200 nm to 10,000 nm. Figure 1 compares the reflectance of the UVHR-LLNL silver coating to bare silver and aluminum over-coated with magnesium fluoride over the wavelength range 300 nm to 2000 nm.

  7. Uranium from seawater

    SciTech Connect

    Gregg, D.; Folkendt, M.

    1982-09-21

    A novel process for recovering uranium from seawater is proposed and some of the critical technical parameters are evaluated. The process, in summary, consists of two different options for contacting adsorbant pellets with seawater without pumping the seawater. It is expected that this will reduce the mass handling requirements, compared to pumped seawater systems, by a factor of approximately 10/sup 5/, which should also result in a large reduction in initial capital investment. Activated carbon, possibly in combination with a small amount of dissolved titanium hydroxide, is expected to be the preferred adsorbant material instead of the commonly assumed titanium hydroxide alone. The activated carbon, after exposure to seawater, can be stripped of uranium with an appropriate eluant (probably an acid) or can be burned for its heating value (possible in a power plant) leaving the uranium further enriched in its ash. The uranium, representing about 1% of the ash, is then a rich ore and would be recovered in a conventional manner. Experimental results have indicated that activated carbon, acting alone, is not adequately effective in adsorbing the uranium from seawater. We measured partition coefficients (concentration ratios) of approximately 10/sup 3/ in seawater instead of the reported values of 10/sup 5/. However, preliminary tests carried out in fresh water show considerable promise for an extraction system that uses a combination of dissolved titanium hydroxide (in minute amounts) which forms an insoluble compound with the uranyl ion, and the insoluble compound then being sorbed out on activated carbon. Such a system showed partition coefficients in excess of 10/sup 5/ in fresh water. However, the system was not tested in seawater.

  8. PRODUCTION OF URANIUM METAL BY CARBON REDUCTION

    DOEpatents

    Holden, R.B.; Powers, R.M.; Blaber, O.J.

    1959-09-22

    The preparation of uranium metal by the carbon reduction of an oxide of uranium is described. In a preferred embodiment of the invention a charge composed of carbon and uranium oxide is heated to a solid mass after which it is further heated under vacuum to a temperature of about 2000 deg C to produce a fused uranium metal. Slowly ccoling the fused mass produces a dendritic structure of uranium carbide in uranium metal. Reacting the solidified charge with deionized water hydrolyzes the uranium carbide to finely divide uranium dioxide which can be separated from the coarser uranium metal by ordinary filtration methods.

  9. In-SEM Raman microspectroscopy coupled with EDX--a case study of uranium reference particles.

    PubMed

    Stefaniak, Elżbieta A; Pointurier, Fabien; Marie, Olivier; Truyens, Jan; Aregbe, Yetunde

    2014-02-07

    Information about the molecular composition of airborne uranium-bearing particles may be useful as an additional tool for nuclear safeguards. In order to combine the detection of micrometer-sized particles with the analysis of their molecular forms, we used a hybrid system enabling Raman microanalysis in high vacuum inside a SEM chamber (SEM-SCA system). The first step involved an automatic scan of a sample to detect and save coordinates of uranium particles, along with X-ray microanalysis. In the second phase, the detected particles were relocated in a white light image and subjected to Raman microanalysis. The consecutive measurements by the two beams showed exceptional fragility of uranium particles, leading to their ultimate damage and change of uranium oxidation state. We used uranium reference particles prepared by hydrolysis of uranium hexafluoride to test the reliability of the Raman measurements inside the high vacuum. The results achieved by the hybrid system were verified by using a standalone Raman microspectrometer. When deposited on exceptionally smooth substrates, uranyl fluoride particles smaller than 1000 nm could successfully be analyzed with the SEM-SCA system.

  10. Uranium control in phosphogypsum. [In wet-process phosphoric acid production

    SciTech Connect

    Hurst, F.J.; Arnold, W.D.

    1980-01-01

    In wet-process phosphoric acid plants, both previous and recent test results show that uranium dissolution from phosphate rock is significantly higher when the rock is acidulated under oxidizing conditions than under reducing conditions. Excess sulfate and excess fluoride further enhance the distribution of uranium to the cake. Apparently the U(IV) present in the crystal lattice of the apatite plus that formed by reduction of U(IV) by FE(II) during acidulation is trapped or carried into the crystal lattice of the calcium sulfate crystals as they form and grow. The amount of uranium that distributes to hemihydrate filter cake is up to seven times higher than the amount that distributes to the dihydrate cake. About 60% of the uranium in hemihydrate cakes can be readily leached after hydration of the cake, but the residual uranium (20 to 30%) is very difficult to remove economically. Much additional research is needed to develop methods for minimizing uranium losses to calcium filter cakes.

  11. The Silver Halides

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  12. Colloidal Silver Products

    MedlinePlus

    ... can be dangerous to your health. What the Science Says About the Safety and Side Effects of ... homemade and commercial colloidal silver products. What the Science Says About the Effectiveness of Colloidal Silver Scientific ...

  13. TRANSITION STATE FOR THE GAS-PHASE REACTION OF URANIUM HEXAFLUORIDE WITH WATER

    SciTech Connect

    Garrison, S; James Becnel, J

    2008-03-18

    Density Functional Theory and small-core, relativistic pseudopotentials were used to look for symmetric and asymmetric transitions states of the gas-phase hydrolysis reaction of uranium hexafluoride, UF{sub 6}, with water. At the B3LYP/6-31G(d,p)/SDD level, an asymmetric transition state leading to the formation of a uranium hydroxyl fluoride, U(OH)F{sub 5}, and hydrogen fluoride was found with an energy barrier of +77.3 kJ/mol and an enthalpy of reaction of +63.0 kJ/mol (both including zero-point energy corrections). Addition of diffuse functions to all atoms except uranium led to only minor changes in the structure and relative energies of the reacting complex and transition state. However, a significant change in the product complex structure was found, significantly reducing the enthalpy of reaction to +31.9 kJ/mol. Similar structures and values were found for PBE0 and MP2 calculations with this larger basis set, supporting the B3LYP results. No symmetric transition state leading to the direct formation of uranium oxide tetrafluoride, UOF{sub 4}, was found, indicating that the reaction under ambient conditions likely includes several more steps than the mechanisms commonly mentioned. The transition state presented here appears to be the first published transition state for the important gas-phase reaction of UF{sub 6} with water.

  14. Transition state for the gas-phase reaction of uranium hexafluoride with water.

    PubMed

    Garrison, Stephen L; Becnel, James M

    2008-06-19

    Density functional theory and small-core, relativistic pseudopotentials were used to look for symmetric and asymmetric transition states of the gas-phase hydrolysis reaction of uranium hexafluoride, UF 6, with water. At the B3LYP/6-31G(d,p)/SDD level, an asymmetric transition state leading to the formation of a uranium hydroxyl fluoride, U(OH)F 5, and hydrogen fluoride was found with an energy barrier of +77.3 kJ/mol and an enthalpy of reaction of +63.0 kJ/mol (both including zero-point energy corrections). Addition of diffuse functions to all atoms except uranium led to only minor changes in the structures and relative energies of the reacting complex and transition state. However, a significant change in the structure of the product complex was found, significantly reducing the enthalpy of reaction to +31.9 kJ/mol. Similar structures and values were found for PBE0 and MP2 calculations with this larger basis set, supporting the B3LYP results. No symmetric transition state leading to the direct formation of uranium oxide tetrafluoride, UOF 4, was found, indicating that the reaction under ambient conditions likely includes several more steps than the mechanisms commonly mentioned. The transition state presented here appears to be the first published transition state for the important gas-phase reaction of UF 6 with water.

  15. Method of preparation of uranium nitride

    DOEpatents

    Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

    2013-07-09

    Method for producing terminal uranium nitride complexes comprising providing a suitable starting material comprising uranium; oxidizing the starting material with a suitable oxidant to produce one or more uranium(IV)-azide complexes; and, sufficiently irradiating the uranium(IV)-azide complexes to produce the terminal uranium nitride complexes.

  16. Chemical aspects of the trapping and recovery of uranium hexafluoride and fluorine during remediation activities

    SciTech Connect

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

    1996-10-01

    Decontamination and decommission activities related to the Molten Salt Reactor Experiment (MSRE) involve the trapping and recovery of radiolitically generated uranium hexafluoride and fluorine. Although fission product radiolysis was known to generate F{sub 2}, the formation of UF{sub 6} and its transport from the fuel salt was unexpected. Some of these gaseous radiolysis products have been moving through the gas piping to a charcoal bed since the reactor was shut down in 1969. Current and planned remediation and clean-up activities involve the trapping of the gaseous products, deactivation and treatment of the activated charcoal bed, stabilization and reconditioning of the fuel salt, and recovery of the uranium. The chemical aspects of these processes, including radiolytic generation mechanisms, reactions between uranium hexafluoride and fluorine and trapping materials such as activated charcoal, activated alumina, and sodium fluoride, along with the analytical techniques used for the characterization of the materials and process control will be described.

  17. Irradiation test of tungsten clad uranium carbide-zirconium carbide ((U,Zr)C) specimens for thermionic reactor application at conditions conductive to long-term performance

    NASA Technical Reports Server (NTRS)

    Creagh, J. W. R.; Smith, J. R.

    1973-01-01

    Uranium carbide fueled, thermionic emitter configurations were encapsulated and irradiated. One capsule contained a specimen clad with fluoride derived chemically vapor deposited (CVD) tungsten. The other capsule used a duplex clad specimen consisting of chloride derived on floride derived CVD tungsten. Both fuel pins were 16 millimeters in diameter and contained a 45.7-millimeter length of fuel.

  18. Polyimides Containing Silver Trifluoroacetylacetonate

    NASA Technical Reports Server (NTRS)

    Stoakley, Diane M.; St. Clair, Anne K.; Rancourt, James D.; Taylor, Larry T.; Caplan, Maggie L.

    1994-01-01

    Mechanically strong, flexible, thermally stable, electrically conductive films and coatings suitable for use in electronics industry made by incorporating silver trifluoroacetylacetonate into linear aromatic condensation polyimides. In experimental films, most successful combinations of flexibility and conductivity obtained by use of 1:1, 1:1.74, and 1:2 mole ratios of silver trifluoroacetylacetonate per polyimide repeat unit. Other concentrations of silver trifluoroacetylacetonate used with different heat-treatment schedules to obtain conductive silver-impregnated films.

  19. Immobilization of silver nanoparticles synthesized using Curcuma longa tuber powder and extract on cotton cloth for bactericidal activity.

    PubMed

    Sathishkumar, Muthuswamy; Sneha, Krishnamurthy; Yun, Yeoung-Sang

    2010-10-01

    The present study reports the synthesis of silver (Ag) nanoparticles from silver precursor using plant biomaterials, Curcuma longa tuber powder and extract. Water-soluble organics present in the plant materials were mainly responsible for the reduction of silver ions to nano-sized silver particles. pH played a major role in size control of the particles. Silver nanoparticle synthesis was higher in tuber extract compared to powder, which was attributed to the large and easy availability of the reducing agents in the extract. Zeta potential studies showed that the surface charge of the formed nanoparticles was highly negative. The minimum bactericidal concentration (MBC) for Escherichia coli BL-21 strain was found to be 50 mg/L. Immobilization of silver nanoparticles on cotton cloth using sterile water showed better bactericidal activity when compared to polyvinylidene fluoride (PVDF) immobilized cloth, but on consecutive washing the activity reduced drastically in sterile water immobilized cloth. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Fluoride bioavailability in saliva and plaque

    PubMed Central

    2012-01-01

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

  1. Studies of fluoride varnishes in Finland.

    PubMed

    Seppä, L

    1991-01-01

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

  2. Health effects of groundwater fluoride contamination.

    PubMed

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

    2009-04-01

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

  3. Fluoride content of tank water in Australia.

    PubMed

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

    2014-06-01

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

  4. Chronic fluoride toxicity: dental fluorosis.

    PubMed

    Denbesten, Pamela; Li, Wu

    2011-01-01

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

  5. Chronic Fluoride Toxicity: Dental Fluorosis

    PubMed Central

    DenBesten, Pamela; Li, Wu

    2012-01-01

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

  6. Acute toxicity of ingested fluoride.

    PubMed

    Whitford, Gary Milton

    2011-01-01

    This chapter discusses the characteristics and treatment of acute fluoride toxicity as well as the most common sources of overexposure, the doses that cause acute toxicity, and factors that can influence the clinical outcome. Cases of serious systemic toxicity and fatalities due to acute exposures are now rare, but overexposures causing toxic signs and symptoms are not. The clinical course of systemic toxicity from ingested fluoride begins with gastric signs and symptoms, and can develop with alarming rapidity. Treatment involves minimizing absorption by administering a solution containing calcium, monitoring and managing plasma calcium and potassium concentrations, acid-base status, and supporting vital functions. Approximately 30,000 calls to US poison control centers concerning acute exposures in children are made each year, most of which involve temporary gastrointestinal effects, but others require medical treatment. The most common sources of acute overexposures today are dental products - particularly dentifrices because of their relatively high fluoride concentrations, pleasant flavors, and their presence in non-secure locations in most homes. For example, ingestion of only 1.8 ounces of a standard fluoridated dentifrice (900-1,100 mg/kg) by a 10-kg child delivers enough fluoride to reach the 'probably toxic dose' (5 mg/kg body weight). Factors that may influence the clinical course of an overexposure include the chemical compound (e.g. NaF, MFP, etc.), the age and acid-base status of the individual, and the elapsed time between exposure and the initiation of treatment. While fluoride has well-established beneficial dental effects and cases of serious toxicity are now rare, the potential for toxicity requires that fluoride-containing materials be handled and stored with the respect they deserve. Copyright © 2011 S. Karger AG, Basel.

  7. Method of preparing uranium nitride or uranium carbonitride bodies

    DOEpatents

    Wilhelm, Harley A.; McClusky, James K.

    1976-04-27

    Sintered uranium nitride or uranium carbonitride bodies having a controlled final carbon-to-uranium ratio are prepared, in an essentially continuous process, from U.sub.3 O.sub.8 and carbon by varying the weight ratio of carbon to U.sub.3 O.sub.8 in the feed mixture, which is compressed into a green body and sintered in a continuous heating process under various controlled atmospheric conditions to prepare the sintered bodies.

  8. Method for fabricating uranium foils and uranium alloy foils

    DOEpatents

    Hofman, Gerard L.; Meyer, Mitchell K.; Knighton, Gaven C.; Clark, Curtis R.

    2006-09-05

    A method of producing thin foils of uranium or an alloy. The uranium or alloy is cast as a plate or sheet having a thickness less than about 5 mm and thereafter cold rolled in one or more passes at substantially ambient temperatures until the uranium or alloy thereof is in the shape of a foil having a thickness less than about 1.0 mm. The uranium alloy includes one or more of Zr, Nb, Mo, Cr, Fe, Si, Ni, Cu or Al.

  9. RECOVERY OF URANIUM FROM ZIRCONIUM-URANIUM NUCLEAR FUELS

    DOEpatents

    Gens, T.A.

    1962-07-10

    An improvement was made in a process of recovering uranium from a uranium-zirconium composition which was hydrochlorinated with gsseous hydrogen chloride at a temperature of from 350 to 800 deg C resulting in volatilization of the zirconium, as zirconium tetrachloride, and the formation of a uranium containing nitric acid insoluble residue. The improvement consists of reacting the nitric acid insoluble hydrochlorination residue with gaseous carbon tetrachloride at a temperature in the range 550 to 600 deg C, and thereafter recovering the resulting uranium chloride vapors. (AEC)

  10. 49 CFR 173.163 - Hydrogen fluoride.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  11. Effect of three fluoride compounds on the growth of oral normal and tumor cells.

    PubMed

    Acra, Alejandro Mena; Sakagami, Hiroshi; Matsuta, Tomohiko; Adachi, Kazunori; Otsuki, Sumiko; Nakajima, Hiroshi; Koh, Teho; Machino, Mamoru; Ogihara, Takashi; Watanabe, Koji; Watanabe, Shigeru; Salgado, Angel Visoso; Bastida, Norma M Montiel

    2012-01-01

    Comparative study of the growth inhibition by different types of fluoride compounds used in dentistry has been limited. We investigated the effects of sodium fluoride (NaF), diammine silver fluoride [Ag(NH3)2F] and 5-fluorouracil (5-FU) on the growth of eleven human normal and tumor cells in total. Viable cell number was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction was evaluated by caspase-3 activation and DNA fragmentation. Fluoride was determined using a fluoride-specific electrode. All compounds had little or no growth stimulating effect (hormesis) on all cells. Ag(NH3)2F exhibited the highest cytotoxicity towards both normal and tumor cells. 5-FU had the selective cytostatic activity towards oral squamous cell carcinoma cell lines, whereas NaF was selectively cytotoxic towards glioblastoma cell lines. None of the compounds induced internucleosomal DNA fragmentation and only 5-FU induced slight activation of caspase-3 in an oral squamous cell carcinoma cell line (HSC-2). Cytotoxicity of fluoride compounds was not reduced by superoxide dismutase and catalase, reducing the possibility of the involvement of reactive oxygen species in the mechanism of action. Approximately 0.01-0.09% initially added NaF was recovered from the cells, whereas the cellular uptake of Ag(NH3)2F and 5-FU was below the detection limit. Cytotoxicity of fluoride compounds may not be directly linked to their tumor specificity nor to their apoptosis-inducing activity.

  12. The double effects of silver nanoparticles on the PVDF membrane: Surface hydrophilicity and antifouling performance

    NASA Astrophysics Data System (ADS)

    Li, Jian-Hua; Shao, Xi-Sheng; Zhou, Qing; Li, Mi-Zi; Zhang, Qi-Qing

    2013-01-01

    In this study, silver nanoparticles were used to endow poly(vinylidene fluoride) (PVDF) membrane with excellent surface hydrophilicity and outstanding antifouling performance. Silver nanoparticles were successfully immobilized onto PVDF membrane surface under the presence of poly(acrylic acid) (PAA). The double effects of silver nanoparticles on PVDF membrane, i.e., surface hydrophilicity and anti-fouling performance, were systematically investigated. Judging from result of water static contact measurement, silver nanoparticles had provided a significant improvement in PVDF membrane surface hydrophilicity. And the possible explanation on the improvement of PVDF membrane surface hydrophilicity with silver nanoparticles was firstly proposed in this study. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membrane. Flux recovery ratio (FRR) increased about 40% after the presence of silver nanoparticles on the PVDF membrane surface, elucidating the anti-organic fouling performance of PVDF membrane was elevated by silver nanoparticles. Simultaneously, anti-bacterial test confirmed that PVDF membrane showed superior anti-biofouling activity because of silver nanoparticles. The above-mentioned results clarified that silver nanoparticles can endow PVDF membrane with both excellent surface hydrophilicity and outstanding antifouling performance in this study.

  13. [Natural fluorides. The distinction between technically produced and naturally occurring fluorides in caries prophylaxis].

    PubMed

    Newesely, H

    1977-06-01

    In the controversial discussion of the bio-availability of fluoride in caries prophylaxis by fluoridation, fluorides coming from the geochemical circulation to the biochemical circulation are sometimes differentiated from synthetic fluorides introduced into fluoride medication. The question as to whether such a differentiation is essential can be answered from the physical-chemical point of view. This requires a wide field of scientific research starting with geochemistry and the knowledge of fluoride deposits, sedimentology, hydrology, technology of inorganic and organic fluorine compounds, thermodynamics of dissolved fluorides, up to biocrystallography and biochemistry of fluorine.

  14. PROCESS FOR PRODUCING URANIUM TETRAFLUORIDE

    DOEpatents

    Harvey, B.G.

    1954-09-14

    >This patent relates to improvements in the method for producing uranium tetrafluoride by treating an aqueous solutlon of a uranyl salt at an elevated temperature with a reducing agent effective in acld solutlon in the presence of hydrofluoric acid. Uranium tetrafluoride produced this way frequentiy contains impurities in the raw material serving as the source of uranium. Uranium tetrafluoride much less contaminated with impurities than when prepared by the above method can be prepared from materials containing such impurities by first adding a small proportion of reducing agent so as to cause a small fraction, for example 1 to 5% of the uranium tetrafluoride to be precipitated, rejecting such precipitate, and then precipitating and recovering the remainder of the uranium tetrafluoride.

  15. ELECTROLYSIS OF THORIUM AND URANIUM

    DOEpatents

    Hansen, W.N.

    1960-09-01

    An electrolytic method is given for obtaining pure thorium, uranium, and thorium-uranium alloys. The electrolytic cell comprises a cathode composed of a metal selected from the class consisting of zinc, cadmium, tin, lead, antimony, and bismuth, an anode composed of at least one of the metals selected from the group consisting of thorium and uranium in an impure state, and an electrolyte composed of a fused salt containing at least one of the salts of the metals selected from the class consisting of thorium, uranium. zinc, cadmium, tin, lead, antimony, and bismuth. Electrolysis of the fused salt while the cathode is maintained in the molten condition deposits thorium, uranium, or thorium-uranium alloys in pure form in the molten cathode which thereafter may be separated from the molten cathode product by distillation.

  16. Concept Feasibility Report for Electroplating Zirconium onto Uranium Foil - Year 2

    SciTech Connect

    Coffey, Greg W.; Meinhardt, Kerry D.; Joshi, Vineet V.; Pederson, Larry R.; Lavender, Curt A.; Burkes, Douglas

    2015-03-01

    The Fuel Fabrication Capability within the U.S. High Performance Research Reactor Conversion Program is funded through the National Nuclear Security Administration (NNSA) NA-26 (Office of Material Management and Minimization). An investigation was commissioned to determine the feasibility of using electroplating techniques to apply a coating of zirconium onto depleted uranium/molybdenum alloy (U-10Mo). Electroplating would provide an alternative method to the existing process of hot roll-bonding zirconium foil onto the U-10Mo fuel foil during the fabrication of fuel elements for high-performance research reactors. The objective of this research was to develop a reproducible and scalable plating process that will produce a uniform, 25 μm thick zirconium metal coating on U-10Mo foil. In previous work, Pacific Northwest National Laboratory (PNNL) established a molten salt electroplating apparatus and protocol to plate zirconium metal onto molybdenum foil (Coffey 2015). During this second year of the research, PNNL furthered this work by moving to the U-10Mo alloy system (90 percent uranium:10 percent molybdenum). The original plating apparatus was disassembled and re-assembled in a laboratory capable of handling low-level radioactive materials. Initially, the work followed the previous year’s approach, and the salt bath composition was targeted at the eutectic composition (LiF:NaF:ZrF4 = 26:37:37 mol%). Early results indicated that the formation of uranium fluoride compounds would be problematic. Other salt bath compositions were investigated in order to eliminate the uranium fluoride production (LiF:NaF = 61:39 mol% and LiF:NaF:KF = 46.5:11.5:42 mol% ). Zirconium metal was used as the crucible for the molten salt. Three plating methods were used—isopotential, galvano static, and pulsed plating. The molten salt method for zirconium metal application provided high-quality plating on molybdenum in PNNL’s previous work. A key advantage of this approach is that

  17. Uranium Mines and Mills Location Database

    EPA Pesticide Factsheets

    The Uranium Mines and Mills location database identifies and shows the location of active and inactive uranium mines and mills, as well as mines which principally produced other minerals, but were known to have uranium in the ore.

  18. PROCESS FOR REMOVING NOBLE METALS FROM URANIUM

    DOEpatents

    Knighton, J.B.

    1961-01-31

    A pyrometallurgical method is given for purifying uranium containing ruthenium and palladium. The uranium is disintegrated and oxidized by exposure to air and then the ruthenium and palladium are extracted from the uranium with molten zinc.

  19. Radiolytic effects on fluoride impurities in a triuranium octaoxide matrix

    NASA Astrophysics Data System (ADS)

    Icenhour, Alan Scott

    The safe handling and storage of radioactive materials require an understanding of the effects of radiolysis on those materials. Radiolysis may result in the production of gases (e.g., corrosives) or pressures that are deleterious to storage containers. A study has been performed to address these concerns as they relate to the radiolysis of residual fluoride compounds in uranium oxides. The interactions of radiation with crystalline solids, based on the bonding characteristics of the crystal, were described. Samples of UO 2F2O·xH2O and U3 O8, (with ˜1.4 wt % fluorine content) were irradiated in a 60Co source and in spent nuclear fuel (SNF) elements from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Container pressures were monitored throughout the irradiations, and gas and solid samples were analyzed after the irradiations. The irradiation of UO2F 2·xH2O produced O2---with G(O2)-values ranging from 0.007 to 0.03 molecules O2 produced per 100 eV. Neither F2 nor HF was produced by the irradiations. Chemical analysis of solid samples showed that some of the uranium was reduced from U(VI) to U(IV). A saturation damage limit for the UO2F 2-xH2O was demonstrated by using the HFIR SNF elements, and the limit was found to be 7--9% (at ˜108 rad/h). It is shown that the covalently bonded oxygen is more susceptible to radiation damage than is the ionically bonded fluorine. Irradiation of U3O 8 (with ˜1.4 wt % fluorine content) resulted in neither gas production nor a pressure increase. These experiments led to the conclusion that U 3O8 is safe during long-term storage from overpressurization and the production of corrosives caused by gamma radiolysis of residual fluorides.

  20. FORMATION OF URANIUM PRECIPITATES

    DOEpatents

    Googin, J.M. Jr.

    1959-03-17

    A method is described for precipitation of uranium peroxide from uranium- containing solutions so as to obtain larger aggregates which facilitates washings decantations filtrations centrifugations and the like. The desired larger aggregate form is obtained by maintaining the pH of the solution in the approximate range of 1 to 3 and the temperature at about 25 deg C or below while carrytng out the precipitation. Then prior to removal of the precipitate a surface active sulfonated bicarboxyacids such as di-octyl sodium sulfo-succinates is incorporated in an anount of the order of 0.01 to 0.05 percent by weights and the slurry is allowed to ripen for about one-half hour at a temperatare below 10 deg C.

  1. METHOD OF PRODUCING URANIUM

    DOEpatents

    Foster, L.S.; Magel, T.T.

    1958-05-13

    A modified process is described for the production of uranium metal by means of a bomb reduction of UF/sub 4/. Difficulty is sometimes experienced in obtaining complete separation of the uranium from the slag when the process is carried out on a snnall scale, i.e., for the production of 10 grams of U or less. Complete separation may be obtained by incorporating in the reaction mixture a quantity of MnCl/sub 2/, so that this compound is reduced along with the UF/sub 4/ . As a result a U--Mn alloy is formed which has a melting point lower than that of pure U, and consequently the metal remains molten for a longer period allowing more complete separation from the slag.

  2. Instabilities in uranium plasma.

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1971-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P equal to about .00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  3. Instabilities in uranium plasma.

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1971-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P equal to about .00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  4. Optimization of silver-dielectric-silver nanoshell for sensing applications

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  5. Optimization of silver-dielectric-silver nanoshell for sensing applications

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-01

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  6. METHOD OF JACKETING URANIUM BODIES

    DOEpatents

    Maloney, J.O.; Haines, E.B.; Tepe, J.B.

    1958-08-26

    An improved process is presented for providing uranium slugs with thin walled aluminum jackets. Since aluminum has a slightiy higher coefficient of thermal expansion than does uraaium, both uranium slugs and aluminum cans are heated to an elevated temperature of about 180 C, and the slug are inserted in the cans at that temperature. During the subsequent cooling of the assembly, the aluminum contracts more than does the uranium and a tight shrink fit is thus assured.

  7. PROCESS FOR PREPARING URANIUM METAL

    DOEpatents

    Prescott, C.H. Jr.; Reynolds, F.L.

    1959-01-13

    A process is presented for producing oxygen-free uranium metal comprising contacting iodine vapor with crude uranium in a reaction zone maintained at 400 to 800 C to produce a vaporous mixture of UI/sub 4/ and iodine. Also disposed within the maction zone is a tungsten filament which is heated to about 1600 C. The UI/sub 4/, upon contacting the hot filament, is decomposed to molten uranium substantially free of oxygen.

  8. METHOD OF DISSOLVING URANIUM METAL

    DOEpatents

    Slotin, L.A.

    1958-02-18

    This patent relates to an economicai means of dissolving metallic uranium. It has been found that the addition of a small amount of perchloric acid to the concentrated nitric acid in which the uranium is being dissolved greatly shortens the time necessary for dissolution of the metal. Thus the use of about 1 or 2 percent of perchioric acid based on the weight of the nitric acid used, reduces the time of dissolution of uranium by a factor of about 100.

  9. WELDED JACKETED URANIUM BODY

    DOEpatents

    Gurinsky, D.H.

    1958-08-26

    A fuel element is presented for a neutronic reactor and is comprised of a uranium body, a non-fissionable jacket surrounding sald body, thu jacket including a portion sealed by a weld, and an inclusion in said sealed jacket at said weld of a fiux having a low neutron capture cross-section. The flux is provided by combining chlorine gas and hydrogen in the intense heat of-the arc, in a "Heliarc" welding muthod, to form dry hydrochloric acid gas.

  10. Uranium price forecasting methods

    SciTech Connect

    Fuller, D.M.

    1994-03-01

    This article reviews a number of forecasting methods that have been applied to uranium prices and compares their relative strengths and weaknesses. The methods reviewed are: (1) judgemental methods, (2) technical analysis, (3) time-series methods, (4) fundamental analysis, and (5) econometric methods. Historically, none of these methods has performed very well, but a well-thought-out model is still useful as a basis from which to adjust to new circumstances and try again.

  11. METHOD FOR RECOVERING URANIUM FROM OILS

    DOEpatents

    Gooch, L.H.

    1959-07-14

    A method is presented for recovering uranium from hydrocarbon oils, wherein the uranium is principally present as UF/sub 4/. According to the invention, substantially complete removal of the uranium from the hydrocarbon oil may be effected by intimately mixing one part of acetone to about 2 to 12 parts of the hydrocarbon oil containing uranium and separating the resulting cake of uranium from the resulting mixture. The uranium in the cake may be readily recovered by burning to the oxide.

  12. Depleted Uranium in Repositories

    SciTech Connect

    Haire, M.J.; Croff, A.G.

    1997-12-31

    For uranium to be useful in most fission nuclear reactors, it must be enriched (i.e. the concentration of the fissile isotope 235U must be increased). Therefore, depleted uranium (DU)-uranium which has less than naturally occurring concentrations of 235U-is a co-product of the enrichment process. Four to six tons of DU exist for every ton of fresh light water reactor fuel. There were 407,006 MgU 407,000 metric tons (t) of DU stored on U.S. Department of Energy (DOE) sites as of July 1993. If this DU were to be declared surplus, converted to a stable oxide form, and emplaced in a near surface disposal facility, the costs are estimated to be several billion dollars. However, the U.S. Nuclear Regulatory Commission has stated that near surface disposal of large quantities of DU tails is not appropriate. Thus, there is the possibility that disposition via disposal will be in a deep geological repository. One alternative that may significantly reduce the cost of DU disposition is to use it beneficially. In fact, DOE has begun the Beneficial Uses of DU Project to identify large scale uses of DU and to encourage its reuse. Several beneficial uses, many of which involve applications in the repository per se or in managing the wastes to go into the repository, are discussed in this report.

  13. Sputtering of uranium

    NASA Technical Reports Server (NTRS)

    Gregg, R.; Tombrello, T. A.

    1978-01-01

    Results are presented for an experimental study of the sputtering of U-235 atoms from foil targets by hydrogen, helium, and argon ions, which was performed by observing tracks produced in mica by fission fragments following thermal-neutron-induced fission. The technique used allowed measurements of uranium sputtering yields of less than 0.0001 atom/ion as well as yields involving the removal of less than 0.01 monolayer of the uranium target surface. The results reported include measurements of the sputtering yields for 40-120-keV protons, 40-120-keV He-4(+) ions, and 40- and 80-keV Ar-40(+) ions, the mass distribution of chunks emitted during sputtering by the protons and 80-keV Ar-40(+) ions, the total chunk yield during He-4(+) sputtering, and some limited data on molecular sputtering by H2(+) and H3(+). The angular distribution of the sputtered uranium is discussed, and the yields obtained are compared with the predictions of collision cascade theory.

  14. The Toxicity of Depleted Uranium

    PubMed Central

    Briner, Wayne

    2010-01-01

    Depleted uranium (DU) is an emerging environmental pollutant that is introduced into the environment primarily by military activity. While depleted uranium is less radioactive than natural uranium, it still retains all the chemical toxicity associated with the original element. In large doses the kidney is the target organ for the acute chemical toxicity of this metal, producing potentially lethal tubular necrosis. In contrast, chronic low dose exposure to depleted uranium may not produce a clear and defined set of symptoms. Chronic low-dose, or subacute, exposure to depleted uranium alters the appearance of milestones in developing organisms. Adult animals that were exposed to depleted uranium during development display persistent alterations in behavior, even after cessation of depleted uranium exposure. Adult animals exposed to depleted uranium demonstrate altered behaviors and a variety of alterations to brain chemistry. Despite its reduced level of radioactivity evidence continues to accumulate that depleted uranium, if ingested, may pose a radiologic hazard. The current state of knowledge concerning DU is discussed. PMID:20195447

  15. THERMAL DECOMPOSITION OF URANIUM COMPOUNDS

    DOEpatents

    Magel, T.T.; Brewer, L.

    1959-02-10

    A method is presented of preparing uranium metal of high purity consisting contacting impure U metal with halogen vapor at between 450 and 550 C to form uranium halide vapor, contacting the uranium halide vapor in the presence of H/sub 2/ with a refractory surface at about 1400 C to thermally decompose the uranium halides and deposit molten U on the refractory surface and collecting the molten U dripping from the surface. The entire operation is carried on at a sub-atmospheric pressure of below 1 mm mercury.

  16. Uranium droplet core nuclear rocket

    NASA Technical Reports Server (NTRS)

    Anghaie, Samim

    1991-01-01

    Uranium droplet nuclear rocket is conceptually designed to utilize the broad temperature range ofthe liquid phase of metallic uranium in droplet configuration which maximizes the energy transfer area per unit fuel volume. In a baseline system dissociated hydrogen at 100 bar is heated to 6000 K, providing 2000 second of Isp. Fission fragments and intense radian field enhance the dissociation of molecular hydrogen beyond the equilibrium thermodynamic level. Uranium droplets in the core are confined and separated by an axisymmetric vortex flow generated by high velocity tangential injection of hydrogen in the mid-core regions. Droplet uranium flow to the core is controlled and adjusted by a twin flow nozzle injection system.

  17. Uranium droplet core nuclear rocket

    NASA Technical Reports Server (NTRS)

    Anghaie, Samim

    1991-01-01

    Uranium droplet nuclear rocket is conceptually designed to utilize the broad temperature range ofthe liquid phase of metallic uranium in droplet configuration which maximizes the energy transfer area per unit fuel volume. In a baseline system dissociated hydrogen at 100 bar is heated to 6000 K, providing 2000 second of Isp. Fission fragments and intense radian field enhance the dissociation of molecular hydrogen beyond the equilibrium thermodynamic level. Uranium droplets in the core are confined and separated by an axisymmetric vortex flow generated by high velocity tangential injection of hydrogen in the mid-core regions. Droplet uranium flow to the core is controlled and adjusted by a twin flow nozzle injection system.

  18. SEPARATION OF THORIUM FROM URANIUM

    DOEpatents

    Bane, R.W.

    1959-09-01

    A description is given for the separation of thorium from uranium by forming an aqueous acidic solution containing ionic species of thorium, uranyl uranium, and hydroxylamine, flowing the solution through a column containing the phenol-formaldehyde type cation exchange resin to selectively adsorb substantially all the thorium values and a portion of the uranium values, flowing a dilute solution of hydrochloric acid through the column to desorb the uranium values, and then flowing a dilute aqueous acidic solution containing an ion, such as bisulfate, which has a complexing effect upon thortum through the column to desorb substantially all of the thorium.

  19. The Effect of Fluoride in Osteoporosis.

    ERIC Educational Resources Information Center

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

    1987-01-01

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

  20. Anhydrous hydrogen fluoride electrolyte battery. [Patent application

    DOEpatents

    Not Available

    1972-06-26

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